JPS603096B2 - Polyethylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and composition for improving crosslinked low density polyethylene.

It is known to improve the properties of polyethylene and other olefin polymers by crosslinking them under the action of free radical generators, such as organic peroxides.

However, the production of crosslinkable substances by this method involves considerable difficulty in implementation because the treatment method requires strict control. If overtreated, the polyolefin will crosslink prematurely and solidify in the extruder, making subsequent removal of the crosslinked product difficult and delayed. In addition, the crosslinked products of low density polyethylene show improvements in heat resistance, mechanical strength, stress cracking resistance, etc. compared to those before crosslinking, but the properties do not exceed the range of low density polyethylene. Therefore, flame retardancy cannot be imparted through crosslinking.

Therefore, a method of imparting flame retardance to low density polyethylene by adding chlorinated polyethylene, which has flame retardancy, to low density polyethylene has been considered. However, the method of crosslinking resin compositions made by adding chlorinated polyethylene or ethylene-vinyl acetate copolymer to low-density polyethylene under the action of organic peroxides is difficult, as well as the organic peroxides of various resins. Problems arise in extrusion processability due to differences in reactivity to

As a result of intensive research into these problems, the present inventors have discovered a completely new method. Furthermore, in order to improve the compatibility between the low-density polyethylene composition and the chlorinated polyethylene composition and to further impart flexibility, a resin key component to which ethylene-vinyl acetate copolymer is added is cross-linked. It is.

When describing the present invention, firstly, the density is 0.915 to 0. 0ta'
Low-density polyethylene with agglomerates has the general formula RR'SiY2
(In this formula, R is an olefinically unsaturated monovalent hydrocarbon group or a hydrocarbonoxy group, each Y is a hydrolyzable organic group, and R' is a group R or a group Y). The silane and 14 are reacted at a temperature of ◯ or higher in the presence of a free radical generator whose half-life at the reaction temperature is 6 minutes or less (this is referred to as step 1).

For 10 parts by weight of the product (1) obtained in step A,
Using chlorinated polyethylene having a density of 1.100 to 1.750 mm/kg and a chlorine content of 10 to 80%, add 50 to 20 parts by weight of the product obtained by the above step A. . This can be a real bet, but in order to further improve the compatibility with the low-density polyethylene composition and the chlorinated polyethylene composition to increase mechanical strength and impart flexibility, the density is 0.920-0. Add 0 to 100 parts by weight of the product (2) obtained in step A using an ethylene-mono-pinyl acetate copolymer with a pinyl acetate content of 5 to 45% and mix uniformly. Resin composition (2) is obtained. Next, by exposing the resin composition (1) to water in the presence of a silanol condensation catalyst (this is called process 2), it has good flame retardancy, flexibility, and stress cracking resistance that are not found in cross-linked low-density polyethylene products. This makes it possible to obtain polyethylene crosslinked molded products with If the amount of product (①) added is less than 5 parts by weight, it will have almost no effect on flame retardancy, and if it is more than 200 parts by weight, the good processability of low-density polyethylene will not be utilized, and the heat resistance will decrease. Therefore, 50 to 200 parts by weight is appropriate. In addition, although the amount of product (1) added can withstand use even without the addition, adding the product (2) improves the coherence between the product (2) and the product (2) and improves mechanical strength. Compositions with different flexibility can be made depending on the amount, but the amount added is 1
It is desirable that the amount is 0 parts by weight or less.

To describe the present invention in more detail, the low-density polyethylene used has a density of 0.915 to 0.940 ta's, and when measured according to JISK-6760, the Those having a melting index are suitable; those having a melting index of 0.5 or less than 8 will be difficult to mold when made into a resin composition.

In addition, the chlorinated polyethylene used has a density of 1.100 to 1.
．． It has a chlorine content of 10 to 80% and a molecular weight of 15×1 or less. Furthermore, the ethylene-vinyl acetate copolymer that can be used has a density of 0.920 to
0. It is suitable that the vinyl acetate content is 5 to 45% at pseudo 0 m/g and the melting index measured by the above-mentioned method is at least 0.5 m/lq min. In the general formula of the silane used in the present invention, R is a monovalent olefinically unsaturated group composed of carbon, hydrogen, and optionally oxygen. Examples of such groups are vinyl, allyl, butenyl, cyclohexenyl, cyclobentadienyl, cyclohexagenyl, C ratio=C(CH3)COO(CH2)3-, CH2
=C(CH3)COOCQCH20(C ratio)3- and.

Among these, a vinyl group is preferred. The group Y can be any hydrolyzable organic group; for example an alkoxy group such as the methoxy, ethoxy and butoxy group; an acyloxy group such as a formyloxy, acetoxy or propionoxy group; an oxime group such as 1ON═C(Cmelon)2, 1ON=C(CH3)C
24 and -ON=C(C6day5)2: or substituted amino/groups such as -NHCH3, -NHC2 and -NH(
C6 day 5) are alkylamino and arylamino groups. In a given silane molecule, each substituent Y may be the same or different. The group R' can be a monovalent hydrocarbon group containing no fatty unsaturation, such as methyl,
Ethyl, propyltetradecyl, octadecyl, phenyl, benzyl or tolyl. This may also be a group Y. Preferably, the silane has the formula RSiY3, where R is a pinyl group, and the most preferred silanes are vinyltriethoxysilane, vinyltrimethoxysilane, and combinations thereof. However, it is also possible to use silanes with fewer than two hydrolyzable groups, such as vinylmethyljethoxysilane and pinylphenyldimethoxysilane. The amount of silane used depends on the reaction conditions and the low density polyethylene,
It depends on the type and amount of chlorinated polyethylene and ethylene-vinyl acetate copolymer. The actual amount can vary over a wide range of 0.1 to 2 degrees. However, in general, it is preferable to use low density polyethylene, chlorinated polyethylene, and ethylene monovinyl acetate copolymer in a range of 0.5 to 1 part by weight. As a free radical generator, any compound capable of creating free radical sites in polyethylene under the reaction conditions and having a half-life of less than 6 minutes and preferably less than 1 minute at the reaction temperature may be used. can be used.

The best known and preferred free radical generators for use in the present invention are organic peroxides and besters such as penzoyl peroxide, dichlorobenzoyl peroxide,
Dicumyl peroxide, di-tert-butyl peroxide, 2,5-di(peroxybenzoate) hexin-3
, 1,3bis(tert-butylberoxyisopropyl)benzene, lauroyl peroxide, tert-butylberacetate, 2,5-dimethyl-2,5-di(tert-butylberoxy)hexyne-3,2,5 Mention may be made of -dimethyl-2,5-di(tert-butylberoxy)hexane and tert-butylberbenzoate, azo compounds such as azobisisobutyronitrile and dimethylazodiisoptylate, dicumylperoxide Most preferred.
In any case, the particular free radical generator chosen will depend on the temperature at which the reaction of the polyethylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, and silane is carried out.

Thus, for example, if the reaction is carried out at about 190 DEG -200 DEG C., dicumyl peroxide, which has a half-life of about 1 molten metal at that temperature, is preferred.

If the reaction of the mixture is to be carried out at, say, 15°C, then one should use, for example, penzoyl peroxide, which has a suitable half-life at that temperature. The proportion of free radical generator used will vary depending on the nature of the polyethylene and the degree of modification desired of the polyethylene. Although sufficient free radical generator should be used to effect the desired degree of modification, the proportion of free radical generator should not be such that crosslinking, which is common for polyethylene, is the predominant reaction mechanism. For this reason, it is undesirable to use more than about 0.75 weight percent free radical generator based on the weight of the polyethylene. Small amounts of free radical generators, such as 0.01%, can be used to create some crosslinking potential in the polyethylene, but for most applications, 0.01% by weight of the polyethylene can be used. 05
It is preferred to use up to 0.2% by weight.

A wide variety of materials are known to function as silanol condensation catalysts, and any of these materials can be used in the present invention. Such substances include, for example, carboxylic acids such as dibutyltin dilaurate, stannous acetate, stannous octoate (stannous caprylate); lead naphthenate, zinc caprylate, iron 2-ethylhexanoate, cobalt naphthenate. Organometallic compounds such as salts, titanate esters and chelates, such as titanate tetraptyl ester, titanate tetranonyl ester and bis(acetylacetonitrile) di-sop. Included are pyrutitanate, organic bases such as ethylamine, hexylamine, dibutylamine and pyridine, acids such as inorganic acids and fatty acids. Suitable catalysts are organotin compounds such as dibutyltin dilaurate, diptyltin diacetate and dibutyltin dioctate. In the process of the present invention, polyethylene and silane are reacted at a temperature of 14 psi or higher and lower than the decomposition temperature of polyethylene.
Any suitable apparatus can be used for this reaction as long as it provides sufficient dispersion of the additives and a sufficient temperature for the bran mixture.

For example, the reaction can be carried out using a single or twin screw extruder, a co-kneader, a Banbury mixer, or a roll mill.

The polyethylene, silane, and free radical agent may be mixed and dispersed by any method.

For example, a tumbler can be used to mix and disperse the silane and free radical generator into the polyethylene. The crosslinking reaction of the resin composition produced in step 2 of the process of the invention is accomplished by contacting the resin composition with water in the presence of a silanol condensation catalyst, usually after the product of step 2 has been shaped by extrusion.

Moisture present in the atmosphere can also cause the crosslinking reaction to proceed, but increasing the speed of the crosslinking reaction can be achieved by immersing the product in hot and humid conditions or by submerging it in flooded water. The polyethylene resin composition according to the present invention is not only comparable to those obtained by conventional methods, namely, organic peroxide crosslinking method, but also superior to conventional low density polyethylene in the same manner as ordinary polyethylene due to the unique crosslinking method. It is possible to add the flame retardancy and tracking resistance of chlorinated polyethylene to the processability, and the flexibility of ethylene-vinyl acetate copolymer. It can be used advantageously in any direction.

Next, the present invention will be explained with reference to Examples.

Example 1 ■ 0.15 parts by weight of dicumyl peroxide and 2 parts by weight of pinyltrimethoxysilane per 10 parts by weight of low-density polyethylene (melting index 1.2/1 barb and nominal density 0.924 ta'iso) granules. 0 parts by weight were mixed in a mixer until the granules were completely coated with the silane.

Next, this mixture was extruded under the following conditions using a 65-side presser with a cylinder section whose temperature setting was divided into three regions to obtain a product A. Cylinder supply section 1
2 pi○ compression section 150℃ measuring section
18pi○ Screw rotation speed 3q double turn/min discharge base
30k9/hour■ Furthermore, using the same extruder, 0.12 parts of dicumyl peroxide and 3 parts of vinyltrimethoxysilane were added to 100 parts by weight of chlorinated polyethylene with a chlorine content of 30% and a nominal density of 1.140 parts per hour. Parts by weight were mixed using the mixer, and a mixture was extruded using the 65-side extruder to produce an extruded product B.

The conditions are shown below. cylinder supply section
12 pi○ compression part 14 pi○ measuring part
160℃ Screw rotation speed 3 turns per minute Discharge nose
40 k9/hour ■ Ethylene-vinyl acetate copolymer (melting index 2 min/10 min and vinyl acetate content 20%, nominal density 0.950 min/base) 100 parts by weight of granules, dicumyl peroxide 0. 2.0 parts by weight of vinyltrimethoxysilane and 2.0 parts by weight of vinyltrimethoxysilane were mixed together using the mixer, and the mixture was extruded using the extruder to obtain an extruded product C.

The conditions were set as below. Cylinder supply section
12pi○ Compression part 15pi0 Measuring part 17bi○ Screw IJ rotation speed 3q unit turn/min discharge shot
32k9/hour ■ 1 part by weight of dibutyltin dilaurate was added to 100 parts by weight of low-density polyethylene (same grade as in item ■) to produce product ○ using the 65-leg extruder.

■ The above products A, B, C, and ○ are uniformly blended using a mixer in a ratio of 5 parts by weight of products A4, 5 parts by weight of B4, 5 parts by weight of CI, and 5 parts by weight of D, and a 5-side extruder is used. then 1
．． A fin wire E was made by covering a core wire with a diameter of 2 capes with cross-linked polyethylene and polyvinyl chloride as an outer layer of an electric wire with a diameter of 4.0.

The resulting outer layer coating was free of insoluble gel and had a melting index of 0.3 min/min. ■ The products A, B, C
, D is the weight part of A5, B35 weight part, CI ■ weight part and D
The mixture was uniformly blended using a mixer at a ratio of 5 parts by weight, and coated on a core wire with a shelf diameter of 1.2 using a 5-part extruder to produce a fin wire F with a finished diameter of 2.5 skin.

This coating does not contain any insoluble gel and has a melting index of 0.5 /
It was 1q minutes. Next, these two types of electric wires 8 and F were crosslinked by treating them with boiling water for 2 hours. The immovable gel of this coating was 57% for electric wire E and 61% for electric wire F after being immersed in xylene at 120°C. When these electric wires were examined for flame retardancy according to JISC-3005, the following results were obtained.

Example 2 ■ Low-density polyethylene (melting index 2.0 min/10 min and nominal density 0.920 ta'min) 0.00% dicumyl peroxide per 10 parts by weight of granules. 2 parts by weight of vinyltriethoxysilane were mixed together in a mixer and extruded using a 50 mm extruder to obtain an extruded product G.

The five-arm extruder used has a cylinder temperature divided into three zones. Various conditions are shown below. Cylinder donation stand part 12 pi○ compression part
145℃ Measuring part 17 pi○ Screw L/○: 24 Screw compression ratio: 35 Screw rotation speed: 4 kalpa counter rotation/min Discharge base: 15
k9/hour ■ Chlorinated polyethylene (chlorine content 35%
A mixture of 0.1 parts by weight of dicumyl peroxide and 2.5 parts by weight of vinyltrimethoxysilane were mixed in the mixer with respect to 10 parts by weight of 1.20 parts by weight (nominal density: 1.20 mm/ground). An extruded product was obtained in the extruder.

The extrusion conditions are shown below and the cylinder supply section
】2 pi○ compression part 14 pi○ measuring part
160℃ Screw L/D: 24 Screw compression ratio: 30 Screw rotation speed: 40 Side rotation/min Discharge base: 12
[9/hour■ Low-density polyethylene (same quality as ■)
Product J is prepared by adding 1 part by weight of dibutyltin dilaurate to 100 parts by weight in a five-barrel extruder.

■ 35 parts by weight of the product G, J, and J
The mixture was uniformly mixed using a mixer at a ratio of parts by weight of fly's pupil and J5. Using a 5-board extruder, a 1.2-board core wire was coated to produce an electric wire K with a finished diameter of 2.5-board diameter.

The resulting wire coating did not contain any degrading gel and had a melting index of 0.5/10 minutes. Next, soak this wire in boiling water for 2 minutes.
The insoluble gel of the coating is cross-linked by treatment at 120°C xylene 2. It was 56% after q-life immersion. When these flea wires were examined for flame retardancy according to JISC-3005, the following results were obtained.

Strategy Department (Customer) Posting of amendment pursuant to the provisions of Article 64 of the Patent Law (Showa et al.
, published patent number et al. 1975 patent application No. 113704
No. 96, Patent Publication 3(3)-5 issued on January 25, 1986
(published in No. 446) has been amended pursuant to the provisions of Article 64 of the Patent Law, so it is published as follows.

Patent No. 1339652 lnt. C.I. 4 Identification symbol Internal office reference number C0
8L 51/06 6681-4JI0
2 6681-4JI03 6681-4
J Note 1 The "Claims" section was changed to "1. At 140°C, in the presence of a free radical generator whose half-life at the reaction temperature is 6 minutes or less (1) to a density of 0.915 to 0.940 g/ Low density polyethylene having a density of 1.100 to 1.750 g and a chlorine content of 10 to 80% are reacted with 100 parts by weight of the product of the silane shown below. 200 parts by weight of the product 50 reacted with the silane shown in (3) a density of 0.920~
A resin composition containing 5 to 100 parts by weight of a product obtained by reacting an ethylene-pinyl acetate copolymer with a pinyl acetate content of 5 to 45% with the silane shown below at a rate of 0,980 g/m, A polyethylene resin composition that is crosslinked when exposed to water in the presence of a catalyst.

General formula RRSiY2 (in this formula, R is an olefinically unsaturated -valent hydrocarbon group or a hydrocarbonoxy group, Y is a hydrolyzable organic group, and y is the group R or the group Y) Silane represented by.

” he corrected. 2 Column 4, lines 4-9 “Also...
desirable.

Claims (1)

[Claims] 1. At 140°C in the presence of a free radical generator whose half-life at the reaction temperature is 6 minutes or less (1) Density 0.9
100 parts by weight of a product obtained by reacting low density polyethylene with a density of 15 to 0.940 g/cm^3 with the silane shown below (2) Density of 1.100 to 1.750 g/cm^
3 and a chlorinated polyethylene with a chlorine content of 10 to 80% is reacted with the silane shown below.
0 parts by weight, and (3) density 0.920 to 0.980 g
/cm^3 and a vinyl acetate content of 5 to 45%. A resin composition containing 0 to 100 parts by weight of a product obtained by reacting an ethylene-vinyl acetate copolymer with a silane shown below, comprising: A polyethylene resin composition that is crosslinked when exposed to water in the presence of a silanol condensation catalyst. General formula RR'SiY_2 (in this formula, R is an olefinically unsaturated monovalent hydrocarbon or hydrocarbonoxy group, Y is a hydrolyzable organic group, and R' is a group R
or Y).