阅读说明：本技术 湿固化型热熔粘合剂 (Moisture-curable hot-melt adhesive ) 是由 松田健二 高森爱 早川正 于 2018-05-17 设计创作，主要内容包括：本发明提供了一种初始粘合强度、固化后粘合强度和耐热性等具有优异平衡的湿固化型热熔粘合剂,以及用所述湿固化型热熔粘合剂粘结的层状产品。解决这一问题的方式：一种湿固化型热熔粘合剂,其包含在末端处具有异氰酸酯基的氨基甲酸酯预聚物(A),基于苯乙烯的嵌段共聚物(B),和增粘树脂(C),其中所述基于苯乙烯的嵌段共聚物(B)包含具有10-35重量％苯乙烯含量的基于苯乙烯的嵌段共聚物(B1)和具有40-70重量％苯乙烯含量的基于苯乙烯的嵌段共聚物(B2)。(The present invention provides a moisture-curable hot-melt adhesive having an excellent balance of initial adhesive strength, adhesive strength after curing, heat resistance and the like, and a layered product bonded with the moisture-curable hot-melt adhesive. Means for solving this problem: a moisture-curable hot melt adhesive comprising a urethane prepolymer (a) having an isocyanate group at a terminal, a styrene-based block copolymer (B), and a tackifying resin (C), wherein the styrene-based block copolymer (B) comprises a styrene-based block copolymer (B1) having a styrene content of 10 to 35% by weight and a styrene-based block copolymer (B2) having a styrene content of 40 to 70% by weight.)

1. A moisture-curable hot melt adhesive comprising

A urethane prepolymer (A) having an isocyanate group at the terminal,

a styrene-based block copolymer (B), and

a tackifying resin (C), wherein

The styrene-based block copolymer (B) includes a styrene-based block copolymer (B1) having a styrene content of 10 to 35% by weight and a styrene-based block copolymer (B2) having a styrene content of 40 to 70% by weight.

2. The moisture-curable hot melt adhesive according to claim 1, wherein (B1) is a styrene-isoprene based block copolymer and (B2) is a styrene-isoprene based block copolymer.

3. The moisture-curable hot melt adhesive according to claim 1 or 2, wherein the moisture-curable hot melt adhesive comprises 25 to 64 parts by weight of (a), 10 to 40 parts by weight of (B1), and 10 to 40 parts by weight of (B2), based on 100 parts by weight of (a) and (B) in total.

4. The moisture-curable hot melt adhesive according to any one of claims 1 to 3, wherein the moisture-curable hot melt adhesive comprises 60 to 110 parts by weight of the tackifying resin (C) based on 100 parts by weight of (A) and (B) in total.

5. The moisture-curable hot melt adhesive according to any one of claims 1 to 4, wherein the styrene-based block copolymer (B2) is a triblock copolymer.

6. A layered product comprising a substrate, an adhesive layer formed on a surface of the substrate, and an adherend bonded to a surface of the adhesive layer, wherein

The adhesive layer consists of the moisture-curable hot melt adhesive according to any one of claims 1 to 5.

Technical Field

The present invention relates to a moisture-curable hot melt adhesive.

Background

Hot melt adhesives are used in various fields, such as the field of building interior materials (or building materials) and the field of electronic materials. Moisture-curable hot melt adhesives are attracting attention from the viewpoint of being less susceptible to external factors and being easy to use for a long period of time.

Examples of the moisture-curable hot melt adhesive include adhesives comprising urethane prepolymers having isocyanate groups at the terminals. At least one of the substrate and the adherend (adhesive) is coated with a moisture-curable hot-melt adhesive which is usually in a heated and melted state, and the moisture-curable hot-melt adhesive is cooled and cured, thereby preliminarily bonding together. Then, the isocyanate group is crosslinked with moisture in the air, and the molecular weight of the urethane prepolymer is increased by moisture curing, thereby improving adhesive strength, heat resistance, and the like.

One of the properties required for moisture-curable hot melt adhesives is initial bond strength. In order to improve the initial adhesive strength, a tackifying resin is mixed in a moisture-curable hot melt adhesive to improve initial wettability (wettability) on a substrate, or a thermoplastic resin is mixed in a hot melt adhesive to improve initial cohesion, or the like.

However, the tackifying resin and the thermoplastic resin are not always sufficiently compatible with urethane prepolymer, which is a main component of the moisture-curable hot melt adhesive.

Further, there are problems in handling because the time (open time) taken until the moisture-curable hot-melt resin is cured after coating is too short, handling is difficult, and because the viscosity of the adhesive becomes too high, coating is difficult.

Each of patent documents 1 to 3 discloses a moisture-curable hot melt adhesive comprising a urethane prepolymer and a thermoplastic resin. All references to moisture-curable hot melt adhesives include urethane prepolymers and styrene-based copolymers. The disclosures of patent documents 1 to 3 will be specifically described below.

Patent document 1 discloses a reactive hot melt adhesive composition mainly composed of a urethane prepolymer and a thermoplastic rubber composition (claim 1). In the moisture-curable hot melt adhesive of patent document 1, by preparing a urethane polymer using a prepolymer of a long-chain polyether having 6 or more carbons, the compatibility with a thermoplastic rubber composition is improved, thereby providing a reactive hot melt adhesive composition having excellent compatibility, moisture curability, and adhesiveness.

Patent document 1 discloses a styrene-ethylene-butylene-styrene (SEBS) block copolymer (example 1), a urethane prepolymer, a styrene-butadiene-styrene (SBS) block copolymer (comparative example 1), and the like as a thermoplastic rubber.

Patent document 2 discloses that in a reactive hot melt adhesive composition containing a urethane prepolymer, a styrene-based block copolymer rubber, and the like, initial adhesion is improved without significant reduction in adhesion at 50 to 60 ℃ by using a polyester polyol as a polyether component for synthesizing the urethane prepolymer. As the styrene-based copolymer rubber, an SBS block copolymer (example 1), an SEBS block copolymer (example 2), and the like are disclosed in document 2.

Document 3 discloses that in a reactive hot melt type adhesive composed mainly of a urethane prepolymer and a thermoplastic rubber component, compatibility with the thermoplastic rubber component becomes sufficient, and toughness and weather resistance (including non-yellowing) are improved by using a saturated hydrocarbon polyol having hydroxyl groups at both ends. In table 1 of patent document 3, a styrene-isoprene-styrene (SIS) block copolymer is disclosed as a thermoplastic rubber component. The SIS is mixed in an amount of 19 to 35 parts by weight based on 100 parts by weight of the urethane prepolymer and the SIS in total.

In the moisture-curable hot melt adhesives of patent documents 1 and 2, the balance between initial adhesive strength and heat resistance is poor. In the moisture-curable hot melt adhesive of document 3, the initial adhesive strength is extremely poor.

When the amount of the tackifier resin added is adjusted to improve the initial adhesive strength of the moisture-curable hot melt adhesive, the adhesive strength after curing is deteriorated. As described above, it is difficult to prepare a moisture-curable hot melt adhesive having an excellent balance of various properties. However, there is a consumer need for a moisture-curable hot melt adhesive with an excellent balance of properties.

Therefore, recently, there is an urgent need to develop a moisture-curable hot melt adhesive having an excellent balance among initial adhesive strength, adhesive strength after curing, and heat resistance.

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a moisture-curable hot-melt adhesive and a layered product bonded with the moisture-curable hot-melt adhesive.

Means for solving the technical problem

The present invention provides a moisture-curable hot melt adhesive comprising

A urethane prepolymer (A) having an isocyanate group at the terminal,

a styrene-based block copolymer (B), and

a tackifying resin (C), wherein

The styrene-based block copolymer (B) includes a styrene-based block copolymer (B1) having a styrene content of 10 to 35% by weight and a styrene-based block copolymer (B2) having a styrene content of 40 to 70% by weight.

In one embodiment, (B1) is a styrene-isoprene based block copolymer and (B2) is a styrene-isoprene based block copolymer.

In one embodiment, the moisture-curable hot melt adhesive comprises 25 to 64 parts by weight of (a), 10 to 40 parts by weight of (B1), and 10 to 40 parts by weight of (B2), based on 100 parts by weight of (a) and (B) in total.

In one embodiment, the moisture-curable hot melt adhesive comprises 60 to 110 parts by weight of a tackifying resin (C) based on 100 parts by weight of (a) and (B) in total.

In one embodiment, the styrene-based block copolymer (B2) is a triblock copolymer.

The present invention also provides a layered product comprising a substrate, an adhesive layer formed on a surface of the substrate, and an adherend bonded to a surface of the adhesive layer, wherein the adhesive layer is composed of any of the moisture-curable hot-melt adhesives.

Effects of the invention

In the moisture-curable hot melt adhesive of the present invention, the initial adhesive strength, heat resistance and adhesive strength after curing are improved in a balanced manner. In particular, the initial adhesive strength is excellent in a wide range of 5 ℃ to 35 ℃, and exhibits excellent initial adhesive strength at all temperatures including normal temperature (spring and summer), low temperature (winter) and high temperature (summer).

The moisture-curable hot melt adhesive of the present invention has an excellent balance of properties, and is applied to various substrates regardless of seasons and cold and warm areas. This can therefore contribute to the efficient production of a wide variety of layered products.

Detailed Description

First, technical terms used in the present application are described.

The "open time" refers to a time from when a melted moisture-curable hot-melt adhesive is applied to an adherend until the adhesive loses fluidity and thus the adhesive cannot wet the surface of the adherend.

"initial bond strength" refers to the bond strength when the temperature of a moisture-curable hot melt adhesive is lowered to cause the adhesive to cure after melting and applying the adhesive to an adherend. The initial adhesive strength is affected by wettability and aggregating power. Higher initial bond strengths are desirable.

"wettability" can be measured by the size of an angle (α) formed by the ends of a heated and melted moisture-curable hot-melt adhesive and a substrate (solid) when the melted adhesive is brought into contact with the substrate. As α decreases, wettability becomes greater and adhesion is facilitated.

"cohesion force" refers to a force caused by interaction between molecules in an adhesive, which occurs during cooling after applying a moisture-curable hot-melt adhesive that is heated and melted using an applicator.

The moisture-curable hot melt adhesive of the present invention is described below.

The moisture-curable hot melt adhesive of the present invention comprises a urethane prepolymer (a) having an isocyanate group at a terminal, a styrene-based block copolymer (B), and a tackifying resin (C), wherein the moisture-curable hot melt adhesive comprises 25 to 64 parts by weight of (a) based on 100 parts by weight of (a) and (B) in total.

In the present application, the moisture-curable hot melt adhesive is also simply referred to as "hot melt adhesive".

The components included in the moisture-curable hot melt adhesive of the present application will be described below.

< urethane prepolymer having terminal isocyanate group (A) >

The moisture-curable hot melt adhesive of the present invention comprises a urethane prepolymer (a) having a terminal isocyanate group (hereinafter also referred to as "component (a)"). Urethane polymers having terminal isocyanate groups are generally understood as "urethane prepolymers". The urethane prepolymer having "terminal isocyanate group" is not particularly limited as long as the desired moisture-curable hot melt adhesive can be obtained.

Such urethane prepolymers are obtained by reacting a polyol and an isocyanate compound according to a known method.

In the present application, the "polyol" is not particularly limited as long as the desired urethane prepolymer can be obtained. Known polyols commonly used for the preparation of polyurethanes can be used. As the polyol, preferred is a polyol having a functional group number of 1 to 3, particularly a bifunctional polyol, preferably a diol. The polyhydric alcohols may be used alone or in combination. Examples of diols include low molecular weight diols such as ethylene glycol, 1-methyl glycol, 1-ethyl glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, heptylene glycol, octylene glycol, nonanediol, decanediol, neopentyl glycol, 2-methyl-1, 3-propanediol, cyclohexanedimethanol, and 2, 4-dimethyl-1, 5-pentanediol. At least one of ethylene glycol, butanediol, hexanediol, octanediol, and decanediol is preferable. These diols may be used alone or in combination.

Examples of "polyols" in the present invention also include polyether polyols, polyester polyols, and the like.

Examples of the polyester polyol include, for example, polyoxytetramethylene glycol (PTMG), polypropylene oxide glycol (PPG), polyethylene oxide glycol (PEG), and the like. Polypropylene oxide glycol is particularly preferred as the polyether polyol.

In the present invention, aromatic polyester polyols and aliphatic polyester polyols may be exemplified as the polyester polyol.

The aromatic polyester polyol is preferably obtained by reacting an aromatic carboxylic acid and a diol. For example, as the aromatic polycarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, hexahydroisophthalic acid, and the like are exemplified. These may be used alone, or two or more kinds may be used in combination. Polyalkylene phthalates, polyalkylene isophthalates and polyalkylene terephthalates each having terminal OH groups may be cited as examples of the aromatic polyester polyol. As the aromatic polyester polyol, a polyalkylene phthalate having a terminal OH group is particularly preferable.

The aliphatic polyester polyol is obtained by reacting an aliphatic carboxylic acid and a diol. For example, as the aliphatic carboxylic acid, adipic acid, sebacic acid, azelaic acid, decamethylene dicarboxylic acid, and the like are exemplified. These may be used alone, or two or more kinds may be used in combination. Polyhexamethylene adipate (PHMA) and polybutylene adipate (PBA), each having a terminal OH group, may be exemplified as the aliphatic polyester polyol. As the aliphatic polyester polyol, polyhexamethylene adipate having a terminal OH group is particularly preferable.

In the present invention, examples of particularly preferred embodiments of the polyol include aliphatic polyester polyols. The aliphatic polyester polyol may be used alone or in combination of two or more different types.

The number average molecular weight of the polyol is not particularly limited, and is preferably 1,000 to 7,000. In the present application, the weight average molecular weight or the number average molecular weight is determined by Gel Permeation Chromatography (GPC) by converting the molecular weight using a calibration curve with monodisperse molecular weight polystyrene as a standard substance.

In the present invention, the isocyanate compound is not particularly limited as long as a desired urethane prepolymer can be obtained, and those used for conventionally producing polyurethanes can be used. The isocyanate compound preferably has 1 to 3 isocyanate groups per molecule on average, and particularly preferably is a bifunctional isocyanate compound, so-called diisocyanate compound. The isocyanate compound may be used alone, or two or more kinds may be used in combination.

Examples of the "isocyanate compound" include ethylene diisocyanate (ethylisopyanate), ethylene diisocyanate (ethylidene diisocyanate), propylene diisocyanate, butylene diisocyanate (butylene diisocyanate), hexamethylene diisocyanate, toluene diisocyanate, cyclopentylene-1, 3-diisocyanate, cyclohexylene-1, 4-diisocyanate, cyclohexylene-1, 2-diisocyanate, 4' -diphenylmethane diisocyanate, 2' -diphenylpropane-4, 4' -diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, xylylene diisocyanate (xylylene diisocyanate), 1, 4-naphthylene diisocyanate, 1, 5-naphthylene diisocyanate, diphenyl-4, 4' -diisocyanate, azobenzene-4, 4' -diisocyanate, diphenylsulfone-4, 4' -diisocyanate, dichlorohexamethylene diisocyanate, furfurylidene diisocyanate, 1-chlorobenzene-2, 4-diisocyanate, and the like. These isocyanate compounds may be used alone or in combination.

When preparing the "urethane prepolymer" according to the present invention, monohydric alcohols and monoisocyanates may be used, and trifunctional polyols and trifunctional isocyanates may be used, as long as the desired urethane prepolymer is obtained. Preferably, however, at least a difunctional polyol (diol) and a difunctional isocyanate (diisocyanate compound) are used for the preparation. More preferably, the "urethane prepolymer" is prepared by reacting the bifunctional polyol with the bifunctional isocyanate compound from the viewpoint of thermal stability of the available moisture-curable hot melt adhesive and easy control of the preparation method (and the preparation process thereof).

To prepare a urethane prepolymer having a terminal isocyanate group (a), a polyol and an isocyanate compound are mixed so that the lower limit of the molar ratio of NCO groups and OH groups (NCO/OH) is preferably 1.3 or more, more preferably 2 or more, and the upper limit thereof is preferably 3 or less. Further, it is preferable to use about 2mol (about 1.8mol to 2.3mol) of the bifunctional isocyanate based on 1mol of the bifunctional polyol, because the desired urethane prepolymer can be prepared relatively easily.

< (B) styrene-based block copolymer >

The moisture-curable hot melt adhesive of the present invention comprises a styrene-isoprene based block copolymer (B) (hereinafter also referred to as "component (B)"). The styrene-based block copolymer (B) is a copolymer obtained by block copolymerization of styrene as a vinyl aromatic hydrocarbon and a conjugated diene compound, and is generally a resin composition comprising a product composed of a styrene block and a conjugated diene compound block.

"conjugated diene compound" means a diene compound having at least one pair of conjugated double bonds. Specific examples of the "conjugated diene compound" may include 1, 3-butadiene, 2-methyl-1, 3-butadiene (or isoprene), 2, 3-dimethyl-1, 3-butadiene, 1, 3-pentadiene and 1, 3-hexadiene. In particular, 1, 3-butadiene and 2-methyl-1, 3-butadiene are preferable. These conjugated diene compounds may be used alone or in combination.

The thermoplastic block copolymer (B) according to the present invention may be an unhydrogenated product or a hydrogenated product.

Specific examples of "unhydrogenated products of the styrene-based block copolymer (B)" include those in which the conjugated diene compound blocks are not hydrogenated.

Specific examples of "the hydrogenated product of the styrene-based block copolymer (B)" include block copolymers in which the conjugated diene compound block is completely or partially hydrogenated.

The ratio at which the "hydrogenated product of the styrene-based block copolymer (B)" is hydrogenated can be expressed as "hydrogenation ratio". The "hydrogenation rate" of the "hydrogenation product of the styrene-based block copolymer (B)" means a ratio of double bonds converted into saturated hydrocarbon bonds by hydrogenation with respect to all aliphatic double bonds included in the conjugated diene compound block. The "hydrogenation rate" can be measured by an infrared spectrophotometer, a nuclear magnetic resonance spectrometer, or the like.

For example, a styrene-isoprene block copolymer ("SIS") and a styrene-butadiene block copolymer ("SBS") may be specifically exemplified by "unhydrogenated product of the styrene-based block copolymer (B").

The styrene-ethylene/propylene-styrene block copolymer (also referred to as "SEPS"), the styrene-ethylene/butylene-styrene block copolymer (also referred to as "SEBS"), and the like can be specifically exemplified by "a hydrogenated product of the styrene-based block copolymer (B)".

The styrene-based block copolymer (B) may be of the radial type, linear type or triblock type as long as the object of the present invention is not impaired.

In the present invention, the styrene-based block copolymer (B) preferably includes a styrene-based block copolymer having a styrene content of 15% by weight or more, and particularly preferably includes a styrene-based block copolymer (B1) having a styrene content of 15 to 35% by weight, and a styrene-based block copolymer (B2) having a styrene content of 40 to 60% by weight.

By including (a) and (B) in the hot melt adhesive of the present invention, the balance between the initial adhesive strength, the adhesive strength after curing, and the heat resistance becomes more excellent.

In the present invention, more preferably, (B1) includes a styrene-isoprene based block copolymer, and (B2) includes a styrene-isoprene based block copolymer.

In the present application, "styrene content" means the ratio of styrene blocks contained in the "styrene-based block copolymer (B)".

In the present invention, the styrene-based block copolymer (B1) having a styrene content of 15 to 35% by weight preferably has a diblock content of 30 to 70% by weight, and most preferably 35 to 60% by weight.

In the present invention, the styrene-based block copolymer (B2) having a styrene content of 40 to 70% by weight preferably has a diblock content of less than 40% by weight, particularly preferably not more than 30% by weight, and most preferably 0% by weight. The styrene-based block copolymer (B2) having a diblock content of 0% by weight became a triblock copolymer.

In the present application, the "diblock content" refers to the ratio of the styrene-conjugated diene compound block copolymer contained in (B). The diblock is represented by the following formula (1):

[ chemical formula 1]

S-E(1)

In the formula (1), S is a styrene block and E is a conjugated diene compound block.

Commercially available products can be used as the styrene-based block copolymer (B) of the present invention.

For example, as (B1), Asaprene T432 produced by Asahi Kasei Corporation, which is a styrene-butadiene-styrene block copolymer; quintac SL-165 (manufactured by ZEON Corporation), Vector4411A (manufactured by Dexco Corporation), Vector 4211A (manufactured by Dexco Corporation), Quintac 3270 (manufactured by ZEON Corporation), Quintac 3460 (manufactured by ZEON Corporation), Quintac 3433N (manufactured by ZEON Corporation), Quintac 3450 (manufactured by ZEON Corporation), etc., which are styrene-isoprene-styrene block copolymers.

(B2) Examples of (b) include Asaprene T439 (manufactured by Asahi Kasei Chemicals Corporation), which is a styrene-butadiene-styrene block copolymer; clayton D1162 (manufactured by Clayton Corporation), Quintac 3390 (manufactured by ZEON CORPORATION) and Quintac SL-168 (manufactured by Zeon CORPORATION), which are styrene-isoprene-styrene block copolymers.

The respective components of these commercial products may be used each alone or in combination of two or more thereof.

< tackifying resin (C) >

The moisture-curable hot melt adhesive according to the present invention comprises a tackifying resin (C) (hereinafter also referred to as "component (C)"). The tackifier resin (C) is not particularly limited, and is generally used, and can provide the moisture-curable hot melt adhesive for the purpose of the present invention.

For example, examples of the tackifying resin (C) may include: natural rosin, modified rosin, hydrogenated rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, pentaerythritol ester of hydrogenated rosin, copolymer of natural terpene, three-dimensional polymer of natural terpene, hydrogenated derivative of copolymer of hydrogenated terpene, polyterpene resin, hydrogenated derivative of phenol-based modified terpene resin, aliphatic petroleum hydrocarbon resin, hydrogenated derivative of aliphatic petroleum hydrocarbon resin, aromatic petroleum hydrocarbon resin, hydrogenated derivative of aromatic petroleum hydrocarbon resin, cycloaliphatic petroleum hydrocarbon resin, and hydrogenated derivative of cycloaliphatic petroleum hydrocarbon resin. These tackifying resins may be used alone or in combination.

The tackifying resin may be a modified product of these resins (for example, a modified rosin having a chemical bond and a functional group) as long as the object of the present invention is achieved. The "modified rosin" in the present application means a rosin having an amino group, a maleic acid group, an epoxy group, a hydroxyl group, a urethane bond, an amide bond, or the like.

Commercially available products can be used as the tackifier resin (C). Examples of such commercially available products include, for example, MARUZENPETROCEMICAL CO., MARUKACLEAR H (trade name) by LTD., YASUHARA CHEMICAL CO., CLEaron K100 (trade name) by LTD, CLEaron K4090 (trade name) and CLEaron K4100 (trade name), Arakawa CHEMICAL Industries, Arkon M-100 (trade name) by LTD, Idemitsu Kosan CO., I-Marv S110 (trade name) by LTD, T-REZ HA103 (trade name) by Tonen General Sekiyu K.K, T-REZ HA125 (trade name) and T-REZ HC103 (trade name), Eastman CHEMICAL CO., Regalite R7100 (trade name) by LTD. These commercially available tackifying resins may be used alone or in combination.

In the moisture-curable hot melt adhesive of the present invention, the contents of the components (a), (B) and (C) may be defined according to 100 parts by weight of the total weight of the urethane prepolymer (a) having an isocyanate group at a terminal and the styrene-isoprene based block copolymer (B). Namely, they are as follows:

a component (A): usually 25 to 64 parts by weight, preferably 30 to 63 parts by weight, more preferably 50 to 60 parts by weight;

component (B1): usually 5 to 40 parts by weight, preferably 10 to 35 parts by weight.

Component (B2): usually 5 to 40 parts by weight, preferably 20 to 35 parts by weight; and

a component (C): usually 60 to 110 parts by weight, preferably 70 to 100 parts by weight, more preferably 80 to 90 parts by weight.

By including the respective components in the above ratio, the balance between the initial adhesive strength, the heat resistance, and the adhesive strength after curing becomes excellent.

< plasticizer (D) >

The moisture-curable hot melt adhesive of the present invention preferably includes a plasticizer (D) in addition to the components (a) to (C). The plasticizer (D) keeps the viscosity of the moisture-curable hot melt adhesive low to some extent while improving the compatibility of the components (a) to (C). Since the moisture-curable hot-melt adhesive has a low viscosity, it is excellent in coating properties and improves wettability on an adherend. Therefore, the initial adhesive strength is improved.

In the present invention, the plasticizer (D) is not particularly limited as long as it is generally used, and the moisture-curable hot melt adhesive which is the object of the present invention can be obtained.

Examples of the plasticizer (D) may include paraffin-based oil, naphthenic-based oil and aromatic-based oil, dioctyl phthalate, dibutyl phthalate, dioctyl adipate and mineral spirits.

As the plasticizer (D), a commercially available product can be used. For example, examples thereof may include White Oil bloom 350 (trade name) manufactured by Kukdong Oil & Chemicals co., ltd.; IDEMITSU KOSAN CO., produced by LTD. by Diana Freesia S32 (trade name), Diana Process Oil PW-90 (trade name) and DN Oil KP-68 (trade name); enerper M1930 (trade name) manufactured by BP Chemicals, inc; kaydol (trade name) manufactured by Crompton Corporation; primol 352 (trade name) by ESSO corp; IDEMITSU KOSAN co., ltd. Process Oil NS 100; and KN 4010 (trade name) produced by PetroChina Company Limited. These plasticizers (D) may be used alone or in combination.

The moisture-curable hot melt resin of the present invention may further include other additives. The "additives" are not particularly limited as long as they are generally used for moisture-curable hot melt adhesives, and can be used for the moisture-curable hot melt adhesive of the present invention. Examples of such additives may include, for example, plasticizers, antioxidants, pigments, light stabilizers, flame retardants, catalysts, waxes, and the like.

For example, as the "antioxidant", a phenol-based antioxidant, a phosphite-based antioxidant, a thioether-based antioxidant, an amine-based antioxidant, and the like can be exemplified.

For example, as the "pigment", titanium oxide, carbon black, and the like can be exemplified.

Examples of the "light stabilizer" include benzotriazole, hindered amine, benzoate, benzotriazole, and the like.

For example, as the "flame retardant", halogen-based flame retardants, phosphorus-based flame retardants, antimony-based flame retardants, metal hydroxide-based flame retardants, and the like can be exemplified.

As the "catalyst", metal-based catalysts such as tin-based catalysts (trimethyltin laurate, trimethyltin hydroxide, dibutyltin dilaurate, dibutyltin maleate, and the like), lead-based catalysts (lead oleate, lead naphthenate, lead octenoate, and the like), and other metal-based catalysts (metal naphthenate salts, such as cobalt naphthenate), and amine-based catalysts such as triethylenediamine, tetramethylethylenediamine, tetramethylhexamethylenediamine, diazabicylene, dialkylaminoalkylamine, and the like are exemplified.

For example, as "wax", waxes such as paraffin wax and microcrystalline wax are exemplified.

In the method for producing the moisture-curable hot melt adhesive of the present invention, the mixing order of the respective components, the mixing method, and the like are not particularly limited as long as the method includes mixing the respective components and additives according to need. One or both of the polyol and the isocyanate compound for obtaining the urethane prepolymer (a) having a terminal isocyanate group (component (a)) and the other components (B) and (C) may be mixed simultaneously; or after preparing a urethane prepolymer having a terminal isocyanate group by reacting a polyol and an isocyanate compound, the resultant product may be mixed with other components.

The moisture-curable hot melt adhesive of the present invention can be prepared by heating, melting and mixing the components. For example, the above components are added to a melt mixer equipped with a stirrer, and the mixture is heated and mixed to carry out preparation.

The moisture-curable hot melt adhesive of the present invention obtained in this way is a reactive hot melt adhesive which is solid at room temperature. The reactive hot melt adhesive can be used in a known manner. The moisture-curable hot-melt adhesive is generally heated and melted for use.

< layered product >

The layered product of the present invention comprises the above moisture-curable hot melt adhesive. Layered products are made by laminating an "adherend" to the surface of a "substrate". When a layered product is prepared, the moisture-curable hot melt adhesive may be applied to the substrate side, the adhesive body side, or both sides. Herein, the materials of the adherend and the substrate, the forms thereof, and the like may be the same or different.

The "substrate" is not particularly limited, and the following may be exemplified:

wood materials such as plywood (e.g., lauan plywood), Medium Density Fiberboard (MDF), particleboard, solid wood, wood fiberboard;

inorganic materials such as cement boards, gypsum boards, and Autoclaved Lightweight Concrete (ALC); and

plastic materials such as polyethylene terephthalate, polycarbonate, polyurethane, polyethylene and polypropylene.

The form of the "substrate" is also not particularly limited, and it may be a molded resin type, a film type or a sheet type.

The "adherend" may be those conventionally used and is not particularly limited. Specifically, examples may be a film, a sheet, and the like.

The film may be colorless or colored, and may also be transparent or opaque. For example, a film made of polyolefin resin, polyester resin, acetate resin, polystyrene resin, vinyl chloride resin, or the like may be exemplified. For example, as the polyolefin resin, polyethylene and polypropylene are exemplified. For example, as the polyester resin, polyethylene terephthalate may be exemplified.

The adhesive body may be a decorative sheet. The following may be exemplified as the decorative sheet:

sheets made of plastic materials such as hard or semi-hard vinyl chloride resins, polyolefin resins, and polyester resins;

a wood board obtained by cutting wood into sheets; and

decorative paper subjected to various decorative printing.

The layered product of the present invention can be used specifically for various purposes such as building materials, furniture, electronic materials and automobiles.

No special equipment is required to prepare the layered product. The layered product can be produced using known production equipment including a conveyor, a coater, a press, a heater, and a cutter.

For example, a layered product can be prepared by the following procedure. The moisture-curable hot melt adhesive of the present invention is applied to a substrate or an adherend by an applicator while the substrate and the adherend are conveyed by a conveyor. The temperature during the coating process is controlled to a predetermined temperature by a heater. The adherend and the substrate were laminated to each other by a moisture-curable hot-melt adhesive by lightly pressing the adherend against the substrate using a press. Then, the laminated adherend and substrate were left to cool and conveyed by a conveyor as they were, thereby curing the moisture-curable hot melt adhesive. Thereafter, the substrate laminated with the adhesive body is cut into an appropriate size with a cutter.

The moisture-curable hot melt adhesive of the present invention has high initial adhesive strength even after curing and also has excellent heat resistance, thereby efficiently producing the layered product of the present invention to give products excellent in various properties.