TWI842947B - Moisture-curing polyurethane hot-melt resin composition, adhesive and laminate - Google Patents

Abstract

The problem to be solved by the present invention is to provide a moisture-hardening polyurethane resin composition having excellent adhesion to a blank (especially a hydrophobic blank). The present invention provides a moisture-hardening polyurethane hot-melt resin composition, which is characterized by containing a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) having an isocyanate group is a reaction product of a polyol (A) including a polyester polyol (a1) and a polyisocyanate (B), wherein the polyester polyol (a1) is a reaction product of a polyacid including adipic acid and a compound (x), wherein the compound (x) has a number average molecular weight of less than 500, has a branched structure, and has two to four hydroxyl groups. The compound (x) is preferably one or more selected from the group consisting of 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol and neopentyl glycol.

Description

Moisture-curing polyurethane hot-melt resin composition, adhesive and laminate

The present invention relates to a moisture-curing polyurethane resin composition, an adhesive and a laminate.

The moisture-permeable and waterproof functional clothing having both moisture-permeability and waterproofness is a structure formed by bonding a moisture-permeable film to a base material by an adhesive. As the adhesive, a urethane adhesive is generally used in terms of good adhesion to both the moisture-permeable film and the base material. In addition, among the urethane adhesives, the use of solvent-free moisture-curing polyurethane resin compositions has been gradually increasing due to the recent global solvent emission restrictions or residual solvent restrictions (for example, refer to Patent Document 1).

On the other hand, it is pointed out that the use of the blank material has become finer and more hydrophobic due to its high functionality, which in turn leads to poor adhesion with the adhesive. In the current moisture-curing polyurethane resin composition, there is currently no one that exhibits high adhesion, especially compared to the super hydrophobic blank material.

[Prior art literature]

[Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2017-202608

The problem to be solved by the present invention is to provide a moisture-curing polyurethane resin composition with excellent adhesion to blanks (especially water-repellent blanks).

The present invention provides a moisture-curing polyurethane hot-melt resin composition, which contains an isocyanate-containing urethane prepolymer (i), wherein the isocyanate-containing urethane prepolymer (i) is a reaction product of a polyol (A) containing a polyester polyol (a1) and a polyisocyanate (B), wherein the polyester polyol (a1) is a reaction product of a polyacid containing adipic acid and a compound (x), wherein the compound (x) has a number average molecular weight of less than 500, has a branched structure, and has two to four hydroxyl groups.

In addition, the present invention provides an adhesive containing the moisture-curing polyurethane resin composition. Furthermore, the present invention provides a laminate having at least a blank (i) and a cured product of the moisture-curing polyurethane resin composition.

The moisture-curing polyurethane hot-melt resin composition of the present invention does not contain a solvent and is an environmentally resistant material. In addition, the moisture-curing polyurethane hot-melt resin composition of the present invention has excellent adhesion to various blanks and also has excellent adhesion to water-repellent blanks.

The moisture-curing polyurethane hot-melt resin composition used in the present invention is a reaction product of a polyol (A) containing a specific polyester polyol and a polyisocyanate (B), and contains a urethane prepolymer (i) having an isocyanate group.

In order to obtain excellent adhesion to the blank, the polyol (A) must contain a polyester polyol (a1), which is a reaction product of a polybasic acid containing adipic acid and a compound (x) having a number average molecular weight of less than 500, a branched structure and two to four hydroxyl groups.

As the polyacid, adipic acid can be used alone, but other polyacids can also be used in combination. As the other polyacids, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, etc. can be used. These polyacids can be used alone or in combination of two or more. The usage rate of adipic acid in the polyacid is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more.

As the compound (x) having a number average molecular weight of less than 500, a branched structure and two to four hydroxyl groups, for example, 2-methyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,2-butanediol, 1,3-butanediol, 2-butyl-2-ethyl-1, 3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, 2-methyl-1,8-octanediol, trihydroxymethylpropane, etc. These compounds may be used alone or in combination of two or more. Among these, in terms of obtaining better adhesion to the blank, it is preferred to use one or more compounds selected from the group consisting of 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol and neopentyl glycol. Furthermore, the number average molecular weight of the compound (x) refers to the value calculated based on the chemical structure formula.

If necessary, other compounds having two or more hydroxyl groups may be used in combination with the compound (x). As the other compounds having two or more hydroxyl groups, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerol, trihydroxymethylpropane, bisphenol A or bisphenol F and their oxirane adducts, etc. These compounds may be used alone or in combination of two or more. The usage rate of the compound (x) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more in the total mass of the compound (x) and the other compounds having two or more hydroxyl groups.

The number average molecular weight of the polyester polyol (a1) is preferably in the range of 500 to 100,000, and more preferably in the range of 700 to 10,000, in order to obtain better adhesion to the blank and mechanical strength. The number average molecular weight of the polyester polyol (a1) refers to a value measured by gel permeation chromatography (GPC).

The polyol (A) must contain the polyester polyol (a1), but may contain other polyols as needed. As the other polyols, for example, other polyester polyols (a2), polycarbonate polyols, polyether polyols, polybutadiene polyols, polyacrylic polyols, etc. other than the polyester polyol (a1) can be used. These polyols can be used alone or in combination of two or more. Among them, in terms of obtaining better adhesion to the blank, it is preferred to use the other polyester polyol (a2). As for the usage rate of the polyester polyol (a1) in the polyol (A), in terms of obtaining better adhesion to the blank, it is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably in the range of 40% by mass to 60% by mass in the polyol (A).

As the other polyester polyol (a2), for example, a reaction product of a compound having two or more hydroxyl groups other than the compound (x) and a polybasic acid can be used.

As compounds having two or more hydroxyl groups other than the above compound (x), for example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerol, trihydroxymethylpropane, bisphenol A or bisphenol F and their alkylene oxide adducts can be used. These compounds can be used alone or in combination of two or more.

As the polyacid, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, etc. can be used. These polyacids can be used alone or in combination of two or more. Among them, phthalic acid (one or more compounds selected from the group consisting of phthalic acid, phthalic anhydride, isophthalic acid and terephthalic acid) is preferably used in terms of obtaining better adhesion to the blank.

The number average molecular weight of the polyester polyol (a2) is preferably in the range of 500 to 100,000, and more preferably in the range of 700 to 10,000, in order to obtain better adhesion to the blank and mechanical strength. The number average molecular weight of the polyester polyol (a2) is a value measured by gel permeation chromatography (GPC).

The usage rate of the polyester polyol (a2) is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably in the range of 40% by mass to 60% by mass in the polyol (A) in order to obtain better adhesion to the blank.

As the polyisocyanate (B), aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, xylene diisocyanate, phenyl diisocyanate, toluene diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylxylene diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more. Among these, aromatic polyisocyanate is preferred, and diphenylmethane diisocyanate is more preferred, in terms of obtaining better reactivity and adhesion to the blank.

The amount of the polyisocyanate (B) used is preferably in the range of 5% to 40% by mass, and more preferably in the range of 10% to 30% by mass, based on the total mass of the raw materials constituting the urethane prepolymer (i).

The urethane prepolymer (i) is obtained by reacting the polyol (A) with the polyisocyanate (B), and has an isocyanate group that can react with moisture in the air or in a substrate coated with a moisture-curing polyurethane hot-melt resin composition to form a cross-linked structure.

As a method for producing the urethane prepolymer (i), for example, the urethane prepolymer (i) can be produced by placing the polyisocyanate (B) in a reaction container containing the polyol (A) and reacting the polyisocyanate (B) under the condition that the isocyanate group of the polyisocyanate (B) is in excess relative to the hydroxyl group of the polyol (A).

When producing the urethane prepolymer (i), the equivalent ratio (isocyanate group/hydroxyl group) of the isocyanate group of the polyisocyanate (B) to the hydroxyl group of the polyol (A) is preferably in the range of 1.1 to 5, and more preferably in the range of 1.5 to 3, in order to obtain better adhesion to the blank.

The isocyanate group content (hereinafter referred to as "NCO%") of the urethane prepolymer (i) obtained by the above method is preferably in the range of 1.7 to 5, and more preferably in the range of 1.8 to 3, in order to obtain better adhesion. The NCO% of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with Japanese Industrial Standards (JIS) K1603-1: 2007.

The moisture-curing polyurethane hot-melt resin composition used in the present invention contains the urethane prepolymer (i) as an essential component, but other additives may also be used as needed.

As the other additives, for example, light-resistant stabilizers, hardening catalysts, adhesives, plasticizers, stabilizers, fillers, dyes, pigments, fluorescent brighteners, silane coupling agents, waxes, thermoplastic resins, etc. can be used. These additives can be used alone or in combination of two or more.

As mentioned above, the moisture-curing polyurethane hot-melt resin composition of the present invention does not contain a solvent and is an environmentally resistant material. In addition, the moisture-curing polyurethane hot-melt resin composition of the present invention has excellent adhesion to various blanks and also has excellent adhesion to water-repellent blanks.

Next, the laminate of the present invention will be described.

The laminate of the present invention comprises at least a blank (i) and a cured product of the moisture-curing polyurethane hot-melt resin composition.

As the blank (i), for example, the following fiber substrates can be used: polyester fiber, polyethylene fiber, nylon fiber, acrylic fiber, polyurethane fiber, acetate fiber, rayon fiber, polylactic acid fiber, cotton, linen, silk, wool, glass fiber, carbon fiber, non-woven fabrics, woven fabrics, knitted fabrics, etc. formed by blended fibers thereof; non-woven fabrics impregnated with resins such as polyurethane resin; non-woven fabrics further provided with a porous layer; resin substrates, etc.

In the present invention, the blank (i) exhibits excellent adhesion even if the blank is subjected to a water-repellent treatment (hereinafter referred to as a "water-repellent blank"). Furthermore, in the present invention, the "water-repellent" of the water-repellent blank means that the surface free energy obtained by the following calculation is 50 mJ/ ^m2 or less.

The contact angle of the measuring liquid (water and diiodomethane) on the blank (i) was measured using a contact angle meter ("DM500" manufactured by Kyowa Interface Science Co., Ltd.). Based on the results, the surface free energy of the blank (i) was calculated using the following formula (1).

(1+cosA)． γL/2=(γsd．γLd)1/2+(γsp．γLp)1/2

A: Contact angle of the measuring liquid on the blank (i)

γL: Surface tension of the measuring liquid

γLd: Dispersion force component of the surface free energy of the measurement liquid

γLp: Polar force component of the surface free energy of the measurement liquid

γsd: Dispersion force component of the surface free energy of the blank (i)

γsp: Polar force component of the surface free energy of the blank (i)

As a method for applying the moisture-curing polyurethane hot melt resin composition, for example, there can be cited methods using a roller coater, a scraper coater, a spray coater, a gravure roller coater, a notched wheel coater, a T-die coater, an applicator, a dispenser, etc.

After applying the moisture-curing polyurethane hot-melt resin composition, it is dried and cured by a known method.

The thickness of the cured product of the moisture-curing polyurethane hot-melt resin composition is, for example, in the range of 5μm to 300μm.

Furthermore, when the moisture-curing polyurethane hot-melt resin composition of the present invention is used as an adhesive for moisture-permeable and waterproof functional clothing, the moisture-curing polyurethane hot-melt resin composition is preferably intermittently coated by a gravure roller coating machine or a dispenser to bond the blank (i) to a known moisture-permeable film. The thickness of the cured product of the moisture-curing polyurethane hot-melt resin composition in the above case is, for example, in the range of 5μm to 50μm.

[Implementation example]

The present invention is described in more detail below using an embodiment.

[Implementation Example 1]

In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux cooler, 40 parts by mass of a polyester polyol (obtained by reacting adipic acid with 2-methyl-1,3-propanediol, number average molecular weight: 2,000, hereinafter referred to as "AA/2MPD") and 40 parts by mass of a polyester polyol (obtained by reacting phthalic anhydride, diethylene glycol and neopentyl glycol, number average molecular weight: 1,000, hereinafter referred to as "PA-based PEs (1)") were placed and dried under reduced pressure at 110°C to dehydrate until the moisture content became 0.05% by mass or less. Then, after cooling to 60°C, 27 parts by weight of diphenylmethane diisocyanate (hereinafter referred to as "MDI") was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a certain level, thereby obtaining a moisture-curing polyurethane hot-melt resin composition.

[Example 2]

A moisture-curing polyurethane hot-melt resin composition was obtained in the same manner as in Example 1 except that polyester polyol (obtained by reacting adipic acid with 3-methyl-1,5-pentanediol, number average molecular weight: 2,000, hereinafter referred to as "AA/3MPD") was used instead of the AA/2MPD.

[Implementation Example 3]

Instead of the AA/2MPD, a polyester polyol (obtained by reacting adipic acid with neopentyl glycol, number average molecular weight: 2,000, hereinafter referred to as "AA/NPG") was used. A moisture-curing polyurethane hot-melt resin composition was obtained in the same manner as in Example 1.

[Implementation Example 4]

A moisture-curing polyurethane hot-melt resin composition was obtained in the same manner as in Example 1 except that polyester polyol (obtained by reacting phthalic acid and ethylene glycol, number average molecular weight: 1,000, hereinafter referred to as "PA-based PEs (2)") was used instead of the PA-based PEs (1).

[Comparison Example 1]

In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux cooler, 40 parts by mass of polyester polyol (a reaction product of adipic acid, phthalic acid, terephthalic acid and ethylene glycol, number average molecular weight: 2,000, hereinafter referred to as "AA/PA/EG") and 40 parts by mass of polyester polyol (a reaction product of phthalic acid and 1,6-hexanediol, number average molecular weight: 2,000, hereinafter referred to as "PA/HG") were placed and dried under reduced pressure at 110°C to dehydrate until the moisture content became less than 0.05% by mass. Then, after cooling to 60°C, 21 parts by weight of MDI was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a certain level, thereby obtaining a moisture-curing polyurethane hot-melt resin composition.

[Method for determining number average molecular weight]

The number average molecular weight of the polyol used in the examples and comparative examples represents the value measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Co., Ltd.)

Column: Use the following columns manufactured by Tosoh Corporation by connecting them in series.

"TSKgel G5000" (7.8mmI.D.×30cm)×1

"TSKgel G4000" (7.8mm I.D. × 30cm) × 1 piece

"TSKgel G3000" (7.8mmI.D.×30cm)×1

"TSKgel G2000" (7.8mmI.D.×30cm)×1

Detector: RI (differential refractometer)

Column temperature: 40℃

Solvent: Tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Injection volume: 100μL (sample concentration is 0.4 mass% tetrahydrofuran solution)

Standard sample: Use the following standard polystyrene to prepare the standard curve.

(Standard Polystyrene)

"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[Evaluation method of adhesion to blank]

The moisture-curing polyurethane hot-melt resin composition obtained in the examples and comparative examples was melted at 100°C and coated on a moisture-permeable film (VENTEX manufactured by Gapyeong Co., Ltd.) using a gravure roll coater (40 L/inch, depth 130, adhesion amount: 10 g/m ² ), and then laminated with the following three types of blanks, and left in an environment of temperature 23°C and humidity 50% for 2 days to obtain processed fabrics.

Blank (1): Non-hydrophobic blank (surface free energy: more than 50mJ/m ² )

Blank (2): Water-repellent blank (surface free energy: range of 10mJ/m ² ~50mJ/m ² )

Blank (3): Superhydrophobic blank (surface free energy: less than 10mJ/m ² )

The processed fabric was cut into 1 inch width and the peel strength (N/inch) between the moisture permeable film and the blank was measured using the "Autograph AG-1" manufactured by Shimadzu Corporation.

It can be seen that the moisture-curing polyurethane hot-melt resin composition of the present invention has good adhesion to the blank. In particular, it can be seen that it also has excellent adhesion to the hydrophobic blank or super hydrophobic blank.

On the other hand, in Comparative Example 1, a polyester polyol which is a reaction product of adipic acid and a linear diol is used instead of polyester polyol (a1), and the adhesion to the super hydrophobic base material is poor.

Claims (6)

A moisture-curing polyurethane hot-melt resin composition, characterized in that it contains an isocyanate-containing urethane prepolymer (i), wherein the isocyanate-containing urethane prepolymer (i) is a reaction product of a polyol (A) containing a polyester polyol (a1) and other polyester polyols (a2) and a polyisocyanate (B), wherein the polyester polyol (a1) is a reaction product of a polyacid containing adipic acid and a compound (x), wherein the compound (x) has a number average molecular weight of less than 500 and has a branched structure and has two to four hydroxyl groups, wherein the usage rate of the polyester polyol (a1) in the polyol (A) is 40% to 60% by mass, and the usage rate of the other polyester polyols (a2) in the polyol (A) is 40% to 60% by mass. The moisture-curing polyurethane hot-melt resin composition as described in claim 1, wherein the compound (x) is one or more selected from the group consisting of 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol and neopentyl glycol. A moisture-curing polyurethane hot-melt resin composition as described in claim 1 or 2, wherein the other polyester polyol (a2) uses phthalic acid as a raw material. An adhesive characterized by containing a moisture-curing polyurethane hot-melt resin composition as described in any one of claims 1 to 3. A laminated body characterized by having at least a blank and a cured product of a moisture-curing polyurethane hot-melt resin composition as described in any one of claims 1 to 3. A laminate as described in claim 5, wherein the blank is a water-repellent blank.