Environment-friendly oil-proof and water-proof packaging paper and preparation method thereof

Abstract

The invention discloses environment-friendly oil-proof and water-proof packaging paper and a preparation method thereof.The surface of body paper is coated with an oil-proof agent to form an oil-proof coating, the oil-proof coating is coated with a water-proof agent to form a water-proof coating, and the oil-proof agent comprises a chitosan solution, a sodium alginate solution, a cross-linking agent and glycerin; the waterproof agent comprises a palm oil paraffin solution and hydrophobic nano silicon dioxide. The packaging paper disclosed by the invention has excellent oil-proof and water-proof performance and can be biodegraded, so that the pollution to the environment is reduced. The invention further discloses a preparation method of the environment-friendly oil-proof and water-proof packaging paper, operation is easy, and mass production of the oil-proof and water-proof packaging paper is facilitated.

Description

Technical Field

[0001] The invention relates to the field of packaging paper, and in particular to environmentally friendly oil-proof and waterproof packaging paper and a preparation method thereof. Background Art

[0002] Wrapping paper usually uses coating, laminating and other methods to apply waterproof or oil-proof coatings on the surface of paper. For example, traditional wrapping paper usually coats petroleum-based polymers on paper to make the paper waterproof or oil-proof, but petroleum-based polymers are difficult to degrade in nature and will cause serious environmental pollution after large-scale use. In addition, incineration of such wrapping paper will also release toxic and harmful gases, causing atmospheric pollution.

[0003] In order to deal with the environmental and resource problems caused by petroleum-based polymers, people began to look for and develop alternative materials, such as bio-based polymers. These materials have the advantages of being renewable and degradable, and gradually replace petroleum-based polymers. For example, the Chinese patent with publication number CN116289330A discloses a degradable coating for food packaging paper and its preparation process, wherein the surface of the paper-based material is coated with an antioxidant layer coating liquid, a protein layer coating liquid and a hydrophobic layer coating liquid in sequence to form a degradable coating with a three-layer composite structure. Among them, the upper hydrophobic layer coating liquid is a mixture of chitosan quaternary ammonium salt grafted polylactic acid and beeswax emulsion; the protein layer coating liquid of the middle layer is a dispersion of protein powder and nano starch crystals; the lower antioxidant layer coating liquid is in direct contact with the paper-based material and is a mixture of oxidized starch, vitamin C, anthocyanin, and onion juice. The degradable coating has strong adhesion and can be stably attached to the surface of the paper-based material, effectively blocking water vapor and oxygen, and at the same time improving the tensile strength of the paper-based material, but the above-mentioned packaging paper cannot be oil-proof.

[0004] In view of this, the present invention provides an environmentally friendly oil-proof and waterproof packaging paper and a preparation method thereof to solve the above problems. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned technologies, the present invention provides an environmentally friendly oil-proof and waterproof packaging paper, which has excellent oil-proof and waterproof capabilities, is biodegradable, and is environmentally friendly.

[0006] An environmentally friendly oil-proof and waterproof packaging paper comprises base paper, wherein the surface of the base paper is coated with an oil-proof agent to form an oil-proof coating, and the oil-proof coating is formed by coating a waterproofing agent to form a waterproof coating, wherein the oil-proof agent comprises a chitosan solution, a sodium alginate solution, a cross-linking agent, and glycerol; and the waterproofing agent comprises a palm oil paraffin solution and hydrophobic nano-silica.

[0007] Preferably, the oil-proof agent comprises the following raw materials in parts by mass: 50-90 parts of chitosan solution, 10-50 parts of sodium alginate solution, 0.1-0.3 parts of cross-linking agent, and 0.5 parts of glycerol, wherein the mass fraction of chitosan in the chitosan solution is 2%, and the mass fraction of sodium alginate in the sodium alginate solution is 1.5%.

[0008] Preferably, the cross-linking agent is 4-hydroxy-3-methoxycinnamic acid.

[0009] Preferably, the solvent of the chitosan solution is ionized water, and the chitosan solution includes glacial acetic acid as a co-solvent; and the solvent of the sodium alginate solution is ionized water.

[0010] Preferably, the waterproofing agent comprises the following raw materials in parts by weight: 30 to 31 parts of palm oil paraffin solution and 0.3 to 0.6 parts of hydrophobic nano-silicon dioxide, and the mass fraction of palm oil paraffin in the palm oil paraffin solution is 1% to 3%.

[0011] Preferably, the solvent of the palm oil paraffin solution is ethanol.

[0012] Preferably, the base paper is coated with 1-5 g of oil-proofing agent per square meter.

[0013] Preferably, the base paper is coated with 1-5 g of waterproofing agent per square meter.

[0014] The present invention further provides a method for preparing environmentally friendly oil-proof and waterproof packaging paper, comprising the following steps:

[0015] Step 1: adding glacial acetic acid to deionized water to obtain a glacial acetic acid solution; then adding chitosan to the glacial acetic acid solution, stirring and heating to obtain a chitosan solution;

[0016] Step 2: adding sodium alginate into deionized water to obtain a sodium alginate solution;

[0017] Step 3: Mix the chitosan solution with the sodium alginate solution, add a cross-linking agent to react for 20 to 40 minutes, and then add glycerol to react for 20 to 40 minutes to obtain an oil-proofing agent;

[0018] Step 4: dissolving palm oil paraffin in ethanol and heating to obtain a palm oil paraffin solution; then adding hydrophobic nano-silica to the palm oil paraffin solution and stirring to obtain a waterproofing agent;

[0019] Step 5: Drying the oil-proof agent on the surface of the base paper, and drying to form an oil-proof coating on the surface of the base paper;

[0020] Step six: Apply the oil-proof agent on the surface of the oil-proof coating and dry it to obtain environmentally friendly oil-proof and waterproof packaging paper.

[0021] Preferably, in the step five, the base paper is dried for 20 minutes at 60° C. and a relative humidity of 50%; and then the base paper is placed at room temperature for 24 hours; in the step six, the base paper is dried for 30 minutes at 35° C. and a relative humidity of 50%, and then the base paper is placed at room temperature for 24 hours.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention forms a network of oleophobic composites by cross-linking sodium alginate and chitosan, and the oleophobic composites are coated on base paper to form an oil-proof coating, so that the packaging paper has excellent oil-proof performance and improves the mechanical properties of the packaging paper.

[0024] 2. The present invention also forms a waterproof coating by coating a waterproof agent on the surface of the oil-proof coating, which not only makes the packaging paper have excellent waterproof performance, but also because the chitosan cross-linked complex has a certain water solubility, the waterproof coating can also protect the oil-proof coating from contacting with external water. The waterproof coating includes palm oil paraffin and hydrophobic nano-silicon dioxide, and the formed waterproof coating is more compact and has a better waterproof effect. The hydrophobic nano-silicon dioxide not only improves the adhesion of the waterproof coating, but also makes the waterproof coating and the oil-proof coating tightly connected. The hydrophobic nano-silicon dioxide can also improve the wear resistance of the packaging paper.

[0025] 3. The oil-proof coating and the waterproof coating of the present invention are both biodegradable, reducing pollution to the environment, and are low-toxic or even non-toxic to the human body, and can be widely used in various product packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a waterproof test result diagram of Example 1, Examples 7 to 10, and Comparative Example 1 of the present invention;

[0027] Figure 2 It is a diagram of the oil-proof test results of Example 1, Examples 7 to 10, and Comparative Example 1 of the present invention;

[0028] The implementation, functional features and advantages of the present invention will be further described in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The features of the present invention and other related features are further described in detail below through embodiments to facilitate understanding by those skilled in the art:

[0030] An embodiment of the present invention provides an environmentally friendly oil-proof and waterproof packaging paper, comprising base paper, wherein the surface of the base paper is coated with an oil-proof agent to form an oil-proof coating, and the oil-proof coating is formed by coating a waterproof agent to form a waterproof coating, wherein the oil-proof agent comprises a chitosan solution, a sodium alginate solution, a cross-linking agent, and glycerol; and the waterproof agent comprises a palm oil paraffin solution and hydrophobic nano-silica.

[0031] In some embodiments, the oil-proof agent comprises the following raw materials in parts by mass: 50-90 parts of chitosan solution, 10-50 parts of sodium alginate solution, 0.1-0.3 parts of a cross-linking agent, and 0.5 parts of glycerol. The mass fraction of chitosan in the chitosan solution is 2%, and the mass fraction of sodium alginate in the sodium alginate solution is 1.5%.

[0032] In some embodiments, the cross-linking agent is 4-hydroxy-3-methoxycinnamic acid.

[0033] In some embodiments, the solvent of the chitosan solution is ionized water, and the chitosan solution includes a co-solvent, glacial acetic acid; and the solvent of the sodium alginate solution is ionized water.

[0034] In some embodiments, the waterproofing agent comprises the following raw materials in parts by weight: 30 to 31 parts of palm oil paraffin solution and 0.3 to 0.6 parts of hydrophobic nano-silica, and the mass fraction of palm oil paraffin in the palm oil paraffin solution is 1% to 3%.

[0035] In some embodiments, the solvent of the palm oil paraffin solution is ethanol, which can not only dissolve the palm oil paraffin well, but also make the palm oil paraffin evenly spread as an oil-proof coating.

[0036] In some embodiments, the base paper is coated with 1-5 g of oil-proof agent per square meter.

[0037] In some embodiments, the base paper is coated with 1-5 g of waterproofing agent per square meter.

[0038] The embodiment of the present invention also provides a method for preparing environmentally friendly oil-proof and waterproof packaging paper, comprising the following steps:

[0039] Step 1: adding glacial acetic acid to deionized water to obtain a glacial acetic acid solution; then adding chitosan to the glacial acetic acid solution, stirring and heating to obtain a chitosan solution;

[0040] Step 2: adding sodium alginate into deionized water to obtain a sodium alginate solution;

[0041] Step 3: Mix the chitosan solution with the sodium alginate solution, add a cross-linking agent to react for 20 to 40 minutes, and then add glycerol to react for 20 to 40 minutes to obtain an oil-proofing agent;

[0042] Step 4: dissolving palm oil paraffin in ethanol and heating to obtain a palm oil paraffin solution; then adding hydrophobic nano-silica to the palm oil paraffin solution and stirring to obtain a waterproofing agent;

[0043] Step 5: Drying the oil-proof agent on the surface of the base paper, and drying to form an oil-proof coating on the surface of the base paper;

[0044] Step six: Apply the oil-proof agent on the surface of the oil-proof coating and dry it to obtain environmentally friendly oil-proof and waterproof packaging paper.

[0045] In some embodiments, the glacial acetic acid solution in step 1 is added to chitosan, and the mixture is stirred and heated in a water bath at 70° C. for 1 h to obtain a chitosan solution;

[0046] In some embodiments, sodium alginate is added to the deionized water in step 2, and the mixture is stirred and heated in a water bath at 60° C. for 1 h to obtain a sodium alginate solution;

[0047] In some embodiments, after glycerol is added to the chitosan solution and the sodium alginate solution to react for 20 to 40 minutes, it is necessary to uniformly disperse the substances in the oil-proofing agent by ultrasound.

[0048] In some embodiments, palm oil paraffin is added to ethanol and heated in a water bath at 80° C. to obtain a palm oil paraffin solution.

[0049] In some embodiments, the step five comprises drying the base paper at 60° C. and 50% relative humidity for 20 minutes; and then placing the base paper at room temperature for 24 hours.

[0050] In some embodiments, the step six is ​​to dry the base paper for 30 minutes at 35° C. and 50% relative humidity, and then place the base paper at room temperature for 24 hours.

[0051] Embodiment 1 of the present invention provides an environmentally friendly oil-proof and waterproof packaging paper, and the preparation method thereof comprises the following steps:

[0052] Step 1: Add 1 g of glacial acetic acid to 97 g of deionized water, stir on a magnetic stirrer for 5 min to obtain a glacial acetic acid solution, add 2 g of chitosan to the glacial acetic acid solution, stir in a 70°C water bath for 1 h to obtain a chitosan solution with a mass fraction of 2.0%.

[0053] Step 2: Add 1.5 g of sodium alginate to 98.5 g of deionized water, stir in a 60° C. water bath for 1 h to obtain a sodium alginate solution with a mass fraction of 1.5%.

[0054] Step 3: 80 g of chitosan solution was mixed with 20 g of sodium alginate solution, 0.1 g of 4-hydroxy-3-methoxycinnamic acid was added, and the mixture was reacted for 30 min. Then glycerol was added, and the mixture was reacted for 30 min. The mixture was then ultrasonicated for 10 min to obtain an oil-proofing agent.

[0055] Step 4: Add 0.3 g of palm oil paraffin to 29.7 g of anhydrous ethanol, heat in a water bath at 80°C for 30 min to obtain a palm oil paraffin solution. Add 0.3 g of hydrophobic nano-silica to the palm oil paraffin solution, stir magnetically for 30 min to obtain a waterproofing agent.

[0056] Step 5: Fix the base paper on the roller coater and apply the oil-proof agent on the surface of the base paper through the roller coater. The coating amount is 4g / m 2 , then dry the base paper at 60°C and 50% relative humidity for 20 minutes; then place the base paper at room temperature for 24 hours.

[0057] Step 6: Immerse the base paper with the oil-proof coating in the waterproofing agent for 3 minutes. Then dry the base paper for 30 minutes at 35°C and 50% relative humidity, and then place the base paper at room temperature for 24 hours to obtain environmentally friendly oil-proof and waterproof packaging paper.

[0058] The raw material formula was changed according to Table 1, and the packaging papers of Examples 2 to 10 were prepared according to the preparation method of Example 1.

[0059] Table 1 Formulations of Examples and Comparative Examples

[0060]

[0061] 1. Water vapor barrier performance, the test process is as follows: according to standard ASTM-E96, the water vapor transmission rate is measured by using W3 / 062 water vapor transmission rate tester (weight gain method), the test temperature is (23±0.5)℃, and the humidity is (50±1)%RH.

[0062] 2. Tensile strength test: At humidity (50±1)% RH and temperature (30±1)°C, according to standard GB / T 12914-2018, a tensile tester was used to stretch the sample at a constant tensile speed (20 mm / min), and the sample width was (15±0.1) mm.

[0063] 3. Grease resistance test: refer to TAPPI T 559cm-02 "Grease resistance test for paper and paperboard" to evaluate the oil resistance of packaging paper.

[0064] 4. Example 1, Examples 7 to 10, and Comparative Example 1 were subjected to water absorption and oil absorption tests.

[0065] Table 2 Test results of embodiments and comparative examples

[0066]

[0067] 1. From the comparison of Examples 1 to 3, it can be seen that the mass ratio of chitosan solution to sodium alginate solution will affect its oil-proof performance. If the mass of chitosan solution in the oil-proof agent is more than that of sodium alginate solution, the oil-proof grade of the oil-proof coating will decrease. This is because the oil-proof performance of chitosan is better than that of sodium alginate. Moreover, if the mass of chitosan solution is more than that of sodium alginate solution, the strength of the packaging paper will be enhanced. This is because sodium alginate has a large viscosity and is difficult to lay flat on the base paper, resulting in uneven thickness of the formed oil-proof coating, thereby reducing the strength of the packaging paper. From the comparison of Examples 1 to 3, it can be seen that when the mass ratio of chitosan solution to sodium alginate solution is 8:2, the tensile strength and oil-proof performance of the packaging paper are the best.

[0068] 2. From the comparison of Examples 4 to 6, it can be seen that when the mass fraction of hydrophobic nano-silicon dioxide in the waterproofing agent is greater than or equal to 0.99%, the waterproof coating has excellent waterproof performance. When the mass fraction of hydrophobic nano-silicon dioxide in the waterproofing agent of Example 4 is less than 0.99%, the water vapor permeability of the packaging paper increases significantly, indicating that the waterproof performance of the waterproof coating is significantly weakened. Moreover, the more the mass fraction of hydrophobic nano-silicon dioxide and palm oil paraffin in the waterproof coating, the better the tensile strength of the packaging paper.

[0069] 3. The mass fraction ratio of ethanol, palm oil paraffin and hydrophobic nano-silicon dioxide in the waterproofing agents of Examples 1 and 7 to 10 is 29.7:0.3:0.3. From the comparison between Examples 1, 7 to 10 and Comparative Example 1, it can be seen that the amount of waterproofing agent applied to the packaging paper will affect its waterproof performance. Figure 1 As shown in the figure, as the amount of waterproofing agent applied to the packaging paper increases, its waterproof Cobb value decreases and its contact angle increases, indicating that the waterproof performance of the packaging paper is gradually improved. However, when the amount of waterproofing agent applied reaches 3g / m 2 After that, the Cobb value and contact angle of the packaging paper tend to be stable, and the packaging paper has achieved the best waterproof effect. Therefore, the optimal impregnation amount of the waterproofing agent is 3g / m 2 .

[0070] 4. The mass fraction ratio of chitosan solution to sodium alginate solution in the waterproofing agents of Examples 1 and 7 to 10 is 8:2. From the comparison between Examples 1, 7 to 10 and Comparative Example 1, it can be seen that the amount of oil-proofing agent applied to the packaging paper will affect its oil-proofing performance. Figure 2 As shown in the figure, the amount of waterproof agent applied to the packaging paper increases, and its oil resistance level improves. However, when the amount of oil-proof agent applied reaches 3g / m 2 After that, the oil-proof level of the packaging paper tends to be stable, and the packaging paper has achieved the best oil-proof effect, so the optimal impregnation amount of the waterproofing agent is 4g / m 2 .

[0071] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An environmentally friendly oil-proof and waterproof packaging paper, It is characterized in that The invention comprises base paper, the surface of the base paper is coated with an oil-proof agent to form an oil-proof coating, the oil-proof coating is coated with a waterproof agent to form a waterproof coating, the oil-proof agent comprises a chitosan solution, a sodium alginate solution, a cross-linking agent, and glycerol; the waterproof agent comprises a palm oil paraffin solution and hydrophobic nano-silica.

2. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The oil-proofing agent comprises the following raw materials in parts by mass: 50-90 parts of chitosan solution, 10-50 parts of sodium alginate solution, 0.1-0.3 parts of cross-linking agent, and 0.5 parts of glycerol, wherein the mass fraction of chitosan in the chitosan solution is 2%, and the mass fraction of sodium alginate in the sodium alginate solution is 1.5%.

3. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The cross-linking agent is 4-hydroxy-3-methoxycinnamic acid.

4. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The solvent of the chitosan solution is ionized water, and the chitosan solution includes glacial acetic acid as a co-solvent; the solvent of the sodium alginate solution is ionized water.

5. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The waterproofing agent comprises the following raw materials in parts by weight: 30-31 parts of palm oil paraffin solution and 0.3-0.6 parts of hydrophobic nano silicon dioxide. The mass fraction of the palm oil paraffin in the palm oil paraffin solution is 1%-3%.

6. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The solvent of the palm oil paraffin solution is ethanol.

7. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The base paper is coated with 1 to 5 g of oil-proofing agent per square meter.

8. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that The base paper is coated with 1 to 5 g of waterproofing agent per square meter.

9. A method for preparing an environmentally friendly oil-proof and waterproof packaging paper, used for preparing the environmentally friendly oil-proof and waterproof packaging paper according to any one of claims 1 to 8, It is characterized in that The following steps are involved: Step 1: adding glacial acetic acid to deionized water to obtain a glacial acetic acid solution; then adding chitosan to the glacial acetic acid solution, stirring and heating to obtain a chitosan solution; Step 2: adding sodium alginate into deionized water to obtain a sodium alginate solution; Step 3: Mix the chitosan solution with the sodium alginate solution, add a cross-linking agent to react for 20 to 40 minutes, and then add glycerol to react for 20 to 40 minutes to obtain an oil-proofing agent; Step 4: dissolving palm oil paraffin in ethanol and heating to obtain a palm oil paraffin solution; then adding hydrophobic nano-silica to the palm oil paraffin solution and stirring to obtain a waterproofing agent; Step 5: Drying the oil-proof agent on the surface of the base paper, and drying to form an oil-proof coating on the surface of the base paper; Step six: Apply the oil-proof agent on the surface of the oil-proof coating and dry it to obtain environmentally friendly oil-proof and waterproof packaging paper.

10. The environmentally friendly oil-proof and waterproof packaging paper according to claim 1, It is characterized in that In the step 5, the base paper is dried for 20 minutes at 60° C. and a relative humidity of 50%; and then the base paper is placed at room temperature for 24 hours; in the step 6, the base paper is dried for 30 minutes at 35° C. and a relative humidity of 50%, and then the base paper is placed at room temperature for 24 hours.

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