Base-material-free foam adhesive tape and base-material-free composite adhesive tape

Abstract

The invention provides a substrate-free foam adhesive tape and a substrate-free composite adhesive tape. The invention relates to the technical field of foam adhesive tapes. The non-substrate foam tape comprises a grid release film, an adhesive layer and a foam layer which are sequentially stacked from bottom to top, wherein the foam layer has viscosity, and the foam layer is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5-50 parts of elastic particles, 0.35-1 part of a curing agent and 0.3 part of black paste. According to the foam tape, the acrylic base material, the elastic particles and the like are mixed according to a certain proportion, so that the prepared foam layer has viscidity and has relatively good adhesive force with an adhered layer, meanwhile, the modulus of the foam layer can meet requirements, and the foam layer and the whole foam tape have relatively good impact resistance and film printing resistance effects.

Description

Technical Field

[0001] The present invention relates to the technical field of foam tapes, and in particular to a substrate-free foam tape and a substrate-free composite tape. Background Art

[0002] The foam tapes currently on the market are stacked structures, which generally include a grid release film, a pressure-sensitive adhesive layer, a PET printed black film layer, a foam layer (non-sticky) and a black anti-stick coating. This type of foam tape is relatively thick. For example, a Chinese patent application (CN221971490U) discloses an OLED ultra-fine grid polypropylene foam tape, which includes: a grid light release film layer, an adhesive layer, a substrate layer and a polypropylene foam layer. The grid light release film layer, the adhesive layer, the substrate layer and the polypropylene foam layer are stacked in sequence from top to bottom. The grid light release film layer is a polyethylene terephthalate film layer, the adhesive layer is a modified polyacrylate pressure-sensitive adhesive layer, the substrate layer is a black antistatic printed film layer, and the polypropylene foam layer is a black closed-cell polypropylene foam layer. In addition to the necessary grid release film, pressure-sensitive adhesive and foam layer, this foam tape also adds other layer structures, resulting in a thicker foam tape.

[0003] Foam tape is widely used in electronic devices, such as mobile phones and laptops; taking mobile phones as an example, the fixed curved screen of a mobile phone generally includes, from top to bottom, a CG layer (glass cover), a functional layer (such as POL, BP, etc.), an integrated foam tape layer and a copper foil tape layer, wherein the copper foil tape layer includes an acrylic adhesive layer and a copper foil layer; structurally, the integrated foam tape layer links the functional layer and the copper foil tape layer, and the copper foil tape layer relies on its own acrylic adhesive layer to achieve bonding and fixation with the integrated foam tape layer.

[0004] In response to the market trend of thinner mobile phones, foam tapes are required to be thinner while meeting the requirements of impact resistance and other related performance. However, the design of existing integrated foam tapes cannot take into account both thickness and impact resistance at the same time, resulting in a significant decrease in impact resistance when the thickness is reduced. In addition, the modulus of existing integrated foam tapes is too large, resulting in indentations when they are compressed, and this indentation will affect the display effect of the mobile phone screen. Therefore, the problem of mold imprint on the mobile phone screen caused by the large modulus of integrated foam tapes is a common problem of integrated foam tapes on the current market.

[0005] In addition, the preparation method of the mesh release film on the current market generally includes first melting the PE particles, then coating on the surface of the substrate, embossing, cooling to form a mesh layer on the surface of the substrate, and then coating the surface of the mesh layer with a release agent to form a release layer on the mesh layer. For example, the Chinese patent application (CN 106273956A) discloses an embossed release film, including a substrate layer, a coating layer and a release layer; the coating layer is arranged on the substrate layer, and a texture is formed on the surface of the coating layer; the release layer is arranged on the coating layer and matches and fits with the texture. The coating layer is a polyethylene layer or a polypropylene layer.

[0006] This grid layer / laminated layer made of PE material (maximum temperature resistance 90°C) is not resistant to high temperatures. When the grid release film and pressure-sensitive adhesive are used to form a foam tape, since the general drying temperature of the adhesive is above 100°C, when the pressure-sensitive adhesive is coated on the release layer and dried, the grid embossing on the surface of the release film will be deformed, resulting in the grid-shaped exhaust grooves formed on the pressure-sensitive adhesive to be of different depths. Therefore, when the pressure-sensitive adhesive is attached to the surface of the attached object, the bubbles in the exhaust groove cannot be discharged and the exhaust groove cannot disappear within the preset time. This not only affects the production rhythm, but also affects the appearance and performance of the attached object, and also requires additional equipment to eliminate the bubbles, which undoubtedly increases production costs and production efficiency. Summary of the invention

[0007] The present disclosure provides a substrate-free foam tape and a substrate-free composite tape to at least solve one of the technical problems existing in the prior art.

[0008] According to a first aspect of the present disclosure, a substrate-free foam tape is provided, comprising a grid release film, an adhesive layer and a foam layer stacked in sequence from bottom to top; wherein the foam layer is sticky and is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 to 50 parts of elastic particles, 0.35 to 1 part of curing agent and 0.3 part of black paste.

[0009] In one embodiment, the foam layer is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 to 30 parts of elastic particles, 0.35 to 0.75 parts of curing agent and 0.3 parts of black paste; The acrylic base material has a solid content of 20% to 50%, a viscosity of 9000 to 16000 cps, a storage modulus of 10 to 35 Kpa, a glass transition temperature TG of -20°C to -35°C, a creep recovery rate of 90 to 100% at 25°C, and the material of the acrylic base material is polyacrylate; The particle size of the elastic particles is 5-50 μm, the compressive strength of the elastic particles is 150-250 MPa, and the density of the elastic particles is 0.3-0.8 g / cm 3 .

[0010] In one possible implementation manner, the thickness of the adhesive layer is 20-50 um, and the thickness of the foam layer is 50-110 um.

[0011] In one embodiment, the thickness of the adhesive layer is 30-50 μm, and the thickness of the foam layer is 80-100 μm.

[0012] In one embodiment, the grid release film includes a substrate layer, a resin grid layer and a release layer stacked in sequence from bottom to top; a grid structure is formed on the side of the resin grid layer in contact with the release layer, and the grid structure is composed of a plurality of uniformly arranged hexagonal grids connected to each other; the grooved convex strips formed between adjacent hexagonal grids intersect at the top corners of the hexagonal grids to form a node structure, and the circumscribed circle diameter of the node structure is 15~30μm.

[0013] In one possible implementation manner, the depth of the grooved convex strip is 5-10 μm, and the width of the grooved convex strip is 19-25 μm.

[0014] In one embodiment, the resin grid layer is configured to be able to remain unchanged at a temperature of at least 100°C, and the resin grid layer is formed by UV resin liquid photocuring, and the UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 3 to 12 parts of UV cross-linking agent, and 3 to 4 parts of UV initiator; wherein the UV cross-linking agent is a mixture of one or more of a bifunctional UV cross-linking agent, a trifunctional UV cross-linking agent, and a tetrafunctional UV cross-linking agent.

[0015] In one embodiment, the bifunctional UV crosslinking agent is a mixture of one or more of polyethylene glycol 400 diacrylate, 1,6-hexanediol diacrylate, and polyurethane modified diacrylate oligomer; The trifunctional UV crosslinking agent is a mixture of one or more of trimethylolpropane tris[3-(2-methylaziridinyl)propionate], trimethylolpropane triacrylate, and pentaerythritol triacrylate; The tetrafunctional UV crosslinking agent is a mixture of one or more of pentaerythritol tetraallyl ether and tetrafunctional polyester acrylate; The UV initiator is a mixture of one or more of 1-hydroxycyclohexyl phenyl ketone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthone and isopropylthioxanthone.

[0016] In one embodiment, the method for preparing the grid release film comprises: The UV resin liquid is transferred and coated onto the surface of the substrate layer by an anilox roller, and then UV initial curing is performed to initially form a resin grid layer with a grid structure on the surface of the substrate layer. The UV exposure during UV initial curing is 500~2000 mj / cm 2 ; The substrate layer with the resin grid layer formed on the surface is subjected to UV secondary curing molding; wherein the UV exposure during UV secondary curing is 500~2000 mj / cm 2 ; A release agent is coated on the surface of the grid structure of the resin grid layer to form a release layer.

[0017] According to a second aspect of the present disclosure, there is provided a substrate-free composite tape, comprising the substrate-free foam tape and a pasted layer, wherein the pasted layer is bonded to the foam layer.

[0018] In one possible implementation manner, the laminated layer is a copper foil layer.

[0019] Compared with the prior art, the advantages of the present application are: 1) The present application mixes the acrylic base material and elastic particles in a certain proportion, so that the prepared foam layer has stickiness, has good adhesion to the attached layer, and can make the modulus of the foam layer meet the requirements, so that the foam layer and the entire foam tape have good impact resistance and anti-film printing effect. Therefore, the foam tape of the present application can not only omit the setting of the PET printed black film layer and the anti-sticking coating, but also omit the setting of the acrylic adhesive layer in the copper foil tape layer, which meets the requirements of thinning, impact resistance, and anti-film printing, while reducing the production cost.

[0020] 2) The number of projects for the substrate-free foam tape of this application is significantly reduced, and the production is reduced from 5 projects to 3 projects. At the same time, the number of projects for the laminated layer is reduced, and the gluing project for the laminated layer is directly removed, which effectively improves the yield rate and makes it more cost-effective.

[0021] 3) When the size of the node structure on the grid structure of the grid release film of the present application is limited to the range of 15~30μm, it can be combined with the width and depth of the groove convex strips so that the bubbles in the exhaust groove on the pressure-sensitive adhesive can be discharged within a preset time, and the exhaust groove can also disappear within a preset time.

[0022] 4) The resin mesh layer of the present application is formed by UV resin liquid light curing, so that the resin mesh layer is resistant to high temperature (it can be kept at 90-150°C without deformation, and can even remain unchanged at above 150°C). Therefore, when the adhesive is coated on the mesh release film and dried to form a pressure-sensitive adhesive layer, it can ensure that the entire mesh release film does not deform, and the mesh structure does not deform, thereby ensuring that the depth of the exhaust groove formed on the surface of the pressure-sensitive adhesive is consistent, and ensuring the exhaust stability and disappearance of the exhaust groove.

[0023] 5) The present application adopts a coating process, which has more advantages in controlling dimensions and appearance than the existing conventional film laminating process. The UV curing embossing is faster and more thorough, and the depth and width data of the formed grid structure are more stable.

[0024] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. Brief Description of the Drawings

[0025] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features, and advantages of the exemplary embodiments of the present disclosure will become easily understood. In the drawings, several embodiments of the present disclosure are shown in an exemplary rather than restrictive manner, where: In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0026] Figure 1 Shows a schematic structural diagram of a substrate-free foam tape according to an embodiment of the present disclosure; Figure 2 Shows a schematic structural diagram of a substrate-free composite tape according to an embodiment of the present disclosure; Figure 3 Shows a schematic structural diagram of a foam layer according to an embodiment of the present disclosure (where Figure 3 Figure (a) is a schematic structural diagram of the foam layer, Figure 3 and Figure (b) is a schematic diagram of the impact force transmission direction when the foam layer is subjected to a point impact force); Figure 4 Shows a schematic structural diagram of a grid release film and a pressure-sensitive adhesive layer according to an embodiment of the present disclosure; Figure 5 Shows a top view of a grid release film according to an embodiment of the present disclosure under a microscope; Figure 6 Shows a schematic diagram of a node structure formed by the intersection of the pressure grooves and ridges of a grid structure according to an embodiment of the present disclosure; Figure 7 Shows a node structure formed by the intersection of the pressure grooves and ridges in the first case according to an embodiment of the present disclosure; Figure 8 Shows a node structure formed by the intersection of the pressure grooves and ridges in the second case according to an embodiment of the present disclosure; Fig. 9 Shows a node structure formed by the intersection of the pressure grooves and ridges in the third case according to an embodiment of the present disclosure; Fig.10 Shows an arrangement schematic diagram of a grid structure composed of hexagonal grids and a grid structure composed of quadrilateral grids according to an embodiment of the present disclosure.

[0027] Figure numbers: 1-grid release film, 2-pressure-sensitive adhesive layer, 3-foam layer, 4-attached layer, 11-substrate layer, 12-resin grid layer, 13-grid structure, 14-release layer, 21-second planar adhesive layer, 22-microstructure adhesive layer, 121-first planar adhesive layer, 131-hexagonal grid, 132-grooved convex strips, 133-node structure, 221-exhaust grooves. DETAILED DESCRIPTION

[0028] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0029] According to the first aspect of the present disclosure, Figure 1 As shown, the present invention provides a substrate-free foam tape (referred to as "foam tape", the same below), comprising a grid release film 1, an adhesive layer and a foam layer 3 stacked in sequence from bottom to top; wherein the foam layer 3 is sticky, and the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 to 50 parts of elastic particles, 0.35 to 0.1 parts of curing agent and 0.3 parts of black paste.

[0030] For example, the adhesive layer is a pressure-sensitive adhesive layer 2 , and preferably, the pressure-sensitive adhesive layer 2 is an acrylic pressure-sensitive adhesive layer.

[0031] Preferably, the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5-30 parts of elastic particles, 0.35-0.75 parts of curing agent and 0.3 parts of black paste. Exemplarily, the amount of elastic particles added is 5 parts, 15 parts, and 30 parts. The amount of curing agent added is 0.35 parts, 0.55 parts, and 0.75 parts.

[0032] For example, the main indicator of foam tape's anti-film printing is the CFD (compression rebound force) indicator. The smaller the CFD value, the better the anti-film printing effect. Preferably, 25% CFD≤400Kpa, 50% CFD≤900Kpa.

[0033] More preferably, 25% CFD<120Kpa, 50% CFD<450Kpa, the anti-film printing effect will be more ideal; the main indicators of impact resistance are point impact and surface impact absorption rate, the higher the absorption rate, the better the impact resistance.

[0034] For example, the acrylic base material is colorless and transparent, the solid content of the acrylic base material is 20~50%, the viscosity is 9000~16000cps, the storage modulus of the acrylic base material is 10-35Kpa, the glass transition temperature TG is -20℃~ -35℃, the creep recovery rate at 25℃ is 90-100%, and the material of the acrylic base material is polyacrylate.

[0035] The compressive strength of the elastic particles is 150-250Mpa, the particle size is 5~50μm, the elastic particles are hollow inside, and the density of the elastic particles is 0.3~0.8g / cm 3 For example, the elastic particles are microsphere particles, which are white fluid powders, spherical in shape, with a particle size of 5 to 15 μm and a density of 0.58 to 0.62 g / cm 3 , compressive strength is 193 MPa, pH value is 8~9.5, water content is ≤0.5%, floating rate is ≥96%, and the main component is silicon dioxide.

[0036] Exemplarily, the curing agent is aliphatic isocyanate trimer, and the model / manufacturer of the black paste used is Xiyan C629.

[0037] The properties of the elastic particles and acrylic base material are listed in Table 1 below.

[0038] Table 1 Properties of elastic particles and acrylic base materials

[0039] In an optional solution, the thickness of the adhesive layer is 20-50 μm, and the thickness of the foam layer 3 is 50-110 μm. Preferably, the thickness of the adhesive layer is 30-50 μm, and the thickness of the foam layer 3 is 80-100 μm.

[0040] The number of processes for the substrate-free foam tape of this embodiment is significantly reduced, and the production is reduced from 5 processes to 3 processes. At the same time, the number of processes for the laminated layer is reduced, and the gluing process for the laminated layer is directly removed, which effectively improves the yield rate and makes it more cost-effective.

[0041] Specifically, in this embodiment, first, the PET printed black film layer (referred to as PET layer, also known as printed film) and the anti-sticking coating commonly used in the current foam tape are removed, and only the necessary pressure-sensitive adhesive layer and foam layer are retained, thereby meeting the application end's demand for lightweight design. Among them, the removal of the PET printed black film layer can reduce the thickness by 5%, and greatly reduce the overall modulus of the foam tape, and improve the anti-film printing performance. This is because the modulus of the PET printed black film layer is thousands of times that of the foam layer and the pressure-sensitive adhesive layer, so removing the PET layer can greatly reduce the overall modulus. Secondly, the present application designs the foam layer 3 to be sticky, which not only reduces the thickness of the anti-sticking coating, but also reduces the thickness of the acrylic adhesive layer in the attached layer (such as the copper foil tape layer), so that the foam layer is directly bonded and fixed to the copper foil layer. This design reduces the thickness by 11% in total.

[0042] However, there are technical difficulties in the design: First, the PET printed black film layer and the anti-stick coating are removed at the same time, so that the pressure-sensitive adhesive layer 2 and the foam layer 3 are in direct contact; therefore, we must not only consider the thinning of the thickness, but also the feasibility of the process, as well as the compatibility and adhesion between the foam layer 3 and the pressure-sensitive adhesive layer 2. At the same time, it is also necessary to consider whether the foam layer 3 and the pressure-sensitive adhesive layer 2 will affect each other and cause performance variation. Second, not only the impact resistance of the foam layer 3 must be considered, but also the bonding strength between the foam layer 3 and the attached layer 4 (such as the copper foil layer). These two designs are somewhat contradictory, so the research and development of the base material of the foam layer 3 is very difficult.

[0043] After a lot of creative experiments, we mixed the acrylic base material and elastic particles in a certain proportion, so that the prepared foam layer 3 has stickiness, has good adhesion with the attached layer 4 (such as copper foil layer), and can make the modulus of the foam layer 3 meet the requirements, so that the foam layer 3 and the entire foam tape have good impact resistance and anti-film printing effect. Therefore, the foam tape of the present application can not only omit the setting of the PET printed black film layer and the anti-sticking coating, but also omit the setting of the acrylic adhesive layer in the copper foil tape layer, which meets the requirements of thinning, impact resistance, and anti-film printing, while reducing the production cost.

[0044] Among them, the modulus of the acrylic base material and the elastic particles were screened, and it was found that in terms of impact resistance, in the substrate-free foam tape of this embodiment, a very low modulus acrylic base material and hollow elastic particles with higher hardness were used, and the mixture was mixed at a higher ratio of elastic particle concentration. The foam layer 3 formed would form a support frame on the surface of the pressure-sensitive adhesive layer 2, and the elastic particles filled it, which played a role in alleviating the impact force. Among them, due to the use of a low-modulus acrylic base material, the modulus of the foam layer is lower, and after being subjected to the same impact force, the deformation will be faster and the deformation will be greater. The high-concentration, high-hardness hollow elastic particles can diffuse the impact force absorbed by the base material to the plane laterally through mutual collision, thereby reducing the impact on the functional layer below, such as Figure 3 Figure (a) Figure 3 As shown in Figure (b), the foam layer 3 of the present application has better impact absorption when the thickness is relatively thin, which can be compared to the foam layer and spring in a Simmons mattress.

[0045] In terms of anti-film printing, in the foam layer 3 of the present application, the acrylic base material with low modulus is used. After being pressed down the same distance, the pressure transmitted to the functional layer will be less than that of the acrylic base material with high modulus. This is also the reason why the thinned substrate-free foam tape of the present application has excellent performance in anti-film printing.

[0046] In summary, the innovative structural design of this application effectively reduces the thickness of the product while improving the anti-film printing performance, and also reduces costs and improves the yield rate of the application end, making the product more cost-effective. This application solves the two market demands of thickness reduction and anti-film printing at the same time through the innovative design of acrylic base material and elastic particles.

[0047] In some embodiments, Figure 1 , Figure 3-6 As shown, the grid release film 1 includes a substrate layer 11, a resin grid layer 12 and a release layer 14 stacked in sequence from bottom to top; a grid structure 13 is formed on the side of the resin grid layer 12 that contacts the release layer, and the grid structure 13 is composed of a plurality of uniformly arranged hexagonal grids 131 connected to each other, and grooved ridges 132 are formed between adjacent hexagonal grids, and the grooved ridges 132 formed between adjacent hexagonal grids intersect at the top corners of the hexagonal grids to form a node structure 133, and the diameter of the circumscribed circle of the node structure 133 is 15-30 μm, the depth of the grooved ridge 132 is 5-10 μm, and the width of the grooved ridge 132 is 19-25 μm.

[0048] like Figure 6 As shown. The grooved convex strips 132 between three adjacent hexagonal grids 131 meet at one of the vertex positions of the hexagonal grids to form a node structure 133, and the shape of the node structure is a triangle. When the size of the node structure is slightly smaller, such as Figure 7As shown, near the intersection, the two side edges of the groove convex strip 132 gradually shrink inward, and the two side edges are in an outward convex arc shape, so that the width of the groove convex strip gradually decreases, so that the three groove convex strips intersect to form a node structure 133.

[0049] Alternatively, it can be near the intersection, such as Figure 8 As shown, the two side edges of the groove pressing convex strip 132 gradually expand outwards, and the two side edges are generally in the shape of an inwardly concave arc, so that the width of the groove pressing convex strip gradually increases, so that the three groove pressing convex strips intersect to form a node structure 133.

[0050] Or, it can also be, Fig. 9 As shown, the width of the groove ridge 132 does not vary.

[0051] In summary, the groove convex strip 132 is close to the node structure 133, and a transition section is formed between the groove convex strip 132 and the node structure 133. Towards the direction close to the node structure 133, the width of the transition section gradually decreases, or the width of the transition section gradually increases, or the width of the transition section remains unchanged.

[0052] The above mentioned need to be adjusted accordingly according to the width of the groove convex strip and the size of the node structure.

[0053] Since the resin grid layer is formed by embossing transfer with anilox roller, a corresponding texture pattern can be pre-engraved on the surface of the anilox roller according to the shape and size of the exhaust grooves on the surface of the pressure-sensitive adhesive layer 2. The structure and shape of the texture pattern correspond to the grid structure.

[0054] Exemplarily, the depth of the grooved convex strip 132 can be 5μm, 8μm, or 10μm. The width of the grooved convex strip 132 can be 19μm, 22μm, or 25μm. The diameter of the circumscribed circle of the node structure 133 can be 15μm, 20μm, 25μm, or 30μm. In the present application, the so-called "circumscribed circle of the node structure" is the circumscribed circle of the virtual triangle formed by the lines connecting the vertices of each adjacent hexagon at the intersection. That is, the circumscribed circle of the virtual triangle formed by the wide sides (in the width direction) of the adjacent grooved convex strips at the intersection.

[0055] For example, Figure 6 As shown, the hexagonal grid in this embodiment may be a regular hexagon, and the side length of the hexagonal grid is 160-180 um.

[0056] For example, the material of the substrate layer 11 is one of PET, PI, BOPP, paper and PEEK. The material of the release layer 14 is solvent silicone oil or solvent-free silicone oil. The material of the resin grid layer 12 is high temperature resistant resin.

[0057] The thickness of the substrate layer 11 is 25-188 μm, the thickness of the resin mesh layer 12 is 15-100 μm, and the thickness of the release layer 14 is 0.5-1 μm.

[0058] We found that when the grid structure 13 is composed of a plurality of uniformly arranged hexagonal grids 131 connected to each other, the corresponding exhaust grooves 221 formed on the surface of the pressure-sensitive adhesive layer 2 are hexagonal exhaust grooves, and these hexagonal exhaust grooves are interconnected through exhaust nodes (when the node structure of the grid release film is transferred to the pressure-sensitive adhesive layer, exhaust nodes will be formed on the surface of the pressure-sensitive adhesive layer), thereby forming a grid shape. Under the same conditions, the number of hexagonal exhaust grooves and exhaust nodes are more than the current conventional quadrilateral exhaust grooves, and the more exhaust grooves and exhaust nodes, the better the exhaust effect, so the hexagonal exhaust grooves are better than the quadrilateral exhaust grooves in exhaust effect.

[0059] Therefore, this embodiment takes the grid structure 13 composed of hexagonal grids 131 as an example, and compares it with the conventional grid structure composed of quadrilateral grids in the market. Fig.10 As shown, the hexagonal grid-shaped exhaust grooves and quadrilateral grid-shaped exhaust grooves formed by their transfer to the surface of the pressure-sensitive adhesive layer 2 are analyzed. We select hexagonal exhaust grooves and quadrilateral exhaust grooves with the same conditions and the same area for arrangement. The results show that the rule of increasing exhaust nodes is (the number and exhaust node rule of quadrilateral exhaust grooves and hexagonal exhaust grooves as shown in Table 2): 1) When the number of quadrilateral exhaust grooves increases to an odd number, one exhaust node is added. When the number of quadrilateral exhaust grooves increases to an even number, two exhaust nodes are added. 2) As long as the number of hexagonal exhaust grooves increases by one, the corresponding exhaust nodes will increase by two. Therefore, the grid release film needs to choose a polygonal graphic, and the following two points need to be achieved: First, it can be densely arranged without blank areas, and the exhaust grooves form a continuous channel without breakpoints. Second, the number of exhaust grooves and exhaust nodes should be as many as possible. Therefore, the hexagonal exhaust groove is the best choice that meets these two points. Correspondingly, on the grid release film, the grid unit that constitutes the grid structure is the hexagonal grid as the best choice.

[0060] Table 2 The number and exhaust node rules of conventional quadrilateral exhaust slots and hexagonal exhaust slots of the present application

[0061] Specifically, the side of the resin mesh layer 12 in contact with the release layer 14 is a mesh structure 13 in a mesh shape, and the mesh structure 13 is composed of a plurality of uniformly arranged hexagonal meshes 131 connected to each other, and these hexagonal meshes are substantially arranged and connected to each other in the order of hexagonal shapes through grooved convex strips 132, so that adjacent hexagonal meshes share one grooved convex strip 132. The grooved convex strips between adjacent hexagonal meshes intersect at the vertex positions of the hexagons to form a node structure 133, and these grooved convex strips are connected to each other through the node structure. Therefore, when the pressure-sensitive adhesive layer 2 is stacked on the surface of the grid release film 1, these grooved convex strips 132 on the grid structure can form corresponding grid-like hexagonal exhaust grooves on the surface of the pressure-sensitive adhesive layer 2. These exhaust grooves also intersect at the apex corners of the hexagon to form exhaust nodes, so that after the grid release film is peeled off from the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer as a whole has the grid-like hexagonal exhaust grooves, so that when the pressure-sensitive adhesive layer is attached to the object, the bubbles in the exhaust grooves can be quickly discharged and the exhaust grooves can be made to disappear within a preset time.

[0062] In the present application, the grid structure 13 on the grid release film is composed of hexagonal grids 131 as units connected to each other. We found that, compared with the quadrilateral grid structure on the conventional release film, under the same conditions, when the number of sides of the polygonal grid is more, the number of exhaust nodes of the exhaust groove formed on the surface of the pressure-sensitive adhesive layer 2 is more, and the exhaust effect is positively correlated. Since the grid structure 13 is formed by transferring the resin liquid to the surface of the substrate layer using an anilox roller, it is necessary to first engrave a pattern corresponding to the grid structure 13 on the anilox roller. Considering the difficulty of implementing the pattern on the anilox roller, it is preferred to use a hexagonal grid.

[0063] When the exhaust grooves 221 formed on the surface of the pressure-sensitive adhesive layer 2 are attached to the attached object, most of the bubbles in the exhaust grooves are gathered at the exhaust node positions. However, after the mesh release film on the market is stacked with the pressure-sensitive adhesive, the exhaust grooves on the surface of the pressure-sensitive adhesive cannot be discharged when the exhaust grooves are actually attached to the attached object, and the exhaust grooves cannot disappear within the preset time. After a lot of research and experiments, we found that when the size of the node structure 133 on the grid structure 13 of the mesh release film (i.e., the diameter of the circumscribed circle of the node structure) is limited to the range of 15~30μm, it can be matched with the width (19~25μm) and depth (5~10μm) of the groove convex strip 132, so that the bubbles in the exhaust grooves 221 on the pressure-sensitive adhesive layer 2 can be quickly discharged, and the exhaust grooves 221 can also disappear within the preset time.

[0064] In addition, when the grid release film 1 is used in conjunction with the pressure-sensitive adhesive layer 2 to prepare the foam tape, a release layer 14 is first coated on the grid structure of the resin grid layer, thereby ensuring that the grid release film 1 can be peeled off from the pressure-sensitive adhesive layer 2. The thickness of the release layer 14 is generally 0.5~1μm, and compared with the depth of the grid structure, the thickness of the release layer 14 can be ignored. Therefore, when the grid release film 1 composed of the substrate layer, the resin grid layer and the release layer is stacked with the pressure-sensitive adhesive layer 2, the size of the grid structure can be completely transferred to the pressure-sensitive adhesive layer 2, so that the corresponding grid-shaped hexagonal exhaust grooves are formed on the surface of the pressure-sensitive adhesive layer 2. In addition, the depth, width and exhaust node size of the hexagonal exhaust grooves on the pressure-sensitive adhesive layer are comparable to the depth of the groove convex strips 132 of the grid structure 13, the width of the groove convex strips 132 and the size of the node structure 133.

[0065] Among them, we also found through research that the exhaust property and vanishability of the exhaust groove 221 on the surface of the pressure-sensitive adhesive layer 2 are a set of paradoxes, and the two are contradictory. If you want to ensure the exhaust property of the exhaust groove 221, you need to increase the physical size of the exhaust groove (such as the depth of the exhaust groove and the width of the exhaust groove), but the increase in the physical size of the exhaust groove 221 makes the vanishability of the exhaust groove difficult to increase by multiples, which means that the vanishability of the exhaust groove cannot be achieved. If you want to ensure the vanishability of the exhaust groove, you need to appropriately reduce the physical size of the exhaust groove, such as reducing the width of the exhaust groove and the depth of the exhaust groove, but the bubbles in the exhaust groove cannot be discharged smoothly. Therefore, it is necessary to find a balance between exhaust property and vanishability to ensure that these two properties can be achieved at the same time. In addition, since most of the bubbles in the exhaust grooves gather at the exhaust node positions and are difficult to exhaust, we have found through a large number of orthogonal experiments that, under the premise that the diameter of the circumscribed circle of the node structure 133 of the grid release film is 15~30μm, when the depth of the groove ridge 132 on the grid release film is 5~10μm and the width of the groove ridge 132 is 19~25μm, the exhaust groove 221 transferred on the surface of the pressure-sensitive adhesive layer 2 can be quickly exhausted when the exhaust grooves 221 are attached to the adhered objects, whether it is the bubbles in the channel of the exhaust grooves or the bubbles in the exhaust nodes where the ends of the exhaust grooves meet, and the exhaust grooves are also guaranteed to disappear within a preset time.

[0066] For example, Figure 4As shown, the resin grid layer 12 includes a grid structure 13 and a first planar adhesive layer 121, and the first planar adhesive layer 121 is arranged between the grid structure 13 and the substrate layer 11. The grid structure 13 is arranged on the side of the first planar adhesive layer 121 away from the substrate layer 11, and the grid structure 13 protrudes from the first planar adhesive layer 121. The pressure-sensitive adhesive layer 2 includes a microstructure adhesive layer 22 and a second planar adhesive layer 21, and the second planar adhesive layer 21 is located between the microstructure adhesive layer 22 and the foam layer 3. The microstructure adhesive layer 22 is interlocked with the grid structure 13 and the release layer 14 thereon, and exhaust grooves 221 are formed on the microstructure adhesive layer 22, and the shape of these exhaust grooves 221 is hexagonal, and the hexagonal exhaust grooves 221 are interconnected to form a grid shape. Therefore, when the pressure-sensitive adhesive is coated on the release surface of the release layer 14 on the grid structure to form the pressure-sensitive adhesive layer 2, these groove convex strips on the grid structure are transferred to the surface of the pressure-sensitive adhesive layer, thereby forming a grid-shaped exhaust groove 221 on the surface of the pressure-sensitive adhesive layer 2.

[0067] In some embodiments, the resin grid layer is configured to remain unchanged at a temperature of at least 100°C, and the resin grid layer 12 is formed by photocuring of UV resin liquid, and the UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 3 to 12 parts (phr) of UV cross-linking agent, and 3 to 4 parts of UV initiator; wherein the UV cross-linking agent is a mixture of one or more of a bifunctional UV cross-linking agent, a trifunctional UV cross-linking agent, and a tetrafunctional UV cross-linking agent.

[0068] For example, the UV glue may be epoxy UV glue, and the available models include but are not limited to: Loctite EA3335, TSBD2640, and Loctite 3523.

[0069] The UV initiator can initiate a polymerization reaction when the material is exposed to ultraviolet light. Exemplarily, the UV initiator is a mixture of one or more of 1-hydroxycyclohexyl phenyl ketone (PI-184), diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 2-isopropylthioxanthone, and isopropylthioxanthone (ITX105).

[0070] Bifunctional UV crosslinkers include, but are not limited to, polyethylene glycol 400 diacrylate (PEG400DA), 1,6-hexanediol diacrylate (HDDA, also known as "1,6-hexanediol diacrylate"), and polyurethane-modified diacrylate oligomer (DOUBLEMER® 5222).

[0071] Trifunctional UV crosslinkers include, but are not limited to, trimethylolpropane tris[3-(2-methylaziridinyl) propionate] (TTMAP), trimethylolpropane triacrylate (TMPTA), and pentaerythritol triacrylate (PETA).

[0072] The tetrafunctional UV crosslinking agent includes, but is not limited to, pentaerythritoltetraallyl ether and tetrafunctional polyester acrylate (ETERCURE 6325-100).

[0073] In this embodiment, the resin mesh layer is formed by UV resin liquid light curing, so that the resin mesh layer is resistant to high temperature (the temperature is maintained at 90-150°C without deformation, and can even remain unchanged at above 150°C). Therefore, when the adhesive (i.e., pressure-sensitive adhesive) is coated on the surface of the release layer of the mesh release film and dried to form a pressure-sensitive adhesive layer, it can ensure that the entire mesh release film is not deformed, and the mesh structure is not deformed, thereby ensuring that the depth of the exhaust groove formed on the surface of the pressure-sensitive adhesive layer is consistent, and ensuring the exhaust stability and disappearance of the exhaust groove.

[0074] For example, in this embodiment, the grid release film is specifically prepared by the following method: comprising: The UV resin liquid is transferred and coated onto the surface of the substrate layer by an anilox roller, and then UV initial curing is performed to initially form a resin grid layer with a grid structure on the surface of the substrate layer. The UV exposure during UV initial curing is 500~2000 mj / cm 2 ; The substrate layer with the resin grid layer formed on the surface is subjected to UV secondary curing molding; wherein the UV exposure during UV secondary curing is 500~2000 mj / cm 2 ; A release agent is coated on the surface of the grid structure of the resin grid layer to form a release layer.

[0075] In this embodiment, UV resin liquid is added to the anilox roller, and the anilox roller transfers the UV resin liquid to the surface of the substrate layer in the form of embossing, and then UV primary curing is performed. After UV primary curing, the resin grid layer is stripped from the anilox roller, and a resin grid layer with a grid structure is formed on the surface of the substrate layer. Then, UV secondary curing is further performed to form the resin grid layer on the surface of the substrate layer, further ensuring a stable connection between the resin grid layer and the substrate layer. It can be seen from this that the materials of the resin grid layer and the grid structure formed on one side are not only the same, but they are also one-step, integrated, and photocured on the surface of the substrate layer. Then, a release agent (such as silicone oil) is applied to the surface of the grid structure to form a release layer.

[0076] In this embodiment, the coating process is used, which has more advantages in controlling the size and appearance than the conventional laminating process. The UV curing embossing molding is faster and more thorough, and the depth and width data of the formed grid structure are more stable.

[0077] According to the second aspect of the present disclosure, Figure 2As shown, the present invention provides a substrate-free composite tape, including a foam tape, and also including a pasted layer 4, wherein the pasted layer 4 is bonded to the foam layer 3. Exemplarily, the pasted layer 4 can be a copper foil layer, an aluminum foil layer, a ceramic layer, etc., which can be bonded to the foam layer and is suitable for the tape field. More preferably, the pasted layer 4 is a copper foil layer. The composite tape structure having the foam tape of the present application can also achieve the thinning effect while satisfying the impact resistance and anti-film printing effect of the composite tape. In addition, when the substrate-free composite tape of the present application is actually pasted to the object to be pasted, the bubbles between the pressure-sensitive adhesive layer and the surface of the object to be pasted can be quickly discharged, and the exhaust grooves on the surface of the pressure-sensitive adhesive layer can also disappear within a preset time.

[0078] The foam tape of the present application can be sold separately as an independent product, and of course it can also be bonded with the attached layer to form a composite tape for sale. Among them, when the foam tape is sold separately as an independent product, it is necessary to pre-attach release paper on the foam layer 3. When it is needed to be applied to the application end (such as the fixed curved screen of a mobile phone), the release paper is first removed, and then the foam layer 3 and the attached layer 4 (such as the copper foil layer) are bonded and fixed.

[0079] The present application is further described in detail below with reference to specific embodiments: Example 1 1): A substrate-free foam tape, comprising a grid release film 1, a pressure-sensitive adhesive layer 2 and a foam layer 3 stacked in sequence from bottom to top; wherein the foam layer 3 is sticky, and the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 parts of elastic particles, 0.35 parts of curing agent, and 0.3 parts of black paste.

[0080] The pressure-sensitive adhesive layer 2 is an acrylic pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer 2 is 30 μm, the thickness of the foam layer 3 is 100 μm, and the total thickness of the pressure-sensitive adhesive layer 2 and the foam layer 3 is 130 μm.

[0081] Among them, the material of the acrylic base material is polyacrylate, with a solid content of 20%, a storage modulus of 10KPa, a glass transition temperature Tg of -20℃, a viscosity of 9000cps, and a creep recovery rate of 90% at 25℃; The elastic particles are white fluid powder, spherical in shape, with a particle size of 5~15μm, a compressive strength of 193MPa, and a density of 0.58~0.62 g / cm 3 , pH value is 8~9.5, water content ≤0.5%, floating rate ≥96%, and the main component is silicon dioxide.

[0082] The curing agent is an aliphatic isocyanate trimer.

[0083] The grid release film 1 comprises a substrate layer 11, a resin grid layer 12 and a release layer 14 stacked in sequence from bottom to top, and a grid structure 13 is formed on the side of the resin grid layer 12 contacting the release layer 14. The grid structure 13 is composed of a plurality of uniformly arranged hexagonal grids 131 connected to each other, and groove convex strips 132 are formed between adjacent hexagonal grids. The groove convex strips 132 between adjacent hexagonal grids intersect at the vertex position of the hexagonal grids to form a node structure 133. The shape of the node structure is a triangle, the diameter of the circumscribed circle of the node structure is 15-30 μm, the depth of the groove convex strip 132 is 5-10 μm, and the width of the groove convex strip 132 is 19-25 μm.

[0084] The material of the substrate layer 11 is PET, and the resin mesh layer 12 is formed by UV resin liquid photocuring, and the UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 10 parts of bifunctional UV crosslinking agent, and 3 parts of UV initiator. Among them, the bifunctional UV crosslinking agent is polyethylene glycol 400 diacrylate, and the UV initiator is 1-hydroxycyclohexyl phenyl ketone (PI-184).

[0085] 2): A method for preparing a substrate-free foam tape: comprising the following steps: Step 1: Preparation of the grid release film 1: specifically comprising: Step 1-1): UV resin liquid is transferred and coated onto the surface of the substrate layer 11 by an anilox roller, and then UV initial curing is performed, thereby initially forming a resin grid layer 12 having a grid structure 13 on the surface of the substrate layer. The UV exposure during UV initial curing is 500 mj / cm 2 ; Step 1-2): The substrate layer with the resin grid layer formed on the surface is subjected to UV secondary curing molding; wherein the UV exposure during UV secondary curing is 500 mj / cm 2 ; Step 1-3): A release agent is coated on the surface of the grid structure of the resin grid layer to form a release layer 14.

[0086] Step 2: Preparation of the pressure-sensitive adhesive layer 2: A pressure-sensitive adhesive is coated on the surface of the release layer facing away from the substrate layer, thereby forming a pressure-sensitive adhesive layer on the surface of the release layer.

[0087] Step 3: prepare a foam layer 3, and then bond the foam layer and the pressure-sensitive adhesive layer together to finally obtain a substrate-free foam tape.

[0088] Example 2 The second embodiment is substantially the same as the first embodiment, except that the UV resin solution includes the following raw materials in parts by weight: 100 parts of UV glue, 6 parts of bifunctional UV crosslinking agent, 2 parts of trifunctional UV crosslinking agent, and 4 parts of UV initiator. The UV exposure during the UV primary curing and UV secondary curing is 1000 mj / cm 2 The bifunctional UV crosslinker is 1,6-hexanediol diacrylate, the trifunctional UV crosslinker is trimethylolpropane triacrylate, and the UV initiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0089] Example 3 The present embodiment 3 is substantially the same as the embodiment 1, except that the UV resin solution comprises the following raw materials in parts by weight: 100 parts of UV glue, 5 parts of trifunctional UV crosslinking agent, and 3 parts of UV initiator. The UV exposure during UV primary curing and UV secondary curing is 1500 mj / cm 2 The trifunctional UV crosslinker is pentaerythritol triacrylate, and the UV initiator is isopropylthioxanthone ITX1105.

[0090] Example 4 This embodiment 4 is substantially the same as embodiment 1, except that the UV resin solution includes the following raw materials in parts by weight: 100 parts of UV glue, 3 parts of a tetrafunctional UV crosslinking agent, and 4 parts of a UV initiator. The UV exposure during the UV primary curing and UV secondary curing is 1000 mj / cm 2 The tetrafunctional UV crosslinker is pentaerythritol tetraallyl ether, and the UV initiator is 1-hydroxycyclohexyl phenyl ketone (PI-184).

[0091] Example 5 This embodiment 5 is substantially the same as embodiment 1, except that the UV resin solution includes the following raw materials in parts by weight: 100 parts of UV glue, 5 parts of bifunctional UV crosslinking agent, 4 parts of trifunctional UV crosslinking agent, 3 parts of tetrafunctional UV crosslinking agent, and 3 parts of UV initiator. The UV exposure during UV primary curing and UV secondary curing is 2000 mj / cm 2 The bifunctional UV crosslinker is polyurethane modified diacrylate oligomer DOUBLEMER® 5222, the trifunctional UV crosslinker is pentaerythritol triacrylate, the tetrafunctional UV crosslinker is tetrafunctional polyester acrylate ETERCURE 6325-100, and the UV initiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0092] Example 6 This embodiment 6 is substantially the same as the embodiment 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35°C, a viscosity of 12000 cps, and a creep recovery rate of 94% at 25°C.

[0093] Example 7 This embodiment 7 is substantially the same as embodiment 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 30 parts of elastic particles, 0.75 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 50%, a storage modulus of 35 KPa, a glass transition temperature Tg of -20°C, a viscosity of 16000 cps, and a creep recovery rate of 98% at 25°C.

[0094] Example 8 This embodiment 8 is substantially the same as embodiment 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 40 parts of elastic particles, 1 part of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35°C, a viscosity of 12000 cps, and a creep recovery rate of 94% at 25°C.

[0095] Example 9 This embodiment 9 is substantially the same as the embodiment 1, except that: the thickness of the adhesive layer is 20 μm, and the thickness of the foam layer is 110 μm; the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35°C, a viscosity of 12000 cps, and a creep recovery rate of 94% at 25°C.

[0096] Example 10 This embodiment 10 is substantially the same as embodiment 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35°C, a viscosity of 12000 cps, and a creep recovery rate of 94% at 25°C.

[0097] Embodiment 11 Example 11 is generally the same as Example 1, except that: the thickness of the adhesive layer is 50 μm, and the thickness of the foam layer is 80 μm; the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12,000 cps, and a creep recovery rate of 94% at 25 °C.

[0098] Comparative Example 1 Comparative Example 1 is generally the same as Example 1, except that: the addition amount of elastic particles is 0 part.

[0099] Relevant performance tests Next, relevant performance tests were carried out on the substrate-free foam tapes prepared in each example.

[0100] I): The composition components of the resin mesh layer in Examples 1-5 are listed in Table 3.

[0101] Table 3 Composition components of the resin mesh layer

[0102] And the heat resistance experiment was carried out on the mesh release films prepared in Examples 1-5, and the results are shown in Table 4: Table 4 Heat resistance test results of the mesh release films in Examples 1-5

[0103] It can be concluded from Table 4 that the resin mesh layer and the entire mesh release film prepared by using the UV resin liquid of the present application can be deformed and high-temperature resistant at 90~150 °C. Thus, it is ensured that the exhaust grooves formed on the pressure-sensitive adhesive layer have the same depth, and the exhaustibility and disappearability of the exhaust grooves are ensured.

[0104] II): Correlation experiment on the physical dimensions of the pressing rib 132 and the node structure 133 dimensions of the mesh structure 13 of the mesh release film and the exhaustibility and disappearability of the exhaust grooves of the pressure-sensitive adhesive layer 2.

[0105] Next, we further discuss the correlation between the physical size (such as depth and width) of the groove convex strip 132 and the size of the node structure 133 on the air venting and vanishing properties of the air vent formed on the pressure-sensitive adhesive layer: taking the circumscribed circle diameter of the node structure 133, the depth of the groove convex strip 132 and the width of the groove convex strip 132 as variables, and other conditions being the same (such as using a hexagonal grid, the composition and thickness of the UV resin grid layer are the same, the substrate layer material is the same, etc.), to discuss the correlation between the physical size of the groove convex strip and the air venting and vanishing properties of the air vent of the pressure-sensitive adhesive layer, that is, to conduct an orthogonal correlation experiment (the influencing factor table is shown in Table 5), and the orthogonal experiment results are shown in Table 6: Table 5 Influencing factors and solutions

[0106] Table 6 Orthogonal experiment results

[0107] Note: Both the exhaust effect and the disappearing effect need to be made into tape products for performance testing. This orthogonal experiment is conducted by making the same single-sided disappearing textured tape (i.e., a single-sided mesh tape, at least including a mesh release film, a pressure-sensitive adhesive and a substrate layer stacked in sequence from bottom to top) for comparative evaluation. The evaluation criteria are shown in Table 7: Table 7 Evaluation criteria for the venting effect and disappearing effect of the venting groove of the pressure-sensitive adhesive layer

[0108] Note: The mesh pattern in Table 7 refers to the grid-like exhaust grooves.

[0109] Among them, (1): Exhaust test: Cut the produced single-sided disappearing reticulated tape into a size of 50mm×50mm in an environment with a temperature of 23±2℃ and a humidity of 65±5%. Then stick the adhesive layer of the tape on the glass plate, and press the bubble in the middle of the tape clockwise with your finger to check its exhaust speed and whether it can be exhausted.

[0110] (2): Disappearance test: Cut the prepared single-sided disappearing patterned tape into a size of 50×50mm. Tear off the grid release film on the tape, and stick the grid adhesive surface flat on the white glass; roll back and forth with a 2kg rubber roller 3 times (speed of 25mm / sec). Place the pasted sample at room temperature, use LED light and a magnifying glass to observe the disappearance of the pattern every 1hr, and record the disappearance time (observe all positions, and record the disappearance time after confirming that the pattern has completely disappeared).

[0111] From Table 6, it can be concluded that the exhaust effect and disappearance effect of the experimental groups 3 / 4 / 6 / 7 / 8 / 11 / 12 / 14 / 16 / 18 / 19 / 22 meet the requirements, especially the exhaust effect and disappearance effect of the experimental groups 7 / 14 / 18 are the best. Therefore, through Tables 5-7, we can get that when the diameter of the circumscribed circle of the node structure 133 of the grid release film is 15~30μm, the depth of the groove convex strip 132 is 5~10μm, and the width of the groove convex strip 132 is 19~25μm, the exhaust groove 221 on the surface of the pressure-sensitive adhesive layer 2 can be discharged when the object is attached, and the exhaust groove can also be guaranteed to disappear completely.

[0112] III): The elastic modulus, impact resistance and CFD of the foam tapes prepared in Example 1 and Examples 6-8, as well as the adhesion between the adhesive layer and the foam layer, and the adhesion between the foam layer and the copper foil layer (i.e., the laminated layer 4) were tested. The results are shown in Table 8 below: Among them, the point impact absorption rate test includes: 1) taking the sample to be tested, the size is 75mm×75mm, and sticking it on a 0.7mm thick 75mm×75mm glass plate; 2) taking a 4.3g steel ball, adjusting the height of the steel ball to 10.1cm, the steel ball is magnetically adsorbed, and the platform below the steel ball is stainless steel with a sensor to test the initial impact force. In order to reduce the equipment error, it is necessary to test 3 groups of point impact blank tests as a control group to ensure that the values ​​of the 3 groups of blank tests are similar and take the average value to finally get the initial impact force; 3) After the blank test is completed, the glass plate with the sample to be tested is placed with the glass side facing down and the foam side facing up in the middle of the stainless steel platform to test the point impact force. After 3 tests, 3 groups of point impact force values ​​are obtained and the average value is taken to get the impact force II; 4) According to the formula: ((initial impact force-impact force II) / initial impact force)×100%, the point impact absorption rate is calculated.

[0113] Adhesion test: Take the adhesion test between the adhesive layer and the foam layer as an example. The adhesive layer of the foam tape is attached to the test board. After rolling with a roller for 3 times, the traction tape is evenly attached to the non-test surface of the foam layer. Then the test board is fixed on the mobile fixture of the tensile machine, and the traction tape is fixed on the fixed fixture. The test board is peeled off at an angle of 180° and a speed of 300mm / min to test the adhesion between the adhesive layer and the foam layer.

[0114] The adhesion between the foam layer and the copper foil layer is also tested by referring to the above method.

[0115] CFD test: The foam tape with the grid release film removed is folded to about 10 mm, and then placed on the compression platform to test the compression rebound force at 25% and 50% compression ratios.

[0116] Table 8 Performance test results of foam tapes prepared in various embodiments and comparative examples

[0117] It can be concluded from Table 8 that the foam tapes prepared in this embodiment 1 and embodiments 6-8 have good point impact absorption rate, CFD value and elastic modulus. And the adhesion between the prepared foam layer and the copper foil layer is above 1500 g / 25mm. In particular, the adhesion between the foam layer and the copper foil layer of embodiments 1 and 6-7 is above 3000g / 25mm, which meets the user's optimal standard. Among them, the foam layer in the foam tape prepared in embodiment 8 is much smaller than that in other embodiments in terms of adhesion. Although its point impact absorption rate value is the highest, considering the adhesion, point impact absorption rate and CFD value comprehensively, we found that the foam tape composed of 100 parts of acrylic base material, 5 to 30 parts of elastic particles, 0.35 to 0.75 parts of curing agent and 0.3 parts of black paste can better meet the production requirements. More preferably, considering the three indicators of adhesion, point impact absorption rate and CFD value comprehensively, we further found that the comprehensive index of the foam tape prepared in embodiment 6 reaches the best.

[0118] IV): In this application, the thickness of the pressure-sensitive adhesive layer 2 and the foam layer 3 can be combined in various thicknesses according to user requirements. The distribution of the thickness of the pressure-sensitive adhesive layer and the foam layer is determined experimentally based on performance requirements. Taking the foam tape with a total of 130μm of pressure-sensitive adhesive layer and foam layer as an example, the foam tape prepared with pressure-sensitive adhesive layers and foam layers of different thicknesses is further discussed. The corresponding adhesion between the pressure-sensitive adhesive layer and the foam layer, the adhesion between the foam layer and the layer to be adhered (copper foil layer), the point impact absorption rate of the foam tape, CFD, the reticulation disappearance of the grid release film and other experimental data are shown in Table 9 below: Table 9 Experimental data of foam tape

[0119] It can be concluded from Table 9 that in the foam tapes prepared in Examples 9-11, the difference in adhesion between the foam layer and the copper foil layer (laminated layer) is small, and is much greater than the optimal standard of 2000 g / 25mm, and all meet the user's optimal standard. The adhesion between the adhesive layer and the foam layer varies slightly due to the thickness of the adhesive layer, but can also meet the user's optimal standard. The foam tapes prepared in Examples 9-11 have slightly smaller differences in point impact absorption rate, but the difference in CFD value is large, among which the CFD value of Examples 10-11 is better, especially the CFD value of Example 11 is the best, the most ideal in terms of anti-film printing effect, and the reticulation disappearance time is also much lower than that of Example 9. Taking into account the point impact absorption rate, CFD and reticulation disappearance time, the foam tapes prepared in Examples 10-11 have better performance. Therefore, when the thickness of the adhesive layer is 30-50 μm and the thickness of the foam layer is 80-100 μm, the reticulation on the adhesive layer of the prepared foam tape can disappear quickly when it is attached to the object, and can completely disappear in 2-3 hours at the minimum. The foam tape also has good impact resistance and anti-film printing effects.

[0120] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0121] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The above is only a specific implementation method of the present disclosure, but the scope of protection of the present disclosure is not limited to this. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be covered within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be based on the scope of protection of the claims.

Claims

1. A substrate-free foam tape, characterized in that: It includes a grid release film, a glue layer and a foam layer stacked in sequence from bottom to top; wherein the foam layer is sticky and is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 to 50 parts of elastic particles, 0.35 to 1 part of curing agent and 0.3 part of black paste.

2. The substrate-free foam tape according to claim 1, characterized in that: The foam layer is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5-30 parts of elastic particles, 0.35-0.75 parts of curing agent and 0.3 parts of black paste; The acrylic base material has a solid content of 20% to 50%, a viscosity of 9000 to 16000 cps, a storage modulus of 10 to 35 Kpa, a glass transition temperature TG of -20°C to -35°C, a creep recovery rate of 90 to 100% at 25°C, and the material of the acrylic base material is polyacrylate; The particle size of the elastic particles is 5-50 μm, the compressive strength of the elastic particles is 150-250 MPa, and the density of the elastic particles is 0.3-0.8 g / cm 3 .

3. The substrate-free foam tape according to claim 1, characterized in that: The thickness of the adhesive layer is 20-50um, and the thickness of the foam layer is 50-110um.

4. The substrate-free foam tape according to claim 3, characterized in that: The thickness of the adhesive layer is 30-50 μm, and the thickness of the foam layer is 80-100 μm.

5. The substrate-free foam tape according to claim 1, characterized in that: The grid release film comprises a substrate layer, a resin grid layer and a release layer stacked in sequence from bottom to top; a grid structure is formed on the side of the resin grid layer in contact with the release layer, and the grid structure is composed of a plurality of hexagonal grids connected to each other; the grooved convex strips formed between adjacent hexagonal grids intersect at the top corners of the hexagonal grids to form a node structure, and the diameter of the circumscribed circle of the node structure is 15 to 30 μm.

6. The substrate-free foam tape according to claim 5, characterized in that: The depth of the groove convex strip is 5-10 μm, and the width of the groove convex strip is 19-25 μm.

7. The substrate-free foam tape according to claim 5, characterized in that: The resin grid layer is configured to be able to remain unchanged at a temperature of at least 100°C. The resin grid layer is formed by photocuring with UV resin liquid, and the UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 3 to 12 parts of UV cross-linking agent, and 3 to 4 parts of UV initiator; wherein the UV cross-linking agent is a mixture of one or more of a bifunctional UV cross-linking agent, a trifunctional UV cross-linking agent, and a tetrafunctional UV cross-linking agent.

8. The substrate-free foam tape according to claim 7, characterized in that: The bifunctional UV crosslinking agent is a mixture of one or more of polyethylene glycol 400 diacrylate, 1,6-hexanediol diacrylate, and polyurethane modified diacrylate oligomer; The trifunctional UV crosslinking agent is a mixture of one or more of trimethylolpropane tris[3-(2-methylaziridinyl)propionate], trimethylolpropane triacrylate, and pentaerythritol triacrylate; The tetrafunctional UV crosslinking agent is a mixture of one or more of pentaerythritol tetraallyl ether and tetrafunctional polyester acrylate; The UV initiator is a mixture of one or more of 1-hydroxycyclohexyl phenyl ketone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthone and isopropylthioxanthone.

9. The substrate-free foam tape according to claim 7 or 8, characterized in that: The preparation method of the grid release film comprises: The UV resin liquid is transferred and coated onto the surface of the substrate layer by an anilox roller, and then UV initial curing is performed to initially form a resin grid layer with a grid structure on the surface of the substrate layer. The UV exposure during UV initial curing is 500~2000 mj / cm 2 ; The substrate layer with the resin grid layer formed on the surface is subjected to UV secondary curing molding; wherein the UV exposure during UV secondary curing is 500~2000 mj / cm 2 ; A release agent is coated on the surface of the grid structure of the resin grid layer to form a release layer.

10. A substrate-free composite tape, characterized in that: The substrate-free foam tape comprises the substrate-free foam tape according to any one of claims 1 to 9, and further comprises a pasted layer, wherein the pasted layer is bonded to the foam layer.

11. The substrate-free composite tape according to claim 10, characterized in that: The attached layer is a copper foil layer.

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