Preparation method of fluoride-free waterproof and oilproof paper

Abstract

The invention relates to the field of oil-proof paper, and discloses a preparation method of fluoride-free waterproof oil-proof paper, which comprises the following steps: preparing slurry, pulping, preparing auxiliary materials, preparing a paper machine, drying, performing soft pressing on a film transfer sizing machine and a calender by adopting a double-pressing-area soft calender, coiling, rewinding, packaging, warehousing and the like. According to the preparation method, the technical conditions of a papermaking process are optimized, and the fluorine-free oil-proof agent is developed and blended, so that the preparation of the fluorine-free water-proof and oil-proof paper is realized.

Description

Technical Field

[0001] The invention relates to the field of oil-proof paper, and in particular to a method for preparing fluorine-free water-proof and oil-proof paper. Background Art

[0002] As the application of oil-proof paper becomes more and more extensive, the demand is also increasing. However, the health problem is that the oil-proof paper contains a lot of fluorine. At present, almost all oil-proof papers on the market use fluoride as an oil-proof agent, such as the oil-proof paper with the authorization publication number CN101517018B. Scientists have proven that fluoride has a carcinogenic effect on the body. Through scientific research and technological innovation, it is very necessary to optimize the technical conditions of papermaking process, develop and formulate fluorine-free oil-proof agents, and develop a fluorine-free waterproof and oil-proof paper. Because most of the oil-proof papers used on the market require waterproof and oil-proof properties, for this reason, we will develop a fluorine-free waterproof and oil-proof paper. Summary of the invention

[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing fluorine-free waterproof and oil-proof paper.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing fluorine-free waterproof and oil-proof paper comprises the following steps:

[0006] S1 pulp: bleached kraft softwood pulp 40-60%, bleached kraft hardwood pulp 40-60%;

[0007] S2 beating: After the slurry is evenly mixed according to the ratio requirements, three double-disc mills are used in series for cyclic beating;

[0008] S3 auxiliary materials: (a) add cationic starch to the inlet pipe of the pulp preparation tank, with a weight ratio of 1.0-1.5%; (b) add a small amount of defoamer stock solution to the white water tank of the wire; (c) add neutral sizing agent to the inlet of the pulp pump, with a weight ratio of 1.0-1.5%; (d) add retention agent to the outlet pipe of the pressure screen, with a weight ratio of 0.02-0.04%;

[0009] S4 paper machine: control the main parameters of the paper machine;

[0010] S5 drying: It is divided into the front drying section and the rear drying section, with the sizing machine in the middle of the front drying section and the rear drying section;

[0011] S6 film transfer sizing machine: Add fluorine-free oil-proof coating and use double-sided coating, the front coating metering rod model: 21#, metering rod pressure 100kpa; the back coating metering rod model: 21#, metering rod pressure 100kpa; the coating single side is controlled at 0.3~1.0g / m 2, the paper tension in front of the sizing machine is 180N / m 2 , the tension of the paper sheet after the sizing machine is 160N / m 2 , to form a dense waterproof and oil-proof coating on the surface of the paper;

[0012] The S7 calender uses a double-nip soft calender for calendering;

[0013] S8 obtains the fluorine-free waterproof and oil-proof paper after winding, rewinding, packaging and storage.

[0014] Preferably, in step S2, the beating degree is 57±2°SR and the wet weight is 3.5-4.5 g.

[0015] Preferably, in step S3, the cationic starch is CS-8 cationic starch, the neutral sizing agent is AKD neutral sizing agent, and the retention aid is polymin sk retention aid.

[0016] Preferably, the main parameters of the paper machine in step S4 are: wire speed 200-220 m / min, width 1880 mm, headbox lip opening 9.8 mm, first press line pressure of the press section: 500 kN / m, second press line pressure: 550 kN / m; curling tension: 280 kN / m.

[0017] Preferably, in step S6, the concentration of the sizing agent is 10±0.5%, the temperature is 60±5°C, and the surface sizing coating amount is ≥0.3g / m2 on the front side and ≥0.3g / m2 on the back side.

[0018] Preferably, the fluorine-free oil-proof coating in step S6 is composed of a mixture of polyether-modified organic polysilazane and surface sizing agent CS-3, and the usage is 15-45 kg of polyether-modified organic polysilazane and 10 kg of surface sizing agent CS-3 per ton of paper.

[0019] No domestic enterprise has used this formula coating to produce fluorine-free oil-proof paper. The fluorine-free oil-proof coating used in the present invention is a mixed solution of polyether-modified organic polysilazane and a surface sizing agent (CS-3). For a variety of organic compounds with oleophobic properties selected, through laboratory research, the solutions of different organic compounds were coated on base paper for testing, countless oil-proof performance tests and comparisons, combined with the pros and cons of each experimental oil-proof performance, and the miscibility with water (easy operation), and then comprehensive cost factors were considered, and finally polyether-modified organic polysilazane was selected as the main component of the fluorine-free oil-proof coating. In order to further improve the waterproof performance of oil-proof paper, the coating experiment test and comparative analysis of the surface sizing agent (CS-3) were carried out, and the optimal ratio and dosage of the surface sizing agent (CS-3) were deployed, and the final coating formula of the fluorine-free oil-proof agent was determined, so that the oil-proof paper has excellent waterproof and oil-proof effects, even the waterproof effect to hot water is also very good.

[0020] Preferably, the preparation method of the polyether-modified organic polysilazane is: under an argon or dry air atmosphere, adding a Karl von Neumann catalyst into a three-necked flask containing allyl (propyl polyethylene glycol), stirring, and then adding polysilazane to react to obtain the polyether-modified organic polysilazane.

[0021] Preferably, the preparation method and conditions of the polyether-modified organic polysilazane are as follows: in the presence of a Carr catalyst (Pt), the allyl-PEO molecule is grafted onto the polysilazane (PSZ) chain through a hydrogenation reaction between the Si-H group of the polysilazane (PSZ) and the terminal C=C group bond of the polysilazane (PSZ); the most favorable conditions for the addition of the allyl-PEO chain onto the polysilazane (PSZ) are: in an argon atmosphere, 80° C., a molar ratio of the Carr catalyst (Pt) to the allyl group of 3×10 -3 .

[0022] The synthesis process of the main component of the self-made fluorine-free oil-proof coating, polyether-modified organic polysilazane, is unique and novel, with strong creativity. The fluorine-free oil-proof paper produced has a thin and uniform coating, good waterproof and oil-proof effect, environmental protection and easy recycling, etc. The single-sided coating amount is 0.3-1g / m 2 When the fluorine-free waterproof and oil-proof paper with oil-proof grades 3 to 7 can be prepared. At the same time, the Si-H / allyl molar ratios of three allyl-PEOs were studied, which were 10, 16.5 and 26.5, respectively. The grafted product is represented by PSZ-PEO XY, where X is the molecular weight of MPEG and Y is the Si-H / allyl molar ratio. Note that the larger the molecular weight of PSZ, the more difficult the hydrosilylation reaction is. In the presence of a Karl-Paul Schmidt catalyst, the allyl alcohol molecules are grafted onto the polysilazane (PSZ) chain by the hydrosilylation reaction between the binding group and the terminal binding group of PSZ. The catalyst Pt(dvs) was added to a 1X10 -3 or 3x10 -3 ) in a three-necked flask. After stirring for 15 minutes, PSZ (PSZ / [allyl-polyethylene glycol] molar ratio of 7, 10, 16.5 or 26.5) was added. The reaction took place under argon or dry air (in this case, the reaction flask was equipped with a long glass fitting containing anhydrous calcium chloride) and the reaction was stirred at 70, 80 or 85°C. The most favorable conditions were: under argon atmosphere, 80°C, and a molar ratio of the Pt catalyst to the allyl group of 3x10 -3 The reaction mechanism is shown below:

[0023]

[0024] The coordination structure of the Karlsruhe catalyst is as follows:

[0025]

[0026] Preferably, in step S6, the dryness of the finished paper entering the film transfer sizing machine is ≥95%; and the dryness of the finished paper exiting the film transfer sizing machine is ≥75%.

[0027] The present invention adopts a film transfer coating method: according to the requirements of the waterproof and oil-proof grade of paper, a fluorine-free oil-proof coating is first prepared according to the process requirements, and the surface is double-sided coated by a film transfer surface sizing machine. After drying, fluorine-free oil-proof paper with a waterproof effect can be prepared. The film transfer coating mainly makes the surface coating of the paper flat and forms a dense film with the characteristics of low air permeability and low water absorption.

[0028] Preferably, in step S7, the first pressing pressure is 50 kN / m, the second pressing pressure is 60 kN / m, the front surface smoothness is 40 to 50S, and the back surface smoothness is 50 to 70S.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The preparation method of the invention realizes the preparation of fluorine-free water-proof and oil-proof paper by optimizing the papermaking process technical conditions and coordinating the development, synthesis and preparation of fluorine-free oil-proof agent. DETAILED DESCRIPTION

[0031] The raw materials used in the examples are all commercially available unless otherwise specified. The polyether-modified organic polysilazane is self-synthesized, the surface sizing agent (CS-3) is provided by Zhejiang Chuanhua Huayang Chemical Co., Ltd., the cationic starch CS-8 is provided by Guangxi Mingyang, and the retention aid polymin sk is provided by BASF. The methods in the following examples are all conventional methods in the art unless otherwise specified. Although the preferred embodiments of the present application are described below, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the attached claims are interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0032] The production process of this fluorine-free waterproof and oil-proof paper is novel: the pulp is all made of sulphate bleached coniferous wood pulp and hardwood pulp, ensuring the cleanliness and food grade (no fluorescence) of the pulp, pulp (coniferous and hardwood) → chain conveyor → pulper → unloading tank → pulper → pulping tank → pulping tank → pulping tank → pre-sizing tank → sizing pump → pulping pump → desander → pressure screen → headbox → wire forming → pressing section → front drying section → film transfer sizing machine (fluorine-free oil-proof coating addition point) → rear drying section → soft calender → winding section → rewinding → finished product packaging and storage - fluorine-free waterproof and oil-proof paper finished product. Oil-proof paper has a wide range of uses, generally used in fast food packaging such as hamburgers, chicken wings and legs, French fries, pizza, etc. It can also be used as a base material for post-processing of baking paper, steamer paper, and barbecue paper. Its highest oil-proof level is 12, and the oil-proof level requirement for commonly used packaging oil-proof paper is 3-7.

[0033] Example 1: Grade 3 fluorine-free water-proof and oil-proof paper

[0034] A method for preparing fluorine-free waterproof and oil-proof paper comprises the following steps:

[0035] The pulp is a mixture of 50% bleached kraft softwood pulp and 50% bleached kraft hardwood pulp. After the pulp is evenly mixed, three double-disc mills are used for cyclic beating, with a beating degree of about 56°SR and a wet weight of about 4.0g. The amounts of auxiliary materials to the absolute dry pulp are as follows: cationic starch CS-8 is added to the inlet pipe of the pulp preparation tank, with a weight ratio of 1.0%; a small amount of defoamer stock solution is added to the white water tank of the wire, with a weight ratio of 0.012% (the amount added is appropriately adjusted according to the white water foam situation); a neutral sizing agent AKD is added to the inlet of the pulping pump, with a weight ratio of 1.5%; a retention agent polymin is added to the outlet pipe of the pressure screen. sk, weight ratio 0.03%; main parameters of paper machine: wire speed 210m / min, width 1880mm, headbox lip opening 9.8mm, first press line pressure of press section: 500kN / m, second press line pressure: 550kN / m; curling tension: 280kN / m; the drying section has two parts, front and rear dryer, with sizing machine (film transfer surface sizing machine) in the middle, sizing machine: the part where fluorine-free oil-proofing agent is added, and a unique and innovative formula of fluorine-free oil-proofing agent coating is used for coating; its formula (Amount per ton of paper: 20kg polyether-modified organic polysilazane + 10kg surface sizing agent (CS-3), wherein the polyether-modified organic polysilazane is self-synthesized, and the surface sizing agent (CS-3) is provided by Zhejiang Chuanhua Huayang Chemical Co., Ltd.), sizing concentration 9.8%; temperature 61°C, front coating metering rod model: 21#, metering rod pressure 100kpa; back coating metering rod model: 21#, metering rod pressure 100kpa; coating single side controlled at 0.4g / m 2 Around, the paper tension before the sizing machine is 180N / m 2 , paper tension after sizing machine 160N / m 2; Actual surface sizing amount: 0.4g / m2 on the front side and 0.4g / m2 on the back side; Paper dryness of the paper entering the film transfer sizing machine ≥95%; Paper dryness of the paper exiting the film transfer sizing machine ≥75%; Through the above production process and steps, within the process and quality requirements of this application, after adjusting and drying the paper machine, fluorine-free waterproof and oil-proof paper that meets the expected quality goals can be prepared: the basis weight is 50±1g / m2 2 , moisture content is 6.0%, longitudinal tear length is 7.8Km, water absorption is 12.5g / m 2 , hue is natural white, whiteness is 84% ​​without fluorescence, front side smoothness is 45s, back side smoothness is 61s, oil proof grade is 3 (kit method to detect oil proof grade), and it also has good hot water resistance (95℃ hot water titration test). The paper samples were sent to a third-party testing agency for testing and the feedback was that no fluorine element was detected. So far, a 50g level 3 fluorine-free waterproof and oil-proof paper has been developed.

[0036] Example 2: 5-grade fluorine-free water-proof and oil-proof paper

[0037] A method for preparing fluorine-free waterproof and oil-proof paper comprises the following steps:

[0038] The pulp is a mixture of 55% bleached kraft softwood pulp and 45% bleached kraft hardwood pulp. After the pulp is evenly mixed, three double-disc mills are used for cyclic beating, with a beating degree of about 58°SR and a wet weight of about 3.9g. The amounts of auxiliary materials to the absolute dry pulp are as follows: cationic starch CS-8 is added to the inlet pipe of the pulp preparation tank, with a weight ratio of 1.0%; a small amount of defoamer stock solution is added to the white water tank of the wire, with a weight ratio of 0.012% (the amount added is appropriately adjusted according to the white water foam situation); a neutral sizing agent AKD is added to the inlet of the pulping pump, with a weight ratio of 1.5%; a retention agent polymin is added to the outlet pipe of the pressure screen. sk, weight ratio 0.03%; main parameters of paper machine: wire speed 210m / min, width 1880mm, headbox lip opening 9.8mm, first press line pressure of press section: 500kN / m, second press line pressure: 550kN / m; curling tension: 280kN / m; two parts of the drying section, front and rear dryer, with sizing machine (film transfer surface sizing machine) in the middle, sizing machine: for the addition of fluorine-free oil-proofing agent, it adopts a unique and innovative formula of fluorine-free oil-proofing agent coating for coating; its formula (ton of paper Dosage: 30kg polyether-modified organic polysilazane + 10kg surface sizing agent (CS-3), wherein the polyether-modified organic polysilazane is self-synthesized, and the surface sizing agent (CS-3) is provided by Zhejiang Chuanhua Huayang Chemical Co., Ltd.), sizing concentration 10.2%; temperature 62°C, front coating metering rod model: 21#, metering rod pressure 100kpa; back coating metering rod model: 21#, metering rod pressure 100kpa; coating single side control at 0.6-0.7g / m 2 , paper tension before sizing machine 180N / m2 , paper tension after sizing machine 160N / m 2 ; Actual surface sizing coating amount: 0.73g / m2 on the front side and 0.74g / m2 on the back side; Paper dryness of the paper entering the film transfer sizing machine ≥95%; Paper dryness of the paper exiting the film transfer sizing machine ≥75%; Through the above production process and steps, within the process and quality requirements of this application, after adjusting and drying the paper machine, fluorine-free waterproof and oil-proof paper that meets the expected quality goals can be prepared: the basis weight is 40±1g / m2 2 , moisture content is 5.8%, longitudinal tear length is 8.3Km, water absorption is 11.9g / m 2 , hue is natural white, whiteness is 84% ​​without fluorescence, front side smoothness is 46s, back side smoothness is 58s, oil proof grade is 5 (kit method to detect oil proof grade), and it also has good hot water resistance (95℃ hot water titration test). The paper samples were sent to a third-party testing agency for testing and the feedback was that no fluorine elements were detected. So far, a 40g grade 5 fluorine-free waterproof and oil-proof paper has been developed.

[0039] Example 3: 7-grade fluorine-free water-proof and oil-proof paper

[0040] A method for preparing fluorine-free waterproof and oil-proof paper comprises the following steps:

[0041] The pulp is a mixture of 55% bleached kraft softwood pulp and 45% bleached kraft hardwood pulp. After the pulp is evenly mixed, three double-disc mills are used for cyclic beating, with a beating degree of about 58°SR and a wet weight of about 3.9g. The amounts of auxiliary materials to the absolute dry pulp are as follows: cationic starch CS-8 is added to the inlet pipe of the pulp preparation tank, with a weight ratio of 1.0%; a small amount of defoamer stock solution is added to the white water tank of the wire, with a weight ratio of 0.012% (the amount added is appropriately adjusted according to the white water foam situation); a neutral sizing agent AKD is added to the inlet of the pulping pump, with a weight ratio of 1.5%; a retention agent polymin is added to the outlet pipe of the pressure screen. sk, weight ratio 0.03%; main parameters of paper machine: wire speed 210m / min, width 1880mm, headbox lip opening 9.8mm, first press line pressure of press section: 500kN / m, second press line pressure: 550kN / m; curling tension: 280kN / m; two parts of the drying section, front and rear dryer, with sizing machine (film transfer surface sizing machine) in the middle, sizing machine: for the addition of fluorine-free oil-proofing agent, it adopts a unique and innovative formula of fluorine-free oil-proofing agent coating for coating; its formula (ton of paper Dosage: 45kg polyether-modified organic polysilazane + 10kg surface sizing agent (CS-3), wherein the polyether-modified organic polysilazane is self-synthesized, and the surface sizing agent (CS-3) is provided by Zhejiang Chuanhua Huayang Chemical Co., Ltd.), sizing concentration 10.2%; temperature 62°C, front coating metering rod model: 21#, metering rod pressure 100kpa; back coating metering rod model: 21#, metering rod pressure 100kpa; coating single side control at 0.8-0.9g / m 2 , paper tension before sizing machine 180N / m 2 , paper tension after sizing machine 160N / m 2 ; Actual surface sizing coating amount: 0.88g / m2 on the front side and 0.87g / m2 on the back side; Paper dryness of the paper entering the film transfer sizing machine ≥95%; Paper dryness of the paper exiting the film transfer sizing machine ≥75%; Through the above production process and steps, within the process and quality requirements of this application, after adjusting and drying the paper machine, fluorine-free waterproof and oil-proof paper that meets the expected quality goals can be prepared: the basis weight is 40±1g / m2 2 , moisture content is 5.7%, longitudinal tear length is 8.5Km, water absorption is 11.2g / m 2 , hue is natural white, whiteness is 84% ​​without fluorescence, front side smoothness is 47s, back side smoothness is 57s, oil proof grade is 7 (kit method to detect oil proof grade), and it also has good hot water resistance (95℃ hot water titration test). The paper samples were sent to a third-party testing agency for testing and the feedback was that no fluorine elements were detected. So far, a 40g 7-grade fluorine-free waterproof and oil-proof paper has been developed.

[0042] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing fluorine-free waterproof and oil-proof paper, characterized in that: The following steps are involved: S1 pulp: bleached kraft softwood pulp 40-60%, bleached kraft hardwood pulp 40-60%; S2 beating: After the slurry is evenly mixed according to the ratio requirements, three double-disc mills are used in series for cyclic beating; S3 auxiliary materials: (a) add cationic starch to the inlet pipe of the pulp preparation tank, with a weight ratio of 1.0-1.5%; (b) add a small amount of defoamer stock solution to the white water tank of the wire; (c) add neutral sizing agent to the inlet of the pulp pump, with a weight ratio of 1.0-1.5%; (d) add retention agent to the outlet pipe of the pressure screen, with a weight ratio of 0.02-0.04%; S4 paper machine: control the main parameters of the paper machine; S5 drying: It is divided into the front drying section and the rear drying section, with the sizing machine in the middle of the front drying section and the rear drying section; S6 film transfer sizing machine: Add fluorine-free oil-proof coating and use double-sided coating, the front coating metering rod model: 21#, metering rod pressure 100kpa; the back coating metering rod model: 21#, metering rod pressure 100kpa; the coating single side is controlled at 0.3~1.0g / m 2 , the paper tension in front of the sizing machine is 180N / m 2 , the tension of the paper sheet after the sizing machine is 160N / m 2 , to form a dense waterproof and oil-proof coating on the surface of the paper; The S7 calender uses a double-nip soft calender for calendering; S8 obtains the fluorine-free waterproof and oil-proof paper after winding, rewinding, packaging and storage.

2. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: In step S2, the beating degree is 57±2°SR, and the wet weight is 3.5-4.5 g.

3. The method for preparing a fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: In step S3, the cationic starch is CS-8 cationic starch, the neutral sizing agent is AKD neutral sizing agent, and the retention aid is polymin sk retention aid.

4. The method for preparing a fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: The main parameters of the paper machine in step S4 are: wire speed 200-220 m / min, width 1880 mm, headbox lip opening 9.8 mm, first press line pressure of the press section: 500 kN / m, second press line pressure: 550 kN / m; curling tension: 280 kN / m.

5. The method for preparing a fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: In step S6, the sizing agent concentration is 10±0.5%, the temperature is 60±5°C; the surface sizing agent coating amount is ≥0.3g / m 2 , reverse side ≥ 0.3g / m 2 .

6. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 5, characterized in that: In step S6, the fluorine-free oil-proof coating is composed of a mixture of polyether-modified organic polysilazane and surface sizing agent CS-3, and the usage is 15-45 kg of polyether-modified organic polysilazane and 10 kg of surface sizing agent CS-3 per ton of paper.

7. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 6, characterized in that: The preparation method of the polyether-modified organic polysilazane is as follows: under an argon or dry air atmosphere, a Karl Fischer catalyst is added into a three-necked flask containing allyl groups, polysilazane is added after stirring, and the polyether-modified organic polysilazane is reacted to obtain the polyether-modified organic polysilazane.

8. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 7, characterized in that: The preparation method and conditions of the polyether-modified organic polysilazane are as follows: in the presence of a Carr catalyst, the allyl-PEO molecule is grafted onto the polysilazane chain through a hydrogenation reaction between the Si-H group of the polysilazane and the terminal C=C group bond of the polysilazane; the most favorable conditions for the addition of the allyl-PEO chain onto the polysilazane are: in an argon atmosphere, at 80° C., the molar ratio of the Carr catalyst to the allyl group is 3×10 -3 .

9. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: In step S6, the dryness of the finished paper entering the film transfer sizing machine is ≥95%; the dryness of the finished paper exiting the film transfer sizing machine is ≥75%.

10. The method for preparing fluorine-free waterproof and oil-proof paper according to claim 1, characterized in that: In step S7, the first pressing pressure is 50 kN / m, the second pressing pressure is 60 kN / m, the front surface smoothness is 40 to 50S, and the back surface smoothness is 50 to 70S.

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