A method for preparing a water and oil repellent paper base material having a composite coating

Abstract

The application discloses a preparation method of waterproof and oil-proof paper base material containing a composite coating and belongs to the technical field of packaging paper, and comprises the following steps: S1, preparing a sodium alginate aqueous solution to obtain coating A; S2, preparing a PLA and PBAT mixed solution to obtain coating B; S3, uniformly coating the coating A on the surface of kraft paper base paper, and then performing drying and hot pressing to obtain dried kraft paper base paper with a smooth surface; and S4, uniformly coating the coating B on the surface of the kraft paper base paper coated with the coating A, and fully drying to obtain the waterproof and oil-proof paper base material containing a sodium alginate, PLA and PBAT composite coating. The waterproof and oil-proof paper base material prepared by the method has significantly improved waterproof and oil-proof performance of paper and retains the biodegradable characteristics, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of packaging paper, and particularly relates to a preparation method of waterproof and oil-proof paper base material containing a composite coating. BACKGROUND

[0002] Waterproof and oil-proof paper is a kind of paper base material with special functions, which has good barrier properties to both water and oil, and is widely used in packaging, protection and other fields. Paper and paperboard, as two basic materials in the packaging field, are widely used in the packaging of various products due to their strong plasticity, low cost and easy processing. However, the inherent porous structure of these two types of materials and the hydrophilic properties of fibers make them have obvious deficiencies in waterproofness and oil resistance. To some extent, this deficiency limits their application in certain packaging requirements, especially in applications that require moisture and oil resistance.

[0003] In order to endow paper materials with waterproof and oil-proof properties, it is usually necessary to treat or add specific additives to paper materials to enhance their waterproof and oil-proof performance. Currently, there are two methods for waterproof and oil-proof treatment of paper materials. The first method is to cover a waterproof and oil-proof plastic layer on the surface of the paper (commonly known as film coating or plastic coating). Although this method can effectively improve the waterproof and oil-proof ability of the paper, it only reduces the degree of plastic pollution and does not fundamentally solve the problem of plastic pollution. In contrast, the second method is to coat a waterproof and oil-proof coating on the surface of the paper to achieve the effect of waterproof and oil-proof. This method not only endows the paper with good waterproof and oil-proof performance, but also maximizes the biodegradability and environmental advantages of recycling of the paper.

[0004] However, the waterproof and oil-proof performance of the current single coating is poor, which is difficult to meet the waterproof and oil-proof requirements of paper base packaging materials. Therefore, the development of environmentally friendly waterproof and oil-proof paper base barrier materials has become a problem that needs to be solved in the paper packaging industry. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a preparation method of waterproof and oil-proof paper base material containing a composite coating, which can obtain paper base material with high waterproof and oil-proof performance, effectively prolong the service life of the packaged goods, and at the same time maintain the environmental characteristics of the material, meeting the market demand for high-performance and environmentally friendly packaging materials.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A preparation method of waterproof and oil-proof paper base material containing a composite coating, comprising the following operation steps:

[0008] S1, preparing a sodium alginate aqueous solution to obtain coating A;

[0009] S2, a PLA and PBAT mixed solution is prepared to obtain coating B;

[0010] S3, coating A is uniformly coated on the surface of the kraft paper base paper, and then drying and hot pressing are performed to obtain dried kraft paper base paper with a smooth surface;

[0011] S4, coating B is uniformly coated on the surface of the kraft paper base paper coated with coating A, and then sufficient drying is performed to obtain a waterproof and oil-proof paper base material containing a sodium alginate, PLA and PBAT composite coating.

[0012] Preferably, in step S1, the mass-volume percentage concentration of the sodium alginate aqueous solution is 1% to 4%.

[0013] Preferably, the preparation method of the sodium alginate aqueous solution is as follows: a beaker is filled with weighed deionized water, and placed in a 45℃ water bath, a certain mass of sodium alginate is poured into the beaker under magnetic stirring, and stirred for 1h to obtain a sodium alginate solution with a mass-volume percentage concentration of 1% to 4%.

[0014] Preferably, in step S2, the mass-volume percentage concentration of the PLA and PBAT mixed solution is 5% to 15%.

[0015] Preferably, the preparation method of the PLA and PBAT mixed solution is as follows: PLA and PBAT particles are weighed according to a certain ratio, poured into a reagent bottle, a solvent is added, and oscillation is performed in a 45℃ water bath for 4h to make them fully dissolved, and then standing is performed to eliminate air bubbles, to obtain a PLA and PBAT mixed solution with a mass-volume percentage concentration of 5% to 15%.

[0016] Preferably, the mass ratio of the weighed PLA and PBAT is 5:1-10.

[0017] Preferably, the solvent is one of dichloromethane and trichloromethane.

[0018] Preferably, in step S3, the kraft paper base paper coated with coating A is dried in an oven at 105℃ for 2min, and then hot pressed at a temperature of 105℃ and a pressure of about 0.2kPa for 1min to obtain dried kraft paper base paper with a smooth surface.

[0019] Preferably, in step S3, the coating amount of coating A is controlled to be 1-4g / m 2 ; in step S4, the coating amount of coating B is controlled to be 3-10g / m 2 ; and the total coating amount is controlled to be 1-13g / m 2 .

[0020] By adopting the above technology, the application has the following beneficial effects:

[0021] 1.The application uses sodium alginate, PLA and PBAT as oil-resistant functional components, and a coating with strong water and oil resistance is prepared by mutual compounding of the three components, and the coating can greatly improve the water and oil resistance of the coated paper and improve the application value of the paper.

[0022] 2.Sodium alginate is a natural polysaccharide and can be extracted from seaweed. PLA and PBAT are both new biodegradable materials, and PBAT can greatly improve the toughness of PLA. Coating the three raw materials on paper can improve the water and oil resistance of the paper while retaining its biodegradable properties. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0024] Figure 1 A flowchart of a preparation method of a water and oil resistant paper base material with a composite coating provided by the embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. It should be pointed out that the following detailed description is exemplary and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0026] The kraft paper base paper used in the embodiment is sourced from Guangzhou Paper Group Co., Ltd., with a basis weight of 70g / m 2 and an A4 paper size. The kraft paper base paper has an oil resistance level of 0 level, and a cobb 60 value of 82.8g / m 2 .

[0027] Embodiment 1

[0028] 1. Weigh 98.5g of distilled water into a beaker, and place the beaker in a 45℃ water bath with magnetic stirring. Weigh 1.5g of sodium alginate and slowly pour it into the beaker. After completely pouring, seal the mouth of the beaker, stir in the water bath for 1h, take out and stand.

[0029] 2. According to the ratio of 5:1, weigh 5g of PLA and PBAT in total and pour them into a wide-mouth bottle. Add 45g of chloroform to the bottle, cover the bottle cap, and place it in a 45℃ water bath for oscillation for 4h. After standing, it is ready for use.

[0030] (4) The sodium alginate solution was uniformly coated on the surface of the kraft paper base paper, dried in an oven at 105°C for 2 min, and then hot-pressed at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min to dry the coated paper and make the surface flat. The coating amount was about 1.5 g / m 2 .

[0031] (5) The PLA and PBAT mixed solution was uniformly coated on the surface of the coated kraft paper obtained in step (4), and the coated paper was placed in a fume hood for sufficient drying, thereby obtaining a waterproof and oil-proof paper base material containing a composite coating of sodium alginate, PLA and PBAT. The total coating amount was about 7.5 g / m 2 .

[0032] Results: The obtained waterproof and oil-proof paper had an oil-proof grade of 12, and the cobb 60 was 0.84 g / m 2 .

[0033] Example 2

[0034] (1) 98.5 g of distilled water was weighed into a beaker, and the beaker was placed in a water bath at 45°C and magnetically stirred. 1.5 g of sodium alginate was slowly poured into the beaker. After completely pouring, the mouth of the beaker was covered, and stirring was carried out in the water bath for 1 h, and then the beaker was taken out and allowed to stand.

[0035] (2) According to a ratio of 5:2, 5 g of PLA and PBAT with a total weight was weighed into a wide-mouth bottle, 45 g of chloroform was added to the bottle, the bottle was covered with a cap, and the bottle was placed in a water bath at 45°C and shaken for 4 h. After standing, the mixture was ready for use.

[0036] (3) The sodium alginate solution was uniformly coated on the surface of the kraft paper base paper, dried in an oven at 105°C for 2 min, and then hot-pressed at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min to dry the coated paper and make the surface flat. The coating amount was about 1.5 g / m 2 .

[0037] (4) The PLA and PBAT mixed solution was uniformly coated on the surface of the coated kraft paper obtained in step (3), and the coated paper was placed in a fume hood for sufficient drying, thereby obtaining a waterproof and oil-proof paper base material containing a composite coating of sodium alginate, PLA and PBAT. The total coating amount was about 7.5 g / m 2 .

[0038] Results: The obtained waterproof and oil-proof paper had an oil-proof grade of 12, and the cobb 60 was 0.91 g / m 2 .

[0039] Example 3

[0040] 1. Weigh 98.5 g of distilled water into a beaker, and place the beaker in a water bath at 45°C and stir magnetically. Weigh 1.5 g of sodium alginate and slowly pour it into the beaker. After pouring completely, seal the mouth of the beaker, and stir in the water bath for 1 h, take out, and stand.

[0041] 2. Weigh PLA and PBAT with a total weight of 5 g in a ratio of 5:3 into a jar, add 45 g of chloroform to the jar, cover the jar with a lid, and place it in a water bath at 45°C and shake for 4 h, take out, stand, and reserve.

[0042] 3. Uniformly coat the sodium alginate solution on the surface of the kraft paper base paper, dry it in an oven at 105°C for 2 min, and then heat press it at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min to dry the coated paper and make the surface flat. The coating amount is about 1.5 g / m 2 .

[0043] 4. Uniformly coat the mixed solution of PLA and PBAT on the surface of the coated kraft paper obtained in step 3, and dry the coated paper in a fume hood to obtain a waterproof and oil-proof paper base material containing a composite coating of sodium alginate, PLA, and PBAT. The total coating amount is about 7.5 g / m 2 .

[0044] Results: The obtained waterproof and oil-proof paper has an oil-proof grade of 12, and a cobb 60 of 0.89 g / m 2 .

[0045] Example 4

[0046] 1. Weigh 98.5 g of distilled water into a beaker, and place the beaker in a water bath at 45°C and stir magnetically. Weigh 1.5 g of sodium alginate and slowly pour it into the beaker. After pouring completely, seal the mouth of the beaker, and stir in the water bath for 1 h, take out, and stand.

[0047] 2. Weigh PLA and PBAT with a total weight of 5 g in a ratio of 5:4 into a jar, add 45 g of chloroform to the jar, cover the jar with a lid, and place it in a water bath at 45°C and shake for 4 h, take out, stand, and reserve.

[0048] 3. Uniformly coat the sodium alginate solution on the surface of the kraft paper base paper, dry it in an oven at 105°C for 2 min, and then heat press it at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min to dry the coated paper and make the surface flat. The coating amount is about 1.5 g / m 2 .

[0049] PLA and PBAT mixed solution is uniformly coated on the surface of the coated kraft paper obtained in step 6, and the coated paper is placed in a fume hood for sufficient drying, to obtain a waterproof and oil-proof paper base material containing a sodium alginate, PLA and PBAT composite coating. The total coating amount is about 7.5 g / m 2 .

[0050] Results: The obtained waterproof and oil-proof paper has an oil-proof grade of 12, and the cobb 60 is 2.19 g / m 2 .

[0051] Example 5

[0052] 1. 98.5 g of distilled water was weighed into a beaker, and the beaker was placed in a water bath at 45°C for magnetic stirring. 1.5 g of sodium alginate was slowly poured into the beaker. After completely pouring, the mouth of the beaker was sealed, and stirring was performed in the water bath for 1 h, and then the beaker was taken out and allowed to stand.

[0053] 2. PLA and PBAT with a total weight of 5 g were weighed according to a ratio of 5:5, and poured into a wide-mouth bottle. 45 g of chloroform was added to the bottle, the bottle was covered with a cap, and placed in a water bath at 45°C for shaking for 4 h. After standing, it was ready for use.

[0054] 3. The sodium alginate solution was uniformly coated on the surface of the kraft paper base paper, and dried in an oven at 105°C for 2 min. Then, the coated paper was dried and the surface was smooth by hot pressing at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min. The coating amount was about 1.5 g / m 2 .

[0055] 4. PLA and PBAT mixed solution was uniformly coated on the surface of the coated kraft paper obtained in step 3, and the coated paper was placed in a fume hood for sufficient drying, to obtain a waterproof and oil-proof paper base material containing a sodium alginate, PLA and PBAT composite coating. The total coating amount was about 7.5 g / m 2 .

[0056] Results: The obtained waterproof and oil-proof paper has an oil-proof grade of 12, and the cobb 60 is 1.64 g / m 2 .

[0057] Comparative Example 1

[0058] 1. 98.5 g of distilled water was weighed into a beaker, and the beaker was placed in a water bath at 45°C for magnetic stirring. 1.5 g of sodium alginate was slowly poured into the beaker. After completely pouring, the mouth of the beaker was sealed, and stirring was performed in the water bath for 1 h, and then the beaker was taken out and allowed to stand.

[0059] (2) The sodium alginate solution was uniformly coated on the surface of the kraft paper base paper, dried in an oven at 105°C for 2 min, and then hot-pressed at a temperature of 105°C and a pressure of about 0.2 kPa for 1 min to dry the coated paper and make the surface flat. The coating amount was about 1.5 g / m 2 .

[0060] Results: The obtained waterproof and oil-proof paper had an oil-proof grade of 3, a cobb 60 value of 78.0 g / m 2 .

[0061] Comparative Example 2

[0062] (1) PLA and PBAT with a total weight of 5 g were weighed according to a ratio of 5:1, poured into a wide-mouth bottle, 45 g of chloroform was added to the bottle, the bottle was covered with a cap, and then placed in a water bath at 45°C for oscillation for 4 h. After taking out and standing, the mixture was ready for use.

[0063] (2) The PLA and PBAT mixed solution was uniformly coated on the surface of the kraft paper, and the coated paper was dried in a fume hood to obtain a waterproof and oil-proof paper base material containing a PLA and PBAT coating layer. The coating amount was about 6 g / m 2 .

[0064] Results: The obtained waterproof and oil-proof paper had an oil-proof grade of 4, a cobb 60 value of 3.38 g / m 2 .

[0065] Through comparative analysis of the examples and comparative examples, it can be clearly seen that the present application has a significant effect on improving the waterproof and oil-proof performance of paper. In the examples, by carefully designing the preparation process, sodium alginate, PLA (polylactic acid) and PBAT (polyethylene terephthalate-co-caprolactone) are effectively compounded together to form a high-performance coating layer. The coating layer not only significantly improves the waterproof and oil-proof performance of the kraft paper base paper, but also makes the oil-proof grade reach 12, and the cobb 60 value is relatively low, indicating that it has good waterproof performance. In addition, with the change of the ratio of PLA to PBAT, the waterproof and oil-proof performance of the coating layer also shows a certain regularity, which provides a basis for further optimization of the formula.

[0066] In contrast, the paper in the comparative examples does not show such excellent performance. Comparative Example 1 only uses sodium alginate as the coating component. Although sodium alginate is a natural polysaccharide and has certain hydrophilicity and film-forming property, its waterproof and oil-proof effect is limited when used alone, resulting in an oil-proof grade of only 3 for the obtained paper, and a cobb 60 value as high as 78.0 g / m 2, the waterproof and oil-proof performance is poor. The comparative example 2 only uses a mixed solution of PLA and PBAT as the coating, although both of the materials are biodegradable, but when used alone, it also cannot achieve the expected waterproof and oil-proof effect, the oil-proof grade is only 4, and the cobb 60 value is 3.38g / m 2 .

[0067] In summary, the embodiment of the present application successfully prepares a high-performance waterproof and oil-proof paper-based material by skillfully combining sodium alginate, PLA and PBAT, which not only significantly improves the waterproof and oil-proof performance of the paper, but also retains its biodegradable properties, and has a broad application prospect.

[0068] The above describes in detail the preparation method of the waterproof and oil-proof paper-based material with a composite coating provided by the present application. The principles and implementation modes of the present application are described by applying specific examples, and the above description of the examples is only applicable to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a waterproof and oil-resistant paper-based material with a composite coating, characterized in that, The following steps are included: S1. Prepare sodium alginate aqueous solution to obtain coating A; the preparation method of sodium alginate aqueous solution is as follows: pour weighed deionized water into a beaker, place it in a 45℃ water bath, pour in a certain mass of sodium alginate under magnetic stirring, stir for 1 h, and obtain sodium alginate aqueous solution with a mass percentage concentration of 1% to 4%. S2. Prepare a mixed solution of PLA and PBAT to obtain coating B; the preparation method of the mixed solution of PLA and PBAT is as follows: weigh PLA and PBAT particles according to the mass ratio of PLA and PBAT particles of 5:1-10, pour them into a reagent bottle, add solvent, shake in a 45℃ water bath for 4 h to fully dissolve them, let stand to eliminate bubbles, and obtain a mixed solution of PLA and PBAT with a mass percentage concentration of 5% to 15%; S3. Coating A is evenly applied to the surface of the kraft paper base paper, and then dried and hot-pressed to obtain a dry and smooth kraft paper base paper. The drying step is to dry in an oven at 105℃ for 2 minutes, and the hot-pressing step is to hot-press at a temperature of 105℃ and a pressure of about 0.2kPa for 1 minute to obtain a dry and smooth kraft paper base paper. S4. Apply coating B evenly to the surface of the kraft base paper that has been coated with coating A, and dry it thoroughly to obtain a waterproof and oil-resistant paper-based material containing a composite coating of sodium alginate, PLA and PBAT. In step S3, the coating amount of paint A is controlled to be 1-4 g / m². 2 In step S4, the coating amount of paint B is controlled to be 3-10 g / m². 2 The total coating amount should be controlled at 1-13 g / m². 2 .

2. The method for preparing a waterproof and oil-resistant paper-based material with a composite coating according to claim 1, characterized in that: The solvent is one of dichloromethane and trichloromethane.

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