Chloroprene polymer latex-containing adhesive composition

Abstract

[Problem] To develop a chloroprene polymer latex adhesive composition without undergoing a complicated process, the chloroprene polymer latex adhesive composition being intended to be used as an interior material for automobiles, being excellent in both of the adhesiveness to a non-polar material such as an olefin and heat creep resistance and having satisfactory storage stability. [Solution] Provided is an adhesive composition containing a chloroprene polymer latex, the adhesive composition being characterized by comprising a chloroprene polymer latex (A), an adhesiveness-imparting agent (B) and a chlorinated polyolefin resin (C), in which the content of a gel component of a chloroprene polymer in the chloroprene polymer latex (A) is more than 0% by mass and is equal to or less than 50% by mass, the softening point of the adhesiveness-imparting agent (B) is 85°C or higher, the softening point of the chlorinated polyolefin resin (C) is lower than 80°C, the content of the adhesiveness-imparting agent (B) is 5 parts by mass to 30 parts by mass exclusive relative to 100 parts by mass of solid content of the chloroprene polymer latex (A), the content of the chlorinated polyolefin resin (C) is 6 parts by mass or more and less than 30 parts by mass relative to 100 parts by mass of the solid content of the chloroprene polymer latex (A), and no crosslinking agent is contained.

Description

Technical Field

[0001] The present invention relates to a latex adhesive composition, an adhesive layer, and a laminate using a chloroprene polymer latex.

Background Art

[0002] A chloroprene polymer is polychloroprene obtained by emulsion polymerization of 2-chloro-1,3-butadiene, and exhibits high cohesive strength and crystallinity. Chloroprene polymers are mainly produced by emulsion polymerization, and a chloroprene polymer latex in which polymer particles after polymerization are dispersed in water can be applied to a substrate without dissolving the chloroprene polymer in a solvent, and is used as an environmentally friendly water-based adhesive for furniture, shoes, civil engineering, wet suits, etc.

[0003] In recent years, due to the strengthening of global regulations on volatile organic compounds, the switch from solvent-based adhesives to water-based adhesives with a lower environmental impact has been promoted, and the demand for water-based adhesives of chloroprene polymer latex has been increasing. However, since polyolefin resins used as automotive interior materials such as sheets and instrument panels are non-polar materials, there is a large polarity difference from chloroprene polymers, and it is extremely difficult to exhibit sufficient adhesive strength to polyolefin resins. Examples of polyolefin resins include polyethylene resins and polypropylene resins.

[0004] Polyolefin resins are inexpensive and excellent in lightness, and are used in a wide range of fields including automotive interiors and building interiors for improving fuel efficiency. If this polyolefin resin cannot be adhered, restrictions occur in the product manufacturing process, and thus problems have been solved by surface modification of the adhesive surface by oxidation treatment or chemical treatment, use of appropriate primers and crosslinking agents, etc.

[0005] In recent years, there has been a demand for water-based adhesives that do not require the aforementioned surface treatment, from the perspective of reducing the cost associated with surface treatment. Furthermore, in automotive interior materials, if the interior temperature rises to high temperatures (e.g., 80°C) during the summer, insufficient heat resistance of the adhesive can cause creep, such as lifting and peeling. In fields where such heat-creep resistance is required, water-based adhesives that fully satisfy the required characteristics have not yet been developed. Therefore, in order to address these demands, improvements to the adhesion of chloroprene polymer latex adhesives to polyolefin resins are being investigated.

[0006] Patent Document 1 discloses a polychloroprene polymer latex adhesive composition characterized by containing a copolymer of chloroprene monomer and ethylenically unsaturated carboxylic acid, a carboxy-modified chloroprene polymer latex (a) containing polyvinyl alcohol as a nonionic surfactant, a chlorinated polyolefin resin emulsion (b), and zinc oxide (c).

[0007] Patent Document 2 discloses a chloroprene rubber latex adhesive composition characterized by containing a chloroprene rubber latex synthesized using a rosinate-based surfactant (a), a chloroprene rubber latex having a carboxyl group or a hydroxyl group in the molecule (b), and a carbodiimide compound.

[0008] Patent Document 3 discloses a chloroprene-based latex adhesive composition characterized by comprising 100 parts by weight of solids of chloroprene polymer latex (A) with a gel content of 40% or less, 1 to 100 parts by weight of tackifying resin emulsion (B), 1 to 20 parts by weight of chlorinated polyolefin resin emulsion (C), and 0.1 to 10 parts by weight of titanium chelate (D).

[0009] Patent Document 4 discloses a chloroprene rubber latex adhesive composition containing a carboxy-modified chloroprene copolymer latex (A) containing a copolymer of chloroprene monomer and ethylenically unsaturated carboxylic acid and polyvinyl alcohol, a chloroprene polymer latex (B) containing a chloroprene homopolymer or a copolymer of chloroprene monomer and another monomer and a metal rosinate salt, and a chlorinated polyolefin resin emulsion (C), wherein the content of the carboxy-modified chloroprene copolymer latex (A) and the chloroprene polymer latex (B) is 80:20 to 20:80 on a solid content basis. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2017-222804 [Patent Document 2] Japanese Patent Publication No. 2011-63672 [Patent Document 3] Japanese Patent Publication No. 2002-275442 [Patent Document 4] International Publication No. 2018 / 043586 [Overview of the project] [Problems that the invention aims to solve]

[0011] Patent Document 1 describes using a chloroprene copolymer latex copolymerized with an ethylenically unsaturated carboxylic acid to improve the adhesion performance of a chloroprene polymer latex adhesive to polyolefin resins. However, this required complicated procedures, such as copolymerizing with an ethylenically unsaturated carboxylic acid.

[0012] Furthermore, while Patent Document 2 describes a method that improves adhesion and heat resistance by blending two types of chloroprene polymer latex having specific gel component content and further incorporating a carbodiimide compound as a crosslinking agent, it suffers from poor storage stability due to the inclusion of a crosslinking agent.

[0013] Patent Document 3 describes how titanium chelate is used as a crosslinking agent to improve olefin adhesion resistance and heat creep resistance in chloroprene polymer latex with a specific gel component content below a certain level. However, the inclusion of a crosslinking agent resulted in poor storage stability and a complicated compounding process.

[0014] Patent Document 4 describes how carboxy-modified chloroprene copolymer latex and chloroprene polymer latex are blended in a specific ratio to improve adhesive strength and heat creep resistance. However, because the carboxy-modified chloroprene copolymer latex must be produced by copolymerization and then blended with chloroprene polymer latex, the process itself and the blending work are complicated.

[0015] Therefore, the object of the present invention is to develop a chloroprene polymer latex adhesive composition for automotive interior materials that has excellent adhesion to nonpolar materials such as olefins, good heat creep resistance, and good storage stability, without requiring complicated processes such as compounding, blending, or copolymerization of plasticizers. [Means for solving the problem]

[0016] In order to solve the above problems, the present inventors conducted various studies and found that the above problems can be solved by adding a tackifier (B) and a chlorinated polyolefin resin (C) to a chloroprene polymer latex (A) having a specific gel component content.

[0017] In other words, the present invention relates to a chloroprene polymer latex-containing adhesive composition and adhesive layer comprising the following chloroprene polymer latex (A), tackifier (B), and chlorinated polyolefin resin (C).

[0018] In other words, the present invention has the following configuration. [1] A chloroprene polymer latex (A), a tackifier (B), and a chlorinated polyolefin resin (C), wherein the gel component content of the chloroprene polymer in the chloroprene polymer latex (A) is greater than 0% by mass and less than or equal to 50% by mass, at least one of the tackifiers (B) has a softening point of 85°C or higher, and the chlorinated polyolefin resin (C) has a softening point of less than 80°C. With respect to 100 parts by mass of the solid content of the chloroprene polymer latex (A), the amount of the tackifier (B) is more than 5 parts by mass but less than 30 parts by mass. The chlorinated polyolefin resin (C) is present in an amount of 6 parts by mass or more and less than 30 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer latex (A), A chloroprene polymer latex-containing adhesive composition characterized by not containing a crosslinking agent. [2] The chloroprene polymer latex-containing adhesive composition of [1], wherein the chloroprene polymer is a chloroprene homopolymer or a copolymer containing at least chloroprene and 2,3-dichloro-1,3-butadiene. [3] The chloroprene polymer latex-containing adhesive composition of [1] or [2], wherein the tackifier (B) comprises at least one of rosin resin, rosin ester resin, terpene phenol resin, and alicyclic petroleum resin. [4] The chloroprene polymer latex-containing adhesive composition of [1] to [3], wherein the softening point of the tackifier (B) is 85°C or higher and 250°C or lower. [5] A chloroprene polymer latex-containing adhesive composition of [1] to [4], further comprising a metal oxide or hydroxide. [6] A chloroprene polymer latex-containing adhesive composition of [1] to [5], further comprising a thickening agent. An adhesive layer comprising the chloroprene polymer latex-containing adhesive compositions of [7][1] to [6]. A laminate formed by laminating two adherends via the chloroprene polymer latex-containing adhesive compositions of [8][1] to [6]. [9] A laminate of [8] wherein at least one of the adherends is a foamed organic material.

[10] The laminate according to [9], wherein the foamed organic material of the laminate is any one of polypropylene, polyethylene, and polyurethane.

Advantages of the Invention

[0019] The chloroprene polymer latex-containing adhesive composition of the present invention has high adhesive strength, excellent heat-resistant creep properties, and particularly excellent adhesiveness to non-polar materials. Therefore, the chloroprene polymer latex adhesive composition of the present invention is suitable as an adhesive for adherends made of materials such as polyolefin resins and polyurethanes. In addition, the chloroprene polymer latex of the present invention can be suitably used in applications exposed to high temperatures (e.g., 80 °C), such as adhesives in automotive interior materials, without causing creep.

Embodiments for Carrying out the Invention

[0020] Hereinafter, embodiments of the present invention will be specifically described. The chloroprene polymer latex-containing adhesive composition of this embodiment contains [1] a chloroprene polymer latex (A), a tackifier (B), and a chlorinated polyolefin resin (C).

[0021] <Chloroprene Polymer Latex (A)> The chloroprene polymer latex (A) is one in which particles of a chloroprene polymer are dispersed in water.

[0022] The chloroprene polymer in the chloroprene polymer latex (A) is a homopolymer of 2-chloro-1,3-butadiene (hereinafter also referred to as 'chloroprene') or a copolymer containing chloroprene as at least a monomer component.

[0023] Chloroprene polymer The chloroprene polymer constituting the chloroprene polymer latex (A) of this embodiment is a homopolymer or copolymer of chloroprene. In the case of a copolymer, it may be a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, a copolymer of chloroprene and another copolymerizable monomer, or a copolymer of chloroprene, 2,3-dichloro-1,3-butadiene and another copolymerizable monomer. Furthermore, two or more units derived from the other copolymerizable monomer may be copolymerized as needed. Preferably, the chloroprene polymer is a polymer containing more than 50 mol% of chloroprene as a monomer component.

[0024] The chloroprene polymer is preferably a homopolymer of chloroprene or a copolymer of at least chloroprene and 2,3-dichloro-1,3-butadiene as monomer components, and more preferably a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene. Other copolymerizable monomers that may be included in the chloroprene copolymer constituting the chloroprene polymer latex (A) of this embodiment are not particularly limited as long as they are monomers that can copolymerize with at least one of the above-mentioned chloroprene and 2,3-dichloro-1,3-butadiene. Specifically, examples include 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and the like.

[0025] The chloroprene polymer constituting the chloroprene polymer latex (A) of this embodiment is composed of chloroprene, 2,3-dichloro-1,3-butadiene, and other copolymerizable monomer components, with a total of 100 parts by mass of these components. The units derived from the chloroprene are preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 88 parts by mass or more. The upper limit is preferably 100 parts by mass or less. Furthermore, if units derived from 2,3-dichloro-1,3-butadiene are included, they should be present in an amount greater than 0 parts by mass, with an upper limit of preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass. Other copolymerizable monomers are preferably included in an amount of 5 parts by mass or less.

[0026] Latex composed of chloroprene polymers whose monomer component composition falls within the aforementioned range is preferable because the crystallization of the chloroprene polymer is suppressed, thereby imparting tack, and thus increasing the adhesive strength of the adhesive layer.

[0027] The average particle diameter of the chloroprene polymer particles constituting the latex is preferably 50 nm or more, more preferably 70 nm or more, and even more preferably 90 nm or more. The upper limit of the average particle diameter is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 210 nm or less.

[0028] Latex with an average particle size within the aforementioned range is preferable because it has low emulsion stability of the latex particles, and the emulsion system breaks down quickly during bonding, resulting in the emergence of adhesive strength, thus increasing the adhesive strength of the adhesive layer.

[0029] The content of the gel component of the chloroprene polymer in the chloroprene polymer latex (A) is preferably greater than 0% by mass, preferably 10% by mass or more, and more preferably 20% by mass. The upper limit is 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less.

[0030] When the gel component content is within the aforementioned range, the latex containing chloroprene polymer exhibits excellent heat creep resistance and high adhesion because a cross-linked structure is formed within the chloroprene polymer. For these reasons, it is desirable in this embodiment that the chloroprene polymer latex-containing adhesive composition is substantially free of crosslinking agents. Generally, examples of crosslinking agents include polyisocyanate compounds, carbodiimide compounds, and oxazoline compounds, but the inclusion of crosslinking agents can reduce the storage stability of the composition. Chloroprene polymer latex (A) may be a combination of two or more types.

[0031] The method for obtaining the chloroprene polymer latex (A) is not limited, but in one embodiment, chloroprene alone, or chloroprene and 2,3-dichloro-1,3-butadiene, and optionally other copolymerizable monomers, may be emulsion polymerized in the presence of an emulsifier, preferably a metal rosinate salt, and optionally a polymerization initiator and a chain transfer agent. When a predetermined polymerization conversion rate is reached, a polymerization inhibitor may be added to stop the polymerization.

[0032] The type of emulsifier used in the chloroprene polymer latex (A) of this embodiment is not particularly limited, but examples include anionic emulsifiers and nonionic emulsifiers, with anionic emulsifiers being particularly preferred. These emulsifiers may be used individually or in combination of two or more.

[0033] The types of anionic emulsifiers are not particularly limited, but examples include alkali metal salts of rosinic acid, dodecylbenzenesulfonates (such as sodium dodecylbenzenesulfonate and triethanolamine dodecylbenzenesulfonate), diphenyl ethersulfonates (such as sodium diphenyl ethersulfonate and ammonium diphenyl ethersulfonate), naphthalenesulfonates (such as sodium β-naphthalenesulfonic acid formaldehyde condensate), and alkali metal salts of fatty acids (such as potassium laurate). Alkali metal salts of disproportionated rosinic acid are particularly preferred.

[0034] The type of rosin acid is not particularly limited, but examples include gum rosin, wood rosin, tall rosin, disproportionated rosin obtained by disproportionation reaction of these, and purified rosin, with disproportionated rosin being preferred. Alkali metal salts are usually used, preferably sodium salts and / or potassium salts. Alternatively, rosin acid and alkali metal hydroxides may be added separately to form alkali metal salts of rosin acid.

[0035] The type of nonionic emulsifier is not particularly limited, but examples include partially saponified polyvinyl alcohol, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene lauryl ether, with partially saponified polyvinyl alcohol being particularly preferred. These emulsifiers may be used individually or in combination of two or more. In this embodiment, it is preferable to include a metal rosinate salt as an emulsifier.

[0036] If a metal rosinate salt is included, its content is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the starting monomer. The upper limit of the metal rosinate salt content is 8 parts by mass or less, more preferably 6.5 parts by mass or less, and even more preferably 5.0 parts by mass or less. By setting the metal rosinate salt content within the above range, polymerization stability during emulsion polymerization can be improved, the number of micelles formed is appropriate, which suppresses heat generation in the initial stages of polymerization, and the viscosity during polymerization can be kept within a predetermined range. The metal rosinate salt content is based on the starting monomer, but is synonymous with the solid content of the polymer and corresponds to the content in chloroprene polymer latex (A).

[0037] The solid content concentration of the chloroprene polymer latex (A) is preferably 35% by mass or more, more preferably 40% by mass or more, and even more preferably 45% by mass or more. The upper limit of the solid content concentration of the chloroprene polymer latex (A) is preferably 65% ​​by mass or less, and more preferably 60% by mass or less. If the solids content concentration is within the above range, it is possible to reduce the drying time of chloroprene polymer latex (A) and reduce the load on the drying equipment. Furthermore, if the solids content concentration is within the above range, it is easier to maintain the colloidal stability of chloroprene polymer latex (A), and the generation of aggregates can be minimized. The dispersion medium is usually water.

[0038] In this embodiment, the solid content refers to the components remaining after removing solvents, volatile components, and other components that volatilize under the solid content measurement conditions from the latex or emulsion. The solid content of chloroprene polymer latex (A) includes not only the chloroprene polymer but also emulsifiers used during production, such as metal rosinate salts.

[0039] <Tackifier (B)> Tackifier (B) is added to improve the adhesion of the chloroprene polymer latex-containing adhesive composition and the contact properties of the chloroprene polymer. In particular, it can improve contact properties when polyolefin is used as the adherend.

[0040] The tackifier (B) is more than 5 parts by mass, preferably 10 parts by mass or more, and more preferably 18 parts by mass or more, per 100 parts by mass of the solid content of the chloroprene polymer latex (A). The upper limit is less than 30 parts by mass, preferably 25 parts by mass or less, and more preferably 22 parts by mass or less. By including the tackifier (B) within the above range, the adhesion of the chloroprene polymer latex-containing adhesive composition and the contact adhesion of the chloroprene polymer can be improved, and the heat creep resistance with respect to the adherend can be improved.

[0041] The softening point of at least one of the tackifiers (B) is 85°C or higher, preferably 90°C or higher. The upper limit of the softening point of the tackifier (B) is not particularly limited, but is preferably 250°C or lower, and more preferably 200°C or lower. By having a softening point within the above range of the tackifier (B), the adhesion of the chloroprene polymer latex-containing adhesive composition can be maintained at high temperatures, and the heat creep resistance can be improved. The tackifier (B) may be used alone or in combination of two or more types. When using two or more types of tackifiers (B), at least one of them must have a softening point of 85°C or higher. When using two or more types, it is preferable that all of the tackifiers (B) have a softening point of 85°C or higher.

[0042] Furthermore, when the tackifier (B) is used in an emulsion or solution as described later, the above amount is the amount of solids excluding the solvent, etc. The type of tackifier (B) is not particularly limited, but examples include rosin resin or rosin ester resin, terpene phenol resin, aliphatic petroleum resin, alicyclic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, hydrogenated petroleum resins, alkylphenol resin, and others. Examples of rosin resins and rosin ester resins include gum rosin, tall rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated versions thereof, and esterified versions thereof. Examples of terpene phenol resins include hydrogenated terpene phenol resins. Preferably, the tackifier (B) contains at least one of rosin resin, terpene phenol resin, and alicyclic petroleum resin, and more preferably at least one selected from rosin ester resin and terpene phenol resin. Note that the rosin resin and rosin ester resin used in the tackifier (B) are different from and do not constitute alkali metal salts of rosin acid.

[0043] While it is common practice to add the tackifier (B) by mixing an emulsion of the tackifier (B) with the chloroprene polymer latex (A), the tackifier (B) itself may also be added during the manufacturing process of the chloroprene polymer latex (A). This method of addition is effective for types of tackifier (B) for which an emulsion is not commercially available.

[0044] Commercially available tackifiers (B) that can be used in this embodiment include the polymerized rosin emulsion Super Ester® E-900-NT manufactured by Arakawa Chemical Industries, Ltd., the rosin emulsion E-720W manufactured by Arakawa Chemical Industries, Ltd. of Taiwan, and Hariestar SK-218NS, Hariestar SK-323NS, and Hariestar SK-508H manufactured by Harima Chemicals Ltd., as well as the terpene phenol resin emulsions Tamanol® E-100, Tamanol® E-200NT, Tamanol® E-102A manufactured by Arakawa Chemical Industries, Ltd., and TR-602 manufactured by BASF. In addition, solid tackifiers (B) include the alicyclic petroleum resin Alcon® M-135 manufactured by Arakawa Chemical Industries, Ltd.

[0045] <Chlorinated polyolefin resin (C)> Chlorinated polyolefin resin (C) is a resin obtained by chlorinating polyolefin. Chlorinated polyolefin resin (C) is a component that contributes to imparting adhesion to nonpolar materials such as polyolefin resins to chloroprene polymer latex-containing adhesive compositions.

[0046] The content of chlorinated polyolefin resin (C) is 6 parts by mass or more, preferably 8 parts by mass or more, and more preferably 10 parts by mass or more, per 100 parts by mass of solids of chloroprene polymer latex (A). The upper limit of the content is less than 30 parts by mass, preferably 25 parts by mass or less, and more preferably 22 parts by mass or less.

[0047] By adding chlorinated polyolefin resin (C), good adhesion to polyolefin resin can be enhanced, and if the numerical value is within the aforementioned range, high heat creep resistance can be maintained, and it is also cost-effective. Note that, as will be described later, when chlorinated polyolefin resin (C) is used in emulsions or solutions, the aforementioned amount is the amount of solids excluding solvents, volatile components, and other components that volatilize under the solids content measurement conditions, and if a surfactant is included, the amount including the surfactant is also included in the solids content.

[0048] The softening point of the chlorinated polyolefin resin (C) is less than 80°C, preferably 75°C or lower, and more preferably 70°C or lower. The lower limit of the softening point of the chlorinated polyolefin resin (C) is preferably 40°C or higher. By including a chlorinated polyolefin resin (C) with a softening point within the above range, the chlorinated polyolefin resin (C) becomes compatible with the chloroprene polymer during drying, improving adhesion to the polypropylene resin.

[0049] As a raw material for the chlorinated polyolefin resin (C), any known raw material for chlorinated polyolefin resins can be freely selected and used, as long as it does not impair the effects of this embodiment. Examples include crystalline polypropylene, amorphous polypropylene, polybutene-1, low-density or high-density polyethylene, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer.

[0050] The chlorinated polyolefin resin (C) is preferably an acid-modified chlorinated polyolefin resin obtained by graft polymerization of at least one monomer selected from α,β-unsaturated carboxylic acids and their anhydrides. Examples of α,β-unsaturated carboxylic acids and their anhydrides used here include maleic acid, itaconic acid, citraconic acid, fumaric acid, mesaconic acid, aconitic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, and aconitic anhydride. Acid modification of the chlorinated polyolefin resin (C) allows for crosslinking between polyvalent metal ions and carboxyl groups when metal oxides such as zinc oxide or magnesium oxide are incorporated into the adhesive, thereby improving adhesive properties such as heat creep resistance and solvent resistance.

[0051] The chlorine content of the chlorinated polyolefin resin (C) is not particularly limited, but is preferably 10% by mass or more, more preferably 16% by mass or more, and more preferably 18% by mass or more. The upper limit is preferably 40% by mass or less, more preferably 22% by mass or less, and even more preferably 21% by mass or less. By setting the chlorine content of the chlorinated polyolefin resin (C) within the above range, the adhesion to nonpolar materials, especially polyolefin resins, is improved. In another embodiment of this model, the adhesive composition contains chloroprene polymer latex (A), a tackifier (B), and a chlorinated polyolefin resin (C), wherein the softening point of the tackifier (B) is 5°C or higher than the softening point of the chlorinated polyolefin resin (C). In this embodiment, the gel component content of the chloroprene polymer latex (A) is not particularly limited, and the softening points of the tackifier (B) and the chlorinated polyolefin resin (C) are not particularly limited as long as there is a difference of 5°C or more in their softening points, although those exemplified above are preferred.

[0052] The chlorinated polyolefin resin (C) can be mixed with chloroprene polymer latex (A) and tackifier (B), but its form of use is not particularly limited as long as it is mixed with these, although typically an emulsion dispersed in a dispersion medium is used. The emulsion may also contain a surfactant for emulsification as appropriate. The surfactant used in the emulsion of the chlorinated polyolefin resin (C) is not particularly limited as long as it does not impair the effects of this embodiment, and examples include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. In this technology, it is preferable to use a nonionic surfactant from the viewpoint of storage stability of the adhesive composition.

[0053] Examples of commercially available products that can be used as chlorinated polyolefin resin (C) include Nippon Paper Industries Co., Ltd.'s water-based chlorinated polyolefin Supercron (registered trademark) E-480T.

[0054] The solid content concentration of the chlorinated polyolefin resin (C) emulsion is preferably 15% by mass or more, and more preferably 20% by mass or more. The upper limit is 60% by mass or less, and more preferably 45% by mass or less. If the solid content concentration is within the above range, the viscosity is appropriate and it is easily mixed with chloroprene polymer latex (A) and tackifier (B). The dispersion medium is usually water. Additives such as ethylene glycol and ethanol, which are water-compatible solvents, may be included. Chlorinated polyolefin resin (C) may be a combination of two or more types.

[0055] <Metal oxides or hydroxides> The chloroprene polymer latex-containing adhesive composition according to this embodiment may include, in addition to the chloroprene polymer latex (A), the tackifier (B), and the chlorinated polyolefin resin (C), a metal oxide or hydroxide.

[0056] The metal oxide or hydroxide is preferably a polyvalent metal oxide or hydroxide, and more preferably a metal oxide or hydroxide of a metal other than a divalent alkaline earth metal. Metal oxides or hydroxides are added to adhesive compositions to improve their adhesion and heat creep resistance. In particular, the presence of carboxyl groups in the adhesive composition can further improve heat creep resistance due to crosslinking between polyvalent metal ions and carboxyl groups. Furthermore, it can improve adhesion when polyolefins are used as the adherend.

[0057] The metal oxide or hydroxide is preferably used in an amount of 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, based on the solid content of chloroprene polymer latex (A) per 100 parts by mass. The upper limit is 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less. Adding the metal oxide or hydroxide can improve the heat creep resistance. Furthermore, adding it within the above range can prevent a decrease in initial adhesive strength and contact adhesion, and can also reduce costs.

[0058] The metal oxide or hydroxide used in this embodiment is not particularly limited, but specifically, examples include zinc oxide, magnesium oxide, zinc hydroxide, magnesium hydroxide, etc., and more preferably zinc oxide or magnesium oxide. Two or more of these metal oxides can also be used in combination. Of these, zinc oxide is preferred because it readily forms ion crosslinks with the chloroprene polymer.

[0059] Furthermore, in order to quickly mix with water-based adhesives, it is preferable to add the product in a dispersed form in water. A commercially available product that can be used in this embodiment is AZ-SW manufactured by Osaki Industries Co., Ltd.

[0060] The chloroprene polymer latex-containing adhesive composition of this embodiment is manufactured by mixing chloroprene polymer latex (A), a tackifier (B), and a chlorinated polyolefin resin (C) with metal oxides or hydroxides as needed.

[0061] There are no particular restrictions on the mixing method, but any known method such as a mixer can be used. The chloroprene polymer latex-containing adhesive composition of this embodiment may optionally contain fillers, pigments, colorants, wetting agents, defoaming agents, thickeners, and the like. In the composition of this embodiment, a form containing a thickening agent is also desirable. As the thickening agent, the SN Thickener series (manufactured by Sunopco, Inc.), which contains urethane-modified polyether, can be used.

[0062] The resulting chloroprene polymer latex-containing adhesive composition is adjusted to the appropriate solid content concentration and viscosity depending on the purpose. Known methods such as evaporation or addition of water are employed for adjustment.

[0063] In this embodiment, an adhesive layer is formed from the chloroprene polymer latex-containing adhesive composition. The method for manufacturing the adhesive layer is not limited, but it can be manufactured by applying the adhesive composition to the surface of the substrate on the adherend side, drying it at a temperature of 40°C or higher for 3 minutes or more, and then heating the other adherend at a temperature of 130°C or higher for 1 minute or more to bond them together. The substrate is a material among the adherends that has sufficient strength and rigidity, such as resin or metal. Examples of resins include polyethylene, polypropylene, and ABS resin, and examples of metals include iron and aluminum. The drying temperature is preferably 60°C or higher, and more preferably 80°C or higher.

[0064] The adherend is not particularly limited as long as it can be coated, and it can be used for bonding foams, sheets, films, canvas, glass, etc. It exhibits particularly high adhesion to polyolefins and polyurethanes, which are difficult to bond, making it effective in cases where at least one of the adherends falls into these categories. Of these, the composition of this embodiment is highly effective when at least one of the adherends is a laminate made of foamed organic material, and is even more effective when the foamed organic material is one of the poorly adhering materials: polypropylene, polyethylene, or polyurethane.

[0065] The application method is not particularly limited, and known methods such as brush application, spatula application, spraying, dipping, and coating can be used. The thickness of the adhesive layer is not particularly limited as long as it maintains adhesive strength, and is usually around 20-100 μm after drying, but is not particularly limited.

[0066] Furthermore, in this embodiment, the laminate is formed by stacking adherends via the adhesive layer. In other words, the laminate according to this embodiment is formed by laminating two adherends via the chloroprene polymer latex-containing adhesive composition, wherein at least one of the adherends is a polyolefin. It can be used without particular limitation even if both adherends are made of the same material. Furthermore, the method of manufacturing such a laminate is not particularly limited; an adhesive layer may be provided on one or both adherends beforehand, and then the adherends may be laminated and bonded. To ensure strong adhesion, the laminate may be pressurized, and the pressurization may be applied to the entire laminate or only to the portion with the adhesive layer. The pressurization method is not particularly limited, and the pressure is also not particularly limited as long as it is not so high as to cause significant deformation of the adhesive layer. [Examples]

[0067] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples. The physical properties shown in the examples and comparative examples were measured under the following conditions and measurement methods.

[0068] [Measurement method] 1) Solid content concentration The solid content concentration of the emulsion of chloroprene polymer latex (A), tackifier (B), and chlorinated polyolefin resin (C) is calculated by drying 1 g of the emulsion of chloroprene polymer latex (A), tackifier (B), or chlorinated polyolefin resin (C) in an air-heated state (141°C for 30 minutes) on a 39 mm diameter aluminum dish to obtain only the solid content, and then calculating the solid content from the mass before drying and the mass after drying. Solid content concentration (mass%) = [(mass of latex and emulsion after drying at 141°C for 30 minutes) / (mass of latex and emulsion before drying)] × 100

[0069] 2) Polymerization conversion rate of chloroprene polymers Approximately 1 g of chloroprene polymer latex (A) was precisely weighed into an aluminum dish, heated and dried in an oven at 141°C for 30 minutes, then allowed to cool to room temperature in a desiccator. The mass was then measured to determine the mass of the non-volatile components. The polymerization conversion rate was calculated by assuming that all monomers such as chloroprene and 2,3-dichloro-1,3-butadiene polymerized to become non-volatile components, with the theoretical non-volatile component ratio of the reaction solution being 100%. The polymerization conversion rate was determined according to equation (1). Polymerization conversion rate [%] = [(amount of polymer produced / amount of monomer added)] × 100 ... (1) When calculating the amount of polymer produced by chloroprene polymer latex (A), the amount was calculated by subtracting the content of tackifiers, surfactants (other than those used during the polymerization of chloroprene polymer latex (A)), vulcanization accelerators, metal oxides such as zinc oxide dispersions, acid acceptors, antioxidants, fillers, pigments, colorants, wetting agents, defoamers, thickeners, etc., from the mass of nonvolatile components.

[0070] 3) Gel component content 1 g of chloroprene polymer latex (A) (moisture content: 35-65% by mass) is added dropwise to 100 ml of tetrahydrofuran (hereinafter also referred to as "THF"), shaken for 12 hours, and then the supernatant dissolved phase is separated by centrifugation. The THF is evaporated to dryness at 100°C for 1 hour, and the mass of the dry substance is measured. Since the mass of this dry substance is the mass of the tetrahydrofuran-soluble component of the chloroprene polymer, the mass of the tetrahydrofuran-soluble component is subtracted from the mass of the chloroprene polymer to obtain the mass of the gel, and the gel component content in the chloroprene polymer is calculated. Note that the mass of the chloroprene polymer is approximately the same as the mass of the solid content of chloroprene polymer latex (A), so that value can be used. Gel component content (%) = ((Chloroprene polymer mass (g)) - (Dry mass (g))) ÷ (Chloroprene polymer mass) × 100

[0071] 4) Average particle size The average particle size was determined by measuring the z-average particle size using a dynamic light scattering photometer (ZETASIZER® Nano-S, manufactured by Malvern Panalytical Ltd.) with a solution of latex or emulsion diluted to 0.01–0.1 mass% in pure water.

[0072] 5) Softening point 1 g of tackifier (B) or chlorinated polyolefin resin (C) was added to 100 mL of tetrahydrofuran and dissolved by shaking for 10 hours in a Yamato Scientific Co., Ltd. shaker (SA300). The dissolved solution, after shaking, was added dropwise to 500 mL of methanol. The resulting solidified material was filtered through an 80-mesh stainless steel mesh and dried overnight in a desiccator. The obtained dried solidified material was measured using the ring-sphere method in accordance with JIS K2207-1996. The sample was melted at a low temperature to prevent the formation of air bubbles, and after melting, the sample was filled into a ring that had been preheated to an appropriate temperature, and the softening point was measured in a glycerin bath using an automated softening point evaluation device.

[0073] 6) Chlorine content The chlorine content in chlorinated polyolefin (C) was quantified using the oxygen flask combustion method and silver nitrate titration method in accordance with JIS K7229-1995. The chlorine content was determined by dividing the chlorine content by the mass of chlorinated polyolefin (C) and multiplying by 100.

[0074] 7) Adhesive strength A 180° peel test was performed on the test specimens used for the adhesive strength test described later, in accordance with JIS K6854-2-1999. The adhesive strength was measured as the adhesive strength under normal conditions (kN / m). The adhesive strength was measured after curing for one day at 23°C and 60% RH (relative humidity) following application.

[0075] 8) Heat-resistant creep The test specimens for the adhesive strength test, as described later, were cured for one day in a 23°C atmosphere. Then, a load of 100g / 25mm was applied in a 90°C direction, and the peel length after 24 hours was measured to determine the heat-resistant creep.

[0076] 9) Storage stability of adhesive compositions The adhesive composition described later was placed in a 150 mL disposable polypropylene cup, the opening of the cup was sealed with Parafilm, and left to stand at room temperature for 3 days. If the adhesive composition flowed when the cup was tilted, the storage stability was good; if it did not flow, i.e., solidified, the storage stability was considered poor.

[0077] [Preparation of Chloroprene Polymer Latex-Containing Adhesive Compositions] To the chloroprene polymer latex (A) obtained in each preparation example, a tackifier (B), chlorinated polyolefin resin (C), and other additives were added (blended) in the amounts listed in Tables 1 and 2 to prepare chloroprene polymer latex-containing adhesive compositions.

[0078] [Preparation of each test specimen] 1) Test specimens for adhesive strength testing 150g (solids) / m² of polypropylene natural color board (100mm wide x 200mm long x 3mm thick, coated surface 100mm wide x 100mm long) 2 Each chloroprene polymer latex-containing adhesive composition was applied using a 1.5 mm nozzle spray, dried at 80°C for 5 minutes, and then allowed to cool at room temperature for 2.5 minutes. A polypropylene foam (100 mm wide x 200 mm long x 15 mm thick, with the applied surface measuring 100 mm wide x 100 mm long) was dried at 150°C for 2 minutes, bonded to the aforementioned natural-colored polypropylene board, pressed together with a 5 kg hand roller four times, cut into 25 mm wide strips, and used as a test piece for adhesive strength testing.

[0079] Preparation Example 1 [Production of Chloroprene Polymer Latex (A)-1] In a 5L reactor, 1830g of chloroprene monomer, 170g of 2,3-dichloro-1,3-butadiene, 86g of disproportionated rosin (Arakawa Chemical Industries, Ltd., R-600), 1715g of pure water, 22.8g of potassium hydroxide, 5.2g of sodium hydroxide, 1.2g of n-dodecyl mercaptan (molecular weight adjuster), and 10.4g of condensed sodium naphthalene sulfonate solution (product name SN-PW-43 (Sunopco Co., Ltd.)) were charged and emulsified.

[0080] 5.6 g of potassium sulfite was added to this emulsion, followed by 1.2 g of potassium persulfate as a polymerization initiator, and polymerization was carried out at 40°C under a nitrogen gas atmosphere. When the polymerization conversion rate reached 88%, 0.4 g of phenothiazine was immediately added to stop the polymerization. Subsequently, unreacted chloroprene was removed by steam stripping to obtain chloroprene polymer latex (A)-1. The gel component content of the chloroprene polymer in chloroprene polymer latex (A)-1 was 42% by mass, the solid content concentration of chloroprene polymer latex (A)-1 was 50% by mass, and the average particle size was 130 nm.

[0081] Preparation Example 2 [Production of Chloroprene Polymer Latex (A)-2] In a 5L reactor, 2000g of chloroprene monomer, 34.2g of disproportionated rosin (Arakawa Chemical Industries, Ltd., R-600), 1211g of pure water, 21.3g of potassium hydroxide, 3.6g of n-dodecyl mercaptan (molecular weight adjuster), and 24g of condensed sodium naphthalene sulfonate solution (product name SN-PW-43 (Sunopco Corporation)) were charged and emulsified.

[0082] 2.0 g of potassium sulfite was added to this emulsion, followed by 1.0 g of potassium persulfate as a polymerization initiator, and polymerization was carried out at 45°C under a nitrogen gas atmosphere. When the polymerization conversion rate reached 90%, 0.4 g of phenothiazine was immediately added to stop the polymerization. Subsequently, unreacted chloroprene was removed by steam stripping to obtain chloroprene polymer latex (A)-2. The gel component content of the chloroprene polymer in chloroprene polymer latex (A)-2 was 13% by mass, the solid content concentration of chloroprene polymer latex (A)-2 was 58% by mass, and the average particle size was 200 nm.

[0083] Preparation Example 3 [Production of Chloroprene Polymer Latex (A)-3] In a 5L reactor, 1600g of chloroprene, 56g of disproportionated rosin (Arakawa Chemical Industries, Ltd., R-600), 1444g of pure water, 14.4g of sodium hydroxide, 1.8g of n-dodecyl mercaptan (molecular weight adjuster), and 22.6g of condensed sodium naphthalene sulfonate solution (product name SN-PW-43 (Sunopco Co., Ltd.)) were charged and emulsified.

[0084] 4.8 g of potassium sulfite was added to this emulsion, followed by 0.8 g of potassium persulfate as a polymerization initiator, and polymerization was carried out at 15°C under a nitrogen gas atmosphere. When the polymerization conversion rate reached 78%, 0.5 g of phenothiazine was immediately added to stop the polymerization. Subsequently, unreacted chloroprene was removed by steam stripping to obtain chloroprene polymer latex (A)-3. The gel component content of the chloroprene polymer in chloroprene polymer latex (A)-3 was 0% by mass, the solid content concentration of chloroprene polymer latex (A)-3 was 58% by mass, and the average particle size was 130 nm.

[0085] Preparation Example 4 [Production of Chloroprene Polymer Latex (A)-4] In a 5L reactor, 1830g of chloroprene, 170g of 2,3-dichloro-1,3-butadiene, 86g of disproportionated rosin (manufactured by Arakawa Chemical Industries, Ltd., R-600), 1715g of pure water, 22.8g of potassium hydroxide, 5.2g of sodium hydroxide, and 10.4g of condensed sodium naphthalene sulfonate solution (product name SN-PW-43 (manufactured by Sunopco Co., Ltd.)) were charged and emulsified.

[0086] 5.6 g of potassium sulfite was added to this emulsion, followed by 1.2 g of potassium persulfate as a polymerization initiator, and polymerization was carried out at 40°C under a nitrogen atmosphere. When the polymerization conversion rate reached 88%, 0.4 g of phenothiazine was immediately added to stop the polymerization. Subsequently, unreacted chloroprene was removed by steam stripping to obtain chloroprene polymer latex (A)-4. The gel component content of the chloroprene polymer in chloroprene polymer latex (A)-4 was 79% by mass, the solid content concentration of chloroprene polymer latex (A)-4 was 50% by mass, and the average particle size was 130 nm.

[0087] Preparation Example 5 [Production of Chloroprene Polymer Latex (A)-5] In a 5L reactor, 2000g of chloroprene monomer, 34.2g of disproportionated rosin (Arakawa Chemical Industries, Ltd., R-600), 1211g of pure water, 21.3g of potassium hydroxide, 1.0g of n-dodecyl mercaptan (molecular weight adjuster), and 24g of condensed sodium naphthalene sulfonate solution (product name SN-PW-43 (Sunopco Corporation)) were charged and emulsified.

[0088] 2.0 g of potassium sulfite was added to this emulsion, followed by 1.0 g of potassium persulfate as a polymerization initiator, and polymerization was carried out at 45°C under a nitrogen gas atmosphere. When the polymerization conversion rate reached 90%, 0.4 g of phenothiazine was immediately added to stop the polymerization. Subsequently, unreacted chloroprene was removed by steam stripping to obtain chloroprene polymer latex (A)-5. The gel component content of the chloroprene polymer in chloroprene polymer latex (A)-5 was 87% by mass, the solid content concentration of chloroprene polymer latex (A)-5 was 58% by mass, and the average particle size was 200 nm.

[0089] Example 1 A chloroprene polymer latex-containing adhesive composition was obtained by adding 100 parts by mass of chloroprene polymer latex (A)-1 on a solid content basis as chloroprene polymer latex (A), 20 parts by mass of Super Ester E-720W (manufactured by Arakawa Chemical Industries) on a solid content basis as tackifier (B) (solid content concentration: 50% by mass), 20 parts by mass of Superclon® E-480T (manufactured by Nippon Paper Industries) on a solid content basis as an emulsion of chlorinated polyolefin resin (C) (solid content concentration: 30% by mass), 0.5 parts by mass of AZ-SW (manufactured by Osaki Industries Co., Ltd.) on a solid content basis as zinc oxide (solid content concentration: 50% by mass), and 0.3 parts by mass of a 10% by mass diluted solution of SN Thickener 612 (manufactured by Sunopco Co., Ltd.) (solid content concentration: 40% by mass) as a thickener, and then uniformly stirring.

[0090] Examples 2-7, Comparative Examples 1-14 In Example 1, adhesive compositions were prepared by changing the type and amount of chloroprene polymer latex (A), the type and amount of tackifier (B), the amount of chlorinated polyolefin resin (C) emulsion, and the addition of a crosslinking agent, resulting in the adhesive compositions shown in Tables 1 and 2. The results of the adhesive strength evaluation and heat creep resistance test are also shown in Tables 1 and 2.

[0091] Examples are shown in Table 1, and comparative examples are shown in Table 2.

[0092] [Table 1]

[0093] [Table 2]

[0094] The list of reagents is shown in Tables 3-5.

[0095] [Table 3]

[0096] [Table 4]

[0097] [Table 5]

[0098] [Table 6]

[0099] As is clear from Examples 1 to 7 in Table 1, the material contains chloroprene polymer latex (A), tackifier (B), and chlorinated polyolefin resin (C), wherein the gel component content of the chloroprene polymer in the chloroprene polymer latex (A) is greater than 0% by mass and less than 50% by mass, the softening point of at least one of the tackifiers (B) is 85°C or higher, the softening point of the chlorinated polyolefin resin (C) is less than 80°C, and the solid content of the chloroprene polymer latex (A) is 1 / 100% by mass In contrast, a chloroprene polymer latex-containing adhesive composition in which the tackifier (B) is greater than 5 parts by mass but less than 30 parts by mass, the chlorinated polyolefin resin (C) is 6 parts by mass or more but less than 30 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer latex (A), and which does not contain a crosslinking agent, exhibited high adhesive strengths of 0.61 to 1.14 kN / m to both polypropylene boards and polypropylene foams, and showed good heat resistance with a peel length of 10 mm or less during the heat creep test.

[0100] Furthermore, as is clear from Examples 1 to 7, good adhesion to polypropylene and heat resistance are observed regardless of the amount of zinc oxide and thickener added.

[0101] On the other hand, in Comparative Examples 1 to 3 of Table 2, where the content of the gel component of the chloroprene polymer in the chloroprene polymer latex (A) was 0% by mass or more than 50% by mass, the heat creep resistance was insufficient. Furthermore, in Comparative Examples 4 and 5, where the tackifier (B) was present in an amount of 5 parts by mass or less, or 30 parts by mass or more, per 100 parts by mass of solids of chloroprene polymer latex (A), the heat creep resistance was insufficient. Also, in Comparative Examples 6 and 7, where the softening point of the tackifier (B) was less than 85°C, the heat creep resistance was insufficient. Furthermore, in Comparative Examples 8-10, where the chlorinated polyolefin resin (C) was contained in less than 6 parts by mass or 30 parts by mass or more per 100 parts by mass of solids of chloroprene polymer latex (A), the heat creep resistance was insufficient. Also, in Comparative Examples 11-13, where the softening point of the chlorinated polyolefin resin (C) was 80°C or higher, the heat creep resistance was insufficient. Furthermore, in Comparative Example 14, which contained 2 parts by mass of the crosslinking agent WB40-100 per 100 parts by mass of the solid content of the chloroprene polymer latex (A), the storage stability of the adhesive composition was low.

Claims

1. Chloroprene polymer latex (A), Tackifier (B) and It contains chlorinated polyolefin resin (C), The chloroprene polymer latex (A) has a gel component content of chloroprene polymer that is greater than 0% by mass and less than or equal to 50% by mass, the average particle size of the latex particles is 50 nm or more and less than or equal to 500 nm, at least one of the tackifiers (B) has a softening point of 85°C or higher, and the chlorinated polyolefin resin (C) has a softening point of less than 80°C. With respect to 100 parts by mass of the solid content of the chloroprene polymer latex (A), the amount of the tackifier (B) is more than 5 parts by mass but less than 30 parts by mass. The chlorinated polyolefin resin (C) is present in an amount of 6 parts by mass or more and less than 30 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer latex (A). A chloroprene polymer latex-containing adhesive composition characterized by not containing a crosslinking agent and a (meth)acrylic polymer emulsion.

2. The chloroprene polymer latex-containing adhesive composition according to claim 1, wherein the chloroprene polymer is a chloroprene homopolymer or a copolymer containing at least chloroprene and 2,3-dichloro-1,3-butadiene.

3. The chloroprene polymer latex-containing adhesive composition according to claim 1, wherein the tackifier (B) comprises at least one of rosin resin, rosin ester resin, terpene phenol resin, and alicyclic petroleum resin.

4. The chloroprene polymer latex-containing adhesive composition according to claim 1, wherein the softening point of the tackifier (B) is 85°C or higher and 250°C or lower.

5. The chloroprene polymer latex-containing adhesive composition according to claim 1, further comprising a metal oxide or hydroxide.

6. The chloroprene polymer latex-containing adhesive composition according to claim 1, further comprising a thickening agent.

7. An adhesive layer comprising the chloroprene polymer latex-containing adhesive composition according to any one of claims 1 to 6.

8. A laminate comprising two adherends laminated via a chloroprene polymer latex-containing adhesive composition according to any one of claims 1 to 6.

9. The laminate according to claim 8, wherein at least one of the adherends is a foamed organic material.

10. The laminate according to claim 9, wherein the foamed organic material of the laminate is any one of polypropylene, polyethylene, or polyurethane.

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