JPH08188761A - Latex for heat resistance-improved adhesive and chloroprene-based adhesive composition using the same - Google Patents

Abstract

PURPOSE: To obtain the subject latex having excellent adhesive properties such as normal temperature adhesion, high-temperature adhesion and water resistance, stability of latex and heat-resistant creeping property by blending two chloroprene rubber latexes having different solution viscosity. CONSTITUTION: The objective latex is composed of a blend of (A) a chloroprene rubber latex as a solution dissolved in 5% chloroform not containing an insoluble part in an organic solvent and having >=2000mPa. s solution viscosity and (B) a chloroprene rubber latex having <=2000mPa. s solution viscosity. Preferably, a mixing ratio of the component (A:B) is (30:70)-(5:95) in a dry weight ratio of the polymers. The chloroprene latex is preferably obtained by a radical emulsified copolymerization of 100 pts.wt. of chloroprene with 0.1-10 pts.wt. of methacrylic acid in the presence of an emulsifying/dispersing agent at 8-40 deg.C. The solution viscosity may be controlled by adjusting an adding amount of chain transfer agent such as n-dodecyl mercaptan.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a latex for heat resistance improving adhesives, wherein a 5% chloroform solution of the polymer is a solution containing no organic solvent insoluble portion and the solution viscosity is different.
The present invention relates to a latex for adhesives, which comprises a mixture of chloroprene rubber latex of at least one kind, and an adhesive composition using the same. More specifically, a latex having a solution viscosity of 2000 mPa · s or more of the polymer is admixed with a chloroprene rubber latex as an essential component, whereby heat resistance, particularly heat-resistant creep resistance can be dramatically improved. And an adhesive composition using the same.

[0002]

2. Description of the Related Art A method for producing a copolymer latex of chloroprene and a vinyl monomer having a carboxyl group such as acrylic acid and methacrylic acid is disclosed in JP-A-61-1271.
No. 0, JP-A-62-257918 and the like. For a method for producing a latex for an adhesive using a water-soluble polymer such as polyvinyl alcohol as an emulsifying / dispersing agent and an adhesive using the latex, see JP-B-52.
It is known from No. 13983 and Japanese Patent Publication No. 61-29968.

[0003]

However, when the latex produced by these methods is used alone, there are the following problems.

1) A latex containing the copolymer obtained by one-time polymerization using a chain transfer agent alone cannot obtain sufficient adhesive properties. For example, a 5% chloroform solution is a solution that does not contain an organic solvent insoluble part and has a solution viscosity of 5
The copolymer alone having a viscosity of 00 mPa · s or more does not satisfy the room temperature strength, and the 5% chloroform solution is a solution containing no organic solvent insoluble part and has a solution viscosity of 50.
The copolymer alone having a viscosity of 0 mPa · s or less is inferior in heat resistance represented by high temperature peel strength and the like.

2) A tackifier which is an essential subcomponent of a chloroprene adhesive when it is produced by using an emulsifier having good latex stability in a high pH range such as an alkali metal rosin acid salt. Since rubber deposits due to slight fluctuations in pH when compounding metal oxides and the like, the pH must be adjusted very carefully, which is troublesome in operation. In addition, when a water-soluble polymer such as polyvinyl alcohol is used for the production, the protective colloid property shows excellent latex stability, but the water resistance when used as an adhesive is significantly reduced. .

Further, it has not always been said that it is always sufficiently satisfactory for applications in which only certain specific physical properties are desired to be made extremely good. For example, further improvement was required to meet the demand for heat resistance, particularly heat creep resistance.

The present invention has been made in view of the above problems, and its purpose is to provide adhesive properties such as room temperature adhesive strength, high temperature adhesive strength, and water resistance which cannot be obtained by conventional latex adhesives. An object of the present invention is to provide a latex for an adhesive, which has good latex stability and excellent heat resistance, in particular, heat and creep resistance, and an adhesive composition using the same.

[0008]

The inventors of the present invention have completed the present invention as a result of earnest studies for solving the above problems based on such a background. That is, the present invention is a chloroprene rubber latex in which a 5% chloroform solution is a solution containing no organic solvent insoluble portion and a solution viscosity of 2000 mPa · s or more, and a solution viscosity of 2000 mPa · s.
The present invention relates to a latex for a heat resistance improving adhesive, which is composed of a mixture with a chloroprene rubber latex having a s or less, and an adhesive composition using the same.
In particular, at a certain constant mixing ratio, other adhesive properties can be sufficiently satisfied while maximizing the heat resistant creep resistance. Furthermore, when the chloroprene rubber latex is a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer, the physical properties can be further improved.

The present invention will be described in more detail below.

The latex for heat-resistant adhesive in the present invention is a chloroprene rubber latex in which a 5% chloroform solution is a solution containing no organic solvent-insoluble portion and the solution viscosity is 2000 mPa · s or more, and the solution viscosity is 2000.
It is composed of a mixture with chloroprene rubber latex having a mPa · s or less. Here, that the 5% chloroform solution is a solution containing no organic solvent insoluble portion and has a solution viscosity of 2000 mPa · s or more means, for example, using a B-type viscometer, 12 rpm, 60 rpm under a temperature condition of 23 ° C. No. As a result of measurement in a 3 rotor, it means that the solution viscosity is 2000 mPa · s or more,
On the other hand, the solution viscosity of 2000 mPa · s or less means that
As a result of the same method, the solution viscosity was 2000 mP.
It is a · s or less.

On the other hand, the solution viscosity is 2000 mPa.
A chloroprene rubber latex of s or more alone has insufficient room temperature strength and a solution viscosity of 2000 mPa · s.
The following chloroprene rubber latex alone is insufficient in heat resistance such as high temperature peel strength and heat creep resistance.

As described above, the latex for heat resistance-improving adhesive of the present invention is obtained by mixing chloroprene rubber latex having a solution viscosity in a specific range which can be controlled by adjusting the addition amount of the chain transfer agent. However, the average molecular weight of the polymer is not limited.

The dry weight ratio of the polymer to be mixed is not particularly limited as long as the heat creep resistance is satisfied, but it is preferable that the solution viscosity of a 5% chloroform solution is 2000 mPa · s or more. The dry weight ratio of the polymer of the rubber latex and the chloroprene rubber latex having a solution viscosity of 2000 mPa · s or less is 50:50 to 1:99, and more preferably 30:70 to 5:95. Is. Within this range, the latex has extremely improved heat-resistant creep resistance and can maintain a sufficient room-temperature adhesive strength.

The method for polymerizing the latex of the present invention is not particularly limited, and a chloroprene monomer, a carboxyl group-containing vinyl monomer and, if necessary, other copolymerizable ethylenically unsaturated monomer may be used. Radical emulsion polymerization may be performed. Emulsion polymerization may be carried out at a predetermined temperature by emulsifying water, a monomer, an emulsifying / dispersing agent, a polymerization initiator, a chain transfer agent, etc. according to a known method. Each of the raw materials may be added all at once, sequentially or in portions. In particular, a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer is suitable because it has excellent high-temperature adhesiveness and good adhesion to various adherends. Examples of the copolymerizable carboxyl group-containing vinyl monomer include, for example, unsaturated fatty acids such as acrylic acid, methacrylic acid, fumaric acid, maleic acid and crotonic acid, and of these, methacrylic acid is preferred. Chloroprene 10
0.1 to 10 parts by weight of methacrylic acid with respect to 0 parts by weight,
Preferably 0.5 to 4 parts by weight is used. Further, if necessary, as a copolymerizable ethylenically unsaturated monomer, for example, used for the copolymerization of normal chloroprene such as ethylene, methyl methacrylate, acrylonitrile, 2,3-dichlorobutadiene, and 1-chlorobutadiene. The monomer to be used is appropriately used in an amount of 20 parts by weight or less.

The emulsifying / dispersing agent used in the polymerization is not particularly limited, and carboxylic acid type, sulfonic acid type, sulfuric acid ester type anionic emulsifiers, nonionic emulsifiers and the like are used. For example, disproportionated rosin is used. Alkali metal salts of acids, alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulphates, condensates of sodium naphthalene sulfonate and formaldehyde, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenols, sorbitan fatty acid esters, poly Examples thereof include oxyethylene acyl ester. In the case of a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer, alkyldiphenyl ether disulphonic acid alkali metal salt and triethanolamine salt, dodecylbenzene sulfonic acid alkali metal salt and triethanolamine salt , Alkali metal salts of lauryl sulfate, triethanolamine salts and the like are preferably used in emulsion polymerization under acidic conditions.

As the polymerization initiator, known free radical-forming substances, for example, persulfates such as potassium persulfate and ammonium persulfate, inorganic or organic peroxides such as hydrogen peroxide and tert-butyl hydroperoxide, etc. Can be used. In addition, these may be used alone or in a redox system in combination with a reducing substance such as thiosulfate, thiosulfite, and organic amine.

The polymerization temperature is not particularly limited and may be, for example, in the range of 0 to 80 ° C, and 8 to 40 ° C.
Is preferred.

Examples of chain transfer agents include molecular weight regulators such as alkyl mercaptans, halogenated hydrocarbons, alkylxanthogen disulfides and sulfur.

The polymerization terminator is not particularly limited as long as it is a commonly used terminator and, for example, phenothiazine, 2,6-tert-butyl-4-methylphenol, hydroxylamine and the like can be used. The addition may be carried out when a predetermined conversion rate is reached. The polymerization conversion rate is preferably 50 to 100%, and when residual monomers are present, monomer removal may be carried out.

In order to further improve the latex stability of the adhesive latex of the present invention, a method of adding an emulsifying / dispersing agent other than the emulsifying / dispersing agent used in emulsion polymerization is used. When to add an emulsifying / dispersing agent,
There is a method of adding all at the time of charging the polymerization, a method of adding during the polymerization, a method of adding at the end of the polymerization, and the like, but there is no particular limitation. preferable. The addition amount used is 1 to 10 parts by weight, preferably 3 to 5 parts by weight, based on 100 parts by weight of the charged monomers. Within this range, it is possible to satisfy the stability of latex stability and the maintenance of good water resistance when used as an adhesive. As the emulsifying / dispersing agent, an alkali metal salt of rosin acid, a sulfonic acid type, a sulfate ester type anionic emulsifier, a nonion type emulsifier, or the like is used.
For example, alkyl sulfonate having 8 to 20 carbon atoms, alkyl aryl sulfate, condensate of sodium naphthalene sulfonate and formaldehyde, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol, sorbitan fatty acid ester, polyoxyethylene acyl ester. Etc., preferably alkali metal salts and triethanolamine salts of alkyldiphenyl ether disulphonic acid, alkali metal salts and triethanolamine salts of dodecylbenzene sulfonic acid, alkali metal salts of lauryl sulfate and triethanolamine salts, etc. are used. .

The adhesive latex obtained by the present invention can be used alone as an adhesive, but the addition of a tackifier and a metal oxide (hydroxide) will improve the adhesive physical properties.

The tackifier in the present invention is not particularly limited, and examples thereof include a phenol resin, a terpene resin, a rosin derivative resin, and a petroleum hydrocarbon. Examples thereof include hydrogenated rosin and hydrogenated rosin. The pentaerythritol ester, polymerized rosin, rosin-modified resin containing rosin as a main component, alkylphenol resin, rosin-modified phenol resin, terpene-modified phenol resin, natural terpene resin and the like are used.

These resins are contained in an amount of 10 to 60 parts by weight, preferably 20 parts by weight, based on 100 parts by weight of the chloroprene rubber polymer.
~ 40 parts by weight are used. Within this range, sufficient tackiness can be secured and the adhesive performance can be further improved. As an addition method, it may be added by dissolving it in an organic solvent in advance, but it is preferably added in the form of an emulsion dispersed.

The metal oxide (hydroxide) in the present invention is an oxide of a metal cation of Group II to Group III, for example, magnesium oxide (hydroxide), calcium oxide (hydroxide) calcium, and oxide. Examples include (hydroxide) zinc and the like.
These metal oxides (hydroxides) are used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the chloroprene rubber polymer. Within this range, sufficient tackiness can be secured and the adhesive performance can be further improved. As a method of addition, a method of adding in the form of an emulsion dispersed is preferable.

The composition of the latex for heat resistance-improving adhesive and the adhesive composition of the present invention are as described above. It has good adhesive properties and latex stability, and also has excellent heat resistance, especially heat creep resistance.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The latex adhesives obtained in the following Examples and Comparative Examples have room temperature peel strength, high temperature peel strength, heat creep test, water resistance and latex stability (compounding stability, mechanical stability) as follows. It was measured and evaluated by the method.

<Peel strength at room temperature> An SBR rubber plate (150 mm x 25 mm, Showa Rubber) and a No. 9 cotton canvas (150 mm x 25 mm) surface-finished with a No. 60 polishing cloth were coated with the adhesive composition on one side. At about 625 g / m
After applying ² (wet), it was heated and dried at 60 ° C. for 10 minutes, and pressed with a hand roller. A test piece was prepared by curing at 23 ° C. for 3 days in a thermostatic chamber. 2 test pieces
The 180 ° peel strength was measured using a Tensilon type tensile tester under the conditions of 3 ° C. and a pulling speed of 200 mm / min.

<High Temperature Peel Strength> Using a test piece prepared in the same manner as the normal temperature peel strength measurement, 80 ° C. and a pulling speed of 20.
The 180 ° peel strength was measured using a Tensilon type tensile tester under the condition of 0 mm / min.

<Heat resistance creep test> SBR (150 × 25 mm, Showa Rubber) whose surface is finished with No. 60 polishing cloth
After applying 625 g / m ² of the adhesive composition on one side with a brush, it is heated and dried at 60 ° C. for 10 minutes, the shaded portion is covered with a polyethylene sheet as shown in FIG. As shown in (3), the shaded portion was cut off, and compression was performed with a hand roller so that the bonded portion had a size of 25 × 25 mm. A test piece was prepared by curing at 23 ° C. for 3 days in a thermostatic chamber. One end of the test piece was hung in the thermostatic layer so as to perform 180 ° peeling, a 200 g weight was attached to the other end so as not to give an impact, and the temperature in the thermostatic layer was maintained at 80 ° C. The adhesive softened and could not bear the weight load, and the time (minutes) when the weight dropped was measured and used as a heat resistant creep test. The final time is 60 minutes, and when it does not fall, it is indicated by "60 minutes or more". In addition, when it did not fall but was displaced, the length (mm) of the displacement after 60 minutes was measured.

<Water resistance> A test piece prepared in the same manner as the room temperature peel strength measurement was immersed in pure water at 23 ° C. for 3 days, and then excess water was immediately wiped off at 23 ° C. and a pulling speed of 200 m.
The 180 ° peel strength was measured using a Tensilon type tensile tester under the condition of m / min.

<Latex Stability><CompoundingStability> The presence or absence of rubber deposits was observed by compounding the latex for adhesives.

<Mechanical Stability> The mechanical stability of the adhesive composition was measured by measuring the rubber solidification rate using the Marlon test method.

Example 1 Chloroprene, methacrylic acid, having the composition ratios shown in Table 1,
n-dodecyl mercaptan, sodium alkyl diphenyl ether sulfonate (Perex SSH (trademark), manufactured by Kao), condensate of sodium naphthalene sulfonate and formaldehyde (Demol N (trademark), manufactured by Kao), sodium hydrosulfite, triethanolamine And water in a 10 L autoclave with a stirrer 1
Polymerization was performed at 2 ° C. to obtain copolymer latexes A and B.
The properties of the obtained latex are also shown in Table 1.

[0035]

[Table 1]

All polymerizations were carried out in a nitrogen atmosphere at 0.35% by weight.
An aqueous potassium persulfate solution was continuously added dropwise. The conversion was about 98% by weight or more, and 0.05 part by weight of 2,6-tert-butyl-4-methylphenol was added as a polymerization terminator to terminate the polymerization. The resulting copolymer latexes A and B were mixed in a ratio of 15:85, and the tackifier and the metal oxide were blended in the composition ratios shown in Table 2 to obtain an adhesive composition.

[0037]

[Table 2]

Table 3 shows the evaluation results of the room-temperature peel strength, high-temperature peel strength, heat-resistant creep, water resistance, compounding stability, and mechanical stability of the prepared adhesive composition.

[0039]

[Table 3]

From the results shown in Table 3, room temperature peel strength, water resistance,
It was found that the stability was good and the high temperature peel strength and heat creep related to heat resistance were excellent.

Example 2 The physical properties of the adhesive were evaluated according to Example 1 except that the mixing ratio of the copolymer latexes A and B was changed to 30/70. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, the room temperature peel strength, high temperature peel strength, heat resistant creep, water resistance, compounding stability, and mechanical stability were all good results.

Example 3 Chloroprene, methacrylic acid, having the composition ratios shown in Table 1,
n-Dodecyl mercaptan, sodium dodecylbenzene sulfonate, a condensate of sodium naphthalene sulfonate and formaldehyde (Demol N (trademark), manufactured by Kao), sodium hydrosulfite, triethanolamine and water were charged into an autoclave, and Example 1
According to the procedure, copolymer latexes C and D were obtained.

Copolymer latex C and D 30:70
And the physical properties of the adhesive were evaluated according to Example 1. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, the room temperature peel strength, high temperature peel strength, heat resistant creep, water resistance, compounding stability and mechanical stability were all good results.

Example 4 The physical properties of the adhesive were evaluated according to Example 1 except that the mixing ratio of the copolymer latex C and D was changed to 15:85. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, the room temperature peel strength, high temperature peel strength, heat resistant creep, water resistance, compounding stability and mechanical stability were all good results.

Example 5 The physical properties of the adhesive were evaluated according to Example 1 except that the mixing ratio of the copolymer latexes A and B was changed to 70:30. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, water resistance,
The compounding stability, mechanical stability, high-temperature peel strength, and heat-resistant creep were good results, and the room-temperature peel strength showed practically usable values.

Comparative Example 1 Physical properties of the adhesive were evaluated according to Example 1 except that only the copolymer latex B was changed. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results in Table 3, the room temperature peel strength, water resistance, compounding stability and mechanical stability were good, but the high temperature peel strength and heat creep test results related to heat resistance were good. Inferior to that, a drop was observed in 10 minutes.

Comparative Example 2 The physical properties of the adhesive were evaluated according to Example 1 except that only the copolymer latex A was used. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, water resistance,
The compounding stability, mechanical stability, high temperature peel strength and heat resistant crepe gave good results, but the room temperature peel strength was poor and sufficient adhesive properties could not be maintained.

Comparative Example 3 Chloroprene, methacrylic acid, having the composition ratios shown in Table 1,
n-dodecyl mercaptan, sodium alkyl diphenyl ether sulfonate (Perex SSH (trademark), manufactured by Kao), condensate of sodium naphthalene sulfonate and formaldehyde (Demol N (trademark), manufactured by Kao), sodium hydrosulfite, triethanolamine Example 1 with the addition of water and water to the autoclave
According to the procedure, copolymer latexes B and E were obtained.

Copolymer latex B and E 30:70
And the physical properties of the adhesive were evaluated according to Example 1. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results in Table 3, the room-temperature peel strength, water resistance, compounding stability, and mechanical stability were good, but satisfactory results were obtained in heat resistance, especially in heat creep. I couldn't do it.

Comparative Example 4 Chloroprene, methacrylic acid, having the composition ratios shown in Table 1,
n-Dodecyl mercaptan, sodium dodecylbenzene sulfonate, a condensate of sodium naphthalene sulfonate and formaldehyde (Demol N (trademark), manufactured by Kao), sodium hydrosulfite, triethanolamine and water were charged into an autoclave, and Example 1
According to the procedure, copolymer latexes D and F were obtained.

Copolymer latex D and F 70:30
And the physical properties of the adhesive were evaluated according to Example 1. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, water resistance,
Although the compounding stability, mechanical stability and heat-resistant creep were good results, satisfactory results at room temperature peel strength were not obtained due to the presence of solvent-insoluble components.

Comparative Example 5 The physical properties of the adhesive were evaluated according to Example 1 except that the mixing ratio of the copolymer latexes A and C was changed to 50:50. Table 2 shows the composition ratio of the adhesive composition.

As shown in the evaluation results of Table 3, water resistance,
The compounding stability, mechanical stability, high temperature peel strength and heat resistant crepe gave good results, but the room temperature peel strength was poor and sufficient adhesive properties could not be maintained.

[0062]

As described above, the latex for adhesives and the adhesive composition obtained by the present invention have adhesive properties such as room temperature adhesive strength, high temperature adhesive strength, and water resistance which are not found in conventional latex. It is suitable as an adhesive for various applications such as wood, leather, cloth, rubber, plastic, and metal because it has good latex stability and excellent heat resistance, especially heat creep resistance. .

[Brief description of drawings]

FIG. 1 is a styrene-butadiene rubber test piece used in a heat resistance creep test.

FIG. 2 is a styrene-butadiene rubber test piece used in a heat-resistant creep test.

Claims (8)

[Claims] 1. A chloroprene rubber latex in which a 5% chloroform solution is a solution containing no organic solvent insoluble portion and has a solution viscosity of 2000 mPa · s or more, and a solution viscosity of 2
A latex for a heat resistance improving adhesive, which is characterized by comprising a mixture with a chloroprene rubber latex having a viscosity of 000 mPa · s or less. 2. A chloroprene rubber latex in which a 5% chloroform solution is a solution containing no organic solvent insoluble portion and has a solution viscosity of 2000 mPa · s or more, and a solution viscosity of 2
The mixing ratio with the chloroprene rubber latex of 000 mPa · s or less is 50: 5 in the dry weight ratio of the polymer.
The latex for a heat resistance improving adhesive according to claim 1, which is 0 to 1:99. 3. The latex for heat resistance improving adhesive according to claim 1, wherein the chloroprene rubber latex is a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer. 4. The copolymer is a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer obtained by using an emulsifying / dispersing agent imparting latex stability. The latex for a heat resistance improving adhesive according to claim 3. 5. The latex for heat resistance-improving adhesive according to claim 4, wherein the emulsifying / dispersing agent imparting latex stability is a water-soluble salt of alkyldiphenyl ether disulphonic acid. 6. A chloroprene-based adhesive composition comprising the latex for heat resistance-improving adhesive according to any one of claims 1 to 5. 7. 10 to 60 parts by weight of a tackifier and 100 parts by weight of a latex for a heat resistance-improving adhesive according to claim 1, and a metal oxide or a metal hydroxide 1.
A chloroprene-based adhesive composition comprising 5 to 5 parts by weight. 8. The chloroprene-based adhesive composition according to claim 7, wherein the tackifier is selected from a phenolic resin, a terpene resin, a rosin derivative resin or a petroleum hydrocarbon.