CN1763143A - Method for prolonging the effective time of polychloroprene-based two-component water-based adhesive - Google Patents

Abstract

Two-part water-based adhesives of the prior art wherein isocyanates were used in order to improve the bond strength and the workability often exhibited such short pot lives as to become a problem in practical use. According to the invention, the pot life of a two-part water-based polychloroprene adhesive comprising a polychloroprene latex as the chief material and a polyisocyanate compound as the curing agent can be prolonged to a practically unproblematic level by adding an alkyl diphenyl ether disulfonic acid salt and/or a polyoxyethylene alkyl ether sulfate salt to the adhesive.

Description

Method for prolonging the effective time of polychloroprene-based two-component water-based adhesive

This application is an international application number PCT/JP02/11947, the international application date is November 15, 2002. After the PCT international application entered the Chinese phase, the national application number is 02822784.0 and the title is "Polychloroprene-based 2-component water system A divisional application of the Chinese patent application "Method for Prolonging Effective Time of Adhesive".

technical field

The present invention relates to a method for improving the effective time of a two-component water-based adhesive with polychloroprene latex as the main agent and polyisocyanate as the curing agent after the isocyanate is mixed.

Background technique

In many fields where conventional solvent-based adhesives are used, it is desired to switch to water-based adhesives in view of the safety and hygiene of operators and the work environment. However, water-based adhesives are inferior to solvent-based adhesives in terms of adhesive strength and workability.

In order to improve these aspects, a 2-component water-based adhesive using isocyanate in combination has been proposed, but currently, due to the formulation, the 2-component adhesive often has a practical problem of short pot life.

disclosure of invention

In view of the current situation, the present invention aims to provide a method capable of controlling the effective time of a polychloroprene-based two-component water-based adhesive.

The inventors of the present invention have conducted serious studies to achieve the above object and found that by adding a specific surfactant to a two-component adhesive having polychloroprene latex as the main ingredient and polyisocyanate as the curing agent, the The effective time of the water-based adhesive was extended to a practical level, and the present invention was completed.

That is, the present invention is a method for prolonging the pot life of a two-component adhesive, and the method is characterized in that in a two-component adhesive using polychloroprene latex as a main ingredient and a polyisocyanate compound as a curing agent, Add alkyl diphenyl ether disulfonate and/or polyoxyethylene alkyl ether sulfate.

The best way to practice the invention

Hereinafter, the content of the present invention will be described in detail. The polychloroprene of the present invention refers to the homopolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene), or chloroprene and can be copolymerized with chloroprene monomeric copolymers. The copolymer also includes a graft copolymer formed by graft-polymerizing other monomers in the presence of polychloroprene.

Preferred monomers that can be copolymerized with chloroprene include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene Diene, styrene, acrylonitrile, acrylic acid or its esters, methacrylic acid or its esters, and the like may be used in combination of two or more as necessary.

The polymerization method for obtaining polychloroprene is not particularly limited, and the method of emulsion polymerization is generally adopted, which is very simple. If the method of emulsion polymerization is adopted, the polychloroprene latex obtained can be directly used in the present invention.

In the present invention, when polychloroprene is obtained by methods other than emulsion polymerization, after dissolving the obtained polychloroprene in an organic solvent, the solution is dispersed in an emulsion, and then the organic solvent is removed, In this way, polychloroprene latex can also be obtained, but the process is increased and the cost will also increase.

The emulsifier and/or dispersant used for the emulsion polymerization of polychloroprene latex is not particularly limited, and various anionic and/or nonionic emulsifiers generally used for chloroprene latex can be used.

As anionic emulsifiers, include carboxylic acid type, sulfonic acid type, sulfate ester type, etc. Condensate of sodium naphthalenesulfonate and formaldehyde, etc. Specific examples of the nonionic type include polyvinyl alcohol or a copolymer thereof (for example, a copolymer with acrylamide), polyvinyl ether or a copolymer thereof (for example, a copolymer with maleic acid), polyvinylpyrrolidone or Copolymers thereof (for example, copolymers with vinyl acetate), modified products of these polymers (copolymers), etc., or cellulose-based derivatives (hydroxyethyl cellulose) and the like. Among them, the above-mentioned citronellic acid salts are particularly suitable for the present invention.

The amount of the emulsifier and/or dispersant added to the polychloroprene-based latex of the present invention corresponds to 100 parts by mass of the initially charged chloroprene monomer (in the case of a chloroprene homopolymer), or It is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the total amount of the chloroprene monomer and comonomer charged first (in the case of a chloroprene copolymer). When it is less than 0.5 parts by mass, the emulsifying ability is insufficient, and when it exceeds 20 parts by mass, there is a disadvantage that the water-resistant adhesive force decreases.

The polymerization temperature for obtaining the polychloroprene-based latex of the present invention is not particularly limited, but the polymerization temperature is preferably 0 to 50° C. for smooth progress of the polymerization reaction. As the polymerization initiator, persulfates such as potassium persulfate and organic peroxides such as t-butyl hydroperoxide can be used, but are not particularly limited.

The type of chain transfer agent used for polymerization to obtain polychloroprene is not particularly limited, and reagents generally used for emulsion polymerization of chloroprene can be used. For example, long-chain alkyl mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, disulfide disulfides such as diisopropyl xanthate disulfide and diethyl xanthate disulfide can be used. Known chain transfer agents such as alkyl xanthates and iodoform. The type of polymerization inhibitor (polymerization inhibitor) of polychloroprene is not particularly limited, and for example, 2,6-di-tert-butyl-4-methylphenol, phenothiazine, hydroxylamine and the like can be used.

The final polymerization rate of polychloroprene is not particularly limited and can be adjusted arbitrarily. Unreacted monomers can be removed by a monomer removal operation, but the method is not particularly limited.

By concentrating or diluting the polychloroprene-based latex of the present invention by adding water or the like, the concentration of solid components can be controlled to a necessary concentration. Concentration under reduced pressure and the like can be used as the concentration method, but it is not particularly limited.

The properties of the polychloroprene-based latex of the present invention are not particularly limited, and can be controlled by appropriately selecting and controlling polymerization temperature, polymerization initiator, chain transfer agent, polymerization inhibitor, final polymerization rate, monomer removal and concentration conditions, etc. The solid content concentration, the molecular weight of the toluene-soluble part, the toluene-insoluble content (gel content), etc. were adjusted.

The gel content of the chloroprene (co)polymer in the polychloroprene-based latex is preferably adjusted to 3 to 60% by mass in view of the balance between the initial adhesive force and the normal adhesive force.

The alkyl diphenyl ether disulfonate used in the present invention is represented by the following chemical formula 1. In the formula, R represents an alkyl group having preferably 6 to 20 carbon atoms, and B preferably represents alkali metal ions such as potassium and sodium, ammonium ions, and the like. Preferable examples thereof include disodium or dipotassium dodecyl diphenyl ether sulfonate, disodium or dipotassium octadecyl diphenyl ether sulfonate, but are not particularly limited.

chemical formula 1

The polyoxyalkylene alkyl ether sulfate used in the present invention is represented by Chemical Formula 2 below. In the formula, R1 represents an alkyl group having preferably 6 to 20 carbon atoms, particularly preferably 10 to 16 carbon atoms. R2 represents an alkylene group having preferably 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms. B represents alkali metal ions such as sodium and potassium, ammonium ions, and the like. Preferable examples include sodium or potassium polyoxyethylene lauryl ether sulfate, sodium or potassium polyoxyethylene stearyl ether sulfate, but are not particularly limited.

R1-(O-R2-) _n -SO ₄ ·B chemical formula 2

The addition amount of alkyl diphenyl ether disulfonate and/or polyoxyethylene alkyl ether sulfate is not particularly limited, but it is preferably 5 parts by mass or less per 100 parts by mass of polychloroprene. If the added amount is more than 5 parts by mass, it may adversely affect adhesive properties. More preferably, the added amount is 0.01 to 2 parts by mass based on 100 parts by mass of polychloroprene.

The method of adding the alkyl diphenyl ether disulfonate and/or the polyoxyethylene alkyl ether sulfate is not particularly limited, and a relatively simple method is a method of directly adding or adding as an aqueous solution. The addition time of alkyl diphenyl ether disulfonate and/or polyoxyethylene alkyl ether sulfate is not particularly limited, as long as it is added before adding polyisocyanate, but it must be uniformly dispersed before adding polyisocyanate .

In addition, the effect of prolonging the effective time is first shown by adding a surfactant with the specific structure shown in the present invention, and not any kind of surfactant can show this effect.

The polyisocyanate compound of this invention is a compound which has 2 or more isocyanate groups in a molecule|numerator. Examples include toluene diisocyanate (TDI), xylylene diisocyanate (XDI), 1,3-bis(isocyanatomethyl)cyclohexane, 1,6-hexamethylene diisocyanate (HDI), norbornanol Nene diisocyanate (NBDI), tetramethylxylylene diisocyanate, isophorone diisocyanate (IPDI), 4,4'-diphenylmethane diisocyanate (MDI), trimethylhexamethylene Diisocyanate (TMDI), p-phenylene diisocyanate (PPDI), lysine diisocyanate (LDI), naphthalene diisocyanate (NDI), cyclohexyl diisocyanate (CHDI), triphenylmethane-4,4′,4″ - Triisocyanate, tris(p-phenylisocyanate) phosphorothioate, etc.

In addition, the so-called blocked isocyanate in which the isocyanate group of these polyisocyanate compounds is masked by a blocking agent, and the polyurethane prepolymer derived from these polyisocyanate compounds, when containing two or more isocyanates, are also included in the scope of the present invention. of polyisocyanate compounds.

In terms of dispersibility, it is generally preferable to use a soap-free water-dispersible polyisocyanate having a water-dispersible structure obtained by imparting a nonionic hydrophilic group to a polyisocyanate compound among water-based adhesives.

In addition to the essential components, the polychloroprene-based two-component adhesive of the present invention may optionally add adhesive-imparting resins, tackifiers, metal oxides, fillers, film-forming aids, UV absorbers, antioxidants, plasticizers, vulcanizing agents, vulcanization accelerators, defoamers, etc. By adding these additives, properties such as initial adhesion, water-resistant adhesion, and adhesion retention time can be more practically balanced.

When the adhesive-imparting resin is blended into the water-based adhesive, the type is not particularly limited. Specific examples include rosin resins, polymerized rosin resins, α-pinene resins, β-pinene resins, terpene phenol resins, _C5 fraction petroleum resins, _C9 fraction petroleum resins, and _C5 / _C9 fraction petroleum resins. resin, DCPD-based petroleum resin, alkylphenol resin, xylene resin, coumarone resin, coumarone-indene resin, etc. In order to obtain sufficient initial adhesive strength, a resin having a softening point temperature of 50 to 160°C is preferred.

The method of adding the adhesive-imparting resin is not particularly limited, but it is preferably added as an aqueous emulsion in order to uniformly disperse the resin.

The method of preparing the aqueous emulsion of the adhesive-imparting resin includes the method of emulsifying/dispersing the solution formed by dissolving the resin in an organic solvent such as toluene with an emulsifier, and removing the organic solvent by heating while reducing pressure, and pulverizing The method of emulsifying/dispersing fine particles, etc., is more preferable because the former method can produce an emulsion with smaller particles.

By mixing a thickener into the polychloroprene-based latex composition of the present invention, its viscosity can be adjusted arbitrarily. Specific thickeners include polyvinyl alcohol (PVA), sodium polyacrylate, water-soluble polyurethane, associative polyurethane emulsion, alkali-swellable acrylic emulsion, carboxymethylcellulose (CMC) , methylcellulose (MC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), polyvinyl alcohol and synthetic montmorillonite, etc.

The compounding amount of the tackifier is based on solid content, corresponding to 100 mass parts of polychloroprene latex, is 0.01-10 mass parts (converted to solid content), preferably 0.01-2 mass parts. The viscosity of the polychloroprene-based latex composition can be adjusted without adversely affecting the adhesive properties by mixing the tackifier within this range.

The scope of application of the method for extending the pot life of the polychloroprene-based two-component water-based adhesive of the present invention is not particularly limited, and it can be used in all applications requiring high adhesive strength. Specifically, it includes various uses in the shoe industry, furniture and woodworking fields, clothing processing, roofing materials, automobiles, and construction.

Example

The effects of the present invention will be described in detail below through examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, unless otherwise specified, parts and % represent mass standards.

[Synthesis Example 1]

With a reactor with an inner volume of 3 liters, 100 parts of water, 5 parts of disproportionated citronellic acid, 0.6 parts of sodium hydroxide, 0.7 parts of potassium hydroxide, 0.3 parts of sodium salt of formaldehyde-naphthalenesulfonic acid condensate, 0.3 parts of Parts of sodium bisulfite and dissolved, while stirring, add 100 parts of chloroprene monomer and 0.14 parts of n-dodecyl mercaptan. Potassium persulfate was used as an initiator, polymerization was carried out at 10° C. in a nitrogen atmosphere, and after the polymerization rate reached 90%, an emulsion of phenothiazine was added to stop the polymerization. Unreacted monomers were removed under reduced pressure to obtain polychloroprene latex. Then, water was evaporated and concentrated under reduced pressure to adjust the solid content to 50% by mass.

[Example 1]

Using the polychloroprene latex obtained in Synthesis Example 1, according to the ratio shown in Table 1, in the polychloroprene latex, the emulsion of the resin that imparts adhesiveness, the zinc oxide emulsion, and dodecane are mixed. disodium diphenyl ether sulfonate and stir. Then, a tackifier is added to adjust the viscosity to a range of 1000 to 1500 mPa·s to form the main ingredient of the water-based adhesive.

According to the ratio shown in Table 1, a polyisocyanate compound was added to this main ingredient and stirred to prepare a two-component water-based adhesive.

The mixing ratio shown here is the number of parts in terms of solid content of each mixing component corresponding to 100 parts of polychloroprene in the whole chloroprene latex.

The following pot life and adhesion tests were performed on the adhesive prepared in Example 1.

In addition, the samples used for the adhesion test were prepared in the following order.

On the surface of the canvas (#9), the above-prepared adhesive was applied with a brush at a ratio of 300 g/m ² (in terms of solid content). After standing for 20 minutes, two pieces of canvas cut out from the obtained canvas were bonded together with the adhesive faces facing each other, and pressed together with a hand roller. Adhesion test was carried out after curing for 5 days.

[effective time test]

Immediately after adding the polyisocyanate, the appearance observation (presence or absence of coagulation) and viscosity measurement were carried out. There are 3 levels of evaluation. Compared with before the addition of polyisocyanate, it is judged as normal (O), the viscosity has increased slightly but the usable level is judged to be within the usable range (△), there is coagulation or the viscosity increases greatly, and it is difficult to use The status is judged as unusable (×).

[Normal Adhesion Evaluation Test]

For the samples cured for 5 days, the T-peel strength was measured with a tensile testing machine at room temperature at a tensile speed of 200 mm/min.

[Heat-resistant adhesive force evaluation test]

For the samples cured for 5 days, the T-peel strength was measured with a tensile testing machine in an atmosphere of 80°C at a tensile speed of 200mm/min.

[Water-resistant adhesive force evaluation test]

At room temperature, the samples cured for 5 days were immersed in pure water for 2 days. After 2 days, gently wipe off the moisture on the sample taken out, and immediately use a tensile testing machine to measure the T-peel strength at room temperature at a tensile speed of 200mm/min.

[Example 2 and Comparative Examples 1 to 5]

Except for using the adhesive formulation described in Table 1, the same operation was performed as in Example 1, and the adhesion test results of the obtained samples are shown in Table 1.

Table 1 Example comparative example 1 2 1 2 3 4 5 Adhesive formulation [parts] CR latex 100 100 100 100 100 100 100 Resin Emulsion (1) 50 50 50 50 50 50 50 Zinc Oxide Emulsion (2) 1 1 1 1 1 1 1 Pelex SS-H(3) 0.4 - - - - - - Emal D-3-D(4) - 0.4 - - - - - Emal 10(5) - - - 0.4 - - - Neopelex No.25(6) - - - - 0.4 - - Pelex CS(7) - - - - - 0.4 - Emulgen E-220(8) - - - - - - 0.4 Tackifier A-20L(9) Appropriate amount Appropriate amount Appropriate amount Appropriate amount Appropriate amount Appropriate amount Appropriate amount Takenate WD-730(10) 4 4 4 4 4 4 4 Effective time test (11) 1 hour later ○ ○ ○ △ ○ ○ ○ 3 hours later ○ ○ △ x ○ ○ ○ 6 hours later ○ ○ x x x △ x 24 hours later △ △ x x x x x Adhesion [N/mm] normal adhesion 5.0 4.5 4.2 4.3 4.6 4.4 4.3 heat resistant adhesion 2.2 2.1 2.2 2.1 2.1 1.9 1.9 Water-resistant Adhesion 3.0 2.8 2.7 2.7 2.6 2.6 1.9

(1) Tamanol E-100 (solid content 53%)/manufactured by Arakawa Chemical Industry Co., Ltd.

(2) AZ-SW (solid content 50%)/manufactured by Ohsaki Kogyo Co., Ltd.

(3) Disodium alkyl diphenyl ether sulfonate/manufactured by Kao Corporation

(4) Sodium polyoxyethylene alkyl (C10-16) ether sulfate/manufactured by Kao Corporation

(5) Sodium lauryl sulfate/manufactured by Kao Corporation

(6) Sodium dodecylbenzenesulfonate/manufactured by Kao Corporation

(7) Sodium dioctyl sulfosuccinate/manufactured by Kao Corporation

(8) Polyoxyethylene cetyl ether/manufactured by Kao Corporation

(9) Aron A-20L/Toagosei Co., Ltd.

(10) Water-dispersed polyisocyanate/manufactured by Mitsui Takeda Chemical Co., Ltd.

(11) Effective time test evaluation: ○ indicates a slight change, △: the viscosity has increased, but can be used, ×: can not be used

Possibility of industrial use

In the two-component adhesive of the present invention, which uses polychloroprene latex as the main agent and polyisocyanate compound as the curing agent, by adding alkyl diphenyl ether disulfonate and/or polyoxyethylene alkane Ether sulfate does not adversely affect the adhesive properties and prolongs the effective time of polychloroprene-based two-component adhesives.

Claims (5)

1. the prolongation method of working lipe is characterized in that, is being host with the polychloroprene latex, is being to add polyoxyethylene alkyl ether sulfate salt in the 2 liquid type aqueous adhesives of solidifying agent with the polyisocyanate compounds.

2. the method for claim 1, its feature is that also corresponding to the polychloroprene latex (being scaled solid formation branch) of 100 mass parts, the addition of polyoxyethylene alkyl ether sulfate salt is below 5 mass parts.

3. method as claimed in claim 1 or 2, its feature also are, before the mixing polyisocyanate compounds, add polyoxyethylene alkyl ether sulfate salt in polychloroprene latex in polychloroprene latex.

4. the prolongation method of working lipe as claimed in claim 1 or 2, its feature also be, polyoxyethylene alkyl ether sulfate salt such as following Chemical formula 2 represent,

R1-(O-R2-) _n-SO ₄The B Chemical formula 2

In the formula, R1 represents alkyl, and R2 represents alkylidene group, and B represents alkalimetal ion, ammonium ion etc.

5. the prolongation method of working lipe as claimed in claim 1 or 2, its feature is that also polychloroprene latex is by the emulsification of lemongrass phosphate-gallate series emulsifying agent.