Food packaging film made of waste paper composite material and preparation method of food packaging film

Abstract

The invention discloses a waste paper composite food packaging film and a preparation method thereof, and the waste paper composite food packaging film mainly comprises waste recycled paper fibers, poly (butylene succinate) (PBS) modified by a compatilizer, silica aerogel and oyster shell powder, the waste recycled paper fibers, the poly (butylene succinate), the silica aerogel and the oyster shell powder are mixed together to form master batches, and the master batches are subjected to film blowing processing to form the food packaging film, so that the food packaging film has the advantages of low heat conductivity, antibacterial (antimicrobial) and the like, is used for packaging food, has a better effect and a better barrier effect, and can be widely applied to food packaging. And the raw material source is the waste recycled paper fiber, and the source is consistent and is easy to obtain, so that the material has the characteristic of being reused by the industry.

Description

Technical Field

[0001] The present invention relates to a food packaging film made of waste paper composite material with good barrier effect, excellent performance, and antibacterial (antimicrobial) advantages, and a preparation method thereof. Background Art

[0002] At the present stage, the paper-making industry is one of the basic industries for people's livelihood and an important basic material industry for the national economy. It has a great relevance to industries such as forestry, agriculture, printing, packaging, electronics, energy, and environmental protection. The raw materials of the paper-making industry mainly include plant fibers (such as wood, bamboo, rice straw, and wheat straw) and recycled fibers (such as waste paper). Through processes such as pulp making and papermaking, paper is produced. Although the number of paper mills in China has gradually decreased in recent years, and most of them are small and medium-sized enterprises, over the years, operators have introduced new technologies and equipment, and combined with downstream industries such as printing, paper products, and packaging. In the economic, cultural, and service supply chains formed, the upstream, midstream, and downstream industries of the paper-making industry can be distinguished. Through the upstream, midstream, and downstream of the paper-making industry, there is good connection, and it is still one of the sources to promote domestic economic development at present.

[0003] In addition, the traditional paper-making industry is a high-energy-consuming and high-pollution industry. Especially the wastewater after pulping is rich in solvents and a large amount of solids. It is easy to deposit after being discharged into water areas and will harm aquatic organisms. Therefore, the European Union plans to implement some measures for this problem. It is generally believed that this measure direction will have a major impact on industries such as chemistry and paper-making. Under the increasingly strict international environmental protection standards, industrial paper manufacturers respond to the high requirements of environmental protection regulations and gradually introduce a variety of new products using recycled materials, green packaging cartons, and lightweight products. In recent years, paper mills have actively promoted correct classification to recycled paper suppliers and strictly implemented the inspection of miscellaneous papers, sundries, and water content tolerance rates in the classified recycled paper. As a result, the waste utilization rate of paper mills exceeds 90%, which has reached the standards of advanced countries. It can not only reduce the use of virgin pulp in forests, but also solve the problems of waste incineration and carbon dioxide emissions of domestic recycled paper.

[0004] However, since waste paper waste belongs to plant fibers, it is prone to water absorption problems. After the product is in the air for a long time, the plant fibers will gradually be hydrolyzed and undergo a degradation reaction, significantly reducing the service life of the reinforcing plant fiber material.

[0005] Therefore, how to solve the above-mentioned problems and deficiencies in conventional use is the direction that the applicant of the present invention and relevant manufacturers in this industry are eager to research and improve. Summary of the Invention

[0006] The main object of the present invention is to provide a food packaging film made of waste paper composite material and its preparation method. By using a mixture of fiber materials filtered from waste recycled paper, environmentally friendly plastic materials formed by modifying polybutylene succinate (PBS), silica aerogel powder, and oyster shell powder, the food packaging film of this case will not produce toxic gases when burned after being discarded and recycled, having an environmental protection effect. Moreover, because the food packaging film of this case contains silica aerogel, through the reinforcement of the added environmentally friendly plastic material, the food packaging film of this case has excellent heat insulation performance, water repellency, and insulation properties, and can be widely applied to various industries, especially in food packaging films, which can increase the service life and has the advantage of protecting food; in addition, through oyster shell powder, the antibacterial effect and the advantage of resisting microorganisms can be enhanced.

[0007] To achieve the above main object, the present invention provides a food packaging film made of waste paper composite material and its preparation method. The food packaging film mainly includes waste recycled paper fibers, polybutylene succinate (PBS) modified by a compatibilizer, silica aerogel, and oyster shell powder. In the preparation method, waste recycled paper can be used as the raw material and filtered to screen out waste recycled paper fibers. Then, polybutylene succinate (PBS) is grafted with a compatibilizer to modify polybutylene succinate to form an environmentally friendly plastic material. Then, silica aerogel and oyster shell are respectively dispersed, and the dispersed silica aerogel and oyster shell are ground by a wet grinder. After grinding, high-temperature drying is carried out. After drying is completed, screening is carried out by a vibrating sieve to produce silica aerogel powder and oyster shell powder. In order to produce masterbatch, waste recycled paper fibers, environmentally friendly plastic materials, silica aerogel powder, and oyster shell powder are put into a twin-screw granulator for mixing to produce masterbatch. Then, the masterbatch is hot-pressed to form a thin plate, and the thin plate is placed into a twin-screw blown film machine for blown film. After the film is produced, it is extended to a coiler, and the coiler is used to coil the blown film into a roll to complete the food packaging film.

[0008] By the above technology, the problem of a significant decrease in the service life in conventional use can be overcome, achieving the practical progress of the present invention as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a three-dimensional schematic diagram of a preferred embodiment of the present invention.

[0010] Figure 2 It is the step flow of a preferred embodiment of the present invention Figure 1 。

[0011] Figure 3 It is the step flow of a preferred embodiment of the present invention Figure 2 。

[0012] Figure 4 Schematic diagram of the barrier for a preferred embodiment of the present invention.

[0013] Figure 5 Flow chart of the steps for another preferred embodiment of the present invention.

[0014] Figure 6 Flow chart of the steps for yet another preferred embodiment of the present invention.

[0015] Explanation of the reference numerals in the drawings: Food packaging film - 1; Waste recycled paper fiber - 11; Polybutylene succinate (PBS) - 12; Silica aerogel powder - 13; Oyster shell powder - 14; Water vapor - 2; Oxygen - 3. Detailed description of the specific implementation

[0016] Please refer to Figure 1 As shown, it is a three - dimensional schematic diagram of a preferred embodiment of the present invention. It can be clearly seen from the figure that the food packaging film 1 of the present invention includes waste recycled paper fiber 11, polybutylene succinate (PBS) 12 modified by a compatibilizer, silica aerogel, and oyster shells. And the waste recycled paper fiber 11, the polybutylene succinate (PBS) 12, the silica aerogel, and the oyster shells are mixed together to form masterbatch, and the food packaging film 1 is formed by blown film processing. And the compatibilizer can be one of maleic anhydride, polyacrylic acid, or tributyl acetyl citrate. In addition, the aforementioned silica aerogel and oyster shells are subjected to wet grinding and then oscillating screening to form silica aerogel powder 13 and oyster shell powder 14.

[0017] Please refer to Figure 2 As shown, it is the process flow Figure 1 of a preferred embodiment of the present invention. It can be clearly seen from the figure that the main steps of the present invention include (a) taking raw materials; (b) filtering and screening; (c) manufacturing environmentally friendly plastic materials; (d) dispersing silica aerogel and oyster shells; (e) wet - grinding silica aerogel and oyster shells; (f) drying silica aerogel and oyster shells; (g) oscillating and screening silica aerogel and oyster shells; (h) manufacturing masterbatch; (i) hot - pressing; (j) blown film; (k) using a coiler to form the blown film.

[0018] For the above - mentioned main steps, a more detailed description is as follows, and reference can also be made to Figures 2 to 4 as shown, Figures 2 to 4 is the process flow Figure 1 of a preferred embodiment of the present invention to the schematic diagram of the barrier:

[0019] (a) Taking raw materials: The main raw material is recycled waste paper. The reason for using recycled waste paper in this case is that it can reduce the use of virgin pulp, solve the problems of waste incineration and carbon dioxide emissions of recycled paper, enable the recycling and reuse of resources, return paper waste to products, and implement energy-saving and carbon-reduction policy measures.

[0020] (b) Filtering and screening: The raw materials are filtered to screen out recycled waste paper fibers. The filtering process described in this step mainly includes (b1) slag removal and deinking: After the raw materials are subjected to slag removal and deinking treatment, (b2) fiber screening treatment is then carried out. The fiber screening treatment method can be one of net pulp treatment, sulfuric acid acidification treatment, sodium hydroxide alkaline treatment, or water grinding treatment; among them, taking net pulp treatment as an example, the raw materials after slag removal and deinking treatment are subjected to (b3) high-temperature drying, and then (b4) vibration screening is carried out. After screening, it is washed with (b5) distilled water and (b6) secondary drying is carried out again. After drying, (b7) a grinder is used for crushing and vibration to screen out the recycled waste paper fibers mentioned above. In other words, the raw materials after slag removal and deinking of recycled waste paper contain more impurities such as plastics, rubber, glass, small stones, wood blocks, and artificial fibers. After the net pulp treatment process, when screening out fine inorganic impurities, fibers (fine paper pieces) can also be separated. This substance can be directly made into derivative fuel. Taking sulfuric acid acidification treatment as an example, strong acids such as sulfuric acid and phosphoric acid are used to hydrolyze the amorphous regions of cellulose. The remaining crystalline fragments have a diameter of 2 nm to 50 nm and a length of about several micrometers. The content of sulfate half-ester or phosphate ester groups generated on the surface of the cellulose crystal structure due to the action of strong acids is about 240 mmol / kg to 330 mmol / kg. Due to the mutual repulsion of anionic groups, cellulose nanocrystals (CNC) can be very stably dispersed in an aqueous solution. In addition, the solution has obvious liquid crystal behavior at high concentrations. The cellulose crystals obtained by this method also have a hydrophobic surface due to the absence of hydroxyl groups. Therefore, cellulose crystals have amphoteric properties of hydrophilicity and hydrophobicity, and their interfacial activity can make the oil-water emulsion uniform. Taking sodium hydroxide alkaline treatment as an example, because sodium hydroxide has the characteristic of not reacting with cellulose but being able to corrode and dissolve non-cellulose components, pulp mainly composed of cellulose is manufactured. The pulp is added with sodium hydroxide additives, and the pulp is transported into a medium-consistency mixer through a medium-consistency pulp pump. Before the pulp enters the medium-consistency mixer or when it is in the medium-consistency mixer, hydrogen peroxide accounting for 1.0% to 2.5% of the dry pulp weight is added, and steam is introduced to heat the pulp to a temperature of 70°C to 100°C. After the pulp bleaching reaction in the hydrogen peroxide bleaching tower ends, the pulp is diluted with water at the bottom of the tower and discharged, and after washing (or neutralization washing), bleached pulp is obtained;

[0021] (c) Fabricate environmentally friendly plastic materials: Take polybutylene succinate (PBS), graft a compatibilizer to modify polybutylene succinate to form an environmentally friendly plastic material, and the compatibilizer is one of maleic anhydride, polyacrylic acid or tributyl acetylcitrate.

[0022] Among them, the polybutylene succinate is characterized in that it is a plastic that can provide biodegradable function, which is a function that traditional plastics cannot provide. Therefore, it can become a substitute for traditional plastics and has many applications such as excellent biodegradability, biocompatibility, thermal processability and mechanical properties. Moreover, polybutylene succinate is essentially non-toxic, inert and hydrophobic. However, due to the poor strength and thermal stability of polybutylene succinate, this step is to modify polybutylene succinate to reduce the cost of the biomass composite material and enhance the biocompatibility, biodegradability and mechanical reinforcement of the composite material.

[0023] Among them, taking maleic anhydride as an example, the compatibilizer in this embodiment grafts maleic anhydride onto polybutylene succinate, which can increase the interfacial bonding force and maintain good biocompatibility. When the content of waste recycled paper fiber reaches 10 wt%, compared with ungrafted polybutylene succinate, the breaking tensile strength can be effectively improved. Therefore, when using maleic anhydride, polyacrylic acid or tributyl acetylcitrate as the compatibilizer, it can improve the phenomenon of weak interfacial adhesion between polybutylene succinate and waste recycled paper fiber, enable interfacial bonding, and also disperse the waste recycled paper fiber in polybutylene succinate, and further improve its mechanical properties.

[0024] Also, for the method of grafting a compatibilizer onto polybutylene succinate (PBS), first dry polybutylene succinate in a vacuum oven at a temperature of 65 °C - 85 °C for 7 hours - 9 hours, then take different contents of maleic anhydride (MA) and different contents of initiator benzoyl peroxide (BPO), with dichloromethane as the solvent, introduce nitrogen at a high temperature of 75 °C - 85 °C, and maintain a certain rotation speed for reaction for 2 hours - 20 hours to obtain the grafted polybutylene succinate copolymer, that is, the so-called environmentally friendly plastic material.

[0025] (d)Disperse silica aerogel and oyster shell: Take silica aerogel and oyster shell, and perform dispersion treatment on them. The so-called dispersion treatment is to use a twin-screw machine or a granulation system of an internal mixer to disperse silica aerogel and oyster shell. Among them, silica aerogel can present diversified forms such as powder, block or film. And in the structure, it has characteristics and advantages such as nano-pores, high specific surface area, low thermal conductivity, low dielectric constant and low refractive index. Therefore, it has high compressive strength, excellent heat insulation performance, water repellency and insulation properties. In terms of high specific surface area, due to the high proportion of porous structure on the surface of silica aerogel, it has good air permeability and adsorption properties. In terms of low thermal conductivity, silica aerogel has an extremely high porosity and its thermal conductivity is very low, better than that of general common rigid foam heat insulation materials. Therefore, it is an excellent heat insulation material. In terms of low dielectric constant, silica aerogel has an extremely low dielectric constant and can also be used as a high-efficiency insulating material. In terms of low light refractive index, because silica aerogel is rich in a large amount of air inside, it has a low light refractive index. Therefore, based on the above description of silica aerogel, after adding silica aerogel, it can make the food packaging film in this case generate a more tortuous path for blocking, reduce the permeability of carbon dioxide, nitrogen and oxygen, and improve the gas barrier performance, and is very suitable for application on food packaging films.

[0026] (e)Perform wet grinding on silica aerogel and oyster shell: Use a wet grinding machine to perform wet grinding on the dispersed silica aerogel and oyster shell. In other words, because silica aerogel may agglomerate during the grinding process, in this case, the wet grinding method is adopted so that silica aerogel will not agglomerate during the grinding process. And by using the wet grinding method, the refinement degree of silica aerogel and oyster shell can reach the nano-level or micron-level. Therefore, using a wet grinding machine can be more stable in terms of quality.

[0027] (f)Dry silica aerogel and oyster shell: Perform high-temperature drying on the silica aerogel and oyster shell after wet grinding.

[0028] (g)Perform vibration screening on silica aerogel and oyster shell: Use a vibration screening machine to screen the dried silica aerogel and oyster shell to produce silica aerogel powder and oyster shell powder. In addition, the oyster shell powder can also improve its ability to adsorb low-molecular-weight substances after the above treatment. And in the evaluation of the antibacterial and antifungal effects of oyster shell powder, it has the ability to inhibit Staphylococcus aureus, Escherichia coli, Listeria, Salmonella, Bacillus cereus, Micrococcus luteus, Aspergillus niger and Penicillium funiculosum, etc.

[0029] (h) Manufacturing masterbatch: The waste recycled paper fibers, environmentally friendly plastic materials, silica aerogel powder, and oyster shell powder are jointly put into a twin-screw granulator for blending (blending conditions: 135°C - 155°C and 150 rpm - 250 rpm) to produce masterbatch. Thus, through steps (e) to (h), problems such as different hydrophilic / hydrophobic properties and uneven dispersion can be prevented. Therefore, the aforementioned problems are improved by preheating and drying and side feeding of the twin-screw granulator respectively;

[0030] (i) Hot pressing: The masterbatch is hot pressed to form a thin plate. In other words, the masterbatch is placed in a hot pressing machine at a high temperature of 145°C - 155°C and pressed into a thin plate;

[0031] (j) Film blowing: The thin plate is placed into a twin-screw film blowing machine for film blowing to produce a film. Among them, during film blowing processing, situations such as phase separation or agglomeration may occur, resulting in damage to the quality of the food packaging film. In this regard, when reprocessing, lubricating oil is added to effectively reduce the friction of the thin plate in the screw and enhance its mixing; and

[0032] (k) Winding machine film blowing forming: The produced film is extended to a winding machine, and the film after film blowing is wound into a roll by using an existing winding machine on the market, and the winding machine can control the thickness to complete the food packaging film.

[0033] Thereby, reference can be made jointly to Figure 4 the shown barrier schematic diagram. When the above steps are completed, the food packaging film of this case can achieve an excellent heat insulation effect. Because the heat insulation effect of general plastics is poor, heat energy will quickly directly penetrate and the heat conduction speed is very fast. However, in this case, polybutylene succinate (PBS) 12 is modified by using waste recycled paper fibers 11 in combination with silica aerogel powder 13 and oyster shell powder 14, thereby forming relatively fine pores. When heat energy containing water vapor 2 and oxygen 3 passes through the food packaging film of this case, it will produce a turning or swirling phenomenon and is not easy to directly penetrate, resulting in a slower heat conduction speed and an excellent heat insulation effect.

[0034] Please refer to Figure 5 shown in the flowchart of the steps of another preferred embodiment of the present invention. It can be clearly seen from the figure that the difference between this embodiment and the above embodiment is that in this embodiment, after step (a), step (a1) pulping treatment can be carried out: The raw materials are pulped by using an existing pulper on the market to form a pulp state, so that the subsequent filtration treatment step can proceed more smoothly.

[0035] Please refer to Figure 6As shown, it is a flowchart of the steps of another preferred embodiment of the present invention. It can be clearly seen from the figure that the difference between this embodiment and the above-mentioned embodiment is that after step (i), step (i1) can be carried out for data testing. This step mainly conducts property analysis, cytotoxicity testing, barrier testing, hydrophobicity analysis, biodegradable / bio-based content testing, and functional testing on thin plates, etc., to confirm that the quality is satisfactory. Taking cytotoxicity testing as an example, a culture medium is prepared, then frozen and activated, and then placed in a cell box. By means of film lamination and material extraction, a toxicity test is carried out on the film to know whether the material has biological toxicity. In this way, it can be known whether the test substance causes harm or influence to cells. Taking barrier testing as another example, high-purity oxygen is used to test the oxygen barrier performance, and a water vapor transmission rate system is used to test the water vapor barrier performance. Taking hydrophobicity analysis as an example, a vacuum oven is used to test the hydrophobicity.

[0036] Although various embodiments of the present invention have been shown and described herein, these embodiments are provided by way of example only. Any operating theory or benefits provided herein are only for the purpose of explaining the present invention as an aid; such theories and explanations do not bind or limit the claims regarding tissue remodeling achieved by practicing the present invention. Those skilled in the art can conceive of many variations, changes, or alternatives without departing from the present invention. It should be understood that various alternatives of the embodiments of the invention described herein can be adopted in practicing the present invention. The scope of the present invention, the methods and structures within the scope of the present invention are intended to include equivalent forms.

Claims

1. A food packaging film made of waste paper composite material, characterized in that: This food packaging film mainly contains waste recycled paper fibers, polybutylene succinate (PBS) modified by a compatibilizer, silica aerogel and oyster shells, and the waste recycled paper fibers, the polybutylene succinate, the silica aerogel and the oyster shells are mixed together to form masterbatch and processed by blown film to form this food packaging film.

2. The food packaging film made of waste paper composite material according to claim 1, characterized in that: This compatibilizer is one of maleic anhydride, polyacrylic acid or tributyl acetylcitrate.

3. The food packaging film made of waste paper composite material according to claim 1, characterized in that: The silica aerogel and oyster shells are wet ground with water and then subjected to vibration screening to form silica aerogel powder and oyster shell powder.

4. A preparation method of a food packaging film made of waste paper composite material, characterized in that: The main preparation steps of this food packaging film include: (a) Using waste recycled paper as raw material; (b) Filtering the raw material to screen out waste recycled paper fibers; (c) Taking polybutylene succinate (PBS) and grafting a compatibilizer to modify the polybutylene succinate to form an environmentally friendly plastic material; (d) Taking silica aerogel and oyster shells and dispersing the silica aerogel and oyster shells; (e) Wet grinding the dispersed silica aerogel and oyster shells with a wet water grinding machine; (f) High-temperature drying the silica aerogel and oyster shells after water grinding; (g) Using a vibration screening machine to screen the dried silica aerogel and oyster shells to produce silica aerogel powder and oyster shell powder; (h) Putting the waste recycled paper fibers, the environmentally friendly plastic material, the silica aerogel powder and the oyster shell powder together into a twin-screw granulator for mixing to produce masterbatch; (i) Thermally pressing the masterbatch to form a thin plate; (j) Putting the thin plate into a twin-screw blown film machine for the blown film step to produce a film; and (k) Extending the produced film to a coiler and using the coiler to coil the blown film into a roll to complete this food packaging film.

5. The preparation method of the food packaging film made of waste paper composite material according to claim 4, characterized in that: This compatibilizer is one of maleic anhydride, polyacrylic acid or tributyl acetylcitrate.

6. The preparation method of the food packaging film made of waste paper composite material according to claim 4, characterized in that: After step (a), step (a1) can be carried out to disperse the raw material with a pulper.

7. The preparation method of the food packaging film made of waste paper composite material according to claim 4, characterized in that: In the filtering treatment step of step (b), after the raw material is subjected to slag removal and deinking treatment, fiber screening treatment is carried out.

8. The preparation method of the food packaging film made of waste paper composite material according to claim 7, characterized in that: The way of this fiber screening treatment can be one of sizing treatment, sulfuric acid acidification treatment, sodium hydroxide alkaline treatment, or aqueous grinding treatment.

9. The preparation method of the food packaging film made of waste paper composite material according to claim 8, characterized in that: For the sizing material treatment, the raw materials after residue discharging and deinking treatment are dried at high temperature, then subjected to vibration screening. After the screening is completed, they are washed with distilled water and dried again. After drying is completed, they are crushed and vibrated using a grinding machine to screen out the waste recycled paper fibers as described above.

10. The method for preparing the food packaging film of the waste paper composite material according to claim 6, characterized in that: After step (i), step (i1) can be carried out for data testing.

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