JP2006168290A - Multilayer molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer molding which is excellent in the bonding strength between the layers without use of an added material such as an adhesive and which does not cause interlayer delamination. <P>SOLUTION: In the multilayer molding at least comprising a first resin layer mainly composed of a first polymer material and a second resin layer mainly composed of a second polymer material, the first polymer material has a higher melt viscosity at a predetermined temperature compared with the second polymer material and in the interlayer between the first resin layer and the second resin layer there is formed entanglement of the polymer chain composing the first resin layer and the polymer chain composing the second resin layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer molded body comprising resin layers having different physical properties.

  For example, when a multilayer bottle is formed by a direct blow molding method, a die 20 as shown in FIG. 3 is used. This die 20 is a spider head for two types and three layers of multilayer blow molding, to which two extruders 21 and 22 for supplying two types of molten resin materials are connected. A cylindrical parison (multilayer molded body) having a multilayer structure is formed by coextrusion of two kinds of resin materials.

  In the multilayer molded body molded by the above conventional method, an adhesive should be used to compensate for the lack of adhesive strength between layers, particularly in the case of laminated molded products of different materials in order to improve barrier properties and chemical resistance. There are many.

  However, for example, when a multilayer molded article is used as a pharmaceutical container or food container having improved barrier properties and chemical resistance, use of an adhesive or the like may be restricted from the viewpoint of safety or the like. On the other hand, if an adhesive is not used, delamination occurs. In particular, in pharmaceutical containers and food containers that require transparency, poor appearance cannot be ignored, and the product value may be lost.

  Therefore, an object of the present invention is to provide a multilayer molded article that is excellent in bonding force between layers and does not cause delamination without using an additive material such as an adhesive.

  In order to achieve the above object, the present invention takes the following technical means.

  That is, the present invention provides a multilayer molded body having at least a first resin layer mainly composed of a first polymer material and a second resin layer mainly composed of a second polymer material. The polymer material has a higher melt viscosity at a predetermined molding temperature than the second polymer material, and does not have an interface between the first resin layer and the second resin layer. In addition, an entanglement of the polymer chain constituting the first resin layer and the polymer chain constituting the second resin layer is formed. According to this, the first resin layer and the second resin layer are firmly bonded by entanglement of the mutual polymer chains formed between these layers, and delamination is performed without using an additive material such as an adhesive. Is prevented from occurring. In addition, since a material having a high melt viscosity at a predetermined molding temperature as compared with the second polymer material is employed as the first polymer material, The laminated structure can be easily obtained from the mixed resin material of the first and second polymer materials, and a multilayer molded body that can be easily recycled can be provided.

  In addition, the multilayer molded body obtained by the conventionally known coextrusion molding is such that each layer is bonded mainly by intermolecular van der Waals force, and entanglement of polymer chains between layers is formed. However, in the case of a multilayer molded product of different resin materials having different physical properties, insufficient adhesive force becomes a problem. On the other hand, the multilayer molded body of the present invention can obtain a sufficient bonding force between layers as described above.

  The combination of the first polymer material and the second polymer material only needs to have different viscosities in the molten state at the molding temperature, such as phenol resin, urea resin, melamine resin, unsaturated polyester, diallyl phthalate resin. , Epoxy resin, polyurethane, silicon resin, polyimide, vinyl chloride, vinylidene chloride resin, vinyl acetate resin, polyvinyl alcohol, polyvinyl acetal, polystyrene, AS resin, ABS resin, AXS resin, methacrylic resin, polyethylene, EVA resin, EVOH resin, Polypropylene, polybutylene, methylpentene resin, fluororesin, polyamide, polyacetal, polycarbonate, saturated polyester, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, polyethers Sulfone, polyether ether ketone can be selected from a suitable polymeric material such as a thermoplastic elastomer. Preferably, thermoplastic resins are employed as the first and second polymer materials, and in particular, polyolefins such as PET, polyamide, and polyethylene can be employed. The weight ratio between the first polymer material and the second polymer material may be appropriate.

  The entanglement is preferably formed over 0.01 mm or more in the layer thickness direction, more preferably 0.02 mm or more.

  In the multilayer molded body of the present invention, the second resin layer can be laminated on both the front and back sides of the first resin layer. The first resin layer may be formed as a single layer extended over the entire range of the multilayer molded body, and a large number of small first resin layers are dispersedly formed throughout the multilayer molded body. Alternatively, a plurality of first resin layers may be formed in the layer thickness direction. In any case, the second resin layer only needs to be formed on both the front and back sides of the first resin layer, and the present invention even if the second resin layer is sandwiched between the two first resin layers. include.

  In addition, the first and second resin layers are formed into an annular flow when extruding a molten mixed resin material containing the first polymer material and the second polymer material from a die having an outer mold and an inner mold. The outer mold and the inner mold that form the path are relatively rotated, whereby the first polymer material and the second polymer material are separated in the layer thickness direction, and the first and second polymer materials are separated from each other. It can be formed by cooling and solidifying. According to this, the melt-mixed resin material is subjected to a large shear stress due to the relative rotation in the annular flow path of the die, thereby aggregating the first polymer material having a large viscosity in the middle in the layer thickness direction. A mixed layer in which both materials are mixed is formed between these layers while aggregating the second polymer material having a small size on the layer surface side, and the above laminated structure can be easily obtained by cooling and solidifying this. Furthermore, the multilayer molded body can be easily molded using recycled pellets collected after use, washed and pulverized, and becomes a multilayer molded body excellent in recyclability.

  Moreover, in the multilayer molded article of the present invention having a substantially uniform thickness throughout, preferably, the first resin layer is all formed along the in-plane direction of the multilayer molded article. Here, along the in-plane direction means, for example, that a flat multilayer molded body is parallel along the plane, and a cylindrical multilayer molded body has a similar curvature along its peripheral surface. It is curved.

  Further, the multilayer molded body of the present invention may be a cylindrical extrusion molded body, and a predetermined portion in the circumferential direction of the cylindrical multilayer molded body is cut in the axial direction and rolled into a flat plate shape or a film shape. It may be a multilayer molded body, or may be a multilayer molded body formed by blow-molding into a bottle shape using the cylindrical multilayer molded body as a parison. It may be a multilayer molded body having an appropriate form.

  Next, an example of a method for producing the multilayer molded body will be described. The inventors of the present invention simply apply the respective molding materials constituting each layer of the multilayer molded article and apply a shearing force to the melted blend. It is known that the material is separated into the inside and outside and is structured in layers. That is, in extrusion molding, a molten molding material is passed through an annular channel formed between an outer die (such as a die) and an inner die (such as a core) of a die, and is applied in the process of passing the channel. When the molding material flows in the die, the molten resin material is cooled immediately after touching the mold wall surface, and its viscosity increases. As a result, the flowing material immediately inside the material whose viscosity has increased. Is always in shear. At this time, if the molding material is composed of a mixed material having a difference in viscosity at the time of melting, the low-viscosity material moves outside the fluidized bed due to this shear phenomenon, and the high-viscosity material moves inside the fluidized bed (in the layer thickness direction). The phenomenon of trying to shift to the middle part occurs. In addition to such knowledge, the inventors of the present application cannot obtain a good multilayer structure only by the shearing phenomenon that occurs in the molding material when simply extrusion molding. The inventors have found a method in which a strong shearing force is generated by relatively rotating the outer mold and the inner mold at a high speed, and as a result, a laminated extruded product of the mixed material is obtained.

  A novel method for producing a multilayer extrusion molded body based on such knowledge is obtained by melting and kneading two or more resin materials (preferably thermoplastic resin materials) having different viscosities and extruding the melt-mixed resin material from a die. In addition, the outer mold and the inner mold of the die are relatively rotated to form a layer of a resin material having a high viscosity at a predetermined portion in the thickness direction of the annular flow path in the die, A low resin material layer is formed. As the two or more resin materials, a combination of a plurality of thermoplastic resins having different physical properties such as gas barrier properties and chemical resistance can be selected. Here, as the two or more kinds of resin materials, the first and second polymer materials can be used, the high viscosity resin layer becomes the first resin layer, and the low viscosity resin layer becomes the second resin. Become a layer. The high-viscosity resin layer may be formed by forming a plurality of thin high-viscosity resin layers in the layer thickness direction, and having a thickness of 50% or more of the total thickness of the multilayer extruded product. Only one resin layer may be formed.

  As the above-described two or more kinds of resin materials, it is preferable to select a resin material having a low compatibility (that is, an incompatible system combination) at a temperature in the vicinity of the highest melting point among the plurality of resin materials. On the other hand, it is desirable that the molten mixed resin material to be supplied to the annular flow path of the die is a uniform blend obtained by uniformly mixing and melting two or more kinds of resin materials. Different types of polymers are usually difficult to mix, but by adding a compatibilizing agent which is a polymerizable surfactant, a uniform blend having desired properties is easily formed from two or more polymers. In particular, as the compatibilizing agent, those showing a large compatibility at a predetermined temperature or higher are preferable. According to this, at the time when the molten mixed resin material is supplied into the die, the temperature of the molten mixed resin material is set to a temperature that exhibits a high compatibility with the compatibilizing agent, so that the mixed material is mixed in the extruder. It is possible to eliminate the occurrence of the separation phenomenon and supply the molten mixed resin material to the die in a uniform blended state. And when it comes into contact with the mold and cools, it becomes incompatible and can be easily multilayered by applying a shearing force to the resin material in the annular flow path of the die by the relative rotation of the mold. It becomes possible.

  According to the above manufacturing method, it is possible to obtain a multilayer extruded product by using a single extruder and a die having a single annular channel, so that the cost of the multilayer extruded product can be greatly reduced. It becomes possible.

  In general, when the molten mixed resin material passes through the annular flow path while rotating the outer mold and the inner mold relative to each other, the shear force becomes the largest near the mold contact surface, and the center in the thickness direction of the annular flow path is the most sheared. The power is reduced. Therefore, the high-viscosity resin layer is formed at the central portion in the thickness direction of the annular flow path. Further, the relative rotation causes a self-aligning action of the inner mold, and it is possible to obtain a cylindrical extruded body having a uniform thickness in the circumferential direction. In order to produce such a self-aligning action, the thickness of the extruded product (that is, the total thickness including the first and second resin layers) is preferably 2 mm or less.

  Although the molded article manufactured by the said manufacturing method is restrict | limited to a cross-sectional cylindrical thing, the kind of the molded article is not limited to a specific thing. For example, a resin tube having a laminated structure, a cylindrical parison used for direct blow molding, and the like can be formed by the above manufacturing method. That is, in the direct blow molding method to which the above manufacturing method is applied, a pipe-shaped multilayer parison is molded by the above manufacturing method, and this parison is sandwiched between split molds and a part of the parison in the axial direction serving as the bottom of the bottle is fused. At the same time, air is blown into the parison, and the parison is pressed against the inner surface of the split mold by air pressure. Such a direct blow molding method can be easily carried out by those skilled in the art by applying a conventionally known technique except for a method of laminating a parison.

  The above manufacturing method can be carried out by the following manufacturing apparatus. Such a multilayer extrusion molded body manufacturing apparatus includes an extruder for melt-kneading two or more kinds of thermoplastic resin materials having different viscosities, and a die attached to the tip of the extruder, and the die is cylindrical. An outer mold having an inner circumferential surface, an inner mold having a cylindrical outer circumferential surface and disposed on the same axis within the outer mold, and an outer mold and an inner mold are relatively rotated about the axis. A rotation drive mechanism, and an annular flow path is formed between the inner mold and the outer mold in the cross section. According to such a manufacturing apparatus, a layer of a resin material having a high viscosity is formed in a predetermined portion in the thickness direction of the annular flow path having a small shear stress by relatively rotating the outer mold and the inner mold by the rotation drive mechanism, It is possible to form a layer of a resin material having a low viscosity inside and outside the high viscosity resin layer. Moreover, since it can be used as a die for single-layer extrusion if the rotation drive mechanism is not operated, it is also possible to form a single-layer extruded product using such a manufacturing apparatus.

  The rotation drive mechanism can rotate either the outer mold or the inner mold around its axis. According to this, since only one of the outer mold and the inner mold needs to be provided with a rotation drive mechanism, the structure of the apparatus can be simplified, the flow path structure in the die, and the connection structure between the die and the extruder The degree of freedom of design can be increased.

  The molded product of the present invention is preferably a synthetic resin molded product, and the molded product is not only the final molded product, but is further subjected to a molding process such as blow molding or a secondary process such as after baking. Things (such as Parisons) are also included. Moreover, the molded body of the present invention includes not only a three-layer molded body but also a molded body having four or more layers and a two-layer molded body.

  The rotation drive mechanism may adopt any configuration as long as it relatively drives the outer mold and the inner mold to rotate, for example, may rotate both the outer mold and the inner mold. Alternatively, one of the outer mold and the inner mold may be fixed and the other may be rotationally driven. Specifically, for example, the rotation driving mechanism can rotate the outer mold around its axis. Further, the rotation drive mechanism can also rotate the inner mold around its axis. Further, the outer mold and the inner mold can be relatively rotated only in a part in the axial direction of the annular flow path. In this case, two or more types of molten resin materials are separated radially inward and outward in the relative rotational part. However, it is also possible to separate and form the annular flow path for each resin material on the downstream side of the relative rotation portion, and to join the resin material layers when the viscosity increases to some extent.

  As described above, in the present invention, the resin material constituting each layer of the multilayer molded product is melt-mixed in advance, and the melt-mixed resin material is circulated through the annular flow path inside the die in the outer mold and the inner mold. Since the resin materials are dispersed inside and outside due to the difference in viscosity of each resin material and the difference in shearing force inside the annular flow path, a multilayer extrusion molded product can be obtained with a single extruder. Can do. By manufacturing a multilayer resin molded product using such a new manufacturing method and manufacturing apparatus, it is possible to simplify the apparatus configuration and reduce the equipment cost, and to significantly reduce the product cost. In addition, the extrusion molding apparatus of the present invention can achieve a remarkable effect that it is possible to mold both single-layer molded products and multilayer molded products.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a simplified view of the main part of a direct blow molding apparatus 1 using a multilayer parison (multilayer molded body) according to an embodiment of the present invention. The direct blow molding apparatus 1 includes a multilayer extrusion molding apparatus 2 for extruding a cylindrical multilayer parison P, and a blow molding metal for blow molding the parison P immediately after molding by the apparatus 2 to obtain a bottle product. A mold 3 is provided. The bottle product obtained in this way is also an embodiment of the multilayer molded body of the present invention.

  The extrusion molding apparatus 2 includes a crosshead die 4, a single kneading extruder 5 that supplies a molten mixed resin material (molding material) to the die 4, and a pellet raw material to the kneading extruder 5. And a hopper 6 for the purpose. The hopper 6 is supplied with a plurality of resin materials constituting each layer of the multilayer molded product and, if necessary, various additive materials (such as a compatibilizing agent). This combination of resin materials can be variously selected according to the performance, use, etc. required for the molded product. For example, nylon (first polymer material) and polyolefin (second polymer material), PET (first polymer material) and nylon (second polymer material) can be used. In addition, you may provide the hopper 4 for every resin material, and it can also comprise so that melt-kneading may be performed for each resin material and a different resin material may be mixed in a molten state. It is also possible to use mixed pellets obtained by mixing two or more kinds of resin materials.

  The die 4 is connected to the tip of the extruder 5 and is arranged on the same axis in the outer die 7 having a cylindrical inner peripheral surface and the outer die 7 having a cylindrical outer peripheral surface. And an inner mold 8 (core) provided. An annular channel is formed in the cross section between the outer mold 7 and the inner mold 8, and the molding material kneaded and melted by the screw 5 a in the extruder 5 is extruded into the annular channel. Is shaped and cooled, and pushed out from the tip (lower end) of the die 4. In addition, since the molding material extruded from the die 4 instantaneously changes from the pressurized state inside the extruder 5 and the die 4 to the normal pressure state, the molding material swells in the radial direction, and a parison having a predetermined diameter is formed.

  The inner mold 8 is configured to be rotationally driven at high speed by a rotational drive mechanism having a motor 10 and transmission gears 11 and 12. That is, the upper side of the inner mold 8 is rotatably fitted to the upper side of the outer mold 7, and the lower side of the inner mold 8 is configured to have a smaller diameter than the upper side. A gap between the outer mold 7 and the outer mold 7 serves as a flow path for the molding material. The inner mold 8 can also be rotatably supported by a bearing fixed to the outer mold 7. A gear 12 is integrally provided at the upper end portion of the inner mold 8, and a gear 11 that meshes with the gear 12 is provided on the output shaft of the motor 10.

  A blow molding die 3 is disposed below the die 4 described above. The blow molding die 3 is the same as a conventionally known one composed of split dies 3a and 3b and a blow nozzle (not shown), and therefore detailed description thereof is omitted.

  According to the direct blow molding apparatus, it is possible to produce a blow molded article having a multilayer structure by extruding a polymer blend of polyolefin such as polyethylene and nylon from a single extruder. That is, the uniformly blended resin material melted and mixed in the extruder 5 is supplied to the die 4 to flow through the flow path in the die 4. At this time, the motor 10 is driven to rotate the inner die 8 at a high speed. Due to the difference in viscosity between polyolefin and nylon when melted, the high-viscosity nylon moves to the center in the thickness direction of the annular channel, and the low-viscosity polyolefin is located on both outer sides in the thickness direction of the annular channel (the outer circumference of nylon) The mixed resin material is multilayered in the annular flow path. The inner die 8 rotates to cause a self-aligning action in the inner die 8, and a multilayer parison is formed with a substantially uniform thickness in the circumferential direction.

  Then, the molding material is cooled as it reaches the downstream side of the annular channel, and the curing of the molding material proceeds. Therefore, the molding material is pushed out from the tip end of the die 4 in a multilayered state, and a cylindrical multilayer parison (three-layer parison) ) Is formed. The parison which is a multilayer molded body molded in this manner is a first resin mainly composed of nylon formed by agglomeration of nylon (first polymer material) having a high melt viscosity at the molding temperature at the center in the layer thickness direction. While constituting a layer, a polyolefin having a low melt viscosity aggregates on both the front and back sides of the first resin layer to constitute a second resin layer. Further, the interface between the first resin layer and the second resin layer is not clear, and an entanglement between the polymer chain constituting the first resin layer and the polymer chain constituting the second resin layer is formed. It becomes. This entanglement can be formed in the layer thickness direction by 0.1 mm or more by setting various molding conditions, and can also be formed by 0.2 mm or more.

  The parison is sandwiched between the split molds 3a and 3b of the blow mold and a part of the parison in the axial direction (the upper side of the split molds 3a and 3b in the drawing) is fused and the inside of the parison Then, the parison is expanded by air pressure, pressed against the inner surfaces of the split molds 3a and 3b, and cooled and solidified to form a laminated bottle container.

  On the other hand, when manufacturing a single-layer molded product, by stopping the motor 10, a single-layer parison can be molded by the die 4, and the apparatus of the single-layer molded product and the multilayer molded product can be formed. Can be shared.

  Further, since two or more resin materials for obtaining a multilayer structure may be kneaded and melted in a single extruder, the number of extruders can be reduced, and the apparatus cost can be reduced and the entire apparatus can be reduced in size. It is also possible.

  In addition, this invention is not limited to the aspect of the said embodiment, A design change is possible suitably within the range which this invention intends. For example, the die is not limited to a crosshead die, and may have a conventionally known appropriate configuration such as an offset die or a straight die. In the present invention, two or more resin materials may be kneaded and melted in at least one extruder and multilayered in a die, and such multilayered two or more resin materials may be kneaded. It is also possible to provide a conventionally known lining molding material extruder together with a melting extruder.

  It is also possible to obtain a multilayer film or a multilayer plate-shaped molded body by cutting one place in the circumferential direction of the parison P in the axial direction and rolling it into a flat plate or film using an appropriate rolling mill. These multilayer films and multilayer plate-shaped molded products are also included in the multilayer molded product of the present invention.

  Two polymer materials, “MX Nylon 6001”, which is a polyamide manufactured by Mitsubishi Gas Chemical Co., Ltd., and “PET1206”, which is a polyethylene terephthalate manufactured by Unitika Ltd., are PET / PA = 85/15 (wt%). The mixture was mixed at a ratio, and mixed pellets were produced using an extruder. The extrusion conditions of this extruder were a cylinder temperature of 260 ° C. and a screw rotation speed of 30 rpm. When the produced pellet was dyed with a 0.1% glacial acetic acid solution, it was confirmed that the polyamide was uniformly dispersed in the PET.

  The mixed pellets are put into the hopper 6 of the extrusion molding apparatus 2 and extrusion molding is performed under the extrusion conditions of a cylinder temperature of 180 ° C., a screw rotation speed of 60 rpm, an extrusion head temperature of 190 ° C., an extrusion speed of 20 mm / sec, and a core rotation speed of 60 rpm. As a result, as shown in FIG. 2, a multilayer parison having a cross section of a three-layer structure of polyamide layer / PET layer / polyamide layer was obtained.

  The wall thickness of this multi-layer parison is approximately 1.07 mm, the thickness of the polyamide layer constituting the outer peripheral surface side layer (right side in FIG. 2) is approximately 0.12 mm, and the inner peripheral surface side surface layer (left side in FIG. 2) is configured. The thickness of the polyamide layer was about 0.15 mm, and the thickness of the central PET layer was about 0.8 mm. In addition, the interface between the polyamide layer and the PET layer is unclear, and at this interface, both PET and polyamide materials are dispersed over the range of about 0.01 mm to 0.02 mm in the layer thickness direction. Entanglement of molecular chains was formed.

1 is an overall simplified side sectional view of a direct blow molding apparatus for molding a multilayer parison and multilayer bottles according to an embodiment of the present invention. It is a cross-sectional enlarged photograph which shows the cross-section of the multilayer parison based on one Example of this invention. It is a simplified side sectional view of a conventional multilayer extrusion molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Direct blow molding apparatus 2 Multi-layer extrusion molding apparatus 3 Blow molding die 4 Die 5 Extruder 7 Outer mold (die)
8 Inner mold (core)
10, 11, 12 Rotation drive mechanism P Parison (multilayer molded body)

Claims (8)

In a multilayer molded body having at least a first resin layer mainly composed of a first polymer material and a second resin layer mainly composed of a second polymer material, the first polymer material is 2 having a high melt viscosity at a predetermined molding temperature as compared with the polymer material 2, and between the first resin layer and the second resin layer, the polymer chain constituting the first resin layer and the second resin layer A multilayer molded article in which an entanglement with a polymer chain constituting a resin layer is formed. The multilayer molded body according to claim 1, wherein the entanglement is formed over 0.01 mm or more in the layer thickness direction. The multilayer molded body according to claim 1 or 2, wherein a second resin layer is laminated on both front and back sides of the first resin layer. When the molten mixed resin material containing the first polymer material and the second polymer material is extruded from a die having an outer mold and an inner mold, the outer mold and the inner mold forming the annular flow path are rotated relative to each other. Thus, the first polymer material and the second polymer material are separated in the layer thickness direction, and the first and second polymer layers are cooled and solidified to thereby form the first and second resin layers. The multilayer molded body according to claim 1, wherein: is formed. The multilayer molded body according to any one of claims 1 to 4, wherein the thickness is substantially uniform over the entire surface, wherein all the first resin layers are formed along the in-plane direction of the multilayer molded body. A multilayer molded body. The multilayer molded body according to any one of claims 1 to 5, wherein the multilayer molded body is a cylindrical extruded molded body. A multilayer molded body obtained by cutting a predetermined portion in the circumferential direction of the cylindrical multilayer molded body according to claim 6 in the axial direction and rolling it into a flat plate or a film. A multilayer molded body obtained by blow-molding into a bottle shape using the cylindrical multilayer molded body according to claim 6 as a parison.

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