JP2007231129A - Sealing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing agent for rubber members rapidly repairing a leakage part of gas without exchanging piping and excellent in storage stability and sealing property. <P>SOLUTION: The sealing agent comprises 40-90 wt.% aliphatic conjugated diene monomer unit and contains ≤50 wt.% content which is insoluble in toluene. The sealing agent comprises, further, a polymerization inhibitor or an antioxidant in a specific amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealing agent for sealing a rubber member.

  Conventionally, in order to transfer gas, rubber piping which is a rubber member has been used because it is flexible and can transfer gas to various places. These rubber pipes change the connection position according to the place where they are used, so they repeatedly expand and contract, deteriorate over time, and in some cases contact sharp points, resulting in fine cracks and pins. May cause holes. When such cracks or pinholes occur, it is necessary to temporarily stop the transfer gas in order to replace the rubber pipe, and after replacing the rubber pipe, it is necessary to replace the inside of the pipe with the transfer gas, resulting in poor workability. It was a thing.

  In view of this, attempts have been made to repair the piping from the inside without replacing the rubber piping. For example, Patent Document 1 discloses a liquid sealant mainly composed of an emulsion having a particle size distribution. However, in order to obtain a desired particle size distribution, it is necessary to separately prepare emulsions having different particle sizes and then mix them, which is troublesome, and the airtightness after repair is insufficient.

JP 2000-63798 A

  In view of the above circumstances, the object of the present invention is to provide a rubber member sealing agent capable of quickly repairing a gas leakage portion without exchanging rubber piping, and having excellent storage stability and sealing properties. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found that the aliphatic conjugated diene monomer unit is contained in an amount of 40 to 90% by weight and the toluene insoluble content is 50% by weight or less. It has been found that if the latex of the copolymer is used as a sealing agent, the gas leakage part can be repaired quickly without exchanging rubber piping, and the storage stability and sealing performance are excellent. Based on this finding, the present invention has been completed.

Thus, according to the present invention, the following inventions 1 and 2 are provided.
1. A sealing agent comprising a latex of a copolymer comprising 40 to 90% by weight of an aliphatic conjugated diene monomer unit and having a toluene insoluble content of 50% by weight or less.
2. 2. The sealing agent according to 1 above, further comprising 0.05 parts by weight or more of a polymerization inhibitor or an anti-aging agent with respect to 100 parts by weight of the solid content of the copolymer latex.

  According to the present invention, it is possible to provide a sealing agent that can quickly repair a leaked portion without exchanging piping and that is excellent in storage stability and sealing performance.

Hereinafter, the present invention will be described in detail.
(Copolymer latex)
The copolymer latex used in the sealing agent of the present invention contains 40 to 90% by weight of an aliphatic conjugated diene monomer unit, and has a toluene insoluble content of 50% by weight or less. The latex.
The copolymer latex used in the present invention is obtained by polymerizing an aliphatic conjugated diene monomer and another monomer copolymerizable with the aliphatic conjugated diene monomer.

Examples of the aliphatic conjugated diene monomer used in the present invention include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-ethyl-1. , 3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, and the like. Among these, 1,3-butadiene is preferable in terms of excellent sealing properties.
The amount of the aliphatic conjugated diene monomer unit in the entire copolymer is 40 to 90% by weight, preferably 60 to 80% by weight. When this amount is in the above range, the sealing property is excellent.

  As the monomer copolymerizable with the aliphatic conjugated diene monomer of the present invention, styrene, α-methylstyrene, p-methylstyrene, p-phenylstyrene, p-methoxystyrene, chloromethylstyrene, m- Aromatic vinyl monomers such as fluorostyrene, vinylnaphthalene, p-styrenesulfonic acid and its sodium and potassium salts; acrylonitrile, methacrylonitrile, 2-ethylpropenenitrile, 2-propylpropenenitrile, 2-chloropropenenitrile , Ethylenically unsaturated nitrile monomers such as 2-butenenitrile; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) Dodecyl acrylate, glycidyl (meth) acrylate, (meth) a Ethylenically unsaturated carboxylic acid ester monomers such as acrylic acid dimethylaminoethyl;

  Ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid and crotonic acid; ethylenically unsaturated polycarboxylic acid monomers such as fumaric acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride And its anhydrides; partial ester monomers of polyvalent carboxylic acids such as butyl maleate and butyl itaconate; olefinic monomers such as ethylene, propylene, 1-butene and isobutene;

  Vinyl ether monomers such as methyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether; allyl compounds such as allyl acetate, methallyl acetate, allyl chloride, methallyl chloride; Vinyl silyl compounds such as vinyl trimethoxysilane; vinyl heterocyclic compounds such as vinyl pyridine and N-vinyl pyrrolidone; carboxylic acid vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, isopropenyl acetate; And vinyl halide monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride.

  These copolymerizable monomers can be used alone or in combination of two or more. Among these, an aromatic vinyl monomer is preferable and a styrene monomer is particularly preferable in terms of high compatibility with the rubber to be repaired and excellent sealing properties.

  The amount of the monomer unit composed of a monomer copolymerizable with the aliphatic conjugated diene monomer in the copolymer is 10 to 60% by weight, preferably 20 to 40% by weight.

The toluene insoluble content of the copolymer constituting the copolymer latex used in the present invention is essentially 50% by weight or less, preferably 30% by weight or less, and particularly preferably 10% by weight or less.
Examples of the method for adjusting the amount of insoluble toluene in the above range include a method for appropriately adjusting the amount of the molecular weight regulator used; a method for appropriately adjusting the polymerization temperature; and a method for reducing the polymerization conversion rate.
These methods can be used alone or in combination of two or more.

  The glass transition temperature of the copolymer constituting the copolymer latex is preferably -70 to 0 ° C, more preferably -60 to -30 ° C. The glass transition temperature of the polymer can be appropriately adjusted depending on the kind and amount of the monomer used for the polymerization.

Examples of the molecular weight modifier include alkyl mercaptans such as tert-dodecyl mercaptan and n-dodecyl mercaptan, carbon tetrachloride, thioglycols, diterpenes, terpinolene, γ-terpinenes and α-methylstyrene dimer.
The amount of the chain transfer agent used may be appropriately determined in order to adjust the toluene-insoluble content of the finally obtained copolymer latex, but it is 0 to 10 weights with respect to 100 parts by weight of the polymerizable monomer. Part is preferable, and 0.01 to 5 parts by weight is more preferable.

  The polymerization temperature is preferably 90 ° C. or lower, more preferably 60 ° C. or lower, and particularly preferably 30 ° C. or lower. The polymerization time is usually 30 minutes to 50 hours.

  The copolymer latex used in the present invention can be polymerized by using a conventionally known emulsion polymerization method using the above monomers. For example, a monomer is dispersed in water with a surfactant and polymerized by adding a polymerization initiator, a chelating agent, an oxygen scavenger, a molecular weight adjusting agent, or the like. In addition, conventionally well-known each chemical | medical agents can be used for superposition | polymerization chemical | medical agents, such as surfactant, a polymerization initiator, a chelating agent, and an oxygen scavenger used in the said emulsion polymerization.

  Although it does not specifically limit as a polymerization initiator, For example, water-soluble peroxides, such as potassium persulfate, ammonium persulfate, and hydrogen peroxide; Diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydro And oil-soluble peroxides such as peroxide and di-t-butyl peroxide; redox polymerization initiators that are used in combination of an oxidizing agent and a reducing agent containing a transition metal ion. Among these, a redox initiator is preferably used because it is easy to adjust the toluene-insoluble content of the copolymer.

  As the reducing agent, for example, ascorbic acid, sodium ascorbate, ascorbic acid (salt) of potassium ascorbate; erythorbic acid, sodium erythorbate, erythorbic acid (potassium erythorbate); saccharides; sodium formaldehyde sulfoxylate Sodium sulfite, potassium sulfite, sodium hydrogen sulfite, potassium bisulfite sulfite; Sodium pyrosulfite, potassium pyrosulfite, sodium pyrobisulfite, potassium pyrosulfite pyrosulfite; Sodium thiosulfate, thiosulfate Thiosulfate of potassium; phosphorous acid, sodium phosphite, potassium phosphite, sodium hydrogen phosphite, potassium hydrogen phosphite (salt); pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, Sodium phosphite hydrogen, pyrophosphorous acid (salt) pyrophosphoric hydrogen phosphite potassium; and the like. Of these, sodium formaldehyde sulfoxylate is preferable.

Examples of transition metal ions include copper ions, iron ions, cobalt ions, nickel ions, and the like. In order to stabilize the transition metal ion in water, a chelating agent is used, for example, an alkali metal salt of ethylenediaminetetraacetic acid and acetylacetone. Among them, an iron complex of ethylenediaminetetraacetic acid that can form a stable metal complex is used. preferable.
The amount of initiator is preferably from 0.01 to 3% by weight, based on the total weight of the monomer, and in a redox system, the amount of reducing agent is preferably 0.00 based on the total weight of the monomer. 01 to 3% by weight.

  The polymerization reaction can be stopped by adding a known polymerization terminator to the reaction system or by cooling the reaction system. The polymerization conversion rate when stopping the polymerization reaction is preferably 95% or less, more preferably 90% or less, and particularly preferably 85% or less. After the polymerization is completed, a post-treatment such as removing unreacted monomers can be performed as necessary to obtain a copolymer latex.

  The weight average particle diameter of the copolymer constituting the copolymer latex is usually 30 to 1,000 nm, preferably 80 to 250 nm. If the particle size is too small, the viscosity of the latex becomes high and it becomes difficult to prepare a sealing agent. On the other hand, if the particle size is too large, the sealing property may be lowered.

The sealing agent of the present invention preferably further contains a polymerization inhibitor and an anti-aging agent. The addition amount of the polymerization inhibitor and the antioxidant is preferably 0.05 parts by weight or more, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the copolymer.
Examples of the polymerization inhibitor include compounds that trap radicals to generate stable radicals and inhibit or suppress polymerization. For example, N, N-diethylhydroxylamine, N-nitrosodiphenylamine, 2,4-dinitrophenylhydrazine , P-phenylenediamine, phenothiazine, 1,1-diphenyl-2-picrylhydrazyl, alloocimene, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, triethylphosphite, 4-nitrosophenol, 2-nitrophenol, p-aminophenol, 4-hydroxy TEMPO (known as 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy free radical), Droquinone, p-methoxyhydroquinone, t-butyl-p-hydroquinone, 2,5-di-t-butyl-p-hydroquinone, 1,4-naphthalenediol, 4-t-butylcatechol, copper sulfate, copper nitrate, cresol And phenol and diphenylamine derivatives.

  It is preferable that the usage-amount of these polymerization inhibitors is 0.01-3.0 weight part with respect to 100 weight part of solid content of copolymer latex. If the amount used is too small, the toluene insoluble matter tends to be high when removing the unreacted monomer, and conversely if too large, the copolymer latex may be colored.

  The sealing agent of the present invention particularly preferably contains an anti-aging agent. Examples of the antioxidant include compounds having a radical chain inhibiting action, compounds having a peroxide decomposing action, and the like.

  Compounds having a radical chain inhibiting action are mainly classified into phenolic compounds and aromatic amine compounds. Examples of phenolic compounds include monophenol compounds, bis, tris, polyphenol compounds, and thiobisphenol compounds. Specific examples of the monophenol compound include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,4-dioctylphenol, butylhydroxyphenol, 2,6. -Di-t-butyl-α-dimethylamino-p-cresol, butylated octylated phenol, etc., and the system is 2,2′-methylene-bis- (6-α-methyl) as bis, tris and polyphenol compounds. -Benzyl-p-cresol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), p-cresol 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxyl) Benzyl) benzene, modified polyalkyl phosphited polyhydric phenols, etc., and thiobisphenol compounds include 4,4′-thiobis- (6-tert-butyl-3-methylphenol), 4,4′-thiobis. -(6-t-butyl-o-cresol) and the like.

  Aromatic amine compounds include naphthylamine compounds, diphenylamine compounds, p-phenylenediamine compounds, and the like. Specific examples thereof include phenyl-α-naphthylamine, phenyl-β-naphthylamine, aldol-α-naphthylamine, and the like as naphthylamine compounds. Examples of diphenylamine compounds include p-isopropoxy diphenylamine, N, N′-diphenyl, There are ethylenediamine, octylated diphenylamine and the like, and p-phenylenediamine compounds include N, N′-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, N, N′-bis ( And 1-methylheptyl) -p-phenylenediamine.

  Specific examples of the compound having a peroxide decomposing action include tris (nonylphenyl) piping phyto, dilauryl thiodipropionate, 2-mercaptobenzimidazole, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate and the like. Can be mentioned. These peroxide decomposing agents are called secondary anti-aging agents and are not effective by themselves, and can be enhanced by using in combination with a radical chain inhibitor that is a primary anti-aging agent.

  These antioxidants are preferably liquid at 23 ° C., more preferably an aromatic amine compound, and a diphenylamine compound can be most preferably used. These anti-aging agents may be used alone or in combination of two or more.

  The addition amount of these anti-aging agents is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and particularly preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the copolymer. preferable.

  The sealing agent of the present invention may contain additives such as preservatives and antibacterial agents other than the polymerization inhibitor and the anti-aging agent. For such additives such as preservatives and antibacterial agents, conventionally known additives can be used.

  The sealing agent of the present invention further includes antifreezing agents such as ethylene glycol and propylene glycol; fibers such as polypropylene, polyester, polyethylene and nylon; smectite (including montmorillonite (bentonite)), attapulgite and kaolin Clay thickeners such as (kaolinite); clay modified with organic matter such as organic bentonite clay made by reacting smectite with quaternary ammonium organic compound; metal particles such as Ti; metal oxide particles and calcium carbonate An inorganic filler such as The amount of these components used, the blending method, and the like are appropriately selected within a range that does not impair the object of the present invention.

  Although the sealing agent of this invention can be used suitably for piping which is rubber members, such as a rubber hose, if it is a rubber member, it will not be limited to piping, and can also be used for other rubber members, such as a rubber sheet.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. Further, parts and% in these examples are based on weight unless otherwise specified.
The evaluation method will be described below.

(1) Weight average particle diameter (nm)
The weight average particle diameter of the polymer latex was measured with Coulter LS230 (Culter particle diameter measuring machine).

(2) Toluene-insoluble matter About 2 g of copolymer latex was added dropwise to 150 ml of stirred ethanol to coagulate the copolymer latex. The obtained coagulated product was filtered off with a filter paper, and further washed with an ethanol solution (about 100 ml) containing 0.05% diethylhydroxyamine. Subsequently, it vacuum-dried on 30 degreeC and the conditions for 24 hours, and obtained the dry coagulum. About 0.15 g from this dried coagulum is precisely weighed and placed in an 80-mesh wire mesh basket, immersed in 60 ml of toluene at 20 ° C. for 48 hours, and then the coagulum remaining in the wire mesh cage is decompressed at 100 ° C. After drying, the residual rate was calculated to obtain the toluene insoluble matter.
(3) Glass transition temperature A copolymer latex is cast on a framed glass plate, left in a constant temperature and humidity chamber at a temperature of 20 ° C. and a relative humidity of 65% for 48 hours, and dried to form a film of the copolymer latex. Obtained.
The glass transition temperature of the film was measured using a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd .: SSC5200) under the conditions of a starting temperature of −100 ° C. and a heating rate of 5 ° C./min.
(Copolymer latex)

(Production Example 1)
In a pressure-resistant reaction vessel equipped with a stirrer and a thermometer, 30 parts of styrene, 70 parts of butadiene, 3.5 parts of potassium oleate, 0.03 part of t-dodecyl mercaptan, 0.7 part of potassium chloride, ethylenediaminetetraacetic acid 0.05 parts of sodium, 0.05 parts of sodium formaldehyde sulfoxylate, 0.003 parts of ethylenediaminetetraacetic acid iron and 135 parts of ion-exchanged water were charged, mixed under stirring and cooled to 5 ° C. Subsequently, 0.05 parts of diisopropylbenzene hydroperoxide was added, and the reaction was continued until the polymerization conversion was 80%. Thereafter, 0.02 part of potassium hydroxide and 0.02 part of sodium dimethyldithiocarbamate as a polymerization inhibitor were added to stop the reaction. Thereafter, 3.5 parts of potassium oleate, an antifoaming agent, and 100 parts of ion-exchanged water were added, followed by concentration to a solid concentration of 40%, and a diphenylamine compound (Antage OD, manufactured by Kawaguchi Chemical Co., Ltd.) 0.5 Part was added to obtain a copolymer latex A. Copolymer latex A had a toluene insoluble content of 5%. The glass transition temperature was -47 ° C.

(Production Example 2)
A copolymer latex B was obtained in the same manner as in Production Example 1 except that t-dodecyl mercaptan was not used. The toluene insoluble content of copolymer latex B was 75%.
(Production Example 3)
A copolymer latex C was obtained in the same manner as in Production Example 1 except that no diphenylamine compound was added.

(Seal performance evaluation)
A rubber pressure-resistant pipe (HP air pipe inner diameter 19 mm, outer diameter 30 mm, length 1 m) was drilled at three locations with a 3 mm diameter nail, and after removing the nail, 200 ml of a sealing agent was injected, The pressure was increased to 1 kPa with air and left for 1 minute. The sealing agent was discharged from the pipe, and after 10 minutes, it was determined whether or not the nail hole was closed.

Example 1
55 parts of copolymer latex A, 15 parts of tackifier resin emulsion (Nanolet R1050 manufactured by Yasuhara Chemical Co., Ltd.) and 30 parts of ethylene glycol were mixed to obtain a sealing agent. Using the obtained sealant, the sealing performance was immediately evaluated. As a result, no gas leaked from any of the nail holes, and the sealing performance was good.

(Example 2)
The obtained sealing agent was allowed to stand at 80 ° C. for 10 days, and then the sealing performance was evaluated in the same manner as in Example 1 except that the sealing performance test was performed. Gas did not leak and the sealing performance was good.

(Comparative Example 1)
The sealing performance was evaluated in the same manner as in Example 1 except that the copolymer latex A was changed to the copolymer latex B. As a result, gas leaked from any nail hole.
(Comparative Example 2)
The sealing performance was evaluated in the same manner as in Example 2 except that the copolymer latex A was changed to the copolymer latex C. As a result, gas leaked from any nail hole. Here, after the copolymer latex C was allowed to stand at 80 ° C. for 10 days, the toluene insoluble content of the copolymer was 77%.

Claims (2)

  A sealing agent comprising a latex of a copolymer comprising 40 to 90% by weight of an aliphatic conjugated diene monomer unit and having a toluene insoluble content of 50% by weight or less. The sealing agent according to claim 1, further comprising 0.05 parts by weight or more of a polymerization inhibitor or an anti-aging agent with respect to 100 parts by weight of the solid content of the copolymer latex.