JP2001019805A - Chloroprene latex composition, production of same, and adhesive composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition improved in initial tack, water resistance, and ordinary peeling strength by using a chloroprene polymer obtained by polymerizing chloroprene and an ethylenically unsaturated carboxylic acid in the presence of polyvinyl alcohol and having a specified gel content. SOLUTION: Chloroprene or a mixture thereof (100 pts.wt.) with a monomer copolymerizable therewith and 0.5-10 pts.wt. ethylenically unsaturated carboxylic acid are pofymerized at 0-55 deg.C in the presence of 0.5-4 pts.wt. polyvinyl alcohol having a degree of saponification of 60-98 mol% and a degree of polymerization of 200-3,000 to obtain a chloroprene latex composition having a solids concentration of 40-65 wt.%. This composition (100 pts.wt.) is compounded with 5-100 pts.wt. tackifying resin to obtain an adhesive composition. This composition is desirable in bonding e.g. paper, wood, cloth, hides and skins, leather, rubber, plastic, foam, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a chloroprene latex composition effective as an adhesive and a method for producing the same.
The present invention relates to an adhesive composition using the same. More specifically, a chloroprene latex composition which is excellent in balance of initial adhesiveness, water resistance, normal peel strength, etc., and is excellent as an aqueous contact adhesive having excellent adhesiveness such as olefin, a method for producing the same, and an adhesive using the same. Agent composition.

[0002]

2. Description of the Related Art Heretofore, adhesives based on polychloroprene have been mainly of the solvent type. However, in recent years, there has been an increasing demand for solvent-based adhesives to be desolvated due to problems such as toxicity due to organic solvents during production and use, danger of fire, and environmental pollution.

As a technique for removing the solvent, it is considered effective to substitute a solvent type adhesive with a latex adhesive, and latex adhesives using various polymers have been actively studied.

[0004] Above all, the chloroprene latex adhesive is applied to both adherends to be bonded, and after drying these adhesive layers, they are bonded to each other, thereby exhibiting a high adhesive strength immediately after bonding. Because of these characteristics, it is expected to be used as a water-based contact-type adhesive agent, but is inferior in adhesive performance such as initial adhesive strength and water resistance as compared with a solvent-based adhesive agent.

For example, Japanese Patent Publication No. 52-13983 discloses a method for producing a chloroprene latex adhesive in which chloroprene and an α, β unsaturated carboxylic acid are polymerized in the presence of polyvinyl alcohol and a chain transfer agent.
In the examples of this publication, chloroprene and α, β unsaturated carboxylic acid were polymerized in the presence of 5 parts of polyvinyl alcohol by varying the amount of xanthogen disulfide added. The gel fraction was 10%, 60%, A chloroprene polymer that is 70% is indicated. Japanese Patent Application Laid-Open No. 5-222106
Japanese Patent Application Laid-Open Publication No. H11-146,086 discloses a method for producing chloroprene latex in which chloroprene and an α, β unsaturated carboxylic acid are polymerized in the presence of 4.08 parts of polyvinyl alcohol, and the gel content of the chloroprene polymer is about 25%. . But,
The chloroprene latex having such properties was inferior in balance between initial adhesiveness, water resistance, and normal peel strength.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art and provides a chloroprene latex composition for water-based adhesives having an excellent balance of initial adhesive strength, water resistance, normal peel strength and the like. And a method for producing the same, and an adhesive composition using the same.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, chloroprene and an ethylenically unsaturated carboxylic acid have been produced in the presence of a specific amount of polyvinyl alcohol. A chloroprene latex composition obtained by polymerization and having a specific gel content of a chloroprene polymer can provide an adhesive composition having an excellent balance of initial adhesiveness, water resistance, and normal peel strength. The invention has been completed.

That is, the present invention relates to chloroprene or a monomer 10 copolymerizable with chloroprene and chloroprene.
0 parts by weight, and 0.5 to 10 ethylenically unsaturated carboxylic acids.
A chloroprene latex composition obtained by polymerizing parts by weight in the presence of 0.5 to 4 parts by weight of polyvinyl alcohol and having a gel content of a chloroprene polymer of 15 to 50% by weight.

Further, the present invention is the above chloroprene latex composition, wherein the chloroprene polymer has a storage modulus at 20 ° C. of 0.5 to 5 MPa.

Further, the present invention relates to chloroprene or a monomer 10 copolymerizable with chloroprene and chloroprene.
0 parts by weight and 0.5 to 10 parts by weight of ethylenically unsaturated carboxylic acid are polymerized in the presence of 0.5 to 4 parts by weight of polyvinyl alcohol, and the gel content of the obtained chloroprene polymer is 15 to 50 parts by weight. % Of the chloroprene latex composition. Further, the present invention is an adhesive composition containing the above chloroprene latex composition and a tackifier resin.

Hereinafter, the present invention will be described in detail. The present invention
A polymer obtained by polymerizing chloroprene or chloroprene and 100 parts by weight of a monomer copolymerizable with chloroprene, and 0.5 to 10 parts by weight of an ethylenically unsaturated carboxylic acid in the presence of 0.5 to 4 parts by weight of polyvinyl alcohol. And a chloroprene latex composition having a gel content of a chloroprene polymer of 15 to 50% by weight, a method for producing the same, and an adhesive composition using the same.

The chloroprene polymer in the present invention is chloroprene (indicating 2-chloro-1,3-butadiene).
And a copolymer of ethylenically unsaturated carboxylic acid and chloroprene and one or more copolymerizable monomers.

Specific examples of the ethylenically unsaturated carboxylic acid in the present invention include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, citraconic acid, glutaconic acid and the like. More than one kind can be used in combination. Among them, the use of acrylic acid and methacrylic acid is preferred.

The amount of addition of the ethylenically unsaturated carboxylic acid is
The amount is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, more preferably 2 to 4 parts by weight, per 100 parts by weight of chloroprene or chloroprene and a monomer copolymerizable with chloroprene. When the amount of the ethylenically unsaturated carboxylic acid is less than 0.5 part by weight, the adhesive strength and heat resistance are reduced, and the stability of the latex is also reduced. Also one
If it exceeds 0 parts by weight, the storage stability of the latex will be poor.

The monomers copolymerizable with chloroprene in the present invention include, for example, 2,3-dichloro-1,3-butadiene and 1-chloro-1,3-butadiene other than the above ethylenically unsaturated carboxylic acids. Butadiene, butadiene, isoprene, styrene, acrylonitrile, esters of acrylic acid, esters of methacrylic acid, and the like,
If necessary, two or more kinds may be used. These monomers are used in the range of 0 to 50% by weight based on chloroprene.

The type of polyvinyl alcohol in the present invention is not particularly limited, but has a saponification degree of 60-9.
Those having 8 mol% and a degree of polymerization in the range of 200 to 3000 are preferred. More preferably, the saponification degree is 75 to 95 mol%,
The polymerization degree is 200 to 700, and the polymerization operation can be performed stably, and the obtained latex has excellent stability.

In the present invention, the added amount of polyvinyl alcohol must be 0.5 to 4 parts by weight. It is more preferably 2 to 4 parts by weight, and still more preferably 3.0 to 3.5 parts by weight.
Parts by weight. The amount of polyvinyl alcohol added is 0.5
When the amount is less than part by weight, the emulsifying power is not sufficient, the polymerization reaction becomes extremely slow, and a stable latex cannot be obtained. If the amount exceeds 4 parts by weight, the viscosity of the polymerization reaction and the product becomes high, which is disadvantageous in high solidification and lowers the water resistance as an adhesive.

The chloroprene polymer used in the present invention has a gel content of toluene-insoluble in the range of 15 to 50% by weight, preferably 20 to 45% by weight, more preferably 30 to 40% by weight. . Gel content is 15
When the amount is less than the weight%, the initial adhesive strength and the normal adhesive strength are reduced, and the heat resistance and the shear strength are significantly reduced. If the gel content exceeds 50% by weight, the initial adhesiveness is reduced and the water resistance is significantly reduced.

The gel content of the chloroprene polymer can be controlled by controlling the use of the chain transfer agent, the amount thereof used, the polymerization temperature and the polymerization rate.

First, the chain transfer agent is not particularly limited as long as it is generally used for producing a chloroprene polymer. For example, n-dodecyl mercaptan or tert-
Known chain transfer agents such as long chain alkyl mercaptans such as dodecyl mercaptan, dialkyl xanthogen disulfides such as diisopropylxanthogen disulfide and diethylxanthogen disulfide, and iodoform can be used. In particular, in order to control the gel content efficiently and stably, it is preferable to use octyl mercaptan.

Next, the polymerization temperature is preferably in the range of 0 to 55 ° C. from the viewpoint of polymerization control. In order to carry out the polymerization reaction more smoothly and safely, the polymerization temperature should be 30 to 50 ° C.
It is preferable that

The final polymerization rate is preferably at least 80% by weight, more preferably at least 90% by weight.

The chloroprene polymer of the present invention has a storage modulus at 20 ° C. of preferably 0.5 to 5 MPa, more preferably 0.7 to 3 MPa. This storage elastic modulus can be measured by preparing a polymer film or sheet from a latex sample and using a viscoelasticity measuring device. If the storage elastic modulus is less than 0.5 MPa, the initial adhesive strength and the normal adhesive strength are reduced, and the heat resistance and the shear strength are significantly reduced. On the other hand, when the storage modulus exceeds 5 MPa, the initial adhesion and the water resistance decrease.

In the present invention, the solid content of the chloroprene latex is preferably in the range of 40 to 65% by weight, more preferably 50 to 60% by weight. A higher solids concentration results in a latex with a faster drying rate and better initial adhesion. The solid content can be adjusted by the ratio of the monomer and water at the time of polymerization, but can be adjusted by concentration after polymerization.

The chloroprene latex composition obtained in the present invention can be added with a basic substance such as diethanolamine or triethanolamine as a pH adjuster, a surfactant such as aliphatic alkanolamide, a rosin acid ester resin, Terpene phenolic resin, coumarone-
Tackifying resins such as indene resins, aliphatic hydrocarbon resins, and aromatic resins; metal oxides such as zinc oxide; inorganic fillers such as calcium carbonate and silica; plasticizers and softeners such as dibutyl phthalate and process oil; An antioxidant and the like can be optionally added. In particular, it is preferable to use a tackifier resin for the purpose of controlling the adhesive performance,
In particular, it is preferable to add a terpene phenol-based or rosin-ester-based resin emulsion or a water-soluble coumarone indene resin, and it is particularly convenient to add an emulsified resin.

The amount of the additives contained in the adhesive composition of the present invention is preferably 5 to 100 parts by weight of the tackifier resin and 0 to 50 parts by weight of the other components based on 100 parts by weight of chloroprene latex. . Further, the solid content concentration in the adhesive composition is preferably in the range of 40 to 70% by weight, more preferably in the range of 50 to 70% by weight.

The chloroprene latex adhesive obtained according to the present invention is suitable for bonding the same or different kinds of paper, wood, cloth, leather, leather, rubber, plastic, foam, pottery, glass, ceramic, metal and the like. It is. In particular, when an olefin-based plastic or rubber is used as the adherend, higher adhesive performance is exhibited as compared with the prior art. Regarding the application method at the time of bonding, brush application, iron application, spray application, roll coater application and the like are possible.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention. In the following description, parts and percentages are shown on a weight basis.

Example 1 In a reactor having an internal volume of 3 liters, 94 parts of water and 3.5 parts of polyvinyl alcohol (denkapovar B-05, saponification degree: 88 mol%, polymerization degree: 550) under a nitrogen stream were 3.5. The mixture was heated (60 ° C.) and dissolved. After the aqueous solution was cooled to near room temperature, 97 parts of a chloroprene monomer, 3 parts of methacrylic acid, and 0.4 part of octyl mercaptan were added thereto. While maintaining this at 45 ° C., polymerization was carried out using sodium sulfite and potassium persulfate as initiators to obtain a latex. Final polymerization rate is 9
8%.

Next, the chloroprene latex was added to
After adjusting the pH to 7 by adding a 0% aqueous solution of diethanolamine, 3 parts of a 20% aqueous solution of 1: 2 mol type fatty acid alkanolamide (manufactured by Diamond Shimalok Chemical Co., Ltd.) was added. Further, the water was evaporated under reduced pressure and concentrated to adjust the solid content concentration to 55%.

Next, the following measurement was performed on the chloroprene latex. [Measurement of Gel Content (Gel Content)] A latex sample was freeze-dried and precisely weighed to obtain A. The gel was dissolved in toluene (adjusted to 0.6%), and the gel was separated using a centrifuge and a 200-mesh wire net. The gel component was air-dried and then dried for 1 hour in a 110 ° C. atmosphere. The gel content was calculated according to the following equation. Gel content = B / A × 100 (%) The results are shown in Table 1.

[Storage modulus] A latex sample was applied to a glass plate and dried at room temperature for one week to obtain a sheet having a thickness of about 1 mm. A test piece having a width of 4 mm and a length of 38 mm was punched out of this sheet, and a viscoelasticity measuring device Leo Vibron DD was used.
The measurement was performed using V-25F (manufactured by Orientec) at 20 ° C., an amplitude of ± 1%, a preload of 30 g, and a frequency of 1 Hz.

[Initial peel strength] An adhesive composition was prepared according to the formulation shown in Table 1. Next, canvas (25 x 150 mm) 2
A 300 g (solid content) / m ² adhesive composition was applied to each sheet with a brush, dried under an atmosphere of 80 ° C. for 9 minutes, and dried at room temperature for 1 minute.
After standing for a minute, the coated surfaces were stuck together and pressed with a hand roller. Ten minutes after pressing, using a tensile tester, pulling speed 2
The 180 ° peel strength was measured at 00 mm / min.

[Normal Peeling Strength] An adhesive composition was prepared according to the formulation shown in Table 1. Next, canvas (25 x 150 mm) 2
A 300 g (solid content) / m ² adhesive composition was applied to each sheet with a brush, dried under an atmosphere of 80 ° C. for 9 minutes, and dried at room temperature for 1 minute.
After standing for a minute, the coated surfaces were stuck together and pressed with a hand roller. 7 days after pressing, using a tensile tester, a tensile speed of 20
The 180 ° peel strength was measured at 0 mm / min.

[Water Resistance] An adhesive composition was prepared according to the formulation shown in Table 1. Next, 300 g (solid content) / m ² of the adhesive composition was applied to each of two canvases (25 × 150 mm) with a brush, dried in an atmosphere of 80 ° C. for 9 minutes, left at room temperature for 1 minute, and then coated. It was pressed with a hand roller.
Seven days after the pressing, it was immersed in water for 2 days, and the 180 ° peel strength was measured at a pulling speed of 200 mm / min using a tensile tester.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that 0.45 parts of octyl mercaptan was used. The gel content and the adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Example 3 Polymerization was carried out in the same manner as in Example 1 except that 0.50 parts of octyl mercaptan was used. The gel content and the adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that 0.25 parts of octyl mercaptan was used. The gel content and the adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that 0.60 part of octyl mercaptan was used. The gel content and the adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1 except that 4.5 parts of polyvinyl alcohol was used. The gel content and adhesive properties were measured as in Example 1,
The results are shown in Table 1.

[0041]

[Table 1]

[0042]

From the comparison between the above Examples and Comparative Examples, it is clear that the chloroprene latex composition of the present invention is excellent in the balance of initial adhesive strength, water resistance, and normal adhesive strength. A chloroprene latex composition particularly suitable for bonding paper materials, synthetic resins, steel plates, and the like, a method for producing the same, and an adhesive composition can be provided.

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Claims (4)

[Claims] A chloroprene or chloroprene and 100 parts by weight of a monomer copolymerizable with chloroprene, 0.5 to 10 parts by weight of an ethylenically unsaturated carboxylic acid, and 0.5 to 4 parts by weight of polyvinyl alcohol A chloroprene latex composition comprising a chloroprene polymer having a gel content of 15 to 50% by weight. 2. The chloroprene latex composition according to claim 1, wherein the chloroprene polymer has a storage modulus at 20 ° C. of 0.5 to 5 MPa. 3. Chloroprene or chloroprene and 100 parts by weight of a monomer copolymerizable with chloroprene and 0.5 to 10 parts by weight of an ethylenically unsaturated carboxylic acid are added in the presence of 0.5 to 4 parts by weight of polyvinyl alcohol. A method for producing a chloroprene latex composition, wherein the gel content of the chloroprene polymer obtained by polymerization is 15 to 50% by weight. 4. An adhesive composition comprising the chloroprene latex composition according to claim 1 and a tackifier resin.