Fluorine-free bio-based membrane transfer oil-proof paper as well as preparation method and application thereof

Abstract

The invention discloses fluoride-free bio-based membrane transfer oil-proof paper as well as a preparation method and application thereof, and belongs to the technical field of oil-proof paper. The preparation method comprises the following steps: adding Tempo oxidized nanocellulose gel into water, dispersing the Tempo oxidized nanocellulose gel into a uniform solution through a high-speed dispersion machine, and adding hyaluronic acid into water to obtain a hyaluronic acid solution; mixing the Tempo oxidized nanocellulose solution and a hyaluronic acid solution according to a mass ratio of 7: 3-3: 7, casting the mixture into a plastic plate, and then evaporating the solvent to form a thin film; and soaking the obtained film in a calcium chloride solution, washing with deionized water, transferring to kraft paper, and drying to obtain the fluoride-free bio-based film transfer oil-proof paper. The fluoride-free bio-based membrane transfer oil-proof paper provided by the invention has excellent oil-proof performance, the oil-proof grade reaches 12 grade, and no edible oil permeates 30 minutes after edible oil at 230 + / -5 DEG C is dripped into the fluoride-free bio-based membrane transfer oil-proof paper; the raw materials do not contain fluorine and are derived from a bio-based material, so that the material is biodegradable and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of greaseproof paper, and particularly to a fluorine-free bio-based film-transfer greaseproof paper and its preparation method and application. Background Art

[0002] With the in-depth promotion of the global "plastic restriction order", paper-based packaging materials have become an important choice to replace disposable plastic products due to their characteristics such as renewable, biodegradable and lightweight. However, the inherent porous structure of paper-based materials leads to significant defects when directly applied to greaseproof packaging. Currently, the industry mainly uses two technical means to improve the greaseproof performance of paper-based materials: one is surface laminating, although it can effectively block oil penetration, the composite plastic layer significantly destroys the recyclability and biodegradability of the material, and essentially fails to solve the problem of white pollution; the other is the modification technology of low surface energy substances, by using fluorine-containing polymers with low surface energy to significantly reduce the surface energy of paper-based materials, making them have greaseproof or even oil-repellent properties, but the harm of fluorine-containing polymers to human health and the environment has been explicitly prohibited by many countries. Therefore, the development of a fluorine-free bio-based greaseproof paper with high greaseproof performance and environmental friendliness is regarded as a more sustainable solution.

[0003] Patent CN110195373A discloses a method for preparing food greaseproof paper using bio-based materials such as sodium alginate, but the greaseproof effect is limited, and the highest greaseproof grade is 10. Patent CN116695483A discloses a method for preparing a greaseproof coating using petroleum-based compounds such as acrylic resin. In the case of using petroleum-based compounds, the highest greaseproof effect is 10, and the acrylic resin used has poor degradation ability and is not environmentally friendly. Patent CN119570317A discloses a highly greaseproof fluorine-containing composition coating with good greaseproof performance, but fluorine-containing compounds not only put pressure on the environment, but also have safety risks of bioaccumulation and affecting human health. Summary of the Invention

[0004] Aiming at the deficiencies of current greaseproof paper, in order to improve the greaseproof effect of greaseproof paper and prepare greaseproof paper with a high safety factor that can be applied to food packaging, the purpose of the present invention is to provide a fluorine-free bio-based film-transfer greaseproof paper and its preparation method and application.

[0005] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0006] A preparation method of a fluorine-free bio-based film-transfer greaseproof paper provided by the present invention includes the following steps:

[0007] (1) Adding Tempo-oxidized nanocellulose gel to water and dispersing it into a uniform Tempo-oxidized nanocellulose solution through a high-speed disperser, and adding hyaluronic acid to water to obtain a hyaluronic acid solution;

[0008] (2) Mix the above two solutions in proportion and cast them in a plastic petri dish, and then evaporate the solvent to form a film;

[0009] (3) Add calcium chloride to water to obtain a calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution, rinse it with deionized water, and then transfer it to kraft paper for drying to obtain the fluorine-free bio-based film transfer greaseproof paper.

[0010] Further, in step (1), the carboxyl content in the Tempo-oxidized nanocellulose gel is 1.6 - 2.0 mmol / g.

[0011] Further, in step (1), the rotation speed of the high-speed disperser is 8000 - 12000 r / min.

[0012] Further, in step (1), the concentration of the Tempo-oxidized nanocellulose solution is 0.6 - 0.8 wt%. The concentration of the Tempo-oxidized nanocellulose solution is preferably 0.6 wt%.

[0013] Further, in step (1), the concentration of the hyaluronic acid solution is 0.8 - 1.2 wt%. The concentration of the hyaluronic acid solution is preferably 1.0 wt%.

[0014] Further, in step (2), the mass ratio of the Tempo-oxidized nanocellulose solution to the hyaluronic acid solution is 7:3 - 3:7. The mass ratio of the Tempo-oxidized nanocellulose solution to the hyaluronic acid solution is preferably 1:1.

[0015] Further, in step (2), the evaporation of the solvent is carried out in an oven, the temperature of the oven is 40 - 60 °C, and the drying time is 8 - 12 h.

[0016] Further, in step (3), the concentration of the calcium chloride solution is 1.5 - 3.0 wt%.

[0017] Further, in step (3), the soaking time of the film is 60 - 150 min; the drying temperature is 20 - 30 °C, and the drying time is 12 - 24 h.

[0018] The present invention provides a fluorine-free bio-based film transfer greaseproof paper prepared by the above preparation method.

[0019] The fluorine-free bio-based film transfer greaseproof paper provided by the present invention can be applied in food packaging, and is particularly suitable for food packaging with high oil content.

[0020] Compared with the prior art, the present invention has the following advantages and effects:

[0021] (1) The preparation method provided by the present invention uses a fluorine-free biobased material as the raw material, which has a wide source and is renewable. The raw material does not contain petroleum-based compounds that are difficult to degrade and high-risk fluorine-containing compounds, is environmentally friendly and green, and is easy to degrade.

[0022] (2) For the fluorine-free biobased film-transfer greaseproof paper of the present invention, the mass ratio of the Tempo-oxidized nanocellulose solution to the hyaluronic acid solution is 7:3 - 3:7. The formed greaseproof film has a fast film-forming speed and a smooth film surface, shortening the processing time of the greaseproof paper. At the same time, the present invention immerses the film formed by the above composite solution in a calcium chloride solution to densify the film.

[0023] (3) The preparation method provided by the present invention can effectively fill the pores existing in kraft paper by means of film transfer, thereby preventing oil penetration.

[0024] (4) The preparation method provided by the present invention, the obtained fluorine-free biobased film-transfer greaseproof paper has good barrier properties to hot water or hot oil, and the greaseproof grade is as high as 12 / 12 level. After dropping hot oil at 230 ± 5 °C on the surface for 30 min, no penetration occurs on the paper. Detailed implementation mode

[0025] The following further illustrates the specific implementation of the present invention in combination with examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that for the processes not specifically described in detail below, those skilled in the art can implement or understand them with reference to the prior art. For reagents or instruments whose manufacturers are not indicated, they are regarded as conventional products that can be obtained through commercial purchase.

[0026] Example 1

[0027] A preparation method of a fluorine-free biobased film-transfer greaseproof paper includes the following steps:

[0028] (1) Add Tempo-oxidized nanocellulose gel with a carboxyl content of 1.6 mmol / g to water and disperse it into a 0.8 wt% solution by a high-speed disperser at a rotation speed of 10,000 r / min. Add hyaluronic acid to water and dissolve it to obtain a 1.0 wt% hyaluronic acid solution;

[0029] (2) Mix the above two solutions evenly at a mass ratio of 1:1, then cast them in a plastic petri dish, and evaporate the solvent in an oven at 60 °C to form a film;

[0030] (3) Add calcium chloride to water to obtain a 1.5 wt% calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution for 60 min, then rinse it with deionized water, and then transfer it to kraft paper and dry it at 25 °C to obtain the fluorine-free biobased film-transfer greaseproof paper.

[0031] The oil resistance of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 1 was measured according to TAPPI T 557cm-02, and the heat-resistant oil property was measured with reference to GB / T 36392-2018, where the test temperature of the edible oil was increased to 230 ± 5 °C and the test time was increased to 30 min.

[0032] It was measured that the oil resistance grade of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 1 reached the highest 12 / 12 grade, and there was still no penetration of edible oil 30 min after the edible oil was dropped at 230 ± 5 °C.

[0033] Example 2

[0034] A preparation method of a fluorine-free bio-based film transfer greaseproof paper includes the following steps:

[0035] (1) Add Tempo-oxidized nanocellulose gel with a carboxyl content of 1.6 mmol / g to water and disperse it into a 0.6 wt% solution by a high-speed disperser at a rotation speed of 8000 r / min. Dissolve hyaluronic acid in water to obtain a 1.0 wt% hyaluronic acid solution;

[0036] (2) Mix the above two solutions evenly at a mass ratio of 1:1, then cast them in a plastic petri dish, and evaporate the solvent in an oven at 50 °C to form a film;

[0037] (3) Add calcium chloride to water to obtain a 2.0 wt% calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution for 90 min, then rinse it with deionized water, and then transfer it to kraft paper and dry it at 30 °C to obtain the fluorine-free bio-based film transfer greaseproof paper.

[0038] The oil resistance of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 2 was measured according to TAPPI T 557cm-02, and the heat-resistant oil property was measured with reference to GB / T 36392-2018, where the test temperature of the edible oil was increased to 230 ± 5 °C and the test time was increased to 30 min.

[0039] It was measured that the oil resistance grade of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 2 reached the highest 12 / 12 grade, and there was still no penetration of edible oil 30 min after the edible oil was dropped at 230 ± 5 °C.

[0040] Example 3

[0041] A preparation method of a fluorine-free bio-based film transfer greaseproof paper includes the following steps:

[0042] (1) Add the Tempo-oxidized nanocellulose gel with a carboxyl content of 2.0 mmol / g to water and disperse it into a 0.6 wt% solution at a speed of 12,000 r / min by a high-speed disperser. Dissolve hyaluronic acid in water to obtain a 1.0 wt% hyaluronic acid solution;

[0043] (2) Mix the above two solutions evenly at a mass ratio of 1:1 and then cast them in a plastic petri dish. Evaporate the solvent in an oven at 40 °C to form a film;

[0044] (3) Add calcium chloride to water to obtain a 3.0 wt% calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution for 120 min, then rinse it with deionized water, and then transfer it to kraft paper and dry it at 20 °C to obtain the fluorine-free bio-based film transfer greaseproof paper.

[0045] The oil-proof performance of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 3 was measured according to TAPPI T 557 cm-02, and the heat-resistant oil performance was measured with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230 ± 5 °C, and the test time was increased to 30 min.

[0046] It was measured that the oil-proof grade of the fluorine-free bio-based film transfer greaseproof paper prepared in Example 3 reached the highest 12 / 12 level, and there was still no penetration of edible oil 30 min after the edible oil was dropped at 230 ± 5 °C.

[0047] Example 4

[0048] A preparation method of fluorine-free bio-based film transfer greaseproof paper, comprising the following steps:

[0049] (1) Add the Tempo-oxidized nanocellulose gel with a carboxyl content of 2.0 mmol / g to water and disperse it into a 0.6 wt% solution at a speed of 8,000 r / min by a high-speed disperser. Dissolve hyaluronic acid in water to obtain a 1.0 wt% hyaluronic acid solution;

[0050] (2) Mix the above two solutions evenly at a mass ratio of 1:1 and then cast them in a plastic petri dish. Evaporate the solvent in an oven at 60 °C to form a film;

[0051] (3) Add calcium chloride to water to obtain a 2.0 wt% calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution for 90 min, then rinse it with deionized water, and then transfer it to kraft paper and dry it at 30 °C to obtain the fluorine-free bio-based film transfer greaseproof paper.

[0052] The oil-proof performance of the fluorine-free bio-based film-transfer proof oil paper prepared in Example 4 was measured according to TAPPI T 557cm-02, and the heat-resistant oil performance was measured with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230±5°C, and the test time was increased to 30 min.

[0053] It was measured that the oil-proof grade of the fluorine-free bio-based film-transfer proof oil paper prepared in Example 4 reached the highest 12 / 12 grade, and there was no penetration of edible oil after 30 min when the edible oil was dropped at 230±5°C.

[0054] Example 5

[0055] A preparation method of a fluorine-free bio-based film-transfer proof oil paper includes the following steps:

[0056] (1) Add Tempo-oxidized nanocellulose gel with a carboxyl content of 1.8 mmol / g to water and disperse it into a 0.6 wt% solution by a high-speed disperser at a rotation speed of 12000 r / min. Dissolve hyaluronic acid in water to obtain a 1.2 wt% hyaluronic acid solution;

[0057] (2) Mix the above two solutions evenly at a mass ratio of 7:3, then cast them in a plastic petri dish, and evaporate the solvent in an oven at 50°C to form a film;

[0058] (3) Add calcium chloride to water to obtain a 1.5 wt% calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution for 60 min, then rinse it with deionized water, and then transfer it to kraft paper and dry it at 25°C to obtain the fluorine-free bio-based film-transfer proof oil paper.

[0059] The oil-proof performance of the fluorine-free bio-based film-transfer proof oil paper prepared in Example 4 was measured according to TAPPI T 557cm-02, and the heat-resistant oil performance was measured with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230±5°C, and the test time was increased to 30 min.

[0060] It was measured that the oil-proof grade of the fluorine-free bio-based film-transfer proof oil paper prepared in Example 5 reached the highest 12 / 12 grade, and there was no penetration of edible oil after 30 min when the edible oil was dropped at 230±5°C.

[0061] Comparative Example 1

[0062] Omit the preparation step of the Tempo-oxidized nanocellulose solution in step (1) of Example 1, that is, mix the Tempo-oxidized nanocellulose solution and the hyaluronic acid solution evenly at a mass ratio of 0:1 and then cast them. Other operating conditions are the same as those in Example 1 to obtain the proof oil paper.

[0063] The oil-proof performance of the oil-proof paper prepared in Comparative Example 1 was determined in accordance with TAPPI T 557cm-02, and the heat-resistant oil performance was determined with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230 ± 5 °C, and the test time was increased to 30 min.

[0064] The oil-proof grade of the fluorine-free bio-based film transfer oil-proof paper prepared in Comparative Example 1 was measured to be 2 / 12, and obvious penetration occurred 30 min after the edible oil was dropped at 230 ± 5 °C.

[0065] Comparative Example 2

[0066] Step (3) of Example 2 was omitted, and the solution in step (2) was directly coated on the paper in proportion to obtain the oil-proof paper, and other operating conditions were the same as those in Example 2.

[0067] The oil-proof performance of the oil-proof paper prepared in Comparative Example 2 was determined in accordance with TAPPI T 557cm-02, and the heat-resistant oil performance was determined with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230 ± 5 °C, and the test time was increased to 30 min.

[0068] The oil-proof grade of the fluorine-free bio-based film transfer oil-proof paper prepared in Comparative Example 2 was measured to be 7 / 12, and obvious penetration occurred 30 min after the edible oil was dropped at 230 ± 5 °C.

[0069] Comparative Example 3

[0070] The Tempo-oxidized nanocellulose solution in Example 3 was replaced with a cellulose nanofiber solution of the same concentration, and other operating conditions were the same as those in Example 3.

[0071] The oil-proof performance of the oil-proof paper prepared in Comparative Example 3 was determined in accordance with TAPPI T 557cm-02, and the heat-resistant oil performance was determined with reference to GB / T 36392-2018. The test temperature of the edible oil was increased to 230 ± 5 °C, and the test time was increased to 30 min.

[0072] The oil-proof grade of the fluorine-free bio-based film transfer oil-proof paper prepared in Comparative Example 3 was measured to be 3 / 12, and obvious penetration occurred 30 min after the edible oil was dropped at 230 ± 5 °C.

[0073] Table 1 Performance test data of the products obtained in each example and each comparative example

[0074] Oil-proof grade 30 min after 230 ± 5 °C edible oil is dropped Example 1 12 No penetration Example 2 12 No penetration Example 3 12 No penetration Example 4 12 No penetration Example 5 12 No penetration Comparative example 1 2 Obvious penetration Comparative example 2 7 Obvious penetration Comparative example 3 3 Obvious penetration

[0075] As can be seen from Table 1, the present invention uses a mixed solution formed by compounding a Tempo-oxidized nanocellulose solution and a hyaluronic acid solution to obtain a film, and immerses the film in a calcium chloride solution to successfully prepare a fluorine-free bio-based film transfer greaseproof paper. The coordination of calcium ions with carboxyl groups densifies the film, thereby improving the greaseproof effect. The greaseproof grade of the greaseproof paper prepared by the method of the present invention reaches the highest 12 / 12 level, and it can be used for packaging high-temperature hot oil without oil leakage for a long time (≥30 min).

[0076] The above embodiments are only relatively preferred embodiments of the present invention, and are only used to explain the present invention, rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit and essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A preparation method of a fluorine-free bio-based film transfer greaseproof paper, characterized in that, It includes the following steps: (1) Add Tempo-oxidized nanocellulose gel into water and disperse it into a uniform Tempo-oxidized nanocellulose solution by a high-speed disperser. Add hyaluronic acid into water to obtain a hyaluronic acid solution; (2) Mix the above two solutions in proportion and cast them in a plastic petri dish, and then evaporate the solvent to form a film; (3) Add calcium chloride into water to obtain a calcium chloride solution. Immerse the film obtained in step (2) in the calcium chloride solution, rinse it with deionized water, and then transfer it to kraft paper for drying to obtain the fluorine-free bio-based film transfer greaseproof paper.

2. The preparation method according to claim 1, characterized in that, In step (1), the carboxyl content in the Tempo-oxidized nanocellulose gel is 1.6 - 2.0 mmol / g.

3. The preparation method according to claim 1, characterized in that, In step (1), the rotation speed of the high-speed disperser is 8000 - 12000 r / min.

4. The preparation method according to claim 1, wherein In step (1), the concentration of the Tempo-oxidized nanocellulose solution is 0.6 - 0.8 wt%; the concentration of the hyaluronic acid solution is 0.8 - 1.2 wt%.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the Tempo-oxidized nanocellulose solution to the hyaluronic acid solution is 7:3 - 3:

7.

6. The preparation method according to claim 1, characterized in that, In step (2), the evaporation of the solvent is carried out in an oven. The temperature of the oven is 40 - 60 °C, and the drying time is 8 - 12 h.

7. The preparation method according to claim 1, characterized in that, In step (3), the concentration of the calcium chloride solution is 1.5 - 3.0 wt%.

8. The preparation method according to claim 1, wherein, In step (3), the soaking time of the film is 60 - 150 min; the drying temperature is 20 - 30 °C, and the drying time is 12 - 24 h.

9. The fluorine-free bio-based film transfer greaseproof paper obtained by the preparation method according to any one of claims 1 - 8.

10. The application of the fluorine-free bio-based film transfer greaseproof paper according to claim 9 in food packaging.