JP2014156568A - Resin composition for silane crosslinked compact and compact using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem associated with an extrusion compact of water crosslinked polyolefin-based resin composition using a linear low-density polyethylene which is inexpensive as a main constituent that it has bad surface smoothness and it cannot be produced at high speed.SOLUTION: Provided is a resin composition for a silane crosslinked compact including a silane-modified polyolefin-based resin, in which the polyolefin-based resin is formed of 65-98 pts.mass of a linear low-density polyethylene and 35-2 pts.mass of a polypropylene, as a main constituent.

Description

  The present invention relates to a resin composition capable of silane crosslinking by contact with moisture in the presence of a silanol condensation catalyst, and a molded body using the same, and particularly, a coating having surface smoothness and economy by extrusion molding. The present invention relates to a silane-crosslinked polyolefin resin composition capable of producing an electric wire / cable and a coated electric wire / cable using the same.

  Needless to say, electric wires and cables are used as a power transport medium, but the amount of use in the field of information transmission has increased due to the development of an information-oriented society and the use of electronics for all types of equipment. For this reason, except for special cases, the covering materials for electric wires and cables, which are mostly made of plastic materials, also play an important role, and are the original purpose of electric wires and cables: electrical insulation, protection, ease of handling, and safety. In addition to the above, aesthetics, economic efficiency, environmental friendliness, etc. have been demanded.

  Power transmission media include transmission lines that send electricity generated at power stations to substations in the areas where they are consumed, distribution lines that distribute electricity that has been reduced to a predetermined voltage at substations to factories, buildings, and homes. It can be divided into wiring used in buildings and homes, and electric wires for special equipment used in ships, aircraft, automobiles, etc.

  High-voltage power transmission / distribution devices have a somewhat complicated covering structure, but underground transmissions use cross-linked PE with excellent electrical properties and mechanical strength as the inner insulator, and the outer sheath As polyvinyl chloride (PVC) or PE. Some of the inner cross-linked PEs may be applied with electron beam cross-linking that irradiates an electron beam or chemical cross-linking using a peroxide, but can be cross-linked by contact with moisture in the presence of a silanol condensation catalyst. Often water cross-linked PE is used.

  For power cords such as home appliances and OA equipment, thermoplastic elastomer (TPE) is often used for reasons such as good moldability, but in the case of electric wires used in high temperatures, the coating is made of polyethylene terephthalate In addition to (PET) film, crosslinked PE is also used. Water-crosslinked PE is often applied to this crosslinked PE.

  On the other hand, as an information transmission medium, a connecting wire between electronic devices in offices and homes, in particular, a TV lead wire or the like uses PE coating or rubber for its outer sheath. PE is widely used.

  In recent years, the use of electric wires in automobiles has increased due to the progress of electronics and hybridization. The main coating material is PVC, but as the coating material requiring heat resistance, PET and water-crosslinked PE are also increasing.

  Thus, water cross-linked PE is now an indispensable insulating material. In the future, it is expected that it will be used in place of PVC containing chlorine from the viewpoint of environmental properties, and it will be used in place of expensive PET from the viewpoint of economy.

  As such a water-crosslinked PE, any of high-density PE (HDPE), linear low-density PE (LLDPE), and low-density PE (LDPE) can be used. . HDPE is a linear polymer with no branching, so it has a high degree of crystallinity and is most excellent in electrical, mechanical, thermal, and chemical properties required for wire coating materials. However, there is a problem of surface smoothness called melt fracture in which irregularities are formed on the surface by extrusion molding. This is a peculiar swelling phenomenon seen in the case of pore extrusion such as wire coating processing, and is presumed to be due to the Balas effect (see Non-Patent Document 1). Since LDPE is a branched polymer having long branches, it has a low crystallinity, is easy to mold and is excellent in flexibility, but has poor tensile strength, heat resistance, etc. . LLDPE is a linear polymer having a short branch and exists in the middle of HDPE and LDPE due to its structure, but has the problem of surface smoothness like HDPE.

  However, LLDPE produced by copolymerization of ethylene and α-olefin is superior to LDPE in mechanical strength, heat resistance, and hot sealability, seal strength, impact resistance, hot tack, etc. However, since it surpasses Surlyn (registered trademark: PE ionomer), the conventional LDPE has been replaced by LLDPE, mainly in packaging materials, and a great advantage has been obtained in terms of economy. Therefore, in the field where economy is required, such as coated electric wires and cables, from the viewpoint of raw material prices, PE for film that is used in large quantities as packaging materials, that is, LLDPE with a low melt flow ratio (MFR) is used. It has become necessary to use it as a water-crosslinking PE.

  Therefore, in order to solve the problem of the surface smoothness of the LLDPE, improvements such as JP-A-55-128441, JP-A-60-139713, and JP-A-9-306241 have been performed. The following issues remain.

  JP-A-55-128441 improves the problem of surface smoothness by introducing polypropylene (PP) into LDPE having an MFR of 2.0, but the effect on LLDPE has not been confirmed. Inferior mechanical and thermal properties as a coating material.

  JP-A-60-139713 improves the extrudability in the molding process of LLDPE, but does not mention surface smoothness. Furthermore, Japanese Patent Laid-Open No. 9-306241 discloses an improvement in surface smoothness at a coated wire production speed of 40 m / min or less, but the effect in practical high-line production at which problems occur is unconfirmed.

  Thus, when a coated electric wire / cable is produced by extrusion molding using a silane cross-linked resin composition containing LLDPE as a main component, the problem of surface smoothness has not yet been solved.

Japanese Patent Laid-Open No. 55-32091 JP-A-60-139713 JP-A-9-306241 JP-A-10-120797

Yasushi Oyanagi, Engineering Plastics-Characteristics and Processing-, p.74, 1985.

  The present invention is a resin composition that can produce a silane-crosslinked resin molded article having LLDPE as a main component and having surface smoothness and economy in addition to electrical, mechanical, thermal, and chemical properties. And a molded body thereof. In particular, silane-crosslinked polyolefin for moldings that can produce coated wires and cables with surface smoothness and economy in addition to electrical, mechanical, thermal, and chemical properties. An object of the present invention is to provide a resin composition and a coated electric wire / cable using the resin composition.

  The present inventors, by extrusion molding of a silane cross-linked polyolefin resin composition mainly composed of a silane-modified polyolefin resin of a resin composed of 65 to 98 parts by mass of LLDPE and 35 to 2 parts by mass of polypropylene (PP), The inventors have found that a silane-crosslinked resin molded article having surface smoothness and economy in addition to electrical, mechanical, thermal, and chemical properties can be produced, and the present invention has been completed.

  The present invention makes it possible to form a melt fracture-free appearance that could not be achieved by conventional LLDPE extrusion without compromising electrical, mechanical, thermal, and chemical properties. In particular, according to the present invention, a coated electric wire / cable can be produced at a high speed, so that it is possible to provide a coated electric wire / cable excellent in economic efficiency due to an improvement in productivity in addition to a reduction in raw material price.

  The silane cross-linked polyolefin resin composition of the present invention is composed of at least LLDPE, PP, an organic alkoxysilane compound having an unsaturated double bond, a radical generator, a silanol condensation catalyst, and an antioxidant. Each of the following materials is preferably used.

  As described above, the LLDPE of the present invention is a film application that emphasizes suitability as a packaging material such as heat sealability and inflation moldability from the viewpoint of raw material price, and has various MFRs of 0.7 to 5.0. LLDPE can be used, but 1.0 to 4.0 is more preferable. Such an LLDPE is preferably an ethylene-α-olefin copolymer produced by various synthesis methods such as a gas phase polymerization method or a solution polymerization method, and specifically, an ethylene-butene copolymer, an ethylene-hexene copolymer, or the like. It is preferable to use a copolymer, an ethylene-octene copolymer, or the like. Among these, an ethylene-hexene copolymer and an ethylene-octene copolymer are more preferable. Furthermore, LLDPE polymerized using a metallocene catalyst is the mainstream of current packaging materials, and is more preferable from the viewpoints of characteristics and economics required as a coating material for electric wires and cables.

  Examples of such inexpensive LLDPE for film market distribution are as follows. For example, commercially available gas phase polymerization method LLDPE includes Novatec (registered trademark) LL and Novatec (registered trademark) C6 for films made by Nippon Polyethylene. Furthermore, as a commercially available solution polymerization method LLDPE, there are Neozex (registered trademark), Ultozex (registered trademark), Moretec (registered trademark), Evolue (registered trademark), etc. manufactured by Prime Polymer Co., Ltd.

  The above-mentioned various LLDPEs can be used alone, but two types of LLDPE can also be mixed and used at a ratio of 90:10 to 70:30, and one of these types of LLDPE has a melting point of 100 ° C. or less. Can also be used. When the blending ratio is less than this ratio or when the blending ratio is exceeded, there is no effect of improving the surface smoothness. Specifically, an ethylene-butene copolymer, an ethylene-hexene copolymer, and an ethylene-octene copolymer are selected, and an ethylene-hexene copolymer and an ethylene-octene copolymer are suitable.

  In addition, PE rubber, which is an ethylene-α-olefin copolymer having a melting point of 40 to 80 ° C., called thermoplastic elastomer (TPE), is mixed with various LLDPEs in a ratio of 97: 3 to 80:20. It can also be used. In addition, ethylene-ethyl acrylate (EEA) resin, ethylene-butyl acrylate (EBA) resin, ethylene-vinyl acetate (EVA) resin, and the like can be applied in the same manner. Among them, EA content is 9% or more. EEA resin and EVA resin having a VA content of 9% or more are suitable. When the amount is less than the above blending amount, there is no effect of improving the surface smoothness. When the blending amount is larger than the above blending amount, thermal and mechanical properties are deteriorated. Also, a resin such as TPE can be mixed. Thereby, the flexibility which LLDPE does not have is provided and there exists an effect which improves the softness | flexibility of a covered electric wire and a cable, a flexibility, etc. Examples of such resins include TPE for Dow Engage, EEA and EBA resins for DuPont Elvalloy (registered trademark), Nippon Unicar EEA, and EVA resin for Japan Polyethylene. Novatec (Registered Trademark) EVA, Everflex (Registered Trademark) manufactured by Mitsui DuPont Polychemical Co., Ltd., Nippon Unicar Co., Ltd., etc. are commercially available.

  The problem of the surface smoothness of the molded product that occurs when the LLDPE is extruded can be solved without impairing the characteristics required of the coated wire / cable, mainly by blending an appropriate amount of PP.

  PP includes a homopolymer (h-PP) of a PP homopolymer, random PP (r-PP) which is a copolymer with a small amount of ethylene and / or 1-butene, and a rubber component as h-PP or There are blocks PP (b-PP) dispersed in r-PP, any of which can be used. Among these, r-PP can eliminate melt fracture that occurs when a coated electric wire / cable is produced at a higher speed. In particular, r-PP which is a copolymer of ethylene-propylene is preferable. Further, this r-PP also preferably has an MFR of 5 or more, more preferably 15 or more, and most preferably 25 or more.

  It is effective to use PP with respect to LLDPE at a blending amount of 35 to 2 parts by mass with respect to 65 to 98 parts by mass of LLDPE, but it is used with 22 to 2 parts by mass of PP with respect to 78 to 98 parts by mass of LLDPE. More preferably, it is more preferably used at 14 to 3 parts by mass of PP with respect to 86 to 97 parts by mass of LLDPE. When PP is less than 2 parts by mass, there is no effect of improving the surface smoothness, and when it is 35 parts by mass or more, mechanical and thermal characteristics are deteriorated. In addition, the compounding quantity of this PP is designed as LLDPE in the case of LLDPE containing 2 types of LLDPE and TPE.

  For example, as marketed products of such PP-based resins, Novatec (registered trademark) PP manufactured by Nippon Polypropylene, Polypropylene Sun Allomer manufactured by Sun Allomer, Sumitomo Noblen (registered trademark) manufactured by Sumitomo Chemical Co., Ltd. and Prime Poly Pro manufactured by Prime Polymer Co., Ltd. There are products such as (registered trademark).

  The reason why the melt fracture is eliminated by such PP blending is the melt viscoelastic behavior due to the molecular structure including the branched structure, copolymerization component, molecular weight distribution, etc. of the polyolefin resin composition However, it is not clear. The cause of the melt fracture being eliminated by the present invention is not clear, but is estimated as follows.

  First, the melt fracture on the surface of the extrusion molded body rises due to the normal stress effect peculiar to the viscoelastic body when the resin melted in the extrusion machine goes out to the outside from the nozzle, and its shape changes from the melt to the solid. I guess that it was left even if it became. Based on this assumption, the more easily crystallized, such as linear molecules, polymers with a narrow molecular weight distribution, and polymers with uniform components, the greater the solidification rate at which the state changes from a melt to a solid. Fracture is likely to occur. In fact, it is generally said that melt fracture tends to be formed in the order of LDPE, LLDPE, and HDPE. That is, melt fracture is solved by controlling the solidification rate of the polyolefin resin. In particular, the Balas effect (see Non-Patent Document 1), which is a peculiar swelling phenomenon seen in the case of pore extrusion as in the case of wire coating in extrusion molding, becomes more prominent as high-speed molding is performed. It seems to come. Therefore, it is presumed that the solidification rate suitable for extrusion molding could be controlled by the polyolefin resin composition of the present invention.

  On the other hand, the present invention is a silane-modified polyolefin resin composition capable of silane crosslinking by contact with moisture in the presence of a silanol condensation catalyst, and the crosslinking component is an unsaturated double compound under a radical generator. It is introduced by a radical reaction of an organic alkoxysilane compound having a bond.

  Examples of the alkoxysilane compound that can be used in the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, and allyltrimethoxy. Silane, allyltriethoxysilane and the like can be mentioned, and vinyltrimethoxysilane and vinyltriethoxysilane are preferable. The blending amount is preferably 0.2 to 4.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the polyolefin resin.

  The radical generator used in the present invention is preferably an organic peroxide. For example, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert- Butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4 4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide Lauroyl peroxide , And it may be mentioned tert- butyl cumyl peroxide and the like. Of these, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl-2, and 5- Most preferred is di- (tert-butylperoxy) hexyne-3. This blending amount is preferably 0.05 to 4.0 parts by mass, and more preferably 0.07 to 3.0 parts by mass with respect to 100 parts by mass of the polyolefin resin.

  Examples of the silanol condensation catalyst that can be used in the present invention include dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin dilaurate, zinc stearate, lead stearate, barium stearate, calcium stearate, Examples include sodium stearate, lead naphthenate, lead sulfate, zinc sulfate, and organic platinum compounds. In particular, dibutyltin dilaurate and dioctyltin dilaurate are preferred. The blending amount is preferably 0.005 to 0.2 parts by mass and more preferably 0.01 to 0.1 parts by mass with respect to 100 parts by mass of the polyolefin resin.

  Examples of the antioxidant that can be used in the present invention include 4,4′-dioctyl diphenylamine, N, N′-diphenyl p-phenylenediamine, and 2,2,4-trimethyl-1,2-dihydro. Amine antioxidants such as polymers of quinoline, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-t Phenolic antioxidants such as 1-butyl-4-hydroxyphenyl) propionate and 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene Agent, bis (2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl) sulfide, 2-mercaptobe Zone imidazole and zinc salts, and, pentaerythritol - tetrakis (3-lauryl - thiopropionate) sulfur-based antioxidants such as and the like. In particular, a findnt phenolic antioxidant is preferred, and specific examples include pentaerythritol-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate). The blending amount is preferably 0.5 to 1.0 part by mass with respect to 100 parts by mass of the polyolefin resin.

  In the present invention, in addition to the above components, a metal deactivator, weathering agent, lubricant, colorant, or other additive can be appropriately blended within a range not impairing the object of the present invention.

  Metal deactivators include N, N′-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, 3- (N-salicyloyl) amino-1,2,4. -Triazole, 2,2′-oxamidobis- (ethyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and the like.

  Examples of the weathering agent include general weathering agents such as a light stabilizer (for example, a hindered amine-based light stabilizer) or an ultraviolet absorber (for example, a benzotriazole-based ultraviolet absorber, carbon black).

  Examples of the lubricant include hydrocarbons, fatty acids, fatty acid amides, esters, alcohols, metal soaps, silicones, and the like, and hydrocarbons and silicones are particularly preferable.

  Examples of the method for producing the silane-crosslinked polyolefin resin composition of the present invention and a molded body using the same using such raw materials include, but are not limited to, the following methods. .

  First, a predetermined amount of LLDPE, PP, an organic alkoxysilane compound having an unsaturated double bond, and a radical generator are mixed with a Henschel mixer or the like. Next, this is kneaded with an extruder under predetermined conditions and then pelletized (A, silane grafting step). On the other hand, a silanol condensation catalyst, an antioxidant and the like are kneaded with a small amount of LLDPE and a Banbury mixer and then pelletized (B). Finally, (A) and (B) can be mixed and stirred with a tumbler or the like to produce a desired silane-crosslinked polyolefin resin composition.

  The resin composition produced in this manner is fed into a general extruder, and in the process of being extruded by a screw through a heated cylinder, the remaining radical reaction and alkoxysilane ion reaction proceed simultaneously. While being pushed out from the head, the crosslinking reaction is completed with moisture, and a crosslinked product can be obtained. When a resin is coated on an electric wire, a covered electric wire / cable is manufactured.

  In particular, the present invention is not limited to the above production method, and it is possible to omit the silane grafting step of modifying the polyolefin resin with silane. This simplifies the production process and makes it possible to produce a silane cross-linked molded article that is more economical. The reason why this step can be omitted is not clear, but is thought to be related to the melt viscoelastic behavior of the polyolefin-based resin that was able to solve the above-described melt fracture. That is, since the melt viscosity of the resin composition of the present invention is low, the mobility of radicals necessary for silane grafting is increased, and it is assumed that a sufficient graft reaction has occurred in the extruder during extrusion molding.

  Hereinafter, although it demonstrates in detail based on an Example, this invention is not limited to these.

[sample]
The PE resin and rubber, PP resin, organic alkoxysilane compound having an unsaturated double bond, radical generator, silanol condensation catalyst, and antioxidant used in this example are shown in Table 1.

[A manufacturing process]
PE-based resin and rubber, PP-based resin, organic alkoxysilane compound having an unsaturated double bond, and a radical generator are stirred at a predetermined blending amount for 5 minutes using a Henschel mixer, and an extruder under the following conditions: And then pelletized.
Examples 1 to 12, 16, 17, and Comparative Example φ 70 mm, L / D 35, was used and kneaded at a screw rotation speed of 150 rpm, a discharge rate of 150 kg / h, and a kneading temperature of 200 ° C.
○ Examples 13-15
Using a single screw extruder with a diameter of 90 mm and L / D30, kneading was performed at a screw rotation number of 35 rpm and a kneading temperature of 200 ° C.
[B manufacturing process]
The mixture was kneaded at 200 ° C. for 5 minutes with a Banbury mixer and pelletized.
[A and B mixing process]
A and B were mixed at a predetermined ratio, and stirred and mixed with a tumbler for 10 minutes.

[Wire production process]
Using an extruder with a cylinder diameter of φ70 mm and L / D25, the extrusion temperature was set as follows: cylinder: 190 ° C., flange: 200 ° C., head: 210 ° C., die: 220 ° C., and linear speeds of 50, 100, and 150 m / The conductor was coated with a resin in min. The conductor was a 1 / 0.8 A annealed copper wire, the thickness of the coating resin was 0.4 mm, and the outer shape was about φ1.6 mm.

[Crosslinking process]
It was immersed in 60 degreeC warm water for 24 hours.

[Evaluation]
Heat deformation: Based on JIS C 3005, the test was performed at a test temperature of 120 ° C. and a load of 5 N. A deformation rate of 40% or less was accepted (◯), and the others were rejected (×).
○ Hot set: Based on JIS C 3660-2-1, the test temperature is 200 ° C., the load is 20 N / mm ² , the load time is 15 min, the elongation during heating is 100% or less, and the permanent elongation after cooling is 25%. The following were set to pass (◯), and the others were set to fail (x).
○ High linear velocity manufacturability: The appearance of each linear velocity was visually evaluated. A product having a very good external appearance was evaluated as ◯, a product having no problem, a product having a slightly poor external appearance was evaluated as Δ, a product having a problem in product was evaluated as ×, and a product having a linear speed of 100 m / min was evaluated as acceptable.
○ Low-temperature property A (low-temperature winding property): Based on JIS C 3005, after winding around a winding mandrel at a test temperature of −45 ° C., ○ is indicated as no crack and ○ is indicated otherwise. Although it was not an indispensable condition depending on the application, it was a reference test irrelevant to pass / fail, but it was carried out for comparison of characteristics with a conventional silane cross-linked resin molded product.
○ Low temperature B (cold resistance): Based on JIS C 3005, the test temperature was -65 ° C. As the sample, a sheet having a thickness of 2 mm produced under the same equipment and extrusion conditions as the electric wire was used. After the test, visual evaluation was performed, and a case where there was no change was indicated as ◯, a case where a pinhole was observed was indicated as △, and a case where there was a crack, a crack or the like was indicated as ×. Although this test was not an essential condition, it was a reference test that was unrelated to pass / fail, but it was carried out for comparison of characteristics with a conventional silane cross-linked resin molded product.

[result]
Each resin composition was produced by the method described above, and the evaluation results of the covered electric wires obtained through the electric wire manufacturing process and the crosslinking process are summarized in Tables 2 and 3. It has been confirmed that there is no change in the evaluation results depending on the method for producing the resin composition.

[Examples 1 to 6] and [Comparative Examples 1 to 4]
As is clear from Examples 1 to 6 and Comparative Examples 1 to 3, the blending amount of PP35 to 2 parts by mass with respect to LLDPE 65 to 98 parts by mass can eliminate the melt fracture. From the viewpoint of the relationship with low temperature characteristics, it is more preferably used at 22 to 2 parts by mass of PP with respect to 78 to 98 parts by mass of LLDPE, and more preferably at 14 to 3 parts by mass of PP with respect to 86 to 97 parts by mass of LLDPE.

[Example 3 and Examples 7 to 10]
Example 3 and Examples 7 to 10 show the influence of the type of PP. Any of r-PP, b-PP, and h-PP can be used, but r-PP is more preferable, and from the result of high linear velocity manufacturability, the larger the MFR, the more effective the reduction of melt fracture It is.

[Examples 3, 11, and 12]
In Example 11, the influence of the blending amount of the antioxidant was examined. It turns out that there is no influence even if 0.4 mass part antioxidant is added with respect to 100 mass parts of polyolefin resin. In Example 12, although the influence of the kind of LLDPE was evaluated, a big change was not seen and LLDPE for films can be widely used, but the thing of MFR 1.0-4.0 is more preferable.

[Example 3, 13 to 15]
In this experiment, the influence of the conditions of [A silane grafting step] on each evaluation item was examined. As is clear from the table, it was not affected at all.

[Examples 3, 16, and 17]
In Example 16, when two types of LLDPE were mixed as LLDPE, Example 17 was an ethylene-α-olefin copolymer, but was mixed with TPE that is rubbery and has a very low density and melting point. The result is shown. Although the visual evaluation result shows no significant difference from Example 3, Examples 16 and 17 were superior in surface smoothness. It can be seen that LLDPE and TPE having a melting point of 100 ° C. or lower are effective.

  The resin composition for a silane cross-linked molded article of the present invention has a low raw material price, enables high-speed production, and does not necessarily require a reaction step for grafting an alkoxysilane compound to a polyolefin resin. Coated wires / cables with excellent surface smoothness despite using LLDPE with excellent electrical, mechanical, thermal and chemical properties as the main component. Can be manufactured. Since it is a resin composition having such characteristics, it is not limited to coated electric wires / cables, and can be widely applied to optical cords, power plugs, connectors, sleeves, boxes, tapes, tubes, sheets, and the like.

Claims (6)

  Silane cross-linking characterized in that the main component is a polyolefin resin obtained by silane modification of a polyolefin resin composed of 65 to 98 parts by mass of linear low density polyethylene (LLDPE) and 35 to 2 parts by mass of polypropylene (PP). Type polyolefin resin composition.   The silane cross-linked polyolefin resin composition according to claim 1, wherein the LLDPE is an ethylene-α-olefin copolymer having a melt flow rate (MFR) of 0.7 to 5.0.   The silane cross-linked polyolefin resin composition according to claim 1, wherein the LLDPE is polymerized using a metallocene polymerization catalyst.   The silane cross-linked polyolefin resin composition according to claim 1, wherein the PP is a random PP.   The silane cross-linked polyolefin resin composition according to claim 1, wherein the PP has an MFR of 5 or more. A molded body comprising the resin composition according to any one of claims 1 to 5.