JP6972532B2 - Moisture Curable Polyurethane Hot Melt Composition - Google Patents

Description

The present invention relates to a moisture-curable polyurethane hot melt composition having excellent initial strength and hydrolysis resistance.

For materials with curved or uneven surfaces used for building materials such as kitchen doors, closet doors, window frames, and furniture such as counter tables, olefin sheets with wood grain printing are applied to improve the design. Wrapping processing is widely performed in which synthetic resin decorative sheets such as PET (polyethylene terephthalate) sheets, resin-processed papers, and surface covering sheets such as attached plates are continuously wrapped and attached using an adhesive.

When lapping, a durable adhesive such as strong initial strength and hydrolysis resistance is required for a material having a curved surface or unevenness on the surface.

As the adhesive that can be used for the wrapping process, for example, 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 is used. Moisture curable polyurethane hot melt adhesives containing are known (see, for example, Patent Document 1).

Although the moisture-curable polyurethane hot-melt adhesive has excellent initial adhesiveness, improvement in hydrolysis resistance has been required.

Japanese Unexamined Patent Publication No. 2013-87150

An object to be solved by the present invention is to provide a moisture-curable polyurethane hot melt composition having excellent initial strength and hydrolysis resistance.

The present invention is an isocyanate which is a reaction product of a polyol (A) containing a polyester polyol (A-1) represented by the following formula (1) and a polyisocyanate (B) containing a polyfunctional isocyanate (B-1). The present invention relates to a moisture-curable polyurethane hot melt composition, which comprises a urethane prepolymer having a group.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立して炭素原子数が偶数である直鎖のアルキレン基を示し、Ｒ^１及びＲ^２の有する炭素原子数の合計は１２以上であり、ｎは３〜４０の整数を示す。）

(In the formula (1), R ¹ and R ² each independently represent a linear alkylene group having an even number of carbon atoms, and the total number of carbon atoms of ^{R 1} and R ^{2 is 12 or more.} , N represents an even number from 3 to 40.)

The moisture-curable urethane hot-melt composition of the present invention is excellent in initial strength and hydrolysis resistance. Therefore, the moisture-curable urethane hot melt composition of the present invention can be used for building interior materials such as lower leg doors, closet doors, kitchen doors, frame materials, frame materials, peripheral edges, lumbers, counter tables, furniture top plates, etc. It can be particularly preferably used as an adhesive used for wrapping furniture.

The moisture-curable urethane hot melt composition of the present invention contains a polyol (A) containing a polyester polyol (A-1) represented by the following formula (1) and a polyisocyanate (B-1) containing a polyfunctional isocyanate (B-1). ) And a urethane prepolymer having an isocyanate group which is a reaction product of.

（式（１）中、Ｒ^１及びＲ^２は、それぞれ独立して炭素原子数が偶数である直鎖のアルキレン基を示し、Ｒ^１及びＲ^２の有する炭素原子数の合計は１２以上であり、ｎは３〜４０整数を示す。）

(In the formula (1), R ¹ and R ² each independently represent a linear alkylene group having an even number of carbon atoms, and the total number of carbon atoms of ^{R 1} and R ^{2 is 12 or more.} , N represents an even number of 3 to 40.)

It is essential to use the polyester polyol (A-1) represented by the formula (1) in order to obtain excellent initial strength.

^{R 1} in the formula (1) is a linear alkylene group having an even number of carbon atoms, and may be appropriately selected within a range in which the total number of carbon atoms of ^{R 1} and R ^{2 is 12 or more.} can. Among them, a linear alkylene group having an even number of carbon atoms, preferably 4 or more, more preferably 4 to 12, and even more preferably 4 to 8, is preferable from the viewpoint of obtaining more excellent initial strength.

R ² in the formula (1), the a linear alkylene group having the number of carbon atoms independently is an even number and R ^1, the total number of carbon atoms possessed by R ¹ and R ² is 12 or greater It can be selected as appropriate within the above range. Above all, a linear alkylene group having an even number of carbon atoms of 4 or more, more preferably 6 to 12, is preferable from the viewpoint of obtaining more excellent initial strength.

N in the formula (1) represents an integer of 3 to 40. Among them, 5 to 25 is preferable, and 9 to 15 is more preferable, from the viewpoint of obtaining more excellent initial strength.

As a specific example of the polyester polyol (A-1), for example, a condensation reaction product of a linear diol having an even number of carbon atoms and a polybasic acid having an even number of carbon atoms can be used.

As the linear diol having an even number of carbon atoms, for example, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and the like may be used. Can be done. These diols may be used alone or in combination of two or more. Among these, one or more diols selected from the group consisting of 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol should be used from the viewpoint of obtaining more excellent initial strength. Is preferable.

As the polybasic acid having an even number of carbon atoms, for example, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dodecamethylenedicarboxylic acid and the like can be used. These tabasic acids may be used alone or in combination of two or more. Among these, it is preferable to use one or more polybasic acids selected from the group consisting of adipic acid, sebacic acid, and dodecanedioic acid from the viewpoint of obtaining more excellent initial strength, and it is preferable to use sebacic acid and / or dodecanni. It is more preferable to use an acid.

The number average molecular weight of the polyester polyol (A-1) is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 8,000, from the viewpoint of obtaining more excellent initial strength. The range of 800 to 5,000 is more preferable. The number average molecular weight of the polyester polyol (A-1) is a value 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" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 This "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (Differential Refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was prepared 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

The content of the polyester polyol (A-1) is preferably in the range of 10 to 85% by mass in the polyol (A), preferably in the range of 20 to 70% by mass, from the viewpoint of obtaining more excellent initial strength. Is more preferable.

As the polyol (A), in addition to the polyester polyol (A-1), for example, a polyether polyol such as polyethylene glycol, polypropylene glycol, and a polyether polyol; an aliphatic polyester oar other than the above (A-1), and aroma. Polyester polyols such as group polyester polyols; polyols such as polycarbonate polyols, acrylic polyols and dimerdiols can be used. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use one or more polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and aromatic polyester polyols from the viewpoint of obtaining more excellent melt viscosity and hydrolysis resistance. , Polycarbonate Glylicol, Polycarbonate Polyol, and Aromatic Polyester Polyol are more preferred.

The number average molecular weight of the polyols other than the polyester polyol (A-1) is in the range of 500 to 20,000 from the viewpoint of obtaining more excellent mechanical strength of the coating film and hydrolysis resistance. Is preferable, and the range of 700 to 8,000 is more preferable. The number average molecular weight of these polyols shows the values obtained by measuring in the same manner as the polyester polyol (A-1).

As the polyisocyanate (B), it is essential to use a polyfunctional isocyanate (B-1) in order to obtain excellent hydrolysis resistance.

Examples of the polyfunctional isocyanate (B-1) include an isocyanurate compound (B-1-1) which is a trimer of a diisocyanate (B-2); an adduct compound; a buretto compound; an allophanate compound; and a polymethylene polyphenyl. A polyfunctional polyisocyanate such as polyisocyanate (B-1-2) can be used. These polyfunctional polyisocyanates may be used alone or in combination of two or more. In the present invention, the "polyfunctional" of the "polyfunctional polyisocyanate (B-1)" means that it has three or more isocyanate groups.

Examples of the diisocyanate (B-2) include aromatic polyisocyanates such as diphenylmethane diisocyanate, phenylenedi isocyanate, tolylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and xylylene diisocyanate. An aliphatic diisocyanate such as isocyanate or tetramethylxylylene diisocyanate or a diisocyanate such as an alicyclic polyisocyanate can be used. These diisocyanates may be used alone or in combination of two or more.

As the polyfunctional isocyanate (B-1), it is preferable to use an isocyanurate compound (B-1-1) in order to obtain more excellent hydrolysis resistance, and the isocyanurate compound (b-1-1) is preferable. ), It is more preferable to use an aliphatic isocyanurate compound.

The content of the isocyanurate compound (B-1) is preferably in the range of 0.1 to 30% by mass in the polyisocyanate (B) from the viewpoint of obtaining more excellent hydrolysis resistance. The range of 5 to 25% by mass is more preferable, and the range of 10 to 20% by mass is further preferable.

Further, as the polyfunctional isocyanate (B-1), an isocyanurate compound (B-1-1) and a polymethylene polyphenyl polyisocyanate (B-1) are further obtained in order to obtain further excellent hydrolysis resistance. It is preferable to use in combination with -2).

The polymethylene polyphenyl polyisocyanate (B-1-2) is specifically represented by the following formula (2), and preferably represents an integer of 1 to 5 in the formula (2). It is a thing.

（式（２）中、ｎは１以上の整数である。）

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

Examples of the polymethylene polyphenyl polyisocyanate (B-1-2) include "Millionate MR-100" and "Millionate MR-200" manufactured by Tosoh Corporation, and "WANNAME PM-200" manufactured by Manka Japan Co., Ltd. "WANNAME PM-400", "Cosmonate M-1500" manufactured by Mitsui Chemicals, Inc., "Boranate M-595" manufactured by Dow Chemicals Co., Ltd., etc. can be obtained as commercial products.

The content of the polyfunctional polyisocyanate (B-1-2) is in the range of 0.1 to 30% by mass in the polyisocyanate (B) from the viewpoint of obtaining more excellent hydrolysis resistance. It is preferably in the range of 5 to 25% by mass, more preferably in the range of 10 to 20% by mass.

As the mass ratio of the isocyanurate compound (B-1-1) to the polyfunctional polyisocyanate (B-1-2), more excellent melt viscosity, initial strength, and hydrolysis resistance can be obtained. , 30/70 to 70/30, more preferably 40/60 to 60/40.

As the polyisocyanate (B), the diisocyanate (B-2) can be used in addition to the polyfunctional isocyanate (B-1). As the diisocyanate (B-2), it is preferable to use diphenylmethane diisocyanate from the viewpoint of obtaining more excellent adhesiveness and hydrolysis resistance.

The urethane prepolymer having an isocyanate group is obtained by reacting the polyol (A) with the polyisocyanate (B), and is in the air or in a housing or an adherend to which the urethane prepolymer is applied. It has an isocyanate group at the end of the polymer or in the molecule that can react with the water present in the polymer to form a crosslinked structure.

As a method for producing the urethane prepolymer, for example, the polyisocyanate (B) is dropped into a reaction vessel containing the polyol (A) and then heated, and the isocyanate group contained in the polyisocyanate (B) is described as described above. It can be produced by reacting with the hydroxyl group of the polyol (A) under excessive conditions.

The initial strength can be further improved as the equivalent ratio ([isocyanate group / hydroxyl group]) of the isocyanate group of the polyisocyanate (B) to the hydroxyl group of the polyol (A) when producing the urethane prepolymer. From the viewpoint of obtaining an appropriate melt viscosity, the range is preferably in the range of 1.1 to 5, and more preferably in the range of 1.5 to 3.

When producing the urethane prepolymer, a urethanization catalyst can be used if necessary. The urethanization catalyst can be added as appropriate at any stage of the reaction.

As the urethanization catalyst, for example, a nitrogen-containing compound such as triethylamine, triethylenediamine, N-methylmorpholine; a metal salt such as potassium acetate, zinc stearate, tin octylate; an organic metal compound such as dibutyltin dilaurate is used. be able to. These catalysts may be used alone or in combination of two or more.

The isocyanate group content of the urethane prepolymer obtained by the above method (hereinafter, abbreviated as "NCO%") is preferably in the range of 0.5 to 10% from the viewpoint of initial strength. A range of 7.5% is more preferred. The NCO% of the urethane prepolymer is based on JISK1603-1: 2007 and indicates a value measured by a potentiometric titration method.

The melt viscosity of the urethane prepolymer is preferably in the range of 1,000 to 20,000 mPa · s, preferably from 2,000 to 2,000, from the viewpoint of further improving workability and initial strength. It is more preferably in the range of 13,000 mPa · s. The melt viscosity at 120 ° C. indicates a value measured by a cone plate viscometer (manufactured by ICI).

The moisture-curable polyurethane hot-melt composition of the present invention may be composed only of the urethane prepolymer, but may contain other additives as necessary.

As the other additives, for example, antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, fluorescent whitening agents, silane coupling agents, waxes, thermoplastic resins and the like are used. Can be done. These additives may be used alone or in combination of two or more.

The moisture-curable urethane hot-melt composition of the present invention obtained by the above method is excellent in initial strength and hydrolysis resistance. Therefore, the moisture-curable urethane hot melt composition of the present invention can be used for building interior materials such as lower leg doors, closet doors, kitchen doors, frame materials, frame materials, peripheral edges, lumbers, counter tables, furniture top plates, etc. It can be particularly preferably used as an adhesive used for wrapping furniture.

As a method of wrapping using the moisture-curable polyurethane hot-melt composition of the present invention, for example, the moisture-curable polyurethane hot-melt composition is melted at a temperature of 100 to 120 ° C., and then melted on a substrate. A method of applying the moisture-curable polyurethane hot melt composition and then crimping the sheet or film with a known wrapping device can be mentioned.

Examples of the method for applying the melted moisture-curable polyurethane hot melt composition include a method using a knife coater, a head coater, a slit coater, a T-die coater, a roll coater, and the like.

The thickness of the coating material of the moisture-curable polyurethane hot melt composition is appropriately determined depending on the intended use, and is, for example, in the range of 1 to 200 μm.

As the base material, for example, natural wood, plywood, MDF (medium density fiberboard), wood base material such as particle board; metal base material such as iron; plastic board, aluminum and the like can be used. The base material may have a portion having a complicated shape such as a groove portion, an R portion, and an inverted R portion.

As the sheet or film, for example, a sheet or film obtained by using a resin such as polyester, polyamide, polystyrene, polycarbonate, vinyl chloride, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene, polypropylene, etc .; paper; metal. Foil; a protruding plate or the like can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
In a four-necked flask equipped with a thermometer, a stirrer, and an inert gas inlet, a polyester polyol (reactant of 1,6-hexanediol and dodecanedioic acid, number average molecular weight: 3,500, hereinafter "HG / DDA" (Abbreviated as "PPG") is charged in 33 parts by mass and polypropylene glycol (number average molecular weight: 2,000, hereinafter abbreviated as "PPG") is charged in 48 parts by mass and heated under reduced pressure at 100 ° C. to increase the water content in the flask. Was dehydrated to 0.05% by mass or less.
Next, the inside of the flask was cooled to 70 ° C., and 13 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") melted at 70 ° C., polymethylene polyphenyl polyisocyanate (manufactured by Tosoh Corporation, """MillionateMR-200", hereinafter abbreviated as "Polymeric MDI") 3 parts by mass and 3 parts by mass of an isocyanurate compound of hexamethylene diisocyanate (hereinafter, abbreviated as "HDI nurate") are added, and NCO is added under a nitrogen atmosphere. A urethane prepolymer was obtained by reacting at 100 ° C. for about 3 hours until the% became constant, and a moisture-curable polyurethane hot melt composition was obtained.

[Examples 2 to 5 and Comparative Examples 1 to 2]
A urethane prepolymer was obtained in the same manner as in Example 1 except that the types and amounts of the polyol (A) and the polyisocyanate (B) used were changed as shown in Table 1, to obtain a moisture-curable polyurethane hot melt composition. ..

[Evaluation method of initial strength]
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 so as to have a thickness of 50 μm. MDF (medium density fiberboard) was laminated on the coated layer and crimped with a crimping roller. After 5 minutes from crimping, a load of 75 g was applied to a 25 mm wide test piece in the 90 ° direction, and the peeling length (mm) of the polyethylene terephthalate sheet after 15 minutes was measured. evaluated.
"○": Peeling length is less than 5 mm "×": Peeling length is 5 mm or more

[Evaluation method of hydrolysis resistance]
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 polyliethylene terephthalate sheet using an applicator so as to have a thickness of 50 μm. MDF was laminated on the coating layer and crimped with a crimping roller. The obtained test piece was cured under the conditions of 23 ° C. and 50% humidity for 5 days, and then polyethylene was applied to a width of 25 mm and a load of 70 g in the 90 ° direction under an atmosphere of 85 ° C. and 85% humidity. The number of days until the terephthalate sheet peeled off by 40 mm or more was measured and evaluated as follows.
"○": 20 days or more "×": less than 20 days

The abbreviations in Table 1 indicate the following.
"HG / SEBA": reaction product of 1,6-hexanediol and sebacic acid, number average molecular weight: 3,500
"HG / AA": reaction product of 1,6-hexanediol and adipic acid, number average molecular weight: 3,500
"PEs2": Ethylene glycol, neopentyl glycol, isophthalic acid, and terephthalic acid reactants, number average molecular weight: 2,600

It was found that Examples 1 to 5, which are the moisture-curable polyurethane hot melt compositions of the present invention, are excellent in initial strength and hydrolysis resistance.

On the other hand, Comparative Example 1 was an embodiment in which the isocyanurate compound (B-1) was not contained as the polyisocyanate (B), but the hydrolysis resistance was poor.

Comparative Example 2 is an embodiment in which another polyester polyol is used instead of the specific polyester polyol (A-1), but the initial strength is poor.

Claims (2)

Urethane having an isocyanate group which is a reaction product of a polyol (A) containing a polyester polyol (A-1) represented by the following formula (1) and a polyisocyanate (B) containing a polyfunctional isocyanate (B-1). Contains prepolymer,
The polyol (A) further contains a polyol other than the polyester polyol (A-1).
The polyisocyanate (B) further contains a diisocyanate (B-2).
The polyfunctional isocyanate (B-1) contains an isocyanurate compound (B-1-1) and a polymethylene polyphenyl polyisocyanate (B-1-2) .
The content of the isocyanurate compound (B-1-1) is in the range of 0.1 to 30% by mass in the polyisocyanate (B).
A moisture-curable polyurethane hot-melt composition characterized in that the content of the polymethylene polyphenyl polyisocyanate (B-1-2) is in the range of 0.1 to 30% by mass in the polyisocyanate (B). ..

(In the formula (1), R ¹ and R ² each independently represent a linear alkylene group having an even number of carbon atoms, and the total number of carbon atoms of ^{R 1} and R ^{2 is 12 or more.} , N represents an even number from 3 to 40.) The isocyanurate compound (B-1-1) is, according to claim 1 Symbol placement moisture-curable polyurethane hot-melt composition of an aliphatic isocyanurate compound.