JPS59155438A - Method for coating oriented polyethylene terephthalate bottle with polyvinylidene chloride resin - Google Patents

Abstract

PURPOSE:To form a resin coating having a good surface appearance at a relatively small amount of resin coated and being still uniform, by effecting the coating with a polyvinylidene chloride resin coating solution at least twice in carrying out the titled coating. CONSTITUTION:The surface of an oriented polyethylene terephthalate bottle is coated with a primer polyvinylidene chloride resin coating solution by, for example, dipping. While the bottle is being rotated, it is squeezed, without passing a curing step, with felt, cloth, blade, or the like to scrape off extra solution and thereby form a thin polyethylene terephthalate film. A top coating polyvinylidene chloride resin coating solution is applied to the thin film of this undercoated polyvinylidene chloride resin by, for example, spraying, necessary times, and the applied solution is aged under a curing condition to coat the bottle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating polyvinylidene chloride resin onto stretched polyethylene terephthalate bottles.

Stretched polyethylene terephthalate bottles have advantages such as transparency, light weight, and strength, so in recent years they have been widely used as packaging containers for products such as soybean oil, juices, salad dressings, and alcoholic drinks.They are also used for carbonated drinks. I started to feel bad.

However, although the gas barrier property of polyethylene terephthalate is better than that of olefin 41# resin, it is inferior to polyvinylidene chloride, which has the best gas barrier property among synthetic lake resins. For this reason, in the case of a bottle with a small internal gkA, the contents to be packaged are greatly affected by oxygen gas passing through the container wall, and the degree to which the fugitive contents are dissipated into the atmosphere through the container wall increases. is large.

Therefore, improving the gas barrier properties of stretched bottles made of polyethylene terephthalate is necessary for retaining one content and reducing the capacity, and it has been considered to coat the bottle wall with polyvinylidene chloride resin.

However, due to the coating taste such as spray coating method, polyethylene terephthalate! Even if you try to coat the wall of the stretched bottle with polyvinylidene chloride resin,
This is due to the poor elasticity of polyvinylidene chloride resin with polyethylene terephthalate and poor fluidity.
After curing, the surface of the fabric is in poor condition, and unevenness and wrinkles are likely to occur, making it impossible to obtain a product of good quality. In order to improve adhesion with polyethylene terephthalate, it is sufficient to improve the wetting of the coating liquid to the surface to be coated.Methods to improve wetting include surface treatment of the surface to be coated, such as corona discharge treatment, flame treatment, and chemical treatment. Techniques such as chemical cleaning treatment and anchor coating are generally known.

However, these processing methods have the disadvantage that the steps are complicated and it is difficult to implement them in-line.

As a result of research on a method for uniformly coating polyvinylidene chloride/silica on the wall surface of a stretched bottle made of polyethylene terephthalate, the inventor found that by first coating the polyethylene terephthalate surface with a polyvinylidene chloride resin coating liquid and then squeezing it. By removing excess coating liquid, a thin film is formed on the polyethylene terephthalate surface, and then by applying a top coat, a uniform and good surface condition can be achieved with a relatively small amount of resin applied on the polyethylene terephthalate surface. It was discovered that it was possible to form a polyvinylidene chloride resin coating, and based on this knowledge, the present invention was completed.

That is, the gist of the present invention is to provide a method for coating a polyvinylidene chloride resin onto a stretched bottle made of polyethylene terephthalate, in which coating of a polyvinylidene chloride resin agent is carried out in two steps.
Immediately after applying the polyvinylidene chloride resin liquid in the first Reifu process, the excess coating liquid is scraped off by the ironing process, so that it is uniform and smooth on the polyethylene terephthalate surface. A thin polyvinylidene chloride resin undercoat L- is formed, and then (
1 Furthermore, polyvinylidene chloride 11 (polyvinylidene chloride to a polyethylene terephthalate stretched bottle characterized by applying a fat coating liquid and then curing the coating film) for the required number of times .

The method of the present invention will be explained in detail below.

Immediately after coating the polyvinylidene chloride resin coating liquid on the wall surface of the polyethylene terephthalate stretched bottle to be coated, the excess coating liquid is scraped off by an ironing process, and a uniform and thin polyvinylidene chloride resin is coated on the polyethylene terephthalate surface. A resin undercoat layer is formed, and then a polyvinylidene chloride resin coating solution is coated on top of it the required number of times, and then the coating film is cured to form a polyurethane resin with a uniform and good surface condition. Form a film using vinylidene chloride resin.

The polyvinylidene chloride resin for the undercoat may be of the same grade as the polyvinylidene chloride resin image solution for the topcoat, or may be different. The coating method may be any one of i-coating method, roll coating method, and spray coating method.

After coating, the polyethylene terephthalate stretched bottle is squeezed with felt, cloth, sponge, blade, or roll while rotating without undergoing a curing process. During this step, excess polyvinyline chloride resin coating liquid is scraped off, leaving a thin film on the polyethylene terephthalate. Topcoat is applied in this state, but this
A spray coat with a sufficient amount of application is preferable. The thus obtained stretched polyethylene terephthalate bottle coated with vinylidene chloride resin was aged under normal curing conditions for polyvinylidene chloride emulsion, and the bottle had a good surface condition as shown in Table 1 below. be. Moreover, the amount of polyvinylidene chloride resin coating liquid required to form a polyvinylidene chloride resin-coated polyethylene terephthalate stretched bottle is smaller than that required for one-time coating.

Next, in the present invention, it is possible to form a polyvinylidene chloride resin coating film with an even better surface condition by applying a low-grade surface treatment to the polyethylene terephthalate surface to which the undercoat is applied and increasing the wet surface tension as much as possible. Become.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 Body diameter 85φ, height 300M, content ffi 1.257 Polyvinylidene chloride resin whose viscosity was adjusted with a solvent was placed in a polyethylene terephthalate stretch-molded bottle with a clean surface; DARAN 820 (W, R).

After spray coating the bottle (manufactured by Brace Co., Ltd.), the bottle was rotated and squeezed with a cloth blade to remove excess coating liquid, and then polyvinylidene chloride resin DARAN 8 was applied.
A 2D spray coat was applied and then cured. Polyvinylidene chloride resin per bottle (dry)
A good coated surface was obtained with a coating amount of 0.95 P.

Example 2 The bottle wall surface of the same bottle used in Example 1 was subjected to surface treatment by electric discharge, and the surface wetting relaxation force was reduced to 72 dynA.
Same as above until n. After spray-coating polyvinylidene chloride resin (DARAN 820) on the surface-treated bottle wall, the bottle was rubbed with a cloth blade while rotating to remove excess coating liquid, and then polyvinylidene chloride resin (DARAN 82) was applied. D was spray coated and then cured.・The amount of polyvinylidene chloride resin (dry) applied per bottle is 1
．． A good coating surface was obtained with 294/bottle.

Example 3 Polyvinylidene chloride resin with alcohol added to the bottle wall of the same bottle used in Example-1; Surfen 2
After soaking in 011 (manufactured by Morton Chemical Co.) and scrubbing with a sponge roller, a polyvinylidene chloride resin i DARAN 820 was spray coated and then cured. A good coated surface was obtained by coating one bottle of polyvinylidene chloride resin (when dry) at ff 1.12.

Comparative Example The same bottle used in Example 1 was spray coated with polyvinylidene chloride resin (DARAN 820) without undercoating to form a polyvinylidene chloride PA fat coating, but wrinkles and unevenness occurred. A good surface was not obtained.

Table 1; Coating method and coating surface properties

Claims (1)

[Claims] In a method of coating polyvinylidene chloride<lj H& on a stretched bottle made of polyethylene terephthalate,
It is important to apply the polyvinylidene chloride resin coating solution to the kettle twice or more, and in the first coating process, remove excess Perform a dropping operation to form a uniform and thin lower peaked layer of polyvinylidene chloride resin on the polyethylene terephthalate surface, and further apply a polyvinylidene chloride emulsion liquid over it the required number of times,
A method for coating polyvinylidene chloride resin on a stretched bottle made of polyethylene terephthalate, which comprises curing the coating film after a certain period of time.