KR970010859B1 - Method for preparing hot-melt adhesives - Google Patents

Abstract

The moisture-curable polyurethanic hot melt adhesive which may adhere to various substrate such as leather, glass, aluminium, iron, wood, cotton, vinyl, polypropylene and polyethylene is maded by incorporating isocyanate group into both ends of polyurethane without treating the substrate with primer. Diisocyanate compound is heat melted at a temperature of 30-80 degree.C, then dihydroxy compound and the diisocyanate compound being in the ratio of 0.33-1 mole to 1 mole and other additives are added. The resultant mixture is polymerized at a temperature of 50-150 degree.C for 1 to 6 hours to provide hot melt adhesive. The used diisocyanate compound comprises aromatic diisocyanate compounds such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 1,5-naphthalene diisocyanate, and aliphatic diisocyanate compounds such as 1,6-hexamethylene diisocyanate, in alone or in a mixture of two or more. Dihydroxy compound in both ends of polyurethane comprise polyol in a form of polyester such as poly(ethyleneglycol) adipate and poly(diethyleneglycol) adipate.

Description

Manufacturing method of hot melt adhesive

The present invention relates to a method for producing a hot melt adhesive, and more particularly, to a method for producing a hot melt adhesive that can be used by directly dissolving only an adhesive without heat by introducing an isocyanate group at both ends of a polyurethane.

With the development of the industry, the demand for adhesives required for bonding between dissimilar materials is increasing. Especially, the importance of hot melt adhesives is greatly increased in terms of improving the working environment in the bonding process and reducing the manpower and automation of the working process. The hot melt adhesive has the greatest advantage as an industrial adhesive because the time elapsed after application is very short. In addition, it is a non-solvent type adhesive that is safe and harmless, has a fast adhesion speed, and can be re-adhesive. However, the main component of the hot melt adhesive currently used is a thermoplastic resin, which does not have a high adhesive strength as the thermosetting adhesive, and has a disadvantage in that it is very sensitive to the working environment such as temperature, and it is difficult to achieve both heat resistance and cold resistance. In particular, the presence of water in the bonding process is generally a deterrent to the adhesive force, so the adherend should be dried to be used as a deterrent to energy saving or productivity improvement.

Therefore, in order to maintain low adhesive properties, it is required to develop a reactive hot melt adhesive to extend the overall application range of the hot melt adhesive and to apply the structural or semi-structural adhesive.

Accordingly, the present inventors have completed the present invention by developing a moisture-curable adhesive by introducing an isocyanate group having excellent reactivity with water at both ends of the polyurethane as a result of research efforts in consideration of the above matters.

An object of the present invention is to introduce an isocyanate group at the end of the polyurethane moisture-curable poly that can adhere to a variety of adherends such as leather, glass, aluminum, iron, wood, cotton, vinyl, polypropylene and polyethylene without using a primer It is to provide a method for producing a urethane-based hot melt adhesive.

Hereinafter, the present invention will be described in detail.

In the present invention, in the preparation of a hot melt adhesive, the diisocyanate compound is heated to 30 to 80 ° C. and melted, and then 0.33 to 1 mole ratio of the dihydroxy compound and other additives are added per mole of the diisocyanate compound to 50 to 150 ° C. It is characterized in that it is produced by polymerization for 1 to 6 hours.

The present invention will be described in more detail as follows.

The present invention relates to a method for producing a moisture-curable polyurethane-based hot melt adhesive whose adhesive strength is further increased by moisture in the air, wherein a diisocyanate compound having an isocyanate group at both ends is heated and melted at 30 to 80 ° C. A dihydroxy compound having a hydroxyl group at the end is added and heated to a temperature of 50 to 150 ° C. and then polymerized for 1 to 6 hours. In the present invention, the diisocyanate compound and the dihydroxy compound are 1: 0.33 to 1 If the molar ratio is less than 1: 0.33, there is a problem in that sufficient adhesion is not expressed due to undiisocyanate diisocyanate.

In addition, when the heating temperature of the diisocyanate compound is less than 30 ° C., there is a problem that sufficient reaction does not occur since the isocyanate is not melted. When the temperature of the diisocyanate compound is higher than 80 ° C., thermal decomposition of the diisocyanate occurs. There is a problem that the reaction does not proceed sufficiently and there is a problem that pyrolysis of the prepared adhesive occurs when it exceeds 150 ℃. In addition, if the polymerization time is less than 1 hour, a complete reaction does not occur, there is a problem in stability, and if more than 6 hours there is a problem in that yellowing phenomenon occurs by the thermal decomposition of the prepared adhesive.

Examples of the diisocyanate compound used in the present invention include aromatic diisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate and 4,4'-diphenylmethane diisocyanate. Single or two or more aliphatic diisocyanate compounds such as 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 3-isocyanate methyl 3,5,5-trimethylcyclohexyl isocyanate Can be mixed and used. Sockdan dihydroxy compounds are poly (ethylene glycol) adipates with molecular weights of 1,000 to 10,000, poly (diethylene glycol) adipates, poly (1,4-butanediol) adipates, poly (1,6-hexanediol) Adipate, poly (neopentyl glycol) adipate, poly (ethylene glycol / 1,4-butanediol) adipate, poly (diethylene glycol / ethylene glycol) adipate, poly (diethylene glycol / 1,4-butanediol) Polyester type polyols, such as an adipate, are used individually or in mixture of 2 or more types.

In addition, an additive may be added to improve various properties such as heat resistance and adhesive strength of the adhesive, wherein the additive is 0 to 5 parts by weight of a heat stabilizer, 0 to 50 parts by weight of a tackifier resin and a thermoplastic resin 0 to 100 parts by weight of the adhesive composition. -50 parts by weight, viscosity regulator and 0-15 parts by weight of interfacial adhesion promoter, 0-2 parts by weight of catalyst and 0-50 parts by weight of filler are mixed or reacted at high temperature. The heat stabilizer is used alone or in combination of two or more of the rubber, plastic antioxidants and ultraviolet absorbers, and if the added amount exceeds 5 parts by weight, the adhesive strength is lowered and expensive chemicals, so there is a problem of low economic efficiency.

Tackifying resins use resins with a melting temperature of 60 to 150 ° C, aliphatic hydrocarbon resins with 4 to 9 carbon atoms, aromatic hydrocarbon resins, rosin derivatives, guarone indene resins, alkylphenol resins, terpene resins, and hydrogenated rosin A tackifying resin such as an ester resin, an acrylic resin, a chlorinated biphenyl resin and a polyethylene wax is used alone or in combination of two or more thereof. When the usage-amount of adhesiveness provision resin exceeds 50 weight part, there exists a problem that adhesive force falls and a hardening rate becomes slow.

Thermoplastics for physical properties reinforcement include poly (styrene-isoprene-styrene) copolymer, poly (styrene-butadiene-styrene) copolymer, polyamide, polyester vinyl acetate and 5 to 45% in total and a thermal melting index of 6 to 400 Phosphorus ethylene vinyl acetate copolymer or the like may be used alone or in a mixture of two or more thereof. When the amount of the thermoplastic resin added exceeds 50 parts by weight, there is a problem in that the adhesive strength is lowered and the curing speed is slowed.

In addition, a capping agent and a reactive monomer may be used in the range of 0 to 15 parts by weight for the purpose of controlling viscosity and increasing interfacial adhesion. The capping agent used may be methyldichlorosilane, methyltriethoxysilane, hexamethyldisilazane. Tert-butylchlorodimethylsilane, vinyl tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-mercapto Propyltrimethoxysilane and the like, and reactive monomers include acrylonitrile, methacrylonitrile, 2-hydroxyethyl methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, epiglohydrin, and methyl methacrylate. Rate, maleic anhydride, methyl acrylate, etc., when the amount of the viscosity modifier and the interfacial adhesion promoter is more than 15 parts by weight, the viscosity is lowered and the adhesion is also lowered. I can.

In addition, in order to accelerate the urethanation reaction, the catalyst is used within the range of 0 to 2 parts by weight, and the catalyst used is dibutyltin dilaurate, stenosoctoate, tetrabutyl titanate, etc. If it is used in excess of parts by weight, the curing reaction is accelerated so quickly that there is a problem of curing during storage or storage of the prepared adhesive.

In addition, the filler is used in the range of 0 to 50 parts by weight of silicon dioxide, calcium carbonate, titanium dioxide, bentonite, zeolite, cray and magnesium carbonate alone or a mixture of two or more of them, if the amount is more than 50 parts by weight There is a problem that the adhesive strength is lowered and the curing speed is slowed.

As described above, the moisture-curable hot melt adhesive prepared by the present invention is a solid at room temperature and melts when heated to a temperature of 80 to 150 ° C., which gradually reacts with moisture in the air to gradually increase shear bond strength and peel adhesion strength up to a certain time. It is not only effective for adhesion of high water content materials but also widely used for adhesives of various adherends such as leather, glass, aluminum, iron, wood, cotton, vinyl, polypropylene or polyethylene without using primer. It can be useful.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to Examples.

Example 1

337.5 g (1.35 mol) of 4,4'-diphenylmethane diisocyanate was heated to 40 DEG C in a nitrogen atmosphere to melt 3500 g (1 mol) of poly (ethylene glycol / 1,4-butanediol) adipate having a molecular weight of 3500 Was added slowly over 3 hours. After the addition was completed, the mixture was heated to a temperature of 120 ° C. again for 4 hours and 30 minutes, and then cooled to room temperature to terminate the polymerization to prepare a moisture-curable hot melt adhesive.

Example 2

Instead of 337.5 g (1.35 mol) of 4,4'-diphenylmethane diisocyanate used in Example 1, 2,4-tolyene diisocyanate and 2,6-tolyene diisocyanate were mixed at a ratio of 80:20 Prepared in the same manner as in Example 1, except that 235 g (1.35 mol) of mixed tolyene diisocyanate was used.

Example 3

Instead of 3500 g (1 mol) of poly (ethylene glycol / 1,4-butanediol) adipate having an average molecular weight of 3500 used in Example 1, 2000 g (1 mol) of poly (ethylene glycol) adipate having an average molecular weight of 2000 was used. Except that was prepared in the same manner as in Example 1.

Example 4

3500 g of poly (ethylene glycol / diethylene glycol / 1,4-butanediol) adipate having an average molecular weight of 3500 in place of the poly (ethylene glycol / 1,4-butanediol) adipate having an average molecular weight of 3500 used in Example 1 1 mole) was prepared in the same manner as in Example 1 except for the use.

Example 5

Instead of the poly (ethylene glycol / 1,4-butanediol) adipate having an average molecular weight of 3500 used in Example 1, 2000 g (1 mol) of poly (ethylene glycol / 1,4-butanediol) adipate having an average molecular weight of 2000 Except that used, it was prepared in the same manner as in Example 1.

Example 6

Example 1 except that 275g (1.10 mol) of 4,4'-diphenylmethane diisocyanate was used instead of 337.5g (1.35 mol) of 4,4'-diphenylmethane diisocyanate It was prepared by the method.

Example 7

A moisture-curable hot melt adhesive was prepared by adding 20 parts by weight of ethylene vinyl acetate having a vinyl acetate content of 40% to 40 parts by weight of the adhesive prepared in Example 1 and 20 parts by weight of hydrogenated rosin ester as a tackifier.

Example 8

It was prepared in the same manner as in Example 7, except that 20 parts by weight of an aromatic saturated hydrocarbon-based resin was used instead of 20 parts by weight of the hydrogenated rosin ester used in Example 7.

Example 9

A moisture hardening hot melt adhesive was prepared by adding 30 parts by weight of calcium carbonate as a filler to 100 parts by weight of the adhesive prepared in Example 1.

Example 10

15 parts by weight of calcium carbonate, 2 parts by weight of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3 parts by weight of methyl methacrylate, 2,6- by 100 parts by weight of the adhesive prepared in Example 7 A moisture curable hot melt adhesive was prepared by adding 1 part by weight of bis (1,1-dimethylethyl) -4-methylphenol and 1 part by weight of dibutyltin dilaurate.

Comparative Example 1

In order to prepare an ethylene vinyl acetate-based hot melt adhesive currently used, 20 wt% of polyethylene wax and 40 wt% of natural rosin, an tackifier, were melted at 150 ° C. under nitrogen atmosphere, and then 40 wt% of ethylene vinyl acetate having a vinyl acetate content of 43%. % Was added and melted to prepare YB hot melt adhesive.

Experimental Example

Leather and cotton were used as test pieces for the peel adhesion strength test, and polymethyl methacrylate, aluminum, and iron plate were used as an adhesive for the shear bond strength test. The test piece was washed well with toluene and then dried at a temperature of 60 ° C. for 30 minutes. The adhesive was melted at a temperature of 120 ° C. and applied to the surface of the adherend, and was pressed five times in the longitudinal direction by applying a load of about 49 Newton using a hand roller and then bonded. At this time, three test pieces used in the same test were used, and the tester used a universal tensile tester 1435 of Zwick, Switzerland. The failure loads of the tester and the specimen were within 5 to 85% of the capacity. The tensile speed was 200 ± 20 mm / min in the peel strength test, and the tensile speed was 20 ± 2 mm / min in the shear bond strength test. The adhesion test was performed 3 times after 2 hours, 48 hours, and 240 hours after adhesion. The results are shown in the following Tables 1,2,3.

Shear Adhesion Strength when Polymethyl Methacrylate is Used as Substrate

TABLE 1

Shear adhesive strength when aluminum is used as the substrate

TABLE 2

Shear Adhesion Strength Test Results when Using Steel Plate as Substrate

TABLE 3

Claims (4)

In preparing a hot melt adhesive by polymerizing a hydroxy compound and a diisocyanate compound, a polyisocyanate having a molecular weight of 1,500 to 6,000 corresponding to a molar ratio of 0.5 to 1 per mole of the diisocyanate compound after melting by heating the diisocyanate compound to 30 to 80 ° C (Diol) A method for producing a hot melt adhesive, characterized in that it is polymerized by adding adipate and other additives for 1 to 6 hours at a temperature of 50 to 150 ° C. The method of claim 1, wherein the poly (diol) adipate is a poly (ethylene glycol) adipate, poly (diethylene glycol) adipate, poly (1, 4- butanediol) adipate, poly (1, 6- hexanediol Adipate, poly (neopentyl glycol) adipate, poly (ethylene glycol / 1,4-butanediol) adipate, poly (diethylene glycol / 1,4-butanediol) adipate, poly (ethylene glycol / diethylene glycol A method for producing a hot melt adhesive, characterized in that the adipate is used alone or in combination of two or more. The diisocyanate compound according to claim 1, wherein the diisocyanate compound is an aromatic diisocyanate of 2,4-tolien diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate. Isocyanate compounds and aliphatic diisocyanate compounds of 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 3-isocyanatemethyl 3,5,5-trimethylcyclohexyl isocyanate alone or two or more Hot melt adhesive manufacturing method characterized in that used by mixing. According to claim 1, The other additives 0 to 5 parts by weight of the heat stabilizer, 0 to 50 parts by weight of the tackifier resin, 0 to 50 parts by weight of the thermoplastic resin, 0 to 15 parts by weight of the viscosity modifier and interfacial adhesion promoter. 0.24 parts by weight of catalyst or 0-50 parts by weight of filler is used.