JP2000006231A - Plastic container with label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a container from deforming due to the difference between the shrinkage factor of a container main body and that of a label after the molding of the container and, at the same time, provide the container having no limitation for the quality of material and kind of a label to be used in an in-mold labelling container, in which blow molding and labelling are simultaneously executed. SOLUTION: In a plastic container with a label, which is formed by blow- molding a plastic material in a mold with a label arranged in advance therein, 0.2-7.0 wt.% of organic crystalline nucleus forming agent is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container manufactured by blow molding, and more particularly, to a method in which a label is placed in a blow mold in advance and a plastic material is blown in the mold. The present invention relates to a molded plastic container with a label.

[0002]

2. Description of the Related Art A technique for placing a label in a blow mold in advance and performing labeling simultaneously with molding of a container is generally known as in-mold labeling. The use of in-mold labeling technology eliminates the need for a labeling step after the container is formed, thereby reducing manufacturing costs, as well as providing strong adhesion between the container and the label and for the label to be completely integrated with the container. It can be made difficult to peel off. On the other hand, a disadvantage of in-mold labeling is that the container is deformed due to a difference in shrinkage between the container body and the label after the container is formed.
After molding, the container body is cooled from the molding temperature to the removal temperature, so that after the container is removed, contraction occurs due to relaxation of residual stress and crystallization. This shrinkage is promoted by the delay of the cooling of that part because the label is interposed between the mold and the container body. However, the amount of shrinkage of the label after molding is considerably smaller than that of the container body, and as a result, the container is deformed.

In order to solve this problem, some means have been proposed and some of them have been put to practical use. The first method is to predict the deformation amount of the container in advance and change the shape of the cavity of the mold in accordance with the contraction amount, so that a predetermined shape is finally obtained after the deformation. However, in this method, it is difficult to predict the amount of deformation, and it is necessary to change the shape of the mold cavity several times. The second method is to prevent deformation of the container by using a label having a large amount of shrinkage so that the container and the label have the same amount of shrinkage. This method does not require a troublesome step of changing the shape of the mold cavity. However, a disadvantage of this method is that there are restrictions on the labels used. That is, a label with a small amount of shrinkage cannot be used. Thirdly, a method has been proposed in which the container is rapidly cooled with liquid nitrogen or the like from the inside of the container during blow molding to reduce the amount of shrinkage of the container body, but the molding apparatus becomes expensive and is not practical.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the above-mentioned problems, that is, in an in-mold label container which is labeled at the same time as blow molding, a container after the container is formed. It is an object of the present invention to provide a container that prevents a container from being deformed due to a difference in shrinkage ratio between a main body and a label and that is not limited in the material and type of a label to be used.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. According to the first aspect of the present invention, a label is placed in a blow mold in advance, and a plastic material is blow-molded in the mold. Plastic container with 0.2% by weight of organic crystal nucleating agent in the plastic
A plastic container with a label characterized by being added in an amount of not more than 7.0% by weight.

According to a second aspect of the present invention, there is provided the labeled plastic container according to the first aspect, wherein the plastic container is a single-layer or a multi-layer container made of a polypropylene resin.

According to a third aspect of the present invention, there is provided the labeled plastic container according to the first or second aspect, wherein the organic crystal nucleating agent is a sorbitol derivative.

1 and 2 show an example of a plastic container according to the present invention. In FIG. 1 and FIG. 2, a plastic container 1 comprises a container body 2 formed by blow molding and a label 3 attached to the outer surface thereof simultaneously with the molding. It consists of.
Important features of the plastic container according to the invention are:
An organic crystal nucleating agent is added to the plastic material forming the container body 2 in an amount of 0.2% by weight or more and 7.0% by weight or less. The shrinkage of the container body 2 is reduced by adding a nucleating agent. Therefore, as a result, label 3
The difference in shrinkage between the container body 2 and the container body 2 is eliminated, and deformation can be prevented.

The plastic material constituting the container body 2 is not particularly limited as long as it is a material that can be blow-molded with crystallinity. Polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyamide resin, ethylene resin
A bilyl acetate copolymer resin or the like can be used, and the configuration of the container body 2 can be a single layer or a multilayer of the above resin. However, it is particularly preferable to use a single-layer or multi-layer container made of a polypropylene resin in which the nucleating effect of the nucleating agent is easily exhibited. Further, among them, a polypropylene block copolymer resin has a high degree of crystallinity and is excellent in impact resistance, and thus is preferable as a material constituting the container body. In addition, the container may be manufactured by any method such as direct blow molding, injection blow molding, and stretch blow molding.

The nucleating agent used is preferably an organic one.
Inorganic crystal nucleating agents such as talc have a small nucleating effect,
When added at a high concentration, physical properties such as impact resistance of the container are reduced. Further, it is necessary to add the organic crystal nucleating agent in an amount of 0.2% by weight or more in order to exhibit a nucleating effect, and preferably, by adding 0.3% by weight or more, a higher nucleating effect. Can be expressed. The upper limit is 7.0% by weight, preferably 5.0%, from the effects of the amount of the organic crystal nucleating agent added, the deterioration of moldability, the price of the crystal nucleating agent, and the like.
% By weight. Further, as the kind of the organic crystal nucleating agent to be used, dibenzylidene sorbitol, sorbitol derivatives such as dimethylbenzylidene sorbitol, phosphorus crystal nucleating agent, carboxylic acid mixture and the like can be used.
Among them, sorbitol derivatives are most preferred in terms of the nucleation effect.

There is no particular limitation on the material and structure of the label 3, and any of paper, plastic, and synthetic paper can be used. <Operation> According to the present invention, an in-mold label container that does not deform after molding can be provided, and there is no limitation on the material of the label attached to the container.

[0011]

EXAMPLES Examples of the present invention and comparative examples are shown below.

(Example 1) A synthetic paper having a thickness of 0.2 mm was placed in a blow molding die, and a melt flow rate was set to 0.2.
A container having an inner volume of 700 ml shown in FIG. 1 was molded by direct blow molding using a g / 10 min polypropylene random copolymer resin. A 0.2% by weight of a dimethylbenzylidene sorbitol crystal nucleating agent was previously added to the polypropylene random copolymer resin. The molded container had a good appearance without deformation after molding.

(Example 2) A paper having a thickness of 0.2 mm was placed in a blow mold, and the melt flow rate was 3.0 g /
Using a polypropylene random copolymer resin of 10 min as the outer layer resin and a polypropylene block copolymer resin having a melt flow rate of 0.1 g / 10 min as the inner layer resin, a multilayer container having an inner volume of 700 ml shown in FIG. 1 was formed by direct blow molding. . Each layer ratio was an inner layer 90 to an outer layer 10. Also, a dimethylbenzylidene sorbitol crystal nucleating agent was previously added to the polypropylene block copolymer resin in an amount of 0.23% by weight. This means that 0.2% by weight of the nucleating agent was added to the whole container. The molded container had a good appearance without deformation after molding.

Comparative Example 1 A container was formed in the same manner as in Example 1. However, no nucleating agent was added to the used polypropylene random copolymer resin. In the obtained container, the label bonding portion was significantly deformed outward due to the contraction of the container body after molding.

Comparative Example 2 A container was molded in the same manner as in Example 2. However, only 0.15% by weight of a nucleating agent was added to the used polypropylene block copolymer resin. In the obtained container, the effect of the crystal nucleating agent was not sufficiently exhibited, and the label bonding portion was deformed outward due to shrinkage of the container body after molding.

Comparative Example 3 A container was formed in the same manner as in Example 1. However, 8.0% by weight of a crystal nucleating agent was added to the used polypropylene block copolymer resin. In the obtained container, the effect of the crystal nucleating agent was sufficiently exhibited, but the moldability was poor and the cost was high.

[0017]

According to the present invention, an in-mold labeling container free from deformation after molding can be easily manufactured,
The material of the label to be used can also be freely selected.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of a plastic container of the present invention.

FIG. 2 is an enlarged sectional view of one embodiment of the plastic container of the present invention.

[Explanation of symbols]

 1. Plastic container 2. Container body 3. Label

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B29K 23:00 B29L 9:00 22:00 F term (reference) 3E062 AA09 AC02 DA02 DA07 4F208 AA11 AB08 AD09 AG07 AH55 AR20 LA05 LB01 LB19 LB22 LG01 LG22 LG28 4J002 BB031 BB061 BB121 BP021 CF061 CL001 EF006 EL106 EW006 FD206 GG01

Claims (3)

[Claims] 1. A plastic container with a label in which a label is placed in a blow mold in advance and a plastic material is blow-molded in the mold, wherein the plastic contains an organic crystal nucleating agent in an amount of 0.2% by weight or more. A plastic container with a label, which is added in an amount of 7.0% by weight or less. 2. The container according to claim 1, wherein said plastic container is a single-layer or multi-layer container made of polypropylene resin.
Labeled plastic container. 3. The labeled plastic container according to claim 1, wherein the organic crystal nucleating agent is a sorbitol derivative.