JPS60258276A - Water-resistant elastic adhesive - Google Patents

Abstract

PURPOSE:To provide the titled adhesive consisting of the first liquid composed of an ethylene-vinyl acetate copolymer emulsion and the second liquid composed of a polyisocyanate compound, suitable for the production of an elastic mat, the base of a TATAMI mat, etc. having high air permeability and water resistance, and available at a low cost. CONSTITUTION:The objective adhesive can be prepared by mixing (A) an ethylene-vinyl actate copolymer with (B) a polyisocyanate compound in the presence of a proper amount of water. The adhesive is applied to or mixed with an adhered and heated at 140-160 deg.C to obtain a bonded product. The sum of the solid content of the component A and the component B is preferably 40-60(wt)% of the mixture, and the content of water is preferably 60-40%. The weight ratio of the component B to the component A is preferably 0.3-0.6 to 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides water-resistant and water-resistant materials suitable for molding breathable, water-resistant elastic mats, tatami floors, etc. using hydrophobic fine particles such as rice husks and cork pieces as raw materials. It relates to adhesives with excellent elasticity.

Traditionally, fine particles such as rice husks are used as raw materials.

When molding mats with excellent water resistance and elasticity, such as tatami floor or carpet undermats, strict requirements are placed on the performance and cost of the adhesive used, and to date no adhesive is known that can meet these requirements. .

Rice husks are naturally hydrophobic and do not rot easily, but when compression molded and used as tatami flooring, the adhesive used to hold the shape must have excellent water resistance. . In other words, when making tatami floors using rice husks, moisture in the atmosphere is absorbed by the voids in the tatami mats, which can sometimes lead to water seepage, so the adhesive used must be highly water resistant. However, from the viewpoint of water resistance, conventional urea-based adhesives and vinyl acetate-based adhesives are generally unsuitable. Furthermore, tatami floors are required to have strong elasticity with a unique tactile feel, and from this elasticity point of view, thermosetting adhesives based on phenol resins or urea resins are unsuitable. Furthermore, in the case of tatami floors made from rice husks, in order to maintain their breathability, the compression ratio cannot be increased during molding, and the compression ratio must be kept within a certain limited range. However, in this case, since the contact density between the rice husks is reduced, the adhesive used must have a stronger adhesive force.

In general, there are isocyanate-based, rubber-based, and epoxy resin-based adhesives that have excellent water resistance, elasticity, and strong adhesion, but these are all expensive and do not work well on rice husk tatami floors. It is not suitable for large-scale processing such as manufacturing, and has the disadvantage that it is difficult to uniformly wet fine particles due to its high viscosity.

In view of the above-mentioned circumstances, the present inventor has conducted extensive research to develop an adhesive suitable for making rice husk tatami floors, and has finally completed the present invention.

That is, according to the present invention, there is provided a water-resistant, elastic adhesive comprising a first liquid consisting of an ethylene-acetic acid and nyl-based copolymer emulsion and a second liquid consisting of a polyisocyanate-based compound.

As the ethylene-vinyl acetate copolymer emulsion used in the present invention, various commercially available emulsions can be used, such as Denka EVA Tex (manufactured by Denki Kagaku Kogyo Co., Ltd.). In this case, the copolymer component may include, if necessary,
Other ingredients such as acrylic acid, maleic acid, fumaric acid, etc. may also be included. Examples of polyisocyanate compounds include ordinary incyanate compounds having two or more incyanate groups (NGO), such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and triphenylmethane triisocyanate ( TTI), etc.

In the case of the present invention, these polyisocyanate compounds can be used in the form of a prepolymer prepared using a polyol. In the case of the present invention, various products commercially available as isocyanate adhesive components can be used as they are as the polyisocyanate compound.

The adhesive of the present invention is mainly composed of an ethylene-vinyl acetate copolymer emulsion, which is combined with a polyisocyanate compound. In use, the adhesive of the present invention is applied in the form of a mixture by mixing both. In this case, the composition of the mixture is such that the total amount of the ethylene-vinyl acetate copolymer (solid content in the emulsion) and the polyisocyanate compound is 30 to 80% by weight, preferably 40 to 60% by weight. , and water content is 70-20% by weight.
, preferably adjusted to 60 to 40% by weight.

The polyisocyanate compound is preferably used in an amount of 0.1 to 0.8 parts by weight, preferably 0.3 to 0.6 parts by weight, per 1 part by weight of the ethylene-vinyl acetate copolymer. . In the present invention, when adding a polyisocyanate compound to the ethylene-vinyl acetate copolymer emulsion, the water content can be adjusted arbitrarily.For example, 'mixing an appropriate amount of water with the polyisocyanate compound, A method of adding and mixing this mixture to an ethylene-vinyl acetate copolymer emulsion, a method of adding water to an ethylene-vinyl acetate copolymer emulsion, and adding and mixing a polyisocyanate compound thereto, etc. are adopted. be able to.

The adhesive of the present invention is preferably applied as a two-component adhesive during transportation or storage that requires a long period of time, and mixed on site.

The adhesive of the present invention is a thermally crosslinkable adhesive, and after being applied or mixed onto an object, the adhesive is heated to a temperature of 120 to 180 °C, preferably 1
An adhesive can be obtained by heating to about 40 to 160°C.

Unlike conventional adhesives, the adhesive of the present invention has excellent water resistance and elasticity, and is inexpensive. In particular, the adhesive of the present invention is made from highly elastic fine particles such as rice husks, and is made from highly elastic particles such as rice husks. It is suitable as an adhesive for obtaining molded products. In order to obtain a tatami floor from rice husks using the adhesive of the present invention, the adhesive of the present invention is mixed with rice husks, and then pressure is applied from above and below using porous pressure plates. Hot air may be passed from the hole to the other porous pressurizer. In this case, the temperature of the hot air may be about 140 to 150°C.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Commercially available ethylene-vinyl acetate copolymer emulsion (hereinafter referred to as EVA) [trade name: Denka EVA #60 (
manufactured by Denki Kagaku Kogyo), solid content 55%, viscosity (cps)
2500, pH 4,5) 200g, polyisocyanate [Product name: Coronate C-3O53 (Japan Polyurethane Products), NGO content 29.4%, viscosity 240c
p/25℃] and 50 g of water, mixed with rice husk 11Q (apparent specific gravity approximately 0.1), and tested in a hot air blow-out type tester (30 cm x 30 cm, press pressure 3).
Compressed (kg/c+#) to a thickness of 5cm (standard tatami floor dimensions)
Compression ground assembly 2.2) L, hot air (temperature 140°C 1 wind force 0.3 kg/cJ) is applied from one porous pressure plate to the other porous pressure plate.
) was molded by blowing through it for about 30 minutes at an air volume of 5NM and 37 hours. Next, for a water resistance test, this molded product was immersed in cold water for 3 hours and taken out, but the volume of the molded product (4500
cc), the amount of water infiltrating into the void is approximately 2100cc,
The water release rate is 1700cc in about 20 minutes, and 1. If this is left at room temperature for 2 days, the water content will decrease to 1
During this period, no collapse, melting, or dissolution of the adhesive resin coating was detected, and no deformation such as blistering or collapse of the molded product occurred, and no partial peeling occurred.

Further, after drying, this molded product was immersed in warm water at 60° C. for 3 hours and then pulled out, but in this case as well, almost no change was observed as in the above case.

Comparative Example 300 g of EVA shown in Example 1 was mixed with rice husk 11Q and compressed to 5 cm using a hot air blow-out test machine (same machine as in Example 1) (120°C, 15C, 15N) for 30 minutes. . The obtained molded product had a strong shape and appearance with air permeability and elasticity as in Example 1, but
When this was immersed in cold water for a water resistance test, it was only 15
Within minutes, the adhesive resin coating was dissolved in water and washed away, lost its compressive force and adhesive force to the rice husks, swelled, and completely disintegrated after 30 minutes.

Example 2 A mixed solution of 3600 g of EVA shown in Example 1, 900 g of polyisocyanate shown in Example 1, and 900 g of water was mixed and stirred, mixed with rice husks 190Q, and heated in a full-scale hot air blower type tester (91 cm x 182 cm). ) and molded by blowing hot air (140°C1C11O0N/hour) through one porous pressure plate to the other porous pressure plate for 30 minutes. The obtained molded product was subjected to a water resistance test in the same manner as in Example 1, and as a result, it showed excellent water resistance, almost the same as in Example 1.

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Although the product is a +,・ product and there is no JIS standard set, the standard for foam polystyrene sandwich tatami flooring was applied mutatis mutandis, and the amount of deflection by the bending test specified therein and the amount of local compression by the local test were measured.

The results are shown in the table below.

The dimensions of the test product are the same as the standard product (91W): length 182 cm, width 91 cm, and thickness 5 cm.

Table 1 In addition, in the case of the adhesive of the present invention, by mixing EVA, polyisocyanate, and water, it foams and increases in volume (approximately 30
%), but this has the advantage of sufficiently uniformly wetting the ingredients to a large amount of fine particles, and the heating temperature is also
When the polyisocyanate shown in Example 1 is used alone, the heating temperature for reaction is 160°C to 180°C.
'C, whereas the adhesive of the present invention reacts completely at 140''C to 150°C, and the adhesive of the present invention is also advantageous in terms of thermal energy.

Patent applicant: Toshiaki Ikeura, patent attorney, Kindai Jisui Center Co., Ltd.

Claims (1)

[Claims] (1) A water-resistant, elastic adhesive composed of a first liquid consisting of an ethylene-vinyl acetate copolymer emulsion and a second liquid consisting of a polyisocyanate compound.