JPH0641391A - Insulating composition and its production - Google Patents

Abstract

PURPOSE:To provide an insulating composition consisting of a co-crosslinked product of chlorinated polyethylene and ethylene-ethyl acrylate copolymer and improved in heat resistance without being accompanied with deposition to the surface of an insulator or lowering of mechanical characteristics. CONSTITUTION:The insulating composition is composed of 100 pts.wt. co- crosslinked product of 20-60wt.% chlorinated polyethylene and 80-40wt.% ethylene-acrylate copolymer and 10-100 pts.wt. crosslinked silicone rubber and the former crosslinking is carried out in the presence of a crosslinked silicone rubber after formation of the crosslinked silicone rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating composition and a method for producing the same, and more particularly to an insulating composition comprising a blend co-crosslinked product of chlorinated polyethylene and an ethylene / acrylic acid ester copolymer and a method for producing the same.

[0002]

2. Description of the Related Art Chlorinated polyethylene is useful as a material for sheaths and insulators of cables and the like, and is particularly excellent in flame retardancy. The ethylene / acrylic acid copolymer has excellent toughness at room temperature, flexibility and mechanical properties at low temperature. The material obtained by blending these and co-crosslinking is excellent in flexibility and flame retardancy, and has good electrical characteristics as an insulator.

The blended co-crosslinked product of chlorinated polyethylene and ethylene / acrylic acid copolymer has heat resistance up to about 105 ° C. (continuous use temperature is not defined by general definition). It is widely used as a lead wire for motors and an insulator for electric wires for vehicles placed in a temperature environment of about 100 ° C.

As will be described later, it is required to improve the heat resistance of this type of insulated wire, and as a method therefor, addition of an antioxidant, blending or copolymerization with a heat resistant polymer such as silicone rubber is required. Is being considered.

[0005]

However, the heat resistance at about 105 ° C. of the conventional blended co-crosslinked product of chlorinated polyethylene and ethylene / acrylic acid copolymer has caused the wiring density to decrease with the recent miniaturization of devices. And the allowable temperature of the atmosphere in which the equipment is used are not sufficient, and further improvement in heat resistance is required.

Among the above-mentioned methods which have been studied as methods for further improving heat resistance, the addition of an antioxidant has a limited effect of increasing heat resistance, and when a large amount is added, copolymerization may occur. A so-called bloom phenomenon occurs that is hindered or deposited on the surface of the insulator. On the other hand, mere blending with a heat resistant polymer significantly reduces mechanical properties. Copolymerization with silicone rubber is also being considered,
Good mechanical properties such as tensile strength, elongation and flexibility have not been obtained. Further, the flame retardancy is lowered by the copolymerization.

Therefore, an object of the present invention is to improve the heat resistance of chlorinated polyethylene and ethylene, without deteriorating the mechanical properties and flame retardance and depositing on the surface of the insulator.
It is to realize an insulating composition comprising a co-crosslinked product of an acrylic acid copolymer.

[0008]

According to the present invention, there is no precipitation on the surface of the insulator or deterioration of mechanical properties,
In order to realize an insulating composition composed of a co-crosslinked product of chlorinated polyethylene having improved heat resistance and an ethylene / acrylic acid ester copolymer, the insulating composition comprises 20 to 60% by weight of chlorinated polyethylene and 80 to 60% by weight. 100 parts by weight of a cross-linked copolymer with 40% by weight of an ethylene / acrylic acid ester copolymer, and a cross-linked silicone rubber 10 to 10
0 part by weight, and the former cross-linking was performed in the coexistence of the cross-linked silicone rubber after its formation. A chlorinated polyethylene and an ethylene / acrylic acid ester copolymer each of which has a molecule modified so as not to be co-crosslinked under the first condition in which an addition reaction for forming a crosslinked silicone rubber is carried out Preferably comprises a mixture of a co-crosslinked body co-crosslinked under different second conditions and a crosslinked silicone rubber. Here, the ethylene-acrylic acid ester copolymer includes not only a copolymer of ethylene and an acrylic ester, but also a copolymer of ethylene and an α-methyl acrylate substituted ester, that is, an ester of methacrylic acid. It shall be.

Further, in the method for producing an insulating composition of the present invention, it comprises a co-crosslinked product of chlorinated polyethylene and an ethylene / acrylic acid ester copolymer which has improved heat resistance without deteriorating mechanical properties. In order to realize a method for producing an insulating composition, chlorinated polyethylene (hereinafter referred to as CP
(Abbreviated as E) and ethylene / acrylic acid ester copolymer (hereinafter abbreviated as EAE) molecules are preliminarily deformed to form a crosslinked silicone rubber by an addition reaction. Even under coexistence, they are not co-crosslinked under the first condition where they undergo an addition reaction, and are allowed to be co-crosslinked under the second condition different from this, and these are blended with the above-mentioned first and second components. Then, the latter addition reaction is performed to form a crosslinked silicone rubber, and the modified CPE and EAE are reacted under the second condition (for example, the presence of a catalyst) in the presence of the crosslinked silicone rubber. Then, the co-crosslinked product of CPE and EAE was obtained as a mixture with the crosslinked silicone rubber.

Silane grafting is preferred as the above modification of the CPE and EAE molecules. The specific steps when silane-grafting CPE and EAE are used are as follows. (1) CPE and EAE are each silane-grafted. (2) Silane-grafted CPE and silane-grafted E
AE is abbreviated as a first component and a second component capable of forming a crosslinked silicone rubber by an addition reaction (hereinafter abbreviated as SG1 and SG2, respectively. The first liquid and the second liquid of what is generally called a two-component liquid silicone rubber). The components of the second liquid correspond to this). (3) Silane-grafted CPE and silane-grafted E
In the presence of AE, SG1 and SG2 are crosslinked by an addition reaction to form a silicone rubber. More specifically, silane graft CPE, silane graft EAE, S
Appropriate temperature and pressure are applied to the mixture of the four components of G1 and SG2 to cause the addition reaction of SG1 and SG2.
At an appropriate temperature and pressure, the addition reaction of SG1 and SG2 is carried out, but silane graft CPE and silane graft EA
The temperature and pressure at which the crosslinking reaction of E does not substantially occur correspond to the first condition. (4) Silane-grafted CPE and silane-grafted EAE in the presence of the formed silicone rubber
Are reacted in the presence of water and a catalyst to give CPE and EA
By co-crosslinking E, a co-crosslinked product of CPE and EAE, that is, chlorinated polyethylene and ethylene / acrylic acid ester copolymer is produced as a mixture (blend) with silicone rubber. The reaction conditions at this time are SG
The conditions are different from the above-mentioned first condition for carrying out the addition reaction of 1 with SG2. This condition also includes whether or not a catalyst is present and whether or not water is present. Therefore, if there is a difference in the presence of the catalyst and water, the temperature and pressure may be the same as in the addition reaction of SG1 and SG2.

The ethylene / acrylic acid ester copolymers include copolymers of ethylene and methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, etc., and ethylene and methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc. Copolymers and the like can be used. Molecular weight, molecular weight distribution, sequence of ethylene and comonomer (acrylic acid ester or methacrylic acid ester) in the molecular chain (eg, random, block), tacticity (atactic, syndiotactic,
With respect to isotactic, etc.), any can be used. The molar ratio of ethylene to comonomer is 90: 1.
A range of 0 to 55:45 is preferred.

The chlorine content, molecular weight, molecular weight distribution, presence of crystals, etc. of the chlorinated polyethylene are arbitrary.

CPE (chlorinated polyethylene) and EAE
The ratio of (ethylene / acrylic acid ester copolymer) is C
PE in the range of 20 to 60% by weight and therefore EAE in the range of 80 to 40% by weight is preferred. If the CPE is less than 20% by weight, the flame retardance is insufficient, and if it exceeds 60% by weight, the flexibility is lowered, which is not preferable. The ratio of CPE and EAE contained in the co-crosslinked product of CPE and EAE in the insulating composition may substantially correspond to the ratio of the amounts of the respective silane graft products and the like used for forming the co-crosslinked product.

In the coexistence with a two-component liquid silicone rubber, a chlorinated polyethylene and an ethylene / acrylic acid ester copolymer are prepared so that the crosslinking reaction does not occur when the silicone rubber is crosslinked by an addition reaction. For co-crosslinking, a silane-grafting method in which these components are silane-grafted and the silane-grafted body is subjected to a crosslinking reaction in the presence of a catalyst is suitable. This reaction requires the presence of water (the silanol condensation reaction of the silane graft body with water,
Crosslink). As a silane compound used for silane grafting of each polymer, for example, vinyltrimethoxysilane,
Vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, vinyltriacetoxysilane,
(Γ-methacryloxypropyl) trimethoxysilane,
Can be used. These can be grafted to the polymer with peroxides such as dicumyl peroxide.

In the two-component liquid silicone rubber, the first component generally has a siloxane skeleton such as dimethyl siloxane, methylphenyl siloxane, diphenyl siloxane, etc., and has a hydroxyl group at the terminal or side chain, and the second component. Is composed of a compound having a vinyl group, and is crosslinked by an addition reaction between the first component and the second component. Both components are usually considered to be liquids with similar viscosities, often 1: 1
It is used by mixing at a ratio of. Although the magnitude of the viscosity is determined by the molecular weight, it is adjusted to an appropriate viscosity depending on the purpose. The addition reaction is usually performed in the presence of a catalyst such as platinum, and the catalyst is usually contained in the second component.

The mixing amount of the two-component liquid silicone rubber is
The amount is 10 to 100 parts by weight based on 100 parts by weight of the blended polymer. If it is less than 10 parts by weight, sufficient heat resistance cannot be obtained, and if it exceeds 100 parts by weight, the tear strength is lowered.

In addition to the above-mentioned components, stabilizers, antioxidants, lubricants, flame retardants, fillers, reinforcing agents, colorants and the like can be added to the insulating composition of the present invention.

[0018]

The insulating composition comprising a co-crosslinked product of chlorinated polyethylene (CPE) and ethylene / acrylic acid ester copolymer (EAE) of the present invention is a co-crosslinked copolymer obtained by co-crosslinking CPE and EAE. And a silicone rubber crosslinked by the addition reaction of the first component and the second component of the liquid silicone rubber, and the crosslinking of this silicone rubber is carried out independently of the co-crosslinking of CPE and EAE. The composition of the present invention is not a ternary copolymer of CPE, EAE and silicone rubber, but is clearly a blended polymer of a copolymer of CPE and EAE and a silicone rubber. It has a polymer network structure in which molecular chains penetrate each other. Due to this structure, without deteriorating mechanical properties or precipitation of one component on the surface,
It seems that improvement in heat resistance is achieved.

In the method for producing an insulating composition of the present invention, the first component (SG1) and the second component (SG2) capable of forming a crosslinked silicone rubber by an addition reaction by preliminarily deforming the molecules of CPE and EAE, respectively. Even under the coexistence of, the co-crosslinking does not occur under the first condition in which this addition reaction is carried out, and the co-crosslinking can be performed in the presence of a catalyst under the second condition different from the first condition. Above SG1 and SG2
And the first suitable conditions are applied to allow only the addition reaction between the latter to crosslink the silicone rubber. Therefore, at the cross-linking stage of this silicone rubber, SG1 and S
Crosslinking occurs only between G2, regardless of CPE and EAE, and the modified CPE and EAE do not change as they are. Therefore, the silicone rubber and the modified CPE and EAE do not change.
And a blend is formed.

In the method for producing an insulating composition of the present invention, after the silicone rubber is cross-linked, the CPE and E which are previously deformed are cross-linked.
AE is reacted under a second condition in the presence of a catalyst to give C
Since PE and EAE are co-crosslinked, the resulting composition is not a three-component co-crosslinked product of CPE, EAE and silicone rubber, but a blend of a co-crosslinked copolymer of CPE and EAE and silicone rubber. Probably due to the polymer network structure in which their molecular chains penetrate each other, the heat resistance was improved without deterioration of mechanical properties or precipitation of one component on the surface. It becomes a thing.

Examples will be shown below to further explain the present invention.

[0022]

[Examples 1 to 4] The components shown in Table 1 (the units of numbers are parts by weight) were kneaded with a B type Banbury mixer for about 10 minutes, and then formed into a sheet having a thickness of about 1 mm with a 6 inch roll.
Press for about 10 minutes with a press heated to 80 ° C and press 1
It was formed into a sheet of mm. As a result, the two-component liquid silicone rubber is crosslinked. In Table 1, chlorinated polyethylene a is Eraslen 401A (trade name of Showa Denko KK) grafted with 2% of vinyltrimethoxysilane, and chlorinated polyethylene b is Eraslen 351A (trade name of Showa Denko KK). 2% vinyltrimethoxysilane
The grafted product and the silane-grafted ethylene / ethyl acrylate copolymer are Lexulon A4250 (trade name of Nippon Petrochemical Co., Ltd.), which has an ethyl acrylate content of 2
5 wt%, melt index (temperature 190 ℃) 5.0
The silane-grafted ethylene / methyl methacrylate copolymer is Acryft M1006 (trade name of Sumitomo Chemical Co., Ltd.) having a methyl methacrylate content of 25% by weight,
Melt index (temperature 190 ℃) 1.0, two-component liquid silicone rubber liquid A contains vinyl-terminated dimethylsiloxane and platinum catalyst, viscosity 3100ps
(Temperature 100 ° C), the two-component liquid silicone rubber liquid B is a mixture of vinyl-terminated dimethylsiloxane and hydrogen-terminated dimethylsiloxane with a platinum catalyst added, and has a viscosity of 2600 ps (temperature 100 ° C). The inhibitor is Irganox 1010 (trade name of Ciba-Geigy, Switzerland).

[0023]

Dibutyltin dilaurate was thinly applied to the surface of the silicone rubber-crosslinked sheet, wrapped loosely in an aluminum foil, and placed in a suitable container with water at the bottom.
It was kept at a temperature of 80 ° C. for 24 hours while keeping it out of direct contact with water. As a result, the chlorinated polyethylene and the ethylene / acrylic acid ester copolymer are co-crosslinked.

With respect to the obtained sheet-like sample, heat resistance,
The flame retardancy and mechanical properties were evaluated by the following methods. As the mechanical properties, tensile strength, elongation, flexibility, and tear strength were measured. (1) Heat resistance Using an aging tester according to JIS, sample at a temperature of 170 ° C. with the passage of time, and find the time to reach an elongation rate of 50% from the graph of change in elongation with time. (2) Flame retardance The oxygen index was measured according to JIS K7201. (3) Tensile properties After being left in a thermostatic chamber at a temperature of 20 ° C for 1 day, it was punched with dumbbell No. 3 and the tensile strength and elongation were measured using a Shopper type tensile tester at a tensile speed of 500 mm / min. (4) Flexibility The 100% modulus in the above tensile test was measured.
0.5 kg / mm ² was used as a standard for flexibility, and if less than this, it was considered to be flexible. (5) Tear strength Based on JISK7201, a B-shaped sample was used and measured at a tensile speed of 500 mm / min by the same Shopper type tensile tester as described above.

The evaluation results are shown in Table 2.

[0027] As shown in Table 2, the insulating composition of the present invention has a temperature of 170
Excellent heat resistance and flame retardancy, with heat resistance of 85 hours or more at 85 ° C for 85 hours or more, flame retardancy of 27 or more as indicated by oxygen index, and tensile strength of 1 ．
8 kg / mm ² or more, elongation of 600% or more, 100% modulus of flexibility of 0.41 or less, and tear strength of 40 kg / cm or more, showing excellent mechanical properties.

[0028]

Comparative Examples 1 to 4 For comparison, a mixture having the composition shown in Table 3 was treated in the same manner as in Examples 1 to 4. As can be seen from Table 3, Comparative Example 1 omits the two-component liquid silicone rubber, Comparative Example 2 omits the silane graft body of EAE, and
One using only the silane graft body of PE (the product becomes a co-crosslinked body of chlorinated polyethylene and silicone rubber), Comparative Example 3 omits the silane graft body of CPE, and E
This is a product using only the AE silane graft product (the product is a co-crosslinked product of an ethylene / ethyl acrylate copolymer and silicone rubber). In Comparative Example 4, the weight ratio of the CPE silane graft body to the EAE silane graft body was 75:25, and this ratio was outside the scope of the present invention. Of these, Comparative Example 1 is a conventional insulating composition obtained by co-crosslinking CPE and EAE by a silane graft method.

[0029] The obtained sheet-like sample was evaluated by the same method as in the example. The evaluation results are shown in Table 4.

[0030]

As shown in Table 4, Comparative Example 1, a conventional CPE / EAE containing no crosslinked silicone rubber.
An insulating composition composed of a co-crosslinked material has an elongation time of 50% at a temperature of 170 ° C. in less than 60 hours and is inferior in heat resistance. Comparative Example 2, a composition consisting only of silicone rubber and CPE, has a 100% modulus of more than 0.7,
Poor flexibility. Comparative Example 3, namely silicone rubber and E
The composition consisting only of AE has an oxygen index of 22 or less, which shows self-extinguishing property, and is inferior in flame retardancy. Comparative Example 4, namely CP
The weight ratio of the E silane graft body to the EAE silane graft body was set to 75:25, which is outside the scope of the present invention, and the total amount of the silane graft CPE and the silane graft EAE co-crosslinked body was 100.
A total of 150 parts by weight of two-component liquid silicone rubber
The tear strength of the insulating composition obtained by using 20 parts by weight is 20 kg.
/ Cm, the tensile strength is less than 1.7 kg / mm ² , and the elongation is around 500%, which is inferior in mechanical properties.

The examples and comparative examples presented above demonstrate the excellent properties of the insulating compositions of the present invention.

[0033]

According to the insulating composition of the present invention, it is possible to improve the heat resistance of an insulating composition comprising a chlorinated polyethylene and a co-crosslinked product of ethylene / acrylic acid copolymer, and to improve mechanical properties and difficulty. No reduction in flammability or precipitation on the surface of the insulator.

According to the method for producing an insulating composition of the present invention,
It has superior heat resistance to conventional insulation compositions consisting of co-crosslinked chlorinated polyethylene and ethylene / acrylic acid copolymer, and also has reduced mechanical properties and flame retardancy and deposition on the surface of the insulation. It is possible to obtain an insulating composition without it.

Claims (4)

[Claims] 1. An insulating composition comprising a co-crosslinked product of chlorinated polyethylene and ethylene / acrylic ester copolymer, wherein 100 parts by weight of chlorinated polyethylene and ethylene / acrylic ester copolymer are cross-linked. Copolymer, and 1
The copolymer comprises 0 to 100 parts by weight of a crosslinked silicone rubber, and the copolymer is a copolymer of 20 to 60% by weight of chlorinated polyethylene and 80 to 40% by weight of an ethylene / acrylic ester copolymer. An insulating composition, which is a coalesced product and is crosslinked in the coexistence of the crosslinked silicone rubber after its formation. 2. The first and second components of a two-component liquid silicone rubber, wherein the crosslinked silicone rubber is a first component of a two-component liquid silicone rubber under the first condition that co-crosslinking of chlorinated polyethylene and ethylene / acrylic acid ester copolymer does not occur. Is formed by an addition reaction between the chlorinated polyethylene and the ethylene / acrylic acid ester copolymer, the molecules of which have been modified in advance so as not to be co-crosslinked under the first condition. The insulating composition according to claim 1, which is formed by co-crosslinking under a second condition different from the first condition. 3. The chlorinated polyethylene and ethylene / acrylic acid ester copolymer, each of which is preliminarily modified in molecule, is a silane-grafted chlorinated polyethylene and a silane-grafted ethylene / acrylic acid ester copolymer. The insulating composition according to claim 2. 4. A method for producing an insulating composition comprising a co-crosslinked product of chlorinated polyethylene and ethylene / acrylic acid ester copolymer, wherein molecules of chlorinated polyethylene and ethylene / acrylic acid ester copolymer are respectively modified. So that the first component and the second component capable of forming a crosslinked silicone rubber by an addition reaction do not co-crosslink under the first condition under which the addition reaction occurs, but can co-crosslink under a second condition different from this. The mixed chlorinated polyethylene and ethylene / acrylic acid ester copolymer, which are each modified, and the first and second components are mixed, and the first and second components are mixed under the first condition. Cross-linking silicone rubber is formed by carrying out an addition reaction of the modified chlorinated polyethylene and the modified ethylene / acrylic acid ester copolymer. It is reacted in the second condition of said chlorinated polyethylene and ethylene
A method for producing an insulating composition, which comprises producing a co-crosslinked product with an acrylic ester copolymer as a blended polymer with a crosslinked silicone rubber. 4. The molecular modification of the chlorinated polyethylene and the ethylene / acrylic acid ester copolymer is a silane graft of each of the chlorinated polyethylene and the ethylene / acrylic acid ester copolymer, and the first condition is The silane-grafted chlorinated polyethylene and the silane-grafted ethylene / acrylic acid ester copolymer do not contain a catalyst for the reaction, and the second condition is that the catalyst and water are present. A method for producing the insulating composition according to claim 4.