JPS6354292B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to a method for crosslinking chlorinated polyethylene compositions. The silane water crosslinking method recently developed by Dow Corning (Zhu) has the characteristic of being able to perform low-temperature and pressureless crosslinking, unlike conventional chemical crosslinking based on reactions with peroxides, amines, etc., and its industrial value is There are some very large ones. Here, we will explain _the silane water crosslinking method applied to chlorinated polyethylene. is an oxy group, Y is a hydrolyzable organic group, and R' is a group R or a group Y)
In this method, a silane represented by (hereinafter simply referred to as silane) is reacted in the presence of peroxide, and then crosslinked by exposure to moisture in the presence of a silanol general catalyst. however,
When silanol condensation catalyst is added to the product obtained by reacting silane with chlorinated polyethylene in the presence of peroxide according to the steam method and extrusion molded using an extruder, foaming occurs on the cross section of the molded product. A decrease was found. This is a phenomenon unique to chlorinated polyethylene that is not observed in ethylene copolymers such as polyethylene, and is extremely problematic in practice. The present invention was made in view of the above situation, and it is an object of the present invention to provide a method for crosslinking a chlorinated polyethylene composition suitable for a silane water crosslinking method with excellent extrusion moldability. [Summary of the Invention] The method for crosslinking a chlorinated polyethylene composition of the present invention comprises adding chloroprene rubber to chlorinated polyethylene,
The ratio of chlorinated polyethylene to chloroprene rubber is
Mixture of 95/5 to 60/40
Per 100 parts by weight, at least one of a lead compound, an epoxy compound, and a magnesium compound is added.
The general formula RR′SiY ₂ is added to the composition by weight or more.
The silane represented by is reacted in the presence of a free radical generator, and the reaction product is crosslinked by exposure to moisture in the presence of a silanol condensation catalyst. In the present invention, in order to prevent the foaming during extrusion molding described above, we have made extensive studies to prevent foaming by adding typical stabilizers for chlorinated polyethylene such as lead-based, tin-based, and epoxy-based stabilizers. However, the ivy could not prevent foaming. However, strangely, when chloroprene rubber is mixed with chlorinated polyethylene within the range specified in the present invention, and at least 1 part by weight of one or more of a lead compound, an epoxy compound, and a magnesium compound is added, silane is It has been discovered that foaming during extrusion molding can be prevented by adding a silanol catalyst to a composition reacted in the presence of peroxide. Then, the amount of chloroprene rubber mixed with chlorinated polyethylene was determined to be 95/
The reason why it is limited to 5 to 60/40 is that below the limit value, foaming cannot be prevented, and above the limit value, the viscosity of the silane-reacted composition increases significantly and extrusion molding cannot be carried out smoothly. This is because it becomes difficult. In addition, the reason why the amount of lead compounds, epoxy compounds, and magnesium compounds added is set to be 1 part by weight or more based on the total of 100 parts by weight of chlorinated polyethylene and chloroprene rubber is that if the amount is less than 1 part by weight, the chlorinated polyethylene This is because foaming during extrusion cannot be prevented even if chloroprene rubber is mixed into the material. Incidentally, when adding a lead compound, an epoxy compound, and a magnesium compound, a plurality of these compounds may be mixed together, and in that case, the total amount of those added must be 1 part by weight or more. To explain the present invention in more detail, the chlorinated polyethylene has a chlorine content (hereinafter referred to as chlorine amount) of 5 to 50% by weight, and among these, the chlorine content is 5% to 50% by weight.
30 to 40% by weight is desirable. The chloroprene rubber used may be of the G type, which uses sulfur-modified rethiuram disulfide as a stabilizer, or the non-sulfur-modified W type, which does not contain them, but the W type is preferable from the viewpoint of stability of the raw rubber. In addition, lead compounds used in the present invention include fatty acid lead such as lead stearate, inorganic acid lead salts such as tribasic sulfur lead, and dibasic lead zinc oxide, and lead oxides such as lead monoxide. . In addition, examples of epoxy compounds include epoxidized soybean oil and bisphenol A diglycidyl ether, and examples of magnesium compounds include magnesium oxide or the chemical formula Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ 3.5H ₂ O. These include hydrotalsact compounds. These may be used alone or in combination of two or more. As mentioned above, the total amount added must be 1 part by weight or more, and although no upper limit is set, it is preferably 50 parts by weight or less from the viewpoint of mechanical properties and processability. In the general formula of the silane used in the process of the invention, R represents a monovalent olefinically unsaturated radical consisting of carbon, hydrogen and optionally oxygen.
Examples of such radicals are vinyl, allyl, butenyl, cyclohexenyl, cyclopentadienyl, cyclohexadienyl, _CH2 =C( _CH3 )
COO(CH ₂ ) ₃ ―, CH ₂ =C(CH ₃ )COOCH ₂ CH ₂ O
(CH ₂ ) ₃ - and and vinyl radicals are preferred. The Y substituent is an alkoxy or alkoxyalkoxy radical having up to 6 carbon atoms, such as methoxy,
Ethoxy and butoxy radicals and acyloxy radicals with up to 6 carbon atoms, such as formyloxy, acetoxy or propionoxy radicals, and oxime radicals with up to 14 carbon atoms, such as -ON=C(CH ₃ ) ₂ - ,-ON=
selected from CCH ₂ C ₂ H ₅ and -ON=C(C ₆ H ₅ ) ₃ . The R' radical can represent a monovalent hydrocarbon radical free of aliphatic unsaturation, such as methyl, ethyl, propyl, tetradecyl, octadecyl, phenyl, benzyl or tolyl. The R' group can also be represented by an R group or a Y group. Preferably the silane has the formula RSiy ₃ and contains three hydrolyzable organic groups; the most preferred silanes would be vinyltriethoxysilane and vinyltrimethoxysilane. However, silanes with only two hydrolyzable groups, such as vinylmethyldiethoxysilane and vinylphenyldimethoxysilane, are also effective. The proportions of silane used will depend in part on the reaction conditions and in part on the degree of modification desired in the chlorinated polyethylene. The actual proportions can vary widely, for example from 0.1 to 20% by weight, based on 100 parts by weight of chlorinated polyethylene or both chlorinated polyethylene and chloroprene rubber. But generally 0.5
It is preferred to use from 5 parts by weight. The free radical-generating compound may be any compound that can generate free radical sites in chlorinated polyethylene under the above reaction conditions and has a half-life of 6 minutes or less, preferably 1 minute or less at the above reaction temperature. compounds can be used. The best known and preferred radical generating compounds for use in the present invention are organic peroxides and peresters such as benzoyl peroxide, dichlobenzoyl peroxide,
Dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoate) hexyne-3,1,3-bis(t-butylperoxyisopropyl)benzene,
lauroyl peroxide, tertiary butyl peracetate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2,5-dimethyl-2.
5-di(t-butylperoxy)hexane and tert-butyl perbenzoate, and azo compounds such as azobis-isobutyronitrile and dimethylazodiisoptylate, with dicumyl peroxide being most preferred. In either example, the free radical generator used depends on the temperature at which the reaction of the polyolefin and silane is to be carried out. The free radical generator should also be used in an amount sufficient to provide the desired degree of modification to the polyolefin. The proportion should not be so high that decomposition of the polyolefin occurs or that crosslinking by free radicals becomes the dominant mechanism. Normally 0.01~20
Used within parts by weight. There is a wide range of materials that can be used as silanol condensation catalysts. Such substances include, for example, dibutyltin dilaurate, stannous acetate, stannous cabrylate, lead naphthenate, zinc cabrylate,
Metal salts of carboxylic acids such as iron 2-ethylcabroate and cobalt naphthenate, organometallic compounds such as esters and chelates of titanium, such as tetrabutyl titanate, tetranonyl titanate and bis(acetylacetonyl)-di-isobro organic bases such as pyrutitanate, ethylamine, hexylamiso, dibutylamine and piveridine,
and acids such as mineral acids and fatty acids. Preferred catalysts are organotin compounds such as dibutyltin dilaurate, dibutyltin diacetate and dibutyltin diocate. The silanol condensation catalyst can be mixed before, during or after the reaction of the chlorinated polyethylene and the silane. [Examples] The present invention will be explained in more detail below using Examples, but it goes without saying that the present invention is not to be interpreted as being limited by such explanations.

【table】

〔Effect of the invention〕

As described above, the method for crosslinking a chlorinated polyethylene composition of the present invention has the advantage that it has excellent extrusion moldability without causing foaming and can be applied to a silane water crosslinking method.

Claims (1)

[Claims] 1 Chloroprene rubber on chlorinated polyethylene,
The ratio of chlorinated polyethylene to chloroprene rubber is
Mixture of 95/5 to 60/40
Per 100 parts by weight, at least one of a lead compound, an epoxy compound, and a magnesium compound is added.
The general formula RR′SiY ₂ is added to the composition by weight or more.
(wherein R is an olefinically unsaturated monovalent hydrocarbon or hydrocarbonoxy group, Y is a hydrolyzable organic group, and R' is a group R or a group Y) is reacted in the presence of a free radical generator, and the reaction product is crosslinked by exposing it to moisture in the presence of a silanol condensation catalyst.