JP7183758B2 - Moisture-curable polyurethane hot-melt resin composition, adhesive, and article - Google Patents

Description

The present invention relates to moisture-curable polyurethane hot-melt resin compositions, adhesives, and articles.

In the field of interior construction, deterioration (peeling, etc.) of processed products over time has become a problem, and adhesives with high durability, especially high resistance to hydrolysis, are required.

Moisture-curable polyurethane hot-melt resin compositions are widely used as adhesives in the field of interior construction as they are moisture-cured to provide excellent final adhesive strength. In the moisture-curable polyurethane hot-melt resin composition, as a method for improving the hydrolysis resistance, the use of polycarbonate polyol, which has excellent durability, is mainly used (see, for example, Patent Document 1).

As the polycarbonate polyol, solid and liquid types are commercially available. However, conventional solid polycarbonate polyols are hard and have low adhesion to substrates. There is a problem that the adhesive strength to general-purpose substrates decreases, and liquid polycarbonate polyols have excellent adhesion to substrates, but have a problem that the initial adhesive strength immediately after lamination is low.

JP-A-2016-785

The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt resin composition that is excellent in initial adhesive strength, final adhesive strength, and hydrolysis resistance.

The present invention provides a moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reactant of a polyol (a) and a polyisocyanate (b), wherein the polyol (a) is Provided is a moisture-curable polyurethane hot-melt resin composition containing a polycarbonate polyol (a1) made from a glycol compound (x) having a branched structure.

The present invention also provides an adhesive characterized by containing the moisture-curable polyurethane hot-melt resin composition, and an article characterized by bonding with the adhesive.

The moisture-curable polyurethane hot-melt resin composition of the present invention is excellent in initial adhesive strength, final adhesive strength, and hydrolysis resistance.

Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be used for flooring materials; doors such as footwear doors, closet doors, and kitchen doors; fitting materials such as frames, frames, baseboards; It can be suitably used for manufacturing interior building materials such as top boards such as boards.

The moisture-curable polyurethane hot-melt resin composition of the present invention is a reaction product of a specific polyol (a) and polyisocyanate (b) and contains a urethane prepolymer having isocyanate groups.

As the polyol (a), a polycarbonate polyol (a1) made from a glycol compound (x) having a branched structure is used to obtain excellent initial adhesive strength, final adhesive strength, and hydrolysis resistance. is required. The polycarbonate polyol (a1) has excellent hydrolysis resistance due to its carbonate structure, and the glycol compound (x), which is liquid but has high cohesion, reacts with the polyisocyanate (b), thereby exhibiting excellent hydrolysis resistance. Adhesion to substrates and initial adhesive strength can be obtained, and wettability is also good, so that excellent final adhesive strength can be obtained even after curing.

Specifically, the polycarbonate polyol (a1) can be a reaction product of a glycol compound containing a glycol compound (x) having a branched structure and a carbonate ester.

Examples of the glycol compound (x) having a branched structure include 2-methyl-1,3-propanediol, 2-methyl-1,3-pentanediol, 2-methyl-1,5-pentanediol, 3- Methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol , 2-butyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, neopentyl glycol, 2 -isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, 2-methyl-1,8-octane A diol or the like can be used. These compounds may be used alone or in combination of two or more.

As the glycol compound (x), among the above-described ones, it is easy to give a liquid polycarbonate polyol having even better adhesion to a substrate, and from the point that even better initial adhesive strength and hydrolysis resistance can be obtained, carbon It is preferable to use one having 4 to 6 atoms, and 2-methyl-1,3-propanediol and/or 2-methyl-1,3-pentanediol are more preferable.

As the glycol compound (x), when 2-methyl-1,3-propanediol (2M3PD) and 2-methyl-1,3-pentanediol (2M5PD) are used in combination, the molar ratio [2M3PD/ 2M5PD] is preferably in the range of 98/2 to 99.9/0.1, more preferably in the range of 99/1 to 99.8/0.2.

As a raw material for the polycarbonate polyol (a1), other glycol compounds than the glycol compound (x) can be used.

Examples of the other glycol compounds include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1, 8-octanediol, 1,9-nonanediol, 1,10-decanediol and the like can be used. In addition, γ-butyrolactone, hydroxybutanoic acid and esters thereof can also be used in combination. These compounds may be used alone or in combination of two or more.

The amount of the glycol compound (x) used is preferably 99 mol % or more of the total amount of the raw materials other than the carbonate ester from the viewpoint of obtaining even more excellent substrate adhesion and cohesive strength, and 99.5 mol% or more is more preferable.

Examples of the carbonate include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and methylethyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and 5-methyl-1,3-dioxan-2-one; Diaryl carbonate such as diphenyl can be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use one or more compounds selected from the group consisting of dimethyl carbonate, diethyl carbonate, and ethylene carbonate from the viewpoints of easy availability of raw materials and easy reaction control.

A known condensation reaction can be used for the reaction between the glycol compound (x) and the carbonate. It can be carried out under normal pressure or reduced pressure at a temperature of ~250°C.

The number average molecular weight of the polycarbonate polyol (a1) is preferably in the range of 100 to 5,000 from the viewpoint of obtaining even better initial adhesive strength, final adhesive strength, and hydrolysis resistance. A range of 200 to 4,000 is more preferred, and a range of 300 to 3,000 is even more preferred. The number average molecular weight of the polycarbonate polyol (a1) is the value measured by gel permeation chromatography (GPC).

The polyol (a) may contain other polyols in addition to the polycarbonate polyol (a1). Examples of other polyols that can be used include polycarbonate polyols other than the polycarbonate polyol (a1), polyester polyols, polyether polyols, polyacrylic polyols, polybutadiene polyols, hydrogenated polybutadiene polyols, dimer diols, and the like. These polyols may be used alone or in combination of two or more. These polyols may be used alone or in combination of two or more.

The amount of the polycarbonate polyol (a1) used in the polyol (a) is 5% by mass or more from the viewpoint of obtaining even more excellent initial adhesive strength, final adhesive strength, and hydrolysis resistance. is preferred, 20% by mass or more is more preferred, and 50% by mass or more is even more preferred.

Examples of the polyisocyanate (b) include aromatic polyisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, Aliphatic or alicyclic polyisocyanates such as dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, from the viewpoint of reactivity and adhesive strength, it is preferable to use aromatic polyisocyanate, and diphenylmethane diisocyanate is more preferable.

The urethane prepolymer is obtained by reacting the polyol (a) and the polyisocyanate (b). It has an isocyanate group capable of forming a crosslinked structure.

As a method for producing the urethane prepolymer, for example, the mixture of the polyol (a) is added dropwise to a reaction vessel containing the polyisocyanate (b), followed by heating to convert the isocyanate groups of the polyisocyanate (b) into , can be produced by reacting under conditions that are excessive with respect to the hydroxyl groups of the polyol (a).

In the production of the urethane prepolymer, the molar ratio (NCO/OH) of the hydroxyl groups of the polyol (a) and the isocyanate groups of the polyisocyanate (b) can impart a high cohesive force. It is preferably in the range of 5-5, more preferably in the range of 1.8-3.

The isocyanate group content (hereinafter abbreviated as "NCO %") of the urethane prepolymer obtained by the above method should be in the range of 1 to 10% by mass from the viewpoint of further improving the adhesive strength. is preferred, and a range of 2 to 5% by mass is more preferred. The NCO% of the urethane prepolymer is a value measured by potentiometric titration in accordance with JISK1603-1:2007.

Although the moisture-curable polyurethane hot-melt resin composition of the present invention contains the urethane prepolymer, it may contain other additives as necessary.

Examples of other additives include curing catalysts, antioxidants, tackifiers, plasticizers, light stabilizers, fillers, dyes, pigments, antifoaming agents, fluorescent brighteners, silane coupling agents, and waxes. , a thermoplastic resin, or the like can be used. These additives may be used alone or in combination of two or more.

As a method for obtaining a cured film of the moisture-curable polyurethane hot-melt resin composition, for example, the moisture-curable polyurethane hot-melt resin composition is melted at 50 to 130° C., coated on a substrate, and moisture-cured. method.

Examples of the base material include acrylic resins, urethane resins, silicone resins, epoxy resins, fluorine resins, polystyrene resins, polyester resins, polysulfone resins, polyarylate resins, polyvinyl chloride resins, Polyvinylidene chloride, cycloolefin resin, polyolefin resin, polyimide resin, alicyclic polyimide resin, cellulose resin, PC (polycarbonate), PBT (polybutylene terephthalate), modified PPE (polyphenylene ether), PEN (polyethylene) Naphthalate), PET (polyethylene terephthalate), lactic acid polymer, ABS resin, AS resin and other resin films; MDF, plywood, particle board and other wood substrates; non-woven fabric, woven fabric, knitted fabric and other fiber substrates; glass; rubber A base material or the like can be used. The base material may be subjected to corona treatment, plasma treatment, primer treatment, or the like, if necessary.

Examples of the method for applying the moisture-curable polyurethane hot-melt resin composition include methods using a roll coater, a spray coater, a T-die coater, a knife coater, a comma coater, and the like.

After the coating, the final adhesive strength can be obtained by aging for 0.5 to 3 days at a temperature of 20 to 80° C. and a relative humidity of 50 to 90%.

As described above, the moisture-curable polyurethane hot-melt resin composition of the present invention is excellent in initial adhesive strength, final adhesive strength, and hydrolysis resistance.

Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be used for flooring materials; doors such as footwear doors, closet doors, and kitchen doors; fitting materials such as frames, frames, baseboards; It can be suitably used for manufacturing interior building materials such as top boards such as boards.

The present invention will be described in more detail below using examples.

[Synthesis Example 1] Synthesis of Polycarbonate Polyol (a1-1) Into a reaction vessel equipped with a rectifying column, a stirrer, a thermometer and a nitrogen inlet tube, 425.5 parts by mass of 2-methyl-1,3-propanediol, 2.84 parts by mass of 2-methyl-1,3-pentanediol, 0.86 parts by mass of 1,4-butanediol, 448.8 parts by mass of dimethyl carbonate, and 0.003 parts by mass of lithium hydroxide were added and mixed, The mixture was reacted at 120 to 200° C. for 12 hours under normal pressure while distilling off low boiling point components. Furthermore, under reduced pressure, the reaction was continued at 150 to 170° C. for 8 hours while distilling off the component containing 2-methyl-1,3-propanediol to give a viscous liquid polycarbonate polyol (a1-1) (number average molecular weight 2,000).

[Synthesis Example 2] Synthesis of Polycarbonate Polyol (a1-2) Into a reaction vessel equipped with a rectifying column, a stirrer, a thermometer and a nitrogen inlet tube, 425.5 parts by mass of 2-methyl-1,3-propanediol, 2.8 parts by mass of 2-methyl-1,3-pentanediol, 0.41 parts by mass of γ-butyrolactone, 448.8 parts by mass of dimethyl carbonate, and 0.003 parts by mass of lithium hydroxide were added and mixed. The mixture was reacted at 120 to 200° C. for 12 hours while distilling off low boiling point components. Furthermore, under reduced pressure, the reaction was continued at 150 to 170° C. for 8 hours while distilling off the components containing 2-methyl-1,3-propanediol to give a viscous liquid polycarbonate polyol (a1-2) (number average molecular weight 2,000).

[Synthesis Example 3] Synthesis of Polycarbonate Polyol (a1-3) Into a reaction vessel equipped with a rectifying column, a stirrer, a thermometer and a nitrogen inlet tube, 425.5 parts by mass of 2-methyl-1,3-propanediol, 4.51 parts by mass of 2-methyl-1,3-pentanediol, 0.86 parts by mass of 1,4-butanediol, 0.41 parts by mass of γ-butyrolactone, 448.8 parts by mass of dimethyl carbonate, and 0.8 parts by mass of lithium hydroxide. 003 parts by mass were added and mixed, and reacted at 120 to 200° C. for 12 hours under normal pressure while distilling off low boiling point components. Furthermore, under reduced pressure, the reaction was continued at 150 to 170° C. for 8 hours while distilling off the component containing 2-methyl-1,3-propanediol to give a viscous liquid polycarbonate polyol (a1-3) (number average molecular weight 2,000).

[Example 1]
A four-necked flask equipped with a stirrer, a thermometer, an inert gas inlet and a reflux condenser was charged with 79.6 parts by mass of polycarbonate polyol (a1-1), and the water content was 0.05% by mass under reduced pressure. Dehydrated until:
Then, after cooling the temperature in the container to 70 ° C., 20.4 mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") was added, the temperature was raised to 100 ° C., and the isocyanate group content was The mixture was allowed to react for about 3 hours until it became constant to obtain a moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer having an isocyanate group.

[Examples 2-6, Comparative Examples 1-2]
A moisture-curable polyurethane hot-melt resin composition was obtained in the same manner as in Example 1, except that the types and amounts of polycarbonate polyol and polyisocyanate used were changed as shown in Tables 1 and 2.

[Method for measuring number average molecular weight]
The number average molecular weights of the polyols used in Examples and Comparative Examples are values measured under the following conditions by a gel permeation chromatography (GPC) method.

Measuring device: high-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm I.D. x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.

(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

[Method for evaluating initial adhesive strength]
The moisture-curable polyurethane hot-melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour, and then applied to a primer-treated olefin decorative sheet to a thickness of 50 μm. Then, a polyethylene terephthalate (PET) plate having a thickness of 3 mm was placed thereon and bonded together. After 10 minutes from the bonding, the sheet of the test piece was peeled off in the direction of 180°, and the peel strength (unit: N/25 mm) was measured.

[Evaluation method for final adhesive strength]
The moisture-curable polyurethane hot-melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour, and then applied to a primer-treated olefin decorative sheet to a thickness of 50 μm. Then, a polyethylene terephthalate (PET) plate having a thickness of 3 mm was placed thereon and bonded together. After curing for 5 days under conditions of 23° C. and 50% humidity, the sheet of the test piece was peeled off in the direction of 180° to measure the peel strength (unit: N/25 mm).

[Method for evaluating hydrolysis resistance]
The moisture-curable polyurethane hot-melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour, and then applied to a release-treated PET sheet to a thickness of 100 μm. This was aged for 5 days under conditions of 23° C. and 50% humidity. This cured film was allowed to stand in an atmosphere of 85° C. and 85% humidity for 3 weeks, and the retention rate of breaking tensile strength of the film before and after the standing was calculated and evaluated as follows.
“○”: 70% or more “×”: Less than 70%

Abbreviations in Table 2 are as follows.
“Solid PC”: Solid polycarbonate polyol (number average molecular weight: 2,000) made from 1,6-hexanediol
“Liquid PC”: liquid polycarbonate polyol (number average molecular weight: 2,000) made from 1,5-pentanediol and 1,6-hexanediol

It was found that the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent initial adhesive strength, final adhesive strength, and hydrolysis resistance.

On the other hand, in Comparative Example 1, a solid polycarbonate polyol made from 1,6-hexanediol was used instead of the polycarbonate polyol (a1), but the final adhesive strength was poor.

Comparative Example 2 is an embodiment using a liquid polycarbonate polyol made from 1,5-pentanediol and 1,6-hexanediol instead of the polycarbonate polyol (a1), but the initial adhesive strength was poor. rice field.

Claims (3)

A moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol (a) and a polyisocyanate (b),
The polyol (a) contains a polycarbonate polyol (a1) made from a glycol compound (x) having a branched structure,
The glycol compound (x) is a combination of 2-methyl-1,3-propanediol (2M3PD) and 2-methyl-1,3-pentanediol (2M5PD), and the molar ratio [2M3PD/2M5PD ] is in the range of 98/2 to 99.9/0.1 . An adhesive comprising the moisture-curable polyurethane hot-melt resin composition according to claim 1 . An article having a part bonded by the adhesive according to claim 2 .