Adhesive composition

Abstract

The objective is to provide an adhesive composition for composite materials (painted steel sheets / gypsum boards) used in applications such as bus panels, which exhibits excellent adhesion and durability after bonding and drying. [Solution] An adhesive composition comprising 100 parts by mass of acrylic emulsion (A), which contains 10 to 90 parts by mass of acrylic emulsion (a1) having a solid content of 20 to 80% by mass and a polymer Tg (glass transition temperature) of 0°C or lower, and 10 to 90 parts by mass of acrylic emulsion (a2) having a solid content of 20 to 80% by mass and a polymer Tg of 20°C or higher, 0.05 to 20 parts by mass of modified polyvinyl alcohol (B) having acetoacetyl groups with a degree of saponification of 95% or higher, 0.5 to 15 parts by mass of diester (C) of a divalent acid represented by the following formula (1), and 0.05 to 10 parts by mass of surfactant (D) on a solid content basis. JPEG2026052276000008.jpg2384 (R 1 , R 2 These are C1-C20 hydrocarbon compounds. 3 (These are hydrocarbons with 2 to 8 carbon atoms.)

Description

[Technical Field]

[0001] This invention relates to adhesive compositions for composite materials (painted steel sheets / gypsum boards) used in applications such as bus panels. [Background technology]

[0002] In bathrooms, composite materials such as bath panels are sometimes used as partitions between the bathroom and the outside. Acrylic emulsion-based adhesives are often used as bonding agents for composite materials. After bonding composite materials (painted steel sheets / gypsum boards) and allowing them to dry, there is a need for adhesive compositions that exhibit excellent adhesion and durability.

[0003] Patent Document 1 is a publication relating to a thermal recording adhesive sheet that is excellent in recording sensitivity and recording travel, and is suitable for distribution management applications. However, there was room for improvement in the acrylic emulsion for this composition to be used as an adhesive composition for composite materials used as bus panels. The usage time of aqueous emulsion-isocyanate compounds or isocyanate polymers can be greatly extended.

[0004] Patent Document 2 is a publication concerning a two-component fast-curing adhesive used in the woodworking industry, such as doors and panels manufactured by flush bonding or V-cut bonding of a core material and a surface material, or laminated timber manufactured by bonding multiple laminae, as well as a method for manufacturing the same and a bonding method thereof. Similar to Patent Document 1, there was room for improvement in the acrylic emulsion for this composition to be used as an adhesive composition for composite materials used as bath panels. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 10-181200 [Patent Document 2] Japanese Patent Publication No. 2002-220575 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0006] The objective is to provide an adhesive composition for composite materials (painted steel sheets / gypsum boards) used in applications such as bus panels, which exhibits excellent adhesion and durability after bonding and drying. [Means for solving the problem]

[0007] 10 to 90 parts by mass of an acrylic emulsion (a1) having a solid content of 20 to 80% by mass and a polymer Tg (glass transition temperature) of 0°C or less, 10 to 90 parts by mass of an acrylic emulsion (a2) having a solid content of 20 to 80% by mass and a polymer Tg of 20°C or higher, For 100 parts by mass of acrylic emulsion (A) containing, 0.05 to 20 parts by mass of modified polyvinyl alcohol (B) having acetoacetyl groups with a degree of saponification of 95% or more, 0.5 to 15 parts by mass of a divalent acid diester (C) represented by the following formula (1), An adhesive composition comprising 0.05 to 10 parts by mass of surfactant (D) on a solid content basis. JPEG2026052276000001.jpg2384 (R 1 , R 2 These are C1-C20 hydrocarbon compounds. 1 , R 2 They can be the same. 3 It is a hydrocarbon having 2 to 8 carbon atoms, and may have branched structures and unsaturated bonds in its structure. [Effects of the Invention]

[0008] This adhesive composition for composite materials, such as those used in bathroom panels, exhibits excellent durability after bonding and drying, thus providing a comfortable living environment. [Best Mode for Carrying Out the Invention]

[0009] The present invention will be described in detail below.

[0010] Acrylic emulsion (A) comprises acrylic emulsion (a1) having a solid content of 20-80% by mass and a polymer Tg of 0°C or lower, and acrylic emulsion (a2) having a solid content of 20-80% by mass and a polymer Tg of 20°C or higher.

[0011] The polymer Tg is the calculated Tg obtained from Fox's formula below. 1 / (Tg(K))=Σ(Mi / Tgi) (In the formula, Mi represents the mass fraction of monomer i that constitutes the polymer, and Tgi represents the glass transition temperature (K) of the homopolymer of monomer i.)

[0012] The solids content of acrylic emulsion (a1) with a polymer Tg of 0°C or lower is 20 to 80% by mass, more preferably 35 to 65% by mass. Similarly, the solids content of acrylic emulsion (a2) with a polymer Tg of 20°C or higher is 20 to 80% by mass, more preferably 35 to 65% by mass.

[0013] The amounts of acrylic emulsion (a1) with a polymer Tg of 0°C or less and acrylic emulsion (a2) with a polymer Tg of 20°C or more added are 10 to 90 parts by mass of acrylic emulsion (a1) with a polymer Tg of 0°C or less and 10 to 90 parts by mass of acrylic emulsion (a2) with a polymer Tg of 20°C or more, and acrylic emulsion (A) is 100 parts by mass.

[0014] As the acrylic emulsion (a1) with a solid content of 20 to 80% by mass and a polymer Tg of 0°C or lower, the product name: UL-2606 (polymer Tg: -42°C, solid content: 50%) is commercially available from Aika Kogyo Co., Ltd. As the acrylic emulsion (a2) with a polymer Tg of 20°C or higher, the product name: DF-105G (polymer Tg: 88°C, solid content: 46%) is commercially available from Aika Kogyo Co., Ltd.

[0015] The addition amount of the modified polyvinyl alcohol (B) having an acetoacetyl group with a saponification degree of 95% or more is 0.05 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the acrylic emulsion (A). As the modified polyvinyl alcohol (B) having an acetoacetyl group with a saponification degree of 95% or more, the product name: Gosenex Z-200 (saponification degree: 99% or more) is commercially available from Mitsubishi Chemical Corporation.

[0016] When adding the modified polyvinyl alcohol (B) having an acetoacetyl group with a saponification degree of 95% or more, it can be dissolved in water and added. The amount of water is about 4 times that of the modified polyvinyl alcohol (B) having an acetoacetyl group with a saponification degree of 95% or more.

[0017] The diester (C) of the divalent acid represented by the formula (1) basically acts as a plasticizer. The addition amount of the diester (C) of the divalent acid represented by the formula (1) is 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the acrylic emulsion (A). JPEG2026052276000002.jpg2384 (R 1 、R 2 are C1 - C20 hydrocarbon compounds. R 1 、R 2 may be the same. R 3 is a hydrocarbon having 2 to 8 carbon atoms and may have a branched structure and an unsaturated bond in its structure.

[0018] For the diester (C) of the divalent acid represented by the formula (1), either a processed product or a reagent can be used. As for chemical products, the following are sold: DBE (dimethyl succinate / dimethyl glutarate / dimethyl adipate = 15~25 / 55~65 / 10~25) from Motori Chemical Group, DINA (diisononyl adipate) from J-Plus Co., Ltd., and DBS (dibutyl sebacate) from Toyokuni Oil Co., Ltd.

[0019] The amount of surfactant (D) added is 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, in terms of solid content, per 100 parts by mass of acrylic emulsion (A). Any type of surfactant can be used, including anionic surfactants, cationic surfactants, and nonionic surfactants. A more suitable surfactant (D) is an anionic surfactant (d1). An anionic surfactant (d1) is commercially available from Kao Corporation under the product name: Emal 2F-30 (solid content: 30% aqueous solution).

[0020] The present invention will be described in more detail below with reference to examples and comparative examples, but these are merely examples and the invention is not limited to them. All quantities are in parts by mass. [Examples]

[0021] <Preparation of the adhesive composition of Example 1> 50g of UL-2606(a1) and 50g of DF-105G(a2) were weighed out and stirred until homogeneous to obtain acrylic emulsion (A). 0.84g of Emal 2F-30 (solids: 0.25g) was added to this emulsion and stirred until homogeneous. Separately, 1.25g of Gosenex Z-200 was dissolved in 5g of water. This aqueous solution of Gosenex Z-200 was mixed with an acrylic emulsion (A) to which Emal 2F-30 had been added, and the mixture was stirred until homogenized. Then, 5g of DBE was added and the mixture was stirred until homogenized to obtain the adhesive composition of Example 1.

[0022] <Preparation of adhesive compositions for Examples 2-7 and Comparative Examples 1-4> Adhesive compositions for Examples 2-7 and Comparative Examples 1-4 were prepared in the same manner as the adhesive composition for Example 1, using the proportions shown in Tables 1 and 2. Diethyl succinate, diethyl suberate, and diethyl dodecanediol were used as reagents. Additionally, CS-12 is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and CS-16 is 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.

[0023] <Steel plate adhesion> The test specimens for steel plate adhesion were prepared by allowing the specimens and adhesive composition to acclimate to a 5°C environment, and all testing was carried out under 5°C conditions. I prepared a painted steel sheet measuring 25mm x 100mm x 0.5mm thick and a gypsum board measuring 45mm x 85mm x 9mm thick. The steel plate was bent at a 90° angle at the 50mm mark to form an L-shape. The plasterboard has paper attached to both sides for protection. I used it as is. The application rate for gypsum board is 55g / m². 2 The adhesive composition was applied using a bar coater. After standing for 30 seconds, an L-shaped steel plate was placed on top, and pressure was applied at 6.5 kPa for 5 seconds, followed by 24 hours of standing. The bonding area was 25 mm x 50 mm. After 24 hours of standing, I held the unbonded portion of the steel plate in my hand and peeled off the bonded area, starting from the L-shaped fold, to check the condition of the protective paper covering the gypsum board. The judging criteria were: a paper destruction rate of 70% or higher was a pass (○), and a paper destruction rate of 70% or less was a fail (×). The results are shown in Tables 3 and 4.

[0024] <High temperature and high humidity creep properties> Similar to the steel plate adhesion test, the high-temperature, high-humidity creep test was also conducted under a 5°C environment, after the test specimens and adhesive compositions had been allowed to acclimate to the environment. A 45mm x 85mm x 9mm thick gypsum board and a 25mm x 100mm x 0.5mm thick painted steel plate were prepared. The end of a 12mm wide masking tape was attached 50mm from the edge of the painted steel plate. This was to prevent the adhesive composition that had seeped into the gypsum board from affecting the creep test to be conducted later. At a temperature of 5°C, the application rate to the gypsum board was 55g / m². 2 The adhesive composition was applied using a bar coater. After standing for 30 seconds, the painted steel plate was overlapped with the end of the masking tape (the opposite side aligned at the 50mm mark) and the short side of the gypsum board, and pressure was applied at 6.5kPa for 5 seconds, followed by 24 hours of standing. The bonding area was 25mm x 50mm. A 200g weight is suspended from the edge of the painted steel plate of this test specimen, and the unbonded portion of the gypsum board is fixed horizontally. This test specimen is then placed in a 60°C / 95%RH environment. The judging criteria were: passing (○) if the participant could hold the object for 60 minutes, and failing (×) if they could not. The results are shown in Tables 3 and 4.

[0025] Examples 1 to 7, which consist of 100 parts by mass of acrylic emulsion (A) containing 10 to 90 parts by mass of acrylic emulsion (a1) having a solid content of 20 to 80% by mass and a polymer Tg (glass transition temperature) of 0°C or lower, and 10 to 90 parts by mass of acrylic emulsion (a2) having a solid content of 20 to 80% by mass and a polymer Tg of 20°C or higher, are further enriched with 0.05 to 20 parts by mass of modified polyvinyl alcohol (B) having acetoacetyl groups with a degree of saponification of 95% or higher, 0.5 to 15 parts by mass of divalent acid diester (C) represented by formula (1), and 0.05 to 10 parts by mass of surfactant (D) on a solid content basis, passed both the steel plate adhesion and high-temperature, high-humidity creep resistance tests.

[0026] Comparative Example 1, which did not contain the divalent acid diester (C) represented by formula (1), Comparative Example 2, which contained a divalent acid diester other than the divalent acid diester (C) represented by formula (1), and Comparative Example 4, which contained 2,2,4-trimethyl-1,3-pentanediol diisobutyrate instead of the divalent acid diester (C) represented by formula (1), all failed to meet the standards for steel plate adhesion. Furthermore, Comparative Example 3, in which 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate was added instead of the divalent acid diester (C) represented by formula (1), failed to meet the high-temperature, high-humidity creep requirements.

[0027] [Table 1]

[0028] [Table 2]

[0029] [Table 3]

[0030] [Table 4]

Claims

1. 10 to 90 parts by mass of an acrylic emulsion (a1) having a solid content of 20 to 80% by mass and a polymer Tg (glass transition temperature) of 0°C or less, 10 to 90 parts by mass of an acrylic emulsion (a2) having a solid content of 20 to 80% by mass and a polymer Tg of 20°C or higher, A 100 parts by mass of acrylic emulsion (A) containing the following: 0.05 to 20 parts by mass of modified polyvinyl alcohol (B) having acetoacetyl groups with a degree of saponification of 95% or more, A divalent acid diester (C) represented by the following formula (1) is used, and 0.5 to 15 parts by mass are used. An adhesive composition comprising 0.05 to 10 parts by mass of surfactant (D) on a solid content basis. (R １ , R ２ These are C1-C20 hydrocarbon compounds. １ , R ２ They can be the same. R ３ It is a hydrocarbon having 2 to 8 carbon atoms, and may have branched structures and unsaturated bonds in its structure.

2. The adhesive composition according to claim 1, wherein the surfactant (D) is an anionic surfactant (d1).

3. An adhesive composition according to claim 1 or claim 2, for use in composite materials used in bath panels.

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