Advanced adhesive

Abstract

The invention provides an adhesive particularly suitable for bonding metals to castable polyurethanes, polyesters and / or polyamides.

Description

Technical Field

[0001] This invention relates to the field of one-component adhesives, particularly for the adhesion of polyurethane, polyester and / or nylon to metals. Background Technology

[0002] Cast polyurethane is an economical, efficient, and reliable elastomer that combines some of the performance advantages of engineering plastics, metals, and ceramics with the resilience and flexibility of rubber. Cast polyurethane is well-known for its high load-bearing capacity, high impact strength, high abrasion resistance, high resilience, and excellent oil and grease resistance. Polyurethane is typically chosen when resistance to slip, tension, load-bearing, impact, cutting and tearing, compression, torsional forces, aging effects, and oil resistance is involved.

[0003] Bonding castable polyurethane elastomers to substrates such as metals or plastics places high demands on the adhesive. The adhesive should exhibit properties similar to polyurethane, particularly good heat resistance. A major challenge in cast polyurethane / substrate parts and their bond lines is high-temperature resistance.

[0004] Lightweight design is one of the key technologies for reducing vehicle energy consumption. Replacing traditional materials with plastic polymers has become commonplace in many fields. The automotive, aerospace, industrial, and household machinery industries have consistently benefited from the advantages of lighter, higher-performing components manufactured using efficient and economical processes. Metal substitution is often key to reducing weight, cost, and production time. Substrates like metals or plastic polymers are physically rigid, exhibiting high tensile strength in combination with relatively low fracture strain values.

[0005] The inherent corrosion resistance of polyamides is a strong driving force for replacing metals with glass fiber reinforced polyamides. Hybrid systems of metals and plastics are desirable for flexible part design and parallel performance enhancement. This requires suitable adhesive solutions.

[0006] There is a continued need for adhesives capable of bonding cast polyurethane elastomers to substrates and reinforcing plastics (such as polyesters and polyamides) to metals. In particular, such adhesives with good high-temperature resistance are needed. Summary of the Invention

[0007] In a first aspect, the present invention provides an adhesive comprising:

[0008] (1) Form-1 phenolic resin;

[0009] (2) Polyvinyl butyral;

[0010] (3) A solvent or solvent mixture that can solvate components (1) and (2) while having sufficient volatility to be removed at atmospheric pressure.

[0011] In a second aspect, the present invention provides a method for adhering a first substrate made of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the following steps:

[0012] (1) Providing an assembly comprising a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, and a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, wherein a layer comprising an adhesive comprising: (i) a methylphenolic resin, (ii) polyvinyl butyral, and a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure; and

[0013] (2) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0014] The first and second substrates are not both metals.

[0015] In a third aspect, the present invention provides a method for adhering a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the following steps:

[0016] (1) Provide a first substrate;

[0017] (2) Apply a layer of adhesive to the surface of a first substrate. The adhesive comprises a phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the phenolic resin and polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure.

[0018] (3) Optionally remove the solvent or solvent mixture by evaporation;

[0019] (4) Contact the adhesive layer with a second substrate made of a material selected from polyurethane, polyester, polyamide and metal to form an assembly;

[0020] (5) Heating the component to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0021] The first and second substrates are not both metals.

[0022] In a fourth aspect, the present invention provides a metal substrate coated with an adhesive, wherein the adhesive comprises:

[0023] (1) Form-1 phenolic resin;

[0024] (2) Polyvinyl butyral;

[0025] (3) A solvent or solvent mixture that can solvate components (1) and (2) while having sufficient volatility to be removed at atmospheric pressure.

[0026] In a fifth aspect, the present invention provides a method for adhering a first substrate, which is substantially metal, to a second substrate, which is substantially made of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the following steps:

[0027] (1) Provide a first substrate for metal coated on a surface using an adhesive, the adhesive comprising: (i) a methyl phenolic resin, (ii) polyvinyl butyral, and a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure.

[0028] (2) The coated surface of the first substrate is brought into contact with a second substrate selected from castable polyurethane and polyamide;

[0029] (3) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0030] In a sixth aspect, the present invention provides a method for adhering a first substrate made substantially of a material selected from metals to a second substrate made substantially of a material selected from polyamides, the method comprising the steps of:

[0031] (1) Provide a first metal substrate;

[0032] (2) Apply a layer of adhesive to the surface of a first substrate. The adhesive comprises a phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the phenolic resin and polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure.

[0033] (3) Optionally remove the solvent or solvent mixture by evaporation;

[0034] (4) Apply molten polyamide to the adhesive, so that the heat of the molten polyamide cures the adhesive. Detailed Implementation

[0035] The inventors unexpectedly discovered an adhesive containing the following:

[0036] (1) Form-1 phenolic resin;

[0037] (2) Polyvinyl butyral;

[0038] (3) A solvent or solvent mixture that enables the solvation of components (1) and (2) while having sufficient volatility to be removed at atmospheric pressure, providing excellent adhesion between the following substrate pairs:

[0039] Substrate 1 Substrate 2 Metals (e.g., aluminum, steel) Castable polyurethane Metals (e.g., aluminum, steel) polyamide Metals (e.g., aluminum, steel) Polyester Castable polyurethane Castable polyurethane Castable polyurethane polyamide Castable polyurethane Polyester polyamide polyamide polyamide Polyester Polyester Castable polyurethane Polyester Polyester

[0040] Definitions and abbreviations

[0041] PU polyurethane

[0042] TDI (Toluene Diisocyanate)

[0043] SEC size exclusion chromatography

[0044] The molecular weights of polymers reported herein are number-average or weight-average molecular weights in Daltons (Da), as determined by size exclusion chromatography (SEC).

[0045] methyl phenolic resin

[0046] The adhesive of the present invention comprises a methylphenolic resin, which means a polymer made by reacting formaldehyde and phenol using an alkaline catalyst, such that the polymer contains side hydroxymethyl groups.

[0047] In a particularly preferred embodiment, the methyl phenolic resin has the following characteristics:

[0048] According to DIN EN ISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s.

[0049] According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%. According to DIN 16916-02 and DIN EN ISO 11402, the maximum free formaldehyde content is 5%.

[0050] Its specific gravity at 20℃ is 1.26 g / cm³. 3 .

[0051] The adhesive of the present invention preferably contains 5 to 20 wt%, more preferably 7 to 15 wt%, more particularly preferably 8 to 13 wt%, and even more particularly preferably 11-12 wt% of methyl phenolic resin.

[0052] In a particularly preferred embodiment, the methyl phenolic resin is used at 8 to 13 wt%, more particularly preferably 11-12 wt%, and has the following characteristics:

[0053] According to DIN EN ISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s.

[0054] According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%.

[0055] According to DIN 16916-02 and DIN EN ISO 11402, the maximum free formaldehyde content is 5%.

[0056] Its specific gravity at 20℃ is 1.26 g / cm³. 3 .

[0057] Polyvinyl butyral

[0058] The adhesive of the present invention comprises polyvinyl butyral (PVB). In a preferred embodiment, PVB has the following structure:

[0059]

[0060] The polyvinyl acetate (l) content is 1-8 wt%, the polyvinyl alcohol (m) content is 11-27 wt%, and the acetal (p) content is 65-88 wt%.

[0061] Particularly preferred, the acetal has the following structure:

[0062]

[0063] Preferably, the polyvinyl alcohol content is 11-16 wt%. Preferably, the polyvinyl acetate content is 1-6 wt%. Preferably, the acetal content is 82-88 wt%. In a particularly preferred embodiment, the polyvinyl alcohol content is 11-16 wt%, the polyvinyl acetate content is 1-6 wt%, and the acetal content is 82-88 wt%. These weight percentages are based on the total weight of PVB.

[0064] More preferably, the polyvinyl alcohol content is 12-16 wt%. Preferably, the polyvinyl acetate content is 1-4 wt%. Preferably, the acetal content is 82-88 wt%. In a particularly preferred embodiment, the polyvinyl alcohol content is 12-16 wt%, the polyvinyl acetate content is 1-4 wt%, and the acetal content is 82-88 wt%. These weight percentages are based on the total weight of PVB.

[0065] In a particularly preferred embodiment, polyvinyl butyral has a non-volatile content of ≥97.5 wt% (as determined according to DIN 53216), a polyvinyl alcohol content of 12-16 wt% and a polyvinyl acetate content of 1-4 wt%, an acetal content of 82-88 wt%, a dynamic viscosity of 120-280 g / L as determined according to DIN 53015 in a 10% ethanol solution at 20°C, a glass transition temperature of 65°C as determined by DSC according to ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / L as determined according to DIN EN 543. Weight percentages are based on the total weight of PVB.

[0066] The adhesive of the present invention preferably contains 5 to 15 wt% of PVB based on the total weight of the adhesive, more preferably 8 to 12 wt%, and even more particularly preferably 10-11 wt%.

[0067] In a particularly preferred embodiment, PVB is present at 8 to 12 wt% based on the total weight of the adhesive, and the PVB has the following structure:

[0068]

[0069] The polyvinyl acetate (l) content is 1-8 wt%, the polyvinyl alcohol (m) content is 11-27 wt%, and the acetal (p) content is 65-88 wt%, and the acetal has the following structure:

[0070]

[0071] solvent

[0072] The adhesive of the present invention comprises a solvent or solvent mixture capable of solubilizing methyl phenolic resin and polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure. For example, suitable solvents and solvent mixtures are those having a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, and particularly preferably at least 20 hPa.

[0073] Examples of suitable solvent mixtures are those with C 1-6 Alkyl ketones, such as methyl isobutyl ketone, methyl ethyl ketone, and C 1-5 Aliphatic alcohols, as well as benzene and / or mono- and / or di-C 1-3 A mixture of alkylbenzenes.

[0074] Preferably, the solvent mixture contains 50-90 wt% C 1-5 Aliphatic alcohols and 5-20 wt% mono- and / or di-C 1-3 - 2-10 wt% of alkylbenzene mixture with C 1-6Alkyl ketones (e.g., methyl isobutyl ketone, methyl ethyl ketone). These weight percentages are based on the total weight of the solvent mixture.

[0075] For example, a suitable solvent mixture contains methyl isobutyl ketone, alkylbenzenes selected from xylene, toluene, and ethylbenzene, and C... 1-4 Aliphatic alcohols.

[0076] More preferably, it is a mixture of methyl isobutyl ketone, xylene, and isopropanol. Particularly preferably, the solvent mixture comprises 2-10 wt% methyl isobutyl ketone, 5-20 wt% xylene, and 50-90 wt% isopropanol based on the total weight of the solvent mixture.

[0077] A particularly preferred solvent mixture is 5.9 wt% methyl isobutyl ketone, 13.61 wt% xylene, and 80.47 wt% isopropanol based on the total weight of the solvent mixture.

[0078] Other ingredients

[0079] The adhesive of the present invention may additionally contain other components, such as:

[0080] The dye allows for the identification of the area to be applied. The intensity of the dye provides an indication of the film thickness.

[0081] Phenolic varnish resin can improve film-forming properties. If used, the phenolic varnish resin is preferably present at 1-15 wt%, more preferably 2-5 wt%, based on the total weight of the adhesive.

[0082] Manufacturing method

[0083] The adhesive composition of the present invention is prepared by mixing the components until they dissolve.

[0084] How to use

[0085] The adhesive compositions of the present invention are particularly suitable for adhering castable polyurethanes and polyamides to each other, but especially to metals such as aluminum and / or steel.

[0086] This invention provides a method for adhering a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the following steps:

[0087] (1) Provide a first substrate;

[0088] (2) Apply a layer of adhesive to the surface of a first substrate. The adhesive comprises a phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the phenolic resin and polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure.

[0089] (3) Optionally remove the solvent or solvent mixture by evaporation;

[0090] (4) Contact the adhesive layer with a second substrate made of a material selected from polyurethane, polyester, polyamide and metal to form an assembly;

[0091] (5) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0092] The following pairs of substrates are particularly preferred:

[0093] Substrate 1 Substrate 2 Metal Castable polyurethane aluminum Castable polyurethane steel Castable polyurethane Metal polyamide aluminum polyamide steel polyamide Metal Polyamide 66 aluminum Polyamide 66 steel Polyamide 66 Castable polyurethane Castable polyurethane Castable polyurethane polyamide polyamide polyamide

[0094] Before applying the adhesive of the present invention, the metal substrate may be treated. For example, the metal surface may be cleaned using an aqueous detergent solution and / or an organic solvent to remove dirt and / or oil and / or grease. The metal surface may also be sandblasted.

[0095] Castable polyurethane is typically formulated immediately before use and remains in a flowable form for a limited time. Flowable polyurethane can be applied to another substrate by pouring or other means.

[0096] Polyamides are typically in solid form and are produced by injection molding, blow molding, or extrusion. Alternatively, polyamides can be applied to adhesive-coated substrates in melt form, particularly by injection molding.

[0097] An adhesive is applied to one or two substrates. Typically, one substrate (e.g., metal) is rigid, and the second substrate is fluid when the adhesive bond is formed, such as molten plastic (e.g., molten polyester or polyamide) or a plastic that has not been sufficiently cured to be in a fluid state (e.g., castable polyurethane). In such cases, the adhesive is applied to the rigid substrate, and the fluid plastic is applied to the adhesive.

[0098] In one embodiment, an adhesive is applied to a metal substrate, and a castable polyurethane is applied thereon.

[0099] In the second embodiment, an adhesive is applied to a metal substrate, the substrate is placed in a mold, and polyamide is injected onto the adhesive-coated surface.

[0100] In the third embodiment, an adhesive is applied to a metal substrate, the substrate is placed in a mold, and polyester is injected onto the adhesive-coated surface.

[0101] Typically, the adhesive is applied to a thickness of 20-120 micrometers, more preferably between 20-80 micrometers or 20-60 micrometers. The optimal thickness will depend on the surface roughness. Adhesion is generally affected when the thickness is below 20 micrometers. Adhesive failure can be observed under impact or excessive load when the thickness exceeds 120 micrometers.

[0102] The adhesive can be applied, for example, by spraying, brushing, applying with a cloth, impregnation, or printing processes (including the use of stencils). In a preferred embodiment, the adhesive is preferably applied to the metal substrate by spraying and brushing.

[0103] After application, the solvent or solvent mixture can be evaporated simply by placing the substrate under ambient conditions. If desired, evaporation can be accelerated by blowing air across the surface and / or exposing the substrate to a vacuum.

[0104] In some cases, the adhesive of the present invention can be applied to a substrate, the solvent evaporated, and the substrate coated with the adhesive can be stored for later use or transferred to another assembler who can then use it for bonding to a second substrate. Ideally, bonding to the second substrate takes place within 6 to 8 weeks of applying the adhesive.

[0105] The adhesive is cured by heating from 90°C to 200°C. Heating can occur, for example, in an oven by IR, convection, or radiation heating. The curing temperature must not exceed the melting temperature of the substrate. For polyurethane, the preferred temperature is 90°C to 130°C, more preferably 90°C to 110°C. For polyamide, the preferred temperature range is 100°C to 160°C.

[0106] When molten polymers, such as polyamides, are applied directly to the adhesive, no additional curing is required, as the heat from the molten polymer is sufficient to cure the adhesive.

[0107] Curing time will depend on the substrate and bonding conditions. For example, when bonding castable polyurethane, the curing time is typically 12-20 hours, more often 16 hours. When bonding polyamide, the curing time is typically 16-72 hours, more preferably 24-72 hours. When bonding polyester, the curing time is typically 16-72 hours, more preferably 24-72 hours.

[0108] When a polymer, such as polyamide, is applied directly to an adhesive, curing occurs within minutes, such as 5-10 minutes.

[0109] In a preferred embodiment, solid polyamide is bonded, particularly to metal, and cured at 100°C-160°C for 24 to 72 hours.

[0110] In another preferred embodiment, castable polyurethane is bonded, particularly to metal, and cured at 90°C-110°C for 12-24 hours, more preferably 16 hours.

[0111] In another preferred embodiment, molten polyamide is applied to a substrate coated with an adhesive, particularly a metal substrate, and curing is achieved by the heat of the molten polyamide.

[0112] Particularly preferred embodiments

[0113] The following are particularly preferred embodiments of the adhesive composition of the present invention:

[0114] 1. A method for adhering a first substrate made of castable polyurethane to a second substrate made of metal, the method comprising the steps of:

[0115] (1) Providing an assembly comprising a first substrate made substantially of castable polyurethane and a second substrate made substantially of metal, wherein a layer comprising an adhesive comprising: (i) a methylphenolic resin, (ii) polyvinyl butyral, and a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure; and

[0116] (2) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0117] 2. The method as described in Example 1, wherein the heating in step (2) is performed for 12-24 hours, particularly 16 hours.

[0118] 3. A method for adhering a first substrate made of polyamide to a second substrate made of metal, the method comprising the steps of:

[0119] (1) Providing an assembly comprising a first substrate made substantially of polyamide and a second substrate made substantially of metal, wherein a layer comprising an adhesive comprising: (i) a methylphenolic resin, (ii) polyvinyl butyral, and a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure; and

[0120] (2) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0121] 4. The method as described in Example 3, wherein the heating in step (2) is performed for 24-72 hours.

[0122] 5. A method for adhering a first substrate, which is substantially metal, to a second substrate, which is substantially castable polyurethane, the method comprising the steps of:

[0123] (1) Provide the first substrate;

[0124] (2) Apply a layer of adhesive to the surface of the first substrate, the adhesive comprising a methyl phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the methyl phenolic resin and the polyvinyl butyral while having sufficient volatility to be removed in the atmosphere.

[0125] (3) Optionally, the solvent or solvent mixture is removed by evaporation;

[0126] (4) Contact the adhesive layer with a second substrate made of castable polyurethane to form an assembly;

[0127] (5) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0128] 6. The method of claim 5, wherein the heating in step (5) is performed for 12-24 hours, particularly 16 hours.

[0129] 7. A method for adhering a first substrate, which is substantially metal, to a second substrate, which is substantially polyamide, the method comprising the steps of:

[0130] (1) Provide the first substrate;

[0131] (2) Apply a layer of adhesive to the surface of the first substrate, the adhesive comprising a methyl phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the methyl phenolic resin and the polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure.

[0132] (3) Optionally, the solvent or solvent mixture is removed by evaporation;

[0133] (4) Contact the adhesive layer with a second substrate made of polyamide to form an assembly;

[0134] (5) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0135] 8. The method of claim 7, wherein the heating in step (5) is performed for 24-72 hours.

[0136] 9. A method for adhering a first substrate made substantially of a material selected from metals to a second substrate made substantially of a material selected from polyamides, the method comprising the steps of:

[0137] (1) Provide a first metal substrate;

[0138] (2) Apply a layer of adhesive to the surface of the first substrate, the adhesive comprising a methyl phenolic resin, polyvinyl butyral, and a solvent or solvent mixture capable of solubilizing the methyl phenolic resin and the polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure.

[0139] (3) Optionally, the solvent or solvent mixture is removed by evaporation;

[0140] (4) Apply molten polyamide to the adhesive, such that the heat of the molten polyamide causes the adhesive to solidify.

[0141] 10. The method as described in Example 9, wherein the solvent or solvent mixture has a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, and particularly preferably at least 20 hPa.

[0142] 11. The method as described in Examples 9 and / or 10, wherein the polyamide is applied by injection molding.

[0143] 12. A metal substrate coated with an adhesive, wherein the adhesive comprises:

[0144] (1) Form-1 phenolic resin;

[0145] (2) Polyvinyl butyral;

[0146] (3) A solvent or solvent mixture that can solvate components (1) and (2) while having sufficient volatility to be removed at atmospheric pressure.

[0147] 13. A method for adhering a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of:

[0148] (1) Provided as a first substrate of metal coated on a surface with an adhesive, the adhesive comprising: (i) a methyl phenolic resin, (ii) polyvinyl butyral, a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure.

[0149] (2) The coated surface of the first substrate is brought into contact with a second substrate selected from castable polyurethane and polyamide;

[0150] (3) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0151] 14. An adhesive comprising:

[0152] (1) Form-1 phenolic resin;

[0153] (2) Polyvinyl butyral;

[0154] (3) A solvent or solvent mixture capable of solvating components (1) and (2) having a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, and particularly preferably at least 20 hPa.

[0155] 15. A method for adhering a first substrate made of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of:

[0156] (1) Providing an assembly comprising a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, and a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, wherein a layer comprising an adhesive comprising: (i) a methylphenolic resin, (ii) polyvinyl butyral, and a solvent or solvent mixture capable of solvating components (i) and (ii), said solvent or solvent mixture having a vapor pressure of at least 5 hPa, more preferably at least 10 hPa, and particularly preferably at least 20 hPa at 20°C; and

[0157] (2) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0158] The first and second substrates are not both metals.

[0159] 16. A method for adhering a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of:

[0160] (1) Provide the first substrate;

[0161] (2) Apply a layer of adhesive to the surface of the first substrate, the adhesive comprising a methyl phenolic resin, polyvinyl butyral and a solvent or solvent mixture capable of solubilizing the methyl phenolic resin and the polyvinyl butyral, the solvent or solvent mixture having a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, and particularly preferably at least 20 hPa.

[0162] (3) Optionally, the solvent or solvent mixture is removed by evaporation;

[0163] (4) Contact the adhesive layer with a second substrate made of a material selected from polyurethane, polyester, polyamide and metal to form an assembly;

[0164] (5) Heating the component to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0165] The first and second substrates are not both metals.

[0166] 17. A metal substrate coated with an adhesive, wherein the adhesive comprises:

[0167] (1) Form-1 phenolic resin;

[0168] (2) Polyvinyl butyral;

[0169] (3) A solvent or solvent mixture capable of solvating components (1) and (2) having a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, and particularly preferably at least 20 hPa.

[0170] 18. The metal substrate as described in Example 14, wherein the adhesive has a thickness of 20-120 micrometers, more preferably between 20-80 micrometers or 20-60 micrometers.

[0171] 19. A method for adhering a first substrate, which is substantially metal, to a second substrate, which is substantially made of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of:

[0172] (1) Provided as a first substrate of metal coated on a surface with an adhesive, the adhesive comprising: (i) a methyl phenolic resin, (ii) polyvinyl butyral, a solvent or solvent mixture capable of solvating components (i) and (ii), the solvent or solvent mixture having a vapor pressure of at least 5 hPa at 20°C, more preferably at least 10 hPa, particularly preferably at least 20 hPa;

[0173] (2) The coated surface of the first substrate is brought into contact with a second substrate selected from castable polyurethane and polyamide;

[0174] (3) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates.

[0175] 20. Any of the foregoing embodiments, wherein the methyl phenolic resin has the following characteristics:

[0176] According to DIN EN ISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s;

[0177] According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%.

[0178] According to DIN 16916-02 and DIN EN ISO 11402, the maximum free formaldehyde content is 5%.

[0179] Its specific gravity at 20℃ is 1.26 g / cm³. 3 .

[0180] 21. In any of the foregoing embodiments, the adhesive contains 5 to 20 wt%, more preferably 7 to 15 wt%, more particularly preferably 8 to 13 wt%, and even more particularly preferably 11-12 wt% of a methyl phenolic resin based on the total weight of the adhesive.

[0181] 22. Any of the foregoing embodiments, wherein the PVB has the following structure:

[0182]

[0183] Based on the total weight of the PVB, the content of polyvinyl acetate (l) is 1-8 wt%, the content of polyvinyl alcohol (m) is 11-27 wt%, and the content of acetal (p) is 65-88 wt%.

[0184] 23. Example 22, wherein the acetal has the following structure:

[0185]

[0186] 24. Any of the foregoing embodiments, wherein the polyvinyl alcohol content in the PVB is 11-16 wt% based on the total weight of the PVB.

[0187] 25. Any of the foregoing embodiments, wherein the polyvinyl acetate content in the PVB is 1-6 wt% based on the total weight of the PVB.

[0188] 26. Any of the foregoing embodiments, wherein the acetal content in the PVB is 82-88 wt%. In a particularly preferred embodiment, the polyvinyl alcohol content is 11-16 wt%, the polyvinyl acetate content is 1-6 wt%, and the acetal content is 82-88 wt%. These weight percentages are based on the total weight of the PVB.

[0189] 27. Any of the foregoing embodiments, wherein the PVB has a non-volatile content greater than or equal to 97.5 wt% (as determined according to DIN 53216), a polyvinyl alcohol content of 12-16 wt% and a polyvinyl acetate content of 1-4 wt%, an acetal content of 82-88 wt%, a dynamic viscosity of 120-280 as determined according to DIN 53015 in a 10% ethanol solution at 20°C, a glass transition temperature of 65°C as determined by DSC according to ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / L as determined according to DIN EN 543, wherein the weight percentages are based on the total weight of the PVB.

[0190] 28. In any of the foregoing embodiments, the adhesive contains 5 to 15 wt%, more preferably 8 to 12 wt%, and more particularly preferably 10-11 wt% PVB based on the total weight of the adhesive.

[0191] 29. Any of the foregoing embodiments, wherein the solvent is a solvent having C 1-6 Alkyl ketones, such as methyl isobutyl ketone, methyl ethyl ketone, and C 1-5 Aliphatic alcohols and mono- and / or di-C 1-3 A mixture of alkylbenzenes.

[0192] 30. Any of the foregoing embodiments, wherein the solvent mixture comprises 2-10 wt% of a solvent having C 1-6 Alkyl ketones (e.g., methyl isobutyl ketone, methyl ethyl ketone), said ketone with 50-90 wt% C 1-5 Aliphatic alcohols and 5-20 wt% mono- and / or di-C 1-3 - Alkylbenzene mixture, wherein the weight percentage is based on the total weight of the solvent mixture.

[0193] 31. Any of the foregoing embodiments, wherein the solvent mixture comprises methyl isobutyl ketone, an alkylbenzene selected from xylene, toluene, and ethylbenzene, and C 1-4 Aliphatic alcohols.

[0194] 32. In any of the foregoing embodiments, the solvent mixture is a mixture of methyl isobutyl ketone, xylene, and isopropanol.

[0195] 33. In any of the foregoing embodiments, wherein the solvent mixture comprises 2-10 wt% methyl isobutyl ketone, 5-20 wt% xylene and 50-90 wt% isopropanol based on the total weight of the solvent mixture.

[0196] 34. In any of the foregoing embodiments, the solvent mixture comprises 5.9 wt% methyl isobutyl ketone, 13.61 wt% xylene, and 80.47 wt% isopropanol based on the total weight of the solvent mixture.

[0197] 35. Any of the foregoing embodiments, wherein the metal substrate is treated with a detergent aqueous solution and / or an organic solvent to remove dirt and / or oil and / or grease, and / or the metal surface is sandblasted before applying the adhesive of the present invention.

[0198] 36. In any of the foregoing embodiments, the castable polyurethane is typically formulated immediately before use and remains in a flowable form for a limited time. The flowable polyurethane can be applied to another substrate by pouring or other means.

[0199] 37. Any of the foregoing embodiments, wherein, after application, the solvent or solvent mixture is evaporated by placing the substrate under ambient conditions, and / or by blowing air across the surface, and / or by exposing the substrate to a vacuum.

[0200] 38. Any of the foregoing embodiments, wherein the adhesive is applied to a substrate, the solvent is evaporated, and the substrate coated with the adhesive is stored for later use.

[0201] 39. In any of the foregoing embodiments, curing is carried out by heating from 90°C to 200°C, preferably 110°C to 130°C.

[0202] 40. Any of the foregoing embodiments, wherein the adhesive further comprises a phenolic varnish resin.

[0203] 41. In any of the foregoing embodiments, the adhesive further comprises 1-15 wt%, 2-15 wt%, or 2-5 wt% of phenolic varnish resin based on the total weight of the adhesive.

[0204] Example

[0205]

[0206]

[0207] Polyvinyl butyral

[0208] The polyvinyl butyral used has a non-volatile content of ≥97.5 wt% (as determined according to DIN 53216). It has the following structure:

[0209]

[0210] The polyvinyl alcohol (m) content is 12-16 wt% and the polyvinyl acetate (l) content is 1-4 wt%, and the acetal has the following structure:

[0211]

[0212] It has a dynamic viscosity of 120-280, as determined in a 10% ethanol solution at 20°C according to DIN 53015. It has a glass transition temperature of 65°C as determined by DSC according to ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / l as determined according to DIN EN 543.

[0213] adhesive

[0214] Mix the ingredients listed in Table 2 together and stir for 2 hours until all ingredients are dissolved. Ceresrot is used to visually distinguish coated and uncoated parts. Two adhesives commonly used for bonding cast polyurethane and metal (Thixon 409 and Thixon 422) are used for comparison purposes.

[0215]

[0216] substrate

[0217] The adhesive performance is evaluated as follows:

[0218] Samples of bonded parts for peel testing were prepared as follows: Steel strips (DIN ISO 813) with a width of 25 mm ± 0.5 mm and a length of 60 mm ± 1 mm, and a bonding area of ​​25 mm x 25 mm, were cleaned and sandblasted. Adhesive (Example 1) was applied to the metal surface by spraying to obtain an adhesive thickness from approximately 20 μm to 30 μm. The adhesive layer on the metal surface was dried at room temperature for 5 h. The coated steel parts were then pre-baked in an oven at 140 °C for 10 min. Other coated parts were used directly after drying. All prepared coated steel strips were heated at 100 °C for 30 min. The heated coated steel strips were then bonded to a castable polyurethane elastomer at 100 °C for 16 h. For the preparation of castable polyurethane elastomers, toluene diisocyanate (TDI)-terminated polyether prepolymer (87.3 wt%, based on the total weight of the castable polyurethane) and dimethylthiotoluene diamine (12.6 wt%, based on the total weight of the castable polyurethane) were heated separately in an oven at 100°C for 30 min. The two heated materials were mixed together for a maximum of 60 seconds and then poured directly onto the coated metal parts at 100°C.

[0219] The specimen was cooled to room temperature before being stretched to failure.

[0220] According to the peel test procedure described in ASTM Test D429 - Method B, after curing, the bonded parts using the bonding system of the present invention are pulled to failure.

[0221] In the standard peel test for bonding cast polyurethane elastomers to metals, the bonding results for Example 1 and the comparative samples Thixon 409 and Thixon 422 are shown in Table 3. Failure modes are reported as %R, which indicates the percentage of failures occurring in the castable polyurethane or polyamide.

[0222] Example 1 showed a high peel strength of 447 N / cm without additional pre-baking and with a film thickness of 35 μm. Applying an additional 10 min of preheating at 140 °C to the coated metal parts resulted in a significant increase in adhesive strength, reaching up to 509 N / cm, even with a lower film thickness of 23–29 μm. Rubber retention was observed to be as high as 98%.

[0223] Conversely, comparative examples of Thixon 402 and Thixon 422 show bond strengths of 326 and 329 N / cm, respectively, at much higher adhesive thicknesses (200 micrometers).

[0224] The adhesive from Example 1 was used to test further bonding between the reinforced plastic and the metal.

[0225] The adhesive used to bond reinforced plastics to itself and / or to metals is tested according to the lap shear test procedure described in ASTM Test D5868-01 (2014).

[0226] Samples of the bonded parts used for peel testing were prepared as follows: A steel strip (DIN ISO 813) with a width of 25 mm ± 0.5 mm and a length of 60 mm ± 1 mm, and a bonding area of ​​25 mm by 30 mm, was cleaned and sandblasted. Adhesive (Example 1) was applied to the metal surface by spraying to produce a thickness from approximately 20 μm to 30 μm. The adhesive layer on the metal surface was dried at room temperature. Glass-reinforced polyamide 66 (PA66) strips (25 mm ± 0.5 mm wide and 60 mm ± 1 mm long) were cleaned with alcohol and dried at room temperature.

[0227] While applying pressure, the coated steel part is pressed onto the polyamide strip, with an overlap of 25 x 30 mm. The specimen is cured at 120°C for 58 hours. The specimen is then cooled to room temperature before being pulled to failure. After curing, the specimen bonded with the adhesive of this invention is pulled to failure according to the peel test procedure described in ASTM Test D5868-01.

[0228] The lap shear bond strength of PA66 bonded to sandblasted steel using the adhesive in Example 1 is 8.6 N / mm. 2 The shear bond strength of the PA66 lap bonded to sandblasted aluminum using the adhesive of Example 1 is 6.1 N / mm. 2 .

[0229]

Claims

1. An adhesive for bonding castable polyurethane and / or polyamide, comprising: (1) Form-1 phenolic resin; The methyl phenolic resin described therein has the following characteristics: According to DIN EN ISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s; According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%. According to DIN 16916-02 and DIN EN ISO 11402, the maximum free formaldehyde content is 5%. Specific gravity 1.26 g / cm at 20°C 3 ; Furthermore, the adhesive contains 5 to 20 wt% of the methyl phenolic resin based on the total weight of the adhesive; (2) Polyvinyl butyral (PVB); in, The PVB has the following structure: Based on the total weight of the PVB, the polyvinyl acetate content is 1-8 wt%, the polyvinyl alcohol content is 11-27 wt%, and the acetal content is 65-88 wt%. (3) A solvent or solvent mixture that can solvate components (1) and (2) while having sufficient volatility to be removed at atmospheric pressure; wherein the solvent is a mixture of C 1-6 ketones with C 1-5 aliphatic alcohols and mono- and / or di-C 1-3 alkylbenzenes; and wherein the solvent mixture comprises 50-90 wt.-% of C 1-5 aliphatic alcohols and 5-20 wt.-% of mono- and / or di-C 1-3 alkylbenzenes and 2-10 wt.-% of ketones with C 1-6 alkyl groups, wherein the weight percentages are based on the total weight of the solvent mixture.

2. The adhesive as described in claim 1, wherein, The solvent or solvent mixture has a vapor pressure of at least 5 hPA at 20°C.

3. The adhesive as described in claim 1, wherein, The solvent or solvent mixture has a vapor pressure of at least 10 hPA at 20°C.

4. The adhesive as claimed in claim 1, wherein, The solvent or solvent mixture has a vapor pressure of at least 20 hPA at 20°C.

5. The adhesive as claimed in claim 1 or 2, comprising 7 to 15 wt% of a methyl phenolic resin based on the total weight of the adhesive.

6. The adhesive as claimed in claim 1 or 2, wherein it contains 11-12 wt% of methyl phenolic resin based on the total weight of the adhesive.

7. The adhesive as described in claim 1 or 2, wherein, The acetal has the following structure:

8. The adhesive as described in claim 1 or 2, wherein, The PVB has a polyvinyl alcohol content of 11-16 wt%, a polyvinyl acetate content of 1-6 wt%, and an acetal content of 82-88 wt%, wherein the weight percentages are based on the total weight of the PVB.

9. The adhesive as described in claim 1 or 2, wherein, The PVB has a polyvinyl alcohol content of 12-16 wt% and a polyvinyl acetate content of 1-4 wt%, wherein the weight percentages are based on the total weight of the PVB.

10. The adhesive as claimed in claim 1 or 2, wherein, The polyvinyl butyral has a non-volatile content of ≥97.5 wt%, 12-16 wt% polyvinyl alcohol, 1-4 wt% polyvinyl acetate, 82-88 wt% acetal, a dynamic viscosity of 120-280 g / L in 10% ethanol solution at 20°C as determined by DIN 53216, a glass transition temperature of 65°C as determined by DSC as determined by ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / L as determined by DIN EN 543, wherein the weight percentages are based on the total weight of the PVB.

11. The adhesive as claimed in claim 1 or 2, wherein, The solvent mixture comprises methyl isobutyl ketone, an alkyl benzene selected from the group consisting of xylene, toluene and ethyl benzene and C 1-4 aliphatic alcohols.

12. The adhesive as claimed in claim 1 or 2, wherein, The solvent mixture is a mixture of methyl isobutyl ketone, xylene, and isopropanol.

13. The adhesive as claimed in claim 1 or 2, wherein, The solvent mixture comprises 2-10 wt% methyl isobutyl ketone, 5-20 wt% xylene, and 50-90 wt% isopropanol based on the total weight of the solvent mixture.

14. The adhesive as claimed in claim 1 or 2, wherein, The solvent mixture comprises 5.9 wt% methyl isobutyl ketone, 13.61 wt% xylene, and 80.47 wt% isopropanol based on the total weight of the solvent mixture.

15. A method for adhering a first substrate made of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of: (1) Providing an assembly comprising a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, and a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, wherein a layer comprising an adhesive comprising: (i) a methylphenolic resin, (ii) polyvinyl butyral (PVB), and a solvent or solvent mixture capable of solvating components (i) and (ii) while having sufficient volatility to be removed at atmospheric pressure; and (2) The component is heated to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates. The first and second substrates are not both metals; and The methyl phenolic resin described therein has the following characteristics: According to DIN ENISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s; According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%. According to DIN 16916-02 and DIN ENISO 11402, the maximum free formaldehyde content is 5%. Its specific gravity at 20℃ is 1.26 g / cm³. 3 ; Furthermore, the adhesive contains 5 to 20 wt% of the methylphenolic resin based on the total weight of the adhesive; and The PVB described therein has the following structure: Based on the total weight of the PVB, the polyvinyl acetate content is 1-8 wt%, the polyvinyl alcohol content is 11-27 wt%, and the acetal content is 65-88 wt%; and The solvent is a C 1-6 Alkyl ketones and C 1-5 Aliphatic alcohols and mono- and / or di-C 1-3 A mixture of alkylbenzenes; and wherein the solvent mixture comprises 50-90 wt% C 1-5 Aliphatic alcohols and 5-20 wt% mono- and / or di-C 1-3 - 2-10 wt% of alkylbenzene mixture with C 1-6 Alkyl ketones, wherein the weight percentage is based on the total weight of the solvent mixture.

16. The method of claim 15, wherein, The solvent or solvent mixture has a vapor pressure of at least 5 hPA at 20°C.

17. The method of claim 16, wherein, The solvent or solvent mixture has a vapor pressure of at least 10 hPA at 20°C.

18. The method of claim 16, wherein, The solvent or solvent mixture has a vapor pressure of at least 20 hPA at 20°C.

19. The method of claim 15 or 16, wherein, The first substrate is metal and the second substrate is castable polyurethane.

20. The method of claim 15 or 16, wherein, The first substrate is metal and the second substrate is polyamide.

21. The method of claim 15 or 16, wherein, The first substrate is metal and the second substrate is polyester.

22. The method of claim 15 or 16, wherein, The heating in step (2) is carried out for 12 to 24 hours.

23. The method of claim 15 or 16, wherein, The heating in step (2) is carried out for 24 to 72 hours.

24. The method of claim 15 or 16, wherein, The polyamide is applied in a molten form.

25. The method of claim 15 or 16, wherein, The polyamide is applied by injection molding.

26. The method of claim 15 or 16, wherein it contains 7 to 15 wt% of a methyl phenolic resin based on the total weight of the adhesive.

27. The method of claim 15 or 16, wherein it contains 11-12 wt% of a methyl phenolic resin based on the total weight of the adhesive.

28. The method of claim 15 or 16, wherein the acetal has the following structure:

29. The method of claim 15 or 16, wherein, The PVB has a polyvinyl alcohol content of 11-16 wt%, a polyvinyl acetate content of 1-6 wt%, and an acetal content of 82-88 wt%, wherein the weight percentages are based on the total weight of the PVB.

30. The method of claim 15 or 16, wherein, The PVB has a polyvinyl alcohol content of 12-16 wt% and a polyvinyl acetate content of 1-4 wt%, wherein the weight percentages are based on the total weight of the PVB.

31. The method of claim 15 or 16, wherein, The polyvinyl butyral has a non-volatile content of ≥97.5 wt%, 12-16 wt% polyvinyl alcohol, 1-4 wt% polyvinyl acetate, 82-88 wt% acetal, a dynamic viscosity of 120-280 g / L in 10% ethanol solution at 20°C as determined by DIN 53216, a glass transition temperature of 65°C as determined by DSC as determined by ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / L as determined by DIN EN 543, wherein the weight percentages are based on the total weight of the PVB.

32. The method of claim 15 or 16, wherein, The solvent mixture contains methyl isobutyl ketone, alkylbenzenes selected from xylene, toluene, and ethylbenzene, and C... 1-4 Aliphatic alcohols.

33. The method of claim 15 or 16, wherein, The solvent mixture is a mixture of methyl isobutyl ketone, xylene, and isopropanol.

34. The method of claim 15 or 16, wherein, The solvent mixture comprises 2-10 wt% methyl isobutyl ketone, 5-20 wt% xylene, and 50-90 wt% isopropanol based on the total weight of the solvent mixture.

35. The method of claim 15 or 16, wherein, The solvent mixture comprises 5.9 wt% methyl isobutyl ketone, 13.61 wt% xylene, and 80.47 wt% isopropanol based on the total weight of the solvent mixture.

36. A method for adhering a first substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal to a second substrate made substantially of a material selected from polyurethane, polyester, polyamide, and metal, the method comprising the steps of: (1) Provide the first substrate; (2) Apply a layer of adhesive to the surface of the first substrate, the adhesive comprising a methyl phenolic resin, polyvinyl butyral (PVB), and a solvent or solvent mixture capable of solubilizing the methyl phenolic resin and the polyvinyl butyral while having sufficient volatility to be removed at atmospheric pressure. (3) Optionally, the solvent or solvent mixture is removed by evaporation; (4) Contact the adhesive layer with a second substrate made of a material selected from polyurethane, polyester, polyamide and metal to form an assembly; (5) Heating the component to 90°C-200°C for a duration sufficient to form an adhesive bond between the first and second substrates. The first and second substrates are not both metals; and The methyl phenolic resin described therein has the following characteristics: According to DIN ENISO 12058-1, the viscosity at 20°C is 4000±500 mPa·s; According to DIN 16916-02-H1 and ISO 8618, the non-volatile component at 135°C is 79±2%. According to DIN 16916-02 and DIN EN ISO 11402, the maximum free formaldehyde content is 5%. Its specific gravity at 20℃ is 1.26 g / cm³. 3 ; Furthermore, the adhesive contains 5 to 20 wt% of the methylphenolic resin based on the total weight of the adhesive; and The PVB described therein has the following structure: Based on the total weight of the PVB, the polyvinyl acetate content is 1-8 wt%, the polyvinyl alcohol content is 11-27 wt%, and the acetal content is 65-88 wt%; and The solvent is a C 1-6 Alkyl ketones and C 1-5 Aliphatic alcohols and mono- and / or di-C 1-3 A mixture of alkylbenzenes; and wherein the solvent mixture comprises 50-90 wt% C 1-5 Aliphatic alcohols and 5-20 wt% mono- and / or di-C 1-3 - 2-10 wt% of alkylbenzene mixture with C 1-6 Alkyl ketones, wherein the weight percentage is based on the total weight of the solvent mixture.

37. The method of claim 36, wherein it contains 7 to 15 wt% of a methyl phenolic resin based on the total weight of the adhesive.

38. The method of claim 36 or 37, wherein it contains 11-12 wt% of a methyl phenolic resin based on the total weight of the adhesive.

39. The method of claim 36 or 37, wherein, The acetal has the following structure:

40. The method of claim 36 or 37, wherein, The PVB has a polyvinyl alcohol content of 11-16 wt%, a polyvinyl acetate content of 1-6 wt%, and an acetal content of 82-88 wt%, wherein the weight percentages are based on the total weight of the PVB.

41. The method of claim 36 or 37, wherein, The PVB has a polyvinyl alcohol content of 12-16 wt% and a polyvinyl acetate content of 1-4 wt%, wherein the weight percentages are based on the total weight of the PVB.

42. The method of claim 36 or 37, wherein, The polyvinyl butyral has a non-volatile content of ≥97.5 wt%, 12-16 wt% polyvinyl alcohol, 1-4 wt% polyvinyl acetate, 82-88 wt% acetal, a dynamic viscosity of 120-280 g / L in 10% ethanol solution at 20°C as determined by DIN 53216, a glass transition temperature of 65°C as determined by DSC as determined by ISO 11357-1, a water absorption rate of 3-5 wt% after immersion in water at 20°C for 24 hours, and a bulk density of 210 g / L as determined by DIN EN 543, wherein the weight percentages are based on the total weight of the PVB.

43. The method of claim 36 or 37, wherein, The solvent mixture contains methyl isobutyl ketone, alkylbenzenes selected from xylene, toluene, and ethylbenzene, and C... 1-4 Aliphatic alcohols.

44. The method of claim 36 or 37, wherein, The solvent mixture is a mixture of methyl isobutyl ketone, xylene, and isopropanol.

45. The method of claim 36 or 37, wherein, The solvent mixture comprises 2-10 wt% methyl isobutyl ketone, 5-20 wt% xylene, and 50-90 wt% isopropanol based on the total weight of the solvent mixture.

46. ​​The method of claim 36 or 37, wherein, The solvent mixture comprises 5.9 wt% methyl isobutyl ketone, 13.61 wt% xylene, and 80.47 wt% isopropanol based on the total weight of the solvent mixture.

47. The method of claim 36 or 37, wherein, The first substrate is metal and the second substrate is polyurethane.

48. The method of claim 36 or 37, wherein, The first substrate is metal and the second substrate is polyamide.

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