JP4342706B2 - Polychloroprene latex composition and method for producing the same, and adhesive composition using the same - Google Patents

Description

【００５２】
注１）ＰＶＡ；ＵＭＲ−２０Ｈ、けん化度７９ｍｏｌ％、重合度３８０（ユニチカ社製）
注２）ＰＶＡ；Ｂ−０５、けん化度８８ｍｏｌ％、重合度５５０（電気化学工業社製）
注３）セロゾールＨ６３３：２，６−ジ−ｔ−ブチル−４−メチルフェノールエマルジョン（中京油脂社製）、添加数量は固形分換算
注４）テルペン変性フェノール樹脂エマルジョン；タマノールＥ−１００（荒川化学工業社製）
注５）酸化亜鉛エマルジョン（大崎工業社製）、添加数量は固形分換算
【００５３】
【表２】

【００５４】
【発明の効果】
以上の実施例と比較例の比較より、本発明のポリクロロプレンラテックスは貯蔵安定性、初期接着強度や耐水性に優れていることが明かであり、合板など木材接着、紙材、合成樹脂、鋼板などの接着に特に好適なポリクロロプレンラテックス組成物とその製造方法を提供することが出来る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polychloroprene latex composition effective as an adhesive, a method for producing the same, and an adhesive composition using the same. More specifically, a polychloroprene latex composition suitable as a water-based contact adhesive that has excellent initial adhesive strength, normal adhesive strength, adhesive performance such as adhesive water resistance, and good latex storage stability, and a production method thereof, and The present invention relates to an adhesive composition using
[0002]
[Prior art]
Conventionally, the solvent type is the mainstream of adhesives based on polychloroprene. However, in recent years, solvent-based adhesives have been increasingly required to be solvent-free due to problems such as hygiene, fire hazard, and environmental pollution caused by organic solvents during manufacture and use.
[0003]
As a method for removing the solvent, it is considered effective to replace the solvent-type adhesive with a latex adhesive, and studies on latex adhesives using various polymers have been actively conducted.
[0004]
In particular, the polychloroprene latex adhesive is applied to both of the adherends to be joined, and these adhesive layers are dried and then bonded to each other, thereby expressing a high adhesive force immediately after the bonding. Because of these characteristics, it is expected to be used as water-based contact adhesiveness, but its adhesive performance such as initial adhesive strength and water resistance is inferior to that of solvent-based adhesives, and this improvement has been a problem.
[0005]
For example, Japanese Patent Application Laid-Open Nos. 50-22084 and 06-287360 disclose a method for producing a polychloroprene latex adhesive in which chloroprene is polymerized in the presence of an unsaturated carboxylic acid, polyvinyl alcohol and a chain transfer agent. However, such polychloroprene latex has insufficient storage stability and adhesion water resistance.
[0006]
[Problems to be solved by the invention]
The present invention solves such problems of the prior art, and provides a polychloroprene latex composition for aqueous adhesives excellent in initial adhesive strength, normal adhesive strength, water resistance, and storage stability, and a method for producing the same. And an adhesive composition using the same.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have made polyvinyl alcohol, polymerized chloroprene and a specific amount of ethylenically unsaturated carboxylic acid, and a PH adjuster and a radical scavenger. By adding an agent, it was found that a polychloroprene latex composition excellent in storage stability and adhesion water resistance was obtained, and the present invention was completed.
[0008]
That is, the present invention polymerizes 100 parts by mass of chloroprene and 0 parts by mass of ethylenically unsaturated carboxylic acid and less than 2 parts by mass in the presence of 0.5 to 10 parts by mass of polyvinyl alcohol, and then adjusts the pH regulator and radical. A polychloroprene latex composition obtained by adding a scavenger and having a gel content of the obtained chloroprene polymer of 10 to 70% by mass, a production method thereof, and an adhesive composition using the same It is a thing.
[0009]
The present invention will be described in detail below. The chloroprene polymer in the present invention is a copolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene) and an ethylenically unsaturated carboxylic acid homopolymer, or a monomer capable of copolymerization with chloroprene. It is a copolymer obtained by further copolymerizing at least one of the bodies.
[0010]
Examples of the monomer copolymerizable with chloroprene in the present invention include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, and esters of acrylic acid. And esters of methacrylic acid, and two or more kinds may be used as necessary.
[0011]
Specific examples of the ethylenically unsaturated carboxylic acid in the present invention include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, citraconic acid, glutaconic acid, etc., and these may be used alone or in combination of two or more. Can also be used. In the present invention, acrylic acid and methacrylic acid are preferably used, and methacrylic acid is particularly preferably used.
[0012]
Moreover, the addition amount of the ethylenically unsaturated carboxylic acid in this invention exceeds 0 mass part per 100 mass parts of chloroprenes, and is less than 2 mass parts. More preferably, it is 0.7-1.5 mass parts. When the addition amount of the ethylenically unsaturated carboxylic acid is 0 part by mass, the stability of the latex is inferior, so that the production is difficult, and the adhesive properties, particularly the heat resistance is inferior. When the addition amount of the ethylenically unsaturated carboxylic acid is 2 parts by mass or more, the decrease in water resistance is large.
[0013]
The polyvinyl alcohol in the present invention is not particularly limited, but those having a degree of saponification of 60 to 98 mol% are preferred. More preferably, the degree of saponification is 75 to 95 mol%, and still more preferably the degree of saponification is 75 to 85 mol%.
Moreover, the thing of the range whose polymerization degree of polyvinyl alcohol is 200-3000 is preferable. More preferably, the degree of polymerization is 200 to 700, and still more preferably the degree of polymerization is 200 to 700.
When the polyvinyl alcohol is within this range, the polymerization operation can be performed stably, and the latex obtained is excellent in stability and stable at a high concentration.
[0014]
As addition amount of polyvinyl alcohol in this invention, addition of 0.5-10 mass parts is preferable with respect to 100 mass parts of chloroprene. More preferably, it is 2-5 mass parts, More preferably, it is 2.5-4.5 mass parts. When the addition amount of polyvinyl alcohol is less than 0.5 parts by mass, the emulsifying power is not sufficient, and aggregates are likely to occur frequently during the polymerization reaction. On the other hand, when the amount exceeds 10 parts by mass, thickening may occur during the polymerization reaction, which may hinder stirring and cause abnormal heat generation, which may make production difficult.
[0015]
Further, the polychloroprene latex composition in the present invention needs to have a toluene-insoluble gel content in the range of 10 to 70% by mass, and preferably in the range of 15 to 60% by mass. When the gel content is less than 10% by mass, the adhesive strength, heat resistance and shear strength are lowered. On the other hand, when the gel content exceeds 70% by mass, the initial adhesiveness is lowered and the water resistance is remarkably lowered.
[0016]
The gel content of the polychloroprene latex composition can be controlled by (1) use of a chain transfer agent and its amount, (2) polymerization temperature, and (3) control of the polymerization rate.
[0017]
First, the chain transfer agent is not particularly limited as long as it is generally used in the production of chloroprene polymers. For example, long chain alkyl mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, diisopropylxanthogen disulfide and diethyl Known alkyl chain transfer agents such as dialkylxanthogen disulfides such as xanthogen disulfide and iodoform can be used.
[0018]
Next, the polymerization temperature is preferably in the range of 0 to 55 ° C in terms of polymerization control. In order to perform the polymerization reaction more smoothly and safely, the polymerization temperature is preferably 30 to 50 ° C.
[0019]
The final polymerization rate is preferably 80% by mass or more, more preferably 90% by mass or more.
[0020]
In this invention, it is preferable that the solid content concentration of a polychloroprene latex composition exists in the range of 40-65 mass%, More preferably, it is the range of 45-60 mass%. By setting a higher solid content concentration, the drying speed is fast and the latex has an excellent initial adhesiveness. The solid content concentration can be adjusted by the ratio of the monomer and water during polymerization, but can be adjusted by concentration after polymerization.
[0021]
Since the chloroprene polymer in the present invention is acidic immediately after polymerization and is in an unstable normal state, it is necessary to adjust the pH to 6 to 9. Preferably, PH is 6.5 to 8.5. If the pH is less than 6, it is likely to be altered such as coagulation and separation after long-term storage. Further, an alkaline solution having a pH exceeding 9 is not preferable for handling.
[0022]
As the PH adjuster in the present invention, sodium carbonate, potassium carbonate, trisodium phosphate, disodium hydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, tripotassium citrate, dipotassium hydrogen citrate, sodium acetate , Potassium acetate, sodium tetraborate and other weak acid salts are preferably contained in an amount of 0.1 parts by mass, more preferably 0.3 parts by mass or more, per 100 parts by mass of chloroprene. Weak acid salts are necessary to increase the buffer capacity of the polychloroprene latex composition, and if it is less than 0.1 parts by mass, it is not possible to suppress a decrease in PH during storage. When the pH of the polychloroprene latex is less than 6 with only the weak acid salts, basic substances such as sodium hydroxide, potassium hydroxide and diethanolamine can be optionally used in combination.
[0023]
The method for adding the PH adjuster in the present invention is not particularly limited, and the PH adjuster powder can be added directly or diluted to an arbitrary ratio with water.
[0024]
Examples of the radical scavenger of the present invention include polymerization inhibitors such as thiodiphenylamine, diethylhydroxylamine, hydroquinone, pt-butylcatechol, 1,3,5-trihydroxybenzene, hydroquinone methyl ether, 2,6-di- t-butyl-4-methylphenol, 2,2-methylenebis (6-t-4-methylphenol), 4,4-butylenebis (6-t-butyl-3-methylphenol), ethylenebis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like Mention may be made of a sealing agent.
[0025]
As the radical scavenger of the present invention, it is preferable to use 0 to 0.5 parts by mass of the polymerization inhibitor and 0.1 to 1.5 parts by mass of the antioxidant. When the antioxidant is less than 0.1 parts by mass, gelation during storage of the polychloroprene latex composition cannot be suppressed.
[0026]
The method for adding the radical scavenger of the present invention is not particularly limited, but a method in which a radical scavenger dissolved in a chloroprene monomer is added to a chloroprene polymer, and the monomer is degassed and removed. The method of adding the emulsion obtained by addition to the chloroprene polymer is preferable in consideration of the dispersion state of the radical scavenger in the polychloroprene latex composition.
Catalysts used for polymerization of the polychloroprene latex of the present invention include inorganic oxides such as potassium sulfate, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, etc. An organic peroxide etc. can be mentioned. As the catalyst, potassium sulfate is preferably used for performing stable polymerization. Moreover, it is preferable to use potassium sulfate in 0.1-5 mass% aqueous solution.
[0028]
In order to enhance the activity of the catalyst used for the polymerization of the polychloroprene latex of the present invention, sodium sulfite, iron (II) oxide, anthraquinone β sodium sulfonate, formamidine sulfonic acid, L-ascorbic acid, etc. may be added. it can.
[0029]
Examples of the tackifier resin of the present invention include rosin ester resin, terpene phenol resin, coumarone-indene resin, aliphatic hydrocarbon resin, aromatic resin and the like. As the tackifier resin, an emulsion of a terpene phenol resin or a rosin ester resin is preferable in terms of developing the initial adhesive force and water resistance of the adhesive composition.
[0030]
The addition amount (in terms of solid content) of the tackifying resin is preferably 10 to 100 parts by mass and particularly preferably 20 to 70 parts by mass with respect to 100 parts by mass of the polychloroprene latex. If it is less than 10 parts by mass, the initial adhesive force may be inferior, and if it exceeds 100 parts by mass, formation of the adhesive film is likely to be hindered.
[0031]
Examples of the metal oxide in the present invention include zinc oxide, titanium oxide and iron oxide. Zinc oxide and titanium oxide are preferable for improving the water resistance of the adhesive composition, and the use of zinc oxide is particularly preferable.
[0032]
The addition amount of the metal oxide is preferably 0.2 to 5.0 parts by mass, particularly preferably 0.5 to 3.0 parts by mass. If it is less than 0.2 parts by mass, the water resistance of the adhesive composition may be insufficient, and if it exceeds 5.0 parts by mass, the initial adhesive force tends to deteriorate.
[0033]
The adhesive composition of the present invention includes inorganic fillers such as calcium carbonate, silica, talc and clay, plasticizers / softeners such as dibutyl phthalate and process oil, thickeners such as sodium polyacrylate, water-soluble polyurethane and methylcellulose. Surfactants such as polyoxyalkylene alkyl ethers, 1: 2 mol type aliphatic alkanolamides, 1: 1 mol type diethanolamide, polyoxyethylene stearate, various anti-aging agents, UV absorbers and antioxidants It can mix | blend arbitrarily as needed.
[0034]
The adhesive composition of the present invention is made by mixing polychloroprene latex, tackifying resin, metal oxide, and the like, but the mixing apparatus is not particularly limited, such as three-one motor, homogenizer media mill, colloid mill, etc. Known devices can be used.
[0035]
The polychloroprene latex adhesive obtained by the present invention is suitable for bonding of the same kind or different kinds of paper, wood, cloth, leather, leather, rubber, plastic, foam, earthenware, glass, ceramic, metal, etc. . With regard to the construction method at the time of bonding, brush coating, trowel coating, spray coating, roll coater coating and the like are possible.
[0036]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention. In the following examples, “part” and “%” are based on mass unless otherwise specified.
[0037]
Example 1
Using a reactor with an internal volume of 3 liters, under nitrogen flow, 94 parts of water and 3.5 parts of polyvinyl alcohol (Unitika UMR-20H, degree of saponification 79 mol%, degree of polymerization 380) were added and heated (60 ° C.). Dissolved. After cooling this aqueous solution to near room temperature, 99 parts of chloroprene monomer, 0.5 part of methacrylic acid, and 0.3 part of octyl mercaptan were added thereto. While maintaining this at 45 ° C., polymerization was carried out using sodium sulfite and potassium persulfate as initiators. The final polymerization rate was 98%.
[0038]
Next, 10% trisodium phosphate aqueous solution (0.5 parts in terms of solid content was added to adjust the pH to this polychloroprene latex, and then a 1: 2 molar fatty acid alkanolamide (manufactured by Diamond Simoyalok Chemical Co., Ltd.). 3 parts of a 20% aqueous solution and 0.5 part of an emulsion of 2,6 di-t-butyl-4-methylphenol (Cerosol H633, manufactured by Chukyo Yushi Co., Ltd.) in terms of solid content is added to form a polychloroprene latex composition. I got a thing.
[0039]
Next, the following measurements were performed on this polychloroprene latex composition.
[Gel content measurement]
The latex sample was freeze-dried to make a precision balance A. After dissolving in toluene (prepared to 0.6%), the gel was separated using a centrifuge and further using a 200-mesh wire mesh. The gel was air-dried and then dried in an atmosphere at 110 ° C. for 1 hour, and weighed precisely to obtain B.
The gel content was calculated according to the following formula.
Gel content = B / A × 100 (%)
The results are shown in Table 1.
[PH measurement]
The latex sample was adjusted to 20 ° C. in a constant temperature water bath, and then PH was measured with a PH meter.
[Storage stability test]
The latex sample was allowed to stand at 40 ° C. for 2 months in an environmental test machine set to 40 ° C., and then PH and gel content were measured to check for changes.
[0040]
[Initial peel strength]
The adhesive composition was prepared according to the formulation shown in Table 1.
Next, an adhesive composition of 300 g (solid content) / m ² was applied to each of two canvases (25 × 150 mm) with a brush, dried for 9 minutes at 80 ° C., and allowed to stand for 1 minute at room temperature. It was pressed with a laminated hand roller.
After 10 minutes, the 180 ° peel strength was measured using a tensile tester at a pulling rate of 200 mm / min.
[Normal peel strength]
The adhesive composition was prepared according to the formulation shown in Table 1.
Next, an adhesive composition of 300 g (solid content) / m ² was applied to each of two canvases (25 × 150 mm) with a brush, dried for 9 minutes at 80 ° C., and allowed to stand for 1 minute at room temperature. It was pressed with a laminated hand roller.
Seven days after pressing, 180 ° peel strength was measured using a tensile tester at a pulling rate of 200 mm / min.
[0041]
[Water resistance]
The adhesive composition was prepared according to the formulation shown in Table 1.
Next, an adhesive composition of 300 g (solid content) / m ² was applied to each of two canvases (25 × 150 mm) with a brush, dried for 9 minutes at 80 ° C., and allowed to stand for 1 minute at room temperature. It was pressed with a laminated hand roller.
Seven days after pressing, it was immersed in water for 2 days, and a 180 ° peel strength was measured at a pulling rate of 200 mm / min using a tensile tester.
[0042]
[Example 2]
In Example 1, polychloroprene latex was prepared in the same manner as in Example 1, except that 1.0 part of methacrylic acid and 0.6 part of 10% sodium carbonate aqueous solution in terms of solid content were used. The gel content, PH, and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.
[0043]
Example 3
In Example 1, polychloroprene latex was prepared in the same manner as in Example 1 except that 1.5 parts of methacrylic acid and 0.8 parts of 10% aqueous sodium carbonate solution were converted into solids. The gel content, PH, and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.
[0044]
Example 4
In Example 2, a polychloroprene latex was prepared in the same manner as in Example 2 except that 0.38 part of octyl mercaptan was used. The gel content, PH, and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.
[0045]
Example 5
In Example 2, a polychloroprene latex was prepared in the same manner as in Example 2 with 3.0 parts of polyvinyl alcohol. The gel content, PH, and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.
[0046]
Example 6
In Example 4, 3.5 parts of Denkapoval B-05 as polyvinyl alcohol, 0.3 parts of 10% trisodium citrate aqueous solution in terms of solid content, 0.3 parts of 20% diethanolamine, diethylhydroxylamine A polychloroprene latex was prepared in the same manner as in Example 4 except that 0.02 part of an emulsion of 2,6-t-butyl-4-methylphenol was 0.3 part in terms of solid content. Further, the water was evaporated under reduced pressure and concentration was performed, and the solid content concentration was adjusted to 55%. The gel content, PH, and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 1.
[0047]
[Comparative Example 1]
In Example 1, polychloroprene latex was prepared in the same manner as in Example 1, except that 3.0 parts of methacrylic acid and 0.6 parts of 10% aqueous sodium carbonate solution in terms of solid content and 0.6 parts of 20% diethanolamine were used. The gel content, PH and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 2.
[0048]
[Comparative Example 2]
In Example 2, 0.05 part of octyl mercaptan was used to prepare a polychloroprene latex as in Example 2. The gel content, PH and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 2.
[0049]
[Comparative Example 3]
In Example 2, polychloroprene latex was prepared in the same manner as in Example 2 with diethanolamine at 0.6 parts in terms of solid content, and then stored under the conditions of the above storage stability test. As a result, PH decreased to 5.4. The gel content, pH and adhesive properties of the latex before storage were measured in the same manner as in Example 1 and the results are shown in Table 2. However, the latex after storage is unstable because the pH is lower than the range of the present invention. It is obvious that it is easy to solidify.
[0050]
[Comparative Example 4]
In Example 2, a polychloroprene latex was prepared in the same manner as in Experimental Example 2 without adding an emulsion of 2,6-t-butyl-4-methylphenol. The gel content, PH and adhesive properties were measured in the same manner as in Example 1, and the results are shown in Table 2.
[0051]
[Table 1]

[0052]
Note 1) PVA; UMR-20H, saponification degree 79 mol%, polymerization degree 380 (manufactured by Unitika)
Note 2) PVA; B-05, saponification degree 88 mol%, polymerization degree 550 (manufactured by Denki Kagaku Kogyo Co., Ltd.)
Note 3) Cellosol H633: 2,6-di-t-butyl-4-methylphenol emulsion (manufactured by Chukyo Yushi Co., Ltd.), the amount added is converted to solid content Note 4) Terpene-modified phenol resin emulsion; Tamanol E-100 (Arakawa Chemical) (Manufactured by Kogyo)
Note 5) Zinc oxide emulsion (manufactured by Osaki Kogyo Co., Ltd.).
[Table 2]

[0054]
【The invention's effect】
From the comparison of the above examples and comparative examples, it is clear that the polychloroprene latex of the present invention is excellent in storage stability, initial adhesive strength and water resistance, such as wood bonding such as plywood, paper material, synthetic resin, steel plate It is possible to provide a polychloroprene latex composition particularly suitable for bonding such as the above and a method for producing the same.

Claims (4)

After polymerizing 100 parts by mass of chloroprene and 0 parts by mass of ethylenically unsaturated carboxylic acid in the presence of 0.5 to 10 parts by mass of polyvinyl alcohol , a weak acid salt and a radical scavenger as a PH regulator are added. A polychloroprene latex composition obtained by adding and having a gel content of 10 to 70% by mass and a pH of 6 to 9 in the obtained chloroprene polymer. The polychloroprene latex composition according to claim 1, wherein the saponification degree of polyvinyl alcohol is 75 to 85 mol%. An adhesive composition obtained by adding a tackifying resin and a metal oxide to the polychloroprene latex composition according to claim 1 or 2 . The adhesive composition according to claim 3 , wherein the metal oxide is zinc oxide.