JP2001131223A - Method for production of acrylic rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an acrylic rubber excellent in the balance among resistances to cold, oil, and heat. SOLUTION: In this method, a latex of an acrylic rubber comprising 0.1 wt.% or higher but lower than 3 wt.% ethylene monomer units, 0-10 wt.% cross-linking monomer units, and 99.9-87 wt.% at least one kind of alkyl acrylate units is continuously subjected to coagulation, dehydration, cleaning, and drying in a dehydrating and drying apparatus of a screw extruder type to give a dry rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of continuously solidifying, dehydrating, washing and drying a latex of an acrylic rubber having a specific composition using a screw extruder-type dehydration / drying apparatus to provide a cold-resistant material. The present invention relates to a method for continuously producing an acrylic rubber having an excellent balance between oil resistance, oil resistance and heat resistance.

[0002]

2. Description of the Related Art In recent years, as industries have become larger and faster,
The rubber parts used for these are required to maintain higher and higher durability. In particular, larger sizes and higher speeds cause the operating temperature of machinery and equipment to rise, so that rubber parts are required to have a high degree of heat resistance, and at the same time, lubricating oil temperatures are increased due to the increase in lubricating oil temperature. There is a demand for improved performance. In addition, demands for cold resistance of rubber parts have been increasing due to use in harsh environments such as cold regions due to widespread industrial activities.

On the other hand, in the engine room of automobiles, thermal conditions have become more severe due to measures against exhaust gas, high output of the engine, and the like. Instead, acrylic rubber having excellent heat resistance and oil resistance has been used.
However, the severer thermal conditions in the engine and engine room make it easier to extract the plasticizer compounded in the rubber for imparting cold resistance, which impairs the cold resistance of the rubber,
It is known that the engine oil itself creates a deteriorating environment, and this degraded engine oil further attacks the rubber hose to degrade the rubber material. Therefore, lubricating oil hose materials used in the engine room are more oil-resistant,
There is a demand for cold resistance and heat resistance, and there is also a demand for improved performance of acrylic rubber that has come to be used as a heat-resistant and oil-resistant material. In addition, rubber parts for automobiles are basically required to have a permanent compression set to maintain water resistance and sealability. In addition, as the lubricating oils become lower in viscosity due to the higher performance of automobile lubricating oils, further oil resistance is required. There is a need for improved properties and cold resistance.

Japanese Patent Publication No. Sho 59-14498 discloses an ethylene (A) -vinyl acetate (B) -acrylate (C) copolymer in which (C) is 6 to 90% by weight and (A) /
It is described that a rubber composition comprising a copolymer having a weight ratio of (B) of 1 or less and a vulcanizing agent is excellent in oil resistance, heat resistance and weather resistance. Also, JP-A-63-3123
No. 38 discloses a copolymer of ethylene having a content of ethylene component of 3 to 10% by weight and another copolymer component, wherein the other copolymer component is vinyl acetate 0 to 10% by weight, acrylic Copolymers comprising 20% to 45% by weight of ethyl acrylate and 45 to less than 45% by weight of n-butyl acrylate and compositions thereof are described. In these compositions, improvement in oil resistance is recognized to some extent, and in the latter, some improvement effect of cold resistance is also recognized.However, due to the harsh conditions of use as described above, oil resistance, cold resistance and heat resistance are improved. Further improvement was required in the balance of sex.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and further provides a method for producing an acrylic rubber having an excellent balance between cold resistance, oil resistance and heat resistance.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that ethylene monomer units, crosslinkable monomer units and specific acrylate ester monomer units By continuously performing coagulation, dehydration, washing and drying in a screw extruder of a copolymer having a specific composition ratio, the balance of cold resistance, oil resistance and heat resistance is extremely excellent. As a result, they have found that a rubber having good water resistance and good compression set required as a rubber part for automobiles has been obtained, and have completed the present invention. That is, the present invention provides a total of 9 to less than 0.1 to 3% by weight of ethylene monomer units, 0 to 10% by weight of crosslinking monomer units, and one or more alkyl acrylate monomer units.
Production of an acrylic rubber characterized by producing a dry rubber by continuously performing coagulation, dehydration, washing and drying in an extruder from 9.9 to 87% by weight of an acrylic rubber latex. Is the way.

Hereinafter, the present invention will be described in detail. The acrylic rubber of the present invention contains one or two or more ethylene monomer units of 0.1 to less than 3% by weight, preferably 0.5 to 2.5% by weight, and the above-mentioned crosslinkable monomer units of 0 to 10% by weight. The total of at least one kind of alkyl acrylate monomer units is 99.9 to 87.
Acrylic rubber consisting of% by weight. As the alkyl acrylate of the present invention, ethyl acrylate, n-butyl acrylate, methyl acrylate, n-propyl acrylate, isobutyl acrylate, n-pentyl acrylate,
Isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate,
Examples thereof include 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, and n-octadecyl acrylate, and an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms is preferable. Also,
More preferably, the alkyl acrylate of the present invention is ethyl acrylate and / or n-butyl acrylate. These alkyl acrylates can be used alone or in combination of two or more.

Examples of the crosslinking monomer used in the present invention include those having an active chlorine group such as 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, vinylbenzyl chloride, vinyl chloroacetate, and allyl chloroacetate. In addition, acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, those containing a carboxylic acid group such as maleic acid monoalkyl ester,
Glycidyl acrylate, glycidyl methacrylate,
Those containing an epoxy group such as allyl glycidyl ether and methallyl glycidyl ether are exemplified. The acrylic rubber in the present invention desirably contains these crosslinkable monomer units in an amount of 0 to 10% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.5 to 3% by weight.

The crosslinking monomer used in the acrylic rubber of the present invention includes those containing an epoxy group, those containing an active chlorine group, a carboxylic acid group, and those containing both an epoxy group and a carboxylic acid group. .

The acrylic rubber of the present invention may be obtained by copolymerizing another monomer copolymerizable with the above-mentioned monomer within a range not to impair the object of the present invention. As other copolymerizable monomers, cyanomethyl acrylate, 1-cyanoethyl acrylate, 2-cyanoethyl acrylate, 1-cyanopropyl acrylate, 2-cyanopropyl acrylate, 3-cyanopropyl acrylate,
Examples include alkyl acrylates such as 4-cyanobutyl acrylate, 6-cyanohexyl acrylate, 2-ethyl-6-cyanohexyl acrylate, and 8-cyanooctyl acrylate.

Also, 2-methoxyethyl acrylate,
2-ethoxyethyl acrylate, 2- (n-propoxy) ethyl acrylate, 2- (n-butoxy) ethyl acrylate, 3-methoxypropyl acrylate,
And alkoxyalkyl acrylates such as -ethoxypropyl acrylate, 2- (n-propoxy) propyl acrylate and 2- (n-butoxy) propyl acrylate.

Further, 1,1-dihydroperfluoroethyl (meth) acrylate, 1,1-dihydroperfluoropropyl (meth) acrylate, 1,1,5-trihydroperfluorohexyl (meth) acrylate,
1,2,2-tetrahydroperfluoropropyl (meth) acrylate, 1,1,7-trihydroperfluoroheptyl (meth) acrylate, 1,1-dihydroperfluorooctyl (meth) acrylate, 1,1-dihydroperfluorodecyl (meth) A) Fluorine-containing acrylates such as acrylate, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyl-containing acrylates such as hydroxyethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dibutyl Tertiary amino group-containing acrylates such as aminoethyl (meth) acrylate, methacrylates such as methyl methacrylate and octyl methacrylate, and alkyl vinyls such as methyl vinyl ketone Ketones, vinyl and allyl ethers such as vinyl ethyl ether and allyl methyl ether, vinyl aromatic compounds such as styrene, α-methyl styrene, chlorostyrene and vinyl toluene, vinyl nitriles such as acrylonitrile and methacrylonitrile, ethylene, propylene, chloride Examples include ethylenically unsaturated compounds such as vinyl, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl acetate, vinyl propionate, and alkyl fumarate.

The acrylic rubber latex used in the present invention is a latex obtained by ordinary emulsion polymerization, and there is no limitation on the emulsifier used for the polymerization.
Those using A as an emulsifier are particularly preferred. The type of PVA may be any of partially saponified PVA, fully saponified PVA, and modified PVA, and the amount of PVA used is 2 to 7 parts by weight, preferably 4 to 7 parts by weight based on 100 parts by weight of the polymer. Department.

As the coagulant, any compound capable of coagulating the acrylic rubber latex can be used. In particular, when PVA is used as an emulsifying system, a gelling agent for PVA is effective. Examples of the gelling agent include a boron compound and a compound containing a sulfate group.
It is also effective to use two or more of these gelling agents.

As the boron compound, there are boric acid, potassium tetraborate, ammonium hydrogen tetraborate, sodium tetraborate (borax) and the like, and any boron compound may be used, but borax is most effective. And a preferred coagulant. The compound having a sulfate group is not particularly limited as long as it has solubility in water, and examples thereof include sodium sulfate, potassium sulfate, ammonium sulfate, ferrous sulfate, copper sulfate, zinc sulfate, aluminum sulfate, and potassium hydroxide. Although alum and sulfuric acid can be used, sodium sulfate and ammonium sulfate are particularly preferred. The amount of the coagulant used is 0.2 to 15 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the polymer. If the amount of the coagulant is less than 0.2 parts by weight, the polymer is not sufficiently coagulated, the separated water becomes cloudy, and the yield of the dried polymer becomes poor. If the amount is more than 15 parts by weight, the coagulant may remain in the polymer, deteriorating the physical properties of the polymer.

The dewatering and drying apparatus used in the present invention is of a screw extruder type, as long as it can perform at least dehydration and drying in the same apparatus. Any function may be used as long as it is a screw extruder type having the same drainage function as drainage from water slits and drying by heating and exhaustion from vent holes. The casing of the dewatering / drying device may be a split type or an integral type, and the screw may be a combination of split type or an integrated type, but since the suitable function can be selected by a free combination, it is divided. Formulas are preferred. Screws are feed direction screws,
Reverse screw etc. can be freely combined and used,
Basically, self-cleaning of the mutual scraping method is preferable.

Although not limited to the apparatus and method described below, the method of the present invention and the apparatus to be used will be described using the apparatus used in the embodiment of the present invention as an example. FIG. 1 is an explanatory view showing the entire apparatus, FIG. 3 is a relation between a casing and a screw of a dehydrating / drying apparatus, and FIG. 4 is a schematic view of engagement of a scraping type (self-cleaning type) screw.

In FIG. 1, 1 is an acrylic rubber latex storage tank, 3 is a coagulation liquid storage tank, 2 and 4 are pumps, and 5 is a co-rotating twin-screw extruder type dehydration / drying apparatus.
It is obtained by connecting M divided casings. A is a raw material supply casing, B, D, and H are slit casings, C and F are press-fit casings having press-fit holes P and Q, respectively, J and L are vent casings having vent holes V1 and V2, and others are simple casings. A die for taking out dried rubber is attached to the casing M. As shown in FIGS. 3 and 4, the screws are of a self-cleaning type that scrapes each other by rotating in two axes in the same direction, and is a split type as in the case of the casings A to M. Further, as shown in FIG. 2, a reverse screw Z is combined.

The acrylic rubber latex and the coagulation liquid press-fitted by the pumps 2 and 4 are mixed and mixed in the casing A.
It is solidified and transferred in the forward direction. The coagulated material containing water and residual coagulated salts stays in the slit casings B and D for a very short time by the reverse screw Z to be dehydrated. Further, residual coagulated salts are caused to flow out of the extruder system from the slit casings B and D by warm water convected from the injection holes P and Q, and the coagulated material is washed. In the casing I to M,
Increase the temperature of the casing, and further vent holes V1, V2
By reducing the pressure, the water content of the coagulated material can be reduced, and a copolymer is obtained from the tip of the casing M.

The solid content of the acrylic rubber latex is not limited, but is preferably 20 to 50% by weight. If it is less than 20% by weight, the productivity is poor, and if it exceeds 50% by weight, coagulation becomes insufficient.

When the flow rate of the acrylic rubber latex, the coagulating liquid and the hot water for washing is 10 (volume), the flow rate of the coagulating liquid is preferably 2 to 10, more preferably 3 to 6. When the flow rate is less than 2, the coagulation is insufficient, and when it exceeds 10, the residual coagulation salts increase. The flow rate of the washing hot water is 0 to 50 as the total amount of the press-fit holes P and Q.
Is preferable, and 5-20 are more preferable. If the flow rate exceeds 50, the loss rubber from the slit casing increases.

The temperatures of the casings A to M and the reduced pressure of the vent are adjusted according to the desired water content of the copolymer. However, if the temperature of the casing exceeds 250 ° C., the deterioration of the copolymer itself proceeds. Not preferred.

The acrylic rubber of the present invention is used after being vulcanized using a vulcanizing system usually used for acrylic rubber. The vulcanizing system to be applied is a vulcanizing system containing an imidazole compound. Particularly, a vulcanization system obtained by adding trimethylthiourea to this is more preferably used.

The imidazole compounds include 1-methylimidazole, 1,2-dimethylimidazole, 1-methylimidazole,
Methyl-2-ethylimidazole, 1-benzyl-2-
Ethyl imidazole, 1-benzyl-2-ethyl-5
Methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole.
Trimellitate, 1-aminoethylimidazole, 1
-Aminoethyl-2-methylimidazole, 1-aminoethyl-2-ethylimidazole, 1-cyanoethyl-
2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4
-Methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-methylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate, 1-cyanoethyl-
2-ethyl-4-methylimidazole trimellitate,
1-cyanoethyl-2-undecyl-imidazole trimellitate, 2,4-diamino-6- [2′-methylimidazolyl- (1) ′] ethyl-s-triazine / isocyanuric acid adduct, 1-cyanoethyl-2 -Phenyl-4,5-di- (cyanoethoxymethyl) imidazole, N- (2-methylimidazolyl-1-ethyl) urea, N, N'-bis- (2-methylimidazolyl-1-)
Ethyl) urea, 1- (cyanoethylaminoethyl) -2
-Methylimidazole, N, N '-[2-methylimidazolyl- (1) -ethyl] -aziboyldiamide, N,
N '-[2-methylimidazolyl- (1) -ethyl]-
Dodecandioyl diamide, N, N '-[2-methylimidazolyl- (1) -ethyl] -eicosandioildiamide, 2,4-diamino-6- [2'-methylimidazolyl- (1)']-ethyl -S-triazine, 2,4
-Diamino-6- [2'-undecylimidazolyl-
(1) ']-ethyl-s-triazine, 1-dodecyl-
2-methyl-3-benzylimidazolium chloride,
1,3-dibenzyl-2-methylimidazolium chloride and the like.

The amount of the imidazole compound is preferably from 0.2 to 100 parts by weight of the acrylic rubber.
It is 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight. If it is less than 0.2 parts by weight, the physical properties of the vulcanized product are not sufficient. May be damaged.

The addition amount of trimethylthiourea is preferably 0.1 to 5.0 parts by weight, more preferably 0.3 to 4.0 parts by weight, based on 100 parts by weight of the acrylic rubber. If the amount is less than 0.1 part by weight, the vulcanization rate and the compression set are not sufficiently improved. If the amount exceeds 5.0 parts by weight, there is a possibility that a problem may occur in molding.

In the present invention, for the purpose of adjusting the vulcanization rate, a curing agent for an epoxy resin, such as a pyrolytic ammonium salt, an organic acid, an acid anhydride, an amine, sulfur and a sulfur compound, is further used in the present invention. The effect can be added as long as the effect is not reduced.

When the acrylic rubber of the present invention is put to practical use, it can be molded and vulcanized by adding a filler, a plasticizer, a stabilizer, a lubricant, a reinforcing material and the like according to the purpose. Carbon black used as a filler in the vulcanizate of the present invention has an average particle diameter of less than 20 to 30 nm,
Those having a P oil absorption of 115 ml / 100 g or more are preferred.
As a specific example, Tokai Carbon Co., Ltd.
Seat # 6, Seast 5H, Seast KH, Seast 3H, Seast NH, Seast N, etc., Asahi Carbon Co., Ltd. Asahi # 80 and the like. The average particle size of carbon black refers to a value represented by a length average particle size measured by an electron microscope. The DBP oil absorption is JIS K622.
It refers to a value measured according to Method A (mechanical method) of No. 1. If the average particle size or DBP oil absorption of the carbon black is out of the above range, the balance between the extrudability, the surface smoothness and the tensile strength tends to be lost. These carbon blacks can be used alone or as a mixture of two or more kinds due to required rubber properties. These carbon blacks are added in a total amount of 30 to 100 which is usually used for 100 parts by weight of the acrylic rubber.
Parts by weight are preferred.

Further, as the acrylic rubber of the present invention and a composition for kneading, molding and vulcanizing the vulcanizate and the composition using the acrylic rubber as a raw material, those usually used in the rubber industry can be used. .

The composition of the present invention using the acrylic rubber of the present invention as a raw material and the vulcanized product thereof are particularly suitably used as sealing parts such as rubber hoses, gaskets and packings. The rubber hose is specifically used for hoses used in various piping systems of automobiles, construction machines, hydraulic equipment, and the like. In particular, a rubber hose obtained from a composition using the acrylic rubber of the present invention as a raw material and a vulcanized product thereof,
In addition to extrudability and rubber properties such as tensile strength, oil resistance, cold resistance and heat resistance are excellent,
In particular, it is very suitably used as a rubber hose for automobiles whose use environment has recently become severe.

The rubber hose may be composed of a single hose obtained from the acrylic rubber of the present invention or, depending on the application of the rubber hose, a synthetic rubber other than the acrylic rubber of the present invention may be added to the layer of the acrylic rubber of the present invention. For example, fluorine rubber, fluorine-modified acrylic rubber, hydrin rubber, C
Application to a composite hose combining SM, CR, NBR, ethylene / propylene rubber, etc. as an inner layer, an intermediate layer, or an outer layer is also possible. Further, depending on the characteristics required of the rubber hose, it is also possible to provide a reinforcing thread or a wire in the middle of the hose or on the outermost layer of the rubber hose, as is generally done.

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. First, the apparatus used in the examples will be described. FIG. 1 is an explanatory view showing the entire apparatus, and FIG.
FIG. 3 is a schematic diagram of the relationship between the casing of the drying device and the screw, and FIG. 3 shows the engagement of a scraping type (self-cleaning type) screw.

In FIG. 1, reference numeral 1 denotes an acrylic rubber latex storage tank, reference numerals 2 and 4 denote pumps, reference numeral 3 denotes a coagulation liquid storage tank, and reference numeral 5 denotes a co-rotating twin-screw extruder type dehydrating / drying apparatus.
Are connected to each other. A is a raw material supply casing, B, D and H are slit casings,
F is a press-fit casing having a press-fit hole P, J and L are vent casings having vent holes V1 and V2, and the other are simple casings. A casing M is provided with a die for taking out dry rubber. As shown in FIGS. 3 and 4, the screws are of a self-cleaning type that scrapes each other by rotating in two axes in the same direction, and is a split type as in the case of the casings A to M.

Example 1 A pressure-resistant reaction vessel having an inner volume of 40 liters was charged with 11 kg of a mixture of 5.5 kg of ethyl acrylate and 5.5 kg of n-butyl acrylate, 17 kg of an aqueous solution of 4% by weight of partially saponified polyvinyl alcohol, and sodium acetate. 22 g and glycidyl methacrylate (120 g) were charged and mixed well in advance with a stirrer to prepare a uniform suspension. After replacing the air in the upper part of the tank with nitrogen, ethylene was injected into the upper part of the tank and the pressure was increased to 5%.
It was adjusted to kg / cm ² . Continue stirring, and keep the inside of the tank at 55 ° C.
Then, an aqueous solution of t-butyl hydroperoxide was separately injected from the injection port to start polymerization. During the reaction, the temperature in the tank was kept at 55 ° C., and the reaction was completed in 6 hours. Precipitation and drying were carried out using the apparatus shown in FIG. 1 and the latex after polymerization adjusted to a solid content of 35% by weight was supplied from storage 1 at a supply rate of 60 L / hr, and a mixed aqueous solution of borax and ammonium sulfate (borax 2 wt. %, Ammonium sulfate 2% by weight)
Was supplied from the storage tank 3 from the pumps 2 and 4 at 40 L / hr, respectively. With the start of the supply, the screw rotation speed of the dehydrating / drying device 5 was gradually increased to 150 rpm, and the vacuum pump directly connected to the vent holes V1 and V2 of the vent casings J and L was operated. A steady state was reached 10 minutes after the start, and a copolymer having a water content of 0.4% by weight and a colorless color at 20 kg / hr was obtained from the tip of the casing M.
The temperature of the casing was set as follows, and hot water at a temperature of 80 ° C. was supplied through the press-in hole P of the casing F and the press-in hole Q of the casing C, respectively, at 100 L / hr and 50 L / h.
r. On the other hand, as for the water discharged from the slit, 70 L / hr of the transparent separated water in the casing B, and 120 L / hr in the casing D
/ Hr, in casing H, only steam was discharged (polymer yield: 95% by weight).

Examples 2 to 5 Methyl acrylate and / or ethyl acrylate and / or acrylic acid were prepared in the same manner as in Example 1 so that the composition ratios of the copolymers shown in Table 1 were obtained. A mixed solution of n-butyl and / or 2-ethylhexyl acrylate is charged, and ethylene pressure is set to 40 kg / cm.
As No. ² , a raw rubber of a copolymer was obtained.

Comparative Examples 1-2, Comparative Examples 5-6 The same method as in Example 1 was used, except that ethylene was introduced so that an acrylic rubber having a copolymer composition ratio shown in Table 2 was obtained. To obtain a raw rubber of a copolymer.

COMPARATIVE EXAMPLE 3 The same method as in Example 1 was used except that glycidyl methacrylate (190 g) and ethylene pressure were set to 80 kg / cm ² .
A copolymer raw rubber was obtained.

Comparative Example 4 A method similar to that of Example 3 was adopted, except that the ethylene pressure was set to 50 k.
g / cm ² to obtain a raw rubber of a copolymer.

Comparative Examples 5 to 7 The same method as in Examples 1 to 3, except that the latex after polymerization was applied on a glass plate so as to have a thickness of about 3 mm.
After drying at 0 ° C. for 24 hours, a raw rubber of a copolymer was obtained.

Preparation of vulcanized products (Examples 1 to 5, Comparative Examples 1 to 5)
7) The raw rubbers obtained in the above Examples and Comparative Examples were kneaded with an 8-inch open roll according to the composition shown in Table 3, and separated into sheets having a thickness of 2.4 mm.
Press vulcanization was performed at 70 ° C. for 10 minutes. This vulcanized product was further subjected to a heat treatment at 170 ° C. for 4 hours in a gear oven and subjected to a physical property test.

Analytical Test Method After the raw rubber of the copolymer was tightly passed through a roll, it was dissolved in toluene, and a nuclear magnetic resonance spectrum was collected to quantify each component. Nuclear magnetic resonance spectra were collected by JEOL JN
Mα-500 was used.

Test Methods for Physical Properties Tensile strength and elongation were measured in accordance with JIS K6251. The hardness was measured according to JIS K6253.
The compression set is 150 according to JIS K6262.
The strain at 70 ° C. after 70 hours was measured. Oil resistance (ΔV) is J
In accordance with IS K6258, 15 for IRM-903 oil
The volume change ΔV (%) after immersion at 0 ° C. for 70 hours was determined. The cold resistance was determined according to JIS K6261 at a temperature of t100 by a low-temperature torsion test. Heat resistant AR (EB)
Measured the elongation retention AR (EB) (%) in a tensile test after exposure at 175 ° C. for 70 hours in accordance with JIS K6257. Tables 1 and 2 show the measurement results of the vulcanizates for the respective examples and comparative examples.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

The level of cold resistance is -35 at a temperature of t100.
Comparing the data of Example 1 with Comparative Example 2 and Comparative Example 3 which are the same as in ° C, Example 1 of the present invention is extremely excellent in oil resistance ΔV, and the level of cold resistance is equal to -39 ° C. Comparison between Example 3 and Comparative Example 4 also shows Example 3 of the present invention.
Has excellent oil resistance. Further, the first and third embodiments of the present invention have good heat resistance levels. On the other hand, comparing Example 1 with Comparative Example 1 in which the oil resistance level is equal to 40% in ΔV,
Example 1 of the present invention is far superior in cold resistance.
Example 1 of the present invention also has an excellent level of heat resistance.
In Example 1 and Comparative Example 7, Example 2 and Comparative Example 8, and Example 3 and Comparative Example 9 were prepared by using latexes having the same polymerization composition as in Example 1.
Reference numerals 3 to 3 denote extruders of this patent, and Comparative Examples 7 to 9 show physical properties of vulcanized products using raw rubber dried in the form of a film.
Both of the comparative examples have poor water resistance and compression set.

[0047]

As shown by the comparison between the examples and the comparative examples, the vulcanizates made of the acrylic rubber-based composition according to the production method of the present invention have excellent rubber properties such as water resistance and compression set. As well as having excellent balance of oil resistance, cold resistance and heat resistance.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the entire apparatus.

FIG. 2 is a screw combination diagram showing a reverse screw Z.

Fig. 3 Relationship between casing and screw of dewatering / drying device

FIG. 4 is a schematic diagram of the engagement of a scraping type (self-cleaning type) screw.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Acrylic rubber latex storage tank 2, 4 Pump 3 Coagulation liquid storage tank 5 Dehydration / drying device of the co-rotating twin-screw screw extruder type A to M Divided casing A Raw material supply casing B, D, H Slit casing C Press-fit Pressure casing with hole Q F Press-fit casing with press-in hole P J, L Vent casing with vent holes V1, V2 M Casing with die for removing dry rubber P, Q Press-in hole V1, V2 Vent hole Z Reverse screw screw

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J100 AA02Q AB08R AE09R AE18R AE26R AG08R AG10R AJ01R AJ02R AJ08R AJ09R AL03P AL04P AL08R AL10R BB01R BC54R CA04 CA05 EA07 GC07 GC25 GC35 GC37 JA28

Claims (3)

[Claims] 1. A total of 9 to less than 0.1 to 3% by weight of an ethylene monomer unit, 0 to 10% by weight of a crosslinking monomer unit and one or more alkyl acrylate monomer units.
Coagulation from an acrylic rubber latex consisting of 9.9 to 87% by weight in a screw extruder type dewatering / drying device,
A method for producing an acrylic rubber, comprising producing a dry rubber by continuously performing dehydration, washing and drying. 2. The method for producing an acrylic rubber according to claim 1, wherein the alkyl acrylate is an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms. 3. The method for producing an acrylic rubber according to claim 1, wherein the alkyl acrylate is ethyl acrylate and / or n-butyl acrylate.