CN116057075A

CN116057075A - Acrylic rubber sheet excellent in roll processability and banbury processability

Info

Publication number: CN116057075A
Application number: CN202180057041.2A
Authority: CN
Inventors: 增田浩文; 川中孝文
Original assignee: Zeon Corp
Current assignee: Zeon Corp
Priority date: 2020-06-05
Filing date: 2021-06-04
Publication date: 2023-05-02
Also published as: JPWO2021246513A1; KR20230019826A; WO2021246513A1

Abstract

The invention provides an acrylic rubber sheet with excellent roller processability and Banbury processability. The acrylic rubber sheet of the present invention has an ion-reactive group, and has a ratio (Mz/Mw) of a z-average molecular weight (Mz) to a weight-average molecular weight (Mw) of an absolute molecular weight distribution measured by GPC-MALS method of 1.8 or more and a gel content of 30 wt% or less.

Description

Acrylic rubber sheet excellent in roll processability and banbury processability

Technical Field

The present invention relates to an acrylic rubber sheet, a method for producing the same, an acrylic rubber bag, a rubber mixture, and a rubber crosslinked product, and more particularly to an acrylic rubber sheet excellent in roll processability and banbury processability, and excellent in crosslinking property, strength characteristic characteristics, and compression set resistance characteristics, a method for producing the same, an acrylic rubber bag obtained by laminating the acrylic rubber sheet, a rubber mixture containing the acrylic rubber sheet or the acrylic rubber bag, and a rubber crosslinked product obtained by crosslinking the same.

Background

Acrylic rubber is a polymer containing an acrylic ester as a main component, and is generally considered to be a rubber excellent in heat resistance, oil resistance, and ozone resistance, and is widely used in fields related to automobiles, and the like.

For example, patent document 1 (pamphlet of international publication No. 2019/188709) discloses the following method: after repeating deaeration under reduced pressure and nitrogen substitution by adding a monomer component composed of ethyl acrylate, butyl acrylate, methoxyethyl acrylate and monobutyl fumarate, water and sodium lauryl sulfate, emulsion polymerization was initiated at normal pressure and normal temperature by adding sodium aldehyde sulfoxylate and cumene hydroperoxide as an organic radical generator, and the resulting mixture was subjected to emulsion polymerization until the polymerization conversion became 95% by weight, and then coagulated with a calcium chloride aqueous solution, filtered through a wire gauze, and dehydrated and dried by using an extrusion dryer having a screw, to thereby produce an acrylic rubber. However, the acrylic rubber obtained by this method has problems of extremely poor roll processability and banbury processability, and also poor storage stability and water resistance. Patent document 1 does not describe sheeting the obtained acrylic rubber.

Patent document 2 (japanese patent application laid-open No. 1-135811) discloses the following method: a monomer component comprising ethyl acrylate, caprolactone-added acrylate, cyanoethyl acrylate and vinyl chloride is prepared, 1/4 of the monomer mixture comprising the monomer component and n-dodecyl mercaptan as a chain transfer agent is emulsified with sodium lauryl sulfate, polyethylene glycol nonylphenyl ether and distilled water, sodium sulfite and ammonium persulfate as an inorganic radical generator are added to initiate polymerization, the remaining part of the monomer mixture and a 2% ammonium persulfate aqueous solution are dropwise added while maintaining the temperature at 60 ℃ for 2 hours, polymerization is continued for 2 hours after the dropwise addition, and latex having a polymerization conversion of 96 to 99% is put into a sodium chloride aqueous solution at 80 ℃ to be coagulated, and then dried after sufficient water washing, whereby an acrylic rubber is produced and crosslinked with sulfur. However, the acrylic rubber obtained by this method has problems of insufficient roll processability and banbury processability, and poor storage stability, strength characteristics of crosslinked products, and water resistance.

Patent document 3 (japanese patent application laid-open No. 2018-168343) discloses the following method: a monomer emulsion comprising ethyl acrylate, butyl acrylate and monobutyl fumarate, pure water, sodium lauryl sulfate, polyethylene glycol monostearate and n-dodecyl mercaptan as a chain transfer agent was prepared, then 1 part of the monomer emulsion and pure water were charged into a polymerization tank, cooled to 12℃and then the remaining part of the monomer emulsion, ferrous sulfate, sodium ascorbate and potassium persulfate as an inorganic radical generator were continuously added dropwise over 2.5 hours, then kept at 23℃for 1 hour, after continuing the reaction, industrial water was added, after heating to 85℃and then sodium sulfate was continuously added at 85℃to thereby solidify to obtain pellets, and after washing with pure water 3 times, it was dried with a hot air dryer to produce an acrylic rubber, and crosslinked with 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane. However, the acrylic rubber obtained by this method is excellent in stress relaxation property and extrusion processability, but has problems of insufficient roll processability, banbury processability and storage stability, and poor strength properties and water resistance of the crosslinked product.

Patent document 4 (japanese patent application laid-open No. 9-143229) discloses the following method: a monomer mixture of ethyl acrylate, a special acrylic ester and vinyl monochloride is added with sodium lauryl sulfate as an emulsifier, n-octyl mercaptan as a chain transfer agent and water into a reaction vessel, nitrogen substitution is carried out, then ammonium bisulfide and sodium persulfate as an inorganic free radical generator are added to initiate polymerization reaction, copolymerization is carried out for 3 hours at 55 ℃ at a reaction conversion rate of 93-96%, acrylic rubber is produced, and crosslinking is carried out with sulfur. However, the acrylic rubber obtained by this method has problems of insufficient banbury processability, and poor strength characteristics and water resistance of the crosslinked product.

Patent document 5 (japanese patent application laid-open No. 62-64809) discloses an acrylic rubber which is excellent in processability, compression set and tensile strength and which can be vulcanized with sulfur, and is characterized in that the acrylic rubber is a copolymer composed of 50 to 99.9% by weight of at least one compound of an alkyl acrylate and an alkoxyalkyl acrylate, 0.1 to 20% by weight of a dihydrodicyclopentenyl group-containing ester of an unsaturated carboxylic acid having a radical reactive group, 0 to 20% by weight of another monomer composed of at least one of a mono-1, 1-vinylidene (vinyl) and a mono-1, 2-vinylidene (vinyl) unsaturated compound, and the polystyrene-converted number average molecular weight (Mn) of tetrahydrofuran as an eluent is 20 to 120 ten thousand, and the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 10 or less. It is also described that the number average molecular weight (Mn) is 20 to 100 ten thousand, preferably 20 to 100 ten thousand, and if Mn is less than 20 ten thousand, the physical properties and processability of the sulfide are poor, if it is more than 120 ten thousand, and the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is not preferable, and if it is more than 10, the compression set is large. As specific examples thereof, the following manufacturing methods are disclosed: the acrylic rubber containing ethyl acrylate, a monomer component such as radical crosslinkable dicyclopentenyl acrylate, sodium lauryl sulfate as an emulsifier, potassium persulfate as an inorganic radical generator, octyl mercaptoglycolate as a molecular weight regulator, and tert-dodecyl mercaptan is added in varying amounts, and polymerized to obtain an acrylic rubber having a number average molecular weight (Mn) of 53 to 115 ten thousand, a weight average molecular weight (Mw) of 354 to 626 ten thousand, and a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 4.7 to 8, and after solidification in a calcium chloride aqueous solution, it is sufficiently washed with water and directly dried. Further, the following are shown in examples and comparative examples The content is as follows: if the amount of the chain transfer agent is small, the number average molecular weight (Mn) of the obtained acrylic rubber is as high as 500 ten thousand, the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) becomes smaller than 1.4, and if the amount of the chain transfer agent is large, the number average molecular weight (Mn) is as small as 20 ten thousand, and the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) becomes extremely large as 17. However, the acrylic rubber obtained by this method has poor compression set resistance and storage stability, and therefore has problems of insufficient banbury processability and roll processability because it contains a radical-reactive group, even if a suitable molecular weight distribution (Mw/Mn) is obtained in a polymerization reaction using a radical generator, the molecular weights (Mw, mn) are too large and too complex. In addition, for the acrylic rubber obtained by this method, sulfur as a crosslinking agent and a vulcanization accelerator were added in the crosslinking reaction, and after kneading with a roll, 100kg/cm was carried out at 170℃for 15 minutes ² Further, crosslinking at 175℃for 4 hours in a Gill oven (binder over) has a problem that the resulting crosslinked product is required to be crosslinked for a long period of time, and the resulting crosslinked product is poor in compression set characteristics, water resistance and strength characteristics, and also poor in physical property change after thermal deterioration.

On the other hand, regarding the acrylic rubber formed into a sheet, for example, patent document 6 (japanese patent application laid-open No. 2019-119772) discloses the following method: after a monomer component formed of ethyl acrylate, butyl acrylate, methoxyethyl acrylate and monobutyl maleate was made into a monomer emulsion by pure water and sodium lauryl sulfate and polyoxyethylene lauryl ether as emulsifiers, a part of the monomer emulsion was put into a polymerization reaction tank, cooled down to 12 ℃ under a nitrogen stream, then the remaining part of the monomer emulsion, ferrous sulfate, sodium ascorbate and an aqueous potassium persulfate solution as an inorganic radical generator were continuously added dropwise over 3 hours, then, the mixture was kept at 23 ℃ for further emulsion polymerization for 1 hour, after the polymerization conversion rate reached 97 wt%, the mixture was heated to 85 ℃, then, sodium sulfate was continuously added, thereby solidification was performed, filtration was performed to obtain aqueous pellets, and after 4 times of washing with water, 1 time of washing with acid, and 1 time of washing with pure water, acrylic rubber was continuously produced into a sheet shape by an extrusion dryer with a screw, and crosslinked with aliphatic polyamine compounds such as hexamethylenediamine carbamate. However, the sheet-like acrylic rubber obtained by this method has problems of poor roll processability, storage stability, and poor water resistance of crosslinked products.

Further, regarding the gel amount of the acrylic rubber, for example, patent document 7 (japanese patent No. 3599962) discloses an acrylic resin composition excellent in extrusion processability such as extrusion speed, die swell (die swell), surface texture, and the like, which comprises the acrylic rubber obtained by copolymerizing 95 to 99.9% by weight of an alkyl acrylate or an alkoxyalkyl acrylate with 0.1 to 5% by weight of a polymerizable monomer having 2 or more radically reactive unsaturated groups different in reactivity in the presence of a radical polymerization initiator, and a reinforcing filler and an organic peroxide-based vulcanizing agent, and the gel percentage as an acetone-insoluble component is 5% by weight or less. The acrylic rubber used herein having a very small gel fraction is obtained by: the polymerization solution is adjusted to pH6 to 8 with sodium bicarbonate or the like under the condition that the polymerization solution is in a normal acidic region (pH 4 before polymerization, pH3.4 after polymerization) to obtain an acrylic rubber having a high gel fraction (60%). Specifically, water, sodium lauryl sulfate and polyoxyethylene nonylphenyl ether as emulsifiers, sodium carbonate, and boric acid were added, and after adjusting to 75 ℃, tert-butyl hydroperoxide, sodium formaldehyde sulfoxylate, disodium ethylenediamine tetraacetate, and ferrous sulfate (pH at this time was 7.1) as organic radical generators were added, and then, monomer components of ethyl acrylate and allyl methacrylate were added dropwise to conduct emulsion polymerization, and the resulting emulsion (pH 7) was salted out using a sodium sulfate aqueous solution, and washed with water, and dried to obtain an acrylic rubber. However, the acrylic rubber containing (meth) acrylic acid ester as a main component is decomposed in the neutral to alkaline region, and there are problems of poor storage stability and strength characteristics even if processability is improved, and also problems of poor roll processability, banbury processability, crosslinkability and compression set resistance.

Further, patent document 8 (pamphlet of international publication No. 2018/143101) discloses the following technique: the extrusion moldability, particularly extrusion amount, extrusion length and surface texture of a rubber composition containing a reinforcing agent and a crosslinking agent are improved by emulsion polymerizing a (meth) acrylate and an ion-crosslinkable monomer, and using an acrylic rubber having a complex viscosity at 100 ℃ ([ eta ]100 ℃) of 3500 Pa.s or less and a ratio of complex viscosity at 100 ℃ ([ eta ]100 ℃) to complex viscosity at 60 ℃ ([ eta ]60 ℃) ([ eta ]100 ℃/[ eta ]60 ℃). The same technique also describes that the gel content of the acrylic rubber used as a THF (tetrahydrofuran) insoluble component is 80% by weight or less, preferably 5 to 80% by weight, and preferably as much as possible in the range of 70% or less, and if the gel content is less than 5%, the extrudability is deteriorated. It is also described that the weight average molecular weight (Mw) of the acrylic rubber used is 200000 ～ 1000000, and if the weight average molecular weight (Mw) is more than 1000000, the viscoelasticity of the acrylic rubber is too high, which is not preferable. However, no method for improving the workability of rolls, banbury and the like has been described.

Prior art literature

Patent literature

Patent document 1: international publication No. 2019/188709;

patent document 2: japanese patent laid-open No. 1-135811;

patent document 3: japanese patent application laid-open No. 2018-168343;

patent document 4: japanese patent laid-open No. 9-143229;

patent document 5: japanese patent laid-open No. 62-64809;

patent document 6: japanese patent application laid-open No. 2019-119772;

patent document 7: japanese patent No. 3599962;

patent document 8: international publication No. 2018/143101.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described circumstances of the prior art, and an object thereof is to provide an acrylic rubber sheet excellent in both roll processability and banbury processability and also excellent in crosslinking property, strength characteristics and compression set resistance in a short time, a method for producing the same, an acrylic rubber bag obtained by laminating the acrylic rubber sheet, a rubber mixture containing the acrylic rubber sheet or the acrylic rubber bag, and a crosslinked rubber product obtained by crosslinking the same.

Solution for solving the problem

The present inventors have made intensive studies in view of the above problems, and as a result, have found that an acrylic rubber sheet containing an ion-reactive group and having a high ratio (Mz/Mw) of z-average molecular weight (Mz) to weight-average molecular weight (Mw) which is a high molecular weight component in an absolute molecular weight and absolute molecular weight distribution measured by GPC-MALS method, and having a gel content in a specific range, is excellent in roll processability and banbury processability, and is excellent in short-time crosslinkability, strength characteristics and compression set resistance.

The present inventors have found that an acrylic rubber sheet formed from an acrylic rubber having an ion-reactive group capable of reacting with a crosslinking agent such as a carboxyl group, an epoxy group, or a chlorine atom and having a ratio (Mz/Mw) of z-average molecular weight (Mz) to weight-average molecular weight (Mw) of an absolute molecular weight distribution in a high molecular weight region measured by a GPC-MALS method is excellent in short-time crosslinkability, strength characteristics, and compression set resistance.

The present inventors have also found that, in the GPC measurement of the above-mentioned acrylic rubber having an ion-reactive group and having a large absolute molecular weight distribution in a high molecular weight region, the radical-reactive acrylic rubber obtained by copolymerizing ethyl acrylate and dicyclopentenyl acrylate and the like in the above-mentioned conventional art is not sufficiently dissolved in tetrahydrofuran to be used in the GPC measurement, and the molecular weight and analytical weight distribution cannot be clearly and reproducibly measured, but the specific solvent having an SP value higher than that of tetrahydrofuran is used as an eluent, and the solvent can be thoroughly dissolved and reproducibly measured well, and the roll processability, the bery processability, the crosslinkability, the strength property and the compression set resistance property of the acrylic rubber sheet can be highly balanced by specifying the specific characteristic values.

The present inventors have found that, regarding the roll processability of an acrylic rubber sheet, the roll processability can be improved without impairing the strength characteristics by increasing the ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) which is the main high molecular weight component in the absolute molecular weight distribution measured by the GPC-MALS method. The inventors have found that the above-mentioned ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) can be increased by adding the reducing agent in portions during the polymerization without adding the chain transfer agent at the initial stage, and preferably by adding the reducing agent after the addition. The present inventors have also found that the larger the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the absolute molecular weight distribution measured by the GPC-MALS method is, the more improved the roll processability is possible, and that it is possible to achieve this by adding the chain transfer agent in batches during the polymerization, more preferably by kneading and drying the aqueous pellets with high shear in a screw type biaxial extrusion dryer.

The present inventors have also found that, regarding the banbury processability of the acrylic rubber sheet, the smaller the gel amount of the acrylic rubber sheet, the more excellent. The gel amount of the methyl ethyl ketone-insoluble component of the acrylic rubber sheet is preferably generated during the polymerization reaction of the acrylic rubber, and particularly if the polymerization conversion is improved in order to improve the strength characteristics, the gel amount is rapidly increased and difficult to control, but by performing emulsion polymerization in the presence of a chain transfer agent in the latter half of the polymerization reaction, the inhibition can be made to a certain extent, and the gel amount of the rapidly increased methyl ethyl ketone-insoluble component can be remarkably improved in the banbury processability by melt kneading and extrusion drying the acrylic rubber in a state substantially free of moisture (water content less than 1 wt%) in the screw type biaxial extrusion dryer, without impairing the strength characteristics of the acrylic rubber sheet.

The present inventors have also found that by specifying the ash content in the acrylic rubber sheet and the component content in the ash, it is possible to further improve roll processability, banbury processability, short-time crosslinkability, strength characteristics and compression set resistance, and also to improve water resistance. It has been found that although it is difficult to reduce the ash content of an acrylic rubber emulsion-polymerized using a large amount of an emulsifier or a coagulant, the aqueous pellet produced by a specific coagulation method is particularly excellent in cleaning efficiency with hot water and ash removal efficiency in dehydration, and the ash content in the produced acrylic rubber sheet can be greatly reduced, thereby significantly improving water resistance. In addition, it has been found that the water resistance and handleability can be greatly improved by specifying the ash component in ash. The present inventors have also found that when a specific emulsifier is used in emulsion polymerization of an acrylic rubber or a specific coagulant is used in coagulation of an emulsion polymerization liquid, the acrylic rubber sheet can be made excellent in water resistance and release properties to a metal mold or the like can be significantly improved.

The present inventors have also found that by making the specific gravity of the acrylic rubber sheet large or making the pH in a specific range, it is possible to make excellent roll processability, banbury processability, crosslinkability, strength characteristics and compression set resistance characteristics, and also to make excellent storage stability. In particular, it has been found that the acrylic rubber sheet having a high specific gravity means that air is not contained, and thus the storage stability of the acrylic rubber sheet can be greatly improved. In the conventional acrylic rubber sheet, a large amount of air is contained when the aqueous pellet produced in the coagulation step is dried, and the storage stability is deteriorated, but it has been found that the specific gravity of the molded article can be increased and the storage stability can be improved by slightly compacting the dried rubber obtained by directly drying the aqueous pellet with a high-pressure packing machine or the like, and it is preferable to extrude the dried rubber obtained by drying the aqueous pellet produced in the coagulation step in a specific extrusion dryer in an air-free state into a sheet form, to produce an acrylic rubber sheet having particularly excellent storage stability.

The present inventors have also found that by increasing the cooling rate after drying, the mooney scorch stability can be significantly improved without impairing the roll processability, banbury processability, water resistance, strength characteristics and compression set resistance characteristics of the acrylic rubber sheet.

The present inventors have also found that by setting the monomer composition, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw/Mn), the number average molecular weight (Mn), the complex viscosity at 60 ℃ ([ eta ]60 ℃), the complex viscosity at 100 ℃ ([ eta ]100 ℃) and the complex viscosity at 60 ℃ ([ eta ]60 ℃) of the acrylic rubber within specific ranges ([ eta ]100 ℃/[ eta ]60 ℃), the roll processability, the Banbury processability, the crosslinkability, the strength properties and the compression set resistance properties can be further improved significantly, and by using a multi-component organic compound as a crosslinking agent, the crosslinkability in a short period of time and the respective properties of the resulting rubber crosslinked product can be further improved significantly.

The present inventors have also found that an acrylic rubber sheet having a high molecular weight distribution and a small gel amount and excellent roll processability, banbury processability, crosslinkability, strength characteristics and compression set resistance characteristics, which is obtained by emulsifying a specific monomer component in water and an emulsifier, then initiating emulsion polymerization in the presence of a redox catalyst containing an inorganic radical generator such as potassium persulfate and a reducing agent, and then adding the emulsion polymerization in batches during polymerization without adding a chain transfer agent in the initial stage, and dehydrating, drying and molding an aqueous pellet produced during solidification by using a specific screw type extrusion dryer.

The present inventors have further found that an acrylic rubber sheet having further improved roll processability, banbury processability, short-time crosslinkability, strength characteristics and compression set resistance characteristics can be produced by melt-kneading and drying an acrylic rubber under high shear conditions using a specific extrusion dryer.

The present inventors have also found that an acrylic rubber bag excellent in handling properties and storage stability, roll processability, banbury processability, short-time crosslinkability, water resistance, strength properties and compression set resistance can be easily produced by laminating acrylic rubber sheets excellent in roll processability, banbury processability, short-time crosslinkability, strength properties and compression set resistance and also excellent in storage stability and water resistance.

The present inventors have further found that blending carbon black and silica as fillers in a rubber mixture comprising the acrylic rubber sheet or the acrylic rubber bag of the present invention, a filler and a crosslinking agent makes the crosslinked product excellent in roll processability, banbury processability and short-time crosslinkability and also excellent in water resistance, strength characteristics and compression set resistance. The present inventors have also found that, as the crosslinking agent, an organic compound, a polyvalent compound or an ionic crosslinking compound is preferable, for example, a polyvalent ionic organic compound having a plurality of ion-reactive groups reactive with ion-reactive groups of an acrylic rubber bag such as an amine group, an epoxy group, a carboxyl group or a thiol group, is excellent in roll processability, banbury processability and crosslinking property in a short period of time, and the crosslinked product is extremely excellent in water resistance, strength characteristics and compression set resistance.

The present inventors have completed the present invention based on these findings.

Thus, according to the present invention, there can be provided an acrylic rubber sheet having an ion-reactive group, wherein the ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) of the absolute molecular weight distribution measured by GPC-MALS method is 1.8 or more, and the gel amount is 30 wt% or less.

In the acrylic rubber sheet of the present invention, the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the absolute molecular weight distribution measured by GPC-MALS method is preferably 3.5 or more.

In the acrylic rubber sheet of the present invention, the number average molecular weight (Mn) of the absolute molecular weight measured by GPC-MALS method is preferably in the range of 10 to 50 tens of thousands.

In the acrylic rubber sheet of the present invention, the weight average molecular weight (Mw) of the absolute molecular weight measured by GPC-MALS method is preferably in the range of 100 to 350 ten thousand.

In the acrylic rubber sheet of the present invention, the measurement solvent by GPC-MALS method is preferably dimethylformamide-based solvent.

In the acrylic rubber sheet of the present invention, the gel amount is preferably 15% by weight or less.

In the acrylic rubber sheet of the present invention, the gel amount is preferably an amount of methyl ethyl ketone insoluble component.

In the acrylic rubber sheet of the present invention, it is preferable that the acrylic rubber is formed of a binding unit derived from at least one (meth) acrylate selected from the group consisting of an alkyl (meth) acrylate and an alkoxyalkyl (meth) acrylate, a binding unit derived from an ion-reactive group-containing monomer, and a binding unit derived from another monomer.

In the acrylic rubber sheet of the present invention, the ash content is preferably 1% by weight or less.

In the acrylic rubber sheet of the present invention, the total amount of sodium, magnesium, calcium, phosphorus and sulfur in ash is preferably 50% by weight or more.

In the acrylic rubber sheet of the present invention, the complex viscosity at 60 ℃ ([ eta ]60 ℃) is preferably 15000[ Pa.s ] or less.

In the acrylic rubber sheet of the present invention, the ratio of the complex viscosity at 100 ℃ ([ eta ]100 ℃) to the complex viscosity at 60 ℃ ([ eta ]60 ℃) ([ eta ]100 ℃/[ eta ]60 ℃)) is preferably 0.8 or more.

In the acrylic rubber sheet of the present invention, the pH is preferably in the range of 3 to 6.

The acrylic rubber sheet of the present invention is preferably a melt-kneaded sheet.

In the acrylic rubber sheet of the present invention, the content of the acrylic rubber in the acrylic rubber sheet is preferably 90% by weight or more.

The acrylic rubber sheet of the present invention is preferably emulsion polymerized using a phosphate salt or a sulfate salt as an emulsifier, and the polymerization solution after emulsion polymerization is coagulated, preferably by using an alkali metal salt or a group 2 metal salt of the periodic table as a coagulant, and dried.

The acrylic rubber sheet of the present invention is preferably subjected to melt kneading and drying after solidification, and the melt kneading and drying are preferably performed in a state substantially free of moisture, and the melt kneading and drying are preferably performed under reduced pressure. Further, the acrylic rubber sheet of the present invention is preferably cooled at a cooling rate of 40℃per hour or more after the above-mentioned melt kneading and drying.

According to the present invention, there is also provided a method for producing an acrylic rubber sheet, comprising the steps of: an emulsifying step of emulsifying an acrylic rubber monomer component containing an ion-reactive group-containing monomer with water and an emulsifier; an emulsion polymerization step of initiating a polymerization reaction in the presence of a redox catalyst comprising an inorganic radical generator and a reducing agent, adding a chain transfer agent after the batch during the polymerization, and continuing the polymerization to obtain an emulsion polymerization solution; a coagulation step of coagulating the emulsion polymerization liquid obtained with a coagulating liquid to produce an aqueous pellet; a cleaning step of cleaning the produced aqueous pellets; a dehydration step of dehydrating the washed aqueous pellets in a dehydration cylinder to a water content of 1 to 40 wt% using a dehydration cylinder having a dehydration slit, a dryer cylinder under reduced pressure, and a screw type biaxial extrusion dryer having a die at the tip; a drying step of drying in a dryer barrel to less than 1% by weight; and a molding step of extruding the sheet-like dry rubber from the die.

The method for producing an acrylic rubber sheet of the present invention is preferably a method for producing an acrylic rubber sheet as described above.

In the method for producing an acrylic rubber sheet of the present invention, the maximum torque of the screw type biaxial extrusion dryer is preferably 25n·m or more.

In the method for producing an acrylic rubber sheet of the present invention, the reducing agent is preferably added later.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable to perform emulsion polymerization using a phosphate salt or a sulfate salt as an emulsifier in the emulsion polymerization step.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable to coagulate the polymerization liquid produced in the emulsion polymerization step by using an alkali metal salt or a group 2 metal salt of the periodic table as a coagulant, and then dry the coagulated polymerization liquid.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable that the polymerization liquid produced in the emulsion polymerization step is added to an aqueous solution containing a coagulant containing an alkali metal salt or a group 2 metal salt of the periodic table and stirred to be coagulated.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable that the polymerization liquid produced in the emulsion polymerization step is brought into contact with a coagulant to solidify, and then melt kneaded and dried.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable that the melt kneading and drying are carried out in a state substantially free of moisture.

In the method for producing an acrylic rubber sheet of the present invention, the melt kneading and drying are preferably performed under reduced pressure.

In the method for producing an acrylic rubber sheet of the present invention, the acrylic rubber after melt-kneading and drying is preferably cooled at a cooling rate of 40 ℃/hr or more.

According to the present invention, there is also provided an acrylic rubber bag formed by laminating the acrylic rubber sheets.

In the acrylic rubber bag of the present invention, it is preferable that the amount of gel in the acrylic rubber bag is sampled at any number of points to measure the value at the time of deviation, and the measured samples are all within the range of (average value.+ -. 5% by weight).

In the acrylic rubber bag of the present invention, it is preferable that the plural samples are 20 samples.

In the acrylic rubber bag of the present invention, the specific gravity is preferably 0.8 or more.

According to the present invention, there is also provided a rubber mixture comprising the acrylic rubber sheet and/or the acrylic rubber bag, a filler, and a crosslinking agent.

In the rubber mixture of the present invention, the filler is preferably a reinforcing filler. In the rubber mixture of the present invention, the filler is preferably carbon black. In the rubber mixture of the present invention, the filler is preferably silica.

In the rubber mixture of the present invention, the crosslinking agent is preferably an organic crosslinking agent. In the rubber mixture of the present invention, the crosslinking agent is preferably a polyvalent compound. In the rubber mixture of the present invention, the crosslinking agent is preferably an ion-crosslinkable compound. In the rubber mixture of the present invention, the crosslinking agent is preferably an ion-crosslinkable organic compound. In the rubber mixture of the present invention, the crosslinking agent is preferably a polyionic organic compound.

In the rubber mixture of the present invention, it is preferable that the ion of the ion-crosslinkable compound, ion-crosslinkable organic compound or polyion-crosslinkable organic compound as the crosslinking agent is at least one ion-reactive group selected from the group consisting of an amino group, an epoxy group, a carboxyl group and a thiol group.

In the rubber mixture of the present invention, the crosslinking agent is preferably at least one polyionic compound selected from the group consisting of a polyamine compound, a polyepoxide compound, a polycarboxylic acid compound and a polythiol compound.

In the rubber mixture of the present invention, the content of the crosslinking agent is preferably in the range of 0.001 to 20 parts by weight per 100 parts by weight of the rubber component.

The rubber mixture of the present invention preferably further contains an antioxidant. In the rubber mixture of the present invention, the antioxidant is preferably an amine-based antioxidant.

According to the present invention, there is also provided a method for producing a rubber mixture, comprising mixing a rubber component comprising the acrylic rubber sheet or the acrylic rubber bag, a filler, and an antioxidant, if necessary, and then mixing a crosslinking agent.

According to the present invention, there is further provided a crosslinked rubber product obtained by crosslinking the rubber mixture. In the rubber crosslinked product of the present invention, the crosslinking of the rubber mixture is preferably performed after molding. In the rubber crosslinked product of the present invention, it is preferable that the crosslinking of the rubber mixture is a crosslinking in which primary crosslinking and secondary crosslinking are performed.

Effects of the invention

According to the present invention, it is possible to provide an acrylic rubber sheet excellent in roll processability, banbury processability, short-time crosslinkability, strength characteristics and compression set characteristics, an efficient production method thereof, an acrylic rubber bag obtained by laminating the acrylic rubber sheet, a high-quality rubber mixture obtained by mixing the acrylic rubber sheet or the acrylic rubber bag, and a crosslinked rubber product obtained by crosslinking the same.

Drawings

Fig. 1 is a diagram schematically showing an example of an acrylic rubber manufacturing system for manufacturing an acrylic rubber sheet and an acrylic rubber bag according to an embodiment of the present invention.

Fig. 2 is a diagram showing the structure of a screw extruder.

Fig. 3 is a diagram showing a configuration of a conveyor type cooling device used as the cooling device of fig. 1.

Detailed Description

The acrylic rubber sheet of the present invention is characterized by comprising an acrylic rubber having an ion-reactive group and having a ratio (MZ/Mw) of a z-average molecular weight (Mz) to a weight-average molecular weight (Mw) of an absolute molecular weight distribution measured by GPC-MALS method of 1.8 or more, and by having a gel content of 30 wt% or less. The term "GPC-MALS method" as used herein refers to the following. GPC (gel permeation chromatography ) is a liquid chromatography method that separates based on differences in molecular size. A multi-angle laser light scattering detector (MALS) and a differential refractive index detector (RI) are assembled in the device, the light scattering intensity and refractive index difference of a molecular chain solution classified by size are measured according to dissolution time by a GPC device, the molecular weight of a solute and the content thereof are sequentially calculated, and finally the absolute molecular weight distribution and absolute average molecular weight value of a polymer substance are obtained.

< ion-reactive group >

The acrylic rubber sheet of the present invention is characterized by having an ion-reactive group.

The ion-reactive group is not particularly limited as long as it is a functional group capable of undergoing an ion reaction, and is preferably at least one functional group selected from the group consisting of a carboxyl group, an epoxy group and a chlorine atom, more preferably an epoxy group and a carboxyl group, and particularly preferably a carboxyl group.

The content of the ion-reactive group in the acrylic rubber sheet of the present invention is not particularly limited and may be appropriately selected depending on the purpose of use, but is usually in the range of 0.001 to 5% by weight, preferably 0.01 to 3% by weight, more preferably 0.05 to 1% by weight, and particularly preferably 0.1 to 0.5% by weight, based on the weight of the ion-reactive group itself, and in this case, the processability, crosslinkability, and the properties such as the strength property when used as a crosslinked product, compression set resistance, oil resistance, cold resistance, water resistance and the like are highly balanced, and thus are preferable.

The acrylic rubber sheet having the ion-reactive group of the present invention may be formed by introducing the ion-reactive group into an acrylic rubber in a post-reaction, and is preferably formed by copolymerizing an ion-reactive group-containing monomer.

< monomer component >

The monomer component of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited as long as it can constitute a usual acrylic rubber, and is preferably an acrylic rubber monomer component containing an ion-reactive group-containing monomer, more preferably a monomer component formed of at least one (meth) acrylate selected from the group consisting of an alkyl (meth) acrylate and an alkoxyalkyl (meth) acrylate, an ion-reactive group-containing monomer, and other monomers copolymerizable as needed. In the present invention, "(meth) acrylate" is used as a term for esters of acrylic acid and/or methacrylic acid.

The alkyl (meth) acrylate is not particularly limited, and an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms may be generally used, and an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms is preferably used, and an alkyl (meth) acrylate having an alkyl group having 2 to 6 carbon atoms is more preferably used.

Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like, and among these, ethyl (meth) acrylate, n-butyl (meth) acrylate, and more preferably ethyl acrylate and n-butyl acrylate.

The alkoxyalkyl (meth) acrylate is not particularly limited, and an alkoxyalkyl (meth) acrylate having an alkoxyalkyl group having 2 to 12 carbon atoms may be generally used, and an alkoxyalkyl (meth) acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms is preferably used, and an alkoxyalkyl (meth) acrylate having an alkoxyalkyl group having 2 to 6 carbon atoms is more preferably used.

Specific examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and the like. Among them, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and the like are preferable, and methoxyethyl acrylate and ethoxyethyl acrylate are more preferable.

These at least one (meth) acrylic acid ester selected from these alkyl (meth) acrylates and alkoxyalkyl (meth) acrylates may be used alone or in combination of 2 or more, and the proportion thereof in the total component of the monomer is usually in the range of 50 to 99.99% by weight, preferably 62 to 99.95% by weight, more preferably 74 to 99.9% by weight, particularly preferably 80 to 99.5% by weight, most preferably 87 to 99% by weight, and in this case, the acrylic rubber sheet is excellent in weather resistance, heat resistance and oil resistance, and is therefore preferred.

The ion-reactive group-containing monomer is not particularly limited as long as it has a functional group that participates in an ion reaction, and may be appropriately selected depending on the purpose of use, and generally, a monomer having at least one functional group selected from a carboxyl group, an epoxy group and a chlorine atom is preferable, and a monomer having a carboxyl group is more preferable, and in this case, the crosslinkability in a short period of time and compression set resistance and water resistance of a crosslinked product can be significantly improved.

The monomer having a carboxyl group is not particularly limited, and an ethylenically unsaturated carboxylic acid can be preferably used. Examples of the ethylenically unsaturated carboxylic acid include ethylenically unsaturated monocarboxylic acid, ethylenically unsaturated dicarboxylic acid, and ethylenically unsaturated dicarboxylic acid monoester, and among them, particularly, ethylenically unsaturated dicarboxylic acid monoester is preferable because it can further improve compression set resistance in the case of producing a rubber crosslinked product from an acrylic rubber sheet.

The ethylenically unsaturated monocarboxylic acid is not particularly limited, but preferably has 3 to 12 carbon atoms, and examples thereof include acrylic acid, methacrylic acid, α -ethacrylic acid, crotonic acid, cinnamic acid, and the like.

The ethylenically unsaturated dicarboxylic acid is not particularly limited, but an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms is preferable, and examples thereof include butenedioic acid such as fumaric acid and maleic acid, itaconic acid and citraconic acid. In addition, the ethylenically unsaturated dicarboxylic acid comprises a dicarboxylic acid in the form of an anhydride.

The ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, and examples thereof include alkyl monoesters having 1 to 12 carbon atoms of an ethylenically unsaturated dicarboxylic acid, preferably alkyl monoesters having 2 to 8 carbon atoms of an ethylenically unsaturated dicarboxylic acid having 4 to 6 carbon atoms, and more preferably alkyl monoesters having 2 to 6 carbon atoms of an ethylenically unsaturated dicarboxylic acid having 4 carbon atoms.

Specific examples of the ethylenically unsaturated dicarboxylic acid monoester include: mono-alkyl butenedioates such as monomethyl fumarate, monoethyl fumarate, mono-n-butyl fumarate, monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, and the like; mono-alkyl itaconates such as monomethyl itaconate, monoethyl itaconate, mono-n-butyl itaconate and monocyclohexyl itaconate, and among them, mono-n-butyl fumarate and mono-n-butyl maleate are preferable, and mono-n-butyl fumarate is particularly preferable.

Examples of the monomer having an epoxy group include: epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate; vinyl ethers containing an epoxy group such as allyl glycidyl ether and vinyl glycidyl ether.

Examples of the monomer having a chlorine atom include, but are not particularly limited to, unsaturated alcohol esters of saturated carboxylic acids having a chlorine atom, chloroalkyl (meth) acrylates, chloroacyloxy alkyl (meth) acrylates, (chloroacetylcarbamoyloxy) alkyl (meth) acrylates, unsaturated ethers having a chlorine atom, unsaturated ketones having a chlorine atom, aromatic vinyl compounds having a chlorine methyl group, unsaturated amides having a chlorine atom, and unsaturated monomers having a chlorine acetyl group.

Specific examples of the unsaturated alcohol ester of a chlorine-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, allyl chloroacetate, and the like. Specific examples of the chloroalkyl (meth) acrylate include chloromethyl (meth) acrylate, 1-chloroethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 1, 2-dichloroethyl (meth) acrylate, 2-chloropropyl (meth) acrylate, 3-chloropropyl (meth) acrylate, and 2, 3-dichloropropyl (meth) acrylate. Specific examples of the chloroacetoxy alkyl (meth) acrylate include 2- (chloroacetoxy) ethyl (meth) acrylate, 2- (chloroacetoxy) propyl (meth) acrylate, 3- (chloroacetoxy) propyl (meth) acrylate, and 3- (hydroxychloroacetoxy) propyl (meth) acrylate. Examples of the (chloroacetylcarbamoyloxy) alkyl (meth) acrylate include: 2- (chloroacetylcarbamoyloxy) ethyl (meth) acrylate, 3- (chloroacetylcarbamoyloxy) propyl (meth) acrylate, and the like. Specific examples of the unsaturated ether containing chlorine atoms include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, and 3-chloropropyl allyl ether. Specific examples of the unsaturated ketone containing chlorine atoms include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, and 2-chloroethyl allyl ketone. Specific examples of the chloromethyl-containing aromatic vinyl compound include p-chloromethyl styrene, m-chloromethyl styrene, o-chloromethyl styrene, and p-chloromethyl- α -methylstyrene. Specific examples of the unsaturated amide containing chlorine atoms include N-chloromethyl (meth) acrylamide and the like. Specific examples of the chloracetyl-containing unsaturated monomer include 3- (hydroxychloroacetoxy) propyl allyl ether, p-vinylbenzyl chloroacetate, and the like.

These ion-reactive group-containing monomers may be used singly or in combination of 2 or more, and the proportion thereof in the total monomer components is usually in the range of 0.01 to 10% by weight, preferably 0.05 to 8% by weight, more preferably 0.1 to 6% by weight, particularly preferably 0.5 to 5% by weight, and most preferably 1 to 3% by weight.

The monomer other than the above (simply referred to as "other monomer" in the present invention) that can be used together with the above-mentioned monomers as needed is not particularly limited as long as it can be copolymerized with the above-mentioned monomer, and examples thereof include: aromatic vinyl monomers such as styrene, α -methylstyrene, divinylbenzene, and the like; ethylenically unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; acrylamide monomers such as acrylamide and methacrylamide; olefin monomers such as ethylene, propylene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, and the like.

These other monomers may be used alone or in combination of 2 or more, and the proportion thereof in the whole monomer component is usually controlled to be in the range of 0 to 40% by weight, preferably 0 to 30% by weight, more preferably 0 to 20% by weight, particularly preferably 0 to 15% by weight, most preferably 0 to 10% by weight.

< acrylic rubber >

The acrylic rubber constituting the acrylic rubber sheet of the present invention has the above-mentioned ion-reactive group, and is preferably formed of the above-mentioned at least one (meth) acrylic acid ester selected from the group consisting of the (meth) acrylic acid alkyl ester and the (meth) alkoxyalkyl ester, the ion-reactive group-containing monomer, and, if necessary, the binding unit derived from the other monomer, and regarding the respective proportions in the acrylic rubber, the binding unit derived from the at least one (meth) acrylic acid ester selected from the group consisting of the (meth) acrylic acid alkyl ester and the (meth) alkoxyalkyl ester is usually 50 to 99.99% by weight, preferably 62 to 99.95% by weight, more preferably 74 to 99.9% by weight, particularly preferably 80 to 99.5% by weight, most preferably 87 to 99% by weight, the binding unit derived from the ion-reactive group-containing monomer is usually 0.01 to 10% by weight, preferably 0.05 to 8% by weight, more preferably 0.1 to 6% by weight, particularly preferably 0.5 to 5% by weight, most preferably 1 to 3% by weight, and the binding unit derived from the other monomer is usually 0 to 20% by weight to 30% by weight, most preferably 0 to 30% by weight. When the monomer composition of the acrylic rubber is within this range, the properties such as short-time crosslinkability, compression set resistance, weather resistance, heat resistance and oil resistance of the acrylic rubber sheet are highly balanced, and thus are preferable.

The solvent for measuring the GPC-MALS method for measuring the absolute molecular weight and the absolute molecular weight distribution of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited as long as the solvent can dissolve the acrylic rubber sheet of the present invention for measurement, and dimethylformamide-based solvents are preferable. The dimethylformamide-based solvent to be used is not particularly limited as long as it contains dimethylformamide as a main component, and the ratio of dimethylformamide to dimethylformamide in the dimethylformamide-based solvent is 100% by weight, preferably 95% by weight, and more preferably 97% by weight or more. In the present invention, lithium chloride and 37% concentrated hydrochloric acid are preferably added to dimethylformamide, respectively, so that the concentration of lithium chloride is 0.05mol/L and the concentration of hydrochloric acid is 0.01%.

The number average molecular weight (Mn) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, but is usually 100000 ～ 500000 (10 to 50 tens of thousands), preferably 200000 ～ 480000, more preferably 250000 ～ 450000, particularly preferably 300000 ～ 400000, and most preferably 350000 ～ 400000, in terms of absolute molecular weight measured by GPC-MALS method, and in this case, the roll processability, strength characteristics and compression set resistance of the acrylic rubber sheet are highly balanced and therefore preferable.

The weight average molecular weight (Mw) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, and is preferably in the range of 1200000 ～ 3000000, more preferably 1300000 ～ 3000000, particularly preferably 1500000 ～ 2500000, and most preferably 1900000 ～ 2100000, in terms of absolute molecular weight measured by GPC-MALS method, generally 1000000 ～ 3500000 (100 to 350 ten thousand), and in this case, the roll processability, strength characteristics and compression set characteristics of the acrylic rubber sheet are highly balanced.

The z-average molecular weight (Mz) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, and is preferably in the range of usually 1500000 ～ 6000000 (150 to 600 tens of thousands), preferably 2000000 ～ 5000000, more preferably 2500000 ～ 4500000, and particularly preferably 3000000 ～ 4000000, in terms of the absolute molecular weight of the important polymer region measured by GPC-MALS method, and in this case, the roll processability, banbury processability, strength characteristics and compression set resistance of the acrylic rubber sheet are highly balanced.

The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, and is usually 3 or more, preferably 3.4 or more, more preferably 3.5 or more, particularly preferably 3.6 or more, and most preferably 3.7 or more, in terms of absolute molecular weight measured by GPC-MALS method. If the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic rubber is too small, the roll processability of the acrylic rubber sheet is deteriorated, which is not preferable. The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is usually 3.7 to 6.5, preferably 3.8 to 6.2, more preferably 4 to 6, particularly preferably 4.5 to 5.7, and most preferably 4.7 to 5.5, and in this case, the roll processability, the strength characteristics in the case of being crosslinked, and the compression set resistance characteristics of the acrylic rubber sheet are highly balanced, and therefore, are preferable.

The ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is preferably in the range of 1.8 or more, preferably 1.8 to 2.4, more preferably 1.8 to 2, in terms of the absolute molecular weight distribution of the important polymer region measured by GPC-MALS method, and in this case, roll processability and banbury processability can be greatly improved without impairing the strength characteristics of the acrylic rubber sheet.

The glass transition temperature (Tg) of the acrylic rubber constituting the acrylic rubber sheet of the present invention can be appropriately selected depending on the purpose of use of the acrylic rubber, and is usually 20 ℃ or less, preferably 10 ℃ or less, more preferably 0 ℃ or less, and in this case, processability and cold resistance are excellent, and therefore, it is preferable. The lower limit of the glass transition temperature (Tg) of the acrylic rubber is not particularly limited, but is usually-80℃or higher, preferably-60℃or higher, and more preferably-40℃or higher. By setting the glass transition temperature to the lower limit or more, oil resistance and heat resistance can be further improved, and by setting the glass transition temperature to the upper limit or less, processability, crosslinkability and cold resistance can be further improved.

< acrylic rubber sheet >

The acrylic rubber sheet of the present invention is characterized by having the above ion-reactive group, preferably being formed of the above acrylic rubber, and having a specific gel amount.

The gel amount of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, and is preferably 30% by weight or less, more preferably 20% by weight or less, still more preferably 15% by weight or less, particularly preferably 10% by weight or less, and most preferably 5% by weight or less, based on the amount of methyl ethyl ketone insoluble component, and in this case, processability during kneading such as banbury is significantly improved. The acrylic rubber sheet of the present invention is preferably obtained by melt-kneading and drying the aqueous pellets produced in the coagulation reaction in a state (water content less than 1% by weight) after removing most of the water by a screw type biaxial extruder dryer, and in this case, the banbury processability and strength characteristics are highly balanced.

The ash content of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.3% by weight or less, particularly preferably 0.2% by weight or less, and most preferably 0.15% by weight or less, and in this range, strength characteristics and workability are highly balanced, and therefore, it is preferable.

The lower limit of the ash content of the acrylic rubber sheet of the present invention is not particularly limited and may be appropriately selected depending on the purpose of use, but is usually 0.0001 wt% or more, preferably 0.0005 wt% or more, more preferably 0.001 wt% or more, particularly preferably 0.005 wt% or more, and most preferably 0.01 wt% or more, and in this case, the metal adhesion of the rubber is reduced and the handleability is excellent, and therefore, the acrylic rubber sheet is preferable.

The ash content in the acrylic rubber sheet of the present invention is usually in the range of 0.0001 to 0.5 wt%, preferably 0.0005 to 0.3 wt%, more preferably 0.001 to 0.2 wt%, particularly preferably 0.005 to 0.15 wt%, and most preferably 0.01 to 0.13 wt% in the case where the water resistance, strength characteristics, workability and handleability are highly balanced.

The total amount of sodium, magnesium, calcium, phosphorus and sulfur in the ash of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more, and in this case, the water resistance of the acrylic rubber sheet is greatly improved, and is therefore preferred. In addition, when the total amount of sodium, magnesium, calcium, phosphorus and sulfur in the ash of the acrylic rubber sheet of the present invention falls within this range, the metal adhesion is reduced, and the handleability is excellent, so that it is preferable.

The total amount of magnesium and phosphorus in the ash of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more, and in this case, the water resistance, strength characteristics and workability of the acrylic rubber sheet are highly balanced and therefore preferable. When the total amount of magnesium and phosphorus in ash of the acrylic rubber sheet of the present invention falls within this range, the metal adhesion is reduced and the handleability is excellent, which is preferable.

The amount of magnesium in the ash of the acrylic rubber sheet of the present invention is not particularly limited and may be appropriately selected depending on the purpose of use, and is usually in the range of 10% by weight or more, preferably 15 to 60% by weight, more preferably 20 to 50% by weight, particularly preferably 25 to 45% by weight, and most preferably 30 to 40% by weight.

The amount of phosphorus in the ash of the acrylic rubber sheet of the present invention is not particularly limited and may be appropriately selected depending on the purpose of use, and is usually in the range of 10% by weight or more, preferably 20 to 90% by weight, more preferably 30 to 80% by weight, particularly preferably 40 to 70% by weight, and most preferably 50 to 60% by weight.

The ratio of magnesium to phosphorus ([ Mg ]/[ P ]) in ash of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually in the range of 0.4 to 2.5, preferably 0.45 to 1.2, more preferably 0.45 to 1, particularly preferably 0.5 to 0.8, and most preferably 0.55 to 0.7 in terms of weight ratio, and in this case, the water resistance, strength characteristics and workability of the acrylic rubber sheet are highly balanced, and thus are preferable.

Here, the ash in the acrylic rubber sheet mainly comes from an emulsifier used for emulsifying a monomer component and performing emulsion polymerization, and a coagulant used for coagulating an emulsion polymerization liquid, and the total ash amount, the content of magnesium and phosphorus in the ash, and the like are not only dependent on the conditions of the emulsion polymerization step and the coagulation step, but also vary depending on the respective conditions of the subsequent steps.

The acrylic rubber sheet of the present invention is preferably produced by using an anionic emulsifier, a cationic emulsifier or a nonionic emulsifier as an emulsifier in emulsion polymerization described later, and more preferably by using a phosphate or sulfate, and in this case, in addition to the water resistance and strength properties, the mold releasability and workability can be greatly improved. The water resistance of the acrylic rubber sheet is closely related to the ash content in the acrylic rubber and the total amount of sodium, magnesium, calcium, phosphorus and sulfur in the ash, but the use of the above-described emulsifier is preferable because the water resistance, strength characteristics, mold release and processing characteristics of the acrylic rubber sheet can be further highly balanced.

The acrylic rubber sheet of the present invention is preferably produced by using a metal salt, preferably an alkali metal salt or a metal salt of group 2 of the periodic table as a coagulant to be described later, and in this case, in addition to the water resistance and strength characteristics, mold releasability and workability can be greatly improved. The water resistance of the acrylic rubber sheet is closely related to the ash content in the acrylic rubber and the total amount of sodium, magnesium, calcium, phosphorus and sulfur in the ash, and the use of the above-described coagulant is preferable because the water resistance, strength characteristics, mold releasability and workability of the acrylic rubber sheet are further highly balanced.

The complex viscosity ([ eta ]60 ℃) of the acrylic rubber sheet of the present invention at 60℃is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually not more than 15000[ Pa.s ], preferably 1000 to 10000[ Pa.s ], more preferably 2000 to 5000[ Pa.s ], particularly preferably 2500 to 4000[ Pa.s ], and most preferably 2500 to 3000[ Pa.s ], and in this case, processability, oil resistance and shape retention are excellent, and therefore, it is preferable.

The complex viscosity ([ eta ]100 ℃) of the acrylic rubber sheet of the present invention at 100℃is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 1500 to 6000[ Pa.s ], preferably 2000 to 5000[ Pa.s ], more preferably 2300 to 4000[ Pa.s ], particularly preferably 2500 to 3500[ Pa.s ], and most preferably 2500 to 3000[ Pa.s ], and in this case, processability, oil resistance and shape retention are excellent, and therefore, it is preferable.

The ratio of the complex viscosity at 100 ℃ ([ eta ]100 ℃) to the complex viscosity at 60 ℃ ([ eta ]60 ℃) ([ eta ]100 ℃/[ eta ]60 ℃) of the acrylic rubber sheet of the present invention is not particularly limited, and is appropriately selected depending on the purpose of use, and is usually 0.5 or more, preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, and most preferably 0.83 or more. The ratio of the complex viscosity at 100 ℃ ([ eta ]100 ℃) to the complex viscosity at 60 ℃ ([ eta ]60 ℃) ([ eta ]100 ℃/[ eta ]60 ℃) of the acrylic rubber sheet of the present invention is not particularly limited, and is appropriately selected depending on the purpose of use, but is usually in the range of 0.5 to 0.99, preferably 0.6 to 0.98, more preferably 0.7 to 0.97, particularly preferably 0.8 to 0.96, and most preferably 0.85 to 0.95, and in this case, the processability, oil resistance and shape retention are highly balanced, and therefore, the acrylic rubber sheet is preferable.

The water content of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less, and in this case, the vulcanization characteristics of the acrylic rubber sheet are optimal, and the characteristics such as heat resistance and water resistance are significantly improved, and therefore, it is preferable.

The pH of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 6 or less, preferably 3 to 6, more preferably 3 to 5, and in this case, the storage stability of the acrylic rubber sheet is significantly improved, and is therefore preferable.

The Mooney viscosity (ML1+4, 100 ℃) of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, and is usually in the range of 10 to 150, preferably 20 to 100, more preferably 25 to 70, and in this case, the processability and strength characteristics of the acrylic rubber sheet are highly balanced and thus preferable.

The specific gravity of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 0.7 or more, preferably 0.8 or more, more preferably 0.9 or more, particularly preferably 0.95 or more, and most preferably 1 or more, and in this case, air is hardly present in the interior, and the storage stability is excellent, and therefore, it is preferable. The specific gravity of the acrylic rubber sheet of the present invention is usually in the range of 0.7 to 1.6, preferably 0.8 to 1.5, more preferably 0.9 to 1.4, particularly preferably 0.95 to 1.3, and most preferably 1.0 to 1.2, and in this case, productivity, storage stability, crosslinking property stability of the crosslinked product, and the like are highly balanced, and therefore, it is preferable. When the specific gravity of the acrylic rubber sheet is too small, it means that the amount of air mixed into the acrylic rubber sheet is large, and this is not preferable because it has a large influence on the storage stability including oxidative deterioration and the like.

The specific gravity of the acrylic rubber sheet of the present invention is the specific gravity obtained by dividing the mass by the volume including voids, that is, the specific gravity obtained by dividing the mass measured in air by the buoyancy, and is usually the specific gravity measured by the a method according to JIS K6268 crosslinked rubber-density measurement.

The acrylic rubber sheet of the present invention is not particularly limited as long as it is in the form of a sheet, and when it is a melt-kneaded sheet, it is preferable that the gel content of the methyl ethyl ketone-insoluble component is small, and the specific gravity measured by the JIS K6268A method is large, and the banbury processability and storage stability are particularly excellent.

The acrylic sheet of the present invention is preferably melt kneaded and dried, since the storage stability, roll processability, banbury processability, crosslinkability, water resistance, strength properties and compression set resistance are highly balanced. The acrylic rubber sheet is preferably produced by melt kneading and drying the aqueous pellets produced in the coagulation reaction in a state (water content less than 1% by weight) after most of the water is removed by a screw type biaxial extruder dryer, and in this case, the banbury processability and strength characteristics are highly balanced. Further, as the acrylic rubber sheet, it is preferable to dry the aqueous pellet produced in the coagulation reaction by a screw type biaxial extrusion dryer under reduced pressure or to melt-knead and dry under reduced pressure, because the characteristics of storage stability, roll processability and strength characteristics are particularly excellent and highly balanced.

The thickness of the acrylic rubber sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually in the range of 1 to 40mm, preferably 2 to 35mm, more preferably 3 to 30mm, and most preferably 5 to 25mm, and in this case, the handling property, storage stability and productivity are highly balanced, and therefore, it is preferable.

The width of the acrylic rubber sheet of the present invention may be appropriately selected depending on the purpose of use, and is usually in the range of 300 to 1200mm, preferably 400 to 1000mm, more preferably 500 to 800mm, and in this case, the operability is particularly excellent, and is therefore preferable.

The length of the acrylic rubber sheet of the present invention is not particularly limited, but is usually in the range of 300 to 1200mm, preferably 400 to 1000mm, more preferably 500 to 800mm, and in this case, the operability is particularly excellent, and thus is preferable.

< method for producing acrylic rubber sheet >

The method for producing the acrylic rubber sheet is not particularly limited, and for example, the acrylic rubber sheet can be efficiently produced by a method comprising the steps of: an emulsifying step of emulsifying an acrylic rubber monomer component containing an ion-reactive group-containing monomer with water and an emulsifier; an emulsion polymerization step of initiating a polymerization reaction in the presence of a redox catalyst comprising an inorganic radical generator and a reducing agent, adding a chain transfer agent after the batch during the polymerization, and continuing the polymerization to obtain an emulsion polymerization solution; a coagulation step of coagulating the emulsion polymerization liquid obtained with a coagulating liquid to produce an aqueous pellet; a cleaning step of cleaning the produced aqueous pellets; a dehydration step of dehydrating the washed aqueous pellets in a dehydration cylinder to a water content of 1 to 40 wt% using a dehydration cylinder having a dehydration slit, a dryer cylinder under reduced pressure, and a screw type biaxial extrusion dryer having a die at the tip; a drying step of drying in a dryer barrel to less than 1% by weight; and a step of extruding the sheet-like dry rubber from the die.

(monomer component)

The monomer component containing the ion-reactive group-containing monomer used in the present invention is not particularly limited, and a substance formed of at least one (meth) acrylate selected from the group consisting of an alkyl (meth) acrylate and an alkoxyalkyl (meth) acrylate, the ion-reactive group-containing monomer, and other monomers copolymerizable as necessary is preferable, and is the same as exemplified and preferable ranges of the monomer component already described. As already described, the amount of the monomer component used may be appropriately selected so that the composition of the acrylic rubber constituting the acrylic rubber sheet of the present invention becomes the composition in emulsion polymerization.

(emulsifier)

The emulsifier used in the present invention is not particularly limited, and examples thereof include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, and the like, and anionic emulsifiers are preferable.

The anionic emulsifier is not particularly limited, and examples thereof include: salts of fatty acids such as myristic acid, palmitic acid, oleic acid, and linolenic acid; alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; sulfate salts such as sodium lauryl sulfate, phosphate salts such as polyoxyalkylene alkyl ether phosphate salts; alkyl sulfosuccinates, and the like. Among these anionic emulsifiers, phosphate salts and sulfate salts are preferable, phosphate salts are particularly preferable, and dibasic phosphate salts are most preferable, since the water resistance, strength characteristics, mold releasability and workability of the obtained acrylic rubber sheet can be highly balanced. The phosphate and sulfate are preferably alkali metal salts of phosphate and sulfate, and more preferably sodium salts of phosphate and sulfate, and in this case, the water resistance, strength characteristics, mold release properties and workability of the obtained acrylic rubber sheet can be highly balanced, and thus are preferable.

The dibasic phosphate is not particularly limited as long as it can be used as an emulsifier in emulsion polymerization, and examples thereof include alkoxypolyoxyalkylene phosphate and alkylphenoxypolyoxyalkylene phosphate, and among them, metal salts thereof are preferable, alkali metal salts thereof are more preferable, and sodium salts thereof are most preferable.

Examples of the alkoxypolyoxyalkylene phosphate include alkoxypolyoxyethylene phosphate and alkoxypolyoxypropylene phosphate, and among these alkoxypolyoxyethylene phosphate is preferable.

As specific examples of the alkoxypolyoxyethylene phosphate salt, there may be mentioned octyloxydioxyethylene phosphate, octyloxytrioxyethylene phosphate, octyloxytetraethylene phosphate, decyloxy tetraethylene phosphate, dodecyloxytetraethylene phosphate, tridecyloxytetraethylene phosphate, tetradecyloxy tetraethylene phosphate, hexadecyloxy tetraethylene phosphate, octadecyl tetraethylene phosphate, octyloxypentaethylene phosphate, decyloxy pentaethylene phosphate, dodecyloxypentaethylene phosphate, tridecyloxypentaethylene phosphate, tetradecyloxy pentaethylene phosphate, hexadecyloxy pentaethylene phosphate, octadecyl pentaethylene phosphate, octyloxyhexaethylene phosphate, decyloxy hexaethylene phosphate, dodecyloxyhexaethylene phosphate, tridecyloxyhexaethylene phosphate, tetradecyloxy hexaethylene phosphate, hexadecyloxy hexaethylene phosphate, octadecyl hexaethylene phosphate, octooxyoctaethylene phosphate, dodecanoxyoctaethylene phosphate, trideoxyoctaethylene phosphate, octaalkoxyoctaalkoxyl octaethylene phosphate, and the alkali metal salts thereof are particularly preferred among them.

As specific examples of the alkoxypolyoxypropylene phosphate, there may be mentioned octyloxydioxy propylene phosphate, octyloxytrioxypropylene phosphate, octyloxytetraoxypropylene phosphate, decyloxy tetrapropenyl phosphate, dodecyloxytetrapropenyl phosphate, tridecyloxytetraoxypropenyl phosphate, tetradecyloxy tetrapropenyl phosphate, hexadecyloxy tetrapropenyl phosphate, octadecyloxypropenyl phosphate, octyloxypentaoxypropenyl phosphate, decyloxy pentapropenyl phosphate, dodecyloxypentaoxypropenyl phosphate, tridecyloxypentaoxypropenyl phosphate, tetradecyloxy pentapropenyl phosphate, hexadecyloxy pentapropenyl phosphate, octadecyloxypentaoxypropenyl phosphate, octyloxypropenyl phosphate, decyloxy hexaoxypropenyl phosphate, dodecyloxypropenyl phosphate, tridecyloxyhexaoxypropenyl phosphate, tetradecyloxy hexaoxypropenyl phosphate, hexadecyloxy hexaoxypropenyl phosphate, octadecyloxypropenyl phosphate, decyloxy octaoxypropenyl phosphate, dodecyloxypropenyl phosphate, tridecyloxyoctaoxypropenyl phosphate, octaalkoxyl octaoxypropenyl phosphate, octaalkoxyl phosphate, and octaalkoxyl phosphate, especially preferred among them are sodium salts thereof.

Specific examples of the alkylphenoxypolyoxyalkylene phosphate include alkylphenoxypolyoxyethylene phosphate and alkylphenoxypolyoxypropylene phosphate, and among these, alkylphenoxypolyoxyethylene phosphate is preferable.

Specific examples of the alkylphenoxypolyoxyethylene phosphate salt include metal salts such as methylphenoxy tetraoxyethylene phosphate, ethylphenoxytetraoxyethylene phosphate, butylphenoxy tetraoxyethylene phosphate, hexylphenoxy tetraoxyethylene phosphate, nonylphenoxy tetraoxyethylene phosphate, dodecylphenoxy tetraoxyethylene phosphate, octadecylphenoxy tetraoxyethylene phosphate, methylphenoxy pentaoxyethylene phosphate, ethylphenoxypentaoxyethylene phosphate, butylphenoxy pentaoxyethylene phosphate, hexylphenoxy pentaoxyethylene phosphate, nonylphenoxy pentaoxyethylene phosphate, dodecylphenoxy pentaoxyethylene phosphate, methylphenoxy hexaoxyethylene phosphate, ethylphenoxyhexaoxyethylene phosphate, butylphenoxy hexaoxyethylene phosphate, hexylphenoxy hexaoxyethylene phosphate, nonylphenoxy hexaoxyethylene phosphate, ethylphenoxyoctaoxyethylene phosphate, butylphenoxy octaoxyethylene phosphate, hexylphenoxy octaoxyethylene phosphate, dodecylphenoxy octaoxyethylene phosphate, and the like, and among them, sodium salts thereof are particularly preferable.

Specific examples of the alkylphenoxypolyoxypropylene phosphate include metal salts such as methylphenoxy tetrapropoxy phosphate, ethylphenoxy tetrapropoxy phosphate, butylphenoxy tetrapropoxy phosphate, hexylphenoxy tetrapropoxy phosphate, nonylphenoxy tetrapropoxy phosphate, dodecylphenoxy tetrapropoxy phosphate, methylphenoxy pentapropoxy phosphate, ethylphenoxy pentapropoxy phosphate, butylphenoxy pentapropoxy phosphate, hexylphenoxy pentapropoxy phosphate, nonylphenoxy pentapropoxy phosphate, dodecylphenoxy pentapropoxy phosphate, methylphenoxy hexaoxypropoxy phosphate, ethylphenoxy hexaoxypropoxy phosphate, butylphenoxy hexaoxyprop phosphate, hexylphenoxy hexaoxyprop phosphate, nonylphenoxy hexaoxyprop phosphate, dodecylphenoxy hexaoxyprop phosphate, methylphenoxy octaoxyprop phosphate, ethylphenoxy octaoxyprop phosphate, butylphenoxy octaoxyprop phosphate, hexylphenoxy octaoxyprop phosphate, nonylphenoxy octaoxyprop phosphate, dodecylphenoxy octaoxyprop phosphate, and the like, and alkali metal salts thereof are particularly preferred, and sodium salts thereof are particularly preferred.

As the phosphate ester salt, a mono-phosphate ester salt such as a sodium salt of di (alkoxypolyoxyalkylene) phosphate ester can be used alone or in combination with a di-phosphate ester salt.

Examples of the sulfate salt include sodium lauryl sulfate, potassium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, sodium polyoxyethylene alkyl sulfate, sodium polyoxyethylene alkylaryl sulfate, and the like, with sodium lauryl sulfate being preferred.

Examples of the cationic emulsifier include alkyl trimethyl ammonium chloride, dialkyl ammonium chloride, benzyl ammonium chloride, and the like.

Examples of the nonionic emulsifier include: polyoxyalkylene fatty acid esters such as polyoxyethylene stearate; polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether; polyoxyalkylene alkylphenol ethers such as polyoxyethylene nonylphenyl ether; the polyoxyethylene sorbitan alkyl ester is preferably a polyoxyalkylene alkyl ether or a polyoxyalkylene alkylphenol ether, and more preferably a polyoxyethylene alkyl ether or a polyoxyethylene alkylphenol ether.

These emulsifiers may be used alone or in combination of 2 or more, and the amount thereof is usually in the range of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 1 to 3 parts by weight, relative to 100 parts by weight of the monomer component.

The method (mixing method) of mixing the monomer component, water and emulsifier may be a conventional method, and examples thereof include: a method of stirring the monomer, the emulsifier and the water using a stirrer such as a homogenizer or a disk turbine (disk turbine). The amount of water to be used is usually in the range of 1 to 1000 parts by weight, preferably 5 to 500 parts by weight, more preferably 4 to 300 parts by weight, particularly preferably 3 to 150 parts by weight, and most preferably 20 to 80 parts by weight, relative to 100 parts by weight of the monomer component.

(inorganic radical generator)

As the polymerization catalyst used in the present invention, a redox catalyst formed of an inorganic radical generator and a reducing agent is used. In particular, the use of an inorganic radical generator is preferable because the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic rubber can be widened and the processability of the produced acrylic rubber sheet such as a roll can be greatly improved.

The inorganic radical generator is not particularly limited as long as it is an inorganic radical generator generally used in emulsion polymerization, and examples thereof include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, hydrogen peroxide, and the like, and among them, persulfates are preferable, potassium persulfate and ammonium persulfate are more preferable, and potassium persulfate is particularly preferable.

These inorganic radical generators may be used alone or in combination of 2 or more kinds, and the amount thereof is usually in the range of 0.0001 to 5 parts by weight, preferably 0.0005 to 1 part by weight, more preferably 0.001 to 0.25 part by weight, particularly preferably 0.01 to 0.21 part by weight, and most preferably 0.1 to 0.2 part by weight, relative to 100 parts by weight of the monomer component.

(reducing agent)

The reducing agent used in the present invention is not particularly limited as long as it is a reducing agent generally used in emulsion polymerization, and it is preferable to use at least 2 reducing agents, and it is preferable to combine a metal ion compound in a reduced state and the other reducing agents because the banbury processability, roll processability and strength characteristics of the obtained acrylic rubber sheet can be further highly balanced.

The metal ion compound in the reduced state is not particularly limited, and examples thereof include ferrous sulfate, sodium iron hexamethylenediamine tetraacetate, cuprous naphthenate, and the like, and among them, ferrous sulfate is preferable. These metal ion compounds in a reduced state may be used singly or in combination of 2 or more, and the amount thereof is usually in the range of 0.000001 to 0.01 part by weight, preferably 0.00001 to 0.001 part by weight, more preferably 0.00005 to 0.0005 part by weight, relative to 100 parts by weight of the monomer component.

The reducing agent other than the metal ion compound in the reduced state used in the present invention is not particularly limited, and examples thereof include: ascorbic acid or its salt such as ascorbic acid, sodium ascorbate, potassium ascorbate, etc.; erythorbic acid or salts thereof such as erythorbic acid, sodium erythorbate, potassium erythorbate, and the like; sulfinate salts such as sodium hydroxymethanesulfinate; sulfite such as sodium sulfite, potassium sulfite, sodium bisulfite, sodium aldehyde bisulfite, and potassium bisulfite; metabisulfites such as sodium metabisulfite, potassium metabisulfite and the like; thiosulfate such as sodium thiosulfate and potassium thiosulfate; phosphorous acid such as phosphorous acid, sodium phosphite, potassium phosphite, sodium hydrogen phosphite, potassium hydrogen phosphite, or salts thereof; pyrophosphorotic acid such as pyrophosphorotic acid, sodium pyrophosphate, potassium pyrophosphate, sodium hydrogen pyrophosphate, potassium hydrogen pyrophosphate, etc., or salts thereof; sodium formaldehyde sulfoxylate and the like. Among them, ascorbic acid or a salt thereof, sodium formaldehyde sulfoxylate and the like are preferable, and ascorbic acid or a salt thereof is particularly preferable.

These reducing agents other than the metal ion compound in the reduced state may be used singly or in combination of 2 or more, and the amount thereof is usually in the range of 0.001 to 1 part by weight, preferably 0.005 to 0.5 part by weight, more preferably 0.01 to 0.1 part by weight, relative to 100 parts by weight of the monomer component.

A preferred combination of the metal ion compound in the reduced state and the other reducing agent is a combination of ferrous sulfate with ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate, more preferably a combination of ferrous sulfate with ascorbic acid or a salt thereof. In this case, the amount of the ferrous sulfate to be used is usually in the range of 0.000001 to 0.01 parts by weight, preferably 0.00001 to 0.001 parts by weight, more preferably 0.00005 to 0.0005 parts by weight, and the amount of the ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate to be used is usually in the range of 0.001 to 1 part by weight, preferably 0.005 to 0.5 parts by weight, more preferably 0.01 to 0.1 part by weight, per 100 parts by weight of the monomer component.

The amount of water used in the emulsion polymerization may be only that used in the emulsification of the monomer component, or may be adjusted so that the amount of water used is usually in the range of 10 to 1000 parts by weight, preferably 50 to 500 parts by weight, more preferably 80 to 400 parts by weight, and most preferably 100 to 300 parts by weight, relative to 100 parts by weight of the monomer component used for the polymerization.

The emulsion polymerization may be carried out by a conventional method, and may be carried out in any of batch, semi-batch, and continuous modes. The polymerization temperature and polymerization time are not particularly limited, and may be appropriately selected depending on the kind of the polymerization initiator used, and the like. The polymerization time is usually 0.5 to 100 hours, preferably 1 to 10 hours.

The emulsion polymerization is exothermic, and if not controlled, the temperature is increased to shorten the polymerization reaction, and in the present invention, the emulsion polymerization temperature is usually controlled to 35℃or less, preferably 0 to 35℃and more preferably 5 to 30℃and particularly preferably 10 to 25℃and the strength characteristics of the produced acrylic rubber sheet are preferably highly balanced with the processability in kneading by a Banbury mixer or the like.

(post addition of chain transfer agent)

The present invention is characterized in that it is preferable to add the chain transfer agent in the initial stage in a batch manner and then in the polymerization process, because it is possible to produce an acrylic rubber having a high molecular weight component separated from a low molecular weight component and the strength characteristics of the produced acrylic rubber sheet and the processability at the time of kneading by rolls or the like are highly balanced.

The chain transfer agent to be used is not particularly limited as long as it is a chain transfer agent generally used in emulsion polymerization, and for example, a thiol compound can be preferably used.

As the thiol compound, an alkyl thiol compound having 2 to 20 carbon atoms can be generally used, and an alkyl thiol compound having 5 to 15 carbon atoms is preferably used, and an alkyl thiol compound having 6 to 14 carbon atoms is more preferably used.

The alkyl thiol compound may be any of an n-alkyl thiol compound, a secondary alkyl thiol compound, and a tertiary alkyl thiol compound, and is preferably an n-alkyl thiol compound or a tertiary alkyl thiol compound, and more preferably an n-alkyl thiol compound, and in this case, the effect of the chain transfer agent can be stably exhibited, and the processability of the produced acrylic rubber such as rollers can be significantly improved.

Specific examples of the alkylthiol compound include n-pentylmercaptan, n-hexylthiol, n-heptylthiol, n-octylthiol, n-decylthiol, n-dodecylthiol, n-tridecylthiol, n-tetradecylthiol, n-hexadecylthiol, n-octadecylthiol, sec-pentylmercaptan, sec-hexylthiol, zhong Geng thiol, zhong Xin thiol, zhong Gui thiol, sec-dodecylthiol, sec-tridecylthiol, sec-tetradecylthiol, sec-hexadecylthiol, sec-octadecylthiol, tert-pentylmercaptan, tert-hexylthiol, tert-heptylthiol, tert-octylthiol, tert-decylthiol, tert-dodecylthiol, tert-tridecylthiol, tert-tetradecylthiol, tert-hexadecylthiol, tert-octadecylthiol, and the like, preferably n-octylthiol, n-dodecylthiol, tert-dodecylthiol, more preferably n-octylthiol, and n-dodecylthiol.

These chain transfer agents can be used singly or in combination of 2 or more kinds. The amount of the chain transfer agent used is not particularly limited, but is usually in the range of 0.0001 to 1 part by weight, preferably 0.0005 to 0.5 part by weight, more preferably 0.001 to 0.5 part by weight, particularly preferably 0.005 to 0.1 part by weight, and most preferably 0.01 to 0.06 part by weight, based on 100 parts by weight of the monomer component, and in this case, the strength characteristics and roll processability of the produced acrylic rubber sheet are highly balanced, and thus are preferable.

The present invention is characterized in that the high molecular weight component and the low molecular weight component of the obtained acrylic rubber can be produced by adding the chain transfer agent in a batch manner during the polymerization without adding the chain transfer agent at the initial stage of the polymerization, and the molecular weight distribution is in a specific range, so that the strength characteristics of the acrylic rubber sheet and the processability of rolls and the like can be highly balanced, and therefore, it is preferable.

The number of times of adding the chain transfer agent after the batch is not particularly limited, and may be appropriately selected depending on the purpose of use, and is usually 1 to 5 times, preferably 2 to 4 times, more preferably 2 to 3 times, and particularly preferably 2 times, and in this case, the strength characteristics of the produced acrylic rubber sheet and the workability of rolls and the like can be highly balanced, and thus are preferable.

The time for starting the batch-wise post-addition of the chain transfer agent is not particularly limited, and may be appropriately selected depending on the purpose of use, and is generally preferably in the range of from 35 to 150 minutes, most preferably 40 to 120 minutes, after 20 minutes, preferably 30 minutes, more preferably 30 to 200 minutes, and most preferably 35 to 150 minutes, from the initiation of the polymerization, and in this case, the strength characteristics of the produced acrylic rubber sheet and the workability of the roll and the like can be highly balanced.

When the chain transfer agent is added after the batch, the amount to be added per one time is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually in the range of 0.00005 to 0.5 part by weight, preferably 0.0001 to 0.1 part by weight, more preferably 0.0005 to 0.05 part by weight, particularly preferably 0.001 to 0.03 part by weight, and most preferably 0.002 to 0.02 part by weight, based on 100 parts by weight of the monomer component, and in this case, the strength characteristics and roll processability of the produced acrylic rubber sheet can be highly balanced, and thus it is preferable.

The polymerization reaction can be continued for usually 30 minutes or longer, preferably 45 minutes or longer, and more preferably 1 hour or longer, without any particular limitation after the addition of the chain transfer agent.

(post addition of reducing agent)

In the present invention, the reducing agent of the above-mentioned redox catalyst can be added later in the polymerization process, and thus the strength characteristics of the produced acrylic rubber sheet and the workability of rolls and the like can be highly balanced, and thus it is preferable.

The reducing agent added after the polymerization reaction is the same as the above-mentioned examples and preferable ranges of the reducing agent. In the present invention, as the reducing agent to be added later, ascorbic acid or a salt thereof is preferable.

The amount of the reducing agent to be added after the polymerization is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually in the range of 0.0001 to 1 part by weight, preferably 0.0005 to 0.5 part by weight, more preferably 0.001 to 0.5 part by weight, particularly preferably 0.005 to 0.1 part by weight, and most preferably 0.01 to 0.05 part by weight, based on 100 parts by weight of the monomer component, and in this case, the productivity of the produced acrylic rubber is excellent and the strength characteristics and processability of the produced acrylic rubber sheet can be highly balanced, and thus it is preferable.

The reducing agent added later in the polymerization process may be added continuously or batchwise, preferably batchwise. The number of times when the reducing agent is added after the batch in the polymerization process is not particularly limited, but is usually 1 to 5 times, preferably 1 to 3 times, more preferably 1 to 2 times.

When the reducing agent added at the beginning of polymerization and during the polymerization is ascorbic acid or a salt thereof, the ratio of the amount of the ascorbic acid or a salt thereof added at the beginning to the amount of the ascorbic acid or a salt thereof added at the later is not particularly limited, and is usually in the range of 1/9 to 8/2, preferably 2/8 to 6/4, more preferably 3/7 to 5/5, based on the weight ratio of "the ascorbic acid or a salt thereof added at the beginning"/"the ascorbic acid or a salt thereof added after batchwise", in this case, the productivity of the acrylic rubber is excellent and the strength characteristics and the workability of the produced acrylic rubber sheet can be highly balanced, and therefore, it is preferable.

The timing of post-addition of the reducing agent is not particularly limited, and may be appropriately selected depending on the purpose of use, and is usually in the range of 1 to 3 hours, more preferably 1.5 to 2.5 hours after initiation of polymerization, from the initiation of polymerization, and in this case, the productivity of the produced acrylic rubber is excellent and the strength characteristics of the produced acrylic rubber sheet and the workability of rolls and the like can be highly balanced, and thus is preferable.

When the reducing agent is added after the batch, the amount to be added per one time is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually in the range of 0.00005 to 0.5 part by weight, preferably 0.0001 to 0.1 part by weight, more preferably 0.0005 to 0.05 part by weight, particularly preferably 0.001 to 0.03 part by weight, based on 100 parts by weight of the monomer component, and in this case, the strength characteristics of the produced acrylic rubber sheet and the workability of rolls and the like can be highly balanced, and thus are preferable.

The operation after the addition of the reducing agent is not particularly limited, and the polymerization reaction is usually continued for 30 minutes or more, preferably 45 minutes or more, more preferably 1 hour or more and ended.

The polymerization conversion rate of the emulsion polymerization is preferably 90% by weight or more, more preferably 95% by weight or more, and in this case, the produced acrylic rubber sheet is excellent in strength characteristics and free from monomer odor. In terminating the polymerization, a polymerization terminator may also be used.

(coagulation step)

The coagulation step in the method for producing an acrylic rubber sheet of the present invention is a step of coagulating the emulsion polymerization liquid after emulsion polymerization with a coagulation liquid to produce an aqueous pellet.

The solid content concentration of the emulsion polymerization liquid used in the coagulation reaction is not particularly limited, and is usually adjusted to be in the range of 5 to 50% by weight, preferably 10 to 45% by weight, more preferably 20 to 40% by weight.

The coagulant of the coagulant liquid to be used is not particularly limited, and a metal salt is usually used. The metal salt may be, for example, an alkali metal, a metal salt of group 2 of the periodic table, or other metal salt, and is preferably an alkali metal salt, or a metal salt of group 2 of the periodic table, more preferably a metal salt of group 2 of the periodic table, and particularly preferably a magnesium salt, and in this case, the water resistance, strength characteristics, mold releasability, and workability of the resulting acrylic rubber sheet can be highly balanced, and thus are preferable.

Examples of the alkali metal salt include sodium salts such as sodium chloride, sodium nitrate, and sodium sulfate; potassium salts such as potassium chloride, potassium nitrate, and potassium sulfate; among these, sodium salts are preferable, and sodium chloride and sodium sulfate are particularly preferable.

Examples of the metal salt of group 2 of the periodic table include magnesium chloride, calcium chloride, magnesium nitrate, calcium nitrate, magnesium sulfate, and calcium chloride and magnesium sulfate are preferable.

Examples of the other metal salt include zinc chloride, titanium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, aluminum chloride, tin chloride, zinc nitrate, titanium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, aluminum nitrate, tin nitrate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate, and tin sulfate.

These coagulants may be used alone or in combination of 2 or more, and the amount thereof is usually in the range of 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight, more preferably 1 to 30 parts by weight, relative to 100 parts by weight of the monomer component. When the coagulant is in this range, the acrylic rubber can be sufficiently coagulated, and when the acrylic rubber sheet is crosslinked, compression set resistance and water resistance can be improved to a high degree, which is preferable.

The coagulant used is usually used as an aqueous solution, and the concentration of the coagulant in the aqueous solution is usually in the range of 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, and particularly preferably 1.5 to 5% by weight, and in this case, the particle size of the resulting aqueous aggregates can be uniformly concentrated in a specific region, which is preferable.

The temperature of the coagulating liquid is not particularly limited, but is usually 40℃or higher, preferably 40 to 90℃and more preferably 50 to 80℃and, in this case, uniform aqueous pellets can be produced, which is preferable.

The method of solidifying the emulsion polymerization liquid with the coagulant is not particularly limited, and for example, any one of a method of adding the coagulant to the emulsion polymerization liquid, a method of adding the coagulant to the stirred emulsion polymerization liquid, a method of adding the emulsion polymerization liquid to the coagulant, a method of adding the emulsion polymerization liquid to the stirred coagulant liquid, and the like may be used, and the method of adding the emulsion polymerization liquid to the stirred coagulant liquid is preferable because the washing efficiency and the dewatering efficiency of the produced aqueous pellets can be excellent, and the water resistance and the storage stability of the obtained acrylic rubber sheet can be remarkably improved.

The stirring number (rotation speed) of the stirred coagulation liquid, that is, the rotation speed of the stirring blade of the stirring device is not particularly limited, and is usually 100rpm or more, preferably 200rpm or more, more preferably 200 to 1000rpm, particularly preferably 300 to 900rpm, and most preferably 400 to 800 rpm.

Since the particle size of the produced aqueous pellets can be made small and uniform when the rotational speed is a rotational speed at which stirring is intense to some extent, it is preferable that the rotational speed is not less than the lower limit, and the particle size of the produced pellets is suppressed from being excessively large or excessively small, and the coagulation reaction can be controlled more easily by the rotational speed being not more than the upper limit.

The peripheral speed of the stirred coagulation liquid, that is, the speed of the outer periphery of the stirring blade of the stirring device is not particularly limited, and when the stirring is vigorously performed to a certain extent, the particle size of the resulting aqueous aggregates can be made small and uniform, and therefore, it is preferably usually 0.5m/s or more, preferably 1m/s or more, more preferably 1.5m/s or more, particularly preferably 2m/s or more, and most preferably 2.5m/s or more. On the other hand, the upper limit of the peripheral speed is not particularly limited, but is usually 50m/s or less, preferably 30m/s or less, more preferably 25m/s or less, and most preferably 20m/s or less, and in this case, the coagulation reaction is easily controlled, and is therefore preferable.

By setting the above-mentioned conditions of the coagulation reaction (contact method, solid content concentration of emulsion polymerization liquid, concentration and temperature of coagulation liquid, rotational speed and peripheral speed at the time of stirring coagulation liquid, etc.) in a specific range, the shape and pellet diameter of the produced aqueous pellets can be made uniform and concentrated, and the removal of the emulsifier and coagulant at the time of washing and dehydration can be significantly improved, and as a result, the water resistance and storage stability of the produced acrylic rubber sheet can be significantly improved, which is preferable.

(cleaning step)

The cleaning step in the method for producing an acrylic rubber sheet of the present invention is a step of cleaning the aqueous pellet produced in the coagulation reaction.

The washing method is not particularly limited, and can be performed by mixing the produced aqueous pellets with a large amount of water.

The amount of water to be added for cleaning is not particularly limited, but is preferably 50 parts by weight or more, preferably 50 to 15000 parts by weight, more preferably 100 to 10000 parts by weight, and still more preferably 500 to 5000 parts by weight per 100 parts by weight of the monomer component, and in this case, the ash content in the acrylic rubber sheet can be effectively reduced.

The temperature of the water to be used is not particularly limited, but it is preferably hot water, usually 40 ℃ or higher, preferably 40 to 100 ℃, more preferably 50 to 90 ℃, particularly preferably 60 to 80 ℃, and in this case, the cleaning efficiency can be significantly improved. By setting the temperature of the water to be used to be equal to or higher than the lower limit, the emulsifier and the coagulant can be separated from the aqueous pellet, thereby further improving the cleaning efficiency.

The washing time is not particularly limited, but is usually in the range of 1 to 120 minutes, preferably 2 to 60 minutes, more preferably 3 to 30 minutes.

The number of times of washing (water washing) is also not particularly limited, and is usually 1 to 10 times, preferably 1 to 5 times, more preferably 2 to 3 times. In addition, from the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber sheet, it is desirable that the number of times of washing is large, and the number of times of washing can be significantly reduced by setting the shape of the aqueous aggregates and the particle size of the aqueous aggregates to a specific range and/or setting the washing temperature to the above-described range as described above.

(Water removal Process)

In the present invention, it is preferable to provide a water removal step of separating free water from the washed hydrous pellets by a water remover, because the water removal efficiency can be improved.

The dewatering machine is not particularly limited, and a known dewatering machine can be used, and examples thereof include a wire mesh, a screen, an electric screen, and the like, and a wire mesh and a screen are preferable.

The mesh of the dewatering machine is not particularly limited, but is usually in the range of 0.01 to 5mm, preferably 0.1 to 1mm, more preferably 0.2 to 0.6mm, and in this case, the loss of the aqueous pellets is small and water can be efficiently removed, so that it is preferable.

The water content of the dehydrated hydrous pellets, that is, the water content of the hydrous pellets subjected to the dehydration and drying step is not particularly limited, but is usually in the range of 50 to 80% by weight, preferably 50 to 70% by weight, more preferably 50 to 60% by weight.

The temperature of the aqueous pellet after the water removal, that is, the temperature of the aqueous pellet subjected to the dehydration, drying and molding step is not particularly limited, but is usually 40 ℃ or higher, preferably 40 to 100 ℃, more preferably 50 to 90 ℃, particularly preferably 55 to 85 ℃, and most preferably 60 to 80 ℃, and in this case, it is preferable to efficiently dehydrate and dry the aqueous pellet having a specific heat of up to 1.5 to 2.5KJ/kg·k, which is difficult to raise the temperature, such as the acrylic rubber constituting the acrylic rubber sheet of the present invention, using a screw type biaxial extrusion dryer.

(dehydration, drying and Molding Process)

The dehydration, drying and molding steps in the method for producing an acrylic rubber sheet of the present invention are the following steps: the above-mentioned washed, preferably dehydrated, aqueous pellets are dehydrated to a water content of 1 to 40% by weight with a dehydration barrel, a dryer barrel under reduced pressure, and a screw type biaxial extrusion dryer having a die at the tip end, and then dried to less than 1% by weight with the dryer barrel, and a sheet-like dried rubber is extruded from the die.

(dehydration of the aqueous pellets with a dehydrator barrel)

The dehydration of the aqueous pellets was carried out with a dehydration barrel in a screw type twin-screw extrusion dryer having a dehydration slit. The mesh size of the dewatering slit may be appropriately selected depending on the conditions of use, but is usually in the range of 0.01 to 5mm, preferably 0.1 to 1mm, more preferably 0.2 to 0.6mm, and in this case, the loss of the aqueous pellets is small and the aqueous pellets can be efficiently dewatered, so that it is preferable.

The number of the dehydration cylinders in the screw type biaxial extrusion dryer is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 6, and in this case, it is preferable to dehydrate the adhesive acrylic rubber efficiently.

The removal of water from the aqueous pellets in the dewatering barrel can be performed by both removing water in a liquid state (draining) from the dewatering slit and removing water in a vapor state (draining), and in the present invention, draining is defined as dewatering, and draining is defined as predrying.

In the dehydration of the hydrous pellets, the water discharged from the dehydration slit may be in any of a liquid state (drainage) and a vapor state (vapor discharge), and in the case of dehydration using a screw type biaxial extrusion dryer having a plurality of dehydration barrels, it is preferable to efficiently dehydrate the adhesive acrylic rubber by combining drainage and vapor discharge. The selection of the water-discharge type dehydrator cylinder and the steam-discharge type dehydrator cylinder of the screw type biaxial extrusion dryer having 3 or more dehydrator cylinders can be appropriately performed according to the purpose of use, and generally, the water-discharge type cylinder is increased when the ash content in the produced acrylic rubber sheet is reduced, and the steam-discharge type cylinder is increased when the water content is reduced.

The setting temperature of the dehydration barrel may be appropriately selected depending on the monomer composition, ash amount, water content, operation conditions and the like of the acrylic rubber, and is usually in the range of 60 to 150 ℃, preferably 70 to 140 ℃, more preferably 80 to 130 ℃. The setting temperature of the dehydration barrel for dehydration in a drained state is usually 60 to 120 ℃, preferably 70 to 110 ℃, more preferably 80 to 100 ℃. The set temperature of the dehydration barrel for dehydration in the vapor-exhausted state is usually in the range of 100 to 150 ℃, preferably 105 to 140 ℃, and more preferably 110 to 130 ℃.

The water content after dehydration of the drainage type for extruding water from the hydrous pellets is not particularly limited, and may be 1 to 40% by weight, preferably 5 to 40% by weight, more preferably 5 to 35% by weight, particularly preferably 10 to 35% by weight, and in this case, productivity and ash removal efficiency are highly balanced, and thus preferable.

When the acrylic rubber having the tackiness of the reactive group is dehydrated by using a centrifuge or the like, the acrylic rubber adheres to the dehydration slit portion, and is hardly dehydrated (to a water content of about 45 to 55% by weight), and in the present invention, the water content can be reduced to the above range by using a screw type biaxial extrusion dryer having a dehydration slit and forcibly extruding with a screw.

For dehydration of the aqueous pellets in the case of having a water-draining type dehydrator cylinder and a steam-draining type dehydrator cylinder, the water content after water draining in the water-draining type dehydrator cylinder is usually 5 to 40% by weight, preferably 10 to 40% by weight, more preferably 15 to 35% by weight, and the water content after pre-drying in the steam-draining type dehydrator cylinder is usually 1 to 30% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight.

By setting the water content after dehydration to the above lower limit or more, the dehydration time can be shortened, deterioration of the acrylic rubber can be suppressed, and by setting the water content to the above upper limit or less, the ash content can be sufficiently reduced.

(drying of aqueous pellets in the dryer barrel section)

It is desirable to dry the dehydrated aqueous pellets by a screw type biaxial extrusion dryer having a dryer barrel portion under reduced pressure. The acrylic rubber is preferably dried under reduced pressure, because the drying efficiency is improved, and an acrylic rubber bag having a large specific gravity and excellent storage stability can be produced by removing air existing in the acrylic rubber. In the present invention, the acrylic rubber is melted and extrusion-dried under reduced pressure, whereby the storage stability can be greatly improved. The storage stability of the acrylic rubber sheet is largely related to the specific gravity of the acrylic rubber sheet, and can be controlled, and in the case of controlling the specific gravity and the high storage stability, the degree of pressure reduction in the extrusion drying can be controlled.

The degree of decompression of the dryer barrel may be appropriately selected, and is usually 1 to 50kPa, preferably 2 to 30kPa, more preferably 3 to 20kPa, and in this case, it is preferable to be able to dry the aqueous pellets efficiently, and to be able to remove air from the acrylic rubber, and to significantly improve the storage stability of the acrylic rubber bag.

The setting temperature of the dryer barrel may be appropriately selected, and is usually in the range of 100 to 250 ℃, preferably 110 to 200 ℃, more preferably 120 to 180 ℃, and in this case, it is preferable to reduce the gel amount in the acrylic rubber sheet while enabling efficient drying without scorching or deterioration of the acrylic rubber.

The number of the dryer cylinders in the screw type biaxial extrusion dryer is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 8. The degree of reduced pressure in the case of having a plurality of dryer cylinders may be similar or may be changed in all of the dryer cylinders. The set temperature in the case of having a plurality of dryer cylinders may be set to be similar to or variable from the temperature in all of the dryer cylinders, and it is preferable to increase the working efficiency by making the temperature of the discharge portion (near the die) higher than the temperature of the introduction portion (near the dryer cylinder).

The moisture content of the dried rubber after drying is usually less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less. In the present invention, in particular, the water content of the dried rubber in the screw type biaxial extrusion dryer is preferably set to the above value (almost water-removed state) and melt kneading and extrusion are performed, so that the gel content of the methyl ethyl ketone-insoluble component of the acrylic rubber sheet can be reduced. In the present invention, it is preferable to use a screw type biaxial extruder dryer for melt kneading or to highly balance the strength characteristics and the Banbury processability of the acrylic rubber sheet after melt kneading and drying. In the present invention, "melt kneading" or "melt kneading and drying" means kneading (mixing) in a molten state in a screw type biaxial extrusion dryer, extruding in a molten state, drying at this stage, or kneading, extruding and drying an acrylic rubber in a molten (plasticized) state by a screw type biaxial extrusion dryer.

In the present invention, the shear rate applied to the acrylic rubber in a substantially water-free state in the dryer barrel of the screw type biaxial extrusion dryer is not particularly limited, but is usually 10[1/s ] or more, preferably 10 to 400[1/s ], more preferably 50 to 250[1/s ], and in this case, the storage stability, roll processability, banbury processability, strength characteristics and compression set resistance of the obtained acrylic rubber sheet are highly balanced and therefore preferable.

The shear viscosity of the acrylic rubber in the dryer barrel of the screw type biaxial extrusion dryer used in the present invention, particularly in the dryer barrel, is not particularly limited, but is usually not more than 12000[ pa·s ], preferably 1000 to 12000[ pa·s ], more preferably 2000 to 10000[ pa·s ], particularly preferably 3000 to 7000[ pa·s ], and most preferably 4000 to 6000[ pa·s ], and in this case, the storage stability, roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet are highly balanced, and therefore preferred.

(extrusion of dried rubber from die head)

The dried rubber dehydrated and dried in the screw sections of the dehydrator cylinder and the dryer cylinder is fed to a rectifying die section without a screw, and extruded from the die section into a desired shape. The perforated plate and the metal mesh may or may not be provided between the screw portion and the die portion.

The die is preferably formed in a substantially rectangular shape, so that the extruded dry rubber is formed into a sheet shape, and a dry rubber having a small air-mixing amount, a large specific gravity, and excellent storage stability is obtained. In the die section, it is particularly important that the acrylic rubber melt-kneaded without air is extruded directly into a sheet without air.

The resin pressure of the die head is not particularly limited, but is usually in the range of 0.1 to 10Mpa, preferably 0.5 to 5Mpa, more preferably 1 to 3Mpa, and in this case, the acrylic rubber sheet is preferable because air inclusion is small (high specific gravity) and productivity is excellent.

Screw type biaxial extrusion dryer and operating conditions

The screw length (L) of the screw type biaxial extrusion dryer to be used may be appropriately selected depending on the purpose of use, and is usually in the range of 3000 to 15000mm, preferably 4000 to 10000mm, more preferably 4500 to 8000 mm.

The screw diameter (D) of the screw type biaxial extrusion dryer to be used may be appropriately selected depending on the purpose of use, and is usually in the range of 50 to 250mm, preferably 100 to 200mm, more preferably 120 to 160 mm.

The ratio (L/D) of the screw length (L) to the screw diameter (D) of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually in the range of 10 to 100, preferably 20 to 80, more preferably 30 to 60, and in this case, the water content can be preferably made to be less than 1% by weight without causing a decrease in the molecular weight or scorch of the dried rubber.

The rotational speed (N) of the screw type biaxial extrusion dryer to be used may be appropriately selected depending on the respective conditions, and is usually 10 to 1000rpm, preferably 50 to 750rpm, more preferably 100 to 500rpm, and most preferably 120 to 300rpm, and in this case, the water content and the gel amount of the acrylic rubber sheet can be efficiently reduced, which is preferable.

The extrusion amount (Q) of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually in the range of 100 to 1500 kg/hr, preferably 300 to 1200 kg/hr, more preferably 400 to 1000 kg/hr, and most preferably 500 to 800 kg/hr.

The ratio (Q/N) of the extrusion amount (Q) to the rotation speed (N) of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually in the range of 2 to 10, preferably 3 to 8, more preferably 4 to 6.

In the present invention, particularly, it is preferable to dry the aqueous pellets under high shear conditions by using a screw type biaxial extrusion dryer having two screws, because the roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet can be highly balanced.

The maximum torque of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually 25 N.m or more, preferably 30 N.m or more, more preferably 35 N.m or more, and particularly preferably 40 N.m or more. Further, the maximum torque of the screw type biaxial extrusion dryer used in the present invention is usually 25 to 125n·m, preferably 30 to 100n·m, more preferably 35 to 75n·m, particularly preferably 40 to 60n·m, and in this case, the roll processability, banbury processability and strength characteristics of the produced acrylic rubber sheet can be highly balanced, and thus it is preferable.

The specific energy consumption of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually 0.1 to 0.25[ kw.h/kg ] or more, preferably 0.13 to 0.23[ kw.h/kg ], and more preferably 0.15 to 0.2[ kw.h/kg ], and in this case, the roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet are highly balanced, and therefore, it is preferable.

The specific power of the screw type biaxial extrusion dryer to be used is not particularly limited, but is usually 0.2 to 0.6[ A.multidot.h/kg ] or more, preferably 0.25 to 0.55[ A.multidot.h/kg ], and more preferably 0.35 to 0.5[ A.multidot.h/kg ], and in this case, the roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet are highly balanced, and therefore, it is preferable.

The shear rate of the screw type biaxial extrusion dryer used is not particularly limited, but is usually 40 to 150[1/s ] or more, preferably 45 to 125[1/s ], and more preferably 50 to 100[1/s ], and in this case, the storage stability, roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet are highly balanced, and therefore preferable.

The shear viscosity of the acrylic rubber in the screw-type biaxial extrusion dryer to be used is not particularly limited, but is usually 4000 to 8000[ Pa.s ], preferably 4500 to 7500[ Pa.s ], more preferably 5000 to 7000[ Pa.s ], and in this case, the storage stability, roll processability, banbury processability and strength characteristics of the obtained acrylic rubber sheet are highly balanced and therefore preferable.

(sheet-like Dry rubber)

The shape of the dried rubber extruded from the screw type biaxial extrusion dryer is preferably a sheet, since the specific gravity can be made large without mixing air, and the storage stability can be greatly improved. The sheet-like dry rubber extruded from the screw type biaxial extrusion dryer is generally cooled and cut to be used as a rubber sheet.

The thickness of the sheet-like dry rubber extruded from the screw type biaxial extrusion dryer is not particularly limited, but is usually in the range of 1 to 40mm, preferably 2 to 35mm, more preferably 3 to 30mm, most preferably 5 to 25mm, and in this case, the handling property and productivity are excellent, and therefore, it is preferable. In particular, in the case where the cooling efficiency is improved and the productivity is remarkably improved in order to reduce the thermal conductivity of the sheet-like dry rubber to 0.15 to 0.35W/mK, the thickness of the sheet-like dry rubber is usually in the range of 1 to 30mm, preferably 2 to 25mm, more preferably 3 to 15mm, and most preferably 4 to 12 mm.

The width of the sheet-like dry rubber extruded from the screw type biaxial extrusion dryer may be appropriately selected depending on the purpose of use, and is usually in the range of 300 to 1200mm, preferably 400 to 1000mm, more preferably 500 to 800 mm.

The temperature of the dried rubber extruded from the screw type biaxial extrusion dryer is not particularly limited, but is usually in the range of 100 to 200 ℃, preferably 110 to 180 ℃, more preferably 120 to 160 ℃.

The water content of the sheet-like dry rubber extruded from the screw type biaxial extrusion dryer is not particularly limited, but is usually less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less.

The sheet-like dry rubber extruded from the screw type biaxial extrusion dryer is not particularly limited, but is usually 1500 to 6000[ Pa.s ], preferably 2000 to 5000[ Pa.s ], more preferably 2500 to 4000[ Pa.s ], and most preferably 2500 to 3500[ Pa.s ] at a complex viscosity ([ eta ]100 ℃) at 100℃and, in this case, the extrudability and shape retention as a sheet are highly balanced, and therefore, it is preferable. That is, when the amount is not less than the lower limit, the extrudability can be further improved, and when the amount is not more than the upper limit, the deformation and fracture of the sheet-like dry rubber can be suppressed.

The sheet-like dry rubber extruded from the screw type biaxial extrusion dryer can be directly folded for use, and can be generally cut for use.

The sheet-like dry rubber is not particularly limited, and since the acrylic rubber of the present invention has strong adhesiveness, it is preferable to cut the sheet-like dry rubber after cooling the sheet-like dry rubber in order to cut the sheet-like dry rubber continuously without mixing air.

The cutting temperature of the sheet-like dry rubber is not particularly limited, but is usually 60℃or lower, preferably 55℃or lower, more preferably 50℃or lower, and in this case, the cutting property and productivity are highly balanced, so that it is preferable.

The sheet-like dry rubber is not particularly limited, and is preferably cut continuously without air, because it has a complex viscosity ([ eta ]60 ℃) of usually 15000 or less, preferably 2000 to 10000[ Pa.s ], more preferably 2500 to 7000[ Pa.s ], and most preferably 2700 to 5500[ Pa.s ].

The ratio of the complex viscosity at 100 ℃ ([ eta ]100 ℃) to the complex viscosity at 60 ℃ ([ eta ]60 ℃) ([ eta ]100 ℃/[ eta ]60 ℃) is not particularly limited, and is appropriately selected according to the purpose of use, but is usually 0.5 or more, preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, most preferably 0.85 or more, and the upper limit is usually 0.98 or less, preferably 0.97 or less, more preferably 0.96 or less, particularly preferably 0.95 or less, most preferably 0.93 or less, and in this case, air mixing can be reduced and the cutting and productivity are highly balanced, so that it is preferable.

The cooling method of the sheet-like dry rubber is not particularly limited, and the sheet-like dry rubber may be left at room temperature, and since the thermal conductivity of the sheet-like dry rubber is extremely small, the sheet-like dry rubber is preferably 0.15 to 0.35W/mK, and in order to improve productivity, forced cooling by an air cooling system under a blower or a cool air, a sprinkling system by spraying water, a dipping system by immersing in water, or the like is preferable, and an air cooling system under a blower or a cool air is particularly preferable.

In the air cooling system of the sheet-like dry rubber, for example, the sheet-like dry rubber can be extruded from a screw extruder onto a conveyor such as a conveyor belt, and conveyed and cooled while blowing cold air. The temperature of the cold air is not particularly limited, but is usually in the range of 0 to 25 ℃, preferably 5 to 25 ℃, more preferably 10 to 20 ℃. The length of cooling is not particularly limited, but is usually in the range of 5 to 500m, preferably 10 to 200m, more preferably 20 to 100 m.

The cooling rate of the sheet-like dry rubber is not particularly limited, but is usually 40℃per hour or more, preferably 50℃per hour or more, more preferably 100℃per hour or more, and particularly preferably 150℃per hour or more, and in this case, the sheet-like dry rubber is easy to cut, and air is not mixed into the molded article, so that the storage stability is good, and therefore, the sheet-like dry rubber is preferable. In the present invention, the cooling rate of the sheet-like dry rubber is usually 40℃per hour or more, preferably 50℃per hour or more, more preferably 100℃per hour or more, and particularly preferably 150℃per hour or more, and in this case, the scorch stability of the rubber composition is extremely excellent, and thus it is preferable.

The cutting length of the sheet-like dry rubber is not particularly limited and may be appropriately selected depending on the purpose of use, and is usually in the range of 100 to 800mm, preferably 200 to 500mm, more preferably 250 to 450 mm.

The acrylic rubber sheet thus obtained is excellent in handling properties, roll processability, strength properties and compression set resistance, and also is excellent in storage stability, banbury processability, crosslinkability and water resistance, and can be used as it is or in a laminated package, as compared with a pellet-shaped acrylic rubber.

< acrylic rubber bag >

The acrylic rubber bag of the present invention is formed by laminating the acrylic rubber sheets.

The ionic reactive group content, the characteristic value of the acrylic rubber constituting the present invention, the ash content, the ash component content (the total amount of sodium, magnesium, calcium, phosphorus and sulfur, the total amount of magnesium and phosphorus, the magnesium amount, or the phosphorus amount), the ash component ratio, the complex viscosity at 60 ℃ ([ eta ]60 ℃), the complex viscosity at 100 ℃ ([ eta ]100 ℃), the ratio of the complex viscosity at 100 ℃ ([ eta ]100 ℃) to the complex viscosity at 60 ℃ ([ eta ]60 ℃), the gel amount, the water content, the pH and the Mooney viscosity (ML1+4, 100 ℃) are the same as those of the above-mentioned examples and preferred ranges of the acrylic rubber sheet.

The gel amount in the acrylic rubber bag of the present invention is not particularly limited, and the value at the time of sampling at any place and measuring the deviation is arbitrarily carried out. The "method of arbitrarily sampling the gel amount at a plurality of places and measuring the gel amount" herein refers to a method of arbitrarily sampling 20 places from a large gel pack, for example, and measuring the deviation of the gel amount. The method of the present invention (melt-kneading) has a special effect, and when not melt-kneaded, the amount of gel in the rubber bag may deviate, and may not fall within this range. In the present invention, the values of 20 are all within the range of (average value.+ -. 5) wt%, preferably 20 are all within the range of (average value.+ -. 3) wt%, and in this case, the respective physical properties of the rubber mixture and the rubber crosslinked product are stable without any variation in processability, and therefore, are preferable. Further, when the gel amount at 20 is arbitrarily measured for the acrylic rubber bag, that the value at 20 is within the range of ±5 of the average value means that the gel amount at 20 is within the range of (average value-5) to (average value +5) wt%, for example, when the average value of the measured gel amounts is 20 wt%, the measured value at 20 is within the range of 15 to 25 wt%.

The specific gravity of the acrylic rubber bag of the present invention is not particularly limited, and may be appropriately selected depending on the purpose of use, but is usually 0.7 or more, preferably 0.8 or more, more preferably 0.9 or more, particularly preferably 0.95 or more, and most preferably 1 or more, and in this case, the acrylic rubber bag contains little air therein, and is excellent in storage stability, and therefore is preferred. The specific gravity of the acrylic sheet of the present invention is usually in the range of 0.7 to 1.6, preferably 0.8 to 1.5, more preferably 0.9 to 1.4, particularly preferably 0.95 to 1.3, and most preferably 1.0 to 1.2, and in this case, productivity, storage stability, crosslinking property stability of the crosslinked product, and the like are highly balanced, and thus are preferable.

The size of the acrylic rubber bag of the present invention is not particularly limited, and may be appropriately selected according to the purpose of use, and the appropriate size is: the width is usually in the range of 100 to 800mm, preferably 200 to 500mm, more preferably 250 to 450mm, the length is usually in the range of 300 to 1200mm, preferably 400 to 1000mm, more preferably 500 to 800mm, and the height (thickness) is usually in the range of 50 to 500mm, preferably 100 to 300mm, more preferably 150 to 250 mm. The shape of the acrylic rubber bag of the present invention is not limited, and may be appropriately selected depending on the purpose of use of the acrylic rubber bag, and in most cases, a rectangular parallelepiped is preferable.

The method for producing the acrylic rubber bag of the present invention is not particularly limited, and it is preferable to laminate the acrylic rubber sheets to obtain an acrylic rubber bag having less air mixing and excellent storage stability.

The lamination temperature of the acrylic rubber sheet is not particularly limited, but is usually 30 ℃ or higher, preferably 35 ℃ or higher, more preferably 40 ℃ or higher, and in this case, air mixed during lamination can be released, which is preferable. The number of lamination layers may be appropriately selected according to the size or weight of the acrylic rubber bag. The acrylic rubber bag of the present invention is integrated by the self weight of the laminated acrylic sheets.

The acrylic rubber bag of the present invention thus obtained is excellent in handling properties, roll processability, strength properties and compression set properties, and also excellent in storage stability, banbury processability, crosslinking properties and water resistance, as compared with the pellet acrylic rubber, and can be used as it is or cut into a desired amount and put into a mixer such as a banbury, roll or the like.

< rubber mixture >

The rubber mixture of the present invention is characterized by comprising the acrylic rubber sheet and/or the acrylic rubber bag, a filler, and a crosslinking agent.

The filler to be contained in the rubber mixture is not particularly limited, and examples thereof include reinforcing fillers and non-reinforcing fillers, and reinforcing fillers are preferable, and in this case, the rubber mixture is excellent in roll processability, banbury processability and short-time crosslinkability, and the crosslinked product is extremely excellent in water resistance, strength characteristics and compression set resistance, and therefore is preferable.

Examples of the reinforcing filler include carbon blacks such as furnace black, acetylene black, thermal black, channel black and graphite; and silica such as wet silica, dry silica and colloidal silica. Examples of the non-reinforcing filler include quartz powder, diatomaceous earth, zinc white, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, calcium sulfate, and barium sulfate.

These fillers may be used alone or in combination of 2 or more kinds, and the amount thereof may be appropriately selected within a range not to impair the effects of the present invention, and is usually in a range of 1 to 200 parts by weight, preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight, relative to 100 parts by weight of the acrylic rubber sheet and/or acrylic rubber bag of the present invention.

The crosslinking agent used in the rubber mixture is not particularly limited, and conventionally known crosslinking agents may be selected according to the purpose of use, and examples thereof include inorganic crosslinking agents such as sulfur compounds, organic crosslinking agents, and the like, and organic crosslinking agents are preferable. The crosslinking agent may be a polyvalent compound or a monovalent compound, and preferably a polyvalent compound having 2 or more reactive groups. Further, the crosslinking agent may be either an ion-crosslinkable compound or a radical-crosslinkable compound, and is preferably an ion-crosslinkable compound.

The organic crosslinking agent is not particularly limited, but is preferably an ion-crosslinkable organic compound, and particularly preferably a polyion organic compound. When the crosslinking agent is a polyion organic compound (polyion crosslinkable compound), the rubber mixture is particularly preferable because it is excellent in roll processability, banbury processability and crosslinking property in a short time, and the crosslinked product is extremely excellent in water resistance, strength characteristics and compression set resistance. The "ion" of the ion-crosslinkable or multi-component ion is an ion-reactive ion, and is not particularly limited as long as it is an ion-reactive group of the ion-reactive group-containing monomer of the above-mentioned acrylic rubber, and examples thereof include ion-crosslinkable organic compounds having an ion-reactive group such as an amine group, an epoxy group, a carboxyl group, and a thiol group.

Specific examples of the polyionic organic compound include a polyamine compound, a polyepoxide compound, a polycarboxylic acid compound, a polythiol compound, and the like, and a polyamine compound and a polythiol compound are preferable, and a polyamine compound is more preferable.

Examples of the polyamine compound include: aliphatic polyamine compounds such as hexamethylenediamine, hexamethylenediamine carbamate, and N, N' -biscinnamal-1, 6-hexamethylenediamine; 4,4 '-methylenedianiline, p-phenylenediamine, m-phenylenediamine, 4' -diaminodiphenyl ether, 3,4 '-diaminodiphenyl ether, 4' - (m-phenylenediisopropylidene) diphenylamine, 4'- (p-phenylenediisopropylidene) diphenylamine, and aromatic polyamine compounds such as 2,2' -bis [4- (4-aminophenoxy) phenyl ] propane, 4 '-diaminobenzanilide, 4' -bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, and 1,3, 5-benzenetriamine. Among them, hexamethylenediamine carbamate, 2' -bis [4- (4-aminophenoxy) phenyl ] propane and the like are preferable. Further, as the polyamine compound, carbonates thereof are preferably used. These polyamine compounds are particularly preferably used in combination with a carboxyl group-containing acrylic rubber sheet or acrylic rubber bag, or an epoxy group-containing acrylic rubber sheet or acrylic rubber bag.

As the polythiol compounds, preferably using triazine thiol compounds, can be cited for example, 6-three mercapto-s three triazine, 2-two thiol-s three triazine, 1-two butyl amino 3, 5-two mercapto three triazine, 2-two butyl amino 4, 6-two thiol-s three triazine, 1-phenyl amino 3, 5-two mercapto three triazine, 2,4, 6-three mercapto-1, 3,5 three triazine, 1-hexyl amino 3, 5-two mercapto three triazine. These triazine thiol compounds are particularly preferably used in combination with an acrylic rubber sheet or acrylic rubber bag containing chlorine atoms.

Examples of the other polyvalent organic compound include a polyvalent carboxylic acid compound such as tetradecanedioic acid, a metal dithiocarbamate such as zinc dimethyldithiocarbamate, and the like. These other polyvalent organic compounds are particularly preferably used in combination with an epoxy group-containing acrylic rubber sheet or acrylic rubber bag.

These crosslinking agents may be used alone or in combination of 2 or more, and the amount thereof is usually 0.001 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, relative to 100 parts by weight of the acrylic rubber sheet and/or the acrylic rubber bag of the present invention. When the amount of the crosslinking agent is within this range, rubber elasticity can be sufficiently obtained, and mechanical strength as a crosslinked rubber product can be made excellent.

The rubber mixture of the present invention may be added with an antioxidant as needed. The type of the antioxidant is not particularly limited, and examples thereof include: other phenol-based antioxidants such as 2, 6-di-tert-butyl-4-methylphenol, 2, 6-di-tert-butylphenol, butylhydroxyanisole, 2, 6-di-tert-butyl- α -dimethylamino-p-cresol, octadecyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, styrenated phenol, 2' -methylenebis (6- α -methylbenzyl-p-cresol), 4' -methylenebis (2, 6-di-tert-butylphenol), 2' -methylenebis (4-methyl-6-tert-butylphenol), 2, 4-bis [ (octylthio) methyl ] -6-methylphenol, 2' -thiobis- (4-methyl-6-tert-butylphenol), 4' -thiobis (6-tert-butyl-o-cresol), 2, 6-di-tert-butyl-4- [4, 6-bis (octylthio) -1,3, 5-triazin-2-ylamino ] phenol; phosphite antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyl dipropylene glycol and bisphosphite; thioester-based antioxidants such as dilauryl thiodipropionate; amine-based antioxidants such as phenyl- α -naphthylamine, phenyl- β -naphthylamine, p- (p-toluenesulfonamide) -diphenylamine, 4'- (α, α -dimethylbenzyl) diphenylamine, N-diphenyl-p-phenylenediamine, N-isopropyl-N' -phenyl-p-phenylenediamine, butyraldehyde-aniline polycondensate; imidazole-based antioxidants such as 2-mercaptobenzimidazole; quinoline antioxidants such as 6-ethoxy-2, 4-trimethyl-1, 2-dihydroquinoline; hydroquinone-based antioxidants such as 2, 5-di (t-amyl) hydroquinone. Among them, amine-based antioxidants are particularly preferable.

These antioxidants may be used alone or in combination of 2 or more kinds, and the amount thereof is in the range of 0.01 to 15 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, relative to 100 parts by weight of the acrylic rubber sheet and/or the acrylic rubber bag of the present invention.

The acrylic rubber sheet or the acrylic rubber bag of the present invention may be used alone as the rubber component which is the main component of the rubber mixture of the present invention, or may be used in combination with other rubber components as required.

The other rubber component to be combined with the acrylic rubber sheet or the acrylic rubber bag of the present invention is not particularly limited, and examples thereof include natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicone rubber, fluororubber, olefin elastomer, styrene elastomer, vinyl chloride elastomer, polyester elastomer, polyamide elastomer, polyurethane elastomer, polysiloxane elastomer, and the like.

These other rubber components can be used alone or in combination of 2 or more. The shape of these other rubber components may be any of a pellet, a strand, a bale, a sheet, a powder, and the like. The amount of the other rubber component to be used may be appropriately selected within a range not to impair the effect of the present invention, and is, for example, usually 70 parts by weight or less, preferably 50 parts by weight or less, more preferably 30 parts by weight or less, particularly preferably 20 parts by weight or less, and most preferably 10 parts by weight or less, relative to 100 parts by weight of the acrylic rubber sheet and/or acrylic rubber bag of the present invention.

The rubber mixture of the present invention contains the above-described acrylic rubber sheet of the present invention and/or the acrylic rubber bag of the present invention, filler and crosslinking agent as essential components, and further contains an antioxidant and other rubber components as required, and further, other additives commonly used in the art, such as a crosslinking aid, a crosslinking accelerator, a crosslinking retarder, a silane coupling agent, a plasticizer, a processing aid, a lubricant, a pigment, a colorant, an antistatic agent, a foaming agent, and the like, can be optionally blended as required. These other compounding agents may be used alone or in combination of 2 or more kinds, and the compounding amount thereof may be appropriately selected within a range that does not impair the effects of the present invention.

The method for producing the rubber mixture of the present invention includes a method of mixing the acrylic rubber sheet and/or the acrylic rubber bag of the present invention, the filler, the crosslinking agent, and optionally, the antioxidant, other rubber components, and other compounding agents, and any means used in the conventional rubber processing field can be used at the time of mixing, for example, an open roll mill, a Banbury mixer, various kneaders, and the like. The mixing order of the respective components may be a usual order in the rubber processing field, and for example, it is preferable that after the components which are not easily reacted or decomposed by heat are sufficiently mixed, a crosslinking agent or the like which is a component which is easily reacted or decomposed by heating is mixed for a short period of time at a temperature at which the reaction or decomposition does not occur.

< crosslinked rubber >

The rubber crosslinked product of the present invention is obtained by crosslinking the rubber mixture.

The rubber crosslinked product of the present invention can be produced as follows: the rubber mixture of the present invention is molded by a molding machine such as an extruder, an injection molding machine, a compressor, a roll, or the like, which corresponds to a desired shape, and is subjected to a crosslinking reaction by heating, whereby the shape is cured as a rubber crosslinked product to produce a rubber crosslinked product. In this case, the crosslinking may be performed after the preforming, or may be performed at the same time as the shaping. The molding temperature is usually 10 to 200℃and preferably 25 to 150 ℃. The crosslinking temperature is usually 100 to 250 ℃, preferably 130 to 220 ℃, more preferably 150 to 200 ℃, and the crosslinking time is usually 0.1 minutes to 10 hours, preferably 1 minute to 5 hours. As the heating method, a method for crosslinking the rubber, such as pressing heating, steam heating, oven heating, and hot air heating, can be appropriately selected.

The rubber crosslinked product of the present invention may be subjected to secondary crosslinking by further heating according to the shape, size, etc. of the rubber crosslinked product. The secondary crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., and is preferably carried out for 1 to 48 hours. The heating method and the heating temperature are properly selected.

The rubber crosslinked product of the present invention maintains tensile strength, elongation, hardness, etc. as basic properties of rubber, and has excellent compression set resistance and water resistance.

The rubber crosslinked material of the present invention can be preferably used as, for example, by effectively utilizing the above characteristics: sealing materials such as O-rings, sealing materials, diaphragms, oil seals, shaft seals, bearing seals, mechanical seals, wellhead seals, and electrical/electronic equipment seals; a rocker cover gasket mounted on a joint portion between a cylinder block and a cylinder head, an oil pan gasket mounted on a joint portion between an oil pan and a cylinder head or a transmission case, a gasket for a fuel cell spacer mounted between a stack of cases sandwiching a unit cell having a positive electrode, an electrolyte plate and a negative electrode, a gasket for a top cover of a hard disk drive, and the like; a buffer material and a vibration-proof material; a wire coating material; industrial belts; tubes/hoses; sheets, and the like.

The rubber crosslinked product of the present invention can be used also as an extrusion molded article and a die crosslinked article for use in automobiles, and can be preferably used as, for example: various hoses such as fuel hose, filler neck hose, vent hose, paper hose, fuel oil hose around the fuel tank such as oil hose, air hose such as turbine air hose, transmission control hose, radiator hose, heater hose, brake hose, and air conditioning hose.

< Structure of apparatus for manufacturing acrylic rubber sheet >

Next, an apparatus structure for manufacturing an acrylic rubber sheet and an acrylic rubber bag according to an embodiment of the present invention will be described. Fig. 1 is a diagram schematically showing an example of an acrylic rubber manufacturing system having an apparatus structure for manufacturing an acrylic rubber sheet and an acrylic rubber bag according to an embodiment of the present invention. In the production of the acrylic rubber sheet and the acrylic rubber bag of the present invention, for example, the acrylic rubber production system 1 shown in fig. 1 can be used.

The acrylic rubber production system 1 shown in fig. 1 is composed of an emulsion polymerization reactor, a coagulation device 3, a cleaning device 4, a water remover 43, and a screw type biaxial extrusion dryer, which are not shown.

The emulsion polymerization reactor is configured to perform the above-described treatment in the emulsion polymerization step. Not shown in fig. 1, the emulsion polymerization reactor includes, for example, a polymerization reaction tank, a temperature control unit for controlling a reaction temperature, and a stirring device having a motor and stirring blades. In the emulsion polymerization reactor, water and an emulsifier are mixed with a monomer component for forming an acrylic rubber, and emulsification is performed while properly stirring with a stirrer, and an emulsion polymerization reaction is initiated in the presence of a redox catalyst containing an inorganic radical generator and a reducing agent, and a chain transfer agent is added after batchwise during the polymerization to obtain an emulsion polymerization solution. The emulsion polymerization reactor may be any of a batch type, a semi-batch type, and a continuous type, and may be any of a tank type reactor and a tube type reactor.

The coagulation apparatus 3 shown in fig. 1 is configured to perform the above-described treatment in the coagulation step. As schematically illustrated in fig. 1, the solidification apparatus 3 includes, for example, a stirring tank 30, a heating unit 31 for heating the inside of the stirring tank 30, a temperature control unit, not shown, for controlling the temperature in the stirring tank 30, a stirring device 34 including a motor 32 and stirring blades 33, and a drive control unit, not shown, for controlling the rotational speed and rotational speed of the stirring blades 33. In the coagulation apparatus 3, the emulsion polymerization liquid obtained in the emulsion polymerization reaction is brought into contact with the coagulation liquid to coagulate the emulsion polymerization liquid, whereby aqueous pellets can be produced.

In the coagulation device 3, for example, the emulsion polymerization liquid is brought into contact with the coagulation liquid by adding the emulsion polymerization liquid to the stirred coagulation liquid. That is, the stirring tank 30 of the coagulation device 3 is filled with a coagulation liquid in advance, and an emulsion polymerization liquid is added to the coagulation liquid and brought into contact therewith to coagulate the emulsion polymerization liquid, thereby producing an aqueous pellet.

The heating unit 31 of the solidifying apparatus 3 is configured to heat the solidifying liquid filled in the stirring tank 30. The temperature control unit of the solidifying apparatus 3 is configured to control the temperature in the stirring tank 30 by controlling the heating operation of the heating unit 31 while monitoring the temperature in the stirring tank 30 measured by the thermometer. The temperature of the solidification liquid in the stirring tank 30 is controlled to be generally 40 ℃ or higher, preferably 40 to 90 ℃, and more preferably 50 to 80 ℃ by the temperature control unit.

The stirring device 34 of the solidifying apparatus 3 is configured to stir the solidification liquid filled into the stirring tank 30. Specifically, the stirring device 34 has a motor 32 that generates rotational power, and stirring blades 33 that are deployed in a direction perpendicular to the rotational axis of the motor 32. The stirring blade 33 can rotate around a rotation axis by the rotation power of the motor 32 in the solidification liquid filled in the stirring tank 30, thereby allowing the solidification liquid to flow. The shape, size, number of the stirring vanes 33, and the like are not particularly limited.

The drive control unit of the coagulation device 3 is configured to control the rotational drive of the motor 32 of the stirring device 34, and set the rotational speed and the rotational speed of the stirring blade 33 of the stirring device 34 to predetermined values. The stirring number of the coagulation liquid is, for example, usually 100rpm or more, preferably 200 to 1000rpm, more preferably 300 to 900rpm, and particularly preferably 400 to 800rpm by controlling the rotation of the stirring blade 33 by the drive control unit. The rotation of the stirring blade 33 is controlled by the drive control unit so that the peripheral speed of the solidification liquid is usually 0.5m/s or more, preferably 1m/s or more, more preferably 1.5m/s or more, particularly preferably 2m/s or more, and most preferably 2.5m/s or more. Further, the rotation of the stirring blade 33 is controlled by the drive control unit so that the upper limit value of the peripheral speed of the solidification liquid is usually 50m/s or less, preferably 30m/s or less, more preferably 25m/s or less, and most preferably 20m/s or less.

The cleaning apparatus 4 shown in fig. 1 is configured to perform the above-described cleaning process. As schematically illustrated in fig. 1, the cleaning apparatus 4 includes, for example, a cleaning tank 40, a heating unit 41 that heats the interior of the cleaning tank 40, and a temperature control unit, not illustrated, that controls the temperature in the cleaning tank 40. In the cleaning device 4, the aqueous aggregate generated in the coagulation device 3 is mixed with a large amount of water and cleaned, so that the ash content in the finally obtained acrylic rubber sheet or acrylic rubber bag can be effectively reduced.

The heating unit 41 of the cleaning apparatus 4 is configured to heat the inside of the cleaning tank 40. The temperature control unit of the cleaning apparatus 4 is configured to control the temperature in the cleaning tank 40 by controlling the heating operation of the heating unit 41 while monitoring the temperature in the cleaning tank 40 measured by the thermometer. As described above, the temperature of the washing water in the washing tub 40 is usually controlled to 40 ℃ or higher, preferably 40 to 100 ℃, more preferably 50 to 90 ℃, and most preferably 60 to 80 ℃.

The aqueous pellets washed by the washing apparatus 4 are supplied to a screw type biaxial extrusion dryer 5 for performing a dehydration step and a drying step. At this time, the washed aqueous pellets are preferably supplied to the screw type biaxial extrusion dryer 5 through a water remover 43 capable of separating free water. As the water removing machine 43, for example, a metal mesh, a screen, an electric screen, or the like can be used.

When the washed aqueous pellets are fed to the screw type biaxial extrusion dryer 5, the temperature of the aqueous pellets is preferably 40 ℃ or higher, more preferably 60 ℃ or higher. For example, by setting the temperature of the water used for washing in the washing device 4 to 60 ℃ or higher (for example, 70 ℃), the temperature of the aqueous pellets when supplied to the screw type biaxial extrusion dryer 5 can be maintained to 60 ℃ or higher, or the temperature of the aqueous pellets can be heated to 40 ℃ or higher, preferably 60 ℃ or higher when transferred from the washing device 4 to the screw type biaxial extrusion dryer 5. This can effectively perform the dehydration step and the drying step as subsequent steps, and can greatly reduce the water content of the finally obtained dried rubber.

The screw type biaxial extrusion dryer 5 shown in fig. 1 is configured to perform the above-described dehydration step and drying step. Fig. 1 shows a screw type biaxial extrusion dryer 5 as a preferable example, and a centrifuge, a squeezer, or the like may be used as a dehydrator for performing the dehydration step, and a hot air dryer, a decompression dryer, an expansion dryer, a kneading dryer, or the like may be used as a dryer for performing the drying step.

The screw type biaxial extrusion dryer 5 is configured to mold the dried rubber obtained through the dehydration step and the drying step into a predetermined shape and discharge the molded rubber. Specifically, the screw type biaxial extrusion dryer 5 is constituted as: the apparatus comprises a dewatering cylinder 53 and a dryer cylinder 54, and further comprises a die 59 on the downstream side of the screw type twin screw extrusion dryer 5, wherein the dewatering cylinder 53 has a function as a dewatering machine for dewatering the aqueous pellets washed by the washing apparatus 4, the dryer cylinder 54 has a function as a dryer for drying the aqueous pellets, and the die 59 has a molding function for molding the aqueous pellets.

The structure of the screw type biaxial extrusion dryer 5 will be described below with reference to fig. 2. Fig. 2 is a diagram showing a structure as a preferable specific example of the screw type biaxial extrusion dryer 5 shown in fig. 1. The above-described dehydration and drying process can be favorably performed by the screw type biaxial extrusion dryer 5.

The screw type biaxial extrusion dryer 5 shown in fig. 2 is a biaxial screw type extrusion dryer having a pair of screws, not shown, in a barrel unit 51. The screw type biaxial extrusion dryer 5 has a drive unit 50 that rotationally drives a pair of screws in a barrel unit 51. With such a structure, the acrylic rubber can be dried by applying high shear, which is preferable. The driving unit 50 is installed at the upstream end (left end in fig. 2) of the barrel unit 51. Further, the screw type biaxial extrusion dryer 5 has a die 59 at the downstream end (right end in fig. 2) of the barrel unit 51.

The barrel unit 51 has a supply barrel portion 52, a dehydration barrel portion 53, and a dryer barrel portion 54 from the upstream side to the downstream side (from the left side to the right side in fig. 2).

The supply cylinder portion 52 is constituted by two supply cylinders, i.e., a first supply cylinder 52a and a second supply cylinder 52 b.

Further, the dehydration cylinder section 53 is constituted by three dehydration cylinders, namely, a first dehydration cylinder 53a, a second dehydration cylinder 53b, and a third dehydration cylinder 53 c.

The dryer section 54 is composed of eight dryer cylinders, i.e., a first dryer cylinder 54a, a second dryer cylinder 54b, a third dryer cylinder 54c, a fourth dryer cylinder 54d, a fifth dryer cylinder 54e, a sixth dryer cylinder 54f, a seventh dryer cylinder 54g, and an eighth dryer cylinder 54 h.

The barrel unit 51 is configured to connect 13 separate barrels 52a to 52b, 53a to 53c, 54a to 54h from the upstream side to the downstream side.

The screw type biaxial extrusion dryer 5 heats the respective cylinders 52a to 52b, 53a to 53c, 54a to 54h, and has heating means, not shown, for heating the aqueous pellets in the respective cylinders 52a to 52b, 53a to 53c, 54a to 54h to a predetermined temperature. The heating units have numbers corresponding to the respective barrels 52a to 52b, 53a to 53c, 54a to 54 h. As such heating means, for example, a structure may be employed in which high-temperature steam or the like is supplied from the steam supply means to the steam flow jackets formed in the respective cylinders 52a to 52b, 53a to 53c, 54a to 54h, but the invention is not limited thereto. The screw type biaxial extrusion dryer 5 further includes a temperature control unit, not shown, for controlling the set temperatures of the heating units corresponding to the respective cylinders 52a to 52b, 53a to 53c, and 54a to 54 h.

The number of supply cylinders, dewatering cylinders, and drying cylinders constituting the

respective cylinder sections

52, 53, 54 in the cylinder unit 51 is not limited to the form shown in fig. 2, and may be set to the number corresponding to the water content of the aqueous pellets of the acrylic rubber to be dried.

For example, the number of supply cylinders to be provided in the cylinder portion 52 is 1 to 3, for example. The number of the dehydrators of the dehydrator cylinder 53 is preferably 2 to 10, for example, and if it is 3 to 6, it is more preferable that the dehydration of the water-containing pellets of the adhesive acrylic rubber can be performed more efficiently. The number of the dryer cylinders of the dryer cylinder section 54 is preferably 2 to 10, more preferably 3 to 8, for example.

The pair of screws in the barrel unit 51 are rotationally driven by a driving unit such as a motor housed in the driving unit 50. The pair of screws extend from the upstream side to the downstream side in the barrel unit 51, and are driven by rotation to mix the aqueous pellets supplied to the supply barrel unit 52 and convey the mixed pellets to the downstream side. The pair of screws are preferably biaxial meshing type in which the screw ridge portion and the screw groove portion are in meshing engagement with each other, whereby the dewatering efficiency and drying efficiency of the aqueous pellet can be improved.

The rotation directions of the pair of screws may be the same or different, and from the viewpoint of self-cleaning performance, the pair of screws are preferably rotated in the same direction. The screw shape of the pair of screws is not particularly limited as long as it is a shape required in each of the

cylinder portions

52, 53, 54.

The supply barrel section 52 is a region in which aqueous pellets are supplied into the barrel unit 51. The first supply barrel 52a of the supply barrel section 52 has a feed port 55 for supplying aqueous pellets into the barrel unit 51.

The dewatering cylinder 53 is a region for separating and discharging a liquid (slurry) containing a coagulant or the like from the aqueous pellet.

The first to third dewatering cylinders 53a to 53c constituting the dewatering cylinder 53 have

dewatering slits

56a, 56b, 56c for discharging the water of the aqueous pellets to the outside, respectively. A plurality of

dewatering slits

56a, 56b, 56c are formed in each dewatering cylinder 53a to 53 c.

The slit width, that is, the mesh width of each

dewatering slit

56a, 56b, 56c is appropriately selected depending on the conditions of use, and is usually set to 0.01 to 5mm, preferably 0.1 to 1mm, more preferably 0.2 to 0.6mm, from the viewpoint that the loss of the aqueous pellets is small and the aqueous pellets can be efficiently dewatered.

The removal of water from the aqueous pellets in each of the dewatering cylinders 53a to 53c of the dewatering cylinder 53 is performed in both a liquid state and a vapor state from the

dewatering slits

56a, 56b, 56 c. The dewatering cylinder 53 of the present embodiment is defined as a dewatering cylinder in which water is removed in a liquid state, and a dewatering cylinder in which water is removed in a vapor state is defined as a dewatering cylinder.

The dehydration cylinder 53 is preferable because the water content of the adhesive acrylic rubber can be reduced efficiently by combining drainage and steam discharge. In the dewatering cylinder section 53, which of the first to third dewatering cylinders 53a to 53c is used for draining or discharging steam can be set appropriately according to the purpose of use, and in general, the dewatering cylinder used for draining can be increased when the ash content in the produced acrylic rubber is reduced. In this case, for example, as shown in fig. 2, water is discharged in the first and

second dewatering cylinders

53a, 53b on the upstream side, and steam is discharged in the third dewatering cylinder 53c on the downstream side. For example, in the case where the dewatering cylinder 53 has four dewatering cylinders, it is conceivable to drain water in three dewatering cylinders on the upstream side and drain steam in one dewatering cylinder on the downstream side. On the other hand, in the case of decreasing the water content, the dehydration cylinder in which the steam discharge is performed may be increased.

As described in the above-described dehydration and drying steps, the setting temperature of the dehydration barrel portion 53 is usually 60 to 150 ℃, preferably 70 to 140 ℃, more preferably 80 to 130 ℃, the setting temperature of the dehydration barrel for dehydrating in a water discharge state is usually 60 to 120 ℃, preferably 70 to 110 ℃, more preferably 80 to 100 ℃, and the setting temperature of the dehydration barrel for dehydrating in a steam discharge state is usually 100 to 150 ℃, preferably 105 to 140 ℃, more preferably 110 to 130 ℃.

The dryer section 54 is a region in which dehydrated aqueous pellets are dried under reduced pressure. The second, fourth, sixth and eighth dryer barrels 54b, 54d, 54f, 54h constituting the dryer barrel section 54 have

exhaust ports

58a, 58b, 58c, 58d for exhaust, respectively. Exhaust pipes, not shown, are connected to the

exhaust ports

58a, 58b, 58c, 58d, respectively.

A vacuum pump, not shown, is connected to each end of each exhaust pipe, and the interior of the dryer cylinder 54 can be depressurized to a predetermined pressure by the operation of these vacuum pumps. The screw extruder 5 has a pressure control unit, not shown, for controlling the operation of these vacuum pumps and controlling the degree of pressure reduction in the dryer barrel 54.

The degree of decompression in the dryer barrel 54 can be appropriately selected, and is set to be generally 1 to 50kPa, preferably 2 to 30kPa, and more preferably 3 to 20kPa, as described above.

The set temperature in the dryer barrel 54 may be appropriately selected, and is usually set to 100 to 250 ℃, preferably 110 to 200 ℃, and more preferably 120 to 180 ℃ as described above.

In each of the dryer cylinders 54a to 54h constituting the dryer cylinder section 54, the set temperatures in all of the dryer cylinders 54a to 54h may be set to similar values or may be different values, and if the temperature on the downstream side (die 59 side) is set to a higher temperature than the temperature on the upstream side (dryer cylinder section 53 side), the operation efficiency is improved, which is preferable.

The die 59 is a die disposed at the downstream end of the barrel unit 51, and has a discharge port having a predetermined nozzle shape. The acrylic rubber dried in the dryer cylinder 54 is extruded through the outlet of the die 59 to a shape corresponding to a predetermined nozzle shape. The acrylic rubber passing through the die 59 can be molded into various shapes such as a pellet, a column, a round bar, and a sheet according to the nozzle shape of the die 59, and in the present invention, can be molded into a sheet. A perforated plate, a metal mesh, or the like may be provided between the screw and the die 59.

The aqueous pellets of the acrylic rubber obtained through the cleaning step are supplied from the feed port 55 to the supply cylinder portion 52. The aqueous pellets supplied to the supply cylinder section 52 are sent from the supply cylinder section 52 to the dehydration cylinder section 53 by rotation of a pair of screws in the cylinder unit 51. In the dewatering cylinder 53, as described above, the

dewatering slits

56a, 56b, and 56c provided in the first to third dewatering cylinders 53a to 53c respectively drain water and steam contained in the aqueous pellets, and dewater the aqueous pellets.

The aqueous pellets dehydrated by the dehydrator cylinder 53 are sent to the dryer cylinder 54 by rotation of a pair of screws in the cylinder unit 51. The water-containing pellets sent to the dryer section 54 are plasticized and mixed to form a melt, and are sent to the downstream side while being heated by heat release. Then, the moisture contained in the melt of the acrylic rubber is vaporized, and the moisture (vapor) is discharged to the outside through an exhaust duct (not shown) connected to each of the

exhaust ports

58a, 58b, 58c, 58 d.

As described above, the aqueous pellets are dried by the dryer cylinder 54 to obtain a melt of the acrylic rubber, and the acrylic rubber is supplied to the die 59 by the rotation of the pair of screws in the cylinder unit 51, and extruded from the die 59.

Here, an example of the operating conditions of the screw type biaxial extrusion dryer 5 of the present embodiment is given.

The rotation speed (N) of the pair of screws in the barrel unit 51 may be appropriately selected depending on the respective conditions, and is usually 10 to 1000rpm, preferably 50 to 750rpm, more preferably 100 to 500rpm, and most preferably 120 to 300rpm, from the viewpoint of efficiently reducing the water content of the acrylic rubber and the amount of the methyl ethyl ketone insoluble component.

The extrusion amount (Q) of the acrylic rubber is not particularly limited, but is usually 100 to 1500 kg/hr, preferably 300 to 1200 kg/hr, more preferably 400 to 1000 kg/hr, and most preferably 500 to 800 kg/hr.

The ratio (Q/N) of the extrusion amount (Q) of the acrylic rubber to the rotation speed (N) of the screw is not particularly limited, but is usually 1 to 20, preferably 2 to 10, more preferably 3 to 8, particularly preferably 4 to 6.

The maximum torque in the barrel unit 51 is not particularly limited, but is usually in the range of 30 to 100n·m, preferably 35 to 75n·m, and more preferably 40 to 60n·m.

The specific energy consumption in the cylinder unit 51 is not particularly limited, but is usually 0.1 to 0.25[ kw.h/kg ] or more, preferably 0.13 to 0.23[ kw.h/kg ], and more preferably 0.15 to 0.2[ kw.h/kg ].

The specific power in the cylinder unit 51 is not particularly limited, but is usually 0.2 to 0.6[ A.multidot.h/kg ] or more, preferably 0.25 to 0.55[ A.multidot.h/kg ], and more preferably 0.35 to 0.5[ A.multidot.h/kg ].

The shear rate in the barrel unit 51 is not particularly limited, but is usually 40 to 150[1/s ] or more, preferably 45 to 125[1/s ], and more preferably 50 to 100[1/s ].

The shear viscosity of the acrylic rubber in the cylinder unit 51 is not particularly limited, but is usually 4000 to 8000[ Pa.s ] or less, preferably 4500 to 7500[ Pa.s ], and more preferably 5000 to 7000[ Pa.s ].

The cooling device 6 shown in fig. 1 is configured to cool the dried rubber obtained through the dehydration step by a dehydrator and the drying step by a dryer. As the cooling method by the cooling device 6, various methods including an air cooling method by blowing or cooling air, a water spraying method by spraying water, an immersion method by immersing in water, and the like can be employed. In addition, the dried rubber may be cooled by leaving it at room temperature.

As described above, the dried rubber discharged from the screw extruder 5 is extruded into various shapes such as pellets, columns, round bars, sheets, etc., according to the nozzle shape of the die 59, and is molded into a sheet in the present invention. Hereinafter, a conveyor type cooling device 60 for cooling the sheet-like rubber 10 molded into a sheet-like shape will be described as an example of the cooling device 6 with reference to fig. 3.

Fig. 3 shows a structure of a preferred conveyor type cooling device 60 as the cooling device 6 shown in fig. 1. The conveyor cooling device 60 shown in fig. 3 is configured to cool by an air cooling system while conveying the sheet-like dry rubber 10 discharged from the discharge port of the die 59 of the screw extruder 5. By using this conveyor cooling device 60, the sheet-like dry rubber discharged from the screw extruder 5 can be cooled appropriately.

The conveying cooling device 60 shown in fig. 3 is directly connected to the die 59 of the screw extruder 5 shown in fig. 2, or is disposed in the vicinity of the die 59.

The conveyor cooling device 60 has a conveyor 61 that conveys the sheet-like dry rubber 10 discharged from the die 59 of the screw extruder 5 in the direction of arrow a in fig. 3, and a cooling unit 65 that blows cold air to the sheet-like dry rubber 10 on the conveyor 61.

The conveyor 61 includes

rollers

62 and 63, and a conveyor belt 64 wound around the

rollers

62 and 63 in tension to place the sheet-like dry rubber 10 thereon. The conveyor 61 is configured to continuously convey the sheet-like dry rubber 10 discharged from the die 59 of the screw extruder 5 to the downstream side (right side in fig. 3).

The cooling unit 65 is not particularly limited, and examples thereof include those having the following structures: the cooling air sent from a cooling air generating unit, not shown, can be blown to the surface of the sheet-like dry rubber 10 on the conveyor belt 64.

The length L1 of the conveyor 61 and the cooling unit 65 of the conveyor cooling device 60 (the length of the portion capable of blowing out the cooling air) is not particularly limited, and is, for example, 10 to 100m, preferably 20 to 50m. The conveying speed of the sheet-like dry rubber 10 in the conveying type cooling device 60 can be appropriately adjusted according to the length L1 of the conveyor 61 and the cooling unit 65, the discharge speed of the sheet-like dry rubber 10 discharged from the die 59 of the screw extruder 5, the target cooling speed, the cooling time, and the like, and is, for example, 10 to 100 m/hr, and more preferably 15 to 70 m/hr.

According to the conveyor cooling device 60 shown in fig. 3, the sheet-like dry rubber 10 can be cooled by blowing cold air from the cooling unit 65 to the sheet-like dry rubber 10 while conveying the sheet-like dry rubber 10 discharged from the die 59 of the screw extruder 5 by the conveyor 61.

The transport cooling device 60 is not limited to the configuration having one conveyor 61 and one cooling unit 65 as shown in fig. 3, and may be configured to have two or more conveyors 61 and two or more cooling units 65 corresponding thereto. In this case, the total length of each of the two or more conveyors 61 and the cooling unit 65 may be within the above range.

The rubber packing device 7 shown in fig. 1 is configured to process the dried rubber extruded from the screw extruder 5 and cooled by the cooling device 6 to manufacture a one-piece rubber pack. As described above, the screw extruder 5 can extrude the dried rubber into various shapes such as pellets, columns, round bars, and sheets, and the rubber packing device 7 is configured to pack the dried rubber thus molded into various shapes. The weight, shape, etc. of the acrylic rubber bag manufactured by the rubber bag forming apparatus 7 are not particularly limited, and for example, an acrylic rubber bag having a substantially rectangular parallelepiped shape of about 20kg is manufactured.

The rubber packing device 7 has, for example, a packing machine, and can compress the cooled dry rubber by the packing machine to manufacture an acrylic rubber packing.

In the case of producing the sheet-like dry rubber by the screw extruder 5, an acrylic rubber bag in which the sheet-like dry rubber 10 is laminated may be produced. For example, in the rubber packing device 7 disposed downstream of the conveyor cooling device 60 shown in fig. 3, a cutting mechanism that cuts the sheet-like dry rubber 10 may be provided. Specifically, the cutting mechanism of the rubber packing device 7 is configured to continuously cut the cooled sheet-like dry rubber 10 at predetermined intervals, for example, and process the sheet-like dry rubber 16 into a predetermined size. By stacking a plurality of pieces of the sliced dry rubber 16 cut into a predetermined size by a cutting mechanism, a rubber-coated acrylic rubber in which the sliced dry rubber 16 is stacked can be produced.

In the case of producing a rubber-coated acrylic rubber in which the sliced dried rubber 16 is laminated, it is preferable to laminate the sliced dried rubber 16 at 40℃or higher, for example. By stacking the sliced dried rubber 16 at 40 ℃ or higher, air can be discharged satisfactorily by further cooling and compression due to its own weight.

Examples

The present invention will be described more specifically with reference to the following examples and comparative examples. Unless otherwise specifically indicated, "parts", "percent" and "ratio" in each example are by weight. Further, the physical properties were evaluated by the following methods.

[ monomer composition ]

Regarding the monomer composition in the acrylic rubber, the monomer structure of each monomer unit in the acrylic rubber was confirmed by 1H-NMR, and whether the reactivity of the reactive group remained in the acrylic rubber, and the content of each reactive group thereof were confirmed by the following method. The content ratio of each monomer unit in the acrylic rubber is calculated from the amount of each monomer used in the polymerization reaction and the polymerization conversion rate. Specifically, since the polymerization reaction is an emulsion polymerization reaction, it was not confirmed that the unreacted monomer was about 100% in terms of polymerization conversion, and therefore the content ratio of each monomer unit in the rubber was the same as the amount of each monomer used.

[ reactive group content ]

The content of the reactive group in the acrylic rubber sheet or the acrylic rubber bag was determined by the following method.

(1) The carboxyl group amount was calculated by dissolving the rubber sample in acetone and conducting potential difference titration with potassium hydroxide solution.

(2) The epoxy group amount was calculated by dissolving the rubber sample in methyl ethyl ketone, adding an equivalent amount of hydrochloric acid thereto and reacting it with the epoxy group, and titrating the residual hydrochloric acid amount with potassium hydroxide.

(3) The chlorine content was calculated by completely burning the rubber sample in a burning flask, absorbing the generated chlorine in water, and titrating with silver nitrate.

[ Ash content ]

The ash content (%) contained in the acrylic rubber sheet or the acrylic rubber bag was measured in accordance with JIS K6228A method.

[ ash component amount ]

For each component amount (ppm) in the acrylic rubber sheet or the acrylic rubber-coated ash, the ash collected at the time of the ash measurement was pressed against titration filter paper of Φ20mm, and XRF measurement was performed using ZSX Primus (manufactured by Rigaku Co.).

[ molecular weight and molecular weight distribution ]

The molecular weight (Mw, mn, mz) and the molecular weight distribution (Mw/Mn and Mz/Mw) of the acrylic rubber were measured by GPC-MALS method using solutions in which lithium chloride and 37% concentrated hydrochloric acid were added to dimethylformamide as a solvent, respectively, so that the concentration of lithium chloride was 5mol/L and the concentration of hydrochloric acid was 0.01%.

The gel permeation chromatography multi-angle light scattering photometer used as the device was constituted by a pump (manufactured by LC-20ADOpt corporation, shimadzu corporation), a differential refractometer (manufactured by Optilab rEX Wyatt Technology corporation) used as a detector, and a multi-angle light scattering detector (manufactured by DAWN HELEOS WyattTechnology corporation). Specifically, a multi-angle laser light scattering detector (MALS) and a differential refractometer detector (RI) were assembled in a GPC (gel permeation chromatography ) apparatus, and the molecular weight of a solute and its content were calculated in order by measuring the light scattering intensity and refractive index difference of a molecular chain solution classified by size according to elution time by the GPC apparatus. The measurement conditions and measurement methods using the GPC layer are as follows.

Column: TSKgel alpha-M2Root of Chinese Paris

Manufactured by Tosoh corporation

Column temperature: 40 DEG C

Flow rate: 0.8ml/mm

Sample preparation: to a 10mg sample (acrylic rubber sheet or acrylic rubber bag) was added 5ml of solvent, and the mixture was stirred slowly at room temperature (dissolution was visually confirmed). Then, filtration was performed using a 0.5 μm filter.

[ glass transition temperature (Tg) ]

The glass transition temperature (Tg) of the acrylic rubber was measured by using a differential scanning calorimeter (DSC, product name "X-DSC7000", manufactured by Hitachi Ltd.).

[ gel amount ]

The gel content (%) of the acrylic sheet or acrylic rubber bag was determined as the methyl ethyl ketone insoluble component content by the following method.

About 0.2g of an acrylic rubber sheet or acrylic rubber bag (Xg) was weighed, immersed in 100ml of methyl ethyl ketone, left at room temperature for 24 hours, and then, a methyl ethyl ketone-insoluble component was filtered using an 80-mesh metal mesh to obtain a filtrate, i.e., a filtrate in which only a methyl ethyl ketone-soluble rubber component was dissolved, and the filtrate was evaporated to dryness and solidified, and the obtained dry solid component (Yg) was weighed and calculated by the following formula.

Methyl ethyl ketone insoluble component amount (%) =100× (X-Y)/X

[ specific gravity ]

The specific gravity of the acrylic rubber sheet or acrylic rubber bag was measured according to the method A of JIS K6268 crosslinked rubber-density measurement.

The measured value obtained by the following measuring method was the density, and the density of water was 1Mg/m ³ Specific gravity at that time. Specifically, the specific gravity of the rubber sample obtained by the A method of JIS K6268 crosslinked rubber-Density measurement is obtained by dividing the mass of the rubber sample by the volume of voids containing the rubber sample, and is obtained by dividing the density of the rubber sample obtained by the A method of JIS K6268 crosslinked rubber-Density measurement by the density of water (when the rubber sample is The values are the same when the density is divided by the density of water, the unit vanishes). Specifically, the specific gravity of the rubber sample was determined based on the following procedure.

(1) From a rubber sample after standing at a standard temperature (23 ℃ C..+ -. 2 ℃ C.) for at least 3 hours, 2.5g of a test piece was cut out, and the test piece was hung on a hook on a chemical balance having an accuracy of 1mg using a fine nylon wire having a mass of less than 0.010g so that the bottom edge of the test piece was 25mm higher than a distribution plate for the chemical balance, and the mass (m 1) of the test piece was measured 2 times in the atmosphere to mg.

(2) Next, 250cm of the solution was placed on a distribution plate for a chemical balance ³ Distilled water cooled to a standard temperature after boiling was filled in a beaker having a capacity, a test piece was immersed therein, bubbles adhering to the surface of the test piece were removed, the movement of a pointer of a balance was observed for several seconds, it was confirmed that the pointer was not slowly swung by convection, and the mass (m 2) of the test piece in water was measured in mg units for 2 times.

(3) In addition, the density of the test piece is less than 1Mg/m ³ When (the test piece floats in water), a weight is added to the test piece, and the mass (m 3) of the weight in water and the mass (m 4) of the test piece and the weight are measured 2 times in mg.

(4) The specific gravity of the rubber sample was determined by using the average value of each of m1, m2, m3, and m4 determined as described above, and the density (Mg/m was calculated based on the following formula ³ ) And dividing the calculated density by the density of water (1.00 Mg/m ³ ) And (5) obtaining.

(Density of rubber sample without counterweight)

Density=m1/(m 1-m 2)

(Density of rubber sample when weight was used)

Density=m1/(m1+m3-m 4)

[ Water content ]

Moisture content (%) according to JIS K6238-1: the measurement was performed by the oven a (volatile component measurement) method.

[pH]

After dissolving 6g (+ -0.05 g) of an acrylic rubber sheet or an acrylic rubber bag with 100g of tetrahydrofuran, 2.0ml of distilled water was added thereto, and after confirming complete dissolution, the pH was measured with a pH electrode.

[ Complex viscosity ]

The complex viscosity η is obtained by measuring the temperature dispersion (40 to 120 ℃) under the conditions of the strain 473 and 1Hz using a dynamic viscoelasticity measuring device "Rubber Process Analyzer RPA-2000" (manufactured by alpha technologies Co., ltd.) and obtaining the complex viscosity η at each temperature. Here, the values of the ratios η (100 ℃) and η (60 ℃) were calculated using the dynamic viscoelasticity at 60℃as the complex viscosity η (60 ℃) and the dynamic viscoelasticity at 100℃as the complex viscosity η (100 ℃), among the dynamic viscoelasticity.

[ Mooney viscosity (ML1+4, 100 ℃)

Mooney viscosity (ML1+4, 100 ℃ C.) was measured according to the physical test method of uncrosslinked rubber in JIS K6300.

[ evaluation of deviation of gel amount ]

The evaluation of the deviation of the gel amount of the rubber sample was performed by measuring the gel amount at 20 points arbitrarily selected from 20 parts (20 kg) of the rubber sample based on the following criteria.

And (3) the following materials: calculating the average value of the gel amount at 20 points, wherein all the 20 points are within the range of +/-3 of the average value

O: calculating the average value of the gel amounts at 20 points of measurement, wherein all the 20 points of measurement are within the range of the average value + -5 (1 at 20 points of measurement is outside the range of the average value + -3, but all the 20 points are within the range of the average value + -5)

X: calculating the average value of the gel amount at 20 points, 1 of 20 points being outside the range of + -5

[ Cross-Linkability ]

The crosslinking property of the rubber sample was calculated, and the rate of change in the breaking strength of the crosslinked material subjected to the secondary crosslinking for 2 hours and the breaking strength of the crosslinked material subjected to the secondary crosslinking for 4 hours ((breaking strength of the crosslinked rubber material for 4 hours/breaking strength of the crosslinked rubber material for 2 hours). Times.100) was determined according to the following criteria.

And (3) the following materials: the change rate of the breaking strength is less than 10 percent

X: the change rate of the breaking strength is more than 10 percent

[ roll processability ]

For the roll processability of the rubber sample, the roll-windability and the rubber state when the rubber sample was rolled were observed and evaluated based on the following criteria.

And (3) the following materials: easy mixing, easy winding on the roller, no separation from the roller is observed, and the surface of the rubber composition after mixing is smooth

O: easy kneading, easy winding around the roll, no detachment from the roll, and slight irregularities on a part of the surface of the rubber composition after kneading

And ∈: easy kneading, excellent roll windability, and some irregularities on the surface of the rubber composition after kneading

Delta: easy mixing and poor roll-windability, and the surface of the rubber composition after mixing is rough

X: the roll windability is also poor when a load is applied during kneading

[ Banbury processability ]

For the banbury processability of the rubber sample, the rubber sample was put into a banbury mixer heated to 50 ℃ for 1 minute for mastication, and then compounding agent a blended in the rubber mixture described in table 1 was put into the first-stage rubber mixture to integrate the rubber mixture, and the time to show the maximum torque value, that is, BIT (carbon black mixing time, black Incorporation Time) was measured, and evaluated by an index of 100 in comparative example 2 (the smaller the index, the more excellent the processability).

[ evaluation of storage stability ]

For the storage stability of the rubber sample, the change rate of the water content before and after the test was calculated by putting the rubber sample into a constant temperature and humidity tank (SH-222 manufactured by espek) at 45 ℃ x 80% rh, and the evaluation was performed by using an index of 100 in comparative example 2 (the smaller the index, the more excellent the storage stability).

[ evaluation of Water resistance ]

For the water resistance of the rubber sample, the crosslinked product of the rubber sample was immersed in distilled water at 85℃for 100 hours in accordance with JIS K6258, the immersion test was performed, the volume change rate before and after immersion was calculated from the following formula, and the evaluation was performed by using an index of 100 in comparative example 2 (the smaller the index, the more excellent the water resistance).

Rate of change in volume (%) = ((volume of test piece after immersion-volume of test piece before immersion) before and after immersion

Test piece volume before immersion) ×100

[ compression set resistance ]

The compression set resistance of the rubber sample was measured in a state where the rubber crosslinked product of the rubber sample was compressed by 25% in accordance with JIS K6262, and the compression set after being left at 175℃for 90 hours was evaluated by the following criteria.

And (3) the following materials: compression set of less than 15%

X: compression set of 15% or more

[ evaluation of physical Properties in Normal state ]

For the normal physical properties of the rubber sample, the breaking strength, 100% tensile stress and elongation at break of the rubber crosslinked product of the rubber sample were measured in accordance with JIS K6251, and evaluated by the following criteria.

(1) For the breaking strength, 10MPa or more was evaluated as excellent, and less than 10MPa was evaluated as x.

(2) For 100% tensile stress, 5MPa or more was rated as excellent, and less than 5MPa was rated as X.

(3) Regarding the elongation at break, 150% or more was evaluated as × and less than 150% was evaluated as ×.

[ evaluation of processing stability based on inhibition of Mooney scorch ]

The mooney scorch stability of the acrylic rubber composition was evaluated for the cooling rate of the sheet-like acrylic rubber extruded from the screw type biaxial extrusion dryer described in japanese patent No. 6683189.

Example 1

As shown in Table 2-1, a mixing vessel having a homomixer was charged with 46 parts of pure water, 74.5 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of methoxyethyl acrylate and 1.5 parts of mono-n-butyl fumarate, 1.8 parts of sodium tridecyloxy hexaoxy ethylene phosphate as an emulsifier, and stirred to obtain a monomer emulsion.

170 parts of pure water and 3 parts of the monomer emulsion obtained above were charged into a polymerization reaction vessel equipped with a thermometer and a stirrer, and after cooling to 12℃under a nitrogen stream, 0.00033 parts of ferrous sulfate, 0.02 parts of sodium ascorbate, and 0.21 parts of potassium persulfate as an inorganic radical generator were charged to initiate polymerization. The polymerization reaction was continued by maintaining the temperature in the polymerization vessel at 23℃and dropping the remaining portion of the monomer emulsion for 3 hours, adding 0.017 part of n-dodecyl mercaptan after 50 minutes from the start of the reaction, adding 0.017 part of n-dodecyl mercaptan after 100 minutes, and adding 0.017 part of n-dodecyl mercaptan and 0.4 part of sodium L-ascorbate after 120 minutes, and when the polymerization conversion reached approximately 100%, adding hydroquinone as a polymerization terminator, and stopping the polymerization reaction to obtain an emulsion polymerization solution.

Next, in a coagulation tank having a thermometer and a stirring device, the emulsion polymerization solution obtained above was heated to 80 ℃, and 350 parts of a 2% magnesium sulfate aqueous solution (coagulation solution using magnesium sulfate as a coagulant) vigorously stirred at a stirring blade rotation speed of the stirring device of 600 revolutions (a circumferential speed of 3.1 m/s) was continuously added to coagulate the polymer, thereby obtaining a coagulated slurry containing aggregates of acrylic rubber as a coagulated material and water. The granules were filtered from the slurry obtained, and water was discharged from the solidified layer to obtain aqueous granules.

194 parts of hot water (70 ℃) was added to the coagulation tank in which the filtered aqueous pellets remained, the aqueous pellets were washed by stirring for 15 minutes, then the water was discharged, 194 parts of hot water (70 ℃) was added again, and the aqueous pellets were washed by stirring for 15 minutes (the total number of washing times was 2). The washed aqueous pellet (aqueous pellet temperature: 65 ℃ C.) was fed to a screw type biaxial extrusion dryer 15, dehydrated and dried, and a sheet-like dried rubber having a width of 300mm and a thickness of 10mm was extruded. Next, the sheet-like dry rubber was cooled at a cooling rate of 200 ℃/hr using a conveyor type cooling device provided in direct connection with the screw type biaxial extrusion dryer 15, to obtain an acrylic rubber sheet (a). The reactive group content, ash content, gel content, pH, specific gravity, glass transition temperature (Tg), water content, molecular weight distribution, and complex viscosity at 100℃and 60℃of the acrylic rubber sheet (A) were measured, and the results are shown in tables 2-2. Further, gel amount deviation and storage stability of the acrylic rubber sheet (a) were tested, and the water content change rate was obtained, and the results are shown in tables 2 to 2.

In addition, the screw type biaxial extrusion dryer used in this example 1 is composed of 1 supply cylinder, 3 dehydration cylinders (first to third dehydration cylinders), and 5 dryer cylinders (first to fifth dryer cylinders). The first dewatering cylinder discharges water, and the second and third dewatering cylinders discharge steam. The operating conditions of the screw type biaxial extrusion dryer are as follows. The post-dewatering (drainage) water content, maximum torque, specific power, specific energy consumption, shear rate and shear viscosity of the screw type biaxial extrusion dryer are shown in table 2-1.

Water content:

water content of the aqueous pellet after draining with the first dewatering barrel: 20 percent of

Water content of the aqueous pellets after steam venting with the third dewatering barrel: 10 percent of

Moisture content of the aqueous pellet after drying with the fifth dryer barrel: 0.4%

Rubber temperature:

temperature of the aqueous pellets fed to the feed barrel: 65 DEG C

Temperature of rubber discharged from screw type biaxial extrusion dryer: 140 DEG C

Set temperature of each barrel:

first dewatering barrel: 100 DEG C

A second dewatering barrel: 120 DEG C

Third dewatering barrel: 120 DEG C

First dryer barrel: 120 DEG C

Second dryer barrel: 130 DEG C

Third dryer barrel: 140 DEG C

Fourth dryer barrel: 160 DEG C

Fifth dryer barrel: 180 DEG C

Operating conditions:

diameter of screw (D): 132mm

Full length of screw (L): 4620mm

·L/D：35

Rotational speed of the screw: 135rpm

Degree of depressurization of the dryer barrel: 10kPa

Rubber extrusion amount from die: 700 kg/hr

Resin pressure of die: 2MPa of

Maximum torque in screw type biaxial extrusion dryer: 15 N.m

The extruded sheet-like dry rubber was cooled to 50℃and then cut by a cutting device, and 20 parts (20 kg) of the sheet-like dry rubber was laminated until the temperature reached 40℃or lower, to obtain an acrylic rubber bag (A). The reactive group content, ash component content, gel content, pH, specific gravity, glass transition temperature (Tg), water content, molecular weight distribution, and complex viscosity at 100℃and 60℃of the obtained acrylic rubber bag (A) were measured. Further, gel amount deviation and storage stability of the acrylic rubber bag (a) were tested to determine the water content change rate.

Next, 100 parts of the acrylic rubber sheet (A) and the compounding agent A of "compounding 1" shown in Table 1 were charged into the Banbury mixer, and mixed at 50℃for 5 minutes (first-stage mixing). BIT was measured at this time, and the Banbury processability of the acrylic rubber was evaluated, and the results are shown in Table 2-2.

Next, the obtained compound was transferred to a roller at 50℃to be compounded with the compounding agent B of "compounding 1", and mixed to obtain a rubber compound. The roll processability at this time was evaluated, and the results are shown in Table 2-2.

TABLE 1

1: in the table, seast 3 (HAF) is carbon black (manufactured by eastern sea carbon Co., ltd.).

2: NOCRAC CD in the tables is 4,4' -bis (. Alpha.,. Alpha. -dimethylbenzyl) diphenylamine (manufactured by Dain Ind.).

3: in the table

XLA-60 is a vulcanization accelerator (manufactured by Langsheng Co.).

The obtained rubber mixture was placed in a metal mold having a length of 15cm, a width of 15cm and a depth of 0.2cm, and was pressed at 180℃for 10 minutes while being pressurized by a pressing pressure of 10MPa, and then subjected to primary crosslinking, and the obtained primary crosslinked product was subjected to secondary crosslinking at 180℃for 2 hours using a Gill oven, to obtain a sheet-like crosslinked rubber product. Then, a test piece of 3cm X2 cm X0.2 cm was cut out from the resulting sheet-like rubber crosslinked material, and the water resistance, compression set resistance and normal physical properties were evaluated. Further, the physical properties of the sheet-like rubber crosslinked product which was further subjected to secondary crosslinking for 2 hours were measured in a normal state, and the crosslinkability was evaluated. These results are shown in Table 2-2.

Example 2

The same operations as in example 1 were conducted except that the monomer components were changed to 4.5 parts of ethyl acrylate, 64.5 parts of n-butyl acrylate, 29.5 parts of methoxyethyl acrylate and 1.5 parts of mono-n-butyl fumarate, and the emulsifier was changed to 1.8 parts of nonylphenoxy hexaoxyethylene phosphate sodium salt, to obtain an acrylic rubber sheet (B) and an acrylic rubber bag (B), and the respective properties were evaluated. The results of the acrylic rubber sheet (B) are shown in Table 2-2.

Example 3

The same operations as in example 1 were performed except that the amount of potassium persulfate was changed to 0.2 part, the post-addition of n-dodecyl mercaptan was changed to 0.0072 part after 50 minutes, and 0.0036 part after 100 minutes, to obtain an acrylic rubber sheet (C) and an acrylic rubber bag (C), and the respective properties were evaluated. The results of the acrylic rubber sheet (C) are shown in Table 2-2.

Example 4

The same operations as in example 3 were conducted except that the monomer components were changed to 4.5 parts of ethyl acrylate, 64.5 parts of n-butyl acrylate, 29.5 parts of methoxyethyl acrylate and 1.5 parts of mono-n-butyl fumarate, and the emulsifier was changed to 1.8 parts of sodium octoxyhexaoxyethylene phosphate, to obtain an acrylic rubber sheet (D) and an acrylic rubber bag (D), and the respective properties were evaluated. The results of the acrylic rubber sheet (D) are shown in Table 2-2.

Example 5

The same operations as in example 1 were conducted except that the monomer components were changed to 28 parts of ethyl acrylate, 38 parts of N-butyl acrylate, 27 parts of methoxyethyl acrylate, 5 parts of acrylonitrile and 2 parts of allyl glycidyl ether, and the maximum torque of the screw-type biaxial extrusion dryer was changed to 45n·m, to obtain an acrylic rubber sheet (E) and an acrylic rubber bag (E), and the respective characteristics were evaluated (the compounding agent was changed to "compounding 2"). The results of the acrylic rubber sheet (E) are shown in Table 2-2.

Example 6

The same operations as in example 5 were conducted except that the monomer components were changed to 48.5 parts of ethyl acrylate, 50 parts of n-butyl acrylate and 1.5 parts of mono-n-butyl fumarate, to obtain an acrylic rubber sheet (F) and an acrylic rubber bag (F), and the respective properties were evaluated (the compounding agent was changed to "compounding 1"). The results of the acrylic rubber sheet (F) are shown in Table 2-2.

Example 7

The same operations as in example 5 were conducted except that the monomer components were changed to 48.25 parts of ethyl acrylate, 50 parts of n-butyl acrylate and 1.75 parts of mono-n-butyl fumarate, to obtain an acrylic rubber sheet (G) and an acrylic rubber bag (G), and the respective properties were evaluated (the compounding agent was changed to "compounding 3"). The results of the acrylic rubber sheet (G) are shown in Table 2-2.

Example 8

The same operations as in example 3 were conducted except that the monomer components were changed to 28 parts of ethyl acrylate, 38 parts of N-butyl acrylate, 27 parts of methoxyethyl acrylate, 5 parts of acrylonitrile and 2 parts of allyl glycidyl ether, and the maximum torque of the screw-type biaxial extrusion dryer was changed to 45n·m, to obtain an acrylic rubber sheet (H) and an acrylic rubber bag (H), and the respective characteristics were evaluated (the compounding agent was changed to "compounding 2"). The results of the acrylic rubber sheet (H) are shown in Table 2-2.

Example 9

The same operations as in example 8 were conducted except that the monomer components were changed to 48.5 parts of ethyl acrylate, 50 parts of n-butyl acrylate and 1.5 parts of mono-n-butyl fumarate, to obtain an acrylic rubber sheet (I) and an acrylic rubber bag (I), and the respective properties were evaluated (the compounding agent was changed to "compounding 1"). The results of the acrylic rubber sheet (I) are shown in Table 2-2.

Example 10

An acrylic rubber sheet (J) and an acrylic rubber bag (J) were obtained in the same manner as in example 8 except that the monomer components were changed to 48.25 parts of ethyl acrylate, 50 parts of n-butyl acrylate and 1.75 parts of mono-n-butyl fumarate, and the respective properties were evaluated (the compounding agent was changed to "compounding 3"). The results of the acrylic rubber sheet (J) are shown in Table 2-2.

Comparative example 1

A mixing vessel having a homomixer was charged with 46 parts of pure water, 42.2 parts of ethyl acrylate as a monomer component, 35 parts of n-butyl acrylate, 20 parts of methoxyethyl acrylate, 1.5 parts of acrylonitrile and 1.3 parts of vinyl chloroacetate, and 1.8 parts of sodium tridecyloxy hexaoxyethylene phosphate as an emulsifier, and stirred to obtain a monomer emulsion.

170 parts of pure water and 3 parts of the monomer emulsion obtained above were charged into a polymerization reaction vessel equipped with a thermometer and a stirrer, and after cooling to 12℃under a nitrogen stream, 0.00033 parts of ferrous sulfate, 0.02 parts of sodium ascorbate, and 0.22 parts of potassium persulfate were charged to initiate polymerization. The temperature in the polymerization vessel was kept at 23℃and the remaining part of the monomer emulsion was added dropwise over 3 hours, and when the polymerization conversion reached approximately 100%, hydroquinone was added as a polymerization terminator to stop the polymerization reaction, thereby obtaining an emulsion polymerization solution.

Subsequently, the emulsion polymerization solution was heated to 80℃and stirred at a stirring blade rotation speed of 100 revolutions (circumferential speed of 0.5 m/s), and then a 0.7% aqueous magnesium sulfate solution (coagulation solution using magnesium sulfate as a coagulant) was added thereto to coagulate the polymer, thereby obtaining a coagulated slurry containing the pellets of the acrylic rubber as a coagulated material and water. The granules were filtered from the slurry obtained, and water was discharged from the solidified layer to obtain aqueous granules. 194 parts of hot water (70 ℃) was added to the coagulation tank in which the filtered aqueous pellets remained, stirred for 15 minutes, the aqueous pellets were washed, then the water was discharged, 194 parts of hot water (70 ℃) was added again, stirred for 15 minutes, and the aqueous pellets were washed (the total number of washing times was 2). The washed aqueous pellets were dried using a hot air dryer at 160℃until the water content reached 0.4%, to obtain a pellet-like acrylic rubber (K). The properties of the obtained pellet-like acrylic rubber (K) were evaluated, and are shown in Table 2-2.

Comparative example 2

The emulsifier was changed to 0.709 part of sodium lauryl sulfate and 1.82 parts of polyoxyethylene lauryl ether, the coagulation liquid was changed to 0.7% sodium sulfate aqueous solution, and the cleaning method was changed to the following cleaning method: the following aqueous pellets were washed 4 times, 194 parts of industrial water was added to 100 parts of the aqueous pellets after the coagulation reaction, and the aqueous pellets were stirred in a coagulation tank at 25℃for 5 minutes, and then the water was discharged from the coagulation tank; then, the following acid washing was performed 1 time, 194 parts of an aqueous sulfuric acid solution of pH3 was added, and the mixture was stirred at 25℃for 5 minutes, followed by draining the water from the coagulation tank; then, 194 parts of pure water was added to perform 1 pure water washing, and the same operation as in comparative example 1 was performed to obtain a pellet-like acrylic rubber (L). The properties of the obtained pellet-like acrylic rubber (L) were evaluated, and the results are shown in Table 2-2.

[ Table 2-1]

[ Table 2-2]

As is clear from tables 2-1 and 2-2, the acrylic rubber sheets (A) to (J) of the present invention, which were formed of an acrylic rubber having an ion-reactive group and having a ratio (Mz/Mw) of an absolute molecular weight distribution (z-average molecular weight) to a weight-average molecular weight (Mw) of 1.8 or more as measured by GPC-MALS method, were excellent in both processability, crosslinkability, compression set resistance and normal physical properties including strength characteristics, and further also significantly excellent in storage stability and water resistance, and had a gel content of 30 wt% or less.

It is also clear from tables 2 to 2 that, with respect to the acrylic rubber sheets (a) to (J) and the pellet-like acrylic rubbers (K) to (L) produced under the conditions of examples and comparative examples of the present invention, the absolute molecular weights (Mn, mw, mz) measured by GPC-MALS method, which have any one of the ion-reactive groups such as carboxyl groups, epoxy groups, chlorine atoms, and the like, also have a certain level of size, and therefore, both the crosslinking property in a short period of time, compression set resistance, and normal physical properties including strength characteristics are excellent (examples 1 to 10 and comparative examples 1 to 2). However, it was found that the gel amount deviation, roll processability and banbury processability of the pellet-like acrylic rubbers (K) to (L) were poor, and the storage stability and water resistance were also poor (comparative examples 1 to 2).

Regarding improvement of roll processability without impairing strength characteristics, it was found that it was possible to increase the ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) of the molecular weight distribution focusing on the polymer component (comparison of examples 1 to 10 and comparative examples 1 to 2). In addition, regarding the roll processability, it is found that the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) which is the molecular weight distribution in the low molecular weight region is preferably 3 or more, and further, the roll processability can be further improved by widening Mw/Mn (comparison of examples 1 to 4 with examples 5 to 10).

As is clear from tables 2-1 and 2-2, the acrylic rubber sheet having a very balanced strength characteristic and roll processability as described above can be produced by adding an inorganic radical generator in a small amount and adding a chain transfer agent (n-dodecyl mercaptan) in a batch-wise manner (examples 1 to 10). This is presumably because by reducing the amount of the inorganic radical generator to extend one polymer chain and adding a chain transfer agent (n-dodecyl mercaptan) after the batch, and combining the high molecular weight component with the low molecular weight component, the Mz/Mw in the high molecular weight region is increased, and the roll processability can be improved without impairing the strength characteristics. Further, it was found that the roll processability was further improved by drying the aqueous pellets under high shear (maximum torque 46 N.multidot.m) using a screw type biaxial extruder dryer to widen Mw/Mn (comparison of examples 1 to 4 with examples 5 to 10). In addition, although not shown in the data, it was confirmed that even if the pellet-like acrylic rubber (K) to (L) directly dried by hot air drying at 160 ℃ was dried by a screw type biaxial extrusion dryer under the condition of low shear (maximum torque 15n·m), the molecular weight and molecular weight distribution were hardly changed. In addition, although not shown in table 2-2, in the examples of the present invention, sodium ascorbate was added as a reducing agent 120 minutes after the start of polymerization, whereby a high molecular weight component of the acrylic rubber could be easily produced, and the strength characteristics and the roll processability characteristics could be highly balanced.

Regarding the Banbury processability, it is clear from Table 2-2 that the acrylic rubber sheets (A) to (J) of the present invention having extremely small gel amounts of components insoluble in methyl ethyl ketone are excellent (comparison of examples 1 to 10 with comparative examples 1 to 2). In the examples and comparative examples of the present invention, in order to improve the strength characteristics, emulsion polymerization was carried out until the polymerization conversion became approximately 100%, and the gel amount of the methyl ethyl ketone-insoluble component increased rapidly as the polymerization conversion became higher, and the banbury workability was deteriorated, but in the present invention, the rapidly increased methyl ethyl ketone-insoluble gel amount was eliminated by drying and melt kneading in a state substantially free of moisture (the moisture content was less than 1% by weight) using a screw type biaxial extrusion dryer, and the strength characteristics and banbury workability were highly balanced, and the gel amount of the methyl ethyl ketone-insoluble component was almost completely eliminated in the screw type biaxial extrusion dryer, so that the deviation in gel amount was almost not present, and the banbury workability and the crosslinking physical property were stabilized. In the examples of the present invention, although only extremely excellent data are shown, it was confirmed that BIT (carbon black mixing time, black Incorporation Time) which is an index of banbury processability and the gel amount of the methyl ethyl ketone-insoluble component were on a line of a very high correlation coefficient, for example, the same operation as in example 1 was performed until washing, and the obtained aqueous pellet was directly dried as in comparative example 1, and the gel amount of the methyl ethyl ketone-insoluble component of the obtained pellet-like acrylic rubber was 23 wt% and the banbury processability index was about 36. On the other hand, the same procedure as in comparative example 1 was carried out until washing, and the obtained aqueous pellets were dehydrated, dried and molded using a screw type biaxial extrusion dryer under the same conditions as in example 1, whereby the gel content of methyl ethyl ketone-insoluble components of the produced acrylic rubber sheet was reduced to 3.4% by weight and the banbury processability index was improved to about 24. That is, the method for reducing the gel amount of methyl ethyl ketone-insoluble components in the acrylic rubber sheet or the pellet-like acrylic rubber includes: the latter method is markedly superior to a method in which a chain transfer agent is added after the latter half of emulsion polymerization of an acrylic rubber, in which an aqueous pellet produced in a coagulation step is washed and then melt kneaded in a state substantially free of moisture (water content less than 1% by weight) by a screw type biaxial extrusion dryer, and then extrusion-dried.

Further, as is clear from tables 2 to 2, the acrylic rubber sheets (a) to (J) of the present invention are excellent in both processability, crosslinkability, compression set resistance and strength characteristics, as well as in storage stability (examples 1 to 10). The acrylic rubber sheets (A) to (J) of the present invention have a high specific gravity, that is, are free from air inclusion and have excellent storage stability. In the present invention, in order to prevent air from being mixed in the acrylic rubber sheet, the air existing in the acrylic rubber is removed under reduced pressure in the dryer cylinder section in the screw type biaxial extrusion dryer, and the melt kneading is performed in a state of substantially no moisture, and then the die section is rectified, the sheet-like dried rubber is extruded so as to limit the resin pressure of the die head, and the sheet-like dried rubber is cut and laminated at a specific temperature, whereby the specific gravity is increased, and the storage stability is remarkably improved (examples 1 to 10 are compared with comparative examples 1 to 2). The acrylic rubber sheet of the present invention also has a pH in a specific region of 3 to 6, which contributes to an improvement in storage stability (comparison of examples 1 to 10 with comparative example 2).

Further, as is clear from tables 2 to 2, the acrylic rubber sheets (a) to (J) of the present invention are excellent in both processability, crosslinkability, compression set resistance and strength characteristics, as well as in water resistance (examples 1 to 10). As is clear from tables 2 to 2, the acrylic rubber sheets (A) to (J) of the present invention and the acrylic rubber (K) to (L) of the comparative examples each have a total element amount of more than 90% by weight of phosphorus, magnesium, sodium, calcium and sulfur in ash, and the acrylic rubber bag is excellent in water resistance, mold releasability and other properties, and particularly as the ratio of phosphorus to magnesium in ash increases, the water resistance increases (examples 1 to 10 and comparative example 1).

As is clear from tables 2 to 2, the water resistance of the acrylic rubber was also greatly affected by the ash content. It is known that the ash amount in the acrylic rubber sheets (a) to (J) of the present invention can be greatly reduced by performing the following operations: the coagulation reaction is carried out by adding emulsion polymerization liquid after emulsion polymerization into coagulation liquid by using concentrated coagulant concentration and intense stirring; washing with hot water; and drying the dehydrated granules (comparative examples 1 to 10 and comparative examples 1 to 2). In addition, regarding the water resistance, by increasing the contents of phosphorus and magnesium in ash and the ratio of specific phosphorus to magnesium, the water resistance of the acrylic rubber can be greatly improved (examples 1 to 10 and comparison of comparative example 1 and comparative example 2). Here, it is assumed that, regarding coagulation in a vigorously stirred coagulation liquid, since the coagulation reaction is carried out by adding an emulsion polymerization liquid to a very vigorously stirred coagulation liquid having a circumferential velocity of 1m/s or more, although not shown in examples of the present invention, the aqueous aggregates generated in the coagulation method carried out in examples of the present invention are almost aggregated in a small particle size of 710 μm to 4.75mm, and therefore, the cleaning efficiency by hot water and the ash removal efficiency by dehydration are remarkably improved, and the water resistance of the acrylic rubber sheet of the present invention can be improved.

The evaluation of the properties of the acrylic rubber bags (a) to (J) of the present invention is not shown in tables 2 to 2, and is the same as that of the corresponding acrylic rubber sheets (a) to (J) of the present invention.

Regarding the acrylic rubber compositions comprising the acrylic rubber sheets (a) to (J) of examples 1 to 10, the mooney scorch storage stability was evaluated by the following criteria by measuring the mooney scorch time t5 (minutes) at a temperature of 125 ℃ in accordance with JIS K6300 by the above-described method for evaluating the processing stability based on suppression of mooney scorch. The results were excellent.

And (3) the following materials: the Mooney scorch time t5 is more than 2.0 minutes

O: the Mooney scorch time t5 is 1.5 to 2.0 minutes

X: the Mooney scorch time t5 is less than 1.5 minutes

In addition, the cooling rate of the sheet-like dry rubber extruded from the screw type biaxial extrusion dryer was as high as about 200 ℃/hr, which is 40 ℃/hr or more, as in example 1, with respect to the acrylic rubber sheets (a) to (J).

[ Release of Metal mold ]

The rubber compositions of the acrylic rubber sheets (A) to (J) obtained in examples 1 to 10 were pressed into

After crosslinking at 165℃for 2 minutes, the rubber crosslinked product was taken out, and the mold releasability was evaluated by the following criteria, and at this time, all of the acrylic rubber sheets (A) to (J) were evaluated to be excellent.

And (3) the following materials: easy release from metal mold without mold residue

O: is easy to release from the metal mold, but only trace mold residues are observed

Delta: is easy to release from the metal mold, but has a small amount of mold residues

X: difficult to separate from the metal mold

Description of the reference numerals

1: an acrylic rubber manufacturing system;

3: a coagulation device;

4: a cleaning device;

5: a screw extruder;

6: a cooling device;

7: and a glue wrapping device.

Claims

1. An acrylic rubber sheet having an ion-reactive group,

the acrylic rubber sheet has a ratio (Mz/Mw) of a z-average molecular weight (Mz) to a weight-average molecular weight (Mw) of an absolute molecular weight distribution measured by GPC-MALS method of 1.8 or more,

the gel amount of the acrylic rubber sheet is 30% by weight or less.

2. The acrylic rubber sheet according to claim 1, wherein the acrylic rubber sheet has a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of an absolute molecular weight distribution measured by GPC-MALS method of 3.5 or more.

3. The acrylic rubber sheet according to claim 1 or 2, wherein the acrylic rubber sheet has a number average molecular weight (Mn) of an absolute molecular weight in a range of 10 to 50 tens of thousands as measured by GPC-MALS method.

4. The acrylic rubber sheet according to any one of claims 1 to 3, wherein the acrylic rubber sheet has a weight average molecular weight (Mw) of 100 to 350 ten thousand as measured by GPC-MALS method.

5. The acrylic rubber sheet according to any one of claims 1 to 4, wherein the measuring solvent of the GPC-MALS method is a dimethylformamide-based solvent.

6. The acrylic rubber sheet according to any one of claims 1 to 5, wherein the gel amount of the acrylic rubber sheet is 15% by weight or less.

7. The acrylic rubber sheet according to any one of claims 1 to 6, wherein the gel amount of the acrylic rubber sheet is a methyl ethyl ketone insoluble component amount.

8. The acrylic rubber sheet according to any one of claims 1 to 7, wherein the acrylic rubber is composed of a binding unit derived from a (meth) acrylate, a binding unit derived from an ion-reactive group-containing monomer, and a binding unit derived from another monomer,

the (meth) acrylic acid ester is at least one selected from the group consisting of alkyl (meth) acrylates and alkoxyalkyl (meth) acrylates.

9. The acrylic rubber sheet according to any one of claims 1 to 8, wherein an ash content of the acrylic rubber sheet is 1% by weight or less.

10. The acrylic rubber sheet according to any one of claims 1 to 9, wherein the total amount of sodium, magnesium, calcium, phosphorus and sulfur in ash of the acrylic rubber sheet is 50% by weight or more.

11. The acrylic rubber sheet according to any one of claims 1 to 10, wherein the acrylic rubber sheet has a complex viscosity ([ η60 ] c) of 15000[ pa-s ] or less at 60 ℃.

12. The acrylic rubber sheet according to any one of claims 1 to 11, wherein a ratio of complex viscosity at 100 ℃ ([ η100 ℃) to complex viscosity at 60 ℃ ([ η60 ℃) ([ η100 ℃/[ η60 ℃)) is 0.8 or more.

13. The acrylic rubber sheet according to any one of claims 1 to 12, wherein the pH of the acrylic rubber sheet is in the range of 3 to 6.

14. The acrylic rubber sheet according to any one of claims 1 to 13, wherein the acrylic rubber sheet is a melt-kneaded sheet.

15. The acrylic rubber sheet according to any one of claims 1 to 14, wherein the content of the acrylic rubber in the acrylic rubber sheet is 90% by weight or more.

16. The acrylic rubber sheet according to any one of claims 1 to 15, wherein the acrylic rubber sheet is emulsion-polymerized using a phosphate salt or a sulfate salt as an emulsifier.

17. The acrylic rubber sheet according to any one of claims 1 to 16, wherein the acrylic rubber sheet is obtained by solidifying a polymerization liquid after emulsion polymerization using an alkali metal salt or a group 2 metal salt of the periodic table as a coagulant, and drying the solidified polymerization liquid.

18. The acrylic rubber sheet according to any one of claims 1 to 17, wherein the acrylic rubber sheet is obtained by melt kneading and drying after solidification.

19. The acrylic rubber sheet according to claim 18, wherein the melt-kneading and drying are performed in a state substantially free of moisture.

20. The acrylic rubber sheet according to claim 18 or 19, wherein the melt-kneading and drying are performed under reduced pressure.

21. The acrylic rubber sheet according to any one of claims 18 to 20, wherein after the melt-kneading and drying, cooling is performed at a cooling rate of 40 ℃/hr or more.

22. A method for producing an acrylic rubber sheet, comprising the steps of:

an emulsifying step of emulsifying an acrylic rubber monomer component containing an ion-reactive group-containing monomer with water and an emulsifier;

an emulsion polymerization step of initiating a polymerization reaction in the presence of a redox catalyst comprising an inorganic radical generator and a reducing agent, adding a chain transfer agent after the batch during the polymerization, and continuing the polymerization to obtain an emulsion polymerization solution;

A coagulation step of coagulating the emulsion polymerization liquid obtained with a coagulating liquid to produce an aqueous pellet;

a cleaning step of cleaning the produced aqueous pellets;

a dehydration step of dehydrating the washed aqueous pellets to a water content of 1 to 40 wt% by using a dehydration cylinder having a dehydration slit, a dryer cylinder under reduced pressure, and a screw type biaxial extrusion dryer having a die at the tip end;

a drying step of drying the mixture to less than 1% by weight with a dryer; and

and a molding step of extruding the sheet-like dry rubber from the die.

23. The method for producing an acrylic rubber sheet according to claim 22, wherein the acrylic rubber sheet according to any one of claims 1 to 21 is produced.

24. The method for producing an acrylic rubber sheet according to claim 22 or 23, wherein a maximum torque of the screw type biaxial extrusion dryer is 25 n.m or more.

25. The method for producing an acrylic rubber sheet according to any one of claims 22 to 24, wherein the reducing agent is added later.

26. The method for producing an acrylic rubber sheet according to any one of claims 22 to 25, wherein emulsion polymerization is performed using a phosphate salt or a sulfate salt as an emulsifier in the emulsion polymerization step.

27. The method for producing an acrylic rubber sheet according to any one of claims 22 to 26, wherein the polymerization liquid produced in the emulsion polymerization step is coagulated by using an alkali metal salt or a group 2 metal salt of the periodic table as a coagulant, and dried.

28. The method for producing an acrylic rubber sheet according to claim 27, wherein the polymerization liquid produced in the emulsion polymerization step is added to an aqueous solution containing a coagulant containing an alkali metal salt or a group 2 metal salt of the periodic table and stirred to be coagulated.

29. The method for producing an acrylic rubber sheet according to any one of claims 22 to 28, wherein the polymerization liquid produced in the emulsion polymerization step is brought into contact with a coagulant to solidify, and then melt kneaded and dried.

30. The method for producing an acrylic rubber sheet according to claim 29, wherein the melt kneading and drying are performed in a state substantially free of moisture.

31. The method for producing an acrylic rubber sheet according to claim 29 or 30, wherein the melt kneading and drying are performed under reduced pressure.

32. The method for producing an acrylic rubber sheet according to any one of claims 29 to 31, wherein the acrylic rubber after melt-kneading and drying is cooled at a cooling rate of 40 ℃/hr or more.

33. An acrylic rubber bag, wherein the acrylic rubber bag is formed by laminating the acrylic rubber sheets according to any one of claims 1 to 21.

34. The acrylic rubber bag according to claim 33, wherein the values at the time of the deviation are measured with respect to the gel amount in the acrylic rubber bag by arbitrarily taking a plurality of samples, all of which are measured within a range of (average ± 5% by weight).

35. The acrylic rubber bag of claim 34, wherein the plurality of samples is 20 samples.

36. The acrylic rubber bag according to any one of claims 33 to 35, wherein the acrylic rubber bag has a specific gravity of 0.8 or more.

37. A rubber mixture comprising the acrylic rubber sheet of any one of claims 1 to 21 and/or the acrylic rubber package of any one of claims 33 to 36, a filler, and a crosslinking agent.

38. The rubber compound according to claim 37, wherein the filler is a reinforcing filler.

39. The rubber mixture of claim 37, wherein the filler is a carbon black.

40. The rubber mixture of claim 37, wherein the filler is a silica type.

41. The rubber compound according to any one of claims 37 to 40, wherein the cross-linking agent is an organic cross-linking agent.

42. The rubber compound of any of claims 37-41, wherein the cross-linking agent is a multi-component compound.

43. The rubber compound of any of claims 37-42, wherein the cross-linking agent is an ionically cross-linking compound.

44. A rubber compound as in claim 43, wherein the crosslinking agent is an ionically crosslinkable organic compound.

45. A rubber mixture as described in claim 43 or 44, wherein said crosslinking agent is a polyionic organic compound.

46. The rubber compound as claimed in any of claims 43 to 45, wherein,

the ion of the ion-crosslinkable compound, ion-crosslinkable organic compound or polyion-crosslinkable organic compound as the crosslinking agent is at least one ion-reactive group selected from the group consisting of an amino group, an epoxy group, a carboxyl group and a thiol group.

47. A rubber compound as defined in claim 45, wherein said crosslinking agent is at least one polyionic compound selected from the group consisting of polyamine compounds, polyepoxide compounds, polycarboxylic acid compounds, and polythiol compounds.

48. The rubber mixture according to any one of claims 37 to 47, wherein the content of the crosslinking agent is in the range of 0.001 to 20 parts by weight relative to 100 parts by weight of the rubber component.

49. The rubber mixture of any one of claims 37-48, wherein the rubber mixture further comprises an anti-aging agent.

50. The rubber compound of claim 49, wherein the anti-aging agent is an amine-based anti-aging agent.

51. A process for producing a rubber mixture, comprising mixing a rubber component comprising the acrylic rubber sheet of any one of claims 1 to 21 or the acrylic rubber bag of any one of claims 33 to 36, a filler, and an antioxidant, if necessary, and then mixing a crosslinking agent.

52. A crosslinked rubber product obtained by crosslinking the rubber mixture according to any one of claims 37 to 50.

53. A rubber crosslinked according to claim 52 wherein the crosslinking of the rubber mixture is performed after molding.

54. A rubber crosslinked according to claim 52 or 53 wherein the crosslinking of the rubber mixture is a crosslinking that is a primary crosslinking and a secondary crosslinking.