JPWO2019003917A1 - Method for producing crosslinked acrylic rubber molded article, acrylic rubber composition and sealing material - Google Patents

Abstract

Provided is a method for producing a crosslinked acrylic rubber molded article which has improved production efficiency while maintaining rubber properties such as compression set. Moreover, the acrylic rubber composition used for the said manufacturing method is provided. Crosslinking characterized by molding and crosslinking an acrylic rubber composition containing 100 parts by mass of an acrylic rubber having a crosslinkable group, 0.1 to 30 parts by mass of a porous body, and 0.1 to 10 parts by mass of a diurethane compound. It is a method for producing an acrylic rubber molded body. Further, it is an acrylic rubber composition used in the method for producing the crosslinked acrylic rubber molded body. Further, it is a sealing material made of a cross-linked product of the acrylic rubber composition.

Description

  The present invention relates to a method for producing a crosslinked acrylic rubber molded article, an acrylic rubber composition, and a sealing material composed of a crosslinked product of the acrylic rubber composition.

  Acrylic rubber compositions are widely used for sealing parts such as O-rings, gaskets, oil seals and packings because they have excellent heat resistance, oil resistance and price balance. There is a type of acrylic rubber having a chlorine group, an epoxy group, an active chlorine group, an active chlorine group / carboxyl group, a carboxyl group or the like as a crosslinkable group. Among them, acrylic rubber having a carboxyl group as a crosslinkable group is characterized by a high crosslinking rate and excellent compression set.

  In order to produce a cross-linked molded article using an acrylic rubber, generally, a predetermined cross-linking agent, a cross-linking accelerator, etc. are added to an acrylic rubber having a cross-linkable group to form an acrylic rubber composition, which is molded and cross-linked. It can be manufactured by The order of the molding step and the crosslinking step of the acrylic rubber composition is not particularly limited. Regarding the cross-linking agent and cross-linking accelerator used for cross-linking the acrylic rubber, some specific examples are disclosed in Patent Document 1, for example.

Japanese Patent No. 5229430

  However, in the production of a crosslinked molded article of acrylic rubber, in the step of molding / crosslinking the acrylic rubber composition, decomposition products or by-products associated with the reaction at the time of cross-linking are fixed to the molding device or the mold, There is a concern that the production efficiency will be reduced, and there is room for further improvement.

  The present invention has been made in view of such a situation. That is, an object of the present invention is to provide a method for producing a crosslinked acrylic rubber molded article that has improved production efficiency while maintaining rubber-like properties such as compression set. Moreover, it is providing the acrylic rubber composition used for the said manufacturing method. Another object is to provide a sealing material composed of a crosslinked product of the acrylic rubber composition.

  The present inventors have added a porous material as a component of an acrylic rubber composition before molding / crosslinking, so that decomposition products and by-products associated with a reaction at the time of crosslinking adhere to a molding processing apparatus or a mold. Further, they have arrived at the present invention by discovering that they can significantly reduce sticking. The present invention has the following configurations.

  The method for producing a crosslinked acrylic rubber molded article of the present invention is an acrylic rubber containing 100 parts by weight of an acrylic rubber having a crosslinkable group, 0.1 to 30 parts by weight of a porous body, and 0.1 to 10 parts by weight of a diurethane compound. Characterized by shaping and crosslinking the composition.

  The acrylic rubber composition of the present invention contains 100 parts by mass of an acrylic rubber having a crosslinkable group, 0.1 to 30 parts by mass of a porous body, and 0.1 to 10 parts by mass of a diurethane compound.

  In the method for producing a crosslinked acrylic rubber molded article of the present invention and the acrylic rubber composition of the present invention, the crosslinkable group is preferably any one or more selected from a carboxyl group, an epoxy group and a chlorine group. . Further, it is preferable that the porous body is any one or more selected from zeolite, activated clay, activated carbon, bamboo charcoal, and sepiolite. The diurethane compound is preferably 1,6-bis {(9-fluorenylmethyl) carbamate} hexane. Further, it can be used as a sealing material as a crosslinked acrylic rubber molded body.

  INDUSTRIAL APPLICABILITY The method for producing a crosslinked acrylic rubber molded product of the present invention can improve production efficiency while maintaining rubber-like properties such as compression set. Further, the acrylic rubber composition of the present invention is used in the method for producing the crosslinked acrylic rubber molded body. The sealing material of the present invention comprises a crosslinked product of the acrylic rubber composition.

  Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the present invention is not limited to the embodiments described below.

  The method for producing a crosslinked acrylic rubber molded article of the present invention is an acrylic rubber containing 100 parts by weight of an acrylic rubber having a crosslinkable group, 0.1 to 30 parts by weight of a porous body, and 0.1 to 10 parts by weight of a diurethane compound. It is characterized in that the composition is molded and crosslinked. Hereinafter, each component constituting the acrylic rubber composition of the present invention will be described. In the following description, "acrylic rubber having a crosslinkable group" is simply referred to as "acrylic rubber".

(Acrylic rubber)
Acrylic rubber includes acrylic rubber (ACM) and ethylene-acrylic rubber (AEM) in a narrow sense. Acrylic rubber (ACM) in a narrow sense is a polymer obtained by copolymerizing a crosslinkable monomer having a crosslinkable group with an acrylic acid alkyl ester or an acrylic acid alkoxyalkyl ester as a main monomer component. Further, ethylene-acrylic rubber (AEM) is a polymer obtained by copolymerizing a crosslinkable monomer having a crosslinkable group with an acrylic acid alkyl ester and ethylene as main monomer components.

  Examples of the acrylic acid alkyl ester include an acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms. Specifically, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, propyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate. , Stearyl acrylate, etc., preferably methyl acrylate, ethyl acrylate, and n-butyl acrylate.

  Examples of the acrylic acid alkoxyalkyl ester include acrylic acid alkoxyalkyl ester having an alkoxy group having 1 to 4 carbon atoms. Specifically, there are methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, methoxyethoxyethyl acrylate, etc., preferably methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate. Is.

  Examples of the crosslinkable monomer having a crosslinkable group include a crosslinkable monomer having a carboxyl group, an epoxy group, a halogen group, a hydroxyl group, an amide group, or a diene monomer. Specific examples of the crosslinkable monomer having a crosslinkable group include chlorine-based monomers such as 2-chloroethyl vinyl ether and vinyl chloroacetate, epoxy-based monomers such as allyl glycidyl ether, and diene-based monomers such as ethylidene norbornene. Further, as the crosslinkable monomer having a carboxyl group, maleic acid, fumaric acid, itaconic acid, monoalkyl esters such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl of unsaturated dicarboxylic acids such as citraconic acid, acrylic An unsaturated monocarboxylic acid such as an acid or methacrylic acid may, for example, be mentioned. The crosslinkable monomer having these crosslinkable groups is used in the acrylic rubber at a copolymerization ratio of about 0.5 to 10% by mass.

  As the acrylic rubber, an acrylic rubber having a crosslinkable group that is crosslinked with a polyvalent amine is preferable. As the acrylic rubber having a crosslinkable group that is crosslinked with a polyvalent amine, there is an acrylic rubber in which the crosslinkable group is any one or more selected from a carboxyl group, an epoxy group and a chlorine group. Among these, acrylic rubber (ACM) or ethylene-acrylic rubber (AEM) whose crosslinkable group is a carboxyl group is preferable. Examples of commercially available acrylic rubbers (ACM) include AR14 and AR12 manufactured by Nippon Zeon Co., Ltd., and Knoxtite PA-522HF manufactured by Unimatec. Further, examples of commercially available ethylene-acrylic rubber (AEM) include Vamac G and Vamac GLS manufactured by DuPont Dow Elastomers. These acrylic rubbers can be used alone or in combination.

(Diurethane compound)
The diurethane compound reacts with the crosslinkable group of the acrylic rubber and functions as a crosslinking agent of the acrylic rubber. Such diurethane compounds have the general formula:
^{_{R 2 (SO 2) m (}} CH 2) n OCONHR 1 NHCOO (CH 2) n (SO 2) m R 2
There is a diurethane compound represented by. Wherein, R ¹ is a linear or branched divalent aliphatic alkylene group, divalent cycloaliphatic cycloalkylene group or a divalent aromatic group C1 to C20. R ² is a tosyl group or a 2,6-dithiacyclohexyl group. n is an integer of 0 to 2 and m is 0 or 1.

Further, such a diurethane compound has a general formula:
H ₂ N (CH ₂ ) _n NH ₂
The alkylenediamine (n = 4 to 6) represented by each of the amino groups at both ends is replaced by a 9-fluorenylmethyl formate group ((9H-fluoren-9-ylmethoxy) carbonyl group, F _moc group) There is a diurethane compound substituted with. Of these, 1,6-bis {(9-fluorenylmethyl) carbamate} hexane is preferable. 1,6-bis {(9-fluorenylmethyl) carbamate} hexane is a compound represented by the following formula.

  The diurethane compound is added in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the acrylic rubber. The diurethane compound is preferably added in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the acrylic rubber. If the amount of the diurethane compound added is less than 0.1 part by mass, crosslinking will be insufficient and sufficient performance will not be obtained in terms of tensile strength, compression set and the like. On the other hand, if the amount of the diurethane compound added exceeds 10 parts by mass, the elongation at break and the compression set are reduced.

(Crosslinking accelerator)
The diurethane compound as the crosslinking agent is preferably used in combination with a basic crosslinking accelerator as a crosslinking accelerator. As the basic crosslinking accelerator, a guanidine compound, 1,8-diazabicyclo [5.4.0] undecene-7, 1,5-diazabicyclo [4.3.0] nonene-5 and the like are used. It is also possible to use a mixture of 1,8-diazabicyclo [5.4.0] undecene-7 and silica. Examples of commercially available products include Vulcofac ACT55 manufactured by Safic Alcan.

Examples of the guanidine compound include guanidine or a substitution product thereof, and examples thereof include aminoguanidine, 1,1,3,3-tetramethylguanidine, n-dodecylguanidine, methylolguanidine, dimethylolguanidine, 1-phenylguanidine, and 1,3. -Diphenylguanidine, 1,3-di-o-tolylguanidine, triphenylguanidine, 1-benzyl-2,3-dimethylguanidine, cyanoguanidine and the like can be mentioned.
These basic crosslinking accelerators are added in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of acrylic rubber.

(Porous material)
The porous body is a generic term for fillers having a large specific surface area and a large pore volume and having high adsorption ability. The porous body is a filler having a high specific surface area among rubber compounding components and having innumerable pores inside. Depending on the size of the pores, it is classified into a microporous material, a mesoporous material and a macroporous material, but any of them may be used. Specific examples of the porous body include zeolite, activated clay, activated carbon, bamboo charcoal, and sepiolite, and any of them can be preferably used.

  A representative porous material is activated carbon. As a general activated carbon, there is activated carbon produced from a wood-based material by a steam activation method. Commercially available products include those manufactured by Kansai Thermo Chemical Co., Inc., trade name: AMASORB Grade: F-300D and the like. Further, as the activated carbon having higher adsorptivity, there is high-performance porous carbon activated by a chemical such as alkali. Examples of commercially available products include Kansai Thermal Chemical Co., Ltd., trade name: MaxSorb grade: MSP-20. These activated carbons can be used alone or as a mixture.

  The present inventors are able to provide a crosslinked acrylic rubber molded article having improved production efficiency while maintaining rubber-like properties due to the presence of a porous body in the acrylic rubber composition. I found that. That is, due to the presence of the porous body, in the step of molding and crosslinking the acrylic rubber composition, decomposition products and by-products associated with the reaction at the time of crosslinking are fixed to the molding apparatus, and the mold is It has been found that the phenomenon of pollution is significantly reduced.

  The content of the porous body is 0.1 to 30 parts by mass with respect to 100 parts by mass of the acrylic rubber. The production efficiency is improved by adding 0.1 part by mass or more of the porous body to the acrylic rubber. On the other hand, when the porous body is added in an amount of more than 30 parts by mass with respect to the acrylic rubber, the production efficiency is improved to the same extent as when the content is 30 parts by mass, but no significant improvement in the production efficiency is observed and the dough fluidity is improved. , The degree of crosslinking and dispersibility tend to decrease. The content of the porous body is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the acrylic rubber.

  In addition to the above components, known additives such as a reinforcing agent, a filler, an antioxidant, a stabilizer, and a plasticizer may be appropriately added to the acrylic rubber composition. Examples thereof include processing aids such as stearic acid, acid acceptors such as zinc oxide and magnesium oxide, and antiaging agents.

  As carbon black added as a reinforcing agent, soft carbon such as FEF, GPF, SRF and FT is preferable. Common soft carbon is FEF carbon black, and commercially available products include Tokai Carbon Co., Ltd., trade name: SIST G-SO.

(Crosslinked acrylic rubber molding)
In order to produce a cross-linked molded article using acrylic rubber, a predetermined cross-linking agent, a cross-linking accelerator, etc. are added to the acrylic rubber to obtain an acrylic rubber composition, which is molded and cross-linked. The order of the molding step and the crosslinking step of the acrylic rubber composition is not particularly limited, and may be selected according to the shape of the member and the like. The molding step may be performed before the crosslinking step, the crosslinking step may be performed before the molding step, or the molding step and the crosslinking step may be performed at the same time.

  As a kneading machine for preparing an uncrosslinked acrylic rubber composition (rubber compound), a known kneading machine such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, a kneader, or a high shear type mixer can be used. it can. The method and order of addition of each component constituting the acrylic rubber composition to the kneader are not particularly limited.

  The method for molding the crosslinked acrylic rubber molded body is not particularly limited. Any method such as a compression molding method, an injection molding method, an extrusion molding method, or a transfer molding method can be used.

  The cross-linking step of cross-linking the uncross-linked acrylic rubber composition may be performed in one step, or may be performed in two steps of primary cross-linking and secondary cross-linking. By performing the secondary crosslinking after performing the primary crosslinking, it is possible to reliably perform the crosslinking to the inside. The crosslinking conditions are generally pressure crosslinking at about 150-230 ° C. for about 0.5-30 minutes. Secondary crosslinking is generally carried out by oven heating at about 150 to 250 ° C. for about 0.5 to 24 hours.

  The obtained crosslinked acrylic rubber molded article has improved production efficiency during production and maintains rubber-like properties (normal physical properties) such as hardness and compression set.

  The crosslinked acrylic rubber molded article can be widely used in a wide range of fields such as transportation machines such as automobiles, general equipment, electronic and electrical equipment, building members, hoses and the like. Particularly, it is useful as a sealing material such as a gasket, an O-ring, a packing, an oil seal and a bearing seal.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Examples 1-5, Comparative Examples 1-2)
The raw materials of the acrylic rubber composition used in Examples and Comparative Examples are as follows.
Acrylic rubber: AR14, manufactured by Nippon Zeon Co., Ltd., an aliphatic diamine-crosslinked acrylic rubber having a carboxyl group as a crosslinkable group (ACM)
Porous body: manufactured by Kansai Thermochemical Co., Ltd., trade name: Amersault grade: F-300D
Crosslinking agent (diurethane compound): 1,6-bis {(9-fluorenylmethyl) carbamate} hexane Crosslinking accelerator: Vulcofac ACT55 manufactured by Safic Alcan.
Carbon Black: Tokai Carbon Co., Seast G-SO (FEF carbon black)

  The ingredients shown in Table 1 were blended using a kneader and an open roll to prepare a fabric of an acrylic rubber composition. An uncrosslinked rubber sheet having a thickness of about 3 mm was produced from the obtained rubber material by pressing. Then, crosslinking was carried out at a crosslinking condition of 160 ° C. for 30 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Performance of crosslinked rubber sheet>
(1) Hardness It was measured according to JIS K6253-3: 2012.

(2) Compression set Measured according to JIS K6262: 2006.
Test conditions: 150 ° C., 70 hours, test piece: φ29, thickness: 12.5 mm (Plied Disk)

(3) Production efficiency Focusing on the production efficiency associated with the attachment and sticking of decomposition products, the relative evaluation was made in the following four stages.
1: The production efficiency is poor because the decomposition products are fixed. 2: Some decomposition products are fixed, but the production efficiency is good. 3: The decomposition products are hardly fixed, and the production efficiency is good. No sticking of objects and excellent manufacturing efficiency

(4) Dough fluidity The change in Mooney viscosity was measured according to JIS K6300-1. The relative evaluation was carried out in the following three stages.
1: High Mooney viscosity and difficulty in moldability 2: Proper Mooney viscosity and good moldability 3: More appropriate Mooney viscosity, excellent moldability

(5) Degree of cross-linking Based on JIS K6300-2, the change in cross-linking torque was measured, and the relative evaluation was made in the following three stages.
1: Crosslinking speed is slow and moldability is difficult. 2: Crosslinking speed is proper and moldability is good. 3: Crosslinking speed is more proper and moldability is excellent.

(6) Dispersibility In accordance with ASTM D 2663, the dispersity of the porous body was measured, and the relative evaluation was made in the following three stages.
1: poor dispersion, poor quality 2: good dispersion, no major quality problems 3: excellent dispersion, good quality

  The evaluation results of the crosslinked rubber sheet are shown in Table 1.

From the results of Table 1, in the crosslinked rubber sheets of Examples 1 to 5, the numerical values of the compression set did not change so much as compared with Comparative Example 1 in which the porous body was not added. Moreover, the production efficiency is greatly improved as compared with Comparative Example 1 in which the porous body is not added. The performances of the dough fluidity, the degree of crosslinking, and the dispersibility are less changed as compared with Comparative Example 1 in which the porous body is not added.
On the other hand, Comparative Example 1 in which the porous body was not added was inferior in production efficiency. In Comparative Example 2 in which the porous body was excessively added, the production efficiency was excellent, but the performances of the dough fluidity, the degree of crosslinking, and the dispersibility were poor.

Claims (10)

100 parts by mass of acrylic rubber having a crosslinkable group,
A method for producing a crosslinked acrylic rubber molded article, which comprises molding and crosslinking an acrylic rubber composition containing 0.1 to 30 parts by mass of a porous body and 0.1 to 10 parts by mass of a diurethane compound.   The method for producing a crosslinked acrylic rubber molding according to claim 1, wherein the crosslinkable group is at least one selected from a carboxyl group, an epoxy group, and a chlorine group.   The method for producing a crosslinked acrylic rubber molded article according to claim 1 or 2, wherein the porous body is one or more selected from zeolite, activated clay, activated carbon, bamboo charcoal, and sepiolite.   The method for producing a crosslinked acrylic rubber molding according to any one of claims 1 to 3, wherein the diurethane compound is 1,6-bis {(9-fluorenylmethyl) carbamate} hexane. .   The method for producing a crosslinked acrylic rubber molded article according to any one of claims 1 to 4, wherein the crosslinked acrylic rubber molded article is a sealing material.   An acrylic rubber composition containing 100 parts by mass of an acrylic rubber having a crosslinkable group, 0.1 to 30 parts by mass of a porous body, and 0.1 to 10 parts by mass of a diurethane compound.   The acrylic rubber composition according to claim 6, wherein the crosslinkable group is at least one selected from a carboxyl group, an epoxy group, and a chlorine group.   8. The acrylic rubber composition according to claim 6 or 7, wherein the porous body is any one or more selected from zeolite, activated clay, activated carbon, bamboo charcoal, and sepiolite.   The acrylic rubber composition according to any one of claims 6 to 8, wherein the diurethane compound is 1,6-bis {(9-fluorenylmethyl) carbamate} hexane.   A sealing material comprising a crosslinked product of the acrylic rubber composition according to any one of claims 6 to 9.