JP7576989B2 - Urethane resin composition - Google Patents

Description

The present invention relates to a urethane resin composition that bonds civil engineering and architectural structures, such as roads, buildings, dams, and embankments, which are made up of multiple materials and components, and mechanical structures, such as automobiles, motorcycles, trains, diesel railcars, ships, and airplanes.

As mentioned above, various structures are made up of multiple materials and parts, and when using adhesive techniques, bonding dissimilar materials can be very difficult. Bonding structures requires high bonding reliability, whether the materials are dissimilar or homogeneous.
In particular, in the case of vehicles such as automobiles, the adhesive must have high adhesive strength, and the physical properties of a hardened adhesive must be such that it does not easily break when subjected to vibrations and the like, as well as a high maximum stress and high elongation.

Patent Document 1 is a publication about a urethane resin composition for golf balls. It was difficult to apply it to structural bonding.

JP2003-102871 JP2004-204139 Patent Publication 2009-091414 Patent Publication 2015-113369

Patent Document 2 is a publication about a sealant. Although it has the properties of a sealant, it was difficult to apply it to bonding structures.

Patent Document 3 is a publication about a urea resin composition that can be hand-applied, has good water resistance, and is suitable for use as a coating material to prevent peeling. However, there was room for improvement in the adhesive strength for use in bonding structures.

Patent Document 4 is a publication about a two-component room temperature curing urethane coating waterproofing composition. It contains a solvent, which raises concerns about its adverse effects on the environment, and there is room for improvement in the adhesive strength for use in bonding structures.

The goal is to obtain a urethane resin composition that exhibits high adhesive strength when used to bond structures, and whose cured product itself has film properties that exhibit high maximum stress and high elongation.

The object is to obtain a composition consisting of hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and an amine compound (C) represented by formula (1) and having a number average molecular weight of 500 to 1200.

This urethane resin composition exhibits high adhesive strength when bonding structures, and the film properties of the cured product itself exhibit high maximum stress and high elongation, making it possible to bond a variety of structures.

When an isocyanate compound reacts with an amine compound, a urea bond is produced, which is referred to as urethane in this application for convenience.
The hexamethylene diisocyanate (HDI) of the present invention may be a commercially available product. HDI is sold by Asahi Kasei Corporation, Tosoh Corporation, Mitsui Chemicals, Inc., Wanka Chemical Co., Ltd., etc., and any of them may be used.

The crude MDI (cMDI) of the present application may be a commercially available product. cMDI is sold under the trade names Luplanate M20S, Luplanate M11S, and Luplanate M5S by BASF INOAC Polyurethanes, Millionate MR-100 by Tosoh Corporation, Millionate MR-200 by Tosoh Corporation, Millionate MR-400 by Tosoh Corporation, 44V20L by Sumika Covestro Urethanes, and SUPRASEC5005 by Huntsman. 44V20L is a more suitable material.

The amine compound (C) which is a curing agent and has a number average molecular weight of 500 to 1200 and is represented by formula (1) can be a commercially available product. A specific product name is Elasmer 650P manufactured by Kumiai Chemical Industry Co., Ltd. The number average molecular weight of Elasmer 650P is 888.

The molar ratio of the total isocyanate groups of hexamethylene diisocyanate (A) and crude diphenylmethane diisocyanate (B) to the number of moles of active hydrogen groups of amine compound (C) having a number average molecular weight of 500 to 1200, as represented by formula (1), is (number of moles of isocyanate groups)/(number of moles of active hydrogen groups) = 0.7 to 1.5, more preferably (number of moles of isocyanate groups)/(number of moles of active hydrogen groups) = 0.8 to 1.3.

The mass ratio of hexamethylene diisocyanate (A) and crude diphenylmethane diisocyanate (B) is crude diphenylmethane diisocyanate (B)/hexamethylene diisocyanate (A) = 2-6/4-8, more preferably crude diphenylmethane diisocyanate (B)/hexamethylene diisocyanate (A) = 3-5/5-7.

In addition to hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and the amine compound (C) represented by formula (1) and having a number average molecular weight of 500 to 1200, the urethane resin composition of the present application can also contain glycol-based compounds such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, polyester polyol-based compounds, castor oil-based compounds, and alcohols such as alcohol-containing rubber, within the range that does not impair the adhesive strength and the maximum stress and elongation properties of the film.

In addition to hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and the amine compound (C) represented by formula (1) and having a number average molecular weight of 500 to 1200, an antioxidant can be added to the urethane resin composition of the present application in order to ensure long-term adhesion within a range that does not impair the adhesive strength and the maximum stress and elongation of the film. Examples of the antioxidant include phosphorus-based, hydroquinone-based, bis-tris-polyphenol-based, thiobisphenol-based, and hindered phenol-based antioxidants.
In addition, a silane coupling agent can be added to improve glass adhesion within a range that does not impair the adhesive strength, the maximum stress of the film properties, and the elongation rate. Examples of the silane coupling agent include epoxy silanes such as 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropyltrimethoxysilane, vinyl silanes such as vinyltriethoxysilane and vinyltrimethoxysilane, methacryl silanes and acrylic silanes such as 3-methacryloxypropylmethyldimethoxysilane and 3-acryloxypropyltrimethoxysilane, mercapto silanes such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane, and amino silanes such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

In addition to hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and the amine compound (C) represented by formula (1) and having a number average molecular weight of 500 to 1,200, inorganic fillers such as calcium carbonate, talc, silica, kaolin, calcined kaolin, clay, calcium silicate, calcium sulfate, aluminum oxide (alumina), aluminum hydroxide, aluminum silicate, titanium oxide, zinc oxide, magnesium carbonate, magnesium silicate, zeolite, glass beads, and shirasu balloons can be added to the urethane resin composition of the present application, provided that the adhesive strength and the maximum stress and elongation properties of the coating are not impaired.
In addition, organic fillers such as polyethylene, polypropylene, polymethyl methacrylate, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, nylon, polyethylene terephthalate, polybutylene terephthalate, polystyrene, ABS resin, acrylonitrile-styrene copolymer, and polycarbonate can also be added.

The present invention will be described in more detail below with reference to examples and comparative examples, but these are given as specific examples and are not intended to be limiting. All parts are by weight.

Calculation method for isocyanate groups [mol] of an isocyanate compound The number of moles of isocyanate groups of an isocyanate compound can be calculated by the following formula.
Isocyanate group [mol] = amount added [g] × (NCO [%] / 100) × 1/42

Calculation method for active hydrogen groups [mol] of a curing agent The number of moles of active hydrogen groups of a curing agent can be calculated by the following formula.
Active hydrogen group [mol] = amount added [g] × hydroxyl value [mg KOH/g] × 1/56110

Preparation of a liquid composition of the isocyanate compound of Example 1 In an environment of 23° C., 16.8 g of hexamethylene diisocyanate (HDI, NCO [%] is 50 [%]) and 7.2 g of crude MDI (cMDI) 44V20L (NCO [%] is 31 [%]) were weighed out and stirred with a clean spatula while being careful not to introduce bubbles, to obtain a liquid composition of the isocyanate compound of Example 1.

Preparation of isocyanate compound composition liquids of Examples 2 to 5 and Comparative Examples 1 to 8 The isocyanate compound composition liquids of Examples 2 to 5 and Comparative Examples 1 to 8 were obtained in the proportions shown in Tables 1 and 2 by the same method as for preparation of the isocyanate compound composition liquid of Example 1. Millionate MT (NCO [%] is 33.6 [%]) is monomeric MDI manufactured by Tosoh Corporation. The prepolymer was prepared by weighing out 19.1 g of polypropylene glycol (product name: PP-2000) manufactured by Sanyo Chemical Industries, Ltd. into the kettle of a planetary mixer (product name: PLM-2) manufactured by Inoue Seisakusho Co., Ltd., dehydrating at 100°C and 6.7 kPa, confirming that the moisture content was 500 ppm or less, adding 37.2 g of polymeric MDI (Millionate MR-200) manufactured by Tosoh Corporation, replacing the system with a nitrogen atmosphere, and allowing to react at 80°C for 2 hours, resulting in a prepolymer (NCO [%] was 18.9 [%]).

The curing agents of Examples 1 to 5 and Comparative Examples 1 to 8 are shown in Tables 1 and 2. As the curing agent of Examples 1 to 5, Comparative Example 1, Comparative Example 4, Comparative Example 5, and Comparative Example 8, 100 g of Elasmer 650P (hydroxyl value is 130.4 [mgKOH/g]) was used. As the curing agent of Comparative Examples 2 and 3, 100 g of Elasmer 1000P (hydroxyl value is 254.0 [mgKOH/g]) with a number average molecular weight of 1238 was used. As the curing agent of Comparative Examples 6 and 7, 100 g of Elasmer 250P (hydroxyl value is 96.4 [mgKOH/g]) with a number average molecular weight of 488 was used. In Tables 1 and 2, the isocyanate compound is shown in parentheses as NCO [%], and the curing agent is shown in parentheses as hydroxyl value [mgKOH/g].

Preparation of compositions of Examples 1 to 5 and Comparative Examples 1 to 8 The isocyanate compound and the curing agent were weighed out in the ratios shown in Tables 1 and 2, and stirred with a clean spatula while taking care not to introduce bubbles, to prepare the compositions of Examples 1 to 5 and Comparative Examples 1 to 8.
Note that (moles of isocyanate groups)/(moles of active hydrogen groups) is shown on the first line, the crude MDI (:cMDI)/hexamethylene diisocyanate (:HDI) mass ratio is shown on the second line, and the curing agent/isocyanate mass ratio is shown on the third line. Note that in Comparative Examples 5 and 6, marked with (*) on the second line, monomeric MDI was used instead of crude MDI (:cMDI), so the mass ratio is (monomeric MDI/hexamethylene diisocyanate).
In Comparative Examples 6 and 7, Elastomer 250P was a solid and a uniform composition could not be obtained, so that the film properties and adhesive strength were not measured.

Measurement of Film Properties The solutions of Examples 1 to 5, Comparative Examples 1 to 5, and Comparative Example 8 obtained in the previous section were applied to silicone release paper to an area of approximately 150 mm x 150 mm x 1 mm thick, and incubated in an environment of 23°C/50% RH for 1 day and at 40°C for 2 days to obtain cured films.
Test pieces were prepared by punching out using a dumbbell type No. 3 according to JIS K6251. The physical properties of the coating were measured using a uniaxial testing machine manufactured by INSTRON, product name: 5967. The tensile speed was 100 mm/min, the measurement environment was 23±2° C., and n=5 average.
The evaluation criteria were as follows: for maximum stress, a maximum stress of 30 MPa or more is pass, and a maximum stress of less than 30 MPa is fail. For elongation, a maximum elongation of 300% or more is pass, and a maximum elongation of less than 300% is fail. The results are shown in Tables 4 and 5.

Two SUS430 plates, 25 mm x 100 mm x 1.5 mm thick, were prepared. The liquids of Examples 1 to 5 and Comparative Examples 2 to 4 were applied to the end of one plate at a position 12.5 mm away from the end of the other plate so that the applied amount was 200 g/m2. The end of the other SUS430 plate was then overlapped and fastened with two clips, and incubated in a 23°C/50% RH environment for one day and at 40°C for two days to obtain an adhesive strength test piece. The shear adhesive strength was measured at a tensile speed of 3 mm/min using a uniaxial tester manufactured by INSTRON, product name: 5967. The measurement environment was 23±2°C, and n=5 average. The criteria for judgment were 5 MPa or more as pass, and less than 5 MPa as fail. The results are shown in Tables 4 and 5. In addition, for Comparative Examples 1 to 5 and 8 which were unsatisfactory in terms of film properties, and Comparative Examples 6 and 7 which were unable to obtain a uniform composition, the adhesive strength between SUS430 plates was not confirmed.

Confirmation of adhesive strength of A1100P and SPCC-SD As in the confirmation of adhesive strength of SUS304, confirmation of adhesive strength was carried out using A1100P, an aluminum alloy plate of 25 mm x 100 mm x 1.6 mm thickness, and SPCC-SD, a cold-rolled steel plate with a dull finish of 25 mm x 100 mm x 1.6 mm thickness. The measurement conditions and judgment criteria were the same as those for SUS403. Note that confirmation of adhesive strength of A1100P and SPCC-SD was not carried out for Comparative Examples 1 to 5 and 8, which were rejected for film properties, and for Comparative Examples 6 and 7, which were unable to obtain a uniform composition.

Examples 1 to 5, which are compositions consisting of hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and an amine compound (C) with a number average molecular weight of 500 to 1200 and represented by formula (1), passed all of the film property measurements, including maximum stress, elongation, and adhesive strength measurements using various adherends.

Example 1, which did not use hexamethylene diisocyanate (HDI) as the isocyanate compound, failed both the maximum stress and elongation of the film properties.

Comparative Examples 2 and 3, which used Elastomer 1000P, which has a number average molecular weight outside the range of amine compound (C) with a number average molecular weight of 500 to 1200 as expressed by formula (1), had unacceptable film properties. Comparative Examples 6 and 7, which used Elastomer 250P, which has a number average molecular weight outside the range, did not produce a uniform composition.

Comparative examples 4 and 5, which used monomeric MDI instead of crude MDI (cMDI), passed the elongation test for the film properties, but failed the test for maximum stress.

Comparative Example 8, which used a prepolymer as the isocyanate compound, failed both the maximum stress and elongation measurements of the film properties.

Claims (3)

A composition comprising hexamethylene diisocyanate (A), crude diphenylmethane diisocyanate (B), and an amine compound (C) represented by formula (1) and having a number average molecular weight of 500 to 1,200.

(1)
In the above formula, m=1-2, n=2-3, and R is a polyether. The composition according to claim 1, wherein the total number of moles of isocyanate groups in hexamethylene diisocyanate (A) and crude diphenylmethane diisocyanate (B) and the number of moles of active hydrogen groups in amine compound (C) having a number average molecular weight of 500 to 1200 and represented by formula (1) are (number of moles of isocyanate groups)/(number of moles of active hydrogen groups) = 0.7 to 1.5. The composition according to claim 1 or 2, wherein the mass ratio of hexamethylene diisocyanate (A) and crude diphenylmethane diisocyanate (B) is crude diphenylmethane diisocyanate (B)/hexamethylene diisocyanate (A)=2-6/4-8.