An interior trim (INS) film and a method of manufacturing the same

Abstract

The application discloses an interior neuter system (INS) film for a car and a preparation method thereof. The INS film comprises a weather-resistant layer, a pattern layer, a bonding layer and a substrate layer in sequence. The side of the substrate layer away from the weather-resistant layer is suitable for fusion cross-linking forming with plastic. The preparation raw material of the substrate layer comprises a modified aldehyde ketone resin. The addition amount of the modified aldehyde ketone resin is 0.2%-1% of the total mass of the raw material of the substrate layer. The modified aldehyde ketone resin is introduced into ABS, the combination state between the INS film and parts of the car is improved, a more compact and stable connection can be formed after injection molding, the adhesion is enhanced, the possibility of falling off of the INS film in the use process is fundamentally reduced, and the overall service life of the INS film for the car is correspondingly prolonged.

Description

Technical Field

[0001] This application relates to the field of functional membrane technology, specifically to an automotive interior INS film and its preparation method. Background Technology

[0002] INS film technology is a technique that combines a pre-printed or molded decorative film with a substrate within a mold using a specific process, forming an integrated decorative component. Currently, there are many types of substrates for INS films used in automotive interiors. Among them, ABS (acrylonitrile-butadiene-styrene copolymer) is often used as a substrate due to its good overall properties, such as strength, toughness, and processability. In practical applications, the INS film needs to be tightly bonded to the plastic substrate of the automotive interior (such as PP, PC, etc.) to ensure the overall performance and reliability of the interior components.

[0003] However, the bonding between ABS-based INS films and commonly used plastic substrates in automotive interiors is often less than ideal in existing technologies. This is mainly because ABS differs from other plastic substrates in chemical structure and surface energy, resulting in weaker interfacial adhesion. During long-term use of a car, factors such as temperature changes, vibration, and external friction can easily cause the INS film to peel or detach from the plastic substrate. This not only severely affects the aesthetics of the car's interior but may also damage interior components, reduce the driving experience, and even pose certain safety hazards.

[0004] Therefore, how to improve the adhesion between ABS-based automotive interior INS film and plastic substrate and prevent INS film from falling off has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to improve the problem of peeling and detachment between the INS film and the plastic substrate.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: providing an automotive interior INS film, comprising a weather-resistant layer, a pattern layer, an adhesive layer, and a substrate layer in sequence. The side of the substrate layer away from the weather-resistant layer is suitable for fusion and cross-linking molding with plastic. The raw materials for preparing the substrate layer include modified aldehyde-ketone resin, and the amount of modified aldehyde-ketone resin added is 0.2% to 1% of the total mass of the raw materials of the substrate layer.

[0007] As a preferred embodiment, the raw materials for preparing the modified aldehyde-ketone resin include: aldehyde monomers, ketone monomers, hydroxyl monomers, and catalysts.

[0008] As another preferred embodiment, the hydroxyl monomer is any one or more of glycerol, pentaerythritol, and polyethylene glycol.

[0009] As another preferred method, the modified aldehyde-ketone resin is prepared by: adding the aldehyde monomer and the ketone monomer to a reaction vessel, adding an acid catalyst and heating the reaction for a period of time, adding a first hydroxyl monomer to continue the reaction, obtaining a hydroxyl-containing aldehyde-ketone resin precursor, dissolving the hydroxyl-containing aldehyde-ketone resin precursor and adding a second hydroxyl monomer and catalyst to heat the reaction, and removing impurities after cooling to obtain the modified aldehyde-ketone resin.

[0010] As another preferred embodiment, the first hydroxyl monomer is pentaerythritol, and the second hydroxyl monomer is polyethylene glycol.

[0011] As another preferred option, the raw materials for preparing the substrate layer also include a compatibilizer and an antioxidant, and the total amount of the compatibilizer and the antioxidant added is 1% to 4% of the total mass of the substrate layer.

[0012] As another preferred option, an adhesive is applied to one side of the substrate layer to form the adhesive layer, wherein the adhesive is a polyurethane adhesive.

[0013] As another preferred embodiment, the thickness of the weather-resistant layer is 20~100 μm, and the thickness of the substrate layer is 250~500 μm.

[0014] This application also provides a method for preparing an automotive interior INS film, comprising the following preparation methods: S1: preparing a modified aldehyde-ketone resin using aldehyde monomers, ketone monomers, a first hydroxyl monomer, and a second hydroxyl monomer; S2: uniformly mixing ABS, the modified aldehyde-ketone resin, a compatibilizer, and an antioxidant, adding the mixture to a twin-screw extruder for melt extrusion to obtain a substrate layer, and coating one side of the substrate layer with an adhesive; S3: melt extruding PMMA in a twin-screw extruder to obtain a weather-resistant layer, setting a pattern layer on one side of the weather-resistant layer, bonding the pattern layer to the substrate layer coated with the adhesive, and curing to obtain the automotive interior INS film.

[0015] Further preferably, the pattern layer is formed on one side of the weather-resistant layer using one or more processes such as gravure printing, screen printing, vapor deposition, or sputtering.

[0016] Compared with the prior art, the beneficial effects of this application are as follows:

[0017] (1) By introducing modified aldehyde and ketone resin into ABS, this application improves the bonding state between the automotive interior INS film and the parts, so that a tighter and more stable connection can be formed after injection molding, the adhesive performance is enhanced, and the possibility of the INS film falling off during use is fundamentally reduced, thereby extending the overall service life of the automotive interior INS film.

[0018] (2) In the process of preparing modified aldehyde and ketone resin, the first hydroxyl monomer and the second hydroxyl monomer are used in this application, which effectively improves the compatibility of modified aldehyde and ketone resin;

[0019] (3) Based on the material of the substrate layer, this application selectively uses polyurethane adhesives, which can further improve the stability between INS film layers. Detailed Implementation

[0020] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0021] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0022] The automotive interior INS film of this application includes a weather-resistant layer, a pattern layer, an adhesive layer, and a substrate layer, wherein the raw materials for preparing the substrate layer include ABS and modified aldehyde-ketone resin.

[0023] This application improves the bonding between the automotive interior INS film and parts by introducing modified aldehyde-ketone resin into ABS, enabling a tighter and more stable connection after injection molding. The adhesive performance is enhanced, fundamentally reducing the possibility of the INS film falling off during use and reducing various problems caused by falling off. At the same time, it also extends the overall service life of the automotive interior INS film, allowing it to maintain good performance and condition for a longer period of time.

[0024] The raw materials for preparing the modified aldehyde-ketone resin in this application include: aldehyde monomers, ketone monomers, hydroxyl monomers, and a catalyst. The modified aldehyde-ketone resin is a hydroxyl-modified aldehyde-ketone resin. Introducing hydroxyl monomers into the aldehyde-ketone resin improves its compatibility with ABS materials and enhances the adhesion between ABS and the parts after injection molding. Furthermore, the addition of the modified aldehyde-ketone resin does not alter the transparency of the automotive interior INS film, allowing for a superior presentation of the automotive interior finish.

[0025] In some embodiments, aldehyde monomers and ketone monomers are raw materials suitable for synthesizing aldehyde-ketone resins, which have been disclosed in detail in the prior art and will not be repeated here.

[0026] In some embodiments, the hydroxyl monomer is any one or more of glycerol, pentaerythritol, and polyethylene glycol.

[0027] In some embodiments, the modified aldehyde-ketone resin is prepared by: adding aldehyde monomers and ketone monomers into a reaction vessel, adding an acid catalyst and heating the reaction for a period of time, adding a first hydroxyl monomer to continue the reaction, and obtaining a hydroxyl-containing aldehyde-ketone resin precursor; dissolving the hydroxyl-containing aldehyde-ketone resin precursor, adding a second hydroxyl monomer and a catalyst and heating the reaction, and removing impurities after cooling to obtain the modified aldehyde-ketone resin.

[0028] In some embodiments, in-situ hydroxyl groups are introduced during the polycondensation stage of the aldehyde-ketone resin to prepare a hydroxyl-containing aldehyde-ketone resin precursor. A second hydroxyl monomer is introduced during the curing of the hydroxyl-containing aldehyde-ketone resin precursor. The addition of hydroxyl monomers to introduce hydroxyl groups during both the in-situ synthesis and curing stages is beneficial to increasing the hydroxyl content in the finally synthesized modified aldehyde-ketone resin and improving the bonding between ABS and plastics.

[0029] In some embodiments, the amount of modified aldehyde-ketone resin added is 0.2% to 1% of the total mass of the substrate layer.

[0030] In some embodiments, the raw materials for preparing the substrate layer also include a compatibilizer. The compatibilizer helps to further improve the compatibility between the raw materials of the substrate layer and reduce delamination caused by high interfacial tension when the INS film is injection molded, thereby further improving the stability of the automotive interior INS film after injection molding.

[0031] In some embodiments, the raw materials for preparing the substrate layer also include antioxidants, such as phosphite antioxidant 168, phosphite antioxidant S-9228, and hindered phenolic antioxidant 1010. Antioxidants can prevent ABS from degrading due to oxidation during processing and use, extending the material's service life and maintaining its performance stability.

[0032] In some embodiments, the sum of the amounts of compatibilizer and antioxidant added to the substrate layer is 1% to 4%.

[0033] In some embodiments, an adhesive is applied to one side of the substrate layer to form an adhesive layer, which is then bonded and fixed to the patterned weather-resistant layer. Commonly used adhesives in the prior art include polyurethane adhesives, acrylic adhesives, and epoxy adhesives. Polyurethane adhesives are preferred in this application because they provide better adhesion to the substrate layer and result in a more stable bond.

[0034] Polyurethane adhesives can include thermoplastic polyurethane, polyurethane adhesives prepared from TDI (toluene diisocyanate), polyester polyols and trimethylolpropane, and anionic aliphatic polyether waterborne polyurethane PU-9519, among other common adhesives.

[0035] In some embodiments, the weather-resistant layer is PMMA or other materials with excellent anti-aging and environmental corrosion resistance. A pattern layer is provided on one side of the weather-resistant layer. In a preferred embodiment, the pattern layer is printed on one side of the weather-resistant layer by screen printing. The ink layer thickness of screen printing is much greater than that of other printing methods such as flatbed and gravure printing, resulting in unique visual and physical effects.

[0036] In some embodiments, the thickness of the weather-resistant layer is 20-100 μm, and the thickness of the substrate layer is 250-500 μm. A weather-resistant layer thickness less than 20 μm is prone to localized weakness and premature failure, while an excessively thick weather-resistant layer increases material costs and may cause wrinkles or cracks when laminated to curved or irregularly shaped substrates. The substrate layer needs to provide mechanical support, structural stability, and substrate adhesion. An excessively thin substrate layer is prone to insufficient strength, leading to the entire film breaking or insufficient rigidity causing cracking due to substrate deformation; an excessively thick substrate layer will cause a sharp decrease in the film's flexibility, making it unable to adapt to changes in substrate curvature, and material accumulation can easily lead to stress concentration due to thermal expansion and contraction, further increasing the risk of cracking.

[0037] This application also provides a method for preparing an automotive interior INS film, comprising the following preparation steps:

[0038] S1: Add aldehyde monomer and ketone monomer to a reaction vessel, add acid catalyst and heat to react for a period of time, add first hydroxyl monomer to continue the reaction, and obtain hydroxyl-containing aldehyde-ketone resin precursor; dissolve hydroxyl-containing aldehyde-ketone resin monomer, add second hydroxyl monomer and catalyst to heat to react, cool and remove impurities to obtain modified aldehyde-ketone resin.

[0039] S2: Mix ABS, modified aldehyde-ketone resin, compatibilizer, and antioxidant evenly, then add it to a twin-screw extruder for melt extrusion to obtain a substrate layer, and coat one side of the substrate layer with an adhesive.

[0040] S3: PMMA is melt-extruded in a twin-screw extruder to obtain a weather-resistant layer. A patterned layer is set on one side of the weather-resistant layer. The patterned layer is bonded to a substrate layer coated with adhesive. After the adhesive is cured, an automotive interior INS film is obtained.

[0041] The method for preparing automotive interior INS film in this application is simple, uses inexpensive and readily available raw materials, is not dangerous, has a high success rate and high yield of the target material, and is suitable for promotion in large-scale production.

[0042] In some embodiments, a patterned layer is formed on one side of the weather-resistant layer using one or more processes such as gravure printing, screen printing, vapor deposition, or sputtering.

[0043] This application also provides an injection molding process for an automotive interior INS film, comprising the following steps: heating and softening the aforementioned automotive interior INS film, using a film forming machine to adsorb and form the film, removing edge waste using laser or punching technology to obtain an inlaid film, placing the inlaid film in a mold cavity, injecting molten plastic, and allowing the plastic and the INS film to fuse and cross-link to form the automotive interior.

[0044] Example 1

[0045] The preparation of an INS film for automotive interior trim includes the following steps:

[0046] S1: Formaldehyde and cyclohexanone are added to a reaction vessel at a molar ratio of 1.2:1, along with 0.5% p-toluenesulfonic acid. The mixture is heated to 90-100 °C and refluxed for 3-5 hours to obtain a mixed solution. Pentaerythritol is added at a concentration of 8-15% of the mass of the mixed solution, and the reaction continues for 2 hours to generate a hydroxyl-containing aldehyde-ketone resin precursor. The hydroxyl-containing aldehyde-ketone resin precursor is dissolved in xylene, with a solid content of 40%. Subsequently, 8-15% polyethylene glycol and 0.3% stannous octoate are added, and the mixture is heated to 120-140 °C and reacted for 3-4 hours. After cooling, the catalyst is neutralized with dilute hydrochloric acid, washed three times with water, and the modified aldehyde-ketone resin is obtained after desolventizing under reduced pressure.

[0047] S2: ABS, modified aldehyde-ketone resin, styrene-maleic anhydride copolymer, and phosphite antioxidant 168 are uniformly mixed in a ratio of 97:1:1:1. The mixed raw materials are added to a twin-screw extruder for melt extrusion to obtain a substrate layer with a thickness of approximately 250 μm. One side of the substrate layer is coated with a commercially available methacrylate-based adhesive.

[0048] S3: PMMA is extruded in a twin-screw extruder to obtain a weather-resistant layer with a thickness of approximately 30 μm. A pattern layer is obtained by screen printing on one side of the weather-resistant layer. This pattern layer is then bonded to a substrate layer coated with adhesive. Subsequently, the bonded multilayer material is kept at 50 °C for 3 h to allow the adhesive to fully cure, resulting in an automotive interior INS film.

[0049] Example 2

[0050] Replace the adhesive in step S2 with thermoplastic polyurethane (TPU), and keep the other preparation steps the same as in Example 1.

[0051] Example 3

[0052] The raw material ratio of the substrate layer in step S2 was adjusted to 489:1:5:5, while the other preparation steps remained the same as those in Example 1.

[0053] Comparative Example 1

[0054] In step S1, no modified aldehyde-ketone resin is prepared. In step S2, the same mass of polyethylene glycol is used instead of the modified aldehyde-ketone resin. That is, in the process of preparing the substrate layer, ABS, polyethylene glycol, styrene-maleic anhydride copolymer, and phosphite antioxidant 168 are used in a raw material mass ratio of 97:1:1:1. Other preparation steps are consistent with the preparation steps in Example 1.

[0055] Comparative Example 2

[0056] In step S1, no modified aldehyde-ketone resin is prepared. In step S2, the same mass of unmodified aldehyde-ketone resin is used instead of the modified aldehyde-ketone resin. That is, in the process of preparing the substrate layer, ABS, aldehyde-ketone resin, styrene-maleic anhydride copolymer, and phosphite antioxidant 168 are used in a raw material mass ratio of 97:1:1:1. Other preparation steps are consistent with the preparation steps in Example 1.

[0057] Comparative Example 3

[0058] In step S1, no modified aldehyde-ketone resin is prepared. In step S2, during the preparation of the substrate layer, ABS, styrene-maleic anhydride copolymer, and phosphite antioxidant 168 are used in a raw material mass ratio of 98:1:1. Other preparation steps are consistent with the preparation steps in Example 1.

[0059] Injection molding process: The cut INS films prepared in the above embodiments and comparative examples are fixed on the fixture of the thermoforming machine. The film material is softened by heating plate, and the softened film is pressed into the preforming mold by vacuum adsorption. After cooling and shaping, a 3D molded film is obtained.

[0060] Performance testing

[0061] 1. Tensile strength test: The prepared INS film is rolled out along the spool direction, and stretched using a universal tensile testing machine until the film breaks. The stretching rate is 50 mm / min.

[0062] 2. Interlayer peel strength test: The pattern layer and adhesive layer are pre-peeled 50 mm apart along the length of the sample. The sample is clamped in the upper and lower clamps of the testing machine so that the longitudinal axis of the peeled part of the sample coincides with the line connecting the centers of the upper and lower clamps. Then the testing machine is turned on to stretch the sample.

[0063] 3. Peel strength test of molded film (INS film after injection molding): Peel the substrate layer and the injection molding layer 50 mm apart along the length of the sample. Clamp the sample in the upper and lower clamps of the testing machine so that the longitudinal axis of the peeled part of the sample coincides with the line connecting the centers of the upper and lower clamps. Then turn on the testing machine to stretch the sample.

[0064] 4. Heat aging resistance test method: Place the molded part in a 90℃ high temperature oven for 168 h, then place it at room temperature for 2 h, and then evaluate the changes in appearance and color.

[0065] O: After the test, the diaphragm surface was free of wrinkles; the appearance was free of cracks, breaks, whitening, peeling, and swelling; the color was free of fading and gloss changes; the surface was free of blurring, stickiness, fading after wiping, and defects such as stains on the effective surface.

[0066] ×: After the test, the membrane surface showed wrinkles or appearances such as cracks, breaks, whitening, peeling, and swelling; the color faded or the gloss changed; the surface became blurry, sticky, faded when wiped, and the effective surface showed stains and other defects.

[0067] The performance test results are recorded in Table 1 below.

[0068] Table 1 Performance test results of each embodiment and each comparative example

[0069]

[0070] Analysis of the performance test results in Table 1 clearly shows that the INS film prepared in this application exhibits excellent tensile strength, can withstand external tensile forces well without being easily damaged; at the same time, its heat aging resistance is also outstanding, and it can maintain a stable performance state even after long-term use in high-temperature environments, and is not prone to aging and deterioration.

[0071] In addition, the INS film also performs well in terms of bonding stability: not only are the layers of the film itself tightly bonded and not prone to detachment, ensuring the integrity of the overall structure of the film; but its bonding with the injection molded part is also extremely reliable, forming a stable whole and not prone to detachment.

[0072] This outstanding performance effectively extends the service life of automotive interior parts from multiple dimensions, reliably maintaining their integrity for 10 years without detachment, providing a strong guarantee for the long-term stable use of automotive interior parts.

[0073] Adding modified aldehyde-ketone resin to the substrate layer significantly increases the difficulty of separating the substrate layer from the injection molding material, and also increases the difficulty of interlayer peeling of the INS film. The choice of adhesive affects the interlayer peel strength of the INS film to a certain extent; polyurethane adhesives are more suitable for the substrate layer of this application, thus increasing the difficulty of interlayer peeling of the INS film.

[0074] The automotive interior INS film prepared in this application has high tensile strength, easily withstanding strong external tensile forces, and is not prone to breakage or damage during daily use. It also exhibits outstanding peel strength, with each layer of the film tightly bonded together, making peeling extremely difficult and ensuring the stability of the overall structure. Its connection to injection-molded parts is equally strong and reliable, with minimal separation, and it possesses good heat aging resistance, maintaining stable performance even under prolonged high-temperature environments.

[0075] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. An interior automotive (INS) film, characterized by, The weather layer, the pattern layer, the adhesive layer and the substrate layer are sequentially arranged, the side of the substrate layer away from the weather layer is suitable for fusion cross-linking forming with plastic, the raw material of the substrate layer comprises a modified aldehyde ketone resin, and the addition amount of the modified aldehyde ketone resin is 0.2% to 1% of the total mass of the raw material of the substrate layer; The raw material of the modified aldehyde ketone resin comprises an aldehyde monomer, a ketone monomer, a hydroxyl monomer and a catalyst; the hydroxyl monomer is any one or a combination of multiple of glycerol, pentaerythritol and polyethylene glycol; The preparation method of the modified aldehyde ketone resin comprises the following steps: the aldehyde monomer and the ketone monomer are added to a reaction container, an acid catalyst is added and heated for a period of time, the first hydroxyl monomer is added for continuous reaction, a hydroxyl-containing aldehyde ketone resin precursor is obtained, the hydroxyl-containing aldehyde ketone resin precursor is dissolved, the second hydroxyl monomer and the catalyst are added for heating reaction, and the modified aldehyde ketone resin is obtained after cooling and impurity removal.

2. The automotive interior (INS) film of claim 1, wherein The first hydroxyl monomer is pentaerythritol, and the second hydroxyl monomer is polyethylene glycol.

3. The automotive interior (INS) film of claim 1, wherein The raw material of the substrate layer further comprises a compatibilizer and an antioxidant, and the total addition amount of the compatibilizer and the antioxidant is 1% to 4% of the total mass of the substrate layer.

4. The automotive interior (INS) film of claim 1, wherein An adhesive is coated on one side of the substrate layer to form the adhesive layer, and the adhesive is a polyurethane-based adhesive.

5. The automotive interior (INS) film of claim 1, wherein The thickness of the weather layer is 20 to 100 mm, and the thickness of the substrate layer is 250 to 500 mm.

6. A method for producing an interior automotive (INS) film, characterized by, The preparation method comprises the following steps: S1: a modified aldehyde ketone resin is prepared by using an aldehyde monomer, a ketone monomer, a first hydroxyl monomer and a second hydroxyl monomer; S2: ABS, the modified aldehyde ketone resin, a compatibilizer and an antioxidant are uniformly mixed, and are fed into a double-screw extruder for melt extrusion to obtain a substrate layer, and an adhesive is coated on one side of the substrate layer; S3: PMMA is melt extruded in a double-screw extruder to obtain a weather layer, a pattern layer is arranged on one side of the weather layer, the pattern layer is connected to the substrate layer coated with the adhesive, and the automobile interior INS film is obtained after solidification; The preparation method of the modified aldehyde ketone resin comprises the following steps: the aldehyde monomer and the ketone monomer are added to a reaction container, an acid catalyst is added and heated for a period of time, the first hydroxyl monomer is added for continuous reaction, a hydroxyl-containing aldehyde ketone resin precursor is obtained, the hydroxyl-containing aldehyde ketone resin precursor is dissolved, the second hydroxyl monomer and the catalyst are added for heating reaction, and the modified aldehyde ketone resin is obtained after cooling and impurity removal.

7. The production method according to claim 6, wherein The pattern layer is formed on one side of the weather layer by using one or more of intaglio printing, screen printing, evaporation or sputtering process.

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