JPS5911222A - Stretched tape - Google Patents

Abstract

PURPOSE:To obtain the stretched tape free from a flour bleeding, stretch cutting and useful for a cereal bag, etc., by melt extruding and stretching the compound containing PP and an ethylene-propylene block copolymer and having a specified melt index, ethylene content and infrared extinction ratio. CONSTITUTION:The compound which is obtained by blending a propylene homopolymer and an ethylene propylene block copolymer, has a melt flow rate (MFR) below 2g/10min, an ethylene content of 0.6-4.5wt% and 1.1-1.8 of an extinction ratio A720/A735 of an infrared absorption spectrum of 720cm<-1> and 735cm<-1> due to an ethylene measured at 130 deg.C is melt extruded and is made a film by an inflation method, etc., then it is slit, stretched, thereby obtaining the purpose stretched tape.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stretched tape, and more specifically, the present invention relates to a stretched tape, and more specifically, it is free from troubles during molding such as dusting and stretching breakage, and has excellent weaving resistance during weaving.
This invention relates to a high-strength polypropylene stretched tape with improved weave resistance.

Conventionally, stretched tapes made of polypropylene have been woven and often used for packaging materials such as grain bags and cement bags. In order to impart high strength to these polypropylene tapes, relatively high molecular weight polypropylene is used and stretched as high as possible. However, when stretched to a high magnification, stretch breakage occurs and operability decreases, and even when stretched to a high magnification, the strength reaches its peak and no improvement can be expected.Furthermore, damage during the weaving process causes significant weaving deterioration, resulting in high strength There was a problem that it was not possible to obtain a woven fabric.

In addition, polypropylene tapes are stretched and may cause MuJ distortion, which may cause weaving problems during the diameter adjustment and weaving processes and reduce operability. A method of blending polypropylene with elastomers, calcium carbonate, etc. has been proposed, but this is not sufficient to improve the separation resistance, and blending large amounts of these elastomers, calcium carbonate, etc. reduces the strength. , a problem arises in that film formability and stretchability deteriorate.

Therefore, the present inventors conducted intensive studies to solve the problems of the conventional polypropylene tape described above, and found that a composition with specific physical properties was created by blending an ethylene propylene block copolymer with a propylene pomopolymer. It was found that by forming a tape from this composition, a high-strength, low-shrinkage stretched tape with improved weaving resistance and weaving deterioration resistance was obtained without forming problems such as dusting and stretching breakage. Heading This invention has been made.

The stretched tape according to the present invention contains a propylene homopolymer and an ethylene propylene block copolymer and has a melt flow rate of 2 g (hereinafter referred to as MFR).
/ less than 10 m1n, ethylene content is 06 to 71.5% by weight, and infrared absorption spectrum based on ethylene measured in a melted state at 130 °C at 720 cm and 735 cm
A composition having an absorbance ratio A720/A735 of 11 to 18 is melt-extruded and stretched.

The present invention will be explained in more detail below.

As mentioned above, the composition containing a propylene homopolymer and an ethylene propylene block copolymer used in the present invention has a concentration of 2 g/kg at 230°C and 216 kg.
Less than 10m1n, preferably 05-15g/lo
has a M F' R of min, and the value of this V F R is 2.
If it exceeds 0.5 g/10 m1n, the strength will be insufficient and the deterioration of the weave will not be improved, making it impossible to obtain the desired stretched tape.On the other hand, if it is less than 0.5 g/10 m1n, there will be no problem with the strength and deterioration of the weave. 1. There is a difference in properties and stretchability. Further, the composition needs to have an ethylene content of 06 to 45%, and the ethylene content is 06% to 61%.
If the ethylene content is less than 45%, the effect of improving the weave separation resistance and the weaving deterioration resistance will not be sufficient, and the objective 1 of the present invention cannot be achieved.On the other hand, if the ethylene content exceeds 45%, the This is not preferable because the effect of improving the weaving property is saturated and various problems such as reduced strength, high shrinkage, and poor stretchability tend to occur.

Fourth, the composition used in the present invention has a composition of 04 to 0
Place the press-formed sheet to a thickness of 8 mm into a melting infrared cell,
After melting at 130°C for about 10 minutes,
Take Spec I Le in the range of 680Cm publication, 760Cr
The line connecting n' and 690cm' is the baseline, and 7
The absorbance ratio A720/A735 determined by measuring the absorbance at 20 cm, 'and 735 cm' must be 11 to 18. In the infrared absorption spectrum measured at 130°C, there is an absorption peak near <720cIrL-1, which is based on block ethylene with 1125 or more methylene chains, and 23 or less acH methylene chains. Based on random ethylene, it has an absorption peak around <735 cm, -', and the absorbance ratio A, 720/A735, indicates the degree of blocking of the ethylene distribution in the rubber part,
If this absorbance ratio is less than 11, due to the random nature of ethylene in the ethylene-propylene block copolymer, it will completely dissolve in the propylene homopolymer that is the base layer, and as a result, stretching This is not preferable because the tape's resistance to weaving and deterioration cannot be improved. On the other hand, if the absorbance ratio exceeds 18, the compatibility with the propylene homopolymer that is the base layer decreases, and a dusting phenomenon occurs in the film forming and stretching steps, which significantly impairs the operability, which is not preferable. As described above, the composition of the propylene homopolymer and the ethylene propylene block copolymer used in the present invention is made such that the composition of the propylene homopolymer and the ethylene propylene block copolymer used in the present invention has a specific range of MFR, ethylene content, and absorbance ratio. It is necessary to blend the ethylene propylene block copolymer and the ethylene propylene block copolymer, for example, by polymerization blending or pellet blending.

The propylene homopolymer constituting the composition is a conventionally well-known polymer, and various types of polymers are commercially available. In the present invention, any conventionally known propylene homopolymer can be used, but in particular, propylene homopolymers with an MF'R of 05 to 1.5 g/10m
Those in the range of 1n can be suitably used. The ethylene propylene block copolymer, which is the other component constituting the composition of the present invention, can be obtained by, for example, producing a propylene homopolymer or an ethylene propylene copolymer containing a small amount of ethylene in the first step, and producing ethylene propylene in the second step. It is a copolymer produced by a method such as polymerizing propylene copolymer rubber or polyethylene containing a small amount of propylene, and it contains block methylene chains and has improved impact resistance, especially MFRo, 5 to 1.5. g / ]00m
1 can be suitably used.

The composition of propylene homopolymer and ethylene propylene block copolymer used in the present invention includes, for example, an antioxidant (for example, 2,6-di-t-butyl-p-cresol), an ultraviolet deterioration inhibitor, a lubricant, and a pigment. Any additives conventionally commonly used for polyolefin compositions, such as, can be blended. In addition, compounding agents such as the above-mentioned calcium carbonate and elastomer may be added, and in some cases, the effects of the present invention may be further enhanced by the addition of such compounding agents.

The above-described propylene homopolymer and ethylene-propylene block copolymer are blended in such a proportion that a composition having the above-described specific MFR, ethylene content, and absorbance ratio can be obtained. Such blending can be performed by any conventionally known blending method. The composition thus obtained can be used, for example, by water-cooled inflation,
A film is formed using a general molding machine such as air-cooled inflation or T-die molding, and after film formation, for example, a hot roll stretching machine,
The tape was stretched at an appropriate ratio at high temperatures using a conventional stretching machine such as an oven stretching machine or a hot plate stretching machine, and then annealed to improve dusting, resistance to weaving, and resistance to fabric deterioration during tape molding. A stretched tape can be obtained.

Hereinafter, the present invention will be explained in more detail according to examples.
It goes without saying that the scope of the present invention is not limited to these Examples. In addition, MFR and density in the example are J I
According to SK6760.

Example 1 75 parts by weight of propylene homopolymer of MFRo, 79 g/]00ml and MFRo, 81g/]0r
nin, ethylene-containing it 8. 25 parts by weight of an ethylene propylene block copolymer containing 0% by weight were pellet blended. The physical properties of the obtained composition were as shown in Table 1.

Next, a film was formed by the inflation method, and after slitting the obtained film, it was axially stretched 7 times at a temperature of 130°C, and then tempered by 5% at a temperature of 135°C to a width of 7 mm and a 1.
000 denier stretched tape was woven into a plain woven fabric using a wrapping machine.

The physical properties of the obtained tape and woven fabric were measured by the following method,
The results are shown in Table 2, including the maximum stretching ratio as a reference value.

(a) Strength: JIS Z1533 Chuck interval 300mm Tensile speed 300mm/m1n (b) Elongation: Same as above (c) Shrinkage rate: 650mm (7) After leaving the sample in an air oven at 130°C for 10m1n (d) During molding Fluffing property: Visually observe the dusting on the stretching roll surface after 2 hours of running Observation ○...Good, ×...Poor (E) Weaving resistance: Inside the wire belt under a load of 0.1 g/d Total number of cracks in 10 samples when reciprocating 1000 times (f) Tensile strength of woven fabric JIS L 1068 (f) Weave deterioration rate: Examples 2 to 3 and Comparative Examples 1 to 5 In Example 1 The used propylene homopolymer and ethylene propylene block copolymer were polymerized and blended to obtain a composition as shown in Table 1. The physical properties of this composition were as shown in Table 1.

Next, using this composition, a stretched tape was produced in the same manner as in Example 1, and a woven fabric was woven. The physical properties of the obtained stretched tape and woven fabric were as shown in Table 2.

Comparative Example 6 A stretched tape was produced in the same manner as in Example 1 using a propylene homopolymer having the physical properties shown in Table 1, and a woven fabric was woven. The physical properties of the obtained stretched tape and woven fabric were as shown in Table 2.

Table 1 (11) As is clear from the Examples and Comparative Examples, the polypropylene cheese of the present invention has excellent strength, low shrinkage, dusting resistance, resistance to weaving, and resistance to weaving. If the flow rate is high, the strength and weave deterioration resistance will be poor; if the ethylene content is low, as in Comparative Example 2, the weaving resistance and weave deterioration resistance will be poor; and if the ethylene content is high, as in Comparative Example 3, the strength will be weak. If the shrinkage rate is high and the absorbance ratio A720/A735 is small as in Comparative Example 4, the weave separation resistance and weave deterioration resistance will be poor, and if the absorbance ratio A720/A735 is large as in Comparative Example 5, the stretchability and dusting property will be poor. As in Comparative Example 6, the propylene homopolymer has poor weaving resistance and weaving deterioration rate.

Patent applicant: Showa Denko Co., Ltd. Agent Sei Kikuchi (13)

Claims (1)

[Claims] 1. Contains propylene homopolymer and ethylene propylene block copolymer, melt flow rate (MFR)
less than 2 g/lomin, ethylene content 0.6
720CIrL and 735c of infrared absorption spectra based on ethylene measured at ~4.5% by weight and at 130°C.
A stretched tape obtained by melt extruding and stretching a composition having an absorbance ratio A720/A735 of m' of 1°1 to 18.