Method for Welding a Polyolefin Plastic and an Additional Plastic

Abstract

The invention relates to a method for welding a polyolefin plastic and a plastic using a primer, said primer containing at least one maleic anhydride containing polymer and at least one polyester. The invention also relates to correspondingly bonded products.

Claims

1. A method for welding a polyolefin plastic material to a second plastic material, comprising: providing the polyolefin plastic material having a polyolefin surface including a first joining zone; providing the second plastic material having a surface including a second joining zone; providing a primer, wherein the primer comprises a polymer that contains maleic acid anhydride and a polyester polymer; applying the primer to at least one surface to form a primer layer over the joining zone; disposing the first joining zone into contact with the second joining zone wherein the primer is disposed between the joining zones; and welding the polyolefin material to the second plastic material at the joining zones.

2. The welding method according to claim 1, wherein the polyolefin plastic material is selected from polyethene plastic material or polypropylene plastic material.

3. The welding method according to claim 1, wherein: a) the polyolefin plastic material contains a polyethylene and/or polypropylene polymer in an amount of greater than 90 wt. %, in each case based on the total polyolefin plastics material; or b) the polyolefin plastic material has a molar mass (weight average Mw) of greater than 10,000 g/mol; or both a) and b).

4. The welding method according to claim 1, wherein the second plastic material is selected from polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polystyrene acrylonitrile (SAN), polyacrylic ester styrene acrylonitrile (ASA), methyl methacrylate acrylonitrile butadiene styrene (MABS), high impact polystyrene (HIPS), polyamide (PA) or mixtures thereof.

5. The welding method according to claim 1, wherein the primer polymer that contains maleic acid anhydride is a maleic acid anhydride-grafted polyolefin polymer.

6. The welding method according to claim 1, wherein the at least one polymer that contains maleic acid anhydride has a weight-average molecular weight in the range of from 5,000-2,000,000 g/mol.

7. The welding method according to claim 1, wherein the polyester polymer is a copolyester polymer.

8. The welding method according to claim 1, wherein the polyester polymer is derived from at least one acid selected from terephthalic acid and isophthalic acid as an acid component, and at least one alcohol component selected from the group consisting of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropanoate (HPHP), ethylene glycol, diethylene glycol, neopentyl glycol, cyclohexanedimethanol, 1,3-propanediol, 1,4-butanediol and 2-methyl-1,3-propanediol.

9. The welding method according to claim 1, wherein the polyester polyol has a weight-average molecular weight between 1,500 and 100,000 g/mol.

10. The welding method according to claim 1, wherein the polyester polymer is hydroxyl-group-terminated.

11. An object comprising a polyolefin plastic material welded to a second plastic material by the welding method according to claim 1.

12. A polyolefin plastic material welded to a second plastic material selected from the group consisting of polycarbonate (PC), methyl methacrylate acrylonitrile butadiene styrene (MABS), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polystyrene acrylonitrile (SAN), polyacrylic ester styrene acrylonitrile (ASA), polyamide (PA), and high impact polystyrene (HIPS) by the welding method according to claim 1.

Description

EXAMPLE 1

[0131] For a hotplate welding method, a primer was prepared from copolyester 1 and PP-MAH 1 or PP-MAH 2 in a ratio of 50:50 w/w. By means of a hotplate, a melt was produced on a PP and a non-polyolefinic joining part, immersed in a melt of the primer and then joined together. This hot plate welding resulted in the following tensile strengths of the welded samples with a compatibilizing intermediate layer 24 hours after welding.

TABLE-US-00001 TABLE 1 Plastics Plastics Tensile strength material 1 material 2 at RT joining part joining part Compound in N/mm.sup.2 PP PC Copolyester 1/ 2.04 PMMA PP-MAH 1 6.23 PBT 3.83 PET 6.75 ABS 5.19

TABLE-US-00002 TABLE 2 Plastics Plastics Tensile strength material 1 material 2 at RT joining part joining part Compound in N/mm.sup.2 PP PC Copolyester 1/ 4.87 PMMA PP-MAH 2 6.93 PBT 9.68 PET 9.44 ABS 8.00

[0132] As a result, both the very good adhesion of the primer to PP and the non-polyolefinic polymer as well as the excellent weldability of the otherwise incompatible plastics materials could be demonstrated. Without an additional intermediate layer, no significant and measurable results could be achieved.

EXAMPLE 2

[0133] In a further experiment, a primer was prepared from copolyester 1/PP-MAH 2/PP-MAH 3 in a ratio of 50:25:25 w/w/w. In this process, the MAH content was significantly increased by the further PP-MAH. In the hot plate welding method as described above, this primer resulted in 16.89 N/mm.sup.2 for PP-PET.

EXAMPLE 3

[0134] For applications at a higher temperature, semi-crystalline copolyester 2 and copolyester 3 were each used with PP-MAH 2 in a 50:50 w/w mixture.

[0135] The hot plate welding experiments carried out according to the above method demonstrated the following tensile strengths:

TABLE-US-00003 TABLE 3 Tensile strength Plastics Plastics Primer at RT in PP PMMA Copolyester 2/ 11.6 PC PP-MAH 2 4.9 ABS 11.0 PET 16.0 SAN 15.3

TABLE-US-00004 TABLE 4 Tensile strength Plastics Plastics Primer at RT in PP PMMA Copolyester 3/ 7.6 PC PP-MAH 2 15.3 ABS 12.1 PET 13.6 SAN 11.2

[0136] Thus, very high strengths were achieved for the specified material combinations.

EXAMPLE 4

[0137] In order to investigate the adhesion to the non-polyolefinic joining part, the mixing ratio of copolyester to PP-MAH was varied from 50:50 to 60:40 and 70:30 (parts by weight). For this purpose, the primer was prepared accordingly from copolyester 3 and PP-MAH 2, and the materials welded according to the described hotplate welding method demonstrated the following strengths:

TABLE-US-00005 TABLE 5 Strength at Strength at RT at Strength at RT at mixing ratio mixing ratio mixing ratio PP with plastics of 50/50 in of 60/40 in of 70/30 in material N/mm.sup.2 N/mm.sup.2 N/mm.sup.2 PMMA 7.61 8.52 7.54 PC 15.29 15.19 5.66 ABS 12.05 10.53 7.29 PET 13.57 13.47 * SAN 11.24 16.47 * * Since the 70/30 mixing ratio did not show very high strength after welding, this mixing ratio was not tested for PET and SAN.

EXAMPLE 5

[0138] Machine ultrasonic welding was carried out using standard AWS specimens consisting of two T-shaped joining parts. The compatibilizing primer layer consisting of copolyester 1 and PP-MAH 2 in a ratio of 50:50 (parts by weight) was pressed as a film by means of a hot press, cut into strips, placed on the melt after pre-heating one of the T specimens and melted using warm gas. Subsequently, the second T joining part was welded to the coated joining part by means of ultrasound. In addition to the normal tensile strength after 24 hours, the tensile strength after aging was determined, for which purpose the samples were aged in the alternating climate test in 10 cycles per 8 hours between 30 and +60 C. at 98% r.h. 24 hours after welding or after aging, the following tensile strengths were obtained for the various PP-PET material combinations:

TABLE-US-00006 TABLE 6 PP types Tensile strength Tensile strength from various at RT before at RT after manufacturers aging in N/mm.sup.2 aging in N/mm.sup.2 PP 1 7.56 5.42 PP 2 6.68 6.13 PP 3 5.71 7.60

[0139] According to the table, a very high strength was obtained for the welded samples having a compatibilizing primer intermediate layer. In contrast, a reference without a primer layer had no measurable strength.

[0140] In the same method, PP-PC and PP-PA were welded and tested in the tensile test directly or after an alternating climate test:

TABLE-US-00007 TABLE 7 Plastics Plastics Tensile strength Tensile strength material material at RT before at RT after 1 2 aging in N/mm.sup.2 aging in N/mm.sup.2 PP PC 4.88 2.95 PA6 7.35 7.38

[0141] A very high tensile strength was also measured in this experiment.

[0142] The following table shows the tensile strengths before and after aging in the specified methods using other primer layers (in each case 50:50 w/w ratio):

TABLE-US-00008 TABLE 8 Plastics Plastics Tensile strength Tensile strength material material at RT before at RT after 1 2 Primer aging in N/mm.sup.2 aging in N/mm.sup.2 PP PMMA Copolyester 5.99 3.53 2/PP-MAH 2 Copolyester 6.20 3.40 3/PP-MAH 2

[0143] Thus, very high strengths could also be obtained with semi-crystalline copolyester in the primer layer.

EXAMPLE 6

[0144] For infrared welding, plates were used which consisted of the polymers to be joined and were coated at the plate edge of 130*3 mm.sup.2 with the primer. The application method was the same as described for ultrasonic welding. Using a primer consisting of copolyester 1 and PP-MAH 2 (50:50 w/w), the polymer combinations PP-PC, PP-PMMA and PP-ABS exhibited the following tensile strengths after welding, with and without aging:

TABLE-US-00009 TABLE 9 Tensile strength Tensile strengths Plastics material at RT before at RT after combination aging in N/mm.sup.2 aging in N/mm.sup.2 PP/PC 7.44 4.94 PP/ABS 6.36 3.98 PP/PMMA 5.43 2.09

[0145] The results have shown that the primer was also suitable for IR welding. Without a primer, the plastics materials could not be welded. Using copolyester 3 instead of copolyester 1 in the same experiment meant that even strengths of 15.9 N/mm.sup.2 for PP/PC and 10.4 N/mm.sup.2 for PP/ABS could be obtained.