JPS6146013B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyolefin resin composition having excellent antistatic properties under low humidity conditions. Although films, sheets, and other molded products made from polyolefin resins are relatively inexpensive, they have advantages such as excellent mechanical properties, chemical resistance, heat resistance, transparency, and electrical insulation properties. Because
It is frequently used in a wide range of applications, including molded products, films, sheets, and fibers. However, this resin
Although it has the above advantages, its large electrical resistance makes the surface of the product easily charged, and this property
In some cases, this may cause disadvantages such as dust adhesion to the product, resulting in a decrease in product value, deterioration of workability, and the formation of whiskers due to ink scattering during printing, and in some cases, electrostatic charge may cause electric shock to the human body or sparks. , there is a risk that it may lead to a dangerous disaster. Although polyolefin resin itself is very useful, it still has drawbacks in terms of practicality and safety, and many studies have already been carried out to improve the charging property that is the cause of this problem. A number of methods are known, including methods of kneading conductive substances such as metal powder, and methods of coating or kneading various surfactants. However, conventionally known antistatic agents are effective under medium to high humidity conditions of 60% RH or higher, but they are effective during abnormally dry winters and at low humidity when used for packaging moisture-absorbing products. There is nothing that is sufficiently effective under these conditions. However, metal salts of alkylimidazoline type amphoteric surfactants (Kokagaku Shi, 68, 2213 ('65) and the same magazine, 69, 154 ('
66), but when kneaded and used,
A sufficient effect cannot be obtained, and the slip property is also insufficient. Therefore, as a result of repeated research into antistatic agents that have excellent antistatic effects on polyolefin resins under low humidity conditions and also have excellent resin surface properties, the inventors have surprisingly discovered that they can be used for kneading in themselves. It has been found that when N-acyl sarcosinate, which is ineffective as an antistatic agent, is used in combination with higher fatty acid polyhydric alcohol ester, it has excellent antistatic ability against polyolefin resins at low humidity.
The present invention is based on this discovery, and the gist of the invention is to blend a certain proportion of a mixture of N-acyl sarcosinate and higher fatty acid polyhydric alcohol ester into a polyolefin resin. . According to the present invention, it can be used not only under medium humidity conditions of around 60% RH, but also at 30% RH, which was difficult with conventional antistatic agents.
A resin composition with excellent antistatic properties can be obtained even under low humidity conditions such as RH and even 15% RH. moreover,
This resin composition does not cause whitening and has excellent slip resistance, blocking resistance, and heat resistance.
It also has excellent surface properties, such as good antifogging effects. Due to these features, the composition of the present invention exhibits its characteristics during abnormal dryness in winter and in production processing steps under dry conditions. Furthermore, since the compounds used in the composition of the present invention are non-toxic,
It can also be applied to food packaging. N-acyl zircosinate, which is a component of the composition of the present invention, can be prepared using the Schotten-Bauman method (C).
Schotten, Ber. 17, 2544 (1884) and E.
Baumann, Ber. 19, 3218 (1886)), it is an amino acid type double-active compound obtained by reacting an alkaline aqueous solution of sarcosine with a fatty acid chloride, and is represented by the general formula below. In the above formula, R ₁ is a linear alkyl group or alkenyl group having 6 to 22 carbon atoms or having a side chain, and M is a metal ion or a hydrogen atom. Incidentally, the types of metals for M include Li,
Na, K, Ca, Mg, Ba, Al, Zn, and Mn are suitable, with Na, K, Ca, or Mg being particularly preferred when the composition is used as a food packaging film. In the composition of the present invention, N-acyl sarcosinate () must be used in combination with higher fatty acid polyhydric alcohol ester () as an antistatic component. The mixing ratio of components () and () is in the range of 3:97 to 90:10 by weight, but the preferred range is 5:95 to 80:20. If () is above the upper limit, no synergistic effect will be observed, and if it is below the lower limit, whitening will occur. The total amount of both components added to the polyolefin resin is 0.03 to 3% by weight, but preferably
It is 0.05-2%. If it is less than 0.03%, good antistatic effect cannot be obtained, and even if it is added more than 3%, the antistatic effect will no longer be improved rapidly, or rather it will not only deteriorate the physical properties but also increase the cost. It gets expensive. Both components (,) can be blended into the polyolefin resin by either adding each component individually or melting and mixing both components in advance and then adding them, but the latter method is preferable. This is a more preferable addition method because it is easier to obtain an intimate mixing state and therefore the synergistic effect is superior. In addition to both components, antioxidants, ultraviolet absorbers, pigments, inorganic fillers, etc. can be optionally blended depending on the purpose and necessity. The other component of the composition of the present invention is an ester of higher fatty acid and polyhydric alcohol. Here, the polyhydric alcohol is divalent to hexavalent, such as propylene glycol, glycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, sorbide, etc., but the most preferred is glycerol. . Suitable higher fatty acids are saturated or unsaturated ones with straight or side chains of 12 to 22 carbon atoms; those with C ₁₂ or less are undesirable because they emit smoke during molding, and those with C ₂₂ or more are not effective. It is insufficient. The polyolefin resin which is the main component of the composition of the present invention is generally an aliphatic polyolefin compound, such as low density or high density polyethylene, polypropylene, poly(methylpentene-1), polybutene-1, polypentene-1, poly( 3-methyl-1-butene), but other cyclic polyolefin compounds such as polystyrene, poly-
(α-methylstyrene) and copolymers of these monomers or prepolymers. All known methods that can be used for molding polyolefin resins, such as press molding, injection molding, extrusion molding, and powder molding, can be applied to the composition of the present invention. If it is necessary to improve the printability of the molded article, corona discharge treatment, flame treatment, ozone treatment, or chromic acid treatment, which are widely used for known polyolefin resin compositions, may be applied. N-acyl sarcosinate, which is one of the antistatic components in the composition of the present invention, is known as an antistatic agent for food packaging (CFR178-3130) and an antistatic agent for photographic light-sensitive materials (Japanese Patent Publication No. 53-31470). However, according to studies conducted by the present inventors, although this compound is effective for external application, it is insufficiently effective as an antistatic agent for kneading, and furthermore, it has the disadvantage of causing a whitening phenomenon. Furthermore, the polyhydric alcohol ester of higher fatty acid, which is the other antistatic component in the composition of the present invention, has insufficient antistatic effect when used alone.
If a large amount is added to improve the effect, a whitening phenomenon (blooming) due to bleeding cannot be avoided. As mentioned above, it is completely unexpected that the combination of two components, which are relatively inferior in terms of effectiveness when used alone, would produce the excellent synergistic effect described above. The reason for this can be thought of as follows. First, in order for a kneaded antistatic agent to be effective, it is essential that it migrate to the surface by micro-Brownian motion, but for this purpose, an antistatic agent with a simpler molecular structure must Preferably, in this respect, stearyluge (β-hydroxybetaine)
Also, lower molecular weight N-acyl sarcosinates are more advantageous than alkylimidazoline type amphoteric activator metal salts. Second, the reason why N-acyl sarcosinate alone has poor performance is that the product has a relatively high melting point and remains crystalline at processing temperatures, which limits surface migration. However, coexistence with higher fatty acid polyhydric alcohol ester results in an amorphous composition, resulting in improved surface migration and a synergistic effect. Thirdly, since the antistatic agent having the above composition that has migrated to the surface is amorphous as described above, whitening cannot occur (whitening occurs due to crystallization). Fourth, although each of the antistatic components of the present invention alone can be expected to have some effect on slip properties and anti-blocking properties, in the two-component combination of the present invention, each component migrates to the surface at the same time. This will further enhance the effect and produce a synergistic effect. Fifth, the surface arrangement is convenient due to the molecular structure. Hereinafter, the details of the invention will be described in more detail with reference to Examples, but of course the examples are merely for illustration and are not intended to limit the idea of the invention. In addition, prior to giving examples, each test method used in the experiment will be listed. ●Anti-static effect Constant temperature with controllable temperature and relative humidity.
After leaving the measurement sample in a constant humidity chamber for 24 hours, a voltage of 500V was applied, and the surface specific resistance value was measured after 1 minute using a super megohmmeter (type VE40) manufactured by Kawaguchi Electric Seisakusho. ●Whitening After leaving the film or sheet at 40℃ for 30 days, the turbidity before and after washing with ethanol (ASTM-D
-1003) is taken as the bleaching index. That is, if the turbidity before ethanol washing is: [Evaluation] When the coefficient of friction is 0.8 to 1.0, no slip property is observed. When the coefficient of friction is 0.4 to 0.8, some slip property is observed. When the coefficient of friction is 0.2 to 0.4, slip property is considerably observed. When the coefficient of friction is 0.0 to 0.2, slip property is very good. ● Blocking resistance Two films are placed on top of each other in an area of 2 cm x 2 cm, a load of 1 kg (250 g/cm ² ) is applied thereto, and after being left at 40°C for 24 hours, the shear peeling force between the films is measured using an autograph. . [Evaluation] There is no practical problem if the shear peeling force is 1000 g or less, but preferably 500 g or less. Examples 1 to 12 and Comparative Examples 1 to 5 Low density polyethylene (Mitsubishi Yuka Co., Ltd. Yucalon K-
3200) were added with 0.2% by weight of each of the antistatic agent of the present invention and a comparative product, roll-kneaded at 170℃ for 5 minutes, and then press-molded at 150℃ under a pressure of 100Kg/cm ² to form a 1mm A thick press sheet was obtained. Table 1 shows the antistatic performance and surface properties of this sheet.

【table】

[Table] Examples 14-15 and Comparative Examples 6-8 High-density polyethylene
EA, EA150, MI5.0, density 0.955), the antistatic agent of the present invention and the comparative product were each added at 1.0% by weight.
After blending and melt-mixing, the mixture was extruded at 220° C. using an extruder with a T-die having a diameter of 50 mm to obtain a film with a thickness of 40 μm. Table 2 shows the antistatic properties of this film.

[Table] Examples 17-24 and Comparative Examples 9-11 Polypropylene (Mitsubishi Noblen FL6,
MI2.0) was mixed with 0.8% by weight of the antistatic agent according to the present invention and the control product, and extruded at 260°C using an extruder with a T-die with a diameter of 50mm using the T-die method to form a sheet with a thickness of 700μ. Obtained. This sheet
Next, it was stretched 5 times in the longitudinal direction with rolls adjusted to 150°C, and further using a pantograph type stretching machine,
A biaxially stretched film was obtained by stretching substantially 8 times in the transverse direction. The above stretched film was stretched for 20m/
Corona discharge treatment was performed under the conditions of 0.7A for 1 minute. Table 3 shows the antistatic properties and surface properties of the film thus obtained.

【table】

[Table] Example 25 Using the films obtained in Examples 18 and 23 and Comparative Examples 9, 10 and 11, bags of 5 cm x 10 cm were made. 3 g of desiccant (silica gel) and 10 g of dried bonito flakes were placed in this bag, sealed, and left at room temperature. 1
After a week, each bag was shaken by hand several times and the state of adhesion of the powdered flakes to the inner surface of the film was observed, and the results shown in Table 4 were obtained.

【table】

Claims (1)

[Claims] 1. A non-electrostatic polyolefin resin containing, as an essential component, a blend of N-acyl sarcosinate and higher fatty acid polyhydric alcohol ester in a weight ratio of 3:97 to 90:10 in a proportion of 0.03 to 3%. Composition.