JPH0119817B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a transparent rubber composition, particularly to a transparent rubber composition that provides a polyolefin-based organic polymer article with excellent transparency and strength, which is useful for medical tubes, flexible lenses, etc. It is something. (Prior Art) In order to make a rubber article based on a polyolefin organic polymer particularly highly transparent, various additives in the rubber composition that provides the rubber article are used to improve the solubility and refractive index of the rubber article as the main component. It is necessary to match or approximate that of the polyolefin-based polymer. Therefore, this rubber composition contains not only carbon black, but also fillers such as clay, zinc white necessary for vulcanization, and Sansen and Samper [Nippon Sen Oil Co., Ltd.], which are essential for improving workability. Polybutene/polybis (trade name, manufactured by NOF Corporation), which is a synthetic oil, is not preferred because it has poor heat resistance, although there is no problem with transparency. do not have. Therefore, the materials that can be used for rubber compositions that provide rubber articles based on transparent polyolefin-based organic polymers are broadly limited, and must have all the characteristics of mechanical strength, heat resistance, weather resistance, roll processability, and vulcanization properties. It was impossible to satisfy. (Structure of the Invention) The present invention relates to a transparent polyolefin-based organic polymer composition that solves the above disadvantages, and which comprises (1) an ethylene-propylene-based organic polymer and/or an ethylene-propylene-diene-based organic polymer 100 parts by weight, (2) 1 to 100 parts by weight of methylphenylpolysiloxane containing at least two unsaturated groups in one molecule and having a refractive index of 1.42 to 1.52 at 25°C (3) Specific surface area 10 to 150 parts by weight of fine silica powder having an area of at least 50 m ² /g. That is, as a result of various studies by the present inventors on methods for obtaining polyolefin rubber articles with good transparency, the refractive index n ²⁵ _D of ethylene-propylene-based and ethylene-propylene-diene-based organic polymers having functional groups was found to be A compound containing methylphenylpolysiloxane with a particle size of 1.42 to 1.52 and fine silica powder with a specific surface area of 50 m ² /g or more has high transparency, excellent vulcanization properties and roll processability, and can be processed using process oil. It was discovered that there was no need for the addition of rubber, and that the rubber articles obtained by curing the rubber had high strength, excellent heat resistance, and weather resistance. It has been confirmed that, despite the addition of siloxane, the staining properties are significantly reduced and that saturated hydrocarbon oils can be added as auxiliaries in the processing of this formulation, The present invention was completed by conducting research on the types and amounts of each of these components. The polyolefin organic polymer as the first component constituting the rubber composition of the present invention is commercially available ethylene-propylene organic polymer (hereinafter abbreviated as EPM), ethylene-propylene-diene organic polymer (hereinafter abbreviated as EPDM). Or a mixture of these may be used, but these should preferably have a propylene content of about 40 to 70% by weight, and common diene monomers include ethylidene norbornene, dicyclopentadiene, and 1,4-hexadiene. be done. Furthermore, since the methylphenylpolysiloxane as the second component constituting this rubber composition is vulcanized together with the polyolefin-based synthetic rubber as the first component, it is co-cured with this polyolefin-based synthetic rubber. It is said that one molecule contains at least two unsaturated groups such as vinyl groups and allyl groups as functional groups for sulfurization, but this means that if the refractive index is 1.42 or less or 1.52 or more, Since the refractive index is different from that of the polyolefin organic polymer, the rubber composition blended with it becomes opaque, so in order not to impair its transparency, a rubber composition with a refractive index of 1.42 to 1.52 at 25°C is used. It needs to be within the range. However, this methylphenyl polysiloxane may be oily, resinous, rubbery, or a mixture of two or more of these, and has the formula (RSiO _1.5 ) _l (R ₂ SiO) _n ( _R3SiO0.5 ) _{o (} SiO)
_k , and this R is an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, a vinyl group,
Alkenyl groups such as allyl groups, aryl groups such as phenyl groups and tolyl groups, cycloalkyl groups such as cyclohexyl groups, or some or all of the hydrogen atoms bonded to carbon atoms of these groups can be replaced with halogen atoms, cyano groups, and mercapto. The same or different unsubstituted or substituted monovalent hydrocarbon groups selected from chloromethyl group, trifluoropropyl group, cyanomethyl group, mercaptomethyl group, etc. substituted with groups, or methoxy group, ethoxy group, propoxy group, etc. Groups selected from alkoxy groups, hydroxyl groups, etc., l, m, n, and k are each independently 0 or an integer. Therefore, this R
is a methyl group or a phenyl group, for example, the formula [(CH ₃ ) ₂ SiO] _n [(C ₆ H ₅ ) ₂ SiO] _n ′, m′/m=
0.17 to 0.30, this organopolysiloxane has the formula

[Formula] (p is an integer of 3 to 5) It can be obtained by cleavage polymerization of a cyclic organopolysiloxane represented by the formula (R ₃ SiO _0.5 ) _o (SiO ₂ ) _k
The organopolysiloxane resin represented by (n, k is an integer of n/k = 0.4 to 2.1) is a trichlorosilane resin such as methyltrichlorosilane, phenyltrichlorosilane, methyltrimethoxysilane, phenyltrimethoxysilane, or vinyltrichlorosilane. functional hydrolyzable organosilane or sodium silicate and optionally added dimethyldichlorosilane,
(Co)hydrolyzed with difunctional hydrolyzable organosilane such as methylvinyldichlorosilane, dimethyldimethoxysilane, or monofunctional hydrolyzable organosilane such as trimethylchlorosilane, and polymerization as necessary after removing the by-produced acid. It can be obtained by letting This organopolysiloxane is the EPM mentioned above,
It works to improve the weather resistance and heat resistance of polyolefin-based organic polymers such as EPDM, but it also works to reduce the viscosity of rubber compounds containing silica, so paraffin-based, It can be sufficiently molded without the addition of naphthenic process oil, and also acts as a processing aid. If the amount of this methylphenylpolysiloxane is less than 1 part by weight per 100 parts by weight of the polyolefin organic polymer as the first component, the effect of the addition will be insufficient, and if it is more than 100 parts by weight, the composition will Since the rubber molded product obtained from the product will be weak in strength, 1~
A range of 100 parts by weight is required, but
The preferred range is 5 to 50 parts by weight. Next, the silica fine powder as the third component constituting this rubber composition is considered to be a reinforcing agent, and from the viewpoint of its reinforcing property and transparency, it should have a specific surface area of at least 50 m ² /g. This includes fumed silica and precipitated silica. The amount of this fine silica powder added is 10 parts by weight per 100 parts by weight of the polyolefin organic polymer as the first component.
If it is less than 150 parts by weight, sufficient reinforcing effect cannot be obtained.
If the amount is more than 1 part by weight, the physical properties of the rubber molded product obtained from this composition will deteriorate, so it is necessary to keep it in the range of 10 to 150 parts by weight. It may also be kneaded together with a wetting agent. The transparent rubber composition of the present invention can be obtained by kneading predetermined amounts of the first to third components described above using a two-roll, kneader, Banbury mixer, etc., and the processability can be improved by lowering the viscosity. Hydrocarbon-based synthetic oil may be added for the purpose of , R is a hydrocarbon group represented by C _o H _2o+1 ,
x, y, p, n are integers and the viscosity at 100℃ is
It is desirable that the methylphenylpolysiloxane be 20 to 200cS, but if the amount of methylphenylpolysiloxane as the second component to the polyolefin organic polymer as the first component is 20% by weight or more, the methylphenylpolysiloxane The addition of siloxane provides sufficient rollability to the composition, so it is not necessary to add it, and therefore it is necessary to add it when the amount of methylphenylpolysiloxane is 5 to 20% by weight, The amount added should be in the range of 1 to 100 parts by weight, since if it exceeds 100 parts by weight, the strength of the rubber molded product obtained from it will be weak. In addition, this rubber composition may contain conventionally known additives, such as heat resistance improvers, ultraviolet absorbers,
Carbon functional silane or the like may be added. Since this product is made into a rubber molded product through a curing reaction accompanied by crosslinking, it is necessary to add a necessary crosslinking agent. Depending on the type of functional group contained in the composition, this curing reaction may include a crosslinking reaction using an organic peroxide, addition reaction crosslinking, sulfur vulcanization, etc. Mil peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di (t-butylperoxy)hexyne, 1,1-bis-t-butylperoxy-
Examples include 3,3,5-trimethylcyclohexane. The rubber composition of the present invention has transparency, roll processability,
It has excellent vulcanization properties, and the rubber molded products obtained by vulcanizing it have greater mechanical strength than molded products obtained from silicone rubber compositions that have the same transparency as the composition of the present invention. , the surface has the advantage of having a low tackiness, low coefficient of friction, and good resistance to contamination. In addition, since this composition does not contain any plasticizers such as DOP and DBP, it provides molded products with superior transparency, flexibility, and rubber elasticity compared to molded products made of vinyl chloride, etc. Molded products are used for medical purposes as packing materials such as tubes or O-rings.
It has the advantage that it can be used in a wide range of food-related fields, as a cover member for input devices for various office electronic devices, as a transparent jacket material for ignition cords, as a flexible lens, and as a weather-resistant tent material. It is. Next, examples of the present invention will be given, and parts in the examples indicate parts by weight. Example 1, Comparative Example 1 70 parts of polyolefin organic polymer EP43 [trade name manufactured by Japan EP Rubber Co., Ltd.] and 79.5 mol% of (CH ₃ ) ₂ SiO units and 20 mol% of (C ₆ H ₅ ) ₂ SiO units ,
(CH ₃ )(CH ₂ =CH) 30 parts of methylphenylpolysiloxane raw rubber with an average weight of 8000 and a refractive index of 1.49 at 25°C, consisting of 0.5 mol% SiO units, and 2
Wrap it around a roll with a specific surface area of 380m ² /
30 parts of silica fine powder Aerosil 380 (trade name, manufactured by Nippon Silica Co., Ltd.) was added and kneaded uniformly to prepare a rubber composition. Next, 1.5 parts of dicumyl peroxide was added to 100 parts of this composition and mixed uniformly.
50×50×1 by heat pressing for 15 minutes under the condition of 100Kg/ ^cm2
Make a test piece of mm and calculate the parallel light transmittance of this test piece.
When measured according to the method of JIS K 6714, it was 96%, but for comparison, instead of the methylphenyl polysiloxane above, (CH ₃ ) ₂ SiO units 99.5 mol%, (CH ₃ ) ( _CH2 =CH)
25 with an average degree of polymerization of 8000, consisting of 0.5 mol% SiO units.
The parallel light transmittance of a test piece made from a composition obtained using 30 parts of dimethylvinylpolysiloxane crude rubber having a refractive index of 1.40 at 0.degree. C. was 5%. Examples 2 to 3, Comparative Example 2 70 parts of polyolefin organic polymer EPT3045 [trade name manufactured by Mitsui Petrochemicals Co., Ltd.], 81.5 mol% of (CH ₃ ) ₂ SiO units, and (C ₆ H ₅ ) ₂ SiO units 18 mol%,
(CH ₃ ) (CH ₂ = CH) The average degree of polymerization is 8000, consisting of 0.5 mol% of SiO units, and the refractive index at 25°C is
1.48 methylphenyl polysiloxane raw rubber
30 parts of the mixture was wound around two rolls, and 30 parts of silica fine powder Aerosil 380 (mentioned above) was added thereto and uniformly kneaded to prepare a rubber composition. Next, 1.5 parts of dicumyl peroxide was added to 100 parts of this rubber composition and mixed uniformly.
℃, 100Kg/ ^cm2 for 15 minutes to a thickness of 2.
mm test pieces and 50 x 50 x 1 mm sheets were made, and the initial physical properties, parallel light transmittance, and weather resistance of these were examined, and the results shown in Table 1 below were obtained. Ultraviolet absorber for objects - Titavin 326 [Ciba Geigy product name] 1.0
For comparison, similar tests were conducted on test pieces made from the above composition without the addition of methylphenylpolysiloxane raw rubber, and the results were as shown in Table 1. Obtained.

【table】

[Table] Examples 4 to 6, Comparative Example 3 60 parts of polyolefin organic polymer EPT3045 (mentioned above), 81.5 mol% of (CH ₃ ) ₂ SiO units,
(C ₆ H ₅ ) ₂ SiO units 18 mol%, (CH ₃ ) (CH ₂ =CH)
Average degree of polymerization consisting of 0.5 mol% SiO unit is 8000
Then, 40 parts of methylphenylpolysiloxane raw rubber with a refractive index of 1.48 at 25°C was wound around two rolls, and quartz powder with a specific surface area of 19 m ² /g was wrapped around this.
Crystallite V×S [trade name manufactured by Ryumori Co., Ltd.] and fine powder silica have specific surface areas of 130, 200, and 380 m ² /
30 parts each of Aerosil 130, 200, and 380 (all trade names manufactured by Nippon Silica Co., Ltd.) were added and kneaded uniformly to make four types of rubber compositions, and then these rubber compositions were mixed. Dicumyl peroxide 1.5 to 100 parts
100Kg/170℃
50 x 50 x 1 mm by heat pressure treatment for 15 minutes under cm ² conditions
When test pieces were prepared and their parallel light transmittance was measured, the results shown in Table ² were obtained. The transmittance was 80% or more, but only 2% had a transmittance of 50 m ² /g or less.

【table】

Claims (1)

[Claims] 1 (1) 100 parts by weight of an ethylene-propylene organic polymer and/or an ethylene-propylene-diene organic polymer (2) containing at least two unsaturated groups in one molecule, at 25°C Methylphenylpolysiloxane with a refractive index ranging from 1.42 to 1.52
1 to 100 parts by weight (3) 10 to 150 parts by weight of fine silica powder having a specific surface area of at least 50 m ² /g. 2. The transparent rubber composition according to claim 1, wherein the silica fine powder has a specific surface area of 100 m ² /g or more. 3. The transparent rubber composition according to claim 1, wherein the silica fine powder is surface-treated with an organopolysiloxane containing trimethylsilyl groups or dimethylsilyl groups.