JP2009154472A - Multilayered blow molding and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic blow molding excellent in surface gloss and transparency, particularly a hollow container with a luxurious feeling, excellent in the gloss of a container outer surface layer and also in transparency, impact resistance, flexibility, and resistance to environmental stress cracking. <P>SOLUTION: The multilayered blow molding is formed of a stack comprising the following surface layer A, intermediate layer B and inner layer C: the surface layer A and the inner layer C are each made from a polyethylene (a) manufactured using a metallocene catalyst and having an MFR (a temperature of 190°C, a load of 2.16 kg) of 1.0 to 15 g/10 min and a density of 0.870 to 0.928 g/cm<SP>3</SP>, the ratio (Mw/Mn) of its weight average molecular weight to number average molecular weight being 1.5 to 4.0 by gel permeation chromatography (GPC) measurement; and the intermediate layer B is made from either a polyethylene manufactured using the Phillips catalyst or the Ziegler catalyst and having an MFR (a temperature of 190°C, a load of 2.16 kg) of 0.1 to 5 g/10 min and a density of 0.910 to 0.967 g/cm<SP>3</SP>, its Mw/Mn being 3.3 to 28 by GPC measurement, or a polyethylene (b) manufactured using high pressure method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a blow molded article and a method for producing the same, and more specifically, a high-class feeling excellent in gloss of an outer surface layer of a container, and excellent in transparency, impact resistance, flexibility, rigidity, and environmental stress crack resistance. The present invention relates to a production method capable of obtaining a multilayer blow-molded product (container) for shampoos, rinses, cosmetics, medical products, etc. with good handling without pinch-off peeling and parison stickiness.

  Conventionally, plastic hollow molded products have been widely used in the field of containers such as shampoos, rinses, cosmetics, and medical use. Resins such as polyethylene, polypropylene, and polyethylene terephthalate are widely used as plastics for hollow molded articles. Among these, polyethylene and polypropylene are used as preferable materials in terms of performance, price, and the like, and many materials and molded articles with improved surface gloss and transparency have been proposed (for example, see Patent Documents 1 to 11). ).

Japanese Patent Application Laid-Open No. 09-058648 (Patent Document 4) discloses that in a plastic bottle having at least an outer surface made of an olefin resin, the olefin resin has a specific formula Y <−AX + B (where Y is an olefin resin). Density (g / cm ³ ), X is the melt tension (g) of the olefin resin, A is a number of 0.0116, and B is a number of 0.962) And a plastic bottle having a gloss (60 ° gloss) of 60 ° or more on the outer surface of the bottle.
However, in such a case, an olefin resin satisfying a specific relationship between density and melt tension is disclosed, but the specific characteristics of the resin used for the surface layer and the specific characteristics of the resin used for the inner layer are not necessarily limited. It is not sufficiently described, and a molded product having a more satisfactory high gloss surface appearance cannot be obtained.

  Japanese Patent Application Laid-Open No. 09-077039 (Patent Document 5) contains 0.5 to 10.0% by weight of a polyethylene resin layer / pearl pigment in a density range of 0.915 to 0.940 in order from the outer layer. A multilayer blow container composed of a high-density polyethylene layer having a density of 0.941 or more / a layer containing recycled polyethylene containing 2.0 to 10.0% by weight of a color pigment has been proposed.

JP-A-10-315357 (Patent Document 8) discloses that at least one layer of a resin container composed of a single layer or a plurality of layers is manufactured using a metallocene catalyst and has a melt flow rate. it is 0.1 to 100 g / 10 min, density, exceed ^{0.915g / cm 3, 0.960g / cm} 3 or less, the differential elution curve to be obtained by temperature rising elution fractionation (TREF) The peak temperature is 65 ° C. or higher, the height of the peak is H, and the width of half of the peak height is W, the value of H / W is Resin formed of ethylene homopolymer or ethylene / C3-C40 α-olefin copolymer having a property of not less than 15 ° C. when it is 5 or more and W is expressed as a temperature range Produced containers are proposed .

Japanese Patent Application Laid-Open No. 10-235760 (Patent Document 6) contains high-pressure polyethylene having a density of 0.925 g / cm ³ or more and a melt flow rate of 0.3 to 10 g / 10 min. There has been proposed a heat sterilization blow bag formed by blow molding a laminate of an intermediate layer and an inner and outer layer containing another olefin resin having a melting point of 113 ° C. or higher.
However, in the case of these containers, since the density of the resin on the surface layer is high, a molded product that is satisfactory in terms of flexibility, soft touch, touch, etc. is not always obtained.

JP 2000-355045 (Patent Document 9) discloses polyethylene having a melt flow rate of 4 g / 10 min or less obtained by copolymerizing ethylene and high α-olefin with a metallocene catalyst, and a metallocene catalyst. At least one composition comprising a polyethylene having a melt flow rate of 10 g / 10 min or more obtained by copolymerizing ethylene and a high α-olefin in a weight ratio of 98: 2 to 60:40. A hollow molded product formed by blow molding a parison has been proposed.
However, in the case of this container, since the resin used for the surface layer is a composition composed of two types of polyethylene having different melt flow rates polymerized using a metallocene catalyst, the resulting molecular weight distribution is large, It is not always possible to obtain a molded article that is satisfactory in terms of gloss and transparency.

JP 05-008354 A JP 05-310241 A JP-A-08-091341 JP 09-058648 A Japanese Patent Laid-Open No. 09-0707039 Japanese Patent Laid-Open No. 10-235760 JP-A-10-236451 Japanese Patent Laid-Open No. 10-315357 JP 2000-355045 A JP 2003-089177 A JP 2003-095240 A

  The object of the present invention is a plastic molded article that solves the above problems, has excellent gloss of the outer surface layer of the container, has excellent transparency and design of the intermediate layer, and can reduce the thickness of the resin used for the surface layer. In addition, high-quality plastic molded products with excellent transparency, impact resistance, flexibility, and environmental stress crack resistance, and glossiness, high glossiness with depth without unevenness, and flexibility Shampoos, rinses, cosmetics, medical containers, etc. that are excellent in terms of soft touch, feel, etc., excellent in physical properties such as drop impact strength, and that do not cause problems such as whitening when deformed by external force applied to the container It is an object of the present invention to provide a production method that can be obtained with good handleability without causing pinch-off peeling or parison stickiness.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have obtained a multilayer blow molded product in which a laminate composed of a surface layer, an intermediate layer, and an inner layer is formed. The MRF, density, and Mw / Mn to be formed are simultaneously melted and the parison is extruded under specific conditions, and then blow molded to prevent pinch-off peeling and parison stickiness. It has been found that a plastic molded article having excellent transparency and a balance with the resin of the intermediate layer can be obtained having a glossy, non-uniform and deep appearance, and the present invention has been completed.

According to the first invention of the present invention, there is provided a multilayer blow-molded article formed by a laminate comprising the following surface layer (A), intermediate layer (B) and inner layer (C), wherein the surface layer (A) and The inner layer (C) has an MFR (temperature 190 ° C., load 2.16 kg) of 1.0 to 15 g / 10 min, a density of 0.870 to 0.928 g / cm ³ , and gel permeation chromatography ( The ratio (Mw / Mn) of weight average molecular weight to number average molecular weight (Mw / Mn) by GPC) measurement is 1.5 to 4.0, and the intermediate layer (B) is made of MFR. (Temperature 190 ° C., load 2.16 kg) is 0.1 to 5 g / 10 min, density is 0.910 to 0.967 g / cm ³ , and Mw / Mn by gel permeation chromatography (GPC) measurement 3.3 Is 28, polyethylene was prepared in Phillips catalyst or a Ziegler catalyst, or a polyethylene produced (b) in a high pressure process, the multilayer blow-molded article is provided, characterized in that.

According to the second invention of the present invention, in the first invention, the polyethylene (a) has a viscosity of 460 to 4200 Pa · sec measured at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ using a capilograph. A multilayer blow-molded article is provided.
According to a third invention of the present invention, in the first or second invention, the polyethylene (b) has a viscosity of 1000 to 6000 Pa · sec measured at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ using a capilograph. A multilayer blow-molded article according to claim 1 or 2 is provided.

According to a fourth invention of the present invention, there is provided a multilayer blow molded product characterized in that in any one of the first to third inventions, the thickness of the surface layer (A) is 10 μm or more.
According to the fifth invention of the present invention, in any one of the first to fourth inventions, the thickness of the surface layer (A) is 3 to 87% with respect to the entire thickness of the laminate, and the intermediate layer (B). The multilayer blow-molded product is characterized in that the thickness of the inner layer (C) is 10 to 94% with respect to the entire thickness of the laminate, and the thickness of the inner layer (C) is 3 to 87% with respect to the entire thickness of the laminate. Is done.

According to a sixth invention of the present invention, in any one of the first to fifth inventions, the gloss value (incident angle 60 °) of the surface of the molded product is 30% or more. Is provided.
According to the seventh invention of the present invention, in any one of the first to sixth inventions, the total thickness portion of the molded article body has a haze of 50% or less and a total light transmittance of 70% or more. A featured multilayer blow molded article is provided.

Furthermore, according to the eighth aspect of the present invention, there is provided a method for producing a multilayer blow molded article formed by a laminate including a surface layer (A), an intermediate layer (B), and an inner layer (C), The following polyethylene (a) is selected for A) and the inner layer (C), and the following polyethylene (b) is selected for the intermediate layer (B). After simultaneous melting, the parison is extruded so that the surface temperature is 240 ° C. or lower. Then, the manufacturing method of the multilayer blow molded article characterized by performing blow molding continuously is provided.
Polyethylene (a): MFR (temperature 190 ° C., load 2.16 kg) is 1.0 to 15 g / 10 min, density is 0.870 to 0.928 g / cm ³ , and gel permeation chromatography (GPC) ) Polyethylene (b) produced with a metallocene catalyst having a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) of 1.5 to 4.0: MFR (temperature 190 ° C., load 2.16 kg) ) Is 0.1 to 5 g / 10 min, density is 0.910 to 0.967 g / cm ³ , and Mw / Mn by GPC measurement is 3.3 to 28. Polyethylene made by high pressure method

According to the present invention, the multilayer blow-molded product is made of polyethylene having specific physical properties, and is composed of a surface layer, an intermediate layer, and an inner layer of a specific material. In addition, the balance with the resin of the intermediate layer can achieve a glossy, uniform and deep appearance, and has a high-class feeling with excellent transparency, impact resistance, flexibility, and environmental stress crack resistance. A plastic molded product is obtained.
In particular, it is possible to obtain a plastic molded product having excellent gloss and transparency of the outer surface layer of the container, excellent design, few fine irregularities on the inner surface of the inner layer, and high pinch-off strength.
In addition, polyethylene produced with a metallocene catalyst was selected for the surface layer and inner layer, and polyethylene produced with a Phillips catalyst or Ziegler catalyst or polyethylene produced by a high pressure method was selected for the intermediate layer. Afterwards, the parison is extruded under specific conditions, and then blow-molded, so that it not only has high gloss with no unevenness, but also has excellent handling, flexibility, soft touch, feel, drop impact strength, etc. It is excellent, and when a container is deformed by applying an external force, a molded product that does not cause problems such as whitening can be obtained with high productivity, and its industrial utility is very high.

The present invention is described in detail below.
The multilayer blow molded article of the present invention is a multilayer blow molded article formed by a laminate comprising the following surface layer (A), intermediate layer (B) and inner layer (C),
The surface layer (A) and the inner layer (C) have an MFR (temperature 190 ° C., load 2.16 kg) of 1.0 to 15 g / 10 min, a density of 0.870 to 0.928 g / cm ³ , and a gel A ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) measured by permeation chromatography (GPC) (Mw / Mn) is 1.5 to 4.0, and comprises polyethylene (a) produced with a metallocene catalyst,
The intermediate layer (B) has an MFR (temperature 190 ° C., load 2.16 kg) of 0.1 to 5 g / 10 min, a density of 0.910 to 0.967 g / cm ³ , and gel permeation chromatography. (GPC) Mw / Mn by measurement is 3.3 to 28, and is made of polyethylene produced by a Phillips catalyst or Ziegler catalyst, or polyethylene (b) produced by a high pressure method.

1. Polyethylene material constituting each layer (1) Polyethylene constituting the surface layer (A) (a)
The MFR of the polyethylene (a) produced with the metallocene catalyst that forms the surface layer (A) of the present invention is 1.0 to 15 g / 10 minutes, preferably 2.0 to 10 g / 10 minutes, and more preferably. Is 3.0 to 7.0 g / 10 min. Here, MFR is a measured value at a temperature of 190 ° C. and a load of 2.16 kg in accordance with JIS K6922-2: 1997.
If the MFR of the polyethylene of the surface layer (A) is less than 1.0 g / 10 min, the surface of the molded product tends to be rough, and if it exceeds 15 g / 10 min, the surface of the extruded parison tends to be sticky. This causes problems such as contamination of the surface of the molding container, foreign matter adhering to the surface easily, air bleeding in the mold cavity becoming worse, and uneven patterns in the molded container.

The density of the polyethylene (a) is a 0.870~0.928g / cm ^3, preferably 0.900~0.922g / cm ^3, more preferably 0.910~0.920g / cm ³ , and when the surface flexibility is required, 0.905 to 0.915 g / cm ³ is preferable. Here, the density is measured in accordance with JIS K6922-1 and 2: 1997. When the density of the polyethylene of the surface layer (A) is less than 0.870 g / cm ³ , the rigidity of the multilayer molded container is inferior, the buckling strength tends to decrease, or the heat resistance tends to decrease, and 0.928 g / cm ³ is reduced. If it exceeds, the crystallization speed will be high and it will be difficult to remove air from the mold cavity surface, and uneven surfaces will be easily formed on the surface of the molded product.

  Furthermore, the ratio (Mw / Mn) of the weight average molecular weight and the number average molecular weight according to GPC measurement of the polyethylene (a) of the surface layer (A) is 1.5 to 4.0, preferably 2.0 to 3.5, Preferably it is 2.5-3.3. When Mw / Mn by GPC measurement of polyethylene of the surface layer (A) is less than 1.5, melt fracture tends to occur in the parison, and when it exceeds 4.0, the surface skin of the parison tends to be finely roughened.

In the present invention, the ratio (Mw / Mn) between the weight average molecular weight and the number average molecular weight of polyethylene (a) is determined by the following gel permeation chromatography (GPC) measurement.
Use (i) Measurement Conditions c _o Tazu Inc. Model 150C, subjected to GPC measurement under the following conditions to determine the weight average molecular weight (Mw).
Column: Shodex HT-G (manufactured by Showa Denko KK) and HT-806M (manufactured by Showa Denko KK) x 2 Solvent: 1,2,4-trichlorobenzene Temperature: 140 ° C.
Flow rate: 1.0 ml / min Injection volume: 300 μl
(Ii) Sample preparation Approximately 3 mg of a sample and 3.0 ml of a solvent were weighed into a commercially available 4 ml screw top vial, and shaken at a temperature of 150 ° C. for 2 hours using an SSC-9300 type stirrer manufactured by Senshu Kagaku.
(Iii) Calculation of molecular weight GPC chromatographic data is loaded into a computer at a frequency of 1 point / second, processed according to the description in Chapter 4 of “Size Exclusion Chromatography” published by Sadao Mori and Kyoritsu Shuppan Co., Ltd. The value was calculated.
(Iv) Column calibration Monolithic polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S, manufactured by Showa Denko K.K.) -66.0, S-28.5, S-5.05), each 0.2 mg / l solution of n-eicosane and n-tetracontane, a series of monodisperse polystyrene measurements were taken and their A calibration curve was obtained by fitting the relationship between the elution peak time and the logarithm of molecular weight with a quartic polynomial.
In addition, the molecular weight of polystyrene was converted into the molecular weight of polyethylene using the following formula.
M _PE = 0.468 × M _PS

Furthermore, the viscosity of the polyethylene (a) of the surface layer (A) is measured at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ using a capillograph, and is 460 to 4200 Pa · sec, preferably 700 to 3500 Pa · sec, more preferably 1000. ~ 3000 Pa · sec. If the viscosity is less than 460 Pa · sec, the surface of the extruded parison tends to be sticky, the tip of the die may become dirty, or foreign matter may easily adhere to the surface, resulting in poor air venting in the mold cavity. When a concavo-convex pattern is generated in the molded container and exceeds 4200 Pa · sec, the surface of the molded product tends to be rough.
The viscosity by a caprograph is obtained by using a caprograph, using a nozzle with a nozzle diameter of 1 mmφ, and measuring at a land length of 20 mm, an inflow angle of 90 °, a measurement temperature of 190 ° C., and a shear rate of 23 sec ⁻¹ . The capilograph referred to in the present invention indicates the melt viscosity of the resin, and means the fluidity of the resin in the screw and die head during molding.

(2) Polyethylene constituting the intermediate layer (B) (b)
The polyethylene (b) of the intermediate layer (B) is a polyethylene produced by a Phillips catalyst or a Ziegler catalyst, or a polyethylene produced by a high pressure method, and has an MFR of 0.1 to 5 g / 10 min, preferably 0.2. It is -3.0g / 10min, More preferably, it is 0.3-1.5g / 10min.

  When the MFR of the polyethylene (b) of the intermediate layer (B) is less than 0.1 g / 10 minutes, a scale pattern is likely to occur between the surface layer (A) and the inner layer (C). In addition, the temperature of the extruded parison is increased, which adversely affects pinch-off. When the MFR exceeds 5 g / 10 min, a scale-like pattern is hardly generated, but the drawdown resistance tends to be deteriorated, and it is difficult to adjust the thickness at the time of molding.

The density of polyethylene (b) in the intermediate layer (B) is 0.910 to 0.967 g / cm ³ , preferably 0.920 to 0.958 g / cm ³ , more preferably 0.925 to 0. 0.952 g / cm ³ , particularly 0.910 to 0.930 g / cm ³ when flexibility of the container is required, and 0.930 to 0.967 g / cm ³ when rigidity is required. is there. When the density of the polyethylene (b) of the intermediate layer (B) is less than 0.910 g / cm ³ , the rigidity of the multilayer molded container is inferior, the buckling strength tends to decrease, and the heat resistance tends to decrease, 0.967 g If it exceeds / cm ³ , the transparency tends to decrease.

  Mw / Mn by GPC measurement of polyethylene of the intermediate layer (B) is 3.3 to 28, preferably 4 to 20, and more preferably 5 to 15. If Mw / Mn is less than 3.3, melt fracture tends to occur in the parison, and if it exceeds 28, the surface layer (A) is affected and fine irregularities tend to occur on the parison surface skin.

Further, the polyethylene viscosity of the intermediate layer (B) is measured at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ using a capillograph, and is 1000 to 6000 Pa · sec, preferably 1800 to 5000 Pa · sec, more preferably 2500 to 4000 Pa · sec. sec. When the viscosity is out of the above range, a scaly pattern is likely to occur between the surface layer (A) or the inner layer (C). If the viscosity is less than 1000 Pa · sec, the drawdown resistance tends to deteriorate, and it becomes difficult to adjust the thickness during molding. If it exceeds 6000 Pa · sec, the resin temperature of the parison increases and the pinch-off thickness becomes thin and the strength tends to decrease. Become.

  The value of the melt flow rate of the polyethylene (a) of the surface layer (A) and the inner layer (C) with respect to the melt flow rate of the polyethylene (b) of the intermediate layer (B) of the present invention is 1.0 to 60, preferably 2.0. -40, more preferably 3.0-20. If this value is less than 1.0, the intermediate layer has an unevenness in the intermediate layer when the MFR value of the intermediate layer resin and the inner layer resin is low, and if the combination has a high MFR value, it is drawn down and the molded product at the time of blow molding It becomes difficult to adjust the wall thickness. On the other hand, if it exceeds 60, melt fracture at the interface between the intermediate layer (B) and the inner layer (C) tends to occur, and the thickness of the intermediate layer (B) is reduced in the ratio of the intermediate layer (B) to the inner layer (C). Can not be thinned.

(3) Polyethylene constituting the inner layer (C) The polyethylene constituting the inner layer (C) of the present invention is a polyethylene produced with a metallocene catalyst, and its MFR is 1.0 to 15 g / 10 min, preferably Is 2.0 to 10 g / 10 min, more preferably 3.0 to 7.0 g / 10 min.
If the MFR of the polyethylene of the inner layer (C) is less than 1.0 g / 10 min, the inner surface of the molded product tends to be rough, and if it exceeds 15 g / 10 min, the inner surface of the extruded parison tends to be sticky. There is a risk that the tip of the die is soiled, foreign matters are likely to adhere to the inner surface, air venting in the mold cavity is worsened, and uneven patterns are generated in the molding container. In addition, there arises a problem that the thickness of the pinch-off on the inner surface is reduced.

Further, the density of the polyethylene of the inner layer (C), a 0.870~0.928g / cm ^3, preferably 0.900~0.922g / cm ^3, more preferably 0.910~0.920g / cm ^3, and if the flexibility of the surface is determined 0.905～0.915G / cm ³ are preferred. If the density of the polyethylene of the inner layer (C) is less than 0.870 g / cm ³ , the multilayer molded container has poor rigidity, the buckling strength tends to decrease, and the heat resistance tends to decrease, and 0.928 g / cm ³ is reduced. If it exceeds, the crystallization speed will be high and it will be difficult to remove air from the mold cavity surface, and uneven surfaces will be easily formed on the surface of the molded product.

  Furthermore, the ratio (Mw / Mn) of the weight average molecular weight and the number average molecular weight as measured by GPC of polyethylene of the inner layer (C) is 1.5 to 4.0, preferably 2.0 to 3.5, more preferably 2 .5 to 3.3. If Mw / Mn by GPC measurement of polyethylene of the inner layer (C) is less than 1.5, melt fracture tends to occur in the parison, and if it exceeds 4.0, the inner surface skin of the parison tends to be finely roughened.

Furthermore, the viscosity of the polyethylene of the inner layer (C) is measured at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ using a capillograph, and is 460 to 4200 Pa · sec, preferably 700 to 3500 Pa · sec, more preferably 1000 to 3000 Pa · sec. sec. If the viscosity is less than 460 Pa · sec, the inner surface of the extruded parison tends to be sticky, which may cause the tip of the die to become dirty, or foreign matter may easily adhere to the inner surface. If it becomes worse and a concavo-convex pattern occurs in the molded container and exceeds 4200 Pa · sec, the inner surface of the molded product tends to be rough.

  In the present invention, the polyethylene of the surface layer (A) and the polyethylene of the inner layer (C) may be the same or different.

2. Production method of polyethylene material Polyethylene constituting the surface layer (A), intermediate layer (B) and inner layer (C) of the present invention is ethylene homopolymerization or ethylene and an α-olefin having 3 to 12 carbon atoms, such as propylene. , 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Also, copolymerization with a diene for the purpose of modification is possible. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene, and the like. The comonomer content during the polymerization can be arbitrarily selected. For example, in the case of copolymerization of ethylene and an α-olefin having 3 to 12 carbon atoms, an ethylene / α-olefin copolymer is used. The α-olefin content therein is 0 to 40 mol%, preferably 0 to 30 mol%.

The polyethylene used for the surface layer (A) of the present invention is polymerized using a metallocene catalyst. A metallocene catalyst is a type of catalyst called a single-site catalyst that has a relatively single active site, and is typically a transition metal metallocene complex, such as a biscyclopentadienyl complex of zirconium or titanium. A catalyst obtained by reacting methylaluminoxane or the like as a cocatalyst can be mentioned, and it is a homogeneous or heterogeneous catalyst in which various complexes, cocatalysts, carriers and the like are variously combined.
Examples of the metallocene catalyst include JP-A-58-19309, 59-95292, 59-23011, 60-35006, 60-35007, 60-35008, and 60-35009. No. 61-130314 and JP-A-3-163088, and the like.

  The polyethylene (b) used in the intermediate layer (B) of the present invention can be produced using various catalysts such as a Ziegler catalyst and a Phillips catalyst. Any polymerization catalyst can be used as long as hydrogen exhibits a chain transfer action of olefin polymerization.

Specifically, any catalyst that is composed of a solid catalyst component and an organometallic compound and that is suitable for slurry-based olefin polymerization such that hydrogen exhibits a chain transfer action of olefin polymerization can be used. Preferred is a heterogeneous catalyst in which polymerization active sites are localized.
The solid catalyst component is not particularly limited as long as it is used as a solid catalyst for olefin polymerization containing a transition metal compound. As the transition metal compound, compounds of elements of Group 4 to Group 10 of the periodic table, preferably Group 4 to Group 6, can be used, and specific examples include Ti, Zr, Hf, V, Cr. And compounds such as Mo.

  As a more preferable catalyst for obtaining the polyethylene used in the intermediate layer (B) of the present invention, a Cr-containing catalyst, particularly a Philips catalyst is preferable. Those molded with polyethylene using a Philips catalyst (chromium-based catalyst) are less likely to have a scale pattern on the parison than polyethylene using other catalysts.

  As the polymerization catalyst for polyethylene used in the inner layer (C) of the present invention, the same kind of metallocene catalyst as that used in the production of the polyethylene of the surface layer (A) is used.

The polyethylene of the present invention can be produced by a production process such as a gas phase polymerization method, a solution polymerization method, or a slurry polymerization method. Among the polymerization conditions of the ethylene polymer, the polymerization temperature can be selected from the range of 0 to 300 ° C. The polymerization pressure can be selected from the range of atmospheric pressure to about 100 kg / cm ² . It is selected from aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, etc. in a state where oxygen and water are substantially cut off. It can be produced by polymerizing ethylene and α-olefin in the presence of an inert hydrocarbon solvent.
In the above polymerization, hydrogen supplied to the polymerization vessel is consumed as a chain transfer agent, determines the average molecular weight of the produced ethylene-based polymer, and partly dissolves in a solvent and is discharged from the polymerization vessel. The solubility of hydrogen in the solvent is small, and the hydrogen concentration near the polymerization active point of the catalyst is low unless a large amount of gas phase is present in the polymerization vessel. Therefore, if the hydrogen supply amount is changed, the hydrogen concentration at the polymerization active point of the catalyst changes rapidly, and the molecular weight of the produced ethylene polymer changes following the hydrogen supply amount in a short time. Therefore, a more homogeneous product can be produced by changing the hydrogen supply rate in a short cycle. Moreover, the aspect of changing the hydrogen supply amount is preferably changed discontinuously rather than continuously because the effect of broadening the molecular weight distribution can be obtained.
In the ethylene polymer according to the present invention, it is important to change the hydrogen supply amount, but other polymerization conditions such as polymerization temperature, catalyst supply amount, supply amount of olefin such as ethylene, 1-butene It is also important to change the supply amount of the comonomer and the like, the supply amount of the solvent, etc., simultaneously with the change of hydrogen or separately.

  The MFR of the polyethylene of the present invention can be adjusted by the ethylene polymerization temperature, the use of a chain transfer agent, etc., and a desired product can be obtained. That is, by increasing the polymerization temperature of ethylene and α-olefin, the molecular weight can be decreased, and as a result, the MFR can be increased. By decreasing the polymerization temperature, the molecular weight can be increased, and as a result, the MFR can be decreased. . In addition, the molecular weight can be lowered by increasing the amount of hydrogen coexisting in the copolymerization reaction of ethylene and α-olefin (chain transfer agent amount), resulting in an increase in MFR, and the amount of hydrogen coexisting (chain transfer). The molecular weight can be increased by decreasing the (drug amount), and as a result, the MFR can be reduced.

  The density of the polyethylene of the present invention can be obtained by changing the density and the amount of comonomer copolymerized with ethylene, and can be reduced by increasing the amount of comonomer.

  Increasing Mw / Mn by GPC measurement of the polyethylene of the present invention can be achieved by mixing components having different molecular weights.

The viscosity of the polyethylene of the present invention is measured using a caprograph at a temperature of 190 ° C. and a shear rate of 23 sec ⁻¹ , and can be adjusted by the ethylene polymerization temperature, the use of a chain transfer agent, and the like to obtain a desired one. Can do. That is, by increasing the polymerization temperature of ethylene and α-olefin, the molecular weight can be decreased, and as a result, the viscosity can be decreased. By decreasing the polymerization temperature, the molecular weight can be increased, and as a result, the viscosity can be increased. Can do. In addition, by increasing the amount of hydrogen that coexists in the copolymerization reaction of ethylene and α-olefin (amount of chain transfer agent), the molecular weight can be lowered, and as a result, the viscosity can be reduced. The molecular weight can be increased by decreasing the amount of transfer agent), and as a result, the viscosity can be increased.

In the case of the polyethylene used for the surface layer (A) or the inner layer (C), the ethylene polymer produced by the above method is preferably used alone, and the polyethylene used for the intermediate layer (B). In this case, one kind or a plurality of kinds may be mixed and used. After pelletizing by mechanical melt mixing with a pelletizer or a homogenizer, etc., according to a conventional method, molding is performed by various molding machines and desired molding is performed. Product.
In addition to the other olefin polymers and rubbers, etc., the ethylene polymer obtained by the above-mentioned method is not limited to antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, Clouding agent, anti-blocking agent, processing aid, color pigment, pearl pigment, glittering material, polarizing pearl pigment, crosslinking agent, foaming agent, neutralizing agent, heat stabilizer, crystal nucleating agent, inorganic or organic filler, flame retardant A known additive such as can be blended. As a coloring method, a compound added in a necessary amount to the base resin or a master batch added at a high concentration may be post-blended.

  As additives, for example, antioxidants (phenolic, phosphorus-based, sulfur-based), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like can be appropriately used in combination of one or more. As the filler, calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silica, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used. . In any case, various additives may be blended with the ethylene polymer as necessary, and the mixture may be kneaded with a kneading extruder, a Banbury mixer, or the like to obtain a molding material.

3. Manufacturing method of multilayer blow-molded article The manufacturing method of multilayer blow-molded article of the present invention is a method of manufacturing a multilayer blow-molded article formed by a laminate including a surface layer (A), an intermediate layer (B), and an inner layer (C). The following polyethylene (a) is selected for the surface layer (A) and the inner layer (C), and the following polyethylene (b) is selected for the intermediate layer (B). It is characterized by extruding the parison and subsequently blow molding.
Polyethylene (a): MFR (temperature 190 ° C., load 2.16 kg) is 1.0 to 15 g / 10 min, density is 0.870 to 0.928 g / cm ³ , and gel permeation chromatography (GPC) ) Polyethylene (b) produced with a metallocene catalyst having a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) of 1.5 to 4.0: MFR (temperature 190 ° C., load 2.16 kg) ) Is 0.1 to 5 g / 10 min, density is 0.910 to 0.967 g / cm ³ , and Mw / Mn by GPC measurement is 3.3 to 28. Polyethylene made by high pressure method

The multilayer blow molded product (multilayer container) of the present invention can be obtained by multilayer molding with a multilayer blow molding machine. Specifically, it can be achieved by using a blow molding machine having a head structure which is composed of two or more types of extruders and can form three or more types of layer structures. Furthermore, in addition to the structure having three layers of the surface layer (A), the intermediate layer (B), and the inner layer (C), a four-layer equipped with an extruder for a recycled resin layer using burrs generated during molding It may be a blow molding machine having a structured head. Further, when making a container with a gas barrier layer added, a multilayer blow molding machine in which an extruder is added or the layer structure of the head is changed may be used. The mold clamping device can be used with a device provided in a normal blow molding machine. Molding conditions can be set as appropriate depending on the size and shape of the molded product to be obtained. Also, printing with a screen on the multilayer container of the present invention, in-mold labels for inserting and molding a label in a mold during multilayer blow molding, You can decorate with shrink film as well as with shrink film.

As the cooling mold used for the production of the multilayer blow molded article of the present invention, a mold during normal blow molding can be used. The cavity surface of the mold is sandblasted, and is applied to remove the air existing between the mold cavity and the parison when the parison is sandwiched between the mold cavity surface and the parison is inflated with an air pin. There are many.
When the above polyethylene is used in the present invention, each mold having a surface roughness Ra value (measured in accordance with JIS-B0601: 1982) of the mold cavity surface of 0.2 to 0.9 μm. By performing the molding with, a glossy container having a depth without unevenness can be obtained. When the surface roughness Ra value of the mold cavity surface exceeds 0.9 μm, the mold cavity surface is transferred, and the surface of the molded container is reduced in gloss. Further, if the surface roughness Ra value is less than 0.20 μm, air bleeding is poor and a non-uniform pattern is generated on the surface of the molded container.

The size of the multilayer blow-molded product thus obtained is not particularly limited, but is preferably about 10 to 2000 ml. Further, the shape of the container is not particularly limited.
Moreover, unless it deviates from the objective of this invention, the said laminated body can also contain layers other than the said surface layer (A), an intermediate | middle layer (B), and an inner layer (C). For example, between the intermediate layer (B) and the inner layer (C), a gas barrier resin such as EVOH (ethylene-vinyl alcohol copolymer), or between the barrier resin and the intermediate layer (B) or the inner layer (C) An adhesive resin layer (for example, a layer made of polyolefin or the like graft-modified with an unsaturated compound such as maleic anhydride) for adhesion can also be provided. Further, a resin having little influence on the inner solution can be provided in the innermost layer, or the innermost surface can be processed such as coating. Furthermore, from the viewpoint of reducing the manufacturing cost of the molded product, a recycled layer using a recycled resin material obtained by pulverizing burrs generated during molding may be provided.
Moreover, in order to improve the melt fracture generated between the surface layer (A) and the intermediate layer and between the inner layer (B) and the intermediate layer, low-density polyethylene, high-density polyethylene, linear low-density polyethylene produced by a high-pressure method, A polypropylene layer may be introduced.

The thickness of the multilayer blow molded article (laminate) of the present invention is not necessarily limited, but the total thickness is preferably 0.1 to 2.5 mm, more preferably 0.3 to 1.5 mm. The thickness of the surface layer (A) of the multilayer blow molded product of the present invention is preferably 10 μm or more, more preferably 15 to 300 μm. When the thickness of the surface layer (A) is less than 10 μm, the layer is easily cut and the gloss is lowered.
The ratio of the thickness of each layer to the thickness of the entire multilayer blow molded article of the present invention is not particularly limited, but the ratio of the thickness of the surface layer (A) is 3 to 87%, and the ratio of the thickness of the intermediate layer (B). Is preferably 10 to 94%, and the thickness ratio of the inner layer (C) is preferably 3 to 87%. Further, the thickness ratio of the surface layer (A) is preferably 5 to 85%, the thickness ratio of the intermediate layer (B) is 15 to 90%, and the thickness ratio of the inner layer (C) is 5 to 85%. When the ratio of the thickness of the surface layer (A) or the inner layer (C) is less than 3%, partial defects of the surface layer (A) tend to occur, and the ratio of the thickness of the surface layer (A) and the inner layer (C) is 90%. When it exceeds%, it becomes easy to draw down. The surface layer (A) desirably has a layer thickness that accounts for 10 to 94% of the total thickness of the laminate. The intermediate layer (B) desirably has a layer thickness that occupies 15 to 90% of the total thickness of the laminate. The inner layer (C) preferably has a layer thickness that occupies 10 to 94% of the total thickness of the laminate.

  The surface of the multilayer blow molded article of the present invention is excellent in glossiness, and the gloss value measured at an incident angle of 60 ° in accordance with JIS-Z8741: 1997 is preferably 30% or more, and more preferably. Is 50% or more. If the gloss value is less than 30%, the glossy appearance is impaired.

  The total thickness portion of the body portion of the multilayer blow-molded article of the present invention preferably has a haze of 50% or less and a total light transmittance of 70% or more, more preferably, measured according to JIS-K7105: 1981. Has a haze of 40% or less and a total light transmittance of 80% or more. If the haze is out of the above range, the transparency tends to be inferior and the sense of quality is impaired.

  The multilayer blow molded product of the present invention, as described above, has a glossy and deep appearance, and is a high-quality plastic molding with excellent transparency, impact resistance, flexibility, rigidity, and environmental stress crack resistance. In addition to high gloss with a deep and uniform surface, it is excellent in flexibility, soft touch, touch, etc., excellent in physical properties such as handleability and drop impact strength, and deformed by external force applied to the container. In such a case, problems such as whitening do not occur. Therefore, it can be suitably used as a shampoo, rinse, cosmetics, medical container, food container such as edible oil, and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. In addition, the measuring method used in the Example is as follows.

(1) Melt flow rate (MFR) at a temperature of 190 ° C. and a load of 2.16 kg: measured in accordance with JIS K6922-2: 1997.
(2) Density: Measured according to JIS K6922-1 and 2: 1997.

(3) GPC: GPC measurement is based on the following method.
Use (i) Measurement Conditions c _o Tazu Inc. Model 150C, subjected to GPC measurement under the following conditions to determine the weight average molecular weight (Mw).
Column: Shodex HT-G (manufactured by Showa Denko KK) and HT-806M (manufactured by Showa Denko KK) x 2 Solvent: 1,2,4-trichlorobenzene Temperature: 140 ° C.
Flow rate: 1.0 ml / min Injection volume: 300 μl
(Ii) Sample preparation Approximately 3 mg of a sample and 3.0 ml of a solvent were weighed into a commercially available 4 ml screw top vial, and shaken at a temperature of 150 ° C. for 2 hours using an SSC-9300 type stirrer manufactured by Senshu Kagaku.
(Iii) Calculation of molecular weight GPC chromatographic data is loaded into a computer at a frequency of 1 point / second, processed according to the description in Chapter 4 of “Size Exclusion Chromatography” published by Sadao Mori and Kyoritsu Shuppan Co., Ltd. The value was calculated.
(Iv) Column calibration Monolithic polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S, manufactured by Showa Denko K.K.) -66.0, S-28.5, S-5.05), each 0.2 mg / l solution of n-eicosane and n-tetracontane, a series of monodisperse polystyrene measurements were taken and their A calibration curve was obtained by fitting the relationship between the elution peak time and the logarithm of molecular weight with a quartic polynomial.
In addition, the molecular weight of polystyrene was converted into the molecular weight of polyethylene using the following formula.
M _PE = 0.468 × M _PS

(4) Layer thickness: The cross section of the entire thickness portion of the molded container body was magnified 30 times with a stereomicroscope and the thickness of each layer was measured. The layer ratio is determined by measuring the thickness of the surface layer (A), the intermediate layer (B) and the inner layer (C), calculating the ratio of each layer to the total thickness, and forming the surface layer (A) and intermediate layer ( The thinning effect of B) was judged.
(5) Viscosity by Capillograph: Using a Capillograph 1B manufactured by Toyo Seiki Co., Ltd., a nozzle having a nozzle diameter of 1 mmφ was used and measured at a land length of 20 mm, an inflow angle of 90 °, a measurement temperature of 190 ° C., and a shear rate of 23 sec ⁻¹ .
(6) Glossiness: Measured at an incident angle of 60 ° in accordance with JIS Z8741: 1997.
(7) Haze: Measured according to JIS K7105: 1981.
(8) Total light transmittance: measured in accordance with JIS K7105: 1981.
(9) Parison temperature: The extruded resin was measured with a rod-shaped thermocouple thermometer.
(10) Surface roughness: The surface roughness of the mold cavity surface was measured according to JIS B0601: 1982.

(11) Container wall appearance: The appearance of the container which is a blow-molded product is evaluated visually, and its state is evaluated. “Glossy” indicates that there is no glossiness, “Inferior glossiness” indicates that there is no glossiness, and the surface layer (A) and intermediate layer (B) or intermediate layer (B) and inner layer (C) have gloss. The one where melt fracture occurred between them was called “scale pattern generation”.
(12) Pinch-off peeling: The peel of the parison fusion part (pinch-off) at the bottom of the molded container was visually determined. The case where there was no peeling was judged as “No”, and the case where peeling occurred was judged as “Yes”.
(13) Parison stickiness: The extruded parison is sandwiched between molds, and the parison outside the mold is cut with a cutter. At that time, it is judged visually whether the parison pulls the yarn or not, and the yarn is pulled. “None” was assigned to the one that did not exist, and “Yes” was assigned to the one that pulled the thread.
(14) Drawdown: When the parison length extruded from the die of the extruder reaches 60 cm, the value divided by the time to reach 12 cm is 2.5 or more, drawdown is “no”, and less than 2.5 is draw Down “Yes”.

1. Resin polyethylene (A-1) for surface layer (A) and inner layer (C)
Polyethylene obtained by using a metallocene catalyst and having an MFR of 0.7 g / 10 min, a density of 0.905 g / cm ³ , an Mw / Mn of 2.1, and a viscosity by a capillograph of 5000 Pa · sec was used.
Polyethylene (A-2)
Polyethylene obtained by using a metallocene catalyst and having an MFR of 1.0 g / 10 min, a density of 0.870 g / cm ³ , an Mw / Mn of 2.5, and a capirograph viscosity of 4050 Pa · sec was used.
Polyethylene (A-3)
Polyethylene obtained by using a metallocene catalyst and having an MFR of 4.0 g / 10 min, a density of 0.918 g / cm ³ , an Mw / Mn of 3.3, and a capirograph viscosity of 1600 Pa · sec was used.
Polyethylene (A-4)
A polyethylene obtained by using a metallocene catalyst and having an MFR of 15 g / 10 min, a density of 0.928 g / cm ³ , an Mw / Mn of 2.6, and a viscosity by capillograph of 500 Pa · sec was used.
Polyethylene (A-5)
A polyethylene obtained by using a metallocene catalyst and having an MFR of 20 g / 10 min, a density of 0.925 g / cm ³ , an Mw / Mn of 2.9, and a capirograph viscosity of 370 Pa · sec was used.

2. Intermediate layer (B) resin polyethylene (B-1)
A polyethylene obtained by using a Phillips catalyst and having an MFR of 0.3 g / 10 min, a density of 0.935 g / cm ³ , an Mw / Mn of 9, and a capillographic viscosity of 3800 Pa · sec was used.
Polyethylene (B-2)
Polyethylene obtained by using a Philips catalyst and having an MFR of 0.07 g / 10 min, a density of 0.952 g / cm ³ , an Mw / Mn of 10, and a viscosity by capillograph of 7000 Pa · sec was used.
Polyethylene (B-3)
A polyethylene obtained by using a Phillips catalyst and having an MFR of 0.15 g / 10 min, a density of 0.955 g / cm ³ , an Mw / Mn of 8, and a capillographic viscosity of 5800 Pa · sec was used.
Polyethylene (B-4)
Polyethylene obtained by using a Ziegler catalyst and having an MFR of 0.3 g / 10 min, a density of 0.935 g / cm ³ , an Mw / Mn of 25, and a viscosity by capillograph of 3850 Pa · sec was used.
Polyethylene (B-5)
A polyethylene obtained by using a Philips catalyst and having an MFR of 0.9 g / 10 min, a density of 0.947 g / cm ³ , an Mw / Mn of 10, and a viscosity by capillograph of 2400 Pa · sec was used.
Polyethylene (B-6)
A polyethylene obtained by using a Ziegler catalyst and having an MFR of 1.5 g / 10 min, a density of 0.967 g / cm ³ , an Mw / Mn of 6, and a capillographic viscosity of 1800 Pa · sec was used.
Polyethylene (B-7)
A polyethylene obtained by using a Ziegler catalyst and having an MFR of 4.0 g / 10 min, a density of 0.953 g / cm ³ , an Mw / Mn of 7, and a capirograph viscosity of 1120 Pa · sec was used.
Polyethylene (B-8)
A polyethylene obtained by using a Ziegler catalyst and having an MFR of 7.0 g / 10 min, a density of 0.967 g / cm ³ , an Mw / Mn of 16, and a viscosity by a capillograph of 950 Pa · sec was used.
Polyethylene (B-9)
Polyethylene produced by a high-pressure method having an MFR of 0.3 g / 10 min, a density of 0.930 g / cm ³ , an Mw / Mn of 5.6, and a caprolographic viscosity of 4200 Pa · sec was used.
Polyethylene (B-10)
Polyethylene produced by a high pressure method having an MFR of 0.7 g / 10 min, a density of 0.920 g / cm ³ , an Mw / Mn of 4.9, and a caprolographic viscosity of 2750 Pa · sec was used.
Polyethylene (B-11)
Polyethylene produced by a high pressure method having an MFR of 3.0 g / 10 min, a density of 0.910 g / cm ³ , an Mw / Mn of 3.5, and a capirograph viscosity of 1400 Pa · sec was used.

[Example 1]
The surface layer (A) resin screw diameter was 30 mmφ, the intermediate layer (B) resin screw diameter was 40 mmφ, and the inner layer (C) resin screw diameter was 50 mmφ in a three-layer head structure. Under the temperature setting, the screw rotation speed was adjusted to extrude the parison with the layer ratio of the surface layer (A), intermediate layer (B) and inner layer (C) extruded, and blow mold for 550 ml flat container (rough cavity surface) A mold having a Ra value of 0.4 μm), a mold temperature of 20 ° C., a blow pressure of 6 kg / cm ² , a bottle weight of 38 g (the thickness of the container body is 0.8 to 0.9 mm), and a molding cycle of 12 seconds. Blow molding was performed.
Polyethylene (A-1) is used as the resin for the surface layer (A), polyethylene (B-1) is used as the resin for the intermediate layer (B), polyethylene (A-2) is used as the resin for the inner layer (C), and the parison temperature is 218. Multi-layer blow molding was performed at 0 ° C. to obtain a hollow container. Various physical properties of the obtained container are shown in Table 1.

[Example 2] to [Example 14]
The procedure was the same as Example 1 except that the conditions in Table 1 were used. Various physical properties of the obtained container are shown in Table 1.

[Comparative Example 1] to [Comparative Example 10]
The procedure was the same as Example 1 except that the conditions in Table 1 were used. Various physical properties of the obtained container are shown in Table 1.

As is clear from the evaluation results in Table 1, in Examples 1 to 14, all have good appearance gloss, excellent transparency, no pinch-off peeling, and no parison stickiness. That is, in the examples, polyethylene of specific physical properties is adopted for the surface layer (A), the intermediate layer (B) and the inner layer (C) according to the present invention, so that in the multilayer blow molding so as to have a specific multilayer structure. It can be seen that when extruding a parison, a highly glossy surface can be produced and excellent transparency can be revealed, resulting in a container with a uniform glossy appearance with no unevenness.
On the other hand, it can be seen that the containers of Comparative Examples 1 to 10 have poor results in one or more performance evaluations of gloss appearance, appearance, transparency, pinch-off peeling, or parison tackiness. That is, in Comparative Examples 1 and 2, since the MFR of polyethylene (a) which is a resin of the surface layer (A) and the inner layer (C) is out of the scope of the present invention, the gloss and the surface glossiness of the molded product are inferior. ing. In Comparative Examples 3 and 4, since the MFR of polyethylene (c), which is the resin of the intermediate layer (B), is out of the scope of the present invention, the gloss of the appearance of the molded product is relatively good. Or pinch-off peeling is inferior. And since the comparative examples 5 and 6 did not use resin of a surface layer (A) and an inner layer (C), the glossiness and haze of a molded article external appearance are inferior. In Comparative Examples 7 and 8, since the MFR of polyethylene (b) which is the resin of the surface layer (A) is out of the range of the present invention, the gloss and haze of the molded product appearance are inferior. Further, in Comparative Examples 9 and 10, since the MFR of polyethylene which is the resin of the inner layer (C) is outside the scope of the present invention, the gloss of the appearance of the molded product is good, but the haze or pinch-off wall thickness is inferior. Yes.

  According to the present invention, a plastic blow-molded product having excellent surface glossiness, in particular, a high-grade that has excellent glossiness of the outer surface layer of the container, and excellent transparency, impact resistance, flexibility, and environmental stress crack resistance. It is possible to provide a multilayer blow-molded product that can be widely used as a sensitive hollow container, for example, a container for shampoo, rinse, cosmetics, medical use, and the like.

Claims (8)

A multilayer blow molded article formed by a laminate comprising the following surface layer (A), intermediate layer (B) and inner layer (C),
The surface layer (A) and the inner layer (C) have an MFR (temperature 190 ° C., load 2.16 kg) of 1.0 to 15 g / 10 min, a density of 0.870 to 0.928 g / cm ³ , and a gel A ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) measured by permeation chromatography (GPC) (Mw / Mn) is 1.5 to 4.0, and comprises polyethylene (a) produced with a metallocene catalyst,
The intermediate layer (B) has an MFR (temperature 190 ° C., load 2.16 kg) of 0.1 to 5 g / 10 min, a density of 0.910 to 0.967 g / cm ³ , and gel permeation chromatography. (GPC) Mw / Mn as measured from 3.3 to 28, consisting of a polyethylene produced by a Phillips catalyst or a Ziegler catalyst, or a polyethylene (b) produced by a high pressure method,
A multilayer blow-molded product characterized by that. The multilayer blow molded article according to claim 1, wherein the polyethylene (a) has a viscosity of 460 to 4200 Pa · sec measured at a temperature of 190 ° C and a shear rate of 23 sec ^-1 using a capillograph. The multilayer blow-molded product according to claim 1 or 2, wherein the polyethylene (b) has a viscosity of 1000 to 6000 Pa · sec measured at a temperature of 190 ° C and a shear rate of 23 sec ^-1 using a capillograph.   The multilayer blow molded article according to any one of claims 1 to 3, wherein the thickness of the surface layer (A) is 10 µm or more.   The thickness of the surface layer (A) is 3 to 87% with respect to the entire thickness of the laminate, and the thickness of the intermediate layer (B) is 10 to 94% with respect to the entire thickness of the laminate. The multilayer blow-molded product according to any one of claims 1 to 4, wherein the thickness is 3 to 87% with respect to the entire thickness of the laminate.   The multilayer blow-molded product according to any one of claims 1 to 5, wherein the surface of the molded product has a gloss value (incident angle of 60 °) of 30% or more.   The multilayer blow-molded product according to any one of claims 1 to 6, wherein the entire thickness portion of the molded product body has a haze of 50% or less and a total light transmittance of 70% or more. A method for producing a multilayer blow molded article formed by a laminate comprising a surface layer (A), an intermediate layer (B) and an inner layer (C),
The following polyethylene (a) is selected for the surface layer (A) and the inner layer (C), and the following polyethylene (b) is selected for the intermediate layer (B). After simultaneous melting, the parison is adjusted so that the surface temperature is 240 ° C. or less. A process for producing a multilayer blow-molded product, characterized by extruding and subsequently blow-molding.
Polyethylene (a): MFR (temperature 190 ° C., load 2.16 kg) is 1.0 to 15 g / 10 min, density is 0.870 to 0.928 g / cm ³ , and gel permeation chromatography (GPC) ) Polyethylene (b) produced with a metallocene catalyst having a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) of 1.5 to 4.0: MFR (temperature 190 ° C., load 2.16 kg) ) Is 0.1 to 5 g / 10 min, density is 0.910 to 0.967 g / cm ³ , and Mw / Mn by GPC measurement is 3.3 to 28. Polyethylene made by high pressure method