Composition for manufacturing barrier layer of paper pulp molded product, barrier layer, manufacturing method of barrier layer, material and paper container

Abstract

The invention discloses a composition for manufacturing a barrier layer of a paper pulp molded product, the barrier layer, a manufacturing method of the barrier layer, a material and a paper container. The composition comprises the following components in parts by weight: 30-50 parts of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheology modifier; 2 to 5 parts by weight of a dissolution promoter; 5 to 10 parts by weight of an auxiliary agent; 5 to 8 parts by weight of a sizing agent; and 70 to 100 parts by weight of water. According to the composition, by optimizing the formula, the stability and uniformity of polyhydroxyalkanoate coating liquid can be improved, the coating thickness of a barrier layer can be controlled by adjusting the content of polyhydroxyalkanoate in the formula of the composition, and the defects that an existing paper pulp molded product with the barrier property does not have environment-friendly degradability and cannot be degraded easily are overcome. And spraying, film covering or film spraying equipment needs to be additionally arranged, so that the defects of barrier property and the like are overcome.

Description

Technical Field

[0001] The present invention relates to the field of packaging materials, and specifically to a composition for manufacturing a barrier layer of pulp molding products, a barrier layer, a manufacturing method thereof, a material, and a paper container. Background Art

[0002] Pulp molding products are made by processing and blending plant fibers that can be fully recycled and reused into a slurry with a certain proportion and concentration. According to the product design and customized molds, they are formed by vacuum adsorption molding and use the principle of in-mold drying to form different types and uses of environmentally friendly paper products. However, ordinary pulp molding products do not have barrier properties and need to be additionally equipped with spraying, laminating, or coating equipment to make them have barrier properties.

[0003] Pulp molding products with barrier properties do not have environmental degradability, and the additional spraying, laminating, or coating processes are complex. The main problems existing in the current prior art are as follows: Pulp molding products cannot achieve the coating of a highly barrier biodegradable coating. Existing high-barrier formulations contain materials that are not food-contactable and non-degradable; existing pulp molding products do not have a highly barrier, degradable, and thickness-controllable coating. When using pulp molding to attach the barrier layer under the slurry suction process, the barrier property is poor, the thickness of the barrier layer is uncontrollable, and the coating is uneven. For example, CN117536025A discloses a production method of a paper-plastic container and a paper-plastic container, but the description of the adsorption of the barrier material in this patent document is relatively vague. The various materials added in the barrier material do not have the same physical properties and cannot be melt-molded at the molding temperature described in the patent, that is, the barrier material formulation does not match the barrier material described in the patent; the barrier material is stabilized using a chemical surfactant, with poor environmental friendliness, and vinyl acetate involved in the formulation in this patent is not a food-contactable material; it is impossible to control the thickness of the barrier layer. CN117050486A discloses a composition for manufacturing a barrier layer, a barrier layer, a manufacturing method thereof, and a packaging material. The barrier material polyalkylene carbonate in the composition formula of this patent document is non-degradable; the formation of the barrier layer requires secondary processing, and the molding method is hot-processing injection / extrusion molding. The extruded molten film cannot cover and adhere to a container with an irregular shape. CN116368188A discloses a PHA composition and a preparation method thereof. However, it should be noted that the application of PHA in this patent document does not conform to the actual situation. PHA cannot achieve a dense barrier layer without heating and melting. Therefore, it is very urgent and necessary to find a production method for a paper-plastic container with a highly barrier and degradable coating. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a composition for manufacturing a barrier layer of a pulp molding product, the barrier layer, its manufacturing method, materials, and paper containers, overcoming the defects that existing pulp molding products with barrier properties are not environmentally degradable and require additional laminating or coating equipment to have barrier properties.

[0005] A composition for manufacturing a barrier layer of a pulp molding product provided by the present invention includes:

[0006] 30 to 50 parts by weight of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheological modifier; 2 to 5 parts by weight of a solubilizer; 5 to 10 parts by weight of an auxiliary; 5 to 8 parts by weight of a sizing agent; 70 to 100 parts by weight of water.

[0007] Optionally, the particle size of the polyhydroxyalkanoate ≤ 10 microns.

[0008] Optionally, the rheological modifier includes any one or more of sodium alginate, carboxymethyl cellulose, and soy protein.

[0009] Optionally, the rheological modifier includes 0.1 to 1 part by weight of sodium alginate.

[0010] Optionally, the solubilizer includes any one or both of ethanol and isopropanol.

[0011] Optionally, the auxiliary includes an inorganic hybrid material, and the inorganic hybrid material includes any one or more of silica, diatomaceous earth, montmorillonite, and mica powder.

[0012] Optionally, the auxiliary includes 5 to 8 parts by weight of mica powder.

[0013] Optionally, the sizing agent is a rosin sizing agent.

[0014] In addition, the present invention also provides a barrier layer for a pulp molding product, and the barrier layer is made of the above-mentioned composition for manufacturing a barrier layer of a pulp molding product.

[0015] In addition, the present invention also provides a manufacturing method for a barrier layer of a pulp molding product, which is used to manufacture the above-mentioned barrier layer of a pulp molding product, and the manufacturing method includes:

[0016] Mix polyhydroxyalkanoate, a rheological modifier, a solubilizer, an auxiliary, a sizing agent, and water to obtain a polyhydroxyalkanoate emulsion;

[0017] Absorb pulp by a suction process to process a wet blank;

[0018] The pulp in the wet blank state is extruded, sprayed with the polyhydroxyalkanoate emulsion, and hot-pressed to form a uniform barrier layer on the surface of the pulp molding.

[0019] Optionally, the process of extruding the pulp in the wet blank state, spraying the polyhydroxyalkanoate emulsion, and hot-pressing to form a uniform barrier layer on the surface of the pulp molding includes:

[0020] Spray the polyhydroxyalkanoate emulsion on the pulp in the wet blank state. Place the inner cavity of the pulp attached with the polyhydroxyalkanoate emulsion into an elastomer bag. The elastomer bag is inflated by high temperature to dry the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion. The preset values are a thermoforming temperature of 145°C to 150°C, a drying time of 3 minutes, and an inflation pressure of the elastomer bag of 0.1 MPa to 1 MPa.

[0021] After drying the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion, the elastomer bag and the thermoforming mold apply pressure respectively, and the pressure value is 5.0 MPa to 10.0 MPa, so that the polyhydroxyalkanoate attached to the pulp melts, and a uniform barrier layer is formed on the surface of the pulp molding.

[0022] The present invention also provides a pulp molding material, which includes: the barrier layer for pulp molding products described above.

[0023] The present invention also provides a paper container, which includes: the barrier layer for pulp molding products described above.

[0024] Compared with the prior art, the composition, barrier layer, manufacturing method, material, and paper container for manufacturing the barrier layer of pulp molding products provided by the embodiments of the present invention have the following advantages:

[0025] The composition for manufacturing the barrier layer of pulp molding products provided by the embodiments of the present invention includes 30 to 50 parts by weight of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheological modifier; 2 to 5 parts by weight of a co-solvent; 5 to 10 parts by weight of an auxiliary agent; 5 to 8 parts by weight of a sizing agent; and 70 to 100 parts by weight of water. By optimizing the formula, the composition can improve the stability and uniformity of the polyhydroxyalkanoate coating solution, and the thickness of the barrier layer coating can be controlled by adjusting the content of polyhydroxyalkanoate in the composition formula.

[0026] The embodiments of the present invention also provide a barrier layer for pulp molding products. The barrier layer is made of the composition for manufacturing the barrier layer of pulp molding products. The barrier layer is dense, has good water resistance and oil resistance, and the coating closely adheres to the container and is not easy to peel off.

[0027] An embodiment of the present invention also provides a manufacturing method for a barrier layer of a pulp molding product. The process of the barrier layer is simple, can be integrally formed, and its thickness can be uniformly controlled, effectively controlling the production cost.

[0028] An embodiment of the present invention also provides a pulp molding material, which includes the barrier layer described in the embodiment of the present invention, and the material is environmentally friendly and degradable.

[0029] An embodiment of the present invention also provides a paper container, which includes the barrier layer described in the embodiment of the present invention, and the paper container has good barrier properties and is environmentally friendly and degradable. Description of the Drawings

[0030] Figure 1 It is a process flow chart for manufacturing the barrier layer of the pulp molding product in the embodiment of the present invention.

[0031] Figure 2 It is an electron microscope photograph of the cross-section of the high-barrier pulp molding product prepared in Embodiment 1 of the present invention and the commercially available high-barrier product with a coated film. Detailed Embodiments

[0032] As described in the background art, currently, the existing pulp molding products with barrier properties are not environmentally friendly and degradable, and additional spraying, laminating, or coating equipment is required to endow them with barrier properties. The main problems existing in the current prior art are as follows: The pulp molding products cannot achieve the coating of a highly barrier bio-degradable coating, and the existing high-barrier formulations contain materials that are not food-contactable and non-degradable; the existing pulp molding products do not have a highly barrier, degradable, and thickness-controllable coating. When the barrier layer is attached by the pulp molding in the slurry absorption process, the barrier property is poor, the thickness of the barrier layer is uncontrollable, and the coating is uneven.

[0033] To solve the above technical problems, the composition for manufacturing the barrier layer of the pulp molding product provided by the embodiment of the present invention includes 30 to 50 parts by weight of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheological modifier; 2 to 5 parts by weight of a co-solvent; 5 to 10 parts by weight of an auxiliary agent; 5 to 8 parts by weight of a sizing agent; and 70 to 100 parts by weight of water. By optimizing the formula, the composition can improve the stability and uniformity of the polyhydroxyalkanoate coating solution, and the thickness of the barrier layer coating can be controlled by adjusting the content of polyhydroxyalkanoate in the composition formula.

[0034] An embodiment of the present invention also provides a barrier layer for a pulp molding product, which is made of the composition for manufacturing the barrier layer of the pulp molding product. The barrier layer is dense, has good water resistance and oil resistance, and the coating closely adheres to the container and is not easy to peel off.

[0035] An embodiment of the present invention also provides a method for manufacturing a barrier layer of a pulp molding product. The process of the barrier layer is simple, can be integrally formed, and its thickness can be uniformly controlled, effectively controlling the production cost.

[0036] An embodiment of the present invention also provides a pulp molding material, which includes the barrier layer described in the embodiment of the present invention, and the material is environmentally friendly and degradable.

[0037] An embodiment of the present invention also provides a paper container, which includes the barrier layer described in the embodiment of the present invention, and the paper container has good barrier properties and is environmentally friendly and degradable.

[0038] In the embodiment of the present invention, the raw materials, equipment, etc. used in the preparation process of the barrier layer are all commercially available products and can be purchased in the market.

[0039] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] In addition, a composition for manufacturing a barrier layer of a pulp molding product provided by an embodiment of the present invention includes:

[0041] 30 to 50 parts by weight of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheological modifier; 2 to 5 parts by weight of a cosolvent; 5 to 10 parts by weight of an auxiliary agent; 5 to 8 parts by weight of a sizing agent; 70 to 100 parts by weight of water. By optimizing the formula, combining the rheological modifier, cosolvent, auxiliary agent, sizing agent with polyhydroxyalkanoate, a more stable polyhydroxyalkanoate solution (no stratification at room temperature within 48 hours) can be obtained subsequently, thereby improving the stability and uniformity of the polyhydroxyalkanoate coating solution, and the thickness of the barrier layer coating can be controlled by adjusting the content of polyhydroxyalkanoate in the composition formula.

[0042] Specifically, the addition of the rheological modifier can change the rheology of the polyhydroxyalkanoate emulsion, that is, the viscosity; the cosolvent can change the overall polarity and zeta potential of the polyhydroxyalkanoate emulsion; the auxiliary agent can make the polyhydroxyalkanoate emulsion have better dispersibility; the sizing agent can increase the adhesion of the polyhydroxyalkanoate emulsion to the pulp molding product and the barrier property of the coating.

[0043] Optionally, in some embodiments, the particle size of the polyhydroxyalkanoate ≤ 10 microns. It should be noted that too large a particle size of the polyhydroxyalkanoate will cause microscopically unevenness during subsequent hot pressing, affecting the quality of the barrier layer of the pulp molding product.

[0044] Optionally, in some embodiments, the rheological modifier includes any one or more of sodium alginate, carboxymethyl cellulose, and soy protein.

[0045] Optionally, in some embodiments, the rheological modifier comprises 0.1 to 1 part by weight of sodium alginate. It should be noted that, according to actual production needs and based on the thickness requirements of the barrier layer, the composition and ratio of the rheological modifier can be adjusted according to the system viscosity. When the viscosity is high, the solid content of polyhydroxyalkanoate in the polyhydroxyalkanoate emulsion is relatively high, and the thickness of the barrier layer is also relatively high.

[0046] Furthermore, a single rheological modifier or a combination of multiple rheological modifiers can be selected, or the rheological modifier can be compounded with a solution containing metal ions. Specifically, in one embodiment, sodium alginate can be selected to be compounded with a metal ion solution, and the two can produce an irreversible cross-linking effect. The cross-linking network can fix the distribution state of the polyhydroxyalkanoate powder in the solution and increase the dispersion stability of the polyhydroxyalkanoate powder in the solution system. Secondly, the compounding of two or more rheological modifiers can increase the mechanical properties of the coating solution after film formation, effectively increasing the breaking strength and elongation at break.

[0047] Optionally, in some embodiments, the solubilizer comprises any one or both of ethanol and isopropanol. For example, in one embodiment, the solubilizer is isopropanol.

[0048] Optionally, in some embodiments, the auxiliary agent comprises an inorganic hybrid material, and the inorganic hybrid material comprises any one or more of silica, diatomite, montmorillonite, and mica powder.

[0049] Optionally, in some embodiments, the auxiliary agent comprises 5 to 8 parts by weight of mica powder.

[0050] Optionally, in some embodiments, the sizing agent is a rosin sizing agent.

[0051] In addition, an embodiment of the present invention further provides a barrier layer for a pulp molding product, and the barrier layer is made of the composition for manufacturing the barrier layer of the pulp molding product described above. The barrier layer made of the composition for manufacturing the barrier layer of the pulp molding product according to the embodiment of the present invention is dense, has good water resistance and oil resistance, and the coating closely adheres to the container and is not easy to peel off.

[0052] Please refer to Figure 1 , Figure 1 which is the process flow chart of the barrier layer of the pulp molding product in the embodiment of the present invention. The manufacturing method of the barrier layer of the pulp molding product provided by the embodiment of the present invention is used to manufacture the barrier layer of the pulp molding product described above, and the manufacturing method includes:

[0053] S100, mixing polyhydroxyalkanoate, a rheological modifier, a solubilizer, an auxiliary agent, a sizing agent, and water to obtain a polyhydroxyalkanoate emulsion;

[0054] S200, The pulp is adsorbed by the pulp absorption process to obtain a wet blank;

[0055] S300, The pulp in the wet blank state is extruded, sprayed with the polyhydroxyalkanoate emulsion, and hot-pressed to form a uniform barrier layer on the surface of the pulp molding.

[0056] Specifically, in some embodiments, the process of extruding the pulp in the wet blank state, spraying the polyhydroxyalkanoate emulsion, and hot-pressing to form a uniform barrier layer on the surface of the pulp molding includes:

[0057] The pulp in the wet blank state is sprayed with the polyhydroxyalkanoate emulsion. The inner cavity of the pulp attached with the polyhydroxyalkanoate emulsion is placed in an elastomer bag. The elastomer bag is inflated by high temperature to dry the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion. The preset values are a thermoforming temperature of 145°C to 150°C, a drying time of 3 min, and an inflation pressure of the elastomer bag of 0.1 MPa to 1 MPa;

[0058] After drying the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion, the elastomer bag and the thermoforming mold apply pressure respectively, and the pressure value is 5.0 MPa to 10.0 MPa, so that the polyhydroxyalkanoate attached to the pulp melts, and a uniform barrier layer is formed on the surface of the pulp molding.

[0059] The embodiment of the present invention also provides a manufacturing method of a barrier layer. The process of the barrier layer is simple, can be integrally formed, and its thickness can be uniformly controlled, which can effectively control the production cost.

[0060] It should be noted that the manufacturing method of the barrier layer provided by the embodiment of the present invention can achieve uniform and controllable thickness of the barrier layer of the special-shaped container by optimizing the polyhydroxyalkanoate coating liquid formula and the temperature and pressure of the inner cavity elastomer bag. Specifically, due to the certain viscosity and film-forming property of the polyhydroxyalkanoate emulsion, a film with polyhydroxyalkanoate particles will be quickly formed on the surface of the special-shaped container. When a thicker film is required, it can be achieved only by increasing the solid content of the polyhydroxyalkanoate in the emulsion; after spraying and drying to form a film, the polyhydroxyalkanoate particles can be evenly distributed on the special-shaped container, and then the polyhydroxyalkanoate particles are melted by the thermoforming mold. At this time, a polymer film can be formed in the molten state. Therefore, a biodegradable high-barrier pulp molding product can be obtained by one-time molding through this method, without separately purchasing spraying, laminating or coating equipment, and can be applied to the molding of biodegradable pulp molding products of different sizes and shapes. The finished barrier layer is dense, has good water resistance and oil resistance, and the coating is closely attached to the container and is not easy to peel off.

[0061] An embodiment of the present invention also provides a pulp molding material, which includes the barrier layer for pulp molding products described in the embodiment of the present invention, and the material is environmentally friendly and degradable.

[0062] An embodiment of the present invention also provides a paper container, which includes the barrier layer described in the embodiment of the present invention, and the paper container has good barrier properties and is environmentally friendly and degradable.

[0063] Example 1

[0064] 1. Formula

[0065] Formula of polyhydroxyalkanoate emulsion:

[0066] 50 g of polyhydroxyalkanoate, and the particle size of the polyhydroxyalkanoate is ≤10 microns;

[0067] Rheological modifier: 5 g of sodium alginate;

[0068] Solubilizer: 5 g of ethanol;

[0069] Auxiliary agent: 5 g of silica;

[0070] Sizing agent: 5 g of rosin sizing agent;

[0071] 100 g of water.

[0072] 2. Equipment

[0073] The paper-plastic mold includes a pulp suction, extrusion, spraying, and hot pressing mold.

[0074] The pulp suction mold is consistent with the shape of the forming container and is used to initially form a wet blank by evacuating after injecting pulp; the extrusion mold extrudes through an elastomer bag to form a preformed paper container; the polyhydroxyalkanoate emulsion is sprayed through a spraying device, and finally the hot pressing mold pressurizes the preformed paper container by filling high-pressure gas, water pressure or oil pressure, etc. to play a role in draining water and melting the polyhydroxyalkanoate barrier layer, so as to ensure the formation of a high-barrier degradable pulp molding.

[0075] 3. Preparation method

[0076] (1) 5 g of sodium alginate is added to 100 g of water and stirred and swollen at 45°C for 2 h to ensure that the sodium alginate is completely dissolved, obtaining a sodium alginate solution.

[0077] (2) 50 g of polyhydroxyalkanoate is added to the sodium alginate solution, and is fully dispersed through a homogenizing device. 5 g of ethanol is added to improve the dispersion and hydration efficiency. After ensuring that the polyhydroxyalkanoate is evenly dispersed without agglomeration, 5 g of silica and 5 g of rosin sizing agent are added to improve the stability and uniformity of the subsequent coating formula. After stirring for 30 min, the solution is left to stand to defoam, obtaining a pulp molding barrier layer solution.

[0078] (3) The pulp is adsorbed by the suction process, and the pulp molding machine is started to process it into a three-dimensional paper plastic product to obtain a wet blank.

[0079] (4) The pulp in the wet blank state is attached with the barrier layer material by spraying the pulp molding barrier layer solution. The inner cavity (the side with the barrier material) of the pulp attached with the barrier material is placed in an elastomer bag. The elastomer bag inflates and dries the moisture in the pulp molding wet blank and the barrier layer through high temperature. The preset values are a thermoforming temperature of 150 °C, a drying time of 3 min, and an inflation pressure of the elastomer bag of 1.0 MPa.

[0080] (5) After drying the pulp molding wet blank and the barrier layer, the second round of the elastomer bag and the thermoforming mold apply pressure respectively, and the pressure value is 10.0 MPa, so that the polyhydroxyalkanoate in the pulp molding barrier layer melts, and a uniform barrier layer is formed on the surface of the pulp molding.

[0081] Example 2

[0082] 1. Formula

[0083] Polyhydroxyalkanoate emulsion formula:

[0084] 50 g of polyhydroxyalkanoate, and the particle size of the polyhydroxyalkanoate ≤ 10 microns;

[0085] Rheological modifier: 10 g of carboxymethyl cellulose;

[0086] Promoter: 5 g of isopropanol;

[0087] Auxiliary agent: 5 g of diatomite;

[0088] Sizing agent: 5 g of rosin sizing agent;

[0089] 100 g of water.

[0090] 2. Equipment

[0091] The same as in Example 1, which will not be elaborated here.

[0092] 3. Preparation method

[0093] (1) 10 g of carboxymethyl cellulose is added to 100 g of water, and stirred and swollen at 45 °C for 2 h to ensure that the carboxymethyl cellulose is completely dissolved, obtaining a carboxymethyl cellulose solution.

[0094] (2) Add 50 g of polyhydroxyalkanoate to the carboxymethyl cellulose solution, disperse it thoroughly through a homogenizing device, add 5 g of isopropanol to improve the dispersion and hydration efficiency. After ensuring that the polyhydroxyalkanoate is evenly dispersed without agglomeration, add 5 g of diatomaceous earth and 5 g of rosin sizing agent to improve the stability and uniformity of the subsequent coating formulation. After stirring for 30 min, let the solution stand to defoam, and obtain the pulp molding barrier layer solution.

[0095] (3) Adsorb the pulp by the suction process, and turn on the pulp molding machine to process it into a three-dimensional paper-plastic product to obtain a wet blank.

[0096] (4) Attach the barrier layer material by spraying the pulp molding barrier layer solution in the wet state of the pulp blank. Put the inner cavity (the side with the barrier material) of the pulp wet blank with the attached barrier material into the elastomer bag. The elastomer bag inflates and dries the water in the pulp molding wet blank and the barrier layer through high temperature. The preset values are a thermoforming temperature of 150 °C, a drying time of 3 min, and an inflation pressure of the elastomer bag of 1.0 MPa.

[0097] (5) After drying the pulp molding wet blank and the barrier layer, apply pressure to the elastomer bag and the thermoforming mold respectively for the second time, and the pressure value is 10.0 MPa, so that the polyhydroxyalkanoate in the pulp molding barrier layer melts, and a uniform barrier layer is formed on the surface of the pulp molding.

[0098] Example 3

[0099] 1. Formula

[0100] Polyhydroxyalkanoate emulsion formula:

[0101] 50 g of polyhydroxyalkanoate, and the particle size of the polyhydroxyalkanoate ≤ 10 microns;

[0102] Rheology modifier: 5 g of soy protein;

[0103] Promoter: 5 g of ethanol;

[0104] Auxiliary agent: 5 g of mica powder;

[0105] Sizing agent: 5 g of rosin sizing agent;

[0106] 100 g of water.

[0107] 2. Equipment

[0108] The same as in Example 1, which will not be elaborated here.

[0109] 3. Preparation method

[0110] (1) Add 5 g of soy protein to 100 g of water, stir and swell at 45 °C for 2 h to ensure that the soy protein is completely dissolved, and obtain the soy protein isolate solution.

[0111] (2) Add 50 g of polyhydroxy fatty acid ester to the soy protein isolate solution, and disperse it thoroughly through a homogenization device. Then add 5 g of ethanol to improve the dispersion and hydration efficiency. After ensuring that the polyhydroxy fatty acid ester is evenly dispersed without agglomeration, add 5 g of mica powder and 5 g of rosin sizing agent to improve the stability and uniformity of the subsequent coating formulation. After stirring for 30 min, let the solution stand to defoam, and obtain the pulp molding barrier layer solution.

[0112] (3) The pulp is adsorbed by the suction process, and the pulp molding machine is started to process it into a three-dimensional paper-plastic product to obtain a wet blank.

[0113] (4) Attach the barrier layer material to the wet pulp blank in the wet blank state by spraying the pulp molding barrier layer solution. Put the inner cavity (the side with the barrier material) of the pulp wet blank with the attached barrier material into an elastomer bag. The elastomer bag inflates at high temperature to dry the moisture in the pulp molding wet blank and the barrier layer. The preset values are a thermoforming temperature of 150 °C, a drying time of 3 min, and an inflation pressure of the elastomer bag of 1.0 MPa.

[0114] (5) After drying the pulp molding wet blank and the barrier layer, the elastomer bag and the thermoforming mold apply pressure respectively in the second round, and the pressure value is 10.0 MPa, so that the polyhydroxy fatty acid ester in the pulp molding barrier layer melts, and a uniform barrier layer is formed on the surface of the pulp molding.

[0115] Next, by comparing the product performance of the high-barrier pulp molding products prepared in Examples 1 to 3 of the present invention with commercially available products, the advantages of the barrier layer and its preparation method of the present invention for pulp molding products are further illustrated. The results are shown in Table 1.

[0116] Sample:

[0117] Commercially available ordinary pulp molding product: namely, a plastic-free coated foam cup. This plastic-free coated foam cup is an environmentally friendly packaging material. It uses an aqueous coating to replace the polyethylene coating in traditional paper cups, achieving full biodegradation.

[0118] Specifications of the commercially available coated pulp molding product: 20 OZ, and the product name is a plastic-free aqueous coated paper cup.

[0119] Prepare pulp molding products according to the formulations and preparation methods of Examples 1 to 3. During the continuous production process, take 10 samples from the finished products of each example to detect the barrier layer thickness and barrier properties. The test methods and results are as follows:

[0120] According to GB / T 451.3-2002 Determination of the Thickness of Paper and Board, the thickness of the specimen is tested.

[0121] According to GB / T 451.2-2002 Determination of the Grammage of Paper and Board, the grammage of the specimen is tested.

[0122] According to GB / T 1540 Paper and board - Determination of water absorbency (Cobb method), the Cobb value test was carried out on the test specimens.

[0123] According to GB / T 22805.2 - 2002 Paper and board - Determination of grease resistance - Part 2: Surface exclusion method, the oil resistance grade test (KIT value) was carried out on the test specimens.

[0124] Table 1 Performance test results of commercially available molded products and molded products of Examples 1 to 3

[0125]

[0126] It can be seen from the results in Table 1 that compared with the barrier properties of commercially available molded products, the pulp molded products of the degradable high - barrier material prepared by the present invention have good oil and water resistance (obtained according to the test results of Cobb value and Kit), and the formulated coating solutions are all degradable environmental protection materials, which are more environmentally friendly.

[0127] In addition, as Figure 2 shown, by comparing the high - barrier pulp molded product prepared in Example 1 of the present invention with the commercially available high - barrier product with a laminated film under an electron microscope, it was found that the high - barrier coating prepared in Example 1 of the present invention is tightly connected to the paper base, without obvious gaps and is not easy to peel; while for the high - barrier product with a laminated film, the high - barrier layer formed by the laminated film is not tightly connected to the paper base, with obvious cracks and is easy to peel.

[0128] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A composition for manufacturing a barrier layer of a pulp molding product, characterized in that, Comprising: 30 to 50 parts by weight of polyhydroxyalkanoate; 0.1 to 10 parts by weight of a rheological modifier; 2 to 5 parts by weight of a solubilizer; 5 to 10 parts by weight of an auxiliary agent; 5 to 8 parts by weight of a sizing agent; 70 to 100 parts by weight of water.

2. The composition for manufacturing a barrier layer of a pulp molded product according to claim 1, characterized in that, The particle size of the polyhydroxyalkanoate is ≤ 10 microns.

3. The composition for manufacturing a barrier layer of a pulp molded product according to claim 1, characterized in that, The rheological modifier includes any one or more of sodium alginate, carboxymethyl cellulose, and soy protein.

4. The composition for manufacturing a barrier layer of a pulp molding product according to claim 3, characterized in that, The rheological modifier includes 0.1 to 1 part by weight of sodium alginate.

5. The composition for manufacturing a barrier layer of a pulp molding product according to claim 1, characterized in that, The solubilizer includes any one or both of ethanol and isopropanol.

6. The composition for manufacturing a barrier layer of a pulp molding product according to claim 1, characterized in that, The auxiliary agent includes an inorganic hybrid material, and the inorganic hybrid material includes any one or more of silica, diatomaceous earth, montmorillonite, and mica powder.

7. The composition for manufacturing a barrier layer of a pulp molding product according to claim 6, characterized in that, The auxiliary agent includes 5 to 8 parts by weight of mica powder.

8. The composition for manufacturing a barrier layer of a pulp molding product according to claim 1, characterized in that, The sizing agent is a rosin sizing agent.

9. A barrier layer for pulp molding products, characterized in that, The barrier layer is made of the composition for manufacturing the barrier layer of the pulp molding product according to any one of claims 1 to 8.

10. A manufacturing method for a barrier layer of a pulp molding product, characterized in that, For manufacturing the barrier layer of the pulp molding product according to claim 9, the manufacturing method includes: Mixing polyhydroxyalkanoate, a rheological modifier, a solubilizer, an auxiliary agent, a sizing agent, and water to obtain a polyhydroxyalkanoate emulsion; Adsorbing pulp by a suction pulp process to obtain a wet blank; Extruding the pulp in the wet blank state, spraying the polyhydroxyalkanoate emulsion, and hot pressing to form a uniform barrier layer on the surface of the pulp molding.

11. The manufacturing method of the barrier layer of the pulp molding product according to claim 10, characterized in that, The step of extruding the pulp in the wet blank state, spraying the polyhydroxyalkanoate emulsion, and hot pressing to form a uniform barrier layer on the surface of the pulp molding includes: Spraying the polyhydroxyalkanoate emulsion on the pulp in the wet blank state, putting the inner cavity of the pulp attached with the polyhydroxyalkanoate emulsion into an elastomer bag, and the elastomer bag is inflated by high temperature to dry the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion. The preset values are a thermoforming temperature of 145°C to 150°C, a drying time of 3 min, and an inflation pressure of the elastomer bag of 0.1 MPa to 1 MPa; After drying the moisture in the pulp molding wet blank and the polyhydroxyalkanoate emulsion, the elastomer bag and the thermoforming mold apply pressure respectively, and the pressure value is 5.0 MPa to 10.0 MPa to melt the polyhydroxyalkanoate attached to the pulp and form a uniform barrier layer on the surface of the pulp molding.

12. A pulp molding material, characterized in that, Comprising: The barrier layer for pulp molding products according to claim 9.

13. A paper container, characterized in that, Comprising: The barrier layer for pulp molding products according to claim 9.

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