JP2007291188A - High solid content solvent-based rubber adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with the problem that although a polychloroprene rubber adhesive has heretofore been used extensively in various fields in virtue of its excellent adhesion to various adherends and its highly reliable adhesive performance, it causes a sick building syndrome because it contains an organic solvent such as toluene, xylene, or acetone belonging to the 13 indoor chemicals which are specified in 2002 by the Ministry of Health, Labour and Welfare in Japan and are required to meet indoor emissions in concentrations not higher than the guideline values for their indoor concentrations. <P>SOLUTION: The problem is solved by providing a high solids content solvent-based rubber adhesive comprising an acid-modified styrene elastomer or both an acid-modified styrene elastomer and an elastomer, a ketimine-type silane coupling agent or an amino-type silane coupling agent, a tackifying resin, etc., and an organic solvent which is not a chemical belonging to the 13 indoor chemicals specified by the Ministry of Health, Labour and Welfare in Japan. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high solid content rubber-based solvent-type adhesive, and in particular, has a high solid content, is excellent in storage stability, coating property and adhesion performance, and has a VOC emission amount of 70 of the current chloroprene rubber-based solvent-type adhesive. % High solid content rubber-based solvent-type adhesive that can be suppressed to less than 1%.

  Polychloroprene rubber-based solvent-based adhesives are widely used in woodworking, construction, and vehicle applications due to their excellent characteristics such as wide adhesion to adherends, rapid initial adhesion, and heat resistance. . In particular, it is useful in the field of construction work because of the above features.

The polychloroprene rubber-based solvent-type adhesive is capable of dissolving a chloroprene polymer (hereinafter abbreviated as CR), a tackifier resin, and magnesium oxide as a vulcanizing agent alone. Mixing solvents such as toluene, xylene, and ethylbenzene with poor solvents such as n-hexane, cyclohexane, acetone, methyl ethyl ketone, and ethyl acetate that cannot dissolve chloroprene rubber alone to provide drying properties. Prepared. The composition of the chloroprene rubber-based solvent-type adhesive has a solid content of about 20% and the remaining 80% is occupied by the organic solvent. In addition, since it is a double-sided coating and an application amount of about 150 g per m ² of the coating material on one side of the adherend is adopted, the VOC emission amount into the atmosphere is 200 g or more per m ² of the coating area of the adherend. ing.

  Dissipation of organic solvent into the atmosphere can be suppressed by lowering the composition ratio of organic solvent in the adhesive and increasing the solid content, but there is a problem that the applicability of the adhesive, particularly the low application amount suitability, is deteriorated. . Furthermore, in recent years, in addition to toluene and xylene, which are good solvents for CR, ethylbenzene, styrene, formaldehyde, paradichlorobenzene, chloropyripos, di-n-butyl phthalate, di-2-ethylhexyl phthalate, tetradecane, diazinon, acetaldehyde, fenocarb Was designated in 2002 as 13 substances designated by the Ministry of Health, Labor and Welfare as a causative substance of sick house syndrome, and a guideline value for indoor concentration is shown. At the same time, the revision of “School Environmental Sanitation Standards” requires the indoor concentration of the above substances to be below the guideline value. In addition, chlorinated solvents are subject to restrictions on the use of chlorofluorocarbon solvents in the same way as chlorofluorocarbons due to ozone depletion problems.

On the other hand, VOCs such as n-hexane, acetone, and ethyl acetate are air pollutants and have a problem of impact on human health, but the achievement rate of environmental standards remains low. For this reason, the Environmental Agency is obliged to measure the emission concentration of VOCs at factories and business establishments and to notify the prefectural governor in 2006 and to enforce the management requirement below the specified emission concentration. In addition, self-regulation of emission reduction efforts of each industry group is also planned, and the target is to reduce the VOC emission value to 70% or less by 2010 compared to 2000.
JP-A-8-302316 JP 2000-96014 A

In view of the above situation, the present invention does not contain 13 substances designated by the Ministry of Health, Labor and Welfare such as toluene, xylene, and ethylbenzene, which are the causative substances of sick house syndrome. Adhesive performance can be obtained even with a coating amount of about 100 g per m ^2, and a high solid content rubber solvent type adhesive that can reduce the amount of VOC emission to the atmosphere to 70% or less of conventional chloroprene rubber solvent type adhesives. It is intended to provide an agent.

  The present invention provides a rubber-based solvent-based adhesive that has good coatability even at a high solid content, improves low coating amount suitability, and suppresses the VOC emission amount to 70% or less by securing adhesive performance. An acid-modified styrenic elastomer (hereinafter abbreviated as ASE) or ASE and elastomer (hereinafter abbreviated as E, ASE when ASE alone is blended, or both ASE and E are blended. The aforesaid problems have been solved by means such as blending adjustment of ketimine-based silane coupling agent or amino-based silane coupling agent, tackifying resin, and non-use of causative substances of sick house syndrome. Is.

  The high solid content rubber-based solvent adhesive according to the present invention has good coating properties, low coating amount suitability and excellent adhesive performance, and includes 13 substances designated by the Ministry of Health, Labor and Welfare such as toluene, xylene and ethylbenzene which are the causative substances of sick house syndrome. In addition, since the VOC emission amount can be suppressed to 70% or less of the current chloroprene rubber adhesive, there is little environmental pollution, and it can be used for various applications with confidence. In addition, it has storage stability, applicability, low coating amount suitability, and adhesion performance, so it has remarkable effects such as easy storage and use, easy application and non-uniform coating, and good adhesion performance. Is obtained.

  E used in the present invention includes styrene-based elastomers such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, styrene- Examples include ethylene / propylene-styrene copolymer, SBR, acrylonitrile-butadiene. Among these, a 25 wt% toluene solution having a viscosity of 400 to 20000 mPa · s at 20 ° C. is preferable from the standpoints of solution viscosity and coating properties.

  ASE can be obtained, for example, by adding a modifier to a styrene elastomer. As the styrene-based elastomer, a styrene-butadiene block copolymer comprising a polymer block mainly composed of styrene and a polymer block mainly comprising butadiene or isoprene, or a block copolymer of styrene-isoprene, or these Mention may be made of elastomers obtained by hydrogenation of block copolymers. Specific examples include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene / butylene-styrene block copolymer, and a styrene-ethylene / propylene-styrene copolymer. It is done.

  Examples of the modifier include maleic acid and its anhydride, maleic acid ester, fumaric acid and its anhydride, fumaric acid ester, itaconic acid and its anhydride, itaconic acid ester, crotonic acid and its anhydride, acrylic acid, crotonic acid And anhydrides thereof, methacrylic acid, methacrylic acid esters, methacrylic acid amides, and the like. Of these, acid anhydrides are suitable for use because of their high reactivity with amino silane coupling agents produced by the reaction of ketimine silane coupling agents with moisture or with compounded amino silane coupling agents. .

  These modifiers can be used alone or in combination of two or more. The modification method is a known method, for example, a method of reacting while melting and kneading in a range of 150 to 350 ° C. using a roll mill, a Banbury mixer, an extruder, or the like, or a heat reaction in a solvent such as benzene, toluene, xylene. Methods can be adopted. In order to accelerate the reaction, it is effective that a radical generator such as benzoyl peroxide or azobisisobutylnitrile is present in the reaction system.

  The high solid content rubber-based solvent-type adhesive according to the present invention is blended so that the ASE weight ratio (hereinafter referred to as the rubber ratio) with respect to the total elastomer weight is 30% by weight or more in order to ensure adhesion performance. . If the blending ratio is less than 30% by weight, sufficient adhesion performance cannot be obtained. Further, the blending ratio of the total elastomer in the high solid content rubber solvent adhesive is preferably 10 to 30% by weight. If it is less than 10% by weight, it is difficult to increase the solid content and the adhesiveness is also lowered, which is not preferable. On the other hand, if it exceeds 30% by weight, the viscosity becomes high and the applicability is lowered, so it is not suitable.

  As tackifying resin, alkylphenol resin such as t-butylphenol resin, terpene modified phenol resin, terpene resin, rosin modified phenol resin, rosin resin, hydrogenated rosin ester resin, petroleum resin, coumarone-indene resin, α-pinene resin, etc. The tackifying resin is preferably blended in an amount of 70 parts by weight or more based on 100 parts by weight of the total elastomer. If it is less than 70 parts by weight, the tackiness will be difficult, which is not suitable.

  Further, a ketimine silane coupling agent or an amino silane coupling agent is blended in order to perform moisture curing. By adding a ketimine silane coupling agent, it reacts with moisture in the air to decompose (hydrolyze) to produce an amine compound with active hydrogen, and this amine compound reacts with an acid anhydride group or carboxyl group. At the same time, moisture curing proceeds by a dehydration bonding reaction between hydroxyl groups generated by reaction of an alkoxyl group such as a methoxy group bonded to a silicon atom with water. Moisture curing proceeds in the same manner by blending an amino silane coupling agent.

  Examples of ketimine silane coupling agents include N- (1,3 dimethylbutylidene) -3- (trimethoxysilyl) -1-propanamine, N- (1,3-dimethylbutylidene) -3- (triethoxy And silyl) -1-propanamine and N- (1,3-dimethylbutylidene) -3- (methyldiethoxysilyl) -1-propanamine.

  Examples of amino silane coupling agents include bis (trimethoxysilylpropyl) silane, γ-N-phenylaminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropyltrimethoxysilane, and γ-amino. Examples include propyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyl-methyldiethoxysilane.

  In the high solid content rubber-based solvent-type adhesive according to the present invention, in order to further enhance the effect of moisture curing, the blending ratio of ASE with respect to the total elastomer (hereinafter referred to as rubber ratio) is 30% by weight or more with respect to the total elastomer weight. The blending ratio of the ketimine silane coupling agent or amino silane coupling agent is preferably 1% by weight or more. When these are not satisfied, there is little cross-linking due to moisture curing, and sufficient adhesive strength cannot be obtained.

  The organic solvent used in the high solid content rubber solvent type adhesive according to the present invention is not toluene, xylene, ethylbenzene, methylene chloride or the like which causes sick house syndrome, but n-hexane, cyclohexane, methylcyclohexane, acetone. These are methyl ethyl ketone, ethyl acetate, butyl acetate, etc., and the elastomer is dissolved only by a mixture of poor solvents having poor solubility of the elastomer alone.

  The high solid rubber solvent type adhesive according to the present invention can be appropriately blended with a dehydrating agent in an amount of 0.5% by weight or more in order to eliminate the concern that the reaction proceeds due to moisture during the storage and thickens. Examples of the dehydrating agent include monofunctional isocyanate compounds, silane coupling agents, silica gel, zeolite, calcium chloride, and anhydrous calcium sulfate.

  In addition, in the high solid content rubber solvent-type adhesive according to the present invention, the organic solvent compounding ratio is set in consideration of the total elastomer compounding ratio, the tackifying resin compounding ratio, etc. in order to suppress the use ratio of the organic solvent. The solid content is 30% by weight or more.

  The high solid content rubber-based solvent adhesive according to the present invention is applied as an air spray application, airless spray application, brush application, roll application, brush application, roll coater application, flow coater application, bar coater application, iron application. A coating method such as can be employed. In order to improve the coatability, the viscosity is preferably 1 Pa · s / 20 ° C. or less in air spray coating, airless spray coating, and flow coater coating. In brush coating, roll coating, brush coating, roll coater coating, bar coater coating, iron coating, etc., the viscosity is preferably 20 Pa · s / 20 ° C. or less. If it exceeds this, the applicability is poor, and the low applicability at the time of application cannot be obtained.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Note that parts by weight are simply expressed as parts.

Example: Tuftec M1913 (made by Asahi Kasei Corporation, St / EB {St: styrene, EB: ethylenebutylene} ratio: 30/70, acid value = 10 mg CH ₃ ONa / g, trade name) as ASE, styrene elastomer as E Tuffprene A (Asahi Kasei Co., Ltd., St / Bd {St: styrene, Bd: butadiene} ratio: 40/60, 25% toluene solution viscosity: 650 cp, trade name), ester which is a rosin ester resin as a tackifying resin Gum 105 (made by Arakawa Chemical Industry Co., Ltd., trade name), KBE9103 (made by Shin-Etsu Chemical Co., Ltd., specific gravity 0.924 / 25 ° C., refractive index 1.437 / 25 ° C., trade name) as a ketimine silane coupling agent KBE602 as an amino-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., specific gravity 0.97 / 25 ° C., refractive index 1) 445/25 ° C., trade name), Zeorum A-4 (zeolite, trade name, manufactured by Tosoh Corporation) as a zeolite-based dehydrating agent, and acetone, cyclohexane, etc. as a solvent are blended as shown in Tables 1 and 2 and dissolved. High solid content rubber solvent type adhesives of Examples and Comparative Examples were prepared.
Comparative Example M-100 as chloroprene rubber (manufactured by Denki Kagaku Kogyo Co., Ltd., Mooney viscosity: 100 ML _{1 + 4} , 100 ° C., crystallinity: medium, trade name), magnesium oxide (MgO) as vulcanizing agent, and tackifying resin A chloroprene rubber solvent-based adhesive of Comparative Example 5 was prepared by a known production method using phenol resin CKM-1634 (manufactured by Showa Polymer Co., Ltd., trade name) and toluene, n-hexane, and acetone as solvents. Tables 1 and 2 below show the results of a comparative test of the properties and performances of the high solid content rubber solvent adhesives and the chloroprene rubber solvent adhesives prepared in Examples and Comparative Examples.

粘度：回転型粘度計(BM型、 ロータ NO2 、30rpm)で測定
低温安定性：−５℃中に１ヶ月保存し、ゲル化もしくは著しい増粘をしていないかどうかを確認する。○：安定、×：ゲル化もしくは著しい増粘
長期保存性：４０℃×１ヶ月後の増粘度合い。◎：増粘１０％以内、○：増粘１０〜１５％、△：増粘１５〜２０％
塗布性： ３０センチ角、厚み５．５ｍｍのＪＩＳA５９０５（２００３年制定）規格 ＭＤＦ板（アルパインＭＤＦインダストリー株式会社製、比重０．７６）上にエアースプレー塗布した際の塗りやすさを評価する。○：塗布性が良好で塗布ムラが無い。×：塗布性が悪く塗布ムラが出る。
環境性 ： シックハウス症候群の原因物質である厚生労働省指定１３物質が配合されているか、ＶＯＣ放散量が多いかどうかで評価する。○：配合なし及びＶＯＣ放散量が少ない、×：配合あり及び／又はＶＯＣ放散量が多い
常態強度（Ｎ／ｍｍ^２）：被着体として両面とも厚み５．５ｍｍのＪＩＳＡ５９０５（２００３年制定）規格 ＭＤＦ板（アルパインＭＤＦインダストリー株式会社製、比重０．７６）を使用し、エアースプレーにより両面に塗布する。実施例ならびに比較例１〜４、６については塗布量として片面につき１００ｇ／ｍ^２塗布、比較例５については塗布量として片面につき１５０ｇ／ｍ^２塗布し、オープンタイムとして２０℃に１０分間放置し、塗布面を重ね合わせローラー圧締して試験片を作成したのち、２３℃で７日間養生した。養生後、２３℃の雰囲気下で引張りせん断接着強さ（Ｎ／ｍｍ^２ 引張り速度 ５ｍｍ／分、接着面積２５×２５ｍｍ^２、試験数５個）を測定して平均値を算出した。
耐熱強度（Ｎ／ｍｍ^２）：常態強度と同一条件で試験片の作成と養生した試験片について、８０℃中で３０分間放置後、そのままの雰囲気下で引張りせん断接着強さ（Ｎ／ｍｍ^２ 引っ張り速度５ｍｍ／分、接着面積２５×２５ｍｍ^２、試験数５個）を測定して平均値を算出した。
ＶＯＣ放散量（ｇ／ｍ^２）：１ｍ^２を接着する際に大気中に放散されるＶＯＣ量。塗布量×接着剤中の溶剤比率より算出。
ＶＯＣ放散比率（％）：クロロプレンゴム系接着剤(比較例５)のＶＯＣ放散量を１００％とした場合の比率。

Viscosity: Measured with a rotational viscometer (BM type, rotor NO2, 30 rpm) Low temperature stability: Store at -5 ° C for 1 month to check for gelation or significant thickening. ○: Stable, ×: Gelation or significant thickening long-term storage stability: 40 ° C x viscosity increase after 1 month. ◎: Within 10% thickening, ○: 10-15% thickening, Δ: 15-20% thickening
Applicability: JIS A 5905 (established in 2003) standard 30 cm square and thickness 5.5 mm Standard MDF board (manufactured by Alpine MDF Industry Co., Ltd., specific gravity 0.76) is evaluated for ease of application. ○: Coating property is good and there is no coating unevenness. X: Coating property is poor and coating unevenness appears.
Environmental characteristics: Evaluated based on whether 13 substances specified by the Ministry of Health, Labor and Welfare, which is the causative substance of sick house syndrome, are blended or the amount of VOC emission is large. ○: No blending and low VOC emission amount ×: Normal strength (N / mm ² ) with blending and / or large VOC emission amount: JISA 5905 (established in 2003) standard with a thickness of 5.5 mm on both sides as an adherend An MDF plate (manufactured by Alpine MDF Industry Co., Ltd., specific gravity 0.76) is used, and is applied to both sides by air spray. For Examples and Comparative Examples 1 to 4 and 6, the application amount was 100 g / m ² per side, and for Comparative Example 5, the application amount was 150 g / m ² per side, and the open time was left at 20 ° C. for 10 minutes. The coated surfaces were overlapped and pressed with a roller to prepare a test piece, which was then cured at 23 ° C. for 7 days. After curing, the tensile shear bond strength (N / mm ² pulling speed 5 mm / min, bonding area 25 × 25 mm ² , number of tests 5) was measured under an atmosphere of 23 ° C., and the average value was calculated.
Heat resistance (N / mm ^2): For normal strength and specimen was cured and creation of the specimen under the same conditions, allowed to stand in a 80 ° C. 30 minutes, strong tensile shear bond under neat atmosphere of (N / mm ² The average value was calculated by measuring a pulling speed of 5 mm / min, an adhesion area of 25 × 25 mm ^{2 and a} test number of 5).
VOC emission amount (g / m ² ): VOC amount released into the atmosphere when 1 m ² is bonded. Calculated from coating amount x solvent ratio in adhesive.
VOC emission ratio (%): Ratio when the VOC emission amount of the chloroprene rubber adhesive (Comparative Example 5) is 100%.

  The high solid content rubber-based solvent adhesive according to the present invention does not contain 13 substances designated by the Ministry of Health, Labor and Welfare that cause sick house syndrome such as toluene, xylene, and ethylbenzene as compared with conventional products. Since it has good heat-resistant adhesive strength, it can be used safely in a wide range of applications. In particular, since it is excellent in suitability for low coating amount, stable coating property can be secured even with a small amount of coating, which can greatly contribute to improvement of workability in application fields such as for woodworking, for vehicles, and for shoemaking.

Claims (4)

  An acid-modified styrene-based elastomer or an acid-modified styrene-based elastomer and an elastomer, a ketimine-based silane coupling agent or an amino-based silane coupling agent, a tackifying resin, and an organic solvent, the organic solvent containing the Ministry of Health, Labor and Welfare A high solid content rubber-based solvent-type adhesive characterized by containing no designated 13 substances.   2. The high solid content rubber solvent type adhesive according to claim 1, wherein the solid content is 30% by weight or more. 3. The high solid content rubber solvent-based adhesive according to claim 1, wherein the ratio of the acid-modified styrene elastomer to the total weight of the acid-modified styrene elastomer and the elastomer is 30% by weight or more.   The ketimine-based silane coupling agent or the amino-based silane coupling agent is blended in an amount of 1% by weight or more based on the total weight of the acid-modified styrenic elastomer and the elastomer. Or a high solid content rubber-based solvent-type adhesive.