KR101131132B1 - Coaxial cable - Google Patents

Abstract

An insulator layer coated on an inner conductor in a coaxial cable provides sufficient inner pressure resistance and provides a high frequency coaxial cable having a low attenuation during transmission. By foaming a resin composition comprising a cyclic olefin resin, a high density polyethylene, and a low density polyethylene and / or a linear low density polyethylene, an insulating layer having a higher foaming degree and excellent mechanical strength than a conventional insulating layer can be formed. As a result, the insulator layer formed on the inner conductor of the coaxial cable has a low dielectric loss tangent and a low dielectric constant, thereby providing a high frequency coaxial cable having excellent transmission characteristics and mechanical characteristics.

Description

Coaxial Cables {COAXIAL CABLE}

The present invention relates to a coaxial cable using a cyclic olefin resin.

Recently, the demand for broadband communication such as mobile phones, the Internet, and wireless LANs is increasing. In order to transmit information at a higher speed and in a large amount, high frequency of electric signals is proceeding remarkably. For this reason, a coaxial cable with a small amount of attenuation in the high frequency band and a low signal delay is required.

The coaxial cable is mainly composed of a center conductor, an insulator layer provided thereon, and an outer conductor provided on its outer circumference. Since the amount of attenuation in the high frequency band is important, it is most effective to reduce the dielectric loss tangent of the insulator layer to realize the high frequency coaxial cable. In addition, it is effective to make it foam in order to reduce further. However, by foaming, the internal pressure resistance of the insulating layer is lowered, which may cause a problem that it is difficult to maintain the shape of the foam.

In order to reduce the dielectric constant of the insulating layer, it is known that increasing the foaming degree of the insulating layer is effective. Moreover, cyclic olefin resin is mentioned as an insulating material with a small dielectric loss tangent. Cyclic olefin resins are also expected to have excellent foam formability and excellent properties of inner pressure resulting from high rigidity.

Patent Document 1 discloses a high frequency coaxial cable using norbornene resin. In addition, Patent Document 2 discloses an insulating material having excellent internal pressure resistance by blending a cyclic olefin-ethylene copolymer with a polyolefin.

1. Japanese Patent Laid-Open No. 2000-297172 2. Japanese Patent Publication No. 2000-311519

However, a coaxial cable having a smaller attenuation amount is required in the high frequency band, and an improvement to be a higher performance coaxial cable than the coaxial cables of Patent Documents 1 and 2 is required. As can be seen from the examples of Patent Documents 1 and 2, the foaming degree of the insulator layer is about 62% in the former and about 72% in the latter. Accordingly, in order to realize a coaxial cable having a smaller attenuation in the high frequency band, a method of improving the foaming degree of the insulator layer can be considered. However, in general, when the degree of foaming is increased, the inner pressure is deteriorated due to expansion of the foaming cell. In addition, when the foam cell breaks due to expansion, an insulating layer having a low dielectric constant cannot be obtained. For this reason, there is a need for a coaxial cable having internal pressure resistance that can maintain the independence of the foaming cell even if the degree of foaming is increased and can be sufficiently used as a coaxial cable.

This invention is made | formed in order to solve the above subjects, The objective is to provide the coaxial cable which has the inside pressure resistance which an insulator layer can fully use as a coaxial cable, and whose foaming degree of an insulator layer is higher.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched in order to solve the said subject. As a result, the inventors have found that the above problems can be solved by foaming a resin composition containing a cyclic olefin resin, a high density polyethylene, a low density polyethylene and / or a linear low density polyethylene, and have completed the present invention. More specifically, the present invention provides the following.

(1) A foamed molding layer of a resin composition comprising a cyclic olefin resin, high density polyethylene, low density polyethylene and / or linear low density polyethylene is provided as an insulating layer, and the foaming degree of the insulating layer is 80% to 90%. Coaxial cable which is%.

According to the invention of (1), the insulating layer in the coaxial cable of the present invention contains a cyclic olefin resin. The cyclic olefin resin has a low dielectric loss tangent, a low dielectric constant and good foamability formation, and further has a high modulus of elasticity, whereby the inner pressure resistance of the foamed molded article is expected to be improved. Therefore, since the insulating layer in the coaxial cable of this invention has such a characteristic, the coaxial cable of this invention can be used suitably for high frequency. On the other hand, cyclic olefin resin has the disadvantage that it is inflexible. However, the insulating layer in the coaxial cable of the present invention contains low density polyethylene and / or linear low density polyethylene having excellent flexibility. For this reason, the fault of the cyclic olefin resin can be compensated for, and the insulating layer excellent in flexibility can be made.

Moreover, since low density polyethylene etc. also have favorable foamability formation, it is preferable to contain even in the point which raises the foaming degree of an insulating layer. However, low density polyethylene and / or linear low density polyethylene have the drawback that the dielectric loss tangent is relatively high. However, the insulating layer in the coaxial cable of the present invention contains high density polyethylene. Since the high density polyethylene is a low dielectric loss tangent, it is possible to complement the high dielectric loss tangent which is a disadvantage of the low density polyethylene together with the cyclic olefin resin.

The high-density polyethylene also has a drawback of poor foamability, but the shortcomings can be compensated for by cyclic olefin resins, low-density polyethylene, and / or linear low-density polyethylene. By utilizing the advantages of the three or four components, a coaxial cable suitable for high frequency can be obtained.

Foam degree shows the grade of the bubble contained in an insulating layer. If there are many bubbles, the ratio of the gas with low dielectric constant in an insulating layer will increase. Therefore, the higher the foaming degree, the lower the dielectric loss tangent and the dielectric constant of the insulating layer in the coaxial cable, so that a coaxial cable having a small attenuation amount can be obtained even at a high frequency. The insulating layer of the coaxial cable of the present invention can realize a higher foaming degree than in the prior art. This is because it depends on the good inner pressure of the cyclic olefin resin and the good foaming properties of the cyclic olefin resin and the low density polyethylene and / or the linear low density polyethylene. This is because if foamability is good, the foaming cells may exist independently even if the degree of foaming is increased. The foaming degree in this specification means the foaming degree calculated | required by following formula (1).

(2) The said resin composition contains 15 mass%-30 mass% of the said cyclic olefin resin, and 70 mass%-85 mass% in the total amount of the said high density polyethylene, the said low density polyethylene, and / or linear low density polyethylene (1) The coaxial cable described in

According to the invention of (2), since the content of the cyclic olefin resin contained in the insulating layer in the coaxial cable is in the above range, the effects such as good foamability, low dielectric constant and inner pressure resistance of the cyclic olefin resin can be sufficiently obtained. Can be exercised. In addition, by the content of cyclic olefin resin in the said range, the fault that it is slightly inflexible can be fully compensated with polyethylene. For this reason, by using the said insulating layer for a coaxial cable, the coaxial cable more suitable for high frequency can be obtained.

(3) The coaxial cable as described in (2) containing 20 mass%-40 mass% in the total amount of the said low density polyethylene and / or linear low density polyethylene.

According to the invention of (3), when the total amount of the low density polyethylene and / or the linear low density polyethylene contained in the insulating layer in the coaxial cable is in the above range, the effect of excellent flexibility of the polyethylene is sufficiently exhibited, and the dielectric constant is The high defect can be sufficiently compensated by high density polyethylene and cyclic olefin resin. For this reason, a coaxial cable more suitable for high frequency can be obtained.

(4) The coaxial cable according to any one of (1) to (3), wherein the compressive strength of the insulating layer is 800 N / cm ² or more and the attenuation amount is 24 dB / 100 m or less.

According to the invention of (4), by increasing the foaming degree of the insulating layer in the coaxial cable to increase the voids in the insulating layer, the compressive strength is 800 even if the dielectric constant of the insulating layer is lowered and the attenuation amount is 24 dB / 100 m or less. Since N / cm <^2> or more, the coaxial cable excellent in mechanical strength can be obtained. In addition, the insulating layer in the coaxial cable of the present invention comprises low density polyethylene and / or linear low density polyethylene. For this reason, since all the other materials of a coaxial cable are excellent in flexibility, the flexibility of an insulating layer becomes excellent, and also the coaxial cable becomes excellent also in the whole coaxial cable, and becomes a more preferable coaxial cable.

Compressive strength refers to the maximum stress that a material can withstand against a compressive load and is one of the indicators of the inner pressure of the insulating layer of a coaxial cable. Since the insulating layer having a low compressive strength is broken by the force applied to the coaxial cable during use, etc., it is not preferable as the insulating layer of the high frequency coaxial cable. Since the insulating layer used in the present invention has a compressive strength of 800 N / cm ² or more, it can be suitably used as an insulating layer for coaxial cables.

It is preferable that the compressive strength of the insulating layer in the coaxial cable of this invention is 800 N / cm <^2> or more. If it is 800 N / cm <^2> or more, since it has sufficient mechanical strength, it can use suitably as an insulating layer for coaxial cables.

It is preferable that the insulation layer in the coaxial cable of this invention is 24 dB / 100m or less. If the amount of attenuation is 24 dB / 100 m or more, the transmission loss increases, which may impair normal operation of the electronic device or the like.

In general, large dielectric loss results in high frequency attenuation. In particular, the dielectric loss tangent has a great effect on the attenuation in the high frequency band. For this reason, in order to reduce the attenuation amount of the coaxial cable in the high frequency band, the dielectric loss tangent of the insulating layer must be small.

(5) The coaxial cable according to any one of (1) to (4), wherein the moisture permeation amount of the insulating layer is 0.55 g / m ² ? Day? Atm or less.

According to the invention of (5), the insulating layer in the coaxial cable of the present invention is more suitable for high frequency because it hardly transmits water molecules of high dielectric constant which cause an increase in attenuation amount. In addition, moisture can penetrate the insulating layer to prevent the internal conductor from corroding. For this reason, a coaxial cable which can be used for a long time can be obtained.

It is preferable that the moisture transmittance of the insulating layer used for the coaxial cable of this invention is 0.55 g / m <^2> day * atm or less. If it exceeds 0.55 g / m ² ? Atm, moisture tends to adhere, and in severe cases, corrosion may occur, resulting in poor conduction.

(6) The coaxial cable according to any one of (1) to (5), wherein the insulation layer has a relative dielectric constant of 1.20 or less in the frequency range of 1 GHz to 10 GHz.

According to the invention (6), by reducing the dielectric constant of the dielectric material dielectric material used in the coaxial cable of the present invention, the signal delay time is reduced in the transmission in the coaxial cable, and the coaxial cable capable of coping with high speed and high capacity of communication Can be obtained.

The dielectric layer in the coaxial cable of the present invention preferably has a relative dielectric constant of 1.2 or less in the frequency range of 1 GHz to 10 GHz. If the relative dielectric constant in the frequency domain is 1.2 or less, the signal delay is small, which is preferable.

(7) The coaxial cable according to any one of (1) to (6), wherein the cyclic olefin resin is a copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof.

According to the invention of (7), since the cyclic olefin resin has the above composition, there is an effect that the balance of signal transmission characteristics, flexibility, compressive strength, moisture permeation characteristics, etc. as a coaxial cable is excellent.

(8) The cyclic olefin resins (1) to (7) having a relative dielectric constant of 2.3 or less in the frequency range of 1 GHz to 10 GHz, a dielectric loss tangent of 4 × 10 ^-4 or less, and a flexural modulus of 2.0 GPa or more at room temperature. ) The coaxial cable according to any one of).

According to the invention of (8), the dielectric loss tangent of the cyclic olefin resin contained in the insulating layer in the coaxial cable of the present invention is low, and by using this cyclic olefin resin, an insulating layer having a low dielectric loss tangent can be produced. If the dielectric loss tangent of the insulating layer is low, the attenuation amount of the coaxial cable is small. For this reason, this coaxial cable with a low dielectric loss tangent is suitable for high frequency use.

In addition, by using a cyclic olefin resin having a small relative dielectric constant, a signal delay time is shortened and excellent characteristics can be obtained as a high frequency coaxial cable.

Flexural modulus refers to the deformation resistance of a material with respect to bending stress. A material having a high flexural modulus is preferable because of its excellent resistance to bending stress and mechanical strength. Flexural stress in this specification is the flexural modulus measured based on ISO178. The insulating layer of the coaxial cable of the present invention contains a material having flexibility such as low density polyethylene. This can prevent the material from becoming brittle.

It is preferable that the bending elastic modulus of cyclic olefin resin is 2 GPa or more, More preferably, they are 2 GPa or more and 3.5 GPa or less. If the flexural modulus is less than 2 GPa, the medial pressure is impaired. If the flexural modulus is more than 3.5 GPa, the flexibility is impaired and the blending range is narrowed.

According to the present invention, it is possible to obtain a coaxial cable having an insulation pressure which can be sufficiently used as a coaxial cable and having a higher foaming degree of the insulator layer. Since the foaming degree of the insulating layer in a coaxial cable is high, the dielectric loss tangent and dielectric constant of an insulating layer will become low, and it can use it suitably for a high frequency coaxial cable.

1 is a view showing an extrusion apparatus.
2 is a diagram illustrating a coaxial cable manufacturing apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of the coaxial cable of this invention is described in detail, this invention is not limited to the following embodiment, It can implement by changing suitably within the objective range of this invention. Although description may be omitted suitably about the part which overlaps description, it does not limit the summary of invention.

<Cyclic olefin resin>

Hereinafter, the cyclic olefin resin which becomes an essential component of the coaxial cable of this invention is demonstrated. The cyclic olefin resin has properties such as low dielectric loss tangent, low dielectric constant, foamability, low water absorption, and inner pressure resistance, and is therefore preferable as a material included in the insulating layer used for the coaxial cable. The cyclic olefin resin used for this invention contains a cyclic olefin component as a copolymerization component, and will not specifically limit, if it is a polyolefin resin containing a cyclic olefin component in a principal chain. For example

(a1) addition polymer of cyclic olefin or its hydrogenated substance,

(a2) an addition copolymer of cyclic olefin and α-olefin or a hydrogenated product thereof,

(a3) The ring-opening (co) polymer of cyclic olefin or its hydrogenated substance is mentioned.

Moreover, as cyclic olefin resin which contains the cyclic olefin component used for this invention as a copolymerization component,

(a4) The unsaturated compound which has a polar group in resin of said (a1)-(a3) is grafted and / or copolymerized.

Examples of the polar group include a carboxyl group, an acid anhydride group, an epoxy group, an amide group, an ester group and a hydroxyl group. Examples of the unsaturated compound having a polar group include (meth) acrylic acid, maleic acid, maleic anhydride and itaconic anhydride. , Glycidyl (meth) acrylate, (meth) acrylic acid alkyl (C1-C10) ester, alkyl maleic acid (C1-C10) ester, (meth) acrylamide, (meth) acrylic acid-2-hydroxyethyl Etc. can be mentioned.

In this invention, cyclic olefin resin (a1)-(a4) which contains the said cyclic olefin component as a copolymerization component may be single 1 type, and may mix and use 2 or more types. In this invention, the addition copolymer of (a2) cyclic olefin and (alpha) -olefin, or its hydrogenated substance can be used preferably.

Moreover, it is also possible to use commercially available resin as cyclic olefin resin which contains the cyclic olefin component used for this invention as a copolymerization component. Commercially available cyclic olefin resins include, for example, TOPAS (registered trademark) (manufactured by TOPAS Advanced Polymer), Aper (registered trademark) (manufactured by Mitsui Chemicals), Zeonex (registered trademark) (manufactured by Nippon Xeon), Zeo Noah (trademark) (made by Nippon Zeon), Aton (registered trademark) (made by JSR Corporation), etc. are mentioned.

It does not specifically limit as an addition copolymer of (a2) cyclic olefin and (alpha) -olefin used preferably for the composition of this invention. Particularly preferred examples thereof include a copolymer comprising [1] a C2-C20 alpha -olefin component and [2] a cyclic olefin component represented by the following formula (1).

(In formula, R ¹ ~ R ¹² may be the same or different, respectively, selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group, R ⁹ and R ¹⁰ , R ¹¹ and R ¹² are integrally divalent hydrocarbons A group can be formed and R <^9> or R <^10> and R <^11> or R <^12> may form a ring mutually, and n represents 0 or a positive integer, and when n is two or more, R <^5> -R <^8>. May be the same or different among each repeating unit.)

[1] C2-C20 α-olefin component

The C2-C20 alpha olefin which becomes a copolymerization component of the addition polymer of the cyclic olefin component and other copolymerization components, such as ethylene, used preferably for this invention is not specifically limited. For example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1- Pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. are mentioned. These α-olefin components may be used alone or in combination of two or more thereof. Of these, ethylene alone is most preferred.

[2] Cyclic olefin component represented by Formula 1]

The cyclic olefin component represented by General formula (1) which becomes a copolymerization component in the addition polymer of the cyclic olefin component used preferably for this invention with other copolymerization components, such as ethylene, is demonstrated.

R ¹ to R ¹² in Formula 1 may be the same or different, respectively, and are selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group.

Specific examples of R ¹ to R ⁸ include, for example, hydrogen atoms; Halogen atoms such as fluorine, chlorine and bromine; Lower alkyl groups, such as a methyl group, an ethyl group, a propyl group, and a butyl group, etc. are mentioned, These may differ, respectively, may differ partially, and all may be the same.

In addition, specific examples of R ⁹ to R ¹² include, for example, hydrogen atoms; Halogen atoms such as fluorine, chlorine and bromine; Alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, hexyl group and stearyl group; Cycloalkyl groups such as cyclohexyl group; Substituted or unsubstituted aromatic hydrocarbon groups such as phenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, naphthyl group and anthryl group; And aralkyl groups in which an aryl group is substituted with a benzyl group, a phenethyl group, and other alkyl groups, and these may be different, partially different, and all may be the same.

Specific examples of the case where R ⁹ and R ¹⁰ or R ¹¹ and R ¹² are integrated to form a divalent hydrocarbon group include alkylidene groups such as ethylidene group, propylidene group and isopropylidene group.

R ⁹ Or R ¹⁰ and R ¹¹ Alternatively, when R ¹² forms a ring with each other, the ring formed may be monocyclic or polycyclic, polycyclic having a crosslink, ring having a double bond, or ring composed of a combination of these rings. Moreover, these rings may have substituents, such as a methyl group.

Specific examples of the cyclic olefin component represented by Formula 1 include bicyclo [2.2.1] hepta-2-ene (common name: norbornene), 5-methyl-bicyclo [2.2.1] hepta-2-ene, 5, 5-dimethyl-bicyclo [2.2.1] hepta-2-ene, 5-ethyl-bicyclo [2.2.1] hepta-2-ene, 5-butyl-bicyclo [2.2.1] hepta-2-ene , 5-ethylidene-bicyclo [2.2.1] hepta-2-ene, 5-hexyl-bicyclo [2.2.1] hepta-2-ene, 5-octyl-bicyclo [2.2.1] hepta-2 -Ene, 5-octadecyl-bicyclo [2.2.1] hepta-2-ene, 5-methylidene-bicyclo [2.2.1] hepta-2-ene, 5-vinyl-bicyclo [2.2.1] Bicyclic cyclic olefins such as hepta-2-ene and 5-propenyl-bicyclo [2.2.1] hepta-2-ene;

Tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.1 ^2,5 ] deca-3-ene; Tricyclo [4.4.0.1 ^2,5 ] undec-3,7-diene or tricyclo [4.4.0.1 ^2,5 ] undec-3,8-diene or partial hydrogen adducts thereof (or cyclopentadiene and cyclo Adduct of hexene) tricyclo [4.4.0.1 ^2,5 ] undec-3-ene; 5-cyclopentyl-bicyclo [2.2.1] hepta-2-ene, 5-cyclohexyl-bicyclo [2.2.1] hepta-2-ene, 5-cyclohexenylbicyclo [2.2.1] hepta- Tricyclic cyclic olefins such as 2-ene and 5-phenyl-bicyclo [2.2.1] hepta-2-ene;

Tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene (also called tetracyclododecene), 8-methyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dode Car-3-ene, 8-ethyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene, 8-methylidenetetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] Dodeca-3-ene, 8-ethylidenetetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene, 8-vinyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10 Cyclic olefins such as] dodeca-3-ene and 8-propenyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene;

8-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca- 3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] dodeca-3-ene; Tetracyclo [7.4.1 ^3,6 .0 ^1,9 .0 ^2,7 ] tetradeca-4,9,11,13-tetraene (1,4-methano-1,4,4a, 9a-tetra Also called hydrofluorene), tetracyclo [8.4.1 ^4,7 .0 ^1,10 .0 ^3,8 ] pentadeca-5,10,12,14-tetraene (1,4-methano-1, 4,4a, 5,10,10a-hexahydroanthracene); ^Pentacyclo [6.6.1.1 ^3,6 .0 ^2,7 .0 ^9,14 ] -4-hexadecene, pentacyclo [6.5.1.1 ^{3,6 2} .0 ^9,13 ] -4-penta decene, 4-decene, penta-cyclo penta ^{[7.4.0.0 2,7 .1 3,6 .1 10,13]} ; Cyclo hepta ^{[8.7.0.1 2,9 .1 4,7 .1 11,17 .0} 3,8 .0 12,16] -5- eicosene, heptacyclo cyclo [8.7.0.1 ^2,9 .0 ^3,8 .1 ^4,7 .0 ^12,17 .1 ^{13, l6} ] -14-eicosene; Polycyclic cyclic olefins, such as a tetramer of cyclopentadiene, are mentioned.

These cyclic olefin components can also be used individually by 1 type and in combination of 2 or more type. Among these, bicyclo [2.2.1] hepta-2-ene (common name: norbornene) and tetracyclododecene are preferably used.

[1] The polymerization method of the α-olefin component having 2 to 20 carbon atoms and the cyclic olefin component represented by [2] Formula 1 and the hydrogenation method of the obtained polymer are not particularly limited and can be carried out according to a known method. . Although random copolymerization may be sufficient as block copolymerization, it is preferable that it is random copolymerization.

The polymerization catalyst to be used is also not particularly limited, and can be obtained according to a known method using conventionally known catalysts such as Ziegler-Natta, metathesis-based and metallocene-based catalysts. It is preferable that the addition copolymer of cyclic olefin and (alpha) -olefin used preferably for this invention, or its hydrogenated substance is manufactured using a metallocene type catalyst or a Ziegler-Natta type catalyst.

As the metathesis catalyst, a molybdenum or tungsten-based metathesis catalyst (for example, described in JP-A 58-127728, JP-A 58-129013, etc.) known as a catalyst for ring-opening polymerization of cycloolefins is used. Can be mentioned. In addition, the polymer obtained by the metathesis catalyst is hydrogenated at least 90% of the double bond of the main chain and at least 98% of the carbon-carbon double bond in the aromatic ring of the side chain using an inorganic carrier-supported transition metal catalyst. desirable.

[Other Copolymerization Components]

The addition copolymers of the (a2) cyclic olefin and the α-olefin which are particularly preferably used in the composition of the present invention include the above [1] α-olefin component having 2 to 20 carbon atoms and the cyclic olefin component represented by [2] In addition, other copolymerizable unsaturated monomer components may be contained as needed in the range which does not impair the objective of this invention.

The unsaturated monomer which can be optionally copolymerized is not particularly limited, and examples thereof include hydrocarbon monomers containing two or more carbon-carbon double bonds in one molecule. Specific examples of the hydrocarbon monomer including two or more carbon-carbon double bonds in one molecule include 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 4-methyl- Chain non-conjugated dienes such as 1,5-hexadiene, 5-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene and 7-methyl-1,6-octadiene; Cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2 -Norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 4,9,5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro Cyclic nonconjugated dienes such as -1H-benzoindene; 2,3-diisopropylidene-5-norbornene; 2-ethylidene-3-isopropylidene-5-norbornene; 2-propenyl-2,2-norbornadiene etc. are mentioned. Among these, 1,4-hexadiene, 1,6-octadiene, and cyclic nonconjugated dienes, in particular, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5- Methylene-2-norbornene, 1,4-hexadiene, 1,6-octadiene are preferred.

It is preferable that content of cyclic polyolefin type resin of an insulating layer is 15 mass%-30 mass%. If it is less than 15 mass%, the signal transmission characteristics, compressive strength, water permeability, etc. as a coaxial cable will fall, and if it exceeds 30 mass%, sufficient flexibility may not be obtained.

<Polyethylene>

The high density polyethylene, the low density polyethylene, and the linear low density polyethylene which become an essential component of the coaxial cable of this invention are demonstrated. Since high density polyethylene has a small dielectric loss tangent, it is preferable as a material used for the insulating layer in a coaxial cable. Since low density polyethylene and linear low density polyethylene have flexibility, it is preferable as a material used for the insulating layer in a coaxial cable.

The high density polyethylene, the low density polyethylene, and the linear low density polyethylene preferably have an MFR of 1.0 to 10.0 g / 10 min, specified in JIS K6922-1, and more preferably 2.0 to 8.0 g / 10 min. If it is lower than 1.0 g / 10min, flexibility can be obtained. However, fluidity may deteriorate and good moldability may not be obtained. If it exceeds 10.0 g / 10min, moldability may be good but flexibility may not be obtained.

It is preferable that content of the sum total of the high density polyethylene, the low density polyethylene, and the linear low density polyethylene in the insulating layer of a coaxial cable is 70 mass%-85 mass%.

In particular, it is preferable that content of the sum total of low density polyethylene and linear low density polyethylene is 20 mass%-40 mass%. If it is less than 20 mass%, sufficient flexibility may not be obtained, and if it exceeds 40 mass%, there is a possibility that the dielectric constant of an insulating layer may not be kept low.

<Other Ingredients>

Other thermoplastic resins, various compounding agents, etc. can be added to the insulating layer in the coaxial cable of this invention as needed in the range which does not impair the characteristic. As another resin, another polyolefin resin, a polystyrene resin, a fluororesin etc. are illustrated, for example. These other resins can be used alone or in combination of two or more. Moreover, when flexibility of a coaxial cable is needed, it is preferable to add an elastomer to cyclic polyolefin type resin. The added elastomer is not particularly limited as long as it does not impair the characteristics such as the amount of attenuation of the coaxial cable. For example, a polyolefin elastomer or a styrene elastomer is preferable. In particular, the polyolefin-based elastomer is preferable in terms of achieving a balance between attenuation and flexibility. In addition, as a compounding agent, stabilizers (antioxidants or antioxidants, heavy metal stabilizers, ultraviolet absorbers, heat stabilizers, etc.), antistatic agents, flame retardants, flame retardant aids, colorants (such as dyes and pigments), lubricants, plasticizers, lubricants, mold release agents, crystals Nucleating agents, anti-dripping agents, crosslinking agents and the like are exemplified. Since the insulating layer of a coaxial cable contacts metals, such as copper, which is a conductor, it is preferable to add a heavy metal stabilizer. Heavy metal stabilizers include salicylic acid derivatives (e.g. ADKSTAB CDA6), hydrazide derivatives (e.g. Irganox MD1024), oxalamide groups (e.g. Naugard XL-1), sulfur-containing phosphite compounds (e.g. For example, although the brand name Hostanox OSP-1) etc. are mentioned, the kind of heavy metal stabilizer will not be specifically limited if the characteristic of a coaxial cable is not impaired. It does not specifically limit also about the addition amount of a heavy metal stabilizer, Usually, the addition amount of 0.3 mass% or less with respect to a resin component is used preferably. Although it does not specifically limit about an addition method, It is more preferable to add beforehand to cyclic polyolefin type resin, a polyethylene resin, another addition resin, etc.

<Coaxial cable>

Although the structure of a coaxial cable is not specifically limited, For example, the coaxial cable which consists of an inner conductor, an insulation layer, an outer conductor, and a sheath is the most common example. In the present specification, the term "having a layer of foamed resin composition as an insulating layer" refers to an insulating layer formed on the inner conductor. A common coaxial cable coats an outer conductor for an electronic shield or the like on its insulating layer, and then sheaths the sheath thereon.

The inner conductor is not particularly limited as long as it has conductivity, and examples thereof include a conductive metal such as copper or a copper alloy. The inner conductor may use a braided wire by combining a plurality of conductive metal wires.

The outer conductor is composed of, for example, a braided conductor made by weaving a plurality of conductor wires into a mesh shape. As a conductor element wire used for an external conductor, a copper wire and a copper alloy are used, for example. In addition to braiding, a method of spiral winding, double winding, or the like of a tape-shaped conductor may be mentioned.

The method for foaming the resin composition in the present invention is not particularly limited as long as the desired degree of foaming can be achieved. Preferred methods of foaming include gas foaming.

Gas foaming refers to a method in which a blowing agent is press-fitted into a melt extruder, and an insulating material is coated on a conductor to foam simultaneously with extrusion. Examples of the blowing agent include inert gases such as nitrogen, argon and carbon dioxide; Gas, such as methane, propane, butane, pentane, hexane, a fluorocarbon, is mentioned. Moreover, foaming adjuvant can be used together. For example, foaming aids, such as urea, a urea-type compound, zinc oxide, and zinc stearate, are mentioned. Foaming agents and foaming aids are not limited to these. In addition, these foaming agents etc. can be used individually or in combination of 2 or more types.

The blowing agent may be mixed with the foamed organic polymer in advance, or may be supplied into the extruder from the blowing agent supply port provided in the barrel of the extruder.

The foaming degree is preferably 80% to 90%. If the foaming degree is less than 80%, the dielectric constant and dielectric loss tangent of the insulating layer may be increased, resulting in insufficient characteristics as a high frequency coaxial cable. If the degree of foaming exceeds 90%, there is a possibility that sufficient mechanical strength of the insulating layer cannot be maintained.

<Method of manufacturing coaxial cable>

The method for producing the coaxial cable of the present invention is not particularly limited and a general method can be used. For example, manufacture of a coaxial cable by an extruder is mentioned. The type of extruder may be, for example, a twin screw extruder, a single screw extruder, or a combination thereof to impart a gas injection and coating function.

In the production of coaxial cables, for example, extrusion foaming is carried out on an inner conductor using a blowing agent in an extruder to coat and form a foam insulation layer on the outer circumference of the inner conductor. When coating a foam insulation layer on an inner conductor, coating apparatuses, such as a crosshead die, are used normally. Even if the introduction of the inner conductor into the sheathing device is made in air, it can be manufactured conventionally without compromising the characteristics of the coaxial cable. In the case of coaxial cable manufacture with a very low damping amount, devising a coating device such as filling the inner conductor introduction portion with an inert gas such as nitrogen can suppress oxidation of the resin component by air, which may be preferable for the purpose of stabilizing properties. . The outer conductor is coated on the foam insulation layer in a conventional manner, and finally, the sheath is formed on the outer conductor in a conventional manner.

(Example)

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to these Examples.

<Various materials>

[Cyclic olefin resin]

TOPAS ADVANCED POLYMER company, brand name: TOPAS8007F-04, TOPAS6013S-04, TOPAS6015S-04

Nippon Zeon, brand name: ZEONOR 1060R

The elasticity modulus, specific gravity, dielectric constant, and dielectric loss tangent of the cyclic olefin resin were measured. Elastic modulus was measured based on ISO178. Dielectric properties (dielectric constant, dielectric loss tangent) were measured using the Agilent Network Analyzer 8757D and Kanto Electronics Co., Ltd. complex resonator measuring device, and the relative dielectric constants at 1 GHz, 3 GHz, and 10 GHz were determined by the cavity resonator perturbation method. Was measured at 23 ° C. At the time of measurement, the insulating layer was inserted into the cavity resonator in a predetermined shape (φ 2.5 mm, length 80 mm). Table 1 shows the results of each measurement.

From Table 1, it was confirmed that the cyclic olefin had sufficient inner pressure and adequate flexibility because the elastic modulus was in the range of 2.0 GPa or more and 3.5 GPa or less. In addition, since the dielectric constant is 2.3 or less and the dielectric tangent is 4 × 10 ^-4 or less, the dielectric constant of the insulating layer after foaming can be prevented from increasing due to the dielectric constant of the material portion.

[Polyethylene]

High density polyethylene; Tosoh Corporation make, brand name: Nippon Hard 4040 MFR 5.5 g / 10 min (JIS K6922-1)

Low density polyethylene; Sumitomo Chemical Co., Ltd. make, brand name: Sumikasen G401, MFR 4.0 g / 10min (JIS K6922-1)

Linear low density polyethylene; Sumitomo Chemical Co., Ltd. make, brand name: Sumikasen L GA401 MFR 3.0 g / 10min (JIS K6922-1)

<Measurement and Evaluation Method>

The foaming degree, compressive strength, moisture permeability, relative dielectric constant, and attenuation amount were measured with the resin mixture shown in Table 2 below.

[Measurement of Foam Degree]

The degree of foaming was measured by specific gravity at the stage of manufacture of the coaxial cable described below. The resin density before foaming and the density of the foam were measured and measured using the above equation (1).

[Compressive strength]

The resin composition shown in Table 2 was blended, and the sheet | seat foamed with nitrogen gas was extrusion-molded using the extrusion apparatus (FIG. 1) which set the temperature of cylinder C to 200 degreeC, and the temperature of die D to 195 degreeC. . The blended composition was introduced from the hopper A, and nitrogen gas was injected from the mixing portion B at the center of the cylinder. The sheet thickness was molded to be 5 mm.

The obtained 5 mm thick sheet was cut into 30 mm x 100 mm, and the compressive strength was measured by applying a load in the thickness direction. The measurement was carried out at a test speed of 1 mm / min using Tenshiron UTA-50KN manufactured by Orient Tech.

[Measurement of Water Permeation]

According to ISO 10156-1 (differential pressure method), the measurement was carried out using a VAC-V2 differential pressure gas infiltration apparatus manufactured by Labthink.

[Production method of coaxial cable]

The foam insulation layer was formed in the inner conductor (copper wire) using the coaxial cable manufacturing apparatus shown in FIG. First, the inner conductor insertion hole of the crosshead die 7 on the conductor heater 6 side is closed, and resin is introduced into the hopper 3 of the first extruder by the resin mixture shown in Table 2, and the foaming agent pressure is melted and kneaded with the resin. Nitrogen gas was injected from the inlet 4 and the mixture was injected into the second extruder 2. The mixture further melt kneaded in the second extruder 2 was injected into the crosshead die 7, and a foam insulator containing no inner conductor was obtained through the chiller 8 and the drawer 9. The density of this foam insulator was measured, and the pressure of nitrogen gas was adjusted so that foaming degree might be predetermined, and foaming conditions of the foam insulator were determined. The set temperature of the 1st extruder 1 and the 2nd extruder 2 is 200 degreeC in the case of the resin compound containing TOPAS8007F-04 and ZEONOR 1060R, and in the case of a comparative example, and in the case of the resin compound containing TOPAS6013S-04, It was set to 215 degreeC and 230 degreeC in the case of the resin mixture containing TOPAS6015S-04, respectively. The foaming degree can be set to 80% to 90% of the foaming degree, except for Comparative Example 1 using high-density polyethylene single body. It was set as. The foamed insulator not containing the inner conductor obtained here was used for measuring the dielectric constant.

Next, the inner conductor insertion hole of the crosshead die 7 on the conductor heater 6 side is opened, and the inner conductor 11 (copper wire) having a diameter of 1.4 mm is taken out of the conductor feeder 5, so that the conductor heater 6, The crosshead die 7, the cooling device 8, and the take-out machine 9 were installed in order. The mixture extruded under the same conditions as the extrusion conditions of the foamed insulator determined above is coated on the inner conductor 11 in the crosshead die 7, and then transferred in the order of the cooling device 8 and the take-out machine 9, and the inner conductor ( The take-out speed | rate was adjusted so that the outer diameter of the electric wire 12 which coat | covered 11) with the foam insulation layer might be 4.8 mm. After the adjustment, the wire 12 was wound up and taken out of the winder. Thereafter, the wire 12 was wrapped with a copper corrugate as an outer conductor, and again wrapped with a sheath of polyethylene to obtain a coaxial cable. The attenuation amount of the obtained coaxial cable was measured. When the inner conductor 11 of the electric wire 12 was removed and the density of the foam insulation layer was measured, it confirmed that it was the same density as the foam insulation made under the same extrusion conditions without covering the inner conductor.

In Table 2, Examples 1 to 14 have a foaming degree in the range of 80% to 90%, compressive strength of 800 (kPa) or more, moisture permeation amount of 0.55 (g / m ² ? Day? Atm) or less, relative dielectric constant It confirmed that this 1.20 or less and attenuation amount were 24 (dB / 100m) or less. Therefore, the coaxial cable of Examples 1-14 is a coaxial cable suitable for high frequency. In contrast, Comparative Example 1, which does not contain a cyclic olefin, has a low foaming degree and thus has a high dielectric constant and, as a result, a large amount of attenuation. Moreover, since the moisture permeation amount was also high, it confirmed that it was not suitable for high frequency use. As in Comparative Example 1, Comparative Examples 2 and 3, which do not contain cyclic olefins, have a foaming degree of 80%, so the relative dielectric constant is low. However, the compressive strength is small and cannot be suitably used as a high frequency coaxial cable.

1: first extruder
2: second extruder
3: hopper
4: blowing agent inlet
5: conductor feeder
6: conductor burner
7: crosshead die
8: chiller
9: drawer
10: winder
11: inner conductor
12: wires

Claims (8)

The insulating layer is provided with the layer which foam-molded the resin composition containing cyclic olefin resin, high density polyethylene, and at least one of low density polyethylene and linear low density polyethylene,
The said resin composition is 15 mass%-30 mass% of the said cyclic olefin resin, The total amount of the said high density polyethylene and at least one of the said low density polyethylene and linear low density polyethylene is 70 mass%-85 mass%,
Coaxial cable, characterized in that the foaming degree of the insulating layer is 80% ~ 90%.
First According to claim,
20 mass%-40 mass% in total amount of the said low density polyethylene and linear low density polyethylene, The coaxial cable characterized by the above-mentioned.
The method according to claim 1 or 2,
Coaxial cable, characterized in that the compressive strength of the insulating layer is 800 N / cm ² or more, the attenuation is 24 dB / 100 m or less. The method of claim 1,
Coaxial cable, characterized in that the moisture transmission amount of the insulating layer is 0.55 g / m ² ~ d or less.
The method of claim 1,
The insulation layer has a relative dielectric constant of less than 1.20 in the frequency range of 1 GHz to 10 GHz.
The method of claim 1,
The said cyclic olefin resin is a copolymer of a cyclic olefin and an alpha olefin, or its hydrogenated substance, The coaxial cable characterized by the above-mentioned. The method of claim 1,
The cyclic olefin resin has a relative dielectric constant of 2.3 or less in the frequency range of 1 GHz to 10 GHz, a dielectric loss tangent of 4 × 10 ^-4 or less, and a flexural modulus at room temperature of 2.0 GPa or more. delete

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