JPS5855181B2 - rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a rubber composition, particularly a rubber composition that can provide a rubber elastic body with excellent electrical insulation and flame retardancy, and furthermore, provides a rubber composition that can provide a rubber elastic body with excellent electrical insulation and flame retardancy. The present invention relates to a composition capable of imparting good flame retardancy to polyolefin rubber without using.

In general, polyolefin rubbers are relatively flammable and tend to spread fire due to melt dripping at high temperatures.

However, when applied to electrical, vehicle, and other applications, it is necessary to add and blend a large amount of a flame retardant/flame retardant agent in order to impart sufficiently satisfactory flame retardancy.

It is known that the most common and effective means of imparting flame retardancy is to add a halogen compound and antimony oxide together, but in order to obtain the desired flame retardancy, a large amount of flame retardant A sex-imparting agent must be added.

In addition, it is considered to be extremely disadvantageous economically to use expensive halogen compounds or antimony oxide, and when a rubber elastic body containing the above-mentioned flame retardant imparting agent burns, the flame retardant imparts the flame retardant during combustion. There is a problem in that a large amount of toxic and corrosive gases, which are undesirable in terms of environmental hygiene, are generated due to this, which harms public health.

On the other hand, it has been proposed to fill a large amount of aluminum hydroxide or magnesium hydroxide instead of the above-mentioned compounds in order to eliminate the above-mentioned disadvantages or harmful effects, but filling with these compounds alone is not sufficient. It is difficult to obtain good flame retardancy, and when they are added in large amounts, the inherent mechanical properties of polyolefin rubber deteriorate.

In other words, there is a strong desire for a practical and effective means of imparting excellent flame retardancy to polyolefin rubber without using any halogen compounds, but such a means or method has not yet been found. The current situation is that there is no such thing.

The present invention aims to provide a new rubber composition which eliminates the disadvantages and drawbacks of the conventional rubber compositions as described above, which comprises (a) 100 parts by weight of polyolefin synthetic rubber, (
b) Organopolysiloxane 5 to 100 parts by weight, (c) Specific surface area of 50 rn'/j! 2 to 100 parts by weight of the above silica-based fine powder, 2) 0.5 to 20 parts by weight of a nickel compound, and (e) at least one member selected from aluminum, magnesium hydroxide or carbonate, and hydrotalcites.
Seed compound: 0 to 200 parts by weight.

To explain this, the present inventors have discovered that even when the rubber elastic body comes into contact with flame, it does not generate toxic or corrosive gases, and has almost no effect on the various properties inherent to the polyolefin rubber itself. Furthermore, as a result of extensive research into compositions that can economically advantageously impart flame retardancy to polyolefin rubber, we have found that compositions consisting of the components (a) to (e) described above, as well as more detailed This was completed based on experimental confirmation that a composition comprising components (D), (C), and (2) in combination is extremely effective.

In fact, the rubber elastic body obtained from the composition according to the present invention has extremely good flame retardancy, and this elastic body does not emit any toxic gas even if it comes into contact with flame. Furthermore, it has a remarkable effect of being economically superior.

Hereinafter, the rubber composition according to the present invention will be explained in detail.

Various conventionally known polyolefin synthetic rubbers can be used as the main component in the present invention, and specifically, ethylene-propylene copolymer, ethylene-propylene terpolymer, ethylene-acetic acid Vinyl copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, acrylonitrile-butadiene copolymer, imbutylene-isoprene copolymer, etc. In addition, this component (a) is a thermal It may also be a polymer blend composed of a plastic resin such as polyethylene, polypropylene, polybutylene, polypentene, or an ethylene-butene copolymer.

Next, the type of organpolysiloxane used as the (oral) component used in the present invention is not particularly limited, and various types currently known in the field of silicone chemistry can be used, such as the molecular structure of may be linear, branched, or cyclic, and may be oil-like, rubber-like, or resin-like in shape, and there are no limitations on the type of organic group bonded to the silicon atom.

Examples of this organic group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkenyl groups such as vinyl group and allyl group, monovalent hydrocarbon groups such as aryl groups such as phenyl group and tolyl group, or monovalent hydrocarbon groups such as these. A substituted-valent hydrocarbon group in which the hydrogen atom of the group is partially substituted with a halogen atom such as a chlorine atom, an organic group such as an amine group, a hydroxyl group, or a generally well-known hydrolyzable functional group. Examples include alkoxy groups such as methoxy groups and ethoxy groups, acyloxy groups such as acetoxy groups, amide groups, and aminoxy groups.

The organopolysiloxane as component (b) can be synthesized by various conventionally known methods. For example, those having a linear structure are generally cyclic siloxanes having 3 to 5 silicon atoms. can be obtained by ring-opening polymerization in the presence of an acid or alkali catalyst, and the degree of polymerization can be adjusted by adjusting the amount of triorganosilyl groups or water, and there is no restriction on the degree of polymerization, but the purpose of the present invention From the standpoint of achieving this more reliably, the degree of polymerization is 10.
It is desirable to have a relatively high degree of polymerization of 0 or more, preferably 1000 or more.

Those having a branched structure include trimethoxymethylsilane, trimethoxyphenylsilane, methyltrichlorosilane, vinyltrichlorosilane, phenyltrichlorosilane, tri- or tetrafunctional silanes such as sodium silicate, dimethyldimethoxysilane, dimethyldimethoxysilane, 1 or 2 such as chlorosilane or methylvinyldichlorosilane
The functional silane can be optionally co-hydrolyzed, neutralized and polymerized if necessary.

Such branched organopolysiloxanes are obtained as viscous liquids or solids at room temperature, and these have □5i(4)H groups or \-S 1-OR groups (R; organic groups).

/ It is essential that the amount of component (B) used is in the range of 5 to 100 parts by weight per 100 parts by weight of component (A) above, but this is difficult to satisfy if less than 5 parts by weight is used. It is not possible to impart flammability to the rubber elastic body, and on the other hand, if the amount exceeds 100 parts by weight, the mechanical strength of the rubber elastic body obtained will be significantly reduced.

In addition, when considering the balance between flame retardancy and mechanical strength, it is most preferable to use it in a range of 10 to 30 parts by weight.

As the silica-based fine powder that is the component (c), various types of powder that are usually added to silicone rubber as a reinforcing agent may be used as long as the specific surface area (measured by the BET method) is 50 r11'79 or more. These include fumed silica, precipitated silica, silica aerogel, etc.

Among these, fumed silica is particularly suitable from the viewpoint of imparting flame retardance to a rubber elastic body, which is the object of the present invention.

As such humid silica, AerO8il (
Degussa) or Ca b-()-8i
I (manufactured by Cabot) and the like are commercially available products.

Furthermore, in the present invention, as the component (iii), so-called treated fillers, in which silica is partially treated with silicone, can also be used.

The amount of component (c) to be used is necessarily in the range of 2 to 100 parts by weight per 100 parts by weight of component (a).

This is because if the amount used is less than 2 parts by weight, a rubber elastic body with good flame retardancy cannot be obtained, and the amount of component (c) used is less than the required amount, and any filler other than silica-based fine powder can be used. Even if a large amount of the agent is filled and blended, a satisfactory flame retardant effect cannot be obtained.

On the other hand, if it exceeds 100 parts by weight, not only will there be various difficulties in blending and the use of a large amount of process oil, but also the flame retardance and mechanical strength of the resulting rubber elastic body will deteriorate. become.

When using this component (c), quartz powder, celite (trade name manufactured by Johns-Manville), calcium carbonate, clay, mica, carbon black, graphite, and other known fillers other than silica may be used in combination. Good too.

It is also effective to add silanes containing silanol groups, alkoxy groups, etc., and low molecular weight siloxanes, which are usually used in the formulation of silicone rubber. Carbon functional silanes or cohydrolysates thereof may also be used.

The nickel compound, which is the (ii) component, is considered to be the most important component in the present invention, together with the above-mentioned (ii) components.

These nickel compounds include nickel acetate, nickel acetylacetonate, nickel benzoate,
Complexes of acetylacetone such as nickel salicylate, nickel naphthinate, nickel oleate, nickel stearate, nickel octoate, nickel succinate, basic carbonates, oxides such as nickel (It) oxide, nickel (I) oxide, etc. etc. are exemplified.

Among these, carboxylic acid salts are well dispersed in formulations, and a remarkable effect can be obtained with a small amount of use.

This component) is 0 parts per 100 parts by weight of component (A) above.
．． It is essential to use the amount in the range of 5 to 20 parts by weight, but if it is less than 0.5 parts by weight, sufficient flame retardancy can be obtained.On the other hand, even if it is used in excess of 20 parts by weight, it will not be possible to obtain sufficient flame retardancy. This is because the effect does not improve accordingly, and it becomes economically disadvantageous.

41) Components such as aluminum, magnesium hydroxides or carbonates, and hydrotalcites have been known as flame retardant improvers for various organic polymers. Magnesium, magnesium carbonate or hydrotalcites (Mgx-xAlx(OH)2(CO3)x-2・mH
For example, 2O1, where 0.1<x<0.4.0<m1).

As mentioned above, this component (e) is known as a flame retardancy improver for various organic polymers, but if only this component is used, sufficiently satisfactory flame retardance cannot be obtained.

In particular, for polyolefin polymers that do not contain elements such as halogens, it is difficult to impart not only flame retardancy but also self-extinguishing properties, and even if it were possible to impart such properties, the amount added would be significantly large. It is necessary to
It becomes impossible to obtain products with physical properties that can be put to practical use.

The amount of this component (e) used is 200 parts by weight or less, preferably 20 to 70 parts by weight, per 100 parts by weight of the component (a), but this is obtained when the amount used exceeds 200 parts by weight. The rubber elastic body becomes inferior in mechanical strength and becomes impractical, and furthermore, its electrical characteristics are significantly deteriorated.

The rubber composition according to the present invention is prepared by uniformly dispersing and kneading the above-mentioned components (a) to (e) using ordinary rubber equipment such as a Banbury mixer, kneader, or two-roller. can do.

The process can be carried out under heating if necessary, but if the curing catalyst has already been incorporated into the composition or if the curing catalyst is added during the heating and kneading process, the temperature must be lowered below the decomposition temperature before the kneading process is carried out. It is necessary to do the following.

The composition according to the present invention uses an organic peroxide, a sulfur or sulfur compound-based vulcanizing agent, a crosslinking agent (organohydrodiene polysiloxane) and an addition reaction catalyst (addition reaction crosslinking), or It can be cured by irradiation with high energy.

Examples of the organic peroxide include di-α-cumyl peroxide, di-tert-butyl peroxide, 2.5-
Dimethyl-2,5-di(tert-butylperoxy)
Hexane, 2,5-dimethyl-2,5-di(tert-
butylperoxy)hexyne-3, tert-butylcumyl peroxide, and the like.

Sulfur-based vulcanizing agents such as sulfur vulcanization accelerators and dipencum methylenethiuram tetrasulfide can also be used.

The combination in this sulfur compound-based vulcanization is complex, and it is necessary to appropriately select and use the components (a) and (b) depending on the types and blending ratios of the components.

In addition, as the crosslinking agent and addition reaction catalyst when carrying out addition reaction crosslinking, there can be mentioned various things conventionally used in hydrosilation. Various organopolysiloxanes having three or more of these can be used, and Pt, Pd, Rd, or compounds thereof (chloroplatinic acid, alcohol-modified chloroplatinic acid, etc.) can be used as addition reaction catalysts.

When adopting this addition reaction crosslinking, (a) and (
(b) It is necessary that the component has an aliphatic unsaturated bond and does not contain any additives that would poison the Pt catalyst or the like.

In addition, various additives may be added to the composition of the present invention as necessary, as long as they do not impair the purpose of the present invention, and these include reinforcing agents, extenders, pigments, curing accelerators, and anti-aging agents , antioxidants, ultraviolet absorbers, crosslinking agents, mold release agents, processing aids, and the like.

Furthermore, there is no problem in adding and blending halogens, phosphates (or esters), phosphates, antimony oxide, and other well-known flame retardant aids depending on the purpose.

The composition also includes polyethylene, polypropylene,
A heat-shrinkable rubber molded product can also be obtained by blending a resin such as polymethacrylate.

Even when such a flame-resistant resin is blended, the composition of the present invention has excellent flame retardancy.

In general, thermoplastic resins tend to soften and drip when heated, but this kind of unilateral tendency is also prevented.

The composition prepared as described above can be molded into a desired molded product by not only molding with a mold, but also extrusion molding, calendar molding, etc., and can also be diluted with an appropriate organic solvent, etc. It can also be used as a coating after being dispersed.

As explained above, the composition of the present invention does not contain any norogen compound (mixed with antimony oxide) and can impart good flame retardancy to the rubber elastic body, so its usefulness is It is extremely high and can be used in a wide variety of applications, but it is particularly suitable for electrical insulation.

It is also expected to be applied to various uses where generation of halogen gas is undesirable.

Next, examples of the present invention will be given, and all parts in the examples indicate parts by weight.

Further, flame retardancy was evaluated according to the oxygen index method specified in ASTM D 2863.

This was expressed as the volume fraction of oxygen gas in nitrogen gas required to maintain the flame of the sample material.

Therefore, the higher the oxygen index (ONI), the better the flame retardancy.

Example I EPDM (iodine value 10, ENB, ML1+4(
100°C) 45) 80 parts, 20 parts of methyl vinyl silicone raw rubber (vinyl group content 0.2% (based on total organic groups) 1, degree of polymerization 6000), Aerosil-200 (trade name manufactured by Nippon Aerosil Co., Ltd., Huumed Silica) 20 A rubber compound was obtained by uniformly mixing 60 parts of Bisilite H42M (trade name, aluminum hydroxide, manufactured by Showa Light Metal Co., Ltd.) and 0.5 parts of vinyltrimethoxysilane using a pressurized niegu.

To 180.5 parts of this rubber compound, various metal fatty acid salts as shown in Table 1 below were added to 0.5 parts in terms of metal i.
1 part and 3 parts of 40% silicone oil paste of dicumyl peroxide were added.

Subsequently, the sheet was heated and pressed for 15 minutes at 170° C. and 100 kg/weight to obtain a 2 mm thick sheet, and then secondary vulcanization was performed at 150° C. for 2 hours.

The oxygen index of this sheet-like body was examined and the results are shown in Table 1 below.

(Experimental scraps with an asterisk on the right shoulder are books. This is an embodiment according to the invention.

(The same applies hereinafter) From Table 1 above, it can be seen that only nickel compounds have an extremely effective flame retardant imparting effect.

Example 2 EP43 (trade name manufactured by Japan EP Rubber Co., Ltd., EPDM)
(100 -
Nippon Silica Co., Ltd. (trade name, precipitated silica) 3 parts, nickel octoate 2 parts, decabromodiphenyl ether 25
1 part and 12 parts of antimony oxide were uniformly kneaded using two rolls to obtain a compound.

2.7 parts of 40% dicumyl peroxide silicone oil paste was added to 14.2 parts of this compound, and the mixture was molded and secondarily vulcanized under the same conditions as in Example 1 to obtain a sheet-like product.

The oxygen index of this sheet-like body was examined and the results are shown in Table 2 below.

From Table 2 above, it can be seen that methylvinyl silicone raw rubber (polysiloxane) has a remarkable effect on improving flame retardancy and is also effective in preventing dripping.

Example 3 70 parts of EPT-3045 (trade name, manufactured by Mitsui Chemicals, Inc., EPDM Iiodinated 12), 0.0 parts of methylvinylsiloxane unit.
30 parts of polysiloxane consisting of 5 mol % and 99.5 mol % dimethylsiloxane units, N1 psi l V N
3 (trade name manufactured by Nippon Silica Co., Ltd., precipitated silica, specific surface area 230 m''/g) 30 parts, magnesium hydroxide 200 (trade name manufactured by Shinshin Kagaku Co., Ltd.) 80 parts, zinc white 5 parts, stearic acid 1 part, Two rolls were mixed with 5 parts of α,ω-dihydroxymethylphenylpolysiloxane, 15 parts of Sambar 2280 (trade name, process oil manufactured by Nippon Sun Oil Co., Ltd.), 1 part of 2-mercaptobenzimidazole, and 2.7 parts of dicumyl peroxide. A compound was obtained by uniformly mixing.

After adding nickel compounds of the type and amount shown in Table 3 below to this compound, the compound was heated at 170°C for 10 minutes.
The material was heated and pressed under conditions of 0 kg/crib to obtain a sheet-like material with a thickness of 3 mm.

Specific gravity, hardness, elongation, tensile strength, oxygen index, and horizontal burning rate (JISK 691
1) and the results are shown in Table 3 below.

From Table 3 above, the sheet material obtained from the composition containing the nickel compound has excellent flame retardancy and self-extinguishing properties, and the nickel compound has no effect on general mechanical properties. I know you won't give it.

Example 4 Vamac N-123 (E, I, trade name manufactured by DuPont, ethylene-acrylic acid ester copolymer rubber) 4
5 parts, methyl vinyl silicone raw rubber (vinyl group content 0.1 mol%, degree of polymerization 10,000) 20 parts, low density polyethylene resin 35 parts, N, N', m-phenylene dimaleimide 1 part, nickel acetylaceto 3 parts of N1psil VH2 (trade name, manufactured by Nippon Silica Co., Ltd., fine powder silica, specific surface area 230 m/9), and 60 parts of Bisilite H42M (trade name, manufactured by Showa Light Metal Co., Ltd., aluminum hydroxide) were mixed in a pressure kneader. using 120
A compound was obtained by uniformly heating and mixing at 0C for 30 minutes.

To 194 parts of this compound were added 4 parts of 40% silicone oil paste of dicumyl peroxide, 1 part of 2-mercaptobenzimidazole and 2.6-diter.
0.5 part of t-butyl-4-methylphenol was uniformly added and blended using two rolls.

Then, molding and secondary vulcanization were performed under the same conditions as in Example 1 to obtain a sheet-like product with a thickness of 2 mm.

The oxygen index and presence or absence of dripping were examined for this sheet-like body, and the results are summarized in Table 4 below.

For comparison purposes, (1) one with the same composition as above except that nickel acetylacetonate was not used at all (experiment/+6:22), and (11) one that did not use methyl vinyl silicone raw rubber at all. Those with the same composition as above (Experiment 423) and ([11)
Sheet-like materials were prepared in the same manner using the same composition as above (Experiment/1624), except that nickel acetylacetonate and methyl vinyl silicone raw rubber were not used at all, and the oxygen index and presence or absence of dripping were examined for the results. Shown in the same table.

However, in experiments/1623 and 24, Vamac
The amount of N-123 used was 65 parts in each case.

From Table 4 above, it can be seen that the present invention can be well applied to heat-shrinkable rubbers, and excellent flame retardancy can be obtained despite not containing any halogen compounds.

Claims (1)

[Claims] 1 (a) 100 parts by weight of polyolefin synthetic rubber,
(b) Organopolysiloxane 5 to 100 parts by weight, (
c) 2 to 100 parts by weight of silica-based fine powder having a specific surface area of 50 tri'/9 or more, 2) 0.5 to 20 parts by weight of a nickel compound, and (e) hydroxide or carbonate of aluminum or magnesium, and hydrotal. Rubber composition 2 consisting of at least one compound selected from sites 0 to 200 parts by weight The polyolefin synthetic rubber is ethylene-propylene copolymer, ethylene-propylene gentor polymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, The rubber composition according to claim 1, which is an ethylene-ethyl acrylate copolymer, an acrylonitrile-butadiene copolymer, or an inbutylene-isoprene copolymer.The organopolysiloxane is a methylvinylpolysiloxane raw rubber or an organopolysiloxane resin. Rubber composition 4 according to claim 1 or 2, wherein the hydroxide or carbonate of aluminum or magnesium is AA(OH)3, Mg(OH)2 or MgCO
Claim 1, 2 or 3, which is 3.
Rubber Composition 5 According to Claim 1, 2, 3, or 4, the silica-based differential powder is fumed silica or precipitated silica.