JPH04303619A - Plastic multilayer blow-molded container - Google Patents

Abstract

PURPOSE:To provide a plastic multilayer blow-molded container, which is excellent in transparency, the outer surface gloss of which is low and which is full of high-class impression. CONSTITUTION:A plastic multilayer blow-molded container consisting of inner layer 2 and outer layer 1, the thickness of which is 1.0-10.0% of the total thickness and which contains 1.0-50wt.% of filler having the particle diameter of 1.0-15.0mum and the refractive index of 1.44-1.60, is provided. The blow molding is performed with a mold having mirror-finished cavity surface.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to plastic multilayer blow containers. More specifically, the present invention relates to a plastic multilayer blow container with excellent transparency and low surface gloss.

0002

BACKGROUND OF THE INVENTION Conventionally, in order to release air between the blow mold and the parison which is expanded into a container shape by compressed air, a blow mold has been used in which the inner surface of the cavity is roughened by sandblasting. For this reason, the outer surface of the blow container has a rough surface reflecting the irregularities of the mold, and while the gloss is low, light is diffusely reflected and the transparency is poor.

[0003] On the other hand, there is also known a method of manufacturing a blow container with an excellent outer surface gloss by blow molding using a mirror-polished mold. In this method, various techniques are used to release air between the mold and the parison. For example, a highly concentrated filler is mixed into the parison.
This is a method of letting air escape by making the surface of the parison extruded from an extruder uneven.
Publication No. 2031).

[0004] Furthermore, a method of providing vacuum suction holes in a mirror-like mold and performing vacuum suction at the same time as compressed air blowing (Japanese Patent Application No. 3-14426) was previously filed for a patent by the applicant. has been done.

[0005] According to these methods, a blow container with excellent transparency can be manufactured, but it has not been possible to obtain a blow container with low surface gloss.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a plastic multilayer blow container that has excellent transparency, low surface gloss, and a high-quality feel.

[0007]

To achieve this object, the invention as claimed in claim 1 provides a plastic multilayer blow container comprising an outer layer and an inner layer, wherein the outer layer has a total thickness of 1.0 to 10. This outer layer has a particle size of 1.0%.
A plastic multilayer blow container is provided, characterized in that it is made of plastic containing 1.0 to 50% by weight of a filler having a diameter of 15.0 μm and a refractive index of 1.44 to 1.60.

[0008] Furthermore, the invention according to claim 2 is characterized in that the inner layer is composed of a layer containing regrind plastic, or a multilayer structure of a layer containing regrind plastic and another plastic layer. Provide a container.

The present invention will be explained below with reference to the drawings. FIG. 1 of the drawings is a partially sectional view showing the layer structure of an embodiment of the plastic multilayer blow container according to the present invention. Further, FIG. 2 is a cross-sectional view showing the layer structure of another embodiment. FIG. 3 is a perspective view of a mold for molding a container according to the present invention. Moreover, FIG. 4 is an explanatory diagram of air suction means for molding.

As shown in FIGS. 1 and 2, the container of the present invention has a multilayer structure consisting of an outer layer 1 and an inner layer 2. The inner layer 2 may be a single layer as shown in FIG. 1, or may be a two-layer structure consisting of 2a and 2b as shown in FIG.

[0011] The outer layer 1 determines the gloss of the outer surface of the container, and therefore contains a high concentration of powdered filler, which causes fine irregularities on the outer surface. 1.0-5
It is necessary to contain 0.0% by weight. In order to produce fine irregularities, the filler needs to have a particle size of 0.5 to 15.0 μm. If it is less than 0.5 μm, good unevenness cannot be formed, and if it exceeds 15.0, the unevenness is too large.

[0012] Furthermore, in order to form sufficient irregularities, the filler must be contained in an amount of 1.0 to 50.0% by weight of the entire outer layer 1. If it is less than 1.0% by weight, the unevenness will be insufficient;
If it is 0% by weight or more, molding is difficult.

[0013] The presence of the filler must not impair the transparency of the container. Therefore, the filler has a refractive index of 1.4
4 to 1.60 should be used. By using a filler with a refractive index of this level, the container will have sufficient transparency to allow the contents to be seen through, and will also have a light color with no gloss.

[0014] The thickness of the entire container is usually 500 to 1000μ.
m, and the outer layer 1 should account for 1.0 to 10.0% of it. This is because if it is thicker than this, transparency may be impaired.

[0015] As such a filler, particles with a particle size of 0
．． Examples include synthetic silica and magnesium carbonate with a diameter of 5 to 15.0 μm.

Any transparent plastic can be used as the plastic for the outer layer 1. However, since it affects the appearance of the container, it is preferable to use virgin plastic that is not regrind (plastic that is recycled by melting plastic that has been molded). For example, polyolefins such as polyethylene, polypropylene, and copolymers of ethylene and α-olefin can be used.

The plastic of the inner layer 2 has good adhesion to the outer layer 1, and is preferably transparent. As shown in Figure 1,
When the inner layer 2 consists of a single layer, polyolefin or a resin obtained by modifying polyolefin with an unsaturated carboxylic acid can be used. Further, it may be regrind plastic or a mixture of regrind plastic and virgin plastic.

However, when using regrind plastic, as shown in FIG. 2, the inner layer 2 has a multilayer structure, the innermost layer 2b is virgin plastic, and the outer layer 1
and the innermost layer 2b is a regrind plastic layer 2a.
It is desirable to do so. This is because regrind plastic often contains impurities and is not suitable for the innermost layer 2b that comes into contact with contents such as foods and cosmetics.

The container of the present invention can be obtained by manufacturing a multilayer parison by a well-known multilayer coextrusion method and then blow molding the parison using a mirror-like mold.

FIG. 3 shows this mold 10, in which a cavity is formed when the mold is clamped with another mold. The other molds are similar to mold 10.

The mold 10 is made of aluminum or carbon steel, for example, and the parting surface 10a where the mold 10 and another mold come into close contact has a recess 12 that forms a cavity when the mold is clamped.
is formed. The center line average roughness of the inner surface of the recess 12 is 0.25 μm or less, which is a so-called mirror surface.

Vacuum suction recesses 13 and 14 are formed in the parting surface 10a so as to surround the recess 12. The suction recesses 13 and 14 form air suction holes 15a and 15b when the molds 10 and 20 are clamped. Communication holes 16a and 16b communicating with the outside of the mold 10 are opened at the bottoms of the suction recesses 13 and 14. This communication hole 16a,
Air suction means 20 arranged outside the mold 10 is connected to 16b. A shallow groove is formed between the suction recesses 13 and 14 and the cavity forming recess 12,
When the mold 10 is clamped, this groove serves as an air suction hole 15a,
15b, which sucks air from the cavity during mold clamping. The grooves 13a and 14a have such a depth that the parison, which expands when compressed air is blown into the parison, does not enter.

Furthermore, air suction holes 17a and 17b are opened in the side wall at the lower end of the cavity forming recess 12. Plugs 18 made of sintered metal are fitted into the openings of the air suction holes 17a and 17b on the cavity side, so that the air in the cavity 11 can be sucked through the plugs 18.

The air suction means 20, as shown in FIG.
Vacuum pump 21, chamber 22 for vacuum reservoir, and tube 2
3a, 23b, and valves 24a, 24b. The vacuum pump 21 is connected to the chamber 22 via a pipe 23a, and the chamber 22 is connected to the communication hole 1 via a pipe 23b.
6a, 16b and air suction holes 17a, 17b. Valve 24a is provided in pipe 23a, and valve 24a is provided in pipe 23a.
4b is provided in the tube 23b.

A multilayer parison produced by the well-known multilayer coextrusion method is housed in a cavity consisting of mold 10 and another mold, and the bottom of the parison is fused. Further, a blow pin for blowing compressed air is inserted into the opening of the parison.

In parallel with this, or separately from this, the valve 23a is opened and the air inside the chamber 22 is vacuum-sucked by the vacuum pump 21 to maintain the inside of the chamber 22 in a sufficiently reduced pressure state. Then, valve 23a is closed, and valve 2
3b is opened and compressed air is blown into the parison from the blow pin. By opening the valve 23b, the groove 13a
, 14a and air suction holes 16a, 16b, the air between the parison and the mold is rapidly sucked. It is desirable to open the valve 23b at the same time as or just before the blowing of compressed air.

[0027]

[Examples] The present invention will be explained in detail with reference to Examples below.

<Example 1> A. Parison. (1) Layer structure Two layer structure. (2) Outer layer (a) Plastic - high density polyethylene. (b) Filler---■Material Synthetic silica (Syroid 244 manufactured by Fuji Davison). ■Diameter 1.8μm. ■Refractive index 1.46 ■Filling amount 40.0% by weight. (3) Inner layer high density polyethylene.

B. Molding method. Molded using the mold and air suction means shown in Figures 3 and 4.

C. container. (1) Shape: Bottle-like with a narrow mouth. (2) Thickness of each layer. (a) Outer layer 70 μm. (b) Inner layer 700 μm.

<Examples 2 to 5> The filling amount of the filler was 20.0% by weight, 10.0% by weight, 5.0% by weight, and 2% by weight, respectively.
．． A container was molded in the same manner as in Example 1 except that the amount was 5% by weight.

<Comparative Example 1> A container was molded in the same manner as in Example 1 except that no filler was filled.

Table 1 shows the 60 degree mirror reflectance (%) and haze (%) of Examples 1 to 5 and Comparative Example 1.

[0034]

[Table 1]

<Example 6> A. Parison. (1) Layer structure Two layer structure. (2) Outer layer (a) Plastic - polypropylene. (b) Filler---■Material: True spherical synthetic silica (Tospar 3120 manufactured by Toshiba Silicone Co., Ltd.). ■Diameter 12.0μm. ■Refractive index 1.44 ■Filling amount 40.0% by weight. (3) Inner layer polypropylene.

B. Molding method. Molded using the mold and air suction means shown in Figures 3 and 4.

C. container. (1) Shape: Bottle-like with a narrow mouth. (2) Thickness of each layer. (a) Outer layer 50 μm. (b) Inner layer 650 μm.

<Examples 7 to 10> The filling amount of the filler was 20.0% by weight, 10.0% by weight, 5.0% by weight, respectively.
A container was molded in the same manner as in Example 6 except that the amount was 2.5% by weight.

<Comparative Example 2> A container was molded in the same manner as in Example 6 except that no filler was filled.

Table 2 shows the 60 degree mirror reflectance (%) and haze (%) of Examples 6 to 10 and Comparative Example 2.

[0041]

[Table 2]

<Example 11> A. Parison. (1) Layer structure Two layer structure. (2) Outer layer (a) Plastic - linear low density polyethylene. (b) Filler────■Material Magnesium carbonate (chemical formula: 4MgCO3・Mg(OH)2・4H2
O). ■Diameter 10.0μm. ■Refractive index 1.52-1.53. ■Filling amount 40.0% by weight. (3) Inner layer linear low density polyethylene.

B. Molding method. Molded using the mold and air suction means shown in Figures 3 and 4.

C. container. (1) Shape: Bottle-like with a narrow mouth. (2) Thickness of each layer. (a) Outer layer 50 μm. (b) Inner layer 500 μm.

<Examples 12 to 15> The filling amount of the filler was 20.0% by weight, 10.0% by weight, and 5.0% by weight, respectively.
A container was molded in the same manner as in Example 11, except that the content was 2.5% by weight.

<Comparative Example 3> A container was molded in the same manner as in Example 11 except that no filler was filled.

Table 3 shows the 60 degree mirror reflectance (%) and haze (%) of Examples 11 to 15 and Comparative Example 3.

[0048]

[Table 3]

[0049]

[Effects] As described above, according to the present invention, it is possible to obtain a plastic multilayer blow container that has excellent transparency, low surface gloss, and a luxurious appearance.

[0050]

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the layer structure of an embodiment of a plastic multilayer blow container according to the present invention.

FIG. 2 is a cross-sectional view showing the layer structure of another example.

FIG. 3 is a perspective view of a mold for molding a container according to the present invention.

FIG. 4 is an explanatory diagram of air suction means for molding.

[Explanation of symbols]

1. Inner layer. 2. Outer layer. 10　　　　　Mold. 10a Parting surface. 12 Recessed part. 13. Vacuum suction recess. 14. Vacuum suction recess. 15a Air suction hole. 15b Air suction hole. 16a Communication hole. 16b Communication hole. 17a Air suction hole. 17b Air suction hole. 18. Stopper. 20 Air suction means. 21 Vacuum pump. 22 Chamber. 23a Tube. 23b pipe. 24a Valve. 24b Valve.

Claims (2)

[Claims] Claim 1: A plastic multilayer blow container consisting of an outer layer and an inner layer, wherein the outer layer has a total thickness of 1.0 to
This outer layer has a particle size of 1.0 to 15.0μ.
filler with a refractive index of 1.44 to 1.60 at 1.0 to 50 m
A plastic multilayer blow container characterized in that it is made of plastic containing % by weight. 2. The plastic multilayer blow container according to claim 1, wherein the inner layer comprises a layer containing regrind plastic, or a multilayer structure of a layer containing regrind plastic and another plastic layer.