JP5460992B2 - Reactive hot melt adhesive - Google Patents

Description

  The present invention relates to a reactive hot melt adhesive excellent in workability, capable of shifting an adherend after bonding while maintaining an initial adhesive force that is a feature of the reactive hot melt adhesive.

  Reactive hot-melt adhesives have both the initial adhesive strength of hot-melt adhesives and the final adhesive strength of reactive-curing adhesives, and can be used in various fields because they can greatly improve productivity. ing. On the other hand, due to the high initial adhesive force, when a deviation occurs during the bonding of the adherends, it is difficult to correct the deviation, and there is a problem that the yield decreases and the workability decreases. .

  Patent Document 1 discloses the prevention of lifting and peeling of a distorted adherend, particularly the time for curing until the adherend is lifted and peeled off in the summer working environment (at 35 ° C atmosphere) and the adhesive is cut. Reactive hot melt adhesives that can be significantly shortened are disclosed. Although attempts have been made to further improve the initial adhesive force in this document, the adherend could not be shifted after bonding.

Patent Document 2 discloses a moisture-curing hot melt adhesive that suppresses the development of peel strength immediately after bonding and allows the base material to be reused by separating the decorative sheet and the base material when a defective product occurs. Is disclosed. Although the decorative sheet and the base material can be peeled apart and reused by this adhesive, it is necessary to perform the adhesion again, and the adherend cannot be shifted and corrected to the correct position. Thus, in the conventional reactive hot melt adhesive, there is no idea of shifting the adherend after bonding, and an adhesive capable of correcting the shift has been demanded.
JP 2005-314445 A JP 2008-94960

  An object of the present invention is to provide a reactive hot melt adhesive excellent in workability, capable of shifting the adherend after bonding while maintaining the initial adhesive force that is a feature of the reactive hot melt adhesive It is to be.

The present invention comprises a polyol mixture having a molecular weight containing 50 to 200 parts by weight liquid polyol with respect to 3000 or less of the crystalline polyester polyol 100 parts by weight of an isocyanate-terminated urethane prepolymer obtained by reacting a polyisocyanate A reactive hot melt adhesive comprising a liquid polyester polyol and a polyether polyol as the liquid polyol .

  The reactive hot melt adhesive of the present invention can shift the adherend after bonding while maintaining the initial adhesive strength that is a feature of the reactive hot melt adhesive. Therefore, even if a deviation occurs when the adherends are bonded together, the adherend can be shifted to a correct position with a small force, so that the yield and workability can be improved.

  The polyol constituting the urethane prepolymer contained in the reactive hot melt adhesive of the present invention contains a crystalline polyester polyol having a molecular weight of 3000 or less and a liquid polyol, and 100 parts by weight of a crystalline polyester polyol having a molecular weight of 3000 or less. The liquid polyol contains 50 to 200 parts by weight. In addition, the polyol constituting the urethane prepolymer may contain a polyol other than a crystalline polyester polyol having a molecular weight of 3000 or less and a liquid polyol.

  The dicarboxylic acid constituting the crystalline polyester polyol is preferably adipic acid, sebacic acid, terephthalic acid, dodecanedioic acid or the like, and the diol is preferably ethylene glycol, butanediol, hexanediol or the like. When only a crystalline polyester polyol having a molecular weight exceeding 3000 is used, the initial adhesive strength becomes too high and the adherend cannot be displaced. It is possible to use a crystalline polyester polyol having a molecular weight of 3000 or less and a crystalline polyester polyol having a molecular weight of more than 3000 in combination.

  Examples of the liquid polyol include liquid polyester polyol and polyether polyol. The dicarboxylic acid constituting the liquid polyester polyol is preferably adipic acid, sebacic acid, isophthalic acid, terephthalic acid, phthalic anhydride, etc., and the diol is ethylene glycol, pentanediol, hexanediol, neopentyl glycol, 2-methyl-1 1,3-propanediol, cyclohexanedimethanol, 2,4-dimethyl-1,5-pentanediol polypropylene glycol and the like are preferable.

  Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random copolymers and block copolymers thereof. Workability can be improved by using a liquid polyester polyol and a polyether polyol in combination as the liquid polyol.

  Examples of the polyvalent isocyanate compound used for the reaction with the polyol to synthesize a urethane prepolymer include 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 4,4′-diphenylmethane diisocyanate (4,4 ′). -MDI), aromatic polyisocyanates such as tolylene diisocyanate and naphthalene diisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate can also be used. -MDI and its carbodiimide modified carbodiimide modified MDI are preferably used.

  The equivalent ratio NCO / OH of the isocyanate group contained in the polyisocyanate and the hydroxyl group contained in the polyol is preferably 1.5 to 2.8. If the NCO / OH is less than 1.5, the viscosity of the urethane prepolymer to be produced increases when melted, and the stability of the viscosity also deteriorates. As a moisture-curable reactive hot melt adhesive, When used, workability is reduced. When NCO / OH exceeds 2.8, a large amount of unreacted polyisocyanate monomer remains in the moisture-curable reactive hot melt adhesive, and when used in a hot roll coater, the polyisocyanate monomer is vaporized. As a result, a large amount of air diffuses into the air, resulting in problems in working environment sanitation.

  In addition to the urethane prepolymer obtained by reacting the above polyol and polyisocyanate, the moisture curable reactive hot melt adhesive in the present invention can be added with a tackifier resin, a catalyst, or the like, if necessary. . Examples of tackifying resins include styrene resins, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, and rosin esters. Examples of the catalyst include tertiary amine and tin-based catalysts. As other additives, nucleating agents such as paraffin wax and microcrystalline wax, coloring agents, anti-aging agents and the like can be added.

  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
HS 2H-201AP (product name) manufactured by Toyokuni Seiyaku Co., Ltd., which is a crystalline polyester polyol having a molecular weight of 2000, and 50 parts by weight HS 2E-581A (product name manufactured by Toyokuni Seiyaku Co., Ltd.), which is a liquid polyester polyol as a liquid polyol. , PR3007 (trade name, manufactured by ADEKA) as a polyether polyol as liquid polyol, 20 parts by weight of ester gum HD (trade name, manufactured by Arakawa Chemical Co., Ltd.) as a tackifier resin, and JEFFCAT DMDEE (as an amine catalyst) Mitsui Chemicals Fine Co., Ltd., trade name) 0.1 part by weight was placed in a separable flask equipped with a stirrer, temperature controller, and vacuum pump and stirred at 100 ° C. under reduced pressure for 2 hours for dehydration. Next, 48 parts by weight (NCO / OH = 2.5) of Millionate MT (4,4′-MDI, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to the system, and the mixture was stirred for 2 hours at 100 ° C. in a nitrogen atmosphere. The reactive hot melt adhesive of Example 1 that was solid at room temperature was obtained.

Examples 2, 3 and Comparative Examples 1-3
In addition to the polyol used in Example 1, HS 2H-451A (trade name) manufactured by Toyokuni Oil Co., Ltd., which is a crystalline polyester polyol having a molecular weight of 4500, and CAPA 6500 (product manufactured by Nippon Solvay, Inc., a product manufactured by Toyokuni Seiyaku Co., Ltd.). Name), the polyol composition and the addition amount of the amine-based catalyst were changed as shown in Table 1 using HS polyol 1000 (product name, manufactured by Toyokuni Oil Co., Ltd.), which is an amorphous polyester polyol. Each reactive hot melt adhesive was obtained in the same manner as in Example 1 except that the blending amount of Millionate MT was changed so that the value described in 1 was obtained. Each reactive hot melt adhesive was evaluated by the following method.

Initial adhesive strength Using a hot roll coater with a roll temperature set at 120 ° C., each reactive hot melt adhesive was applied to a particle board (100 mm × 90 mm, 15 mm thickness) at 80 g / m ^2, and a stainless steel plate (100 mm × 100 mm, 0.6 mm thick). Further, an 80 g / m ² adhesive was similarly applied to the back surface of the particle board, and a stainless steel plate (100 mm × 100 mm, 0.6 mm thickness) was bonded thereto. After the stainless steel plates were bonded to both sides, they were immediately clamped with a pressure of 0.098 N / mm ² for 15 minutes, and the stainless steel plates were forcibly peeled off immediately after the pressure was released. The case where the material of the particle board was broken was indicated by ○, and the case where the adhesive was agglomerated or the interface was peeled was indicated by ×.

Displaceability Prepare a large stainless steel plate and apply 80 g / m ^{2 of} each reactive hot melt adhesive to a particle board (100 mm x 100 mm, 15 mm thickness) using a hot roll coater with a roll temperature set at 120 ° C. Then, they were laminated so as to be stacked on a stainless steel plate, and a 5 kg weight was put on the particle board for 5 seconds and bonded. After 1 minute, the particle board was hooked and pulled horizontally using a digital force gauge to measure the shear bond strength.

  Each reactive hot melt adhesive of the example was excellent in the initial adhesive force, and the adherend could be displaced with a small force after bonding. On the other hand, each reactive hot melt adhesive of the comparative example was inferior in the initial adhesive force, or the adherend could not be displaced with a small force after bonding.

Claims (1)

Contains a polyol mixture containing a liquid polyol 50-200 parts by weight of at least molecular weight with respect to 3000 or less of the crystalline polyester polyol 100 parts by weight of an isocyanate-terminated urethane prepolymer obtained by reacting a polyisocyanate, the liquid A reactive hot melt adhesive comprising liquid polyester polyol and polyether polyol as a polyol .