JPS5945382A - Urethane sealant - Google Patents

Abstract

PURPOSE:A sealant capable of maintaining permanently adhesiveness, elasticity, etc. of its own without causing bleeding phenomena of liquid plasticizer at all, obtained by blending a specific ethylene-vinyl acetate copolymer with a liquid plasticizer and a urethane prepolymer in a specified ratio. CONSTITUTION:(A) 100pts.wt. urethane preoplymer (e.g., isocyanate group-containing prepolymer having 1.5-4wt% end NCO group content, obtained by reacting ether polyol, etc. with organic polyisocyanate) is blended with (B) 5- 100pts.wt., preferably 5-80pts.wt. liquid plasticizer (e.g., dioctyl phthalate, etc.), and (C) 1-50pts.wt., preferably 15-35wt% ethylene-vinyl acetate copolymer containing 20-80wt%, preferably 45-65wt% vinyl acetate, usually an inert solvent and a catalyst for promoting curing are further added to the blended, to give the desired sealant.

Description

[Detailed Description of the Invention] The urethane sealant composition obtained by blending a liquid plasticizer with a urethane prepolymer has excellent properties, including good elasticity, adhesion, cold resistance, abrasion resistance, and chemical resistance. Taking advantage of these properties, it is widely used in civil engineering and construction as a joint material, adhesive, caulking material, etc.

However, after curing, the sealant composition tends to cause the so-called bleed phenomenon in which the mixed liquid plasticizer dissolves onto the coating surface over time, and there are problems such as the inability to maintain the above-mentioned excellent performance over a long period of time. be. Various attempts have been made to solve this problem, but no satisfactory solution has yet been found.

However, as a result of extensive research in order to solve the above-mentioned problems, the present inventors added 100 parts by weight of urethane prepolymer, 5 to 100 parts by weight of liquid plasticizer, and 1 part vinyl acetate copolymer (hereinafter abbreviated as EVA). -50 parts by weight of the composition does not cause any bleeding phenomenon of the liquid plasticizer, so the excellent properties originally possessed by urethane sealants such as adhesiveness, elasticity, and cold resistance are permanently maintained. The present invention was completed based on the discovery of the novel fact that

Since the combined use of a liquid plasticizer is essential for the practical use of urethane sealants, it is extremely useful industrially that the bleeding phenomenon of the plasticizer can be significantly prevented by incorporating EVA as in the present invention.

The urethane prepolymer used in the present invention is obtained by reacting polyols such as polyethylene glycol and polypropylene glycol, polyether polyols, and polyester polyols with an organic polyisocyanate and has a terminal NCO group content of 1 to 6%, preferably 1.5%. It consists of a prepolymer containing about 4% isocyanate groups.

Ethylene glycol as polyether polyol,
diethylene glycol, triethylene glycol, 1,
2-propylene glycol, dipropylene glycol,
Trimethylene glycol, 1,4 or 1,3-butylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, aconitic acid, trimellitic acid , hemimellitic acid, ethylene diamine, propylene diamine, diethylene triamine, triethanolamine, pyrogallol, dihydrobenzoic acid,
Hydroxyphthalic acid, resorcinol, hydroquinone,
At least two or more active hydrogen atoms in molecules such as bisphenol A (2,2-bis(4'-hydroxyphenyl)propane), bisphenol F (4,4'-dihydroxydiphenylmethane), 1,2-propanedithiol, etc. An addition polymer obtained by adding one or more of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide, etc. to one or more of the compounds having a molecular weight of 10
A polyether of 0 to 10,000, preferably 300 to 5,000 is used.

As polyester polyols, ethylene glycol, diethylene glycol, triethylene glycol, 1
, 2-propylene glycol, dipropylene glycol, trimethylene glycol, 1,4 or 1,3-butylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, glycerin, trimethylolpropane,
One or more compounds having at least two hydroxyl groups in the molecule, such as pentaerythritol, sorbitol, etc., and malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, pimelic acid, cepacic acid, oxalic acid. , phthalic acid, terephthalic acid, hexahydrophthalic acid,
A condensation polymer of one or more compounds having at least two carboxyl groups in the molecule, such as aconitic acid, trimellitic acid, hemimellitic acid, etc., is used.

Examples of the organic polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
2,4 and 2,6-tolylene diisocyanate mixture,
4,4'-diphenylmethane diisocyanate, m-phenylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate ester,
1,4-cyclohexylene diisocyanate, 4,4'
-dicyclohexylmethane diisocyanate, 3,3'
-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1, 5-tetrahydronaphthalene diisocyanate and the like are used.

Crude tolylene diisocyanate or 4,4'-diphenylmethane diisocyanate or carbodiimide-modified 4
, 4'-diphenylmethane diisocyanate may also be used.

The above organic polyisocyanates may be used alone or as a mixture of two or more.

Next, any liquid plasticizer used in the present invention can be used as long as it is liquid at room temperature.

Phthalic acid esters such as dioctyl phthalate, butyl benzyl phthalate, dinonyl phthalate, benzoic acid esters such as diethylene glycol dibenzoate, ethylene glycol monobutyl ether benzoate, partially hydrogenated terphenyls, alkyl polycyclic aromatic hydrocarbons, Any commonly used ones such as chlorinated paraffins or mixtures thereof may be used, and the amount is usually 5 to 1 part by weight per 100 parts by weight of the urethane prepolymer.
00 parts by weight, particularly preferably 5 to 80 parts by weight.

If the amount of plasticizer added is less than 5 parts by weight, a sufficient plasticizing effect cannot be obtained, while if it is more than 100 parts by weight, problems such as bleeding phenomenon and the resulting decrease in adhesive strength and elasticity become noticeable.

In the present invention, EVA is blended in order to prevent the plasticizer from bleeding.

The EVA should have a composition with a vinyl acetate content of 20 to 80% by weight, preferably 45 to 65% by weight. If the vinyl acetate content is less than 20% by weight, the solubility and dispersibility will be poor and the elasticity will be reduced, while if it is more than 80% by weight, the flexibility will be poor and the cold resistance will be reduced, both of which are impractical.

In addition to ethylene and vinyl acetate components, the EVA contains small amounts of other components such as carboxylic acids, carboxylic acid esters, carboxylic acid amides, nitriles, α-olefins, alkyl vinyl ethers, vinyl alcohol, and olefin sulfonic acids. You can let me.

The EVA is blended in an amount of 1 to 50 parts by weight, preferably 15 to 35 parts by weight, per 100 parts by weight of the urethane prepolymer. If the amount is less than 1 part by weight, the effect of preventing plasticizer bleed will be poor, while if it is more than 50 parts by weight, problems will arise in the fluidity and ejectability of the sealant. The EVA can be blended in any form such as powder, block, or solution.

In practical use, an insoluble solvent and a catalyst for accelerating curing are usually added to the polyurethane sealant of the present invention.

The inert solvent may be any of the commonly used inert solvents, such as aromatic solvents such as toluene and xylene, esters, ketones, and ethers. It is preferable to mix them in proportions.

As curing accelerating catalysts, N-alkylbenzylamine, N-alkylmorpholine, N-alkyl aliphatic polyamine, N-alkylpiperazine, triethylenediamine, 1,8-biazacyclo[5.4.0]undecene-7
tertiary amines and other nitrogen-containing compounds, such as copper, copper, blue lead, cobalt, manganese, and its derivatives, etc.
Naphthenic acid or octenoic acid salts of heavy metals such as iron and mercury, dibutyltin dilaurate, dibutyltin maleate,
Examples include heavy metal organic compounds such as di(phenylmercury)dodecenyl succinate, and these are usually preferably blended in a proportion of 10 parts or less per 100 parts of the urethane prepolymer.

Furthermore, it is also possible to mix and use fillers such as crosslinking agents such as polyalkylene glycol, various fillers, thixotropic agents, bituminous materials, and pigments, as required.

Examples of such fillers include calcium carbonate, perlite, silica oxide, talc, vermiculite, wollastonite, glass, carbon black, vinyl chloride resin, and the like.

Examples of thixotropic agents include bentonite, resin-coated bentonite, metal soap, hydrogenated castor oil,
Examples include asbestos powder.

Further, examples of bituminous substances include coal tar, negative rock tar, wood tar, oil gas tar, petroleum tar, petroleum asphalt, and pitches.

In the polyurethane sealant of the present invention, 2 to 2 to 100 parts of filler is added to 100 parts of the above isocyanate group-containing polymer.
The composition preferably contains 100 parts, preferably 10 to 70 parts.

The polyurethane sealant of the present invention can be used, for example, at each joint of various buildings or structures such as corrugated boards, slates, plastic boards, aluminum boards, and galvanized iron, joints of concrete, ceramic pipes, glass, etc., joints of roads and floor coverings, and automobiles. It can be used as a joint material, adhesive, caulking material, etc. for joints and joints of vehicles such as ships and aircraft, pipes and joints of prefabricated buildings, etc.

Methods for using the polyurethane sealant of the present invention include, for example, an injection method in which the above-mentioned sealant is injected in liquid form into the gaps and joints of the target materials and hardened, and a spray method in which the undiluted solution is sprayed onto the joints of the materials and hardened. There are two methods: a brush coating method in which an undiluted solution is applied to the material with a brush and the material is cured, and an installation method in which a pre-cured sealant is attached as it is or a processed sealant is attached to fill the gap.

Next, the present invention will be explained in more detail by giving examples.

"%" and "part" are based on weight unless otherwise specified.

Example 1 A polyurethane sealant having the following composition was prepared.

A bleed test was conducted on the sealant.

(Test-I) Stack 5 sheets of paper and place a 2cm wide and 1cm thick sheet on top of it.
A sealant coating film with a length of 10 cm was formed, and after one week, it was observed to what number of sheets of paper the plasticizer had bleed.

(Test-II) A test similar to Test-I was conducted except that newspaper was used instead of paper.

(Test-III) Place asphalt paper on top of 5 sheets of newspaper, form a sealant film of 2 cm width, 1 cm thickness, and 10 cm length on top of it, and after one week, asphalt paper is placed on top of it. It was observed whether the plasticizer bleed.

Furthermore, an alkyd resin was coated on the sealant coating, and after drying, cellophane tape was attached and then peeled off to test the adhesive strength of the sealant.

In addition, contamination due to bleeding on the surface of the sealant was also measured based on JISA5758.

These results are shown in the table.

As Control Example 1, the same experiment as in Example 1 was conducted except that the use of EVA was omitted. This result is also shown.

Examples 2 to 3 Vinyl acetate content of EVA is 45% (Example 2) and 65%
The same experiment as in Example 1 was conducted except that (Example 3) was replaced.

The results are shown in the table.

Examples 4 to 5 The same experiment as in Example 1 was conducted except that the amount of dioctyl malate used was changed to 35 parts (Example 4) and the amount of EVA used was changed to 35 parts (Example 5). The results are shown in the table.

Examples 6-7 The same experiment as in Example 1 was conducted except that the plasticizers were changed to butylbenzyl phthalate (Example 6) and diisodecyl phthalate (Example 7). The results are shown in the table.

Control Examples 2 and 3 The same experiment as in Example 1 was conducted except that the amount of EVA used was changed to 0.5 parts (Control Example 2) and 80 parts (Control Example 3). The results are also shown in the table.

Claims (1)

[Claims] 5 to 5 parts of liquid plasticizer to 100 parts by weight of urethane prepolymer
A urethane sealant containing 100 parts by weight and 1 to 50 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 20 to 80% by weight.