JPH11116641A - Chloroprene copolymer, its production and adhesive using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject copolymer that can provide an adhesive the extent of discoloration of which is suppressed, when it is stored in a metallic vessel such as a tinplate can, by polymerizing chloroprene and a compound bearing an unsaturated hydrocarbon group and an amino group in its molecule. SOLUTION: This copolymer is prepared by polymerizing (A) 2-chloro-1,3- butadiene (chloroprene) or a combination thereof with a monomer copolymerizable therewith (for example, 2,3-dichloro-1,3-butadiene, styrene, acrylonitrile or the like) and (B) a compound of the formula (X is H, a 1-5C alkyl; (n) is an integer of 1-5; Y is H, a 1-5 C alkyl). The amount of the component B is preferably 0.01-10 pts.wt. per 100 pts.wt. of the total monomers of the components A and B. An emulsion polymerization process is used for this copolymerization. An adhesive composition containing this copolymer can suppress its discoloration, after storage in a tinplate can.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chloroprene copolymer suitable for an adhesive. More specifically, the present invention relates to a chloroprene copolymer (hereinafter, often referred to as chloroprene rubber) which obtains an adhesive whose discoloration degree after storage is significantly suppressed when stored in a metal container such as a tin can.

[0002]

2. Description of the Related Art Chloroprene polymers are used in a wide range of fields such as automobile parts and adhesives, taking advantage of their balanced properties. On the other hand, various attempts have been made to improve the properties of the chloroprene polymer. For example, various chloroprene copolymers obtained by copolymerizing a comonomer component have been proposed. Examples of the comonomer component include sulfur, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, methacrylic acid, and esters thereof. And the like (Rubber Chemistryand Technology, 49 , 670 (1976), etc.). There is also known a method of improving characteristics by grafting a comonomer to a chloroprene polymer (Japanese Patent Publication No. 36845/1988).

[0003] A chloroprene rubber-based adhesive is produced by adding an antioxidant, a metal oxide, a tackifying resin, a solvent, and the like to chloroprene rubber as a raw material rubber. It is known to use a product obtained by graft polymerization of a methyl methacrylate monomer.

However, when the chloroprene rubber-based adhesive prepared as described above is stored in a metal container such as a tin can, there is a problem that the adhesive discolors and deteriorates the quality.

Various measures have been reported to suppress discoloration due to light and heat (JP-A-5-93094, JP-A-7-207070, etc.), but discoloration suppression after storage in a tin container is disclosed. No effective countermeasures were known.

[0006]

SUMMARY OF THE INVENTION The present invention provides a chloroprene copolymer capable of obtaining an improved chloroprene rubber-based adhesive composition, a method for producing the same, and an adhesive composition using the same. Aim. More specifically, the present invention relates to a chloroprene copolymer and a method for producing the same, which can provide an adhesive whose discoloration degree after storage is significantly suppressed when stored in a metal container such as a tin can, and a chloroprene rubber based on the chloroprene copolymer. It is an object to provide an adhesive composition.

[0007]

That is, the present invention provides a method of
-Chloro-1,3-butadiene (hereinafter referred to as chloroprene) or 2-chloro-1,3-butadiene and a monomer copolymerizable therewith, and a compound having an unsaturated hydrocarbon group and an amino group in the molecule And a method for producing the same. Further, an adhesive composition containing the obtained chloroprene copolymer,
An adhesive composition containing the obtained chloroprene copolymer and a specific compound. Further, the present invention relates to a graft copolymer obtained by graft-polymerizing a methacrylate monomer and / or an acrylate monomer to the chloroprene copolymer, and an adhesive composition containing the same. The graft copolymer may contain a polymerization product such as a homopolymer of methacrylic acid ester or acrylic acid ester by-produced by the graft polymerization.

Hereinafter, the present invention will be described in detail. Examples of the monomer copolymerizable with chloroprene used in the present invention include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, sulfur, styrene, acrylonitrile, methacrylonitrile, Examples thereof include isoprene, butadiene, methacrylic acid, acrylic acid, and esters thereof, which can be used as long as the properties inherent in chloroprene are not impaired.

In the present invention, it is essential to use a compound represented by the following general formula (A).

[0010]

Embedded image

(Where X in the general formula (A) is hydrogen or an alkyl group having 1 to 5 carbon atoms, n is an integer of 1 to 5 and Y is hydrogen or an alkyl group having 1 to 5 carbon atoms). Examples include aminomethyl acrylate, aminoethyl acrylate, aminopropyl acrylate, dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate,
Diethylaminomethyl acrylate, diethylaminoethyl acrylate, diethylaminopropyl acrylate, aminomethyl methacrylate, aminoethyl methacrylate, aminopropyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylate,
Examples thereof include diethylaminomethyl methacrylate, diethylaminoethyl methacrylate, and diethylaminopropyl methacrylate. From the viewpoint of reactivity, X is preferably hydrogen or a methyl group. These can be used alone or in combination of two or more.

[0012] The amount of the compound represented by the general formula (A) is the total amount of chloroprene or chloroprene and a monomer copolymerizable therewith and the compound represented by the general formula (A) according to the present invention. To 100 parts by weight of the monomer.
It can be used in the range of from 0.1 to 10 parts by weight, preferably from 0.1 to 5 parts by weight. If the amount is less than 0.01 part by weight, no substantial effect is exhibited, and if it exceeds 10 parts by weight, it is economically disadvantageous.

As a specific means for copolymerizing chloroprene or chloroprene and a monomer copolymerizable therewith with the compound represented by the general formula (A) according to the present invention, for example, a solution weight carried out in a solution is used. Although there are a synthetic method and an emulsion polymerization method performed in an emulsion, an emulsion polymerization method is generally used.

The emulsion polymerization method will be described in more detail.
The emulsifier is not particularly limited, and is generally used for emulsion polymerization of chloroprene, for example, an alkali metal salt of a saturated or unsaturated fatty acid having 6 to 22 carbon atoms, an alkali metal salt of rosin acid or disproportionated rosin acid, For example, an alkali metal salt of a formalin condensate of β-naphthalenesulfonic acid is used. The use amount thereof is preferably in the range of 0.2 to 6 parts by weight based on 100 parts by weight of all the monomers, and within this range, two or more kinds can be used in combination.

The polymerization temperature is from 0 to 0 in consideration of the reactivity of the monomer.
55 ° C is preferred. As the polymerization initiator, known organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide and t-butyl hydroperoxide are used.

The polymerization is carried out at a conversion of 40 to 95%, preferably 5 to 95%.
The polymerization is carried out in the range of 0 to 85%, and then the polymerization is terminated by adding a small amount of a polymerization inhibitor. Examples of the polymerization inhibitor include thiodiphenylamine, 4-tert-butylcatechol, 2,2-methylenebis-4-methyl-6-tert-butylphenol, and 4,4′-methylenebis- (2,6-di-t- Butylphenol),
2,2′-methylenebis- (4-methyl-6-cyclohexylphenol) and the like are used. Unreacted monomers are removed by, for example, a steam stripping method. Thereafter, the pH of the latex is adjusted to 5.5 to 7.5, and the polymer is subjected to ordinary freeze coagulation, water washing, hot air drying, and the like. Can be isolated.

Further, from the viewpoint of more remarkably or synergistically suppressing the discoloration of the adhesive containing the chloroprene copolymer or the graft copolymer according to the present invention after storage in a tin can, a piperidyl group is contained in the molecule. Piperidine-2-carboxylic acid, piperidine-3-
Carboxylic acid, piperidine-4-carboxylic acid, (2,2,
6,6-tetramethyl-4-piperidyl) sebacic acid,
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (4-piperidyl) sebacate,
(2,2,6,6-tetramethyl-4-piperidyl) azelaic acid, bis (2,2,6,6-tetramethyl-4)
-Piperidyl) azelate, bis (4-piperidyl) azelate, (2,2,6,6-tetramethyl-4-piperidyl) adipic acid, bis (2,2,6,6-tetramethyl-4-piperidyl) adipate , Bis (4-piperidyl) adipate, (2,2,6,6-tetramethyl-
4-piperidyl) oleic acid, (1,2,2,6,6-
Pentamethyl-4-piperidyl) sebacic acid, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, (1,2,2,6,6-pentamethyl-4-piperidyl) azelaic acid, bis (1, 2, 2,
6,6-pentamethyl-4-piperidyl) azelate,
(1,2,2,6,6-pentamethyl-4-piperidyl) adipate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) adipate, (1,2,2
6,6-pentamethyl-4-piperidyl) oleic acid,
Bis (1,2,2,6,2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate
6-pentamethyl-4-piperidyl), N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4- Piperidyl) amino] -6-chloro-1,
3,5-triazine condensate, dimethyl succinate 1-
(2-hydroxyethyl) -4-hydroxy-2,2,
6,6-tetramethylpiperidine polycondensate, poly [$ 6
-(1,1,3,3-tetramethylbutyl) amino-
1,3,5-triazine-2,4-diyl {(2,
2,6,6-tetramethyl-4-piperidyl) imino}
Hexamethylene ｛(2,2,6,6-tetramethyl-4
-Piperidyl) imino}].

For the purpose of suppressing the light discoloration resistance, benzotriazole compounds such as 2- (5-methyl-2-hydroxyphenyl) benzotriazole and 2- [2-hydroxy-3,5-bis- (α, α -Dimethylbenzyl)
Phenyl] -2H-benzotriazole, 2- (3,5
-Di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-)
(Hydroxyphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenol) -5-chlorobenzotriazole, 2- (2
-Hydroxy-3-t-butyl-5-methylphenol) -5-chlorobenzotriazole, 2- (3,5-
Di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2-
(2-hydroxy-5-t-octylphenyl) benzotriazole and the like may be added.

The chloroprene polymer or chloroprene copolymer (hereinafter referred to as chloroprene rubber) obtained by the above-described method is added to a methacrylic acid ester monomer and / or
Alternatively, as a method for producing a graft copolymer obtained by graft polymerization of an acrylate monomer, a methacrylate monomer and / or an acrylate monomer are added to a solution in which chloroprene rubber is dissolved in an organic solvent,
A solution polymerization method in which graft polymerization is performed on chloroprene rubber in the presence of a radical initiator is generally used. However, a methacrylate monomer and / or
Alternatively, an emulsion polymerization method in which an acrylate monomer is added and graft polymerization is performed in the presence of a radical initiator can also be used. Examples of the methacrylate include, for example, methyl methacrylate, ethyl methacrylate, and propyl methacrylate, and examples of the allylic ester include methyl acrylate, ethyl acrylate, and propyl acrylate. Methyl acid is preferably used.

The adhesive using the chloroprene rubber according to the present invention may contain other additives other than those described above, an antioxidant, a resin, a stabilizer, a plasticizer, a solvent, etc. as long as the properties are not impaired. Good.

[0021]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited by these examples. In the following description, parts and% are indicated by weight.

Example 1 Using a reactor having an internal volume of 10 liters, an emulsion was prepared in the composition ratio shown in Table 1, and potassium persulfate was used as an initiator.
Polymerization was carried out at 10 ° C. in a nitrogen atmosphere. When the conversion reached 70%, an emulsion of phenothiazine was added as a polymerization inhibitor to terminate the polymerization. Next, unreacted monomers were removed by a conventional steam stripping method, and chloroprene rubber was obtained from the obtained latex by a conventional freeze-drying and coagulation method. A portion of the chloroprene rubber was purified using benzene and methanol, and the nitrogen content in the polymer was determined by the Kjeldahl method. From this value, the nitrogen mol% present in the polymer was calculated. The nitrogen content in the polymer was determined in the same manner in the following examples.

15 parts by weight of the obtained chloroprene rubber was dissolved in 85 parts by weight of toluene, and this was used for a storage test in a tin can.

The determination of the degree of discoloration after storage in the tin can was performed as follows. As the tin can, a 300 cc capacity uncoated epoxy tin can manufactured by Saitama Can Co., Ltd. was used. The toluene solution prepared in Example 1 was put in a tin can and the lid was closed. After heating at 70 ° C. for 2 days, a change in color tone and a state of discoloration of the inner wall of the tin can were observed. The color tone of the toluene solution is measured by the Lab method (reflection method) using a colorimetric colorimeter (model # 80) manufactured by Nippon Denshoku Industries Co., Ltd., and the color difference ΔE is determined from the measured values before and after storage, and judgment is made based on the magnitude. did. Changes in the tin can inner wall were visually observed.

The adhesion test sample was prepared by adding 20 parts by weight of an isopropenyl toluene resin (FTR-612 manufactured by Mitsui Petrochemical Co., Ltd.) to 100 parts by weight of chloroprene rubber.
5) was added, dissolved, This solution was stirred added 5 parts by weight of the isocyanate Desmodur RFE (Bayer) per 100 parts by weight, and 200 g / m ² applied to soft salt Bireza as an adherend, After 30 minutes of the open time, they were joined, and were reciprocated 5 times with a 10-lb rubber roller to produce a press-fit. All operations were performed at room temperature. The adhesive strength was measured using the above-mentioned bonded body after a set time of 7 days using a Tensilon type tensile tester (manufactured by Shimadzu Corporation) at a tensile speed of 50 mm / min.

Examples 2 to 5 In the same manner as in Example 1, emulsion polymerization and post-treatment were carried out according to the recipe shown in Table 1 to obtain chloroprene rubber. Next, after dissolving 100 parts by weight of chloroprene rubber in 600 parts by weight of toluene, 75 parts by weight of methyl methacrylate (MMA) are mixed and heated to 85 ° C. with stirring, and then 0.5 parts by weight of benzoyl peroxide. Was added and graft copolymerized for 5 hours. Then, 0.5 part by weight of hydroquinone was added to stop the polymerization reaction to obtain a graft copolymer (hereinafter, referred to as graft paste). This graft paste was used for a storage test. An adhesion test sample was prepared by mixing isopropenyl toluene resin and isocyanate desmodule RFE with 100 parts by weight of the graft paste in the same procedure as in Example 1, and applying the mixture to an adherend.

Example 6 After a graft copolymer was obtained in the same manner as in Examples 2 to 5, N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl- N- (1,
When 2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate is added and dissolved in 0.3 parts by weight per 100 parts by weight of the graft copolymer. It is.

Example 7 After a graft copolymer was obtained in the same manner as in Example 3, 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid was obtained. Screws (1, 2, 2,
6,6-pentamethyl-4-piperidyl) was added and dissolved in 0.3 parts by weight per 100 parts by weight of the graft copolymer.

Example 8 A graft copolymer was obtained in the same manner as in Example 7, and then N, N'-bis (3
-Aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,3
0.3 part by weight of 5-triazine condensate per 100 parts by weight of graft copolymer, and 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole as a benzotriazole compound To 0.
This is the case where 3 parts by weight are added and dissolved.

[0030]

[Table 1]

Comparative Example 1 A chloroprene polymer was obtained in the same manner as in Example 1 except that the compound represented by the above general formula (A) was not contained at the composition ratios shown in Table 2, and evaluated in the same manner. Are shown in Table 2.

Comparative Example 2 A chloroprene polymer and a graft copolymer were prepared in the same manner as in Examples 2, 3 and 4 except that the compound represented by the above general formula (A) was not contained at the composition ratios shown in Table 2. A polymer was obtained and evaluated in the same manner, and the results are shown in Table 2.

Comparative Example 3 A chloroprene polymer and a graft copolymer were obtained in the same manner as in Example 5 except that the compound represented by the above formula (A) was not contained at the composition ratios shown in Table 2. Table 2 shows the evaluation results.

[0034]

[Table 2]

As can be seen from the results of Tables 1 and 2, the adhesive containing the chloroprene copolymer or the graft copolymer according to the present invention has little discoloration after storage in a tin can and has excellent properties. You can see that.

[0036]

As described above, according to the method for producing a chloroprene copolymer of the present invention, it is possible to obtain a chloroprene copolymer and a graft copolymer thereof having little discoloration after being stored in a tin can or the like. The adhesive containing the chloroprene copolymer or the graft copolymer has excellent storage stability when stored in a tin can and is extremely useful industrially.

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Claims (8)

[Claims] 1. 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene) or 2-chloro-1,3-butadiene.
A chloroprene copolymer obtained by polymerizing butadiene, a monomer copolymerizable therewith, and a compound represented by the following general formula (A). Embedded image (However, X in the general formula (A) is hydrogen or carbon number 1 to
An alkyl group of 5, n is an integer of 1 to 5, Y is hydrogen or an alkyl group of 1 to 5 carbon atoms) 2. The chloroprene copolymer according to claim 1, wherein X in the general formula (A) is hydrogen or a methyl group. 3. A method for producing a chloroprene copolymer, comprising copolymerizing chloroprene or chloroprene and a monomer copolymerizable therewith with a compound represented by the general formula (A). 4. A graft copolymer obtained by graft-polymerizing a methacrylate monomer and / or an acrylate monomer onto the chloroprene copolymer according to claim 1. 5. An adhesive composition comprising the chloroprene copolymer according to claim 1. 6. An adhesive composition comprising the graft copolymer according to claim 4. 7. The adhesive composition according to claim 5, comprising a piperidyl group-containing compound. 8. The adhesive composition according to claim 7, further comprising a benzotriazole compound.