JP7447488B2 - Acrylic rubber with excellent heat resistance and processability - Google Patents

Description

The present invention relates to an acrylic rubber, a method for producing the same, an acrylic rubber molded article, a rubber composition, and a crosslinked rubber product, and more specifically, an acrylic rubber with excellent heat resistance and processability, a method for producing the same, and a method for producing the acrylic rubber. The present invention relates to a molded article, a crosslinkable rubber composition containing the acrylic rubber, and a crosslinked rubber product obtained by crosslinking the same.

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

As such acrylic rubber, for example, Patent Document 1 (International Publication No. 2018/101146 pamphlet) describes a structural unit derived from an acrylic ester having an alkyl group having 1 to 8 carbon atoms and/or a structural unit having 2 to 8 carbon atoms. 45 to 89.5% by weight of structural units derived from an acrylic acid ester having an alkoxyalkyl group, 10 to 50% by weight of structural units derived from a methacrylic acid alkyl ester having an alkyl group having 3 to 16 carbon atoms, and a carboxy group. An acrylic copolymer with excellent heat resistance containing 0.5 to 5% by weight of structural units derived from crosslinkable monomers is disclosed, specifically, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate. , a monomer consisting of monoethyl fumarate, water, and polyoxyalkylene alkyl ether phosphate as an emulsifier are prepared, and sodium ascorbate and potassium persulfate are added to start an emulsion polymerization reaction at normal pressure and room temperature. The reaction was continued until the conversion rate reached 95%, and the emulsion polymerization solution, in which hydroquinone was added to stop polymerization, was coagulated with an aqueous sodium sulfate solution to produce a hydrous crumb, and the produced hydrous crumb was then washed with water and dried. It is described that an acrylic rubber with a Mooney viscosity of 38 is produced. However, this method has a problem in that the resulting acrylic rubber has poor processability.

International Publication No. 2018/101146 pamphlet

The present invention has been made in view of the actual state of the prior art, and provides an acrylic rubber that is excellent in both heat resistance and processability, a method for producing the same, an acrylic rubber molded article obtained by molding the acrylic rubber, and an acrylic rubber molded article obtained by molding the acrylic rubber. The object of the present invention is to provide a rubber composition containing the same, and a crosslinked rubber product obtained by crosslinking the same.

As a result of intensive research in view of the above-mentioned problems, the present inventors have found that the gel is composed of structural units of a specific composition including methacrylic acid ester, contains almost no amount of gel that is insoluble in a specific solvent, and has a specific range of weight average molecular weight (Mw). We have discovered that a certain acrylic rubber has significantly superior heat resistance and processability.

The present inventors also found that a water-containing crumb obtained by coagulating an emulsion polymerization liquid obtained by emulsifying a specific monomer component with an emulsifier and then coagulating it with a coagulation liquid was washed and then substantially processed using a screw extruder. It has been found that acrylic rubber with excellent heat resistance and processability can be easily obtained by melting and spinning until the water content is free and drying.

The present inventors further discovered that by forming the above acrylic rubber into a sheet or veil form, it has excellent heat resistance and processability, as well as other properties such as operability, storage stability, and water resistance. .

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

Thus, according to the present invention, 10 to 98.9% by weight of bonding units (A) derived from acrylic ester, 1 to 50% by weight of bonding units (B) derived from methacrylic ester, and 1 to 50% by weight of bonding units (B) derived from methacrylic ester, and 1 to 50% by weight of bonding units (B) derived from methacrylic ester. Consisting of 0.1 to 10% by weight of the bonding unit (C) and 0 to 30% by weight of the bonding unit (D) derived from other monomers, with a gel content of methyl ethyl ketone insoluble components of 30% by weight or less, and a weight average molecular weight. An acrylic rubber having a (Mw) in the range of 100,000 to 5,000,000 is provided.

In the acrylic rubber of the present invention, the ash content is preferably 1% by weight or less.
In the acrylic rubber of the present invention, it is preferable that the rubber is emulsion polymerized using a phosphate ester salt or a sulfuric ester salt as an emulsifier.
In the acrylic rubber of the present invention, it is preferable that the emulsion-polymerized polymer solution is coagulated by using an alkali metal salt or a Group 2 metal salt of the periodic table as a coagulant, and then dried.
The acrylic rubber of the present invention is preferably dried using a screw extruder after solidification.
In the acrylic rubber of the present invention, it is preferable that the drying using the screw extruder is performed in a substantially moisture-free state.
In the acrylic rubber of the present invention, it is preferable that the drying using the screw extruder is performed under reduced pressure.
The acrylic rubber of the present invention is preferably cooled at a cooling rate of 50° C./hr or more after drying using the screw extruder.

According to the present invention, an acrylic ester (a), a methacrylic ester (b), a reactive group-containing monomer (c), and if necessary, other copolymerizable monomers (d) An emulsion polymerization step in which a monomer component consisting of is emulsified with water and an emulsifier and then subjected to emulsion polymerization in the presence of a polymerization catalyst to obtain an emulsion polymerization solution, and a water-containing solution is obtained by bringing the obtained emulsion polymerization solution into contact with a coagulation solution. Production of acrylic rubber, including a coagulation step of producing crumbs, a washing step of washing the produced water-containing crumbs, and a drying step of drying the washed water-containing crumbs to a water content of less than 1% by weight using a screw extruder. A method is provided.

In the method for producing acrylic rubber of the present invention, the ratio (Q/N) of the extrusion amount (Q) to the rotation speed (N) of the screw extruder is preferably in the range of 2 to 10.

According to the present invention, there is also provided a sheet-like or veil-like acrylic rubber molded article made of the above-mentioned acrylic rubber.

In the acrylic rubber molded article of the present invention, it is preferable that the specific gravity is 0.8 or more.

According to the present invention, there is also provided a rubber composition comprising a rubber component containing the above acrylic rubber, a filler, and a crosslinking agent.

According to the present invention, there is further provided a crosslinked rubber product obtained by crosslinking the above rubber composition.

According to the present invention, an acrylic rubber excellent in both heat resistance and processability, an efficient manufacturing method thereof, an acrylic rubber molded article formed by molding the acrylic rubber, a rubber composition comprising the acrylic rubber, and the same. A crosslinked rubber product obtained by crosslinking is provided.

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

The acrylic rubber of the present invention contains 10 to 98.9% by weight of bonding units (A) derived from acrylic esters, 1 to 50% by weight of bonding units (B) derived from methacrylic esters, and 1 to 50% by weight of bonding units (B) derived from methacrylic esters. Consisting of 0.1 to 10% by weight of bonding units (C) and 0 to 30% by weight of bonding units (D) derived from other monomers, with a gel content of methyl ethyl ketone insoluble components of 30% by weight or less, and a weight average molecular weight. (Mw) is in the range of 100,000 to 5,000,000.

<Monomer component>
The bonding unit (A) constituting the acrylic rubber of the present invention is a bonding unit derived from an acrylic acid ester (a), and is preferably at least one bonding unit selected from the group consisting of an acrylic acid alkyl ester and an acrylic acid alkoxyalkyl ester. It is a bonding unit derived from acrylic ester of species.

The acrylic acid alkyl ester is not particularly limited, but examples thereof include acrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms, preferably acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms. More preferably, it is an acrylic acid alkyl ester having an alkyl group having 2 to 6 carbon atoms.

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

The acrylic acid alkoxyalkyl ester is not particularly limited, but examples thereof include acrylic acid alkoxyalkyl ester having an alkoxyalkyl group having 2 to 12 carbon atoms, and preferably acrylic acid alkoxyalkyl ester having an alkoxyalkyl group having 2 to 8 carbon atoms. acrylic acid alkoxyalkyl ester having an alkoxyalkyl group having 2 to 6 carbon atoms, more preferably an acrylic acid alkoxy ester having an alkoxyalkyl group having 2 to 6 carbon atoms.

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

These bonding units (A) derived from acrylic acid esters can be used alone or in combination of two or more, and the bonding amount in the acrylic rubber is 10 to 98.9% by weight, preferably 32 to 97.9% by weight. 7% by weight, more preferably 50 to 96.5% by weight, particularly preferably 62 to 94% by weight. If the amount of bonding unit (A) in the acrylic rubber is too small, weather resistance, heat resistance, and oil resistance may be reduced, and if it is too large, strength properties and compression set resistance may be reduced. Yes, it's not good.

The bonding unit (B) constituting the acrylic rubber of the present invention is a bonding unit derived from methacrylic acid ester (b).

The methacrylic acid ester (b) is not particularly limited, and preferable examples include at least one methacrylic ester selected from the group consisting of methacrylic acid alkyl esters and methacrylic acid alkyl esters. Alkyl esters are preferred.

Examples of methacrylic acid alkyl esters include methacrylic acid alkyl esters having an alkyl group having 1 to 14 carbon atoms, preferably methacrylic acid alkyl esters having an alkyl group having 2 to 8 carbon atoms, and more preferably carbon methacrylic acid alkyl esters. It is an alkyl methacrylate ester having 2 to 6 alkyl groups.

Specific examples of methacrylic acid alkyl esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, Examples include cyclohexyl methacrylate, octyl methacrylate, dodecyl methacrylate, isotridecyl methacrylate, etc., preferably ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, octyl methacrylate, more preferably ethyl methacrylate. , n-butyl methacrylate.

Examples of methacrylic acid alkoxyalkyl esters include methacrylic acid alkoxyalkyl esters having an alkoxyalkyl group having 2 to 14 carbon atoms, and preferably methacrylic acid alkoxyalkyl esters having an alkoxyalkyl group having 2 to 8 carbon atoms. More preferably, it is a methacrylic acid alkoxyalkyl ester having an alkoxyalkyl group having 2 to 6 carbon atoms.

Specific examples of alkoxyalkyl methacrylates include methoxymethyl methacrylate, methoxyethyl methacrylate, methoxypropyl methacrylate, methoxybutyl methacrylate, ethoxymethyl methacrylate, ethoxyethyl methacrylate, propoxyethyl methacrylate, and butoxyethyl methacrylate. Examples include. Among these, methoxyethyl methacrylate, ethoxyethyl methacrylate, ethoxymethyl methacrylate, ethoxyethyl methacrylate and the like are preferred, and methoxyethyl methacrylate and ethoxyethyl methacrylate are more preferred.

These bonding units (B) derived from methacrylic acid esters can be used alone or in combination of two or more, and the bonding amount in the acrylic rubber is 1 to 50% by weight, preferably 2 to 40% by weight, It is more preferably in the range of 3 to 30% by weight, particularly preferably in the range of 5 to 25% by weight.

The bonding unit (C) constituting the acrylic rubber of the present invention is a bonding unit derived from the reactive group-containing monomer (c).

The reactive group-containing monomer (c) is not particularly limited, but includes, for example, a monomer having at least one functional group selected from the group consisting of a carboxyl group, an epoxy group, and a halogen group. A monomer having a carboxyl group or an epoxy group is preferable, and a monomer having a carboxyl group is particularly preferable.

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

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

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

The ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, but it is usually an ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and an alkyl monoester having 1 to 12 carbon atoms, preferably 4 to 6 carbon atoms. An ethylenically unsaturated dicarboxylic acid and an alkyl monoester having 2 to 8 carbon atoms, more preferably an alkyl monoester having 2 to 6 carbon atoms of 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. Butenedionic acid monoalkyl esters such as monocyclohexyl acid, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate; itaconic acid such as monomethyl itaconate, monoethyl itaconate, mono n-butyl itaconate, monocyclohexyl itaconate Monoalkyl ester; etc., preferably mono-n-butyl fumarate and mono-n-butyl maleate, particularly preferably mono-n-butyl fumarate.

Examples of the monomer having an epoxy group include epoxy group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate; epoxy group-containing vinyl ethers such as allyl glycidyl ether and vinyl glycidyl ether; and the like. Note that "(meth)acrylic acid" as used herein is used as a generic term for acrylic acid and/or methacrylic acid, and the same applies below.

Examples of monomers having a halogen group include unsaturated alcohol esters of halogen-containing saturated carboxylic acids, (meth)acrylic acid haloalkyl esters, (meth)acrylic acid haloacyloxyalkyl esters, and (meth)acrylic acid (haloacetylcarbamoyl esters). Examples include oxy)alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers.

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

The bonding units (C) derived from these reactive group-containing monomers can be used alone or in combination of two or more, and the bonding amount in the acrylic rubber is 0.1 to 10% by weight, preferably It ranges from 0.3 to 8% by weight, more preferably from 0.5 to 5% by weight, particularly preferably from 1 to 3% by weight.

The bonding unit (D) constituting the acrylic rubber of the present invention is a bonding unit derived from another monomer (d) that is copolymerized as necessary.

Other monomers (d) are not particularly limited as long as they are other than the above monomers (a), (b), and (c) and can be copolymerized with these monomers, such as aromatic vinyl, ethylene, etc. Examples include unsaturated nitriles, acrylamide monomers, and other olefin monomers. Examples of the aromatic vinyl include styrene, α-methylstyrene, and divinylbenzene. Examples of ethylenically unsaturated nitriles include acrylonitrile and methacrylonitrile. Examples of the acrylamide monomer include acrylamide and methacrylamide. Examples of other olefinic monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, and the like.

These bonding units (D) derived from other monomers can be used alone or in combination of two or more, and the bonding amount in the acrylic rubber is 0 to 30% by weight, preferably 0 to 20% by weight. %, more preferably from 0 to 15% by weight, particularly preferably from 0 to 10% by weight. Therefore, some of the acrylic rubbers of the present invention do not contain the bonding unit (D) derived from other monomers, while others contain the bonding unit (D) within the above range. d) is not used.

<Acrylic rubber>
The acrylic rubber of the present invention comprises a bonding unit (A) derived from the above acrylic ester, a bonding unit (B) derived from a methacrylic ester, a bonding unit (C) derived from a reactive group-containing monomer, and, if necessary, Consisting of bonding units (D) derived from other monomers, the proportion of each bonding unit (A) is 10 to 98.9% by weight, preferably 32 to 97.7% by weight, more preferably 50 to 98.9% by weight. 96.5% by weight, particularly preferably from 62 to 94% by weight, and the bonding unit (B) is from 1 to 50% by weight, preferably from 2 to 40% by weight, more preferably from 3 to 30% by weight, especially It is preferably in the range of 5 to 25% by weight, and the bonding unit (C) is 0.1 to 10% by weight, preferably 0.3 to 8% by weight, more preferably 0.5 to 5% by weight, particularly preferably is in the range of 1 to 3% by weight, and the bonding unit (D) is in the range of 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. range. That is, the acrylic rubber of the present invention is a copolymer that contains each of the above-mentioned bonding units in the above-mentioned specific weight proportions, and the total of each bonding unit is 100% by weight. When the mer bond unit is within this range, it is preferable to form a crosslinked product of acrylic rubber because heat resistance, water resistance, and compression set resistance can be highly balanced.

The content of reactive groups in the acrylic rubber of the present invention is not particularly limited and may be appropriately selected from among the proportions of bonding units derived from the above-mentioned reactive group-containing monomers, and is the weight proportion of the reactive groups themselves. Processability is usually in the range of 0.001 to 5% by weight, preferably 0.01 to 3% by weight, more preferably 0.05 to 1% by weight, particularly preferably 0.1 to 0.5% by weight. It is suitable because properties such as strength, compression set resistance, oil resistance, cold resistance, and water resistance are highly balanced.

The amount of gel in the acrylic rubber of the present invention is 30% by weight or less, preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, and most preferably 5% by weight, based on the insoluble content of methyl ethyl ketone. % or less, the processability of the acrylic rubber is highly improved, which is preferable.

The total ash content in the acrylic rubber of the present invention is not particularly limited, but is usually 1% by weight, preferably 0.5% by weight or less, more preferably 0.3% by weight or less, particularly preferably 0.2% by weight. % or less, most preferably 0.15% by weight or less, and when the total ash content is within this range, the water resistance as an acrylic rubber is particularly excellent and is suitable.

The lower limit of the total ash content in the acrylic rubber of the present invention is not particularly limited, but is usually 0.0001% by weight or more, preferably 0.0005% by weight or more, more preferably 0.001% by weight or more. , particularly preferably 0.005% by weight or more, most preferably 0.01% by weight or more, since the metal adhesion of the acrylic rubber is reduced and workability is excellent.

Therefore, the total ash content at which the water resistance and metal adhesion resistance of the acrylic rubber of the present invention are highly balanced is usually 0.0001 to 1% by weight, preferably 0.0005 to 0.5% by weight, or more. Preferably it ranges from 0.001 to 0.3% by weight, particularly preferably from 0.005 to 0.2% by weight and most preferably from 0.01 to 0.15% by weight.

When the total amount of magnesium and phosphorus in the ash in the acrylic rubber of the present invention accounts for 60% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more of the total ash, the water resistance of the acrylic rubber It is suitable because it has a high degree of properties.

The glass transition temperature (Tg) of the acrylic rubber of the present invention is not particularly limited, but is usually 20°C or lower, preferably 10°C or lower, and more preferably 0°C.

The pH of the acrylic rubber of the present invention is not particularly limited, but is usually 7 or less, preferably 6 or less, more preferably 2 to 6, particularly preferably 2.5 to 5.5, and most preferably 3 to 5. The range is good, and storage stability is highly improved when it is within this range, which is preferable.

The water content of the acrylic rubber of the present invention is usually less than 1% by weight, preferably 0.8% by weight or less, and more preferably 0.6% by weight or less, since the scorch properties can be optimized.

The Mooney viscosity (ML1+4, 100°C) of the acrylic rubber of the present invention is in the range of 10 to 150, preferably 20 to 100, more preferably 25 to 80.

The weight average molecular weight (Mw) of the acrylic rubber of the present invention is an absolute molecular weight measured by GPC-MALS, and is 100,000 to 5,000,000, preferably 500,000 to 4,000,000, more preferably 700,000 to 3,000,000, most preferably 1,000,000 to 2,500,000, when the acrylic rubber has high processability, strength properties, and compression set resistance when mixed. This is preferable because it is well-balanced.

The ratio (Mw/Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic rubber of the present invention is not particularly limited, but is usually 1 in the absolute molecular weight distribution measured by GPC-MALS. A range of .1 to 8, preferably 1.2 to 7, more preferably 1.4 to 6 is preferable because the processability, strength characteristics, and compression set resistance of the acrylic rubber are highly balanced. be.

<Method for manufacturing acrylic rubber>
The method for producing the acrylic rubber is not particularly limited, but includes, for example, an acrylic ester (a), a methacrylic ester (b), a reactive group-containing monomer (c), and, if necessary, a co-producer. An emulsion polymerization step in which a monomer component consisting of another polymerizable monomer (d) is emulsified with water and an emulsifier, and then emulsion polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid;
a coagulation step of bringing the obtained emulsion polymerization liquid into contact with a coagulation liquid to produce water-containing crumb;
a cleaning step of cleaning the generated water-containing crumb;
a drying step of drying the washed water-containing crumb using a screw extruder until the water content is less than 1% by weight;
It can be easily manufactured using a manufacturing method including

Hereinafter, embodiments of each of the above steps will be described.

(Emulsion polymerization process)
In the emulsion polymerization step in the method for producing acrylic rubber of the present invention, an acrylic ester (a), a methacrylic ester (b), a reactive group-containing monomer (c), and other copolymerizable monomers as necessary. The method is characterized in that a monomer component consisting of monomer (d) is emulsified with water and an emulsifier, and then emulsion polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization solution.

The monomer components (a) to (d) used in the emulsion polymerization process of acrylic rubber are the examples and preferred ranges of monomer components corresponding to the acrylic rubber bonding units (A) to (D) already mentioned. It's the same. The amounts of the monomer components to be used are also as described above, and in the emulsion polymerization step, each monomer may be appropriately selected so as to achieve the above composition of the acrylic rubber of the present invention.

The emulsifier used as an emulsifier in the emulsion polymerization step is not particularly limited as long as it is used in emulsion polymerization, but examples include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, etc., and preferably They are anionic emulsifiers and nonionic emulsifiers, and more preferably anionic emulsifiers.

Examples of anionic emulsifiers include salts of fatty acids such as myristic acid, palmitic acid, oleic acid, and linolenic acid; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; sulfuric ester salts such as sodium lauryl sulfate, and octyloxydioxy Examples include phosphate ester salts such as sodium ethylene phosphate, alkyl sulfosuccinates, and the like. Among these anionic emulsifiers, sulfate ester salts and phosphate ester salts are preferred.

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

Examples of nonionic emulsifiers include polyoxyalkylene fatty acid esters such as polyoxyethylene stearate; polyoxyalkylene alkyl ethers such as polyoxyethylene dodecyl ether; polyoxyalkylene alkyl phenol ethers such as polyoxyethylene nonylphenyl ether; Examples include oxyethylene sorbitan alkyl ester, polyoxyalkylene alkyl ether and polyoxyalkylene alkylphenol ether are preferred, and polyoxyethylene alkyl ether and polyoxyethylene alkylphenol ether are more preferred.

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

The mixing method (mixing method) of the monomer components, water, and emulsifier may follow a conventional method, for example, a method of stirring the monomer, emulsifier, and water using a stirrer such as a homogenizer or a disc turbine. Examples include. The amount of water used is usually 1 to 1,000 parts by weight, preferably 5 to 500 parts by weight, more preferably 4 to 300 parts by weight, particularly preferably 3 to 150 parts by weight, per 100 parts by weight of the monomer component. parts, most preferably in the range of 20 to 80 parts by weight.

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

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

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

The organic peroxide is not particularly limited as long as it is used in emulsion polymerization of acrylic rubber, etc. For example, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl) ) propane, 1-di-(t-hexylperoxy)cyclohexane, 1,1-di-(t-butylperoxy)cyclohexane, 4,4-di-(t-butylperoxy)n-butyl valerate, 2,2-di-(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide, 1,1,3,3 -Tetraethylbutyl hydroperoxide, t-butylcumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, disuccinic acid peroxide, dibenzoyl peroxide, di(3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) Peroxide, diisobutyryl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetra Methylbutylperoxyneodecanate, t-hexylperoxypivalate, t-butylperoxyneodecanate, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5 -di(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate, t-hexylperoxy-2-ethylhexanate, t-butylperoxy -3,5,5-trimethylhexanate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2, 5-di(benzoylperoxy)hexane, t-butylperoxyacetate, t-hexylperoxybenzoate, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane Among these, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide and the like are preferred.

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

These radical generators can be used alone or in combination of two or more, and the amount used is usually 0.0001 to 5 parts by weight, preferably 0.0001 to 5 parts by weight, based on 100 parts by weight of the monomer component. The amount ranges from 0.005 to 1 part by weight, more preferably from 0.001 to 0.5 part by weight.

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

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

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

These reducing agents other than metal ion compounds in a reduced state can be used alone or in combination of two or more, and the amount used is usually 0.001 parts by weight per 100 parts by weight of the monomer components. ~1 part by weight, preferably 0.005 to 0.5 part by weight, more preferably 0.01 to 0.1 part by weight.

A preferred combination of a metal ion compound in a reduced state and another reducing agent is a combination of ferrous sulfate and ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate, more preferably a combination of ferrous sulfate and ascorbic acid or a salt thereof and/or sodium formaldehyde sulfoxylate. A combination of ascorbate and/or sodium formaldehyde sulfoxylate, most preferably a combination of ferrous sulfate and ascorbate. The amount of ferrous sulfate used at this time is usually 0.000001 to 0.01 parts by weight, preferably 0.00001 to 0.001 parts by weight, and more preferably 0. The amount of ascorbic acid or its salt and/or sodium formaldehyde sulfoxylate used is usually 0.001 to 1 part by weight, preferably 0.001 to 1 part by weight, per 100 parts by weight of both components. The amount ranges from 0.005 to 0.5 parts by weight, more preferably from 0.01 to 0.1 parts by weight.

The amount of water used in the emulsion polymerization reaction may be just the amount used during emulsification of the monomer components, but it is usually 10 to 1,000 parts by weight, preferably 10 to 1,000 parts by weight, based on 100 parts by weight of the monomer components used in the polymerization. The amount is adjusted to be in the range of 50 to 500 parts by weight, more preferably 80 to 400 parts by weight, and most preferably 100 to 300 parts by weight.

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

The polymerization conversion rate of the emulsion polymerization reaction is not particularly limited, but is usually 80% by weight or more, preferably 90% by weight or more, more preferably 95% by weight or more, and the acrylic rubber produced at this time has poor strength properties. It is excellent and has no monomer odor, making it suitable. A polymerization terminator may be used to terminate the polymerization.

(solidification process)
The coagulation step in the method for producing acrylic rubber of the present invention is a step of bringing the emulsion polymerization solution obtained in the above-mentioned emulsion polymerization step into contact with the coagulation solution to produce water-containing crumb.

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

Although there are no particular limitations on the coagulant used in the coagulation liquid, metal salts are usually used. Examples of the metal salt include alkali metal salts, salts of metals from group 2 of the periodic table, and other metal salts, and preferably alkali metal salts and salts of metals from group 2 of the periodic table.

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

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

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

These coagulants can be used alone or in combination of two or more, and the amount used is usually 0.01 to 100 parts by weight, preferably 0.1 parts by weight, per 100 parts by weight of the monomer component. -50 parts by weight, more preferably 1-30 parts by weight. When the coagulant is in this range, it is possible to sufficiently coagulate the acrylic rubber while highly improving compression set resistance and water resistance when the acrylic rubber is crosslinked.

When the coagulant concentration of the coagulating liquid used is usually in the range of 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, the particles of the water-containing crumb to be produced are This is preferable because the diameter can be uniform and focused on a specific area.

The temperature of the coagulating liquid used is not particularly limited, but it is preferable that it is usually 40° C. or higher, preferably 40 to 90° C., more preferably 50 to 80° C., since a uniform water-containing crumb will be produced.

In the method for producing acrylic rubber of the present invention, the contact between the emulsion polymerization liquid and the coagulation liquid in the coagulation step is carried out by adding the emulsion polymerization liquid to the stirring coagulation liquid, or adding the coagulation liquid to the emulsion polymerization liquid. There are several methods, but when the emulsion polymerization solution is added to the coagulating solution while stirring, it suppresses the generation of extremely large and fine water-containing crumbs, and improves the cleaning efficiency of the emulsifier and coagulant for the water-containing crumbs that are generated. This is suitable because it can significantly improve the performance.

The stirring speed (stirring number) of the coagulated liquid being stirred is expressed by the number of rotations per minute of the stirring device installed in the coagulation tank (specifically, the number of rotations of the stirring blade), but the When adding to the coagulation tank, it is preferable to stir it vigorously to a certain extent in order to make the size of the water-containing crumb particles small and uniform. The range is 1,000 rpm, more preferably 300 to 900 rpm, particularly preferably 350 to 850 rpm, and most preferably 400 to 800 rpm. If the stirring speed (rotation speed) of the coagulation liquid is too low, large crumb particles and small crumb particle sizes will be produced, and if it is too high, it will be difficult to control the coagulation reaction, so both Undesirable.

Additionally, the circumferential speed of the coagulated liquid being stirred is expressed by the speed of the outer circumference of the stirring blade of the above-mentioned stirring device. This is preferable because the crumb particle size can be made small and uniform, and therefore it is appropriate that the circumferential velocity of the coagulating liquid in the coagulating tank is at least 0.5 m/s or more. When this peripheral speed is 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, especially 2.5 m/s or more, the cleaning step This method is suitable because it can produce a hydrated crumb having a crumb shape and crumb diameter that allows for excellent removability of coagulants and emulsifiers in the dehydration process.

The upper limit of the peripheral speed of the coagulated liquid being stirred is not particularly limited, but is usually 30 m/s or less, preferably 25 m/s or less, more preferably 20 m/s or less, particularly preferably 15 m/s or less. It is preferable that the coagulation reaction be easily controlled at certain times.

In the acrylic rubber manufacturing method of the present invention, by appropriately selecting the above-mentioned conditions for the coagulation reaction (contact method, solid content concentration of the emulsion polymerization liquid, concentration of the coagulation liquid, temperature, number of rotations, circumferential speed, etc.), it is possible to The crumb shape and crumb diameter are uniform and concentrated, and the removal efficiency of the emulsifier and coagulant in the water-containing crumb in the washing step and dehydration step is significantly improved, which is preferable.

In this way, by adjusting the particle size and particle size distribution of the hydrous crumbs produced during acrylic rubber production to a specific range, the removal efficiency of emulsifiers and coagulants from the hydrous crumbs during washing and dehydration has been significantly improved. can.

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

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

The amount of water added for washing is not particularly limited, but the amount per water washing is usually 50 parts by weight or more, preferably 50 to 15 parts by weight, based on 100 parts by weight of the monomer components charged by emulsion polymerization. 000 parts by weight, more preferably 100 to 10,000 parts by weight, even more preferably 500 to 5,000 parts by weight, since the ash content in the acrylic rubber can be effectively reduced. be.

The temperature of the water used is not particularly limited, but it is preferable to use warm water, usually 40°C or higher, preferably 40 to 100°C, more preferably 50 to 90°C, especially 60 to 80°C. It is ideal for dramatically increasing cleaning efficiency. By setting the temperature of the hot water used to be equal to or higher than the above-mentioned lower limit, the emulsifier and coagulant are released from the water-containing crumb, and the cleaning efficiency is further improved.

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

The number of times of washing (washing with water) in the washing step is also not particularly limited, and is usually 1 to 10 times, preferably 1 to 5 times, and more preferably 2 to 3 times. In addition, from the viewpoint of reducing the amount of coagulant remaining in the acrylic rubber finally obtained, it is desirable to wash with water more often, but as mentioned above, the shape of the hydrous crumb and the diameter of the hydrous crumb should be set within a specific range. By setting the cleaning temperature and/or the cleaning temperature within the above range, the number of times of water washing can be significantly reduced.

(drying process)
The drying step in the method for producing acrylic rubber of the present invention is a step of drying the washed water-containing crumb using a screw extruder to a water content of less than 1% by weight.

There are no particular limitations on the screw type extruder used, but it is equipped with a dehydration barrel with a dehydration slit, a drying barrel that dries under reduced pressure, and a die at the tip, and can dehydrate, dry, and mold hydrous crumbs all at once. This is preferable because it can significantly improve processability without impairing the heat resistance and various properties of acrylic rubber.

Dehydration and drying in the dehydration barrel section Dehydration of the water-containing crumb is performed in a dehydration barrel provided in a screw type extruder and having a dehydration slit. The opening of the dehydration slit may be selected as appropriate depending on the conditions of use, but is usually in the range of 0.01 to 5 mm, preferably 0.1 to 1 mm, and more preferably 0.2 to 0.6 mm. In addition, it is suitable because there is little loss of water-containing crumbs and the water-containing crumbs can be dehydrated efficiently.

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

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

When using a screw extruder equipped with multiple dehydration barrels, it is especially effective because dehydration and water content reduction of sticky acrylic rubber can be efficiently carried out by combining waste water (dehydration) and exhaust steam (pre-drying). suitable. In a screw type extruder equipped with three or more dehydration barrels, whether each dehydration barrel is a drain type dehydration barrel or an exhaust steam type dehydration barrel may be appropriately selected depending on the intended use of the acrylic rubber. To reduce the amount of ash in normally produced rubber, increase the number of drain-type barrels.For example, if there are three dewatering barrels, use two drain-type barrels, and if there are four dewatering barrels, use three drain-type barrels. Please select as appropriate.

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

The water content of the water-containing crumb after dehydration, that is, the water content after passing through the drainage type barrel, is not particularly limited, but is usually 1 to 50% by weight, preferably 3 to 40% by weight, more preferably 5 to 35% by weight, most preferably Preferably, the amount is 10 to 35% by weight, since the emulsifier and coagulant can be efficiently removed. When removing emulsifiers and coagulants and reducing water content efficiently using a screw extruder, the water content after dehydration is 5 to 40% by weight, preferably 10 to 40% by weight, more preferably 15 to 35% by weight. % by weight.

When dehydrating sticky acrylic rubber with the above specific composition and crosslinkable groups using a centrifuge, etc., the acrylic rubber adheres to the dehydration slit, making it almost impossible to dehydrate it (the water content is approximately 45 to In the present invention, by using a screw type extruder equipped with a dehydration barrel that has a dehydration slit and is forcibly squeezed by a screw, the water content can be efficiently reduced to less than that. Therefore, it is particularly suitable.

The moisture content of the hydrous crumb pre-dried in an exhaust steam dehydration barrel after the above dehydration is usually 1 to 30% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight.

Drying in a Drying Barrel The hydrous crumbs dehydrated and dried in the dehydrating barrel described above are further dried in a drying barrel under reduced pressure provided on the downstream side (extrusion side) of the same screw type extruder.

The degree of vacuum inside the drying barrel may be selected as appropriate, but it is usually 1 to 50 kPa, preferably 2 to 30 kPa, more preferably 3 to 20 kPa, which is suitable for efficiently drying the water-containing crumbs.

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

The number of drying barrels in the screw extruder is not particularly limited, but is usually plural, preferably 2 to 10, more preferably 3 to 8. When there is a plurality of drying barrels, the degree of vacuum may be similar to that of all the drying barrels, or may be varied. When having multiple drying barrels, the set temperature may be set to a similar temperature for all drying barrels or may be changed, but the temperature at the discharge section (closer to the die) may be higher than the temperature at the inlet section (closer to the dehydration barrel). It is preferable to raise the temperature of the first method since drying efficiency can be increased.

The water content of the acrylic rubber crumb after drying in the drying barrel section is usually less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.6% by weight. In the present invention, in particular, melt-extruding the acrylic rubber in a screw extruder with the water content at this value (almost all water has been removed) reduces the gel amount of methyl ethyl ketone insoluble components of the acrylic rubber. This is suitable because it can significantly improve the processability of acrylic rubber.

Shape of acrylic rubber (die part)
The acrylic rubber dehydrated and dried in the screw parts of the dehydration barrel and drying barrel is sent to a rectifying die part without a screw, which is provided near the tip of the screw type extruder. A breaker plate and a wire mesh may or may not be provided between the screw part and the die part.

The acrylic rubber extruded from the die part of a screw type extruder has various shapes such as granules, pellets, columns, round rods, and sheets depending on the shape of the nozzle of the die.

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

Operating conditions of screw extruder The screw length (L) of the screw extruder used may be selected appropriately depending on the purpose of use, but is usually 3,000 to 15,000 mm, preferably 4,000 to 15,000 mm. The range is 10,000 mm, more preferably 4,500 to 8,000 mm.

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

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

The rotation speed (N) of the screw type extruder used may be appropriately selected depending on various conditions, but is usually 10 to 1,000 rpm, preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably It is preferable that the speed is 120 to 300 rpm because the water content and gel amount of the acrylic rubber can be efficiently reduced.

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

The ratio (Q/N) between the extrusion amount (Q) and the rotation speed (N) of the screw extruder used is not particularly limited, but is usually 1 to 20, preferably 2 to 10, more preferably When the value is in the range of 3 to 8, particularly preferably 4 to 6, the adhesive acrylic rubber can be dehydrated, dried, and molded efficiently, and the acrylic rubber can be improved in terms of heat resistance, processability, storage stability, etc. The properties are highly balanced and suitable.

As described above, according to the method for producing acrylic rubber of the present invention, 10 to 98.9% by weight of the bonding unit (A) derived from the above-mentioned acrylic ester, and 1 to 50% by weight of the bonding unit (B) derived from the methacrylic ester. %, bonding units derived from reactive group-containing monomers (C) 0.1 to 10% by weight and bonding units derived from other monomers (D) 0 to 30% by weight, and the gel contains methyl ethyl ketone insoluble portions. It is possible to efficiently produce acrylic rubber in which the amount is 30% by weight or less and the weight average molecular weight (Mw) is in the range of 100,000 to 5,000,000.

<Acrylic rubber molded body>
(Sheet-like or veil-like acrylic rubber molded product)
The acrylic rubber molded article of the present invention is characterized in that it is made of the above-mentioned acrylic rubber and is in the form of a sheet or a veil.

The specific gravity of the sheet-like or veil-like acrylic rubber molded article of the present invention is not particularly limited, but is usually 0.7 or more, preferably 0.8 or more, more preferably 0.9 or more, particularly preferably 0. 95 or more, most preferably 1.0 or more, particularly 0.7 to 1.5, preferably 0.8 to 1.4, more preferably 0.9 to 1.3, particularly preferably 0.95 to 1.25, most preferably in the range of 1.0 to 1.2, as storage stability is highly excellent and suitable.

The pH of the sheet-like or veil-like acrylic rubber molded article of the present invention is not particularly limited, but is usually 7 or less, preferably 6 or less, more preferably 2 to 6, particularly preferably 2.5 to 5.5. , most preferably in the range of 3 to 5, as storage stability is highly improved.

The complex viscosity ([η] 60°C) of the sheet-like or veil-like acrylic rubber molded article 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, most preferably 2,700 to 5,500 Pa・s for excellent workability, oil resistance, and shape retention. suitable.

The complex viscosity at 100°C ([η] 100°C) of the sheet-like or veil-like acrylic rubber molded article of the present invention is not particularly limited, but is usually 1,500 to 6,000 Pa·s, preferably is in the range of 2,000 to 5,000 Pa·s, more preferably 2,500 to 4,000 Pa·s, and most preferably 2,500 to 3,500 Pa·s. It has excellent retention properties and is suitable.

The ratio of the complex viscosity at 100°C ([η] 100°C) to the complex viscosity at 60°C ([η] 60°C) of the sheet-like or veil-like acrylic rubber molded article 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 0.7 to 0.96, particularly preferably 0.8 to 0. 95, most preferably 0.83 to 0.93, since processability, oil resistance, and shape retention are well balanced.

The characteristic values of the ash content, the total amount and ratio of magnesium and phosphorus in the ash, the gel content, the water content, and the Mooney viscosity (ML1+4,100°C) of the sheet-like or bale-like acrylic rubber molded article of the present invention are as follows: It is similar to each characteristic value of rubber.

The thickness of the sheet-like acrylic rubber molded article of the present invention is appropriately selected depending on the purpose of use, but is usually 1 mm to 45 mm, preferably 2 to 40 mm, more preferably 3 to 25 mm, particularly preferably 3 to 20 mm. range. In particular, when producing an inexpensive acrylic rubber sheet with markedly improved productivity, the thickness is usually in the range of 1 to 15 mm, preferably 2 to 10 mm, and more preferably 3 to 8 mm.

The width of the sheet-like acrylic rubber molded article of the present invention is appropriately selected depending on the purpose of use, but is usually in the range of 300 to 1,200 mm, preferably 400 to 1,000 mm, and more preferably 500 to 800 mm. In some cases, it is particularly suitable for its ease of handling. The length of the sheet-like acrylic rubber molded article of the present invention is not particularly limited, but is usually in the range of 300 to 1,200 mm, preferably 400 to 1,000 mm, and more preferably 500 to 800 mm. It is particularly suitable for its ease of handling.

The size of the veil-shaped acrylic rubber molded article of the present invention is not particularly limited, but the width is usually in the range of 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm, and the length is in the range of 250 to 450 mm. The height is usually in the range of 300 to 1,200 mm, preferably 400 to 1,000 mm, more preferably 500 to 800 mm, and the height is usually in the range of more than 50 mm and less than 500 mm, preferably 100 to 300 mm, more preferably 150 to 250 mm. be.

(Method for producing sheet-like acrylic rubber molded body)
The method for manufacturing the sheet-like acrylic rubber molded article is not particularly limited, but for example, a screw comprising a dehydration barrel having the dehydration slit, a drying barrel for drying under reduced pressure, and a die at the tip. When manufacturing acrylic rubber using a die extruder, it can be easily manufactured by making the die shape approximately rectangular and extruding it continuously.

The acrylic rubber extruded from the die of a screw-type extruder is preferably made into a roughly rectangular die shape and extruded into a sheet, as this produces dry rubber with less air entrapment, low specific gravity, and excellent storage stability. be.

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

The sheet-like acrylic rubber molded product extruded from a screw-type extruder can have a high specific gravity without entraining air at this time, and the storage stability of the obtained sheet-like acrylic rubber molded product is highly improved, which is preferable. After the sheet-like acrylic rubber molded body extruded from the screw extruder is cooled, it is cut into predetermined dimensions as necessary to obtain a sheet-like acrylic rubber molded body.

The thickness of the sheet-like acrylic rubber molded product extruded from a screw type extruder is not particularly limited, but is usually 1 to 40 mm, preferably 2 to 35 mm, more preferably 3 to 30 mm, and most preferably 5 to 25 mm. When it is within this range, it is suitable for excellent workability and productivity. In particular, since the thermal conductivity of sheet-shaped acrylic rubber molded bodies is as low as 0.15 to 0.35 W/mK, the thickness of sheet-shaped acrylic rubber molded bodies is usually The range is from 1 to 30 mm, preferably from 2 to 25 mm, more preferably from 3 to 15 mm, particularly preferably from 4 to 12 mm.

The width of the sheet-like acrylic rubber molded product extruded from a screw extruder is appropriately selected depending on the purpose of use, but the width is usually 300 to 1,200 mm, preferably 400 to 1,000 mm, and more preferably 500 to 1,000 mm. The range is 800mm.

The temperature of the sheet-like acrylic rubber molded product extruded from a screw extruder is not particularly limited, but is usually 100°C or higher, preferably 100 to 200°C, more preferably 110 to 180°C, particularly preferably 120°C. ~160°C.

The water content of the sheet-like acrylic rubber molded product extruded from the screw extruder is less than 1% by weight, preferably 0.8% by weight or less, more preferably 0.6% by weight or less.

The complex viscosity at 100°C ([η] 100°C) of the sheet-like acrylic rubber molded product extruded from a screw extruder is not particularly limited, but is usually 1,500 to 6,000 Pa·s, preferably is in the range of 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, the extrudability as a sheet and the sheet The shape is highly balanced and suitable. By setting the value of the complex viscosity at 100°C ([η]100°C) above the lower limit, better extrudability can be obtained, and by setting it below the upper limit, the shape of the sheet-like acrylic rubber molded product can be improved. It can prevent collapse and breakage.

There are no particular limitations on the method of cooling the sheet-like acrylic rubber molded product, and it may be left at room temperature, but since the thermal conductivity of the sheet-like acrylic rubber molded product is very low at 0.1 to 0.4, Forced cooling methods such as an air-cooling method under ventilation or cooling, a water-spraying method, and an immersion method in which the product is immersed in water are preferable in order to increase productivity, and particularly preferred are air-cooling methods under ventilation or cooling.

In the air cooling method for a sheet-like acrylic rubber molded product, for example, the sheet-like acrylic rubber molded product is extruded from a screw extruder onto a conveyor such as a belt conveyor, and the sheet-like acrylic rubber molded product can be transported and cooled while blowing cold air. The temperature of the cold air is not particularly limited, but is usually in the range of 0 to 30°C, preferably 5 to 25°C, more preferably 10 to 20°C. The length to be cooled is not particularly limited, but is usually in the range of 5 to 500 m, preferably 10 to 200 m, and more preferably 20 to 100 m. The cooling rate of the sheet-like acrylic rubber molded product is not particularly limited, but it is usually 50°C/hr or more, more preferably 100°C/hr or more, more preferably 150°C/hr or more before cutting. This is particularly suitable because it is easy.

There are no particular limitations on the temperature when cutting the sheet-like acrylic rubber molded product, but cutting performance and productivity are improved when the temperature is usually 60°C or lower, preferably 55°C or lower, and more preferably 50°C or lower. It is well balanced and suitable.

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

Furthermore, the ratio of the complex viscosity coefficient at 100°C ([η] 100°C) and the complex viscosity coefficient at 60°C ([η] 60°C) of the sheet-like acrylic rubber molded article ([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 Preferably, a range of 0.83 to 0.93 is preferable because air entrainment is small and cutting and productivity are highly balanced.

The cutting length of the sheet-like acrylic rubber molded product is not particularly limited and may be appropriately selected depending on the intended use of the rubber sheet, but is usually 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm. is within the range of

The thus obtained sheet-like acrylic rubber molded article of the present invention has superior operability and storage stability compared to crumb-like acrylic rubber, and can be used as it is or by laminating a plurality of sheets to form a bale.

(Method for producing veil-shaped acrylic rubber molded body)
The method for producing the bale-shaped acrylic rubber molded product of the present invention is not particularly limited, but examples include a method of laminating a plurality of the above-mentioned sheet-like acrylic rubber molded products, a method of baling crumb-shaped acrylic rubber with a baler. However, the method of laminating a plurality of sheet-shaped acrylic rubber molded bodies is preferred because it can highly improve the storage stability of the veil-shaped acrylic rubber molded bodies produced. Lamination of a plurality of sheet-like acrylic rubber molded bodies can be carried out by cutting a sheet-like acrylic rubber molded body extruded from a screw extruder after cooling, and laminating a plurality of sheets to integrate them.

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

The bale-shaped acrylic rubber molded product obtained in this way has superior operability and storage stability compared to crumb-shaped acrylic rubber, and can be used as is or by cutting the required amount into a kneading machine such as a Banbury or roll. It can be used by putting it in.

<Rubber composition>
The rubber composition of the present invention is suitable because it contains a rubber component containing the acrylic rubber of the present invention, a filler, and a crosslinking agent, so that heat resistance and water resistance are highly balanced.

As the main rubber component, the acrylic rubber of the present invention may be used alone, or, if necessary, the acrylic rubber of the present invention and other rubber components may be used in combination. The shape of the acrylic rubber of the present invention to be used may be appropriately selected depending on the purpose of use or the type of mixer used, and a sheet-like or veil-like acrylic rubber molded article can be used. The content of the acrylic rubber of the present invention in the rubber component may be selected depending on the purpose of use, and is, for example, usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably is 70% by weight or more.

Other rubber components to be combined with the acrylic rubber of the present invention are not particularly limited, and examples include natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicone rubber, fluororubber, and olefin rubber. Examples include elastomers, styrene-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, and polysiloxane-based elastomers.

These other rubber components can be used alone or in combination of two or more. The shape of these other rubber components may be any shape such as a veil shape, a sheet shape, or a powder shape. The content of other rubber components in the entire rubber component is appropriately selected within a range that does not impair the effects of the present invention, for example, usually 90% by weight or less, preferably 70% by weight or less, more preferably 50% by weight or less, especially Preferably it is 30% by weight or less.

The filler contained in the rubber composition is not particularly limited, but examples include reinforcing fillers and non-reinforcing fillers, with reinforcing fillers being preferred.

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

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

The crosslinking agent contained in the rubber composition is not particularly limited, but includes, for example, polyvalent amine compounds such as diamine compounds, and carbonates thereof; sulfur compounds; sulfur donors; triazinethiol compounds; polyvalent epoxy compounds; Conventionally known crosslinking agents such as acid ammonium salts; organic peroxides; polycarboxylic acids; quaternary onium salts; imidazole compounds; isocyanuric acid compounds; organic peroxides; triazine compounds; and the like can be used. Among these, polyvalent amine compounds and triazine compounds are preferred, and polyvalent amine compounds are particularly preferred.

Examples of the polyvalent amine compound include aliphatic polyvalent amine compounds such as hexamethylene diamine, hexamethylene diamine carbamate, N,N'-dicinnamylidene-1,6-hexane diamine; 4,4'-methylene dianiline, p -Phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(m-phenylene diisopropylidene) dianiline, 4,4'-(p-phenylene di isopropylidene) dianiline, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminobenzanilide, 4,4'-bis(4-aminophenoxy)biphenyl, m-xyly Aromatic polyvalent amine compounds such as diamine, p-xylylenediamine, and 1,3,5-benzenetriamine; and the like. Among these, hexamethylene diamine carbamate, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, and the like are preferred. These polyvalent amine compounds are particularly preferably used in combination with carboxyl group-containing acrylic rubber.

Examples of triazine compounds include 6-trimercapto-s-triazine, 2-anilino-4,6-dithiol-s-triazine, 1-dibutylamino-3,5-dimercaptotriazine, 2-dibutylamino-4, 6-dithiol-s-triazine, 1-phenylamino-3,5-dimercaptotriazine, 2,4,6-trimercapto-1,3,5-triazine, 1-hexylamino-3,5-dimercaptotriazine Examples include. These triazine compounds are particularly preferably used in combination with acrylic rubber containing a halogen group.

These crosslinking agents can be used alone or in combination of two or more, and the amount blended is usually 0.001 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the rubber component. parts, more preferably 0.1 to 5 parts by weight. By setting the amount of the crosslinking agent within this range, it is possible to obtain sufficient rubber elasticity and to obtain excellent mechanical strength as a crosslinked rubber product.

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

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

The rubber composition of the present invention includes a rubber component containing the acrylic rubber of the present invention, a filler, and a crosslinking agent as essential components, and optionally an anti-aging agent, and further contains an anti-aging agent as required. Other commonly used additives, such as crosslinking aids, crosslinking accelerators, crosslinking retarders, silane coupling agents, plasticizers, processing aids, lubricants, pigments, colorants, antistatic agents, blowing agents, etc. can be mixed arbitrarily. These other compounding agents can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the effects of the present invention.

Examples of the method for producing the rubber composition include a method of mixing a rubber component including the acrylic rubber of the present invention, a filler, a crosslinking agent, and an anti-aging agent and other compounding agents that can be contained as necessary. Any means used in the conventional rubber processing field, such as open rolls, Banbury mixers, various kneaders, etc., can be used. The mixing procedure for each component can be carried out according to the usual procedure used in the field of rubber processing. For example, components that are difficult to react or decompose with heat are thoroughly mixed, and then components that are easy to react or decompose with heat are mixed. It is preferable to mix a certain crosslinking agent or the like in a short period of time at a temperature that does not cause reaction or decomposition.

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

The rubber crosslinked product is produced by molding the rubber composition into a desired shape using a molding machine such as an extruder, injection molding machine, compressor, or roll, and then heating to cause a crosslinking reaction. It can be manufactured by fixing the shape as a crosslinked product. In this case, the crosslinking may be performed after pre-forming or at the same time as the molding. The molding temperature is usually 10 to 200°C, preferably 25 to 150°C. The crosslinking temperature is usually 100 to 250°C, preferably 130 to 220°C, more preferably 150 to 200°C, and the crosslinking time is usually 0.1 minute to 10 hours, preferably 1 minute to 5 hours. As the heating method, methods used for crosslinking rubber such as press heating, steam heating, oven heating, and hot air heating may be selected as appropriate.

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

A rubber crosslinked product using the acrylic rubber of the present invention has excellent heat resistance and processability while maintaining basic properties as a rubber such as tensile strength, elongation, and hardness.

Rubber crosslinked products using the acrylic rubber of the present invention take advantage of the above characteristics, and are used, for example, in O-rings, packings, diaphragms, oil seals, shaft seals, bearing seals, mechanical seals, well head seals, and electrical/electronic equipment. Sealing materials such as seals and seals for air compression equipment; Rocker cover gaskets installed at the connection between the cylinder block and cylinder head, oil pan gaskets installed at the connection between the oil pan and the cylinder head or transmission case, and positive electrodes. , various gaskets such as fuel cell separator gaskets installed between a pair of housings that sandwich a unit cell equipped with an electrolyte plate and a negative electrode, and hard disk drive top cover gaskets; cushioning materials, vibration-proofing materials; wire covering materials; industrial Suitable for use as belts; tubes and hoses; sheets; etc.

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

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

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

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

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

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

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

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

The drive control unit of the coagulation device 3 is configured to control the rotational drive of the motor 32 of the stirring device 34, and to set the number of rotations and the rotation speed of the stirring blades 33 of the stirring device 34 to predetermined values. The stirring blade 33 is rotated by the drive control unit so that the stirring speed of the coagulating liquid is, for example, usually 100 rpm or more, preferably 200 to 1,000 rpm, more preferably 300 to 900 rpm, particularly preferably 400 to 800 rpm. is controlled. The peripheral speed of the coagulating liquid is usually 0.5 m/s or more, preferably 1 m/s or more, more preferably 1.5 m/s or more, particularly preferably 2 m/s or more, and most preferably 2.5 m/s or more. The rotation of the stirring blades 33 is controlled by the drive control unit so that Further, the drive control unit stirs the coagulating liquid so that the upper limit of the peripheral speed of the coagulating liquid is usually 50 m/s or less, preferably 30 m/s or less, more preferably 25 m/s or less, and most preferably 20 m/s or less. Rotation of the blade 33 is controlled.

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

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

The hydrous crumbs washed by the washing device 4 are supplied to a screw type extruder 5 (see FIG. 2) which performs a dehydration process and a drying process. At this time, it is preferable that the washed water-containing crumb is supplied to the screw extruder 5 through a drainer 43 capable of separating free water. As the drainer 43, for example, a wire mesh, a screen, an electric sieve, etc. can be used.

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

The screw extruder 5 is configured to perform the processes related to the dehydration process and drying process described above. Although a screw type extruder 5 is shown here as a preferred example, a centrifugal separator, a squeezer, etc. may be used as a dehydrator that performs processing related to the dehydration process, and a dryer that performs processing related to the drying process may also be used. A hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, etc. may be used as the dryer.

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

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

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

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

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

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

The drying barrel section 54 also includes eight drying barrels, namely, a first drying barrel 54a, a second drying barrel 54b, a third drying barrel 54c, a fourth drying barrel 54d, and a fifth drying barrel 54e. , a sixth drying barrel 54f, a seventh drying barrel 54g, and an eighth drying barrel 54h.

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

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

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

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

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

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

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

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

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

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

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

In the dewatering barrel section 53, the water content of the adhesive acrylic rubber can be efficiently reduced by combining waste water and exhaust steam, which is preferable. In the dehydration barrel section 53, which dehydration barrel among the first to third dehydration barrels 53a to 53c is used to perform drainage or exhaust steam may be set as appropriate depending on the purpose of use, but it is usually manufactured. When reducing the amount of ash in the acrylic rubber, it is recommended to increase the number of dewatering barrels for draining water. In that case, for example, as shown in FIG. 2, drainage is performed in the first and second dehydration barrels 53a and 53b on the upstream side, and exhaust steam is performed in the third dehydration barrel 53c on the downstream side. Further, for example, when the dehydration barrel section 53 has four dehydration barrels, it is conceivable that, for example, three dehydration barrels on the upstream side perform drainage, and one dehydration barrel on the downstream side performs exhaust steam. On the other hand, when reducing the water content, it is preferable to increase the number of dehydration barrels for exhausting steam.

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

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

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

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

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

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

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

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

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

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

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

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

The rotational speed (N) of the pair of screws in the barrel unit 51 may be appropriately selected depending on various conditions, and is usually 10 to 1,000 rpm, which efficiently reduces the water content and gel amount of the acrylic rubber. In terms of speed, the speed is preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

Furthermore, the extrusion rate (Q) of the acrylic rubber is not particularly limited, but is usually 100 to 1,500 kg/hr, preferably 300 to 1,200 kg/hr, and more preferably 400 to 1,000 kg/hr. Yes, most preferably 500 to 800 kg/hr.

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

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

Hereinafter, as an example of the cooling device 6, a conveying cooling device 60 that cools a sheet-shaped acrylic rubber molded body 10 will be described with reference to FIG. 3.

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

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

The conveyor type cooling device 60 includes a conveyor 61 that conveys the sheet-like acrylic rubber molded body 10 discharged from the die 59 of the screw extruder 5 in the direction of arrow A in FIG. 10, and a cooling means 65 for blowing cold air onto the air conditioner 10.

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

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

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

According to the conveying type cooling device 60 shown in FIG. By blowing cooling air from the cooling means 65, the sheet-like acrylic rubber molded body 10 is cooled.

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

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

Further, the sheet-like acrylic rubber molded body 10 produced by the screw extruder 5 may be laminated to produce a veil-shaped acrylic rubber molded body. For example, a cutting mechanism for cutting the sheet-like acrylic rubber molded body 10 may be provided in the baling device 7 disposed downstream of the transport type cooling device 60 shown in FIG. Specifically, the cutting mechanism of the baling device 7 continuously cuts the cooled sheet-like acrylic rubber molded body 10 at predetermined intervals to produce cut sheet-like acrylic rubber molded bodies of a predetermined size. It is configured to be processed into 16 pieces. By stacking a plurality of cut sheet-like acrylic rubber molded bodies 16 cut to a predetermined size by a cutting mechanism, a veil-shaped acrylic rubber molded body in which cut sheet-shaped acrylic rubber molded bodies 16 are laminated can be manufactured. .

When producing a veil-shaped acrylic rubber molded body in which cut sheet-shaped acrylic rubber molded bodies 16 are laminated, it is preferable to laminate cut sheet-shaped acrylic rubber molded bodies 16 at a temperature of 40° C. or higher, for example. By laminating the cut sheet-like acrylic rubber molded bodies 16 at temperatures of 40° C. or higher, good air release can be achieved through further cooling and compression by their own weight.

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

[Monomer composition]
Regarding the monomer composition in acrylic rubber, the monomer composition of each monomer unit in acrylic rubber was confirmed by H-NMR, and it was confirmed that the activity of the reactive group remained in the acrylic rubber and its various reactions. The content of functional groups was confirmed by the following method. Moreover, the content ratio of each monomer unit in the acrylic rubber was calculated from the amount used in the polymerization reaction of each monomer and the polymerization conversion rate. Specifically, the polymerization reaction was an emulsion polymerization reaction, and the polymerization conversion rate was approximately 100%, with no unreacted monomers observed, so the content percentage of each monomer unit in the rubber was The amount used was the same as that of each monomer.

[Reactive group content]
The amount of carboxyl groups, which are reactive groups in acrylic rubber, was calculated by dissolving a rubber sample (acrylic rubber or acrylic rubber molded body) in acetone and performing potentiometric titration with a potassium hydroxide solution.

[Ash content]
The ash content (%) of the rubber sample was measured according to JIS K6228 A method.

[specific gravity]
The specific gravity of the rubber sample was measured according to method A of JIS K6268 Crosslinked Rubber Density Measurement.

[Gel amount]
The gel amount (%) of a rubber sample is the amount of insoluble matter in methyl ethyl ketone, and was determined by the following method.
Approximately 0.2 g of the rubber sample was weighed (Xg), immersed in 100 ml of methyl ethyl ketone, left to stand at room temperature for 24 hours, and the insoluble matter in methyl ethyl ketone was filtered off using an 80-mesh wire gauze. The dry solid content (Yg) obtained by evaporating and solidifying the filtrate in which only the components were dissolved was weighed and calculated using the following formula.
Gel amount (%) = 100 x (X-Y)/X

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

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

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

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

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

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

[Water resistance evaluation]
The water resistance of the rubber sample was determined by conducting an immersion test in accordance with JIS K6258 by immersing the crosslinked rubber sample in distilled water at a temperature of 85°C for 100 hours, and calculating the volume change rate before and after immersion according to the following formula. Evaluation was made using an index with Comparative Example 1 being 100 (the smaller 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

[Storage stability evaluation]
The storage stability of the rubber sample was determined 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 the rubber mixture in a rubber vulcanization tester (moving die rheometer MDR; A crosslinking test was conducted at 180°C for 10 minutes using a 100% polyester resin (manufactured by Alpha Technology), and the rate of change in crosslinking density, which is the difference between the maximum torque (MH) and the minimum torque (ML) (MH-ML), was calculated and compared. Evaluation was made using an index setting Example 1 as 100 (the smaller the index, the better the storage stability).

[Heat resistance evaluation]
To evaluate the heat resistance of the rubber sample, a heating test was performed in which the crosslinked rubber sample was left standing at 175°C for 250 hours, and the tensile strength of the crosslinked rubber product before and after the test was measured according to JIS K6251, and the hardness was measured according to JIS K6253. , Changes in elongation at break and changes in hardness were evaluated using the following criteria.
The change in elongation at break was evaluated as "◎" if the change rate in elongation at break was 20% or less, and as "x" if the change rate in elongation at break exceeded 20%. The change in hardness was evaluated as "◎" if the hardness change rate was 20 points or less, and as "x" if the hardness change rate exceeded 20 points.

[Example 1]
In a mixing container equipped with a homomixer, 46 parts of pure water, 63.25 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of methoxyethyl acrylate, 11 parts of butyl methacrylate, and fumaric acid as monomer components. 1.75 parts of monoethyl and 1.8 parts of octyloxydioxyethylene phosphate sodium salt as an emulsifier were charged and stirred to obtain a monomer emulsion.

170 parts of pure water and 3 parts of the monomer emulsion obtained above were charged into a polymerization reaction tank equipped with a thermometer and a stirring device, and the mixture was cooled to 12° C. under a nitrogen stream. Next, the remainder of the monomer emulsion, 0.00033 parts of ferrous sulfate, 0.264 parts of sodium ascorbate, and 0.22 parts of potassium persulfate were continuously added dropwise into the polymerization reaction tank over 3 hours. . After that, the reaction was continued while maintaining the temperature inside the polymerization reaction tank at 23°C, and after confirming that the polymerization conversion rate had reached approximately 100%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction. The process was stopped to obtain an emulsion polymerization solution.

Next, in a coagulation tank equipped with a thermometer and a stirring device, a 2% aqueous magnesium sulfate solution (coagulated) was vigorously stirred at a stirring blade rotation speed of 600 revolutions (peripheral speed 3.1 m/s) and heated to 80°C. The emulsion polymerization solution obtained above was heated to 80°C and continuously added to 350 parts of a coagulation solution using magnesium sulfate as a coagulation agent to coagulate the polymer. A coagulated slurry containing water was obtained. While the crumbs were filtered from the obtained slurry, moisture was discharged from the coagulated layer to obtain water-containing crumbs.

Add 194 parts of warm water (70°C) into the coagulation tank in which the filtered water-containing crumb remains, stir for 15 minutes to wash the water-containing crumb, drain the moisture, and add 194 parts of warm water (70°C) again. was added and stirred for 15 minutes to wash the water-containing crumb (total number of washings was 2 times). The washed water-containing crumb (crumb temperature 65° C.) was supplied to a screw extruder, where it was dehydrated, dried, and molded to extrude a sheet-like dry rubber (sheet-like acrylic rubber molded body) having a width of 300 mm and a thickness of 10 mm. Next, the sheet-like dry rubber was cooled at a cooling temperature of 200° C./hr using a conveying cooling device directly connected to the screw extruder.

The screw type extruder used in Example 1 has one supply barrel, three dehydration barrels (first to third dehydration barrels), and five drying barrels (first to fifth drying barrels). It is configured. The first dewatering barrel is adapted to provide drainage, and the second and third dewatering barrels provide exhaust steam. The operating conditions of the screw extruder were as follows.

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

The sheet-like dry rubber extruded from the screw extruder was cooled to 50° C. and then cut with a cutter to obtain acrylic rubber (A) (sheet-like acrylic rubber molded product). Measure the reactive group content, ash content, specific gravity, gel amount, glass transition temperature (Tg), pH, water content, weight average molecular weight, and Mooney viscosity (ML1+4,100°C) of the obtained acrylic rubber (A). The results are shown in Table 2.

Next, before the temperature of the acrylic rubber (A) falls below 40°C, the cut acrylic rubber (A) is laminated to 20 parts (20 kg) to form a veil-shaped acrylic rubber molded body (A). ) was obtained. The reactive group content, gel amount, specific gravity, ash content, glass transition temperature (Tg), pH, water content, weight average molecular weight, and Mooney viscosity (ML1+4,100) of the obtained veil-shaped acrylic rubber molded product (A) ℃) was measured. Each characteristic value of the veil-like acrylic rubber molded article (A) was similar to the characteristic value of the above-mentioned acrylic rubber (A) (sheet-like acrylic rubber molded article) shown in Table 2.

Next, 100 parts of acrylic rubber (A) (bale-shaped acrylic rubber molded body) and Compound A of "Formulation 1" listed in Table 1 were placed in a Banbury mixer and mixed at 50 ° C. for 5 minutes (first stage mixing). . The BIT at this time was measured to evaluate the processability of the acrylic rubber (A), and the results are shown in Table 2.

Furthermore, each of the mixtures obtained in the first stage mixing was transferred to a roll at 50°C, and compounding agent B of "Formulation 1" was blended and mixed (second stage mixing) to obtain a rubber mixture. A crosslinking test was conducted on the rubber mixture using acrylic rubber (A) before and after the storage stability test, and the change in crosslinking density (MH-ML) was measured. The results are shown in Table 2.

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

[Example 2]
Except that the monomer components were changed to 4.5 parts of ethyl acrylate, 53.5 parts of n-butyl acrylate, 29.5 parts of methoxyethyl acrylate, 11 parts of hexyl methacrylate, and 1.5 parts of monoethyl fumarate. Acrylic rubber (B) was obtained in the same manner as in Example 1, and its properties (the compounding agent was changed to "Blend 2") were evaluated. The results are shown in Table 2.

[Example 3]
The same procedure as in Example 2 was carried out except that the monomer components were changed to 48.6 parts of ethyl acrylate, 39 parts of n-butyl acrylate, 11 parts of butyl methacrylate, and 1.4 parts of monoethyl fumarate, and acrylic rubber ( C) was obtained and each characteristic was evaluated. The results are shown in Table 2.

[Example 4]
The same procedure as in Example 2 was carried out except that the monomer components were changed to 42.3 parts of ethyl acrylate, 45.3 parts of n-butyl acrylate, 11 parts of butyl methacrylate, and 1.4 parts of monoethyl fumarate. Acrylic rubber (D) was obtained and its properties were evaluated. The results are shown in Table 2.

[Example 5]
The procedure was carried out in the same manner as in Example 4, except that the water content after dehydration of the water-containing crumb in a screw extruder (the water content of the water-containing crumb after drainage performed before pre-drying with exhaust steam) was up to 30%. , acrylic rubber (E) was obtained and its properties were evaluated. The results are shown in Table 2.

[Comparative example 1]
200 parts of pure water, 42.3 parts of ethyl acrylate, 45.3 parts of n-butyl acrylate, and 11 parts of butyl methacrylate as monomer components were placed in a polymerization reaction tank equipped with a thermometer and a stirring device under a nitrogen stream. and 1.4 parts of monoethyl fumarate, 2.5 parts of octyloxydioxyethylene phosphate and 0.5 parts of polyoxyethylene dodecyl ether as emulsifiers, 0.1 part of potassium persulfate, and 0.0 parts of sodium ascorbate. Then, 0.1 part of potassium persulfate and 0.1 part of sodium ascorbate were added to start the reaction. The reaction was continued at room temperature, and after confirming that the polymerization conversion rate had reached approximately 100%, hydroquinone as a polymerization terminator was added to stop the polymerization reaction, and an emulsion polymerization liquid was obtained.

Next, a 0.4% aqueous sodium sulfate solution (a coagulating liquid using sodium sulfate as a coagulant) was added to the emulsion polymerization liquid that was being stirred at a stirring blade rotation speed of 100 revolutions (peripheral speed 0.5 m/s) of a stirring device. The polymer was coagulated to obtain a coagulated slurry containing acrylic rubber crumbs and water. While the crumbs were filtered from the obtained slurry, moisture was discharged from the coagulated layer to obtain water-containing crumbs.

194 parts of 25° C. water was added to the coagulation tank in which the filtered water-containing crumbs remained, and the water-containing crumbs were washed by stirring for 15 minutes, and then the water was drained and the water-containing crumbs were washed. The washed water-containing crumb was dried in a hot air dryer to obtain a crumb-like acrylic rubber (F) having a water content of 0.4% by weight. Regarding this acrylic rubber (F), the reactive group content, gel amount, specific gravity, ash content, glass transition temperature (Tg), pH, water content, weight average molecular weight, and Mooney viscosity (ML1+4,100°C) were measured. The results are shown in Table 2.

Next, 100 parts of acrylic rubber (F) and Compound A of "Composition 2" listed in Table 1 were placed in a Banbury mixer and mixed at 50° C. for 5 minutes (first stage mixing). The BIT at this time was measured to evaluate the processability of the acrylic rubber (F), and the results are shown in Table 2. Furthermore, each of the mixtures obtained in the first stage mixing was transferred to a roll at 50° C., and compounding agent B of "Blend 2" was blended and mixed (second stage mixing) to obtain a rubber mixture. A crosslinking test was conducted on the rubber mixture using acrylic rubber (F) before and after the storage stability test, and the change in crosslinking density (MH-ML) was measured. The results are shown in Table 2.

The obtained rubber mixture was put into a mold with 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 while applying a press pressure of 10 MPa to obtain a primary crosslinked product. was further heated in a gear type oven at 180° C. for 2 hours to cause secondary crosslinking, thereby obtaining a sheet-like crosslinked rubber product. Then, a test piece of 3 cm x 2 cm x 0.2 cm was cut out from the obtained sheet-like crosslinked rubber product and evaluated for water resistance and heat resistance, and the results are shown in Table 2.

From Table 2, 10 to 98.9% by weight of bonding units derived from acrylic esters (A), 1 to 50% by weight of bonding units derived from methacrylic esters, bonding units derived from reactive group-containing monomers ( C) 0.1 to 10% by weight and bonding units derived from other monomers (D) 0 to 30% by weight, the gel amount of methyl ethyl ketone insoluble matter is 30% by weight or less, and the weight average molecular weight (Mw) The acrylic rubbers (A) to (E) of the present invention, in which the (Comparison between Examples 1 to 5 and Comparative Example 1).

From Table 2, the processability (BIT) of acrylic rubber in the Banbury mixer is correlated with the gel amount of methyl ethyl ketone insoluble components in the acrylic rubber, and in order to reduce the gel amount, it is necessary to It can be seen that it is important to melt and rotate the acrylic rubber in a substantially water-free state (water content less than 1% by weight). On the other hand, leaving acrylic rubber in a screw-type extruder for a long time causes molecular breakage and burning, which deteriorates the acrylic rubber's normal physical properties including its strength, heat resistance, and storage stability, which is undesirable. As can be seen from 2, the challenge is how to dehydrate the dehydrating barrel section efficiently in order to quickly make the drying barrel section substantially moisture-free. It is cleared by adjusting the degree. In addition, in order to prevent deterioration of the acrylic rubber that is melted and rotated in a drying barrel section in a substantially water-free state and to reduce the water content and gel amount of the acrylic rubber, the extrusion amount Q of the screw type extruder and the rotation It was important to have a specific ratio (Q/N) to the number N (1 to 20, preferably 2 to 10, more preferably 3 to 8, particularly preferably 4 to 6).

Table 2 also shows that the acrylic rubbers (A) to (E) of the present invention have significantly superior water resistance when dehydrated (squeezing out water from water-containing crumbs) in the drying process (Example 1 ~5 and Comparative Example 1).

Table 2 further shows that the acrylic rubbers (A) to (E) (acrylic rubber molded products) of the present invention, which have a large specific gravity and do not contain air, have highly improved storage stability without impairing heat resistance. It can be seen that (comparison between Examples 1 to 5 and Comparative Example 1).

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

Claims (13)

10 to 98.9% by weight of bonding units derived from acrylic esters (A), 1 to 50% by weight of bonding units derived from methacrylic esters, and at least one selected from the group consisting of carboxyl groups, epoxy groups, and halogen groups. The gel consists of 0.1 to 10% by weight of bonding units (C) derived from a monomer having a specific functional group and 0 to 30% by weight of bonding units (D) derived from other monomers, and contains a portion insoluble in methyl ethyl ketone. Acrylic rubber in an amount of 5% by weight or less and a weight average molecular weight (Mw) in the range of 100,000 to 5,000,000. The acrylic rubber according to claim 1, having an ash content of 1% by weight or less. The acrylic rubber according to claim 1 or 2, which is obtained by emulsion polymerization using a phosphoric acid ester salt or a sulfuric acid ester salt as an emulsifier. The acrylic rubber according to any one of claims 1 to 3, which is obtained by coagulating the emulsion-polymerized polymer solution using an alkali metal salt or a Group 2 metal salt of the periodic table as a coagulant and drying it. The acrylic rubber according to any one of claims 1 to 4, which is dried using a screw extruder after solidification. The acrylic rubber according to claim 5 , wherein the drying using the screw extruder is performed under reduced pressure. The acrylic rubber according to claim 5 or 6, which is cooled at a cooling rate of 50° C./hr or more after drying using the screw extruder. Acrylic acid ester (a), methacrylic acid ester (b), a monomer (c) having at least one functional group selected from the group consisting of carboxyl group, epoxy group and halogen group , and optionally copolymerized. An emulsion polymerization step in which a monomer component consisting of possible other monomers (d) is emulsified with water and an emulsifier, and then emulsion polymerized in the presence of a polymerization catalyst to obtain an emulsion polymerization liquid;
A coagulation step of bringing the obtained emulsion polymerization liquid into contact with a coagulation liquid to produce water-containing crumb;
a cleaning step of cleaning the generated water-containing crumb;
a drying step of drying the washed water-containing crumb using a screw extruder until the water content is less than 1% by weight;
A method for producing acrylic rubber, including: The method for producing acrylic rubber according to claim 8 , wherein the ratio (Q/N) of the extrusion amount (Q) to the rotation speed (N) of the screw extruder is in the range of 2 to 10. A sheet-like or veil-like acrylic rubber molded article made of the acrylic rubber according to any one of claims 1 to 7 . The acrylic rubber molded article according to claim 10 , having a specific gravity of 0.8 or more. A rubber composition comprising a rubber component containing the acrylic rubber according to any one of claims 1 to 7 , a filler, and a crosslinking agent. A crosslinked rubber product obtained by crosslinking the rubber composition according to claim 12 .

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