JP2008285554A - Aqueous emulsion type adhesive composition and adhesive tape or adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous emulsion type adhesive composition excellent in heat resistance and adhesiveness and having a characteristic of low volatile organic compound (VOC) content and an adhesive tape or an adhesive sheet. <P>SOLUTION: The aqueous emulsion type adhesive composition comprises a (meth)acrylic acid 4-12C alkyl ester, a hydroxyl group-containing monomer, etc., as components and further comprises a rosin-based tackifier resin having 140-170°C softening temperature and being emulsified. The adhesive composition has 15-60 mass% gel content left as a solid content without causing dissolution when dissolving it into tetrahydrofuran and contains a component having 50,000-500,000 weight average molecular weight expressed in terms of polystyrene as a dissolution content and has a glass transition point of -75 to -20°C and has heat resistance. The adhesive composition excellent in heat resistance is formed by combination with the adhesiveness-imparting resin, etc. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aqueous emulsion-type pressure-sensitive adhesive composition having excellent heat resistance and a very low volatile organic compound (VOC), and a pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet.

  Conventionally, adhesives for foam base materials have used organic solvent type adhesives, which has been a problem from the viewpoint of air pollution due to volatile solvents during factory production, improvement of working environment, and risk of fire . Therefore, a water-based emulsion-type pressure-sensitive adhesive for a foam base material has been developed and has been used instead of an organic solvent-type pressure-sensitive adhesive (see Patent Document 1).

  In addition, the tackifying resin used here is usually a rosin resin or the like dissolved in an organic solvent that is symmetric with respect to laws and regulations such as toluene and xylene, and further emulsified into a water-based emulsion using a surfactant. The solvent is used after desolvation by means such as reduced pressure. However, organic solvents such as toluene and xylene that cannot be removed remain in the water-based emulsion of the tackifying resin, and the guideline value for the indoor concentration of chemical substances included in the guidelines set by the Ministry of Health, Labor and Welfare in 2002 is increased. It was an environmental problem such as sick house (indoor air pollution). Therefore, an alternative to the organic solvent-type pressure-sensitive adhesive is provided as a water-based emulsion-type pressure-sensitive adhesive, and a water-based emulsion-type pressure-sensitive adhesive having a very low volatile organic compound (VOC) has been developed (see Patent Document 2).

Japanese Patent Laid-Open No. 11-131034 JP-A-2005-307114

  An object of the present invention is to provide a water-based emulsion-type pressure-sensitive adhesive composition that has superior heat resistance and low VOC characteristics as compared with conventional water-based pressure-sensitive adhesives. Moreover, the adhesive tape or adhesive sheet formed by apply | coating the adhesive composition is provided. In addition, the heat resistance in this invention refers to evaluation by the softening point of an adhesive and a constant load peeling test.

  This inventor discovered that the said subject could be solved by the combination of specific acrylic emulsion and tackifying resin among adhesive resin materials. That is, according to the present invention, a pressure-sensitive adhesive composition characterized by low VOC that does not adversely affect heat resistance and the environment is provided. In particular, when a foam is used as the base material, the adhesiveness with the foam base material is greatly improved, and adhesive properties such as heat resistance can be improved.

  [1] (A) (a) 65 to 99.9 parts by mass of (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group, and (b) 0.1 to 0.1% of hydroxyl group-containing monomer. Copolymer obtained by emulsion polymerization of 20 parts by mass and (c) 0 to 27 parts by mass of other polymerizable monomers [where (a) + (b) + (c) = 100 parts by mass]. When the polymer emulsion contains (B) 1 to 30 parts by mass of a rosin-based tackifying resin having a softening temperature of 140 to 170 ° C. and the resin emulsified, and dissolved in tetrahydrofuran Furthermore, when the gel content remaining as a solid content without being dissolved is 15 to 60% by mass and the tetrahydrofuran content is measured by gel permeation chromatography (GPC), Ren reduced weight average molecular weight (Mw) of 50,000 to 500,000 an aqueous emulsion-type PSA composition is.

  [2] The water-based emulsion-type pressure-sensitive adhesive composition according to [1], wherein the (meth) acrylic acid alkyl ester is butyl (meth) acrylate and / or 2-ethylhexyl (meth) acrylate.

  [3] The water-based emulsion-type pressure-sensitive adhesive composition according to [1] or [2], wherein the (b) hydroxyl group-containing monomer is 2-hydroxyethyl (meth) acrylate.

  [4] The water-based emulsion-type pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the glass transition point of the pressure-sensitive adhesive composition is −75 to −20 ° C.

  [5] The water-based emulsion-type pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the rosin-based tackifying resin is a solvent-free type tackifying resin.

[6] When the pressure-sensitive adhesive composition is measured by the Tedlar bag method, the total concentration of formaldehyde, acetaldehyde, toluene, ethylbenzene, xylene, styrene and tetradecane in the volatile organic compound (VOC) is 4.5 μg / 80 cm ² or less. The water-based emulsion-type pressure-sensitive adhesive composition according to any one of [1] to [5].

  [7] A pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet obtained by applying the water-based emulsion-type pressure-sensitive adhesive composition according to any one of [1] to [6] to one side or both sides of a foam substrate.

  [8] A pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet obtained by applying the water-based emulsion type pressure-sensitive adhesive composition according to any one of [1] to [6] to one side or both sides of a resin substrate.

  [9] A pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet obtained by applying the water-based emulsion type pressure-sensitive adhesive composition according to any one of [1] to [6] to one side or both sides of a fibrous base material.

  According to the water-based emulsion-type pressure-sensitive adhesive composition of the present invention, a pressure-sensitive adhesive that can withstand a high temperature of 80 ° C. is provided in a test of the softening point, which is one of heat resistance of the pressure-sensitive adhesive, and an organic solvent is not used. As a result, low VOC is achieved. For this reason, a thick house, air pollution, and work environment are improved, and an aqueous emulsion-type pressure-sensitive adhesive composition with less environmental load is provided.

  Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

  The aqueous emulsion-type pressure-sensitive adhesive composition of the present invention comprises (A) (a) (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group, 65 to 99.9 parts by mass, and (b) hydroxyl group. 0.1 to 20 parts by mass of the group-containing monomer, and (c) 0 to 27 parts by mass of other polymerizable monomers [provided that (a) + (b) + (c) = 100 parts by mass] A copolymer emulsion obtained by emulsion polymerization, and (B) 1 to 30 parts by mass of a rosin-based tackifying resin having a softening temperature of 140 to 170 ° C. and the resin emulsified. To do.

  The (meth) acrylic acid alkyl ester used in the present invention is an alkyl ester having 4 to 12 carbon atoms in the alkyl group. For example, n-butyl (meth) acrylate, i-butyl (meth) acrylate, sec-butyl ( (Meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2- Mention ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, etc. It can be. The said (meth) acrylic-acid alkylester may be used individually by 1 type, or may mix and use 2 or more types.

  Among these monomers, butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferably used, and butyl (meth) acrylate is preferably used because an adhesive having excellent adhesiveness can be obtained. Is more preferable.

  (A) The usage-amount of the (meth) acrylic-acid alkylester is 65-99.9 mass parts in (A) component, Preferably, it is 70-98 mass parts, More preferably, it is 75-97 mass parts. If the amount is less than 65 parts by mass, the tackiness of the pressure-sensitive adhesive composition (hereinafter, “tack” refers to evaluation by a weight tack test) is insufficient, while if it exceeds 99.9 parts by mass, the pressure-sensitive adhesive composition has insufficient adhesive strength. It becomes.

  Examples of the hydroxyl group-containing monomer used in the present invention include hydroxystyrene, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, and trans-4-hydroxy-2. -Butene, 3-hydroxy-2-methyl-1-propene, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and the like.

  The content of the (b) hydroxyl group-containing monomer in the component (A) is preferably from 0.1 to 20 parts by mass, more preferably from 0.2 to 17 parts by mass, still more preferably from 0.5 to 15 parts by mass. When the content of the hydroxyl group-containing monomer is less than 0.1 parts by mass, the adhesive strength of the pressure-sensitive adhesive composition (hereinafter, the adhesive strength refers to evaluation by a 90 ° peel test) is insufficient, while 20 When it exceeds the mass part, the tackiness of the pressure-sensitive adhesive composition becomes insufficient.

  The content of (c) other polymerizable monomer in the component (A) is preferably 0 to 27 parts by mass, more preferably 0.5 to 20 parts by mass, and still more preferably 1 to 15 parts. Part by mass. When this monomer exceeds 27 parts by mass, the tackiness of the pressure-sensitive adhesive composition becomes insufficient.

  Examples of other polymerizable monomers used in the present invention include (meth) acrylic acid alkyl esters having 1 to 3 carbon atoms in alkyl groups such as methyl methacrylate and ethyl acrylate; styrene, α-methylstyrene, 4 -Methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 3,4-diethylstyrene, 2 Aromatic vinyl monomers such as -chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 4-t-butylstyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, 1-vinylnaphthalene Body; (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxy Acid amide compounds such as til (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N′-methylenebisacrylamide, diacetone acrylamide, maleic acid amide, maleimide; vinyl cyanide compounds such as (meth) acrylonitrile, Α, β-unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, ethyl acrylic acid, itaconic acid, maleic acid, maleic anhydride, maleic acid monoester, and crotonic acid.

  Hydroxyl group-containing vinyl monomers such as N-methylol vinyl ether and 2-hydroxyethyl vinyl ether; amino group-containing vinyl monomers such as 2-aminoethyl vinyl ether; 1,1,1-trimethylamine (meth) acrylimide, 1 -Methyl-1-ethylamine (meth) acrylimide, 1,1-dimethyl-1- (2-hydroxypropyl) amine (meth) acrylimide, 1,1-dimethyl-1- (2'-phenyl-2'- Hydroxyethyl) amine (meth) acrylimide, amineimide group-containing vinyl monomers such as 1,1-dimethyl-1imide; epoxy group-containing vinyl monomers such as allyl glycidyl ether.

  4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1, Piperidine monomers such as 2,2,6,6-pentamethylpiperidine; polyfunctional monomers such as divinylbenzene;

  Polymerizable functionalities such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxylane Examples include silane coupling agents having a group (glycidoxy group, methacryloxy group, acryloxy group, etc.), and other dicaprolactones. These monomers may be used alone or in combination of two or more. Among these monomers, it is preferable to use methyl methacrylate and acrylic acid.

  For the synthesis (copolymerization) of the component (A) that is the base emulsion of the adhesive composition of the present invention, a usual emulsion polymerization method is used. An acrylic emulsion containing the (meth) acrylate copolymer (A) component is obtained by a method of emulsion polymerization of the monomers a to c in the presence of an emulsifier, water and a polymerization initiator, and this copolymer is obtained. An emulsion can be used as a raw material of the pressure-sensitive adhesive composition of the present invention.

  Component (A): The method and conditions for emulsion polymerization of the (meth) acrylic acid alkyl ester copolymer emulsion are not particularly limited, and conventionally known methods and conditions can be employed. For example, polymerization initiators such as nonionic, anionic or cationic emulsifiers such as polyoxyethylene nonylphenyl ether, sodium dodecylbenzenesulfonate, dodecyltrimethylammonium chloride, persulfates, azobisisobutyronitrile, peroxides, etc. , Butyl mercaptan, dodecyl mercaptan, isopropyl alcohol, methanol, carbon tetrachloride, and other molecular weight modifiers, and if necessary, additives such as antifoaming agents, thickeners, preservatives, and so on. In general, the copolymerization is carried out in an inert atmosphere.

  As a method for adding the monomer mixture at the time of emulsion polymerization, for example, the monomer mixture is added as it is or as a pre-emulsion previously emulsified and dispersed together with an emulsifier in an aqueous medium, or a part or all of the monomer mixture or pre-emulsion is added. A method of continuously or intermittently adding can be used. In addition, a seed emulsion polymerization method using a copolymer emulsion produced from a part of the monomer mixture as a seed in advance can be employed. Furthermore, after this emulsion polymerization is completed, for example, an operation in which an organic oxide such as benzoyl peroxide is added in an amount of 0.2 parts by mass or less with respect to 100 parts by mass in terms of solid content of (meth) acrylic acid alkyl ester copolymer emulsion. In addition, by blowing steam into the copolymer emulsion, heating, and performing distillation under reduced pressure, the amount of residual monomer can be reduced, and as a result, volatile organic compounds (VOC) can be reduced. It becomes.

  (B) Rosin-based tackifying resin: The tackifying resin is divided into petroleum resin-based and natural resin-based, and rosin-based tackifying resin is included in the natural resin-based. The rosin-based tackifier resin has good compatibility with the (meth) acrylic acid alkyl ester copolymer resin and has polarity. The tackifying resin is blended in consideration of compatibility with the resin used in order to improve the adhesion to various substrates. The tackifying resin used in the present invention is preferably a rosin-based tackifying resin, and in particular, has a softening temperature of 140 to 170 ° C. If the softening temperature is low, the adhesive strength is lowered.

  Moreover, it is preferable that the tackifying resin is emulsified and further made into a solvent-free tackifying resin. The emulsification method of the tackifying resin is not particularly limited, and any method such as a high-pressure emulsification method, a reverse emulsification method, an ultrasonic emulsification method, and a solvent emulsification method, which are known emulsification methods, may be employed. For example, when using the high pressure emulsification method, the tackifying resin does not fall under the sick house designated chemical substances set by the Ministry of Health, Labor and Welfare, such as toluene, xylene, styrene, di-n-butyl phthalate, di-2-ethylhexyl phthalate, And, after dissolving the rosin resin, for example, in a solvent such as ethyl acetate or methylcyclohexane, an emulsifier and soft water are added and emulsified using a high-pressure emulsifier under a pressure condition of about 10 to 50 MPa, and then the pressure is reduced. The solvent may be removed.

  The pressure-sensitive adhesive composition of the present invention contains 1 to 30 parts by mass of a rosin-based tackifier resin (tackifier) having a softening temperature of 140 to 170 ° C. with respect to 100 parts by mass in terms of solids of the water-based emulsion type pressure-sensitive adhesive. Well, Preferably, it is a case where 3-25 mass parts of tackifiers are contained. More preferably, it is a case containing 5-20 mass parts. By adding this tackifier, the heat resistance of the pressure-sensitive adhesive composition is improved, but if the tackifier is less than 1 part by mass, the effect of using the tackifier is not seen and the heat resistance of the pressure-sensitive adhesive composition becomes insufficient, Moreover, when it exceeds 30 mass parts, the adhesive force of an adhesive composition will become inadequate.

  The pressure-sensitive adhesive composition of the present invention has an excellent balance of tack and cohesive force by blending a rosin-based tackifier resin as a tackifier with a high softening temperature, and has excellent adhesion to adherends such as polyolefin resins. And heat resistance (softening point, constant load peeling) is improved.

  The tetrahydrofuran gel content, which is a solid content not dissolved in tetrahydrofuran when the pressure-sensitive adhesive composition of the present invention in which the component (A) and the tackifying resin (B) are mixed in tetrahydrofuran, is 15 to 60% by mass, Preferably, it is 20-50 mass%, More preferably, it is 25-45 mass%. When the tetrahydrofuran gel content is less than 15% by mass or exceeds 60% by mass, the heat resistance of the pressure-sensitive adhesive composition becomes insufficient.

  Weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC) of the dissolved portion dissolved in tetrahydrofuran when the pressure-sensitive adhesive composition of the present invention in which component (A) and tackifying resin (B) are mixed in tetrahydrofuran is dissolved. , “Mw”) may be 50,000 to 500,000, preferably 100,000 to 400,000. More preferably, it is 150,000 to 300,000. When Mw is less than 50,000 or exceeds 500,000, the heat resistance of the pressure-sensitive adhesive composition becomes insufficient.

  The glass transition point (Tg) of the pressure-sensitive adhesive composition obtained by mixing the component (A) and the component (B) is preferably −70 to −20 ° C., and preferably −65 to −30 ° C. More preferably, it is −60 to −40 ° C. When Tg is less than −70 ° C., the adhesive strength of the pressure-sensitive adhesive composition becomes insufficient, and when it exceeds −20 ° C., tackiness of the pressure-sensitive adhesive becomes insufficient.

The pressure-sensitive adhesive composition of the present invention is a water-based emulsion-type pressure-sensitive adhesive composition that does not use an organic solvent, and a pressure-sensitive adhesive having a low environmental load can be obtained. The concentration of the volatile organic compound (VOC) measured by the Tedlar bag method of the obtained adhesive is the total concentration of formaldehyde, acetaldehyde, toluene, ethylbenzene, xylene, styrene, and tetradecane, and should be less than 4.5 μg / 80 cm ^2. When it is possible to blend the pressure-sensitive adhesive composition, it can be 2.0 μg / 80 cm ² or less, and when it is more preferably blended, it can be 1.0 μg / 80 cm ² or less. When the volatile organic compound (VOC) concentration is 4.5 μg / 80 cm ² or more, it exceeds the guidelines for volatile organic compounds (VOC) issued by the Ministry of Health, Labor and Welfare.

As described above, the water-based emulsion-type pressure-sensitive adhesive composition of the present invention is obtained by mixing the component (A) and the (B) tackifying resin at an appropriate blending ratio, so that the heat resistance ( While the softening point was about 60 ° C., the pressure-sensitive adhesive composition of the present invention has a high heat resistance (softening point) of 80 ° C. Moreover, the adhesive force has improved the adhesiveness with respect to a rough surface like a foam base material, and is higher than the conventional adhesive composition. Regarding the volatile organic compound (VOC), in the conventional pressure-sensitive adhesive composition, it was about 8 μg / 80 cm ^2. However, the pressure-sensitive adhesive composition of the present invention is excellent in low VOC property, and the VOC is 1 μg / 80 cm ^2. It is possible to:

  The water-based emulsion type pressure-sensitive adhesive composition of the present invention includes pigments, plasticizers, tackifiers other than (B), protective colloid agents, antifoaming agents, antiseptics, fungicides, wetting agents, thickeners, Additives such as anti-aging agents and ultraviolet absorbers can be blended. Moreover, a crosslinking agent can also be mix | blended. Examples of the crosslinking agent to be used include epoxy-based, isocyanate-based, and aziridine-based compounds, and the addition amount is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass (in terms of solid content) of the pressure-sensitive adhesive composition.

  A pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet can be obtained by applying the water-based emulsion-type pressure-sensitive adhesive composition of the present invention to one or both sides of a foam substrate. Examples of the material constituting the foam base material include urethane foam and polyethylene foam. By applying the water-based emulsion-type pressure-sensitive adhesive composition of the present invention to such a foam substrate, a pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet having excellent heat resistance can be obtained.

  Moreover, the adhesive tape or adhesive sheet formed by apply | coating the water-system emulsion-type adhesive composition of the above-mentioned this invention to the single side | surface or both surfaces of resin-made base materials can be obtained. Examples of the material constituting the resin substrate include polyolefin resin films such as PET, PP, polyethylene, and vinyl chloride. By applying the water-based emulsion-type pressure-sensitive adhesive composition of the present invention to such a resin substrate, a pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet having excellent heat resistance can be obtained.

  Furthermore, the adhesive tape or adhesive sheet formed by apply | coating the aqueous emulsion type adhesive composition of the above-mentioned this invention to the single side | surface or both surfaces of a fibrous base material can be obtained. Examples of the material constituting the fibrous base material include non-woven fabric such as rayon and polyester, and paper. By applying the water-based emulsion-type pressure-sensitive adhesive composition of the present invention to such a fibrous base material, a pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet having excellent heat resistance can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

  As shown in Table 1, the pressure-sensitive adhesive compositions of Examples 1 to 7 are (B) rosin-based tackifier with respect to (A) emulsion [(a) + (b) + (c) = 100 parts by mass]. A resin was blended to obtain an aqueous emulsion-type pressure-sensitive adhesive composition. About the obtained water-system emulsion-type adhesive composition, the tetrahydrofuran gel part (insoluble part), the polystyrene conversion weight average molecular weight (Mw) of a dissolved part, and the glass transition point were measured.

  In Comparative Example 1, (c) 30 parts by mass of other polymerizable monomer was used, and the same measurement as in the Example was performed.

  In Comparative Example 2, the same measurement as in Example was performed with 23 parts by mass of the (b) hydroxyl group-containing monomer.

  Comparative Example 3 is a water-based emulsion-type pressure-sensitive adhesive in which the tetrahydrofuran gel content is increased by using an emulsion (A) in which the molecular weight modifier (dodecyl mercaptan) is reduced and the polystyrene-equivalent weight average molecular weight is increased as compared with Example 1. A composition was obtained. About the obtained water-system emulsion-type adhesive composition, the measurement similar to an Example was implemented.

  In Comparative Example 4, a water-based emulsion-type pressure-sensitive adhesive composition having a reduced tetrahydrofuran gel content was obtained by using an emulsion (A) in which the molecular weight was decreased by increasing the molecular weight modifier (dodecyl mercaptan) as compared with Example 1. It was. About the obtained water-system emulsion-type adhesive composition, the measurement similar to an Example was implemented.

  In Comparative Example 5, compared to Example 1, the aqueous emulsion-type pressure-sensitive adhesive composition prepared by using (A) emulsion in which the molecular weight modifier (dodecyl mercaptan) was decreased and the molecular weight was increased was the same as in Example 1. The measurement of was carried out.

  In Comparative Example 6, the same measurement as in Example was performed using (A) emulsion having a glass transition point of −17 ° C.

  In Comparative Example 7, (B) tackifying resin having a softening temperature of 80 ° C. was added to (A) emulsion of Example 1, and the same measurement as in Example was performed.

  In Comparative Example 8, 45 parts by mass of (B) tackifying resin having a softening temperature of 160 ° C. was blended with the (A) emulsion of Example 1, and the same measurement as in Example was performed.

  The (B) tackifier resin used in the examples is E865-NT (softening temperature: 160 ° C., manufactured by Arakawa Chemical Co., Ltd.), SK-253NS (softening temperature: 145 ° C., manufactured by Harima Kasei Co., Ltd.), SK. -385NS (softening temperature: 80 ° C., manufactured by Harima Chemicals). Table 1 shows the (B) tackifier resin used in each example and comparative example.

  Tetrahydrofuran gel content is measured by adding 0.15 g of the dried film of the pressure-sensitive adhesive composition to 50 mL of tetrahydrofuran, dissolving with stirring for 16 hours, filtering the solution using filter paper corresponding to JIS P3801, and then filtering the filtrate. 10 mL was collected and dried, and the insoluble matter (gel content) was calculated from the dry mass.

  The method of measuring Mw by GPC of the tetrahydrofuran-dissolved component is as follows: 0.15 g of a dry adhesive film is added to 50 mL of tetrahydrofuran, dissolved with stirring for 16 hours, the solution is filtered, and the filtrate is subjected to gel permeation chromatography (GPC). The polystyrene equivalent weight average molecular weight in the filtrate was calculated.

  The glass transition point (Tg) is obtained by thinly stretching about 5 g of the pressure-sensitive adhesive composition on a glass plate and drying at 25 ° C. for 3 days to obtain a dry film. The dry film is obtained using a differential scanning calorimeter (DSC). It was measured. The measurement conditions were a temperature rising rate: 20 ° C./min, a temperature range: −100 ° C. to + 160 ° C., a sample amount: 5 to 10 mg, and measurement was performed under a nitrogen atmosphere. In the analysis, the intermediate temperature between the start point and the end point of the inflection of the differential curve of the obtained differential scanning calorimetry was defined as Tg.

Measurement of the volatile organic compound (VOC) by the Tedlar bag method is to prepare a pressure-sensitive adhesive processing sample, and apply the pressure-sensitive adhesive to the release paper so that the application area is 125 g / m ² and the application area is 80 cm ² (10 cm × 8 cm). And dried at 100 ° C. for 5 minutes. The dried adhesive film was placed in a SUS container, wrapped in the order of an aluminum wheel and saran wrap, further sealed with a plastic bag, and allowed to stand at 23 ° C. and 50% humidity for 14 days. The measuring method of the volatile organic compound (VOC) was based on the Tedlar bag method.

VOC (tetradecane, phthalate-n-butyl, etc.) is measured by PyGC-MS (pyrolysis gas chromatography mass spectrometry), and the volatilization amount is specified in a sample size of 80 cm ² (10 cm × 8 cm) in a Tedlar bag. The amount of substance generated and generated from this was described as the amount of substance in 80 cm ² .

  An adhesion processed sample used for the adhesion performance test was prepared as follows, and each performance test was performed. The pressure-sensitive adhesive was applied to a release paper using an applicator so that the thickness of the dried coating film was 60 μm, and dried at 100 ° C. for 4 minutes. After the dried pressure-sensitive adhesive and 6 mm urethane foam were bonded together, a pressure-bonding roll having a roll interval of 0.6 mm was passed and pressure-bonded. Then, after curing for 3 days under the conditions of 23 ° C. and humidity 65% RH, each adhesion performance test was performed.

  A 90 ° peel strength test according to JIS Z 0237 was performed. An adhesion processed sample having a width of 25 mm and a length of 180 mm was attached to a polypropylene (PP) resin plate, and a 2 kg roller was reciprocated once for pressure bonding. After leaving still for 20 minutes under the conditions of 23 ° C. and humidity 65% RH, the sample was pulled at a pulling speed of 300 mm / min, and the adhesive strength was measured. As a criterion for the 90 ° peel strength test, those with 3.0 N / 25 mm or more were judged good, and those with less than 3.0 N / 25 mm were judged as bad.

  The softening point test, which is one of the heat resistances of the adhesive, was carried out by the following method with reference to the holding power test of JIS Z0237. A 25 mm × 25 mm area of the pressure-sensitive adhesive surface of a pressure-sensitive adhesive sample having a width of 25 mm and a length of 60 mm was attached to a polypropylene (PP) resin plate and subjected to one-time reciprocating pressing with a 2 kg roller to obtain a test specimen. After standing for 15 minutes under the conditions of 23 ° C. and humidity 65% RH, one end of the test specimen is fixed and installed so that the test specimen hangs vertically, and a 310 g weight is attached to the lower end of the test specimen. After holding for 15 minutes, the temperature was raised at a rate of 3 ° C / 5 minutes, and the temperature when the sample dropped was measured. The criterion for the softening point (heat resistance) was that heat resistance was 70 ° C. or higher, and less than 70 ° C. was defective.

  The constant load peeling test, which is one of the heat resistances of the adhesive, was performed as follows. A 25 mm × 50 mm area of the pressure-sensitive adhesive surface of a pressure-sensitive adhesive sample having a width of 25 mm and a length of 100 mm was attached to a polypropylene (PP) resin plate, and was subjected to one reciprocal compression with a 2 kg roller as a test specimen. After leaving still for 15 minutes under the conditions of 23 ° C. and humidity 65% RH, the test specimen was fixed, and the test specimen was placed so as to hang at right angles from the polypropylene (PP) resin plate. A weight of 50 g was attached to the lower end of the test body, allowed to stand at 80 ° C., and the time until the sample dropped was measured. The criterion for constant load peeling (heat resistance) was 50 minutes or more as good and less than 50 minutes as bad.

The weight tack test was performed as follows. Under the conditions of 23 ° C. and humidity 65% RH, a weight having a bottom area of 1 cm ² and a weight of 10 g is gently placed on the adhesive surface of the sample placed on a horizontal table. After standing for 3 seconds, the weight was pulled in the vertical direction at a pulling speed of 200 mm / min, and the adhesive strength was measured. The criterion for determining the weight tack was 300 g / cm ² or more as good and less than 300 g / cm ² as bad.

  As shown in Table 1, in Examples 1-7, the adhesion performance tests were all good. On the other hand, since Comparative Example 1 has a large amount of component (c) of 30 parts by mass, the adhesive strength, heat resistance, and tack were insufficient. In Comparative Example 2, since the component (b) was as large as 23 parts by mass, the heat resistance and tack were insufficient. In Comparative Example 3, since the tetrahydrofuran gel content was as high as 85% by mass, adhesiveness, heat resistance, and tack were insufficient. Since Comparative Example 4 had a low tetrahydrofuran gel content of 3% by mass, the heat resistance was insufficient. Since Comparative Example 5 had a polystyrene-reduced average molecular weight as high as 700,000 as measured by gel permeation chromatography (GPC), the heat resistance and tack performance were insufficient. Since Comparative Example 6 had a high glass transition point of −17 ° C., the adhesiveness, heat resistance, and tack were insufficient. In Comparative Example 7, since the softening temperature of the rosin-based tackifying resin was as low as 80 ° C., even if the addition amount was good, the heat resistance of the pressure-sensitive adhesive composition was insufficient. In Comparative Example 8, since the amount of tackifying resin added was large, the heat resistance and tack were insufficient.

  The water-based emulsion-type pressure-sensitive adhesive composition of the present invention has a component such as a foam base material more than the conventional water-based emulsion-type pressure-sensitive adhesive composition by blending each component as described in the best embodiment. An adhesive composition having excellent adhesion to a rough surface, excellent adhesive strength and heat resistance (softening point, constant load peeling), and extremely low volatile organic compound (VOC) was obtained.

  The heat-resistant pressure-sensitive adhesive composition of the present invention is a water-based emulsion-type pressure-sensitive adhesive composition comprising various foams such as urethane foam and polyethylene foam, polyolefin resin films such as PET and PP, and non-woven fabrics such as rayon and polyester. It can be used as a substrate. In addition, it has good adhesion to adherends such as polyolefin resin such as PET and PP, metal, and is useful for automobile interior use, home appliance use and building material use. It can also be used for bonding.

Claims (9)

(A) (a) 65 to 99.9 parts by weight of (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group;
(B) 0.1 to 20 parts by mass of a hydroxyl group-containing monomer;
(C) a copolymer emulsion obtained by emulsion polymerization of 0 to 27 parts by mass of other polymerizable monomers [where (a) + (b) + (c) = 100 parts by mass], and
(B) The softening temperature is 140 to 170 ° C., and 1 to 30 parts by mass of the rosin-based tackifying resin in which the resin is emulsified,
When dissolved in tetrahydrofuran, the gel content remaining as a solid content without being dissolved is 15 to 60% by mass, and when the tetrahydrofuran content is measured by gel permeation chromatography (GPC), the polystyrene content of the tetrahydrofuran dissolved An aqueous emulsion-type pressure-sensitive adhesive composition having a converted weight average molecular weight (Mw) of 50,000 to 500,000.   The water-based emulsion-type pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic acid alkyl ester is butyl (meth) acrylate and / or 2-ethylhexyl (meth) acrylate.   The water-based emulsion-type pressure-sensitive adhesive composition according to claim 1, wherein the (b) hydroxyl group-containing monomer is 2-hydroxyethyl (meth) acrylate.   The water-based emulsion-type pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein a glass transition point of the pressure-sensitive adhesive composition is -75 to -20 ° C.   The water-based emulsion-type pressure-sensitive adhesive composition according to claim 1, wherein the rosin-based tackifying resin is a solventless type tackifying resin. The total concentration of formaldehyde, acetaldehyde, toluene, ethylbenzene, xylene, styrene and tetradecane in a volatile organic compound (VOC) is 4.5 μg / 80 cm ² or less when the pressure-sensitive adhesive composition is measured by a Tedlar bag method. The water-based emulsion-type pressure-sensitive adhesive composition according to any one of 1 to 5.   The adhesive tape or adhesive sheet formed by apply | coating the water-system emulsion type adhesive composition of any one of Claims 1-6 to the single side | surface or both surfaces of a foam base material.   The adhesive tape or adhesive sheet formed by apply | coating the water-system emulsion type adhesive composition of any one of Claims 1-6 to the single side | surface or both surfaces of a resin-made base material.   The adhesive tape or adhesive sheet formed by apply | coating the water-system emulsion type adhesive composition of any one of Claims 1-6 to the single side | surface or both surfaces of a fibrous base material.