JPS6323310Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> The present invention relates to a paper liquid-tight container. More specifically, the present invention relates to a paper liquid-tight container that exhibits less foaming when filled with liquid contents. <Conventional technology> Traditionally, milk, juice, soup, soybean oil,
Paper containers used to seal beverages and liquid foods such as alcoholic beverages, salad oil, and tempura oil include Gebert-top type containers, flat-top square paper containers, and even paper containers with metal lids for the top and bottom lids and paper and plastic containers for the canisters. A cylindrical composite can using a laminated pair of films is known as a composite sealed container for liquids using paper. All of these are characterized by having a synthetic resin film layer such as polyolefin resin on the innermost layer that comes into contact with the liquid, but by combining paper as the main material with aluminum foil, etc., we can take advantage of the strengths of each and save on containers. Among the products that have been rapidly growing in recent years, they meet social needs such as resource conservation, energy conservation, bottle and can pollution control, and aim not only to improve the original quality and functionality of containers, but also to improve logistics efficiency and product image. It is one of the. <Problems to be solved by the invention> Liquid products using these containers are usually filled at high speed using automatic filling machines, but products such as milk, milk drinks, juices, and soups tend to foam easily during filling. Due to this, the filling speed during filling may be restricted, leading to a decrease in production efficiency.Furthermore, when sealing the container, bubbles may adhere to the container seal, impairing the sealing performance. It could happen. In addition, when such a device is used to fill the liquid while measuring it, and the measuring method is performed in units of volume, the content tends to vary widely due to foaming. For this reason, the container had to take up somewhat more head space, and improvements were desired in terms of materials as well. <Means for solving the problems> The present invention was devised to improve these current problems, that is, it consists of a laminate of at least two or more layers mainly made of paper, and the innermost layer has a synthetic material. In a liquid sealed container having a resin layer,
By using an antifogging agent in the innermost synthetic resin layer, the contact angle between the synthetic resin layer and water under atmospheric pressure was reduced to 60° or less, which is an extremely novel solution. It is an idea. Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows the changes in the shape of a Goebel top-type paper container after it is made into a box, filled with a liquid content, and then the container is top-sealed. That is, when the container A is in the assembled state as shown in A, the liquid content is filled,
After that, the roof part B goes through the state shown in B, and finally, as shown in C, parts a and b of A are heat-sealed and hermetically filled. In this case, if the liquid content is filled at a high speed and excessive foaming occurs, not only will the filling speed be restricted, but some of the foam may adhere to the heat seal parts a and b, impairing the sealing performance. becomes. The present invention was devised to solve such problems, but the following are the factors that can cause foaming. In other words, (1) Wetting index of the material on the inner surface of the container that comes into contact with the liquid (according to the measurement method based on JIS K-6768) (2) Contact angle with the material on the inner surface of the container that comes into contact with the liquid (3) Smoothness of the inner surface of the container (4) The main factor is considered to be the shape of the container. As a result of intensive research on these issues, it has become clear that, in addition to the shape and smoothness of synthetic resin film laminated paper containers, the size of the contact angle between the liquid and the inner surface of the container is a major factor. Ta.
That is, when the contact angle (θ) between the liquid 1 and the inner surface 2 of the container is large, as shown in Figure 2A, the foaming will be intense during filling, and when the contact angle (θ) is small as shown in Figure 2B, the foaming will be severe. It turned out that there was little. Based on this experimental result, the inventor of the present invention used an antifogging agent, which is a type of surfactant, in the synthetic resin of the inner layer of the container to reduce the contact angle and improve the foaming property when filling the container. I discovered that I could keep it to the bare minimum. FIG. 3 shows a part of a cutaway front view of the paper liquid-tight container according to the present invention, and the container consists of a basic paper base 3 and a synthetic resin layer 4, which is the innermost layer, laminated thereon. In the present invention shown in FIG. 3, the antifogging agent 5 is uniformly blended into the innermost synthetic resin layer 4. According to this, compared to the currently used paper liquid-tight container shown in Figure 3 A, the present invention shown in Figure 2 2 produces less foaming when filling liquid contents, and can stably perform high-speed filling. At the same time, it is possible to prevent the sealing performance of the seal portion from being impaired. As the synthetic resin that can be used in the present invention, any resin that can be coated or laminated can be used, and the synthetic resin is not limited to the present invention. Specifically, polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, acrylic acid, or methacrylic acid and olefin copolymer resin, or α having 3 to 12 carbon atoms
Examples include polyolefin resins such as -olefin polymers or ethylene-α olefin copolymer resins, polystyrene, polycarbonate, polyvinyl chloride, polyester, and polyamide resins. Practically speaking, polyolefin resins such as polyethylene are considered to be optimal in terms of processing suitability, functionality, cohesion, etc. Further, the antifogging agent added to the synthetic resin of the present invention improves wetting of the container surface by imparting hydrophilicity to the plastic film surface. That is, by arranging the active agent densely on the film surface with the hydrophilic groups facing outward, water molecules are attracted to the container surface and foaming is suppressed. As specific examples, the following can be used, taking into account that they are used in beverage containers. That is, glycerin fatty acid ( _C8 - _C22 ) ester, sorbitan fatty acid ( _C8 - _C22 ) ester,
Propylene glycol fatty acid ( _C8 - _C22 ) ester, sucrose fatty acid ( _C8 - _C22 ) ester, citric acid mono(di or tri)stearyl ester, pentaerythritol fatty acid ( _C8 - _C18 ) ester,
Trimethylolpropane fatty acid ( _C8 - _C18 ) ester, polyoxyethylene (20 mol) glycerin fatty acid ( _C12 - _C18 ) ester, polyoxyethylene (20 mol) sorbitan fatty acid ( _C12 - _C18 ) ester, polyethylene Glycolic fatty acids ( _C8 - _C22 )
ester, polypropylene glycol fatty acid (C ₈ - C ₁₈ ) ester, polyoxyethylene fatty alcohol (C ₁₂ - C ₂₀ ) ether, polyoxyethylene (4 - 50 mol) alkyl (C ₄ or more) phenyl ether, fatty acid (C Specific examples include condensation products of _C12 to _C18 ) and diethanolamine, polyoxypropylene, polyoxyethylene block polymers, and polypropylene glycol, and the effects can be further enhanced by using these alone or in combination. In addition, in the present invention, the combined use of an anti-fog agent refers to the addition and mixing of an anti-fog agent to a synthetic resin, as well as the use of a very thin coating or spray coating of an anti-fog agent on the surface of a synthetic resin. It refers to the method. As a specific example of the laminate of two or more layers of paper and synthetic resin described in the present invention, it goes without saying that in addition to the paper/polyolefin resin structure, metal foil such as aluminum foil may be laminated in the layers. stomach. Forms of the paper liquid sealed container described in the present invention include Gebel top type or flat top type square paper containers and triangular paper containers, as well as cylindrical spiral type and flat roll type composite cans. <Effect of the invention> In experiments by the inventor, one of these antifogging agents or a mixture of these antifogging agents was appropriately mixed with a synthetic resin, and the contact angle between the formed synthetic resin layer and water was determined. By adjusting the amount of antifogging agent added so that the temperature is 60° or less when exposed to the atmosphere, a paper liquid-tight container with minimal foaming properties can be created without excessive foaming when filling liquid contents. It turns out that it can be obtained. The reason for the effect obtained by adding such an antifogging agent is that the properties of the antifogging agent itself improve the leakage of liquid contents from the surface of the synthetic resin, reduce the contact angle (ο), and reduce the contact angle (ο) during filling. This is thought to have the effect of limiting the foaming properties of. <Example> A synthetic resin film containing various antifogging agents was laminated onto a base paper having a basis weight of 360 g/m ² by an extrusion molding method or a lamination method, and the thickness of the resin layer was standardized to 20 μm. Next, a Gaebert top-type paper container with a volume of 1 was made using the composite laminate with this base paper with the synthetic resin layer inside, and milk with a liquid temperature of 5°C was poured into the container at a filling speed of 550 ml/sec. We compared and confirmed the gender. Table 1 shows the results as a list. Compared to the conventional product configuration (synthetic resin alone), the Gebert-tipped paper container mixed with the antifogging agent described in the present invention produced less foam when filled with milk. The results were extremely good with minimal corrosion.

【table】

【table】

(Note) Foaming judgment ○: Little foaming, good filling properties

[Brief explanation of the drawing]

Figures 1A, 1B, and 1C are perspective views showing changes in the form of a Goebelt-top type paper liquid-tight container after it is made into a box, filled with liquid contents, and then sealed with the top. Figures 2A and 2B are explanatory diagrams showing the relationship between the contact angle between the liquid and the inner surface of the container, Figure 3A is a partially omitted front sectional view of a conventional paper liquid-tight container, and Figure 3B is BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially omitted front sectional view showing an embodiment of a paper liquid-tight container of the present invention. A... Container, B... Goebel portion, 1... Liquid, 2... Inner surface of container, 3... Paper base, 4... Innermost synthetic resin layer, 5... Antifogging agent.

Claims (1)

[Claims for Utility Model Registration] (1) In a sealed container for liquids that is composed of a laminate of at least two or more layers mainly made of paper and has a synthetic resin layer as the innermost layer, A paper liquid-tight container characterized in that the contact angle between the synthetic resin and water is 60° or less under atmospheric pressure by using an anti-fogging material. (2) The paper liquid-tight container according to claim 1, wherein the innermost synthetic resin layer is made of polyolefin resin.