JP4265122B2 - Multilayer bottle - Google Patents

Description

【００９８】
次いで、前記実施例及び比較例で得られた多層ボトルを高さ方向に切断し、顕微鏡によりボトル底部からサポートリング下部まで各層の膜厚を測定した。
また、前記成形性の評価で問題がなかった実施例１乃至３及び比較例４、５のボトルについて、耐香気性、ガスバリヤー性及び耐衝撃性に関する評価を行った。
【００９９】
2.耐香気性
内層樹脂層の膜厚が異なる、前記実施例１および比較例５により得られた各多層ボトルについて、日本茶を５００ｃｃ充填、ヘッドスペースを窒素置換した後、温度５０℃、相対湿度８０％の環境化で１ヶ月保存し、味、色、臭いなどについて内容物の変化を調べた。
その結果、比較例５は、臭い、味とも変化し、若干褐変していた。
【０１００】
3.ガスバリヤー性
全重量当たりガスバリヤー性樹脂の割合が５％である前記実施例１および比較例４，５により得られた各多層ボトルについて、温度３０℃、相対湿度８０％の環境化における酸素透過量（１気圧における単位面積（１ｍ²）当たりの１日の透過酸素量cc）を測定した。
その結果比較例４は内層樹脂層の膜厚が薄いため、実施例１と比べ約５０％程度性能が低下した。また、比較例５はゲート部近傍のガスバリヤー性樹脂層の乱れに起因して、実施例１に比べ若干の性能低下が確認された。
【０１０１】
４．耐衝撃性試験
５００ｃｃの水を入れて密封した多層二軸延伸ボトルを、高さ１２０ｃｍからコンクリート床上に各１０本づつ垂直落下させて、破損したボトル本数を調べた。
その結果、比較例５は底部ゲート付近で一部デラミした。
以上、香気性、ガスバリヤー性及び耐衝撃性の評価結果を表２に示す。
【０１０２】
【表２】

【０１０３】
【発明の効果】
本発明によれば、内外層樹脂中に全体当たり１乃至１５重量％のガスバリヤー性樹脂を中間層として内封させ、しかも底部においてガスバリヤー性樹脂を連続させ、ガスバリヤー性樹脂中間層を器壁の厚み方向中心よりも径内方向に偏って存在させ、また内層樹脂を少なくとも２５μｍの厚みに保持させ、更に底部にゲート部を有しないようにすることにより、底部における多層構造の整合性に優れ、その結果ガスバリヤー性、耐圧強度、耐衝撃性、耐熱性等に優れている多層ボトルを得ることができる。
【図面の簡単な説明】
【図１】本発明多層ボトルの製造に用いる圧縮成形装置全体の配置の一例を示す側面図である。
【図２】バリヤー性樹脂を内封した溶融樹脂塊の押出装置の詳細を示す断面図である。
【図３】接着剤樹脂およびバリヤー性樹脂を内封した溶融樹脂塊の押出装置の詳細を示す断面図である。
【図４】一段圧縮成形法に用いる装置の全体配置の他の例を示す側面図である。
【図５】本発明のボトルの製造に用いる多層プリフォームの参考断面図である。
【図６】本発明による多層二軸延伸ブロー成形ボトルの参考断面図である。
【図７】本発明のボトルの製造に用いる他の多層プリフォームの参考断面図である。
【図８】本発明による他の多層二軸延伸ブロー成形ボトルの参考断面図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-layer bottle, and more particularly to a multi-layer bottle excellent in the consistency of the multi-layer structure at the bottom, and as a result, excellent in gas barrier properties, pressure strength, impact resistance, and heat resistance.
[0002]
[Prior art]
Stretch blow-molded plastic bottles, especially polyester bottles, are now common, and because of their excellent transparency and moderate gas barrier properties, beer can be used in addition to liquid products such as liquid detergents, shampoos, cosmetics, soy sauce, and sauces. It is widely used in carbonated beverages such as cola and cider, and other beverage containers such as fruit juice and mineral water.
[0003]
The production methods of stretch blow bottles are roughly classified into a hot parison method and a cold parison method. In the former hot parison method, a preform formed by injection molding of polyester is stretch blow molded in a hot state without being completely cooled. On the other hand, in the latter cold parison method, a supercooled bottomed preform, which is considerably smaller than the final container and the polyester is amorphous, is formed in advance by injection molding of polyester, and this preform is preliminarily maintained at its stretching temperature. A method of heating and drawing in the axial direction in the blow mold and blow drawing in the circumferential direction is adopted.
[0004]
Multi-layer gas barrier stretched polyester bottles have also been known for a long time. For example, Japanese Patent Publication No. 3-67983 discloses an inner layer and an outer layer made of a polyester resin, an intermediate layer made of an ethylene vinyl alcohol copolymer, and the above-mentioned interlayer. A multilayer gas barrier stretched polyester bottle with a nylon 6 / nylon 6,6 copolymer adhesive layer is described.
[0005]
In order to manufacture a stretched multilayer bottle, it is first necessary to manufacture a preform having a multilayer structure. In order to manufacture this multilayer preform, various methods such as a co-extrusion molding method, a multi-stage injection molding method, and a co-injection molding method are used. This method is used.
[0006]
[Problems to be solved by the invention]
However, when any of these methods is used, it is almost impossible to make each resin layer continuous at the bottom of the multilayer preform, and in particular to completely enclose the gas barrier resin intermediate layer between the inner and outer layers.
For example, in the coextrusion method, it is necessary to close the end portion of a multilayer pipe-shaped molded body by fusion bonding to form a bottom portion, and the disorder of the layer occurs at the time of this closing. In the case of the injection molding method, each resin layer is also disturbed by the inflow of resin from the gate portion at the center of the bottom.
[0007]
In particular, in the center of the bottom of the preform, there is a problem that the gas barrier resin layer is exposed on the outer surface or the inner surface. When such an exposed portion of the gas barrier resin is present, moisture absorption or water absorption of the gas barrier resin The performance of the gas barrier resin is greatly reduced. Also, if gas barrier resin is mixed in the outer layer resin part or the inner layer resin part, it becomes difficult to stretch and align this part, so it is difficult to increase the pressure resistance of the bottom part. Will occur. Furthermore, since sufficient orientation crystallization cannot be performed by heat setting, the heat resistance is also lowered.
[0008]
  Therefore, the object of the present invention is excellent in the consistency of the multilayer structure at the bottom, and as a result, is excellent in gas barrier properties, pressure strength, impact resistance, heat resistance, etc.Multilayer bottle and method for producing the sameTo provide.
  In the present specification, the consistency of the multilayer structure at the bottom means a state in which a large number of layers are continuously stacked in parallel at the bottom.
[0009]
[Means for Solving the Problems]
  According to the present invention, a multi-layer bottle formed by biaxially stretching blow-molding a test tube-shaped multi-layer preform obtained by compression molding, the total amount of 1 to 15% by weight in the inner and outer layer resin The gas barrier resin is enclosed as an intermediate layer, and the intermediate layer of the gas barrier resin is continuous at the bottom, but the intermediate layer is not present at the mouth, and the intermediate layer is There is provided a multilayer bottle characterized in that the inner wall resin is deviated in the radial inner direction from the center in the thickness direction of the vessel wall, and the inner layer resin has a thickness of at least 25 μm.
  In the multilayer bottle of the present invention,
1. The inner / outer layer resin is a polyester resin or an olefin resin, and the gas barrier resin is at least one selected from the group consisting of an ethylene vinyl alcohol copolymer, a polyamide resin, and a cyclic olefin copolymer;
2. Between the inner and outer layers and the gas barrier resin intermediate layer, 1 to 15% by weight of the adhesive resin layer is provided as a whole.thing,
Is preferred.
  Further, the above multi-layer bottle supplies a molten resin lump encapsulated in a state where the gas barrier resin is decentered downward in the inner and outer layer resins to a cavity mold, and compresses it with a core mold to form a test tube-shaped multi-layer bottle. It is manufactured by forming a preform and biaxially stretching blow-molding the multilayer preform.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[Action]
The multilayer bottle of the present invention comprises an inner layer, an outer layer and a gas barrier resin intermediate layer.
(1) 1 to 15% by weight of gas barrier resin per whole was encapsulated in the inner and outer layer resin as an intermediate layer;
(2) The gas barrier resin is made continuous at the bottom,
(3) The gas barrier resin intermediate layer is present in a radially inward direction with respect to the thickness direction center of the vessel wall,
(4) The inner layer resin has a thickness of at least 25 μm,
(5) having no gate at the bottom,
Is a feature.
[0011]
The fact that the gas barrier resin is encapsulated in the inner / outer layer resin as an intermediate layer means that no gas barrier resin is present on the inner and outer surfaces of the bottle and only the inner / outer layer resin is present. A bottle in which the gas barrier resin of the intermediate layer is encapsulated can be manufactured by using a preform in which the gas barrier resin of the intermediate layer is encapsulated, which will be described in detail later.
[0012]
In the present invention, the gas barrier resin is contained in an amount of 1 to 15% by weight based on the whole. Gas permeation through the bottle wall is inversely proportional to the thickness of the gas barrier resin. If the amount of the gas barrier resin is less than 1% by weight, it is not preferable because the thickness of the bottle wall must be increased and the container weight increases. On the other hand, when the amount of the gas barrier resin exceeds the above range, it is not preferable from the viewpoints of deterioration of moldability from the preform to the bottle and economical efficiency.
[0013]
In the bottle of the present invention, it is also an important feature that the gas barrier resin is continuous at the bottom. “Continuous” means that there is no step or interruption, and the gas barrier resin in the intermediate layer is completely continuous. In bottles and preforms for forming bottles, the radial dimensions of the mouth and trunk may be considered to be approximately constant, whereas the radial dimension of the bottom is large and abrupt. Therefore, it is almost impossible to make the intermediate layer continuous. However, according to the present invention, the intermediate layer at the bottom can be made continuous by using the molding method described later.
[0014]
In the present invention, the gas barrier resin intermediate layer is present in a radially inward direction with respect to the thickness direction center of the vessel wall. Thereby, the flavor fall by adsorption | suction of an aromatic component can be prevented. In general, the adsorption of gas by the resin component is considered to occur at a considerable rate in the amorphous portion, while being almost zero in the crystalline portion.
In the present invention, by providing the gas barrier resin intermediate layer so as to be biased toward the radially inner side, adsorption of aroma components and the like by the inner layer resin can be suppressed to a low level, and flavor retention with respect to the contents can be improved. . Moreover, the oxidative degradation of the contents can be reduced by suppressing the migration of dissolved oxygen in the inner layer resin to the contents.
[0015]
In the present invention, as described above, the gas barrier resin intermediate layer is present in a radially inward direction with respect to the thickness direction center of the vessel wall. However, it is still characterized in that the inner layer resin has a thickness of at least 25 μm. is there.
The gas barrier property of the gas barrier resin is due to the strength of hydrogen bonds in the resin. On the other hand, this hydrogen bond is weakened by the coexistence of moisture. Therefore, the gas barrier resin is easily affected by moisture contained in the contents, and the gas barrier property is likely to be lowered.
In the present invention, by ensuring the above thickness for the inner layer resin, it is possible to avoid the influence of moisture on the gas barrier resin.
[0016]
  The bottle of the present inventionBecause it is formed by biaxial stretch blow molding using a test tube-shaped multilayer preform obtained by compression molding,It is a remarkable feature that there is no gate part at the bottom. In this specification, a gate part means the part which is the entrance of the resin inevitably generated with injection molding, and the remainder. In the present invention,By using a preform molded by compression molding,The formation of a gate portion that causes disturbance in the resin flow of the intermediate layer, the inner and outer layers, and the adhesive layer was avoided. As a result, it is possible to produce a multi-layer bottle that is excellent in the consistency of the multi-layer structure at the bottom, and as a result is excellent in gas barrier properties, pressure strength, impact resistance, heat resistance, and the like.
[0017]
In the multilayer bottle of the present invention, the inner / outer layer resin is a polyester resin or an olefin resin, and the gas barrier resin is selected from the group consisting of an ethylene vinyl alcohol copolymer, a polyamide resin, and a cyclic olefin copolymer. It is preferable that there is at least one.
By using the above as the inner and outer layer resin, it is possible to impart molecular orientation by biaxial stretching, thereby improving the pressure strength, impact resistance, heat resistance, transparency, etc. Convenient.
On the other hand, ethylene-vinyl alcohol copolymer and polyamide resin are excellent in gas barrier property against oxygen, while cyclic olefin copolymer is excellent in gas barrier property against water vapor. Thereby, the preservability of the contents of the bottle can be improved.
[0018]
  In the bottle of the present invention, the mouth portion is formed only of the inner and outer layer resin.BecauseSealability and hygieneExcellent characteristics.In addition, by forming the mouth portion only with the inner and outer layer resins, the inner sealing state of the intermediate layer resin can be made complete, and the deterioration of gas barrier properties due to moisture absorption can be prevented.
[0019]
  Of the present inventionThe bottle is made of gas barrier resinA molten resin lump encapsulated in an inner and outer layer resin in a state of being eccentric downward is supplied to a cavity mold and compressed by a core mold to form a multilayer preform, and this multilayer preform is biaxially stretch blow molded ByIt is formed.When this molten resin mass is compressed with the core mold, the gas barrier resin is contained in the molten resin mass in a state of being eccentric downward, so that the inner and outer layers are formed on the upper part of the molten resin mass with which the core mold first engages. Only the resin exists, and the inner and outer layer resins flow upward and downward along the cavity mold by the pressing by the core mold. Finally, the portion containing the gas barrier resin is pressed with a core mold, and a preform capable of forming a bottle that satisfies the requirements (1) to (5) described above is obtained. It should be emphasized that the preform formed by the above compression molding method does not have a gate portion that causes disturbance of the resin flow in the intermediate layer and the inner and outer layers.
[0020]
In the present invention, an adhesive resin layer can be provided between the inner and outer layers and the gas barrier resin intermediate layer. By providing the adhesive resin layer, the interlayer adhesion between the inner and outer layers and the intermediate layer can be improved, and delamination due to a drop impact or the like can be prevented.
When an adhesive resin layer is provided between the inner and outer layers and the gas barrier resin intermediate layer, it is preferable to provide an adhesive resin layer of 1 to 15% by weight based on the whole, and the amount of the adhesive resin is 1 If the amount is less than%, the adhesive strength between the inner and outer layers and the gas barrier resin intermediate layer is insufficient. On the other hand, if the amount of the adhesive resin exceeds the above range, the moldability from the preform to the bottle is reduced and the economic efficiency is reduced. It is not preferable in terms of the aspect.
In addition, when this adhesive resin layer is provided, it is important to continue the adhesive resin layer at the bottom, thereby increasing the mechanical strength of the bottom and preventing delamination and breakage at the time of dropping. It becomes possible.
[0021]
A biaxial stretch blow molded multilayer bottle is obtained by biaxially stretch blow molding the multilayer preform by means known per se. The mouth and neck of this bottle are the same as that of the preform, and are formed only from the inner and outer layer resins, and are excellent in sealing performance and hygienic characteristics.
In addition, the gas barrier resin intermediate layer or the gas barrier resin intermediate layer and the adhesive resin layer are completely enclosed in the inner and outer resin layers at the body and bottom of the bottle. The heat resistance and heat resistance are also maintained at the same level as that of the resin not containing the intermediate layer resin. Furthermore, this multilayer bottle has a feature that it is transparent without whitening at the bottom in a state where no pigment is blended.
[0022]
[resin]
(1) Inner and outer layer resin:
In the present invention, as the molding resin, any plastic material that can be stretch blow molded and thermally crystallized can be used, and examples thereof include polyester resins and olefin resins that can be stretch-oriented.
Among these resins, polyester resins, particularly ethylene terephthalate polyester resins are advantageously used. Of course, other polyesters such as polybutylene terephthalate and polyethylene naphthalate, or blends with polycarbonate or arylate resins are used. You can also.
[0023]
The ethylene terephthalate-based polyester resin used in the present invention occupies most of the ester repeating units (generally 70 mol% or more, particularly 80 mol% or more), and the ethylene terephthalate unit has a glass transition point (Tg) of 50 to 50%. A polyester resin having a melting point (Tm) of 200 to 275 ° C., particularly 220 to 270 ° C. at 90 ° C., particularly 55 to 80 ° C. is preferred.
[0024]
Homopolyethylene terephthalate is preferred in terms of heat and pressure resistance, but a copolyester containing a small amount of ester units other than ethylene terephthalate units can also be used.
Dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. 1 type or combination of 2 or more types of diol components other than ethylene glycol include propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexane di 1 type, or 2 or more types, such as methanol and the ethylene oxide adduct of bisphenol A, are mentioned.
[0025]
In addition, a composite material obtained by blending ethylene terephthalate-based polyester resin with a relatively high glass transition point such as polyethylene naphthalate, polycarbonate, or polyarylate in an amount of about 5% to 25% can be used. Strength can be increased.
Further, polyethylene terephthalate and the above-mentioned material having a relatively high glass transition point can be laminated and used.
[0026]
The ethylene terephthalate-based polyester resin to be used should have at least a molecular weight sufficient to form a film, and an injection grade or an extrusion grade is used depending on the application. The intrinsic viscosity (IV) is generally in the range of 0.6 to 1.4 dL / g, particularly 0.63 to 1.3 dL / g.
[0027]
On the other hand, as the olefin-based resin, all olefin-based resins used for the production of this type of biaxial stretch blow molded bottle can be used, but propylene-based polymers are particularly preferable.
As the propylene-based polymer, any propylene homopolymer or copolymer can be used as long as it is mainly composed of propylene and is crystalline. A structure may be used.
[0028]
The propylene copolymer is mainly composed of propylene and has other olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl 1-pentene, 1-decene and the like. Copolymers containing 4 to 20 α-olefins are used. The propylene unit content in the copolymer is suitably 50 to 100% by weight, particularly 70 to 90% by weight. These propylene copolymers may be random copolymers or block copolymers.
[0029]
The crystalline propylene polymer used in the present invention generally has a melting point of 100 to 180 ° C. (peak melting point by differential thermal analysis) from the viewpoint of heat resistance, mechanical properties and workability, while moldability and In terms of mechanical properties, the melt flow rate (JIS K6758) is preferably in the range of 0.8 to 12 g / 10 min.
[0030]
The specific type of the propylene polymer to be used can be variously selected or further combined depending on the required properties. For example, homopolypropylene is used when high mechanical properties and heat resistance are required, and random propylene copolymer is often used when high transparency is required. On the other hand, when moldability is required, it is recommended to use a block propylene copolymer. Of course, these propylene polymers are not limited to use alone, but it is also understood that two or more propylene polymers can be used in the form of a blend or in the form of a laminate. Should.
[0031]
The inner and outer layer resins used in the present invention may contain known plastic compounding agents such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, fillers, colorants and the like. For the purpose of making the molded container opaque, fillers such as calcium carbonate, calcium silicate, alumina, silica, various clays, gypsum, talc, magnesia, titanium white, yellow iron oxide, bengara, ultramarine blue, chromium oxide, etc. Inorganic pigments and organic pigments can be blended.
[0032]
(2) Gas barrier resin:
As the gas barrier resin, any known one, for example, ethylene-vinyl alcohol copolymer (EVOH), nylon resin (Ny), gas barrier polyester resin (BPR), cyclic olefin copolymer (COC), etc. Can be used.
[0033]
As the gas barrier resin layer, an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 40 to 85 mol%, particularly 50 to 80 mol% is suitable.
The molecular weight of the ethylene-vinyl alcohol copolymer is not particularly limited as long as it is a molecular weight sufficient to form a film, but is generally 30 ° C. in a mixed solvent of 85% by weight of phenol and 15% by weight of water. The intrinsic viscosity is preferably in the range of 0.01 to 0.05 dL / g.
[0034]
Other examples of the gas barrier resin include nylon resins such as nylon 6, nylon 6,6, nylon 6 / nylon 6,6 copolymer, and xylylene group-containing polyamide.
Examples of the ω-aminocarboxylic acid component constituting the nylon resin include ε-caprolactam, aminoheptanoic acid, aminooctanoic acid and the like, and examples of the diamine component include aliphatic diamines such as hexamethylenediamine and fats such as piperazine. Cyclic diamines, m-xylylenediamine and / or p-xylylenediamine, and the like. Examples of the dibasic acid component include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, suberic acid, aromatic dicarboxylic acids, Examples thereof include terephthalic acid and isophthalic acid.
As particularly excellent barrier properties, 35 mol% or more, particularly 50 mol% or more of the diamine component is m-xylylene and / or p-xylylenediamine, and the dibasic acid component is an aliphatic dicarboxylic acid and / or aromatic. Mention may be made of polyamides which are group dicarboxylic acids and optionally contain not more than 25 mol%, in particular not more than 20 mol%, of ω-aminocarboxylic acid units per total amide repeating unit.
The polyamide used preferably uses 96% by weight sulfuric acid and has a relative viscosity (ηrel) of 0.4 to 4.5 measured at a concentration of 1 g / 100 ml and a temperature of 25 ° C.
[0035]
A gas barrier polyester can also be used as the gas barrier resin. One kind of the gas barrier polyester (hereinafter sometimes referred to as BPR) includes a terephthalic acid component (T) and an isophthalic acid component (I) in a polymer chain.
T: I = 95: 5 to 5:95
Especially 75:25 to 25:75
The ethylene glycol component (E) and the bis (2-hydroxyethoxy) benzene component (BHEB)
E: BHEB = 99.999: 0.001 to 2.0: 98.0
Especially 99.95: 0.05 to 40:60
In a molar ratio. As BHEB, 1,3-bis (2-hydroxyethoxy) benzene is preferable.
The polyester (BPR) should have a molecular weight sufficient to form at least a film, and is generally measured in a mixed solvent of phenol and tetrachloroethane in a 60:40 weight ratio at a temperature of 30 ° C. It is desirable to have an intrinsic viscosity of 0.3 to 2.8 dL / g, especially 0.4 to 1.8 dL / g.
[0036]
In the present invention, a cyclic olefin copolymer can be used as a resin excellent in water vapor permeability. As the cyclic olefin copolymer, an amorphous or low crystalline copolymer (COC) of olefin and cyclic olefin is used.
As the olefin constituting the copolymer, ethylene is preferable, but in addition, there are 3 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl 1-pentene, 1-decene and the like. Twenty to twenty α-olefins are used alone or in combination with ethylene.
As the cyclic olefin, basically, an alicyclic hydrocarbon compound having an ethylenically unsaturated bond and a bicyclo ring, particularly a hydrocarbon compound having a bicyclo [2,2,1] hept-2-ene skeleton, etc. used.
[0037]
This copolymer (COC) is preferably derived from 22 to 50 mol%, in particular 22 to 40 mol% of cyclic olefin and the remaining ethylene. The glass transition point (Tg) is more preferably in the range of 60 to 150 ° C.
The molecular weight of this copolymer is not particularly limited, but it should have an intrinsic viscosity of 0.1 to 20 dL / g measured at 135 ° C. in decalin, and its crystallinity can be determined by X-ray diffraction method. Generally, it is 10% or less, particularly 5% or less.
The copolymer (COC) can be obtained by random polymerization of an olefin and a cyclic olefin in the presence of a vanadium catalyst or a metallocene catalyst known per se.
A suitable copolymer (COC) is available from Mitsui Petrochemical Co., Ltd. under the trade name APEL.
[0038]
(3) Adhesive resin:
When there is no thermal adhesiveness between the inner and outer layer resins and the gas barrier resin layer, an adhesive resin layer can be interposed between the two resin layers.
The adhesive resin is not particularly limited, but a carbonyl group based on carboxylic acid, carboxylic acid anhydride, carboxylate salt, carboxylic acid amide, carboxylic acid ester, etc. in the main chain or side chain is 1 to 700 meq / 100 g resin, particularly Examples thereof include a polymer contained at a concentration of 10 to 500 meq / 100 g resin. Specific examples of adhesive resin include ethylene-acrylic acid polymer, ion-crosslinked olefin polymer, maleic anhydride grafted polypropylene, acrylic acid grafted polyolefin, ethylene-vinyl acetate copolymer, copolymerized polyester, copolymerized polyamide, etc. Or a combination of two or more thereof.
[0039]
[Multilayer preform and its manufacture]
In the present invention, by manufacturing a molten resin lump encapsulated in a state where the gas barrier resin is decentered downward in the inner and outer layer resin, the molten resin lump is supplied to the cavity mold, and compressed by the core mold. Manufacture multilayer preforms.
[0040]
The molten resin lump is used to continuously extrude the inner and outer layer resins into the die using an inner and outer layer resin extruder, a gas barrier intermediate layer resin extruder, an intermediate layer cutting resin extruder and a three-layer triple die. Then, the intermediate layer resin is intermittently extruded into the inner and outer layer resins, and further, the intermediate layer resin is intermittently extruded at a timing so that the intermediate layer resin is enclosed in the inner and outer layer resins in a drop shape. It is obtained by forming a product and cutting this extrudate with a cutter near the die lip at a portion near the lower end of the intermediate layer resin.
The use ratio of the inner / outer layer resin and the gas barrier intermediate layer resin is preferably in the range described above.
When an adhesive resin layer is provided between the inner and outer layers and the gas barrier resin intermediate layer, the inner and outer layer resin extruder, the gas barrier intermediate resin extruder, the intermediate layer and the resin extrusion for cutting the adhesive resin layer In addition to the machine, using an adhesive resin extruder and a four-layer quadruple die, while the inner and outer layer resins are continuously extruded into the die, the intermediate layer resin and the adhesive resin are extruded intermittently while being synchronized with each other, Further, the intermediate layer cutting resin is intermittently extruded at a timing to form an extrudate in which the intermediate layer resin is covered with the adhesive resin layer and encapsulated in the inner and outer layer resins in a drop shape. It is obtained by cutting the product with a cutter near the die lip at a portion near the lower end of the intermediate layer resin.
At this time, it is important that the gas barrier intermediate layer resin is knitted downward in the molten resin mass. When compression molding a molten resin mass in which the gas barrier intermediate layer resin is knitted upward, the film thickness of the inner layer resin becomes extremely thin, which is not preferable in terms of gas barrier properties.
The use ratio of the inner / outer layer resin, the gas barrier intermediate layer resin, and the adhesive resin is preferably in the above-described range.
[0041]
In the present invention, it is preferable to use the above-mentioned molten resin lump and to produce a multilayer preform by compression molding of this molten resin lump, particularly by one-stage compression molding.
That is, at the bottom of the multilayer preform produced by the compression molding method, there is no whitening or the like, and there is substantially no fluid orientation distortion, and a polyester bottle having excellent characteristics can be obtained. In addition to this, many advantages as described below are also obtained.
[0042]
In compression molding, unlike injection molding, processing at a relatively low temperature is possible. In particular, a blow molding preform is obtained by one heating and melting and compression molding, so the degree of thermal degradation of the resin is small, A blow bottle excellent in physical properties can be produced.
[0043]
That is, a cheaper resin can be used to produce a blow molded product having the same physical properties (strength / impact resistance), and a blow bottle with more excellent physical properties can be produced when using the same raw material resin. In addition, resin viscosity is high, and even resin raw materials that are unsuitable for injection molding can be easily molded into bottles through preforms, and it is also possible to obtain large blow bottles that require particularly high impact resistance. .
[0044]
Further, in the one-stage compression molding method, the heat quantity of the molten resin lump of the resin is effectively used at the time of melt extrusion of the resin, and local cooling of this lump is prevented as much as possible. It is preferable not to cool the part forming the bottom of the reform and to prevent the movement of the resin on the mold surface during compression molding in order to produce a preform having a uniform internal structure and excellent stretch blow moldability. .
[0045]
For this purpose, an approximately fixed amount of molten resin mass formed by cutting the extrudate is fed into the female mold (cavity mold) without substantial temperature drop, and the supplied molten resin mass is immediately Compression molding is performed with a male mold (core mold).
Also, during compression molding, the residual air in the mold is quickly discharged, and compression molding is performed on a preform having a bottomed body portion and a mouth portion.
[0046]
In the one-stage compression molding method, the temperature of the resin decreases from the time it is cut into a molten resin lump to the time it is put into a mold, the uniformity of the structure of the bottomed body to be stretch blow molded and the stretch orientation In addition, it has a significant effect on the physical properties of the final blow-molded product, particularly impact resistance. The influence of this temperature decrease is particularly noticeable at the lower part of the molten resin mass forming the bottom of the preform (the bottom of the final blow-molded product).
That is, when the lower part of the molten resin mass is locally cooled, the degree of distortion at the bottom of the preform increases, which causes poor appearance and reduced impact resistance when the final blow molded product is obtained.
In the one-stage compression molding method, after cutting into a molten resin lump, it suppresses the substantial temperature drop of the molten resin lump between the time when the molten resin lump is put into the mold, in particular, the temperature drop within the above time at the lower part of the molten resin lump. By suppressing the above, the above trouble can be effectively solved.
[0047]
As described above, in order to suppress the temperature drop of the molten resin lump, after cutting into the molten resin lump and before putting it into the mold, for example, excluding the gripping part, the molten resin lump and other members Contact should be avoided, and in particular, contact between the lower part of the molten resin mass and other members should be avoided as much as possible.
[0048]
In the preferred manufacturing method, for this purpose, a multilayer molten resin material is extruded parallel to the axial direction of the male mold (core mold) and the female mold (cavity mold), and the cut molten resin mass is parallel to the parallel mold. The material is supplied into the mold while the state is substantially maintained.
[0049]
In addition, it is preferable to supply the molten resin lump in a form of a cylinder or a shape close to a cylinder in order to allow the molten resin lump to be supplied in a substantially quantitative state and to avoid cooling the lower part as much as possible.
Furthermore, for the purpose of avoiding the temperature drop at the lower part of the molten resin mass as much as possible and for the purpose of stably supplying the molten resin mass, that is, for preventing the collapse of the molten resin mass, It is preferable to hold it at the upper part, move from the cutting position to the mold position, and supply it into the mold.
[0050]
In order to avoid cooling of the molten resin mass, it is preferable to start from the cutting to the mold and to start the molding after being put into the mold as quickly as possible. Generally, it takes 1 second from the cutting to the mold. It is recommended that the process be performed within 0.5 seconds from the start of molding to the start of molding.
[0051]
In the one-stage compression molding method, it is also important to perform compression molding while removing residual air at the bottom of the mold or in the vicinity thereof. That is, under the condition where air remains in the mold, wrinkles tend to occur in a portion attached to the mold or in the vicinity thereof. On the other hand, if the air is quickly removed after the molding is started, the generation of wrinkles can be effectively prevented. The cause of wrinkles is thought to be the fact that the close contact part and non-adhesion part on the mold surface are formed at a fine interval, which is believed to be a phenomenon peculiar to compression molding. Then, it seems that the mold surface and the resin are brought into close contact with each other to form a vessel wall without wrinkles.
[0052]
In order to eliminate the residual air on the surface of the female mold, it is only necessary to form an escape path from the molding site to the outside with respect to the residual air, and its means is not particularly limited. A mold having a gap or a porous portion is preferable. It is particularly effective to forcibly remove residual air with an external vacuum pump or the like at the start of molding.
[0053]
In the one-stage compression molding method, the shape and structure of the female mold and the male mold are not particularly limited as long as the bottomed body and mouth can be molded, but generally, as a male mold, Using a core mold and a driven mold provided around the core mold so as to be openable and closable coaxially with the core mold, a bottomed taper portion between the core mold and the female mold (cavity mold) It is desirable that the mouth part is formed by the core mold and the driven mold.
In this case, the driven mold is driven back and forth together with the core mold, but the driven mold is always urged toward the female mold by an urging means such as a spring, but the bottom dead center of the core mold. The core mold and the driven mold are always kept in a constant contact state.
For this reason, even when there is a slight variation in the amount of molten resin, the preform always has a constant height (height from the bottom inner surface to the top of the mouth) and the mouth shape that is important for sealing is always constant. Will be formed. Moreover, the fluctuation | variation of the quantity of a molten resin lump can be absorbed now by providing an annular groove in the lower surface of a support ring as shown, for example in Unexamined-Japanese-Patent No. 10-337769.
[0054]
The one-stage compression molding method has an advantage that the molding force itself is generally considerably small even if a certain amount of pressure is required to prevent sink marks during molding. For this reason, compared with an injection molding apparatus, there exists an advantage that apparatus itself can be reduced in size considerably and apparatus cost can be reduced.
[0055]
A blow molding preform according to the present invention is formed by compression molding of a molten resin material, and includes a mouth portion having a shape and a dimension corresponding to a mouth portion of a final molded body, and a bottomed body portion to be blow-molded. However, the closed bottom portion is characterized by substantially no flow orientation distortion and no gate portion.
[0056]
The gate part existing in a bottomed preform for injection molding has many problems in terms of productivity, manufacturing cost, and the characteristics of the final blow molded product. In the preform of the present invention, this gate is a problem. Since there is no part, the cutting process is unnecessary, there is no generation of scrap resin, and the center of the bottom is smooth and uniform, and there is no cause of whitening due to excessive crystallization There is.
Further, as already pointed out, in the preform having the multilayer structure of the present invention, the inner and outer layers, the gas barrier resin intermediate layer or the adhesive resin layer are continuous even in the center of the bottom, and there is no occurrence of disorder in each layer. There are advantages.
[0057]
When the above preform for blow molding is used, there is no flow orientation distortion or gate at the bottom, and there is no wrinkle, and the smoothness and the uniformity of the structure are outstanding. Blow molded products have the advantage that they are remarkably excellent in appearance characteristics and impact resistance at the bottom.
[0058]
In addition, this preform has the advantage that the degree of thermal deterioration of the resin is small as described above, and a blow molded product excellent in various physical properties such as tensile strength, pressure strength, impact resistance, and heat resistance can be produced. ing.
[0059]
[Compression molding equipment]
In FIG. 1 (side view) showing an example of the arrangement of the entire apparatus used in the one-stage compression molding method, this apparatus is roughly divided into a molten resin lump extrusion supply device 10, a cavity mold 20 for compression molding, and compression molding. It consists of a core mold 30 for use.
[0060]
As shown in FIG. 2, the molten resin lump extrusion supply apparatus 10 includes an extruder main body 11a for melting and kneading the inner and outer layer resins, an extruder main body 11b for melting and kneading the gas barrier intermediate layer resin, and the intermediate layer resin. It is equipped with an extruder main body 11c for melt-kneading the cutting resin, and a vacuum for holding the powder or pellets of the resin to be molded in a dry state and supplying it to the extruder main body on the inlet side Hoppers 12a, 12b, and 12c are provided, respectively.
The die 13 to which these extruders are connected is provided with an inner / outer layer resin passage 14a, an intermediate layer resin passage 14b, and an intermediate layer resin cutting resin passage 14c. The resin passages 14a, 14b, 14c are They are merged in the extrusion passage 15.
Intermittent pressure mechanisms 16b and 16c are provided between the intermediate layer resin extruder 11b and the intermediate layer resin passage 14b and between the intermediate layer resin cutting resin extruder 11c and the intermediate layer resin cutting resin passage 14c, respectively. The intermediate layer resin is covered with the inner and outer resin layers and dropped into the inner and outer layer resins by intermittently extruding the gas barrier intermediate layer resin and further extruding the intermediate layer cutting resin at a timing. An encapsulated extrudate is formed.
Here, when an adhesive resin is required, as shown in FIG. 3, an extruder body 11d for melt-kneading the adhesive resin, a vacuum hopper 12d for supplying the adhesive resin to the extruder body 11d, and a die 13 An adhesive resin passage 14d that merges in the extrusion passage 15 is provided.
Further, an intermittent pressurization mechanism 16d is provided between the adhesive resin extruder 11d and the adhesive resin passage 14d to intermittently extrude the gas barrier intermediate layer resin and the adhesive resin almost simultaneously, and further measure the timing. By intermittently extruding the layer cutting resin, the intermediate layer resin is covered with the adhesive resin layer, and an extrudate encapsulated in a drop shape in the inner and outer layer resins is formed.
When the same resin as the inner and outer layer resins is used as the intermediate layer resin cutting resin, the inner and outer layer resin extruder 11a, the vacuum hopper 12a, and the inner and outer layer resin passages 14a may be omitted.
[0061]
In this state, as shown in FIG. 1, the molten resin lump 17 is pushed out from the die lip 18, but a pair of cutters 19 are provided in the vicinity of the die lip so that the molten resin lump 17 is made of a drop-shaped intermediate resin. Cut at a position close to the bottom edge.
The cavity mold 20 includes a cavity 21 for forming a preform body and a closed bottom.
The core mold 30 includes a core part 31 inserted into the cavity 21, a mouth part disposed above and around the core part 31, and a neck part molding die 32 for neck part molding, and can be moved up and down. It has become. The neck forming die 32 can be opened and closed in the horizontal direction.
[0062]
FIG. 1 shows a molten resin lump extrusion step (A), a molten resin lump cutting and supplying step (B), a compression molding step (C) for multilayer preform molding, and a multilayer preform cooling step (D) for each apparatus. Shown with placement.
[0063]
First, in the molten resin lump extrusion step (A), as described in FIG. 2, the molten resin lump 17 is extruded from the die lip 18.
[0064]
In the molten resin lump cutting and supplying step (B), the molten resin lump extrusion supply device 10 and the cavity mold 20 are positioned on the same axis, and the cutter 19 is operated at this position to separate the molten resin lump 17; It is put into the cavity 21 of the cavity mold 20.
[0065]
In the compression molding step (C) for the multilayer preform molding, the core mold 30 and the cavity mold 20 are positioned on the same axis, and the core mold 30 is lowered so that the molten resin mass 17 in the cavity is multilayered. Compression molding into a preform.
[0066]
In the multilayer preform cooling step (D), the cavity mold 20 and the core mold 30 are forcibly cooled from the inside, and the molded multilayer preform is supercooled to an amorphous state.
After the cooling is completed, the core mold 30 is raised, the preform is extracted from the cavity mold 20, and the neck mold 32 is opened and removed from the core mold 30.
[0067]
In the specific example shown in FIG. 1, in the molten resin lump cutting and supplying step (B), the molten resin lump extrusion supply device 10 and the cavity mold 20 are located on the same axis, and the cutter 19 is operated at this position. The molten resin lump 17 is cut off and directly put into the cavity 21 of the cavity mold 20. However, the cut molten resin lump can be held by a holding member and put into the cavity mold 20.
[0068]
In FIG. 4 (side view) showing another example of the overall arrangement of the apparatus used in the one-stage compression molding method, this apparatus is roughly divided into an extrusion supply apparatus 10 for a molten resin mass, a cavity mold 20 for compression molding, and a compression. It comprises a molding core mold 30 and a molten resin lump holding and conveying device 40.
FIG. 4 includes a molten resin mass extrusion step (A1), a molten resin mass conveyance step (A2), a molten resin mass supply step (B ′), a compression molding step (C) for multilayer preform molding, and a multilayer preform. The cooling step (D) is shown along with the arrangement of each device.
The compression molding step (C) and multilayer preform cooling step (D) for multilayer preform molding in FIG. 3 are basically the same as those described with reference to FIG.
[0069]
In the molten resin lump extrusion step (A1), the molten resin lump 17 is separated by the cutter 19 while the holding and conveying device 40 is positioned below the cutter 19, and the molten resin lump 17 is immediately held and conveyed by the holding and conveying apparatus. 40, and enters the molten resin lump conveying step (A2). In the molten resin lump supply step (B ′), the molten resin lump 17 is conveyed by the holding and conveying device 40 so as to be positioned coaxially with the cavity mold 20, and the holding and conveying device 40 is opened at this position, whereby the molten resin lump is supplied. The lump 17 is released and is dropped into the cavity 21 of the cavity mold 20 by free fall.
[0070]
In FIG. 5 showing the cross-sectional structure of the preform thus formed, the multilayer preform 3 includes a mouth and neck portion 4, a trunk portion 5, and a closed bottom portion 6. The closed bottom 6 is smooth and has no gate. The body 5 and the bottom 6 are composed of an inner layer 1a, an outer layer 1b, and a gas barrier resin intermediate layer 2 enclosed between them, while the mouth 4 is formed of only the inner / outer layer resin 1.
FIG. 7 shows a case where an adhesive resin layer is provided between the inner and outer layers and the gas barrier resin intermediate layer. This multilayer preform 3 'is composed of a mouth portion 4', a body portion 5 ', and a closed bottom portion 6'. The closed bottom 6 'is smooth and does not have a gate. The body 5 'and the bottom 6' are composed of an inner layer 1a ', an outer layer 1b' and a gas barrier resin intermediate layer 2 'and an adhesive resin layer 7 enclosed between them, while the mouth 4' It is formed only by the inner / outer layer resin 1 ′.
[0071]
[Molding condition]
The melt extrusion temperature of the resin (die head temperature) varies depending on the type of resin. For example, in the case of a polyester resin, Tm + 10 ° C. to Tm + 100 ° C., particularly Tm + 20 ° C. to Tm + 40 ° C., based on the melting point (Tm) of the resin. It is preferable that it exists in the range.
If the temperature is lower than the above range, the shear rate may become too high to form a uniform melt extrudate, whereas if the temperature is higher than the above range, the degree of thermal degradation of the resin will increase. Or the drawdown tends to be too large.
[0072]
The weight of the molten resin mass to be cut, that is, the basis weight, is naturally determined by the shape of the final blow bottle. Generally, an appropriate value is selected from the range of 2 to 100 g, particularly 10 to 65 g depending on the required strength. It is good.
[0073]
In addition, it is advantageous in terms of handling that the molten resin mass has a cylindrical shape or a shape close thereto, but the ratio (H / D) of the diameter (D) to the height (H) of the molten resin mass is generally 0. The range of .8 to 4 is advantageous in that the temperature drop of the molten resin lump is prevented as much as possible and the molten resin lump is easily put into the female mold.
That is, when the H / D is out of the above range, the surface area of the molten resin lump becomes large, and the temperature tends to decrease.
[0074]
An arbitrary cutter is used for cutting the molten resin lump, but one that can prevent the resin from sticking is suitable. For example, surface treatment such as shot blasting of the tool surface is particularly effective.
[0075]
The gripping member for moving the molten resin lump is required to have releasability to prevent excessive cooling of the contact surface with the molten resin lump and to smoothly put into the mold. For example, surface treatment such as shot blasting on the surface of the gripping member, or the shape of the gripping member surface in which the contact area with the resin is minimized is important.
It is good to carry out from the cutting of the molten resin lump to the mold as soon as possible and within the time already pointed out.
[0076]
As the compression mold, one having a fine gap or porous part formed at the bottom or in the vicinity thereof is used, and the fine gap divides the bottom of the female mold or the vicinity into several pieces, and these pieces are used. It can be formed by forming a fine gap for excluding air between them or by forming a hole for excluding air in the mold. The porous portion can be used by, for example, processing a sintered metal or the like.
[0077]
The surface temperature of the compression mold may be a temperature at which the molten resin is solidified. For example, in the case of polyester, a temperature range of 10 to 65 ° C. is appropriate. In order to maintain the surface temperature of the mold within the above range, a medium such as cooling water or conditioned water may be passed through the mold.
[0078]
One of the features is that the molding force required for compression molding may be quite small. The specific molding force varies considerably depending on the type of resin and the size of the preform for blow molding, but generally a molding force of 5 to 80 MPa, particularly 8 to 20 MPa is appropriate.
[0079]
The one-stage compression molding described above yields a blow molding multilayer preform that does not have flow orientation distortion at the bottom and does not require any gate or other trimming operations. It can be used in the process and has many advantages in terms of simplification of the process and productivity.
[0080]
The above preform can be used for stretch blow molding as it is, and in order to give heat resistance and rigidity to the mouth part of the preform, the mouth part may be crystallized by heat treatment and whitened at the stage of the preform. Alternatively, after the preform is formed into a bottle by biaxial stretch blow molding described later, the mouth portion of the obtained plastic bottle may be crystallized and whitened.
[0081]
[Stretch blow molding]
The multilayer preform is heated to a stretching temperature, and the preform is pulled and stretched in the axial direction and blown and stretched in the circumferential direction to produce a multilayer bottle.
The molding of the multilayer preform and its stretch blow molding can be performed by a cold parison method, and can also be applied to a hot parison method in which stretch blow molding is performed without completely cooling the preform by compression molding.
[0082]
Prior to stretch blow molding, if necessary, the preform is preheated to a stretchable temperature by means of hot air, an infrared heater, high frequency induction heating or the like. In the case of polyester, the temperature range is 85 to 120 ° C., particularly 95 to 110 ° C.
[0083]
This multilayer preform is supplied into a publicly known stretch blow molding machine, set in a mold, stretched in the axial direction by pushing a stretching rod, and blow stretched in the circumferential direction by blowing fluid. To do.
[0084]
The draw ratio in the final bottle is suitably 1.5 to 25 times in terms of area magnification, and among these, the draw ratio in the axial direction is 1.2 to 6 times, and the draw ratio in the circumferential direction is 1.2 to 4.5. It is better to double.
[0085]
The stretch blow molded bottle can be heat-set by a means known per se. The heat setting can be performed by a one mold method in a blow molding die, or can be performed by a two mold method in a heat fixing die separate from the blow molding die. The temperature for heat setting is suitably in the range of 120 to 180 ° C.
[0086]
In FIG. 6 which shows the biaxial stretch blow molding multilayer bottle by this invention, this bottle 50 consists of the mouth part 51, the trunk | drum 52, and the bottom 53, and the trunk | drum 52 and the bottom 53 are the inner layer 1a, the outer layer 1b, and these It consists of a gas barrier resin intermediate layer 2 enclosed in between. The mouth portion 51 is formed of only the inner and outer layer resins as in the multilayer preform. Since this bottle is formed by compression molding and is formed from a multilayer preform having no gate portion, the inner layer 1a, the outer layer 1b, and the gas barrier resin intermediate layer 2 are not disturbed at all even at the center of the bottom portion. It should be noted.
[0087]
In FIG. 8 showing a biaxially stretched blow molded multilayer bottle according to the present invention, this bottle 50 'is composed of a mouth part 51', a body part 52 'and a bottom part 53', and the body part 52 'and the bottom part 53' are inner layers. 1a ', outer layer 1b', gas barrier resin intermediate layer 2 'enclosed between them, and adhesive resin layer 7 between the inner and outer layers and gas barrier resin intermediate layer 2'. The mouth portion 51 ′ is formed of only the inner and outer layer resins as in the multilayer preform. Since this bottle is formed by compression molding and formed from a multilayer preform having no gate part, the inner layer 1a ′, the outer layer 1b ′, the gas barrier resin intermediate layer 2 ′ and the adhesive resin are also formed at the center of the bottom part. It should be noted that the layer is not disturbed at all.
[0088]
【Example】
The invention is further illustrated by the following examples.
(Example 1)
A polyester resin having an intrinsic viscosity of 0.74 dL / g is used as the inner / outer layer resin, MX nylon resin (MX6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) is used as the gas barrier resin, and the above polyester is used as the gas barrier resin intermediate layer cutting resin. A polyester resin similar to the resin was used.
Then, the molten resin mass is extruded by the extrusion supply apparatus shown in FIG. 2, the ratio of the gas barrier resin is 5% per total weight, and the ratio of the polyester resin which is the gas barrier resin intermediate layer cutting resin is 10 per total weight. % So that the center position of the gas barrier resin in the inner and outer layer resin is 3/4 from the top in the length direction of the cylindrical molten resin lump. A cylindrical molten resin lump having a length of about 72 mm and a diameter of about 22 mm was prepared after being adjusted.
This cylindrical molten resin lump is supplied to the compression molding process shown in FIG. 4 and subjected to compression molding, and a two- and three-layer preform having a basis weight of 32.0 g with polyester resin as inner and outer layers and MX nylon resin as an intermediate layer. Got.
Next, this preform was heated to 110 ° C. by an infrared heater, and a biaxial stretch blow molding was performed in a blow mold heated to 60 ° C. under a condition of a stretching ratio of 2.3 × width 2.6. The inner layer resin had a thickness of 75 μm, a height of 200 mm, a maximum barrel diameter of 60 mm, and a multilayer bottle with an inner volume of 500 ml.
At this time, the gas barrier resin layer was present in a radially inward direction with respect to the thickness direction center of the vessel wall.
[0089]
(Example 2)
In Example 1, the same multilayer bottle was obtained except that the supply amount of the MX nylon resin as the gas barrier resin was 1% per total weight and the thickness of the inner layer resin was 83 μm.
[0090]
(Example 3)
In Example 1, the gas barrier resin was 15% EVAL (EP-F101 manufactured by Kuraray Co., Ltd.) per total weight, and MODEC (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was newly added as the adhesive resin per total weight. 5% was supplied, and a cylindrical molten resin lump in which the outer periphery of the gas barrier resin was enclosed in a model and encapsulated in a polyester resin by an extrusion supply apparatus shown in FIG. 3 was obtained.
This molten resin mass is compression molded by the same compression molding process to make a three-kind five-layer preform, then biaxially stretched blow-molded to make a three-kind five-layer bottle, and the thickness of the inner layer resin is 45 μm. A multilayer bottle similar to Example 1 was obtained.
[0091]
(Comparative Example 1)
In Example 1, except that the supply amount of MX nylon resin was set to 0.5% per total weight, a two-kind / three-layer preform was formed by the same procedure as in Example 1, biaxially stretched blow molding was performed, and the multilayer bottle It was.
[0092]
(Comparative Example 2)
In Example 1, except that the supply amount of MX nylon resin was 18% per total weight, a two-kind three-layer preform was formed by the same procedure as in Example 1, and biaxial stretch blow molding was performed to obtain a multilayer bottle. .
[0093]
(Comparative Example 3)
In Example 1, except that the center position of the MX nylon resin was adjusted to ¼ from the top in the length direction of the cylindrical molten resin lump, the same procedure as in Example 1 was used to perform the two-type three-layer process. Reformation was performed, and biaxial stretch blow molding was performed to obtain a multilayer bottle.
[0094]
(Comparative Example 4)
In Example 1, except that the center position of the MX nylon resin was adjusted to be 2/4 from the top in the length direction of the cylindrical molten resin lump, the same procedure as in Example 1 was used to perform the two-type three-layer process. Reformation was performed, and biaxial stretch blow molding was performed to obtain a multilayer bottle.
[0095]
(Comparative Example 5)
Co-injection was performed using an injection molding machine to obtain a two- and three-layer preform having a basis weight of 32.0 g, in which the same polyester resin as in Example 1 was used as the inner and outer layers and MX nylon resin was the intermediate layer.
The gate part of this preform was cut within 1 mm, and biaxial stretch blow molding was performed in the same manner as in Example 1 to obtain a 500 ml multilayer bottle.
[0096]
[Evaluation test]
1. Formability
Using the preforms in the above Examples and Comparative Examples, the stretch blow moldability at the time of biaxial stretch blow molding, the broken state, and the like were evaluated.
As a result, in Comparative Example 1, the barrier resin layer was partially broken and delaminated, in Comparative Example 2, the gas barrier resin layer was broken without following processing, and in Comparative Example 3, the inner layer was partially broken, Delamination occurred between the barrier resin layers.
These results are shown in Table 1.
[0097]
[Table 1]

[0098]
Next, the multilayer bottles obtained in the examples and comparative examples were cut in the height direction, and the film thickness of each layer was measured from the bottom of the bottle to the bottom of the support ring with a microscope.
In addition, the bottles of Examples 1 to 3 and Comparative Examples 4 and 5 that had no problem in the evaluation of moldability were evaluated with respect to aroma resistance, gas barrier property, and impact resistance.
[0099]
2.Aroma resistance
About each multilayer bottle obtained by the said Example 1 and the comparative example 5 from which the film thickness of an inner layer resin layer differs, after filling 500cc of Japanese tea and nitrogen-substituting a head space, it is the environment of temperature 50 degreeC and relative humidity 80%. It was stored for 1 month, and changes in contents were examined with respect to taste, color, odor and the like.
As a result, in Comparative Example 5, both the odor and taste were changed and browned slightly.
[0100]
3.Gas barrier properties
About each multilayer bottle obtained by the said Example 1 and the comparative examples 4 and 5 whose ratio of gas barrier resin per total weight is 5%, oxygen permeation amount in the environment of temperature 30 degreeC and relative humidity 80% (1 Unit area at atmospheric pressure (1m²The permeated oxygen amount cc) per day was measured.
As a result, the performance of Comparative Example 4 was reduced by about 50% compared to Example 1 because the inner resin layer was thin. Further, in Comparative Example 5, a slight performance degradation was confirmed as compared with Example 1 due to the disturbance of the gas barrier resin layer in the vicinity of the gate portion.
[0101]
4). Impact resistance test
Ten multi-layer biaxially stretched bottles sealed with 500 cc of water were dropped vertically from a height of 120 cm onto a concrete floor, and the number of broken bottles was examined.
As a result, Comparative Example 5 was partially delaminated near the bottom gate.
Table 2 shows the evaluation results of aroma, gas barrier properties and impact resistance.
[0102]
[Table 2]

[0103]
【The invention's effect】
According to the present invention, 1 to 15% by weight of the gas barrier resin is encapsulated in the inner and outer layer resins as an intermediate layer, and the gas barrier resin is continuously provided at the bottom portion. By making the inner wall of the wall deviate from the center in the thickness direction, keep the inner layer resin at a thickness of at least 25 μm, and do not have a gate portion at the bottom, the consistency of the multilayer structure at the bottom can be improved. As a result, a multilayer bottle excellent in gas barrier properties, pressure strength, impact resistance, heat resistance, etc. can be obtained.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of an arrangement of an entire compression molding apparatus used for manufacturing a multilayer bottle of the present invention.
FIG. 2 is a cross-sectional view showing details of an apparatus for extruding a molten resin lump enclosing a barrier resin.
FIG. 3 is a cross-sectional view showing details of an apparatus for extruding a molten resin lump enclosing an adhesive resin and a barrier resin.
FIG. 4 is a side view showing another example of the overall arrangement of the apparatus used in the one-stage compression molding method.
FIG. 5 is a reference cross-sectional view of a multilayer preform used for manufacturing the bottle of the present invention.
FIG. 6 is a reference cross-sectional view of a multilayer biaxial stretch blow molded bottle according to the present invention.
FIG. 7 is a reference cross-sectional view of another multilayer preform used for producing the bottle of the present invention.
FIG. 8 is a reference cross-sectional view of another multilayer biaxial stretch blow molded bottle according to the present invention.

Claims (4)

  A multi-layer bottle formed by biaxially stretching blow-molding a test tube-shaped multi-layer preform obtained by compression molding, wherein 1 to 15% by weight of a gas barrier resin is intermediate in the inner and outer layer resins. The gas barrier resin intermediate layer is continuous at the bottom, but the intermediate layer is not present at the mouth, and the intermediate layer is the center in the thickness direction of the vessel wall. A multilayer bottle characterized in that the inner layer resin is more biased in the radially inward direction and the inner layer resin has a thickness of at least 25 μm.   The inner and outer layer resin is a polyester resin or an olefin resin, and the gas barrier resin is at least one selected from the group consisting of an ethylene vinyl alcohol copolymer, a polyamide resin and a cyclic olefin copolymer. The multilayer bottle according to claim 1.   2. The adhesive resin layer of 1 to 15% by weight per whole is provided between the inner and outer layers and the gas barrier resin intermediate layer, and the adhesive resin layer is continuous at the bottom. Or the multilayer bottle of 2.   A molten resin lump encapsulated in a state where the gas barrier resin is decentered downward in the inner and outer layer resins is supplied to a cavity mold and compressed by a core mold to form a test tube-shaped multilayer preform. The method for producing a multilayer bottle according to claim 1, wherein the preform is biaxially stretch blow molded.

Images