JP2017145300A - Modified polyethylene composition, molded body, and silane crosslinked polyethylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified polyethylene composition which is excellent in flowability and has low permanent deformation.SOLUTION: A modified polyethylene composition contains a component (A) and a component (B), and 0.1-45 pts.wt. of the component (B) with respect to 100 pts.wt. of the component (A). The component (A) is polyethylene containing modified polyethylene obtained by graft modification of an unsaturated silane compound. The component (B) is at least one block copolymer selected from the group consisting of a block copolymer having a polymer block P derived from a vinyl aromatic compound and a polymer block Q derived from conjugated diene and/or isobutylene, and a block copolymer obtained by hydrogenating the block copolymer.SELECTED DRAWING: None

Description

  The present invention relates to a modified polyethylene composition having excellent fluidity and low permanent set. Moreover, this invention relates to the molded object and silane crosslinked polyethylene using this modified polyethylene composition.

  In recent years, furniture using a three-dimensional network structure obtained by extruding a thermoplastic resin in a loop shape as a cushioning material such as a cushioning material, and bedding such as a pillow and a bed mat are becoming popular.

  This three-dimensional network structure is generally manufactured as follows. That is, a thermoplastic resin is melted in an extruder, and the melted resin is extruded from a die having a large number of holes to form a strand. A water tank is provided under the die. When the strands naturally flow down and land in the water tank, and the strands stay in the water, the resin is solidified by cooling with water, and a three-dimensional network having loop-like entanglements. A shaped structure is manufactured (for example, Patent Document 1). Patent Document 1 proposes an ethylene / α-olefin copolymer as a thermoplastic resin used for forming a three-dimensional network structure.

  In a cushioning material such as a bedding using a three-dimensional network structure made of a thermoplastic resin, deformation (sagging) occurs at a high temperature, and a part of the bedding is depressed or deformed. This is because the thermoplastic resin constituting the three-dimensional network structure flows or plastically deforms under a load at a high temperature, but the ethylene / α-olefin copolymer has a low melting point. Since the shape cannot be maintained above the melting point, this settling and depression are particularly problematic.

  The ethylene / α-olefin copolymer as disclosed in Patent Document 1 has insufficient heat resistance, and is stale at high temperatures (in the present invention, “settlement” means that the permanent set becomes high. .) Occurs. In order to improve such problems, Patent Document 2 discloses a modified ethylene / α-olefin copolymer obtained by grafting an ethylenically unsaturated silane compound to an ethylene / α-olefin copolymer.

International Publication No. 2012/035736 JP 2013-181117 A

  In the modified ethylene / α-olefin copolymer as described in Patent Document 2, the modified ethylene / α-olefin copolymer has been emphasized by the detailed study of the present inventor. In addition, the fluidity of the composition containing the silanol condensation catalyst is low, and the load on the extruder when producing the three-dimensional network structure is increased, and the workability is deteriorated. It has also been found that there is a problem that the melt tension of the resin increases in the die and the strand diameter increases. For this reason, when this modified ethylene / α-olefin copolymer is used, the production efficiency is deteriorated, the feel of the three-dimensional network structure is hardened, and it is subject to design restrictions that the weight cannot be reduced. Conceivable.

  The present invention has been made in view of the above circumstances, and improves the problem of lowering the fluidity of polyethylene due to modification, reduces the load on the extruder, and reduces the thin strand diameter without impairing the extrusion workability. A modified polyethylene composition capable of providing a silane-crosslinked polyethylene having a small compression set by improving heat resistance, which is a major problem, and a modified polyethylene composition An object is to provide a molded article using the product and a silane-crosslinked polyethylene.

  As a result of intensive studies to achieve the above object, the present inventors have found that the modified polyethylene composition obtained by blending a specific amount of a styrene block copolymer with a modified polyethylene graft-modified with an unsaturated silane compound, The present inventors have found that the problems can be solved and have completed the present invention. That is, the gist of the present invention is as follows [1] to [8].

[1] A modified polyethylene composition comprising the following component (A) and component (B), comprising 0.1 to 45 parts by weight of component (B) with respect to 100 parts by weight of component (A).
Component (A): Polyethylene component containing a modified polyethylene graft-modified with an unsaturated silane compound (B): Polymer block P derived from vinyl aromatic compound and polymer block Q derived from conjugated diene and / or isobutylene And at least one block copolymer selected from the group consisting of block copolymers obtained by hydrogenating the block copolymer

[2] The modified polyethylene composition according to [1], wherein the unsaturated silane compound is a compound represented by the following formula (1).
RSi (R ′) ₃ (1)
(However, R is an ethylenically unsaturated hydrocarbon group, R 'is mutually independently a C1-C10 hydrocarbon group or a C1-C10 alkoxy group, and is at least 1 of R'. Is an alkoxy group having 1 to 10 carbon atoms.)

[3] The modified polyethylene composition according to [1] or [2], wherein the density of polyethylene used as a raw material for graft modification in the component (A) is 0.850 to 0.940 g / cm ³ .

[4] The modified polyethylene composition according to any one of [1] to [3], wherein the polyethylene used as a raw material for graft modification in the component (A) is an ethylene / α-olefin copolymer.

[5] The composition according to any one of [1] to [4], further comprising the following component (C) and having a content of 0.1 to 50 parts by weight with respect to 100 parts by weight of the component (A): Modified polyethylene composition.
Component (C): Hydrocarbon softener

[6] The modified polyethylene composition according to any one of [1] to [5], further including a silanol condensation catalyst.

[7] A molded article obtained by molding the modified polyethylene composition according to any one of [1] to [6].

[8] A silane-crosslinked polyethylene obtained by crosslinking the modified polyethylene composition according to [6].

  According to the present invention, there are provided a modified polyethylene composition having excellent fluidity and low permanent set, a molded article obtained using the same, and a silane-crosslinked polyolefin. Furthermore, since the modified polyethylene composition of the present invention, a molded product obtained using the same, and a silane-crosslinked polyolefin can prevent poor appearance of the product and hard cushioning due to a decrease in fluidity, it has a three-dimensional appearance. A network structure can be produced efficiently and with a high yield, and a three-dimensional network structure having a good feel can be provided.

  Embodiments of the present invention will be described in detail below, but the following description is an example of the embodiments of the present invention, and the present invention is limited to the following description unless it exceeds the gist. is not.

[Modified polyethylene composition]
The modified polyethylene composition of the present invention contains the following component (A) and component (B), and contains 0.1 to 45 parts by weight of component (B) with respect to 100 parts by weight of component (A).
Component (A): Modified polyethylene component obtained by graft-modifying an unsaturated silane compound on polyethylene component (B): Polymer block P derived from vinyl aromatic compound, and polymer block Q derived from conjugated diene and / or isobutylene And at least one block copolymer selected from the group consisting of block copolymers obtained by hydrogenating the block copolymer

  The modified polyethylene composition of the present invention is excellent in fluidity and has the effect of reducing permanent distortion. This effect is obtained, for example, in the case of only the component (A), in which the fluidity is low and the strands are thick, resulting in a hard cushioning three-dimensional network structure. By blending, the component (A) and the component (B) are phase-separated, which is considered to be an effect of reducing permanent distortion. Further, as described later, the modified polyethylene composition of the present invention preferably further contains a component (C). In such a case, since the melt viscosity is lowered, it is considered that the effect of improving fluidity is imparted. It is done.

[Component (A)]
Component (A) used in the present invention is a polyethylene containing a modified polyethylene obtained by graft-modifying an unsaturated silane compound.

  The polyethylene used as the raw material for graft modification of component (A) contains ethylene units as raw material monomers and has an ethylene unit content of 50% by weight or more based on the total amount of the structural units. The kind of polyethylene used as the raw material for graft modification of component (A) is not particularly limited as long as it is such, and known polyethylene is appropriately used.

  Specific examples of polyethylene used as a raw material for graft modification of component (A) include (branched or linear) ethylene homopolymers such as low, medium and high density polyethylene; ethylene-propylene copolymer, ethylene Ethylene / α-olefin copolymer such as -1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer; -Ethylene copolymer resins such as vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, and ethylene- (meth) acrylic acid ester copolymer. Furthermore, not only the said polymer can be used independently but 2 or more types of polymers can also be used in combination.

  Among these, in the present invention, high-pressure method low-density polyethylene, high-density polyethylene, and ethylene / α-olefin copolymer having an excellent balance between heat resistance and strength are preferable, and ethylene / α-olefin copolymer is more preferable. The ethylene / α-olefin copolymer is preferably a copolymer of 2 to 50% by weight of one or more α-olefins and 50 to 98% by weight of ethylene.

  The type of the catalyst used when producing polyethylene used as the raw material for graft modification of component (A) is not particularly limited, and examples thereof include a Ziegler-Natta catalyst and a metallocene catalyst. Among these, polyethylene produced by a metallocene catalyst is preferable.

The polyethylene used as the raw material for graft modification of component (A) has a density (measured according to JIS K6922-1, 2: 1997), preferably 0.850 to 0.940 g / cm ³ , preferably 0.860. ˜0.930 g / cm ³ , more preferably 0.880 to 0.920 g / cm ³ . When the density is not more than the above upper limit value, the thermal adhesiveness between the strands hardly deteriorates at the time of extrusion molding, and it tends to form a loop-shaped strand. If the density is equal to or higher than the above lower limit value, it tends to be difficult to fuse at the die outlet, and tends to form a loop-like strand, and tends to be excellent in durability, such as being difficult to sink as a three-dimensional network structure. .

  The melt flow rate (MFR) of polyethylene used as a raw material for graft modification of component (A) is a melt flow rate (MFR) measured under conditions of a temperature of 190 ° C. and a load of 2.16 kg in accordance with JIS K7210 (1999). And preferably 0.1 to 50 g / 10 min. If the MFR is too large, when a plurality of strands are extruded and molded, the strand loops are not stable, and the strand diameters are different for each strand, resulting in poor uniformity as a three-dimensional network structure. Performance and quality may be reduced. If the MFR is too small, the motor load during extrusion molding is large, the resin pressure increases, the strand diameter increases, and the strand surface may be roughened. From these viewpoints, the MFR of polyethylene is more preferably 1 g / 10 min or more, still more preferably 2 g / 10 min or more, while more preferably 40 g / 10 min or less, still more preferably 30 g / min. 10 minutes or less.

  In the present invention, polyethylene used as a raw material for graft modification of component (A) can be obtained as a commercial product. For example, “Engage (registered trademark)” series manufactured by DuPont Dow Elastomer Co., “Kernel (registered trademark)” series manufactured by Nippon Polyethylene Co., Ltd., “Engage (registered trademark)” series manufactured by Dow Dupont Elastomer Co., Ltd. (Registered trademark) "series, Mitsui Chemicals'" Evolue (trademark registered) "series, Tosoh Corporation" LUMITAC (registered trademark), Nipolon (registered trademark) "series and the like can be selected and used.

In component (A), the unsaturated silane compound used for graft modification of polyethylene is not limited, but an unsaturated silane compound represented by the following formula (1) is preferably used.
RSi (R ′) ₃ (1)

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

  In the formula (1), R 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 include alkenyl groups such as vinyl group, propenyl group, butenyl group, and cyclohexenyl group.

  In the formula (1), R ′ is preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms or 1 to 4 carbon atoms. Of the alkoxy group. Further, at least one of R ′ is preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms. The hydrocarbon group having 1 to 10 carbon atoms of R ′ may be any of an aliphatic group, an alicyclic group, and an aromatic group, but is preferably an aliphatic group. In addition, the alkoxy group having 1 to 10 carbon atoms of R ′ may be linear, branched or cyclic, but is preferably linear or branched. When R ′ is a hydrocarbon group, specifically, an alkyl group represented by methyl group, ethyl group, isopropyl group, t-butyl group, n-butyl group, i-butyl group, cyclohexyl group, etc., or phenyl An aryl group typified by a group and the like can be mentioned. When R ′ is an alkoxy group, specific examples include a methoxy group, an ethoxy group, an isopropoxy group, and a β-methoxyethoxy group.

  When the unsaturated silane compound is represented by the formula (1), at least one of the three R ′ is an alkoxy group, it is preferable that two R ′ are alkoxy groups, and all R ′ are More preferably, it is an alkoxy group.

  As the unsaturated silane compound, among the compounds represented by the formula (1), vinyltrialkoxysilanes represented by vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane and the like are desirable. This is because the vinyl group enables modification to polyethylene, and the alkoxy group promotes the crosslinking reaction described later. In other words, an alkoxy group introduced by graft-modifying to a modified polyethylene with an unsaturated silane compound reacts with water in the presence of a silanol condensation catalyst to hydrolyze to form a silanol group, and the silanol groups dehydrate and condense with each other. As a result, the modified polyethylenes are bonded to each other to cause a crosslinking reaction. In addition, these unsaturated silane compounds may be used individually by 1 type, and may use 2 or more types together.

  In the component (A), the modified polyethylene preferably has a modified amount of the unsaturated silane compound (amount of unsaturated silane compound introduced into the modified polyethylene by graft modification) of 0.1 to 5% by weight. When the amount of modification is not less than the above lower limit value, the heat resistance tends to be good, and this is preferable because the three-dimensional network structure is less likely to be deformed. Further, it is preferable that the amount of modification is not more than the above upper limit value because the viscosity does not become too high, the strand diameter at the time of extrusion molding becomes an appropriate thickness, and surface roughness is less likely to occur. From the viewpoint of making these better, the amount of modification of the unsaturated silane compound is more preferably 0.2% by weight or more, still more preferably 0.3% by weight or more, while more preferably 5%. 0.0% by weight or less, more preferably 3.0% by weight or less. The amount of modification of the unsaturated silane compound is the weight ratio of the unsaturated silane compound introduced by graft modification to ethylene before modification, and the sample is burned by heating to ash, and the ash is alkali-melted into pure water. It can be quantified after dissolution and confirmed by ICP emission spectrometry using a high frequency plasma emission spectrometer.

  The modified polyethylene in component (A) 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 compounds other than unsaturated silane compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid. Examples thereof include acids and acid anhydrides thereof.

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

  In general, graft modification of an unsaturated silane compound to polyethylene is performed 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 thereto. As a generation source of the carbon radical, in addition to the above-described electron beam and ionizing radiation, a high temperature method 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.

  There are no limitations on the radical generator used in producing the modified polyethylene. For example, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters and organic peroxides contained in ketone peroxide groups, and azo Compounds and the like.

  Specifically, for example, the hydroperoxide group includes cumene hydroperoxide, tertiary butyl hydroperoxide, and the like, and the dialkyl peroxide group includes dicumyl peroxide, ditertiary butyl peroxide, 2,5- Dimethyl-2,5-ditertiary butyl peroxyhexane, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexine-3 and the like are included, and the diacyl peroxide group includes lauryl peroxide and benzoyl peroxide. Etc. are included. The peroxyester group includes tertiary peroxyacetate, tertiary butyl peroxybenzoate, tertiary butyl peroxyisopropyl carbonate, and the like, and the ketone peroxide group includes cyclohexanone peroxide and the like. Examples of the azo compound include azobisisobutyronitrile and methyl azoisobutyrate. These radical generators may be used alone or in combination of two or more.

  As an operation of melt extrusion modification generally used, the above polyethylene, unsaturated silane compound, and organic peroxide are blended, blended and put into a kneader or extruder, and extruded while being heated and melt-kneaded. The molten resin emerging from the tip die is cooled in a water tank or the like to obtain a modified polyethylene.

  Although there is no restriction | limiting in particular as a mixing | blending ratio of polyethylene and an unsaturated silane compound, As a preferable mixing | blending range, an unsaturated silane compound is 1-10 weight part with respect to 100 weight part of polyethylene. If the amount of the unsaturated silane compound is too small relative to the polyethylene, the predetermined amount of modification necessary for obtaining the effects of the present invention may not be obtained. If the amount is too large, a large amount of unreacted unsaturated silane compound remains. However, the performance may be adversely affected.

  Although there is no restriction | limiting in particular as a mixing | blending ratio of an unsaturated silane compound and an organic peroxide, As a preferable mixing | blending range, an organic peroxide is 1-10 weight part with respect to 100 weight part of unsaturated silane compounds. is there. When the amount of the organic peroxide relative to the unsaturated silane compound is equal to or higher than the lower limit, a sufficient amount of radicals are generated and a necessary predetermined modification amount is easily obtained, and is equal to or lower than the upper limit. It tends to be easy to suppress deterioration of polyethylene.

  Moreover, as melt extrusion modification | denaturation conditions, it is preferable to extrude at the temperature of about 150-300 degreeC, for example in a single screw extruder and a twin screw extruder.

  The component (A) modified polyethylene used in the present invention has a melt flow rate (MFR) measured at 190 ° C. and a load of 2.16 kg in accordance with JIS K7210 (1999), preferably 2 g / 10 min or more. Preferably it is 3 g / 10 minutes or more, More preferably, it is 5 g / 10 minutes or more, Preferably it is 100 g / 10 minutes or less, More preferably, it is 50 g / 10 minutes or less, More preferably, it is 25 g / 10 minutes or less. When the MFR is equal to or higher than the lower limit, the motor load and resin pressure during extrusion molding are unlikely to increase, the strand surface and the product appearance are less likely to be roughened, and the strand diameter is less likely to increase, making it easier to reduce the product weight. When the MFR is less than or equal to the above upper limit, when extruding a plurality of strands, the loops of the strands are easy to stabilize, the strand diameters are likely to be uniform, and the uniformity as a three-dimensional network structure is improved. Tend to improve performance and quality.

[Component (B)]
Component (B) used in the present invention comprises a block copolymer having a polymer block P derived from a vinyl aromatic compound and a polymer block Q derived from a conjugated diene and / or isobutylene, and the block copolymer. It is at least one block copolymer in the group consisting of block copolymers formed by hydrogenating (sometimes referred to as “styrene block copolymers”). The modified polyethylene composition of the present invention has the effect of reducing permanent distortion by blending the component (B).

  In the component (B), the vinyl aromatic compound of the monomer constituting the block P is not particularly limited, but styrene derivatives such as styrene and α-methylstyrene are preferable. Of these, styrene is the main component. The block P may contain a monomer other than the vinyl aromatic compound as a raw material.

  Examples of the monomer other than the vinyl aromatic compound include ethylene and α-olefin. Moreover, when the block P contains monomers other than the said vinyl aromatic compound as a raw material, the content is usually less than 50 weight%, Preferably it is 40 weight% or less. When the content of the monomer other than the vinyl aromatic compound is within this range, the heat resistance tends to be good, and the compression set tends to be lower.

  Although the conjugated diene of the monomer constituting the block Q is not particularly limited, it is preferable that the monomer is mainly composed of butadiene and / or isoprene. The block Q may contain a monomer other than the conjugated diene as a raw material. Here, “mainly” in the component (B) means that the content is 50% by weight or more.

  Examples of the monomer other than the conjugated diene include isobutylene and styrene. Moreover, when the block Q contains monomers other than the said conjugated diene as a raw material, the content is usually less than 50 weight%, Preferably it is 40 weight% or less. When the content of the monomer other than the conjugated diene is within this range, bleeding out tends to be suppressed.

The block copolymer of component (B) may be a hydrogenated block copolymer obtained by hydrogenating a block copolymer having the polymer block P and the polymer block Q. More specifically, it may be a hydrogenated block copolymer obtained by hydrogenating double bonds of the block copolymer block Q. The hydrogenation rate of block Q is not particularly limited, but is preferably 80 to 100% by weight, more preferably 90 to 100% by weight. By hydrogenating the block Q within the above range, the adhesive property of the resulting modified polyethylene composition tends to decrease and the elastic property tends to increase. The same applies to the case where the block P uses a diene component as a raw material. The hydrogenation rate can be measured by ¹³ C-NMR. The component (B) preferably has at least two polymer blocks P.

  When the conjugated diene monomer constituting the block Q is butadiene, the butadiene in the microstructure can take a 1,4-addition structure and a 1,2-addition structure. In particular, the block Q is a hydrogenated derivative. In the case where butadiene is mainly used, the 1,4-addition structure of butadiene in the block Q microstructure is preferably 20 to 100% by weight.

  When the conjugated diene of the monomer constituting the block Q is isoprene, the isoprene in the microstructure can take a 1,2-addition structure, a 1,4-addition structure, and a 3,4-addition structure. Similarly, in particular, when block Q is a hydrogenated derivative and block Q is composed of isoprene, the 1,4-addition structure of isoprene in the microstructure of block Q is 60 to 100% by weight. Is preferred.

  Further, when the block Q is a hydrogenated derivative and the conjugated diene monomer constituting the block Q contains butadiene and isoprene, the 1,4-addition structure of butadiene and isoprene in the microstructure of the block Q is These are preferably 20 to 100% by weight and 60 to 100% by weight, respectively.

In any case, by setting the ratio of the 1,4-addition structure within the above range, the adhesive property of the resulting modified polyethylene composition tends to decrease and the elastic property tends to increase. The ratio of 1,4-addition structure (hereinafter sometimes referred to as “1,4-microstructure ratio”) can be measured by ¹³ C-NMR.

  Component (B) in the present invention is not particularly limited as long as it has a structure having at least two polymer blocks P and at least one polymer block Q, and may be any of linear, branched, radial, etc. However, the block copolymer represented by the following formula (2) or (3) is preferable. Furthermore, the block copolymer represented by the following formula (2) or (3) is more preferably a hydrogenated block copolymer obtained by hydrogenation. When the copolymer represented by the following formula (2) or (3) is a hydrogenated block copolymer, the thermal stability is improved.

P- (Q-P) m (2)
(PQ) n (3)
(In the formula, P represents a polymer block P, Q represents a polymer block Q, m represents an integer of 1 to 5, and n represents an integer of 2 to 5.)

  In formula (2) or (3), m and n are preferably larger in terms of lowering the order-disorder transition temperature as a rubbery polymer, but smaller in terms of ease of production and cost. Good.

  When component (B) is a hydrogenated block copolymer represented by formula (2) or (3) and block Q is composed of butadiene, 1,4-addition of butadiene in the microstructure of block Q The structure is preferably 20 to 100% by weight. Similarly, when the block Q is composed of isoprene, the 1,4-addition structure of isoprene in the microstructure of the block Q is preferably 60 to 100% by weight. Similarly, when the block Q is composed of butadiene and isoprene, the 1,4-addition structure of butadiene and isoprene in the microstructure of the block Q may be 20 to 100% by weight and 60 to 100% by weight, respectively. preferable. In any case, by setting the 1,4-microstructure ratio within the above range, the adhesive property of the resulting modified polyethylene composition tends to be lowered and the elastic property tends to be increased.

  The block copolymer and / or hydrogenated block copolymer (hereinafter sometimes referred to as “(hydrogenated) block copolymer”) is represented by the formula (3) because of its excellent rubber elasticity. The (hydrogenated) block copolymer represented by the formula (2) is more preferable than the (hydrogenated) block copolymer, and the (hydrogenated) block represented by the formula (2) in which m is 3 or less. A copolymer is more preferred, and a (hydrogenated) block copolymer represented by the formula (2) in which m is 2 or less is more preferred, and a formula (2) in which m is 1 (hydrogenated). A block copolymer is most preferred.

  The weight ratio of the block P and the block Q constituting the component (B) is arbitrary, but from the viewpoint of the mechanical strength and heat fusion strength of the modified polyethylene composition of the present invention, it is preferable that the block P is large. On the other hand, it is preferable that the number of blocks P is small in terms of flexibility, profile extrusion formability, and bleed-out suppression.

  The weight ratio of the block P in the component (B) is preferably 5% by weight or more, more preferably 10% by weight or more, and preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably The amount is 50% by weight or less, and particularly preferably 40% by weight or less.

  The styrene content in component (B) is preferably 5% by weight or more, more preferably 10% by weight or more, preferably 70% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight. % Or less, particularly preferably 40% by weight or less.

  The method for producing the component (B) in the present invention is not particularly limited as long as the above structure and physical properties can be obtained. Specifically, for example, it can be obtained by performing block polymerization in an inert solvent using a lithium catalyst or the like by the method described in Japanese Patent Publication No. 40-23798. The block copolymer may be hydrogenated (hydrogenated), for example, as described in JP-B-42-8704, JP-B-43-6636, JP-A-59-133203, and JP-A-60-79005. Can be carried out in an inert solvent in the presence of a hydrogenation catalyst. In this hydrogenation treatment, 50% or more of the olefinic double bonds in the polymer block are preferably hydrogenated, more preferably 80% or more are hydrogenated, and in the polymer block It is preferable that 25% or less of the aromatic unsaturated bond is hydrogenated.

  The number average molecular weight (Mn) of the block copolymer of the component (B) in the present invention is not particularly limited, but is preferably 30,000 or more, more preferably 50,000 or more, further preferably 80,000 or more, Moreover, Preferably it is 500,000 or less, More preferably, it is 400,000 or less, More preferably, it is 300,000 or less. When the number average molecular weight of the component (B) is within the above range, moldability and heat resistance tend to be good.

  The weight average molecular weight (Mw) of the block copolymer of component (B) is not particularly limited, but is preferably 50,000 or more, more preferably 80,000 or more, and further preferably 100,000 or more. , Preferably 550,000 or less, more preferably 500,000 or less, and still more preferably 400,000 or less. When the weight average molecular weight of the component (B) is within the above range, moldability and heat resistance tend to be good.

  In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the block copolymer of the component (B) are polystyrene conversion values determined by measurement by gel permeation chromatography (GPC), The measurement conditions are as follows.

(Measurement condition)
Equipment: “HLC-8120GPC” manufactured by Tosoh Corporation
Column: “TSKgel Super HM-M” manufactured by Tosoh Corporation
Detector: Differential refractive index detector (RI detector / built-in)
Solvent: Chloroform Temperature: 40 ° C
Flow rate: 0.5 mL / min Injection volume: 20 μL
Concentration: 0.1% by weight
Calibration data: Monodisperse polystyrene Calibration method: Polystyrene conversion

  The block copolymer of component (B) can be obtained as a commercial product. Examples of commercially available products include hydrogenated block copolymers such as “Clayton (registered trademark) -G” series manufactured by Kraton Polymer Co., Ltd., “Septon (registered trademark)” series manufactured by Kuraray Co., Ltd., and “Hibler (registered trademark)”. ) ”Series,“ Tough Tech (registered trademark) ”series manufactured by Asahi Kasei Corporation, and the like. Commercially available non-hydrogenated block copolymers include “Clayton (registered trademark) -A” series manufactured by Kraton Polymer Co., Ltd., “Hibler (registered trademark)” series manufactured by Kuraray Co., Ltd. Registered trademark) "series and the like.

  The modified polyethylene composition of the present invention contains 0.1 to 45 parts by weight of component (B) with respect to 100 parts by weight of component (A). By making content of a component (B) into the said range, fluidity | liquidity is favorable and permanent set becomes low. From these viewpoints, the content of the component (B) is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, preferably 40 parts by weight with respect to 100 parts by weight of the component (A). The amount is at most 35 parts by weight, more preferably at most 35 parts by weight.

[Component (C)]
Component (C) used in the present invention is a hydrocarbon rubber softener. Component (C) softens the modified polyethylene composition and contributes to improvement in flexibility, elasticity, workability, fluidity, and permanent set reduction.

  Examples of the hydrocarbon rubber softener include mineral oil softeners and synthetic resin softeners, and mineral oil softeners are preferable from the viewpoint of affinity with other components. Mineral oil softeners are generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, with paraffinic oils in which 50% or more of all carbon atoms are paraffinic hydrocarbons, Those in which 30 to 45% of all carbon atoms are naphthenic hydrocarbons are called naphthenic oils, and those in which 35% or more of all carbon atoms are aromatic hydrocarbons are called aromatic oils. Of these, paraffinic oil is preferably used in the present invention. In addition, the hydrocarbon rubber softening agent may be used alone, or two or more may be used in any combination and ratio.

  The kinematic viscosity at 40 ° C. of the hydrocarbon rubber softener of component (C) is not particularly limited, but is preferably 20 centistokes or more, more preferably 50 centistokes or more, and preferably 800 centistokes or less. More preferably, it is 600 centistokes or less. The flash point (COC method) of the hydrocarbon rubber softener is preferably 200 ° C. or higher, more preferably 250 ° C. or higher.

  Component (C), a hydrocarbon rubber softener, can be obtained as a commercial product. Examples of the commercially available products include “Nisseki Polybutene (registered trademark) HV” series manufactured by JX Nippon Oil & Energy Corporation, Diana (registered trademark) “Process Oil PW” series manufactured by Idemitsu Kosan Co., Ltd., etc. Appropriate products can be selected and used from among them.

  The modified polyethylene composition of the present invention preferably contains 0.1 to 50 parts by weight of component (C) with respect to 100 parts by weight of component (A). By making content of a component (C) into the said range, fluidity | liquidity is further favorable and permanent set becomes low. From these viewpoints, the content of the component (C) with respect to 100 parts by weight of the component (A) is more preferably 0.5 parts by weight or more, still more preferably 0.1 parts by weight or more, More preferred is 40 parts by weight or less, still more preferred is 30 parts by weight or less, and particularly preferred is 20 parts by weight or less.

[Silanol condensation catalyst]
By blending the silanol condensation catalyst with the modified polyethylene composition of the present invention, the modified polyethylene in the modified polyethylene composition can be cross-linked between molecules.

  The silanol condensation catalyst that can be used in the present invention is selected from the group consisting of metal organic acid salts, titanates, borates, organic amines, ammonium salts, phosphonium salts, inorganic acids and organic acids, and inorganic acid esters. One or more compounds may be mentioned.

  Examples of metal organic acid salts include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, cobalt naphthenate, lead octylate, lead naphthenate, octylic acid Examples include zinc, zinc caprylate, iron 2-ethylhexanoate, iron octylate, and iron stearate. Examples of titanates include tetrabutyl titanate, tetranonyl titanate, bis (acetylacetonitrile) di-isopropyl titanate, and the like. Examples of the organic amine include ethylamine, dibutylamine, hexylamine, triethanolamine, dimethyl soyaamine, tetramethylguanidine, pyridine and the like. Examples of the ammonium salt include ammonium carbonate and tetramethylammonium hydroxide. Examples of the phosphonium salt include tetramethylphosphonium hydroxide. Examples of the inorganic acid and the organic acid include sulfonic acids such as sulfuric acid, hydrochloric acid, acetic acid, stearic acid, maleic acid, toluenesulfonic acid, and alkylnaphthylsulfonic acid. Examples of inorganic acid esters include phosphate esters.

Of these, metal organic acid salts, sulfonic acids, and phosphoric acid esters are preferred, and tin metal carboxylates such as dioctyl tin dilaurate, alkyl naphthyl sulfonic acids, and ethylhexyl phosphoric acid esters are more preferred.
In addition, the silanol condensation catalyst mentioned above may be used alone or in combination of two or more.

  The blending amount of the silanol condensation catalyst is not particularly limited, but is preferably 0.0001 to 0.01 parts by weight, more preferably 0.0001 to 0.005 parts by weight with respect to 100 parts by weight of the modified polyethylene. Part. If the blending amount of the silanol condensation catalyst is not less than the above lower limit value, it is preferable because the crosslinking reaction proceeds sufficiently and the heat resistance tends to be good, and if it is not more than the above upper limit value, early crosslinking is unlikely to occur in the extruder. It is preferable because the surface of the strand and the appearance of the product tend not to be rough.

  The silanol condensation catalyst is preferably used as a master batch in which a polyolefin and a silanol condensation catalyst are blended. Examples of the polyolefin that can be used in the master batch include polyethylene, polypropylene, and propylene-ethylene copolymer.

  Examples of polyethylene include (branched or linear) ethylene homopolymers such as low, medium and high density polyethylene; ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 4-methyl- 1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene / α-olefin copolymer such as ethylene / 1-octene copolymer; ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid Examples thereof include ethylene copolymers such as copolymers and ethylene / (meth) acrylic acid ester copolymers. Among these, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer, etc. The ethylene / α-olefin copolymer is preferred. Examples of polypropylene include random polypropylene, block polypropylene, and homopolypropylene.

  In the master batch of the silanol condensation catalyst, only one kind of these polyolefins may be used, or two or more kinds may be blended and used.

  When the silanol condensation catalyst is used as a master batch in which a polyolefin and a silanol condensation catalyst are blended, the content of the silanol condensation catalyst in the master batch is not particularly limited, but is usually about 0.1 to 5.0% by weight. It is preferable to do.

  A commercially available product can be used as the silanol condensation catalyst-containing masterbatch, for example, “LZ082” manufactured by Mitsubishi Chemical Corporation.

[Other ingredients]
In addition to the component (A), the component (B), the component (C) used as necessary, and the silanol condensation catalyst, the modified polyethylene composition of the present invention includes various additives (however, the component (Except for those corresponding to (C)), resins other than the component (A) or the component (B), and the like can be contained within a range not impairing the effects of the present invention.

Examples of the additive include a thermal stabilizer, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a crystal nucleating agent, a rust inhibitor, a viscosity modifier, and a pigment. Among these, it is preferable to contain an antioxidant, particularly a phenol-based antioxidant, a sulfur-based antioxidant, or a phosphorus-based antioxidant. It is preferable to contain 0.1-1 weight part of antioxidant with respect to 100 weight part of modified polyethylene.

  Other resins include, for example, polyolefin resins (excluding those corresponding to component (A)), polyester resins, polycarbonate resins, polymethyl methacrylate resins, rosin and derivatives thereof, terpene resins and petroleum resins and derivatives thereof. Alkyd resin, alkylphenol resin, terpene phenol resin, coumarone indene resin, synthetic terpene resin, and alkylene resin.

[Method for producing modified polyethylene composition]
In the present invention, the modified polyethylene composition is obtained by combining a component (A), a component (B) component, a component (C) blended as necessary, other components and the like by a known method such as a Henschel mixer, a V blender. It can be produced by mechanically mixing with a tumbler blender or the like and then mechanically kneading and kneading by a known method. For this melt-kneading, a general melt-kneader such as a Banbury mixer, various kneaders, a single-screw or twin-screw extruder can be used. In addition, as shown in the Examples below, the modified polyethylene composition of the present invention is made of component (A) raw material such as polyethylene and unsaturated silane compound, component (B), and component blended as necessary. (C) You may manufacture by carrying out melt kneading | mixing with other components etc. to melt kneading machines, such as a Banbury mixer, various kneaders, a single screw or a twin screw extruder. That is, the graft modification for producing the component (A) and the melt kneading for producing the modified polyethylene composition may be performed simultaneously. When the modified polyethylene composition of the present invention is produced by kneading with a single-screw or twin-screw extruder or the like, the melt-kneading can usually be carried out in a state heated to 140 to 240 ° C, preferably 160 to 220 ° C.

[Silane-crosslinked polyethylene]
In the modified polyethylene composition of the present invention, the aforementioned silanol condensation catalyst is blended and molded by various molding methods such as extrusion molding, injection molding, press molding, etc., and then exposed to a water atmosphere to cause a crosslinking reaction between silanol groups. Proceed to silane-crosslinked polyethylene. Various conditions can be adopted for the method of exposure in a water atmosphere, a method of leaving in air containing moisture, a method of blowing air containing water vapor, a method of immersing in a water bath, and spraying hot water in a mist form And the like.

  In the modified polyethylene composition of the present invention, the hydrolyzable alkoxy group derived from the unsaturated silane compound used for the graft modification of polyethylene reacts with water in the presence of a silanol condensation catalyst and hydrolyzes to produce a silanol group. Further, silanol groups are dehydrated and condensed, whereby a crosslinking reaction proceeds, and modified polyethylenes are bonded to each other to produce a silane-crosslinked polyethylene.

  The rate of progress of the cross-linking reaction is determined by the conditions of exposure in a water atmosphere, but the exposure is usually in the temperature range of 20 to 130 ° C. and in the 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 air containing moisture is used, the relative humidity is selected from the range of 1 to 100%.

  In order for the silane-crosslinked polyethylene to exhibit excellent characteristics over a long period of time, the gel fraction (degree of crosslinking) of the silane-crosslinked polyethylene is preferably 20% or more, and more preferably 30% or more. The gel fraction can be adjusted by changing the graft ratio (modified amount) of the unsaturated silane compound of the modified polyethylene, the type and blending amount of the silanol condensation catalyst, and the conditions (temperature, time) for crosslinking. . The upper limit of the gel fraction is not particularly limited, but is usually 90%. The gel fraction can be measured by the method described in the Examples section below.

  The modified polyethylene composition of the present invention blended with a silanol condensation catalyst is extruded to form a strand, and then the strands are heat-sealed and then cooled with water to form a three-dimensional network structure. Can do. For example, the modified polyethylene composition can be formed into a three-dimensional network structure by a manufacturing apparatus and a forming method as described in International Publication No. 2012/035736. The three-dimensional network structure thus obtained is preferably exposed to a water atmosphere as described above and used as a silane-crosslinked polyethylene.

  In particular, since the modified polyethylene composition of the present invention can be molded without being crosslinked at the time of molding, a three-dimensional network structure requiring special moldability such as strand diameter immediately after molding, loop property, thermal adhesiveness and the like. The resulting molded product has improved heat resistance, which is a major issue with polyethylene such as ethylene / α-olefin copolymers, so that it can be used even under high-temperature loads. Therefore, it is possible to provide a three-dimensional network structure having excellent cushioning properties.

[Use]
The use of the modified polyethylene composition and silane-crosslinked polyethylene of the present invention is not particularly limited, but can be suitably used as a cushioning material for furniture, bed mats, bedding such as pillows; vehicle seats for vehicles, ships, and the like. . In addition, when applied to these uses, it is preferably used as the aforementioned three-dimensional network structure. This three-dimensional network structure can also be used as a laminate with other materials as required. However, the molded body of the present invention is not limited to a three-dimensional network structure.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example, unless the summary is exceeded. Further, 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 range is the above-described upper limit or lower limit value. A range defined by a combination of values of the following examples or values of the examples may be used.

〔material〕
In the examples and comparative examples of the present invention, the following raw materials were used.

<Raw material polyethylene of component (A)>
PE-1: Kernel (registered trademark) KS571 (manufactured by Nippon Polyethylene, metallocene linear low density polyethylene, MFR: 13 g / 10 min (190 ° C., load 2.16 kg), density: 0.907 g / cm ³ )
PE-2: LUMITAC (registered trademark) 54-1 (manufactured by Tosoh Corporation, linear ultra-low density polyethylene, MFR: 20 g / 10 min (190 ° C., load 2.16 kg), density: 0.910 g / cm ³ )
<Component (B)>
SBC-1: Kraton G (registered trademark) G1650 (manufactured by Kraton Polymer Co., Ltd., hydrogenated product of styrene / ethylene / butadiene / styrene block copolymer, styrene content: 30% by weight, hydrogenation rate of butadiene: 100% by weight 1,4-microstructure ratio: 100% by weight, number average molecular weight (Mn) 82,000, weight average molecular weight (Mw): 91,000, solution viscosity: 8.0 Pa · s (polymer concentration 25%, 25 ° C. Toluene solution))
SBC-2: Kraton G (registered trademark) G1651 (manufactured by Kraton Polymer Co., Ltd., hydrogenated styrene / ethylene / butadiene / styrene block copolymer, styrene content: 13 wt%, butadiene hydrogenation rate: 100 wt% 1,4-microstructure ratio: 100% by weight, number average molecular weight (Mn) 220,000, weight average molecular weight (Mw): 260,000, solution viscosity: 8.0 Pa · s (polymer concentration 10%, 25 ° C. Toluene solution))

<Ingredient (C)>
Process oil: Diana (registered trademark) process oil PW90 (manufactured by Idemitsu Kosan Co., Ltd., petroleum hydrocarbon, kinematic viscosity (40 ° C.): 90 centistokes, flash point (COC method): 266 ° C.)

<Catalyst masterbatch (MB)>
Catalyst MB: LZ082 (manufactured by Mitsubishi Chemical Corporation, tin catalyst (dioctyltin dilaurate) -containing linear low density polyethylene, MFR of low density polyethylene: 4 g / 10 min (190 ° C., load 2.16 kg), density of low density polyethylene : 0.900 g / cm ³ , melting peak temperature of low density polyethylene: 90 ° C.)

[Measurement and evaluation method]
The measurement and evaluation methods for various physical properties and characteristics are as follows.

<Measurement and evaluation of modified polyethylene composition>
[Melt flow rate (MFR)]
Based on JIS K7210 (1999), MFR of the modified polyethylene composition (polyethylene in Comparative Example 1 and modified polyethylene in Comparative Examples 2 and 3) was measured at 190 ° C. and a load of 2.16 kg.

[Modification amount]
The modified polyethylene composition (modified polyethylene in Comparative Examples 2 and 3) is heated to burn and ash, and the ash content is melted with alkali and dissolved in pure water, and then quantified. Using a high-frequency plasma emission analyzer (ICPS7510 manufactured by Shimadzu Corporation), ICI The amount of the unsaturated silane compound introduced into the polyethylene by graft modification was determined by emission spectrometry.

<Evaluation of silane-crosslinked polyethylene>
[Gel fraction]
The weight percent of the insoluble matter after Soxhlet extraction at the xylene boiling point for 10 hours was measured.

[Compression set]
The manufactured sheet-like molded product is punched into a circular shape with a diameter of 30 mm, and six of these are stacked and compressed in accordance with JIS K6262 by 25% with a spacer for 24 hours at 23 ° C., then in Table 1 Heat treatment is performed at the indicated test temperature (20 ° C., 50 ° C. or 70 ° C.) for 24 hours, and after treatment, the sample is left in a constant temperature room at 23 ° C. for 30 minutes, and then compressed, the thickness is measured, and compression set (CS: Unit%) was calculated. A lower compression set value is better.

[Example 1]
100 parts by weight of PE-1 as polyethylene, 2.0 parts by weight of vinyltrimethoxysilane (VTMOS), 0.1 parts by weight of ditertiary butyl peroxide, 1 part by weight of SBC-1, and 1 part by weight of process oil Partly mixed and stirred with a blender. Thereafter, it is put into a twin screw extruder (PCM45, manufactured by Ikegai Co., Ltd.) set at a temperature of 200 ° C., and the strand coming out from the nozzle is cooled and solidified in a water tank, and then cut into a pellet to obtain a modified polyethylene composition. Got. Table 1 shows the physical properties of the resulting modified polyethylene composition.

  5 parts by weight of LZ082 was added as catalyst MB to 100 parts by weight of the modified polyethylene composition obtained above to obtain a modified polyethylene composition containing catalyst MB. This was molded by an injection molding machine at 200 ° C., and immersed in warm water at 80 ° C. for 24 hours to produce a sheet-like molded product having a thickness of 2 mm made of silane-crosslinked polyethylene. The gel fraction and compression set of the obtained silane-crosslinked polyethylene were evaluated. The results are shown in Table-1.

[Examples 2 to 5 and Comparative Examples 1 to 3]
A modified polyethylene composition and a silane-crosslinked polyethylene were produced in the same manner as in Example 1 except that the types and compositions of the raw materials used were changed as shown in Table-1. Various evaluations were also made. The results are shown in Table-1.

  The following can be seen from the above results. First, as shown in Examples 1 and 2, the modified polyethylene composition to which the styrene-based block copolymer of component (B) and the process oil of component (C) are added is that of Comparative Example 2 in which these are not blended. While maintaining compression set at 20 ° C. to 70 ° C. almost, all showed high MFR. Further, as in Example 3, in the modified polyethylene composition in which the addition amount of the styrene-based block copolymer of component (B) and the process oil of component (C) exceeds 10 parts by weight, Comparative Example 1 of unmodified polyethylene Further, the compression set at 20 ° C. to 70 ° C. was low and a good value. Since the modified polyethylene compositions of Examples 1 to 5 are excellent in fluidity, excellent moldability such as low resin pressure can be expected. In Examples 3, 4, and 5, the value of compression set in each temperature region was also good.

  On the other hand, as in Comparative Examples 2 and 3, when the styrene block copolymer of component (B) and the process oil of component (C) were not used, the MFR of the modified polyethylene was low and the fluidity was significantly reduced. Further, Comparative Examples 1 and 2 and Comparative Example 3 had larger values of compression set (20, 50, 70 ° C.) than Examples 3 and 4, 5 using the same polyethylene, respectively. .

  From the above, the modified polyethylene composition of the present invention using the component (B) styrenic block copolymer and the component (C) process oil has a high MFR and excellent fluidity. It can be seen that silane-crosslinked polyethylene with a small compression set can be produced.

  The modified polyethylene composition of the present invention can suppress a decrease in fluidity, reduce the load on the extruder, and can easily produce a lightweight three-dimensional network structure. Moreover, according to the modified polyethylene composition of the present invention, it is possible to provide a silane-crosslinked polyethylene that has a small compression set and is unlikely to cause depression or settling due to repeated use. For this reason, the modified polyethylene composition and silane-crosslinked polyethylene of the present invention can be suitably used as a constituent material for cushioning materials for furniture, bed mats, pillows, etc .; vehicles, and seats for ships.

Claims (8)

A modified polyethylene composition comprising the following component (A) and component (B), comprising 0.1 to 45 parts by weight of component (B) with respect to 100 parts by weight of component (A).
Component (A): Polyethylene component containing a modified polyethylene graft-modified with an unsaturated silane compound (B): Polymer block P derived from vinyl aromatic compound and polymer block Q derived from conjugated diene and / or isobutylene And at least one block copolymer selected from the group consisting of block copolymers obtained by hydrogenating the block copolymer The modified polyethylene composition according to claim 1, wherein the unsaturated silane compound is a compound represented by the following formula (1).
RSi (R ′) ₃ (1)
(However, R is an ethylenically unsaturated hydrocarbon group, R 'is mutually independently a C1-C10 hydrocarbon group or a C1-C10 alkoxy group, and is at least 1 of R'. Is an alkoxy group having 1 to 10 carbon atoms.) The modified polyethylene composition according to claim 1 or 2, wherein the density of polyethylene used as a raw material for graft modification in component (A) is 0.850 to 0.940 g / cm ³ .   The modified polyethylene composition according to any one of claims 1 to 3, wherein the polyethylene used as a raw material for graft modification in the component (A) is an ethylene / α-olefin copolymer. The modified polyethylene composition according to any one of claims 1 to 4, further comprising the following component (C) and having a content of 0.1 to 50 parts by weight with respect to 100 parts by weight of the component (A). object.
Component (C): Hydrocarbon softener   The modified polyethylene composition according to any one of claims 1 to 5, further comprising a silanol condensation catalyst.   The molded object formed by shape | molding the modified polyethylene composition of any one of Claims 1 thru | or 6.   Silane cross-linked polyethylene obtained by cross-linking reaction of the modified polyethylene composition according to claim 6.