JPS6234323B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a chlorinated polyethylene composition which is flexible and capable of being water-crosslinked with silane in the form of pellets. The silane water cross-linking method recently developed by Dow Corning (USA) has the characteristic of being able to perform low-temperature and pressureless cross-linking, unlike conventional chemical cross-linking based on reactions with peroxides, amines, etc., and its industrial value is particularly high for electrical wires. There are some things that are extremely large in the manufacturing field. To explain the silane water cross-linking method here, the silane represented by the general formula RXSiR' ₂ is reacted with the polymer by the action of an organic peroxide, and then cross-linked by exposing it to water in the presence of a silanol condensation catalyst. This is a method that allows However, R is an olefinically unsaturated monovalent hydrocarbon group or a hydrocarbonoxy group, R' is a hydrolyzable organic group, and X is the group R or the group R'. In carrying out this process, it is necessary to impregnate and add silane and peroxide to the pelletized polymer, which is difficult to add using methods that generate a large amount of heat, such as roll kneading or banbari kneading, due to their high volatility. Due to the nature of the wires and the need to prevent wires from sticking to each other during water cross-linking, it is essential that the polymers do not stick to each other even under a certain degree of temperature and pressure. On the other hand, non-polar and highly crystalline polymers such as polyethylene have no problem, but polymers containing highly polar chlorine in the molecule such as chlorinated polyethylene do not allow pellets to interact with each other unless they are particularly highly crystalline. The current situation is that silane crosslinking cannot be carried out due to sticking. The object of the present invention is to provide a highly flexible chlorinated polyethylene composition that is free from adhesion between pellets when formed into pellets during impregnation with silane and peroxide and no adhesion during water crosslinking, even if the amount of crystals in the entire system is small. Our goal is to provide methods for manufacturing products. In other words, the gist of the present invention is that the apparent crystal content of the entire chlorinated polyethylene system with a crystal content of less than 5% is 5 to 5%.
The reason is that a crystalline ethylene copolymer is blended to a concentration of 20%, and silane crosslinking is performed in the form of pellets. Polyethylene, polyethylene content 60-95%
The ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer has weaker polarity than chlorinated polyethylene and is crystalline, so it does not stick to itself. Even if these are blended, they do not dissolve with the chlorinated polyethylene, so they exist in the system in the form of blocks, and suppress mutual adhesion at the interface when pelletized. The reason why the crystal content of the chlorinated polyethylene used in the present invention is specified to be less than 5% is that if it exceeds 5%, it becomes difficult to impart the desired flexibility. Reduce the amount of crystals in the entire blended polymer system to 5-20%
The reason for this limitation is that below the limited value, it becomes difficult to prevent the pellets from adhering to each other during cross-linking with water, and above the limited value, it becomes impossible to obtain the desired flexibility. Examples of crystalline ethylene-based copolymers include ethylene-vinyl acetate copolymers, ethylene-styrene copolymers, ethylene-ethyl acrylate copolymers, and ethylene-propylene copolymers. 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, allylbudenyl, cyclohexenyl, cyclopentadienyl, cyclohexadienyl, _CH2 =C( _CH3 )COO( _CH2 ) _3- ,
_CH2 = _{C ( CH3} ) _COOCH2CH2O ( _CH2 ) _3- and _CH2 = _C ( _{CH3 ) COOCH2CH2OCH2CHCH3O}
(CH ₂ ) ₃ . Among these, a vinyl group is preferred.
The group R' can be any hydrolysable organic group, such as an alkoxy group such as methoxyethoxy and butoxy, an acyloxy group such as formyloxy, acetoxy, or propionoxy, an oxime group, such as -ON=C( CH ₃ ) ₂ −ON=
_CCH2C2H5 and -ON=C( _{C6H5 ) 2} or substituted amino _groups such as alkynoamino and _arylamino groups such _{as -NHCH3} , _-NHC2H5 and -NH( _{C6H5 )} Any hydrolyzable organic group such as The group X can be a group R or a group R'. Preferably, the silane contains three hydrolyzable organic groups, the most preferred silane being vinyltrimethoxysilane, vinyltriethoxysilane. The amount of silane used depends on the reaction conditions as well as the type of resin used and the type of formulation agents.
The actual amount can vary widely from 0.1 to 20 parts by weight. However, it is generally preferable to use it in a range of 0.5 to 10 parts by weight. As the free radical generator, any compound can be used as long as it can create free radical sites in the polyolefin under the reaction conditions and has a half-life of 6 minutes or less, preferably 1 minute or less at the reaction temperature. good. The most well known and preferred free radical generators for use in the present invention are organic peroxides and peresters such as benzoyl peroxide, dichlorobenzoyl peroxide, diqui, milperoxide, di-1-butyl peroxide, oxide, 2,5-dimethyl-2,5-di(peroxybenzoate) hexyne-3,1,3-bis(1
-butylperoxyisopropyl)benzene, lauroylperoxide, 1-butylperacetate, 2.5-dimethyl-2.5-di(1-butylperoxy)hexyne-3, 2.5-dimethyl-2.5-di(1-butylperoxy) Hexane and 1-butyl perpenzoate, and azo compounds such as azobisisobutyronitrile and dimethylazodiisobutyrate. Among these, diquinyl peroxide and lauroyl peroxide are 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 free radical crosslinking becomes the dominant mechanism. 0.01-2.0 for normal cases
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 caprylate, lead naphthenate, zinc caprylate,
Metal salts of carboxylic acids such as iron 2-ethylcaproate and cobalt naphthenate, organic compounds such as esters and chelates of titanium, such as tetrabutyl titanate, tetranonyl titanate and bis(acetylacetonyl)-di-isopropyl titanate. , organic bases such as ethylamine, hexylamine, dibutylamine and piperidine, and acids such as mineral acids and fatty acids. Preferred catalysts are organotin compounds such as dibutyltin dilaurate, dibutyltin diacetate and dibutyltin dioctoate. Next, examples of the present invention and comparative examples will be explained with reference to Table 1. In Table 1, pellet stickiness was evaluated by kneading the composition excluding silane and peroxide for 15 minutes using a 6-inch roll set at 120-140°C, cutting a 1 mm sheet into 2 mm squares, and placing the pellet in 18 iron containers ( 25 x 25 x 40) to a height of 30 cm, left at 60°C for 24 hours, and after cooling, the adhesion of the pellets to each other was examined. In addition, the tackiness during water crosslinking was evaluated by impregnating the pellets prepared as above with silane and peroxide, head: 180°C, C ₁ : 180°C.
°C, _C2 : 40m/m extruder (L/D
= 22) at a screw speed of 40 revolutions to react the silane. Next, 5% of the catalyst masterbatch shown in Table 2 was added to this using a roll to make a 1 mm sheet (120 mm long x 100 mm wide).
mm), put the two sheets together, apply a load of 1 kg from above, and leave them in saturated steam at 60°C for 24 hours. After cooling, the adhesion between the sheets was examined. In addition, flexibility is measured using hardness as a guideline by stacking six 1mm sheets above and using JIS shore A.
It was evaluated by In addition, as a measure of the degree of crosslinking, the gel fraction value after immersion in xylene at 110°C for 24 hours was also investigated. In Examples 1 to 3, silane crosslinking was carried out by the method of the present invention, and in all of them, there was no adhesion of the pellets or adhesion of the sheet during water crosslinking, and as can be seen from the hardness results, there was sufficient adhesiveness. It can be seen that it has flexibility. Moreover, the gel fraction is also sufficiently high. On the other hand, in Comparative Example 1, chlorinated polyethylene was used alone with a small crystal content of 4%, but the pellets became extremely sticky and difficult to loosen, making it impossible to carry out silane crosslinking. Comparative Example 2 uses chlorinated polyethylene alone, and since it uses a material with a large amount of crystals, there is no adhesion, but the hardness is 92, indicating that it lacks flexibility. In Comparative Example 3, an ethylene copolymer was blended, but since the amount of crystals in the system was below the claimed range of the present invention, the adhesion was too large and silane crosslinking could not be carried out. As explained above, with the production method of the present invention, it is possible to obtain a highly flexible chlorinated polyethylene composition that is free from stickiness when pelletized and water-crosslinked, and is suitable for industrial use. The utility value is extremely large.

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Claims (1)

[Claims] 1 Blend an ethylene copolymer with chlorinated polyethylene with a crystal content of less than 5% so that the apparent crystal content of the entire system is 5 to 20%, form this composition into pellets, and crosslink with silane water. A method for producing a chlorinated polyethylene composition, characterized by: