JP2002180024A - Reactive hot-melt adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactive hot-melt adhesive for bookbinding, excellent in adhesive strength, high-speed workability, openability of book pages, cold and hot resistant tough coating, bookbinding processing and the like, composed to conventional adhesives for bookbinding such as thermoplastic resin-based adhesives or urethane-based reactive adhesives. SOLUTION: This reactive hot-melt adhesive composition is characteristically obtained by reaction between a polyfunctional isocyanate compound (A component), a crystalline polyester polyol (B component), an amorphous polyester polyol (C component) and a polyol having rosin skeleton (D component).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a moisture-curable reactive hot melt useful for bookbinding and the like having a curability due to a reaction with moisture having excellent performance such as high adhesive strength, high-speed workability, and stability over time. Related to melt adhesive.

[0002]

2. Description of the Related Art Generally, a hot melt adhesive for bookbinding is constituted by adding a tackifier such as rosin, terpene resin, petroleum resin to a thermoplastic resin, for example, an ethylene-vinyl acetate copolymer. I have. Thermoplastic resin
When the adhesive is used, it gives cohesive force to the adhesive, and the tackifier has a function of making the adhesive more remarkably exhibit tackiness when heated.

[0003] However, the hot melt adhesive using the above thermoplastic resin, when used for bookbinding,
Over time, the adhesive layer deteriorates and loses its strength,
It is necessary to increase the amount of adhesive to be applied in order to increase bookbinding or to increase the adhesive strength. As a result, there is a problem that book spreadability is poor. In addition, since bookbinding is performed by melting at a high temperature of 180 ° C or more, there is an economical problem. Sufficient performance in adhesive strength, cold / heat resistance, aging resistance, book spread, bonding workability, etc. Did not demonstrate.

[0004] For this purpose, moisture-curable urethane-based reactive adhesives have been proposed as an alternative to the hot-melt adhesive described above. However, these urethane-based reactive adhesives have a moisture-curing reaction adhesive. It takes a long time to solidify because of the low speed, and in the early stage of the reaction, adhesion to paper is extremely weak, and it is difficult to form a tough adhesive film. Unevenness of the book and the like appear. Thus, no high-quality bookbinding adhesive having high-speed bookbinding workability has been provided.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an adhesive strength, a high-speed workability, and a spread of a book which are higher than those of a conventional adhesive for binding using a thermoplastic resin-based hot melt adhesive or a urethane-based reactive adhesive. It is an object of the present invention to provide a reactive hot-melt adhesive for bookbinding, which is excellent in heat resistance, cold and heat resistance, tough film properties, bookbinding workability, and the like.

[0006]

The above objects are achieved by the present invention described below. That is, the present invention relates to a polyfunctional isocyanate compound (hereinafter, referred to as a component A), a crystalline polyester polyol (hereinafter, referred to as a component B), a non-crystalline polyester polyol (hereinafter, referred to as a component C),
A reactive hot melt adhesive composition characterized by reacting with a polyol having a rosin skeleton (hereinafter, referred to as a D component).

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the reactive hot-melt adhesive composition described above is more effective than a conventional adhesive for bookbinding using a urethane-based reactive hot-melt adhesive. It has also been found to be a reactive hot-melt adhesive for bookbinding with excellent adhesive strength, high-speed workability, book spreadability, tough film resistance to cold and heat, and excellent bookbinding workability.

[0008]

Next, the present invention will be described in more detail with reference to preferred embodiments. As the component A used in the present invention, a polyfunctional isocyanate monomer compound, a polymer of the polyfunctional isocyanate or various modified products, a terminal product of a reaction product of the polyfunctional isocyanate with a polyol having a relatively low molecular weight, or the like is used. A relatively low molecular weight isocyanate compound having at least two isocyanate groups.

As polyfunctional isocyanates, tolylene diisocyanate, xylylene diisocyanate, 4,4
4'-diphenylmethane diisocyanate, 4,4'-
Diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,
3′-dimethyldiphenylmethane-4,4′-diisocyanate, 4,4′-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene diisocyanate,
Aromatic diisocyanates such as 3,3'-dimethoxydiphenyl-4,4'-diisocyanate; aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate and lysine diisocyanate; isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane Alicyclic diisocyanates such as diisocyanate and norbornane diisocyanate; and mixtures thereof. Preferred diisocyanates include, for example, aromatic diisocyanates such as tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate.

Examples of the relatively low molecular weight isocyanate compound containing an isocyanate group at the terminal include dimers and trimers of the above-mentioned polyfunctional isocyanates, modified carbodiimides of polyfunctional isocyanates, polyfunctional isocyanate monomers and modified products thereof. Reaction products containing an isocyanate group at the terminal of a polymer and a low molecular weight polyol.

Examples of the low-molecular-weight polyol to be reacted with the above-mentioned polyfunctional isocyanate include propylene glycol, butanediol, ethylene glycol, glycerin, trimethylolpropane, and trimethylolethane.

The component B used in the present invention is a crystalline polyester polyol which is solid at ordinary temperature (25 ° C.) and has a melting point of 40 to 90 ° C. This crystalline polyester polyol is used for the purpose of accelerating the initial solidification of the reactive hot melt adhesive. If the melting point exceeds the above upper limit, the viscosity of the adhesive at the time of fusion bonding increases, the applicability of the obtained adhesive becomes poor, the workability decreases, and the moisture-cured adhesive layer becomes hard. However, when the melting point is less than the lower limit, the solidification rate of the obtained adhesive is reduced,
There is a problem that the initial adhesive strength of the adhesive is reduced.

The component B includes polyester polyol which is a polycondensation reaction product of glycol and a dibasic acid, caprolactone polyol which is a ring-opening polymerization product of a caprolactone monomer compound, and a mixture thereof. As the above polyester polyol,
For example, dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid and ethylene glycol, 1,3-propanediol, 1, Examples include polycondensation reaction products with glycols such as 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and 1,9-nonanediol. Examples of the caprolactone polyol include a ring-opening polymerization product of ε-caprolactone using ethylene glycol, diethylene glycol, neopentyl glycol or the like as an initiator.

The crystalline polyester polyol or caprolactone polyol as the component B has a number average molecular weight of 2,000 to 5,000, and preferably a number average molecular weight of 3
000-4500. When the number average molecular weight exceeds the above upper limit, there is a problem that the melt viscosity at the time of bonding of the obtained adhesive increases and coating workability decreases, while the number average molecular weight is less than the above lower limit. However, there is a problem in that the solidification rate of the obtained adhesive during the melt-bonding becomes slow, and the initial adhesive strength decreases.

The component C used in the present invention is an amorphous polyester polyol which is liquid at normal temperature (25 ° C.). This C component is mainly used for imparting flexibility. The above-mentioned non-crystalline polyester polyol is a liquid product at ordinary temperature among polycondensation reaction products of glycol and dibasic acid.

As the non-crystalline polyester polyol as the component C, for example, succinic acid, glutaric acid,
Dibasic acids such as adipic acid, terephthalic acid and isophthalic acid and propylene glycol, neopentyl glycol,
Polycondensation reaction products with glycols such as 3-methyl-1,5-pentanediol and diethylene glycol, and mixtures thereof.

The number average molecular weight of the non-crystalline polyester polyol as the component C is preferably from 2000 to 5
000. When the number average molecular weight exceeds the above upper limit, there is a problem that the viscosity of the obtained adhesive at the time of melting is increased and coating workability is reduced.On the other hand, when the number average molecular weight is less than the above lower limit, When the component C is reacted with the component A, the concentration of the free isocyanate group becomes too high,
There is a problem that the adhesive layer film obtained after moisture curing of the obtained adhesive becomes hard, and when used for bookbinding, the spread of books becomes poor.

The D component used in the present invention comprises a polyol and rosin or a rosin derivative (hereinafter, simply referred to as rosins).
And / or a compound having a glycidyl group in the molecule and a rosin, and a polyol having 1.8 to 2.2 rosin skeletons and hydroxyl groups on average in the molecule. These D components include crystalline materials that are solid at room temperature and amorphous materials that are liquid at room temperature. This D component is used for the purpose of improving the adhesiveness at the time of adhesion and the wettability to paper. Examples of the above rosins include wood rosin, gum rosin, hydrogenated rosin, disproportionated rosin, tall oil rosin and wood-based polymerized rosin, gum-based polymerized rosin, polymerized rosin such as tall oil-based polymerized rosin, and the like. Rosins such as a mixture are exemplified. The number average molecular weight of the D component is from 400 to 15,000, preferably 1
000-5000. These D components were obtained from Arakawa Chemical Industries, Ltd. as “KE-615-3” and “KE-60”.
1 "and" KE-622 Kai "can be used in the present invention.

The proportions of the components B, C and D are as follows: 10% to 60% by weight of the component B, 5% to 50% by weight of the component C, D
The components are from 20% to 60% by weight. When the proportion of the B component exceeds the above upper limit, there is a problem that the adhesive layer film obtained after moisture curing of the obtained adhesive becomes hard and the spread of the book becomes poor. There is a problem that the solidification speed of the agent is reduced and the adhesive strength is also reduced. When the proportion of the component C exceeds the above upper limit, the solidification rate of the obtained adhesive becomes extremely slow,
There is a problem that the initial adhesive strength is lowered, the bookbinding workability is lowered, and the adhesive strength that satisfies the quality as a product cannot be obtained. Is hard and the openability of the book is reduced. Further, when the proportion of the D component exceeds the upper limit, there is a problem that the solidification rate of the obtained adhesive is reduced, or the adhesive layer film after moisture curing of the obtained adhesive is easily hardened. If this is the case, there is a problem that the initial adhesiveness of the obtained adhesive is not sufficient and bookbinding workability is reduced.

The reactive hot melt adhesive composition of the present invention comprises the above component A polyfunctional isocyanate compound,
A mixed polyol compound comprising the component, component C and component D is blended with an isocyanate group and an equivalent ratio of hydroxyl groups in all polyols (NCO / OH ratio) in the range of 1.2 to 2.5, and the mixture is mixed under a nitrogen stream. It is obtained by reacting at a temperature of 80 to 150 ° C. for about 6 hours. If necessary, a known organometallic compound, amine compound, or the like may be added as a catalyst for the reaction. If the ratio of the NCO / OH ratio exceeds the upper limit, the amount of unreacted polyfunctional isocyanate monomer becomes excessive, and there is a problem that safety in the working environment is deteriorated. However, there is a problem that the melt viscosity of the obtained adhesive is excessively increased, so that the application operation at the time of bookbinding of the adhesive becomes difficult. The obtained adhesive composition of the present invention has a melting point of 40 to 15
0 ° C.

The reactive hot melt adhesive composition of the present invention may further contain additives such as wax, filler, plasticizer, curing reaction catalyst, antioxidant, pigment, etc. in a range which does not interfere with the object of the present invention. May be added as additives, for example, fillers such as calcium carbonate, titanium oxide, barium sulfate, talc, clay, liquid paraffin, plasticizers such as polybutene, organometallic tertiary amine compounds, etc. Examples include a curing reaction catalyst and an antioxidant such as hindered phenol. The reactive hot melt adhesive composition of the present invention is obtained by melt-kneading and homogenizing the above components, and is usually provided as a solid. The hot melt adhesive composition of the present invention has a temperature of 50 to 150 ° C., preferably 8 to 150 ° C.
Fused to 0-120 ° C, about 200-400 μm on cover
And glue it to the book using a bookbinding machine. Although the reactive hot melt adhesive composition of the present invention has been mainly described for bookbinding, the reactive hot melt adhesive composition of the present invention is not limited to bookbinding.

[0022]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the description, “parts” is based on weight. The production of these compositions is not limited to this production example. Example 1 A crystalline polyester polyol (B) which is a polycondensation reaction product of 1,6-hexanediol and sebacic acid was placed in a reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube.
Component, number average molecular weight 3500, melting point 65 ° C) 40.00
, A non-crystalline polyester polyol (C component, number average molecular weight 5000), which is a polycondensation reaction product of 3-methyl-1,5-pentanediol and adipic acid, and a rosin skeleton in the molecule. Having polyol (D component,
40.00 parts of Arakawa Chemical Industries, Ltd., KE-615-3, number average molecular weight 2000) was mixed and stirred at 100 ° C., degassed in vacuo for 45 minutes, and then 4,4′-diphenylmethane diisocyanate. 73 parts were added and reacted at a temperature of 90 ° C. for 6 hours under a nitrogen stream to give a melting point of 58 ° C.
A reactive hot melt adhesive composition of the present invention having a number average molecular weight of 7,700 was prepared.

Example 2 A crystalline polyester polyol (B), which is a polycondensation reaction product of 1,6-hexanediol and decamethylenedicarboxylic acid, was placed in a reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube. Component, number average molecular weight 3500, melting point 72
C) 40.00 parts, 20.00 parts of an amorphous polyester polyol (C component, number average molecular weight 2000) which is a polycondensation reaction product of propylene glycol and adipic acid, and a polyol having a rosin skeleton in the molecule ( D component,
40.0 parts of Arakawa Chemical Industry Co., Ltd., KE-615-3, number average molecular weight 2000) was mixed and stirred at 100 ° C., degassed in vacuo for 45 minutes, and then 4,4′-diphenylmethane diisocyanate. 46 parts were added and reacted at a temperature of 90 ° C. for 6 hours under a nitrogen stream to give a melting point of 65 ° C.
A reactive hot melt adhesive composition of the present invention having a number average molecular weight of 6,400 was prepared.

COMPARATIVE EXAMPLE 1 In a reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube, a crystalline polyester polyoh (number-average) which was a polycondensation reaction product of 1,6-hexanediol and adipic acid was used. (Molecular weight: 2,000, melting point: 55 ° C.) 100.00 parts were charged, and the mixture was degassed under vacuum at 100 ° C. for 45 minutes.
4,4'-diphenylmethane diisocyanate 18.7
7 parts were added and reacted at 90 ° C. for 6 hours under a nitrogen stream to prepare a reactive hot melt adhesive composition of Comparative Example having a melting point of 49 ° C. and a number average molecular weight of 12,000.

Comparative Example 2 A crystalline polyester polyol (number-average molecular weight), which is a polycondensation reaction product of 1,6-hexanediol and adipic acid, was placed in a reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube. 4500, melting point 63 ° C.) 50.00 parts and a polyol having a rosin skeleton in the molecule (Arakawa Chemical Industries, Ltd., KE-615-3, number average molecular weight 2000)
After mixing and stirring at 5 ° C. at 100 ° C. and degassing in vacuo for 45 minutes, 18.07 parts of 4,4′-diphenylmethane diisocyanate was added and reacted at 90 ° C. for 6 hours under a nitrogen stream. Thus, a reactive hot melt adhesive composition of Comparative Example having a melting point of 49 ° C. and a number average molecular weight of 7,600 was prepared.

Comparative Example 3 A commercially available ethylene-vinyl acetate copolymer-based hot melt adhesive for binding (Asahi Melt M3 manufactured by Asahi Synthetic Chemical Co., Ltd.)
110) was used.

Each of the above-obtained adhesives was heat-melted to 120 ° C. using a bookbinding machine.
Coating was performed to a thickness of 00 μm and bonded to a book in a molten state to perform bookbinding. In addition, about the adhesive of the comparative example 3, 18
The coating was performed at 0 ° C. to a thickness of 1000 μm. The adhesive strength, book spreadability, and cold / heat resistance of each bonded article were evaluated by the following measurement methods.

(Adhesive Strength) After bonding the above-mentioned adhesives, they were left for 2 minutes, 5 minutes, and 24 hours, and cut into 25 mm width test pieces, which were subjected to a tensile test using an Instron tester. The load when the adhesive layer was cohesively fractured or the substrate was fractured was measured and determined as the adhesive strength. Table 1 shows the evaluation results.

(Book Spreading Property)
After leaving for 1 week in an atmosphere of 5 ° C. and a humidity of 65% RH, the book having the adhesive layer and the middle book bonded together was opened by hand, and the spread was evaluated as follows. Judgment was made based on the following criteria. Table 2 shows the evaluation results. Evaluation points: ：: The phenomenon that the book is closed even after the book is opened and left to stand is not recognized. Δ: A phenomenon in which the page slightly rises when the book is opened and left for a long time is recognized. ×: A phenomenon in which the book naturally closes when the hand is released after opening the book is recognized.

(Cold resistance and heat resistance) The adhesive was left to stand at -30 ° C for 10 hours, and then subjected to a heat cycle test 60 times, in which one cycle was left at 70 ° C for 10 hours. In addition, the adhesive strength was determined by the above-mentioned adhesive strength measuring method. Table 2 shows the evaluation results. ：: No dissociation phenomenon (loose, floating) between the cover and the central book was observed. ×: The cover and the central book are dissociated, and a loose book state is recognized.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

According to the present invention, a polyfunctional isocyanate compound, a crystalline polyester polyol, a non-crystalline polyester polyol, and a polyol having a rosin skeleton are reacted to obtain an initial adhesive strength and book spreadability. And a reactive hot-melt adhesive composition having moisture-curing performance with excellent cold resistance and heat resistance.

Claims (9)

[Claims] 1. A polyfunctional isocyanate compound (component A)
, A crystalline polyester polyol (component B), a non-crystalline polyester polyol (component C), and a polyol having a rosin skeleton (component D). object. 2. The component A is a compound having two or more isocyanate groups at a terminal or a relatively low molecular weight isocyanate compound containing a terminal isocyanate group which is a reaction product of the compound and a low molecular weight polyol. The reactive hot melt adhesive composition according to claim 1. 3. The reactive hot melt adhesive composition according to claim 1, wherein the component B is a crystalline polyester polyol having a melting point of 40 to 90 ° C. and a number average molecular weight of 2,000 to 5,000. 4. The reactive hot melt adhesive composition according to claim 1, wherein the component C is a non-crystalline polyester polyol having a number average molecular weight of 2,000 to 5,000 which is liquid at normal temperature. 5. The reactive hot melt adhesive composition according to claim 1, wherein the component D is a polyol having a rosin skeleton and an OH group in the molecule each having an average of 1.8 to 2.2. 6. The blending ratio of the component B, the component C, and the component D is such that the component B is 10 to 60% by weight, the component C is 5 to 50% by weight, and the component D is 20 to 20% by weight based on all polyol components. 6
The reactive hot melt adhesive composition according to claim 1, which is 0% by weight. 7. The reactive hot melt adhesive composition according to claim 1, wherein a reaction equivalent ratio (NCO / OH) of the component A to all polyol components is 1.2 to 2.5. 8. The reactive hot melt adhesive composition according to claim 1, which has a melting point of 40 to 150 ° C. 9. The reactive hot melt adhesive composition according to claim 1, which is used for bookbinding.