JP2015139984A - Production method of woody decorative plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a woody decorative plate where the peel strength of a clear layer to a projection plate can be sufficiently and stably enhanced when producing the woody decorative plate by forming lamination by the injection molding of a resin base material layer and the clear layer consisting of a transparent resin respectively on the rear surface and front surface of the projection plate.SOLUTION: An adhesion layer consisting of a thermoplastic acryl resin is formed by coating an acrylic syrup on an undercoat layer and polymerizing the coating after an acrylic urethane coating is coated on the front surface side of a projection plate and the undercoat layer in an incompletely cured state is formed. After that, the lamination of a base material layer is formed by injection molding on the rear surface side of the projection plate and the lamination of a clear layer is formed by the injection molding of an acryl resin or a polycarbonate resin on the adhesion layer at the front surface side of the projection plate.

Description

  The present invention relates to a method for producing a wooden decorative board, and in particular, is advantageous for a wooden decorative board in which a wooden veneer and a clear layer made of a transparent synthetic resin are laminated on a synthetic resin base material layer. It relates to a manufacturing method.

  Conventionally, as a type of decorative board used to improve the appearance and appearance of various articles, there is a decorative board that is decorated with woodgraining, for example, as a surface material for furniture and household appliances, etc. Alternatively, it has been used as an automobile interior part. Such a decorative board is generally required to have a surface that is difficult to be scratched, and in particular, a more realistic wood for those used as luxury furniture, luxury passenger car interior parts, etc. It is required to have a texture.

  As a decorative board that can satisfy these requirements, a thin wooden veneer is laminated on a base layer made of a hard synthetic resin, and a transparent clear layer as a protective layer is formed on the surface of the veneer. A wood decorative board formed by laminating is known. In this wood decorative board, the scratch resistance of the surface is enhanced by the clear layer, and a more realistic wood texture can be obtained by using a real wood veneer.

  However, in many of such conventional wooden decorative boards, the clear layer is formed by performing spray coating using a clear paint a plurality of times, and thus the clear layer forming process is complicated. It was to become. Moreover, since it is difficult to obtain a smooth surface with a coating layer formed by spray coating, a polishing step after the coating step is essential when forming a clear layer with a coating layer. It was. Therefore, in the conventional wooden decorative board in which a veneer with a clear coating film formed on the surface is laminated on the base material layer, the number of processes at the time of manufacturing is large, and therefore the manufacturing cost increases. Moreover, it has been unavoidable that the productivity is low.

  Under such circumstances, the applicant of the present application previously described in Japanese Patent Application No. 2011-249354 [Japanese Patent Laid-Open No. 2013-103421 (Patent Document 1)] in which the peel strength of the clear layer with respect to the veneer is sufficiently increased. Revealed the decorative board. There, a base layer made of synthetic resin is laminated on the back surface of a wooden veneer by injection molding, while a clear layer made of transparent synthetic resin is laminated on the surface of the veneer by injection molding. Thus, a wooden decorative board is manufactured. In such a wood decorative board manufacturing method, the clear layer is laminated on the surface of the veneer by performing only one injection molding process, and the cavity surface of the molding die is mirror-finished. The polishing step for the layer can be omitted. Therefore, in the manufacturing method of such a wooden decorative board, a significant reduction in man-hours and a sufficient reduction in cost are realized in comparison with the conventional manufacturing method in which a clear coating film is formed on the surface of the veneer. It can be done.

  Further, in the above-mentioned patent document, in order to increase the peel strength of the clear layer with respect to the veneer, a clear layer made of acrylic resin on the surface of the veneer is provided through a coating layer made of a two-component curable acrylic urethane paint. It has been demonstrated that the layers are stacked. That is, the isocyanate contained in the coating layer formed on the surface of the veneer is urethane-bonded with the hydroxyl groups in cellulose constituting the wood structure or fiber structure of the veneer, thereby forming the veneer and the coating layer. Since the acrylic resin is contained in the coating layer while being bonded firmly chemically, the acrylic resin in the coating layer and the acrylic resin constituting the clear layer are fused at the time of injection molding of the clear layer. The coating layer and the clear layer are firmly bonded by mixing at the molecular level of the same resin. As a result, the surface of the veneer and the clear layer can be bonded chemically and strongly via the coating layer.

  By the way, in the above-mentioned Patent Document 1, in order to firmly bond the coating layer made of the two-component curable acrylic urethane coating and the clear layer, the coating layer is completely cured during the injection molding of the clear layer. In other words, it is necessary to be in an incompletely cured state. However, since such a coating layer gradually cures after its formation, the time for which it is in an incompletely cured state is limited. Therefore, depending on the time taken from the formation of the coating layer to the injection molding of the clear layer, there arises a problem that the coating layer is completely cured by the injection molding of the clear layer. In addition, when the base material layer is formed prior to the formation of the clear layer after the formation of the paint film layer, the coating film is formed by the heat of the molten resin or mold when the base material layer is injection molded. The hardening of the layer is accelerated, and the coating layer may be completely cured. Thus, if the coating layer becomes completely cured during the injection molding of the clear layer, it becomes difficult to firmly bond the coating layer and the clear layer, and the peel strength of the clear layer is reduced. The problem of degrading or becoming unstable is brought about.

  Furthermore, at the time of injection molding of the clear layer, it is extremely difficult to grasp the cured state of the coating layer in the cavity of the injection mold. In particular, when a base material layer and a clear layer are continuously formed by injection using a technique such as two-color molding, the formation of the base material layer promotes the curing of the coating layer as described above. However, it is difficult to confirm the cured state. Thus, at the time of injection molding of the clear layer, it is difficult to accurately grasp the cured state of the coating layer, which is also a cause of unstable peeling strength of the clear layer.

JP 2013-103421 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is a clear substrate made of a resin base material layer and a transparent resin on the back side and the front side of the protruding plate. To provide a method for producing a wooden decorative board capable of sufficiently and stably increasing the peel strength of the clear layer with respect to the veneer in the production of the wooden decorative board in which the layers are laminated by injection molding. is there.

  In the present invention, in order to solve such a problem, a synthetic resin base material layer is formed by injection molding on the back side of a wooden veneer that gives a design surface, while the surface of the veneer On the side, a method for producing a wooden decorative board in which a clear layer made of a transparent synthetic resin is laminated by injection molding, wherein (a) an acrylic urethane paint is applied to the surface side of the protruding board A step of forming an incompletely cured undercoat layer, and (b) an acrylic syrup is further coated on the incompletely cured undercoat layer formed on the surface side of the veneer to polymerize. A step of forming an adhesive layer made of a thermoplastic acrylic resin, (c) a step of completely curing the undercoat layer simultaneously with or after the formation of the adhesive layer, and (d) Projections formed by these undercoat layers and adhesive layers In contrast, the step of laminating and forming the base material layer by injection molding on the back surface side, and (e) an acrylic resin on the adhesive layer on the surface side of the protruding plate on which the base material layer is laminated Alternatively, the gist of the present invention is a method for producing a wooden decorative board, comprising the step of fusing the clear layer with the adhesive layer to form a laminate by injection molding of polycarbonate resin.

  Incidentally, in the method for producing a wooden decorative board according to the present invention, the surface of the incompletely cured undercoat layer formed on the surface side of the veneer is polished and exposed to the surface exposed by the polishing operation. On the other hand, a method in which the acrylic syrup is applied is advantageously employed.

  Moreover, according to one of the desirable aspects of the manufacturing method of the wooden decorative board according to this invention, the coating-film layer which consists of a polyester-type urethane coating is formed with respect to the surface of the said veneer, On this coating-film layer The undercoat layer will be formed.

  Furthermore, in another desirable aspect of the present invention, a method of forming the clear layer with a polycarbonate resin and further forming a hard coat layer on the clear layer is employed.

  That is, in the manufacturing method of the wood decorative board according to the present invention, by applying acrylic syrup on the incompletely cured undercoat layer formed on the surface side of the veneer, and solidifying by polymerization, Since the adhesive layer is formed and the primer layer is completely cured simultaneously with or after the formation of the adhesive layer, the acrylic resin and acrylic syrup in the partially cured primer layer Since the acrylic resin in the formed adhesive layer is the same resin, the primer layer and the adhesive layer are chemically bonded firmly by mixing at the molecular level.

  In addition, since the base material layer is formed by injection molding on the back surface side of the veneer plate on which the undercoat layer and the adhesive layer have already been formed, the base layer is heated by the heat during the injection molding. The problem of hard bonding between the primer layer and the adhesive layer is advantageously eliminated because the curing of the coating layer is accelerated and the primer layer is completely cured before the adhesive layer is formed. Will be.

  Furthermore, the adhesive layer is made of thermoplastic acrylic resin formed from acrylic syrup, and a clear layer is laminated on the adhesive layer on the surface side of the veneer by injection molding of acrylic resin or polycarbonate resin. Therefore, at the time of injection molding of the clear layer, the thermoplastic acrylic resin constituting the adhesive layer and the acrylic resin or polycarbonate resin forming the clear layer are thermally fused, and the adhesive layer and the clear layer are separated. It can be bonded chemically and firmly.

  In the present invention, as described above, from the point where the clear layer is laminated on the surface side of the veneer, the surface of the veneer and the clear layer are connected via the lower coating film and the adhesive layer. Therefore, it is possible to bond chemically and firmly, and thus the peel strength of the clear layer can be more sufficiently and stably increased.

  The acrylic syrup coating operation according to the present invention does not need to be performed in a closed space such as in the cavity of an injection mold, so it can be performed while confirming the cured state of the undercoat layer. It becomes. Therefore, an adhesive layer can be formed more reliably by applying acrylic syrup on the incompletely cured undercoat layer and polymerizing it, so that the undercoat layer and the adhesive layer are stable. Thus, it is possible to effectively contribute to stable and strong bonding between the surface of the protruding plate and the clear layer.

It is sectional explanatory drawing which shows one Embodiment of the laminated structure of the wooden decorative board manufactured according to this invention method. It is a cross-sectional explanatory drawing which shows the veneer sheet | seat which comprises some wooden decorative boards shown by FIG. It is explanatory drawing which shows an example of the process implemented when manufacturing the wooden decorative board shown by FIG. 1, Comprising: (a) is coating acrylic urethane paint on the veneer sheet | seat shown by FIG. (B) shows a state in which the undercoating layer in an incompletely cured state is formed by proceeding the curing of the paint. It is explanatory drawing which shows the process implemented following the process shown by FIG. 3, Comprising: The state which applied the acrylic syrup on the undercoat layer of an incomplete hardening state is shown. It is longitudinal cross-sectional explanatory drawing which shows the main wood sheet which comprises some wooden decorative boards shown by FIG. FIG. 3B is an enlarged explanatory view of a part A in FIG. 3B, in which FIG. 3A is a state where the curing is relatively advanced at the surface portion of the undercoat layer, and FIG. 3B is a view where such a surface portion is removed by polishing. Shows the state. It is explanatory drawing which shows other embodiment of the wooden decorative board manufactured according to this invention method, Comprising: (a) is sectional explanatory drawing corresponding to FIG. 1, (b) is B section expanded description in (a). FIG. It is sectional explanatory drawing corresponding to FIG. 1 which shows another embodiment of the wooden decorative board manufactured according to this invention method.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, in FIG. 1, a part of a wooden decorative board 10 used as an interior part for an automobile, which is an example of a wooden decorative board manufactured according to the method of the present invention, is schematically shown in cross-sectional form. The wooden decorative board 10 has a veneer sheet 18 in which a reinforcing layer 14 and a bonding layer 16 are laminated and formed on the back surface (lower surface in FIG. 1) side of the veneer 12. The undercoat layer 22 and the adhesive layer 24 are laminated and formed on the surface side of the projecting plate 12 of the projecting plate 12 of the projecting plate sheet 18, thereby forming the main wood sheet 26. A clear layer 28 is provided on the surface of the main wood sheet 26 (the upper surface in FIG. 1 of the adhesive layer 24), and a base material is provided on the rear surface (the lower surface in FIG. 1 of the bonding layer 16). Each of the layers 30 is laminated by injection molding. In other words, here, the wood decorative board 10 is formed on the base material layer 30, the joining layer 16, the reinforcing layer 14, the projecting board 12, the undercoat layer 22, the adhesive layer 24, and the clear layer 28 in that order. The rectangular flat plate-like laminated structure is formed by lamination. In the following, for the sake of convenience, the upper surface in FIG. 1 of the wooden decorative board 10 that is the design surface 20 side of the protruding plate 12 is referred to as the front surface, and the opposite surface is referred to as the back surface. In FIG. 1 and FIGS. 2 to 8 to be described later, in order to facilitate understanding of the structure of the wood decorative board 10 of the present embodiment, the thickness of each layer including the protruding board 12 is set to the clear layer 28 or the base layer. It should be understood that the exaggerated size is different from the actual size compared to the thickness of the material layer 30.

  Further, in the wooden decorative board 10, a thin covering layer 31 that covers the entire outer peripheral portion (end portion) of the main wood sheet 26 is integrally formed as a part of the base material layer 30. Thereby, the edge part of the main tree sheet | seat 26 containing the protrusion 12 is protected by the coating layer 31, and the damage | wound of the edge part of this main tree sheet | seat 26 and contact with air are prevented. . Moreover, since the coating layer 31 is opaque, the end of the main wood sheet 26 is prevented from being visually recognized from the outside, and the design of the wooden decorative board 10 is improved.

  In the present invention, the wooden decorative board 10 having such a structure is manufactured according to the following procedure.

  That is, first, a veneer sheet 18 having a structure as shown in FIG. 2 is prepared. When preparing the projecting plate sheet 18, the flat projecting plate 12 is prepared by cutting out from a predetermined piece of wood. When this protruding plate 12 is cut out from predetermined wood, a desired grain is made to appear on the surface (design surface 20). And the well-known drying process is given to the protruding board 12 cut out from the predetermined | prescribed wood as needed.

  Such a veneer 12 is provided to give a realistic wood texture to the wood decorative board 10 and is preferably, for example, Obankor, Bubinga, Birdseye Maple, Curly Maple, White Ash, Sapperima Hogany, Tamo It is made of a flat plate material obtained by slicing various natural trees, such as cedar, cypress, cherry, teak, etc., so that the desired grain such as planks, birch, and birch appears.

  On the other hand, an aluminum thin plate having a rectangular flat plate shape substantially the same size as the protruding plate 12 constituting the reinforcing layer 14 is prepared by cutting out from a predetermined blank or the like by press molding or the like. The reinforcing layer 14 has a rigidity that can give a desired rigidity to the veneer sheet 18 or the main wood sheet 26, and is not damaged by pressure or heat during injection molding of the base material layer 30. If it is a thing, the material will not be limited at all, for example, other metal thin plates, such as iron and copper, hard resin sheets, such as polypropylene and ABS resin, or a nonwoven fabric, and also glass fiber and carbon Any fiber sheet such as fiber can be used instead of the aluminum thin plate.

  Further, separately from the projecting plate 12, a rectangular flat plate-shaped wood board that is substantially the same size as the projecting plate 12 and that constitutes the bonding layer 16 is prepared by cutting out from predetermined wood. Note that, when cutting a wooden board from a predetermined wood, the direction of the grain is not limited, but as such wood, there are those having coarser grain than the wood from which the protruding board 12 is cut, for example, Claro walnut, Manga shirono, etc. Can be selected. And the well-known drying process is given to the wooden board cut out from the predetermined | prescribed timber as needed.

  Next, after forming the adhesive layer 32 on the back surface of the protruding plate 12 using a known adhesive capable of firmly bonding wood and metal, the prepared aluminum thin plate is passed through the adhesive layer 32. Then, the reinforcing layer 14 is laminated and formed on the back surface of the protruding plate 12 by bonding to the back surface of the protruding plate 12. As a result, the rigidity of the veneer 12 is enhanced, and therefore the handling performance of the veneer sheet 18 or the main wood sheet 26 when the wood decorative board 10 is manufactured is advantageously improved.

  Thereafter, the adhesive layer 34 is formed on the back surface of the reinforcing layer 14 by using an adhesive similar to the adhesive constituting the adhesive layer 32, and then the previously prepared wooden board is passed through the adhesive layer 34. Then, it adheres to the back surface of the reinforcing layer 14. As a result, the bonding layer 16 is laminated on the back surface of the protruding plate 12 via the reinforcing layer 14, and thus the protruding plate sheet 18 is obtained.

  In the method of the present invention, a resin material that constitutes the base material layer 30 is not always selected to have excellent bondability or adhesion to a metal material. Therefore, here, the bonding layer 16 having excellent bonding property or adhesion to the base material layer 30 is laminated on the back surface of the reinforcing layer 14.

  Subsequently, as shown in FIG. 3A, an acrylic urethane paint is applied on the design surface 20 of the projecting plate 12 (projected plate sheet 18) in which the reinforcing layer 14 and the bonding layer 16 are laminated on the back surface. The undercoat layer 22 is formed by coating by a known method. As the acrylic urethane paint for forming such an undercoat layer 22, various known paints can be used. In this embodiment, a polyisocyanate compound as a curing agent and a main agent are used. A so-called two-component curable acrylic urethane paint in which the acrylic polyol is blended at a certain ratio in use is used. Moreover, the coating method of such an acrylic urethane paint is not limited at all. That is, the undercoat layer 22 is a variety of known coating methods in which an acrylic urethane paint is applied to the design surface 20 of the projecting plate 12 using, for example, a roller or a brush, or is spray-coated. Any one of these is appropriately adopted and formed.

  Here, when the undercoat layer 22 is directly laminated on the design surface 20 of the projecting plate 12 as in the present embodiment, the concave and convex portions and the holes existing in the design surface 20 are filled, and further, In order to ensure the smoothness of the surface of the undercoat layer 22 (upper surface in FIG. 3) and prevent the denting or the like of the surface of the wooden decorative board 10 after the formation of the clear layer 28 described later, the undercoat layer 22 is provided to some extent. It is necessary to have the following thickness. For this reason, it is desirable that the undercoat layer 22 has a thickness of about 40 to 80 μm.

  Further, here, the isocyanate contained in the acrylic urethane paint (undercoat layer 22) forms a urethane bond with the hydroxyl group contained in the cellulose constituting the wood structure or fiber structure of the veneer 12 and the paint of the paint. A part will be in the state which digs into the uneven | corrugated | grooved part and hole which exist in the design surface 20 of the protrusion board 12, or a wood fiber, or is impregnated. Thus, the primer layer 22 is chemically bonded to the veneer 12 and, in addition, a sufficient anchor effect is exhibited. As a result, the undercoat layer 22 and the protruding plate 12 can be bonded extremely firmly chemically and physically.

  Then, as shown in FIG. 3B, the undercoat layer 22 is in an incompletely cured state that is not completely cured although it does not have fluidity. That is, the two-component curable acrylic urethane paint, which is a material for forming the undercoat layer 22, is mixed with a main agent (acrylic polyol) and a curing agent (polyisocyanate compound) and heated to cause a curing reaction. Proceeding to form the undercoat layer 22 made of a thermosetting acrylic urethane resin having a three-dimensional cross-linked structure. Therefore, the incompletely cured state of the undercoat layer 22 here means that the acrylic urethane resin does not flow plastically and has a degree of crosslinking of 100 regardless of whether the acrylic urethane resin is at room temperature or heated. It means a state of less than%.

Moreover, the crosslinking degree of acrylic urethane resin said here is calculated | required in the following way. First, an acrylic urethane resin having a weight of W ₀ is immersed in an ethyl acetate / butyl acetate mixed solution at 25 ° C. for 10 minutes, and then the solution containing the acrylic urethane resin is filtered with a filter paper. Thereafter, the insoluble matter on the filter paper is collected and vacuum-dried, and then the weight of the insoluble matter: W ₁ is precisely weighed. Then, the weighed have been insoluble content Weight: and W _1, the weight of initially immersed in ethyl acetate Butyl acetate mixed liquid acrylic urethane resin: By substituting W ₀ in the following equation, crosslinked The degree (% by weight) is required.
Crosslinking degree (% by weight) = (W ₁ / W ₀ ) × 100

  That is, by applying a two-component curable acrylic urethane paint, the veneer sheet 18 having the undercoat layer 22 formed on the design surface 20 of the veneer 12 is put into a hot air drying oven or the like, For example, the undercoat layer 22 is made fluid by performing a curing operation under conditions such as 50 ° C. × 30 minutes or 90 ° C. × 2 minutes, which is less than the standard curing condition of 50 ° C. × 1 hour. Is incompletely cured, with the degree of crosslinking of the undercoat layer 22 not reaching 100%. In addition, the hardening conditions which make the undercoat layer 22 an incomplete hardening state are suitably determined, considering the external appearance, quality, and performance of the wooden decorative board 10 finally obtained, for example. In addition, such a curing (heating) operation advantageously removes a solvent such as an organic solvent contained in the acrylic urethane paint.

  The specific value of the degree of crosslinking of the incompletely cured undercoat layer 22 (acrylic urethane resin) is not particularly limited, but the undercoat layer 22 is in an incompletely cured state. The degree of cross-linking is preferably about 85.0 to 99.9%. This is because when the degree of crosslinking of the acrylic urethane resin is less than 85.0%, the undercoat layer 22 is too soft, so that the surface of the undercoat layer 22 is formed when the adhesive layer 24 is formed, as will be described later. This is because the fluidity of the undercoat layer 22 may not be completely lost. On the other hand, when the degree of crosslinking of the acrylic urethane resin exceeds 99.9%, there are too few uncrosslinked parts. For this reason, as will be described later, when the acrylic syrup (38) is applied or the adhesive layer 24 At the time of formation, the acrylic resin in the uncrosslinked acrylic urethane resin (undercoat layer 22) and the acrylic syrup (38) or the acrylic resin in the adhesive layer 24 are mixed at the molecular level, in other words, compatible. This is because there is a risk of becoming insufficient. The degree of crosslinking of the undercoat layer 22 is more preferably about 85.0 to 99.0%, and more preferably about 85.0 to 95.0%.

  Next, as shown in FIG. 4, an acrylic syrup 38 is applied on the incompletely cured undercoat layer 22 by a known method. In addition, the application method of such an acrylic syrup 38 is not limited at all, For example, a roller, a brush, etc. are used for the acrylic syrup 38 with respect to the surface of the primer layer 22 in an incompletely cured state. Any of various known coating methods, such as coating or spray coating, are appropriately employed.

  The acrylic syrup used here is a known coating material. Specifically, a water-like polymerizable property in which a (meth) acrylic acid ester polymer (low molecular weight polymer) is dissolved in a radical polymerizable monomer. In this embodiment, a low molecular weight polymethyl methacrylate (PMMA), which is a polymer, is dissolved in a monomer, methyl methacrylate (MMA), and a polymerization accelerator is used as necessary. Although the thing which added additives, such as, is used, it is not limited to this at all.

  Here, since the undercoat layer 22 is in an incompletely cured state, the uncrosslinked acrylic resin in the undercoat layer 22 and the acrylic resin in the acrylic syrup 38 are the same or the same type of resin. Therefore, they are compatible and mixed at the molecular level in the vicinity of the surface portion of the undercoat layer 22. Therefore, the incompletely cured state of the undercoat layer 22 is preferably maintained at least until the application of the acrylic syrup 38 is completed, preferably until the polymerization (solidification) of the acrylic syrup 38 is completed. It should be noted that when the acrylic syrup 38 is applied under heating conditions, the heat of the coating may accelerate the curing of the undercoat layer 22, so care must be taken.

  Then, the adhesive layer 24 made of thermoplastic acrylic resin (PMMA) is formed by polymerizing (solidifying) the coated acrylic syrup 38. That is, by polymerizing the monomer methyl methacrylate (MMA), the acrylic syrup 38 is solidified, and the adhesive layer 24 made of polymethyl methacrylate (PMMA) is formed.

  Such a polymerization operation of the acrylic syrup 38 is performed, for example, by placing the veneer sheet 18 coated with the acrylic syrup 38 on the undercoat layer 22 into a hot air drying furnace or the like, for example, 90 to 120 ° C. × 10 to 10 ° C. It will be carried out under conditions of about 15 minutes. Depending on the kind of the polymerization accelerator contained in the acrylic syrup 38 for forming the adhesive layer 24, the curing can be completed without performing a special operation such as heating.

  In addition, simultaneously with the polymerization of the acrylic syrup 38 (formation of the adhesive layer 24), the undercoat layer 22 can be cured by heat at that time, whereby the undercoat layer 22 can be completely cured. Here, completely curing the undercoat layer 22 means that the undercoat layer 22 is made of a thermosetting acrylic urethane resin having a three-dimensional cross-linking structure by causing the curing reaction of the undercoat layer 22 to proceed. That is. The undercoat layer 22 only needs to be completely cured when the wooden decorative board 10 is completed. Accordingly, a process such as heating for completely curing the undercoat layer 22 can be performed separately after the formation of the adhesive layer 24. Further, the curing of the undercoat layer 22 can be promoted by using a molten resin or heat of the mold at the time of injection molding of the base material layer 30 and the clear layer 28 described later. Further, depending on the type of curing agent contained in the acrylic urethane paint for forming the undercoat layer 22, it is possible to completely cure the undercoat layer 22 without performing a special step such as heating. It is.

  And here, the acrylic resin in each layer in which the adhesive layer 24 thus formed and the fully cured undercoat layer 22 are the same or the same kind of resin in the vicinity of the interface between them. However, they are chemically and firmly bonded by being laminated in a state where they are mixed at the molecular level due to their compatibility. The adhesive layer 24 is generally formed with a thickness of about 20 to 60 μm in order to advantageously realize heat fusion with the clear layer 28 described later.

  Thus, as shown in FIG. 5, the bonding layer 16, the reinforcing layer 14, the protruding plate 12, the undercoat layer 22, and the adhesive layer 24 are constituted by a rectangular flat plate-like laminated structure in which the layers are formed in that order. The real wood sheet 26 is obtained.

  Next, the base material layer 30 is laminated on the back surface of the obtained main wood sheet 26 by injection molding, and further, the clear layer 28 is laminated on the surface of the main wood sheet 26 by injection molding. However, in order to form the base material layer 30 and the clear layer 28, various known methods such as a two-color molding method are adopted.

  Here, first, in one molding die (base material layer molding die) of the two-color molding apparatus, the base material layer 30 made of an opaque ABS resin is formed by injection molding, and the outer peripheral portion ( A covering layer 31 that covers the entire (end portion) is formed as a part of the base material layer 30. In addition, as a resin material for forming the base material layer 30, in addition to a general-purpose ABS resin, it is generally used as a material for forming automobile interior parts, for example, a polycarbonate / ABS resin or an ABS resin containing glass fibers. Thermoplastic resins such as polypropylene, polyethylene, polyamide, polybutylene terephthalate, and noryl resin can be used as appropriate.

  In such a formation process of the base material layer 30, when the base material layer 30 is injection-molded, a part of the synthetic resin constituting the base material layer 30 is uneven on the back surface of the joining layer 16 made of a rough wood board. It enters into the part, the hole, or between the wood fibers. As a result, the anchor effect is advantageously exerted, and the base material layer 30 is more strongly bonded to the bonding layer 16 and, consequently, to the main wood sheet 26 including the protruding plate 12. In addition, since the covering layer 31 formed of a part of the base material layer 30 is formed so as to cover the entire outer peripheral portion (end portion) of the main wood sheet 26, the covering layer 31 has a protruding plate. The contact with the air at the end of 12 is cut off. Furthermore, the base material layer 30 (covering layer 31) is made of an opaque ABS resin or the like, so that the end of the main wood sheet 26 cannot be seen from the outside.

  Next, with respect to the main wood sheet 26 on which the base material layer 30 is formed, a clear layer 28 made of a transparent acrylic resin is formed by injection molding in the other mold (clear layer molding mold) of the two-color molding apparatus. It is formed. In the method of the present invention, since it is a synthetic resin having transparency and can be thermally fused with the adhesive layer 24 made of a thermoplastic acrylic resin, a resin material for forming the clear layer 28 is used. It is also possible to use a polycarbonate resin.

  Here, at the time of injection molding of the clear layer 28, the injection-filled acrylic resin molten resin is thermally fused to the adhesive layer 24 made of thermoplastic acrylic resin. That is, the adhesive layer 24 is temporarily softened or melted by the heat of the molten resin, and the molten resin and the acrylic resin constituting the adhesive layer 24 are mixed at the molecular level. As a result, the clear layer 28 is firmly bonded to the adhesive layer 24. Further, the clear layer 28 is also fixed to the surface of the coating layer 31 formed of a part of the base material layer 30 by heat-sealing at the outer peripheral portion (end portion) of the joint surface with the adhesive layer 24. Thus, the target wood decorative board 10 having the structure as shown in FIG. 1 is obtained.

  Thus, in the woody decorative board 10 of the present embodiment, the veneer 12 and the clear layer 28 are firmly bonded chemically and physically through the undercoat layer 22 and the adhesive layer 24. Thereby, the peel strength of the clear layer 28 with respect to the protruding plate 12 is sufficiently and effectively increased. Therefore, even if the wooden decorative board 10 is used for a long period of time as an automobile interior part installed in a vehicle interior where a significant temperature change of 100 ° C. or more occurs from below freezing point, the clear layer 28 has the design of the projecting board 12. Such a feature that the separation from the surface 20 can be extremely effectively prevented is exhibited.

  Moreover, in such a wooden decorative board 10, when the acrylic syrup 38 is applied, the undercoat layer 22 is incompletely cured in a state where fluidity is lost. Further, when the clear layer 28 is injection-molded, the acrylic syrup 38 is already polymerized to form the adhesive layer 24, so that the adhesive layer 24 is bonded together with the molten resin forming the clear layer 28. It can also be avoided that the layer 24 flows. As a result, it is possible to effectively prevent a design mark from being deteriorated due to generation of a flow mark or the like in the adhesive layer 24 and the undercoat layer 22 that can be visually recognized from the outside through the clear layer 28.

  Further, in the present embodiment, a reinforcing layer 14 made of an aluminum thin plate is provided on the back surface of the projecting plate 12, and the rigidity of the main wood sheet 26 is advantageously increased as compared with that having no such reinforcing layer 14. It has been. As a result, the handling of the main wood sheet 26 is advantageously improved.

  Further, in the wood decorative board 10 of the present embodiment, the reinforcing layer 14 and the base material layer are disposed even though the reinforcing layer 14 made of an aluminum thin plate is interposed between the protruding plate 12 and the base material layer 30. Since the bonding layer 16 made of a wood plate having excellent adhesion to the base material layer 30 is interposed between the protrusion plate 12 and the base material layer 30, the protruding plate 12 and the base material layer 30 are firmly bonded. For this reason, even if the wooden decorative board 10 is used at a location where the temperature changes drastically even in the passenger compartment, the protruding board 12 and the base material layer 30 can be effectively prevented from peeling off.

  Furthermore, in this embodiment, prior to injection molding of the clear layer 28 on the design surface 20 side of the projecting plate 12 of the wood sheet 26, the base material layer 30 is formed on the back surface of the bonding layer 16 of the wood sheet 26. It is injection molded. For this reason, for example, unlike the case where the clear layer 28 is injection-molded before the injection molding of the base material layer 30, the bonding layer is formed by the injection pressure of the acrylic resin forming the clear layer 28 during the injection molding of the clear layer 28. It is advantageously avoided that the concavo-convex portions and hole portions present on the back surface of 16 are crushed, and therefore the anchor effect is reduced due to such crushed concavo-convex portions and hole portions. It is possible to prevent the bondability with respect to the bonding layer 16 from being lowered.

  Further, in the woody decorative board 10 of the present embodiment, the presence of the undercoat layer 22 impregnates the veneer 12 with resin, and the design of the veneer 12 is seen through due to light refraction, etc. The occurrence of this problem is advantageously prevented. That is, when the adhesive layer 24 is softened by the heat of the molten resin or mold during the coating of the acrylic syrup 38 by the undercoat layer 22 or during the injection molding of the base material layer 30 or the clear layer 28, the acrylic syrup is used. This is because it is advantageously prevented that the protruding plate 12 is impregnated with the acrylic resin constituting the adhesive layer 24.

  Then, since the adhesive layer 24 is made of a thermoplastic acrylic resin, the adhesive layer 24 adheres due to the passage of time from the formation of the main wood sheet 26, the influence of the molten resin and the heat of the mold when the base material layer 30 is formed, or the like. There is a feature that the bondability between the layer 24 and the clear layer 28 does not deteriorate. Furthermore, since there is no need to confirm the cured state of the adhesive layer 24 when forming the clear layer 28, the base layer 30 and the clear layer 28 are formed by a two-color molding method as in this embodiment. It becomes possible to implement efficiently.

  In the production of the wood decorative board 10 as described above, it is desirable to polish the surface of the undercoat layer 22 prior to the application of the acrylic syrup 38. However, in the undercoat layer 22, since the curing proceeds from the surface, as shown in FIG. 6 (a), the surface portion 22 a having a relatively fast curing (high cross-linking degree). As a result, the inner portion 22b having a relatively slow curing (low cross-linking degree) is formed. Therefore, by polishing the surface of the undercoat layer 22, the surface portion 22a is removed so that the inner portion 22b is exposed as shown in FIG. 6B. An acrylic syrup 38 is applied to the incompletely cured surface (undercoat layer 22) exposed in this manner, whereby uncrosslinked acrylic resin and acrylic in the undercoat layer 22 are applied. It is possible to effectively dissolve the acrylic resin in the syrup 38, and it is possible to further advantageously increase the bonding strength between the undercoat layer 22 and the adhesive layer 24. Further, by this polishing treatment, fine irregularities are formed on the surface of the undercoat layer 22, so that the anchor effect is exhibited and the bonding strength between the undercoat layer 22 and the adhesive layer 24 can be further increased. There is also the advantage of being able to do it.

  As described above, one of the representative embodiments of the present invention has been described in detail. However, this is merely an example, and the present invention is not limited by the specific description according to such an embodiment. It should be understood that this is not to be construed as limiting.

  For example, FIGS. 7A and 7B show another embodiment of a wooden decorative board manufactured according to the method of the present invention in a cross-sectional form. The wooden decorative board 40 according to the first embodiment is different from the wooden decorative board 40 according to the first embodiment except that a coating layer 42 obtained by curing a polyester urethane paint is formed on the surface of the veneer 12. 10 and a similar structure. Therefore, about the part made into the structure similar to the wooden decorative board 10 of 1st embodiment, suppose that detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  And since the polyester-type urethane paint used in order to form this coating-film layer 42 is a thing with comparatively low viscosity, as FIG.7 (b) shows, it exists in the surface of the veneer 12 It is possible to effectively fill the fine voids 44 to be performed. Therefore, it is possible to advantageously prevent or suppress the occurrence of unevenness on the surface of the clear layer 28 due to the void 44.

  Further, the isocyanate contained in the polyester-based urethane coating (coating layer 42) forms a urethane bond with a hydroxyl group contained in cellulose constituting the woody structure or fiber structure of the veneer 12 to form the coating layer 42. In addition, it is chemically bonded to the projecting plate 12, and in addition, a sufficient anchor effect is exhibited. As a result, the coating layer 42 and the projecting plate 12 are bonded extremely strongly chemically and further physically. And undercoat layer 42 will be formed on such a coat layer 42, but since coat layer 42 and undercoat layer 22 consist of the same urethane paint, it is urethane mutually. By joining, it comes to join firmly. For this reason, the formation (intervening) of the coating layer 42 does not reduce the peel strength of the undercoat layer 22, and thus the peel strength of the clear layer 28 does not significantly decrease. .

  Further, FIG. 8 shows another embodiment of the wood decorative board manufactured according to the method of the present invention in a cross-sectional form. The wooden decorative board 46 of the present embodiment is the same as that of the first embodiment except that the clear layer 48 is formed of polycarbonate resin and the hard coat layer 50 is formed on the clear layer 48. The structure is the same as that of the wooden decorative board 10 according to the embodiment. Therefore, about the part made into the structure similar to the wooden decorative board 10 of 1st embodiment, suppose that detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  In the embodiment shown in FIG. 8, since the polycarbonate resin is a resin material having high impact resistance, the impact resistance of the clear layer 48 is advantageously enhanced. However, the polycarbonate resin is excellent in impact resistance, but its hardness is low, so that the scratch resistance is not sufficient, and the surface of the clear layer 48 is easily damaged. By forming the hard coat layer 50 having a high thickness, the surface of the clear layer 48 is protected.

  In this case, the hard coat layer 50 is preferably formed of a colorless and transparent resin coating, and as the resin paint for forming the hard coat layer 50, a polyurethane resin paint or an acrylic resin paint Clear paints such as amino alkyd resin paints can be exemplified. In addition, the formation of the hard coat layer 50 is not limited to the above-described coating using a paint, and for example, a known layer forming method such as injection molding of an acrylic resin can be employed.

  The reinforcing layer 14 is preferably composed of a thin metal plate having high heat conductivity, among the materials as described above. By doing so, the base layer 30 and the clear layer as described above are preferable. At the time of injection molding of the layer 28, heat of the molten resin is transmitted to both the injection mold and the reinforcing layer 14, thereby causing a problem such as discoloration of the design surface 20 of the protruding plate 12 due to thermal influence. Occurrence of this can be effectively prevented. However, such a reinforcing layer 14 is not essential in the present invention and can be omitted.

  The material of the bonding layer 16 is not particularly limited as long as the bonding layer 16 has higher bonding property or adhesion to the synthetic resin base material layer 30 than the reinforcing layer 14. Therefore, when the reinforcing layer 14 is made of a thin metal plate, as the bonding layer 16, for example, a natural woven fabric made of cotton, or a fiber sheet knitted with glass fiber or carbon fiber, or various nonwoven fabrics, It can be used instead of a wooden board. Further, when the reinforcing layer 14 is composed of various woven fabrics, nonwoven fabrics, or the like, or when the reinforcing layer 14 is not provided, the bonding layer 16 can be omitted. Of course, there is no problem even if the bonding layer 16 is made of a known adhesive.

  Further, when the covering layer 31 formed integrally with the base material layer 30 is fixed to the surface of the clear layer 28 on the protruding plate 12 side (the lower side in FIG. 1) as in the illustrated embodiment, As the material for forming the material layer 30, among the thermoplastic resins exemplified above, a transparent resin material (acrylic resin or polycarbonate resin) that forms the clear layer 28 and a resin material that is favorably heat-sealed, specifically, ABS resin, polycarbonate / ABS resin, glass fiber reinforced ABS resin and the like are advantageously used.

  Furthermore, it is possible to add and mix a predetermined pigment into the acrylic urethane paint forming the undercoat layer 22 so that the undercoat layer 22 is colored. Therefore, the undercoat layer 22 is formed in a transparent state using a transparent acrylic urethane paint, and an acrylic mixed with a pigment is added and mixed on the surface of the undercoat layer 22 opposite to the protruding plate 12 side. A colored layer made of a urethane paint may be further formed. In this case, the acrylic syrup 38 is applied with the colored layer in an incompletely cured state. Further, the projecting plate 12 may be dyed by a known method, or the design surface 20 of the projecting plate 12 may be soaked with a pigment by wiping or the like.

  Desirably, the injection molding operation of the base material layer 30 is performed prior to the injection molding operation of the clear layer 28.

  In addition, the technique of the present invention can be advantageously applied to any wooden decorative board used as a skin material for various articles such as furniture, building materials, and home appliances in addition to automobile interior parts.

  In addition, although not enumerated one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

10, 40, 46 Wood veneer 12 Veneer 22 Undercoat layer 24 Adhesive layer 26 Main wood sheet 28, 48 Clear layer 30 Base material layer 38 Acrylic syrup 42 Coating layer 50 Hard coat layer

Claims (4)

A synthetic resin base material layer is laminated by injection molding on the back side of the wooden veneer that gives the design surface, while a clear layer made of transparent synthetic resin is laminated by injection molding on the front side of the veneer. A method for manufacturing a wooden decorative board,
A step of applying an acrylic urethane paint to the surface side of the protruding plate to form an incompletely cured undercoat layer;
A step of forming an adhesive layer made of a thermoplastic acrylic resin by further applying and polymerizing acrylic syrup on the incompletely cured undercoat layer formed on the surface side of the protruding plate; ,
A step of completely curing the primer layer simultaneously with or after the formation of the adhesive layer;
A step of laminating and forming the base material layer by injection molding on the back side of the veneer plate in which the undercoat layer and the adhesive layer are formed,
A step of laminating and forming the clear layer on the adhesive layer on the surface side of the veneer on which the base material layer is laminated, by injection molding of acrylic resin or polycarbonate resin,
The manufacturing method of the wooden decorative board characterized by including.   The surface of the undercoat layer in an incompletely cured state formed on the surface side of the protruding plate is polished, and the acrylic syrup is applied to the surface exposed by the polishing operation. Of manufacturing wooden decorative board.   The woody makeup according to claim 1 or 2, wherein a coating layer made of a polyester-based urethane coating is formed on the surface of the protruding plate, and the undercoat layer is formed on the coating layer. A manufacturing method of a board. The method for producing a wooden decorative board according to any one of claims 1 to 3, wherein the clear layer is formed of a polycarbonate resin, and a hard coat layer is further formed on the clear layer.

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