Adhesive composition for waterproof sheets

Abstract

To provide an adhesive composition for a waterproof sheet which solves the problem that a tackifier is used as a conventional adhesive composition so as to improve adhesion to a vinyl chloride resin, when a phenolic resin is used as the tackifier resin, a vinyl chloride resin sheet occasionally causes a color change though enhancing adhesion between the vinyl chloride and an adherend, and can suppress color change of the waterproof sheet without impairing the adhesion.SOLUTION: An adhesive composition for a waterproof sheet contains a nitrile rubber, and a vinyl chloride-vinyl acetate copolymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an adhesive composition for waterproof sheets. [Background technology]

[0002] One known method for waterproofing the rooftops of concrete structures is the sheet waterproofing adhesive method. This method involves bonding a waterproofing sheet to a substrate such as concrete using adhesive or fasteners. Polyvinyl chloride resin sheets are widely used as the waterproofing sheet.

[0003] As adhesives used in sheet waterproofing bonding methods, rubber-based adhesive compositions containing butyl rubber or chloroprene rubber are known. In rubber-based adhesive compositions, phenolic resins such as alkylphenol resins or terpene phenol resins are used as tackifying resins to improve adhesion to waterproofing sheets (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-239981 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, since the rubber-based adhesive composition described in Patent Document 1 contains a phenolic resin as a tackifying resin, if it is used on the rooftops of buildings, etc., it will be exposed to direct sunlight and the waterproof sheet will discolor.

[0006] The present invention has been made in view of the above circumstances, and aims to provide an adhesive composition for waterproof sheets that does not impair adhesion and can suppress discoloration of the waterproof sheet. [Means for solving the problem]

[0007] To solve the above problems, the present invention has the following aspects. [1] An adhesive composition for waterproof sheets comprising nitrile rubber and a vinyl chloride-vinyl acetate copolymer. [2] The waterproof sheet adhesive composition according to [1], comprising 5 to 50 parts by mass of the vinyl chloride-vinyl acetate copolymer with respect to 100 parts by mass of the nitrile rubber. [Effects of the Invention]

[0008] According to the adhesive composition for waterproof sheets of the present invention, the adhesive properties are not impaired and discoloration of the waterproof sheet can be suppressed. [Modes for carrying out the invention]

[0009] [Adhesive composition for waterproof sheets] The adhesive composition for waterproof sheets of the present invention (hereinafter also simply referred to as "adhesive composition") is a solution-type composition containing nitrile rubber and a vinyl chloride-vinyl acetate copolymer.

[0010] The viscosity of the adhesive composition at 23°C is preferably, for example, 1,000 to 10,000 mPa·s, more preferably 1,500 to 8,000 mPa·s, and even more preferably 2,000 to 4,000 mPa·s. When the viscosity of the adhesive composition at 23°C is within the above numerical range, it is easier to apply to the adherend, and workability is further improved. The viscosity of the adhesive composition can be measured using a Brookfield viscometer (BMII type, manufactured by Toki Sangyo Co., Ltd., rotor No. 3) at a rotation speed of 12 rpm, with the sample temperature set to 23°C.

[0011] ≪Nitrile Rubber≫ Nitrile rubber serves as the base material for the adhesive composition of this embodiment. Nitrile rubber, also known as acrylonitrile butadiene rubber (NBR), is a copolymer of butadiene and acrylonitrile. The nitrile rubber is not particularly limited, and any general type can be used. Furthermore, the nitrile rubber may have functional groups such as carboxyl groups introduced into it, and may also contain vulcanizing agents, vulcanization accelerators, softeners, fillers, etc.

[0012] Nitrile rubber is classified into very high nitrile (43% or more by mass of acrylonitrile), high nitrile (36% or more by mass of acrylonitrile and less than 43% by mass), medium-high nitrile (31% or more by mass of acrylonitrile and less than 36% by mass), medium nitrile (25% or more by mass of acrylonitrile and less than 31% by mass), and low nitrile (less than 25% by mass of acrylonitrile) according to the mass of acrylonitrile it is bound to. As for nitrile rubber, high nitrile, medium-high nitrile, and medium nitrile are preferred, with medium-high nitrile being more preferred, due to their good compatibility with polar polymers and excellent balance of oil resistance, heat resistance, and elasticity. Nitrile rubber may be used alone or in combination of two or more types.

[0013] Examples of commercially available nitrile rubber products include NBR manufactured by Zeon Corporation and NBR manufactured by JSR Corporation. Examples of NBRs manufactured by Nippon Zeon Co., Ltd. are all trade names, such as Nipol(registered trademark) 1042, Nipol(registered trademark) 1052J, Nipol(registered trademark) DN202, Nipol(registered trademark) DN212, Nipol(registered trademark) DN219, Nipol(registered trademark) DN225, Nipol(registered trademark) DN3335, Nipol(registered trademark) DN3350, Nipol(registered trademark) DN3390, Nipol(registered trademark) 1043, Nipol(registered trademark) DN302, Nipol(registered trademark) DN302H, Nipol(registered trademark) DN306, Nipol(registered trademark) DN2950, ​​Nipol(registered trademark) DN401, Nipol(registered trademark) DN401L, Nipol(registered trademark) DN406, and Nipol(registered trademark) DN407. As NBR manufactured by JSR Corporation, all are trade names. For example, N238H, N232SH, N237H, N230S, N232S, N237, N233, N230SL, N231L, N230SV, N239SV, N241H, N242S, N250S, N260S, N250SL, etc. can be mentioned.

[0014] ≪Vinyl Chloride-Vinyl Acetate Copolymer≫ The adhesive composition of this embodiment can enhance the adhesiveness to the waterproof sheet by containing a vinyl chloride-vinyl acetate copolymer. In addition, discoloration of the waterproof sheet can be suppressed.

[0015] The vinyl chloride-vinyl acetate copolymer is a copolymer of vinyl chloride and vinyl acetate. In the vinyl chloride-vinyl acetate copolymer, the proportion of the structural unit derived from vinyl chloride is preferably 60 to 99% by mass, more preferably 70 to 95% by mass. When the proportion of the structural unit derived from vinyl chloride is within the above numerical range, the adhesiveness to the waterproof sheet can be further enhanced. Note that the vinyl chloride-vinyl acetate copolymer does not necessarily have to be a copolymer only of the structural units derived from vinyl chloride and vinyl acetate, and may include structural units derived from vinyl alcohol, hydroxyalkyl acrylate, dicarboxylic acid, etc. within a range that does not prevent the object of the present invention.

[0016] The number average molecular weight (Mn) of the vinyl chloride-vinyl acetate copolymer is preferably, for example, 1,000 to 200,000, more preferably 5,000 to 100,000. When the number average molecular weight of the vinyl chloride-vinyl acetate copolymer is at least the above lower limit value, the cohesive force of the vinyl chloride-vinyl acetate copolymer can be enhanced, and the adhesive force of the adhesive composition can be further enhanced. When the number average molecular weight of the vinyl chloride-vinyl acetate copolymer is at most the above upper limit value, the viscosity of the adhesive composition can be reduced, and the workability can be further enhanced. The number average molecular weight of the vinyl chloride-vinyl acetate copolymer is determined by converting the value measured by gel permeation chromatography (GPC) based on the calibration curve with standard polystyrene.

[0017] The average polymerization degree of the vinyl chloride-vinyl acetate copolymer is preferably, for example, from 100 to 1,000, more preferably from 150 to 900, and even more preferably from 200 to 800. When the average polymerization degree of the vinyl chloride-vinyl acetate copolymer is at least the above lower limit value, the cohesive force of the vinyl chloride-vinyl acetate copolymer can be enhanced, and the adhesive force of the adhesive composition can be further enhanced. When the average polymerization degree of the vinyl chloride-vinyl acetate copolymer is at most the above upper limit value, the viscosity of the adhesive composition can be reduced, and the workability can be further enhanced. The average polymerization degree of the vinyl chloride-vinyl acetate copolymer means the average polymerization degree measured in accordance with the "Vinyl Chloride Resin Test Method" annexed to JIS K6720-2:1999.

[0018] The content of the vinyl chloride-vinyl acetate copolymer is preferably, for example, from 5 to 50 parts by mass, more preferably from 10 to 40 parts by mass, and even more preferably from 15 to 30 parts by mass with respect to 100 parts by mass of the nitrile rubber. When the content of the vinyl chloride-vinyl acetate copolymer is at least the above lower limit value, the adhesiveness to the waterproof sheet can be further enhanced. When the content of the vinyl chloride-vinyl acetate copolymer is at most the above upper limit value, the workability can be further enhanced.

[0019] ≪Optional Components≫ The adhesive composition of the present embodiment may contain other components (optional components) other than the nitrile rubber and the vinyl chloride-vinyl acetate copolymer. As the optional components, components usually used in the adhesive composition can be blended. Examples of the optional components include tackifying resins, solvents, various additives, and the like. These optional components may be used alone or in combination of two or more.

[0020] <Tackifying Resin> The tackifying resin is a resin for improving the adhesiveness to the waterproof sheet. In particular, when the waterproof sheet is a vinyl chloride resin, the adhesive composition preferably contains a tackifying resin. Note that the above-described vinyl chloride-vinyl acetate copolymer is one kind of tackifying resin.

[0021] Examples of tackifying resins include rosin-based resins, terpene-based resins, petroleum-based resins, phenolic resins, coumarone-indene resins, thermoplastic urethane resins, and acrylic resins. Coumarone-indene resins and phenolic resins are preferred as tackifying resins because they have good compatibility with nitrile rubber and vinyl chloride-vinyl acetate copolymers and good tackiness. However, when phenolic resin is used as the tackifying resin, the waterproof sheet is prone to discoloration. For this reason, it is preferable not to use phenolic resin as the tackifying resin. This is thought to be because, when phenolic resin is used as the tackifying resin, it discolors due to light and heat in the presence of nitrile rubber.

[0022] Coumaron-indene resin is a copolymer mainly composed of coumaron, indene, and styrene. Commercially available products of coumaron-indene resin include, for example, Nitresin® Coumaron G-90, Nitresin® Coumaron G-100N, Nitresin® Coumaron V-120, and Nitresin® Coumaron V-120S (all manufactured by Nippon Paint Chemical Co., Ltd.).

[0023] When the adhesive composition contains a tackifying resin, the content of the tackifying resin is preferably 10 to 100 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 30 to 80 parts by mass, per 100 parts by mass of nitrile rubber. If the content of the tackifying resin is above the lower limit, the adhesion to the waterproof sheet can be further improved. If the content of the tackifying resin is below the upper limit, the viscosity of the adhesive composition can be reduced, and the workability can be further improved.

[0024] <Solvent> As the solvent, a solvent commonly used in adhesive compositions can be used. Examples of solvents include n-hexane (7.3), butyl acetate (8.5), xylene (8.8), toluene (8.8), ethyl acetate (9.0), benzene (9.2), dibutyl phthalate (9.4), acetone (10.0), isopropanol (11.5), acetonitrile (11.9), dimethylformamide (12.0), acetic acid (12.6), ethanol (12.7), cresol (13.3), formic acid (13.5), ethylene glycol (14.2), phenol (14.5), methanol (14.5-14.8), etc. The values ​​in parentheses represent the solubility parameter (also called SP value) of the solvent (cal / cm³). 3 ) 1 / 2 ) represents. The solubility parameter of a solvent refers to the Hildebrand solubility parameter. The solvent may be used alone or in combination of two or more types.

[0025] The solvent solubility parameter is preferably, for example, 7.0 to 11.5, more preferably 7.5 to 11.0, and even more preferably 8.0 to 10.5. When the solvent solubility parameter is within the above numerical range, the compatibility with nitrile rubber can be further enhanced.

[0026] The solvent content is preferably 30 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 80% by mass, based on the total mass of the adhesive composition. If the solvent content is above the lower limit, the viscosity of the adhesive composition can be reduced, and workability can be further improved. If the solvent content is below the upper limit, adhesion can be further improved.

[0027] The solvent content is preferably 100 to 800 parts by mass, more preferably 200 to 700 parts by mass, and even more preferably 300 to 600 parts by mass, per 100 parts by mass of nitrile rubber. If the solvent content is above the lower limit, the viscosity of the adhesive composition can be reduced, and workability can be further improved. If the solvent content is below the upper limit, adhesion can be further improved.

[0028] <Additives> Examples of additives include fillers, plasticizers, stabilizers, antistatic agents, flame retardants, lubricants, pigments, foaming agents, fungicides, and crosslinking agents. Examples of crosslinking agents include zinc oxide, salicylic acid, and water.

[0029] [Method for manufacturing adhesive composition] The adhesive composition of this embodiment is obtained by mixing nitrile rubber, vinyl chloride-vinyl acetate copolymer, and optionally other components using conventionally known methods. For example, the above components can be blended and kneaded at room temperature or under heating using a mixer, roll, kneader, etc., or the components can be dissolved and mixed using a suitable solvent. Each component may be obtained through synthesis or may be a commercially available product.

[0030] [How to use adhesive compositions] One method of using the adhesive is to apply the adhesive composition to one or both adherends, butt the adherends together so that the adhesive composition is positioned between them, and then allow the adhesive composition to cure. The adhesive composition of this embodiment can be applied by any method. It can be applied at low temperatures, such as room temperature (for example, 5 to 35°C), and can also be applied after heating if necessary. The adhesive composition can be applied to the substrate by extruding it in a bead, monofilament, or swirl pattern using a coating robot. Mechanical application methods such as caulking guns or other manual application means can also be used. Furthermore, the adhesive composition can be applied to the substrate using a jet spray or streaming method.

[0031] The adhesive composition of this embodiment exhibits excellent adhesion and can suppress discoloration of waterproof sheets. For this reason, it is suitable for bonding waterproof sheets used on the roofs of concrete structures to concrete and the like. Since the effects of the present invention can be more significantly obtained, a waterproof sheet made of polyvinyl chloride is preferred as the waterproof sheet. In other words, the adhesive composition of this embodiment is preferably for use with a vinyl chloride waterproof sheet.

[0032] According to the adhesive composition of this embodiment, the adhesive properties are excellent, allowing waterproof sheets installed on the rooftops of concrete structures and the like to be used for extended periods without replacement. According to the adhesive composition of this embodiment, discoloration of the waterproof sheet can be suppressed, thus allowing the appearance of the rooftops of concrete structures to be maintained for a long period of time. [Examples]

[0033] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The raw materials used in this embodiment are as shown in the [Raw Materials Used] section below.

[0034] [Raw materials used] ≪Nitrile Rubber≫ • Acrylonitrile butadiene rubber (NBR): Medium-high nitrile, acrylonitrile content 35% by mass, product name "N230S", manufactured by JSR Corporation. ≪Vinyl chloride-vinyl acetate copolymer≫ • Vinyl chloride-vinyl acetate copolymer: Average degree of polymerization 680, product name "Kanevinyl (registered trademark) MB1008", manufactured by Kaneka Corporation.

[0035] ≪Optional ingredients≫ <Adhesive-granting resin> • Coumaron-Indene resin: Product name "Knit Resin (registered trademark) Coumaron V-120", manufactured by Nippon Paint Chemical Co., Ltd. • Alkylphenol resin: Product name "CKM-908", manufactured by Aica Kogyo Co., Ltd. • Dihydrazide adipic acid: Formaldehyde catcher, trade name "ChemCatch (registered trademark) H-6000HS", manufactured by Otsuka Chemical Co., Ltd.

[0036] [Examples 1-4, Comparative Examples 1-3] An adhesive composition was prepared by blending, mixing, and stirring each component in the parts by mass shown in Table 1. The adhesive compositions of each example were subjected to the following performance tests to evaluate adhesiveness, the degree of discoloration of the waterproof sheet (PVC sheet contamination), and workability. In the table, "-" in the column of composition means that the component is not contained.

[0037] <Viscosity> For the adhesive composition obtained in each example, the viscosity was measured at a rotational speed of 12 rpm using a Brookfield viscometer (Model BMII, manufactured by Toki Sangyo Co., Ltd., rotor No. 3) under an environment of 23°C. The results are shown in Table 1.

[0038] <Adhesive strength test> (180-degree peel adhesion strength test) In accordance with JIS K6854-2:1999 "Adhesives - Peel adhesion strength test methods - Part 2: 180-degree peel", the 180-degree peel adhesion strength was measured. The size of the test specimen used for the measurement was as follows. · Substrate: Mortar, 70 mm × 150 mm × 10 mm. · Waterproof sheet: PVC (polyvinyl chloride resin) sheet, 25 mm × 200 mm × 2 mm.

[0039] The adhesive composition obtained in each example was applied to the respective adhesive surfaces of the substrate and the waterproof sheet using a toothed trowel specified in JIS A5536:2015 "Adhesives for floor finishing materials". After allowing an open time (lamination time) of 20 minutes, they were laminated so that the teeth formed a cross. The substrate and the waterproof sheet were crimped using a hand roller and cured for 168 hours under an environment of 23°C and 50% RH (normal state). Then, a 180-degree peel adhesion strength test was conducted at a test speed of 200 mm / min. The adhesive strength was evaluated based on the following evaluation criteria. The results are shown in Table 1. 《Evaluation criteria》 ○: The 180-degree peel adhesion strength is 1.5 N / mm or more. ×: The 180-degree peel adhesion strength is less than 1.5 N / mm.

[0040] <PVC sheet contamination> The adhesive compositions obtained in each example were applied to the respective adhesive surfaces of the base material and the waterproof sheet using a comb-toothed trowel specified in JIS A5536:2015 "Adhesives for Floor Finishing Materials". After allowing an open time of 20 minutes, they were bonded together so that the comb teeth formed a cross. The base material and the waterproof sheet were crimped using a hand roller and cured for 168 hours in an environment of 23°C and 50% RH (normal state). Thereafter, the following exposure test was conducted. The size of the test specimens was as follows. · Base material: Stainless steel, 70 mm × 150 mm × 0.8 mm. · Waterproof sheet: PVC sheet, 70 mm × 150 mm × 2 mm.

[0041] (Sunshine Weatherometer Exposure Test) The test specimens of each example were set in a sunshine weatherometer (S80B, manufactured by Suga Test Instruments Co., Ltd.) and an exposure test was conducted. The exposure conditions were in accordance with the WS-A method described in "6.2 Exposure Test Method by Open Frame Carbon Arc Lamp" of JIS A1415:2013 "Exposure Test Method of Polymer Building Materials by Laboratory Light Source". The exposure time was 312 hours. The L value, a value, and b value of the PVC sheet before and after exposure were measured, the average value of the color difference ΔE was calculated based on the following formula (2), and the PVC sheet stainability was evaluated based on the following evaluation criteria. The smaller the value of ΔE, the less the contamination of the PVC sheet and the more the discoloration of the waterproof sheet can be suppressed. The results are shown in Table 1. 《Evaluation Criteria》 ○: The value of ΔE is less than 2.00. ×: The value of ΔE is 2.00 or more.

[0042] ΔE = [(ΔL * ) 2 + (Δa * ) 2 + (Δb * ) 2 1 / 2 ···(2) In formula (2), ΔL * represents the difference in the L value of the PVC sheet before and after exposure. Δa * represents the difference in the a value of the PVC sheet before and after exposure. Δb * ​This represents the difference in the b-value of the PVC sheet before and after exposure.

[0043] <Workability> The adhesive compositions obtained in each example were applied to the bonding surfaces of the substrate and waterproof sheet using a notched trowel as specified in JIS A5536:2015 "Adhesives for floor finishing materials," and the ease of application (workability) was evaluated based on the following evaluation criteria. The results are shown in Table 1. Evaluation Criteria ◎: Can be applied smoothly. ○: Although it has high viscosity, it can be applied. ×: Cannot be applied.

[0044] [Table 1]

[0045] As shown in Table 1, Examples 1 to 4 to which the present invention was applied demonstrated excellent adhesive strength and PVC sheet stain resistance. In contrast, Comparative Examples 1-3, which do not contain vinyl chloride-vinyl acetate copolymer, were found to be inferior to Examples 1-4 in at least one of the adhesive strength and PVC sheet staining properties.

[0046] These results confirm that the adhesive composition for waterproof sheets of the present invention does not impair adhesion and can suppress discoloration of the waterproof sheet.

Claims

1. A one-component adhesive composition for waterproof sheets, comprising nitrile rubber and a vinyl chloride-vinyl acetate copolymer.

2. The one-component adhesive composition for waterproof sheets according to claim 1, comprising 5 to 50 parts by mass of the vinyl chloride-vinyl acetate copolymer with respect to 100 parts by mass of the nitrile rubber.

3. A one-component adhesive composition for waterproof sheets according to claim 1 or 2, comprising a tackifying resin.

4. The one-component adhesive composition for waterproof sheets according to claim 3, wherein the tackifying resin comprises any of rosin-based resin, terpene-based resin, coumarone-indene resin, thermoplastic urethane resin, or acrylic resin.

5. The one-component adhesive composition for waterproof sheets according to claim 3, wherein the tackifying resin comprises coumarone-indene resin.

6. The one-component adhesive composition for waterproof sheets according to claim 1 or 2, comprising a solvent having a solubility parameter of 7.0 to 11.5.

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