JPS61146893A - String like article - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a string-like material made of stretched synthetic resin films, and more specifically, a string-like material that is flame retardant and has a large apparent specific volume.
In particular, the present invention relates to a string-like material suitable for being filled as an inclusion between multi-core twisted wires.

[Prior Art] In general, a covered wire made by twisting together a plurality of coated conductors is finished in a cylindrical shape by covering its outer periphery with a protective material that reinforces it. It is necessary to fill the space between the cylindrical exterior material (sheath material) with some kind of inclusion. Such inclusions include
It is desirable to use a material that is economically inexpensive and can fill a large volume with a small amount.Also, since the cut surface does not unravel and is filled uniformly, it fits well into the gaps of the covered wire (filling degree) and is suitable for use. It has flexibility, does not shrink or melt during heat processing when applying the exterior material, and has sufficient strength so as not to break when drawn out from the cheese as an intervening string.
It is required to have low water absorption.

[Problems to be Solved by the Invention] Conventionally, string-like materials such as jute string, paper string, stretched synthetic resin film, split yarn, and split fiber have been used as inclusions in covered electric wires, but each of the above-mentioned Recently, for example, inclusions in coated wires with large volumes have a large apparent specific volume that can fill a large volume with a small amount, and are strongly flame retardant. desired. Although the above-mentioned stretched film string has a considerable apparent specific volume, it has the disadvantage that it is difficult to fit into the gap between the coated conductors, and if forced into it, the apparent specific volume becomes small.

Therefore, an object of the present invention is to provide a desired string-like material using a stretched synthetic resin film that is flame retardant, has a large apparent specific volume, and has good compatibility (filling degree) with covered electric wires.

[Means for Solving the Problem] In view of the above, the present inventors have conducted intensive research by blending various flame retardants with polyolefin, and as a result, stretched a resin composition consisting of polyolefin, red phosphorus, and a water-containing inorganic filler. It has been discovered that by forming a film, a flexible string-like material that has flame retardancy, is condensed, has a significantly large apparent specific volume, and has extremely good conformability (filling degree) can be obtained,
This has led to the provision of the present invention. That is, the present invention contains 45 to 80% by weight of polyolefin and 5 to 13% by weight of red phosphorus.
It is a string-like product made by bundling stretched films of a resin composition containing 15 to 40% by weight of a water-containing inorganic filler.

It is known that the resin composition of the present invention, which includes polyolefin, red phosphorus, and a water-containing inorganic filler, has flame retardancy (Japanese Patent Publication No. 16144/1983).

However, Japanese Patent Publication No. 57-16144 discloses that a string-like material made by bundling stretched films of such flame-retardant resin compositions has an extremely large apparent specific volume and an extremely good conformability (filling degree). There is no suggestion whatsoever about the effect of exhibiting flexibility. That is, as a result of studying a large number of flame retardants and flame retardant compositions, the present invention has found that a desired string-like material can be selectively obtained from the above-mentioned compositions.

The polyolefin used in the present invention is not particularly limited, but generally polyethylene, polypropylene, ethylene-
It is preferable that the propylene block copolymer obtained from the string has a high elastic recovery rate against external pressure, maintains a large apparent specific volume, and conforms to the shape formed by external pressure. In addition, commercially available powdered red phosphorus is used as it is, and it is generally preferable to have a particle size of 10μ or less.
The water-containing inorganic filler may be any material having bound water in its molecule or a hydroxyl group capable of thermally decomposing to generate water, but magnesium hydroxide and basic magnesium carbonate are particularly preferably used.

Furthermore, other inorganic fillers such as calcium carbonate and talc/clay can be used in combination, if necessary. In addition, it is recommended to eliminate free water contained in the above-mentioned polyolefin, red phosphorus, water-containing inorganic filler, etc. in advance as much as possible.
This is desirable in order to obtain a desired good stretched film from the polyolefin composition.

Blending the polyolefin, red phosphorus, and water-containing inorganic filler in the polyolefin composition of the present invention in specific proportions improves not only the flame retardancy of the obtained string but also a large apparent specific volume and good conformability. Stability (filling degree) is extremely important, especially in order to obtain a string-like material useful as an inclusion in a covered wire. This is because even polyolefin compositions that do not satisfy any one of the blending ratios specified in the present invention exhibit flame retardancy, but the purpose of obtaining a desired string-like product from the stretched film of the present invention cannot be achieved. This is because it is not possible.

In the present invention, the method for obtaining a stretched film from a polyolefin composition is not particularly limited, and any known means may be employed. The polyolefin composition can be prepared by kneading polyolefin, red phosphorus, and water-containing inorganic filler within a specified mixing ratio, or by kneading polyolefin, red phosphorus, and water-containing inorganic filler in a ratio higher than the specified ratio in advance. By the method using a material (masterbatch),
A predetermined polyolefin composition is obtained.Then, the polyolefin composition is made into pellets and subjected to film formation.

The film is produced by a conventional calendering method, T-die method, or inflation method, and is uniaxially or biaxially stretched at a temperature below the melting point of the film to obtain a stretched film having a predetermined width and a thickness of generally 5 to 80 μm. . The stretching ratio of the film varies depending on the blending ratio of the polyolefin composition, the thickness of the film, etc., and cannot be determined unconditionally, but it is generally 3 to 3.
By making the film stretched 6 times, the apparent specific volume becomes 3
cm/g or higher, it is possible to obtain a string-like material that has sufficient strength and has good adaptability.

Furthermore, in the present invention, by obtaining a stretched film in which a large number of protrusions are formed particularly in the longitudinal direction from a predetermined polyolefin composition, the apparent specific volume of the desired string-like product can be further increased. I can do it. The ridges formed on such a stretched film generally have a cross-sectional shape with a height of 2 to 8 times the thickness of the film, a maximum width of 5 to 50 times the thickness of the film, and an interval of 2 to 20 cm. ■ It is desirable to provide a protruding gap of 2 to 3 m.
The uniaxially stretched film provided at m+ has crepe-like wrinkles (emboss) formed in the film due to the difference in heat shrinkage between the flat part and the protruding part of the film, so it is easy to bundle and has a good string. You can get something like this. The method for producing a stretched film having a large number of protrusions as described above is not particularly limited, but in general, the mouth of the T-die that is to be formed into a film is preliminarily spaced at predetermined intervals in the flow direction of the resin, and each has a predetermined width. This can be obtained by setting depth increments.

Next, in the present invention, there are no particular restrictions on the method for converging stretched films into a string shape. It is simple and effective to bundle one or more sheets into a wired string by passing them through a hole of a desired diameter.Also, 1. By lightly twisting the strings when gathering them into a string-like object, The shaped material is effective because it can be placed extremely uniformly as an inclusion between the covered wires.Furthermore, by fusing the focused surfaces of the stretched film, the whole can be easily finished into a cylindrical shape, and the cut surface A string-like material with a smooth surface that does not unravel can be obtained, and is particularly easy to fit between coated wires, and has excellent workability and finishability.

[Effects of the Invention] As explained below, the present invention has excellent flame retardancy and an apparent specific volume of 3 cm/g or more, preferably 5 cm+
/g or more, a composition having flexibility and conformability (filling degree) and sufficient strength can be obtained. Therefore, the string-like material of the present invention is extremely useful especially as an inclusion between coated wires, but
The present invention is not limited to this, and can be used in other fields such as string-like materials for packing.

[Example] Examples will be shown below, but the present invention is not limited thereto.

Example 1 A polypropylene composition having a melt index of 6 (Toku 111 Sodasha Co., Ltd.) and containing magnesium hydroxide and red phosphorus in the proportions shown in Table 1 was pelletized and formed into a film.The film was formed by inflation molding. After obtaining a film having a thickness of 30μ, a width of 270wn, and a protrusion of 160μ in height with a spacing of 4++ug in the longitudinal direction, the film was stretched 5 times at a temperature of 130°C. The stretched film has a diameter of 511IIl.
It was concentrated into a string-like material through a hole in the hole. The properties of the obtained string-like material are also listed in Table 1.

Table 1 Note: The above oxygen index is based on ASTM D-28631.
Measured according to the same method.

Example 2 A string-like product was obtained in the same manner as in Example 1 except that commercially available polyethylene having a melt index of 6 was used in place of the polypropylene in Example 1 at the blending ratio shown in Table 2. The results are shown in Table 2.

Table 2

Claims (10)

[Claims] (1) Polyolefin 45-80% by weight, red phosphorus 5-1
A string-like product made by bundling stretched films of a resin composition containing 3% by weight and 15 to 40% by weight of a water-containing inorganic filler. (2) The string-like material according to claim 1, having an apparent specific volume of 3 cm/g or more. (3) The string-like material according to claim 1, wherein the polyolefin is polypropylene or an ethylene-propylene copolymer. (4) The string-like material according to claim 1, wherein the water-containing inorganic filler is magnesium hydroxide or basic magnesium carbonate. (5) The string-like material according to claim 1, having a stretching ratio of 3 to 6. (6) The string-like material according to claim 1, wherein the film has a thickness of 5 to 80 μm. (7) A string-like object according to the claims, which is a stretched film having a large number of protrusions in the longitudinal direction. (8) A string-like article according to claim 1, which is made of twisted stretched film. (9) The string-like object according to claim 1, wherein the surface of the bundle is fused. (10) The string-like object according to claim 1, which is an inclusion of a covered electric wire.