JPS6318634B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel contact adhesive compositions. More specifically, the present invention relates to an aqueous contact adhesive composition prepared by adding an isocyanate compound to an aqueous dispersion of an ethylene-vinyl ester copolymer having a specific copolymer composition. Conventionally, when bonding rubber, metal, plastic, etc., after applying an adhesive to the adherend, it exhibits strong adhesive force when it is dried and then pressed together, and the strength increases over time. These types of contact adhesives are widely used, and a typical example is a solvent-based chloroprene adhesive. However, in recent years, the use of organic solvents has been restricted from the viewpoint of safety and health, air pollution, fire risk, and resource conservation, and a shift is being made to aqueous systems. In response to these trends, some water-based contact adhesives have recently come on the market, but not only have they not yet achieved sufficient contact properties compared to solvent-based chloroprene adhesives, but The reality is that adhesive performance is poor, particularly in terms of water resistance, and satisfactory performance is not always achieved. For example, with acrylic water-based contact adhesives, if the adhesive is completely dried after application, the adhesive strength under normal conditions may not be sufficient, and even if the adhesive strength under normal conditions is relatively high, after immersion in water. There are drawbacks such as low water resistant adhesive strength. In addition, chloroprene-based water-based contact adhesives are known, but they do not have sufficient contact properties or water resistance, and even those based on styrene-butadiene copolymer latex (SBR) have similar problems. In addition to having drawbacks, it also has poor aging resistance. In view of the current situation, the present inventors have conducted intensive research to obtain a water-based contact adhesive composition with excellent contact properties, adhesive properties, and aging resistance. Contains a specific ethylene-vinyl ester copolymer resin aqueous dispersion having properties, that is, polyvinyl alcohol (hereinafter abbreviated as PVA), and contains ethylene 5-50
Aqueous copolymer of ethylene and vinyl ester, consisting of 50-95% by weight of vinyl ester of higher carboxylic acid having 5 to 12 carbon atoms and 45-0% by weight of vinyl ester of lower carboxylic acid having 2 to 4 carbon atoms. The present invention was completed based on the discovery that a composition obtained by adding an isocyanate compound to a dispersion liquid exhibits excellent contact and adhesive properties. Incidentally, among the components of the aqueous contact adhesive composition of the present invention described above, ethylene, a copolymer of a vinyl ester of a higher carboxylic acid and a vinyl ester of a lower carboxylic acid are known as pressure-sensitive adhesive components. The copolymer alone cannot be used as a contact adhesive because it has poor permanent adhesive strength and high-temperature adhesive strength, which are essential for a contact adhesive.
The above problems were solved by creating a specific system that also contained PVA and an isocyanate compound, and its usefulness as a contact adhesive was discovered for the first time. Examples of vinyl esters of higher carboxylic acids having 5 to 12 carbon atoms used in the present invention include vinyl pivalonate, vinyl laurate, vinyl stearate, and vinyl esters of tertiary carboxylic acids having an average carbon number of 10. , preferably a vinyl ester of a tertiary carboxylic acid with an average carbon number of 10 (Veova
-10, manufactured by Ciel Chemical Co., Ltd.), and these higher carboxylic acid vinyl esters are not limited to one type, but two or more types may be used. Vinyl esters of lower carboxylic acids having 2 to 4 carbon atoms include vinyl acetate, vinyl propionate, etc. Vinyl acetate is preferably used, but of course these lower carboxylic acid vinyl esters are not limited to just one type. Two or more types may be used. The aqueous resin dispersion used in the present invention is
This is an aqueous copolymer dispersion consisting of ethylene, a vinyl ester of a higher carboxylic acid having 5 to 12 carbon atoms, and a vinyl ester of a lower carboxylic acid having 2 to 4 carbon atoms. 5~
50% by weight, higher carboxylic acid vinyl ester is 50~
95% by weight, lower carboxylic acid vinyl ester 45~
It is 0% by weight. Adhesive compositions using copolymer aqueous dispersions containing amounts other than the above-mentioned amounts cannot satisfy the good contact properties and adhesive properties that are the characteristics of the present invention. For example, when the amount of ethylene is 5. If the amount of higher carboxylic acid vinyl ester is less than 50% by weight
If the amount is less than 45% by weight, the contact property will be poor due to the large cohesive force, and if the amount is more than 45% by weight, not only will the contact property be poor, but the water resistance will also be reduced. Also, the amount of ethylene is 50
Not only is it difficult to produce at a relatively low pressure when the amount is greater than 1% by weight, but even when a PVA isocyanate compound is used in combination, the cohesive force is insufficient and the high-temperature adhesive strength is poor, making it unsuitable as a contact adhesive. If desired, the ethylene-vinyl ester copolymer used in the present invention may be used in combination with other copolymerizable vinyl monomers in an amount that does not adversely affect performance. Examples of vinyl monomers used in this case include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, crotonic acid, and itaconic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-acrylic acid. Ethylhexyl, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2
- Acrylic acids such as ethylhexyl, and alkyl methacrylates, N-vinylpyrrolidone, acrylonitrile, acrylamide, 2-hydroxyethyl methacrylate, N-methylol acrylamide, glycidyl methacrylate, vinyl chloride, vinylidene chloride, diallyl phthalate, triallyl cyanurate, Examples include ethylene glycol dimethacrylate and divinylbenzene. The aqueous copolymer resin dispersion containing PVA used in the present invention is obtained by emulsion copolymerization of vinyl esters consisting of the above-mentioned higher carboxylic acid vinyl esters and lower carboxylic acid vinyl esters and ethylene using PVA as a protective colloid. As an aqueous resin dispersion, a PVA aqueous solution added later, or a protective colloid.
It can be obtained by post-adding an aqueous PVA solution to the above aqueous dispersion of ethylene-vinyl ester copolymer without using PVA. The PVA used in the production of the aqueous resin dispersion used in the present invention has an average degree of polymerization of 300 to 300.
4200, partially saponified products or completely saponified products with a saponification degree of 70 to 100 mol% are used, and unsaturated carboxylic acids such as acrylonitrile, acrylamide, crotonic acid, acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc. are used during the polymerization process. Water-soluble so-called modified PVA or PVA, such as those obtained by copolymerizing acids or their alkyl esters with vinyl acetate and then saponifying them, or those obtained by reacting with sulfuric acid, phosphoric acid, formalin, urea, maleic anhydride, etc. after producing PVA. Derivatives can also be used. The amount used is 1 to 15% by weight based on the ethylene-vinyl ester copolymer resin content, and 1
If it is less than 15% by weight, the effect of adding isocyanate will be small, and if it is more than 15% by weight, the adhesive strength to rubber, plastic, etc. will decrease. Isocyanate compounds to be added to the aqueous resin dispersion used in the present invention include polyisocyanate compounds having two or more isocyanate groups in one molecule, and combinations of these polyisocyanate compounds with, for example, phenols, alcohols, oximes, and amides. Examples include reaction products with at least one compound selected from the group consisting of imides, lactams, bisulfites, and ethyleneimine. Polyisocyanate compounds include tolylene diisocyanate (TDI), xylidene diisocyanate (XDI), naphthalene diisocyanate (NPDI), hexamethylene diisocyanate (HDI), methylene bis(4-phenyl isocyanate (MDI), isophorone diisocyanate (IPDI), Methylolpropane-TDI adducts and prepolymers derived therefrom are polyvalent isocyanates.When adding the above polyisocyanates to an aqueous resin dispersion, adding them alone increases the viscosity of the system in a short period of time, making it usable. Since the time is short, it is preferable to dilute it appropriately with a hydrophobic solvent.Hydrophobic solvents are those with a water solubility of 5% or less at 20°C, such as toluene, xylenes, kerosene, liquid paraffin, etc. Examples include phthalic acid esters such as dibutyl phthalate, chlorinated paraffins, etc. Polyisocyanate compounds and phenols, alcohols, oximes, amides, imides,
When adding a reaction product with at least one compound selected from the group of lactams, bisulfites, and ethyleneimine, it should be dissolved in the solvent of the reaction product, not limited to hydrophobic solvents, and added. Alternatively, an aqueous dispersion prepared by a known method may be added. The amount of isocyanate compound added is present in the ethylene-vinyl ester copolymer aqueous dispersion.
The effective isocyanate group is added in an amount of 0.1 to 1.0 mole per mole of hydroxyl group of PVA. 0.1
If it is less than molar, the adhesive performance, especially the heat resistance, will be insufficient.
Even if 1.0 mol or more is added, the heat resistance hardly changes and it is economically disadvantageous. Furthermore, the adhesive composition of the present invention may be mixed with an aqueous dispersion of other polymers as required, such as vinyl acetate polymers, ethylene-vinyl acetate copolymers, alkyl acrylates, etc. Examples include aqueous dispersions of ester copolymers, olefin polymers, vinyl chloride polymers, styrene-butadiene copolymers, and the like. Furthermore, the adhesive composition of the present invention may contain other commonly used additives such as thickeners, tackifiers, antifoaming agents, plasticizers, pigments, etc. As in the case of mixing other aqueous polymer dispersions, the amount is limited to an extent that does not reduce the performance of the composition. The aqueous contact adhesive composition of the present invention can be applied to plastics, films, cloth, paper, vinyl chloride, plywood,
It is also useful as an adhesive for mortar, foam, etc., and is particularly useful as an adhesive for waterproof sheets. "For waterproof sheets" refers to the adhesion between waterproof sheets and between waterproof sheets and mortar, concrete, and asphalt coatings, and such waterproof sheets are sheets used in sheet waterproofing methods for roofs, underground structures, water tanks, etc. Generally available butyl rubber sheet, natural rubber sheet, chloroprene rubber sheet, polyisobutylene sheet, EPT sheet,
Polyvinyl chloride sheets etc. are mainly used. The composition of the present invention is particularly suitable for use with materials having low surface energy. The aqueous contact adhesive composition of the present invention also adheres well to various foams, especially plastic foams such as polystyrene, polyurethane, polyethylene, polypropylene foams, etc., and also adheres well to inorganic materials such as mortar, gypsum materials, etc.
It adheres well to calcium carbonate materials and even cellulosic materials, making it useful for bonding foam to all materials, and also to gypsum,
Rock wool, glass wool, calcium carbonate,
It is also effective for inorganic foams made of magnesium oxide, pearlite, etc. Hereinafter, the present invention will be specifically explained with reference to experimental examples and examples, but these examples are not intended to limit the present invention in any way. Note that "parts" and "%" in these examples are based on weight unless otherwise specified. Experimental Example 1 Preparation of Aqueous Dispersion A An autoclave equipped with a stirring device and a jacket capable of controlling the temperature, with an average degree of polymerization of 1700,
5 parts of PVA with a degree of saponification of 88 mol% was dissolved in 70 ^parts of water, 0.5 parts of dibasic sodium phosphate, and a vinyl ester of a tertiary carboxylic acid having an average carbon number of 10 ( 74 parts of Veova-10 (manufactured by Ciel Chemical Co., Ltd.) and 4.5 parts of vinyl acetate were continuously polymerized using a 2% aqueous solution of ammonium persulfate. The obtained aqueous dispersion had a solid content concentration of 51.1%, a viscosity of 1580 centipoise (hereinafter abbreviated as CP), and a pH of 4.2. According to the NMR measurement results, the weight ratio was ethylene:Veova-10:vinyl acetate=
The composition was 22.3:73.2:4.5. Experimental example 2 Preparation of aqueous dispersion B Average polymerization degree in the same autoclave as in experimental example-1
2000, 2 parts of PVA with a degree of saponification of 88 mol% and 3 parts of a nonionic activator (Nonipol 400, manufactured by Sanyo Kasei) were dissolved in 70 parts of water, and 50 kg/cm ² of ethylene was dissolved under pressure with 0.5 part of dibasic sodium phosphate and Veova. 10.10 parts and vinyl acetate
15.5 parts ammonium persulfate 4% aqueous solution and l at 60°C.
-Continuous polymerization using ascorbic acid 4% aqueous solution. The resulting aqueous dispersion had a solid content concentration of 50.9%, a viscosity of 560 cp, and a pH of 3.8. According to the NMR measurement results, the weight ratio was ethylene: Veova-10: vinyl acetate = 30.0:
The composition was 54.8:15.2. Experimental Example 3 Preparation of Aqueous Dispersion C Nonipole was placed in the same autoclave as Experimental Example-1.
400 (manufactured by Sanyo Chemical) and 1 part of an anion activator (Neoperex 05, manufactured by Kao Sekiken) were dissolved in 70 parts of water, and dibasic sodium phosphate and Veova were added as a PH regulator under pressure of ethylene 30 kg/ ^cm2 . -10.80 parts of vinyl propionate, 11 parts of vinyl propionate, and 0.5 parts of diallyl phthalate were added and mixed, followed by continuous polymerization at an internal temperature of 60°C using a 2% aqueous solution of ammonium persulfate. At the same time, 10 parts of a 20% aqueous solution of Nonipol 400 was also continuously added. After the addition was complete, the reaction was continued for an additional hour. The resulting aqueous dispersion had a solids concentration of 49.1% and a viscosity of
350cp, based on the NMR measurement results, the weight ratio is ethylene:Veova-10:vinyl propionate:DAP=
The composition was 11.2:78.5:9.8:0.5. Experimental Examples 4 to 7 Preparation of aqueous dispersions D, E, F, and G Using the same polymerization method as Experimental Example-2, ethylene pressure,
Veova-10, No. 4 in Table-1 by changing the amount of vinyl acetate
Aqueous dispersions of ~7 were prepared. Example 1 To 100g of the aqueous dispersion A obtained in Experimental Example-1,
MDI (hereinafter abbreviated as C-MDI) (Millionate MP-
100) as dibutyl phthalate (hereinafter abbreviated as DBP)
Crosslinking agent (A) diluted with (C-MDI/DBP=1/1)
A composition was prepared by adding 10 g of the compound, and an adhesion test between a butyl rubber waterproof sheet and a flexible board was conducted under the following conditions.

【table】

【table】

[Table] Adhesive conditions: Apply the composition to the flexible board with a roller at a coating amount of 200 g (wet)/m ² and leave an open time of 30 minutes 25 mm (width) x 100 mm (length)
A butyl rubber sheet (manufactured by Toyo Tire & Rubber Co., Ltd.) was pressed once with a roll, and after curing for one day at 20°C, adhesive force measurement tests (1) to (4) were conducted. (1) Normal peel strength Peel strength 180°, peeling speed 200mm/min, measurement temperature
Measurement was performed using an autograph at 20°C. (2) Water resistant peel strength Peel strength was measured according to (1) in a wet state after being immersed in tap water at 20°C for one week. (3) High-temperature peel strength Peel strength at 50°C (peel angle 180°, peeling speed
200mm/min). (4) Aging resistance test 24 hours in a desiccator at 60℃90%RH (relative humidity)
After standing for a period of time, normal peel strength was measured. Normal peel strength is 4.5Kg/25mm, water resistant peel strength is 4.3
Kg/25mm, high temperature peel strength 3.9Kg/25mm, normal peel strength after aging test 4.4Kg/25mm, and had excellent contact and adhesive properties. Examples 2 to 5, Comparative Examples 1 to 4 Crosslinking agent (A) was added to the aqueous dispersions B to G obtained in Experimental Examples 2 to 7 in the same manner as in Example 1, and the compositions shown in Table 2 were prepared. A product was prepared and an adhesion test between a flexible board and a butyl rubber sheet was conducted. However, in Example 3, the aqueous dispersion C had an average polymerization degree of 500 and a saponification degree of 88.
A composition was prepared by adding 15 g of a 20% aqueous solution of mol % PVA and then adding 10 g of the crosslinking agent (A). Moreover, Comparative Example 1 is a system in which no crosslinking agent is added. The results are also shown in Table 2. As is clear from the table, compositions 2 to 5 of the present invention have excellent adhesive performance, but those without the addition of a crosslinking agent, those containing no PVA, and the composition of the copolymer are outside the scope of the present invention. The adhesive had poor adhesive performance. Example 6 To 100g of the aqueous dispersion A obtained in Experimental Example-1,
MDI (hereinafter abbreviated as C-MDI) (Millionate MR
-100) diluted with dibutyl phthalate (hereinafter abbreviated as DBP) (C-ADI/DBP=
1/1) was added to prepare a composition, and an adhesion test between polyethylene foam and flexible board was conducted under the following conditions. Adhesion conditions: Apply the composition to the flexible board with a roller at a coating amount of 300 g (wet)/m ² and leave it open for 30 minutes. Thickness: 20 mm, width: 25 mm, length: 100 mm
mm polyethylene foam (manufactured by Toray Industries, Ltd.) was pressed once with a roller, and after curing for one day at 20° C., adhesive force measurement tests (1) to (4) were conducted. (1) Normal peel strength Peeling angle 90°, peeling speed 200mm/min, measurement temperature 20°
It was measured using an autograph under the conditions of ℃. (2) Water resistant peel strength Peel strength was measured according to (1) in a wet state after being immersed in tap water at 20°C for one week. (3) High temperature creep test Shear creep was measured under a load of 200g at 70°C (adhesion area: 25mm x 25mm) (4) Aging resistance test In a desiccator at 60°C and 90% RH (relative humidity).
After standing for 24 hours, normal peel strength was measured. Normal peel strength is 1.5Kg/25mm (100% foam material breakage), water resistant peel strength is 1.5Kg/25mm (100% foam material breakage),
In the high temperature creep test, the creep in 30 minutes is 0.0mm, and the normal peel strength after aging resistance test is 1.5Kg/25mm (100%
The contact and adhesion properties were excellent. Examples 7 to 10, Comparative Examples 5 to 8 Crosslinking agent (A) was added to the aqueous dispersions B to G obtained in Experimental Examples 2 to 7 in the same manner as in Example 6, and the compositions shown in Table 3 were prepared. A product was prepared and an adhesion test between a flexible board and polyethylene foam was conducted. However, in Example 8, a composition was prepared by adding 15 g of a 20% aqueous solution of PVA having an average degree of polymerization of 500 and a degree of saponification of 88 mol % to the aqueous dispersion C, and then adding 10 g of the crosslinking agent (A). Comparative Example 5 is a system in which no crosslinking agent is added. The results are also shown in Table 3. As is clear from this table, Examples 7 to 10, which are compositions of the present invention, have excellent adhesive performance, but those without the addition of a crosslinking agent, those without PVA, and those with a copolymer composition of the present invention Those outside the range had low adhesive performance. Example 11 Using the composition of Example 6, an adhesion test between urethane foam and flexible board was conducted. Adhesion conditions and adhesive force measurement conditions were the same as in Example 1. Normal peel strength is 2.0Kg/25mm (100% foam material break),
Water resistance peel strength is 2.0Kg/25mm (100% foam material break), high temperature creep test shows 30 minute creep is 0.0
mm, normal peel strength after aging resistance test 2.0Kg/25mm
(100% foam material breakage) and has excellent adhesive performance.

【table】

【table】

Claims (1)

[Scope of Claims] 1 Contains polyvinyl alcohol, and contains 5 to 50% by weight of ethylene, 50 to 95% by weight of vinyl ester of higher carboxylic acid having 5 to 12 carbon atoms, and vinyl of lower carboxylic acid having 2 to 4 carbon atoms. An aqueous contact adhesive composition prepared by adding an isocyanate compound to an aqueous dispersion of an ethylene-vinyl ester copolymer having a copolymerization composition of 0 to 45% by weight of ester. 2. The aqueous contact adhesive composition according to claim 1, wherein the aqueous contact adhesive composition is an adhesive composition for a waterproof sheet.