Hemp stem core powder slurry composition and use thereof

Abstract

This invention provides a hemp stalk core powder slurry composition and its application. The composition comprises, by weight, 70-90 parts hemp stalk core powder, 2-10 parts softener, 2-10 parts reinforcing agent, 1-10 parts adhesive, 0-10 parts calcium carbonate, 0-1.0 parts defoamer, and 0-0.5 parts dispersant; the hemp stalk core is composed of 100-200 mesh particles. This invention provides a hemp stalk core powder slurry composition. The slurry formed by this composition can be directly used as the main material for coatings and laminated with base paper to produce packaging paper, especially specialty packaging paper. No modification of the hemp stalk core powder is required to achieve good performance and environmental friendliness in the obtained specialty packaging paper. Furthermore, the production process of specialty packaging paper is simple and easy to operate, with no powder loss, low pollution, reduced difficulty in treating papermaking wastewater, high efficiency, low cost, and advantages in market promotion.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, specifically to hemp stalk core powder slurry composition and its application. Background Technology

[0002] Hemp (China hemp), also known as fire hemp, cold hemp, etc., belongs to the genus Cannabis in the family Moraceae. Industrial hemp refers to artificially selected hemp varieties whose tetrahydrocannabinol (THC) content in the top leaves and flower spikes during the flowering period is <0.3% (dry matter percentage), thus losing their value for extracting drugs and direct use as narcotics. Research on the industrialization of hemp in my country can be traced back to the 1970s. With changes in people's lifestyles, advancements in industrial hemp technology, and the development of application scenarios, the industrial hemp industry has experienced rapid growth. According to New Frontier Data, the global hemp market size was approximately US$29.4 billion in 2020, and is projected to increase to US$58.7 billion by 2024.

[0003] China has begun to develop a comprehensive hemp industry chain, issuing corresponding guidance policies or authorization licenses for each stage, from breeding and planting to processing and application. In 2017, Heilongjiang Province amended its "Anti-Drug Regulations," clearly distinguishing between "industrial hemp" and "drug hemp," allowing the cultivation of industrial hemp and imposing special management on its planting, processing, and sales. On February 9, 2018, the General Office of the Heilongjiang Provincial People's Government issued the "Three-Year Special Action Plan for the Heilongjiang Province Hemp Industry," vigorously promoting the development of industrial hemp cultivation and forming the largest industrial hemp raw material production area in China in terms of planting area, output, and quality. The province is determined to build Heilongjiang Province into the largest industrial hemp industry base in China and even globally, gradually forming a comprehensive industrial hemp development industry chain. The industrial hemp industry is one of the key development directions for Heilongjiang Province.

[0004] Industrial hemp is simple to cultivate, labor-saving, and time-saving, and can be grown throughout my country, especially suitable for hillsides, wastelands, and saline-alkali land, without competing with grain, cotton, or oil crops for land. Industrial hemp also features fewer pests and diseases, resistance to natural disasters and weeds, and a short growth cycle, making it particularly suitable for crop rotation and intercropping. Furthermore, industrial hemp has high biomass yield; the yield of one season's stalks is equivalent to that of a year's fast-growing forest; its bast fiber yield can reach over 100 kg / mu, higher than flax. Therefore, industrial hemp is a high-yield and high-efficiency economic crop. According to the *China Agricultural Statistical Yearbook* and statistics from the Food and Agriculture Organization of the United Nations, my country accounts for 50% of the world's industrial hemp cultivation area.

[0005] Hemp fiber, seeds, flowers, and leaves have a wide range of applications and high economic value. Hemp fiber has advantages such as antibacterial properties, breathability, quick-drying, and UV protection, and can be used in textiles or as a reinforcing material in building materials, automobiles, and aerospace materials. Hemp seed oil extracted from its seeds can be used in cosmetics and health products; cannabinoids extracted from its flowers and leaves can provide biopharmaceutical raw materials for various diseases such as epilepsy, depression, Parkinson's disease, and cancer; hemp stalks account for about 60% to 70% of the total weight of hemp stalks, and their comprehensive utilization is one of the main research contents of hemp projects. How to make good use of stalks and reduce waste of raw materials and environmental pollution has attracted much attention in the industry. Currently, it is mainly used to make building boards and biomass fuel, but the sales volume is affected to some extent because the boards produced are not cost-competitive. Biomass fuel requires specific environments for use and has high transportation costs. Therefore, how to improve the economic value of stalks and expand their application fields is one of the key points of existing industrial hemp research. Currently, some research institutes and universities have conducted research and development on the preparation of new composite materials using stalks. The patents and research papers involved include: Chinese Patent CN202110277187.X: A method for preparing modified hemp stalk core powder composite material; Chinese Patent CN202010165197.X: A waterborne UV-curable coating modified with hemp stalk core powder and its preparation method and application; Chinese Patent CN202210575252.1: A method for preparing antibacterial pulp board and carbon-loaded mulch film paper using hemp stalk core, corn cob and rice straw; Chinese Patent CN202211303323.9: A modified hemp stalk core powder and reinforced polypropylene composite material and its preparation method.

[0006] Related research papers: Preparation and study of structure and properties of hemp stalk core powder biomass rubber composite material, Wang Jie, Doctoral dissertation of Beijing University of Chemical Technology, 2011.05; and, Study on modification of hemp stalk core powder by maleic anhydride catalyzed by ferrous sulfate, Qu Xiaoling et al., Chemistry and Adhesion, 2020, 42(02).

[0007] Among them, Chinese patent CN202110277187.X: A method for preparing modified hemp stalk core powder composite material, which involves modifying hemp stalk core powder and combining it with composite materials such as polyethylene to improve the performance of the composite material and increase the utilization value of hemp stalk core.

[0008] Chinese Patent CN202010165197.X: A waterborne UV-curable coating modified with hemp stalk core powder, its preparation method, and its application. The method involves first reacting polyethylene glycol acrylate, a catalyst, a polymerization inhibitor, and diisocyanate to obtain an intermediate product; then reacting hemp stalk core powder, the catalyst, the polymerization inhibitor, and the intermediate product to obtain hydrophilic UV-curable modified hemp stalk core powder; finally, adding the hydrophilic UV-curable modified hemp stalk core powder to a waterborne UV-curable coating. This method provides a new approach to coating modification.

[0009] Chinese Patent CN202210575252.1: A method for preparing antibacterial pulp board and carbon-loaded mulch film paper using hemp stalk core, corn cob and rice straw. This method develops a process implementation path that combines biological enzymatic hydrolysis and mechanical force to decompose the three elements of plants (cellulose, hemicellulose and lignin) and simultaneously modify the trisaccharides (C6, C5 and C9). The cellulose molecule structure obtained is loaded with a large number of antibacterial active groups and hemicellulose microcrystals, which endow the target product with unique functionality.

[0010] Chinese Patent CN202211303323.9: A modified hemp stalk core powder, a reinforced polypropylene composite material, and a method for preparing the same. The method involves crushing and ball milling waste hemp stalk cores, followed by chemical treatment with alkali and silane coupling agents to obtain modified hemp stalk core powder. This modified hemp stalk core powder is then mixed with polypropylene, inorganic nanoparticles, plasticizers, and antioxidants at high speed, followed by melt grafting, extrusion, and pelletizing to obtain modified hemp stalk core powder / polypropylene composite material granules. Finally, samples are obtained through injection molding. The prepared modified hemp stalk core powder / polypropylene composite material not only possesses excellent mechanical properties, corrosion resistance, and processing performance, but also exhibits green environmental protection and a strong wood-like texture. It can be used to replace general injection molding PP materials and can be widely applied in toys, outer packaging boxes, personalized art pieces, and other fields.

[0011] The article "Preparation and Structure and Properties of Hemp Stalk Core Powder Biomass Rubber Composites" proposes using pulverized hemp stalk core powder (HP) as a filler in rubber, studying its influence on the structure and properties of the filled rubber, as well as the changes in the structure and properties of the rubber after being blended with commonly used silica, nylon, and aramid short fibers, to explore its feasibility for use in the rubber industry. This study compares traditional modification processes where solid binder modification significantly improves water resistance. Through research on the structure and properties of SBR / NR rubber filled with different modified HP, it is concluded that emulsion-co-precipitation modification is superior to Si69 high-mixing modification. Furthermore, the comprehensive mechanical properties of the rubber composite are best when the HP filling amount is 30 phr.

[0012] A study on the modification of hemp stalk core powder by maleic anhydride catalyzed by ferrous sulfate: Maleic anhydride was used to modify hemp stalk core powder. The modification effect was best achieved using a 1% ferrous sulfate solution and a 30% maleic anhydride solution. The hemp stalk core powder modified with maleic anhydride exhibited a rough surface and entangled particles, with a significant decrease in hydrophilicity.

[0013] The above research focuses primarily on the modification and application of hemp stalk core powder. From the research content, it's clear that the modification process requires the use of chemicals for further processing, which inevitably increases application costs. Furthermore, the ease of technology transfer, the effectiveness of the product, and the secondary pollution caused by production must be considered. Therefore, it is necessary to further explore new applications for hemp stalk core powder and develop simpler and easier-to-implement application methods. Summary of the Invention

[0014] The purpose of this invention is to provide a hemp stalk core powder slurry composition and its application. This slurry composition has a simple composition and can be used to prepare packaging paper. On the one hand, it can expand the application of hemp stalk core, and on the other hand, it can simplify the process of preparing packaging paper from hemp stalk core. It is also relatively environmentally friendly and has low production costs.

[0015] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0016] In a first aspect, the present invention provides a hemp stalk core powder slurry composition, wherein the composition comprises, by weight, 70-90 parts of hemp stalk core powder, 2-10 parts of softener, 2-10 parts of reinforcing agent, 1-10 parts of adhesive, 0-10 parts of calcium carbonate, 0-1.0 parts of defoamer, and 0-0.5 parts of dispersant; wherein the hemp stalk core is 100-200 mesh particles.

[0017] Preferably, the composition comprises, by weight, 85-90 parts hemp stalk core powder, 6-7 parts softener, 2-5 parts reinforcing agent, 1-3 parts adhesive, 0.1-0.2 parts defoamer, and 0.02-0.05 parts dispersant; wherein the hemp stalk core is 150-180 mesh particles.

[0018] Preferably, the softener is selected from propylene glycol and / or glycerol; and / or, the reinforcing agent is selected from at least one of modified starch, guar gum, sodium carboxymethyl cellulose, gum arabic, and sodium alginate; and / or, the adhesive is styrene-butadiene latex; and / or, the defoaming agent is FBX-01; and / or, the dispersant is polyethylene oxide.

[0019] In a second aspect, the present invention provides the use of the composition described in the first aspect in the preparation of packaging paper.

[0020] Preferably, the packaging paper is a special packaging paper.

[0021] Thirdly, the present invention provides a method for preparing packaging paper, comprising the following steps:

[0022] Step 1: Prepare the fiber pulp into base paper;

[0023] Step 2: Prepare hemp stalk core powder slurry by using water to prepare the composition described in the first aspect;

[0024] Step 3: The base paper is combined with the hemp stalk core powder slurry, and then dried a second time.

[0025] Preferably, in step 1, the fiber pulp is obtained by beating at least one of softwood pulp, hardwood pulp, hemp fiber pulp, and bamboo pulp; more preferably, the beating control parameters include: beating concentration: 1.0-4.5%, power 100-140KW, time 20-45min, and beating degree: 15-40°SR; even more preferably, the beating control parameters include: beating concentration: 3.0-4.0%, power 120-130KW, time 35-45min, and beating degree: 25-35°SR.

[0026] Preferably, in step 1, the process of preparing the base paper from the fiber pulp includes: mixing the fiber pulp with dispersant II, defoamer, and wet strength agent, and sequentially performing wire forming, press dewatering, and primary drying to obtain the base paper; more preferably, a cylinder paper machine is used for wire forming, and the speed of the cylinder paper machine is preferably 100-200 m / min, more preferably 100-150 m / min; the control parameters for wire forming include: wire density: 0.02%-0.20%; paper exit moisture content: 80%-90%; paper moisture content after press dewatering: 50%-65%; primary drying temperature: 85-125℃;

[0027] More preferably, the second dispersant is an anionic polyacrylamide solution or polyethylene oxide solution with a mass concentration of 0.02%-0.03%, and the amount of the second dispersant added is 0.2-0.8% of the oven-dry mass of the fiber pulp; and / or,

[0028] The defoamer is white mineral oil or Dow Corning MEM-8031, and the amount of defoamer added is 0.05%-0.2% of the oven-dry weight of the fiber pulp; and / or,

[0029] The wet strength agent is a polyamide epichlorohydrin resin solution with a mass concentration of 1.0-5.0%, and the amount of wet strength agent added is 0.2%-1.0% of the oven-dry mass of the fiber pulp.

[0030] Preferably, in step 3, the base paper is compounded with hemp stalk core powder slurry using a steel plate machine with a speed preferably of 100-200 m / min, more preferably 100-150 m / min; and / or, the secondary drying temperature is 70-125°C, and the moisture content of the dried packaging paper is controlled to be 7%-11%.

[0031] Preferably, the solid content of the hemp stalk core powder slurry is 15% to 30%, and the viscosity is 1500 to 7000 cp.

[0032] The technical advantages of this invention are as follows:

[0033] This invention provides a hemp stalk core powder slurry composition. The slurry formed from this composition can be directly used as the main material for coatings and laminated with base paper to produce packaging paper, especially specialty packaging paper. This eliminates the need for modification of the hemp stalk core powder, enabling the obtained specialty packaging paper to possess excellent performance and environmental friendliness. Furthermore, the production process of specialty packaging paper is simple and easy to operate, with no powder loss, minimal pollution, reduced difficulty in treating papermaking wastewater, high efficiency, low cost, and advantages for market promotion. Attached Figure Description

[0034] Figure 1 This is a physical image of the special packaging paper obtained in Application Example 4 of the present invention. Detailed Implementation

[0035] In the description of this invention, it should be noted that unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] The technical requirements for packaging paper products are shown in Tables 1 and 2:

[0037] Table 1 Technical Specifications for Base Paper:

[0038] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 15-60 2 Longitudinal tensile strength kN / m ≥0.45 3 transverse tensile strength kN / m ≥0.15 4 Longitudinal wet tensile strength kN / m ≥0.10 5 Longitudinal elongation ％ ≥1.2 6 Breathability CU ≥3000 7 Moisture ％ 4-7

[0039] Table 2 Technical Specifications of Special Packaging Paper in Embodiments of the Invention (2)

[0040]

[0041]

[0042] In an application example of the present invention, the method for preparing special packaging paper includes the following steps:

[0043] Step 1: Prepare the fiber pulp into base paper;

[0044] Step 2: Prepare the hemp stalk core powder slurry composition using water. The hemp stalk core powder in the slurry composition is obtained by crushing hemp stalk cores. The moisture content of the hemp stalk cores is best controlled between 5% and 8%. If the moisture content is too high, the raw material will become sticky and difficult to crush, affecting the grinding of particles and wasting energy. If the moisture content is too low, a paste-like consistency will occur during fine grinding.

[0045] Step 3: Finally, the base paper is laminated with hemp stalk core powder slurry, and then dried a second time.

[0046] The preparation process of the base paper includes: mixing fiber pulp with dispersant, defoamer, and wet strength agent; using a cylinder paper machine, sequentially performing wire forming, press dewatering, and primary drying to obtain the base paper. The preferred cylinder paper machine speed is 100–200 m / min, more preferably 100–150 m / min. The control parameters for wire forming include: wire density: 0.02%–0.20%; paper exit moisture content: 80%–90%; paper moisture content after press dewatering: 50%–65%; primary drying temperature: 85–125℃. The dispersant is a 0.02%–0.03% (w / w) anionic polyacrylamide (APAM) solution or polyethylene oxide (PEO) solution, added at 0.2%–0.8% of the oven-dry weight of the fiber pulp. The defoamer is white mineral oil or Dow Corning MEM-8031, added at 0.05%–0.2% of the oven-dry weight of the fiber pulp. The wet strength agent is a polyamide epichlorohydrin resin (PAE) solution with a mass concentration of 1.0-5.0%, and the amount added is 0.2%-1.0% of the oven-dry mass of the fiber pulp.

[0047] The fiber pulp is obtained by beating at least one of softwood pulp, hardwood pulp, hemp fiber pulp, and bamboo pulp. The beating control parameters include: beating concentration: 1.0-4.5%, power 100-140KW, time 20-45min, and freeness: 15-40°SR. Preferably, the beating control parameters include: beating concentration: 3.0-4.0%, power 120-130KW, time 35-45min, and freeness: 25-35°SR.

[0048] The base paper is laminated with hemp stalk core powder slurry on a steel plate laminating machine at a speed of 100-200 m / min.

[0049] The secondary drying temperature is 70–125℃, and the moisture content of the dried packaging paper is controlled to be 7%–11%.

[0050] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, the following embodiments are limited to a part of the research of the present invention and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on this, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present invention. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0051] Example 1

[0052] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight: 90 parts hemp stalk core powder, 5 parts propylene glycol, 1 part guar gum, 2 parts sodium carboxymethyl cellulose, 2 parts styrene-butadiene latex, 0.15 parts FBX-01, and 0.06 parts polyethylene oxide (PEO); the hemp stalk core is 150 mesh particles with a moisture content of 6.5%.

[0053] Example 2

[0054] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight: 80 parts hemp stalk core powder, 7 parts propylene glycol, 5 parts guar gum, 3 parts styrene-butadiene latex, 5 parts calcium carbonate, 0.1 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 150 mesh particles with a moisture content of 6.5%.

[0055] Example 3

[0056] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 85 parts hemp stalk core powder, 7 parts propylene glycol, 5 parts guar gum, 3 parts styrene-butadiene latex, 0.1 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 150 mesh particles with a moisture content of 6.5%.

[0057] Example 4

[0058] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 85 parts hemp stalk core powder, 7 parts propylene glycol, 3 parts guar gum, 2 parts sodium carboxymethyl cellulose, 3 parts styrene-butadiene latex, 0.15 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 150 mesh particles with a moisture content of 6.5%.

[0059] Example 5

[0060] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight: 87 parts hemp stalk core powder, 7 parts propylene glycol, 3 parts guar gum, 2 parts sodium carboxymethyl cellulose, 1 part styrene-butadiene latex, 0.15 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 150 mesh particles with a moisture content of 6.5%.

[0061] Example 6

[0062] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 85 parts hemp stalk core powder, 7 parts propylene glycol, 3 parts guar gum, 2 parts sodium carboxymethyl cellulose, 3 parts styrene-butadiene latex, 0.15 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 180 mesh particles with a moisture content of 6.5%.

[0063] Example 7

[0064] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 85 parts hemp stalk core powder, 7 parts propylene glycol, 3 parts guar gum, 2 parts sodium carboxymethyl cellulose, 3 parts styrene-butadiene latex, 0.15 parts FBX-01, and 0.05 parts PEO; the hemp stalk core is 200 mesh particles with a moisture content of 6.5%.

[0065] Example 8

[0066] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 88 parts hemp stalk core powder, 6 parts propylene glycol, 1 part guar gum, 2 parts sodium carboxymethyl cellulose, 2 parts styrene-butadiene latex, 0.07 parts FBX-01, and 0.03 parts PEO; the hemp stalk core is 180 mesh particles with a moisture content of 6.5%.

[0067] Example 9

[0068] This embodiment provides a hemp stalk core powder slurry composition, which comprises, by weight, 89.5 parts hemp stalk core powder, 6 parts propylene glycol, 0.5 parts guar gum, 2 parts sodium carboxymethyl cellulose, 2 parts styrene-butadiene latex, 0.15 parts FBX-01, and 0.06 parts PEO; the hemp stalk core is 100 mesh particles with a moisture content of 6.5%.

[0069] Comparative Example 1

[0070] This embodiment provides a hemp stalk core powder slurry composition, which differs from Example 1 in that the hemp stalk core is made of 80-mesh particles.

[0071] Comparative Example 2

[0072] This embodiment provides a hemp stalk core powder slurry composition, which differs from Example 1 in that the hemp stalk core is made of 220 mesh particles.

[0073] Application Example 1

[0074] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 1, and specifically includes the following steps:

[0075] 1. Production of base paper

[0076] 1) Fiber raw material: bleached softwood pulp; 2) Cylinder paper machine and steel plate machine: speed 100m / min.

[0077] 3) Pulping process: 100% bleached softwood pulp, pulping concentration 3.5%, power 120KW, time 45min, pulping degree 30°SR.

[0078] 4) Addition of chemical additives: Dispersant polyacrylamide APAM solution added at 0.3% (mass concentration 0.03%); defoamer Dow Corning MEM-8031 added at 0.08%; wet strength agent PAE solution added at 0.5% (mass concentration 3.0%). All additions are based on oven-dry pulp weight.

[0079] (5) On-wire density: 0.05%; On-wire moisture content: 90%; On-press moisture content: 63%; Drying cylinder temperature: 100℃. The technical specifications of the obtained base paper are shown in Table 3.

[0080] Table 3 Technical Specifications of Base Paper

[0081]

[0082]

[0083] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 1 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.3% and the viscosity was 2380cp.

[0084] 3. The base paper is laminated with hemp stalk core powder slurry using a cylinder paper machine at a speed of 100 m / min. After lamination, a second drying process is performed at a temperature of 85-100℃, controlling the moisture content of the dried packaging paper to 9.3%. The technical specifications of the obtained special packaging paper are shown in Table 4.

[0085] Table 4. Test Indicators for Special Packaging Paper

[0086]

[0087] Application Example 2:

[0088] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 2, and specifically includes the following steps:

[0089] 1. Production of base paper: Same as in application example 1.

[0090] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 2 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.7% and the viscosity was 4521cp.

[0091] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0092] Table 5. Test Indicators for Special Packaging Paper

[0093]

[0094]

[0095] Application Example 3

[0096] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 3, and specifically includes the following steps:

[0097] 1. Production of base paper: Same as in application example 1.

[0098] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 3 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 16.2% and the viscosity was 4781cp.

[0099] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0100] Table 6. Test Indicators for Special Packaging Paper

[0101]

[0102] Application Example 4

[0103] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 4, and specifically includes the following steps:

[0104] 1. Production of base paper: Same as in application example 1.

[0105] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 4 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.6% and the viscosity was 3950cp.

[0106] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0107] Table 7. Test Indicators for Special Packaging Paper

[0108]

[0109] Application Example 5

[0110] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 5, and specifically includes the following steps:

[0111] 1. Production of base paper: Same as in application example 1.

[0112] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 5 was used, and water was added to prepare hemp stalk core powder slurry, wherein the slurry solid content was 16.5% and the viscosity was 4848cp;

[0113] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0114] Table 8. Test Indicators for Special Packaging Paper

[0115]

[0116]

[0117] Application Example 6

[0118] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 6, and specifically includes the following steps:

[0119] 1. Production of base paper: Same as in application example 1.

[0120] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 6 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.1% and the viscosity was 5023cp.

[0121] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0122] Table 9. Test Indicators for Special Packaging Paper

[0123]

[0124] Application Example 7

[0125] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 7, and specifically includes the following steps:

[0126] 1. Production of base paper: Same as in application example 1.

[0127] 2. Preparation of hemp stalk powder and hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 7 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.8% and the viscosity was 6023cp.

[0128] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0129] Table 10 Test Indicators for Special Packaging Paper

[0130]

[0131] Application Example 8

[0132] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 8, and specifically includes the following steps:

[0133] 1. Production of base paper: Same as in Example 1.

[0134] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 8 was used and water was added to prepare hemp stalk core powder slurry, wherein the slurry solid content was 16.9% and the viscosity was 3080cp.

[0135] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0136] Table 11 Test Indicators for Special Packaging Paper

[0137]

[0138] Application Example 9

[0139] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 9, and specifically includes the following steps:

[0140] 1. Production of base paper: Same as in Example 1.

[0141] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 9 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.9% and the viscosity was 3050cp.

[0142] 3. Example 1: Composite application of base paper and hemp stalk core powder slurry.

[0143] Table 12 Test Indicators for Special Packaging Paper

[0144]

[0145] Application Example 10

[0146] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 4, and specifically includes the following steps:

[0147] 1. Production of base paper:

[0148] 1) Fiber raw material: bleached hemp fiber pulp; 2) Cylinder paper machine and steel plate machine: speed 100m / min.

[0149] 3) Pulping process: 100% bleached hemp fiber pulp: pulping concentration 2.0%, power 120KW, pulping degree 25°SR.

[0150] 4) Chemical additives: Dispersant polyacrylamide (APAM) added at 0.5% (mass concentration 0.03%); defoamer white mineral oil added at 0.08%; wet strength agent PAE solution added at 0.5% (mass concentration 1.5%). All additions are based on oven-dry slurry weight.

[0151] 5) On-line density: 0.04%; moisture content at the wire exit: 80%–90%; moisture content at the press exit: 55%–65%; temperature of the main drying cylinder: 100℃. The technical specifications of the obtained base paper are shown in Table 13.

[0152] Table 13 Technical Specifications of Base Paper

[0153] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 19.5 2 Longitudinal tensile strength kN / m 0.83 3 transverse tensile strength kN / m 0.35 4 Longitudinal wet tensile strength kN / m 0.12 5 Longitudinal elongation ％ 1.81 6 Breathability CU 8150 7 Moisture ％ 4.1

[0154] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 4 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.8% and the viscosity was 4050cp.

[0155] 3. Application Example 1: Composite of base paper and hemp stalk core powder pulp. The technical specifications of the obtained specialty packaging paper are shown in Table 14.

[0156] Table 14 Test Indicators for Special Packaging Paper

[0157]

[0158] Application Example 11

[0159] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 4, and specifically includes the following steps:

[0160] 2. Production of base paper:

[0161] 1) Fiber raw materials: 80% bleached hemp fiber pulp and 20% bamboo pulp; 2) Cylinder paper machine and steel plate machine: speed 100m / min.

[0162] 3) Pulping process: 100% bleached hemp fiber pulp: pulping concentration 2.0%, power 120KW, pulping degree 25°SR.

[0163] 4) Addition of chemical additives: Dispersant polyacrylamide (APAM) solution added at 0.4% (mass concentration 0.03%); defoamer Dow Corning MEM-8031 added at 0.06%; wet strength agent PAE solution with mass concentration 1.5% added at 0.5%. All additions are based on oven-dry pulp weight.

[0164] 5) On-line density: 0.04%; moisture content at the wire exit: 80%–90%; moisture content at the press exit: 55%–65%; temperature of the main drying cylinder: 100℃. The technical specifications of the obtained base paper are shown in Table 13.

[0165] Table 15 Technical Specifications of Base Paper

[0166] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 20.1 2 Longitudinal tensile strength kN / m 0.65 3 transverse tensile strength kN / m 0.28 4 Longitudinal wet tensile strength kN / m 0.12 5 Longitudinal elongation ％ 1.81 6 Breathability CU 5530 7 Moisture ％ 4.1

[0167] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 4 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.5% and the viscosity was 3850 cp.

[0168] 3. Application Example 1: Composite of base paper and hemp stalk core powder pulp. The technical specifications of the obtained specialty packaging paper are shown in Table 14.

[0169] Table 16 Test Indicators for Special Packaging Paper

[0170]

[0171] Application Example 12

[0172] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Example 4, and specifically includes the following steps:

[0173] 1. Production of base paper

[0174] 1) Fiber raw material: bleached softwood pulp; 2) Cylinder paper machine and steel plate machine: speed 100m / min.

[0175] 3) Pulping process: 100% bleached softwood pulp, pulping concentration 3.5%, power 120KW, time 30min, pulping degree 25°SR.

[0176] 4) Chemical additives: dispersant polyacrylamide (APAM) solution 0.2%, mass concentration 0.02%; defoamer Dow Corning MEM-8031 added 0.05%; wet strength agent PAE solution mass concentration 1.5%, added 0.3%. All additions are based on oven-dry slurry weight.

[0177] 5) On-wire density: 0.1%; On-wire moisture content: 80%–90%; On-press moisture content: 59%; Drying cylinder temperature: 110℃. The technical specifications of the obtained base paper are shown in Table 15.

[0178] Table 17 Technical Specifications of Base Paper

[0179] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 30.3 2 Longitudinal tensile strength kN / m 1.05 3 transverse tensile strength kN / m 0.35 4 Longitudinal wet tensile strength kN / m 0.13 5 Longitudinal elongation ％ 1.75 6 Breathability CU 3100 7 Moisture ％ 5.6

[0180] 2. Preparation of hemp stalk core powder slurry: The hemp stalk core powder slurry composition of Example 4 was used and water was added to prepare hemp stalk core powder slurry, wherein the solid content of the slurry was 15.6% and the viscosity was 4010cp.

[0181] 3. Application Example 1: Composite of base paper and hemp stalk core powder pulp. The technical specifications of the obtained specialty packaging paper are shown in Table 16.

[0182] Table 18 Test Indicators for Special Packaging Paper

[0183]

[0184]

[0185] Comparative Application Example 1

[0186] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Comparative Example 1. The specific steps are the same as in Application Example 1, and the technical indicators of the obtained base paper are shown in Table 19.

[0187] Table 19 Technical Specifications of Base Paper

[0188] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 17.9 2 Longitudinal tensile strength kN / m 0.80 3 transverse tensile strength kN / m 0.17 4 Longitudinal wet tensile strength kN / m 0.16 5 Longitudinal elongation ％ 1.80 6 Breathability CU 6310 7 Moisture ％ 6.2

[0189] The solid content of the hemp stalk core powder is 15.8%, and the viscosity is 2210 cp. The particle size of the hemp stalk core powder is 80 mesh.

[0190] The technical specifications of the obtained special packaging paper are shown in Table 20.

[0191] Table 20 Test Indicators for Special Packaging Paper

[0192]

[0193]

[0194] Comparative Application Example 2

[0195] This application example provides a method for preparing special packaging paper, which uses the hemp stalk core powder slurry composition of Comparative Example 2. The specific steps are the same as in Application Example 1, and the technical indicators of the obtained base paper are shown in Table 21.

[0196] Table 21 Technical Specifications of Base Paper

[0197] Serial Number project unit Indicator Testing 1 Quantitative <![CDATA[g / m 2 ]]> 18.5 2 Longitudinal tensile strength kN / m 1.13 3 transverse tensile strength kN / m 0.19 4 Longitudinal wet tensile strength kN / m 0.20 5 Longitudinal elongation ％ 1.80 6 Breathability CU 5920 7 Moisture ％ 6.0

[0198] The solid content of the slurry in hemp stalk core powder is 14.8%, and the viscosity is 4591 cp.

[0199] The technical specifications of the obtained special packaging paper are shown in Table 22.

[0200] Table 22 Test Indicators for Special Packaging Paper

[0201]

[0202]

[0203] In summary, the present invention utilizes hemp stalk core powder in the preparation of special packaging paper, and has the following advantages:

[0204] 1. No loss of hemp stalk core powder: After the hemp stalk core powder is used to prepare the pulp, it is laminated with the base paper without going through the wet papermaking process. It does not require a squeegee or vacuum dewatering. The prepared pulp does not flow into the white water system during dewatering, but is completely attached to the base paper and enters the oven drying system to evaporate the moisture to the required dryness.

[0205] 2. Low wastewater pollution and light treatment load: Because the prepared hemp stalk core powder slurry does not flow into the white water system during dewatering, it does not enter the wastewater discharge system, thus avoiding an increase in wastewater treatment load (because plant powder and wood pulp fiber are not easily fermented and deteriorated, COD levels would increase significantly and are difficult to treat, making it hard to meet discharge standards, and SS would also increase significantly, unlike fillers in papermaking, where plant powder and wood pulp fiber contain a large amount of floating matter, increasing filtration difficulty compared to traditional sedimentation methods). This invention, by combining base paper with hemp stalk core powder slurry, does not increase wastewater load and requires no separate treatment. It is environmentally friendly and reduces wastewater treatment costs.

[0206] The wastewater discharge and treatment results of the preparation process in Examples 1-12 of this invention are as follows:

[0207] COD influent: 2000-2500, effluent COD: 60-70; BOD influent: 400-500, effluent BOD: less than 20; SS influent: 1500-3000 mg / L, effluent SS: 15-35 mg / L.

[0208] 3. Low production cost

[0209] (1) Low raw material cost: wood pulp fiber costs 4,500-6,500 yuan / ton, while hemp stalk core costs 300-500 yuan / ton. Calculated at a ratio of 1:1.5, the cost of fiber raw materials can be reduced by 44.8%.

[0210] (2) Reduced water consumption: Hemp stalk core pulp has a high solid content, and the water used in the process of using wood pulp fiber can be reused, which can reduce water consumption by 15% for the same amount.

[0211] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing packaging paper, characterized in that, Includes the following steps: Step 1: Prepare the fiber pulp into base paper; Step 2: Prepare the hemp stalk core powder slurry composition using water; Step 3: The base paper is combined with the hemp stalk core powder slurry, and then dried a second time. The hemp stalk core powder slurry composition comprises, by weight, 70-90 parts hemp stalk core powder, 2-10 parts softener, 2-10 parts reinforcing agent, 1-10 parts adhesive, 0-10 parts calcium carbonate, 0.07-1.0 parts defoamer, and 0.03-0.5 parts dispersant one; the hemp stalk core is 100-200 mesh particles; the softener is selected from propylene glycol and / or glycerol; the reinforcing agent is selected from at least one of modified starch, guar gum, sodium carboxymethyl cellulose, gum arabic, and sodium alginate; the adhesive is styrene-butadiene latex; the defoamer is FBX-01; and the dispersant one is polyethylene oxide. In step 3, the base paper is compounded with hemp stalk core powder slurry using a steel plate machine with a speed of 100~200m / min and a secondary drying temperature of 70~125℃. The moisture content of the dried packaging paper is controlled to be 7%~11%.

2. The preparation method according to claim 1, characterized in that, The composition of the hemp stalk core powder slurry by weight is as follows: 85-90 parts hemp stalk core powder, 6-7 parts softener, 2-5 parts reinforcing agent, 1-3 parts adhesive, 0.1-0.2 parts defoamer, and 0.02-0.05 parts dispersant; the hemp stalk core is 150-180 mesh particles.

3. The preparation method according to claim 1, characterized in that, The packaging paper is a special type of packaging paper.

4. The preparation method according to claim 1, characterized in that, In step 1, the fiber pulp is obtained by pulping at least one of softwood pulp, hardwood pulp, hemp fiber pulp, and bamboo pulp.

5. The preparation method according to claim 4, characterized in that, The control parameters for pulping include: pulping concentration 1.0-4.5%, power 100-140kW, time 20-45min, and freeness 15-40°SR.

6. The preparation method according to claim 5, characterized in that, The control parameters for pulping include: pulping concentration 3.0-4.0%, power 120-130kW, time 35-45min, and freeness 25-35°SR.

7. The preparation method according to any one of claims 1 to 6, characterized in that, In step 1, the process of preparing the fiber pulp into base paper includes: mixing the fiber pulp with dispersant II, defoamer and wet strength agent, and then sequentially performing wire forming, pressing and dehydration, and one-time drying to obtain the base paper.

8. The preparation method according to claim 7, characterized in that, The paper is formed on a rotary paper machine. The control parameters for the paper forming process include: wire density: 0.02%-0.20%; paper moisture content at the wire exit: 80%~90%; paper moisture content after pressing and dewatering: 50%~65%; and primary drying temperature: 85~125℃.

9. The preparation method according to claim 8, characterized in that, The speed of the rotary paper machine is 100~200m / min.

10. The preparation method according to claim 9, characterized in that, The speed of the rotary paper machine is 100~150 m / min.

11. The preparation method according to claim 7, characterized in that, The second dispersant is an anionic polyacrylamide solution or polyethylene oxide solution with a mass concentration of 0.02%-0.03%, and the amount of the second dispersant added is 0.2-0.8% of the oven-dry mass of the fiber pulp; and / or, The defoamer is white mineral oil or Dow Corning MEM-8031, and the amount of defoamer added is 0.05%-0.2% of the oven-dry weight of the fiber pulp; and / or, The wet strength agent is a polyamide epichlorohydrin resin solution with a mass concentration of 1.0-5.0%, and the amount of wet strength agent added is 0.2%-1.0% of the oven-dry mass of the fiber pulp.

12. The preparation method according to claim 1, characterized in that, In step 3, the speed of the steel plate machine is 100~150 m / min.

13. The preparation method according to claim 1, characterized in that, The solid content of the hemp stalk core powder slurry is 15%~30%, and the viscosity is 1500~7000cp.

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