JPH02308839A - Polypropylene composition - Google Patents

Abstract

PURPOSE:To obtain a composition capable of providing a uniaxially drawn molded product having a high strength and elongation by blending high- molecular weight crystalline polypropylene with specific crystalline polypropylene. CONSTITUTION:A polypropylene composition obtained by mixing (A) 100 pts.wt. crystalline polypropylene having 0.3-2.0g/10min melt flow rate and 5-8 Q value with (B) 2-10 pts.wt. crystalline polypropylene, prepared by blending an organic peroxide with 100 pts.wt. component (A) and heat-treating the resultant blend and having 3-15g/10min melt flow rate and <=3.5 Q value. The component (B) is prepared by blending 100 pts.wt. crystalline polypropylene with 0.01-0.10 pt.wt. organic peroxide. Dialkyl peroxides are used as the organic peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel polypropylene composition that provides polypropylene stretched moldings with improved strength and elongation.

[Conventional technology]

Uniaxially stretched products such as flat yarns, tapes, monofilaments, and bands made of crystalline polypropylene (hereinafter sometimes simply abbreviated as PP) have excellent mechanical strength, so they can be used in various bags, cloth sheets, ropes, nets, etc. It is widely used as an industrial material such as binding material. As a method of increasing the strength of such a Kerr axis stretched molded product, attempts have been made to use PP with a higher molecular weight and stretch it at a higher magnification.

It is important to obtain an unstretched original fabric with uniform physical properties in order to facilitate high-magnification stretching.
When using a polyester, high flow resistance during melt extrusion is likely to cause surging and melt fracture, and it is difficult to obtain an unstretched original fabric with uniform surface condition and crystallinity, making it difficult to stretch at a high magnification. Therefore, in general, the maximum stretch ratio that can be stably produced is 6 to 7 times, and the strength is 5 to 7 f/d.
, the elongation is about 20-25%. If stretching is carried out at a high magnification, problems such as stretching breakage may occur, reducing productivity, and the resulting uniaxially stretched product will have a high Young's modulus and low elongation. Vertical cracks and fuzzing are likely to occur during processes such as - The strength improvement of axially stretched products cannot fully contribute to the strength improvement of final products such as bags, cloth sheets, twisted ropes, binding materials, etc. This is the reality.

In order to prevent longitudinal cracking of uniaxially stretched molded products, methods of adding calcium carbonate or rubber-like substances have been proposed, but this is not appropriate as it would reduce the strength.

[Problem to be solved by the invention]

An object of the present invention is to provide a polypropylene composition that eliminates the above-mentioned drawbacks of axially stretched polypropylene molded products and can yield polypropylene axially stretched molded products having high strength and high elongation.

[Means for Solving the Problems] As a result of intensive studies in order to solve the above problems, the present inventors blended a specific amount of a specific crystalline polypropylene (B) into a high molecular weight crystalline polypropylene/(A) to produce tafoliflopylene. The present invention was completed after learning that the intended purpose could be achieved by using composition (C).

That is, the present invention has a melt flow rate (hereinafter sometimes abbreviated as MFR) of 0°3 to 2.0f/10.
m1n % Crystalline polypropylene with a Q value of 5 to 8 (A
) 1001 parts by weight and 100 parts by weight of crystalline polypropylene are blended with an organic peroxide and heat-treated to obtain a melt flow rate of 3 to 15 f / l Om1n
Crystalline polypropylene composition (C) with an NQ value of 3°5 or less (hereinafter sometimes simply referred to as composition (C))
It is.

PP (A) used in the present invention is a normal crystalline polypropylene obtained by polymerizing propylene using a Ziegler-Natsuta catalyst or the like while controlling the molecular weight with hydrogen, and is not only a propylene homopolymer but also a propylene homopolymer. It may also be a copolymer of α-olefin such as ethylene or butene-1. Such PP usually has a Q value of 5 to 8, but in the present invention, the MFR is 0.3 to 2°0f710 m
Use the in one. Here, the Q value is Mw / Mn
(Mw is the weight average molecular weight, Mn is the number average molecular weight), and MFR is the condition 14 (230
℃, 2°16 kgf).

If the MFR exceeds 2.0, it is easy to obtain a homogeneous unstretched original fabric, but sufficient strength cannot be imparted even if this is stretched to a high ratio. Furthermore, if the MFR is less than 0.3, surging or melt fracture will occur during melt extrusion, and even if PPCB (described later) is used, a homogeneous unstretched original fabric cannot be obtained and high-stretching ratio cannot be achieved.

p P (B) used in the present invention is normal PP100
Add 1 to 0.10 parts by weight of organic peroxide per part by weight, and heat at 180 to 300°C using an extruder or the like for 2 to 10 parts by weight.
Heat treatment such as melting and kneading for 3 to 15 minutes
, the Q value was adjusted to 3.5 or less. Examples of the organic peroxide include dialkyl peroxides such as 2.5-dimethyl-2,5-t-butylperoxyhexene-3, and 2.5-dimethylhexane-2,5-sivitro-oxide. The amount of organic peroxide added and the conditions for heat treatment are determined by experiment, but the larger the amount of organic peroxide added, the larger the MFR and the smaller the Q value.

By blending an appropriate amount of such PP (B) with PP (A,), it is possible to improve the melt flowability of PP and obtain a homogeneous unstretched original fabric, and also improves the drawability, making it possible to Stretching becomes possible. When the Q value of p P (B) exceeds 3.5, the effect of improving melt fluidity and drawability cannot be obtained. P P (
Even if the Q value of B) is 3°5 or less, if the MFR is less than 3, the effect of improving melt fluidity and stretchability is insufficient.
When the MFR exceeds 15, the strength and elongation of the uniaxially stretched molded product obtained are insufficiently improved.

In the present invention, the composition (C) is prepared by blending 2 to 10 parts by weight of PP (B) with respect to the above PP (A)] and 1 corner of OO.
shall be. If the amount of PP (B) is less than 2 parts by weight, the improvement in melt fluidity and stretchability will be insufficient, and if it exceeds 10 parts by weight, the strength and elongation of the uniaxially stretched molded product will be insufficient.

The composition (C) of the present invention may contain various yuzu stabilizers, antistatic agents, pigments, fillers, etc., which are usually used in pp, to the extent that they do not impair the purpose of the present invention.

There is no particular limitation on the method of obtaining an axially stretched polypropylene molded product using the composition (C) of the present invention, and an unstretched original fabric is produced by a normal T-die method or an inflation method, and then cut into an appropriate width. With or without slits,
The film is stretched by a tenter method or a roll stretching method while being heated by a known method such as a heated roll method or a heated air bath method.

〔Effect of the invention〕

By using the composition (C) of the present invention, it is possible to stretch at a high magnification of 7 times or more, and the uniaxially stretched molded product obtained thereby also has high strength and high elongation, making it difficult to cause vertical cracking. It is extremely useful as a material for various bags, cloth sheets, ropes, batts, binding materials, etc.

〔Example〕

The present invention will be explained in more detail with reference to Examples and Comparative Examples. The test methods used by each side are as follows.

MFR+J engineering 5K1210 (thermoplastic furano-f-
Flow test method), condition 4 (230'C.

2.16kgf) According to K. Unit f/10mln
Strength/Elongation: JIS L Yuo13 (chemical fiber filament yarn test method), grip spacing 20C: In.

Based on the tensile speed of 20α/m and nVc. Unit: Strength g/d1
Elongation Q value: Based on gel permeation shot chromatography.

Example 1.2 To 0 parts by weight of propy L/7 homopolymer powder with M F R1,3 and a Q value of 6.8, 2 parts by weight of 2+6-di-t-butylcresol, 2 parts by weight of tetrakis[methyl 1/n] (3,5-sheptylhydroxyphenyl)propionate] 0.10i-15 parts of methane, stearin M force/L = sium o. ", FIL and 0.02 parts by weight of bis(t-butylperoxyisopropyl)benzene were added, mixed for 2 minutes with a high-speed mixer, and melt-kneaded at 240'C using an extruder with a diameter of 40 mm. A PP (B) pellet with a JboF R of 14.4 and a Q value of 3.4 was obtained.

M F RO, 35, Q value 6.7 PP (AllOOi
10 parts by weight of the above pp(:s) pellets were added to part ii and mixed for 1 minute using a high speed mixer to obtain a composition (C).

This composition (C) had a diameter of 40'l and a L/D of 2
A blown film (unstretched original film) was prepared by an air cooling method using an extruder No. 6 and a spiral die having a diameter of 100° C. and a lip clearance of 1.0 m.

This unstretched original fabric was slit to make a tape with a width of 15 mm.
A flat yarn of approximately 100 denier was produced by drawing the yarn at a drawing temperature of 125° C., followed by annealing at a relaxation rate of 10% through a heated air bath at 150° C. Table 1 shows the composition of this composition (C), the maximum stretching ratio that could be stably produced without causing stretch breakage, and the strength and elongation of the obtained flat yarn.

Example 3.4 The same procedure as in Example 1 was carried out except that a 70-bin homopolymer with M F Ro, 52 and a Q value of 6°6 was used, and the amount of organic peroxide added was 06022 parts by weight. , MFR6゜9, Q
A value of pp(r+) of 2.9 was obtained.

M F Tt O, 9, Q value 6.5 PP (A) 100
Example 1: 5N parts of the above PP (B) was added to one rope part.
Composition (C) was obtained by mixing in the same manner as in Examples 1 and 2, and a flat yarn was produced from the unstretched raw fabric in the same manner as in Examples 1 and 2. These results are shown in Table 1.

Example 5.6 M F T(3,2
, a pellet of PP(B) with a Q value of 2.5 was obtained.

5 parts by weight of the above PP (B) was blended with 100 parts by weight of PP (A) having a M F R of 3,2 and a Q value of 6°2, and the following Example 1 was prepared.
．． A flat yarn was produced in the same manner as in Example 2.

These results are shown in Table 1.

Comparative Examples 1 to 6 Using various PPCAs used in Examples 1 to 6, PP(
An undrawn original fabric was obtained in the same manner as in Example 1.2 without blending B), and then a flat yarn was produced. These results are shown in Table 1.

Comparative example 7.8 MF RO, 82, Q value 6,5+7) PP(A) 10
0 parts by weight, PP (B
A flat yarn was produced in the same manner as in Examples 1 and 2 using a composition (C-1) obtained by blending 5 parts by weight of -1). These results are shown in Table 1.

Comparative Example 9, using a propylene homopolymer with lO M F R 1.40 and Q value 6.2, and melt-kneading in the same manner as in Example 1 except that the amount of organic peroxide added was 0.012 parts by weight. As a result, pp (B-2) with an MFR of 6°l and a Q value of 6°5 was obtained. MFRO
, 82, using a composition (C-2) obtained by blending 5 parts by weight of the above PP (B-2) to 0 parts by weight of p P (A, + l O) with a Q value of 6.5, Flat yarns were produced in the same manner as in Example 1.2.The results are shown in Table 1.

Comparative Example 11.12 A propylene homopolymer with MFRO Yu35 and a Q value of 6.7 was used, and melt-kneaded in the same manner as in Example 1 except that the amount of organic peroxide added was 0.016 parts by weight. M F R2,
5. PP (B-3) with a Q value of 3°l was obtained. MFRO03
5. A composition (C-3) obtained by blending 5 parts by weight of Disembarked PP (B-3) with 100 parts by weight of PP (A) with a Q value of 6°7.
), a flat yarn was produced in the same manner as in Example 1.2. These results are shown in Table 1.

Procedural amendment

Claims (2)

[Claims] (1) Melt flow rate is 0.3-2.0g/10m
in, crystalline polypropylene (A) 10 with a Q value of 5 to 8
Crystalline polypropylene (B ) 2 to 10 parts by weight of a polypropylene composition for stretch molding. (2) Crystalline polypropylene (B) contains 0.01 to 0 organic peroxide per 100 parts by weight of crystalline polypropylene.
．． The polypropylene composition according to claim (1), which is obtained by blending 10 parts by weight.