JPH06155561A - Multilayer blow molding method and apparatus, and hollow molded product obtained by the method - Google Patents

Abstract

PURPOSE:To easily produce a blow molded product partially changed in physical properties along the peripheral direction of the cross-sectional surface thereof by forming demarcation areas mutually different in either one or more of the kinds of resins, the number of layers and layer thickness along the circumferential direction of a parison. CONSTITUTION:When the number of the demarcation areas formed along the circumferential direction of a parison is set to (p), a multi-torus 1 has a flow passage 1a developing the molten resins flowing in from (m) inflow ports in an m-layered structure in a concentric circular state. A Lotus route part 2 has a flow passage 2a distributing respective molten resins into the patterns of preset m-kind n-layered (p) sections and an octopath part 3 has a passage guiding the molten resins developed on the m-layered concentric circular passages 1a of the multi-torus part 1 so as to direct them to the pattern passages 2a of m-kind n-layered (p) sections demarcated corresponding to the kinds of the resins by the lotus route part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel multi-layer blow molding method, an apparatus for carrying out this method, and a hollow molded article obtained by this method. More specifically, in addition to having a multilayer structure of at least two layers in the thickness direction,
A multilayer blow molding method for molding a hollow molded article having at least two or more different resin regions along the peripheral wall in any of the layers constituting this multilayer structure, and for carrying out this method. The present invention relates to a multi-layer blow molding device used for, and further relates to a hollow molded article molded by this method.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made regarding a method and an apparatus for producing a hollow molded article having a plurality of layers made of a plurality of kinds of thermoplastic resins by blow molding or a hollow molded article obtained. The following are specific examples of the form of the formed multi-layer parison. That is, in Japanese Examined Patent Publication No. 52-37,026 and Japanese Examined Patent Publication No. 57-53,175, for example, as shown in FIG. 38, the resin species A and B are formed concentrically in the cross-sectional shape. A shape having the resin layers 1 and 2, and the thickness ratio of each of the resin layers 1 and 2 is uniform over the entire length, that is, in the longitudinal direction (discharging direction during extrusion) and the circumferential direction. The multi-layer parison P is disclosed. By carrying out multi-layer blow molding using such a multi-layer parison P, it is possible to blow-mold gasoline tanks of automobiles, mayonnaise and ketchup containers to be consumed by ordinary households. It's actually done.

In Japanese Patent Laid-Open No. 62-138,227 and Japanese Patent Laid-Open No. 2-113,908, which is called a priority multi-layer blow system, for example, as shown in FIG. As in the case of FIG. 38, the resin layers 1 and 2 are formed concentrically with the resin species A and C, respectively, and between these resin layers 1 and 2, another region is provided in a predetermined region in the parison longitudinal direction. A multi-layer parison P provided with a resin layer 3 of a resin type B is disclosed, and it is described that such a multi-layer parison P is blow-molded to mainly form an automobile gasoline tank.

Further, Japanese Utility Model Laid-Open No. 63-101,512 and Japanese Utility Model Laid-Open No. 63-106,984, which are called a connection blow method, for example, as shown in FIG. Similar to the case, the resin layers 1 and 2 are formed concentrically by the resin species A and B, respectively, and the wall thickness ratio of these resin layers 1 and 2 changes along the parison longitudinal direction. A multi-layer parison P is disclosed, and it is described that such a multi-layer parison P is blow-molded to form intake system ducts mainly arranged in an engine room of an automobile. In FIG. 40, the thickness of the resin layer 1 is thicker than that of the resin layer 2 at the upper and lower ends of the parison, and the thickness of the resin layer 2 is thicker than that of the resin layer 1 at the central portion. Although an example of a thicker multilayer parison is shown, the pattern of the change in the thickness ratio of the resin layer is not limited to this, of course.

Further, Japanese Patent Publication No. 2-15373 discloses a blow molding method called exchange blow method, which is mainly arranged in the engine room of an automobile as in the case of FIG. For example, as shown in FIG. 41, a multi-layer parison P formed by sequentially changing resin species A, resin species B and resin species A from one end in the longitudinal direction of the parison is disclosed for the purpose of molding the intake ducts. Has been done. Furthermore, in Japanese Utility Model Laid-Open No. 3-57,020 according to the invention of one of the inventors of the present invention,
The parison is vertically divided along the longitudinal direction at the center of its cross section to form a half-sided structure having a two-layer structure in which two kinds of resin are laminated, and the other half has a single-layer structure composed of one kind of resin. Discloses a multi-layer parison having the same layer structure over the entire length in the longitudinal direction of the parison, and states that it is convenient for forming a container for containing and carrying various articles.

[0006]

However, in a parison having such a layer structure, as will be described later, as soon as the parison exits from the die head, it shrinks to a single layer side and becomes wrinkled.
As shown in, it cannot be a very molding parison. In addition, this method is a very unique method of blow molding using a mold divided into seven parts, and the molded product also has a very special double-wall structure with deep drawing. However, there is a problem that it cannot be applied to blow molding of other shapes. Moreover, in Japanese Utility Model Laid-Open No. 3-57,020,
Actually, no specific method or mechanism for forming such a multi-layer parison is shown.

By the way, the physical properties of the hollow molded article obtained by blow molding mainly depend on the properties of the thermoplastic resin used therein. Therefore, the molded product has different physical properties in each area of its part depending on the use and place of use of the molded product, and satisfying the physical properties required in each area is the quality of the molded product. Is extremely important for improving

For example, in the case of an automobile bumper, its fascia portion is required to be beautiful in appearance, and its beam portion is required to have a strength capable of withstanding an impact such as a collision. Also, in the case of a seat or backrest of a chair, the surface-side part is the part that is directly contacted by the person, so it is highly elastic and has a soft touch and is a non-slip material. Is required to be
Further, since the back side portion thereof is fixed to a skeleton such as a leg of a chair to support the weight of a seated person, it is essential to have excellent strength and rigidity.

Further, in the case of a door of a boiler room, its front side is exposed to the outside, so that it is required to have an excellent appearance, and its back side is filled with high-temperature steam or steam. Since it shields an atmosphere in which oil droplets are also floating, heat resistance, hot water resistance, oil resistance, etc. are required.Furthermore, the upper and lower end parts of them are attached to a sill or duck. Since it is opened and closed while being in contact with the rail, it is required to have excellent abrasion resistance and heat resistance. Therefore, in these molded products, a resin suitable for satisfying the role of each part and the physical properties required for the part is selected, and the whole is integrally molded. Is desirable.

In the case of producing such a molded product by blow molding, it is not possible to deal with the multilayer parison by simply making the multilayer in the thickness direction thereof. It is indispensable to form a plurality of partitioned regions having different thicknesses, and it is also necessary to form multiple layers in the thickness direction of the parison and to partition with different kinds of resin in the circumferential direction of the parison. However, in the conventional multi-layer blow molding method described above, even though it is possible to form multiple layers in the thickness direction of the parison, it is not possible to compartmentalize the different types of resin in the circumferential direction of the parison. It has not been possible to mold these molded products by using a plurality of resins having physical properties required according to the role of the resin.

Therefore, in the prior art, for example, in the case of an automobile bumper, there is no method other than separately manufacturing the fascia portion and the beam portion, and these are integrally manufactured as a single component. However, there is a problem that it is impossible to reduce the cost. Also,
Looking at the seat and backrest of the chair, there is no other choice than to separately mold the front side part and the back side part and then combine these parts, as it cannot be manufactured integrally in a single process. The cost is high and there is a problem in strength.

Therefore, an object of the present invention is to have partition regions which are different from each other in at least one of the resin type, the number of layers and the layer thickness along the peripheral wall of the cross section of the molded product, and among the formed partition regions. The one having the minimum width is a partition region of different resin species having a width of ⅛ or more of the entire circumference of the peripheral wall of the molded product in any one resin layer and extending along the vertical cross-sectional wall of the molded product. It is an object of the invention to provide a method, an apparatus and a hollow molding product for producing a multi-layer blow-molded product in which each compartment region corresponds to a role of each of the regions that the hollow molding product should have.

Another object of the present invention is to have partition areas which are different from each other in at least one of the resin type, the number of layers and the layer thickness along the peripheral wall of the cross section of the molded product, and each partitioned area. The wall thickness ratio of the resin layer in is changing along the vertical wall of the molded product, and the wall thickness change along each of the above-mentioned partitioned regions and the vertical wall of the molded product has a role in each of the regions that the hollow molded product should have. It is an object to provide a method, an apparatus and a hollow molding of this kind for producing a corresponding multilayer blow-molded article.

Still another object of the present invention is, for example, in a hollow molded article such as a bumper for an automobile, a seat portion or a back portion of a chair, a door of a boiler room, etc., each of which has a plurality of partitioned regions of different resin types. However, it is to provide a multilayer blow-molded product in which each partitioned region corresponds to each role of each region that the hollow-molded product as a product should have.

[0015]

First, according to the present invention, a plurality of thermoplastic resins are extruded in a cylindrical shape from a die head to form a multilayer structure over the entire circumference thereof, and the entire thickness thereof is Form a multi-layer parison that is substantially uniform, and then guide this extruded multi-layer parison into multiple open molds that can be received by the parison and clamp the mold to blow mold it. When performing the above, regarding the above-mentioned multi-layer parison, different partition regions are formed along the circumferential direction of the parison with respect to any one or more of the resin type, the number of layers, and the layer thickness, and at the same time among the formed partition regions. One of the narrow resin layers is 45 in the parison circumferential direction.
It is a multi-layer blow molding method characterized in that it is a partitioned region of different resin species extending in the parison longitudinal direction having a partition width of an angle of 0 ° or more.

In this method, the outermost layer of the multi-layer parison is a layer that primarily defines the partitioned areas of different resin species, and the mold corresponds to the partitioned areas of different resin species. And is divided into multiple mold components,
When performing blow molding by clamping these mold constituents, the boundary portions of the partitioned areas of different resin species are cut off by the abutting portions of these mold constituents, and the resin along the ridge line of the corner of the molded product is cut. By matching the boundaries of the partitioned regions of different types, it is possible to reliably prevent the boundaries of the partitioned regions of different resin types from deviating from the ridges of the corners of the molded product and impairing the appearance.

In the multilayer blow molding apparatus for carrying out the first method, a plurality of thermoplastic resins are extruded in a cylindrical shape from the die head to form a multi-layer over the entire circumference and the entire meat. Form a multi-layer parison with a substantially uniform thickness, and guide this extruded multi-layer parison into multiple open molds that can be received by the parison and clamp and blow the mold. A device for molding, the die head, a multi-torus portion that expands a plurality of molten resins extruded from an extrusion device into concentric annular flow paths, and for each resin layer that constitutes a multi-layer parison in the parison circumferential direction. A lotus root portion that constitutes a flow path for forming partitioned areas of different resin species along the
An octopus part that forms a flow path connecting between the multi-torus part and the lotus root part, and a nozzle part that is located below the lotus root part and discharges the multi-layer parison. The number of resin species to be formed is m (however, 8 ≧ m ≧ 2 is an integer), the number of layers of the extruded multilayer parison is n (however, n ≧ 2 is an integer), and When the number of partitioned regions formed along the parison circumferential direction with respect to any one or more of the resin type, the number of layers, and the layer thickness is p (provided that p ≧ 2 is an integer), the multi-torus portion is m. There is a flow path for expanding the molten resin flowing in from each of the inflow ports in an m-fold concentric annular shape, and the lotus root part distributes each molten resin in a preset pattern of m kinds of n layers p sections. Have and above the octopus part In order to have a flow path that guides the molten resin developed in the m-thick concentric annular flow path in the multi-torus part to the pattern flow path of m-type n-layer p-partitioned by the lotus root part according to the resin type Can be configured as a simple device.

In this multi-layer blow molding apparatus, the multi-torus part, the lotus root part, the octopus part and the nozzle part which constitute the die head are each composed of independent parts so that these parts can be easily disassembled and assembled. As a result, various shapes of the lotus root portion are selected, and the resin species of the molten resin to be supplied to the multi-torus portion and the number thereof are appropriately selected. By forming a multi-layer parison having various layer configurations for p, it is possible to appropriately meet the needs required for various hollow molded articles by using this.

In this multi-layer blow molding device,
The m types of n layers (however, in this case, n ≧ 3 or more integers) p
A m'type n'layer p'section (where m ', n'and p'are all 2 or more, m ≧ m', n> using a die head for discharging a multi-layer parison of the section) n ′ and p ≧
For the lotus root portion used when forming a multi-layered parison satisfying the condition of p ′, for closing the channel lower end opening of nn ′ layers from the outside of the pattern channel having n layers thereof. By preparing a removable blind ring, the same multi-torus part, lotus root part,
A die head equipped with an octopus part and a nozzle part can be used to form a multilayer parison with a smaller number of layers,
A multi-layer blow molding device for multipurpose use can be constructed.

Therefore, according to the multi-layer blow molding apparatus thus constructed, a plurality of thermoplastic synthetic resins, which are separately heated and melted, are merged in the die head portion,
The number of resin species, the number of layers n, and the number of partitions in the parison circumferential direction p are varied through a slit having a circular shape, an elliptical shape, or a shape obtained by deforming a circle such as a combination of an arc and a straight line in the nozzle portion located at the tip of the die head. Extruding a multi-layer parison having a pattern of, the hollow molded article has a plurality of partitioned areas of different resin types from the multi-layer parison, and the resin constituting each of these partitioned areas plays a role of each area in the hollow molded article. It is possible to produce various multilayer blow-molded articles that exhibit physical properties according to the above.

That is, the multilayer blow-molded product molded by the first method and apparatus as described above is a multi-layered product having a plurality of thermoplastic resins extruded in a cylindrical shape from a die head and having a multi-layered structure over the entire circumference thereof. Is a hollow molded article formed by blow-molding a multilayer parison having a substantially uniform wall thickness, and this hollow molded article has a cross section along the peripheral wall of the molded article. The resin has a partition region different from each other in any one or more of the resin type, the number of layers, and the layer thickness, and the one having the smallest width among the formed partition regions is formed on the peripheral wall of the cross section of the molded product in any one resin layer. It is a partition region having a width of at least ⅛ or more of the entire circumference and extending along the wall of the vertical cross section of the molded product, and each of the partitioned regions has a role of each region that the hollow molded product should have. Corresponding structure Going on.

Therefore, the multilayer blow-molded article molded by this method and apparatus is, for example, a bumper for automobiles, and the fascia portion corresponding to the outer surface of the article has a physical appearance that is beautiful. For example, to select a resin such as ABS resin, and to impart a property that the beam portion corresponding to the inside has a strength capable of withstanding a shock such as a collision and is as inexpensive as possible, It is preferable to select a resin such as PP-GF resin. Further, as another example, for a door such as a boiler room, for example, a resin such as ABS resin having excellent appearance is selected on the front surface side, and the back surface side is heat resistant, oil resistant, PPS-GF with excellent hot water resistance
It is preferable to select a resin such as a resin and further to select a resin such as a POM resin having excellent abrasion resistance and heat resistance for the upper and lower end surfaces thereof.

Secondly, in the present invention, m kinds of thermoplastic resins (where m is an integer of 2 or more) are extruded in a cylindrical shape from a die head to form a multi-layer parison, and the extruded multi-layer parison is formed. Is divided into multiple parts and guided into an open mold that can receive the parison, and when this mold is clamped for blow molding, the parison has a section width of a specified angle in the circumferential direction and the parison length Direction, and the number of layers of each of these partition regions is n (provided that n is an integer of 1 or more. The number of layers in one or more partitioned areas is two or more)
And the number of layers in each partitioned region is n ₁ for the first partition, n _{2 for} the second partition, ..., N _{p for} the p partition, and the maximum number of layers in it. In the k-th partition n _k
When the number of layers (1 ≦ k ≦ p) is set, the flow paths of the molten resin corresponding to the maximum number of layers n _k are formed in the die head, and the partition regions other than the k-th partition have the partition regions. The maximum number of layers n _k by flowing any of the resins to be formed into a plurality of flow paths
Is characterized in that the molten resin is made to flow over the entire number of channels corresponding to the above, to form a multi-layer parison whose wall thickness is substantially uniform irrespective of the difference in the number of layers n in each partitioned region. It is a multilayer blow molding method.

In the multi-layer blow molding method, according to the experiments by the present inventors, for example, two compartments having a compartment width of 180 ° and being equal to each other as disclosed in Japanese Utility Model Laid-Open No. 3-57,020. A multi-layered partition region having a region (number of partitions p = 2), one of the partitioned regions being a plurality of resin layers, and the other partitioned region being a single-layer partitioned region made of a single resin layer In the case of forming a certain multi-layer parison and performing multi-layer blow molding, generally, the resin flow rate of the molten resin flowing in the multi-layer division area side becomes larger than the resin flow rate of the molten resin flowing in the single-layer division area side. It is easy for the multilayer parison formed by shrinking to the side where the resin flow rate is small to become wrinkled and curved, making it impossible to mold, but in such a case, even in the single-layer partitioned region As many as The same molten resin is flowed through the passage so that it is apparently a single layer, but actually it is a multiple layer made of the same resin, and the overall thickness of the formed multilayer parison is made substantially uniform. The balance of the resin flow rate of the molten resin flowing between the partitioned area and the apparently single-layer partitioned area can be maintained, and thus the above situation can be prevented in advance.

According to the experiments conducted by the present inventors, the total flow rate of the molten resin flowing to the multi-layer compartment area side is apparently 0.7 to 1.3 times the flow rate of the molten resin flowing to the single-layer compartment area side. The range is preferably 0.8 to 1.2 times by weight, more preferably 0.9 to 1.1 times by weight. By adjusting the resin flow rate of the molten resin in this way, In the formed multi-layer parison, the entire wall thickness can be made substantially uniform irrespective of the difference in the number n of layers in each partitioned region.

In the multi-layer blow molding apparatus for carrying out the second method, a plurality of thermoplastic resins are extruded in a cylindrical shape from the die head, and the entire thickness of the multi-layer parison is substantially uniform. Is formed, and the extruded multi-layer parison is divided into a plurality of parts and guided into a parison-acceptable open mold, and the mold is clamped to perform blow molding. The number of resin species used at this time is m (however, 8 ≧ m ≧ 2 is an integer),
The number of layers of the extruded multi-layer parison is n (provided that n is an integer of 1 or more, and the number of layers of any one or more partition regions is 2 or more), and the resin for the multi-layer parison is For any one or more of the seed, the number of layers, and the layer thickness, the number of partitioned regions formed along the parison circumferential direction is p (however,
p ≧ 2), the die head is constructed by assembling cylindrical flow path forming cylinders of a number corresponding to the number of layers n into a multi-cylinder shape and incorporating them into the outer shell flow path forming cylinder. An outer wall surface of each of the flow path forming cylinders, and a multi-cylindrical flow path forming section and a nozzle section that is attached to the lower end of the multi-cylindrical flow path forming section and discharges a multi-layer parison. Corresponds to the number p of sections of each resin layer formed, and
Grooves forming a flow path for the molten resin are formed together with the inner wall surface of the flow path forming cylinder adjacent to the outside thereof, and at least the tips of the extruders corresponding to the number m of the resin species. It can be configured as a device in which the portion and the upper end of each flow path formed in the multiple cylindrical flow path forming part are connected by a resin distribution pipe.

In this multi-layer blow molding apparatus, the number of extruders is the same as the number m of resin species, and at least one branch passage and at least one joint passage are provided in the resin distribution pipe and A flow path switching valve may be provided in either or both of the branch path and the combined flow path. In this way, a branch passage and a joint passage are provided in the resin distribution pipe, and the molten resin supplied from the tip of the extrusion device to the multiple cylindrical flow passage forming portion is controlled by flowing through the resin distribution pipe from the passage switching valve. Thus, the number m of resin species, the number n of layers, and the number p of partitions of the multi-layer parison to be formed can be changed without changing the parts in the die head or the parts relating to the resin flow path, and various hollow molded products can be obtained. It is possible to prepare a multi-layer parison having various patterns required for.

Therefore, according to the second method and apparatus for the second multilayer blow molding as described above, as in the case of the first method and apparatus, a plurality of thermoplastic synthetic resins individually heated and melted are die heads. The multi-layer parison having various patterns of the resin species number m, the layer number n, and the parison circumferential direction partition number p is extruded through the slit of the nozzle located at the tip of the die head. A hollow molded product from a parison has a plurality of partitioned regions of different resin types, and various multilayer blows in which the resin forming each of these partitioned regions exhibits physical properties according to the role of each region in the hollow molded product. A molded product can be produced.

Particularly preferable items which can be blow-molded by the second method and apparatus are chairs and various tables in which a seat portion and / or a back portion is made of a hollow molded article made of a thermoplastic resin. Specifically, when the number of resin layers forming the front surface side is n _f and the number of resin layers forming the back surface side is n _b , n _f ≠ n _b and the outermost exposed The resin layer is divided into two regions forming a front surface side and a back surface side, and each of these divided regions is formed of a plurality of different resins, and preferably a resin layer forming the front surface side. A chair or table made of a thermoplastic resin in which the number n _f is 3 and the number n _{b of} resin layers constituting the back surface side is apparently 1.

Regarding the chair, in the seat portion and / or the backrest portion, the outermost resin layer of the three resin layers on the front surface side, which is exposed on the outer surface and is in direct contact with the human body, has a bending elastic modulus of 5, 5. Made of a soft resin having a hardness of 000 kgf / cm ² or less and a Shore A hardness of 80 or less, the intermediate resin layer is made of an adhesive resin, and the inner resin layer has a bending elastic modulus of 1
50,000 kgf / cm ² or more and Rockwell hardness 6
It is preferable that the resin layer is formed of 0 or more hard resin, and that the resin layer forming the back surface side is formed of the same hard resin as the resin forming the inner resin layer on the front surface side. In addition, regarding the table, the outermost resin layer exposed on the outer surface of the three resin layers on the front surface side is formed of an ABS resin, the intermediate resin layer is formed of an adhesive resin, and the inner resin layer is formed. It is preferable that the resin layer is formed of an olefin elastomer resin, and the resin layer forming the back surface side is formed of a resin of the same system as the resin forming the inner layer on the front surface side. As a particularly preferable chair or table made of a thermoplastic resin molded in this way, for example, a chair provided for a train, an airplane, a theater or the like having a retractable simple table stored on the back of the backrest part. It is illustrated.

Thirdly, according to the present invention, a plurality of thermoplastic resins are extruded in a cylindrical shape from a die head to form a multi-layer parison having a substantially uniform thickness as a whole. The multi-layer parison is divided into multiple parts and introduced into an open mold that can receive the parison, and when this mold is clamped and blow molding is performed, the resin for the multi-layer parison is measured along the circumferential direction of the parison. This is a multi-layer blow molding method in which divided regions that are different from each other in any one or more of the kind, the number of layers, and the layer thicknesses are formed, and the thickness ratio of the resin layer in each divided region is changed along the parison discharge direction. .

In such a multi-layer blow molding method, the multi-layer parison has two partition regions and at least two resin layers of at least the outermost layer and the innermost layer whose thickness ratio changes in the parison discharge direction. The wall thickness ratio between the innermost layer and the outermost layer of one of the partitioned areas in the cross section at any position in the longitudinal direction of the multilayer parison is r _1, and the thickness of the innermost layer and the outermost layer of the other partitioned area is Assuming that the thickness ratio is r ₂ , the product of the wall thickness ratios r ₁ and r ₂ should be approximately 1 so that r ₁ and r ₂
It is advisable to eject the multi-layer parison while changing the respective values.

Regarding the multilayer blow molding apparatus for carrying out the third method, in the multilayer blow molding apparatus for carrying out the second method, the partition width 180 is provided in the multiple cylindrical flow path forming portion. And a multi-channel section for forming two multi-channel sections (having a number of sections p = 2) having an angle of 0 and forming a multi-cylindrical channel for the multi-cylindrical channel forming section. Is divided into a resin merging part for merging a plurality of resins flowing down, and the flow of the molten resin is located below each flow path of the multi-flow path part between the multi-flow path part and the resin merging part. A ring-shaped flow passage that is reciprocable in a direction orthogonal to the direction and that changes the lower end opening width of each flow passage to change the wall thickness ratio of the resin layer in each partitioned region along the parison discharge direction. Consists of a width control valve .

Therefore, according to the multi-layer blow molding apparatus thus constructed, a plurality of thermoplastic resins are extruded in a cylindrical shape from the die head to form a multi-layer parison having a substantially uniform overall thickness. , A hollow molded product formed by blow molding of this multi-layer parison, and the hollow molded product is different from one another in any one or more of its resin type, the number of layers and the layer thickness along the peripheral wall of the cross section of the molded product. While having a partitioned area, the wall thickness ratio of the resin layer in each partitioned area changes along the vertical section wall of the molded product, and the change in the wall thickness ratio along each partitioned area and the vertical section wall of the molded article is hollow. It is possible to manufacture a multi-layer blow-molded product corresponding to each region that the molded product should have and the role of changing the wall thickness ratio.

Therefore, according to the third method and apparatus for multi-layer blow molding, as in the case of the first method and apparatus, the number m of resin species, the number of layers n, and the number of sections in the parison circumferential direction are set. By extruding a multi-layer parison having various patterns of 2 and producing various multi-layer blow-molded articles from this multi-layer parison, by operating the flow path width control valve arranged in the die head, It becomes possible to change the wall thickness ratio between the innermost layer and the outermost layer along the longitudinal direction of the parison for each partitioned area, and to produce a blow-molded product having a pattern of a remarkable change in physical properties in a part of the hollow molded product. You can Moreover, since the wall thickness ratio can be changed along the longitudinal direction of the parison in this manner, a plurality of cavities are arranged in the mold in the vertical direction.
When blow molding multiple hollow parisons from one multi-layer parison at the same time, the cavities can be arranged alternately symmetrically, which allows the molds to be clamped and blow molded. At that time, the mold clamping force can be uniformly applied to the entire mold, and the workability of blow molding is significantly improved.

The multilayer of the present invention will be described below with reference to the accompanying drawings.
Blow molding method and its equipment and obtained by this method
The hollow molded product will be specifically described. First of the invention
Multi-layer blow molding method, its apparatus and this method
The present invention relates to the obtained hollow molded article, and
Multi-layer parison P₁Figure 1 shows the cross-sectional shape of
It is shown intentionally. This multi-layer parison P₁A large number
Kind of resin R₁, R₂, ……, R_mUse the parison
Multiple resin layers L in the thickness direction ₁, L₂, ……, L_nMake up
In addition, the parison has a plurality of divided areas S in the circumferential direction. ₁,
S₂, ……, S_pAre partitioned so that
m species n layers p compartments (where m is the number of resin species, n is the number of layers,
p: number of partitioned areas in the parison circumferential direction)
ing.

In FIG. 1, the cross section is divided into p sections, and the maximum number of layers in each section is n layers,
The maximum number m of resin species is combined within the range of n or less. In FIG. 1, the multilayer parison P ₁ has a uniform thickness over the entire circumference in the circumferential direction of the cross section, but if necessary, one or more of the divided regions S ₁ , S ₂ , ......,
May change the thickness thereof in the S _p, also the partitioned regions S _1, S _2, ......, the resin layer L ₁ in S _p, L _2, ......, by changing the number n of L _n However, the resin layer L ₁ that draws a concentric circle over the entire circumference of the parison in the circumferential direction,
L ₂ , ..., L _n are formed, and each resin layer L ₁ , L ₂ ,.
..., the required number of partitioned areas S ₁ , S ₂ , ... in L _n
..., S _p may be formed.

Then, in this way, in the circumferential direction of the parison
A partitioned area S formed along₁, S ₂, ……, S_pAll of
Any one resin layer L₁, L₂, ……, L_nsmell
At least 45 ° in the circumferential direction of the parison.
Different types of resin that have a width and extend in the parison longitudinal direction
It must be a partitioned area, which allows the Paris
There is one that is used for blow molding by tightening the mold with a mold.
The partition area of the whole goes out of the mold cavity,
The parison part of the compartment is exactly what part of the blow molded product
Will no longer be composed of
There are advantages.

FIG. 2 is a sectional explanatory view of a multi-layer blow molding apparatus used for carrying out the first multi-layer blow molding method, and FIG. 3 shows a flow of molten resin in this molding apparatus. An explanatory diagram is shown in which the is extracted. In this molding apparatus, the die head H basically feeds five kinds of molten resins A, B, C, D and E extruded from five extruders (not shown) to the resin introduction path 1.
The multi-torus portion 1 that develops into the concentric annular flow path 1a via b and a flow for forming partitioned regions of different resin species along the parison circumferential direction for each resin layer forming the multi-layer parison. The molten roots A, B, C, which connect the lotus root portion 2 which constitutes the path 2a and the multi-torus portion 1 and the lotus root portion 2, and which are developed in the five-fold concentric annular flow passage 1a by the multi-trace portion 1. D and E
The octopus part 3 forming a flow path 3a for guiding and guiding the pattern flow paths 2a of the m type n tank p partition divided by the lotus root part 2 according to the resin type, and below the lotus root part 2. The molten resins A, B, C, D and E, which are located and pass through the pattern flow path 2a of the m type n tank p section of the lotus root part 2 and merged thereunder, are discharged as a cylindrical multi-layer parison P ₁ . It is composed of a nozzle portion 4 having a slit 4a.

The above-mentioned lotus root unit 2 is shown by IV in FIG.
-IV line sectional view and VV line sectional view of FIG. 4 and FIG.
(On the contrary, the cross-section of the lotus root portion in FIG. 2 is a cross-sectional view taken along the line II-II in FIGS. 4 and 5).
A plurality of arc-shaped and slit-shaped channels 2 through which the molten resin flows
There are two types of bridge portions 2b and 2c that have a and connect the ends of the flow paths 2a located on the same circumference among them, depending on their roles. That is, the bridge portion 2b has a plurality of arc-shaped and slit-shaped flow paths 2a.
It is provided for the purpose of simply mechanically connecting the respective parts so that the lotus root part 2 forming the parts does not become disjointed. In FIG. 2, the parts are formed in the flow paths 2a of the resins A and E. In order to reduce the traces of the resin flow path division by the bridge portion 2b as much as possible, the width and the length must be as narrow and short as possible.
This bridge portion 2b no longer exists in FIG. 5, which is a sectional view taken along line VV of FIG. Further, the other bridge portion 2c is for essentially preventing the flow of resin, and is provided in the flow paths 2a of the resins B, C and D in FIG. 2, and as shown by the broken line in FIG. The resin is developed in an arc shape so as to surely prevent the resin from flowing, and its length extends to almost the entire length in the vertical direction of the lotus root portion 2 as shown in FIG.

Reference numeral 29 in FIG. 2 is the hydraulic cylinder 3.
The parison controller shaft is driven by 0. By moving the parison controller shaft 29 up and down, the die core 4b of the nozzle part 4 can be moved up and down to adjust the slit 4a of the die discharged by the multi-layer parison. ing. Further, the multi-torus part 1, the lotus root part 2, the octopus part 3 and the nozzle part 4 which compose the die head H are respectively configured as independent parts which can be disassembled and assembled.
The bolt 5a for connecting the multi-torus part 1 and the lotus root part 2 with the sandwiching therebetween and the bolt 5b for connecting the nozzle part 4 to the lotus root part 2 are integrally assembled together.

Therefore, according to this multi-layer blow molding apparatus, various shapes including the lotus root portion 2 and, in some cases, the octopus portion 3 are prepared, and the multi-layer blow molding apparatus having a layer structure of m kinds n layers p sections is prepared. Various hollow moldings are carried out by selecting the lotus root portion 2 and, in some cases, the octopus portion 3 required for forming the layer parison P ₁ and incorporating this into the die head H to form the desired multilayer parison P _1. It is possible to appropriately meet the needs required for the product.

As this multi-layer blow molded product G ₁ , it was attempted to blow mold a door of a boiler room having a structure as shown in FIG. 6 and having high functions such as heat insulation, heat retention and sound insulation. That is, as the resin A, which is the structural base material of the door, glass fiber reinforced polypropylene (PP-GF), which has extremely good blow moldability and relatively high levels of various strengths, and at the same time, is used, Further, as the resin B forming the inner surface of the door which is directly exposed to an atmosphere containing high temperature steam, steam, oil drops, etc., a glass fiber reinforced polyphenylene sulfide (PPS) having excellent heat resistance, hot water resistance, chemical resistance and oil resistance is used. -GF), and further, as the resin C forming the outer surface of the door exposed to the eyes, acrylonitrile-butadiene-styrene copolymer (ABS) having a smooth and beautiful surface and excellent gloss, and ,
As the resin D forming the upper and lower end surfaces of the door that come into contact with the door rail, polyacetal (POM) having excellent abrasion resistance and surface slipperiness is used, and as the resin E located between the two kinds of resins, The multi-layer parison P ₁ was extruded from an extruding device (not shown) through the die head H shown in FIG. 2 using an adhesive resin capable of adhering resins that are difficult to adhere to each other. This extruded multi-layer parison P ₁ has 5 sections (resins A, B, C, D and E) 3 layers (inner layer, intermediate layer and outer layer) 4 sections (see FIG. 7). In the outer layer, two partition regions of resin D having a partition width of 45 °, partition regions of resin B having a partition width of 135 °, and 1
The resin C has a partition area having a partition width of 35 °.

Next, a multi-layer blow molded article G ₁ (boiler chamber door) was blow-molded on this multi-layer parison P ₁ by using a mold disposed directly below the die head H according to a conventional method. As shown in FIGS. 8 and 9, the mold 6 used at this time is divided into four mold constituents 6a, 6b, 6c corresponding to the four partitioned regions of different resin types, When performing mold molding by clamping these mold structures 6a, 6b, 6c, the mold structures 6a, 6b
The abutting portions 7 of b and 6c cut off the boundary portions 8 of the partitioned areas of different resin species, thereby matching the boundary lines of the partitioned areas of different resin species along the ridge lines of the corners of the molded product. There is.

In the multi-layer blow-molded product G ₁ molded in this manner, the two partitioned areas of the resin D constituting the upper and lower end surfaces of the multi-layer blow-molded product G ₁ are at least ⅛ or more of the entire circumference of the peripheral wall of the molded product. have. In the case of a mold that is divided into only two right and left components such as a normal blow molding mold, the concave portion on the upper end surface side of the peripheral wall of the cross section of the molded product has a mold opening between the left and right mold components. In the case of the die 6 shown in FIGS. 8 and 9, the undercut which hinders the operation is made, but by clamping the die 6 divided into four components as described above, The occurrence of undercut in the opening / closing direction can be eliminated.

Further, FIG. 10 shows that in the multi-layer blow molding apparatus shown in FIG.
M'type n'layer p'section (where m ', n'and p'are all 2 or more) by using the die head H for discharging the multi-layer parison P ₁ of p section And m ≧
m ′, n> n ′, and integers satisfying the conditions of p ≧ p ′), the lotus root portion 2 used when forming the multi-layer parison P ₁ has n layers from the outside of the pattern flow passage 2a. This shows an example in which a removable blind ring 9 for closing the lower end opening of the flow path for the n'layer is prepared, and this blind ring 9 has a shape as shown in FIG. Of course, the shape of the blind ring 9 is not particularly limited to that shown in FIG. 11 and may be any shape as long as it can close the flow path lower end opening for the nn ′ layer from the outside of the pattern flow path 2a. The shape may be circular or arc-shaped. By using the blind ring 9 as described above, the multi-torus part 1, the lotus root part 2 and the octopus part 3 of the die head H are prepared so that the multi-layer parison P ₁ having a large number of layers n can be extruded in advance. In this case, the multi-layer parison P ₁ having a smaller number of layers n can be easily formed, and the multi-layer blow molding device can be configured for multiple purposes.

Further, FIG. 12 shows a modified example of the lotus root portion 2. In this lotus root portion 2, semicircular arc-shaped flow passages are concentrically formed on the left and right sides of the center line O in triplets. As a result, the pattern flow path 2a is formed. By replacing the lotus root portion of FIG. 2 with 5 kinds of molten resin to flow, as shown in FIG. Multi-layer parison P with an equal section width of 180 °)
You can extrude _one . In addition, using this lotus root part 2, three resin layers are formed in one of the divided areas,
Further, an apparently single resin layer made of any one of these three kinds of resin is formed in the other partitioned area, so-called half on one side is a multi-layer and the other half is an apparently single layer. Such a multi-layer parison can be easily formed, and at this time, the same resin is flowed through all of the three flow paths 2a that apparently form the partition region on the single-layer side to reduce the thickness of the entire multi-layer parison. It can also be uniform.

As shown in FIG. 3, the flow path 3a of the octopus part 3 is arranged so that the arrangement of the concentric annular flow paths 1a in the multi-torus part 1 matches the layer structure in the lotus root part 2 from the inside to the outside. However, the molten resin C flowing in the outermost flow passage 1a in the multi-torus portion 1 is guided to the innermost flow passage 3a in the lotus root portion 2, for example. You may connect through the octopus part 3. Further, regarding the octopus portion 3 as well, in FIG. 3, all of the five types of resins introduced into the multi-torus portion 1 are connected to the pattern flow path 2a of the lotus root portion 2, but the invention is not limited to this. The octopus portion 3 is of another type, for example, some of the flow passages 1a of the multi-torus portion 1 are closed, and only the remaining flow passages 1a are connected to the pattern flow passages 2a of the lotus root portion 2. It is also possible to prepare one having the flow path 3a and distribute the molten resin of a small amount of the resin species m into several partitioned areas S ₁ , S ₂ , ..., S _p .

Next, FIGS. 14 to 17 show a bumper G ₂ for automobiles, which is a multi-layer blow-molded article having various cross-sectional shapes molded by using the above-mentioned multi-layer blow molding apparatus. The automobile bumper G ₂ shown in FIG. 14 serves as a bumper structural member, forms a hollow rib so as to absorb a shock at the time of a collision, and has a beam portion 10 exhibiting excellent strength and rigidity, and the beam portion 10 of the beam portion 10. The beam portion 10 is laminated on the entire front surface and constitutes the outer surface of the front surface and is directly exposed to the human eye. In this embodiment, the beam portion 10 is formed of PP-GF resin, and the fascia portion is also formed. 11 is made of ABS resin.

The automobile bumper G ₂ shown in FIG.
An adhesive resin layer 12 is interposed between the beam portion 10 of the bumper structural member and the fascia portion 11 that constitutes the outer surface of the front surface of the bumper structural member.
It is a multi-layer blow-molded product using a multi-layer parison of two layers, and the adhesion between the beam part 10 and the fascia part 11 is made stronger. Furthermore. An automobile bumper G ₂ shown in FIG. 16 has a resin layer 13 made of a recycled resin formed inside the beam portion 10 of a bumper structural member so that the recycled resin can be effectively reused. Furthermore, the automobile bumper G ₂ shown in FIG. 17 is obtained by interposing an adhesive resin layer 12 on the structure shown in FIG. 16, and is subjected to multi-layer blow molding using a so-called four-layer, four-layer, two-section multi-layer parison. be able to.

The automotive blower G ₂ thus multi-layer blow-molded can significantly reduce the production cost, and since the whole is integrally multi-layer blow-molded, it is necessary to use an expensive resin that is visible to the eyes. There is a facia part 1
Since the thickness of No. 1 can be made as thin as possible and the amount of the expensive resin used can be greatly reduced, the product cost can be significantly reduced. Moreover, it becomes possible to use the recycled resin in a portion such as the inside of the beam portion 10 which is not exposed to the human eye, and an extremely excellent effect is industrially exhibited.

Next, the present invention relates to a second multilayer blow molding method, an apparatus therefor, and a hollow molded article obtained by this method. A multilayer blow molding apparatus for carrying out this second method is, as shown in FIGS. 18 and 19,
Basically, the number of resin species used at the time of extrusion of the multilayer parison P ₂ is m (however, an integer of m ≧ 2), and the number of layers of the extruded multilayer parison P ₂ is n (however, n is It is an integer of 1 or more, and the number of layers in any one or more of the partitioned regions is 2 or more), and regarding any one or more of the resin type, the number of layers, and the layer thickness of the multi-layer parison P _{2 with} respect to each other. When the number of partitioned areas formed so as to have different partitioned areas along the parison circumferential direction is p (provided that p ≧ 2 is an integer), the die head H has a layer number n (n = 3 in this case). Corresponding to the number of cylindrical flow path forming cylinders 20a, 20b,
20c is assembled into a multi-cylinder shape and assembled in an outer shell flow path forming cylinder 20d, and a multi-cylindrical flow path forming part 20 is attached to the lower end of the multi-cylindrical flow path forming part 20. Nozzle portion 21 for discharging the multi-layer parison P ₂
And the flow path forming cylinder 20.
The number of partitions p of each resin layer formed on the outer wall surfaces of a, 20b, and 20c (in the case of the second embodiment, p = 2 and the partition width is 180).
Flow path forming cylinders 20b and 20c and an outer shell flow path forming cylinder 20d that are adjacent to the outside thereof.
The molten resin channels 22a, 22b, 2
2c is formed, and at least the number of the tips of the extruding device (not shown) corresponding to the number m of the resin species and the flow paths 22a formed in the multiple cylindrical flow path forming section 20 are formed. , 22b, 22c and the upper end of the resin distribution pipe 2
It is configured to be connected by 4a, 24b, 24c, 24d, 24e, and 24f, and when this is expressed by a flow path of molten resin, it is as shown in FIG.

In this Example 2, the number of layers is 3 and the number of sections is 2, and a maximum of 6 types of resins A, B, C, D,
E and F can be supplied, and partition regions having a partition width of 180 ° of the same size can be formed. Then, each resin distribution pipe 24a, 24b, 24c, 24d, 24 connected to the tip of the extruder.
As shown in FIGS. 21 and 22, each of e and 24f is provided with one branch passage 25 and one joint passage 26, and both of the branch passage 25 and the joint passage 26 are provided. Each is provided with a flow path switching valve 27. And
Each resin distribution pipe 24a, 24b, 24c, 24d, 24
From the flow passage switching valve 27 provided in the branch passage 25 and the joint flow passage 26 of e and 24f, for example, as shown in FIG. 21, multiple cylindrical flow from the tip of the extruder through the resin distribution pipes 24c and 24d. The molten resin supplied to the two flow passages 22b of the passage forming portion 20 can be controlled.

That is, FIG. 22 shows a state in which two kinds of resins C and D are switched by the flow path switching valve 27 and supplied to the flow paths 22b on the opposite sides, respectively, and FIG. Is supplied with the resin C only from one of the resin distribution pipes 24c, is distributed to the left and right in the branch passage 25, and is entirely distributed to the two passages 22b through the joint passage 26.
Is being supplied. Therefore, the resin distribution pipes 24a, 2 having the branch passage 25 and the joint passage 26 are formed.
By adopting 4b, 24c, 24d, 24e, 24f, in the flow passage 22b formed by one flow passage forming cylinder 20b, by operating the flow passage switching valve 27, (C,
It is possible to combine four kinds of resins of D), (D, C), (C, C) and (D, D). Since the same thing can be done in all the flow paths 22a, 22b and 22c, the pattern of the layer structure of the multi-layer parison P ₂ which can be formed without using all 6 kinds of resin is enormous. Rise to numbers. Therefore, first, the number and types of resins to be used are determined according to the required physical properties, and then the most suitable one is selected from the layer structure patterns of the multi-layer parison P ₂ that can be formed. By setting each flow path switching valve 27 based on the above, it is possible to obtain a hollow molded product having desired specifications. Then, at this time, it is not necessary to replace the components in the die head H.

In FIG. 18, reference numeral 28 indicates three
Outer shell flow path formation for the flow path forming cylinders 20a, 20b, 20c
A bolt that is used when it is assembled and fixed in the cylinder 20d for use.
And 29 is a hydraulic cylinder 30
This is a parison controller shaft that is driven by
Move the parison controller shaft 29 of
To move the die core 21a of the nozzle portion 21 up and down.
So that the gap between the dies discharged by the multi-layer parison can be adjusted
It has become. Obtained with the method and apparatus of this Example 2
Multi-layer parison P₂Are, for example, 6 types (R ₁~ R₆, Resin A
~ F) 3 layers (L₁~ L₃) 2 sections (S₁, S₂) Layer structure
When it is made, the cross-sectional shape as shown in FIG.
Two partitioned areas S₁And S₂, The number of layers n is 1 to
Any number between 3 and can be changed independently
It

Further, according to this method and apparatus, FIG.
As shown in FIG.₁Is a single resin A
It consists of a single-layer partition area on the top and a partition area S₂Is 3
It is a three-layer multi-layer divisional region composed of resins A, B, and C
Multi-layer parison P₂Can be prepared. So
Then, such a multi-layer parison P₂Specifically, FIG.
And the seat G of the chair as shown in FIG.₃And backrest
G_FourSuitable for molding. That is, the seat portion G
₃And backrest G_FourHuman body exposed on the outer surface
Has three resin layers A, B, and C on the surface side that directly contacts
Multi-layered division area S ₂And the resin B in the outer resin layer
It has a soft feel, feels good on the skin, and does not slip easily
Flexural modulus 5,000 kgf / cm²Below and Shore A
Made of soft resin with hardness of 80 or less, eg elastomer
And the flexural modulus of resin A of the inner resin layer
10,000 kgf / cm²Above and Rockwell hardness
Hard resin with excellent strength and rigidity of 60 or more, eg
For example, it is made of polypropylene (PP).
Between the side resin layer B and the inside resin layer A
The resin layer is composed of the adhesive resin C, and the rear surface side is composed.
About the resin layer A that does, it supports the weight of the person
Therefore, it is made of the same hard resin as above, for example PP.
It

Here, according to the experiments by the present inventors, FIG.
In the multi-layer parison P ₂ as shown in FIG. 5, the total flow rate of the molten resin flowing to the multi-layer partition area S ₂ side is apparently 0.7 to 1.3 of the flow rate of the molten resin flowing to the single-layer partition area S ₁ side.
The weight may be adjusted to a range of times, preferably 0.8 to 1.2 times by weight, more preferably 0.9 to 1.1 times by weight. For example, as shown in FIG. 26, if the resin A on the single-layer divided region S ₁ side is allowed to flow through only one channel to form a literal (true) single layer, the flow rate of the molten resin is balanced as described above. When out of the range, the multi-layer parison P ₂ extruded from the nozzle portion 21 of the die head H shrinks and wrinkles in the direction in which the resin flow rate is smaller (in this case, the single-layer partitioned region S ₁ side), as shown in FIG. This may cause wrinkles and curl, which makes molding impossible. Then, in this way, by controlling the total flow rate of the molten resin flowing to the multi-layer partitioned area S ₂ side and the apparent flow rate of the molten resin flowing to the single-layer partitioned area S ₁ side, in the multi-layer parison formed, It is possible to make the entire thickness substantially uniform regardless of the difference in the number of layers n in each divided region.

[0058]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The multilayer blow molding method of the present invention, the apparatus therefor, and the hollow molded article obtained by this method will be specifically described below with reference to the embodiments shown in the accompanying drawings. This example relates to the multi-layer blow molding method of the present invention, the apparatus therefor, and the hollow molded article obtained by this method. The multi-layer blow molding apparatus for carrying out this method is
As shown in FIGS. 3 and 31, it is basically the same as the multilayer blow molding apparatus for carrying out the second method shown in FIG. 18, and additionally has the following features. That is, in the die head H, the multiple cylindrical flow path forming portion 20
In the same manner as in the second case, two divided areas (the number of divisions p = 2) having a division width of 180 ° and being equal to each other are formed in the multi-cylindrical flow path forming portion 20. Multiple flow channels for forming multiple cylindrical flow channels 22a, 22b, 22c by assembling two cylindrical flow channel forming cylinders 20e, 20f, 20g and an outer shell flow channel forming cylinder 20h into a multi-cylinder shape. It is divided into a portion 20x and a resin joining portion 20y for joining a plurality of resins flowing down the multiple passage portion 20x. The multiple passage portion 20x and the resin joining portion 20y are provided with the above-mentioned multiple passage portion. 20x channels 22a, 22b, 2
Located below 2c, capable of reciprocating in a direction orthogonal to the flow direction of the molten resin, and having the flow paths 22a, 22 described above.
A ring-shaped flow path width control valve 31 that changes the lower end opening widths of b and 22c to change the wall thickness of the resin layer in each partitioned region along the parison discharge direction is interposed.

Incidentally, in these FIG. 30 and FIG. 31,
Reference numerals 21, 28, 29, and 30, respectively, are the same as in the case of the above-described second embodiment, the nozzle portion and the three flow passage forming cylinders 2.
0e, 20f, and 20g are bolts, parison controller shafts, and hydraulic cylinders that are used when assembling and fixing them in the outer shell flow path forming cylinder 20h. In this embodiment, as shown in FIG. 32, the flow passage width control valve 31 has two ring portions 31a and 31c which are concentrically arranged with a predetermined space therebetween and which are connected at two places.
The ring portions 31a and 31c have seat portions 3 formed at the lower ends of the flow path forming cylinders 20f and 20g.
An inclined surface 33 that abuts 2 is provided. The flow passage width control valve 31 is connected to the hydraulic cylinders 34 arranged on both sides in the moving direction, and
As shown in FIG. 4, these hydraulic cylinders 34 are adapted to move to the left and right, and when they are moved to either one, the flow passages 2 of the multiple flow passage portion 20x are respectively returned.
2a and 22c, the lower end opening width in one divided area of one flow passage is narrowed, and at the same time the lower end opening width in the opposite divided area is widened, and the lower end opening width in the former divided area of the other flow passage The width of the lower end is narrowed at the same time as the width of the lower end is narrowed.

That is, in FIG. 33, flow path width control
The valve 31 has one partitioned area S₁To the stroke end
It is shifting by, and at this time the partitioned area S₁Outer layer on the side
35a and the other divided area S₂The thickness of the inner layer 36b on the side is
It is the largest, and the partition area S₁Inner layer 35 on the side
b and the partition area S₂Side outer layer 36a has a minimum layer thickness
ing. Similarly, in FIG. 34, the flow path width control valve 31
Is the other partitioned area S₂Shift to the stroke end on the side
At this time, contrary to the case of FIG. 33,
Partitioned area S₁Side outer layer 35a and the other partitioned area S₂~ side
Of the inner layer 36b of the
Area S₁Side inner layer 35b and the partition area S ₂Outer layer 3 on the side
The layer thickness of 6a is maximum. In addition, these FIG. 33 and
34 and 34, reference numeral 38 denotes the pair of hydraulic cylinders.
Is hydraulic piping for operating the -34, and reference numeral 40 is
With a vector indicating the moving direction and moving width of the flow path width control valve 31
is there.

Therefore, in this embodiment, as shown in FIG. 35, the formed multi-layer parison P ₃ is of 3 types 3 layers 2
Has a layered structure of compartments, and the two compartment areas S ₁ ,
In S ₂ , the outer layers 35a and 36a and the inner layer 35 are
The wall thicknesses of b and 36b are the upper portion 37a and the lower portion 37b along the discharge direction of the parison with the longitudinal central portion as a boundary.
s, and the wall thickness t ₁ of the inner layer 35b and the outer layer 35 of the one partitioned area S ₁ in the transverse cross section at any position in the longitudinal direction of the multi-layer parison P ₃ are changed.
The thickness ratio of the thickness t ₂ of a and r _1, also the thickness ratio of the _'wall thickness t ₂ of the outer layer _36a' thickness t ₁ of the other divided area S ₂ of the inner layer 36b When r ₂ is used, r ₁ and r ₂ are changed so that the product of the wall thickness ratios r ₁ and r ₂ becomes approximately 1.

Therefore, according to the method and apparatus of this embodiment, the number m of resin species and the number n of layers are the same as in the above method and apparatus, and the number p of partitions in the parison circumferential direction is 2. Extruding a multi-layer parison P ₃ having various patterns of
Not only various multi-layer blow molded articles can be produced from this multi-layer parison P ₃ , but also the parison for each of the partitioned areas S ₁ and S ₂ by operating the flow path width control valve 31 arranged in the die head. It becomes possible to change the wall thickness ratio of the innermost layer and the outermost layer along the longitudinal direction, and it is possible to produce a blow-molded article having a pattern of a remarkable change in physical properties in a part of the hollow-molded article. Also,
At this time, since the wall thickness ratio can be changed along the longitudinal direction of the parison, a plurality of cavities are arranged vertically in the mold, and a plurality of hollow molded products are blown from one multi-layer parison at the same time. When molding, the orientations of the cavities can be arranged alternately in a symmetrical positional relationship, so that when the mold is clamped and blow molded, the mold clamping force is evenly distributed over the entire mold. Can be made to act, and the workability of blow molding is significantly improved.

For example, when molding the seat portion and the backrest portion of the chair shown in FIGS. 27 and 28, as shown in FIGS. 36 and 37, the multilayer parison P ₃ pushed out from the nozzle portion 21 of the die head H. The relationship between the two partitioned areas of the wall thickness ratio of the innermost layer and the outermost layer in the cross section of is the opposite in the upper part 37a and the lower part 37b, and the two upper and lower parts formed in the mold 39 are The cavities 39a and 39b are arranged in a symmetrical positional relationship in which the cavities 39a and 39b face in mutually opposite directions, whereby the respective mold halves (M
When the (old half) is clamped and blow molded, the clamping force acts uniformly on the entire mold 39.

[0064]

As described above, according to the present invention, a blow-molded product whose physical properties are partially changed along the circumferential direction of a cross section of a product which has not existed in the past and a layer for each section of the cross section. It is possible to easily produce a product that cannot be molded unless a different number of parisons are formed and a product that cannot be molded unless a parison having a different resin layer thickness ratio in each partitioned region is formed. In that way
It is possible to expand the fields of application of blow-molded products by the product group that is rich in variety of physical property changes. Moreover, it takes very little man and time to change the resin composition of the cross-section of the parison from one pattern to the next, and it is extremely safe and efficient to change the production product. It plays.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a cross section of a multi-layer parison obtained by the first multi-layer blow molding method and apparatus.

FIG. 2 is a cross-sectional explanatory view of a multi-layer blow molding device used for carrying out the first multi-layer blow molding method,

FIG. 3 is an explanatory view showing a flow of molten resin taken out in the molding apparatus of FIG.

4 is a sectional view taken along the line IV-IV and a sectional view taken along the line VV showing the lotus root portion of FIG. 2;

5 is a sectional view taken along the line IV-IV and a sectional view taken along the line VV showing the lotus root portion of FIG. 2;

6 is a cross-sectional explanatory view showing a door of a boiler chamber, which is a multilayer blow-molded product molded by using the apparatus shown in FIG.

7 is a cross-sectional explanatory view showing a cross-section of a multi-layer parison extruded from the device shown in FIG.

FIG. 8 is an explanatory view showing a state in which a multi-layer parison is clamped by a mold divided into four and blow molded,

FIG. 9 is an explanatory view showing a state in which a multi-layer parison is clamped by a mold divided into four and blow molded.

10 is a cross-sectional explanatory view showing the blind ring in a state of being applied to the multilayer blow molding apparatus shown in FIG.

11 is a perspective explanatory view of the blind ring of FIG. 10,

FIG. 12 is an explanatory plan view showing a modified example of a lotus root portion;

13 is a cross-sectional explanatory view showing a multi-layer parison formed by using the lotus root portion of FIG.

FIG. 14 is a cross-sectional explanatory view showing an automobile bumper molded using the first multilayer blow molding device;

FIG. 15 is a cross-sectional explanatory view showing an automobile bumper molded by using the first multilayer blow molding device;

FIG. 16 is a cross-sectional explanatory view showing an automobile bumper molded using the first multi-layer blow molding device,

FIG. 17 is a cross-sectional explanatory view showing a bumper for an automobile molded using the first multilayer blow molding device,

FIG. 18 is a cross-sectional explanatory view of a multi-layer blow molding device used for carrying out a second multi-layer blow molding method,

FIG. 19 is a perspective explanatory view showing the flow path forming cylinder of FIG. 18;

FIG. 20 is an explanatory view showing the flow of molten resin in the molding apparatus of FIG.

FIG. 21 is an explanatory view showing a state where molten resin flows in a resin distribution pipe having a branch passage and a joint passage;

FIG. 22 is an explanatory view showing a state where molten resin flows in a resin distribution pipe having a branch passage and a joint passage;

FIG. 23 is an explanatory view showing a state in which molten resin flows in a resin distribution pipe having a branch passage and a joint passage;

FIG. 24 is a cross-sectional explanatory view showing a multi-layer parison obtained by the second method and apparatus.

FIG. 25 is a cross-sectional explanatory view showing a multi-layer parison obtained by the second method and apparatus.

FIG. 26 is a cross-sectional explanatory view showing a multi-layer parison obtained by the second method and apparatus.

FIG. 27 is a perspective explanatory view showing a seat portion and a backrest portion of a chair formed by using a second multilayer parison;

28 is a cross-sectional explanatory view showing a seat portion or a backrest portion of the chair of FIG. 27,

FIG. 29 is a perspective explanatory view showing a state in which the parison shrinks into a wrinkle when the multi-layer parison is extruded when the resin flow rate is small.

FIG. 30 is a sectional explanatory view showing a multilayer blow molding apparatus for carrying out the method of the present invention,

FIG. 31 is an explanatory view schematically showing the periphery of the ring-shaped flow passage width control valve of FIG. 30;

32 is a perspective explanatory view showing the ring-shaped channel width control valve of FIG. 30,

FIG. 33 is a plan view for explaining an operating state of the ring-shaped flow path width control valve,

FIG. 34 is an explanatory plan view for explaining an operating state of the ring-shaped channel width control valve,

FIG. 35 is an explanatory perspective view showing a multi-layer parison obtained by the method and apparatus of this example.

FIG. 36 is an explanatory view showing a cross section of a multi-layer parison obtained by the method and apparatus of this example,

FIG. 37 is an explanatory cross-sectional view showing how a multi-layer parison obtained by the method and apparatus of this example is clamped with a mold.

FIG. 38 is a partial cross-sectional explanatory view for explaining a multi-layer parison obtained by a conventional method,

FIG. 39 is a partial cross-sectional explanatory view for explaining a multi-layer parison obtained by a conventional method,

FIG. 40 is a partial cross-sectional explanatory view for explaining a multi-layer parison obtained by a conventional method,

FIG. 41 is a partial cross-sectional explanatory view for explaining a multi-layer parison obtained by a conventional method,

[Explanation of symbols]

 1 Multi-torus part 1a Concentric annular flow path 1b Resin introduction path 2 Rotus root part 2a Pattern flow path 2b Bridge part 3 Octopus part 4 Nozzle part 4a Discharge slit 5 Bolt 6 Mold 7 Butt part 8 Border part 9 Blind ring 10 Beam Part 11 Fasher part 12 Adhesive resin layer 13 Resin layer 20 Multiple cylindrical flow path forming part 21 Discharge nozzle part 22 Melt resin flow path 23 Groove part 24 Resin distribution pipe 25 Branch path 26 Combined flow path 27 Flow path switching valve 28 Bolt 29 Parison controller shaft 30 Hydraulic cylinder 31 Flow path width control valve 32 Seat 33 Sloping surface 38 Hydraulic pipe 39 Mold 40 Vector indicating moving direction and moving width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29C 49/78 6122-4F B65D 1/00 B 7445-3E // B29L 22:00 4F (31) Priority claim number Japanese Patent Application No. 4-255157 (32) Priority Date No. 4 (1992) September 25 (33) Country of priority claim Japan (JP) (31) Priority claim number Japanese Patent Application No. 4-255158 (32) ) Priority Hihei 4 (1992) September 25 (33) Priority claiming country Japan (JP) (72) Inventor Satoshi Furuki 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd.

Claims (4)

[Claims] 1. A plurality of thermoplastic resins are extruded in a cylindrical shape from a die head to form a multi-layer parison having a substantially uniform overall thickness, and the extruded multi-layer parison is divided into a plurality of parts. When guiding the parison into an open mold capable of receiving the parison and performing blow molding by clamping this mold, regarding the above-mentioned multi-layer parison, the resin type, the number of layers, and the layer thickness of the multi-layer parison along the circumferential direction of the parison are determined. A multi-layer blow molding method, characterized in that different one or more partitioned areas are formed, and the resin layer thickness ratio in each partitioned area is changed along the parison discharge direction. 2. The multi-layer parison has two partitioned regions and at least two resin layers, at least the outermost layer and the innermost layer, whose thickness ratio changes in the parison discharge direction, and the multi-layer parison is arranged in any of the longitudinal directions of the multi-layer parison. When the thickness ratio of the innermost layer and the outermost layer of the one partitioned area in the cross section at the position is r ₁ and the thickness ratio of the innermost layer and the outermost layer of the other partitioned area is r ₂ ,
The multi-layer blow molding method according to claim 1, wherein the multi-layer parison is discharged while changing r ₁ and r ₂ so that the product of the wall thickness ratios r ₁ and r ₂ becomes approximately 1. 3. The division width 180 is provided in the multiple cylindrical flow path forming portion.
Two partitioned areas having an angle of 0 and being equal to each other (the number of partitions p =
2) is formed, and the multi-cylindrical flow path forming part forms a multi-flow path part that forms the multi-cylindrical flow path and a resin confluence part that joins a plurality of resins flowing down the multi-flow path part. It is divided, between these multi-flow channel portion and the resin merging portion is located below each flow channel of the multi-flow channel portion, and is capable of reciprocating in a direction orthogonal to the flow direction of the molten resin, Further, a ring-shaped flow passage width control valve is provided which changes the lower end opening width of each flow passage to change the wall thickness ratio of the resin layer in each divided region along the parison discharge direction. Multi-layer blow molding equipment. 4. A hollow formed by extruding a plurality of thermoplastic resins from a die head into a cylindrical shape to form a multi-layer parison having a substantially uniform overall thickness, and blow molding the multi-layer parison. This hollow molded product has, in the hollow molded product, partition regions that differ from each other in at least one of the resin type, the number of layers, and the layer thickness along the peripheral wall of the cross section of the molded product, and the resin in each partitioned region The thickness ratio of the layers changes along the vertical wall of the molded product, and the wall thickness change along each of the above-mentioned partitioned regions and the vertical wall of the molded product plays a role in each region and the thickness change that the hollow molded product should have. Multi-layer blow molded product characterized by being compatible.