DE102007029100A1 - Method for joining two metal parts by means of welding - Google Patents

Abstract

Method for joining two metal parts by means of welding, in particular spot welding, by bringing the two metal parts to be welded into contact and being welded together at the point of contact, metal surfaces located near the welding location, which may be exposed to welding sparks or welding beads Adhesive tape are masked in particular against the Schweißfunken- or welding beads, wherein the adhesive tape has a carrier and a one-sided adhesive applied thereto, wherein the carrier is a film or a textile made of a self-extinguishing, flame-retardant or flame-retardant polymeric material and the adhesive chemically on nature or synthetic rubber based and wherein the adhesive tape has a total basis weight of at least 40 g / m <SUP> 2 </ SUP>, of which the carrier has a weight fraction of at least 50%.

Description

The The invention relates to a method for joining two metal parts by welding, being near the welding site surfaces protected against welding sparks should be.

The Production of an automobile body begins in the press shop with the Punching of roll-fed, galvanized steel and aluminum sheet to smaller sheet metal parts, the so-called boards. These are in the press lines by pulling, ie deforming of the material, cutting, folding (bending a narrow edge at the edge of the sheet metal part) or reshaping into the desired Brought form. To reduce the friction between the drawing tool and sheet metal are the sheets before the drawing process with drawing oils wetted, which on the one hand facilitates the drawing process, on the other hand a better surface quality of the three-dimensional deformed parts generated. The drawing oil remains on the Bleed until the shell is completed. It is only in the sun mentioned pretreatment with the aid of heated cleaning solution removed before the body is phosphated and in the subsequent Painting processes goes.

The numerous preformed body parts and sheet metal blanks today highly automated in welding lines assembled to the body. The items are ever Welded, glued or bonded according to location, function and material screwed. The robots not only take over the Task of welding, but also the handling of sheet metal parts, the precise fitting and fixing in the final Welding position.

In As a rule, production starts with welding together the bottom parts for the front and rear area. These the substructure forming assemblies are combined with other stabilizing elements connected to the body skeleton. If this with the page frames is connected, the later form of the bodywork is already clearly visible. Finally, the roof is welded on. Doors, tailgate and bonnet are manufactured separately.

Even though Even more modern welding processes such as laser welding Moving into the automotive industry, for example, often for Welding the roof section is the dominant one Welding still spot welding. In this resistance welding technique, the sheets to be joined become under high pressure with a welding tongs with copper electrodes punctiform compressed and by passing a Electricity is heated locally until it melts and so within seconds welded. Since the sheet metal parts to be joined their surfaces conduct relatively poorly, When the welding current is applied, a current breakdown occurs. in which the metal parts to be joined at their contact surface are suddenly heated and liquefied. It will be Welding sparks thrown away, sometimes up to several Fly far away.

One Sweat sparks is a liquid droplet Metal, due to its heat in contact with atmospheric oxygen oxidized while having a spark-like appearance. Meets This sparks on a body sheet, the metal droplets can become burn in the metal surface. Some sparks go out already during the flight and are then uncritical. This is the more likely the further the impact from the welding point is removed. The festgebreannten drops, however, are through the purification steps of pretreatment, unlike the cooled ones Drop, not removed. At the bodywork there is essentially an area that will be visible later: the page frame. Due to the location of the welding flanges land very many Sweat sparks in the door openings, which then become visible when you open the doors. In front the subsequent painting steps need the droplets be removed so that they do not have the visual impression of the paint to disturb. This happens manually manually today Scraping. The zinc coating can be injured and occasion for premature corrosion.

One effective way of preventing this manual rework is that Covering the affected sheet metal parts. It is on economy to pay attention, because covering in competition with manual rework stands. The covering solution must therefore be quickly applied be preferred (automatically by robot and under consideration the oiled surface), it must be inexpensive it must withstand the welding sparks (this may be so do not blow it or catch fire) and it must be quick without any restrictions be removable again.

Possible Covering solutions for the welding expert (and spread in other applications) make tapes and preformed hard masks, the latter being neither cost effective still fast (respectively automatic) are installable and thus no meaningful solution to the problem Offer.

Masking are variously available and include a variety of Support materials and self-adhesive compositions.

For Covering tasks particularly obvious are paper tapes, also called masking tapes, which consist of one with self-adhesive coated carrier made of impregnated paper exist and are very common for painting purposes. Even though most crepe tapes based on natural rubber or, more rarely, synthetic rubber, they are in welding processes not suitable because they are usually easily inflammable. One welding sparks incident on standard masking tapes burns quickly through the paper and can do so in the worst case even setting fire to fire, especially where the band is creasing or in the hollow to the primer because there is the heat can not be dissipated.

To the Covering and protecting will continue to be the most varied self-adhesive protective films offered. These usually exist from a foil, mostly polyethylene, more rarely polypropylene, the are equipped with acrylate adhesives. These do not build Adhesion to oiled bodywork sheets, as they do not absorb the oil, but this as a sliding layer between sheet and adhesive remains and so undesirable Slipping and peeling leads.

The significantly less numerous offered protective films with rubber adhesives Although in commercial form usually sufficient Liability, but not sufficient fire behavior.

For Masking applications are film tapes with a carrier made of soft PVC and for packaging applications with a hard PVC carrier, often even with a rubber adhesive, common. Although rigid PVC is inherently flame retardant is, develops when the welding sparks hit by decomposition of the PVC corrosive, gaseous Hydrogen chloride, which is the atmosphere of the factory building harmful to health. Soft PVC. develops as well Hydrogen chloride and unlike hard PVC is not as heavy to designate flammable.

Similar to classify films of fluorine-containing monomers such as polyvinylidene fluoride or polytetrafluoroethylene. Although these are even difficult to burn, they release highly toxic hydrogen fluoride on contact with welding sparks. Even though the amount is very low, the low MAK value (maximum workplace concentration) of 2 g / m ^{3 expresses} its high toxicity.

It are also self-adhesive metal foils, especially aluminum adhesive tapes, on offer. These are incombustible, over-fulfilling So the requirements of the fire behavior. Their disadvantage is the lack of adaptability to the generally domed Primer geometries. In addition, there is a risk of demasking Injury to the sometimes sharp-edged film parts. Farther tear self-adhesive aluminum foils when unmasking very easily, which makes the demasking process and the welding process unnecessarily extended.

• • rasch und sicher auf dem mit Ziehöl behafteten Rohbaublech haftet,
• • eine für eine gute Aufbringbarkeit ausreichende Flexibilität hat,
• • das Einbrennen der Schweißfunken in das Blech sicher verhindert,
• • keine Gefahr der Entzündung durch Schweißfunken birgt,
• • sich leicht und ohne Rückstände nach abgeschlossenem Schweißprozess vom Rohbaublech wieder entfernen lässt,

so dass das Schweißverfahren von Nachbearbeitungsschritten der gefügten Teile befreit und somit insgesamt optimiert ist.The object of the present invention is to provide a welding method for joining two metal parts, in particular car body sheets, in which exposed metal surfaces are protected against the burning-in of welding sparks by masking, wherein the masking

• • adheres quickly and safely to the shell sheet covered with drawing oil,
• • has sufficient flexibility for good application,
• • reliably prevents the welding sparks from being burned into the metal sheet
• • no risk of ignition due to welding sparks,
• • can easily be removed from the raw sheet metal after the welding process has been completed without residues,

so that the welding process of post-processing steps of the joined parts freed and thus optimized overall.

Solved This task is performed by a welding process, as it is in Main claim is laid down. Subject of the dependent claims are advantageous developments of the invention.

Accordingly, the invention relates to a method for joining two metal parts by means of welding, in particular spot welding, by bringing the two metal parts to be welded into contact and welding them together at the point of contact, metal surfaces located near the welding location, which possibly has a welding or welding bead flight are masked by an adhesive tape in particular against the welding sparks or weld beads, wherein the adhesive tape has a backing and an adhesive applied on one side thereof, wherein the backing is a film or textile of a self-extinguishing, flame-retardant or flame-retardant polymeric material and the adhesive is chemically based on natural or synthetic rubber and wherein the adhesive tape has a total basis weight of at least 40 g / m ² , of which the carrier has a weight fraction of at least 50%. The adhesive tape preferably has a total thickness of at least 40 μm.

Preferably Bodywork sheets are used against welding sparks with the help masked by an adhesive tape. In particular, these are sheets, which later form a door opening in the car.

The there is suitable adhesive tape for the masking solution from a carrier and a one-sided applied thereto Self-adhesive, where the total thickness, ie the sum of the two Layers, including functional layers described below, a value of 40 microns may not fall below, otherwise the welding sparks are not effectively prevented from burning through become. Both the carrier and the adhesive carry together to protect against burning.

The adhesive tape has a total basis weight, ie the sum of the basis weights of carrier, adhesive and, if appropriate, further functional layers of at least 40 g / m ² , the carrier having a weight fraction of the total weight of the adhesive tape of at least 50%.

On On the other hand, it is possible to use carrier materials to find that either inherently or by adding Flame retardants meet the required difficult flammability, However, self-adhesives are inherently non-inherent hardly flammable and can only be under significant impairment their adhesive properties in their flame resistance improve. It has been shown that at a weight percentage of Carrier at the total weight of the tape of at least 50% for an application - appropriate flame retardancy of the Masking solution, the flammability of the adhesive tape sufficient is low, if the carrier itself from a self-extinguishing or flame-retardant or flame-retardant material. This restriction assumes that the welding sparks as in the real case of a glued tape on the carrier meet, with the self-adhesive is shielded by this.

in principle suitable as a carrier material for a the masking solution provided tape are films or Textiles such as fabrics, nonwovens or knits.

suitable In particular, materials for films are inherent flame retardant plastics such as polyester (polyethylene terephthalate, glycol-modified polyethylene terephthalate, polybutylene terephthalate, Polyethylene naphthalate) or polycarbonate.

The Most other common plastics used in industrial Film production are common, typically polyolefins, Polyamide or polyurethane, can by flame retardants be set sufficiently flame retardant, the proportion of Flame retardants in particular between 5 and 60 weight percent lies.

The inherently flame resistant plastics can improved by fire retardants again in their fire behavior become.

When Polyolefins are typically used in polyethylene, polypropylene as well as their mixtures or copolymers (for example random copolymer or polypropylene block copolymer) or copolymers of ethylene and α-olefins such as 1-butene, 1-hexene, 1-octene (depending on the proportion and method of preparation LLDPE, VLDPE or ULDPE or metallocene PE), but also ethylene-styrene copolymers, Ethylene with polar comonomers such as acrylic acid and copolymers propylene with α-olefins, such as ethylene, 1-butene, 1-hexene or 1-octene.

polyamide usually includes polymethyl methacrylate or impact resistant modified polymethylmethacrylate.

polyurethane films consist of either thermoplastic polyurethane or be for example, from the reactive building blocks aromatic or aliphatic Isocyanates (such as hexamethylene diisocyanate, isophorone diisocyanate, Diphenylmethane diisocyanate or tolylene diisocyanate) with two- or made of polyhydric polyester or polyether alcohols.

The Films can be used as monofilm or as coextrudate, as cast film or blown film, mono- or biaxially stretched or unstretched be executed.

According to the state of the art, all films may be provided with the additives known in the art, including anti-aging agents, fillers, pigments, antiblocking agents, lubricants, nucleating agents or antistatic agents. Detailed embodiments can be found in the literature, for example, relevant textbooks such Gächter / Müller, Handbuch der Kunststoffadditive, 3rd edition, Carl Hanser Verlag 1990 , These additives serve for improved processability, processability in subsequent processing steps or optical design from an aesthetic or functional point of view.

Prefers suitable textile materials, like the films, are those which are inherently flame retardant, especially the Polyester fiber Polyethylene terephthalate, aromatic polyamide fibers like Nomex or Kevlar and wool.

Also other non-inherently flame retardant fiber materials such as cotton, rayon, polyamide 6 or 66, polyolefins, Cellulose acetates or polyacrylonitrile are useful when combined with Flame retardants are equipped, in particular to a Proportion of 5 to 40 wt .-%. Unlike foils, the flame retardants not incorporated into the fiber material, but the textile Surface product (fabric, fleece, knitted fabric) is through Impregnated with suitable substances in its burning behavior improved. This is usually done with the padding process in which the web-shaped fabric with a solution or dispersion of the flame retardant soaked and then squeezed off or simply by spraying and then drying.

For an adhesive tape application where the fabric is used only once is already a non-washable flameproof equipment with salts such as diammonium phosphate, boric acid, aluminum sulfate, ammonium sulfate, Zinc chloride, phosphates, ammonium salts or mixtures of these, as it is especially suitable for cotton and rayon, sufficient. This textile group may also be due to phosphorylation with phosphoric acid and urea in flame retardancy be improved.

A very stable and for most fiber types suitable flameproofing equipment is used with the group of tetrakis (hydroxyalkyl) phosphonium chlorides (THCP), which with urea into a stable aqueous Solution transferred and with ammonia or Ammonium hydroxide permanently fixed after impregnation can be. There are numerous variants depending on the purpose in Use. In the THCP amide process, the fixation is for example with Urea, trimethylolmelamine and sodium hydroxide achieved.

The basis weight of the carrier is at least 20 g / m ² . Basis weights of the carrier less than 40 g / m ² must be combined with so much adhesive that the total basis weight of the present invention of 40 g / m ² is achieved at least to prevent the welding sparks effectively by blowing. The carrier must not be less than 50% by weight of the total weight of the adhesive tape. Upwards, there is no fundamental limitation. A maximum total basis weight results from restrictions in the handling in the application and the economy.

Self-adhesives for the masking solution adhesive tape include resin blended Natural rubber and synthetic rubber formulations, the latter for Example based on hydrogenated or unhydrogenated styrene block copolymers, Styrene butadiene rubber, butyl rubber, polyisobutylene, ethylene-propylene copolymers or nitrile rubber, and mixtures of these.

The Elastomer forms the basis of each self-adhesive and determines their characteristics prevail. To optimize the adhesive technology Properties, must be used with self-adhesive one or more additives such as tackifiers (resins), plasticizers, Fillers, pigments, UV absorbers, light stabilizers, anti-aging agents, Crosslinking agents or crosslinking promoters be blended.

in principle also the self-adhesive compositions with flame retardant additives, as mentioned under the description of the film carrier are improved in their burning behavior, especially when these are added in a proportion of 2 to 30 wt .-%.

Tackifiers are, for example, hydrocarbon resins (for example from unsaturated C ₅ or C ₇ monomers), terpene-phenolic resins, terpene resins from raw materials such as α- or β-pinene, aromatic resins such as cumarone-indene resins or resins of styrene or α-methylstyrene and rosin and its derivatives such as disproportionated, dimerized or esterified resins, wherein glycols, glycerol or pentaerythritol can be used and others as listed in Ullmann's Enzyklopadie der technischen Chemie, Volume 12, pages 525 to 555 (4th edition), Weinheim , The resins may also be hydrogenated, thus showing less sensitivity to aging.

suitable Fillers and pigments are, for example, carbon black, Titanium dioxide, calcium carbonate, zinc carbonate, zinc oxide, silicates or Silica.

For suitable UV absorber, sunscreen and aging inhibitor on the same source as for the additives for the film carriers referenced.

suitable Plasticizers are, for example, aliphatic, cycloaliphatic and aromatic mineral oils, di- or poly-esters of phthalic acid, Trimellitic acid or adipic acid, liquid Rubbers (for example nitrile or polyisoprene rubbers), liquid Polymers of butene and / or isobutene, acrylic esters, Polyvinyl ethers, liquid and soft resins based on raw materials from adhesive resins, wool wax and other waxes or liquid Silicones.

crosslinking agent are, for example, alkylphenol resins or halogenated phenolic resins, Melamine and formaldehyde resins or isocyanates. Suitable crosslinking promoters are, for example, maleimides, allyl esters such as triallyl cyanurate, polyfunctional esters of acrylic and methacrylic acid.

A Networking can also be done by electron beams.

The Formulation of the adhesives may be carried out in suitable solvents or solvent mixtures (for example, gasoline, toluene, Alcohols), dry in suitable aggregates (for example planetary roller wipers) or in the aqueous phase as a dispersion.

The Coating the adhesives on the carrier then takes place correspondingly from solution, from aqueous dispersion or dry, for example by means of a rolling mill or calendering technology.

A Alternative to direct coating of the carrier is the indirect way, in which an abhesive equipped Subcarrier (release paper or release film) is coated and the dried adhesive in the transfer process to the carrier is laminated.

Suitable examples of flame retardant additives are brominated flame retardants such as tetrabromobisphenol A bis (2,3-dibromopropyl ether), ethylene bis (tetrabromophthalimide) or ethylene bis (dibromonorbornandicarboximide), especially in combination with antimony trioxide or zinc borate, but also halogen-free variants such as ammonium polyphosphates, Pentaerythritol melamine derivatives and / or inorganic compounds such as Al (OH) ₃ or Mg (OH) ₂ .

These are added directly to the films during their production and are Part of the recipe.

The Anchoring of the self-adhesive can be achieved by coating with a primer can be improved as an anchoring aid. This can also a corona or a flame pretreatment of the to be coated Serve film side.

On the back of the tape can be a backside paint be applied to the rolling properties of the Archimedean Spiral coiled tape to favorably influence. This backside lacquer can do this with silicone or fluorosilicone compounds and with polyvinyl stearyl carbamate, polyethyleneimine stearyl carbamide or fluoroorganic compounds as abhesive Be equipped fabrics.

Optional For example, the suitable adhesive tape for the masking solution Covered with a release paper or a release liner (that are typically silicone-coated papers or plastic films) be presented.

Of the general term "adhesive tape" covers the meaning of this Invention all planar structures as in two dimensions extended films or film sections, tapes with extended Length and limited width, band sections, die cuts and the same.

The rubber compounds described absorb the oil after a short time and already provide Immediately after sticking to the oiled substrate and with time increasing for safe adhesion of the adhesive tape.

In the usually encountered drawing oil quantities of a few grams per square meter, a weight per unit area of the adhesive greater than 10, preferably greater than 20 g / m ^{2 is} required so that the oil can be completely absorbed. The basis weight of the adhesive must not exceed a proportion of 50% of the total weight per unit area of the adhesive tape.

• • eine rasche und sichere Haftung auf dem mit Ziehöl behafteten Rohbaublech,
• • eine ausreichende Flexibilität für eine ausreichende Aufbringbarkeit,
• • einen sicheren Schutz gegen Einbrennen der Schweißfunken in das Blech,
• • keine Gefahr der Entzündung durch Schweißfunken und
• • eine leichte Entfernbarkeit ohne Klebmasserückstände auf dem Rohbaublech.

The masking solution according to the invention with the aid of an adhesive tape meets all the requirements that are imposed on a clean and fast welding process. The tape shows

• • rapid and secure adhesion to the shell sheet bearing draw oil,
• Sufficient flexibility for adequate application,
• Safe protection against burning in of the welding sparks,
• • no risk of ignition due to welding sparks and
• • easy removability without adhesive residue on the shell.

By the masking thus results in a very advantageous course of the entire welding process when joining two Parts, because all requirements are fulfilled respectively the known disadvantages of the prior art are avoided.

The proposed solution is easy by hand or inexpensively automated with the help of a robot Apply to bodywork sheets, especially in the door cutouts the side frame especially affected by the welding spark. There is a sufficient immediate liability, even if the Sheet metal is covered with drawing oils, so that neither the masking process is still obstructed by slipping on the bodywork sheet the masking falls prematurely under the influence of its own weight. In the case of oil occupancy of the sheet sucks the adhesive based on natural or synthetic rubber, the oil, wherein the adhesion to the body shell sheet within a short time Time increased. The tape provides sufficient protection against Sweat sparks, as they burn into the tape, but not to penetrate to the body shell plate. The masking solution is flame retardant even with strong flying sparks in hollow layers, where the tape has no contact with the underlying sheet metal and the heat resulting from the impact of the sparks can not be dissipated by this.

To the welding process, at the latest before the pretreatment for the subsequent painting processes, leaves Masking the tape easily and without lasting damage replace the primer. Any remaining minor Adhesive residues are in the washing steps the pre-treatment easily removed.

at Use of the disclosed adhesive tapes in an inventive Welding process offers the further advantage that the bead of sweat, which after cooling the Welding spark remains, firmly with the carrier connects and does not break away from this and dirty the work area.

With the masking solution in the inventive Welding process labor-intensive and cost-intensive reworking in the form of the mechanical removal of in bodywork sheets burned beads of sweat and at the same time the danger the violation of the corrosion-inhibiting zinc layer in their mechanical Distance avoided.

For the welding method according to the invention suitable adhesive tapes used for masking can be, are below in a preferred embodiment described with reference to several examples, without the invention to subject to any restriction.

Of Further, comparative examples are listed in which Welding adhesive tapes unfit for welding are shown.

Examples

to Illustration of masking solutions are in the form of examples Constructions of adhesive tapes described that a suitable Masking solution and in the form of counterexamples which, with which no suitable masking solution can be achieved.

Adhesive tape for example 1

A polyester fabric of polyethylene terephthalate fibers having a basis weight of 130 g / m ² is used in a laboratory coating system with a natural rubber self-adhesive coating consisting of 55 parts natural rubber, 5 parts zinc oxide, 6 parts rosin glycerol ester resin, 6 parts alkyl phenol resin, 26 parts hydrocarbon resin and 2 parts mineral oil Natural rubber self-adhesive composition is dissolved in a mixture of gasoline 60/95 and toluene in a ratio of 4: 1 parts, coated so that after drying at up to 120 ° C, an application weight of 80 g / m ² results. The fabric adhesive tape is wrapped storable on itself into a roll.

Adhesive tape for example 2

Such as adhesive tape for Example 1, but to an aramid fabric (aromatic polyamide, Nomex ^®) is used with a basis weight of 61 g / m ^2. The coating weight of the self-adhesive is 52 g / m ² .

Adhesive tape for example 3

As for adhesive tape for Example 1, in contrast to a cotton fabric with a basis weight of 120 g / m ² , equipped with the flame retardant Afflamit KWB (Thor Chemie) is used. The coating weight of the self-adhesive is 70 g / m ² .

Adhesive tape for example 4

As for adhesive tape for Example 1, by contrast, a biaxially stretched film of polyethylene terephthalate having a basis weight of 50 g / m ^{2 is} coated. This is primed before coating with the self-adhesive with a solution of 2 parts of natural rubber in toluene, which has been mixed with 1 part of diphenylmethane diisocyanate, with a coating weight of 0.3 g / m ² . The coating weight of the self-adhesive is 25 g / m ² .

Adhesive tape for example 5

Such as adhesive tape for Example 1, but to a sheet of polyimide (Kapton ^® HN from DuPont) having a basis weight of 27.8 g / m ² is coated. The coating weight of the self-adhesive is 20 g / m ² .

Adhesive tape for example 6

As for adhesive tape for Example 1, by contrast, a film of a 50:50 blend of polypropylene homopolymer and Polypropylenrandomcopolymer with 4 mole percent ethylene content with an addition of 30 wt .-% ammonium polyphosphate as a flame retardant with a weight of 70 g / m ² coated. The coating side of the film is pretreated with corona discharge and primed with a 50:50 mixture of a centrifuge latex and a nitrile rubber latex having a basis weight of 0.8 g / m ² . The coating weight of the self-adhesive is 25 g / m ² .

Adhesive tape for example 7

As with adhesive tape for Example 1, by way of exception, a self-adhesive based on styrene block copolymers consisting of 50 parts Kraton G 1650 (Kraton), 50 parts Kraton G 1657 (Kraton), 90 parts Regalite R 1100 (Eastman), 20 parts Regalite R 1010 (Eastman) and 2 parts Irganox 1010 (Ciba) mixed in a twin-screw extruder and coated with a slot die on the fabric. The coating weight of the self-adhesive is 25 g / m ² .

Adhesive tape for counterexample 1

As for adhesive tape for Example 1, in contrast to a self-adhesive composition based on a Acrylsäureesterpolymerisates copolymerized from 50 parts of butyl acrylate, 32 parts of 2-ethylhexyl acrylate, 10 parts of vinyl acetate, 5 parts of methyl acrylate and 3 parts of acrylic acid crosslinked with 0.3 wt .-% Aluminiumacetylacetonat in a solvent mixture of 40 parts toluene, 40 parts ethyl acetate and 20 parts isopropanol. The film is previously admixed with a polyvinylidene dichloride solution having an application weight of 0.8 g / m ² Liability improvement primed.

Adhesive tape for counterexample 2

As for adhesive tape for Example 1, in deviation to a support made of aluminum foil of thickness 35 microns with an adhesive coating of 20 g / m ² coated.

Adhesive tape for counterexample 3

As Adhesive tape for example 3, but not in the same way coated with flame retardant cotton fabric coated.

Adhesive tape for counterexample 4

Like adhesive tape for example 4, in contrast to this, a PET film with a basis weight of 20 g / m ² and an adhesive application of 15 g / m ^{2 is} selected.

Adhesive tape for counterexample 5

As for adhesive tape for Example 1, by contrast, a biaxially stretched film of polyethylene terephthalate having a basis weight of 50 g / m ^{2 is} coated. The coating weight of the self-adhesive is 70 g / m ² .

Adhesive tape for counterexample 6

It is a commercial Papierabdeckband (Malerkrepp with Natural rubber self-adhesive composition), article number 4323, from tesa AG used.

Adhesive tape for counterexample 7

It is a commercial packaging tape with a monoaxially stretched polypropylene carrier and a synthetic rubber self-adhesive composition, Item number 4287, which uses tesa AG.

test criteria

• • Schälkraft der Klebebänder von mit Ziehöl belegtem Karosserierohbaublech sofort nach der Beklebung
• • Ausreichende Flexibilität des Trägers für eine rasche und problemlose Aufbringung
• • Sicheres Verhindern des Einbrennens von Schweißfunken durch das Band hindurch in das Karosserierohbaublech
• • Keine Entflammbarkeit des Klebebandes durch Schweißfunken
• • Schälkraft der Klebebänder von mit Ziehöl belegtem Karosserierohbaublech 3 Tage nach der Beklebung, dabei kein Verbleiben von Klebmasserückständen auf dem Blech

The following relevant parameters are used to assess the suitability of a masking solution against welding sparks:

• Peeling force of adhesive tapes of bodywork sheet covered with drawing oil immediately after bonding
• • Sufficient flexibility of the carrier for quick and easy application
• • Safely preventing the welding sparks from being burned through the belt into the body shell
• • No flammability of the adhesive tape due to welding sparks
• Peeling force of the adhesive tapes of bodywork sheet covered with drawing oil 3 days after the gluing, with no remaining adhesive residue on the sheet

Carrying out the Testing

Peeling force of adhesive tapes immediately after with occupied by drawing oil bodywork sheet metal the sticker

The substrate used is galvanized body sheet, which is coated with approx. 3 g / m ^{2 of} Palatinol B804 / 3C OW (Oest) drawing oil. On this is a peel force test based on ASTM D3330 carried out. For this purpose, the 2 cm wide and 20 cm long specimen is placed with the adhesive side on the oiled substrate and pressed by rolling ten times with a 4 kg pressure roller. The peel angle when peeling with a tensile tester is 180 °, the take-off speed 300 mm / min. The peel force is measured within five minutes of sticking.

Rating:

• +

  for one Measured value of at least 0.2 N / cm

  -

  for one Measured value less than 0.2 N / cm

Sufficient flexibility of the Support for a quick and easy application

When The test object is a scrap vehicle from Mercedes Benz (230 E, W124), analogous to the application in the body shell of the door opening the driver's door of the side frame with the door removed is stuck by three subjects. Although the test object is painted, but it is still with the drawing oil Palatinol B804 / 3C OW (Oest) coated to the sliding properties of the surface to simulate. Adhesion properties are not rated, but only the handling of the different test tapes when applied in terms of their adaptability to the irregular primer geometry. The subjects must judge their impression of manageability.

Rating:

• +

  for one mostly positive impression

  -

  for one mostly negative impression

Safely preventing the burning in of Welding sparks through the belt into the body shell

For Welding sparks are analogous to those in the welding lines produced by automobile plants. These are two each 1 mm thick galvanized Shell sheets with an air-cooled spot welding gun (Tecna 3580) with 12 mm electrode diameter and 5 mm diameter of the electrode tip with a forceps pressure of 1.5 kN and 7 kA welding current spot welded. A square galvanized body panel with an edge length of 75 cm becomes full surface stuck with the test tapes and half a meter placed flat below the welding zone, leaving a large part of the welding sparks fall on the sheet.

After this at least twenty sparks have burned out on the sheet, the adhesive tapes are peeled off and judged whether or not Sweat sparks through the tape into the sheet have burned.

Rating:

• +

  at no in the Sheet metal burnt sparks

  -

  at least one Welding sparks burnt into the sheet

No inflammability of the adhesive tape by welding sparks

When Ignition source becomes the same spot welding construction as used above. In contrast, the tapes are clamped freely without substrate contact to the heat dissipation to prevent. The welding sparks thus fall on the carrier side the tapes. A smoke development of the struck Jobs are allowed.

Rating:

• +

  If no glow or triggered no inflammation of the tape has been

  -

  If no glow or triggered no inflammation of the tape has been

Peeling force of adhesive tapes of bodywork covered with drawing oil 3 days after the gluing, while remaining no adhesive residues on the tin

The substrate used is galvanized body sheet, which is coated with approx. 3 g / m ² drawing oil Palatinol 8804 / 3C OW (Oest). On this is a peel force test based on ASTM D3330 carried out. For this purpose, the 2 cm wide and 20 cm long specimen is placed with the adhesive side on the oiled substrate and pressed by rolling ten times with a 4 kg pressure roller. The peel angle when peeling with a tensile tester is 180 °, the take-off speed 300 mm / min. The peel force is measured 72 hours after sticking. After peeling is visually assessed for adhesive residues.

Evaluation peeling force:

• +

  for one Measured value of at least 1 N / cm

  -

  for one Measured value less than 1 N / cm

Assessment of adhesive residues:

• +

  for none Adhesive residue or minor traces

  -

  for obvious or even full-surface adhesive residues

Results

The Results of the masking solutions are in the following table summarized. In this case, the non-fulfillment is sufficient of a criterion to disqualify the masking solution altogether for the welding process according to the invention to rate.

Rating:

• +

  Overall rating: suitable masking solution

  -

  Overall rating: disabled masking solution

  

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - Gächter / Müller, Handbuch der Kunststoffadditive, 3rd edition, Carl Hanser Verlag 1990 [0031]
• - Ullmann's Enzyklopadie der technischen Chemie, Volume 12, pages 525 to 555 (4th edition), Weinheim [0040]
• ASTM D3330 [0081]
• ASTM D3330 [0086]

Claims (13)

Method for joining two metal parts by means of welding, in particular spot welding, by bringing the two metal parts to be welded into contact and welding them to one another at the point of contact, metal surfaces located near the welding location, which may be subject to welding or welding bead flying Adhesive tape are masked in particular against the Schweißfunken- or welding beads, wherein the adhesive tape has a carrier and a one-sided adhesive applied thereto, wherein the carrier is a film or a textile made of a self-extinguishing, flame-retardant or flame-retardant polymeric material and the adhesive chemically on nature or synthetic rubber based and wherein the adhesive tape has a total basis weight of at least 40 g / m ² , of which the carrier has a weight fraction of at least 50%. A method of joining according to claim 1, characterized characterized in that the metal parts are body shell sheets, especially the sheets, which later in the car a door opening form. Method for joining after at least one of the preceding claims, characterized in that the carrier of the adhesive tape of a foil or of a Textile such as fabric, nonwovens or knitted fabric consists. Method for joining after at least one of the preceding claims, characterized in that flame retardants are added to the carrier of the adhesive tape. Method for joining after at least one of the preceding claims, characterized in that the film of the carrier of the adhesive tape is selected from the group polyester (polyethylene terephthalate, glycol-modified Polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate) or polycarbonate. Method for joining after at least one of the preceding claims, characterized in that the film of the carrier of the adhesive tape is selected from the group polyolefins, polyamide or polyurethane, these being are equipped with flame retardants, in particular to in a proportion of 5 to 60 wt .-%. Method for joining after at least one of the preceding claims, characterized in that the textile of the carrier of the adhesive tape of polyester fibers such as polyethylene terephthalate, aromatic polyamide fibers such as Nomex or Kevlar and / or wool or the fiber materials of the Textiles such as cotton, rayon, polyamide 6 or 66, polyolefins, Cellulose acetate or polyacrylic with flame retardants are, in particular to a proportion of 5 to 40 wt .-%. Method for joining after at least one of the preceding claims, characterized in that as a flameproof finish for the fibers of the textile Carrier salts such as diammonium phosphate, boric acid, aluminum sulfate, Ammonium sulfate, zinc chloride, phosphates, ammonium salts or mixtures of these, and / or the group of tetrakis (hydroxyalkyl) phosphonium chlorides (THCP). Method for joining after at least one of the preceding claims, characterized in that the adhesive on hydrogenated or unhydrogenated styrene block copolymers, Styrene butadiene rubber, butyl rubber, polyisobutylene, ethylene-propylene copolymers or nitrile rubber, as well as mixtures of these. Method for joining after at least one of the preceding claims, characterized in that the adhesive mass flame retardant additives are added, in particular in a proportion of 2 to 30 wt .-%. Method for joining after at least one of the preceding claims, characterized in that the adhesive with one or more additives such as tackifiers (Resins), plasticizers, fillers, pigments, UV absorbers, Light stabilizers, anti-aging agents, crosslinking agents or crosslinking promoters is mixed. Joining method according to at least one of the preceding claims, characterized in that as flameproofing agents brominated flame retardants such as tetrabromobisphenol A bis (2,3-dibromopropyl ether), ethylene bis (tetrabromophthalimide) or ethylene bis (dibromonorbornandicarboximid), especially in combination with Antimony trioxide or zinc borate, halogen-free variants such as ammonium polyphosphates, pen taerythritol melamine derivatives and / or inorganic compounds such as Al (OH) ₃ or Mg (OH) ₂ are used. Method for joining according to at least one of the preceding claims, characterized in that the adhesive is applied with a basis weight of greater than 10, preferably greater than 20 g / m ² on the carrier.