JPH0774280B2 - Polypropylene uniaxially stretched molded product - Google Patents

Description

TECHNICAL FIELD The present invention relates to a uniaxially stretched polypropylene propylene molded product, and more particularly to a novel polypropylene uniaxially stretched uniaxially stretched molded product such as a flat yarn or band having improved strength and longitudinal cracking property. It relates to stretch-molded products.

[Conventional technology]

Uniaxially stretched molded products such as flat yarns, bands, tapes and monofilaments made of polypropylene have excellent mechanical strength and are therefore widely used as industrial materials such as various bags, cross sheets, ropes, nets and binding materials.
As a method of increasing the strength of such a uniaxially stretched molded article, a method of using polypropylene having a higher molecular weight and stretching at a higher ratio has been attempted. That is, in the uniaxially stretched molded product, molecular orientation occurs in the stretching direction as the stretching ratio increases, and the strength in the stretching direction is improved. However, at the same time, the strength in the axial direction gradually decreases, and as a result, cracks are formed in the stretching direction, which easily causes a vertical crack phenomenon, which is a major drawback. A uniaxially stretched product that is easy to be longitudinally cracked even if it has such strength has vertical cracks, fluffing, etc. in each process such as warping, twisting, uneven weaving, etc. until it is commercialized and in the binding process using an automatic binding machine. As a result, the strength of the uniaxially stretched material is severely deteriorated, and the improvement in the strength of the uniaxially stretched material cannot sufficiently contribute to the improvement of the strength of the final product such as bags, cloth sheets, ropes, nets and binding materials.

For example, if a polypropylene flat yarn with a relatively high strength but a low elongation of 6 g / d, a fineness of 1500 denier and a strength of 6 g / d and an elongation of about 21% is used for the weft yarn of a Sulzer fiber machine to finish into a cross sheet, The weft strength of the sheet
It is said that it will be reduced to about 40 to 50%, and in that case, the practical strength of polypropylene flat yarn is only 3 to 3.6 g / d.

Therefore, in order to increase the value of the uniaxially stretched product in practical use, it is essential to improve the strength of the stretched product and to make it resistant to longitudinal cracking. As its improvement, higher molecular weight polypropylene is used, or a resin composition obtained by adding calcium carbonate, rubber, ethylene propylene copolymer, etc. to the higher molecular weight polypropylene is used, or those resin compositions are used. There has been proposed a method for making a high-strength drawing. Here, in order to facilitate extrusion moldability and stretchability by using a high-molecular-weight polypropylene and improve the strength and longitudinal cracking property of the obtained uniaxially stretched product, first of all, it is necessary to have uniform physical properties. It is important to obtain a stretched raw fabric and then to improve the stretchability. However, if the polypropylene to be used is simply made to have a high molecular weight, the flow resistance at the time of melt extrusion becomes large and the extrusion moldability deteriorates. To compensate for this, it is necessary to perform extrusion molding at a higher temperature.However, due to the high temperature extrusion, the heat deterioration of polypropylene proceeds, resulting in unstretched raw material or discoloration or roughened surface or uneven crystallinity. As a result, the stretchability becomes difficult, and as a result, the strength of the stretched product and the improvement of longitudinal cracks cannot be expected. Further, the method of adding calcium carbonate, rubber, ethylene propylene copolymer and the like is not sufficient for improving the vertical cracking property, and there is a problem that addition of these causes a decrease in strength.

[Problems to be Solved by the Invention]

In view of the above-mentioned drawbacks of the polypropylene uniaxially stretched molded article, the present invention improves the strength and simultaneously improves the longitudinal cracking property, and suppresses the deterioration of the strength in the secondary step up to the product or in the practical use of the product. An object of the present invention is to provide a polypropylene uniaxially stretched molded article having a high practical value.

[Means for Solving the Problems]

As a result of intensive studies for solving the above problems, the present inventors have found that it is necessary to balance both strength and elongation at a high value as required physical properties of a polypropylene uniaxially stretched molded product. It is considered essential to improve extrusion fluidity of polypropylene having a molecular weight (B) Specific antioxidant (C)
The present invention has been completed, knowing that the initial purpose can be achieved by uniaxially stretching using a resin composition containing a specific lubricant (D) and a specific fluidity aid.

That is, in the present invention, (A) 100 parts by weight of crystalline polypropylene, (B) hindered phenol compound 0.10 to 1.
Melt flow rate of 0.1 to 1.0 g / 10 min of 0 part by weight, (C) fatty acid amide or a mixture of fatty acid amide and metal soap 0.1 to 2.0 parts by weight, and (D) silicone oil 0.01 to 0.50 parts by weight After extrusion molding the resin composition,
Another object of the present invention is to provide a polypropylene uniaxially stretched composition characterized by being uniaxially stretched.

The crystalline polypropylene (A) used in the present invention is a normal polypropylene obtained by polymerizing propylene while adjusting the molecular weight with hydrogen using a Ziegler-Natta catalyst or the like, and is mainly a propylene homopolymer or propylene. As an ingredient, this and other α-such as ethylene and butene-1
Although it may be any of copolymers with olefins, homopolymers of propylene or copolymers with a very small amount of comonomer are more preferable.

Examples of the (B) hindered phenol compound in the present invention include (a) 2,6-di-t-cresol,
(B) Tetrakis [methylene (3,5-di-t-butylhydroxyphenyl) bropionate] methane, (c) 1,
3,5 trimethyl 2,4,6 tris (3,5-di-t-butylhydroxybenzyl) benzene, (d) 1,3,5-tris (3,5
Examples thereof include, but are not limited to, di-butyl-4-hydroxybenzyl) isocyanurate.

As the aliphatic amide in the fatty acid amide (c) or the mixture of fatty acid amide and metal soap used in the present invention, a fatty acid amide having 12 to 24 carbon atoms is preferably used. Specific examples thereof include palmitic acid amide, stearic acid amide, oleic acid amide, linoleic acid amide, and erucic acid amide, and these can be used alone or in combination of two or more. Examples of the metallic soap include higher fatty acids described below and alkali metals such as sodium, potassium or lithium,
Alternatively, a salt with an alkaline earth metal such as magnesium can be used. Examples of the higher fatty acid include stearic acid and 12-hydroxystearic acid. Specific examples of such metal soaps include sodium stearate, sodium 12-hydroxystearate, calcium stearate, calcium 12-hydroxystearate, magnesium theearate, and zinc stearate.

The (D) silicone oil used in the present invention may be selected from methyl silicone oil, methylphenyl silicone oil, organic modified silicone oil, etc., but it improves the melt fluidity of the polypropylene resin during extrusion under high temperature and high pressure. In order to exert the effect of lowering the melt extrusion temperature more, it is preferable that it has excellent lubricity and heat resistance, specifically, a silicone oil having a viscosity at 25 ° C of 200 to 1000 centistokes (CSt). Is more preferable.

The amount of each of the above additives added to the resin composition used in the present invention is (B) hindered phenolic compound 0.1 to 1 part by weight, preferably 0.2 to 0.5 part by weight, based on 100 parts by weight of polypropylene (A). C) 0.1 to 2 parts by weight, preferably 0.5 to 1.5 parts by weight of fatty acid amide or a mixture of fatty acid amide and metallic stone (D) silicone oil 0.01 to
0.50 parts by weight It is preferably in the range of 0.03 to 0.20 parts by weight.
If the amount is insufficient with respect to the above amount, the object of the present invention cannot be sufficiently achieved. On the other hand, if the amount exceeds the above-mentioned amount, the effect of improving extrusion fluidity is saturated, and on the contrary, the price of the resin composition becomes expensive, which is not preferable.

The melt flow rate of the resin composition used in the present invention (23
0 ° C, 2.16 kgf or less MFR) is required to be 0.1 to 1.0 g / 10 min. If the MFR exceeds 1.0 g / 10 min, a uniform unstretched raw fabric can be easily obtained and stretching is easy, but the obtained stretched product cannot be given sufficient strength. Further, if the MFR is less than 0.1, the melt extrudability is poor, heat generation and melt fracture are likely to occur, and a uniform unstretched raw fabric without deterioration cannot be obtained, so it is expected to improve the strength of the stretched product and improve the vertical cracking property. Can not.

The resin composition used in the present invention is obtained by blending (A) the crystalline polypropylene with the above-mentioned respective additives (B), (C) and (D) in the above-mentioned proportions and mixing them. The method of mixing is not particularly limited, and an ordinary kneading method can be applied. For example, a method in which polypropylene powder or pellets are mixed with each additive, premixed at room temperature, and then melt-kneaded with an extruder or the like is suitable.

The resin composition used in the present invention includes, in addition to the above-mentioned additives, an ultraviolet absorber, a nucleating agent, a pigment, etc. Matting agents and the like can be added within a range that does not impair the objects and effects of the present invention.

Next, a method for producing the polypropylene uniaxially stretched molded product of the present invention will be described. The polypropylene uniaxially stretched molded product of the present invention is manufactured using the resin composition obtained by the above-mentioned method as a raw material, but the manufacturing method is not particularly limited, and it can be carried out by known publicly-used devices and methods. For example, the resin composition of the present invention is melt-extruded as a raw material to extrude an unstretched raw material such as a film, a sheet and a monofilament. Then, the unstretched raw fabric is stretched uniaxially to produce flat yarns, tapes, monofilaments, or bands, whereby the polypropylene uniaxially stretched molded product of the present invention is obtained.

Extrusion molding of unstretched raw fabric is carried out by a commonly used molding apparatus and molding method for films, sheets, monofilaments, etc., such as inflation molding method using a circular slit die, T die molding method using a T die, and yarn-proof molding using a circular nozzle die. The resin composition of the present invention is used at a resin temperature of 18
Extrude at a temperature of 0 to 300 ° C.

In the case of inflation molding, the resin composition is 180-300 ℃
After extrusion, the inflation film was formed with a blow-up ratio of 1.0 to 1.5 by air cooling or water cooling, and in the case of T die forming, the resin composition was extruded at 180 to 300 ° C and then adjusted to 20 to 80 ° C. A film is formed by water cooling or roll cooling, and in the case of yarn prevention using a circular nozzle die, the resin composition is added to 180 to 3
It is desirable to form filaments by extruding at 00 ° C followed by water cooling at 5-80 ° C.

Films, sheets obtained by extrusion molding as described above,
An unstretched raw material such as a monofilament is slit between two or more pairs of nip rolls having different rotation speeds while being heated by a known method such as a heating roll method or a heated air bath method without slitting into an appropriate width. It is possible to carry out multi-stage drawing of one step or two or more steps in the length direction. The stretching conditions may be ordinary stretching temperature and stretching ratio for stretching the polypropylene resin. Specifically, the stretching temperature may be a heating medium temperature of 70 to 230 ° C. and a stretching ratio of 4 to 15 times, preferably a stretching temperature of 90 to 200 ° C. and a stretching ratio of 5 to 10 times.

Next, the stretched polypropylene uniaxially stretched molded product of the present invention is preferably subjected to a relaxation heat treatment (annealing) by a known device and method in order to remove strain due to stretching and prevent temporal shrinkage.

[Examples and Comparative Examples]

The present invention will be specifically described with reference to Examples and Comparative Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

The evaluation methods carried out in Examples and Comparative Examples were as follows.

(1) MFR: ASTM-D1238 Condition L (2) ΔMFR: Difference between the MFR of the resin composition and the MFR of the unstretched raw material obtained by extrusion molding the resin composition. The smaller the value, the polypropylene resin composition. It shows that it has good heat resistance, oxidation stability and fluidity during melt extrusion.

(3) Tensile test: JIS Z1527-1976 (measurement environment:
・ Temperature 23 ± 1 ℃ ・ Humidity 50 ± 3%) (4) Longitudinal cracking property: As longitudinal cracking property, weaving a uniaxially stretched material with a Sulzer fiber machine, then weaving this, and conducting a tensile test of the unwoven yarn, The vertical cracking property was obtained by obtaining the residual strength and the strength retention rate.

Examples 1 to 4 (A) 0.03 part by weight of tetrakis [methylene (3,5-di-butylhydroxyphenyl) propionate] methane (B) tetrakis [methylene (3,5-di-butylhydroxyphenyl) propionate] to 100 parts by weight of propylene homopolymer powder of (A) MFR 0.40, 2,6- Hinder consisting of 0.2 part by weight of di-t-butylcresol and 0.1 part by weight of 2,4-bis (normal-octylthio) -6- (4-hydroxy-3,5-di-butylamino) -1,3,5-triazine 0.33 parts by weight of dephenolic compound, (C) erucic acid amide (manufactured by NOF CORPORATION, trade name "Alflo P10" and a mixture of calcium stearate 2 to 8 0.40 to 1.0 parts by weight, (D) methylphenyl polysiloxane (Toshiba Silicon Brand name YF3918), 0.05 to 0.10 parts by weight is added and mixed for 2 minutes with a high speed mixer, then the caliber
Melt and knead at a temperature of 250 ° C using a 40 mm extruder to obtain MFR
To obtain a polypropylene resin composition of 0.43 to 0.48.

Using these polypropylene resin compositions, caliber 40m
m, L / D26 extruder and caliber 100 mm, lip clearance 1.0
Using a spiral die of mm, each inflation film (unstretched original fabric) was prepared by an air cooling method at a die temperature of 260 ° C.

After slitting these unstretched raw fabrics into 18 mm width tapes, the tapes were stretched 6 times using a roll stretching machine at a set temperature of 110 ° C, and then relaxed through a heated air bath at a set temperature of 160 ° C. Approximately 1500 after 10% annealing
Each flat yarn of denier was obtained. Subsequently, the stretching ratio of 6.5 times was similarly performed.

Subsequently, these polypropylene flat yarns were woven as a weft in a Sulzer fiber machine and woven with a structure of 15 × 15 / inch.

At this time, the extrudability of each polypropylene resin composition, the properties of the obtained polypropylene flat yarns, and the residual strength and strength retention rate of the weft yarns woven after weaving were evaluated.
Are shown in Table 1.

Example 5 (A) 0.10 parts by weight of (B) tetrakis [methylene 3,5-di-butylhydroxyphenyl) propionate] methane, 2,6-di- (B) per 100 parts by weight of propylene homopolymer powder of MFR0.40 t-Butylcresol 0.25 parts by weight, 2,4-
Bis (normal-octylthio) -6- (4-hydroxy-3,5-di-butylamino) -1,3,5-triazine 0.15
0.50 part by weight of a hindered phenolic compound consisting of 1 part by weight, (C) erucic acid amide (manufactured by NOF CORPORATION, trade name "Alflo P10", 0.20 part by weight of a mixture of calcium stearate 2/8, (D) methylphenylpolysiloxane (Toshiba Silicon Co., Ltd., trade name YF3918) 0.1 part by weight was added, and after mixing for 2 minutes with a high speed mixer, it was melt-kneaded at a temperature of 250 ° C. using an extruder with a diameter of 40 mm, and a polypropylene resin with MFR of 0.44. A composition was obtained.

Using this polypropylene resin composition, an inflation film was obtained in the same manner as in Example 1 and stretched and annealed.

Subsequently, this polypropylene flat yarn was used as a weft on a Sulzer loom and woven with a structure of 15 × 15 / inch.

Example 5 shows the extrudability of the polypropylene resin composition at this time, the physical properties of the obtained polypropylene flat yarn, and the residual strength and strength retention rate of the weft yarn after texture weaving.

Example 6 A polypropylene resin composition having an MFR of 0.89 was obtained in the same manner as in Example 1 except that (A) the propylene homopolymer powder had an MFR of 0.80. Using this polypropylene resin composition, an inflation film was obtained in the same manner as in Example 1 and stretched and annealed.

Subsequently, this polypropylene flat yarn was used as a weft on a Sulzer loom and woven with a structure of 15 × 15 / inch.

Example 6 shows the extrudability of the polypropylene resin composition at this time, the physical properties of the obtained polypropylene flat yarn, and the residual strength and strength retention rate of the weaved yarn after weaving.

Comparative Examples 1 to 3 Among the polypropylene compositions used in Example 1, the additive (B) content was insufficient, the additive (C) content was insufficient, and the additive (D) content was insufficient. Mix each polypropylene compound in a high speed mixer for 2 minutes and then calibrate 40
MFR was melted and kneaded at a temperature of 250 ° C using an extruder of
A polypropylene resin composition of 0.59 to 0.62 was obtained.

An inflation film was obtained using these polypropylene resin compositions in the same manner as in Example 1, and stretched and annealed.

Subsequently, this polypropylene flat yarn was used as a weft on a Sulzer loom and woven with a structure of 15 × 15 / inch.

Table 2 shows Comparative Examples 1 to 3 showing the extrudability of the polypropylene resin composition at this time, the physical properties of the obtained polypropylene flat yarn, and the residual strength and strength retention rate of the weft yarn that is diswoven after weaving.

Comparative Examples 4 to 6 (A) The propylene homopolymer powder was melt-kneaded in the same manner as in Comparative Examples 1 to 3 except that the MFR was 0.80.
A polypropylene resin composition of 0.89 to 0.93 was obtained.

Using these polypropylene resin compositions, an inflation film was subsequently obtained in the same manner as in Example 1, and stretched and annealed.

Subsequently, this polypropylene flat yarn was used as a weft on a Sulzer loom and woven with a structure of 15 × 15 / inch.

The extrudability of the polypropylene resin composition at this time, the physical properties of the obtained polypropylene flat yarn, and the residual strength and strength retention rate of the weaved yarn after weaving are shown in Table 2 as Comparative Examples 4 to 6.

Comparative Example 7 (A) The propylene homopolymer powder was melt-kneaded in the same manner as in Example 3 except that the MFR was 1.63, and the MFR was 1.72.
A polypropylene resin composition of was obtained. Using these polypropylene resin compositions, the die temperature was continuously raised to 24
An inflation film was obtained, stretched and annealed in the same manner as in Example 1 except that the temperature was 0 ° C.

Subsequently, this polypropylene flat yarn was used as a weft on a Sulzer loom and woven with a structure of 15 × 15 / inch. Comparative Example 7 shows the extrudability of the polypropylene resin composition at this time, the physical properties of the obtained polypropylene flat yarn, and the residual strength and strength retention rate of the weaved yarn after weaving as Comparative Example 7.

From the examples, the resin composition used in the present invention has a small load, pressure and ΔMFR at the time of melt extrusion and is excellent in extrudability, and the obtained polypropylene uniaxially stretched polypropylene flat yarn has high strength and high elongation. You can see what you are doing. Furthermore, it can be seen that the strength retention after disentanglement is large and the resistance to longitudinal cracking is excellent.

[Operation and effect of the present invention]

The polypropylene uniaxially stretched product of the present invention, for example, in the case of a polypropylene flat yarn, since a low melt flow rate resin composition having a specific additive is used as compared with the polypropylene flat yarn by the conventional resin composition, a uniaxially high strength is obtained. Although it is a stretched product, it also retains a high elongation.

Since it is a uniaxially stretched product that retains both high strength and high elongation at the same time, it has excellent properties that warp is unlikely to occur, and warps, twists, weaves, etc. until the commercialization. Deterioration of strength due to cracking is suppressed. For this reason,
The polypropylene uniaxially stretched product of the present invention can be expected to be sufficiently contributed to the final products such as bags, cloth sheets, ropes, nets and binding materials.

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Claims (1)

[Claims] (1) 100 parts by weight of (A) crystalline polypropylene, (B) hindered phenolic compound 0.10 to 1.0
A resin having a melt flow rate of 0.1 to 1.0 g / 10 min, which is prepared by blending 1 part by weight of (C) a fatty acid amide or a mixture of a fatty acid amide and a metal soap with 0.1 to 2.0 parts by weight, and (D) 0.01 to 0.50 part by weight of silicone oil. A polypropylene uniaxially stretched molded article obtained by uniaxially stretching the composition after extrusion molding.