METHOD FOR WELDING A POLYOLEFIN PLASTIC AND A PLASTIC BASED ON A POLYMER CONTAINING CARBONYL GROUPS

Abstract

The invention relates to a method for welding a polyolefin plastic and a plastic based on at least one polymer containing carbonyl groups, using a primer which contains, in relation to the proportion of polymer in said primer, at least 20 wt. % of a polymer that comprises maleic anhydride or maleic anhydride derivative units. The invention also relates to correspondingly welded products.

Claims

1. A method for welding a polyolefin plastics material to a plastics material based on at least one polymer which contains carbonyl groups, using a primer, wherein the primer contains, based on the polymer proportion of said primer, at least 20 wt. % of at least one polymer that comprises maleic acid anhydride units or maleic acid anhydride derivative units.

2. The welding method according to claim 1, characterized in that the polyolefin plastics material is selected from the group of polyethylene plastics material, in particular HD polyethylene, MD polyethylene, LD polyethylene, UHMW polyethylene or LLD polyethylene plastics material, and polypropylene plastics material.

3. The welding method according to claim 1, characterized in that the plastics material based on at least one polymer which contains carbonyl groups is selected from a polyester plastics material, in particular a polyterephthalate ester plastics material, or a polyamide plastics material.

4. The welding method according to claim 1, characterized in that the at least one polymer of the primer is selected from the group of copolymers of at least one maleic acid anhydride monomer and at least one acrylate monomer and/or alpha-olefin monomer and polyolefins grafted with maleic acid anhydride.

5. The welding method according to claim 1, characterized in that the at least one polymer of the primer has a maleic acid anhydride content of between 0.01 and 35 wt. %, in particular between 0.02 and 25 wt. %, preferably between 0.05 and 20 wt. %, particularly preferably between 0.05 and 15 wt. %, based on the polymer.

6. The welding method according to claim 1, characterized in that the at least one polymer of the primer has a weight-average molecular weight Mw in the range of between 5,000 and 2,000,000 g/mol, in particular between 50,000 and 1,000,000 g/mol, preferably between 100,000 and 500,000 g/mol.

7. The welding method according to claim 1, characterized in that the primer contains, in addition to the first polymer, at least one further polymer which is compatible with at least one of the two plastics materials to be welded, preferably at least one polyamide polymer and/or one polyolefin polymer.

8. The welding method according to claim 1, characterized in that the primer contains at least one solvent, in particular water, the primer preferably having a solvent content of between 10 and 95 wt. %, in particular between 50 and 85 wt. %, particularly preferably between 60 and 80 wt. %, based in each case on the total weight of the primer.

9. An object produced using a welding method according to claim 1.

Description

PRACTICAL EXAMPLES

[0088] Used materials and abbreviations:

PA=polyamide
PA 6=polycaprolactam
PA 6.6=poly(N,N-hexamethylene adipic acid diamide)
PA 12=polylauryllactam
PA 6.12=poly(hexamethylene dodecanediamide)
PPA=polyphthalamide
PP=polypropylene
PE=polyethylene
PET=polyethylene terephthalate
PBT=polybutylene terephthalate
MAH=maleic acid anhydride
Primer 1=PP-MAH with MFR (230 C.; 2.16 kg)=7-12
Primer 2=PE-(MD)-MAH with MFR (190 C.; 21.6 kg)=12-22
Primer 3=PE-(LD)-MAH with MFR (190 C.; 21.6 kg)=1.6
Primer 4=PE-(LLD)-MAH with MFR (190 C.; 21.6 kg)=2.5
Primer 5=terpolymer of ethylene, butyl acrylate and maleic acid anhydride
Primer 6=terpolymer of ethylene, ethyl acrylate and maleic acid anhydride
Primer 7=polyolefin; acrylate and MAH modified; Mw=67,500 g/mol
Test fuel composition:

TABLE-US-00001 FAM B in vol. % methanol 15.00 water 0.50 toluene 42.25 isooctane 25.35 diisobutylene 12.68 ethanol 4.23 total 100.00
IR: infrared welding; IR-VIB: infrared/vibration welding; US: ultrasonic welding

Production of the Test Pieces:

[0089] In order to produce the test pieces, the primers, polymers 1 to 4 and the plastics materials to be welded were melted (230 C.) in the plasticizing unit of an injection-molding machine and processed so as to form plates of 130 mm68 mm3 mm.

[0090] The 130 mm3 mm surface of the plates was welded edge to edge to PE, PP, PA and PPA of the same surface area in each case by means of IR welding and vibration welding in order to test compatibility with these materials. Twenty-four hours after welding, 8 mm of the two sides of the welded plate was sawn off, and what remained of the plate was halved (cut perpendicularly to the joining plane) and tested at room temperature using the tensile test at a test speed of 5 mm/s.

[0091] The following table indicates the tensile strength (in MPa) that could be obtained for the welded test pieces for each combination of the primer with the used plastics material and welding method:

TABLE-US-00002 Tensile Welding strength Polymer 1 Polymer 2 Primer method MPa PA6 GF30 PP-MAH VIB 12.6 ULTRAMID B3WG6 PPA PA6T/6I/66 PP-MAH VIB 7.0 GF33 Amodel AE- 1133NT PP Moplen HP501L PP-MAH VIB 20.7 PA6 GF30 PE-(MD)- VIB 7.42 ULTRAMID B3WG6 MAH PA6 GF30 PE-(LD)- VIB 6.31 ULTRAMID B3WG6 MAH PA6 GF30 PE-(LLD)- VIB 5.77 ULTRAMID B3WG6 MAH PE Lupolen GX5038 PE-(MD)- VIB 12.21 MAH PE Lupolen GX5038 PA6 GF30 VIB 0 ULTRAMID B3WG6 PP Moplen HP501L PA6 GF30 VIB <2.5 ULTRAMID B3WG6 PP Moplen HP501L PPA PA6T/6I/66 GF33 Amodel AE- VIB <2.5 1133NT

[0092] The table shows excellent degrees of strength of the primer for PA, PPA and PP. Pure PP and pure PE without a primer only exhibited very low strength for PA and PPA and decomposed after welding without significant amounts of force being applied.

[0093] The primer was injected onto polyamide or PE in a multicomponent injection-molding process. For this purpose, polyamide and PE plates of 150 mm66.2 mm4 mm were first injection molded and inserted into a cavity of 150 mm75 mm4 mm, and the primer polymer was injected onto the PA or PE plastics material in a further injection-molding process. The injected primer layer was machined to a thickness of 1.8 mm. The primer layer was welded to another plastics material and the welded plates were sawn and tested as described above.

[0094] The following table indicates the tensile strength (in MPa) that could be obtained for the welded test pieces for each combination of the primer with the used plastics material and welding method:

TABLE-US-00003 Tensile Primer strength Polymer 1 Polymer 2 Primer on Welding method MPa PE(HD) Lupolen PA6 GF30 PE-(MD)-MAH PA IR 3.66 GX5038BG25 ULTRAMID B3WG6 PE(HD) Lupolen PA6 GF30 PE-(MD)-MAH PA VIB 2.80 GX5038BG25 ULTRAMID B3WG6 PE(HD) Lupolen PA12 GF30 PE-(MD)-MAH PA IR 5.76 GX5038BG25 Grilamid LV-3A H PE(HD) Lupolen PA12 GF30 PE-(MD)-MAH PA VIB 4.47 GX5038BG25 Grilamid LV-3A H PE(HD) Lupolen PA6 GF30 PA IR 0 GX5038BG25 ULTRAMID B3WG6 PE(HD) Lupolen PA6 GF30 PA VIB 0 GX5038BG25 ULTRAMID B3WG6 PE(HD) Lupolen PA12 GF30 PA IR 0 GX5038BG25 Grilamid LV-3A H PE(HD) Lupolen PA12 GF30 PA VIB 0 GX5038BG25 Grilamid LV-3A H PE(HD) Lupolen PPA PA6T/6I/66 IR 0 GX5038BG25 GF33 Amodel AE- 1133NT PE(HD) Lupolen PPA PA6T/6I/66 VIB 0 GX5038BG25 GF33 Amodel AE- 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE-(MD)-MAH PE IR 5.18 GX5038BG25 GF33 Amodel AE- 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE-(MD)-MAH PE VIB 9.17 GX5038BG25 GF33 Amodel AE- 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE-(MD)-MAH PE and IR 8.98 GX5038BG25 GF33 Amodel AE- PPA 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE and VIB 7.80 GX5038BG25 GF33 Amodel AE- PE-(MD)-MAH PPA 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE-(MD)-MAH PPA IR 9.02 GX5038BG25 GF33 Amodel AE- 1133NT PE(HD) Lupolen PPA PA6T/6I/66 PE-(MD)-MAH PPA VIB 8.86 GX5038BG25 GF33 Amodel AE- 1133NT

[0095] The plastics materials welded using the primer layer exhibited excellent strength. Without the primer, the plastics materials decomposed after welding without significant amounts of force being applied.

Aging of the Welded Plastics Materials:

[0096] The following table shows the polymers used and the associated primers. Primer polymer plates and a primer applied to a plastics material in the multicomponent injection-molding process were VIB welded to another plastics material, according to the above-described method. Aging took place at room temperature in test fuel FAM-B and in two different alternating climate tests. The obtained degrees of strength at room temperature and a traction speed of 5 mm/s are given, in MPa, in the following table:

TABLE-US-00004 Primer/on Tensile Polymer 1 Polymer 2 plastics material Welding method Storage strength MPa PA6 GF 30 PE Lupolen VIB 24 h, 20 C. 0.00 Ultramid GX5038 B3WG6 PA6 GF 30 PE Lupolen PE-(MD)-MAH/ VIB 24 h, 20 C. 7.42 Ultramid GX5038 PA6 B3WG6 PA6 GF 30 PE Lupolen PE-(MD)-MAH/ VIB 14 days in FAM-B 6.08 Ultramid GX5038 PA6 B3WG6 PE Lupolen PE-(MD)-MAH VIB 24 h, 20 C. 15.83 GX5038 PE Lupolen PE-(MD)-MAH VIB 80 h (10 cycles) 16.45 GX5038 alternating climate from- 40 C. to 70 C. PPA PE-(MD)-MAH VIB 24 h, 20 C. 9.06 PA6T/6I/66 GF33 Amodel AE- 1133NT PPA PE-(MD)-MAH VIB 80 h (10 cycles) 7.49 PA6T/6I/66 alternating GF33 climate from- Amodel AE- 40 C. to 70 C. 1133NT PPA PE Lupolen PE-(MD)-MAH/ VIB 24 h, 20 C. 9.02 PA6T/6I/66 GX5038 PPA GF33 Amodel AE- 1133NT PPA PE Lupolen PE-(MD)-MAH/ VIB 80 h (10 cycles) 2.37 PA6T/6I/66 GX5038 PPA alternating GF33 climate from- Amodel AE- 40 C. to 70 C. 1133NT PA6 GF 30 PE-(MD)-MAH IR 24 h, 20 C. 8.04 Ultramid B3WG6 PA6 GF 30 PE-(MD)-MAH IR 140 h (35 cycles) 6.62 Ultramid alternating B3WG6 climate from- 30 C. to 80 C. PA6 GF 30 PE-(MD)-MAH IR 14 days in FAM-B 6.08 Ultramid B3WG6 PA12 GF30 PE-(MD)-MAH IR 24 h, 20 C. 9.11 Grilamid LV3AH PA12 GF30 PE-(MD)-MAH IR 140 h (35 cycles) Grilamid alternating 8.13 LV3AH climate from- 30 C. to 80 C.

[0097] The welded plastics materials comprising the primer exhibited excellent resistance to aging in the test media used and under the used test conditions.

Terpolymers as the Primer:

[0098] In another process, primer 5 (terpolymer of ethylene, butyl acrylate and maleic acid anhydride) and, primer 6 (terpolymer of ethylene, ethyl acrylate and maleic acid anhydride) were tested. Primer 5 was pressed in a heating press at 220 C. so as to form a 0.5 mm thick film, melted onto PE by means of a warm gas and IR-VIB welded to PA. Primer 6 was melted at 280 C. and welded to PE and PA by means of hot plate welding.

[0099] The following table indicates the tensile strength (in MPa) that could be obtained for the welded test pieces for each combination of the primer with the used plastics material and welding method:

TABLE-US-00005 Welding Tensile Polymer 1 Polymer 2 Primer method strength MPa PE(HD) Lupolen PA6 GF30 Primer 5 IR-VIB 7.47 GX5038BG25 Durethan PE(HD) Lupolen PA6 GF30 IR-VIB 0 GX5038BG25 Durethan PE(HD) Lupolen PA6 GF30 Primer 6 hot plate 3-4 GX5038BG25 Durethan PE(HD) Lupolen PA6 GF30 hot plate 0 GX5038BG25 Durethan

[0100] The plastics materials welded using the primer layer exhibited excellent strength. Without the primer, the plastics materials decomposed after welding without significant amounts of force being applied.

Hot Plate Welding of PET and PBT Using Polymer Primer 1 and 7:

[0101] At 310 C., PP, PET and PBT were melted on the hot plate on the 30 mm4 mm surface for 20 s, 15 s and 30 s, respectively, the two plastics materials to be joined were dipped into a melt of the primer polymer and the polymers coated with primer were joined at low pressure. For this purpose, primer polymers 1 and 7 were used. After 24 hours at room temperature, the welded samples were tested at room temperature in a tensile test machine at a test speed of 5 mm/s. The polymer combinations and the used primer polymer are shown together with the associated degrees of strength in the following table:

TABLE-US-00006 Tensile strength Polymer 1 Polymer 2 Primer polymer in MPa PP Hostacom PET Genius 72 3.43 M4N01 1 6.44 7 6.33 PP Hostacom PBT GF20 1.19 M4N01 Pocan B3225 1 4.48 7 3.87

[0102] Good degrees of strength of the welded samples could be obtained using the specified primer polymers. Without the primer, the samples welded using a hot plate only had low strength.