Preparation method of environment-friendly straw paper with hydrophobic and lip-sticking-free performance

Abstract

The invention provides a preparation method of environment-friendly straw paper with hydrophobic and lip-sticking-free properties. The preparation method comprises the following steps: respectively pulping bleached softwood pulp and bleached hardwood pulp, and mixing to obtain a fiber mixture; adding a biological wax waterproof system sizing agent into the fiber mixture, or adding the biological wax waterproof system sizing agent and an antibacterial agent, and adding a wet strength agent and an alkyl ketene dimer, and carrying out net forming treatment; the preparation method comprises the following steps: carrying out squeezing dehydration and primary drying treatment on paper pulp subjected to net forming treatment, carrying out surface coating and sizing by adopting a sizing system containing a biological wax waterproof system sizing agent, carrying out secondary drying treatment, and finally sequentially carrying out calendering and coiling to obtain the environment-friendly straw paper. Experiments show that the straw paper disclosed by the invention has the advantages of excellent hydrophobicity, no lip sticking, high strength, high antibacterial property, complete degradability, no toxicity and environment friendliness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of papermaking, in particular to a preparation method of environment-friendly straw paper with hydrophobic and non-lipstick sticking performance. BACKGROUND

[0002] With the introduction of a series of plastic straw bans in China, the beverage industry actively responds to national policies and no longer uses non-degradable disposable plastic straws. Paper straws have become an important environmental product to replace plastic straws due to their environmental degradability. Looking at the global straw production, in 2021, the global disposable straw production reached 2856.3 billion, and the disposable paper straw production reached 738.9 billion, accounting for 25.87%. In 2022, the global paper straw market value was about 1.38 billion US dollars, and it is expected to grow at a healthy rate of more than 8.1% during the forecast period 2023-2029. It can be seen that with the increase of market share, environment-friendly paper straws are the future trend of straws, and therefore, the demand for paper straw processing straw paper will also gradually increase with the development of paper straws.

[0003] Although paper straw products are the trend of the times, the use performance of paper straws is also a barrier to their development. Due to many problems in the processing technology that are difficult to overcome, the existing straw paper often has multiple problems such as sticking to the lips, soft tube, and unsmooth sucking, which leads to poor experience. Consumers also joke that paper straws are "milk tea killers" and "sugar abstinence helpers". Therefore, how to improve the use performance of paper straws is a problem that needs to be solved at present.

[0004] For example, in the selection of sizing agents, sodium carboxymethyl cellulose and alkyl alkene ketone dimer are two commonly used sizing agents for preparing straw paper. Among them, sodium carboxymethyl cellulose (CMC) can improve the surface strength of paper, but the surface of the straw paper prepared by using the sizing agent is not tight enough, and the waterproof and moisture-proof performance is poor, which cannot meet the demand of hydrophobic and non-lipstick sticking of straw paper. Alkyl alkene ketone dimer is a neutral sizing agent, and during the drying process, the esterification reaction between the lactone ring on the dimer molecule and the hydroxyl group on the fiber molecule spreads, producing sizing effect. However, the sizing needs a curing process, and a long time is needed to achieve the best water resistance. Moreover, excessive and insufficient sizing have adverse effects, among which, excessive sizing will cause AKD wax powder to fall off during slitting and tube rolling, and insufficient sizing cannot achieve water resistance, which limits its further application.

[0005] Currently, there are also methods of producing non-lipstick sticking straw paper by off-machine printing water-based gloss oil, but the hydrophobic performance cannot meet the requirements, and many water-based gloss oils have the problem of exceeding mineral oil. There are also methods of producing hydrophobic and non-lipstick sticking straw paper by off-machine coating PLA, but the strength, temperature resistance and degradation storage time of PLA cannot meet the general requirements. SUMMARY

[0006] In order to better solve the problems of poor hydrophobicity, sticking lips, insufficient strength, existence of harmful substances and poor antibacterial property of the existing straw paper, the application provides a preparation method of environment-friendly straw paper with hydrophobic and non-lip-sticking performance.

[0007] To solve the above technical problems, the technical scheme adopted by the application is:

[0008] In the first aspect, the application provides a preparation method of environment-friendly straw paper with hydrophobic and non-lip-sticking performance, which comprises the following steps:

[0009] Step 1, the bleached coniferous wood pulp and the bleached broadleaf wood pulp are respectively subjected to beating treatment, and then mixed according to the weight percentage composition of coniferous wood pulp fiber (25-45) % and broadleaf wood pulp fiber (55-75) % to obtain a fiber mixture;

[0010] Step 2, the fiber mixture is fed into a headbox through a pressure screen, a biological wax waterproof system sizing agent is added at the inlet of the pressure screen, or a biological wax waterproof system sizing agent and an antibacterial agent are added at the inlet of the pressure screen, and a wet strength agent and an alkyl alkene ketone dimer are added at the outlet of the pressure screen, and an on-machine forming treatment is performed;

[0011] Step 3, the paper pulp after the on-machine forming treatment is subjected to a pressing dewatering and a first drying treatment to obtain a semi-dry paper sheet with a water content of (5.5-6.5) %;

[0012] Step 4, the semi-dry paper sheet is subjected to surface coating sizing with a sizing system containing a biological wax waterproof system sizing agent;

[0013] Step 5, the paper sheet after the surface coating sizing is subjected to a second drying treatment;

[0014] Step 6, the paper sheet after the second drying treatment is sequentially subjected to calendering and winding to obtain the environment-friendly straw paper.

[0015] Preferably, in the step 1, the control parameters of the beating treatment of the two wood pulp raw materials are: the beating consistency is (3.8-4.0) %, the beating degree / wet weight of the bleached coniferous wood pulp is (35-40) °SR / (3.5-4.5) g, and the beating degree / wet weight of the bleached broadleaf wood pulp is (30-35) °SR / (1.0-3.0) g.

[0016] Preferably, in the step 2, the additives are composed of the biological wax waterproof system sizing agent (0.12-0.2) %, the antibacterial agent (0.3-0.5) %, the wet strength agent (0.9-1.2) %, and the alkyl alkene ketone dimer (1.0-1.2) % according to the mass percentage composition in the mixed system; further preferably, the antibacterial agent is a biological polysaccharide antibacterial agent; and the wet strength agent is an environment-friendly chlorine-free propyl alcohol wet strength agent.

[0017] Preferably, in the step 3, the control condition of the press dewatering is that the three-stage press dewatering is adopted, and the press pressures are set as 80 KN / m, 80 KN / m and 100 KN / m in sequence; and / or the control process of the once drying treatment is that the paper sheet after the press dewatering is sequentially passed through 24-26 drying cylinders, wherein the temperatures of the first 7-9 drying cylinders are controlled at (65-90) ℃, and the temperatures of the last 16-18 drying cylinders are controlled at (110-120) ℃.

[0018] Preferably, in the step 4, the half-dry paper sheet is coated and sized on one surface by using a sizing system containing a biological wax waterproof system sizing agent, and the other surface is coated with water.

[0019] Further preferably, the sizing system containing the biological wax waterproof system sizing agent is used in an amount of (10-15) kg / t of the environment-friendly straw paper, and the water is used in an amount of (5-8) kg / t of the environment-friendly straw paper.

[0020] More preferably, the sizing system containing the biological wax waterproof system sizing agent is a solution prepared by compounding the biological wax waterproof system sizing agent and sodium carboxymethyl cellulose; further more preferably, in the sizing system, the mass percentage content of the biological wax waterproof system sizing agent is (11-13) %, the mass percentage content of the sodium carboxymethyl cellulose is (2-4) wt %, and the solvent is water.

[0021] Preferably, in the step 5, the control process of the secondary drying treatment is that the paper sheet after the surface coating and sizing is sequentially passed through 11-13 drying cylinders for drying, wherein the temperatures of the first 9-11 drying cylinders are controlled at (80-120) ℃, and the temperatures of the last 1-3 drying cylinders are controlled at (45-65) ℃.

[0022] In the second aspect, the present application provides an environment-friendly straw paper with hydrophobic and non-lipstick-sticking properties, which is obtained by using the preparation method in the first aspect.

[0023] Preferably, the environment-friendly straw paper has a water content of (4.0-5.0) %, a longitudinal wet tensile strength of 0.6-1.0 kN / m, a hydrophobic side dynamic contact angle (0.1S) of 95-140°, and a hydrophobic side Cobb value (60S) of 7.0-22.0 g / m 2 .

[0024] Compared with the prior art, the technical effect of the present application is that:

[0025] Firstly, the preparation method of the environment-friendly straw paper with hydrophobic and non-lipstick-sticking properties can ensure that the straw paper has good hydrophobic and non-lipstick-sticking properties and strength indexes, and can further make the straw paper have antibacterial function. Moreover, the straw paper can be re-pulped, can be composted and degraded, and meets the relevant hygiene and safety standards for food contact paper, and has environmental protection and renewability.

[0026] Second, the preparation method of the environmentally friendly straw paper with hydrophobic and non-lipstick performance of the present application does not need to add fillers such as calcium carbonate and talc in the fiber mixture, maintains high strength of the paper, has good sizing effect, reduces equipment wear and tear, reduces wastewater, and has obvious environmental protection advantages.

[0027] Third, the preparation method of the environmentally friendly straw paper with hydrophobic and non-lipstick performance of the present application has simple process and controllable conditions, greatly improves the use performance of the paper straw, has good application prospect in the preparation of food contact materials, and brings high-quality use experience to the user.

[0028] Fourth, according to the hydrophobic performance and the actual measurement of the liquid wall hanging and dyeing phenomenon on the straw paper after drinking coffee and cola, the environmentally friendly straw paper with hydrophobic and non-lipstick performance of the present application has obviously better hydrophobic performance than the straw paper of Comparative Example 1. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The hydrophobic physical comparison chart of the hydrophobic and non-lipstick environmentally friendly straw paper (A) obtained from Example 1 of the present application and the straw paper (B) of Comparative Example 1.

[0030] Figure 2 The hydrophobic state comparison chart of the straw paper of Example 1 of the present application after single-side water dripping and the straw paper of Comparative Example 1 (the upper one is a conventional straw, and the lower one is a hydrophobic straw).

[0031] Figure 3 The comparison chart of the straw after pipe rolling of the straw paper of Example 1 of the present application and the straw paper of Comparative Example 1 after drinking coffee (the upper one is a conventional straw, and the lower one is a hydrophobic straw).

[0032] Figure 4 The comparison chart of the straw after pipe rolling of the straw paper of Example 1 of the present application and the straw paper of Comparative Example 1 after drinking cola. DETAILED DESCRIPTION

[0033] The present application provides a preparation method of environmentally friendly straw paper with hydrophobic and non-lipstick performance, which optimizes the adding procedures of biological wax waterproof system sizing agent, environmentally friendly wet strength agent, alkyl alkene ketone dimer, and biological polysaccharide antibacterial agent in the pulp, and uses biological wax waterproof system sizing agent and CMC composite formula for single-side hydrophobic surface coating sizing, and the other side is coated with water to prevent warping, which can ensure that the other side of the paper is hydrophobic and non-lipstick without affecting the adhesive pipe rolling on one side of the paper. Compared with the existing preparation technology of straw paper, the present application can not only improve the comprehensive performance of the straw paper such as tensile strength, water resistance, and non-lipstick, but also has antibacterial performance.

[0034] In addition, the present application also optimizes the parameters of the pressing dewatering and multiple drying in the process of preparing the straw paper, such as: the optimization of the pressure configuration in the process of the pressing dewatering and the matching of the paper strength change, the stable dewatering of the first two stages of pressing to consolidate the paper structure, and the appropriate increase of the pressing pressure in the third stage to improve the dryness, which can prevent the wet paper from being crushed and broken by 100%, and can also improve the energy utilization efficiency. The existing pressing process of the straw paper mostly uses 70-120kN / m gradient pressure pressing, and the dewatering process will have 0-10% of the broken paper rate, and the energy consumption is large. The present application also optimizes the drying cylinder configuration and temperature regulation of the twice dewatering, the first drying uses 24-26 drying cylinders, the second drying uses 9-11 drying cylinders, and the low temperature drying mode in the front stage of the first drying and the low temperature drying mode in the rear stage of the second drying can effectively control the paper curling, warping, improve the flatness; the high temperature in the front stage of the second drying can ensure that the glue is fully gelatinized and solidified into a film; the slight rewetting in the rear stage of the low temperature can improve the flexibility and adhesion of the glue film. Compared with the original straw paper making process which uses the same temperature for twice drying, the optimization of the present application can maximize the drying efficiency, reduce the drying defects of the paper, optimize the sizing effect, improve the uniformity and physical strength of the paper, and also optimize the energy utilization rate to a certain extent. At the same time, no harmful substances are introduced in the preparation process, and the raw materials and additives used can be repulped and biodegradable, the preparation method is green and environmentally friendly, which greatly improves the smoking experience and related safety and environmental protection of the paper straw.

[0035] The biological wax waterproof system sizing agent used in the embodiment of the present application is purchased from Shandong Fenghe Shengxin Material Co., Ltd., which only has this kind of biological wax waterproof system sizing agent.

[0036] The biological polysaccharide antibacterial agent used in the embodiment of the present application is purchased from Jinan Shengquan Group Co., Ltd.

[0037] The wet strength agent used in the present application is an environmentally friendly chlorine-free propyl alcohol wet strength agent purchased from Solvay (Shanghai) Chemical Co., Ltd.

[0038] The ordinary wet strength agent used in the present application is purchased from Mudanjiang Xinxing Chemical Factory.

[0039] In addition, the mixed system of step (2) in all the following examples refers to the mixture formed by mixing the pulp and all the additives.

[0040] In the description of the present application, it should be noted that the specific conditions not mentioned in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased on the market.

[0041] The application will be further described in conjunction with the specific embodiments to help the skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solutions of the application. The protection scope of the application includes but is not limited to the following embodiments, and any modification made to the details and forms of the technical solutions of the application without departing from the spirit and scope of the present application falls within the protection scope of the application.

[0042] Embodiment 1

[0043] The embodiment provides a preparation method of an environmentally friendly straw paper with hydrophobic and non-lipstick properties, and the specific steps are as follows:

[0044] (1) The bleached conifer pulp and bleached broadleaf pulp raw materials are respectively subjected to beating treatment, the beating consistency is 4.0wt%, the beating degree of the bleached conifer pulp is 35°SR, and the wet weight is 4.5g; the beating degree of the bleached broadleaf pulp is 30°SR, and the wet weight is 1.0g, then the two are mixed according to 32wt% of conifer pulp fibers and 68wt% of broadleaf pulp fibers to obtain a fiber mixture;

[0045] (2) The fiber mixture is fed into a headbox through a pressure screen, a biological wax waterproof system sizing agent is added at the inlet of the pressure screen, and a wet strength agent and an alkyl alkene ketone dimer are added at the outlet of the pressure screen, and the paper web is formed; the additives are composed of 1.2% of an environmentally friendly chlorine-free propyl alcohol wet strength agent, 1.0% of an alkyl alkene ketone dimer and 0.15% of a biological wax waterproof system sizing agent according to the mass percentage in the mixed system;

[0046] (3) After the paper web is formed in step (2), the paper web is subjected to three-stage pressing dehydration and once-drying treatment, the pressing pressures are 80kN / m, 80kN / m and 100kN / m respectively, and the once-drying treatment is sequentially performed through 25 drying cylinders, the temperatures of 1-8# cylinders are controlled to be (65-90)℃, the temperatures of 9-25# cylinders are controlled to be (110-120)℃, and the semi-dry paper sheet with a water content of 5.5% is obtained after the drying treatment;

[0047] (4) The semi-dry paper sheet obtained in step (3) is subjected to one-side surface coating of a sizing system and the other side is coated with water through a sizing machine; the sizing system is prepared by compounding 12wt% of a biological wax waterproof system sizing agent and 3wt% of CMC according to the final concentration, and the sizing system is used in an amount of 10kg / t of paper; the water is used in an amount of 5kg / t of paper;

[0048] (5) The sized paper sheet is subjected to secondary drying treatment, and the secondary drying treatment is performed through 12 drying cylinders, wherein the temperatures of 26-35# cylinders are controlled to be (95-110)℃, and 36-37# cylinders are cold cylinders through which cooling water is passed, and the temperatures are controlled to be (50-55)℃;

[0049] (6) The paper sheet after drying in step (5) is subjected to calendering by a calendering machine with a pressure of 45 kN / m, and then is wound to obtain a hydrophobic and non-lipstick-staining environment-friendly straw paper with a water content of 4.5%. The performance indexes of the hydrophobic and non-lipstick-staining environment-friendly straw paper are shown in Table 1.

[0050] In addition, the straw paper obtained in the present example and Comparative Example 1 is subjected to the following tests:

[0051] 1) Figure 1 The figure shows the hydrophobic state of the straw paper obtained in the present example and Comparative Example 1 after spraying several water droplets. After spraying water droplets for 30 min, the straw paper of the present example is still clearly visible to be condensed into water droplets, while the straw paper of Comparative Example 1 immediately starts to disperse after spraying water droplets, and part of the water droplets are absorbed by the paper to form obvious water stains.

[0052] 2) Figure 2 The figure shows the state of the straw paper obtained in the present example and Comparative Example 1 after unilateral water dripping. The straw paper of Comparative Example 1 is located on the upper side of the figure, and the phenomenon of water droplets hanging on the wall is clearly visible, while the straw paper of the present example immediately falls after contacting with water droplets, and there is no hanging phenomenon.

[0053] 3) Figure 3 The figure shows the state of the straw paper obtained in the present example and Comparative Example 1 after drinking coffee, and the contact time of the straw paper with the coffee liquid is 15 min. The straw paper of Comparative Example 1 is located on the upper side of the figure, and the phenomenon of coffee liquid hanging and dyeing is clearly visible, while the straw paper of the present example shows a slight light brown color, and there is no obvious dyeing and hanging phenomenon.

[0054] 4) Figure 4 The figure shows the state of the straw paper obtained in the present example and Comparative Example 1 after drinking cola, and the contact time of the straw paper with the cola liquid is 15 min. The straw paper of Comparative Example 1 is located on the upper side of the figure, and the phenomenon of cola liquid hanging and dyeing is clearly visible, while the straw paper of the present example shows a slight light brown color, and there is no obvious dyeing and hanging phenomenon.

[0055] Example 2

[0056] The present example provides a preparation method of a hydrophobic and non-lipstick-staining environment-friendly straw paper, and the specific steps are as follows:

[0057] (1) The bleached coniferous pulp and bleached broad-leaved pulp raw materials are subjected to beating treatment respectively, the beating concentration is 4.0 wt%, the beating degree of the bleached coniferous pulp is 38°SR, and the wet weight is 4.5 g; the beating degree of the bleached broad-leaved pulp is 35°SR, and the wet weight is 1.0 g, then the two are mixed according to the coniferous pulp fibers accounting for 25 wt% and the broad-leaved pulp fibers accounting for 75 wt% to obtain a fiber mixture;

[0058] (2) The fiber mixture is passed through a pressure screen into a headbox, a biological wax waterproof system sizing agent is added at the inlet of the pressure screen, or a biological wax waterproof system sizing agent is added at the inlet of the pressure screen and a wet strength agent and an alkyl alkene ketone dimer are added at the outlet of the pressure screen, and a wire forming process is performed; the additives are composed of 1.2% of an environmentally friendly chlorine-free propyl alcohol wet strength agent, 1.0% of an alkyl alkene ketone dimer, and 0.15% of a biological wax waterproof system sizing agent according to their mass percentages in the mixed system, and a wire forming process is performed;

[0059] (3) After the wire forming in step (2), a three-stage press dewatering and a first drying process are performed, the press pressures are 80 kN / m, 80 kN / m, and 100 kN / m respectively, and the first drying process is performed through 25 drying cylinders in turn, the temperatures of 1-8# cylinders are controlled at (65-90) °C, the temperatures of 9-25# cylinders are controlled at (110-120) °C, and a semi-dry paper sheet with a water content of 5.5% is obtained after the drying process;

[0060] (4) The semi-dry paper sheet obtained in step (3) is subjected to one-side surface coating of a sizing system and the other side is coated with water by a sizing machine; the sizing system is prepared by compounding 12 wt% of a biological wax waterproof system sizing agent and 3 wt% of CMC according to the final concentration, and the sizing system is used in an amount of 15 kg / t of paper; the water is used in an amount of 8 kg / t of paper;

[0061] (5) The sized paper sheet is subjected to a second drying process, and the second drying process is performed through 12 drying cylinders, in which the temperatures of 26-35# cylinders are controlled at (95-110) °C, and 36-37# cylinders are cold cylinders through which cooling water is passed and the temperatures are controlled at (50-55) °C;

[0062] (6) The paper sheet after the drying in step (5) is subjected to calendering by a calendering machine, the pressure of the calendering machine is 45 kN / m, and then a hydrophobic non-lipstick performance environmentally friendly straw paper is obtained with a water content of 4.8%. The performance indexes of the hydrophobic non-lipstick performance environmentally friendly straw paper are shown in Table 1.

[0063] Example 3

[0064] The difference between Example 3 and Example 1 is that in step 2, a biological wax waterproof system sizing agent and a biological polysaccharide antibacterial agent are added at the inlet of the pressure screen, and the addition amount of the biological polysaccharide antibacterial agent is 0.4%. The water content of the final obtained straw paper is 4.1%.

[0065] Example 4

[0066] The difference between Example 4 and Example 1 is that in step (2), the addition amount of the biological wax waterproof system sizing agent is 0.12%. The water content of the final obtained straw paper is 4.3%.

[0067] Example 5

[0068] The difference between Example 1 and Example 2 is that in step (2), the amount of bio-wax water-proof system sizing agent is 0.20%. The final obtained straw paper moisture content is 4.4%.

[0069] Example 6

[0070] The difference between Example 1 and Example 6 is that in step (4), the proportion of bio-wax water-proof system sizing agent in the sizing system is 11%. The final obtained straw paper moisture content is 4.5%.

[0071] Example 7

[0072] The difference between Example 1 and Example 7 is that in step (4), the proportion of bio-wax water-proof system sizing agent in the sizing system is 13%. The final obtained straw paper moisture content is 4.5%.

[0073] Example 8

[0074] The difference between Example 3 and Example 8 is that in step (2), the amount of bio-wax water-proof system sizing agent is 0.12%. The final obtained straw paper moisture content is 4.2%.

[0075] Example 9

[0076] The difference between Example 3 and Example 9 is that in step (2), the amount of bio-wax water-proof system sizing agent is 0.20%. The final obtained straw paper moisture content is 4.9%.

[0077] Example 10

[0078] The difference between Example 1 and Example 10 is that in step (4), the proportion of CMC in the sizing system is 2%. The final obtained straw paper moisture content is 4.5%.

[0079] Example 11

[0080] The difference between Example 1 and Example 11 is that in step (4), the proportion of CMC in the sizing system is 4%. The final obtained straw paper moisture content is 4.7%.

[0081] Example 12

[0082] The difference between Example 3 and Example 12 is that in step (4), the proportion of CMC in the sizing system is 2%. The final obtained straw paper moisture content is 4.3%.

[0083] Example 13

[0084] The difference between Example 3 and Example 13 is that in step (4), the proportion of CMC in the sizing system is 4%. The final obtained straw paper moisture content is 4.5%.

[0085] Comparative Example 1

[0086] The embodiment provides a preparation method of environment-friendly straw paper, and the process is a process adopted by the inventors in the initial exploration and passed the trial production operation, and the specific steps are as follows:

[0087] (1) The bleached coniferous pulp and the bleached broadleaf pulp are respectively subjected to beating treatment, the beating concentration is 4.0 wt%, the beating degree of the bleached coniferous pulp is 35°SR, and the wet weight is 4.5 g; the beating degree of the bleached broadleaf pulp is 30°SR, and the wet weight is 1.0 g, the mixed fiber raw material is composed of 32 wt% of coniferous pulp fibers and 68 wt% of broadleaf pulp fibers;

[0088] (2) After the mixed fiber raw material obtained in step (1) is uniformly mixed, the mixed fiber raw material is fed into a headbox through a pressure screen, an additive is added at the inlet of the pressure screen, the additive is an environment-friendly chlorine-free propyl alcohol wet strength agent and an alkyl alkene ketone dimer, and the additive is composed of 1.2% of the environment-friendly chlorine-free propyl alcohol wet strength agent and 1.5% of the alkyl alkene ketone dimer in terms of mass concentration, and web forming treatment is performed;

[0089] (3) After web forming treatment in step (2), three-stage pressing dehydration and first drying treatment are performed, the pressing pressures are 80 kN / m, 90 kN / m and 100 kN / m respectively, the first drying treatment is sequentially performed through 20 drying cylinders, and the temperature is controlled to be (90-120) °C, and after the drying treatment, a semi-dry paper sheet with a water content of 5.5% is obtained;

[0090] (4) The semi-dry paper sheet obtained in step (3) is subjected to double-side surface sizing through a sizing machine, the sizing agent is prepared by compounding 12 wt% of alkyl alkene ketone dimers and 3 wt% of CMC according to the final concentration, and the sizing agent is 10 kg / t of paper;

[0091] (5) The sized paper sheet is subjected to secondary drying treatment, the secondary drying treatment is performed through 12 drying cylinders, and the temperature is controlled to be (95-110) °C;

[0092] (6) The paper sheet after drying in step (5) is subjected to calendering through a calendering machine, the pressure of the calendering machine is 45 kN / m, and then the environment-friendly straw paper with a water content of 4.5% is obtained.

[0093] Comparative Example 2

[0094] The comparative example provides a preparation method of environment-friendly straw paper, and the difference from the embodiment 1 is that steps (2) and (4) are different, and the other steps are the same as those in the embodiment 1, wherein the step (2) in the comparative example is as follows:

[0095] (2) The fiber mixture obtained in step (1) is mixed evenly and then passed through a pressure screen into a headbox. Additives are added at the inlet of the pressure screen. The additives are an environmentally friendly chlorine-free propyl alcohol wet strength agent, an alkyl alkenone dimer, and a biological wax waterproof system sizing agent. The mass concentration of the additives is 1.2% of the environmentally friendly chlorine-free propyl alcohol wet strength agent, 1.0% of the alkyl alkenone dimer, and 0.15% of the biological wax waterproof system sizing agent. The mixture is subjected to a wire forming process. The final straw paper has a water content of 4.9%.

[0096] Step (4) is the same as step (4) of Comparative Example 1.

[0097] Comparative Example 3

[0098] This comparative example provides a method for preparing an environmentally friendly straw paper with hydrophobic and non-stick lip properties. The difference from Comparative Example 1 is that a common commercially available wet strength agent is used in step (2). The final straw paper has a water content of 4.6%.

[0099] Comparative Example 4

[0100] The difference from Example 1 is that in step (4), the proportion of the biological wax waterproof system sizing agent in the sizing system is 10%. The final straw paper has a water content of 4.5%.

[0101] Comparative Example 5

[0102] The difference from Example 1 is that in step (4), the proportion of the biological wax waterproof system sizing agent in the sizing system is 14%. The final straw paper has a water content of 4.5%.

[0103] Comparative Example 6

[0104] The difference from Example 1 is that the sizing system in step (4) does not contain CMC. The final straw paper has a water content of 4.1%.

[0105] Comparative Example 7

[0106] The difference from Comparative Example 3 is that a biological polysaccharide antibacterial agent is added to the sizing system in step (4), and the mass percentage of the biological polysaccharide antibacterial agent in the sizing system is 4wt%. The other steps are the same as in Comparative Example 3. The final straw paper has a water content of 4.1%.

[0107] Comparative Example 8

[0108] The difference from Example 3 is that the biological polysaccharide antibacterial agent is added at the outlet of the pressure screen in step (2), after the wet strength agent and the alkyl alkenone dimer. The final straw paper has a water content of 4.6%.

[0109] Comparative Example 9

[0110] The difference between the example 1 and the comparative example 1 is that the proportion of CMC in the sizing system is 1% in step (4). The moisture content of the final obtained straw paper is 4.5%.

[0111] Comparative example 10

[0112] The difference between the example 1 and the comparative example 1 is that the proportion of CMC in the sizing system is 5% in step (4). The moisture content of the final obtained straw paper is 4.8%.

[0113] The above examples and comparative examples are all processes that the inventors have experimented in the research and development process. The examples and comparative examples are far from limited to this. Finally, after a series of optimizations, the preparation process of the straw paper of the present application is obtained. The examples and comparative examples are only for detailed description of the technical content and technical effects of the present application, and are not intended to limit any link of the process. Therefore, it is stated.

[0114] The following are the results of the tests conducted on examples 1-13 and comparative examples 1-12, wherein the test methods refer to the following standards:

[0115] 1) Basis weight (GB / T 451.2-2023)

[0116] 2) Thickness (GB / T 451.3-2002)

[0117] 3) Longitudinal wet tensile strength (GB / T 465.2-2008)

[0118] 4) Hydrophobicity (dynamic contact angle (0.1S)) (YC / T 424-2011)

[0119] 5) 1,3-DCP and 3-MCPD content (GB406.8-2022)

[0120] 6) Cobb value (60S) (GB / T 1540-2002)

[0121] 7) PFAS content (EN 17681-1:2022 and EN 17681-2:2022)

[0122] 8) Mineral oil content (SN / T 4895-2017)

[0123] 9) Biodegradation percentage after 90 days of composting (ISO 14855:2012)

[0124] 10) Final biodegradation percentage (ISO 14855:2012)

[0125] 11) Bacteriostatic rate test (GBIT 20944.3-2008)

[0126] The test results are shown in Tables 1 and 2:

[0127] Table 1 Performance indicators of the antibacterial environment-friendly straw paper of Examples 1-13

[0128]

[0129] Table 2 Performance indicators of the straw paper of Comparative Examples 1-10

[0130]

[0131]

[0132] As can be seen from the data in Tables 1 and 2, the hydrophobic side dynamic contact angle (0.1S) of Examples 1-13 is higher than 110°, and the highest is 136° (Example 5), and the Cobb value (60S) is generally lower than 10 g / m 2 , indicating that the paper has strong hydrophobicity and liquid penetration resistance. And the longitudinal wet tensile strength of all examples is between 0.62-0.77 KN / m, harmful substances such as 1,3-DCP, 3-MCPD, PFAS, mineral oil in all examples are not detected or have very low content, the biodegradation rate after 90 days of composting is more than 70%, and the final biodegradation rate is more than 99%. In addition, the antibacterial rate of examples (such as 3, 8, 9, 12, 13) with the addition of biological polysaccharide antibacterial agent to coliform bacteria, Staphylococcus aureus, Bacillus subtilis and mold is more than 90%, showing strong antibacterial ability. The contact angle of straw paper in Comparative Examples 1-3 without using biological wax waterproof system or using ordinary wet strength agent is less than 100°, and the Cobb value is as high as 20 g / m 2 The above, the hydrophobic performance is obviously worse, the antibacterial property and the degradation property are significantly worse than the examples of the application. In addition, it can be seen from Comparative Example 6 that the straw paper of Comparative Example 6 has high hydrophobic angle, but the Cobb value is also high, which shows that the addition of CMC is crucial to form a complete glue film and improve the adhesion. Comparative Examples 7-8 also show that the addition position of the antibacterial agent seriously affects the overall antibacterial effect. In summary, the present application successfully prepares a kind of straw paper with excellent hydrophobicity, high strength, high antibacterial property, complete biodegradability, non-toxic and environmental protection by optimizing the pulp additive system, sizing formula, pressing and drying process. Its comprehensive performance is significantly better than that of traditional straw paper, and it is suitable for food contact occasions, has good market application prospect and environmental protection value.

[0133] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing environmentally friendly straw paper with hydrophobic and non-sticky properties, characterized in that, The preparation method includes the following steps: Step 1: Pulping bleached softwood pulp and bleached hardwood pulp separately, and then mixing them according to the following weight percentage composition: softwood pulp fiber (25-45)% and hardwood pulp fiber (55-75)% to obtain fiber blend; Step 2: The fiber mixture is fed into the headbox through a pressure screen. Bio-wax waterproofing system sizing agent is added at the inlet of the pressure screen, or bio-wax waterproofing system sizing agent and antibacterial agent are added at the inlet of the pressure screen. Wet strength agent and alkyl ketone dimer are added at the outlet of the pressure screen for web forming. Step 3: After the pulp has been formed on the wire, it is dewatered by pressing and dried once to obtain a semi-dry paper sheet with a moisture content of (5.5-6.5)%. Step 4: Apply a surface coating of the semi-dry paper using a sizing system containing a bio-wax waterproofing sizing agent. Step 5: The paper sheet with surface coating and sizing undergoes a second drying process. Step 6: Calender and roll the paper sheets after the secondary drying process to obtain the environmentally friendly straw paper.

2. The preparation method according to claim 1, characterized in that, In step 1, the control parameters for pulping the two types of wood pulp raw materials are as follows: pulping concentration is (3.8-4.0)%, the freeness / wet weight of bleached softwood pulp is (35-40)°SR / (3.5-4.5)g, and the freeness / wet weight of bleached hardwood pulp is (30-35)°SR / (1.0-3.0)g.

3. The preparation method according to claim 1, characterized in that, In step 2, the additives are composed of the following mass percentages in the mixed system: bio-wax waterproofing system sizing agent (0.12-0.2)%, antibacterial agent (0.3-0.5)%, wet strength agent (0.9-1.2)%, and alkyl ketene dimer (1.0-1.2)%; preferably, the antibacterial agent is a bio-polysaccharide antibacterial agent; and the wet strength agent is an environmentally friendly, chloropropanol-free wet strength agent.

4. The preparation method according to claim 1, characterized in that, In step 3, the control conditions for press dewatering are as follows: three-stage press dewatering is adopted, and the press pressure is set to 80KN / m, 80KN / m and 100KN / m in sequence; and / or, the control process of the primary drying treatment is as follows: the paper sheet after press dewatering is passed through 24 to 26 drying cylinders in sequence, wherein the temperature of the first 7 to 9 drying cylinders is controlled at (65 to 90)℃, and the temperature of the last 16 to 18 drying cylinders is controlled at (110 to 120)℃.

5. The preparation method according to claim 1, characterized in that, In step 4, the semi-dry paper is coated with sizing agent containing bio-wax waterproofing system on one side and water is applied to the other side.

6. The preparation method according to claim 5, characterized in that, The amount of the sizing system containing the bio-wax waterproofing system sizing agent is (10-15) kg / t of environmentally friendly straw paper, and the amount of water is (5-8) kg / t of environmentally friendly straw paper.

7. The preparation method according to claim 5 or 6, characterized in that, The sizing system containing the bio-wax waterproofing system sizing agent is a solution prepared by compounding the bio-wax waterproofing system sizing agent and sodium carboxymethyl cellulose; preferably, in the sizing system, the bio-wax waterproofing system sizing agent has a mass percentage content of (11-13)%, the sodium carboxymethyl cellulose has a mass percentage content of (2-4) wt%, and the solvent is water.

8. The preparation method according to claim 1, characterized in that, In step 5, the secondary drying process is controlled as follows: the paper sheet with surface coating and sizing is dried sequentially through 11 to 13 drying cylinders, wherein the temperature of the first 9 to 11 drying cylinders is controlled at (80 to 120)℃, and the temperature of the last 1 to 3 drying cylinders is controlled at (45 to 65)℃.

9. An environmentally friendly straw paper with hydrophobic and non-sticky properties obtained by the preparation method according to any one of claims 1 to 8.

10. The environmentally friendly straw paper according to claim 9, characterized in that, The environmentally friendly straw paper has a moisture content of (4.0–5.0)%, a longitudinal wet tensile strength of 0.6–1.0 kN / m, a hydrophobic side dynamic contact angle (0.1 s) of 95–140°, and a hydrophobic side Cobb value (60 s) of 7.0–22.0 g / m. 2 .

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