JP2000034383A - Silane-cross-linkable polyolefin resin composition and insulation cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of providing a molding product having the surface excellent in smoothness, and heat resistance, and enabling an insulation cable to be formed by covering sheath just after the wire-covering when used as the wire-covering by using a specific cross-linkable polyolefin. SOLUTION: This composition is obtained by carrying out the melt mixing of (A) a silane-grafted polymer obtained by reacting a base polymer comprising a medium or low density linear polyethylene having 0.910-0.945 g/cm3 density, 0.5-5 g/10 min melt index, and having <=40% heat strain rate (JIS K 6723) just after the extrusion, with an organic unsaturated silane of the formula RR'SiY2 (R is a monovalent olefinically unsaturated hydrocarbon group; Y is a hydrolyzable organic group; R' is a monovalent hydrocarbon group without an aliphatic unsaturated hydrocarbon, or same as Y) and a free radical-generating agent, substantially in the absence of water, with (B) a carrier polymer A (preferably polyethylene) containing a silanol condensation catalyst and an antioxidant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silane crosslinked resin obtained by reacting a base polymer with an organic unsaturated silane and a free radical generator to form a silane graftmer, and then melt-mixing a carrier polymer A containing a silanol condensation catalyst and the like. Composition, and wire coating with this composition,
The present invention relates to an insulated cable sheathed immediately after coating.

[0002]

2. Description of the Related Art As a simple method for crosslinking polyethylene, chemical crosslinking, electron beam irradiation crosslinking and hot water crosslinking (which proceed using an organic silane compound as a medium) are widely known, and one of them is hot water crosslinking. Has the advantages that the cost of a crosslinking apparatus is much lower than that of chemical crosslinking or electron beam irradiation crosslinking, and that crosslinking can be easily controlled. As a typical example of the hot water cross-linked polyethylene, the polyolefin is subjected to a graft reaction with an organic unsaturated silane in the presence of a free radical generator to perform silane grafting, and then the silane grafter is subjected to a silanol condensation catalyst in the presence of a silanol condensation catalyst. The so-called silane crosslinking method of crosslinking by contact with moisture is generally known. For example, JP-B-48-1711, JP-A-57-
No. 49109 discloses this.

[0003] However, the hot water cross-linking, in which the equipment cost is lower than other cross-linking methods, is missed in that much time and cost are required for the cross-linking treatment.
An electric wire coated with a water-crosslinkable resin composition undergoes a very slow cross-linking reaction at room temperature. Therefore, it is necessary to promote cross-linking in hot water of about 80 ° C. or a high-temperature and high-humidity tank. Even if it is promoted, it takes about one day, and the investment cost of the crosslinking treatment equipment is enormous. For this reason, even if the equipment cost is very low, the advantage will be diminished if a large cost is applied to the crosslinking treatment cost.

[0004] For this reason, various attempts have been made to reduce the time required for the cross-linking treatment of an electric wire extruded with a water-crosslinkable resin. For example, a method is known in which a catalyst or an auxiliary agent is added to a modified silane compound to promote cross-linking, which is disclosed in JP-A-57-208006 and JP-A-62-106.
No. 947. Also, a method of increasing the contact with moisture during the crosslinking of the water-crosslinked resin-coated electric wire and shortening the crosslinking time is known, which is disclosed in JP-A-60-254520 and JP-A-60-26510. .
Further, a method of shortening the time of the crosslinking treatment by promoting the diffusion of water into the inside of the water-crosslinking resin by performing the crosslinking treatment of the water-crosslinking resin-coated electric wire in an ultrasonic atmosphere is disclosed in JP-A-Hei.
It is disclosed by Japanese Patent Publication No. 31241. However, all of the above methods only shorten the time of the crosslinking treatment by hot water or steam treatment, and do not eliminate the water crosslinking step.

In addition, hot water crosslinked polyethylene has a disadvantage that the effect of improving heat resistance and the like is lower than that of chemical crosslinking or electron beam irradiation crosslinking. Therefore, examples of using a linear medium-low-density polyethylene for a base resin in order to effectively improve heat resistance are increasing. However, when a linear medium-low-density polyethylene having a higher melting point and a higher melt viscosity than a low-density polyethylene or the like is used as a base resin, heat is generated in the extruder to cause early crosslinking, or the molding surface becomes rough due to friction with a die. There was a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and provides a silane-crosslinked polyolefin resin composition which is particularly excellent in the smoothness and heat resistance of a molding surface. It is another object of the present invention to provide an insulated cable capable of sheathing an electric wire extrusion-coated with the silane-crosslinked polyolefin resin composition of the present invention immediately after coating.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a polymer of the general formula R under substantially water-free conditions.
R'SiY2 (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, R 'is a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon or the same as Y)
In the silane crosslinked polyolefin resin composition obtained by reacting an organic unsaturated silane represented by and a free radical generator to form a silane graftmer, and then melt-mixing a carrier polymer A containing a silanol condensation catalyst and an antioxidant. , Base polymer having a density of 0.910
0.945g / cm ³ a melt index from 0.5 to 5
This is a silane-crosslinked polyolefin resin composition comprising a linear low-density polyethylene of g / 10 min and having a heat deformation ratio (JIS K 6723) of 40% or less immediately after extrusion.
In a preferred form, the base polymer has a density of 0.9.
The melt index is 0.1 at 10 to 0.945 g / cm ³ .
A melt viscosity of 65 to 5 g / 10 min, which is a linear medium low density polyethylene having a melt viscosity of 65 or more when used alone or in combination of two or more.
0.0015000 poise and a die swell of 1.50 or more (diameter 1 mm, length 1 at 200 ° C.)
(Measured using a 0 mm capillary at a shear rate of 240 sec ^-1 ). More preferably, the base polymer has a melt viscosity of 6500-15000 poise and a die swell of 1.
50 or more (diameter 1mm, length 10m under the condition of 200 ° C)
and a linear in the low density polyethylene 45 and 90 parts by weight of the measurement) at a shear rate of 240 sec ^-1 using a capillary m, linear in the low-density polyethylene from 10 to 55 parts by weight with a melt viscosity of 9,000 to 11,000 poise Wherein the carrier polymer A is selected from the group consisting of polyethylene, polypropylene, and copolymerization of ethylene and α-olefin, and the amount of the carrier polymer A is 2 to 5% by weight.
Further, it is an insulated cable in which an electric wire is coated with these silane crosslinked polyolefin resin compositions, and an insulated cable in which an electric wire is coated and sheathed immediately after coating.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The linear medium-low-density polyethylene used in the base polymer of the present invention refers to a gas-phase method, a solution method, and a suspension method using various catalysts such as a Ziegler-based catalyst and a chromium-based catalyst. It is a copolymer with an α-olefin containing ethylene as a main component by various polymerization methods such as a synthesis method, and has a density of 0.910 to 0.945 g / cm ³ and a melt index of 0.5 to 5 g / 10 min. is there. Examples of the α-olefin include propylene of C3 to C12,
Butene-1, pentene-1, octene-1, 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1, nonene-1, decene-1, undecene-1, dodecene-1 And the like. The density of the linear medium-low density polyethylene used is 0.910 g /
If it is less than ³ cm ³ , the heat resistance is reduced, and 0.945
Exceeding g / cm ³ causes a reduction in extrusion processability.

The melt viscosity of the base polymer of the present invention is 6
500-15000 poise, die swell 1.50
(Measured at a shear rate of 240 sec ^-1 using a capillary having a diameter of 1 mm and a length of 10 mm at 200 ° C.)
Are preferred. The melt viscosity of the base polymer is 65
Less than 00 poise or more than 15,000 poise causes poor appearance. Also, when the die swell is less than 1.50, the appearance is similarly deteriorated. More preferably, the linear medium-low density polyethylene 45 to 6500-10000 poise and the die swell is 1.50 or more.
It is a base polymer comprising a mixture of 90 parts by weight and 10 to 55 parts by weight of a linear medium and low density polyethylene having 9000 to 11,000 poise. Melt viscosity is 9000-1
When the addition amount of the linear low-density polyethylene of 1,000 poise is less than 10 parts by weight, the effect of improving heat resistance is reduced. On the other hand, if it exceeds 55 parts by weight, the extrusion processability is reduced.

[0010] The organic unsaturated silane of the present invention is grafted to the base resin so as to be a cross-linking point between the base resins. The organic unsaturated silane used in the present invention is represented by the general formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R 'is an aliphatic unsaturated hydrocarbon group. Monovalent hydrocarbon groups other than hydrogen or
The same compound as used for Y) is used. It is desirable to use an organic unsaturated silane represented by the general formula RSiY _{3 in} which R ′ is the same as Y, for example, vinyltrimethoxysilane,
Vinyl triethoxy silane, vinyl tributoxy silane, allyl trimethoxy silane, allyl triethoxy silane and the like can be mentioned. The amount of these additives is from 0.1 to 5% by weight, preferably from 0.7 to 3% by weight, based on the total weight of the polymer. If the amount is less than 0.1% by weight, sufficient grafting does not occur, and if the amount exceeds 5% by weight, molding failure occurs and it is not economical.

[0011] The free radical generator of the present invention functions as an initiator of the silane grafting reaction. The free radical generator used in the present invention includes various organic peroxides and peresters having a strong polymerization initiating action, such as dicumyl peroxide, α, α′-bis (t-butylperoxydiisopropyl) benzene, Di-t-butyl peroxide, t-butylcumyl peroxide, di-benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypivalate, t -Butylperoxy-2-ethylhexanoate; The amount of these additives is 0.01 to 0.5% by weight, preferably 0.05 to 0.2% by weight, based on the total weight of the polymer. 0.0
If the amount is less than 1% by weight, a sufficient silane grafting reaction does not proceed.

The carrier polymer A can be added by kneading and granulating a silanol condensation catalyst and an antioxidant with the carrier polymer A of the present invention. The carrier polymer A must also be in a particulate form and a solid compatible with the base polymer to be crosslinked. The carrier polymer A of the present invention is usually in the form of granules or granules in the form of pellets, and the preferred form is pellets. As the carrier polymer A used in the present invention, for example, polyethylene, polypropylene, a copolymer of ethylene and an α-olefin, and as the α-olefin, C3-C12 such as propylene, butene-1, pentene-1, octene-1 , 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1, nonene-1, decene-1, undecene
1, dodecene-1 and the like, and mixtures thereof.

The silanol condensation catalyst of the present invention includes dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate, lead naphthenate, zinc caprylate, cobalt naphthenate, tetrabutyl titanate, and stearic acid. Organic metal compounds such as lead, zinc stearate, cadmium stearate, barium stearate, calcium stearate and the like can be mentioned. These additives may be added in an amount of 0.01 to 0.2% by weight, preferably 0.02 to 0.1% by weight, based on the total weight of the polymer.
% By weight. If the amount is less than 0.01% by weight, a sufficient crosslinking reaction does not proceed. If the amount exceeds 0.2% by weight, crosslinking occurs locally in the extruder at the time of extrusion, and the appearance is significantly deteriorated.

The amount of the carrier polymer A is in the range of 2 to 5% by weight. If the amount is less than 2% by weight, a sufficient crosslinking reaction does not occur. If the amount exceeds 5% by weight, molding failure (scorch or unstable ejection) occurs, and it is not economical. As other additives, if desired, commonly used additives such as antioxidants, neutralizers, ultraviolet absorbers,
Antistatic agent, pigment, dispersant, thickener, metal deterioration inhibitor,
A fungicide, a flow regulator, other inorganic fillers, or the like, or other synthetic resins can be contained.

The crosslinked polyolefin resin composition of the present invention has extremely excellent heat deformation properties and can be used for various applications. If a post-crosslinking treatment step such as steam treatment or hot water treatment after extrusion is performed, the heat resistance is further improved, but this step can be omitted. Therefore, it is particularly suitable for the production of insulated cables that require heat resistance and flexibility, and it is possible to cover the electric wire and then apply a sheath without performing a water crosslinking step. For this purpose, it is necessary that the heating deformation ratio immediately after extrusion is 40% or less.

[0016]

The following examples illustrate the invention, but are by way of example only and the invention is not limited thereto. An example will be described below. << Production of Carrier Polymer A >> The carrier polymer A, a silanol condensation catalyst, an antioxidant and the like were kneaded and granulated according to the compounding ratio shown in Table 1 using a pressure kneader.

<< Production of Silane Graft Mer >> Next, a polyolefin base polymer, an unsaturated organic silane compound and a free radical generator in the proportions shown in Tables 2 and 3 were blended in the ratios shown in Tables 4 and 5, and the silane graft mer was prepared. Manufactured.

The produced graftmer and carrier polymer A were mixed in the ratios shown in Tables 6 to 8, and the tape was extruded using an extruder. The heating deformation rate immediately after extrusion of this extruded tape was evaluated. In addition, the wire was extruded with the same composition as when the tape was extruded, and the smoothness of the molded surface was evaluated. The results are shown in Tables 6 to 8.

The raw materials used are as follows. (1) L-LDPE (1): linear low-density polyethylene (density: 0.924 g / cm ³ , MI; 3.0 g / 10 min) (2) VTMOS: vinyltrimethoxysilane (3) DCP: dicumyl peroxide (4) LDPE: low density polyethylene (density; 0.925 g / c
m ³ , MI; 1.5 g / 10 min) (5) PP: polypropylene (homopolymer, MI (230 ゜)
C); 2.0 g / 10 min) (6) DBTDL: dibutyltin dilaurate (7) Antioxidant: phenolic antioxidant / Irganox 1010 (manufactured by Ciba Geigy) (8) Lubricant: low molecular weight polyethylene / sun wax 171
P (manufactured by Sanyo Chemical Industries, Ltd.) (9) L-LDPE (2): linear medium-low density polyethylene (density: 0.917 g / cm ³ , MI; 0.7 g / 10 min) (10) L-LDPE ( 3): Linear medium-low density polyethylene (density; 0.919 g / cm ³ , MI; 2 g / 10 min) (11) L-LDP
E (4): Linear medium-low-density polyethylene (density: 0.920 g)
/ cm ³ , MI; 2 g / 10 min) (12) L-LDPE (5): linear medium-low density polyethylene (density: 0.920 g / cm ³ , MI; 4 g / 10 min) (13) L-LDPE (6) ): Linear medium-low-density polyethylene (density: 0.925 g / cm ³ , MI: 1.7 g / 10 min) (14) L-LDPE (7): Linear medium-low-density polyethylene (density: 0.924 g / cm ³⁾ , MI; 1 g / 10 min) (15) L-LDPE (8): linear medium-low density polyethylene (density; 0.920 g / cm ³ , MI; 1 g / 10 min)

The evaluation method is as follows. (16) Measurement of Melt Viscosity and Die Swell by Capillograph The melt viscosity and die swell were measured using a Capillograph made by Toyo Seiki. The measurement was performed at 200 ° C., and the measured range was a shear rate of 20 to 6000 sec ⁻¹ , and the numerical values in the text and the table are those at 240 sec ⁻¹ . (17) Appearance of tape extrusion (confirmation of presence or absence of bumps): Extruder of 50mmφ 130-160-180-190-180 ℃ L / D: 20 Compression ratio 3.5 Tape die: width 100mm Lip interval 1mmt Screw rotation speed 40rpm Tape appearance (Bugs) Evaluation: The order of △>△> × was given, and the level of ○ was judged to be acceptable. (18) Heat deformation ratio (%): JIS K 6723
by. (19) Coated wire extrusion appearance (Evaluation of molding surface): Extruder with 50mmφ 130-160-180-190-180 ℃ L / D: 24 Compression ratio 4.0 Conductor diameter 0.8mmφ Coating thickness 1.00mmφ Screw speed 40 rpm Coating Appearance evaluation of the electric wire: ○>△> ×, in order, and the level of “O” was accepted.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

[Table 7]

[0028]

[Table 8]

As is clear from the table, Examples 1 to 3 have good extrusion processability and smoothness of the molding surface, and show extremely excellent heat resistance. That is, the heat deformation ratio is 40% or less immediately after the extrusion, and the crosslinking treatment step can be omitted. On the other hand, all of the comparative examples have difficulty in smoothness, and the extrusion processability and heat resistance are not balanced.

[0030]

According to the present invention, it is possible to obtain a silane-crosslinked polyolefin having excellent molding surface smoothness and excellent heat resistance. Hanging can be performed. As a result, not only is the productivity of the product significantly improved, but also the production cost is greatly reduced, which greatly contributes to the production of the insulated cable.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 123/26 C09D 123/26 151/06 151/06 183/10 183/10 F-term (Reference) 4J002 BB031 BB032 BB052 BB122 EG038 EG048 EG078 EJ029 EK037 EK047 EK057 EK067 EX016 EX036 EZ048 FD079 FD148 4J026 AA11 AA12 AA13 AA14 AC17 AC18 AC36 BA43 DA17 DB15 GA08 GA09 4J004 CB03 JA03 CB03 JA02 PA20 PB09 PC02 5G305 AA02 AB24 AB40 BA11 BA22 BA26 CA01 CA40 CA53 CA54 DA23

Claims (7)

[Claims] 1. A compound of the general formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, R ' Is reacted with an organic unsaturated silane represented by a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon or the same as Y) and a free radical generator to form a silane graftmer, and then a silanol condensation catalyst and an oxidation catalyst. In a silane-crosslinked polyolefin resin composition obtained by melt-mixing a carrier polymer A containing an inhibitor, a base polymer having a density of 0.910 to 0.945 g / cm ³ and a melt index of 0.5 to 5 g / 10 min. A silane-crosslinked polyolefin resin comprising a chain medium-low-density polyethylene and having a heat deformation ratio (JIS K 6723) of 40% or less immediately after extrusion. Composition. 2. The base polymer having a density of 0.910
0.945g / cm ³ a melt index from 0.5 to 5
g / 10 min linear low-density polyethylene having a melt viscosity of 6500 to 1 when used alone or in combination of two or more.
The silane-crosslinked polyolefin resin according to claim 1, which has a 5,000 poise and a die swell of 1.50 or more (measured at a shear rate of 240 sec- ¹ using a capillary of 1 mm in diameter and 10 mm in length at 200 ° C). Composition. 3. The base polymer has a melt viscosity of 6500.
A linear medium low-density polyethylene having a die swell of ダ イ 15,000 poise and a die swell of 1.50 or more (measured at a shear rate of 240 sec ⁻¹ using a capillary of 1 mm in diameter and 10 mm in length at 200 ° C.) 2. The silane-crosslinked polyolefin resin composition according to claim 1, comprising a mixture of 1 part by weight and 10 to 55 parts by weight of a linear medium-low-density polyethylene having a melt viscosity of 9000 to 11,000 poise. 4. The carrier polymer A is polyethylene,
4. The silane-crosslinked polyolefin resin composition according to claim 1, wherein the composition is selected from the group consisting of polypropylene and copolymerization of ethylene and α-olefin. 5. The silane-crosslinked polyolefin resin composition according to claim 1, wherein the amount of the carrier polymer A is 2 to 5% by weight. 6. An insulated cable obtained by coating an electric wire with the silane-crosslinked polyolefin resin composition according to claim 1. 7. An insulated cable, wherein an electric wire is coated with the silane-crosslinked polyolefin resin composition according to claim 1 and sheathed immediately after coating.