JPH06380B2 - Polyester multilayer container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a polyester multilayer container. More specifically, the present invention relates to a biaxially oriented polyester multilayer container having at least one layer made of polyester containing plate-like inert inorganic particles.

<Prior Art> Polyesters, particularly polyesters containing terephthalic acid as a main acid component, have been widely used as materials for fibers and films because of their excellent mechanical properties and chemical resistance, and have recently been attracting attention as containers for glass. .

However, when polyester is used as a packaging material for containers and the like, it is superior to polyethylene, polypropylene and the like, but the gas barrier property is not always sufficient as compared with glass and metal, and improvement thereof is desired.

As a method to improve the gas barrier property of polyester, a method of coating polyvinylidene chloride, a method of laminating polyvinyl alcohol, a method of blending organic substances such as caffeine and theopromine (RD230,029), and blending or laminating a special polyester such as polyethylene isophthalate Method (JP-A-59-64658, JP-A-59-3)
9547), and a method of blending or laminating metaxylylenediamine-adipic acid polyamide (MXD6 nylon) (JP-A-58-160,344, JP-A-57-123,0).
Various methods such as Japanese Patent No. 51) have been proposed. However, the method of using polyvinylidene chloride or MXD6 nylon has a problem of generating toxic gas when incinerated because it contains halogen or nitrogen atoms, and the method of using polyvinyl alcohol is injured during melt molding because polyvinyl alcohol is thermally weak. It is easy to get up and is affected by moisture. Further, the method using caffeine or the like may cause elution depending on the filling material of the container. The method using polyethylene isophthalate does not have such a problem, but in order to obtain a sufficient barrier property, it is necessary to blend or laminate a large amount, and there is a possibility that the physical properties of the container may deteriorate.

On the other hand, containers made of polyester containing inorganic particles such as glass fibers and talc are known. For example, Japanese Examined Shoko 55
No. 11136 discloses that glass flakes are treated with chromium or a silica-based treating agent and then added in an amount of 0.1 to 1% by weight. However, this container also has an insufficient gas barrier property. In JP-A-57-70154, 1 to 10 μm
A polyester container in which the inorganic particles of (1) are added to give a light transmittance of 30 to 80% and which has a ground glass appearance is known. Further, JP-A-58-20443 describes a high-grade glass-like polyester container using 0.1 to 30% by weight of glass granules other than the inner layer. All of these are intended to give a special container appearance, and nothing is said about gas barrier properties. In addition, JP-A-57-73045, 5
JP-A-8-20634 discloses a polyester container in which glass fibers having an aspect ratio of 3 or more are blended, and JP-A-58-20635 discloses a polyester container containing 0.1 to 30% by weight of glass particles having a particle diameter smaller than the wall thickness. ing. Further, in JP-A-56-2342, JP-A-56-21832 and JP-A-56-21833, kaolin, talc, sodium stearate, sodium benzoate, etc. are added in an amount of 0.002-0.5 weight. % Formulation is disclosed. Further, JP-A-57-207639 discloses a composition containing inorganic powder, organic acid salt and the like. All of these are intended to improve the crystallinity of polyester and improve the heat resistance and heat shrinkage resistance of the container, and there is no description regarding gas barrier properties. Also, JP-A-56-18
Japanese Patent No. 646 describes a composition containing silicon dioxide, which is intended to reduce aldehyde.
JP-A-58-20636 discloses that the thickness is 10 μm or less and the particle size is 1
0.1 to 30% by weight of plate-like glass powder of 0 mesh or less
A blended polyester container is disclosed.

The present inventors have studied a gas barrier property improving method capable of solving the above-mentioned drawbacks, and as a result, it has been found that the objective can be achieved if inorganic particles having a specific shape and size are blended with polyester. I found it.

<Object of the Invention> An object of the present invention is to provide a biaxially oriented polyester multilayer container having excellent gas barrier properties.

<Structure of the Invention> The present invention provides a plate-like inactive inorganic particle having an average particle size of 5 μm or less with an average particle size of 0.
A biaxially oriented polyester multi-layer container having at least one layer other than the innermost layer of a polyester containing 01 to 30% by weight and at least an innermost layer of a polyester not containing the inorganic particles.

In the present invention, the “container” refers to a hollow container such as a bottle or a can. These are molded into a planar shape or tubular shape or hollow shape with a bottom by extrusion molding or injection molding, and at least a part of them are stretched and oriented biaxially by compression molding, vacuum molding, blow molding or the like. can get. Among these, at least one layer other than the innermost layer of the two or more layers is composed of a polyester layer containing the plate-like inert inorganic particles.

In the present invention, the "polyester" is a polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component, and mainly a crystalline aromatic polyester such as polyethylene terephthalate or polyethylene-2,6-naphthalate. As a target, a part of terephthalic acid naphthalene-2,6-dicarboxylic acid or the like is partially substituted with aromatic dicarboxylic acid such as isophthalic acid, naphthalene-2,7-dicarboxylic acid, hexahydroterephthalic acid or hexahydroisophthalic acid. Aliphatic dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, p-β-hydroxyethoxybenzoic acid, other difunctional carboxylic acids such as oxyacids such as ε-oxycabroic acid, and / or ethylene glycol Part of, for example, diethylene glycol, tri Methylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, 1,1-cyclohexanedimethylol,
It may be a polyester substituted with other glycols such as 1,4-cyclohexanedimethylol. In addition, one or more polyfunctional compounds such as pentaerythritol, trimellitic acid, trimesic acid and the like or ester-forming derivatives thereof and / or one or more monofunctional compounds such as o-benzoylbenzoic acid may be copolymerized. Good. Further, if desired, any additive such as a colorant, a fluorescent whitening agent, a stabilizer, a UV absorber, an ether bond inhibitor, a flame retardant, an antistatic agent, etc. may be used.

The inert inorganic particles to be blended in at least one layer other than the innermost layer in the present invention need to be plate-shaped. Granular (spherical, ellipsoidal, spindle-shaped, tetrahedral, etc.), rod-shaped (needle-shaped, star-shaped, rod-shaped, tubular, thread-shaped, strip-shaped, etc.), amorphous, lump-shaped, etc. not compatible. If it has a plate shape, it may have a circular shape, an oval shape, or a triangular shape, a square shape, a rhombus shape, a short shape, a hexagonal shape, an octagonal shape, or the like. The following are illustrated as specific examples of these plate-like inert inorganic particles. Kaolins such as ditzkite, nacrite, kaolinite, anoxite; plates of halloysite; serpentine family such as risaldite, 6-layer serpentine, antigorite; montmorillonite minerals such as montmorillonite, sauconite, nontroite Knight,
Savonite, hectorite; vermiculite minerals, such as vermiculite; mica minerals, such as illite, sericite, glauconite; mechanical grinding (Jiyokratsiya,
Stamp mill, ball mill, cutter mill, eddy mill, micronizer, etc.) Al, Cu, Fe, P
b, Sn, Fe alloy; Ag, Co, by aqueous solution electrolysis method
Plate-shaped one of Cu, Fe, Ni, Sb, Sn, etc .; M
g Fine particles; Al ₂ O ₃ , Al ₂ O ₃ hydrate, Fe
₂ O ₃ , ZnO, Cr ₂ O ₃ , PbO, Co (O
H) ₂ , Pb (OH) ₄ , CaWO ₃ , CaCu ₄ Cl
O, AgBr, AgI, BaSO ₄ , PbI ₂ , MgC
O ₃ (basic), synthetic powder particles such as BaSO _4, etc. Among these, kaolin group, serpentine group, montmorillonite mineral, vermiculite mineral, and mica mineral are preferable, and kaolinite, dateskite, vermiculite,
Montmorillonite and sericite are preferred.

The plate-like inert inorganic particles need to have an average particle size of 5 μm or less. If it is 5 μm or more, the surface flatness of the molded product is deteriorated. It is preferably 2 μm or less, particularly preferably 1 μm or less. Here, the average particle size is 50 of all measured particles.
It means the "equivalent spherical diameter" of a particle in% by weight.
By "equivalent sphere diameter" is meant the diameter of an imaginary sphere having the same volume as the particle, which can be calculated from electron micrographs of the particle or measurements by conventional sedimentation methods.

With respect to the particle size distribution of the inert inorganic particles having an average particle size of 5 μm or less, it is more preferable that almost no coarse particles having a particle size of about 10 μm or more are contained and a fine distribution has a sharp distribution.

In the present invention, the content of the inert inorganic particles in the polyester layer containing the plate-like inert inorganic particles is 0.01 to 30.
%, Preferably 0.02 to 10% by weight. 0.005 to 15% by weight, preferably 0.0
It is 1 to 5% by weight. If the content of the inorganic particles is less than the lower limit, the effect of improving the gas barrier property is small, and if it exceeds the upper limit, not only the effect of the gas barrier property is saturated, but also the bottle strength decreases. To obtain transparency, the content is controlled to 0.3% by weight or less based on the whole.

In the present invention, the method for distributing the plate-like inert inorganic particles to the polyester is preferably before the middle stage of polyester polymerization, and particularly in the middle stage of esterification or transesterification (internal temperature of 160 to 20).
(Around 0 ° C.) is preferable. This is important from the viewpoint of preventing aggregation of inorganic particles during addition. However, even after the middle stage of esterification or transesterification and before the middle stage of polymerization, heating the inorganic particle slurry to 100 to 200 [deg.] C. and adding it can sufficiently achieve the purpose. The method of adding after the middle stage of the polymerization or directly blending with the chip after the completion of the polymerization of the polyester and before the molding is easy to introduce voids, and it is difficult to obtain transparency, but the object can be achieved.

As a method of adding the inorganic particles to the polyester production process, a method of adding as a glycol slurry of 0.5 to 20% by weight is preferable. Inorganic particles may be added to polyester at a high concentration by the above-mentioned method, polymerized, and this may be used as a master batch to be diluted with a separately produced polyester containing no inorganic particles so as to obtain a desired particle amount.

In the present invention, the layer containing the plate-shaped inorganic particles is the innermost layer, and when the contents are filled, it cannot be said that there is no risk that it will be partially dissolved and extracted. Use as the innermost layer of should be avoided. Therefore, the innermost layer is a layer made of polyester containing no inorganic particles. A three-layer structure in which a layer made of polyester containing no inorganic particles is sandwiched between layers made of polyester containing inorganic particles, or a multilayer having more layers may be used. Since it is composed of multiple layers made of the same polyester, the adhesion between layers is good and there is no risk of delamination.

A multilayer container is first formed into a preform, pipe, sheet, etc. by multilayer injection or extrusion, and then heated to a temperature above the second-order transition temperature of polyester and below the melting point (after bottoming in some cases), and then biaxially oriented blow. A biaxially oriented container is obtained by rolling in a metal mold or deep drawing by vacuum forming.

<Effects of the Invention> The multi-layer container of the present invention has a characteristic that the gas barrier property is 10% or more higher than that of a polyester container containing no inorganic particles, and can be sufficiently used as a container such as a carbonated beverage or a beer container which is required to have a gas barrier property. .

<Examples> The present invention will be specifically described with reference to Examples below. All "parts" in the examples represent parts by weight, and each item was measured by the following measuring methods.

O Intrinsic viscosity [η]: Calculated from the solution viscosity of the polymer orthochlorophenol solution at 35 ° C.

○ Average particle size of inert solid fine particles: CP-50 type Centrifugal Particle Size An manufactured by Shimadzu Corporation
It was measured using an alyser. The particle size corresponding to 50 mass percent is read from the cumulative curve of the particles of each particle size and their abundance calculated based on the obtained centrifugal sedimentation curve,
This value was defined as the average particle size (see Book "Particle Size Measurement Technology", Nikkan Kogyo Shimbun, 1975, pages 242 to 247).

Gas barrier property: A 30 mmφ sample was cut out from the molded product, and the permeability coefficient of CO ₂ gas was measured at 30 ° C. using a gas permeability measuring device K-315N-03 manufactured by Rika Seiki Co., Ltd.

Examples 1 to 9, Comparative Examples 1 to 7 100 parts of dimethyl terephthalate, ethylene glycol 7
1 part of 0 parts and 0.03 parts of manganese acetate tetrahydrate were put into the reactor.
The transesterification reaction was carried out at 40 to 240 ° C.

On the other hand, kaolinite with an average particle size of 0.7μ was put in ethylene glycol and treated with a homogenizer, a sand grinder and a decanter to obtain kaolinite with an average particle size of 0.65μ.
A 0 wt% ethylene glycol slurry was prepared.

During the transesterification reaction, when the internal temperature reached 170 ° C., this ethylene glycol slurry was added so that the amount of kaolinite added was as shown in Table 1. Further reaction,
Orthophosphoric acid 0.015 at the end of transesterification
And 0.012 parts of germanium dioxide were added and polycondensation reaction was carried out to obtain a polyester having an intrinsic viscosity of 0.65.
Further, this was subjected to solid phase polymerization in an inert gas stream at 200 ° C. to finally obtain a polymer (A) having an intrinsic viscosity of 0.75. On the other hand, Kaolinite-free polymer B was obtained in the same manner.

After drying both polymers, using an injection molding machine at a cylinder temperature of 280 ° C., A is an intermediate layer and B is an inner layer and an outer layer (inner layer: intermediate layer: outer layer = 3: 4: 3), weight 49 g, length 176.
A cylindrical bottomed parison with a thickness of 3.5 mm and a thickness of 3.5 mm was molded. At this time, the preform mold was cooled to 10 ° C. with cold water.
Then, the Paxson was reheated to an internal temperature of 90 to 105 ° C. and then biaxially stretched and blown to a height of 270 m.
m, the diameter of the body is 80 to 90 mm, and the average thickness of the body is 0.3
A bottle with an internal volume of 1 of 5 mm was obtained. (Area draw ratio of body: 10 times) Table 1 shows the physical properties of this bottle.

Example 5 An ethylene glycol slurry of kaolinite at room temperature was added at the final stage of transesterification (internal temperature: 240 ° C).

In Example 6, the addition time is the same as in Example 5, but an ethylene glycol slurry of kaolinite is heated to 150 ° C. and added.

Further, in Example 7, during the production of the polymer, the amount of kaolinite added was 15% by weight to prepare a master batch, which was molded by diluting and blending it 10 times with polyethylene terephthalate without additives before bottle molding.

In Example 8, additive-free polyethylene terephthalate was blended with kaolinite as a powder in an untreated state in a tumbler of 1.5 wt% and molded.

In Example 9 and later, inorganic particles other than kaolinite were used in Example 3
It is treated and added in the same manner as above, made into a polymer, and further molded into a bottle.

Example 12, Comparative Example 5 Polymer A and polymer B of Example 3 were used to coextrude a 300 μ film of A layer / B layer 1/1 with a coextruder having a cylinder temperature of 280 ° C. 9 of this film
It was heated to 0 ° C. and compression-molded in a cup-shaped mold so that the layer B was on the inside, to form a cup having a diameter of 100 mmφ, a bottom portion of 50 mmφ, and a height of 50 mm. The CO ₂ permeation coefficient of the body of this molded product was 14 cm ³ · cm / cm ² · sec · cmHg.

However, the same shape of CO ₂ consisting of polymer B alone
The transmission coefficient was 16 cm ³ · cm / cm ² · sec · cmHg.

Claims (2)

[Claims] 1. A plate-like inert inorganic particle having an average particle size of 5 μm or less
A biaxially oriented polyester multi-layer container in which a layer made of polyester containing 0.01 to 30% by weight is at least one layer other than the innermost layer and a layer made of polyester not containing the inorganic particles is at least the innermost layer. 2. The biaxially oriented polyester multilayer container according to claim 1, wherein the plate-like inert inorganic particles are selected from the group consisting of kaolin group, serpentine group, montmorillonite mineral, vermiculite mineral and mica mineral.