JP2018162414A - Ethylenic resin composition for sheet and molded body of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high melt-tension ethylenic resin composition for sheet which is excellent in molding working characteristics and can be recycled, and to provide a molded body of the same.SOLUTION: An ethylenic resin composition for sheet contains 8-38 mass% of a specific ethylenic copolymer (A) and 62-92 mass% of specific polyethylene (B), and has the following characteristics (i) to (iv): characteristic (i): an MFR of 0.1-2 g/10 min; characteristic (ii): a bending elastic modulus at 23°C of 850 MPa or more; characteristic (iii): a melt tension at 180°C of 120 mN or more; and characteristic (iv): in a relationship between the melt tension (MT and unit: mN) measured at 180°C, 190°C and 220°C and the measurement temperature (t and unit:°C), a coefficient A (temperature dependency coefficient) of expression (1) approximated by a least square method of -0.010 or less. Expression (1): MT=a×e, in the expression (1), e is a base of natural logarithm (Napier's number), and a is a coefficient determination by approximation.SELECTED DRAWING: None

Description

  The present invention relates to an ethylene-based resin composition for a sheet and a molded article thereof. More specifically, the present invention can be molded in the same manner as general polyethylene at the time of sheet molding, and is extremely molten when vacuum molded into a product shape in a secondary processing step The present invention relates to an ethylene-based resin composition for a sheet and a molded body thereof, which have high tension and are unlikely to sag a raw sheet, can be molded into a large product, and can be recycled.

  Conventionally, sheet forming is divided into a sheet raw fabric manufacturing process and a thermal forming process by vacuum forming. In the sheet original manufacturing process, a good fluidity and a melt tension enough to take off the sheet are required, whereas a vacuum is required. In the molding process, the entire sheet is heated to a semi-molten state and pressed against the mold, so that a very high melt tension is required. The required level of melt tension at the time of vacuum forming becomes higher as the product becomes larger or the drawing at the time of forming becomes deeper.

  Generally, to increase the melt tension of polyethylene, the molecular weight is increased or a branched structure is developed. However, there is a limit to improving the melt tension by these methods. The load increases, the productivity decreases, and in some cases, extrusion cannot be performed. In addition, there is a technology to crosslink polyethylene by peroxide or electron beam irradiation, but in this case, the manufacturing process becomes complicated, or the cross-linked polyethylene is recycled due to its high molecular weight due to irreversible chemical reaction. This makes it difficult to use the scraps and the like generated at the time of manufacture, and there is a problem that the manufacturing cost is high.

For example, in Patent Document 1 (Patent No. 4955013), in order to modify the melting characteristics of a polyethylene resin, an ethylene copolymer resin powder is used at a temperature higher than the starting temperature of the organic free radical initiator and lower than the melting point of the ethylene copolymer. A technique for contacting with a specific amount of an organic free radical initiator is disclosed, and it is said that a modified resin having improved melt tension as compared with a conventional polyethylene resin is provided.
However, this technique using an organic free radical initiator is a technique for irreversibly cross-linking polyethylene resin, and the modified resin has a cross-linking point when it is recycled and generates a gel or has a large extrusion load. There is a possibility of becoming. That is, there is a high possibility that it cannot be recycled.

Japanese Patent No. 4955013

  In the circumstances as described above, the high melt tension ethylene system for sheet having moldability and recyclability that could not be achieved by the conventional polyethylene resin composition, eliminating the problems of the conventional ethylene resin composition There is a need for resin compositions.

  In view of the above-described problems of the prior art, an object of the present invention is to provide a high melt tension ethylene-based resin composition for a sheet that is excellent in moldability and can be recycled, and a molded body thereof.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have copolymerized ethylene with a specific radical polymerizable acid anhydride, and further reacted the copolymer with a polyhydric alcohol compound. Found that an ethylene-based resin composition obtained by blending a copolymer having a specific index with polyethylene having a specific index solves the above-mentioned problems and exhibits good characteristics, and based on these findings The present invention has been completed.

That is, the ethylene resin composition for a sheet of the present invention comprises a copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers, and a polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule. And an ethylene copolymer (A) having a melt flow rate (MFR) of 1 to 10 g / 10 min measured at a temperature of 190 ° C. and a load of 2.16 kg, containing 8 to 38 mass As well as 62 to 92% by mass of polyethylene (B) having an MFR of 0.1 to 2 g / 10 min and a density of 0.945 to 0.970 g / cm ³ , and the following characteristics (i) to (iv) It is characterized by having.
Characteristic (i) MFR is 0.1 to 2 g / 10 min.
Characteristic (ii) The flexural modulus at 23 ° C. is 850 MPa or more.
Characteristic (iii) The melt tension at 180 ° C. is 120 mN or more.
Characteristic (iv) An equation in which the relationship between the melt tension (MT, unit: mN) measured at 180 ° C., 190 ° C. and 220 ° C. and the measured temperature (t, unit: ° C.) is approximated by the least square method ( The coefficient A (temperature dependence coefficient) of 1) is −0.010 or less.
MT = a × e ^{A × t} formula (1)
In the above formula (1), e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.

  In the ethylene resin composition for sheets of the present invention, the copolymer (I) preferably contains 0.1 to 20% by mass of the radical polymerizable acid anhydride.

  The molded object of this invention is comprised with the said ethylene-type resin composition for sheets, It is characterized by the above-mentioned.

  The ethylene-based resin composition for a sheet of the present invention can provide a high melt tension ethylene-based resin composition for a sheet that is excellent in molding process characteristics and can be recycled, and a molded body thereof.

The ethylene resin composition for a sheet of the present invention comprises a copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers, a polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule, and a reaction. 8 to 38% by mass of an ethylene-based copolymer (A) containing a promoter (III) and having a melt flow rate (MFR) of 1 to 10 g / 10 min measured at a temperature of 190 ° C. and a load of 2.16 kg, Further, it contains 62 to 92% by mass of polyethylene (B) having an MFR of 0.1 to 2 g / 10 min and a density of 0.945 to 0.970 g / cm ³ , and has the following characteristics (i) to (iv): It is characterized by that.
Characteristic (i) MFR is 0.1 to 2 g / 10 min.
Characteristic (ii) The flexural modulus at 23 ° C. is 850 MPa or more.
Characteristic (iii) The melt tension at 180 ° C. is 120 mN or more.
Characteristic (iv) An equation in which the relationship between the melt tension (MT, unit: mN) measured at 180 ° C., 190 ° C. and 220 ° C. and the measured temperature (t, unit: ° C.) is approximated by the least square method ( The coefficient A (temperature dependence coefficient) of 1) is −0.010 or less.
MT = a × e ^{A × t} formula (1)
In the above formula (1), e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.

  Hereinafter, the ethylene-based resin composition for a sheet of the present invention and its use will be described in detail for each item. Further, in the present specification, “to” indicating a numerical range is used in a sense including numerical values described before and after the numerical value as a lower limit value and an upper limit value.

1. 1. Ethylene resin composition for sheet 1-1. Composition ratio of composition The ethylene-based resin composition for a sheet of the present invention contains 8% by mass to 38% by mass of an ethylene copolymer (A) and 62% by mass to 92% by mass of polyethylene (B). Preferably, the ethylene-based copolymer (A) contains 10% by mass to 35% by mass and polyethylene (B) 65% by mass to 90% by mass.
When the ethylene copolymer (A) is 8% by mass or more, in the vacuum forming process, it is possible to suppress the occurrence of inconveniences such as sheet dripping and uneven thickness in the preheating stage of the product, and deep drawing products In this case, it is possible to obtain a desired container shape. When the ethylene copolymer (A) is 38% by mass or less, the required rigidity of the product can be satisfied.
When the polyethylene (B) is 92% by mass or less, it is possible to suppress the occurrence of inconveniences such as sheet sagging and wrinkle in the preheating stage of the product during the vacuum forming process, and the extension of deep drawn products. Defects can be suppressed and a desired container shape can be obtained. When the polyethylene (B) is 62% by mass or more, the required rigidity of the product can be satisfied.

1-2. Characteristics of composition The ethylene resin composition for sheets of the present invention satisfies the following characteristics (i) to (iv).
Characteristic (i) MFR is 0.1 to 2 g / 10 min.
Characteristic (ii) The flexural modulus at 23 ° C. is 850 MPa or more.
Characteristic (iii) The melt tension at 180 ° C. is 120 mN or more.
Characteristic (iv) An equation in which the relationship between the melt tension (MT, unit: mN) measured at 180 ° C., 190 ° C. and 220 ° C. and the measured temperature (t, unit: ° C.) is approximated by the least square method ( The coefficient A (temperature dependence coefficient) of 1) is −0.010 or less.
MT = a × e ^{A × t} formula (1)
In the above formula (1), e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.

Characteristic (i) MFR is 0.1 to 2 g / 10 min.
The ethylene resin composition for sheets of the present invention has a melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg of 0.1 g / 10 min or more and 2 g / 10 min or less, preferably 0.8. It is 2 g / 10 min or more and 1.6 g / 10 min or less.
When the MFR is in this range, the molding stability in each step during production is excellent. When the MFR is 0.1 g / 10 min or more, the extrusion load becomes small and the discharge of the extruder is good. When the MFR is 2 g / 10 min or less, the melt tension is improved and the sheet droops and opens a hole in the thermal forming process. And can be molded into a desired shape.
The MFR was measured under the conditions of 190 ° C. and 2.16 kg load in accordance with “Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic” in JIS K7210. The value of time. The adjustment of MFR can be performed, for example, by adjusting the blending ratio of the ethylene copolymer (A) and the polyethylene (B).

Characteristic (ii) The flexural modulus at 23 ° C. is 850 MPa or more.
The ethylene-based resin composition for a sheet of the present invention has a flexural modulus at 23 ° C. of 850 MPa or more, and preferably 900 MPa or more. Although there is no particular upper limit, it is usually 1800 MPa or less.
When the flexural modulus is 850 MPa or more, the desired rigidity of the product can be obtained, the product can be made self-supporting, and it can be prevented from being greatly deformed when the contents are inserted.
Here, the flexural modulus is a value measured by JIS K7171 by cutting out a 10 mm × 80 × 4 mmt test piece from a 4 mm thick molded sheet prepared by compression molding in accordance with JIS K6922-2.
The flexural modulus can be adjusted by increasing or decreasing the density of the ethylene copolymer (A). Further, for example, the blending ratio of the ethylene copolymer (A) and the polyethylene (B) is adjusted. Can be done.

Characteristic (iii) The melt tension (MT) at 180 ° C. is 120 mN or more.
The ethylene-based resin composition for a sheet of the present invention has a melt tension at 180 ° C. of 120 mN or more, preferably 160 mN or more. When the melt tension is 120 mN or more, dripping of the melted resin at the time of thermal forming can be suppressed.
Here, the melt tension was obtained by extruding a molten resin using a Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd. under a temperature of 180 ° C., an orifice diameter of 2.095 mm, an orifice length of 8.0 mm, and an extrusion speed of 15 mm / min. The unit is mN in the load when wound at a speed of 3.8 m / min.
The melt tension can be adjusted by lowering the MFR or adjusting the blending ratio of the ethylene copolymer (A) and the polyethylene (B).

Characteristic (iv) The temperature dependence coefficient A is -0.010 or less.
The relationship between the melt tension (MT, unit: mN) measured at 180 ° C., 190 ° C., and 220 ° C. and the measurement temperature (t, unit: ° C.) is minimal in the ethylene-based resin composition for sheets of the present invention. The coefficient A (temperature dependence coefficient) of the equation (1) approximated by the square method is −0.010 or less. The lower limit value of the coefficient A is not particularly limited, but is preferably −0.070 or more from the viewpoint of obtaining a desired container shape.
MT = a × e ^{A × t} formula (1)
Here, e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.
When the temperature dependency coefficient A is −0.010 or less, in the vacuum forming process, it is possible to suppress inconveniences such as sheet sagging and uneven thickness in the preheating stage of the product, and deep drawing products In this case, it is possible to obtain a desired container shape.
Equation (1) is an expedient representation of the characteristics of melt tension by an approximate expression using measurement data (measurement temperature and melt tension). That is, an approximate expression of an exponential function can be obtained from the three measurement data by the least square method.
Here, the melt tension can be measured in the same manner as the melt tension measurement method described in the above characteristic (iii) except for the measurement temperature.

2. Ethylene copolymer (A)
The ethylene copolymer (A) which is one of the components constituting the ethylene resin composition for a sheet of the present invention satisfies the following characteristics (a-1) to (a-4).
Characteristic (a-1) It contains a copolymer (I) containing ethylene and a radically polymerizable acid anhydride as constituent monomers.
Characteristic (a-2) Polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule is contained.
Characteristic (a-3) contains a reaction accelerator (III).
Characteristic (a-4) The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 1 to 10 g / 10 min.

Characteristic (a-1) It contains a copolymer (I) containing ethylene and a radically polymerizable acid anhydride as constituent monomers.
The ethylene copolymer (A) contains a copolymer (I) containing ethylene and a radically polymerizable acid anhydride as constituent monomers. The content of the radically polymerizable acid anhydride in the copolymer (I) is preferably in the range of 0.1 to 20% by mass. When the content ratio of the radical polymerizable acid anhydride in the copolymer (I) is 0.1% by mass or more, a desired crosslinking density is obtained, and when it is 20% by mass or less, the ethylene copolymer Desired flexibility, moisture absorption resistance and the like expected for the combined body (A) can be obtained, and the production cost can be further reduced.
The copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers may contain an ethylene polymerizable unsaturated compound other than the radical polymerizable acid anhydride as a constituent monomer, if necessary.

  The content of the monomer derived from the radically polymerizable acid anhydride in the ethylene copolymer (A) is in the range of 0.03 to 10 mol%, more preferably in the range of 0.3 to 5.0 mol%. It is preferable that When the monomer derived from the acid anhydride is 0.03 mol% or more, a desired crosslinking density is obtained, and when it is 10 mol% or less, desired flexibility, moisture absorption resistance, and the like are obtained.

  Examples of the radical polymerizable acid anhydride constituting the ethylene copolymer (A) include maleic anhydride, itaconic anhydride, endic acid anhydride, citraconic anhydride, 1-butene-3,4-dicarboxylic anhydride And alkenyl succinic anhydride having a double bond at the terminal having at most 18 carbon atoms and alkadienyl succinic anhydride having a double bond at the terminal having at most 18 carbon atoms. These may be used alone or in combination of two or more. Of these, maleic anhydride and itaconic anhydride are preferred.

Characteristic (a-2) Polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule is contained.
The ethylene copolymer (A) contains a polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule. In the polyhydric alcohol compound (II), the molar ratio of the hydroxyl group unit in the polyhydric alcohol compound (II) to the unit derived from the radical polymerizable acid anhydride in the ethylene copolymer (A) is 0.00. A range of 01 to 10 is preferable.

The polyhydric alcohol compound (II) refers to a compound having at least two hydroxyl groups in the molecule, and is used for a crosslinking reaction with the copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers.
Examples of the polyhydric alcohol compound (II) include ethylene glycol, glycerin, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, trimethylolmethane, trimethylol. Alcohol compounds such as methylolpropane and pentaerythritol;
Polyethylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol;
Polyglycerols such as diglycerol, triglycerol, tetraglycerol;
Sugars such as arbitol, sorbitol, xylose, arabinose, glucose, galactose, sorbose, fructose, palatinose, maltotriose, marezitose;
Dehydration condensates of these sugars;
A polyoxyalkylene compound obtained by adding ethylene oxide or propylene oxide to the above-mentioned various compounds;
Compounds obtained by partially esterifying the above various compounds with carboxylic acid;
A compound obtained by partially esterifying the above polyoxyalkylene compound with a carboxylic acid;
A polyoxyalkylene compound obtained by adding ethylene oxide or propylene oxide to the partially esterified compound;
Saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol;
Examples thereof include polymers having two or more hydroxyl groups in the molecule, such as polyolefin oligomers having two or more hydroxyl groups and ethylene-hydroxyethyl (meth) acrylate copolymers.
The melting point of the polyhydric alcohol compound is preferably 300 ° C. or lower. These polyhydric alcohol compounds may be used in combination of two or more.

  Examples of the polyhydric alcohol compound (II) include polyoxyalkylene compounds having a structure in which ethylene oxide or propylene oxide is added to the compound represented by the following general formula (I) or general formula (II).

(R ¹ ) _a C (CH ₂ OH) _b General formula (I)
Here, in general formula (I), R ¹ represents hydrogen, a chain or cyclic alkyl group having 1 to 12 carbon atoms, or an aralkyl group, a represents an integer of 0 to 2, and b represents 2 to 4 And is selected to satisfy a + b = 4.

Here, in general formula (II), m is an integer of 0-10.

Characteristic (a-3) contains a reaction accelerator (III).
The ethylene copolymer (A) contains a reaction accelerator (III). The reaction accelerator (III) is contained in the polyhydric alcohol compound (II) with respect to the unit derived from the radical polymerizable acid anhydride in the copolymer (I) containing ethylene and the radical polymerizable acid anhydride as constituent monomers. When the molar ratio of the hydroxyl group units is in the range of 0.01 to 10, the range of 0.001 to 20 parts by mass is preferable with respect to 100 parts by mass of the copolymer (I). The reaction accelerator (III) activates a carbonyl group contained in a unit derived from the radical polymerizable acid anhydride contained in the copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers, It is a compound that promotes the reaction of the polyhydric alcohol compound (II) with the hydroxyl group.
There are various types of such reaction accelerators (III). For example, there are metal salts of organic carboxylic acids. Examples of metal salts of organic carboxylic acids include those of fatty acids having 1 to 30 carbon atoms, such as acetic acid, propionic acid, butyric acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, olein Examples include salts of acids, behenic acid, and the like with metals of Group 1, Group 2, Group 12, Group 13 (for example, Li, Na, K, Mg, Ca, Zn, Al, etc.) of the periodic table. . Specific examples include lithium acetate, sodium acetate, magnesium acetate, aluminum acetate, potassium butyrate, calcium butyrate, zinc butyrate, sodium octoate, calcium octoate, potassium decanoate, magnesium decanoate, zinc decanoate, lauric acid Lithium, sodium laurate, calcium laurate, aluminum laurate, potassium myristate, sodium myristate, aluminum myristate, sodium palmitate, zinc palmitate, magnesium palmitate, sodium stearate, potassium stearate, calcium stearate, stearic acid Examples include zinc, sodium oleate, and sodium behenate. Of these, lithium laurate, sodium laurate, calcium laurate, aluminum laurate, potassium myristate, sodium myristate, aluminum myristate, sodium palmitate, zinc palmitate, magnesium palmitate, sodium stearate, potassium stearate , Calcium stearate, zinc stearate, sodium oleate and the like are suitable.

  Another example of a metal salt of an organic carboxylic acid is a polymer having a metal salt structure of a carboxylic acid. Examples of such polymers include metals of Group 1, Group 2, Group 12, and Group 13 of ethylene and radical polymerizable unsaturated carboxylic acid (for example, Li, Na, K, Mg, Ca, Zn, Al Etc.) having a structure in which a salt is copolymerized, or having a structure in which a metal salt of ethylene and a radically polymerizable carboxylic acid and other radically polymerizable unsaturated carboxylic acid and / or a derivative thereof are copolymerized Can be mentioned.

  Further, a radically polymerizable unsaturated carboxylic acid metal salt (may be polymerized with a free unsaturated carboxylic acid and then neutralized) to a polyolefin polymer such as polyethylene, polypropylene, and free ethylene-propylene copolymer. And those having a structure in which a metal salt of a radical polymerizable carboxylic acid and another radical polymerizable unsaturated carboxylic acid and / or a derivative thereof are simultaneously co-grafted to a polyolefin polymer. It is done. The radical polymerizable unsaturated carboxylic acid and derivatives thereof used here include (meth) acrylic acid, maleic acid, fumaric acid, monomethyl maleate, monomethyl fumarate, monoethyl maleate, monoethyl fumarate, monobutyl maleate, fumarate Examples thereof include monobutyl acid, methyl (meth) acrylate, dimethyl maleate, dimethyl fumarate, diethyl maleate, diethyl fumarate, dibutyl maleate, and dibutyl fumarate.

  Other examples of reaction accelerators include tertiary amine compounds. Specific examples of the tertiary amine compound used here include trimethylamine, triethylamine, triisopropylamine, trihexylamine, trioctylamine, trioctadecylamine, dimethylethylamine, methyldioctylamine, dimethyloctylamine, diethylcyclohexylamine, N N-diethyl-4-methylcyclohexylamine, diethylcyclododecylamine, N, N-diethyl-1-adamantanamine, 1-methylpyrrolidine, 1-ethylpyrrolidine, 1-ethylpiperidine, quinuclidine, triphenylamine, N N-dimethylaniline, N, N-diethylaniline, N, N-dimethyl-m-phenethiazine, 4-t-butyl-N, N-dimethylaniline and the like.

  Other examples of reaction accelerators can further include quaternary ammonium salts. Examples of the quaternary ammonium salt used herein include tetramethylammonium tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetramethylammonium promide, tetraethylammonium promide, methyltri-n-butylammonium chloride, and tetrabutylammonium prochloride. Amide, tetrahexylammonium promide, tetraheptylammonium promide, phenyltrimethylammonium promide, benzyltriethylammonium chloride and the like.

  Furthermore, a metal hydroxide of Group 2, 12 or 13 or a metal halide of Group 2 or 12 can be used as a reaction accelerator. Here, examples of the metal hydroxides of Group 2, Group 12, and Group 13 include calcium hydroxide, magnesium hydroxide, and aluminum hydroxide, and Group 2 and Group 12 metals. Examples of the halide include calcium chloride, calcium bromide, and magnesium chloride.

In addition, LiBF ₄ , NaBF ₄ , KBF ₄ , NaPF ₆ , KPF ₆ , NaPCl ₆ , KPCl ₆ , NaFeCl ₄ , NaSnCl ₄ , NaSbF ₆ , NaAsF ₆ , NaAsCl ₆ , alkali metal such as KAsCl _6, etc. Can be used as an accelerator.

  Of the reaction accelerators exemplified above, a metal salt of a polymer containing a carboxyl group and a metal salt of an organic carboxylic acid are preferably used. In addition, two or more kinds of the above various reaction accelerators can be used in combination as necessary.

Characteristic (a-4) The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 1 to 10 g / 10 min.
The MFR of the ethylene copolymer (A) is 1 to 10 g / 10 minutes, preferably 3 to 8 g / 10 minutes.
When the MFR is 1 g / 10 min or more, the moldability of the ethylene-based resin composition for sheets, particularly the melt fluidity, is stable, and when the MFR is 10 g / 10 min or less, the impact strength of the molded article becomes good.
In the present specification, the MFR of the ethylene-based polymer is 190 ° C. in accordance with JIS K7210 “Testing method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic”. The value when measured under the condition of 2.16 kg load. The MFR can be adjusted by changing the polymerization temperature of the ethylene polymer, and can be increased by increasing the polymerization temperature.

3. Polyethylene (B)
Polyethylene (B), which is one of the components constituting the ethylene-based resin composition for sheets of the present invention, is a homopolymer of ethylene and / or a copolymer of ethylene and α-olefin, and has the following characteristics ( b-1) and (b-2) are satisfied.
Characteristic (b-1) The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 2 g / 10 minutes.
Characteristics (b-2) density of 0.945 g / cm ³ or more 0.970 g / cm ³ or less.

As a kind of polyethylene-type resin of the polyethylene (B) of this invention, it is preferable that it is an ethylene-type polymer, and it is preferable that it is a homopolymer of ethylene and / or a copolymer of ethylene and an alpha olefin.
Polyethylene (B) is a homopolymer of ethylene or ethylene and an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene. It can be obtained by copolymerization with the like. Further, depending on the purpose, copolymerization with a diene is also possible. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene, and the like. The comonomer content in the polymerization of polyethylene (B) can be arbitrarily selected. For example, in the case of copolymerization of ethylene and an α-olefin having 3 to 12 carbon atoms, ethylene · α -The alpha olefin content in an olefin copolymer is 0-40 mol%, Preferably it is 0-30 mol%.

Characteristic (b-1) The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 2 g / 10 minutes.
The MFR of polyethylene (B) is 0.1 g / 10 min or more and 2 g / 10 min or less, preferably 0.2 g / 10 min or more and 1 g / 10 min or less.
When the MFR is 0.1 g / 10 min or more, the molding processability of the ethylene-based resin composition for sheets, particularly the melt fluidity, is stable, and when the MFR is 2 g / 10 min or less, the melt tension of the molded body is improved.
In this specification, the MFR of polyethylene is 190 ° C. according to JIS K7210 “Testing Method for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Plastic-Thermoplastic Plastic”. The value when measured under a 16 kg load condition. The MFR can be adjusted by changing the amount of chain transfer agent (hydrogen, etc.) coexisting during ethylene polymerization or by changing the polymerization temperature, increasing the amount of hydrogen or increasing the polymerization temperature. By doing so, it can be enlarged.

Characteristics (b-2) density of 0.945 g / cm ³ or more 0.970 g / cm ³ or less.
Density polyethylene (B) is, 0.945 g / cm ³ or more 0.970 g / cm ³ or less, preferably 0.950 g / cm ³ or more 0.965 g / cm ³ or less.
When the density is in this range, the molded article has excellent rigidity. When the density is 0.945 g / cm ³ or more, the desired rigidity of the product can be obtained, and the desired shape can be maintained when the contents are put. Further, when the density is 0.970 g / cm ³ or less, the production becomes easy.
In addition, in this specification, the density of polyethylene says the value when measured with the following method. The density can be adjusted, for example, by changing the amount of α-olefin copolymerized with ethylene, and can be reduced by increasing the amount of α-olefin.

  The density can be measured by the following method. That is, a 2 mm thick press sheet is prepared by hot pressing polyethylene pellets, the sheet is placed in a beaker having a capacity of 1000 ml, filled with distilled water, covered with a watch glass, and heated with a mantle heater. After boiling boiling water for 60 minutes, place the beaker on a wooden table and let it cool. At this time, the boiling distilled water after boiling for 60 minutes is adjusted to 500 ml so that the time until it reaches room temperature is not less than 60 minutes. Further, the test sheet is immersed in a substantially central portion in water so as not to contact the beaker and the water surface. After annealing the sheet at a temperature of 23 ° C. and a humidity of 50% within a period of 16 hours to 24 hours, the sheet was punched out to 2 mm in length and width, and the test temperature was 23 ° C. And the specific gravity measurement method ”.

4). Mixing of ethylene copolymer (A) and polyethylene (B) The ethylene resin composition for a sheet of the present invention is obtained by mixing an ethylene copolymer (A) and polyethylene (B), and is manufactured separately. It can manufacture by mixing the ethylene-type copolymer (A) and polyethylene (B) which were made by the well-known method.

The ethylene-based resin composition for sheets of the present invention can be pelletized by mechanical melt mixing using a pelletizer, homogenizer, or the like according to a conventional method, and then molded by various molding machines to obtain a desired molded product.
In addition, according to a conventional method, an ethylene resin composition for a sheet obtained by the above method includes, in addition to other olefin polymers and rubbers, an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, and an antistatic agent. Known additives such as an agent, an antifogging agent, an antiblocking agent, a processing aid, a color pigment, a crosslinking agent, a foaming agent, an inorganic or organic filler, and a flame retardant can be blended.
As additives, for example, one or more antioxidants (phenolic, phosphorus, sulfur), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like can be used in combination as appropriate. As filler, calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silica, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used. Of these, calcium carbonate, talc and mica are preferably used. In any case, various additives can be blended into the ethylene resin composition as necessary, and the mixture can be kneaded with a kneading extruder, Banbury mixer, or the like to obtain a molding material.

5. Molding and Use of Sheet-Based Ethylene Resin Composition For the sheet-based ethylene resin composition, a conventionally known molding method can be used.
Although it does not specifically limit as a molded article, It is suitable for manufacturing a large sized or deep drawing product.

  In the following, the present invention will be described in more detail with reference to examples and comparative examples, and the superiority of the present invention and the superiority in the configuration of the present invention will be demonstrated, but the present invention is limited by these examples. It is not a thing.

[Methods for measuring physical properties and methods for evaluating compositions]
(1) MFR
According to JIS K7210 “Testing Method for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MFR) of Plastic-Thermoplastic Plastic”, the measurement was performed under the conditions of 190 ° C. and 2.16 kg load.
(2) Density Polyethylene pellets were hot-pressed to prepare a 2 mm-thick press sheet. The sheet was placed in a beaker having a capacity of 1000 ml, filled with distilled water, covered with a watch glass, and heated with a mantle heater. After boiling boiling water for 60 minutes, place the beaker on a wooden table and let it cool. At this time, the boiling distilled water after boiling for 60 minutes was adjusted to 500 ml so that the time until reaching room temperature was not less than 60 minutes. Moreover, the test sheet was immersed in the substantially center part in water so that it might not contact a beaker and the water surface. After annealing the sheet at a temperature of 23 ° C. and a humidity of 50% for 16 hours to 24 hours, the sheet is punched out to 2 mm in length and width, and tested at 23 ° C., JIS K7112 “Plastic-non-foamed plastic density And measurement method of specific gravity ”.
(3) Flexural modulus A 10 mm × 80 × 4 mmt test piece was cut out from a 4 mm thick molded sheet prepared by compression molding in accordance with JIS K6922-2, and measured according to JIS K7171 at an ambient temperature of 23 ° C.
(4) Melt tension Using a Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd., the molten resin was extruded under the conditions of a temperature of 180 ° C., an orifice diameter of 2.095 mm, an orifice length of 8.0 mm, and an extrusion speed of 15 mm / min. The load (unit: mN) when wound at a speed of 3.8 m / min was measured.
(5) Temperature dependence coefficient A
In the measurement of the melt tension, the melt tension was measured at three points of measurement temperatures of 180 ° C., 190 ° C., and 220 ° C. The relationship between melt tension (y-axis) and measurement temperature (x-axis) was determined by the following approximate expression calculated by the method of least squares.
Melt tension (MT) = a × e ^{A × measured temperature (t)} Formula (1)
Here, e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.

(6) Extrudability A sample satisfying MFR at 190 ° C. of 0.1 to 2 g / 10 min was designated as “◯”, and the others were designated as “x”. When the extrudability is “○”, there was almost no sudden increase in resin pressure or motor torque when forming the raw sheet. However, when the extrudability is “x”, a severe resin was formed in the original sheet. The pressure and motor torque increased, and extrusion with the T-die could not be performed normally.
(7) Secondary workability In the vacuum forming process, “○” indicates that the molding of large products and deep drawing products such as cups are stable. In the case of large products in the vacuum forming process, the preheating stage. In this case, “x” indicates that the sheet hangs and causes inconvenience such as uneven thickness or wrinkles.
(8) Product rigidity The thing whose bending elastic modulus in 23 degreeC is 850 Mpa or more was set to "(circle)", and other than that was set to "x". When the product rigidity is “◯”, it can be used without problems when a container, a tray, or an automobile interior part is manufactured. However, when the product rigidity is “X”, it is difficult to satisfy the required rigidity of the product.
(9) Comprehensive evaluation “○” indicates that the above extrudability, secondary workability, and product rigidity are satisfied at the same time, and “x” indicates the others.

[Example 1]
(1) Production of ethylene copolymer (A) Using a high-pressure polyethylene production facility having a tank reactor, MFR 12 g / 10 min, ethylene having a unit derived from maleic anhydride of 2.5% by mass and Copolymer (I) with maleic anhydride was prepared.
With respect to 94% by mass of this copolymer (I), 1% by mass of trimethylolpropane (hydroxyl group / acid anhydride group = 0.93), MFR 5 g / 10 min as a metal salt of organic carboxylic acid, density 0.940 g / A partially neutralized ethylene-methacrylic acid copolymer of cm ³ (a methacrylic acid content of 18% by mass, a copolymer obtained by neutralizing about 10 mol% of the methacrylic acid with sodium ions. 5% by mass (abbreviated as a)) (metal atom / acid anhydride group = 3.75) was mixed.
In mixing, the three components were dry blended with a tumbler, and then melt-kneaded at 250 ° C. and pelletized using a 30 mmφ twin screw extruder. The mixture was an ethylene copolymer (A), and its MFR was 4 g / 10 min.

(2) Production of polyethylene (B) (catalyst preparation)
15 g of a catalyst (made by WR Grace) having a chromium atom loading amount of 1.1% by mass, a specific surface area of 500 m ² / g, and a pore volume of 1.5 cm ³ / g is provided with a perforated plate, It was put in a quartz glass tube having a diameter of 5 cm, set in a cylindrical firing electric furnace, fluidized with air passed through molecular sieves, and fired at 500 ° C. for 18 hours at a linear velocity of 6 cm / s. An orange chrome catalyst was obtained indicating that it contained hexavalent chromium atoms.
(polymerization)
A 2.0 L autoclave sufficiently purged with nitrogen was charged with 100 mg of the calcined activated chromium catalyst obtained in the preparation of the catalyst and 0.8 L of isobutane, and the internal temperature was raised to 108 ° C. While maintaining the ethylene partial pressure to be 1.4 MPa, the polymerization was carried out so that the catalyst productivity was 3000 g-polymer / g-catalyst. The obtained polyethylene had an MFR of 0.8 g / 10 min and a density of 0.960 g / cm ³ .

(3) Evaluation of ethylene-based resin composition for sheet The ethylene-based copolymer (A) and polyethylene (B) were melt-mixed at the composition ratio shown in Table 1 to produce an ethylene-based resin composition for sheet. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition is excellent in molding processability, and can produce a large-sized or deep-drawn molded article. Moreover, since the recycled material MFR also did not change, recycling was possible.

[Example 2] to [Example 4]
The same procedure as in Example 1 was carried out except that the ethylene copolymer (A) and polyethylene (B) were melt mixed at the composition ratio shown in Table 1. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition is excellent in molding processability, and can produce a large-sized or deep-drawn molded article. Moreover, since the recycled material MFR also did not change, recycling was possible.

[Example 5]
(1) Production of polyethylene (B) (Preparation of chromium catalyst)
15 g of a catalyst (made by WR Grace) having a chromium atom loading amount of 1.1% by mass, a specific surface area of 500 m ² / g, and a pore volume of 1.5 cm ³ / g is provided with a perforated plate, It was put in a quartz glass tube having a diameter of 5 cm, set in a cylindrical firing electric furnace, fluidized with air passed through molecular sieves, and fired at 730 ° C. for 18 hours at a linear velocity of 6 cm / s. An orange chrome catalyst was obtained indicating that it contained hexavalent chromium atoms.
(polymerization)
Into a 2.0 L autoclave sufficiently purged with nitrogen, 100 mg of the above-mentioned calcination-activated chromium catalyst and 0.8 L of isobutane were charged, and the internal temperature was raised to 108 ° C. While maintaining the ethylene partial pressure at 1.0 MPa, the polymerization was carried out so that the catalyst productivity was 2500 g-polymer / g-catalyst. Subsequently, the polymerization was terminated by releasing the content gas out of the system.
The obtained polyethylene had an MFR of 0.2 g / 10 min and a density of 0.956 g / cm ³ .
(2) Evaluation of ethylene resin composition for sheet The same procedure as in Example 1 was conducted except that polyethylene (B) shown in Table 1 was used and the blending ratio shown in Table 1 was used. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition is excellent in molding processability, and can produce a large-sized or deep-drawn molded article. Moreover, since the recycled material MFR also did not change, recycling was possible.

[Example 6]
(1) Production of ethylene copolymer (A) Using a high-pressure polyethylene production facility having a tank reactor, ethylene and maleic anhydride having an MFR of 30 g / 10 min and a unit derived from maleic anhydride of 3% by mass To produce a copolymer (I).
Partial neutralization of ethylene-methacrylic acid copolymer having a trimethylolpropane content of 1% by mass, an organic carboxylic acid metal salt of MFR 12 g / 10 min, and a density of 0.949 g / cm ³ with respect to 94% by mass of this copolymer. 5% by mass of a product (a methacrylic acid content of 18% by mass, a copolymer obtained by neutralizing about 10 mol% of the methacrylic acid with sodium ions, hereinafter abbreviated as a metal salt (a)) was mixed.
In mixing, the three components were dry blended with a tumbler, and then melt-kneaded at 250 ° C. and pelletized using a 30 mmφ twin screw extruder. The mixture was an ethylene copolymer (A), and its MFR was 8.0 g / 10 min.
(2) Evaluation of ethylene resin composition for sheet The same procedure as in Example 2 was conducted except that the ethylene copolymer (A) shown in Table 1 was used. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition is excellent in molding processability, and can produce a large-sized or deep-drawn molded article. Moreover, since the recycled material MFR also did not change, recycling was possible.

[Example 7] to [Example 8]
(1) Production of polyethylene (B) (catalyst preparation)
115 g of magnesium ethoxide, 151 g of tri-n-butoxymonochloro titanium and 37 g of n-butanol were mixed at 150 ° C. for 6 hours to make uniform. Next, the temperature was lowered to 60 ° C., and n-hexane was added to obtain a uniform solution. Next, 457 g of ethylaluminum sesquichloride was dropped at a predetermined temperature and stirred for 1 hour. 210g of catalyst components were obtained by wash | cleaning the produced | generated precipitation with n-hexane. The obtained solid was dried to obtain a powder. This powder contained 11.0% by mass of Mg and 10.5% by mass of Ti.
(polymerization)
Supply the solid catalyst component 1.5g / hr obtained in the above (preparation of catalyst) from the catalyst supply line and triethylaluminum to the first-stage polymerization reactor with an internal volume of 200 liters as the first-stage reactor. A polymerization solvent (n-hexane) 70 (l / hr), hydrogen 78 (mg / hr), ethylene 13.8 at 70 ° C. while supplying 40 mmol / hr from the line and discharging the polymerization contents at a required rate. (Kg / hr), 1-butene was fed at a rate of 0.10 (kg / hr), and the first-stage copolymerization was continuously performed under the conditions of a total pressure of 1.3 MPa and an average residence time of 2.4 hr. .
The slurry polymerization product produced in the first stage reactor was introduced into the second stage reactor having an internal volume of 400 liters as it was through a continuous tube having an inner diameter of 50 mm, and the contents of the polymerizer were discharged at the required speed. Polymerization solvent (n-hexane) 100 (l / hr), hydrogen 31.9 (g / hr), ethylene 43.8 (kg / hr) were fed at 82 ° C., total pressure 1.1 MPa, average The second-stage polymerization was continuously performed under the condition of a residence time of 1.8 hours.
The polymerization product discharged from the second stage reactor was introduced into a flushing tank, the polymerization product was continuously withdrawn, and unreacted gas was removed from the degassing line.
The obtained polyethylene had an MFR of 1.0 g / 10 min and a density of 0.964 g / cm ³ .
(2) Evaluation of ethylene resin composition for sheet The same procedure as in Example 1 was conducted except that polyethylene (B) shown in Table 1 was used and the blending ratio shown in Table 1 was used. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition is excellent in molding processability, and can produce a large-sized or deep-drawn molded article. Moreover, since the recycled material MFR also did not change, recycling was possible.

[Comparative Example 1]
Using only the polyethylene (B) of Example 1, the physical properties were evaluated. The physical properties and evaluation results are shown in Table 1. The obtained composition was inferior in secondary workability because of low temperature dependence of melt tension and poor rise of melt tension in a low temperature range.

[Comparative Example 2]
Using only the polyethylene (B) of Example 5, the physical properties were evaluated. The physical properties and evaluation results are shown in Table 1. The obtained composition was inferior in secondary workability because of low temperature dependence of melt tension and poor rise of melt tension in a low temperature range.

[Comparative Example 3]
Physical properties were evaluated using only the polyethylene (B) of Example 7. The physical properties and evaluation results are shown in Table 1. The obtained composition was inferior in secondary workability because of low temperature dependence of melt tension and poor rise of melt tension in a low temperature range.

[Comparative Example 4]
The ethylene copolymer (A) and polyethylene (B) of Example 1 were used and melt mixed at the composition ratio shown in Table 1 to produce an ethylene resin composition for a sheet. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition was inferior in secondary workability because of low temperature dependence of melt tension and poor rise of melt tension in a low temperature range.

[Comparative Example 5]
The ethylene-based copolymer (A) of Example 6 and the polyethylene (B) of Example 5 were used and melt-mixed at the composition ratios shown in Table 1 to produce an ethylene-based resin composition for sheets. The physical properties and evaluation results of the resin composition are shown in Table 1. The obtained composition was inferior in secondary workability because of low temperature dependence of melt tension and poor rise of melt tension in a low temperature range.

[Comparative Example 6]
Novatec ^™ HD HB216R was used as the polyethylene component (B), and the physical properties and evaluation results of the resin are shown in Table 1. HB216R had a large extrusion load and could not be molded.

  The ethylene-based resin composition for a sheet of the present invention can provide a high melt tension ethylene-based resin composition for a sheet that is excellent in molding characteristics and can be recycled, and a molded body thereof. Useful.

Claims (3)

A copolymer (I) containing ethylene and a radical polymerizable acid anhydride as constituent monomers, a polyhydric alcohol compound (II) having at least two hydroxyl groups in the molecule, and a reaction accelerator (III), and having a temperature of 190 ° C. , An ethylene copolymer (A) having a melt flow rate (MFR) of 1 to 10 g / 10 minutes measured at a load of 2.16 kg, 8 to 38% by mass, and an MFR of 0.1 to 2 g / 10 minutes, An ethylene-based resin composition for a sheet containing 62 to 92% by mass of polyethylene (B) having a density of 0.945 to 0.970 g / cm ³ and having the following characteristics (i) to (iv).
Characteristic (i) MFR is 0.1 to 2 g / 10 min.
Characteristic (ii) The flexural modulus at 23 ° C. is 850 MPa or more.
Characteristic (iii) The melt tension at 180 ° C. is 120 mN or more.
Characteristic (iv) An equation in which the relationship between the melt tension (MT, unit: mN) measured at 180 ° C., 190 ° C. and 220 ° C. and the measured temperature (t, unit: ° C.) is approximated by the least square method ( The coefficient A (temperature dependence coefficient) of 1) is −0.010 or less.
MT = a × e ^{A × t} formula (1)
In the above formula (1), e is the base of the natural logarithm (Napier number), and a is a coefficient determined by approximation.   The ethylene-based resin composition for sheets according to claim 1, wherein the copolymer (I) contains 0.1 to 20% by mass of the radical polymerizable acid anhydride.   The molded object comprised with the ethylene-type resin composition for sheets of Claim 1 or 2.