JPH06316689A - Reactive hot-melt adhesive - Google Patents

Abstract

PURPOSE:To provide a polyurethane-based reactive hot-melt adhesive coatable in a mlolten state at a temperatures of as low as 95-130 deg.C, high in initial tackiness, and long in adhesiveness-keeping time. CONSTITUTION:This reactive hot-melt adhesive consisting mainly of a prepolymer containing 1.5-5.5wt.% of isocyanate group can be obtained by reaction of (A) an organic isocyanate with (B) a polyester polyol 40-65 deg.C in melting point produced by condensation between (1) a diol and (2) adipic acid, suberic acid, sebacic acid or a diester thereof and/or a lactone-based polyester polyol 40-65 deg.C in melting point produced by ring opening polymerization of lactone ring and (C) as chain extender, a <=10C diol having, at least, one side chain alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane-based reactive hot melt adhesive. More specifically, the temperature of 95-
The present invention relates to a urethane-based reactive hot-melt adhesive that can be melt-coated at a low temperature of 130 ° C., has a large initial adhesive force, and has a long adhesive time.

[0002]

2. Description of the Related Art Conventionally, adhesives are roughly classified into hot melt type and reactive type. Usually, the hot melt type is made by using a high melting point polymer such as EVA as a base resin and adding a tackifier to the base resin.
The adhesive workability is excellent because the adhesive force can be obtained in a short time by applying to an adherend in a heat-melted state of around ℃ and cooling and solidifying. On the other hand, since it is based on a thermoplastic resin, the adhesive strength is remarkably reduced at high temperatures and the heat resistance is poor.

On the other hand, the reaction (curing) type is excellent in heat resistance because it is cross-linked and cured by a chemical reaction, but since the curing system involves a reaction, the adhesive strength is remarkably low in the early stage of the reaction.
There is a drawback that a large adhesive force cannot be obtained from the initial stage like the hot melt type.

As the above-mentioned improvement, polyester-based and polyamide-based hot-melt adhesives having improved heat resistance of hot-melt type adhesives have been put on the market, but these require melt coating at a high temperature of about 200 ° C. It is difficult to adapt to non-heat-resistant adherends such as plastics.

[0005] Further, as the use of hot melt type adhesives expands, long-term adhesive strength retention is required in addition to heat resistance. These have also been used in fields such as automobile interiors and building materials. Therefore, there is also a demand for a so-called initial tacky hot melt adhesive having a bondable time (open time) that is as long as possible after application when an adherend having a large area is subjected to adhesion processing.

That is, it is desired to develop a hot melt adhesive which exhibits a strong adhesive force immediately after coating and exhibits excellent adhesive force for a long period of time under various conditions due to a crosslinking reaction or the like after laminating and bonding. In response to these requirements, so-called reactive hot melt adhesives are being developed in which a crosslinking reaction is caused by some method after adhesion to improve heat resistance. As a reactive hot melt adhesive, for example, an ion-crosslinking type hot melt adhesive by a carboxyl group and a polyvalent metal ion in a polymer, a molecular end, or an isocyanate group introduced into a side chain is blocked with a blocking agent such as caprolactam or phenol. Blocked isocyanate type hot melt adhesives, and moisture curing type hot melt adhesives in which an isocyanate group or an alkoxy group that crosslinks by reacting with moisture (moisture) are introduced into a polymer have been proposed (Adhesion Technology VoL. 19, No. 2
(1990)) was not obtained.

However, the above-mentioned reactive hot-melt adhesive can surely bond for a short time like the conventional hot-melt adhesive, and is superior in heat resistance to the conventional hot-melt adhesive. . In particular, various urethane reactive hot melt adhesives have been proposed as those having excellent overall characteristics including economic efficiency (Japanese Patent Laid-Open No. 59-197432,
JP-A-61-115977, JP-A-62-18137
5, JP-A-2-305881, JP-A-2-30588
2).

The urethane-based reactive hot-melt adhesive as described above contains an isocyanate group contained in the urethane prepolymer molecule as the main component and an active hydrogen compound of the base material and / or
Or, by reacting with moisture (moisture) contained in the atmosphere etc. and curing, it is superior in heat resistance as compared with conventional hot melt adhesives, but storage stability, initial adhesive strength expression,
There are points that need to be improved, such as open time and long-term durability, which are not yet fully satisfactory, and improvements are strongly desired.

The urethane-based reactive hot melt adhesive is
A urethane prepolymer having an isocyanate group-containing molecular weight of several thousand is used as the base resin of the main component, and depending on the case, a tackifier, a reactivity modifier, an antioxidant, a hydrolysis inhibitor, an antifoaming agent, an inorganic additive ( It is made by adding various additives such as a filler. Isocyanate groups contained in the prepolymer molecule are water on the surface of the adherend, bound water,
By reacting with active hydrogen groups such as OH groups, COOH groups, NH groups and moisture in the atmosphere, and by forming a bond with high cohesive energy such as a urea bond / urethane bond, the molecule is extended and cross-linked to obtain adhesive strength and It is said to develop heat resistance.

Further, there are the following two types of polyurethane-based reactive hot-melt adhesives which can be melt-coated at a low temperature, have a large initial adhesive force, and have a long adhesive time. On the other hand, an isocyanate group-containing prepolymer obtained by reacting a low-melting-point high-molecular-weight polyol having low crystallinity as a polyol with a polyisocyanate under an isocyanate group excess condition is used as a base polymer of a reactive hot melt adhesive.
Others include, for example, a high-melting point, high-molecular-weight polyol reacted with a diisocyanate under an isocyanate group excess condition to give an isocyanate group-containing prepolymer, to which a tackifier such as petroleum resin or coumarone resin is added to impart tackiness. . The former has an unnecessarily low melting point, so that the initial adhesive force rises very slowly and lacks the operability which is an advantage of the hot melt adhesive. The latter is capable of enhancing the initial tackiness without sacrificing the operability by adjusting the addition amount of the tackifier, but shows a plasticizing action because the tackifier is a low molecule, and Many of these tackifiers gradually bleeded and had poor rise in adhesive strength, final adhesive strength and long-term durability. The conventional hot melt adhesive has an open time of only seconds to minutes, and there is a problem in workability in bonding using a large-area non-heat-resistant plastic as an adherend.

[0011]

DISCLOSURE OF THE INVENTION The present inventors have developed a urethane-based adhesive type reactive hot melt adhesive excellent in long-term adhesion durability, and by using a polyurethane resin having a specific structure as a base polymer. It is intended to obtain a urethane-based reactive hot melt adhesive having the following characteristics. (1) It can be used for a plastic adherend having a large area and having no heat resistance. (2) It can be melted at a low temperature and applied by a roll coater or a spray. (3) The bondable time (the time during which the base materials can be brought into close contact with each other with a weak pressure and adhered without reheating during coating) is long. (4) Adhesive strength rises quickly after joining. (5) Since the internal strain of the adhesive layer is small, the adhesive force is large.

[0012]

That is, the present invention relates to (A) a polyester having a melting point of 40 ° C. or higher and 65 ° C. or lower obtained from a condensation reaction of a diol with adipic acid, suberic acid, sebacic acid and diesters thereof as a polyol. Polyol and / or lactone polyester polyol obtained by ring-opening polymerization of lactone ring and having a melting point of 40 ° C. or higher and 65 ° C. or lower (B) A diol having 10 or less carbon atoms and at least one side chain alkyl group as a chain extender (C ) Organic Isocyanate The above components (A), (B), and (C) are used as essential components, and an equivalent ratio of 0 <(B) / (A) = <0.80 and 1.2 <
(C) / {(A) + (B)} <2.5 and is composed mainly of an isocyanate group-containing prepolymer having an isocyanate group content of 1.5 to 5.5% by weight. Reactive hot melt adhesive. In the above reactive hot melt adhesive, a diol (B ₁ ) having 10 or less carbon atoms and at least one side chain alkyl group and a linear diol (B ₂ ) are used together as a chain extender of the component (B),
Equivalent ratio 0 <(B ₁ ) / (A) = <0.80, and 0 <
{(B ₁ ) + (B ₂ )} / (A) <1.0, 1.2 <
(C) <{(A) + (B)} <2.5, wherein the main component is an isocyanate group-containing prepolymer having an isocyanate group content of 1.5 to 5.5% by weight. It is a reactive hot melt adhesive.

This reactive hot melt adhesive is 95-1.
Melt coating is possible at a low temperature of 30 ° C., it rapidly solidifies when cooled to about 60 ° C. or less, and the initial adhesive force is given by the cohesive force due to the concentrated urethane bond due to the chain of the components (B) and (C). However, due to the influence of the side chain of the component (B) introduced as a chain extender, the entire base polymer of the hot melt adhesive does not crystallize, and the tackiness is exhibited for a certain period of time. Although depending on the subsequent time and the environmental temperature, the tackiness gradually decreases due to the aggregation of the soft segment by the component (A). At the same time, the isocyanate group reacts with moisture or active hydrogen on the surface of the adherend, and the prepolymer with a molecular weight of several thousand is urea-bonded.
The molecule is extended and cross-linked with the formation of a bond having a high cohesive energy such as a urethane bond to improve the adhesive strength and develop heat resistance.

The components constituting the reactive hot melt adhesive of the present invention will be described below. The polyester polyol (A) of the present invention has a molecular weight of 500 to 8000. Specifically, diester compounds such as adipic acid, suberic acid, sebacic acid and their dimethyl esters, and ethylene glycol, diethylene glycol, 1,3-
Propylene glycol, 1,2-propylene glycol, 1,4-butanediol (1,4-BD), 1,5
-Pentanediol, 1,6-hexanediol (1,
6-HD), neopentyl glycol (NPG), 3-
Methyl-1,5-pentanediol (3-MPD),
It is obtained by dehydration or dealcoholization condensation reaction with at least one selected from a diol group such as 1,8-octanediol. As the diol, one having a large number of carbon atoms is preferable in consideration of hydrolysis resistance. Further, straight-chain diols are suitable because the initial adhesiveness rises at an appropriate speed, and 1,4-BD and 1,6-HD are particularly preferred.

The lactone-based polyester polyol obtained by ring-opening polymerization of the lactone ring has a molecular weight of 50.
It is 0 to 7000. Specifically, those obtained from caprolactone or δ-valerolactone using a diol such as ethylene glycol, diethylene glycol or NPG as an initiator, or a diol containing a lactone ester as a main component obtained by an exchange reaction with another polyester diol, etc. Is.

The melting point is measured by a differential thermal analyzer (heating temperature 10 ° C. /
The value obtained from the endothermic peak at (min.) Is used, but a value that is not so different can be obtained when obtained with a transmission melting point measuring device, for example. When the melting point is 40 ° C. or lower, the initial adhesive force of the hot melt adhesive is slow to develop, and the operability, which is an advantage of the hot melt adhesive, is lacking. On the other hand, when the temperature is 65 ° C. or higher, the initial rise of the adhesive strength is good, but there is a shrinkage associated therewith, which may cause peeling or insufficient adhesion, which is not preferable.

The chain extender (B) of the present invention is a diol, has 10 or less carbon atoms, has at least one side chain alkyl group, and has a molecular weight of 62 to 200. Specifically, 1,2-propylene glycol, 1,3-butanediol (1,3-B
D), NPG, 3-MPD, 2,2,4-trimethyl-
1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-diethyl-1,3-propanediol (DMP), 2-n-butyl-2-ethyl-propanediol (DMH), etc. Is mentioned. As the base polymer of the urethane-based reactive hot-melt adhesive, a linear polyol is generally used in order to enhance the crystallinity and accelerate the initial rising. The present inventors have found that a short-chain diol (hereinafter abbreviated as “branched diol”) having a side chain introduced therein is used as a chain extender in a urethane-based reactive hot-melt adhesive to show a unique action.

These branched diols are essential components for imparting appropriate initial tackiness to the adhesive to the reactive hot melt and for alleviating internal strain generated in the adhesive layer due to rapid rise of initial adhesive force. is there. The equivalent ratio of the branched diol (B) to the polyester polyol (A) is 0.8.
The following are preferred. When this is 0 (in the case of only the polyester polyol shown in (A)), the initial rising is early, but the tackiness is insufficient, and the internal strain cannot be relaxed, and the shear stress or impact immediately after the bonding is applied. In that case, peeling may occur, which is not preferable.

When the branched diol is introduced in an amount of more than 0.8, the amount of side chains introduced into the reactive hot melt adhesive is large, the initial tackiness is sufficient, and the internal strain is relaxed. Although it has excellent impact resistance, it is not preferable because the workability as a hot melt adhesive is poor because the crystallization speed is extremely low and the adhesive force rises slowly. A straight chain diol without branching can be used as an extender in combination with the branched diol of (B). In this case, the combined ratio of (B) / (A) is preferably 1.0 or less. 1.0
If it exceeds, the heating and melting temperature becomes high, and the melt coating becomes difficult at a low temperature of 95 ° C to 130 ° C, which is a feature of the present invention.

Examples of the organic isocyanate (C) of the present invention include tolylene diisocyanate (TDI), xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyl ether diisocyanate and 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 diisocyanate such as 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, tetramethylene diisocyanate,
Aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) and lysine diisocyanate, diisocyanates such as isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate (H ₁₂ MDI), and the like. .

Further, a polymeric polyisocyanate, which is a polyisocyanate having an isocyanate group obtained by the reaction of the above-mentioned polymer of diisocyanate or difunctional or higher functional polyol, etc. with the above-mentioned diisocyanate compound and the polymer, polyol adduct of isocyanate, and uretdione. , Isocyanurate, and carbodiimide modified products are also included. Particularly preferred are aromatic diisocyanates such as MDI, PPDI and TDI and H ₁₂ MDI from the standpoint of the initial adhesive strength and the durability of the adhesive layer.

Further, it is essential that this reactive hot melt adhesive contains an isocyanate group which reacts with active hydrogen and moisture in the molecule, and the equivalent ratio of hydroxyl group and isocyanate group (NCO / OH), that is, ( C) / {(A) +
(B)} is 1.2 to 2.5, and the isocyanate group content is preferably 1.5 to 5.5% by weight.
When (C) / {(A) + (B)} is 1.2 or less, the heat resistance of the adhesive layer is inferior, and the molecular weight is too large and the viscosity in the molten state is too high, resulting in poor operability. When it exceeds 2.5, unreacted diisocyanate remains, so that the diisocyanate has an odor at high temperature and the activity of this diisocyanate monomer is high, which is not preferable because the viscosity stability in a high temperature molten state is insufficient. On the other hand, if the isocyanate group content is 1.5% or less, the molecular weight becomes large and the viscosity in the molten state is too high, resulting in poor operability. If it is 5.5% or more, the molecular weight is too small, which hinders the operation of the roll coater.
Also, the initial strength is small, the improvement of the adhesive strength due to the reaction with active hydrogen and moisture is slow, and the peeling of the adhesive layer due to impact is not preferable.

In producing the isocyanate group-containing polyurethane prepolymer used in the reactive hot melt adhesive according to the present invention, a known method, for example, bulk polymerization (bulk polymerization) method of reacting in a molten state can be used. . For example, in an atmosphere of an inert gas such as nitrogen, a reactor having a powerful stirring device and a heating device, a kneader ruder,
Examples thereof include a method of heating and melting in a kneading machine such as a Hensiel mixer and a Nauter mixer, and manufacturing in an extruder and the like.

In producing the polyurethane prepolymer according to the present invention, a catalyst and a stabilizer can be used if necessary. Examples of the catalyst include nitrogen-containing compounds such as triethylamine and triethylenediamine, and organic metal compounds such as dibutyltin dilaurate (DBTDL), tin octylate and zinc stearate. As the stabilizer, for example, an ultraviolet absorber such as a substituted benzotriazole, an antioxidant such as a phenol derivative, a hydrolysis inhibitor, and a so-called retarder for controlling the reaction of an isocyanate group may be added.

Further, the reactive hot-melt adhesive of the present invention comprises an isocyanate group-containing polyurethane polymer as a main component, and if necessary, an isocyanate having an affinity with it, a non-reactive filler, a tackifier and a heat agent. You may add a plastic resin in the range of 10% or less, respectively. These may be added at the time of producing the prepolymer or may be added and mixed as a prepolymer. Further, it is preferable that the tackifier and the thermoplastic resin are mixed with the branched diol (B) and dissolved by heating so as to be in a uniform state and then reacted with the organic diisocyanate. As the filler, one or two selected from magnesium oxide, silica powder, calcium carbonate, carbon black, titanium oxide, metal powder, etc.
Included are dry fillers of one or more species. Typical examples of tackifiers are (hydrogenated) rosin ester derivatives, petroleum resins, terpene resins, coumarone-indene resins, xylene resins, ketone resins, etc., and thermoplastic resins include thermoplastic polyurethane resins, polyester resins, These are ethylene-methyl acrylate resins and the like, and these can be used alone or as a mixture of two or more kinds.

In the present invention, a hot-melt adhesive of 95 ° C. to 130 ° C. can be melt-coated at a low temperature, and since it has an initial tackiness, it has a bonding time of several minutes to several tens of minutes. Adhesion of non-heat resistant plastics such as ABS and polypropylene, and adhesion of the above plastics etc. to aluminum, steel, paper, wood, etc.
It is particularly suitable for bonding these large-sized members.

The present invention will be described below with reference to specific examples. The components, ratios, operation sequences and the like shown below can be changed without departing from the spirit of the present invention. "Parts" and "%" in the examples are "parts by weight" unless otherwise specified.
And "% by weight".

Example 1 A reaction vessel equipped with a thermometer, a cooling device, a vacuum dewatering device, and a stirrer was charged with a polyester polyol (PBA-2000, hydroxyl value 56.1, consisting of 1,4-BD and adipic acid).
Molecular weight 2000, melting point 51.1 ° C.) 2000 parts, (1.
0 mol) 26.0 parts (0.25 mol) of NPG was added and 1
After dehydration treatment at 10 ° C. under vacuum, the mixture was cooled, and 485 parts (1.94 mol) of MDI was added at 40 ° C. or lower. Although the reaction causes heat generation and the viscosity rises rapidly, the temperature is cooled and the internal temperature is maintained at about 80 ° C. The temperature was maintained and the reaction was carried out for 3 hours.
The structure factor of the obtained prepolymer is (B) / (A) =
0.25, (C) / {(A) + (B)} = 1.55, properties are NCO content = 2.3%, viscosity = 23,000 mP
The melting point was 42 ° C. The result is tack-free time = 20 minutes, initial adhesive strength = 15 Kg / 25c
m ² , softening point (after 1 day) 130 ° C., softening point (after 7 days) 1
The temperature was 85 ° C. and the initial tackiness, adhesive strength and curability were satisfactory.

Example 2 A kneader equipped with a thermometer, a cooling device and a decompression vacuum device
Polyester polyol derived from 6-HD and adipic acid (hereinafter abbreviated as PHA-2500. Hydroxyl value 44.9, molecular weight 2520, melting point 55.1 ° C) 2520 parts (1.0 mol), NPG 41.6 parts (0. 40 mol) and add 1
After dehydration treatment under vacuum at 10 ° C., the mixture was cooled and 741 parts (2.96 mol) of MDI was added at 40 ° C. or lower. Although the reaction causes heat generation and the viscosity rises rapidly, the temperature is cooled and the internal temperature is maintained at about 80 ° C. The temperature was maintained and the reaction was carried out for 3 hours.
The structure factor of the obtained prepolymer is (B) / (A) =
0.40, (C) / {(A) + (B)} = 2.11, properties are NCO content = 4.0%, viscosity = 9,500 mPas
S / 100 ° C, melting point = 35 ° C. The result is tack-free time = 15 minutes, initial adhesive strength = 18 kg / 25 cm
² , softening point (after 1 day) 115 ° C, softening point (after 7 days) 19
The temperature was 0 ° C, and the initial tackiness, adhesive strength, and curability were satisfactory.

Examples 3 to 6 and Comparative Examples 1 and 2 Prepolymers were produced and evaluated by the same apparatus and method as in Example 1. The results are shown in Table 1.

[0031]

[Table 1]

Examples 7 and 8 and Comparative Examples 3 to 5 Prepolymers were produced and evaluated by the same apparatus and method as in Example 1. The results are shown in Table 2.

[0033]

[Table 2]

Examples 9, 10, 11 and Comparative Examples 6, 7 Prepolymers were produced and evaluated by the same apparatus and method as in Example 1. The results are shown in Tables 3 and 4.

[0035]

[Table 3]

[0036]

[Table 4]

Notes in Tables 1 to 3 Hydroxyl value 1) PBA-1000: poly (butylene) adipate diol 1000 112.2 2) PBA-2000: poly (butylene) adipate diol 2000 56.1 3) PHA-1500: poly (hexamethylene) Adipate) diol 1500 74.8 4) PHA-5000: Poly (hexamethylene adipate) diol 5000 22.4 5) PCL-2000: Poly (caprolactone) polyol 2000 56.1 6) PCL-5000: Poly (caprolactone) polyol 5000 22.4 7) PDS- 2000: poly (decamethylene) sebacate 2000 56.1 8) PHP-1000: poly (hexane) phthalate diol 1000 112.2 9) PHP-2000: poly (hexane) phthalate diol 2000 56.1 10) PHSbA-2000: poly (hexane) suberate diol 2000 56.1

The properties and results were measured by the following methods. Viscosity (mPa · s): Viscosity is the value at a temperature of 100 ° C. mPa · s / 100 ° C. Tack free time: Sampling from a roll coater set at 110 ° C., and room temperature (25 ° C.) with a bar coater heated to 100 ° C. ℃) glass plate coated amount of 75g / m
Apply with ² . Immediately start measuring the finger touch tack, and set the tack free time (minutes) as the time when the tack disappears. The tack-free time is a relative evaluation value of the bondable time. Initial adhesion force: A roll coater set at 110 ° C was used to apply 50g / m ² to a steel plate having a width of 300mm and a length of 1000mm with a test coater manufactured by Matsushita Industrial Co., Ltd., and after 5 minutes, a hard vinyl chloride (PVC) was stuck to the sample. To do. With respect to the initial adhesive force, a sample having a width of 25 mm is cut out after 3 hours and the tensile shear strength (kg / cm ² ) is measured with a tensilon.
* Varies depending on location and conditions. Adhesion after 7 days: 25 the above laminated sample
Tensile shear strength (kg /
cm ² ) is measured. SP (softening point): Created by the same method as used for tack-free measurement. After leaving the film sample for a predetermined number of days, it is heated at a temperature rising rate of 10 ° C./min by applying a load of 5 g / 100 μm, and the temperature at which the film abruptly extends is taken as the softening point (° C.).

[0039]

The urethane reactive hot melt adhesive of the present invention is excellent in long-term adhesion durability and has the following characteristics by using a polyurethane resin having a specific structure as a base polymer. (1) It can be used for a plastic adherend having a large area and having no heat resistance. (2) It can be melted at a low temperature and applied by a roll coater or a spray. (3) The bondable time (the time during which the base materials can be brought into close contact with each other with a weak pressure and adhered without reheating during coating) is long. (4) Adhesive strength rises quickly after joining. (5) Since the internal strain of the adhesive layer is small, the adhesive force is large.

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[Procedure amendment]

[Submission date] November 22, 1991

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[0012]

Means for Solving the Problems That is, the present invention provides (A) a polyol having a melting point of 40 ° C. or higher and 65 ° C. or lower, which is obtained by a condensation reaction of a diol with adipic acid, suberic acid, sebacic acid, and their diesters. And / or a lactone polyester polyol having a melting point of 40 ° C. or higher and 65 ° C. or lower obtained by ring-opening polymerization of a lactone ring (B) having 10 or less carbon atoms and at least one side chain alkyl group as a chain extender Diol (C) Organic Isocyanate The above (A), (B), and (C) are essential components, and the equivalent ratio is 0 <(B) / (A) ≦ 0.80 and 1.2 <(C) /
{(A) + (B)} <2.5 is a reaction type characterized by comprising an isocyanate group-containing prepolymer having an isocyanate group content of 1.5 to 5.5% by weight as a main component. It is a hot melt adhesive.

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[0036]

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[Procedure amendment]

[Submission date] May 19, 1994

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[0036]

[Table 5]

Claims (2)

[Claims] 1. A polyester polyol having a melting point of 40 ° C. or higher and 65 ° C. or lower and / or a lactone ring obtained by a condensation reaction of a diol with adipic acid, suberic acid, sebacic acid and their diesters as the polyol (A). Lactone-based polyester polyol having a melting point of 40 ° C. or higher and 65 ° C. or lower (B) a chain extender having 10 or less carbon atoms and at least one side chain alkyl group (C) organic isocyanate obtained by ring polymerization (A), (B) and (C) are essential components, and the equivalent ratio is 0 <(B) / (A) = <0.80 and 1.2 <(C).
/{(A)+(B)}<2.5, wherein the main component is an isocyanate group-containing prepolymer having an isocyanate group content of 1.5 to 5.5% by weight. Type hot melt adhesive. 2. A chain extender of the component (B) according to claim 1, wherein a diol (B ₁ ) having 10 or less carbon atoms and at least one side chain alkyl group and a linear diol (B ₂ ) are used in combination, and an equivalent weight is used. The ratio is 0 <(B ₁ ) / (A) = <0.80, and 0 <
{(B ₁ ) + (B ₂ )} / (A) <1.0, 1.2 <
(C) / {(A) + (B)} <2.5 and is composed mainly of an isocyanate group-containing prepolymer having an isocyanate group content of 1.5 to 5.5% by weight. Reactive hot melt adhesive.