Photocurable sheet and production method of photocurable sheet

Abstract

To provide a photocurable sheet capable of being stuck without a gap by conforming to irregularities of a substrate and capable of suppressing deterioration of workability due to stickiness of a resin, and to provide a production method of the photocurable sheet.SOLUTION: A photocurable sheet comprises: a first resin film; a second resin film; a photocurable resin layer comprising a photocurable resin and being arranged between the first resin film and the second resin film; and a first fiber layer arranged inside the photocurable resin layer and impregnated with the photocurable resin. In the photocurable resin layer, a second region contacting the second resin film has a hardness lower than that of a first region contacting the first resin film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photocurable sheet and a method for producing the photocurable sheet. [Background technology]

[0002] Conventionally, fiber sheet attachment methods have been used to repair and reinforce tunnels and bridges, prevent concrete spalling, and sewerage facilities, as well as to prevent concrete corrosion and reduce the roughness coefficient of concrete surfaces used to increase the flow rate of pipes and waterways. These methods involve attaching fiber sheets made of, for example, glass fiber, carbon fiber, or aramid fiber while impregnating them with resin.

[0003] In this fiber sheet application method, for example, after correcting unevenness on the concrete surface, a primer or undercoat is applied, and the fiber sheet is applied while impregnating it with resin (impregnating resin), and multiple fiber sheets are layered as needed while repeatedly impregnating them with resin. At this time, it is necessary to carefully degas the fiber sheet while applying it to prevent air bubbles from becoming trapped between the fiber sheet and the resin in the lower layer (undercoat or impregnating resin in the lower layer) and reducing adhesion.

[0004] For this reason, when this method is applied to concrete corrosion prevention measures for sewerage facilities, in particular, the thickness of the resin layer and the occurrence of pinholes have a significant impact on corrosion prevention performance, so the work requires skilled workers. However, the number of such skilled workers is decreasing due to the declining birthrate and aging population.

[0005] For this reason, for example, a construction method using so-called photocurable prepreg sheets has been put into practical use, in which a fibrous base material such as glass fiber is impregnated with a resin containing a photopolymerization initiator in advance at a factory or the like and formed into a sheet (see, for example, Patent Documents 1 and 2). This photocurable prepreg sheet is formed, for example, by impregnating a fibrous base material with a resin mixed with two types of photopolymerization initiators, and sandwiching the resin in an uncured state and the fibrous base material between light-transmitting films such as PET films.

[0006] Such a construction method using a photocurable prepreg sheet can be carried out by attaching a photocurable prepreg sheet produced in a factory or the like to the construction surface at the construction site and then curing it by irradiating it with, for example, visible light or ultraviolet light. This results in a uniform thickness, no pinholes, and makes it possible to implement concrete corrosion prevention measures easily and in a short period of time without the need for skilled workers. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3479202 [Patent Document 2] Japanese Patent Application Publication No. 186744 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the light-curing prepreg sheets of Patent Documents 1 and 2 are used, if the surface to be applied is significantly uneven, the entire light-curing prepreg sheet may not adhere to the surface, which may result in entrapped air bubbles or unbonded areas. If such entrapped air bubbles or unbonded areas occur, there is a concern that the corrosion protection of the applied surface may be poor.

[0009] On the other hand, if the resin hardness of the resin layer of the photocurable prepreg sheet is reduced so as to fill in these unevennesses on the construction surface, problems arise such as the resin layer flowing out during construction or variations in the thickness of the resin layer. In addition, to fill in unevenness on the construction surface, a putty-like resin is applied and then a photo-curing prepreg sheet is attached, but this process becomes complicated and the advantage of being able to complete the construction in a short period of time cannot be fully realized.

[0010] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a photocurable sheet that can conform to the irregularities of the surface to which it is attached, ensuring close contact without gaps, and that can prevent a decrease in workability due to stickiness of the resin, as well as a method for manufacturing the photocurable sheet. [Means for solving the problem]

[0011] In order to solve the above problems, the photocurable sheet and the method for producing the photocurable sheet according to one embodiment of the present invention propose the following means. (1) A photocurable sheet according to aspect 1 of the present invention comprises a first resin film, a second resin film, a photocurable resin layer made of a photocurable resin and arranged between the first and second resin films, and a first fiber layer arranged inside the photocurable resin layer and impregnated with the photocurable resin, wherein the photocurable resin layer has a second region in contact with the second resin film that is lower in hardness than a first region in contact with the first resin film.

[0012] (2) A second aspect of the present invention is the photocurable sheet of the first aspect, wherein the hardness of the photocurable resin layer gradually decreases from the first resin film side toward the second resin film side.

[0013] (3) A third aspect of the present invention is the photocurable sheet of the first or second aspect, wherein the first region of the photocurable resin layer is a gel, and the second region of the photocurable resin layer is a sol.

[0014] (4) A fourth aspect of the present invention relates to the photocurable sheet of any one of the first to third aspects, further comprising a second fiber layer between the first fiber layer and the first resin film.

[0015] (5) A fifth aspect of the present invention is the photocurable sheet of any one of the first to fourth aspects, wherein the photocurable resin layer contains a vinyl ester resin.

[0016] (6) A sixth aspect of the present invention is the photocurable sheet of any one of the first to fifth aspects, wherein the first fiber layer is impregnated with the photocurable resin that constitutes the photocurable resin layer.

[0017] (7) A seventh aspect of the present invention relates to the photocurable sheet of any one of the first to sixth aspects, wherein the first fiber layer contains glass fibers.

[0018] (8) In an eighth aspect of the present invention, in the photocurable sheet of any one of the first to seventh aspects, the first resin film and the second resin film are made of a light-transmitting resin.

[0019] (9) A ninth aspect of the present invention relates to the photocurable sheet of the eighth aspect, wherein the first resin film and the second resin film contain polyethylene terephthalate.

[0020] (10) A tenth aspect of the present invention is the photocurable sheet of any one of the first to ninth aspects, wherein the photocurable resin layer has a thickness in the range of 0.3 mm or more and 10 mm or less.

[0021] (11) A method for manufacturing a photocurable sheet according to an eleventh aspect of the present invention is a method for manufacturing a photocurable sheet according to any one of aspects 1 to 10, and includes at least a photocurable resin inflow step of injecting uncured photocurable resin onto the first resin film, a resin film placement step of placing the second resin film on top of the uncured photocurable resin, and a semi-curing step of irradiating the photocurable resin layer with electromagnetic waves to semi-cure the photocurable resin layer so that the second region has a lower hardness than the first region. In the photocurable sheet manufacturing method of aspect 11, the order in which the first resin film and the second resin film are arranged can be reversed. Also, the method can be applied to both a batch-type manufacturing process and a continuous-type manufacturing process.

[0022] (12) A twelfth aspect of the present invention relates to the method for producing a photocurable sheet of the eleventh aspect, wherein the semi-curing step is a step of irradiating electromagnetic waves from the first resin film side toward the photocurable resin layer.

[0023] (13) A twelfth aspect of the present invention relates to a method for producing a photocurable sheet, wherein in the method for producing a photocurable sheet of the eleventh aspect, the semi-curing step is a step of irradiating electromagnetic waves from the first resin film side and the second resin film side toward the photocurable resin layer, and the electromagnetic waves irradiated from the first resin film side have a higher irradiation intensity than the electromagnetic waves irradiated from the second resin film side. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a photocurable sheet that can conform to the unevenness of the surface to which it is attached, ensuring close contact without gaps, and that can suppress a decrease in workability due to stickiness of the resin, as well as a method for manufacturing the photocurable sheet. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic cross-sectional view showing a photocurable sheet according to one embodiment of the present invention. [Figure 2] 1 is a flowchart showing a step-by-step method for producing a photocurable sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, a photocurable sheet according to one embodiment of the present invention and a method for manufacturing the photocurable sheet will be described with reference to the drawings. Note that the following embodiment is specifically described to better understand the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality.

[0027] [Photo-curing sheet] FIG. 1 is a schematic cross-sectional view showing a photocurable sheet according to one embodiment of the present invention. The photocurable sheet (photocurable prepreg sheet) 10 of this embodiment comprises, for example, a first resin film 11 which is one of the resin films, a second resin film 12 which is the other of the resin films formed opposite the first resin film 11, a photocurable resin layer 13 sandwiched between the first resin film 11 and the second resin film 12, and a first fiber layer 14 arranged inside the photocurable resin layer 13 and impregnated with a photocurable resin.

[0028] The first resin film (surface protection film) 11 and the second resin film (back surface protection film) 12 are each peeled off from the photocurable resin layer 13 when using the photocurable sheet 10. The first resin film 11 and the second resin film 12 may be any film that can transmit electromagnetic waves, such as visible light and ultraviolet light, required to cure the photocurable resin layer 13 described below.

[0029] The first resin film 11 and the second resin film 12 may be made of, for example, PET (polyethylene terephthalate), acrylic resin, etc. In this embodiment, the first resin film 11 and the second resin film 12 are made of transparent PET films that are capable of transmitting visible light and ultraviolet light.

[0030] The thickness of the first resin film 11 and the second resin film 12 may be, for example, about 10 μm to 100 μm.

[0031] The photocurable resin layer 13 is made of a photocurable resin containing a polymerization initiator that can generate radicals and initiate polymerization when irradiated with, for example, visible light or ultraviolet light. Examples of the photocurable resin that makes up the photocurable resin layer 13 include vinyl ester resins and acrylic resins.

[0032] In this embodiment, epoxy (meth)acrylate diluted and dissolved with styrene, (meth)acrylate, etc. is used as the photocurable resin constituting the photocurable resin layer 13. Such vinyl ester resin before curing is, for example, a viscous liquid (resin liquid). The photocurable resin layer 13 may be formed to have a thickness in the range of, for example, 0.3 mm or more and 10 mm or less, preferably 0.5 mm or more and 3 mm or less.

[0033] The photocurable resin layer 13 of this embodiment is made by semi-curing the vinyl ester resin before curing so that the hardness is uneven in the thickness direction. Hereinafter, the photocurable sheet 10 including the semi-cured photocurable resin layer 13 will be referred to as the photocurable sheet 10 before use.

[0034] Specifically, the photocurable resin layer 13 includes a first region E1 in contact with the first resin film 11 and a second region E2 in contact with the second resin film 12. There is no clear boundary between the first region E1 and the second region E2, and they are conveniently defined at any position along the thickness direction of the photocurable resin layer 13. The second region E2 is formed by performing a pre-controlled semi-curing process so that the second region E2 has a lower hardness than the first region E1.

[0035] Ideally, the photocurable resin layer 13 is formed so that its hardness gradually decreases from the first resin film 11 side including the first region E1 toward the second resin film 12 side including the second region E2.

[0036] For example, the first region E1 of the photocurable resin layer 13 is in a gel state that has lost fluidity but retains elasticity due to semi-curing. Meanwhile, the second region E2 of the photocurable resin layer 13 is in a sol state that is fluid and putty-like (its shape can be freely changed) as the semi-curing is suppressed. These differences in state occur because the degree of curing of the photocurable resin layer 13 by light is varied along the thickness direction of the photocurable resin layer 13 during production of the photocurable sheet 10.

[0037] The first fiber layer (cloth, mat, etc.) 14 is formed inside the photocurable resin layer 13, for example, in the first region E1. Such first fiber layer 14 can be made of glass fiber, resin fiber, nonwoven fabric, or the like formed in a sheet shape. In this embodiment, glass fiber formed in a sheet shape is used as the first fiber layer 14. The first fiber layer 14 has fibers impregnated with the vinyl ester resin that constitutes the photocurable resin layer 13.

[0038] In addition, the first fiber layer 14 may be formed not only in the first region E1 described above but also in the second region E2 or spanning from the first region E1 to the second region E2, and the position where it is formed within the photocurable resin layer 13 is not limited.

[0039] Such a first fiber layer 14 maintains the shape of the photocurable resin layer 13, including the fluid sol-state portion such as the second region E2, in a sheet-like state when the photocurable sheet 10 is in its pre-use state, and also serves as a rib that improves the physical strength of the photocurable resin layer 13 after the photocurable sheet 10 has hardened.

[0040] It is also preferable that a second fiber layer (such as a surface mat) 15 is further formed on the photocurable resin layer 13. The second fiber layer 15 can be made of glass fiber, resin fiber, nonwoven fabric, or the like formed into a sheet, similar to the first fiber layer 14. In this embodiment, the second fiber layer 15 is made of glass fiber formed into a sheet.

[0041] The second fiber layer 15 serves to improve the surface strength of the photocurable resin layer 13 after the first resin film 11 is removed following curing of the photocurable sheet 10. The second fiber layer 15 may be formed to be thinner than the first fiber layer 14.

[0042] When using the photocurable sheet 10 configured as described above to perform corrosion protection on the inner wall surface (construction surface) of a sewer or the like, the worker first peels off the second resin film 12 of the photocurable sheet 10 before use from the photocurable resin layer 13 to expose the fluid second region E2 of the photocurable resin layer 13.

[0043] Next, the worker presses the second region E2 of the photocurable resin layer 13 against the inner wall surface to be anticorrosive-treated, and adheres the photocurable sheet 10 from which the second resin film 12 has been removed. At this time, because the photocurable resin is in a fluid sol state in the second region E2 of the photocurable resin layer 13, even if the inner wall surface has large irregularities, the photocurable resin in a sol state in the second region E2 flows along these irregularities, allowing the photocurable sheet 10 to adhere tightly to the inner wall surface without causing air entrapment or the like.

[0044] Furthermore, when adhering the photocurable sheet 10 in this manner, the photocurable resin in the first region E1 of the photocurable resin layer 13 on the first resin film 11 side of the photocurable sheet 10, where the worker performs pressing work by hand, is in a gel state with no fluidity, so the pressing work does not cause the photocurable resin to adhere to the worker's fingers, etc., and thus does not cause stickiness.

[0045] As described above, with the photocurable sheet 10 of this embodiment, even an ordinary worker, not just a skilled craftsman, can easily adhere the photocurable sheet 10 to an uneven application surface without any gaps. Furthermore, since the pressing side of the photocurable sheet 10 does not become sticky during such work, the photocurable sheet 10 can be efficiently attached to the application surface in a short time.

[0046] After the photocurable sheet 10 is attached to the surface to be treated, the photocurable resin layer 13 is completely cured along the thickness direction by irradiating it with electromagnetic waves, such as ultraviolet light, capable of completely curing the photocurable resin layer 13. This allows for the photocurable sheet 10 to be tightly attached to the surface to be treated to prevent corrosion. The first resin film 11 may be removed when the photocurable sheet 10 is attached to the application surface, or may be removed after the photocurable resin layer 13 has been completely cured.

[0047] [Method for manufacturing photocurable sheet] FIG. 2 is a flow chart showing the steps of a method for producing a photocurable sheet according to one embodiment of the present invention.

[0048] When manufacturing the photocurable sheet 10 of the embodiment shown in Fig. 1 described above, first, a PET film, which is the first resin film 11, is placed on a mold or the like. Then, a second fiber layer 15 and a first fiber layer 14, each made of glass fiber or the like, are placed on top of the first resin film 11 in that order, and a viscous photocurable resin liquid, which is a pre-cured photocurable resin, for example, a polymer produced by an addition reaction between epoxy resin and (meth)acrylic acid, diluted and dissolved with styrene monomer or the like, is poured into the mold (photocurable resin pouring step S1). This allows the second fiber layer 15 and the first fiber layer 14 to be impregnated with the photocurable resin liquid.

[0049] Next, a PET film, which is the second resin film 12, is placed on the upper surface of this resin liquid (resin film placement step S2).

[0050] In the above-described manufacturing process, the order in which the first resin film 11 and the second resin film 12 are arranged may be reversed. In this case, after the second resin film 12 is arranged, the first fiber layer 14 and the second fiber layer 15 are sequentially stacked on top of the second resin film 12, and then the photocurable resin is poured in.

[0051] Then, for example, electromagnetic waves, such as ultraviolet light, that cure the photocurable resin liquid are irradiated from the first resin film 11 side and the second resin film 12 side. At this time, ultraviolet light is irradiated from both sides until the curable resin liquid is semi-cured, with the output (irradiation intensity) of the ultraviolet light source on the first resin film 11 side being higher than the output (irradiation intensity) of the ultraviolet light source on the second resin film 12 side.

[0052] This forms a photocurable resin layer 13 having different degrees of curing along the thickness direction, such as a first region E1 in a gel state in contact with the first resin film 11 and a second region E2 in a sol state in contact with the second resin film 12 (semi-curing process S3).

[0053] In addition, in this semi-curing process S3, by irradiating electromagnetic waves only on the first resin film 11 side and adjusting the output, it is possible to take advantage of the property of electromagnetic waves attenuating along the thickness direction of the photocurable resin liquid as they become farther away from the incident surface, thereby forming a photocurable resin layer 13 with different degrees of curing along the thickness direction.

[0054] Through the above steps, the photocurable sheet 10 of this embodiment can be manufactured, which includes the semi-cured photocurable resin layer 13 and the first resin film 11 and second resin film 12 that sandwich it.

[0055] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Industrial Applicability]

[0056] According to the photocurable sheet of the present invention, by forming a photocurable resin layer with a difference in hardness along the thickness direction, the photocurable sheet can be easily adhered without gaps even to uneven surfaces, making it possible to easily and reliably perform anticorrosion treatment on concrete, etc., and therefore has industrial applicability. [Explanation of symbols]

[0057] 10...Photo-curable sheet (photo-curable prepreg sheet) 11...First resin film 12...Second resin film 13...Photocurable resin layer 14...First fiber layer 15...Second fiber layer E1…first area E2…Second area

Claims

1. a first resin film and a second resin film; a photocurable resin layer made of a photocurable resin and disposed between the first resin film and the second resin film; a first fiber layer disposed inside the photocurable resin layer and impregnated with the photocurable resin; A photocurable sheet, wherein the photocurable resin layer has a second region in contact with the second resin film that has a lower hardness than a first region in contact with the first resin film.

2. The photocurable sheet according to claim 1 , wherein the photocurable resin layer has a hardness that gradually decreases from the first resin film side toward the second resin film side.

3. The photocurable sheet according to claim 1 , wherein the first region of the photocurable resin layer is a gel, and the second region of the photocurable resin layer is a sol.

4. The photocurable sheet according to claim 1 or 2, further comprising a second fiber layer between the first fiber layer and the first resin film.

5. The photocurable sheet according to claim 1 or 2, wherein the photocurable resin layer contains a vinyl ester resin.

6. The photocurable sheet according to claim 1 or 2, wherein the first fiber layer is impregnated with the photocurable resin constituting the photocurable resin layer.

7. The photocurable sheet according to claim 1 or 2, wherein the first fiber layer contains glass fibers.

8. The photocurable sheet according to claim 1 or 2, wherein the first resin film and the second resin film are made of a light-transmitting resin.

9. The photocurable sheet according to claim 8 , wherein the first resin film and the second resin film contain polyethylene terephthalate.

10. The photocurable sheet according to claim 1 or 2, wherein the photocurable resin layer has a thickness in the range of 0.3 mm or more and 10 mm or less.

11. A method for producing the photocurable sheet according to claim 1 or 2, a photocurable resin pouring step of pouring an uncured photocurable resin onto the first resin film; a resin film disposing step of disposing the second resin film on an upper surface of the photocurable resin before hardening; a semi-curing step of irradiating the photocurable resin layer with electromagnetic waves to semi-cure the photocurable resin layer so that the hardness of the second region is lower than that of the first region.

12. The method for producing a photocurable sheet according to claim 11 , wherein the semi-curing step is a step of irradiating the photocurable resin layer with electromagnetic waves from the first resin film side.

13. 12. The method for producing a photocurable sheet according to claim 11, wherein the semi-curing process is a process of irradiating electromagnetic waves from the first resin film side and the second resin film side toward the photocurable resin layer, and the electromagnetic waves irradiated from the first resin film side have a higher irradiation intensity than the electromagnetic waves irradiated from the second resin film side.

14. A method for producing the photocurable sheet according to claim 1 or 2, a photocurable resin pouring step of pouring an uncured photocurable resin onto the second resin film; a resin film disposing step of disposing the first resin film on an upper surface of the photocurable resin before hardening; a semi-curing step of irradiating the photocurable resin layer with electromagnetic waves to semi-cure the photocurable resin layer so that the hardness of the second region is lower than that of the first region.

15. The method for producing a photocurable sheet according to claim 12 , wherein the semi-curing step is a step of irradiating the photocurable resin layer with electromagnetic waves from the first resin film side.

16. 13. The method for producing a photocurable sheet according to claim 12, wherein the semi-curing process is a process of irradiating electromagnetic waves from the first resin film side and the second resin film side toward the photocurable resin layer, and the electromagnetic waves irradiated from the first resin film side have a higher irradiation intensity than the electromagnetic waves irradiated from the second resin film side.

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