JP2021017546A - Acrylic rubber sheet excellent in storage stability and water resistance - Google Patents

Abstract

To provide an acrylic rubber sheet and a method for producing the same that is excellent in storage stability and water resistance.SOLUTION: The acrylic rubber sheet comprising an acrylic rubber having a (meth)acrylic ester as the main component and having the weight average molecular weight (Mw) in a specific range and in which the ash content is 0.8 wt.% or less and the total amount of magnesium and phosphorous in the ash is 30 wt.% or more, and the ratio of magnesium and phosphorous, ([Mg]/[P]), in weight ratio, is in the range of 0.4 to 2.5, is excellent in storage stability and water resistance.SELECTED DRAWING: None

Description

The present invention relates to an acrylic rubber sheet and its manufacturing method, an acrylic rubber bale, a rubber mixture, and a rubber crosslinked product. More specifically, an acrylic rubber sheet having excellent storage stability and water resistance and a manufacturing method thereof, the acrylic rubber sheet. The present invention relates to a laminated acrylic rubber bale, a rubber mixture obtained by mixing the acrylic rubber sheet and the acrylic rubber bale, and a rubber crosslinked product obtained by cross-linking the acrylic rubber sheet.

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

Such acrylic rubber is usually obtained by emulsion-polymerizing a monomer component constituting acrylic rubber, bringing the obtained emulsion polymerization solution into contact with a coagulant, drying the obtained hydrous crumb, and then drying the crumb made of dried rubber. It is commercialized in the form of a sheet, sheet or veil.

Regarding such acrylic rubber, for example, Patent Document 1 (Japanese Patent Laid-Open No. 50-156559) describes an acrylate monomer, a monomer having a halogen, a monomer component composed of β-cyanoalkyl acrylate, water, and an alkyl as an emulsifying agent. Phenoxypoly (ethyleneoxy) ethyl phosphate was mixed and emulsified, and paramentan hydroperoxide was added to carry out emulsion polymerization. The emulsion was coagulated and isolated using a 2% by weight solution of magnesium sulfate, and then isolated. A method of producing a crumb-shaped acrylic rubber by washing with warm water at 80 ° C. three times and drying under vacuum is disclosed. However, in the emulsion polymerization reaction and the coagulation reaction using a monovalent phosphoric acid ester as an emulsifier in this method, it is difficult to form a stable emulsion or crumb, 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 emulsifier remaining in the acrylic rubber cannot be sufficiently removed and reduced, and there is a problem that the storage stability and water resistance of the obtained rubber product are inferior. Further, since the crumb-shaped acrylic rubber produced has strong adhesiveness, there is a problem that workability and storage stability are inferior.

Further, in Patent Document 2 (International Publication No. 2018/10146 pamphlet), a monomer component composed of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate and monoethyl fumarate, water, and poly as an emulsifier An oxyalkylene alkyl ether phosphoric acid ester is charged, sodium ascorbate and potassium persulfate are added, and the emulsion polymerization solution obtained by emulsion polymerization reaction at normal pressure and room temperature is coagulated with an aqueous sodium sulfate solution, washed with water, dried and clam-like acrylic. A method of producing rubber is disclosed. However, the crumb-shaped acrylic rubber obtained by this method has problems that it is inferior in storage stability and water resistance, and has strong adhesiveness 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 contained in pure water, sodium lauryl sulfate and polyoxy. Emulsified using an emulsifier made of ethylene dodecyl ether, and emulsion polymerization is carried out in the presence of a polymerization initiator to a polymerization conversion rate of 95% by weight to obtain an emulsion polymerization solution, and sodium sulfate is continuously added thereto to obtain a hydrous crumb. Then, the produced hydrous crumb was washed with industrial water four times, with pH 3 acid washed once and once with pure water, and then dried at 110 ° C. for 1 hour in a hot air dryer. Therefore, a method for obtaining an acrylic rubber having a small residual amount of an emulsifier or a coagulant and having excellent water resistance (volume change after immersion in 80 ° C. distilled water for 70 hours) is disclosed. However, recently, acrylic rubber is required to have a higher degree of water resistance, and it is often the case that the requirement cannot be satisfied. Further, this Patent Document 3 does not describe that acrylic rubber is molded into a sheet shape or a veil shape and is used, and it is assumed that the adhesive acrylic rubber is treated in a crumb shape. Has a problem of inferior workability and storage stability.

On the other hand, regarding sheet rubber, for example, Patent Document 4 (Japanese Unexamined Patent Publication No. 1-225512) includes a twin-screw extruder including a feed barrel, a dehydration barrel, a standard barrel, a vent barrel and a vacuum barrel. Nitrile rubber (NBR) crumb with a water content of about 50% is supplied to the feed barrel, most of the water is dehydrated in the dehydration barrel, and the residual water and vaporized vaporized material are sucked and removed in the vacuum barrel, and then passed through the breaker plate and the die part. A method of continuously extruding into a strip is disclosed. Then, 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 having excellent storage stability and water resistance and a method for obtaining the acrylic rubber sheet.

Japanese Unexamined Patent Publication No. 50-156559 International Publication No. 2018/10146 Pamphlet International Publication No. 2018/079783 Pamphlet Japanese Unexamined Patent Publication No. 1-225512

The present invention has been made in view of the above problems, and an acrylic rubber sheet having excellent storage stability and water resistance, an efficient production method thereof, a rubber mixture produced from the acrylic rubber sheet, and a crosslink thereof. It is an object of the present invention to provide a rubber crosslinked product.

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

On the other hand, the present inventors also use an acrylic rubber sheet containing an ash having a large ratio of magnesium and phosphorus due to insufficient cleaning of the coagulant and an acrylic rubber sheet containing an ash containing a large amount of monovalent metal such as phosphorus and sodium. The effect of the present invention that the storage stability and water resistance are deteriorated and that the storage stability and water resistance are excellent is the complex viscosity, specific gravity, gel amount, pH, and glass transition of the acrylic rubber sheet at a specific temperature. It has been 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 also solidify an emulsion polymerization solution obtained by emulsifying and polymerizing a monomer component containing a (meth) acrylic acid ester as a main component in the presence of a divalent phosphoric acid-based emulsifier with a magnesium salt. The hydrous crumb produced in the above process can be easily manufactured by dehydrating, drying and molding with a specific screw type extruder after cleaning and extruding a sheet-like dried product. Furthermore, this acrylic rubber sheet is used to manufacture an acrylic rubber bale. It has been found that not only is it particularly suitable for the above, but it can also be used to obtain a good rubber mixture or rubber crosslinked product.

The present inventors can further adjust the shape and crumb diameter of the hydrous crumb generated by selecting the addition method of the coagulation reaction, the coagulation liquid concentration, the coagulation liquid temperature, the coagulant rotation speed, the peripheral speed, and the like within a specific range. Most of the coagulants used can be removed by washing those hydrous crumbs with warm water, while the phosphate-based emulsifier undergoes a coagulation reaction with a magnesium-based coagulant, causing salt exchange in the crumbs as magnesium phosphate. Although it remains in the water and can hardly be removed by the cleaning process, the magnesium phosphate salt can be efficiently removed by squeezing (dehydrating) water from the hydrous crumb, and it is dehydrated, dried and molded by a specific screw type extruder. It was found that the amount of gel in the obtained acrylic rubber can be reduced, and an acrylic rubber sheet having a large specific gravity that does not bite air and has 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, it is composed of acrylic rubber containing (meth) acrylic acid ester as a main component and having 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 as a ratio 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. It is also preferably formed from other copolymerizable monomers used as needed. In the present 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 of the complex viscosity at 100 ° C. ([η] 100 ° C.) to the complex viscosity at 60 ° C. ([η] 60 ° C.) ([η] 100 ° 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 amount of gel 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, an emulsion polymerization containing a (meth) acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid-based emulsifier and emulsion-polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization solution. Steps, a coagulation step of contacting the obtained emulsion polymerization solution with a magnesium salt aqueous solution as a coagulant to generate a hydrous crumb, a cleaning step of cleaning the produced hydrous crumb, and a dehydration slit for the washed hydrous crumb. Using a dehydration barrel, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip, the dehydration barrel dehydrates to a water content of 1 to 40% by weight, and then the drying barrel dries to less than 1% by weight to form a sheet. A method for producing an acrylic rubber sheet including a dehydration / drying / molding step of extruding a dried rubber from a die is provided.

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

The rotation 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 rotation speed of the magnesium salt aqueous solution is represented by the rotation speed of the stirring blade of the stirrer provided in the coagulation tank containing the magnesium salt aqueous solution, and the peripheral speed is represented by the rotation line speed 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 water-containing crumb obtained in the above solidification step with warm water, particularly hot water at 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) are further satisfied in the dehydration / drying / molding step using a screw type extruder. Preferably, it is preferable that all the conditions are optimally satisfied.
(A) The number of revolutions (N) of the screw type extruder is in the range of 10 to 1,000 rpm. (B) The extrusion amount (Q) of the screw type extruder is 100 to 1,500 kg / hr. (C) The temperature of the drying barrel portion of the screw type extruder is in the range of 100 to 250 ° C. (d) The degree of decompression of the drying barrel portion of the screw type extruder is in the range of 1 to 50 kPa (e). ) The resin pressure of the die part of the screw type extruder is in the range of 0.1 to 10 MPa.

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

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

According to the present invention, an acrylic rubber sheet having excellent storage stability and water resistance and a method for efficiently producing the acrylic rubber sheet are provided, and further, an acrylic rubber having excellent storage stability and water resistance obtained from the acrylic rubber sheet is provided. A rubber mixture and a rubber crosslinked 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 manufacturing 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 transport type cooling apparatus used as the cooling apparatus of FIG.

The acrylic rubber sheet of the present invention is composed of acrylic rubber containing (meth) acrylic acid ester as a main component and having a weight average molecular weight (Mw) of 100,000 to 5,000,000, and has 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 as a ratio 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 it is in the range of 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 ratio of the (meth) acrylic acid ester in the acrylic rubber is appropriately selected depending on the intended use, but is usually 50% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more. As the acrylic rubber constituting the acrylic rubber sheet of the present invention, one containing a reactive monomer is suitable because it can highly improve heat resistance, compression set resistance, and the like.

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

The (meth) acrylic acid alkyl ester usually includes a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms, preferably a (meth) acrylic acid alkyl ester having an 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 such (meth) acrylic acid alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, and n (meth) acrylic acid. -Butyl, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, etc., ethyl (meth) acrylate, (meth) acrylic N-butyl acid acid is preferable, and ethyl acrylate and n-butyl acrylate are more preferable.

The (meth) acrylate alkoxyalkyl ester is usually a (meth) acrylate alkoxyalkyl ester having 2 to 12 alkoxyalkyl groups, preferably a (meth) acrylate alkoxyalkyl ester having 2 to 8 alkoxyalkyl groups. , More preferably a (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) acrylate, methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, and (meth). Examples thereof include ethoxymethyl acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, and butoxyethyl (meth) acrylate. 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 (meth) acrylic acid ester selected from the group consisting of these (meth) acrylic acid alkyl esters and (meth) acrylic acid alkoxyalkyl esters can be used alone or in combination of two or more, and acrylic. 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 (meth) acrylic acid ester in the monomer component is excessively small, the weather resistance, heat resistance, and oil resistance of the obtained acrylic rubber may decrease, which is not preferable.

On the other hand, the reactive monomer is appropriately selected according to the purpose of use without any particular limitation, and for example, at least one functional group selected from the group consisting of a carboxyl group, an epoxy group and a halogen group may be selected. A monomer having a carboxyl group is preferable, and a monomer having a carboxyl group is particularly preferable. Further, in order to highly enhance the water resistance, a monomer having an ionic reactive group such as a carboxyl group or an epoxy group is suitable.

As the monomer having a carboxyl group, an ethylenically unsaturated carboxylic acid can be preferably used. Examples of the ethylenically unsaturated carboxylic acid include ethylenically unsaturated monocarboxylic acid, ethylenically unsaturated dicarboxylic acid, and ethylenically unsaturated dicarboxylic acid monoester, and among these, ethylenically unsaturated dicarboxylic acid monoester. It is preferable that the ester can further enhance the compression-resistant permanent strain characteristics when the acrylic rubber is used as a rubber cross-linked product.

As the ethylenically unsaturated monocarboxylic acid, an ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms is preferable, and examples thereof include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, and silicic acid. be able to. Further, as the ethylenically unsaturated dicarboxylic acid, an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms is preferable, and for example, butenedioic acid such as fumaric acid and maleic acid, itaconic acid, citraconic acid, and chloromaleic acid are used. Can be mentioned. The ethylenically unsaturated dicarboxylic acid referred to here includes those existing as anhydrides.

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 of 6 and an alkyl monoester having 2 to 8 carbon atoms, more preferably an alkyl monoester having 2 to 6 carbon atoms of buthendioic 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, and monocyclopentyl fumarate. Monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monoalkyl ester of butenedionate such as monocyclohexyl maleate; monomethyl itaconate, monoethyl itaconate, monon-butyl itaconate, monocyclohexyl itaconate Acid monoalkyl esters; etc. are mentioned, and 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 an epoxy group-containing (meth) acrylic acid ester such as glycidyl (meth) acrylate; an epoxy group-containing vinyl ether 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 such a halogen group include unsaturated alcohol esters of halogen-containing saturated carboxylic acids, (meth) acrylic acid haloalkyl esters, (meth) acrylic acid haloacyloxyalkyl esters, and (meth) acrylic acids (haloacetyls). Carbamoyloxy) alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, haloacetyl group-containing unsaturated monomers and the like. Specific examples of these unsaturated alcohol esters of halogen-containing saturated carboxylic acids include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate.

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. , (Meta) acrylic acid 2,3-dichloropropyl and the like.

Specific examples of the (meth) acrylic acid haloacyloxyalkyl ester include (meth) acrylic acid 2- (chloroacetoxy) ethyl, (meth) acrylic acid 2- (chloroacetoxy) propyl, and (meth) acrylic acid 3- (chloro). Examples thereof include acetoxy) propyl and 3- (hydroxychloroacetoxy) propyl (meth) acrylate. Specific examples of the (meth) acrylic acid (haloacetylcarbamoyloxy) alkyl ester include (meth) acrylic acid 2- (chloroacetylcarbamoyloxy) ethyl and (meth) acrylic acid 3- (chloroacetylcarbamoyloxy) propyl. 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, 3-chloropropyl allyl ether and the like. Specific examples of the halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, 2-chloroethyl allyl ketone and the like.

Specific examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl-α-methylstyrene. 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) propylallyl ether, p-vinylbenzylchloroacetic acid ester and the like.

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 diene and non-conjugated diene. 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, and 2-dicyclopentadienyl ethyl (meth) acrylate.

These reactive monomers are used alone or in combination of two or more, and the proportion of the reactive monomers in the acrylic rubber is usually 0.01 to 20% by weight, preferably 0.1 to 1% 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-mentioned monomer (hereinafter referred to as "other monomer") can be used together with the above-mentioned monomer.

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

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

The other monomers described above may be 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 0. It is in the range of 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 (meth) acrylic acid ester as a main component, and the content thereof may be appropriately selected according to the intended use of the target product, but is usually 50. By weight or more, preferably 70% by weight or more, more preferably 80% by weight or more.

The acrylic rubber constituting the acrylic rubber sheet of the present invention contains (meth) acrylic acid ester as a main component, but those having a reactive group are preferable.

The reactive group is appropriately selected depending on the intended use without any particular limitation, but 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, it is suitable because the crosslinked property of the acrylic rubber sheet can be highly improved. Further, as the reactive group, when it is an ionic reactive group such as a carboxyl group or an epoxy group, the water resistance can be particularly improved, which is preferable. As the acrylic rubber having such a reactive group, a reactive group may be imparted to the acrylic rubber by a post-reaction, but a copolymer of a reactive monomer (reactive group-containing monomer) is preferable. preferable.

The content of the reactive group may be appropriately selected according to the purpose of use, but 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. Workability, strength characteristics, compressive permanent strain resistance, oil resistance, when in the range of 0.01 to 3% by weight, particularly preferably 0.05 to 1% by weight, most preferably 0.1 to 0.5% by weight. It is suitable because the characteristics such as cold resistance and water resistance are highly balanced.

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. Consists of reactive monomers and other monomers used as needed, each of which is from the group consisting of the main components (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester. The binding 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, and particularly preferably 87 to 9% by weight. In the range of 99% by weight, 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, particularly. It is preferably in the range of 1 to 3% by weight, and the binding 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, and particularly preferably 0 to 15% by weight. It is in the range of 0 to 10% by weight. By setting the weight ratio of each of the above-mentioned monomers constituting the acrylic rubber within this range, the object of the present invention can be highly achieved, and when the acrylic rubber sheet is a crosslinked product, water resistance and compression resistance permanent strain resistance are obtained. It is suitable because it is significantly improved.

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

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, but is high as measured by GPC-MALS. Acrylic rubber bale processability and strength characteristics are generally in the range of 1.1 to 8, preferably 1.2 to 7, and more preferably 1.4 to 6 in an absolute molecular weight distribution with an emphasis on the molecular region. It is suitable because it is highly balanced.

The ratio (Mz / Mw) of the z average molecular weight (Mz) and the weight average molecular weight (Mw) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, but is measured by GPC-MALS. The processability and strength of the acrylic rubber sheet when the absolute molecular weight distribution is focused on the high molecular weight region and is usually in the range of 1.3 or more, preferably 1.4 to 5, more preferably 1.5 to 2. It is suitable because the characteristics are highly balanced and changes in physical properties (particularly strength characteristics) during storage can be mitigated.

In the acrylic rubber sheet of the present invention, the glass transition temperature (Tg) of the acrylic rubber constituting the sheet is usually 20 ° C. or lower, preferably 10 ° C. or lower, and more preferably 0 ° C. or lower, although there is no particular limitation. The lower limit of the glass transition temperature (Tg) of acrylic rubber is not particularly limited, but is usually −80 ° C. or higher, preferably −60 ° C. or higher, and more preferably −40 ° C. or higher. By setting the glass transition temperature to the lower limit or higher, the oil resistance and heat resistance can be improved, and by setting the glass transition temperature to the upper limit or lower, the cold resistance and workability can be improved.

<Acrylic rubber sheet>
The acrylic rubber sheet of the present invention is made of the acrylic rubber, and is characterized in that the ash content and the ash content 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 in 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, and more preferably 0.001% by weight or more. Especially, when it is 0.005% by weight or more, most preferably 0.01% by weight or more, the metal adhesion of the acrylic rubber sheet is reduced, and the operability, handleability and the like are excellent. Is.

The amount of ash that 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. It 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, and particularly preferably 80% by weight, in proportion to the total ash content. When it is% or more, storage stability and water resistance are highly excellent and suitable.

The ratio of magnesium to phosphorus ([Mg] / [P]) 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 by weight. Is preferably in the range of 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, and more preferably 0.6% by weight or less. Is optimized and has excellent properties such as heat resistance and water resistance, which is 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 gel amount of the acrylic rubber sheet of the present invention is not particularly limited, but is an insoluble content of methyl ethyl ketone, and is usually 50% by weight or less, more preferably 30% by weight or less, particularly preferably 10% by weight or less, and most preferably. When it is 5% by weight or less, the workability is highly improved and is suitable.

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. The storage stability is highly improved and is suitable.

The complex viscosity ([η] 60 ° C.) of the acrylic rubber sheet of the present invention at 60 ° C. 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 2,700 to 5,500 Pa · s, which is excellent in processability, oil resistance and shape retention.

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, When it is in the range of 000 Pa · s, more preferably 2,500 to 4,000 Pa · s, and most preferably 2,500 to 3,500 Pa · s, it is excellent in processability, oil resistance, and shape retention. ..

The ratio of the complex viscosity ([η] 100 ° C.) of the acrylic rubber sheet of the present invention at 100 ° C. to the complex viscosity ([η] 60 ° C.) at 60 ° C. ([η] 100 ° C./[η] 60 ° C.) 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 and suitable.

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

The thickness of the acrylic rubber sheet of the present invention is appropriately selected depending on the intended use, but is usually in the range of 1 to 45 mm, preferably 2 to 40 mm, more preferably 3 to 25 mm, and particularly preferably 3 to 20 mm. In particular, when a low-priced acrylic rubber sheet is produced by significantly improving productivity, the thickness is usually in the range of 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 intended use, but is particularly excellent in handleability when it is usually in the range of 300 to 1200 mm, preferably 400 to 1000 mm, and more preferably 500 to 800 mm. Suitable.

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

<Manufacturing method of acrylic rubber sheet>
The method for producing the acrylic rubber sheet is not particularly limited, but for example, a monomer component containing (meth) acrylic acid ester as a main component is emulsionized with water and a divalent phosphoric acid-based emulsifier and polymerized. The emulsion polymerization step of obtaining an emulsion polymerization solution by emulsion polymerization in the presence of a catalyst, the coagulation step of contacting the obtained emulsion polymerization solution with a magnesium salt aqueous solution as a coagulant to generate a hydrous crumb, and the produced hydrous crumb. The washing step of washing and the washed water-containing crumb were dehydrated to a water content of 1 to 40% by weight in the 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 the steps of dehydration, drying and molding in which the sheet-shaped dried rubber is later dried in a drying barrel to less than 1% by weight and extruded from the die.

Hereinafter, preferred embodiments of each of the above 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 weight component containing (meth) acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid emulsifier, and emulsion polymerization is carried out in the presence of a polymerization catalyst. The emulsion polymer solution is obtained.

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

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

Examples of the alkyloxypolyoxyalkylene phosphate or its salt include an alkyloxypolyoxyethylene phosphate or a salt thereof, an alkyloxypolyoxypropylene phosphate or a salt thereof, and among these, alkyloxy. A polyoxyethylene phosphate ester or a salt thereof is preferable.

Specific examples of the alkyloxypolyoxyethylene phosphate or its salt preferably used include octyloxydioxyethylene phosphate, octyloxytrioxyethylene phosphate, octyloxytetraoxyethylene phosphate, and decyl. Oxytetraoxyethylene Phosphate, Dodecyloxytetraoxyethylene Phosphate, Tridecyloxytetraoxyethylene Phosphate, Tetradecyloxytetraoxyethylene Phosphate, Hexadecyloxytetraoxyethylene Phosphate, Octadecyloxytetra Oxyethylene Phosphate, Octyloxypentaoxyethylene Phosphate, Decyloxypentaoxyethylene Phosphate, Dodecyloxypentaoxyethylene Phosphate, Tridecyloxypentaoxyethylene Phosphate, Tetradecyloxypentaoxyethylene Phosphate Acid ester, hexadecyloxypentaoxyethylene phosphate ester, octadecyloxypentaoxyethylene phosphate ester, octyloxyhexaoxyethylene phosphate ester, decyloxyhexaoxyethylene phosphate ester, dodecyloxyhexaoxyethylene phosphate 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 their metal salts, preferably those metal salts, more preferably their alkali metal salts, and most preferably their sodium salts.

Specific examples of the above alkyloxypolyoxypropylene phosphate or its salt include, for example, octyloxydioxypropylene phosphate, octyloxytrioxypropylene phosphate, octyloxytetraoxypropylene phosphate, and decyloxytetra. Oxypropylene phosphate, dodecyloxytetraoxypropylene phosphate, tridecyloxytetraoxypropylene phosphate, tetradecyloxytetraoxypropylene phosphate, hexadecyloxytetraoxypropylene phosphate, octadecyloxytetraoxypropylene Phosylate, octyloxypentaoxypropylene phosphate, decyloxypentaoxypropylene phosphate, dodecyloxypentaoxypropylene phosphate, tridecyloxypentaoxypropylene phosphate, tetradecyloxypentaoxypropylene phosphate Estel, Hexadecyloxypentaoxypropylene Phosphate, Octadecyloxypentaoxypropylene Phosphate, Octyloxyhexaoxypropylene Phosphate, Decyloxyhexaoxypropylene Phosphate, Dodecyloxyhexaoxypropylene Phosphate, Tridecyl Oxyhexaoxypropylene phosphate ester, tetradecyloxyhexaoxypropylene phosphate ester, hexadecyloxyhexaoxypropylene phosphate ester, octadecyloxyhexaoxypropylene phosphate ester, octyloxyoctoxypropylene phosphate ester, decyloxyoctaoxy Protinic Phosphate, Dodecyloxyoctaoxypropylene Phosphate, Tridecyloxyoctaoxyethylene Phosphate, Tetradecyloxyoctaoxypropylene Phosphate, Hexadecyloxyoctaoxypropylene Phosphate, Octadecyloxyoctaoxypropylene Phosphate Examples thereof include acid esters and the like, and metal salts thereof, preferably those metal salts, more preferably those alkali metal salts, and most preferably their sodium salts.

Specific examples of the above-mentioned alkylphenyloxypolyoxyalkylene phosphate or its salt include alkylphenyloxypolyoxyethylene phosphate or its salt, alkylphenyloxypolyoxypropylene phosphate or its salt, and the like. Of these, alkylphenyloxypolyoxyethylene phosphate salts are preferable.

Specific examples of suitable alkylphenyloxypolyoxyethylene phosphate or salts thereof include methyloxyoxytetraoxyethylene phosphate, ethylphenyloxytetraoxyethylene phosphate, butylphenyloxytetraoxyethylene phosphate, and the like. Hexylphenyloxytetraoxyethylene Phosphate, Nonylphenyloxytetraoxyethylene Phosphate, Dodecylphenyloxytetraoxyethylene Phosphate, Octadecyloxytetraoxyethylene Phosphate, Methylphenyloxypentaoxyethylene Phosphate, Ethyl Phenyloxypentaoxyethylene Phosphate, Butylphenyloxypentaoxyethylene Phosphate, Hexylphenyloxypentaoxyethylene Phosphate, Nonylphenyloxypentaoxyethylene Phosphate, Dodecylphenyloxypentaoxyethylene Phosphate, Methylphenyloxyhexaoxyethylene phosphate ester, ethylphenyloxyhexaoxyethylene phosphate ester, butylphenyloxyhexaoxyethylene phosphate ester, hexylphenyloxyhexaoxyethylene phosphate ester, nonylphenyloxyhexaoxyethylene phosphate ester, Dodecylphenyloxyhexaoxyethylene Phosphate, Methylphenyloxyhexaoxyethylene Phosphate, Ethylphenyloxyoctaoxyethylene Phosphate, Butylphenyloxyoctaoxyethylene Phosphate, Hexylphenyloxyoctaoxyethylene Phosphate, Nonylphenyloxyoctaoxyethylene phosphate, etc., dodecylphenyloxyoctaoxyethylene phosphate and the like, and their metal salts are mentioned, preferably their metal salts, more preferably their alkali metal salts, most preferably them. It is a 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. Oxytetraoxypropylene Phosphate, Nonylphenyloxytetraoxypropylene Phosphate, Dodecylphenyloxytetraoxypropylene Phosphate, Methylphenyloxypentaoxypropylene Phosphate, Ethylphenyloxypentaoxypropylene Phosphate, Butylphenyl Oxypentaoxypropylene phosphate ester, hexylphenyloxypentaoxypropylene phosphate ester, nonylphenyloxypentaoxypropylene phosphate ester, dodecylphenyloxypentaoxypropylene phosphate ester, methylphenyloxyhexaoxypropylene phosphate ester, ethyl Phenyloxyhexaoxypropylene phosphate ester, butylphenyloxyhexaoxypropylene phosphate ester, hexylphenyloxyhexaoxypropylene phosphate ester, nonylphenyloxyhexaoxypropylene phosphate ester, dodecylphenyloxyhexaoxypropylene phosphate ester, methyl Phenyloxyoctaoxypropylene Phosphate, Ethylphenyloxyoctaoxypropylene Phosphate, Butylphenyloxyoctaoxypropylene Phosphate, Hexylphenyloxyoctaoxyethylene Phosphate, Nonylphenyloxyoctaoxypropylene Phosphate, Dodecyl Examples thereof include phenyloxyoctaoxypropylene phosphate and the like, and metal salts thereof. Among these, the above-mentioned metal salts are preferable, their alkali metal salts are more preferable, and their sodium salts are most preferable.

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. It is preferably in the range of 0.1 to 5 parts by weight, more preferably 1 to 3 parts by weight.

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

Other anionic emulsifiers include, for example, fatty acid emulsifiers such as myristic acid, palmitic acid, oleic acid, and linolenic acid; monovalent phosphoric acid emulsifiers such as di (alkyloxypolyoxyalkylene) phosphate ester salt; dodecylbenzene. Alkylbenzene sulfonic acid emulsifiers such as sodium sulfonate; sulfuric acid emulsifiers such as sodium lauryl sulfate can be mentioned. Among these, monovalent phosphoric acid emulsifiers and sulfuric acid emulsifiers are preferable, and monovalent phosphoric acid emulsifiers are particularly preferable. preferable.

Examples of the cationic emulsifier include alkyltrimethylammonium chloride, dialkylammonium chloride, and benzylammonium chloride.

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

Other emulsifiers other than these divalent phosphoric acid-based emulsifiers can be used individually or in combination of two or more, and the amount used thereof 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 emulsifier may be a conventional method, and examples thereof include a method of stirring the monomer, emulsifier, and water using a stirrer such as a homogenizer or a disc 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, and particularly preferably 15 to 150 parts by weight, based on 100 parts by weight of the monomer component. Most preferably, it is in the range of 20 to 80 parts by weight.

The polymerization catalyst used is not particularly limited as long as it is usually used in emulsion polymerization, and 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. As the peroxide, an inorganic peroxide or an organic peroxide is used.

Examples of the inorganic peroxide include sodium persulfate, potassium persulfate, hydrogen peroxide, ammonium persulfate and the like. Among these, potassium persulfate, hydrogen peroxide and 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 organic peroxide used in emulsion polymerization. For example, 2,2-di (4,5-di- (t-butylperoxy) cyclohexyl) propane, 1-di- (t-hexyl peroxy) cyclohexane, 1,1-di- (t-butyl peroxy) cyclohexane, 4,4-di- (t-butyl peroxy) n-butyl valerate, 2,2 -Di- (t-butylperoxy) butane, t-butylhydroperoxide, cumenehydroperoxide, diisopropylbenzenehydroperoxide, paramentanhydroperoxide, 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, disuccinate peroxide, dibenzoyl peroxide, di (3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide, Diisobutyryl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-tetramethylbutylper Oxyneodecanate, t-hexyl peroxypivalate, t-butylperoxyneodecanate, t-hexyl peroxypivarate, t-butylperoxypivarate, 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-butylperoxyisopropyl monocarbonate, t-buylperoxy-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, paramentan hydroperoxide, benzoyl peroxide and the like are preferable.

Examples of the azo compound include azobisisobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis [2- (2-imidazolin-2-yl) propane, 2, 2'-azobis (propan-2-carboamidine), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropaneamide], 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 can be mentioned.

These radical generators can be used individually or in combination of two or more, and the amount used is usually 0.0001 to 5 parts by weight, preferably 0, based on 100 parts by weight of the monomer component. It is in the range of 0005 to 1 part by weight, more preferably 0.001 to 0.5 part by weight.

As the reducing agent, any one used in the redox catalyst of emulsion polymerization can be used without particular limitation, but in the present invention, it is particularly preferable to use at least two kinds of reducing agents. As the at least two types of 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, and examples thereof include ferrous sulfate, sodium hexamethylenediamine tetraacetate, and cuprous naphthenate, and among these, ferrous sulfate is preferable. Each of these reduced metal ion compounds can be used alone or in combination of two or more, and the amount used is usually 0.000001 to 0. With respect to 100 parts by weight of the monomer component. It is in the range of 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, but is, for example, ascorbic acid such as ascorbic acid, sodium ascorbate, potassium ascorbate or a salt thereof; erythorbic acid, sodium erythorbicate, erythorbin. Elysorbic acid such as potassium acid or a salt thereof; sulphinate such as sodium hydroxymethane sulfite; sodium sulfite, potassium sulfite, sodium hydrogen sulfite, aldehyde sodium bisulfite, potassium hydrogen sulfite sulfite; sodium pyrosulfite, potassium pyrosulfite Pyro sulfites such as sodium bisulfite and potassium hydrogen pyrosulfite; thiosulfates such as sodium thiosulfite and potassium thiosulfite; of sodium bisulfite, sodium bisulfite, potassium bisulfite, sodium hydrogen phosphite, potassium hydrogen phosphite Pyrophosphoric acid or a salt thereof; pyroaphosphate or a salt thereof such as pyrophosphate, sodium pyrophosphate, potassium pyrophosphate, sodium bisulfite, potassium hydrogenpyrophosphate and the like; sodium formaldehyde sulfoxylate and the like. Among these, alcorbic acid or a salt thereof, sodium formaldehyde sulfoxylate and the like are preferable, and ascorbic acid or a salt thereof is particularly preferable.

The reducing agents other than the metal ion compounds in the reduced state can be used individually or in combination of two or more, and the amount used is usually 0.001 to 0.001 to 100 parts by weight of the monomer component. It is in the range of 1 part by weight, preferably 0.005 to 0.5 parts by weight, and more preferably 0.01 to 0.3 parts by weight.

The ratio of the combination of the metal ion compound in the reducing state and the other reducing agent is not particularly limited, but [the metal ion compound in the reducing state] / [the reducing agent other than the metal ion compound in the reducing state]. When the weight ratio is usually in the range of 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. It is suitable because the productivity can be highly improved.

A preferable combination of the metal ion compound in the reduced state and the other reducing agent is a combination of ferrous sulfate and ascorbic acid or a salt thereof and / or sodium formaldehyde sulfoxylate, and more preferably ferrous sulfate. A combination of ascorbate and / or sodium formaldehyde sulfoxylate, most preferably a combination of ferrous sulfate and alcorbate. 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, based on 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 part by weight, preferably 0.001 to 1 part by weight, based on 100 parts by weight of the monomer component. Is in the range of 0.005 to 0.5 parts by weight, more preferably 0.01 to 0.3 parts by weight.

The amount of water used in the emulsion polymerization reaction may be limited to that used during the emulsionization of the monomer component, but is usually 1 to 1000 parts by weight, preferably 5 to 5 parts by weight, based on 100 parts by weight of the monomer component used for 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 method may be a conventional method, and may be a batch type, a semi-batch type, or a continuous type. The polymerization temperature and the polymerization time are not particularly limited and can be appropriately selected from the type of polymerization initiator used and the like. The polymerization temperature is usually in the range of 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 excellent in the strength characteristics of the acrylic rubber sheet usually produced when it is usually 80% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more. Moreover, there is no monomeric odor and it is suitable. A polymerization inhibitor 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 solution obtained in the above emulsion polymerization step is brought into contact with a magnesium salt aqueous solution as a coagulant to form a hydrous crumb.

The solid content concentration of the emulsion polymerization solution used at the time of coagulation is not particularly limited, but is usually adjusted to the range of 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 and magnesium sulfate, and organic magnesium salts such as magnesium formate and magnesium acetate. Of these, inorganic agnesium salts are preferable, and magnesium sulfate is particularly preferable.

Each of these magnesium salts can be used alone or in combination of two or more, and the amount used is usually 0.01 to 100 parts by weight, preferably 0.% by weight, based on 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 acrylic rubber can be sufficiently solidified, and the compression-resistant permanent strain resistance and water resistance when the acrylic rubber is crosslinked can be highly improved, which is preferable. In the present invention, a coagulant other than the above magnesium salt may be used in combination as long as the effect of the present invention is not impaired.

When the magnesium salt concentration of the magnesium salt aqueous solution 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, of the hydrous crumb produced. It is suitable because the particle size can be focused uniformly in a specific region.

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

The method of contacting the emulsion polymerization solution with the magnesium salt aqueous solution is not particularly limited, but for example, a method of adding the emulsion polymerization solution to the stirred magnesium salt aqueous solution, or a method of adding the emulsion polymerization solution to the stirred emulsion polymerization solution. Any method of adding an aqueous solution may be used, but a method of adding an emulsion polymerization solution to a stirred magnesium salt aqueous solution can improve the shape and crumb diameter of the hydrous crumb to be produced, and can be used as an emulsifier or coagulation in a later step. It is suitable because the cleaning efficiency of the agent can be remarkably improved.

The stirring speed (rotation speed) of the magnesium salt aqueous solution being stirred, that is, the rotation 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. Since the crumb particle size can be made small and uniform, a rotation speed of 100 rpm or more is usually suitable, preferably 200 to 1,000 rpm, more preferably 300 to 900 rpm, particularly preferably 350 to 850, and most preferably 400 to 800 rpm. Is the range of. If the stirring speed (rotation speed) of the magnesium salt aqueous solution is excessively low and the flow velocity is slow, a large crumb particle size and a small crumb particle size will be produced, and if it is excessively 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, that is, the speed of the outer circumference of the stirring blade of the stirring device, and although there is no particular limitation, as already mentioned, the water-containing crumb particle size produced by the vigorous stirring Is suitable because it can be made small and uniform, and 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, 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. It is suitable because the solidification reaction can be easily controlled.

In the present invention, the rotation speed (stirring speed) of the magnesium salt-containing water-soluble system in the coagulation step is defined as the rotation speed of the magnesium salt-containing aqueous solution with the rotation speed of the stirring blade provided in the coagulation tank containing the coagulant. The peripheral speed of the magnesium salt-containing water-based system is defined as the peripheral speed of the aqueous solution by the rotational speed of the outer circumference of the stirring blade.

(Washing process)
The cleaning step in the method for producing an acrylic rubber sheet of the present invention is a step of cleaning the hydrous crumb generated in the solidification step.

The cleaning method is not particularly limited and may follow a conventional method. For example, the produced hydrous 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 50 parts by weight, based on the monomer component 100. When it is in the range of 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 cleaning step is not particularly limited, but it is preferable that the cleaning efficiency is improved when warm water is used. The temperature of the hot water is not particularly limited, but is preferably 40 ° C. or higher, preferably 40 to 100 ° C., more preferably 50 to 90 ° C., and most preferably 60 to 80 ° C., because the cleaning efficiency can be significantly increased. Is. By setting the temperature of the washing water to the above lower limit or higher, the emulsifier and the coagulant are released from the hydrous crumb to further improve the washing efficiency.

The washing time is not particularly limited, but is usually in the range of 1 to 120 minutes, preferably 2 to 60 minutes, and 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, and 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 washings with water is large, but the shape of the water-containing crumb and the diameter of the water-containing crumb should be adjusted within a specific range. And / or by setting the cleaning temperature within the above range, the number of cleanings can be significantly reduced.

(Dehydration / drying / molding process)
The dehydration / drying / molding step in the method for producing an acrylic rubber sheet of the present invention is a screw comprising a dehydration barrel having a dehydration slit, a drying barrel for drying under reduced pressure, and a die at the tip of the washed water-containing crumb. It is characterized in that a sheet-shaped dried rubber is extruded by dehydrating, drying and molding using a mold 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, providing a draining step for separating free water from the water-containing crumb after washing with a draining machine after the washing step and before the dehydration / drying step improves dehydration efficiency. It is suitable for raising.

As the drainer, a known one can be used without particular limitation, and examples thereof include a wire mesh, a screen, an electric sieve, and the like, preferably a wire mesh and a screen. The opening of the drainer is not particularly limited, but when it is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm, the water content crumb loss is small. Moreover, it is suitable because it can drain water efficiently.

The water content of the water-containing crumb after draining, that is, the water content of the water-containing crumb 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 hydrous crumb after draining, that is, the temperature of the hydrous crumb to be put into 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 preferably, when the temperature is in the range of 55 to 85 ° C., most preferably 60 to 80 ° C., a rubber having a high specific heat of 1.5 to 2.5 KJ / kg · K and difficult to raise the temperature like the acrylic rubber of the present invention. It is suitable because the hydrous crumb can be efficiently dehydrated and dried using a screw type extruder.

Dehydration of hydrous crumbs (dehydration barrel)
In the present invention, dehydration of the hydrous crumb is performed in a dehydration barrel portion having a dehydration slit provided in the screw type extruder. The opening of the dehydration slit may be appropriately selected according to the conditions of use, but is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1.0 mm, and more preferably 0.2 to 0.6 mm. At a certain time, it is preferable that the water-containing crumbs are less lost and the water-cutting crumbs can be efficiently dehydrated. The number of dehydration barrels in this screw type extruder is not particularly limited, but when the number is usually a plurality, preferably 2 to 10 or more preferably 3 to 6, the adhesive acrylic rubber is efficiently dehydrated. Suitable for the above.

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

When using a screw type extruder equipped with a plurality of dehydration barrels, it is preferable to combine drainage (dehydration) and exhaust steam (pre-drying) because dehydration of the adhesive acrylic rubber and reduction of water content can be efficiently performed. Is. In a screw type extruder equipped with three or more dehydration barrels, the selection of whether each dehydration barrel is a drainage type dehydration barrel or a steam exhaust type dehydration barrel may be appropriately performed according to the purpose of use, but is usually manufactured. It is appropriate to increase the number of drainage barrels to reduce the amount of ash in the acrylic rubber, and to increase the number of steam exhaust type barrels to reduce the water content.

The set temperature of the dehydration barrel is appropriately selected depending on the type of acrylic rubber, ash content, water content, operating conditions, etc., but is usually 60 to 150 ° C., preferably 70 to 140 ° C., more preferably 80 to 130 ° C. The range. The set temperature of the dehydration barrel for dehydration in the drained state is usually 60 ° C. to 120 ° C., preferably 70 to 110 ° C., more preferably 80 to 100 ° C., and the set temperature of the dehydration barrel for pre-drying in the exhausted steam state is , Usually in the range of 100 to 150 ° C., preferably 105 to 140 ° C., more preferably 110 to 130 ° C.

The water content after dehydration for squeezing water from the water content crumb, that is, the water content after passing through the drainage 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 to 10 to 35% by weight is preferable because the ash removal efficiency and productivity are highly balanced.
It is suitable because it can be a dry crumb in a state in which it contains almost no water (water content is less than 1% by weight) in a drying barrel under reduced pressure in the next step.

When dehydrating acrylic rubber with strong adhesiveness using a centrifuge or the like, the acrylic rubber adheres to the dehydration slit and can hardly be dehydrated (the water content is reduced only to about 45 to 55% by weight). In the present invention, it is preferable to use a screw type centrifuge having a dehydration slit and a dehydration barrel forcibly squeezed by a screw because the water content can be efficiently reduced to less than that.

When the screw type extruder is provided with the drain type dehydration barrel and the exhaust steam type dehydration barrel, the water content of the water content crumb in the drain type dehydration barrel portion is usually 5 to 45% by weight, preferably 10 to 10% by weight. It is 40% by weight, more preferably 15 to 35% by weight, and the water content after pre-drying in the exhaust steam type dehydration barrel portion is usually 1 to 30% by weight, preferably 3 to 20% by weight, more preferably 5 to 15%. It is% by weight.

Drying of hydrous crumbs (drying in the drying barrel)
In the present invention, the water-containing crumb after dehydration is dried in the drying barrel portion under reduced pressure provided on the downstream side of the dehydration barrel portion in the screw type extruder. The degree of decompression of the drying barrel may be appropriately selected, but it is preferable that the hydrous crumb can be efficiently dried when it is usually 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa.

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

The number of drying barrels in the screw type extruder is not particularly limited, but is usually a plurality, preferably 2 to 10 barrels, and more preferably 3 to 8 barrels. When there are a plurality of dry barrels, the degree of decompression may be an approximate degree of decompression for all the dry barrels, or may be changed. When having a plurality of drying barrels, the set temperature may be an approximate temperature for all the drying barrels or may be changed, but it is closer to the discharge part (closer to the die) than the temperature of the introduction part (closer to the dehydration barrel). It is preferable to raise 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 in a screw type extruder, when the water content of the acrylic rubber reaches this value (a state in which almost all water is removed) and melt extrusion is performed, the gel amount of the acrylic rubber is reduced and the entrained bubbles are prevented. It is important for reducing and increasing the specific gravity.

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

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

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

Operating conditions of the 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 3000 to 15000 mm, preferably 4000 to 10000 mm, and more preferably 4500. The range is ~ 8000 mm.

The screw diameter (D) of the screw type extruder used may be appropriately selected depending on the intended use, but is usually in the range of 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) to the screw diameter (D) of the screw type extruder used is not particularly limited, but is usually 10 to 100, preferably 20 to 80. It is preferable that the water content is less than 1% by weight without lowering the molecular weight or burning of the dried rubber when it is in the range of 30 to 60.

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. At ~ 300 rpm, the water content and gel amount of acrylic rubber can be efficiently reduced, which is preferable.

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

The ratio (Q / N) of the extrusion amount (Q) to the rotation speed (N) of the screw type 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, particularly preferably 4 to 6, because the adhesive acrylic rubber can be efficiently dehydrated, dried, and molded.

Sheet-shaped dry rubber The shape of the dry rubber extruded from the screw-type extruder is sheet-like, and at this time, the specific gravity can be increased without entraining air, and the storage stability of the obtained acrylic rubber sheet is highly improved, which is suitable. is there. The sheet-shaped dry rubber extruded from the screw-type extruder is cooled and then cut to a predetermined size as needed 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 in the range of 1 to 40 mm, preferably 2 to 35 mm, more preferably 3 to 30 mm, and most preferably 5 to 25 mm. It is suitable because it has excellent workability and productivity at some time. 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. It is preferably in the range of 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 depending on the intended use, but the width is usually in the range of 300 to 1200 mm, preferably 400 to 1000 mm, and 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 ° C. 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, and more preferably 0.6% by weight or less.

The complex viscosity ([η] 100 ° C.) of the sheet-shaped dry rubber extruded from the screw type extruder at 100 ° C. is not particularly limited, but is usually 1,500 to 6,000 Pa · s, preferably 2. Extrudability as a sheet and as a sheet when it is in the range of 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 shape is highly balanced and suitable. By setting the value of the complex viscosity ([η] 100 ° C.) at 100 ° C. to the lower limit or higher, the extrudability can be improved, and by setting the value to the upper limit or lower, the shape of the sheet-shaped dried rubber is deformed. Breakage can be suppressed.

The method for cooling the sheet-shaped dry rubber is not particularly limited and may be left at room temperature. However, since the heat conductivity of the sheet-shaped dry rubber is very small, 0.1-0.4, it is blown or cooled. Forced cooling such as an air-cooling method in the air, a watering method in which water is sprayed, or a dipping method in which water is immersed is preferable in order to increase productivity, and an air-cooling method under ventilation or cooling is particularly preferable.

In the air-cooled method of 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 can be conveyed and cooled while blowing cold air. The temperature of the cold air is not particularly limited, but is usually in the range of 0 to 30 ° C, preferably 5 to 25 ° C, and more preferably 10 to 20 ° C. The length to be cooled is not particularly limited, but is usually in the range of 5 to 500 m, preferably 10 to 200 m, and 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 more, more preferably 100 ° C./hr or more, and more preferably 150 ° C./hr or more. It is suitable.

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

The complex viscosity ([η] 60 ° C.) of the sheet-shaped dry rubber to be the acrylic rubber sheet according to the present invention at 60 ° C. is not particularly limited, but is usually 15,000 Pa · s or less, preferably 2,000. When it is in the range of ~ 10,000 Pa · s, more preferably 2,500 to 7,000 Pa · s, most preferably 2,700 to 5,500 Pa · s, it is possible to cut continuously without entraining air. Suitable.

Further, the ratio of the complex viscosity ([η] 100 ° C.) of the sheet-shaped dry rubber at 100 ° C. to the complex viscosity ([η] 60 ° C.) at 60 ° C. ([η] 100 ° C./[η] 60 ° C. ) 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, the air entrainment property is low, and cutting and productivity are highly balanced, which is preferable.

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

The acrylic rubber sheet of the present invention thus obtained is superior in operability and storage stability as compared with crumb-shaped acrylic rubber, and can be used as it is or laminated as described below and 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 bale produced from the acrylic rubber sheet of the present invention is not particularly limited, but the width is usually in the range of 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm in length. Is usually in the range of 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.

The above acrylic rubber veil water content, 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.), the ratio of the complex viscosity at 100 ° C. ([η] 100 ° C.) to the complex viscosity at 60 ° C. ([η] 60 ° C.) ([η] 100 ° C./[η] 60 ° C.) , And the characteristic values of Mooney viscosity (ML1 + 4,100 ° C.) 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 it, and laminating and integrating a plurality of them. Manufactured.

The laminating temperature of the sheet-shaped dry rubber is not particularly limited, but is preferably 30 ° C. or higher, preferably 35 ° C. or higher, more preferably 40 ° C. or higher, because air entrained during laminating can escape. The number of 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, and the acrylic rubber veil can be used as it is or by cutting the required amount and putting it in a kneader such as a vanbury or roll. Can be done.

<Rubber mixture>
The rubber mixture of the present invention is characterized in that the acrylic rubber sheet or the acrylic rubber veil is mixed with a filler and a cross-linking agent.

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

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, silica soil, zinc oxide, basic magnesium carbonate, active calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, calcium sulfate, barium sulfate and the like. be able to.

Each of these fillers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the effect of the present invention, and is used in 100 parts by weight of an acrylic rubber sheet or an 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, and more preferably 20 to 100 parts by weight.

The cross-linking agent constituting the rubber mixture may be appropriately selected depending on the type and application of the reactive group contained in the acrylic rubber sheet or acrylic rubber veil, and may be appropriately selected, but the acrylic rubber sheet or acrylic rubber may be appropriately selected. There is no particular limitation as long as the veil can be crosslinked, and for example, a polyvalent amine compound such as a diamine compound and a carbonate thereof; a sulfur compound; a sulfur donor; a triazinethiol compound; a polyvalent epoxy compound; an ammonium organic carboxylate. Conventionally known cross-linking 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, ammonium carboxylates, metal dithiocarbamic acid salts and triazinethiol compounds are preferable, hexamethylenediamine carbamate, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, and benzoate. Ammonium acid, 2,4,6-trimercapto-1,3,5-triazine is particularly preferred.

When the acrylic rubber sheet or acrylic rubber veil to be used is composed of a carboxyl group-containing acrylic rubber, it is preferable to use a polyvalent amine compound and a carbonate thereof as a cross-linking 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-Phenylenediisopropyridene) dianiline, 4,4'-(p-phenylenedi) Isopropylidene) dianiline, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminobenzanilide, 4,4'-bis (4-aminophenoxy) biphenyl, m-xyli Aromatic polyvalent amine compounds such as rangeamine, p-xylylenediamine, 1,3,5-benzenetriamine; and the like. Among these, hexamethylenediamine carbamate, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane and the like are preferable.

When the acrylic rubber sheet or acrylic rubber veil to be used is composed of epoxy group-containing acrylic rubber, aliphatic polyvalent amine compounds such as hexamethylenediamine and hexamethylenediamine carbamate and their carbonates; 4, Aromatic polyvalent amine compounds such as 4'-methylenedianiline; ammonium carboxylic acid salts such as ammonium benzoate and ammonium adipate; metal dithiocarbamic acid salts such as zinc dimethyldithiocarbamate; polyvalent carboxylic acids such as tetradecanedioic acid; A quaternary onium salt such as cetyltrimethylammonium bromide; an imidazole compound such as 2-methylimidazole; an isocyanuric acid compound such as ammonium isocyanurate; and the like can be used, and among these, ammonium carboxylic acid salt and metal dithiocarbamate salt are preferable. , Ammonium benzoate is more preferred.

When the acrylic rubber sheet or acrylic rubber veil to be 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 a cross-linking agent. Examples of the sulfur donor include dipentamethylene thiuram hexasulfide and triethyl thiuram disulfide. Examples of the triazine compound include 6-trimercapto-s-triazine, 2-anilino-4,6-dithiol-s-triazine, 1-dibutylamino-3,5-dimercaptotriazine, 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 Among these, 2,4,6-trimercapto-1,3,5-triazine is preferable.

Each of these cross-linking agents can be used alone or in combination of two or more, and the blending amount thereof is usually 0.001 to 20 parts by weight, preferably 0.001 to 20 parts by weight, based on 100 parts by weight of the acrylic rubber sheet or acrylic rubber veil. Is 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight. By setting the blending amount of the cross-linking agent within this range, it is possible to make the mechanical strength of the rubber cross-linked product excellent while making the rubber elasticity sufficient, which is preferable.

As the rubber mixture of the present invention, other rubber components other than the acrylic rubber sheet or the acrylic rubber veil can be used, if necessary. Other rubber components used as needed are not particularly limited, but include, for example, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicon rubber, fluororubber, and elastomer. Examples thereof include based elastomers, styrene-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, and polysiloxane-based elastomers.
These other rubbers can be used alone or in combination of two or more. The shape of these other rubbers may be any of veil shape, sheet shape, powder shape and 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 anti-aging agent can be added to the rubber mixture of the present invention, if necessary. The type of anti-aging agent is not particularly limited, but 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-triazine-2-ylamino) Phenolic anti-aging agents such as phenol; tris (nonylphenyl) phos Phenolic acid ester anti-aging agents such as phyto, diphenylisodecylphosphite, tetraphenyldipropylene glycol diphosphite; sulfur ester anti-aging agents such as dilauryl thiodipropionate; , 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, butylaldehyde-aniline condensates; imidazole-based antioxidants such as 2-mercaptobenzimidazole; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin, etc. Kinolin-based anti-aging agents; hydroquinone-based anti-aging agents such as 2,5-di- (t-amyl) hydroquinone; and the like. Of these, amine-based anti-aging agents are particularly preferable.

Each of these anti-aging agents can be used alone or in combination of two or more, and the blending amount thereof is usually 0.01 to 15 parts by weight with respect to 100 parts by weight of the acrylic rubber sheet or acrylic rubber veil. It is preferably in the range of 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 antiaging agent. The rubber mixture of the present invention further comprises other additives commonly used in the art, such as cross-linking aids, cross-linking accelerators, cross-linking retarders, silane coupling agents, plasticizers, processing aids, as required. Agents, lubricants, pigments, colorants, antistatic agents, foaming agents and the like can be arbitrarily blended. 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 a method for producing a rubber mixture of the present invention, a filler, a cross-linking agent and other rubber components that can be contained as needed, an antiaging agent and other compounding agents are mixed with the acrylic rubber sheet or the acrylic rubber veil of the present invention. Any means used in the conventional 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, the reaction or decomposition of a cross-linking agent that is a component that easily reacts or decomposes with heat can be performed. It is preferable to mix in a short time at a temperature at which it does not occur.

<Rubber crosslinked product>
The rubber crosslinked product of the present invention is obtained by cross-linking the above rubber mixture.

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

The rubber crosslinked 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 cross-linking varies depending on the heating method, cross-linking temperature, shape and the like, but is preferably carried out for 1 to 48 hours. The heating method and heating temperature may be appropriately selected.

The rubber crosslinked 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, seal for electric / electronic equipment, seal for air compression equipment, and the like. A unit cell equipped with a rocker cover gasket attached to the connecting portion between the cylinder block and the cylinder head, an oil pan gasket attached to 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 gaskets for top covers of hard disk drives mounted between a pair of sandwiched housings; cushioning material, vibration isolator; wire coating material; industrial belts; tubes and hoses; sheets It is preferably used as;

The rubber cross-linked product of the present invention is also used as an extruded molded product and a molded cross-linked product for automobile applications, for example, 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 suitably 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 and air conditioner hoses.

<Device configuration used for manufacturing acrylic rubber sheets>
Next, an apparatus configuration used for manufacturing an acrylic rubber sheet according to an embodiment of the present invention will be described. FIG. 1 is a diagram schematically showing an example of an acrylic rubber manufacturing system having an apparatus configuration used for manufacturing an acrylic rubber sheet according to an embodiment of the present invention. For the production of the acrylic rubber sheet according to the present invention, for example, the acrylic rubber production system 1 shown in FIG. 1 can be used.

The acrylic rubber manufacturing system 1 shown in FIG. 1 is composed of 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 bale device 7. ..

The emulsion polymerization reactor is configured to perform the treatment related to the emulsion polymerization step described above. Although not shown in FIG. 1, this emulsion polymerization reactor includes, for example, a polymerization reaction tank, a temperature control unit for controlling the reaction temperature, a motor, and a stirring device including a stirring blade. In the emulsion polymerization reactor, water and a divalent phosphoric acid emulsifier are mixed with a monomer component for forming acrylic rubber, emulsified while being appropriately stirred with a stirrer, and emulsion-polymerized in the presence of a polymerization catalyst. This makes it possible to obtain an emulsion polymerization solution. The emulsion polymerization reactor may be a batch type, a semi-batch type, or a continuous type, and may be any of a tank type reactor and a tube type reactor.

The coagulation device 3 shown in FIG. 1 is configured to perform the process related to the coagulation step described above. As schematically shown in FIG. 1, the coagulation device 3 includes, for example, a stirring tank 30, a heating unit 31 for heating the inside of the stirring tank 30, and a temperature control unit (not shown) for controlling the temperature inside the stirring tank 30. It has a stirring device 34 including 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 apparatus 3, a hydrous crumb can be produced by bringing the emulsion polymerization solution obtained by the emulsion polymerization reactor into contact with the coagulation solution and coagulating it.

In the coagulation apparatus 3, for example, for the contact between the emulsion polymerization solution and the magnesium salt aqueous solution, a method of adding the emulsion polymerization solution to the stirring magnesium salt aqueous solution is adopted. That is, a hydrous crumb is generated by filling the stirring tank 30 of the coagulation device 3 with an aqueous magnesium salt solution and adding and contacting the aqueous emulsion of the emulsion with the emulsion to coagulate the emulsion.

The heating unit 31 of the coagulation device 3 is configured to heat the magnesium salt aqueous solution filled in the stirring tank 30. Further, 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 so as to be usually in the range of 40 ° C. or higher, preferably 40 to 90 ° C., and more preferably 50 to 80 ° C.

The stirring device 34 of the coagulation device 3 is configured to stir the magnesium salt aqueous solution filled in the stirring tank 30. Specifically, the stirring device 34 includes a motor 32 that generates rotational power and a stirring blade 33 that extends in a direction perpendicular to the rotation axis of the motor 32. The stirring blade 33 can flow the magnesium salt aqueous solution by rotating around the rotation axis by the rotational power of the motor 32 in the magnesium salt aqueous solution filled in the stirring tank 30. The shape and size of the stirring blade 33, the number of installations, and the like are not particularly limited.

The drive control unit of the solidifying device 3 is configured to control the rotational drive of the motor 32 of the stirring device 34 to set the rotation speed and the rotation speed of the stirring blade 33 of the stirring device 34 to predetermined values. The rotation of the stirring blade 33 is performed by the drive control unit so that the stirring number of the magnesium salt aqueous solution is usually in the range of 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm, and particularly preferably 400 to 800 rpm. Be controlled. The peripheral speed of the magnesium salt aqueous 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, and most preferably 2.5 m / s or more. The rotation of the stirring blade 33 is controlled by the drive control unit so as to be. Further, the drive control unit sets the upper limit of the peripheral speed of the magnesium salt aqueous solution to be 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. The rotation of the stirring blade 33 is controlled.

The cleaning device 4 shown in FIG. 1 is configured to perform the processing related to the cleaning step described above. As schematically shown 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 by the coagulation device 3 with a large amount of water and cleaning.

The heating unit 41 of the cleaning device 4 is configured to heat the inside of the cleaning tank 40. Further, 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 in the range of 40 ° C. or higher, preferably 40 to 100 ° C., more preferably 50 to 90 ° C., and most preferably 60 to 80 ° C. To.

The water-containing crumb washed by the washing device 4 is supplied to the screw type extruder 5 that performs the dehydration step and the drying step. At this time, it is preferable that the water-containing crumb after cleaning is 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 sieve, or the like can be used.

Further, when the water-containing crumb after cleaning 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 setting the temperature of the water used for washing in the washing device 4 to 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. The temperature of the hydrous crumb may be 40 ° C. or higher, preferably 60 ° C. or higher when it is conveyed from the cleaning device 4 to the screw type extruder 5. As a result, the dehydration step and the drying step, which are the subsequent steps, can be effectively performed, and the water content of the finally obtained dried rubber can be significantly reduced.

The screw type extruder 5 shown in FIG. 1 is configured to perform the processes related to the above-mentioned dehydration step and drying step. Although the screw type extruder 5 is shown as a suitable example in FIG. 1, a centrifuge, a squeezer, or the like may be used as the dehydrator for performing the treatment related to the dehydration step. A hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, or the like may be used as the dryer.

The screw type extruder 5 is configured to mold the dried rubber obtained through the dehydration step and the drying step into a predetermined shape and discharge it. Specifically, the screw type extruder 5 has a dehydration barrel portion 53 having a function as a dehydrator for dehydrating the hydrous crumb washed by the cleaning device 4, and a drying machine having a function as a dryer for drying the hydrous crumb. A barrel portion 54 is provided, and a die 59 having a molding function for forming a water-containing crumb is provided 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 for the screw type extruder 5 shown in FIG. With this screw type extruder 5, the above-mentioned dehydration / drying step can be suitably performed.

The screw type extruder 5 shown in FIG. 2 is a biaxial screw type extruder / dryer provided with 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 dry 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 composed of 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, a first drying barrel 54a, a second drying barrel 54b, a third drying barrel 54c, a fourth drying barrel 54d, and a fifth drying barrel 54e. , A sixth dry barrel 54f, a seventh dry barrel 54g, and an eighth dry barrel 54h.

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

Further, the screw type extruder 5 individually heats the barrels 52a to 52b, 53a to 53c, 54a to 54h, and determines the water content crumbs in the barrels 52a to 52b, 53a to 53c, 54a to 54h, respectively. It has a heating means (not shown) for heating to a temperature. The heating means includes a number corresponding to each barrel 52a to 52b, 53a to 53c, 54a to 54h. As such a heating means, for example, a configuration is adopted in which high-temperature steam is supplied from the steam supply means to the steam distribution jackets formed in the barrels 52a to 52b, 53a to 53c, 54a to 54h. It is not limited to this. Further, the screw type extruder 5 has a temperature control means (not shown) that controls a 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 that constitute each barrel portion 52, 53, 54 in the barrel unit 51 is not limited to the mode shown in FIG. 2, and the acrylic rubber to be dried is used. 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. The number of dehydration barrels installed in the dehydration barrel portion 53 is preferably, for example, 2 to 10, and more preferably 3 to 6, because dehydration of the water-containing crumb of the adhesive acrylic rubber can be efficiently performed. Further, the number of dry barrels installed in the dry barrel portion 54 is preferably, for example, 2 to 10, and more preferably 3 to 8.

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

Further, the rotation direction of the pair of screws may be the same direction or different directions, but from the viewpoint of self-cleaning performance, a type that rotates in the same direction is preferable. The screw shape of the pair of screws is not particularly limited as long as it is a shape required for each of the barrel portions 52, 53, 54, and is not particularly limited.

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

The dehydration barrel portion 53 is a region for separating and discharging a liquid (serum water) containing a coagulant or the like from the hydrous crumb.

The first to third dehydration barrels 53a to 53c constituting the dehydration barrel portion 53 have dehydration slits 56a, 56b, and 56c for discharging the water content of the hydrous crumb to the outside, respectively. A plurality of the dehydration slits 56a, 56b, 56c are formed in the dehydration barrels 53a to 53c, respectively.

The slit widths, that is, the openings of the dehydration slits 56a, 56b, and 56c may be appropriately selected according to the usage conditions, and are usually 0.01 to 5 mm, so that the water-containing crumbs are less damaged and the water-containing crumbs have little loss. From the viewpoint of efficient dehydration, it is preferably 0.1 to 1 mm, and more preferably 0.2 to 0.6 mm.

There are two ways to remove water from the water-containing crumbs in each of the dehydration barrels 53a to 53c of the dehydration barrel portion 53: a liquid removal from the dehydration slits 56a, 56b, 56c, and a vapor removal. .. In the dehydration barrel portion 53 of the present embodiment, the case where water is removed in liquid form is defined as wastewater, and the case where water is removed in vapor form is defined as exhaust steam.

The dehydration barrel portion 53 is suitable because the water content of the adhesive acrylic rubber can be efficiently reduced by combining drainage and exhaust steam. In the dehydration barrel portion 53, which of the first to third dehydration barrels 53a to 53c is used for drainage or exhaust steam may be appropriately set according to the purpose of use, but is usually manufactured. When reducing the amount of ash in the acrylic rubber, it is advisable to increase the number of dehydration barrels for draining. In that case, for example, as shown in FIG. 2, drainage is performed in the first and second dehydration barrels 53a and 53b on the upstream side, and steam is discharged in the third dehydration barrel 53c on the downstream side. Further, for example, when the dehydration barrel portion 53 has four dehydration barrels, for example, drainage may be performed by three dehydration barrels on the upstream side, and steam may be exhausted by one dehydration barrel on the downstream side. On the other hand, when reducing the water content, it is preferable to increase the number of dehydration barrels for exhausting steam.

As described in the above-mentioned dehydration / drying step, the set temperature of the dehydration barrel portion 53 is usually in the range of 60 to 150 ° C., preferably 70 to 140 ° C., more preferably 80 to 130 ° C., and is dehydrated in the drained state. The set temperature of the dehydration barrel to be dehydrated is usually 60 ° C. to 120 ° C., preferably 70 to 110 ° C., more preferably 80 to 100 ° C., and the set temperature of the dehydration barrel to be dehydrated in the exhausted steam state is usually 100 to 150 ° C. The temperature is preferably in the range of 105 to 140 ° C, more preferably 110 to 130 ° C.

The drying barrel portion 54 is a region for drying the hydrous crumb after dehydration under reduced pressure. Of the first to eighth dry barrels 54a to 54h constituting the dry barrel portion 54, the second dry barrel 54b, the fourth dry barrel 54d, the sixth dry barrel 54f, and the eighth dry barrel 54h are It has vent ports 58a, 58b, 58c, and 58d for degassing, respectively. Vent pipes (not shown) are connected to the vent ports 58a, 58b, 58c, and 58d, respectively.

Vacuum pumps (not shown) are connected to the ends of the vent pipes, and the operation of the vacuum pumps reduces the pressure inside the drying barrel portion 54 to a predetermined pressure. The screw type extruder 5 has a pressure control means (not shown) that controls the operation of these vacuum pumps to control the degree of decompression in the drying barrel portion 54.

The degree of decompression in the dry 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 dry barrels 54a to 54h constituting the dry barrel portion 54, the set temperatures in all the dry barrels 54a to 54h may be approximated or different, but on the upstream side (dehydrated barrel portion). It is preferable to set the temperature on the downstream side (die 59 side) to a higher temperature than the temperature on the downstream side (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 by the drying barrel portion 54 is extruded into a shape corresponding to a predetermined nozzle shape by passing through the discharge 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 wire mesh 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 from the feed port 55 to the supply barrel portion 52. 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 the pair of screws in the barrel unit 51. In the dehydration barrel portion 53, as described above, the water contained in the water-containing crumb is drained and exhausted from the dehydration slits 56a, 56b, 56c provided in the first to third dehydration barrels 53a to 53c, respectively. , The hydrous crumb is dehydrated.

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

By passing through the dry barrel portion 54 as described above, the hydrous 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 to form a sheet. It is extruded from the die 59 as a dry rubber.

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

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 amount of the acrylic rubber sheet can be efficiently reduced. From the point of view, it is preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

The extrusion amount (Q) of 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 to 8, and 4 to 6 is particularly preferable.

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

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

FIG. 3 shows the configuration of a transport type cooling device 60 suitable as the cooling device 6 shown in FIG. The transport 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 transporting the sheet-shaped dry rubber 10. By using this transport type cooling device 60, the sheet-shaped dry rubber discharged from the screw type extruder 5 can be suitably cooled.

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

The transport-type cooling device 60 sends cold air to the conveyor 61 that 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. 3 and the sheet-shaped dry rubber 10 on the conveyor 61. It has 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 to the downstream side (right side in FIG. 3) on the conveyor belt 64.

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

The length (length of the portion where the cooling air can be blown) L1 of the conveyor 61 and the cooling means 65 of the transport type cooling device 60 is not particularly limited, but is, for example, 10 to 100 m, preferably 20 to 50 m. .. Further, the transport speed of the sheet-shaped dry rubber 10 in the transport-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, more preferably 15 to 70 m / hr.

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

The transport type 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 conveyors 61. It may be configured to include the cooling means 65 of the above. In that case, the total length of each of the two or more conveyors 61 and the cooling means 65 may be within the above range.

The bale device 7 shown in FIG. 1 is configured to extrude from a screw type extruder 5 and further process a dry rubber cooled by the cooling device 6 to produce a bale which is a block. The weight and shape of the acrylic rubber bale produced by the bale-forming device 7 are not particularly limited, but for example, an acrylic rubber bale having a substantially rectangular parallelepiped shape of about 20 kg is produced.

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, the bale-forming device 7 arranged on the downstream side of the transport-type cooling device 60 shown in FIG. 3 may be provided with a cutting mechanism for cutting the sheet-shaped dry rubber 10. Specifically, the cutting mechanism of the bale device 7 continuously cuts the cooled sheet-shaped dry rubber 10 at predetermined intervals and processes it into a cut sheet-shaped dry rubber 16 having a predetermined size. It is configured as follows. By laminating a plurality of cut sheet-shaped dry rubbers 16 cut to a predetermined size by a cutting mechanism, an acrylic rubber veil in which the cut-sheet-shaped dry rubbers 16 are laminated can be manufactured.

When producing an acrylic rubber veil on 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 laminating the cut sheet-shaped 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 in more detail with reference to Examples and Comparative Examples. In addition, "part", "%" and "ratio" in each example are weight-based unless otherwise specified. Various characteristics were evaluated according to the following method.

[Monomer composition]
Regarding the monomer composition in acrylic rubber, the monomer composition of each monomer unit in acrylic rubber was confirmed by 1 H-NMR, and the activity of the reactive group remained in acrylic rubber and each reaction thereof. The sex group content was confirmed by the following test method.
The content ratio of each monomer unit in the acrylic rubber was calculated from the amount used in the polymerization reaction of each monomer and the polymerization conversion rate. Specifically, since the polymerization reaction was an emulsion polymerization reaction and the polymerization conversion rate was approximately 100% in which none of the unreacted monomers could be confirmed, the content ratio of each monomer unit was set to a single amount. 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 groups 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 group was calculated by dissolving an acrylic rubber sheet or acrylic rubber veil in methyl ethyl ketone, adding a specified amount of hydrochloric acid to react with the epoxy group, and titrating the remaining amount of hydrochloric acid with potassium hydroxide. ..
(3) The amount of chlorine was calculated by completely burning an acrylic rubber sheet or an acrylic rubber veil in a combustion flask, absorbing the generated chlorine in water, and titrating with silver nitrate.

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

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

[Molecular weight and molecular weight distribution]
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn and Mz / Mw) of the acrylic rubber are as follows: dimethylformamide as a solvent, lithium chloride 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 the GPC-MALS method using the added solution. Specifically, a multi-angle laser light scattering photometric meter (MALS) and a differential refractometer (RI) are incorporated into a GPC (Gel Permeation Chromatography) device, and the light scattering intensity and refraction of the molecular chain solution size-sorted by the GPC device are incorporated. The molecular weight of the solute and its content were sequentially calculated and obtained by measuring the rate difference with the elution time. The measurement conditions and measurement method by the GPC device are as follows.
Column: 2 TSKgel α-M (φ7.8 mm x 30 cm, manufactured by Tosoh Corporation)
Temperature: Column 40 ° C
Flow velocity: 0.8 ml / mm
Sample preparation: 5 ml of solvent was added to 10 mg of sample, and the mixture was gently stirred at room temperature (dissolution was visually observed). 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.).

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

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

[Water content]
The water content (%) of the acrylic rubber sheet or the acrylic rubber veil was measured according to the JIS K6230-1: Oven A (volatile matter measurement) method.

[PH]
The pH of the acrylic rubber sheet or acrylic rubber bale is determined by dissolving 6 g (± 0.05 g) of the acrylic rubber sheet or acrylic rubber bale in 100 g of tetrahydrofuran, adding 2.0 ml of distilled water and confirming that the mixture is completely dissolved. Measured with an electrode.

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

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

[Storing stability evaluation]
For the storage stability of the rubber sample, the rubber sample was placed in a constant temperature and humidity chamber (SH-222 manufactured by ESPEC) at 45 ° C. × 80% RH, and the rate of change in water content before and after the test for 7 days was calculated and compared. Evaluation was performed using an index with 2 as 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 for a dipping test, and calculating the volume change rate before and after dipping according to the following formula. Comparative Example 2 was evaluated with an index of 100 (the smaller the index, the better 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 container 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 dioxyethylene phosphate sodium salt 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. Next, the balance of the monomer emulsion, 0.00033 parts of ferrous sulfate, 0.264 parts of sodium ascorbate, and 0.22 parts of potassium persulfate were continuously added dropwise to 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., it was confirmed that the polymerization conversion rate reached approximately 100%, and hydroquinone as a polymerization terminator was added to carry out the polymerization reaction. It was stopped to obtain an emulsion polymerization solution.

Next, in a coagulation tank equipped with a thermometer and a stirrer, the mixture was heated to 80 ° C. and vigorously stirred at a stirring blade rotation speed of 600 rpm (peripheral speed 3.1 m / s) of the stirrer. The obtained emulsion polymer solution was heated to 80 ° C. and continuously added to coagulate the polymer in 350 parts (coagulation solution using magnesium sulfate as an agent) to coagulate the solidified acrylic rubber crumb. A solidified slurry containing water was obtained. Moisture was discharged from the solidified layer while filtering the crumbs from the obtained slurry to obtain a hydrous crumb.

194 parts of warm water (70 ° C.) was added to the coagulation tank in which the filtered hydrous crumbs remained, and the mixture was stirred for 15 minutes to wash the hydrous crumbs, and then water was discharged, and 194 parts of warm water (70 ° C.) was discharged again. Was added and stirred for 15 minutes to wash the hydrous crumb (total number of washings was 2). The water-containing crumb (cramm temperature 60 ° C.) after cleaning 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. Next, the sheet-shaped dry rubber was cooled at a cooling temperature of 200 ° C./hr by using a transport-type cooling device directly connected to the screw type extruder.

The screw type extruder used in the first embodiment has one supply barrel, three dehydration barrels (first to third dehydration barrels), and five drying barrels (first to fifth drying barrels). It is configured. The first dehydration barrel drains water, and the second and third dehydration barrels drain steam. The operating conditions of the screw type extruder are as follows.

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

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

Next, before the temperature of the acrylic rubber sheet (A) becomes 40 ° C. or lower, a plurality of cut acrylic rubber sheets (A) are laminated so as to form 20 parts (20 kg), and the acrylic rubber veil (A) is used. Got Reactive group content, ash content, ash component content, specific gravity, gel amount, pH, glass transition temperature (Tg), water content, molecular weight, molecular weight distribution, complex viscosity, Mooney of the obtained acrylic rubber veil (A) 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 in the first-stage mixing was transferred to a roll at 50 ° C., and the compounding agent B of "Formulation 1" was mixed and mixed (second-stage mixing) to obtain a rubber mixture.

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

[Example 2]
The monomer component is 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 is nonylphenylhexaoxyethylene phosphate sodium salt. Except for the change, the same procedure as in Example 1 was carried out to obtain an acrylic rubber sheet (B) and an acrylic rubber bale (B), and each characteristic (however, the compounding agent was changed to “formulation 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 for changing to an ethylene phosphate sodium salt, and each characteristic (however, the compounding agent was changed to "formulation 3") was obtained by obtaining an acrylic rubber sheet (C) and an acrylic rubber bale (C). 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 drainage is performed in the first and second dehydration barrels, and after drainage in the second dehydration barrel. Acrylic rubber sheet (D) and acrylic rubber bale (D) were obtained in the same manner as in Example 1 except that the water content of the water-containing crumb was changed to 20%, and each characteristic was evaluated. The results of the acrylic rubber sheet (D) are shown in Table 2.

[Example 5]
The monomer component is 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 is nonylphenyloxyhexa. Acrylic rubber sheet (E) and acrylic rubber bale (E) were produced in the same manner as in Example 4 except that they were changed to oxyethylene phosphate sodium salt, and each characteristic (however, the compounding agent was changed to "formulation 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. Acrylic rubber sheet (F) and acrylic rubber bale (F) were produced in the same manner as in Example 5 except for changing to an ester sodium salt, and each characteristic was evaluated. The results of the acrylic rubber sheet (F) are shown in Table 2.

[Comparative Example 1]
The emulsion polymer solution obtained by emulsion polymerization in the same manner as in Example 3 is stirred (100 rpm, peripheral speed 0.5 m / s), and a coagulation reaction is carried out by adding a 0.7% magnesium sulfate aqueous solution at 80 ° C. to this. The hydrous crumb was generated by stirring the produced hydrous crumb with 194 parts of warm water (70 ° C.) for 15 minutes, and the operation was repeated again, and then dried in a hot air dryer at 160 ° C. to obtain the water content. 0.4% by weight of crumb-shaped acrylic rubber (G) was obtained, each characteristic 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 sodium lauryl sulfate and 1.82 parts of polyoxyethylene dodecyl ether (molecular weight 1500), the coagulation solution was changed to 0.7% aqueous sodium sulfate solution, and the washing method was a coagulation reaction. To 100 parts of the subsequent hydrous crumb, 194 parts of industrial water was added, and the mixture was stirred in the coagulation tank at 25 ° C. for 5 minutes, and then the hydrous crumb for discharging water from the coagulation tank was washed 4 times, and then at pH 3. After adding 194 parts of an aqueous sulfuric acid solution and stirring at 25 ° C. for 5 minutes, water is discharged from the coagulation tank to perform acid cleaning once, and then 194 parts of pure water is added to perform pure water cleaning once. Except for the change, the same procedure as in Comparative Example 1 was carried out to obtain a crumb-shaped acrylic rubber (H) and evaluate each characteristic. The results are shown in Table 2.

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

From Table 2, the amount of ash is determined by using a divalent phosphoric acid-based emulsifier and divalent magnesium as compared with the crumb-like acrylic rubber (H) which was coagulated with a monovalent sodium salt using a sulfuric acid-based emulsifier and washed and dried. It can be seen that the amount of crumb-shaped acrylic rubber (G) solidified with salt, washed and dried is overwhelmingly large (comparison between Comparative Examples 1 and 2).

However, by specifying the coagulant concentration and addition method in the coagulation step, the rotation speed and peripheral speed of the coagulation liquid, and by dehydrating and squeezing out the components that become ash together with water from the hydrous crumb, the acrylic rubber sheet (A) It can be seen that the amount of ash in (F) could be reduced (comparison between Examples 1 to 6 and Comparative Example 1). In addition. The ash content of the acrylic rubber sheets (A) to (F) is reduced to only 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 characteristics are overwhelmingly improved, with ~ 1/10 and water resistance of 1/10 to 1/50. This is because the ratio of the amount of phosphorus to the amount of magnesium in the ash increases, and the ratio of magnesium to phosphorus (Mg / P) becomes a specific range, which gives an overwhelming effect of improving storage stability and water resistance. ..

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

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

According to the present invention, a monomer component containing (meth) acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid-based emulsifier and emulsion-polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization solution. A polymerization step, a coagulation step of bringing the obtained emulsion polymerization solution into contact with a magnesium salt aqueous solution as a coagulant to generate a hydrous crumb, a cleaning step of washing the produced hydrous crumb, and a dehydration slit of the washed hydrous crumb. Using a dehydration barrel, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip, the dehydration barrel is dehydrated to a water content of 1 to 40% by weight, and then dried to less than 1% by weight in a drying barrel. Provided is a method for producing an acrylic rubber sheet, which includes a dehydration / drying / molding step of extruding a dry rubber from a die.

(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 (meth) acrylic acid ester as a main component is emulsified with water and a divalent phosphoric acid-based emulsifier, and emulsified in the presence of a polymerization catalyst. It is characterized by polymerizing to obtain an emulsion polymerization solution.

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

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

Claims (22)

It is composed of acrylic rubber having a weight average molecular weight (Mw) of 100,000 to 5,000,000, which is mainly composed of (meth) acrylic acid ester, has an ash content of 0.8% by weight or less, and magnesium and phosphorus in the ash content. The total amount of acrylic is 30% by weight or more as a ratio to the total ash content, and the ratio of magnesium to phosphorus ([Mg] / [P]) is in the range of 0.4 to 2.5 by weight. Rubber sheet. 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 optionally a copolymer. The acrylic rubber sheet according to claim 1, which is formed from other polymerizable monomers. The acrylic rubber sheet according to claim 1 or 2, wherein the complex viscosity at 60 ° C. ([η] 60 ° C.) is 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) to 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, which has a specific gravity in the range of 0.7 to 1.5. The acrylic rubber sheet according to any one of claims 1 to 5, wherein the amount of gel is 50% by weight or less. The acrylic rubber sheet according to any one of claims 1 to 6, which has a pH of 6 or less. The acrylic rubber sheet according to any one of claims 1 to 7, wherein the glass transition temperature (Tg) is 20 ° C. or lower. The acrylic rubber sheet according to any one of claims 1 to 8, wherein the Mooney viscosity (ML1 + 4,100 ° C.) is in the range of 10 to 150. An emulsion polymerization step of emulsifying a metric component containing (meth) acrylic acid ester as a main component with water and a divalent phosphoric acid emulsifier and emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization solution.
A coagulation step in which the obtained emulsion polymerization solution is brought into contact with an aqueous magnesium salt solution as a coagulant to form a hydrous crumb,
A cleaning process to clean the generated hydrous crumbs,
The washed water-containing crumb is 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, and then in a drying barrel 1 Dehydration / drying / molding process that dries to less than% by weight and extrudes sheet-shaped dry rubber from the die.
A method of manufacturing an acrylic rubber sheet including. The method for producing an acrylic rubber sheet according to claim 10, wherein the contact between the emulsion polymerization solution and the magnesium salt aqueous solution is performed by adding the emulsion polymerization solution to the stirred magnesium salt aqueous solution. The method for producing an acrylic rubber sheet according to claim 11, wherein the rotation speed of the stirred magnesium salt aqueous solution is 100 rpm or more. The method for producing an acrylic rubber sheet according to claim 11 or 12, wherein the stirring magnesium salt aqueous solution has a peripheral speed of 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 rotation speed (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 the extrusion amount (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 portion 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 decompression of the drying barrel portion 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 portion 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 a reinforcing agent and a cross-linking agent with the acrylic rubber sheet according to any one of claims 1 to 9 or the acrylic rubber veil according to claim 20. A rubber crosslinked product obtained by cross-linking the rubber mixture according to claim 21.