KR20190140577A - Olefinic thermoplastic silicon elastomer composite and molding article formed from the same - Google Patents

Abstract

Disclosed is an olefin-based thermoplastic silicone elastomer composition manufactured by dynamic crosslinking that improves flowability, elasticity, oil resistance, thermal stability, and mechanical properties, enables low hardness, and additionally reduces costs. The composition, based on 100 parts by weight of silicone rubber, comprises 5 to 200 parts by weight of styrene-based block copolymer resin; and 0.5 to 100 parts by weight of mineral white oil.

Description

Olefinic thermoplastic silicon elastomer composite and molding article formed from the same

The present invention relates to an olefinic thermoplastic silicone elastomer composition, and more particularly, to a technique capable of improving flowability, elasticity, oil resistance, thermal stability, mechanical properties, low hardness, and incidentally reducing costs.

General thermosetting rubber has a disadvantage in that it is not recycled like plastic, so a lot of scrap occurs and the curing time is long, resulting in low productivity.

As a material for solving the problems of rubber, thermoplastic elastomers (TPEs) having improved heat resistance through dynamic vulcanization have been developed.

Dynamically crosslinked thermoplastic elastomers are thermoplastic and elastic polymer blends that have the same mechanical properties as elastomers.However, unlike conventional rubbers, they can be processed and reprocessed like plastics at high temperatures, compared to thermoset rubbers with chemical bonds. It has the great advantage that the scrap can be recycled.

In addition, the thermoplastic elastomer can be manufactured by using a general plastic equipment, and can be manufactured by injection, extrusion, foam molding, etc. because it is relatively easy to process.

Currently commercially available olefinic TPEs that can be prepared by dynamic crosslinking are olefinic thermoplastic vulcanizates (TPVs) made by dynamically crosslinking a mixture of polypropylene (PP) and ethylene propylene rubber (EPR). And olefin-based thermoplastic silicone vulcanizate (TPSiV) made of a mixture of polypropylene and silicone rubber by dynamic crosslinking.

Olefin-based thermoplastic elastomers with ethylene propylene rubbers are dynamically used in the automotive field, but due to problems such as phenolic curatives and crosslinking accelerators, which are mainly used for dynamic crosslinking, they are inadequate for human fitness and odors in TPV. There is a problem in that it is not suitable for expanding to food contact or medical use.

As an alternative to this, olefin thermoplastic silicone elastomer is a high performance thermoplastic elastomer having excellent heat resistance and environmental characteristics, which are characteristic of silicone. Recently, the interest in commercialization is increasing in various fields such as food contact containers or medical supplies as well as in automobiles. There have been limitations in commercialization due to insufficient processing flow and difficulty in low hardness.

As the olefin thermoplastic silicone elastomer, polyethylene, polypropylene, copolymerized olefin resin, etc. may be used as the matrix resin, and high molecular weight polysiloxanes are used as the elastomer domain, and dynamic crosslinking with a crosslinking agent and a catalyst Mainly done.

US Pat. No. 6,013,715 is based on a diorganopolysiloxane such as silicone gum as a crosslinking agent and catalyst for a hydrosilylation reaction when a polyolefin-based thermoplastic resin is used as a matrix resin. The main feature of the configuration is to propose a method for dynamic crosslinking.

The olefin-based thermoplastic silicone elastomer composition prepared by this method exhibits high performance characteristics such as excellent heat resistance, cold resistance, and environmental friendliness based on silicon inherent, while exhibiting similar levels to the existing EPDM / PP based TPV physical properties.

However, in the olefin-based thermoplastic silicone elastomer composition prepared by the conventional method, there is a problem that yellowing of the silicon during dynamic crosslinking of the composition in which the silicone gum ratio is used as high as 50 to 80% in order to lower the hardness, and the high temperature melting during processing of the molded article There is a disadvantage in that the flowability is difficult to make a molding of a complex shape.

In addition, it is not possible to make low hardness compositions having a certain level of flowability and mechanical properties, etc., so that their use is limited only to moldings having a hardness of Shoa 65A or higher.

In addition, when more than 60% of the silicon is used, the relatively expensive silicon effect has brought a constraint that can not be commercially spread to various industries.

In conclusion, we have developed technology to solve the cost, flowability, and low hardness problems of existing olefinic thermoplastic silicone elastomers, and expand commercialization to food contact packing, container lids, hoses, medical supplies, and wire insulation. In addition to improving flowability and low hardness, such applications require additional environmental resistance, compression set and mechanical properties, chemical resistance, and heat resistance at high temperatures.

Accordingly, it is an object of the present invention to provide an olefinic thermoplastic silicone elastomer composition capable of low hardness while improving flowability, elasticity, oil resistance and mechanical properties.

The above object is an olefinic thermoplastic silicone elastomer composition based on an olefinic thermoplastic resin and a silicone rubber and prepared by dynamic crosslinking by a hydrosilylation reaction, wherein the elastomeric composition is based on 100 parts by weight of the silicone rubber. To 200 parts by weight of a styrenic block copolymer resin, and 0.5 to 100 parts by weight of a mineral white oil.

Preferably, the elastomer composition, based on 100 parts by weight of the silicone rubber, 10 to 200 parts by weight of polyolefin resin, 20 parts by weight or less of a compatibilizer, 0.1 to 10 parts by weight of an addition-curable crosslinking agent, and a catalyst having a metal atom of 0.05 to 100 ppm It may include.

Preferably, the styrene block copolymer resin is alone or from a block copolymer of styrene-ethylene / butylene-styrene block copolymer, styrene-ethylene / propylene-styrene block copolymer, styrene-ethylene / ethylene-propylene-styrene. One or more kinds may be mixed.

Preferably, the polyolefin resin may be used alone or in combination of two or more polypropylene, polyethylene, alpha olefin copolymer resin.

Preferably, the compatibilizer may be selected from ethylene-maleic anhydride copolymer, propylene-maleic anhydride copolymer, alpha olefin-maleic anhydride copolymer, maleic anhydride styrene-ethylene-butylene-styrene copolymer.

According to the above constitution, since the elastomer composition can be made low in hardness, it is possible to commercialize it because it is possible to specialize in medical supplies such as airtight containers for food contact, high elastic gaskets, medical supplies such as medical elastic tubes and sealing caps, wire insulation materials and automobile products, etc. It can be applied to various fields.

In addition, the processability and high temperature melt flowability is improved to facilitate the production of complex molded articles, and the thermal stability at the time of manufacturing can be avoided to prevent the use of antioxidants, there is no harmful effect on the human body, such as food contact.

Technical terms used in the present invention are merely used to describe specific embodiments, it should be noted that it is not intended to limit the present invention. In addition, the technical terms used in the present invention should be interpreted as meanings generally understood by those skilled in the art unless the present invention has a special meaning defined in the present invention, and is excessively comprehensive. It should not be interpreted in the sense of or in the sense of being excessively reduced. In addition, when a technical term used in the present invention is an incorrect technical term that does not accurately express the spirit of the present invention, it should be replaced with a technical term that can be properly understood by those skilled in the art. In addition, the general terms used in the present invention should be interpreted as defined in the dictionary or according to the context before and after, and should not be interpreted in an excessively reduced sense.

According to the present invention, a styrenic block copolymer (SBC), a mineral white oil, or the like is contained in a thermoplastic silicone elastomer basic composition formed through dynamic crosslinking by addition reaction with a silicone rubber and a polyolefin-based thermoplastic resin. It was possible to obtain a thermoplastic elastomer composition in which physical properties are improved by adding a low hardness.

The elastomer composition of the present invention, based on 100 parts by weight of silicone base rubber, 10 to 200 parts by weight of polyolefin resin, 5 to 200 parts by weight of styrenic block copolymer resin, 0.5 to 100 parts by weight of mineral white oil, commercialization of 20 parts by weight or less First, 0.1 to 10 parts by weight of an additive crosslinking agent, and a catalyst having a content of 0.05 to 100 ppm of metal atoms.

Hereinafter, the present invention will be described in detail.

As described above, the olefinic thermoplastic silicone elastomer composition of the present invention includes a silicone base rubber, a polyolefin resin, a styrenic block copolymer resin, a mineral white oil, a compatibilizer, an additive crosslinking agent, and a catalyst.

As the silicone base rubber, a siloxane polymer or copolymer having two or more alkenyl fuctional groups is used, and in particular, an alkenyl group having a vinyl group of 0.01 to 1% bonded thereto is mainly used.

Silicone rubber is mainly used in the form of gum (high-molecular weight diorgano polysiloxane), and may be used alone or in combination of liquid diorgano polysiloxane fluid (fluid).

Reinforcing silica may be selectively used in the silicone rubber, and fumed silica, precipitated silica, and the like may be used as the reinforcing silica. Generally, fumed silica is preferable.

The polyolefin resin may be used alone or mixed with polypropylene, polyethylene, or alphaolefin copolymer resin, and the content of at least one polyolefin resin selected from the group consisting of these is 10 to 200 parts by weight based on 100 parts by weight of the silicone rubber. Preferably polypropylene resin is preferable.

The polypropylene resin is a crystalline polymer having an isotactic, syndiotactic structure, or the like, or an α-olefin other than propylene and a small amount of propylene, for example, ethylene, 1-butene, 1-hexene, 4-methyl-1 Copolymers, such as pentene, comprising propylene in the form of propylene homopolymers, block or random copolymers.

The melt index of the polypropylene resin is suitably 0.1 to 100 g / 10 minutes, the crystalline homopolypropylene is the best and can be used alone or in combination with the alpha olefin copolymer resin.

Styrene-based block copolymer resins are used to achieve good flow properties, improved physical properties and low hardness. The styrene block copolymer resins are hydrogenated and do not have double bonds, so they have excellent heat resistance and weather resistance. These types include styrene-ethylene / butylene-styrene [SEBS], styrene-ethylene / propylene-styrene [SEPS], and block copolymers of styrene-ethylene / ethylene-propylene-styrene [SEEPS].

Such styrenic block copolymer resins are preferably those in which the content of the amorphous polystyrene block is in the range of 15 to 50% by weight. Although the styrene block copolymer resin is mainly used by blending independently, you may use 2 or more types.

The content of at least one styrenic block copolymer resin selected from the group consisting of these may be 5 to 200 parts by weight, preferably 5 to 100 parts by weight, and more preferably 10 to 75 parts by weight based on 100 parts by weight of silicone rubber. .

If the amount is less than 5 parts by weight, there is little effect to be expected, and if it exceeds 200 parts by weight, side effects such as increased adhesiveness may occur.

Paraffin-based white oil may be used as a mineral oil having excellent thermal stability and excellent compatibility with matrix resin.If some aromatic components are mixed with paraffin-based white oil, the oil may become yellowish brown when exposed to an environment such as heat processing. In addition, since the use should be limited to food containers, such as environmentally friendly, it is preferable to use a mineral white oil with almost no aromatic components to compensate for these problems.

Especially for mineral white oils used as food contact and medical products, it is advisable to use FDA-approved ingredients that can also be used for food.

In the present invention, the white oil content is 0.5 to 100 parts by weight or less, preferably 0.5 to 60 parts by weight based on 100 parts by weight of silicone rubber.

If it is less than 0.5 parts by weight, it is ineffective, and if it is more than 100 parts by weight, flowability may be improved and low hardness may be achieved, but an undesired phenomenon may occur in which oil is leached and carried out for a long time.

When styrene copolymer resin and mineral white oil are used, homogeneous dispersion may be achieved even when a compatibilizer is not used, but a compatibilizer may be optionally used.

As the compatibilizer, maleic anhydride copolymer may be used. More specifically, the maleic anhydride copolymer may be an ethylene-maleic anhydride copolymer, a propylene-maleic anhydride copolymer, an alpha olefin-maleic anhydride copolymer, or a maleic anhydride styrene-ethylene. -Butylene-styrene copolymers, etc. These copolymers are formed by grafting maleic anhydride to a base resin in an extruder or the like or by random copolymerization in a polymerization reactor.

The content of the compatibilizer is 20 parts by weight or less based on 100 parts by weight of the silicone rubber, and preferably 10 parts by weight or less.

If it exceeds 20 parts by weight, an undesirable phenomenon may occur in which a gel is formed inside the composition during dynamic crosslinking.

In the present invention, the dynamic crosslinking is carried out through a hydrosilylation reaction, and as the addition reactive crosslinking agent, an organic polymer siloxane having a group in which hydrogen is bonded to two or more silicon in the molecule is used, and Si in the crosslinking agent is used. It is preferable to apply so that the molar ratio of the -H component and the Si-vinyl component in the polysiloxane is in the range of 1 to 5.

The content of the crosslinking agent is 0.1 to 10 parts by weight based on 100 parts by weight of silicone rubber, preferably 0.2 to 7.5 parts by weight.

The reaction catalyst may be composed of a karstedt's catalyst in the form of a complex solution of organic siloxane and platinum to dynamically crosslink silicon.

The content of the reaction catalyst is 0.05 to 100 ppm of platinum metal atoms, preferably 0.1 to 50 ppm, based on 100 parts by weight of the silicone rubber.

In the thermoplastic elastomer composition of the present invention, various kinds of additives used in conventional polymer blending may be additionally used, and thus physical properties may be somewhat modified. Such additives include inorganic fillers such as diatomaceous earth, quartz and calcium carbonate, flame retardants such as wollastonite and metal hydroxides, and blowing agents, processing aids, mold release agents, heat stabilizers, antioxidants, pigments, UV stabilizers and the like.

In the method of preparing the thermoplastic elastomer composition of the present invention, the melt kneading and the dynamic crosslinking are completed in a twin screw extruder or an internal mixer rotating in the same direction, or the base of the substrate is melt kneaded in an internal mixer in one step. There is a two-step method for producing a semi-finished product and dynamic crosslinking in a two-screw extruder that rotates the semi-finished product and the catalyst in the same direction in two steps. At this time, the temperature at the time of dynamic crosslinking is adjusted to 160-230 degreeC.

In the twin screw extruder, a continuous manufacturing process is good, and since the crosslinking is performed during melt kneading, the longer the length of the screw is, the better the properties are, and L / D is more preferably 48 or more.

The raw material input may add a crosslinking agent, a crosslinking adjuvant, etc. at the beginning or intermediate | middle as needed, and may mix and master-batch more with the same high molecular material used here. For example, by mixing two or more kinds of materials such as styrene-based block copolymer, white oil, silicone gum, and crosslinking agent in a master batch, the amount of power, processing time, quality and thermal history of the product can be reduced. You may.

The above-described manufacturing method may be used to adjust and modify the process, and the process is not limited thereto.

Experiment example

<Components Used>

The properties of the components used in the experiments of the present invention are as follows.

① Silicone base is 30% by weight of fumed silica (Evonik AEROSIL 300) having a surface area (BET) of about 300 m 2 / g to 64.5% by weight of methylvinyldimethylpolysiloxane having a molecular weight of about 700,000 cPs and a vinyl content of about 0.1%. And a silicone rubber base prepared from 5.5% by weight of dimethylpolysiloxane of a hydroxy end bond having a viscosity of 40 cSt.

(2) Polyolefin resin 1 is homopolypropylene, Hanwha Total HY-301 with a melt index of 3.0, and polyolefin resin 2 is an alpha olefin copolymer resin. ExxonMobil V-6202, polyolefin resin copolymerized with ethylene on a propylene base under a metallocene catalyst. 3 is an alpha olefin copolymer resin, LG Chem POE LC100 copolymerized with octene on an ethylene base under a metallocene catalyst.

SEBS is styrene-ethylenebutylene-styrene block copolymer resin, Kraton G1651.

④ Paraffin oil is FOMI 350, paraffinic white mineral oil with kinematic viscosity of about 70cSt.

⑤ Compatibilizer is Fusabond P-613, DuPont maleic acid grafted polypropylene resin.

⑥ Crosslinking agent 26% by weight of trimethylsiloxy end-bonded polymethylhydrogensiloxane having about 1.5% by weight of hydrogen bonded to silicon, 5% by weight of tetravinyl tetramethylsiloxane, 69% by weight of dimethylvinyl end-bonded polydimethylpolysiloxane Crosslinking agent prepared from.

⑦ The catalyst is a caste catalyst, which is a platinum (0) -1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Platinum (0) -1,3-divinyl-1,1,3, A catalyst prepared from 1% by weight of a 2% dilution solution of 3-tetramethyldisiloxane complex, 3% by weight of tetravinyltetramethylsiloxane, and 96% by weight of dimethylvinyl terminated polydimethylpolysiloxane.

Comparative Examples and Examples 1 to 4 were prepared from the components summarized above, and the properties thereof were measured and shown in Table 2.

Ingredients (parts by weight) Comparative example Example 1 Example 2 Example 3 Example 4 Remarks Silicone base 100 100 100 100 100 Polyolefin Resin 1 43 30 30 20 20 HPP Polyolefin Resin 2 30 30 30 - Copolymer Resin Polyolefin Resin 3 - - - 30 Copolymer Resin Compatibilizer 5 5 5 5 Crosslinking agent 2.0 2.0 2.0 2.0 2.0 catalyst 0.5 0.5 0.5 0.5 0.5 SEBS 20 20 30 30 White oil 10 20 30 40

<Production of comparative example>

Comparative Example shown in Table 1 Based on the 80% filling rate in a 3 liter internal mixer heated to 190 ℃ according to the content of the composition, a silicon base and a crosslinking agent was added, kneading for about 5 minutes at a rotor speed of 60rpm, polyolefin resin 1 is added and melt kneaded uniformly for about 10 minutes.

Thereafter, after the catalyst was added while the rotor speed was maintained at 60 rpm, the silicone rubber was dynamically crosslinked for about 7 minutes. At this time, the peak temperature at the time of dynamic crosslinking reached 195-210 degreeC.

The test sample of the dynamic crosslinked comparative example was prepared and cut into a sheet in an open mill, and made into a 200 mm 200 mm sheet having a thickness of 2 mm in a press at 200 ° C., and then processed into various specimens for evaluation of physical properties.

<Production of Examples 1 to 4>

According to the composition of the embodiment shown in Table 1, the polyolefin resin 1,2,3 and SEBS, white oil, compatibilizer, crosslinking agent was added to the 3 liter internal mixer heated to 190 ℃ based on the 80% filling rate and the rotor speed was increased. After operating for about 7 minutes at 60 rpm, the silicon base is added and melt mixed for 10 minutes.

Then, after the catalyst was added while maintaining the rotor speed at 60 rpm, the composition of Examples 1 to 4 was dynamically crosslinked for about 7 minutes. At this time, the peak temperature at the time of dynamic crosslinking reached 195-205 degreeC.

Dynamically crosslinked test samples of Examples 1 to 4 were prepared and processed in the same manner as in Comparative Examples.

Experimental Characteristics and Methods

Experimental characteristics and methods used are as follows, and the results are shown in Table 2.

Hardness Shore A: ASTM D2240, measured after 5 seconds

Tensile strength: ASTM D412

Elongation: ASTM D412

100% Modulus: ASTM D412

Compression set (22hrs @ 100 ℃): ASTM D395-B, 12.7mm thick sample

-Thermal Stability (Yellow): Check the discoloration of the prepared specimen surface

-Whitening phenomenon: Fold the sheet 180 degrees and open it, and then observe the whitening phenomenon of the folded part.

-PP adhesiveness: After placing the PP material and the composition sheet up and down under test and hot press compression molding at 190 ° C, the adhesiveness is evaluated by whether or not cohesive failure is not interfacial failure.

Processability (Extruded Appearance): In order to observe the smooth appearance of the extruded product and the presence of uneven gel, a single nipple extruder having a diameter of 20 mm and L / D = 20 was mounted with a long nipple tube die. Extrude at 70 rpm to observe the surface of the extrudate

characteristic Comparative example Example 1 Example 2 Example 3 Example 4 Remarks Hardness Shore A 92 65 55 40 34 Tensile strength, kgf / ㎠ 71 79 75 71 65 Elongation,% 179 550 650 750 730 100% modulus, kgf / ㎠ 62 25 15 10 9 Compressed permanent reduction rate,% 41 33 31 28 32 22hrs @ 100 ℃ Thermal Stability (Yellow) Discoloration none none none none Whitening phenomenon With department store none none none none PP adhesive ○ ○ ○ ○ ○ ○ Good (inner surface destruction) Machinability (Appearance) △ Good Good Good Good △ gel production,
Appearance Rough

<Evaluation>

For the comparative example, as shown in Table 2, about 70% by weight of the silicone base in the composition was used, but the Shoa hardness was very high as 92, and the elongation was as low as 179%. This shows that polypropylene alone is not easy to low hardness.

In addition, there is a tendency to slightly yellowing and whitening phenomenon during processing, and the flowability is not good, so the appearance of extrusion processing tends to be not smooth and rough gel-like projections on the surface.

In the case of the embodiment, as shown in Table 2, there is no yellowing phenomenon at a high temperature and the flowability is excellent, so the extrusion processing appearance is excellent, low hardness is realized, and exhibits good physical properties such as compression set.

As described above, since the elastomer composition of the present invention can be made low in hardness, the elastomer composition of the present invention can be specialized in food products, such as food containers, food products such as high elastic gaskets, medical elastic tubes and sealing plugs, medical supplies, wire insulation materials, and automobile products. It can be applied to various fields.

In addition, the processability and high temperature melt flowability is improved to facilitate the production of complex molded articles, and the thermal stability during the manufacturing can be avoided to prevent the use of antioxidants, food contact, etc. have no influence on the human body.

In the above description, the embodiment of the present invention has been described, but various changes can be made at the level of those skilled in the art. Therefore, the scope of the present invention should not be construed as being limited to the above embodiments, but should be construed by the claims described below.

Claims (7)

An olefinic thermoplastic silicone elastomer composition based on an olefinic thermoplastic resin and a silicone rubber and manufactured by dynamic crosslinking by a hydrosilylation reaction,
The elastomer composition, based on 100 parts by weight of the silicone rubber, 5 to 200 parts by weight of styrenic block copolymer resin and 0.5 to 100 parts by weight of mineral white oil, characterized in that the dynamic crosslinked olefin thermoplastic silicone elastomer composition . In claim 1,
The elastomer composition comprises 10 to 200 parts by weight of polyolefin resin, 20 parts by weight or less of a compatibilizer, 0.1 to 10 parts by weight of an addition-curable crosslinking agent, and a catalyst having a metal atom of 0.05 to 100 ppm based on 100 parts by weight of the silicone rubber. A dynamically crosslinked olefinic thermoplastic silicone elastomer composition. In claim 1 or 2,
The styrene block copolymer resin is used alone or in combination of styrene-ethylene / butylene-styrene block copolymers, styrene-ethylene / propylene-styrene block copolymers, and styrene-ethylene / ethylene-propylene-styrene block copolymers. A dynamic crosslinked olefinic thermoplastic silicone elastomer composition, characterized in that it is used in admixture. In claim 2,
The polyolefin resin is a dynamic crosslinked olefin thermoplastic silicone elastomer composition, characterized in that the polypropylene, polyethylene, alpha olefin copolymer resins are used alone or in combination of two or more. In claim 2,
The compatibilizer is a dynamic crosslinked olefin, characterized in that it is selected from ethylene-maleic anhydride copolymer, propylene-maleic anhydride copolymer, alpha olefin-maleic anhydride copolymer, maleic anhydride styrene-ethylene-butylene-styrene copolymer Thermoplastic Silicone Elastomer Compositions. Based on olefinic thermoplastic resin and silicone rubber, it is manufactured by dynamic crosslinking by hydrosilylation reaction,
Based on 100 parts by weight of the silicone rubber, it is composed of a thermoplastic silicone elastomer composition containing 5 to 200 parts by weight of styrenic block copolymer resin and 0.5 to 100 parts by weight of mineral white oil to be used for food contact and medical use Molded article characterized in that. In claim 6,
The elastomer composition, a molded article, characterized in that it comprises a compatibilizer of 20 parts by weight or less based on 100 parts by weight of the silicone rubber.