Moisture-curing reactive hot melt adhesive

Abstract

To provide a moisture-curable reactive hot melt adhesive which, while maintaining good adhesiveness and melt viscosity, has high curability due to a short tack-free time, has excellent elasticity and impact resistance due to a high coefficient of elasticity, is less likely to deteriorate the substrate due to low moisture permeability, and absorbs a phthalic acid ester restrainedly.SOLUTION: Provided is a moisture-curable reactive hot melt adhesive, comprising an isocyanate-terminated urethane prepolymer which is obtained by reacting a polyol compound (A) containing a polycarbonate polyol (a1-1) derived from a sugar alcohol and a polyisocyanate compound (B).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a moisture-curable reactive hot melt adhesive. [Background technology]

[0002] In general, hot melt compositions are solvent-free, environmentally friendly, can be cured in a short time, and are very easy to handle, which makes it possible to improve the working environment at manufacturing sites. Therefore, hot melt compositions are widely used in precision fields such as automobiles and electrical appliances, as well as in the construction field.

[0003] In the past, the applicant invented a moisture-curing reactive hot melt adhesive containing an isocyanate-terminated urethane prepolymer obtained by reacting a polyol composition (A) containing an amorphous polyester polyol (a1) having an aromatic dicarboxylic acid as a constituent unit and a liquid polyester polyol (a2) having an aromatic dicarboxylic acid as a constituent unit, the total of (a1) and (a2) being 50% by weight or more relative to the total polyol, with a polyfunctional isocyanate compound (B) (Patent Document 1). This hot melt adhesive had good adhesion to aromatic group-containing substrates, such as polyester sheets, even at low temperatures, and was useful for laminating decorative polyester sheets, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-255187 A

[0005] Conventionally, moisture-curing reactive hot melt adhesives have been used in the manufacturing process of building materials. Specifically, they are used when bonding a plastic surface material to a wood-based substrate. Here, the moisture-curing reactive hot melt adhesive shown in Patent Document 1 has a relatively high moisture permeability, so that the wood-based substrate may gradually deform due to absorption of moisture passing through the bonding surface, and there is room for improvement. In addition, when a polyvinyl chloride resin-based surface material is bonded, the phthalate ester added to the resin as a plasticizer gradually seeps out and is absorbed by the bonding surface, which may cause a phenomenon in which the adhesive strength is reduced, and further improvement is required. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide a moisture-curing reactive hot melt adhesive that has high curing properties due to a short tack-free time, excellent elasticity and impact resistance due to a high elastic modulus, resistance to deterioration of the substrate due to low moisture permeability, and suppressed absorption of phthalate esters, all while maintaining good adhesion and melt viscosity. [Means for solving the problem]

[0007] The present invention is a moisture-curable reactive hot melt adhesive characterized by containing an isocyanate-terminated urethane prepolymer obtained by reacting a polyol compound (A) containing a polycarbonate polyol (a1-1) derived from a sugar alcohol with a polyisocyanate compound (B). Effect of the Invention

[0008] The moisture-curable reactive hot melt adhesive of the present invention has the following advantages: while maintaining good adhesion and melt viscosity, it has a short tack-free time resulting in high curing ability, a high elastic modulus resulting in excellent elasticity and impact resistance, low moisture permeability resulting in less deterioration of the substrate, and suppressed absorption of phthalate esters. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Polyol compound> In the present invention, a polyol compound (A) is used. Examples of the polyol compound include polycarbonate polyol (a1), polyester polyol (a2), polyether polyol (a3), and polybutadiene polyol (a4).

[0010] The polycarbonate polyol (a1) is a polyol compound having a carbonate structure as a skeleton, and can generally be obtained by reacting an alcohol having two or more hydroxyl groups with a carbonate ester having two or more carbonate groups.

[0011] In particular, in the present invention, polycarbonate polyol (a1-1) derived from sugar alcohol is used. The (a1-1) component uses a sugar alcohol or its anhydride as an alcohol having two or more hydroxyl groups. The sugar alcohol can be obtained by reducing a carbonyl group in the sugar structure, and the anhydride can be obtained by dehydrating and condensing the sugar alcohol. Examples of the sugar alcohol include lactitol, maltitol, mannitol, and sorbitol, and examples of the anhydride include isosorbide obtained by dehydrating and condensing sorbitol.

[0012] In particular, it is preferable that the component (a1-1) has a structure represented by formula (1) as a structural unit. [ka]

[0013] The inventors of the present invention have found that by using the component (a1-1) as a polyol compound, while maintaining good adhesion and melt viscosity, the tack-free time is short so that curability is high, the elastic modulus is high so that elasticity and impact resistance are excellent, the moisture permeability is low so that the substrate is less likely to deteriorate, and absorption of phthalate esters is suppressed, and have completed the present invention.

[0014] Examples of carbonate esters having two or more carbonate groups include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, and dicaprylyl carbonate.

[0015] The number average molecular weight of the component (a1-1) is preferably from 300 to 10,000, more preferably from 400 to 8,000, and particularly preferably from 500 to 6,000.

[0016] Specific examples of the (a1-1) component include HS0830B (product name, manufactured by Mitsubishi Chemical Corporation, isosorbide-based, number average molecular weight: 800) and HS0840H (product name, manufactured by Mitsubishi Chemical Corporation, isosorbide-based, number average molecular weight: 800).

[0017] Furthermore, a polycarbonate polyol (a1-2) other than the component (a1-1) can be used as long as the effects of the present invention are not impaired.

[0018] The (a1-2) component can be obtained by reacting an alcohol having two or more hydroxyl groups (excluding sugar alcohols and their anhydrides) with a carbonate ester having two or more carbonate groups.

[0019] Examples of alcohols having two or more hydroxyl groups (excluding sugar alcohols and their anhydrides) include chemical substances having about 2 to 24 carbon atoms, such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,2-, 1,3-, or 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,3-, 1,4-, 1,6-, or 2,5-hexanediol, 1,2- or 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,18-octadecanediol, and 1,20-eicosanediol.

[0020] Examples of carbonate esters having two or more carbonate groups include the compounds mentioned above.

[0021] Furthermore, in the present invention, for the purpose of improving the tensile strength, a polyol compound other than the polycarbonate polyol (a1) can be used.

[0022] In the present invention, polyester polyol (a2) can be used. The (a2) component is a polyol compound having an ester structure as a skeleton, and can be divided into crystalline and non-crystalline ones. The (a2) component can be obtained by condensation polymerization of alcohols having two or more hydroxyl groups and carboxylic acids having two or more carboxyl groups.

[0023] Examples of the alcohols having two or more hydroxyl groups include the compounds mentioned above.

[0024] Examples of carboxylic acids having two or more carboxyl groups include chemical substances having about 2 to 24 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, methylsuccinic acid, dimethylmalonic acid, β-methylglutaric acid, ethylsuccinic acid, isopropylmalonic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, hexadecanedicarboxylic acid, octadecanedicarboxylic acid, eicosanedicarboxylic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, and terephthalic acid.

[0025] The number average molecular weight of the component (a2) is preferably from 500 to 15,000, more preferably from 800 to 12,000, and particularly preferably from 1,000 to 10,000.

[0026] The blending ratio of the (a2) component is preferably 30 to 800 parts by weight, more preferably 50 to 700 parts by weight, and particularly preferably 100 to 600 parts by weight, per 100 parts by weight of the (a1-1) component.

[0027] Specific examples of the (a2) component include HS2H-201AP (product name, Toyokuni Oil Mills, 1,6-hexanediol-based, number average molecular weight: 2,000), HS2H-451A (product name, Toyokuni Oil Mills, 1,6-hexanediol-based, number average molecular weight: 4,500), HS2E-581A (product name, Toyokuni Oil Mills, glycol-based, number average molecular weight: 5,500), HS Polyol 1000 (product name, Toyokuni Oil Mills, aromatic, number average molecular weight: 3,000), and P-7730 (product name, Evermore, glycol-based, number average molecular weight: 3,000).

[0028] In the present invention, polyether polyol (a3) ​​can be used. The (a3) ​​component is a polyol compound having an ether structure as a skeleton. The (a3) ​​component can be obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc. to the above-mentioned alcohols having two or more hydroxyl groups. Specific examples of chemical substances include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

[0029] The number average molecular weight of the component (a3) ​​is preferably from 300 to 10,000, more preferably from 400 to 8,000, and particularly preferably from 500 to 5,000.

[0030] The blending ratio of the (a3) ​​component is preferably 10 to 300 parts by weight, more preferably 30 to 250 parts by weight, and particularly preferably 50 to 200 parts by weight, per 100 parts by weight of the (a1-1) component.

[0031] Specific examples of the (a3) ​​component include PTMEG2000 (product name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, number average molecular weight: 2,000), Hiflex D-1000 (product name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polypropylene glycol, number average molecular weight: 1,000), and Hiflex D-2000 (product name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polypropylene glycol, number average molecular weight: 2,000).

[0032] In the present invention, a polybutadiene polyol (a4) can be used. The (a4) component is a polyol having a butadiene structure as the skeleton.

[0033] The number average molecular weight of the component (a4) is preferably from 1,000 to 20,000, more preferably from 1,200 to 15,000, and particularly preferably from 1,500 to 10,000.

[0034] The blending ratio of the (a4) component is preferably 10 to 200 parts by weight, more preferably 30 to 150 parts by weight, and particularly preferably 50 to 120 parts by weight, per 100 parts by weight of the (a1-1) component.

[0035] A specific example of the component (a4) is G-3000 (product name, manufactured by Nippon Soda Co., Ltd., number average molecular weight: 3,000).

[0036] <Polyisocyanate compounds> In the present invention, a polyisocyanate compound (B) is used. The (B) component preferably has two or more isocyanate groups at its terminals. The types of the (B) component include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0037] Specific examples of the compound of component (B) include methylene diphenyl diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), and hydrogenated products thereof.

[0038] When the polyol compound (A) containing the component (a1-1) is reacted with the polyisocyanate compound (B), the molar ratio of hydroxyl groups of the polyol compound to isocyanate groups of the polyisocyanate compound is preferably 1:1-5, more preferably 1:1.1-4, and particularly preferably 1:1.2-3.

[0039] When using multiple polyol compounds in producing an isocyanate-terminated urethane prepolymer, it is preferable to add a catalyst as necessary, thoroughly mix them, and then add the polyisocyanate compound (B) to react them.

[0040] The moisture-curable reactive hot melt adhesive according to the present invention may contain other components such as fillers such as calcium carbonate, talc, and clay, and various additives such as antioxidants and preservatives. EXAMPLES

[0041] <Examples and Comparative Examples> The raw materials other than the polyisocyanate compound were placed in a separable flask equipped with a stirrer, temperature controller, and vacuum pump in the formulation shown in Table 1, and after stirring and dehydrating at 120°C under reduced pressure for 1 hour, the polyisocyanate compound was added and stirred and reacted at 100°C under a nitrogen atmosphere for 1 hour and at 100°C under reduced pressure for 1 hour to obtain a moisture-curable reactive hot melt adhesive according to the present invention. Here, the values ​​in Table 1 represent parts by weight. The compounds used are shown below. HS0830B (product name): Mitsubishi Chemical Corporation, polycarbonate polyol (isosorbide type), number average molecular weight: 800 NL1010DB (product name): Mitsubishi Chemical Corporation, polycarbonate polyol (1,10-decanediol type), number average molecular weight: 1,000 NL1030B (product name): Mitsubishi Chemical Corporation, polycarbonate polyol (neopentyl glycol type), number average molecular weight: 1,000 HS2H-451A (product name): Toyokuni Oil Co., Ltd., polyester polyol (1,6-hexanediol type), number average molecular weight: 4,500 HS Polyol 1000 (product name): Toyokuni Oil Co., Ltd., polyester polyol (aromatic type), number average molecular weight: 3,000 P-7730 (product name): Evermore Corporation, polyester polyol (glycol type), number average molecular weight: 3,000 PTMEG2000 (product name): Mitsubishi Chemical Corporation, polyether polyol (polytetramethylene ether glycol), number average molecular weight: 2,000 Filler: Talc (average particle size: 5 μm) Polyisocyanate compound: A mixture of 4,4'-methylenediphenyl diisocyanate and 2,4'-methylenediphenyl diisocyanate (weight ratio 1:1)

[0042] [Table 1]

[0043] The moisture-curable reactive hot melt adhesives obtained in the above examples were subjected to the following physical property evaluations. The results are shown in Table 2.

[0044] <Melt viscosity> Using a Brookfield viscometer, the moisture-curing reactive hot melt adhesive was melted at 120°C, and rotation was started at 10 rpm with a measurement temperature of 120°C, spindle No. 29, and the melt viscosity (mPa s) was measured 15 minutes later. Measurements of 30,000 mPa s or less were rated as ◯, and measurements of more than 30,000 mPa s were rated as ×.

[0045] <Tuck free time> The moisture-curing reactive hot melt adhesive was melted at 120°C and a coating film was produced using an applicator to a thickness of 100 μm. The film was then left to stand at room temperature (23°C) and the time until the tack disappeared when touched with a finger was measured.

[0046] <Adhesiveness> The moisture-curing reactive hot melt adhesive was melted at 120°C and applied at 80 g / m2 onto an olefin sheet using an applicator. 2 After coating, the sheet was immediately laminated to a wood-based substrate (MDF) and left to harden at room temperature (23°C) for one week. The olefin sheet was then pulled at 180° by peeling and the state of destruction was confirmed.

[0047] <Tensile test> The moisture-curing reactive hot melt adhesive was melted at 120°C to prepare a sheet with a thickness of 500 μm, which was then left to harden at room temperature (23°C) for one week. After that, it was processed into a dumbbell size No. 8 and the breaking stress (N / mm 2 ), elastic modulus (N / mm 2 ) was measured.

[0048] <Moisture permeability> The moisture-curing reactive hot melt adhesive was melted at 120°C to prepare a coating film with a thickness of 175 μm, which was then left to stand at room temperature (23°C) for one week to cure. Thereafter, the moisture permeability was measured at 40°C and 90% RH in accordance with JIS Z 0208.

[0049] <Plasticizer resistance> The moisture-curing reactive hot melt adhesive was melted at 120°C, and a coating film with a thickness of 125 μm was prepared using an applicator, and the coating film was left to harden at room temperature (23°C) for one week. Then, a test piece of 30 mm x 40 mm was prepared, placed in a glass bottle (100 ml) with a lid, and diisononyl phthalate was poured into the bottle until the test piece was completely immersed. After the bottle was closed, the test piece was left to stand in a thermostatic bath (40°C) for one week. The test piece was then removed, and the diisononyl phthalate adhering to the surface was wiped off with a rag, and the weight increase rate was calculated using the following formula. Weight increase rate (%) = (weight after test - weight before test) / weight before test x 100

[0050] [Table 2]

Claims

1. A composition comprising an isocyanate-terminated urethane prepolymer obtained by reacting a polyol compound (A) containing 30 to 800 parts by weight of a polyester polyol (a2) with 100 parts by weight of an isosorbide-based polycarbonate polyol (a1-1) with a polyisocyanate compound (B), A moisture-curable reactive hot melt adhesive, characterized in that the isosorbide-based polycarbonate polyol (a1-1) has two functional groups.

2. 2. The moisture-curing reactive hot melt adhesive according to claim 1, which is used for bonding polyvinyl chloride resin surface materials.

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