JPS62132948A - Electrically conductive polypropylene film - Google Patents

Abstract

PURPOSE:A film, obtained by blending specific polypropylene with carbon black and having god electric conductivity and heat resistance and improved thickness accuracy without crease. CONSTITUTION:A film obtained by blending (A) 100pts.wt. polypropylene containing at least 3wt% propylene-alpha-olefin random copolymer with (B) 5-50pts. wt. carbon back. A propylene-alpha-olefin random copolymer with 0.1-6wt% is used as the propylene-alpha-olefin random copolymer and polypropylene of 100wt% above-mentioned copolymer is preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a conductive polypropylene film that has good conductivity and heat resistance, and has excellent thickness accuracy.

[Conventional technology]

Conventionally, as a conductive plastic film, a film made by blending carbon black with polyethylene is known.

However, in recent years, conductive plastic films have come to be used in various fields, and there is a demand for films with better heat resistance.

However, the conductive plastic film based on polyethylene described above lacks heat resistance, and there is a need for improvement.

By the way, if you just want to improve the heat resistance of the film, there is a way to use polypropylene, but in reality,
When carbon black is added, surging and uneven cooling are likely to occur during film forming, resulting in poor thickness accuracy and continuous wrinkles.
The reality is that films using black cannot be put to practical use as conductive plastic films.

[Problem that the invention seeks to solve]

The present invention was made in order to solve the above-mentioned problems in film formability, and its purpose is to provide a conductive film that is wrinkle-free, has good thickness accuracy, and has excellent conductivity and heat resistance. The purpose of the present invention is to provide a polypropylene film with high properties.

[Means for solving problems]

The present inventors have diligently studied the above-mentioned problems, and found that if a specific polypropylene is used and the amount of carbon black is limited to a specific range, a conductive material with excellent wrinkles, thickness accuracy, conductivity, and heat resistance can be achieved. The present inventors have discovered that a polypropylene film with a polypropylene content can be obtained, and have completed the present invention.

That is, the present invention provides at least 3% by weight of propylene-
This is a conductive polypropylene film characterized by comprising 100 parts by weight of polypropylene, which is an α-olefin random copolymer, and 1 part of carbon plaque from 5 to 5 parts.

The polypropylene used in the present invention is 3% by weight or more,
Preferably 1% or more per cap, more preferably approximately 100%
% of propylene-α-olefin random copolymer. i.e. other polypropylene,
For example, even when a propylene homopolymer or a propylene-α-olefin block copolymer is used, at least 3% by weight is a random copolymer of propylene and an α-olefin such as ethylene, butene, pentene, or hexene. In addition, the content of α-olefin in the propylene-α-olefin random copolymer is 0.1
The amount is preferably about 6% by weight.

If the propylene-α-olefin random copolymer is less than 3% by weight, the resulting film will have poor thickness accuracy;
On the other hand, if the amount is 3% by weight or more, a good film without wrinkles or poor thickness distribution due to uneven cooling can be obtained.

The polypropylene used in the present invention has a melt flow index (g/10 min, hereinafter abbreviated as Ml) of 0.5 to 2.
A value of about 0 is preferable, and a value of 2 to 10 is particularly preferable from the point of view of film formability.

The polypropylene used in the present invention may contain low-density polyethylene, medium-high density polyethylene, ethylene-propylene copolymer rubber, etc., as necessary, within a range that does not impair physical properties.

Carbon black that can be used in the present invention includes:
Any material that can be blended with a resin such as channel black, furnace black, thermal black, or acetylene blank to impart conductivity may be used, such as Ketjen Blank (trademark), Conducte Plus 5c1950 (
There are commercially available products such as Vulcan XC72 (Trademark) and Vulcan

The amount of carbon black to be blended is 5 to 50 parts by weight, preferably 8 to 2 parts by weight, per 100 parts by weight of polypropylene.
It is 5 parts by weight. Within this range, processability is good, and the resulting film has a good balance between electrical conductivity and mechanical strength. In addition, if it is less than 5 parts by weight, the volume resistivity of the film becomes too large and the conductivity becomes insufficient.

In addition, if the amount exceeds 50 parts by weight, processability will decrease,
Mechanical strength also deteriorates, making it impossible to obtain a good film.

The method for producing the conductive polypropylene film of the present invention is not particularly limited, but for example, polypropylene, carbon
Black, various polypropylene stabilizers and additives are mixed using a Henschel mixer, etc., and pelletized using an extruder.
Next, a known method using a T-die film molding machine or a blown film molding machine can be used. From the viewpoint of wall thickness accuracy, the T-die method is preferable.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 100 parts by weight of propylene-ethylene random copolymer (M I = 8) with an ethylene content of 5% by weight, 25 parts by weight of acetylene black, 2.6-di-t-butyl-
After mixing 0.1 part by weight of 4-methylphenol and 0.1 part by weight of calcium stearate using a Henschel mixer, the mixture was made into pellets using an extruder having a diameter of 401 mm at 230°C.

Next, this pellet was extruded from a T-die with a diameter of 401 at 240° C., and a film having a medium diameter of 300 mm and a set thickness of 30 μm was obtained using a combination of an air knife and a chill roll.

The performance of the obtained film was evaluated regarding the following items. The results are shown in Table-1.

(11 Formability: The state of the film was visually observed during film molding, and the presence or absence of surging and thickness distribution were determined.

O: No surging, thickness distribution good ×: Surging present, thickness distribution poor Judgment was made based on the average value (X) and range R (maximum value - minimum value).

(3) Conductive two-volume specific resistance was measured according to JIS K-6723.

(4) Heat resistance: Toyo f# was marked with a 10cm long dermatograph on the center of a film measuring #115cIm x width 15c11 using a dermatograph made by Mitsubishi Pencil ■ and set at 140℃.
The slate was temporarily placed in a gear aging tester manufactured by Kishi Seisakusho, and left in a horizontal position for 30 minutes. Thereafter, it was taken out, cooled to room temperature, and changes in size and shape were observed.

O: No change in size and shape ×: Change in size and shape Comparative Example 1 A film was obtained in the same manner as in Example 1 except that a propylene homopolymer was used as the polypropylene. The evaluation results are shown in Table-1.

Example 2 Ethylene-propylene random copolymer with M T = 1.5 as polypropylene (ethylene content 5%)
) was used, but a film was obtained in the same manner as in Example 1. The evaluation results are shown in Table-1.

Comparative Example 2 A film was obtained in the same manner as in Example 2, except that a propylene homopolymer was used as the polypropylene. The evaluation results are shown in Table-1.

Example 3 A film was obtained in the same manner as in Example 1, except that a mixture of 96 parts by weight of a propylene homopolymer and 4 parts by weight of an ethylene-propylene random copolymer (ethylene content: 5%) was used as the polypropylene. The evaluation results are shown in Table-1.

Comparative Example 3.4 A film was obtained in the same manner as in Example 1, except that the amount of carbon black used was changed to the amount shown in Table 1. The evaluation results are shown in Table-1.

Example 4 Instead of acetylene black, “Ketjen black” (
A film was obtained in the same manner as in Example 1, except that 10 parts by weight of the aliquot was used. The evaluation results are shown in Table-1.

Example 5 Example 1 except that the set thickness of the film was set to 20#-
A film was obtained in the same manner as above. The evaluation results are shown in Table-1.

Comparative Example 5 A film was obtained in the same manner as in Example 1, except that low density polyethylene Luxuron F41' (trademark, MI=5) was used instead of polypropylene. The evaluation results are shown in Table-1.

〔Effect of the invention〕

Since the conductive polypropylene film of the present invention has unprecedented thickness accuracy and heat resistance, its range of use is extremely wide and it will greatly contribute to industry.

Claims (1)

[Scope of Claims] 1. A conductive polypropylene film comprising 100 parts by weight of polypropylene of which at least 3% by weight is a propylene-α-olefin random copolymer and 5 to 50 parts by weight of carbon black. α of propylene-α-olefin random copolymer
- The conductive polypropylene film according to claim 1, having an olefin content of 0.1 to 6% by weight.