JP7296329B2 - Acrylic rubber sheet with excellent storage stability and workability - Google Patents

Description

TECHNICAL FIELD 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 rubber crosslinked product, and more particularly, an acrylic rubber sheet excellent in storage stability and workability, a method for producing the same, and the acrylic rubber. The present invention relates to an acrylic rubber veil obtained by laminating sheets, a rubber mixture obtained by mixing the acrylic rubber sheet or the acrylic rubber veil, a method for producing the same, and a crosslinked rubber obtained by crosslinking the same.

Acrylic rubber is a polymer whose main component is acrylic acid ester, and is generally known as a rubber with excellent heat resistance, oil resistance, and ozone resistance. Used with the addition of an inhibitor.

For example, Patent Document 1 (International Publication No. 2018/139466 pamphlet) discloses that a monomer component containing ethyl acrylate, n-butyl acrylate, monobutyl fumarate, etc. is mixed with pure water, sodium lauryl sulfate, and polyoxy Ethylene dodecyl ether was stirred to obtain a monomer emulsion, and ferrous sulfate, sodium ascorbate and potassium persulfate aqueous solutions were continuously added dropwise over 3 hours to achieve a polymerization conversion rate of 95%. To the liquid, a 50% by weight aqueous dispersion of 3-(3,5-tert-butyl-4-hydroxyphenyl)stearyl propionate (50 parts of an aqueous solution of 0.2% by weight of sodium lauryl sulfate, (3,5- Di-tert-butyl-4-hydroxyphenyl) 50 parts of stearyl propionate was added and mixed) or 50% by weight aqueous dispersion of 2,4-bis[(octylthio)methyl]-6-methylphenol (0.2 (prepared by adding and mixing 50 parts by weight of 2,4-bis[(octylthio)methyl]-6-methylphenol to 50 parts by weight of an aqueous solution of sodium lauryl sulfate at 85°C by weight). and coagulated with sodium sulfate to produce wet crumbs, then the produced wet crumbs were washed with industrial water four times, washed with acid at pH 3 once, and washed once with pure water. discloses a method for producing a crumb-shaped acrylic rubber which can suppress contamination of a polymerization apparatus during polymerization and has excellent initial mechanical strength by drying at 160° C. for 10 minutes in a hot air dryer. It is also described that according to this method, wet crumbs washed with a screw-type extruder dryer can be dried at 150° C. or higher. However, in addition to heat resistance, it has been required to improve workability and storage stability under severe environments.

Regarding the amount of gel of acrylic rubber, for example, Patent Document 2 (Japanese Patent No. 3599962) discloses that 95 to 99.9% by weight of alkyl acrylate or alkoxyalkyl acrylate and two radically reactive unsaturated groups with different reactivities are used. Acrylic rubber obtained by copolymerizing 0.1 to 5% by weight of the above polymerizable monomers in the presence of a radical polymerization initiator and having a gel fraction of 5% by weight or less of the acetone-insoluble portion, reinforcing property Disclosed is an acrylic rubber composition comprising a filler and an organic peroxide vulcanizing agent and having excellent extrusion processability such as extrusion rate, die swell and surface texture. The acrylic rubber with a very small gel fraction of acetone-insoluble matter used here has a gel fraction of acetone-insoluble matter obtained in the normal acidic range of the polymerization solution (pH 4 before polymerization, pH 3.4 after polymerization). It is obtained by adjusting the pH of the polymerization liquid to pH 6 to 8 with sodium hydrogen carbonate or the like for acrylic rubber with a high (60%) Specifically, water, sodium lauryl sulfate and polyoxyethylene nonylphenyl ether as emulsifiers, sodium carbonate and boric acid were charged and adjusted to 75° C., then t-butyl hydroperoxide, Rongalit, disodium ethylenediaminetetraacetate, Ferrous sulfate was added (the pH at this time was 7.1), and then ethyl acrylate and allyl methacrylate monomer components were added dropwise for emulsion polymerization. It is salted out with water, washed with water and dried to obtain acrylic rubber. However, acrylic rubber, which is mainly composed of (meth)acrylic acid ester, has problems in handling, such as decomposing in the neutral to alkaline range and poor storage stability. The acrylic rubber used had a problem of poor mechanical strength due to loss of reactive groups (crosslinking points) such as carboxyl groups, epoxy groups and chlorine atoms.

Further, in Patent Document 3 (International Publication No. 2018/143101 pamphlet), a (meth)acrylic acid ester and an ionic crosslinkable monomer are emulsion-polymerized, and a complex viscosity at 100 ° C. ([η] 100 ° C.) 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 C) is 0.8 or less, a technique is disclosed for improving the extrusion moldability, particularly the discharge rate, discharge length and surface texture of a rubber composition containing a reinforcing agent and a cross-linking agent. The tetrahydrofuran (THF)-insoluble gel amount of the acrylic rubber used in the technique is 80% by weight or less, preferably 5 to 80% by weight. It is described that extrudability deteriorates when the amount of THF-insoluble gel is less than 5%. The acrylic rubber used has a weight average molecular weight (Mw) of 200,000 to 1,000,000. When the weight average molecular weight (Mw) exceeds 1,000,000, the acrylic rubber exhibits high viscoelasticity. It is described that it becomes too much and is not preferable. However, there has been a demand for a material that is highly balanced between high strength and workability during kneading such as Banbury, and an improvement in storage stability has also been demanded.

International Publication No. 2018/139466 pamphlet Japanese Patent No. 3599962 International Publication No. 2018/143101 Pamphlet

The present invention has been made in view of such circumstances, and provides an acrylic rubber sheet excellent in storage stability and workability, a method for producing the same, an acrylic rubber veil formed by laminating the acrylic rubber sheet, and the acrylic rubber sheet. Alternatively, an object of the present invention is to provide a rubber mixture containing an acrylic rubber veil, a method for producing the same, and a crosslinked rubber product thereof.

As a result of intensive research in view of the above problems, the present inventors have found that a (meth)acrylic acid ester is the main component and is composed of an acrylic rubber with a specific molecular weight, and the amount of gel insoluble in a specific solvent is specific and a liquid anti-aging agent. The present inventors have found that an acrylic rubber sheet containing this is remarkably excellent in storage stability and workability.

The present inventors also determined the structure and type of the liquid antioxidant, the molecular weight distribution in the high molecular weight region, the molecular weight, the pH, the specific gravity, the amount of gel and the amount of ash, thereby improving the storage stability and processing of the acrylic rubber veil. It was found that the properties were further improved.

The present inventors also added a liquid anti-aging agent to the emulsion polymerization liquid after emulsion polymerization of the monomer component mainly composed of (meth) acrylic acid ester, and specified water-containing crumbs after washing. After dehydration is performed by squeezing water out to a specific water content with a screw-type extruder, it is dried to a state that does not substantially contain water (specific water content), and then extruded into a dry rubber sheet to improve storage stability and processability. We have found that an excellent acrylic rubber sheet can be produced.

The present inventors also melt-kneaded a liquid anti-aging agent and an acrylic rubber in a state in which the washed water-containing crumbs are dried to a specific water content that does not substantially contain water with a specific screw type extruder. It has been found that an acrylic rubber sheet with improved uniform fine dispersibility and excellent storage stability and heat resistance can be efficiently produced.

The present inventors also found that if the polymerization conversion rate of the emulsion polymerization is increased in order to improve the strength properties of the acrylic rubber having a reactive group, the amount of gel insoluble in the specific solvent increases rapidly and the workability deteriorates. However, by drying and melt-kneading the washed wet crumbs with a screw extruder to a state that does not substantially contain water (specified amount of water), the amount of gel insoluble in the specific solvent, which increased rapidly, disappeared and reacted. The present inventors have found that an acrylic rubber sheet can be produced that is highly balanced in terms of strength properties, workability and storage stability without reducing the number of functional groups.

The present inventors have further found that the storage stability and water resistance of the acrylic rubber sheet are highly balanced by squeezing (dehydrating) the water content from the washed water-containing crumbs to a specific water content.

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

Thus, according to the present invention, an acrylic rubber containing (meth)acrylic acid ester as a main component and having a weight average molecular weight (Mw) of 100,000 to 5,000,000 is used, and the methyl ethyl ketone insoluble portion has a gel amount of 50. Provided is an acrylic rubber sheet containing no more than weight percent and a liquid anti-aging agent.

In the acrylic rubber sheet of the present invention, the content of the liquid antioxidant is preferably in the range of 0.001 to 15% by weight.

In the acrylic rubber sheet of the present invention, the liquid antioxidant preferably has a hindered structure.

In the acrylic rubber sheet of the present invention, the liquid anti-aging agent is preferably a phenol-based anti-aging agent.

（Ｒ１は、イソプロピル基又はｔ－ブチル基を示し、Ｒ２は、炭素数１～１２のアルキル基を示す。）で表されるヒンダードフェノール系老化防止剤であることが好ましい。 In the acrylic rubber sheet of the present invention, the liquid antioxidant is represented by general formula (1)

(R1 represents an isopropyl group or a t-butyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms) is preferred.

In the acrylic rubber sheet of the present invention, the ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) is preferably 1.3 or more.

The acrylic rubber sheet of the present invention preferably has a weight average molecular weight (Mw) of 1,000,000 or more.

The acrylic rubber sheet of the present invention preferably has a pH of 6 or less.

The acrylic rubber sheet of the present invention preferably has a specific gravity of 0.7 or more.

The acrylic rubber sheet of the present invention preferably has an ash content of 0.5% by weight or less.

According to the present invention, an emulsion polymerization step of emulsifying a monomer component containing (meth)acrylic acid ester as a main component with water and an emulsifier and performing emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid; An antiaging agent addition step of adding a liquid antiaging agent to the obtained emulsion polymerization liquid, a coagulation step of bringing the emulsion polymerization liquid to which the liquid antiaging agent is added into contact with a coagulation liquid to generate water-containing crumbs, and the generated water-containing crumbs. and a washing step of washing the washed water-containing crumbs in a dehydration barrel using a dehydration barrel having a dehydration slit, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip to a water content of 1 to 40% by weight. A method for producing an acrylic rubber sheet is provided, comprising a dewatering, drying and forming step of dehydrating and then drying in a drying barrel to a moisture content of less than 1% by weight and extruding the dry rubber sheet through a die.

In the method for producing an acrylic rubber sheet of the present invention, it is preferable that the emulsion polymerization has a polymerization conversion rate of 90% by weight or more.

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

According to the present invention, there is also provided a method for manufacturing an acrylic rubber veil in which the above acrylic rubber sheets are laminated.

In the method for producing an acrylic rubber veil of the present invention, the lamination temperature of the acrylic rubber sheet is preferably 30° C. or higher.

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

According to the present invention, there is also provided a method for producing a rubber mixture, characterized by mixing a reinforcing agent and a cross-linking agent with the above acrylic rubber sheet or acrylic rubber veil in a mixer.

According to the present invention, there is also provided a method for producing a rubber mixture in which a cross-linking agent is added after mixing the above acrylic rubber sheet or acrylic rubber veil with a reinforcing agent.

According to the present invention, there is further provided a cross-linked rubber obtained by cross-linking the above rubber mixture.

According to the present invention, an acrylic rubber sheet excellent in storage stability and workability, a method for producing the same, an acrylic rubber veil obtained by laminating the acrylic rubber sheet, and a rubber mixture obtained by mixing the acrylic rubber sheet or the acrylic rubber veil. and a method for producing the same, and a cross-linked rubber obtained by cross-linking 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 one embodiment of the present invention; FIG. FIG. 2 is a diagram showing the configuration of the screw-type extruder of FIG. 1; FIG. 2 is a diagram showing the configuration of a transport-type cooling device used as the cooling device in FIG. 1;

The acrylic rubber sheet of the present invention is made of an acrylic rubber having a weight average molecular weight (Mw) of 100,000 to 5,000,000, the main component of which is a (meth)acrylic acid ester, and a gel amount of the insoluble portion of methyl ethyl ketone is It is characterized by containing a liquid anti-aging agent in an amount of 50% by weight or less.

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

The acrylic rubber constituting the acrylic rubber sheet of the present invention contains at least one (meth)acrylic acid ester selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid alkoxyalkyl esters. It is preferable because the properties of the crosslinked product of the rubber sheet can be improved to a high degree.

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

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

The (meth)acrylic acid alkyl ester is not particularly limited, but usually has a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms, preferably having an alkyl group having 1 to 8 carbon atoms (meth)acrylic acid alkyl ester. ) alkyl acrylates, more preferably alkyl (meth)acrylates having an alkyl group of 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. Butyl, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylic acid n-butyl is preferred, and ethyl acrylate and n-butyl acrylate are more preferred.

The (meth)acrylic acid alkoxyalkyl ester is not particularly limited, but usually has 2 to 12 alkoxyalkyl groups (meth)acrylic acid alkoxyalkyl ester, preferably 2 to 8 alkoxyalkyl groups (meth)acrylic acid alkoxyalkyl ester having 2 to 8 alkoxyalkyl groups ) alkoxyalkyl acrylates, more preferably alkoxy(meth)acrylates having an alkoxyalkyl group having 2 to 6 carbon atoms.

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

These (meth)acrylic acid esters may be used alone or in combination of two or more. ~99.5 wt%, most preferably 87-99 wt%. If the amount of (meth)acrylic acid ester in the monomer component is excessively small, the obtained acrylic rubber may have poor weather resistance, heat resistance, and oil resistance, which is undesirable.

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

Although the monomer having a carboxyl group is not particularly limited, an ethylenically unsaturated carboxylic acid can be preferably used. Examples of ethylenically unsaturated carboxylic acids include ethylenically unsaturated monocarboxylic acids, ethylenically unsaturated dicarboxylic acids, and ethylenically unsaturated dicarboxylic acid monoesters. Esters are preferable because they can further enhance the resistance to compression set when acrylic rubber is used as a rubber crosslinked product.

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-ethylacrylic acid, crotonic acid, Cinnamic acid and the like can be mentioned.

The ethylenically unsaturated dicarboxylic acid is not particularly limited, but is preferably an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms. Maleic acid and the like can be mentioned. Incidentally, the ethylenically unsaturated dicarboxylic acids also include those existing as anhydrides.

Although the ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, 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. and an alkyl monoester having 2 to 8 carbon atoms with an ethylenically unsaturated dicarboxylic acid, more preferably an alkyl monoester having 2 to 6 carbon atoms and butenedioic 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. butenedioic 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 and monoalkyl esters; among these, mono-n-butyl fumarate and mono-n-butyl maleate are preferred, and mono-n-butyl fumarate is particularly preferred.

Examples of the epoxy group-containing monomer 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, (meth)acrylic acid (haloacetylcarbamoyl oxy)alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, haloacetyl group-containing unsaturated monomers, and the like.

Examples of unsaturated alcohol esters of halogen-containing saturated carboxylic acids include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate. (Meth)acrylate haloalkyl esters include, for example, 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. (Meth)acrylic acid haloacyloxyalkyl esters include, for example, 2-(chloroacetoxy)ethyl (meth)acrylate, 2-(chloroacetoxy)propyl (meth)acrylate, 3-(chloroacetoxy)acrylate (meth)acrylate ) propyl, 3-(hydroxychloroacetoxy)propyl (meth)acrylate, and the like. Examples of (haloacetylcarbamoyloxy)alkyl esters of (meth)acrylic acid include 2-(chloroacetylcarbamoyloxy)ethyl (meth)acrylate and 3-(chloroacetylcarbamoyloxy)propyl (meth)acrylate. be done. Halogen-containing unsaturated ethers include, for example, chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, 3-chloropropyl allyl ether and the like. Halogen-containing unsaturated ketones include, for example, 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, 2-chloroethyl allyl ketone, and the like. Examples of halomethyl group-containing aromatic vinyl compounds include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, p-chloromethyl-α-methylstyrene and the like. Halogen-containing unsaturated amides include, for example, N-chloromethyl(meth)acrylamide. Haloacetyl group-containing unsaturated monomers include, for example, 3-(hydroxychloroacetoxy)propyl allyl ether, p-vinylbenzyl chloroacetate and the like.

These reactive group-containing monomers may be used alone or in combination of two or more. The 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 used as necessary are not particularly limited as long as they are copolymerizable with the above monomers. Examples include aromatic vinyls, ethylenically unsaturated nitriles, acrylamide monomers, and others. and olefinic monomers. Examples of aromatic vinyl include styrene, α-methylstyrene, divinylbenzene and the like. Examples of ethylenically unsaturated nitriles include acrylonitrile and methacrylonitrile. Examples of acrylamide-based monomers include acrylamide and methacrylamide. Other olefinic monomers include, for example, ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, butyl vinyl ether and the like.

These other monomers may be used alone or in combination of two or more. 15 parts by weight, most preferably in the range of 0 to 10 parts by weight.

<Acrylic rubber>
The acrylic rubber constituting the acrylic rubber sheet of the present invention is composed of the above monomer components and preferably has a reactive group.

The reactive group is not particularly limited and is appropriately selected according to the purpose of use, but preferably at least one functional group selected from the group consisting of carboxyl group, epoxy group and halogen group, more preferably carboxyl When it is a group, the properties of the crosslinked product of the acrylic rubber sheet can be improved to a high degree, which is preferable. As the reactive group, an ion-reactive group such as a carboxyl group or an epoxy group is preferable because it can particularly improve the water resistance. As the acrylic rubber having such a reactive group, a reactive group may be imparted to the acrylic rubber by a post-reaction, but the acrylic rubber is preferably obtained by copolymerizing a reactive group-containing monomer.

The content of the reactive group may be appropriately selected depending on the purpose of use. Workability, strength properties, compression set resistance, oil resistance, oil resistance, Properties such as cold resistance and water resistance are highly balanced and suitable.

Specific examples of the acrylic rubber constituting the acrylic rubber sheet of the present invention include a (meth)acrylic acid ester, a reactive group-containing monomer, and optionally other copolymerizable monomers. in the acrylic rubber, the (meth)acrylic acid ester is usually 50% by weight or more, preferably 70 to 99.9% by weight, more preferably 80 to 99.5% by weight, particularly preferably 87 to 99% by weight. %, and the reactive group-containing monomer is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, particularly preferably 1 to The range is 3% by weight, and other monomers are usually 0 to 30% by weight, preferably 0 to 20% by weight, more preferably 0 to 15% by weight, particularly preferably 0 to 10% by weight. be. By setting these monomers in the acrylic rubber within this range, the object 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 are markedly improved, which is preferable. be.

The weight average molecular weight (Mw) of the acrylic rubber constituting the acrylic rubber sheet of the present invention is 100,000 to 5,000,000, preferably 500,000 to 4,000, as an absolute molecular weight measured by GPC-MALS. ,000, more preferably 700,000 to 3,000,000, and most preferably 1,000,000 to 2,500,000, the processability, strength characteristics, and Compression set resistance is highly balanced and suitable. In addition, the weight-average molecular weight (Mw) of the acrylic rubber is usually 1,000,000 or more, preferably 1,000,000, preferably 1,000,000, preferably 1,000,000, preferably 1,000,000. 000 to 5,000,000, more preferably 1,000,000 to 4,000,000, particularly preferably 1,100,000 to 3,000,000, most preferably 1,200,000 to 2,500 , 000.

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

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, more preferably 0°C or lower. The lower limit of the glass transition temperature (Tg) of the acrylic rubber is not particularly limited, but is usually -80°C or higher, preferably -60°C or higher, more preferably -40°C or higher. By setting the glass transition temperature to the above lower limit or more, better oil resistance and heat resistance can be obtained.

The content of the acrylic rubber in the acrylic rubber sheet of the present invention is appropriately selected depending on the purpose of use, but is usually 85% by weight or more, preferably 90% by weight or more, more preferably 95% by weight or more, and particularly preferably 95% by weight or more. 97% by weight or more, most preferably 98% by weight or more.

<Containing anti-aging agent>
The acrylic rubber sheet of the present invention is characterized by containing a liquid antioxidant. As the liquid anti-aging agent, any commonly used anti-aging agent can be used without particular limitation as long as it is a liquid anti-aging agent. The "liquid" of the liquid anti-aging agent is not particularly limited, but usually means that it is in a liquid form at a normal pressure of 40°C or less.

The melting point of the liquid antioxidant used is not particularly limited, but is usually 40° C. or lower, preferably 35° C. or lower, more preferably 30° C. or lower. can be remarkably improved. Although the lower limit of the melting point of the liquid anti-aging agent is not particularly limited, it is usually -40°C or higher, preferably -20°C or higher, and more preferably 0°C or higher. It is suitable for excellent heat resistance and excellent bleeding property of the liquid anti-aging agent.

The molecular weight of the liquid antioxidant to be used is not particularly limited, but is usually 100 to 800, preferably 120 to 600, more preferably 150 to 500, particularly preferably 200 to 400. It is suitable because the storage stability and heat resistance of the rubber sheet can be improved to a high degree.

The type of liquid anti-aging agent to be used is not particularly limited. anti-aging agent, quinoline anti-aging agent, hydroquinone anti-aging agent, etc. Among these, phenolic anti-aging agent is suitable because it can improve the storage stability and heat resistance of the acrylic rubber sheet to a high degree.

The structure of the liquid anti-aging agent to be used is not particularly limited, but a hindered structure is preferable because the storage stability and heat resistance of the acrylic rubber sheet can be improved to a high degree. The compound having a hindered structure is not particularly limited as long as it is a liquid antioxidant having a hindered structure, but a liquid hindered phenol antioxidant is preferred. The hindered phenol anti-aging agent refers to an agent having bulky substituents on carbon atoms on both sides of an aromatic ring carbon atom having an OH group.

（Ｒ１は、イソプロピル基又はｔ－ブチル基を示し、Ｒ２は、炭素数１～１２のアルキル基を示す。）で表されるヒンダードフェノール系老化防止剤を挙げることができる。 Suitable liquid hindered phenol anti-aging agents include, for example, general formula (1)

(R1 represents an isopropyl group or a t-butyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms).

R1 in the formula represents an isopropyl group or a t-butyl group, preferably a t-butyl group. R2 in the formula represents an alkyl group having 1 to 12 carbon atoms, preferably an alkyl group having 4 to 10 carbon atoms, more preferably an alkyl group having 6 to 10 carbon atoms.

Specific examples of the phenolic antioxidant represented by the general formula (1) include butyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, 3-(4-hydroxy-3 ,5-di-tert-butylphenyl)hexylpropionate, 3-(4-hydroxy-3,5-di-tert-butylphenyl)octylpropionate, 3-(4-hydroxy-3,5-di-tert -butylphenyl)decylpropionate, 3-(4-hydroxy-3,5-diisopropylphenyl)heptylpropionate, 3-(4-hydroxy-3,5-diisopropylphenyl)octylpropionate, 3-(4-hydroxy -3,5-diisopropylphenyl)dodecylpropionate, preferably octyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate or 3-(4-hydroxy-3, octyl 5-diisopropylphenyl)propionate, more preferably octyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate.

Examples of hindered phenol anti-aging agents other than the general formula (1) include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6 -di-t-butyl-α-dimethylamino-p-cresol and the like.

Phenolic antioxidants other than hindered phenol antioxidants include, for example, butylhydroxyanisole, styrenated phenols such as mono (or di or tri) (α-methylbenzyl) phenol, 2,2' -methylene-bis(6-α-methyl-benzyl-p-cresol), 2,2′-methylene-bis(4-methyl-6-t-butylphenol), alkylated bisphenols, 2,4-bis[(octylthio ) methyl]-6-methylphenol, 2,2′-thiobis-(4-methyl-6-t-butylphenol), 4,4′-thiobis-(6-t-butyl-o-crezo) and the like. , preferably 2,4-bis[(octylthio)methyl]-6-methylphenol.

Various anti-aging agents for rubber are already on the market. Although listed, in the present invention, among the anti-aging agents listed in the same table, those in liquid form may be used.

These liquid anti-aging agents can be used alone or in combination of two or more, and the content in the acrylic rubber sheet is not particularly limited and can be appropriately selected within the range where the effects of the present invention can be exhibited. However, the range is usually 0.001 to 15% by weight, preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, and particularly preferably 0.5 to 3% by weight. .

The acrylic rubber sheet of the present invention must contain a liquid anti-aging agent, but may contain other anti-aging agents within a range that does not impair the purpose of the present invention.

<Acrylic rubber sheet>
The acrylic rubber sheet of the present invention is characterized by being made of the above acrylic rubber, containing the anti-aging agent, and having a specific amount of gel insoluble in methyl ethyl ketone.

The thickness of the acrylic rubber sheet of the present invention is not particularly limited. , storage stability and productivity are highly balanced and suitable. In particular, when the productivity is remarkably improved and an inexpensive acrylic rubber sheet is produced, the thickness is usually in the range of 1 to 30 mm, preferably 2 to 25 mm, more preferably 3 to 15 mm, and 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 when it is usually in the range of 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm, it is particularly suitable for excellent handleability. is.

The length of the acrylic rubber sheet of the present invention is not particularly limited, but when it is usually in the range of 300 to 1200 mm, preferably 400 to 1000 mm, and more preferably 500 to 800 mm, it is particularly suitable for excellent handleability. 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, and most preferably 5% by weight, in terms of methyl ethyl ketone insolubles. When the amount is not more than % by weight, the workability is highly improved, which is preferable. The amount of gel, which is the insoluble portion of methyl ethyl ketone in the acrylic rubber veil, is related to the processability during kneading such as Banbury. There was no correlation with the gel amount of

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, and particularly preferably 0.95 to 0.95. 1.25, most preferably 1.0 to 1.2, is highly excellent in storage stability and is suitable.

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

Although the water 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, and more preferably 0.6% by weight or less. is optimized, and properties such as heat resistance and water resistance are highly excellent and suitable.

The ash content of the acrylic rubber sheet of the present invention is . Although it is not particularly limited, it is usually 0.5% by weight or less, preferably 0.3% by weight or less, more preferably 0.2% by weight or less, particularly preferably 0.15% by weight or less, and most preferably 0% by weight. When the content is 13% by weight or less, the storage stability and water resistance are excellent, which is preferable.

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, Especially preferably 0.005% by weight or more, most preferably 0.01% by weight or more, metal adhesion is suppressed and workability is excellent.

The ash content of the acrylic rubber sheet of the present invention, which provides a high balance of storage stability, water resistance and metal adhesion, is not particularly limited, but is usually 0.0001 to 0.5% by weight, preferably 0.5% by weight. 0.0005 to 0.5 wt%, more preferably 0.001 to 0.2 wt%, particularly preferably 0.005 to 0.15 wt%, most preferably 0.01 to 0.13 wt% be.

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 When the content is at least 30% by weight, preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 80% by weight or more, storage stability and water resistance are highly excellent and suitable.

The total amount of sodium and sulfur in the ash content 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, and more preferably 70% by weight as a ratio to the total ash content. % or more, particularly preferably 80% by weight or more, is highly excellent in storage stability and water resistance.

The ratio of sodium to sulfur ([Na]/[S]) in the ash content of the acrylic rubber sheet of the present invention is not particularly limited as a weight ratio, but is usually 0.4 to 2.5, preferably 0. .6 to 2, preferably 0.8 to 1.7, more preferably 1 to 1.5, the water resistance is highly excellent and suitable.

The total amount of magnesium and phosphorus in the ash content 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, in terms of the total ash content. % or more, particularly preferably 80% by weight or more, is highly excellent in storage stability and water resistance.

The ratio of magnesium to phosphorus ([Mg]/[P]) in the ash content of the acrylic rubber sheet of the present invention is not particularly limited as a weight ratio, but is usually 0.4 to 2.5, preferably 0. .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 when storage stability and water resistance are improved. Highly superior 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 2,500 to 7,000 Pa·s, and most preferably 2,700 to 5,500 Pa·s, are suitable for excellent workability, oil resistance and shape retention.

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

The ratio of the complex viscosity at 100°C ([η]100°C) to the complex viscosity at 60°C ([η]60°C) of the acrylic rubber sheet of the present invention ([η]100°C/[η]60°C) is not particularly limited, but is usually 0.5 or more, preferably 0.6 to 0.98, more preferably 0.75 to 0.95, particularly preferably 0.8 to 0.94, most preferably 0 A range of 0.83 to 0.93 is preferred because workability, oil resistance, and shape retention are well 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. It is suitable because it has a highly balanced property and strength characteristics.

<Manufacturing method of acrylic rubber sheet>
The method for producing the acrylic rubber sheet of the present invention is not particularly limited. An emulsion polymerization step of obtaining an emulsion polymerization liquid by emulsion polymerization, an antioxidant addition step of adding a liquid antioxidant to the obtained emulsion polymerization liquid, and an emulsion polymerization liquid added with a liquid antioxidant is brought into contact with the coagulation liquid. a coagulation step of producing wet crumbs by drying, a washing step of washing the produced wet crumbs, and a dewatering barrel having a dewatering slit, a drying barrel under reduced pressure, and a screw type extrusion having a die at the tip of the washed wet crumbs. dehydration, drying, and molding processes of dehydrating to a moisture content of 1 to 40% by weight in a dehydration barrel using a machine, drying to a moisture content of less than 1% by weight in a drying barrel, and extruding a sheet-shaped dry rubber from a die. It can be manufactured easily.

(Emulsion polymerization step)
In the emulsion polymerization step in the method for producing an acrylic rubber sheet of the present invention, a polymer component containing a (meth)acrylic acid ester and a reactive group-containing monomer is emulsified with water and an emulsifier, and emulsion polymerized in the presence of a polymerization catalyst. It is characterized by emulsifying an emulsion polymerization liquid with water and an emulsifier, followed by emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid.

The monomer components to be 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. Well, usually, the amount is equivalent to the monomer composition of the acrylic rubber constituting the acrylic rubber sheet.

The emulsifier used is not particularly limited, and examples thereof include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, etc., preferably anionic emulsifiers, and particularly preferably sulfate esters. salts, phosphate ester salts, most preferably phosphate ester salts.

Examples of anionic emulsifiers include, but are not limited to, salts of fatty acids such as myristic acid, palmitic acid, oleic acid and linolenic acid; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; sulfate 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. Suitable phosphate salts include, for example, sodium lauryl phosphate, potassium lauryl phosphate, polyoxyalkylene alkyl ether sodium phosphate, and the like. Suitable sulfate salts include, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, sodium laureth sulfate, sodium polyoxyethylene alkyl sulfate, sodium polyoxyethylene alkylaryl sulfate, etc. Among these, Sodium lauryl sulfate is particularly preferred. These anionic emulsifiers may be used alone or in combination of two or more.

Examples of cationic emulsifiers include alkyltrimethylammonium chloride, dialkylammonium chloride, and benzylammonium chloride.

Examples of nonionic emulsifiers include, but are not limited to, polyoxyalkylene fatty acid esters such as polyoxyethylene stearate; polyoxyalkylene alkyl ethers such as polyoxyethylene dodecyl ether; polyoxyethylenes such as polyoxyethylene nonylphenyl ether; Alkylene alkylphenol ethers; polyoxyethylene sorbitan alkyl esters and the like can be mentioned, and polyoxyalkylene alkyl ethers and polyoxyalkylene alkylphenol ethers are preferred, and polyoxyethylene alkyl ethers and polyoxyethylene alkylphenol ethers are more preferred.

These emulsifiers can be used either alone or in combination of two or more. It ranges from 1 to 5 parts by weight, more preferably from 1 to 3 parts by weight.

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

The polymerization catalyst to be used is not particularly limited as long as it is commonly used in emulsion polymerization. For example, a redox catalyst comprising a radical generator and a reducing agent can be used.

Examples of radical generators include peroxides and azo compounds, preferably peroxides. Inorganic peroxides and organic peroxides are used as peroxides.

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, para-menthane 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 , diisobutyryl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanate, t-hexyl peroxypivalate, t-butyl peroxyneodecanate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 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-hexylperoxyisopropyl monocarbonate, t-butylperoxyisopropylmonocarbonate, t-butylperoxy-2-ethylhexylmonocarbonate, 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, and benzoyl peroxide are preferred.

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

These radical generators can be used either alone or in combination of two or more. It 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 that can be used as a redox catalyst for emulsion polymerization can be used without particular limitation. In the present invention, it is particularly preferable to use at least two kinds of reducing agents. As the at least two reducing agents, for example, a combination of a metal ion compound in a reduced state and another reducing agent is suitable.

The metal ion compound in a reduced state is not particularly limited, but examples thereof include ferrous sulfate, ferrous sodium hexamethylenediaminetetraacetate, and cuprous naphthenate, among which ferrous sulfate is preferred. These metal ion compounds in a reduced state can be used alone or in combination of two or more. 01 parts by weight, preferably 0.00001 to 0.001 parts by weight, more preferably 0.00005 to 0.0005 parts by weight.

The reducing agent other than the metal ion compounds in their reduced state is not particularly limited, but for example, ascorbic acid or salts thereof such as ascorbic acid, sodium ascorbate, potassium ascorbate; erythorbic acid, sodium erythorbate, erythorbin 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 bisulfite, potassium hydrogen sulfite; sodium pyrosulfite, potassium pyrosulfite Pyrosulfites such as , sodium pyrosulfite and potassium pyrosulfite; Thiosulfates such as sodium thiosulfate and potassium thiosulfate; phosphorous acid or salts thereof; pyrophosphorous acids or salts thereof such as pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, sodium hydrogen pyrophosphite, potassium hydrogen pyrophosphite; and sodium formaldehyde sulfoxylate. Among these, ascorbic acid or its salts, sodium formaldehyde sulfoxylate and the like 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. The amount used is usually 0.001 per 100 parts by weight of the monomer component. ~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 its salt 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, more preferably 0.00001 to 0.001 parts by weight, per 100 parts by weight of the monomer component In the range of 0.00005 to 0.0005 parts by weight, the amount of ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate used is usually 0.001 to 1 part by weight per 100 parts by weight of the monomer component, The range is preferably 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 the same as that used in the emulsification of the monomer components. ~500 parts by weight, more preferably 80 to 400 parts by weight, most preferably 100 to 300 parts by weight.

The emulsion polymerization reaction may be carried out according to a conventional method, which may be a batch system, a semi-batch system or a continuous system. The polymerization temperature and polymerization time are not particularly limited, and can be appropriately selected depending on the type of polymerization initiator to be used. The polymerization temperature is generally 0 to 100°C, preferably 5 to 80°C, more preferably 10 to 50°C, and the polymerization time is generally 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 acrylic rubber sheet produced has excellent strength characteristics. Moreover, it is suitable because it has no monomer odor. A polymerization terminator may be used for terminating the polymerization.

(Antiaging agent addition step)
The anti-aging agent addition step in the method for producing an acrylic rubber sheet of the present invention is characterized by adding a liquid anti-aging agent to the emulsion polymerization liquid after the emulsion polymerization.

The liquid anti-aging agent to be used is the same as that described in the contained anti-aging agent, and the amount used may be appropriately selected so as to be the content of the acrylic rubber sheet. Usually 0.001 to 15 parts by weight, preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, particularly preferably 0.3 to 3 parts by weight, most preferably It ranges from 0.5 to 2 parts by weight.

The method of adding the liquid anti-aging agent to the emulsion polymerization liquid is not particularly limited and may be according to a conventional method. good.

(coagulation process)
The coagulation step in the method for producing an acrylic rubber sheet of the present invention is a step of bringing the emulsion polymerization liquid to which the liquid anti-aging agent is added into contact with the coagulation liquid to form water-containing crumbs.

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, more preferably 20 to 40% by weight. be.

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

Other metal salts include, for example, zinc chloride, titanium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, aluminum chloride, tin chloride, zinc nitrate, titanium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate. , aluminum nitrate, tin nitrate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate, tin sulfate, and the like.

These coagulants may be used alone or in combination of two or more. The amount used is usually 0.01 to 100 parts by weight, preferably 0.01 to 100 parts by weight, per 100 parts by weight of the monomer component. It ranges from 1 to 50 parts by weight, more preferably from 1 to 30 parts by weight. When the coagulant is in this range, the coagulation of the acrylic rubber is sufficient, and the compression set resistance and water resistance of the crosslinked acrylic rubber sheet can be highly improved, which is preferable.

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, and particularly preferably 1.5 to 5% by weight. It is preferable that the grain size of the water-containing crumbs that are sometimes generated can be uniformly concentrated in a specific region.

Although the temperature of the coagulating liquid is not particularly limited, it is usually 40° C. or higher, preferably 40 to 90° C., and more preferably 50 to 80° C., because uniform water-containing crumbs are produced.

The contact between the emulsion polymerization liquid and the coagulation liquid is not particularly limited, but may be, for example, a method of adding the emulsion polymerization liquid to the coagulation liquid being stirred, or adding the coagulation liquid to the emulsion polymerization liquid being stirred. Although any method may be used, the method of adding the emulsion polymerization liquid to the coagulating liquid being stirred makes the shape and crumb diameter of the water-containing crumbs produced uniform and converged, and greatly improves the efficiency of washing the emulsifier and coagulant. It is possible and suitable.

The stirring speed (rotational speed) of the coagulated liquid being stirred, that is, the rotating speed of the stirring blades of the stirrer, 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 400-800 rpm.

It is preferable that the number of revolutions is a number of revolutions at which the crumbs are stirred vigorously to some extent because the grain size of the water-containing crumbs to be generated can be made small and uniform. can be suppressed from being produced, and by making it equal to or less than the above upper limit, the control of the coagulation reaction can be made easier.

The peripheral speed of the coagulated liquid being stirred, that is, the speed of the outer periphery of the stirring blade of the stirring device, is not particularly limited, but vigorous stirring to a certain extent reduces the grain size of the water-containing crumbs generated and 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, most preferably 2.5 m/s or more. On the other hand, the upper limit of the peripheral 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, most preferably 20 m / s or less. This is preferable because the reaction can be easily controlled.

By setting the above conditions of 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 peripheral speed during stirring of the coagulation liquid, etc.) to a specific range, generation The shape and crumb diameter of the water-containing crumbs are uniform and bundled, and the removal of emulsifiers and coagulants during washing and dehydration is remarkably improved.

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

The washing method is not particularly limited and may be carried out according to a conventional method. For example, the produced water-containing crumbs may be mixed with a large amount of water.

The amount of water to be used is not particularly limited. A range of preferably 100 to 10,000 parts by weight, particularly preferably 150 to 5,000 parts by weight is suitable because the ash content in the acrylic rubber sheet can be effectively reduced.

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

By setting the temperature of the washing water to be equal to or higher than the above lower limit, the emulsifier and the coagulant are separated from the water-containing crumbs, thereby further improving the washing efficiency.

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

The number of washings is not particularly limited, and is usually 1 to 10 times, preferably multiple times, and more preferably 2 to 3 times. From the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber sheet, it is desirable to wash with water more often, but the shape and diameter of the water-containing crumbs should be specified and/or Alternatively, by setting the washing temperature within the above range, the number of times of washing can be significantly reduced.

(Dewatering/drying/forming process)
In the dehydration, drying, and molding steps in the method for producing an acrylic rubber sheet of the present invention, the washed water-containing crumbs are subjected to a dehydration barrel having a dehydration slit, a drying barrel under reduced pressure, and a screw type extruder having a die at the tip. After dehydrating to a moisture content of 1 to 40% by weight in a dehydration barrel, the rubber is dried to less than 1% by weight in a drying barrel, and the sheet-shaped dry rubber is extruded from a die.

In the present invention, it is preferable that free water is removed (drained) from the water-containing crumbs supplied to the screw-type extruder after washing.

Draining process In the method for producing an acrylic rubber sheet of the present invention, after the water washing process and before the dewatering/drying process, a water draining process for separating free water from the washed water-containing crumbs with a drainer can improve the dehydration efficiency. Suitable for lifting.

As the drainer, a known one can be used without particular limitation, and examples thereof include a wire mesh, a screen, an electric sieve, and the like, preferably a wire mesh and a screen.

The opening of the water drainer is not particularly limited, but is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm. It is suitable because it is small and can be drained efficiently.

The water content of the water-containing crumbs after draining, that is, the water content of the water-containing crumbs put into the dewatering/drying step is not particularly limited, but is usually 50 to 80% by weight, preferably 50 to 70% by weight, and more. It is preferably in the range of 50-60% by weight.

The temperature of the water-containing crumbs after draining, that is, the temperature of the water-containing crumbs introduced 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. ° C., particularly preferably 55 to 85 ° C., most preferably 60 to 80 ° C., the specific heat is as high as 1.5 to 2.5 KJ / kg · K like the acrylic rubber of the present invention, and the temperature is raised. It is preferable that water-containing crumbs, which are difficult to remove, can be efficiently dehydrated and dried using a screw type extruder.

Dehydration of wet crumbs (dehydration barrel)
Dewatering of the wet crumb takes place in dewatering barrels with dewatering slits. The opening of the dehydration slit may be appropriately selected according to the conditions of use, but it is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm. In addition, the loss of water-containing crumbs is small, and the water-stopped crumbs can be efficiently dewatered.

The number of dewatering barrels in the screw-type extruder is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 6, in order to dehydrate the sticky acrylic rubber. It is suitable for efficient performance.

There are two ways to remove water from the water-containing crumb in the dewatering barrel: removal in liquid form (wastewater) and removal in vapor form (exhaust steam) through the dewatering slits. Exhaust steam is defined and distinguished as preliminary drying.

When a screw-type extruder equipped with a plurality of dewatering barrels is used, it is preferable to combine drainage (dehydration) and exhaust steam (pre-drying) to efficiently remove moisture from the adhesive acrylic rubber. The screw type extruder equipped with three or more dehydrating barrels may be selected between a drainage type dehydration barrel and a steam discharge type dehydration barrel as appropriate according to the purpose of use. For less, use more drainage barrels, and for lower water content, use more steam exhaust barrels.

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

The water content after dehydration in the drainage type dehydration for squeezing out the water from the water-containing crumb is not particularly limited, but is usually 1 to 45% by weight, preferably 1 to 40% by weight, more preferably 5 to 35% by weight, especially Productivity and ash removal efficiency are highly balanced when it is preferably 10 to 35% by weight, most preferably 15 to 35% by weight.

If the sticky acrylic rubber is dehydrated using a centrifuge or the like, the acrylic rubber adheres to the dewatering slits and is hardly dehydrated (the water content is up to about 45 to 55% by weight). The use of a screw-type extruder with a dewatering slit and forcibly squeezed by a screw made it possible to reduce the water content to this extent.

In the dehydration of the water-containing crumb in the case of providing the drainage type dewatering barrel and the exhaust steam type dehydration barrel, the moisture content after dehydration in the drainage type dehydration barrel is usually 5 to 45% by weight, preferably 10 to 40% by weight, more preferably. is 15 to 35% by weight, and the moisture content after predrying in the exhaust steam type dehydration barrel is usually 1 to 30% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight.

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

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

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

The set temperature of the drying barrel may be selected as appropriate, but when it is usually in the range of 100 to 250°C, preferably 110 to 200°C, more preferably 120 to 180°C, the acrylic rubber does not burn or deteriorate. It is suitable because it enables efficient drying and reduces the amount of methyl ethyl ketone-insoluble gel in the acrylic rubber sheet.

The number of drying barrels in the screw type extruder is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 8. The degree of pressure reduction in the case of having a plurality of drying barrels may be similar to or different for all the drying barrels. When there are multiple drying barrels, the set temperature may be set to a similar temperature for all the drying barrels or may be changed. It is preferable that the temperature of method (1) is higher because the drying efficiency can be increased.

The moisture content of the dry rubber after drying is usually less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less. In the present invention, the liquid anti-aging agent and the acrylic rubber are melt-kneaded and extruded in a screw-type extruder with the moisture content of the dry rubber at this value (a state in which most of the water has been removed), thereby improving storage stability and heat resistance. An acrylic rubber sheet having highly improved properties can be produced, which is suitable. In the present invention, the acrylic rubber is melted and kneaded in a state in which most of the water is removed, thereby reducing the gel amount of the methyl ethyl ketone-insoluble portion of the acrylic rubber sheet and significantly improving the processability of the acrylic rubber sheet. preferred.

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

The dried rubber to be extruded is preferably formed into a sheet by forming a die into a substantially rectangular shape so that a dried rubber with less entrainment of air, a large specific gravity and excellent storage stability can be obtained.

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, less air is entrained (higher specific gravity). Moreover, it is suitable for excellent productivity.

Screw extruder and operating conditions The screw length (L) of the screw extruder to be used may be appropriately selected depending on the purpose of use, usually 3000 to 15000 mm, preferably 4000 to 10000 mm, more preferably 4500 ~8000 mm.

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

The ratio (L/D) between the screw length (L) and the screw diameter (D) of the screw extruder used is not particularly limited, but is usually 10 to 100, preferably 20 to 80, more The range of 30 to 60 is preferable because the moisture content can be reduced to less than 1% by weight without causing a reduction in the molecular weight of the dry rubber or burning.

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

The throughput (Q) of the screw extruder used is not particularly limited, but is usually 100 to 1,500 kg/hr, preferably 300 to 1200 kg/hr, more preferably 400 to 1000 kg/hr, most preferably 500 ~800 kg/hr.

The ratio (Q/N) of the output (Q) and the rotation speed (N) of the screw extruder used is not particularly limited, but is usually 2 to 10, preferably 3 to 8, more preferably is in the range of 4-6.

Dried rubber in sheet form The dried rubber extruded from the screw type extruder is in the form of a sheet, which is preferable because air is not entrained and the specific gravity can be increased and the storage stability is highly improved. The dry rubber sheet extruded from the screw extruder is usually cooled, cut and used as an acrylic rubber sheet.

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

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

The temperature of the dried rubber extruded from the screw extruder is not particularly limited, but is usually in the range of 100-200°C, preferably 110-180°C, more preferably 120-160°C.

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

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

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

The method of cutting the dry rubber sheet is not particularly limited, but since the acrylic rubber of the acrylic rubber sheet of the present invention has strong adhesiveness, the dry rubber sheet is cut continuously without entraining air. It is preferable to carry out after cooling.

The cutting temperature of the dry rubber sheet is not particularly limited, but is usually 60° C. or lower, preferably 55° C. or lower, and more preferably 50° C. or lower, because cuttability and productivity are highly balanced. is.

The complex viscosity ([η] 60° C.) of the dry rubber sheet 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 2,700 to 5,500 Pa·s, so that continuous cutting can be performed without entrainment of air.

The ratio ([η]100°C/[η]60°C) of the complex viscosity of the dry rubber sheet at 100°C ([η]100°C) and the complex viscosity at 60°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, and most preferably 0.83. When it is in the range of ~0.93, there is little air entrainment, and cutting and productivity are highly balanced, which is preferable.

The method for cooling the dry rubber sheet is not particularly limited, and it may be left at room temperature. Forced cooling, such as an air-cooling system under cooling, a water-spraying system, or an immersion system in which water is immersed, is preferable for increasing productivity, and air-cooling under ventilation or cooling is particularly preferable.

In the air-cooling method for sheet-like dry rubber, for example, the sheet-like dry rubber can be extruded from a screw type extruder onto a conveying machine such as a belt conveyor, and then 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 5-500m, preferably 10-200m, more preferably 20-100m. The cooling rate of the dry rubber sheet is not particularly limited, but cutting is particularly easy when it is usually 50° C./hr or higher, more preferably 100° C./hr or higher, and more preferably 150° C./hr or higher. and is suitable.

The cut length of the dry rubber sheet is not particularly limited and can be appropriately selected according to the purpose of use.

The thus-obtained acrylic rubber sheet is superior to crumb-like acrylic rubber in operability, storage stability, and heat resistance, and can be used as it is or after being laminated and baled.

<Acrylic rubber veil>
The acrylic rubber veil of the present invention is characterized by laminating the acrylic rubber sheets. The number of layers to be laminated is appropriately selected according to 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 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm, and the length is usually 300 to 1200 mm. , preferably 400 to 1000 mm, more preferably 500 to 800 mm, and a height usually in the range of 50 to 500 mm, preferably 100 to 300 mm, more preferably 150 to 250 mm.

Reactive group content, monomer composition, weight average molecular weight (Mw), ratio of z average molecular weight (Mz) to weight average molecular weight (Mw) of acrylic rubber constituting the acrylic rubber veil of the present invention (Mz/Mw ) and the glass transition temperature (Tg) are the same as the respective characteristic values of the acrylic rubber constituting the acrylic rubber sheet.

Reactive group content of the acrylic rubber veil of the present invention, liquid antioxidant content, water content, ash content, ash component content and ratio, specific gravity, methyl ethyl ketone insoluble gel amount, pH, complex viscosity at 60 ° C. ([η] 60°C), complex viscosity at 100°C ([η] 100°C), complex viscosity at 100°C ([η] 100°C) and 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 those of the acrylic rubber sheet.

The method for producing the acrylic rubber veil of the present invention is not particularly limited, but it can be easily produced by cooling the dried rubber sheet (acrylic rubber sheet) extruded from the screw extruder, cutting it, and laminating it. can.

The lamination temperature of the dry rubber sheet is not particularly limited, but it is usually 30° C. or higher, preferably 35° C. or higher, more preferably 40° C. or higher, so that the air entrained during lamination can be released. The number of layers to be laminated may be appropriately selected according to the size or weight of the acrylic rubber veil.

The thus-obtained acrylic rubber veil of the present invention is superior in operability, storage stability and water resistance as compared with the crumb-like acrylic rubber. It can be used by putting it into a mixer.

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

The filler is not particularly limited, but examples thereof include reinforcing fillers and non-reinforcing fillers, preferably reinforcing fillers.

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

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

The cross-linking agent may be appropriately selected according to the type of reactive group contained in the acrylic rubber constituting the acrylic rubber sheet or the acrylic rubber veil and the intended use. If it is not particularly limited, for example, polyvalent amine compounds such as diamine compounds, and carbonates thereof; sulfur compounds; sulfur donors; triazinethiol compounds; polyepoxy compounds; organic carboxylic acid ammonium salts; polyvalent carboxylic acid; quaternary onium salt; imidazole compound; isocyanuric acid compound; organic peroxide; triazine compound; Among these, polyvalent amine compounds, carboxylate ammonium salts, dithiocarbamic acid metal salts and triazinethiol compounds are preferable, and hexamethylenediamine carbamate, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, and benzoin. Ammonium acid 2,4,6-trimercapto-1,3,5-triazine is particularly preferred.

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

When the acrylic rubber sheet or acrylic rubber veil to be used is composed of an epoxy group-containing acrylic rubber, aliphatic polyvalent amine compounds such as hexamethylenediamine and hexamethylenediamine carbamate, and carbonates thereof as cross-linking agents; Aromatic polyvalent amine compounds such as 4′-methylenedianiline; ammonium benzoate, ammonium adipate and its carboxylic acid ammonium salts; 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; , and ammonium benzoate are more preferred.

When the acrylic rubber sheet or acrylic rubber veil to be used is composed of a halogen atom-containing acrylic rubber, it is preferable to use sulfur, a sulfur donor, or a triazinethiol compound as a cross-linking agent. Examples of sulfur donors include dipentamethylenethiuram hexasulfide and triethylthiuram disulfide. Triazine compounds include, for example, 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 cross-linking agents can be used alone or in combination of two or more. The amount to be added 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 cross-linking agent within this range, it is possible to make the cross-linked rubber product excellent in mechanical strength while ensuring sufficient rubber elasticity.

In the rubber mixture of the present invention, rubber components other than the acrylic rubber sheet or acrylic rubber veil can be used as necessary.

Other rubber components used as necessary are not particularly limited. Elastomers, styrene-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, polysiloxane-based elastomers, and the like can be mentioned. The shape of the other rubber component is not particularly limited, and may be, for example, crumb-like, sheet-like, or veil-like.

These other rubber components can be used alone or in combination of two or more. The amount of these other rubber components 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 optionally contain an anti-aging agent. 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 antioxidants such as phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; sulfur ester antioxidants such as dilauryl thiodipropionate; phenyl-α-naphthylamine, phenyl-β- naphthylamine, p-(p-toluenesulfonylamido)-diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, N,N-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p - amine-based antioxidants such as phenylenediamine and butyraldehyde-aniline condensates; imidazole-based antioxidants such as 2-mercaptobenzimidazole; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, etc. quinoline antioxidants; hydroquinone antioxidants such as 2,5-di-(t-amyl) hydroquinone; Among these, amine anti-aging agents are particularly preferred.

These anti-aging agents can be used alone or in combination of two or more. The range is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight.

The rubber mixture of the present invention contains an acrylic rubber having a reactive group contained in the acrylic rubber sheet or acrylic rubber veil of the present invention, a filler, a cross-linking agent and, if necessary, other rubber components and antioxidants, and further , If necessary, other additives commonly used in the art, such as cross-linking aids, cross-linking accelerators, cross-linking retarders, silane coupling agents, plasticizers, processing aids, lubricants, pigments, coloring agents, antistatic agents, foaming agents and the like can be optionally added. These other compounding agents can be used alone or in combination of two or more, and the amount to be compounded is appropriately selected within a range that does not impair the effects of the present invention.

<Method for producing rubber mixture>
Examples of the method for producing the rubber mixture of the present invention include a method of mixing the acrylic rubber sheet or the acrylic rubber veil of the present invention with the filler, the cross-linking agent, and the other compounding agents that can be contained as necessary. Any means conventionally used in the field of rubber processing, such as an open roll, a Banbury mixer, various kneaders, etc., can be used for this. That is, using these mixers, the acrylic rubber sheet or acrylic rubber veil, the filler, the cross-linking agent and the like can be directly mixed, preferably directly kneaded.

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 restrictions on the mixing procedure for each component, but for example, after thoroughly mixing components that are difficult to react or decompose with heat, the cross-linking agent, which is a component that easily reacts or decomposes with heat, should not react or decompose. Two-step mixing is preferred, which mixes for a short period of time at a low temperature. Specifically, it is preferable to mix the acrylic rubber sheet or the acrylic rubber veil and the filler in the first step, and then mix the cross-linking agent in the second step. Other rubber components and antioxidants are usually mixed in the first stage, the cross-linking accelerator in the second stage, and other compounding agents may be appropriately selected.

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

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

The rubber cross-linked product of the present invention is obtained by molding the rubber mixture of the present invention into a desired shape using a molding machine such as an extruder, an injection molding machine, a compressor, a roll, etc., and heating the cross-linked rubber. It can be produced by reacting and fixing the shape as a rubber crosslinked product. In this case, the cross-linking may be performed after pre-molding, or the cross-linking may be performed at the same time as the molding. The molding temperature is usually 10-200°C, preferably 25-150°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, a method used for cross-linking rubber, such as press heating, steam heating, oven heating, and hot air heating, may be appropriately selected.

The cross-linked rubber product of the present invention may be subjected to secondary cross-linking by further heating depending on the shape, size, etc. of the cross-linked rubber product. The secondary cross-linking is preferably carried out for 1 to 48 hours, although it varies depending on the heating method, cross-linking temperature, shape and the like. A heating method and a heating temperature may be appropriately selected.

The rubber cross-linked product of the present invention is a seal material for, for example, O-rings, packings, diaphragms, oil seals, shaft seals, bearing sheaths, mechanical seals, well head seals, seals for electric/electronic devices, and seals for air compression devices. A unit cell equipped with a rocker cover gasket attached to the connection between the cylinder block and the cylinder head, an oil pan gasket attached to the connection between the oil pan and the cylinder head or the transmission case, a positive electrode, an electrolyte plate and a negative electrode. Various gaskets such as fuel cell separator gaskets and hard disk drive top cover gaskets installed between a pair of sandwiched housings; cushioning materials, anti-vibration materials; wire coating materials; industrial belts; tubes and hoses; ; and the like are suitably used.

The crosslinked rubber product of the present invention can also be used as extrusion molding products and mold crosslinked products for use in automobiles, such as fuel hoses, filler neck hoses, vent hoses, paper hoses, fuel tanks such as oil hoses, etc. Air system hoses such as 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 and acrylic rubber veil>
Next, the configuration of an apparatus used for manufacturing an acrylic rubber sheet and an acrylic rubber veil according to one 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 one embodiment of the present invention. For example, an acrylic rubber manufacturing system 1 shown in FIG. 1 can be used for manufacturing the acrylic rubber sheet according to the present invention.

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

The emulsion polymerization reactor is configured to perform the emulsion polymerization process described above. Although not shown in FIG. 1, the emulsion polymerization reactor has, for example, a polymerization reactor, a temperature controller for controlling the reaction temperature, and a stirring device equipped with a motor and stirring blades. In the emulsion polymerization reactor, the monomer components for forming the acrylic rubber are mixed with water and an emulsifier, emulsified while being appropriately stirred with a stirrer, and emulsion polymerization is performed in the presence of a polymerization catalyst to form an emulsion polymerization liquid. can be obtained. The addition of the liquid anti-aging agent to the emulsion polymerization solution can be carried out directly in the emulsion polymerization reactor. The emulsion polymerization reactor may be of a batch type, a semi-batch type, or a continuous type, and may be either a tank reactor or a tubular reactor.

The coagulation device 3 shown in FIG. 1 is configured to perform the above-described coagulation process. As schematically illustrated in FIG. 1, the coagulation device 3 includes, for example, a stirring tank 30, a heating unit 31 for heating the inside of the stirring tank 30, a temperature control unit (not shown) for controlling the temperature inside the stirring tank 30, It has a stirring device 34 having a motor 32 and stirring blades 33 and a drive control unit (not shown) for controlling the rotation speed and rotation speed of the stirring blades 33 . In the coagulation device 3, the emulsion polymerization liquid obtained in the emulsion polymerization reactor is brought into contact with the coagulation liquid to be coagulated, thereby producing water-containing crumbs.

In the coagulation device 3, for example, the emulsion polymerization liquid and the coagulation liquid are brought into contact with each other by adding the emulsion polymerization liquid to the coagulation liquid being stirred. That is, the stirring tank 30 of the coagulation device 3 is filled with a coagulating liquid, and the emulsion polymerization liquid is added to and brought into contact with the coagulating liquid to solidify the emulsion polymerization liquid, thereby producing water-containing crumbs.

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 heating operation of the heating unit 31 while monitoring the temperature in the agitation vessel 30 measured by a thermometer, thereby controlling the temperature in the agitation vessel 30. It is configured. The temperature of the coagulation liquid in the stirring vessel 30 is controlled by the temperature control section so that it is usually 40°C or higher, preferably 40 to 90°C, and more preferably 50 to 80°C.

The stirring device 34 of the coagulation device 3 is configured to stir the 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 in a direction perpendicular to the rotating shaft of the motor 32 . The stirring impeller 33 can cause the solidified liquid to flow in the solidified liquid filled in the stirring tank 30 by rotating around the rotating shaft by the rotational power of the motor 32 . The shape, size, and number of the stirring blades 33 are not particularly limited.

The drive control section of the coagulation device 3 is configured to control the rotational drive of the motor 32 of the stirring device 34 to set the rotational speed and rotational speed of the stirring blades 33 of the stirring device 34 to predetermined values. The rotation of the stirring blades 33 is controlled by the drive control unit so that the stirring speed of the coagulated liquid is usually 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm, and particularly preferably 400 to 800 rpm. be done. The peripheral speed of the coagulation liquid is usually 0.5 m/s or higher, preferably 1 m/s or higher, more preferably 1.5 m/s or higher, particularly preferably 2 m/s or higher, and most preferably 2.5 m/s or higher. Rotation of the stirring blade 33 is controlled by the drive control unit so that Furthermore, the driving control unit stirs so that the upper limit of the peripheral speed of the coagulation 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 wings 33 is controlled.

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

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

The water-containing crumbs washed by the washing device 4 are supplied to a screw type extruder 5 which performs a dehydration step and a drying step. At this time, the washed wet crumbs are preferably supplied to the screw extruder 5 through a drainer 43 capable of separating free water. A wire mesh, a screen, an electric sieve, or the like can be used as the drainer 43, for example.

When the washed wet crumbs are supplied to the screw extruder 5, the temperature of the wet crumbs is preferably 40°C or higher, more preferably 60°C or higher. For example, by setting the temperature of the water used for washing in the washing device 4 to 60° C. or higher (for example, 70° C.), the temperature of the water-containing crumbs supplied to the screw extruder 5 can be maintained at 60° C. or higher. Alternatively, the wet crumbs may be heated to a temperature of 40° C. or higher, preferably 60° C. or higher when conveyed from the washing device 4 to the screw extruder 5 . As a result, it becomes possible to effectively carry out the dehydration process and the drying process, which are post-processes, and to significantly reduce the moisture content of the finally obtained dry rubber.

The screw-type extruder 5 shown in FIG. 1 is configured to perform the above-described dehydration process and drying process. Although FIG. 1 shows a screw extruder 5 as a suitable example, a centrifugal separator, a squeezer, or the like may be used as a dehydrator for performing the dehydration process, and the drying process may be performed. A hot air dryer, a reduced pressure dryer, an expander dryer, a kneader dryer, or the like may be used as a dryer for drying.

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 to discharge the molded product. Specifically, the screw-type extruder 5 includes a dehydrating barrel section 53 having a function as a dehydrator for dehydrating the water-containing crumbs washed by the washing device 4, and a dryer having a function as a dryer for drying the water-containing crumbs. A barrel portion 54 is provided, and a die 59 having a forming function of forming a wet crumb is provided on the downstream side of the screw extruder 5 .

The configuration of the screw extruder 5 will be described below with reference to FIG. FIG. 2 shows the configuration of a specific example suitable for the screw extruder 5 shown in FIG. With this screw type extruder 5, the dehydration/drying process described above can be performed favorably.

The screw extruder 5 shown in FIG. 2 is a twin-screw extrusion dryer having a pair of screws (not shown) in a barrel unit 51 . The screw extruder 5 has a drive unit 50 that drives a pair of screws in a barrel unit 51 to rotate. The drive unit 50 is attached to the upstream end (the left end in FIG. 2) of the barrel unit 51 . The screw extruder 5 also has a die 59 at the downstream end of the barrel unit 51 (the right end in FIG. 2).

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

The supply barrel section 52 is composed of two supply barrels, a first supply barrel 52a and a second supply barrel 52b.

The dewatering barrel section 53 is composed of three dewatering barrels, that is, a first dewatering barrel 53a, a second dewatering barrel 53b and a third dewatering barrel 53c.

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

Thus, the barrel unit 51 is constructed by connecting 13 divided barrels 52a-52b, 53a-53c, 54a-54h from the upstream side to the downstream side.

Further, the screw extruder 5 heats each of the barrels 52a to 52b, 53a to 53c, and 54a to 54h individually, and the water-containing crumbs in each of the barrels 52a to 52b, 53a to 53c, and 54a to 54h are predetermined. It has heating means (not shown) for heating to temperature. The heating means are provided in number corresponding to each barrel 52a-52b, 53a-53c, 54a-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 the steam distribution jackets formed in the respective barrels 52a-52b, 53a-53c, 54a-54h. It is not limited to this. Further, the screw extruder 5 has temperature control means (not shown) for controlling the set temperature of each heating means corresponding to each barrel 52a-52b, 53a-53c, 54a-54h.

The number of supply barrels, dehydration barrels, and drying barrels that constitute the respective barrel portions 52, 53, and 54 in the barrel unit 51 is not limited to the embodiment shown in FIG. The number can be set according to the water content of the wet crumbs.

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

A pair of screws in the barrel unit 51 are rotationally driven by drive means such as a motor housed in the drive unit 50 . The pair of screws extends from the upstream side to the downstream side in the barrel unit 51, and by being rotationally driven, the water-containing crumbs supplied to the supply barrel portion 52 can be mixed and conveyed downstream. It's like The pair of screws is preferably of a biaxially meshing type in which the crests and troughs are meshed with each other, whereby the dehydration efficiency and drying efficiency of the water-containing crumbs can be enhanced.

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

The feed barrel section 52 is a region for feeding wet crumbs into the barrel unit 51 . A first feed barrel 52 a of the feed barrel section 52 has a feed port 55 for feeding wet crumbs into the barrel unit 51 .

The dewatering barrel portion 53 is a region for separating and discharging a liquid (cerum water) containing a coagulant or the like from the water-containing crumb.

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

The slit width, that is, the opening of each of the dewatering slits 56a, 56b, and 56c may be appropriately selected according to the conditions of use, and is usually 0.01 to 5 mm, which reduces the loss of water-containing crumbs and reduces the loss of water-containing crumbs. It is preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm, from the viewpoint of efficient dehydration.

Moisture is removed from the water-containing crumbs in the dehydration barrels 53a to 53c of the dehydration barrel section 53 in two ways: removal in a liquid state from the dehydration slits 56a, 56b, and 56c, and removal in a vapor state. . In the dehydration barrel section 53 of the present embodiment, the case of removing moisture in liquid form is defined as drainage, and the case of removing moisture in vapor form is defined as exhaust steam.

In the dehydration barrel section 53, it is possible to efficiently reduce the moisture content of the adhesive acrylic rubber by combining drainage and exhaust steam, which is suitable. In the dehydration barrel section 53, which one of the first to third dehydration barrels 53a to 53c is used for discharging water or steam may be appropriately set according to the purpose of use. In order to reduce the amount of ash in the acrylic rubber sheet, it is preferable to increase the number of dewatering barrels for discharging water. In this case, for example, as shown in FIG. 2, the first and second dehydration barrels 53a and 53b on the upstream side are used to drain water, and the third dehydration barrel 53c on the downstream side is used to discharge steam. Further, for example, when the dehydration barrel section 53 has four dehydration barrels, it is conceivable that three dehydration barrels on the upstream side perform drainage and one dehydration barrel on the downstream side exhausts steam. On the other hand, if the moisture content is to be reduced, the number of dehydration barrels for discharging steam should be increased.

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 above dehydration/drying process. 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. , preferably 105 to 140°C, more preferably 110 to 130°C.

The drying barrel section 54 is an area for drying the dewatered wet crumbs under reduced pressure. Among the first to eighth drying barrels 54a to 54h constituting 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 It has vent ports 58a, 58b, 58c and 58d for degassing, respectively. Vent pipes (not shown) are connected to the vent ports 58a, 58b, 58c, and 58d, respectively.

A vacuum pump (not shown) is connected to the end of each vent pipe, and the inside of the drying barrel section 54 is decompressed to a predetermined pressure by the operation of these vacuum pumps. The screw extruder 5 has pressure control means (not shown) for controlling the operation of the 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 appropriately selected, but as described above, it is usually set to 1 to 50 kPa, preferably 2 to 30 kPa, more preferably 3 to 20 kPa.

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

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

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

According to the screw-type extruder 5 according to the present embodiment, water-containing crumbs of raw material acrylic rubber are extruded into sheet-like dry rubber in the following manner.

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

The wet crumbs dehydrated in the dewatering barrel section 53 are sent to the drying barrel section 54 by the rotation of the 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, and are carried downstream while generating heat and increasing the temperature. Then, the water contained in the melted acrylic rubber evaporates, and the water (steam) is discharged to the outside through vent pipes (not shown) connected to the respective vent ports 58a, 58b, 58c, and 58d.

By passing through the drying barrel section 54 as described above, the water-containing crumbs are dried and become a melt of acrylic rubber, and the acrylic rubber is supplied to the die 59 by the rotation of a pair of screws in the barrel unit 51 to form a sheet. is extruded from die 59 as dry rubber.

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

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

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

In addition, the ratio (Q/N) between the extrusion rate (Q) of the acrylic rubber and the number of revolutions (N) of the screw is not particularly limited, but is usually 1 to 20, preferably 2 to 10, more preferably 2 to 10. 3 to 8, with 4 to 6 being particularly preferred.

The cooling device 6 shown in FIG. 1 is configured to cool the dried rubber obtained through the dehydration process by the dehydrator and the drying process by the dryer. As a cooling method by the cooling device 6, it is possible to adopt various methods including an air cooling method under air blowing or cooling, a watering method of spraying water, an immersion method of immersing 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 type cooling device 60 for cooling the sheet-shaped dry rubber 10 molded into a sheet shape will be described with reference to FIG.

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

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

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

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

Although the cooling means 65 is not particularly limited, for example, it has a structure capable of blowing 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. etc.

The length of the conveyor 61 and the cooling means 65 of the transport-type cooling device 60 (the length of the portion to which the cooling air can be blown) L1 is not particularly limited, but is, for example, 10 to 100 m, preferably 20 to 50 m. . In addition, the conveying speed of the sheet-shaped dry rubber 10 in the conveying 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-shaped dry rubber 10 discharged from the die 59 of the screw extruder 5, It may be appropriately adjusted according to 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. The dry rubber sheet 10 is cooled by blowing cooling air.

The transport type cooling device 60 is not particularly limited to a configuration including one conveyor 61 and one cooling means 65 as shown in FIG. It is good also as a structure provided with the cooling means 65 of this. In that case, the total length of each of the two or more conveyors 61 and the cooling means 65 should be within the above range.

The baling device 7 shown in FIG. 1 is configured to process the dry rubber extruded from the screw extruder 5 and cooled by the cooling device 6 to produce a baled block. Although the weight and shape of the acrylic rubber bale produced by the bale forming device 7 are not particularly limited, for example, a substantially rectangular parallelepiped acrylic rubber bale weighing about 20 kg is produced.

Moreover, the sheet-like dried rubber 10 produced by the screw type 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 bale forming device 7 arranged downstream of the transport-type cooling device 60 shown in FIG. Specifically, the cutting mechanism of the bale forming device 7, for example, continuously cuts the cooled sheet-like dry rubber 10 at predetermined intervals to process it into cut sheet-like dry rubber 16 of a predetermined size. is configured as By laminating a plurality of cut sheet-like dry rubbers 16 cut into a predetermined size by a cutting mechanism, an acrylic rubber veil in which cut sheet-like dry rubbers 16 are 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 dry rubber 16 at 40° C. or higher, good air release is realized by further cooling and compression by its own weight.

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. "Parts", "%" and "ratios" in each example are by weight unless otherwise specified. Various physical properties were evaluated according to the following methods.

[Monomer composition]
Regarding the monomer composition in the acrylic rubber, the monomer composition of each monomer unit in the acrylic rubber was confirmed by H-NMR, and the activity of the reactive group remained in the acrylic rubber and each reaction. The sexual group content was confirmed by the following test method.

The content of each monomer unit in the acrylic rubber was calculated from the amount of each monomer used in the polymerization reaction and the polymerization conversion rate. Specifically, the polymerization reaction was an emulsion polymerization reaction, and the polymerization conversion rate was approximately 100% in which no unreacted monomer could be confirmed. It was assumed to be the same as the amount used for 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 method described below.
(1) The amount of carboxyl groups was calculated by dissolving an acrylic rubber sheet or acrylic rubber veil in acetone and performing potentiometric titration with a potassium hydroxide solution.
(2) The amount of epoxy groups was calculated by dissolving an acrylic rubber sheet or acrylic rubber veil in methyl ethyl ketone, adding a specified amount of hydrochloric acid to react with the epoxy groups, and titrating the amount of residual hydrochloric acid with potassium hydroxide. .
(3) The amount of chlorine was calculated by completely burning an acrylic rubber sheet or acrylic rubber veil in a combustion flask, absorbing the generated chlorine in water, and titrating with silver nitrate.

[Antiaging agent content]
The anti-aging agent content (%) in the acrylic rubber sheet or acrylic rubber veil is determined by dissolving the acrylic rubber sheet or acrylic rubber veil in tetrahydrofuran and performing gel permeation chromatography (GPC) measurement. Calculated based on the calibration curve.

[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 (ppm) of each component in the ash content of the acrylic rubber sheet or acrylic rubber veil was measured by pressing the ash content collected for the difference in the above ash content measurement against a φ20 mm titration filter paper and using a ZSX Primus (manufactured by Rigaku) to measure XRF. bottom.

[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 obtained by the following method.

About 0.2 g of an acrylic rubber sheet or acrylic rubber veil was weighed (X g), immersed in 100 ml of methyl ethyl ketone, allowed to stand at room temperature for 24 hours, and filtered through an 80-mesh wire mesh to remove insoluble matter in methyl ethyl ketone. The dry solid content (Yg) obtained by evaporating and solidifying the filtrate in which only the rubber component soluble in methyl ethyl ketone was dissolved was weighed and calculated by the following formula.
Gel amount (%) = 100 × (XY) / X

[specific gravity]
The specific gravity of the acrylic rubber sheet or acrylic rubber veil was measured in accordance with JIS K6268 Crosslinked Rubber—Method A for Density Measurement.

[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 with 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 the acrylic rubber were obtained by adding 0.05 mol/L of lithium chloride and 0.01% of 37% concentrated hydrochloric acid to dimethylformamide as a solvent. Absolute molecular weight and absolute molecular weight distribution measured by GPC-MALS method using solution. Specifically, a multi-angle laser light scattering photometer (MALS) and a differential refractometer (RI) were incorporated into a GPC (Gel Permeation Chromatography) device, and light scattering intensity and refraction of a molecular chain solution size-fractionated with the GPC device were measured. By measuring the rate difference with the elution time, the molecular weight of the solute and its content were sequentially calculated and obtained. The measurement conditions and measurement method using the GPC apparatus are as follows.
Column: 2 TSKgel α-M (φ7.8 mm × 30 cm, manufactured by Tosoh Corporation)
Temperature: Column 40°C
Flow rate: 0.8ml/mm
Sample preparation: 5 ml of solvent was added to 10 mg of sample and gently stirred at room temperature (dissolution was visually observed). Filtration was then performed using a 0.5 μm filter.
Injection Volume: 0.200ml

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

[Storage stability evaluation]
The storage stability of the rubber sample was evaluated by placing the rubber mixture of the rubber sample in a constant temperature and humidity chamber at 45°C x 80% RH for 7 days, and using the rubber sample before and after the test as a rubber mixture, using a rubber vulcanization tester (moving die rheometer MDR; (manufactured by Alpha Technology Co., Ltd.) to perform a cross-linking test for 10 minutes at 180 ° C. Calculate the change rate of the cross-linking density, which is the difference between the maximum torque (MH) and the minimum torque (ML) (MH-ML), and compare It was evaluated with an index with Example 1 as 100 (the smaller the index, the better the storage stability).

[Evaluation of workability]
The processability of the rubber sample was evaluated by putting the rubber sample into a Banbury mixer heated to 50° C., masticating for 1 minute, and then adding the compounding agent A of the rubber mixture formulation shown in Table 1 to obtain the first-stage rubber mixture. BIT (Black Incorporation Time), which is the time until the maximum torque value is exhibited after integration, was measured and evaluated with an index based on Comparative Example 1 being 100 (the smaller the index, the better the workability).

[Water resistance evaluation]
The water resistance of a rubber sample was tested by immersing a cross-linked rubber sample in distilled water at a temperature of 85°C for 100 hours in accordance with JIS K6258. It was evaluated by an index with 1 being 100 (the lower the index, the better the water resistance).

Volume change rate before and after immersion (%) = ((test piece volume after immersion - test piece volume before immersion) / test piece volume before immersion) x 100
[Evaluation of normal physical properties]
The normal physical properties of the rubber sample were evaluated according to the following criteria by measuring the breaking strength, 100% tensile stress and breaking elongation of the rubber cross-linked product of the rubber sample according to JIS K6251.
(1) Breaking strength was evaluated as ⊚ when 10 MPa or more and x when less than 10 MPa.
(2) The 100% tensile stress was evaluated as ⊚ when 5 MPa or more and x when less than 5 MPa.
(3) Elongation at break was evaluated as ⊚ when 150% or more and x when less than 150%.

[Example 1]
As shown in Table 2-1, 46 parts of pure water, 74.5 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of methoxyethyl acrylate, and monofumarate were added to a mixing vessel equipped with a homomixer. 1.5 parts of n-butyl and 1.8 parts of octyloxydioxyethylene phosphate sodium salt as an emulsifier were charged and stirred to obtain a monomer emulsion.

Then, 170 parts of pure water and 3 parts of the monomer emulsion obtained above were put into a polymerization reactor equipped with a thermometer and a stirrer, and cooled to 12° C. under a nitrogen stream. Then, 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 to the polymerization reactor over 3 hours. . After that, the reaction was continued while maintaining the temperature in the polymerization reaction at 23° C., and after confirming that the polymerization conversion reached approximately 100%, hydroquinone was added as a polymerization terminator to terminate the polymerization reaction. Then, 1 part of octyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate (Irganox 1135; manufactured by BASF) was added to obtain an emulsion polymerization liquid.

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

Next, 194 parts of hot water (70°C) was added to the coagulation tank and stirred for 15 minutes, and then water was discharged. did The washed wet crumbs were supplied to a screw type extruder 15, dehydrated and dried to extrude a dry rubber sheet 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 type cooling device directly connected to the screw type extruder 15 .

The screw extruder used in Example 1 has one feed 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 dewatering barrels are for draining and the third dewatering barrel is for venting. The operating conditions of the screw type extruder were as follows.

Water content:
- Moisture content of the wet crumb after draining in the second dewatering barrel: 20%
- Moisture content of the wet crumb after steam discharge in the third dehydration barrel: 10%
Moisture content of the wet crumb after drying in the 5th drying barrel: 0.4%
Rubber temperature:
- Temperature of the wet crumb fed to the first feed barrel: 65°C
・Temperature of rubber discharged from screw type extruder: 140°C
Set temperature for each barrel:
・First dehydration barrel: 90°C
・Second dehydration barrel: 100°C
・Third dehydration barrel: 120°C
- First drying barrel: 120°C
- Second drying barrel: 130°C
- Third drying barrel: 140°C
- Fourth drying barrel: 160°C
- 5th drying barrel: 180°C
Operating conditions:
・Diameter (D) of the screw in the barrel unit: 132 mm
・Total length of screw in barrel unit (L): 4620mm
・L/D: 35
・Rotation speed of the screw in the barrel unit: 135 rpm
・Extrusion rate of rubber from die: 700 kg/hr
・Die resin pressure: 2 MPa

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 and complex viscosity of the obtained acrylic rubber sheet (A) were measured. Such results are shown in Table 2-2.

Next, acrylic rubber veil (A) was obtained by stacking 20 parts (20 kg) of acrylic rubber sheet (A) before the temperature reached 40° C. or lower. 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.

Then, using a Banbury mixer, 100 parts of the acrylic rubber sheet (A) and compounding agent A of "Formulation 1" shown 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 veil, and the results are shown in Table 2-2.

Next, the obtained mixture was transferred to a roll at 50° C., and the compounding agent B of “Formulation 1” shown in Table 1 was compounded and mixed to obtain a rubber mixture. Before and after the storage stability test, a rubber mixture using the acrylic rubber sheet (A) was subjected to a cross-linking test to measure changes in cross-linking density (MH-ML), and the results are shown in Table 2-2.

The obtained rubber mixture was placed in a mold having a length of 15 cm, a width of 15 cm and a depth of 0.2 cm, and was pressed at 180° C. for 10 minutes under a pressure of 10 MPa for primary cross-linking. The cross-linked product was further heated in a gear oven at 180° C. for 2 hours for secondary cross-linking to obtain a sheet-like cross-linked rubber product. Then, a test piece of 3 cm×2 cm×0.2 cm was cut out from the obtained sheet-like crosslinked rubber product and evaluated for water resistance and normal physical properties, and the results are shown in Table 2-2.

[Example 2]
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 as the monomer components, and nonylphenyloxy as the emulsifier. An acrylic rubber sheet (B) and an acrylic rubber veil (B) were obtained in the same manner as in Example 1 except that sodium salt of hexaoxyethylene phosphate was used, and each characteristic was evaluated. The results for the acrylic rubber sheet (B) are shown in Table 2-2.

[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 characteristic (the compounding agent was changed to "Formulation 2") was evaluated. The results of the acrylic rubber sheet (C) are shown in Table 2-2.

[Example 4]
The temperature of the first dehydration barrel of the screw extruder is changed to 100 ° C. and the temperature of the second dehydration barrel is changed to 120 ° C. so that drainage is performed only in the first dehydration barrel, and in the first dehydration barrel 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 crumbs after drainage was changed to 30%, and each characteristic was evaluated. The results for the acrylic rubber sheet (D) are shown in Table 2-2.

[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 evaluated for each property (by changing the compounding agent to "Formulation 3"). The results for the acrylic rubber sheet (E) are shown in Table 2-2.

[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. The acrylic rubber sheet (F) and the acrylic rubber veil (F) were obtained in the same manner as in , and each property was evaluated (with the compounding agent changed to "Formulation 4"). The results for the acrylic rubber sheet (F) are shown in Table 2-2.

[Comparative Example 1]
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 were placed in a mixing vessel equipped with a homomixer. , 0.709 parts of sodium lauryl sulfate and 1.82 parts of polyoxyethylene dodecyl ether (molecular weight: 1500) as emulsifiers were charged and stirred to obtain a monomer emulsion.

Then, 170 parts of pure water and 3 parts of the monomer emulsion obtained above were put into a polymerization reactor equipped with a thermometer and a stirrer, and cooled to 12° C. under a nitrogen stream. Then, 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 to the polymerization reactor over 3 hours. . After that, the reaction was continued while maintaining the temperature in the polymerization reaction at 23° C., and after confirming that the polymerization conversion reached approximately 100%, hydroquinone was added as a polymerization terminator to terminate the polymerization reaction. Then, 3-(3,5-tert-butyl-4-hydroxyphenyl) stearyl propionate (Irganox 1076; manufactured by BASF) 1 part of 50% by weight aqueous dispersion (0.1% by weight of sodium lauryl sulfate dispersion Liquid) was added to obtain an emulsion polymerization liquid.

Next, after heating the emulsion polymerization liquid to which the antioxidant was added to 80° C., a 0.7% sodium sulfate aqueous solution (coagulating liquid) was continuously added to the emulsion polymerization liquid (rotation speed 100 rpm, peripheral speed 0.5 m / s). The water-containing crumbs were obtained by adding the water-containing crumbs to solidify the polymer and separating by filtration. 194 parts of industrial water was added to 100 parts of the resulting water-containing crumbs, and the mixture was stirred at 25°C for 5 minutes. After adding parts and stirring at 25 ° C. for 5 minutes, the water was discharged from the coagulation tank and acid cleaning was performed once, then 194 parts of pure water was added and pure water cleaning was performed once. to obtain a crumb-like acrylic rubber (G) having a water content of 0.4% by weight. Each property of the obtained crumb-like acrylic rubber (G) was evaluated and shown in Table 2-2.

[Comparative Example 2]
Performed in the same manner as in Comparative Example 1, except that the anti-aging agent added to the emulsion polymerization solution was changed to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (Nocrac CD; manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.). A crumb-like acrylic rubber (H) was obtained. Each property of the obtained crumb-like acrylic rubber (H) was evaluated and shown in Table 2-2.

From Table 2-2, it is made of acrylic rubber having a weight average molecular weight (Mw) of 100,000 to 5,000,000, which is mainly composed of (meth)acrylic acid ester, and has a gel amount of 50% by weight or less and is liquid. It can be seen that the acrylic rubber sheets (A) to (F) containing anti-aging agents are excellent in storage stability and workability, and are also excellent in normal physical properties including strength properties and water resistance (Examples 1 to 6). .

Regarding the storage stability, since the anti-aging agent content of the acrylic rubber sheets (A) to (F) is the same as that of the crumb-like acrylic rubber (G), the liquid anti-aging agent is the same as that of the acrylic rubber sheets (A) to (F). Presumably, the storage stability was remarkably improved due to the uniform fine dispersion within the interior (comparison between Examples 1 to 6 and Comparative Example 1). Further, after the storage stability test, no change in color tone was observed in the acrylic rubber sheets (A) to (H) of the present invention, but the crumb-like acrylic rubber sheets (G) to (H) of the comparative examples turned yellow. board.

With regard to workability, in the present invention, the polymerization conversion rate of emulsion polymerization is increased in order to increase the strength characteristics. However, the rapidly increased gel disappears by drying and melt kneading in a screw type extruder until it is substantially free of moisture (water content is less than 1%), and the workability, strength characteristics, and storage of acrylic rubber sheets It can be seen that the stability is highly balanced (compare Examples 1-6 with Comparative Example 1).

Regarding water resistance, it can be seen from Table 2-2 that the acrylic rubber sheets (A) to (F) of the present invention are overwhelmingly superior to the crumb-like acrylic rubbers (G) to (H) (practical Comparison between Examples 1-6 and Comparative Examples 1-2). This is because the amount of ash in the acrylic rubber sheet was reduced by squeezing out water from the water-containing crumbs to a specific water content in the dehydration process, and the use of phosphate ester salt as an emulsifier and magnesium salt as a coagulant. The water resistance of the acrylic rubber sheets (A) to (F) is improved by the fact that the ash remaining in the acrylic rubber sheet when it is dried has a large content of magnesium and phosphorus and has almost no effect on water resistance when the two are in a specific ratio. It can be seen that the properties in the normal state including strength properties, workability, and storage stability are well balanced (Examples 1 to 6).

From Table 2-2, further containing the phenol antioxidant represented by the general formula (1) of the present invention, reactive group amount, specific gravity, gel amount, glass transition temperature (Tg), pH, water content, weight Average molecular weight (Mw), ratio of z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz/Mw ), complex viscosity η at 100°C (100°C), complex viscosity η at 60°C (60°C ) and the ratio of complex viscosities at 100°C and 60°C (η100°C/η60°C) within a specific range, the acrylic rubber sheets (A) to (F) are excellent in storage stability and workability, and include strength characteristics. It can be seen that the normal physical properties and water resistance are also excellent (Examples 1 to 6). The characteristic values of the produced acrylic rubber veils (A) to (F) were the same as those of the corresponding acrylic rubber sheets (A) to (F).

1 acrylic rubber manufacturing system 3 coagulating device 4 washing device 5 screw extruder 6 cooling device 7 bale forming device

Claims (19)

It is composed of an acrylic rubber having a reactive group and a weight average molecular weight (Mw) of 100,000 to 5,000,000, mainly composed of (meth)acrylic acid ester, and having a gel amount of 10 insoluble in methyl ethyl ketone. An acrylic rubber sheet containing no more than 10% by weight of a liquid anti-aging agent. 2. The acrylic rubber sheet according to claim 1, wherein the content of the liquid antioxidant is in the range of 0.001 to 15% by weight. 3. The acrylic rubber sheet according to claim 1, wherein the liquid antioxidant has a hindered structure. 4. The acrylic rubber sheet according to any one of claims 1 to 3, wherein the liquid anti-aging agent is a phenol-based anti-aging agent. The liquid anti-aging agent has the general formula (1)

(R1 represents an isopropyl group or a t-butyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms). The acrylic rubber sheet described in . The acrylic rubber sheet according to any one of claims 1 to 5, wherein the ratio (Mz/Mw) of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) is 1.3 or more. The acrylic rubber sheet according to any one of claims 1 to 6, which has a weight average molecular weight (Mw) of 1,000,000 or more. The acrylic rubber sheet according to any one of claims 1 to 7, which has a pH of 6 or less. The acrylic rubber sheet according to any one of claims 1 to 8, which has a specific gravity of 0.7 or more. The acrylic rubber sheet according to any one of claims 1 to 9, which has an ash content of 0.5% by weight or less. A method for producing an acrylic rubber sheet according to any one of claims 1 to 10,
an emulsion polymerization step of emulsifying a monomer component containing (meth)acrylic acid ester as a main component with water and an emulsifier and performing emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid;
An anti-aging agent addition step of adding a liquid anti-aging agent to the emulsion polymerization liquid obtained;
a coagulation step of bringing an emulsion polymerization liquid containing a liquid antioxidant into contact with a coagulation liquid to form a water-containing crumb;
a washing step for washing the produced hydrous crumbs;
The washed water-containing crumbs are dehydrated in a dehydration barrel using a dehydration barrel having a dehydration slit, a drying barrel under reduced pressure, and a screw extruder having a die at the tip to a water content of 1 to 40% by weight, and then dried in a drying barrel. A method for producing an acrylic rubber sheet, comprising dewatering, drying, and forming steps of drying to a water content of less than 1% by weight and extruding a sheet-like dry rubber from a die. 12. The method for producing an acrylic rubber sheet according to claim 11, wherein the emulsion polymerization has a polymerization conversion rate of 90% by weight or more. An acrylic rubber veil formed by laminating the acrylic rubber sheet according to any one of claims 1 to 10. A method for producing an acrylic rubber veil by laminating the acrylic rubber sheet according to any one of claims 1 to 10. 15. The method for producing an acrylic rubber veil according to claim 14, wherein the acrylic rubber sheet is laminated at a temperature of 30[deg.] C. or higher. A rubber mixture obtained by mixing the acrylic rubber sheet according to any one of claims 1 to 10 or the acrylic rubber veil according to claim 13 with a reinforcing agent and a cross-linking agent. A method for producing a rubber mixture, which comprises mixing the acrylic rubber sheet according to any one of claims 1 to 10 or the acrylic rubber veil according to claim 13 with a reinforcing agent and a cross-linking agent in a mixer. A method for producing a rubber mixture comprising mixing the acrylic rubber sheet according to any one of claims 1 to 10 or the acrylic rubber veil according to claim 13 with a reinforcing agent and then mixing a cross-linking agent. A crosslinked rubber obtained by crosslinking the rubber mixture according to claim 16 .

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