In-mold curved transfer printing method based on thermoset support and photo-solidification type

Abstract

The present application provides a kind of based on heat solid bearing and light solid type of in-mold curved surface transfer printing method, comprising the following steps: preparation modification film roll;The modification film roll is placed into vacuum curved surface hot pressing mould after being unwound, heated and softened to make the decoration film stretch and form curved surface decoration film piece;Plastic molten liquid and the plastic adhesive film of curved surface decoration film piece are bonded together, and form the precursor of decorative plastic structural member;The precursor of decorative plastic structural member is subjected to first photocuring operation, so that the bearing release hardened surface film realizes first photocuring crosslinking operation;The reverse topological pattern group of bearing release hardened surface film is exposed, then secondary photocuring operation is carried out, so that the bearing release hardened surface film realizes secondary photocuring crosslinking operation, and the finished product of decorative plastic structural member is obtained, so that the finished product of decorative plastic structural member prepared by the above method has higher structural function richness, higher three-dimensional function, and can reduce the problem of peeling, tearing and tearing mark.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface curve transfer printing of plastic parts, in particular to an in-mold curved surface transfer printing method based on heat solid bearing and light solid release. BACKGROUND

[0002] At present, the traditional appearance surface treatment industry of plastic structural parts (mobile phones, automotive interiors and household appliances) mainly realizes it through three mainstream schemes of spraying, PVD and printing, but all have the problems of large VOC emission, large emission of organic pollutants and environmental unfriendliness.

[0003] Taking the printing and spraying process as an example, the curved surface modification structure of the surface of the mobile phone back cover plastic part is made. First, the curved surface bearing body of the curved surface modification structure is pre-formed by injection molding, then the functional layer is formed by multiple glue brushing (printing or spraying), and each glue brushing needs to be solidified once to shape, to ensure the smooth progress of the next glue brushing process. The curved surface bearing body with the curved surface modification structure needs to be operated by CNC machining process to form a frame waste material edge and polishing operation, and finally the curved surface modification structure is formed. Finally, the mobile phone back cover plastic part is formed by in-mold injection molding of the plastic material to form the mobile phone back cover plastic part and the curved surface modification structure in one piece to obtain the finished product of the mobile phone back cover plastic part. However, the solidification operation of multiple glue brushing will cause the problem of coating brittleness, which will cause the problem of local cracking and wear of the curved surface modification structure in the in-mold injection molding operation and the CNC operation, and thus the whole piece will be scrapped. Secondly, the curved surface modification structure made by the traditional multiple glue brushing process has the problems of single surface treatment, poor three-dimensional function effect and poor function performance richness.

[0004] In view of the above problems, a new curved surface modification structure manufacturing process-in-mold vacuum curved surface transfer injection molding process (IMD, also known as in-mold decoration technology, paint-free technology, etc.) appears on the market. Its basic principle is: the printed Film thin film is made into a circulating drum roll and installed in the injection molding machine and injection mold, and is automatically moved like a label on the front mold surface. That is, it is called IMD (in-mold transfer injection). The other is that the Film thin film is printed and formed by a forming machine, and then placed in the injection mold to produce. That is, it is called IML (in-mold film injection). The Film can be divided into three layers: substrate (usually PET), ink layer (INK), and adhesive material (usually a special adhesive). After injection molding, the Film and the plastic are tightly combined and integrated by the adhesive, and the PET with a wear-resistant protective film on the outermost surface has the functions of wear resistance and scratch resistance, and the surface hardness can reach 3H, and it will become brighter with more touch. The injection molding material is mainly PC, PMMA, PBT, etc.

[0005] Such as Chinese invention patent 201310018766.8-a far infrared heating in-mold transfer injection molding method, discloses: (1) injection molding machine opens mold, film feeding machine transports film to the specified position between male mold and female mold; (2) the mechanical hand drives the far infrared heating plate to move to the specified heating position in front of the film, heats and softens the film; (3) the mold plate presses the film tightly on the female mold, the film and the female mold cavity form a sealed space, then vacuumize to adsorb the film on the surface of the female mold cavity; at the same time, the mechanical hand drives the suction cup to move to the specified position in front of the formed plastic part, adsorbs and takes away the plastic part, and returns to standby position; (4) the injection molding machine closes mold, injection molding, pressure maintaining, cooling, and enters the next transfer injection molding cycle.

[0006] Although the technical solution disclosed in the above patent can solve the cracking problem of the curved surface modification structure by softening and injection bonding to improve the good product, it does not solve the problem of functional richness of the curved surface modification structure, especially the problem of realizing the three-dimensional visual and tactile functions of the modified surface.

[0007] Such as Chinese invention patent application 201910448818.2-a plastic part in-mold embedded piece spraying process, discloses: step a: printing a predetermined texture pattern on the PET release film on the printing machine; step b: installing the printed PET release film on the heat transfer printing machine, heat transfer printing the 0.4mm thick ABS base film, so that the texture pattern is transferred to the ABS base film, and the PET release film is torn off; step c: forming the ABS base film into the surface shape of the plastic part to be printed by heat suction molding process, and punching off the excess edge to obtain the ABS film piece; step d: placing the ABS film piece in the injection mold, injecting the raw material, forming the plastic part with texture pattern and taking out; step e: spraying wear-resistant varnish on the plastic part with texture pattern and drying.

[0008] Although the technical solution disclosed in the above patent can also solve the cracking problem of the curved surface modification structure to improve the good product, it still does not solve the problem of functional richness of the curved surface modification structure, especially the problem of realizing the three-dimensional visual and tactile functions of the modified surface.

[0009] In addition, Chinese invention patent application 201910448818.2-a plastic part in-mold embedded piece spraying process also has the problem that after the pattern layer is heat-set, the crosslinking degree of the pattern layer is high, which causes the brittleness of the high molecular pattern layer to be also high. If there is still some peeling adhesion between the pattern layer and the release layer, it will affect the integrity of the high molecular pattern layer when the release layer is torn off based on the peeling adhesion, that is, there may be a problem of local tearing or tearing of the high molecular pattern layer.

[0010] Similarly, the photocurable transfer pattern layer also has the same problem, such as Chinese Patent 201480080939.1 - Photothermal curing coating composition, coating film forming method and water pressure.

[0011] Existing patent documents also include:

[0012] CN100424144C, 2008.10.08;

[0013] CN100424144C, 2008.10.08;

[0014] CN102649895A, 2012.08.29, etc. Summary of the Invention

[0015] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an in-mold curved surface transfer method based on thermosetting support and light-solid release, which has higher structural functional richness, higher three-dimensional stereoscopic function, and reduces the problem of peeling and tearing.

[0016] The object of the present invention is achieved through the following technical solutions:

[0017] An in-mold curved surface transfer method based on thermosetting support and light-curing release comprises the following steps:

[0018] Prepare a supporting base film, and coat a release film on the supporting base film; wherein the release film is made of polyetherimide;

[0019] A patterned three-dimensional groove group is formed on the release base film, and a carrier release hardening mask is coated on the release base film, wherein the carrier release hardening mask further forms an inverse three-dimensional pattern group within the patterned three-dimensional groove group; wherein the carrier release hardening mask is made of a light-heat dual-curing acrylic resin;

[0020] Coating N layers of functional film on the supporting release hardening film, wherein N ≥ 1;

[0021] Coating a plastic adhesive film on the N-layer functional film to obtain a decorative film, and rolling it up to obtain a modified film roll;

[0022] The decorative film roll is unwound and then placed into a vacuum curved surface hot pressing mold to heat and soften the decorative film. The concave mold of the vacuum curved surface hot pressing film is then vacuumed to make the curved surface of the decorative film adhere to the inner wall of the cavity of the concave mold, so that the decorative film is stretched to form a curved decorative film sheet;

[0023] The punch of the vacuum curved surface hot pressing film is controlled to move towards the recessed die, and plastic melt is injected into the filling gap between the recessed die and the punch through the glue injection channel of the punch, the plastic melt is bonded with the plastic adhesive film of the curved surface decoration film piece, and the supporting base film is torn off to form a decoration plastic structural part precursor;

[0024] The decoration plastic structural part precursor is subjected to a first photocuring operation to enable the supporting hardening surface film to realize a first photocuring crosslinking operation.

[0025] The release bottom film is torn off from the supporting hardening surface film to expose the reverse relief pattern group of the supporting hardening surface film, and then a second photocuring operation is performed to enable the supporting hardening surface film to realize a second photocuring crosslinking operation, thereby obtaining a finished decoration plastic structural part.

[0026] In one embodiment, the supporting base film is made of PET.

[0027] In one embodiment, the parameters of the first photocuring operation are as follows: UV irradiation energy 800-1200 mj / cm, wire speed 6-8 m / min, and UV irradiation time 2-5 S.

[0028] The parameters of the second photocuring operation are as follows: UV irradiation energy 1000-1800 mj / cm, wire speed 2-5 m / min, and UV irradiation time 3-10 S.

[0029] In one embodiment, the patterned relief groove group includes circular grooves, polygonal grooves, square grooves, and / or special-shaped grooves.

[0030] The reverse relief pattern group includes a plurality of relief pattern protrusions, and the thicknesses of the relief pattern protrusions are consistent or different.

[0031] In one embodiment, the heating and softening operation is specifically as follows:

[0032] A constant-temperature water vapor heating process is adopted to heat the decoration film to 120-150 degrees Celsius and continuously heat for 5-20 S to soften the decoration film, so that the decoration film has a ductile stretching function.

[0033] In one embodiment, the decoration film has a longitudinal-transverse stretching ratio of at least 20-30% at 120-150 degrees Celsius.

[0034] In one embodiment, the recessed die is provided with a heating device, a vacuum valve, and a pressure relief valve that respectively communicate with the cavity, and the vacuum valve is used to communicate with an external air compressor.

[0035] In one of the embodiments, the vacuum curved hot-pressing mold further comprises a pressing fixing plate, which is used to press and fix the decorative film before the concave mold of the vacuum curved hot-pressing mold is subjected to vacuumizing operation.

[0036] In one of the embodiments, a through channel is formed on the pressing fixing plate for the convex mold to pass through.

[0037] In one of the embodiments, the vacuumizing operation of the concave mold of the vacuum curved hot-pressing mold is specifically forming 0.1-1 Mpa within 5-10 S.

[0038] Compared with the prior art, the present application has at least the following advantages:

[0039] 1、The present application forms a patterned three-dimensional groove group on the release base film, and coats a load release hardening surface film. The light-heat dual-cured acrylic resin material fills the patterned three-dimensional groove group due to its flowability, so that the load release hardening surface film can form a reverse three-dimensional pattern group in the patterned three-dimensional groove group. Thus, after the load release hardening surface film is cured, the reverse three-dimensional pattern group can realize the effect of modifying the surface vision and three-dimensional tactile function. Further, the load release hardening surface film adopts a light-heat dual-cured acrylic resin material. When the load release hardening surface film is subjected to vacuum heating and curved surface extension and stretching, it has good toughness and certain mechanical strength based on the property of heat curing, which can provide good support and load bearing function for the N-layer functional film. After the UV light curing operation, the cross-linking degree of the load release hardening surface film is further strengthened, which can greatly reduce the peeling adhesion between the load release hardening surface film and the release base film. When the release base film is torn off from the load release hardening surface film, the peeling and tearing problems can be greatly reduced.

[0040] 2、The present application coats an N-layer functional film on the load release hardening surface film, which can realize the effect of higher structural function richness.

[0041] 3、The present application inserts a peeling operation between the two light curing operations of the surface plastic structure precursor, which can better realize the reverse three-dimensional pattern group with higher structural function richness and three-dimensional function, and also achieve good peeling release effect. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0043] Figure 1 The step flow chart of the in-mold curved surface transfer printing method based on heat-solid bearing and light-solid separation for an embodiment of the present application;

[0044] Figure 2 The manufacturing process flow chart of the decoration film for an embodiment of the present application;

[0045] Figures 3a to 3g The implementation process sequence flow chart of the in-mold curved surface transfer printing method based on heat-solid bearing and light-solid separation for an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to facilitate the understanding of the present application, the following will make a more comprehensive description of the present application with reference to the related drawings. The drawings show the preferred embodiments of the present application. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0047] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be limiting.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing the specific embodiments and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0049] The application provides an in-mold curved surface transfer printing method based on heat-solid bearing and light-solid release, which comprises the following steps: preparing a supporting base film and coating a release base film on the supporting base film; the material of the release base film is polyetherimide; forming a patterned three-dimensional groove group on the release base film, coating a bearing release hardening surface film on the release base film, and the bearing release hardening surface film also forms a reverse three-dimensional pattern group in the patterned three-dimensional groove group; the material of the bearing release hardening surface film is a light-heat dual-curing acrylic resin; coating N layers of functional films on the bearing release hardening surface film, wherein N≥1; coating a plastic adhesive film on the N layers of functional films to obtain a decorative film, and winding to obtain a modified film roll; unwinding the modified film roll and placing it into a vacuum curved surface hot pressing mold, heating and softening the decorative film, then the concave mold of the vacuum curved surface hot pressing film is operated by vacuumizing to make the curved surface of the decorative film adhere to the inner wall of the cavity of the concave mold, so that the decorative film is stretched to form a curved surface decorative film piece; the convex mold of the vacuum curved surface hot pressing film is controlled to move towards the concave mold, and plastic molten liquid is injected into the filling gap between the concave mold and the convex mold through the injection channel of the convex mold, the plastic molten liquid is bonded with the plastic adhesive film of the curved surface decorative film piece, and the supporting base film is torn off to form a surface plastic structural part precursor; the surface plastic structural part precursor is subjected to a first light curing operation to make the bearing release hardening surface film realize a first light curing crosslinking operation; the release base film is torn off from the bearing release hardening surface film to expose the reverse three-dimensional pattern group of the bearing release hardening surface film, and then a second light curing operation is performed to make the bearing release hardening surface film realize a second light curing crosslinking operation, thereby obtaining a surface plastic structural part finished product; thus, the surface plastic structural part finished product prepared by the above method has higher structural function richness and three-dimensional function, and can reduce the problem of peeling, tearing and tearing marks.

[0050] In order to better understand the in-mold curved surface transfer printing method based on heat-solid bearing and light-solid release of the application, the in-mold curved surface transfer printing method based on heat-solid bearing and light-solid release of the application is further explained as follows:

[0051] Please refer to Figure 1 The in-mold curved surface transfer printing method based on heat-solid bearing and light-solid release of an embodiment comprises the following steps:

[0052] Step S110: preparing a supporting base film 100a and coating a release base film 200a on the supporting base film 100a; the material of the release base film is polyetherimide (PEI).

[0053] Please refer to Figure 2, in order to better realize the continuous process of the subsequent curved surface transfer process, the supporting base film 100a is a linear long strip-shaped sheet structure, which can be wound into a film roll based on flexibility. In one embodiment, the material of the supporting base film is polyethylene terephthalate (PET or PEIT).

[0054] It should be noted that the above-mentioned PEI film material and PET film material are purchased from the PEI film material and PET film material sold by Guangdong Dongli New Material Technology Co., Ltd. Through actual production verification, both have good peeling performance in the subsequent transfer peeling process. Of course, the supporting base film is not limited to PET, and the release base film is not limited to PEI. As long as both have good peeling performance in the subsequent transfer peeling process, those skilled in the art can select other film materials produced by other manufacturers according to actual needs.

[0055] Step S120: forming a patterned three-dimensional groove group on the release base film 200a, and coating a bearing release hardening surface film 300a on the release base film 200a, the bearing release hardening surface film also forms a reverse three-dimensional pattern group in the patterned three-dimensional groove group; wherein the material of the bearing release hardening surface film is a photo-thermal dual-curing acrylic resin.

[0056] Please refer to Figure 2 By forming a patterned three-dimensional groove group on the release base film 200a and coating a bearing release hardening surface film 300a, the photo-thermal dual-curing acrylic resin material will fill the patterned three-dimensional groove group due to its flowability, which can make the bearing release hardening surface film form a reverse three-dimensional pattern group in the patterned three-dimensional groove group. In this way, when the bearing release hardening surface film is cured, it can realize the effect of modifying the surface vision and touch three-dimensional function through the reverse three-dimensional pattern group. Further, the bearing release hardening surface film adopts a photo-thermal dual-curing acrylic resin material, which has good toughness and certain mechanical strength based on the property of thermal curing when the bearing release hardening surface film is subjected to vacuum heating curved surface extension and stretching, thereby providing good support and bearing function for the N-layer functional film 400a. After the UV light curing post-operation, the cross-linking degree of the bearing release hardening surface film is further strengthened, which can greatly reduce the peeling adhesion between the bearing release hardening surface film and the release base film. When the release base film is torn off from the bearing release hardening surface film, the peeling and tearing problems can be greatly reduced.

[0057] In one of the embodiments, the stereoscopic groove pattern group includes circular grooves, polygonal grooves, square grooves and / or special-shaped grooves; the inverse stereoscopic pattern group includes a plurality of stereoscopic pattern protrusions, and the thickness of each stereoscopic pattern protrusion is consistent or different; of course, the person skilled in the art can also prepare the corresponding stereoscopic pattern according to the actual needs.

[0058] It should be noted that the above-mentioned light-thermal dual-curing acrylic resin is purchased from Huizhou Huian Poly-Sun Chemical Coating Co., Ltd., and of course, the person skilled in the art can also select other manufacturers' light-thermal dual-curing acrylic resin according to the actual needs.

[0059] Step S130: coating N layers of functional film 400a on the bearing release hardening surface film 300a, where N≥1.

[0060] Please refer to Figure 2 , by coating N layers of functional film 400a on the bearing release hardening surface film 300a, the N layers of functional film 400a can achieve the effect of higher structural functional richness. In one of the embodiments, the functional film is one layer, and the functional film is a mixture of pigment particle powder and resin coated on the bearing release hardening surface film 300a. Of course, the number of layers and the corresponding material of the functional film can also be flexibly selected and matched by the person skilled in the art according to the actual needs.

[0061] Step S140: coating a plastic adhesive film 500a on the N layers of functional film 400a to obtain a decorative film, and rolling to obtain a modified film roll.

[0062] Please refer to Figure 2 , by coating a plastic adhesive film 500a on the N layers of functional film 400a, the plastic adhesive film 500a can better protect the N layers of functional film, and at the same time, the plastic adhesive film 500a can better react and crosslink with the plastic melt liquid, strengthening the adhesion effect of the two.

[0063] It can be understood that for the surface plastic structure part precursor, each surface plastic structure part precursor exists independently, that is, a single surface plastic structure part precursor needs to be independently subjected to the in-mold curved surface transfer process, but in order to ensure that the entire above-mentioned in-mold curved surface transfer method based on heat-cured bearing and light-cured release can be continuously performed in an intermittent manner (simple transfer + injection molding is intermittent), but for a plurality of surface plastic structure part precursors, the construction operation is continuous, which means that the support base film must be continuous to ensure that the feeding can be operated in a continuous manner.

[0064] In order to ensure that the in-mold curved surface transfer printing method can realize intermittent continuous operation, and also realize higher structural function richness and three-dimensional function, and also ensure that the support base film is not affected when it is peeled off, in one embodiment, in steps S110-S140, the support base film 100a is a straight continuous film belt structure, and a plurality of independent transfer pieces are formed on the support base film 100a. The transfer pieces include a release base film sub-piece, a load release hardened surface film sub-piece, an N-layer functional film sub-piece, and a plastic adhesive film sub-piece arranged in sequence on the support base film 100a. There is a gap between each transfer piece, and there is no peeling or tearing adhesion between each transfer piece. The release base film 200a includes a plurality of discontinuous release base film sub-pieces. The load release hardened surface film 300a includes a plurality of discontinuous load release hardened surface film sub-pieces. The N-layer functional film 400a includes a plurality of discontinuous N-layer functional film sub-pieces. The plastic adhesive film 500a includes a plurality of discontinuous plastic adhesive film sub-pieces. Thus, due to the gap between each transfer piece, but also independently adhered to the support base film 100a, it can ensure that the in-mold curved surface transfer printing method can realize intermittent continuous operation, and also realize higher structural function richness and three-dimensional function, and also ensure that the support base film is not affected when it is peeled off.

[0065] Further, in steps S110-S140, the release base film, the load release hardened surface film, the N-layer functional film, and the plastic adhesive film are coated one after another using a continuous coating process. After obtaining the decorative film, a vertical glue scraping operation is used to sequentially scrape a plurality of empty glue separation gaps on the decorative film. The empty glue separation gap can expose both sides of the support base film 100a in the empty glue separation gap area, so as to obtain a plurality of transfer pieces. Each of the transfer pieces is separated by the empty glue separation gap. Thus, the entire glue coating process can be greatly simplified. Further, the width of the empty glue separation gap is 5-15 cm. Of course, the width of the empty glue separation gap can be flexibly selected by those skilled in the art according to actual needs.

[0066] The steps S150-S180 are explained in detail as follows, please refer to Figures 3a-3g for auxiliary explanation.

[0067] Step S150: After unwinding the decorative film roll, place it into a vacuum curved surface hot pressing mold to heat and soften the decorative film. Then, the concave mold of the vacuum curved surface hot pressing film is vacuumed to make the curved surface of the decorative film adhere to the inner wall of the cavity of the concave mold, so that the decorative film is stretched to form a curved decorative film sheet.

[0068] By heating and softening the decorative film (transfer sheet), the ductility and tensile properties of the decorative film can be improved. Then, the concave mold of the vacuum curved hot pressing film is used to form a negative pressure in the mold cavity by vacuuming. Based on the suction force generated by the negative pressure, the softened decorative film (transfer sheet) can be tightly attached to the inner wall of the mold cavity, so that the decorative film can be stretched to form a curved decorative film sheet. In this way, the curved surface shaping effect of the curved decorative film sheet can be achieved.

[0069] In one embodiment, the heating and softening operation is specifically: using a constant temperature water vapor heating process to heat the decorative film to 120-150 degrees Celsius, and continuously heating for 5-20 seconds to soften the decorative film, so that the decorative film has an elongation and stretching function; further, the decorative film has a longitudinal and transverse stretching ratio of at least 20-30% under the condition of 120-150 degrees Celsius.

[0070] In one embodiment, the die is provided with a heating device, and a vacuum valve and a pressure relief valve respectively connected to the cavity, and the vacuum valve is used to communicate with an external air compressor; further, the vacuum curved surface hot pressing mold also includes a holding and fixing plate, and the holding and fixing plate is used to hold and fix the decorative film before the die of the vacuum curved surface hot pressing film is vacuumed; further, the holding and fixing plate is provided with an avoidance channel for the punch to pass through; further, the vacuum operation of the die of the vacuum curved surface hot pressing film is specifically to form 0.1-1Mpa within 5-10S.

[0071] Step S160: Control the convex mold of the vacuum curved surface hot pressing film to move toward the concave mold, and inject plastic melt into the filling gap between the concave mold and the convex mold through the injection channel of the convex mold. The plastic melt is bonded to the plastic adhesive film of the curved surface decorative film, and the supporting base film is torn off to form a precursor of a decorative plastic structural part.

[0072] When the curved surface decorative film completes the curved surface shaping and shaping, the convex mold of the vacuum curved surface hot pressing film is controlled to move toward the concave mold to form a filling gap between the concave mold and the convex mold. The shape of the filling gap is the same as the structure of the plastic structural part formed by injection molding. When the plastic melt is injected into the filling gap between the concave mold and the convex mold through the injection channel of the convex mold, the plastic melt can fill the filling gap, thereby forming the plastic structural part. At the same time, the plastic melt and the plastic adhesive film of the curved surface decorative film undergo a cross-linking reaction or generate intermolecular force, so that the plastic structural part is completely bonded to the curved surface decorative film through the plastic adhesive film. When the supporting base film is torn off from the side of the release base film away from the pattern three-dimensional groove group, a decorative plastic structural part precursor can be obtained.

[0073] Step S170: subjecting the decorative plastic structural component precursor to a first light-curing operation, so that the supporting release hardening mask can achieve a first light-curing cross-linking operation.

[0074] It should be noted that in order to make the reverse-extruded three-dimensional pattern group on the carrier release hardening mask 300a directly exposed to the air (when the finished decorative plastic structural part is assembled with other parts to form a terminal product that can eventually come into direct contact with the user's hands or other parts), that is, the reverse-extruded three-dimensional pattern group on the carrier release hardening mask 300a can be directly perceived and touched, it is necessary to tear off the release base film 200a from the carrier release hardening mask. Since the carrier release hardening mask adopts a photothermal dual-curing acrylic resin material, and the material of the release base film is polyetherimide (Polyetherimide, abbreviated as PEI), the two materials are different, and no cross-linking reaction will occur at the contact interface, but there is an intermolecular force. When the carrier release hardening mask is still in the vacuum curved surface hot pressing mold The carrier release hardening mask has been heated and completed the heat curing operation, that is, the preliminary heat fixing operation has been completed, but the cross-linking degree of each monomer reaction in the carrier release hardening mask is low and is still in the early stage of curing. The mechanical strength and surface mechanical stiffness of the carrier release hardening mask still need to be strengthened. If the release base film is directly torn off from the carrier release hardening mask, there will be a strong intermolecular force between the carrier release hardening mask and the release base film, and the more actual contact area between the inverse three-dimensional pattern group and the pattern three-dimensional groove group will further strengthen the intermolecular force, which will cause the inverse three-dimensional pattern group on the carrier release hardening mask to be easily partially torn or torn off or damaged or cause tears and other peeling stickiness, coupled with the quality problems caused by the low curing strength of the carrier release hardening mask.

[0075] By subjecting the decorative plastic structural component precursor to a first photocuring operation, the curing strength of the supporting release hardening mask can be improved. When the release base film is torn off from the supporting release hardening mask through step S180, a better peeling and releasing effect can be achieved while achieving a higher structural function richness and a higher three-dimensional function of the reverse-topography three-dimensional pattern group.

[0076] Step S180: tear off the release base film from the carrier release hardening film to expose the reverse-extrusion three-dimensional pattern group of the carrier release hardening film, and then perform a secondary photocuring operation to enable the carrier release hardening film to achieve a secondary photocuring cross-linking operation to obtain a finished finished plastic structural part.

[0077] It should also be pointed out that since the first light curing operation cannot completely fix the supporting release hardening film of the decorative plastic structural component precursor, a final hardening molding process is required after the release base film is peeled off.

[0078] Of course, if a one-time light-curing process is used to tear off the release base film from the carrier release hardening mask, it will also cause quality problems. As we all know, when the carrier release hardening mask completes thermal curing + light curing and is fully cured, the carrier release hardening mask will also have a high brittleness problem when increasing the hardness, that is, the cross-linked product will also be accompanied by the problem of brittleness when the final hardness is achieved. If the release base film is torn off from the carrier release hardening mask at this time, the protrusions of each three-dimensional pattern in the reverse-topped three-dimensional pattern group will also easily cause the reverse-topped three-dimensional pattern group on the carrier release hardening mask to be easily partially torn or torn off or damaged or cause tear marks, etc., peeling stickiness, coupled with the quality problems caused by the high brittleness of the carrier release hardening mask. Simultaneously, the secondary light-curing operation after the release operation, because it is a deep cross-linking reaction, also has a certain self-healing effect on tiny tear marks.

[0079] Therefore, the above problems can be better avoided by performing double photocuring and adjusting the first photocuring degree to be weaker than the second photocuring degree, and performing a release operation between the two processes.

[0080] In one embodiment, the parameters of the first photocuring operation are: UV irradiation energy 800-1200mj / cm, line speed 6-8m / min, UV irradiation time 2-5S; the parameters of the second photocuring operation are: UV irradiation energy 1000-1800mj / cm, line speed 2-5m / min, UV irradiation time 3-10S, which can better adjust the intensity of the double photocuring operation to better adapt to the peeling and release operation.

[0081] In one of the embodiments, the thickness of the supporting base film is 70-100 microns (μm); the thickness of the release bottom film is 120-450 microns; the thickness of the bearing release hardening surface film is 10-50 microns, the thickness of the patterned three-dimensional groove group is 5-20 microns; the thickness of the N-layer functional film is 30-50 microns; the thickness of the plastic adhesive film is 10-15 microns.

[0082] In order to further reduce the tearing problem and improve the surface compensation self-healing performance, in the step S180, before the secondary photocuring operation is performed, a compensation repair layer is also sprayed on the exposed surface of the bearing release hardening surface film, the compensation repair layer is of the same material as the bearing release hardening surface film, and the thickness of the compensation repair layer is 0.5-1 micron. Thus, the tearing problem can be further reduced, and the surface compensation self-healing performance can be improved.

[0083] It should be noted that the bearing release hardening surface film is used to bear the reverse three-dimensional pattern group and the N-layer functional film, and the bearing release hardening surface film is also used to achieve the release and peeling effect with the release bottom film, and the bearing release hardening surface film is also used to achieve the hardening effect.

[0084] Compared with the prior art, the present application has at least the following advantages:

[0085] 1. In the present application, the patterned three-dimensional groove group is formed on the release bottom film, and the bearing release hardening surface film is coated. The light-thermal dual-cured acrylic resin material with flowability can be filled in the patterned three-dimensional groove group, so that the bearing release hardening surface film can form a reverse three-dimensional pattern group in the patterned three-dimensional groove group. Thus, when the bearing release hardening surface film is cured, the reverse three-dimensional pattern group can realize the effect of modifying the surface vision and three-dimensional tactile function. Further, the bearing release hardening surface film adopts the light-thermal dual-cured acrylic resin material. When the bearing release hardening surface film is subjected to vacuum heating and curved surface extension and stretching, based on the property of thermal curing, the bearing release hardening surface film can have better toughness and certain mechanical strength, which can support and bear the N-layer functional film. Then, after the UV photocuring post-operation is performed, the cross-linking degree of the bearing release hardening surface film can be further strengthened, which can greatly reduce the peeling adhesion between the bearing release hardening surface film and the release bottom film. When the release bottom film is torn off from the bearing release hardening surface film, the peeling and tearing problems can be greatly reduced.

[0086] 2. In the present application, the N-layer functional film is coated on the bearing release hardening surface film, and the N-layer functional film can realize the effect of higher structural function richness.

[0087] 3、The present application can better realize the reverse topographic pattern group, improve the structural function richness, and has higher three-dimensional function, and can also obtain good stripping and releasing effect under the premise of inserting stripping operation between twice light curing operation.

[0088] The following examples are listed, but it should be noted that the following examples do not exhaust all possible cases, and the materials used in the following examples are commercially available unless otherwise specified.

[0089] Example 1

[0090] 1、Purchase PEI film material and PET film material sold by Guangdong Dongli New Material Technology Co., Ltd.; purchase light-heat dual-curing acrylic resin (coated on PET film and preheated to form a film) sold by Huizhou Huizhong Poly-Sun Chemical Coating Co., Ltd., wherein the above-mentioned film material is a thin film material (10-500μm thick) that can be uniformly stretched (the longitudinal and transverse stretching ratio difference is about 20-30%) at high temperature (120-250 degrees).

[0091] 2、The coating resin with double curing conditions (heat curing and light curing two conditions) first maintains the toughness and workability of the related material coating under heat curing condition in the process, and then performs secondary light curing (that is, final curing) to complete the performance of the coating after completing all processes.

[0092] 3、The heating system supports the film and the coating on the film to complete the heating softening to present the ductility in the range of 5-20S, and can form a closed side (film and mold cavity single side) on one side of the mold, and can extract air to form a vacuum negative pressure value of 0.1-1Mpa within 5-10S, so that the material has ductility through the temperature softening in the previous step, and the thin film and the process layer on the carrier are uniformly and conformally attached to the surface of the cavity by using the pressure difference.

[0093] 4、Mold system, the mold function needs to have injection compression molding, vacuum storage pressure system, single cavity sealing system, rapid cycle heating system and PLC program control system, and comprehensively complete the sequential action and time node.

[0094] The whole process is as follows:

[0095] The finished appearance process is placed into the mold cavity side by a mechanical arm, fixed on one side of the film, and the mold is started to press the film and the single cavity to form a closed cavity. The sensor triggers a delayed vacuum preparation process, which is a heating process (120-150 degrees). The heating uses constant temperature steam, and the delay is 5-20 seconds. The film and the process layer on the film are softened at the preset softening point, forming a uniform extension material property. Under the control of the PLC node, the vacuum is started according to the sequence and time node. The flat film is adsorbed on one side of the cavity. Then the injection molding machine starts the whole process of injection compression molding. The product is taken out, the bottom film is peeled off, the process layer is transferred to the injection molded product, and the whole product is irradiated twice (first time off type + second time full solidification) UV (800-1800 mj, 3-10 s) to complete.

[0096] The in-mold curved surface transfer printing method based on heat-cured bearing and light-cured release of the above embodiment 1 has successfully carried out the cases of 3D curved surface appearance process integrated molding of mobile phone back cover, notebook A shell (outer shell) wire drawing, and woven texture integrated molding, as well as the pattern of the outer surface of the automobile interior part, and the IME process integration.

[0097] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for in-mold curved surface transfer based on thermosetting support and light-curing release, characterized in that: The steps include: Prepare a supporting base film, and coat a release film on the supporting base film; wherein the release film is made of polyetherimide; A patterned three-dimensional groove group is formed on the release base film, and a carrier release hardening mask is coated on the release base film, wherein the carrier release hardening mask further forms an inverse three-dimensional pattern group within the patterned three-dimensional groove group; wherein the carrier release hardening mask is made of a light-heat dual-curing acrylic resin; Coating N layers of functional film on the supporting release hardening film, wherein N ≥ 1; Coating a plastic adhesive film on the N-layer functional film to obtain a decorative film, and rolling it up to obtain a modified film roll; The decorative film roll is unwound and then placed into a vacuum curved surface hot pressing mold to heat and soften the decorative film. The concave mold of the vacuum curved surface hot pressing film is then vacuumed to make the curved surface of the decorative film adhere to the inner wall of the cavity of the concave mold, so that the decorative film is stretched to form a curved decorative film sheet; Controlling the convex mold of the vacuum curved surface hot pressing film to move toward the concave mold, and injecting plastic melt into the filling gap between the concave mold and the convex mold through the injection channel of the convex mold, the plastic melt is bonded to the plastic adhesive film of the curved surface decorative film, and the supporting base film is torn off to form a decorative plastic structural component precursor; The decorative plastic structural component precursor is subjected to a first light-curing operation to enable the support release hardening film to achieve a first light-curing cross-linking operation; The release base film is torn off from the carrier release hardening film to expose the reverse-extruded three-dimensional pattern group of the carrier release hardening film, and a compensation repair layer is sprayed on the surface of the exposed reverse-extruded three-dimensional pattern group of the carrier release hardening film. The compensation repair layer is made of the same material as the carrier release hardening film, and then a secondary photocuring operation is performed to enable the carrier release hardening film to achieve a secondary photocuring cross-linking operation to obtain a finished finished plastic structural part.

2. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The material of the supporting base film is PET.

3. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The parameters of the first light curing operation are: UV irradiation energy 800-1200mj / cm, line speed 6-8m / min, UV irradiation time 2-5s; The parameters of the secondary light curing operation are: UV irradiation energy 1000-1800 mj / cm, line speed 2-5 m / min, and UV irradiation time 3-10 s.

4. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The patterned three-dimensional groove group includes circular grooves and polygonal grooves; The reverse-rubbing three-dimensional pattern group includes a plurality of three-dimensional pattern protrusions, and the thickness of each of the three-dimensional pattern protrusions is consistent or different.

5. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The heating and softening operation is specifically as follows: A constant temperature steam heating process is used to heat the decorative film to 120-150 degrees Celsius and continuously heat for 5-20 seconds to soften the decorative film, so that the decorative film has the stretching function.

6. The method for in-mold curved surface transfer based on heat-setting support and light-setting release according to claim 5, characterized in that: The decorated film has a longitudinal and transverse stretching ratio of at least 20-30% under the condition of 120-150 degrees Celsius.

7. The in-mold curved surface transfer method based on thermal solidification and optical solidification release according to claim 1, characterized in that: The die is provided with a heating device, and a vacuum valve and a pressure relief valve respectively communicated with the cavity, and the vacuum valve is used to communicate with an external air compressor.

8. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The vacuum curved surface hot pressing mold further includes a holding and fixing plate, which is used to hold and fix the decorative film before the concave mold of the vacuum curved surface hot pressing film is vacuumed.

9. The in-mold curved surface transfer method based on heat-setting support and light-setting release according to claim 8, characterized in that: The pressing and fixing plate is provided with an avoidance channel for the punch to pass through.

10. The in-mold curved surface transfer method based on thermal solidification and light solidification release according to claim 1, characterized in that: The vacuum operation of the concave mold of the vacuum curved surface hot pressing film is specifically to form 0.1-1 MPa within 5-10 seconds.

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