JPH05339559A - Antistatic agent excellent in transparency - Google Patents

Abstract

PURPOSE:To obtain an antistatic agent which is excellent in transparency and user for making a resin film for food wrapping, etc., antistaic. CONSTITUTION:The title agent comprises a synthetic hectorite clay mineral contg. 1.0-10.0wt.% sodium pyrophosphate, an acrylic or polyolefin-based soap- free emulsion, and a surfactant of an acetylene glycol type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antistatic agent for a resin film, such as a food packaging material for packaging confectionery and fresh food, or a general packaging film, in which transparency is important.

[0002]

2. Description of the Related Art Generally, polymer products such as resin films have a volume resistivity of more than 10 ¹³ Ωcm and a surface resistivity of more than 10 ¹³ Ω. This is one of the features of the product. This feature has greatly contributed to the expansion of demand for polymer products, but on the other hand, it causes electrostatic damage due to electrification. Once static electricity is generated due to friction, etc., it is difficult for the static electricity to escape to the outside due to its electrical insulation properties, and it accumulates, causing various problems. For example, in food packaging materials, dust and dirt are attached during the display, and the value of the product is remarkably reduced in appearance. In order to prevent such problems, a method of kneading or applying various surfactants to a resin is generally practiced (CMC Publishing, Fine Chemicals, "Antistatic Materials Recent Market Trends (1)" Vol. 1).
6, No. 15, P24-P36, (1987)).

However, among the above-mentioned various surfactants, the anionic and nonionic surfactants generally have a surface specific resistance level of 10 ¹² Ω or more regardless of the kneading method or the coating method, and sufficient antistatic property is obtained. No effect has been obtained.

Further, cationic surfactants and amphoteric surfactants are not preferable because many substances suspected of being carcinogenic may affect the human body.

On the other hand, there is also known a method of applying colloidal silica or alumina aqueous solution, a purified product of natural clay or the like on the surface.

However, the resin film coated with these inorganic compounds on the surface has a problem that the adhesiveness is poor and uniform surface coating is difficult. In addition, in order to apply it to the resin film, it is indispensable to use it together with a surfactant due to the problem of cissing, and its poor compatibility causes aggregation and sedimentation over time, resulting in poor workability and deterioration of transparency due to aggregation. Therefore, it is inconvenient to process a transparent organic film.

As described above, as an antistatic agent for a transparent organic film, an antistatic agent excellent in antistatic effect, adhesiveness and transparency has not yet been obtained, and such an antistatic agent has been strongly demanded.

[0008]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors on the production of a resin film having an excellent antistatic effect, as a result of utilizing a synthetic hectorite clay mineral containing sodium pyrophosphate, an acrylic The present invention has been completed by finding that an antistatic agent excellent in adhesiveness and transparency can be obtained by using a soap-based emulsion or a polyolefin-based soap-free emulsion as an adhesive and further using an acetylene glycol type surfactant.

The synthetic hectorite clay mineral used in the present invention has the following general formula:

[0010]

[Chemical 1]

In addition, it is composed of magnesium, silicon, sodium and trace amounts of lithium and fluorine as main components, and also contains sodium pyrophosphate. In order to obtain excellent adhesiveness, transparency, and antistatic effect, the content of sodium pyrophosphate is 1.0 to 10.0 wt% in the total components of the synthetic hectorite clay mineral, more preferably 3.0 to 8. It is 0 wt%. When the content of sodium pyrophosphate is less than the above range, the transparency and antistatic effect are poor. Further, if the content of sodium pyrophosphate exceeds the above range, the stability of the coating solution becomes poor and the coating film surface becomes poor.

The synthetic hectorite clay mineral may be used in an amount of 1 to 10 wt% in all the components of the antistatic agent according to the present invention, and the amount used may be determined according to the purpose such as antistatic effect. However, it should be noted that the concentration of 1 wt% or less makes it difficult to obtain the antistatic effect, and the concentration of more than 10 wt% causes the viscosity to increase sharply and the workability to deteriorate.

Next, as the adhesive to be used, acrylic and polyolefin soap-free emulsions are preferably used for the purpose of obtaining excellent transparency. These acrylic soap-free emulsions also include acrylic acid ester homopolymers, copolymers of acrylic acid esters and methacrylic acid esters, vinyl acetate, styrene, acrylonitrile, acrylic acid, and the like.
Further, among the polyolefin-based soap-free emulsions, ethylene vinyl acetate copolymer emulsion, ethylene acrylic acid copolymer, ionomer and the like are also included. Acrylic and polyolefin soap-free emulsions as an adhesive can be mixed in a wide range and may be used according to the intended adhesive strength, but usually 5.0 to 50 wt% of all components is used. preferable.

Acrylic emulsion containing emulsifier or carboxymethyl cellulose (CM
The use of other water-soluble resins such as C) and polyvinyl alcohol may be inferior in performance such as transparency, adhesiveness and antistatic property, which is not preferable.

Further, as the surfactant in the present invention, an acetylene glycol type surfactant is used because of its excellent cissing prevention effect and excellent system stability. This acetylene glycol type surfactant is a series of compounds having an acetylene bond and an alcoholic hydroxyl group in the molecule and also includes an adduct such as ethylene oxide. Since such an acetylene glycol type surfactant is added for the purpose of preventing cissing that occurs when the antistatic agent is applied to the resin film, the addition amount may be the minimum necessary amount and may be 0.1 to 5 wt% of all components.

Other nonionic surfactants and anionic surfactants are not preferable because they may cause problems such as increase in viscosity and formation of precipitates over time.

Cationic surfactants and amphoteric surfactants are not preferable because many substances suspected to have carcinogenic effects on the human body are unfavorable and they also cause dispersion inhibition of synthetic hectorite clay minerals. It cannot be used.

[0018]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The coating on the organic film and the measurement of electrical characteristics and transmittance were carried out according to the following methods. (Applying to organic film, drying) An appropriate amount of the adjusted antistatic agent was dropped onto the organic film to obtain a uniform coating film having a thickness of about 2.5 μm. After coating with a 5-bar coater, the test piece was dried at room temperature.

(Measurement of electrical characteristics) 4329A HIGH
The surface resistivity was measured using a RESISTANCE METER (manufactured by Yokogawa Hewlett-Packard Co.).

(Measurement of Transmittance) An MSC-CH colorimeter (manufactured by Suga Test Co., Ltd.) was used to measure the transmittance. As the measuring method, the transmittance when the organic film was stuck on the glass plate as a blank was set to 100%, and then the test piece was stuck on the glass plate and the same operation was performed to measure the transmittance.

(Measurement of Adhesiveness) Rubber Peeling Test (JIS
Based on K6301-1964), the pedestrian test was carried out. Commercially available cellophane tape (manufactured by Nitto Cellophane Co., Ltd.) 7.5 cm x 5.0 cm was attached to the coating surface of the test piece using a roller, peeled at 90 °, and the torque applied at that time was measured. The adhesive strength was calculated.

Tf = F / b Tf: Adhesive strength (kg / cm) F: Peeling load (kg) b: Width of test piece (cm) Adhesive strength of 100 g / cm or more; Adhesiveness: rated as x.

(Coating state) The coating state was visually observed to evaluate the dispersion state, coating surface and the like.

(Stability of coating liquid) Leave at room temperature for 30 days,
The state of the coating liquid was visually observed.

Example 1 A synthetic hectorite clay mineral containing 90 parts by weight of water and 6 wt% of sodium pyrophosphate (trade name: Laponite S: Lapor)
te Industries Ltd. 10 parts by weight, acrylic soap-free emulsion (trade name Almatex E-269: manufactured by Mitsui Toatsu Chemicals, Inc.) 30 parts by weight, acetylene glycol type surfactant (trade name Surfynol 440: manufactured by Nisshin Chemical Co., Ltd.) 1 part by weight was sufficiently agitated and mixed by a high speed mixer to prepare a coating solution, which was then coated on a PP film according to the coating method described above to prepare a test piece, and various evaluation tests were carried out. The results are shown in Table 1.

Example 2 Instead of the water-soluble acrylic emulsion used in Example 1, a polyolefin emulsion (trade name: Chemipearl S-100: manufactured by Mitsui Petrochemical Co., Ltd.) was used, and the test piece was then subjected to the same conditions. Then, various evaluation tests were carried out. The results are shown in Table 1.

Example 3 The compounding amount of the synthetic hectorite clay mineral used in Example 1 was changed to 5 parts by weight, and thereafter, test pieces were obtained under the same conditions and various evaluation tests were carried out. The results are shown in Table 1.

Example 4 The synthetic hectorite clay mineral containing 9% of sodium pyrophosphate was used in Example 1, and thereafter a test piece was obtained under the same conditions and various evaluation tests were carried out. The results are shown in Table 1.

Example 5 The amount of the water-soluble acrylic emulsion used in Example 1 was changed to 50 parts by weight, and thereafter a test piece was obtained under the same conditions, and various evaluation tests were carried out. The results are shown in Table 1.

Comparative Example 1 A test piece was prepared under the same conditions except that the synthetic hectorite clay mineral of Example 1 was omitted, and the same test as in Example 1 was carried out. The comparison results are shown in Table 1. It was

Comparative Example 2 A test piece was obtained with the same composition as in Example 1 except that the acrylic soap-free emulsion was removed, and then the same conditions were used.
The same test as in Example 1 was performed and the results of comparison are shown in Table 1.

Comparative Example 3 A test piece was obtained under the same conditions as in Example 1 except that the acetylene glycol type surfactant was removed, and the same test as in Example 1 was carried out. It was shown to.

Comparative Example 4 Laponite B (Laporte Industries L) was used as a synthetic hectorite clay mineral with the composition of Example 1.
td. Made: does not contain sodium pyrophosphate),
Other operations were performed in the same manner to obtain a test piece, the same test as in Example 1 was performed, and the comparison results are shown in Table 1.

Comparative Example 5 A synthetic hectorite clay mineral containing 15 parts by weight of sodium pyrophosphate was used as the synthetic hectorite clay mineral in the composition of Example 1, and other operations were carried out in the same manner to obtain a test piece, and the test was carried out. The same test as in Example 1 was performed and the results of comparison are shown in Table 1.

Comparative Example 6 Instead of the acrylic soap-free emulsion in the formulation of Example 1, an emulsifier-containing acrylic emulsion (Boncoat EC-100, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) was used, and other operations were performed in the same manner. The test pieces were obtained, the same tests as in Example 1 were performed, and the results of comparison were shown in Table 1.

Comparative Example 7 The composition of Example 1 was replaced by CMC (1% aqueous solution) (trade name CMC128) instead of the acrylic soap-free emulsion.
(0: manufactured by Daicel Chemical Industries, Ltd.) and other operations were performed in the same manner to obtain a test piece, and the same test as in Example 1 was performed and the results of comparison are shown in Table 1.

Comparative Example 8 PVA (5% aqueous solution) (trade name PVA (polymerization degree 500): manufactured by Kishida Chemical Co., Ltd.) was used in place of the acrylic soap-free emulsion in the formulation of Example 1, and other operations were the same. Table 1 shows the comparison results obtained by performing the same test as in Example 1 to obtain a test piece.

Comparative Example 9 A nonionic lauryl ether type surfactant (trade name: Nonion P208, manufactured by NOF CORPORATION) was used as a surfactant in the formulation of Example 1, and other operations were carried out in the same manner to prepare a test piece. The same tests as in Example 1 were performed and the results of comparison were shown in Table 1.

Comparative Example 10 An anionic surfactant (sodium lauryl sulfate) was used as a surfactant in the formulation of Example 1, and other operations were performed in the same manner to obtain a test piece, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 11 In the formulation of Example 1, a cationic surfactant (trade name: Kotamine 24P: manufactured by Kao Corporation) was used as a surfactant, and other operations were performed in the same manner to obtain a test piece. The same test as in Example 1 was conducted and the results of comparison are shown in Table 1.

Comparative Example 12 A natural bentonite refined product (trade name: Kunipia F: manufactured by Kunimine Industry Co., Ltd.) was used in place of the synthetic hectorite clay in the composition of Example 1, and other operations were performed in the same manner to obtain a test piece. The same test as in Example 1 was performed and the results of comparison are shown in Table 1.

[0042]

[Table 1]

[0043]

As is apparent from the above description, according to the present invention, it is possible to provide an antistatic agent which gives a resin film a sufficient antistatic effect and is excellent in adhesiveness and transparency. ..

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshikazu Fukunaga 76-3 Oshima, Tokuyama City, Yamaguchi Prefecture

Claims (1)

[Claims] 1. Sodium pyrophosphate is 1.0 to 10 wt.
%, An antistatic agent having excellent transparency, which comprises a synthetic hectorite clay mineral, an acrylic or polyolefin soap-free emulsion, and an acetylene glycol type surfactant.