JP7288174B2 - Moisture-curable polyurethane hot-melt resin composition and decorative board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a moisture-curable polyurethane hot-melt resin composition and a decorative board.

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. As the decorative board used for the floor material, for example, a decorative sheet is attached to each base material, and further processed such as tongue processing is performed, and the sheets are connected one by one without gaps. ) is widely used.

However, it has been pointed out that in this method, since the decorative sheet is attached to each base material, there is a lot of loss of the decorative sheet, and the application time is long, so that the productivity is low. In place of this, in recent years, a method of producing a large-area flooring material by forming grooves in a large-area base material and integrally laminating a decorative sheet thereon by vacuum lamination or the like has begun to be studied (for example, See Patent Document 1.).

Examples of the adhesive that can be used for the processing include a urethane prepolymer having an isocyanate group obtained by reacting a polyol containing an alicyclic polyester polyol and an aliphatic polyester polyol with 4,4'-diphenylmethane diisocyanate. A moisture-curable polyurethane hot-melt adhesive is known (see, for example, Patent Document 2).

However, the moisture-curable polyurethane hot-melt adhesive has a problem that adhesion of the decorative sheet is insufficient in the grooves of the base material, causing the decorative sheet to lift or peel off.

JP 2004-74657 A JP 2013-87150 A

The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt resin composition capable of imparting good initial adhesion between the grooves of the substrate and the sheet.

The present invention provides a moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, which is a reaction product of a polyol (a) and a polyisocyanate (b), wherein the polyol (a) contains a crystalline polyester polyol (a1-1) having a melting point of more than 80 ° C. and 140 ° C. or less, and the amount of the crystalline polyester polyol (a1-1) used is the same as the polyol (a) and the polyisocyanate (b ) in a range of 5 to 45 parts by mass in 100 parts by mass in total of ).

The present invention also provides a decorative board in which a base material and a decorative sheet are bonded together with an adhesive containing the moisture-curable hot-melt resin composition.

The moisture-curable polyurethane hot-melt resin composition of the present invention can provide good initial adhesion (hereinafter abbreviated as "initial adhesion") between the grooves of the substrate and the sheet.

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 an isocyanate group, which is a reaction product of a polyol (a) and a polyisocyanate (b). It is essential to use a specific amount of polyester polyol (a1-1).

It is essential that the crystalline polyester polyol (a1-1) has a melting point of more than 80° C. and 140° C. or less in order to impart excellent adhesiveness. By using a crystalline polyester polyol having such a melting point range, high cohesive force can be imparted when the sheet is heated and conformed to the grooves, so it is presumed that excellent initial adhesiveness can be obtained. The melting point of the crystalline polyester polyol (a1-1) is preferably in the range of 85 to 130° C., more preferably in the range of 90 to 120° C., from the viewpoint of obtaining even better initial adhesiveness. A range of 95 to 110° C. is more preferred.

Moreover, the amount of the crystalline polyester polyol (a1-1) used must be in the range of 5 to 45 parts by mass per 100 parts by mass of the total of the polyol (a) and the polyisocyanate (b). If the amount of (a1-1) used is less than 5 parts by mass, the resulting moisture-curable polyurethane hot-melt resin composition penetrates the substrate too much, making it impossible to obtain the desired initial adhesiveness. If the amount exceeds 45 parts by mass, it becomes difficult to melt the moisture-curable polyurethane hot-melt resin composition, making it difficult to apply the composition to a sheet, and the adhesiveness to the substrate is remarkably lowered, which is undesirable. initial adhesion cannot be obtained. The amount of the crystalline polyester polyol (a1-1) used is preferably in the range of 8 to 43 parts by mass, more preferably in the range of 10 to 42 parts by mass, from the viewpoint of obtaining even better initial adhesion and workability. is more preferable, the range of 15 to 41 parts by mass is more preferable, and the range of 30 to 40 parts by mass is particularly preferable.

As the crystalline polyester polyol (a1-1), specifically, for example, a reaction product of a compound having two or more hydroxyl groups and a polybasic acid can be used.

Examples of the compound having a hydroxyl group include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, and neopentyl glycol. , trimethylolpropane and the like 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 butanediol, hexanediol, octanediol and decanediol from the viewpoint of increasing crystallinity and further improving initial adhesiveness.

Examples of the polybasic acid include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, and phthalic anhydride. . These polybasic acids may be used alone or in combination of two or more. Among these, 1 selected from the group consisting of adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, and phthalic anhydride from the viewpoint of increasing crystallinity and further improving initial adhesiveness. It is preferred to use more than one kind of polybasic acid.

The melting point of the crystalline polyester polyol (a1-1) correlates with its crystallinity, and it is preferable to use a highly crystalline polyester polyol. The melting point and crystallinity of the polyester polyol can be adjusted by selecting raw material monomers, copolymerization composition, average molecular weight, and the like. In the present invention, the term “crystalline” means that a peak of heat of crystallization or heat of fusion can be confirmed in a DSC (differential scanning calorimeter) measurement conforming to JISK7121:2012, and the term “amorphous” is used. indicates that the peak cannot be confirmed. A method for measuring the melting point of the crystalline polyester polyol (a1-1) will be described in Examples.

A preferred composition of the crystalline polyester polyol (a1-1) is a reaction of hexanediol, sebacic acid, and phthalic acid (one or more selected from the group consisting of isophthalic acid, terephthalic acid, and orthophthalic acid). things are mentioned.

The number-average molecular weight of the crystalline polyester polyol (a1-1) is in the range of 500 to 5,000 from the viewpoint that the melting point can be easily adjusted and further excellent initial adhesion and workability can be obtained. is preferred, the range of 1,000 to 4,500 is more preferred, and the range of 2,000 to 4,000 is even more preferred. The number average molecular weight of the crystalline polyester polyol (a1-1) is the value measured by gel permeation chromatography (GPC).

The polyol (a) preferably further contains a crystalline polyester polyol (a1-2) having a melting point of 40 to 80°C. By using the above (a1-2), it is possible to achieve both permeability to the substrate and crystallinity, and to obtain even more excellent initial adhesiveness.

For the crystalline polyester polyol (a1-2), the same raw materials as those for (a1-1) can be used. Preferably, the compound having two or more hydroxyl groups is ethylene glycol, butanediol, and hexane. It is preferable to use one or more compounds selected from the group consisting of diols, and as the polybasic acid, one or more polybasic acids selected from the group consisting of adipic acid, sebacic acid, and dodecanedicarboxylic acid are used. is preferred.

The method for measuring the melting point of the crystalline polyester polyol (a1-2) is the same as that for the crystalline polyester polyol (a1-1).

The number average molecular weight of the crystalline polyester polyol (a1-2) is preferably in the range of 500 to 5,000, more preferably 1,500 to 4,500, from the viewpoint of obtaining even better initial adhesiveness. is more preferred, and a range of 2,000 to 4,000 is even more preferred. The number average molecular weight of the crystalline polyester polyol (a1-2) is the value measured by gel permeation chromatography (GPC).

As the crystalline polyester polyol (a1-2), polycaprolactone polyol can be used in addition to the above-mentioned polycaprolactone polyols. As the polycaprolactone polyol, a reaction product of the compound having two or more hydroxyl groups and ε-caprolactone can be used.

When polycaprolactone polyol is used as (a1-2), the number average molecular weight is preferably in the range of 5,000 to 200,000 from the viewpoint of further improving the open time and initial adhesiveness. A range of 10,000 to 150,000 is more preferred, and a range of 30,000 to 100,000 is even more preferred. The number average molecular weight of the polycaprolactone polyol is the value measured by gel permeation chromatography (GPC).

The total amount of the crystalline polyester polyols (a1-1) and (a1-2) used is 100 parts by mass in total of the polyol (a) and the polyisocyanate (b) from the viewpoint of obtaining even better adhesion. It is preferably at least 50 parts by mass, more preferably in the range of 50 to 80 parts by mass.

The polyol (a) may be used in combination with other polyols in addition to the above (a1-1) and (a1-2).

Examples of other polyols that can be used include polyester polyols other than (a1-1) and (a1-2), polyether polyols, polyacrylic polyols, and polycarbonate polyols. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use polyester polyols other than the above (a1-1) and (a1-2), since they provide better adhesion. The number average molecular weight of polyester polyols other than (a1-1) and (a1-2) is preferably in the range of 500 to 10,000. The number average molecular weight of the polyester polyol is a value measured by gel permeation chromatography (GPC).

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, aromatic polyisocyanate is preferably used, and diphenylmethane diisocyanate is more preferably used, from the viewpoint of reactivity and adhesiveness.

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, and more preferably in the range of 1.8 to 3, from the viewpoint that a high cohesive force 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. A range is preferred, a range of 2 to 5% by mass is more preferred, and a range of 2.5 to 4% by weight is even 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.

Next, the decorative board of the present invention will be described.

The decorative board is obtained by bonding a base material and a decorative sheet via an adhesive, and the adhesive contains the moisture-curable polyurethane hot-melt resin composition.

Examples of the substrate include wooden substrates such as plate-like wood, laminated lumber, plywood, MDF (medium density fiberboard), and particle boards; and inorganic substrates such as hard cement calcium silicate boards. can.

The thickness, width, and length of the base material are appropriately determined according to the use of the decorative board. A thickness range of 2 to 18 mm may be mentioned.

In the present invention, the base material has grooves in the longitudinal direction (the direction in which the width is longer. When the widths are the same in length and width, either one is indicated.) and in at least one direction other than the longitudinal direction. Good adhesiveness to the grooves of the decorative sheet can be imparted even when the material having the adhesive is used. The number of longitudinal grooves may be one or two or more, and the number of non-longitudinal grooves may be one or two or more. The direction of the grooves other than the longitudinal direction is preferably perpendicular to the longitudinal direction from the viewpoint of the highest frequency of use and the ease with which the decorative sheet follows the grooves in terms of line production.

Examples of the grooves of the substrate include cylindrical grooves, triangular grooves, planar grooves, dovetail grooves, and the like. These grooves may be of one type or a mixture of two or more types. Among these, triangular grooves are preferable because they are frequently used in flooring materials and the like, and have good conformability to the grooves of the decorative sheet.

The depth of the groove is appropriately determined according to the use of the decorative board, and is, for example, in the range of 0.5 to 3 mm. Also, the width of the groove is, for example, in the range of 0.5 to 3 mm.

The decorative sheet that can be used in the present invention may be plain or decorated with a decorative color or pattern. Examples of materials for the decorative sheet include resins such as polyvinyl chloride, polyolefin, polymethyl methacrylate, polyester, polyamide, polystyrene, polycarbonate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene, and polypropylene; Examples include paper, non-woven fabric, woven fabric, thin wooden veneer, tatami facing, and the like. Among these, it is preferable to use polyvinyl chloride, polyolefin, polymethyl methacrylate, and polyester from the point of followability to the groove.

The thickness of the decorative sheet is preferably in the range of 0.05 to 0.3 mm, more preferably in the range of 0.1 to 0.2 mm, from the viewpoint of excellent followability to the grooves.

The moisture-curable polyurethane hot-melt resin composition is used for bonding the base material and the decorative sheet. 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.

The decorative sheet of the present invention is obtained by bonding the base material and the decorative sheet together, and the decorative sheet is continuously bonded to the side surface portion, the flat surface portion, and the groove portions provided on the flat surface portion of the base material. A decorative sheet may also be adhered to the rear surface portion (back side of the flat surface portion).

Next, a method for manufacturing the decorative board of the present invention will be described.

The decorative plate of the present invention can be produced, for example, by applying an adhesive onto the decorative sheet, bonding the decorative sheet to the substrate flat surface having the grooves, the side surface, and optionally the back surface, and (i) then A method of locally heating the decorative sheet corresponding to the grooves of the base material to locally soften the decorative sheet and press it against the grooves of the base material; be done. The vacuum lamination may be performed while applying heat.

As described above, the moisture-curable polyurethane hot-melt resin composition of the present invention can provide good adhesion between the grooves of the substrate and the sheet.

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]
A crystalline polyester polyol (hexanediol, terephthalic acid, and sebacic acid reacted, melting point: 100°C, number average Molecular weight: 2,000, hereinafter abbreviated as “crystalline PEs-1”) 25 parts by mass, crystalline polyester polyol (a reaction product of hexanediol and dodecanedicarboxylic acid, melting point: 72° C., number average molecular weight: 3 , 500, hereinafter abbreviated as “crystalline PEs-2”) 40 parts by mass, crystalline polyester polyol (polycaprolactone polyol, melting point: 50° C., number average molecular weight: 80,000, hereinafter “crystalline PEs-3” ) 10 parts by mass, other polyester polyol (ethylene glycol, neopentyl glycol, hexanediol, and adipic acid reacted, number average molecular weight: 5,000, hereinafter abbreviated as “other PEs-1” ) and 2 parts by mass of polyoxyethylene polyoxypropylene glycol (number average molecular weight: 4,000, hereinafter abbreviated as “PEt-1”) are charged, and heated under reduced pressure at 90 ° C. to contain moisture. Dehydration was carried out until the ratio became 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 18 parts by mass of 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”) was added, and the temperature was raised to 110° C. to reduce the isocyanate group content. The mixture was allowed to react for about 3 hours until it became constant to obtain a urethane prepolymer having an isocyanate group. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.14, and the NCO% of the urethane prepolymer was 2.50% by mass.

[Example 2]
25 parts by mass of crystalline PEs-1, 25 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-neck flask equipped with a stirrer, a thermometer, an inert gas inlet and a reflux condenser. parts by mass, crystalline polyester polyol (a reaction product of hexanediol and adipic acid, melting point: 58°C, number average molecular weight: 4,500, hereinafter abbreviated as "crystalline PEs-4") 15 parts by mass, others 5 parts by mass of PEs-1 and 2 parts by mass of PEt-1 were added and dehydrated by heating under reduced pressure at 90° C. until the water content was 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 18 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.22, and the NCO% of the urethane prepolymer was 2.58% by mass.

[Example 3]
30 parts by mass of crystalline PEs-1, 30 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-necked flask equipped with a stirrer, a thermometer, an inert gas inlet and a reflux condenser. Parts by mass, 10 parts by mass of PEs-1, and 2 parts by mass of PEt-1 were charged, and dehydrated by heating under reduced pressure at 90° C. until the water content was 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 18 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.77, and the NCO% of the urethane prepolymer was 3.86% by mass.

[Example 4]
40 parts by mass of crystalline PEs-1, 20 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-necked flask equipped with a stirrer, thermometer, inert gas inlet and reflux condenser. Parts by mass, 10 parts by mass of PEs-1, and 2 parts by mass of PEt-1 were charged, and dehydrated by heating under reduced pressure at 90° C. until the water content was 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 18 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.19, and the NCO% of the urethane prepolymer was 2.93% by mass.

[Example 5]
42 parts by mass of crystalline PEs-1, 10 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-necked flask equipped with a stirrer, thermometer, inert gas inlet and reflux condenser. Parts by mass, 10 parts by mass of crystalline PEs-4, 10 parts by mass of other PEs-1, and 2 parts by mass of PEt-1 are charged, and heated under reduced pressure at 90 ° C. to make the water content 0.05 mass% or less. dehydrated until
Next, after cooling the temperature in the reaction vessel to 60° C., 16 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.24, and the NCO% of the urethane prepolymer was 2.98% by mass.

[Example 6]
A crystalline polyester polyol (hexanediol, terephthalic acid, and adipic acid reacted, melting point: 96°C, number average Molecular weight: 3,500, hereinafter abbreviated as “crystalline PEs-5”) is 42 parts by mass, crystalline PEs-2 is 23 parts by mass, crystalline PEs-3 is 10 parts by mass, and other PEs-1 is 10 parts by mass. Parts by mass and 2 parts by mass of PEt-1 were charged, and dehydration was performed by heating under reduced pressure at 90° C. until the moisture content became 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 13 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.47, and the NCO% of the urethane prepolymer was 2.6% by mass.

[Comparative Example 1]
60 parts by mass of crystalline PEs-1, 10 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-necked flask equipped with a stirrer, thermometer, inert gas inlet and reflux condenser. It was dehydrated until the water content was 0.05% by mass or less by charging in parts by mass and heating at 90° C. under reduced pressure.
Next, after cooling the temperature in the reaction vessel to 60° C., 20 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.43, and the NCO% of the urethane prepolymer was 3.95% by mass.

[Comparative Example 2]
50 parts by mass of crystalline PEs-1, 10 parts by mass of crystalline PEs-2, and 10 parts by mass of crystalline PEs-3 were added to a four-necked flask equipped with a stirrer, a thermometer, an inert gas inlet and a reflux condenser. It was dehydrated until the water content was 0.05% by mass or less by charging in parts by mass and heating at 90° C. under reduced pressure.
Next, after cooling the temperature in the reaction vessel to 60° C., 17 parts by mass of MDI is added, the temperature is raised to 110° C., and the reaction is continued for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.15, and the NCO% of the urethane prepolymer was 3.05% by mass.

[Comparative Example 3]
30 parts by mass of crystalline PEs-2, 10 parts by mass of crystalline PEs-3 and 30 parts by mass of crystalline PEs-4 were added to a four-necked flask equipped with a stirrer, thermometer, inert gas inlet and reflux condenser. Parts by mass, 10 parts by mass of PEs-1, and 2 parts by mass of PEt-1 were charged, and dehydrated by heating under reduced pressure at 90° C. until the water content was 0.05% by mass or less.
Next, after cooling the temperature in the reaction vessel to 60° C., 18 parts of MDI is added, the temperature is raised to 110° C., and the reaction is allowed to proceed for about 3 hours until the isocyanate group content becomes constant, resulting in a urethane having an isocyanate group. A prepolymer was obtained. The NCO/OH ratio at the time of production of the obtained urethane prepolymer was 2.77, and the NCO% of the urethane prepolymer was 3.86% by mass.

[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

[Measuring method of melting point of crystalline polyester polyol]
10 mg of each crystalline polyester polyol was weighed into a measurement container, and a differential scanning calorimeter ("DSC 220C" manufactured by Seiko Electronics Co., Ltd.) was used to measure 20% at a nitrogen gas flow rate of 50 ml/min and a heating rate of 10°C/min. C. to 210.degree. C., then held at 210.degree. C. for 3 minutes, cooled to -100.degree. C. at a cooling rate of 50.degree. The melting point (°C) was determined from the DSC curve obtained.

[Method for making decorative board]
Moisture-curing obtained in Examples and Comparative Examples using a T-die coater on the back of a vinyl chloride decorative sheet with a wood grain pattern (thickness 130 μm, softening point 50° C., hereinafter abbreviated as “PVC”). A polyurethane hot-melt resin composition was applied to a thickness of 60 μm, and the adhesive layer was applied to a base material (MDF of 182 cm long, 31 cm wide, and 9 mm thick, with triangular grooves forming a rectangle of 60 cm long and 15 cm wide). (Grooves with a width of 1 mm and a depth of 0.8 mm) were laminated while being pressed while being continuously formed so as to be sequentially shifted by half in the longitudinal direction. Then, the surplus portion of the decorative sheet was folded on the four side surfaces of the base material and crimped.
Subsequently, the decorative sheet corresponding to the groove portion of the substrate was pressed against a pressing jig heated to 80° C. and locally heated to be softened and elongated to be pressed against the bottom surface of the groove of the substrate. After that, a decorative board was obtained by pressing an unheated pressing jig to cool and crimp.

[Method for evaluating adhesiveness]
Adhesion was evaluated by the following two methods.

<Final Adhesion>
After curing the decorative plate prepared by the above method at 23° C. for 5 days, the cross section of the groove was observed to evaluate the final adhesion.
"◯": No lifting of the decorative sheet was observed.
"Fair": Lifting of the decorative sheet was partially confirmed, but it was at a practically acceptable level.
"X": Adhesion was not possible.

<Creep test>
The moisture-curable polyurethane hot-melt compositions obtained in Examples and Comparative Examples were each melted at a temperature of 120° C. for 1 hour. The adhesive was applied onto a polyethylene terephthalate sheet using an applicator to a thickness of 50 μm. It was left at 23°C for 15 minutes and then at 80°C for 2 minutes. An MDF (medium density fiberboard) was laminated on the coating layer at 80° C. and pressed with a pressing roller. A load of 75 g was applied in a 90° direction to a test piece having a width of 25 mm after crimping, and the peel length (mm) of the polyethylene terephthalate sheet after 15 minutes was measured and evaluated as follows.
"◯": The peel length was 5 mm or less.
"Δ": The peeled length exceeded 5 mm and was 10 mm or less.
"X": The peel length exceeded 10 mm, or the weight fell.

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

On the other hand, Comparative Examples 1 and 2, in which the amount of the crystalline polyester polyol (a1-1) used exceeded the range specified in the present invention, had poor adhesiveness.

Comparative Example 3 is an embodiment in which the crystalline polyester polyol (a1-1) was not used, but the adhesion was poor.

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) is
containing a crystalline polyester polyol (a1-1) having a melting point of 95 to 110° C. ,
Furthermore, a crystalline polyester polyol obtained by reacting hexanediol and dodecanedicarboxylic acid, a polycaprolactone polyol, a polyester polyol obtained by reacting ethylene glycol, neopentyl glycol, hexanediol and adipic acid, and polyoxyethylene polyoxypropylene glycol and
The amount of the crystalline polyester polyol (a1-1) used is in the range of 5 to 45 parts by mass based on the total of 100 parts by mass of the polyol (a) and the polyisocyanate (b),
A moisture-curable polyurethane hot-melt resin composition, wherein the crystalline polyester polyol (a1-1) is a reaction product of hexanediol, sebacic acid and phthalic acid. The moisture-curable polyurethane hot-melt resin according to claim 1 , wherein the molar ratio [NCO/OH] of the hydroxyl groups of the polyol (a) and the isocyanate groups of the polyisocyanate (b) is in the range of 1.5 to 5. Composition. A decorative board in which a base material and a decorative sheet are bonded together with an adhesive, wherein the adhesive contains the moisture-curable polyurethane hot-melt resin composition according to claim 1 or 2 . veneer.