POLYOLEFIN HOT-MELT GLUE HAVING A LOW REACTIVATION TEMPERATURE AND HIGH HEAT STABILITY AND USE THEREOF FOR VACUUM DEEP-DRAWING LAMINATION

Abstract

A hot-melt glue composition, including a) at least one atactic poly--olefin (APAO) that is solid at 25 C.; b) at least one hydrocarbon resin having a softening point of at least 80 C., measured in accordance with the ring-and-ball method according to DIN EN 1238; and c) at least one maleic-anhydride-grafted wax having a softening point of not more than 150 C., measured in accordance with the ring-and-ball method according to DIN EN 1238, which is a maleic-anhydride-grafted polypropylene wax or a maleic-anhydride-grafted polyethylene wax, wherein the proportion of the at least one maleic-anhydride-grafted wax in the hot-melt glue composition is at least 3 wt %. The hot-melt glue composition is characterized by a low reactivation temperature, together with high heat resistance and good adhesion to ABS and nonpolar polyolefin materials. The hot-melt glue composition is well suited for film lamination by vacuum deep-drawing lamination, in particular for applications in automobile construction.

Claims

1. A hotmelt adhesive composition comprising a) at least one atactic poly--olefin (APAO) which is solid at 25 C.; b) at least one hydrocarbon resin having a softening point of at least 80 C., measured by the ring & ball method according to DIN EN 1238; and c) at least one maleic anhydride-grafted wax having a softening point of not more than 150 C., measured by the ring & ball method according to DIN EN 1238, which is a maleic anhydride-grafted polypropylene wax or a maleic anhydride-grafted polyethylene wax, where the fraction of the at least one maleic anhydride-grafted wax in the hotmelt adhesive composition is at least 3 wt %.

2. The hotmelt adhesive composition as claimed in claim 1, wherein the atactic poly--olefin (APAO) has a softening point in the range from 70 C. to 170 C., measured by the ring & ball method according to DIN EN 1238.

3. The hotmelt adhesive composition as claimed in claim 1, wherein the atactic poly--olefin (APAO) has a softening point in the range from 80 C. to 150 C. measured by the ring & ball method according to DIN EN 1238.

4. The hotmelt adhesive composition as claimed in claim 1, wherein the maleic anhdride-grafted wax has a softening point in the range from 100 C. to 150 C.

5. The hotmelt adhesive composition as claimed in claim 1, wherein the hydrocarbon resin is an aliphatic C5-C9 hydrocarbon resin.

6. The hotmelt adhesive composition as claimed in claim 1, wherein it comprises a) 40 to 85 wt % of the at least one atactic poly--olefin (APAO); and/or b) 5 to 30 wt % of the at least one hydrocarbon resin; and/or c) 3 to 20 wt % of the at least one maleic anhydride-grafted wax.

7. The hotmelt adhesive composition as claimed in claim 1, wherein it comprises 7 to 13 wt % of the at least one maleic anhydride-grafted wax.

8. The hotmelt adhesive composition as claimed in claim 1, wherein it has a softening point in the range from 100 to 160 C. measured by the ring & ball method according to DIN EN 1238.

9. The hotmelt adhesive composition as claimed in claim 1, wherein the hydrocarbon resin has a softening point of at least 90 C., measured by the ring & ball method according to DIN EN 1238.

10. The hotmelt adhesive composition as claimed in claim 1, wherein the fraction of further thermoplastic polymers which differ from a) the atactic poly--olefin (APAO), b) the hydrocarbon resin, and c) the maleic anhydride-grafted wax in the hotmelt adhesive composition is less than 5 wt %, or the hotmelt adhesive composition contains substantially no further thermoplastic polymers.

11. The hotmelt adhesive composition as claimed in claim 1, wherein it is a nonreactive polyolefin hotmelt adhesive.

12. A method comprising laminating a foil with a hotmelt adhesive composition as claimed in claim 1.

13. The method as claimed in claim 12, wherein the laminating is for vehicle construction.

14. A method for producing an assembly composed of a substrate element and a foil by adhesive bonding, the method comprising the following steps: a) the applying of a hotmelt adhesive composition as claimed in claim 1 to one side of a foil; b) the heating of the foil coated with the hotmelt adhesive composition, for reactivating, and c) the drawing of the reactivated foil, coated with the hotmelt adhesive composition, onto the substrate element, with the hotmelt adhesive composition coming into contact with the substrate element and, after cooling, producing the bonded assembly.

15. The method as claimed in claim 14, wherein the foil is a TPO foil and/or the substrate element, or the surface of the substrate element to be laminated, is made of a polypropylene, natural-fiber or ABS material, and/or the film is drawn onto the substrate element by vacuum forming lamination or IMG lamination.

16. An assembly obtainable by a method as claimed in claim 14.

Description

CERTAIN EMBODIMENTS OF THE INVENTION

[0030] The softening point in the present document is understood in each case to be the softening point as measured by the ring & ball method according to DIN EN 1238, unless otherwise indicated.

[0031] Molecular weight is understood in the present document to be the number average of the molecular weight (Mn). The molecular weight may be determined by gel permeation chromatography (GPC) with styrene as standard.

[0032] The quantity figures are always based on the total weight of the hotmelt adhesive composition, unless otherwise indicated.

[0033] Abbreviations used are as follows: [0034] ABS acrylonitrile-butadiene-styrene [0035] APAO atactic poly--olefin, also referred to as amorphous poly--olefin [0036] HC hydrocarbon [0037] TPO thermoplastic, olefin-based elastomer

[0038] The expressions hotmelt adhesive composition, hotmelt adhesive, and hotmelt are used below as synonymous expressions.

[0039] In a first aspect, the present invention relates to a hotmelt adhesive composition which comprises [0040] a) at least one atactic poly--olefin (APAO) which is solid at 25 C.; [0041] b) at least one hydrocarbon resin having a softening point of at least 80 C., measured by the ring & ball method according to DIN EN 1238; and [0042] c) at least one maleic anhydride-grafted wax having a softening point of not more than 150 C., measured by the ring & ball method according to DIN EN 1238, which is a maleic anhydride-grafted polypropylene wax or a maleic anhydride-grafted polyethylene wax,
where the fraction of the at least one maleic anhydride-grafted wax is at least 3 wt %.

[0043] The composition of the invention is in particular a nonreactive polyolefin hotmelt adhesive, more particularly a nonreactive poly--olefin hotmelt adhesive, meaning that the APAO in the hotmelt adhesive composition has no reactive groups via which chemical crosslinking would be possible, such as silane groups, for example. Hence, for example, the hotmelt adhesive composition contains in particular no APAO containing silane groups.

[0044] The atactic poly--olefin which is solid at 25 C. is, in particular, thermoplastic. The APAOs may be homopolymers or copolymers. The copolymers may for example be polymers of two, three or more olefin monomers.

[0045] Atactic poly--olefins can be prepared by polymerization of -olefins, more particularly of ethene, propene and 1-butene, usingfor exampleZiegler catalysts. The APAOs may be homopolymers or copolymers of -olefins. Relative to other polyolefins, they have an amorphous structure.

[0046] An -olefin is understood in this document, in the usual definition, to be an alkene with the empirical formula C.sub.xH.sub.2x that has a CC double bond on the first carbon atom (-carbon). The index x corresponds to the number of carbon atoms, and x for example is in the range from 2 to 15, preferably 2 to 8, more preferably 2 to 4. Examples of -olefins are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. Accordingly, for example, neither 1,3-butadiene nor 2-butene or styrene are -olefins.

[0047] The at least one APAO has, for example, a softening point in the range from 70 C. to 170 C., preferably from 80 C. to 150 C., and more preferably from 90 C. to 140 C.

[0048] The at least one APAO preferably has a molecular weight Mn in the range of 6000 and 25 000 g/mol.

[0049] One or more APAOs may be used. It is possible, for example, to use two APAOs in the hotmelt adhesive, advantageously in a weight ratio of first APAO to second APAO in the range from 60:40 to 40:60.

[0050] Suitable thermoplastic APAOs are available commercially, examples being Vestoplast703 and Vestoplast792 from Evonik.

[0051] The hotmelt adhesive composition comprises, for example, 40 to 85 wt %, preferably 60 to 80 wt %, of the at least one APAO.

[0052] The hotmelt adhesive composition further comprises at least one hydrocarbon resin having a softening point of at least 80 C., preferably at least 90 C., and more preferably at least 100 C. The at least one hydrocarbon resin has, for example, a softening point in the range from 80 C. to 150 C., preferably from 90 C. to 140 C. or from 100 C. to 130 C. The hydrocarbon resin is more particularly a hydrocarbon resin which is solid at 25 C. Such resins are also referred to as solid resins.

[0053] One or more hydrocarbon resins may be used. The hydrocarbon resin may be, for example, a petroleum resin, a coal tar resin or a polyterpene resin, each of which may optionally have been modified.

[0054] The hydrocarbon resin may be, for example, an aliphatic, aromatic or cyclic hydrocarbon resin. It may also be a modified hydrocarbon resin, as for example a partially or fully hydrogenated aromatic hydrocarbon resin or an aromatically modified hydrocarbon resin; an aliphatic hydrocarbon resin is preferred.

[0055] The hydrocarbon resin is preferably a C5-C9 hydrocarbon resin, very preferably an aliphatic C5-C9 hydrocarbon resin.

[0056] Suitable hydrocarbon resins are available commercially, examples being HikorezA-2115, HikorezA-1100, and SukorezSU-400, all from Kolon Industries, Inc, Korea, RegaliteR 7100 from Eastman Chemical Co., USA, Escorez1401 from Exxon Mobil, USA, and also Wingtackextra and Wingtack86, each from Cray Valley USA, more particularly a mixture thereof, in a ratio of Wingtackextra to Wingtack86 of, for example, around 60 wt % to around 40 wt %. Aliphatic hydrocarbon resins such as HikorezA-2115 are particularly preferred. The hydrocarbon resin gives the adhesive tack on heating.

[0057] The hotmelt adhesive composition comprises, for example, 5 to 30 wt %, preferably 10 to 20 wt %, of the at least one hydrocarbon resin. Amounts in the range from around 13 to 18 wt % have proven particularly preferable.

[0058] The hotmelt adhesive composition furthermore comprises one or more maleic anhydride-grafted waxes having a softening point of not more than 150 C., which is a maleic anhydride-grafted polypropylene wax or a maleic anhydride-grafted polyethylene wax, with the fraction of the at least one maleic anhydride-grafted wax in the hotmelt adhesive composition being at least 3 wt %. The fraction of the at least one maleic anhydride-grafted wax in the hotmelt adhesive composition is preferably at least 4 wt %, more preferably at least 5 wt %, and very preferably at least 7 wt %.

[0059] The at least one maleic anhydride-grafted wax preferably has a softening point in the 100 C. to 150 C. range, preferably from 120 C. to 150 C.

[0060] The maleic anhydride-grafted wax is a polar-modified polyolefin wax. With particular preference the maleic anhydride grafted wax is a maleic anhydride grafted polypropylene wax.

[0061] The maleic anhydride-grafted wax may be formed, for example, by grafting maleic anhydride onto a polyolefin wax selected from a polypropylene wax or a polyethylene wax. In the case of the polypropylene wax, the wax may be a homopolymer of propylene or a copolymer of propylene. In the case of a polyethylene wax, the wax may be a homopolymer of ethylene or a copolymer of ethylene. The comonomer or comonomers for the propylene copolymer may be, for example, at least one monomer selected from ethylene and olefins, more particularly 1-olefins, having at least 4 carbon atoms, as for example 4 to 12 carbon atoms. The comonomer or comonomers for the ethylene copolymer may be, for example, at least one monomer selected from propylene and olefins, more particularly 1-olefins, having at least 4 carbon atoms, as for example 4 to 12 carbon atoms.

[0062] Suitable polyolefin waxes as a basis for the preparation of the maleic anhydride-grafted waxes may be prepared by thermal degradation of branched or unbranched polyolefin plastics or by direct polymerization of olefins. Examples of suitable polymerization processes include radical processes, where the ethylene or propylene is reacted at high pressures and temperatures to form waxes with a greater or lesser degree of branching; in addition there are processes in which ethylene and/or higher 1-olefins such as propylene are polymerized to unbranched or branched waxes with the aid of organometallic catalysts, examples being Ziegler-Natta catalysts or metallocene catalysts.

[0063] Preferred waxes are polypropylene waxes or polyethylene waxes which are prepared by Ziegler or metallocene catalysis.

[0064] The degree of grafting of the maleic anhydride-grafted wax is, for example, at least 1 wt %, preferably at least 2 wt %, and more particularly at least 3 wt %, of maleic anhydride, based on the weight of the unmodified wax. This degree of grafting is situated preferably in the range from 1 to 15 wt %, more preferably from 3 to 15 wt %, most preferably from 4 to 12 wt %.

[0065] The maleic anhydride-grafted wax has a melt viscosity at 170 C., for example, in the range from 10 to 10 000 mPa.Math.s, more particularly 400 to 3000 mPa.Math.s.

[0066] The hotmelt adhesive composition comprises, for example, 3 to 20 wt %, preferably 4 to 18 wt %, more preferably 5 to 15 wt %, of the at least one maleic anhydride-grafted wax. Amounts in the range from around 7 to 13 wt % have proven particularly preferable. The maleic anhydride-grafted wax improves the adhesion properties of the hotmelt adhesive.

[0067] Suitable maleic anhydride-grafted waxes are available commercially, an example being LicocenePP MA 6452 from Clariant, a maleic anhydride-grafted polypropylene having a maleic anhydride fraction of 7 wt %.

[0068] The hotmelt adhesive composition may optionally comprise further constituents of the kind customary for hotmelts, as for example at least one oil, at least one further thermoplastic polymer and/or at least one additive.

[0069] The oil may be any oil customary for hotmelts. Using oils, however, brings disadvantages in terms of the adhesion. Preferably, therefore, the hotmelt adhesive contains no oil.

[0070] The hotmelt adhesive composition optionally comprises one or more further thermoplastic polymers, preferably nonreactive thermoplastic polymers. By a further thermoplastic polymer here are meant thermoplastic polymers which differ from the atactic poly--olefins, hydrocarbon resins, and maleic anhydride-grafted waxes as defined above.

[0071] Examples of a further thermoplastic polymer are homopolymers or copolymers of unsaturated monomers, more particularly from the group encompassing ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate, higher esters thereof, and (meth)acrylate. Particularly suitable are ethylene-vinyl acetate copolymer (EVA), polypropylene (PP) and polyethylene (PE) as homopolymers.

[0072] The fraction of these further thermoplastic polymers, if used at all, ought not to be too greatfor example less than 5 wt %, preferably less than 2 wt %, preferably less than 1 wt %, based on the weight of the hotmelt adhesive composition. More particularly, the fraction of polypropylene, if used, ought to be less than 2 wt %, preferably less than 1 wt %, based on the weight of the hotmelt adhesive. In one preferred embodiment the hotmelt adhesive composition contains substantially no further thermoplastic polymers, i.e., less than 0.5 wt %, preferably less than 0.1 wt %.

[0073] The hotmelt adhesive composition may optionally comprise one or more additives, selected for example from fillers, plasticizers, adhesion promoters, UV absorbers, UV stabilizers, antioxidants, heat stabilizers, optical brighteners, fungicides, pigments, dyes, and siccatives.

[0074] The total weight of components a), b), and c), i.e., the atactic poly--olefins solid at 25 C.; the hydrocarbon resins with a softening point of at least 80 C.; and the maleic anhydride-grafted wax with a softening point of not more than 150 C., as defined above, based on the weight of the hotmelt adhesive composition, is preferably at least 60 wt %, more preferably at least 80 wt %, even more preferably 95 wt %, and with particular preference at least 98 wt %.

[0075] The hotmelt adhesive composition may be produced by mixing the components in a customary way known to the person skilled in the art for hotmelt adhesives.

[0076] The hotmelt adhesive composition of the invention preferably has a melting or softening point in the range from 100 to 160 C., more particularly from 110 to 140 C.

[0077] The hotmelt adhesive composition of the invention is stable on storage and is readily workable under the customary application conditions, more particularly in the temperature range from 100 to 200 C., and its viscosity is stable for a sufficiently long time, even in the case of application via open rolls. After setting or crystallization, it possesses a relatively high ultimate strength and heat resistance, and also effective resistance to all environmental effects.

[0078] The hotmelt adhesive of the invention in particular has a low reactivation temperature in combination with high heat stability. The adhesion of the applied adhesive to the surfaces of the laminating tool is low.

[0079] The hotmelt adhesive composition of the invention is suitable for all adhesive bonds which can be performed using hotmelt adhesives. The hotmelt adhesive composition of the invention is especially suitable as an adhesive for foil lamination, preferably by vacuum forming lamination or IMG lamination.

[0080] In vacuum forming lamination, an adhesive, in this case the hotmelt adhesive composition of the invention, is first applied to one side of a foila TPO foil, for example. The side in question may be, for example, the reverse of a decorative foil. This is followed by the actual forming lamination. The foil with the adhesive applied thereon is heated and is drawn by vacuum onto a substrate component, based for example on PP, resin-bound natural fibers, or ABS. In this operation, the melted hotmelt adhesive comes into contact with the substrate component for lamination. This is commonly accomplished by application of a vacuum to the substrate component, which is provided with holes, on the side of the substrate component that is opposite the side to be laminated.

[0081] IMG lamination (in-mold graining lamination) is a special instance of vacuum forming lamination, in which the smooth foil also receives its typical grain during the laminating operation described; the smooth foil is preferably a smooth TPO foil. For this purpose, the smooth foil is heated up to around 220 C. At this temperature, the foil is stretchable and it is possible to provide it with the appropriate grain. The first step in the IMG operation is to provide the foil, more particularly TPO foil, with the grain. In the 2.sup.nd step, vacuum is used to apply the heated and adhesive-precoated foil onto the solid substrate.

[0082] The hotmelt adhesive composition of the invention is suitable with preference for vehicle construction, more particularly for automobile construction, as an adhesive, for example, in the lamination of foils, such as TPO foils, for example, onto nonpolar materials, such as polypropylene or natural-fiber substrate materials, for example, or onto polar substrates such as ABS, for example.

[0083] The statements below relating to the method of the invention for foil lamination do of course also apply to a particular degree to the uses identified above, and vice versa.

[0084] A further aspect of the invention relates to a method for producing an assembly composed of a substrate element and a foil by adhesive bonding, said method comprising the following steps: [0085] a) the applying of a hotmelt adhesive composition of the invention to one side of a foil, preferably a polyolefin foil; [0086] b) the heating of the foil coated with the hotmelt adhesive composition, for reactivating, and [0087] c) the drawing of the reactivated foil, coated with the hotmelt adhesive composition, onto the substrate element, with the hotmelt adhesive composition coming into contact with the substrate element and, after cooling, producing the bonded assembly.

[0088] The foil is preferably a decorative foil. The foil is preferably a polyolefin foil and more particularly a TPO foil, in other words a foil based on a thermoplastic, olefin-based elastomer. Foils of this kind are available commercially in great diversity.

[0089] The foil, more particularly the polyolefin foil or TPO foil, may have a thickness, for example, of 0.05 mm to 5 mm, preferably 0.05 to 1 mm. It may have a single-layer or multilayer construction. It is clear to the person skilled in the art that foils, in addition to the polymeric base material, may also comprise other adjuvants and processing agents as well, such as further polymers or additives.

[0090] The substrate element is preferably a three-dimensionally shaped body. The material of the substrate element, or the surface of the substrate material that is to be laminated, may be any desired material, being made for example of plastic, especially polyolefins or ABS, metal, painted metal, wood, woodbase materials, or natural or synthetic fiber materials.

[0091] Examples of plastics materials are materials of polyethylene such as high-density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), including glass fiber-reinforced PP, polyvinyl chloride (PVC), polycarbonate (PC), glass fiber-reinforced plastic (GRP), polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene (ABS), polyamide (PA), and combinations thereof.

[0092] Suitable fiber material comprises natural or synthetic fiber materials, as for example materials composed of natural fibers of cellulose, cotton or protein, or of synthetic fibers of polyester, homopolymers or copolymers of ethylene and/or propylene, or viscose, or mixtures thereof. The fiber material may be, for example, a woven, laid or knitted fabric, preference being given to a felt or nonwoven.

[0093] The substrate element, or the surface of the substrate element that is for lamination, is preferably made of a material of polypropylene, natural fiber, e.g., a resin-bound natural fiber, or ABS. The polypropylene is preferably glass fiber-reinforced polypropylene.

[0094] Where necessary, the surface of the substrate element that is to be laminated may have been pretreated, by cleaning and/or by application of a primer, for example. In general, however, there is no need for application of a primer.

[0095] The hotmelt adhesive composition can be applied to the foil in a customary way. For example, the hotmelt adhesive composition is liquefied by heating and can be applied to the foil by customary coating techniques, such as brushing or rolling, for example.

[0096] The application temperature is typically in the range from 150 to 200 C., more particularly 160 to 180 C. At this temperature the adhesive is readily workable. The viscosity of the hotmelt adhesive compositions can be adapted to the application temperature.

[0097] Cooling produces the foil coated with the hotmelt adhesive composition. The layer thickness of the hotmelt adhesive layer is customarily relatively thin; the applied amount is situated, for example, in the range from 50 to 150 g/m.sup.2.

[0098] The foils thus coated are stable on storage and can be stored even for weeks, which is very advantageous for industrial manufacture.

[0099] For the actual production of the assembly, the foil coated with the hotmelt adhesive composition is heated for reactivation of the hotmelt and is then applied or drawn onto the substrate element. The heating temperature for reactivation is typically in the range from 100 to 200 C., more particularly 140 to 180 C. This may take place in any possible way, such as in an oven, by means of hot air, or by IR irradiation, for example.

[0100] Following its reactivation by heating, the film is drawn onto or applied to the substrate element. Drawing-on ought usefully to take place as soon as possible after reactivation, as for example less than 60 s, preferably less than 20 s, after reactivation, in order to prevent excessive cooling of the hotmelt. The process of drawing-on puts the hotmelt adhesive composition in contact with the substrate element, so producing the adhesive bond between foil and substrate element by means of the hotmelt, after cooling.

[0101] The foil is commonly drawn on by pressure by means of presses or, preferably, by application of vacuum. The foil is drawn onto the substrate element preferably by vacuum forming lamination or IMG lamination. These processes have already been explained above.

[0102] The invention also relates to the assembly obtainable by the method described. The assembly is preferably an article of industrial manufacture, more particularly a component of a vehicle, preferably of an automobile.

EXAMPLES

[0103] The following raw materials were used for producing hotmelt adhesives. All of the stated softening points are determined according to DIN EN 1238, apart from that for the PP homopolymer HE40XI, which was determined as a Vicat softening temperature.

TABLE-US-00001 Escorez1401 HC resin, softening point 119 C. Exxon Mobil, USA RegaliteR 7100 HC resin, softening point 102 C. Eastman Chemical Co., USA HikorezA-2115 HC resin, softening point 112 C. Kolon Industries, Inc, Korea Vestoplast703 Amorphous or atactic poly-alpha- Evonik, olefin, softening point 124 C. Germany Vestoplast792 Amorphous or atactic poly-alpha- Evonik, olefin, softening point 108 C. Germany Vestoplast608 Amorphous or atactic poly-alpha- Evonik, olefin, softening point 157 C. Germany Polypropylene Polypropylene homopolymer, Polychim homopolymer softening point 154 C. Industrie, HE40XI France EpoleneE-43 Maleic anhydride grafted poly- Westlake propylene, softening point 158 C. Chemical, USA LicocenePP Maleic anhydride grafted poly- Clariant, MA 6452 propylene, softening point 143 C. Switzerland LicocenePP Polypropylene wax, softening Clariant, 6102 point 145 C. Switzerland TinopalOB Optical brightener BASF, Germany Irganox1010 Antioxidant/stabilizer BASF, Germany

[0104] Six hotmelt adhesive compositions (inventive examples 1 and 2 and comparative examples 1 to 4) were produced by combining the ingredients with one another in accordance with the parts by weight indicated in table 1 under reduced pressure in a stirrer at a temperature of 190 C.

[0105] The hotmelt adhesives produced were investigated for their properties by the methods set out below. The results are given in table 2.

Adhesion to Substrates

[0106] An investigation was conducted into the substrates to which the hotmelt adhesives adhere. The substrates investigated were made of polypropylene (PP), polyvinyl chloride (PVC), polyamide (PA), polycarbonate (PC), glass fiber-reinforced plastic (GRP), and polymethyl methacrylate (PMMA). The table recites the substrates to which the hotmelt adhered.

Viscosity

[0107] The adhesive is melted in a sealed tube at 200 C. in a heating cabinet for 20 minutes. 9.7 mg of adhesive are weighed out into a disposable sleeve and conditioned in a viscometer at the start temperature for 20 minutes; the viscosity is measured at 1, 2.5, 5, and 10 rpm; a note is made of the value established after 5 minutes of measurement; conditioning for 20 minutes takes place on each temperature increase (spindle #27, Brookfield viscometer).

Open Time

[0108] The open time is the maximum time between application of adhesive and bonding of the substrates, and is determined as follows: [0109] The adhesive is melted in a sealed tube at 200 C. in a heating cabinet for 20 minutes [0110] The adhesive is introduced into a 500p applicator on a hotplate at 200 C.; a film of adhesive is drawn down onto dried silicone paper (drawdown length about 30 cm) [0111] Preparation of a number of silicone paper strips (10010 mm) [0112] The film is taken from the hotplate and placed on a bench conditioned at room temperature (23 C.), and the clock is started [0113] Approximately every 5 seconds, a paper strip is pressed gently by its nonsiliconized side onto the adhesive, using the finger, and slowly withdrawn again [0114] When the paper strip can be separated from the film of adhesive without sticking to it or without tearing, the clock is stopped and the time which has elapsed is recorded.

Initial Strength

[0115] The adhesive is melted in a sealed tube at 200 C. in a heating cabinet for 20 minutes [0116] The adhesive is applied to one side of the PP test body; it is pressed by gentle pressure onto the other test body, and the bond is fixed with a weight of 500 g [0117] Test bodies used for this measurement are PP test bodies (100 mm25 mm*4 mm); the area to be bonded is 25 mm25 mm, adhesive thickness 1 mm [0118] Measurements are made of the initial strength (N/mm.sup.2) after 3, 6, 10, 20, and 30 minutes [0119] Only the 30-minute value is recorded in the evaluation of the results.

Shore A

[0120] The Shore A is measured according to DIN EN ISO 868.

Softening Point

[0121] The softening point was measured by the ring & ball method, DIN EN 1238.

Heat Stability

[0122] The adhesive is melted in a sealed tube at 200 C. in a heating cabinet for 20 minutes [0123] The adhesive is applied to one side of the PP test body; it is pressed by gentle pressure onto the other test body, and the bond is fixed with a weight of 500 g; a triplicate determination is carried out [0124] Test bodies used for this measurement are PP test bodies (100 mm25 mm*4 mm); the area to be bonded is 25 mm25 mm, adhesive thickness 1 mm [0125] After 24 hours, the specimens are hung in a heating cabinet and the bond is loaded with a weight of 1 kg. The heating cabinet is conditioned to 40 C. beforehand. After each hour, the temperature is raised by 10K. The temperature at which the bond failed is read off [0126] The heated stability is then the recorded temperature at which the bond was still intact (for example, if the bond fails at 140 C., the heat stability reported is 130 C.)

TABLE-US-00002 TABLE 1 (all figures in parts by weight) Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Inv. Ex. 1 Inv. Ex. 2 Ex. 3 Ex. 4 Escorez1401 15.14 RegaliteR 7100 40.75 16.27 16.41 16.22 HikorezA-2115 16.13 Vestoplast703 34.85 36.88 37.96 38.29 36.76 Vestoplast792 34.85 32.00 37.31 40.13 42.67 37.84 Vestoplast608 27.00 Polypropylene 5.77 homopolymer HE40XI EpoleneE-43 9.13 LicocenePP MA 9.46 5.42 2.41 6452 LicocenePP 8.97 6102 TinopalOB 0.02 Irganox1010 0.24 0.25 0.22 0.22 0.22 0.22 100.00 100.00 100.00 100.00 100.00 100.01

TABLE-US-00003 TABLE 2 Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Inv. Ex. 1 Inv. Ex. 2 Ex. 3 Ex. 4 Adhesion to PP, PVC, PP PP, PVC, PP, PVC, PP PP substrate PA, PMMA PA, PC, PC, GRP, GRP, PMMA PMMA Viscosity @ 180 C. 29 500 15 000 15 000 17 500 21 500 13 000 [mPa * s] Open time, 500 m 25 30 30 40 40 35 at 200 C. [sec.] Initial strength 2.5 0.6 2.0 1.5 1.3 1.8 [N/mm.sup.2] Shore A 80 52 80 75 73 78 Softening point 157 130 130 124 127 127 (Ring Ball) [ C.] Heat stability PP- 110 60 100 90 90 100 PP [ C.]

Adhesion to ABS

[0127] The adhesion of the hotmelt adhesives to ABS substrates was investigated, by laminating a TPO foil coated with the hotmelt adhesive onto an ABS substrate at various laminating temperatures (140 C. and 200 C.). The experiments at 200 C. served for testing, but in practice a laminating temperature of 200 C. is too high and is not operationally suitable. The assemblies produced were evaluated, 24 hours after production, visually and by means of a manual peel test. The results are shown in table 3.

TABLE-US-00004 TABLE 3 Adhesion to ABS laminated @ Comp. Ex. 1 Comp. Ex. 2 Inv. Ex. 1 Inv. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 140 C. adhesive good good good poor adhesion poor adhesion failure to the adhesion, adhesion, adhesion, to ABS to ABS ABS foam pullout foam pullout foam pullout TPO foil TPO foil TPO foil 200 C. good good good good poor adhesion poor adhesion adhesion, adhesion, adhesion, adhesion, to ABS to ABS foam pullout foam pullout foam pullout foam pullout TPO foil TPO foil TPO foil TPO foil

Evaluation of the Reactivation Behavior of Precoated TPO Foils

[0128] For inventive example 1 and comparative example 1, a laminating operation with different waiting times between reactivation and pressing was simulated. Evaluation was made visually and with a manual peel test. Materials used were as follows:

TABLE-US-00005 Foil TPO foil without primer Substrate Polypropylene (PP GF 30: PP with 30% glass fiber) Hotmelts Inventive example 1 and comparative example 1

Production of Assemblies

[0129] The adhesive was applied in each case at 80 g/m.sup.2 to the TPO foil at 200 C. in the case of comparative example 1 or at 170 C. in the case of inventive example 1. Cooling gave the foil coated with adhesive. The applied adhesive was reactivated using IR. After a waiting time x, the reactivated TPO foil was placed onto PP and rolled on using a 5 kg roller. Cooling (around 5-10 min) was followed by the peel test. The results for the test with the hotmelt of inventive example 1 are shown in table 4, and the results for the test with the hotmelt of comparative example 1 are shown in table 5.

Evaluation:

[0130] sat. satisfactory=foam pullout, foil
unsat. unsatisfactory=adhesive failure to the PP

TABLE-US-00006 TABLE 4 Assembly with hotmelt from inventive example 1 Reactivation Waiting time after reactivation for pressing temperature immediate 6 s 10 s 12 s 15 s 20 s 170 C. sat. sat. sat. sat. sat. sat. 160 C. sat. sat. sat. sat. sat. sat. 150 C. sat. sat. sat. sat. sat. sat. 140 C. sat. sat. sat.* sat.* unsat. unsat. *partial foam pullout, foil + adhesive failure to the PP

TABLE-US-00007 TABLE 5 Assembly with hotmelt from comparative example 1 Reactivation Waiting time after reactivation for pressing temperature immediate 6 s 10 s 12 s 15 s 20 s 200 C. sat. sat. sat. sat. sat. unsat. 190 C. sat. sat. sat.* sat.* sat.* unsat. 180 C. sat. sat. sat.* sat.* unsat. unsat. 170 C. sat. sat.* unsat. unsat. unsat. unsat. *partial foam pullout, foil + adhesive failure to the PP