JPS6065007A - Crosslinkable/expandable propylene/butene copolymer - Google Patents

Abstract

PURPOSE:The titled copolymer excellent in crosslinkability and suitable for forming fine closed cells when expansion-molded, containing a specified crystalline propylene/butene-1 copolymer as an effective component. CONSTITUTION:The titled copolymer having, as an effective component, a crystalline propylene/butene-1 random copolymer having a butene content of 5- 30wt%, a crystallinity of 0.65-0.90 and a melt index of 0.3-30g/10min. A PP foam is more excellent in properties such as heat resistance, chemical resistance, and strength than a PS foam and is more suitable for use in automotive interior trims, household articles, building materials, etc. However, when a commercially available PP is heated to a temperature above the m.p., the molten resin can not hold a gas generated from a blowing agent in a state of fine and uniform cells. By using the above copolymer, it is possible to obtain a crosslinked foam of excellent properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a propylene-butene-1 copolymer for crosslinking and foaming. More specifically, 1 the present invention provides a copolymer which has a copolymer component content, mel I index and crystallinity within a specific range, has excellent crosslinking properties, and is suitable for forming fine closed cells during foam molding. Regarding merging.

Polypropylene foam is superior to polyethylene foam in physical properties such as heat resistance, rigidity, and tensile strength, and superior to polystyrene foam in physical properties such as heat resistance, chemical resistance, and strength, and is therefore used for automobile interior parts,
Suitable for various uses such as household goods and building materials.

By the way, since the melt viscosity of ordinary commercially available polypropylene is highly dependent on temperature, when it is heated above its melting point, the gas generated from the blended blowing agent etc. cannot be contained in the molten resin in the form of fine and uniform bubbles. Therefore, there is a way to reduce the temperature dependence υ.

A technique for crosslinking polypropylene is known as However, when ordinary commercially available polypropylene is melt-kneaded with a blowing agent or radical generator, or crosslinked with ionizing radiation, etc., the degree of crosslinking is small; In some cases, there is a drawback that a uniform foam cannot be formed because of partial foaming or crosslinking.

The following invention is known as a foaming propylene-based, lti polymer, or a composition of the copolymer and another polymer.

Namely, Special Public Interest Publication No. 4l-126311j, No. 54-3
The invention of No. 1498 describes the use of polypropylene and a propylene-ethylene copolymer composition, and the use of a mixture of polystyrene or butadiene-styrene copolymer with this composition. However, the foaming method for these compositions is different from the method for processing the copolymer of the present invention in that the foaming agent is mixed with the composition, the composition is heated and melted, and then extruded and foamed, and is not a crosslinking foaming method. Ru.

Moreover, a copolymer different from the propylene-butene-1 copolymer of the present invention is used.

The inventors have worked hard to develop a propylene polymer for crosslinking and foaming that maintains the above-mentioned excellent physical properties of polypropylene foam and is free from the above-mentioned drawbacks in terms of foam formation. Researched. As a result, the present invention was completed based on the knowledge that the above-mentioned problems could be solved by using a copolymer of propylene and butene-1 having the following composition, melt index, and crystallinity.

As is clear from the above description, an object of the present invention is to provide a propylene-butene-1 copolymer from which a polypropylene-based highly foamed material with excellent physical properties can be obtained by a crosslinking foaming method. Another object is to provide a crosslinked foam obtained using the copolymer.

The present invention has the following main configuration (1).

(1) Butene content 5-30% by weight, crystallinity 0.6
5-0.90 and melt index 0.3-30g
/10 minutes A propylene-butene copolymer for crosslinking and foaming, the active ingredient being a crystalline propylene-butene-1 random copolymer.

The structure and effects of the present invention will be explained in detail below.

The method for producing the propylene copolymer used in the present invention is not new, for example, Japanese Patent Publication Nos. 47-11806 and 57-57.
tJ can be manufactured by the method described in No. 39842 or No. 5B-4923.

The degree of crystallinity referred to in the present invention is measured by infrared analysis. The in-body measurement method involves measuring the sample to a desired thickness (for example, 40 mm).
This specimen was heat-treated at 135°C for 15 minutes, and the spectrum of the heat-treated product was absorbed by infrared absorption method, and the wave numbers of the spectrum were 977C''-' and +19.
7c''-' absorbance ratio (997''/977''-1
). Of course, a large value means a high degree of crystallinity. For example, the case of ordinary commercially available crystalline polypropylene (homopolymer) is 0.94
~0.98.

The butene used in the copolymer of the present invention is butene-
1 is preferred. The butene content of the propylene-butene-1 random copolymer is 5 to 30% by weight (hereinafter referred to as %), and the crystallinity is 0.65 to 0.90. The amount of butene corresponds to the degree of crystallinity, and as the amount of butene increases, the degree of crystallinity decreases. The amount of butene is less than 5 and the crystallinity is 0.
．． If it exceeds 90, the crosslinkability of the copolymer will be poor, making uniform and fine foam molding impossible. In addition, partial foaming or crosslinking occurs during melt mixing or crosslinking treatment, which is undesirable.On the other hand, if the butene content exceeds 302 and the crystallinity is less than 0.85, the physical properties of the final foamed material will change. The properties of polypropylene foam are lost in terms of heat resistance and other aspects.

The melt index of the copolymer for use in the present invention is J l5
It was measured by the method of K8758. This value is 0
．． If it is less than 3, the blowing agent or radical generator will decompose during melt-kneading for foam molding, causing partial foaming or crosslinking, which is not preferable. On the other hand, if this value exceeds 30, the flow during melting will be too good, resulting in poor melt-kneading properties and poor extrudability.

When producing a cross-linked foam using the copolymer of the present invention, other thermoplastic resins or rubber-like materials may be mixed with the composition by up to 50 times, preferably up to 35 times. If the mixture exceeds 5 (H), the physical properties specific to polypropylene will be lost in the final foamed molded product.

The copolymer of the present invention can be used by replacing the 491 or less stars with the following copolymer B or C, which was unknown in terms of the purpose of the invention at the time of filing of this application.

B: Combined ethylene content 0.5 to 1 oz, butene content 3
~20% by weight, a crystallinity of 0.85-0.90 and a melt index of 0.3-30 g/10 min.

C: According to ethylene content 3 to 3 oz, melt index 0.3 to 30 g/10 minutes, and thermal analysis method, 1
2 (ethylene propylene random ethylene propylene with one endothermic peak at 1~130℃ and 140~180℃)
Block copolymer.

For the copolymer of the present invention or a composition in which the copolymer is mixed with another thermoplastic resin or rubber-like material, a heat stabilizer commonly used for polypropylene can be used. They are, for example, butylated hydroxytoluene (BHT), tetrakis[methylene-3-(3').

5'-di-t-butyl-4'-hydroxyphenyl) propionate comethane, 4,4-biphenylene diphosphinic acid tetrakis (2,4-di-t-butylphenyl)
etc. These can be incorporated into the copolymer or copolymer composition of the present invention, singly or in combination of two or more. The blending amount is 1:0.05 to the copolymer, etc.
1.5$ is better, preferably 0-1 to 1.0% teal. 0.05
If the temperature is less than z, the copolymer etc. are likely to be thermally deteriorated, and 1. ! Even if the IJ is exceeded, the thermal stability does not particularly improve, and in either case, the crosslinking rate decreases.

The copolymer or copolymer composition of the present invention can contain inorganic fillers and pigments that are used in known polypropylene compositions. The copolymer composition of the present invention prepared as described above can also be used for foam molding by a foaming method other than crosslinking foaming according to the present invention. These are, for example, waste injection foaming, gas impregnation foaming (bead foaming), conventional extrusion foaming with chemical blowing agents.

The crosslinking and foaming method referred to in the present invention is the same as a known method as exemplified in the following implementation sections.

In addition, the degree of crosslinking (gel fraction) on each side refers to the foamed product (
This is the value expressed in % of the amount remaining after boiling point extraction of the resin) with xylene at 120° C. for 24 hours.

Examples 1-3. Comparative Examples 1-3 Butene-1 content 5,15.25L Crystallinity 0.71-0
．． Propylene/butene-1 binary random copolymer powder with 89° melt index 13g710min,
azidicarbonamide 1oz, divinylbenzene (pure 1
ff60%) 5X, BIT O, 5L Sufu 7! J
7 acid power) It thiium 0. H was added and mixed using a Henschel mixer. This mixture was extruded using a 50mm diameter extruder under conditions where the resin temperature did not exceed 170°C @300+w
, m, and was molded into a sheet with a thickness of one layer. In this sheet, the foaming agent was uniformly dispersed in an unfoamed state.

The sheet was heated to 5.5M using an electron beam accelerator (bump rough type).
After irradiating both sides at a rate of rad, foaming was carried out in a foaming tank heated to 220°C. The product obtained was a white sheet-like foam with fine bubbles. As a comparative example, a 5z product with butene-I of 0.3.5% has a crystallinity of 0.91 and an example.
Tests were conducted in the same manner as in Examples 1 to 3 using a material with a value higher than 0.88 of 1. The obtained product had a low gel fraction and a high density, and the appearance of the foamed product was poor in the uniformity of the cells and the surface was uneven.

The results are shown in the table.

Table 1 Examples 4 to 10. Comparative Examples 4 and 5 The same polymer as in Example-1 was used, and polyethylene (melt index 2.0 g/10 m1n,
8 degrees 0.917 g/cm3. Asahi Kasei (formerly 820),
! Chi L/7 vinyl acetate copolymer (melt index 2.5g/10+in density, O40g/crn', Mitsui Polychemical ■460), ethylene-propylene rubber (Mitsui Petrochemical ■Tafmer PO380) 15-5
Teston was prepared in the same manner as in Examples 1 to 3, with the addition of 0%. For comparison, a product to which 802% of polyethylene or the like was added was tested.

Foamed products with good appearance were obtained in both Examples and Comparative Examples, but the Comparative Example products in which 60wtX of polyethylene etc. were added lacked rigidity and lost the characteristics of PP foamed products.

The results are shown in Table 2.

Claims (1)

[Claims] (4) Butene content: 5 to 30% by weight, crystallinity: 0.8
5-0.90 and melt index 0.3-30
A propylene butene copolymer for crosslinking and foaming, the active ingredient being a crystalline propylene φ butene-1 random copolymer having a molecular weight of 1 g/10 min.