JPH0288214A - Multi-layer blow molded product where constituent number of layers and thickness of layers are different partly from one another - Google Patents

Abstract

PURPOSE:To obtain reasonable molding technique by contriving a cost reduction, by constituting the title molded product so that a constituent number of layers of a part are different from those of the remaining part and a thickness of the layer of the part is different from that of the remaining part. CONSTITUTION:A part 3A of a parison 3 and the remaining part 3B are made respectively into three layer and two layer structure. In other words, a surface layer (outer layer) 30 in the part 3A is omitted and constituted of two layers of an intermediate layer 31 and inner layer 32 in the part 3A. Then, for example, while the surface 4A of a bumper 4 is of the three layer structure, the backside 4B is made into two layer structure of the intermediate layer 41 and inner layer 42. In case of manufacture of a molded product, three units of extruding machines 6A, 6B, 6C are used and at the time of casting of molten resin into respective ring plungers 7A, 7B, 7C only the ring plunger 7A which is close to the extruding machine 6A for an outer layer is made into a semicircular plunger. Since a semicylindrical sleeve 8 is inserted into a semicircular part on its opposite side for filling-up its air gap so that the molten resin does not come into the same, a parison 3 which does not have the outer layer 30 on a half side is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to multilayer blow molded articles, and more particularly.

A multi-layer blow-molded product is made by using various plastic materials, and this is blow-molded to make a multi-layer blow-molded product, but the number of layers is partially different. The present invention also relates to a multilayer blow molded product in which the thicknesses of these parts are different.

[Prior art] A parison is blow-molded to produce a blow-molded product of a desired shape (
Manufacturing of blow molded products has been widely practiced for a long time.

In such a case, in the conventional example, even if the parison is made of +1t- plastic key family, multiple plastic +4
Even if the parison has a multi-layered structure, the entire circumference of these parisons has a uniform thickness (thickness). Therefore, the hollow molded product obtained by blow molding this parison also has a uniform thickness throughout. It is made up of thickness.

Figure 6 C△) shows a cross section of a three-layered parison.
The parison 1 has the same thickness over its entire circumference, and the parison 1 is blow-molded to form the sixth parison 1.
The cross-section of a bumper 2 for an automobile 1, as shown in FIG. 1B, has a uniform thickness throughout.

JP-A No. 62-28472 describes a hollow molded product using partially different plastic materials, but the hollow molded products are only partially different in composition (persimmon type of plastic material). As described in the publication and as shown in the figure (FIG. 4), the hollow molded product has a constant thickness throughout.

Also, in JP-A-61-249736.

In a blow-molded plastic tank made of high-density polyethylene, a contact A/N layer, and a nylon layer, the upper and lower ends are made of a single layer made of only high-density polyethylene,
A multi-layer parison is extruded with a part of the center layer being similarly layered, and then blow molding is performed to form a dual-purpose fuel tank. A molding technique is described that has a layered portion and a layered portion.
The layer is a 0: layer consisting only of high-density polyethylene, and in fact, as shown in Figure 3 of the same publication, the tank has a multilayer part and a JP layer part. However, the thickness in these parts is the same.

Furthermore, Japanese Patent Publication No. 61-171:320 and 58-22
Publication No. 0738 similarly describes a multilayer blow molded product (fuel tank) in which the number of layers is partially different, but these parts are constructed to have the same thickness.

[Problem to be solved by the invention] In this way, if the entire circumference of the parison or the entire cross section of the molded product has a certain number of layers, for example, if there are three layers, two layers will make the whole +^, and the thickness will be uniform throughout. If the number of components in one layer is partially different, but if the thickness of the first layer and the first layer are the same, for example, the automatic In the case of type bumpers, even if the part exposed on the surface is required to have a low modulus and a wide range of paintability, the part hidden on the back side may not have such a need. Making the number of layers constant throughout or making the thickness uniform throughout wastes material costs and increases the cost of the molded product.

Therefore, in view of such prior art, the present invention has been developed, for example, in an automatic 1
In items such as RI's bumpers, the parts that are exposed on the surface are designed to maximize the performance required of the product, but the parts that are hidden behind the surface are made by reducing the number of layers and by reducing the number of layers. By making the thickness thinner, we aim to reduce costs and provide a rational molding technique.

[Means for Solving the Problems] That is, the present invention provides a plastic multilayer blow-molded product in which one multilayer parison is blow-molded into a desired shape, and the number of layers in that part is 5 times the number of layers in the remaining part. ′(A plastic multilayer blow-molded product having partially different number of layers and layer thickness, characterized in that the layer thickness of the −・ portion and the layer thickness of the remaining portion are different. 2) 1- The multilayer blow molded product has a multilayer structure automatically! 1 (
A bumper for use in a vehicle, wherein the portion that appears on the front surface as the bumper has a three-layer structure, while the portion that is hidden on the back surface as the bumper has a layered structure, and
This product relates to the plastic multilayer blow-molded product according to Paragraph 1U (1), in which the thickness of these parts is not uniform and the part hidden on the back surface is thinner than the part exposed on the front surface. be.

[Function] In the present invention, in a parison or a blow-molded product made by blow-molding the parison, as in the past, over the entire circumference of the parison, or in the case of a blow-molded product, over the entire circumference,
Instead of making the number and thickness of layers uniform, the number of HN partial layers was varied and the Jv value was partially varied.

For example, one part is made into three layers, and the remaining part is reduced to two layers, and in this case, the thickness of the remaining part made of two layers is not made the same thickness as the part made of three layers, but is made to have the same thickness of two layers.

As a result, the material cost can be reduced by a large amount.

In addition, for example, in the case of a car bumper, some of the above may be
If it is a part that appears on the surface, the surface layer must have low modulus and be paintable, so a three-layer structure with a surface layer that has low modulus and good paintability is used. There are times when such performance is not particularly required for hidden parts.

In such a case, conventionally, blow molded products with a uniform number of layers and thickness were created in accordance with the above required performance even in areas where this was not necessary, while feeling that there was no need for this on the back side. was offering.

In such a case, the present invention reduces the number of layers in unnecessary portions within a range that does not cause problems with the product, and furthermore, the number of layers is reduced by -4- to the extent of reducing the thickness.

In other words, we tried to create multiple layers with a focus on one area.

As a result, according to the present invention, it has become possible to eliminate the inconveniences in the above case and to advance rational blow molding technology.

[Example] Next, the present invention will be explained based on drawings showing examples.

In addition, in the following examples, examples of molding methods for achieving the above-mentioned object [1] of the present invention will also be explained.

FIG. 1(A) is a cross-sectional view of a parison showing an embodiment of the present invention, in which a part 3A of the parison 3 has a two-layer structure, while the remaining part 3B has a two-layer structure. That is, the surface layer (outer layer) 30 in the part 3Δ is omitted, and the part 3A is composed of two layers, the intermediate layer 31 and the inner layer 32.

FIG. 1 (13) shows a cross-sectional view of the bumper 4 for the automatic 1 after the parison 3 has been blow-molded, and has a blow-molded cross section corresponding to the parison 3, and is displayed on the surface of the bumper 4. The visible part 4△ has a three-layer structure, whereas the hidden part 4)3 is the part 4A that is visible on the front surface, with the surface Ifl (outer layer) 40 omitted and It is composed of two layers, an intermediate layer 41 and an inner layer 42 in 4A.

FIG. 2 shows another embodiment of the invention.

This embodiment is an example of a fascia in which the front and rear bumpers and spoiler of an automobile are integrally molded, and the fascia 5 has a two-layered surface portion 5A and a two-layered back surface as shown in FIG. It is composed of a portion 5B.

Next, a preferred example of the plastic material forming the multilayer blow-molded product (parison) of the present invention will be explained based on the above two-layer structure.

11i green material layer or polyolefin, which is made of a composition containing a crystalline polyolefin and an engineering plastic or a polyolefin-based halo elastomer composition, and the intermediate M41 is made of molding and/or defective molded products in the production of the multilayer blow molded product. Alternatively, it is preferable that the foam layer is made of the +li main material, and the inner layer 42 is made of crystalline polyolefin.

As shown in item L, the outer layer 40 is made of a composition containing crystalline polyolefin and engineering plasti.
The inventors of the present invention have found through extensive studies that the multilayer blow-molded product in which the inner layer 42 is made of crystalline polyolefin does not require an interlayer adhesive (die resin) and has strong interlayer adhesive strength. Separate patent application filed.September 16, 1988. Application 1 Name of invention r Multilayer blow molded product J) That is, in the past, multilayer blow molding of polyolefin and engineering plastic required an adhesive layer between the layers. In addition, due to the difference in the coefficient of linear expansion of each resin layer, there is a gap between the layers after molding. , L, it was possible to eliminate the need for an adhesive between one layer and to have strong interlayer adhesive strength.

In addition, blowing engineering plastic alone or blowing a composition of polyolefin and engineering plastic alone results in insufficient moldability, especially large-sized blow moldability, but this problem has been solved. Further, although conventional polyolefin blow-molded products had problems in paintability, the above-mentioned method made it possible to impart paintability to the outer layer 40.

- On the other hand, multilayer blow-molded products made of a polyolefin thermoplastic elastomer and crystalline polyolefin similarly do not require adhesive between the ribs.

Moreover, it has strong interlayer adhesive strength.

Furthermore, paintability, compression recovery properties, and a soft feel can be imparted to polyolefin blow-molded products. Furthermore, since the polyolefin thermoplastic elastomer composition has greater rigidity than a single blow molded product, large-scale blow moldability can be improved.

Therefore, the outer layer 40 of the blow-molded product described in 1- above can impart paintability and rigidity (low modulus), and the composition layer can maximize the performance required as a bumper.

The foam layer of the intermediate layer 41 provides compression recovery properties, and in the case of an elastomer composition, it can provide the compression recovery properties of the layer.

]-2 Crystalline polyolefins include ethylene or propylene, butene-1, pentene-1, hexene-1
Examples include single polymers of α-olefins such as 1,4-methyl-pentene-1, polymers of ethylene and α-olefins, or copolymers of 2M! or more of these α-olefins. Among polyolefins, low density polyethylene, linear low density polyethylene, medium/high density polyethylene, polypropylene, propylene-ethylene random or block copolymer are preferred.
Among these, high-density polyethylene, polypropylene, and propylene-ethylene block copolymers are particularly preferred.

The above engineering plastics include polyamide (PA, homo, copolymers and mixtures thereof), polyester CPET, PBT and modified products thereof), polycarbonate (PC), modified polyphenylene oxide (modified PPO), polyphenylene sulfide (PPS),
polyarylate, ABS resin, or a mixture thereof (
Example 1) to/PI3T, PBT, pc, modified ppo, pp
S or polyarylate, PC/PET or PBT).

Polyolefin and engineering plastics
The second product is a composition of a polyolefin, the above-mentioned engineering plastics, and a compatibilizer thereof. These compositions desirably contain at least 5% or more of the polyolefin and/or compatibilizer.

Examples of compatibilizers include modified polyolefins obtained by grafting unsaturated carboxylic acids or derivatives thereof onto polyolefins, and low-crystalline ethylene-〇-olefin comonomers (E
P RlE [3R, etc.), 1n combination of ethylene propylene diene (EPr) M styrene-butadiene block combination + lt combination (S B [N) 9-body fsE combination into styrene-propylene block), styrene-ethylene-butylene -Styrene block copolymer (SEI3), rEP
l) Graft copolymers of M and styrene and acrylonitrile (AES), styrene-maleic anhydride co-merged, small styrene-based polymers containing epoxy groups, styrene-based copolymers containing oxazoline rings, etc. Polymers, saponified products of ezalene-vinyl acetate copolymers, oxazoline ring-modified polyolefins, epoxy group-containing polyolefins, and the like can be mentioned.

Examples of desirable compositions include (1) polyolefins (polyethylene to LDP I
E, 1, L D P E , II D P E ,
Polypropylene, propylene-ethylene 7% Q combination ~
Random, by block/Polyamide (nylon 6, nylon 66, nylon 12, nylon 66, nylon 61
0''5)/a polyolefin modified with an unsaturated carboxylic acid or its anhydride.

(2) The above composition/low crystalline ethylene-〇-olefin copolymer (E I) R, E B R, E P D
M, etc.) or an unsaturated carboxylic acid modified product thereof.

(3) Modified mixture of polyolefin and polyamide with unsaturated carboxylic acid or its anhydride/polyamide/
A composition consisting of polyolefin.

The blending ratio of the above composition is 5 to 951 parts of polyolefin or modified polyolefin, 95 to 51 parts of polyamide.
The low-crystalline ethylene-〇-olefin copolymer is preferably in an amount of 5 to 50 weight parts per part f1 of the polyolefin and polyamide.

(4) Polyolefin/polycarbonate (aromatic polycarbonate, etc.)/styrenic copolymer (SBr1.S
EP, SEB, AES, styrene/anhomaleic acid)
Furthermore, EPR, EPDM, oxazoline ring-modified polyolefin, and epoxy group-containing modified polyolefin are calculated.

(5) Polyolefin/polycarbonate/unsaturated carboxylic acid-modified polyolefin/styrenic copolymer/polyester (f) 13'T'', 1) 1mi, 1', etc.) (
6) Polyolefin/polycarbonate/saponified EVA
Specialty can be given.

The blending ratio of the above composition is polyolefin 5-95II
'IIi, polycarbonate 95~S ffi 1
In 2 parts, styrenic co-combined, modified polyolefin, polyester, saponified Ey A J is 2 parts for polyolefin and polycarbonate lOO+Tf jit part.
-100 Sunny part is preferable.

The foam layer is made of the above-mentioned polyolefin, preferably polyethylene, polypropylene, propylene-ethylene co-IR composite, ethylene-propylene rubber, ethylene-propylene-diene co-In composite rubber, ethylene-vinyl acetate copolymer, or a mixture thereof. 11: A multilayer parison is blow molded by adding a foaming agent to the raw material obtained by cutting or pulverizing the parison and/or defective molded product in the blow molding of the present invention described in 1, and extruding and foaming it by melt-mixing. In addition, as a blowing agent, polyolefin or +
Any compound that decomposes or vaporizes at a temperature higher than the melting point of the Ti raw material can be used as long as it does not substantially interfere with multilayer blow molding.The type of blowing agent added is selected as appropriate depending on the use of the blow molded product. However, in general, it is preferable to use about 05 to 15 weights and 11 points per 100 weights of resin.

1. The polyolefin thermoplastic elastomer composition is a composition comprising a polyolefin, an olefin rubber and/or other synthetic rubber, and a mineral oil softener (process oil, etc.). These compositions preferably contain at least 5 to 50% polyolefin, and these compositions may be of a simple blend type of each component, a type in which the rubber component is partially crosslinked, or a type in which the rubber component is completely crosslinked. Any type of cross-linked material may be used.

Next, an example of the molding method of the present invention will be described.

When manufacturing a multilayer blow molded product with three layers using an accumulator head as shown in Figure 3,: 3
Using extruders 6Δ, 613.6C, molten resin is injected into the respective ring plungers 7Δ, 7, 13.7C and extruded to form a parison. A parison 1 is obtained in which the intermediate layer 31 and the inner layer 32 are concentrically solidly bonded, have a uniform thickness over the entire circumference, and have a uniform layer structure (three layers).

However, only the ring plunger 7A adjacent to the outer layer extruder 6Δ is made into a semicircular plunger, and a semicylindrical sleeve 8 is inserted into the semicircular portion on the opposite side to prevent the molten resin from entering. By filling that void,
A parison 3 as shown in FIG. 1(A) can be obtained without the outer layer 30 on the half side.

By blow molding this parison 3, as shown in Fig. 1 (
A bumper 4 as shown in 13) can be obtained.

In FIG. 73, 9 indicates an accumulator, 10 indicates a mandrel (core), and 11 indicates a cylinder.

Molding according to the invention is also possible using an accumulator head as shown in FIG.

That is, in the three-layer accumulator head as shown in FIG. 4, the flow of molten resin from the extruder (not shown) to the accumulator head 12 is uniform and rapid in one circumferential direction. As shown in FIG. 5, it is common to branch into two to feed the molten resin into the accumulator.

In this case, the above-mentioned parison 3 is obtained by opening one side of the flow path 13 of the bifurcated structure and allowing the molten resin to flow only toward the cylindrical plunger side, as schematically shown in FIG. be able to.

Although the invention made by the present inventor has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified without departing from the gist thereof. Nor.

For example, although we have mainly shown examples of multilayer blow molded products with a three-layer structure, a high-density polyethylene layer, an adhesive layer,
The present invention can also be applied to blow-molded products having three layers consisting of a barrier material layer, an adhesive layer, and a high-density polyethylene layer.

In addition to bumpers and facias, the present invention also applies to various r1
It can be applied to various multilayer blow molded products such as moving parts and containers.

[Effects of the Invention] As is clear from the following explanation, according to the present invention, cost reduction and rationalization can be achieved in multilayer blow molding, making it possible to achieve industrially very advantageous blow molding technology. were able to provide.

[Brief Description of the Drawings] Figure 1 (8) is a cross-sectional view of a parison showing an embodiment of the present invention, Figure 1 (B) is a cross-sectional view of an automatic Ichikawa bumper using the same parison, and Figure 2 is a cross-sectional view of an automatic Ichikawa bumper according to the parison. Automatic ijt showing other embodiments
FIG. 3 is an explanatory diagram showing the molding method of the present invention, and FIGS. 4 and 5 are explanatory diagrams showing the molding method of the present invention, respectively. FIG. 6+A) is a cross-sectional view of a conventional parison, and FIG. 6 (13) is a cross-sectional view of an automobile bumper using the same parison.・Parison・Auto heavy duty bumper・Parison・Automobile bumper 6C...Extruder 7C...Ring plunger・Sleeve・Accumulator・Mandrel・Cylinder・Acculator head・Flow path 6 Δ l 2 ・ l : 3 ・ 2 ・:3 ・ 4 ・ 5 ・ 613° 8 ・ 10 ・ 7 Δ Figure 1

Claims (1)

[Scope of Claims] 1. A plastic multilayer blow-molded product obtained by blow-molding a multilayer parison into a desired shape, wherein the number of layers in a part of the part is different from the number of layers in the remaining part, and the thickness of the part of the layer is different from the number of layers in the remaining part. 1. A plastic multilayer blow-molded product having partially different number of layers and layer thickness, characterized in that the layer thickness and the layer thickness of the remaining portion are different. 2. The multilayer blow molded product is an automobile bumper with a multilayer structure, and the part that appears on the surface as the bumper has a three-layer structure, while the part that is hidden on the back side as the bumper has a two-layer structure. 2. The plastic multilayer blow molded product according to claim 1, wherein the thickness of the parts is not uniform, and the part hidden on the back surface is thinner than the part exposed on the front surface.