JP7176389B2 - Moisture-curable polyurethane hot-melt resin composition, adhesive, and article - Google Patents

Description

The present invention relates to a moisture-curable polyurethane hot-melt resin composition and an adhesive.

A decorative board in which a decorative sheet is bonded to a plate-like base material is widely used for building interior materials such as floor materials, doors, fixture members, and top boards. Urethane-based adhesives, epoxy-based adhesives, modified silicone resin-based adhesives, acrylic-based adhesives, and the like have been used for bonding the base material and the decorative sheet. Among these, in recent years, the use of moisture-curable polyurethane hot-melt adhesives, which exhibit excellent final adhesive strength due to moisture-curing, is increasing.

Moisture-curable polyurethane hot-melt adhesives used for the decorative board include, for example, an isocyanate-terminated urethane prepolymer and specific amounts of an epoxy group-containing silane coupling agent and a (meth)acryloyl group-containing silane coupling agent. Moisture-curable polyurethane hot-melt adhesives are disclosed (see, for example, Patent Document 1).

However, it has been pointed out that the adhesive has insufficient hydrolysis resistance and that the decorative sheet peels off over time.

JP 2011-225635 A

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

The present invention contains a polyol (a) containing a crystalline polyester polyol (a-1) which is a reaction product of hexanediol and adipic acid, and a urethane prepolymer having an isocyanate group which is a reaction product of a polyisocyanate (b). A moisture-curable polyurethane hot-melt resin composition, wherein the proportion of the crystalline polyester polyol (a-1) used is 10 to 35% by mass in the total mass of the polyol (a) and the polyisocyanate (b). range, and the polyisocyanate (b) contains a diisocyanate (b-1) and a polymethylene polyphenyl polyisocyanate (b-2). It provides

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

The moisture-curable polyurethane hot-melt resin composition of the present invention has excellent adhesiveness and hydrolysis resistance.

Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used as an adhesive for laminating decorative boards. In addition, the obtained veneer can be used as a flooring material; doors such as shoe doors, closet doors, and kitchen doors; building materials such as frames, frames, and baseboards; It can be used suitably, and can be used particularly suitably as a flooring material.

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

The crystalline polyester polyol (a-1) is a reaction product of hexanediol and adipic acid, and is an essential component for imparting adhesive strength. The proportion of (a-1) used must be in the range of 10 to 35% by mass based on the total mass of the polyol (a) and the polyisocyanate (b). If the amount of (a-1) used is less than 10% by mass, the adhesiveness will be insufficient, and if it exceeds 35% by mass, the hydrolysis resistance will be poor. The proportion of the (a-1) used is 13 to 27 masses in the total mass of the polyol (a) and the polyisocyanate (b) from the viewpoint of obtaining even better adhesion and hydrolysis resistance. % range, more preferably 15 to 25% by mass.

In the present invention, the term “crystalline” means that a peak of heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimeter) measurement conforming to JISK7121:2012. indicates that the peak cannot be confirmed.

The number average molecular weight of the crystalline polyester polyol (a-1) is preferably in the range of 500 to 10,000, preferably 700 to 7,000, from the viewpoint of obtaining even better crystallinity and adhesiveness. A range of 000 is more preferred, and a range of 1,500 to 6,000 is even more preferred. The number average molecular weight of the crystalline polyester polyol (a-1) is the value measured by gel permeation chromatography (GPC).

The polyol (a) contains polyols other than (a-1). Examples of the other polyols include polyether polyol (a-2), polyacrylic polyol (a-3), crystalline polyester polyols other than (a-1) (a-4), and crystalline polyester polyols other than polyester polyol, polycarbonate polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, etc. can be used. These polyols may be used alone or in combination of two or more. Among these, the polyether polyol (a-2), the polyacryl polyol (a-3), and the above (a-1 ), it is preferable to use a crystalline polyester polyol (a-4) other than (a-4).

Examples of the polyether polyol (a-2) include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, and polyoxypropylene. Polyoxytetramethylene glycol, polyoxypropylene triol and the like can be used. These polyether polyols may be used alone or in combination of two or more.

Among these, it is preferable to use polyoxypropylene glycol and/or polyoxyethylene polyoxypropylene glycol from the viewpoint of obtaining even more excellent adhesiveness by increasing the permeability to the substrate. It is preferable to use oxypropylene glycol and polyoxyethylene polyoxypropylene glycol together.

When the polyoxypropylene glycol (PO) and polyoxyethylene polyoxypropylene glycol (EOPO) are used in combination, the mass ratio [PO/EOPO] is 30/70 from the viewpoint of obtaining even better adhesion. It is preferably in the range of ~90/10, more preferably in the range of 40/60 to 80/20, and even more preferably in the range of 55/45 to 70/30.

The number average molecular weight of the polyether polyol (a-2) is preferably in the range of 500 to 100,000, from the viewpoint of obtaining even better adhesion and hydrolysis resistance. A range of 000 is more preferred, and a range of 600 to 5,000 is even more preferred. The number average molecular weight of the polyether polyol (a-2) is the value measured by gel permeation chromatography (GPC).

When the polyether polyol (a-2) is used, the content of the polyether polyol (a-2) is the total of the polyol (a) and the polyisocyanate (b) from the viewpoint of obtaining a better balance between adhesion and hydrolysis resistance. It is preferably in the range of 10 to 45% by mass, more preferably in the range of 20 to 40% by mass.

As the polyacrylic polyol (a-3), for example, a polymer of a (meth)acrylic compound essentially containing a (meth)acrylic compound having a hydroxyl group can be used.

In the present invention, "(meth)acrylic compound" refers to a methacrylic compound and/or an acrylic compound, "(meth)acrylate" refers to methacrylate and/or acrylate, and "(meth)acrylic acid". indicates methacrylic acid and/or acrylic acid.

Examples of the (meth)acrylic compound having a hydroxyl group include, for example, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth) ) acrylates and the like can be used. These compounds may be used alone or in combination of two or more.

Other (meth)acrylic compounds include, for example, (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth) Acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cetyl (meth)acrylate, lauryl (meth)acrylate, etc. (Meth)acrylic acid alkyl ester (meth)acrylic acid alkyl ester; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H - Octafluoropentyl (meth) acrylate, 2-(perfluorooctyl) ethyl (meth) acrylate having a fluorine atom (meth) acrylic compounds; isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentanyl ( (meth)acrylic compounds having an alicyclic structure such as meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate; polyethylene glycol mono(meth)acrylate, methoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxytri (Meth)acrylic compounds having an ether group such as ethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate; benzyl (meth)acrylate, 2-ethyl-2-methyl-[1,3]-dioxolane-4- yl-methyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and the like can be used. These (meth)acrylic compounds may be used alone or in combination of two or more.

As the (meth)acrylic compound, among those described above, it is preferable to use the (meth)acrylic compound having a hydroxyl group and the (meth)acrylic acid alkyl ester from the viewpoint of further improving the open time and adhesive strength. , 2-hydroxyethyl (meth)acrylate, methyl (meth)acrylate and n-butyl (meth)acrylate.

The number average molecular weight of the polyacrylic polyol (a-3) is preferably in the range of 5,000 to 50,000, preferably 10,000 to 30, from the viewpoint of further improving the open time and adhesive strength. A range of 000 is more preferred. The number average molecular weight of the polyacrylic polyol (a-2) is the value measured by gel permeation chromatography (GPC).

The glass transition temperature of the polyacrylic polyol (a-3) is preferably in the range of 30 to 120°C, more preferably in the range of 50 to 80°C, from the viewpoint of further improving the open time and adhesive strength. . The glass transition temperature of the polyacrylic polyol (a-2) is a value measured by a DSC (differential scanning calorimeter) in accordance with JISK7121-1987. The polyacrylic polyol (a-2) was put in, heated to (glass transition temperature + 50 ° C.) at a temperature increase rate of 10 ° C./min, held for 3 minutes, then rapidly cooled, and from the obtained differential thermal curve The midpoint glass transition temperature (Tmg) reading is shown.

When the acrylic polyol (a-3) is used, the proportion used is 5 to 25% by mass in the total mass of the polyol (a) and the polyisocyanate (b), since the open time and adhesive strength can be further improved. is preferably in the range of , more preferably in the range of 10 to 20% by mass.

As the crystalline polyester polyol (a-4), it is possible to use those other than the above (a-1), for example, a reaction product of a compound having a hydroxyl group and a polybasic acid.

Examples of the compound having a hydroxyl group include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, and the like. can be done. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use one or more selected from the group consisting of butanediol, hexanediol, octanediol, and decanediol from the viewpoint of enhancing crystallinity and further improving adhesiveness and hydrolysis resistance.

Examples of polybasic acids that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecanedioic acid. These polybasic acids may be used alone or in combination of two or more. Among these, it is possible to use one or more selected from the group consisting of adipic acid, sebacic acid, and dodecanedioic acid from the viewpoint of increasing crystallinity and further improving adhesiveness and hydrolysis resistance. preferable.

As the crystalline polyester polyol (a-4), polycaprolactone polyol may be used in addition to the above.

As the polycaprolactone polyol, for example, a reaction product of the compound having a hydroxyl group and ε-caprolactone can be used.

The number average molecular weight of the crystalline polyester polyol (a-4) is preferably in the range of 500 to 10,000 from the viewpoint of further improving crystallinity, adhesive strength and hydrolysis resistance. A range of 000 to 8,000 is more preferred, and a range of 1,500 to 7,000 is even more preferred. Further, when the caprolactone polyol is used as the crystalline polyester polyol (a-4), the number average molecular weight thereof is 20,000 from the viewpoint of further improving crystallinity, adhesive strength and hydrolysis resistance. A range of ~200,000 is preferred, and a range of 30,000 to 100,000 is more preferred. The number average molecular weight of the crystalline polyester polyol (a-4) is the value measured by gel permeation chromatography (GPC).

When the crystalline polyester polyol (a-4) is used, the ratio of use is the total of the polyol (a) and the polyisocyanate (b) from the viewpoint of further improving the crystallinity, adhesive strength and hydrolysis resistance. It is preferably in the range of 5 to 25% by mass, more preferably in the range of 7 to 18% by mass.

As the polyisocyanate (b), it is essential to contain a diisocyanate (b-1) and a polymethylene polyphenyl polyisocyanate (b-2) from the viewpoint of obtaining excellent adhesiveness and hydrolysis resistance. be.

Examples of the diisocyanate (b-1) include diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate and other aromatic diisocyanates, hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, Diisocyanates such as aliphatic or alicyclic diisocyanates 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, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, from the viewpoint of obtaining even better reactivity and adhesiveness.

（式（２）中、ｎは１以上の整数である。） Specifically, the polymethylene polyphenyl polyisocyanate (b-2) is represented by the following formula (2), and preferably, in formula (2), n is an integer of 1 to 5. be.

(In formula (2), n is an integer of 1 or more.)

The proportion of the polymethylene polyphenyl polyisocyanate (b-2) used is the polyol (a) and the polyisocyanate from the viewpoint of obtaining even more excellent initial adhesion, final adhesion, and hydrolysis resistance. It is preferably in the range of 1 to 10% by mass, more preferably in the range of 1.5 to 8% by mass, and even more preferably in the range of 2 to 5% by mass, based on the total mass of (b).

The mass ratio [(b-1)/(b-2)] of the diisocyanate (b-1) and the polymethylene polyphenyl polyisocyanate (b-2) provides even better initial adhesion and final adhesion. From the viewpoint of obtaining good properties and hydrolysis resistance, it is preferably in the range of 20/1 to 2/1, more preferably in the range of 15/1 to 5/1.

As the polyisocyanate (b), in addition to the above (b-1) and (b-2), other polyisocyanates may be used in combination if necessary. As the other polyisocyanate, for example, the isocyanurate compound (b-1); adduct compound; burette compound; allophanate compound and the like can be used. These isocyanates may be used alone or in combination of two or more. The proportion of (b-1) and (b-2) used is preferably 50% by mass or more, more preferably 80% by mass or more, in the polyisocyanate (b).

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).

When producing the urethane prepolymer, the molar ratio (NCO / OH) of the hydroxyl group of the polyol (a) and the isocyanate group of the polyisocyanate (b) is reduced to reduce unreacted polyisocyanate, and It is preferably in the range of 1.5 to 5, more preferably in the range of 1.8 to 3, from the point that high cohesive strength can be imparted.

The isocyanate group content (hereinafter abbreviated as "NCO %") of the urethane prepolymer obtained by the above method is 1 to 10% by mass from the viewpoint of further improving the adhesiveness at high temperatures. It is preferably in the range, more preferably in the range of 2 to 5% by mass, and even more preferably in the range of 2.5 to 4.5% by mass. 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.

Next, articles will be described.

The article is obtained by bonding at least two articles together with an adhesive containing the moisture-curable polyurethane hot-melt resin composition.

Examples of the article to be bonded include wood substrates such as plate-shaped wood, laminated lumber, plywood, MDF (medium density fiberboard), and particle boards; inorganic substrates such as hard cement calcium silicate boards; Sheet; glass; rubber; plastic molding; decorative paper, non-woven fabric, woven fabric, projecting board;

The thickness of the adhesive layer can be determined appropriately as long as sufficient adhesiveness is obtained, and for example, the thickness is in the range of 0.03 to 0.15 mm.

As described above, the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent adhesiveness and hydrolysis resistance.

Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used as an adhesive for laminating decorative boards. In addition, the obtained veneer can be used as a flooring material; doors such as shoe doors, closet doors, and kitchen doors; building materials such as frames, frames, and baseboards; It can be used suitably, and can be used particularly suitably as a flooring material.

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

[Example 1]
12 parts by mass of polyoxypropylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as "PPG1000"), poly Oxypropylene glycol (number average molecular weight; 2,000, hereinafter abbreviated as "PPG2000") 10 parts by mass, polyoxyethylene polyoxypropylene glycol (number average molecular weight; 4,000, hereinafter abbreviated as "EOPO") 7 parts by mass, polyacrylic polyol (reaction product of methyl methacrylate, butyl methacrylate, and 2-hydroxyethyl methacrylate, number average molecular weight; 20,000, hereinafter abbreviated as "Acpoly") 15 parts by mass, crystalline polyester polyol ( Reaction product of 1,6-hexanediol and adipic acid, number average molecular weight; Dodecanedioic acid reactant, number average molecular weight: 3,500, hereinafter abbreviated as “crystalline PEs-2”). Dehydrated to less than %.
Then, after cooling the temperature in the reaction vessel to 60 ° C., 18 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI"), polymethylene polyphenyl polyisocyanate (manufactured by Tosoh Corporation "Millionate MR- 200", hereinafter abbreviated as "polymeric MDI".), heated to 110°C, and reacted for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane prepolymer having an isocyanate group. got The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.4, and the NCO% of the urethane prepolymer was 4.1% by mass.

[Examples 2 to 4, Comparative Examples 1 to 3]
A urethane prepolymer was obtained in the same manner as in Example 1, except that the amount of each polyol used was changed as shown in Table 1.

[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 adhesiveness]
The moisture-curable polyurethane hot-melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour and then coated onto a polyethylene terephthalate sheet to a thickness of 50 μm using an applicator. MDF was laminated thereon, pressed with a pressing roller, and left for 5 days under conditions of 23° C. and 50% humidity for aging. After that, in an atmosphere of 23° C. and 50% humidity, the average peel force was measured when peeled in 180 degrees direction at a speed of 200 mm/min with respect to a width of 25 mm, and evaluated as follows.
"○": 25N/25mm or more "X": less than 25N/25mm

[Method for evaluating hydrolyzability]
The moisture-curable polyurethane hot-melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour and then coated onto a polyethylene terephthalate sheet to a thickness of 50 μm using an applicator. MDF was laminated thereon, pressed with a pressing roller, and left for 5 days under conditions of 23° C. and 50% humidity for aging. After that, under an atmosphere of 85° C. and humidity of 85%, a load of 70 g was applied to a width of 25 mm in a direction of 90° C., and the number of days until the load dropped was measured and evaluated as follows.
“○”: 25 days or more “×”: Less than 25 days

It was found that the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent adhesion and hydrolysis resistance.

On the other hand, in Comparative Example 1, the amount of the crystalline polyester polyol (a-1) used was below the range specified in the present invention, but the adhesion was poor.

Comparative Example 2 was an embodiment in which the amount of the crystalline polyester polyol (a-2) used exceeded the range specified in the present invention, but the hydrolysis resistance was poor.

Comparative Example 3 is an embodiment in which polymethylene polyphenyl isocyanate (b-2) is not used, but the hydrolysis resistance is poor.

Claims (5)

A moisture-curable type containing a polyol (a) containing a crystalline polyester polyol (a-1) which is a reaction product of hexanediol and adipic acid and a urethane prepolymer having an isocyanate group which is a reaction product of polyisocyanate (b) A polyurethane hot melt resin composition,
The use ratio of the crystalline polyester polyol (a-1) is
in the range of 10 to 35% by mass of the total mass of the polyol (a) and polyisocyanate (b),
The polyol (a) further contains a polyether polyol (a-2), and the polyether polyol (a-2) is polyoxypropylene glycol (PO) and polyoxyethylene polyoxypropylene glycol (EOPO). and the mass ratio [PO / EOPO] in the range of 30/70 to 90/10,
A moisture-curable polyurethane hot-melt resin composition, wherein the polyisocyanate (b) contains a diisocyanate (b-1) and a polymethylene polyphenyl polyisocyanate (b-2). The humidity according to claim 1, wherein the polyol (a) further contains a polyacrylic polyol (a-3) and a crystalline polyester polyol (a-4) other than the (a-1). A curable polyurethane hot-melt resin composition. The moisture-curing according to claim 1 or 2, wherein the content of the polymethylene polyphenyl polyisocyanate (b-2) is in the range of 1 to 10% by mass of the total mass of the polyol (a) and the polyisocyanate (b). type polyurethane hot melt resin composition. An adhesive comprising the moisture-curable polyurethane hot-melt resin composition according to claim 1 or 2. An article comprising at least two articles bonded together by the adhesive according to claim 4.