Plastic-free aluminum-free high-barrier food packaging paper and manufacturing method thereof

Abstract

The invention discloses plastic-free aluminum-free high-barrier food packaging paper and a manufacturing method thereof, and the method comprises the following steps: taking 50-55% of sulfate needlebush chemical pulp and 40-45% of sulfate chemical bamboo pulp as fiber raw materials according to a mass ratio; the high-barrier food packaging paper is obtained through pulping, pulp mixing, net forming, squeezing, first-time drying, sizing material auxiliary agent dipping, second-time drying, first-time surface coating, third-time drying and second-time surface coating in sequence. The first surface coating adopts a nanoscale water-based acrylic acid copolyester material, and the room temperature viscosity is 150-250 mPa.s; the second surface coating adopts a water-based carbon chain block acrylate polymer material; the coating weight of the first surface coating is not lower than that of the second surface coating. The food packaging paper disclosed by the invention has an excellent barrier function and excellent mechanical properties, does not need plastic film spraying and aluminum plating compounding, and is beneficial to promoting environment-friendly and recyclable development.

Description

Technical Field

[0001] The invention relates to the technical field of paper products, and in particular to a plastic-free and aluminum-free high-barrier food packaging paper and a manufacturing method thereof. Background Art

[0002] In recent years, my country's economy has developed rapidly, people's living standards have been greatly improved, and the development of the food packaging industry has been greatly promoted; food packaging has achieved remarkable achievements in many aspects such as appearance, material and practicality. Among them, with the increasing consumption of packaged food, the proportion of food packaging in domestic waste is also increasing.

[0003] High barrier packaging materials are essential materials for packaging of food, medicine, precision electronics and other products at home and abroad. At present, the main method of preparing high barrier packaging materials is: using paper as the base, and its surface is composited with multi-layer PE coating and aluminum-plated PET to form composite packaging paper. Although its barrier performance is good, after the PE coating and aluminum-plated PET composite materials have completed their packaging use value, it is difficult to recycle a variety of chemical materials, which not only increases the processing load of domestic waste, but also causes serious "white" pollution to the environment. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a plastic-free and aluminum-free high-barrier food packaging paper and a manufacturing method. The food packaging paper of the present invention has excellent barrier function and excellent mechanical properties, does not require plastic lamination and aluminum plating, and is conducive to promoting environmentally friendly, green and recyclable development.

[0005] The invention provides a method for manufacturing plastic-free and aluminum-free high-barrier food packaging paper, comprising the following steps: using 50-55% of sulfate coniferous wood chemical pulp and 40-45% of sulfate chemical bamboo pulp as fiber raw materials according to a mass ratio, and sequentially performing pulping, pulping, net forming, pressing, first drying, impregnation with a sizing agent, second drying, first surface coating, third drying, and second surface coating to obtain the high-barrier food packaging paper;

[0006] The first surface coating is made of nano-scale water-based acrylic copolyester material with a room temperature viscosity of 150-250 mPa·s; the second surface coating is made of water-based carbon chain block acrylic polymer material; the coating amount of the first surface coating is not less than the coating amount of the second surface coating, and the coating amount of the second surface coating is 3-5 g / m 2 .

[0007] At present, there is almost no environmentally friendly paper suitable for high-barrier food packaging purposes at home and abroad. The development of this plastic-free and aluminum-free high-barrier food packaging paper will play a positive role in solving the key technical difficulties of high oxygen and water vapor permeability requirements for food packaging using paper instead of plastic, and promoting environmentally friendly, green and recyclable development.

[0008] In order to achieve the above requirements, the embodiment of the present invention adopts the following technical scheme, which uses 50-55% sulfate coniferous wood chemical pulp and 40-45% sulfate chemical bamboo pulp as fiber raw materials for pulping. Among them, in order to make the base paper better meet the barrier coating requirements, the homemade bio-enzyme mixed auxiliary agent YZ-01A (made by cationic bio-enzyme and non-ionic guar gum in a weight ratio of 2:1, wherein the suitable temperature of the bio-enzyme is 60-80°C, the pH value is 7.0-8.0; the density of guar gum is 0.6-0.8g / l, the viscosity is 0.8-1.0cps, and the effective content is ≥98%) can be used to assist in pulping. In order to obtain excellent barrier properties, the embodiment of the present invention mainly adopts the "1+2" ​​sizing and coating process. First, the first sizing is an immersion sizing process, using a non-glue paper base paper, that is, no sizing in the pulp, and an over-immersion sizing machine. The sizing amount is preferably controlled at 15-20g / m 2 , so that Beijing Lipu LP-301 sizing agent penetrates into the fiber and between the fibers, so that the paper obtains preliminary barrier functions such as waterproof, oil-proof, and enhanced flexibility, and is conducive to reducing the amount of sizing liquid migrating into the paper during the next coating. Secondly, the paper after soaking and sizing is preferably subjected to two film transfer surface coatings. The first surface coating is carried out using Shanghai Xianke barrier material ZG-1 nano-level water-based narrow molecular weight acrylic copolyester, and the coating amount can be controlled at 5-8g / m 2 , so that the paper has a higher waterproof, moisture-proof, oil-proof and oxygen-proof effect. The second surface coating is carried out with Shanghai Xianke ZG-2 carbon chain block homopolymerized water-based acrylic polymer, and the coating amount is controlled at 3.0-5.0g / m 2 , ensuring that the paper has excellent waterproof, moisture-proof, oil-proof, oxygen-proof, acid-alkali-resistant and heat-sealable effects. The paper product specifically goes through: pulp crushing, pulping machine, pulping tank, pulping tank, sand removal, screening, net forming, composite pressing, first drying, soaking sizing agent, second drying, first surface coating, third drying, second surface coating, fourth drying, calendering, winding, packaging and storage.

[0009] The fiber raw materials in the embodiment of the present invention are sulphate chemical coniferous wood pulp (abbreviated as coniferous pulp, chemical coniferous pulp, coniferous chemical pulp, etc.) and sulphate chemical bamboo pulp (abbreviated as bamboo pulp, chemical bamboo pulp), and the pulp weight ratio is: 50-55% coniferous pulp: 40-45% bamboo pulp. The embodiment of the present invention adopts chemical coniferous pulp and chemical bamboo pulp for copying, the main purpose of which is to save limited coniferous wood resources, make full use of the complementary performance advantages of bamboo pulp and coniferous pulp, and improve the uniformity, tightness and bursting index of paper.

[0010] Furthermore, the fiber length of the kraft chemical coniferous wood pulp is generally 2.35-2.6 mm, the width is 33.0-356.0 μm, the wet weight is 15-18 g, and the beating degree is 13-15.5°SR; the fiber has the characteristics of good softness and high strength. The beating degree of the chemical bamboo pulp can be 12.5-15.0°SR, the wet weight is 10-13 g, the fiber length is 1.5-2.0 mm, and the width is 23.0-26.0 μm; the bamboo pulp has the advantages of natural antibacterial, good stability, and strong water absorption, which is conducive to increasing the absorption of the glue during the impregnation process.

[0011] Preferably, the beating degree of the kraft coniferous wood chemical pulp is 13-15.5°SR; the beating degree of the kraft chemical bamboo pulp is 12.5-15.0°SR.

[0012] In the process of manufacturing high-barrier food packaging paper in the embodiment of the present invention, the fibers are matched using a scientific ratio and high-efficiency composite additive-assisted pulping technology, fully utilizing the performance of chemical coniferous pulp and chemical bamboo pulp to achieve complementary advantages, while ensuring the uniformity and tightness of the paper, it also achieves the purpose of energy saving and saving forest resources.

[0013] Specifically, the present invention adopts a self-made biological enzyme mixed auxiliary agent YZ~01 to assist pulping. The mixed auxiliary agent is prepared by cationic biological enzyme and non-ionic guar gum in a weight ratio of 2:1, wherein the suitable temperature of the biological enzyme is 60-80°C and the pH value is 7.0-8.0; the density of guar gum is 0.6-0.8g / l, the viscosity is 0.8-1.0cps, and the effective content is ≥98%, and the same applies to the following; the YZ~01 mixed auxiliary agent has excellent surface activity, and can effectively adsorb onto pulp fibers with negative charges, promote fiber swelling, and make the fibers more evenly subjected to mechanical action; at the same time, it can improve the lubricity between fibers, promote fiber fibrillation during pulping, and reduce fiber cutting; improve the uniformity, flexibility and fineness of the base paper, thereby achieving the purpose of improving paper strength and saving pulping energy consumption.

[0014] Preferably, the beating is assisted by a self-made bio-enzyme mixed auxiliary agent YZ-01, which is composed of a cationic bio-enzyme and a non-ionic hydroxypropyl guar gum. Furthermore, in the beating step, the YZ-01 mixed auxiliary agent is a mixture of a cationic bio-enzyme and a non-ionic hydroxypropyl guar gum, and the weight ratio is preferably 2:1; it can be added to the pre-beating pulp pool in a continuous addition manner, and the dosage is preferably 2.0-3.5 kg / ton of pulp.

[0015] Further preferably, the mixed pulp of kraft coniferous wood chemical pulp and kraft chemical bamboo pulp has a pulping concentration of 4.5-5.5%, a beating degree of 42-48°SR, and a wet weight of 6.5-11.0 g.

[0016] The present invention is prepared into a 0.35-0.5% slurry, which is screened and purified before being put on the screen for papermaking, and the paper weight is controlled at 70-80g / m 2 The unsizing base paper is pressed and dried to 94-95% dryness before entering the immersion sizing equipment for treatment. The immersion sizing treatment is to impregnate the sizing agent. The unsizing base paper in the pulp is pressed and dried for the first time before entering the immersion sizing machine, so that the Beijing Lipu LP-301 sizing agent penetrates into the fiber and forms a barrier layer between the fibers. The sizing amount is controlled at 15-20g / m 2 , the paper acquires preliminary barrier functions of waterproofing, oil-proofing and enhanced flexibility.

[0017] Preferably, the sizing agent is composed of a fluorine-free oil-proofing agent and cassava starch, and the pH is 5.5 to 6.0. Further, the LP-301 sizing agent in this step is compounded with a fluorine-free oil-proofing agent LP-301 and cassava starch, and the concentration is 7.5 to 12.5%, the pH is 5.5 to 6.0, and the amount of the oil-proofing agent added is 3 to 5%.

[0018] Among them, the LP-301 fluorine-free oil-proof agent is a modified acrylate, modified by fluorine-free technology, with a light yellow transparent liquid appearance, PH 4-6, effective ingredients 15-18%, and density 1.0g / ml; it has the characteristics of high temperature resistance above 120°C, low dosage, no PFAS hazards, good water and oil resistance, and no need for sizing in the slurry, and meets food grade requirements.

[0019] The cassava starch boiling process preferably has a concentration of 7.5 to 12.5%; 3After adding water to 75% in the pot, pour in 75-125kg of modified starch and 100-150ml of starch invertase, heat to 80°C and keep warm for 20 minutes, then heat to 120°C and keep warm for 10 minutes to make a sizing compound with a viscosity of 20-25CPs. Put the obtained sizing compound into the feeding trough and add 3-5% LP-301 fluorine-free oil-proofing agent according to the process requirements to make a sizing compound auxiliary for immersion sizing. Preferably, the amount of the immersion sizing compound auxiliary is 15-20g / m 2 .

[0020] In an embodiment of the present invention, the paper after immersion sizing undergoes a second drying process, then enters a first surface coating process, then enters a third drying process, then undergoes a second surface coating process, a fourth drying process, and undergoes soft calendering, winding, rewinding and slitting to produce a plastic-free and aluminum-free high-barrier food packaging paper.

[0021] Preferably, the first surface coating and the second surface coating are both film transfer surface coating, and the coating amount of the first surface coating is 5-8 g / m 2 Further preferably, after the second surface coating, a fourth drying and calendering process is performed to obtain a high barrier food packaging paper product.

[0022] After impregnation with the sizing agent, the embodiment of the present invention uses Shanghai Xianke barrier material ZG-1 nanometer pure water-based narrow molecular weight acrylic copolyester for the first surface coating process, and the coating amount is preferably controlled at 6-10g / m 2 This nano-level pure water-based acrylic copolyester forms a second barrier on the paper surface, giving the paper higher waterproof, moisture-proof, oil-proof, oxygen-proof and flexibility effects.

[0023] Specifically, ZG~1 nanometer-level pure water-based narrow molecular weight acrylic copolyester is a pure water-based linear functional resin material with a special molecular structure. Its appearance color is off-white, the effective ingredient is 40±1.0%, and the viscosity is 200±50mPa·s. Its main characteristics are nanometer-level, narrow bandwidth and normal molecular weight distribution characteristics. It does not use solvent substances. Its linear main structure has environmentally friendly and harmless waterproof, oil-proof, moisture-proof, oxygen-barrier properties, process adaptability, and greatly reduces the use of additives. It has excellent microbial degradation performance while ensuring the stability of paper-based packaging materials.

[0024] In the embodiments of the present invention, the mechanism of action of the nano-scale water-based narrow molecular weight distribution acrylic copolyester includes: using the homopolymer structure of the functional groups inside the molecule plus its nano characteristics, utilizing the monodispersity and dispersibility-aiding functions of the linear functional copolyester, having chemical functionality and physical methods to enhance the adhesion to the fiber surface, forming self-crosslinking between acrylic copolyesters and co-crosslinking between acrylic copolyesters and fibers at the fiber interface, the self-crosslinking effect is that the acrylic copolyester produces an interlaced chain structure around the fiber, which limits the swelling of the fiber to a certain extent and increases the wet strength; the co-crosslinking effect is that the acrylic copolyester forms new bonds with some hydroxyl groups on adjacent fibers, especially the formation of a water-resistant covalent bond crosslinking network, which is the most critical for improving the waterproofness and increasing the strength of paper.

[0025] Then, the present invention uses Shanghai Xinke ZG-2 carbon chain block homopolymerized water-based acrylic copolyester polymer for surface coating, and the coating amount is controlled at 5.0-8.0 g / m 2 Its main purpose is to ensure that the paper has excellent waterproof, moisture-proof, oil-proof, oxygen-proof, acid- and alkali-resistant effects, while also obtaining excellent heat-sealing strength.

[0026] Furthermore, in the surface coating step, the water-based acrylic copolyester polymer of the homopolymerized ZG-2 carbon chain block is a pure water-based linear functional resin material with a special molecular structure, and its appearance color is milky white, the effective component is 38±1.0%, and the viscosity is 200±50mPa·s; its main characteristics are that it has a narrow band distribution of nanometer level and 0.5 narrow molecular weight, and the carbon chain block homopolymerization distribution is better than that of the ZG-1 nanometer pure water-based narrow molecular weight acrylic copolyester; it has chemical functionality and physical methods to improve the thermal bonding point with the fiber surface, and the co-crosslinking effect between the acrylic copolyester and the fiber is entangled into a film, and the solvent-free and quick-drying characteristics form a third barrier on the surface of the paper, thereby obtaining excellent waterproof, moisture-proof, oil-proof, and oxygen-proof barrier effects, and at the same time, the paper also obtains excellent heat sealing strength.

[0027] The preferred embodiment of the present invention selects the commercially available LP-301, ZG-1, and ZG-2 acrylic copolyesters, which are completely pure water-based and solvent-free system materials, have anti-hydrolysis and stable material properties, meet the storage cycle requirements, and preferably use microparticles of different particle sizes in the coating to increase the gas permeation resistance and achieve the high barrier goal; these food-grade, high-efficiency, high-barrier materials give paper excellent barrier functions.

[0028] The present invention preferably adopts a 1+2 dip coating and two film transfer coating arrangement for the barrier coating of the paper to meet the production processes of different grades of barrier materials, that is, no sizing is applied in the slurry, and a process combination of one sizing process as an immersion sizing process and two surface coating barrier materials is adopted. It can adapt to the barrier process technology of various combinations of different papers, base materials, and microparticle barrier materials to achieve plastic-free, fluorine-free, and aluminum-free environmentally friendly effects.

[0029] In order to ensure the barrier performance, strength and flexibility of the paper-based material, the glue-free base paper in the embodiment of the present invention first undergoes an immersion sizing process to give the paper preliminary waterproof, oil-proof, strengthening and toughening functions; then it undergoes a surface coating process and another surface coating process, and different types of metering rods are selected according to different barrier levels to control the film-forming property, upper liquid distribution and coating amount of the barrier material. The method is convenient, flexible and highly operable.

[0030] In addition, the advanced barrier layer density adjustment technology of the embodiment of the present invention utilizes the drying cylinder temperature in the papermaking machine and the pressure and temperature of the soft calendering equipment to increase the density of the barrier layer structure. The linear structure of the nano-level pure water-based narrow molecular weight acrylic copolyester has a two-dimensional nano-morphology. Under the action of temperature and pressure, the degree of entanglement of the molecules increases, which can increase the gas permeability resistance of the material.

[0031] The present invention provides a high barrier food packaging paper obtained by the manufacturing method as described above, wherein the product weight is 60 to 115 g / m 2 , further 100~115g / m 2 Preferably, the high barrier food packaging paper has an oxygen permeability of ≤3 gsm / 24h and a water vapor permeability of ≤5 gsm / 24h.

[0032] The paper material described in the embodiment of the present application is a high barrier packaging material with net zero quantitative VOCs, degradable and sustainable recycling, and has the characteristics of waterproof (30min, 23℃) ≤10gsm / 24h, oil resistance (23℃) ≥12kit, heat sealing strength (150-180℃) ≥2.6kN / m, oxygen permeability ≤3gsm / 24h, and water vapor permeability ≤5gsm / 24h. In addition, the whole production process has net zero quantitative VOCs emissions, and the product degradation recovery rate can reach more than 90%; the main barrier materials involved have nano-scale, narrow bandwidth and normal molecular weight distribution characteristics, do not use solvent substances, and their linear main structure has environmentally friendly waterproof, oil-proof, moisture-proof, oxygen-barrier properties, process adaptability, greatly reduced use of additives, and excellent microbial degradation performance. The embodiments of the present invention develop this plastic-free and aluminum-free high-barrier food packaging paper, which plays a positive role in solving the technical difficulties of high oxygen and water vapor permeability requirements for food packaging using paper instead of plastic, promoting environmentally friendly, green and recyclable development, leading industry trends, and enhancing corporate brand influence.

[0033] The product of the present invention belongs to a plastic-free and aluminum-free paper-based food packaging paper-based material, which can be used for packaging of various dried fruits, nuts, tea, dried meat, seasoning packaging such as coffee and ketchup, and food packaging bags such as bread. The paper has excellent functionality, strong adaptability, and is widely used in life. This plastic-free and aluminum-free high-barrier food packaging paper is a high-barrier plastic-replacing paper-based product with high technical content, strict quality requirements, and high production difficulty. It is used to replace PE or PE+PET or aluminum-plated PET composite packaging products to meet the indoor and outdoor storage stability of daily environments; the barrier material used in production is composed of carbon chain fiber and plant fiber, which can be recycled sustainably, with zero VOCs emissions in the entire production process, and is degradable, with a fiber repulp rate of more than 90%, good development prospects, and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The sheeting conditions of oil-proofing agent samples 1 to 3# in Example 1 of the present invention are shown;

[0035] Figure 2 This is the product situation of oil repellent samples 4 to 6# in Example 1 of the present invention;

[0036] Figure 3 These are the test results of the re-slurry performance of high barrier paper in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0038] In order to better understand the technical content of the present invention, the following specific examples are provided to further illustrate the present invention. In the following examples, unless otherwise specified, all are weight ratios; the raw materials used are commercially available and conventional equipment is used.

[0039] Among them, the fiber length of sulphate chemical softwood pulp is 2.35-2.6 mm, the width is 33.0-356.0 μm, the wet weight is 15-18 g, and the beating degree is 13-15.5°SR. The beating degree of chemical bamboo pulp is 12.5-15.0°SR, the wet weight is 10-13 g, the fiber length is 1.5-2.0 mm, and the width is 23.0-26.0 μm.

[0040] Example 1

[0041] (I) Experimental study on the effect of pulping aids on the mixed pulping of kraft chemical bamboo and wood pulp

[0042] 1. Purpose of the experiment

[0043] In order to meet the processing requirements of plastic-free and aluminum-free high-barrier food packaging paper for base paper, it is necessary to ensure that the chemical conifer pulp and chemical bamboo pulp have an appropriate beating degree, and at the same time pay attention to the length and strength of the fiber to meet the requirements of the base paper of plastic-free and aluminum-free high-barrier food packaging paper for tightness, air permeability and other properties. The application of YZ~01 beating aid and the influence of auxiliary beating and other technologies on the base paper of plastic-free and aluminum-free high-barrier food packaging paper were studied in detail.

[0044] 2. Experimental plan

[0045] 2.1 Fiber raw materials: kraft chemical coniferous pulp + 45% kraft chemical bamboo pulp, coniferous pulp beating degree 13.0°SR; chemical bamboo pulp, original pulp beating degree 14.5°SR.

[0046] 2.2 Pulping aid: YZ~01 mixed aid (mixed with cationic bio-enzyme and non-ionic hydroxypropyl guar gum in a weight ratio of 2:1, also known as composite aid YZ~01, etc.).

[0047] (1) The dosage of homemade bio-enzyme mixed additive YZ-01 is 0, 2.3, and 2.5 kg / t pulp;

[0048] (2) Enzyme treatment time: 2 h.

[0049] 2.3 Pulping equipment: PFI disc mill, the target beating degree is 45°SR; the mixed natural color chemical pulp is pulped through the PFI disc mill, and the pulping concentration is 10%.

[0050] 2.4 Sheet making: The beaten pulp is sheeted with a sheet making machine, and the sheet weight is 65g / m 2 , pressed and dried, and finally, constant temperature and humidity balance treatment was used to test relevant performance indicators.

[0051] 3. Experimental Results

[0052] Table 1 Physical indexes of composite additive YZ~01 pulping

[0053]

[0054] The experimental results of using the homemade composite beating additive YZ~01 to assist beating show that under the condition of fixed beating energy consumption (PFI beating revolution number 13000), the comprehensive improvement of the beating effect of the homemade composite beating additive YZ~01 to assist chemical bamboo-wood mixed pulp is more obvious; the beating degree can be significantly improved, and when the dosage is 2.3kg / t pulp, the strength indicators such as internal bonding strength and breaking length increase significantly; temperature is very important for the auxiliary beating effect of the homemade composite beating additive YZ~01. When the treatment temperature of the homemade composite beating additive YZ~01 is increased from 10℃ to 45℃, the auxiliary beating effect is greatly improved. When using the homemade composite beating additive YZ~01 to assist chemical bamboo-wood mixed pulp beating, its dosage should not be too high. It is recommended to control it within 3.0kg / t, otherwise it will cause the fiber strength to decrease, the cutting will be more obvious, and the pulp strength performance will be significantly reduced.

[0055] (II) Research on the application performance of waterproof and oil-proof barrier additives

[0056] 1. Research Objectives

[0057] In order to optimize the company's product structure, improve product quality and expand product market, the company actively promotes the development of food oil-proof paper, collects oil-proof agents from many companies and independently developed oil-proof agent products, and organizes forces to concentrate on oil-proof barrier experimental research in the laboratory.

[0058] 2. Raw materials

[0059] 1. Oil repellent:

[0060] (1) 1#: ZG-1, manufactured by Shanghai Xianke Chemical, is a pure water-based linear functional resin material, nanometer grade, molecular weight 1.0, normal molecular weight distribution, its appearance color is off-white, effective content 40±1.0%, viscosity 300±50mPa·s.

[0061] (2) 2#: ZG-2, manufactured by Shanghai Xianke Chemical, is a water-based acrylic copolyester polymer with nano-scale and narrow-band distribution characteristics of molecular weight 0.5. Its appearance color is milky white, the effective ingredient is 38±1.0%, and the viscosity is 200±50mPa·s.

[0062] (3) 3#: LP-301, manufactured by Beijing Lipufu Chemical, is a fluorine-free modified acrylate, with a light yellow transparent liquid appearance, pH 4-6, active ingredient 15-18%, and density 1.0 g / ml.

[0063] (4) 4#: NeoCryl A-2092, manufactured by Tishman of the Netherlands, is a water-based acrylic emulsion, with an active ingredient of 47.5±1%, high gloss, softness, water resistance, APEO-free, and in compliance with FDA and BGA standards. (5) 5#: BH-889, manufactured by Guangdong Bohai Chemical, a water-based resin, with an active ingredient of 30% to 40%, a viscosity of 15 to 25 mPa·s, a pH of 7 to 9, and excellent oil resistance, excellent film-forming properties, excellent anti-adhesion properties, and no plastic, fluorine, or silicone.

[0064] (6) 6#: BH885, manufactured by Guangdong Bohai Chemical, is a water-based acrylic emulsion with an active ingredient of 40±2%, a viscosity of 18±2 mPa·s, a pH of 7-8, and has high heat-sealing properties and good anti-adhesion characteristics.

[0065] 2. Base paper: 80g / m 2 Absorbent kraft paper, bursting index 3.0kpa.m 2 / g, longitudinal wet strength ≥1.0kN / m, water absorption 60-80g / m 2 , smoothness is about 10s.

[0066] Table 2 Basic properties of oil repellent

[0067]

[0068] 3. Experimental Methods

[0069] 1. Coating experiment: The oil-proof agent is coated on the base paper at different concentrations, infrared dried, calendered, and then placed in a constant temperature and humidity chamber for balance and testing.

[0070] 2. Disintegration experiment: Soak the paper sample and base paper coated with oil-proof agent in water respectively, and then disintegrate them at 4000 revolutions by the disintegration machine. Observe the disintegration situation and make sheets.

[0071] 3. Oil resistance test method: GB / T 22805.2-2008 Determination of fat resistance of paper and paperboard Part 2: Surface repulsion method is used to test the oil resistance of the sample. The test liquid is castor oil, toluene, and n-heptane, three analytical pure reagents, prepared in different proportions and with different Kit numbers. The main test steps are:

[0072] (1) Arrange the sample into a flat surface and do not touch the test surface with your hands;

[0073] (2) With the test surface facing upward, drop a drop of test liquid of the Kit number at a height of 25 mm;

[0074] (3) After 15 seconds, use clean toilet paper to remove the remaining test liquid;

[0075] (4) Immediately observe whether the back of the oil droplet changes color due to penetration;

[0076] (5) Repeat the test until the sample surface of the Kit number test liquid is not penetrated and changes color;

[0077] (6) The oil resistance of the sample is the Kit number.

[0078] 4. Experimental Results and Analysis

[0079] 1. Oil resistance grade and water absorption value

[0080] Table 3 Oil-proofing agent dosage and oil-proofing grade data

[0081]

[0082] 2. Results of fragmentation experiment

[0083] The fragmentation test results are shown in Figure 1 , Figure 2 , Figure 1 This is the sheet copying situation of oil repellent samples 1 to 3#. Figure 2 This is the product situation of oil repellent samples 4 to 6#. Figure 1 Sample preparation: Weigh a certain weight of coated paper, tear it into pieces, soak it in water for 10 minutes, completely dissociate the paper into single fibers in a fiber disintegrator, make sheets of the shredded pulp in a paper sheeter, and dry it to obtain recycled paper samples.

[0084] From the decomposition experiment, the decomposition of paper after adding oil-proof agent is close to that of base paper without oil-proof agent, and the amount of broken paper pieces has not increased significantly. Because the decomposition concentration in the laboratory is relatively low, the decomposition intensity is not as strong as that in the workshop, and the pulp after decomposition contains a certain amount of small paper pieces, which will not affect the recycling of broken paper after passing through the sieve and mill in the workshop.

[0085] 3. Ink absorbency

[0086] Table 4 Ink absorption results of oil-proofing agent samples

[0087]

[0088] From the paper ink absorbency experiment, we can see that as the oil-proof grade of the finished paper increases, the ink absorbency becomes worse. If printing is done on the oil-proof surface, the printing effect will be affected.

[0089] 4. Main conclusions

[0090] (1) When the coating amount is relatively close, 1# and 2# have the best oil-proof effect, followed by 3# and 4#, and 5# and 6# have the worst oil-proof effect.

[0091] (2) As the coating amount increases, the oil resistance level of the finished paper gradually increases, the water absorption decreases, and the air permeability decreases.

[0092] (3) The addition of oil-proof agent has no significant effect on paper shredding.

[0093] (4) As the oil-proof grade of the finished paper increases, the ink absorption becomes worse. If the oil-proof surface is used for printing, the printing effect will be affected.

[0094] (III) Experiment on the repulping rate of plastic-free and aluminum-free paper-based food packaging materials

[0095] 1. Purpose of experimental research:

[0096] Through laboratory degradation experiments on paper-based packaging materials coated with nano-scale water-based narrow molecular weight distribution acrylic copolyester, we evaluated whether its degradation and recyclability effects can meet relevant domestic and international standards.

[0097] 2. Experimental test methods:

[0098] Weigh a certain weight of coated paper, tear it into pieces, soak it in water for 10 minutes, completely dissociate the paper into single fibers in a fiber dissociator, make sheets of the dissociated pulp in a paper copyer, dry it, and obtain recycled paper samples. Weigh the paper samples re-copied after dissociation. The ratio of the weight of the copied paper sample to the weight of the paper before dissociation is used to obtain the recycling rate of paper fiber.

[0099] 3. Test results:

[0100] Table 5 Repulping rate experimental results

[0101]

[0102] From the analysis of test data, 95.9% recycled pulp was obtained after impregnation and coating of linear polymer material - nano-scale water-based narrow molecular weight distribution acrylic copolyester, and the dried linear polymer material and pulp fiber were regenerated and recycled at the same time after impregnation and coating, so that the strength of the fiber was not only not weakened but improved.

[0103] (IV) High barrier paper re-pulping performance test

[0104] 1. Purpose of the experiment

[0105] Test the repulp yield of paper pulp after coating with waterproof and oil-proof barrier materials to understand the degradability of the oil-proof agent.

[0106] 2. Determination Method

[0107] 1. Testing instruments:

[0108] Fiber disintegrator, stirrer, electric constant temperature drying oven, electronic balance, 70 mesh forming net.

[0109] 2. Test method:

[0110] The same as the pulp return rate measurement, but without the flat plate vibrating pulp screen and the round hole screen plate. Instead, the equivalent 0.7mm screen plate (filtered with a 70 mesh filter) is used.

[0111] 3. Test results:

[0112] A: White kraft paper: 96.8%;

[0113] B: Natural kraft paper: 96.3%.

[0114] 3. Determination of colloid and optical inhomogeneity

[0115] 1. Experimental instruments:

[0116] Fiber disintegrator, stirrer, electric constant temperature drying oven, electronic balance, thin steel plate, weights, ZY-CX Kaiser paper sheet former.

[0117] 2. Test method:

[0118] Same as the pulping rate determination, but without passing through the plate vibrating screen pulper.

[0119] 3. Test results:

[0120] Results Figure 3 Among them, A is white kraft paper, no adhesion effect, no damage after the paper is torn off, and no optical unevenness. B is natural kraft paper, no adhesion effect, no damage after the paper is torn off, and there is a lot of optical unevenness.

[0121] Example 2

[0122] The weight ratio of 55% sulfate coniferous wood chemical pulp and 45% sulfate chemical bamboo pulp is used. After mixing and crushing, YZ-01A composite pulping aid is added at 2.5kg / ton pulp in the pulp tank before beating with a metering pump to assist in beating. The beating concentration is 5.0%, the pulp beating degree is 46°SR, and the 0.35% dilute pulp is prepared. After screening and purification, it is put on the screen for papermaking. The paper weight is controlled at 75g / m 2 . Unsizing 75g / m 2 After the base paper is pressed and dried to 94% dryness in the first step, it enters the immersion sizing process. The sizing agent is a mixed liquid of LP-301 fluorine-free oil-proofing agent and cationic cassava starch. The concentration of cassava starch glue is 10%, the viscosity is 25CPs, the effective ingredient of LP-301 is 18%, and the sizing amount is 20g / m 2 .

[0123] After the immersion sizing paper is dried in the second stage, it enters the first stage of surface coating, then enters the third stage of drying, and then the second stage of surface coating, the fourth stage of drying, and soft calendering, winding and rewinding slitting to make 112g / m 2 Plastic-free and aluminum-free high barrier food packaging paper.

[0124] The first coating material is ZG~1 nanometer pure water-based narrow molecular weight acrylic copolyester, the effective component of acrylic copolyester is 40%, and the sizing coating amount is controlled at 10g / m 2 The second coating material is water-based acrylic copolyester with homopolymerization of ZG-2 carbon chain blocks. The effective content of water-based acrylic copolyester with homopolymerization of carbon chain blocks is 38%, and the sizing amount is controlled at 7.0g / m 2 .

[0125] Example 3

[0126] The weight ratio of 50% sulfate coniferous wood chemical pulp and 50% sulfate chemical bamboo pulp is used. After mixing and crushing, YZ-01A composite pulping aid is added at 3.0kg / ton pulp in the pulp pool before beating with a metering pump to assist in beating. The beating concentration is 5.0%, the pulp beating degree is 43°SR, and the 0.40% dilute pulp is prepared. After screening and purification, it is put on the screen for papermaking. The paper weight is controlled at 80g / m 2 . Unsizing 80g / m 2 After the base paper is pressed and dried to 94.5% dryness, it enters the immersion sizing process. The sizing material is a mixed liquid of LP-301 fluorine-free oil-proofing agent and cationic cassava starch. The concentration of cassava starch glue is 10%, the viscosity is 25CPs, the effective ingredient of LP-301 is 18%, and the sizing amount is 18g / m 2 .

[0127] After the immersion sizing paper is dried in the second stage, it enters the first stage of surface coating, then enters the third stage of drying, and then the second stage of surface coating, the fourth stage of drying, and soft calendering, winding and rewinding slitting, to make 115g / m 2 Plastic-free and aluminum-free high barrier food packaging paper.

[0128] The first coating material is ZG~1 nanometer pure water-based narrow molecular weight acrylic copolyester, the effective component of acrylic copolyester is 40%, and the sizing coating amount is controlled at 10g / m 2 The second coating material is water-based acrylic copolyester with homopolymerization of ZG-2 carbon chain blocks. The effective content of water-based acrylic copolyester with homopolymerization of carbon chain blocks is 38%, and the sizing amount is controlled at 7.5g / m 2 .

[0129] Example 4

[0130] The weight ratio of 52% sulfate coniferous wood chemical pulp and 43% sulfate chemical bamboo pulp is used. After mixing and crushing, YZ-01A composite pulping aid is added at 2.8kg / ton pulp in the pulp tank before beating with a metering pump to assist in beating. The beating concentration is 5.0%, the pulp beating degree is 45°SR, and the 0.35% dilute pulp is prepared. After screening and purification, it is put on the screen for papermaking. The paper weight is controlled at 70g / m 2 . Unsizing 70g / m 2 After the base paper is pressed and dried to 95.0% dryness, it enters the immersion sizing process. The sizing material is a mixed liquid of LP-301 fluorine-free oil-proofing agent and cationic cassava starch. The concentration of cassava starch glue is 12.5%, the viscosity is 23CPs, the effective ingredient of LP-301 is 18%, and the sizing amount is 20g / m 2 .

[0131] After the immersion sizing paper is dried in the second stage, it enters the first stage of surface coating, then enters the third stage of drying, and then the second stage of surface coating, the fourth stage of drying, and soft calendering, winding and rewinding slitting, to make 106g / m 2 Plastic-free and aluminum-free high barrier food packaging paper.

[0132] The first coating material is ZG~1 nanometer pure water-based narrow molecular weight acrylic copolyester, the effective component of acrylic copolyester is 40%, and the sizing coating amount is controlled at 8.0g / m 2 The second coating material is water-based acrylic copolyester with homopolymerization of ZG-2 carbon chain blocks. The effective content of water-based acrylic copolyester with homopolymerization of carbon chain blocks is 38%, and the sizing amount is controlled at 8.0g / m 2 .

[0133] The quality test results of the above three products are as follows:

[0134] Table 6 Product test results of Examples 2-4

[0135]

[0136] After testing, the above products comply with the national "Hygiene Standards for the Use of Additives in Food Containers and Packaging Materials" and the requirements of FDA and EU Food Contact Materials (FCM). In terms of degradation, they comply with EN13432, ASTMD6400, ISO17088 and national standard GB 28206.

[0137] From the above examples, it can be known that the method of the embodiment of the present invention uses 50-55% sulfate coniferous wood chemical pulp and 40-45% sulfate chemical bamboo pulp as fiber raw materials, and successively undergoes pulping, pulping, net forming, pressing, first drying, impregnation with sizing agent, second drying, first surface coating, third drying, and second surface coating to obtain high barrier food packaging paper; the first surface coating adopts nano-scale water-based acrylic copolyester material, and the second surface coating adopts water-based carbon chain block acrylic polymer material; the coating amount of the first surface coating is not less than the coating amount of the second surface coating. The food packaging paper described in the present invention has excellent barrier function and excellent mechanical properties, does not require plastic coating and aluminum plating, and is conducive to promoting environmentally friendly and recyclable development.

[0138] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0139] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A method for manufacturing plastic-free and aluminum-free high-barrier food packaging paper, characterized in that: The following steps are involved: According to the mass ratio, 50-55% of kraft softwood chemical pulp and 40-45% of kraft chemical bamboo pulp are used as fiber raw materials, and the high barrier food packaging paper is obtained by pulping, pulping, screen forming, pressing, first drying, impregnation with sizing agent, second drying, first surface coating, third drying, and second surface coating in sequence; The first surface coating is made of nano-scale water-based acrylic copolyester material with a room temperature viscosity of 150-250 mPa·s; the second surface coating is made of water-based carbon chain block acrylic polymer material; the coating amount of the first surface coating is not less than the coating amount of the second surface coating, and the coating amount of the second surface coating is 3-5 g / m 2 .

2. The manufacturing method according to claim 1, characterized in that: The beating degree of the kraft coniferous wood chemical pulp is 13-15.5°SR; the beating degree of the kraft chemical bamboo pulp is 12.5-15.0°SR.

3. The manufacturing method according to claim 1, characterized in that: The pulping is assisted by a biological enzyme mixed auxiliary agent, and the biological enzyme mixed auxiliary agent consists of a cationic biological enzyme and a non-ionic hydroxypropyl guar gum.

4. The manufacturing method according to claim 3, characterized in that: The mixed pulp of kraft coniferous wood chemical pulp and kraft chemical bamboo pulp has a pulping concentration of 4.5-5.5%, a beating degree of 42-48°SR, and a wet weight of 6.5-11.0 g.

5. The manufacturing method according to claim 1, characterized in that: The sizing agent is composed of a fluorine-free oil-proofing agent and cassava starch, and has a pH value of 5.5 to 6.

0.

6. The manufacturing method according to claim 5, characterized in that: The dosage of the impregnation sizing agent is 15-20 g / m 2 .

7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The first surface coating and the second surface coating are both film transfer surface coating, and the coating amount of the first surface coating is 5-8g / m 2 .

8. The manufacturing method according to claim 7, characterized in that: After the second surface coating, the fourth drying and calendering are performed to obtain a high barrier food packaging paper product.

9. The high barrier food packaging paper obtained by the manufacturing method according to any one of claims 1 to 8, wherein the product basis weight is 60 to 115 g / m 2 .

10. The high barrier food packaging paper according to claim 9, characterized in that: The high barrier food packaging paper has an oxygen permeability of ≤3gsm / 24h and a water vapor permeability of ≤5gsm / 24h.

Images