Patent Publication Number: US-2023159754-A1

Title: Thermoplastic films and methods for coating thermoplastic substrates with thermoset materials

Description:
FIELD 
     This application relates to thermoplastic compositions and, more specifically, to thermoplastic films and methods for coating thermoplastic substrates with thermoset materials in the aerospace industry. 
     BACKGROUND 
     The process of finishing polyaryletherketone-based structural thermoplastic composites presents challenges, specifically with respect to medium and large-scale components, particularly those used in airstream applications. Current surface treatment techniques include the need for mechanically treating substrate surfaces using techniques such as sand blasting, grit blasting, plasma treatment, and other techniques that roughen substrate surfaces prior to bonding with a thermoset material. 
     Conventional surface treatment techniques present challenges with respect to adhesion and miscibility. Therefore, those skilled in the art continue with research and development efforts in the field of coating thermoplastic substrates with thermoset materials. 
     SUMMARY 
     Disclosed are thermoplastic compositions. 
     In one example, the disclosed thermoplastic composition includes a thermoplastic polymer and a polyaryletherketone polymer in admixture with the thermoplastic polymer. 
     Also disclosed are consolidated laminate structures. 
     In one example, the disclosed consolidated laminate structure includes a thermoplastic substrate including a thermoplastic polymer and a thermoplastic composition consolidated with the thermoplastic substrate to define a receiving surface. The thermoplastic composition includes a thermoplastic polymer and a polyaryletherketone polymer in admixture with the thermoplastic polymer. 
     Also disclosed are methods for manufacturing consolidated laminate structures. 
     In one example, the disclosed method for manufacturing a consolidated laminate structure includes applying a thermoplastic composition to a first major surface of a thermoplastic substrate. The thermoplastic composition includes a thermoplastic polymer and a polyaryletherketone polymer in admixture with the thermoplastic polymer. The method further includes co-consolidating the thermoplastic composition with the thermoplastic substrate to define a receiving surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a method for forming a thermoplastic film; 
         FIG.  2    is a cross sectional schematic of a laminate structure prior to consolidation; 
         FIG.  3    is a cross sectional schematic of the laminate structure of  FIG.  2    after consolidation; 
         FIG.  4    is a cross sectional schematic of the laminate structure of  FIG.  3    with an additional coating; 
         FIG.  5    is a cross sectional schematic of the laminate structure of  FIG.  4    with an additional coating; 
         FIG.  6    is a flow diagram of a method for manufacturing a consolidated laminate structure; 
         FIG.  7    is a block diagram of aircraft production and illustrative methodology; and 
         FIG.  8    is a schematic illustration of an aircraft. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed are compositions and methods for chemically modifying a receiving surface of a thermoplastic composite substrate. The compositions and methods improve compatibility of a thermoplastic composite substrate and a thermoset coating, such as an epoxy-based primer. The disclosed compositions and methods account for threshold adhesive properties with the thermoset coating and miscibility of the components of the compositions. The result is a modified surface of the thermoplastic composite material to enhance compatibility to a thermoset coating. 
     Referring to  FIG.  1   , disclosed is a thermoplastic composition  120 ′. The thermoplastic composition includes a thermoplastic polymer  116  and a polyaryletherketone polymer  118  in admixture with the thermoplastic polymer  116 . The thermoplastic composition may be manufactured by combining and blending the thermoplastic polymer and the polyaryletherketone polymer  118  in an extruder and extruding the resulting composition into a coating, such as a film  120 . 
     As shown in  FIGS.  2  and  4   , the thermoplastic polymer  116  ( FIG.  1   ) of the thermoplastic composition  120 ′ may be selected based upon material properties such as threshold adhesive properties that align with a mating thermoset coating  130  and miscibility with the thermoplastic substrate  110  material such that a first major surface  112  of a receiving thermoplastic substrate  110  is modified to enhance compatibility with a thermoset coating  130 . Further, the thermoplastic polymer  116  is miscible with polyaryletherketone polymers. In one example, the thermoplastic polymer  116  of the thermoplastic composition  120 ′ includes polyetherimide. The thermoplastic polymer  116  may be amorphous. The thermoplastic polymer  116  is compatible with aerospace grade paints and coatings and is stable at processing temperatures of at least about 350° C. 
     In one example, the polyaryletherketone polymer  118  is a semi-crystalline material belonging to the family of polyaryletherketone (PAEK) polymers. The polyaryletherketone polymer  118  may be in the form of a film plastic pellets, powder, etc. The polyaryletherketone polymer  118  may include polyether ether ketone. In another example, the polyaryletherketone polymer includes polyether ketone ketone. In yet another example, the polyaryletherketone polymer includes a blend of at least two polyaryletherketones. For example, the polyaryletherketone polymer may include a blend of polyether ketone ketone and polyether ether ketone. 
     The thermoplastic composition  120 ′ has a melting temperature based upon the ratio of thermoplastic polymer  116  to the polyaryletherketone polymer  118  and the respective melting temperatures of each of the thermoplastic polymer to the polyaryletherketone polymer  118 . In one example, the melting temperature of the polyaryletherketone polymer  118  is about 275° C. to about 350° C. In another example, the melting temperature of the polyaryletherketone polymer  118  is at least about 300° C. 
     The thermoplastic composition  120 ′ includes a ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118 . In one example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 1:20 and about 1:1. In another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 10:90 and about 50:50. In another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 1:9 and about 1:1. In yet another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 20:80 and about 50:50. 
     The thermoplastic composition  120 ′ includes a degree of crystallinity such that it is a semi-crystalline material. In one example, the degree of crystallinity is from about 1 percent to about 30 percent. In another example, the degree of crystallinity is from about 2 percent to about 15 percent. In yet another example, the degree of crystallinity is from about 3 percent to about 10 percent. 
     The thermoplastic composition  120 ′ may include additional additives. In one example, the thermoplastic composition  120 ′ includes a heat stabilizer. In another example, the thermoplastic composition  120 ′ includes a nucleating agent. 
     Referring to  FIG.  2   , the thermoplastic composition  120 ′ may be extruded into a film  120  for application on a thermoplastic substrate  110  to form a laminate structure  100 ′. In one example, the film  120  has a thickness of about 1 mil to about 15 mil. The laminate structure  100 ′ may be co-consolidated into a consolidated laminate structure  100 , see  FIG.  3   . In one example, the consolidated laminate structure  100  includes a thermoplastic substrate  110 . The thermoplastic substrate  110  includes a thermoplastic polymer. In one example, the thermoplastic polymer of the thermoplastic substrate  110  includes a polyaryletherketone polymer. 
     The thermoplastic substrate  110  may be formed of at least two plies  110 ′ of laminate in a stacked configuration. The at least two plies  110 ′ of laminate may include a polymer from the family of polyaryletherketone (PAEK) polymers. In one example, the at least two plies  110 ′ of laminate include polyether ketone ketone. 
     The consolidated laminate structure  100  further includes a thermoplastic composition  120 ′ consolidated with the thermoplastic substrate  110  to define a receiving surface  114  of the consolidated laminate structure  100 . The thermoplastic composition  120 ′ includes a thermoplastic polymer  116  and a polyaryletherketone polymer  118  in admixture with the thermoplastic polymer  116 . 
     The thermoplastic polymer  116  of the thermoplastic composition  120 ′ may be selected based upon material properties such as threshold adhesive properties that align with a mating thermoset coating  130  and miscibility with the thermoplastic substrate  110  material such that a first major surface  112  of a receiving thermoplastic substrate  110  is modified to enhance compatibility with a thermoset coating  130 . In one example, the thermoplastic polymer of the consolidated laminate structure  100  includes polyetherimide. The thermoplastic polymer  116  may be amorphous. The thermoplastic polymer  116  is compatible with aerospace grade paints and coatings and is stable at processing temperatures of at least about 350° C. 
     In one example, the polyaryletherketone polymer  118  of the consolidated laminate structure  100  includes at least one of polyether ether ketone and polyether ketone ketone. In another example, the polyaryletherketone polymer  118  of the consolidated laminate structure  100  includes a blend of polyether ether ketone and polyether ketone ketone. 
     In one example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 1:20 and about 1:1. In another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 10:90 and about 50:50. In another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 1:9 and about 1:1. In yet another example, the ratio of the thermoplastic polymer  116  to the polyaryletherketone polymer  118  is between about 20:80 and about 50:50. 
     Referring to  FIG.  4   , the consolidated laminate structure  100  may further include a thermoset material  130 ′ applied to the receiving surface  114 . In one example, the thermoset material  130 ′ is in the form of a thermoset coating  130 . In one example, the thermoset material  130 ′ may include an epoxy. In another example, the thermoset material  130 ′ may be a primer, such as a paint primer. Additionally, the consolidated laminate structure  100  may further include a top coat  140  applied to the thermoset material  130 ′, or primer, see  FIG.  5   . In one example, the top coat  140  includes polyurethane. 
     Referring to  FIG.  6   , disclosed is a method  600  for manufacturing a consolidated laminate structure  100 . The method  600  includes applying a thermoplastic composition to a first major surface  112  of a thermoplastic substrate  110 . In one example, the thermoplastic substrate is a layered structure including at least two layers of thermoplastic material. 
     The thermoplastic composition  120 ′ of the method  600  includes a thermoplastic polymer  116  and a polyaryletherketone polymer in admixture with the thermoplastic polymer  116 . In one example, the thermoplastic polymer  116  comprises polyetherimide. Further, in one or more examples, the polyaryletherketone polymer  118  comprises at least one of polyether ether ketone and polyether ketone ketone, or a blend of polyether ether ketone and polyether ketone ketone. 
     In one example, the thermoplastic substrate  110  of the method  600  includes a polyaryletherketone polymer  118 . Further, in one or more examples, the polyaryletherketone polymer of the thermoplastic composition  120 ′ and the polyaryletherketone polymer of the thermoplastic substrate  110  are one and the same. 
     Still referring to  FIG.  6   , the method  600  further includes co-consolidating  640  the thermoplastic composition with the thermoplastic substrate  110  to define a receiving surface  114 . In one or more examples, the co-consolidating  640  is performed at a temperature of about 275° C. to about 400° C. In another example, the co-consolidating  640  is performed at a temperature of about 330° C. to 400° C. In yet another example, the co-consolidating  640  is performed at a temperature of at least 340° C. The co-consolidating  640  may include any means including compression molding or stamp forming. 
     The method  600  may further include applying  650  a thermoset material  130 ′, such as a thermoset coating  130 , to the receiving surface  114 . In one example, the thermoset material  130 ′ of the method  600  includes an epoxy. In another example, the thermoset material  130 ′ of the method  600  is a primer, such as a paint primer. Referring to  FIG.  5   , the method  600  may further include applying a top coat  140  to the thermoset material  130 ′. In one example, the top coat  140  includes polyurethane. 
     Still referring to  FIG.  6   , the method  600  may further include, prior to the applying  630 , extruding  620  the thermoplastic polymer  116  and the polyaryletherketone polymer  118  to yield the thermoplastic composition  120 ′. The extruding  620  may include extruding  620  the thermoplastic composition  120 ′ to a thermoplastic film  120 . 
     The method  600  may further include, prior to the applying  630 , arranging  610  at least two plies  110 ′ of laminate in a stacked configuration to yield the thermoplastic substrate  110 . The arranging  610  may be performed by any suitable means of arranging plies of laminate. The at least two plies  110 ′ of laminate may include at least one of polyether ether ketone and polyether ketone ketone, or a blend thereof. 
     Referring to  FIG.  7    and  FIG.  8   , the disclosed consolidated laminate structure  100 , thermoplastic composition  120 ′ and method  600  will be used in the context of aircraft manufacturing and service including material procurement (block  1106 ), production, component and subassembly manufacturing (block  1108 ), and certification and delivery (block  1112 ) of aircraft  1102 . 
     Examples of the subject matter disclosed herein may be described in the context of aircraft manufacturing and illustrative method  1100  as shown in  FIG.  7    and aircraft  1102  as shown in  FIG.  8   . In one or more examples, the consolidated laminate structure  100  comprises a stringer assembly used in aircraft manufacturing. During pre-production, illustrative method  1100  may include specification and design (block  1104 ) of aircraft  1102  and material procurement (block  1106 ). During production, component and subassembly manufacturing (block  1108 ) and system integration (block  1110 ) of aircraft  1102  may take place. Thereafter, aircraft  1102  may go through certification and delivery (block  1112 ) to be placed in service (block  1114 ). While in service, aircraft  1102  may be scheduled for routine maintenance and service (block  1116 ). Routine maintenance and service may include modification, reconfiguration, refurbishment, etc. of one or more systems of aircraft  1102 . 
     Each of the processes of illustrative method  1100  may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include, without limitation, any number of aircraft manufacturers and major-system subcontractors; a third party may include, without limitation, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on. 
     As shown in  FIG.  8   , aircraft  1102  produced by illustrative method  1100  may include airframe  1118  with a plurality of high-level systems  1120  and interior  1122 . Examples of high-level systems  1120  include one or more of propulsion system  1124 , electrical system  1126 , hydraulic system  1128 , and environmental system  1130 . Any number of other systems may be included. Although an aerospace example is shown, the principles disclosed herein may be applied to other industries, such as the automotive industry. Accordingly, in addition to aircraft  1102 , the principles disclosed herein may apply to other vehicles, e.g., land vehicles, marine vehicles, space vehicles, etc. 
     Apparatus(es) and method(s) shown or described herein may be employed during any one or more of the stages of the manufacturing and illustrative method  1100 . For example, components or subassemblies corresponding to component and subassembly manufacturing (block  1108 ) may be fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft  1102  is in service (block  1114 ). Also, one or more examples of the apparatus(es), method(s), or combination thereof may be utilized during production stages component and subassembly manufacturing (block  1108 ) and system integration (block  1110 ), for example, by substantially expediting assembly of or reducing the cost of aircraft  1102 . Similarly, one or more examples of the apparatus or method realizations, or a combination thereof, may be utilized, for example and without limitation, while aircraft  1102  is in service (block  1114 ) and/or during maintenance and service (block  1116 ). 
     Different examples of the composition(s), structure(s) and method(s) disclosed herein include a variety of components, features, and functionalities. It should be understood that the various examples of composition(s), structure(s) and method(s), disclosed herein, may include any of the components, features, and functionalities of any of the other examples of the composition(s), structure(s) and method(s) disclosed herein in any combination. 
     Many modifications of examples, set forth herein, will come to mind of one skilled in the art, having the benefit of the teachings, presented in the foregoing descriptions and the associated drawings. 
     Therefore, it is to be understood that the subject matter, disclosed herein, is not to be limited to the specific examples illustrated and that modifications and other examples are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and the associated drawings describe examples of the subject matter, disclosed herein, in the context of certain illustrative combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative implementations without departing from the scope of the appended claims. Accordingly, parenthetical reference numerals in the appended claims are presented for illustrative purposes only and are not intended to limit the scope of the claimed subject matter to the specific examples provided herein.