JP3406016B2 - Reactive hot melt adhesive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-curable reactive hot-melt adhesive containing a polyester-based urethane prepolymer as a main component, and more particularly to an improvement in solidification rate. A reactive hot melt adhesive based on crystalline polyester diol. [0002] Conventionally, a moisture-curable reactive hot melt adhesive mainly comprises a urethane prepolymer having an isocyanate group at a terminal obtained by reacting a crystalline polyester diol with a diisocyanate compound as a main component. The reactive hot-melt adhesive that is used can improve the initial adhesive strength by utilizing its crystallinity, and can also improve the workability because it is non-tacky. For example, Japanese Patent Application Laid-Open No. 62-181375 discloses a mixed polyester of a polyester diol obtained from a glycol having 2 to 4 carbon atoms and a dicarboxylic acid and a polyester diol obtained from a glycol having 5 to 10 carbon atoms and a dicarboxylic acid. A reactive hot-melt adhesive comprising a urethane prepolymer obtained by reacting a diol with a diisocyanate compound is disclosed. Japanese Patent Application Laid-Open No. 88686/1987 discloses a reaction between a linear aliphatic polyester diol and a polyisocyanate. A reactive hot-melt adhesive containing a urethane prepolymer obtained as a main component is disclosed. Each of them has a feature that the time from application and bonding in the normal state of heating and melting to cooling and solidification in the initial stage to develop adhesive strength is very short. Thus, a reactive hot-melt adhesive with a further improved solidification rate has been studied. On the other hand, wax is added to a hot-melt type adhesive mainly composed of a low-polarity block copolymer rubber such as ethylene-vinyl acetate copolymer and styrene-isoprene-styrene to improve the solidification rate. It is commonly used. [0005] However, since the wax used usually has low polarity, it is poorly compatible with the urethane prepolymer having a highly polar polyester as a main chain. For this reason, when a wax is used for a reactive hot melt adhesive mainly containing a urethane prepolymer having a polyester having a high polarity as a main chain, there is a problem that phase separation is easily caused at the time of heating and melting. The present invention is intended to solve the above problems, and an object thereof is to improve the solidification rate by using a wax, and to use a hot-melt type mainly composed of a urethane prepolymer having a polyester of high polarity as a main chain. It is to provide an adhesive. The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the terminal isocyanate obtained by reacting one or more crystalline polyester diols with a polyisocyanate compound is obtained. In the urethane prepolymer having a group, a wax having a functional group capable of reacting with an isocyanate group in a molecule is provided so that the ratio of the functional group capable of reacting with the isocyanate group to the isocyanate group is 0.01 to 0.7. It has been found that the solidification rate is dramatically improved without causing phase separation between the wax and the polymer by using a compound obtained by the reaction as a main component, thereby completing the present invention. The crystalline polyester diol used in the present invention is a reaction product of one or more linear aliphatic dicarboxylic acids and one or more linear aliphatic diols. The above-mentioned linear aliphatic dicarboxylic acids include:
Adipic acid, pimelic acid, suberic acid, azelaic acid,
Sebacic acid, nonamethylene dicarboxylic acid, decamethylene dicarboxylic acid, undecamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, and the like. The linear aliphatic diols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 -Octanediol, 1,9-nonanediol, 1,10-
Decanediol and the like. These aliphatic diols can be obtained alone or in combination of two or more. The polyisocyanate compounds used in the present invention include, for example, tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), 1,4 - phenylene diisocyanate (PPDI), tetramethyl xylene diisocyanate (TMXDI), 4,4'-dicyclohexylmethane diisocyanate (H ₁₂ MDI), cyclohexane diisocyanate (CHDI), 1,6-
Hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), p-phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,5-octylene diisocyanate, modified products thereof, and the like, each of which may be used alone,
Some are used together. The reactive hot melt adhesive of the present invention uses a wax having a functional group capable of reacting with an isocyanate group in the molecule. Examples of the functional group capable of reacting with the isocyanate group include a hydroxyl group, an amino group, a mercapto group, a carboxyl, an amide group, and among others, a hydroxyl group is preferred in terms of reactivity with an isocyanate group, availability, and odor. preferable. The number of functional groups in the molecule is not particularly limited, but is preferably one or two. In the case of three or more, gelation is easily caused by crosslinking. As the wax having a hydroxyl group in the molecule as a functional group capable of reacting with an isocyanate group, an oxidized wax obtained by oxidizing and reducing a commonly used wax, an alcohol wax, and the like can be used. These waxes do not necessarily have to have hydroxyl groups in all molecules, but are preferably waxes containing at least 40 mol% or more hydroxyl groups from the viewpoint of compatibility. In the present invention, the ratio of the functional group capable of reacting with the isocyanate group to the isocyanate group of the urethane prepolymer having a terminal isocyanate group and the wax having a functional group capable of reacting with the isocyanate group in the molecule is 0. 0.01 to 0.7. When the ratio of the functional group capable of reacting with the isocyanate group to the isocyanate group is smaller than 0.01, the effect of improving the solidification rate is not obtained. When the ratio of the functional group capable of reacting with the isocyanate group to the isocyanate group is larger than 0.7, the adhesive strength of the reactive hot melt adhesive decreases. The procedure for obtaining the reactive hot melt adhesive of the present invention is to react a polyester diol with a polyisocyanate compound to obtain a urethane prepolymer, and then react a wax to obtain a desired compound. The desired compound can also be obtained by first reacting the polyisocyanate compound with the wax and then reacting the polyester diol. The reactive hot-melt adhesive of the present invention contains a compound obtained by reacting a urethane prepolymer obtained from a crystalline polyester diol with a wax as a main component. A urethane prepolymer obtained from polyether diol or polyolefin diol, a thermoplastic elastomer, a tackifier resin, a plasticizer, a catalyst, a filler, a dye, a pigment, and the like may be added. Since the wax contained in the reactive hot melt adhesive of the present invention has a functional group capable of reacting with an isocyanate group in the molecule, a urethane prepolymer having a highly polar polyester as a main chain is used. It reacts with the isocyanate group of the polymer to become the same molecule, and the compatibility is improved. Therefore, the solidification rate of the hot-melt adhesive containing a urethane prepolymer having a polyester of high polarity as a main chain as a main component can be improved by using wax. EXAMPLES Examples and comparative examples of the present invention will be described below. Example 1 1000 g of polyhexamethylene adipate (molecular weight 2500, hydroxyl value 42) and 193 g of diphenylmethane diisocyanate (Isonate 125M, manufactured by Mitsubishi Kasei Dow Co., Ltd.) were reacted at 100 ° C. for 3 hours under a nitrogen stream to contain NCO. An amount of about 4% urethane prepolymer was obtained. To this urethane prepolymer, an alcohol wax as a hydroxyl group-containing wax (Unilin alcohol # 425, hydroxyl value 105, Toyo Petrolite Co., Ltd.)
155 g) was added so that the ratio of the hydroxyl group of the wax to the isocyanate group of the urethane prepolymer was 0.2, and the mixture was further reacted for 2 hours to obtain a reactive hot melt adhesive. The compatibility and the solidification rate of this reactive hot melt adhesive were measured, and the evaluation results are shown in Table 1. Compatibility The obtained reactive hot-melt adhesive is heated and melted, poured into a glass bottle, placed in an oven at 120 ° C. for 8 hours without a lid, and then taken out. The presence or absence of separation of the components was visually observed. Solidification rate (solidification time) The obtained reactive hot-melt adhesive was heated and melted at 120 ° C., and about 0.15 g of a 50 mm wide cardboard was applied.
Immediately, another cardboard having a width of 50 mm was press-bonded with a load of 2 kg, and a load of 400 g was applied to one of the cardboards, and the cardboard was held so that a peeling force was applied to the bonded portion. 400g
The time required for pressure bonding until the film no longer peels or falls even when a load is applied is defined as a solidification time. Comparative Example 1 A reactive hot melt adhesive was obtained in the same manner as in Example 1 except that the alcohol wax was not reacted. The compatibility and the solidification rate of this reactive hot melt adhesive were measured, and the evaluation results are shown in Table 1. Comparative Example 2 1000 g of polyhexamethylene adipate (molecular weight 2500, hydroxyl value 42) and 193 g of diphenylmethane diisocyanate (Isonate 125M, manufactured by Mitsubishi Kasei Dow Co., Ltd.) were reacted at 100 ° C. for 3 hours in a nitrogen stream. And a urethane prepolymer having an NCO content of about 4%. To this urethane prepolymer, 13 g of paraffin wax (HNP-9) is added as a wax having no functional group capable of reacting with an isocyanate group in the molecule, and the mixture is stirred and mixed at 120 ° C. to form a reactive hot melt adhesive. Obtained. The compatibility and the solidification rate of this reactive hot melt adhesive were measured, and the evaluation results are shown in Table 1. [Table 1] According to the adhesive of the present invention, the solidification rate of a reactive hot-melt type adhesive which is mainly composed of a urethane prepolymer of a crystalline polyester diol having a low solidification rate is conventionally determined by using a wax. Can be improved.

Continuation of the front page (56) References JP-A-3-172380 (JP, A) JP-A-64-29481 (JP, A) JP-A-61-275324 (JP, A) JP-A-2-88686 (JP) JP-A-62-181375 (JP, A) JP-A-4-226582 (JP, A) JP-A-48-64128 (JP, A) JP-A-5-25454 (JP, A) 2-212576 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09J 4/00-201/10

Claims (1)

(57) [Claim 1] One or two crystalline polyester diols
A wax having a functional group capable of reacting with an isocyanate group in the molecule is added to a urethane prepolymer having an isocyanate group at a terminal obtained by reacting a polyisocyanate compound with a seed or more, based on the number of the isocyanate groups. A reactive hot-melt adhesive comprising a compound obtained by reacting the isocyanate group with a functional group capable of reacting with the isocyanate group in a ratio of 0.01 to 0.7 .