Moisture-curable reactive hot melt composition

Abstract

To provide a moisture-curable reactive hot-melt composition which is excellent in coating workability because of its moderate melt viscosity, has good adhesion to a transparent member, and suppresses the occurrence of a fogging phenomenon.SOLUTION: The moisture-curable reactive hot-melt composition comprises an isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B), and a polymeric silane coupling agent (Y) having a molecular weight of 450 or more and 3 or more organic functional groups.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a moisture-curable reactive hot melt composition (PUR). [Background technology]

[0002] Hot melt compositions have been the subject of extensive research and development. Hot melt compositions melt when heated and solidify when cooled to room temperature (approximately 23°C), making them ideal for use as adhesives. Their characteristics include being solvent-free, environmentally friendly, solidifying in a short time, and being extremely easy to handle. They are also widely used in a variety of fields because they can improve the working environment at manufacturing sites.

[0003] Hot melt compositions can be divided into moisture-curing and non-reactive types. Moisture-curing types mainly contain isocyanate-terminated urethane prepolymers, and in addition to solidifying upon cooling, they also react with moisture in the air to quickly cure. Non-reactive types mainly contain styrene-based thermoplastic elastomers or olefin-based elastomers, and do not undergo chemical reactions; they simply solidify upon cooling.

[0004] Previously, the applicant of the present application invented a moisture-curable 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 structural unit and a liquid polyester polyol (a2) having an aromatic dicarboxylic acid as a structural unit, the total of (a1) and (a2) being 50% by weight or more of the total polyol, with a polyfunctional isocyanate compound (B) (Patent Document 1). This invention 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]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-255187

[0006] PUR has traditionally been used favorably in the manufacturing process of automotive parts. Specifically, it can be used to bond the housing that constitutes an automotive lamp and the lens that covers the front of it. Furthermore, in recent years, its use has expanded to include in-vehicle parts, and as image display devices such as car-mounted displays (CIDs) tend to become larger, PUR, which is easy to handle, is often used in the manufacturing process.

[0007] Here, the PUR described in Patent Document 1 has somewhat low adhesiveness to the transparent members (glass substrates, polycarbonate resins, etc.) that constitute the display of an image display device, and further improvement has been required. Although PUR that solves this problem is generally available, there is a problem in that the transparent members sometimes become cloudy and lose transparency (fogging phenomenon). Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a moisture-curable reactive hot melt composition (PUR) that has an appropriate melt viscosity and therefore excellent application workability, has good adhesion to transparent materials, and suppresses the occurrence of fogging. [Means for solving the problem]

[0009] The present invention provides a moisture-curable reactive hot melt composition comprising an isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B), and a polymeric silane coupling agent (Y) having a molecular weight of 450 or more and having three or more organic functional groups. [Effects of the Invention]

[0010] The moisture-curable reactive hot melt composition (PUR) of the present invention has an appropriate melt viscosity, which makes it easy to apply, and it has the effect of having good adhesion to transparent materials and suppressing the occurrence of fogging. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Isocyanate-terminated urethane prepolymer> The present invention contains an isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B).

[0012] "Polyol compounds" In the present invention, a polyol compound (A) is used. Examples of the component (A) include polyester polyols (a1), polyether polyols (a2), polycarbonate polyols (a3), acrylic polyols (a4), and polybutadiene polyols (a5).

[0013] (polyester polyol) In the present invention, polyester polyol (a1) can be used. The component (a1) is a polyol compound having an ester skeleton, and can be divided into crystalline and non-crystalline types.

[0014] The component (a1) can be obtained by condensation polymerization of an alcohol having two or more hydroxyl groups and a carboxylic acid having two or more carboxyl groups.

[0015] Examples of alcohols having two or more hydroxyl groups include compounds having about 2 to 20 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.

[0016] Examples of carboxylic acids having two or more carboxyl groups include compounds 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.

[0017] In the present invention, it is preferable to use an aliphatic polyester polyol as the component (a1), and among these, it is particularly preferable to use a long-chain aliphatic polyester polyol. Examples of the long-chain aliphatic polyester polyol include polyester polyol (a1-1) represented by the following general formula (1):

[0018] [ka]

[0019] (In general formula (1), R 1 and R 2 each independently represents a linear alkylene group, and R 1 and R2 The total number of carbon atoms is 8 or more, and n is 3 to 40.

[0020] In addition, R 1 and R 2 The total number of carbon atoms in the copolymer is preferably 10 or more, more preferably 11 or more, even more preferably 12 or more, and particularly preferably 13 or more. The inventors of the present invention have found that the shear strength increases as the carbon chain length increases. It is speculated that one of the factors contributing to this effect is that the cohesive force increases due to the long carbon chain.

[0021] In the present invention, the polyester polyol (a1) preferably contains 40% by weight or more, more preferably 50% by weight or more, and particularly preferably 60% by weight or more of the polyester polyol (a1-1) represented by the above general formula (1).

[0022] An example of a commercially available product of the component (a1-1) is HS2H-200S (trade name, manufactured by Toyokuni Oil Mills, polyester polyol (hexanediol / sebacic acid), number average molecular weight: 2,000).

[0023] Furthermore, polyester polyols (a1-2) other than the component (a1-1) can be used as long as the effects of the present invention are not impaired.

[0024] An example of a commercially available product of the component (a1-2) is HS2H-451A (trade name, manufactured by Toyokuni Oil Mills, polyester polyol (hexanediol / adipic acid), number average molecular weight: 4,500).

[0025] (Polyether polyol) In the present invention, a polyether polyol (a2) can be used. The component (a2) is a polyol compound having an ether skeleton.

[0026] The component (a2) can be obtained by addition polymerization of the above-mentioned alcohols having two or more hydroxyl groups with ethylene oxide, propylene oxide, tetrahydrofuran, etc. Specific examples of the component (a2) include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0027] The number average molecular weight of the component (a2) is preferably 600 to 10,000, and particularly preferably 800 to 8,000.

[0028] Commercially available products of the component (a2) include PEG-1000 (trade name, manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (polyethylene glycol), number average molecular weight: 1,000) and Sannix PP-2000 (trade name, manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (polypropylene glycol), number average molecular weight: 2,000).

[0029] (Polycarbonate polyol) In the present invention, a polycarbonate polyol (a3) ​​can be used. The component (a3) ​​is a polyol having a carbonate structure as the skeleton.

[0030] The component (a3) ​​can generally be obtained by reacting an alcohol having two or more hydroxyl groups with a carbonate ester having two or more carbonate groups.

[0031] Examples of alcohols having two or more hydroxyl groups include the compounds mentioned above.

[0032] Examples of carbonate esters having two or more carbonate groups include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, and dicaprylyl carbonate.

[0033] The number average molecular weight of the component (a3) ​​is preferably 700 to 10,000, and particularly preferably 800 to 8,000.

[0034] Commercially available products of the component (a3) ​​include ETERNACOLL PH-200 (trade name, manufactured by UBE, number average molecular weight: 2,000).

[0035] (acrylic polyol) In the present invention, an acrylic polyol (a4) can be used. The component (a4) is an acrylic polymer having a terminal hydroxyl group.

[0036] The weight average molecular weight of the component (a4) is preferably 3,000 to 100,000, and particularly preferably 5,000 to 80,000.

[0037] Commercially available products of the component (a4) include ELVACITE 4402 (trade name, manufactured by Lucite Corporation, weight average molecular weight: 26,000).

[0038] (Polybutadiene polyol) In the present invention, polybutadiene polyol (a5) can be used. The component (a5) is a butadiene copolymer having terminal hydroxyl groups.

[0039] The number average molecular weight of the component (a5) is preferably 800 to 30,000, and particularly preferably 1,000 to 20,000.

[0040] An example of a commercially available product of the component (a5) is G-2000 (trade name, manufactured by Nippon Soda Co., Ltd., number average molecular weight: 1,900).

[0041] "Polyisocyanate compounds" In the present invention, an isocyanate compound (B) is used. The component (B) is preferably a polyfunctional isocyanate compound having two or more isocyanate groups at its terminals. Examples of the type of component (B) include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates.

[0042] Specific examples of component (B) include methylene diphenyl diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), and hydrogenated products thereof. Commercially available products of component (B) include Millionate MT (product name, manufactured by Tosoh Corporation, 4,4'-methylene diphenyl diisocyanate).

[0043] When the polyol compound (A) and the isocyanate compound (B) are reacted, the molar ratio of the hydroxyl groups of the polyol compound (A) to the isocyanate groups of the isocyanate compound (B) is preferably 1:1-5, more preferably 1:1.1-4, and particularly preferably 1:1.2-3.

[0044] When a plurality of polyol compounds (A) are used in the production of the isocyanate-terminated urethane prepolymer (X), it is preferable to thoroughly mix these and then add the isocyanate compound (B) to carry out the reaction.

[0045] <Polymer-type silane coupling agent> The present invention uses a polymeric silane coupling agent (Y) having a molecular weight of 450 or more and three or more organic functional groups. The inventors of the present invention discovered that the use of component (Y) can suppress the occurrence of fogging while maintaining shear strength, leading to the completion of the present invention. One of the factors that contribute to this effect is thought to be that component (Y) has a longer molecular chain and more crosslinking points than commonly used silane coupling agents.

[0046] The molecular weight of the component (Y) must be 450 or more, preferably 480 to 2,500, more preferably 500 to 1,800, and particularly preferably 520 to 1,500.

[0047] Specific examples of the component (Y) include polymeric silane coupling agents whose main chain has a siloxane structure, and which have, in addition to the siloxane main chain, multiple organic functional groups such as epoxy groups, acryloyl groups, and mercapto groups, and multiple alkoxy groups in their side chains.

[0048] Other examples include polymer-type silane coupling agents whose main chain has a structure other than a siloxane structure, such as those having a main chain other than a siloxane structure and having multiple organic functional groups such as epoxy groups, acryloyl groups, and mercapto groups, and multiple trialkoxysilyl groups, in their side chains.

[0049] The blending ratio of the (Y) component is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 20 parts by weight, and particularly preferably 0.05 to 10 parts by weight, per 100 parts by weight of the (X) component.

[0050] Commercially available products of the component (Y) include CoatOSil MP200 (trade name, manufactured by Momentive, main chain: siloxane structure, organic functional group: epoxy group, organic functional groups: 3 to 6, molecular weight: 600 to 1170).

[0051] In addition, the present invention can use a non-reactive acrylic polymer that does not have a functional group such as a hydroxyl group at the molecular chain end. Examples of such components include alkyl (meth)acrylate polymers. These components generally have a low Tg and are viscous at the PUR usage temperature, which allows them to impart adhesiveness.

[0052] In the present invention, fillers such as calcium carbonate, talc, and clay, and various additives such as antioxidants, preservatives, moisture absorbents, colorants, and antifoaming agents may also be contained.

[0053] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these descriptions. [Example]

[0054] <Examples and Comparative Examples> In the formulation shown in Table 1, polyol compound (A) and defoaming agent were placed in a separable flask equipped with a stirrer, temperature controller, and vacuum pump. After stirring and dehydrating for 2 hours at 120°C under reduced pressure, a predetermined amount of isocyanate compound (B) was added, and the mixture was stirred and reacted for 1.5 hours at 100°C under a nitrogen atmosphere to obtain an isocyanate-terminated urethane prepolymer (X). A catalyst and, optionally, a silane coupling agent were then added, and the mixture was stirred and mixed for 30 minutes to obtain a moisture-curable reactive hot melt composition (PUR) according to the present invention. The amount of isocyanate compound (B) was adjusted so that the molar ratio of the hydroxyl groups of the polyol compound to the isocyanate groups of the polyisocyanate compound was 1:1.9. The values ​​in Table 1 represent parts by weight. The raw materials used are listed below. HS2H-451A (trade name, Toyokuni Oil Mills, polyester polyol (hexanediol / adipic acid), number average molecular weight: 4,500) HS2H-200S (trade name, Toyokuni Oil Mills, polyester polyol (hexanediol / sebacic acid), number average molecular weight: 2,000) Sannix PP-2000 (product name, manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (polypropylene glycol), number average molecular weight: 2,000) E-4402 (trade name, Mitsubishi Chemical Corporation, acrylic polyol) E-2903 (trade name, Mitsubishi Chemical Corporation, acrylic polyol) MODAFLOW (product name, antifoaming agent, manufactured by Allnex) DMDEE (Mitsui Fine Chemicals, catalyst) CoatOSil MP200 (trade name, manufactured by Momentive, main chain: siloxane structure, organic functional group: epoxy group, organic functional group: 3 to 6, molecular weight: 600 to 1170) Millionate MT (product name, manufactured by Tosoh Corporation, 4,4'-methylenediphenyl diisocyanate)

[0055] [Table 1]

[0056] The PUR obtained in the above examples was evaluated for the following physical properties. The results are shown in Table 2.

[0057] <Melt viscosity> The PUR was heated to 120°C and melted, and then rotation was started using a Brookfield viscometer at a measurement temperature of 120°C, spindle No. 29, and rotation speed of 10 rpm. The melt viscosity (mPa·s) was measured after 15 minutes.

[0058] <Adhesion strength> After heating the PUR to 120°C to melt it, it was applied to a polycarbonate resin (PC) or glass substrate, and immediately laminated to another glass substrate. After that, the test specimen was cured for one day under conditions of 23°C temperature and 50% humidity. At the time of lamination, the thickness of the PUR was 100 μm, and the adhesive area was 125 mm 2 (5 mm x 25 mm). A shear test was then carried out using an autograph (manufactured by Shimadzu Corporation) at a tensile speed of 50 mm / min to measure the adhesive strength (MPa).

[0059] <Fogging test> 10 g of cured PUR was placed in a flask, the flask opening was covered with a transparent polycarbonate resin (PC), and the flask was heated in a mantle heater at 120°C for 24 hours, after which it was cooled to room temperature. The transparency of the PC was then visually confirmed. The transparency of the lid was evaluated as ◯ if the lid's transparency remained unchanged, △ if only part of the lid was not transparent, and × if the entire lid was not transparent.

[0060] [Table 2]

[0061] When the PURs according to the examples and comparative examples were manufactured, the melt viscosities at 120°C were similar, but the examples had better adhesion to transparent materials than the comparative examples, and the occurrence of fogging was suppressed.

Claims

1. an isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B); A moisture-curable reactive hot melt composition comprising: a polymeric silane coupling agent (Y) having a molecular weight of 450 or more and having 3 or more organic functional groups;

2. 2. The moisture-curable reactive hot melt composition according to claim 1, wherein the main chain of the polymeric silane coupling agent (Y) has a siloxane structure.

3. 2. The moisture-curable reactive hot melt composition according to claim 1, wherein the organic functional group of the polymeric silane coupling agent (Y) is an epoxy group.

4. The polyol compound (A) contains a polyester polyol (a1), The moisture-curable reactive hot melt composition according to claim 1, characterized in that the polyester polyol (a1) contains a polyester polyol (a1-1) represented by the following general formula (1): 【Chemistry 1】 (In general formula (1), R １ and R ２ each independently represents a linear alkylene group, R １ and R ２ The total number of carbon atoms is 13 or more, and n is 3 to 40.

5. A cured product comprising the moisture-curable reactive hot melt composition according to any one of claims 1 to 4.

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