JP2000255540A - Repeatedly used multi-layer container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layer container keeping its transparency even if the container is washed or cleaned with hot water or alkaline solution during its repetitive use. SOLUTION: An inner layer (A) of a container is comprised of thermoplastic polyester (A) in which its major repetitive unit is ethylene naphthalate. The outside part of the inner layer (A) has a skin layer (B) comprised of at least one kind of thermoplastic resin (B) selected from the group consisting of a thermoplastic acrylic resin, a polyacrylate resin and a polyester resin of which glass transition temperature is at least 85 deg.C and not containing an ethylene naphthalate unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a multilayer container used repeatedly. More specifically, the present invention relates to a multilayer container having an inner layer made of ethylene naphthalate polyester and a skin layer made of another resin, having excellent transparency and being repeatedly used.

[0002]

2. Description of the Related Art When a container made of polyester filled with beverages such as water, carbonated beverages, beer, wine, etc. is collected and shipped, and the shape of the container is retained and reused again (repeated use), it is usually collected. The used container is washed with an aqueous alkali solution such as sodium hydroxide. For example, polyethylene terephthalate containers were collected from the market,
After being alkali-washed, beverages and the like are filled again and shipped to the market. However, this collection and reuse may be about 10 times. The number of reuses is determined by the mechanical properties of the container, the presence or absence of damage, the degree of the damage, polymer deterioration, etc., and causes of this deterioration include ultraviolet light deterioration due to exposure to sunlight, deterioration due to alkali cleaning, and the like. It is.
However, polyethylene terephthalate containers are 10
In the case of recovery and reuse about once, ultraviolet light deterioration and alkali deterioration are not a problem and have not become apparent.

In recent years, polyethylene terephthalate (PE)
T) Polyethylene as a polymer with better mechanical properties, thermal properties and less flavor carryover
Attention has been paid to 2,6-naphthalate (PEN), and a PEN container as a recovery and reuse container is being studied. This P
It is expected that EN containers can increase the number of times of collection and reuse.

However, in the development of a PEN container, the recovered PEN container is washed with an alkali, for example, 50%.
It was found that the transparency was reduced as the alkali washing was performed with a 1 to 6% aqueous sodium hydroxide solution heated to ９５95 ° C. In addition, this decrease in transparency
It became clear that the greater the number of recycles in which the PEN containers collected from the market were washed with alkali and reused, the more remarkable it became.

[0005]

As a result of intensive studies to solve this problem, the present inventor has found that the surface of a PEN container is deteriorated by ultraviolet rays during distribution on the market and during storage after recovery. It has been found that such a portion is easily peeled off by washing with an alkaline aqueous solution, and that the deteriorated peeling becomes remarkable by repeating the recycling, thereby lowering the transparency.
On the other hand, the existence of such a problem in PET containers is not apparent because PET has excellent weather resistance compared to PEN, and has a low washing temperature when repeatedly used, and is deteriorated by ultraviolet light when recovered and reused about 10 times. And alkali degradation was found to be small. The inventors have found a multilayer container which suppresses deterioration of the outer surface of the PEN container due to ultraviolet rays, suppresses erosion due to washing with alkali or the like, and suppresses a decrease in transparency due to repeated use, and completed the present invention. The purpose of the present invention is
An object of the present invention is to provide a container having good transparency even when used repeatedly.

[0006]

According to the present invention, it is an object of the present invention to provide a container wherein the inner layer (A) comprises a thermoplastic polyester (A) whose main repeating unit is ethylene naphthalate. At least one selected from the group consisting of a thermoplastic acrylic resin, a polyolefin resin, a polycarbonate resin, a polyarylate resin, and a polyester resin having a glass transition temperature of 85 ° C. or more and containing no ethylene naphthalate unit. Kinds of thermoplastic resin
This is achieved by a repeatedly used multilayer container having a skin layer (B) consisting of (B). In a preferred embodiment of the multilayer container, the skin layer contains an ultraviolet absorber.

Hereinafter, the present invention will be described. The thermoplastic polyester (A) forming the inner layer (A) of the multilayer container in the present invention is a polyester whose main repeating unit is composed of ethylene naphthalate, preferably a polyester whose main repeating unit is composed of ethylene-2,6-naphthalate. It is. Here, "main" means that the content is more than 80 mol%, preferably more than 85 mol% of all the repeating units. Therefore, other components of 20 mol% or less may be copolymerized, or may be contained as a mixture. For example, in the case of a polyethylene-2,6-naphthalate copolymer, a part (20 mol% or less) of the 2,6-naphthalenedicarboxylic acid component is converted to 2,7-, 1,5-, 1,7-.
Other isomers of naphthalenedicarboxylic acid, or other aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfondicarboxylic acid, etc., hexahydroterephthalic acid, Alicyclic dicarboxylic acids such as hexahydroisophthalic acid,
Aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, p-β-hydroxyethoxybenzoic acid,
It may be replaced by another bifunctional carboxylic acid such as an oxyacid such as ε-oxycaproic acid. Further, a part (20 mol% or less) of the ethylene glycol component may be used, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, 1,1-cyclohexanedimethanol, 1,4. -Cyclohexanedimethanol, 2,2-bis (4'-β-hydroxyphenyl) propane, bis (4'-β-hydroxyethoxyphenyl) sulfonic acid, etc. Good.

[0008] The polyester (A) can be produced according to a known method. For example, polyethylene
The production of 2,6-naphthalate (PEN) begins with 2,2
6-Naphthalenedicarboxylic acid or its ester-forming derivative (preferably dimethyl ester) and ethylene glycol are subjected to esterification or transesterification under heating. At that time, as a transesterification catalyst, cobalt,
It is preferable to use a manganese, calcium, magnesium, titanium compound or the like. Subsequently, a polycondensation reaction is performed under heating and vacuum in the presence of germanium, antimony, a titanium catalyst, and a phosphorus compound to obtain a polymer (PEN). The cobalt, manganese, calcium, magnesium, and titanium compounds are compounds conventionally known as transesterification catalysts, for example, cobalt acetate, manganese acetate, calcium acetate, lower fatty acid salts such as magnesium acetate, and chlorides such as cobalt chloride. Are used. As the titanium compound, for example, titanium oxide, titanium trimellitate, or the like is used. In addition, as this phosphorus compound,
Inorganic phosphoric acid such as orthophosphoric acid, hypophosphorous acid and phosphorous acid and organic phosphoric acid such as trimethyl phosphate are preferably used. Then, if desired, the polymer may be formed into chips or pellets and subjected to solid-phase polymerization according to a conventional method.
In order to obtain a polymer having a high degree of polymerization, it is preferable to carry out solid phase polymerization. This solid-phase polymerization also has the effect of reducing the amount of acetaldehyde and oligomer in the polymer. Polymer intrinsic viscosity (trichlorophenol 2
(A mixed solvent of 3 parts by weight of phenol and 3 parts by weight of phenol at 25 ° C.) is preferably 0.55 or more, more preferably 0.60 or more. The upper limit depends on the characteristics and moldability of the container, but is preferably 0.90, more preferably 0.80.

The multilayer container used repeatedly according to the present invention comprises a thermoplastic acrylic resin, a polyolefin resin, a polycarbonate resin on the outside of the inner layer (A).
It has a skin layer (B) made of at least one thermoplastic resin (B) selected from the group consisting of a polyarylate-based resin and a polyester-based resin having a glass transition temperature of 85 ° C. or higher and containing no ethylene naphthalate unit. .

The thermoplastic acrylic resin is preferably a homopolymer or a copolymer having a repeating unit of methyl methacrylate as a main component. In the copolymer, as components that can be copolymerized with methyl methacrylate, methyl acrylate, ethyl acrylate,
Butyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, 2-hydroxypropyl acrylate, n-propyl acrylate, n-tetradecyl acrylate, n-hexadecyl acrylate, lauryl acrylate, cyclohexyl acrylate, glycidyl acrylate Acrylic esters such as esters are preferred. 50 mol% as the ratio of the methyl methacrylate component
Above, more preferably 60 mol% or more.

Preferred examples of the polyolefin resin include homopolymers and copolymers having a repeating unit composed of α-olefins such as polyethylene and polypropylene as a main component. Examples thereof include homopolymers of propylene, homopolymers of ethylene, and ethylene. Or a random copolymer obtained by copolymerizing a polymer with another α-olefin (eg, propylene, butene-1, etc.), specifically, a copolymer of ethylene and an α-olefin having 3 or more carbon atoms (eg, ethylene / propylene) Copolymer, ethylene / butene-1 copolymer, etc.), ethylene, a copolymer comprising an α-olefin having 3 or more carbon atoms and a non-conjugated diene (for example, ethylene / propylene / 1,
4-hexadiene copolymer, ethylene / propylene / dicyclopentadiene copolymer, ethylene / propylene /
Ethylidene norbornene copolymer).
These can be used alone or in combination of two or more. Preferred polyolefin-based copolymers include a polypropylene homopolymer, a polyethylene homopolymer, and a copolymer of ethylene and an α-olefin having 3 or more carbon atoms having an ethylene content of 50 mol% or more (for example, ethylene / propylene copolymer, ethylene / Butene-1 copolymer etc.)
Is mentioned.

Examples of the dihydroxy compound component constituting the polycarbonate resin include hydroquinone, resorcinol, bis (hydroxyphenyl) alkanes, bis (hydroxyphenyl) cycloalkanes, bis (hydroxyphenyl) ethers, and bis (hydroxyphenyl). ) Ketones, bis (hydroxyphenyl) sulfoxides, bis (hydroxyphenyl) sulfones, and 2,2-bis (hydroxyphenyl) diisopropylbenzenes. More specifically, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 1,1-bis (4
-Hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, hydroxybenzophenone, 4,4 ′
-Sulfonyldiphenol and the like. Most preferred is 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

The polyarylate resin is a wholly aromatic polyester obtained by polymerizing an aromatic diol, an aromatic dicarboxylic acid or the like, or a derivative thereof. Specifically, 4,4'-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-
Dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,2-bis (4-hydroxyphenyl) propane and 4,4′-
At least one selected from dihydroxydiphenyl ether as a component, and terephthalic acid, isophthalic acid, 4,4′-diphenylcarboxylic acid as a dicarboxylic acid,
At least one component selected from 1,2-bis (phenoxy) ethane-4,4′-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid and diphenyletherdicarboxylic acid Is preferred. In addition, aliphatic and alicyclic dicarboxylic acids / diols may be copolymerized within a range not to impair the object of the present invention.

The polyester resin containing no ethylene naphthalate unit and having a glass transition temperature of 85 ° C. or higher is a copolymer or a blend. In the copolymer of the polyester resin, the dicarboxylic acid component is terephthalic acid, isophthalic acid, phenylindanedicarboxylic acid, 4,4′-diphenylcarboxylic acid,
-Bis (phenoxy) ethane-4,4'-dicarboxylic acid, wherein the diol component is an ethylene oxide adduct of fluorenes, specifically,
Selected from 9-bis (4-hydroxyethoxyphenyl) fluorene, 9,9-bis (4-hydroxypropoxyphenyl) fluorene, 9,9-bis (4-hydroxybutoxyphenyl) fluorene, and 1,4-cyclohexynesandimethanol Preferred are copolymers composed of at least one selected from ethylene glycol, propylene glycol and butanediol. Preferred blends include blends of these copolymers, polyethylene terephthalate, cyclohexane dimethanol copolymerized polyethylene terephthalate, and the like.

Further, the skin layer (B) may comprise the thermoplastic acrylic resin, polyolefin resin, polycarbonate resin, or the like, as long as the object of the present invention is not impaired.
A blend of two or more selected from a polyarylate-based resin and a polyester-based resin containing no ethylene naphthalate unit and having a glass transition temperature of 85 ° C. or higher, more preferably a thermoplastic acrylic resin, a polycarbonate-based resin, and a polyarylate It may be a blend of two or more selected from polyester resins containing no resin and ethylene naphthalate units and having a glass transition temperature of 85 ° C. or higher. These thermoplastic resins and their blends have melt moldability when molding preforms (precursors of bottles) and sheets and thermoformability or blow moldability when molding into containers. Although the range is different, it has a molecular weight of about 10,000 to 500,000.

In the present invention, the skin layer (B) may and preferably contains an ultraviolet absorber. As the ultraviolet absorber, it is preferable to use one or more selected from the group consisting of a benzotriazole-based ultraviolet absorber, a triazine-based ultraviolet absorber, and a benzoxazinone-based ultraviolet absorber.

Examples of the benzotriazole-based ultraviolet absorber (compound) include 2- (5-methyl-2-hydroxyphenyl) benzotriazole and 2- [2-hydroxy-3,5-bis (α, α'-). Dimethylbenzyl) phenyl] benzotriazole, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- (2Hbenzotriazol-2-yl)- 4- (1,1,3,3,
-Tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methylphenol,
2- (2H-benzotriazol-2-yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazol-2-yl) 4,6-di-t-amylphenol,
2- (2H-benzotriazol-2-yl) -4-t
-Butylphenol, 2- (2'-hydroxy-3'-
t-butyl-5'-methylphenyl) -5 chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5-di-t-butylphenyl) -5-chlorobenzotriazole, 6- (2-benzotriazolyl) L) -4-t-octyl-6'-t-butyl-4'-methyl-2,3-methylenebisphenol.

Examples of the benzoxazinone-based ultraviolet absorbers (compounds) include 2,2'-p-phenylenebis (3,1-oxazin-4-one) and 2-p-nitrophenyl-3,1- Benzoxazin-4-one, 2
-(2-Naphthyl) -3,1-benzoxazine-4-
ON, 2,2'-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-(2,6-naphthylene) bis (3,1-benzoxazin-4-one), etc. Can be mentioned.

The triazine-based ultraviolet absorber (compound)
For example, 2- (4,6-diphenyl-1,3,3)
5-triazin-2-yl) -5- (hexyl) oxyphenol and the like.

Among these ultraviolet absorbers (compounds), compounds having a large absorption intensity at 260 to 370 nm in an absorption region related to the degradation of polyethylene-2,6-naphthalate are preferred. More specifically, 2,2′-p-phenylenebis (3,1-oxazin-4-one), 2-
(4,6-diphenyl-1,3,5-triazine-2-
Yl) -5- (hexyl) oxyphenol, 2- (5
-Methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α'-
Dimethylbenzyl) phenyl] benzotriazole is preferred.

The amount ratio of the thermoplastic resin and the ultraviolet absorber forming the skin layer (B) is 0.01 to 10 parts by weight, preferably 0.05 to 10 parts by weight, per 100 parts by weight of the resin.
It is preferably from 5 to 5 parts by weight. When this amount exceeds 10 parts by weight, the ultraviolet absorbent is easily eluted, while
When the amount is less than the weight part, the ultraviolet absorbing ability is insufficient, and the effect of preventing the ethylene naphthalate-based polyester resin constituting the inner layer from deteriorating by ultraviolet light is small, which is not preferable.

The thickness of the skin layer (B) in the present invention is as follows:
0.5 to 100 μm is preferable, and 1 to 1 is more preferable.
50 μm. This skin layer (B) prevents the innermost layer of the ethylene naphthalate polyester resin from being exposed to ultraviolet rays or being eroded by alkali during use or (collection) storage of the container. Having
At the time of use or (recovery) storage, at least the ethylene naphthalate-based polyester resin constituting the inner layer of the container is exposed to ultraviolet rays, and has an effect of preventing ultraviolet ray deterioration. Although the thickness of the container inner layer (A) varies depending on the size and use of the container, it is usually preferably 0.15 to 1.0 mm, more preferably 0.25 to 0.6 mm in terms of the thickness of the body. If desired, another resin layer may be provided inside the inner layer, or another resin layer may be provided between the inner layer and the skin layer.

The multilayer container of the present invention can be produced by a known method using the above-mentioned thermoplastic resin.
For example, the preform can be molded and manufactured by a method such as performing orientation stretching blow after molding with a two-color molding machine. Further, after forming a sheet by co-extrusion molding by a T-die method, an inflation method or the like, it can be formed into a container such as a tray or a deep drawing cup by a thermoforming method such as compression molding or vacuum molding. As the container, a beverage bottle is most preferable, but a container for other uses may be used.

The multilayer container in the present invention is washed each time it is collected and reused. This washing is preferably carried out by washing with warm water or an aqueous alkaline solution. This temperature is preferably in the range of 50 ° C to 95 ° C, more preferably 65 to 95 ° C. If the temperature is low, the cleaning and sterilizing effects cannot be expected, while if the temperature is too high, the container will be thermally deformed. As the alkali, sodium hydroxide is usually used, and its concentration is in the range of 1 to 6%.

The washing of the container in the present invention is not particularly limited as long as the washing solution, preferably heated water or an aqueous alkali solution, comes into contact with the container, but it is preferable to immerse the container in the washing solution described above. Most preferred. In some cases, for example, a heated aqueous solution can be injected into the container. After the washing with the alkaline aqueous solution, washing with water or warm water is further performed. The temperature of the hot water is preferably 95 ° C. or less. The washing with water or hot water may be performed to such an extent that the alkaline aqueous solution can be sufficiently washed away.

Although the multilayer container of the present invention can be used repeatedly, the haze of the container body after repeating 15 times is 15%.
Or less, more preferably 10% or less. If it exceeds 15%, transparency is undesirably reduced.

In the case of ordinary repetitive use, the container is irradiated with ultraviolet rays (usually exposed to sunlight). However, the amount of ultraviolet light received in one repetition is in the wavelength region of 310 nm to 400 nm. , 500mJ / cm ² -90,000mJ
/ Cm ² is estimated.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The characteristics in the examples were measured by the following methods. (1) Haze One body part of the bottle (thickness: about 300 μm) was set in a turbidimeter and measured. (2) Illuminance of ultraviolet rays The illuminance of ultraviolet rays (310 to 400 nm) is MINOLT.
It measured with the UV intensity meter UM-10 made from A (light-receiving part UM-360).

[Embodiments 1 to 7] Preparation of polymer for inner layer (A) 2,6-naphthalenedicarboxylic acid dimethyl ester 10
0 parts by weight and 70 parts by weight of ethylene glycol were mixed with calcium acetate and magnesium acetate as transesterification catalysts, and methanol produced as a by-product was distilled out of the system.
The ester exchange reaction was carried out while heating to ℃ C, and at the stage when methanol was almost completely distilled off, germanium acetate was added as a polymerization catalyst, and subsequently trimethyl phosphate was added as a stabilizer to terminate the transesterification reaction. . Next, the reaction product was subjected to a polycondensation reaction under high temperature and high vacuum to obtain a prepolymer having an intrinsic viscosity of 0.55. This prepolymer was made into a strand type chip, and further subjected to solid phase polymerization under heating vacuum to obtain an intrinsic viscosity (a mixed solvent of 2 parts by weight of trichlorophenol and 3 parts by weight of phenol, 25
C) 0.65 solid-state polymerized polymer was obtained.

2. Molding of Bottle A preform was injection-molded using the solid-state polymerized polymer obtained in 1 above, and a resin layer (B) for forming a skin layer shown in Table 2 below was injection-molded outside the preform. Subsequently, the preform having a two-layer structure was heated and oriented blown to form a bottle. The preform was molded using a two-color molding machine manufactured by Nissei Plastics Industry (cylinder setting: 295 ° C,
Screw rotation speed 100 rpm, molding cycle 45 sec
c) and the average body thickness of the preform is 4.4 mm;
The weight was about 56 g. The bottle is KRUPP CORPOPL
The bottle was molded using LB01 manufactured by AST, and the bottle had an inner volume of about 1.0 L (liter) and an average body thickness of 300 μm.

[0031]

[Table 1]

3. 1. UV irradiation and cleaning The body of the bottle is irradiated with ultraviolet light (xenon tester; Shimadzu xenon tester XW-150), then washed with a 1.8% NaOH aqueous solution at 75 ° C. for 9 minutes by an immersion method, further washed with water, and dried. did. Repeat the operation from UV irradiation to drying 15 times, 4 × 4c from the bottle body
An m-square sample was cut out at three points, the haze was measured, and the average value was taken as the haze value.

[0033]

[Table 2]

[0034]

According to the present invention, the polyester resin multilayer container can be used repeatedly without deteriorating the transparency.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 23/00 C08L 23/00 33/00 33/00 67/00 67/00 69/00 69/00 // B29L 9 : 00 (72) Inventor Hiroki Nagano 77 Kitayoshida-cho, Matsuyama-shi, Ehime Pref. AG03 AG07 AH55 AR06 AR20 LB01 LB22 LG01 4J002 BB03X BB05X BB12X BB14X BB15X BG06X CF08W CF16X CG01X CG02X EU176 EU236 FD056 GG01

Claims (3)

[Claims] 1. An inner layer (A) of a container is made of a thermoplastic polyester (A) whose main repeating unit is ethylene naphthalate, and a thermoplastic acrylic resin, a polyolefin resin, a polycarbonate resin is provided outside the layer (A). A skin layer (B) made of at least one thermoplastic resin (B) selected from the group consisting of a resin, a polyarylate-based resin and a polyester-based resin having a glass transition temperature of 85 ° C. or higher and containing no ethylene naphthalate unit. A multilayer container which is used repeatedly, comprising: 2. The multilayer container according to claim 1, wherein the haze of the body of the container after being used repeatedly 15 times is 15% or less. 3. The method according to claim 1, wherein the skin layer (B) contains at least one member selected from the group consisting of a benzotriazole-based ultraviolet absorber, a triazine-based ultraviolet absorber and a benzoxazinone-based ultraviolet absorber. Multilayer container.