JP2020152834A - TUBULAR BODY, PIPE, HOSE, AND MODIFIED ETHYLENE-α-OLEFIN COPOLYMER - Google Patents

Abstract

To provide: a tubular body, pipe, and hose which can decrease difficulty in bending as a cross-linked pipe product, is easy to correct curl persistence by bending and stretching, and has a high gel fraction; and a modified ethylene-α-olefin copolymer suitable for producing these.SOLUTION: The tubular body is formed of a silane-crosslinked ethylene-α-olefin copolymer obtained by subjecting a modified ethylene-α-olefin copolymer, which is an ethylene-α-olefin copolymer graft-modified with an unsaturated silane compound, to a crosslinking reaction in the presence of a crosslinking catalyst. The modified ethylene-α-olefin copolymer satisfies the following (1) to (3): (1) the α-olefin, which is a constituent unit, includes propylene; (2) a gel fraction is 65% by mass or more; and (3) a melt flow rate (MFR) at 190°C and 2.16 kg is 0.05 to 2 g/10 minutes.SELECTED DRAWING: None

Description

The present invention relates to tubulars, pipes and hoses and modified ethylene / α-olefin copolymers.

Plastic, which is superior in corrosion resistance and workability compared to metal materials, is used as a material for tubular bodies, especially pipes and hoses for water and hot water supply. Among these, the mainstream is to use a so-called silane-modified polyethylene cross-linked pipe (hereinafter referred to as a cross-linked pipe), which is obtained by cross-linking unsaturated silane-modified polyethylene, which is particularly excellent in pressure resistance and creep resistance in a high temperature region. ..

Cross-linked pipes are generally produced by a method of cross-linking a pipe obtained by mixing and molding polyethylene, an organic unsaturated silane compound, an organic peroxide and a silanol condensation catalyst in the presence of water. The manufacturing method includes a monosyl method in which the above materials are mixed at once to form a pipe, and a silane-modified polyethylene is once prepared using polyethylene, an organic unsaturated silane compound, and an organic peroxide, and the pipe is formed. Occasionally, there is a two-step method in which a silanol condensation catalyst is added for molding.

In all of these methods, it is the mainstream to produce a crosslinked pipe using high-density polyethylene having a high melting point as a raw material in order to exhibit heat resistance in the boiling point region of water.
Patent Document 1 describes a crosslinked polyolefin pipe containing silicone oil as a crosslinked polyolefin pipe having an extended durable life (particularly, a durable life when the pipe is bent and piped) while suppressing changes in pipe physical properties such as elongation at break. It is disclosed.

Japanese Unexamined Patent Publication No. 2017-40299

As described above, the crosslinked pipe is manufactured by a method of cross-linking the molded pipe in the presence of moisture. In this case, the pipe is usually wound into a roll after molding, and is subjected to high temperature and high humidity. Alternatively, hot water is passed through the inside of the pipe for cross-linking treatment. The cross-linking treatment time is usually 16 to 24 hours, and the pipe is shrunk in a roll state by the molding and cross-linking treatment. Therefore, when the pipe is pulled out from the roll-shaped raw fabric during construction, the pipe is pulled out in a wavy state with a curl (bending habit). Therefore, at the time of construction, it is necessary to bend back this curl, and at this time, an unreasonable force is applied to deteriorate the mechanical characteristics such as creep performance, which causes a problem such as water leakage. In addition, if the crosslinked pipe is excessively bent and stretched according to the shape of the construction site, there is a problem that initial mechanical properties and long-term creep defects occur.

As a countermeasure, there is a method of performing the cross-linking process with the pipe stretched in a straight line, but in this case, the cross-linking equipment becomes large and it has a great influence on the cost, so it can be said that it is an industrially advantageous method. Absent.

The crosslinked polyolefin pipe described in Patent Document 1 uses a special silicone oil, and since the amount of the silicone oil added is small, the gel fraction is low, the crosslinking is not sufficient, and the creep resistance is sufficient. I am not satisfied with it.

The present invention has been made in view of the above problems, and is capable of reducing the difficulty of bending as a crosslinked pipe product, easily correcting curl by bending and stretching, and a tubular body, a pipe and a pipe having a high gel content. It is an object of the present invention to provide hoses and modified ethylene / α-olefin copolymers suitable for producing them.

As a result of diligent research to solve the above problems, the present inventor has conducted intensive studies to solve the above-mentioned problems. Among the ethylene / α-olefin copolymers, those containing propylene as a constituent unit, particularly ethylene / α-containing a propylene / ethylene copolymer. A tubular body obtained by cross-linking a modified ethylene / α-olefin copolymer graft-modified with an unsaturated silane compound using an olefin copolymer having a specific melt flow rate and gel fraction. , The present invention has been found by finding that the above-mentioned problems can be solved.
That is, the present invention is as follows.

[1] Silane-crosslinked ethylene / α-olefin copolymer obtained by cross-linking a modified ethylene / α-olefin copolymer obtained by graft-modifying an ethylene / α-olefin copolymer with an unsaturated silane compound in the presence of a crosslinking catalyst. A tubular body made of a coalescence, wherein the modified ethylene / α-olefin copolymer satisfies the following (1) to (3).
(1) Α-olefin as a constituent unit contains propylene (2) Gel fraction is 65% by mass or more (3) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min to 2 g. / 10 minutes

[2] The description in [1], wherein the ethylene / α-olefin copolymer is a mixture containing an ethylene / propylene copolymer and an ethylene / α-olefin copolymer other than the ethylene / propylene copolymer. Tubular body.

[3] The tubular body according to [2], wherein the ethylene content index measured and calculated by the following method for the ethylene / α-olefin copolymer mixture is 0.10 to 0.95.
<Measurement / calculation method of ethylene content index of ethylene / α-olefin copolymer mixture>
A sheet of an ethylene / α-olefin copolymer mixture having a film thickness of 100 μm was subjected to FT-IR measurement in a transmission mode under the following measurement conditions, and calculated by the following calculation method.
<Measurement conditions>
Number of integrations: 32
Disassembly: 4 cm ^-1
Scan speed: 2 mm / sec
<Calculation method>
Ethylene content index = (peak height derived from ethylene group of ethylene / α-olefin copolymer mixture)
/ (For the propylene group of the ethylene / α-olefin copolymer mixture
Sum of peak height derived from and peak height derived from methylene group)

[4] The tubular according to any one of [1] to [3], wherein the end peak temperature of melting measured by a differential scanning calorimeter (DSC) of the ethylene / α-olefin copolymer is 160 ° C. or higher. body.

[5] The tubular body according to any one of [1] to [4], wherein the cross-linking catalyst is a silanol condensation catalyst.

[6] The pipe made of a tubular body according to any one of [1] to [5].

[7] The hose made of the tubular body according to any one of [1] to [5].

[8] A modified ethylene / α-olefin copolymer obtained by graft-modifying an ethylene / α-olefin copolymer containing an ethylene / propylene copolymer with an unsaturated silane compound, wherein the modified ethylene / α-olefin copolymer weight is used. A modified ethylene / α-olefin copolymer in which the coalescence satisfies the following (1) to (3).
(1) Α-olefin as a constituent unit contains propylene (2) Gel fraction is 65% by mass or more (3) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min to 2 g. / 10 minutes

Since the tubular body of the present invention has a low shrinkage rate, less shrinkage stress is generated during cross-linking, so that it is easy to correct the curl and bend it. Therefore, the tubular body of the present invention is easy to construct when used as a pipe or hose for water supply / hot water supply. In addition, it is expected that the durable life will be improved when the work is bent.

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 specification, 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.

[Modified ethylene / α-olefin copolymer]
The modified ethylene / α-olefin copolymer of the present invention used as a raw material for the tubular body of the present invention satisfies the following conditions (1) to (3).
(1) Α-olefin as a constituent unit contains propylene (2) Gel fraction is 65% by mass or more (3) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min to 2 g / 10 minutes The modified ethylene / α-olefin copolymer of the present invention is an ethylene / α-olefin copolymer graft-modified with an unsaturated silane compound. Further, the fact that the modified ethylene / α-olefin copolymer contains propylene as a constituent unit of α-olefin is equivalent to the fact that the ethylene / α-olefin copolymer before silane modification contains propylene as a constituent unit.

<Ethylene / α-olefin copolymer>
Examples of the ethylene / α-olefin copolymer used in the present invention include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and the ethylene / α-olefin copolymer is a constituent unit. It is characterized by containing propylene as an α-olefin, that is, containing an ethylene / propylene copolymer. Preferably, the ethylene / α-olefin copolymer used in the present invention is a mixture containing an ethylene / propylene copolymer and an ethylene / α-olefin copolymer other than the ethylene / propylene copolymer (hereinafter, “ethylene ・”. It may be referred to as "α-olefin copolymer mixture").

In an ethylene / α-olefin copolymer other than the ethylene / propylene copolymer (hereinafter, may be referred to as “other ethylene / α-olefin copolymer”), the number of carbon atoms to be copolymerized with ethylene is 4 to 20. As α-olefins, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl Examples thereof include -1-butene, 4-methyl-1-pentene and 6-methyl-1-heptene, and the α-olefin copolymerized with ethylene is preferably 1-butene, 1-hexene and 1-octene. ..

The ethylene / α-olefin copolymer contains propylene as the α-olefin which is a constituent unit, that is, if it contains an ethylene / propylene copolymer, the common weight of ethylene and one type of α-olefin. It may be a coalescence, or it may be a copolymer in which ethylene and two or more kinds of α-olefins are combined. Further, a single ethylene / α-olefin copolymer or an ethylene / α-olefin copolymer mixture in which two or more types of ethylene / α-olefin copolymers are mixed may be used, but from the viewpoint of compatibility, two types may be used. It is preferable that the ethylene / α-olefin copolymer mixture is a mixture of the above ethylene / α-olefin copolymer.

In other ethylene / α-olefin copolymers, one or more α-olefins (2 to 45% by mass) and ethylene (55 to 98% by mass) are copolymerized as a constituent unit constituting the copolymer. Is preferable.
Further, as the ethylene / propylene copolymer, it is preferable that the proportion of propylene as a constituent unit constituting the copolymer is 55 to 98% by mass and the proportion of ethylene is 2 to 45% by mass.

When the ethylene / α-olefin copolymer is a mixture of two or more types of ethylene / α-olefin copolymers, the proportion of the ethylene / propylene copolymer in the mixture is 0.20 to 30. The mass% is preferable, more preferably 2 to 25% by mass, and particularly preferably 5 to 22% by mass. When this ratio is 30% by mass or less, the extruded appearance of the tubular body is good, and the gel fraction after the cross-linking treatment tends to be improved. On the other hand, if it is 0.2% by mass or more, it tends to be easily bent as a crosslinked pipe.

When the ethylene / α-olefin copolymer is a mixture of an ethylene / propylene copolymer and another ethylene / α-olefin copolymer, the ethylene / propylene copolymer and the other ethylene / α-olefin copolymer weight. The compatibility with the coalescence can be evaluated as an ethylene content index measured and calculated by the following method for the ethylene / α-olefin copolymer mixture.
<Measurement / calculation method of ethylene content index of ethylene / α-olefin copolymer mixture>
A sheet of an ethylene / α-olefin copolymer mixture having a film thickness of 100 μm was subjected to FT-IR measurement in a transmission mode under the following measurement conditions, and calculated by the following calculation method.
<Measurement conditions>
Number of integrations: 32
Disassembly: 4 cm ^-1
Scan speed: 2 mm / sec
<Calculation method>
Ethylene content index = (peak height derived from ethylene group of ethylene / α-olefin copolymer mixture)
/ (For the propylene group of the ethylene / α-olefin copolymer mixture
Sum of peak height derived from and peak height derived from methylene group)

The details of the method for measuring and calculating the ethylene content index are as described in the section of Examples described later. In the present invention, the ethylene content index of the ethylene / α-olefin copolymer mixture is 0.10 to 0. It is preferably .95, more preferably 0.25 to 0.90, even more preferably 0.50 to 0.85, and particularly preferably 0.55 to 0.80. When the ethylene content index is 0.10 or more, the tubular body after cross-linking as a modified ethylene / α-olefin copolymer is unlikely to become hard, and the gel fraction is also improved, so that sufficient bendability can be obtained. It can be made and tends to have excellent creep performance. On the other hand, when the ethylene content index is 0.95 or less, the shrinkage rate after cross-linking tends to be suppressed, and the tubular body does not have an excessive curl and tends to be easily rewound.
Since the ethylene / propylene copolymer has a high melting point, the shrinkage rate after crosslinking tends to be low. A tubular body such as a pipe is wound into a roll after extrusion molding and is crosslinked as it is, so that it becomes curly due to shrinkage due to molding and crosslinking. Therefore, a molding material having a small shrinkage is a material that can be easily rewound because the curling effect due to cross-linking is reduced.

The ethylene / α-olefin copolymer can be produced by copolymerizing ethylene and α-olefin in the presence of a catalyst according to a conventional method. As the catalyst used at that time, a Ziegler-Natta catalyst, a metallocene catalyst, or the like can be used, but a Ziegler-Natta catalyst is preferable in consideration of availability in the required density range. The ethylene / α-olefin copolymer obtained by using a metallocene catalyst is usually mainly composed of a material having a low density.

The density of the ethylene · alpha-olefin copolymer, 880 kg / ^{m 3} or more, preferably 965 kg / ^{m 3} or less, more preferably 890 kg / ^{m 3} or more and 960 kg / ^{m 3} or less.
The density of the ethylene-propylene copolymer among the ethylene-alpha-olefin copolymer, 860 kg / ^{m 3} or more, preferably 920 kg / ^{m 3} or less, more preferably 880 kg / ^{m 3} or more, 910 kg / ^{m 3} or less Is.

The density of the ethylene / α-olefin copolymer can be adjusted mainly by the amount of other α-olefins copolymerized with ethylene, etc., and is approximately modified ethylene / α- after graft modification with an unsaturated silane compound. Equal to an olefin copolymer.
When the density of the ethylene / α-olefin copolymer is not more than the above upper limit, the rigidity of the crosslinked body obtained by crosslinking and the tubular body such as a pipe does not become too high, and for example, the pipe workability of the pipe is good. Become. When the density of the ethylene / α-olefin copolymer is equal to or higher than the above lower limit, long-term durability, particularly creep resistance and heat resistance tend to be good.
Here, the density of the ethylene / α-olefin copolymer is measured by the method described in JIS K7112 (1999).

The melt flow rate (MFR) of the ethylene / α-olefin copolymer used in the present invention at 190 ° C. and 2.16 kg is preferably 0.5 g / 10 minutes or more and 5 g / 10 minutes or less, more preferably. 1.0 g / 10 minutes or more and 2 g / 10 minutes or less.

If the MFR of the ethylene / α-olefin copolymer at 190 ° C. and 2.16 kg is 0.5 g / 10 minutes or more, the viscosity at the time of modification does not become too high and the extrusion characteristics at the time of modification are also good. At the same time, it is possible to suppress a decrease in MFR of the obtained modified ethylene / α-olefin copolymer, and as a result, an increase in pressure during molding of a tubular body such as a pipe can be suppressed. Therefore, good extrusion moldability can be obtained without problems such as torque abnormality and generation of melt fracture that deteriorates the surface property. On the other hand, if the MFR of the ethylene / α-olefin copolymer is 5 g / 10 minutes or less, the MFR of the obtained modified ethylene / α-olefin copolymer is also low, and drawdown during molding of a tubular body such as a pipe is performed. It is possible to obtain good extrusion moldability by suppressing the occurrence of

The MFR of the ethylene / α-olefin copolymer and the modified ethylene / α-olefin copolymer of the present invention described later is measured at 190 ° C. and a load of 2.16 kg by the method described in JIS K7210.
However, the MFR of the ethylene / propylene copolymer is measured by the method described in JIS K7210 at 230 ° C. and a load of 2.16 kg.

Further, the ethylene / α-olefin copolymer used in the present invention has a melting end peak temperature (hereinafter sometimes referred to as “melting end point”) measured by a differential scanning calorimeter (DSC) of 160 ° C. or higher. Is preferable. When the melting end point of the ethylene / α-olefin copolymer is 160 ° C. or higher, the shape can be maintained by crystals even at a high temperature. From this viewpoint, the melting end point of the ethylene / α-olefin copolymer is preferably 120 ° C. or higher, particularly preferably 135 ° C. or higher. However, if the melting end point of the ethylene / α-olefin copolymer is excessively high, there is a risk that the appearance will be poor due to unmelted lumps when the temperature of the molding is raised and early crystallization (melt fracture) when the molding is cooled. Therefore, the melting end point of the ethylene / α-olefin copolymer is usually preferably 175 ° C. or lower.
The melting end point of the ethylene / α-olefin copolymer is measured by the method described in the section of Examples described later.

In the present invention, as the ethylene / α-olefin copolymer, a commercially available product can be used, and for example, a Novatex series manufactured by JPE, Q300F manufactured by Lyodorlbasell, etc. can be selected and used. Further, as the ethylene / α-olefin copolymer, only one type may be used, or two or more types of comonomer having different types and physical properties of α-olefin may be mixed and used. As described above, preferably, an ethylene / propylene copolymer and another ethylene / α-olefin copolymer are mixed and used.
When two or more kinds of ethylene / α-olefin copolymers are mixed and used, the MFR and density of each ethylene / α-olefin copolymer may be within the above range.

<Modified ethylene / α-olefin copolymer>
The modified ethylene / α-olefin copolymer of the present invention is obtained by graft-modifying the above ethylene / α-olefin copolymer with an unsaturated silane compound and hydrolyzing the above ethylene / α-olefin copolymer. It can be obtained by copolymerizing an olefinically unsaturated silane compound with a possible organic group in the presence of a radical generator. In this reaction, the unsaturated silane compound is grafted onto the ethylene / α-olefin copolymer so as to be a cross-linking point between the base ethylene / α-olefin copolymers.

Here, as the olefinically unsaturated silane compound having a hydrolyzable organic group, a silane compound represented by the following general formula (1) is preferably used.
_{RSiR 'n Y 3-n (} 1)
(In the formula (1), R represents a monovalent olefinically unsaturated hydrocarbon group, Y represents an organic group that can be hydrolyzed, and R'is a monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon. Alternatively, it indicates the same as Y, and n indicates 0, 1 or 2).

In the general formula (1), R is preferably a vinyl group, an allyl group, an isopropenyl group, a butenyl group or the like, R'is preferably a methyl group, an ethyl group, a propyl group, a decyl group, a phenyl group or the like, and Y is a methoxy group. , Ethoxy group, formyloxy group, acetoxy group, propionoxy group, alkyl or arylamino group are preferable.

Further, as a more preferable unsaturated silane compound, for example, a compound represented by the following general formula (2) can be mentioned.
CH ₂ = CHSi (OA) ₃ (2)
(In formula (2), A represents a monovalent hydrocarbon group having 1 to 8 carbon atoms.)
Specific examples of the unsaturated silane compound represented by the general formula (2) include vinyltrimethoxysilane and vinyltriethoxysilane.

As the unsaturated silane compound, a compound represented by the following general formula (3) can also be preferably used.
CH ₂ = C (CH ₃ ) COOC ₃ H ₆ Si (OA) ₃ (3)
(In equation (3), A is synonymous with equation (2).)
Examples of the unsaturated silane compound represented by the general formula (3) include γ-methacryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltriethoxysilane.

Among these, as the unsaturated silane compound, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltriethoxysilane are preferable.

One of these unsaturated silane compounds may be used alone, or two or more thereof may be used in combination in any combination.

The amount of the unsaturated silane compound added for the graft modification is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.% by mass, based on the total mass of the ethylene / α-olefin polymer. It is 7% by mass or more, usually 15% by mass or less, preferably 10% by mass or less, more preferably 7% by mass or less, still more preferably 4% by mass or less. If the amount of the unsaturated silane compound added is too small, sufficient grafting tends to be difficult, and if it is too large, it tends to cause the occurrence of eye shavings and is not economical. Here, the amount of the unsaturated silane compound added has the same meaning as the unit derived from the unsaturated silane compound in the modified ethylene / α-olefin copolymer.

Radical generators used during graft modification include various organic peroxides and peresters having a strong polymerization initiating action, such as dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, and the like. Di-t-butyl peroxide, t-butyl cumyl peroxide, di-benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypivalate, di Examples thereof include -t-butyl peroxide and t-butylperoxy-2-ethylhexanoate. Of these, dicumyl peroxide, benzoyl peroxide, and di-t-butyl peroxide are preferable. These radical generators may be used alone or in any combination of two or more.

The amount of the radical generator added needs to be adjusted so that the MFR of the obtained modified ethylene / α-olefin copolymer is finally within the following MFR range, but the obtained modified ethylene / α-olefin is obtained. Based on the total mass of the copolymer, it is usually 0.01% by mass or more, preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and usually 0.5% by mass or less, preferably 0.5% by mass or less. It is 0.4% by mass or less, more preferably 0.2% by mass or less. If the amount of the radical generator used is too small, the sufficient grafting reaction tends to be difficult, and if it is too large, the MFR of the obtained modified ethylene / α-olefin copolymer is lowered, and the extrusion processability is lowered. As a result, the molded surface tends to deteriorate.

The melt flow rate (MFR) of the modified ethylene / α-olefin copolymer of the present invention at 190 ° C. and 2.16 kg is 0.05 g / 10 minutes or more and 2 g / 10 minutes or less. This MFR is preferably 0.1 g / 10 minutes or more, and preferably 1 g / 10 minutes or less.

If the MFR of the modified ethylene / α-olefin copolymer is lower than 0.05 g / 10 minutes, the pressure during molding of a tubular body such as a pipe will increase significantly, for example, torque abnormality or deterioration of surface properties. Extrusion formability deteriorates due to the generation of melt fractures. On the other hand, if the MFR of the modified ethylene / α-olefin copolymer exceeds 2 g / 10 minutes, the extrusion moldability also deteriorates due to the occurrence of drawdown during molding of a tubular body such as a pipe.

The density of the modified ethylene / α-olefin copolymer of the present invention is preferably 880 kg / m ³ or more and 965 kg / m ³ or less, more preferably 890 kg, as in the case of the ethylene / α-olefin copolymer before modification. / M ³ or more and 960 kg / m ³ or less.
The density of the modified ethylene / α-olefin copolymer is measured according to the JIS K7112 (1999) A method.

Further, the modified ethylene / α-olefin copolymer of the present invention needs to have a gel fraction of 65% by mass or more. This is generally specified by JIS K6769, which is a standard for cross-linked polyethylene pipes, and JXP A401, which is a standard for polyethylene pipes for heating. Here, the gel fraction is an index indicating the degree of cross-linking of the resin, and it can be said that if the gel fraction is large, the cross-linking degree is high, and conversely, if the gel fraction is small, the cross-linking degree is low. If the degree of cross-linking of the modified ethylene / α-olefin copolymer is lower than 65% by mass, the heat resistance and creep characteristics of the finally obtained product will deteriorate. From this viewpoint, the gel fraction of the modified ethylene / α-olefin copolymer of the present invention is preferably 68% by mass or more. On the other hand, since it is currently technically difficult to completely crosslink all molecules, the upper limit of the gel fraction of the modified ethylene / α-olefin copolymer of the present invention is usually 90% by mass or less.

The gel fraction measurement method specified in JIS K6769 and JXPA401 is measured using a pipe that has been subjected to cross-linking treatment in a pipe state after actual pipe molding, but in the present invention, for the sake of simplicity. , The gel fraction of the modified ethylene / α-olefin copolymer shall be measured by the following method.

<Method of measuring gel fraction of modified ethylene / α-olefin copolymer>
Add 0.05% by mass of dioctyl tin laurylate to the modified ethylene / α-olefin copolymer (actually, add dioctyl tin laurylate to linear low density polyethylene with MFR: 1 g / 10 minutes and density of 920 kg / m ³ ). A master batch added in an amount of 1% by mass was added), and after melt-kneading, a sheet extruded to a thickness of 0.5 mm at 210 ° C. was crosslinked in warm water at 80 ° C. for 24 hours, and the sample was cut into 1 mm squares. 0.5 g (sample mass is G1 (g)) was refluxed in 200 mesh wire mesh in xylene at 120 ° C. for 8 hours by soxley extraction, and then the boiling xylene insoluble matter remaining on the wire mesh was 10 Torr. The mass is concentrated by drying in a vacuum at 80 ° C. for 8 hours (the mass of the purified boiling xylene insoluble content is G2 (g)), and the mass is calculated by the following formula (4).
Gel fraction (%) = G2 (g) ÷ G1 (g) x 100 (4)

Further, the modified ethylene / α-olefin copolymer of the present invention has an appropriate content of units derived from the unsaturated silane compound, and the gel fraction and MFR as a mixture are within the above-mentioned specified ranges. A blend of two or more modified ethylene / α-olefin copolymers, or a blend of a modified ethylene / α-olefin copolymer and an unmodified ethylene / α-olefin copolymer. May be good.

[Silane cross-linked ethylene / α-olefin copolymer]
The modified ethylene / α-olefin copolymer of the present invention constitutes the tubular body of the present invention as a silane crosslinked ethylene / α-olefin copolymer formed by a crosslinking reaction in the presence of a crosslinking catalyst.

<Crosslink catalyst>
As the cross-linking catalyst used for the cross-linking reaction of the modified ethylene / α-olefin copolymer, a silanol condensation catalyst is preferably used. Hereinafter, the silanol condensation catalyst will be described in detail.

Examples of the silanol condensation catalyst include tin catalysts such as dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctate, and dioctyltin dilaurate; lead catalysts such as lead naphthenate and lead stearate; zinc caprylate, Zinc catalysts such as zinc stearate; cobalt catalysts such as cobalt naphthenate, titanium catalysts such as tetrabutyl ester titanate; cadmium catalysts such as cadmium stearate; organics such as alkaline earth metal catalysts such as barium stearate and calcium stearate. Examples include metal catalysts. Of these, tin catalysts are preferred. One of these silanol condensation catalysts may be used alone, or two or more of them may be used in combination in any combination.

The amount of the silanol condensation catalyst added is usually 0.01% by mass or more, preferably 0.02% by mass or more, more preferably 0.02% by mass or more, based on the total mass of the modified ethylene / α-olefin copolymer to which the silanol condensation catalyst is added. It is 0.05% by mass or more, usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If the amount of silanol condensation catalyst added is too small, the cross-linking reaction will not proceed sufficiently, and if it is too large, it will be cost-effective.

It is generally convenient to add the silanol condensation catalyst in the form of a masterbatch. A masterbatch of a silanol condensation catalyst is produced, for example, by adding a silanol condensation catalyst to one or more polyolefins such as an ethylene homopolymer (polyethylene) and an ethylene / α-olefin copolymer and kneading them. be able to.

When the silanol condensation catalyst is used as a masterbatch in which a silanol condensation catalyst is mixed with polyolefin, the content of the silanol condensation catalyst in the masterbatch is not particularly limited, but is usually about 0.1 to 5.0% by mass. Is preferable.

If necessary, other miscible thermoplastic resins, stabilizers, lubricants, fillers, colorants, foaming agents, and other auxiliary materials can be added to the silanol condensation catalyst-containing masterbatch. These additives may be those that are known and commonly used in their own right. It is also possible to add these additives together with the silanol condensation catalyst as the third component to the modified ethylene / α-olefin copolymer of the present invention.

<Conditions for cross-linking agent reaction>
The cross-linking reaction using a silanol condensation catalyst is usually carried out in a water atmosphere after molding a composition obtained by blending a modified ethylene / α-olefin copolymer with a silanol condensation catalyst by various molding methods such as extrusion molding, injection molding and press molding. By exposing to, the cross-linking reaction between silanol groups is allowed to proceed. 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 hydrolyzable alkoxy group derived from an unsaturated silane compound used for graft modification of an ethylene / α-olefin copolymer reacts with water and hydrolyzes in the presence of a silanol condensation catalyst to hydrolyze silanol. As the groups are formed and the silanol groups are further dehydrated and condensed, the reaction proceeds, and the modified ethylene / α-olefin copolymers are bonded to each other to form a silane crosslinked ethylene / α-olefin copolymer.

The rate of progress of the cross-linking 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 1 week. Particularly preferred conditions are a temperature range of 20 to 130 ° C. and a range of 1 hour to 160 hours. When using moist air, the relative humidity is selected from the range of 1-100%.

In order for the silane-crosslinked ethylene / α-olefin copolymer to exhibit excellent properties over a long period of time, the gel fraction (crosslinking degree) of the silane-crosslinked ethylene / α-olefin copolymer is 0% or more. It is preferably 1% or more, and more preferably 1% or more. For the gel fraction, change the graft ratio (modification amount) of the unsaturated silane compound of the modified ethylene / α-olefin copolymer, the type and blending amount of the silanol condensation catalyst, the conditions for crosslinking (temperature, time), etc. Can be adjusted by The upper limit of this gel fraction is not particularly limited, but is usually 90%. The method for measuring the gel fraction is as described above.

<Use>
The use of the silane crosslinked ethylene / α-olefin copolymer obtained by cross-linking the modified ethylene / α-olefin copolymer of the present invention as described above is not particularly limited, but the silane crosslinked ethylene / α-olefin copolymer according to the present invention is not particularly limited. The copolymer is useful as the tubular body of the present invention as follows. In addition, it can be suitably used as an automobile elastomer member, for example, an automobile glass run channel, a weather strip, a rubber hose, a wiper blade rubber, and an industrial rubber elastomer product, for example, a packing, a gasket, an anti-vibration rubber, and the like.

[Tubular body]
A tubular body made of a silane-crosslinked ethylene / α-olefin copolymer obtained by cross-linking the modified ethylene / α-olefin copolymer of the present invention in the presence of a cross-linking catalyst usually has a modified ethylene / α-olefin copolymer weight. The raw material obtained by mixing a cross-linking catalyst with the coalescence is melt-kneaded and extruded by a molding machine equipped with a cylindrical die in an extruder. As the tubular body, a pipe, a hose, or the like is preferable. Hereinafter, the case of a pipe as a tubular body will be described as an example.

The extruded pipe is wound into a roll and crosslinked under high temperature and high humidity or by passing hot water through the inside of the pipe. The cross-linking treatment time is usually 16 to 24 hours, and the forming and cross-linking treatment causes the pipe to shrink in a roll state. Therefore, when the pipe is pulled out from the roll-shaped raw fabric during construction, the pipe is pulled out in a wavy state with a curl. For this reason, it is necessary to bend the curl back during construction, and at this time, an unreasonable force is applied, which deteriorates mechanical properties such as creep performance and causes water leakage. As a countermeasure, there is a method of performing the cross-linking treatment in a linear state, but the cross-linking equipment becomes large, which greatly affects the cost. However, by using the modified ethylene / α-olefin copolymer of the present invention, , Such a problem is solved.

Therefore, the resulting pipe crosslinks the silane groups in the form of rolls in the presence of warm water or steam. The cross-linking conditions are determined in consideration of the gel fraction finally obtained.

The crosslinked pipe using the modified ethylene / α-olefin copolymer of the present invention is a high-quality pipe having reduced curl and excellent appearance and long-term durability. According to the present invention, such crosslinked pipes are used. Pipes can be manufactured with good yield.

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.

[Manufacturing Example 1]
Novatec HY430 manufactured by JPE (ethylene / n-butene copolymer, MFR (190 ° C., 2.16 kg): 0.8 g / 10 minutes, density: 956 kg / m ³ , proportion of ethylene as a constituent unit: 97% by mass, Ratio of n-butene: 3% by mass) (indicated as "PE1" in Table 1) and Q300F (propylene / ethylene copolymer, MFR (230 ° C., 2,16 kg)) manufactured by Lyodorlbasell: 0. 8 g / 10 minutes, density: 890 kg / m ³ , as a constituent unit, ethylene ratio: 35% by mass, propylene ratio: 65% by mass) (indicated as "PP1" in Table-1) is 90:10. The mixture was mixed by mass to obtain an ethylene / α-olefin copolymer mixture 1.

Table 1 shows the melting end points and the ethylene content index measured by the following methods for the ethylene / α-olefin copolymer mixture 1.

<End of melting>
Using a differential scanning calorimeter manufactured by Hitachi High-Tech Science Co., Ltd., trade name "DSC6220", the temperature of about 5 mg of the sample was raised from 20 ° C. to 200 ° C. at a heating rate of 100 ° C./min according to JIS K7121 (2010). After holding at 200 ° C. for 3 minutes, the temperature was lowered to -10 ° C at a cooling rate of 10 ° C./min, and then the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. (° C.) was calculated and used as the melting end point.

The melting end point measured for Novatec HY430 manufactured by JPE was 132 ° C.

<Ethylene content index of ethylene / α-olefin copolymer mixture>
The ethylene content index in the ethylene / α-olefin copolymer mixture was measured by an FT-IR (infrared spectroscopy) apparatus (FT / IR-610, manufactured by JASCO). At this time, the sample was pressed at 160 ° C. so as to have a film thickness of 100 μm, measured in the permeation mode under the following conditions, and calculated by the following method.
<Measurement conditions>
Number of integrations: 32
Disassembly: 4 cm ^-1
Scan speed: 2 mm / sec
<Calculation method>
The ethylene content index was calculated by the following formula.
Ethylene content index = (peak height derived from ethylene group of ethylene / α-olefin copolymer mixture)
/ (For the propylene group of the ethylene / α-olefin copolymer mixture
Sum of peak height derived from and peak height derived from methylene group)
The peak height derived from the ethylene group is the peak height in 700 to 750 cm ^-1 , and the peak height derived from the propylene group is the peak height in 2700 to 2900 cm ^-1 .

0.1 part by mass of di-t-butyl peroxide (denoted as "Pox" in Table-1) and vinyltrimethoxysilane (Table-) with respect to 100 parts by mass of this ethylene / α-olefin copolymer mixture 1. (Described as "Si" in 1) 2 parts by mass was added and mixed, and then kneaded and extruded at 230 ° C. with a twin-screw extruder to obtain a modified ethylene / α-olefin copolymer 1.
The MFR (JIS K7210, 190 ° C., 2.16 kg) and density of the obtained modified ethylene / α-olefin copolymer 1 were measured by the following method. The results are shown in Table-1.
The gel fraction of the modified ethylene / α-olefin copolymer 1 was measured by the method described above, and the results are shown in Table 1.

<MFR>
Measured at 190 ° C. and 2.16 kg load according to JIS K7210 (1999).

<Density>
In accordance with the JIS K7112 (1999) A method, a test piece having a thickness of 2 mm, a length of 40 mm, and a width of 15 mm formed by a slow cooling press was used, and the measurement was performed by an underwater substitution method.

[Manufacturing Example 2]
JPE Novatec HY430 (ethylene / n-butene copolymer, MFR (190 ° C, 2.16 kg): 0.8 g / 10 minutes, density: 956 kg / m ³ ) and Lyodorelbasell Q300F (both propylene and ethylene) The polymer, MFR (230 ° C., 2,16 kg): 0.8 g / 10 minutes, density: 890 kg / m ³ ) was mixed at a mass ratio of 80:20 to obtain an ethylene / α-olefin copolymer mixture 2. ..
Regarding the obtained ethylene / α-olefin copolymer mixture 2, the melting end point and the ethylene content index were measured as described above, and the results are shown in Table 1.

0.1 part by mass of di-t-butyl peroxide and 2 parts by mass of vinyl trimethoxysilane are added to 100 parts by mass of the ethylene / α-olefin copolymer 2 and mixed, and then a twin-screw extruder is used. Kneaded and extruded at 230 ° C. to obtain a modified ethylene / α-olefin copolymer 2.
The MFR (JIS K7210, 190 ° C., 2.16 kg), density and gel fraction of the obtained modified ethylene / α-olefin copolymer 2 were measured by the above-mentioned method. The results are shown in Table-1.

[Manufacturing Example 3]
Di-t-butyl with respect to 100 parts by mass of Novatec HY430 (ethylene / n-butene copolymer, MFR (190 ° C. 2.16 kg): 0.8 g / 10 minutes, density: 956 kg / m ³ ) manufactured by JPE. 0.1 parts by mass of peroxide and 2 parts by mass of vinyl trimethoxysilane were added and mixed, and then kneaded and extruded at 230 ° C. with a twin-screw extruder to obtain a modified ethylene / α-olefin copolymer 3.
The MFR (JIS K7210, 190 ° C., 2.16 kg), density and gel fraction of the obtained modified ethylene / α-olefin copolymer 3 were measured by the above-mentioned method. The results are shown in Table-1.

[Example 1]
Linear low-density polyethylene (MFR: 4 g / 10 min, density) containing silanol condensation catalyst masterbatch (1 mass% tin catalyst (dioctyl tin dilaurate)) with respect to 100 parts by mass of the modified ethylene / α-olefin copolymer 1. : 900 kg / m ³ ) Masterbatch) 5 parts by mass was dry-blended and supplied to a 40 mm single-screw extruder equipped with a pipe die having a die diameter of 17 mm and a core diameter of 13 mm to prepare an unbridged pipe. This pipe was cut out to a length of 2 m, fixed in a loop, and left at 95 ° C. for 16 hours for cross-linking in a steam tank to prepare a silane cross-linked pipe. Using this pipe, the pipe straightness was evaluated by the following method.

<Pipe straightness evaluation>
It was evaluated according to the following evaluation criteria.
◯: After being released from the jig, both ends are separated by 1 cm or more and returned to a straight state, and it is easy to bend back.
X: Even after being released from the jig, both ends of the pipe do not return and it is difficult to bend back.

Separately from the above pipe, in the same manner as above, with respect to 100 parts by mass of the modified ethylene / α-olefin copolymer 1, a linear low density containing a silanol condensation catalyst masterbatch (1 mass% tin catalyst (dioctyl tin dilaurate)). A test piece having a thickness of 2 mm, a length of 70 mm, and a width of 120 mm was injection-molded using a dry blend of 5 parts by mass of polyethylene (MFR: 4 g / 10 minutes, density: 900 kg / m ³ ), and this test was performed. The pieces were crosslinked under the following conditions and the shrinkage rate was measured.

<Shrinkage rate>
Using a test piece having a thickness of 2 mm, a length of 70 mm, and a width of 120 mm, the dimensions (width) immediately after molding (before the cross-linking treatment) and after the cross-linking treatment at 85 ° C. and 85% for 16 hours were measured, and the shrinkage rate was calculated as follows. It was calculated by the formula (5).
Shrinkage rate = {(dimensions before cross-linking-dimensions after cross-linking) / dimensions before cross-linking} x 100
(5)

Based on the evaluation results of the pipe straightness evaluation and the measurement results of the shrinkage rate, a comprehensive evaluation was performed according to the following criteria.
<Comprehensive evaluation>
⊚: Pipe straightness evaluation is “○” and shrinkage rate is less than 4.2% Δ: Pipe straightness evaluation is “×” or shrinkage rate is 4.2% or more ×: Pipe straightness evaluation is “×” And the shrinkage rate is 4.2% or more

These results are shown in Table-1.

[Example 2]
A crosslinked pipe and a test piece were prepared in the same manner as in Example 1 except that the modified ethylene / α-olefin copolymer 2 was used instead of the modified ethylene / α-olefin copolymer 1, and evaluated in the same manner. went. The results are shown in Table-1.

[Comparative Example 1]
A crosslinked pipe and a test piece were prepared in the same manner as in Example 1 except that the modified ethylene / α-olefin copolymer 3 was used instead of the modified ethylene / α-olefin copolymer 1, and evaluated in the same manner. went. The results are shown in Table-1.

From the above results, according to the modified ethylene / α-olefin copolymer of the present invention, bending back after production of the crosslinked pipe can be easily performed, the gel content is high, the appearance is excellent, and after construction. It can be seen that a crosslinked pipe having excellent long-term durability can be produced.

Claims (8)

It is composed of a silane crosslinked ethylene / α-olefin copolymer obtained by cross-linking a modified ethylene / α-olefin copolymer obtained by graft-modifying an ethylene / α-olefin copolymer with an unsaturated silane compound in the presence of a cross-linking catalyst. A tubular body in which the modified ethylene / α-olefin copolymer satisfies the following (1) to (3).
(1) Α-olefin as a constituent unit contains propylene (2) Gel fraction is 65% by mass or more (3) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min to 2 g. / 10 minutes The tubular product according to claim 1, wherein the ethylene / α-olefin copolymer is a mixture containing an ethylene / propylene copolymer and an ethylene / α-olefin copolymer other than the ethylene / propylene copolymer. .. The tubular body according to claim 2, wherein the ethylene content index measured and calculated by the following method for the ethylene / α-olefin copolymer mixture is 0.10 to 0.95.
<Measurement / calculation method of ethylene content index of ethylene / α-olefin copolymer mixture>
A sheet of an ethylene / α-olefin copolymer mixture having a film thickness of 100 μm was subjected to FT-IR measurement in a transmission mode under the following measurement conditions, and calculated by the following calculation method.
<Measurement conditions>
Number of integrations: 32
Disassembly: 4 cm ^-1
Scan speed: 2 mm / sec
<Calculation method>
Ethylene content index = (peak height derived from ethylene group of ethylene / α-olefin copolymer mixture)
/ (For the propylene group of the ethylene / α-olefin copolymer mixture
Sum of peak height derived from and peak height derived from methylene group) The tubular body according to any one of claims 1 to 3, wherein the end peak temperature of melting measured by a differential scanning calorimeter (DSC) of the ethylene / α-olefin copolymer is 160 ° C. or higher. The tubular body according to any one of claims 1 to 4, wherein the cross-linking catalyst is a silanol condensation catalyst. A pipe made of a tubular body according to any one of claims 1 to 5. A hose made of a tubular body according to any one of claims 1 to 5. A modified ethylene / α-olefin copolymer obtained by graft-modifying an ethylene / α-olefin copolymer containing an ethylene / propylene copolymer with an unsaturated silane compound, wherein the modified ethylene / α-olefin copolymer is as follows. A modified ethylene / α-olefin copolymer satisfying (1) to (3).
(1) Α-olefin as a constituent unit contains propylene (2) Gel fraction is 65% by mass or more (3) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min to 2 g. / 10 minutes