Moisture-curable reactive hot-melt composition

Abstract

To provide a moisture-curable reactive hot-melt composition that features superior coating workability due to moderate melt viscosity, offers superior adhesion to transparent members, and prevents the occurrence of fogging phenomenon.SOLUTION: A moisture-curable reactive hot-melt composition contains: an isocyanate-terminated urethane prepolymer (X) derived from the reaction between a polyol compound (A) and an isocyanate compound (B); and an epoxy silane coupling agent (Y) with a molecular weight of 400 or more.SELECTED DRAWING: None

Description

[Technical field]

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

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

[0005] PUR has been used suitably in the manufacturing process of automobile parts. A specific example is bonding a housing part constituting an automobile lamp and a lens part covering the front of the housing part. Furthermore, in recent years, image display devices such as car-mounted displays (CIDs) have tended to become larger, and PUR, which is easy to handle, is sometimes used in the manufacturing process.

[0006] Here, the PUR described in Patent Document 1 has a rather low adhesiveness to transparent members (glass substrates, polycarbonate resins, etc.) that constitute the display of an image display device, and therefore further improvement has been desired.

[0007] Although PUR that solves the above problems is generally available, there is still a problem in that transparent components can become cloudy and white, reducing transparency (fogging). 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 coating workability, has good adhesion to transparent materials, and suppresses the occurrence of fogging. [Means for solving the problem]

[0009] The present invention relates to a moisture-curable reactive hot melt composition (PUR) characterized by containing an isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B), and an epoxy-based silane coupling agent (Y) having a molecular weight of 400 or more. Effect 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 has the effect of suppressing the occurrence of fogging, as well as providing good adhesion to transparent materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 compound" In the present invention, a polyol compound (A) is used. Examples of the type of component (A) include polyester polyol (a1), polyether polyol (a2), polycarbonate polyol (a3), acrylic polyol (a4), and polybutadiene polyol (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 ones.

[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 a carbon number of about 2 to 20, 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. Among these, it is particularly preferable to use at least one alcohol selected from the group consisting of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,9-nonanediol.

[0016] Examples of carboxylic acids having two or more carboxyl groups include compounds having a carbon number of about 2 to 24, 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. Among these, it is particularly preferable to use at least one carboxylic acid selected from the group consisting of adipic acid, sebacic acid, terephthalic acid, and dodecanedicarboxylic acid.

[0017] The number average molecular weight of the component (a1) is preferably from 600 to 20,000, and particularly preferably from 800 to 10,000.

[0018] Commercially available products of the component (a1) include HS2H-200S (trade name, manufactured by Toyokuni Oil Mills, polyester polyol (hexanediol / sebacic acid), number average molecular weight: 2,000) and HS2H-451A (trade name, manufactured by Toyokuni Oil Mills, polyester polyol (hexanediol / adipic acid), number average molecular weight: 4,500).

[0019] (Polyether polyol) In the present invention, a polyether polyol (a2) can be used. The (a2) component is a polyol compound having an ether skeleton.

[0020] The (a2) component 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 (a2) component include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

[0021] The number average molecular weight of the component (a2) is preferably from 600 to 10,000, and particularly preferably from 800 to 8,000.

[0022] 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).

[0023] (Polycarbonate polyol) In the present invention, a polycarbonate polyol (a3) ​​can be used. The component (a3) ​​is a polyol having a carbonate structure as a skeleton.

[0024] 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.

[0025] Examples of the alcohols having two or more hydroxyl groups include the compounds mentioned above.

[0026] Examples of carbonate esters having two or more carbonate groups include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, and dicaprylyl carbonate.

[0027] The number average molecular weight of the component (a3) ​​is preferably from 700 to 10,000, and particularly preferably from 800 to 8,000.

[0028] An example of a commercially available product of the component (a3) ​​is ETERNACOLL PH-200 (product name, manufactured by UBE, number average molecular weight: 2,000).

[0029] (Acrylic polyol) In the present invention, an acrylic polyol (a4) can be used. The component (a4) is an acrylic polymer having a hydroxyl group at its terminal.

[0030] The weight average molecular weight of the (a4) component is preferably from 3,000 to 100,000, and particularly preferably from 5,000 to 80,000.

[0031] An example of a commercially available product of the component (a4) is ELVACITE 4402 (trade name, manufactured by Lucite Corporation, weight average molecular weight: 26,000).

[0032] (Polybutadiene polyol) In the present invention, polybutadiene polyol (a5) can be used. The (a5) component is a butadiene-based copolymer having a hydroxyl group at its terminal.

[0033] The number average molecular weight of the component (a5) is preferably from 800 to 30,000, and particularly preferably from 1,000 to 20,000.

[0034] An example of a commercially available product of the component (a5) is G-2000 (product name, manufactured by Nippon Soda Co., Ltd., number average molecular weight: 1,900).

[0035] "Polyisocyanate compounds" In the present invention, an isocyanate compound (B) is used. The (B) component is preferably a polyfunctional isocyanate compound having two or more isocyanate groups at its terminal. The types of the (B) component include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates.

[0036] Specific examples of the 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 the component (B) include Millionate MT (product name, manufactured by Tosoh Corporation, 4,4'-methylene diphenyl diisocyanate).

[0037] 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.

[0038] In the production of the isocyanate-terminated urethane prepolymer (X), when a plurality of polyol compounds (A) are used, it is preferable to thoroughly mix these and then add the isocyanate compound (B) to react them.

[0039] <Silane coupling agent> In the present invention, an epoxy-based silane coupling agent (Y) having a molecular weight of 400 or more is used. The inventors of the present invention found that the problem of the present invention can be solved by using the (Y) component, and completed the present invention. One of the factors that produces such an effect is thought to be due to the fact that the (Y) component has a longer molecular chain and more crosslinking points than commonly used silane coupling agents.

[0040] The molecular weight of the (Y) component must be 400 or more, and is preferably 420 to 2,500, more preferably 450 to 2,000, even more preferably 480 to 1,800, and particularly preferably 500 to 1,500.

[0041] 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.

[0042] An example of a commercially available product of the component (Y) is CoatOSil MP200 (product name, manufactured by Momentive Corporation, molecular weight: 600 to 1170).

[0043] In addition, in the present invention, a non-reactive acrylic polymer that does not have a functional group such as a hydroxyl group at the molecular chain end can be used. Examples of such components include polymers of alkyl (meth)acrylate. Such components generally have a low Tg and are viscous at the use temperature of PUR, so that they can impart adhesion.

[0044] In the present invention, various additives such as fillers, such as calcium carbonate, talc, and clay, antioxidants, preservatives, moisture absorbents, colorants, and antifoaming agents may be contained.

[0045] 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. EXAMPLES

[0046] <Examples and Comparative Examples> In the formulation shown in Table 1, the polyol compound (A) and the defoaming agent were put into a separable flask equipped with a stirrer, a temperature controller, and a vacuum pump, and after stirring and dehydrating for 2 hours at 120°C under reduced pressure, a predetermined amount of the isocyanate compound (B) was added, and the mixture was stirred and reacted for 1.5 hours under a nitrogen atmosphere at 100°C to obtain an isocyanate-terminated urethane prepolymer (X). Then, a catalyst and optionally various silane coupling agents were 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 the isocyanate compound (B) was such that the molar ratio of the hydroxyl group of the polyol compound to the isocyanate group of the polyisocyanate compound was 1:1.9. Here, the numerical values ​​in Table 1 represent parts by weight. The raw materials used are shown below. HS2H-451A (product name, Toyokuni Oil Co., Ltd., polyester polyol (hexanediol / adipic acid), number average molecular weight: 4,500) HS2H-200S (product name, Toyokuni Oil Co., Ltd., 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 (product name, Mitsubishi Chemical Corporation, acrylic polyol) E-2903 (product name, Mitsubishi Chemical Corporation, acrylic polyol) MODAFLOW (product name, Allnex, defoamer) Millionate MT (product name, Tosoh Corporation, 4,4'-methylenediphenyl diisocyanate) DMDEE (Mitsui Fine Chemicals, catalyst) CoatOSil MP200 (product name, manufactured by Momentive, epoxy-based silane coupling agent, molecular weight: 600-1170) KBE403 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., epoxy-based silane coupling agent (3-glycidoxypropyltriethoxysilane), molecular weight: 278)

[0047] [Table 1]

[0048] The PUR obtained in the above examples was subjected to the following physical property evaluations. The results are shown in Table 2.

[0049] <Melt viscosity> The PUR was heated to 120°C and melted, and then rotation was started at 120°C, spindle No. 29, and rotation speed of 10 rpm using a Brookfield viscometer. The melt viscosity (mPa·s) was measured after 15 minutes.

[0050] <Adhesive strength> After heating the PUR to 120°C to melt it, it was applied to polycarbonate resin and immediately laminated to a glass substrate. The specimen was then cured for one week under conditions of temperature 23°C and humidity: 50% to prepare a test specimen. Note that when laminating, the thickness of the PUR was 100 μm and the adhesive area was 125 mm 2 (5 mm × 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).

[0051] <Fogging test> 10 g of the cured PUR was placed in a flask, the flask opening was covered with a transparent polycarbonate resin, and the flask was heated at 120°C for 24 hours using a mantle heater, and then cooled to room temperature. The transparency of the covered polycarbonate resin was then measured using a haze meter (manufactured by Toyo Seiki Seisakusho, product name: HAZE GARD 2). Note that a higher haze value indicates a lower transparency.

[0052] [Table 2]

[0053] When the PURs according to the examples and comparative examples were manufactured, the melt viscosities at 120°C were approximately the same, but the examples had better adhesion to transparent materials and suppressed the occurrence of fogging compared to the comparative examples.

Claims

1. An isocyanate-terminated urethane prepolymer (X) obtained by reacting a polyol compound (A) with an isocyanate compound (B); and an epoxy-based silane coupling agent (Y) having a molecular weight of 400 or more.

2. 2. The moisture-curable reactive hot melt composition according to claim 1, which is used in the manufacture of an image display device.

3. 2. An image display device manufactured by using the moisture-curable reactive hot melt composition according to claim 1.

Images