JPS59184627A - Manufacture of bottle made of multilayer orientation polypropylene - Google Patents

Abstract

PURPOSE:To improve gas barrier peculiarity, by a method wherein resin having gas barrier peculiarity turned into a solution or emulsion is coated on a primary preform of polypropylene, and orientation hollow molding of a multilayer preform is obtained by making injection molding of the polypropylene. CONSTITUTION:A primary preform 11 is immersed into a coating pot 13, a solution of adhesive resin or latex 14 is applied to the external surface of the primary preform and a solvent or water is removed by drying it. Then the primary preform is transferred to a resin coating pot having gas barrier peculiarity, solution of resin having gas barrier peculiarity or latex is applied to a coating surface of the preform to which an adhesive agent is applied and dried. A temperature of the coated preform is adjusted to the temperature under which whitening is made not to generate though it possesses elastically deformable character, the preform whose temperature has adjusted is set to metal molds 16, 17 of injection molding, injection molding of polypropylene is made and multilayer preform is molded. Then an orientation bottle is manufactured through orientation in the axial direction and blow orientation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a multilayer oriented polypropylene bottle, and more particularly to a method for producing a multilayer oriented polypropylene bottle, which is characterized by the production of a multilayer polypropylene preform for stretching.

It is known that when polypropylene, which can be oriented by stretching, is stretched 2@1tIL, its appearance such as transparency, mechanical properties such as rigidity, dimensional stability, etc. are improved, and this biaxial stretching is used to form containers. This has also been done for a long time. Of this container! ! ! In the process of forming the polypropylene into a bottomless or bottomed cylindrical body, that is, a preform, by extrusion molding or injection molding, the preform is stretched in the axial direction and the preform is stretched in the circumferential direction. By simultaneously or sequentially carrying out the operations of inflating and inflating by blowing fluid, a molded container is formed in which the container wall has molecules oriented in biaxial directions.

Although this biaxially stretched molded container is excellent in transparency, rigidity, impact resistance, dimensional stability, etc. as described above, it is still not fully satisfactory in terms of gas barrier properties. For example, even after stretching, biaxially stretchable crystalline polypropylene such as polypropylene homopolymer and propylene copolymer has a higher gas barrier property than high gas barrier resins such as saponified ethylene-vinyl acetate copolymer and vinylidene chloride resin. 6, the oxygen permeability coefficient is an order of magnitude higher; on the other hand,
There is a problem in that high gas barrier resins are generally difficult to be biaxially stretched.

Gas barrier for biaxially stretched molded container 1) In order to improve barrier properties, especially oxygen barrier properties, oxygen barrier resin is combined with the above-mentioned oriented polyolefin or thermoplastic polyester to form a multilayer biaxially stretched molded container. This is already known, for example, in JP-A-57-75826, a preformed material of an oriented thermoplastic resin such as polypropylene or polyester is coated with a solution or emulsion of adhesive and gas barrier resin. However, it is disclosed that an oriented thermoplastic resin is further provided on this coated surface by injection or extrusion to form a multilayer parison, and this multilayer parison is subjected to biaxial stretching blow molding.

However, in this molding method, when the injection molded preform is extracted from the injection mold (core) and subjected to solution coating, it is extremely difficult or impossible to reinsert the coated preform into the injection mold. If the preform is coated and dried without being removed from the injection mold, very expensive equipment is required.

The object of the present invention is to eliminate the above-mentioned drawbacks and improve gas barrier properties. It is an object of the present invention to provide a method for manufacturing a multilayer biaxially stretched molded container having a high gas barrier property, which provides a significant improvement and shows no tendency for the peel strength to decrease substantially even when subjected to repeated drop impacts. That is, the object of the present invention is to prepare a multilayer preform comprising inner and outer polypropylene surface layers and, if necessary, a gas barrier resin intermediate layer provided via an adhesive layer, in the axial direction under conditions that cause molecular orientation of the polypropylene. In the method for producing a multilayer stretched polypropylene bottle, which involves stretching in the circumferential direction and stretching in the circumferential direction by blowing, a coating liquid of a gas barrier resin is applied to one surface of a preformed primary polypropylene preform. The coating preform is heated to a temperature that has elastic deformability but does not cause whitening, and the temperature-controlled coating preform is mounted in an injection mold, and the outer surface is coated on the coating layer. An object of the present invention is to provide a method characterized in that a multilayer preform is formed by injection molding polypropylene to form a layer.

According to the present invention, in a multilayer biaxially stretched molded container comprising a stretched hollow molded multilayer preform having crystalline polypropylene in the inner and outer layers, each of the inner surface layer and the outer surface layer of the container wall is heated. Comprising a moldable, oriented thermoplastic polymer, an intermediate thin layer of adhesive and gas barrier resin applied as a solution or emulsion is interposed between the inner and outer surface layers. Multilayer 2 characterized by
An axially-stretched molded container is provided.

According to the present invention, a solution or emulsion of a gas barrier resin, and if necessary a solution or emulsion of an adhesive resin, is applied to one surface of the primary preform made of crystalline polypropylene to form a secondary preform. A step of forming a secondary preform (a preform) and a temperature at which the secondary preform is elastically deformable, preferably from 120C to 1
A step of adjusting the temperature to 70 U and inserting it into an injection mold, a step of injecting crystalline polypropylene onto the coated surface of the secondary preform to form a tertiary preform (multilayer preform), and a step of forming the multilayer preform. Inner surface side and outer surface fl
A multilayer biaxially stretched molded container comprising the steps of stretching in the axial direction and stretching in the circumferential direction by blowing under temperature conditions that cause molecular orientation of the crystalline polypropylene in at least the -• direction of ll+. The manufacturing method is the same.

In FIG. 1 showing a multilayer biaxially stretched molded container 1 according to the present invention, this container has a mouth 2 equipped with 83 Mtt (e.g. screws, pins, etc.) for fastening a lid (not shown).
, a body wall part 6 continuous to the mouth part, and a bottom wall part 4 continuous to the body wall part.

As is clear from the cross-sectional portion of FIG. gas barrier resin layer 7 applied as a solution or emulsion having
An adhesive resin layer 8.9 is provided between the gas barrier resin layer 7 and the gas barrier resin layer 7.

Generally, resins with excellent gas barrier properties are polymers containing a high concentration of polar groups such as hydroxyl groups, halogen atoms, or nitrile groups, and these resins have strong hydrogen bonds and are difficult to melt. Even if it is possible to melt the resin, the melting temperature and the thermal decomposition temperature are close to each other, so there are many restrictions when molding it, and especially coextrusion with other oriented resins is difficult. accompanied by.

The present invention uses gas barrier resins that are soluble in solvents in the form of a solution, and even those that are insoluble in solvents in the form of an emulsion, that is, a latex. Incorporated as an intermediate layer into a multilayer preform regardless of the thermoforming temperature of the gas barrier
This has succeeded in further improving sexual performance.

It should be noted here that an important problem that arises when applying a gas barrier resin as a solution or emulsion is that the resin layer formed may have poor gas barrier properties due to mechanical or physical reasons. This means that it is easy to obtain. For example, gas barrier resin layers applied in the form of emulsion particles tend to have gaps between the particles.
This gap becomes a gas passage and the original gas barrier properties are lost. However, when coding with such a liquid, pin poles etc. generally occur (1
Hey, l! -1. It causes a decrease in gas barrier weight.

On the other hand, according to the present invention, a single layer preform of polypropylene coated with a gas barrier resin as a solution or emulsion is then coated with a polypropylene by injection molding. By adding it to the molding process, the heat generated during stretch molding and the spreading action create a gas barrier that is sandwiched between these.
The resin layer is uniformly formed, and the gas barrier properties cannot be significantly improved. Of course, according to the present invention,
The intermediate layer 7 of the gas barrier resin layer is mechanically protected by the inner and outer surface layers of polypropylene sandwiching the resin layer (11), and the adverse effects of humidity and container contents on the gas barrier properties of the inner and outer surface layers 11). The effect of being blocked by 15 points is also added.

In the multilayer biaxially stretched molded container according to the present invention 6, the oxygen barrier resin layer 7 is firmly bonded to the inner and outer surface layers 5 and 6 via adhesive resin layers 8 and 9 as necessary. It has the additional advantage that its adhesive strength (peel strength) is significantly less prone to decrease with repeated impact.

In the present invention, at least one, preferably both, of the inner surface layer 5 and the outer surface layer 6 of the oriented resin are subjected to stretch blow molding to achieve remarkable molecular orientation in both the in-plane direction, that is, the axial direction and the circumferential direction of the container. Although the intermediate layer 7 is generally oriented, it may be unoriented in some cases. The thickness of the intermediate layer 7 is considerably thin, as it is applied in the form of a solution or emulsion and is subsequently stretch-formed, and is generally in the range from 6 to 60 microns, in particular from 5 to 15 microns; The thickness of the adhesive resin layers 8, 9 is in the range 05 to 15 microns, in particular 1 to 10 microns.

On the other hand, the thickness of the inner and outer surface layers 6 and 7 varies depending on the type of resin and the purpose, but each has a thickness of 800 to 40 microns,
! It is preferable that the thickness be in the range of 4 [10 to 60 microns].

In the present invention, gas barrier resin and 1. The following will be used:

(1) Partially acetalized polyvinyl alcohol to hydroxyl group-containing polymer polyvinyl alcohol, partially saponified polyvinyl acetate, partially acetalized polyvinyl acetate, partially crosslinked saponified ethylene-vinyl acetate copolymer Polyvinyl alcohol, unsaturated carboxylic acid grafted polyvinyl alcohol:
Water-soluble polysaccharide polymers such as unsaturated carboxylic acid grafted starch, unsaturated carboxylic acid grafted dextrin, ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, and cyanoethylated starch; hydroxyethyl acrylate-1/acrynodic acid ethino copolymer Hydroxyl group-containing acrylic resin, etc.

(2), halogen-containing polymers polyvinylidene chloride, polyvinyl chloride, vinyl chloride/vinylidene chloride copolymers, etc.
nor/butadiene copolymer, acrylonitrile/methyl methacrylate copolymer, acrylonitrile/methyl methacrylate copolymer, etc.

It should be understood that the polymers exemplified 1 through V) above are for illustrative purposes only and that many other polymers may be used. Suitable gas barrier resins for use in the present invention include polymer 10(lA
If the polymer is contained in a concentration of 11 to 60 CJmeq (milli-equivalent), the adhesion between the inner and outer surface layers and the intermediate layer is good, and the adhesive resin layer can be omitted. These resins can be used alone or in combination of two or more.

As the adhesive resin, the following can be mainly used.

(1) Urethane adhesive Diincyanate compounds such as tolylene diisocyanate, methylene diphenyl diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, ethylene glycol,
Polyoxypropylene 1) Ethyl acetate, toluene, methyl ethyl 7% pure or mixed solution of polyether such as coal or polyester such as a condensation of adipic acid and ethylene glycol f2) Vinegar iW vinyl aqueous Emulsion (3) Ethylene-vinyl acetate hot melt adhesive (4) Urethane hot melt adhesive Crystalline polypropylene includes propylene homopolymer, propylene and ethylene, butene-1, styrene, acrylic acid,
Copolymers with monomers such as methacrylic acid, maleic acid, maleic anhydride, and fumaric acid are preferably used.

In addition, the performance of each resin may be adjusted as necessary for the barrier resin, adhesive resin, and crystalline polypropylene mentioned above.
6. Colorants, ultraviolet absorbers, antistatic agents, etc. within the range that does not cause
It is also possible to incorporate scale additives.

A mechanical scale for forming a container according to the present invention will be explained with reference to FIGS. 2 to 7.

In FIG. 2, polypropylene is injected from an inner layer injection machine (not shown) into an inner layer mold 10.10 to form a bottomed single-layer preform 11.

i) Place the neck of the form 11 into the neck holder 12
．． 12 or by other means to hold the coating bottle for the next process)
134 and immersed in the coating pot, the adhesive resin solution or latex is applied to the outer surface of the primary preform, and after drying and removing the solvent in the coating solution or the water in the latex, it is transferred to the gas barrier in the next step. Transfer to a adhesive resin coating pot, apply a gas barrier resin solution or latex to the coating surface of the adhesive-coated preform 1, dry it, and further apply an adhesive resin solution or latex to this preform, After drying, the coating preform 1 shown in FIG.
form 5.

This coated preform 15 is heated or cooled to a temperature at which the preform has elastic deformability, preferably in the range of 120C to 170C. Adjust the temperature. The temperature-controlled coating preform is inserted into a male injection mold (core) 16 shown in FIG. Here, it is important to adjust the temperature of the coating ZOLIFO=1.15 to the above-mentioned temperature range, so that it can be inserted into the injection molding male mold 16 and brought into close contact. 17 This coating preform 15 is cooled and solidified without temperature control.1. If the preform is
Since the preform cannot be inserted into the male mold or does not come into close contact with the male mold, the next injection cannot be performed accurately.

Paint preform 15 inserted into injection molding male mold 16
A multilayer preform 18 as shown in FIG. 6 is formed by injecting polypropylene from an outer layer injection machine (not shown).

This multilayer preform 18 is heated to a temperature suitable for stretch blow molding, for example, 120C to 170C, and the neck portion of this multilayer preform 18 is held by a neck holder 19 using a blow molding apparatus shown in FIG. The biaxially stretched multilayer bottle 1 is set in a blow mold 20 and stretched vertically with a stretching rod 21, while being blow molded.
form.

By the way, when the multilayer preform 18 is taken out from the mold, the temperature of the injection molds (male and female) shown in FIG. 5 is adjusted so that the multilayer preform 18 is at an appropriate temperature for stretching. It is also possible to leave it there.

Coating with oxygen barrier resin and adhesive resin can be done by dipping, spray painting, electrostatic painting, roll coating,
...Can be applied by coating etc. The concentration of the resin liquid generally ranges from 20 to 60% by weight in terms of resin solid content, and the viscosity can range from 100 to 1,000 centivoise. As the solvent, water or an organic solvent or a combination thereof is used.

After drying the coated resin layer, the obtained coated molded product is subjected to second to fourth stage injection molding to obtain a multilayer preform.

Axial stretching and circumferential expansion of the multilayer preform it, t
It is carried out at a temperature at which molecular orientation of the fat effectively occurs. These stretch forming temperatures and stretching ratios are also well known per se, and the present invention is also carried out under well known conditions.

In the present invention, if the molecular orientation of the resin sections of the inner and outer surface layers is controlled so that the in-plane orientation coefficient (L+rn) is 03 or more, especially 04 or more, transparency, rigidity, and impact resistance can be improved to 1. You can get the same results as you want.

The invention is illustrated by the following example.

Example 1 A preform of polyglobylene homopolymer having a length of 110 mm, an inner diameter of 25 φ, and a wall thickness of 2.0 mm was injection molded, and this preform was coated with a urethane adhesive solution (Tolune diisocyanate and linear polyester). methyl ethyl ketone solution), dried with hot air at a temperature of 145C, and then
This painted preform is immersed in a mixed solution of ethylene-vinyl alcohol copolymer/proper tool/water at 1.120?
The process of drying with hot air at a temperature of 145°C was repeated 6 times, and then immersed in the urethane adhesive solution, followed by drying with hot air at a temperature of 145°C. The polyglobylene homopolymer was injected onto the inner surface (outer surface) of the painted preform to form a multilayer film with a wall thickness of 3.5 mm. 1. Form a brihumeno and heat this multilayer brihumeno to a temperature of 165C. After that, stretch blow molding is performed to obtain a body with an average wall thickness of 30 mm (J tt , internal volume of 50 mm).
A multilayer bottle of 0 c, c was obtained.

This bottle has an oxygen permeability of 2.3 cQlday, -
Atm-31', it was less than 1/100 of that of a single polypropylene homopolymer bottle, and no peeling between the layers was observed after repeated drops 10 times.

Example 2 A preform of ethylene-propylene copolymer (intrinsic viscosity 0.7) with a length of 110 mm, an inner diameter of 25 φ, and a wall thickness of 2.0 mm was injection molded, and this preform was coated with a urethane adhesive solution (hexamethylene 12.16 Soaking diisocyanate and linear polyester in methyl ethyl ketone solution)
After drying with hot air at a temperature of 5C, the painted preform was immersed in vinylidene chloride-based aqueous latex and heated at 120C.
The process of drying with hot air at a temperature of Insert into the injection mold (core) at a temperature of
The above-mentioned polyethylene prephthalate was injected onto the painted surface (outer surface) of the painted preform to form a multilayer preform with a wall thickness of 5 III m.1- This multilayer preform was heated to a temperature of 155C and then stretched. A multilayer bottle with an average body wall thickness of OOμ and a content fa of 500 cc was obtained by blow molding I7.

This bottle has an oxygen permeability of 4.7 CC,/da, y
・At αtra・37tr, the temperature was 1150 F or more compared to the single ethylene-propylene co-M combination bottle, and no peeling between the layers was observed after 10 repeated drops.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a multilayer biaxially stretched molded container molded according to the present invention; FIG. 2 is a sectional view of a single-layer preform injection molding apparatus and a side sectional view of a single-layer preform molded by this apparatus; Fig. 6 is a sectional view of the coating pot, Fig. 4 is a side sectional view of the coating preform, Fig. 5 is a sectional view of the injection molding apparatus for multilayer resin, and Fig. 6 is a side sectional view of the multilayer preform. FIG. 7 is a sectional view of the stretch blow molding apparatus. 1...Multilayer biaxially stretched molded container, 5...
Inner surface layer, 6... Outer surface layer, 7... Intermediate layer, 8, 9... Adhesive resin layer, 11...
...-Next preform, 15...Painted preform, 18...Multilayer preform. Patent applicant: Toyo Seikan Co., Ltd. Figure 1 Figure 2 Figure 0 Figure 3 - Figure 4 Figure 5 Figure 6 Figure 7

Claims (5)

[Claims] (1) A multilayer preform comprising inner and outer polypropylene surface layers and, if necessary, a gas barrier resin intermediate layer provided via an adhesive layer L7, is stretched in the axial direction under conditions that cause molecular orientation of the polypropylene. In the manufacturing method of a multilayer stretched polypropylene bottle, which involves stretching in the circumferential direction by blowing, a coating liquid of gas barrier resin is applied to one surface of a primary polypropylene preform formed in advance;
After drying, the coated preform is heated to a temperature that allows elastic deformation but does not cause whitening, and the temperature-controlled coated preform is mounted in an injection mold, and the inner or outer surface is coated on the coated layer. A method characterized by injection molding polypropylene to form a multilayer preform. (2) The method according to claim 1, wherein a gas resin is applied to the outer surface of the primary preform, and polypropylene to be the outer surface layer is injected onto the coated layer. (3) An adhesive is applied to the primary preform before the gas barrier resin is applied, and the adhesive is applied on the gas barrier resin layer after the gas barrier resin is applied. Method described. (4) The method according to claim 1, wherein the temperature of the preform after painting is adjusted to a temperature of 1000 to 170C. (5) The method according to claim 1, wherein the temperature-controlled preform is mounted on the core of an injection mold.