JP2007262141A - Ethylene-vinyl acetate copolymer resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EVA emulsion composition which has high viscosity and high pseudoplasticity, is excellent in viscosity stability over time, contains no aggregate and has a wide application, with the aim of using a high-viscosity high-pseudoplasticity EVA emulsion in an adhesive for walls or ceiling boards, an adhesive for woodworking that is largely soaked up by a substrate, etc., since it hardly drips down when applied to a vertical surface or a ceiling and is hardly soaked up by a substrate. <P>SOLUTION: The resin composition contains the ethylene-vinyl acetate copolymer resin emulsion and a xanthan gum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ethylene vinyl acetate copolymer resin composition having high viscosity and high pseudoplasticity.

  An ethylene vinyl acetate copolymer resin (hereinafter abbreviated as EVA) emulsion is a resin emulsion obtained by emulsion copolymerization of vinyl acetate and ethylene. Since ethylene has a low glass transition temperature (Tg) and is nonpolar, its dry film is flexible and has excellent adhesion to a plastic substrate. Therefore, in addition to being used for adhesives such as plastic substrates, resin-impregnated paper, and water-repellent paper, which are difficult to bond with vinyl acetate resin emulsions, they are used for civil engineering. In addition, many of the commercially available EVA emulsions have a viscosity as low as several Pa · s or less, and the pseudoplasticity is also small. Therefore, conventionally, organic solvents such as toluene and xylene have been used as thickeners for EVA emulsions. Although the organic solvent has an effect of improving the adhesion to a plastic substrate or the like, the use of the organic solvent is avoided due to environmental problems.

However, it cannot be said that an effective method for thickening the EVA emulsion other than the addition of an organic solvent has been sufficiently studied so far. For example, a method of increasing the viscosity of an EVA emulsion by adding a large amount of a plasticizer is known, but a resin film formed from the emulsion has a low heat resistance and a low cohesive force, so that its use is extremely limited. It is a method. Patent Documents 1 and 2 relate to the manufacture of a honeycomb core and label adhesion, respectively, and mention are also made of a method for thickening an EVA emulsion. Although these give a viscosity and viscosity that can be applied to the application, a high viscosity increase that can be used for application to a vertical surface or a ceiling surface, application to a substrate with a large suction, etc. was not obtained. . Patent Document 3 examines the alkali thickening of the EVA emulsion itself. In this method, it is essential to adjust the pH to the alkali side, so that an unstable compound is added in the alkaline region. However, it was not a widely applicable technique.
JP-A-6-228518 JP 2003-41124 A JP 2002-121206 A

  The present invention relates to a resin composition containing an EVA emulsion that can be used in a wide range because it does not sag even when applied to a vertical surface or a ceiling surface, and is less sucked into a base material.

  A resin composition comprising an ethylene vinyl acetate copolymer resin emulsion and xanthan gum.

  Since the resin composition according to the present invention has high viscosity and high pseudoplasticity, it does not easily sag even when applied to a vertical surface or a ceiling surface, and suction into the substrate is small. Therefore, it can be used as an adhesive for walls / ceiling boards, an adhesive for woodworking with a large suction of the base material, and the like.

Hereinafter, the present invention will be described in detail.
The EVA emulsion is obtained by copolymerizing at least vinyl acetate and ethylene in the presence of an emulsifier such as polyvinyl alcohol (PVA) or a surfactant. There are no particular restrictions on the type and amount of emulsifier, the copolymerization monomer, the polymerization method, etc., and any of them can be used.

  Xanthan gum used in the present invention is a polysaccharide produced from a microorganism, Xanthomonas campestris, and is composed of mannose, glucose, and glucuronic acid. By adding to the EVA emulsion, the EVA emulsion can be thickened and pseudoplasticity can be imparted. Moreover, the thickening effect is stable over time. When xanthan gum is added, it is easy to form a lump of undissolved material when added directly to the EVA emulsion. Therefore, a method of adding a solution previously dissolved in water is preferable. The amount of xanthan gum added to the EVA emulsion varies depending on the viscosity of the base EVA emulsion and the required viscosity, but it is necessary to add 0.1 parts by weight or more with respect to 100 parts by weight of the EVA emulsion. Although there is no particular upper limit, it can be added within a range that satisfies the required performance in each application. In addition, although the present inventors also examined other natural polymer polysaccharides, none of them was inferior in viscosity increase or viscosity stability over time, and none was usable.

  Moreover, various compounding materials can be added according to each use aspect. Such compounding materials include plasticizers, solvents, high boiling point solvents, tackifiers, fillers, dispersants, leveling agents, water resistance agents, preservatives, antifoaming agents, surfactants, isocyanate compounds as crosslinking agents, An epoxy resin, a carbodiimide, an oxazoline-based resin, a rust inhibitor, and the like can be given.

  The present invention will be further described below with reference to examples and comparative examples. In addition, the compounding quantity displayed on Table 1 is a weight part. Needless to say, the present invention is not limited to the examples and comparative examples.

  EVA emulsion S-460HQ (manufactured by Sumitomo Chemtex Co., Ltd., solid content 60%, viscosity 13 Pa · s (however, according to the measurement method described later)), xanthan gum Roadpole 23 (manufactured by Rhodia Nikka Co., Ltd., trade name) ), A-7185 (manufactured by Toa Gosei Co., Ltd., polyacrylic acid, trade name), Accusol 880 (made by Rohm and Haas, urethane, trade name), RM2020NPR (Daiichi Kogyo Seiyaku Co., Ltd.) RM6000 (Daiichi Kogyo Seiyaku Co., Ltd., urethane, trade name), RM5000 (Daiichi Kogyo Seiyaku Co., Ltd., urethane, trade name), RM8W (Daiichi Kogyo Seiyaku) RM12W (Daiichi Kogyo Seiyaku Co., Ltd., urethane, product name), Latiko D (BASF, acrylic, trade name), UH-420 (Asahi Denka Kogyo, polyacrylic acid, trade name), V-280 (Gantz Kasei, acrylic, trade name) The resin composition of the Example of Table 1 and the comparative example of Table 2 was obtained by mix | blending by stirring with a propeller feather for 5 minutes. (In the case where there is dilution water during compounding, the thickener was added after being dispersed in dilution water in advance. The water in Examples 3 and 5 was added for viscosity adjustment. ) The properties and performance of each adhesive composition were evaluated. Since the viscosity was less than 15 Pa · s, the effect of thickening was small, so other evaluations were not performed.

評価方法
粘度
ＢＨ型回転粘度計を用い、２３℃雰囲気下においてローターＮｏ６、２回転／分で測定した値
ＴＩ値
ＢＨ型回転粘度計を用い、２３℃雰囲気下においてローターＮｏ６、２回転／分と２０回転／分で粘度を測定し、以下の式により計算した。

Evaluation method Viscosity TI value measured with a BH type rotational viscometer at rotor No. 6 at 2 revolutions / minute in a 23 ° C. atmosphere. The viscosity was measured at 20 revolutions / minute and calculated according to the following formula.

経時粘度安定性
４０℃雰囲気下にて１ヶ月間静置後、前記条件にて再度粘度を測定し、配合直後の粘度に対する１ヶ月後の粘度の変化率を確認した。
○：粘度変化率 ２０％以内
×：粘度変化率 ２０％超
混和性：配合後の凝集物の有無を目視で観察した。
○：凝集物の発生なし
×：凝集物が発生する
実施例１〜５ではＥＶＡエマルジョンを増粘するとともに擬塑性を付与することができた。また、実施例３、５はそれぞれ実施例２、４を水希釈したものに相当するが、擬塑性を維持したまま粘度を下げることができた。一方、比較例１は増粘したものの経時粘度安定性が不十分であり、比較例２は混和時に凝集物が発生し、比較例は３〜９においては十分な増粘効果が得られなかった。

Viscosity stability over time After standing for 1 month in an atmosphere at 40 ° C., the viscosity was measured again under the above conditions, and the rate of change in viscosity after 1 month relative to the viscosity immediately after compounding was confirmed.
○: Viscosity change rate within 20% ×: Viscosity change rate over 20% Miscibility: The presence or absence of aggregates after blending was visually observed.
○: No occurrence of aggregates ×: Generation of aggregates In Examples 1 to 5, the EVA emulsion was thickened and pseudoplasticity could be imparted. Examples 3 and 5 correspond to those obtained by diluting Examples 2 and 4 with water, respectively, but the viscosity could be reduced while maintaining pseudoplasticity. On the other hand, although Comparative Example 1 was thickened, the viscosity stability over time was insufficient, and Comparative Example 2 produced aggregates during mixing, and Comparative Examples 3 to 9 did not have a sufficient thickening effect. .

  Since the resin composition according to the present invention has high viscosity and high pseudoplasticity, it does not easily sag even when applied to a vertical surface or a ceiling surface, and suction into the substrate is small. Therefore, it can be used as an adhesive for walls / ceiling boards, an adhesive for woodworking with a large suction of the base material, and the like.

Claims (1)

  A resin composition comprising an ethylene vinyl acetate copolymer resin emulsion and xanthan gum.