KR102766413B1 - Non-foaming sheets and containers - Google Patents

Abstract

The present invention has as its object the provision of a polypropylene sheet having excellent rigidity and heat resistance. The present invention is a non-foamed sheet having a layer formed from a propylene polymer composition, wherein the composition contains a specific propylene polymer (A) and a propylene polymer (B) having a melting point of 120 to 170°C and an intrinsic viscosity [η] measured at 135°C in a tetralin solvent of more than 1.5 dl/g and 5.0 dl/g or less, and wherein the content of the propylene polymer (A) is 2 to 30 parts by mass and the content of the propylene polymer (B) is 70 to 98 parts by mass relative to 100 parts by mass of the total of the propylene polymer (A) and the propylene polymer (B).

Description

Non-foaming sheets and containers

The present invention relates to a non-foaming sheet and a container.

Propylene polymers are widely used as materials for various types of molded articles (see, for example, Patent Documents 1 to 2), and the required properties also vary depending on the molding method or application. For example, propylene polymers are materials with excellent impact resistance, hygiene, and environmental compatibility, and are used as sheets or sheet-molded containers (see, for example, Patent Documents 3 to 4).

International Publication No. 1999/007752 International Publication No. 2005/097842 Japanese Patent Publication No. 2010-159320 Japanese Patent Publication No. 2015-010105

Due to environmental issues, thinning of the sheet is required, and therefore, improvement of rigidity is required. In addition, depending on the use of the sheet, for example, there are cases where it is heated by a microwave oven or the like, and therefore high heat resistance is required. The present invention aims to provide a polypropylene sheet having excellent rigidity and heat resistance, and a container obtained from the sheet.

The inventors of the present invention, after repeated examination, have discovered that the polypropylene sheet described below can solve the above problems, and have completed the present invention.

[1] A non-foamed sheet having a layer formed from a propylene polymer composition, wherein the propylene polymer composition comprises a propylene polymer (A) having 20 to 50 mass% of a propylene polymer (a1) having an intrinsic viscosity [η] of 10 to 12 dl/g as measured in a tetralin solvent at 135°C, and 50 to 80 mass% of a propylene polymer (a2) having an intrinsic viscosity [η] of 0.5 to 1.5 dl/g as measured in a tetralin solvent at 135°C (provided that the total amount of the propylene polymer (a1) and the propylene polymer (a2) is 100 mass%), and a propylene polymer (B) having a melting point of 120 to 170°C and an intrinsic viscosity [η] of more than 1.5 dl/g and 5.0 dl/g as measured in a tetralin solvent at 135°C. A non-foaming sheet characterized in that the content of the propylene polymer (A) is 2 to 30 parts by mass and the content of the propylene polymer (B) is 70 to 98 parts by mass, based on 100 parts by mass of the total of the propylene polymer (A) and the propylene polymer (B).

[2] A non-foaming sheet according to [1], wherein the molecular weight distribution (Mw/Mn) of the propylene polymer composition measured by gel permeation chromatography (GPC) is 6.0 or more.

[3] A non-foamed sheet according to [1] or [2], wherein the melt flow rate (MFR) of the propylene polymer (B) measured at 230°C and a load of 2.16 kg is 0.1 to 10 g/10 minutes.

[4] A non-foamed sheet according to any one of [1] to [3], wherein the molecular weight distribution (Mw/Mn) of the propylene polymer (B) exceeds 5 as measured by gel permeation chromatography (GPC).

[5] A non-foaming sheet according to any one of [1] to [4] above having a thickness of 200 μm or more.

[6] A non-foaming sheet according to any one of [1] to [5], which is a single-layer sheet formed of a layer formed from the propylene-based polymer composition.

[7] A non-foaming sheet according to any one of [1] to [5], which is a laminated sheet having a layer formed from the propylene-based polymer composition.

[8] A container formed from a non-foaming sheet as described in any one of [1] to [7] above.

According to the present invention, a polypropylene sheet having excellent rigidity and heat resistance and a container obtained from the sheet can be provided.

The non-foaming sheet of the present invention has a layer formed of a propylene polymer composition containing a propylene polymer (A) and a propylene polymer (B), each of which is described below.

Meanwhile, details of the measurement conditions for each requirement are described in the examples.

[Propylene polymer (A)]

The propylene polymer (A) contains 20 to 50 mass% of a propylene polymer (a1) having an intrinsic viscosity [η] of 10 to 12 dl/g as measured in a tetralin solvent at 135°C, and 50 to 80 mass% of a propylene polymer (a2) having an intrinsic viscosity [η] of 0.5 to 1.5 dl/g as measured in a tetralin solvent at 135°C [however, the total amount of the propylene polymer (a1) and the propylene polymer (a2) is 100 mass%.]

Hereinafter, the ultimate viscosity [η] measured at 135°C in a tetralin solvent is also simply referred to as “the ultimate viscosity [η].” The mass fractions of each of the propylene polymer (a1) and the propylene polymer (a2) are based on the total amount of (a1) and (a2).

<Propylene polymer (a1)>

The ultimate viscosity [η] of the propylene polymer (a1) is in the range of 10 to 12 dl/g, and preferably in the range of 10.5 to 11.5 dl/g. In addition, the mass fraction of the propylene polymer (a1) in the propylene polymer (A) is in the range of 20 to 50 mass%, and preferably 20 to 45 mass%, more preferably 20 to 40 mass%, and even more preferably 22 to 40 mass%.

As the propylene polymer (a1), for example, a homopolymer of propylene, a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (except propylene) can be mentioned, and a homopolymer of propylene is preferable. As the α-olefin having 2 to 8 carbon atoms, for example, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene can be mentioned. Of these α-olefins, ethylene is preferable. One or more α-olefins can be used.

When the ultimate viscosity [η] of the propylene polymer (a1) exceeds 12 dl/g, the sheet formability tends to be poor. In addition, when the ultimate viscosity [η] of the propylene polymer (a1) is less than 10 dl/g, the rigidity tends not to be sufficiently improved.

When the mass fraction of the propylene polymer (a1) is less than 20 mass%, the rigidity and heat resistance of the obtained sheet tend to be insufficient, and when it exceeds 50 mass%, it tends to cause poor appearance during sheet molding.

Propylene polymers (a1) can be used in one or more types.

<Propylene polymer (a2)>

The ultimate viscosity [η] of the propylene polymer (a2) is in the range of 0.5 to 1.5 dl/g, preferably 0.6 to 1.5 dl/g, more preferably 0.8 to 1.5 dl/g. Furthermore, the mass fraction of the propylene polymer (a2) in the propylene polymer (A) is in the range of 50 to 80 mass%, preferably 55 to 80 mass%, more preferably 60 to 80 mass%, and even more preferably 60 to 78 mass%.

As the propylene polymer (a2), for example, a homopolymer of propylene, a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (except propylene) can be mentioned, and a homopolymer of propylene is preferable. As the α-olefin having 2 to 8 carbon atoms, for example, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene can be mentioned. Of these α-olefins, ethylene is preferable. One or more α-olefins can be used.

When the ultimate viscosity [η] of the propylene polymer (a2) is less than 0.5 dl/g, the rigidity of the obtained polymer composition tends to be insufficiently improved, and when the ultimate viscosity [η] exceeds 1.5 dl/g, the viscosity is high and the sheet formability tends to deteriorate.

If the mass fraction of the propylene polymer (a2) is less than 50 mass%, it causes poor appearance during sheet molding, and if it exceeds 80 mass%, there is a tendency for the rigidity improvement to be insufficient.

Propylene polymers (a2) can be used in one or more types.

<Additives>

In the propylene polymer (A), additives such as antioxidants, neutralizers, flame retardants, and crystal nucleating agents can be blended as needed. One or more types of additives can be used. The ratio of the additives is not particularly limited and can be appropriately adjusted.

<Properties of propylene polymer (A)>

The propylene polymer (A) has a melt flow rate (MFR) measured at 230°C and a load of 2.16 kg, preferably in a range of 0.01 to 5 g/10 min, more preferably in a range of 0.05 to 4 g/10 min, and even more preferably in a range of 0.1 to 3 g/10 min. When the MFR of the propylene polymer (A) is in the above range, the sheet formability is excellent.

<Method for producing propylene polymer (A)>

As a method for producing a propylene polymer (A), various known production methods can be mentioned, and for example, a method (1) in which a propylene polymer (a1) and a propylene polymer (a2) satisfying the above properties are respectively produced, and then the propylene polymer (a1) and the propylene polymer (a2) are mixed or melt-blended within the above range to obtain a propylene polymer (A); a method (2) in which a propylene polymer (a1) and a propylene polymer (a2) satisfying the above properties are produced in one polymerization system or two or more polymerization systems to obtain a propylene polymer (A).

In method (1), for example, a propylene polymer (a1), a propylene polymer (a2), and additives, etc., as needed, are mixed using a Henschel mixer, a V-type blender, a tumbler blender, a ribbon blender, etc., and then melt-mixed using a single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc., thereby obtaining a high-quality propylene polymer (A) in which each of the above components is uniformly dispersed and mixed. The resin temperature at the time of melt-mixing is usually 180 to 280°C, and preferably 200 to 260°C.

In method (2), a propylene polymer (A) including a relatively high molecular weight propylene polymer (a1) and a relatively low molecular weight propylene polymer (a2) can be obtained by multi-stage polymerization of two or more stages. An additive may be added to the obtained propylene polymer (A) as needed.

As a preferable method for producing a propylene polymer (A), the above method (2) can be mentioned, and for example, a method in which propylene alone or in combination with another monomer is polymerized in two or more stages in the presence of a catalyst for producing highly stereoregular polypropylene can be mentioned.

Specifically, in the first-stage polymerization, propylene or propylene and an α-olefin having 2 to 8 carbon atoms are polymerized substantially in the absence of hydrogen to produce a relatively high molecular weight propylene polymer (a1) having an intrinsic viscosity [η] of 10 to 12 dl/g, preferably 10.5 to 11.5 dl/g, in an amount of 20 to 50 mass%, preferably 20 to 45 mass%, more preferably 20 to 40 mass%, of the propylene polymer (A), and in the second-stage and subsequent polymerizations, a relatively low molecular weight propylene polymer (a2) is produced.

The intrinsic viscosity [η] of the relatively low molecular weight propylene polymer (a2) produced in the polymerization from the second stage onwards is 0.5 to 1.5 dl/g, preferably 0.6 to 1.5 dl/g, more preferably 0.8 to 1.5 dl/g. In addition, this intrinsic viscosity [η] is the intrinsic viscosity [η] of the propylene polymer produced solely in that stage, and is not the intrinsic viscosity [η] of the entire propylene polymer including up to the shear of that stage.

In addition, in the polymerization from the second stage onwards, the MFR of the finally obtained propylene polymer (A) is preferably adjusted to 0.01 to 5 g/10 min, more preferably 0.05 to 4 g/10 min, and even more preferably 0.1 to 3 g/10 min.

The method for adjusting the ultimate viscosity [η] of the propylene polymer manufactured in the second stage and thereafter is not particularly limited, but a method using hydrogen as a molecular weight regulator is preferable.

As for the manufacturing order (polymerization order) of the propylene polymer (a1) and the propylene polymer (a2), it is preferable to manufacture a relatively high molecular weight propylene polymer (a1) in the first stage substantially in the absence of hydrogen, and then manufacture a relatively low molecular weight propylene polymer (a2) in the presence of, for example, hydrogen in the second stage and thereafter. The manufacturing order can be reversed, but in order to manufacture a relatively low molecular weight propylene polymer (a2) in the first stage and then manufacture a relatively high molecular weight propylene polymer (a1) in the second stage and thereafter, it is necessary to remove the molecular weight regulator such as hydrogen contained in the reaction product of the first stage without limit before the start of polymerization in the second stage and thereafter, so the polymerization device becomes complicated, and furthermore, it is difficult for the intrinsic viscosity [η] in the second stage and thereafter to increase.

The polymerization of each stage in the multistage polymerization may be performed continuously or in a batch manner, but it is preferable to perform it in a batch manner. The propylene polymer (A) containing the propylene polymer (a1) and the propylene polymer (a2) obtained by the multistage polymerization using a batch manner has the propylene polymer (a1) which is an ultra-high molecular weight component well dispersed, and therefore a sheet having excellent rigidity and heat resistance is obtained. In addition, when the propylene polymer (A) is produced by a continuous multistage polymerization method, there are cases where compositional unevenness occurs between the polymer particles due to the residence time distribution, and the fish eyes of the sheet increase, but by polymerizing in a batch manner, a sheet with fewer fish eyes can be obtained. Therefore, by adopting a batch manner, a sheet with fewer fish eyes can be obtained even though a propylene polymer (a1) having a high molecular weight is used.

≪Manufacturing Conditions≫

In the production of propylene polymers (a1) and (a2), homopolymerization of propylene or polymerization of propylene and an α-olefin having 2 to 8 carbon atoms can be carried out by a known method such as slurry polymerization or bulk polymerization. In addition, it is preferable to use a catalyst for producing polypropylene, which will be described later.

As the conditions for producing a propylene polymer (a1), it is preferable to produce the polymer by bulk polymerization of the raw material monomer in the absence of hydrogen under conditions of a polymerization temperature of preferably 20 to 80°C, more preferably 40 to 70°C, and a polymerization pressure of generally normal pressure to 9.8 MPa, preferably 0.2 to 4.9 MPa.

As the conditions for producing a propylene polymer (a2), it is preferable to produce the polymer by polymerizing the raw material monomer under conditions in which the polymerization temperature is preferably 20 to 80°C, more preferably 40 to 70°C, the polymerization pressure is generally normal pressure to 9.8 MPa, preferably 0.2 to 4.9 MPa, and hydrogen is present as a molecular weight regulator.

≪Catalyst for polypropylene production≫

A catalyst for polypropylene production (hereinafter also simply referred to as “catalyst”) that can be used in the production of a propylene polymer (a1), a propylene polymer (a2), and a propylene polymer (A) can be formed of, for example, a solid catalyst component containing magnesium, titanium, and a halogen as essential components, an organometallic compound catalyst component such as an organoaluminum compound, and an electron-donating compound catalyst component such as an organosilicon compound, and representative examples thereof include the following catalyst components that can be used.

(solid catalyst component)

As a carrier constituting the solid catalyst component, a carrier obtained from metal magnesium, alcohol, halogen and/or halogen-containing compound is preferable.

As the metallic magnesium, magnesium in the form of granules, ribbons, powders, etc. can be used. In addition, it is preferable that the metallic magnesium does not have a coating such as magnesium oxide formed on the surface.

As the alcohol, it is preferable to use a lower alcohol having 1 to 6 carbon atoms, and in particular, if ethanol is used, a carrier that significantly improves the expression of catalytic performance is obtained. The amount of alcohol used is preferably 2 to 100 moles, more preferably 5 to 50 moles, per 1 mole of metal magnesium. One or more types of alcohol can be used.

As the halogen, chlorine, bromine and iodine are preferable, and iodine is more preferable. In addition, as the halogen-containing compound, MgCl ₂ and MgI ₂ are preferable. The amount of the halogen or the halogen-containing compound to be used is such that, with respect to 1 gram atom of metal magnesium, the halogen atom or the halogen atom in the halogen-containing compound is usually 0.0001 gram atom or more, preferably 0.0005 gram atom or more, more preferably 0.001 gram atom or more. The halogen and the halogen-containing compound can be used alone or in combination of two or more.

As a method for obtaining a carrier by reacting metal magnesium, an alcohol, and a halogen and/or a halogen-containing compound, an example of the method is a method in which metal magnesium, an alcohol, and a halogen and/or a halogen-containing compound are reacted under reflux (e.g., about 79°C) until no generation of hydrogen gas is detected (usually 20 to 30 hours). The above reaction is preferably performed in an inert gas atmosphere such as nitrogen gas or argon gas.

When the obtained carrier is used for the synthesis of a solid catalyst component, it may be used in a dried form, or it may be used in a form washed with an inert solvent such as heptane after filtration and separation.

The obtained carrier is close to a granular form, and furthermore, the particle size distribution is sharp. Furthermore, even when each particle is taken, the gap in particle shape is very small. In this case, it is preferable that the sphericity (S) expressed by the following formula (I) is less than 1.60, particularly less than 1.40, and that the particle size distribution index (P) expressed by the following formula (II) is less than 5.0, particularly less than 4.0.

S=(E1/E2) ² ···(I)

In equation (I), E1 represents the projected outline length of the particle, and E2 represents the circumference of a circle equivalent to the projected area of the particle.

P=D90/D10···(II)

In formula (II), D90 refers to the particle diameter corresponding to a mass accumulation fraction of 90%. In other words, it indicates that the mass sum of the particle group smaller than the particle diameter indicated by D90 is 90% of the total mass of the entire particles. D10 refers to the particle diameter corresponding to a mass accumulation fraction of 10%.

The solid catalyst component is usually obtained by contacting the carrier with at least a titanium compound. The contact with the titanium compound may be performed in multiple stages. As the titanium compound, for example, a titanium compound represented by the general formula (III) can be mentioned.

TiX ¹ _n (OR ¹ ) _{4 -n} ···(III)

In formula (III), X ¹ is a halogen atom, particularly a chlorine atom is preferred, R ¹ is a hydrocarbon group having 1 to 10 carbon atoms, preferably a straight-chain or branched alkyl group, and when there are multiple R ¹ s, they may be the same or different, and n is an integer from 0 to 4.

As titanium compounds, specifically, Ti(OiC ₃ H ₇ ) ₄ , Ti(OC ₄ H ₉ ) ₄ , TiCl(OC ₂ H ₅ ) ₃ , TiCl(OiC ₃ H ₇ ) ₃ , TiCl(OC ₄ H ₉ ) ₃ , TiCl ₂ (OC ₄ H ₉ ) ₂ , TiCl ₂ (OiC ₃ H ₇ ) ₂ , and TiCl ₄ can be mentioned, with TiCl ₄ being preferred.

Titanium compounds can be used alone or in combination of two or more.

The solid catalyst component is usually obtained by additionally contacting the carrier with an electron-donating compound. As the electron-donating compound, for example, di-n-butyl phthalate can be mentioned. One or more electron-donating compounds can be used.

When contacting the above carrier with a titanium compound and an electron-donating compound, a halogen-containing silicon compound such as silicon tetrachloride can be contacted. One or two or more halogen-containing silicon compounds can be used.

The solid catalyst component can be prepared by a known method. For example, a method can be exemplified, in which an inert hydrocarbon such as pentane, hexane, heptane or octane is used as a solvent, the carrier, the electron-donating compound and the halogen-containing silicon compound are added to the solvent, and the titanium compound is added while stirring. Usually, the electron-donating compound is added in an amount of 0.01 to 10 mol, preferably 0.05 to 5 mol, per mol of the carrier in terms of magnesium atoms, and the titanium compound is added in an amount of 1 to 50 mol, preferably 2 to 20 mol, per mol of the carrier in terms of magnesium atoms, and the contact reaction is performed under conditions of 0 to 200°C for 5 minutes to 10 hours, preferably 30 to 150°C for 30 minutes to 5 hours. After the reaction is completed, it is preferable to wash the generated solid catalyst component using an inert hydrocarbon such as n-hexane or n-heptane.

In addition, the solid catalyst component may be a component obtained by contacting a liquid magnesium compound and a liquid titanium compound in the presence of an electron-donating compound. The contact with the liquid titanium compound may be performed in multiple stages.

A liquid magnesium compound is obtained, for example, by contacting a known magnesium compound and an alcohol, preferably in the presence of a liquid hydrocarbon medium, to form a liquid. Examples of the magnesium compound include magnesium halides such as magnesium chloride and magnesium bromide. Examples of the alcohol include aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and 2-ethylhexyl alcohol. Examples of the liquid hydrocarbon medium include hydrocarbon compounds such as heptane, octane, and decane. The amount of alcohol used when preparing a liquid magnesium compound is usually 1.0 to 25 mol, preferably 1.5 to 10 mol, per 1 mol of the magnesium compound. One or more types of liquid magnesium compounds can be used.

As the liquid titanium compound, a titanium compound represented by the above-mentioned general formula (III) can be mentioned. The amount of the liquid titanium compound used per 1 mol of magnesium atoms (Mg) contained in the liquid magnesium compound is usually 0.1 to 1000 mol, preferably 1 to 200 mol. The liquid titanium compound can be used alone or in combination of two or more.

Examples of the electron-donating compound include dicarboxylic acid ester compounds such as phthalic acid esters, acid anhydrides such as phthalic anhydride, organosilicon compounds such as dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, and cyclohexylmethyldimethoxysilane, polyethers, acid halides, acid amides, nitriles, and organic acid esters. The amount of the electron-donating compound used per 1 mol of magnesium atoms (Mg) contained in the liquid magnesium compound is usually 0.01 to 5 mol, and preferably 0.1 to 1 mol. The electron-donating compound can be used alone or in combination of two or more.

The temperature at the time of contact is usually -70 to 200°C, preferably 10 to 150°C.

(organic metal compound catalyst component)

Among the catalyst components, an organoaluminum compound is preferable as the organometallic compound catalyst component. As the organoaluminum compound, for example, a compound represented by the general formula (IV) can be mentioned.

AlR ² _n X ² _{3 -n} ···(IV)

In formula (IV), R ² is an alkyl group, cycloalkyl group or aryl group having 1 to 10 carbon atoms, X ² is a halogen atom, preferably a chlorine atom or a bromine atom, and n is an integer of 1 to 3.

As the organic aluminum compounds, specific examples thereof include trialkyl aluminum compounds such as trimethylaluminum, triethylaluminum, and triisobutylaluminum; diethylaluminum monochloride, diisobutylaluminum monochloride, diethylaluminum monoethoxide, and ethylaluminum sesquichloride.

Organoaluminum compounds can be used alone or in combination of two or more.

The amount of the organometallic compound catalyst component to be used is usually 0.01 to 20 moles, preferably 0.05 to 10 moles, per 1 mole of titanium atoms in the solid catalyst component.

(Electron donating compound catalyst component)

As the electron-donating compound component provided to the polymerization system in the catalyst component, an organosilicon compound is preferable. Examples of the organosilicon compound include dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, diethylaminotriethoxysilane, diisopropyldimethoxysilane, and cyclohexylisobutyldimethoxysilane.

Organic silicon compounds can be used alone or in combination of two or more.

The amount of the electron-donating compound component used is usually 0.01 to 20 moles, preferably 0.1 to 5 moles, per 1 mole of titanium atoms in the solid catalyst component.

(Preprocessing)

The above solid catalyst component is preferably used for polymerization after pretreatment such as preliminary polymerization. For example, an inert hydrocarbon such as pentane, hexane, heptane, or octane is used as a solvent, and the solid catalyst component, the organometallic compound catalyst component, and, if necessary, an electron-donating compound component are added to the solvent, stirred, and propylene is supplied to cause a reaction. It is preferable that the propylene be supplied under a partial pressure of propylene higher than atmospheric pressure, and that the pretreatment be performed at 0 to 100°C for 0.1 to 24 hours. After completion of the reaction, it is preferable to wash the pretreated product using an inert hydrocarbon such as n-hexane or n-heptane.

[Propylene polymer (B)]

The propylene polymer (B) is a propylene polymer having a melting point of 120 to 170°C and an intrinsic viscosity [η] measured at 135°C in a tetralin solvent of more than 1.5 dl/g and less than or equal to 5.0 dl/g.

The melting point (Tm) of the propylene polymer (B) is 120 to 170°C, preferably 130 to 170°C, and more preferably 140 to 170°C. From the viewpoints of formability and heat resistance, the above range is preferable. The melting point is measured using a differential scanning calorimeter (DSC).

The ultimate viscosity [η] of the propylene polymer (B) is greater than 1.5 dl/g and less than or equal to 5.0 dl/g, preferably 1.6 to 4.0 dl/g, more preferably 1.7 to 3.5 dl/g. When a propylene polymer (B) having an ultimate viscosity [η] within the above range is used, the productivity during sheet molding is good, and furthermore, the impact resistance of the obtained sheet is good.

The melt flow rate (MFR) of the propylene polymer (B) measured at 230°C and 2.16 kg load is preferably 0.1 to 10 g/10 min, more preferably 0.2 to 5.0 g/10 min, and even more preferably 0.3 to 3.0 g/10 min. When a propylene polymer (B) having an MFR within the above range is used, the productivity at the time of sheet molding is good, and furthermore, the impact resistance of the obtained sheet is good.

The molecular weight distribution (Mw/Mn) of the propylene polymer (B) as measured by gel permeation chromatography (GPC) is preferably greater than 5, more preferably 5.5 to 10, and even more preferably 5.5 to 9. Here, Mn is the number average molecular weight, and Mw is the weight average molecular weight. When the molecular weight distribution (Mw/Mn) of the propylene polymer (B) is within the above range, a sheet having superior rigidity and heat resistance is obtained.

As the propylene polymer (B), the structure thereof is not particularly limited, and examples thereof include a propylene homopolymer, and a copolymer of propylene and α-olefin (excluding propylene). Examples of the copolymer include a propylene/α-olefin random copolymer, a block-type propylene copolymer (a mixture of a propylene homopolymer or a propylene/α-olefin random copolymer and an amorphous or low-crystallization propylene/α-olefin random copolymer), and a random block polypropylene.

As the α-olefins, examples thereof include α-olefins having 2 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Of these α-olefins, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene are preferable. The α-olefins may be used alone or in combination of two or more.

As a propylene polymer (B), a homopolymer of propylene is preferable from the viewpoint of rigidity and impact strength.

The propylene polymer (B) can be produced by polymerizing propylene or copolymerizing propylene with another α-olefin using a catalyst, and also a commercially available polypropylene resin can be used. Examples of the catalyst include a catalyst formed of a solid catalyst component containing the above-mentioned magnesium, titanium, and halogen as essential components, an organometallic compound catalyst component such as an organoaluminum compound, and an electron-donating compound catalyst component such as an organosilicon compound; and a metallocene catalyst using a metallocene compound as one component of the catalyst.

[Other ingredients (additives)]

The above propylene polymer composition may contain additives such as a weather stabilizer, a heat stabilizer, an antistatic agent, a slip agent, an antiblocking agent, an antifogging agent, a nucleating agent, a decomposer, a pigment, a dye, a plasticizer, a hydrochloric acid absorbent, an antioxidant, a crosslinking agent, a crosslinking accelerator, a reinforcing agent, a filler, a softener, a processing aid, an activator, a hygroscopic agent, an adhesive, a flame retardant, a release agent, etc., within a range that does not impair the purpose of the present invention. One or more types of additives may be used.

The above propylene polymer composition may contain a nucleating agent in order to improve transparency, heat resistance, etc. Examples of the nucleating agent include sorbitol compounds such as dibenzylidene sorbitol, organic phosphoric acid ester compounds, rosin acid salt compounds, C4 to C12 aliphatic dicarboxylic acids, and metal salts thereof. Among these, organic phosphoric acid ester compounds are preferable.

One or more types of nucleating agents can be used.

The nucleating agent can be used in an amount of preferably 0.05 to 0.5 parts by mass, more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of the total of the propylene polymer (A) and the propylene polymer (B).

[Preparation and properties of propylene polymer composition]

The above propylene polymer composition can be manufactured by employing any known method, and examples thereof include a method in which the propylene polymer (A) and the propylene polymer (B) and, if necessary, other components are mixed using a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, or the like, or a method in which, after the mixing, the mixture is melt-mixed using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, a roll, or the like, and then granulated or pulverized.

In the above propylene polymer composition, the content of the propylene polymer (A) is 2 to 30 parts by mass, preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, with respect to 100 parts by mass of the total of the propylene polymer (A) and the propylene polymer (B), and the content of the propylene polymer (B) is 70 to 98 parts by mass, preferably 80 to 97 parts by mass, more preferably 85 to 95 parts by mass.

When the content of the propylene polymer (A) is less than 2 parts by mass, the rigidity or heat resistance tends to become insufficient. When the content of the propylene polymer (A) exceeds 30 parts by mass, the transparency of the sheet tends to deteriorate, resulting in poor appearance.

In the present invention, from the viewpoint of rigidity and heat resistance and reduction of fish eye, it is preferable to prepare a propylene polymer composition by mixing a propylene polymer (A) including a propylene polymer (a1) and a propylene polymer (a2) obtained by multi-stage polymerization using a batch method and a propylene polymer (B).

The molecular weight distribution (Mw/Mn) of the above propylene polymer composition as measured by gel permeation chromatography (GPC) is preferably 6.0 or more, more preferably 6.2 or more, still more preferably 6.4 or more, and the upper limit is not particularly limited, but is, for example, 15 or less. The molecular weight distribution (Mz/Mw) of the above propylene polymer composition as measured by GPC is preferably 3.0 or more, more preferably 3.2 or more, still more preferably 3.5 or more, and the upper limit is not particularly limited, but is, for example, 8 or less. Here, Mn is the number average molecular weight, Mw is the weight average molecular weight, and Mz is the z-average molecular weight.

In the present invention, since a propylene polymer (a1) having a high molecular weight is used, the molecular weight distribution of the propylene polymer composition is widened. Therefore, when the propylene polymer composition is formed into a sheet, the degree of orientation in the MD direction of the forming is increased, and it is assumed that the sheet is highly crystallized due to the orientation, and a sheet having excellent rigidity and heat resistance is obtained.

The relaxation time (strain rate ω=1.0 radian/sec) of the above propylene polymer composition, obtained using a viscoelasticity measuring device under the conditions of a temperature of 175°C, a strain of 5%, and a measurement angular frequency of 10 ^-2 to 10 ² s ^-1, is preferably 1.0 second or more, and further, the molecular weight distribution index (PDI) is preferably 10 or more, and more preferably, the PDI is 12 or more.

Here, when the angular frequency at which the storage modulus G' becomes 2×10 ² Pa is ω1 and the angular frequency at which it becomes 2×10 ⁴ Pa is ω2, the index expressed as ω2/10ω1 is called the molecular weight distribution index (PDI).

Relaxation time is obtained from the ratio of the storage modulus to the loss modulus at a specific angular frequency, and is an indicator of the ease of relaxation of the molecular chain (affected by both the MFR and the molecular weight distribution). PDI has a larger value as the non-Newtonian property increases, and is an indicator of the molecular weight distribution.

When the relaxation time is 1.0 second or more and the molecular weight distribution index is 10 or more, when the propylene polymer composition is formed into a sheet, the orientation in the MD direction by the high molecular weight component tends to be large, and the effect of improving high rigidity and high heat resistance by orientation crystallization tends to be large.

[Sheet Composition]

The non-foaming sheet of the present invention may be a single-layer sheet formed of a layer formed from the propylene-based polymer composition, or may be a laminated sheet having a layer formed from the propylene-based polymer composition. The non-foaming sheet is used, for example, as a packaging material for foods, beverages, industrial parts, sundry goods, toys, daily necessities, office supplies, medical supplies, and the like.

In the case of a laminated sheet, it may be a laminated sheet having two or more layers formed from the above-mentioned propylene-based polymer composition, or it may be a laminated sheet having one or more layers formed from the above-mentioned propylene-based polymer composition and one or more other layers. By forming a laminated configuration, various functions can be additionally imparted to the sheet. Examples of the methods used in that case include a coextrusion method and an extrusion coating method. Examples of the other layer include a barrier layer for gases such as oxygen or water vapor, a sound-absorbing layer, a light-shielding layer, an adhesive layer, an adhesive layer, a coloring layer, a conductive layer, and a layer containing a regenerated resin. Specific examples of the material forming the other layer include an olefin-based polymer composition other than the above-mentioned propylene-based polymer composition, a gas barrier resin composition, and an adhesive resin composition.

The thickness of the non-foaming sheet of the present invention is usually 200 μm or more, preferably 200 μm to 5.0 mm, and more preferably 300 μm to 3.0 mm.

The non-foamed sheet of the present invention has excellent rigidity and heat resistance. Specifically, the non-foamed sheet of the present invention has a high tensile modulus at room temperature and also a high tensile modulus at high temperature. In addition, the non-foamed sheet has excellent heat resistance because the melting point and fusion enthalpy of the sheet are high. In addition, the non-foamed sheet has a low occurrence of fish eyes in one embodiment.

Examples of methods for manufacturing sheets include extrusion molding methods such as the T-die method or inflation method, compression molding methods, calendar molding methods, and flexible methods.

Sheet molding can be performed, for example, as follows. The above-described components constituting the above-described propylene polymer composition may be directly charged into a hopper or the like of a sheet molding machine, or the above-described components may be mixed in advance using a ribbon blender, a Banbury mixer, a Henschel mixer, a super mixer, or the like, or additionally, a single-screw or twin-screw extruder, a roll or the like mixer may be used to melt-mix, thereby obtaining a propylene polymer composition, and then sheet molding may be performed.

If a specific example of manufacturing a sheet is explained using the T-die method, each of the above components is fed into an extruder, melted and mixed at a temperature of usually 180 to 280°C, preferably 200 to 270°C, then extruded into a sheet form from the die lip of the T-die, this molten sheet is cooled, and taken up by a take-up machine using a nip roll or the like, thereby obtaining a sheet.

Examples of cooling methods for the molten sheet include a cooling method using a roll and air cooling using an air knife method or an air chamber method, a narrow pressure cooling method using a polishing roll method, a swing roll method, a belt casting method, etc., and a contact cooling method using a refrigerant such as a water cooling method.

In the present invention, a molded article can be obtained by processing the non-foamed sheet. For example, a molded article can be obtained by molding the non-foamed sheet into a shape of a container (e.g., a bottle, a cup, a tray, a bowl) or a lid by a conventionally known molding method such as vacuum molding, pressure molding, extrusion molding, or plug-assist molding. As the molding conditions, conventionally known molding conditions can be adopted. The molded article also has excellent rigidity and heat resistance.

Example

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. Meanwhile, the measurement and evaluation of various properties of the polymer, polymer composition, sheet, and container obtained in each example were performed as follows.

(1) In the manufacturing example, the mass fraction of the propylene polymer obtained in the first stage (equivalent to propylene polymer (a1)) and the propylene polymer obtained in the second stage (equivalent to propylene polymer (a2)) were obtained from the sequential amount of heat of reaction generated during polymerization.

(2) The ultimate viscosity [η] (dl/g) was measured at 135°C in a tetralin solvent. Meanwhile, the ultimate viscosity [η] ₂ of the propylene polymer (equivalent to the propylene polymer (a2)) obtained in the second stage is a value calculated from the following formula.

[η] ₂ =([η] _total ×100-[η] ₁ ×W ₁ )/W ₂

[η] _total : Ultimate viscosity of the entire propylene polymer

[η] ₁ : The ultimate viscosity of the propylene polymer obtained in the first stage

W ₁ : Mass fraction (%) of propylene polymer obtained in the first stage

W ₂ : Mass fraction (%) of propylene polymer obtained in the second stage

(3) Melt flow rate (MFR) (g/10 min) was measured at a measurement temperature of 230°C and a load of 2.16 kgf (21.2 N) in accordance with JIS-K7210.

(4) Melting point

The melting point of the propylene polymer (B) was measured using a differential scanning calorimeter (DSC, PerkinElmer). Here, the endothermic peak in the third step was defined as the melting point.

<Sample writing conditions>

Forming method: Press forming

Mold: thickness 0.2mm

(Wrap the sample with aluminum foil and press-form using a mold)

Molding temperature: 240℃

Press pressure: 300kg/ ^cm2 , Press time: 1 minute

After press forming, cool the sheet with ice water, and seal about 0.4 g of the sheet in the measuring container below.

Measuring vessel: DSC PANS 10μl BO-14-3015

DSC COVER BO14-3003

<Measurement Conditions>

Step 1: Increase the temperature from 30℃ to 230℃ at 10℃/min and maintain for 10 minutes.

Step 2: Cool to 30℃ at 10℃/min.

Step 3: Increase the temperature to 230℃ at 10℃/min.

(5) The average molecular weight (number average molecular weight Mn, weight average molecular weight Mw, z average molecular weight Mz) was obtained by gel permeation chromatography (GPC) using the following equipment and conditions, and the molecular weight distribution (Mw/Mn, Mz/Mw) was obtained.

GPC Measuring Device

Gel permeation chromatograph HLC-8321 GPC/HT type (Tosoh Corporation)

Interpretation device

Data processing software Empower 3 (Waters)

Measurement conditions

Column: TSKgel GMH6-HT×2 + TSKgel GMH6-HTL×2

(All 7.5mmI.D.x30cm, made by Dososa)

Column temperature: 140℃

Mobile phase: o-Dichlorobenzene (containing 0.025% BHT)

Detector: Parallel Refractometer

Flow rate: 1.0mL/min

Sample concentration: 0.1% (w/v)

Injection volume: 0.4mL

Sampling time interval: 1s

Column correction: Monodisperse polystyrene (Tosos)

Molecular weight conversion: PP conversion/universal correction method (viscosity conversion factor of PS (polystyrene) K _PS = 0.000138 dl/g,

α _PS = 0.700, viscosity conversion factor of PP (polypropylene) K _PP = 0.000242 dl/g, α _PP = 0.707)

(6) Relaxation time (G'/G"/ω(τ))

Measurements were made using a viscoelasticity measuring device (Anton Paas) under the following conditions.

Sample: A 25mm diameter, 1mm thick disc was produced using a press molding machine.

(Pressurized at 230℃, 981N(100kgf) for 3 minutes, then cooled at 30℃, 981N(100kgf) for 3 minutes)

Measurement conditions: temperature 175℃, strain 5%, measurement angular frequency 10 ^-2 ∼10 ² s ^-1 .

(7) Molecular weight distribution index (PDI)

When measuring under the same conditions using the above viscoelasticity measuring device, when the angular frequency at which the storage elastic modulus G' becomes 2×10 ² Pa is ω1 and the angular frequency at which it becomes 2×10 ⁴ Pa is ω2, the index expressed as ω2/10ω1 is taken as the molecular weight distribution index PDI.

(8) Elasticity of container

The tensile modulus (MPa) was measured according to the method of JIS K7113. The measurement was performed in the depth direction of the container at 23°C.

(9) Container deformation load

The maximum load (g) was measured when the side of the container was pushed in by 5 mm.

(10) Sheet DSC measurement

The melting point (Tm) of the sheet was measured using a differential scanning calorimeter (DSC, PerkinElmer). Here, the endothermic peak in the first step was defined as the melting point (Tm), and the area obtained from the endothermic peak curve was defined as the enthalpy of fusion (ΔHm).

<Sample writing conditions>

I used a sheet.

<Measurement Conditions>

Step 1: Increase the temperature from 30℃ to 230℃ at 10℃/min and maintain for 10 minutes.

(11) Sheet elasticity

The tensile modulus (MPa) was measured according to the method of JIS K7113. Meanwhile, the measurement was performed under the conditions of 23°C and 60°C for the extrusion direction (MD) of the molding and the direction perpendicular to the MD (TD).

〔Manufacturing Example 1〕

(1) Preparation of magnesium compounds

A reactor equipped with a stirrer (volume: 500 L) was sufficiently replaced with nitrogen gas, 97.2 kg of ethanol, 640 g of iodine, and 6.4 kg of metallic magnesium were charged, and the reaction was conducted under reflux conditions with stirring until no more hydrogen gas was generated from within the system, thereby obtaining a solid reaction product. The reaction solution containing the solid reaction product was dried under reduced pressure, thereby obtaining the target magnesium compound (support for the solid catalyst).

(2) Preparation of solid titanium catalyst component

In a reactor equipped with a stirrer (volume: 500 L) sufficiently purged with nitrogen gas, 30 kg of the above-mentioned magnesium compound (not pulverized), 150 L of purified heptane (n-heptane), 4.5 L of silicon tetrachloride, and 5.4 L of di-n-butyl phthalate were added. Maintaining the inside of the system at 90°C and stirring, 144 L of titanium tetrachloride was added, and after reacting at 110°C for 2 hours, the solid component was separated and washed with purified heptane at 80°C. In addition, 228 L of titanium tetrachloride was added, and after reacting at 110°C for 2 hours, the solid component was sufficiently washed with purified heptane, to obtain a solid titanium catalyst component.

(3) Preparation of pre-polymerization catalyst

To 200 mL of heptane, 10 mmol of triethylaluminum, 2 mmol of dicyclopentyldimethoxysilane, and 1 mmol of the solid titanium catalyst component obtained in the above (2) were added in terms of titanium atoms. The internal temperature was maintained at 20°C, and propylene was continuously introduced while stirring. After 60 minutes, stirring was stopped, and as a result, a pre-polymerization catalyst slurry in which 4.0 g of propylene was polymerized per 1 g of the solid titanium catalyst component was obtained.

(4) This polymerization

In a 600-liter autoclave, 336 liters of propylene were charged, and the temperature was raised to 60°C. Thereafter, 8.7 mL of triethylaluminum, 11.4 mL of dicyclopentyldimethoxysilane, and 2.9 g of the prepolymerization catalyst slurry obtained in (3) above as a solid titanium catalyst component were charged, and polymerization was initiated. 75 minutes after the initiation of polymerization, the temperature was lowered to 50°C over 10 minutes (end of first-stage polymerization).

The ultimate viscosity [η] of the propylene polymer (a1-1) polymerized under the same conditions as in the first stage was 11 dl/g.

After the temperature was lowered, hydrogen was continuously added so that the pressure was constant at 3.3 MPaG, and polymerization was performed for 151 minutes. Then, the vent valve was opened, and unreacted propylene was purged through the flow meter (end of the second stage polymerization).

In this way, 51.8 kg of powdered propylene polymer was obtained. The proportion of the propylene polymer (a1-1) produced by the first-stage polymerization in the propylene polymer, as calculated from the material balance, was 25 mass%, the proportion of the propylene polymer (a2-1) produced by the second-stage polymerization was 75 mass%, and the ultimate viscosity [η] was 0.99 dl/g.

To this propylene polymer, 2,000 ppm of Irganox 1010 (manufactured by BASF), 2,000 ppm of Irgafos 168 (manufactured by BASF), 1,000 ppm of Sandostav P-EPQ (manufactured by Clariant Japan) as antioxidants, and 1,000 ppm of calcium stearate as a neutralizer were added, and melt-kneading was performed using a twin-screw extruder to obtain a pellet-shaped propylene polymer (A-1). The MFR of the propylene polymer (A-1) thus finally obtained was 1.2 g/10 min.

[Example 1]

In Manufacturing Example 1, the propylene polymer (A-1) obtained and the propylene polymer (B) E-203GV (Prime Polypro E-203GV, manufactured by Prime Polymer Co., Ltd.) were mixed at a mass ratio of 5:95, and a total of 100 parts by mass of these resins were melt-extruded at a resin temperature of 260°C using an extruder (TEM-41SS manufactured by Toshiba Machinery) to obtain a sheet-shaped resin composition. This sheet-shaped resin composition was cooled by sandwiching it between a first cooling roll and a second cooling roll (respective roll setting temperatures of 35°C and 75°C), and taken up at a speed of 0.8 m/min to obtain a sheet having a thickness of 1.5 mm. Using the sheet, a cup container was created by heating it at an upper and lower heater setting temperature of 450°C using FK-0431-10 manufactured by Asano Laboratory Co., Ltd., and various evaluations were performed.

[Examples 2-3]

The same procedure as Example 1 was followed, except that the mixing composition was changed as described in Table 1.

[Example 4]

The same procedure as in Example 2 was carried out, except that E-200GV (Prime Polymer, Prime Polypro E-200GV) was used instead of E-203GV as the propylene polymer (B).

[Comparative examples 1-2]

In Comparative Example 1, E-203GV (Prime Polymer, Prime Polypro E-203GV) was used, and in Comparative Example 2, E-200GV (Prime Polymer, Prime Polypro E-200GV) was used, and sheets and cup containers were produced under the molding conditions shown in Example 1, and various evaluations were performed.

The various physical properties of E-203GV and E-200GV are as listed in Table 1.

Claims (8)

A non-foaming sheet having a layer formed of a propylene polymer composition,
The above propylene polymer composition,
A propylene polymer (A) comprising 20 to 50 mass% of a propylene polymer (a1) having an intrinsic viscosity [η] of 10 to 12 dl/g as measured in a tetralin solvent at 135°C, and 50 to 80 mass% of a propylene polymer (a2) having an intrinsic viscosity [η] of 0.5 to 1.5 dl/g as measured in a tetralin solvent at 135°C (wherein the total amount of the propylene polymer (a1) and the propylene polymer (a2) is 100 mass%), and a propylene polymer (B) having a melting point of 120 to 170°C and an intrinsic viscosity [η] of more than 1.5 dl/g and 5.0 dl/g as measured in a tetralin solvent at 135°C,
A non-foaming sheet characterized in that the content of the propylene polymer (A) is 2 to 30 parts by mass and the content of the propylene polymer (B) is 70 to 98 parts by mass, based on 100 parts by mass of the total of the propylene polymer (A) and the propylene polymer (B). In paragraph 1,
A non-foaming sheet having a molecular weight distribution (Mw/Mn) of 6.0 or more as measured by gel permeation chromatography (GPC) of the above propylene polymer composition. In paragraph 1,
A non-foamed sheet having a melt flow rate (MFR) of 0.1 to 10 g/10 minutes as measured at 230°C and a load of 2.16 kg of the above propylene polymer (B). In paragraph 1,
A non-foamed sheet having a molecular weight distribution (Mw/Mn) of the above propylene polymer (B) exceeding 5 as measured by gel permeation chromatography (GPC). In paragraph 1,
Non-foamed sheet with a thickness of 200 μm or more. In paragraph 1,
A non-foaming sheet which is a single-layer sheet formed of a layer formed from the above propylene-based polymer composition. In paragraph 1,
A non-foaming sheet which is a laminated sheet having a layer formed from the above propylene polymer composition. A container formed from a non-foaming sheet according to any one of claims 1 to 7.