Preparation process of oil-proof translucent paper

Abstract

The present application relates to the field of paper technology, and specifically provides a process for preparing oil-proof translucent paper. In the process for preparing oil-proof translucent paper, a surface sizing agent is applied to the paper during the calendering process; the surface sizing agent comprises, by 100% by weight: 2‑5% carboxymethyl cellulose and its sodium salt, 1‑3% amino silicone oil emulsion, and the balance is water. The surface sizing agent of the present application may also include PVA and / or poly (meth) acrylic acid homopolymer or copolymer. The surface sizing agent of the present application can significantly improve the water resistance and oil resistance of the paper after being applied to the surface of the paper, and also has a certain effect on improving the tensile strength of the paper.

Description

Technical Field

[0001] The present application relates to the technical field of paper, and in particular to a preparation process of oil-proof translucent paper. Background Art

[0002] Surface sizing is a process in the processing of paper or paperboard. It is usually located at the end of the drying section of the paper machine. A layer of glue is sprayed on the paper sheet when it is not completely dry but has a certain strength. After the drying process, a layer of glue film is formed on the surface of the paper or paperboard, thereby achieving the purpose of changing the surface properties of the paper or paperboard, such as oil resistance, improving strength, etc.

[0003] In the prior art, a commonly used paper surface sizing agent is carboxymethyl cellulose (CMC), which has good film-forming properties and overall film transfer properties, and can form good sealing and oil resistance on the paper surface. However, CMC also has the problems of high viscosity and strong stickiness. Although the use of medium molecular weight CMC can partially solve the problem of high viscosity and strong stickiness, it still cannot be solved perfectly. Summary of the invention

[0004] In order to solve the technical problems of high viscosity and strong stickiness of CMC as a paper surface sizing agent in the prior art, the present application provides a preparation process of oil-proof translucent paper.

[0005] This application adopts the following technical solutions:

[0006] A process for preparing translucent paper for oil proofing, wherein a sizing agent is applied on the calendering process surface;

[0007] The surface sizing agent comprises, by weight, 100% of: 2-5% of carboxymethyl cellulose and its sodium salt, 1-3% of amino silicone oil emulsion, and the balance is water.

[0008] Preferably, the weight percentage concentration ratio of the carboxymethyl cellulose and its sodium salt to the amino silicone oil emulsion is 1:0.2-1.

[0009] Preferably, the viscosity of the carboxymethyl cellulose and its sodium salt at 2 wt % at 25° C. does not exceed 800 cps, and the degree of substitution is 0.6-0.85.

[0010] Preferably, the weight percentage of the amino silicone oil emulsion is 30-70%.

[0011] Preferably, the surface sizing agent further contains 1-3% polyvinyl alcohol.

[0012] More preferably, the degree of polymerization of the polyvinyl alcohol is 1000-2000, and the degree of alcoholysis is 98-99%.

[0013] Preferably, the surface sizing agent further contains 1-3% of poly(meth)acrylic acid homopolymer or poly(meth)acrylic acid copolymer.

[0014] More preferably, the molar ratio of (meth)acrylic acid in the polymerized monomers of the poly(meth)acrylic acid copolymer is not less than 65%.

[0015] Further preferably, the polymerizable monomer of the poly(meth)acrylic acid copolymer further comprises a general formula of CH 2 =CR 1 COOR 2 Acrylate monomers, wherein R 1 is selected from H or C1-C4 alkyl, R 2 Selected from C1-C18 alkyl or C1-C18 fluorine-substituted alkyl.

[0016] An oil-proof translucent paper is prepared by the preparation process of the oil-proof translucent paper described in any one of the above embodiments.

[0017] In summary, this application has at least the following beneficial effects:

[0018] 1. The surface sizing agent of the present application comprises carboxymethyl cellulose and its sodium salt and amino silicone oil emulsion, which solves the problems of high viscosity and strong stickiness caused by carboxymethyl cellulose and its sodium salt as surface sizing agents, and the surface sizing agent has lower viscosity and stickiness.

[0019] 2. The addition of amino silicone oil emulsion to the surface sizing agent of the present application was found to further improve the water and oil resistance of paper. This may be because the amino groups in the amino silicone oil produce strong hydrogen bonds with the carboxyl groups in carboxymethyl cellulose and its sodium salt, so that the hydrophobic polysiloxane structure in the amino silicone oil molecule can cover and coat the surface of the carboxymethyl cellulose and its sodium salt, facing outward, thereby improving the water and oil resistance of the paper.

[0020] 3. The surface sizing agent of the present application may further include a homopolymer or copolymer of polyvinyl alcohol and / or poly(meth)acrylic acid. Polyvinyl alcohol can allow the surface sizing agent to better penetrate into the interior of the paper structure, thereby improving the strength of the paper. The carboxyl group in the homopolymer or copolymer of poly(meth)acrylic acid can generate multiple hydrogen bonds with carboxymethyl cellulose and its sodium salt, and amino silicone oil, further improving the water and oil resistance of the paper. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below.

[0022] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0023] On the one hand, the present application provides a process for preparing oil-proof translucent paper, wherein a surface sizing agent is applied to the paper during a calendering process;

[0024] The surface sizing agent comprises 100% by weight: 2-5% carboxymethyl cellulose and its sodium salt, 1-3% amino silicone oil emulsion, and the balance is water.

[0025] Carboxymethyl cellulose is used as a surface sizing agent for paper. It has good film-forming properties and overall film transfer properties, and can form good sealing and oil resistance on the surface of paper. However, it also has problems of high viscosity and stickiness, which is not conducive to sizing. In the present application, amino silicone oil emulsion is added to the surface sizing agent, and it is found that the problems of high viscosity and stickiness caused by carboxymethyl cellulose and its sodium salt can be significantly reduced, and the waterproof and oil-proof properties of the paper can be improved after sizing on the surface of the paper. In the present application, the amount of the above-mentioned surface sizing agent used for sizing paper is 10-50Kg per ton of paper.

[0026] In a preferred embodiment of the present application, the weight percentage concentration ratio of carboxymethyl cellulose and its sodium salt to amino silicone oil emulsion is 1:0.2-1. The weight percentage concentration ratio of carboxymethyl cellulose and its sodium salt to amino silicone oil emulsion is controlled within the above range, and the effect between carboxymethyl cellulose and its sodium salt and amino silicone oil is better. More preferably, the weight percentage concentration ratio of carboxymethyl cellulose and its sodium salt to amino silicone oil emulsion is 1:0.2-0.6. For example, the weight percentage concentration ratio can be 1:0.2, 1:0.22, 1:0.25, 1:0.28, 1:0.3, 1:0.33, 1:0.35, 1:0.37, 1:0.4, 1:0.42, 1:0.45, 1:0.47, 1:0.5, 1:0.52, 1:0.55, 1:0.57, 1:0.6, etc.

[0027] In a preferred embodiment of the present application, the carboxymethyl cellulose and its sodium salt are medium viscosity carboxymethyl cellulose and its sodium salt, the viscosity of 2wt% at 25°C does not exceed 800cps, and the degree of substitution is 0.6-0.85. Further preferably, the viscosity of 2wt% at 25°C does not exceed 600cps, and further preferably, does not exceed 300cps. For example, the viscosity of 2wt% of carboxymethyl cellulose and its sodium salt at 25°C can be 100cps, 150cps, 180cps, 200cps, 230cps, 250cps, 270cps, 280cps, 300cps, etc. More preferably, the degree of substitution is 0.6-0.8, and even more preferably, the degree of substitution is 0.6-0.75. For example, the degree of substitution can be 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, etc.

[0028] In a preferred embodiment of the present application, the weight percentage of the aminosilicone oil emulsion is 30-70%. In the present application, the aminosilicone oil emulsion includes both conventional aminosilicone oil emulsion, i.e., aminosilicone oil emulsion with a milky white appearance, and aminosilicone oil microemulsion, i.e., aminosilicone oil emulsion with a translucent to transparent appearance. The ammonia value of the aminosilicone oil in the aminosilicone oil emulsion has an effect on the yellowing of paper. The higher the ammonia value, the easier the paper is to yellow. In order to achieve lower yellowing without affecting the performance of the surface sizing agent, the ammonia value can be 0.1-1.5, or further, the ammonia value can be 0.2-1.2. The aminosilicone oil emulsion of the present application can be obtained from commercially available products or made at home. A method for making a common amino silicone oil emulsion can be as follows: 100 parts by weight of amino silicone oil with a viscosity of 1000-10000 mPa.s at 25°C and an ammonia value of 0.2-1.2, 10 parts by weight of an emulsifier (which can be composed of Tween80 and Span80 in a weight ratio of 2:1-1:1) and 0.5 parts by weight of n-butanol are uniformly mixed, and 70-100 parts by weight of water are gradually added under high-speed stirring at 1200-2000 rpm. After the water is added, the stirring speed is adjusted to 200-300 rpm and stirring is continued for 10 minutes to obtain the emulsion.

[0029] In a preferred embodiment of the present application, the surface sizing agent may also contain 1-3% polyvinyl alcohol. Further adding polyvinyl alcohol (PVA) to the surface sizing agent may make the surface sizing agent more easily penetrate into the internal structure of the paper, thereby improving the tensile strength of the paper.

[0030] In a more preferred embodiment of the present application, the degree of polymerization of PVA is 1000-2000, and the degree of alcoholysis is 98-99%. For example, the degree of polymerization of PVA can be 1200, 1500, 1700, etc., and the specific PVA model can be PVA-1798, PVA-1799, etc.

[0031] In a preferred embodiment of the present application, the surface sizing agent may also contain 1-3% of poly(meth)acrylic acid homopolymer or poly(meth)acrylic acid copolymer. The surface sizing agent of the present application further contains poly(meth)acrylic acid homopolymer or poly(meth)acrylic acid copolymer, which has good water solubility and can be dissolved in the sizing agent, and the carboxyl groups therein can form good hydrogen bonding with the amino groups in the amino silicone oil and the carboxyl groups in the carboxymethyl cellulose and its sodium salt, so that the amino silicone oil, the poly(meth)acrylic acid homopolymer or the poly(meth)acrylic acid copolymer, and the carboxymethyl cellulose and its sodium salt can form multiple hydrogen bondings, and the three together improve the waterproof and oil-proof property of the surface sizing agent for paper and reduce the water absorption.

[0032] In a more preferred embodiment of the present application, the molar ratio of (meth) acrylic acid in the polymerized monomers of the poly(meth) acrylic acid copolymer is not less than 65%. The molar ratio of (meth) acrylic acid in the polymerized monomers of the poly(meth) acrylic acid copolymer is not less than 65%, and the copolymer has good water solubility. For example, the molar ratio of (meth) acrylic acid in the polymerized monomers of the poly(meth) acrylic acid copolymer can be 65%, 68%, 70%, 72%, 73%, 75%, 77%, 78%, 80%, 83%, 85%, 87%, 88%, 90%, 92%, 95%, 98%, etc.

[0033] In a further preferred embodiment of the present application, the polymerized monomer of the poly(meth)acrylic acid copolymer, in addition to (meth)acrylic acid, further comprises a general formula of CH 2 =CR 1 COOR 2 Acrylate monomers, wherein R 1 is selected from H or C1-C4 alkyl, R 2 Selected from C1-C18 alkyl or C1-C18 fluorine-substituted alkyl. The copolymer containing the above acrylate monomer structure as the hydrophobic structure is used, and the hydrophilic structure in the copolymer forms a hydrogen bond with amino silicone oil, carboxymethyl cellulose and its sodium salt, and the hydrophobic structure extends outward to provide a hydrophobic effect for the paper, which can further improve the water and oil resistance of the paper. In particular, when the hydrophobic structure of the copolymer contains a fluorine-containing alkyl structure, it can give the paper better water and oil resistance.

[0034] In the present application, the poly(meth)acrylic acid homopolymer can be prepared as follows: 50 parts by weight of (meth)acrylic acid is added to 100 parts by weight of water, stirred to dissolve, 3% by weight of (meth)acrylic acid initiator ammonium persulfate is added, the temperature is raised to 70±2°C, stirred to react for 6 hours, added to 2000 parts by weight of methanol for precipitation, and the precipitation is dried to obtain. Alternatively, before adding to methanol for precipitation, the reaction system is further concentrated by reduced pressure distillation or the like, for example, the concentration can be concentrated to 50wt%, 60wt%, etc.

[0035] In the present application, the poly(meth)acrylic acid copolymer can be prepared as follows: 50 parts by weight of (meth)acrylic acid is added to 100 parts by weight of water, stirred to dissolve, 3% of the weight of (meth)acrylic acid as an initiator ammonium persulfate is added, the temperature is raised to 70±2°C, stirred to react for 6 hours, and then the corresponding parts by weight of acrylate monomer (such as butyl acrylate, perfluorooctyl ethyl acrylate, perfluorohexyl ethyl acrylate) are added dropwise, the reaction is continued for 5 hours, and the mixture is added to 2500 parts by weight of methanol for precipitation, and the precipitate is dried to obtain the obtained mixture. Alternatively, before adding the mixture to methanol for precipitation, the reaction system is further concentrated by reduced pressure distillation or the like, for example, the concentration can be concentrated to 50wt%, 60wt%, etc.

[0036] On the other hand, the present application provides an oil-proof translucent paper, which is prepared by the preparation process of the oil-proof translucent paper described in any of the above embodiments.

[0037] The paper sizing agent of the present application can be used not only for translucent paper, but also for opaque paper and corrugated paper.

[0038] The technical solution of the present application is described in detail below in conjunction with the embodiments and comparative examples. Unless otherwise specified, the parts in the following embodiments and comparative examples are parts by weight.

[0039] Example 1

[0040] 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of emulsifier (composed of Tween80 and Span80 in a weight ratio of 1.2:1) and 0.5 parts of n-butanol were mixed evenly, and 100 parts of water were gradually added under high-speed stirring at 1500 rpm. After the water was added, the stirring speed was adjusted to 250 rpm and stirring was continued for 10 minutes to obtain an amino silicone oil emulsion.

[0041] Dissolve 4 parts of medium viscosity carboxymethyl cellulose CMC (viscosity 280 cps at 25° C. at 2 wt % concentration, degree of substitution 0.65) in 95 parts of water, add 1 part of the above amino silicone oil emulsion, stir and mix well to obtain a surface sizing agent.

[0042] Example 2

[0043] In Example 1, the amino silicone oil emulsion is adjusted to 2 parts, the water is adjusted to 94 parts, and the other steps remain unchanged.

[0044] Example 3

[0045] The surface sizing agent in Example 1 is dissolved by adding carboxymethyl cellulose and then adding 1 part of PVA-1798. The number of parts of water is adjusted to 94 parts, and finally the amino silicone oil emulsion is added. The other steps remain unchanged.

[0046] Example 4

[0047] In Example 3, the amount of PVA-1798 was adjusted from 1 part to 2 parts, the amount of water was adjusted to 93 parts, and the other steps remained unchanged.

[0048] Example 5

[0049] The surface sizing agent in Example 1 is prepared by adding carboxymethyl cellulose to dissolve it, then adding 1 part of methacrylic acid homopolymer, adjusting the amount of water to 94 parts, and finally adding amino silicone oil emulsion. The other steps remain unchanged.

[0050] Example 6

[0051] The surface sizing agent in Example 1 is dissolved by adding carboxymethyl cellulose, then adding 2 parts of methacrylic acid copolymer (polymerized monomers are composed of acrylic acid and perfluorohexyl ethyl acrylate in a molar ratio of 9:1), the number of water parts is adjusted to 93 parts, and finally the amino silicone oil emulsion is added, and the other steps remain unchanged.

[0052] Example 7

[0053] 100 parts of amino silicone oil with a viscosity of 2700 mPa.s at 25°C and an ammonia value of 0.8, 8 parts of emulsifier (composed of Tween80 and Span80 in a weight ratio of 1.3:1) and 0.5 parts of n-butanol were mixed evenly, and 150 parts of water were gradually added under high-speed stirring at 1500 rpm. After the water was added, the stirring speed was adjusted to 250 rpm and stirring was continued for 10 minutes to obtain an amino silicone oil emulsion.

[0054] Dissolve 5 parts of medium viscosity carboxymethyl cellulose (viscosity 280 cps at 25°C at 2 wt% concentration, degree of substitution 0.72) in 93 parts of water, add 2 parts of the above amino silicone oil emulsion, stir and mix well to obtain a surface sizing agent.

[0055] Example 8

[0056] Dissolve 5 parts of the medium-viscosity carboxymethyl cellulose in Example 7 in 91.5 parts of water, add 1.5 parts of methacrylic acid copolymer (polymerized monomers are composed of methacrylic acid and perfluorooctyl ethyl acrylate in a molar ratio of 8:2), stir to dissolve, then add 2 parts of the aminosilicone oil emulsion in Example 7, stir and mix evenly to obtain a surface sizing agent.

[0057] Comparative Example 1

[0058] 4 parts of the medium viscosity carboxymethyl cellulose of Example 1 were dissolved in 96 parts of water to obtain a surface sizing agent.

[0059] Comparative Example 2

[0060] 4 parts of the medium-viscosity carboxymethyl cellulose in Example 1 were dissolved in 95 parts of water, and 1 part of PVA-1798 was added, and the mixture was stirred and mixed to obtain a surface sizing agent.

[0061] Comparative Example 3

[0062] 4 parts of the medium-viscosity carboxymethyl cellulose in Example 1 were dissolved in 94 parts of water, and 2 parts of PVA-1798 were added, and the mixture was stirred and mixed to obtain a surface sizing agent.

[0063] Comparative Example 4

[0064] 4 parts of the medium-viscosity carboxymethyl cellulose in Example 1 were dissolved in 94 parts of water, and 2 parts of the methacrylic acid copolymer in Example 6 were added, and the mixture was stirred and mixed to obtain a surface sizing agent.

[0065] The raw material composition and viscosity (25° C.) of the surface sizing agent in Examples 1-8 and Comparative Examples 1-4 are shown in Table 1 below.

[0066] The viscosity was tested using a rotational viscometer NDJ-5S at a rotation speed of 6 rpm.

[0067] Table 1 Raw material composition and viscosity of surface sizing agent

[0068]

[0069]

[0070] It can be seen from the results in Table 1 that after the amino silicone oil emulsion is added to the surface sizing agent of the present application, the viscosity of the surface sizing agent can be significantly reduced, which is more conducive to construction.

[0071] Translucent paper is produced according to the following process: wood pulp, bagasse pulp, and bleached waste paper pulp are added to 5m 3The pulper cycle goes through the process of beating the pulp tank, beating (five disc refiners in series on the main line), pulping tank, adding chemical products, pulping tank, pulping tank, screen, pressing, drying, winding, moistening, calendering, packaging and storage.

[0072] In the production process of the above translucent paper, in the calendering process, 40 kg of the surface sizing agent of Examples 1-8 and Comparative Examples 1-4 were added per ton of paper.

[0073] Absorbency: Tested in accordance with GB / T1540-2002 “Determination of water absorption of paper and paperboard (Cobber method)”.

[0074] Oil resistance: Tested in accordance with GB / T 22805.2-2008 "Determination of oil resistance of paper and paperboard Part 2: Surface repulsion method".

[0075] Tensile strength: Tested in accordance with GB / T 12914-2008 “Determination of tensile strength of paper and paperboard”.

[0076] The results are shown in Table 2 below.

[0077] Table 2 Performance test

[0078]

[0079]

[0080] It can be seen from the data in Table 2 that the surface sizing agent of the present application can improve the water resistance and oil resistance of the paper after being applied to the surface of the translucent paper during the calendering stage, and the tensile strength is also improved to a certain extent.

[0081] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are mixed uniformly, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose CMC are dissolved in 95 parts of water, 1 part of the amino silicone oil emulsion is added, and the mixture is stirred uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1; the viscosity of the medium-viscosity carboxymethyl cellulose at 2wt% at 25°C is 280cps, and the degree of substitution is 0.

65.

2. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are uniformly mixed, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose CMC are dissolved in 94 parts of water, 2 parts of the amino silicone oil emulsion are added, and the mixture is stirred and mixed uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1; the viscosity of the medium-viscosity carboxymethyl cellulose at 2wt% at 25°C is 280cps, and the degree of substitution is 0.

65.

3. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are mixed uniformly, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose CMC are dissolved in 94 parts of water, 1 part of PVA-1798 is added, and finally 1 part of the amino silicone oil emulsion is added, and the mixture is stirred and mixed uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1; the viscosity of the medium-viscosity carboxymethyl cellulose at 2wt% at 25°C is 280cps, and the degree of substitution is 0.

65.

4. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are mixed uniformly, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose CMC are dissolved in 93 parts of water, 2 parts of PVA-1798 are added, and finally 1 part of the amino silicone oil emulsion is added, and the mixture is stirred and mixed uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1; the viscosity of the medium-viscosity carboxymethyl cellulose at a concentration of 2wt% at 25°C is 280cps, and the degree of substitution is 0.

65.

5. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are uniformly mixed, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose (CMC) are dissolved in 94 parts of water, 1 part of methacrylic acid homopolymer is added, and finally 1 part of the amino silicone oil emulsion is added, and the mixture is stirred and mixed uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1; the viscosity of the medium-viscosity carboxymethyl cellulose at a concentration of 2wt% at 25°C is 280cps, and the degree of substitution is 0.

65.

6. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process. The preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2100 mPa.s at 25°C and an ammonia value of 0.4, 10 parts of an emulsifier and 0.5 parts of n-butanol are mixed uniformly, 100 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 4 parts of medium-viscosity carboxymethyl cellulose (CMC) are dissolved in 93 parts of water, 2 parts of methacrylic acid copolymer are added, and finally 1 part of the amino silicone oil emulsion is added, and the mixture is stirred uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.2:1, the viscosity of the medium-viscosity carboxymethyl cellulose at a concentration of 2wt% at 25°C is 280cps, and the degree of substitution is 0.65; and the polymerization monomers of the methacrylic acid copolymer are composed of acrylic acid and perfluorohexylethyl acrylate in a molar ratio of 9:

1.

7. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process; the preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2700 mPa.s at 25°C and an ammonia value of 0.8, 8 parts of an emulsifier and 0.5 parts of n-butanol are mixed uniformly, 150 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 5 parts of medium-viscosity carboxymethyl cellulose are dissolved in 93 parts of water, and 2 parts of the amino silicone oil emulsion are added, and the mixture is stirred uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.3:1; the viscosity of the medium-viscosity carboxymethyl cellulose at 2wt% at 25°C is 280cps, and the degree of substitution is 0.

72.

8. A process for preparing oil-proof translucent paper, characterized in that: A surface sizing agent is applied to paper during a calendering process. The preparation method of the surface sizing agent is as follows: 100 parts of amino silicone oil with a viscosity of 2700 mPa.s at 25°C and an ammonia value of 0.8, 8 parts of an emulsifier and 0.5 parts of n-butanol are uniformly mixed, 150 parts of water are gradually added under high-speed stirring at 1500 rpm, and after the water is added, the stirring speed is adjusted to 250 rpm and the stirring is continued for 10 minutes to obtain an amino silicone oil emulsion; 5 parts of medium-viscosity carboxymethyl cellulose are dissolved in 91.5 parts of water, 1.5 parts of methacrylic acid copolymer are added, stirred to dissolve, and finally 2 parts of the amino silicone oil emulsion are added, stirred and mixed uniformly to obtain a surface sizing agent; wherein the emulsifier is composed of Tween80 and Span80 in a weight ratio of 1.3:1; the viscosity of the medium-viscosity carboxymethyl cellulose at a concentration of 2wt% at 25°C is 280cps, and the degree of substitution is 0.72; and the polymerization monomers of the methacrylic acid copolymer are composed of acrylic acid and perfluorooctylethyl acrylate in a molar ratio of 8:2.

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