JPS6052188B2 - antistatic agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-coating type antistatic agent that is applied to the surface of plastic to prevent charging.

Plastic sheets, films, etc. are often used in the field of packaging containers, etc., and it is generally desired that they have antistatic ability and transparency. In particular, plastics used for packaging items containing moisture are desired to have transparency and the ability to prevent fogging. In order to prevent static electricity or fogging of such plastics, antistatic agents and antifogging agents are applied. However, water-soluble acrylic resin, which is known as a surface-applied antistatic agent, has a slow dissolution rate in water and requires a long time to prepare an aqueous solution. It is difficult to apply with a printing machine, etc. because it is poorly soluble in water and requires a short drying time, and furthermore, if the sheet is matured by means such as vacuum forming after being applied to a sheet, the antistatic ability will be reduced. There are drawbacks.

In addition, when polyoxyethylene sorbitan fatty acid ester and N-hydroxyethyl-N-hydroxyalkylamine, which are also known as antistatic agents, are applied to the surface of plastic in an aqueous solution, the surface does not become uniformly wet. Water droplets coagulate, making it necessary to use a solvent such as alcohol in combination, resulting in an unavoidable deterioration of the working environment and the problem of requiring a large investment in equipment to recover the used solvent. In view of this point of view, the present inventors have conducted intensive research on a coating type antistatic agent that is completely water-soluble, easy to prepare an aqueous solution and apply, and has an excellent antistatic effect.
Surprisingly, by blending the J water-soluble acrylic resin with polyoxyethylene sorbitan fatty acid ester and/or N-hydroxyethyl-N-hydroxyalkylamine, the poor solubility of the water-soluble acrylic resin in water is resolved. At the same time, the wettability of polyoxyethylene sorbitan fatty acid ester and N-hydroxyethyl-N-hydroxyalkylamine to the plastic surface is improved, and it can be coated with a roll coater, spray, etc. in a completely aqueous solution state without using any solvents such as alcohol. We have discovered that it is possible to uniformly apply the coating to the surface of plastic by a method, and that it can also exhibit a good antistatic effect or an excellent antifogging effect even after thermoforming such as vacuum forming. This invention has been achieved.

That is, the present invention provides a coating type antistatic agent for plastics containing a water-soluble acrylic resin, polyoxyethylene, sorbitan fatty acid ester, and/or N-hydroxyethyl-N-hydroxyalkylamine.

In the present invention, the water-soluble acrylic resin is polyacrylic acid obtained by hydrolyzing polymethyl acrylate with an alcoholic alkali, or by polymerizing acrylic acid monomers, its sodium salt or ammonium salt, or a lower alcohol. , copolymerizing a monomer having an acid group such as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and an acrylic ester or methacrylic ester in a hydrophilic organic solvent such as dioxane in the presence of a conventional polymerization catalyst, Examples include polymers in which the acid groups in the polymer are neutralized with a base.

Further, the water-soluble acrylic resin may be of the amphoteric ion type or the positive ion type, but is preferably of the amphoteric ion type. This water-soluble acrylic resin is preferably an aqueous solution with a concentration of 10 to 4% by weight (
Examples include amphoteric ion type or positive ion type acrylic water-soluble resins which are commercially available as antistatic agents (containing some alcohols). The polyoxyethylene zorbitan fatty acid ester used in the present invention is preferably an ester of a fatty acid having 12 to 18 carbon atoms.
In addition, N-hydroxyethyl-N-hydroxyalkylamine is represented by the following general formula, and n
is preferably 8 to 18.

General formula: Polyoxyethylene sorbitan fatty acid ester and N-hydroxyethyl-N-hydroxyalkylamine are usually commercially available in the form of a solution such as an aqueous solution, so it is advantageous to use this.

The blending ratio of polyoxyethylene, sorbitan fatty acid ester and/or N-hydroxyethyl-N-hydroxyalkylamine to the water-soluble acrylic resin is 90 to 1 part by weight per 10 to 90 parts by weight of the water-soluble acrylic resin, Preferably, the amount is 30-5 parts by weight and 70-5 parts by weight.

The antistatic agent of the present invention combines both polyoxyethylene/zorbitan fatty acid ester and N-hydroxyethyl-N-hydroxyalkylamine with a water-soluble acrylic resin, or polyoxyethylene/zorbitan fatty acid ester, or N-hydroxyethyl-N-hydroxyalkylamine. - It can be obtained by stirring and mixing either one of the hydroxyalkylamines and the water-soluble acrylic resin with a predetermined amount of water.

In this case, a small amount of alcohol or the like may be added as necessary to promote dissolution. In addition, other drugs such as stabilizers may be present as necessary. In addition, water-soluble acrylic resin, polyoxyethylene, sorbitan fatty acid ester, or N-hydroxyethyl-N
- When a commercially available solution is used as the hydroxyalkylamine, the components contained therein are naturally present. In this case, the concentration should be considered when determining the mixing ratio. Furthermore, the concentration of the antistatic agent of the present invention can be made higher than the concentration at the time of use, and it can be diluted at the time of use. It is appropriate that the total concentration of N-hydroxyethyl-N-hydroxyalkylamine is about 0.03 to 5% by weight. Note that it is also possible to dilute the water-soluble acrylic resin, polyoxyethylene sorbitan fatty acid ester and/or N-hydroxyethyl-N-hydroxyalkylamine to a predetermined concentration in advance, and then mix these together; however, these may be used alone. It is extremely difficult to dilute with water. Therefore, it is preferable to dilute with water in a state in which the water-soluble acrylic resin and the polyoxyethylene solbitan fatty acid ester and/or the N-hydroxyethyl-N-hydroxyalkylamine coexist. The antistatic agent of the present invention thus obtained can be applied to the surface of plastic by conventionally known means, and if necessary, it can be further diluted with water to form a dilute aqueous solution.
This is done using a printing machine, roll coater, spray, etc.

Examples of plastics that can be treated with the antistatic agent of the present invention include transparent synthetic resins such as general-purpose polystyrene, high-impact polystyrene, polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, and polymethyl methacrylate. These examples include, but are not limited to. Furthermore, the preferred form for application is a transparent film or sheet. The antistatic agent according to the present invention not only can be uniformly applied to the surface of plastic molded products in the form of an aqueous solution without using a solvent such as alcohol, but also has excellent antistatic effects on plastics. It shows excellent anti-fog effect.

This effect persists even after thermoforming such as vacuum forming. Furthermore, when applied to a transparent film, it imparts an excellent antistatic effect or an excellent antifogging effect in addition to the antistatic effect without causing blocking or impairing transparency. Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A commercially available amphoteric ionic water-soluble acrylic resin (product name: YUKAST-1000, manufactured by Mitsubishi Yuka Co., Ltd.) and a commercially available polyoxyethylene sorbitan fatty acid ester having a carbon number of 12 to 18 (product manufactured by Matsumoto Yushi Confectionery Co., Ltd.) Name:゛m-10
9) were allowed to coexist in water and mixed by stirring.

The obtained antistatic agent has a water-soluble acrylic resin equivalent to 0.0% as a pure product. It was an aqueous solution containing 0.45% by weight of polyoxyethylene sorbitan fatty acid ester and a trace amount of alcohol derived from the raw materials.

Example 2 Water-soluble acrylic resin used in Example 1 and carbon 8~
18 N-hydroxyethyl-N-hydroxyalkylamine (product name: Dasper 125, manufactured by Miyoshi Yushi Co., Ltd.)
BS) were allowed to coexist in water and mixed by stirring.

- The obtained antistatic agent is a water-soluble acrylic resin with 0. It was an aqueous solution containing 0.45% by weight of N-hydroxyethyl-N-hydroxyalkylamine and a trace amount of alcohol derived from the raw materials.

Test Example 1 A transparent impact-resistant polystyrene, which is a styrene-butadiene block copolymer with a styrene content of 75% by weight and a butadiene content of 25% by weight, was used to achieve a thickness of 0.5 Tfr! n
A sheet was formed, and on the surface of this sheet, the antistatic agents of Examples 1 and 2 above were added, as well as the water-soluble acrylic resin aqueous solution used as a raw material in each of the above Examples as a comparative example.
Polyoxyethylene with 12 to 18 carbon atoms, zorbitan fatty acid ester, and N-hydroxyethyl-N-hydroxyalkylamine with 8 to 18 carbon atoms are each diluted with water to 0.
．． A 75% by weight aqueous solution was prepared and applied to the surface of the sheet to a thickness of 20μ using a percoater.

This sheet was vacuum formed into a cup shape at 130°C. Two points (
The half-life of the honest meter was measured using a static honest meter (manufactured by Shishido Shokai) at two points (points a and b) and two points on the bottom wall (points c and d) to determine the antistatic property. 70 hot water was poured into the beaker, the top of the beaker was covered with the molded product, and the degree of cloudiness at each point A, b, c, and d was examined. The results are shown in Table 1, and the antistatic agents of Examples 1 and 2 of the present invention were superior to the comparative examples in both honest meter half-life and degree of cloudiness. It was found that the antistatic effect and antifogging effect were exhibited. Test Example 2 Using the high impact polystyrene used in Test Example 1, a thickness of 3
A film of 0μ was formed, and 2 of each drug used in Test Example 1 was formed.
Coat the weight% aqueous solution to a thickness of 5μ with a percoater, dry with hot air, then overlap the coated sides of the film with each other and apply a 50g
/CFlf was applied and left at 23°C for 2 hours, and the state of blocking on the contact surface was examined.

Claims (1)

[Claims] 1 Water-soluble acrylic resin and polyoxyethylene sorbitan fatty acid ester and/or N-hydroxyethyl-
A coating type antistatic agent for plastics, characterized by containing N-hydroxyalkylamine. 2 10 to 90 parts by weight of water-soluble acrylic resin and 12 carbon atoms
~18 polyoxyethylene sorbitan fatty acid ester and/or N-hydroxyethyl having 8 to 18 carbon atoms
The coating type antistatic agent for plastics according to claim 1, which is obtained by dissolving 90 to 10 parts by weight of N-hydroxyalkylamine in water.