Waterproof and oil-proof coated paper as well as preparation method and application thereof

Abstract

The invention discloses waterproof and oilproof coated paper as well as a preparation method and application thereof. The preparation method of the waterproof and oilproof paper comprises the following steps: S1, defibering a bleached bamboo pulp board, scattering, performing vacuum drying, adding analytically pure sodium hydroxide for activation, adding into analytically pure acetic anhydride, analytically pure concentrated sulfuric acid and analytically pure glacial acetic acid, and performing freeze drying to obtain cellulose diacetate; s2, preparing polyvinyl alcohol powder into a solution, coating paper with the solution, and drying; and S3, adding analytically pure dichloromethane into the cellulose diacetate solution obtained in the step S1, and coating the cellulose diacetate solution onto the coated paper obtained in the step S2 to finally obtain the waterproof and oilproof coated paper. According to the waterproof and oilproof paper prepared by the preparation method disclosed by the invention, the waterproof performance of the paper is greatly improved, so that the paper has excellent oilproof performance, high tearing strength, high bursting strength, green degradability, simple preparation process and low production cost, and is suitable for large-scale industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of functional paper, and in particular relates to a preparation method of waterproof and oil-proof coated paper and application thereof. Background Art

[0002] In the context of "paper replacing plastic", improving the functional application of paper-based materials is an inevitable development trend. However, paper-based materials composed of fibers are easily penetrated by water / oil, which reduces the mechanical strength of paper and affects the use effect. The main research direction at present is to reduce the surface energy of paper-based materials by coating with waterproof and oil-proof barrier coating to achieve barrier effect.

[0003] Research progress shows that although fluorine-based waterproof and oil-proof agents have excellent performance, they have a great impact on the biological environment. Silicon-based waterproof and oil-proof agents have excellent waterproof properties, but they need to be used in combination with oil-proof agents, which is prone to system incompatibility problems, and nano non-metallic particles are easy to agglomerate and difficult to disperse evenly, resulting in coating difficulties and other problems. In the current green and sustainable development environment, biomass-based polymers will inevitably become a research hotspot, but biomass-based polymers also have a series of disadvantages such as high cost and lack of outstanding performance advantages, which affect production and preparation. Therefore, improving the waterproof and oil-proof barrier properties of paper-based packaging materials is of great significance to further expand the application scope of paper-based materials. Coating a layer of polymer coating on the surface of paper is one of the simplest and most effective ways to improve the waterproof and oil-proof barrier properties of the paper surface, but the current single coating has poor waterproof and oil-proof performance and is difficult to meet the waterproof and oil-proof requirements of paper-based packaging materials. Therefore, the development of environmentally friendly waterproof and oil-proof paper-based barrier materials has become an urgent problem to be solved in the paper packaging industry. Summary of the invention

[0004] The purpose of the present invention is to provide a novel method for preparing waterproof and oil-proof paper in view of the above-mentioned deficiencies of the prior art. The method is simple to operate, low in cost and high in efficiency; the coating material is degradable, green and pollution-free, and the waterproof and oil-proof paper produced has improved waterproof and oil-proof properties and mechanical properties to varying degrees.

[0005] A method for preparing waterproof and oil-proof paper of the present invention comprises the following steps:

[0006] S1, disintegrating, breaking up and vacuum drying the bleached bamboo pulp board, adding analytically pure sodium hydroxide for activation, adding analytically pure acetic anhydride, analytically pure concentrated sulfuric acid and analytically pure glacial acetic acid, and freeze-drying to obtain cellulose diacetate;

[0007] S2, preparing a certain amount of polyvinyl alcohol powder into a solution, applying it onto paper, and drying it;

[0008] S3, adding analytically pure dichloromethane to the cellulose diacetate solution obtained in step S1, and applying the solution to the coated paper obtained in step S2 by dip coating, thereby finally obtaining waterproof and oil-proof coated paper.

[0009] Furthermore, in step S1, the bleached bamboo pulp board is soaked in water for 6-8 hours and spun at 10000-15000 revolutions; and vacuum drying is set at 50° C.-70° C. for 6-8 hours.

[0010] Furthermore, in step S1, the solid-liquid ratio of the bamboo pulp fiber, analytically pure acetic anhydride, analytically pure concentrated sulfuric acid, and analytically pure glacial acetic acid is 1:2:0.1:10.

[0011] Furthermore, in step S1, the reaction conditions are heating in a water bath at a temperature of 45-55° C. and heating in a water bath for 2.5-3 hours.

[0012] Further, in step S1, deionized water is added to the substance obtained in claim 4 and centrifuged at 1500-2000 rpm in a centrifuge. The supernatant is poured out and deionized water is added again until the supernatant is neutral, and the precipitated solid is taken out and freeze-dried for 36-48 hours.

[0013] Furthermore, in step S2, polyvinyl alcohol is added to water at 90°C, the ratio of water to polyvinyl alcohol is 100:6-8, a polyvinyl alcohol solution with a solution concentration of 6%-8% is prepared, applied to paper, dried in a fume hood for 60 minutes, and then placed in an oven at 60°C for drying for 120 minutes to 150 minutes.

[0014] Furthermore, in step S3, an analytically pure dichloromethane solution is used, and the ratio of dichloromethane to cellulose acetate is 100:2-6, so as to obtain a 2%-6% cellulose acetate solution, which is coated on the paper obtained in requirement 6 by dipping method, and dried in a fume hood for 60 minutes.

[0015] A waterproof and oil-proof paper prepared by the above preparation method.

[0016] The role of the waterproof and oil-proof paper prepared by the above-mentioned preparation method in the field of food packaging.

[0017] The present invention adopts an impregnation method to prepare waterproof and oil-proof paper. Compared with other coating methods, the process is simple to operate, has low energy consumption, can be widely promoted, and avoids the waste of raw materials. It can be suitable for industrial production, has a wide application prospect, and has good social and economic benefits.

[0018] The waterproof and oil-proof coating of cellulose acetate and polyvinyl alcohol has good adhesion to the surface of paper, forms a film on the surface of paper and fills the pores between fibers, improving the surface and internal conditions of the paper to varying degrees, and improving the waterproof and oil-proof properties and mechanical properties of the paper to varying degrees. It is waterproof and oil-proof and tear-resistant, high temperature resistant, highly safe for the human body, green and environmentally friendly, and highly recyclable.

[0019] The present invention proposes for the first time to use bleached bamboo pulp board to prepare cellulose acetate waterproof coating, and the raw material has the advantages of wide source and low cost. At present, the method for preparing cellulose acetate generally extracts cellulose from raw materials or prepares it with dissolving pulp. Compared with the method, the present invention can further promote the development and utilization of bamboo resources and promote the development of low-carbon economy. The prepared product has excellent waterproof and oil-proof performance, is biodegradable and environmentally friendly.

[0020] The invention uses polyvinyl alcohol and cellulose acetate as main raw materials, both of which are natural bio-based polymers. The prepared oil-proof and waterproof material is completely biodegradable and harmless to the environment and human body.

[0021] The novel waterproof and oil-proof paper prepared by the present invention has good biocompatibility, green degradability, and excellent mechanical properties, and can be applied in the fields of food packaging, express packaging, and ground film, and has very broad application prospects.

[0022] The waterproof and oil-proof paper of the present invention has an oil-proof grade of 8 or above, and Cobb60 reaches 14.88 g / m 2 Below, the water contact angle reaches above 99.9°, the tear strength can reach above 151mN, and the burst strength can reach 144.36Kpa. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0024] Figure 1 This is a SEM test image of the base paper used in the present invention;

[0025] Figure 2 This is a SEM test image of Example 1 of the present invention;

[0026] Figure 3 This is a cross-sectional scanning electron microscope (SEM) test image of Example 1 of the present invention.

[0027] The present invention has no special restrictions on the type and source of the cellulose raw materials used. The following takes chemical mechanical pulp as an example; the base paper is a hand-made sheet made in the laboratory, with an oil-proof grade of 0 and a Cobb60 of 100g / m 2, water contact angle is 10°, tear strength is 83mN, and burst strength is 60.59Kpa. DETAILED DESCRIPTION

[0028] Oil resistance test: TAPPIT 559cm-02 "Grease resistance test for paper and paperboard".

[0029] Waterproof performance: The water contact angle (WCA) of the coated paper-based material surface was measured using a Theta Flex optical contact angle meter (water drop angle meter).

[0030] Cobb60 value (g / m 2 ) Evaluate the waterproofness of paper before and after coating according to GB / T10739 standard.

[0031] Physical properties: GB / T 454-2020 Determination of bursting strength of paper, GB / T 455-2002 Determination of tear resistance of paper and paperboard.

[0032] Example 1

[0033] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0034] The hand-made sheets made of chemical mechanical pulp were soaked in 8% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 20 g / m 2 Recorded as sample 1, sample 1 was immersed in 5% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 10g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0035] Example 2

[0036] The difference from Example 1 is that:

[0037] The 4% polyvinyl alcohol in implementation 1 was changed to 3% while the other processes remained unchanged.

[0038] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0039] The hand-made sheets made of chemical mechanical pulp were soaked in 7% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 15g / m 2Recorded as sample 1, sample 1 was immersed in 5% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 10g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0040] Example 3

[0041] The difference from Example 1 is that:

[0042] The 4% polyvinyl alcohol in implementation 1 was changed to 2% while the other processes remained unchanged.

[0043] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0044] The hand-made sheets made of chemical mechanical pulp were soaked in 6% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 10 g / m 2 Recorded as sample 1, sample 1 was immersed in 5% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 10g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0045] Example 4

[0046] The difference from Example 1 is that:

[0047] The 5% cellulose acetate in Example 1 was changed to 4% while other processes remained unchanged.

[0048] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0049] The hand-made sheets made of chemical mechanical pulp were soaked in 8% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 20 g / m 2 Recorded as sample 1, sample 1 was immersed in 4% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 8g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0050] Example 5

[0051] The difference from Example 1 is that:

[0052] The 5% cellulose acetate in implementation 1 was changed to 3% while the other processes remained unchanged.

[0053] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0054] The hand-made sheets made of chemical mechanical pulp were soaked in 8% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 20 g / m 2 Recorded as sample 1, sample 1 was immersed in 3% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 6g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0055] Example 6

[0056] The difference from Example 1 is that:

[0057] The 5% cellulose acetate in implementation 1 was changed to 6% while the other processes remained unchanged.

[0058] The method for preparing the waterproof and oil-proof paper of this embodiment comprises:

[0059] The hand-made sheets made of chemical mechanical pulp were soaked in 8% polyvinyl alcohol solution for 10 seconds, placed flat on a glass sheet in a fume hood for 1 hour, and then placed in a 60℃ oven for 1 hour. The coating amount was calculated to be 20 g / m 2 Recorded as sample 1, sample 1 was immersed in 6% cellulose acetate solution for 2 minutes and the coating amount was calculated to be 12g / m 2 , take it out and place it in a fume hood for 1 hour, record it as sample 2, dry sample 2 in a flat dryer at 70°C, and then calender it in a calender at 50KN / cm and 70°C to finally obtain waterproof and oil-proof paper.

[0060] like Figure 2 As shown in the scanning electron microscope image of the waterproof and oil-proof paper prepared in Example 1 of the present invention, polyvinyl alcohol and cellulose acetate form a dense film on the surface of the paper, thereby improving the oil-proof effect of the paper, and polyvinyl alcohol and cellulose acetate fill the pores between the paper fibers, thereby improving the physical properties and waterproof properties of the paper. Figure 3 The figure shows a cross-section of the waterproof and oil-proof paper prepared in Example 1 of the present invention through a scanning electron microscope, which further illustrates that polyvinyl alcohol and cellulose acetate form a waterproof and oil-proof film on the surface of the paper.

[0061] Table 1 Performance indexes of waterproof and oil-proof packaging paper

[0062]

[0063] It can be seen from Table 1 that when the polyvinyl alcohol solution reaches 6%, the coating amount of the paper oil-proof layer reaches 20g / m 2 When the oil-proof grade reaches level 12. Comparative Examples 1, 2, and 3, as the concentration of polyvinyl alcohol decreases, the quality of the polyvinyl alcohol film formed on the surface decreases, resulting in a downward trend in the coating amount, contact angle, tear strength, and burst strength, and an upward trend in the Viscosity value, indicating a decrease in the water-blocking effect. Comparative Examples 1, 4, 5, and 6, as the concentration of cellulose acetate solution decreases, cellulose acetate is not well dispersed on the paper surface, resulting in a downward trend in the coating amount, contact angle, tear strength, and burst strength, and an upward trend in the Viscosity value.

[0064] In summary, the waterproof and oil-proof packaging paper coating of the present invention is tightly combined with paper fibers, has high oil resistance grade, high tear strength, high bursting strength, low viscosity value, large contact angle, and good water resistance.

[0065] For matters not mentioned above, the prior art applies.

[0066] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing waterproof and oil-proof paper, characterized in that: The following steps are involved: S1, disintegrating, breaking up and vacuum drying the bleached bamboo pulp board, adding analytically pure sodium hydroxide for activation, adding analytically pure acetic anhydride, analytically pure concentrated sulfuric acid and analytically pure glacial acetic acid, and freeze-drying to obtain cellulose diacetate; S2, preparing a certain amount of polyvinyl alcohol powder into a solution, applying it onto paper, and drying it; S3, adding analytically pure dichloromethane to the cellulose diacetate solution obtained in step S1, and applying the solution to the coated paper obtained in step S2 by dipping method, so as to finally obtain waterproof and oil-proof coated paper.

2. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In the step S1, the bleached bamboo pulp board is soaked in water for 6-8 hours and debonded at 10000-15000 revolutions; and vacuum dried at 50° C.-70° C. for 6-8 hours.

3. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In the step S1, the solid-liquid ratio of the bamboo pulp fiber, analytically pure acetic anhydride, analytically pure concentrated sulfuric acid, and analytically pure glacial acetic acid is 1:2:0.1:

10.

4. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In the step S1, the reaction conditions are as follows: heating the reaction in a water bath at a temperature of 45-55° C. for 2.5-3 hours.

5. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In step S1, deionized water is added to the substance obtained in claim 4 and centrifuged at 1500-2000 rpm in a centrifuge. The supernatant is poured out and deionized water is added again until the supernatant becomes neutral, and the precipitated solid is taken and freeze-dried for 36-48 hours.

6. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In the step S2, polyvinyl alcohol is added to water at 90° C., the ratio of water to polyvinyl alcohol is 100:6-8, a polyvinyl alcohol solution with a concentration of 6%-8% is prepared, and the solution is coated on the paper by dipping method, dried in a fume hood for 60 minutes, and then placed in an oven at 60° C. to dry for 120-150 minutes.

7. The method for preparing a waterproof and oil-proof paper according to claim 1, characterized in that: In step S3, analytically pure dichloromethane solution is used, and the ratio of dichloromethane to cellulose acetate is 100:2-6, to prepare a 2%-6% cellulose acetate solution, which is applied to the paper obtained in requirement 6, and dried in a fume hood for 60 minutes. Calendering is performed under the conditions of 60°C and 50KN / cm.

8. A waterproof and oil-proof paper prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the waterproof and oil-proof paper as claimed in claim 8 in the field of food packaging.

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