JP2019065220A - Reactive hot-melt adhesive composition - Google Patents

Abstract

To provide a reactive hot-melt adhesive composition which is excellent in thermal stability and has high adhesive strength even when applied to a member having low moisture permeability.SOLUTION: The reactive hot-melt adhesive composition contains: a urethane prepolymer which has a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and has an isocyanate group at a terminal of the polymer chain; and a morpholine-based curing catalyst. The polyol contains a polyether polyol having a group represented by formula (1).SELECTED DRAWING: None

Description

  The present invention relates to reactive hot melt adhesive compositions.

  Hot melt adhesives are widely used in the industry because they are non-solvent adhesives and therefore have less impact on the environment or human body, and because they can be adhered for a short time and are suitable for improving productivity, . Hot melt adhesives can be roughly classified into two, those having a thermoplastic resin as a main component and those having a reactive resin as a main component. As a hot melt adhesive containing a thermoplastic resin as a main component, EVA (ethylene vinyl acetate copolymer) is mainly used.

  On the other hand, as for the hot melt adhesive which has a reactive resin as a main component, the urethane prepolymer of the isocyanate group terminal is mainly used, and it is called a reactive hot melt adhesive. After bonding, the reactive hot melt adhesive develops a certain degree of adhesive strength in a short time by cooling and solidifying the adhesive itself. Thereafter, the terminal isocyanate group of the urethane prepolymer reacts with water in the air or on the surface of the adherend to produce high molecular weight and crosslink, thereby exhibiting good adhesive strength.

  Bonding materials such as double-sided pressure-sensitive adhesive tapes, etc. for bonding metal members that are widely used in electronic parts, electric appliances, building members, household goods, industrial materials, etc., thermosetting materials or light curing Mold adhesives, reactive hot melt adhesives and the like are used. With the widespread use of information display terminals such as mobile phones, personal computers and televisions, these materials or adhesives are required to strongly bond metal members to non-metal members such as plastic members and glass members. There is.

  In a recent display terminal, the bonding part area of parts becomes narrow, and parts of complicated shape are increasing. Reactive hot melt adhesives are particularly noteworthy because they can be applied in a wide variety of shapes and react with moisture in the air or on the surface of the adherend to obtain good adhesive strength. There is. By the way, since the adhesive strength is improved by reacting the reactive hot melt adhesive with the moisture in the air or the surface of the adherend, the adhesive strength is developed when applied to a member with low moisture permeability such as metal and glass. There is a problem that it is difficult to do.

  As a reactive hot melt adhesive composition used for such an application, the composition of patent documents 1-3 is indicated, for example. However, even in the case of the conventional reactive hot melt adhesive composition, the adhesive strength is not sufficient and there is still room for improvement.

JP 2003-171640 A JP-A-8-027454 Japanese Patent Laid-Open No. 7-258620

  The present invention has been made in view of such circumstances, and provides a reactive hot melt adhesive composition having high adhesive strength even when applied to a member having excellent thermal stability and low moisture permeability. The main purpose is to

  As a result of intensive studies to achieve the above object, the present inventors have found that a reactive hot melt adhesive composition can be obtained by using a polyether polyol having a high ratio of primary hydroxyl groups as a polyol constituting a urethane prepolymer. It has been found that the thermal stability and adhesive strength of the above can be improved, and the present invention has been completed.

  The present invention provides a moisture-curable reactive hot melt adhesive composition shown in the following [1] to [4].

［２］ポリエーテルポリオールの含有量が、ポリオール１００質量部に対して、５〜５５質量部である、［１］に記載の反応性ホットメルト接着剤組成物。
［３］ポリエーテルポリオールが、ポリエチレングリコールである、［１］又は［２］に記載の反応性ホットメルト接着剤組成物。
［４］モルホリン系硬化触媒の含有量が、ポリオール１００質量部に対して、０．１〜０．９質量部である、［１］〜［３］のいずれか一項に記載の反応性ホットメルト接着剤組成物。 [1] A polyol comprising a urethane prepolymer having a polymer-derived structural unit derived from a polyol and a structural unit derived from a polyisocyanate and having an isocyanate group at the end of the polymer chain, and a morpholine-based curing catalyst; Reactive hot melt adhesive composition containing the polyether polyol which has group represented by following formula (1).

[2] The reactive hot melt adhesive composition according to [1], wherein the content of the polyether polyol is 5 to 55 parts by mass with respect to 100 parts by mass of the polyol.
[3] The reactive hot melt adhesive composition according to [1] or [2], wherein the polyether polyol is polyethylene glycol.
[4] The reactive hot according to any one of [1] to [3], wherein the content of the morpholine-based curing catalyst is 0.1 to 0.9 parts by mass with respect to 100 parts by mass of the polyol. Melt adhesive composition.

  According to the present invention, it is possible to provide a reactive hot melt adhesive composition having high adhesive strength even when applied to a member having excellent thermal stability and low moisture permeability.

  Hereinafter, modes for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  As used herein, "polyol" means a compound having two or more hydroxyl groups in the molecule.

  As used herein, "polyisocyanate" means a compound having two or more isocyanate groups in the molecule.

<Reactive Hot Melt Adhesive Composition>
A reactive hot melt adhesive composition according to one embodiment includes a urethane prepolymer having a polymer chain including a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and having an isocyanate group at the end of the polymer chain And morpholine-based curing catalyst. The polyol includes a polyether polyol having a group represented by the formula (1) (that is, a primary hydroxyl group) (hereinafter, sometimes referred to as “specific polyether polyol”).

[Urethane Prepolymer]
Urethane prepolymers having a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and having an isocyanate group at the end of the polymer chain usually contain the polyisocyanate (B) in the polyol (A). It can be obtained by reaction. That is, the urethane prepolymer may be a reactant of polyol (A) and polyisocyanate (B).

(Polyol (A))
The polyol (A) contains a polyether polyol (specific polyether polyol (A ′)) having a group represented by the formula (1).

  In the specific polyether polyol (A ′), all of the hydroxyl groups in the molecule may have a group represented by formula (1), and a part of the hydroxyl groups is a group represented by formula (1) You may have. Examples of the specific polyether polyol (A ') include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and the like. As the specific polyether polyol (A ′), one type may be used alone, or two or more types may be used in combination. Among these, the specific polyether polyol (A ′) is preferably polyethylene glycol or polypropylene glycol, and more preferably polyethylene glycol. Such a polyol can be obtained, for example, by polymerizing an oxirane such as ethylene oxide, propylene oxide or tetrahydrofuran with water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin or the like as an initiator.

  In the case of using oxirane in which the alpha carbon of ether bond such as ethylene oxide and tetrahydrofuran is a primary carbon atom, the obtained polyethylene glycol, polytetramethylene ether glycol and the like have all hydroxyl groups in the molecule represented by the formula (1) It can be the basis.

  When propylene oxide in which the alpha carbon of an ether bond is a secondary carbon atom is used as the oxysilane, β-cleavage of propylene oxide usually proceeds to tend to obtain a polypropylene glycol having a secondary hydroxyl group. By predominantly α-cleavage, polypropylene glycol having a group (primary hydroxyl group) represented by the formula (1) can be obtained at a high ratio. Such polypropylene glycols are commercially available as primary hydroxyl group-containing polypropylene glycols. As such commercial products, for example, the ratio of polyethylene glycol having a group (primary hydroxyl group) represented by “FF-2100” (manufactured by Sanyo Chemical Industries, Ltd., formula (1): about 70 mol%, secondary The proportion of polyethylene glycol having a hydroxyl group: about 30 mol%) and the like can be mentioned.

  The number average molecular weight (Mn) of the specific polyether polyol (A ') is preferably 500 to 20,000, more preferably 700 to 15,000, and more preferably 1,000 to 10,000, from the viewpoint of obtaining an adequate bondable time after application and initial adhesion. Is more preferred.

In the present specification, the number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene. The measurement of GPC can be performed under the following conditions.
Columns: “Gelpack GLA130-S”, “Gelpack GLA150-S” and “Gelpack GLA160-S” (manufactured by Hitachi Chemical Co., Ltd., packed column for HPLC)
Eluent: tetrahydrofuran Flow rate: 1.0 mL / min Column temperature: 40 ° C
Detector: RI

  The content of the specific polyether polyol (A ') may be 5 to 55 parts by mass with respect to 100 parts by mass of the polyol. The content of the specific polyether polyol (A ′) is more preferably 8 parts by mass or more, further preferably 10 parts by mass or more with respect to 100 parts by mass of the polyol. When the content of the specific polyether polyol (A ′) is 5 parts by mass or more, when applied to a member having low moisture permeability, it tends to exhibit more excellent adhesive strength. The content of the specific polyether polyol (A ′) is more preferably 52 parts by mass or less, and still more preferably 50 parts by mass or less with respect to 100 parts by mass of the polyol. If the content of the specific polyether polyol (A ′) is 55 parts by mass or less, the thermal stability tends to be more excellent.

  The polyol (A) may contain a polyol other than the specific polyether polyol (A '). Examples of such polyols include polyester polyols, polyether polyols other than the specific polyether polyol (A '), polyether ester polyols, polyurethane polyols, polycarbonate polyols, polyolefin polyols and the like. One such polyol may be used alone, or two or more may be used in combination. From the viewpoint of adhesion, the polyol (A) preferably contains a polyester polyol. Moreover, it is preferable that a polyol (A) is diol (dihydric alcohol) from a viewpoint of reaction control.

  As polyester polyol, the polyester polyol etc. which are obtained by the polycondensation reaction of the polyhydric alcohol which has a 2 or 3 hydroxyl group, and the polyhydric carboxylic acid which has a 2-6 carboxyl group are mentioned, for example.

  Examples of polyhydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, isomers of butanediol, isomers of pentanediol, isomers of hexanediol, 2, 2- Dimethyl-1,3-propanediol, 2-methylpropanediol, 2,4,4-trimethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,4-cyclohexane Aliphatic or alicyclic diols such as diol and 1,4-cyclohexanedimethanol; and aromatic diols such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resorcinol, hydroquinone and the like. A polyhydric alcohol may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, polyhydric alcohols having 2 to 15 carbon atoms are preferred.

  Examples of polyvalent carboxylic acids include aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid and 1,2,4-benzenetricarboxylic acid; maleic acid, fumaric acid, aconitic acid, 1, 2, 3 -Propane tricarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid, 1,4-cyclohexanediene-1,2-dicarboxylic acid, etc. Aliphatic or alicyclic polyhydric carboxylic acids can be mentioned. A polyhydric carboxylic acid may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, polyhydric carboxylic acids having 2 to 15 carbon atoms are preferred. In addition, it may replace with polyhydric carboxylic acid and may use the anhydride or polyhydric carboxylic acid alkyl ester.

  The polyester polyol may be a crystalline polyester polyol or an amorphous polyester polyol. Judgment of "crystalline" and "amorphous" is judged in the state at 25 ° C. As used herein, "crystalline polyester polyol" means a polyester polyol that is crystalline at 25 ° C. "Amorphous polyester polyol" means a polyester polyol that is amorphous at 25 ° C. The polyester polyol preferably contains both a crystalline polyester polyol and an amorphous polyester polyol from the viewpoint of further improving the coatability and initial adhesion of the adhesive composition.

  The number average molecular weight (Mn) of the crystalline polyester polyol is preferably 500 to 10000, more preferably 800 to 9000, and still more preferably 1000 to 8000, from the viewpoint of waterproofness and final adhesive strength.

  The content of the polyester polyol is preferably 45 to 95 parts by mass, more preferably 48 to 92 parts by mass, with respect to 100 parts by mass of the polyol, from the viewpoint of further improving adhesion. More preferably, it is part by weight.

  As polyether polyols other than a specific polyether polyol (A '), the polypropylene glycol etc. which have a secondary hydroxyl group are mentioned, for example.

  Examples of polyether ester polyols include polyether ester polyols obtained by reacting a polyvalent carboxylic acid with the above polyether polyol (including a specific polyether polyol (A ′)). Here, the polyvalent carboxylic acid can be exemplified by the same as the polyvalent carboxylic acid of the above polyester polyol.

  As a polyurethane polyol, for example, the above-mentioned polyester polyol, the above-mentioned polyether polyol (including the specific polyether polyol (A ')), a polyol such as the above-mentioned polyether ester polyol and polyisocyanate, isocyanate group (NCO) equivalent / hydroxyl group The polyurethane polyol obtained by making it react so that (OH) equivalent (NCO / OH) may become less than 1, preferably 0.9 or less is mentioned.

  Examples of polycarbonate polyols include polycarbonate polyols obtained by reacting a polyhydric alcohol having 2 or 3 hydroxyl groups with a carbonate compound or phosgene; and cyclic carbonate compounds with polyols such as polyether polyols, polyester polyols, polycarbonate polyols, etc. The polycarbonate polyol obtained by ring-opening polymerization is mentioned.

  Examples of polyolefin polyols include polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, and hydrogenated polyisoprene polyols.

(Polyisocyanate (B))
The polyisocyanate (B) can be used without particular limitation as long as it is a polyisocyanate having two or more isocyanate groups. As a polyisocyanate (B), aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate etc. are mentioned, for example. The polyisocyanate may be used alone or in combination of two or more.

  Examples of aromatic polyisocyanates include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 2,4'- or 4,4'-diphenylmethane diisocyanate, 4, 4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4 ′, 4 ′ ′-triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate, m- or p-xylylene diisocyanate, α, α, α ′, α′-tetramethyl xylylene diisocyanate Etc.

  Examples of aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,6,11-undecanetriisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, Examples include 6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate and the like.

  As an alicyclic polyisocyanate, for example, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexene-1,2-diisocyanate Carboxylate, 2,5- or 2,6-norbornane diisocyanate, etc. may be mentioned.

  From the viewpoint of reactivity, it is preferable to use diisocyanate as the polyisocyanate (B). Examples of diisocyanates include 2,4'- or 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 3,3'-dimethyl-4,4'-diisocyanate. Natodiphenylmethane, 2,4- or 2,6-tolylene diisocyanate, hexamethylene diisocyanate, m- or p-xylylene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, etc. may be used.

  The urethane prepolymer has an isocyanate group at the end of a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate. When synthesizing such a urethane prepolymer, it is preferable to adjust the mixing ratio of polyisocyanate and polyol so that the isocyanate group (NCO) equivalent of polyisocyanate / hydroxyl group (OH) equivalent of polyol is adjusted to 1.3 or more. It is more preferable to adjust to 1.5 to 3.5. When the isocyanate group (NCO) equivalent / hydroxyl group (OH) equivalent is 1.3 or more, the increase in viscosity of the resulting urethane prepolymer can be suppressed, and the workability tends to be easily improved. When the isocyanate group (NCO) equivalent / hydroxyl group (OH) equivalent is 3.5 or less, foaming in the case of the moisture curing reaction of the adhesive composition is less likely to occur, and it tends to be easy to suppress the decrease in adhesion. .

[Morpholine curing catalyst]
The reactive hot melt adhesive composition according to the present embodiment contains a morpholine-based curing catalyst. By using a urethane prepolymer containing a specific polyether polyol (A ') and a morpholine curing catalyst in combination, the curing reaction of the adhesive composition can be sufficiently achieved when applied to a member with low moisture permeability such as metal and glass. Since it can be promoted, high adhesive strength can be obtained. In the present specification, "morpholine-based" means a group of compounds having a morpholine ring.

  Examples of morpholine-based curing catalysts include N-ethyl morpholine, bis (morpholinoethyl) ether, bis (2,6-dimethylmorpholinoethyl) ether, bis (3,5-dimethylmorpholinoethyl) ether, bis (3,6 -Dimethylmorpholinoethyl) ether, 4- (3,5-dimethylmorpholino) -4 '-(3,6-dimethylmorpholino) diethylether and the like.

  The content of the morpholine-based curing catalyst is preferably 0.1 to 0.9 parts by mass, and more preferably 0.2 to 0.7 parts by mass with respect to 100 parts by mass of the polyol. When the content of the hard morpholine-based curing catalyst is 0.1 parts by mass or more with respect to 100 parts by mass of the polyol, curing tends to be more sufficient and the adhesive strength is further improved. When the content of the morpholine-based curing catalyst is 0.9 parts by mass or less with respect to 100 parts by mass of the polyol, the increase in viscosity can be further suppressed, and the heat stability tends to be more excellent.

[Other ingredients]
From the viewpoint of improving adhesiveness and impact resistance, a resin component which is not reactive with the urethane prepolymer may be added as another component to the reactive hot melt adhesive composition according to the present embodiment. Examples of resin components that do not react with the urethane prepolymer include polybutene, polybutadiene, an ester plasticizer, an acrylic plasticizer, a rosin resin (a rosin resin, a rosin ester resin, a hydrogenated rosin ester resin), and a terpene resin ( Terpene resin, hydrogenated terpene resin) etc. are mentioned. The content in the case of containing a urethane prepolymer and a non-reacting resin component is 0.1 to 50 parts based on 100 parts by mass of the total amount of the reactive hot melt adhesive composition from the viewpoint of moisture curing property, adhesiveness and the like. It is preferable that it is a mass part, and it is more preferable that it is 0.2-30 mass parts.

  A pigment, a dye, an antioxidant, an ultraviolet absorber, a surfactant, a flame retardant, a filler, and the like may be added to the reactive hot melt adhesive composition according to the present embodiment, as necessary.

<Method of producing reactive hot melt adhesive composition>
The reactive hot melt adhesive composition according to the present embodiment comprises a step of reacting a polyol and a polyisocyanate to obtain a urethane prepolymer, and a step of reacting a urethane prepolymer and a morpholine-based curing catalyst. Manufactured by the method.

  The urethane prepolymer may be obtained by reacting a product of a polyol and a polyisocyanate with a morpholine-based curing catalyst as it is, and a product of a reaction of a polyol and a polyisocyanate is previously isolated and then the morpholine-based curing catalyst is used. You may make it react.

  The reactive hot melt adhesive can be formed by applying the reactive hot melt adhesive composition according to the present embodiment. The coating method is not particularly limited, and examples thereof include methods using a coating apparatus such as a die coater, a roll coater, or a spray. A dispenser is suitable for application to narrow parts such as small parts.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these.

[Preparation of Reactive Hot Melt Adhesive Composition]
<Examples 1 to 9, Comparative Examples 1 and 2>
The polyol (A) and the polyisocyanate (B) containing the specific polyether polyol (A ') dehydrated beforehand were added to the reaction vessel in the amounts shown in Table 1. In addition, the below-mentioned (B1) was used for polyisocyanate (B). Moreover, the compounding quantity of (B1) is a table of the hydroxyl group (OH) equivalent (NCO / OH) of the polyol (A) containing the isocyanate group (NCO) equivalent / specific polyetherpolyol (A ') of polyisocyanate (B). It adjusted so that it might become a numerical value shown by 1. This mixture is reacted at 110 ° C. for 30 minutes under a nitrogen flow to obtain a urethane prepolymer having a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate and having an isocyanate group at the end of the polymer chain. A polymer was obtained. Then, a morpholine-based curing catalyst (C) is added to the urethane prepolymer and further reacted under vacuum at 110 ° C. for 45 minutes to obtain reactive hot melt adhesive compositions of Examples 1 to 9 and Comparative Examples 1 and 2. Obtained.

<Polyol (A)>
(Polyester polyol)
A1: crystalline polyester polyol (manufactured by Hitachi Chemical Co., Ltd., "A43", crystalline polyester polyol obtained mainly with adipic acid and 1,6-hexanediol, number of hydroxyl groups: 2, number average molecular weight: 5000)
A2: Crystalline polyester polyol (manufactured by Hitachi Chemical Co., Ltd., "A62", crystalline polyester polyol obtained mainly with adipic acid and 1,6-hexanediol, number of hydroxyl groups: 2, number average molecular weight: 2000)
A3: Amorphous polyester polyol (manufactured by Hitachi Chemical Co., Ltd., "TA 29-124", amorphous polyester polyol obtained mainly with isophthalic acid and neopentyl glycol, number of hydroxyl groups: 2, number average molecular weight: 2000)

(Polyether polyol)
A'1: Polyethylene glycol (manufactured by Shin Nippon Rika Co., Ltd., "PEG-4000S", number of hydroxyl groups: 2, number average molecular weight: 3400, polyethylene glycol having a group (primary hydroxyl group) represented by Formula (1) Ratio: 100 mol%)
A ′ 2: 1 grade hydroxyl group-containing polypropylene glycol (manufactured by Sanyo Chemical Industries, Ltd., “FF-2100”, number of hydroxyl groups: 2, number average molecular weight: 1000, group represented by formula (1) (primary hydroxyl group) The proportion of polyethylene glycol having: about 70 mol%, the proportion of polyethylene glycol having a secondary hydroxyl group: about 30 mol%)
A'3: Polyethylene glycol (made by Shin Nippon Rika Co., Ltd., "PEG-6000S", Number of hydroxyl groups: 2, Number average molecular weight: 8600, polyethylene glycol having a group (primary hydroxyl group) represented by Formula (1) Ratio: 100 mol%)

<Polyisocyanate (B)>
B1: Diphenylmethane diisocyanate (Tosoh Corp. "Millionate MT", number of isocyanate groups: 2)

Morpholine-based curing catalyst (C)
C1: 2,2'-dimorpholinodiethyl ether (manufactured by San-Apro, "UCAT 660 M")

  In addition, in Table 1, the numerical value in the parenthesis in the item of polyether polyol means the compounding quantity of a specific polyether polyol.

  Each characteristic of the reactive hot melt adhesive composition obtained by the Example and the comparative example was evaluated as follows. The results are shown in Table 2.

<Viscosity (melt viscosity)>
Melting of adhesive composition (sample amount 15 g) at a rotor rotational speed of 100 rpm (1 / s) at 120 ° C using a BH-HH type small amount rotational viscometer (made by Toki Sangyo Co., Ltd.) and a No. 4 rotor The viscosity was measured.

<Thermal stability>
The adhesive composition was sealed in a metal can and allowed to stand in an oven at 110 ° C. for 24 hours. The viscosity after heating is measured using a BH-HH small amount rotational viscometer (manufactured by Toki Sangyo Co., Ltd.) under the same conditions as the above-mentioned heating, and the viscosity increase rate after heating is determined based on the following equation. This was evaluated as thermal stability.
Viscosity increase rate after heating [%]
= (Viscosity after heating [Pa s] / viscosity before heating [Pa s]) x 100

<Adhesive strength>
Two rectangular plates (members) made of SUS (stainless steel) having short sides of 25 mm and long sides of 50 mm were prepared. The adhesive composition was heated and melted at 100 ° C. and applied at a position of 10 mm from the short side of the rectangular plate so as to be 25 mm in length parallel to the short side. After coating, a 100 μm thick polycarbonate film is used as a spacer, and the coated rectangular plate and another rectangular plate are bonded to each other, and the width of the adhesive layer made of the coated adhesive composition is adjusted to 2 mm. did. That is, an adhesive layer composed of an adhesive composition of 2 mm × 25 mm × 100 μm was sandwiched between two SUS rectangular plates and adhered, and this was used as a test piece. The obtained test piece was allowed to stand in a constant temperature bath at 25 ° C. and 50% RH (relative humidity) for 24 hours, and then the test piece was pulled in the shear direction, and the maximum load (shear adhesion) was evaluated as adhesion strength. .

  As shown in Table 2, the reactive hot melt adhesive compositions of Examples 1-9 containing a urethane prepolymer containing a specific polyether polyol and a morpholine based curing catalyst contain a urethane prepolymer containing a specific polyether polyol. In comparison with the reactive hot melt adhesive composition of Comparative Example 1 of Comparative Example 1 or the reactive hot melt adhesive composition of Comparative Example 2 containing no morpholine curing catalyst, the thermal stability and the adhesive strength were excellent. From these, it was confirmed that the reactive hot melt adhesive composition of the present invention has high adhesive strength even when it is applied to a member having excellent thermal stability and low moisture permeability.

Claims (4)

A urethane prepolymer having a polymer chain including a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and having an isocyanate group at an end of the polymer chain;
Morpholine curing catalyst,
Contains
Reactive hot melt adhesive composition containing the polyether polyol in which the said polyol has group represented by following formula (1).

  The reactive hot melt adhesive composition according to claim 1, wherein the content of the polyether polyol is 5 to 55 parts by mass with respect to 100 parts by mass of the polyol.   The reactive hot melt adhesive composition according to claim 1 or 2, wherein the polyether polyol is polyethylene glycol.   The reactive hot melt adhesive composition according to any one of claims 1 to 3, wherein the content of the morpholine-based curing catalyst is 0.1 to 0.9 parts by mass with respect to 100 parts by mass of the polyol. object.