JP7347041B2 - Moisture-curable polyurethane hot melt resin composition - Google Patents

Description

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

Since moisture-curing polyurethane hot melt adhesives are solvent-free, they have been extensively researched as environmentally friendly adhesives for fiber bonding and construction material lamination, and are widely used in industry.

The moisture-curable polyurethane hot melt adhesive develops its final adhesive strength through moisture curing of the isocyanate groups of the urethane prepolymer, which is its main ingredient. Desired.

However, the needs for the use of the moisture-curing polyurethane hot melt adhesive are expanding to include the assembly of electronic materials, and there is a growing need for adhesion to various base materials such as engineering plastics, metals, and rubber. (For example, see Patent Document 1.)

JP2018-44944A

The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot melt resin composition that has excellent adhesiveness to metal substrates.

The present invention provides a moisture-curable polyurethane hot water curable polyurethane hot water curable polyurethane hot water curable polyurethane hot polyurethane prepolymer (i) having an isocyanate group made from a polyol (A) and a polyisocyanate (B), and containing a metal organic compound (ii). A melt resin composition is provided.

The moisture-curable polyurethane hot melt resin composition of the present invention has excellent adhesiveness to metal substrates. Therefore, the moisture-curable polyurethane hot melt resin composition of the present invention can be particularly suitably used as an adhesive used in assembling electronic materials.

The moisture-curable polyurethane hot melt resin composition of the present invention contains a urethane prepolymer (i) having an isocyanate group and a metal organic compound (ii).

The urethane prepolymer (i) has isocyanate groups made from polyol (A) and polyisocyanate (B). Moreover, it is preferable that the urethane prepolymer (i) does not have any other reactive groups other than the isocyanate group.

As the polyol (A), polyether polyol (a1), polyacrylic polyol (a2), crystalline polyester polyol (a3), amorphous polyester polyol (a4), polycarbonate polyol, polybutadiene polyol, dimer diol, etc. are used. be able to. These polyols may be used alone or in combination of two or more. Among these, polyether polyol (a1), polyacrylic polyol (a2), crystalline polyester polyol (a3) and It is preferable to use one or more polyols selected from the group consisting of crystalline polyester polyols (a4), including polyether polyols (a1), polyacrylic polyols (a2), crystalline polyester polyols (a3), and amorphous polyols. It is more preferable to use all of the polyester polyol (a4). However, the improvement in adhesion to metal substrates, which is an effect of the present invention, is mainly derived from the metal-organic compound (ii) described below, and the polyol (A) may be used appropriately depending on the application. I can do it.

The polyether polyol (a1) is preferably a polyoxyalkylene polyol, and if necessary, one or more compounds having two or more active hydrogen atoms are used as an initiator to form a cyclic ether such as an alkylene oxide. Those obtained by ring-opening polymerization can be used.

The number of carbon atoms in the cyclic ether is preferably 2 to 10, more preferably 2 to 6, and still more preferably 2 to 4. The hydrogen atoms contained in the cyclic ether may be substituted with halogen atoms. As the cyclic ether, one type or two or more types can be used, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, alkyl Tetrahydrofuran and the like can be used.

As the initiator, one type or two or more types can be used, for example, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6- Compounds with two active hydrogen atoms such as hexanediol, neopentyl glycol, water; glycerin, diglycerin, trimethylolethane, trimethylolpropane, hexanetriol, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, pentaerythritol, Compounds having three or more active hydrogen atoms such as sugars can be used.

The polyether polyol (a1) is one or more polyether polyols selected from the group consisting of polypropylene glycol, polyoxypropylene triol, polytetramethylene glycol, and polyoxyethylene polyoxypropylene glycol, among those listed above. It is preferable to use

The number average molecular weight of the polyether polyol (a1) is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 5,000, from the standpoint of obtaining even better adhesiveness and flexibility. The number average molecular weight of the polyether polyol (a1) is a value measured by gel permeation chromatography (GPC).

As the polyacrylic polyol (a2), for example, a polymer of a (meth)acrylic compound that essentially contains a (meth)acrylic compound having a hydroxyl group can be used. In the present invention, "(meth)acrylic compound" refers to one or both of a methacrylic compound and an acrylic compound, and "(meth)acrylate" refers to one or both of methacrylate and acrylate.

As the (meth)acrylic compound having a hydroxyl group, for example, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc. can be used. These compounds may be used alone or in combination of two or more.

Examples of other (meth)acrylic compounds include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate. 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 - (Meth)acrylic compounds having a fluorine atom such as octafluoropentyl (meth)acrylate, 2-(perfluorooctyl)ethyl (meth)acrylate; isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, cydiclopentanyl ( (Meth)acrylic compounds with alicyclic structures such as meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate; polyethylene glycol mono(meth)acrylate, methoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxytri (Meth)acrylic compounds having ether groups 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, etc. can be used. These compounds may be used alone or in combination of two or more. Among these, (meth)acrylic compounds and (meth)acrylic acid alkyl esters having a hydroxyl group are preferred from the viewpoint of obtaining even better waterproofness, adhesiveness, and open time, and 2-hydroxyethyl (meth)acrylic acid alkyl esters are preferred. More preferred are acrylate, methyl (meth)acrylate and n-butyl (meth)acrylate.

The number average molecular weight of the acrylic polyol (a2) is preferably in the range of 5,000 to 100,000, and 10,000 to 30, from the viewpoint of obtaining even better waterproof properties, adhesive properties, and open time. A range of 000 is more preferable. The number average molecular weight of the acrylic polyol (a2) is a value measured by gel permeation chromatography (GPC).

The glass transition temperature of the acrylic polyol (a2) is preferably in the range of 30 to 120°C, more preferably in the range of 50 to 80°C, from the standpoint of obtaining even better waterproof properties, adhesive properties, and open time. . The glass transition temperature of the acrylic polyol (a2) is a value measured by DSC in accordance with JIS K 7121-1987. ), the temperature was raised to (Tg + 50 °C) at a heating rate of 10 °C/min, held for 3 minutes, then rapidly cooled, and the midpoint glass transition temperature (Tmg) read from the obtained differential thermal curve is shown. .

When using the acrylic polyol (a2), the amount to be used is 10 to 250 parts by mass based on 100 parts by mass of the ether polyol (a1) in order to obtain even better waterproof properties, open time, and adhesive properties. A range of parts by weight is preferred, a range of 15 to 200 parts by weight is more preferred, and a range of 20 to 150 parts by weight is even more preferred.

As the crystalline polyester polyol (a3), for example, a reaction product of a compound having a hydroxyl group and a polybasic acid can be used. In the present invention, "crystalline" refers to a property in which a peak of heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimeter) measurement in accordance with JISK7121:2012, and "amorphous" indicates that the peak cannot be confirmed.

As the compound having a hydroxyl group, for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, etc. may be used. I can do it. 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 increasing crystallinity and obtaining even better waterproofness and adhesiveness. .

As the polybasic acid, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, etc. can be used. These compounds may be used alone or in combination of two or more.

The number average molecular weight of the crystalline polyester polyol (a3) is preferably in the range of 500 to 10,000, and preferably in the range of 1,000 to 4,000, from the viewpoint of obtaining even better waterproof properties and adhesive properties. More preferred. The number average molecular weight of the crystalline polyester polyol (a3) is a value measured by gel permeation chromatography (GPC).

When using the crystalline polyester polyol (a3), the amount used is based on 100 parts by mass of the ether polyol (a1), from the viewpoint of obtaining even better flexibility, adhesiveness, and open time. The range is preferably from 20 to 600 parts by weight, and more preferably from 40 to 400 parts by weight.

As the amorphous polyester polyol (a4), for example, the following reaction product of a compound having a hydroxyl group and a polybasic acid can be used.

Examples of the compound having a hydroxyl group include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentane. Diol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerin, trimethylolpropane; bisphenol A, bisphenol F, alkylene oxide adducts thereof, and the like can be used. These compounds may be used alone or in combination of two or more.

As the polybasic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, etc. may be used. I can do it. These compounds may be used alone or in combination of two or more.

The number average molecular weight of the amorphous polyester polyol (a4) is preferably in the range of 500 to 10,000, and 1,000 to 4 The range of ,000 is more preferable, and the range of 1,000 to 3,000 is even more preferable. The number average molecular weight of the amorphous polyester polyol (a4) is a value measured by gel permeation chromatography (GPC).

The glass transition temperature of the amorphous polyester polyol (a4) is preferably in the range of -70 to 0°C from the viewpoint of obtaining even better waterproof properties, adhesive properties, and flexibility. The glass transition temperature of the amorphous polyester polyol (a4) is the same as the method for measuring the glass transition temperature (Tg) of the polyacrylic polyol (a2).

When using the amorphous polyester polyol (a4), the amount used is based on 100 parts by mass of the ether polyol (a1), from the viewpoint of obtaining even better waterproofness, flexibility, and adhesiveness. The range is preferably from 10 to 500 parts by weight, more preferably from 15 to 400 parts by weight, even more preferably from 20 to 300 parts by weight.

Examples of the polyisocyanate (B) include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, Aliphatic or alicyclic polyisocyanates such as cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate can be used. Among these, aromatic polyisocyanates are preferred, and xylene diisocyanate is more preferred, since even better reactivity and adhesiveness can be obtained.

Note that when xylylene diisocyanate is used as the polyisocyanate (B), moisture curability and yellowing resistance are excellent, but adhesion to metals may be insufficient. In the present invention, it has been found that by using the metal organic compound (ii) described below in combination, adhesion to metals can be imparted without impairing moisture curability and yellowing resistance.

In addition, the amount of the polyisocyanate (B) to be used is preferably in the range of 5 to 60% by mass, and 10 to 30% by mass in the raw material of the urethane prepolymer (i), in order to obtain even better adhesiveness. The range is more preferable.

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

As a method for producing the urethane prepolymer (i), for example, the polyol (A) is dropped into a reaction vessel containing the polyisocyanate (B), and then heated, and the isocyanate groups of the polyisocyanate (B) are dissolved. can be produced by reacting under conditions in which the polyol (A) has an excess of hydroxyl groups relative to the hydroxyl groups possessed by the polyol (A).

The isocyanate group content (hereinafter abbreviated as "NCO%") of the urethane prepolymer (i) is 1 to 8%, since it provides even better waterproofness, adhesiveness, and flexibility. The range is preferably 1.3 to 6.5%, more preferably 1.6 to 5%. Note that the NCO% of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

The metal organic compound (ii) is an essential component for obtaining excellent adhesion to metal substrates. Examples of the metal organic compound (ii) include organic acid metal salts; other aluminum chelate compounds, aluminum alkoxide compounds, aluminum acylate compounds, titanium chelate compounds, titanium alkoxide compounds, titanium acylate compounds, and zirconium chelate compounds. , zirconium alkoxide compounds, zirconium acylate compounds, etc. can be used. These compounds may be used alone or in combination of two or more. Among these, organic acid metal salts and/or aluminum chelate compounds are preferably used because they have excellent compatibility with the urethane prepolymer (i) and provide even better adhesion to metal substrates. is preferred.

The organic acid metal salt is, for example, one in which a long-chain fatty acid and a metal ion are bonded, and one molecule contains a nonpolar or low polar part based on the fatty acid and a polar part based on the bonding part with the metal. You can use what you have along with it.

As the long-chain fatty acids, for example, saturated fatty acids having 1 to 18 carbon atoms, unsaturated fatty acids having 3 to 18 carbon atoms, aliphatic dicarboxylic acids, and the like can be used. Among these, saturated fatty acids having 1 to 18 carbon atoms are preferred because they have excellent compatibility with the urethane prepolymer (i) and provide even better adhesion to metal substrates; 6 to 18 saturated fatty acids are more preferred, and one or more fatty acids selected from the group consisting of 2-ethylhexanoic acid, neodecanoic acid, oleic acid, linoleic acid, and linolenic acid are preferred, and 2-ethylhexanoic acid, and /Or neodecanoic acid is more preferred.

As the metal ion, for example, lithium, sodium, potassium, magnesium, calcium, barium, neodymium, zinc, lead, cobalt, aluminum, manganese, bismuth, cerium, copper, zirconium, nickel, iron, etc. can be used. Among these, it is selected from the group consisting of zirconium, barium, bismuth, and neodymium because it has excellent compatibility with the urethane prepolymer (i) and provides even better adhesion to metal substrates. One or more metal ions are preferred.

Examples of the aluminum chelate compound include aluminum ethyl acetoacetate diisopropylate, aluminum tris(ethyl acetoacetate), aluminum alkyl acetoacetate diisopropylate, aluminum monoacetylacetonate bis(ethyl acetoacetate), and aluminum tris(acetylacetate). ), aluminum monoacetylacetate bis(ethylacetoacetate), aluminum di-n-butoxide monomethylacetoacetate, aluminum diisobutoxide monomethylacetoacetate, aluminum di-sec-butoxide monomethylacetoacetate, etc. can be used. These compounds may be used alone or in combination of two or more. Among these, bis[ethyl-3-(oxo-κO)butanoate-κO' has excellent compatibility with the urethane prepolymer (i) and provides even better adhesion to metal substrates. ](2-propanolato)aluminum and/or diisopropoxyaluminum ethyl acetoacetate are preferred.

The metal organic compound (ii) contains an organic solvent such as isopropyl alcohol, benzyl alcohol, n-hexane, diethylene glycol monobutyl ether, ethylbenzene, xylene, toluene, 2-ethylhexanoic acid, cyclohexane, etc., as necessary. Good too.

The content (solid content) of the metal organic compound (ii) is 0.00 parts by mass based on 100 parts by mass of the urethane prepolymer (i) from the viewpoint of obtaining even better adhesion to metal substrates. The range is preferably from 0.005 to 2 parts by weight, and more preferably from 0.01 to 1 part by weight.

The moisture-curable polyurethane hot melt resin composition of the present invention contains the urethane prepolymer (i) and the metal organic compound (ii) as essential components, but may contain other additives as necessary. Good too.

Examples of the other additives include antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, optical brighteners, silane coupling agents, and wax. These additives may be used alone or in combination of two or more.

A method for obtaining a cured film of the moisture-curable polyurethane hot-melt resin composition includes, for example, melting the moisture-curing polyurethane hot-melt resin composition at 50 to 130° C., then coating it on a substrate and moisture-curing it. There are several methods.

Examples of the base material include acrylic resin, urethane resin, silicone resin, epoxy resin, fluorine resin, polystyrene resin, polyester resin, polysulfone resin, polyarylate resin, polyvinyl chloride resin, Polyvinylidene chloride, cycloolefin resin, polyolefin resin, polyimide resin, alicyclic polyimide resin, cellulose resin, PC (polycarbonate), PBT (polybutylene terephthalate), modified PPE (polyphenylene ether), PEN (polyethylene) Resin films such as naphthalate), PET (polyethylene terephthalate), lactic acid polymer, ABS resin, and AS resin; Wooden base materials such as MDF, plywood, and particle board; Fiber base materials such as nonwoven fabrics, woven fabrics, and knitted fabrics; Stainless steel and aluminum Metal base materials such as copper, steel, chromium, zinc, duralumin, die casting, and alloys thereof can be used. The base material may be subjected to corona treatment, plasma treatment, primer treatment, etc., as necessary.

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

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

As described above, the moisture-curable polyurethane hot melt resin composition of the present invention has excellent adhesiveness to metal substrates. Therefore, the moisture-curable polyurethane hot melt resin composition of the present invention can be particularly suitably used as an adhesive used in assembling electronic materials.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1]
In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 16 parts by mass of polypropylene glycol (number average molecular weight: 1,000, hereinafter abbreviated as "PPG") and polyethylene were added. 20 parts by mass of polyoxypropylene glycol (number average molecular weight: 4,000, hereinafter abbreviated as "EOPO"), polyacrylic polyol (a reaction product of methyl methacrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate, several parts by mass) 16 parts by mass of crystalline polyester polyol (a reaction product of 1,6-hexanediol and adipic acid, number average molecular weight: 2,000, hereinafter referred to as "HG") 10 parts by mass of crystalline polyester polyol (reactant of 1,6-hexanediol and dodecanedioic acid, number average molecular weight: 3,500, hereinafter abbreviated as "HG/DDA"). ), amorphous polyester polyol (reactant of diethylene glycol, neopentyl glycol, 1,6-hexanediol, and adipic acid, number average molecular weight: 2,000, hereinafter abbreviated as "amorphous PEs"). ) and 0.1 part by mass of zirconium 2-ethylhexanoate were added, and the mixture was heated at 90°C to dehydrate until the water content became 0.05% by mass or less.
Next, after cooling the temperature inside the container to 60°C, 13 parts by mass of xylylene diisocyanate (hereinafter abbreviated as "XDI") was added, the temperature was raised to 110°C, and the temperature was kept at about 30°C until the isocyanate group content became constant. The mixture was reacted for a period of time to obtain a urethane prepolymer (i-1) having isocyanate groups, and a moisture-curable polyurethane hot melt resin composition was obtained. The NCO% of the urethane prepolymer (i-1) was 2.5% by mass.

[Example 2]
A moisture-curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1, except that barium 2-ethylhexanoate was used instead of zirconium 2-ethylhexanoate.

[Example 3]
A moisture-curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1, except that bismuth 2-ethylhexanoate was used instead of zirconium 2-ethylhexanoate.

[Example 4]
A moisture-curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1, except that neodymium neodecanoate was used instead of zirconium 2-ethylhexanoate.

[Example 5]
A moisture-curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1, except that the amount of neodymium neodecanoate used was changed from 0.1 part by mass to 0.5 part by mass.

[Example 6]
Example 1 except that aluminum chelate (bis[ethyl-3-(oxo-κO)butanoato-κO'](2-propanolato)aluminum) was used in place of zirconium 2-ethylhexanoate in Example 1. In the same manner as above, a moisture-curable polyurethane hot melt resin composition was obtained.

[Example 7]
A moisture-curable polyurethane hot melt resin composition was prepared in the same manner as in Example 1, except that aluminum chelate (diisopropoxyaluminum ethyl acetoacetate) was used instead of zirconium 2-ethylhexanoate. Obtained.

[Comparative example 1]
A moisture-curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1, except that the amount of zirconium 2-ethylhexanoate used was changed from 0.1 parts by mass to 0 parts by mass. .

[Method for measuring number average molecular weight]
In Examples and Comparative Examples, the number average molecular weights of polyols and the like are measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used by connecting them in series.
"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" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40℃
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (Tetrahydrofuran solution with sample concentration 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 of measuring adhesion]
The moisture-curable polyurethane hot melt resin 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 (PET) sheet using an applicator to a thickness of 100 μm. A metal plate (aluminum plate or SUS plate) was laminated onto the coating layer and pressed with a pressure roller. After that, after curing for 7 days at 23°C and 50% humidity, the adhesive strength (N/25mm) was measured using a precision universal testing machine "AG-10NX" manufactured by Shimadzu Corporation. Adhesion to materials was evaluated as follows.
"○": Adhesive strength is 25 (N/25 mm) or more.
"x": Adhesive strength is less than 25 (N/25 mm).

[Evaluation method of yellowing resistance]
The moisture-curable polyurethane hot melt resin compositions obtained in Examples and Comparative Examples were melted at 120° C. for 1 hour. The adhesive was applied onto release paper using an applicator to a thickness of 100 μm, and then cured for 7 days at 23° C. and 50% humidity. The obtained cured film was irradiated with light for 100 hours using a fade meter "U48AU" manufactured by Suga Test Instruments Co., Ltd. (63° C., humidity 50%). The color difference (ΔE) before and after light irradiation was measured and evaluated as follows.
"T": ΔE is less than 20.
"F": ΔE is 20 or more.

It has been found that the moisture-curable polyurethane hot melt resin composition of the present invention exhibits excellent adhesion to metal substrates. It has also been found that xylylene diisocyanate is excellent in yellowing resistance even when used as a raw material for the urethane prepolymer (i).

On the other hand, Comparative Example 1 did not contain the metal organic compound (ii), but had poor adhesion to metal substrates and poor yellowing resistance.

Claims (3)

Contains a urethane prepolymer (i) having an isocyanate group made from a polyol (A) and a polyisocyanate (B), and a metal organic compound (ii),
The polyol (A) contains a polyether polyol (a1), a polyacrylic polyol (a2), a crystalline polyester polyol (a3), and an amorphous polyester polyol (a4),
The polyisocyanate (B) is an aromatic polyisocyanate,
The metal organic compound (ii) is one or more selected from the group consisting of a combination of 2-ethylhexanoic acid and a metal ion, a combination of neodecanoic acid and a metal ion, and an aluminum chelate compound. A moisture-curable polyurethane hot melt resin composition. The moisture-curable polyurethane hot melt resin composition according to claim 1 , wherein the aromatic polyisocyanate is xylene diisocyanate. The moisture-curable polyurethane hot melt resin composition according to claim 1, wherein the isocyanate group content of the urethane prepolymer (i) is in the range of 1 to 8% by mass.