Label release paper and preparation process thereof

Abstract

The invention relates to the technical field of papermaking, and particularly provides label release paper and a preparation method thereof.The label release paper sequentially comprises a release layer, a bottom coating layer and a base material paper layer from top to bottom, and the release layer comprises polydimethylsiloxane; the bottom coating layer comprises an organic silane coupling agent; the base material paper layer sequentially comprises a surface layer, a modified paper layer and a bottom layer from bottom to top; wherein the surface layer and the bottom layer are both glassine paper; the density of the glassine paper of the surface layer is 1.15-1.20 g / cm < 3 >; and the density of the glassine paper at the bottom layer is 1.05-1.10 g / cm < 3 >. Polydimethylsiloxane is selected as the release layer, the release force of the adhesive can be remarkably reduced due to the fact that polydimethylsiloxane has ultralow surface energy, and the crosslinked polydimethylsiloxane layer is high in chemical inertness, low in heat resistance and moisture migration resistance, not prone to migration after being stored for a long time and easy to form chemical combination with the bottom coating layer, so that the adhesive force is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of papermaking, in particular, the present application provides a label release paper and a preparation process thereof. BACKGROUND

[0002] Label release paper, also known as release paper, release paper, release paper, release paper, is a kind of paper coated with anti-sticking material on its surface, which is used to protect the adhesive material (such as self-adhesive label, adhesive tape, double-sided tape, etc.) from being contaminated and adhering in advance. When used, the user tears off the release paper and directly attaches the adhesive layer on the back to the target object.

[0003] At present, label release paper usually has a release coating containing silicon on the base paper to provide anti-sticking property, so that the adhesive material can be easily peeled off. However, there are often problems such as insufficient blocking property, incomplete crosslinking of silicon oil, and excessive coating of silicon oil, which leads to migration of silicon oil molecules into pressure-sensitive adhesive, resulting in decreased label adhesion and even falling off. Therefore, it is urgent to provide a label release paper and a preparation process thereof. SUMMARY

[0004] The present application aims to solve at least one of the above problems.

[0005] The present application provides a label release paper, which comprises, from top to bottom, a release layer, a primer layer and a base paper layer. The release layer comprises polydimethylsiloxane; the primer layer comprises an organosilane coupling agent; and the base paper layer comprises, from bottom to top, a surface layer, a modified paper layer and a bottom layer. The surface layer and the bottom layer are both glassine paper; the density of the glassine paper of the surface layer is 1.15-1.20 g / cm 3 ; and the density of the glassine paper of the bottom layer is 1.05-1.10 g / cm 3 .

[0006] In the above technical features, the thickness of the release layer is 0.6-1.2 µm; and / or the thickness of the primer layer is 0.15-0.65 µm; and / or the thickness of the base paper layer is 70-75 µm.

[0007] In any of the above technical features, in the base paper layer, the thickness of the surface layer is 10-12 µm; and / or the thickness of the modified paper layer is 40-45 µm; and / or the thickness of the bottom layer is 18-20 µm.

[0008] The present application also provides a preparation process of a label release paper, which is used to prepare the label release paper according to any of the above technical features. The preparation process comprises the following steps: S100, a multi-layer wet forming process is used to prepare a base paper layer having a surface layer, a modified paper layer and a bottom layer; S200, coating a primer coating on the upper surface of the base paper layer, and drying to obtain a paper material with a primer coating; S300, coating a release coating on the upper surface of the primer coating, and drying to obtain a label release paper; In S100, the surface layer includes bleached softwood pulp and bleached hardwood pulp, the modified paper layer includes bleached softwood pulp, bleached hardwood pulp, glass fiber short cut and shrinkage inhibitor, and the base layer includes bleached softwood pulp and bleached hardwood pulp.

[0009] In any of the above technical features, in the surface layer, the mass ratio of bleached softwood pulp to bleached hardwood pulp is (1.5-2.5):1; and / or in the modified paper layer, the mass ratio of bleached softwood pulp, bleached hardwood pulp, glass fiber short cut and shrinkage inhibitor is 1:(0.2-0.5):(0.01-0.2):(0.01-0.1); and / or in the base layer, the mass ratio of bleached softwood pulp to bleached hardwood pulp is 1:(3-9).

[0010] In any of the above technical features, the beating degree of the surface layer is 45-50°SR; and / or the beating degree of the modified paper layer is 40-45°SR; and / or the beating degree of the base layer is 35-40°SR.

[0011] In any of the above technical features, the preparation process of the primer coating includes: S201, heating pure water to 80-90℃, slowly adding polyvinyl alcohol powder, stirring while adding, until the polyvinyl alcohol powder is completely dissolved, cooling to room temperature to obtain a polyvinyl alcohol solution; S202, adding the aqueous polyurethane emulsion to the polyvinyl alcohol solution, mixing uniformly, then adding a crosslinking agent and adjusting the pH to 6.5-8.0 to obtain the primer coating.

[0012] In any of the above technical features, the preparation process of the primer coating includes: S301, adding polydimethylsiloxane to silane-modified epoxy soybean oil, stirring until mixed uniformly to obtain a mixed oil phase; S302, continue to stir the mixed oil phase, and add a catalyst during stirring, and perform defoaming treatment after stirring to obtain the release coating.

[0013] In any of the above technical features, the coating amount of the primer coating is 0.2-0.8g / m 2 ; and / or the coating amount of the release coating is 0.6-1.2g / m 2 .

[0014] In any of the above technical features, S100 and S200 further include: S110, performing corona treatment on the upper surface of the base paper layer; After corona treatment, the upper surface of the base paper layer has a dyne value of 38-46 dyne.

[0015] After the technical solution of the present application is adopted, the following technical effects can be achieved: 1. Polydimethylsiloxane is selected as the release layer because PDMS has ultra-low surface energy, which can significantly reduce the adhesive peeling force. The cross-linked PDMS layer has high chemical inertness, low heat resistance, and low moisture migration resistance, and is not easy to migrate during long-term storage. It is easy to form chemical bonding with the primer layer, thereby improving the adhesion; 2. The primer layer can improve the adhesion of silicone oil to the paper base, and at the same time, it can seal the paper pores to prevent silicone oil from penetrating, thereby improving the moisture resistance. An organosilane coupling agent is usually used as the main material of the primer layer. One end of the organosilane coupling agent is covalently bonded to PDMS, and the other end is bonded to cellulose or the primer layer. It can not only significantly improve the peeling resistance, but also improve the moisture resistance of the coating, thereby reducing the risk of silicone oil layer falling off in a high humidity environment; 3. The base paper layer includes, from bottom to top, a surface layer, a modified paper layer, and a bottom layer. The surface layer uses high-density glassine paper, which can provide a smooth and dense substrate for the primer layer, thereby reducing silicone oil penetration and improving surface strength and folding resistance. The bottom layer uses low-density glassine paper, which can ensure the overall thickness and stiffness, control the cost and weight, and is beneficial to absorbing stress and avoiding curling during processing, thereby serving as a processing buffer layer. DETAILED DESCRIPTION

[0016] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be further described in detail below with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0017] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0018] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below.

[0019] In the related art, the label release paper usually has a silicon-containing release coating layer coated on the base paper to provide anti-sticking property, so that the adhesive material can be easily peeled off. However, there are often problems such as insufficient sealing, incomplete cross-linking of silicone oil, and excessive coating of silicone oil, which leads to migration of silicone oil molecules into the pressure-sensitive adhesive, resulting in decreased label adhesion and even falling off.

[0020] Therefore, the present application provides a label release paper and a preparation method thereof, by setting a base paper layer with a symmetrical structure and additionally setting a primer layer between the base paper layer and the release layer, which can not only balance the coating adaptability, but also enhance the adhesion between the release layer and the base paper layer.

[0021] Specifically, the present embodiment provides a label release paper, which comprises, from top to bottom, a release layer, a primer layer and a base paper layer, the release layer comprises polydimethylsiloxane; the primer layer comprises an organic silane coupling agent; and the base paper layer comprises, from bottom to top, a surface layer, a modified paper layer and a bottom layer; wherein the surface layer and the bottom layer are both glassine paper.

[0022] Preferably, the release layer can form a low surface energy interface to ensure that the label can be easily peeled off, and polydimethylsiloxane (PDMS) is selected as the release layer because PDMS has ultra-low surface energy, can significantly reduce the adhesive peel force, and the crosslinked PDMS layer has high chemical inertness, low heat resistance, low moisture migration resistance, is not easy to migrate during long-term storage, is easy to form chemical combination with the primer layer, and can improve the adhesion; if the release layer is too thin, the silicone oil coverage is not complete, the release force is unstable, and if the release layer is too thick, the cost is increased and the release force is limited, therefore, the thickness of the release layer is preferably in the range of 0.6-1.2 µm; the primer layer can improve the adhesion of silicone oil and paper base, and at the same time, can seal the paper pores to prevent silicone oil from penetrating and improve moisture resistance; usually, an organic silane coupling agent is used as the main material of the primer layer, the organic silane coupling agent has amphiphilic properties, one end is covalently combined with PDMS, and the other end is combined with cellulose or the primer layer, which can not only significantly improve the peel-off resistance, but also improve the moisture resistance of the coating, reduce the risk of silicone oil layer falling off in a high-humidity environment, and the primer layer needs to be thin enough to reduce the cost, but it needs to ensure that the paper surface fiber pores are completely covered, and the thickness of the primer layer is usually in the range of 0.15-0.65 µm; the base paper forms a mechanical support skeleton, and at the same time, through density gradient design, the surface density, stiffness, printing adaptability and cost are balanced; in order to ensure the stiffness and mechanical strength, and adapt to the traction force of a high-speed labeling machine, the thickness of the base paper layer is usually in the range of 70-75 µm.

[0023] Further, the base paper layer comprises, from bottom to top, a surface layer, a modified paper layer and a bottom layer, the surface layer provides a smooth and dense substrate for the primer layer, and preferably, the density of the surface layer is 1.15-1.20 g / cm 3The surface layer of the glassine paper can reduce the penetration of silicone oil, improve the surface strength and folding resistance, and the surface layer needs to be thick enough to form a high-density surface layer to reduce the penetration of silicone oil, but attention should be paid to the fact that the surface layer cannot be too thick, too thick will increase the cost and affect the flexibility, therefore the thickness of the surface layer is in the range of 10-12 microns; the modified paper layer is the core mechanical support layer in the base paper layer, and the thickness determines the overall stiffness and strength, and therefore is preferably set in the range of 40-45 microns; the bottom layer guarantees the overall thickness and stiffness, and controls the cost and weight, and preferably adopts the glassine paper with a density of 1.05-1.10 g / cm 3 The glassine paper is beneficial to absorbing stress and avoiding curling in the processing process, and serves as a processing buffer layer, and the bottom layer with a suitable thickness can reduce the back friction damage, and if the thickness of the bottom layer is insufficient, the stiffness of the finished paper will be insufficient, and if the thickness is too thick, the weight and cost will be increased, therefore the thickness of the bottom layer is preferably set in the range of 18-20 microns.

[0024] In some embodiments of the present application, the preparation process of the label release paper comprises the following steps: S100, a multi-layer wet one-step forming process is adopted to prepare a base paper layer with a surface layer, a modified paper layer and a bottom layer; S200, a primer coating is coated on the upper surface of the base paper layer, and after drying, a paper material with a primer layer is obtained; S300, a release coating is coated on the upper surface of the primer layer, and after drying, a label release paper is obtained.

[0025] Preferably, in the preparation of the base paper, a multi-layer wet one-time forming can be used to lay different proportions of pulp at the paper machine forming net stage, once dehydrated and formed and naturally cross-linked between layers, wet-state fibers directly hydrogen bond, and later coating or drying is not easy to delaminate, reducing the internal stress of paper fibers caused by multiple heat treatments, avoiding poor interlayer adhesion caused by multiple drying, independent adjustment of the flow of each layer, which is conducive to the total thickness being stable in the range of 70-75 pm, the surface layer includes bleached softwood pulp and bleached hardwood pulp, and the mass ratio of bleached softwood pulp to bleached hardwood pulp is (1.5-2.5):1, softwood pulp provides long fibers, high strength and stiffness, suitable for the surface to withstand coating stress, hardwood pulp provides short fibers, good filling, and good surface smoothness, which is beneficial to the uniform spreading of the silicone release coating, more softwood pulp helps to improve the surface tensile strength and resistance to coating tension, but enough hardwood pulp is retained to maintain smoothness, and the beating degree is controlled in the range of 45-50°SR to reasonably maintain the surface density, increase the density, and thus form a suitable density of glassine paper; the modified paper layer includes bleached softwood pulp, bleached hardwood pulp, glass fiber short cut, and anti-shrinkage additives, and the mass ratio of bleached softwood pulp, bleached hardwood pulp, glass fiber short cut, and anti-shrinkage additives is 1:(0.2-0.5):(0.01-0.2):(0.01-0.1), softwood pulp provides the main skeletal strength, hardwood pulp fills the structure and improves the fiber interweaving density, the addition of glass fiber short cut can improve the thermal stability and dimensional stability, reduce thermal shrinkage during coating and drying, and the anti-shrinkage additive can inhibit the dimensional change under wet heat conditions, and the beating degree is controlled in the range of 40-45°SR to ensure fiber bonding, while leaving space for the dispersion of glass fiber in the pulp, avoiding excessive compaction leading to reduced absorbency, and further adding wet strength agent, filler and sizing agent in the modified paper layer to improve stiffness and water resistance, and giving the label release paper product better performance; the bottom layer includes bleached softwood pulp and bleached hardwood pulp, and the mass ratio of bleached softwood pulp to bleached hardwood pulp is 1:(3-9), more hardwood pulp can increase the smoothness of the back of the paper, facilitating the uniform spreading of printing or back glue, which is better than the bottom layer which does not need high strength but needs certain support to prevent curling, therefore only a small amount of softwood pulp needs to be added, and the beating degree is controlled in the range of 35-40°SR, which is lower than that of the upper layer, has certain buffering property, and can offset the coating stress of the upper layer to prevent warping.

[0026] Preferably, S100 and S200 also include S110, corona treatment of the upper surface of the base paper layer. Paper naturally has a certain waxiness, fiber hair, filler particles, etc. on the surface, which will cause the surface energy to be lower, resulting in subsequent coating of the primer coating difficult to spread and adhere uniformly. Corona treatment generates plasma through high-frequency high-voltage discharge, slightly oxidizes and roughens the surface, breaks the fiber molecular chain and generates polar groups such as hydroxyl and carboxyl groups, greatly improving the surface hydrophilicity and wettability. After corona treatment, the Darcy value of the upper surface of the base paper layer is 38-46 dyne. Within this range, the primer layer and the release layer can spread well and firmly combine with the paper base without damaging the structure of the paper base.

[0027] Further, after corona treatment, a primer coating is applied to the upper surface of the base paper layer, and the coating amount is 0.2-0.8 g / m 2 A primer layer with a thickness of 0.15-0.65 µm can be obtained, and the preparation process of the primer coating includes: S201, heat pure water to 80-90℃, slowly add polyvinyl alcohol powder, stir while adding, until the polyvinyl alcohol powder is completely dissolved, cool to room temperature to obtain a polyvinyl alcohol solution; S202, add the water-based polyurethane emulsion to the polyvinyl alcohol solution, mix well, then add the crosslinking agent and adjust the pH to 6.5-8.0 to obtain the primer coating.

[0028] Preferably, the polyvinyl alcohol (PVOH) has a high crystallinity, with a large number of hydrogen bonds between the molecular chains. At room temperature, it is almost insoluble in water and must be heated to 80-90℃ to break the intermolecular hydrogen bonds, allowing the molecular chains to relax and enter the water phase. If added all at once, it will form surface clumps, making it difficult for the particles to completely dissolve. Slowly adding and stirring can avoid clumping and ensure the formation of a transparent and uniform PVOH solution. The water-based polyurethane emulsion (WPU) is sensitive to temperature, and if the temperature exceeds 40℃, the latex particles may be damaged, the particle size may increase, and the coating may become rough. Therefore, the PVOH solution must be cooled before adding the WPU. The crosslinking agent can react with the hydroxyl, amino, or carboxyl groups in PVOH and WPU to form a three-dimensional network, significantly improving the water resistance, solvent resistance, and adhesion of the primer. Adjusting the pH to 6.5-8.0 can avoid damaging the molecular structure of PVOH and prevent WPU from hydrolyzing, ensuring the stability of the primer coating.

[0029] Preferably, a release coating is further applied to the primer layer to obtain a release layer. The coating amount of the release coating is usually 0.6-1.2 g / m 2 The thickness of the release layer is 0.6-1.2 µm, and the preparation process of the release coating includes: S301, add polydimethylsiloxane into silane modified epoxy soybean oil, stir until mixed evenly, to obtain a mixed oil phase; S302, continue to stir the mixed oil phase, and add a catalyst during stirring, and perform defoaming treatment after stirring is completed, to obtain a release coating.

[0030] Preferably, PDMS and silane modified epoxy soybean oil are first mixed, both of which are hydrophobic organic phases, and the first mixing can make PDMS fully dispersed in the organic oil phase, avoiding uneven reaction caused by early addition of the catalyst, PDMS preferably uses oligomeric hydroxyl PDMS and phenyl modified PDMS, the molecular terminal of the oligomeric hydroxyl PDMS has -OH, which can be crosslinked with a silane coupling agent or an epoxy group to form a dense silicon-oxygen network structure, the phenyl modified PDMS can improve thermal stability and ultraviolet stability, the silane modified epoxy soybean oil can improve the flexibility of the coating and realize certain chemical bonding with PDMS through condensation or addition reaction to improve migration resistance, the mass ratio of the oligomeric hydroxyl PDMS, the phenyl modified PDMS and the silane modified epoxy soybean oil is preferably 7:2:1, the catalyst needs to be added after the oil phase is mixed evenly, if the catalyst is added too early, crosslinking reaction will be triggered during stirring, causing the viscosity of the system to rise or even solidification in advance, resulting in construction failure, the catalyst preferably uses platinum catalyst or tin catalyst, the platinum catalyst is mainly used in high-end labels with color requirements, and the tin catalyst is mainly used in general industrial labels with low yellowing resistance requirements; the viscosity of the PDMS system is high and air is easily entrained during stirring, therefore, defoaming treatment is also needed to avoid pinholes and local peeling of the coating film, affecting the release performance and appearance.

[0031] Example 1 The embodiment provides a label release paper, a release layer of which comprises polydimethylsiloxane; a primer layer of which comprises an organic silane coupling agent; and a substrate paper layer of which comprises, from bottom to top, a surface layer, a modified paper layer and a bottom layer; the surface layer and the bottom layer are both glassine paper, and the difference between them lies in the thickness of each layer and the density of the surface layer and the bottom layer in the base paper, as shown in Table 1. Table 1 Example 2 The embodiment provides a preparation method of a label release paper, comprising the following steps: S100, a substrate paper layer with a surface layer, a modified paper layer and a bottom layer is prepared by using a multi-layer wet forming process; S200, a primer layer coating is coated on the top surface of the substrate paper layer, and the coating amount is 0.2 g / m 2 , and after drying, a paper material with a primer layer is obtained; S300, a release coating is coated on the top surface of the primer layer, and the coating amount is 0.6 g / m2 , after drying, a label release paper is obtained; In S100, the surface layer comprises bleached softwood pulp and bleached hardwood pulp, the mass ratio of the bleached softwood pulp and the bleached hardwood pulp is 1.5:1, the beating degree is 45°SR, the modified paper layer comprises bleached softwood pulp, bleached hardwood pulp, glass fiber short cut and shrinkage resistance aid, in the modified paper layer, the mass ratio of the bleached softwood pulp, the bleached hardwood pulp, the glass fiber short cut and the shrinkage resistance aid is 1:0.2:0.01:0.01, the beating degree is 40°SR, the bottom layer comprises bleached softwood pulp and bleached hardwood pulp, the mass ratio of the bleached softwood pulp and the bleached hardwood pulp is 1:3, the beating degree is 35°SR; S110, performing corona treatment on the upper surface of the base paper layer; After the corona treatment, the upper surface of the base paper layer has a dyne value of 46 dyne; The preparation process of the primer coating includes: S201, heating pure water to 80℃, slowly adding polyvinyl alcohol powder, stirring while adding, until the polyvinyl alcohol powder is completely dissolved, cooling to room temperature to obtain a polyvinyl alcohol solution; S202, adding the aqueous polyurethane emulsion to the polyvinyl alcohol solution, mixing uniformly, then adding a crosslinking agent and adjusting the pH to 6.5 to obtain a primer coating; The preparation process of the release coating includes: S301, adding polydimethylsiloxane to silane-modified epoxy soybean oil, stirring until mixed uniformly to obtain a mixed oil phase; S302, continuing to stir the mixed oil phase, and adding a catalyst during stirring, after stirring, performing defoaming treatment to obtain a release coating.

[0032] Example 3 The present embodiment provides a preparation method of a label release paper, comprising the following steps: S100, using a multi-layer wet one-step forming process to prepare a base paper layer having a surface layer, a modified paper layer and a bottom layer; S200, coating a primer coating on the upper surface of the base paper layer, the coating amount being 0.8g / m 2 , after drying, a paper material having a primer coating is obtained; S300, coating a release coating on the upper surface of the primer coating, the coating amount being 1.2g / m 2 , after drying, a label release paper is obtained; In S100, the surface layer comprises bleached softwood pulp and bleached hardwood pulp, the mass ratio of the bleached softwood pulp and the bleached hardwood pulp is 2.5:1, the beating degree is 50°SR, the modified paper layer comprises bleached softwood pulp, bleached hardwood pulp, glass fiber short cut and shrinkage inhibitor, in the modified paper layer, the mass ratio of the bleached softwood pulp, the bleached hardwood pulp, the glass fiber short cut and the shrinkage inhibitor is 1:0.5:0.1:0.1, the beating degree is 45°SR, the bottom layer comprises bleached softwood pulp and bleached hardwood pulp, the mass ratio of the bleached softwood pulp and the bleached hardwood pulp is 1:9, the beating degree is 40°SR; S110, performing corona treatment on the upper surface of the base paper layer; After the corona treatment, the upper surface of the base paper layer has a dyne value of 38 dyne; The preparation process of the primer coating includes: S201, heating pure water to 80°C, slowly adding polyvinyl alcohol powder, stirring while adding, until the polyvinyl alcohol powder is completely dissolved, cooling to room temperature to obtain a polyvinyl alcohol solution; S202, adding the aqueous polyurethane emulsion to the polyvinyl alcohol solution, mixing uniformly, then adding a crosslinking agent and adjusting the pH to 6.5 to obtain the primer coating; The preparation process of the release coating includes: S301, adding polydimethylsiloxane to silane-modified epoxy soybean oil, stirring until mixed uniformly to obtain a mixed oil phase; S302, continuing to stir the mixed oil phase, and adding a catalyst during stirring, and performing defoaming treatment after stirring to obtain the release coating.

[0033] Performance test The following performance tests were conducted on the label release paper in Example 1, and the comparative example was a common commercially available label release paper.

[0034] 180° peel force test: vertically paste a standard pressure-sensitive adhesive tape on the surface of the release paper sample with a length of 100 mm, roll back and forth 3 times with a 2 kg pressure roller, store at 23±2°C, 50±5%RH for 24h, fix the sample, measure the 180° peel force at a speed of 300mm / min, repeat 10 times and take the average value; Peel force retention rate test after heat aging: place the sample in an oven preheated to 150°C for 24h, cool to room temperature for 2h, then measure the peel force using the same method as the 180° peel force test, and calculate the retention rate; The test results are shown in Table 2.

[0035] Table 2 As can be seen from Table 2, the 180° peeling force of the sample in Example 1 is less than that of the comparative example, and the peeling force remains almost unchanged after heat aging, indicating that the label release paper of the present application is obviously superior to the comparative example in high temperature stability, i.e. the label release paper of the present application is easier to peel off, and has better thermal stability.

[0036] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "a specific embodiment", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0037] Although the present application is disclosed as above, the present application is not limited to this. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be defined by the scope defined by the claims.

Claims

1. A label release paper characterized by, The label release paper comprises, from top to bottom, a release layer, a primer layer and a substrate paper layer, The release layer comprises polydimethylsiloxane; The primer layer comprises an organosilane coupling agent; The substrate paper layer comprises, from bottom to top, a surface layer, a modified paper layer and a bottom layer; The surface layer and the bottom layer are both glassine paper; The density of the surface layer of the glassine paper is 1.15-1.20 g / cm 3 ; The density of the base layer of glassine paper is 1.05-1.10 g / cm 3 .

2. The label release paper according to claim 1, wherein, The thickness of the release layer is 0.6-1.2 µm; and / or The thickness of the primer layer is 0.15-0.65 µm; and / or The thickness of the substrate paper layer is 70-75 µm.

3. The label release paper according to claim 2, wherein In the substrate paper layer, The thickness of the surface layer is 10-12 µm; and / or The thickness of the modified paper layer is 40-45 µm; and / or The thickness of the bottom layer is 18-20 µm.

4. A process for the production of a label release paper for the production of a label release paper according to any one of claims 1 to 3, characterized in that, The preparation process comprises the following steps: S100, a multi-layer wet one-step forming process is used to prepare a substrate paper layer comprising the surface layer, the modified paper layer and the bottom layer; S200, a primer coating is applied to the upper surface of the substrate paper layer, and after drying, a paper material with a primer layer is obtained; S300, a release coating is applied to the upper surface of the primer layer, and after drying, the label release paper is obtained; In S100, the surface layer comprises bleached softwood pulp and bleached hardwood pulp, the modified paper layer comprises bleached softwood pulp, bleached hardwood pulp, glass fiber short cut and shrinkage resistance aid, and the bottom layer comprises bleached softwood pulp and bleached hardwood pulp.

5. The preparation process according to claim 4, wherein, In the surface layer, the mass ratio of the bleached softwood pulp to the bleached hardwood pulp is (1.5-2.5):1; and / or In the modified paper layer, the mass ratio of the bleached softwood pulp, the bleached hardwood pulp, the glass fiber short cut and the shrinkage resistance aid is 1:(0.2-0.5):(0.01-0.2):(0.01-0.1); and / or In the bottom layer, the mass ratio of the bleached softwood pulp to the bleached hardwood pulp is 1:(3-9).

6. The preparation process according to claim 5, wherein, The beating degree of the surface layer is 45-50°SR; and / or The beating degree of the modified paper layer is 40-45°SR; and / or The beating degree of the bottom layer is 35-40°SR.

7. The manufacturing process of claim 4, wherein, The preparation process of the primer coating comprises: S201, pure water is heated to 80-90℃, polyvinyl alcohol powder is slowly added while stirring until the polyvinyl alcohol powder is completely dissolved, and after cooling to room temperature, a polyvinyl alcohol solution is obtained; S202, the aqueous polyurethane emulsion is added to the polyvinyl alcohol solution, mixed uniformly, then a crosslinking agent is added and the pH is adjusted to 6.5-8.0 to obtain the primer coating.

8. The manufacturing process of claim 4, wherein, The preparation process of the release coating comprises: S301, polydimethylsiloxane is added to silane modified epoxy soybean oil, stirred until mixed uniformly to obtain a mixed oil phase; S302, the mixed oil phase is continuously stirred, a catalyst is added during stirring, and after stirring is completed, defoaming treatment is performed to obtain the release coating.

9. The production process according to claim 4, characterized in that, The coating amount of the base coating material is 0.2 to 0.8 g / m 2 ; and / or The coating amount of the release coating is 0.6-1.2 g / m 2 .

10. The production process according to claim 4, characterized in that, between the S100 and the S200, further comprising: S110, performing corona treatment on the upper surface of the base paper layer; after the corona treatment, the upper surface of the base paper layer has a 38-46 dyne of 38-46 dyne.

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