JP6948001B2 - Silanol condensation catalyst-containing composition and silane cross-linked polyethylene - Google Patents

Description

The present invention relates to silanol condensation catalyst-containing compositions. The present invention also relates to a silane cross-linked polyethylene and a molded product obtained by using this silanol condensation catalyst-containing composition.

Silane cross-linked polyethylene is widely used in coating materials such as electric wires and cables, pipes, hoses, tubes and the like.

The silane cross-linked polyethylene is obtained by graft-polymerizing an organic silane compound on polyethylene in the presence of a radical generator, and allowing water to act on the obtained graft polymer in the presence of a silanol condensation catalyst.
Such a reaction with water in the presence of a silanol condensation catalyst is called "silane water cross-linking", and usually, a radical generator is allowed to act on polyethylene as a graft initiator in a molding processing machine such as an extruder. An organic silane compound such as alkoxysilane is graft-copolymerized with polyethylene, and then a cross-linking reaction is caused by allowing water to act on a molded product molded by a molding machine. The cross-linking reaction is caused by the hydrolysis and condensation reaction of the organic silane compound by the action of the silanol condensation catalyst which has been mixed in the molded product in advance or has penetrated from the surface of the molded product.

Conventionally, an organotin compound has been widely used as a silanol condensation catalyst used for obtaining silane cross-linked polyethylene. However, due to concerns about environmental hormones, organotin compounds have recently been required to replace silanol condensation catalysts.

As a silanol condensation catalyst instead of an organotin compound, Patent Document 1 discloses an organic sulfonic acid and its hydrolysis precursor, an organic phosphoric acid and its hydrolysis precursor, and a halogen acid. Patent Document 2 discloses an organometallic compound other than an organotin compound. Patent Document 3 discloses a sulfonic acid compound.

Special Table 2008-533280 JP-A-2002-146150 Special Table 2004-526808 Gazette

According to a detailed study by the present inventor, the silanol condensation catalyst disclosed in Patent Documents 1 to 3 has less concern about environmental load, but the catalytic activity is low, so that the cross-linking reaction proceeds sufficiently particularly in a low temperature environment. I found that I wouldn't.

The present invention has been made in view of the above problems of the prior art. That is, the subject of the present invention is a silanol condensation catalyst-containing composition that exhibits good catalytic performance under any cross-linking treatment condition from low temperature conditions to high temperature conditions and has a low concern about environmental load, and the use thereof. It is an object of the present invention to provide the obtained silane crosslinked polyethylene and a molded product.

The present inventor has found that a silanol condensation catalyst-containing composition containing a specific silanol condensation catalyst and polyethylene can solve the above problems. That is, the gist of the present invention is as follows.

In [1] IR spectrum, a silanol condensation catalyst comprising a compound and a metal having a peak in a wavelength region of 1350～1050Cm ^-1 and / or 1800～1650Cm ^-1, and a polyethylene, and the content of the silanol condensation catalyst A silanol condensation catalyst-containing composition characterized in that the amount is 0.001 to 15 parts by mass with respect to 100 parts by mass of polyethylene.

[2] The silanol condensation catalyst-containing composition according to [1], wherein the silanol condensation catalyst contains a zinc compound.

[3] The silanol condensation according to [1] or [2], which further contains silane-modified polyethylene and contains 0.01 to 30 parts by mass of the polyethylene and the silanol condensation catalyst in total with respect to 100 parts by mass of the silane-modified polyethylene. Catalyst-containing composition.

[4] A silane cross-linked polyethylene which is a cross-linked reaction product of the silanol condensation catalyst-containing composition according to [3].

[5] The molded product of the silane cross-linked polyethylene according to [4].

[6] The molded product according to [5], which is an electric wire covering material, a pipe, a hose, a film, or a sheet.

In the IR spectrum, ^{silanol condensation catalysts containing a compound and a metal having a peak in the wavelength region of 1350 to 150 cm -1} and / or 1800 to 1650 cm ^-1 have high catalytic activity, and according to the present invention, such silanol condensation is performed. By using a catalyst, it is possible to provide a silanol condensation catalyst-containing composition that exhibits good catalytic performance under a wide range of cross-linking conditions from low temperature to high temperature and has a low concern about environmental load. In addition, this silanol condensation catalyst-containing composition can be used to provide high-quality silane cross-linked polyethylene and a molded product.

It is an IR spectrum chart of the silanol condensation catalyst-1 used in Example 1-1. It is an IR spectrum chart of the silanol condensation catalyst-2 used in Comparative Example 1-1.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and carried out without departing from the gist of the present invention. In addition, in this invention, when a numerical value or a physical property value is put before and after using "~", it is used as including the value before and after that.

[Silanol condensation catalyst-containing composition]
Silanol condensation catalyst containing compositions of the present invention, in the IR spectrum, the silanol condensation catalyst comprising a metal compound having a peak in a wavelength region of 1350～1050Cm ^-1 and / or 1800~1650cm ^-1 (hereinafter, "the present invention The silanol condensation catalyst is sometimes referred to as "silanol condensation catalyst") and polyethylene, and the content of the silanol condensation catalyst is 0.001 to 15 parts by mass with respect to 100 parts by mass of polyethylene.

The silanol condensation catalyst of the present invention has the effect of exhibiting high catalytic performance under any cross-linking treatment condition from low temperature conditions to high temperature conditions. The reason why the silanol condensation catalyst of the present invention exerts such an effect is not clear, but it is presumed as follows. In the IR spectrum, ^{compounds with peaks in the wavelength range of 1350 to 150 cm -1} and / or 1800 to 1650 cm ^-1 are bound or coordinated to the metal in the presence of water by forming a complex with the metal. It is considered that this is because the functional group is rapidly changed to an OH group and the catalytic activity of the silanol condensation reaction with high silane-modified polyethylene is high regardless of the cross-linking treatment conditions.
In the IR spectrum of the silanol condensation catalyst of the present invention, the wavelength regions having peaks are preferably 1350 to 150 cm ^-1 and 1800 to 1650 cm ^-1 . Note that there is a peak in the wavelength range, for example, as a typical functional group, the peak derived from C-N in 1250～1020Cm ^-1, a peak derived from C = O in 1750～1700Cm ^-1 is detected Means.

The silanol condensation catalyst-containing composition of the present invention containing polyethylene and a silanol condensation catalyst is usually used as a silanol condensation catalyst master batch. Further, the silanol condensation catalyst-containing composition of the present invention may further contain a silane-modified polyethylene described later, but when the silanol condensation catalyst-containing composition of the present invention contains a silane-modified polyethylene, a silane-modified polyethylene The silanol condensation catalyst master batch containing polyethylene and silanol condensation catalyst, polyethylene as a raw material for silane-modified polyethylene, and unsaturated silane, which will be described later, are not limited to those obtained by melt-kneading polyethylene and silanol condensation catalyst. The silanol condensation catalyst-containing composition of the present invention is also a silanol condensation catalyst-containing composition produced by melt-kneading a compound and a radical generator and simultaneously performing melt-kneading of a silane-modified polyethylene by graft modification and melt-kneading of polyethylene and a silanol condensation catalyst. Included in catalyst-containing compositions.

[polyethylene]
The type of polyethylene used in the silanol condensation catalyst-containing composition of the present invention is not particularly limited as long as it contains 50% by mass or more of ethylene units. However, this polyethylene does not contain the silane-modified polyethylene described later, and is used separately from this.

Specific examples of the type of polyethylene include ethylene homopolymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE); ethylene-propylene copolymer, ethylene-propylene. 1-butene copolymer, ethylene / 1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer, ethylene / α-olefin such as ethylene / propylene / butene copolymer Any of such as a polymer can be used. Further, one of these may be used, or two or more thereof may be used in combination.

The melt flow rate (MFR) of polyethylene used in the present invention is not particularly limited, but is usually 0.1 g / 10 minutes or more, preferably 0.5 g / 10 minutes or more, and more preferably 1 g / 10 minutes or more. On the other hand, it is usually 50 g / 10 minutes or less, preferably 40 g / 10 minutes or less, more preferably 30 g / 10 minutes or less, still more preferably 20 g / 10 minutes or less, and particularly preferably 10 g. / 10 minutes or less. When the MFR of polyethylene is in the above range, it is preferable from the viewpoint of moldability of the silane crosslinked polyethylene. In the present invention, the MFR of polyethylene is a value measured at a temperature of 190 ° C. and a load of 21.2 N based on ISO 1133.

The density of polyethylene used in the present invention (JIS K6760) is usually 0.850 to 0.970 g / cm ³ , preferably 0.855 to 0.965 g / cm ³ .

By using a composition satisfying the above MFR and density to prepare the silanol condensation catalyst and the silanol condensation catalyst-containing composition used in the present invention, the silanol condensation catalyst-containing composition which is easy to handle and can be easily produced is made into a silane-modified polyethylene. It has the advantage of being uniformly mixed and dispersed.

Commercially available polyethylene can be used. For example, Japan Polyethylene Corporation, trade name Novatec (registered trademark) HD HJ360, HY430, HY540, LD400, LD400P, Asahi Kasei Chemicals Co., Ltd., trade name Cleolex (registered trademark) K4125, K4750 and the like can be mentioned.

[Silanol condensation catalyst]
Silanol condensation catalysts of the present invention, in the IR spectrum, is intended to include a metal compound having a peak in a wavelength region of 1350～1050Cm ^-1 and / or 1800~1650cm ^-1. In the silanol condensation catalyst-containing composition of the present invention, this silanol condensation catalyst acts as a catalytic component in the silanol condensation reaction when obtaining silane cross-linked polyethylene.

In the IR spectrum, ^{compounds having a peak in the wavelength region of 1350 to 150 cm -1} include amine compounds, carbonyl compounds, carboxylic acids, and esters.

Examples of the amine compound include an alkylamine compound, an alkyldiamine compound, an alkyltriamine compound, an arylamine compound, an aryldiamine compound, and an aryltriamine compound. The alkyl group and aryl group of these amine compounds may have a substituent. Further, when the amine compound has a plurality of alkyl groups and / or aryl groups, they may all be the same or different.

The alkyl group of the amine compound includes methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group and sec-pentyl group. , Tert-Pentyl group, neopentyl group, 1-methylpentyl group, n-hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, neohexyl group, 2-ethylhexyl group, n-heptyl group, isoheptyl group, sec -Heptyl group, tert-heptyl group, neoheptyl group, n-octyl group, isooctyl group, sec-octyl group, tert-octyl group, neooctyl group, n-nonyl group, isononyl group, sec-nonyl group, tert-nonyl group. , Neononyl group, n-decyl group, isodecyl group, sec-decyl group, tert-decyl group, neodecyl group, n-undesyl group, isoundecyl group, sec-undecyl group, tert-undecyl group, neoundecyl group, n-dodecyl group. , Isododecyl group, sec-dodecyl group, tert-dodecyl group, neododecyl group, n-tridecyl group, isotridecyl group, sec-tridecyl group, tert-tridecyl group, neotridecyl group, n-tetradecyl group, isotetradecyl group, sec- Tetradecyl group, tert-tetradecyl group, neotetradecyl group, n-pentadecyl group, isopentadecyl group, sec-pentadecyl group, tert-pentadecyl group, neopentadecyl group, n-hexadecyl group, isohexadecyl group, sec- Hexadecyl group, tert-hexadecyl group, neohexadecyl group, n-heptadecyl group, isoheptadecyl group, sec-heptadecyl group, tert-heptadecyl group, neoheptadecyl group, n-octadecyl group, isooctadecyl group, sec-octadecyl group, tert- Octadecyl group, neo-octadecyl group, n-nonadesyl group, isononadecyl group, sec-nonadesyl group, tert-nonadesyl group, neononadesyl group, n-icosyl group, isoicosyl group, sec-icosyl group, tert-icosyl group, neoicocil group, n -Henicosyl group, isohenicosyl group, sec-henicosyl group, tert-henicosyl group, neohenicosyl group, n-docosyl group, isodocosyl group, sec-docosyl group, tert-docosyl group, neodocosyl group, n-tricosyl group, isotricosyl group, sec − Tricosyl group, tert-tricosyl group, neotricosyl group, n-tetracosyl group, isotetracosyl group, sec-tetracosyl group, tert-tetracosyl group, neotetracosyl group, n-pentacosyl group, isopentacosyl group, sec-pentacosyl group, tert-pentacosyl group, neopentacosyl group, n-hexacosyl group, isohexacosyl group, sec-hexacosyl group, tert-hexacosyl group, neohexacosyl group, n-heptacosyl group, isoheptacosyl group, sec-heptacosyl group, tert-heptacosyl group, neoheptacosyl group, n-octacosyl group, isooctacosyl group, sec-octacosyl group, tert-octacosyl group, neo-octakosyl group, n-nonacosyl group, isononacosyl group, sec-nonacosyl group, tert-nonacosyl group, neononacosyl group, n-triacontyl group, isotoriacontyl group, sec-triacontyl group, tert-Triacontyl group, neotriacontyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, cycloundesyl group, cyclododecyl group, cyclotridecyl Examples thereof include a group, a cyclotetradecyl group, a cyclopentadecyl group, a cyclohexadecyl group, a cycloheptadecyl group, a cyclooctadecyl group, a cyclononadecil group, a cycloicosyl group and the like.
Examples of the aryl group include a phenyl group which may be substituted with a hydrocarbon group, for example, a phenyl group, a nonylphenyl group, a cresyl group, a 2,4-di-t-butylphenyl group, a tolyl group, a xsilyl group, and the like. Ethylphenyl group and the like can be mentioned.

Examples of the substituent of the alkyl group include an alkoxy group, an aryl group, and a methacryloyl group.

Examples of the alkoxy group as a substituent of the alkyl group include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, an s-butoxy group, a t-butoxy group and an n-. Pentyroxy group, 1-methyl-n-butoxy group, 2-methyl-n-butoxy group, 3-methyl-n-butoxy group, 1,1-dimethyl-n-propoxy group, 1,2-dimethyl-n-propoxy Group, 2,2-dimethyl-n-propoxy group, 1-ethyl-n-propoxy group, n-hexyloxy group, 1-methyl-n-pentyroxy group, 2-methyl-n-pentyroxy group, 3-methyl-n -Pentyroxy group, 4-methyl-n-pentyroxy group, 1,1-dimethyl-n-butoxy group, 1,2-dimethyl-n-butoxy group, 1,3-dimethyl-n-butoxy group, 2,2- Dimethyl-n-butoxy group, 2,3-dimethyl-n-butoxy group, 3,3-dimethyl-n-butoxy group, 1-ethyl-n-butoxy group, 2-ethyl-n-butoxy group, 1,1 , 2-trimethyl-n-propoxy group, 1,2,2-trimethyl-n-propoxy group, 1-ethyl-1-methyl-n-propoxy group, 1-ethyl-2-methyl-n-propoxy group, etc. Can be mentioned.

Examples of the aryl group as a substituent of the alkyl group include a phenyl group, and examples of the alkyl group substituted with the aryl group include a benzyl group, a methylbenzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group and a phenylpentyl group. Phenylhexyl group, phenylheptyl group, phenyloctyl group, phenylnonyl group, phenyldecyl group, diphenylmethyl group, triphenylmethyl group, naphthylmethyl group, diphenylethyl group, phenylmethylethyl group, phenyltrimethyl group, phenylmethylpropyl group , Phenyldimethyl group, phenyldimethylethyl group (all including all substituted isomers and branched isomers) and the like.

Examples of the alkyl group substituted with the methacryloyl group include a methacryloylmethyl group, a methacryloylethyl group, a methacryloylbutyl group, a methacryloylpropyl group and the like.

Examples of the carbonyl compound include a ketone represented by RC (= O) -R'and an aldehyde represented by R-CHO. The carboxylic acid is represented by R-COOH, and the ester is represented by R-COO-R'. Here, R and R'are alkyl or aryl groups, which may have substituents. R and R'may be the same or different. Examples of the alkyl group and aryl group of R and R'include those exemplified as the alkyl group and aryl group of the above-mentioned amine compound, and the same applies to the substituent which the alkyl group may have.

In the IR spectrum, ^{examples of the compound having a peak in the wavelength region of 1800 to 1650 cm -1} include carbonyl compounds, carboxylic acids and esters, and examples of the carbonyl compound, carboxylic acids and esters thereof are 1350 to 150 cm ^-1 . Examples of those having a peak in the wavelength region include those similar to those described above.
Specific examples of amine compounds, carbonyl compounds, carboxylic acids, and esters include the following.

Amine compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, butylamine, dibutylamine, tributylamine, pentylamine, dipentylamine, tripentylamine, methylpentylamine, hexylamine, dihexylamine, trihexyamine, 2 -Ethylhexylamine, heptylamine, diheptylamine, triheptylamine, octylamine, dioctylamine, trioctylamine, nonylamine, dinonylamine, trinonylamine, decylamine, didecylamine, tridecylamine, neodecylamine, undecylamine, diun Decylamine, Triundecylamine, Dodecylamine, Didodecylamine, Tridodecylamine, Tridecylamine, Ditridecylamine, Tritridecyl group, Tetradecylamine, Ditetradecylamine, Tritetradecylamine, Pentadecylamine, Di Pentadecylamine, tripentadecylamine, hexadecylamine, dihexadecylamine, trihexadecylamine, heptadecylamine, diheptadecylamine, triheptadecylamine, octadecylamine, dioctadecylamine, trioctadecilamine, nonadecilamine, Dinonadesylamine, Trinonadesylamine, Icosylamine, Diicosylamine, Triicosylamine, Henicosylamine, Dihenicosylamine, Trihenicosylamine, Docosylamine, Didocosylamine, Tridocosylamine, Tricosylamine, Ditricosylamine , Tritricosylamine, Tetracosylamine, Ditetracosylamine, Tritetracosylamine, Pentacosylamine, Dipentacosylamine, Tripentacosylamine, Hexacosylamine, Dihexacosylamine, Trihexacosylamine, Heptacosylamine , Diheptacosylamine, Triheptacosylamine Octacosylamine, Dioctacosylamine, Trioctacosylamine, Nonacosylamine, Dinonacosylamine, Trinonacosylamine, Triacontylamine, Ditriacontylamine, Tritriacontylamine, Ethylenediamine, Triethanolamine, N, N-diisopyrethylamine, tetramethylethylenediamine, hexamethylenediamine, spermidin, spermin, amantazine, aniline, phenethylamine, toluidine , Pyrrolidine, piperidine, imidazole, pyridine, 4-dimethylaminopyridine and the like.

Carbonyl compounds include acetone, methyl ethyl ketone, diethyl ketone, 2,4-hexadione, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, acetophenone, benzophenone, formaldehyde, acetaldehyde, propionaldehyde, butanal, hexanal, heptanal. , Octanal, nonanal, decanal, formic acid, vinyl aldehyde, benzaldehyde, cinnam aldehyde, peryl aldehyde, vanillin, glyoxal and the like.

Carous acids include formic acid, acetic acid, propionic acid, butyric acid, caproic acid, valeric acid, caproic acid, enanthic acid, capric acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid. , Oleic acid, linoleic acid, linolenic acid, arachidonic acid, eikosapentaenoic acid, docosahexaenoic acid, sorbic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, oxalic acid, malonic acid , Succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, pyruvate, oxaloacetate and the like.

Esters include methyl formate, ethyl formate, methyl acetate, ethyl acetate, octyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, pentyl acetate, isopentyl acetate, methyl caproate, ethyl caproate, valeric acid. Methyl, ethyl valerate, isopentyl valerate, pentyl valerate, methyl caproate, ethyl caproate, methyl enanthate, ethyl enanthate, methyl caprylate, ethyl caprylate, methyl pelargonate, ethyl pelargonate, methyl caprice , Ethyl caprate, methyl laurate, ethyl laurate, methyl myristate, ethyl myristate, methyl palmitate, ethyl palmitate, methyl margarate, ethyl margarate, methyl stearate, ethyl stearate, methyl oleate, olein Ethyl acid, methyl linoleate, ethyl linoleate, methyl linolenate, ethyl linolenate, methyl arachidate, ethyl arachidate, methyl eicosapentaene, ethyl eikosapentanate, methyl docosahexaene, ethyl docosahexaene, methyl salicylate, etc. Can be mentioned.

Further, as the metal contained in the silanol condensation catalyst in the present invention, a metal other than tin is preferable from the viewpoint of environmental load, and zinc, aluminum, zirconium, bismuth, calcium, magnesium, titanium and the like are particularly preferable and thermally stable. Zinc is preferable from the viewpoint of excellent balance between properties, stability in water, and exchange rate with water.

These metals as silanol condensation catalysts may be used alone or in combination of two or more.

The content of the silanol condensation catalyst in the silanol condensation catalyst-containing composition of the present invention is a content capable of exhibiting a function as a silanol condensation catalyst under the conditions of use described later, and is 0.001 to 15 with respect to 100 parts by mass of polyethylene. It is a mass part. The content of the silanol condensation catalyst is preferably 0.01 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of polyethylene. It is preferably 8 parts by mass or less. If the content of the silanol condensation catalyst in the silanol condensation catalyst-containing composition is too small, the cross-linking reaction does not proceed sufficiently, and if it is too large, the appearance of the obtained molded product tends to be deteriorated.

[Silane-modified polyethylene]
A silane crosslinked polyethylene can be obtained by blending a silane-modified polyethylene with the silanol condensation catalyst-containing composition of the present invention and allowing the crosslinking reaction to proceed as described later.

The silane-modified polyethylene that can be used in the present invention is not particularly limited as long as it is obtained by reacting polyethylene with an unsaturated silane compound. As the polyethylene that can be used here, any of the polyethylenes listed as the polyethylene used in the present invention can be used. The unsaturated silane compound that can be used for the silane-modified polyethylene is not particularly limited, but a compound represented by the following formula (1) is preferable.
R ¹ Si (R ² ) ₃ (1)

In the above formula (1), R ¹ is an ethylenically unsaturated hydrocarbon group, R ² is a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms independently of each other, and R ² At least one of them is an alkoxy group having 1 to 10 carbon atoms.

In the formula (1), R ¹ is preferably an ethylenically unsaturated hydrocarbon group having 2 to 10 carbon atoms, and more preferably an ethylenically unsaturated hydrocarbon group having 2 to 6 carbon atoms. Specific examples thereof include alkenyl groups such as vinyl group, propenyl group, butenyl group and cyclohexenyl group.

In the formula (1), R ² is preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and more preferably a hydrocarbon group having 1 to 4 carbon atoms or 1 to 4 carbon atoms. It is an alkoxy group of. Further, ^{at least one of R 2} is preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms.

Hydrocarbon group having 1 to 10 carbon atoms R ² is an alkyl group, an aliphatic group, alicyclic group, may be any aromatic group, it is desirable that the alkyl group. The alkoxy group having 1 to 10 carbon atoms of R ² may be linear, branched or cyclic, but is preferably linear or branched. When R ² is a hydrocarbon group, specifically, an alkyl group represented by a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an n-butyl group, an i-butyl group, a cyclohexyl group, or a phenyl group. Examples thereof include an aryl group typified by a group. When R ² is an alkoxy group, specific examples thereof include a methoxy group, an ethoxy group, an isopropoxy group and a β-methoxyethoxy group.

If the unsaturated silane compound is represented by the formula (1), at least one of the three R ² is an alkoxy group, preferably two R ² is an alkoxy group, all of R ² It is more preferably an alkoxy group.

As the unsaturated silane compound, vinyltrialkoxysilane typified by vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, etc. is desirable among those represented by the formula (1). This is because the vinyl group enables modification to polyethylene, and the alkoxy group promotes the cross-linking reaction described later. That is, the alkoxy group introduced by graft-modifying the modified polyethylene with an unsaturated silane compound reacts with water in the presence of a silanol condensation catalyst to hydrolyze to generate a silanol group, and the silanol groups are dehydrated and condensed. As a result, the modified polyethylenes are bonded to each other and a cross-linking reaction occurs.

As these unsaturated silane compounds, one type may be used alone, or two or more types may be used in combination.

The silane-modified polyethylene used in the present invention preferably has an unsaturated silane compound modification amount (the amount of the unsaturated silane compound introduced into the silane-modified polyethylene by graft modification) of 0.1 to 5% by mass. It is preferable that the amount of modification is at least the above lower limit value from the viewpoint of heat resistance. Further, it is preferable that the modification amount is not more than the above upper limit value from the viewpoint of moldability. From the viewpoint of making these better, the modification amount of the unsaturated silane compound is more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, while more preferably 5. It is 0.0% by mass or less, more preferably 3.0% by mass or less.

The amount of modification of the unsaturated silane compound is the mass ratio of the unsaturated silane compound introduced by graft modification to ethylene before modification, and can be confirmed by the gel fraction. The gel fraction is the mass ratio of the insoluble part after extraction of the xylene boiling point. After the sample is dry-blended with a silanol condensation catalyst, it is injected or extruded under the conditions for molding a normal polyolefin resin, and crosslinked with warm water at 80 ° C. for 24 hours. , The sample can be confirmed by soxley extraction with xylene and measuring the mass after drying xylene.

The silane-modified polyethylene may be graft-modified by using a compound other than the unsaturated silane compound in combination as long as the effects of the present invention are not impaired. Specific examples of the compounds other than the unsaturated silane compound include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, etacrilic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid and isocrotonic acid. Examples thereof include acids and their acid anhydrides.

The silane-modified polyethylene can be produced by graft-modifying the above unsaturated silane compound on polyethylene. The method of graft denaturation is not particularly limited and can be carried out according to a known method. For example, solution denaturation, melt denaturation, solid phase denaturation by irradiation with electron beam or ionizing radiation, denaturation in a supercritical fluid, etc. are preferable. Used for. Among these, melt modification having excellent equipment and cost competitiveness is preferable, and melt kneading modification using an extruder having excellent continuous productivity is more preferable. Examples of the apparatus used for melt-kneading modification include a single-screw screw extruder, a twin-screw screw extruder, a Banbury mixer, a roll mixer, and the like. Among these, a single-screw screw extruder and a twin-screw screw extruder having excellent continuous productivity are preferable.

Generally, the graft modification of an unsaturated silane compound to polyethylene is carried out by a graft reaction in which a carbon-hydrogen bond of polyethylene is cleaved to generate a carbon radical, and an unsaturated functional group is added to the carbon radical. As the source of carbon radicals, in addition to the above-mentioned electron beam and ionizing radiation, a method of raising the temperature or a radical generator such as an organic or inorganic peroxide can be used. It is preferable to use an organic peroxide from the viewpoint of cost and operability.

The radical generator used in producing the silane-modified polyethylene is not limited, and for example, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxy ester, and organic peroxide contained in the ketone peroxide group, and Examples include azo compounds.

Specifically, for example, the hydroperoxide group includes cumene hydroperoxide, tert-butyl hydroperoxide and the like, and the dialkyl peroxide group includes dicumyl peroxide, di-tert-butyl peroxide, 2, 5-Dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexin-3, etc. are included, and the diacyl peroxide group includes lauryl. Includes peroxide, benzoyl peroxide and the like. The peroxyester group includes tert-peroxyacetate, tert-butylperoxybenzoate, tert-butylperoxyisopropylcarbonate and the like, and the ketone peroxide group includes cyclohexanone peroxide and the like. Examples of the azo compound include azobisisobutyronitrile and methylazoisobutyrate.

One type of these radical generators may be used alone, or two or more types may be used in combination.

A commonly used operation for melt extrusion modification is to mix polyethylene, an unsaturated silane compound, and an organic peroxide, blend them, put them into a kneader or extruder, and extrude while heating, melt, and knead the tip. The molten resin coming out of the die is cooled in a water tank or the like to obtain silane-modified polyethylene.

The blending ratio of polyethylene and the unsaturated silane compound is not particularly limited, but the preferable blending range is 0.5 to 10 parts by mass of the unsaturated silane compound with respect to 100 parts by mass of polyethylene. If the amount of unsaturated silane compound is too small with respect to polyethylene, the predetermined amount of modification required to achieve the desired effect may not be obtained, and if it is too large, a large amount of unreacted unsaturated silane compound remains. However, it may adversely affect the performance.

The blending ratio of the unsaturated silane compound and the organic peroxide is not particularly limited, but the preferable blending range is 0.01 to 5 mass by mass of the organic peroxide with respect to 100 parts by mass of the unsaturated silane compound. It is a department. When the amount of the organic peroxide with respect to the unsaturated silane compound is not less than the above lower limit value, a sufficient amount of radicals are easily generated to obtain the required predetermined amount of modification, and the amount is not more than the above upper limit value. It tends to be easier to suppress the deterioration of polyethylene.

Further, as the melt extrusion modification conditions, for example, in a single-screw screw extruder and a twin-screw screw extruder, extrusion is preferably performed at a temperature of about 150 to 300 ° C.

When the silanol condensation catalyst-containing composition of the present invention contains silane-modified polyethylene, the polyethylene and the silanol condensation catalyst may be contained in a total of 0.01 to 30 parts by mass with respect to 100 parts by mass of the silane-modified polyethylene. It is preferably contained in an amount of 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass. If the total content of the polyethylene and silanol condensation catalyst with respect to the silane-modified polyethylene is too small, the cross-linking reaction does not proceed sufficiently, and if it is too large, the appearance of the obtained molded product tends to deteriorate.

[Other ingredients]
The silanol condensation catalyst-containing composition of the present invention includes the following additives and resins other than polyethylene (hereinafter, “others”, depending on various purposes, as long as the effects of the present invention are not significantly impaired in addition to the components listed above. Any component such as "resin") can be blended.

Additives include antioxidants, lubricants, colorants, heat stabilizers, light stabilizers, UV absorbers, neutralizers, cloud proofing agents, anti-blocking agents, slip agents, flame retardants, dispersants, antistatic agents. , Conductivity-imparting agent, metal inactivating agent, molecular weight adjusting agent, antibacterial agent, fluorescent whitening agent and the like. Depending on the purpose, these components may be used alone or in combination of two or more.

Examples of the antioxidant include a phenol-based antioxidant, a sulfide-based antioxidant, a thioether-based antioxidant, and the like. When an antioxidant is used, it is usually used in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass in total of polyethylene and silane-modified polyethylene.

Examples of the lubricant include oleic acid amide, erucic acid amide, silicone oil and the like. When a lubricant is used, it is usually used in the range of 0.01 to 3 parts by mass with respect to a total of 100 parts by mass of polyethylene and silane-modified polyethylene.

Other resins that can be contained in the silanol condensation catalyst-containing composition of the present invention include styrene-based thermoplastic elastomers, polyester resins, polyamide resins, styrene resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, and polyolefin resins (however, Examples thereof include those corresponding to polyethylene or silane-modified polyethylene (excluding those corresponding to polyethylene or silane-modified polyethylene), various elastomers (excluding those corresponding to polyethylene or silane-modified polyethylene), and the like. The other resins listed above may contain only one type or two or more types. Other resins are usually used in an amount of 50 parts by mass or less with respect to 100 parts by mass of polyethylene or silane-modified polyethylene.

[Preparation of composition containing silanol condensation catalyst]
The silanol condensation catalyst-containing composition of the present invention containing polyethylene as a master batch of silanol condensation catalyst and silanol condensation catalyst contains a silanol condensation catalyst, polyethylene, and other components used as necessary, biaxially at 120 to 230 ° C. It can be prepared by kneading with a kneader or the like and pelletizing if necessary.

[Silane cross-linked polyethylene]
In the silanol condensation catalyst-containing composition of the present invention, silane crosslinked polyethylene can be obtained by blending the above-mentioned silane-modified polyethylene and subjecting it to a crosslink reaction. In this cross-linking reaction, a silanol condensation catalyst-containing composition containing silane-modified polyethylene is usually molded by various molding methods such as extrusion molding, injection molding, and press molding, and then exposed to an aqueous atmosphere to carry out a cross-linking reaction between silanol groups. It can be carried out by advancing. Various conditions can be adopted as the method of exposing to the water atmosphere, the method of leaving in the air containing moisture, the method of blowing air containing water vapor, the method of immersing in a water bath, and the method of sprinkling hot water in a mist form. There is a method of making it.

In this cross-linking reaction, a silanol group is generated by reacting and hydrolyzing a hydrolyzable alkoxy group in a silane-modified polyethylene with water in the presence of the silanol condensation catalyst in the silanol condensation catalyst-containing composition of the present invention. Then, the silanol groups are dehydrated and condensed to proceed with the cross-linking reaction, and the silane-modified polyethylenes are bonded to each other to form a silane-crosslinked polyethylene.

The rate of progress of the crosslinking reaction depends on the conditions of exposure to the water atmosphere, but it is usually sufficient to expose in a temperature range of 20 to 130 ° C. and a range of 10 minutes to 2 weeks. Particularly preferable conditions are a temperature range of 60 to 110 ° C. and a range of 1 hour to 160 hours, but according to the present invention, the crosslinking reaction can sufficiently proceed even under temperature conditions of less than 60 ° C. When using moist air, the relative humidity is selected from the range of 1-100%.

In order for the silane cross-linked polyethylene to exhibit excellent properties over a long period of time, the gel fraction (crosslinking degree) of the silane cross-linked polyethylene is preferably 30% or more, more preferably 40% or more. It is more preferably 50% or more, and particularly preferably 60% or more. The gel fraction can be determined by changing the graft ratio (modification amount) of the unsaturated silane compound of silane-modified polyethylene, the type and blending amount of the metal compound as a silanol condensation catalyst, and the conditions (temperature, time) for cross-linking. Can be adjusted. The upper limit of the gel fraction is not particularly limited, but is usually 100% (completely crosslinked) or less, preferably 90% or less. Here, the gel fraction represents the mass of the insoluble matter when extracted with boiling xylene for 10 hours using a Soxhlet extractor as a percentage of the mass before extraction. Measured by the method described in the Examples section below.

[Molded product]
As described above, the silanol condensation catalyst-containing composition of the present invention and the silane cross-linked polyethylene obtained by using the composition can be formed into a molded product by various molding methods such as extrusion molding, injection molding and press molding. This molded body can be suitably used in various shapes and modes such as electric wire / cable covering materials, pipes, hoses, tubes, various containers, sealing materials, films and sheets.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable ranges are the above-mentioned upper limit or lower limit values and the following. It may be in the range specified by the value of Examples or the combination of the values of Examples.

[Example 1-1 and Comparative Example 1-1]
<Raw materials>
The following raw materials were used.
(Silanol condensation catalyst)
-Silanol condensation catalyst-1 (K-KAT670 manufactured by King Industries, Inc. (registered trademark, containing less than 10 to 20% of alkylamine, less than 1 to 3% of zinc compound, less than 80 to 90% of other components)
-Silanol condensation catalyst-2 (for comparative example) (manufactured by Wako Pure Chemical Industries, Ltd., zinc octylate)
The IR spectrum chart of the silanol condensation catalyst-1 is shown in FIG. 1, and the IR spectrum chart of the silanol condensation catalyst-2 is shown in FIG. 2, respectively.

(polyethylene)
-Polyethylene-1: "Novatec (registered trademark) LD400" manufactured by Japan Polyethylene Corporation (MFR (190 ° C., 21.2N): 2 g / 10 minutes, density: 0.92 g / cm ³ )
-Polyethylene-2: "Novatec (registered trademark) LD400P" manufactured by Japan Polyethylene Corporation (MFR (190 ° C, 21.2N): 2 g / 10 minutes, density: 0.92 g / cm ³ )

(Other ingredients)
-Antioxidant-1: BASF's Irganox 1010
-Antioxidant-2: BASF's Irganox MD1024
-Antioxidant-3: Sumitomo Chemical's Sumilyzer (registered trademark) WXRC
-Glidant-1: DuPont Viton (registered trademark) Free Flow SCPL100

<Manufacturing of silanol condensation catalyst masterbatch>
Each of the above raw materials was kneaded at a blending ratio shown in Table 1 at a set temperature of a twin-screw kneader at 180 ° C., and the obtained mixture was pelletized with a pelletizer to produce a silanol condensation catalyst masterbatch.

[Example 2-1 and Comparative Example 2-1]
<Raw materials>
The following raw materials were used.
-Silane-modified polyethylene (manufactured by Mitsubishi Chemical Corporation, Linkron (registered trademark) XCF800N)
-Silanol condensation catalyst masterbatch (manufactured in each of Example 1-1 and Comparative Example 1-2)

<Manufacture and evaluation of silanol condensation catalyst-containing composition and silane cross-linked polyethylene>
A mixture of 5 parts by mass of silanol condensation catalyst masterbatch with 100 parts by mass of silane-modified polyethylene (Linkron XCF800N, manufactured by Mitsubishi Chemical Corporation) is extruded with a 20 mmφ extruder at a temperature of 210 ° C. to prepare an extruded sheet with a thickness of 1 mm. bottom. Using the obtained extruded sheet, cross-linking treatment was carried out under the following cross-linking treatment conditions I to III to obtain silane cross-linked polyethylene.
The gel fraction of the obtained extruded sheet of silane cross-linked polyethylene was measured by the following method.
The results are shown in Table 2.

Crosslinking condition I: Immerse in steam at 95 ° C. for 7 hours.
Crosslinking condition II: Immerse in warm water at 80 ° C. for 7 hours.
Crosslinking Condition III: Exposure at 23 ° C. and 50% RH for 336 hours.

(Measurement of gel fraction)
A sheet of silane cross-linked polyethylene (thickness 1 mm) was extracted with Soxhlet in boiling xylene at 144 ° C. for 10 hours, and the undissolved resin was weighed after drying and calculated as a ratio (%) to the sample mass before Soxhlet extraction. bottom.

<Evaluation result>
As is clear from the gel fraction values shown in Table 2, Example 2-1 shows a better gel fraction than Comparative Example 2-1 under any of the cross-linking treatment conditions, and in the IR spectrum, it shows a better gel fraction. It is recognized that the silanol condensation catalyst-1 containing a compound and a metal having a peak in the wavelength region of 1350 to 150 cm ^-1 and 1800 to 1650 cm ^{-1 has high catalytic activity.} On the other hand, the silanol condensation catalyst-2 has a lower gel fraction than the case where the silanol condensation catalyst-1 is used under any of the cross-linking treatment conditions, and particularly under the low temperature condition of the cross-linking treatment condition III, silane cross-linking is performed. The gel fraction required for polyethylene cannot be met.
Silanol condensation catalyst-1 is an environmentally low-load silanol condensation catalyst that can replace known zinc compound catalysts and organotin compounds, and its usefulness is great.

Claims (5)

In IR spectrum, an amine compound having a peak in a wavelength region of 1350～1050Cm ^-1, carbonyl compounds having a peak in a wavelength region of 1350～1050Cm ^-1 and 1800～1650Cm ^-1 in the IR spectrum, carboxylic acids, from esters A silanol condensation catalyst containing a selected compound, a silanol condensation catalyst containing zinc, and polyethylene, and the content of the silanol condensation catalyst is 5 to 15 parts by mass with respect to 100 parts by mass of polyethylene. Containing composition. The silanol condensation catalyst-containing composition according to claim 1, further comprising silane-modified polyethylene, and containing 0.01 to 30 parts by mass of the polyethylene and the silanol condensation catalyst in total with respect to 100 parts by mass of the silane-modified polyethylene. A silane cross-linked polyethylene which is a cross-linking reaction product of the silanol condensation catalyst-containing composition according to claim 2. The molded product of silane cross-linked polyethylene according to claim 3. The molded product according to claim 4, wherein the molded product is an electric wire coating material, a pipe, a hose, a film, or a sheet.

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