JP2012214613A - Moisture-curable reactive hot melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture-curable reactive hot melt adhesive having a long tack free time, and capable of imparting excellent initial tack at high temperatures.SOLUTION: The moisture-curable reactive hot melt adhesive is characterized by comprising an isocyanate-terminated urethane prepolymer obtained by reacting a polyol composition including at least an amorphous polyester polyol and polyfunctional isocyanate compounds, a polyolefin and rosin. The preferable content of the polyolefin is 3-12 wt.% per total adhesive.

Description

  The present invention relates to a moisture-curable reactive hot-melt adhesive that has a long tack-free time and can provide excellent initial adhesion performance even at high temperatures.

  Hot melt adhesives are excellent in work environment and productivity because they do not contain a solvent and are excellent in initial adhesive strength, and are used in various fields. In addition, reactive hot melt adhesives having both reactive curability are excellent not only in excellent initial adhesive strength but also in final adhesive strength after curing reaction, and are used in fields where heat resistance is required.

  On the other hand, the problem with reactive hot melt adhesives is that if you try to improve the initial adhesive strength, the tack-free time will be shortened and workability will be reduced, and if you try to increase the tack-free time in order to ensure workability, The point that adhesive force falls is mentioned. In particular, in the summer when the ambient temperature becomes high, the initial adhesive force tends to decrease.

Patent Document 1 discloses a reactive hot-melt adhesive whose main object is to maintain the length of time during which adhesion is possible after application and to improve the resin strength after solidification. However, the initial adhesive strength when the ambient temperature is high has not been sufficiently studied.
JP 2004-307658 A

  In order to solve this problem, attempts have been made to increase the initial adhesive force by promoting the cooling of the adhesive by pressing with a cold press cooled to room temperature or lower. However, when a cold press cooled to room temperature or lower is used, there is a problem that rust is generated due to condensation of the metal pressing plate. Therefore, there is a demand for an adhesive that can exhibit a high initial adhesive force without significantly reducing the temperature of the cold press.

  An object of the present invention is to provide a moisture-curable reactive hot melt adhesive that has a long tack-free time and can provide excellent initial adhesion performance even at high temperatures.

  The present invention comprises a moisture-curing reactive property comprising an isocyanate-terminated urethane prepolymer obtained by reacting a polyol composition containing at least an amorphous polyester polyol with a polyfunctional isocyanate compound, a polyolefin and a rosin. Hot melt adhesive.

  The moisture-curable reactive hot melt adhesive of the present invention has a long tack-free time and excellent initial adhesive performance even at high temperatures. Therefore, excellent initial adhesion performance can be obtained without excessively reducing the temperature of the cold press used for pressing, and rust is not generated on the metal pressing plate.

  The moisture curable reactive hot melt adhesive of the present invention contains an isocyanate-terminated urethane prepolymer obtained by reacting at least a polyol composition containing an amorphous polyester polyol and a polyfunctional isocyanate compound.

Amorphous polyester polyol is a polyester polyol having no clear crystal structure by X-ray diffraction and having only a glass transition temperature. Examples of the dicarboxylic acid constituting the amorphous polyester polyol include adipic acid, phthalic anhydride, isophthalic acid, and terephthalic acid. Examples of the diol include neopentyl glycol, ethylene glycol, propylene glycol, and hexane diol.
It is preferable to use 20 to 50% by weight of amorphous polyester polyol with respect to the entire polyol composition. By containing the amorphous polyester polyol in this range, the initial adhesive force is hardly lowered even at high temperatures.

  Examples of polyols other than amorphous polyester polyol include crystalline polyester polyol, liquid polyester polyol, polyether polyol, polycarbonate polyol, and polycaprolactone.

  The crystalline polyester polyol is a polyester polyol having a clear crystal structure confirmed by X-ray diffraction and having a glass transition point and a melting point. Examples of the dicarboxylic acid constituting the crystalline polyester polyol include adipic acid, sebacic acid, terephthalic acid, and dodecanedioic acid. Examples of the diol include ethylene glycol, butanediol, and hexanediol.

  The liquid polyester polyol is a polyester polyol that is liquid at room temperature. Examples of the dicarboxylic acid constituting the liquid polyester polyol include adipic acid, sebacic acid, terephthalic acid, and dodecanedioic acid. Examples of the diol include ethylene glycol, butanediol, and hexanediol.

  Examples of polycaprolactone (polyol) include, but are not limited to, poly-γ-caprolactone triol and poly-γ-caprolactone tetraol obtained by ring-opening polymerization of γ-caprolactone.

  In order to obtain an isocyanate-terminated urethane prepolymer, 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 4,4 is used as a polyvalent isocyanate compound used in the reaction with a polyol composition containing at least an amorphous polyester polyol. Examples include aromatic isocyanates such as' -diphenylmethane diisocyanate (4,4'-MDI), tolylene diisocyanate and naphthalene diisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate. Of these, 4,4'-MDI and carbodiimide-modified MDI, which is a carbodiimide-modified product thereof, are preferably used from the viewpoints of moisture curability and safety. The equivalent ratio NCO / OH of the isocyanate group contained in the polyisocyanate and the hydroxyl group contained in the polyester polyol is preferably 1.5 to 2.5. Within this range, there is no significant increase in viscosity even in the melting state for a long time in the melting apparatus, and there is little foaming due to carbon dioxide during the curing reaction. Moreover, there is little influence on the work environment by volatilization of the unreacted polyfunctional isocyanate compound.

  In the present invention, the polyolefin is used for extending the tack-free time from the adhesive strength and improving the initial adhesive strength. Examples of commercially available polyolefins include VESTOPLAST 408 and VESTOPLAST 750 (trade name, manufactured by Evonik). The polyolefin is preferably added in an amount of 1 to 15% by weight, more preferably 3 to 12% by weight, based on the total amount of the adhesive.

  Examples of the rosin include wood rosin, gum rosin, hydrogenated rosin, tall oil rosin, and polymerized rosin using these. Further, rosin esters having active hydrogen capable of reacting with isocyanate include rosin esters, which are obtained by reacting with polyol using rosins as acid components. Since it reacts with isocyanate, it is preferable to blend a rosin ester. Rosin is preferably added in an amount of 1 to 15% by weight, more preferably 3 to 12% by weight, based on the total amount of the adhesive.

The moisture-curable reactive hot melt adhesive in the present invention is a tackifying resin, if necessary.
A catalyst, a nucleating agent, a coloring agent, an anti-aging agent and the like can be added. Examples of tackifying resins include styrene resins, terpene resins, aliphatic petroleum resins, and aromatic petroleum resins. Examples of the catalyst include tertiary amine type and tin type catalysts. Examples of the nucleating agent include paraffin wax and microcrystalline wax. In order to improve curability at low temperatures, it is effective to add a catalyst or a nucleating agent.

  Hereinafter, based on an Example and a comparative example, this invention is demonstrated in detail. However, the present invention is not limited to the examples.

Example 1
Amorphous polyester polyol (molecular weight 1000, phthalic anhydride and neopentyl glycol as constituent components) 50 parts by weight, amorphous polyester polyol (molecular weight 3000, isophthalic acid, terephthalic acid, adipic acid, ethylene glycol and neopentyl glycol) 100 parts by weight), crystalline polyester polyol (molecular weight 4500, adipic acid and 1,6-hexanediol are constituents), 30 parts by weight, crystalline polyester polyol (molecular weight 2000, sebacic acid and 1, 30 parts by weight of a 6-hexanediol component, 10 parts by weight of a liquid polyester polyol (molecular weight 2000, adipic acid, neopentyl glycol and 1,6-hexanediol as constituents), a liquid polyester polyol ( 3500 molecular weight, 40 parts by weight of phthalic anhydride, terephthalic acid, adipic acid and ethylene glycol), 20 parts by weight of polypropylene glycol having a molecular weight of 3000, super ester S-100 as rosin (manufactured by Arakawa Chemical Industries) , Trade name) 30 parts by weight, polyolefin VESTOPLAST 408 (Evonik, trade name) 40 parts by weight, defoaming agent Dappo SN-351 (San Nopco, trade name) 0.5 parts by weight, amine catalyst DMDEE (Mitsui Chemical Fine Co., Ltd., trade name) 0.1 part by weight was put into a separable flask equipped with a stirrer, a temperature controller, and a vacuum pump and stirred at 125 ° C. under reduced pressure for 2 hours for dehydration. Next, 63 parts by weight of Millionate MT (4, 4′-MDI, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name) is added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and 2 at 100 ° C. in a nitrogen atmosphere. The reaction was conducted by stirring for a time to obtain the moisture-curable reactive hot melt adhesive of Example 1 that was solid at room temperature.

Example 2
Amorphous polyester polyol (molecular weight 1000, phthalic anhydride and neopentyl glycol as constituent components) 50 parts by weight, amorphous polyester polyol (molecular weight 3000, isophthalic acid, terephthalic acid, adipic acid, ethylene glycol and neopentyl glycol) 100 parts by weight), crystalline polyester polyol (molecular weight 2000, adipic acid and 1,6-hexanediol as constituents) 30 parts by weight, crystalline polyester polyol (molecular weight 2000, sebacic acid and 1, 30 parts by weight of a 6-hexanediol component, 10 parts by weight of a liquid polyester polyol (molecular weight 2000, adipic acid, neopentyl glycol and 1,6-hexanediol as constituents), a liquid polyester polyol ( Molecular weight 3000, 10 parts by weight of isophthalic acid, adipic acid, sebacic acid, neopentyl glycol, ethylene glycol and 1,6-hexanediol as constituent components, liquid polyester polyol (molecular weight 3500, phthalic anhydride, terephthalic acid, 40 parts by weight of adipic acid and ethylene glycol), 20 parts by weight of polypropylene glycol having a molecular weight of 3000, 30 parts by weight of superester S-100 as rosin, 40 parts by weight of VESTOPLAST 408 as polyolefin, and Dappo as a defoaming agent SN-351 0.5 part by weight and DMDEE 0.1 part by weight as amine catalyst were put into a separable flask equipped with a stirrer, temperature controller and vacuum pump, and stirred at 125 ° C. under reduced pressure for 2 hours for dehydration. . Next, 63 parts by weight of Millionate MT was added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and the mixture was allowed to react with stirring at 100 ° C. for 2 hours in a nitrogen atmosphere. A mold reactive hot melt adhesive was obtained.

Comparative Example 1
Amorphous polyester polyol (molecular weight 2000, ethylene glycol, neopentyl glycol, 1,6-hexanediol, propylene glycol and isophthalic acid as constituent components) 100 parts by weight, crystalline polyester polyol (molecular weight 4500, adipic acid and 1 , 6-hexanediol as a constituent) 100 parts by weight, liquid polyester polyol (molecular weight 3500, adipic acid, neopentyl glycol and 1,6-hexanediol as constituents) 90 parts by weight, molecular weight 3000 20 parts by weight of polypropylene glycol, 20 parts by weight of polycaprolactone diol having a molecular weight of 50000, 0.5 part by weight of Dappo SN-351 as a defoaming agent, 0.1 part by weight of DMDEE as an amine catalyst, a stirring device, a temperature control device, true Placed in a separable flask fitted with a pump, 125 ° C., and stirred for 2 hours under reduced pressure and dried. Next, 54 parts by weight of Millionate MT was added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and the mixture was allowed to react with stirring at 100 ° C. for 2 hours in a nitrogen atmosphere. A mold reactive hot melt adhesive was obtained.

Comparative Example 2
Amorphous polyester polyol (molecular weight 1000, phthalic anhydride and neopentyl glycol as constituent components) 50 parts by weight, amorphous polyester polyol (molecular weight 3000, isophthalic acid, terephthalic acid, adipic acid, ethylene glycol and neopentyl glycol) 100 parts by weight), crystalline polyester polyol (molecular weight 2000, adipic acid and 1,6-hexanediol as constituents) 30 parts by weight, crystalline polyester polyol (molecular weight 2000, sebacic acid and 1, 30 parts by weight of a 6-hexanediol component, 10 parts by weight of a liquid polyester polyol (molecular weight 2000, adipic acid, neopentyl glycol and 1,6-hexanediol as constituents), a liquid polyester polyol ( Molecular weight 3000, 10 parts by weight of isophthalic acid, adipic acid, sebacic acid, neopentyl glycol, ethylene glycol and 1,6-hexanediol as constituent components, liquid polyester polyol (molecular weight 3500, phthalic anhydride, terephthalic acid, 40 parts by weight of adipic acid and ethylene glycol), 20 parts by weight of polypropylene glycol having a molecular weight of 3000, 40 parts by weight of VESTOPLAST 408 as polyolefin, 0.5 part by weight of Dappo SN-351 as defoaming agent, amine catalyst As a sample, DMDEE (0.1 part by weight) was placed in a separable flask equipped with a stirrer, temperature controller, and vacuum pump, and stirred at 125 ° C. under reduced pressure for 2 hours for dehydration. Next, 63 parts by weight of Millionate MT was added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and the mixture was allowed to react with stirring at 100 ° C. for 2 hours in a nitrogen atmosphere. A mold reactive hot melt adhesive was obtained.

Comparative Example 3
Crystalline polyester polyol (molecular weight 4500, adipic acid and 1,6-hexanediol as constituent components) 30 parts by weight, crystalline polyester polyol (molecular weight 2000, sebacic acid and 1,6-hexanediol as constituent components) 30 parts by weight, crystalline polyester polyol (molecular weight 5000, comprising sebacic acid and 1,6-hexanediol), crystalline polyester polyol (molecular weight 10,000, comprising sebacic acid and 1,6-hexanediol) Component) 50 parts by weight, liquid polyester polyol (molecular weight 2000, adipic acid, neopentyl glycol and 1,6-hexanediol as constituents) 10 parts by weight, liquid polyester polyol (molecular weight 3500, phthalic anhydride, terephthalic acid) Acid, horse mackerel 40 parts by weight of an acid and ethylene glycol), 20 parts by weight of polypropylene glycol having a molecular weight of 3000, 30 parts by weight of superester S-100 as rosin, 40 parts by weight of VESTOPLAST 408 as polyolefin, and Dappo as a defoaming agent SN-351 0.5 part by weight and DMDEE 0.1 part by weight as amine catalyst were put into a separable flask equipped with a stirrer, temperature controller and vacuum pump, and stirred at 125 ° C. under reduced pressure for 2 hours for dehydration. . Next, 58 parts by weight of Millionate MT was added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and the mixture was allowed to react with stirring at 100 ° C. for 2 hours in a nitrogen atmosphere. A mold reactive hot melt adhesive was obtained.

  Each moisture-curing reactive hot melt adhesive obtained was subjected to a test evaluation by the following method.

Storage Stability Each moisture curable reactive hot melt adhesive was allowed to stand in an atmosphere of 120 ° C. for 24 hours, and the properties were observed. In particular, the case where there was no abnormality was evaluated as ○, and the case where the phase was separated was evaluated as ×.

Viscosity Viscosity (10 rpm value) at 120 ° C. and 135 ° C. was measured using RVD V-1 + (trade name) manufactured by Brookfield.

Initial adhesive strength Applying 80g / m ^{2 of} each moisture-curing reactive hot melt adhesive melted at 120 ° C to the steel plate adjusted to 23 ° C using an applicator and opening for 90 seconds in an atmosphere of 23 ° C Time was taken and the olefin sheet was bonded together. Furthermore, after curing for 60 seconds in a 23 ° C. atmosphere, 90 ° peel strength was measured at a pulling speed of 300 mm / min using a push-pull gauge.
Similarly, the peel strength was measured using a steel plate adjusted to 40 ° C., taking an open time and curing in an atmosphere of 40 ° C.

  Each of the moisture-curable reactive hot melt adhesives in Examples was excellent in initial adhesive force even at a relatively high temperature. On the other hand, Comparative Example 1 containing no polyolefin had a low initial adhesive strength. Further, Comparative Example 2 containing no rosin was not practical because of poor storage stability. Furthermore, about the comparative example 3 which does not contain an amorphous polyester polyol, the initial fall of the initial adhesive force was seen large as atmospheric temperature rose.

Claims (2)

  A moisture-curable reactive hot melt adhesive comprising an isocyanate-terminated urethane prepolymer obtained by reacting a polyol composition containing at least an amorphous polyester polyol with a polyfunctional isocyanate compound, a polyolefin and a rosin .   The moisture-curable reactive hot melt adhesive according to claim 1, wherein the content of the polyolefin is 3 to 12% by weight based on the total amount of the adhesive.