JP6741177B1 - Acrylic rubber sheet with excellent storage stability and water resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic rubber sheet excellent in storage stability and water resistance, and a method for producing the same. SOLUTION: This is composed of acrylic rubber whose main component is (meth)acrylic acid ester and whose weight average molecular weight (Mw) is in a specific range, and whose ash content is 0.8% by weight or less. An acrylic rubber sheet having a total amount of 30% by weight or more and a weight ratio of magnesium to phosphorus ([Mg]/[P]) of 0.4 to 2.5 has storage stability and water resistance. Excellent in performance. [Selection diagram] None

Description

The present invention relates to an acrylic rubber sheet and a method for producing the same, an acrylic rubber veil, a rubber mixture, and a rubber crosslinked product, and more specifically, an acrylic rubber sheet having excellent storage stability and water resistance, a method for producing the same, and the acrylic rubber sheet. The present invention relates to a laminated acrylic rubber veil, a rubber mixture obtained by mixing the acrylic rubber sheet and the acrylic rubber veil, and a rubber crosslinked product obtained by crosslinking the rubber mixture.

Acrylic rubber is a polymer containing acrylic acid ester as a main component, is generally known as a rubber having excellent heat resistance, oil resistance and ozone resistance, and is widely used in fields related to automobiles.

Such an acrylic rubber is usually obtained by emulsion-polymerizing a monomer component constituting the acrylic rubber, bringing the obtained emulsion-polymerized liquid into contact with a coagulant, and drying the resulting water-containing crumb, and then forming a crumb composed of dry rubber. It is commercialized as a sheet, sheet or veil.

Regarding such an acrylic rubber, for example, in Patent Document 1 (JP-A-50-156559), an acrylate monomer, a halogen-containing monomer, a monomer component composed of β-cyanoalkyl acrylate, water, and an alkyl as an emulsifier are described. After phenoxypoly(ethyleneoxy)ethyl phosphate was mixed and emulsified, paramenthane hydroperoxide was added to carry out emulsion polymerization, and the emulsion polymerization liquid was solidified and isolated using a 2% by weight solution of magnesium sulfate. A method for producing a crumb-shaped acrylic rubber by washing three times with hot water at 80° C. and drying under vacuum is disclosed. However, in the emulsion polymerization reaction and coagulation reaction using a monovalent phosphoric acid ester as an emulsifier in this method, stable emulsion or crumb formation is difficult, and a large amount of deposits are deposited in the polymerization tank or the coagulation tank, resulting in poor productivity. Further, even if the generated crumb is washed, the coagulant and the emulsifier remaining in the acrylic rubber cannot be sufficiently removed/reduced, and there is a problem that the obtained rubber product is inferior in storage stability and water resistance. In addition, the produced crumb-shaped acrylic rubber has a problem that it is inferior in workability and storage stability because of its strong adhesiveness.

Further, in Patent Document 2 (International Publication No. 2018/101146 pamphlet), a monomer component composed of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, and monoethyl fumarate, water, and poly as an emulsifier are disclosed. Charge oxyalkylene alkyl ether phosphate ester, add sodium ascorbate and potassium persulfate, and carry out emulsion polymerization reaction under atmospheric pressure and normal temperature. Coagulate the emulsion polymerization liquid with sodium sulfate aqueous solution, wash with water and dry to form crumb-like acrylic. A method of making rubber is disclosed. However, the crumb-like acrylic rubber obtained by this method has a problem that it is inferior in storage stability and water resistance, and also has strong tackiness and inferior workability.

Further, in Patent Document 3 (International Publication No. 2018/079783 pamphlet), a monomer component composed of ethyl acrylate, n-butyl acrylate, and mono-n-butyl fumarate is used as pure water, sodium lauryl sulfate, and polyoxy. Emulsification using an emulsifier consisting of ethylene dodecyl ether, emulsion polymerization in the presence of a polymerization initiator up to a polymerization conversion rate of 95% by weight to obtain an emulsion polymerization liquid, and sodium sulfate is continuously added thereto to obtain a hydrous crumb. Then, the hydrous crumbs are washed with industrial water 4 times, pH 3 acid washed 1 time, and pure water washing 1 time, and then dried at 110° C. for 1 hour in a hot air dryer. Discloses a method of obtaining an acrylic rubber excellent in water resistance (volume change after immersion in 80° C. distilled water for 70 hours) with a small residual amount of an emulsifier or a coagulant. However, recently, a higher degree of water resistance has been required for acrylic rubber, and in many cases, the requirement cannot be satisfied. In addition, Patent Document 3 does not describe that the acrylic rubber is used after being molded into a sheet shape or a veil shape, and it is assumed that the adhesive acrylic rubber is handled in a crumb shape. Had a problem of poor workability and storage stability.

On the other hand, regarding sheet rubber, for example, in Patent Document 4 (JP-A-1-225512), a twin-screw extruder including a feed barrel, a dewatering barrel, a standard barrel, a vent barrel, and a vacuum barrel is used. Nitrile rubber (NBR) crumb with a water content of about 50% is supplied to the feed barrel, most of the water content is dehydrated in the dehydration barrel, and the residual water content and vaporized substances are suctioned off in the vacuum barrel, and then the breaker plate and the die section are used. A method of continuously extruding into a strip is disclosed. Further, it is described that a rubber crumb such as acrylic rubber is used as the rubber crumb to which this method is applied. However, Patent Document 4 does not describe an acrylic rubber sheet excellent in storage stability and water resistance and a method for obtaining the same.

JP-A-50-156559 International Publication No. 2018/101146 Pamphlet International Publication No. 2018/079783 Pamphlet JP-A 1-225512

The present invention has been made in view of the above problems, an acrylic rubber sheet having excellent storage stability and water resistance and an efficient method for producing the same, and a rubber mixture produced from the acrylic rubber sheet and crosslinking the same. The object of the present invention is to provide a rubber cross-linked product.

As a result of intensive studies in view of the above problems, the present inventors have made a (meth)acrylic acid ester as a main component of an acrylic rubber having a specific molecular weight, and at a specific ash content, the proportion of magnesium and phosphorus in the ash is high. Moreover, it has been found that an acrylic rubber sheet in which both are in a specific ratio has remarkably excellent storage stability and water resistance.

On the other hand, the inventors of the present invention also found that an acrylic rubber sheet containing ash having a large ratio of magnesium to phosphorus due to insufficient cleaning of the coagulant and an acrylic rubber sheet containing ash containing many monovalent metals such as phosphorus and sodium. The storage stability and water resistance are deteriorated, and further, the effect of the present invention that is excellent in storage stability and water resistance is due to the complex viscosity, specific gravity, gel amount, pH, glass transition of the acrylic rubber sheet at a specific temperature. It was found that the characteristic values such as temperature (Tg) and Mooney viscosity can be remarkably improved by setting them in a specific range.

The present inventors have also found that such an acrylic rubber sheet is obtained by emulsion-polymerizing a monomer component containing a (meth)acrylic acid ester as a main component in the presence of a divalent phosphoric acid emulsifier to coagulate an emulsion polymerization liquid with a magnesium salt. The water-containing crumbs produced in this way can be easily manufactured by dewatering, drying, and molding with a specific screw-type extruder after washing and extruding a sheet-shaped dried product.Furthermore, this acrylic rubber sheet is used for the production of acrylic rubber veils. It has been found that it is not only particularly suitable for use as a rubber composition, but also can be used as a good rubber mixture and a rubber crosslinked product.

The present inventors can further adjust the shape and crumb diameter of the hydrous crumb to be produced by selecting the addition method of the coagulation reaction, the coagulation liquid concentration, the coagulation liquid temperature, the coagulant rotation speed and the peripheral speed in a specific range. Moreover, most of the coagulants used can be removed by washing those hydrous crumbs with warm water. On the other hand, the phosphate emulsifier causes salt exchange when the coagulation reaction is performed with the magnesium coagulant, and magnesium phosphate as a magnesium phosphate salt in the crumb. The magnesium phosphate can be effectively removed by squeezing (dehydrating) water from the water-containing crumb, and it can be removed by a specific screw type extruder. It was found that the gel amount in the resulting acrylic rubber can be reduced, an acrylic rubber sheet having a large specific gravity that does not entrap air, and having significantly improved storage stability and water resistance can be produced.

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

Thus, according to the present invention, an acrylic rubber having a weight average molecular weight (Mw) of (meth)acrylic acid ester as a main component and having a weight average molecular weight (Mw) of 100,000 to 5,000,000 and having an ash content of 0.8% by weight or less, The total amount of magnesium and phosphorus in the ash is 30% by weight or more with respect to the total amount of ash, and the ratio of magnesium to phosphorus ([Mg]/[P]) is 0.4 to 2. Acrylic rubber sheets, in the range of 5, are provided.

In the acrylic rubber sheet of the present invention, the acrylic rubber is at least one (meth)acrylic acid ester and a crosslinkable monomer selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester. In addition, it is preferably formed from other copolymerizable monomer used as necessary. In addition, in this invention, "(meth)acrylic acid ester" is used as a general term for esters of acrylic acid and/or methacrylic acid.

In the acrylic rubber sheet of the present invention, the complex viscosity at 60° C. ([η] 60° C.) is preferably 15,000 Pa·s or less.

In the acrylic rubber sheet of the present invention, the ratio ([η]100°C/[η]60°C) of the complex viscosity at 100°C ([η]100°C) to the complex viscosity at 60°C ([η]60°C). ) Is preferably 0.5 or more.

In the acrylic rubber sheet of the present invention, the specific gravity is preferably in the range of 0.7 to 1.5.

In the acrylic rubber sheet of the present invention, the gel amount is preferably 50% by weight or less.

In the acrylic rubber sheet of the present invention, the pH is preferably 6 or less.

In the acrylic rubber sheet of the present invention, the glass transition temperature (Tg) is preferably 20° C. or lower.

In the acrylic rubber sheet of the present invention, the Mooney viscosity (ML1+4,100° C.) is preferably in the range of 10 to 150.

According to the present invention, also, (meth) emulsified to obtain a single-mer component mainly composed of acrylic acid ester emulsion polymerization in the presence of emulsification and polymerization catalyst with water and divalent phosphate emulsifier polymer emulsion A polymerization step, a coagulation step of contacting the obtained emulsion polymerization liquid with an aqueous magnesium salt solution as a coagulant to generate hydrous crumbs, a washing step of washing the hydrous crumbs formed, and a dehydrated slit of the washed hydrous crumbs. A sheet having a water content of 1 to 40% by weight in a dehydration barrel using a screw-type extruder having a dehydration barrel having a dry barrel, a drying barrel under reduced pressure, and a die at its tip, and then drying to less than 1% by weight in a drying barrel. Provided is a method for producing an acrylic rubber sheet, which comprises a dehydration/drying/molding step of extruding dry rubber from a die.

In the method for producing an acrylic rubber sheet of the present invention, the emulsion polymerization liquid and the magnesium salt aqueous solution are brought into contact with each other to coagulate the polymer of the rubber. At this time, the emulsion polymerization liquid is added to the stirred magnesium salt aqueous solution. It is preferably performed.

The rotational speed of the stirred magnesium salt aqueous solution is preferably 100 rpm or more, and the peripheral speed of the stirred magnesium salt aqueous solution is preferably 0.5 m/s or more.

In the present invention, the number of revolutions of the aqueous solution of magnesium salt is represented by the number of revolutions of the stirring blade of the stirrer provided in the coagulation tank containing the aqueous solution of magnesium salt, and the peripheral speed is represented by the rotational linear velocity of the outer circumference of the stirring blade.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable to wash the hydrous crumb obtained in the coagulation step with warm water, particularly 40° C. or higher in the washing step.

In the method for producing an acrylic rubber sheet of the present invention, at least one or two or more of the following conditions (a) to (e) may be satisfied in the dehydration/drying/molding process using a screw type extruder. It is preferable to optimally satisfy all the conditions.
(A) The rotation speed (N) of the screw type extruder is in the range of 10 to 1,000 rpm. (b) The extrusion rate (Q) of the screw type extruder is 100 to 1,500 kg/hr. (C) The temperature of the drying barrel of the screw type extruder is in the range of 100 to 250° C. (d) The degree of pressure reduction of the drying barrel of the screw type extruder is in the range of 1 to 50 kPa (e ) The resin pressure of the die of the screw type extruder is in the range of 0.1 to 10 MPa.

According to the present invention, there is provided an acrylic rubber veil obtained by laminating the above acrylic rubber sheets.

According to the present invention, there is provided a rubber mixture obtained by mixing the acrylic rubber sheet or the acrylic rubber veil with a filler and a crosslinking agent. According to the present invention, a rubber cross-linked product obtained by cross-linking the above rubber mixture is further provided.

According to the present invention, an acrylic rubber sheet excellent in storage stability and water resistance and a method for efficiently producing the same are provided, and further, an acrylic rubber excellent in storage stability and water resistance obtained from the acrylic rubber sheet. A rubber mixture and a rubber cross-linked product having a veil and good properties are provided.

It is a figure which shows typically an example of the acrylic rubber manufacturing system used for manufacture of the acrylic rubber sheet which concerns on one Embodiment of this invention. It is a figure which shows the structure of the screw type extruder of FIG. It is a figure which shows the structure of the conveyance type cooling device used as a cooling device of FIG.

The acrylic rubber sheet of the present invention is made of acrylic rubber having a (meth)acrylic acid ester as a main component and a weight average molecular weight (Mw) of 100,000 to 5,000,000, and an ash content of 0.8% by weight or less, The total amount of magnesium and phosphorus in the ash is 30% by weight or more with respect to the total amount of ash, and the ratio of magnesium to phosphorus ([Mg]/[P]) is 0.4 to 2. It is characterized in that the range is 5.

<Monomer component>
The acrylic rubber constituting the acrylic rubber sheet of the present invention contains (meth)acrylic acid ester as a main component. The proportion of the (meth)acrylic acid ester in the acrylic rubber is appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more. It is preferable that the acrylic rubber constituting the acrylic rubber sheet of the present invention contains a reactive monomer because it can highly improve heat resistance, compression set resistance and the like.

Specific examples of the acrylic rubber containing a (meth)acrylic acid ester as a main component are appropriately selected according to the purpose of use and are not particularly limited, but include (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester. It is preferable to use at least one (meth)acrylic acid ester selected from the group consisting of, a reactive monomer, and any other copolymerizable monomer used if necessary.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group usually having 1 to 12 carbon atoms, preferably a (meth)acrylic acid alkyl ester having alkyl having 1 to 8 carbon atoms, More preferably, it is a (meth)acrylic acid alkyl ester having an alkyl group having 2 to 6 carbon atoms.

Specific examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylic acid n. -Butyl, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate and the like, ethyl (meth)acrylate, (meth)acrylic N-Butyl acid is preferable, and ethyl acrylate and n-butyl acrylate are more preferable.

As the (meth)acrylic acid alkoxyalkyl ester, a (meth)acrylic acid alkoxyalkyl ester having usually 2 to 12 alkoxyalkyl groups, preferably a (meth)acrylic acid alkoxyalkyl ester having 2 to 8 alkoxyalkyl groups is used. , And more preferably (meth)acrylic acid alkoxy ester having an alkoxyalkyl group having 2 to 6 carbon atoms.

Specific examples of such (meth)acrylic acid alkoxyalkyl ester include methoxymethyl (meth)acrylic acid, methoxyethyl (meth)acrylic acid, methoxypropyl (meth)acrylic acid, methoxybutyl (meth)acrylic acid, (meth) Examples thereof include ethoxymethyl acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and the like. Among these, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and the like are preferable, and methoxyethyl acrylate and ethoxyethyl acrylate are more preferable.

At least one kind of (meth)acrylic acid ester selected from the group consisting of these (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester is used alone or in combination of two or more kinds. The proportion in the rubber is usually 50% by weight or more, preferably 70 to 99.9% by weight, more preferably 80 to 99.5% by weight, and particularly preferably 87 to 99% by weight. If the amount of the (meth)acrylic acid ester in the monomer component is too small, the resulting acrylic rubber may have poor weather resistance, heat resistance, and oil resistance, which is not preferable.

On the other hand, the reactive monomer is not particularly limited and may be appropriately selected depending on the purpose of use, for example, at least one functional group selected from the group consisting of a carboxyl group, an epoxy group and a halogen group. The monomer having is preferable, and the monomer having a carboxyl group is particularly preferable. Further, in order to highly enhance water resistance, a monomer having an ion-reactive group such as a carboxyl group or an epoxy group is suitable.

As the monomer having a carboxyl group, ethylenically unsaturated carboxylic acid can be preferably used. Examples of the ethylenically unsaturated carboxylic acid include, for example, ethylenically unsaturated monocarboxylic acid, ethylenically unsaturated dicarboxylic acid, ethylenically unsaturated dicarboxylic acid monoester, and among these, particularly ethylenically unsaturated dicarboxylic acid monoester. It is preferable that the ester can further improve the compression set resistance when the acrylic rubber is a rubber cross-linked product.

The ethylenically unsaturated monocarboxylic acid is preferably an ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms, and examples thereof include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid and the like. be able to. The ethylenically unsaturated dicarboxylic acid is preferably an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms, and examples thereof include butenedioic acid such as fumaric acid and maleic acid, itaconic acid, citraconic acid, and chloromaleic acid. Can be mentioned. The ethylenically unsaturated dicarboxylic acid referred to here also includes those which are present as an anhydride.

The ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, but is usually an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and an alkyl monoester having 1 to 12 carbon atoms, preferably 4 to 12 carbon atoms. It is an ethylenically unsaturated dicarboxylic acid having 6 carbon atoms and an alkyl monoester having 2 to 8 carbon atoms, and more preferably an alkyl monoester having 2 to 6 carbon atoms butenedioic acid having 4 carbon atoms.

Specific examples of such ethylenically unsaturated dicarboxylic acid monoesters include monomethyl fumarate, monoethyl fumarate, mono-n-butyl fumarate, monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monocyclopentyl fumarate, Butenedioic acid monoalkyl esters such as monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate; etc. Acid monoalkyl ester; and the like. Among these, 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)acrylic acid esters such as glycidyl (meth)acrylate; epoxy group-containing vinyl ethers such as allyl glycidyl ether and vinyl glycidyl ether; and the like.

The halogen group of the monomer having a halogen group is not particularly limited, but is preferably a chlorine atom. Examples of the monomer having a halogen group include unsaturated alcohol ester of halogen-containing saturated carboxylic acid, (meth)acrylic acid haloalkyl ester, (meth)acrylic acid haloacyloxyalkyl ester, (meth)acrylic acid (haloacetyl Examples thereof include carbamoyloxy)alkyl ester, halogen-containing unsaturated ether, halogen-containing unsaturated ketone, halomethyl group-containing aromatic vinyl compound, halogen-containing unsaturated amide, and haloacetyl group-containing unsaturated monomer. Specific examples of unsaturated alcohol esters of these halogen-containing saturated carboxylic acids include vinyl chloroacetate, vinyl 2-chloropropionate, allyl chloroacetate and the like.

Specific examples of the (meth)acrylic acid haloalkyl ester include chloromethyl (meth)acrylic acid, 1-chloroethyl (meth)acrylic acid, 2-chloroethyl (meth)acrylic acid, and 1,2-dichloroethyl (meth)acrylic acid. , 2,3-dichloropropyl (meth)acrylate and the like.

Specific examples of the haloacyloxyalkyl (meth)acrylate include 2-(chloroacetoxy)ethyl (meth)acrylate, 2-(chloroacetoxy)propyl (meth)acrylate, and 3-(chloro)(meth)acrylate. Examples thereof include acetoxy)propyl and 3-(hydroxychloroacetoxy)propyl (meth)acrylate. Specific examples of the (meth)acrylic acid (haloacetylcarbamoyloxy)alkyl ester include 2-(chloroacetylcarbamoyloxy)ethyl (meth)acrylate and 3-(chloroacetylcarbamoyloxy)propyl (meth)acrylate. Can be mentioned.

Specific examples of the halogen-containing unsaturated ether 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 halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, and 2-chloroethyl allyl ketone.

Further, specific examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, p-chloromethyl-α-methylstyrene and the like. Further, specific examples of the halogen-containing unsaturated amide include N-chloromethyl(meth)acrylamide.

Further, specific examples of the haloacetyl group-containing unsaturated monomer include 3-(hydroxychloroacetoxy)propyl allyl ether and p-vinylbenzyl chloroacetic acid ester.

In the present invention, a radical reactive monomer can also be used as the reactive monomer, and specific examples thereof include a diene monomer. Examples of the diene monomer include conjugated dienes and non-conjugated dienes. Examples of the conjugated diene include 1,3-butadiene, isoprene, piperylene and the like. Examples of the non-conjugated diene include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth)acrylate, 2-dicyclopentadienylethyl (meth)acrylate, and the like.

These reactive monomers are used alone or in combination of two or more, and the ratio of the reactive monomer in the acrylic rubber is usually 0.01 to 20% by weight, preferably 0.1 to 20% by weight. It is 10% by weight, more preferably 0.5 to 5% by weight, and particularly preferably 1 to 3% by weight.

In the present invention, if necessary, another monomer copolymerizable with the above monomer (hereinafter referred to as “other monomer”) can be used together with the above monomer.

The other monomer is not particularly limited as long as it can be copolymerized with the above-mentioned monomer, and examples thereof include aromatic vinyl, ethylenically unsaturated nitrile, acrylamide-based monomer, and other olefin-based monomer. And so on.

Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene and the like. Examples of the ethylenically unsaturated nitrile include acrylonitrile and methacrylonitrile. Examples of the acrylamide monomer include acrylamide and methacrylamide. Examples of other olefinic monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, and the like.

The above-mentioned other monomers are used alone or in combination of two or more, and the proportion in the acrylic rubber is usually 0 to 30% by weight, preferably 0 to 20% by weight, more preferably 0 to 20% by weight. 15 parts by weight, most preferably 0 to 10 parts by weight.

<Acrylic rubber>
The acrylic rubber constituting the acrylic rubber sheet of the present invention contains a (meth)acrylic acid ester as a main component, and its content may be appropriately selected depending on the intended use of the intended product, but is usually 50. It is at least wt%, preferably at least 70 wt%, more preferably at least 80 wt%.

The acrylic rubber constituting the acrylic rubber sheet of the present invention contains a (meth)acrylic acid ester as a main component, and preferably has a reactive group.

The reactive group is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably at least one functional group selected from the group consisting of a carboxyl group, an epoxy group and a halogen group, more preferably a carboxyl group. When it is a base, the properties of the crosslinked product of the acrylic rubber sheet can be highly improved, which is preferable. Further, the reactive group is preferably an ion-reactive group such as a carboxyl group or an epoxy group because the water resistance can be particularly improved. As the acrylic rubber having such a reactive group, a reactive group may be added to the acrylic rubber by a post-reaction, but it is preferable that a reactive monomer (reactive group-containing monomer) is copolymerized. preferable.

The content of the reactive group may be appropriately selected according to the purpose of use, but it is usually 0.001 or more, preferably 0.001 to 5% by weight, more preferably 0 in terms of the weight ratio of the reactive group itself. 0.01 to 3% by weight, particularly preferably 0.05 to 1% by weight, and most preferably 0.1 to 0.5% by weight, in the range of workability, strength characteristics, compression set resistance characteristics, oil resistance, Properties such as cold resistance and water resistance are highly balanced and suitable.

Specific examples of the acrylic rubber constituting the acrylic rubber sheet of the present invention include at least one (meth)acrylic acid ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester, It is composed of a reactive monomer and other monomer used as necessary, and the ratio of each is from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester as the main components. The bond unit derived from at least one (meth)acrylic acid ester selected is usually 50% by weight or more, preferably 70 to 99.9% by weight, more preferably 80 to 99.5% by weight, particularly preferably 87 to It is in the range of 99% by weight, and the binding unit derived from the reactive monomer is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, and particularly It is preferably in the range of 1 to 3% by weight, and the bonding unit derived from other monomers is usually 0 to 30% by weight, preferably 0 to 20% by weight, more preferably 0 to 15% by weight, particularly preferably It is in the range of 0 to 10% by weight. By setting the weight ratio of each of the above monomers constituting the acrylic rubber within this range, the object of the present invention can be highly achieved, and water resistance and compression set resistance when the acrylic rubber sheet is a crosslinked product. Is significantly improved, which is preferable.

The acrylic rubber constituting the acrylic rubber sheet of the present invention has a weight average molecular weight (Mw) of 100,000 to 5,000,000, preferably 500,000 to 4,000 in terms of absolute molecular weight measured by GPC-MALS. ,000,000, more preferably 700,000 to 3,000,000, and most preferably 1,000,000 to 2,500,000, the workability and strength characteristics of the acrylic rubber sheet are highly balanced. Therefore, it is preferable.

The ratio (Mz/Mw) between the z-average molecular weight (Mz) and the weight-average molecular weight (Mw) of the acrylic rubber that constitutes the acrylic rubber sheet of the present invention is not particularly limited, but it is measured by GPC-MALS. In terms of absolute molecular weight distribution focusing on the high molecular weight region, it is usually 1.3 or more, preferably 1.4 to 5, more preferably 1.5 to 2, when the workability and strength of the acrylic rubber sheet are high. It is preferable because the properties are highly balanced and changes in physical properties (especially strength properties) during storage can be relaxed.

In the acrylic rubber sheet of the present invention, the glass transition temperature (Tg) of the acrylic rubber constituting the sheet is not particularly limited, but is usually 20°C or lower, preferably 10°C or lower, more preferably 0°C or lower. The lower limit value of the glass transition temperature (Tg) of the acrylic rubber is not particularly limited, but is usually −80° C. or higher, preferably −60° C. or higher, more preferably −40° C. or higher. When the glass transition temperature is at least the above lower limit, the oil resistance and heat resistance will be more excellent, and when it is at most the above upper limit, the cold resistance and workability will be more excellent.

<Acrylic rubber sheet>
The acrylic rubber sheet of the present invention is characterized in that it is made of the above acrylic rubber and that the ash content and the ash component satisfy specific conditions. That is, the ash content of the acrylic rubber sheet of the present invention is. It is 0.8% by weight or less, preferably 0.6% by weight or less, more preferably 0.4% by weight or less, particularly preferably 0.3% by weight or less, and most preferably 0.25% by weight or less. When the ash content is within this range, the acrylic rubber sheet has excellent storage stability and water resistance.

The lower limit of the ash content of the acrylic rubber sheet of the present invention is not particularly limited, but is, for example, 0.0001% by weight or more, preferably 0.0005% by weight or more, more preferably 0.001% by weight or more. , Particularly preferably 0.005% by weight or more, and most preferably 0.01% by weight or more, the metal adhesion of the acrylic rubber sheet is reduced, and the operability and handleability are excellent, which is preferable. Is.

The ash content which highly balances the storage stability, water resistance and metal adhesion of the acrylic rubber sheet of the present invention is usually 0.0001 to 0.8% by weight, preferably 0.0005 to 0.6% by weight, The range is more preferably 0.001 to 0.4% by weight, particularly preferably 0.05 to 0.3% by weight, and most preferably 0.01 to 0.25% by weight.

The total amount of magnesium and phosphorus in the ash content of the acrylic rubber sheet of the present invention is 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight, as a ratio to the total ash content. %, the storage stability and water resistance are highly excellent and suitable.

The ratio ([Mg]/[P]) of magnesium to phosphorus in the ash content of the acrylic rubber sheet of the present invention is 0.4 to 2.5, preferably 0.4 to 1.3, more preferably a weight ratio. Is preferably 0.4 to 1, particularly preferably 0.45 to 0.75, and most preferably 0.5 to 0.7, because the storage stability and water resistance are highly excellent. ..

The water content of the acrylic rubber sheet of the present invention 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 vulcanization property Is optimized and the properties such as heat resistance and water resistance are highly excellent and suitable.

The specific gravity of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 0.7 to 1.5, preferably 0.8 to 1.4, more preferably 0.9 to 1.3, and particularly preferably. When it is in the range of 0.95 to 1.25, most preferably 1.0 to 1.2, the storage stability is highly excellent and suitable.

The amount of gel of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 50% by weight or less, more preferably 30% by weight or less, particularly preferably 10% by weight or less, most preferably methyl insoluble ketone content. When it is 5% by weight or less, the workability is highly improved, which is preferable.

The pH of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 6 or less, preferably 2 to 6, more preferably 2.5 to 5.5, and particularly preferably 3 to 5. Storage stability is highly improved, which is preferable.

The complex viscosity ([η] 60°C) at 60°C of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 15,000 Pa·s or less, preferably 2,000 to 10,000 Pa·s. , More preferably 2,500 to 7,000 Pa·s, and most preferably 2,500 to 5,500 Pa·s, which is excellent in workability, oil resistance, and shape retention and is suitable.

The complex viscosity ([η] 100° C.) of the acrylic rubber sheet of the present invention at 100° C. is not particularly limited, but is usually 1,500 to 6,000 Pa·s, preferably 2,000 to 5, 000 Pa·s, more preferably 2,500 to 4,000 Pa·s, and most preferably 2,500 to 3,500 Pa·s, which is excellent in workability, oil resistance, and shape retention, and is suitable. ..

Ratio ([η]100°C/[η]60°C) of complex viscosity at 100°C ([η]100°C) and complex viscosity at 60°C ([η]60°C) of the acrylic rubber sheet of the present invention Is not particularly limited, but is usually 0.5 or more, preferably 0.6 to 0.98, more preferably 0.7 to 0.96, particularly preferably 0.8 to 0.95, and most preferably 0. When it is 83 to 0.93, workability, oil resistance, and shape retention are highly balanced, which is preferable.

The Mooney viscosity (ML1+4,100° C.) of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 10 to 150, preferably 20 to 100, more preferably 25 to 70 when processed. The properties and strength characteristics are highly balanced and suitable.

The thickness of the acrylic rubber sheet of the present invention is appropriately selected according to the purpose of use, but is usually 1 to 45 mm, preferably 2 to 40 mm, more preferably 3 to 25 mm, and particularly preferably 3 to 20 mm. In particular, the thickness in the case of manufacturing an inexpensive acrylic rubber sheet with markedly improved productivity is usually 1 to 15 mm, preferably 2 to 10 mm, and more preferably 3 to 8 mm.

The width of the acrylic rubber sheet of the present invention is appropriately selected according to the purpose of use, but is usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm, particularly excellent in handleability. It is suitable.

The length of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm, particularly excellent in handleability and suitable. Is.

<Method of manufacturing acrylic rubber sheet>
The method for producing the acrylic rubber sheet is not particularly limited, but for example, a monomer component containing a (meth)acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid emulsifier, and then polymerized. An emulsion polymerization step of obtaining an emulsion polymerization solution by emulsion polymerization in the presence of a catalyst, a coagulation step of producing a hydrous crumb by contacting the obtained emulsion polymerization solution with a magnesium salt aqueous solution as a coagulant, and a hydrous crumb produced. The washing step of washing and the washed water-containing crumb were dehydrated to a water content of 1 to 40% by weight in a dehydration barrel using a dehydration barrel having a dehydration slit, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip. It can be easily manufactured by including a dehydration/drying/molding step of subsequently drying the sheet-shaped dry rubber from a die by drying it to less than 1% by weight in a drying barrel.

Hereinafter, preferred embodiments of the above respective steps will be described in detail.

(Emulsion polymerization process)
In the emulsion polymerization step in the method for producing an acrylic rubber sheet of the present invention, a monomer component containing a (meth)acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid emulsifier, and emulsified in the presence of a polymerization catalyst. It is characterized by being polymerized to obtain an emulsion polymerization liquid.

Monomer component The monomer components used in the emulsion polymerization step are the same as those exemplified as the monomer component of the acrylic rubber, and the suitable components are also the same as those described as the preferable range.

Emulsifier In the emulsion polymerization step, a divalent phosphoric acid emulsifier is preferably used as the emulsifier. The type thereof is not particularly limited as long as it is a divalent phosphoric acid type and is usually used in an emulsion polymerization reaction. For example, alkyloxypolyoxyalkylene phosphate or its salt or alkylphenyloxypolyoxyalkylene. A phosphoric acid ester or its salt can be used conveniently.

Examples of the alkyloxypolyoxyalkylene phosphate or a salt thereof include alkyloxypolyoxyethylene phosphate or a salt thereof, alkyloxypolyoxypropylene phosphate or a salt thereof, and the like. Polyoxyethylene phosphate or its salt is preferred.

Specific examples of the alkyloxypolyoxyethylene phosphate ester or salt thereof preferably used include octyloxydioxyethylene phosphate ester, octyloxytrioxyethylene phosphate ester, octyloxytetraoxyethylene phosphate ester, and decyl. Oxytetraoxyethylene phosphate, dodecyloxytetraoxyethylene phosphate, tridecyloxytetraoxyethylene phosphate, tetradecyloxytetraoxyethylene phosphate, hexadecyloxytetraoxyethylene phosphate, octadecyloxytetra Oxyethylene phosphoric acid ester, octyloxypentaoxyethylene phosphoric acid ester, decyloxypentaoxyethylene phosphoric acid ester, dodecyloxypentaoxyethylene phosphoric acid ester, tridecyloxypentaoxyethylene phosphoric acid ester, tetradecyloxypentaoxyethylene phosphoric acid ester Acid ester, hexadecyloxypentaoxyethylene phosphoric acid ester, octadecyloxypentaoxyethylene phosphoric acid ester, octyloxyhexaoxyethylene phosphoric acid ester, decyloxyhexaoxyethylene phosphoric acid ester, dodecyloxyhexaoxyethylene phosphoric acid ester, tri Decyloxyhexaoxyethylene phosphate, tetradecyloxyhexaoxyethylene phosphate, hexadecyloxyhexaoxyethylene phosphate, octadecyloxyhexaoxyethylene phosphate, octyloxyoctaoxyethylene phosphate, decyloxyocta Oxyethylene phosphate, dodecyloxyoctaoxyethylene phosphate, tridecyloxyoctaoxyethylene phosphate, tetradecyloxyoctaoxyethylene phosphate, hexadecyloxyoctaoxyethylene phosphate, octadecyloxyoctaoxyethylene Examples thereof include phosphoric acid esters and the like, and metal salts thereof, etc., preferably those metal salts, more preferably their alkali metal salts, most preferably their sodium salts.

Specific examples of the alkyloxypolyoxypropylene phosphate ester or a salt thereof include, for example, octyloxydioxypropylene phosphate ester, octyloxytrioxypropylene phosphate ester, octyloxytetraoxypropylene phosphate ester, decyloxytetraphosphate. Oxypropylene phosphate, dodecyloxytetraoxypropylene phosphate, tridecyloxytetraoxypropylene phosphate, tetradecyloxytetraoxypropylene phosphate, hexadecyloxytetraoxypropylene phosphate, octadecyloxytetraoxypropylene Phosphate ester, octyloxypentaoxypropylene phosphate ester, decyloxypentaoxypropylene phosphate ester, dodecyloxypentaoxypropylene phosphate ester, tridecyloxypentaoxypropylene phosphate ester, tetradecyloxypentaoxypropylene phosphate ester Ester, hexadecyloxypentaoxypropylene phosphate, octadecyloxypentaoxypropylene phosphate, octyloxyhexaoxypropylene phosphate, decyloxyhexaoxypropylene phosphate, dodecyloxyhexaoxypropylene phosphate, tridecyl Oxyhexaoxypropylene phosphate ester, tetradecyloxyhexaoxypropylene phosphate ester, hexadecyloxyhexaoxypropylene phosphate ester, octadecyloxyhexaoxypropylene phosphate ester, octyloxyoctaoxypropylene phosphate ester, decyloxyoctaoxy Propylene phosphate ester, dodecyloxyoctaoxypropylene phosphate ester, tridecyloxyoctaoxyethylene phosphate ester, tetradecyloxyoctaoxypropylene phosphate ester, hexadecyloxyoctaoxypropylene phosphate ester, octadecyloxyoctaoxypropylenephosphate ester Examples thereof include acid esters and the like, and metal salts thereof, etc., preferably those metal salts, more preferably their alkali metal salts, most preferably their sodium salts.

Specific examples of the alkylphenyloxypolyoxyalkylene phosphate ester or salt thereof include alkylphenyloxypolyoxyethylene phosphate ester or salt thereof, alkylphenyloxypolyoxypropylene phosphate ester or salt thereof, and the like. Among them, alkylphenyloxypolyoxyethylene phosphate ester salts are preferable.

Specific examples of suitable alkylphenyloxy polyoxyethylene phosphoric acid esters or salts thereof include methyloxyoxytetraoxyethylene phosphoric acid ester, ethylphenyloxytetraoxyethylene phosphoric acid ester, butylphenyloxytetraoxyethylene phosphoric acid ester, Hexylphenyloxytetraoxyethylene phosphate, nonylphenyloxytetraoxyethylene phosphate, dodecylphenyloxytetraoxyethylene phosphate, octadecyloxytetraoxyethylene phosphate, methylphenyloxypentaoxyethylene phosphate, ethyl Phenyloxypentaoxyethylene phosphate, butylphenyloxypentaoxyethylene phosphate, hexylphenyloxypentaoxyethylene phosphate, nonylphenyloxypentaoxyethylene phosphate, dodecylphenyloxypentaoxyethylene phosphate, Methylphenyloxyhexaoxyethylene phosphate, ethylphenyloxyhexaoxyethylene phosphate, butylphenyloxyhexaoxyethylene phosphate, hexylphenyloxyhexaoxyethylene phosphate, nonylphenyloxyhexaoxyethylene phosphate, Dodecylphenyloxyhexaoxyethylene phosphate, methylphenyloxyhexaoxyethylene phosphate, ethylphenyloxyoctaoxyethylene phosphate, butylphenyloxyoctaoxyethylene phosphate, hexylphenyloxyoctaoxyethylene phosphate, Nonylphenyloxyoctaoxyethylene phosphate, dodecylphenyloxyoctaoxyethylene phosphate, and the like, and metal salts thereof, preferably those metal salts, more preferably their alkali metal salts, most preferably those. Is the sodium salt of.

Examples of the alkylphenyloxypolyoxypropylene phosphate ester or a salt thereof include methylphenyloxytetraoxypropylene phosphate ester, ethylphenyloxytetraoxypropylene phosphate ester, butylphenyloxytetraoxypropylene phosphate ester, and hexylphenyl ester. Oxytetraoxypropylene phosphate ester, nonylphenyloxytetraoxypropylene phosphate ester, dodecylphenyloxytetraoxypropylene phosphate ester, methylphenyloxypentaoxypropylene phosphate ester, ethylphenyloxypentaoxypropylene phosphate ester, butylphenyl Oxypentaoxypropylene phosphate, hexylphenyloxypentaoxypropylene phosphate, nonylphenyloxypentaoxypropylene phosphate, dodecylphenyloxypentaoxypropylene phosphate, methylphenyloxyhexaoxypropylene phosphate, ethyl Phenyloxyhexaoxypropylene phosphate, butylphenyloxyhexaoxypropylene phosphate, hexylphenyloxyhexaoxypropylene phosphate, nonylphenyloxyhexaoxypropylene phosphate, dodecylphenyloxyhexaoxypropylene phosphate, methyl Phenyloxyoctaoxypropylene phosphate ester, ethylphenyloxyoctaoxypropylene phosphate ester, butylphenyloxyoctaoxypropylene phosphate ester, hexylphenyloxyoctaoxyethylene phosphate ester, nonylphenyloxyoctaoxypropylene phosphate ester, dodecyl Examples thereof include phenyloxyoctaoxypropylene phosphate ester, and metal salts thereof. Among these, the above-mentioned metal salts are preferable, more preferably their alkali metal salts, and most preferably their sodium salts.

These divalent phosphoric acid emulsifiers can be used alone or in combination of two or more, and the amount used is usually 0.01 to 10 parts by weight with respect to 100 parts by weight of the monomer component. , Preferably 0.1 to 5 parts by weight, more preferably 1 to 3 parts by weight.

In the present invention, other emulsifiers other than the divalent phosphoric acid emulsifier may be used in combination with the divalent phosphoric acid emulsifier, if necessary. As other emulsifiers, for example, other anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers and the like are used, preferably other anionic emulsifiers, nonionic emulsifiers, more preferably other anionic emulsifiers, particularly preferably It is a monovalent phosphoric acid emulsifier.

Examples of other anionic emulsifiers include fatty acid emulsifiers such as myristic acid, palmitic acid, oleic acid, and linolenic acid; monovalent phosphoric acid emulsifiers such as di(alkyloxypolyoxyalkylene) phosphate ester salts; dodecylbenzene. Examples thereof include alkylbenzene sulfonic acid-based emulsifiers such as sodium sulfonate; sulfuric acid-based emulsifiers such as sodium lauryl sulfate. Of these, monovalent phosphoric acid-based emulsifiers and sulfuric acid-based emulsifiers are preferable, and monovalent phosphoric acid-based emulsifiers are particularly preferable. preferable.

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

Examples of nonionic emulsifiers include polyoxyalkylene fatty acid esters such as polyoxyethylene stearic acid esters; polyoxyalkylene alkyl ethers such as polyoxyethylene dodecyl ether; polyoxyalkylene alkylphenol ethers such as polyoxyethylene nonylphenyl ether; poly Examples thereof include oxyethylene sorbitan alkyl ester, and polyoxyalkylene alkyl ether and polyoxyalkylene alkylphenol ether are preferable, and polyoxyethylene alkyl ether and polyoxyethylene alkylphenol ether are more preferable.

Other emulsifiers other than these divalent phosphoric acid emulsifiers can be used alone or in combination of two or more, and the amount used is appropriately selected within a range that does not impair the effects of the present invention.

The method of mixing the monomer component, water and the emulsifier may be a conventional method, and examples thereof include a method of stirring the monomer, the emulsifier and water using a stirrer such as a homogenizer or a disk turbine. The amount of water used is usually 1 to 1000 parts by weight, preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, particularly preferably 15 to 150 parts by weight, relative to 100 parts by weight of the monomer component. The most preferred range is 20 to 80 parts by weight.

The polymerization catalyst used is not particularly limited as long as it is one usually used in emulsion polymerization, but for example, a redox catalyst composed of a radical generator and a reducing agent can be used.

Examples of the radical generator include peroxides and azo compounds, and peroxides are preferable. An inorganic peroxide or an organic peroxide is used as the peroxide.

Examples of the inorganic peroxide include sodium persulfate, potassium persulfate, hydrogen peroxide, ammonium persulfate, and the like. Among these, potassium persulfate, hydrogen peroxide, ammonium persulfate are preferable, and potassium persulfate is particularly preferable. preferable.

The organic peroxide is not particularly limited as long as it is a known one used in emulsion polymerization. For example, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, 1-di-(t-hexylperoxy)cyclohexane, 1,1-di-(t-butylperoxy)cyclohexane, 4,4-di-(t-butylperoxy)n-butylvalerate, 2,2 -Di-(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide, 1,1,3,3-tetraethylbutyl Hydroperoxide, t-butylcumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, diisobutyryl peroxide, Di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, disuccinic acid peroxide, dibenzoyl peroxide, di(3-methylbenzoyl) peroxide, benzoyl(3-methylbenzoyl) peroxide, Diisobutyryl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutylperoxide Oxyneodecanate, t-hexylperoxypivalate, t-butylperoxyneodecanate, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5,-di (2-Ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate, t-hexylperoxy-2-ethylhexanate, t-butylperoxy-3 ,5,5-Trimethylhexanate, t-hexyl peroxyisopropyl monocarbonate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5- Di(benzoylperoxy)hexane, t-butylperoxyacetate, t-hexylperoxybenzoate, t-butylperoxybenzoate, 2,5-dimethyl-2.5-di( Examples thereof include t-butylperoxy)hexane, and among these, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide and the like are preferable.

Examples of the azo compound include azobisisoptyronitrile, 4,4′-azobis(4-cyanovaleric acid), 2,2′-azobis[2-(2-imidazolin-2-yl)propane, 2, 2'-azobis(propane-2-carbamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropanamide], 2,2'-azobis{2-[1-(2 -Hydroxyethyl)-2-imidazolin-2-yl]propane}, 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) and 2,2'-azobis{2-methyl-N- [1,1-bis(hydroxymethyl)-2-hydroxyethyl]propanamide} and the like.

These radical generators can be used alone or in combination of two or more, and the amount thereof is usually 0.0001 to 5 parts by weight, preferably 0 to 100 parts by weight of the monomer component. 0.0005 to 1 part by weight, more preferably 0.001 to 0.5 part by weight.

The reducing agent can be used without particular limitation as long as it is used in a redox catalyst for emulsion polymerization, but in the present invention, it is particularly preferable to use at least two reducing agents. As the at least two reducing agents, for example, a combination of a metal ion compound in a reduced state and another reducing agent is suitable.

The metal ion compound in the reduced state is not particularly limited, but examples thereof include ferrous sulfate, sodium hexamethylenediaminetetraacetate, cuprous naphthenate, and the like, and among these, ferrous sulfate is preferable. These metal ion compounds in the reduced state can be used alone or in combination of two or more, and the amount thereof used is usually 0.000001-0. The amount is 01 parts by weight, preferably 0.00001 to 0.001 parts by weight, and more preferably 0.00005 to 0.0005 parts by weight.

The reducing agent other than the metal ion compound in the reduced state is not particularly limited, and examples thereof include ascorbic acid, sodium ascorbate, and ascorbic acid such as potassium ascorbate or a salt thereof; erythorbic acid, sodium erysorbate, and erysorbin. Erythorbic acid or its salt such as potassium acid salt; Sulfinic acid salt such as sodium hydroxymethanesulfinate; Sodium sulfite, potassium sulfite, sodium hydrogen sulfite, sodium aldehyde sulfite, potassium sulfite sulfite; Sodium pyrosulfite, potassium pyrosulfite Pyrosulfites such as sodium bisulfite, potassium bisulfite; thiosulfates such as sodium thiosulfate, potassium thiosulfate; Phosphorous acid or a salt thereof; pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, sodium hydrogen pyrophosphite, pyropyrophosphite such as potassium hydrogen pyrophosphite or a salt thereof; sodium formaldehyde sulfoxylate and the like. Among these, 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 can be used alone or in combination of two or more, and the amount thereof is usually 0.001 to 100 parts by weight with respect to 100 parts by weight of the monomer component. The amount is 1 part by weight, preferably 0.005 to 0.5 part by weight, more preferably 0.01 to 0.3 part by weight.

The ratio of the combination of the metal ion compound in the reduced state and the other reducing agent is not particularly limited, but may be [metal ion compound in the reduced state]/[reducing agent other than the metal ion compound in the reduced state]. When the weight ratio is usually 1/999999 to 5/5, preferably 1/99999 to 1/9, more preferably 1/9999 to 1/99, and particularly preferably 1/999 to 5/995, This is preferable because productivity can be improved to a high degree.

A preferred combination of the metal ion compound in a 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, and more preferably with ferrous sulfate. A combination of ascorbate and/or sodium formaldehyde sulfoxylate, most preferably a combination of ferrous sulfate and ascorbate. The amount of ferrous sulfate used at this time is usually 0.000001 to 0.01 parts by weight, preferably 0.00001 to 0.001 parts by weight, and more preferably 0, relative to 100 parts by weight of the monomer component. In the range of 0.0005 to 0.0005 parts by weight, the amount of ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate used is usually 0.001 to 1 parts by weight, preferably 100 parts by weight of the monomer component. Is 0.005 to 0.5 part by weight, more preferably 0.01 to 0.3 part by weight.

The amount of water used in the emulsion polymerization reaction may be only that used at the time of emulsifying the monomer component, but is usually 1 to 1000 parts by weight, preferably 5 to 100 parts by weight of the monomer component used for the polymerization. It is in the range of 500 parts by weight, more preferably 10 to 300 parts by weight, particularly preferably 15 to 150 parts by weight, and most preferably 20 to 80 parts by weight.

The emulsion polymerization reaction may be carried out in a conventional manner, and may be a batch system, a semi-batch system or a continuous system. The polymerization temperature and the polymerization time are not particularly limited and can be appropriately selected depending on the type of the polymerization initiator used and the like. The polymerization temperature is usually 0 to 100°C, preferably 5 to 80°C, more preferably 10 to 50°C, and the polymerization time is usually 0.5 to 100 hours, preferably 1 to 10 hours.

The polymerization conversion rate of the emulsion polymerization reaction is not particularly limited, but is usually 80% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more, which is excellent in strength characteristics of the acrylic rubber sheet produced. Moreover, it has no monomer odor and is suitable. A polymerization terminator may be used to terminate the polymerization.

(Coagulation process)
The coagulation step in the method for producing an acrylic rubber sheet of the present invention is characterized in that the emulsion polymerization liquid obtained in the emulsion polymerization step is brought into contact with a magnesium salt aqueous solution as a coagulant to produce hydrous crumbs.

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

The magnesium salt used as a coagulant is not particularly limited, and examples thereof include inorganic magnesium salts such as magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium formate, and organic magnesium salts such as magnesium acetate. Among them, inorganic Agnesium salt is preferable, and magnesium sulfate is particularly preferable.

These magnesium salts may be used alone or in combination of two or more, and the amount thereof is usually 0.01 to 100 parts by weight, preferably 0.1 part by weight per 100 parts by weight of the monomer component. It is in the range of 1 to 50 parts by weight, more preferably 1 to 30 parts by weight. When the magnesium salt is in this range, the compression set resistance and the water resistance when the acrylic rubber is crosslinked can be highly improved while the acrylic rubber is sufficiently coagulated, which is preferable. In addition, in the present invention, a coagulant other than the above-mentioned magnesium salt may be used together within a range that does not impair the effects of the present invention.

When the magnesium salt concentration of the aqueous magnesium salt solution to be used is usually in the range of 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, the produced water-containing crumbs are It is preferable because the particle size can be uniformly focused in a specific region.

The temperature of the aqueous magnesium salt solution to be used is not particularly limited, but is preferably 40° C. or higher, preferably 40 to 90° C., and more preferably 50 to 80° C. because a uniform hydrous crumb is produced. ..

The method of contacting the emulsion polymerization liquid and the magnesium salt aqueous solution is not particularly limited, but for example, a method of adding the emulsion polymerization liquid to the stirred magnesium salt aqueous solution, a magnesium salt in the stirred emulsion polymerization liquid. Although any of the methods of adding an aqueous solution may be used, the method of adding an emulsion polymerization solution to a stirred magnesium salt aqueous solution can improve the shape and crumb diameter of the hydrous crumbs to be produced, and can be used as an emulsifier or coagulant in the subsequent step. It is preferable because the cleaning efficiency of the agent can be remarkably improved.

The stirring speed (rotation speed) of the stirred magnesium salt aqueous solution, that is, the rotating speed of the stirring blade of the stirring device is not particularly limited, but the water content generated when the magnesium salt-containing aqueous solution is vigorously stirred is generated. In order to make the crumb particle size small and uniform, a rotation speed of 100 rpm or higher is usually suitable, preferably 200 to 1,000 rpm, more preferably 300 to 900 rpm, particularly preferably 350 to 850, most preferably 400 to 800 rpm. The range is. If the stirring rate (rotation speed) of the aqueous magnesium salt solution is too low and the flow rate is slow, one with a large crumb particle size and one with a small crumb particle size will be produced, and if it is too high, it will be difficult to control the coagulation reaction. , Neither is preferable.

The peripheral speed of the magnesium salt aqueous solution being stirred is the speed of the outer circumference of the stirring blade of the stirrer, and is not particularly limited, but as described above, the water-containing crumb particle size generated by vigorous stirring. Is preferably 0.5 m/s or more, preferably 1 m/s or more, more preferably 1.5 m/s or more, particularly preferably 2 m/s or more and most preferably 2.5 m/s. s or more. On the other hand, the upper limit of the peripheral speed is not particularly limited, but is usually 50 m/s or less, preferably 30 m/s or less, more preferably 25 m/s or less, and most preferably 20 m/s or less. This is preferable because the coagulation reaction can be easily controlled.

In the present invention, the number of revolutions of the magnesium salt-containing aqueous system in the coagulation step (the number of agitation) is the number of revolutions of the magnesium salt-containing aqueous solution with the rotational speed of the stirring blade provided in the coagulation tank containing the coagulant, The peripheral speed of the magnesium salt-containing aqueous system is defined as the peripheral speed of the aqueous solution by the rotational linear velocity of the outer circumference of the stirring blade.

(Washing process)
The washing step in the method for producing an acrylic rubber sheet of the present invention is a step of washing the hydrous crumb produced in the coagulation step.

The washing method is not particularly limited and may be an ordinary method. For example, the generated water-containing crumb can be mixed with a large amount of water.

The amount of water used in the washing step is not particularly limited, but the amount per washing with water is usually 50 parts by weight or more, preferably 50 to 15,000 parts by weight, preferably 100 parts by weight, based on 100 monomer components. When the amount is 100 to 10,000 parts by weight, more preferably 150 to 5,000 parts by weight, the amount of ash in the acrylic rubber can be effectively reduced, which is preferable.

The temperature of the water used in the washing step is not particularly limited, but when hot water is used, the washing efficiency is improved, which is preferable. The temperature of the warm water is not particularly limited, but it is usually 40° C. or higher, preferably 40 to 100° C., more preferably 50 to 90° C., most preferably 60 to 80° C., because the cleaning efficiency can be remarkably increased, which is preferable. Is. By setting the temperature of the washing water to the above lower limit or more, the emulsifier and the coagulant are released from the water-containing crumb, and the washing efficiency is further improved.

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 washings (washing with water) is not particularly limited and is usually 1 to 10 times, preferably a plurality of times, more preferably 2 to 3 times. From the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber, it is desirable that the number of times of washing with water is large, but the shape of the hydrous crumb and the hydrous crumb diameter should be adjusted to a specific range. And/or the cleaning temperature can be remarkably reduced by setting the cleaning temperature in the above range.

(Dehydration/drying/molding process)
In the dehydration/drying/molding step in the method for producing an acrylic rubber sheet of the present invention, the washed water-containing crumb is a screw including a dehydration barrel having a dehydration slit, a drying barrel for drying under reduced pressure, and a die at the tip. It is characterized in that the sheet-shaped dry rubber is extruded by performing dehydration, drying and molding using a die extruder.

In the present invention, the water-containing crumb supplied to the screw type extruder is preferably one in which free water is removed (drained) after washing.

Draining Step In the method for producing an acrylic rubber sheet of the present invention, after the washing step and before the dehydration/drying step, it is possible to provide a draining step of separating free water from the water-containing crumb after washing with a drainer to improve the dehydration efficiency. It is suitable for raising.

As the drainer, known ones can be used without particular limitation, and examples thereof include a wire mesh, a screen, an electric sifter, and the like, and the wire mesh and the screen are preferable. The opening of the drainer is not particularly limited, but when the range is usually 0.01 to 5 mm, preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm, the loss of hydrous crumbs is small. In addition, it is suitable because draining can be performed efficiently.

The water content of the water-containing crumb after draining, that is, the water content of the water-containing crumb to be added to the dehydration/drying/molding step is not particularly limited, but is usually 50 to 80% by weight, preferably 50 to 70% by weight, more preferably It is in the range of 50 to 60% by weight.

The temperature of the water-containing crumb after draining, that is, the temperature of the water-containing crumb to be added to the dehydration/drying/molding step is not particularly limited, but is usually 40°C or higher, preferably 40 to 95°C, more preferably 50 to 90°C. Particularly preferred is a rubber having a high specific heat of 1.5 to 2.5 KJ/kg·K, like the acrylic rubber of the present invention, in the range of 55 to 85° C., and most preferably 60 to 80° C. The water-containing crumb of (2) can be dehydrated and dried efficiently by using a screw type extruder, which is preferable.

Dehydration of hydrous crumb (dehydration barrel)
In the present invention, dehydration of the hydrous crumb is performed in the dehydration barrel portion having the dehydration slit provided in the screw type extruder. The opening of the dehydration slit may be appropriately selected depending on the use conditions, but is usually 0.01 to 5 mm, preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.6 mm. At a certain time, there is little loss of hydrous crumb, and dehydration of the water-free crumb can be efficiently dehydrated, which is preferable. The number of dehydrating barrels in this screw type extruder is not particularly limited, but when the number is usually plural, preferably 2 to 10 and more preferably 3 to 6, the tacky acrylic rubber is efficiently dehydrated. The above is preferable.

The water discharged from the dehydration slit in the dehydration of the hydrous crumb may be in a liquid state (drainage) or a vapor state (exhaust vapor). In the present invention, wastewater is defined as dehydration, and waste steam is defined as pre-drying for distinction.

When using a screw type extruder equipped with a plurality of dehydration barrels, it is preferable to combine drainage (dehydration) and exhaust steam (preliminary drying) so that the adhesive acrylic rubber can be efficiently dehydrated and the water content reduced. Is. In a screw type extruder having three or more dehydration barrels, the selection of each dehydration barrel to be a drainage type dehydration barrel or an exhaust steam type dehydration barrel may be appropriately made according to the purpose of use, but is usually manufactured. It is appropriate to increase the number of drainage barrels to reduce the ash content in acrylic rubber, and to increase the amount of waste steam barrels to reduce the water content.

The set temperature of the dehydration barrel is appropriately selected depending on the type of acrylic rubber, the ash content, the water content, the operating conditions, etc., but is usually 60 to 150°C, preferably 70 to 140°C, more preferably 80 to 130°C. Range. The set temperature of the dehydrating barrel for dehydrating in the drainage state is usually 60°C to 120°C, preferably 70 to 110°C, more preferably 80 to 100°C, and the setting temperature of the dehydrating barrel for performing preliminary drying in the exhaust steam state is , Usually 100 to 150° C., preferably 105 to 140° C., and more preferably 110 to 130° C.

The water content after dehydration by squeezing water from the water-containing crumb, that is, the water content after passing through the drainage type barrel is not particularly limited, but the water content is usually 1 to 45% by weight, preferably 1 to 40% by weight, more preferably Dehydration to 5 to 35% by weight, particularly preferably 10 to 35% by weight, is suitable because the ash removal efficiency and the productivity are highly balanced.
It is suitable because it can be made into a dry crumb containing almost no water (water content less than 1% by weight) in a drying barrel under reduced pressure in the next step.

Dehydration of highly sticky acrylic rubber can be hardly done because the acrylic rubber adheres to the dehydration slit when using a centrifuge or the like (the water content is reduced to only about 45 to 55% by weight). In the present invention, it is preferable to use a screw type extruder equipped with a dehydrating barrel having a dehydrating slit and forcibly squeezed by a screw, since the water content can be effectively reduced to a lower content.

When the screw type extruder is equipped with a drainage type dehydration barrel and an exhaust steam type dehydration barrel, the dehydration state of the water-containing crumb is such that the water content after dehydration in the drainage type dehydration barrel portion is usually 5 to 45% by weight, preferably 10 40% by weight, more preferably 15 to 35% by weight, and the water content after preliminary drying in the exhaust steam type dehydration barrel is usually 1 to 30% by weight, preferably 3 to 20% by weight, more preferably 5 to 15%. % By weight.

Drying of hydrous crumb (drying in the drying barrel)
In the present invention, the dehydrated hydrous crumb is dried in a drying barrel section under reduced pressure provided on the downstream side of the dehydrating barrel section in the screw type extruder. The degree of decompression of the drying barrel may be appropriately selected, but is usually 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa, since the hydrous crumb can be efficiently dried, which is preferable.

The set temperature of the drying barrel may be appropriately selected, but when the temperature is usually 100 to 250° C., preferably 110 to 200° C., more preferably 120 to 180° C., there is no burning or deterioration of the acrylic rubber. It is preferable because it can be efficiently dried and the gel amount of the acrylic rubber sheet can be reduced.

The number of drying barrels in the screw type extruder is not particularly limited, but is usually plural, preferably 2 to 10, and more preferably 3 to 8. When a plurality of drying barrels are provided, the degree of pressure reduction may be similar to that of all the drying barrels, or may be changed. When multiple drying barrels are provided, the set temperature may be similar to that of all the drying barrels or may be changed, but the temperature of the discharge section (closer to the dehydration barrel) than the temperature of the discharge section (closer to the die). It is preferable to increase the temperature of (1) because the drying efficiency can be increased.

The water content of the acrylic rubber after drying is usually less than 1% by weight, preferably 0.8% by weight or less, and more preferably 0.6% by weight or less. In the present invention, particularly when the water content of the acrylic rubber reaches this value (a state in which most of the water is removed) and melt-extruded in the screw type extruder, the gel amount of the acrylic rubber is reduced, and bubbles entrapped are reduced. It is important for reducing and increasing the specific gravity.

Acrylic rubber shape (die part)
The acrylic rubber dehydrated and dried by the screw parts of the dehydration barrel and the drying barrel is sent to a screwless straightening die part provided near the tip of the screw type extruder. A breaker plate or a wire net may or may not be provided between the screw part and the die part.

Acrylic rubber extruded from the die part of the screw type extruder is suitable because it is possible to obtain a dry rubber with less air entrapment and small specific gravity and excellent storage stability by extruding the die shape into a substantially rectangular shape and extruding into a sheet shape. is there.

The resin pressure in the die part is not particularly limited, but when the range is usually 0.1 to 10 MPa, preferably 0.5 to 5 MPa, and more preferably 1 to 3 MPa, entrainment of air is small (specific gravity is large). It is also preferable because it is excellent in productivity.

Operating Conditions of Screw Type Extruder The screw length (L) of the screw type extruder used may be appropriately selected according to the purpose of use, but is usually 3,000 to 15,000 mm, preferably 4,000 to 10,000 mm, more preferably 4,500. The range is up to 8000 mm.

The screw diameter (D) of the screw type extruder used may be appropriately selected according to the purpose of use, but is usually 50 to 250 mm, preferably 100 to 200 mm, and more preferably 120 to 160 mm.

The ratio (L/D) of the screw length (L) and the screw diameter (D) of the screw type extruder used is not particularly limited, but is usually 10 to 100, preferably 20 to 80, When it is in the range of 30 to 60, the water content is preferably less than 1% by weight without lowering the molecular weight of the dried rubber or causing burning, which is preferable.

The rotation speed (N) of the screw type extruder used may be appropriately selected according to various conditions, but is usually 10 to 1000 rpm, preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120. When it is up to 300 rpm, the water content and gel content of the acrylic rubber can be efficiently reduced, which is preferable.

The extrusion rate (Q) of the screw type extruder used is not particularly limited, but usually 100 to 1,500 kg/hr is suitable, preferably 300 to 1,200 kg/hr, more preferably 400 to 1, 000 kg/hr, most preferably 500 to 800 kg/hr.

The ratio (Q/N) of the extrusion rate (Q) and the number of revolutions (N) of the screw type extruder used is not particularly limited, but is usually 1 to 20, preferably 2 to 10, and more preferably Is preferably in the range of 3 to 8, and particularly preferably in the range of 4 to 6, because the tacky acrylic rubber can be efficiently dehydrated, dried and molded.

The dry rubber extruded from the sheet-shaped dry rubber screw type extruder is in the form of a sheet, and at this time, the specific gravity can be increased without entrainment of air, and the storage stability of the resulting acrylic rubber sheet is highly improved, which is preferable. is there. The sheet-shaped dry rubber extruded from the screw type extruder is cooled, and then cut into a predetermined size as required to obtain an acrylic rubber sheet.

The thickness of the sheet-shaped dry rubber extruded from the screw type extruder is not particularly limited, but is usually 1 to 40 mm, preferably 2 to 35 mm, more preferably 3 to 30 mm, and most preferably 5 to 25 mm. It is preferable because it has excellent workability and productivity. In particular, since the thermal conductivity of the sheet-shaped dry rubber is as low as 0.15 to 0.35 W/mK, the thickness of the sheet-shaped dry rubber is usually 1 to 30 mm when the cooling efficiency is increased and the productivity is remarkably improved. The range is preferably 2 to 25 mm, more preferably 3 to 15 mm, and particularly preferably 4 to 12.

The width of the sheet-shaped dry rubber extruded from the screw type extruder is appropriately selected according to the purpose of use, but the width is usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm.

The temperature of the sheet-shaped dry rubber extruded from the screw type extruder is not particularly limited, but is usually 100° C. or higher, preferably 100 to 200° C., more preferably 110 to 180° C., and particularly preferably 120 to 160. It is in the range of °C.

The water content of the sheet-shaped dry rubber extruded from the screw type extruder is less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less.

The complex viscosity ([η] 100° C.) at 100° C. of the sheet-shaped dry rubber extruded from the screw type extruder is not particularly limited, but is usually 1,500 to 6,000 Pa·s, preferably 2 5,000 to 5,000 Pa·s, more preferably 2,500 to 4,000 Pa·s, and most preferably 2,500 to 3,500 Pa·s, the extrudability as a sheet and the sheet The shape is highly balanced and suitable. When the value of the complex viscosity at 100° C. ([η] 100° C.) is not less than the lower limit, the extrudability can be made more excellent, and when the value is not more than the upper limit, the shape of the sheet-shaped dry rubber becomes undesired. Fracture can be suppressed.

The method for cooling the sheet-shaped dry rubber is not particularly limited and may be left at room temperature, but since the sheet-shaped dry rubber has a very small thermal conductivity of 0.1 to 0.4, it may be blown or cooled. In order to improve productivity, forced cooling such as an air cooling method in the above, a water spraying method in which water is sprayed, and a dipping method in which the material is immersed in water is preferable, and an air cooling method under blowing or cooling is particularly preferable.

In the air-cooling method of the sheet-shaped dry rubber, for example, the sheet-shaped dry rubber can be extruded from a screw type extruder onto a conveyor such as a belt conveyor and conveyed while being cooled by cold air to be cooled. The temperature of the cold air is not particularly limited, but is usually 0 to 30°C, preferably 5 to 25°C, more preferably 10 to 20°C. The length to be cooled is not particularly limited, but is usually 5 to 500 m, preferably 10 to 200 m, more preferably 20 to 100 m. The cooling rate of the sheet-shaped dry rubber is not particularly limited, but it is particularly easy to cut when it is usually 50° C./hr or higher, more preferably 100° C./hr or higher, more preferably 150° C./hr or higher. And is preferable.

The temperature at which the sheet-shaped dry rubber is cut is not particularly limited, but when the temperature is usually 60°C or lower, preferably 55°C or lower, more preferably 50°C or lower, the cuttability and the productivity are highly balanced. Is preferred.

The complex viscosity at 60° C. ([η] 60° C.) of the sheet-like dry rubber that becomes the acrylic rubber sheet according to the present invention is not particularly limited, but is usually 15,000 Pa·s or less, preferably 2,000. ˜10,000 Pa·s, more preferably 2,500 to 7,000 Pa·s, and most preferably 2,500 to 5,500 Pa·s, it is possible to cut continuously without entraining air. It is suitable.

Further, the ratio ([η]100°C/[η]60°C) of the complex viscosity at 100°C ([η]100°C) and the complex viscosity at 60°C ([η]60°C) of the dry rubber sheet. ) Is not particularly limited, but is usually 0.5 or more, preferably 0.6 to 0.98, more preferably 0.75 to 0.95, particularly preferably 0.8 to 0.94, and most preferably When it is in the range of 0.83 to 0.93, air entrainment is low, and cutting and productivity are highly balanced, which is preferable.

The cut length of the sheet-shaped dry rubber for forming the acrylic rubber sheet of the present invention is not particularly limited and may be appropriately selected depending on the purpose of use of the rubber sheet, but is usually 100 to 800 mm, preferably 200 to It is in the range of 500 mm, more preferably 250 to 450 mm.

The thus obtained acrylic rubber sheet of the present invention is superior in operability and storage stability to crumb-shaped acrylic rubber, and can be used as it is or after being laminated as described below to be veiled.

<Acrylic rubber veil>
The acrylic rubber veil of the present invention is characterized in that the acrylic rubber sheets are laminated and integrated. The size of the veil produced from the acrylic rubber sheet of the present invention is not particularly limited, but the width is usually 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm, and the length. Is usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm, and the height is usually more than 50 mm and 500 mm or less, preferably 100 to 300 mm, more preferably 150 to 250 mm.

Water content of acrylic rubber veil, ash content, total amount and ratio of magnesium and phosphorus in ash, specific gravity, gel amount, pH, complex viscosity at 60°C ([η] 60°C), complex viscosity at 100°C ( [Η] 100°C), ratio of complex viscosity at 100°C ([η] 100°C) to complex viscosity at 60°C ([η] 60°C) ([η] 100°C/[η] 60°C) , And the Mooney viscosity (ML1+4,100° C.) characteristic values are the same as the respective characteristic values of the acrylic rubber sheet.

The method for producing the acrylic rubber veil of the present invention is not particularly limited, but for example, by cooling the sheet-shaped dry rubber extruded from the screw type extruder, cutting, and laminating and integrating a plurality of sheets. Manufactured.

The lamination temperature of the sheet-shaped dry rubber is not particularly limited, but is usually 30° C. or higher, preferably 35° C. or higher, and more preferably 40° C. or higher, because air entrapped during lamination can be escaped, which is preferable. The number of laminated layers is appropriately selected according to the size or weight of the acrylic rubber veil.

The acrylic rubber veil thus obtained is superior in operability and storage stability to crumb-shaped acrylic rubber. Use the acrylic rubber veil as it is or cut it into a kneader such as Banbury or roll after cutting the required amount. You can

<Rubber mixture>
The rubber mixture of the present invention is characterized by mixing the acrylic rubber sheet or the acrylic rubber veil with a filler and a crosslinking agent.

The filler constituting the rubber mixture is not particularly limited, but examples thereof include a reinforcing filler and a non-reinforcing filler, and preferably a reinforcing filler.

Examples of the reinforcing filler include carbon black such as furnace black, acetylene black, thermal black, channel black and graphite; silica such as wet silica, dry silica and colloidal silica; and the like. 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. be able to.

These fillers can be used alone or in combination of two or more, and the compounding amount thereof is appropriately selected within a range that does not impair the effects of the present invention, and is 100 parts by weight of the acrylic rubber sheet or acrylic rubber veil. On the other hand, it is usually in the range of 1 to 200 parts by weight, preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight.

The cross-linking agent that constitutes the rubber mixture may be appropriately selected depending on the type and application of the reactive group contained in the acrylic rubber that constitutes the acrylic rubber sheet or the acrylic rubber veil, but the acrylic rubber sheet or the acrylic rubber There is no particular limitation as long as it can crosslink the veil, and examples thereof include polyvalent amine compounds such as diamine compounds and their carbonates; sulfur compounds; sulfur donors; triazine thiol compounds; polyvalent epoxy compounds; ammonium organic carboxylates. Conventionally known crosslinking agents such as salts; organic peroxides; polyvalent carboxylic acids; quaternary onium salts; imidazole compounds; isocyanuric acid compounds; organic peroxides; triazine compounds can be used. Among these, polyvalent amine compounds, carboxylic acid ammonium salts, dithiocarbamic acid metal salts and triazine thiol compounds are preferable, and hexamethylenediamine carbamate, 2,2′-bis[4-(4-aminophenoxy)phenyl]propane, benzoin Particularly preferred are ammonium acid and 2,4,6-trimercapto-1,3,5-triazine.

When the acrylic rubber sheet or acrylic rubber veil used is composed of a carboxyl group-containing acrylic rubber, it is preferable to use a polyvalent amine compound and its carbonate as a crosslinking agent. Examples of the polyvalent amine compound include aliphatic polyvalent amine compounds such as hexamethylenediamine, hexamethylenediamine carbamate, and N,N′-dicinnamylidene-1,6-hexanediamine; 4,4′-methylenedianiline, p -Phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(m-phenylenediisopropylidene)dianiline, 4,4'-(p-phenylenediamine) Isopropylidene)dianiline, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminobenzanilide, 4,4'-bis(4-aminophenoxy)biphenyl, m-xylyl Aromatic polyamine compounds such as diamine, p-xylylenediamine and 1,3,5-benzenetriamine; and the like. Among these, hexamethylenediamine carbamate and 2,2′-bis[4-(4-aminophenoxy)phenyl]propane are preferable.

When the acrylic rubber sheet or acrylic rubber veil used is composed of an epoxy group-containing acrylic rubber, an aliphatic polyvalent amine compound such as hexamethylenediamine or hexamethylenediamine carbamate, and a carbonate thereof as a cross-linking agent; Aromatic polyvalent amine compounds such as 4′-methylenedianiline; ammonium benzoate, ammonium adipate carboxylic acid ammonium salts thereof; metal salts of dithiocarbamic acid such as zinc dimethyldithiocarbamate; polyvalent carboxylic acids such as tetradecanedioic acid; Quaternary onium salts such as cetyltrimethylammonium bromide; imidazole compounds such as 2-methylimidazole; isocyanuric acid compounds such as ammonium isocyanurate; and the like can be used, and among these, carboxylate ammonium salts and dithiocarbamic acid metal salts are preferable. Ammonium benzoate is more preferred.

When the acrylic rubber sheet or acrylic rubber veil used is composed of a halogen atom-containing acrylic rubber, it is preferable to use sulfur, a sulfur donor, or a triazine thiol compound as the crosslinking agent. Examples of the sulfur donor include dipentamethylene thiuram hexasulfide, triethyl thiuram disulfide and the like. Examples of the triazine compound include 6-trimercapto-s-triazine, 2-anilino-4,6-dithiol-s-triazine, 1-dibutylamino-3,5-dimercaptotriazine and 2-dibutylamino-4, 6-dithiol-s-triazine, 1-phenylamino-3,5-dimercaptotriazine, 2,4,6-trimercapto-1,3,5-triazine, 1-hexylamino-3,5-dimercaptotriazine And the like. Among these, 2,4,6-trimercapto-1,3,5-triazine is preferable.

These cross-linking agents can be used alone or in combination of two or more, and the compounding amount thereof is usually 0.001 to 20 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the acrylic rubber sheet or the acrylic rubber veil. Is 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight. By setting the amount of the cross-linking agent to be in this range, the rubber elasticity can be made sufficient, and the mechanical strength of the cross-linked rubber can be made excellent, which is preferable.

The rubber mixture of the present invention can use other rubber components other than the acrylic rubber sheet or the acrylic rubber veil, if necessary. Other rubber components used as needed are not particularly limited, and examples thereof include natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicone rubber, fluororubber, and olefin. Examples thereof include a system elastomer, a styrene system elastomer, a vinyl chloride system elastomer, a polyester system elastomer, a polyamide system elastomer, a polyurethane system elastomer, and a polysiloxane system elastomer.
These other rubbers may be used alone or in combination of two or more. The shape of these other rubbers may be a veil, a sheet, a powder, or the like. The amount of these other rubber components used is appropriately selected within a range that does not impair the effects of the present invention.

An antioxidant can be blended in the rubber mixture of the present invention if necessary. The type of anti-aging agent is not particularly limited, but it is 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, butylhydroxyanisole, 2,6-di-t-butyl. -Α-dimethylamino-p-cresol, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, styrenated phenol, 2,2'-methylene-bis(6-α-methyl) -Benzyl-p-cresol), 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 2,4- Bis[(octylthio)methyl]-6-methylphenol, 2,2'-thiobis-(4-methyl-6-t-butylphenol), 4,4'-thiobis-(6-t-butyl-o-cresol) , 2,6-di-t-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol and other phenolic antioxidants; tris(nonylphenyl)phos Phosphite-based antioxidants such as phyto, diphenylisodecyl phosphite, tetraphenyldipropylene glycol/diphosphite; Sulfur ester-based antioxidants such as dilauryl thiodipropionate; Phenyl-α-naphthylamine, phenyl-β-naphthylamine , P-(p-toluenesulfonylamide)-diphenylamine, 4,4′-(α,α-dimethylbenzyl)diphenylamine, N,N-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p- Amine-based antioxidants such as phenylenediamine and butyraldehyde-aniline condensates; Imidazole-based antioxidants such as 2-mercaptobenzimidazole; 6-Ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline And quinoline anti-aging agents; hydroquinone anti-aging agents such as 2,5-di-(t-amyl)hydroquinone; and the like. Of these, amine-based antioxidants are particularly preferable.

These antioxidants can be used alone or in combination of two or more, and the compounding amount thereof is usually 0.01 to 15 parts by weight with respect to 100 parts by weight of the acrylic rubber sheet or the acrylic rubber veil. , Preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight.

The rubber mixture of the present invention contains the above-mentioned acrylic rubber sheet or acrylic rubber veil of the present invention, a filler, a cross-linking agent, and, if necessary, other rubber components and an antioxidant. The rubber mixture of the present invention may further contain other additives, if necessary, commonly used in the art, for example, a crosslinking aid, a crosslinking accelerator, a crosslinking retarder, a silane coupling agent, a plasticizer, a processing aid. Agents, lubricants, pigments, colorants, antistatic agents, foaming agents and the like can be optionally mixed. These other compounding agents can be used alone or in combination of two or more, and the compounding amount thereof is appropriately selected within a range that does not impair the effects of the present invention.

As the method for producing the rubber mixture of the present invention, the acrylic rubber sheet or the acrylic rubber veil of the present invention is mixed with a filler, a cross-linking agent, and other rubber components that can be optionally contained, an antioxidant and other compounding agents. For example, any of the conventional means used in the rubber processing field, such as an open roll, a Banbury mixer, and various kneaders can be used for mixing. The mixing procedure of each component is not particularly limited, but, for example, after sufficiently mixing components that are difficult to react or decompose with heat, a crosslinking agent, which is a component that easily reacts or decomposes with heat, is not reacted or decomposed. Mixing for a short time at a temperature that does not occur is preferred.

<Crosslinked rubber>
The crosslinked rubber of the present invention is obtained by crosslinking the above rubber mixture.

The rubber cross-linked product of the present invention is obtained by molding the rubber mixture of the present invention using a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor or a roll, and crosslinking reaction by heating. And fixing the shape as a rubber cross-linked product. In this case, the molding may be performed in advance and then crosslinked, or the molding and the crosslinking may be performed simultaneously. The molding temperature is usually 10 to 200°C, preferably 25 to 150°C. The crosslinking temperature is usually 100 to 250° C., preferably 130 to 220° C., more preferably 150 to 200° C., and the crosslinking time is usually 0.1 minutes to 10 hours, preferably 1 minute to 5 hours. As a heating method, a method used for crosslinking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

The rubber cross-linked product of the present invention may be further heated for secondary cross-linking depending on the shape and size of the rubber cross-linked product. The secondary crosslinking varies depending on the heating method, the crosslinking temperature, the shape, etc., but is preferably 1 to 48 hours. The heating method and heating temperature may be appropriately selected.

The rubber cross-linked product of the present invention is a sealing material such as an O-ring, packing, diaphragm, oil seal, shaft seal, bearing sheath, mechanical seal, well head seal, electric/electronic device seal, air compression device seal, and the like. A unit cell provided with a rocker cover gasket mounted on the connecting portion between the cylinder block and the cylinder head, an oil pan gasket mounted on the connecting portion between the oil pan and the cylinder head or the transmission case, a positive electrode, an electrolyte plate and a negative electrode. Various gaskets such as gaskets for fuel cell separators and hard disk drive top covers mounted between a pair of sandwiched housings; cushioning materials, vibration damping materials, wire coating materials, industrial belts, tubes and hoses, sheets , And the like.

The rubber cross-linked product of the present invention is also used as an extrusion molding product and mold cross-linked product used for automobiles, for example, a fuel oil around a fuel tank such as a fuel hose, a filler neck hose, a vent hose, a paper hose and an oil hose. It is preferably used for various hoses such as air hoses such as system hoses, turbo air hoses, and mission control hoses, radiator hoses, heater hoses, brake hoses, air conditioner hoses.

<Apparatus configuration used for manufacturing acrylic rubber sheet>
Next, a device configuration used for manufacturing the acrylic rubber sheet according to the 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 configuration used for manufacturing an acrylic rubber sheet according to an embodiment of the present invention. For manufacturing the acrylic rubber sheet according to the present invention, for example, the acrylic rubber manufacturing system 1 shown in FIG. 1 can be used.

The acrylic rubber production system 1 shown in FIG. 1 includes an emulsion polymerization reactor (not shown), a coagulation device 3, a cleaning device 4, a drainer 43, a screw type extruder 5, a cooling device 6, and a baling device 7. ..

The emulsion polymerization reactor is configured to perform the process related to the emulsion polymerization process described above. Although not shown in FIG. 1, this emulsion polymerization reactor has, for example, a polymerization reaction tank, a temperature controller for controlling the reaction temperature, a motor, and a stirring device equipped with a stirring blade. In an emulsion polymerization reactor, water and a divalent phosphoric acid emulsifier are mixed with a monomer component for forming an acrylic rubber, and the mixture is emulsified while appropriately stirring with a stirrer, and emulsion polymerization is performed in the presence of a polymerization catalyst. By doing so, an emulsion polymerization liquid can be obtained. The emulsion polymerization reactor may be a batch type, a semi-batch type or a continuous type, and may be a tank type reactor or a tube type reactor.

The coagulation device 3 shown in FIG. 1 is configured to perform the above-mentioned coagulation process. As schematically illustrated in FIG. 1, the solidification device 3 includes, for example, a stirring tank 30, a heating unit 31 that heats the inside of the stirring tank 30, a temperature control unit (not shown) that controls the temperature inside the stirring tank 30, The stirring device 34 includes a motor 32 and a stirring blade 33, and a drive control unit (not shown) that controls the rotation speed and rotation speed of the stirring blade 33. In the coagulation device 3, a hydrous crumb can be produced by bringing the emulsion polymerization liquid obtained in the emulsion polymerization reactor into contact with the coagulation liquid to coagulate it.

In the coagulation device 3, for example, the contact between the emulsion polymerization liquid and the magnesium salt aqueous solution employs a method of adding the emulsion polymerization liquid to the stirring magnesium salt aqueous solution. That is, the stirring tank 30 of the coagulation device 3 is filled with a magnesium salt aqueous solution, and the emulsion polymerization liquid is added to and brought into contact with the magnesium salt aqueous solution to solidify the emulsion polymerization liquid, thereby generating a hydrous crumb.

The heating unit 31 of the coagulation device 3 is configured to heat the magnesium salt aqueous solution with which the stirring tank 30 is filled. In addition, the temperature control unit of the coagulation device 3 controls the temperature inside the stirring tank 30 by controlling the heating operation by the heating unit 31 while monitoring the temperature inside the stirring tank 30 measured by the thermometer. It is configured. The temperature of the magnesium salt aqueous solution in the stirring tank 30 is controlled by the temperature control unit to be usually 40°C or higher, preferably 40 to 90°C, more preferably 50 to 80°C.

The stirrer 34 of the coagulation device 3 is configured to stir the magnesium salt aqueous solution with which the stirring tank 30 is filled. Specifically, the stirring device 34 includes a motor 32 that produces rotational power and a stirring blade 33 that spreads in a direction perpendicular to the rotation axis of the motor 32. The stirring blade 33 can rotate the magnesium salt aqueous solution filled in the stirring tank 30 about the rotation axis by the rotation power of the motor 32 to flow the magnesium salt aqueous solution. The shape and size of the stirring blade 33, the number of installations, etc. 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 to set the rotation speed and rotation speed of the stirring blades 33 of the stirring device 34 to predetermined values. The stirring number of the magnesium salt aqueous solution is, for example, usually 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm, and particularly preferably 400 to 800 rpm. Controlled. The peripheral speed of the aqueous magnesium salt solution is usually 0.5 m/s or more, preferably 1 m/s or more, more preferably 1.5 m/s or more, particularly preferably 2 m/s or more, most preferably 2.5 m/s or more. The rotation of the stirring blade 33 is controlled by the drive control unit so that Furthermore, the upper limit of the peripheral speed of the aqueous magnesium salt solution is usually 50 m/s or less, preferably 30 m/s or less, more preferably 25 m/s or less, and most preferably 20 m/s or less by the drive control unit. The rotation of the stirring blade 33 is controlled.

The cleaning device 4 shown in FIG. 1 is configured to perform the process related to the above-described cleaning process. As schematically illustrated in FIG. 1, the cleaning device 4 includes, for example, a cleaning tank 40, a heating unit 41 that heats the inside of the cleaning tank 40, and a temperature control unit (not shown) that controls the temperature inside the cleaning tank 40. Have. In the cleaning device 4, the amount of ash in the finally obtained acrylic rubber sheet can be effectively reduced by mixing the water-containing crumb generated in the coagulation device 3 with a large amount of water for cleaning.

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

The water-containing crumb washed by the washing device 4 is supplied to the screw type extruder 5 that performs a dehydration step and a drying step. At this time, the water-containing crumb after washing is preferably supplied to the screw type extruder 5 through a drainer 43 capable of separating free water. For the drainer 43, for example, a wire mesh, a screen, an electric sifter, or the like can be used.

Moreover, when the water-containing crumb after washing is supplied to the screw type extruder 5, the temperature of the water-containing crumb is preferably 40° C. or higher, more preferably 60° C. or higher. For example, by maintaining the temperature of water used for washing in the cleaning device 4 at 60° C. or higher (for example, 70° C.), the temperature of the water-containing crumb when supplied to the screw type extruder 5 is maintained at 60° C. or higher. Alternatively, the water-containing crumb may be heated to a temperature of 40° C. or higher, preferably 60° C. or higher when being conveyed from the cleaning device 4 to the screw type extruder 5. This makes it possible to effectively perform the dehydration step and the drying step, which are the post-steps, and to significantly reduce the water content of the finally obtained dried rubber.

The screw type extruder 5 shown in FIG. 1 is configured to perform the processes related to the dehydration process and the drying process described above. In addition, although the screw type extruder 5 is illustrated in FIG. 1 as a suitable example, a centrifuge, a squeezer, or the like may be used as a dehydrator for performing the process related to the dehydration process, and the process related to the drying process is performed. A hot air dryer, a reduced pressure dryer, an expander dryer, a kneader dryer, or the like may be used as the dryer to be used.

The screw type extruder 5 is configured to mold and discharge the dried rubber obtained through the dehydration step and the drying step into a predetermined shape. Specifically, the screw-type extruder 5 has a dehydrating barrel portion 53 having a function as a dehydrator for dehydrating the water-containing crumbs washed by the cleaning device 4, and a dryer having a function as a dryer for drying the water-containing crumbs. And a barrel 59, and a die 59 having a forming function of forming a hydrous crumb on the downstream side of the screw type extruder 5.

Hereinafter, the configuration of the screw type extruder 5 will be described with reference to FIG. FIG. 2 shows a configuration of a specific example suitable as the screw type extruder 5 shown in FIG. With the screw type extruder 5, the above-described dehydration/drying step can be suitably performed.

The screw type extruder 5 shown in FIG. 2 is a twin-screw type extruder/dryer including a pair of screws (not shown) in the barrel unit 51. The screw type extruder 5 has a drive unit 50 that rotationally drives a pair of screws in the barrel unit 51. The drive unit 50 is attached to the upstream end (left end in FIG. 2) of the barrel unit 51. Further, the screw type extruder 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 drying barrel portion 54 from the upstream side to the downstream side (from the left side to the right side in FIG. 2).

The supply barrel portion 52 is configured by two supply barrels, that is, a first supply barrel 52a and a second supply barrel 52b.

Further, the dehydration barrel portion 53 is composed of three dehydration barrels, that is, a first dehydration barrel 53a, a second dehydration barrel 53b and a third dehydration barrel 53c.

Further, the drying barrel portion 54 includes eight drying barrels, that is, the first drying barrel 54a, the second drying barrel 54b, the third drying barrel 54c, the fourth drying barrel 54d, and the fifth drying barrel 54e. , A sixth drying barrel 54f, a seventh drying barrel 54g, and an eighth drying barrel 54h.

As described above, the barrel unit 51 is configured by connecting the 13 divided barrels 52a to 52b, 53a to 53c, and 54a to 54h from the upstream side to the downstream side.

Further, the screw type extruder 5 individually heats each of the barrels 52a to 52b, 53a to 53c, 54a to 54h, and determines the water-containing crumbs in each of the barrels 52a to 52b, 53a to 53c, 54a to 54h. It has a heating means (not shown) for heating to a temperature. The heating means is provided with a number corresponding to each barrel 52a-52b, 53a-53c, 54a-54h. As such a heating means, for example, a configuration in which high temperature steam is supplied from a steam supply means to a steam distribution jacket formed in each barrel 52a to 52b, 53a to 53c, 54a to 54h is adopted. It is not limited to this. Further, the screw type extruder 5 has a temperature control means (not shown) for controlling the set temperature of each heating means corresponding to each barrel 52a to 52b, 53a to 53c, 54a to 54h.

The number of supply barrels, dehydration barrels, and drying barrels constituting the barrel portions 52, 53, and 54 of the barrel unit 51 is not limited to that shown in FIG. The number can be set according to the water content of the water-containing crumb.

For example, the number of supply barrels installed in the supply barrel portion 52 is, for example, 1 to 3. Further, the number of dehydrating barrels installed in the dehydrating barrel portion 53 is preferably, for example, 2 to 10, and more preferably 3 to 6 because the water-containing crumb of the adhesive acrylic rubber can be efficiently dehydrated. Moreover, the number of the drying barrels installed in the drying barrel portion 54 is, for example, preferably 2 to 10, and more preferably 3 to 8.

The pair of screws in the barrel unit 51 are rotationally driven by a driving unit such as a motor stored in the driving unit 50. The pair of screws extend from the upstream side to the downstream side in the barrel unit 51, and by being rotationally driven, the hydrous crumbs supplied to the supply barrel portion 52 can be conveyed to the downstream side while being mixed. It is like this. The pair of screws is preferably a biaxial meshing type in which peaks and valleys are meshed with each other, which can enhance the dehydration efficiency and drying efficiency of the water-containing crumb.

Further, the pair of screws may rotate in the same direction or in different directions, but from the viewpoint of self-cleaning performance, a type in which they rotate in the same direction is preferable. The screw shape of the pair of screws is not particularly limited, and may be any shape required for each barrel portion 52, 53, 54, and is not particularly limited.

The supply barrel portion 52 is an area for supplying the water-containing crumb into the barrel unit 51. The first supply barrel 52 a of the supply barrel portion 52 has a feed port 55 for supplying the water-containing crumb into the barrel unit 51.

The dehydration barrel portion 53 is an area for separating and discharging a liquid (serum water) containing a coagulant and the like from a water-containing crumb.

The 1st-3rd dewatering barrels 53a-53c which comprise the dewatering barrel part 53 have the dewatering slits 56a, 56b, 56c which discharge|release the water|moisture content of a water-containing crumb, respectively. A plurality of dehydration slits 56a, 56b, 56c are formed in each of the dehydration barrels 53a to 53c.

The slit width of each dehydration slit 56a, 56b, 56c, that is, the opening may be appropriately selected according to the use conditions, and is usually 0.01 to 5 mm, and the loss of the hydrous crumb is small, and It is preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm, from the viewpoint of efficient dehydration.

There are two ways to remove water from the water-containing crumbs in the dehydration barrels 53a to 53c of the dehydration barrel portion 53, that is, to remove it in a liquid state from each of the dehydration slits 56a, 56b and 56c and to remove it in a vapor state. .. In the dehydration barrel portion 53 of the present embodiment, the case of removing liquid in a liquid state is defined as drainage, and the case of removing in a vapor state is defined as exhaust steam, and is distinguished.

In the dehydration barrel portion 53, it is preferable to combine drainage and exhaust steam because it is possible to efficiently reduce the water content of the adhesive acrylic rubber. In the dewatering barrel portion 53, which of the first to third dewatering barrels 53a to 53c is to be used for draining or discharging steam may be appropriately set according to the purpose of use, but is usually manufactured. When reducing the ash content in acrylic rubber, it is advisable to increase the number of dewatering barrels for draining. In that case, for example, as shown in FIG. 2, the first and second dehydrating barrels 53a and 53b on the upstream side perform drainage, and the third dehydrating barrel 53c on the downstream side performs waste steam. In addition, for example, when the dehydration barrel portion 53 has four dehydration barrels, it is conceivable that, for example, the three dehydration barrels on the upstream side perform drainage and the one dehydration barrel on the downstream side performs waste steam. On the other hand, in the case of reducing the water content, it is preferable to increase the number of dehydrating barrels for exhausting steam.

The set temperature of the dehydration barrel portion 53 is usually in the range of 60 to 150° C., preferably 70 to 140° C., and more preferably 80 to 130° C. as described in the dehydration/drying step described above, and dehydration is performed in a drained state. The setting temperature of the dehydrating barrel is usually 60 to 120° C., preferably 70 to 110° C., more preferably 80 to 100° C., and the setting temperature of the dehydrating barrel for dehydrating in the exhaust steam state is usually 100 to 150° C. , Preferably 105 to 140°C, more preferably 110 to 130°C.

The drying barrel section 54 is an area for drying the hydrous crumb after dehydration under reduced pressure. Of the first to eighth drying barrels 54a to 54h forming the drying barrel portion 54, the second drying barrel 54b, the fourth drying barrel 54d, the sixth drying barrel 54f, and the eighth drying barrel 54h are It has vent ports 58a, 58b, 58c, 58d for deaeration, respectively. A vent pipe (not shown) is connected to each of the vent ports 58a, 58b, 58c, 58d.

A vacuum pump (not shown) is connected to the end of each vent pipe, and the inside of the drying barrel portion 54 is depressurized to a predetermined pressure by the operation of these vacuum pumps. The screw type extruder 5 has pressure control means (not shown) that controls the operation of these vacuum pumps to control the degree of pressure reduction in the drying barrel portion 54.

The degree of pressure reduction in the drying barrel portion 54 may be appropriately selected, but as described above, it is usually set to 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa.

The set temperature in the drying barrel portion 54 may be appropriately selected, but as described above, it is usually set to 100 to 250°C, preferably 110 to 200°C, and more preferably 120 to 180°C.

In each of the drying barrels 54a to 54h forming the drying barrel portion 54, the set temperatures in all the drying barrels 54a to 54h may be set to approximate values or may be different, but the upstream side (dehydration barrel portion). It is preferable to set the temperature on the downstream side (die 59 side) higher than the temperature on the 53 side) because the drying efficiency is improved.

The die 59 is a mold arranged 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 drying barrel portion 54 is extruded into a shape corresponding to a predetermined nozzle shape by passing through the ejection port of the die 59. In the present invention, the shape of the acrylic rubber passing through the die 59 can be extruded into a sheet shape by making the nozzle shape of the die 59 substantially rectangular. A breaker plate or a wire net may or may not be provided between the screw and the die 59.

According to the screw type extruder 5 according to the present embodiment, the water-containing crumb of the raw material acrylic rubber is extruded into a sheet-shaped dry rubber as follows.

The water-containing crumb of acrylic rubber obtained through the cleaning step is supplied to the supply barrel portion 52 from the feed port 55. The water-containing crumb supplied to the supply barrel portion 52 is sent from the supply barrel portion 52 to the dehydration barrel portion 53 by the rotation of a pair of screws in the barrel unit 51. In the dehydration barrel portion 53, as described above, the drainage of water contained in the hydrous crumb and the exhaust steam are performed from the dehydration slits 56a, 56b, and 56c provided in the first to third dehydration barrels 53a to 53c, respectively. The hydrous crumbs are dehydrated.

The hydrous crumbs dehydrated in the dehydration barrel section 53 are sent to the drying barrel section 54 by the rotation of a pair of screws in the barrel unit 51. The water-containing crumb sent to the drying barrel portion 54 is plasticized and mixed to form a melt, which generates heat and is conveyed to the downstream side while heating. Then, the water contained in the melt of the acrylic rubber is vaporized, and the water (vapor) is discharged to the outside through vent pipes (not shown) connected to the vent ports 58a, 58b, 58c, 58d, respectively.

By passing through the drying barrel 54 as described above, the water-containing crumb is dried and becomes a melt of acrylic rubber, and the acrylic rubber is supplied to the die 59 by the rotation of a pair of screws in the barrel unit 51, and is then formed into a sheet. Is extruded from the die 59 as dry rubber.

Here, an example of operating conditions of the screw type extruder 5 according to the present embodiment will be described.

The rotation speed (N) of the pair of screws in the barrel unit 51 may be appropriately selected according to various conditions, and is usually 10 to 1000 rpm, and the water content and gel content of the acrylic rubber sheet can be efficiently reduced. From the viewpoint, it is preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

The extrusion rate (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 500 to 800 kg/hr. hr is most preferred.

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, and more preferably It is 3-8, and 4-6 is especially preferable.

The cooling device 6 shown in FIG. 1 is configured to cool the dried rubber obtained through the dehydration process using a dehydrator and the drying process using a dryer. As a cooling method by the cooling device 6, various methods including an air cooling method in which air is blown or under cooling, a water spraying method in which water is sprayed, a dipping method in which water is immersed, and the like can be adopted. The dry rubber may be cooled by leaving it at room temperature.

Hereinafter, with reference to FIG. 3, as an example of the cooling device 6, a transport-type cooling device 60 that cools the sheet-shaped dry rubber 10 formed into a sheet will be described.

FIG. 3 shows a configuration of a transport type cooling device 60 suitable as the cooling device 6 shown in FIG. The conveyance type cooling device 60 shown in FIG. 3 is configured to cool the sheet-shaped dry rubber 10 discharged from the discharge port of the die 59 of the screw type extruder 5 by an air cooling method while conveying it. By using this conveyance type cooling device 60, the sheet-shaped dry rubber discharged from the screw type extruder 5 can be suitably cooled.

The transport cooling device 60 shown in FIG. 3 is used, for example, by being directly connected to the die 59 of the screw type extruder 5 shown in FIG. 2 or by being installed in the vicinity of the die 59.

The transport cooling device 60 conveys the sheet-shaped dry rubber 10 discharged from the die 59 of the screw type extruder 5 in the direction of arrow A in FIG. And a cooling means 65 for spraying.

The conveyor 61 has rollers 62 and 63, and a conveyor belt 64 that is wound around the rollers 62 and 63 and on which the sheet-shaped dry rubber 10 is placed. The conveyor 61 is configured to continuously convey the sheet-shaped dry rubber 10 discharged from the die 59 of the screw type extruder 5 onto the conveyor belt 64 to the downstream side (right side in FIG. 3 ).

The cooling means 65 is not particularly limited, but has a configuration capable of blowing cooling air sent from a cooling air generation means (not shown) onto the surface of the sheet-shaped dry rubber 10 on the conveyor belt 64. And so on.

The length L1 of the conveyor 61 and the cooling means 65 (the length of the portion to which the cooling air can be blown) L1 of the transport cooling device 60 is not particularly limited, but is, for example, 10 to 100 m, preferably 20 to 50 m. .. Further, the conveyance speed of the sheet-shaped dry rubber 10 in the conveyance-type cooling device 60 is the length L1 of the conveyor 61 and the cooling means 65, the discharge speed of the sheet-shaped dry rubber 10 discharged from the die 59 of the screw type extruder 5, It may be appropriately adjusted according to the target cooling rate, cooling time, etc., but is, for example, 10 to 100 m/hr, and more preferably 15 to 70 m/hr.

According to the conveyance type cooling device 60 shown in FIG. 3, while the sheet-shaped dry rubber 10 discharged from the die 59 of the screw type extruder 5 is conveyed by the conveyor 61, the sheet-shaped dry rubber 10 is cooled by the cooling means 65. By blowing the cooling air, the sheet-shaped dry rubber 10 is cooled.

The transport cooling device 60 is not particularly limited to a configuration including one conveyor 61 and one cooling means 65 as shown in FIG. 3, and two or more conveyors 61 and two or more corresponding thereto. The cooling means 65 may be included. In that case, the total length of each of the two or more conveyors 61 and the cooling means 65 may be set within the above range.

The bale-forming device 7 shown in FIG. 1 is configured to process the dried rubber extruded from the screw-type extruder 5 and cooled by the cooling device 6 to produce a bale that is a block of one block. Although the weight and shape of the acrylic rubber veil manufactured by the bale forming device 7 are not particularly limited, for example, a substantially rectangular parallelepiped acrylic rubber veil is manufactured.

Further, the sheet-shaped dry rubber 10 produced by the screw type extruder 5 may be laminated to produce an acrylic rubber veil. For example, a cutting mechanism that cuts the sheet-shaped dry rubber 10 may be provided in the bale-making device 7 that is arranged on the downstream side of the transport-type cooling device 60 shown in FIG. 3. Specifically, for example, the cutting mechanism of the bale forming device 7 continuously cuts the cooled sheet-shaped dry rubber 10 at a predetermined interval and processes the cut sheet-shaped dry rubber 16 into a predetermined size. Is configured. By stacking a plurality of cut sheet-shaped dry rubbers 16 cut into a predetermined size by the cutting mechanism, an acrylic rubber veil in which the cut sheet-shaped dry rubbers 16 are stacked can be manufactured.

When producing an acrylic rubber veil in which the cut sheet-shaped dry rubber 16 is laminated, it is preferable to laminate the cut sheet-shaped dry rubber 16 at 40° C. or higher, for example. By stacking the cut sheet dry rubber 16 at 40° C. or higher, good air release is realized by further cooling and compression by its own weight.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, "part", "%" and "ratio" in each example are based on weight unless otherwise specified. Various characteristics were evaluated according to the following methods.

[Monomer composition]
Regarding the monomer composition in the acrylic rubber, the monomer constitution of each monomer unit in the acrylic rubber was confirmed by H-NMR, and the activity of the reactive group remained in the acrylic rubber and each reaction thereof. The content of the functional group was confirmed by the following test method.
The content ratio of each monomer unit in the acrylic rubber was calculated from the amount of each monomer used in the polymerization reaction and the polymerization conversion rate. Specifically, the polymerization reaction was an emulsion polymerization reaction, and the polymerization conversion rate was about 100% at which no unreacted monomer could be confirmed. It was the same as the amount used by the body.

[Reactive group content]
The content of the reactive group of the acrylic rubber was measured as the content in the acrylic rubber sheet or the acrylic rubber veil by the following method.
(1) The amount of carboxyl group was calculated by dissolving an acrylic rubber sheet or an acrylic rubber veil in acetone and performing potentiometric titration with a potassium hydroxide solution.
(2) The amount of epoxy groups was calculated by dissolving an acrylic rubber sheet or acrylic rubber veil in methyl ethyl ketone, adding a specified amount of hydrochloric acid thereto to react with epoxy groups, and titrating the amount of residual hydrochloric acid with potassium hydroxide. ..
(3) The amount of chlorine was calculated by completely burning the acrylic rubber sheet or acrylic rubber veil in a combustion flask, absorbing the generated chlorine in water, and titrating with silver nitrate.

[Amount of ash]
The ash content (%) contained in the acrylic rubber sheet or the acrylic rubber veil was measured according to JIS K6228 A method.

[Amount of ash components]
The amount of each component (ppm) in the ash content of the acrylic rubber sheet or acrylic rubber veil was measured by XRF using ZSX Primus (manufactured by Rigaku) by pressing the collected ash content onto a titration filter paper of Φ20 mm according to the difference in the above ash content measurement. did

[Molecular weight and molecular weight distribution]
Regarding the weight average molecular weight (Mw) and the molecular weight distribution ( Mz/Mw) of acrylic rubber, lithium chloride was added to dimethylformamide as a solvent at a concentration of 0.05 mol/L and 37% concentrated hydrochloric acid at a concentration of 0.01%, respectively. It is an absolute molecular weight and an absolute molecular weight distribution measured by GPC-MALS method using a solution. Specifically, a multi-angle laser light scattering photometer (MALS) and a differential refractometer (RI) are incorporated into a GPC (Gel Permeation Chromatography) device, and the light scattering intensity and the refraction of a molecular chain solution classified by the GPC device are measured. The rate difference was measured by following the elution time to sequentially calculate the molecular weight of the solute and its content rate. The measurement conditions and the measurement method by the GPC device are as follows.
Column: TSKgel α-M 2 pieces (φ7.8 mm×30 cm, manufactured by Tosoh Corporation)
Temperature: Column 40°C
Flow rate: 0.8 ml/mm
Sample preparation: 5 mg of solvent was added to 10 mg of the sample, and the mixture was gently stirred at room temperature (dissolution was visually confirmed). Then, filtration was performed using a 0.5 μm filter.
Injection volume: 0.200 ml

[Glass transition temperature (Tg)]
The glass transition temperature (Tg) of acrylic rubber was measured using a differential scanning calorimeter (DSC, product name "X-DSC7000", manufactured by Hitachi High-Tech Science Co., Ltd.).

[Amount of gel]
The gel amount (%) of the acrylic rubber sheet or the acrylic rubber veil is the amount of insoluble matter in methyl ethyl ketone, and was determined by the following method.
About 0.2 g of acrylic rubber sheet or acrylic rubber veil was weighed (Xg), immersed in 100 ml of methyl ethyl ketone and allowed to stand at room temperature for 24 hours, and then a filtrate obtained by filtering insoluble matters in methyl ethyl ketone using an 80 mesh wire net, that is, The dry solid content (Yg) obtained by evaporating and drying and solidifying the filtrate in which only the rubber component dissolved in methyl ethyl ketone was dissolved was calculated and calculated by the following formula.
Gel amount (%)=100×(X−Y)/X

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

[Water content]
The water content (%) of the acrylic rubber sheet or the acrylic rubber veil was measured according to JIS K6238-1: Oven A (volatile content measurement) method.

[PH]
The pH of the acrylic rubber sheet or acrylic rubber veil is 6 g (±0.05 g) of the acrylic rubber sheet or acrylic rubber veil dissolved in 100 g of tetrahydrofuran, and 2.0 ml of distilled water is added to confirm that the pH has been completely dissolved. It was measured with an electrode.

[Complex viscosity]
The complex viscosity η of the acrylic rubber sheet or the acrylic rubber veil was measured using a dynamic viscoelasticity measuring device “Rubber Process Analyzer RPA-2000” (manufactured by Alpha Technology Co.) with a strain of 473% and temperature dispersion at 1 Hz (40 to 40). 120° C.) was measured, and the complex viscosity η at each temperature was determined. Here, of the above-mentioned dynamic viscoelasticities, the dynamic viscoelasticity at 60° C. is defined as the complex viscosity η (60° C.), and the dynamic viscoelasticity at 100° C. is defined as the complex viscosity η (100° C.), and the ratio η The value of (100° C.)/η (60° C.) was calculated.

[Moonie viscosity (ML1+4,100℃)]
The Mooney viscosity (ML1+4,100° C.) of the acrylic rubber sheet or the acrylic rubber veil was measured according to the uncrosslinked rubber physical test method of JIS K6300.

[Evaluation of storage stability]
Regarding the storage stability of the rubber sample, the rubber sample was put into a constant temperature and humidity chamber of 45° C.×80% RH (SH-222 manufactured by ESPEC Co.), and the change rate of water content before and after the 7-day test was calculated to obtain a comparative example. Evaluation was made with an index with 2 being 100 (the smaller the index, the better the storage stability).

[Water resistance evaluation]
The water resistance of the rubber sample was determined by immersing the crosslinked product of the rubber sample in distilled water at a temperature of 85° C. for 100 hours in accordance with JIS K6258 to perform an immersion test, and calculating the volume change rate before and after immersion according to the following formula: The evaluation was performed by an index with Comparative Example 2 being 100 (the smaller the index, the more excellent the water resistance).
Volume change rate before and after immersion (%)=((volume of test piece after immersion-volume of test piece before immersion)/volume of test piece before immersion)×100

[Example 1]
In a mixing vessel equipped with a homomixer, 46 parts of pure water, 48.25 parts of ethyl acrylate as a monomer component, 50 parts of n-butyl acrylate and 1.75 parts of mono n-butyl fumarate, and octyloxy as an emulsifier. 1.8 parts of sodium salt of dioxyethylene phosphate was charged and stirred to obtain a monomer emulsion.

170 parts of pure water and 3 parts of the monomer emulsion obtained above were put into a polymerization reaction tank equipped with a thermometer and a stirrer, and cooled to 12° C. under a nitrogen stream. Then, the rest of the monomer emulsion, 0.00033 part of ferrous sulfate, 0.264 part of sodium ascorbate, and 0.22 part of potassium persulfate were continuously dropped into the polymerization reaction tank over 3 hours. .. After that, the reaction was continued while the temperature in the polymerization reaction tank was kept at 23° C., and it was confirmed that the polymerization conversion rate reached about 100%, and the polymerization reaction was performed by adding hydroquinone as a polymerization terminator. After stopping, an emulsion polymerization liquid was obtained.

Then, in a coagulation tank equipped with a thermometer and a stirrer, a 2% magnesium sulfate aqueous solution (coagulant) heated to 80° C. and vigorously stirred at a stirring blade speed of the stirrer of 600 rotations (peripheral speed 3.1 m/s) Coagulation liquid using magnesium sulfate as an agent) In 350 parts, the emulsion polymerization liquid obtained above was heated to 80° C. and continuously added to solidify the polymer, and crumbs of acrylic rubber as a solidified product. A coagulated slurry containing water and water was obtained. Water was discharged from the solidified layer while filtering the crumb from the obtained slurry to obtain a hydrous crumb.

194 parts of hot water (70°C) was added to the coagulation tank in which the filtered hydrous crumb remained, and the mixture was stirred for 15 minutes to wash the hydrous crumb, and then water was discharged, and 194 parts of hot water (70°C) was again discharged. Was added and the mixture was stirred for 15 minutes to wash the hydrous crumb (the total number of washings was 2). The washed water-containing crumb (crumb temperature 60° C.) was supplied to a screw type extruder, dehydrated, dried and molded to extrude a sheet-shaped dry rubber having a width of 300 mm and a thickness of 10 mm. Then, the sheet-shaped dry rubber was cooled at a cooling temperature of 200° C./hr by using a conveyance type cooling device directly connected to the screw type extruder.

In addition, the screw type extruder used in this Example 1 has one feed barrel, three dehydrating barrels (first to third dehydrating barrels), and five drying barrels (first to fifth drying barrels). It is configured. The first dewatering barrel drains water, and the second and third dewatering barrels drain water. The operating conditions of the screw type extruder were as follows.

Water content-Water content of hydrous crumb after draining in the first dehydration barrel: 30%
-Water content of hydrous crumb after exhaust steam in the third dehydration barrel: 10%
Rubber temperature-Temperature of hydrous crumb supplied to supply barrel: 65℃
-Temperature of rubber discharged from screw type extruder: 140°C
Set temperature of each barrel:
・First dehydration barrel: 100°C
・Second dehydration barrel: 120℃
・Third dehydration barrel: 120℃
First drying barrel: 120°C
・Second drying barrel: 130°C
・Third drying barrel: 140℃
・Fourth drying barrel: 160°C
・Fifth drying barrel: 180°C
Operating conditions:
・Screw diameter (D): 132 mm
・Screw length (L): 4620 mm
・L/D: 35
・Screw speed: 135 rpm
・Rubber extrusion rate from die: 700 kg/hr
・Resin pressure in die: 2MPa

The sheet-shaped dry rubber extruded from the screw type extruder was cooled to 50° C. and cut with a cutter to obtain an acrylic rubber sheet (A). Reactive group content, ash content, ash component content, specific gravity, gel content, pH, glass transition temperature (Tg), water content, molecular weight, molecular weight distribution, complex viscosity of the obtained acrylic rubber sheet (A), and The Mooney viscosity (ML, 1+4, 100° C.) was measured and is shown in Table 2. The rate of change in water content of the acrylic rubber sheet (A) before and after the storage stability test was determined, and the results are shown in Table 2.

Then, while the temperature of the acrylic rubber sheet (A) does not fall below 40° C., a plurality of cut acrylic rubber sheets (A) are laminated so as to be 20 parts (20 kg) and the acrylic rubber veil (A) is laminated. Got Reactive group content, ash content, ash component content, specific gravity, gel content, pH, glass transition temperature (Tg), water content, molecular weight, molecular weight distribution, complex viscosity, Mooney of the obtained acrylic rubber veil (A) The viscosity and (ML, 1+4,100° C.) were measured.

Next, 100 parts of the acrylic rubber sheet (A) and the compounding agent A of “formulation 1” shown in Table 1 were put into a Banbury mixer and mixed at 50° C. for 5 minutes (first-stage mixing). Further, each of the mixtures obtained by the first-stage mixing was transferred to a roll at 50° C., compounding agent B of “formulation 1” was compounded and mixed (second-stage mixing) to obtain a rubber mixture.

The rubber mixture thus obtained is placed in a mold having a length of 15 cm, a width of 15 cm, and a depth of 0.2 cm, and primary cross-linking is performed by pressing at 180° C. for 10 minutes while applying a pressure of 10 MPa. The product was further heated in a gear type oven at 180° C. for 2 hours for secondary cross-linking to obtain a sheet-shaped rubber cross-linked product. Then, a water resistance test was conducted by cutting out a 3 cm×2 cm×0.2 cm test piece from the obtained sheet-shaped rubber cross-linked product, and the results are shown in Table 2.

[Example 2]
The monomer component was 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 emulsifier was nonylphenylhexaoxyethylene phosphate sodium salt. The procedure was performed in the same manner as in Example 1 except that the acrylic rubber sheet (B) and the acrylic rubber veil (B) were obtained, and each property (however, the compounding agent was changed to "compounding 2") was evaluated. The results of the acrylic rubber sheet (B) are shown in Table 2.

[Example 3]
The monomer component was 42.2 parts of ethyl acrylate, 35 parts of n-butyl acrylate, 20 parts of methoxyethyl acrylate, 1.5 parts of acrylonitrile and 1.3 parts of vinyl chloroacetate, and the emulsifier was tridecyloxyhexaoxy. The same procedure as in Example 1 was carried out except that ethylene phosphate sodium salt was used to obtain an acrylic rubber sheet (C) and an acrylic rubber veil (C), and each property (however, the compounding agent was changed to "compounding 3"). evaluated. The results of the acrylic rubber sheet (C) are shown in Table 2.

[Example 4]
The temperature of the first dehydration barrel is changed to 90°C and the temperature of the second dehydration barrel is changed to 100°C so that the drainage is performed in the first and second dehydration barrels, and after the drainage in the second dehydration barrel. An acrylic rubber sheet (D) and an acrylic rubber veil (D) were obtained in the same manner as in Example 1 except that the water content of the water-containing crumb of (2) was changed to 20%, and each property was evaluated. The results of the acrylic rubber sheet (D) are shown in Table 2.

[Example 5]
The monomer component was 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 nonylphenyloxyhexa. Acrylic rubber sheet (E) and acrylic rubber veil (E) were produced in the same manner as in Example 4 except that the sodium salt of oxyethylene phosphate ester was used, and each property (however, the compounding agent was changed to "compounding 4"). ) Was evaluated. The results of the acrylic rubber sheet (E) are shown in Table 2.

[Example 6]
The monomer component was 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, and the emulsifier was tridecyloxyhexaoxyethylene phosphate. An acrylic rubber sheet (F) and an acrylic rubber veil (F) were produced in the same manner as in Example 5 except that the sodium ester salt was used, and each property was evaluated. The results of the acrylic rubber sheet (F) are shown in Table 2.

[Comparative Example 1]
The emulsion polymerization liquid obtained by emulsion polymerization was stirred in the same manner as in Example 3 (100 rpm, peripheral speed 0.5 m/s), and a coagulation reaction was performed by adding 0.7% magnesium sulfate aqueous solution at 80° C. To generate water-containing crumbs, wash the water-containing crumbs with 194 parts of warm water (70° C.) for 15 minutes with stirring, repeat the same operation, and then dry with a hot air dryer at 160° C. 0.4% by weight of crumb-shaped acrylic rubber (G) was obtained, each property was evaluated in the same manner as in Example 3, and the results are shown in Table 2.

[Comparative Example 2]
The emulsifier was changed to 0.709 parts of lauryl sulfate sodium salt and 1.82 parts of polyoxyethylene dodecyl ether (molecular weight 1500), the coagulation liquid was changed to 0.7% sodium sulfate aqueous solution, and the coagulation reaction was changed as to the washing method. To 100 parts of the subsequent water-containing crumb, 194 parts of industrial water was added, and the mixture was stirred at 25° C. for 5 minutes in the coagulation tank. Then, the water-containing crumb that drains water from the coagulation tank was washed 4 times, and then the pH of 3 was added. After adding 194 parts of sulfuric acid aqueous solution and stirring at 25° C. for 5 minutes, drain water from the coagulation tank and perform acid cleaning once, then add 194 parts of pure water and perform pure water cleaning once. Except for changing it, the same procedure as in Comparative Example 1 was performed to obtain a crumb-shaped acrylic rubber (H), and each property was evaluated. The results are shown in Table 2.

From Table 2, the ash content is 0.8 wt% or less, the ratio of phosphorus and magnesium in the ash is 30 wt% or more with respect to the total ash content, and the weight ratio [Mg/P] of magnesium and phosphorus is It can be seen that the acrylic rubber sheets (A) to (F) of the present invention having a density of 0.4 to 2.5 have remarkably excellent storage stability and water resistance (Examples 1 to 6 and Comparative Examples 1 to 1). (Comparison with 3).

From Table 2, the ash content is more than that of the crumb-like acrylic rubber (H) coagulated with a monovalent sodium salt using a sulfuric acid-based emulsifier and washed and dried, using a divalent phosphoric acid-based emulsifier. It can be seen that the amount of crumb-like acrylic rubber (G) coagulated with salt, washed and dried is overwhelmingly large (comparison between Comparative Examples 1 and 2).

However, by specifying the concentration of the coagulant in the coagulation step, the method of addition, the number of revolutions and the peripheral speed of the coagulation liquid, and dehydrating and squeezing out the components that become ash along with water from the hydrous crumb, the acrylic rubber sheet (A) It can be seen that the amount of ash in (F) was reduced (comparison between Examples 1 to 6 and Comparative Example 1). Furthermore,. The ash content of the acrylic rubber sheets (A) to (F) is reduced to about 1/2 to 1/3 of the ash content of the crumb-shaped acrylic rubber (H), but the storage stability is 1/5. It can be seen that both properties are overwhelmingly improved, that is, ˜1/10 and water resistance is 1/10 to 1/50. This is because the ratio between the amount of phosphorus and the amount of magnesium in the ash is large, and the ratio of magnesium to phosphorus (Mg/P) is in a specific range, giving an overwhelming storage stability and water resistance improving effect. ..

From Table 2, the reactive group content, ash content, ash component content, specific gravity, gel content, pH, glass transition temperature (Tg), water content, weight average molecular weight (Mw ), z average molecular weight (Mz) Acrylic rubber sheet (A) having a ratio (Mz/Mw) with a weight average molecular weight (Mw), a complex viscosity at 100° C. and 60° C. and its viscosity ratio, and a Mooney viscosity (ML1+4,100° C.) in a specific region. It can be seen that (F) is overwhelmingly excellent in storage stability and water resistance (Examples 1 to 6).

1 Acrylic rubber manufacturing system 3 Coagulation device 4 Cleaning device 5 Screw type extruder 6 Cooling device 7 Baling device

Claims (22)

It is composed of acrylic rubber whose main component is (meth)acrylic acid ester and has a weight average molecular weight (Mw) of 100,000 to 5,000,000, an ash content of 0.8% by weight or less, and magnesium and phosphorus in the ash. Is 30% by weight or more based on the total ash content, and the ratio of magnesium to phosphorus ([Mg]/[P]) is 0.4 to 2.5 by weight. Rubber sheet. The acrylic rubber contains at least one (meth)acrylic acid ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester, a reactive monomer, and if necessary, The acrylic rubber sheet according to claim 1, which is formed of another polymerizable monomer. The acrylic rubber sheet according to claim 1 or 2, which has a complex viscosity ([η] 60°C) at 60°C of 15,000 Pa·s or less. When the ratio ([η]100°C/[η]60°C) of the complex viscosity at 100°C ([η]100°C) and the complex viscosity at 60°C ([η]60°C) is 0.5 or more, The acrylic rubber sheet according to any one of claims 1 to 3. The acrylic rubber sheet according to any one of claims 1 to 4, having a specific gravity of 0.7 to 1.5. The acrylic rubber sheet according to any one of claims 1 to 5, which has a gel amount of 50% by weight or less. The acrylic rubber sheet according to claim 1, having a pH of 6 or less. The acrylic rubber sheet according to claim 1, which has a glass transition temperature (Tg) of 20° C. or lower. Mooney viscosity (ML1+4,100 degreeC) is the range of 10-150, The acrylic rubber sheet of any one of Claims 1-8. An emulsion polymerization step in which a monomer component containing a (meth)acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid emulsifier to carry out emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid;
A coagulation step of producing a hydrous crumb by contacting the obtained emulsion polymerization liquid with an aqueous solution of a magnesium salt as a coagulant,
A washing step of washing the generated water-containing crumb,
The washed water-containing crumb was dehydrated with a dehydration barrel having a dehydration slit, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip to a water content of 1 to 40 wt. A dehydration/drying/molding process in which a sheet-shaped dry rubber is extruded from a die by drying to less than wt%,
A method for producing an acrylic rubber sheet containing: The method for producing an acrylic rubber sheet according to claim 10, wherein the emulsion polymerization liquid and the magnesium salt aqueous solution are brought into contact with each other by adding the emulsion polymerization liquid to the stirred magnesium salt aqueous solution. The method for producing an acrylic rubber sheet according to claim 11, wherein the stirring speed of the magnesium salt aqueous solution is 100 rpm or more. The method for producing an acrylic rubber sheet according to claim 11 or 12, wherein a peripheral speed of the stirred magnesium salt aqueous solution is 0.5 m/s or more. The method for producing an acrylic rubber sheet according to any one of claims 10 to 13, wherein the water-containing crumb is washed with warm water. The method for producing an acrylic rubber sheet according to any one of claims 10 to 14, wherein the number of revolutions (N) of the screw type extruder is in the range of 10 to 1000 rpm. The method for producing an acrylic rubber sheet according to any one of claims 10 to 15, wherein an extrusion rate (Q) of the screw type extruder is 100 to 1,500 kg/hr. The method for producing an acrylic rubber sheet according to any one of claims 10 to 16, wherein the temperature of the drying barrel of the screw type extruder is in the range of 100 to 250°C. The method for producing an acrylic rubber sheet according to any one of claims 10 to 17, wherein the degree of vacuum in the drying barrel of the screw type extruder is in the range of 1 to 50 kPa. The method for producing an acrylic rubber sheet according to any one of claims 10 to 18, wherein the resin pressure of the die part of the screw type extruder is in the range of 0.1 to 10 MPa. An acrylic rubber veil formed by laminating the acrylic rubber sheets according to any one of claims 1 to 9. A rubber mixture obtained by mixing the acrylic rubber sheet according to any one of claims 1 to 9 or the acrylic rubber veil according to claim 20 with a reinforcing agent and a crosslinking agent. A rubber cross-linked product obtained by cross-linking the rubber mixture according to claim 21.