JP2659371B2 - Crystalline ethylene / propylene block copolymer composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a crystalline ethylene / propylene block copolymer composition.

[Conventional technology]

The crystalline ethylene / propylene block copolymer has high rigidity and is excellent in balance with impact resistance.
However, the crystallization rate is relatively slow, and depending on the application, there are problems such as low crystallinity after molding and low rigidity, and the large spherulite diameter impairs transparency, and the like. If the speed is increased, there is a problem that the balance between rigidity and impact resistance is inferior.

Several attempts have been proposed to increase the crystallization rate for the above disadvantages. For example, aromatic carboxylic acids, sorbitol derivatives (JP-B-55-12460, JP-A-58-129036)
It is known that, when (A) or the like is added to a propylene-based polymer, these act as a crystal nucleating agent, thereby improving the crystallinity and decreasing the crystal diameter. These crystal nucleating agents show excellent nucleating action and can increase rigidity and transparency. Receive. Also, the rigidity and transparency are improved, but the impact strength is reduced.

Japanese Patent Application Laid-Open No. Sho 61-61 discloses a method in which a crystalline propylene polymer crosslinked with a crosslinking agent of a polyfunctional allyl compound such as triallyl cyanurate in the presence of an organic peroxide is added as a crystal nucleating agent. It is shown in 16944.

According to the description of JP-A-61-16944, when an additional test was conducted with a crystalline ethylene / propylene block copolymer, the crystallization rate of the crystalline ethylene / propylene block copolymer was increased, and the rigidity was improved. Although there was a problem, the impact resistance was reduced, and the cross-linking agent exhibited a pale yellow color, and the hue of the resin deteriorated as the amount of the cross-linking agent added increased.

On the other hand, a crosslinkable propylene polymer obtained by grafting an ethylenically unsaturated silane compound to a propylene polymer and highly crosslinking by a water crosslinking method (JP-A-57-12051) is known. In this method, a highly crosslinked network is formed in a matrix in order to obtain heat resistance, and the melting temperature is increased to maintain heat deformation. Such a highly crosslinked resin has low melt fluidity, and it is very difficult to process it.

[Problems to be solved by the invention]

An object of the present invention is to provide a crystalline ethylene / propylene block copolymer composition having an excellent balance between rigidity and impact resistance.

[Means for solving the problem]

The present inventors have conducted intensive studies on a formulation for improving the crystallization rate, rigidity and impact resistance of a crystalline ethylene / propylene block copolymer and improving the melt fluidity, and as a result, a specific crystalline ethylene / propylene The present inventors have found that a composition comprising a crosslinked product of a block copolymer with a silane compound and a crystalline ethylene / propylene block copolymer can solve the above problems, and have completed the present invention.

That is, in the present invention, an ethylenically unsaturated silane compound is grafted with an organic peroxide to (b) the crystalline ethylene / propylene block copolymer with respect to (a) 100 parts by weight of the crystalline ethylene / propylene block copolymer. An ethylene / propylene block copolymer composition characterized by containing 1 to 50 parts by weight of a crosslinked copolymer having a gel fraction of 5 to 50% by weight which has been subjected to water crosslinking in the presence of a silanol condensation catalyst.

The crystalline ethylene / propylene block copolymer used in the present invention is obtained by polymerizing propylene using a stereoregular catalyst to obtain 55 to 95% by weight of the whole polymer, and then mixing propylene and ethylene at a weight ratio of 90/90. It is polymerized so that the ethylene content is 10 to 40/90 and the ethylene content is 5 to 40% by weight of the total polymer, and the intrinsic viscosity [η] measured in tetralin at 135 ° C. is 1
~ 4 dl / g, and those having a crystallinity of 30-60% as measured by X-ray diffraction.

The crosslinked copolymer as the other component used in the present invention is a crystalline ethylene / propylene block copolymer (which may be the same as or different from that used in the compounding, but is preferably the same as above). After grafting an ethylenically unsaturated silane compound with an organic peroxide, water-crosslinking is carried out in the presence of a silanol condensation catalyst, and the gel fraction thereof is preferably in the range of 5 to 50% by weight. If the gel fraction is 5% by weight or less, the impact resistance is not sufficiently improved, and if it exceeds 50% by weight, the melt fluidity of the composition is reduced, and the flow of the molten resin during molding processing becomes uneven, or the processed product May be deformed, and furthermore, a problem that fish eyes are formed in the product may occur.

The grafting reaction of the ethylenically unsaturated silane compound onto the crystalline ethylene / propylene block copolymer may be performed, for example, under melt kneading with an extruder, a kneader or the like, or may be performed in a solution state.

The silanol condensation catalyst may be previously blended with the ethylenically unsaturated silane compound and the organic peroxide, or may be added to the ethylenically unsaturated silane compound-modified ethylene propylene block copolymer after the graft reaction.

Exposure to water for obtaining the crosslinked copolymer (b) may be carried out by contacting water at room temperature to about 100 ° C. for about 1 hour to 1 day.

The ethylenically unsaturated silane compound used in the present invention, the general formula _{RSiR 'n R "3-n} ( wherein, R represents an ethylenically unsaturated hydrocarbon radical or hydrocarbonoxy radical, R'
Is an aliphatic hydrocarbon group, R ″ is a hydrolyzable organic group, and n is 0 to 2.) Specifically, for example, R is vinyl, allyl, Butenyl, cyclohexenyl, cyclopentadiel, γ-
Methacryloxypropyl, γ-acryloxypropyl,
m, p-styrylethyl and the like, wherein R ′ is methyl,
Groups such as ethyl, propyl, and phenyl;
Is an alkoxy group such as methoxy and ethoxy, an acyloxy group such as formyloxy and acetoxy, an oxime group, and an allylamino group. Particularly preferred is α-methacryloxypropyltrimethoxysilane.

The appropriate amount of the silane compound to be added to the crystalline ethylene / propylene block copolymer is 0.1 to 10 parts by weight based on 100 parts by weight of the crystalline ethylene / propylene block copolymer.

Examples of the organic peroxide used in the present invention include 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, 1,1-di (tert-butyl peroxide) -3,
3,5-trimethylcyclohexane, dicumyl peroxide, α, α'-bis (tert-butyloxydiisopropyl) benzene, tert-butylperoxycumene and the like.

An appropriate amount of the organic peroxide is 0.01 to 2 parts by weight based on 100 parts by weight of the crystalline ethylene / propylene block copolymer.

In addition, the crystalline ethylene / propylene block copolymer, the silane compound and the organic peroxide can be blended by a known method. Further, the same applies to the case where a silanol condensation catalyst is previously blended and the case where various known antioxidants, neutralizers, ultraviolet absorbers, antistatic agents, inorganic or organic fillers, etc. are blended as necessary. Method. For example, the above mixture is mixed and mixed by a Henschel mixer, a ribbon blender or the like.

As the silanol condensation catalyst, a catalyst that promotes the dehydration action between silicone and silanol is used.For example, dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dioctyltin dilaurate, lead naphthenate, cobalt naphthenate Organic salts such as carboxylate, ethylamine, hexylamine, dibutylamine and piperidine, and inorganic acids and fatty acids. Preferably, it is an organic tin compound such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate. The amount used is suitably 0.01 to 5 parts by weight based on 100 parts by weight of the silane compound-modified ethylene / propylene block copolymer.

The preparation of the crystalline ethylene / propylene block copolymer composition of the present invention is performed by blending by a known method. For example, (a) a crystalline ethylene / propylene block copolymer, (b) a crosslinked copolymer, and additives appropriately compounded as needed are mixed with a ribbon blender, a V-type blender, a Henschel mixer, and the like. It is prepared by kneading with a kneader or an extruder or by further pelletizing. Examples of the kneader used here include a Banbury mixer and a roll kneader. As the extruder, a twin-screw extruder can be used in addition to a single-screw extruder.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

Incidentally, the physical property measurement test in the present invention was conducted using ASTM D-790 for flexural modulus and AST for Izod impact strength.
MD-256, ASTM D-638 for tensile yield strength, ASTM D-648 for heat distortion temperature, ASTM D-1238 for melt index, gel fraction, crystallization rate (t _1/2 ) and DSC was measured based on the following method.

(1) Gel fraction (% by weight) 5 g of the crosslinked copolymer was extracted with meta-xylene using a Soxhlet extractor for about 24 hours, the weight of the extraction residue was measured, and the gel fraction was determined by the following formula.

(2) Crystallization rate (t _1/2 ) Using a crystallization rate measuring apparatus (MK-701 type manufactured by Kotaki Seisakusho Co., Ltd.) with a depolarization intensity method equipped with a scattered light compensation mechanism, sample thickness 0.2 mm, melting The half-crystallization time was measured under the conditions of a temperature of 210 ° C., a melting time of 4 minutes, an initial light source voltage of 3.2 V, and a crystallization temperature of 130 ° C.

(3) DSC Differential scanning calorimetry (DSC) is a PerkinElmer DSC
Crystallization temperature (Tc) of about 5 mg of sample using -4 system
Is maintained at 240 ° C for 10 minutes to completely dissolve the sample, and then the temperature is lowered at a rate of 10 ° C / min.
It was measured at ° C / min.

Examples 1 to 3 Ethylene content 10.5%, [η] 1.40 dl / g, melt index 7.7 g / 10 min, t _1/2 19.1 min, Tc and Tm were each 11
Α-methacryloxypropyltrimethoxysilane was added to 100 parts by weight of a crystalline ethylene / propylene block copolymer (hereinafter referred to as (a) -1) at 2.5 ° C and 158.4 ° C.
5 parts by weight, 0.1 parts by weight of benzoyl peroxide and 0.05 parts by weight of dibutyltin dilaurate were added, and mixed with a Henschel mixer.
After melt-kneading at 240 ° C, granulation was performed. After that, add 10
Exposure for a time gave a crosslinked copolymer (hereinafter referred to as (b) -1).

The gel fraction of (b) -1 was 7.0% by weight, the melt index was 4.1 g / 10 minutes, and the Tc was 123.6 ° C.

Next, 0.1 part by weight of tetrakis [methylene- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane and 0.1 part by weight of calcium stearate were added as stabilizers to 100 parts by weight of (a) -1 and granulated. (Hereinafter, this is referred to as (a) -2).

The above (a) -2 and (b) -1 are replaced by (a) -2 / (b) -1
At a weight ratio of 95/5, 90/10 and 80/20, respectively.
The mixture was mixed in a mold blender and melt-kneaded at a cylinder temperature of 240 ° C. using a 40 mmφ single-screw extruder to perform granulation.

 Table 1 shows the measurement results of various physical properties of the composition.

Examples 4 to 6 (a) -1 To 100 parts by weight of α-methacryloxypropyltrimethoxysilane, 1.0 part by weight, 0.15 parts by weight of benzoyl peroxide and 0.1 part by weight of dibutyltin dilaurate were added, and mixed with a Henschel mixer. Using a screw extruder, after melt-kneading at a cylinder temperature of 240 ° C, granulating and grafting the silane compound, 10
Exposure for a time gave a crosslinked copolymer (hereinafter referred to as (b) -2).

(B) -2 had a gel fraction of 15% by weight, and its melt index and Tc were 3.1 g / 10 minutes and 127.2 ° C., respectively.

Hereinafter, a composition was obtained in the same manner as in Examples 1 to 3, except that (b) -2 was used instead of (b) -1, and various physical properties were measured. Table 1 shows the measurement results.

Comparative Example 1. Various physical properties of (a) -2 in which no cross-linked copolymer was added were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 2 to 4 (a) -1 2 parts by weight of triallyl cyanurate and 0.03 part by weight of dicumyl peroxide were added to 100 parts by weight, mixed with a Henschel mixer, and then mixed at a cylinder temperature of 240 ° C. with a 40 mmφ single screw extruder. The mixture was melt-kneaded and granulated to obtain a crosslinked copolymer (hereinafter referred to as (b) -3).

The gel fraction of (b) -3 was 0.8% by weight, the melt index was 12.6 g / 10 minutes, and the Tc was 122.5 ° C.

Hereinafter, a composition was obtained in the same manner as in Examples 1 to 3, except that (b) -3 was used instead of (b) -1, and various physical properties were measured. Table 1 shows the measurement results.

Comparative Example 5 Diallyl maleate 2 in place of triallyl cyanurate
A crosslinked copolymer (hereinafter referred to as (b) -4) was obtained in the same manner as in Comparative Example 2 except for using parts by weight.

The gel fraction of (b) -4 was 0.3% by weight, the melt index was 12.0 g / 10 minutes, and the Tc was 122.3 ° C.

Hereinafter, a composition was obtained in the same manner as in Comparative Example 2 using (b) -3 in place of (b) -1 and various physical properties were measured. Table 1 shows the measurement results.

[Effects of the Invention] As shown in Table 1, the composition of the present invention has excellent rigidity and impact resistance, has a sufficiently high heat distortion temperature, has a good balance of physical properties, and is extremely valuable in industrial use. high.

Claims (1)

(57) [Claims] 1. An ethylenically unsaturated silane compound is grafted onto (a) a crystalline ethylene / propylene block copolymer with an organic peroxide with respect to (a) 100 parts by weight of a crystalline ethylene / propylene block copolymer. An ethylene / propylene block copolymer composition containing 1 to 50 parts by weight of a crosslinked copolymer having a gel fraction of 5 to 50% by weight which is then water crosslinked in the presence of a silanol condensation catalyst.