JP6897338B2 - Foaming laminate and foaming laminate - Google Patents

Description

The present invention relates to an effervescent laminate and an effervescent laminate that are highly productive and exhibit good heat insulating properties and an effervescent appearance.

Conventionally, synthetic resins, especially those in which polystyrene is foamed, are often used as containers having heat insulating properties. However, expanded polystyrene containers have drawbacks such as a high environmental load at the time of disposal and inferior printability, and alternatives to other materials are being considered. Under such circumstances, a container in which corrugated paper is bonded to the outer peripheral surface of the body of the paper cup to form a heat insulating layer, a container in which a laminate of pulp non-woven fabric and coated paper is bonded to the outer peripheral surface of the body of the paper cup, etc. Has been developed and used.

However, each method has a drawback that it is not easy to process and mold, and the cost is high. Therefore, a technique of laminating a low melting point thermoplastic synthetic resin film on at least one surface of a base material containing water and heating the base material to foam the synthetic resin film unevenly using the water contained in the base material. Was devised (see, for example, Patent Documents 1 to 3). However, in the material thus obtained, the thickness of the foam layer is thin and the heat insulating property is insufficient.

Further, it is composed of a container body member and a bottom plate member, and a high melting point thermoplastic synthetic resin film is laminated on the inner wall surface of the base paper of the container body member and the bottom plate member, and a low melting point heat is formed on the outer wall surface of the base paper of the container body member. A heat insulating paper container in which a plastic synthetic resin film is laminated and the thermoplastic synthetic resin film having a low melting point is heat-treated and foamed has been proposed (see, for example, Patent Document 4).

However, although the heat insulating paper container having a high melting point thermoplastic synthetic resin on the inner wall surface has good heat insulating properties, if the processing speed when laminating the low melting point thermoplastic resin is increased, the foamed appearance deteriorates and the production It was inferior in sex.

Further, as a heat insulating paper container having an excellent foamed appearance, a heat insulating paper container having a foamed layer in which low-density polyethylene having a specific melt mass flow rate is foamed on at least one side of the paper has been proposed (for example, Patent Documents 5 to 6). reference).

However, even if low-density polyethylene in which only the melt mass flow rate is controlled is used, the deterioration of the foamed appearance is not solved when the processing speed at the time of laminating molding is increased, and the productivity is inferior.

Further, as a heat insulating container having an excellent foamed appearance, a heat insulating container having a foamed layer of foamed high-pressure low-density polyethylene having a molecular weight of 100,000 or more and a ratio of 30.0% or less to the whole has been proposed (for example). , Patent Document 7).

However, even if low-density polyethylene having a reduced molecular weight of 100,000 or more is used, the deterioration of the foamed appearance is not solved when the processing speed at the time of laminating molding is increased, and the productivity is inferior.

Special Publication No. 48-322383 Japanese Unexamined Patent Publication No. 57-110439 Japanese Unexamined Patent Publication No. 2001-270571 Japanese Unexamined Patent Publication No. 2004-558534 Japanese Patent No. 5197983 JP 2015-171794 JP-A-2009-196200

An object of the present invention is to provide a foamed laminate and a foamed laminate that are highly productive and exhibit good heat insulating properties and a foamed appearance.

As a result of diligent studies to solve the above problems, the present inventors have found that a specific foam laminate and foam laminate are highly productive and exhibit excellent heat insulating properties and foam appearance. The invention was completed.

That is, the present invention relates to a laminate for foaming, which comprises at least a layer (A) / a paper base material layer, and the layer (A) is composed of a low-density polyethylene (a) satisfying the following (i) to (iii). It is a thing.

(I) The value of the ratio Mw / Mn of the number average molecular weight (Mn) to the weight average molecular weight (Mw) measured by the GPC method is 5.00 or more and 8.50 or less. (Ii) The integrated molecular weight distribution measured by the GPC method. In the curve, the proportion of components having a molecular weight of 1 million or more is 0.50% or more and 1.50% or less.

(Iii) The melting tension at 130 ° C. is 40 mN or more and 120 mN or less.

Further, the present invention relates to a foamed laminate characterized in that the layer (A) of the foamed laminate is foamed.

Hereinafter, the present invention will be described in detail.

The low-density polyethylene (a) constituting the layer (A) of the foaming laminate of the present invention is composed of the high-pressure method low-density polyethylene (c), the linear low-density polyethylene (d), or a composition thereof. High pressure method It is preferable that it is composed only of low density polyethylene (c).

The high-pressure method low-density polyethylene (c) can be obtained by a conventionally known high-pressure method radical polymerization method, and the above (i) to (iii) can be obtained by changing the polymerization temperature, its profile, the polymerization pressure, and the modifier. Can be controlled.

The linear low-density polyethylene (d) can be obtained by copolymerizing ethylene and α-olefin by a high-, medium- and low-pressure ion polymerization method using a Ziegler-Natta catalyst, a Phillips catalyst, and a metallocene catalyst.

Examples of the α-olefin used for the linear low-density polyethylene (d) include propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-pentene, 1-hexene and 1-hexene. , 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene and the like, and one or more of these may be used.

The density of low-density polyethylene (a) measured by JIS K6922-1 (1997) (hereinafter, simply abbreviated as density) is preferably in the range of ^{910 to 930 kg / m 3 because of its excellent heat insulating properties and foamed appearance.} It is more preferably in the range of 914 to 925 kg / m ³ , and even more preferably in the range of ^{916 to 920 kg / m 3.}

The melt mass flow rate (hereinafter, simply abbreviated as MFR) measured by JIS K6922-1 (1997) of low-density polyethylene (a) is preferably in the range of 7 to 30 g / 10 minutes, and has good heat insulating properties and foamed appearance. From its superiority, it is more preferably in the range of 8 to 24 g / 10 minutes, more preferably 10 to 18 g / 10 minutes, and most preferably 10 to 16 g / 10 minutes.

The value of the ratio Mw / Mn of the number average molecular weight (Mn) to the weight average molecular weight (Mw) measured by the gel permeation chromatography method (hereinafter simply abbreviated as GPC method) of the low density polyethylene (a) is excellent in foaming performance. Therefore, it is in the range of 5.00 to 8.50, more preferably in the range of 6.0 to 8.50. When the Mw / Mn of the low-density polyethylene (a) is less than 5.00, it is not preferable because it is inferior in laminating workability, and when it is more than 8.50, it is not preferable because it is inferior in foamed appearance.

Further, in the integrated molecular weight distribution curve measured by the GPC method, the proportion of the components having a molecular weight of 1 million or more contained in the low-density polyethylene (a) is in the range of 0.50 to 1.50% because of its excellent foaming performance. It is more preferably in the range of 0.70 to 1.20%. If the proportion of the component having a molecular weight of 1 million or more contained in the low-density polyethylene (a) is less than 0.50% or more than 1.50%, the foamed appearance is inferior, which is not preferable.

The measurement method of the GPC method in the present invention is as follows.

First, after weighing the high-pressure low-density polyethylene to be measured, 1,2,4-trichlorobenzene for HPLC (manufactured by Wako Pure Chemical Industries, Ltd.) and BHT (manufactured by Wako Pure Chemical Industries, Ltd.) as an antioxidant are used. ) Was added to a solvent to which 0.1% was added, and the solution was dissolved by shaking at 140 ° C. for 1 hour so that the sample concentration was 1 mg / 1 mL, and the solution was prepared as a sample solution.

HLC-8121GPC / HT manufactured by Tosoh Corporation equipped with a differential refractive index detector as a detector was used as a measuring device, and the measurement was carried out as follows. As a separation column _{, three TSKgel GMH HR-} H (20) HTs (manufactured by Tosoh Corporation, inner diameter 7.8 mm, length 30 cm) were connected and used. For the moving layer, use 1,2,4-trichlorobenzene for HPLC (manufactured by Wako Pure Chemical Industries, Ltd.) with 0.05% BHT (manufactured by Wako Pure Chemical Industries, Ltd.) added as an antioxidant. Then, it was moved in a separation column maintained at 140 ° C. at a flow rate of 1.0 mL / min. 0.3 mL of the sample solution was injected into this, and the sample components separated by the differential refractometer were detected. Using a fifth-order approximation curve created using standard polystyrene (manufactured by Toso Co., Ltd., the molecular weight is the PE-equivalent molecular weight using the Q factor) as the calibration line, the integrated molecular weight distribution curve, the differential molecular weight distribution curve, and the number The average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated.

Regarding the analysis method of such GPC method, the technical report No. 1 published by Tosoh Analysis Center Co., Ltd. It is described in T1001 "GPC method (SEC method) introductory course" (created on October 1, 2013).

The melt tension of the low-density polyethylene (a) measured at a temperature of 130 ° C. and a take-up speed of 10 m / min (hereinafter, simply abbreviated as MS) is in the range of 40 to 120 mN, more preferably 50 to 120 mN because of its excellent foaming performance. It is in the range of 100 mN, most preferably 60 to 90 mN. If the MS of the polyethylene resin for extrusion lamination is less than 40 mN, it is not preferable because it is inferior in laminating workability, and if it exceeds 120 mN, it is not preferable because it is inferior in foamed appearance.

The MS in the present invention has an extrusion speed of 10 m / m under the condition that a capillary viscometer having a barrel diameter of 9.55 mm is equipped with a die having a length of 8 mm, a diameter of 2.095 mm and an inflow angle of 90 °, and a heat insulating chamber. It is a value measured at a set temperature of 130 ° C. and a take-up speed of 10 m / min.

The low-density polyethylene (a) constituting the layer (A) of the foaming laminate of the present invention may be blended with other polyolefins such as an ethylene / α-olefin copolymer.

When the polyolefin is mixed with the low-density polyethylene (a), it may be a pellet mixture in which the pellets of the low-density polyethylene (a) and the pellets of the polyolefin are mixed in a solid state, but a single-screw extruder or a twin-screw extruder may be used. , A mixture melt-kneaded with a kneader, a polyolefin, or the like is preferable because a product with stable quality can be obtained. When a melt-kneading device is used, the melting temperature is preferably about 300 ° C., which is the melting point of the polyolefin resin.

Further, for the low-density polyethylene (a), if necessary, an additive generally used for polyolefin resins such as an antioxidant, a light stabilizer, an antistatic agent, a lubricant, and an antiblocking agent is used as an object of the present invention. However, it is preferable not to add an antioxidant or a peroxide because the foaming performance is excellent.

The foaming laminate of the present invention becomes a foamed laminate by foaming the layer (A).

The thickness of the layer (A) before foaming, which constitutes the foamed laminate of the present invention, is not particularly limited as long as the object of the present invention is achieved, but is in the range of 60 to 150 μm because of its excellent foaming appearance. It is preferably, more preferably 80 to 120 μm, and even more preferably 80 to 100 μm.

The thickness of the layer (A) constituting the foamed laminate of the present invention is preferably 800 μm or more, more preferably 900 μm or more, and most preferably 1000 μm or more because of its excellent heat insulating properties.

The paper base material constituting the foaming laminate of the present invention is not particularly limited, but the basis weight of the paper base material is 150 to 400 g / m because the foaming ratio of the low-density polyethylene (a) can be improved. ² is preferable, and more preferably 250 to 350 g / m ² .

The water content of such a paper base material is not particularly limited, but is preferably ^{15 to 30 g / m 2} and more preferably 20 to 30 g / m 2 because the foaming ratio of the low density polyethylene (a) is improved. 30 g / ^{m 2,} and most preferably 20~26g / ^{m 2.}

As a method for obtaining the foamed laminate of the present invention, a method of extrusion laminating low density polyethylene (a) is exemplified.

As a method for obtaining a laminate by an extrusion laminating molding method, various extrusion laminating processing methods such as a single laminating processing method, a tandem laminating processing method, a sandwich laminating processing method, and a coextrusion laminating processing method can be exemplified. The temperature of the resin in the extrusion laminating method is preferably in the range of 240 to 350 ° C., and the surface temperature of the cooling roll is preferably in the range of 10 to 50 ° C.

In particular, the resin temperature directly under the T-die when the low-density polyethylene (a) is extruded and laminated is preferably in the range of 240 to 310 ° C., more preferably 250 to 300 ° C., and most preferably 250 to 300 ° C., because it has an excellent foamed appearance. It is in the range of 260 to 290 ° C.

Further, in the extrusion laminating molding method, the processing speed when forming the layer (A) made of low-density polyethylene (a) is preferably in the range of 50 to 200 m / min because it is excellent in foamed appearance and productivity. It is preferably 70 to 150 m / min, most preferably 80 to 130 m / min.

In such an extrusion laminating process, immediately after forming the polyethylene resin into an extruded layer in a molten state, the base material adhesive surface of the layer is exposed to an oxygen-containing gas or an ozone-containing gas, and the method of bonding to the base material is used. It is preferable because it has excellent adhesion to the base material layer. When improving the adhesiveness between the thermoplastic resin and the base material with ozone-containing gas, the amount of ozone gas to be treated is 0.5 mg or more of ozone per ^{1 m 2 of the film made of the thermoplastic resin extruded from the die.} It is preferable to spray.

In the extrusion lamination processing method in the method for obtaining the laminate of the present invention, in order to further improve the adhesiveness between the thermoplastic resin layer and the base material layer, the temperature at which the polyethylene-based resin does not foam, for example, 3 to 60 ° C. It can be heat-treated at temperature for 10 hours or more. Further, if necessary, a known surface treatment such as a corona treatment, a frame treatment, or a plasma treatment may be applied to the adhesive surface of the paper base material. Further, if necessary, an anchor coating agent may be applied to the paper substrate.

As a method for obtaining the foamed laminate of the present invention, water is applied to the paper substrate before laminating the low-density polyethylene (a) on the paper substrate layer in order to improve the heat insulating property and economy of the foamed laminate. You may.

The method of applying water is not particularly limited as long as the object of the present invention is achieved, and a method using a roll coating device, a lip coating device, a spray device, a die coating device, a gravure device, a dampening device, or the like is exemplified. be able to. Since the amount of water applied becomes uniform, a method using a dampening device is preferable.

For such dumping equipment, for example, the product name "High Rotor S" from Suzuki Sangyo Co., Ltd., the product name "WEKO Rotor Dumping" from Nikka Co., Ltd., and the product name "Toki Electronics Co., Ltd." "TSD-3000" is on sale.

The amount of water applied in the present invention is not particularly limited as long as the object of the present invention is achieved, but the foaming ratio of the low-density polyethylene (a) can be increased, and the paper substrate and the low-density polyethylene (a) can be applied. ^{1.5 to 30 g / m 2} is preferable, and 3 to 15 g / m ² is more preferable, because the adhesive strength with the material does not decrease.

By heating the foaming laminate of the present invention, a foamed laminate in which the layer (A) is foamed can be obtained.

As a heating method in the method for obtaining the foamed laminate of the present invention by heating foaming, in addition to hot air, electric heat, and electron beam, the laminate is formed into a container shape, and a high-temperature object is filled therein to utilize the heat of the filling material. Any means can be used. The heating can be performed by a method of performing batch-type in an oven, a method of continuously performing by a conveyor or the like, or the like.

The heat source for heating is not particularly limited as long as this object is achieved, and hot air, electric heat, electron beams, etc. can be exemplified for the laminated body and the molded container, and a high temperature object is internally filled in the laminated body and the molded container. Then, the heat of the filling material can be used as an example. Further, the heating method can be performed by a method of performing batch-type in an oven, a method of continuously performing by a conveyor or the like, or the like.

Conditions such as heating temperature and heating time are not particularly limited as long as the object of the present invention is achieved, and in general, when hot air is used as a heat source, the heating temperature is 150, which is equal to or higher than the melting point of the low-density polyethylene (a). Below ° C, the air volume is 0.5 to 2.0 ^{m 3} / hour, and the heating time is 10 seconds to 6 minutes.

The foaming laminate of the present invention is characterized by containing at least the (A) layer / paper base material, and is not only composed of only two components of the (A) layer and the paper base material, but also other components. For example, the layer (B) and the layer (C) may be included. Specifically, (A) layer / paper base material / (B) layer, (A) layer / paper base material / (B) layer / (A) layer, (B) layer / paper base material / (A) Layer / (B) layer, (A) layer / paper base material / (B) layer / (B) layer, (A) layer / (A) layer / paper base material / (B) layer, (A) layer / Paper base material / (B) layer / (C) layer, (B) layer / Paper base material / (A) layer / (C) layer, (C) layer / (B) layer / Paper base material / (A) Layer / (B) layer / (C) layer, (A) layer / paper base material / (B) layer / (C) layer / (B) layer / (A) layer, (B) layer / paper base material / Examples include (A) layer / (C) layer / (A) layer / (B) layer. The symbol / between the layers indicates that they are adjacent layers.

Examples of the layer (B) and the layer (C) include layers formed from synthetic polymer polymers, woven fabrics, non-woven fabrics, metal foils, papers, cellophane and the like. For example, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6 and nylon 66, high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-ethyl acrylate copolymer, ethylene- Methacrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyethylene resin such as ionomer, polypropylene resin, polybutene, acrylic resin, polyvinyl alcohol, polymethylpentene, polyvinyl chloride, Examples thereof include layers formed from synthetic polymer polymers such as polyvinyl chloride, polystyrene, polycarbonate, polyurethane, and cellulose-based resins. Further, these polymer polymer films and sheets may be further subjected to aluminum vapor deposition, alumina vapor deposition, silicon dioxide vapor deposition, or acrylic treatment. Further, these polymer polymer films and sheets may be further printed using urethane-based ink or the like. Examples of the metal foil include aluminum foil and copper foil, and examples of papers include kraft paper, high-quality paper, stretched paper, glassin paper, and paperboard such as cup base paper and printing paper base paper.

Among these, since the layer (B) has excellent heat insulating properties, the layer (B) is made of polyethylene-based resin (b), polypropylene-based resin, polyester-based resin, polyamide-based resin, and aluminum-deposited or alumina-deposited on these polymer polymer films. A film or metal foil on which silicon dioxide is vapor-deposited is preferable, and a polyethylene-based resin (b) is more preferable.

The density of such polyethylene resin (b) is thermal insulation, due to excellent stability of the foam, preferably in the range of 930~970kg / ^{m 3,} more preferably from 935~970kg / ^{m 3,} Most preferably, it is in the range of ^{945 to 965 kg / m 3.}

The polyethylene-based resin (b) is an ethylene homopolymer, an ethylene / α-olefin copolymer, or a composition thereof, and the form of the molecular chain thereof may be linear or may have branches. .. Such a polyethylene-based resin (b) is not particularly limited, and may not be out of the density range.

Examples of the ethylene homopolymer include medium- and low-pressure ethylene homopolymers and high-pressure low-density polyethylene. Medium / Low Pressure Method Ethylene homopolymers can be obtained by conventionally known medium / low pressure ion polymerization methods. Further, the high-pressure method low-density polyethylene can be obtained by a conventionally known high-pressure radical polymerization method.

Examples of the α-olefin used in the ethylene / α-olefin copolymer include propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-pentene, 1-hexene and 1-hexene. Examples thereof include 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, and one or more of these are used.

The method for obtaining the ethylene / α-olefin copolymer is not particularly limited, and high / medium / low pressure ion polymerization methods using a Ziegler-Natta catalyst, a Philips catalyst, a metallocene catalyst and the like can be exemplified. Such a copolymer can be conveniently selected from commercially available products.

Among these, since it is excellent in laminate moldability, it is measured at 10 to 90 parts by weight of medium / high density polyethylene (e) ^{having a density of 930 to 980 kg / m 3 and MFR at 1 to 20 g / 10 minutes at 235 ° C.} Ethylene resin compositions (g) ((e) and (f) containing 90 to 10 parts by weight of high-density low-density polyethylene (f) having a swell ratio (hereinafter simply abbreviated as SR) of 1.50 to 2.20. ) Is preferably 100 parts by weight).

The medium / high density polyethylene is an ethylene copolymer obtained by a conventionally known medium / low pressure ion polymerization method, ethylene obtained by a high / medium / low pressure ion polymerization method using a Ziegler-Natta catalyst, a Phillips catalyst, a metallocene catalyst, or the like. -Α-olefin copolymer is exemplified.

Further, in the medium / high density polyethylene (e), the ethylene resin composition (g) is excellent in laminating workability, so the MFR is preferably in the range of 6 to 100 g / 10 minutes, more preferably 8 to 60 g / 10. It is a range of minutes.

Further, the density of the medium / high density polyethylene (e) is preferably 930 to 980 kg / m ^{3 and} more ^{preferably 945 to 975 kg / m 3} because the ethylene resin composition (g) is excellent in laminating workability and productivity. preferable.

The MFR of the high-pressure method low-density polyethylene (f) is preferably 0.1 to 20 g / 10 minutes, preferably in the range of 0.3 to 10 g / 10 minutes, because the ethylene resin composition (g) is excellent in extrusion laminating processability. Is more preferable, and most preferably the range is 1 to 4 g / 10 minutes.

Further, in the high-pressure method low-density polyethylene (f), the density is preferably in the range of ^{910 to 935 kg / m 3 because the ethylene-based resin composition (g) is excellent in film-forming stability.}

Further, the SR of the high-pressure method low-density polyethylene (f) is preferably 1.50 to 2.20, preferably 1.75 to 2.20, because the ethylene-based resin composition (g) is excellent in film formation stability. The range is more preferred, most preferably the range of 1.90 to 2.20.

This SR uses the melt indexer used in JIS K6922-1 (1997), extrudes the resin filled in the device from the orifice under the conditions of a temperature of 235 ° C and an extrusion rate of 3 g / min, and is installed directly under the orifice. It is obtained by collecting a strand-shaped extrude with a measuring cylinder containing the above isopropanol and _{dividing the strand diameter (D) by the orifice diameter (D 0} ) of the melt indexer.

The MFR of the ethylene resin composition (g) is preferably in the range of 1 to 50 g / 10 minutes, more preferably in the range of 3 to 20 g / 10 minutes, because it is excellent in laminate moldability.

Further, the polyethylene-based resin (b) constituting the present invention may be blended with other polyolefins such as polypropylene, and the blending ratio of these polyolefins is 1 to 30% by weight in terms of laminate moldability and appearance of the laminate. It is preferable from the point of view.

When the polyolefin is mixed with such a polyethylene resin (b), it may be a pellet mixture in which the pellets of the polyethylene resin (b) and the pellets of the polyolefin are mixed in a solid state. A mixture melt-kneaded with a shaft extruder, kneader, Banbury or the like is preferable because a product with stable quality can be obtained. When a melt kneading device is used, the melting temperature is preferably about 300 ° C., which is the melting point of the polyethylene resin.

Further, as the polyethylene resin (b), if necessary, an additive generally used for a polyolefin resin such as an antioxidant, a light stabilizer, an antistatic agent, a lubricant, and an antiblocking agent is used as an object of the present invention. May be added as long as the above is not impaired.

The method for forming the layer (B) is not particularly limited, and various laminating methods such as an extrusion laminating method, a dry laminating method, a thermal laminating method, and a wet laminating processing method can be exemplified.

The thickness of such a layer (B) is not particularly limited as long as the object of the present invention is achieved, but it may have a thickness of 20 to 100 μm because it is excellent in foamability and has few problems such as breakage. Preferably, from the viewpoint of economy, the range of 20 to 50 μm is most preferable.

The foam laminate of the present invention is used at least as a heat insulating paper container used for a body member.

The foamed laminate of the present invention is a foamed laminate that is highly productive and exhibits good heat insulating properties and a foamed appearance when foamed.

It is a figure which shows the foam cell shape which the foam appearance is good. It is a figure which shows the foam cell shape which has a poor foam appearance.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
(1) Density Density was measured according to JIS K6922-1 (1997).
(2) Melt mass flow rate (MFR)
MFR was measured according to JIS K6922-1 (1997).
(3) Measurement of Integrated Molecular Weight Distribution Curve, Number Average Molecular Weight (Mn) and Weight Average Molecular Weight (Mw) by GPC Method Integrated Molecular Weight Distribution Curve of Low Density Polyethylene, Mn, Mw by the method described in the detailed description of the present invention. Was measured, and the value of Mw / Mn was calculated. Further, from the integrated molecular weight distribution curve obtained by this method, the ratio of 100,000 or more components contained in the low-density polyethylene and the ratio of the components having a molecular weight of 1 million or more were calculated.
(4) Melt tension (MS)
A capillary viscometer with a barrel diameter of 9.55 mm equipped with a die and a heat insulating chamber having a length of 8 mm, a diameter of 2.095 mm, and an inflow angle of 90 ° in a thermostatic chamber set at 23 ° C. (Toyo Seiki Seisakusho, trade name: Capillograph) is filled with 18 g of polyethylene resin, the piston descent speed is set to 10 mm / min, the take-up speed is set to 10 m / min, and the load (mN) required for take-back is set to the melt tension (MS). ).
(5) Heat Foaming A gear aging tester (No. 102-SHF-77 manufactured by Yasuda Seiki Seisakusho Co., Ltd.) obtained by cutting a laminate obtained in the Example into a size of 10 cm × 20 cm and molding it into a cylindrical shape and heating it to a predetermined temperature. After allowing it to stand for a predetermined time while applying hot air inside, it was taken out and cooled to room temperature in the air.
(6) Moisture content of paper base material The paper base material before laminating the polyethylene resin was measured using a Karl Fischer method moisture measuring device (manufactured by Mitsubishi Chemical Corporation, trade name CA-05). The measurement temperature is 165 ° C.
(7) Foam layer thickness A foam formed at a processing speed of 80 m / min obtained in Examples and a laminated laminate before foaming as a blank were sampled, and a cross-sectional photograph was taken with an optical microscope. The thickness of the foam layer was measured from the cross-sectional photograph and measured at 5 points.
(8) State of foamed surface The smoothness of the surface of the foam molded at the obtained processing speed of 80 m / min was visually observed. The case where the surface smoothness was good was evaluated as ⊚, the case where the surface smoothness was slightly good was evaluated as ◯, the case where the surface smoothness was good but slightly inferior was evaluated as Δ, and the case where the surface was poor was evaluated as ×.
(9) Maximum processing speed After peeling the high-density polyethylene (B) from the obtained foam, methylene blue (manufactured by Kishida Chemical Co., Ltd., first grade) is diluted to 0.1% by weight of methanol (Kishida Chemical Co., Ltd.). The paper substrate was dyed with a methylene blue solution diluted with (1st grade) manufactured by Co., Ltd. The surface of the foamed layer of this stained sample was observed at a magnification of 25 times using a digital camera (COOLPIX 995 manufactured by Nikon Corporation) mounted on a stereomicroscope (SMZ-2T manufactured by Nikon Corporation). When a fine and uniform foam cell as shown in FIG. 1 can be observed, the foam appearance is good, and when a large and non-uniform foam cell as shown in FIG. 2 can be observed, the foam appearance is poor, and a good foam appearance is obtained. The machining speed that could be maintained was defined as the maximum machining speed (m / min). It was evaluated as good when the maximum processing speed was 80 m / min or more.

Example 1
As the resin of the layer (A), MFR is 12 g / 10 minutes, density is 922 kg / m ³ , Mw / Mn is 7.43, the ratio of molecular weight of 100,000 or more is 30.6%, and the ratio of molecular weight of 1 million or more is 1. High-density polyethylene with .17% and MS of 118 mN (manufactured by Toso Co., Ltd., A1) is used as the resin for layer (B), with an MFR of 7 g / 10 minutes and a density of 940 kg / m ^3. Polyethylene (trade name Petrosen LW04-1 manufactured by Toso Co., Ltd.) (B1) was used.

First, (A1) is supplied to a single-screw extrusion laminator (manufactured by Musashinokikai Co., Ltd.) having a screw having a diameter of 90 mmφ, and extruded from the T-die so that the resin temperature directly under the T-die becomes 305 ° C., and the water content is 25. On a paper substrate having a basis weight of 6 / m ² and a basis weight of 320 g / m ² , a predetermined take-up speed (60 to 110 m / min, every 5 m / min), an air gap length of 130 mm, and a thickness of 70 μm. Extrusion laminate molding was performed. Further, (B1) is supplied to a single-screw extruder (manufactured by Musashinokikai Co., Ltd.) having a screw having a diameter of 90 mmφ, and at a temperature of 320 ° C., a take-up speed of 80 m / min, and an air gap length of 130 mm, (B1). Was extruded to a thickness of 40 μm to obtain a laminate obtained by laminating low-density polyethylene (A1) by the high-pressure method, a paper substrate, and high-density polyethylene (B1) in this order. The obtained laminate was heated at 120 ° C. for 5 minutes and foamed to obtain a foamed laminate. For the obtained foamed laminate, the thickness of the foamed layer, the state of the foamed surface, and the maximum processing speed were evaluated. The evaluation results are shown in Table 1.

Example 2
As the resin of the layer (A), MFR is 14 g / 10 minutes, density is 918 kg / m ³ , Mw / Mn is 7.94, the ratio of molecular weight of 100,000 or more is 32.3%, and the ratio of molecular weight of 1 million or more is 1. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A2) having an MS of .16% and an MS of 93 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 1.

Example 3
As the resin of the layer (A), MFR is 14 g / 10 minutes, density is 918 kg / m ³ , Mw / Mn is 6.76, the ratio of molecular weight of 100,000 or more is 29.9%, and the ratio of molecular weight of 1 million or more is 0. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A3) having an MS of .81% and an MS of 82 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 1.

Example 4
As the resin of the layer (A), MFR is 24 g / 10 minutes, density is 918 kg / m ³ , Mw / Mn is 8.13, the ratio of molecular weight of 100,000 or more is 33.2%, and the ratio of molecular weight of 1 million or more is 0. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A4) having an MS of .80% and an MS of 63 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 1.

Example 5
As resin (A) layer, the high-pressure low-density polyethylene (manufactured by Tosoh Corporation, A2) 90 parts by weight, MFR is 12 g / 10 min, an ethylene-1-hexene copolymer density is 905 kg / ^{m 3} (Toso Co., Ltd. trade name Niporon-Z HM510R) was blended to 10 parts by weight and melt-kneaded with a single-screw extruder (Placo Co., Ltd. caliber 50 mm) polyethylene-based resin composition (A5, MFR). 14 g / 10 minutes, density 916 kg / m ³ , Mw / Mn of 7.98, molecular weight of 100,000 or more was 30.3%, molecular weight of 1 million or more was 1.04%, MS was 85 mN). A foamed laminate was obtained by the same method as in Example 1 except for the above. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 1.

Example 6
As the resin of the layer (A), MFR is 24 g / 10 minutes, density is 918 kg / m ³ , Mw / Mn is 8.13, the ratio of molecular weight of 100,000 or more is 33.2%, and the ratio of molecular weight of 1 million or more is 0. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A6) having an MS of .80% and an MS of 63 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 1.

Comparative Example 1
As the resin of the layer (A), MFR is 14 g / 10 minutes, density is 917 kg / m ³ , Mw / Mn is 8.40, the ratio of molecular weight of 100,000 or more is 37.6%, and the ratio of molecular weight of 1 million or more is 1. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A7) having an MS of .92% and an MS of 94 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 2. It was inferior in foam appearance and maximum processing speed.

Comparative Example 2
As the resin of the layer (A), MFR is 23 g / 10 minutes, density is 924 kg / m ³ , Mw / Mn is 6.37, the ratio of molecular weight of 100,000 or more is 26.1%, and the ratio of molecular weight of 1 million or more is 0. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A8) having a weight of .30% and an MS of 40 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 2. When the layer (A) was formed, the thickness of the laminate was not stable, and the foamed laminate could not be evaluated.

Comparative Example 3
As the resin of the layer (A), MFR is 8 g / 10 minutes, density is 920 kg / m ³ , Mw / Mn is 6.76, the ratio of molecular weight of 100,000 or more is 28.9%, and the ratio of molecular weight of 1 million or more is 2. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A9) having a molecular weight of .00% and an MS of 160 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 2. It was inferior in foam appearance and maximum processing speed.

Comparative Example 4
As the resin of the layer (A), MFR is 8 g / 10 minutes, density is 922 kg / m ³ , Mw / Mn is 6.58, the ratio of molecular weight of 100,000 or more is 30.0%, and the ratio of molecular weight of 1 million or more is 0. A foamed laminate was obtained by the same method as in Example 1 except that a high-pressure low-density polyethylene (manufactured by Toso Co., Ltd., A10) having an MS of .75% and an MS of 135 mN was used. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 2. It was inferior in foam appearance and maximum processing speed.

Comparative Example 5
As the resin of the layer (A), 50 parts by weight of high-pressure low-density polyethylene (manufactured by Tosoh Co., Ltd., A4), MFR 14 g / 10 minutes, density 917 kg / m ³ , MS 117 mN, high-pressure low density. A polyethylene-based resin composition (A11, MFR 18 g / 10 minutes) in which polyethylene (manufactured by Tosoh Co., Ltd.) is blended to 50 parts by weight and melt-kneaded with a single-screw extruder (manufactured by Placo Co., Ltd., diameter 50 mm) Examples except that a density of 918 kg / m ³ , Mw / Mn of 8.55, a molecular weight of 100,000 or more was 34.5%, a molecular weight of 1 million or more was 1.27%, and MS was 95 mN). A foamed laminate was obtained by the same method as in 1. The foamed layer thickness, foamed appearance and maximum processing speed of the obtained foamed laminate were evaluated. The evaluation results are shown in Table 2. It was inferior in foam appearance and maximum processing speed.

The foaming laminate of the present invention is suitably used for containers that require heat insulation, such as paper containers for high-temperature beverages such as coffee and soup, and containers for instant foods such as instant noodles.

Claims (4)

A foaming laminate comprising at least a layer (A) / a paper substrate layer, and the layer (A) is composed of a low-density polyethylene (a) satisfying the following (i) to (iv).
(I) The value of the ratio Mw / Mn of the number average molecular weight (Mn) to the weight average molecular weight (Mw) measured by the GPC method is 5.00 or more and 8.50 or less. (Ii) The integrated molecular weight distribution measured by the GPC method. In the curve, the proportion of components having a molecular weight of 1 million or more is 0.50% or more and 1.50% or less.
(Iii) The MS at 130 ° C. is 40 mN or more and 120 mN or less.
(Iv) High pressure method Consists of only low density polyethylene (c). The foaming laminate according to claim 1, wherein the low-density polyethylene (a) has an MFR of 7 g / 10 minutes or more and 30 g / 10 minutes or less. A foamed laminate according to claim 1 or 2 , wherein the layer (A) of the foamed laminate is foamed. A heat insulating paper container characterized in that the foamed laminate according to claim 3 is used at least for a body member.

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