CN101903256A - High gloss multilayer plastic container - Google Patents

Abstract

A multilayer plastic container having, in order from the outer surface side, (1) a transparent plastic resin outer layer, (2) a transparent adhesive resin layer, and (3) a colored polyolefin resin layer, wherein the surface roughness of the transparent plastic resin outer layer is Ra of 0.2 [ mu ] m or less, the irregularities at the interface between the (1) transparent plastic resin outer layer and the (2) transparent adhesive resin layer are 15 [ mu ] m or less, and the irregularities at the interface between the (2) transparent adhesive resin layer and the (3) colored polyolefin resin layer are 15 [ mu ] m or less, is obtained. As the (1) transparent plastic resin outer layer, a transparent ethylene-vinyl alcohol copolymer resin is preferably used. According to the present invention, a multilayer plastic container having a uniform and smooth surface and a high gloss, deep color tone, and excellent appearance is obtained.

Description

High Gloss Multilayer Plastic Containers

technical field

The present invention relates to a multilayer plastic container having an excellent appearance and a deep surface with high gloss.

Background technique

Conventionally, multilayer plastic containers have been widely used as packaging containers for various contents such as cosmetics, hygiene products, various beverages, condiments, or foods.

In the above-mentioned multi-layer container, various plastic materials are used in combination in order to satisfy various characteristics required for storage of contents from the viewpoint of moldability and manufacturing cost. As the resin constituting the outer layer of the multilayer plastic container, polyester-based resins such as polyethylene terephthalate (PET), polyamide-based resins, and polyolefin-based resins such as polyethylene and polypropylene are generally used. wait. On the other hand, linear olefin-based resins such as polyethylene and polypropylene are often used for inner layers of containers in terms of moldability, hygienic properties, and cost.

In addition, in order to prevent oxygen from permeating the container wall, it has been known to provide an oxygen-barrier resin layer in a multilayer plastic container. As such a gas barrier resin, ethylene vinyl alcohol copolymer (ethylene-vinyl acetate copolymer saponified product), polyamide, polyvinylidene chloride-based resin, polyvinyl alcohol, fluororesin, etc. are used, for example.

Various technical proposals have also been made regarding the layer structure of a multilayer plastic container obtained by combining these resins. For example, there is known a multilayer plastic container having a layer structure in which (1) polyester resin, (2) adhesive resin and (3) polyolefin resin are laminated sequentially from the outer surface side of the container (for example, refer to Patent Documents 1, 2).

In addition, it is also known to laminate (1) polypropylene-based resin, (2) adhesive resin, (3) gas barrier resin, (4) adhesive resin, and (5) sequentially from the outer surface side of the container. A multilayer plastic container having a layer structure made of a polypropylene resin (for example, refer to Patent Documents 3 and 4).

[Patent Document 1] Japanese Patent Application Laid-Open No. 6-79842

[Patent Document 2] Japanese Patent Application Laid-Open No. 6-106606

[Patent Document 3] Japanese Patent Application Laid-Open No. 5-8355

[Patent Document 4] Japanese Patent Application Laid-Open No. 5-42641

However, in a multilayer plastic container having such a layer structure, the resins constituting the layers of the container differ in molding properties such as molten resin viscosity. Therefore, for example, when a hollow container is produced by blow molding after forming a multilayer parison, appearance defects such as a ripple pattern may occur on the outer resin layer on the surface of the container or between layers. In addition, the hue also becomes non-uniform, and there is a possibility that a hue defect such as a streaked pattern may occur. Therefore, a multilayer plastic container having an excellent appearance such as a high-gloss, deep, uniform metallic tone container cannot be realized.

Moreover, if the roughness of the inner surface of the mold is reduced in order to process the surface of the container smoothly, air pockets (due to air being entrapped between the mold and the surface of the molded product, leaving the part where the shape of the mold has not been transferred) will occur when the container is molded. Phenomenon). As a result, there was a problem of defective molding such as partial unevenness on the surface of the container.

Contents of the invention

Accordingly, an object of the present invention is to provide a multilayer plastic container having a uniform and smooth surface, a high-gloss, deep color tone, and an excellent appearance, eliminating the problems specific to such multilayer plastic containers.

The inventors of the present invention have found that by reducing the surface roughness of the plastic resin outer layer, the unevenness of the interface between the resin outer layer and the adhesive resin layer inside it is 15 μm or less, and the color polyolefin layer between the adhesive resin layer and the inner side is reduced. The unevenness of the resin layer interface is 15 μm or less, and the above-mentioned problems can be solved, and the present invention has been completed.

That is, in the present invention, the following items 1 to 9 are employed.

1. A high-gloss multilayer plastic container, which is a multilayer plastic having (1) a transparent plastic resin outer layer, (2) a transparent adhesive resin layer, and (3) a colored polyolefin resin layer in this order from the outer surface side The container is characterized in that the surface roughness of the transparent plastic resin outer layer is Ra≤0.2 μm, the unevenness of the interface between the above (1) transparent plastic resin outer layer and the above (2) transparent adhesive resin layer is 15 μm or less, and the above ( 2) The unevenness of the interface between the transparent adhesive resin layer and the above (3) colored polyolefin resin layer is 15 μm or less.

2. The high-gloss multilayer plastic container described in 1 above, wherein the transparent plastic resin (1) above contains a transparent ethylene-vinyl alcohol copolymer resin.

3. The high-gloss multilayer plastic container according to the above 1 or 2, wherein the colored polyolefin resin layer (3) above contains a glittering pigment.

4. The high-gloss multilayer plastic container according to any one of 1 to 3 above, wherein the colored polyolefin resin layer in (3) above contains a block polypropylene resin.

5. The high-gloss multilayer plastic container according to any one of 1 to 3 above, wherein the colored polyolefin resin layer in (3) above contains a high-density polyethylene resin.

6. The high-gloss multilayer plastic container described in any one of 1 to 4 above is characterized in that the layer structure of the multilayer plastic container has (1) transparent ethylene-vinyl alcohol copolymers in order from the outer surface side Resin outer layer, (2) transparent polypropylene-based adhesive resin layer, (3) colored polypropylene-based resin layer containing glitter pigment, (4) polypropylene-based resin layer not containing glitter pigment.

7. The high-gloss multilayer plastic container described in any one of the above 1 to 3 or 5 is characterized in that the layer structure of the multilayer plastic container has (1) transparent ethylene-vinyl alcohol copolymers in order from the outer surface side. Cluster resin outer layer, (2) transparent polyethylene-based adhesive resin layer, (3) colored polyethylene-based resin layer containing glitter pigment, (4) polyethylene-based resin layer not containing glitter pigment.

8. The high-gloss multilayer plastic container according to any one of 1 to 7 above, wherein the multilayer plastic container further has a polyolefin resin inner layer.

9. The high-gloss multilayer plastic container according to any one of 1 to 8 above, wherein the total thickness of the above (1) transparent plastic resin outer layer and the above (2) transparent adhesive resin layer is 30 to 200 μm.

According to the present invention, it is possible to efficiently obtain a multilayer plastic container having a smooth surface without appearance defects such as ripple patterns and foaming, and a high-gloss, deep, and uniform metallic tone without causing molding defects.

Description of drawings

[ Fig. 1 ] is a schematic cross-sectional view showing an example of the layer structure of the high-gloss multilayer plastic container of the present invention.

Symbol Description

A Transparent ethylene-vinyl alcohol copolymer resin outer layer

B transparent bonding resin layer

C Colored polyolefin resin layer containing glitter pigment

D Polyolefin resin layer without glitter pigment

Detailed ways

In the present invention, the layer structure of the multilayer plastic container has (1) a transparent plastic resin outer layer, (2) a transparent adhesive resin layer and (3) a colored polyolefin resin layer in order from the outer surface side. In addition, the surface roughness of the transparent plastic resin outer layer is Ra≤0.2 μm. Further, it is characterized in that by adopting technical means such as adjusting the shear stress of each resin constituting the container, the unevenness of the interface between (1) the transparent plastic resin outer layer and (2) the transparent adhesive resin layer is 15 μm or less, In addition, the unevenness at the interface between (2) the transparent adhesive resin layer and (3) the colored polyolefin resin layer is 15 μm or less.

However, the terms used in the present invention are defined as follows.

(Container surface roughness Ra)

In the present invention, (1) the surface roughness Ra of the outer layer of the transparent plastic resin refers to a measurement length of 4 mm for each flat portion of the container wall other than the nozzle portion using a stylus type roughness shape measuring instrument in accordance with JISB0601. The surface roughness (Ra) obtained by arithmetic mean is measured.

(Concavity and convexity of resin layer interface)

When measuring (1) the unevenness at the interface between the transparent plastic resin outer layer and (2) the transparent adhesive resin layer, and the unevenness at the interface between (2) the transparent adhesive resin layer and (3) the colored polyolefin resin layer, the For the flat part of the container wall other than the flat part, the part with large interface unevenness is taken as a sample. Then, using a rotary microtome, the container cross section of the obtained sample was cut as an observation surface. Furthermore, the sample was cut parallel to the observation surface with a thickness of 30 μm in the direction perpendicular to the observation surface as a sample, and the maximum value of the unevenness obtained by observing and measuring the observation surface with an optical microscope was regarded as the unevenness of the resin layer interface.

(Thickness of outer layer + transparent adhesive resin layer)

When measuring the total thickness of (1) the transparent plastic resin outer layer and (2) the transparent adhesive resin layer, the container obtained from the flat part of the container wall other than the nozzle part is manufactured in the same way as the unevenness of the above-mentioned resin layer interface. The section in the vertical direction of the side wall is used as the sample of the observation surface. Then, the observation surface was observed with an optical microscope, and the thicknesses of (1) the transparent plastic resin outer layer and (2) the transparent adhesive resin layer were measured.

Examples of preferable transparent plastic resins constituting the outer layer of the multilayer plastic container include ethylene-vinyl alcohol copolymer resins.

The ethylene-vinyl alcohol copolymer resin (EVOH) is not particularly limited as long as it has the transparency required to constitute the outer layer of the container. Preferred ethylene-vinyl alcohol copolymer resins include saponified ethylene-vinyl acetate copolymers having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%.

Examples of other resins constituting the outer layer of the multilayer plastic container include polyamide resins, polycarbonate resins, ionomer resins, and the like.

In addition, (1) The plastic resin outer layer may be uncolored or colored as long as it is transparent. However, it is preferable to avoid adding a pigment or the like that increases the surface roughness of the plastic resin.

In addition, (1) known additives may be added to the plastic resin outer layer to the extent that the transparency is not impaired. For example, thermoplastic elastomers, other thermoplastic resins, rubber resins, inorganic fillers, pigments, plasticizers, antioxidants, antistatic agents, light stabilizers, antiblocking agents, lubricants, dyes, etc. can be added.

Hereinafter, the multilayer plastic container of the present invention will be further described by taking the case of using EVOH as (1) the transparent plastic resin outer layer as an example.

In order to make (1) the surface roughness of the transparent plastic resin outer layer Ra ≤ 0.2 μm, a blow mold with a surface roughness of the inner surface of the blow mold of about 0.2 μm ≤ Ra ≤ 0.8 μm is used. By using the mold treated in this way, it is possible to obtain a container having a maximum surface roughness of Ra≦0.2 μm on the outer layer of the container. If the surface roughness Ra of the container exceeds 0.2 μm, the reflected light on the container surface will be disturbed, and the gloss will decrease in appearance.

If the surface roughness of the inner surface of the blow mold is reduced, air pockets will be formed during the molding of the plastic container, and molding failures such as partial surface unevenness may occur. In addition, if (1) the unevenness of the interface between the transparent EVOH and (2) the transparent adhesive resin layer inside, or (2) the unevenness of the interface between the transparent adhesive resin layer and the inner (3) colored polyolefin resin layer increases, Then, the hue becomes non-uniform, and there is a possibility that a hue defect such as a stripe pattern may occur.

In the present invention, by adopting technical means such as adjusting the water content of transparent EVOH to be below 5000ppm, preferably about 500-2500ppm, and adjusting the shear stress of each resin constituting the container, the maximum unevenness of the above-mentioned resin layer interface It is 15μm or less to prevent such poor molding problems. When the moisture content of the transparent EVOH exceeds 5000 ppm, foaming occurs during molding of the container.

EVOH has low adhesion to polyolefin resins, and there are differences in molding characteristics such as melt viscosity. Therefore, if a multilayer plastic container is formed with EVOH as the outer layer and polyolefin resin as the inner layer, appearance defects such as ripple patterns may occur on the EVOH outer layer on the container surface or at the interface of each layer.

The ripple pattern is generated at the interface between (1) the transparent EVOH outer layer and (2) the transparent adhesive resin layer inside, or (2) the interface between the transparent adhesive resin layer and (3) the colored polyolefin resin layer concave-convex pattern. When viewed from the surface of the side wall of the container, the concavo-convexity can be seen as scales formed continuously in the circumferential direction of the container. When the cross-section of the side wall of the multilayer plastic container is observed, the resin of the layer on the inner surface side protrudes in waves in the resin of the layer on the outer surface side at the interface where unevenness occurs. The irregularities can be observed well from the height direction cross-section of the side wall of the container, and most of them are irregularities with a width of several hundred μm and a thickness of the convex part of 15 to 50 μm. The cause of the unevenness is not clear, but it is considered to be caused by non-uniform resin flow in the molten resin confluence portion during the manufacture of the multilayer parison.

In the present invention, by adjusting the shear stress of each layer of resin constituting the multilayer plastic container and the melt flow rate (MFR) of the resin constituting the transparent adhesive resin layer, the balance between the EVOH outer layer and the polyolefin resin layer is compensated. difference in molding properties. Therefore, it is possible to reduce irregularities in the interface between (1) the transparent EVOH outer layer and (2) the transparent adhesive resin layer inside, and (2) the interface between the transparent adhesive resin layer and (3) the colored polyolefin resin layer inside Thus, a multilayer plastic container having excellent appearance, prevention of peeling between resin layers, etc., and excellent properties such as impact resistance can be obtained.

As the transparent adhesive resin, known resins having adhesiveness to both EVOH and polyolefin resins can be used. For example, ethylene·α-olefin copolymer resins and their acid-modified resins, olefin-acid copolymer resins, glycidyl group-containing resins, and the like can be used. Moreover, in order to improve adhesiveness, you may add a well-known tackifier to these resins.

As the copolymer, a copolymer prepared in an arbitrary bonding system such as random, block, or graft can be used. As the acid-modified resin, for example, resins graft-modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and crotonic acid, or their anhydrides are used. When an acid-modified resin is used as the adhesive resin, the hydroxyl group of EVOH is chemically bonded to the acid group of the acid-modified resin, and the adhesiveness between the outer layer and the adhesive resin layer is improved, so it is preferable. These resins may be used alone, as a mixed resin of two or more types, or as a mixed resin with other resins. Examples of the tackifier include rosin-based resins, terpene-based resins, petroleum resins, and the like. These resins can be used individually or in mixture of 2 or more types. As the binder resin, an acid-modified polyolefin resin is particularly preferable.

In addition, known additives may be added to the transparent adhesive resin layer. For example, thermoplastic elastomers, other thermoplastic resins, rubber resins, inorganic fillers, pigments, plasticizers, antioxidants, antistatic agents, light stabilizers, antiblocking agents and the like can be added.

In addition, as long as the transparent adhesive layer resin is transparent, it may be uncolored or colored, and may contain a glittering pigment. When the adhesive resin layer is colored, for example, by adding a glittering pigment to the colored polyolefin layer, the light reflected by the glittering pigment is transmitted through the transparent colored adhesive layer to obtain a deep and unique metallic feeling, which is preferable. In addition, by changing the color tone of the transparent adhesive layer and the polyolefin layer, it is sometimes possible to obtain a special hue effect. The coloring agent used for the transparent adhesive resin layer is not particularly limited as long as it does not impair transparency. As such a colorant, organic pigments such as azo-based pigments, phthalocyanine-based pigments, condensed polycyclic pigments, and dyed lake-based pigments can be used, for example.

(1) The unevenness of the interface between the transparent EVOH outer layer and (2) the transparent adhesive resin layer inside, and the unevenness of the interface between the (2) transparent adhesive resin layer and the inner (3) colored polyolefin resin layer can be obtained by The reduction is achieved by adjusting the resins constituting each layer of the multilayer plastic container so as to satisfy both the following (a) and (b).

(a) The shear stress (unit: KPa) of the resin constituting each layer satisfies "(3) colored polyolefin resin-55≦(2) transparent adhesive resin≦(1) transparent EVOH+70".

Among them, the shear stress of the resin refers to the temperature of the resin used under the conditions of 210°C, shear rate of 50/second, hole of the resin extrusion part of L = 10 mm, and D = diameter of 1 mm according to JIS K7199. The value obtained by measuring the particles before melting.

When the shear stress of the transparent adhesive layer resin is lower than "(3) Colored polyolefin resin-55", uneven irregular ripple patterns at the interface between the transparent adhesive resin layer and the colored polyolefin resin layer occur. On the other hand, when the shear stress of the transparent adhesive resin layer exceeds "(1) Transparent EVOH+70", a ripple pattern of irregularities in the interface between the transparent plastic resin layer and the transparent adhesive resin layer occurs.

(b) The melt flow rate (MFR) (g/10 min) of the resin constituting the transparent adhesive resin layer satisfies "1.0≦MFR≦2.5".

Here, the melt flow rate of the resin refers to a value obtained by measuring pellets of the resin used before melting at a temperature of 190° C. and a load of 2.16 Kg in accordance with JIS K7210.

When the MFR of the transparent adhesive layer resin is less than 1.0 (g/10 min), a ripple pattern of irregularities in the interface between the transparent EVOH layer and the transparent adhesive resin layer occurs. On the other hand, when the MFR of the transparent adhesive layer resin exceeds 2.5, a ripple pattern of irregularities in the interface between the transparent adhesive resin layer and the colored polyolefin resin layer occurs.

In the multilayer plastic container of the present invention, the total thickness of (1) the transparent plastic resin outer layer and (2) the transparent adhesive resin layer is preferably about 30 to 200 μm, particularly preferably about 60 to 150 μm.

If the thickness is less than 30 μm, the surface of the container becomes rough during molding, the surface gloss is poor, and the outer layer of the plastic resin is broken during molding. Moreover, when this thickness exceeds 200 micrometers, a transparent film will become too thick and become cloudy, and there exists a possibility that transparency may fall.

Furthermore, by making the total thickness of the transparent plastic resin outer layer and the transparent adhesive resin layer within this range, since the reflected light from the colored polyolefin resin layer on the inner layer side is subtly refracted, the depth of hue or gloss appears. . In addition, in order to obtain a desired surface roughness by mixing glittering pigments into a colored polyolefin resin layer to produce a metallic-colored container, it is preferable to separate (1) the transparent plastic resin outer layer and (2) the transparent adhesive resin layer. The total thickness is greater than the long diameter of the pigment.

The resin constituting the (3) colored polyolefin-based resin layer which is the inner layer of the (2) transparent adhesive resin layer is not particularly limited. For example, known low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate copolymer, and ethylenically unsaturated carboxylic acid can be used. Any of polyolefin-based resins such as polyolefin resins graft-modified with acids or their anhydrides. A propylene-ethylene block copolymer is mentioned as a particularly preferable polyolefin resin. These polyolefin resins can be used individually or in mixture of 2 or more types. In addition, it can also be used by mixing reflow products (recycled materials) generated during container molding, etc.

The colored polyolefin resin layer may be either a transparent colored layer or an opaque colored layer. In addition, not only one colored layer but two or more colored layers may be used. In addition, an intermediate layer made of other resin or the like, or an inner surface resin layer made of, for example, polyolefin resin constituting the inner surface of the container may be further provided on the inner layer side of the colored polyolefin resin layer.

The coloring agent compounded in (3) the colored polyolefin resin layer is not particularly limited, and organic pigments such as azo pigments, phthalocyanine pigments, condensed polycyclic pigments, and dyed lake pigments, or polarizing pigments can be used. Alumina-based glittering pigments such as pearlescent pigments, mica-based glittering pigments, glass-based glittering pigments, and other glittering pigments. These colorants can be used alone or in combination of two or more. In addition, these colorants can also be used in combination with extender pigments and the like.

When (3) a colored polyolefin resin layer is blended with a glittering pigment, the reflected light of the glittering pigment passes through a layer composed of (1) a transparent plastic resin outer layer and (2) a transparent adhesive resin layer, thereby obtaining a A multi-layered plastic container of a metallic tone with a deep luster.

In particular, the (3) colored polyolefin resin layer is formed as a multilayer composed of a transparent colored resin layer adjacent to the (2) transparent adhesive resin layer and a colored resin layer containing a glitter pigment provided on the inner side thereof. In the structure, it is preferable to obtain a unique metallic feeling with depth as if transparent ink is printed on a metal base.

[Example]

Next, the high-gloss multilayer plastic container of the present invention will be described by way of examples, but the present invention is not limited to the following specific examples.

Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the multilayer plastic container of the present invention. The container has (1) a transparent plastic resin (EVOH) outer layer A, (2) a transparent adhesive resin layer B, (3) a colored polyolefin resin layer C containing a glitter pigment, and (4) in order from the outer surface side. ) The polyolefin-based resin layer D not containing a glitter pigment. (2) The transparent adhesive resin layer B can be made into a transparent colored adhesive resin layer by adding a coloring pigment etc. within the range which does not impair transparency.

In the following examples, containers having the layer structure shown in FIG. 1 were produced as follows. In four extruders (hereinafter, the extruders constituting the resins of the resin layers A, B, C, and D are respectively referred to as extruder A, extruder B, extruder C, and extruder D) Resin is filled separately. Each resin is plasticized, kneaded and extruded while heating, and a multilayer head is used to form (1) transparent EVOH outer layer A, (2) transparent colored adhesive resin layer in order from the outer surface side B. A multilayer parison of (3) colored polyolefin resin layer C containing a glitter pigment and (4) polyolefin resin layer D not containing a glitter pigment. Then, the parison was sandwiched between a mold having a cavity, compressed air was blown to the parison, and a square tube-shaped hollow container with a capacity of 500 mL was produced. The inner surface roughness of the mold used was Ra=0.6 μm.

In the following examples, each physical property value was measured by the method already described. In addition, the moisture content of the transparent EVOH was measured on the pellets before melting by the Karl Fischer moisture measurement method. For measurement of each physical property value, "Surfcom 1400A-3DF-12 manufactured by Tokyo Seiki Kogyo" was used as a stylus type roughness profile measuring instrument. For the rotary microtome, "RM2125RT for inspection manufactured by Laika", "Measuring Microscope STM5-321 manufactured by Olympus" was used for the optical microscope, and "Ciyapirograph 1D manufactured by Tokyo Seiki Seisakusho" was used for the resin shear stress measuring instrument.

In addition, the surface roughness Ra of the multilayer plastic container was measured by directly or cutting out a portion having a large surface roughness obtained from a flat portion other than the nozzle portion of the container to a size of 15 mm×15 mm. In addition, the "thickness of the outer layer+transparent adhesive resin layer" was measured at 8 points at intervals of 45° in the circumferential direction on the upper, middle, and lower portions of the trunk of the container, and the average value thereof was adopted. Furthermore, the evaluation of the gloss of the container was carried out by visually observing all the flat parts of the container other than the nozzle.

(Example 1)

A transparent ethylene-vinyl alcohol copolymer resin (EVOH) having a shear stress of 100 (KPa) and a moisture content of 1500 ppm was filled into an extruder A having a diameter of 40 mm. In an extruder B with a bore diameter of 40 mm, a transparent and colorless acid-modified polypropylene resin with a MFR of 1.6 (g/10 min) and a shear stress of 100 (KPa) and 0.3% by weight of a colored pigment were filled. Nitrogenous red pigments. In the extruder C with a diameter of 50mm, the transparent and colorless ethylene-propylene block copolymer resin with a MFR of 0.8 (g/10min) and a shear stress of 120 (KPa) and 1.0% by weight of pearls as a glittering pigment were filled. Red (mica-based pigment with an average particle diameter of 21 μm), and 0.3% by weight of an azo-based red pigment as a coloring pigment. The above-mentioned transparent and colorless ethylene-propylene block copolymer resin was filled into an extruder D with a caliber of 40 mm. The resin filled in each extruder is plasticized and kneaded while being heated, and extruded from a multi-layer head to form a multi-layer parison. Then, the parison was sandwiched by a mold having a cavity, and compressed air was blown to the parison to obtain a square cylindrical hollow bottle with a capacity of 500 mL.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.11 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 6 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.11 μm. The unevenness of the interface between them was 7 μm, and the surface gloss of the bottle was good.

(Example 2)

In Example 1, the same hollow bottle was obtained as in Example 1 except that EVOH having a shear stress of 60 (KPa) and a moisture content of 1200 ppm was used as the outer layer resin A.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.18 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 15 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.18 μm. The unevenness of the interface between them was 8 μm, and the surface gloss of the bottle was good.

(Example 3)

In Example 2, a transparent and colorless acid-modified polypropylene resin with an MFR of 2.5 (g/10min) and a shear stress of 65 (KPa) was used as the transparent colored adhesive resin B. Example 2 obtained the same hollow bottle in the same way.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.12 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 7 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.12 μm. The unevenness of the interface between them was 15 μm, and the surface gloss of the bottle was good.

(Example 4)

In Example 1, a transparent and colorless acid-modified polyethylene resin having an MFR of 1.4 (g/10 min) and a shear stress of 110 (KPa) was used as the transparent colored adhesive resin B. Furthermore, as the transparent and colorless resins of the glitter-colored polyolefin resin C and the transparent polyolefin resin D, a high-density polyethylene resin having an MFR of 0.36 (g/10 min) and a shear stress of 120 (KPa) was used. Other conditions were the same as in Example 1 to obtain the same hollow bottle.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.12 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 6 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.12 μm. The unevenness of the interface between them was 8 μm, and the surface gloss of the bottle was good.

(Example 5)

In Example 1, EVOH with a shear stress of 70 (KPa) and a water content of 1500 ppm was used as the outer layer resin A, and an MFR of 1.0 (g/10min) and a shear stress of 120 (KPa) were used as the transparent colored resin B. ) was transparent and colorless acid-modified polypropylene resin, and the same hollow bottle was obtained in the same manner as in Example 1.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.20 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 15 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.20 μm. The unevenness of the interface between them was 7 μm, and the surface gloss of the bottle was good.

(Example 6)

In Example 1, the same hollow bottle was obtained as in Example 1 except that the discharge rates of the extruders A and B were changed.

The thickness of each layer of this bottle was 13 μm for the outer layer A, 17 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.12 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 7 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.12 μm. The unevenness of the interface between them was 8 μm, and the surface gloss of the bottle was good.

(Example 7)

In Example 1, the same hollow bottle was obtained as in Example 1 except that the discharge rates of the extruders A and B were changed.

The thickness of each layer of this bottle was 85 μm for the outer layer A, 115 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.11 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 5 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.11 μm. The unevenness of the interface between them was 6 μm, and the surface gloss of the bottle was good.

(comparative example 1)

In Example 1, the same hollow bottle was obtained as in Example 1 except that EVOH having a shear stress of 30 (KPa) and a water content of 1600 ppm was used as the outer layer resin A.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.22 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 18 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.22 μm. The unevenness of the interface between them was 7 μm, and a ripple pattern was generated between the EVOH outer layer A and the transparent colored adhesive resin layer B.

(comparative example 2)

In Example 1, a transparent and colorless acid-modified polypropylene resin having an MFR of 3.5 (g/10min) and a shear stress of 48 (KPa) was used as the transparent colored adhesive resin B. Example 1 obtained the same hollow bottle in the same way.

The thickness of each layer of this bottle was 50 μm for the outer layer A, 70 μm for the transparent colored adhesive resin layer B, 710 μm for the glitter colored polyolefin resin layer C, and 170 μm for the transparent polyolefin resin layer D. In addition, the surface roughness Ra of the bottle was 0.12 μm, the unevenness of the interface between the transparent EVOH outer layer A and the transparent colored adhesive resin layer B was 7 μm, and the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C was 0.12 μm. The unevenness of the interface between them was 17 μm, and a ripple pattern was generated at the interface between the transparent colored adhesive resin layer B and the glitter colored polyolefin resin layer C.

This international application claims priority to Japanese Patent Application No. 2007-325397 filed on December 18, 2007, and the entire contents of Japanese Patent Application No. 2007-325397 are incorporated herein by reference.

Claims (9)

1. A high-gloss multilayer plastic container, which is a multilayer plastic having (1) a transparent plastic resin outer layer, (2) a transparent adhesive resin layer, and (3) a colored polyolefin resin layer in this order from the outer surface side The container is characterized in that the surface roughness of the transparent plastic resin outer layer is Ra≤0.2 μm, the unevenness of the interface between the (1) transparent plastic resin outer layer and the (2) transparent adhesive resin layer is 15 μm or less, and The unevenness of the interface between the (2) transparent adhesive resin layer and the (3) colored polyolefin resin layer is 15 μm or less. 2. The high-gloss multi-layer plastic container according to claim 1, wherein said (1) transparent plastic resin comprises a transparent ethylene-vinyl alcohol copolymer resin. 3. The high-gloss multilayer plastic container according to claim 1 or 2, wherein the (3) colored polyolefin resin layer contains a glittering pigment. 4. The high-gloss multilayer plastic container according to any one of claims 1 to 3, wherein the (3) colored polyolefin resin layer contains a block polypropylene resin. 5. The high-gloss multilayer plastic container according to any one of claims 1 to 3, wherein the (3) colored polyolefin resin layer contains a high-density polyethylene resin. 6. The high-gloss multilayer plastic container according to any one of claims 1 to 4, wherein the layer structure of the multilayer plastic container has (1) transparent ethylene-vinyl alcohol successively from the outer surface side Copolymer resin outer layer, (2) transparent polypropylene adhesive resin layer, (3) colored polypropylene resin layer containing glitter pigment, (4) polypropylene resin layer not containing glitter pigment. 7. The high-gloss multilayer plastic container according to any one of claims 1 to 3 or 5, wherein the layer structure of the multilayer plastic container has (1) transparent vinyl- Vinyl alcohol copolymer resin outer layer, (2) transparent polyethylene adhesive resin layer, (3) colored polyethylene resin layer containing glitter pigment, (4) polyethylene resin layer not containing glitter pigment. 8. The high-gloss multilayer plastic container according to any one of claims 1 to 7, wherein the multilayer plastic container further has a polyolefin resin inner layer. 9. The high-gloss multilayer plastic container according to any one of claims 1 to 8, wherein the total thickness of the (1) transparent plastic resin outer layer and the (2) transparent adhesive resin layer 30-200 μm.

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