JP2004291626A - Propylene-based resin made multi-layered foamed sheet and returnable box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylene-based resin made multi-layered foamed sheet having a high foaming ratio and beautiful appearance. <P>SOLUTION: The propylene-based resin made multi-layered foamed sheet has a resin layer (1) and a resin layer (2) on a propylene-based resin made foamed sheet (3) each obtained by a co-extrusion method using a T-die. The foaming ratio of the foamed layer is not less than 2.5. The foamed layer (3), the resin layer (1) and the resin layer (2) contain not less than 10wt.% of a linear propylene-based polymer (a) satisfying MT(190)≥7.52×MFR(230)<SP>(-0.576)</SP>wherein MT(190) is melt tension at 190°C and MFR(230) is a melt flow rate at 230°C. Further the resin layer (1) and the resin layer (2) contain a filler (b). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a multi-layer foamed sheet made of a propylene-based resin having a high expansion ratio and a beautiful appearance, and a box made of the multi-layered foamed sheet made of a propylene-based resin.

BACKGROUND ART Foam sheets made of propylene-based resin are used for packaging, mail boxes, partition boards, food containers, stationery, building materials, automobile interior materials, etc., utilizing their mechanical properties, light weight, heat resistance, oil resistance, and the like. When a propylene-based resin foam sheet is used for various purposes, it may be used as a multilayer foam sheet by laminating a film according to the purpose on the surface of the foam layer, or laminating a non-foam layer on the foam layer. Many. Such a multi-layer foamed sheet made of a propylene-based resin includes a non-foamed layer made of a polypropylene homopolymer containing a filler and a polypropylene homopolymer containing no filler on both sides of a foamed layer made of a polypropylene block copolymer having a double expansion ratio. There is disclosed a multilayer foam sheet in which polymer non-foam layers are sequentially laminated (see Patent Document 1).

JP-A-7-223291

However, the multilayer foam sheet as described above has a low expansion ratio, and in the case of obtaining a foam sheet with a high expansion ratio, poor appearance often occurs.

An object of the present invention is to provide a propylene-based resin multilayer foam sheet having a high expansion ratio and a beautiful appearance, and a box made of the propylene-based resin multilayer foam sheet.

That is, the present invention relates to a propylene-based resin multilayer foam sheet having a resin layer (1) and a resin layer (2) on the surface of a propylene-based resin foam layer (3) obtained by a co-extrusion method using a T-die. The foaming ratio of the foamed layer (3), the resin layer (1) and the resin layer (2) is not less than the melt tension at 190 ° C. (MT (190)) at 230 ° C. The melt flow rate (MFR (230)) contains at least 10% by weight of a linear propylene polymer (A) satisfying MT (190) ≧ 7.52 × MFR (230) ^(−0.576). In addition, the resin layer (1) and the resin layer (2) are a propylene-based resin multilayer foam sheet containing a filler (a). The present invention also provides a box made of the propylene-based resin multilayer foam sheet.

The propylene resin multilayer foam sheet of the present invention is a propylene resin multilayer foam sheet having a high expansion ratio and a beautiful appearance. Further, the box made of the propylene-based resin multilayer foam sheet of the present invention has a high expansion ratio and a beautiful appearance.

The propylene-based resin multilayer foam sheet of the present invention has a resin layer (1) and a resin layer (2) on the surface of a propylene-based resin foam layer (3), and has a foam layer (3), a resin layer (1) and The resin layer (2) is such that the melt tension (MT (190)) at 190 ° C. and the melt flow rate (MFR (230)) at 230 ° C. satisfy the following equation (1). At least 10% by weight.
MT (190) ≧ 7.52 × MFR (230) ^(−0.576) [Equation 1]

The linear propylene-based polymer (A) in the present invention is a polymer having a degree of branching index [A] defined by the following formula 2 of 0.90 or more.

Branching degree index [A] = [η] Br / [η] Lin [Equation 2]
Here, [η] Br is the intrinsic viscosity of the polypropylene sample to be measured, and [η] Lin is the weight of the isotactic semi-crystalline linear polypropylene having substantially the same weight average molecular weight as the measurement sample. Intrinsic viscosity. Such a linear propylene polymer (A) can be polymerized using a solid catalyst (Ziegler-Natta catalyst) containing Ti atom, Mg atom, and halogen atom.

The linear propylene-based polymer (A) is a process for producing a crystalline propylene polymer portion (A) having an intrinsic viscosity of 5 dl / g or more, and a crystalline propylene polymer portion (B) having an intrinsic viscosity of less than 3 dl / g. A) having a limiting viscosity of less than 3 dl / g and a proportion of the crystalline propylene polymer portion (A) of 0.05% by weight or more and less than 35% by weight. A propylene-based polymer (T) is preferred from the viewpoint of foamability. Such a linear propylene polymer (T) can be polymerized by the following method.

The linear propylene polymer (T) is a polymer obtained by a polymerization method including a step of producing (A) and a step of producing (B). For example, a batch polymerization method in which (A) is polymerized in the first step, and then (B) is polymerized in the same polymerization tank as that in which (A) is polymerized in the second step, or two or more polymerization tanks are used. They are arranged in series, and are obtained by a method such as a continuous polymerization method in which (A) is polymerized as the first step, the product is transferred to the next polymerization tank, and (B) is polymerized as the second step in the polymerization tank. It is a polymer. In the case of a continuous polymerization method, the number of polymerization tanks in each of the first and second stages may be one or two or more.

In order to obtain a foam having a high expansion ratio and a beautiful appearance, the linear propylene polymer (T) preferably has a higher melt strength, and from this viewpoint, the intrinsic viscosity of (A) is at least 5 dl / g. Is preferably 6 dl / g or more, more preferably 7 dl / g or more. The intrinsic viscosity of (A) is preferably as high as possible, and the upper limit is not particularly limited, but is usually less than 15 dl / g. The intrinsic viscosity of (A) is more preferably 6 to 13 dl / g, particularly preferably 7 to 11 dl / g.

The content of the crystalline propylene polymer portion (A) in the linear propylene polymer (T) is preferably 0.05% by weight or more, and more preferably 0.3% by weight or more from the viewpoint of melt strength. More preferred. From the viewpoint of elongation characteristics, the amount of the crystalline propylene polymer portion (A) is preferably as small as possible, as long as it has a sufficient melt strength to obtain a foam, usually less than 35% by weight, and preferably 20% by weight. % Is more preferable. The proportion of the crystalline propylene polymer portion (A) in the linear propylene polymer (T) can be set to a predetermined amount by controlling the polymerization conditions.

From the viewpoint of fluidity and extrudability, the intrinsic viscosity of the crystalline propylene polymer portion (B) in the linear propylene polymer (T) is preferably less than 3 dl / g.

The intrinsic viscosity of the entire linear propylene polymer (T) is also preferably less than 3 dl / g from the viewpoint of fluidity and extrudability. In the MFR, the linear propylene-based polymer (T) preferably has a range of 5 g / 10 min or more and 30 g / 10 min or less. If the MFR of the linear propylene-based polymer (T) is too high, the melt tension required for foaming cannot be maintained. If the MFR is too low, the effect on extrusion processability, specifically, heat generation due to shearing, and rise in resin temperature may occur. A large impact. The MFR of the linear propylene-based polymer (T) is more preferably 8 g / 10 min or more and 25 g / 10 min or less, and still more preferably 10 g / 10 min or more and 20 g / 10 min or less.

In order to obtain a foam sheet with a more beautiful appearance, the molecular weight distribution of the entire linear propylene-based polymer (T) is preferably less than 10. The molecular weight distribution is the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by GPC measurement.

When the linear propylene polymer (T) is obtained by continuously polymerizing the crystalline propylene polymer portion (A) and the crystalline propylene polymer portion (B), the intrinsic viscosity of (B) is (B) The above conditions can be achieved by appropriately setting the manufacturing conditions of (1). The intrinsic viscosity of the (B) is crystalline in intrinsic viscosity [eta] _A, linear propylene polymer having an intrinsic viscosity of the linear propylene polymer _(T) [η] T and (A) (T) It can be determined by the following equation 3 using the content (% by weight) of each of the propylene polymer portions (A) and (B).
[Η] _B = ([η] _T × 100− [η] _A × W _A ) ÷ W _B [Equation 3]
[Η] _T : intrinsic viscosity (dl / g) of propylene-based polymer (T)
[Η] _A : intrinsic viscosity (dl / g) of the crystalline propylene polymer portion (A)
W _A : Content (% by weight) of crystalline propylene polymer portion (A)
W _B: the content of the crystalline propylene polymer portion (B) (wt%)

In addition, from the viewpoint of the melt strength of the propylene-based polymer (T), it is more preferable that the intrinsic viscosity [η] _A (dl / g) and the content W _A (% by weight) of ( _A ) satisfy the following Expression 4. .
W _A ≧ 400 × EXP (−0.6 × [η] _A ) [Equation 4]

The crystalline propylene polymer portions (A) and (B) are each a crystalline propylene polymer portion having a polypropylene crystal structure, and are composed of a propylene homopolymer or propylene with an amount of ethylene that does not lose crystallinity. And / or copolymers with comonomers such as α-olefins are preferred. Examples of the α-olefin include 1-butene, 4-methyl-1-pentene, 1-octene, 1-hexene and the like. The amount that does not lose crystallinity differs depending on the type of comonomer. For example, in the case of ethylene, the amount of ethylene units in the copolymer is usually 10% by weight or less, and in the case of other α-olefins such as 1-butene. The amount of α-olefin units in the copolymer is usually 30% by weight or less. (A) and (B) may have the same composition or different compositions. (A) and (B) may be combined in a block manner. Further, in the linear propylene-based polymer (T), a polymer in which (A) and (B) are bonded in a block manner and other (A) and (B) may coexist.

The crystalline propylene polymer portion (B) may be a polymer portion in which an amorphous ethylene / α-olefin copolymer is dispersed in a crystalline propylene polymer. The linear propylene polymer (T) can be produced using a Ziegler-Natta catalyst, and a specific production method is described in JP-A-11-228629.

When the foamed layer (3) contains the linear propylene polymer (A) as described above in an amount of 10% by weight or more, a multilayer foamed sheet having a high foaming ratio and a beautiful appearance can be obtained. The amount of the linear propylene polymer (A) contained in the foamed layer (3) is preferably at least 20% by weight, more preferably at least 30% by weight. As the content of the linear propylene-based polymer (a) is larger, the expansion ratio is higher, and a foam sheet with beautiful appearance can be obtained.

The expansion ratio of the foam layer (3) in the propylene-based resin multilayer foam sheet of the present invention is 2.5 times or more, preferably 3 times or more, more preferably 3.5 times or more, and more preferably 4 times or more. is there.

The resin layer (1) and the resin layer (2) contain 10% by weight or more of the above-mentioned propylene-based polymer (A) and contain a filler (A), so that gas escape from the foamed layer (3). , And a multi-layer foamed sheet made of a propylene-based resin having a high expansion ratio and a beautiful appearance can be obtained. The content of the propylene-based polymer (A) in the resin layer (1) and the resin layer (2) is preferably 20% by weight or more, and more preferably 30% by weight or more. Further, the content of the filler (a) in the resin layer (1) and the resin layer (2) is preferably from 10 to 50% by weight, and more preferably from 20 to 50% by weight. By setting the content of the filler (a) as described above, a multilayer foam sheet made of a propylene-based resin having an excellent balance between bending rigidity and impact strength can be obtained.

The content of the propylene polymer (A) in the resin layer (1) and the content of the propylene polymer (A) in the resin layer (2) may be the same or different. The content of the filler (a) in the resin layer (1) and the content of the filler (a) in the resin layer (2) may be the same or different.

As the filler (a) contained in the resin layer (1) and the resin layer (2), a known filler can be used. For example, talc, basic magnesium sulfate, silica, diatomaceous earth, calcium carbonate, magnesium carbonate , Barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, calcium silicate, zeolite, mica, clay, wollastonite, hydrotalcite, magnesium oxide, zinc oxide, zinc stearate, calcium stearate, synthetic aluminosilicate And various fibers such as aluminum phosphate, carbon black, white carbon, graphite, glass fiber, pulp, and asbestos fiber. It is preferable to use talc or basic magnesium sulfate from the viewpoint of improving the bending rigidity. The particle size and aspect ratio of the filler used are not particularly limited, but it is preferable to use a filler having a large aspect ratio from the viewpoint of reducing outgassing from the foamed layer (3). It is considered that by using a filler having a large aspect ratio, the filler is oriented in the extrusion direction by shearing in the die, and has an effect of suppressing outgassing from the foamed layer (3).

The resin other than the linear propylene-based polymer (A) constituting the resin layer (1), the resin layer (2) and the foamed layer (3) may be a propylene-based resin such as homopolypropylene, random polypropylene or block polypropylene. Just fine. Further, other olefin-based resins such as ethylene-based resins such as low-density polyethylene and high-density polyethylene may be contained to such an extent that the effects of the present invention are not impaired. From the viewpoint of improving impact resistance, it is preferable to include block polypropylene or low-density polyethylene.

The foaming agent used to form the foamed layer (3) is not particularly limited, and a known foaming agent can be used. For example, as the physical foaming agent, carbon dioxide gas, nitrogen gas, air, propane, butane, pentane, hexane, dichloroethane, dichlorodifluoromethane, dichloromonofluoromethane, trichloromonofluoromethane can be mentioned, nitrogen gas, carbon dioxide gas, It is preferable to use a safe and environmentally friendly inorganic gas such as air, and it is more preferable to use carbon dioxide gas because of its high solubility in a propylene-based resin. When carbon dioxide gas is used, it is preferable to mix it with a propylene-based resin in a supercritical state of 7.4 MPa or more and 31 ° C. or more from the viewpoint of diffusion into the resin and solubility.

Examples of the chemical blowing agent used in the present invention include baking soda, a mixture of baking soda and citric acid, sodium citrate, an organic acid such as stearic acid, azodicarbonamide, tolylene diisocyanate, 4,4'diphenylmethane diisocyanate and the like. Azo such as isocyanate compounds, azobisbutyronitrile, barium azodicarboxylate, diazoaminobenzene, trihydrazinotriazine, benzenesulfonyl hydrazide, P, P'-oxybis (benzenesulfonyl hydrazide), Hydrazine derivatives such as toluene / sulfonyl / hydrazide; nitroso compounds such as N, N'-dinitroso / pentamethylene / tetramine; N, N'-dimethyl-N, N'-dinitroso / terephthalamide; P-toluene / sulfonyl Semicarbazide, can be given other azide compound or a triazole compound of semicarbazide compounds such as 4,4 'oxybisbenzenesulfonyl semicarbazide. Particularly, baking soda, citric acid and azodicarbonamide are preferable.

The above physical foaming agents and chemical foaming agents may be used alone or in combination of two or more. When a chemical foaming agent is used, a foaming aid may be used in combination to adjust the decomposition temperature and decomposition rate. For example, since azodicarbonamide alone has a high decomposition temperature of about 200 ° C., when processing at a low temperature is desired, a small amount of zinc oxide, zinc stearate, urea, or the like may be added as a foaming aid.

When using a physical foaming agent, a cell nucleating agent can be added. Foam nucleating agents include talc, silica, diatomaceous earth, calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, calcium silicate, zeolite, mica, clay, wollastonite, hydrotalcite And polymer beads such as magnesium oxide, zinc oxide, zinc stearate, calcium stearate, and PMMA, synthetic aluminosilicate, and the above-mentioned chemical foaming agents.

The multilayer foamed sheet made of a propylene-based resin of the present invention may have the resin layer (1) and the resin layer (2) on the surface of the propylene-based resin foamed layer (3). That is, it is a multilayer foam sheet laminated in the order of resin layer (1) / foam layer (3) / resin layer (2). The multilayer foamed sheet made of a propylene-based resin of the present invention may have another layer on the resin layer (1) and / or the resin layer (2). The multilayer foamed sheet made of a propylene-based resin of the present invention is a propylene-based resin formed by laminating a resin layer (4) / resin layer (1) / foamed layer (3) / resin layer (2) / resin layer (5) in this order. It is preferably a multi-layer foamed sheet.

The resin constituting the resin layer (4) and the resin layer (5) is not particularly limited, but is preferably a propylene-based resin, and may contain a linear propylene-based polymer (A). . Further, the resin layer (4) and the resin layer (5) may be made of the same resin, or may be made of different resins.

All the layers constituting the multi-layer foamed sheet made of propylene-based resin of the present invention may contain various additives as necessary. In particular, when the resin layer (4) and the resin layer (5) are surface layers, at least one of these layers is used for applications such as packaging, mail boxes, partition boards, food containers, stationery, building materials, and automobile interior materials. It is preferable to include an additive or a modified resin for expressing a corresponding function. Examples of such additives and modified resins include antistatic agents, flame retardants, fillers, antioxidants, copper damage inhibitors, weathering agents, ultraviolet absorbers, lubricants, pigments, and foaming agents.

For example, in the case of applications such as food containers, packaging and mail boxes where hygiene is important, the resin layer (4) and / or the resin layer (5) may contain an antistatic agent to prevent dust adhesion. preferable. Further, in the case where washing is repeated and used for a long time, it is preferable to use a polymer type antistatic agent rather than a low molecular type antistatic agent. Examples of the polymer type antistatic agent include polyether-based resins and polyamide-based resins.
Further, when a skin material is laminated on the multilayer foam sheet of the present invention and used for an automobile interior material or the like, the resin layer (4) and / or the resin layer (5) in order to exhibit adhesiveness to the skin material. Preferably contains an adhesive resin.

The multilayer foamed sheet made of a propylene-based resin of the present invention is obtained by a co-extrusion method using a T-die. The resin and the foaming agent constituting each layer are melt-kneaded using an extruder, laminated and integrated in a feed block or a T-die connected to the extruder, and coextruded into the atmosphere to obtain a flat molten sheet. The plate-shaped molten sheet is brought into contact with a number of rolls whose cooling temperature is set immediately after the multilayer T-die, or is passed while making contact between two plate-shaped flat plates whose cooling temperature is adjusted. After cooling by a known method, a take-off machine provided with a nip roll takes it off and cuts it into a predetermined size with a cutter to produce a propylene-based resin multilayer foam sheet.

As the extruder, a single-screw or multi-screw extruder can be used, and a tandem extruder combining a plurality of extruders can also be used. The extruder used for kneading the resin and the foaming agent constituting the foamed layer (3) is preferably a twin-screw extruder, which has a large amount of extrusion per one rotation of the screw and can obtain a predetermined amount of extrusion at a low rotation. It is more preferable to use an extruder having a structure that generates less shear heat due to screw rotation. A cooling medium may be circulated through the screw body to control the temperature.

A gear pump is provided between each extruder and the feed block or the multilayer T-die, and a fixed-quantity feeder is provided for raw material supply, and feedback to the screw or gear pump rotation speed and raw material supply amount is used to control the gear pump inlet pressure at a constant level. This system is also effective in stabilizing the extruded foam state.
It is also effective to stabilize the foaming state by inserting a static mixer or the like into the adapter that connects each extruder to the feed block or the multilayer T-die so as to make the resin temperature uniform.

When a physical foaming agent is used, the extruder for the foaming layer (3) has a structure in which the foaming agent can be pressed into the melted resin. It is necessary that the resin and the foaming agent are sufficiently mixed and homogenized, and the resin temperature can be controlled to be appropriate for foaming.

The method for laminating and joining the respective molten resins is not particularly limited, but two examples of a multi-manifold system and a feed block system are generally exemplified.
When the structure of the multilayer foam sheet of the present invention is composed of three types and five layers, a multi-manifold system having five layers of manifolds in a T-die may be used. A combined scheme is preferred.

When co-extrusion is performed using a feed block type T die, a multilayer foam sheet having an extremely beautiful appearance can be obtained by using the following T die. That is, when the width dimension of the inlet thickness direction cross section of the manifold connected to the resin flow path of the feed block in the T die is W, and the thickness dimension is T, the cross section is a square having W / T of 1 or more and 3 or less. It is a T-die that is shaped.

FIG. 1 shows an example of an apparatus for manufacturing a multilayer foam sheet in which a multi-manifold method and a feed block method are combined. FIG. 2 shows an AA cross section of FIG. First, after two types and three layers of a resin layer (1) / a foam layer (3) / a resin layer (2) are laminated in a layer by a feed block, a resin layer (4) and a resin layer (5) are further laminated. A multi-manifold system is used to laminate two types and three layers of (1) / foamed layer (3) / resin layer (2).

In the multi-manifold type T-die 1 shown in FIG. 1, when the width dimension of the cross section in the thickness direction of the inlet of the manifold 3 connected to the resin flow path of the feed block is W and the thickness dimension is T, W / T is 1 or more and 3 It is preferably 1 or more, more preferably 1 or more and 2 or less, further preferably 1 or more and 1.5 or less, and its cross-sectional shape is a square shape. As W / T is closer to 1, it is possible to produce a multi-layer foam sheet having a beautiful appearance without curtain defects.

Although the expansion ratio and thickness of the propylene-based resin multilayer foam sheet of the present invention are not particularly limited, they are suitable for high-magnification, thin-wall multilayer foam sheets. Usually, the expansion ratio of the entire sheet is 1.3 to 7 times, and the thickness of the entire sheet is 1 to 7 mm.

The surface of the multilayer foamed sheet made of a propylene-based resin of the present invention may be subjected to a surface treatment such as a corona treatment, an ozone treatment, or an antistatic agent application, if necessary. Further, a skin material such as a sheet or a film may be laminated on one or both sides of the propylene-based resin foam sheet of the present invention, depending on the application, to form a skin-material laminated propylene-based resin multilayer foam sheet. It is also possible to apply thermoforming such as vacuum forming to the propylene-based resin multilayer foam sheet and the skin material-laminated propylene-based resin multilayer foam sheet of the present invention.

As the skin material such as a sheet or film for lamination, a known material can be used depending on the use. For example, a metal sheet such as aluminum or iron, a thermoplastic resin, paper, a thin sheet made of synthetic paper, or the like can be used. No. A nonwoven fabric or woven fabric made of a thermoplastic material, a plant material such as hemp, or an inorganic material such as glass may be laminated. Further, decoration such as embossing or printing may be applied to the surface of the thin plate used. The foam may be laminated and bonded as a skin material.

For example, when the propylene-based resin multilayer foam sheet of the present invention is used for food packaging, it is preferable to laminate and use a propylene-based resin film or a gas barrier resin film having a thickness of 10 to 100 μm. As the gas barrier resin, an ethylene / vinyl alcohol copolymer, polyvinylidene chloride, polyvinyl alcohol, polyamide, or the like can be used. In addition, these gas barrier resins may be used alone or as a mixture, or two or more kinds of films made of the gas barrier resin may be laminated and used.

When the propylene-based resin multilayer foam sheet is used for an automobile interior material, it is preferable to laminate a nonwoven fabric, a woven fabric, a carpet, or the like. In addition, when used for packaging purposes, for example, as a partition plate for a box, a buffer sheet may be laminated to protect the contents.

The method of laminating the skin material on the propylene-based resin multilayer foam sheet is not particularly limited. For example, a method of applying an adhesive on the surface of the multilayer foam sheet and laminating the same, a skin material on which an adhesive resin film is laminated A method of heating and melting the surface of the adhesive resin film and laminating the foamed sheet, a method of melting and laminating the laminated surface of the skin material and the foamed sheet using a heater or hot air, etc., And a method of extruding and laminating between a foam sheet and a foam sheet.

The multilayer foamed sheet made of propylene-based resin of the present invention can be used for packaging, box passing, partition boards, food containers, stationery, building materials, automobile interior materials and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not impaired. The evaluation methods used in Examples and Comparative Examples are described below.

(1) Intrinsic viscosity of polymer Measurement was performed in tetralin at 135 ° C using an Ubbelohde viscometer. The intrinsic viscosity of the crystalline propylene polymer portion (B) was determined from the intrinsic viscosity and the weight of the crystalline propylene polymer portion (A) and the entire propylene-based polymer (T) using Equation 3 below.
[Η] _B = ([η] _T × 100− [η] _A × W _A ) ÷ W _B [Equation 3]
[Η] _T : intrinsic viscosity (dl / g) of propylene-based polymer (T)
[Η] _A : intrinsic viscosity (dl / g) of the crystalline propylene polymer portion (A)
W _A : Content (% by weight) of crystalline propylene polymer portion (A)
W _B: the content of the crystalline propylene polymer portion (B) (wt%)

(2) Molecular weight distribution P. C. (Gel permeation chromatography) was measured under the following conditions. The molecular weight distribution was evaluated by the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
Model: 150CV type (Millipore Waters)
Column: Shodex M / S 80
Measurement temperature: 145 ° C
Solvent: orthodichlorobenzene Sample concentration: 5mg / 8mL
A calibration curve was created using standard polystyrene. Mw / Mn of standard polystyrene (NBS706: Mw / Mn = 2.0) measured under these conditions was 1.9 to 2.0.

(3) Branching degree index [A]
The branching index [A] is defined by [η] Br / [η] Lin.
Here, [η] Br is the intrinsic viscosity of the polypropylene sample to be measured, and is [η] _T obtained by the measurement. [Η] Lin is the intrinsic viscosity of an isotactic semi-crystalline linear polypropylene having substantially the same weight average molecular weight Mw as that of the measurement sample, and propylene produced using a Ziegler-Natta catalyst. It was determined using the relational expression [η] Lin = 3.56 × 10 ⁻⁴ Mw ^0.67 in the system polymer.

(4) MFR
According to JIS K7210, it was measured at a temperature of 230 ° C. and a load of 2.16 kgf. The unit is g / 10 minutes.

(5) Melt tension (MT)
Using a melt tension tester MT-501D3 manufactured by Toyo Seiki Co., Ltd., a strand is extruded from an orifice having a length of 8 mm and a diameter of 2 mm at a sample amount of 5 g, a preheating temperature of 190 ° C., a preheating time of 5 minutes, and an extrusion speed of 5.7 mm / min. The tension when the strand was wound at a winding speed of 100 rpm using a roller having a diameter of 50 mm was measured as a melt tension (MT) (unit = g).

(6) Expansion Ratio The density ρ _T of the entire multilayer foam sheet was determined using a measurement method based on the underwater replacement method according to JIS K7112, and the overall expansion ratio was calculated by the following equation. The density ρ ₃ of the foamed layer (3) includes the overall density ρ _T and the thickness t _T , the density ρ ₁ and the thickness t _{1 of} the resin layer (1) (same as the resin layer (2)), and the resin layer (4) ( Using the density ρ ₄ and the thickness t ₄ of the resin layer (5), the expansion ratio of only the foam layer (3) was calculated from the following equation. Note that a value of 0.90 g / cm ³ was used for ρ ₀ in the following equation, and the thickness of each layer was measured using a normal optical microscope. The unit is ρ (g / cm ³ ) and t (cm).
・ Overall foaming ratio = ρ ₀ / ρ _T
· Foam layer (3) Density [rho ₃ = a _{(t T × ρ T -2 (} t 1 × ρ 1 + t 4 × ρ 4)) / (t T -2 (t 1 + t 4))
・ Expansion ratio of foam layer (3) = ρ ₀ / ρ ₃

(7) Surface resistivity In the width direction of the multilayer foamed sheet, sampling was performed at five locations with a size of 100 mm x 100 mm, and the surface resistivity of each sample was measured using a surface resistance measuring device (SME-8310 manufactured by Toa Denpa Kogyo Co., Ltd.). Measured at 50% relative humidity and 23 ° C. room temperature. The logarithmic average value at five locations in the width direction of the sample front and back was determined as a representative value.

[Reference Example 1] (Production of linear propylene resin PP1)
[1] (Synthesis of Ziegler-Natta solid catalyst component)
After replacing a 200-liter SUS reaction vessel equipped with a stirrer with nitrogen, 80 liters of hexane, 6.55 mol of tetrabutoxytitanium, 2.8 mol of diisobutyl phthalate, and 98.9 mol of tetraethoxysilane were charged, and a homogeneous solution was added. did. Next, 51 l of a solution of butylmagnesium chloride in diisobutyl ether having a concentration of 2.1 mol / l was gradually added dropwise over 5 hours while maintaining the temperature in the reaction vessel at 5 ° C. After completion of the dropwise addition, the mixture was further stirred at room temperature for 1 hour, and then washed with 70 liters of solid-liquid separator Ruen at room temperature three times.

  Next, toluene was added so that the slurry concentration became 0.6 kg / liter, then a mixed solution of 8.9 mol of n-butyl ether and 274 mol of titanium tetrachloride was added, and 20.8 mol of phthalic acid chloride was further added. The reaction was performed at 110 ° C. for 3 hours. After completion of the reaction, washing with toluene was performed twice at 95 ° C.

  Next, after adjusting the slurry concentration to 0.6 kg / liter, 3.13 mol of diisobutyl phthalate, 8.9 mol of n-butyl ether and 137 mol of titanium tetrachloride were added, and the mixture was reacted at 105 ° C. for 1 hour. After the completion of the reaction, the mixture was subjected to solid-liquid separation at the same temperature, followed by washing twice at 95 ° C. with 90 liters of toluene.

  Next, after adjusting the slurry concentration to 0.6 kg / liter, 8.9 mol of n-butyl ether and 137 mol of titanium tetrachloride were added, and the mixture was reacted at 95 ° C. for 1 hour. After completion of the reaction, solid-liquid separation was performed at the same temperature, and washing with 90 liters of toluene was performed three times at the same temperature.

  Next, after adjusting the slurry concentration to 0.6 kg / liter, 8.9 mol of n-butyl ether and 137 mol of titanium tetrachloride were added, and the mixture was reacted at 95 ° C. for 1 hour. After completion of the reaction, solid-liquid separation was carried out at the same temperature, washing was carried out three times with 90 liters of toluene at the same temperature, washing was further carried out three times with 90 liters of hexane, followed by drying under reduced pressure to obtain 11.0 kg of solid catalyst component. Obtained.

  The solid catalyst component contains 1.9% by weight of titanium atom, 20% by weight of magnesium atom, 8.6% by weight of phthalic acid ester, 0.05% by weight of ethoxy group, and 0.21% by weight of butoxy group. Particle properties.

[2] (Pre-activation of solid catalyst component)
1.5 L of n-hexane, 37.5 mmol of triethylaluminum, 3.75 mmol of t-butyl-n-propyldimethoxysilane, which was sufficiently dehydrated and degassed in a SUS autoclave having an internal volume of 3 liters and equipped with a stirrer, 15 g of the solid catalyst component obtained in [1] was added, and 15 g of propylene was continuously supplied over 30 minutes while preserving the temperature in the vessel at 5 to 15 ° C. to perform preactivation.

[3] (Polymerization of crystalline propylene polymer portion (A))
In a 300 liter polymerization vessel made of SUS, while supplying a liquid propylene at 57 kg / h so as to maintain a polymerization temperature of 60 ° C. and a polymerization pressure of 27 kg / cm ² G, 1.3 mmol / h of triethylaluminum / t, 1.13 mmol / h of -butyl-n-propyldimethoxysilane and 0.51 g / h of the preactivated solid catalyst component are continuously fed to carry out propylene polymerization in the substantial absence of hydrogen. 0 kg / h of polymer was obtained. At this time, the produced amount of the polymer was 3920 g per 1 g of the catalyst. As a result of sampling and analyzing a part thereof, the intrinsic viscosity was 7.7 dl / g. The obtained polymer was continuously transferred to the second tank as it was.

[4] (Polymerization of crystalline propylene polymer part (B))
In a fluidized bed reactor with a stirrer having an internal volume of 1 m ³ , while supplying propylene and hydrogen so as to maintain a polymerization temperature of 80 ° C., a polymerization pressure of 18 kg / cm ² G, and a hydrogen concentration of 8 vol% in the gas phase, the first tank was used. By continuously continuing propylene polymerization while supplying the catalyst-containing polymer transferred from the eye and 60 mmol / h of triethylaluminum and 6 mmol / h of t-butyl-n-propyldimethoxysilane, 18.2 kg / h was obtained. A polymer (T) was obtained. The intrinsic viscosity of this polymer was 1.9 dl / g.

  From the above results, the amount of polymer produced during the polymerization of (B) was 31760 g per 1 g of the catalyst, the polymerization weight ratio of the first tank and the second tank was 11:89, and the intrinsic viscosity of (B) was It was determined to be 1.2 dl / g.

[5] (Pelletization of polymer)
0.1 part by weight of calcium stearate, 0.05 part by weight of trade name Irganox 1010 (manufactured by Ciba Geigy), 100 parts by weight of polymer (T) powder, trade name: Sumilizer BHT (manufactured by Sumitomo Chemical Co., Ltd.) 2 parts by weight were added and mixed, and the mixture was melt-kneaded at 230 ° C., and pellets having a melt flow rate MFR of 12 g / 10 minutes, a molecular weight distribution of 8.0, and a weight average molecular weight Mw of 3.39 × 10 ⁵ (propylene resin) PP1) was obtained.
When the melt tension MT of this pellet was measured, it was 4.7 g, and 7.52 × MFR (230) ^{(−0.576) on} the right side of [Equation 1] was 1.80, which satisfied [Equation 1]. .

Furthermore, the branching degree index [A] of this pellet was determined as follows, and was 1.06, which was 0.90 or more.
[A] = [η] Br / [η] Lin
= [Η] _T /(3.56×10 ⁻⁴ Mw ^0.67 )
= 1.9 / 1.8 = 1.06
Here, 3.39 × 10 ⁵ was used as the weight average molecular weight Mw. Note that the branching degree index [A] is theoretically a value of 0 or more and 1.00 or less, and it is considered that the closer to 1.00, a linear polymer chain and the closer to 0, a branched polymer chain. . In the above description, [A] is 1.06, which slightly exceeds 1.00, but is within an error and is considered to be an extremely linear polymer chain.

[Example 1] (Extrusion foaming test)
A multilayer foam sheet made of a propylene-based resin having a layer structure of resin layer (4) / resin layer (1) / foam layer (3) / resin layer (2) / resin layer (5) was prepared by the method described below.

  A 104 mmφ co-rotating twin-screw extruder (L / D = 32, L is an effective screw length, D is a screw diameter) equipped with a gear pump at the tip as an extruder for the foamed layer (3), a resin layer (1) and A 90 mmφ single screw extruder (L / D = 32) was used as an extruder for the resin layer (2), a feed block was connected to these extruders, and the resin layer (1) / After obtaining a laminate of the foamed layer (3) / the resin layer (2), it was introduced into a multi-manifold type T die having an outlet channel width (Wd) of 1600 mm. The flow paths in the multi-manifold type T die and the feed block are shaped as shown in FIGS. 1 and 2, the width W of the manifold inlet is 30 mm, which is the same as the diameter of the manifold, and the height T is 30 mm. Was. Subsequently, the resin for the resin layer (4) and the resin for the resin layer (5) were added to the resin layer (1) / foamed layer (3) / resin layer (2) laminate expanded to the width Wd by a 75 mmφ single screw extruder. (L / D = 32) and were merged in a layered manner near the die exit.

50 parts by weight of the linear propylene-based resin PP1 (MFR = 12 g / 10 min) obtained in Reference Example 1 [5] above was polymerized using a Ziegler-Natta catalyst, and the linear propylene resin not satisfying the relationship of Formula 1 was obtained. 40 parts by weight of propylene-based resin PP2 (manufactured by Sumitomo Chemical Co., Ltd., Noblen AW191A (MFR = 11 g / 10 min, MT = 0.9 g, 1.89 on the right side of Formula 1)), linear low density polyethylene PE1 10 parts by weight of Sumikasen E, FV401 (MFR = 4 g / 10 min) manufactured by Sumitomo Chemical Co., Ltd. were blended.
A raw material resin obtained by blending 0.5 PHR of a foam nucleating agent (manufactured by Nippon Boehringer Ingelheim Co., Ltd., Hydrocelol CF40E) was charged into the extruder hopper for the foamed layer (3) via a quantitative feeder. The melt-kneading was performed, and 0.5 PHR of liquefied carbon dioxide gas was injected at a high pressure using a diaphragm type metering pump at a position where the melting was advanced (L / D = 20). After sufficiently melting and kneading the molten resin and carbon dioxide gas, the mixture was cooled and adjusted to 180 ° C., and was stably introduced into the feed block at a discharge rate of 160 kg / h using a gear pump.

On the other hand, as the resin for the resin layer (1) and the resin layer (2), 35 parts by weight of the linear propylene-based resin PP1, 35 parts by weight of the linear propylene-based resin PP2, and MF110 which is a master batch of the filler talc. A masterbatch containing 70 wt% of talc having an average particle size of 2.8 μm (manufactured by Sumitomo Chemical Co., Ltd., propylene resin as a base resin), and 30 parts by weight thereof were used. The added amount of talc itself was (30 × 70) / 100 = 21 parts by weight. The density ρ ₁ (ρ ₂ ) of these compounds is 1.04 g / cm ³ , and the mixture is put into an extruder hopper for the resin layer (1) and the resin layer (2) through a fixed-quantity feeder to perform melt kneading. It was cooled and adjusted to 200 ° C., and introduced into the feed block at a discharge rate of 25 kg / h.
Further, as a resin for the resin layer (4) and the resin layer (5), a linear propylene-based resin PP3 that is polymerized using a Ziegler-Natta catalyst and does not satisfy the relationship of Formula 1 (Noblen, manufactured by Sumitomo Chemical Co., Ltd.) 80 parts by weight of AS171G (MFR = 1 g / 10 min, MT = 5.0 g, 7.52 on the right side of Formula 1), and 20 parts of a polymer type antistatic agent (Pelestat 300, manufactured by Sanyo Chemical Industries, Ltd.). What was blended by weight was used. The density ρ ₄ (ρ ₅ ) of these compounds is 0.90 g / cm ³ , and the mixture is put into an extruder hopper for a resin layer (4) and a resin layer (5) via a fixed-quantity feeder to perform melt kneading. It was cooled and adjusted to 200 ° C., and introduced into a multi-manifold type T-die at a discharge rate of 15 kg / h.
The flat foamed sheet extruded from the T-die was cooled and formed by a large number of 210φ rolls, which were installed immediately after the T-die and adjusted to a temperature of about 60 ° C., and was taken up by a take-up machine equipped with a nip roll. The sheet was cut to a predetermined size to obtain a propylene-based resin multilayer foam sheet.

  The expansion ratio of the whole foamed sheet of the obtained multilayer foamed sheet made of a propylene-based resin was 3.3 times, and the thickness was 4.0 mm. The expansion ratio of only the foam layer (3) is 4.0 times, the thickness of the resin layer (1) and the thickness of the resin layer (2) are each 70 μm, and the thickness of the resin layer (4) and the resin layer (5) are each 50 μm. Met. The surface properties of the multi-layer foamed sheet made of a propylene-based resin were smooth, the appearance was poor due to outgassing, and the appearance was beautiful. The surface resistivity was 10 10 Ω / □.

[Example 2]
Example 1 was repeated except that the composition ratio of the resin for the resin layer (1) and the resin for the resin layer (2) was changed as follows.
As the resin for the resin layer (1) and the resin layer (2), 20 parts by weight of the linear propylene-based resin PP1 and 20 parts by weight of the linear propylene-based resin PP2, and MF110 (Sumitomo) which is a master batch of the filler talc A master batch containing 70 wt% of talc having an average particle size of 2.8 μm, manufactured by Chemical Industry Co., Ltd., and a mixture of 60 parts by weight of a base resin (propylene resin) were used. The added amount of talc itself was (60 × 70) / 100 = 42 parts by weight. The density ρ ₁ (ρ ₂ ) of these compounds is 1.23 g / cm ³ , and they are put into an extruder hopper for the resin layer (1) and the resin layer (2) via a quantitative feeder to perform melt kneading. It was cooled and adjusted to 200 ° C., and introduced into the feed block at a discharge rate of 25 kg / h.
The expansion ratio of the whole foamed sheet of the obtained multilayer foamed sheet made of a propylene-based resin was 3.3 times, and the thickness was 4.0 mm. The expansion ratio of the foam layer (3) was 4.0 times, the thickness of the resin layer (1) and the resin layer (2) was 60 μm, and the thickness of the resin layer (4) and the resin layer (5) was 50 μm. The surface properties of the multi-layer foamed sheet made of a propylene-based resin were smooth, the appearance was poor due to outgassing, and the appearance was beautiful. The surface resistivity was 10 10 Ω / □.

[Comparative Example 1]
Example 1 was carried out in the same manner as in Example 1 except that the compositions of the resins constituting the resin layer (1) and the resin layer (2) were changed as follows.
As the resin for the resin layer (1) and the resin layer (2), a resin in which 70 parts by weight of the linear propylene-based resin PP2 and 30 parts by weight of MF110 which is a master batch of the filler talc was used. The added amount of talc itself was (30 × 70) / 100 = 21 parts by weight. The density ρ ₁ (ρ ₂ ) of these compounds was 1.04 g / cm ³ , and the mixture was fed into a resin layer (1) and a resin layer (2) extruder hopper through a quantitative feeder and melt-kneaded. After cooling and adjusting to ° C., the mixture was introduced into the feed block at a discharge rate of 25 kg / h.
The expansion ratio of the whole foamed sheet of the obtained multilayer foamed sheet made of a propylene-based resin was 3.3 times, and the thickness was 4.0 mm. The expansion ratio of the foam layer (3) was 4.0 times, the thickness of the resin layer (1) and the resin layer (2) was 70 μm, and the thickness of the resin layer (4) and the resin layer (5) was 50 μm. On the surface of the multi-layer foamed sheet made of propylene-based resin, poor appearance was supposedly caused by outgassing. The surface resistivity was 10 10 Ω / □.

FIG. 1 is a drawing showing an example of a T-die combining a feed block and a multi-manifold system. FIG. 2 is a drawing showing an example of the AA plane of FIG.

Explanation of reference numerals

1: Multi-manifold type T die 2: Feed block 3: Manifold 4: Manifold 5: Manifold 6: Manifold 7: Manifold 8: Manifold

Claims (4)

In a propylene-based resin multilayer foam sheet having a resin layer (1) and a resin layer (2) on the surface of a propylene-based resin foam layer (3) obtained by co-extrusion using a T-die, foaming of the foam layer When the magnification is 2.5 times or more, the foamed layer (3), the resin layer (1) and the resin layer (2) have a melt tension (MT (190)) at 190 ° C. and a melt flow rate (MFR) at 230 ° C. (230)) contains at least 10% by weight of the linear propylene polymer (A) satisfying the following formula 1, and the resin layer (1) and the resin layer (2) contain the filler (A). A multi-layer foamed sheet made of propylene-based resin.
MT (190) ≧ 7.52 × MFR (230) ^(−0.576) [Equation 1] The propylene resin multilayer foam sheet according to claim 1, wherein the linear propylene polymer (A) contained in the foam layer (3), the resin layer (1) and the resin layer (2) has an intrinsic viscosity. An intrinsic viscosity obtained by a polymerization method including a step of producing a crystalline propylene polymer part (A) of 5 dl / g or more and a step of producing a crystalline propylene polymer part (B) having an intrinsic viscosity of less than 3 dl / g. Is less than 3 dl / g, and the proportion of the crystalline propylene polymer portion (A) is a linear propylene polymer having a proportion of 0.05% by weight or more and less than 35% by weight. The resin layer (4) / the resin layer (1) / the foam layer (3) / the resin layer (2) / the resin layer (5) are laminated in this order, and the resin layer (4) and the resin layer (5) are surface layers. The propylene-based resin multilayer foam sheet according to claim 1 or 2, wherein the resin layer (4) and / or the resin layer (5) contains a polymer type antistatic agent. A container made of the propylene-based resin multilayer foam sheet according to claim 1.

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