JPH01146978A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain an adhesive good in water resistance and alkali resistance and giving a cured product excellent in adhesiveness and flexibility, by mixing a urethane-modified epoxy resin with an epoxidized natural rubber and a curing agent. CONSTITUTION:This adhesive composition comprises a urethane-modified epoxy resin, an epoxidized natural rubber and a curing agent. The urethane-modified epoxy resin used is obtained by reacting a compound (a) having epoxy and hydroxyl groups with an isocyanate-terminated urethane compound (b) obtained from a polyhydroxyl compound and a polyisocyanate compound. Said epoxidized natural rubber is obtained by epoxidizing a natural rubber by oxidizing part of the double bonds of a natural rubber latex. As said curing agent, any of general curing agents for epoxy resin can be used, and various adhesive compositions including one-pack and two-pack types or room temperature- curable and heat-curable types can be formed by varying the properties of the curing agent used.

Description

Detailed Description of the Invention (1) Technical Field The present invention relates to an adhesive composition, and more particularly to a novel adhesive composition that is an epoxy resin composition and has excellent flexibility.

! ■ Conventional technology Conventional epoxy resin adhesives have high adhesive strength to adherends such as metal, wood, concrete, and mortar, but the cured product is hard and has poor flexibility, and has poor resistance especially at low temperatures. It had the disadvantage of being weak against impact.

On the other hand, as flexible epoxy resins, glycidyl ester type, polyoxyalkylene glycol type, bisphenol A propylene oxide addition type, etc. are known.

However, when these flexible resins are used, they have the drawbacks of slow curing speed and poor water resistance and alkali resistance.

III. OBJECTS OF THE INVENTION An object of the present invention is to provide a novel adhesive composition that has good water resistance and alkali resistance, and has excellent adhesiveness and flexibility of a cured product.

IV Specific Structure of the Invention The present invention provides an adhesive composition characterized by containing a urethane-modified epoxy resin, epoxidized natural rubber, and a curing agent.

The configuration of the present invention will be explained in detail below.

(1) Urethane-modified epoxy resin The urethane-modified epoxy resin used in the present invention comprises (a) a compound having an epoxy group and a hydroxyl group, and (b)
It is obtained by reacting a polyhydroxyl compound with a urethane bond-containing compound containing an isocyanate group at the end obtained from a polyisocyanate compound.

(a) The compound having an epoxy group and a hydroxyl group is a compound having 1 to 3 epoxy groups and 1 to 2 hydroxyl groups in the molecule, and preferably has a molecular weight of 7.
0 to 2000 compounds. Examples include glycidyl ethers of polyhydric alcohols such as glycidol, ethylene glycol monoglycidyl ether, and glycerin diglycidyl ether, and commercially available epoxy resins having hydroxyl groups.

(b) The urethane bond-containing compound containing a terminal isocyanate group is produced by the reaction of (bi) a polyhydroxyl compound and (b-2) a polyisocyanate compound.

(b-1) As the polyhydroxyl compound, for example,
Various polyester polyols or polyether polyols used for producing the urethane compound of -11Q can be mentioned.

The polyester polyols mentioned here include condensates of polyhydric alcohols and polybasic carboxylic acids, condensates of hydroxycarboxylic acids and polyhydric alcohols, etc. The polyhydric alcohols used in these include, for example, ethylene glycol, propylene glycol, butanediol,
Examples of polybasic carboxylic acids include diethylene glycol, glycerin, hexanetriol, and trimethylolpropane. Examples of polybasic carboxylic acids include adipic acid, geltaric acid, azelaic acid, fumaric acid, maleic acid, phthalic acid, terephthalic acid, dimer acid, and pyromellitic acid. Examples include acids.

In addition, condensates of hydroxycarboxylic acids and polyhydric alcohols include castor oil, castor oil and ethylene glycol,
Reaction products such as propylene glycol are also useful.

Examples of polyether polyols include ethylene oxide, propylene oxide, butylene oxide,
It is a product obtained by addition-polymerizing one or more alkylene oxides such as tetrahydrofuran with a compound having two or more active hydrogens, and any known polyether polyol used in the production of ordinary polyurethane resins can be used. I can do it. In this case, examples of compounds having two or more active hydrogens include, in addition to the polyhydric alcohols and polybasic carbonic acids mentioned above, ethylenediamine,
Examples include amines such as hexamethylene diamine, alkanolamines such as ethanolamine and propatoolamine, polyhydric phenols such as resorcinol and bisphenol, and castor oil.

(b-2) Polyisocyanate compounds used in the production of urethane bond-containing compounds containing isocyanate groups at the terminals are compounds that have two or more isocyanate groups in the molecule, and are used in the production of ordinary polyurethane resins. Various compounds can be used, such as tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, triphenylmethane triisocyanate, and the like.

The urethane-modified epoxy resin used in the present invention has the above (
It is preferably produced as follows using a), (b-1) and (b-2).

The urethane bond-containing compound containing an isocyanate group at the end can be obtained by reacting a polyhydroxyl compound and a polyisocyanate compound in the same manner as in the production method of a usual incyanate group-containing urethane prepolymer.

The urethane-modified epoxy resin used in the present invention can be obtained by reacting a urethane bond-containing compound containing an isocyanate group at the end with the above-mentioned epoxy group and hydroxyl group by a conventional method.

(2) Epoxidized natural rubber The epoxidized natural rubber used in the present invention is obtained by oxidizing a portion of the double bonds of natural rubber latex to epoxidize it.

For oxidation, for example, those using peracetic acid are commercially available, and these may be used.

Such epoxidized natural rubber is compatible with epoxy resin, and when mixed with the epoxy resin, it imparts excellent flexibility to the epoxy resin composition and also imparts tackiness, so that the composition is Improves initial adhesion.

The epoxidation rate due to oxidation of the natural rubber used in the present invention is:
The content of double bonds in natural rubber is preferably 20% or more, preferably 30% or more.

This is because if it is less than 20%, the compatibility with the epoxy resin will be poor and the adhesiveness of the cured product will be reduced.

The amount of epoxidized natural rubber blended is preferably in the range of 20 to 150 parts by weight, more preferably 30 to 130 parts by weight, based on 100 parts by weight of the urethane-modified epoxy resin.
Part by weight. .

If the amount of epoxidized natural rubber is less than 20 parts by weight, flexibility and low-temperature properties will be poor, and if it is more than 150 parts by weight, adhesiveness will be poor.

(4) Curing agent The curing agent used in the present invention can be a wide range of general curing agents for epoxy resins, and by changing the properties of the curing agent used, it can be made into a wave type, two-component type, room temperature curing type, etc. Various adhesive compositions can be used, such as a heat-curable adhesive composition.

For example, aliphatic polyamines, aromatic polyamines, modified aliphatic polyamines, boria, door.

various mercaptan-based curing agents, liquid NBR1 acid anhydride with an amino group at the end, boron trifluoride-amine,
One or more latent curing agents such as complexes, tertiary amines, etc. are used.

The amount of curing agent used is not particularly limited, but preferably 10 to 2 parts by weight per 100 parts by weight of the urethane-modified epoxy resin.
00 parts by weight.

In the present invention, in addition to the above-mentioned essential components, various polymers, additions, processing, etc. can be added as necessary.

For example, solvents, diluents, tackifiers, tackifiers
, anti-sagging agents, fillers, curing accelerators, pigments, adhesion promoters, antifoaming agents, leveling agents, polymerizing agents, rubbers, plasticizers, heat-resistant anti-aging agents, and other additives.

As the solvent, preferably use xylene, toluene, methyl ethyl ketone, etc.; as the tackifier, petroleum resin type, natural product type, etc.; as the filler, silica, talc, calcium carbonate, clay, calcium silicate, etc. are preferably used. Can be done.

In particular, by adding a third component adapted to the adhesion conditions of the adherend, etc., adhesive compositions having various properties can be obtained.

When the composition of the present invention is a two-component type, the urethane-modified epoxy resin, epoxidized natural rubber, and other necessary components are kneaded to form the main component, and the epoxy resin curing agent and other necessary components are kneaded to form the curing agent. , a two-component room temperature curing adhesive composition may be used.

The adhesive composition of the present invention may be used for any adherend, but it adheres well to concrete, mortar slate, metals such as iron, wood, plastics such as polyvinyl chloride, and the like.

(2) Examples The present invention will be specifically explained below with reference to Examples and Comparative Examples.

In Examples and Comparative Examples, compositions were prepared using the ingredients and number of parts shown in Table 1.

In the example, epoxidized natural rubber was masticated with a roll, then dissolved in toluene, and a urethane-modified epoxy resin and other predetermined raw materials were added and mixed to obtain a liquid A.

On the other hand, Liquid A of Comparative Example was obtained in the same manner as in the Example with the formulation shown in Table 1.

Liquid B was obtained by adding and mixing a curing agent, a solvent, and other predetermined raw materials.

Using a polyvinyl chloride sheet as the adherend,
Slate (JIS-A-
5403 Flexil Board) was used.

As shown in FIG. 1b, the polyvinyl chloride sheet 2 is a short strip-shaped sheet with a width of 25 mm and a length of 200 mm.
Slate board 1 has a width of 50 mm, a length of 200 mm, and a thickness of 4 m.
m was used.

The adhesive is obtained by mixing liquids A and B, and is uniformly applied to the surface of the slate board 1 in the comb direction 4 using a comb trowel, and then cured under normal conditions (20±2°C, 60±10% RH) 48 After a period of time, a test piece was used, and the following tests were conducted and evaluated. The results are shown in Table 1.

(1) Peel Adhesive Strength A 90 degree peel test was conducted at a tensile rate of 200 mm/min to evaluate the normal adhesive strength.

Alkali resistance was determined by immersing a test piece in a 0.1% aqueous sodium hydroxide solution for 48 hours and performing a 90 degree peel test.

(2) Elongation at 20℃ and -10℃ τ atmosphere at a speed of 200mm/
The elongation was measured by applying a tensile load of min.

(3) Cracking resistance As shown in Figure 1a, a cut 6 is made to a depth of 3.5 mm in the center of one side of the slate plate of the test piece 10 using a hacksaw.
In an atmosphere of -10℃, a tensile load was applied at a speed of 200 mm/min, and after the slate plate 1 broke, it was further
The presence or absence of breakage of the sheet 2 was observed when a tensile load of 0 mm was continuously applied.

(4) In the same way, the polyvinyl chloride sheet 2 was adhered to the initial adhesive slate plate 1 via the adhesive 3, and the test piece immediately after adhesion without normal curing was subjected to a 90 degree peel test at a tensile speed of 200 mm/min. Initial tack was evaluated.

Acceptable: 90 degree peel test 100 g / 25 mm Not allowed: 90 degree peel test 100 g / 25 mm
Less than m table 1 Note 1), 2) Urethane modified epoxy resin 3) Bisphenol A epoxy resin Epoxy fic 190 Sumitomo Chemical Aji ELA 128 4) Bisphenol A propylene Epoxy equivalent 500 Oxide addition type epoxy resin Manufactured by Asahi Denka Kogyo ■ EP 40055) Dimer acid-modified epoxy resin Epoxy equivalent 650 Oil-based shell epoxy ■ Epicoat 8726) ATBN Terminal amine N
BR (Guttrich Chemical Co., Ltd. Hiker HY, 1 (YC)
ARATBN 1300X16) 7) Epoxidized natural rubber Epoxidation rate 25% 8) Epoxidized natural rubber Epoxidation rate 50
%9) Thermoplastic urethane Dainippon Ink■
Manufactured by Pandex T-520510) Vinyl chloride, vinyl acetate copolymer manufactured by UCC VINYLITE U
YIIHll) Tackifier Finton 1500 manufactured by Nippon Ze Daini...In addition, the oven assembly time during adhesion, that is, the time from applying the adhesive to aligning the bonding surfaces and depositing the adhesive, is the same in all examples. It was 20 minutes.

(2) Effects of the Invention Since the adhesive composition of the present invention contains a urethane-modified epoxy resin, epoxidized natural rubber, and a curing agent, it has the following effects.

(1) Excellent flexibility (2) Large elongation (3) Excellent low temperature properties (4) Good water resistance and alkali resistance

[Brief explanation of the drawing]

FIG. 1a is a cross-sectional view of the test specimen. FIG. 1b is a plan view of FIG. 1a. Explanation of symbols 1... Slate board, 2... Sheet, 3... Adhesive, 4... Comb direction, 5... Tensile direction, 6.
...Depth of cut, 10...Test piece

Claims (1)

[Claims] (1) An adhesive composition characterized by containing a urethane-modified epoxy resin, epoxidized natural rubber, and a curing agent.