JP2003080641A - Antistatic multi-layer film and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive antistatic multi-layer thermoplastic resin film which is excellent in antistatic effect and keeps the effect while preventing its change with the passage of time and to provide a method for producing the film. SOLUTION: In the antistatic multi-layer film, on both sides of a thermoplastic resin layer substantially free from an antistatic agent, antistatic layers 3-30 μm in thickness which are thinner than the thermoplastic resin layer and contain a polymeric antistatic agent having specific surface resistance of 10<9> Ω/(square) or below and a half-life shorter than one second are formed. The film is produced by a coextrusion method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance and inexpensive antistatic film of a thermoplastic resin which is excellent in antistatic effect, non-bleeding property (non-migrating property), aging and the like, and a method for producing the same.

[0002]

2. Description of the Related Art A conventional antistatic film made of a thermoplastic resin is prepared by kneading a thermoplastic resin with a surfactant, which is a low molecular weight antistatic agent such as alkylamine, glycerin stearate and alcohol, in an amount of about 0.25% by weight. The surface resistivity of the film is 10 ¹¹ to 1 by the bleeding of the antistatic agent on the surface of the film.
It was generally 0 ¹³ Ω / □. However, at the level of this antistatic effect, it can withstand the use of dust and powder to prevent it from adhering, but is sensitive to electrostatic damage in electric and electronic products such as printed wiring boards, ICs, transistors, capacitors, and resistors. In the case of various parts and products, there are problems such as antistatic effect and contamination due to migration of antistatic agent bleeding on the surface, which is insufficient for packaging electric and electronic parts.
It was mainly used for food packaging.

On the other hand, recently, a polymer type antistatic agent has been developed, and by adding 10 to 30% by weight to a thermoplastic resin, it becomes possible to produce an antistatic film having a surface specific resistance of 10 ⁹ to 10 ¹¹ Ω / □. , The polymer type antistatic agent has a non-bleeding property (non-migrating property), so the above problems have been solved, but the surface specific resistance is 10 ⁹ Ω / □.
There has been no technology for inexpensively producing a higher-performance antistatic film having the following half-life of less than 1 second.

[0004]

DISCLOSURE OF THE INVENTION As a result of various investigations by the inventors, in order to solve the above-mentioned problems of the prior art,
The present inventors have completed the present invention by finding that the performance of the antistatic film is largely determined by the antistatic performance of the surface portion, and that the antistatic performance inside the antistatic film has almost no effect.

That is, the present invention provides an inexpensive antistatic film of a thermoplastic resin having a surface resistivity of 10 ⁹ Ω / □ or less and a half-life of less than 1 second, which could not be produced by the prior art, and a method for producing the same. It is intended to provide.

[0006]

In order to achieve the above-mentioned object, according to the present invention, as an outer layer on both sides of a thermoplastic resin layer which does not substantially contain an antistatic agent, the thermoplastic resin layer is more preferable than the thermoplastic resin layer. A thin antistatic layer containing a polymer type antistatic agent having a surface resistivity of 10 ⁹ Ω / □ or less and a half-life of less than 1 second and having a thickness of 3 to 30 μm was provided 3.
An antistatic multilayer film comprising more than one layer is provided.

According to another aspect of the present invention, there is provided an antistatic film in which the concentration of the polymer type antistatic agent is 50 to 100% by weight. According to still another aspect of the present invention, the thermoplastic resin of the thermoplastic resin layer that does not substantially contain the antistatic agent is polyethylene, polypropylene, polyamide, polyethylene terephthalate (P
ET) and ethylene vinyl alcohol copolymer (EVO
H) or blends thereof are provided.

According to another aspect of the present invention, there is provided an antistatic multilayer film comprising at least three kinds of layers, each having a different concentration and / or kind of the polymer type antistatic agent contained in the antistatic layers on both sides. Provided. According to still another aspect of the present invention, there is provided an antistatic multilayer film having a functionalizing resin layer provided between the thermoplastic resin layer and at least one of the antistatic layers on both sides.
Further, according to still another aspect of the present invention, there is provided an antistatic film in which the total thickness of the antistatic multilayer film is 20 to 300 μm.

Further, according to the present invention, there is provided a method for producing an antistatic film, wherein the antistatic multilayer film is formed by an inflation type or T-die type coextrusion multilayer film forming method.

[0010]

The surface resistivity in the present invention is based on JIS-K-6911, and the half-life is also based on JIS-L1094. Measured temperature: 23
C, measured humidity: The value measured at 50% RH is shown.

In the present invention, an intermediate thermoplastic resin layer (hereinafter sometimes referred to as "B layer") and antistatic layers on both sides thereof (hereinafter sometimes referred to as "A layer" or "C layer"). .) (The thickness of the B layer / (the total thickness of the A layer and the C layer)) is 1.1 to 20, preferably 2 to 15, and the total thickness of the A layer and the C layer is 3. -30 μm, preferably 5-20 μm. When the thickness ratio is 1.0 or less, the cost reduction effect is smaller than that of the monolayer film, and the thickness ratio is 20.
When it becomes above, the antistatic effect of a multilayer film will fall.
If the total thickness of the antistatic layer is 3 μm or less, the antistatic stability is insufficient, and if the total thickness is 30 μm or more, the specifications are high and the cost is high.

Conventionally, a polymer type antistatic agent is used as a single layer film in which 10 to 30% by weight of a thermoplastic resin is kneaded, and the surface resistivity is 10 ¹⁰ Ω / □ even though the film cost is high. However, according to the present invention, the intermediate layer has an antistatic effect equivalent to that of a monolayer film even if an antistatic agent is not added, and has a surface specific resistance of 10 ⁹ Ω / □ or less and a half. It has become possible to inexpensively obtain a high-performance antistatic film having a period of less than 1 second.

In the present invention, these thermoplastic resins have only to be capable of extrusion molding and have resin properties such as strength suitable for the application, and the following ones are generally selected. That is, in addition to various polyethylenes and polyolefins such as ethylene-based copolymers and polypropylene, thermoplastic resins such as polyamide, polyethylene terephthalate (PET), ethylene vinyl alcohol copolymer (EVOH), and blends thereof can be used.

The polymer type antistatic agent used in the present invention is a mixture of a polyamide-based modified resin and a salt such as sodium perchlorate and monohydrate, and is an IRGAS manufactured by Ciba Specialty Chemicals Co., Ltd.
It is a mixture of TAT (registered trademark) P18 and Mitsui DuPont Polychemical Co., Ltd., which is an ionomer resin containing potassium as a metal ion and a polyhydric alcohol added thereto.
D100 (trade name) and the like are suitable. These are good antistatic agents with a surface resistivity of 10 ⁷ to 10 ⁹ Ω / □, but since they are very expensive, they have not been used as a single substance until now, and 20 wt% of the thermoplastic resin has been used. It was used as a single-layer film blended by about 100%.

These polymer type antistatic agents are
As long as the antistatic function is not impaired, the base material may be blended with a thermoplastic resin or other functional material in order to improve the adhesion to the base material. The concentration of the polymer type antistatic agent suitable from the viewpoint of antistatic function and economy is preferably 50 to 100% by weight.

B containing substantially no antistatic agent of the present invention
The multilayer film in which the antistatic layer A layer and the antistatic layer C are provided on both sides of the layer can be a 2 type 3 layer or a 3 type 3 layer multilayer film. In the former case, the A layer and the C layer have the same composition. The latter is commonly used in the A layer or C layer, and the latter contains various additives such as an antistatic agent, an antiblocking agent, a lubricant, an ultraviolet absorber, and a rust preventive, which impart other functionalities. It is used when the added function-imparting resin layer is formed. In addition,
When an adhesive resin layer is required between the intermediate layer (B layer) and the A and C layers, the number of layers is five.

In order to impart a gas barrier property to the antistatic multilayer film of the present invention, EVOH, polyamide, etc. are provided between the intermediate layer or the thermoplastic resin layer of the intermediate layer and at least one of the antistatic layers on both sides. A gas barrier resin layer can also be provided. Since the gas barrier resin layer generally does not have good adhesiveness with the thermoplastic resin layer, an adhesive resin layer is required in the middle, and in that case, the multilayer film of the present invention has at least 4 layers and 7 layers.

For the antistatic multilayer film of the present invention, either an inflation type or a T-die type coextrusion multilayer film forming method can be adopted. The molding temperature varies depending on the resin used, but is preferably 170 to 210 ° C. for the inflation method and 200 to 240 ° C. for the T-die method.

Specific examples and effects of the present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0020]

Example 1 A three-type five-layer inflation molding apparatus with a die diameter of 150 mm was used, and the outer layer (A layer) was a polymer type antistatic agent IRGASTAT P18 (copolymerized nylon base) manufactured by Ciba Specialty Chemicals Co., Ltd. , MFR2g in the middle thermoplastic resin layer (B layer)
/ 10 minutes, low-density polyethylene (LDPE) without lubricant with a density of 0.923 g / cm ³ , adhesive resin (C
Admer NF300 (trade name, MFR) which is a maleic anhydride modified polyethylene manufactured by Mitsui Chemicals, Inc.
1.3 g / min, density 0.94 g / cm ³ ) was used. The thickness of each layer is (A layer) 10 μm / (C layer) 5 μm / (B
Layer) 30 μm / (C layer) 5 μm / (A layer) 10 μm with a total film thickness of 60 μm, and molding was performed at a resin temperature of 200 ° C. In this case, the layer ratio of the outer layer to the intermediate layer is 1: 4: 1.

The obtained three-kind five-layer film was placed in a thermostatic chamber (23
Surface resistivity after conditioning for 7 days at ℃ -50% RH, 2 × 10 ⁸ Ω / □, half-life (measured with static Honest meter H0110 manufactured by Shishido Electrostatic)
The withstand voltage was 0.01 KV in less than 0.2 seconds.

[0022]

[Example 2] A three-layer, three-layer inflation molding apparatus with a die diameter of 150 mm was used, and the intermediate layer (B layer) was MFR.
Low-density polyethylene (LDPE) with a lubricant of 1.5 g / 10 min and a density of 0.924 g / cm ³ , and the outer layer (A layer) on both sides is a polymer type permanent charge made by Ciba Specialty Chemicals Co., Ltd. IRGA which is an inhibitor
30 parts of the LDPE in 65 parts of STAT P18 (copolymerized nylon base) and Lexpearl (registered trademark) ET18 of Japan Polyolefin Co., Ltd. as an eye improver
5 parts of 2 (copolymer of ethylene, acrylic ester and acid anhydride, MFR 8 g / 10 min, density 0.94) was added,
Layer ratio of outer layer (A layer) to intermediate layer (B layer) 1: 4: 1 (10
(μm / 40 μm / 10 μm) and a total film thickness of 60 μm were molded at a resin temperature of 200 ° C.

The obtained two-kind three-layer film had a surface resistivity of 9 × 10 ⁸ Ω / □ after 7 days in a temperature-controlled room, and a half-life (measured by a static Honest meter manufactured by Shishido Electrostatics) 0.3.
The withstand voltage was 0.03 KV. Although the antistatic agent is a polyamide base, 30 parts of low density polyethylene (LDPE) and 5 parts of ET182 are added to the A layer, so that the LDPE (B layer) of the intermediate layer and the A layers on both sides are Adhesion was not a problem in practical use.

[0024]

[Example 3] A T-die molding machine of three types and five layers having a die width of 1.5 m was used, and IRGASTAT P18 from Ciba Specialty Chemicals Co., Ltd. as an outer layer (A layer) and an intermediate layer (B layer). MFR 3.5g / 10min, density 0.930
Linear low-density polyethylene (LLD) with a single-site type catalyst of Adtex ER507L-5 (trade name, MF of Japan Polyolefin Co., Ltd.)
R2.8 g / 10 min, density 0.92) is used, and the thickness of each layer is (A layer) 5 μm / (C layer) 5 μm / (B layer) 50
70 μm in total of μm / (C layer) 5 μm / (A layer) 5 μm
And was molded at a resin temperature of 220 ° C. In this case, the layer ratio of the outer layer (A layer) to the intermediate layer (B layer + C layer) is 1: 12: 1.
Is. The surface resistivity of the obtained three-kind five-layer film after 7 days in a constant temperature room was 5 × 10 ⁸ Ω / □, a half-life of 0.3 seconds, and a withstand voltage of 0.03 KV.

[0025]

[Example 4] A three-layer three-layer inflation molding apparatus having a die diameter of 150 mm was used, and the intermediate layer (B layer) was MFR.
Low-density polyethylene (LDPE) with a lubricant of 2.0 g / 10 minutes and a density of 921 g / cm ³ , and the outer layer (A layer) on both sides is a polyhydric alcohol added to a potassium type ionomer manufactured by Mitsui DuPont Polychemical Co., Ltd. Polymer type antistatic agent SD100 was added to the above LDP in 60 parts.
The one to which 40 parts of E was added was used. Layer ratio of outer layer (A layer) to intermediate layer (B layer) 1: 4: 1 (10 μm / 40 μm /
A film having a thickness of 10 μm and a thickness of 60 μm was formed at a resin temperature of 180 ° C. The surface resistivity of the obtained two-kind three-layer film after 14 days in a temperature-controlled room was 5 × 10 ⁹ Ω / □, a half-life of less than 0.2 seconds, and a withstand voltage of less than 0.01 KV. The antistatic agent had a large humidity dependency and had a surface specific resistance of 9 × 10 ⁷ Ω / □ at 70% RH.

[0026]

[Comparative Example 1] A polymer type antistatic agent IRG was used by using an inflation molding apparatus with a die diameter of 150 mm.
A 60 μm single layer film of ASTAT P18 was molded at a resin temperature of 210 ° C. The surface resistivity of the obtained monolayer film was 3 × 10 ⁸ Ω / □, the half-life was less than 0.2 seconds, and the withstand voltage was 0.01 KV, which was the same as in Example 1. However, the material cost was 2.5 times as high as that of Example 1 and was very impractical.

[0027]

Comparative Example 2 The same as Comparative Example 1 except that the film thickness was 70 μm. The antistatic effect is slightly better than that of Example 3, but the material cost is 5 times higher than that of Example 3 and is completely impractical.

[0028]

The present invention provides a high-performance and inexpensive antistatic multilayer film of a thermoplastic resin excellent in antistatic effect, non-bleeding property (non-migrating property), aging and the like, and a method for producing the same. The antistatic multilayer film according to the invention is suitable not only for packaging various electric / electronic products such as printed wiring boards, ICs, transistors, capacitors, resistors, etc., which are subject to electrostatic damage, but can also be used for food packaging applications. Is.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takumi Maruyama             2-27-9 Minamiikebukuro, Toshima-ku, Tokyo Tamapoli             Within the corporation F-term (reference) 4F100 AK01A AK01B AK01C AK01H                       AK04B AK06A AK06C AK07B                       AK42B AK46B AK69B AR00D                       BA03 BA04 BA06 BA07 BA10A                       BA10C BA10D CA22A CA22C                       EH202 GB15 GB41 JB16A                       JB16B JB16C JD08 JG03                       JG04A JG04C JG04H YY00                       YY00A YY00C

Claims (7)

[Claims] 1. An outer layer on both sides of a thermoplastic resin layer that does not substantially contain an antistatic agent, is thinner than the thermoplastic resin layer, has a surface resistivity of 10 ⁹ Ω / □ or less, and has a half-life of 1 or less. An antistatic multilayer film comprising three or more layers, which is provided with an antistatic layer having a thickness of 3 to 30 μm, which contains a polymer type antistatic agent for less than a second. 2. The antistatic multilayer film according to claim 1, wherein the concentration of the polymer type antistatic agent in the antistatic layer is 50 to 100% by weight. 3. A thermoplastic resin layer containing substantially no antistatic agent, wherein the thermoplastic resin is polyethylene, polypropylene, polyamide, polyethylene terephthalate (PET) or ethylene vinyl alcohol copolymer (E).
VOH) or their blends, The antistatic multilayer film according to claim 1 or 2. 4. The concentration and / or type of the polymer type antistatic agent contained in the antistatic layers on both sides are different from each other and each layer is composed of at least three types of layers. The antistatic multilayer film according to. 5. The function-imparting resin layer is provided between the intermediate layer or the thermoplastic resin layer and at least one of the antistatic layers on both sides of the thermoplastic resin layer. Antistatic multilayer film. 6. The total thickness of the antistatic multilayer film is 20 to 300 μm.
The antistatic multilayer film according to any one of 1. 7. A method for producing an antistatic multilayer film, comprising molding the antistatic multilayer film according to claim 1 by an inflation type or T-die type coextrusion multilayer film forming method. .