JPS6310734B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber composition, and more specifically to a novel rubber composition comprising a specific ethylene/α-olefin/polyene copolymer rubber and a specific silane compound. A silane compound represented by the general formula () (hereinafter sometimes simply referred to as a silane compound), RR′SiY ₂ () (in the formula, R is bonded to a silicon atom through a silicon-carbon bond and contains a carbon atom and hydrogen a monovalent olefinically unsaturated group consisting of an atom or, in some cases, an oxygen atom, Y is a hydrolyzable organic group, and R′ is a monovalent olefinically unsaturated group that does not contain an olefinically unsaturated group. a hydrocarbon group or the same group as Y) A reactant obtained by heating and reacting an ethylene/propylene/polyene copolymer rubber with an organic peroxide is catalytically crosslinked with water in the presence of a silanol condensation catalyst. The method is publicly known (Tokukai Sho 52-
9054, JP-A-52-33989, and each specification). The above-mentioned crosslinking method has the advantage that expensive crosslinking equipment is not required and molded products with complicated shapes can be easily produced compared to radiation crosslinking methods, peroxide crosslinking methods, and the like. On the other hand, the heating reaction step carried out prior to crosslinking with water is easily carried out using an extruder and is the most preferred industrial method, but ethylene-propylene-polyene copolymer rubber is difficult to pelletize. Therefore, there was a problem in that the benefits of the heating reaction process using an extruder were not fully utilized. Furthermore, when molding the heated reaction product, ethylene-propylene-polyene copolymer rubber has problems in processing, such as poor extrusion processability. Thus, an object of the present invention is to provide a composition free from the above-mentioned drawbacks, and furthermore, the crosslinked product obtained by applying the above-mentioned crosslinking method to the composition is different from the ethylene, propylene, or ethylene propylene obtained by the conventional method. The object of the present invention is to provide a composition that also has the advantages of crosslinked polyene copolymer rubber, and in addition,
It is an object of the present invention to provide a composition that provides a crosslinked product having superior strength characteristics than a crosslinked product of propylene/polyene copolymer rubber. That is, according to the present invention, the molar ratio of ethylene to α-olefin having 4 or more carbon atoms is about 80/20 to
About 95/5 ethylene/α-olefin/polyene copolymer rubber and the general formula () RR′SiY ₂ () (wherein R is bonded to a silicon atom through a silicon-carbon bond, and a carbon atom and a hydrogen atom, In some cases, in addition to these, a monovalent olefinically unsaturated group composed of an oxygen atom, Y is a hydrolyzable organic group, and R' is a monovalent olefinically unsaturated group containing no olefinically unsaturated group. a hydrocarbon group or the same group as Y) and a silane compound represented by the following is provided. The α-olefin component of the ethylene/α-olefin/polyene copolymer rubber used in the present invention is an α-olefin having 4 or more carbon atoms, preferably 4 to 10 carbon atoms, and specifically, 1-butene, 1-pentene. , 4-methyl-1-pentene, 1-hexene,
An example is 1-decene, preferably 1-butene. If propylene is used as the α-olefin, the object of the present invention cannot be achieved as described above. The molar ratio of ethylene and the above α-olefin (ethylene/α-olefin) is about 80/20 to about 95/5,
Preferably, the molar ratio is about 93/7 to about 87/13, and if the molar ratio exceeds about 95/5 and the ethylene component is large, the rubber composition quality such as the flexibility of the crosslinked product will be impaired, and if the molar ratio is less than about 80/20, the ethylene component When the amount of rubber is small, it is difficult to pelletize the rubber, resulting in poor workability in the heating reaction step described below and low strength of the obtained crosslinked product. The polyene components of the copolymer rubber of the present invention include 1,4-hexadiene, 1,6-octadiene,
2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-
Chain non-conjugated dienes such as octadiene, cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5
-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2
-Norbornene, cyclic non-conjugated dienes such as 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl -2,2-
Typical examples include trienes such as norbornadiene, 1,3,7-octatriene, and 1,4,9-decatriene, particularly 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, etc. is preferred. The content of these polyene components is preferably about 4 or more, particularly about 4
~50 is preferred. If the polyene component is too small, the moldability of the heated reaction product described below tends to be poor, and if the polyene component is too large, the heat resistance tends to be poor. The intrinsic viscosity [η], which is a guideline for the molecular weight of the copolymer rubber of the present invention, is measured in a delican solvent (135°C) and is usually about 0.6 to about 6.0 dl/g, preferably about 0.6 to about 6.0 dl/g.
It is about 1.5 dl/g. If this value is too small, less than about 0.6 dl/g, the strength of the crosslinked product is insufficient, and about 6.0 dl/g
If it exceeds dl/g, there will be a drawback that the moldability of the heated reaction product will be poor. The silane compound used in the present invention is represented by the formula (), where R is a monovalent olefinic compound composed of carbon, hydrogen, and optionally an oxygen atom in addition to these. It is an unsaturated group. Such groups include vinyl group, butenyl group, allyl group, cyclohexenyl group, cyclopentadienyl group, cyclohexadienyl group, CH ₂ =
C( _CH3 )COO( _CH2 ) _3- , _CH2 =C( _CH3 )
COOCH ₂ CH ₂ O(CH ₂ ) ₃ - and Among these, a vinyl group is preferred. Y is a hydrolyzable organic group, specifically an alkoxy group such as a methoxy group, an ethoxy group, a butoxy group, an acyloxy group such as a formyloxy group, an acetoxy group, a propionyloxy group; -ON=C(CH ₃ ) ₂ , -ON=C(CH ₃ )C ₂ H ₅ ,
-Oxime group such as ON=C(C ₂ H ₅ ) ₂ ;
Examples include alkylamino groups or arylamino groups such as NHCH ₃ , -NHC ₂ H ₅ and -NH(C ₆ H ₅ ). Y bonds with two or three silane atoms,
These may be different or may be the same. R' is a monovalent hydrocarbon group containing no olefinic double bond or is the same as Y. Examples of the monovalent hydrocarbon group include a methyl group, an ethylpropyl group, a tetradecyl group, an octadecyl group, a phenyl group, a benzyl group, and a tolyl group. or
R' may also be Y. Among such silane compounds, those having a structure of CH ₂ ═CH—SiY ₃ are preferred, and the most preferred examples include vinyltriethoxysilane, vinyltrimethoxysilane, and combinations thereof. Such a silane compound can be used as the copolymer rubber of the present invention.
It is used in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 8 parts by weight, per 100 parts by weight. The following method may be employed to obtain a crosslinked product from the composition of the present invention. That is, the copolymer rubber and the silane compound are first subjected to a step of kneading and heating reaction in the presence of a radical generator, and then subjected to a step of crosslinking in the presence of water. As the radical generator used in the heating reaction step, organic peroxides are preferably used, and examples of such organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di(tert-butyl peroxy). Hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3,1,3-bis(tert-butylperoxy)
butylperoxyisopropyl)benzene, 1,
1-bis(tert-butylperoxy)-3,3,5
-trimethylcyclohexane, n-butyl-4,
4-bis(tert-butylperoxy)valerate,
Benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate,
Tertiary butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tertiary butyl cumyl peroxide, α, α
-Dimethylbenzyl (α,α-dimethyl-m-methylbenzyl) peroxide, α,α-dimethylbenzyl (α,α-dimethyl-p-methylbenzyl) peroxide, α,α-dimethylbenzyl (α,α-dimethyl- m-ethylbenzyl) peroxide, α,α-dimethylbenzyl (α,α-
dimethyl-p-ethylbenzyl) peroxide,
α,α-dimethylbenzyl (α,α-dimethyl-
m-isopropylbenzyl) peroxide, α,
α-dimethylbenzyl (α,α-dimethyl-p-
Examples include isopropylbenzyl) peroxide and mixtures thereof. These radical generators are generally used in an amount of about 0.01 to about 1.5 parts by weight, preferably about 0.01 to about 1 part by weight, per 100 parts by weight of the copolymer rubber. Although the heating reaction step can be carried out in batches using a Banbury mixer roll mixer or the like, it is industrially preferred to carry it out continuously using an extruder. and about 140 to approx.
The reaction is carried out at a reaction temperature of 300°C, preferably about 160 to about 220°C, for about 1 to about 30 minutes, preferably about 2 to about 10 minutes. The reaction product thus produced in the heating reaction step is subjected to a crosslinking step in which it is brought into contact with water in the presence of a silanol condensation catalyst. There are two methods for carrying out this crosslinking step, the first of which is a method in which a silanol condensation catalyst is made to exist in advance in the heating reaction step, and the resulting reaction product is brought into contact with water. In this method, the crosslinking reaction proceeds when the reactant comes into contact with water in the air, so the product lacks storage stability. Therefore, when this method is adopted, an extruder is used,
A recommended method is to mold the product into the desired shape following the reaction and then expose it to water. The second method is to conduct the reaction without adding a condensation catalyst in the heating reaction step, add the condensation catalyst to the resulting reaction product, mold the product, and then expose the molded product to water. In this case, the heating reaction product has high storage stability, especially when Y in the silane compound formula () is alkoxy, so the heating reaction product can be stored uncrosslinked for a long period of time and can be distributed in the market. It has the advantage of being able to be placed safely in the process. Examples of silanol condensation catalysts include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, stannous acetate, stannous caprylate,
metal salts of carboxylic acids such as lead naphthenate, zinc caprylate, iron 2-ethylhexanoate, cobalt naphthenate; metal salts of carboxylic acids such as tetrabutyl titanate, tetranonyl titanate, bis(acetylacetonyl)-di-isopropyltitanate; esters, organic bases such as ethylamine, hexylamine, dibutylamine and piperidine, and mineral acids,
Preferred catalysts include dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctate. Such a condensation catalyst is used in an amount of 0.1 part by weight or more, preferably 0.2 to 1.0 part by weight, per 100 parts by weight of the copolymer rubber. Crosslinking of the reaction product produced in the heating reaction step in the presence of a silanol condensation catalyst is completed by contacting it with water. Crosslinking can occur even with moisture present in the air, but immersion in water is preferred, especially at 50°C.
Crosslinking is accomplished by immersion in hot water at temperatures ranging from 1 to 100°C for 1 to 24 hours. The crosslinked product thus obtained has high modulus, creep resistance, and aging resistance even at high temperatures, and is excellent as an electrical insulating material and a pipe hose for transporting high-temperature liquids. In addition, in the present invention, other antioxidants, pigments, flame retardants, softeners, carbon black, inorganic fillers, etc. may be added as necessary. Examples will be specifically described below. Example 1 Molar ratio of ethylene and 1-butene (ethylene/1
1000 parts by weight of ethylene/1-butene/5-ethylidene-2-norbornene copolymer rubber pellets with an iodine value of 87/13, an iodine value of 10, and an intrinsic viscosity [η] of 1.25 dl/g, 1 part by weight of dicumyl peroxide
After thoroughly stirring and mixing 20 parts by weight of vinyltrimethoxysilane with a Henschel mixer,
The mixture was supplied to a mmφ extruder and a heating reaction was carried out continuously. The conditions of the extruder are as follows. Screw full flight type L/D=25 Temperature Cylinder section 160-180℃ Adapter section 200℃ Die section 180℃ Residence time (heating time) 2 minutes Obtained reaction product (graftomer) 100 parts by weight, dibutyltin laurylate 0.2 Weight part, 2-
After 1 part by weight of mercaptoimidazole (antioxidant) was mixed uniformly with an open roll, it was press-molded and left in hot water at 80°C for 24 hours to perform crosslinking. After drying, a crosslinked sheet with a thickness of 2 mm was obtained. . Using this crosslinked sheet, according to JIS K 6301
100% modulus M ₁₀₀ (Kg/cm ² ) in 25℃ atmosphere,
Stress at break TB (Kg/cm ² ), elongation at break EB (%),
Hardness HS (JIS A) was measured. Furthermore, after heat aging the crosslinked sheet for 168 hours in a tube aging tester set at 135℃, TB and EB were measured in the same manner as above to determine the TB retention rate AR.
- TB (%), retention rate of elongation at break AR - EB (%)
was calculated. In addition, ASTM for crosslinked sheets before heat aging
According to D150, the dielectric constant and dielectric loss tangent were measured under the condition of 1MHZ. The results are shown in Table 1. Examples 2 and 3 Example 1 except that the ethylene/1-butene/dicyclopentadiene copolymer rubber shown in Table 1 was used.
I went in the same way. The results are shown in Table 1. Comparative Example 1 In Example 1, the ethylene/propylene/dicyclopentadiene copolymer rubber listed in Table 1 was used as the copolymer rubber, and the copolymer rubber, dicumyl peroxide, and vinyltrimethoxysilane were further kneaded with an open roll. The procedure was the same as in Example 1, except that a ribbon-like sheet was separated out (front roll: 50°C, back roll: 60°C), and the ribbon-like sheet was subjected to a heating reaction using an extruder. The results are shown in Table 1. When ordinary ethylene-propylene-polyene copolymer rubber is used, when the heating reaction is carried out in an extruder as in this example, it is necessary to perform kneading with rolls and dispense the ribbon-like sheets in advance. Comparative Example 2 This example uses a special ethylene-propylene-dicyclopentadiene copolymer rubber that has a relatively large number of ethylene units, and unlike Comparative Example 1, no work with rolls is required; This is an example of poor physical properties. That is, the same procedure as in Example 1 was carried out except that the copolymer rubber listed in Table 1 was used as the copolymer rubber. From the above examples and comparative examples, it can be seen that the crosslinked products made from the compositions of the present invention sufficiently maintain the performance required for insulating layers of electric wires, flexible hoses, hot water pipes, etc. 【table】

Claims (1)

[Claims] 1. Ethylene α in which the molar ratio of ethylene to α-olefin having 4 or more carbon atoms is about 80/20 to about 95/5.
- Olefin-polyene copolymer rubber, with the general formula () RR′SiY ₂ () (wherein R is bonded to a silicon atom through a silicon-carbon bond, and is a carbon atom and a hydrogen atom, in some cases in addition to these. is a monovalent olefinic unsaturated group consisting of an oxygen atom, Y is a hydrolyzable organic group, and R′ is a monovalent hydrocarbon group containing no olefinic unsaturated group or the same as Y. A rubber composition comprising a silane compound represented by: