JP4308690B2 - One-component moisture-curable urethane composition that can be easily thermally decomposed - Google Patents

Description

  In applications such as adhesives, sealing materials, paints, sealants, casting materials, foams, molded products, etc., the present invention is easily thermally decomposed by heat treatment when it is desired to remove the members by peeling or disassembling the members. One-component moisture-curable urethane composition, more specifically, one-component moisture that can be easily thermally decomposed using a terminal isocyanate group-containing urethane prepolymer containing a urethane bond by reaction of an oxime group and an isocyanate group as a component Regarding curable urethane-based compositions, for example, when used as an adhesive for application to automobile window glass, it is easily softened and decomposed by heat treatment as desired after moisture curing, thereby easily removing the window glass from the vehicle body. The present invention relates to a one-component moisture-curable urethane composition that can be used.

Background art and problems to be solved by the invention

  For example, at present, automotive window glass is generally bonded to a terminal isocyanate group-containing urethane prepolymer, which is obtained by a reaction between a polyol and an excess amount of a polyisocyanate compound, and has a urethane bond by a reaction between a hydroxyl group and an isocyanate group. In general, a one-component moisture-curable urethane composition containing a plasticizer, a filler, a curing catalyst, and the like is used. However, automotive window glass adhesives are required to have high strength and high durability due to the structure of the automobile. On the other hand, there is a need to dismantle automobiles and dismantle them when replacing window glass. When it occurs, the cured adhesive must be broken and cut, or peeled off by thermal decomposition. However, since the adhesive has strong rubber elasticity, it is difficult to cut it with a piano wire or a cutter. Further, when heat decomposition is performed, heat treatment at a very high temperature is necessary, which may cause an increase in equipment load, an increase in utility costs, generation of cyan gas, and the like. For this reason, when the automobile is disassembled, it is required that the automobile can be easily peeled and disassembled at a lower heating temperature.

  Under such circumstances, a urethane bond by the reaction of a phenolic hydroxyl group and an isocyanate group is already introduced into the terminal isocyanate group-containing urethane prepolymer of the main component, that is, the polyol component has a phenolic hydroxyl group. By adding compounds such as hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, bis (4-hydroxyphenyl) sulfide, etc., and reacting them with an excess amount of polyisocyanate compound, the heating is lower than before the introduction. A technique that can be easily peeled off at a temperature has been proposed (for example, see Patent Document 1).

JP 2002-308958 A (2-6 pages)

  The inventors of the present invention have made extensive studies to satisfy the demand for exfoliation at a relatively low heat treatment temperature, and have a terminal isocyanate group containing a urethane bond by a reaction between an oxime group and an isocyanate group. The use of a urethane prepolymer has led to the completion of the present invention by finding that a decomposition effect by low heating that is not inferior to the proposed technique can be obtained.

  That is, the present invention comprises a terminal isocyanate group-containing urethane prepolymer [hereinafter referred to as a terminal NCO-containing prepolymer (A)] containing a urethane bond by the reaction of an oxime group and an isocyanate group (hereinafter referred to as NCO) as a component. It is an object of the present invention to provide a one-component moisture-curable urethane composition that can be easily thermally decomposed.

  According to the present invention, when the front and rear window glass of an automobile is applied to an adhesive that adheres to a vehicle body, the normal adhesiveness that is originally required is not affected at all, and the adhesive can be quickly produced by low heating as a heat treatment. It is recognized that the adhesive interface breaks and can be easily peeled off, which can improve the efficiency when dismantling the automobile and reuse the glass, which can be recycled and reduce industrial waste. Also contributes.

  The terminal NCO-containing prepolymer (A) used in the present invention contains an isocyanate group-containing polyisocyanate compound in excess of the oxime group-containing compound (usually OH of the oxime compound / NCO of the polyisocyanate compound = 1 / 1.5). ˜1 / 4.0) is produced by a conventional reaction.

The oxime group-containing compound is preferably a dioxime compound, such as dimethylglyoxime, furyl dioxime, p-benzoquinone dioxime, p, p-dibenzoylbenzoquinone dioxime, a formula:
HON = CH-R-CH = NOH
(Wherein R is a _C5-10 aliphatic or alicyclic hydrocarbon group)
For example, 1,7-heptane diar dioxime, 1,8-octane diar dioxime, 2-methyl-1,8-octane diar dioxime, 1,9-nonane diar dioxime 1,10-decandial dioxime, 1,11-undecandial dioxime, 1,12-dodecanedial dioxime, 3,8-dimethyl-1,10-decandial dioxime, 3,7 -Dimethyl-1,10-decandial dioxime, cyclohexane-1,3 (4) -dicarbaldehyde dioxime, bicyclo [2.2.1] heptane-2 (3), 5 (6) -dicarba Rudehydrodioxime, bicyclo [2.2.2] octane-2 (3), 5 (6) -dicarbaldehyde dioxime, tricyclo [5.2.1.0] decane-3 (4), 8 (9 -Dikarbar Dehydrodioxime etc. are mentioned.

  Examples of the polyisocyanate compound include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), lysine diisocyanate, isopropylene. Examples include redenebis (4-cyclohexyl isocyanate) and hydrogenated XDI.

  The terminal NCO-containing prepolymer (A) and a terminal NCO-containing urethane prepolymer produced by reacting an excess amount of a polyisocyanate compound with a commonly used polyol (hereinafter referred to as a terminal NCO-containing prepolymer (B)) May be used in combination.

Examples of the polyol include polyether polyols such as polyoxyalkylene polyol (referred to as PPG), modified polyether polyol, and polytetramethylene ether glycol; polyester polyols such as condensed polyester polyol, lactone polyester polyol, and polycarbonate diol; A polyol having a main chain composed of a C—C bond, such as an acrylic polyol, a polybutadiene-based polyol, a polyolefin-based polyol, a saponified ethylene-vinyl acetate copolymer; other flame retardant polyols, phosphorus-containing polyols, halogen-containing polyols, etc. It is done.

In this case, the terminal NCO-containing prepolymer (B) is selected and used at a ratio of 0 to 900 parts by weight with respect to 100 parts by weight of the terminal NCO-containing prepolymer (A). Usually, when the terminal NCO group-containing prepolymer (A) is moisture-cured, a cured product having a hard physical property tends to be obtained. Adhesives, paints, casting agents, foams, and molded products designed to be a hard cured product are used. If you want to get it, increase the usage rate. In the case of a sealing material or adhesive that requires rubber elasticity, it is desirable to mix and use the terminal NCO group-containing prepolymer (B). A terminal NCO group-containing urethane prepolymer (A) and a terminal NCO group-containing prepolymer (B) are prepared according to desired physical properties to be moisture-cured.

  In the above, it has been described that the terminal NCO group-containing prepolymer (A) and the terminal NCO group-containing prepolymer (B) are prepared separately and then mixed in a desired ratio. However, the terminal NCO group-containing prepolymer (A) Needless to say, the terminal NCO group-containing prepolymer (B) may be optionally prepared at the same time. For example, when preparing a terminal NCO group-containing prepolymer (A) by reacting an oxime group-containing compound and an isocyanate group-containing compound to prepare a terminal NCO group-containing prepolymer (B) or a polyol and an isocyanate group-containing compound. It can also be obtained by mixing the polyol used in preparing the NCO group-containing urethane prepolymer (B) and the oxime group-containing compound, or adding them sequentially to react with the isocyanate group-containing compound. Further, in the production of the terminal NCO group-containing urethane prepolymer (A) or (B), a terminal NCO group-containing reaction product obtained by reacting with a polyol and an isocyanate group-containing compound in advance is obtained, and then the oxime group-containing compound is reacted. It is also possible to obtain a terminal NCO group-containing urethane prepolymer, but conversely, a terminal NCO group-containing reaction product obtained by reacting an oxime group-containing compound and an isocyanate group-containing compound in advance is reacted with a polyol to form a terminal NCO group. Containing prepolymer (A) or (B) may be prepared. Thus, in the terminal NCO group-containing prepolymer (A) or (B), the urethane bond (hereinafter referred to as oxime urethane bond) reacted with the oxime group and the isocyanate group in the molecule, and the urethane reacted with the polyol group and the isocyanate group. It only needs to contain a bond and may exist in separate molecules.

  By introducing a urethane bond by the reaction of the oxime group and NCO, the intended low-temperature exfoliation can be obtained, but in order to further improve, an appropriate amount of a heat-expandable balloon may be added. Here, the thermally expandable balloon is a thermal expansion material such as liquid gas or low boiling point hydrocarbon such as polyvinylidene chloride, polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-methyl methacrylate copolymer, etc. A plastic sphere encapsulated in a plastic shell is designated.

As described above, the one-component moisture-curable urethane composition containing the terminal NCO group-containing prepolymer (A) as a component can soften and decompose oxime urethane bonds under heat treatment conditions at a relatively low temperature. it can. Therefore, when the one-component moisture-curable urethane-based composition of the present invention that can be easily thermally decomposed is used for applications such as adhesives, sealing materials, paints, casting materials, sealing materials, foams, molded products, etc., peeling If heat treatment is performed when necessary for dismantling, etc., it can be easily softened and decomposed under relatively low temperature heat treatment conditions. As a result, it is possible to recycle parts and reduce waste, and industrial waste can be reduced in volume when it is discarded, thus protecting the global environment and reducing the burden on the global environment. .

  The one-component moisture-curable urethane-based composition that can be easily thermally decomposed according to the present invention comprises the above-mentioned terminal NCO-containing prepolymer (A) as a component (if necessary, the terminal NCO-containing prepolymer (B) And a heat-expandable balloon), and generally a system containing a plasticizer, a filler, and a curing catalyst. Here, the content of the terminal NCO-containing prepolymer (A) (main component) may be usually selected in the range of 20 to 60% in the total amount of the composition.

Examples of the plasticizer include diisononyl phthalate (DINP), dioctyl phthalate (DOP), dibutyl phthalate, dilauryl phthalate, butyl benzyl phthalate, dioctyl adipate, diisodecyl adipate, trioctyl phosphate, tris (chloroethyl) phosphate, tris (dichloropropyl). ) Phosphate, propylene glycol adipate polyester, butylene glycol adipate polyester, epoxy alkyl stearate, alkylbenzene, epoxidized soybean oil, etc. are included, and the blending amount is usually selected in the range of 0 to 50% in the total amount of the composition Good.
Examples of the filler include calcium carbonate, silica, carbon black, clay, talc, titanium oxide, quicklime, kaolin, zeolite, diatomaceous earth, and the blending amount is usually in the range of 0 to 50% in the total amount of the composition. May be selected.

  Examples of the curing catalyst include organic tin compounds (dibutyltin diacetylacetonate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin maleate, dioctyltin maleate, tin octylate, etc.); 2,2′-dimorpholinodiethyl ether, (2,6-dimethylmorpholinoethyl) ether; bismuth carboxylate (bismuth 2-ethylhexanoate, bismuth octylate, bismuth neodecanoate, etc.); carboxylic acid (benzoic acid, phthalic acid, 2-ethylhexanoic acid, octylic acid, Stearic acid, oleic acid, linoleic acid, etc.), and the blending amount may usually be selected in the range of 0.0001 to 5% of the total composition.

  Further, if necessary, an adhesive [modified polyisocyanate compound having a molecular weight of less than 1000 (for example, a hexamethylene diisocyanate modified buret, isocyanurate modified, trimethylolpropane modified, etc.); containing the polyisocyanate compound and an alkoxysilyl group Compound (mercaptopropyltrimethoxysilane, mercaptopropylmethyldimethoxysilane, γ-N-phenylaminopropyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane, etc .; further alkoxysilyl group-containing polyurethane polymer, alkoxysilyl group-containing polyether Polymer, alkoxysilyl group-containing vinyl polymer, alkoxysilyl group-containing polyester polymer, alkoxysilyl group-containing diene polymer, alkoxy A reaction product of a silyl group-containing polyalkylene polymer, and the like, and one or more selected from the alkoxysilyl group-containing compound, and the blending amount is usually in the range of 0.1 to 10% in the total amount of the composition. In addition, an appropriate amount of a solvent (xylene, toluene, etc.); an anti-aging agent, an antioxidant, an ultraviolet absorber, a hygroscopic water-absorbing agent, a pigment, etc. may be added.

Next, the present invention will be described more specifically with reference to production examples, examples and comparative examples.
Production Example 1: Production of terminal NCO-containing prepolymer (A) To 20 g of dimethylglyoxime, 1035 g of a polyoxypropylene diol having a hydroxyl value of 27.9 and 203 g of a polyoxypropylene triol having a hydroxyl value of 33.7 were added, and a nitrogen atmosphere was added. Stir at 90 ° C. for 2 hours, then add 258 g of 4,4′-diphenylmethane diisocyanate (MDI) and 0.3 g of tin octylate diluted to 1% with diisononyl phthalate (DINP) at 80 ° C. in a nitrogen atmosphere. The reaction is performed for 6 hours to obtain a terminal NCO-containing prepolymer (A) having an oxime urethane bond (35) mol% in all urethane bonds, a free NCO group content of 2.95%, and a viscosity of 200,000 mPa · S (20 ° C.).

Production Example 2: Production of terminal NCO-containing prepolymer (B) 1035 g of polyoxypropylene diol having a hydroxyl value of 27.9 and 203 g of polyoxypropylene triol having a hydroxyl value of 33.7, 167 g of MDI, and octyl diluted to 1% with DINP 0.3 g of tin oxide was added and reacted at 80 ° C. for 3 hours under a nitrogen atmosphere to obtain a terminal NCO-containing prepolymer (B) having a free NCO group content of 2.10% and a viscosity of 50000 mPa · S (20 ° C.). obtain.

Production Example 3:
85.2 g of MDI is added to 50 g of diarylbisphenol A and 135 g of DINP and reacted for 4 hours under a nitrogen atmosphere to obtain a urethane prepolymer having a free NCO group content of 5.44%.

Example 1
400 parts (parts by weight, the same applies hereinafter) of the terminal NCO-containing prepolymer (A) of Production Example 1 were added to 200 parts of DINP, 200 parts of dried carbon black, 150 parts of calcium carbonate, a thermally expandable balloon (manufactured by Nippon Philite Co., Ltd. EXPANSEL 009DU80 ") 2 parts, 1 part of 2,2-dimorpholinodiethyl ether and 0.2 part of bismuth octylate were added and stirred and mixed under reduced pressure defoaming. One-part moisture curing with a viscosity of 75 Pa · s A functional urethane-based composition is obtained.

Comparative Example 1
To 350 parts of the terminal NCO-containing prepolymer (B) of Production Example 2, 200 parts of DINP, 200 parts of dried carbon black, 200 parts of calcium carbonate, 1 part of 2,2-dimorpholinodiethyl ether and 0.2 part of bismuth octylate are added. In addition, the mixture is stirred and mixed under reduced pressure defoaming to obtain a one-pack type moisture-curable urethane composition having a viscosity of 60 Pa · s.

Comparative Example 2
In Example 1, instead of the terminal NCO-containing prepolymer (A) (400 parts) of Production Example 1, the terminal NCO-containing prepolymer (B) of Production Example 2 (375 parts) and the urethane prepolymer of Production Example 3 ( A one-component moisture-curable urethane composition is obtained in the same manner except that 25 parts) is used.

Adhesion interface in the case of preparing a shear test piece in the following manner for the one-component moisture-curable urethane-based composition of Adhesion Test Example 1 and Comparative Examples 1-2, and then heating with a high-frequency induction heating device Measure the time to break and the temperature at break. The results are shown in Table 1 below.
A primer (Sunstar Giken Co., Ltd., # 435-41) is applied as a pretreatment for adhesion to a 25 mm wide glass plate and dried.
On the other hand, a primer (Sunstar Giken Co., Ltd., # 435-98) was applied to a 25 mm wide coated steel sheet coated with an automotive baking paint, dried, and then dried. A one-component moisture-curable urethane-based composition is applied and corrected so as to have an adhesion width of 25 mm, a thickness of 5 mm, and a depth of 10 mm, and then the pretreated glass plate is overlaid to prepare a shear test piece.

Such a shear test piece is allowed to stand at 20 ° C. and 65% RH for 168 hours, and at this point, the normal tensile strength (MPa) is measured (tensile strength 50 mm / min).
Moreover, the dismantling property of the shear test piece produced similarly is confirmed. That is, the coated steel plate part of the shear test piece is fixed so that the coated steel plate side is at a distance of 4 mm from the irradiated surface of the high frequency induction heating device (Achilles Co., Ltd., all-over bonding device). The time until the adhesive interface naturally breaks and the temperature of the coated steel sheet near the adhesive at the time of the breakage are measured.

The one-component moisture-curable urethane-based composition that can be easily thermally decomposed according to the present invention is particularly useful as an adhesive used for bonding automobile window glass, but other adhesives, sealing materials, paints, casting materials, Needless to say, the present invention can also be applied to a sealing material, a foam, a molded body, etc. that can be easily decomposed by heat treatment when removing the member, such as when repairing, recycling, or discarding the member.
Preferred embodiments of the present invention include the following.
[1] A readily heat-decomposable one-component moisture-curable urethane-based composition comprising, as a component, a terminal isocyanate group-containing urethane prepolymer containing a urethane bond by a reaction between an oxime group and an isocyanate group.
[2] The easily heat-decomposable one-component moisture-curable urethane composition according to [1], wherein the oxime group-containing compound is a dioxime compound and the isocyanate group-containing compound is a polyisocyanate compound.
[3] Easy thermal decomposition as described in [1] or [2] used for adhesives, sealing materials, paints, casting materials, sealing materials, foams that need to be easily softened and disassembled by heat treatment One-pack type moisture curable urethane composition that can be used.
[4] The one-component moisture-curable urethane-based composition that can be easily thermally decomposed according to any one of [1] to [3], which is an adhesive used for bonding an automobile window glass.

Claims (3)

An easily heat-decomposable one comprising a terminal isocyanate group-containing urethane prepolymer containing a urethane bond by a reaction between an oxime group of a compound containing an oxime group and an isocyanate group of a compound containing an isocyanate group. A liquid moisture curable urethane composition, wherein the compound containing the oxime group is a dioxime compound, and the compound containing the isocyanate group is a polyisocyanate compound.   The one-component moisture curing which can be easily thermally decomposed according to claim 1, which is used for adhesives, sealing materials, paints, casting materials, sealing materials and foams which need to be easily softened and disassembled by heat treatment. Urethane-based composition.   The one-component moisture-curable urethane-based composition according to claim 1 or 2, which is an adhesive used for adhering automobile window glass.