JPS6235396B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plastic container with excellent storage stability, and more particularly, to a plastic container that has a combination of ultraviolet ray barrier properties and gas barrier properties, and is capable of preserving foods for a long period of time. . Plastic bottles made by melt extruding thermoplastics such as polyolefin and blow molding are lighter than glass bottles and have excellent impact resistance, so they are used in various fields as an alternative to glass bottles. It has come to be used in Although general-purpose plastics such as polyolefins have excellent moisture resistance and hygienic properties, they have a relatively high oxygen permeability coefficient, and oxygen permeation through the bottle wall occurs at a non-negligible level, so they cannot be used for long-term storage of food products. It is unsuitable for containers for storage purposes and containers for cosmetics that require fragrance retention. In order to improve this drawback, plastic bottles whose walls are made of resin with excellent oxygen barrier properties have already been developed. Currently, the resin with the best oxygen barrier properties among melt-extrudable thermoplastic resins is saponified ethylene-vinyl acetate copolymer (ethylene-vinyl alcohol copolymer), but this saponified copolymer , they have poor moisture resistance, that is, water vapor barrier properties, and their oxygen permeability coefficients tend to increase significantly as humidity increases.Thus, when used in actual plastic bottles, it is necessary to layer them with moisture-resistant resins such as polyolefins in a sandwich-like manner. It is used as a bottle in the form of a multilayer laminate. Another problem with plastic bottles is that the above-mentioned polyolefins and ethylene-vinyl alcohol copolymers have extremely high transmittance to ultraviolet rays. This means that ultraviolet rays can pass through a large amount even in a container made of the body. For this reason, although the above-mentioned packaged foods using plastic containers may be somewhat satisfactory for the purpose of preventing the contents from going rancid, the ultraviolet rays that pass through the container wall may damage pigments, oils, and fats.
There is a problem in that animal proteins, various beverage extracts, etc. deteriorate, impairing the flavor, appearance, and hygienic characteristics of the food contents. Conventionally, as a means of blocking ultraviolet rays in plastic containers, it has been known to incorporate an ultraviolet absorber into the resin constituting the plastic container, but such a method has problems with the hygienic properties of the container, and Its ultraviolet blocking effect is still not fully satisfactory. Additionally, plastic containers are inferior to glass containers in terms of transparency and see-through properties; in particular, the polyolefin resin layer in plastic containers appears cloudy when transparent contents are viewed through, and dark and cloudy when colored contents are viewed through. There is a problem of giving a feeling (for example, Japanese Patent Application Laid-Open No. 1983-
(See Publication No. 116387). Furthermore, the polyolefin resin used as the inner layer of plastic containers has the ability to adsorb various low-molecular substances, such as the pigments in the contents.
Adsorbs fragrances, vitamins, beverage extracts, etc. to reduce the flavor of the contents, or conversely, releases odor components or monomer components adsorbed during container manufacturing into the contents to improve the flavor of the contents. The problem is that it damages the Therefore, an object of the present invention is to provide a plastic container which has a combination of barrier properties against ultraviolet rays and gas barrier properties and is capable of preserving food products for a long period of time without deterioration. Another object of the present invention is to provide a plastic container which, in addition to the above-mentioned properties, has improved see-through properties for its contents. Still another object of the present invention is to provide a plastic container which, in addition to the above-mentioned characteristics, prevents the adsorption of the polyolefin inner surface. According to the present invention, a plastic container includes a melt-moldable moisture-resistant thermoplastic resin layer and a layer mainly composed of an ethylene-vinyl alcohol copolymer, and at least one surface thereof is the moisture-resistant thermoplastic resin layer. In the substrate, in a position adjacent to the moisture-resistant thermoplastic resin layer, (a) 99 to 70% by weight of vinylidene chloride, and (b) 1 to 30% by weight of the following formula, In the formula, R ₁ represents a hydrogen atom or a methyl group, and X represents a nitrile group or a formula, (In the formula, Y is an alkyloxy group, a hydroxyalkyloxy group, or a glycidyloxy group)
a group represented by, at least one monomer represented by: and (c) containing up to 50 parts by weight of chlorine, excluding vinylidene chloride, per 100 parts by weight of the total amount of the monomers (a) and (b). A copolymer consisting of at least one type of ethylenically unsaturated monomer, which has an oxygen permeability coefficient of 9×10 ^-14 cc・cm/cm ²・sec・cmHg or less and a water vapor permeability coefficient at 20°C and 100%RH. (JIS Z-0208) is 3×10 ^-3 g・
A plastic container with excellent storage stability is provided, which is characterized by being provided with a coating layer having a thickness of cm/m ² ·day or less. In FIG. 1 showing an example of a bottle-shaped coated plastic container, the bottle 1 has a circumferential wall portion 2 having a circular or elliptical cross section, a bottle mouth portion 3 integrally connected to the circumferential wall portion 2, and a bottle opening portion 3 continuous to the lower end of the circumferential wall portion. It consists of a bottom part 4. As shown in the enlarged cross-sectional views in Figures 2-A to 2-C, the walls of these bottles are mainly made of melt-moldable moisture-resistant thermoplastic resin layers 5 and 6 and ethylene-vinyl alcohol copolymer. a coating layer 9 of vinylidene chloride-acrylic (methacrylic) copolymer (hereinafter sometimes referred to as polyvinylidene chloride resin) applied to at least one surface of the substrate 8; 9'. In the preferred embodiment shown in FIG. 2, the container substrate 8 has two moisture-resistant thermoplastic resin layers 5 and 6 sandwiched therebetween by a layer 7 based on ethylene-vinyl alcohol copolymer. Both surfaces of this container substrate 7 are provided with coating layers 9 and 9' of vinylidene chloride-acrylic (methacrylic) copolymer. An important feature of the present invention is that the vinylidene chloride-acrylic (methacrylic) copolymer detailed below is
In addition to exhibiting excellent adhesion to the laminated structure of plastic container substrates, the UV blocking properties of the entire container wall can be significantly improved by simply providing a coating layer of the copolymer layer on the plastic container substrate. Based on new knowledge. The fact that the container wall of the present invention has excellent UV blocking properties is immediately apparent by reference to FIG. That is, curve A in FIG. 3 corresponds to the plastic container substrate 8 in Example 3, which will be described later, that is, the container wall made only of polyolefin (low-density polyethylene)/ethylene-vinyl alcohol copolymer mixture/polyolefin (low-density polyethylene). , which shows the relationship between wavelength and transmittance. According to this curve A, it can be seen that the above-mentioned plastic container exhibits a considerably high transmittance for ultraviolet light having a wavelength of 210 to 400 mμ, similar to visible light. On the other hand, curve B is a wavelength-transmittance curve of the plastic container substrate 8 coated with a 30μ thick coating of vinylidene chloride-acrylic (methacrylic) copolymer. It can be seen that UV blocking properties can be obtained by simply applying a coating of only 30 microns to the container substrate. The coated plastic containers of the present invention also have the unexpected advantage of providing permanent UV protection. That is, curves C and D in FIG.
60℃, 25 hours and 60℃ with Weatherometer, respectively.
This is a wavelength-transmittance curve of a sample exposed to ultraviolet light for 50 hours. According to these curves C and D, in the coated plastic container of the present invention, the more it is irradiated with ultraviolet rays, the more the transmittance of ultraviolet rays is suppressed to a lower level, and the absorption wavelength is further shifted to the longer wavelength side. It is clear that there is a transition. Thus, the more a coated plastic container according to the invention is irradiated with UV light, the more it acts to prevent the transmission of UV light, and even when subjected to prolonged UV exposure, the overall UV light is reduced. This makes it possible to suppress the amount of transmission to a significantly low level. The reason for this is thought to be that conjugated diene bonds are formed in the vinylidene chloride-acrylic (methacrylic) copolymer layer as the layer is irradiated with ultraviolet rays, and these conjugated diene bonds act to absorb more ultraviolet rays. In the present invention, it is also a significant advantage that this ultraviolet blocking effect is achieved while actually improving the oxygen barrier properties, moisture resistance, and humidity dependence of the oxygen barrier properties of the container wall as a whole. When an ultraviolet absorber or the like is contained in the resin in an amount that provides the same ultraviolet blocking effect as in the present invention, the presence of the ultraviolet absorber naturally reduces the gas barrier properties of the resin layer. On the other hand, the vinylidene chloride-acrylic (methacrylic) copolymer used in the present invention has a remarkable combination of oxygen barrier properties and moisture resistance, and is said to have extremely low humidity dependence of oxygen barrier properties. It has characteristics. That is, this copolymer has an oxygen permeability coefficient of 9×10 ^-14 cc・cm/cm ²・sec・cmHg or less at 20°C and 100%RH,
Water vapor permeability coefficient (JIS Z-0208) is 3×10 ^-3 g・
cm/m ²・day or less. Furthermore, this vinylidene chloride-acrylic (methacrylic) copolymer is provided so as to cover the base multilayer plastic container substrate so as to overlap in the gas permeation direction. Thus, according to the present invention, the above-mentioned gas barrier properties can be further improved due to this lamination effect. In addition to the features described above, the coated plastic containers of the present invention provide several additional advantages. That is, the vinylidene chloride-acrylic (methacrylic) copolymer coating solution has excellent wettability and adhesion to the surface of the plastic container substrate, and is characterized by forming a dense and smooth film on the substrate. are doing. Thus, providing a coating of said copolymer on the outer surface of the substrate eliminates the tendency for the contents to appear cloudy or darkened when viewed through the container wall, thereby improving the viewing properties of the container or even It becomes possible to significantly improve transparency. In addition, vinylidene chloride-acrylic (methacrylic) copolymer has significantly lower adsorption ability for the above-mentioned components than polyolefin resin, etc., so if this copolymer is provided on the inner surface of the container substrate, the adsorption by polyolefin etc. By preventing the release of adsorbed components from polyolefins and polyolefins, it is possible to significantly improve the flavor retention of the contents. The vinylidene chloride-acrylic (methacrylic) copolymer used as the coating layer in the present invention contains (a) 99 to 70% by weight, especially 96 to 80% by weight of vinylidene chloride, (b) 1 to 30% by weight, especially 4 to 80% by weight. 20% by weight of the following formula, In the formula, R ₁ represents a hydrogen atom or a methyl group, and X represents a nitrile group or a formula, (wherein, Y is an alkyloxy group, a hydroxyalkyloxy group, or a glycidyloxy group); at least one acrylic or methacrylic monomer represented by the following; and (c) an optional component. as the total amount of monomers (a) and (b) above.
A copolymer comprising up to 50 parts by weight per 100 parts of at least one chlorine-containing ethylenically unsaturated monomer other than vinylidene chloride, the copolymer having an oxygen permeability coefficient of 9 x 10 ^- at 20°C and 100% RH. ¹⁴ cc・cm／ ^cm2・sec・
cmHg or less and water vapor permeability coefficient (JIS Z-0208)
is 3×10 ^-3 g・cm/m ²・day or less. Specifically, the acrylic or methacrylic monomer (b) includes acrylic acid, acrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, and acrylic. Cyclohexyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, monoglyceride acrylate, methacrylic acid, methacrylonitrile, methyl methacrylate, amyl methacrylate, glycidyl methacrylate, monoglyceride methacrylate,
Examples include 2-hydroxypropyl methacrylate and β-methoxyethyl methacrylate. These acrylic or methacrylic monomers can be used alone or in combination of two or more. Acrylic or methacrylic monomers (b) particularly suitable for the purpose of the present invention include (i) nitrile monomers such as acrylonitrilic acid and methacrylonitrile, (ii) methyl acrylate, ethyl acrylate, and methacrylic acid. Ester monomers such as methyl, 2-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylic acid monoglyceride, methacrylic acid monoglyceride, methoxyethyl acrylate, methoxyethylmethyl methacrylate, and
(iii) A combination of (i) and (ii) above. Examples of the chlorine-containing ethylenically unsaturated monomer (c) as an optional component other than vinylidene chloride include vinyl chloride, ethylene trichloride, ethylene tetrachloride, etc. These monomers may be used singly or in combination. The above combinations can be used. Examples of suitable copolymers include, but are not limited to: Vinylidene chloride/acrylonitrile copolymer, vinylidene chloride/acrylonitrile/methacrylonitrile copolymer, vinylidene chloride/methacrylonitrile copolymer, vinylidene chloride/acrylonitrile/glycidyl acrylate copolymer, vinylidene chloride/acrylonitrile/glycidyl methacrylate Copolymer, vinylidene chloride/acrylonitrile/monoglyceride acrylate copolymer, vinylidene chloride/ethyl acrylate/glycidyl acrylate copolymer, vinylidene chloride/acrylonitrile/ethylene trichloride copolymer, vinylidene chloride/acrylonitrile/vinyl chloride copolymer Polymer, vinylidene chloride/acrylonitrile/monoglyceride methacrylate/ethylene trichloride copolymer, vinylidene chloride/methoxyethyl methyl methacrylate/methyl methacrylate/ethylene trichloride copolymer. In the copolymer used in the present invention, it is important to have 70% by weight or more of vinylidene chloride units in terms of UV blocking properties and gas barrier properties; In order to be able to coat plastic containers without causing damage, it is important to contain at least 1% by weight of acrylic monomer or methacrylic monomer. Additionally, to improve adhesion to various plastic bottle substrates, formula In the formula, each of R ₂ and R ₃ is a hydroxyl group, and these two hydroxyl groups may be dehydrated to form an oxirane ring in an amount of 0.5 to 15% by weight based on the total monomers. It is desirable to use it in Furthermore, in order to further improve the coating performance on plastic bottles, up to 100 parts by weight of other ethylenically unsaturated monomers may be added per 100 parts by weight of the total amount of vinylidene chloride and acrylic or methacrylic monomers. is allowed to contain. The copolymer used in the present invention is generally prepared by emulsifying or suspending the constituent monomers in an aqueous medium by the action of an emulsifier and a dispersant, and then carrying out emulsion polymerization or suspension polymerization in the presence of a radical initiator. can be easily obtained by As the radical initiator, peroxides, azo compounds or redox catalysts which are known per se are used. The copolymer used in the present invention generally has a molecular weight sufficient to form a film. The polymer used in the present invention is generally difficult to mold by hot melting, and is used in the form of an organic solvent solution or in the form of an aqueous emulsion or latex to coat plastic containers by the method described below. The plastic container substrate 8 used in the present invention consists of a melt-formable moisture-resistant thermoplastic resin layer and an ethylene-
The multilayer structure with layers mainly made of vinyl alcohol copolymer also improves the gas barrier properties of the container.
This is extremely important in terms of storage stability. Moisture-resistant thermoplastic resins include thermoplastic resins with a water vapor permeability coefficient of 5×10 ^-1 g・cm/m ²・day (JIS Z-0208) or less, especially low-, medium-, or high-density polyethylene, polypropylene. Olefin polymers such as , ethylene-propylene copolymer, ethylene-butene copolymer, ionomer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / Polyester such as isophthalate; nylon 6, nylon 6.6, nylon 6.
Polyamides such as 10; styrenic copolymers such as polystyrene, styrene-butadiene block copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer (ABS resin); polyvinyl chloride, vinyl chloride-acetic acid Vinyl chloride copolymers such as vinyl copolymers; acrylic copolymers such as polymethyl methacrylate and methyl methacrylate/ethyl acrylate copolymers; polycarbonates, and the like. These thermoplastic resins may be used alone or in the form of a blend of two or more. The effects of the present invention are remarkable when an olefin polymer such as polyethylene or polypropylene is used as the moisture-resistant thermoplastic resin. As the ethylene-vinyl alcohol copolymer, a saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 80 mol%, especially 25 to 60 mol%, and a saponification degree of 90% or more, especially 95% or more, is used. Preferably used. Instead of using this ethylene-vinyl alcohol copolymer alone, other resins such as olefin resins and polyamides may be used within a range that does not impair gas barrier properties, that is, within a range that does not exceed 50% by weight of the total. etc. can be used by blending them. If there is no adhesiveness between the moisture-resistant resin layer and the ethylene-vinyl alcohol copolymer layer, a known adhesive layer may be interposed between the two layers. Examples of such an adhesive layer include olefinic resins graft-modified with ethylenically unsaturated carboxylic acids such as acrylic acid, maleic acid, and maleic anhydride or their anhydrides. Alternatively, instead of interposing an adhesive between the two, at least one of the moisture-resistant resin layer or the ethylene-vinyl alcohol copolymer layer may contain a thermoplastic material, as disclosed in Japanese Patent Publication No. 11263/1983. A carbonyl group polymer may be included to improve the adhesion between the two. This plastic bottle substrate can be produced by a molding method known per se, such as blow molding, biaxial stretch blow molding, injection molding, etc., within the range of having the above-mentioned multilayer structure. Molding into a bottle is easy by blow molding, in which a combination of the aforementioned thermoplastic resins is melt-extruded into a parison shape, the extruded parison is supported in a split mold, and a fluid is blown into the inside of the mold. can be obtained.
In addition, in order to improve the impact resistance and transparency of the bottle, a parison or preform is produced in advance by melt extrusion or injection molding, and this parison or preform is stretched at a temperature below its melting point. It is also possible to form a biaxially molecularly blended plastic bottle by mechanically stretching it in the axial direction and stretching it in the circumferential direction by blowing fluid at the temperature. Furthermore, bottles can also be made by multilayer injection molding. The plastic container substrate used in the present invention can be in the form of a cup or jar. This cup or wide-mouth bottle is made of a multilayer film or sheet formed in advance by coextrusion molding, dry lamination, Sand-German lamination, etc., and then vacuum forming, pressure forming, plug assist molding, etc. It can be obtained by drawing or stretch forming, which are known per se. At this time, the multilayer film or sheet
If the constituent resin layer is subjected to pressure molding, plug assist molding, etc. at a temperature that allows stretching of the constituent resin layer, one or two shafts will be formed on the container wall.
Axial molecular orientation can also be provided. Furthermore, the plastic container substrate used in the present invention can also be an extrudable tube container. This tube container is, for example, published in JP-A-55-5311.
As described in the publication, a thin-walled multilayer plastic bottle with a threaded opening was manufactured by blow molding, the bottom of the bottle was cut off, and the tip of the body wall was heat-sealed. Manufactured. The wall thickness of plastic container substrates can vary widely from relatively thin walls such as extruded tubes to relatively thick walls such as rigid containers. Generally, the wall thickness of the container substrate is between 0.05 and 2.5
mm, preferably in the range of 0.1 to 1.5 mm, and the ratio of the moisture-resistant resin layer and the ethylene-vinyl alcohol copolymer layer is 1:10 to 200:1, especially 1:2.
It is desirable to have a thickness ratio between 150:1 and 150:1.
The present invention is particularly useful for blocking ultraviolet light in plastic containers that require transparency. The coated plastic container according to the present invention is formed by applying an aqueous latex or organic solvent solution of the aforementioned copolymer to at least one surface of the plastic container substrate thus produced, and then drying the formed coating film. be done. In this case, it is preferred to apply the vinylidene chloride copolymer in the form of an aqueous latex, and in this connection it is particularly advantageous to apply it to the surface of the moisture-resistant resin layer of the container substrate. Figures 2-A to 2-C show some examples of suitable combinations of the layer structure of the plastic container substrate and the vinylidene chloride copolymer coating layer. Of course, this coating layer can be on the inner or outer surface of the container substrate. As the aqueous latex of the copolymer, one having a solid content concentration of 20 to 65% and a viscosity of 3 to 500 centipoise is preferably used, while as an organic solvent solution, tetrahydrofuran, ethyl acetate, methyl ethyl ketone, cyclohexane are used. , dimethyl formamide, dimethyl sulfoxide,
Solid content concentration in organic solvent such as dioxane is 5 to 60
% solution is used. The above-mentioned latexes or solutions can be applied to plastic container substrates by dip coating, flow coating, spray coating, brush coating, roller coating, electrostatic coating, slush coating, centrifugal coating, or flow coating. Coating methods known per se can be used, such as spread coating methods, electrophoretic coating methods, and combinations thereof.
The application may be carried out in a single application or in a multi-stage application method of two or more stages.Furthermore, in order to improve the wetting properties of the plastic container substrate, the plastic container substrate may be pre-treated with a frame treatment or an anchoring agent, if necessary. , corona discharge treatment, surfactant coating treatment, chemical etching treatment, etc. may be performed, and conductive treatment for imparting conductivity may also be performed. It is desirable to form the above-mentioned copolymer layer on both surfaces of the plastic bottle, but for the purpose of simultaneously improving the see-through properties, a coating layer is provided only on the outer surface, while preventing gases and aromas from the contents or the plastic layer from being formed. A coating layer may be provided only on the inner surface for the purpose of blocking the release of odor components from the inner surface. Drying of the applied copolymer layer varies depending on the thickness of the coating film, but generally drying at a temperature of 40 to 150°C for about 2 seconds to 60 minutes is sufficient. In addition, in the present invention, the gas and fragrance blocking effect is sufficiently exhibited by the above-mentioned drying alone; however,
If necessary, aging (heat treatment) at a temperature of 30° C. to 120° C. for 10 seconds to 7 days after drying will further enhance the effect. In the present invention, satisfactory results can be obtained if the vinylidene chloride copolymer is provided at a thickness of generally 0.5 to 50 μm, particularly 1 to 40 μm. An alternative method of manufacturing the plastic bottles of the invention includes a parison of thermoplastic resin from which the bottle is to be made;
A latex or organic solvent solution of the above-mentioned copolymer is applied to a preform, sheet, film, etc., and then dried to form a coating layer, and this coating structure is then molded by the above-mentioned method to form a coated plastic container. Manufacture. The copolymer coating layer used in the present invention can withstand these treatments, and
It exhibits the excellent advantage of not losing adhesion to the substrate. When forming the coating layer, the copolymer may contain, if desired, a compounding agent known per se. For example, reinforcing agents, fillers, plasticizers, heat stabilizers,
One or more of antioxidants, ultraviolet absorbers, thickeners, thinners, antiblocking agents, lubricants, leveling agents, colorants, etc. are added to the copolymer according to known formulations. Can be mixed. Of course, additives such as pigments, antioxidants, antistatic agents, ultraviolet absorbers, and lubricants may be added to at least one of the melt-moldable moisture-resistant thermoplastic resin and the ethylene-vinyl alcohol copolymer, as desired. One or more of these may be added in a total amount of 0.001 to 5.0 parts per 100 parts by weight of the resin. For example, in order to reinforce this container, fiber reinforcing materials such as glass fiber, aromatic polyamide fiber, carbon fiber, bulb, cotton linter, etc., powder reinforcing materials such as carbon black and white carbon, glass flakes, and aluminum can be used. One or more types of flake-like reinforcing materials such as flakes are added to the thermoplastic resin.
It can be blended in a total amount of 2 to 150 parts by weight per 100 parts by weight, and for the purpose of increasing the amount, heavy to soft calcium carbonate, mica, talc, kaolin, gypsum,
Clay, barium sulfate, alumina powder, silica powder,
5 as a total amount of one or more types of magnesium carbonate etc. per 100 parts by weight of the thermoplastic resin.
There is no problem even if it is blended in an amount of 150 parts by weight according to a recipe known per se. The plastic container of the present invention takes advantage of the above-mentioned advantages and is useful as a lightweight plastic container for storing various foods, seasonings, beverages, medicines, cosmetics, agricultural chemicals, etc. over a long period of time. The invention is illustrated by the following example. Measurements of ultraviolet transmittance (UVT), oxygen permeability (Qo ₂ ), flavor test (FLR), and transparency characteristic (doc) described in each example were carried out according to the methods described below. (i) Ultraviolet transmittance (UVT): The body or bottom of the obtained container was cut into a predetermined size, and a recording spectrophotometer manufactured by Hitachi, Ltd. was used. As in the case of Figure 3, the wavelength is
Measurements were made over a wavelength range of 210 to 700 mμ.
The ultraviolet transmittance at 280 mμ (arrow in Figure 3) is expressed in UVT. (ii) Oxygen permeability (Qo ₂ ): After filling the empty container to be measured with 20 c.c. of water in advance, the container is replaced with nitrogen gas in a vacuum,
After sealing the mouth of the container with a rubber stopper and covering the contact surface between the mouth and the rubber stopper with epoxy adhesive, the container was placed in a constant temperature and humidity chamber at a temperature of 27°C and a humidity of 15% RH. After storage for a certain period of time, the concentration of oxygen permeated into the container was determined using a gas chromatograph, and the oxygen gas permeability (Qo ₂ ) was calculated according to the following formula. Results are average values of N=3. Here, m: Amount of nitrogen gas filled into the container [ml], t: Storage period in the hot tank [day], ct: Oxygen concentration in the container after t days [Vol%], A: Concentration of the container Effective surface area [m ² ], Op; oxygen gas partial pressure (=0.209) [atm]. (iii) Flavor test (FLR): Laminated containers with the above-mentioned polyvinylidene chloride resin applied to the inner or outer surfaces of the container, and laminate containers (container substrate) without the above-mentioned polyvinylidene chloride-based resin applied for comparison. Two types of containers were filled with distilled water, the mouths of which were sealed, and left at a temperature of 50°C for 3 days. Thereafter, a panel of 24 people tasted the distilled water and compared and judged the tasteless and less odor containers to be better. The numerical values in each table in Examples represent the number of panels judged to be good. (iv) Transparency characteristics (doc): 10 people (panel) for laminated containers with the polyvinylidene chloride resin applied to the outer or inner and outer surfaces of the containers and uncoated containers (container substrates) for comparison. First, show the two types of empty containers (unfilled containers) to be compared.
Pairwise comparisons were made using a visual judgment method, and participants were asked to select the container with the better appearance, such as transparency and gloss. Next, the two types of containers that were subjected to visual judgment were filled with tap water in which 1% by weight of Congo Red, a type of dye, was dissolved, and each filled container was shown to the same panel of 10 people as before, and the same visual judgment was performed. A pairwise comparison was conducted using the method, and the participants were asked to select a container with a better visibility of the contents (ie, a container with less cloudiness or heterochromatic appearance of the contents). In such a two-step visual judgment method, one panel member gives one point to a designated container, and through pairwise comparison, it is determined that there is "no difference" in the appearance or the perspective of the contents between the two types of containers. If it was, 0.5 points were given to both containers, and the total score for each of the two types of containers was calculated. The transparency characteristic (doc) was calculated using the following formula. doc=(B-A)+(C-D)/2N=(B-A)+(C-D)/2×10...(2) In the formula, N is the number of panel members (10 people in this case) represents. In addition, A, B, C, and D are shown in the following table (Table-
R _EF .) means the total score for each container (A+B=C+D=10 points).

[Table] In the above formula showing the degree of perspective characteristic (doc),
If the value of doc is a + (plus) sign, the "container-" is more likely to be "container--" depending on the filling of the contents.
The see-through properties of the contents are better than that of doc=＋
A value of 1.0 means that the effect is most pronounced. On the other hand, if the value of doc is a - (minus) sign, it means that the see-through characteristics of the contents are poor, and if doc = 0, even if the contents are filled, two types of containers (container - and This means that the see-through properties of the container (-) remained unchanged. Example 1 A moisture-resistant thermoplastic synthetic resin (5 and 6 in Figures 2-A to 2-C) that can be melt-extruded has a melt index (ASTM D1238) of 1.4.
g/10 min isotactic polypropylene as the inner and outer layers, and maleic anhydride modified polypropylene (Mitsubishi Yuka Co., Ltd. Model P-40B) as the adhesive layer, with an ethylene content of 40 mol% and a saponification degree of 99.
% saponified ethylene/vinyl acetate copolymer (ethylene-vinyl alcohol copolymer) as the middle layer (inner volume: 500 c.c.) was made using a known biaxial stretch blow molding method. It was molded (composition ratio: inner and outer layers: adhesive layer: intermediate layer = 50:0.5:1). Next, on the inner surface of the obtained laminated bolt substrate, 40 parts by weight of ethylene trichloride was added to 100 parts by weight of a total of 83% by weight of vinylidene chloride, 14% by weight of methoxyethyl methyl acrylate, and 3% by weight of methyl acrylate.
A polyvinylidene chloride resin latex (dispersion medium: water, solid content concentration: 50% by weight) having a composition ratio of parts by weight is applied by a known slush coating method,
After drying at 70℃ for 5 minutes using a perfect oven (explosion-proof type), dry at 48℃ in an air thermostat.
Aging (heat treatment) was performed for 24 hours. Then, a laminated bottle having a layered structure as shown in FIG. 2-A was obtained. The film thickness of the polyvinylidene chloride resin coated on the inner surface of the resulting container was 25 μm. Hereinafter, this laminated bolt will be referred to as A. In addition, the temperature of this polyvinylidene chloride resin at 20℃,
The oxygen permeability coefficient at 100%RH is 1.42×10 ^-14
cc·cm/cm ² ·sec·cmHg and water vapor permeability coefficient (JIS Z-0208) are 1.02×10 ⁻³ g·cm/m ² ·day. The ultraviolet transmittance (UTV) at a wavelength of 280 mn was determined for the obtained A bottle and the laminated bottle substrate (hereinafter referred to as nA) not coated with the polyvinylidene chloride resin for comparison according to the method described in the main text. ) and oxygen permeability (Qo ₂ ) measurement results are shown in Table 1. Table 2 shows the results of flavor test (FLR) measurements.

【table】

[Table] From Tables 2 and 3, by applying the polyvinylidene chloride resin to the laminated bottle substrate,
It is known that the barrier properties against ultraviolet rays (UVT) and oxygen (Qo ₂ ) are improved, and the flavor (FLR) is also significantly improved. Example 2 A moisture-resistant thermoplastic synthetic resin (5 and 6 in Figures 2-A to 2-C) that can be melt-extruded has a melt index (ASTM D-1238) of 0.3.
g/10min high-density polyethylene resin as the outer layer, and maleic anhydride-modified high-density polyethylene (manufactured by Mitsubishi Yuka Co., Ltd.: H-31B) as the adhesive layer, with an ethylene content of 30 mol% and a saponification degree of 99%. - A laminated wide-mouth container (cup, internal volume: 1000 c.c.) with a three-layer structure having a saponified vinyl acetate copolymer (ethylene/vinyl alcohol copolymer) as an inner layer was molded using a known vacuum forming method (configuration Ratio: Outer layer: Adhesive layer: Inner layer =
5:0.5:1). Next, a polyvinylidene chloride resin latex (dispersion medium: water, solid content concentration: 30% by weight) having a composition ratio of 95% by weight of vinylidene chloride and 5% by weight of acrylonitrile is applied to the outer surface of the obtained laminated cup.
was applied using a known dip coating method, dried at 50℃ for 55 minutes using a Perfect Oven (explosion-proof type), and then aged (heat treated) at 90℃ for 3 minutes in an air thermostat. . And the second
A laminated cup having a layer configuration as shown in Figure 1-B was obtained. The film thickness of the polyvinylidene chloride resin coated on the outer surface of the resulting container was 1.5 μm. Hereinafter, this laminated cup will be referred to as B. In addition, the temperature of this polyvinylidene chloride resin at 20℃,
The oxygen permeability coefficient at 100%RH is 1.20×10 ^-14
cc·cm/cm ² ·sec·cmHg and water vapor permeability coefficient (JIS Z-0208) are 0.85×10 ⁻³ g·cm/m ² ·day. The ultraviolet transmittance at a wavelength of 280 mμ (UVT ) and oxygen permeability (Qo ₂ ) measurement results are shown in Table 3. Furthermore, Table 4 shows the results of measuring the degree of perspective characteristic (doc).

【table】

[Table] Tables 3 and 4 show that by applying the polyvinylidene chloride resin to the laminated cup substrate, the barrier properties against ultraviolet rays (UVT) and oxygen (Qo ₂ ) are improved, and the transparency properties (doc) are also improved. It is known that this has been significantly improved. Example 3 Melt-extrudable moisture-resistant thermoplastic resin (second
-A to 5 and 6) in Figures 2-C, the melt index is 0.4g/10min, the density (ASTM
D-1505) is a saponified ethylene/vinyl acetate copolymer (ethylene/vinyl alcohol copolymer) with an ethylene content of 25 mol% and a saponification degree of 97%. ) and the low density polyethylene and ionomer (melt index: 1.5g/10min, ion type:
3-layer laminated tube (inner volume: 20c.c.) with a mixture of 70:20:10 (Na ⁺ ) as the middle layer
was molded using a known coextrusion blow molding method (component ratio:
Inner/outer layer: middle layer = 1:1). Next, the polyvinylidene chloride resin latex (dispersion medium: water, solid content concentration: 50% by weight) described in Example 1 was applied to the inner and outer surfaces of the obtained laminated tube by a known slush coating method or dip coating method. 40 minutes at 60℃ using a perfect oven.
After drying for 5 minutes, it was heated to 40℃ in an air thermostat for 5 minutes.
Aging (heat treatment) was performed for several days. Then, a laminated tube having a layered structure as shown in FIG. 2-C was obtained. The total film thickness of the polyvinylidene chloride resin coated on the inner and outer surfaces of the resulting container was 30 μm. Below, this laminated tube is C-
It is written as 1. Next, this C-1 tube was heated at 60℃ using a Sunshine type weatherometer manufactured by Suga Test Instruments Co., Ltd.
Irradiation was performed for 50 hours (irradiation energy = 1.2 ×
¹⁰⁷ joules/ ^m2 ). Below, this laminated tube is C-
It is written as 2. The obtained laminated tubes C-1 and C-2 and the laminated tube substrate (hereinafter referred to as nC) not coated with the polyvinylidene chloride resin for comparison were treated according to the method described in the text. Table 5 shows the measurement results of ultraviolet transmittance (UVT) and oxygen transmittance (Qo ₂ ) at a wavelength of 280 mμ. Also Flavor Test (FLR) and C
Tables 6 and 7 show the results of measurements of the fluoroscopic characteristics (doc) of the -2 tube and the nC tube, respectively.

【table】

【table】

[Table] From Tables 5, 6 and 7, by applying the polyvinylidene chloride resin to the laminated tube substrate,
The barrier properties against ultraviolet rays (UVT) and oxygen (Qo ₂ ) are improved, and the UV protection effect is particularly noticeable when treated with a weatherometer, and the flavor (FLR) and transparency properties are also significant. It is known that this has been improved. Next, each of the laminated tubes C-1, C-2, and nC was filled with commercially available soybean oil immediately after opening, and the mouth was sealed. These three types of filled tubes were left in an atmosphere of 1000 Lux for 3 months. Thereafter, for the soybean oil filled in each tube, the rate of change in absorbance at 470 mμ (=absorbance after standing/absorbance immediately after opening) was determined using a spectrophotometer. The rate of change in absorbance is 0.91 for soybean oil filled in C-1 tube, and 0.91 for soybean oil filled in C-2 tube.
0.99, nC tube 0.53, and the discoloration rate of the laminated tube coated with the polyvinylidene chloride resin was clearly smaller than the result of the tube substrate (nC). Example 4 As a moisture-resistant thermoplastic synthetic resin (5 and 6 in Figures 2-A to 2-C) that can be melt-extruded, polyvinyl chloride with an average degree of polymerization of 850 was used as the inner and outer layers, and the ethylene content was 48 mol%, saponification degree 99%
A 3-layer laminated bottle with a saponified ethylene/vinyl acetate copolymer (ethylene/vinyl alcohol copolymer) as the middle layer was molded using a known coextrusion method (component ratio: middle layer: inner and outer layers = 80:1). Next, on the outer surface of the obtained laminated bottle, 70% by weight of vinylidene chloride, 10% by weight of methyl acrylate,
A polyvinylidene chloride resin latex (dispersion medium: water, solid content concentration: 64% by weight) having a composition ratio of 20% by weight and glycidyl acrylate was applied by a known spray coating method, and a perfect oven was used. After drying at 100°C for 10 seconds, aging (heat treatment) was performed at 100°C for 15 seconds in an air constant temperature bath. A laminated bottle with a layered structure as shown in Figure 2-A (inner volume 300c.c.)
I got it. The film thickness of the polyvinylidene chloride resin coated on the outer surface of the resulting container was 18 μm. Hereinafter, this laminated bottle will be referred to as D-1. In addition, the temperature of this polyvinylidene chloride resin at 20℃,
The oxygen permeability coefficient at 100%RH is 2.49×10 ^-14
cc·cm/cm ² ·sec·cmHg and water vapor permeability coefficient (JIS Z-0208) are 1.76×10 ⁻³ g·cm/m ² ·day. Next, this D-1 bottle was irradiated using the same weatherometer as in Example 3 under the same conditions as in Example 3. This laminated bottle is shown below as D
It is written as -2. The obtained laminated bottles D-1 and D-2 and the laminated bottle substrate (hereinafter referred to as nD) not coated with the polyvinylidene chloride resin for comparison were treated according to the method described in the text. Table 8 shows the measurement results of ultraviolet transmittance (UVT) and oxygen transmittance (Qo ₂ ) at a wavelength of 350 mμ.

[Table] Next, fill these three types of laminated bottles with tap water to their full capacity, seal the mouth, and then heat the bottles at 50℃ and 10%RH.
It was left in an atmosphere for 21 days. Then reduce the amount of tap water filled in each bottle.
It was weighed using a top balance that can measure up to 10 mg, and the water loss was determined (=1-moisture content after standing/moisture content immediately after filling). The water loss is 0.0018 for D-1 bottle, D-
The water content of the laminated bottle substrate (nD) was 0.025, which was 0.025, which clearly showed a large water loss compared to the D-1 and D-2 bottles. Example 5 As a moisture-resistant thermoplastic synthetic resin (5 and 5' in Figures 2-A to 2-C) that can be melt-extruded, the inner layer was made of attack polystyrene with a melt index of 3.2, and the ethylene content was A two-layer laminated cup (inner volume: 280 c.c.) with an outer layer of saponified ethylene/vinyl acetate copolymer (ethylene/vinyl alcohol copolymer) with a saponification degree of 35 mol% and a saponification degree of 96%. It was molded by a known solid phase air pressure molding method (component ratio: inner layer: outer layer = 20:1). Next, on the inner surface of the obtained laminated cup, 80% by weight of vinylidene chloride, 10% by weight of methyl acrylate,
Total amount of acrylic acid monoglyceride 10% by weight 100
A polyvinylidene chloride resin latex (dispersion medium: water, solid content concentration: 22% by weight) having a composition ratio of 50 parts by weight of vinyl chloride to parts by weight was applied by a known slush coating method, and then placed in a perfect oven. It was dried for 2 minutes at 80°C. Such coating and drying operations were repeated three times. Then, aging (heat treatment) was performed at 30°C for 7 days in an air constant temperature bath. Then, a laminated cup (inner volume: 280
cc) obtained. The film thickness of the polyvinylidene chloride resin coated on the inner surface of the resulting container was 9.6 μm. Hereinafter, this laminated cup will be referred to as E. In addition, the temperature of this polyvinylidene chloride resin at 20℃,
The oxygen permeability coefficient at 100%RH is 6.80×10 ^-14
cc·cm/cm ² ·sec·cmHg and water vapor permeability coefficient (JIS Z-0208) are 2.96×10 ⁻³ g·cm/m ² ·day. The ultraviolet transmittance at a wavelength of 350 mμ (UVT ) and oxygen permeability (Qo ₂ ) measurement results are shown in Table 9. Table 10 also shows the results of flavor test (FLR) measurements.

【table】

[Table] Next, each cup of E and nE was filled with commercially available tomato puree immediately after opening, the mouth was sealed with a laminated film containing aluminum foil, and the cup was heated to 30°C and 80% RH. It was left at a location (1000 Lux) for 14 days. After that, the a value of each tomato puree filled in each cup was measured using a color difference meter, and the discoloration rate (= a value after standing / a value immediately after opening the can) was measured.
value) was calculated. The discoloration rate of the tomato puree filled in the E cup was 0.97, while the discoloration rate of the puree filled in the nE cup was 0.70. Furthermore, each of these tomato purees left to stand was tasted by the 24 panelists and they were asked to judge the flavor and taste. All 24 panelists answered that the tomato puree filled in E-cups had better flavor and taste.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a coated plastic container in the form of a bottle, and FIGS.
A cross-sectional view showing an enlarged portion of the wall of the bottle shown in the figure.
Fig. 3 is a diagram showing the relationship between wavelength and transmittance for the wall of a plastic container, and the reference numbers are 1...the entire bottle, 2...the peripheral wall of the bottle, 3...the mouth of the bottle, 4... ...Bottle bottom, 5, 6...
...Moisture-resistant thermoplastic resin that can be melt-molded, 7...Layer mainly composed of ethylene/vinyl alcohol copolymer, 8...Bottle substrate, 9,9'...vinylidene chloride/acrylic (methacrylic) copolymer Each coating layer is shown.

Claims (1)

[Scope of Claims] 1. A plastic comprising a melt-moldable moisture-resistant thermoplastic resin layer and a layer mainly composed of an ethylene-vinyl alcohol copolymer, and at least one surface of which is a moisture-resistant thermoplastic resin layer. (a) 99 to 70% by weight vinylidene chloride in a container substrate adjacent to the moisture-resistant thermoplastic resin layer; and (b)
1 to 30% by weight of the following formula, In the formula, R ₁ represents a hydrogen atom or a methyl group, and X represents a nitrile group or a formula, (In the formula, Y is an alkyloxy group, a hydroxyalkyloxy group, or a glycidyloxy group)
a group represented by, at least one monomer represented by: and (c) containing up to 50 parts by weight of chlorine, excluding vinylidene chloride, per 100 parts by weight of the total amount of the monomers (a) and (b). A copolymer consisting of at least one type of ethylenically unsaturated monomer, which has an oxygen permeability coefficient of 9×10 ^-14 cc・cm/cm ²・sec・cmHg or less and a water vapor permeability coefficient at 20°C and 100%RH. (JIS Z-0208) is 3×10 ^-3 g・
A plastic container with excellent preservability characterized by being provided with a coating layer of cm/m ² ·day or less. 2. The container according to claim 1, wherein the moisture-resistant thermoplastic resin is an olefin resin. 3 The ethylene-vinyl alcohol copolymer has an ethylene content of 20 to 80 mol% and a saponification degree of
The container according to claim 1, which is 90% or more ethylene-vinyl alcohol copolymer. 4. The container according to claim 1, wherein the plastic container substrate comprises inner and outer surface layers made of olefinic resin and an intermediate layer of ethylene-vinyl alcohol copolymer located between these layers. 5. The container of claim 1, wherein said plastic container substrate is a plastic bottle. 6. The container according to claim 5, wherein the plastic bottle has molecules oriented in one or two axes. 7. The container of claim 1, wherein said plastic container substrate is a plastic cup. 8. The container according to claim 7, wherein the plastic cup has molecular orientation in one or two axes. 9. Claim 1, wherein said plastic container substrate is an extrudable plastic tube container.
Containers listed in section. 10. The container of claim 1, wherein the coating layer has a thickness of 0.5 to 50 microns.