Photographic paper substrate and preparation method thereof, silver salt photographic paper

Abstract

The present application relates to the field of imaging technology, and discloses a photographic paper substrate and a preparation method thereof, and a silver salt photographic paper. The photographic paper substrate comprises: a substrate, the substrate comprises polyethylene terephthalate; a sealing layer, the sealing layer is arranged on the developing surface side of the substrate; the sealing layer comprises an upper sealing layer and a lower sealing layer, the lower sealing layer is arranged between the upper sealing layer and the substrate, the upper sealing layer comprises gelatin and a cross-linked resin, and the lower sealing layer comprises a cross-linked resin. Therefore, the silver salt photographic paper prepared from the photographic paper substrate proposed in the present application has good structural stability and chemical stability.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular, to a photographic paper substrate and a preparation method thereof, and silver salt photographic paper. Background Art

[0002] Traditional photography technology has been greatly impacted by the rapid development of digital technology and its dominance in the mainstream. However, in the field of professional photography, traditional silver halide photographic paper is still favored by many photographers due to its high resolution, rich tones and unique texture. In the field of artistic photography and collection, the durability and stability of silver halide photographic paper enable it to better display the artistic value of the work, making it one of the preferred media for preserving precious images. In order to adapt to market changes and meet consumer needs, silver halide photographic paper technology is also constantly innovating and developing. Summary of the invention

[0003] In the first aspect of the present application, the present application proposes a photographic paper substrate, comprising: a substrate, the substrate comprising polyethylene terephthalate; a sealing bottom layer, the sealing bottom layer being arranged on the developing surface side of the substrate; the sealing bottom layer comprising an upper sealing bottom layer and a lower sealing bottom layer, the lower sealing bottom layer being arranged between the upper sealing bottom layer and the substrate, the upper sealing bottom layer comprising gelatin and a cross-linked resin, and the lower sealing bottom layer comprising a cross-linked resin.

[0004] Therefore, the photographic paper substrate proposed in the present application includes a sealing layer arranged on one side of the developing surface of the substrate, and the sealing layer includes an upper sealing layer and a lower sealing layer. The upper sealing layer can strengthen the connection between the photographic paper substrate and the developing coating coated on the side of the upper sealing layer away from the substrate, and reduce the falling off of the developing coating. The lower sealing layer can strengthen the connection between the substrate and the upper sealing layer and the developing coating, improve the strength and flatness of the photographic paper substrate, and reduce curling and edge collapse. Therefore, the silver salt photographic paper prepared from the photographic paper substrate proposed in the present application has good structural stability and chemical stability.

[0005] In some embodiments, the cross-linked resin includes at least one of acrylic resin, ethylene-acrylic acid copolymer, polyurethane, styrene-propylene copolymer, styrene-butadiene rubber, and polyacrylate. The cross-linked resin has good pH stability and water resistance, and has a certain hardness. Therefore, the use of the cross-linked resin is conducive to improving the stability of the photographic paper substrate.

[0006] In some embodiments, the thickness of the upper sealing layer is 0.1 μm-5 μm. When the thickness of the upper sealing layer is within the aforementioned range, a film-like structure including cross-linked resin and gelatin can be formed, which has good smoothness, thereby facilitating the stability of the connection between the developing coating and the photographic paper substrate.

[0007] In some embodiments, the thickness of the bottom sealing layer is 0.1 μm-2 μm. Therefore, the bottom sealing layer includes a cross-linked resin, which has high chemical stability, is beneficial to protecting the substrate, reducing the impact of chemical substances on the stability of the photographic paper substrate during the development process, and is beneficial to improving the structural stability of the photographic paper substrate, which is beneficial to the long-term preservation of the silver salt photographic paper containing the photographic paper substrate.

[0008] In some embodiments, the invention further comprises: an antistatic layer, the antistatic layer is arranged on the side of the substrate away from the bottom cover, and the thickness of the antistatic layer is 0.1 μm-5 μm. Thus, the antistatic layer is arranged on the side of the substrate away from the bottom cover to improve the conductivity of the substrate, so that the static electricity generated during transportation or use is quickly conducted, reducing the current caused by static electricity, which is conducive to reducing the interference of static electricity on photosensitive imaging.

[0009] In some embodiments, the antistatic layer includes at least one of alkyl sulfonate, sulfate, betaine, sodium oligostyrene sulfonate, and sodium polyethylene sulfonate, thereby improving the conductive properties of the surface of the photographic paper substrate, reducing the accumulation of static electricity, and thus reducing the development defects caused by static electricity.

[0010] In the second aspect of the present application, the present application proposes a method for preparing the photographic paper substrate proposed in the present application, comprising: applying a lower sealing bottom layer slurry on the developing surface of the substrate and performing a drying and curing treatment to prepare a lower sealing bottom layer, wherein the lower sealing bottom layer slurry includes a resin emulsion and a cross-linking agent; applying an upper sealing bottom layer slurry on a side of the lower sealing bottom layer away from the substrate and performing a drying and curing treatment to prepare an upper sealing bottom layer, wherein the upper sealing bottom layer slurry includes a resin emulsion, a cross-linking agent and gelatin.

[0011] The method for preparing a photographic paper substrate proposed in the present application is simple to operate, and the thickness and composition of the lower cover layer and the upper cover layer can be adjusted independently, which is conducive to preparing a photographic paper substrate with a stable structure and long-term preservation.

[0012] In some embodiments, the coating amount of the lower sealing layer slurry is 1g / m 2 -30g / m 2 This is conducive to the crosslinking agent and the resin emulsion forming a film on the surface of the substrate, and forming a bottom sealing layer with a dense structure and good smoothness.

[0013] In some embodiments, the coating amount of the upper sealing bottom layer slurry is 1g / m 2 -40g / m 2 This is conducive to the cross-linking agent, resin emulsion and gelatin forming an upper sealing bottom layer with a certain thickness that retains some gelatin active groups.

[0014] In some embodiments, the crosslinking agent includes at least one of an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, and a sulfoxide crosslinking agent. Thus, the aforementioned crosslinking agent is conducive to preparing a crosslinked resin with a high crosslinking density.

[0015] In some embodiments, the resin emulsion includes at least one of polyacrylic resin emulsion, ethylene acrylic resin emulsion, polyurethane resin emulsion, styrene acrylic emulsion, styrene butadiene latex, and polyacrylate emulsion. Thus, the resin emulsion can be used to prepare a sealing layer with a stable structure and uniform film layer.

[0016] In some embodiments, the mass ratio of the resin emulsion, the crosslinking agent, the solvent, the gelatin, and the water in the upper bottom layer slurry is (3-20):(0.01-1):(1-5):(1-15):(80-95). Thus, the upper bottom layer slurry has a more suitable solid content and viscosity, and has better adhesion and drying properties.

[0017] In some embodiments, the mass ratio of the resin emulsion, the crosslinking agent, the solvent, and the water in the lower sealing layer slurry is (3-20): (0.01-1): (1-5): (80-95). Thus, the lower sealing layer slurry has better crosslinking ability and drying performance.

[0018] In the third aspect of the present application, the present application proposes a silver salt photographic paper, comprising the photographic paper substrate proposed in the present application or the photographic paper substrate prepared by the method proposed in the present application.

[0019] The silver halide photographic paper proposed in the present application is not easily affected by environmental factors such as light, temperature, humidity, etc., and has good structural stability. Therefore, the silver halide photographic paper proposed in the present application has good stability and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 Schematic diagram of the structure of a photographic paper substrate in one embodiment of the present application.

[0022] Description of reference numerals:

[0023] Base material 1; lower sealing bottom layer 2; upper sealing bottom layer 3; antistatic layer 4. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0025] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0026] The terms "including" and "having" in the specification and claims of the present application and any modifications thereof are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0027] In the description of this application, regardless of whether the words "about" or "approximately" are used, all the numbers disclosed herein are approximate values. The value of each number may differ by less than 10% or a reasonable difference considered by those skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

[0028] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0029] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0030] Silver halide photographic paper is a traditional photographic paper with silver halide as the photosensitive material. When the silver halide crystals in the photosensitive layer of silver halide photographic paper are exposed to light, they absorb photons, allowing silver ions (Ag·) to gain energy, and some of the silver ions are reduced to silver atoms (Ag), which form a potential image after exposure. This process produces an invisible image pattern on the photographic paper with different numbers of silver atoms distributed, which can sense and record light very finely. The development process of silver halide photographic paper requires the assistance of a developer, which has a selective reduction effect on silver halide crystals with different exposure levels. In areas with large exposure, more unstable silver atoms are produced, and the chance of reacting with the developer is greater, and more silver particles are reduced, so a darker black will appear after development; while in areas with small exposure, fewer unstable silver atoms are produced, and the chance of reacting with the developer is smaller, and fewer silver particles are reduced, so a lighter gray will appear. In this way, the developer can accurately restore different gray levels of the image according to different exposure levels. In order to achieve a clear development effect on silver halide photographic paper, the development process needs to go through multiple infiltration and treatment processes in the liquid phase.

[0031] The photographic paper substrate is the supporting structure of silver halide photographic paper, providing physical support for the entire photographic paper including the photosensitive layer. The photographic paper substrate needs to have a certain thickness and strength to withstand the mechanical stress during the development process, reduce the occurrence of cracking or deformation of the photographic paper during operation, and maintain flatness and stiffness. These requirements are crucial to the appearance and preservation performance of the final photo.

[0032] Compared with the traditional substrate materials of silver-salt photographic paper, the polyethylene terephthalate (PET) substrate has higher stiffness and ultra-high gloss, especially after being coated with an emulsion layer, it can produce a strong mirror paper effect. The PET substrate is unstable under strong alkaline wet conditions, and the pH value of the wet processing environment for the later development treatment of silver-salt photographic paper is 10-11. In this environment, the PET substrate is prone to structural changes, such as curling or abnormal expansion or contraction, and the developing coatings such as the emulsion layer coated on the PET substrate are also prone to peeling or tearing, causing the silver-salt photographic paper layer to collapse and demold. In order to solve the above-mentioned problems, the present application adopts a sealing layer with a double-layer structure on the developing surface side of the substrate. Therefore, the photographic paper substrate and the silver-salt photographic paper containing the photographic paper substrate proposed in the present application have good dimensional stability and chemical stability, can maintain the stability of structure and chemical properties after the later development treatment, and have good durability and can be preserved for a long time.

[0033] In the first aspect of the present application, the present application proposes a photographic paper substrate, comprising: a substrate, the substrate comprising polyethylene terephthalate; a sealing bottom layer, the sealing bottom layer being arranged on the developing surface side of the substrate; the sealing bottom layer comprising an upper sealing bottom layer and a lower sealing bottom layer, the lower sealing bottom layer being arranged between the upper sealing bottom layer and the substrate, the upper sealing bottom layer comprising gelatin and a cross-linked resin, and the lower sealing bottom layer comprising a cross-linked resin.

[0034] refer to Figure 1 The photographic paper substrate proposed in the present application includes a sealing layer arranged on the side of the developing surface of the substrate 1, the sealing layer includes an upper sealing layer 3 and a lower sealing layer 2, and an antistatic layer 4 arranged on the side of the substrate 1 away from the sealing layer. The side of the upper sealing layer 3 facing away from the substrate 1 can be coated with a developing coating, and the developing coating includes a latex layer, and the latex layer contains silver halide and can be photosensitive to form an image. The latex layer coating contains gelatin, and the upper sealing layer 3 contains a cross-linked resin and gelatin. The gelatin has active groups, including amino groups and carboxyl groups. The active groups in the gelatin can enable the latex layer and the upper sealing layer 3 to form a chemical bond connection, making the combination between the two more firm. As the base structure of silver salt photographic paper, the photographic paper substrate needs to be developed and soaked in an alkaline developer. The setting of the upper sealing layer 3 can make the developing coating coated thereon more stable.

[0035] In the bottom layer, both the upper bottom layer 3 and the lower bottom layer 2 contain cross-linked resin, and the molecular chains in the cross-linked resin are more tightly bound, which can reduce the influence of the solvent on the structure of the photographic paper substrate in the wet processing environment of the developing treatment, reduce the liquid absorption of the photographic paper substrate, and improve the wet tensile strength of the photographic paper substrate. In addition, the cross-linked resin on the contact surface of the upper bottom layer 3 and the lower bottom layer 2 can be cross-linked, so that the substrate 1, the lower bottom layer 2, and the upper bottom layer 3 form a stably connected whole.

[0036] Therefore, the photographic paper substrate proposed in the present application is provided with an upper sealing bottom layer, which can strengthen the connection between the photographic paper substrate and the developer coating layer and reduce the falling off of the developer coating layer. The lower sealing bottom layer is provided to strengthen the connection between the substrate and the developer coating layer and the upper sealing bottom layer, increase the strength and flatness of the photographic paper substrate, and reduce curling and edge collapse. Therefore, the silver salt photographic paper prepared from the photographic paper substrate proposed in the present application has good structural stability and chemical stability.

[0037] In some embodiments, the cross-linked resin includes at least one of acrylic resin, ethylene-acrylic acid copolymer, polyurethane, styrene-propylene copolymer, styrene-butadiene rubber, and polyacrylate.

[0038] The cross-linked resin has good pH stability and water resistance within the above range, which is beneficial to improving the chemical stability of the photographic paper substrate, protecting the substrate in an environment with relatively stable humidity, and reducing the structural and component changes of the substrate. In addition, the cross-linked resin has a certain hardness, which can improve the structural stability of the photographic paper substrate. Therefore, the use of the cross-linked resin is beneficial to improving the stability of the photographic paper substrate.

[0039] In some embodiments, the thickness of the upper sealing layer is 0.1 μm-5 μm.

[0040] The thickness of the upper sealing layer is within the above range, and a film structure containing cross-linked resin and gelatin can be formed, which has good smoothness, thereby facilitating the stability of the connection between the developing coating and the photographic paper substrate.

[0041] In some embodiments, the thickness of the lower sealing layer is 0.1 μm-2 μm.

[0042] The lower sealing layer can form a film structure with a cross-linked resin on the surface of the substrate within the above range. The cross-linked resin has high chemical stability and can effectively reduce the influence of chemical substances on the substrate during the development process. The cross-linked resin in the lower sealing layer can also improve the hardness and toughness of the photographic paper substrate. Therefore, it is beneficial to protect the substrate, reduce the influence of chemical substances on the stability of the photographic paper substrate during the development process, and improve the structural stability of the photographic paper substrate, which is beneficial to the long-term preservation of the silver salt photographic paper containing the photographic paper substrate.

[0043] In some embodiments, the method further comprises: an antistatic layer, wherein the antistatic layer is disposed on a side of the substrate away from the bottom sealing layer, and the thickness of the antistatic layer is 0.1 μm-5 μm.

[0044] During the imaging process of silver halide photographic paper, the accumulation of static electricity can trigger a discharge phenomenon, causing local current to be generated in the developer coating. This local current can cause the photosensitive silver halide in the developer coating to be exposed, causing the silver halide photographic paper to have irregular spots or bad films. Therefore, the photographic paper substrate proposed in the present application is provided with an antistatic layer on the side of the substrate away from the bottom cover, which can improve the conductive properties of the photographic paper substrate, so that the static electricity generated during transportation or use is quickly conducted, reducing the current caused by static electricity, which is conducive to reducing the interference with photosensitive imaging caused by static electricity.

[0045] In some embodiments, the antistatic layer includes at least one of alkyl sulfonate, sulfate, betaine, sodium oligostyrene sulfonate, and sodium polyethylene sulfonate.

[0046] The antistatic layer includes the aforementioned substances, which can improve the microstructure of the surface of the photographic paper substrate, form a micro-electric field with anion and cation distribution, thereby conducting charges and reducing the accumulation of static electricity. At the same time, the aforementioned substances have a certain hygroscopicity, and can form an ultra-thin water film with a certain conductivity on the surface of the photographic paper substrate, thereby improving the conductivity of the surface of the photographic paper substrate. Therefore, it is beneficial to improve the conductive performance of the surface of the photographic paper substrate, reduce the accumulation of static electricity, and thus reduce the development defects caused by static electricity.

[0047] In the second aspect of the present application, the present application proposes a method for preparing the photographic paper substrate proposed in the present application, comprising: applying a lower sealing bottom layer slurry on the developing surface of the substrate and performing a drying and curing treatment to prepare a lower sealing bottom layer, wherein the lower sealing bottom layer slurry includes a resin emulsion and a cross-linking agent; applying an upper sealing bottom layer slurry on a side of the lower sealing bottom layer away from the substrate and performing a drying and curing treatment to prepare an upper sealing bottom layer, wherein the upper sealing bottom layer slurry includes a resin emulsion, a cross-linking agent and gelatin.

[0048] The method for preparing a photographic paper substrate proposed in the present application is simple to operate, and the thickness and composition of the lower cover layer and the upper cover layer can be adjusted independently, which is conducive to preparing a photographic paper substrate with a stable structure and long-term preservation.

[0049] In some embodiments, the coating amount of the lower sealing layer slurry is 1g / m 2 -30g / m 2 This is conducive to the crosslinking agent and the resin emulsion forming a film on the surface of the substrate, and forming a bottom sealing layer with a dense structure and good smoothness.

[0050] In some embodiments, the coating amount of the upper sealing bottom layer slurry is 1g / m 2 -40g / m 2 This is conducive to the cross-linking agent, resin emulsion and gelatin forming an upper sealing bottom layer with a certain thickness that retains some gelatin active groups.

[0051] In some embodiments, the crosslinking agent includes at least one of an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, and a sulfoxide crosslinking agent. The aforementioned crosslinking agent can react with the resin emulsion to form a crosslinked resin with a higher crosslinking density, and has good stability, which is conducive to reducing the occurrence of side reactions. Therefore, the aforementioned crosslinking agent is conducive to preparing a crosslinked resin with a high crosslinking density.

[0052] In some embodiments, the resin emulsion includes at least one of polyacrylic resin emulsion, ethylene acrylic resin emulsion, polyurethane resin emulsion, styrene acrylic emulsion, styrene butadiene latex, and polyacrylate emulsion. The aforementioned resin emulsion has good fluidity and certain adhesion, which is conducive to coating and preparing a sealing layer with a smooth surface. At the same time, the aforementioned resin emulsion has good film-forming properties and stability, which is conducive to preparing a film layer with uniform thickness and stable chemical properties. Therefore, the aforementioned resin emulsion can prepare a sealing layer with a stable structure and uniform film layer.

[0053] In some embodiments, the solvent includes at least one of methanol, ethanol, propanol, and isopropanol. The aforementioned solvent can effectively disperse the resin emulsion, the crosslinking agent, and the gelatin to prepare the upper and lower sealing layer slurry and the lower sealing layer slurry with good dispersibility and stability.

[0054] In some embodiments, the mass ratio of the resin emulsion, the crosslinking agent, the solvent, the gelatin, and the water in the upper bottom-sealing layer slurry is (3-20): (0.01-1): (1-5): (1-15): (80-95). The upper bottom-sealing layer slurry has a relatively suitable solid content and viscosity, and can be adhered to the surface of the lower bottom-sealing layer by coating. Through the drying and curing treatment, a crosslinking reaction occurs to form the upper bottom-sealing layer, and partial crosslinking occurs between the upper bottom-sealing layer and the lower bottom-sealing layer. As a result, the upper bottom-sealing layer slurry has a relatively suitable solid content and viscosity, and has good adhesion and drying properties.

[0055] In some embodiments, the mass ratio of the resin emulsion, the crosslinking agent, the solvent, and the water in the lower sealing layer slurry is (3-20): (0.01-1): (1-5): (80-95). As a result, the lower sealing layer slurry has better crosslinking ability and drying performance. In the third aspect of the present application, the present application proposes a silver salt photographic paper, including the photographic paper substrate proposed in the present application or the photographic paper substrate prepared by the method proposed in the present application.

[0056] The silver-salt photographic paper proposed in the present application has a firm connection between the photographic paper substrate and the developer coating, is not easily affected by environmental factors such as light, temperature, and humidity, and reduces the occurrence of adverse conditions such as the developer coating falling off. The silver-salt photographic paper can effectively reduce the occurrence of obvious shrinkage or expansion under different humidity and temperature conditions, thereby maintaining the dimensional accuracy of the silver-salt photographic paper and having good structural stability, so that it has good stability and durability.

[0057] The scheme of the present application is described below by specific examples. It should be noted that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in this area or the product instructions are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0058] Example 1-Example 4

[0059] Deionized water, organic solvent, resin and cross-linking agent are mixed uniformly according to the formula ratio of the lower sealing bottom layer slurry to make a slurry, and then coated on the white PET substrate after corona treatment and dried at 100°C for 5 minutes. Deionized water, organic solvent, resin, cross-linking agent and gelatin are mixed according to the formula of the upper sealing bottom layer slurry to make a slurry, and then coated on the dried lower sealing bottom layer and dried at 100°C for 1 minute.

[0060] The composition of the bottom layer slurry in Comparative Examples 1 to 3, and the formula composition of the upper sealing bottom layer slurry and the lower sealing bottom layer slurry in Examples 1 to 4 are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] Test method:

[0065] The photographic paper substrate was aged at 60° C. and 50% RH for 24 hours, and a developing coating was applied on the photographic substrate. After developing and rinsing, its wet strength and edge collapse were tested.

[0066] Wet strength test method: After washing the photographic paper substrate, use the needle of the wet strength tester to gradually increase the pressure from one side of the photographic paper substrate and move the needle at a constant speed, and record the pressure when it is continuously scratched, which is the wet strength.

[0067] Edge collapse test method: After development and rinsing, use a magnifying glass to observe whether there are obvious defects or cracks in the development coating at the edge to determine whether there is edge collapse.

[0068] Test results: See Table 2.

[0069] Table 2

[0070] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Wet resistance mN 0.45 0.47 0.44 0.48 0.28 0.26 / Edge collapse No edge chipping No edge chipping No edge chipping No edge chipping Collapse Collapse Edge collapse and film removal

[0071] It can be seen from Table 2 that compared with the traditional bottom sealing layers in Comparative Examples 1, 2 and 3, the photographic paper substrate with a double-layer structure of an upper bottom sealing layer and a lower bottom sealing layer proposed in the present application has higher moisture resistance and can reduce edge collapse after aging in a wet environment, indicating that the photographic paper substrate proposed in the present application has good structural stability and chemical stability.

[0072] In the present application, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0073] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A photographic paper substrate, characterized in that: include: a substrate comprising polyethylene terephthalate; A sealing layer, the sealing layer being arranged on the developing surface side of the substrate; The bottom sealing layer comprises an upper bottom sealing layer and a lower bottom sealing layer, wherein the lower bottom sealing layer is arranged between the upper bottom sealing layer and the substrate, the upper bottom sealing layer comprises gelatin and a cross-linked resin, and the lower bottom sealing layer comprises a cross-linked resin.

2. The photographic paper substrate according to claim 1, characterized in that: The cross-linked resin includes at least one of acrylic resin, ethylene-acrylic acid copolymer, polyurethane, styrene-propylene copolymer, styrene-butadiene rubber, and polyacrylate.

3. The photographic paper substrate according to claim 1 or 2, characterized in that: The thickness of the upper sealing layer is 0.1 μm-5 μm; and / or, The thickness of the lower sealing layer is 0.1 μm-2 μm.

4. The photographic paper substrate according to claim 1 or 2, characterized in that: Further including: The antistatic layer is arranged on a side of the substrate away from the bottom sealing layer, and the thickness of the antistatic layer is 0.1 μm-5 μm.

5. The photographic paper substrate according to claim 4, characterized in that: The antistatic layer comprises at least one of alkyl sulfonate, sulfate, betaine, sodium oligostyrene sulfonate and sodium polyethylene sulfonate.

6. A method for preparing the photographic paper substrate according to any one of claims 1 to 5, characterized in that: include: Applying a lower sealing layer slurry on the developing surface of the substrate and performing a drying and curing treatment to prepare a lower sealing layer, wherein the lower sealing layer slurry includes a resin emulsion and a cross-linking agent; The upper bottom sealing layer slurry is coated on a side of the lower bottom sealing layer away from the substrate and dried and cured to prepare the upper bottom sealing layer, wherein the upper bottom sealing layer slurry includes a resin emulsion, a cross-linking agent, and gelatin.

7. The method according to claim 6, characterized in that The coating amount of the lower sealing layer slurry is 1g / m 2 -30g / m 2 and / or, The coating amount of the upper sealing bottom slurry is 1g / m 2 -40g / m 2 .

8. The method according to claim 6, characterized in that The cross-linking agent includes at least one of an isocyanate cross-linking agent, an aziridine cross-linking agent, an epoxy cross-linking agent, and a sulfoxide cross-linking agent; and / or, The resin emulsion includes at least one of polyacrylic acid resin emulsion, ethylene acrylic acid resin emulsion, polyurethane resin emulsion, styrene acrylic emulsion, styrene butadiene latex, and polyacrylate emulsion.

9. The method according to claim 6, characterized in that The mass ratio of the resin emulsion, the crosslinking agent, the solvent, the gelatin and the water in the upper sealing bottom layer slurry is (3-20):(0.01-1):(1-5):(1-15):(80-95); and / or, The mass ratio of the resin emulsion, the crosslinking agent, the solvent and the water in the lower sealing layer slurry is (3-20):(0.01-1):(1-5):(80-95).

10. A silver halide photographic paper, characterized in that: The photographic paper substrate comprises the photographic paper substrate according to any one of claims 1 to 5, or the photographic paper substrate prepared by the method according to any one of claims 6 to 9.

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