MANUFACTURING OF BLOW-MOLDED STRUCTURES FOR TEMPERATURE CONTROL MEDIA

Abstract

A method for producing blow-molded structures where a preform is provided that encloses a cavity and has a preform wall limiting the cavity. The preform is placed into a blow mold and formed to a blow-molded structure, wherein the blow-molded structure has a structural wall. The preform wall or structural wall comprises an inner layer and an outer layer.

Claims

1. A method for producing blow-molded structures, wherein a preform is provided, wherein the preform encloses a cavity and has a preform wall defining the cavity, wherein the preform is introduced into a blow mold and formed to a blow-molded structure, the blow-molded structure having a structural wall, and wherein the preform wall or the structural wall comprises an inner layer and an outer layer.

2. The method according to claim 1, wherein the structural wall is formed from the preform wall, wherein preferably the inner layer of the structural wall is formed from the inner layer of the preform wall and/or the outer layer of the structural wall is formed from the outer layer of the preform wall.

3. The method according to claim 1, wherein the inner layer of the preform wall or the structural wall comprises a polypropylene.

4. The method according to claim 1, wherein the preform wall or structural wall comprises at least 30 to 50 wt. % of a polyolefin.

5. The method according to claim 1, wherein the preform wall or structure wall comprises only two layers.

6. The method according to claim 1, wherein the blow-molded structure or preform has an exterior layer, wherein the exterior layer surrounds the outer layer.

7. The method according to claim 1, wherein the preform is a coextruded tube.

8. The method according to claim 1, wherein the blow-molded structure comprises at least three outlets.

9. A blow-molded structure, wherein the blow-molded structure is produced by the method according to claim 1.

10. Use of a blow-molded structure produced according to claim 1 for guiding a temperature control medium, wherein the temperature control medium comprises water or an oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure is explained in more detail below with reference to three embodiments and three figures.

[0031] FIG. 1 shows a cross-section of a preform according to the present disclosure in a first embodiment,

[0032] FIG. 2 shows a cross-section of a preform according to the present disclosure in a second embodiment, and

[0033] FIG. 3 shows a cross-section of a preform according to the present disclosure in a third embodiment.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a first embodiment of a preform 1 according to the present disclosure in the form of a tube with a constant cross-section. The preform 1 or the tube of the first embodiment comprises a preform wall 2 which encloses a cavity 3. The preform wall 2 is preferably ring-shaped in cross-section and, in particular, circular ring-shaped.

[0035] The preform 1 or the tube or the preform wall 2 of the first embodiment comprises an inner layer 4 and an outer layer 5. Preferably, the outer layer 5 encloses the inner layer 4. In this embodiment, the outer layer 5 is adjacent to the inner layer 4. It is possible that the outer layer 5 is also the outermost layer of the preform wall 2 or the preform 1. In this embodiment, the inner layer 4 is also the innermost layer of the preform wall 2 or the preform 1.

[0036] The inner layer 4 preferably comprises a plastic, more preferably a polyolefin and in particular a polypropylene. The polyolefin of the inner layer 4 is preferably a regenerate.

[0037] The outer layer 5 may comprise a plastic, preferably a thermoplastic elastomer and, more preferably, an olefin-based thermoplastic elastomer and/or an olefin-containing thermoplastic vulcanizate. According to one embodiment, the thermoplastic elastomer of the outer layer 5 is a thermoplastic elastomer of the Santoprene brand or a polypropylene-EPDM mixture.

[0038] According to another variant of the first embodiment, the outer layer 5 comprises polyethylene, in particular HDPE. According to a further variant of the first embodiment, the outer layer 5 comprises polypropylene, in particular impact-modified polypropylene.

[0039] It is highly preferred that the preform 1 is produced by coextrusion. Both the olefin-based thermoplastic elastomer and the olefin-containing thermoplastic vulcanizate comprise an olefin or polyolefin, so that the outer layer 5 adheres well to the inner layer 4. This results in a material-locking, well-adhering composite of the inner layer 4 and the outer layer 5. This is all the more true since, in coextrusion, both plastics are brought into contact with each other in a molten state.

[0040] The preform 1 of the first embodiment is placed in a blow mold after coextrusion and after being cut to size. It is useful to close one end of the preform 1, which can be done in various ways. The preform 1 is then subjected to gas pressure, in particular air pressure, in the cavity 3 of the blow mold not shown here, so that the preform 1 conforms to an inner side of the blow mold and takes on its shape as a blow-molded structure. The blow-molded structure can be, for example, a tank, a tube with a variable cross-section in the axial direction, or a distribution tube. The distribution tube can have a plurality of outlets, for example.

[0041] The blow-molded structure comprises a structural wall which is formed from the preform wall during the blow molding process. The structural wall, which is not shown here for reasons of clarity, comprises in this embodiment an inner layer and an outer layer, the inner layer of the structural wall having been formed in a practical manner from the inner layer of the preform wall 2. Preferably, the outer layer of the structural wall is formed from the outer layer of the preform wall 2. Due to the good adhesion between the inner layer 4 and the outer layer 5 of the preform 1, the adhesive bond between these two layers 4, 5 remained intact during blow molding, thus preventing delamination.

[0042] FIG. 2 shows a second embodiment of a preform 1 according to the present disclosure. It is possible that the preform 1 or the preform wall 2 comprises an exterior layer 6 in addition to the layers 4, 5. The exterior layer 6 can enclose the outer layer 5. It is possible that the exterior layer 6 rests against the outer layer 5. Advantageously, the inner layer 4 is the innermost layer. Preferably, the outer layer 5 is the outermost layer.

[0043] The inner layer 4 of the second embodiment preferably comprises a polyolefin, more preferably a polypropylene and particularly preferably a virgin polypropylene. According to a first variant of the second embodiment, the outer layer 5 preferably comprises a polyolefin, more preferably a polypropylene and particularly preferably a polypropylene regenerate. The outer layer 5 may comprise glass fibers for reinforcement, for example.

[0044] Advantageously, the exterior layer 6 of the second embodiment of the first variant comprises a plastic, more preferably a polyolefin and in particular a polyethylene, preferably an HDPE. Alternatively, the exterior layer 6 may comprise a thermoplastic elastomer and more preferably an olefin-based thermoplastic elastomer and/or an olefin-containing thermoplastic vulcanizate. According to a further alternative, the exterior layer 6 predominantly comprises a polypropylene.

[0045] In a second variant of the second embodiment, the outer layer 5 comprises a bonding agent and the exterior layer 6 comprises a preferably aliphatic polyamide, for example PA11 or PA12.

[0046] The preform 1 of the second embodiment can be subjected to blow molding in the same or a similar manner as the preform 1 from FIG. 1.

[0047] FIG. 3 shows a third embodiment of a preform 1 according to the present disclosure. Compared to the second embodiment, the preform 1 of the third embodiment additionally comprises an adhesive layer 7 and/or an adhesion layer 8.

[0048] It is preferred that the adhesive layer 7 is arranged between the inner layer 4 and the outer layer 5. Advantageously, the adhesive layer 7 adheres to the inner layer 4 and/or to the outer layer 5. The adhesive layer 7 preferably comprises a material which adheres better to the inner layer 4 and/or to the outer layer 5 than the outer layer 5 adheres to the inner layer 4. The adhesive layer 7 preferably comprises a plastic, and in particular a polyolefin. It is particularly preferred that the adhesive layer 7 comprises an adhesion promoter. The adhesion promoter of the adhesive layer 7 can be, for example, maleic anhydride. The proportion of maleic anhydride can be, for example, 3% by weight of the adhesive layer 7. It is preferred that the adhesive layer 7 has a layer thickness which is less than a layer thickness of the inner layer 4, the outer layer 5 and/or the exterior layer 6.

[0049] It is preferred that the adhesion layer 8 is arranged between the outer layer 5 and the exterior layer 6. The adhesion layer 8 advantageously adheres to the outer layer 5 and/or to the exterior layer 6. Preferably, the adhesion layer 8 comprises a material which adheres better to the outer layer 5 and/or to the exterior layer 6 than the outer layer 5 adheres to the exterior layer 6. The adhesion layer 8 preferably comprises a plastic, and in particular a polyolefin. It is particularly preferred that the adhesion layer 8 comprises an adhesion promoter. The adhesion promoter of the adhesion layer 8 can be, for example, maleic anhydride. The proportion of maleic anhydride may, for example, be 3% by weight of the adhesion layer 8. It is preferred that the adhesion layer 8 has a layer thickness which is less than a layer thickness of the inner layer 4, the outer layer 5 and/or the exterior layer 6.

LIST OF REFERENCE SIGNS

[0050] 1 Preform [0051] 2 Preform wall [0052] 3 Cavity of 1 [0053] 4 Inner layer of 1, 2 [0054] 5 Outer layer of 1, 2 [0055] 6 exterior layer of 1, 2 [0056] 7 Adhesive layer of 1, 2 [0057] 8 Adhesion layer of 1, 2