JP2010235767A - Moisture-curable reactive hot-melt adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moisture-curable reactive hot melt adhesive which is applicable at about 80°C, is less in the scattering of an isocyanate compound, and is excellent in adhesion performance. <P>SOLUTION: The moisture-curable type reactive hot melt adhesive includes an isocyanate-terminated urethane prepolymer, obtained by reacting a polyol composition (A) containing at least an amorphous polyester polyol (a1), a liquid polyester polyol (a2) and a polypropylene glycol (a3), and a polyfunctional isocyanate compound (B), and is characterized in that the melt viscosity at 80°C is 1,000-30,000 Pa s. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a moisture curable reactive hot melt adhesive that can be applied at low 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. On the other hand, since the hot melt adhesive contains a thermoplastic resin as a component, the final adhesive performance such as heat resistance is not sufficient. Accordingly, a hot-melt adhesive having chemical reactivity has been developed, and in addition to the advantages of the hot-melt adhesive, it has been adopted in applications requiring durability because of its excellent final adhesion performance.

  Among reactive hot melts, moisture-curable reactive hot melt adhesives containing urethane prepolymers are widely used, but because they contain isocyanate compounds, the isocyanate compounds are scattered during heating and melting, and ventilation. Equipment and masks must be worn.

Patent Document 1 discloses a reactive hot melt adhesive that can be melt-coated at 95 ° C. to 130 ° C., but cannot be used in a temperature range of about 80 ° C. Patent Document 2 discloses a reactive hot melt adhesive composition that can be applied at a low temperature (for example, 80 to 130 ° C.), but uses a urethane prepolymer and a thermoplastic resin in combination, and finally adheres. The performance was not enough. Patent Document 3 discloses a hot-melt adhesive for easily bonding an adhesive body to an adherend such as a cloth having water repellency at a low temperature, but a strength sufficient to bond a marking sheet is obtained. However, the adhesive strength required for bonding the structural material could not be obtained. Patent Document 4 discloses a reactive hot melt adhesive composition that can be applied at a relatively low temperature, but cannot be used in a temperature range of about 80 ° C. Patent Document 5 discloses a reactive hot-melt adhesive composition that can suppress the increase in melt viscosity at a temperature lower than 100 ° C. and widen the usable temperature range. However, sufficient adhesive performance is obtained depending on the application. I couldn't.
JP-A-6-93244 JP-A-6-122860 Japanese Patent Laid-Open No. 10-237412 Japanese Patent Laid-Open No. 11-71565 JP 2007-211150 A

  An object of the present invention is to provide a moisture curable reactive hot melt adhesive that can be applied at about 80 ° C., has little scattering of an isocyanate compound, and has excellent adhesion performance.

  The present invention provides an isocyanate obtained by reacting a polyol composition (A) containing at least an amorphous polyester polyol (a1), a liquid polyester polyol (a2), and a polypropylene glycol (a3) with a polyfunctional isocyanate compound (B). A moisture-curable reactive hot melt adhesive containing a terminal urethane prepolymer and having a melt viscosity at 80 ° C. of 1000 to 30000 mPa · s.

  Since the moisture-curable hot melt adhesive of the present invention can be applied at a low temperature of about 80 ° C., there is little scattering of the isocyanate compound. Moreover, since application | coating is possible at low temperature, it can be used also with respect to a base material with low heat resistance, and the life in a heat-melting state is long. Furthermore, since it has excellent adhesive performance, it can be used for various adhesive applications.

It is the perspective view which showed the split test.

  The moisture-curable reactive hot melt adhesive of the present invention contains an isocyanate-terminated urethane prepolymer obtained by reacting a polyol composition (A) with a polyfunctional isocyanate compound (B). The polyol composition (A) contains at least an amorphous polyester polyol (a1), a liquid polyester polyol (a2), and polypropylene glycol (a3). The amorphous polyester polyol (a1) and the liquid polyester polyol (a2) are mainly composed of a dicarboxylic acid and a diol.

  Amorphous polyester polyol (a1) 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 (a1) include adipic acid, phthalic anhydride, isophthalic acid, and terephthalic acid. Examples of the diol include neopentyl glycol, ethylene glycol, propylene glycol, and hexanediol. It is done.

  The liquid polyester polyol (a2) is a polyester polyol that is liquid at room temperature. Examples of the dicarboxylic acid constituting the liquid polyester polyol (a2) include adipic acid, sebacic acid, terephthalic acid, and dodecanedioic acid. Examples of the diol include ethylene glycol, butanediol, and hexanediol.

  The polyol composition (A) contains polypropylene glycol (a3) in addition to the amorphous polyester polyol (a1) and liquid polyester polyol (a2), but may further contain other polyol components. Examples thereof include crystalline polyester polyols that are solid at room temperature and castor oil-based polyols.

  In order to obtain an isocyanate-terminated urethane prepolymer, 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 4,4 ′ is used as the polyvalent isocyanate compound (B) used in the reaction with the polyol composition (A). -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 addition to the isocyanate-terminated urethane prepolymer, the moisture-curable reactive hot-melt adhesive in the present invention may contain a tackifier resin, a catalyst, a nucleating agent, a colorant, an anti-aging agent, etc. as necessary. it can. 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 type and tin type catalysts. Examples of the nucleating agent include paraffin wax and microcrystalline wax. In order to improve the curability at a low temperature, it is effective to add a catalyst or a nucleating agent.

  The moisture curable reactive hot melt adhesive of the present invention has an 80 ° C. melt viscosity (10 rpm value) of 1000 to 30000 mPa · s. If it is less than 1000 mPa · s, it is not preferable because suction or dripping occurs on the adherend during application, and if it exceeds 30000 mPa · s, application to the adherend becomes difficult. A more preferable 80 degreeC melt viscosity is 1000-20000 mPa * s, More preferably, it is 1000-15000 mPa * s. The 80 ° C. melt viscosity of the moisture curable reactive hot melt adhesive is affected by the molecular weight of the polyol composition, and in particular by the molecular weight of polypropylene glycol. By adjusting the molecular weight of the polypropylene glycol used, the 80 ° C. melt viscosity can be easily adjusted.

  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.

  The polyol used for the Example and the comparative example used the commercial item which has the property described in Table 1. For example, polyester polyol 1 has a molecular weight of 1000, phthalic anhydride as a constituent component as a dicarboxylic acid, neopentyl glycol as a constituent component as a diol, is amorphous, and corresponds to the present application (a1). .

Manufacture of moisture-curable reactive hot melt adhesive 100 parts by weight of polyester polyol 1, 100 parts by weight of polyester polyol 2, 30 parts by weight of polypropylene glycol 1, ester HD which is a hydrogenated rosin ester (trade name, manufactured by Arakawa Chemical Industries, Ltd.) 20 parts by weight was placed in a separable flask equipped with a stirrer, a temperature controller, and a vacuum pump, and stirred at 120 ° C. under reduced pressure for 2 hours for dehydration. Next, 177 parts by weight of Millionate MT (4, 4′-MDI, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name) was added as a polyfunctional isocyanate compound (NCO / OH = 2.0), and 2 at 100 ° C. under a nitrogen atmosphere. The reaction was conducted by stirring for a time to obtain a moisture-curable reactive hot melt adhesive that was solid at room temperature. Moreover, it manufactured similarly to Example 1 by the mixing | blending of Table 2, and obtained each moisture hardening type reactive hot-melt-adhesive. Each moisture curing type reactive hot melt adhesive was evaluated as follows.

Viscosity Viscosity (10 rpm value) at 80 ° C., 100 ° C., and 120 ° C. was measured using RVD V-1 + (trade name) manufactured by Brookfield.
Each moisture curable reactive hot melt adhesive melted at 90 ° C. was applied to an initial strength paper honeycomb core (100 mm × 100 mm, thickness 30 mm) (application amount 50 g / mm ² per side) for 1 minute in a 23 ° C. atmosphere. Alternatively, after leaving for 5 minutes, an insulation board (110 mm × 100 mm, thickness 10 mm) was bonded to both surfaces, and immediately pressed with 0.1 MPa for 10 seconds, and then immediately subjected to a split test to measure strength (FIG. 1). reference).

  As shown in Table 2, excellent adhesive performance was obtained in Example 1, but in Comparative Examples 1 and 2, the adhesive performance was inferior. Further, Comparative Example 3 had a high melt viscosity at 80 ° C. and was difficult to use.

  Next, about the moisture hardening type reactive hot-melt-adhesive of Example 1, the amount of scattering of the isocyanate compound was evaluated. Specifically, after the moisture-curing reactive hot melt adhesive of Example 1 was put into a hot roll coater set at 80 ° C. and confirmed to be completely melted, the space immediately above the hot roll coater When 5 L of air was sucked into a filter holding 2-pyridylpiperazine and the amount of MDI derivatized using liquid chromatography (HPLC) was measured, the concentration of the isocyanate compound was 110 ppb. When the same test was performed with the hot roll coater set at 120 ° C., the concentration of the isocyanate compound was 2900 ppb. Therefore, the use of a moisture-curing hot melt adhesive that can be applied even at low temperatures can greatly suppress the scattering of the isocyanate compound.

  Since the moisture-curable hot melt adhesive of the present invention can be applied at a low temperature of about 80 ° C., there is little scattering of the isocyanate compound. Moreover, since application | coating is possible at low temperature, it can be used also with respect to a base material with low heat resistance, and the life in a heat-melting state is long. Furthermore, since it has excellent adhesive performance, it can be used for various adhesive applications.

1 Paper honeycomb core 2 Insulation board

Claims (1)

  Isocyanate-terminated urethane prepolymer obtained by reacting a polyfunctional isocyanate compound (B) with a polyol composition (A) containing at least an amorphous polyester polyol (a1), a liquid polyester polyol (a2), and a polypropylene glycol (a3). A moisture-curable reactive hot-melt adhesive having a melt viscosity of 1000 to 30000 mPa · s at 80 ° C.

Images