JP7452264B2 - Acrylic rubber sheet with excellent workability - Google Patents

Description

The present invention relates to an acrylic rubber sheet, a method for producing an acrylic rubber sheet, an acrylic rubber veil, a rubber mixture, and a crosslinked rubber product. The present invention relates to an acrylic rubber veil formed by laminating acrylic rubber sheets, a rubber mixture formed by mixing the acrylic rubber sheets or acrylic rubber veils, a method for producing the same, and a crosslinked rubber product obtained by crosslinking the same.

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

Such acrylic rubber is usually produced by emulsion polymerizing the monomer mixture that makes up the acrylic rubber, adding a coagulant to the resulting emulsion polymerization solution, and then drying the resulting water-containing crumb. It is then commercialized in the form of crumbs, sheets, or bales.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 1-225512), a twin-screw extrusion dryer consisting of a feed barrel, a dehydration barrel, a standard barrel, a vent barrel, and a vacuum barrel is used to produce nitrile with a water content of about 50%. Rubber (NBR) crumb is supplied to the feed barrel, and after dehydrating most of the moisture in the dehydration barrel, the remaining moisture and evaporated substances are removed by suction in the vacuum barrel, and it is continuously extruded into a strip through the breaker plate and die section. A method for manufacturing sheet-like acrylic rubber is disclosed. It is also described that a rubber crumb such as acrylic rubber is used as the applicable rubber crumb. However, Patent Document 1 does not describe an acrylic rubber sheet that has excellent processability.

On the other hand, regarding veil-shaped acrylic rubber, for example, Patent Document 2 (International Publication No. 2018/116828 pamphlet) describes monomer components consisting of ethyl acrylate, n-butyl acrylate, and mono-n-butyl fumarate. Acrylic rubber latex is emulsified with water, sodium lauryl sulfate as an emulsifier, and polyethylene glycol monostearate, and emulsion polymerized in the presence of a polymerization initiator until a polymerization conversion rate of 95% is reached. After adding it to an aqueous solution of amine-ammonia-epichlorohydrin polycondensate, it was stirred at 85°C to produce a crumb slurry, and then the crumb slurry was washed once with water and passed through a 100-mesh wire gauze in its entirety to form a solid. A method for recovering crumb-like acrylic rubber by supplementing only the amount is disclosed. According to this method, the obtained water-containing crumb is dehydrated by centrifugation, etc., dried at 50 to 120°C using a band dryer, etc., and is introduced into a baler to be compressed and made into a product. There is. However, in this method, a large number of semi-solidified hydrous crumbs are generated during the coagulation reaction, and there are problems in that a large amount of them adhere to the coagulation tank and that even if the sticky crumbs are dried and made into a veil, processability is poor.

Regarding the gel amount of acrylic rubber, for example, Patent Document 3 (Japanese Patent No. 3,599,962) discloses that two radically reactive unsaturated groups having different reactivity with 95 to 99.9% by weight of alkyl acrylate or alkoxyalkyl acrylate are used. Acrylic rubber with a gel fraction of acetone-insoluble matter of 5% by weight or less obtained by copolymerizing 0.1 to 5% by weight of the above polymerizable monomer in the presence of a radical polymerization initiator, reinforcing properties An acrylic rubber composition comprising a filler and an organic peroxide-based vulcanizing agent and having excellent extrusion processability such as extrusion speed, die swell, and surface texture is disclosed. The acrylic rubber with a very low gel fraction used here is different from the acrylic rubber with a high gel fraction (60%) obtained when the polymerization solution is in a normal acidic range (pH 4 before polymerization, pH 3.4 after polymerization). On the other hand, it is obtained by adjusting the pH of the polymerization solution to 6 to 8 with sodium hydrogen carbonate or the like. Specifically, water, sodium lauryl sulfate as an emulsifier, polyoxyethylene nonylphenyl ether, sodium carbonate, and boric acid were charged and the temperature was adjusted to 75°C, and then t-butyl hydroperoxide, Rongalite, disodium ethylenediaminetetraacetate, Ferrous sulfate was added (pH at this time was 7.1), and then the monomer components of ethyl acrylate and allyl methacrylate were added dropwise to perform emulsion polymerization, and the resulting emulsion (pH 7) was added to an aqueous sodium sulfate solution. Acrylic rubber is obtained by salting out, washing with water, and drying. However, acrylic rubber whose main component is (meth)acrylic acid ester has problems in handling, such as decomposition in the neutral to alkaline range and poor storage stability. The acrylic rubber used had a problem with poor mechanical strength due to the loss of reactive groups (crosslinking points) such as carboxyl groups, epoxy groups, and chlorine atoms.

In addition, in Patent Document 4 (International Publication No. 2018/143101 pamphlet), a (meth)acrylic acid ester and an ionic crosslinkable monomer are emulsion polymerized, and the complex viscosity at 100°C ([η] 100°C) is is 3,500 Pa・s or less, and the ratio of the complex viscosity at 60°C ([η]60°C) to the complex viscosity at 100°C ([η]100°C) ([η]100°C/[η]60 A technique has been disclosed for improving the extrusion moldability of a rubber composition containing a reinforcing agent and a crosslinking agent, particularly the extrusion amount, extrusion length, and surface texture using an acrylic rubber having a temperature of 0.8 or less. The amount of gel insoluble in THF (tetrahydrofuran) in the acrylic rubber used in the same technology is 80% by weight or less, preferably 5 to 80% by weight, and it is preferable that the gel content is as much as possible within the range of 70% or less. Preferably, it is stated that when the gel amount is less than 5%, extrudability deteriorates. In addition, the weight average molecular weight (Mw) of the acrylic rubber used is 200,000 to 1,000,000, and when the weight average molecular weight (Mw) exceeds 1,000,000, the viscoelasticity of the acrylic rubber is high. There are descriptions of things that are too undesirable. However, there is a growing demand for a material that is highly balanced in workability, processability, and strength properties.

Japanese Patent Application Publication No. 1-225512 International Publication No. 2018/116828 pamphlet Patent No. 3599962 International Publication No. 2018/143101 pamphlet

The present invention has been made in view of the above circumstances, and provides an acrylic rubber sheet with excellent workability, processability, and strength properties, a method for producing the same, an acrylic rubber veil formed by laminating the acrylic rubber sheet, and an acrylic rubber sheet formed by laminating the acrylic rubber sheet. The object of the present invention is to provide a rubber mixture containing a rubber sheet or an acrylic rubber veil, and a crosslinked rubber product thereof.

As a result of intensive research in view of the above problems, the present inventors have found that an acrylic rubber sheet made of acrylic rubber with a specific molecular weight containing (meth)acrylic acid ester as the main component and having a specific amount of gel insoluble in methyl ethyl ketone has improved workability and processability. It was found that the material has excellent properties of strength and strength. The inventors have also found that the effectiveness of the invention is further improved at specific pH and water content.

The present inventors also produced a sheet by drying hydrous crumb produced by emulsion polymerization and coagulation of a monomer component mainly composed of (meth)acrylic acid ester to a specific water content using a specific screw extruder. We have discovered that an acrylic rubber sheet with excellent workability, processability, and strength properties can be easily produced by extruding it as a dry rubber.

The present inventors also found that in order to improve the strength properties of acrylic rubber containing (meth)acrylic acid ester as a main component, when the polymerization conversion rate of emulsion polymerization was increased to a specific polymerization conversion rate, the gel amount rapidly increased and the processability improved. However, by drying the washed water-containing crumb using a screw extruder until it contains virtually no water (specific water content) and then melting and kneading it, the rapidly increased amount of gel disappears and the reactivity is reduced. We have discovered that it is possible to produce an acrylic rubber sheet with highly excellent workability, processability, and strength properties without reducing the number of groups.

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

Thus , according to the present invention, the monomer composition is a bonding unit 70 derived from at least one (meth)acrylic acid ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester. -99.9% by weight, 0.01-20% by weight of bonding units derived from reactive group-containing monomers, and 0-30% by weight of bonding units derived from other monomers, on a weight average Made of acrylic rubber having a molecular weight (Mw) of 1,000,000 to 5,000,000 and a ratio of z average molecular weight (Mz) to weight average molecular weight (Mw) (Mz/MW) of 1.3 or more , An acrylic rubber sheet is provided that has an ash content of 1% by weight or less, a water content of less than 1% by weight, a pH of 6 or less, and a gel content of methyl ethyl ketone insoluble matter of 10 % by weight or less.

In the acrylic rubber sheet of the present invention, the amount of acrylic rubber in the acrylic rubber sheet is preferably 95% by weight or more.

In the acrylic rubber sheet of the present invention, it is preferable that the reactive group-containing monomer has at least one functional group selected from the group consisting of a carboxyl group, an epoxy group, and a halogen group .

In the acrylic rubber sheet of the present invention, the content of at least one element selected from the group consisting of sodium, sulfur, calcium, magnesium, and phosphorus in the ash is preferably 50% by weight or more.

In the acrylic rubber sheet of the present invention, it is preferable that the acrylic rubber sheet is a melt-kneaded sheet.

In the acrylic rubber sheet of the present invention, it is preferable that the amount of gel insoluble in methyl ethyl ketone is 5 % by weight or less.

The acrylic rubber sheet of the present invention is made of an acrylic rubber having the above composition and the ratio of the weight average molecular weight (Mw) and the z average molecular weight (Mz) to the weight average molecular weight (Mw) (Mz/MW), respectively, within the above ranges. In addition, by satisfying the above conditions for the ash content, water content, pH, and gel content of insoluble methyl ethyl ketone, it not only has highly excellent workability, processability, and strength properties, but also has other properties as well. It becomes a good acrylic rubber sheet .

According to the present invention, 70 to 99.9% by weight of at least one (meth)acrylic ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester; A monomer component consisting of 0.01 to 20% by weight of a group-containing monomer and 0 to 30% by weight of bonding units derived from other monomers is emulsified with water and an emulsifier, and then polymerized in the presence of a polymerization catalyst. An emulsion polymerization step in which an emulsion polymerization solution is obtained by emulsion polymerization to a ratio of 90% by weight or more, a coagulation step in which the obtained emulsion polymerization solution is added to a coagulation solution being stirred to produce a hydrous crumb, and a coagulation step in which a hydrous crumb is produced. and the washed water-containing crumb is reduced 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 with a die at the tip. %, then drying in the drying barrel to a water content of less than 1% by weight , and extruding the melt-kneaded sheet-like dried rubber from a die. .
In the method for producing an acrylic rubber sheet of the present invention, it is preferable to use an emulsifier containing a phosphate ester salt as an emulsifier in the emulsion polymerization step.
In the method for producing an acrylic rubber sheet of the present invention, it is preferable to use an aqueous solution of an alkali metal salt or a Group 2 metal salt of the periodic table as the coagulation liquid in the coagulation step.

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

According to the present invention, there is provided a rubber mixture obtained by mixing the acrylic rubber sheet or the acrylic rubber veil described above with a reinforcing agent and a crosslinking agent.

Furthermore, according to the present invention, a crosslinked rubber product obtained by crosslinking the rubber mixture is provided.

According to the present invention, an acrylic rubber sheet with excellent workability, processability and strength properties, a method for producing the same, an acrylic rubber veil formed by laminating the acrylic rubber sheet, and a mixture of the acrylic rubber sheet or the acrylic rubber veil. A rubber mixture and a crosslinked rubber product obtained by crosslinking the same are provided.

1 is a diagram schematically showing an example of an acrylic rubber manufacturing system used for manufacturing an acrylic rubber sheet according to an embodiment of the present invention. 2 is a diagram showing the configuration of the screw type extruder of FIG. 1. FIG. FIG. 2 is a diagram showing the configuration of a transport type cooling device used as the cooling device of FIG. 1. FIG.

The acrylic rubber sheet of the present invention is made of acrylic rubber whose main component is (meth)acrylic ester and has a weight average molecular weight (Mw) of 1,000,000 to 5,000,000, and has a gel content of 50% by weight or less. It is characterized by

<Monomer component>
The acrylic rubber constituting the acrylic rubber sheet of the present invention has (meth)acrylic acid ester as a main component. The proportion of (meth)acrylic acid ester in the acrylic rubber is appropriately selected depending on the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more.

The acrylic rubber constituting the acrylic rubber sheet of the present invention contains at least one (meth)acrylic ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester. It is preferable that the crosslinked properties of the rubber sheet can be highly improved.

The acrylic rubber constituting the acrylic rubber sheet of the present invention is preferably one containing a reactive group-containing monomer because it can highly improve heat resistance, compression set resistance, and the like.

Preferred specific examples of the acrylic rubber constituting the acrylic rubber sheet of the present invention include at least one (meth)acrylic ester selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid alkoxyalkyl esters. , a reactive group-containing monomer, and, if necessary, other copolymerizable monomers.

There are no particular limitations on the (meth)acrylic acid alkyl ester, but it usually has a (meth)acrylic acid alkyl group having 1 to 12 carbon atoms, preferably a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms. ) Acrylic acid alkyl esters, more preferably (meth)acrylic acid alkyl esters having an alkyl group having 2 to 6 carbon atoms.

Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and n-(meth)acrylate. Examples include butyl, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and ethyl (meth)acrylate, (meth)acrylate. N-butyl is preferred, and ethyl acrylate and n-butyl acrylate are more preferred.

There are no particular limitations on the (meth)acrylic acid alkoxyalkyl ester, but the (meth)acrylic acid alkoxyalkyl ester usually has 2 to 12 alkoxyalkyl groups, preferably has 2 to 8 alkoxyalkyl groups. ) Acrylic acid alkoxyalkyl ester, more preferably (meth)acrylic acid alkoxy ester having an alkoxyalkyl group having 2 to 6 carbon atoms.

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

At least one (meth)acrylic ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester is used alone or in combination of two or more, and 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, most preferably 87 to 99% by weight. If the amount of (meth)acrylic acid ester in the monomer component is too small, the resulting acrylic rubber sheet may have poor weather resistance, heat resistance, and oil resistance, which is not preferable.

The reactive group-containing monomer is not particularly limited and is appropriately selected depending on the purpose of use, but monomers having at least one functional group selected from the group consisting of carboxyl group, epoxy group, and halogen group. A monomer having at least one functional group selected from the group consisting of a carboxyl group, an epoxy group and a chlorine atom is more preferable, and a monomer having an ionic crosslinkable group such as a carboxyl group and an epoxy group is preferable. Particularly preferred are monomers having a carboxyl group, most preferred.

Although there are no particular limitations on the monomer having a carboxyl group, ethylenically unsaturated carboxylic acids can be suitably used. Examples of ethylenically unsaturated carboxylic acids include ethylenically unsaturated monocarboxylic acids, ethylenically unsaturated dicarboxylic acids, and ethylenically unsaturated dicarboxylic acid monoesters. Ester is preferable because it can further improve the compression set resistance when the acrylic rubber sheet is crosslinked with rubber.

The ethylenically unsaturated monocarboxylic acid is not particularly limited, but is preferably an ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms, such as acrylic acid, methacrylic acid, α-ethyl acrylic acid, crotonic acid, Examples include cinnamic acid.

The ethylenically unsaturated dicarboxylic acid is not particularly limited, but is preferably an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms, such as fumaric acid, butenedionic acid such as maleic acid, itaconic acid, citraconic acid, etc. can be mentioned. Note that ethylenically unsaturated dicarboxylic acids include those existing as anhydrides.

The ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, but it 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 6 carbon atoms. An ethylenically unsaturated dicarboxylic acid and an alkyl monoester having 2 to 8 carbon atoms, more preferably an alkyl monoester having 2 to 6 carbon atoms of butenedic acid having 4 carbon atoms.

Specific examples of ethylenically unsaturated dicarboxylic acid monoesters include monomethyl fumarate, monoethyl fumarate, mono-n-butyl fumarate, monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monocyclopentyl fumarate, and fumarate. Butenedionic acid monoalkyl esters such as monocyclohexyl acid, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate; itaconic acid such as monomethyl itaconate, monoethyl itaconate, mono n-butyl itaconate, monocyclohexyl itaconate Among these, mono-n-butyl fumarate and mono-n-butyl maleate are preferred, and mono-n-butyl fumarate is particularly preferred.

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

Examples of monomers having 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 acid (haloacetylcarbamoyl esters). Examples include oxy)alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers.

Examples of the unsaturated alcohol ester of a halogen-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, allyl chloroacetate, and the like. Examples of the (meth)acrylic acid haloalkyl ester include chloromethyl (meth)acrylate, 1-chloroethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 1,2-dichloroethyl (meth)acrylate, Examples include 2-chloropropyl (meth)acrylate, 3-chloropropyl (meth)acrylate, and 2,3-dichloropropyl (meth)acrylate. Examples of the (meth)acrylic acid haloacyloxyalkyl ester include 2-(chloroacetoxy)ethyl (meth)acrylate, 2-(chloroacetoxy)propyl (meth)acrylate, and 3-(chloroacetoxy)(meth)acrylate. ) propyl, 3-(hydroxychloroacetoxy)propyl (meth)acrylate, and the like. Examples of the (meth)acrylic acid (haloacetylcarbamoyloxy)alkyl ester include 2-(chloroacetylcarbamoyloxy)ethyl (meth)acrylate and 3-(chloroacetylcarbamoyloxy)propyl (meth)acrylate. It will be done. Examples of the halogen-containing unsaturated ether include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, and 3-chloropropyl allyl ether. Examples of the halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, and 2-chloroethyl allyl ketone. Examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl-α-methylstyrene. Examples of the halogen-containing unsaturated amide include N-chloromethyl (meth)acrylamide. Examples of the haloacetyl group-containing unsaturated monomer include 3-(hydroxychloroacetoxy)propyl allyl ether and p-vinylbenzylchloroacetate.

These reactive group-containing monomers are used alone or in combination of two or more, and their proportion in the acrylic rubber is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight. , more preferably 0.5 to 5% by weight, most preferably 1 to 3% by weight.

Other monomers that may be used as necessary are not particularly limited as long as they can be copolymerized with the above monomers, such as aromatic vinyl, ethylenically unsaturated nitriles, acrylamide monomers, and others. Examples include olefinic monomers. Examples of the aromatic vinyl include styrene, α-methylstyrene, and divinylbenzene. Examples of ethylenically unsaturated nitriles include acrylonitrile and methacrylonitrile. Examples of the acrylamide monomer include acrylamide and methacrylamide. Examples of other olefinic monomers include ethylene, propylene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, and the like.

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

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

The reactive group is not particularly limited and is appropriately selected depending on the purpose of use, 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. The crosslinking properties of the acrylic rubber sheet can be highly improved when the functional group is at least one kind of functional group selected from the group consisting of chlorine, epoxy, and chlorine atoms, particularly preferably carboxyl and epoxy groups, and most preferably carboxyl. It is. Further, as the reactive group, an ion-reactive group such as a carboxyl group or an epoxy group is preferable since it can particularly improve water resistance. As for the acrylic rubber having such a reactive group, a reactive group may be added to the acrylic rubber through a post-reaction, but preferably one obtained by copolymerizing a reactive group-containing monomer is suitable.

The content of the reactive group may be appropriately selected depending on the purpose of use, but the weight percentage of the reactive group itself is usually 0.001 or more, preferably 0.001 to 5% by weight, more preferably 0. Processability, strength properties, compression set resistance, oil resistance, It is suitable because its properties 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 ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester; Consisting of a reactive group-containing monomer and other copolymerizable monomers as necessary, the proportions of each in the acrylic rubber are (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester. The bonding unit derived from at least one (meth)acrylic acid ester selected from the group consisting of usually 50% by weight or more, preferably 70 to 99.9% by weight, more preferably 80 to 99.5% by weight, especially It is preferably in the range of 87 to 99% by weight, and the bonding unit derived from the reactive group-containing monomer is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5% by weight. -5% by weight, particularly preferably 1-3% by weight, and the bonding units derived from other monomers are usually 0-30% by weight, preferably 0-20% by weight, more preferably 0-15% by weight. % by weight, particularly preferably in the range from 0 to 10% by weight. By setting the bonding units derived from these monomers in the acrylic rubber within this range, the objects of the present invention can be achieved to a high degree, and when the acrylic rubber sheet is made into a crosslinked product, the water resistance and compression set resistance properties are significantly improved. Improved and suitable.

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, and is 1,000,000 to 5,000,000, preferably 1,100,000. 4,000,000, more preferably 1,200,000 to 2,500,000, the workability, processability, strength characteristics, and compression set resistance of the acrylic rubber sheet during mixing are within the range of Highly balanced and suitable.

The ratio (Mz/Mw) between 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 an absolute value with emphasis on the high molecular weight region measured by GPC-MALS. When the molecular weight distribution is 1.3 or more, preferably 1.4 to 5, more preferably 1.5 to 2, the workability, processability, and strength characteristics of the acrylic rubber sheet are highly balanced and preserved. This is preferable because it can alleviate changes in physical properties over time.

The glass transition temperature (Tg) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is not particularly limited, but is usually 20°C or lower, preferably 10°C or lower, and more preferably 0°C or lower. 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 at or above the above-mentioned lower limit, it is possible to obtain better oil resistance and heat resistance, and by setting the glass transition temperature at or below the above-mentioned upper limit, it is possible to obtain more excellent cold resistance and processability.

The content of acrylic rubber in the acrylic rubber sheet of the present invention is appropriately selected depending on the purpose of use, but is usually 95% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more.

<Acrylic rubber sheet>
The acrylic rubber sheet of the present invention is characterized by being made of the above acrylic rubber and having a specific amount of gel.

The thickness of the acrylic rubber sheet of the present invention is not particularly limited, but it is generally 1 to 40 mm, preferably 2 to 35 mm, more preferably 3 to 30 mm, and most preferably 5 to 25 mm for workability. , storage stability and productivity are highly balanced and suitable. In particular, when manufacturing an acrylic rubber sheet that significantly improves productivity and is inexpensive, the thickness is usually in the range of 1 to 30 mm, preferably 2 to 25 mm, more preferably 3 to 15 mm, particularly preferably 4 to 12 mm.

The width of the acrylic rubber sheet of the present invention is appropriately selected depending on the purpose of use, but a range of usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm is particularly suitable for excellent workability. It is.

Although the length of the acrylic rubber sheet of the present invention is not particularly limited, a range of usually 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm is particularly suitable for excellent workability. be.

The amount of gel in the acrylic rubber sheet of the present invention is 50% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, based on the insoluble content of methyl ethyl ketone. When it is less than % by weight, processability is highly improved and it is preferable. The amount of gel, which is the insoluble content of methyl ethyl ketone in the acrylic rubber veil, is related to the processability during kneading such as Banbury, but the characteristics of the amount of gel vary depending on the solvent used, especially when THF (tetrahydrofuran) is insoluble. There was no correlation with the amount of gel.

The specific gravity of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 0.7 or more, preferably 0.8 to 1.4, more preferably 0.9 to 1.3, particularly preferably 0.95 to 1.25, most preferably in the range of 1.0 to 1.2, as storage stability is highly excellent and 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, particularly preferably 3 to 5. Storage stability is highly improved and suitable.

Although the moisture content of the acrylic rubber sheet of the present invention is not particularly limited, it is usually less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less, and has crosslinking properties. is optimized and has highly excellent properties such as heat resistance and water resistance, making it suitable.

The ash content of the acrylic rubber sheet of the present invention is. Although not particularly limited, it is usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.3% by weight or less, particularly preferably 0.2% by weight or less, most preferably 0.15% by weight or less. When it is less than % by weight, it is suitable because it 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 usually 0.0001% by weight or more, preferably 0.0005% by weight or more, more preferably 0.001% by weight or more, Particularly preferably, the content is 0.005% by weight or more, and most preferably 0.01% by weight or more, since metal adhesion is suppressed and workability is excellent.

The content of at least one element selected from the group consisting of sodium, sulfur, calcium, magnesium, and phosphorus in the ash of the acrylic rubber sheet of the present invention is not particularly limited, but is usually expressed as a percentage of the total ash content. When the content is at least 30% by weight, preferably 50% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, storage stability and water resistance are excellent.

The total amount of sodium and sulfur in the ash of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight relative to the total ash content. % or more, particularly preferably 80% by weight or more, since storage stability and water resistance are highly excellent.

The ratio of sodium to sulfur ([Na]/[S]) in the ash of the acrylic rubber sheet of the present invention is usually 0.4 to 2.5, preferably 0, although there is no particular limitation in terms of weight ratio. A range of 0.6 to 2, preferably 0.8 to 1.7, more preferably 1 to 1.5 is preferable because the water resistance is highly excellent.

The total amount of magnesium and phosphorus in the ash of the acrylic rubber sheet of the present invention is not particularly limited, but is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight based on the total ash content. % or more, particularly preferably 80% by weight or more, since storage stability and water resistance are highly excellent.

The ratio of magnesium to phosphorus ([Mg]/[P]) in the ash of the acrylic rubber sheet of the present invention is a weight ratio, and there is no particular limitation, but it is usually 0.4 to 2.5, preferably 0. Storage stability and water resistance are within the range of .4 to 1.3, more preferably 0.4 to 1, particularly preferably 0.45 to 0.75, and most preferably 0.5 to 0.7. Highly excellent and 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 in the range of 2,500 to 7,000 Pa·s, most preferably in the range of 2,700 to 5,500 Pa·s, which is suitable for excellent workability, oil resistance and shape retention.

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

The ratio of the complex viscosity at 100°C ([η] 100°C) and the complex viscosity at 60°C ([η] 60°C) of the acrylic rubber sheet of the present invention ([η] 100°C/[η] 60°C) Although not particularly limited, is usually 0.5 or more, preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, and most preferably 0.83 or more. Further, the ratio ([η] 100°C/[η] 60°C) between the complex viscosity at 100°C ([η] 100°C) and the complex viscosity at 60°C ([η] 60°C) is usually 0. 5 to 0.99, preferably 0.6 to 0.98, more preferably 0.75 to 0.95, particularly preferably 0.8 to 0.94, most preferably 0.83 to 0.93. It is preferable that the processability, oil resistance, and shape retention are highly balanced.

The Mooney viscosity (ML1+4, 100°C) of the acrylic rubber sheet of the present invention is not particularly limited, but is usually in the range of 10 to 150, preferably 20 to 100, more preferably 25 to 70 when processed. It is suitable because its properties and strength properties are highly balanced.
The types of acrylic rubber sheets of the present invention are not particularly limited, but include, for example, blown sheets made by blow molding, cast sheets made by solution casting, and melt-kneaded sheets made by melt extrusion. Among these, melt-kneaded sheets are preferred because they can maximize storage stability effects.
<Method for manufacturing acrylic rubber sheet>
The method for producing the acrylic rubber sheet of the present invention is not particularly limited, but may include, for example, emulsifying a monomer component containing (meth)acrylic acid ester as a main component with water and an emulsifier in the presence of a polymerization catalyst. an emulsion polymerization step of obtaining an emulsion polymerization solution by carrying out emulsion polymerization to a polymerization conversion rate of 90% by weight or more;
a coagulation step of bringing the obtained emulsion polymerization liquid into contact with a coagulation liquid to produce water-containing crumb;
a cleaning step of cleaning the generated water-containing crumb;
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 die at the tip, and then impregnated in a drying barrel. A dehydration, drying, and molding step of drying the water content to less than 1% by weight and extruding the sheet-like dry rubber from a die;
The acrylic rubber sheet of the present invention can be easily manufactured by including the following.

(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 an emulsifier, and the polymerization conversion rate is 90% by weight or more in the presence of a polymerization catalyst. The emulsion polymerization solution is emulsified with water and an emulsifier, and then emulsion polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization solution.

The monomer components used are the same as those described for the monomer components, and the amount used is appropriately selected so as to achieve the monomer composition of the acrylic rubber constituting the acrylic rubber sheet. Usually, the amount is the same as the monomer composition of the acrylic rubber constituting the acrylic rubber sheet.

The emulsifier to be used is not particularly limited, but examples include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, etc., preferably those containing anionic emulsifiers, and particularly preferably sulfuric esters. It includes a salt, a phosphate ester salt, and most preferably a phosphate ester salt.

There are no particular limitations on the anionic emulsifier; for example, salts of fatty acids such as myristic acid, palmitic acid, oleic acid, and linolenic acid; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; sulfuric esters such as sodium lauryl sulfate. Salts, phosphate ester salts such as polyoxyalkylene alkyl ether phosphate ester salts; alkyl sulfosuccinates, and the like. Among these anionic emulsifiers, phosphate ester salts and sulfate ester salts are preferred, and phosphate ester salts are particularly preferred. These anionic emulsifiers can be used alone or in combination of two or more.

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

Nonionic emulsifiers are not particularly limited, but include, for example, polyoxyalkylene fatty acid esters such as polyoxyethylene stearate; polyoxyalkylene alkyl ethers such as polyoxyethylene dodecyl ether; and polyoxylic acids such as polyoxyethylene nonylphenyl ether. Alkylene alkyl phenol ether; examples include polyoxyethylene sorbitan alkyl ester, polyoxyalkylene alkyl ether and polyoxyalkylene alkyl phenol ether are preferred, and polyoxyethylene alkyl ether and polyoxyethylene alkyl phenol ether are more preferred.

These 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, preferably 0.01 to 10 parts by weight, based on 100 parts by weight of the monomer component. It ranges from 1 to 5 parts by weight, more preferably from 1 to 3 parts by weight.

The monomer component, water, and emulsifier may be mixed by a conventional method, and examples include a method of stirring the monomer, emulsifier, and water using a stirrer such as a homogenizer or a disk turbine. . The amount of water used is usually 10 to 750 parts by weight, preferably 50 to 500 parts by weight, and more preferably 100 to 400 parts by weight, based on 100 parts by weight of the monomer components.

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

Examples of the radical generator include peroxides and azo compounds, with peroxides being preferred. As the peroxide, an inorganic peroxide or an organic peroxide is used.

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

The organic peroxide is not particularly limited as long as it is a known one used in emulsion polymerization, for example, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane. , 1-di-(t-hexylperoxy)cyclohexane, 1,1-di-(t-butylperoxy)cyclohexane, 4,4-di-(t-butylperoxy)n-butyl valerate, 2, 2-di-(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide, 1,1,3,3-tetraethyl Butyl hydroperoxide, t-butylcumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, diisobutyryl peroxide , di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, disuccinic acid peroxide, dibenzoyl peroxide, di(3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide , diisobutyrylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-tetramethylbutyl Peroxy neodecanate, t-hexyl peroxy pivalate, t-butyl peroxy neodecanate, t-hexyl peroxy pivalate, t-butyl peroxy pivalate, 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-hexulperoxyisopropyl monocarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5 -di(benzoylperoxy)hexane, t-butylperoxyacetate, t-hexylperoxybenzoate, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, etc. Among these, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide and the like are preferred.

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(propane-2-carboamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropanamide], 2,2'-azobis{2-[1-(2- hydroxyethyl)-2-imidazolin-2-yl]propane}, 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) and 2,2'-azobis{2-methyl-N-[ 1,1-bis(hydroxymethyl)-2-hydroxyethyl]propanamide} and the like.

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

As the reducing agent, any reducing agent used in a redox catalyst for emulsion polymerization can be used without particular limitation, but in the present invention, it is particularly preferable to use at least two types 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.

Examples of the metal ion compound in a reduced state include, but are not limited to, ferrous sulfate, sodium hexamethylenediaminetetraacetate, cuprous naphthenate, and the like. Among these, ferrous sulfate is preferred. These metal ion compounds in a reduced state can be used alone or in combination of two or more, and the amount used is usually 0.000001 to 0.000 parts per 100 parts by weight of the monomer components. 0.01 parts by weight, preferably 0.00001 to 0.001 parts by weight, more preferably 0.00005 to 0.0005 parts by weight.

Reducing agents other than metal ion compounds in their reduced state are not particularly limited, but include, for example, ascorbic acid or its salts such as ascorbic acid, sodium ascorbate, and potassium ascorbate; erythorbic acid, sodium erythorbate, and erythorbine. Erythorbic acid or its salts such as potassium acid; sulfinates such as sodium hydroxymethanesulfinate; sulfites of sodium sulfite, potassium sulfite, sodium hydrogen sulfite, aldehyde sodium hydrogen sulfite, potassium hydrogen sulfite; sodium pyrosulfite, potassium pyrosulfite , pyrosulfites such as sodium bisulfite and potassium bisulfite; thiosulfates such as sodium thiosulfate and potassium thiosulfate; Phosphorous acid or its salts; Pyrophosphorous acid or its salts such as pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, sodium hydrogen pyrophosphite, potassium hydrogen pyrophosphite; sodium formaldehyde sulfoxylate; and the like. Among these, ascorbic acid or its salts, sodium formaldehyde sulfoxylate, etc. are preferred, and ascorbic acid or its salts are particularly preferred.

These reducing agents other than metal ion compounds in a reduced state can be used alone or in combination of two or more, and the amount used is usually 0.001 parts by weight per 100 parts by weight of the monomer components. ~1 part by weight, preferably 0.005 to 0.5 part by weight, more preferably 0.01 to 0.3 part by weight.

A preferred combination of a metal ion compound in a reduced state and another reducing agent is ferrous sulfate and ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate, more preferably ferrous sulfate and ascorbate. and/or sodium formaldehyde sulfoxylate, most preferably a combination of ferrous sulfate and ascorbate. At this time, the amount of ferrous sulfate used is usually 0.000001 to 0.01 parts by weight, preferably 0.00001 to 0.001 parts by weight, and more preferably The amount of ascorbic acid or its salt and/or sodium formaldehyde sulfoxylate used is usually 0.001 to 1 part by weight per 100 parts by weight of the monomer component, in the range of 0.00005 to 0.0005 parts by weight. It is preferably 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 just that used during the emulsification of the monomer components, but it is usually 10 to 1000 parts by weight, preferably 50 parts by weight, based on 100 parts by weight of the monomer components used in the polymerization. The amount is adjusted to be in the range of 500 parts by weight, more preferably 80 to 400 parts by weight, and most preferably 100 to 300 parts by weight.

The emulsion polymerization reaction may be carried out in a conventional manner, and may be carried out in a batch, semi-batch or continuous manner. The polymerization temperature and polymerization time are not particularly limited, and can be appropriately selected depending on the type of polymerization initiator used. 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 when it is usually 80% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more, the produced acrylic rubber sheet has excellent strength properties. Moreover, it is suitable because there is no monomer odor. A polymerization terminator may be used to terminate the polymerization.

(solidification process)
The coagulation step in the method for producing an acrylic rubber sheet of the present invention is a step in which the obtained emulsion polymerization solution is brought into contact with a coagulation solution to produce hydrous crumb.

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

The coagulant used is not particularly limited, but metal salts are usually used. Examples of metal salts include alkali metal salts, salts of metals from group 2 of the periodic table, and other metal salts, preferably alkali metal salts and salts of metals from group 2 of the periodic table, more preferably salts of metals from group 2 of the periodic table. Metal salts, particularly preferred are magnesium salts.

Examples of alkali metal salts include sodium salts such as sodium chloride, sodium nitrate, and sodium sulfate; potassium salts such as potassium chloride, potassium nitrate, and potassium sulfate; and lithium salts such as lithium chloride, lithium nitrate, and lithium sulfate. Among these, sodium salts are preferred, and sodium chloride and sodium sulfate are particularly preferred.

Examples of Group 2 metal salts of the periodic table include magnesium chloride, calcium chloride, magnesium nitrate, calcium nitrate, magnesium sulfate, and calcium sulfate, with calcium chloride and magnesium sulfate being preferred.

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

These coagulants 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 0.01 to 100 parts by weight, based on 100 parts by weight of the monomer component. .1 to 50 parts by weight, more preferably 1 to 30 parts by weight. When the coagulant is in this range, it is preferable because the acrylic rubber can be sufficiently coagulated and the compression set resistance and water resistance of the acrylic rubber sheet can be highly improved when the acrylic rubber sheet is crosslinked.

The coagulant concentration of the coagulating liquid used is usually in the range of 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, particularly preferably 1.5 to 5% by weight. This is preferable because the particle size of the water-containing crumbs that are sometimes produced can be uniformly concentrated in a specific area.

Although there are no particular limitations on the temperature of the coagulating liquid, it is preferable that the temperature is usually 40°C or higher, preferably 40 to 90°C, and more preferably 50 to 80°C, since a uniform water-containing crumb will be produced.

The contact between the emulsion polymerization liquid and the coagulation liquid is not particularly limited, but for example, the method of adding the emulsion polymerization liquid to the coagulation liquid that is being stirred, or the method of adding the coagulation liquid to the stirred emulsion polymerization liquid. Any method may be used, but the method of adding the emulsion polymerization liquid to the coagulating liquid while being stirred makes the shape and crumb diameter of the generated water-containing crumbs uniform and concentrated, and greatly improves the cleaning efficiency of the emulsifier and coagulant. It is suitable.

The stirring speed (rotation speed) of the coagulated liquid being stirred is the rotation speed of the stirring blade of the stirring device, which is not particularly limited, but is usually 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm. , particularly preferably in the range of 400 to 800 rpm.

It is preferable to set the rotation speed to a speed that allows for vigorous stirring to a certain extent, as this allows the generated water-containing crumb particle size to be small and uniform.By setting the rotation speed to the above lower limit or more, it is possible to prevent excessively large and small crumb particle sizes. By keeping the amount below the above upper limit, the coagulation reaction can be more easily controlled.

The circumferential speed of the coagulated liquid being stirred, that is, the speed of the outer circumference of the stirring blade of the stirring device, is not particularly limited, but it is better to vigorously stir it to a certain degree to reduce the size of the water-containing crumb particles produced. It is suitable for uniformity, 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 or more. On the other hand, the upper limit of the circumferential speed is not particularly limited, but it 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 when solidification occurs. This is preferred because the reaction can be easily controlled.

By setting the above-mentioned conditions for the coagulation reaction in the coagulation process (contact method, solid content concentration of the emulsion polymerization liquid, concentration and temperature of the coagulation liquid, rotation speed and circumferential speed during stirring of the coagulation liquid, etc.) to a specific range, the formation The shape and crumb diameter of the water-containing crumbs are uniform and concentrated, and the removal of emulsifiers and coagulants during washing and dehydration is significantly improved, which is preferable.

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

The washing method is not particularly limited and may be any conventional method. For example, it can be carried out by mixing the produced water-containing crumb with a large amount of water.

The amount of water to be used is not particularly limited, but the amount per washing is usually 50 parts by weight or more, preferably 50 to 15,000 parts by weight, or more, based on 100 parts by weight of the monomer component. Preferably, the range is from 100 to 10,000 parts by weight, particularly preferably from 150 to 5,000 parts by weight, since the ash content in the acrylic rubber can be effectively reduced.

The temperature of the washing water is not particularly limited, but it is preferable to use warm water, usually 40°C or higher, preferably 40-100°C, more preferably 50-90°C, most preferably 60-90°C. It is preferable to use a temperature of 80° C. because the cleaning efficiency can be significantly increased.

By setting the temperature of the washing water to the above-mentioned lower limit or higher, the emulsifier and coagulant are liberated from the water-containing crumb, and the washing efficiency is further improved.

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

The number of washings is not particularly limited, and is usually 1 to 10 times, preferably multiple times, and more preferably 2 to 3 times. In addition, from the viewpoint of reducing the amount of coagulant remaining in the acrylic rubber finally obtained, it is desirable to wash with water more often, but it is preferable to specify the shape and diameter of the water-containing crumb and/or By setting the washing temperature within the above range, the number of washings can be significantly reduced.

(Dehydration, drying, molding process)
The dehydration, drying, and molding steps in the method for producing an acrylic rubber sheet of the present invention are performed by 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 is characterized in that it is dehydrated in a dehydration barrel to a water content of 1 to 40% by weight, then dried in a drying barrel to a water content of less than 1% by weight, and a sheet-like dry rubber is extruded from a die.

In the present invention, it is preferable that the hydrous crumb supplied to the screw extruder is one from which free water has been removed (drained) after washing.

Draining process In the method for producing an acrylic rubber sheet of the present invention, it is possible to improve the dewatering efficiency by providing a draining process in which free water is separated from the washed water-containing crumbs using a drainer after the washing process and before the dehydration/drying process. It is suitable for raising the temperature.

As the drainer, any known device can be used without particular limitation, such as a wire mesh, a screen, an electric sieve, etc., preferably a wire mesh or a screen.

There is no particular limitation on the opening of the colander, but when it is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, and more preferably 0.2 to 0.6 mm, water-containing crumb loss is minimized. In addition, it is suitable because water can be drained efficiently.

The water content of the water-containing crumb after draining, that is, the water content of the water-containing crumb input into the dehydration/drying process, is not particularly limited, but is usually 50 to 80% by weight, preferably 50 to 70% by weight, or more. The preferred range is 50 to 60% by weight.

The temperature of the hydrated crumb after draining, that is, the temperature of the hydrated crumb fed into the dehydration/drying process, is not particularly limited, but is usually 40°C or higher, preferably 40 to 100°C, more preferably 50 to 90°C. ℃, particularly preferably in the range of 55 to 85℃, most preferably 60 to 80℃, when the temperature is raised to a high specific heat of 1.5 to 2.5 KJ/kg・K like the acrylic rubber of the present invention. It is suitable because difficult water-containing crumbs can be efficiently dehydrated and dried using a screw extruder.

Dehydration of hydrous crumbs (dehydration barrel part)
Dewatering of the hydrous crumb is carried out in a dewatering barrel with a dewatering slit. The opening of the dehydration slit may be selected as appropriate depending on the conditions of use, but is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, and more preferably 0.2 to 0.6 mm. In addition, it is preferable because there is little loss of water-containing crumbs and the water-containing crumbs can be efficiently dehydrated.

The number of dehydration barrels in a screw type extruder is not particularly limited, but it is usually plural, preferably 2 to 10, more preferably 3 to 6, for dehydration of sticky acrylic rubber. This is suitable for efficient execution.

There are two ways to remove water from the water-containing crumbs in the dehydration barrel: water is removed from the dehydration slit in liquid form (drainage) and water is removed in vapor form (exhaust steam). Exhaust steam is defined and distinguished from pre-drying.

The water discharged from the dehydration slit during dehydration of hydrous crumbs may be in either liquid (drainage) or vapor (exhaust steam) state, but when dehydration is carried out using a screw type extruder equipped with multiple dehydration barrels, It is preferable to combine waste water and exhaust steam because it allows efficient dehydration of sticky acrylic rubber. For a screw type extruder equipped with three or more dehydration barrels, the choice between a drainage type dehydration barrel and an exhaust steam type dehydration barrel can be made as appropriate depending on the purpose of use. If the water content is to be reduced, the number of drainage type barrels is increased, and if the water content is to be reduced, the number of exhaust steam type barrels is increased.

The set temperature of the dehydration barrel is appropriately selected depending on the monomer composition of the 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 150°C. The temperature range is 130°C. The temperature setting of the dehydration barrel for dehydration in the drained state is usually 60 to 120°C, preferably 70 to 110°C, more preferably 80 to 100°C. The set temperature of the dehydration barrel for dehydration in the exhaust steam state is usually in the range of 100 to 150°C, preferably 105 to 140°C, more preferably 110 to 130°C.

There is no particular limitation on the water content after dehydration in drainage type dehydration in which water is squeezed out from water-containing crumbs, but it is usually 1 to 45% by weight, preferably 1 to 40% by weight, more preferably 5 to 35% by weight, especially Preferably, the content is 10 to 35% by weight, as productivity and ash removal efficiency are highly balanced.

When dehydrating adhesive acrylic rubber that has reactive groups using a centrifuge, etc., the acrylic rubber adheres to the dehydration slit, making it almost impossible to dehydrate it (the water content is approximately 45 to 55% by weight). ), in the present invention, it has become possible to reduce the water content to this extent by using a screw type extruder that has a dewatering slit and is forcibly squeezed by a screw.

When the water-containing crumb is dehydrated when a drain type dehydration barrel and an exhaust steam type dehydration barrel are provided, the water content after draining in the drain type dehydration barrel section is usually 5 to 45% by weight, preferably 10 to 40% by weight, and more preferably The water content after preliminary drying in the exhaust steam type dehydration barrel is usually 1 to 30% by weight, preferably 3 to 20% by weight, and more preferably 5 to 15% by weight.

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

Drying of water-containing crumbs (drying barrel section)
The drying of the water-containing crumb after the dehydration is performed in a drying barrel section under reduced pressure.

The degree of vacuum in the drying barrel may be selected as appropriate, but it is usually 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa, as this can efficiently dry the water-containing crumbs.

The temperature setting of the drying barrel may be selected as appropriate, but it is usually in the range of 100 to 250°C, preferably 110 to 200°C, more preferably 120 to 180°C, that the acrylic rubber will not fade or deteriorate. This is suitable because it allows efficient drying and reduces the amount of gel in the acrylic rubber sheet.

The number of drying barrels in the screw extruder is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 8. When there is a plurality of drying barrels, the degree of vacuum may be similar to that of all the drying barrels, or may be varied. When there are multiple drying barrels, the set temperature may be set to a similar temperature for all drying barrels or may be changed; It is preferable to set the temperature higher in (1) to increase the drying efficiency.

The moisture content of the dry rubber after drying is usually less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.6% by weight. In the present invention, the amount of gel in the acrylic rubber sheet insoluble in methyl ethyl ketone can be reduced by melt-extruding the dried rubber with the water content at this level (almost all water has been removed) in a screw extruder. suitable.

Dry rubber (die part)
The dried rubber dehydrated and dried in the screw portions of the dewatering barrel and drying barrel is sent to a rectifying die portion without a screw. A breaker plate and a wire mesh may or may not be provided between the screw part and the die part.

The dried rubber to be extruded is suitably extruded by making the die shape substantially rectangular and extruding it in the form of a sheet, since this results in a dry rubber with less air entrainment, high specific gravity, and excellent storage stability.

The resin pressure in the die part 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, there is little air entrainment (high specific gravity). Moreover, it is suitable for excellent productivity.
Screw type extruder and operating conditions The screw length (L) of the screw type extruder used may be appropriately selected depending on the purpose of use, but is usually 3000 to 15000 mm, preferably 4000 to 10000 mm, more preferably 4500 mm. ~8000mm.

The screw diameter (D) of the screw extruder used may be appropriately selected depending on the purpose of 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) between the screw length (L) and the screw diameter (D) of the screw type extruder used is not particularly limited, but is usually 10 to 100, preferably 20 to 80, and more. Preferably, when it is in the range of 30 to 60, the water content can be reduced to less than 1% by weight without reducing the molecular weight of the dry rubber or causing burning.

The rotation speed (N) of the screw extruder used may be appropriately selected depending on various conditions, but is usually 10 to 1000 rpm, preferably 50 to 750 rpm, more preferably 100 to 500 rpm, most preferably 120 rpm. It is preferable that the speed is between 300 rpm and 300 rpm, since the water content of the acrylic rubber and the amount of gel insoluble in methyl ethyl ketone can be efficiently reduced.

The extrusion rate (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, more preferably 400 to 1,000 kg/hr, and most preferably 500 kg/hr. ~800kg/hr.

The ratio (Q/N) between the extrusion amount (Q) and the rotation speed (N) of the screw type extruder used is not particularly limited, but is usually 2 to 10, preferably 3 to 8, more preferably ranges from 4 to 6.

Sheet-shaped dry rubber The dried rubber extruded from a screw extruder is preferably in the form of a sheet, since it can increase the specific gravity without entraining air and highly improve storage stability. Dry rubber sheets extruded from a screw extruder are usually cooled and cut to be used as acrylic rubber sheets.

The thickness of the sheet-like dry rubber extruded from a screw 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 for certain situations due to its excellent workability and productivity. In particular, since the thermal conductivity of dry rubber sheets is as low as 0.15 to 0.35 W/mK, the thickness of dry rubber sheets is usually 1 to 30 mm when increasing cooling efficiency and dramatically improving productivity. The range is preferably 2 to 25 mm, more preferably 3 to 15 mm, particularly preferably 4 to 12 mm.

The width of the sheet-like dry rubber extruded from the screw extruder is appropriately selected depending on the purpose of use, but 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 dry rubber extruded from the screw extruder is not particularly limited, but is usually in the range of 100 to 200°C, preferably 110 to 180°C, more preferably 120 to 160°C.

The moisture content of the dry rubber extruded from a screw extruder is not particularly limited, but is usually less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.6% by weight.

The complex viscosity at 100°C ([η] 100°C) of the sheet-like dry rubber extruded from a screw extruder is not particularly limited, but is usually 1,500 to 6,000 Pa·s, preferably 2 ,000 to 5,000 Pa·s, more preferably 2,500 to 4,000 Pa·s, most preferably 2,500 to 3,500 Pa·s, extrudability and shape retention as a sheet. and are highly balanced and suitable. That is, by setting it above the lower limit, the extrudability can be improved, and by setting it below the upper limit, it is possible to suppress deformation and breakage of the sheet-like dry rubber.

The sheet-like dry rubber extruded from the screw extruder may be folded and used as is, but it can usually be cut and used.

There are no particular limitations on how to cut the dry rubber sheet, but since the acrylic rubber used in the acrylic rubber sheet of the present invention has strong adhesiveness, it is necessary to cut the dry rubber sheet in a continuous manner without drawing in air. It is preferable to do this after cooling.

The cutting temperature of the sheet-like dry rubber is not particularly limited, but it is usually 60° C. or lower, preferably 55° C. or lower, more preferably 50° C. or lower, as this provides a high balance between cutting performance and productivity. It is.

The complex viscosity ([η]60°C) of the sheet-like dry rubber at 60°C is not particularly limited, but is usually 15,000 Pa·s or less, preferably 2,000 to 10,000 Pa·s, or more. Preferably, the pressure is in the range of 2,500 to 7,000 Pa·s, most preferably in the range of 2,700 to 5,500 Pa·s, since cutting can be performed continuously without entraining air.

The ratio of the complex viscosity at 100°C ([η] 100°C) and the complex viscosity at 60°C ([η] 60°C) of the sheet-like dry rubber ([η] 100°C/[η] 60°C) is: Although not particularly limited, it 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, most preferably 0.83. A range of 0.93 to 0.93 is preferable because air entrainment is small and cutting and productivity are highly balanced.

There are no particular limitations on the method of cooling the dried rubber sheet, and it may be left at room temperature. Forced cooling methods such as air cooling under air conditioning, water spraying, and immersion in water are preferred in order to increase productivity, and air cooling under air blowing or cooling is particularly preferred.

In the air cooling method for dry rubber sheets, for example, the dry rubber sheets are extruded from a screw extruder onto a conveyor such as a belt conveyor, and are conveyed and cooled while blowing cold air. The temperature of the cold air is not particularly limited, but is usually in the range of 0 to 25°C, preferably 5 to 25°C, 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. Although the cooling rate of the sheet-like dry rubber is not particularly limited, cutting is particularly easy when the cooling rate is usually 50°C/hr or more, more preferably 100°C/hr or more, and even more preferably 150°C/hr or more. This is suitable.

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

The acrylic rubber sheet thus obtained has superior operability and storage stability compared to crumb-like acrylic rubber, and can be used as it is or by laminating it into a bale.
<Acrylic rubber veil>
The acrylic rubber veil of the present invention is characterized by being formed by laminating the acrylic rubber sheets described above. The number of laminated sheets is appropriately selected depending on the size or weight of the acrylic rubber veil.

The size of the acrylic rubber veil 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, and the length is usually in the range of 300 to 1200 mm. , preferably from 400 to 1000 mm, more preferably from 500 to 800 mm, and the height is usually from 50 to 500 mm, preferably from 100 to 300 mm, more preferably from 150 to 250 mm.

Reactive group content, water content, ash content, amount and ratio of components in ash, specific gravity, gel content, pH, complex viscosity at 60°C ([η]60°C), and complex viscosity at 100°C of the acrylic rubber veil of the present invention Complex viscosity ([η] 100°C), ratio of complex viscosity at 100°C ([η] 100°C) to complex viscosity at 60°C ([η] 60°C) ([η] 100°C/[η ]60°C) and Mooney viscosity (ML1+4,100°C) are the same as the respective characteristic values of the acrylic rubber sheet.

Although the method for manufacturing the acrylic rubber veil of the present invention is not particularly limited, it can be easily manufactured by laminating the sheet-shaped dry rubber extruded from the screw type extruder after cooling and cutting.

The lamination temperature of the sheet-like dry rubber is not particularly limited, but it is usually 30° C. or higher, preferably 35° C. or higher, and more preferably 40° C. or higher, as this allows air caught during lamination to escape. The number of layers to be laminated may be appropriately selected depending on the size or weight of the acrylic rubber veil.

The acrylic rubber bale of the present invention obtained in this manner has superior operability, storage stability, and water resistance compared to crumb-like acrylic rubber, and can be used as is or by cutting the required amount into bunburys, rolls, etc. It can be used by adding it to a mixer.

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

The filler is not particularly limited, but examples include reinforcing fillers and non-reinforcing fillers, with reinforcing fillers being preferred.

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

These fillers can be used alone or in combination of two or more, and the blending amount is appropriately selected within a range that does not impair the effects of the present invention. The amount is usually 1 to 200 parts by weight, preferably 10 to 150 parts by weight, and more preferably 20 to 100 parts by weight.

The crosslinking agent may be selected as appropriate depending on the type of reactive group contained in the acrylic rubber constituting the acrylic rubber sheet or acrylic rubber veil and the intended use, but one that can crosslink the acrylic rubber sheet or acrylic rubber veil may be used. For example, polyvalent amine compounds such as diamine compounds and their carbonates; sulfur compounds; sulfur donor; triazinethiol compounds; polyvalent epoxy compounds; organic carboxylic acid ammonium salts; Conventionally known crosslinking agents such as oxides; polycarboxylic acids; quaternary onium salts; imidazole compounds; isocyanuric acid compounds; organic peroxides; and triazine compounds can be used. Among these, polyvalent amine compounds, carboxylic acid ammonium salts, dithiocarbamic acid metal salts and triazinethiol compounds are preferred, and hexamethylene diamine carbamate, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, benzoin Particularly preferred is ammonium acid, 2,4,6-trimercapto-1,3,5-triazine.

When the acrylic rubber sheet or acrylic rubber veil used is composed of carboxyl group-containing acrylic rubber, it is preferable to use a polyvalent amine compound and its carbonate as a crosslinking agent. Examples of the polyvalent amine compound include aliphatic polyvalent amine compounds such as hexamethylene diamine, hexamethylene diamine carbamate, N,N'-dicinnamylidene-1,6-hexane diamine; 4,4'-methylene dianiline, p -Phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(m-phenylene diisopropylidene) dianiline, 4,4'-(p-phenylene di isopropylidene) dianiline, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminobenzanilide, 4,4'-bis(4-aminophenoxy)biphenyl, m-xyly Aromatic polyvalent amine compounds such as diamine, p-xylylenediamine, and 1,3,5-benzenetriamine; and the like. Among these, hexamethylene diamine carbamate, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, and the like are preferred.

When the acrylic rubber sheet or acrylic rubber veil used is composed of epoxy group-containing acrylic rubber, the crosslinking agent is an aliphatic polyvalent amine compound such as hexamethylene diamine, hexamethylene diamine carbamate, and a carbonate thereof; 4. Aromatic polyvalent amine compounds such as 4'-methylene dianiline; carboxylic acid ammonium salts thereof such as ammonium benzoate and ammonium adipate; dithiocarbamate metal salts such as zinc dimethyldithiocarbamate; polyvalent carboxylic acids such as tetradecanedioic acid; Quaternary onium salts such as cetyltrimethylammonium bromide; imidazole compounds such as 2-methylimidazole; isocyanuric acid compounds such as ammonium isocyanurate; etc. can be used, and among these, carboxylic acid ammonium salts and dithiocarbamic acid metal salts are preferred. , ammonium benzoate is more preferred.

When the acrylic rubber sheet or acrylic rubber veil used is composed of halogen atom-containing acrylic rubber, it is preferable to use sulfur, a sulfur donor, or a triazinethiol compound as the crosslinking agent. Examples of the sulfur donor include dipentamethylenethiuram hexasulfide and triethylthiuram disulfide. Examples of triazine compounds 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 preferred.

These crosslinking agents can be used alone or in combination of two or more, and the amount thereof is usually 0.001 to 20 parts by weight, preferably 0.001 to 20 parts by weight, per 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 amount of the crosslinking agent within this range, it is possible to obtain sufficient rubber elasticity and to obtain excellent mechanical strength as a crosslinked rubber product.

The rubber mixture of the present invention may contain other rubber components other than the acrylic rubber sheet or acrylic rubber veil, if necessary.

Other rubber components that may be used as necessary are not particularly limited, and include, for example, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicone rubber, fluororubber, and olefin rubber. Examples include elastomers, styrene-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, and polysiloxane-based elastomers. The shape of the other rubber components is not particularly limited, and may be, for example, crumb-like, sheet-like, veil-like, or the like.

These other rubber components can be used alone or in combination of two or more. The amount of these other rubber components to be used is appropriately selected within a range that does not impair the effects of the present invention.

The rubber mixture of the present invention may contain an anti-aging agent, if necessary. Anti-aging agents include, but are not limited to, 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), Other phenolic antioxidants such as 2,6-di-t-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol; tris(nonylphenyl) Phosphite ester-based anti-aging agents such as phosphite, diphenylisodecyl phosphite, and tetraphenyldipropylene glycol diphosphite; Sulfur ester-based anti-aging agents such as dilauryl thiodipropionate; Phenyl-α-naphthylamine, phenyl-β- Naphthylamine, p-(p-toluenesulfonylamide)-diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, N,N-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p - Amine anti-aging agents such as phenylene diamine, butyraldehyde-aniline condensate; Imidazole anti-aging agents such as 2-mercaptobenzimidazole; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, etc. quinoline-based anti-aging agents; hydroquinone-based anti-aging agents such as 2,5-di-(t-amyl)hydroquinone; and the like. Among these, amine anti-aging agents are particularly preferred.

These anti-aging agents can be used alone or in combination of two or more, and the blending amount is 0.01 to 15 parts by weight per 100 parts by weight of the acrylic rubber sheet or acrylic rubber veil. The amount is preferably from 0.1 to 10 parts by weight, more preferably from 1 to 5 parts by weight.

The rubber mixture of the present invention contains the acrylic rubber sheet or acrylic rubber veil of the present invention, a filler, a crosslinking agent, and if necessary, other rubber components and anti-aging agents, and further contains, if necessary, Other commonly used additives, such as crosslinking aids, crosslinking accelerators, crosslinking retarders, silane coupling agents, plasticizers, processing aids, lubricants, pigments, colorants, antistatic agents, blowing agents, etc. can be mixed arbitrarily. These other compounding agents 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 effects of the present invention.

The method for producing the rubber mixture is not particularly limited, and for example, a method of mixing the filler, crosslinking agent, and other compounding agents that can be contained as necessary into an acrylic rubber sheet or an acrylic rubber veil can be used. For mixing, any means conventionally used in the rubber processing field, such as open rolls, Banbury mixers, various kneaders, etc., can be used. That is, using these mixers, the acrylic rubber sheet or acrylic rubber veil can be mixed with the filler, crosslinking agent, etc. by direct mixing, preferably by direct kneading.

In that case, the acrylic rubber sheet or acrylic rubber veil may be used as is or after being divided (cut, etc.).

There are no particular limitations on the mixing procedure for each component, but for example, after sufficiently mixing components that are difficult to react or decompose with heat, cross-linking agents, etc. that are easily reacted or decomposed with heat, are Two-stage mixing is preferred, in which mixing is performed at a low temperature for a short time. Specifically, it is preferable to mix the acrylic rubber sheet or acrylic rubber veil and the filler in the first stage, and then mix the crosslinking agent in the second stage. Other rubber components and anti-aging agents are usually mixed in the first stage, the crosslinking accelerator is mixed in the second stage, and other compounding agents may be selected as appropriate.

The Mooney viscosity (ML1+4,100°C; compound Mooney) of the rubber mixture of the present invention obtained in this way is not particularly limited, but is usually in the range of 10 to 150, preferably 20 to 100, more preferably 25 to 80. It is.

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

The rubber crosslinked product of the present invention is produced by molding the rubber mixture of the present invention in a molding machine corresponding to the desired shape, such as an extruder, injection molding machine, compressor, roll, etc., and then crosslinking by heating. It can be manufactured by performing a reaction and fixing the shape as a rubber crosslinked product. In this case, it may be crosslinked after being molded in advance, or crosslinking may be performed simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 150°C. The crosslinking temperature is usually 100 to 250°C, preferably 130 to 220°C, more preferably 150 to 200°C, and the crosslinking time is usually 0.1 minute to 10 hours, preferably 1 minute to 5 hours. As the heating method, methods used for crosslinking rubber such as press heating, steam heating, oven heating, and hot air heating may be selected as appropriate.

The crosslinked rubber product of the present invention may be further heated to perform secondary crosslinking depending on the shape, size, etc. of the crosslinked rubber product. Secondary crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., but is preferably carried out for 1 to 48 hours. The heating method and heating temperature may be selected as appropriate.

The rubber cross-linked product of the present invention can be used as sealing materials such as O-rings, packings, diaphragms, oil seals, shaft seals, bearing sheaths, mechanical seals, well head seals, seals for electrical and electronic equipment, and seals for air compressor equipment. ; A unit cell equipped with a rocker cover gasket installed at the connection between the cylinder block and the cylinder head, an oil pan gasket installed at the connection between the oil pan and the cylinder head or transmission case, a positive electrode, an electrolyte plate, and a negative electrode. Various gaskets such as gaskets for fuel cell separators installed between a pair of sandwiched housings and gaskets for top covers of hard disk drives; Cushioning materials, anti-vibration materials; Wire covering materials; Industrial belts; Tubes and hoses; Sheets. ; etc. is suitably used.

The rubber crosslinked product of the present invention can also be used as extrusion molded products and mold crosslinked products used in automobile applications, such as fuel tanks such as fuel hoses, filler neck hoses, vent hoses, paper hoses, and oil hoses. Suitable for use in various types of hoses such as air system hoses, turbo air hoses, mission control hoses, radiator hoses, heater hoses, brake hoses, air conditioner hoses, etc.

<Equipment configuration used for manufacturing acrylic rubber sheet>
Next, the configuration of an apparatus 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 example, an acrylic rubber manufacturing system 1 shown in FIG. 1 can be used to manufacture the acrylic rubber sheet according to the present invention.

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

The emulsion polymerization reactor is configured to perform the process related to the emulsion polymerization process described above. Although not shown in FIG. 1, this emulsion polymerization reactor includes, for example, a polymerization reaction tank, a temperature controller for controlling the reaction temperature, a motor, and a stirring device equipped with stirring blades. In an emulsion polymerization reactor, the monomer components for forming acrylic rubber are mixed with water and an emulsifier, and the mixture is appropriately stirred with a stirrer to form an emulsion, and emulsion polymerization is performed in the presence of a polymerization catalyst to form an emulsion polymerization solution. can be obtained. The emulsion polymerization reactor may be of a batch type, semi-batch type, or continuous type, and may be a tank type reactor or a tubular type reactor.

The coagulation apparatus 3 shown in FIG. 1 is configured to perform the processing related to the above-described coagulation process. As schematically illustrated in FIG. 1, the coagulation device 3 includes, for example, a stirring tank 30, a heating section 31 that heats the inside of the stirring tank 30, a temperature control section (not shown) that controls the temperature inside the stirring tank 30, It has a stirring device 34 including a motor 32 and stirring blades 33, and a drive control section (not shown) that controls the rotational speed and rotational speed of the stirring blades 33. In the coagulation device 3, water-containing crumb can be produced by bringing the emulsion polymerization liquid obtained in the emulsion polymerization reactor into contact with a coagulation liquid and coagulating it.

In the coagulation device 3, for example, the emulsion polymerization liquid and the coagulation liquid are brought into contact by a method in which the emulsion polymerization liquid is added to the coagulation liquid being stirred. That is, the stirring tank 30 of the coagulation device 3 is filled with a coagulation liquid, and the emulsion polymerization liquid is added to and brought into contact with the coagulation liquid to coagulate the emulsion polymerization liquid, thereby producing water-containing crumb.

The heating unit 31 of the coagulation device 3 is configured to heat the coagulation liquid 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 with a thermometer. It is configured. The temperature of the coagulating liquid in the stirring tank 30 is controlled by the temperature control section so that it is usually 40°C or higher, preferably in the range of 40 to 90°C, and more preferably in the range of 50 to 80°C.

The stirring device 34 of the coagulation device 3 is configured to stir the coagulation liquid filled in the stirring tank 30. Specifically, the stirring device 34 includes a motor 32 that generates rotational power, and stirring blades 33 that extend perpendicularly to the rotation axis of the motor 32. The stirring blades 33 can cause the coagulating liquid to flow within the coagulating liquid filled in the stirring tank 30 by rotating around a rotating shaft by the rotational power of the motor 32 . The shape, size, number, etc. of the stirring blades 33 are not particularly limited.

The drive control unit of the coagulation device 3 is configured to control the rotational drive of the motor 32 of the stirring device 34, and to set the number of rotations and the rotation speed of the stirring blades 33 of the stirring device 34 to predetermined values. The rotation of the stirring blade 33 is controlled by the drive control unit so that the number of stirring of the coagulation liquid is, for example, usually 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm, particularly preferably 400 to 800 rpm. be done. The peripheral speed of the coagulating liquid 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 blades 33 is controlled by the drive control unit so that Further, the drive control unit stirs the coagulating liquid so that the upper limit of the peripheral speed of the coagulating liquid 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. Rotation of the blade 33 is controlled.

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

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 with a thermometer. It is configured. As mentioned above, the temperature of the cleaning water in the cleaning 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. Ru.

The water-containing crumb washed by the washing device 4 is supplied to a screw extruder 5 which performs a dehydration process and a drying process. At this time, the water-containing crumb after washing is preferably supplied to the screw extruder 5 through a drainer 43 capable of separating free water. As the drainer 43, for example, a wire mesh, a screen, an electric sieve, etc. can be used.

Further, when the water-containing crumb after washing is supplied to the screw extruder 5, the temperature of the water-containing crumb is preferably 40°C or higher, and 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 extruder 5 can be maintained at 60° C. or higher. Alternatively, the water-containing crumb may be heated to a temperature of 40° C. or higher, preferably 60° C. or higher when being transported from the washing device 4 to the screw extruder 5. This makes it possible to effectively carry out the dehydration step and drying step, which are subsequent steps, and to significantly reduce the water content of the finally obtained dried rubber.

The screw extruder 5 shown in FIG. 1 is configured to perform the processes related to the dehydration process and drying process described above. Although a screw type extruder 5 is shown as a preferable example in FIG. 1, a centrifugal separator, a squeezer, etc. may be used as the dehydrator for performing the process related to the dehydration process, and A hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, etc. may be used as the dryer.

The screw extruder 5 is configured to mold the dried rubber obtained through the dehydration process and the drying process into a predetermined shape and discharge it. Specifically, the screw type extruder 5 includes a dehydration barrel section 53 that functions as a dehydrator for dehydrating the hydrous crumbs washed by the washing device 4, and a drying barrel section 53 that functions as a dryer for drying the hydrous crumbs. A barrel portion 54 is provided, and a die 59 having a molding function for molding a hydrous crumb is further provided on the downstream side of the screw extruder 5.

Hereinafter, the configuration of the screw type extruder 5 will be explained with reference to FIG. 2. FIG. 2 shows the configuration of a specific example suitable for the screw type extruder 5 shown in FIG. This screw type extruder 5 allows the above-described dehydration/drying process to be performed suitably.

The screw type extruder 5 shown in FIG. 2 is a twin screw type extrusion dryer including a pair of screws (not shown) in a barrel unit 51. The screw extruder 5 has a drive unit 50 that rotationally drives a pair of screws in a 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 extruder 5 has a die 59 at the downstream end of the barrel unit 51 (the right end in FIG. 2).

The barrel unit 51 extends from the upstream side to the downstream side (from the left side to the right side in FIG. 2) and includes a supply barrel section 52, a dehydration barrel section 53, and a drying barrel section 54.

The supply barrel section 52 includes two supply barrels, namely, a first supply barrel 52a and a second supply barrel 52b.

Further, the dehydration barrel section 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.

The drying barrel section 54 also includes eight drying barrels, namely, 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 drying barrel 54f, a seventh drying barrel 54g, and an eighth drying barrel 54h.

In this way, the barrel unit 51 is constructed by connecting the thirteen divided barrels 52a to 52b, 53a to 53c, and 54a to 54h from the upstream side to the downstream side.

Further, the screw type extruder 5 individually heats each of the barrels 52a to 52b, 53a to 53c, and 54a to 54h to separate the hydrous crumbs in each barrel 52a to 52b, 53a to 53c, and 54a to 54h to a predetermined level. It has a heating means (not shown) for heating to a certain temperature. The number of heating means corresponds to each barrel 52a to 52b, 53a to 53c, and 54a to 54h. As such a heating means, for example, a configuration is adopted in which high temperature steam is supplied from a steam supply means to a steam distribution jacket formed in each barrel 52a to 52b, 53a to 53c, and 54a to 54h. It is not limited to this. Further, the screw type extruder 5 has a temperature control means (not shown) that controls the set temperature of each heating means corresponding to each barrel 52a to 52b, 53a to 53c, and 54a to 54h.

Note that the number of installed supply barrels, dehydration barrels, and drying barrels that constitute each of the barrel parts 52, 53, and 54 in the barrel unit 51 is not limited to the embodiment shown in FIG. The number can be set depending on the water content of the water-containing crumb.

For example, the number of supply barrels installed in the supply barrel section 52 is, for example, 1 to 3. Further, the number of dehydration barrels installed in the dehydration barrel section 53 is preferably 2 to 10, for example, and more preferably 3 to 6, since water-containing crumbs of sticky acrylic rubber can be efficiently dehydrated. Further, the number of drying barrels installed in the drying barrel section 54 is preferably 2 to 10, and more preferably 3 to 8, for example.

The pair of screws in the barrel unit 51 are rotationally driven by a drive means such as a motor stored in the drive unit 50. The pair of screws extend from the upstream side to the downstream side in the barrel unit 51, and are driven to rotate so that the water-containing crumbs supplied to the supply barrel section 52 can be mixed and conveyed to the downstream side. It looks like this. The pair of screws is preferably of a biaxial meshing type in which the peaks and valleys are engaged with each other, thereby increasing the dewatering efficiency and drying efficiency of the water-containing crumb.

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

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

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

The first to third dehydration barrels 53a to 53c constituting the dehydration barrel section 53 have dehydration slits 56a, 56b, and 56c, respectively, for discharging moisture from the water-containing crumbs to the outside. A plurality of dewatering slits 56a, 56b, and 56c are formed in each of the dewatering barrels 53a to 53c, respectively.

The slit width, that is, the opening of each dewatering slit 56a, 56b, and 56c, may be appropriately selected depending on the usage conditions, and is usually 0.01 to 5 mm, which reduces the loss of water-containing crumbs and reduces the amount of water-containing crumbs. From the viewpoint of efficient dehydration, the thickness is preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm.

There are two ways to remove moisture from the water-containing crumbs in each of the dehydration barrels 53a to 53c of the dehydration barrel section 53: removing it in liquid form from the respective dehydration slits 56a, 56b, and 56c, and removing it in vapor form. . In the dehydration barrel section 53 of this embodiment, the case where water is removed in liquid form is defined as waste water, and the case where water is removed in vapor form is defined as exhaust steam.

In the dewatering barrel section 53, it is preferable to combine waste water and exhaust steam because it can efficiently reduce the moisture content of the adhesive acrylic rubber. In the dehydration barrel section 53, which dehydration barrel among the first to third dehydration barrels 53a to 53c is used to perform drainage or exhaust steam may be set as appropriate depending on the purpose of use, but it is usually manufactured. When reducing the amount of ash in the acrylic rubber, it is recommended to increase the number of dewatering barrels for draining water. 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 exhaust steam is performed in the third dehydration barrel 53c on the downstream side. Further, for example, when the dehydration barrel section 53 has four dehydration barrels, it is conceivable that, for example, three dehydration barrels on the upstream side perform drainage, and one dehydration barrel on the downstream side performs exhaust steam. On the other hand, when reducing the water content, it is preferable to increase the number of dehydration barrels for exhausting steam.

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

The drying barrel section 54 is a region where the dehydrated water-containing crumb is dried under reduced pressure. Among the first to eighth drying barrels 54a to 54h forming the drying barrel section 54, the second drying barrel 54b, the fourth drying barrel 54d, the sixth drying barrel 54f, and the eighth drying barrel 54h are as follows: It has vent ports 58a, 58b, 58c, and 58d for degassing, respectively. Vent piping (not shown) is connected to each of the vent ports 58a, 58b, 58c, and 58d.

Vacuum pumps (not shown) are connected to the ends of each vent pipe, respectively, and the inside of the drying barrel portion 54 is reduced to a predetermined pressure by the operation of these vacuum pumps. 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 pressure reduction in the drying barrel section 54.

The degree of pressure reduction in the drying barrel section 54 may be selected as appropriate, 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.

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

In each of the drying barrels 54a to 54h constituting the drying barrel section 54, the set temperatures in all the drying barrels 54a to 54h may be approximated or different; It is preferable to set the temperature on the downstream side (die 59 side) higher than the temperature on the die 53 side) because drying efficiency improves.

The die 59 is a mold placed at the downstream end of the barrel unit 51, and has a predetermined nozzle-shaped discharge port. The acrylic rubber that has been dried in the drying barrel section 54 passes through the discharge port of the die 59 and is extruded into a shape that corresponds to a predetermined nozzle shape. In the present invention, the shape of the acrylic rubber passing through the die 59 can be extruded into a sheet by making the nozzle shape of the die 59 approximately rectangular. A breaker plate or a wire mesh may or may not be provided between the screw and the die 59.

According to the screw extruder 5 according to the present embodiment, a hydrous crumb of acrylic rubber as a raw material is extruded into a sheet-like dry rubber in the following manner.

The hydrated crumb of acrylic rubber obtained through the washing process is supplied to the supply barrel portion 52 from the feed port 55 . The hydrous crumbs supplied to the supply barrel section 52 are sent from the supply barrel section 52 to the dehydration barrel section 53 by the rotation of a pair of screws within the barrel unit 51 . In the dehydration barrel section 53, as described above, water contained in the hydrous crumb is drained and steam is exhausted from the dehydration slits 56a, 56b, and 56c provided in the first to third dehydration barrels 53a to 53c, respectively. , the hydrous crumb is dehydrated.

The hydrous crumbs dehydrated in the dewatering barrel section 53 are sent to the drying barrel section 54 by rotation of a pair of screws in the barrel unit 51. The water-containing crumbs sent to the drying barrel section 54 are plasticized and mixed to become a melt, which generates heat and is conveyed to the downstream side while increasing its temperature. Then, the moisture contained in the molten acrylic rubber vaporizes, and the moisture (steam) is discharged to the outside through vent pipes (not shown) connected to the vent ports 58a, 58b, 58c, and 58d, respectively.

As described above, the water-containing crumb is dried by passing through the drying barrel section 54 and becomes a melted acrylic rubber.The acrylic rubber is supplied to the die 59 by the rotation of a pair of screws in the barrel unit 51, and is shaped into a sheet. It is extruded from the die 59 as dry rubber.

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

The rotational speed (N) of the pair of screws in the barrel unit 51 may be appropriately selected depending on various conditions, and is usually 10 to 1000 rpm, and is determined by the water content of the acrylic rubber sheet and the gel amount of methyl ethyl ketone insoluble matter. The speed is preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

The extrusion rate (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.

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

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

Hereinafter, as an example of the cooling device 6, a conveying cooling device 60 that cools a sheet-shaped dry rubber 10 formed into a sheet 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 conveying 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 extruder 5 by an air cooling method while conveying it. By using this conveyance type cooling device 60, the sheet-like dry rubber discharged from the screw extruder 5 can be suitably cooled.

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

The conveyor type cooling device 60 includes a conveyor 61 that conveys the sheet-like dry rubber 10 discharged from the die 59 of the screw extruder 5 in the direction of arrow A in FIG. It has a cooling means 65 for spraying.

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

The cooling means 65 is not particularly limited, but has a configuration that can, for example, blow cooling air sent from a cooling air generating means (not shown) onto the surface of the sheet-like dry rubber 10 on the conveyor belt 64. Examples include.

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

According to the conveying type cooling device 60 shown in FIG. By blowing cooling air, the sheet-like dry rubber 10 is cooled.

Note that the transport cooling device 60 is not particularly limited to a configuration including one conveyor 61 and one cooling means 65 as shown in FIG. 3, and may include two or more conveyors 61 and two or more corresponding It is also possible to have a configuration including a cooling means 65. 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 baling device 7 shown in FIG. 1 is configured to process dried rubber extruded from a screw extruder 5 and further cooled by a cooling device 6 to produce a bale in the form of a block. Although the weight and shape of the acrylic rubber bale produced by the bale forming device 7 are not particularly limited, for example, an approximately 20 kg acrylic rubber bale having a substantially rectangular parallelepiped shape is produced.

Further, the sheet-like dry rubber 10 produced by the screw extruder 5 may be laminated to produce an acrylic rubber veil. For example, a cutting mechanism for cutting the sheet-like dry rubber 10 may be provided in the baling device 7 disposed downstream of the transport type cooling device 60 shown in FIG. 3 . Specifically, the cutting mechanism of the baling device 7 continuously cuts the cooled dry rubber sheet 10 at predetermined intervals to process it into cut dry rubber sheets 16 of a predetermined size. It is configured as follows. By laminating a plurality of cut sheet-like dry rubber 16 cut into a predetermined size by a cutting mechanism, an acrylic rubber veil in which cut sheet-like dry rubber 16 is laminated can be manufactured.

When manufacturing an acrylic rubber veil in which cut sheet-like dry rubber 16 is laminated, it is preferable to laminate cut sheet-like dry rubber 16 at a temperature of 40° C. or higher, for example. By laminating the cut sheet-like dry rubber 16 at 40° C. or higher, good air release is achieved through further cooling and compression by its own weight.

The present invention will be explained in more detail below by giving Examples and Comparative Examples. In addition, "parts", "%" and "ratio" in each example are based on weight unless otherwise specified.
Various physical properties were evaluated according to the following methods.

[Monomer composition]
Regarding the monomer composition in acrylic rubber, the monomer composition of each monomer unit in acrylic rubber was confirmed by H-NMR, and it was confirmed that the activity of the reactive group remained in the acrylic rubber and its various reactions. The content of functional groups was confirmed by the following test method.

Further, 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, the polymerization reaction was an emulsion polymerization reaction, and the polymerization conversion rate was approximately 100%, with no unreacted monomers being observed. The amount used was the same as the amount used by the body.

[Reactive group content]
The content of reactive groups in the acrylic rubber was determined by measuring the content in the acrylic rubber sheet or 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 groups was calculated by dissolving an acrylic rubber sheet or an acrylic rubber veil in methyl ethyl ketone, adding a specified amount of hydrochloric acid thereto to react with the epoxy groups, and titrating the amount of remaining 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 into water, and titrating it with silver nitrate.

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

[Ash content]
The amount of each component (ppm) in the ash content of the acrylic rubber sheet or acrylic rubber veil is determined by pressing the ash sampled on the difference in the above ash content measurement onto a Φ20 mm titration filter paper, and performing XRF measurement using ZSX Primus (manufactured by Rigaku). did.

[Gel amount]
The gel amount (%) of the acrylic rubber sheet or acrylic rubber veil is the amount of insoluble matter in methyl ethyl ketone, and was determined by the following method.

Weigh approximately 0.2 g (Xg) of an acrylic rubber sheet or acrylic rubber veil, immerse it in 100 ml of methyl ethyl ketone, and leave it for 24 hours at room temperature.Then, use an 80-mesh wire mesh to filter out the insoluble matter in methyl ethyl ketone. The dry solid content (Yg) obtained by evaporating and solidifying the filtrate in which only the rubber component that dissolves by iodization in methyl ethyl ketone was weighed and calculated using the following formula.
Gel amount (%) = 100 x (X-Y)/X

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

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

[pH]
The pH of the acrylic rubber sheet or acrylic rubber veil was measured using a pH electrode after dissolving 6 g (±0.05 g) of acrylic rubber veil in 100 g of tetrahydrofuran, adding 2.0 ml of distilled water, and confirming complete dissolution. .

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

[Molecular weight and molecular weight distribution]
The weight average molecular weight (Mw) and molecular weight distribution (Mz/Mw) of acrylic rubber were measured using a solution in which 0.05 mol/L of lithium chloride and 0.01% of 37% concentrated hydrochloric acid were added to dimethylformamide as a solvent. These are the absolute molecular weight and absolute molecular weight distribution measured by the GPC-MALS method. Specifically, we incorporated a multi-angle laser light scattering photometer (MALS) and a differential refractometer (RI) into a GPC (Gel Permeation Chromatography) device, and measured the light scattering intensity and refraction of a molecular chain solution size-sorted by the GPC device. By measuring the rate difference over the elution time, the molecular weight of the solute and its content were sequentially calculated and determined. The measurement conditions and measurement method using the GPC device are as follows.
Column: TSKgel α-M 2 pieces (φ7.8mm x 30cm, manufactured by Tosoh Corporation)
Column temperature: 40℃
Flow rate: 0.8ml/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). Thereafter, filtration was performed using a 0.5 μm filter.

[Complex viscosity]
The complex viscosity η of an acrylic rubber sheet or an acrylic rubber veil was measured using a dynamic viscoelasticity measuring device "Rubber Process Analyzer RPA-2000" (manufactured by Alpha Technology Co., Ltd.) at a temperature dispersion of 473% strain and 1 Hz (40~ 120° C.) to determine the complex viscosity η at each temperature. Here, among the above-mentioned dynamic viscoelasticities, the dynamic viscoelasticity at 60°C is the complex viscosity coefficient η (60°C), the dynamic viscoelasticity at 100°C is the complex viscosity coefficient η (100°C), and the dynamic viscoelasticity at 100°C is the complex viscosity coefficient η (100°C). The values of η(°C)/η(60°C) and η(60°C)/η(100°C) were calculated.

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

[Workability evaluation]
The workability of the rubber samples was evaluated based on the following criteria regarding the workability of weight measurement work during the production of rubber mixtures.
◎: Can be easily measured 〇: Adhesive and adheres to some extent, but can be measured ×: Adheres to the measuring device and is highly viscous and difficult to handle

[Workability evaluation]
The processability of the rubber sample was determined by putting the rubber sample into a Banbury mixer heated to 50°C, masticating it for 1 minute, and then adding compounding agent A of the rubber mixture formulation listed in Table 1 to form the first stage rubber mixture. The time required for integration to show the maximum torque value, that is, BIT (Black Incorporation Time), was measured and evaluated using an index with Comparative Example 1 set as 100 (the smaller the index, the better the workability).

[Normal physical property evaluation]
The normal physical properties of the rubber samples were evaluated by measuring the breaking strength, 100% tensile stress, and breaking elongation of the rubber crosslinked product of the rubber samples according to JIS K6251, and using the following criteria.
(1) Breaking strength was evaluated as ◎ if it was 10 MPa or more, and × if it was less than 10 MPa.
(2) 100% tensile stress was evaluated as ◎ for 5 MPa or more and × for less than 5 MPa.
(3) The elongation at break was evaluated as ◎ when 150% or more and as × when less than 150%.

[Example 1]
In a mixing container equipped with a homomixer, 46 parts of pure water, 74.5 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of methoxyethyl acrylate, and 1.5 parts of mono-n-butyl fumarate. 1.8 parts of octyloxydioxyethylene phosphate sodium salt was added as an emulsifier and stirred to obtain a monomer emulsion.

Next, 170 parts of pure water and 3 parts of the monomer emulsion obtained above were charged into a polymerization reaction tank equipped with a thermometer and a stirring device, and the mixture was cooled to 12° C. under a nitrogen stream. Next, the remainder 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 into the polymerization reaction tank over a period of 3 hours. did. After that, the reaction was continued while maintaining the temperature inside the polymerization reaction at 23℃, and after confirming that the polymerization conversion rate had reached approximately 100%, hydroquinone was added as a polymerization terminator to stop the polymerization reaction. An emulsion polymerization solution was obtained.

The above anti-aging agent was added to a 2% aqueous magnesium sulfate solution (coagulation liquid) heated to 80°C and vigorously stirred (600 rotations: circumferential speed 3.1 m/s) in a coagulation tank equipped with a thermometer and a stirring device. The added emulsion polymerization solution was heated to 80° C. and added continuously to coagulate the polymer, which was then filtered to obtain water-containing crumb.

Next, 194 parts of warm water (70°C) was added into the coagulation tank, stirred for 15 minutes, water was drained, and 194 parts of warm water (70°C) was added again and stirred for 15 minutes to form water-containing crumbs. Washed. The washed water-containing crumb (water-containing crumb temperature: 65° C.) was supplied to a screw extruder, and was dehydrated and dried to extrude a sheet-like dry rubber having a width of 300 mm and a thickness of 10 mm. Next, the sheet-like dry rubber was cooled at a cooling rate of 200° C./hr using a conveying cooling device directly connected to the screw extruder.

The screw type extruder used in Example 1 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 and second dehydration barrels are adapted to carry out drainage, and the third dehydration barrel is adapted to carry out exhaust steam. The operating conditions of the screw extruder were as follows.

Water content:
・Water content of the hydrous crumb after draining in the second dewatering barrel: 20%
・Moisture content of hydrous crumb after exhausting steam in the third dehydration barrel: 10%
・Moisture content of the hydrous crumb after drying in the fifth drying barrel: 0.4%
Rubber temperature:
・Temperature of water-containing crumb supplied to the first supply barrel: 65°C
・Temperature of rubber discharged from screw extruder: 140℃
Set temperature for each barrel:
・First dehydration barrel: 90℃
・Second dehydration barrel: 100℃
・Third dehydration barrel: 120℃
・First drying barrel: 120℃
・Second drying barrel: 130℃
・Third drying barrel: 140℃
・Fourth drying barrel: 160℃
・Fifth drying barrel: 180℃
Operating conditions:
・Diameter of screw inside barrel unit (D): 132mm
・Total length of screw in barrel unit (L): 4620mm
・L/D: 35
・Rotation speed of the screw in the barrel unit: 135 rpm
・Rubber extrusion rate from die: 700kg/hr
・Die resin pressure: 2MPa

The extruded dry rubber sheet was cooled to 50° C. and then cut with a cutter to obtain an acrylic rubber sheet (A). The reactive group content, ash content, ash component content, specific gravity, gel content, glass transition temperature (Tg), water content, molecular weight, molecular weight distribution, complex viscosity, and Mooney viscosity ( ML1+4,100°C) and the results are shown in Table 2. Further, the workability of the acrylic rubber sheet (A) was evaluated and the results are shown in Table 2.

Next, 20 parts (20 kg) of the acrylic rubber sheets (A) were laminated to obtain an acrylic rubber veil (A) without the temperature becoming below 40°C. Reactive group content, ash content, ash component content, specific gravity, gel content, glass transition temperature (Tg), pH, antioxidant content, water content, molecular weight, molecular weight distribution of the obtained acrylic rubber veil (A) and complex viscosity were measured.

Next, using a Banbury mixer, 100 parts of the acrylic rubber sheet (A) and Compound A of "Formulation 1" listed in Table 1 were added and mixed at 50° C. for 5 minutes. The BIT at this time was measured to evaluate the workability of the acrylic rubber sheet, and the results are shown in Table 2.

Next, the obtained mixture was transferred to a roll at 50° C., and compounding agent B of “Formulation 1” shown in Table 1 was added and mixed to obtain a rubber mixture.

The obtained rubber mixture was put into a mold measuring 15 cm long, 15 cm wide and 0.2 cm deep, and pressed at 180° C. for 10 minutes while applying a press pressure of 10 MPa for primary crosslinking. The primary crosslinked product was further heated in a gear type oven at 180° C. for 2 hours to cause secondary crosslinking, thereby obtaining a sheet-like crosslinked rubber product. Then, a test piece of 3 cm x 2 cm x 0.2 cm was cut out from the obtained sheet-like crosslinked rubber product and its normal physical properties were evaluated. The results are shown in Table 2.

[Example 2]
The monomer components are 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 nonylphenyloxy. The same procedure as in Example 1 was carried out except that hexaoxyethylene phosphate sodium salt was used to obtain an acrylic rubber sheet (B) and an acrylic rubber veil (B), and their properties were evaluated. Table 2 shows the results for the acrylic rubber sheet (B).

[Example 3]
The monomer components are changed to 48.25 parts of ethyl acrylate, 50 parts of n-butyl acrylate, and 1.75 parts of mono-n-butyl fumarate, and the emulsifier is changed to tridecyloxyhexaoxyethylene phosphate sodium salt. Except for this, the same procedure as in Example 1 was carried out to obtain an acrylic rubber sheet (C) and an acrylic rubber veil (C), and each property (the compounding agent was changed to "Blend 2") was evaluated. Table 2 shows the results for the acrylic rubber sheet (C).

[Example 4]
The temperature of the first dehydration barrel of the screw type extruder was changed to 100°C and the temperature of the second dehydration barrel was changed to 120°C so that drainage was performed only in the first dehydration barrel, and An acrylic rubber sheet (D) and an acrylic rubber veil (D) were obtained in the same manner as in Example 3, except that the water content of the water-containing crumb after drainage was changed to 30%, and their properties were evaluated. Table 2 shows the results for the acrylic rubber sheet (D).

[Example 5]
Acrylic rubber was prepared in the same manner as in Example 4, except that the monomer components were changed to 28 parts of ethyl acrylate, 38 parts of n-butyl acrylate, 27 parts of methoxyethyl acrylate, 5 parts of acrylonitrile, and 2 parts of allyl glycidyl ether. A sheet (E) and an acrylic rubber veil (E) were obtained, and their properties were evaluated (by changing the compounding agent to Compound 3). Table 2 shows the results for the acrylic rubber sheet (E).

[Example 6]
Example 4 except that the monomer components were changed to 42.5 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. In the same manner as above, an acrylic rubber sheet (F) and an acrylic rubber veil (F) were obtained, and their properties were evaluated (by changing the compounding agent to Blend 4). Table 2 shows the results for the acrylic rubber sheet (F).

[Comparative example 1]
In a mixing container equipped with a homomixer, 46 parts of pure water, 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. 0.709 parts of sodium lauryl sulfate and 1.82 parts of polyoxyethylene dodecyl ether (molecular weight 1500) were added as emulsifiers and stirred to obtain a monomer emulsion.

Next, 170 parts of pure water and 3 parts of the monomer emulsion obtained above were charged into a polymerization reaction tank equipped with a thermometer and a stirring device, and the mixture was cooled to 12° C. under a nitrogen stream. Next, the remainder 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 into the polymerization reaction tank over a period of 3 hours. did. After that, the reaction was continued while maintaining the temperature inside the polymerization reaction at 23℃, and after confirming that the polymerization conversion rate had reached approximately 100%, hydroquinone was added as a polymerization terminator to stop the polymerization reaction. An emulsion polymerization solution was obtained.

Next, the emulsion polymerization solution containing the antiaging agent was heated to 80°C, and then a 0.7% sodium sulfate aqueous solution (coagulation solution) was added to the emulsion polymerization solution (rotation speed 100 rpm, circumferential speed 0.5 m/s). The polymer was continuously added to coagulate and filtered to obtain a hydrous crumb. 194 parts of industrial water was added to 100 parts of the obtained water-containing crumb, and the mixture was stirred at 25°C for 5 minutes. The water-containing crumb was washed four times by draining water from the coagulation tank, and then washed with an aqueous sulfuric acid solution of pH 3. After adding 194 parts and stirring at 25°C for 5 minutes, draining water from the coagulation tank and washing with acid once, adding 194 parts of pure water and washing with pure water once, It was dried in a hot air dryer at .degree. C. to obtain crumb-like acrylic rubber (G) having a water content of 0.4% by weight. The properties of the obtained crumb-like acrylic rubber (G) were evaluated and shown in Table 2.

From Table 2, it can be seen that the acrylic rubber of the present invention has a reactive group and has a weight average molecular weight (Mw) of 1,000,000 to 5,000,000, and the gel content of methyl ethyl ketone insoluble matter is 5% by weight or less. It can be seen that certain acrylic rubber sheets (A) to (F) are significantly superior in workability, processability, and normal physical properties (strength properties) (Examples 1 to 6).

In terms of workability, the acrylic rubber sheets (A) to (F) of the present invention are easy to handle and do not lose their shape, compared to crumb-like acrylic rubber (G), which is highly viscous and sticks together, making it difficult to handle. It can be seen that the workability is significantly superior (comparison between Examples 1 to 6 and Comparative Example 1).

Regarding processability, in the present invention, the polymerization conversion rate of emulsion polymerization is increased in order to improve strength properties, but as the polymerization conversion rate is increased, the gel amount increases rapidly, which deteriorates the processability of acrylic rubber. However, by drying and melting and kneading in a screw extruder to a virtually moisture-free state (moisture content less than 1%), the rapidly increasing gel disappears, and the processability and strength properties of the acrylic rubber veil are improved. (Comparison between Examples 1 to 6 and Comparative Example 1).

Regarding the strength properties, it can be seen that the acrylic rubber sheets (A) to (F) produced according to the present invention have excellent normal physical properties in terms of strength properties without the reactive groups falling off (Examples 1 to 6). .

From Table 2, the amount of reactive groups, specific gravity, gel amount, glass transition temperature (Tg), pH, water content, weight average molecular weight (Mw), z average molecular weight (Mz), and weight average molecular weight (Mw) of the present invention are shown. (Mz/Mw), complex viscosity η at 100°C (100°C), complex viscosity η at 60°C (60°C), ratio of complex viscosity at 100°C and 60°C (η100°C/η60°C) It can be seen that the acrylic rubber sheets (A) to (F) in which the ratio is within a specific range are excellent in workability, processability, and normal physical properties (strength properties) (Examples 1 to 6).

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

Claims (12)

a monomer composition of 70 to 99.9% by weight of bonding units derived from at least one (meth)acrylic ester selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid alkoxyalkyl esters; An acrylic rubber containing 0.01 to 20% by weight of bonding units derived from a reactive group-containing monomer and 0 to 30% by weight of bonding units derived from other monomers, and having a weight average molecular weight (Mw) of 1, 000,000 to 5,000,000, the ratio of z average molecular weight (Mz) to weight average molecular weight (Mw) (Mz/MW) is 1.3 or more , and the ash content is 1% by weight or less. An acrylic rubber sheet having a water content of less than 1% by weight, a pH of 6 or less, and a gel amount of methyl ethyl ketone insoluble matter of 10 % by weight or less. The acrylic rubber sheet according to claim 1, wherein the amount of acrylic rubber in the acrylic rubber sheet is 95% by weight or more. The acrylic rubber sheet according to claim 1 or 2, wherein the reactive group-containing monomer has at least one functional group selected from the group consisting of a carboxyl group, an epoxy group, and a halogen group. The acrylic rubber sheet according to any one of claims 1 to 3, wherein the content of at least one element selected from the group consisting of sodium, sulfur, calcium, magnesium, and phosphorus in the ash is 50% by weight or more. . The acrylic rubber sheet according to any one of claims 1 to 4, wherein the acrylic rubber sheet is a melt-kneaded sheet. The acrylic rubber sheet according to any one of claims 1 to 4, wherein the gel amount of methyl ethyl ketone insoluble matter is 5 % by weight or less. At least one (meth)acrylic acid ester selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester 70 to 99.9% by weight, reactive group-containing monomer 0.01 A monomer component consisting of ~20% by weight and 0~30% by weight of bonding units derived from other monomers is emulsified with water and an emulsifier, and emulsion polymerized in the presence of a polymerization catalyst to a polymerization conversion rate of 90% by weight or more. an emulsion polymerization step to obtain an emulsion polymerization solution;
a coagulation step of adding the obtained emulsion polymerization liquid to a coagulation liquid being stirred to produce a hydrous crumb;
a cleaning step of cleaning the generated water-containing crumb;
The washed water-containing crumb is dehydrated in the dehydration barrel to a water content of 1 to 40% by weight using a dehydration barrel having a dehydration slit , a drying barrel under reduced pressure, and a die at the tip, and then dried. A method for producing an acrylic rubber sheet, comprising dehydration, drying, and molding steps of drying in a barrel to a moisture content of less than 1% by weight and extruding the melt-kneaded sheet-like dried rubber from a die. 8. The method for producing an acrylic rubber sheet according to claim 7, wherein an emulsifier containing a phosphate ester salt is used as an emulsifier in the emulsion polymerization step. The method for producing an acrylic rubber sheet according to claim 7 or 8, wherein in the coagulation step, an aqueous solution of an alkali metal salt or a Group 2 metal salt of the periodic table is used as the coagulation liquid . An acrylic rubber veil formed by laminating the acrylic rubber sheets according to any one of claims 1 to 6 . A rubber mixture obtained by mixing the acrylic rubber sheet according to any one of claims 1 to 6 or the acrylic rubber veil according to claim 10 with a reinforcing agent and a crosslinking agent. A crosslinked rubber product obtained by crosslinking the rubber mixture according to claim 11.