CN115157806B

CN115157806B - Digital printing plate and preparation method thereof

Info

Publication number: CN115157806B
Application number: CN202210721301.8A
Authority: CN
Inventors: 唐道远
Original assignee: Anhui Sentai Wpc Technology Floor Co ltd
Current assignee: Anhui Sentai Wpc Technology Floor Co ltd
Priority date: 2022-06-24
Filing date: 2022-06-24
Publication date: 2024-01-23
Anticipated expiration: 2042-06-24
Also published as: CN115157806A

Abstract

The invention provides a digital printing board and a preparation method thereof, when the thickness of a substrate layer is not less than 5mm, the digital printing board comprises a substrate layer mainly composed of hot-melt first resin and filler, a background film layer composited with the decorative surface of the substrate layer into a whole, a 2D pattern layer arranged on the surface of the background film layer and a 3D simulation layer mainly composed of second resin for covering the 2D pattern layer; when the thickness of the substrate layer is not more than 5mm, the digital printing plate comprises an elastic stress layer which is compounded with the base surface of the substrate layer into a whole in addition to the structure; the elastic stress layer and the background film layer are compounded with the substrate layer into a whole in an online pressing or coextrusion mode. According to the invention, through researching the thickness of the substrate layer and the quality of the product, two digital printing plates with different structures are provided based on the substrate layers with different thicknesses, so that the production process and the product structure can be simplified, and the product qualification rate can be ensured.

Description

Digital printing plate and preparation method thereof

Technical Field

The invention relates to the technical field of 3D printing plates, in particular to a digital printing plate and a preparation method thereof.

Background

Floors are often used in floor finishing. In order to improve the appearance grade of ground decoration, the solid wood floor is usually the first choice of high-grade decoration, and the formed wood grains and patterns can improve the visual aesthetic feeling. However, the solid wood floor has higher requirement on wood quality, high price, higher maintenance cost, larger economic expense caused by paving and using, and does not accord with the current environmental protection concept.

In order to reduce production and maintenance costs and increase the useful life of floors, many materials have been used to replace solid wood and some means have been used to make these alternative products also have wood grain and patterns. For example, patent application number CN202011282338.2 provides a stone-plastic floor, which uses PVC and stone powder as raw materials to prepare a stone-plastic substrate, and then a color film and other film layers are attached to the substrate. Compared with solid wood, the stone plastic base material has the advantages of water resistance, fire resistance, corrosion resistance and the like, the production cost and the maintenance cost are lower than those of the solid wood, and the attached color film can simulate the wood grain effect, so that the wood floor can be replaced to a certain extent. However, in reality, the wood grain is formed by a 3D structure, and the 2D wood grain formed by the color film has a larger visual difference from the real wood grain, so that a simulated solid wood floor with a lifelike appearance is difficult to obtain.

The indoor floor based on the polyolefin biomass composite material disclosed in the patent application No. CN202010237877.8 takes polyolefin and biomass materials as raw materials to prepare a core material, and then the outer layer of the core material is attached with a veneer, compared with a color film, the wood veneer has wood grains and has a certain thickness, so that the whole product has extremely strong wood texture, however, the rare veneer materials on the market are often in short supply at present, and therefore, certain limitation still exists in production.

Patent document CN202010725836.3 discloses an SPC-based 3D printing sheet, specifically, the sheet comprises an SPC substrate layer, a 3D printing color layer, and a UV protective layer; the substrate layer comprises an SPC core layer and a background film layer which is composited with the SPC core layer through coextrusion; the background film layer is also embossed with textures in the form of wood grains, patterns or designs; or the SPC substrate layer comprises an SPC core layer and a background film layer which is compounded with the SPC core layer through online lamination, and also comprises a resin concave-convex effect layer, wherein the resin concave-convex effect layer is arranged between the color layer and the UV protective layer. The patent document forms planar patterns by printing color layers, forms three-dimensional gully effects by embossing textures in wood grains, patterns or arranging resin concave-convex effect layers, further improves the wood-like effect of the plate, and does not need natural materials such as wood veneers and the like. However, this solution has a certain disadvantage in the implementation process, that is, the resin concave-convex effect layer needs to be formed on the substrate layer by using materials such as photo-polymerization resin, and in the photo-polymerization process, the surface layer stress is inevitably changed, and the cracking and bending phenomena of the whole plate often occur.

In the technical scheme of the patent application number CN202111419020.9, firstly, a base material for digital printing with an elastic stress layer on the base surface is prepared, then 3D printing operation is carried out on the decorative surface of the base material, the elastic stress layer is utilized to counteract the warping stress generated in the forming process of the pattern simulation layer, and the plate can be prevented from bending after the elastic stress layer and the pattern simulation layer are balanced. The purpose of this patent is to further solve the problem of cracking and bending of the substrate layer, which requires stress cancellation by the elastic stress layer and the pattern simulation layer. In the actual production process, in order to achieve the above effect, the material formulation and thickness of the elastic stress layer and the forming process of the elastic stress layer on the substrate need to be controlled specifically, and the elastic stress layer is prefabricated, so that the elastic stress layer has high requirements in manufacturing, the process needs to be controlled strictly, the effect is not obvious if the stress is small, and reverse warping easily occurs if the stress is large; at present, the product of the scheme is successful in pilot plant test, but large-scale production cannot be carried out, because the parameters are required to be strictly controlled, the equipment requirement is high, and the operation window is small.

Disclosure of Invention

The invention provides a digital printing plate and a preparation method thereof, which are used for solving the problems of cracking and bending possibly occurring in the whole plate and enabling the plate to be easier to implement production.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

a digital printing plate comprises a substrate layer mainly composed of a first hot-melt resin and a filler, a background film layer compounded with the decorative surface of the substrate layer into a whole, a 2D pattern layer arranged on the surface of the background film layer and a 3D simulation layer mainly composed of a second resin and covering the 2D pattern layer; the 3D simulation layer is formed with a concave-convex three-dimensional pattern structure; the thickness of the substrate layer is not less than 5mm.

The existing 3D grain forming mode is as follows: a pattern layer with a 2D pattern is formed on a substrate by printing and the like, then a layer of dynamic resin precursor (such as liquid composed of monomers of photopolymerized resin and an initiator thereof) is covered on the 2D pattern, then the dynamic resin precursor is subjected to local treatment, and finally the resin precursor is subjected to solidification treatment, so that the local treated part is not solidified or polymer with lower hardness is formed, and is easy to remove, and a 3D gully structure is formed after the removal. Generally, the 3D resin layer formed by curing the resin precursor is transparent, so that the pattern of the pattern layer can be observed through the 3D resin layer, and the gully structure formed by the resin layer can provide 3D visual effect for the 2D pattern, thereby forming the 3D grain of the wood imitation. The resin precursor is obviously shrunk in the curing process, so that the 3D resin layer generates stress from an edge part to a middle part, the stress pulls the substrate layer compounded with the 3D resin layer, the substrate layer warps towards the decorative surface side, the substrate layer is mainly made of PVC and more than 70% of inorganic mineral powder, the toughness is low, a fracture phenomenon is easily generated under the action of surface stress, more plasticizer is added into the substrate layer, so that the fracture phenomenon can be reduced to a certain extent, but too much plasticizer can lead to softer material of the substrate layer, and the warping degree generated when the substrate layer is stressed is larger, so that the product qualification rate is reduced. Therefore, the scheme of counteracting the stress of the 3D resin layer by adopting structures such as an elastic stress layer and the like in the prior art avoids bending and breaking of the plate. However, the inventors found that there was a significant yield difference for different batches of boards when producing 3D printed boards with the structure "elastic stress layer-substrate layer-background layer-3D resin layer". Therefore, the inventors have desired to solve the problem of large lot-to-lot variation. Through strict production management, the inventors have found that batch-to-batch problems are not mishandled. The inventor has to estimate that this is caused by the high parameter control requirement of the technical scheme of "elastic stress layer-substrate layer-background layer-3D resin layer" itself and the great implementation difficulty.

During product pilot runs, the inventors found that the thickness parameters of the substrate layer had some effect on the lot-to-lot variation. Accordingly, the inventors appropriately adjusted the thickness of the substrate. In the test, the inventors controlled the substrate thickness to be 4mm or more, and then conducted the technical scheme of "elastic stress layer-substrate layer-background layer-3D resin layer", found that the lot-to-lot variation was significantly reduced and the yield was improved. Therefore, the inventors have estimated that when the substrate layer reaches a certain thickness, the substrate has a strong resistance to the elastic stress of the surface layer. The inventors further associate that the provision of an elastic stress layer is not necessary if the substrate layer is further thickened.

The inventor carries out a series of experiments, and discovers that when the material of the base material is PVC as matrix resin and calcium carbonate as filler, and the content of the matrix resin and the plasticizer is not more than 25%, the thickness of the base material layer can be adjusted to 5mm, and the technical scheme of the whole plate warping and cracking problem does not occur. In the above experiments, the inventors conducted a series of formulation adjustments, and conducted studies on PVC resin, calcium carbonate filler, and plasticizer in different proportions, and found that 5mm was a threshold, i.e., it was difficult to adjust the thickness of the substrate to 5mm or less without using an elastic stress layer, without warping or cracking of the whole sheet.

That is, when the thickness of the substrate layer is above 5mm, the structural strength of the substrate layer is enough to resist the stress in the 3D resin layer forming process, so that the product can be ensured not to warp or break without adopting an elastic stress layer for the product, and the production procedure of the product can be reduced relative to the scheme of arranging the elastic stress layer.

In the prior art, the technical scheme for shielding the color of the substrate layer is to treat the substrate layer by adopting photo-curing white paint, namely, coating white paint on the decorative surface of the substrate layer, then treating the substrate layer by ultraviolet light, and forming a hard background layer formed by the white paint after the ultraviolet light treatment. The hard background layer formed by the white paint is mainly made of non-hot-melt high polymer materials, so that toughness is also lacking, the hard background layer is similar to the 3D resin layer, and the substrate layer is subjected to warping force towards one side of the decorative surface due to obvious volume shrinkage in the forming process, and the warping force of the substrate layer caused by the hard background layer and the 3D resin layer is superposed, so that the threshold value of stress damage of the plate is further reduced.

The "elastic stress layer" provided in the prior art can solve the above problems to some extent, but the scheme of the present invention adopts another scheme to improve the situation because the "elastic stress layer" is not provided, namely, a background film layer formed by hot-melt second resin is compounded on the decorative surface of the substrate layer to replace the photo-curing white paint, so as to solve the above-mentioned superposition problem. The background film layer can be extruded from the die together with the substrate layer by means of coextrusion; the method can also be adopted for on-line pressing and pasting, and the substrate layer is compounded into a whole by hot pressing when the substrate layer is extruded and is not completely cooled. Preferably, the method of pressing and pasting the prefabricated background film layer on line can be adopted, because the thickness of the prefabricated background film layer is easier to control, the color is more uniform after the prefabricated background film layer is compounded with the substrate layer, the thickness control is realized when the color of the substrate layer can be shielded by the background film layer, and the product quality is accurately controlled.

In addition, the background film layer is mainly formed by hot-melt resin materials, so that certain toughness can be provided for the substrate layer, a buffer effect can be achieved when one side of the decorative surface is impacted, and the effect cannot be achieved by a hard background layer formed by white paint.

Further, the transverse tensile strength of the background film layer is not lower than 25MPa, and the longitudinal tensile strength is not lower than 30MPa.

Further, the change rate of the transverse heating dimension of the background film layer is not more than 2%, and the change rate of the longitudinal heating dimension is not more than 6%.

Further, the thickness of the background film layer is no more than one fifth of the substrate layer.

For the background film layer produced by the extrusion molding method, there is generally some difference in the longitudinal tensile strength and the transverse tensile strength, and similarly, there is also some difference in the longitudinal and transverse dimensional change rates for the extrusion molded background film layer.

It should be noted that the heating dimensional change rate of the invention is based on the ISO23999-2021 standard, and the specific method is as follows: cutting a background film layer into 240 mm-240 mm samples, drawing two pairs of parallel lines with the interval of 200mm at the position 20mm away from the edge of the transverse direction and the longitudinal direction of the samples respectively to form four intersecting points, placing the samples above an aluminum plate, placing the samples for 24 hours under the conditions of 23+/-2 ℃ and 50+/-5% RH, measuring two initial intervals of the four intersecting points in the transverse direction and two initial intervals of the four intersecting points in the longitudinal direction respectively through calipers, and averaging to obtain a transverse initial interval A1 and a longitudinal initial interval B1; the temperature in the constant temperature drying oven is regulated to 80 ℃, the sample and the aluminum plate are put into the constant temperature drying oven together for 6 hours, then the sample and the aluminum plate are taken out, the sample and the aluminum plate are placed under the conditions of 23+/-2 ℃ and 50+/-5% RH for 24 hours, the two intervals of four intersection points in the transverse direction and the two intervals of four intersection points in the longitudinal direction are measured again through calipers, the transverse interval A2 and the longitudinal interval B2 are obtained by averaging, and the transverse heating dimensional change rate= (A2-A1)/A1 and the longitudinal heating dimensional change rate (B2-B1)/B1 are obtained.

Further, the background film layer has a thermal conductivity greater than the substrate layer.

Because the scheme of the invention does not contain an elastic stress layer, the back surface of the substrate layer lacks reverse balance force, so that the product quality problem in the composite forming process of the substrate and the background film layer needs to be considered, otherwise, when the stress generated by the background film layer is large enough, the risk of cracking the substrate layer still exists. In general, two thermoplastic materials are compounded into two paths, one is to perform the two-layer structure respectively, and then compound the two-layer structure into a whole by means of hot pressing, and the other is to co-extrude raw materials of the two-layer structure into the same mold to compound the two-layer structure into a whole, and because of differences of physical parameters of various aspects of the two-layer structure, certain aspects need to be considered in the forming process. For the hot pressing method, the two-layer structure needs to be heated and then cooled in the compounding process, and then a process from thermal expansion to cooling recovery exists in the process, so that different volume changes can occur in the two-layer structure respectively. For the substrate layer, the thermal expansion coefficient is small because the substrate layer contains a large amount of filler, and if the thermal expansion coefficient of the background film layer is large, the background film layer can shrink more and form stress in the process of cooling and recovering compared with the substrate layer, so that the structural stability of the substrate layer is affected. For the coextrusion method, a process of cooling the two-layer structure from a molten state to a solid state exists, and the process generally has the parameter of forming shrinkage, namely that the volume of the thermoplastic material after cooling and forming has certain shrinkage relative to the volume of the molten state in a mold, and when the forming shrinkage of the substrate layer and the background film layer has a large difference, large stress can be generated, but in the actual production process, the forming shrinkage of materials such as PVC, EVA and the like which are generally adopted by the film is less than 1%, so that the film cannot be obviously influenced. That is, in the case of the present invention, when the base material layer and the background film layer are laminated by the coextrusion method or the hot pressing method, it is generally necessary to consider the dimensional change rate of the film. In addition, the thinner the background film layer is, the better the background film layer is, but the thinner the background film layer may have some problems in performing the subsequent 2D pattern layer and 3D resin layer forming process, so the background film layer needs to be kept with a certain thickness to ensure enough structural strength, preferably a thickness of one fifth to one tenth of the substrate layer.

It is also considered that, for an individual substrate layer, both sides of the substrate layer are in direct contact with air during cooling, so the cooling rate is basically equivalent, but after a single-sided composite background film layer, the side cannot directly exchange heat with air for the substrate layer, and there is a problem that the cooling rate is reduced, so the heat conductivity of the background film layer needs to be improved, so that the heat conductivity of the background film layer is greater than that of the substrate layer, and the defect is overcome. Because the thermal conductivity coefficients of different resin materials are different, in order to ensure the relationship between the thermal conductivity coefficients of the background film layer and the substrate layer more conveniently and simply, the invention preferably can ensure that the base resins contained in the background film layer and the substrate layer are of the same type, for example, the base resins in the background film layer and the substrate layer are all PVC, and meanwhile, the substrate layer contains a filler with the thermal conductivity coefficient lower than that of the base resin, for example, heavy calcium and the like, so that the state that the thermal conductivity coefficient of the background film layer is larger than that of the substrate layer can be formed more easily.

Further, the first resin is polyolefin resin or polyvinyl chloride resin.

Further, the background film layer is light in color and can shade the color of the substrate layer. In the invention, the background film layer needs to cover the color of the substrate layer to avoid the influence of the color, the texture and the like formed by the substrate layer on the visual effects of the 2D pattern layer and the 3D resin layer, and meanwhile, the color of the background film layer cannot influence the visual effects of the 2D pattern layer and the 3D resin layer, so that the background film layer needs to be made of a non-transparent or semitransparent light-colored material, and preferably, the background film layer is an opaque white film layer.

Further, the surface of the 3D resin layer is also compounded with a surface protection layer. The surface protective layer is generally formed of a wear-resistant material, such as a photo-curable paint or the like, for protecting the concave-convex structure of the 3D resin layer from wear.

The invention also aims to provide another digital printing plate.

The digital printing plate comprises a substrate layer mainly composed of first resin and filler, a first background film layer compounded with the decorative surface of the substrate layer into a whole, an elastic stress layer compounded with the basal surface of the substrate layer into a whole, a 2D pattern layer arranged on the surface of the first background film layer, and a 3D simulation layer mainly composed of second resin for covering the 2D pattern layer; the 3D simulation layer is formed with a concave-convex three-dimensional pattern structure; the thickness of the substrate layer is not more than 5mm.

Further, the elastic stress layer is the same as the first background film layer, and the thickness of the elastic stress layer is not more than one fifth of the thickness of the substrate layer.

In practical production, the inventors found that when the thickness of the SPC substrate layer is less than 5mm, the produced plate with the structure of substrate layer-background layer-3D resin layer has certain defects in terms of yield, and the substrate layer is easy to crack. The method for solving the problem in the prior art is to arrange an elastic stress layer, namely the product structure is an elastic stress layer-substrate layer-background layer-3D resin layer, and the stress generated by the background layer and the 3D resin layer is counteracted by utilizing the elastic stress layer. However, in practical operation, since the elastic stress layer corresponds to a "background layer+3d resin layer", and the background layer is formed by compounding a plurality of photo-cured paint layers, it is theoretically necessary to consider shrinkage rates of various materials, and thus it is difficult to control the required thickness of the elastic stress layer in practical production. The inventors have analyzed that the main cause of cracking of the substrate layer is insufficient toughness of the substrate layer, because the SPC substrate layer contains a large amount of mineral powder filler and thus becomes hard but brittle, in the existing 3D printing technology, priming paint, white paint and 3D resin layer materials are required to coat the substrate layer, which all generate significant shrinkage during molding, thus generating stress, and brittle SPC substrate layer is difficult to withstand at a thickness of 4mm or less. Therefore, in order to solve the problem of cracking of the substrate layer, improvement is needed from two aspects, namely, the toughness of the substrate layer is enhanced, the stress resistance is improved, and the stress generated in the 3D printing process is reduced, so that the stress of the substrate layer is reduced. Based on the analysis, the invention provides a digital printing plate, wherein the two sides of the substrate layer of the plate are provided with the background film layer and the elastic stress layer in a coextrusion or online pressing mode, and the materials and the thicknesses of the preferable background film layer and the elastic stress layer are the same, namely, before 3D printing, the substrate layer forms a composite substrate of 'background film layer-substrate layer-background film layer', and as the two sides of the substrate layer are provided with elastic film layer structures, the overall toughness of the composite substrate is obviously enhanced compared with that of the substrate layer, the stress resistance threshold is improved, and meanwhile, the background film layer replaces priming paint and white paint in the prior art, so that the accumulation of stress is reduced, only the 3D resin layer generates stress in the 3D printing process, and the cracking probability of the substrate layer is further reduced. On the other hand, the thickness of the substrate layer is lower, so that the substrate layer is obviously influenced by the background film layer, and when the two surfaces of the substrate layer are both coated with the composite film layer, stress offset is formed between the two background film layers, so that the composite substrate structure is more stable.

On the other hand, in the invention, the elastic stress layer and the background film layer can be arranged simultaneously or sequentially, because even if the elastic stress layer and the background film layer are subjected to asymmetric stress due to the fact that the elastic stress layer and the background film layer are compounded sequentially, the stress of the composite substrate can be released in a hot rolling mode, and the composite substrate subjected to hot rolling treatment is basically symmetric in stress generated in the cooling process because the elastic stress layers on the two sides are the same as the material and the thickness of the background film layer, so that warping is not easy to occur.

The invention further provides a preparation method of the digital printing plate.

A preparation method of a digital printing plate comprises the following steps:

s1, mixing and heating a hot-melt first resin and a filler to form a first melt, and introducing the first melt into a mold to form a substrate layer precursor;

s2, conveying the prefabricated film to one side surface of the substrate layer precursor or conveying two layers of prefabricated films to two side surfaces of the substrate layer precursor respectively, carrying out online hot pressing on the film and the substrate layer precursor when the substrate layer precursor is not completely cooled and solidified, and then carrying out shaping treatment to obtain a composite substrate comprising the film and the substrate layer; or heating the raw materials for forming the background film layer or the raw materials for forming the background film layer and the elastic stress layer to form a second melt, introducing the second melt into a mold, coating the second melt on one side surface or two side surfaces of a substrate layer precursor which is not completely cooled, and compounding and shaping in the mold to obtain a composite substrate containing the background film layer and the substrate layer or a composite substrate containing the background film layer, the elastic stress layer and the substrate layer;

S3, forming a 2D pattern layer on a background film layer of the composite substrate through first printing equipment to obtain a first printing plate;

s4, uniformly applying a non-solid second resin composition to the surface of the 2D pattern layer of the first printing plate; the non-solid second resin composition is a mixed liquid containing a prepolymer, a monomer and an initiator which can be crosslinked to form a second resin; or the non-solid second resin composition is a molten second resin;

s5, applying a surface treatment liquid containing a polymerization inhibitor or a coagulant to the surface of the second resin composition according to a pattern shape through a second printing device, then curing the second resin composition in a cross-linking polymerization mode to form a 3D simulation layer precursor, and removing the surface treatment liquid or a mixture formed by the second resin composition and the surface treatment liquid to form a 3D simulation layer with a concave-convex three-dimensional pattern structure; the coagulant inhibitor is a mixed liquid containing a prepolymer and a monomer which can be crosslinked to form a third resin, and the tg value of the third resin is lower than that of the second resin;

and S6, coating a protective coating on the surface of the 3D simulation layer, and curing to form a surface protective layer to obtain the digital printing plate.

It should be noted that in the method provided by the invention, the substrate layer precursor may be compounded with a background film layer, or may be compounded with a background film layer and an elastic stress layer, and the specific process depends on the thickness of the substrate layer; if the thickness of the substrate layer is more than 5mm, only one background film layer is compounded, and one side surface compounded with the background film layer is called a decorative surface; if the thickness of the substrate layer is below 5mm, the background film layer and the elastic stress layer are compounded, when the background film layer and the elastic stress layer are compounded, the material and the thickness of the elastic stress layer and the background film layer are preferably the same, the optional side is printed when the 3D printing is carried out subsequently, the layer structure of the side, which is subjected to the 3D printing, and the substrate layer is called the background film layer, and the layer structure of the side, which is not subjected to the 3D printing, and the substrate layer is called the elastic stress layer, so the naming of the background film layer and the elastic stress layer depends on the implementation mode of the subsequent 3D printing process.

In the invention, the second resin is a photopolymerization resin, the second resin composition is a prepolymer, a monomer and an initiator for forming the photopolymerization resin, and when polymerization does not occur, the second resin composition is in a liquid paint state, so that the second resin composition can be uniformly coated on the surface of the background film layer formed with the 3D pattern. The surface treatment liquid may be a liquid substance containing a polymerization inhibitor, and when the surface treatment liquid is applied to the second resin composition, a mixture containing the polymerization inhibitor, a prepolymer, a monomer and an initiator is formed at a contact portion of the surface treatment liquid and the second resin composition, and when the second resin composition is subjected to photopolymerization treatment, the second resin composition which is not contacted with the surface treatment liquid is normally cured to form a hard photopolymerization resin, and the mixture is not cured or cured to form an low-hardness oligomerization resin due to the presence of the polymerization inhibitor, and is removed by means of flushing or the like in the subsequent treatment; or the surface treatment liquid is a mixed liquid containing a prepolymer and a monomer capable of being crosslinked to form a third resin with a lower tg value, the second resin composition and the surface treatment liquid are respectively cured when photo-curing is carried out, the second resin composition forms a harder second resin with a higher tg value, the surface treatment liquid forms a softer third resin with a lower tg value, the third resin can be removed from the surface of the second resin through a tool such as a steel brush in subsequent treatment, and after the third resin is removed, the surface of the second resin forms a gully structure formed by a space originally occupied by the third resin. The second resin composition may be preferably subjected to an ultraviolet pretreatment prior to the application of the surface treatment liquid, so that the fluidity of the second resin composition is reduced, so that the 3D simulation layer is shaped and a boundary is easily formed between the second resin composition and the surface treatment liquid, and the ultraviolet intensity and the treatment time should be controlled during the ultraviolet pretreatment to avoid the excessive curing degree of the second resin composition.

In summary, the following beneficial effects can be obtained by applying the technical scheme of the invention:

the invention can simplify the production process and the product structure and simultaneously ensure the product qualification rate by adjusting the thickness of the substrate layer. When the substrate layer is more than 5mm, the plate structure is a substrate layer-a background film layer-a 2D pattern layer-a 3D simulation layer, the stress generated by the 3D simulation layer is not required to be counteracted by attaching an elastic stress layer on the back surface of the substrate layer, the aim of preventing the substrate layer from cracking can be achieved by matching the structural strength of the substrate layer with the elastic background film layer made of a resin material, and the stress generated by the molding shrinkage of the white primer in the existing scheme of covering the color of the substrate layer by the white primer is also eliminated by arranging the background film layer; when the substrate layer is below 5mm, the plate structure is an elastic stress layer-substrate layer-background film layer-2D pattern layer-3D simulation layer, wherein the elastic stress layer, the background film layer and the substrate layer are pre-compounded and formed, then the 2D pattern layer and the 3D simulation layer are processed, the toughening effect of the elastic stress layer and the background film layer is utilized to avoid the problems of cracking and the like of the substrate layer in the subsequent 3D printing process, and the elastic stress layer and the background film layer are preferably made to be the same in material and thickness, so that the stress on two sides of the substrate layer is symmetrical, the probability of warping and cracking of the substrate layer is reduced, and meanwhile, when the material and the thickness of the substrate layer and the background film layer are the same, any surface of the composite substrate can be selected for 3D printing processing, so that the production and the processing are more convenient.

Detailed Description

Comparative example 1

S1, mixing PVC resin, heavy calcium carbonate, plasticizer and other additives, heating by a first extruder, and introducing into a die to form a substrate layer precursor; the substrate layer comprises 15 parts of PVC resin, 75 parts of heavy calcium carbonate, 3 parts of plasticizer, 3 parts of compatilizer, 1.5 parts of stabilizer, 1 part of lubricant and 0.5 part of antioxidant;

s2, mixing PVC resin and other additives, heating and melting the mixture through a second extruder, introducing the mixture into a secondary runner of a die to form an elastic stress layer precursor, coating a basal surface of the basal surface precursor, shaping and cooling a composite structure formed by the basal surface precursor and the elastic stress layer precursor, and guiding the composite structure out of the die to obtain a basal surface substrate with the elastic stress layer; wherein the thickness of the base material layer is 3mm, and the thickness of the elastic stress layer is 0.5mm;

s3, coating an adhesion primer on the decorative surface of the substrate by using a roller coater, wherein the coating weight is 10g/m ² Curing by ultraviolet light; in this example 395 nm, 8W/cm are used ² Is irradiated by an ultraviolet lamp;

s4, coating a white primer with a roller coater at 30g/m on the surface to which the primer is attached ² Curing by ultraviolet light; setting illumination intensity as in the previous step;

s5, the base material is LED into 2D printing equipment, patterns to be printed are LED into the 2D printing equipment, the size of the plate is set, the height of the printing head is set, and the vacuum adsorption device, the LED and the ultraviolet curing lamp are turned on; printing a required 2D plane pattern on the decorative surface of the substrate obtained in the last step; the color paste for printing the pattern is ultraviolet light curing color paste; after printing, shaping the pattern by irradiation of an ultraviolet curing lamp to obtain a first printing substrate; the equipment in the step is 2D printing equipment purchased in the market;

S6, coating a wear-resistant layer on the 2D plane pattern of the first printing substrate by using a roller coater, wherein the wear-resistant coating weight is 50g/m ² Ultraviolet curing; the illumination intensity operation is set as above;

s7, coating a second resin composition on the surface of the wear-resistant layer by a roller coater, wherein the second resin composition mainly comprises acrylic acidMethacrylic acid and oligomers thereof, wherein the acrylic acid, methacrylic acid monomers comprise about 70vol%; allowing a small amount of other monomers or their oligomers, such as methyl methacrylate, ethyl acrylate, etc., to be mixed; necessarily contains a small amount of photoinitiator; the coating amount of the second resin composition was 180g/m ² The method comprises the steps of carrying out a first treatment on the surface of the Carrying out photo-curing treatment by using ultraviolet curing equipment, so that the first resin layer on the surface of the product is incompletely cured when the product passes through the equipment;

s8, selectively spraying surface treatment liquid on the pattern simulation layer precursor at fixed points according to the printing pattern by using 3D printing equipment, and then respectively curing the second resin composition and the surface treatment liquid through ultraviolet light treatment; in this step, the surface treatment liquid is a photocurable monomer, but is different from the monomer in the third resin composition; in this example, the 3D ink is composed mainly of n-butyl methacrylate, n-hexyl methacrylate, and oligomers thereof; substances which allow small amounts of other monomers or their oligomers, such as methyl acrylate, ethyl acrylate and butyl acrylate, to be mixed in; necessarily contains a small amount of photoinitiator; wherein n-butyl methacrylate and n-hexyl methacrylate monomers comprise about 85% by volume;

S9, removing substances formed by solidification of the surface treatment liquid by using a roller brushing machine; in the process, the hardness of the steel brush of the brush roller is required to be regulated, and substances formed by solidification of the surface treatment liquid are removed and cleaned without generating scratches; generating a three-dimensional structure in the printed area by using the surface treatment liquid to form a surface texture with a 3D effect, and obtaining a formed 3D simulation layer;

s10, coating 10g/m on the surface of the 3D simulation layer ² And carrying out photo-curing treatment to form a surface protection layer, thus obtaining the digital printing plate.

Comparative example 2

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 3.5mm.

Comparative example 3

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 4mm.

Comparative example 4

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 5mm.

Comparative example 5

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 5.5mm.

Comparative example 6

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 6mm.

Comparative example 7

Substantially the same as in comparative example 1, except that the thickness of the base material layer was 7mm.

And (3) product testing: 50 square plates with the length and width specifications of 500mm multiplied by 500mm are respectively produced in batches according to the methods in the comparative examples 1-7, whether cracking and delamination phenomena occur on the plates are observed, the initial warping degree and the heating warping degree of the plates are measured, and the product qualification rate is counted, wherein the results are shown in the table 1. Wherein, the plate with the quality problem which can be observed by naked eyes and the plate with the heating warpage of more than 1mm/m are all marked as unqualified.

And (3) warpage detection flow: cutting a plate into 240 mm/240 mm samples, placing a wear-resistant layer upwards above an aluminum plate, placing for 24 hours at 23+/-2 ℃ and 50+/-5% RH, and measuring the initial warping degree of the plate by a caliper; the temperature in the constant temperature drying oven was adjusted to 80 ℃, the sample and the aluminum plate were put into the constant temperature drying oven and placed for 6 hours, then the sample and the aluminum plate were taken out, and placed under the conditions of 23.+ -. 2 ℃ and 50.+ -. 5% RH for 24 hours, and the heating warpage of the plate was measured by calipers.

Comparative examples 1 to 7 were adopted as a method for producing a 3D printing plate by setting an elastic stress layer to form a reverse warping force in the prior art, and as can be seen from the results in table 1, when the thickness of the substrate layer is lower than 4mm, the product yield is reduced, and the initial warping degree is higher, because the structural strength of the substrate layer itself is difficult to resist the stress generated by the elastic stress layer and easily generates reverse warping in the process of compounding the elastic stress layer when the substrate layer is thinner, the thinner the substrate layer is, the larger the reverse warping degree is, and even the substrate layer is cracked, and when the thickness of the substrate layer is greater than 4mm, the product yield can reach 100%, and the warping degree is smaller. Accordingly, the inventors propose that when the thickness of the base material layer is sufficiently large, stress formed during 3D printing can be directly resisted without cracking and warping is acceptable even in the case where the base material layer is not provided with an elastic stress layer.

Example 1

A preparation method of a digital printing plate comprises the following steps:

s1, mixing PVC resin with heavy calcium carbonate and other additives, heating the mixture through a first extruder to form a hot melt, and introducing the hot melt into a die to form a substrate layer; the substrate layer comprises 15 parts of PVC resin, 75 parts of heavy calcium carbonate, 3 parts of plasticizer, 3 parts of compatilizer, 1.5 parts of stabilizer, 1 part of lubricant and 0.5 part of antioxidant;

s2, when the substrate layer is not completely cooled and solidified, preheating and respectively unreeling the prefabricated film to one side surface of the substrate layer precursor, and then performing online hot pressing to form a background film layer on one side surface of the substrate layer to obtain a double-layer composite substrate; the thickness of the substrate layer in the composite substrate is 3.0mm, and the thickness of the background film layer is 0.5mm; the background film layer and the elastic stress layer are formed by mixing and extruding 2.0 parts of CPE resin, 60 parts of polyvinyl chloride, 0.8 part of polyethylene wax and 4.0 parts of rigid filler, and calendaring; the longitudinal tensile strength of the background film layer is 42.79MPa, the transverse tensile strength is 32.37MPa, the longitudinal heating dimensional change rate is 4.81 percent, and the transverse heating dimensional change rate is 1.53 percent;

s3, introducing the composite substrate into 2D printing equipment, introducing patterns to be printed on the 2D printing equipment, setting the size of a plate, setting the height of a printing head, and turning on a vacuum adsorption device, an LED and an ultraviolet curing lamp; printing a required 2D plane pattern on any background film layer of the composite substrate obtained in the last step; the color paste for printing the pattern is ultraviolet light curing color paste; after printing, shaping the pattern by irradiation of an ultraviolet curing lamp to obtain a first printing substrate; the equipment in the step is 2D printing equipment purchased in the market;

S4, after the 2D plane pattern is solidified, coating a wear-resistant layer on the SPC substrate with the 2D plane pattern by using a roller coater, wherein the wear-resistant coating weight is 50g/m < 2 >, and ultraviolet light is solidified; the illumination intensity operation is set as above;

s5, coating a second resin composition on the surface of the wear-resistant layer through a roller coater to form a pattern simulation layer precursor, wherein the second resin composition is mainly an oligomer composed of methyl methacrylate and a monomer thereof, and the methyl methacrylate monomer accounts for about 70vol%; allowing small amounts of other monomers or their oligomers, such as acrylic acid, methacrylic acid and their oligomers; necessarily contains a small amount of photoinitiator; the coating amount of the second resin composition was 200g/m ² The method comprises the steps of carrying out a first treatment on the surface of the Carrying out photo-curing treatment by ultraviolet curing equipment to enable the first resin layer on the surface of the product to be incompletely cured when the product passes through the equipment;

s6, utilizing 3D printing equipment, selectively spraying surface treatment liquid on the pattern simulation layer precursor at fixed points according to a printing pattern, and then curing the second resin composition and the surface treatment liquid respectively through ultraviolet light curing; in the embodiment, the surface treatment liquid consists of a photosensitive polymerization inhibitor and a solvent thereof, and the components of the surface treatment liquid are 8 percent of tris (N-nitroso-N-phenylhydroxylamine) aluminum salt and 92 percent of 2-phenol ethoxyacrylate;

S7, removing substances formed by solidification of the surface treatment liquid by using a roller brushing machine; in the process, the hardness of the steel brush of the brush roller is required to be regulated, and substances formed by solidification of the surface treatment liquid are removed and cleaned without generating scratches; then spraying a cleaning liquid to remove residual liquid which remains on the surface and is not solidified due to the surface treatment liquid, and drying; generating a three-dimensional structure in the printed area by using the surface treatment liquid to form a surface texture with a 3D effect, and obtaining a formed 3D simulation layer;

s8, coating 10g/m on the surface of the 3D simulation layer ² And carrying out photo-curing treatment to form a surface protection layer, thus obtaining the digital printing plate.

Example 2

Substantially the same as in example 1, except that the thickness of the base material layer was 3.5mm.

Example 3

Substantially the same as in example 1, except that the thickness of the base material layer was 4mm.

Example 4

Substantially the same as in example 1, except that the thickness of the base material layer was 4.5mm.

Example 5

Substantially the same as in example 1, except that the thickness of the base material layer was 5mm.

Example 6

Substantially the same as in example 1, except that the thickness of the base material layer was 6mm.

The results of testing the product yields and average warpage of examples 1 to 6 are shown in table 2. The warpage test method is the same as in table 1.

Embodiment 1~6 is for the scheme that does not set up elastic stress layer, can see from table 2 that substrate layer thickness improves to 5 mm's in-process by 3mm gradually, and the qualification rate of product improves gradually, and the average warp degree of product reduces, when substrate layer thickness is not less than 5mm, the product qualification rate has reached 100%, consequently be not less than 5mm at substrate layer thickness, need not set up elastic stress layer and can realize the production of 3D printing panel, compare in prior art process simpler, and avoided the reverse warp and the fracture of substrate layer because of elastic stress layer's setting up leads to.

Example 7

A preparation method of a digital printing plate comprises the following steps:

s1, mixing PVC resin with heavy calcium carbonate and other additives, heating the mixture through a first extruder to form a hot melt, and introducing the hot melt into a die to form a substrate layer; the substrate layer comprises 20 parts of PVC resin, 70 parts of heavy calcium carbonate, 4 parts of plasticizer, 3 parts of compatilizer, 1.5 parts of stabilizer, 1 part of lubricant and 0.5 part of antioxidant;

s2, when the substrate layer is not completely cooled and solidified, preheating and respectively unreeling the prefabricated film to one side surface of the substrate layer precursor, and then performing online hot pressing to form a background film layer on one side surface of the substrate layer to obtain a double-layer composite substrate; the thickness of the substrate layer in the composite substrate is 3.0mm, and the thickness of the background film layer is 0.5mm; the background film layer and the elastic stress layer are formed by mixing, extruding and calendaring 2.0 parts of CPE resin, 1 part of EVA resin, 60 parts of polyvinyl chloride, 0.8 part of polyethylene wax and 3.0 parts of rigid filler; the longitudinal tensile strength of the background film layer is 43.42MPa, the transverse tensile strength is 32.56MPa, the longitudinal heating dimensional change rate is 4.85%, and the transverse heating dimensional change rate is 1.56%;

Example 8

Substantially the same as in example 7, except that the thickness of the base material layer was 4mm.

Example 9

Substantially the same as in example 7, except that the thickness of the base material layer was 5mm.

Example 10

Substantially the same as in example 7, except that the base material layer comprises 25 parts of PVC resin, 65 parts of heavy calcium carbonate, 5 parts of plasticizer, 3 parts of compatilizer, 1.5 parts of stabilizer, 1 part of lubricant and 0.5 part of antioxidant;

example 11

Substantially the same as in example 10, except that the thickness of the base material layer was 4mm.

Example 12

Substantially the same as in example 10, except that the thickness of the base material layer was 5mm.

The results of testing the product yields and average warpage of examples 7 to 12 are shown in table 3. The warpage test method is the same as in table 1.

Examples 7-9 and examples 10-12 respectively adopt different substrate layer schemes from comparative examples 1-6, the proportions of PVC resin, plasticizer and heavy calcium in the substrate layer are changed, and from the results of Table 3, the adjustment of the proportions of the three has no obvious influence on the overall qualification rate trend, and the qualification rate of the product can be ensured only when the thickness of the substrate reaches 5mm, so that the method without arranging an elastic stress layer can be adopted when the thickness of the substrate is more than 5mm.

Example 13

A preparation method of a digital printing plate comprises the following steps:

s2, when the substrate layer is not completely cooled and solidified, preheating two layers of prefabricated films with the same material and thickness, respectively unreeling the prefabricated films onto two side surfaces of a precursor of the substrate layer, and then performing online hot pressing to respectively form two sides of the substrate layer to obtain a three-layer composite substrate; the thickness of the substrate layer in the composite substrate is 3.0mm, and the thickness of the background film layer is 0.3mm; the background film layer is formed by mixing, extruding and calendaring 2.0 parts of CPE resin, 60 parts of polyvinyl chloride, 0.8 part of polyethylene wax and 4.0 parts of rigid filler; the longitudinal tensile strength of the background film layer is 42.79MPa, the transverse tensile strength is 32.37MPa, the longitudinal heating dimensional change rate is 4.81 percent, and the transverse heating dimensional change rate is 1.53 percent;

s5, coating a second resin composition on the surface of the wear-resistant layer through a roller coater to form a pattern simulation layer precursor, wherein the second resin composition is mainly an oligomer composed of methyl methacrylate and a monomer thereof, and the methyl methacrylate monomer accounts for about 70vol%; allowing small amounts of other monomers or their oligomers, such as acrylic acid, methacrylic acid and their oligomers; necessarily contains a small amount of photoinitiator; the coating amount of the second resin composition was 200g/m ² The method comprises the steps of carrying out a first treatment on the surface of the Performing light curing treatment by ultraviolet light curing equipment, wherein the illumination intensity or the passing time is properly adjusted downwards in the step, so that the first resin layer on the surface of the product is not completely cured when the product passes through the equipment; if the illumination intensity is adjusted to be 0.8 times of the original intensity or the passing time is set to be 0.8 times of the original intensity;

Example 14

S1, mixing PVC resin with heavy calcium carbonate and other additives, heating the mixture through a first extruder to form a hot melt, and introducing the hot melt into a die to form a substrate layer precursor; the substrate layer comprises 20 parts of PVC resin, 70 parts of heavy calcium carbonate, 4 parts of plasticizer, 3 parts of compatilizer, 1.5 parts of stabilizer, 1 part of lubricant and 0.5 part of antioxidant;

s2, when the substrate layer is not completely cooled and solidified, heating a background film layer raw material through a second extruder to form a second melt, introducing the second melt into a die to cover the decorative surface of the substrate layer precursor, heating an elastic stress layer raw material through a third extruder to form a third melt, introducing the third melt into the die to cover the basal surface of the substrate layer precursor, and cooling and shaping to obtain a three-layer composite substrate; the thickness of the substrate layer in the composite substrate is 3.0mm, and the thickness of the background film layer is 0.3mm; the background film layer and the elastic stress layer are both formed by mixing and extruding 2.0 parts of CPE resin, 60 parts of polyvinyl chloride, 0.8 part of polyethylene wax and 4.0 parts of rigid filler, and then calendaring; the longitudinal tensile strength of the background film layer is 42.79MPa, the transverse tensile strength is 32.37MPa, the longitudinal heating dimensional change rate is 4.81%, the transverse heating dimensional change rate is 1.53%, and the molding shrinkage rate is 0.62%;

s5, coating a second resin combination on the surface of the wear-resistant layer through a roller coaterA second resin composition which is an oligomer mainly composed of methyl methacrylate and a monomer thereof, wherein the methyl methacrylate monomer accounts for about 70% by volume in this example; allowing small amounts of other monomers or their oligomers, such as acrylic acid, methacrylic acid and their oligomers; necessarily contains a small amount of photoinitiator; the coating amount of the second resin composition was 200g/m ² The method comprises the steps of carrying out a first treatment on the surface of the Performing light curing treatment by ultraviolet light curing equipment, wherein the illumination intensity or the passing time is properly adjusted downwards in the step, so that the first resin layer on the surface of the product is not completely cured when the product passes through the equipment; if the illumination intensity is adjusted to be 0.8 times of the original intensity or the passing time is set to be 0.8 times of the original intensity;

Example 15

Substantially the same as in example 13, except that the thickness of the base material layer was 3.5mm.

Example 16

Substantially the same as in example 13, except that the thickness of the base material layer was 4mm.

Example 17

Substantially the same as in example 13, except that the thickness of the base material layer was 4.5mm.

The results of testing the product yields and average warpage of examples 13 to 17 are shown in table 4. The warpage test method is the same as in table 1.

As can be seen from table 4, by setting the background film layer and the elastic stress layer of the same material and thickness on the two side surfaces of the substrate layer, and then performing 3D printing on the composite substrate, the qualification rate of the substrate with the thickness below 5mm can reach the standard. In the scheme of the invention, as the stress on the two sides of the composite substrate is basically balanced, the problem of easy reverse warping in turn cannot occur as in the prior art, and meanwhile, the elastic stress layers and the background film layers on the two sides provide toughness for the substrate layer, so that the substrate layer is not easy to crack, and when the substrate layer is affected by stress in the 3D printing process, the elastic stress layer also forms internal tension to resist warping. Compared with the scheme of only setting a single-sided background film layer in embodiments 1-12, the heating warp degree is reduced to a certain extent by setting a double-sided background film layer, so that one background film layer serves as an elastic stress layer, and the heating warp degree of the product can be reduced to a certain extent because two background film layers can synchronously change in volume in the heating process.

In summary, according to the digital printing board and the production method thereof, which are obtained by the high qualification rate and the high qualification rate of the product with the structure of elastic stress layer-substrate layer-background layer-3D resin layer in the prior art, when the actual production exists, specifically, when the thickness of the substrate is more than 5mm, the basic structure of the digital printing board is the substrate layer-background film layer-3D resin layer, and when the thickness of the substrate is less than 5mm, the basic structure of the digital printing board is the elastic stress layer (background film layer) -substrate layer-background film layer-3D resin layer.

The above specific embodiments are provided for illustrative purposes only and not for limiting the invention, and modifications of no inventive contribution to the embodiments may be made by those skilled in the art after having read the present specification, as long as they are within the scope of the claims of the present invention.

Claims

1. A digital printing board, which is characterized in that: the decorative material comprises a substrate layer mainly composed of hot-melt first resin and filler, a background film layer composited with the decorative surface of the substrate layer into a whole, a 2D pattern layer arranged on the surface of the background film layer and a 3D simulation layer mainly composed of second resin for covering the 2D pattern layer; the base material layer takes PVC as matrix resin and calcium carbonate as filler, the content of the matrix resin and the plasticizer is not more than 25%, and the thickness of the base material layer is not less than 5mm; the 3D simulation layer is formed with a concave-convex three-dimensional pattern structure; the background film layer has a transverse tensile strength not lower than 25MPa, a longitudinal tensile strength not lower than 30MPa, a transverse heating dimensional change rate not higher than 2%, a longitudinal heating dimensional change rate not higher than 6%, a thickness not higher than one fifth of that of the substrate layer, and a heat conductivity coefficient larger than that of the substrate layer, and contains the same matrix resin as that of the substrate layer.

2. The method for preparing the digital printing plate as claimed in claim 1, comprising the following steps:

s2, conveying the prefabricated film to one side surface of the substrate layer precursor, carrying out online hot pressing on the film and the substrate layer precursor when the substrate layer precursor is not completely cooled and solidified, and then carrying out shaping treatment to obtain a composite substrate containing the film and the substrate layer; or heating the raw materials for forming the background film layer to form a second melt, introducing the second melt into a mold, coating the second melt on one side surface of a substrate layer precursor which is not completely cooled, and compounding and shaping in the mold to obtain a composite substrate comprising the background film layer and the substrate layer;