JP2018094906A - Laminated body for foaming and foam laminated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated body for foaming high in productivity and also showing excellent adiabaticity and foam appearance.SOLUTION: Provided is a laminated body for foaming at least comprising an (A) layer/a paper base material layer, in which the (A) layer is composed of low density polyethylene (a) satisfying the following (i) to (iii): (i) where the value of a ratio Mw/Mn between the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured by a GPC method is 5.00 to 8.50; (ii) where, in an integrated molecular weight distribution curve measured by the GPC method, the ratio of the components with a molecular weight of 1,000,000 is 0.50 to 1.50; and (iii) where fusion tension at 130°C is 40 to 120 mN.SELECTED DRAWING: None

Description

  The present invention relates to a foamed laminate and a foamed laminate having high productivity and good heat insulation and foam appearance.

  Conventionally, as a container having a heat insulating property, a synthetic resin, in particular, a polystyrene foamed one is often used. However, the expanded polystyrene container has drawbacks such as high environmental load at the time of disposal and poor printability, and alternatives to other materials are being studied. Under such circumstances, a container in which corrugated paper is pasted on the outer peripheral surface of the paper cup body to form a heat insulating layer, a container in which a laminate of pulp nonwoven fabric and coated paper is bonded to the outer peripheral surface 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, by laminating and heating a low-melting-point thermoplastic synthetic resin film on at least one surface of the moisture-containing base material, the synthetic resin film is foamed into irregularities using the moisture contained in the base material. Has been devised (see, for example, Patent Documents 1 to 3). However, the material thus obtained has a thin foam layer and insufficient heat insulation.

  The container body member and the bottom plate member are composed of a high-melting point thermoplastic synthetic resin film laminated on the inner wall surface of the base material of the container body member and the bottom plate member, and the low melting point heat is applied to the outer wall surface of the base material of the container body member. There has been proposed a heat-insulating paper container in which a plastic synthetic resin film is laminated and the low-melting thermoplastic synthetic resin film is foamed by heat treatment (see, for example, Patent Document 4).

  However, heat insulating paper containers with high melting point thermoplastic synthetic resin on the inner wall surface have good heat insulation, but if the processing speed when laminating low melting point thermoplastic resin is increased, the foam appearance deteriorates and production It was inferior.

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

  However, even if low-density polyethylene with only the melt mass flow rate controlled is used, when the processing speed at the time of laminate molding is increased, the deterioration of the foam appearance is not eliminated and the productivity is poor.

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

  However, even if low-density polyethylene with a component having a molecular weight of 100,000 or more is used, deterioration of the foam appearance is not eliminated when the processing speed at the time of laminate molding is increased, resulting in poor productivity.

Japanese Patent Publication No. 48-32283 JP-A-57-110439 JP 2001-270571 A JP 2004-58534 A Japanese Patent No. 5197983 Japanese Patent Laying-Open No. 2015-171794 JP 2009-196200 A

  An object of the present invention is to provide a foamed laminate and a foamed laminate that have high productivity and exhibit good heat insulation and foam appearance.

  As a result of intensive 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 insulation and foam appearance. The invention has been completed.

  That is, the present invention relates to a foam laminate comprising at least (A) layer / paper base material layer, wherein (A) layer is composed of low density polyethylene (a) satisfying the following (i) to (iii): Is.

(I) The value of the ratio Mw / Mn of the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured by GPC method is 5.00 or more and 8.50 or less (ii) Integrated molecular weight distribution measured by GPC method In the curve, the proportion of components having a molecular weight of 1,000,000 or more is 0.50% or more and 1.50% or less.

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

  Further, the present invention relates to a foam laminate, wherein the layer (A) of the foam laminate is foamed.

  Hereinafter, the present invention will be described in detail.

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

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

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

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

The density (hereinafter simply abbreviated as density) measured by JIS K6922-1 (1997) of low-density polyethylene (a) is excellent in heat insulation and foam appearance, and is preferably in the range of 910 to 930 kg / m ³ . more preferably 914~925kg / ^{m 3,} still more preferably from 916~920kg / ^{m 3.}

  Also, 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 min. Since it is excellent, it is more preferably in the range of 8 to 24 g / 10 minutes, further preferably 10 to 18 g / 10 minutes, and most preferably 10 to 16 g / 10 minutes.

  The ratio Mw / Mn of the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured by gel permeation chromatography (hereinafter simply referred to as GPC method) of 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 6.00 to 8.50. If the Mw / Mn of the low density polyethylene (a) is less than 5.00, the laminate processability is inferior, and it is not preferable, and if it exceeds 8.50, the foamed appearance is inferior.

  Further, in the integral molecular weight distribution curve measured by the GPC method, the proportion of the component having a molecular weight of 1,000,000 or more contained in the low density polyethylene (a) is excellent in foaming performance, so that it is in the range of 0.50 to 1.50%. More preferably, it is 0.70 to 1.20% of range. 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.

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

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

Using Tosoh Corporation HLC-8121GPC / HT equipped with a differential refractive index detector as a detector, the measurement was performed as follows. As a separation column, three TSKgel GMH _HR- H (20) HT (manufactured by Tosoh Corporation, inner diameter 7.8 mm, length 30 cm) were connected and used. For the moving layer, use is made by adding 0.05% BHT (manufactured by Wako Pure Chemical Industries, Ltd.) as an antioxidant to 1,2,4-trichlorobenzene for HPLC (manufactured by Wako Pure Chemical Industries, Ltd.). And moved through 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 refraction detector were detected. Using a 5th order approximate curve prepared using standard polystyrene (manufactured by Tosoh Corporation, molecular weight as PE-converted molecular weight using Q factor) as a calibration curve, integrated molecular weight distribution curve, differential molecular weight distribution curve, number Average molecular weight (Mn) and weight average molecular weight (Mw) were calculated.

  Regarding the analysis method of such GPC method, technical report No. 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 (hereinafter simply abbreviated as MS) of the low density polyethylene (a) measured at a temperature of 130 ° C. and a take-up speed of 10 m / min is in the range of 40 to 120 mN, more preferably 50 to It is in the range of 100 mN, most preferably 60-90 mN. If the polyethylene-based resin for extrusion lamination has an MS of less than 40 mN, the laminate processability is inferior, which is not preferable, and if it exceeds 120 mN, the foam appearance is inferior.

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

  You may mix | blend other polyolefins, such as an ethylene-alpha-olefin copolymer, with the low density polyethylene (a) which comprises the (A) layer of the laminated body for foaming of this invention.

  When the polyolefin is mixed with the low density polyethylene (a), a pellet mixture obtained by mixing the pellets of the low density polyethylene (a) and the pellets of the polyolefin in a solid state may be used. A mixture obtained by melt-kneading with a kneader, Banbury or the like is preferable because a product with stable quality is obtained. When using a melt kneader, the melting temperature is preferably about the melting point of the polyolefin resin to about 300 ° C.

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

  The foamed laminate of the present invention becomes a foamed laminate when the layer (A) is foamed.

  The thickness before foaming of the layer (A) constituting the foaming laminate of the present invention is not particularly limited as long as the object of the present invention is achieved, but is excellent in foaming appearance, and therefore has a range of 60 to 150 μm. More preferably, it is 80-120 micrometers, More preferably, it is 80-100 micrometers.

  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 excellent heat insulation.

Although there is no limitation in particular about the paper base material which comprises the laminated body for foaming of this invention, since the expansion ratio of a low density polyethylene (a) can be improved, the basic weight of a paper base material is 150-400 g / m. ² is more preferable, and 250 to 350 g / m ² is more preferable.

Although there is no restriction | limiting in particular about the water | moisture content contained in such a paper base material, it is preferable that it is 15-30 g / m < ² > from the foaming magnification of low density polyethylene (a) improving, More preferably, 20-20. 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.

  Examples of the method for obtaining a laminate by an extrusion laminate molding method include various extrusion lamination methods such as a single lamination method, a tandem lamination method, a sandwich lamination method, and a coextrusion lamination method. 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 immediately below the T-die when extrusion laminating the low density polyethylene (a) is excellent in foam appearance, and is preferably in the range of 240 to 310 ° C, more preferably 250 to 300 ° C, most preferably. It is the range of 260-290 degreeC.

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

In such an extrusion laminating process, immediately after the polyethylene-based resin is made into an extruded layer in a molten state, the base material adhesion surface of the layer is exposed to an oxygen-containing gas or an ozone-containing gas, and a method of bonding to the base material is used. It is preferable because of excellent adhesiveness with the base material layer. When the adhesiveness between the thermoplastic resin and the substrate is improved by the ozone-containing gas, the ozone gas treatment amount 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.

  The extrusion laminating method in the method of obtaining the laminate of the present invention further improves the adhesiveness between the thermoplastic resin layer and the base material layer, so that the polyethylene resin does not foam, for example, 3 to 60 ° C. Heat treatment can be performed at a temperature for 10 hours or more. Moreover, you may perform well-known surface treatments, such as a corona treatment, a flame treatment, and a plasma treatment, with respect to the adhesive surface of a paper base material as needed. If necessary, an anchor coating agent may be applied to the paper substrate.

  As a method of obtaining the foamed laminate of the present invention, water resistance is applied to the paper substrate before laminating the low-density polyethylene (a) to the paper substrate layer, because the foamed laminate is excellent in heat insulation and economy. May be.

  The method of applying moisture is not particularly limited as long as the object of the present invention is achieved, and examples thereof include methods using a roll coater, a lip coater, a spray device, a die coater, a gravure device, a dampening device, and the like. be able to. A method using a dampening device is preferable because the amount of water applied is uniform.

  Such a dampening apparatus includes, for example, a product name “High Rotor S” from Suzuki Sangyo Co., Ltd., a product name “WEKO Rotor Dampening” from Nikka Co., Ltd., and a trade name “Toko Electronics Co., Ltd.” "TSD-3000" is sold.

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 expansion ratio of the low density polyethylene (a) can be increased, and the paper base material and the low density polyethylene (a) Therefore, 1.5 to 30 g / m ² is preferable, and 3 to 15 g / m ² is more preferable.

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

  As a heating method in the method of obtaining the foamed laminate of the present invention by heat foaming, in addition to hot air, electric heat, electron beam, the laminate is formed into a container shape, and the heat of the filling is used by filling a hot object. Any means can be used. Heating can be performed by a batch method in an oven, a continuous method using a conveyor, or the like.

  The heat source for heating is not particularly limited as long as this object is achieved, and examples of the laminated body and molded container include hot air, electric heat, and electron beam, and the container formed with the laminated body contains a high-temperature object. For example, the heat of the filling can be used. Further, the heating method can be performed by a batch method in an oven, a continuous method using a conveyor, or the like.

Conditions such as the heating temperature and the heating time are not particularly limited as long as the object of the present invention is achieved. In general, when hot air is used as a heat source, the heating temperature is not less than the melting point of the low density polyethylene (a) to 150. C. or less, 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 in that it comprises at least (A) layer / paper substrate, and (A) other components as well as those comprising only two components of the layer and paper substrate. For example, (B) layer and (C) layer may be included. Specifically, (A) layer / paper substrate / (B) layer, (A) layer / paper substrate / (B) layer / (A) layer, (B) layer / paper substrate / (A) Layer / (B) layer, (A) layer / paper substrate / (B) layer / (B) layer, (A) layer / (A) layer / paper substrate / (B) layer, (A) layer / Paper substrate / (B) layer / (C) layer, (B) layer / paper substrate / (A) layer / (C) layer, (C) layer / (B) layer / paper substrate / (A) Layer / (B) layer / (C) layer, (A) layer / paper substrate / (B) layer / (C) layer / (B) layer / (A) layer, (B) layer / paper substrate / Examples include (A) layer / (C) layer / (A) layer / (B) layer. In addition, the symbol / between layers represents that it is an adjacent layer.

  Examples of the (B) layer and (C) layer include a layer formed from a synthetic polymer, a woven fabric, a nonwoven fabric, a metal foil, 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- Methacrylic acid 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 a layer formed from a synthetic polymer such as polyvinylidene chloride, polystyrene, polycarbonate, polyurethane, and cellulose resin. Further, these 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 films and sheets may be further printed using urethane ink or the like. Examples of the metal foil include aluminum foil and copper foil, and examples of paper include kraft paper, fine paper, stretched paper, glassine paper, paperboard such as base paper for cups and photographic paper.

  Among these, since it is excellent in heat insulation, the layer (B) is made of polyethylene-based resin (b), polypropylene-based resin, polyester-based resin, polyamide-based resin, and these polymer films with aluminum deposition, alumina deposition, A film subjected to silicon dioxide vapor deposition and a metal foil are preferred, and polyethylene resin (b) is more preferred.

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 the range of 945-965 kg / m < ³ >.

  The polyethylene resin (b) is an ethylene homopolymer, an ethylene / α-olefin copolymer, or a composition thereof, and the molecular chain may be linear or branched. . Such a polyethylene-based resin (b) is not particularly limited, and it is sufficient that the density range is not exceeded.

  Examples of the ethylene homopolymer include medium / low pressure ethylene homopolymer and high pressure low density polyethylene. The medium / low pressure ethylene homopolymer can be obtained by a conventionally known medium / low pressure ion polymerization method. Moreover, 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, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene and the like can be mentioned, and one or more of these can be used.

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

Among these, because of excellent laminate moldability, 10 to 90 parts by weight of medium / high density polyethylene (e) having a density of 930 to 980 kg / m ³ and MFR of 1 to 20 g / 10 minutes, measured at 235 ° C. An ethylene resin composition (g) ((e) and (f) containing 90 to 10 parts by weight of a high-pressure method low-density polyethylene (f) having a swell ratio (hereinafter simply referred to as SR) of 1.50 to 2.20 ) Is preferably 100 parts by weight).

  Medium / high-density polyethylene is an ethylene homopolymer 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 Philips catalyst, or a metallocene catalyst. -An alpha olefin copolymer is illustrated.

  In addition, in the medium / high-density polyethylene (e), the MFR is preferably in the range of 6 to 100 g / 10 minutes, more preferably in the range of 8 to 60 g / 10, since the ethylene-based resin composition (g) is excellent in laminate processability. The range of minutes.

Furthermore, 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) has excellent laminate processability and productivity. preferable.

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

Moreover, 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 film-forming stability of the ethylene-based resin composition (g) is excellent.

  Further, the SR of the high-pressure method low-density polyethylene (f) is preferably 1.50 to 2.20, and preferably 1.75 to 2.20 because the film-forming stability of the ethylene-based resin composition (g) is excellent. A range is more preferable, and a range of 1.90 to 2.20 is most preferable.

This SR uses the melt indexer used in JIS K6922-1 (1997), extrudes the resin filled in the device under the conditions of a temperature of 235 ° C. and an extrusion rate of 3 g / min, and installs directly under the orifice. The strand-shaped extrudate is collected with a graduated cylinder containing isopropanol and the diameter (D) of the strand is divided by the orifice diameter (D ₀ ) of the melt indexer.

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

  Further, the polyolefin 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 of laminate moldability and laminate appearance. It is preferable from the point.

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

  Further, the polyethylene-based resin (b) may contain additives generally used for polyolefin resins such as an antioxidant, a light stabilizer, an antistatic agent, a lubricant, and an antiblocking agent as necessary. It may be added within a range that does not impair.

  The method for forming such a layer (B) is not particularly limited, and examples thereof include various laminating methods such as an extrusion laminating method, a dry laminating method, a thermal laminating method, and a wet laminating method.

  The thickness of the layer (B) is not particularly limited as long as the object of the present invention is achieved. However, the thickness of the layer (B) is 20 to 100 μm because it has excellent foaming properties and small problems such as breakage. The range of 20 to 50 μm is most preferable from the viewpoint of economy.

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

  The foamed laminate of the present invention is highly productive and becomes a foamed laminate that exhibits good thermal insulation and foam appearance when foamed.

It is a figure which shows the foaming cell shape whose foaming external appearance is favorable. It is a figure which shows the foam cell shape which is a foam appearance defect.

Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these.
(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 integral molecular weight distribution curve by GPC method, number average molecular weight (Mn) and weight average molecular weight (Mw) According to the method described in the detailed description of the present invention, the integral molecular weight distribution curve, Mn, Mw of low density polyethylene 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 and the ratio of components having a molecular weight of 1 million or more contained in low density polyethylene were calculated.
(4) Melt tension (MS)
A capillary viscometer with a barrel diameter of 9.55 mm equipped with a die and a heat retaining chamber with a length of 8 mm, a diameter of 2.095 mm, an inflow angle of 90 °, and a temperature set at 130 ° C. in a thermostatic chamber set at 23 ° C. (Toyo Seiki Seisakusho, trade name: Capillograph) is filled with 18 g of polyethylene resin, the piston lowering speed is set to 10 mm / min, the take-up speed is set to 10 m / min, and the load (mN) required for take-up is melt tension (MS ).
(5) Heating foaming A gear aging tester (No. 102-SHF-77 manufactured by Yasuda Seiki Seisakusakusho Co., Ltd.), in which a sample obtained by cutting the laminate obtained in the example into 10 cm × 20 cm and forming it into a cylindrical shape was heated to a predetermined temperature. The mixture was allowed to stand for a predetermined time while applying hot air therein, and then taken out and cooled to room temperature in air.
(6) Water content of paper base material The paper base material before lamination of the polyethylene resin was measured by using a Karl Fischer method water measuring device (trade name CA-05, manufactured by Mitsubishi Chemical Corporation). The measurement temperature is 165 ° C.
(7) Foam Layer Thickness Samples were taken of the foam molded at a processing speed of 80 m / min obtained in Examples and the laminate laminate before foaming as a blank, 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 five locations.
(8) State of foam 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 smoothness of the surface was good was rated as ◎, the case where it was slightly good as ○, the case where it was good but slightly inferior as Δ, and the case where it was poor as x.
(9) Maximum processing speed After peeling high-density polyethylene (B) from the obtained foam, methanol (Kishida Chemical Co., Ltd.) was added so that methylene blue (Kishida Chemical Co., Ltd., first grade) was 0.1% by weight. The paper base material was dyed with a methylene blue solution diluted with a 1st grade manufactured by Co., Ltd. Using a digital camera (COOLPIX995 manufactured by Nikon Corporation) mounted on a stereomicroscope (SMZ-2T manufactured by Nikon Corporation), the surface of the foamed layer of the stained sample was observed at a magnification of 25 times. 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. The processing speed that could be maintained was defined as the maximum processing speed (m / min). The maximum processing speed was evaluated as good at 80 m / min or more.

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

First, (A1) is supplied to a single-screw extrusion laminator (manufactured by Musashinokikai Co., Ltd.) having a screw with a diameter of 90 mmφ, and extruded from the T die so that the resin temperature immediately below the T die is 305 ° C. A predetermined take-up speed (60 to 110 m / min, every 5 m / min) and an air gap length of 130 mm on a paper substrate having a basis weight of 320 g / m ² and a thickness of 70 μm is 6 / m ² Extrusion lamination was performed. Further, (B1) was supplied to a single screw extruder (made by Musashinokikai Co., Ltd.) having a screw having a diameter of 90 mmφ, and a temperature of 320 ° C., a take-up speed of 80 m / min, and an air gap length of 130 mm, (B1) The laminate was extruded so as to have a thickness of 40 μm, and a high-pressure method low-density polyethylene (A1), a paper base material, and a high-density polyethylene (B1) were laminated in this order. The obtained laminate was heated and foamed at 120 ° C. for 5 minutes to obtain a foam laminate. About the obtained foaming laminated body, the thickness of the foaming layer, the state of the foaming surface, and the maximum processing speed were evaluated. The evaluation results are shown in Table 1.

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

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

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

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

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

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

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

Comparative Example 3
As the resin of the layer (A), the MFR is 8 g / 10 min, the density is 920 kg / m ³ , the Mw / Mn is 6.76, the ratio of molecular weight is 100,000 or more is 28.9%, and the ratio of molecular weight is 1 million or more is 2. A foam laminate was obtained in the same manner as in Example 1 except that high-pressure low-density polyethylene (A9, manufactured by Tosoh Corporation) having 0.000% and MS of 160 mN was used. About the obtained foaming laminated body, the foaming layer thickness, foaming external appearance, and the maximum processing speed were evaluated. The evaluation results are shown in Table 2. The foam appearance and the maximum processing speed were inferior.

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

Comparative Example 5
(A) As a resin for the layer, high-pressure low-density polyethylene (A4) 50 parts by weight, MFR 14 g / 10 min, density 917 kg / m ³ , MS MS 117 mN A polyethylene resin composition (A11, MFR 18 g / 10 min) blended with polyethylene (manufactured by Tosoh Corp.) to 50 parts by weight and melt-kneaded with a single screw extruder (Placo Corp. caliber 50 mm), Except for using a density of 918 kg / m ³ , Mw / Mn of 8.55, a ratio of molecular weight of 100,000 or more is 34.5%, a ratio of molecular weight of 1 million or more is 1.27%, and MS is 95 mN). 1 was used to obtain a foam laminate. About the obtained foaming laminated body, the foaming layer thickness, foaming external appearance, and the maximum processing speed were evaluated. The evaluation results are shown in Table 2. The foam appearance and the maximum processing speed were inferior.

  The foamed 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 (5)

A foaming laminate comprising at least (A) layer / paper substrate layer, wherein the (A) layer is composed of low density polyethylene (a) satisfying the following (i) to (iii).
(I) The value of the ratio Mw / Mn of the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured by GPC method is 5.00 or more and 8.50 or less (ii) Integrated molecular weight distribution measured by GPC method In the curve, the proportion of components having a molecular weight of 1,000,000 or more is 0.50% or more and 1.50% or less.
(Iii) MS at 130 ° C. is 40 mN or more and 120 mN or less. The foamed laminate according to claim 1, wherein the MFR of the low density polyethylene (a) is 7 g / 10 min or more and 30 g / 10 min or less. (A) A layer is comprised only from a high-pressure method low-density polyethylene (c), The laminated body for foaming in any one of Claims 1-2 characterized by the above-mentioned. The foaming laminated body in which the (A) layer of the laminated body for foaming in any one of Claims 1-3 is foaming. A heat-insulated paper container, wherein the foamed laminate according to claim 4 is used at least as a body member.

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