JP2008031398A - Antistatic agent composition for coating and method for producing antistatic resin molded article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic agent composition for coating, which is high in safety and hardly deteriorates the antistatic property under low humidity, and to provide a method for producing an antistatic resin molded article using the composition. <P>SOLUTION: This antistatic agent composition for the coating comprises an anionic surfactant (A) having a 8 to 20C alkyl group and a lower multi-functional alcohol (B) as essential components, wherein a weight ratio ((A)/(B)) is in a range of 60/40 to 95/5. The method for producing the antistatic resin molded article includes a process for coating the surface of a resin molded article with the antistatic agent composition for the coating. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antistatic agent composition for coating that exhibits good antistatic properties even under low humidity and has high safety, and a method for producing an antistatic resin molded article using the same.

  Thermoplastic resins are used in various applications because of their good processability. These resins are generally highly insulating and are used for various purposes by utilizing this excellent property. However, static electricity is likely to be generated due to friction, and the generated static electricity accumulates (charges). It causes various troubles such as shocks to the human body, dirt on molded products by collecting dust in the air, and electrical disturbances to electrical equipment. In order to prevent these troubles, in general, a surface active agent is used to change the electrostatic physical properties of the surface of the molded product, thereby providing an antistatic property. Specific examples include a method of applying an antistatic agent containing a surfactant to the surface of a molded product, a method of kneading an antistatic agent in advance at the time of forming a molded product, and the like.

  In the method of kneading the antistatic agent, it is thought that the antistatic agent migrates (orientates) sequentially to the surface and forms an electrically conductive film on the surface of the molded product. There is a problem in the immediate effect of the effect, not immediately afterwards. Further, when the antistatic agent is kneaded, heating at a temperature equal to or higher than the resin melting temperature is required. For these reasons, for high melting point resins such as polyester, a method of applying an antistatic agent to the surface of a molded product has been mainly performed.

  Among the applications of thermoplastic resins, food-related containers and packaging applications are listed as main applications. However, even for surfactants, cationic surfactants and amphoteric surfactants have a problem that they are difficult to use in food applications because of concerns about safety. Further, the nonionic surfactant has a problem that its antistatic performance itself is low. Therefore, anionic surfactants have been mainly used in food related applications. However, with anionic surfactants, a decrease in antistatic performance is always a problem at low humidity.

Several proposals have been made as measures for preventing the performance deterioration of the antistatic agent under low humidity (see Patent Documents 1 to 3). However, even if performance degradation under low humidity is prevented, these are all proposals using a special polymer antistatic agent and not a proposal using a general surfactant. There is a problem that it cannot be used in applications where safety is essential. As described above, there is no suitable antistatic agent for coating that has high safety and does not deteriorate the antistatic property under low humidity, and its development is required.
JP 2000-328046 A JP 2002-88180 A Japanese Patent No. 3272996

  An object of the present invention is to provide an antistatic agent composition for coating that is highly safe and whose antistatic property is less likely to deteriorate under low humidity, and a method for producing an antistatic resin molded product using the same. is there.

  As a result of intensive research, the present inventors have found that in general antistatic agents for coating containing an anionic surfactant, (1) moisture in the air is formed on the surface of the molded product as an antistatic action mechanism. The anionic surfactant is collected on the coating film, and the conductive layer is formed on the coating film to leak charges, thereby exhibiting antistatic properties. (2) In particular, the moisture content in the air ( The knowledge that (humidity) has a great influence on the antistatic performance was obtained. The inventors of the present invention provide an antistatic agent composition obtained by blending a specific anionic surfactant and a lower polyfunctional alcohol at a specific ratio, and has high safety and performance under low humidity. The present invention was reached after confirming that there was little decrease.

That is, the antistatic agent composition for coating according to the present invention contains an anionic surfactant (A) having an alkyl group having 8 to 20 carbon atoms and a lower polyfunctional alcohol (B) as essential components, and each weight The ratio ((A) / (B)) is in the range of 60/40 to 95/5.
The manufacturing method of the antistatic resin molded article concerning this invention includes the process of apply | coating the said antistatic agent composition for application | coating to the surface of a resin molded article.

The antistatic agent composition for coating of the present invention exhibits good antistatic properties even at room temperature and normal humidity, has high safety, and does not easily deteriorate antistatic properties at low humidity.
In the method for producing an antistatic resin molded product of the present invention, an antistatic resin molding that exhibits good antistatic properties even at room temperature and humidity, and that is highly safe and hardly deteriorates in antistatic properties at low humidity. The product can be manufactured efficiently.

  The antistatic agent composition for coating of the present invention is an antistatic agent that is usually used by applying to the surface of a resin molded product, but it may be used by kneading it in advance in a resin molding material. The antistatic agent composition for coating is a composition containing an anionic surfactant (A) and a lower polyfunctional alcohol (B) as essential components.

[Anionic surfactant (A)]
The anionic surfactant (A) used in the present invention has an alkyl group having 8 to 20 carbon atoms. The anionic surfactant (A) is a component that exhibits excellent antistatic properties in the antistatic agent composition for coating of the present invention, and the antistatic agent composition for coating of the present invention is used in food containers and packaging materials. High safety when used for the above. In the anionic surfactant, the alkyl group is essential for maintaining good adhesion to the resin and the surface condition of the molded product after drying the coating agent. And when carbon number of an alkyl group is 8-20, a surface state is favorable.

  Examples of the alkyl group having 8 to 20 carbon atoms constituting the anionic surfactant (A) include octyl group, nonyl group, decyl group, tridecyl group, and octadecyl group. If the alkyl group has less than 8 carbon atoms, the surface may be sticky because the hydrophilicity is too strong. On the other hand, when the carbon number of the alkyl group exceeds 20, the surface becomes hard due to strong hydrophobicity, and problems such as whitening of the surface of the resin molded product and peeling of the coating agent may occur.

The anionic surfactant (A) is preferably a compound containing in the molecule at least one functional group selected from a sulfonic acid (salt) group, a sulfate ester (salt) group and a phosphate ester (salt) group. .
Here, the sulfonic acid (salt) group is a sulfonic acid group (—SO ₃ H), or a proton of the sulfonic acid group is a metal atom (an alkali metal or alkaline earth metal such as lithium, sodium, or potassium) or ( Substitution) means a sulfonate group substituted with an ammonium group or the like. The sulfate ester (salt) group is an esterified product of sulfuric acid and a compound having a hydroxyl group, or the proton of the esterified product is a metal atom (alkali metal or alkaline earth metal such as lithium, sodium or potassium) or (substituted) ) A sulfate group substituted with an ammonium group or the like. Furthermore, the phosphoric acid ester (salt) group is an esterified product of phosphoric acid and a compound having a hydroxyl group, or the proton of the esterified product is a metal atom (alkali metal or alkaline earth metal such as lithium, sodium or potassium) or (substituted) ) A phosphate ester group substituted with an ammonium group or the like.

  Examples of the compound containing a sulfonic acid (salt) group in the molecule include octyl sulfonic acid, dodecyl sulfonic acid, tridecyl sulfonic acid, octyl sulfonic acid Na salt, sodium dodecyl sulfonate, sodium tridecyl sulfonate, octyl benzene sulfone. Acid, dodecylbenzenesulfonic acid, tridecylbenzenesulfonic acid, sodium octylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium tridecylbenzenesulfonate, sodium salt of dioctylsulfosuccinate, sodium salt of ditridecylsulfosuccinate, octyl Examples include sodium phenyl ether sulfonate, sodium nonyl phenyl ether sulfonate, sodium dodecyl diphenyl ether disulfonate, and the like.

  Examples of the compound containing a sulfate (salt) group in the molecule include ammonium salt of dodecyl sulfate, ammonium salt of POE (5) dodecyl alcohol ether sulfate, ammonium salt of POE (10) dodecyl alcohol ether sulfate, POE (5 ) An ammonium salt of octylphenyl ether sulfate, an ammonium salt of POE (10) octylphenyl ether sulfate, an ammonium salt of POE (5) nonylphenyl ether sulfate, an ammonium salt of POE (10) nonylphenyl ether sulfate, and the like.

  Examples of the compound containing a phosphate (salt) group in the molecule include POE (5) octyl phosphate, POE (10) octyl phosphate, POE (5) dodecyl phosphate, POE (10) dodecyl phosphate, POE (5) tridecyl phosphate. POE (10) tridecyl phosphate, POE (5) octyl phosphate sodium salt, POE (10) octyl phosphate sodium salt, POE (5) dodecyl phosphate sodium salt, POE (10) dodecyl phosphate sodium salt, POE (5) sodium salt of tridecyl phosphate, sodium salt of POE (10) tridecyl phosphate, POE (5) octyl phenyl ether phosphate, POE (10) octyl phenyl ether phosphate, P E (5) nonylphenyl ether phosphate, POE (10) nonylphenyl ether phosphate, sodium salt of POE (5) octylphenyl ether phosphate, sodium salt of POE (10) octylphenyl ether phosphate, POE (5) nonylphenyl ether phosphate And the sodium salt of POE (10) nonylphenyl ether phosphate.

  These anionic surfactants (A) may be used alone or in combination of two or more. In the above, POE (n) means “polyoxyethylene having n repeating units”.

[Lower polyfunctional alcohol (B)]
The lower polyfunctional alcohol (B) is a compound having 2 to 16 carbon atoms and having two or more hydroxyl groups in the molecule.

  The lower polyfunctional alcohol (B) is a component having high hydrophilicity and imparting hygroscopicity, and can be contained in the antistatic agent composition for coating of the present invention even when the atmosphere is under low humidity. The decrease in antistatic property of the surfactant (A) can be reduced. Of course, the lower polyfunctional alcohol (B) is also a component that acts so that the antistatic agent composition for coating of the present invention can exhibit good antistatic properties even at ordinary temperature and humidity. The lower polyfunctional alcohol (B) is also highly safe when used in food containers, packaging materials, etc., like the anionic surfactant (A).

  The lower polyfunctional alcohol (B) is not particularly limited, but at least one alcohol selected from glycerin, ethylene glycol, propylene glycol and polyethylene glycol having a molecular weight of 400 or less is preferable. On the other hand, monofunctional alcohols such as ethanol and isopropanol and polyethylene glycol having a molecular weight of more than 400 may not be able to maintain sufficient antistatic properties under low humidity due to insufficient hygroscopicity.

[Other ingredients]
In addition to the anionic surfactant (A) and the lower polyfunctional alcohol (B) described above, the components constituting the antistatic agent composition for coating of the present invention include solvents; antioxidants, ultraviolet absorbers, Examples thereof include additives such as plasticizers, pigments, dyes, and light stabilizers. It is desirable that the effect of the present invention is not impaired when the antistatic agent composition for coating of the present invention contains a solvent or an additive.

  As the above-mentioned solvent, it is easy to handle when producing the antistatic agent composition for coating of the present invention, and an antistatic resin molded article described later using the antistatic agent composition for coating of the present invention. When manufacturing the antistatic agent composition for coating, the steps of weighing, coating, drying and the like can be easily performed. Therefore, water is essential, and an organic solvent having a boiling point of 100 ° C. or lower is further included. Certain aqueous solvents (C) are preferred. In the aqueous solvent (C), water is an essential component because of the characteristics of the anionic surfactant (A) having high solubility in water. In addition, the aqueous solvent (C) preferably further contains an organic solvent having a boiling point of 100 ° C. or lower in order to improve drying properties and wettability to a molded product.

Examples of the organic solvent having a boiling point of 100 ° C. or lower include methanol, ethanol, isopropyl alcohol, methyl ethyl ketone, acetone, acetonitrile, and the like. These organic solvents may be used alone or in combination of two or more. The boiling point of the organic solvent is preferably 80 ° C. or lower, more preferably 60 ° C. or lower. When an organic solvent having a boiling point of more than 100 ° C. is used, there may be a problem that a large amount of heat is required at the time of drying or insufficient drying occurs.
The weight ratio of water in the aqueous solvent (C) is preferably 10 to 100% by weight, more preferably 50 to 100% by weight. If the weight ratio of water in the aqueous solvent (C) is less than 10% by weight, the solubility of the anionic surfactant is not sufficient, so that the stability of the whole system is impaired and separation or the like may occur.

[Ingredient ratio of ingredients]
In the antistatic agent composition for coating of the present invention, the weight ratio ((A) / (B)) of the anionic surfactant (A) and the lower polyfunctional alcohol (B) is usually 60/40 to 95 / 5, preferably in the range of 70/30 to 90/10, more preferably in the range of 75/25 to 85/15.

  When (A) / (B) is smaller than 60/40 (that is, when the weight ratio of (A) is small), the performance of the anionic surfactant (A) is not sufficiently exhibited, regardless of humidity. The antistatic property is not sufficient, and stickiness may occur when the antistatic agent composition for coating of the present invention is used. On the other hand, when (A) / (B) is larger than 95/5 (that is, when the weight ratio of (A) is large), the performance of the lower polyfunctional alcohol (B) is not sufficiently exhibited, and the humidity is low. There is a possibility that the antistatic property is lowered.

[Production method of antistatic resin molded product]
The manufacturing method of the antistatic resin molded product of the present invention is a manufacturing method including a step (application step) of applying the antistatic agent composition for coating described above to the surface of the resin molded product.
There is no limitation in particular as a resin molded product, The resin molded product which consists of arbitrary resin materials can be mentioned. Examples of resin materials include high-density polyethylene, low-density polyethylene, ethylene / α-olefin copolymers, ethylene vinyl acetate copolymers, polyolefin resins such as polypropylene and poly-1-butene; styrene, AS, and ABS resins. Styrenic resins such as polyethylene terephthalate, polybutylene terephthalate, polyester resins such as polylactic acid; polyamide resins such as 6-nylon and 6,6-nylon; heat of polycarbonate, polyvinyl chloride, mixtures thereof, etc. Examples thereof include plastic polymers; rubber materials such as natural rubber and synthetic rubber; thermosetting resins such as phenol resin and polyurethane.

The form of the resin molded product is not particularly limited, and examples thereof include various forms such as a film, a sheet, a hollow molded product, an injection molded product, a woven fabric, a nonwoven fabric, and synthetic leather.
The specific method for applying the coating antistatic agent composition to the surface of the resin molded product is not particularly limited. For example, the roll coating method, the roll brush method, the spray coating, the air knife coating, the impregnation method, and the curtain method. These methods may be combined.

There is no particular limitation on the coating amount of the antistatic agent composition for coating, but it is preferable to keep it to the minimum necessary amount because it is not economical to increase the amount unnecessarily, and it also leads to contamination of the coated surface. The antistatic agent composition for application is preferably applied in an amount of 0.005 to 0.5 g / m ² , more preferably 0.1 to 0.3 g / m ² as an active ingredient in a dry state after application. Is done. Here, the dry state is defined as a state in which the aqueous solvent (C) is completely volatilized in the antistatic agent composition for coating, and the active ingredient is left after the aqueous solvent (C) is volatilized. It means the total amount of the anionic surfactant (A) and the lower polyfunctional alcohol (B) on the coated surface.

In the method for producing an antistatic resin molded article of the present invention, a step of drying the coated surface (drying step) may be further performed after the coating step. In particular, when the antistatic agent composition for coating further contains an aqueous solvent (C), problems such as stickiness of the surface of the resulting antistatic resin molded product are eliminated, and the manufacturing process time is shortened. It is preferable to perform a drying step. The drying temperature of the resin molded product after coating is preferably 110 ° C. or higher, and the upper limit of the drying temperature varies depending on the type of resin used, but in general, the resin melting point is preferably 20 ° C. or lower. Moreover, you may dry in a heat | fever extending process after application | coating like a biaxially stretched polyester film.
Although the detailed mechanism of the phenomenon in which the antistatic property does not deteriorate even under low humidity in the present invention has not been analyzed, it is presumed as follows.

  When antistatic is performed with the anionic surfactant (A), moisture in the air is collected in a film containing the anionic surfactant (A) formed on the surface of the resin molded product, and a conductive layer is formed on the film. It is considered that charges are leaked by being formed. Here, since the anionic surfactant (A) has a particularly high hygroscopic property, it is used as a component of a coating-type antistatic agent composition. However, while its performance is high, it has a low moisture content in the air. Then, sufficient moisture cannot be obtained on the surface. On the other hand, the lower polyfunctional alcohol (B) is different from the anionic surfactant (A) in terms of molecular structure, and since there is (almost) no hydrophobic portion in the molecule, the surface of the resin molded product The film has poor adsorptivity and does not form a film. The lower polyfunctional alcohol (B) alone does not exhibit antistatic properties, but has a property of very high moisture collecting ability in the air. Thus, by blending the anionic surfactant (A) and the lower polyfunctional alcohol (B) having different properties, the hygroscopicity under low humidity was compensated while forming a film on the resin molded product. Presumed to be.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. “Parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.

(Example 1)
While stirring an aqueous sodium dodecylsulfonate solution (concentration: 40% by weight) as an anionic surfactant with a glycerin as a lower polyfunctional alcohol so that the weight ratio of sodium dodecylsulfonate / glycerin is 90/10. Mixed. Subsequently, water was further added to the obtained mixture so that the total concentration of sodium dodecyl sulfonate and glycerin was 40% by weight to obtain an antistatic agent aqueous solution. The obtained antistatic agent aqueous solution was dissolved in a water-isopropyl alcohol mixed solvent (mixing weight ratio 1: 1) to prepare a diluted solution having a total concentration of sodium dodecyl sulfonate and glycerin of 0.5% by weight. Using a bar coater so that the applied amount of sodium dodecyl sulfonate and glycerin is 0.01 mg / m ² as an active ingredient after drying, the obtained diluted solution was applied to a corona-treated polyester film, immediately after It dried for 5 minutes with a 110 degreeC dryer. The obtained coated film was stored for 1 day in an environment of a temperature of 23 ° C. and a humidity of 50% RH, and then allowed to stand for 3 hours or more under the measurement temperature and humidity conditions shown in Table 2. About the dry coating film obtained after standing, the surface resistivity was measured using super insulation meter SM-8310 type (manufactured by Toa Denpa Kogyo Co., Ltd.). The results are shown in Table 2.

(Examples 2 to 7)
In Example 1, except that the anionic surfactant and the lower polyfunctional alcohol were changed to the types and blending amounts shown in Table 1, the surface resistivity of the obtained dry coated film was determined in the same manner as in Example 1. It was measured. The results are shown in Table 2, respectively.

(Comparative Examples 1-3)
The surface resistivity of the comparative dry coated film obtained in the same manner as in Example 1 except that the anionic surfactant and the lower polyfunctional alcohol were changed to the types and amounts shown in Table 1 in Example 1. Was measured. The results are shown in Table 2, respectively.

ポリエチレングリコールの分子量は２００である。
括弧内に示す量は、アニオン性界面活性剤および低級多官能アルコールそれぞれの配合量である。

The molecular weight of polyethylene glycol is 200.
The amount shown in parentheses is the amount of each of the anionic surfactant and the lower polyfunctional alcohol.

  In Examples 1 to 7, even when the humidity decreases, the surface resistivity increases by an order of magnitude, and the decrease in antistatic property is small. On the other hand, in Comparative Example 1 in which no lower polyfunctional alcohol is used and in Comparative Example 3 in which the amount of lower polyfunctional alcohol is small, the surface resistivity increases by three orders of magnitude when the humidity decreases, and the antistatic property increases. Decrease significantly. In Comparative Example 2 in which the amount of the lower polyfunctional alcohol used is too large, the decrease in antistatic property due to a decrease in humidity is small, but the surface resistivity is high in the first place, and the antistatic property is low regardless of the humidity.

Claims (5)

  An anionic surfactant (A) having an alkyl group having 8 to 20 carbon atoms and a lower polyfunctional alcohol (B) are included as essential components, and the respective weight ratios ((A) / (B)) are 60/40 to An antistatic composition for coating, in the range of 95/5.   The anionic surfactant (A) is a compound containing in the molecule at least one functional group selected from a sulfonic acid (salt) group, a sulfate ester (salt) group, and a phosphate ester (salt) group. The antistatic agent composition for coating according to claim 1.   The antistatic agent composition for coating according to claim 1 or 2, wherein the lower polyfunctional alcohol (B) is at least one alcohol selected from glycerin, ethylene glycol, propylene glycol and polyethylene glycol having a molecular weight of 400 or less. object.   The antistatic agent composition according to any one of claims 1 to 3, further comprising an aqueous solvent (C) which essentially contains water and may further contain an organic solvent having a boiling point of 100 ° C or lower.   The manufacturing method of an antistatic resin molded article including the process of apply | coating the antistatic agent composition for application | coating in any one of Claims 1-4 on the surface of a resin molded article.