Thermosetting composite surface films applied directly to UV treated thermoplastic surfaces and related composite structures

Abstract

The present disclosure relates to methods for directly adhering epoxy-based surface films and other thermosetting surface films to solid thermoplastic surfaces and structures derived from or derivable from these methods. In some embodiments, the present disclosure also relates to composite structures comprising thermoplastic substrates directly bonded to thermosetting (property) surface films; wherein direct bonding defines an interface between a thermoplastic surface of the thermoplastic substrate and a first surface of the thermosetting (property) surface film.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] none. Technical Field

[0003] The present disclosure relates to methods of directly adhering epoxy-based and other thermoset surface films to solid thermoplastic surfaces and structures derived or derivable from these methods. Background Art

[0004] Fiber reinforced polymer matrix composites are high performance structural materials that are commonly used in aircraft components, high performance automobiles, boat hulls and bicycle frames due to their resistance to corrosive environments, their high specific strength or high strength to density ratio and their low weight.

[0005] Conventional composite structures used in the aerospace industry generally include surface films, to provide required performance characteristics for composite structures before painting.Surface films, such as epoxy films, are generally applied to the outer surface of polymer composite products to provide composite materials with surface quality required for aerospace applications.For example, surface films can be co-cured with prepreg to provide a substantially non-porous surface for protection, wherein the resistivity of the surface films is less than the following substrate to reduce the labor, time and cost of composite material manufacturing simultaneously.In addition, these surface films can be functionalized, for example to improve their tolerance to lightning strikes, electrostatic discharges and electromagnetic discharges.

[0006] However, it is not always possible to co-cure or otherwise bond these surface films with structural elements of polymer matrix composites during the manufacture of structural components. Some structural elements are not made of cured composite materials, which makes such bonding with these materials particularly challenging because the intermingling process that occurs during bonding is not possible due to the very high melting points of thermoplastic materials used in aerospace applications.

[0007] In the adhesive industry, it is also known that certain substrates, such as certain high-performance plastics, are difficult to bond. Thermoplastics, such as PEEK (polyetheretherketone); PPS (polyphenylene sulfide); polyaramid (PARA) or polyetherimide (PEI) are attractive structural polymers due to their high specific strength or high strength-to-density ratio, but are also characterized by poor bonding properties. At least one reason is believed to be the low surface energy properties of the plastics to be bonded.

[0008] Several strategies have been developed to bond surface films to such low-energy surfaces, including chemical priming, use of chemical adhesive compositions specifically formulated for bonding to such substrates, physical abrasion or chemical roughening, flame treatment, and acid or plasma etching to make the surface more bondable prior to application of adhesives or paints. However, each of these methods has tradeoffs that need to be considered.

[0009] It will be appreciated that chemical treatments such as acid etching or chemical activation are limited in commercial use due to safety and waste disposal issues, process control and cost.

[0010] Plasma technology requires large equipment. In addition to the capital cost, there are also difficulties with the size of the equipment, which makes it difficult to use it portable, for example in confined spaces.

[0011] Physical abrasion can also produce mixed results, as this method is difficult to adequately control and comes with the problem of waste abrasion byproducts.

[0012] While primers can do a great job, there is always a need for an alternative method of activating the surface for subsequent bonding. This applies especially to PEEK, PARA, PPS or PEI, which tend to be difficult to bond plastics and therefore often tend to have lower bond strengths than other plastics - and this often applies even when a primer is used.

[0013] Despite existing proposed solutions to these problems, it would be desirable to provide alternative solutions so that the end user has more available choices. Summary of the invention

[0014] The present disclosure relates to composite structures including thermoset surface films directly bonded to thermoplastic substrates, methods of making these composite structures, and articles including these composite structures.

[0015] In certain embodiments, the composite structure includes a thermoplastic substrate directly bonded to a thermosetting surface film; wherein the direct bonding defines an interface between the thermoplastic surface of the thermoplastic substrate and the first surface of the thermosetting surface film, and the thermosetting surface film further includes a second surface opposite to the first surface of the thermosetting surface film.

[0016] Definitions of thermoplastic substrates are provided elsewhere herein. Although not necessarily so limited, in certain more specific embodiments, the thermoplastic substrate comprises:

[0017] (a) polyaryletherketones, such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK); polyetheretherketoneketone (PEEKK); or polyetherketoneetherketoneketone (PEKEKK);

[0018] (b) polymers containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group, such as polyaromatic amides (PARA);

[0019] (c) Polyphenylene sulfide (PPS);

[0020] (d) polyphenylene oxide (PPO); or

[0021] (e) Polyetherimide (PEI).

[0022] Additionally or alternatively, the thermoplastic substrate comprises a thermoplastic polymer comprising some chemical bonds susceptible to at least partial photolytic cleavage when irradiated with actinic radiation of sufficient intensity and duration. In certain of these embodiments, the actinic radiation comprises radiation having at least one wavelength in the range of about 10 nm to about 500 nm or about 100 nm to about 450 nm, preferably in the range of about 200 nm to about 350 nm.

[0023] Additionally or alternatively, the thermoplastic substrate comprises a thermoplastic polymer having a bond having a thermal conductivity of about 0.1 J / cm2 at at least one wavelength. 2 To about 300J / cm 2 The energy range is preferably about 0.5 J / cm2 at at least one wavelength. 2 About 250 J / cm 2 or about 1.5J / cm 2 About 250 J / cm 2 The photocatalytic cracking occurs at least partially when the photocatalytic cracking occurs when the photocatalytic radiation of at least one wavelength is irradiated at an energy level within the range of 10 to 20 Å.

[0024] In a composite structure including a thermosetting surface film directly bonded to a thermoplastic substrate, the thermosetting surface film may be uncured (e.g., initially prepared) or partially cured (e.g., after some post-treatment). The thermosetting surface film adhered to a thermoplastic substrate or surface has a higher degree of cure than the thermosetting surface film when provided.

[0025] In a preferred embodiment, the thermosetting surface film is an epoxy-based thermosetting surface film. Various types of epoxy-based surface films are described herein.

[0026] As a composite material itself, in some embodiments, a surface film used or adhered to a substrate as disclosed herein comprises one or more organic, inorganic or metallic additives added to a polymer or prepolymer matrix, for example, additives such as flow agents, rheology modifiers, density regulators, impact modifiers, preservatives, pigments, colorants, etc.

[0027] Alternatively or additionally, the surface film may include at least one particle filler or additive comprising nano, micron and / or macro-dimensioned powders, particles, beads, flakes, whiskers or fibers. These forms depend on the material and the function of the specific material.

[0028] Alternatively or in addition, the surface film can comprise one or more organic or inorganic fibers, fabrics, weaves, meshes, or porous sheets contained in thermosetting (property) resin or polymer. In some of these embodiments, thermosetting (property) surface film comprises one or more peelable organic or inorganic fabrics, weaves, meshes, or porous sheets arranged on the second surface of thermosetting (property) surface film or below.

[0029] Alternatively or additionally, the surface film may include at least one electrically conductive material suitable for lightning strike protection, current dissipation, EMI shielding, or heat transfer applications.

[0030] Alternatively or in addition, the thermosetting surface film is adhered to a thermoplastic substrate to which the thermosetting surface film is directly bonded, and its strength is sufficient to score at least 3B, 4B or 5B according to ASTM D3359-09 for a 45° cross-hatched tape test, the conditions of which are more fully described in the examples.

[0031] Other embodiments include those methods of preparing directly bonded thermoplastic-thermoset composite structures. In some of these, the method includes:

[0032] (a) irradiating the surface of a thermoplastic substrate with actinic radiation sufficient to activate the surface of the thermoplastic substrate;

[0033] (b) contacting a thermosetting or thermosettable surface film with the activated thermoplastic substrate surface; and

[0034] (c) applying pressure to the thermosetting or thermosetting surface film close to the thermoplastic substrate and optionally applying heat for a period of time and under the condition of being enough to form direct bonding between the thermoplastic substrate and the thermosetting or thermosetting surface film. The method may further include curing the thermosetting or thermosetting surface film, thereby forming a composite structure comprising a thermoplastic substrate that is directly bonded to the thermosetting (property) surface film.

[0035] The method, the nature of the substrate, the surface film and the method of activating the bonding between them are consistent with the composite structure described elsewhere and will not be repeated here. Other aspects of the method (e.g., pressure and heat treatment) are further described elsewhere in this article.

[0036] Other aspects of the present disclosure include articles comprising these disclosed composite structures, and include parts or aircraft and land-based vehicles such as automobiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present application will be further understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the subject matter, exemplary embodiments of the subject matter are shown in the accompanying drawings; however, the presently disclosed subject matter is not limited to the specific methods, devices, and systems disclosed. In addition, the drawings are not necessarily drawn to scale. In the drawings:

[0038] Figure 1 Shown are the 45 degree cross-hatching and tape positions for the adhesion test described herein. DETAILED DESCRIPTION

[0039] The present disclosure relates to novel compositions of matter, including composite structures comprising thermoplastic substrates directly bonded to thermoset surface films, and methods of making and using these compositions.

[0040] By referring to the following description in conjunction with the accompanying drawings and examples (all of which constitute a part of the present disclosure), the present disclosure can be more easily understood.It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described or shown herein, and the terms used herein are only used to describe the specific embodiments that are only examples, and are not intended to limit any claimed invention.Similarly, unless otherwise specifically stated, any description of possible mechanism of action or mode of action or reason for improvement is intended only to be illustrative, and the disclosure herein is not subject to the correctness or incorrectness of any such suggested mechanism of action or mode of action or reason for improvement.Throughout this article, it should be recognized that descriptions relate to compositions and methods for preparing and using the compositions.That is, in the case of the features or embodiments related to compositions or methods for preparing or using compositions described in the present disclosure, it should be understood that such descriptions or requirements are intended to extend these features or embodiments to the embodiments in each of these contexts (i.e., compositions, methods for making and methods for using).

[0041] Composite structure

[0042] The present disclosure includes those embodiments of composite structures, wherein the composite structure includes a thermoplastic substrate that is directly bonded to a thermosetting (property) surface film. As used herein, the term "direct bonding" and grammatical variants thereof define the interface between the thermoplastic surface of a thermoplastic substrate and the first surface of a thermosetting (property) surface film, wherein the thermoplastic surface and the first surface adhere to each other at the surface forming the common boundary of the thermoplastic surface and the first surface, and preferably there is no material that is not derived from the thermoplastic surface and the first surface. The term "direct bonding" can also refer to such a mechanism, wherein in the presence of an intermediate linking group (e.g., without an external adhesive or similar composition), bonding is achieved between the complementary bonding parts in the thermosetting (property) surface film and the activated side group functional groups of the polymer part derived from the thermoplastic substrate are directly bonded to.

[0043] The thermosetting surface film further comprises a second surface opposite to the first surface of the thermosetting surface film. The second surface can be optionally functionalized as described elsewhere herein.

[0044] As described herein, the bonding between a thermoplastic substrate and a thermosetting surface film is described as wherein the thermoplastic substrate is directly bonded to the thermosetting surface film. Likewise, such bonding may be described as wherein the thermosetting surface film is directly bonded to the thermoplastic substrate, or wherein the thermosetting surface film and the thermoplastic substrate are directly bonded together. This distinction is merely semantic, and the descriptions should be considered equivalent throughout.

[0045] Thermoplastic substrate

[0046] In the context of the present disclosure, thermoplastic substrates comprise thermoplastic polymers as commonly understood by those skilled in the art of polymer chemistry, but in preferred embodiments, thermoplastic substrates comprise those thermoplastic polymers commonly used in the aerospace industry.

[0047] Even in this context, the thermoplastic polymer of the thermoplastic substrate is also broadly defined, but it seems that those thermoplastic polymers that contain bonds that are susceptible to photolytic cleavage when irradiated with actinic radiation of sufficient intensity are preferred. Such bonds include bonds containing heteroatoms, such as -O-, -S-, -C(O)-, -S(O)-, -S(O)2-, -C(O)O-, -C(O)-N-, or combinations thereof. Such thermoplastic polymers include, but are not limited to, one or more of the following as independent embodiments:

[0048] (a) polyaryletherketones, such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK); polyetheretherketoneketone (PEEKK); or polyetherketoneetherketoneketone (PEKEKK);

[0049] (b) polymers containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group, such as polyaromatic amides (PARA);

[0050] (c) Polyphenylene sulfide (PPS);

[0051] (d) polyphenylene oxide (PPO); or

[0052] (e) Polyetherimide (PEI).

[0053] In addition to the linking group, each of these polymers may contain pendant groups, so that, for example, the term "polyetheretherketone (PEEK)" refers to both substituted and unsubstituted (eg, substituted with alkyl groups) PEEK polymers.

[0054] As described elsewhere herein, the thermoplastic substrate may also be, and typically is, a composite material in which the thermoplastic polymer further comprises organic and / or inorganic additives such as flow agents, rheology modifiers, density regulators, preservatives, pigments, colorants, etc. The thermoplastic substrate is typically a structural reinforcement material optionally comprising fibers, webs, fabrics or porous sheets contained within a polymer matrix, and is preferably a fiber reinforced composite material comprising multiple layers of polymer composite materials containing oriented fibers, etc. (e.g., carbon fibers) arranged in a stack such that the fibers in adjacent or alternating layers are oriented transversely to each other.

[0055] Where the interface is described as being between a "thermoplastic surface of a thermoplastic substrate and a first surface of a thermosetting surface film", the thermoplastic surface is identical or chemically identical to the thermoplastic polymer of the thermoplastic substrate. In this regard, the term "chemically identical" means that the polymer building blocks of the substrate and the polymer building blocks of the surface are substantially identical, even if some of the binding sites of the surface have been altered by photolytic activation.

[0056] Where a thermoplastic polymer is described as comprising bonds susceptible to photolytic cleavage when irradiated with actinic radiation of sufficient intensity, in some embodiments, the actinic radiation comprises radiation having at least one wavelength in the range of about 10 nm to about 500 nm or about 100 nm to about 450 nm, preferably in the range of about 200 nm to about 350 nm. In further embodiments, the actinic radiation comprises radiation having one or more wavelengths in the range of about 100 nm to 125 nm, 125 to 150 nm, 150 nm to 175 nm, 175 nm to 200 nm, 200 nm to 225 nm, 225 nm to 250 nm, 250 nm to 275 nm, 275 nm to 300 nm, 300 nm to 325 nm, 325 nm to 350 nm, 350 nm to 375 nm, 375 nm to 400 nm, 400 nm to 425 nm, 425 nm to 450 nm, 475 nm to 500 nm, or in a range defined by any two or more of the above ranges, for example, 300 nm to 400 nm, or 275 nm to 325 nm. In other embodiments, the actinic radiation comprises light or radiation having at least one wavelength characterized as UV-A (about 315-400 nm, or 320-390 nm) and UV-B (280-315 nm, or 280-320 nm). In other embodiments, the actinic radiation comprises light or radiation having at least one wavelength characterized as UV-C (about 100-280 nm), UV-V (395-445 nm), near ultraviolet (NUV; 300-400 nm), mid ultraviolet (MUV; 200-300 nm), far ultraviolet (FUV; 122-200 nm), vacuum ultraviolet (VUV; 10-200 nm), or extreme ultraviolet (EUV; 10-120 nm).

[0057] Where thermoplastic polymers are described as comprising bonds susceptible to photolytic cleavage when irradiated with actinic radiation of sufficient intensity, in some embodiments, those polymers comprise a photosensitive polymer having ... 2 To about 300J / cm 2 The energy range is preferably about 0.5 J / cm2 at at least one wavelength. 2 About 250 J / cm 2 or about 1.5J / cm 2 About 250 J / cm 2 Other embodiments include those wherein the activation energy is from 0.1 to 0.5 J / cm 2 , 0.5 to 1 J / cm 2 , 1 to 1.5 J / cm 2 , 1.5 to 2 J / cm2 , 2 to 2.5 J / cm 2 , 2.5 to 3 J / cm 2 , 3 to 3.5 J / cm 2 , 3.5 to 4 J / cm 2 , 4 to 4.5 J / cm 2 , 4.5 to 5 J / cm 2 , 5 to 5.5 J / cm 2 , 5.5 to 6 J / cm 2 , 6 to 6.5 J / cm 2 , 6.5 to 7 J / cm 2 , 7 to 7.5 J / cm 2 , 7.5 to 8 J / cm 2 , 8 to 9 J / cm 2 , 9 to 10 J / cm 2 , 10 to 25 J / cm 2 , 25 to 50 J / cm 2 , 50 to 100 J / cm 2 , 100 to 150 J / cm 2 , 150 to 200 J / cm 2 , 200 to 250 J / cm 2 , 250 to 300 J / cm 2 One or more ranges in the range, or a range defined by any two or more of the above ranges, for example, 0.1 to 250 J / cm 2 , or 0.5 to 100 J / cm 2 Simultaneous or sequential illumination by two, three, four or more wavelengths or wavelength ranges is also considered to be a further independent embodiment.

[0058] Thermosetting surface film

[0059] In the context of the present disclosure, the thermosetting surface film comprises a thermosetting polymer commonly understood by those skilled in the art of polymer chemistry, but in a preferred embodiment, the thermosetting surface film comprises those (pre)polymer systems commonly used in the aerospace field in this context, for example, including benzoxazine, bismaleimide, epoxy resin, (meth)acrylate, (meth)acrylamide, polyamide, polyimide, polyurethane, vinyl ester or their copolymers or mixtures.

[0060] In terms of both functionality / performance and processability, epoxy-based thermosetting surface films appear to be preferred. In this context, in a specific embodiment, the epoxy-based surface film includes epoxy resins, including but not limited to one or more of the following: diglycidyl ethers of bisphenol A, F, S, E and M resins; epoxy novolacs; glycidyl ethers of mononuclear, dibasic, tribasic and polynuclear phenols; glycidyl ethers of tetraphenol ethane; hydroxyphenylmethane epoxy resins; naphthalene epoxy resins; triglycidyl ethers of aminophenol resins; tetraglycidyl ethers of methylenedianiline resins; glycidyl ethers of aliphatic polyols; alicyclic epoxy resins; modified classes of all epoxy types (containing halogens, silicon, phosphorus); toughened classes / adducts of all epoxy types with rubbers (such as butadiene, butadiene acrylonitrile copolymers). The inventors have seen that the present method EA 9845 Aero, EA9845 LC, EA 9845 P&P, EA9845LC P&P and EA 9837.1 epoxy composite surface films, in particular, have shown good results with PEEK substrates, and these are therefore considered to be preferred embodiments. In other independent embodiments, epoxy surface films designated as Loctite EA9837.1 Aero, Loctite EA 9837.1 BLK Aero, Loctite EA9837.1 LS Aero, Loctite EA9845 Aero, Loctite EA 9845 LC Aero, Loctite EA 9845 LA Aero, Loctite EA 9845 P&P Aero and Loctite EA 9845 LC P&P, as well as TenCate TC235SF-1, Aeroglide surface films, Surface Master 905 from Cytec and Redux 641 from Hexcel can also be used for these applications.

[0061] Independent embodiments include those in which the thermosetting surface film is not yet cured, partially cured, or fully cured when adhered to the thermoplastic surface. Each of these curing stages may occur at a different processing stage.

[0062] Usually, the total thickness that

[0001] thermosetting (property) surface film is applied is 12.5 to 12,500 microns (0.5 to 500 mil), preferably in the scope of 12.5 to 1250 microns (0.5 to 50 mil).In other embodiments, can be according to 12.5 to 25 microns, 25 to 50 microns, 50 to 75 microns, 75 to 100 microns, 100 to 125 microns, 125 to 150 microns, 150 to 175 microns, 175 to 200 microns, 200 to 250 microns, 250 to 300 microns, 300 to 400 microns, 400 to 450 microns, 450 to 500 microns, 500 to 1000 microns, 500 to 600 microns, 600 to 750 microns, 600 to 800 microns, 600 to 800 microns, 600 to 900 microns, 600 to 900 microns, 600 to 1000 microns, 600 to 1100 microns, 600 to 1200 microns, 600 to 1300 microns, 600 to 1500 microns, 600 to 1300 microns, 600 to 1500 microns, 600 to 1500 microns, 600 to 1600 microns, 600 to 1700 microns, 600 to 1800 microns, 600 to 1800 microns, 600 to 1800 microns, 600 to 1800 microns, 600 to The total thickness can be 25 to 300 microns, 10 to 500 microns, 15 to 2000 microns, 2000 to 2500 microns, 2500 to 5000 microns, 5000 to 7500 microns, 7500 to 10,000 microns, 10,000 to 12,500 microns, or a combination of two or more of these ranges, for example, 25 to 500 microns, 50 to 300 microns, or about 25 to 125 microns to describe the total thickness.

[0063] In other embodiments, the thermoset surface film may have a thermal conductivity of 0.005 to 0.15 lb. / ft. 2 (psf) or 24g / m 2 Up to 730g / m 2 Alternatively or additionally, the area mass may be from 25 to 50 g / m 2 , 50 to 100 g / m 2 100 to 200 g / m 2 , 200 to 300g / m 2 300 to 400 g / m 2 , 400 to 500g / m 2 , 500 to 600g / m 2 , 600 to 700g / m 2 or 700 to 730 g / m 2 For aircraft applications, the preferred range includes 0.005 to 0.01 psf (25 to 50 g / m 2 )、0.005 to 0.02psf(25 to 100g / m 2 )、0.005 to 0.03psf(25 to 150g / m 2 )、0.005 to 0.04psf(25 to 200g / m 2 )、0.005 to 0.05psf(25 to 250g / m 2 ) or 0.005 to 0.06psf (25 to 300g / m 2) or some combination of two or more of these ranges.

[0064] The same as the situation of thermoplastic substrate, thermosetting (property) surface film is also a kind of composite material, and this composite material comprises one or more organic, inorganic or metal additives that add in thermosetting (property) polymer or prepolymer matrix, for example, such as additives such as flow agent, rheology modifier, density regulator, preservative, pigment, coloring agent.In certain embodiments, these additives comprise continuous or chopped fiber, whisker, nano material, granular mineral matter, pottery, impact modifier and / or filling or hollow capsule.At least one particle filler or additive can comprise nanometer, micron and / or large-sized powder, particle, bead, thin slice, whisker or fiber, wherein at least one particle filler or additive comprises pottery, polymer, glass, or metal / metalloid material or its alloy, or the mixed material of coating, for example comprise carbide, nitride or oxide of aluminium, boron, silicon, tin, zirconium, or aluminium, carbon, copper, nickel, Sn-Zn or stainless steel, or aramid.These fillers can be evenly distributed on the whole thickness size of surface film basically, or can concentrate on one of its first or second surface. These particulate fillers may comprise one or more of any of the functional materials described herein, such as ceramics, polymers, glasses, or metallic / metalloid materials or alloys thereof.

[0065] Alternatively or additionally, such a surface film may comprise one or more organic, inorganic or metallic fibers, meshes, fabrics, or porous sheets contained within a thermosetting resin.

[0066] Such fibers can be used as reinforcing fibers including continuous or chopped fibers or whiskers of alumina, aramid, boron, carbon, glass, silicon carbide or mixtures thereof. Glass and / or carbon fibers are particularly preferred.

[0067] One or more organic or inorganic fibers, fabrics, braids, nets, or porous sheets can be included in thermosetting (property) resin or (preliminary) polymer, or can comprise one or more strippable organic or inorganic fabrics, braids, nets, or porous sheets arranged on the second surface of thermosetting (property) surface film or below. The use of this type of strippable material allows to remove strippable fabric, braids, nets or sheets from the second surface relative to the first surface of the thermosetting surface film subsequently, so that the nascent surface suitable for painting later can be provided. In certain embodiments of the present disclosure, composite structure is that such strippable layer is wherein removed, exposes such composite structure on the surface ready for painting.

[0068] In a further embodiment, the composite structure is a composite structure in which paint or other filling or unfilling or clear coating finishes have been applied to the surface ready for painting; That is, a composite structure in which the second surface of the thermosetting surface film is painted or coated in this way. The selection of paint is not restricted, as long as the paint is compatible with the final surface composition. Preferred paints are those that comprise polyacrylate, polyester, polymethacrylate, polyurethane or their copolymer or mixture. According to the property of the selected paint, the bonding of the paint to the exposed surface can be physical or chemical, or both. It is expected that, compared to what it has in addition in the absence of process described herein, the exposed surface will have the reactive chemical groups connected to the surface produced by the stripping process at a higher concentration. Therefore, it is also expected that, compared to what it has in the absence of the process, the final bonding between the exposed surface and the paint is more likely to have a higher contribution to the chemical interaction with the paint, thereby providing more complete bonding.

[0069] As used herein, the term "fabric" refers to a woven or nonwoven material. The term "membrane" means a flat polymer portion, consistent with its usual meaning. The fabric or membrane size can vary to include sheets, strips or continuous rolls. The membrane can be porous, semi-permeable or non-porous. Preferably, non-porous perforated membranes are preferred. Fabrics and membranes can all include materials including: polyester, polyamide, polyethylene, polypropylene, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), polyamide, polyaryletherketone (PAEK), polyethersulfone (PES), polyethyleneimine (PEI), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), fluorinated or perfluorinated polymers (such as polytetrafluoroethylene (PTFE or ), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF or )), or mixtures or copolymers thereof. Preferred exemplary fabrics may include polyester, polyamide, carbon fiber, glass or other inorganic fibers or For this purpose, polyester, nylon or their mixture can be used as fabric or film particularly.Every kind of fabric or film can be coated or impregnated by laminating adhesive resin.Resin can be 5 to 50 weight % or 10 to 40 weight % of the surface film composition.The arbitrary polymer surface of fabric or film can be coated with silicon dioxide, siloxane, aluminum oxide or metal randomly, or handle with plasma or silane.

[0070] The fabric or film can be a single layer or multilayer fabric construction. In the case where the fabric is woven, the woven fabric includes a tightly woven monofilament or multifilament bundle. Tight weaving, high-density weaving is preferred, to provide a smooth finish compatible with the desired finish of the final painted product. Therefore, preferred braids include plain weave, satin (harness satin) weaving, crowfoot satin (crowfoot satin) weaving, or twill, wherein the crowfoot satin weaving style is the most preferred. The polymer film can be envisioned as a final closed weave and calendered fabric, wherein the polymer film provides a surface roughness that can be significantly less than or even highly calendered closed weave fabric.

[0071] The tightness of braid can be described according to the warp and weft yarns per inch, and these two terms are easy to understand for the technicians in the field of woven fabrics. Fabric or film of the present invention include independently containing at least 80 warp yarns per inch, or at least 100,120,140 or 160 warp yarns per inch, and at least 40 weft yarns per inch, or at least 60,80 or 100 weft yarns per inch. For example, wherein fabric or film contains at least about 80 warp yarns per inch and at least about 40 weft yarns per inch, good results can be obtained. Preferred embodiments include those braids wherein fabric is woven with at least 120 warp yarns per inch and at least 60 weft yarns per inch. Such braids can be commercially available from PrecisionFabrics Group of Greensboro, North Carolina, for example, and those characterized by providing "fine surface look and feel" are most preferred. Exemplary compositions include 60004 / 56111 polyester, 51789 / 52006 nylon, and 52008 / 56115 nylon materials. Considering the warp / fill parameters, the fiber or yarn thickness is such as to provide a minimal open weave and is consistent with the thickness of the overall fabric.

[0072] Alternatively or in addition, thermosetting (property) surface film can comprise one or more second functional materials, and its at least a portion is the form of porous weaving or nonwoven fabric, expanded metal foil or polymer film, grid (grating), mesh (mesh), screen (screen) or net (web).In some preferred embodiments, the porous sheet of these additional functional materials is present in or on the surface film.As such, the surface film can be optionally single-function (for example, also comprising conductive metal wire or fiber) or multifunctional.This additional material comprises those conductive materials that are applicable to lightning protection, current dissipation, EMI shielding or heat transfer applications.

[0073] That is, in some embodiments, these additional functional materials may exist as multiple sheets of functional materials or as a single sheet that may include materials with multiple different functions (including so-called hybrid materials). It should be understood that the above-mentioned peelable porous sheet provides a functional capability (i.e., peelability), but in the context used here, the term "functional" refers to the properties of the sheet, which imparts certain characteristics of improved performance to the film, such as impact stability, dimensional stability, conductivity and heat transfer capability, thereby providing improved strength, EMI shielding materials, and static and lightning protection to the substrate to which it is ultimately attached. In addition, the phrase "at least one sheet of a second functional material" may be one or more sheets of non-peelable functional materials to distinguish them from peelable fabrics or sheets. That is, such second functional materials represent embodiments including the following: (a) one or more (non-peelable) functional materials, as described below; (b) two or more sheets of the same (non-peelable) functional material, (c) two or more sheets of different (non-peelable) materials, or (d) two or more sheets of two or more (non-peelable) functional materials.

[0074] Again, the porous sheets of the second functional material may include woven fabrics and expanded films, but in addition, these sheets may also include nonwoven fabrics, webs, screens or meshes of continuous or chopped organic or inorganic fibers, including materials that are the same or similar to those that can be used for the peelable porous sheets, i.e., one or more fluorinated or perfluorinated polymers (such as polytetrafluoroethylene (PTFE) or ), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF or )), (meth)acrylates, (meth)acrylamides, polyesters, polyamides, polyethylene, polypropylene, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyethersulfone (PES), polyethyleneimine (PEI)), poly-p-phenylene sulfide, polyvinyl chloride or copolymers or mixtures thereof. Other useful organic materials include polyaniline, polypyrrole, polythiophene or copolymers or mixtures thereof, which may be alone or mixed with any other material described for this purpose. Aramids (e.g. fibers) and imide fibers (e.g. ) are also attractive in this application. Since the intention is that the second functional material will remain in the multifunctional surface film after curing and during end use, the physical integrity or woven nature of these sheets is not as important as for the strippable materials; that is, they do not need to withstand the stripping operation.

[0075] Functional materials can also include ceramic or glass fibers (e.g., oxides, carbides, nitrides, carbon oxides, oxynitrides, carbonitrides or carbon oxynitrides comprising aluminum, boron, silicon and / or titanium), metal ceramic fibers, carbon or metal fibers (e.g., comprising aluminum, copper, iron, silver, tin or zinc, or mixtures, alloys), or coated blends comprising these materials. Exemplary materials include fibers or whiskers of aluminum oxide, aramid, boron, carbon, glass, silicon carbide, aluminum nitride, blends or mixtures thereof, preferably glass, carbon or metal coated fibers. As used herein, the term "fiber" includes those of large size, micron or nano size, and includes wires passing through elongated single crystals also referred to as whiskers. In some cases, these materials are composites of various material classes, for example, including carbon-coated metals, glasses or polymers; metal-coated polymers, carbon or glass; polymer-coated glass, carbon or metals, etc. In some cases, the functional material is conductive. In some embodiments, the functional material imparts magnetic properties to the surface film.

[0076] In a specific embodiment within this more general description, the composite structure includes an adhered thermoset surface film that is a multifunctional solid form composite material that includes two or more of:

[0077] (a) a first releasable fabric, woven fabric, mesh or porous sheet disposed at or below the second surface;

[0078] (b) at least one electrically conductive material suitable for use in lightning strike protection, current dissipation, EMI shielding, or heat transfer applications;

[0079] (c) at least one particulate filler or additive comprising nano-, micro- and / or macro-sized powders, particles, beads, flakes, whiskers or fibers, wherein at least one particulate filler or additive comprises a ceramic, polymer, glass, or a metal / metalloid material or alloy thereof, such as a carbide, nitride or oxide comprising aluminum, boron, silicon, tin, zirconium, or aluminum, carbon, copper, nickel, Sn-Zn or stainless steel, or an aramid; and optionally

[0080] (d) UV resistant polymers or UV stabilizing additives known in the art.

[0081] Physical properties of composite structures

[0082] The composite structures disclosed herein may also be characterized by one or more of their physical properties, such as the strength of direct bonding of thermoplastic and thermoset materials.

[0083] In certain embodiments, the thermoset surface film adheres to a thermoplastic substrate with sufficient strength to score at least 3B, 4B, or 5B for a 45° cross-hatch tape test according to ASTM D3359-09, the conditions of which are more fully described in the Examples.

[0084] Preparation method

[0085] At this point, the disclosure has described composite structures, but the disclosure also includes methods of making these structures.Alternative embodiments include those structures derived or derivable from the following methods, even if different than described in terms of a specifically disclosed composite structure.

[0086] As described herein, the present disclosure includes those methods of preparing directly bonded thermoplastic-thermoset composites comprising:

[0087] (a) irradiating the surface of a thermoplastic substrate with actinic radiation sufficient to activate the surface of the thermoplastic substrate;

[0088] (b) contacting a thermosetting or thermosettable surface film with the activated thermoplastic substrate surface; and

[0089] (c) applying pressure and optionally heat to the thermoset or heatsettable surface film against the thermoplastic substrate for a period of time and under conditions sufficient to form a direct bond between the thermoplastic substrate and the thermoset or heatsettable surface film.

[0090] In certain embodiments, the methods further include curing the thermoset or thermosettable surface film, thereby forming a composite structure including a thermoplastic substrate directly bonded to the thermoset surface film.

[0091] These embodiments include those methods using any of the thermoplastic substrates and surface films described elsewhere herein.

[0092] These embodiments also include the use of actinic radiation as described elsewhere herein. These are partially repeated here for completeness, including where actinic radiation is applied at a sufficient intensity at one or more wavelengths in the range of about 10 nm to about 450 nm, preferably in the range of about 200 nm to about 350 nm. Suitable subranges are described elsewhere herein. Similarly, about 0.1 J / cm at at least one wavelength may be used. 2 To about 300J / cm 2 The energy range is preferably about 0.5 J / cm2 at at least one wavelength. 2 About 250 J / cm 2 or about 1.5J / cm 2 About 250 J / cm 2Actinic radiation is applied at one or more wavelengths at an energy within a range of , or any one or more of the additional specific ranges set forth herein.

[0093] Further, the actinic radiation may be provided at about 2 mW / cm 2 About 3000mW / cm 2 , about 2mW / cm 2 About 2000mW / cm 2 , about 300mW / cm 2 to about 600mW / cm 2 , or preferably about 40 to 500 mW / cm 2 In certain other embodiments, the actinic radiation may be applied at a rate of from about 2 to about 5 mW / cm 2 , about 5 to about 10 mW / cm 2 , about 10 to about 25 mW / cm 2 , about 25 to about 50 mW / cm 2 , about 50 to about 100 mW / cm 2 , about 100 to about 200 mW / cm 2 , about 200 to about 300 mW / cm 2 , about 300 to about 400 mW / cm 2 , about 400 to about 500 mW / cm 2 , about 500 to about 600 mW / cm 2 , about 600 to about 700 mW / cm 2 , about 700 to about 800 mW / cm 2 , about 800 to about 900 mW / cm 2 , about 900 to about 1000 mW / cm 2 , about 1000 to about 2000 mW / cm 2 , about 2000 to about 3000 mW / cm 2 The rate described in one or more ranges is applied at one or more wavelengths. In some embodiments, the range is about 2 to 2000 mW / cm 2 , or preferably about 40 to 500 mW / cm 2 .

[0094] It should be understood that the time required for transmitting these energies depends on the properties of the substrate and the rate at which the energy is transferred to the substrate. Faster activation may be required for a continuously moving production line, such as when a continuous substrate passes through a light source to activate them. The duration of exposure may be about 0.1 second to about 360 minutes, such as about 0.5 second to about 180 minutes or about 0.5 second to about 30 minutes or about 3 seconds to about 19 minutes or less than about 240 seconds. From the perspective of output, the duration of exposure is preferably about 0.1 second to about 360 minutes.

[0095] Additionally or alternatively, actinic radiation can be applied at one or more of the aforementioned rates at one or more wavelengths for a time defined by one or more ranges of about 2 to about 5 seconds, about 5 to about 10 seconds, about 10 to about 20 seconds, about 20 to about 30 seconds, about 30 to about 40 seconds, about 40 to about 60 seconds, about 60 to about 80 seconds, about 80 to about 100 seconds, about 100 to about 200 seconds, about 200 to about 300 seconds, about 300 to about 400 seconds, about 400 to about 500 seconds, about 500 to about 600 seconds, or even longer to about 20 minutes, to about 60 minutes, or to 360 minutes.

[0096] The energy required to prepare any individual thermoplastic-thermoset bonding pair depends on the nature of the materials being bonded and the time available for such actinic activation. Good results have been obtained and are believed to be generally applicable after treatment using the following treatments:

[0097] UV-A (320-390nm) – 200mW / cm 2 x30sec=6000mJ / cm 2 =6J / cm 2

[0098] UV-B (280-320nm) – 306mW / cm 2 x30sec=9180mJ / cm 2 =9.2J / cm 2

[0099] UV-C (100-260nm) – 70mW / cm 2 x30sec=2100mJ / cm 2 =2.1J / cm 2

[0100] UV-V (395-445nm) – 200mW / cm 2 x30sec=6J / cm 2

[0101] It is suggested that, if not more generally, at least for the material tested, the following ranges, either individually or collectively, are appropriate:

[0102] UV-A(320-390nm)–100-400mW / cm 2 x10-120sec=1-48J / cm 2

[0103] UV-B (280-320nm) – 10-300mW / cm 2 x10-120sec=0.1-36J / cm 2

[0104] UV-C (100-260nm) – 5-200mW / cm 2 x10-120sec=0.5-24J / cm 2

[0105] UV-V (395-445nm) – 50-400mW / cm 2 x10-120sec=0.5-48J / cm 2

[0106] Irradiation using each of these ranges independently is considered a separate embodiment.

[0107] In all aspects of the invention, actinic radiation is referred to as actinic radiation from a light source that is intentionally and / or specifically arranged to illuminate the substrates to be bonded. In some instances, the source is within 1 meter of the substrate, such as within 30 cm thereof. More clearly, illumination with actinic radiation from such a light source is not intended to include, and in some embodiments specifically excludes, the use of ambient light, such as natural light, light from overhead lights, etc.

[0108] The methods described herein do not require the addition of an activator to the thermoplastic substrate. The methods also do not require any treatment that produces a physical change to the surface that promotes better adhesion, such as chemical etching (e.g., acid etching) or physical abrasion (e.g., sand / grit blasting) or other treatments (e.g., flame treatment; plasma treatment; ozone treatment, etc.).

[0109] Unless otherwise stated, the surface of the thermoplastic substrate is irradiated at otherwise ambient temperatures and conditions, but in some embodiments, the irradiation is carried out at super-ambient temperatures (e.g., one or more ranges of 20° C. to 25° C., 25° C. to 30° C., 30° C. to 40° C., 40° C. to 50° C., or 50° C. to 60° C. Additionally or alternatively, in separate embodiments, the irradiation can be carried out in the absence of oxygen, under vacuum conditions, in ambient air, or in an oxygen-enriched environment.

[0110] Irradiation can be carried out on the whole surface of thermoplastic substrate or on patterned part.For example, surface exposure to actinic radiation is selectively applied to produce surface area activated for subsequent bonding and surface area not activated for subsequent bonding.A mask can be used, and this mask has the area of ​​transmitting actinic radiation to produce the surface area activated for subsequent bonding area and blocking actinic radiation to produce the surface area not activated for subsequent bonding.As required, different equipment (point radiation source to large array radiation source) can be used to process small area or large area.Only area to be bonded needs to be exposed to radiation.If carried out in patterned or point-like manner, then the surface film will basically only adhere to those activated parts, or basically adhere much more than the non-activated part.

[0111] Without intending to be bound by the correctness of any particular theory, it is possible that actinic radiation activates the thermoplastic surface by breaking at least some of these heteroatom bonds, thereby providing activated pendant -OH, -SH, -C(O)H, -C(O)OH, or -C(O)-NH moieties, which, when present with reactive groups in the surface film, form cross-linked polymer bonds.

[0112] Once thermoplastic surface is activated, thermosetting (property) surface film is just applied pressure and optionally applies heat.In certain embodiments, the pressure applied is one or more pressures in the scope of about 0.05MPa to 1.2MPa, or in one or more scopes or aforementioned scopes in 0.05MPa to 0.1MPa, 0.1MPa to 0.2MPa, 0.2MPa to 0.3MPa, 0.3MPa to 0.4MPa, 0.4MPa to 0.5MPa, 0.5MPa to 0.6MPa, 0.6MPa to 0.7MPa, 0.7MPa to 0.8MPa, 0.8MPa to 0.9MPa, 0.9MPa to 1.0Mpa, 1.0MPa to 1.1MPa, 1.1MPa to 1.2MPa, two or more combinations, for example 0.4MPa to 0.8MPa, or one or more pressures in 0.6MPa to 0.7MPa. Pressure can apply 30 minutes to 60 minutes, 60 minutes to 90 minutes, 90 minutes to 120 minutes, 120 minutes to 180 minutes, 180 minutes to 240 minutes or longer time.In certain embodiments, during this pressure treatment, heat the composite structure of thermoplastic substrate and thermosetting (property) surface film.In other embodiments, do not apply external heat, but when applying, the temperature of this structure is heated to 150 ℃ to 160 ℃, 160 ℃ to 170 ℃, 170 ℃ to 180 ℃, 180 ℃ to 190 ℃, 190 ℃ to 200 ℃, for example one or more temperatures in 170 ℃ to 180 ℃ scopes.In independent embodiments, heating is applied some or all of the described time with static ground or with heating rate (such as described in the embodiment).

[0113] Once bonded, the bond strength between the thermoplastic substrate and the thermoset surface film is consistent with the bonding specifications described elsewhere herein.

[0114] Products that incorporate these composite structures

[0115] In addition to composite structures and methods of making them, the present disclosure contemplates all articles comprising these composite structures. Composite structures are suitable for articles of any size, but are particularly attractive for large structures. Contemplated structures include any primary structural element, secondary structural element, external element, internal element, and components forming these elements that may be in commercial and personal aircraft and aerospace applications, motor vehicles, watercraft (including ships), railcars, and tank cars and storage tanks.

[0116] That is, those aircraft parts that include any composite structure described herein are considered to be within the scope of the present disclosure. These include, but are not limited to, aircraft tails, wings, fuselages or propellers, and other corresponding features of winged or wingless air or space vehicles.

[0117] Further, those parts of land-based vehicles, such as automobiles, bicycles, motorcycles, trucks or boats, including any composite structure described herein are also considered to be within the scope of the present disclosure. These include, but are not limited to, hoods, fenders, bumpers, shells or frames.

[0118] the term

[0119] In this disclosure, the singular forms "a," "an," and "the" include plural referents, and references to values ​​include at least that value unless the context clearly dictates otherwise. Thus, for example, reference to "a material" is a reference to at least one of such materials and equivalents thereof known to those skilled in the art, and so forth.

[0120] When a value is expressed as an approximate value by using the descriptor "about", it will be understood that the value forms another embodiment. Generally, the use of the term "about" represents an approximate value, which can vary according to the desired characteristics attempted to be obtained by the disclosed subject matter, and should be interpreted in the specific context in which it is used based on its function. Those skilled in the art will be able to interpret it as usual. In some cases, the number of significant figures used for a value may be a non-limiting method for determining the degree of the word "about". In other cases, the grading used in a series of values ​​can be used to determine the expected range of the term "about" that can be used for each value. Where present, all ranges are inclusive and combinable. That is, the reference to the value stated in each range includes each value in the range.

[0121] It should be understood that, for clarity, certain features of the present disclosure described herein in the context of separate embodiments may also be provided in combination in a single embodiment. That is, unless clearly incompatible or explicitly excluded, each separate embodiment is considered to be combinable with any other embodiment, and such combination is another embodiment. Conversely, for brevity, various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although an embodiment may be described as part of a series of steps or part of a more general structure, each of the steps may also be considered as an independent embodiment that may be combined with others.

[0122] The transitional terms "comprising," "consisting essentially of," and "consisting of" are intended to convey their generally accepted meanings in national patents; that is, (i) "comprising," as synonymous with "including," "containing," or "characterized by," is inclusive and open-ended and does not exclude additional, unrecited elements or method steps; (ii) "consisting of" excludes any element, step, or ingredient not specified in the claim; and (iii) "consisting essentially of" limits the scope of a claim to the specified materials or steps, "and those that do not materially affect the basic and novel characteristics of the claimed invention." Embodiments described in accordance with the phrase "comprising" (or its equivalent) are also provided as embodiments that are independently described in accordance with "consisting of" and "consisting essentially of." For those embodiments provided in accordance with "consisting essentially of," the basic and novel feature is the ease of operation of the method or composition / system of the composite structure described herein or associated with the particular composition or method step.

[0123] When a list is given, it should be understood that each individual element of the list and each combination of the list is a separate embodiment unless otherwise stated. For example, a list of embodiments presented as "A, B, or C" will be interpreted to include embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B or C" as separate embodiments, as well as C. 1-3 .

[0124] The use of parentheses or brackets to describe materials such as (meth)acrylics or [meth]acrylics] or (pre)polymers is intended to imply the absence or presence of the term or phrase in the parentheses or brackets. For example, the term "(meth)acrylic" refers to one or both of acrylics and methacrylics. Thus, the term "(pre)polymer" refers to one or both of a polymer or a prepolymer (the latter including monomers or oligomers, and even non-crosslinked polymers, depending on the nature of the organic components).

[0125] Throughout the specification, words should be given their ordinary meanings as understood by those skilled in the relevant art. However, in order to avoid misunderstanding, the meanings of certain terms will be explicitly defined or clarified.

[0126] The term "actinic radiation" refers to a wavelength of electromagnetic radiation that can produce a photochemical reaction, including the ability of incident actinic radiation to activate a thermoplastic composition or surface. In various embodiments of the present disclosure, in addition to the specific ranges described elsewhere herein, the term "actinic radiation" also includes light or radiation having at least one wavelength characterized as UV-A (about 315-400 nm, or 320-390 nm) and UV-B (280-315 nm, or 280-320 nm). In other embodiments, the actinic radiation includes light or radiation having at least one wavelength characterized as UV-C (about 100-280 nm), UV-V (395-445 nm), near ultraviolet (NUV; 300-400 nm), mid-ultraviolet (MUV; 200-300 nm), far ultraviolet (FUV; 122-200 nm), vacuum ultraviolet (VUV; 10-200 nm), or extreme ultraviolet (EUV; 10-120 nm).

[0127] In the context of the present disclosure, the term "composite structure" refers to a layered structure resulting from direct bonding between a thermoplastic substrate and a thermosetting surface film. Recognizing that both the thermoplastic substrate and the thermosetting surface film themselves may also be considered as composite materials in the true sense of the term - i.e., a polymer or prepolymer matrix containing additives, fillers, fibers, etc. - if the term "composite material" is used in all of these contexts, these are referred to herein as composite thermoplastic substrates or composite surface films.

[0128] As conventionally understood, the term "curing" refers to the chemical process of producing toughening or hardening of polymer materials by crosslinking of polymer chains. It is closely related to the production of thermosetting polymers. Curing can be affected by heat, radiation, electron beams or chemical additives. As used herein, the term "partial curing" refers to any increase in the degree of crosslinking relative to the original polymer or prepolymer material.

[0129] "Optional" or "optionally" means that the subsequently described event may or may not occur, so that the description includes instances where the event occurs and instances where it does not.

[0130] The terms "method" and "process" are considered interchangeable in this disclosure.

[0131] The terms "photolysis", "photolytic", and the like refer to the controlled activation of a thermoplastic surface by the use of ultraviolet light, during which certain chemical bonds (usually those containing heteroatoms) are broken, thereby generating functional groups that make the surface more chemically active than an untreated surface. These more chemically active functional groups can or do bind to the thermosetting surface film during the curing of the surface film.

[0132] As used herein, the term "resin" has its conventional meaning of a liquid, usually viscous or highly viscous material that converts to a solid material upon curing.

[0133] The term "surface film" is a surface film of a composite material in solid form, which is well known in the field of aerospace engineering, and generally has an area weight of less than 0.150 pounds per square foot and a total thickness in the range of 25 to 12,500 microns (1 to 500 mils). They are generally applied to the surface of aircraft substrates to provide the surface quality required for aerospace applications. In certain embodiments, the reference to the surface film means this composite material added to one or more organic, inorganic or metal additives (for example, additives such as flow agents, rheology modifiers, density regulators, preservatives, pigments, colorants, etc.) in a polymer or prepolymer matrix. In other embodiments, the surface film may additionally or alternatively include one or more organic, inorganic or metal fibers, meshes, fabrics, or porous sheets contained in a thermosetting resin. In epoxy thermosetting surface films, thermosetting resins include epoxy resins. The surface film can optionally be monofunctional (for example, including conductive metal wires or fibers) or multifunctional (as in our previous applications).

[0134] As used herein, the term "thermoplastic" is a plastic polymer material that becomes pliable or moldable at certain elevated temperatures and hardens upon cooling. Thermoplastics contemplated in this disclosure, such as those used in aerospace applications, typically undergo this transition at elevated temperatures. Specific types of materials that the label comprises are disclosed elsewhere herein and include, but are not limited to, the following polymers: (meth)acrylics, acrylonitrile (including acrylonitrile butadiene styrene), ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), polyamide, polyamide-imide (PAI), polyaryletherketone (PAEK), polybenzimidazole, polycarbonate, polylactic acid (polylactide), polyethersulfone, polyoxymethylene (also known as acetal), polyetheretherketone, polyetherimide, polyetheretherketone (PEEK), polyetherimide (PEI), polyetherketoneketone (PEKK), polyethersulfone (PES), polyethylene, polyhydroxyalkanoate, polyimide, polyketone, polyphenylene ether, polyphenylene sulfide, polysulfone, polypropylene, polystyrene, polytetrafluoroethylene, polyurethane, polyvinyl chloride, and polyvinylidene fluoride.

[0135] The term "thermoset" or "thermosettable" is used herein in its conventional sense to refer to a polymer or prepolymer or resin that becomes irreversibly hardened or is irreversibly hardened (i.e., "thermoset") by a crosslinked network during curing. Crosslinked (meth) acrylics, (meth) acrylamides, benzoxazines, bismaleimides, epoxy resins, polyamides, polyimides, polyurethanes, vinyl esters, phenolic resins, amino resins and furan resins, or copolymers or mixtures thereof, are non-limiting examples of these types of materials.

[0136] As a matter of industry practice, the terms "thermoset" or "thermosetting" are used broadly to describe the properties of a polymer or surface film, regardless of the degree of cure. The term "thermoset" includes both partially or fully cured (thermoset) and uncured or less cured (thermoset or thermosettable) materials. Obviously, the degree of cure is a range for any material, but those skilled in the art will be able to distinguish the meaning of these terms in the context in which they are used.

[0137] "Thermosetting or thermosetting surface film" or "thermosetting (property) film", a composite material in solid form, including polymers or prepolymers cited respectively. Such surface films include polymers and / or prepolymers and one or more organic, inorganic or metal additives added to the polymer or prepolymer matrix, for example, additives such as flow agents, rheology modifiers, density regulators, preservatives, pigments, colorants, etc. These surface films may also optionally include one or more organic, inorganic or metal fibers, meshes, fabrics or porous sheets contained within or on a surface of the polymer or prepolymer matrix. In epoxy thermosetting surface films, thermosetting resins include epoxy resins. The surface film can be optionally monofunctional (for example, including conductive metal wires or fibers) or multifunctional (as described elsewhere in this article). It should be understood that the terms "thermosetting or thermosetting surface film" and "thermosetting surface film" refer to surface film compositions with different degrees of curing. For the sake of clarity, it should be understood that these terms should be considered in the context in which they appear.

[0138] The following list of embodiments is intended to supplement, not replace or supersede, the preceding descriptions.

[0139] Embodiment 1. A composite structure comprising a thermoplastic substrate bonded directly to a thermoset surface film;

[0140] Wherein direct bonding defines an interface between the thermoplastic surface of the thermoplastic substrate and the first surface of the thermosetting surface film, and the thermosetting surface film further includes a second surface opposite to the first surface of the thermosetting surface film.

[0141] Unless otherwise indicated, the thermoplastic surface is identical or chemically identical to the thermoplastic substrate, where the term "chemically identical" means that the polymer building blocks of the substrate and the surface are the same, even if some binding sites of the surface have been altered by photolytic activation.

[0142] Embodiment 2. A composite structure according to embodiment 1, wherein the thermoplastic substrate independently comprises:

[0143] (a) polyaryletherketones, such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK); polyetheretherketoneketone (PEEKK); or polyetherketoneetherketoneketone (PEKEKK);

[0144] (b) polymers containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group, such as polyaromatic amides (PARA);

[0145] (c) Polyphenylene sulfide (PPS);

[0146] (d) polyphenylene oxide (PPO); or

[0147] (e) Polyetherimide (PEI).

[0148] Embodiment 3. A composite structure according to embodiment 1 or 2, wherein the thermoplastic substrate comprises a thermoplastic polymer whose bonds are susceptible to at least partial photolytic cleavage when irradiated with actinic radiation of sufficient intensity, wherein the actinic radiation comprises radiation having at least one wavelength in the range of about 10 nm to about 500 nm or about 100 nm to about 450 nm, preferably in the range of about 200 nm to about 350 nm. Additional aspects of this embodiment include sub-ranges of these ranges described elsewhere herein.

[0149] Embodiment 4. A composite structure according to any one of embodiments 1 to 3, wherein the thermoplastic substrate comprises a thermoplastic polymer having a bond having a thermal conductivity of about 0.1 J / cm at at least one wavelength. 2 To about 300J / cm 2 The energy range is preferably about 0.5 J / cm2 at at least one wavelength. 2 About 250 J / cm 2 or about 1.5J / cm 2 About 250 J / cm 2 The invention relates to a method for preparing a photosensitive polymer having ...

[0150] Embodiment 5. A composite structure according to any one of Embodiments 1 to 4, wherein the thermoset surface film is directly bonded to the patterned portion of the thermoplastic surface.

[0151] Embodiment 6. A composite structure according to any one of Embodiments 1 to 5, wherein the thermosetting surface film is uncured.

[0152] Embodiment 7. A composite structure according to any one of Embodiments 1 to 6, wherein the thermosetting surface film is partially cured.

[0153] Embodiment 8. The composite structure according to any one of embodiments 1 to 7, wherein the thermosetting surface film is an epoxy-based thermosetting surface film.

[0154] Embodiment 9. A composite structure according to any one of embodiments 1 to 8, wherein the thermosetting surface film itself is a composite material in solid form comprising one or more organic or inorganic fibers, fabrics, weaves, meshes, or porous sheets contained in a thermosetting resin.

[0155] Embodiment 10. A composite structure according to any one of embodiments 1 to 9, wherein the thermosetting surface film is a composite material in solid form comprising one or more peelable organic or inorganic fabrics, woven fabrics, meshes, or porous sheets disposed at or below the second surface of the thermosetting surface film.

[0156] Embodiment 11. A composite structure according to any one of embodiments 1 to 10, wherein the thermosetting surface film is a composite material in solid form comprising one or more organic or inorganic fabrics, woven fabrics, meshes, or porous sheets contained in a thermosetting resin, and further comprises at least one conductive material suitable for lightning strike protection, current dissipation, EMI shielding or heat transfer applications.

[0157] Embodiment 12. A composite structure according to any one of Embodiments 1 to 11, wherein the epoxy-based thermosetting surface film is a composite material in solid form comprising one or more organic or inorganic fabrics, woven fabrics, meshes, or porous sheets, and further comprises at least one particulate material suitable for use as an impact modifier contained in a thermosetting resin.

[0158] Embodiment 13. A composite structure according to any one of embodiments 1 to 12, wherein the thermosetting surface film is a composite material in a multifunctional solid form comprising two or more of the following:

[0159] (a) a first releasable fabric, woven fabric, mesh or porous sheet disposed at or below the second surface;

[0160] (b) at least one electrically conductive material suitable for use in lightning strike protection, current dissipation, EMI shielding, or heat transfer applications;

[0161] (c) at least one particulate filler or additive comprising nano-, micro- and / or macro-sized powders, particles, beads, flakes, whiskers or fibers, wherein at least one particulate filler or additive comprises a ceramic, polymer, glass, or a metal / metalloid material or alloy thereof, such as a carbide, nitride or oxide comprising aluminum, boron, silicon, tin, zirconium, or aluminum, carbon, copper, nickel, Sn-Zn or stainless steel, or aramid;

[0162] (d) UV resistant polymers or UV stabilizing additives.

[0163] Embodiment 14. A composite structure according to any one of Embodiments 1 to 13, wherein the thermoset surface film has an area weight of less than 0.150 pounds per square foot.

[0164] Embodiment 15. A composite structure according to any one of embodiments 1 to 14, wherein the thermoset surface film has a total thickness in the range of 25 to 12,500 microns (1 to 500 mils). Additional aspects of this embodiment include sub-ranges of these ranges described elsewhere herein.

[0165] Embodiment 16. A composite structure according to any one of Embodiments 1 to 15, wherein a thermosetting surface film is adhered to a thermoplastic substrate directly bonded to the thermosetting surface film, and its strength is sufficient to score at least 3B, 4B or 5B for a 45° cross-hatch tape test according to ASTM D 3359-09 (the conditions of which are more fully described in the examples).

[0166] Embodiment 17. A method for preparing a directly bonded thermoplastic-thermoset composite, the method comprising:

[0167] (a) irradiating the surface of a thermoplastic substrate with actinic radiation sufficient to activate the surface of the thermoplastic substrate;

[0168] (b) contacting a thermosetting or thermosettable surface film with the activated thermoplastic substrate surface; and

[0169] (c) applying pressure and optionally heat to the thermoset or heatsettable surface film against the thermoplastic substrate for a period of time and under conditions sufficient to form a direct bond between the thermoplastic substrate and the thermoset or heatsettable surface film.

[0170] In certain independent aspects of this embodiment, irradiating is performed at ambient or super-ambient temperature and conditions, in the absence of oxygen, under vacuum conditions, in ambient air, or in an oxygen-enriched environment, as described elsewhere herein.

[0171] Embodiment 18. The method of embodiment 17, further comprising curing the thermoset or thermosettable surface film to form a composite structure comprising a thermoplastic substrate directly bonded to the thermoset surface film.

[0172] Embodiment 19. The method according to embodiment 17 or 18, wherein the thermoplastic substrate comprises:

[0173] (a) polyaryletherketones, such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK); polyetheretherketoneketone (PEEKK); or polyetherketoneetherketoneketone (PEKEKK);

[0174] (b) polymers containing a phenyl group directly attached to a carbonyl group, optionally wherein the carbonyl group is part of an amide group, such as polyaromatic amides (PARA);

[0175] (c) Polyphenylene sulfide (PPS);

[0176] (d) polyphenylene oxide (PPO); or

[0177] (e) Polyetherimide (PEI).

[0178] Embodiment 20. A method according to any one of embodiments 17 to 19, wherein the thermosetting or heat-curable surface film is an epoxy-type thermosetting or heat-curable surface film, and the corresponding thermosetting surface film is an epoxy-type thermosetting surface film.

[0179] Embodiment 21. The method according to any one of embodiments 17 to 20, wherein the actinic radiation is applied with sufficient intensity at one or more wavelengths in the range of about 10 nm to about 450 nm, preferably in the range of about 200 nm to about 350 nm. Additional aspects of this embodiment include sub-ranges of these ranges described elsewhere herein.

[0180] Embodiment 22. The method according to any one of embodiments 17 to 21, wherein about 0.1 J / cm at at least one wavelength 2 To about 300J / cm 2 The energy range is preferably about 0.5 J / cm2 at at least one wavelength. 2 About 250 J / cm 2 or about 1.5J / cm 2 About 250 J / cm 2 The invention also provides an embodiment of the present invention that provides an actinic radiation treatment method that is applied at one or more wavelengths at an energy within the range of . Additional aspects of this embodiment include sub-ranges of these ranges described elsewhere herein. Similarly, additional aspects of this embodiment include the application rates and times of actinic radiation described and illustrated elsewhere herein.

[0181] Embodiment 23. A method according to any one of Embodiments 17 to 22, wherein the pressure applied to the thermosetting surface film is 0.1 to 1 MPa, at one or more elevated temperatures, for example at 160°C to 180°C, for a time in the range of about 30 minutes to about 240 minutes.

[0182] Embodiment 24. A method according to any one of Embodiments 17 to 23, wherein the directly bonded thermoplastic-thermoset composite exhibits a bond strength between the thermoplastic substrate and the thermoset surface film of at least 3B, 4B or 5B based on a 45° cross-hatch tape test according to ASTM D3359-09.

[0183] Embodiment 25. A composite structure prepared by any one of Embodiments 17 to 24.

[0184] Embodiment 26. An aircraft component comprising the composite structure of any one of Embodiments 1 to 16. In certain aspects of this embodiment, the aircraft component comprises an aircraft tail, wing, fuselage, or propeller.

[0185] Embodiment 27. A component or part of a land-based vehicle such as an automobile, bicycle, motorcycle, truck, or boat comprising the composite structure of any one of embodiments 1 to 16. In certain aspects of this embodiment, the component comprises a hood, fender, bumper, skin, or frame.

[0186] Example

[0187] Standard application conditions

[0188] The surface of the thermoplastic substrate was cleaned under standard conditions using an isopropyl alcohol wipe to remove dust. Once cleaned, and where so indicated, the surface of the thermoplastic substrate was irradiated with UV light for a specified time and energy using a UVALOC 1000 source equipped with a D-type mercury lamp (iron-doped), after which a surface film was covered over the thermoplastic surface and the assembly was consolidated using a standard vacuum bag / autoclave process according to the following steps:

[0189] (1) The aluminum cover plate was wiped and cleaned with acetone, and then a release agent was applied to the plate except for the edges;

[0190] (2) The board edges are lined with vacuum sealant;

[0191] (3) The part / specimen is first pre-laid, where a one-side sticky (OST) surface film is laid on a thermoplastic substrate from its sticky side to make a sample. The sample is then placed within the boundaries of the cover plate by using an arrangement of a membrane material (nylon film), a sample, a perforated Teflon film, and a breathable cloth.

[0192] (4) Place a vacuum line vent on the board and cover the entire assembly with nylon film. Press the nylon film into the seal to form a tight seal. Evacuate to test the quality of the seal.

[0193] (5) Place the entire bagged board into an autoclave;

[0194] (6) The sample was cured under the following conditions: temperature: 177°C, heating rate: 1.7°C / min, pressure: 0.31 MPa, time: 120 min.

[0195] After this consolidation, the components were removed, visually inspected, and tested for adhesion.

[0196] Standard test conditions

[0197] Adhesion performance was evaluated using the cross-cut test method, where the test was performed as follows:

[0198] (1) Based on Figure 1 The specimen is scored with a cutting tool, where the cut is made through the coating (surface film) to the base material. The cutting tool can be a sharp razor blade, scalpel, or knife. In this test, a 45 degree cross-cut score is made, where the angle between two sets of parallel scores is 45 ± 5 degrees, and the parallel scores are about 3.05 mm apart.

[0199] (2) Figure 1 Apply masking tape (3M Tape No. 250) as shown. Press the tape down firmly using the roll of tape itself.

[0200] (3) One minute after applying the tape to the panel, remove the tape with one sudden motion and pulling perpendicular to the panel.

[0201] (4) Visually inspect and rate the test area according to ASTM D3359-09. The cross-cut rating is 0B to 5B, where 0B is the worst condition with an area removal percentage greater than 65%. The rating classification is summarized in Table 1.

[0202]

[0203] Material:

[0204] Thermoplastic substrate: The thermoplastic substrate used in these examples is a thermoplastic consolidated laminate (TPCL) made of several layers of thermoplastic powder woven fabric. The powder woven fabric contains high tenacity carbon fibers (Tenax-EHTA40 E13 3K200 tex) and a PEEK matrix (42 wt%). The fabric has a 5 Harness pattern and an area weight of 285 g / m 2 , the total panel thickness is 1.5mm.

[0205] Surface film: The surface film used in these examples is a dual-cure option (120-177°C) epoxy-based composite surface film and can be cured under non-autoclave conditions (in a vacuum bag with a low vacuum pressure of 0.07 MPa) or in an autoclave (with a higher pressure of 0.31 MPa). The surface film comprises a nonwoven (polyester or carbon) fabric and has a 146 g / m 2 total area weight.

[0206] Lightning strike surface film: This film is also a dual cure option (120-177°C) epoxy composite surface film and can be cured under non-autoclave conditions (in a vacuum bag with a low vacuum pressure of 0.07MPa) or in an autoclave (with a higher pressure of 0.31MPa). The lightning strike film further contains expanded copper foil (in addition to the non-woven polyester / carbon fabric). The area weight of the epoxy resin is 122g / m 2 , and the area weight of the copper foil is 70g / m 2 .

[0207] Stripping and paint surface film: This film is also a dual cure option (120-177°C) epoxy composite surface film and can be cured under non-autoclave conditions (in a vacuum bag with a low vacuum pressure of 0.07MPa) or in an autoclave (with a higher pressure of 0.31MPa) without any polyester / carbon nonwoven fabric. The film contains a plain weave pattern and 59g / m 2 After curing and peeling off the peel layer, the final area weight of the film is about 78g / m 2 .

[0208] Stripping and paint lightning strike film: This film is also a dual cure option (120-177°C) epoxy composite surface film and can be cured under non-autoclave conditions (in a vacuum bag with a low vacuum pressure of 0.07MPa) or in an autoclave (with a higher pressure of 0.31MPa) without any polyester / carbon nonwoven fabric. In addition to the nylon peel ply fabric, this film also contains expanded copper foil. The area weight of the copper foil is 70g / m 2 , and the total final area weight of the film after curing is about 148 g / m 2 .

[0209] Comparative Examples 1-4: No UV pretreatment.

[0210] Thermoplastic substrate is only processed to remove dust (that is, not applying ultraviolet light) by wiping the surface with isopropyl alcohol wipes. Corresponding surface film is covered on the PEEK surface and solidified as described above.The surface film used in these comparative examples is described in Table 2.In each case, the visual inspection of the gained surface film all demonstrates smooth and uniform surface.In each case, the cross-cutting assessment gives the rating of 0B.

[0211]

[0212] Example 1-4: Using UV pretreatment.

[0213] The conditions of the comparative example were repeated except that before covering the thermoplastic carbon reinforced substrate Tenax-E TPCL PEEK-HTA40 with the surface film, the substrate was irradiated with UV light for 30 seconds using a UVALOC 1000 source equipped with a D-type mercury lamp (iron doped). The pretreatment intensity of the various films is summarized in Table 3.

[0214]

[0215] In each case, the bond strength was evaluated by the cross-hatch test method and a score of 4B was obtained, indicating good adhesion. See Table 2.

[0216] As will be appreciated by those skilled in the art, numerous modifications and variations of the present disclosure are possible in light of these teachings, and all such modifications and variations are therefore contemplated.All references cited herein are incorporated herein by reference, at least for their teachings in the context in which they are presented.

Claims

1. A composite structure comprising a thermoplastic substrate bonded directly to a thermosetting surface film; Wherein the direct bonding defines an interface between the thermoplastic surface of the thermoplastic substrate and the first surface of the thermosetting surface film, and the thermosetting surface film further comprises a second surface opposite to the first surface of the thermosetting surface film; Among them, at 0.1J / cm 2 Up to 300J / cm 2 The thermoplastic substrate activated by at least one wavelength of actinic radiation at an energy within a range of: (a) polyaryletherketone; (b) polymers containing a phenyl group directly attached to a carbonyl group; (c) Polyphenylene sulfide (PPS); (d) polyphenylene oxide (PPO); or (e) polyetherimide (PEI); The thermosetting surface film is an epoxy-based thermosetting surface film, and is a composite material in a solid form comprising one or more strippable organic or inorganic fibers, fabrics, weaves, meshes, or porous sheets disposed at or below the second surface of the thermosetting surface film. The direct bonding is achieved by forming cross-linked polymer bonds between activated side functional groups derived from the polymer portion in the thermoplastic substrate and reactive groups in the epoxy-based thermosetting surface film in the absence of any external adhesive or similar composition.

2. The composite structure of claim 1, wherein the polyaryletherketone is polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetheretherketoneketone (PEEKK), or polyetherketoneetherketoneketone (PEKEKK).

3. The composite structure of claim 1, wherein in the polymer containing a phenyl group directly attached to a carbonyl group, the carbonyl group is part of an amide group.

4. The composite structure of claim 3, wherein the polymer containing a phenyl group directly attached to a carbonyl group is polyaromatic amide (PARA).

5. The composite structure of claim 1, wherein the actinic radiation comprises radiation having at least one wavelength in the range of 10 nm to 500 nm.

6. The composite structure of claim 5, wherein the actinic radiation comprises radiation having at least one wavelength in the range of 100 nm to 450 nm.

7. A composite structure according to claim 5 or 6, wherein the actinic radiation comprises radiation having at least one wavelength in the range of 200 nm to 350 nm.

8. The composite structure of claim 1, wherein the thermoplastic substrate comprises a thermoplastic polymer having a bond having a thermal conductivity of 0.5 J / cm2 at at least one wavelength. 2 Up to 250J / cm 2 The photocatalytic cracking occurs at least partially when the photocatalytic cracking occurs when the photocatalytic radiation of at least one wavelength is irradiated at an energy level within the range of 10 to 20 Å.

9. The composite structure of claim 8, wherein the bonds of the thermoplastic polymer have a thermal conductivity of 1.5 J / cm2 at at least one wavelength. 2 Up to 250J / cm 2 The photocatalytic cracking occurs at least partially when the photocatalytic cracking occurs when the photocatalytic radiation of at least one wavelength is irradiated at an energy level within the range of 10 to 20 Å.

10. The composite structure of claim 8 or 9, wherein the at least one wavelength comprises 1, 2, 3 or 4 wavelengths.

11. The composite structure of claim 1, wherein the thermosetting surface film is uncured.

12. The composite structure of claim 1, wherein the thermosetting surface film is partially cured.

13. A composite structure according to claim 1, wherein the thermosetting surface film is a composite material in solid form comprising one or more organic or inorganic fabrics, woven fabrics, meshes, or porous sheets contained in a thermosetting resin, and further comprises at least one conductive material suitable for lightning protection, current dissipation, EMI shielding or heat transfer applications.

14. A composite structure according to claim 1, wherein the epoxy-based thermosetting surface film is a composite material in solid form comprising one or more organic or inorganic fabrics, woven fabrics, meshes, or porous sheets, and further comprises at least one particulate material suitable for use as an impact modifier contained in a thermosetting resin.

15. The composite structure of claim 1, wherein the thermosetting surface film is a composite material in a multifunctional solid form comprising two or more of the following: (a) a first releasable fabric, woven fabric, mesh or porous sheet disposed at or below the second surface; and (b) at least one electrically conductive material suitable for use in lightning strike protection, current dissipation, EMI shielding, or heat transfer applications; (c) at least one particulate filler or additive comprising nano-, micro- and / or macro-sized powders, particles, beads, flakes, whiskers or fibers, wherein the at least one particulate filler or additive comprises a ceramic, polymer, glass, or a metallic / metalloid material or alloy thereof; or (d) UV resistant polymers or UV stabilizing additives.

16. The composite structure of claim 15, wherein the at least one particulate filler or additive comprises: - carbides, nitrides or oxides of: aluminium, boron, silicon, tin or zirconium; or - Aluminium, carbon, copper, nickel, Sn-Zn or stainless steel; or - Aramid.

17. A composite structure according to claim 1, wherein the thermosetting surface film is adhered to the thermoplastic substrate directly bonded to the thermosetting surface film with a strength sufficient to score at least 3B, 4B or 5B according to ASTM D3359-09 for a 45° cross-hatch tape test.

18. The composite structure of claim 1, wherein the thermoplastic substrate is a fiber reinforced composite material comprising multiple layers of a polymer composite material containing oriented fibers.

19. A method for preparing a directly bonded thermoplastic-thermoset composite material, the method comprising: (a) irradiating the surface of the thermoplastic substrate with actinic radiation sufficient to activate the surface of the thermoplastic substrate; (b) contacting the first surface of the thermosetting or thermosetting surface film with the activated thermoplastic substrate surface; and (c) applying pressure to the thermosetting or heat-settable surface film against the thermoplastic substrate for a period of time and under conditions sufficient to form a direct bond between the thermoplastic substrate and the thermosetting or heat-settable surface film, Where 0.1 J / cm at at least one wavelength 2 Up to 300J / cm 2 applying said actinic radiation at one or more wavelengths at an energy within a range of 10 to 20 ; wherein the thermoplastic substrate comprises: (a) polyaryletherketone; (b) polymers containing a phenyl group directly attached to a carbonyl group; (c) Polyphenylene sulfide (PPS); (d) polyphenylene oxide (PPO); or (e) polyetherimide (PEI), wherein the thermosetting or heat-settable surface film further comprises a second surface opposite to the first surface of the thermosetting or heat-settable surface film, The thermosetting or heat-setting surface film is an epoxy-based thermosetting or heat-setting surface film, and is a composite material in a solid form comprising one or more strippable organic or inorganic fibers, fabrics, weaves, meshes, or porous sheets disposed at or below the second surface of the thermosetting or heat-setting surface film. The direct bonding is achieved by forming cross-linked polymer bonds between activated side functional groups derived from the polymer portion in the thermoplastic substrate and reactive groups in the epoxy-based thermosetting or heat-curable surface film in the absence of any external adhesive or similar composition.

20. The method of claim 19, wherein the thermoplastic substrate is a fiber reinforced composite material comprising a multilayer polymer composite material containing oriented fibers.

21. The method of claim 19, further comprising curing the thermoset or thermosettable surfacing film to form a composite structure comprising a thermoplastic substrate directly bonded to the thermoset surfacing film.

22. The method of claim 19, wherein the polyaryletherketone is polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetheretherketoneketone (PEEKK), or polyetherketoneetherketoneketone (PEKEKK).

23. The method of claim 19, wherein in the polymer containing a phenyl group directly attached to a carbonyl group, the carbonyl group is part of an amide group.

24. The method of claim 23, wherein the polymer containing a phenyl group directly attached to a carbonyl group is polyaromatic amide (PARA).

25. The method of claim 19, wherein heat is applied while applying pressure to the thermosetting or thermosettable surface film against the thermoplastic substrate.

26. The method of claim 19, wherein the actinic radiation is applied at one or more wavelengths in the range of 10 nm to 450 nm with sufficient intensity.

27. The method of claim 26, wherein the actinic radiation is applied at a sufficient intensity at one or more wavelengths in the range of 200 nm to 350 nm.

28. The method of claim 19, wherein 0.5 J / cm at at least one wavelength 2 Up to 250J / cm 2 The actinic radiation is applied at one or more wavelengths at an energy within a range of .

29. The method of claim 28, wherein 1.5 J / cm at at least one wavelength 2 Up to 250J / cm 2 The actinic radiation is applied at one or more wavelengths at an energy within a range of .

30. The method according to claim 19, wherein the pressure applied to the thermosetting surface film is 0.4 to 1 MPa.

31. The method of claim 30, wherein pressure is applied at one or more elevated temperatures for a time in the range of 30 minutes to 240 minutes.

32. The method of claim 31 , wherein the one or more elevated temperatures are from 160°C to 180°C.

33. according to the method for claim 19, wherein said directly bonded thermoplastic-thermosetting composite material shows the bond strength between said thermoplastic substrate and said thermosetting surface film to show the score of at least 3B, 4B or 5B according to ASTM D3359-09 for 45 ° cross-hatch tape test.

34. A composite structure prepared by any one of claims 19 to 33.

35. An aircraft component comprising the composite structure of any one of claims 1 to 18.

36. An automotive component comprising the composite structure of any one of claims 1 to 18.

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