DE1669930A1 - Process for bonding thermoplastic materials to metals - Google Patents

Description

D1FL.-PHYS. 0R. 3L FlNGKE l ^ ENTÄN ^ KföpE 1BBS330 f MUNICH 27, MOHLSTKASSa22, RUFNUHMEB. 4IM2I / 22

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V er drive for gluing -rom thermoplastic materials

concerns the TTei ^ lefeea of. Kutts ^ ötö £ föa with metal substrates, in particular it relates to an improved surface treatment of metal substrates, which results in improved adhesive strength between plastic material and metal substrate, '|

Various methods for improving the adhesion of plastic over trains on metal substrates have already been proposed. Was used haf tungsverbessernda agents, such as polyalkyleneimines, or monolayers of organic acids for the, coating of metal substrates vor'der up ■ _o Delivering the Kunatatoffmaterials. It has also been

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seeks to improve Md Eunsrfcstoffliatung am Metallsukstrat- BQ ¹ TIiP i & Läem ßem plastic Chromate added or the Eunstatöff ^^ - XSisufofflatBn. Was covered. Bachv etea above & erge & teil2t _; e · SciiicMstaff © goods ^ eiäöcli Mciit

+ & äie -Haf .t £ estig ^ eüi avclscaeji Poly-, merisat ua € iletalX imauxeicJieiia fcelbekaltea wu.rd; e>-Wena; For example Sciiiclitstoifö zixrn protecting objects against one (il1rfee "U2ig ^ i» FLÜS & e v «rweziGte $ werctert _t <^ twäciit a long continuous exposure to lasser or Peucntig- usually ness that Pestigkeit the adhesive bond between

The aim of the invention is therefore to create an improved * th procedure for the connection © the VerJcXebimg von Eunst » substances with treated metal surfaces. I'm another one The aim is to create a process for producing, Position of ScMc ^ tBtoffea ^ fi ^

ability "Mn special Möl is a method for handling ^ ment, from lfetaO € & erf lachen * by vrelches, olefin polymers with which the nimble surfaces are glued in this way.

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The method according to the invention for achieving the above The aim is to have a metal surface on a

substantially salt-free aqueous inorganic acid solution _f containing hexavalent chromium, and / or a solution containing an aliphatically © carboxylic acid, "Switching 'is allowed to act is · The thus obtained treated metal surface has improved adhesive properties of polymeric plastics and allows for the Establishing firm adhesive bonds with these when manufacturing coated objects and laminates. For example, a laminate with high bonding strength is produced between the lamellas by applying a thermoplastic polymer film to a dry, treated metal surface and exposing the bond to heat and pressure.

In one embodiment of the invention, a metal, such as aluminum, is brought at elevated temperatures into a practically salt-free aqueous solution of an inorganic acid which contains hexavalent chromium, for example chromium trioxyc ¹ /. The treated material is washed with water and placed in a second solution containing an aliphatic carboxylic acid such as maleic acid, washed again and then dried. The metal treated in this way is used to form a thermoplastic material such as polyethylene.

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connected by heating the collapsed structure to temperatures between about HO and about 210 ⁰ O, preferably about 160 to about 200 ⁰ C, and allowing sufficient pressure to act to achieve a firm adhesive connection. This result is also obtained when ^r either omitting the treatment with the inorganic acid solution or treatment with the second solution ·

Metal substrates such as aluminum, tinplate., Uiekel and EicQii, can when executing dea? Invention used will. Also other metals such as galvanized metals, magnesium or combinations of these with those mentioned above Metals, can be used.

The selected metal substrates are advantageously prepares or treats by first turning them into a practically salt-free, aqueous solution of an inorganic Brings acid that contains hexavalent chromium. One Chromium oxide treatment solution is used to perform the Invention preferred. However, mixtures of Chromium trioxide and other inorganic acids such as phosphoric acid, be used «This treatment can be replaced or followed by treatment with an ali-

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phatic carboxylic acid used to carry out the invention is suitable, for example maleic acid, citraconic acid, Acrylic acid, polyacrylic acid, pumaric acid, methacrylic acid, Crotonic acid, glutaric acid, itaconic acid and maleic acid (maleamic acid) Favorable concentrations for each of the above solutions range from about 0.1 to about 50 wt.? S (or up to the solubility limit) and before- ™ preferably at about 5 wt. ^ total acid, based on the

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Total weight of the solution. Depending on the particular verwen- - 'Deten acid and the treatment of the metal surfaces with concentrations leads up to 50 wt · f' either: ■ - aliphatic carboxylic acid or the. more inorganic. Acid solution also leads to very good adhesive bonds. However, the results obtained here are not noticeably better than the results obtained when using concentrations of about 5/6. The temperatures of the solution of the '| inorganic acid during the metal treatment are usually in the range of about 40 to about 100 ⁰ C, · pre preferably between about 70 and about 90 ⁰ C. The temperature of the solution of the aliphatic carboxylic acid should be at least 40 ⁰ C and preferably greater than 6O ⁰ C be.

• ■ * ·

The thermoplastic materials suitable for carrying out the invention include olefin polymer such as poly

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High and low density ethylene, polypropylene, poly-1-butene, copolymers of ethylene and propylene, mixtures of polymers of ethylene and the like. a pilm or powder »and can be of any thickness * suitable for the particular use. Fillers, such as buss, can be mixed into the polymeric coating material to provide additional desirable properties. The addition of such fillers does not significantly affect the adhesion of the polymer to the metal. '

The particular process of the invention results in laminates with unusually good properties the bond strengthThe laminates can be used, for example, for the production of wires and cables,

clothing, for adhesive protective coatings for the better Protection against chemicals and corrosion, construction adhesives, as packaging material and for panels with printed circuits.

The strength of the adhesive bond of the laminate makes it extremely resistant to the effects of moisture, and therefore the laminate is particularly suitable for protective covers.

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Pulls suitable for objects that are subject to long-term exposure to moisture are exposed· . .

The following examples illustrate the invention. At. ST) IeI 1 . .

A piece of soft-annealed solid aluminum foil of 15 × 20 σ 0.0114 cm was cleaned by immersing it in boiling perchlorethylene for 10 minutes. This cleaning step is not essential for the method of the invention, but is carried out as a precautionary measure to ensure a grease-free surface. After cleaning, the aluminum foil was air-dried for a sufficient time to allow the perchlorethylene to evaporate. Bann, the film was immersed for 5 minutes in a solution comprising> 50 g GRO (chromium trioxide) in one liter>'water, which kept at 80 ° C \ _t nxräe contained. After removing the metal foil from the immersion bath, excess adhering CrO ^ solution was washed off with ion-free water. The metallic metal was air dried at room temperature.

15 g high density polyethylene with a melt index of

below 3.0 were in a hydraulic press and: a pressure '

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molded of 7.7 kg / cm ² and at a temperature of 16O ⁰ C for 2 minutes. The polymer film obtained was cooled in a press and then removed. Its thickness was about 0.025 cm. The PiIm and the treated aluminum were brought together between poly (ethylene terephthalate) sliding plates and placed in the press under a pressure of 7.7 kg / cm at a temperature of 180 ⁰ C for 2 minutes connected long * The polyethylene-aluminum layer thus prepared was material for adhesion nac ^'1.' investigated the AS2M test method D9O3-49, but a cross-head separation speed of 10 cm / min -.-.- was applied and. the metal foil was peeled from the polymer. The peel or peel force measured in this test was 285.6 to 301.5 kg / m width (16 to 17 lbs. per inch)

In a comparative test, the peel strength was Determined by polyethylene, which is covered with an aluminum foil of the same type, but not according to the above The method described was treated, was connected It was only 8.93 ^ s / a width (0.5 Ib- per inch) when measuring under the same conditions «*

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Example .2

Eizv aluminum piece was made according to that described in Example 1 Procedure treated, however, the Ohromtri02ydlösung replaced by a solution containing a mixture of 50 g of chromium trioxide and 70 ml of phosphoric acid per liter of water · A polyethylene film was made with the most nimble Aluminum according to the method described in Example 1 " associated · The peel strength of the obtained Glued joint was 557 kg / m width »

Example 3

A piece of aluminum was treated according to the procedure described in Example 1. However, the Ohromtri oayd solution was replaced by a solution which had been prepared by hydrolysis of 50 g of maleic anhydride in 11 V / water treated aluminum according to the described procedure in example 1 _r comparable: y inhibited · the peel strength of the obtained Klebverbin- ν 'extension was 205 »3 kg / m width,"

Example 4 *

An aluminum piece was treated according to the procedure described in Example 1, after washing with ion-free

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Water, the aluminum foil was immediately immersed for 2 minutes in a maleic acid solution which had been prepared by hydrolysing 50 g of maleic anhydride in 1 1 V / water. After Behandlung.mit maleic aluminum foil washed again with ion-free * Water _ .and "at room temperature was allowed to air dry ^■:.. Once on the surface no more water was visible, the aluminum was as sufficiently dry for the connection A polyethylene film was bonded to the treated aluminum by the same method as in Example 1. The peel strength for the adhesive bond obtained was 357 to 410.5 kg / m width.

Example 5 ': -

Pieces of nickel and black plate were made after the in Example 1 described method treated and bonded with a polyethylene film. The peel strength was 123.9 kg / m width for the nickel laminates and 214.2 kg / m width 'for black sheet laminates.

Example 6

Another method used to measure the bond strength. an overlap shear test ·. Two aluminum pieces of

16 χ 10 χ Ο »16 cm were treated in the manner described in Example 1. A polyethylene film was also produced as described in Example 1. The two treated aluminum samples were placed on top of one another with an overlap of 1.27 cm on their 10 cm width with the polyethylene film in between. This arrangement was connected in a hydraulic press 2 Hinuten under a pressure of 4.2 kg / cm at a temperature of 200 C M. The overlapped bond was then determined according to ASTH 1GÖ2-535? Tested with an Instron-tTatörsuöh ^ migs device. Dung was 178.6 kg / cm ² (2540 psi).

Further tests showed that the "lap shear strength of a joint between untreated aluminum and a high density polyethylene was actually 0. _{/ jr}

In a comparative experiment, a solution that consists of a Mixture of 100 ml of sulfuric acid and 50 g of sodium dichromate was used instead of the chromium trioxide in Example 1. The treated metal became a polyethylene tied together. The overlap shear value was 102.6 kg / cm (1459 spi). The acid dichromate salt described above,

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The technical solution is currently for the connection of polyethylene used with metal substrates. You can see immediately that the laminate produced by the process according to the invention has a bond strength, which is more than 50 $ above the Sindefirmness that is obtained by the known methods.

Example 7

A sample of the fabric was prepared according to the procedure described in Example 4. The laminate, which had an initial peel strength of 423 "6 kg / m width", was placed in boiling water for about 16 hours in order to examine the strength of the adhesive bond under prolonged exposure to such conditions. Tests carried out following this exposure showed that the peel strength had remained the same. ■ "-

Example 8

Example 4 was essentially repeated, except that instead of maleic acid & e listed in Table I. organic acids were used. The peel strengths obtained are shown in the table.

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'Parts ϊ

Organic acid

Maleic acid citraconic acid acrylic acid Polyacrylic acid fumaric acid methacrylic acid Crotonic acid glutaric acid itaconic acid. - · Maleic acid

'' Peel strength in kg / m width for with CrO, + organic acid treated ^ metal

; ' 405, * . ■ · /,. 376, , 6. , / •. .371, 3 ■ 437, 3 · 339, 2 . .315, 9 328, 4th / 339, 2 339, 2 339, 2

example

A 1: 1 copolymer of ethylene and maleic anhydride was mixed with high density polyethylene. Then the procedure of Example 4 was substantially repeated, but has the high-density polyethylene is replaced by the above Polymerisatmischimg and an aluminum piece of 10 20 χ χ 0.305 cm used. The Gewiehtsprozent- B & tz of the added polyethylene interpolymer

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is based on the total weight of the mixed polymer it related «The peel strengths obtained are shown below ! Table II.

fork II

Percentage by weight of mixed peel strength in kg / m '/ polymer in polyethylene width i'

2. 624.8

3 "'. ■ 1196.0

Example 10

The procedure of. Example 2 was essentially repeated, but the ualoic anhydride was replaced by other organic ones. Acids replaced. The peel strengths obtained are shown in the following table äev III overall / ·.

Table III

Organic acid . '■ · Peel strength in kg / m width

Maleic acid ·.,. ·,. :. - "205 ₉ 3 citraconic acid". . · "173» 1

Acrylic acid 1o2 ₉ 4

Polyacrylic acid x 233.8

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Ports.! Table III

! Fumaric acid · itaconic acid maleamic acid 232.1 ■ it6.0 142.8

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Claims (1)

"'f.H2lf ffi' ^ntfert be the -16 - P A T E "Ν Ϊ A JJ S P Ii ü O H E. 1. A method for bonding thermoplastic materials to metal substrates, characterized in that the surface of the metal substrate with an essentially salt-free, aqueous solution of an inorganic acid, .die contains hexavalent chromium, and / or a solution which contains an aliphatic ^ carboxylic acid , treated, the metal was washed with water, the obtained treated metal was dried, © in © SöMe & t © i & §§ Olefin » polymerisates applied to the treated metal surface and applied heat and pressure to the superimposed structure is allowed to act · ■ 2. The method according to claim 1, characterized in that that as a substantially salt-free, aqueous solution of an inorganic Acid containing hexavalent chromium, a chromium trioxide solution is used '3 method laughing one of claims 1 and 2, characterized''in that the essentially salt-free aqueous solution of an "inorganic acid, hexavalent chromium, is maintained at a ffiemperatur ranging from 40 .to 1OQ ⁰ C. 10 9 8 2 7/1168 4. Process according to one of Claims 2 and 3, characterized in that the solution obtained is kept at a temperature between 70 and 90 ⁰ O during the treatment of the metal substrate surface. 5. The method according to claim 1, characterized in that the aliphatic carboxylic acid is maleic acid, citraoonic acid, Acrylic acid, polyacrylic acid, fumaric acid, methacrylic acid, .crotonic acid, glutaric acid, xtaconic acid or Maleamic acid is used. 6. The method according to any one of claims 1 and 5 », characterized in that the aliphatic © carboxylic acid is kept at a temperature of at least 40 ⁰ O. 7. Process according to one of claims 1, 5 and β, / characterized in that the temperature of the aliphatic "see carboxylic acid" is kept above 60 ^° C. 8th; Process according to one of Claims 1 to 7, characterized in that aluminum, nickel, iron or tinplate is used as the metal substrate. 109827/116 8 - ■■■ - · ■ ■ · ', ■■ 1β.6993Φ 9. The method according to any one of claims 1 "to 8, da- ^; by gelcennzeiohnei; ,, that polyethylene varwondet is used as olefin polymer.". 10- method according to one of claims 1 to 8 _g da-; characterized in that a mixture of ethylene and propylene, polybutene (1), polypropylene or a mixture of polyethylene and a mixture of ethylene and maleic anhydride is used as the olefin polymer ·>. ■ · · · - " ~ r ·. · 109 8 27/116 8