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 consisting of a polymer with at least one aromatic unit in the polymer main chain, using a primer which contains at least one polymer built from at least one monomer with at least one double bond. The invention also relates to correspondingly welded products.

Claims

1. A method for welding a polyolefin plastic and a second plastic containing a polymer with at least one aromatic unit in the polymer main chain, using a primer which contains at least one polymer built from at least one monomer with at least one double bond.

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

3. The welding method according to claim 1, characterized in that the polyolefin plastic contains a polyolefin polymer, in particular a polyethylene and/or polypropylene to an extent of more than 90 wt. %, in each case in relation to the total polyolefin plastic, and/or the polyolefin plastic has molar masses (weight-average Mw) of greater than 10,000 g/mol.

4. The welding method according to claim 1, characterized in that the second plastic is selected from polycarbonate plastics and plastics formed from vinyl aromatic polymers, in particular the second plastic is a polycarbonate plastic formed from a bisphenol, in particular is a polymer containing bisphenol A and/or bisphenol F, or the second plastic is selected from SMMA, SAN, ASA, ABS and AES plastics, in particular is an ABS plastic, or the second plastic is formed from a mixture of a polycarbonate and a vinyl aromatic polymer.

5. 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 which contain maleic acid anhydride groups reacted or polymerized into their chain, in particular maleic acid anhydride-grafted polyolefins, preferably maleic acid anhydride-grafted polypropylene, polyolefin polymers, in particular halogenated polyolefin polymers, preferably chlorinated polyethylene polymers and/or chlorinated polypropylene polymers, preferably chlorinated polypropylene, maleic acid anhydride-grafted, chlorinated polyolefin polymers, in particular maleic acid anhydride-grafted, chlorinated polyethylene polymers and/or maleic acid anhydride-grafted, chlorinated polypropylene polymers, and copolymers which contain, as monomers polymerized therein, at least one (meth)acrylate and at least one monomer selected from a styrene or styrene derivative and at least one further other (meth)acrylate, in particular copolymers containing, preferably synthesized from stearyl acrylate and methyl methacrylate or stearyl acrylate and styrene.

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

7. The welding method according to claim 1, characterized in that the primer, besides the polymer built from at least one monomer with at least one double bond, also contains at least one further polymer, which is compatible with at least one of the two plastics to be welded, preferably at least one polyolefin polymer, such as a PE and/or PP polymer, and/or at least one vinyl aromatic polymer, such as a SMMA, SAN, ASA, ABS and/or AES polymer.

8. The welding method according to claim 1, characterized in that the primer contains at least one solvent, in particular at least one organic solvent, wherein the primer preferably has a solvent content of 10-95 wt. %, in particular 50-90 wt. %, particularly preferably 70-85 wt. %, in each case in relation to the total weight of the primer.

9. The welding method according to claim 8, characterized in that the at least one solvent has a vapor pressure at 20 C. of from 1 to 600 hPa, in particular 2 to 200 hPa, particularly preferably 5 to 20 hPa, and the solvent is preferably selected from the group of tetrahydrofuran, methyl isobutyl ketone, cyclohexanone, and mixtures thereof.

10. An article produced by a welding method according to claim 1.

Description

PRACTICAL EXAMPLES

[0106] Used Materials and Abbreviations:

[0107] PP=polypropylene

[0108] PC=polycarbonate

[0109] ABS=acrylonitrile-butadiene-styrene

[0110] MAH=maleic acid anhydride

[0111] MIBK=methyl isobutyl ketone

[0112] CH=cyclohexanone

[0113] THF=tetrahydrofuran

[0114] PP-MAH=PP-MAH with MFR (230 C.; 2.16 Kg)=7-12

[0115] Chlorinated/modified primer polymers:

[0116] Primer polymer 1=polypropylene; 20.5% chlorine content; MAH modified; Mw=70,000 g/mol

[0117] Primer polymer 2=polypropylene; 22% chlorine content; MAH modified; Mw=60,000 g/mol

[0118] primer polymer 3=polypropylene; 15% chlorine content; MAH modified; Mw=110,000 g/mol

[0119] Primer polymer 4=polypropylene; 32% chlorine content; Mw=100,000 g/mol

[0120] Primer polymer 5=polyolefin; acrylate- and MAH modified; Mw=67,500 g/mol

[0121] IR: infrared welding; IR-VIB: infrared/friction welding; US: ultrasonic welding

[0122] Hot plate welding of PP-PC and PP-ABS with modified polyolefins (primer polymers 1-5:

[0123] At 280 C., PP was melted for 20 s and PC was melted for 40 s or ABS was melted for 20 s over the area of 30 mm4 mm on the hot plate, both plastics to be joined were immersed in a melt of the primer polymer, and the primer-coated polymers were joined under slight pressure. After 24 hours at room temperature, the welded samples were examined in a tensile testing machine with a test speed of 5 mm/s at room temperature. The polymer combinations and the used primer polymer are shown in the following tables with the associated tensile strengths.

TABLE-US-00001 Polymer 1 Polymer 2 Primer polymer Tensile strength in MPa PP PC 5 2.12 Hostacom Makrolon 1 3.34 M4N01 AL2447 2 3.35 3 4.66 ABS 5 5.7 Starex 1 6.99 SD0150 2 6.39 3 7.57

[0124] Good strengths of the welded samples could be obtained with the stated primer polymers. Without primer, the samples welded by heating element had no strength and fell apart from one another directly after the welding.

[0125] Production of Primers 1-3

[0126] In order to produce the primers, the primer components were mixed by mechanical stirring in solvent, dissolved at 90 C., and then degassed at 25 C. The composition of the primers is detailed in the following table in g.

TABLE-US-00002 Primer 1 2 3 Primer polymer 4 35.00 42.00 28.00 ABS-TX-0510T 35.00 28.00 42.00 Disperbyk-168 4.00 4.00 4.00 THF 104.00 104.00 104.00 CH 26.00 26.00 26.00

[0127] The primers were applied at room temperature to the surface (130 mm3 mm) of the PP plastic to be welded. The primer was then dried of the solvent for 24 hours at room temperature. After drying, the thickness of the primer was approximately 0.2 mm. The pre-dried plastic components with a geometry of 130 mm68 mm3 mm were then butt-welded to the 130 mm3 mm surface. The tensile strength was determined at a pulling speed of 5 mm/s at room temperature. Each combination of primer with the used plastics and the welding method and the ascertained tensile strengths (in MPa) is specified in the following table.

TABLE-US-00003 Welding Tensile strength Polymer 1 Polymer 2 Primer Nr. method MPa PP Moplen PC Makrolon 1 IR 7.07 HP501L AL2447 IR/VIB 10.3 PP Moplen PC Makrolon 2 IR 10.19 HP501L AL2447 IR/VIB 9.51 PP Moplen PC Makrolon 3 IR 8.03 HP501L AL2447 IR/VIB 8.42 PP Hostacom PC Makrolon 1 IR 6.32 M4N01 AL2447 IR/VIB 7 PP Hostacom PC Makrolon 2 IR 9.94 M4N01 AL2447 IR/VIB 7.09 PP Hostacom PC Makrolon 3 IR 7.4 M4N01 AL2447 IR/VIB 8.42 PP Moplen PC Makrolon IR 0.2 HP501L AL2447 IR/VIB 0 PP Hostacom PC Makrolon IR 0.84 M4N01 AL2447 IR/VIB 0 PP white, 20% ABS Starex 1 IR 12.04 mineral-filled SD0150 IR/VIB 12.15 PP white, 20% ABS Starex 2 IR 9.94 mineral-filled SD0150 IR/VIB 7.09 PP white, 20% ABS Starex 3 IR 6.62 mineral-filled SD0150 IR/VIB 7.86 PP white, 20% ABS Starex IR 2.63 mineral-filled SD0150 IR/VIB 2.63

[0128] Excellent strengths of the welded PP-PC and PP-ABS plastics were obtained with primer. Without primer, only low or no strength of the welded plastics was obtained.

[0129] Production of the copolymers containing stearyl acrylate and styrene or methyl methacrylate:

[0130] The following table states the used monomer amounts in grams.

TABLE-US-00004 Primer Polymer Stearyl Methyl Dibenzoyl peroxide Nr. acrylate Styrene methacrylate Luperox A75 6 30.2 20.14 0.1045 7 15 35 0.1037 8 16.5 38 0.2078 (in 2 portions) 9 10 40 0.208 (in 2 portions)

[0131] Copolymers of stearyl acrylate, styrene and methyl methacrylate in accordance with the above table were synthesized by radical polymerization. All reactants and the initiator were weighed into a 1 L 2-neck flask and heated in an oil bath under vigorous stirring by means of a magnetic stirrer within 30 min to 95 C. oil bath temperature. After a short period of time, a second portion was added in part to the initiator. Once a solid mass had been produced, the mixture was heated for 5 hours to 150 C. After cooling to 20 C., colorless solids were obtained. The primer polymer nos. 8 and 9 were produced as 20 wt. % solution in THF by stirring in solvent at 20 C. and, as described beforehand, were applied to the area of 130 mm3 mm to PP and welded with PC. Primer polymers 6 and 7 were used as solids for hot plate welding as described above. The joining part combination PP Hostacom M4N01 and PC Makrolon AL2447 was used. The tensile strengths at room temperature and a test speed of 5 mm/s, the used primer polymer, and the welding method are presented in the table below.

TABLE-US-00005 Primer Tensile strength Polymer Nr. Welding method MPa 6 Hot plate welding 2.30 7 Hot plate welding 1.31 8 IR/VIB 5.08 9 IR 4.96

[0132] Good strengths of the welded samples were obtained with primer polymers.

[0133] Amine Pre-Treatment of PC:

[0134] The used amines and concentration thereof in isopropanol are stated in the following table. PC Makrolon AL2447 plates of 130 mm68 mm3 mm were immersed into the amine solution under the conditions (time and temperature) stated in the table and then left to dry off the solvent residue at room temperature for 24 hours. By means of a hand extruder (Alpha 2; Wegener International GmbH), a PP-MAH with a MFR=7-12(230 C.; 2.16 Kg) at 230 C. melt temperature was extruded onto the amine-treated PC plates pre-heated by hot gas at 280 C. for 15 seconds. After 24 hours a qualitative assessment of the adhesion was performed by peeling off the extrudate. The assessment is also included in the table below.

TABLE-US-00006 PC immersion time and Qualitative temperature of adhesion Concentration and amine in isopropanol the solution assessment 3 wt. % 1,12-dodecanediamine 2 sec; 65 C. 2 3 wt. % 1,12-dodecanediannine 10 min; 65 C. 1 10 wt. % 1,12-dodecanediamine 10 min; 65 C. 2 10 wt. % 1,12-dodecanediamine 30 min; 65 C. 1 3 wt. % 1,6-hexamethylendiamine 2 sec; 65 C. 2 3 wt. % 1,6-hexamethylendiamine 10 min; 65 C. 1 10 wt. % 1,6-hexamethylendiamine 2 sec; 65 C. 2 10 wt. % 1,6-hexamethylendiamine 10 min; 65 C. 2 3 wt. % ethanolamine 10 min; 65 C. 3 3 wt. % ethanolamine 30 min; 65 C. 2 10 wt. % ethanolamine 10 min; 65 C. 2 3 wt. % 2-piperazin-1-ylethylamine 2 sec; 20 C. 1 3 wt. % 2-piperazin-1-ylethylamine 2 sec; 65 C. 1 3 wt. % 2-piperazin-1-ylethylamine 10 min; 65 C. 2 3 wt. % 2-piperazin-1-ylethylamine 30 min; 65 C. 2 10 wt. % 2-piperazin-1-ylethylamine 2 sec; 20 C. 2 10 wt. % 2-piperazin-1-ylethylamine 2 sec; 65 C. 1 10 wt. % 2-piperazin-1-ylethylamine 10 min; 65 C. 2 10 wt. % 2-piperazin-1-ylethylamine 30 min; 65 C. 2 Without pre-treatment 3 Isopropanol 2 sec; 20 C. 3 1 = Extrudate cannot be peeled away from the PC, 2 = Extrudate can be peeled away from the PC with medium force applied, 3 = Extrudate separates from the PC without significant force applied.

[0135] Excellent adhesion of the PP-MAH to the PC was attained with many amine pre-treatments. Reference tests without pre-treatment or with pre-treatment with pure isopropanol revealed no adhesion of the extrudate on the PC.