Preparation method of environment-friendly paper clothes rack

Abstract

The application discloses a preparation method of an environment-friendly paper clothes hanger, and belongs to the technical field of paper pulp molding products and waste resource utilization. The method uses sugar cane residue, a by-product of sugar industry, as raw material, and obtains paper pulp through the following steps: cleaning and dust removing, cooking or alkali chemical treatment for pulping, and grinding. After adding waterproof agent and reinforcing agent into the pulp and adjusting the concentration, the pulp is injected into a clothes hanger mold, a wet blank is prepared through vacuum dewatering and / or hot-pressing forming, and then drying and setting are performed to obtain the environment-friendly paper clothes hanger. The method uses the sugar cane residue to replace wood, realizes waste resource utilization, and the prepared clothes hanger has good strength and moisture-proof performance and can be biodegraded after being discarded.

Description

Technical Field

[0001] This invention relates to the field of pulp molding products and waste resource utilization technology, and more specifically to a method for preparing an environmentally friendly paper clothes hanger. Background Technology

[0002] Clothes hangers are widely used in daily life for hanging, drying, and displaying clothing. Currently, the most common types of clothes hangers on the market are plastic hangers, wooden hangers, and metal hangers.

[0003] Plastic clothes hangers are typically made from petroleum-based plastics such as polypropylene (PP), polystyrene (PS), or acrylonitrile-butadiene-styrene copolymer (ABS) through injection molding. These plastic hangers are difficult to degrade in the natural environment after disposal, and long-term accumulation can cause white pollution; incineration may release harmful gases. While wooden hangers are naturally biodegradable, their production consumes large amounts of wood resources, putting pressure on forest conservation. Metal hangers suffer from problems such as rusting, heavy weight, and high cost. Therefore, developing an environmentally friendly clothes hanger that utilizes renewable resources and is completely biodegradable after disposal is of significant practical importance.

[0004] In recent years, paper hangers have been produced through processes such as waste paper recycling, pulping, molding, and drying. However, these existing technologies still have the following shortcomings: Firstly, the source of raw materials is limited. Currently, most paper hangers use waste paper pulp or virgin wood pulp as fiber raw materials. Waste paper pulp has highly variable quality, contains impurities such as ink and adhesives, has complex processing procedures, and the fiber length shortens after multiple recycling processes, leading to a decrease in product strength. While virgin wood pulp has better fiber quality, it is more expensive and does not align with the environmental trend of conserving wood resources.

[0005] Secondly, its moisture-proof performance is insufficient. The surface of pulp fibers contains a large number of hydrophilic hydroxyl groups, making pulp molded products highly susceptible to absorbing moisture in humid environments. This leads to the breakdown of hydrogen bonds between fibers, causing the products to soften, deform, and even lose their load-bearing capacity. Although this can be improved by adding waterproofing agents to the pulp, the bonding effect between the waterproofing agents and the fibers, as well as their retention rate during the molding process, are often not ideal in existing technologies, resulting in limited moisture-proof performance.

[0006] Thirdly, there is a conflict between strength and practicality. Ordinary pulp molded products (such as egg cartons and industrial packaging liners) have relatively low strength requirements. However, clothes hangers are functional load-bearing products that need sufficient bending strength and rigidity to support the weight of clothing without deformation or breakage. To improve strength, existing pulp clothes hangers often require increased product thickness and density, which leads to increased weight, increased raw material consumption, and higher drying energy consumption.

[0007] Sugarcane bagasse is a major byproduct of the sugarcane sugar industry, producing approximately 2-3 tons of water-containing bagasse for every ton of sugar produced. my country has a huge annual sugarcane output, resulting in a concentrated and substantial source of bagasse. Rich in cellulose (approximately 40%-50%), hemicellulose (approximately 25%-30%), and lignin (approximately 18%-22%), bagasse has potential as a raw material for papermaking and molding fibers. However, currently, a large amount of bagasse is directly used as boiler fuel in sugar mills, resulting in low combustion efficiency and low resource utilization. A small portion is used for papermaking or furfural production, but the overall utilization rate still has significant room for improvement. If bagasse could be used as a fiber raw material to manufacture clothes hangers, it would not only reduce raw material costs but also achieve high-value utilization of waste, yielding significant economic and environmental benefits.

[0008] In summary, developing an environmentally friendly paper clothes hanger that combines good mechanical strength, excellent moisture resistance, and complete biodegradability using sugarcane bagasse as raw material and through reasonable additive formulation and molding process is a technical problem that needs to be solved. Summary of the Invention

[0009] In view of this, the present invention provides a method for preparing an environmentally friendly paper clothes hanger.

[0010] To achieve the above objectives, the present invention provides the following technical solution, comprising the following steps: (1) Preparation: Collect sugarcane bagasse, and remove impurities by washing and dust removal; (2) Pulping: The washed sugarcane bagasse is cooked or chemically treated with alkali to separate the fibers, and then milled to obtain pulp; (3) Pulp preparation: Add waterproofing agent and reinforcing agent to the obtained pulp and adjust the pulp concentration; (4) Molding: The slurry of the adjusted concentration is injected into the hanger mold, and the wet blank is obtained by vacuum dehydration and / or hot pressing. (5) Drying: The wet blank is dried and shaped to obtain an environmentally friendly paper clothes hanger.

[0011] Preferably, in the above-mentioned method for preparing an environmentally friendly paper hanger, in step (2), the cooking or alkaline chemical treatment uses sodium hydroxide or potassium hydroxide solution, the treatment temperature is 100-150℃, and the treatment time is 0.5-3 hours; the freeness of the pulp obtained after pulping is 20-40°SR.

[0012] Preferably, in the above-mentioned method for preparing an environmentally friendly paper hanger, in step (3), the waterproofing agent is at least one of alkyl ketene dimer, paraffin emulsion, and rosin glue, and the amount added is 0.5% to 3% of the dry pulp mass; the reinforcing agent is at least one of cationic starch, polyacrylamide, and carboxymethyl cellulose, and the amount added is 1% to 5% of the dry pulp mass; the pulp concentration is adjusted to a mass concentration of 2% to 6%.

[0013] Preferably, in the above-mentioned method for preparing an environmentally friendly paper hanger, in step (4), the vacuum degree of the vacuum dehydration is -0.02 to -0.08 MPa; the temperature of the hot pressing is 150 to 200°C, the pressure is 1 to 5 MPa, and the holding time is 30 to 120 seconds.

[0014] In step (5), the drying is performed by hot pressing at a temperature of 100-180°C and a pressure of 1-5 MPa; or by using a tunnel dryer at a temperature of 120-160°C and a time of 20-60 minutes.

[0015] As can be seen from the above technical solution, compared with the prior art, this invention discloses a method for preparing an environmentally friendly paper hanger. It utilizes sugarcane bagasse, a byproduct of the sugar industry, as the fiber raw material, reducing wood consumption, realizing the resource utilization of waste, and ensuring the product is completely biodegradable after disposal. By simultaneously adding a waterproofing agent and a reinforcing agent to the pulp, and combining vacuum dehydration with hot-pressing integrated molding, dense hydrogen bonds are formed between the fibers, and the additives are uniformly retained, resulting in a hanger with a static load-bearing capacity of over 5 kg. After modification with a waterproofing agent, the hanger maintains its rigidity in humid environments, is not easily softened or deformed, and exhibits excellent moisture-proof performance. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] The bagasse used in this invention is derived from the fibrous waste residue left after sugarcane has been pressed to extract juice in sugar factories. The main components of this bagasse are approximately 40%–50% cellulose, approximately 25%–30% hemicellulose, and approximately 18%–22% lignin.

[0018] Example 1 (1) Preparation: Take 100 kg of fresh sugarcane bagasse that has not been fermented after sugar extraction. First, wash it three times with high-pressure water to remove the mud and sand and residual sugar liquid attached to the surface. Then send it into a cyclone dust collector to further remove heavy impurities such as fine sand and dust under the action of air separation to obtain clean sugarcane bagasse for use.

[0019] (2) Pulping: Clean sugarcane bagasse is put into a digester, and a 3% sodium hydroxide solution is added. The solid-liquid ratio is 1:4, and the pulp is cooked at 120°C for 1.5 hours. After cooking, the pulp is repeatedly washed with clean water until the pH of the washing liquid is neutral. Then, a double-disc refiner is used for refining. The disc gap is adjusted until the pulp freeness is measured to be 32°SR, and sugarcane bagasse pulp is obtained. After dewatering, it is ready for use.

[0020] (3) Pulp preparation: Take 50 kg of the above-mentioned oven-dry pulp, dilute it with water and stir it to make the pulp concentration reach 4%. Under continuous stirring, add 1.5% of the oven-dry pulp mass of alkyl ketone dimer (AKD) waterproofing agent and 2.5% of the oven-dry pulp mass of cationic starch reinforcing agent in sequence, mix them thoroughly and evenly to obtain the pulp to be formed.

[0021] (4) Molding and Drying: The slurry to be molded is quantitatively injected into a metal mold with a hanger-shaped cavity through a slurry injection system. After the mold is closed, it is first dehydrated by vacuuming at -0.06MPa for 10 seconds, and then the hot pressing program is started. Under the condition that the upper and lower molds are heated to 170℃ and pressure of 3.5MPa is applied, the pressure is held for 90 seconds. During this process, the slurry is directly hot-pressed to dry and shape, and a dry environmentally friendly paper hanger blank is obtained when the mold is opened.

[0022] (5) Post-processing and packaging: Remove the small amount of burrs on the edge of the hanger blank, and after passing the visual inspection and load-bearing sampling test, the finished product is obtained and packaged into the warehouse.

[0023] Example 2 (1) Preparation of materials: Same as in Example 1.

[0024] (2) Pulping: Clean sugarcane bagasse was put into the reactor, and a 5% potassium hydroxide solution was added. The solid-liquid ratio was 1:5, and the mixture was cooked at 100°C for 2 hours. The subsequent washing and refining processes were the same as in Example 1, and pulp with a freeness of 28°SR was obtained.

[0025] (3) Pulp preparation: Take the oven-dry pulp and dilute it with water to a mass concentration of 5%. Add 2% paraffin emulsion as a waterproofing agent and 3% polyacrylamide as a reinforcing agent, and stir evenly.

[0026] (4) Molding: Inject the slurry into the mold and use vacuum dehydration molding. The vacuum degree is maintained at -0.04MPa. Continue to pump until the moisture content of the wet blank is about 68%. Open the mold and take out the wet blank.

[0027] (5) Drying: Place the wet blank in a tunnel-type hot air dryer, set the hot air temperature to 150°C, and dry it for 40 minutes in a continuous conveying manner to ensure that the product is thoroughly dried and shaped. Subsequent trimming, inspection, and packaging are the same as in Example 1.

[0028] Comparative Example 1 The steps of this comparative example are basically the same as those of Example 1, except that no waterproofing agent or reinforcing agent is added during the pulp preparation in step (3), that is, only pure sugarcane bagasse pulp is used.

[0029] Comparative Example 2 The steps of this comparative example are basically the same as those of Example 2, except that no waterproofing agent or reinforcing agent is added during the preparation of the slurry in step (3).

[0030] Performance testing The finished clothes hangers obtained in the above embodiments and comparative examples were subjected to the following performance tests according to industry-standard methods, and the results are shown in Table 1: Static load-bearing test: Hang the hanger horizontally and gradually add weights to the hooks and shoulders, and record the maximum load when the hanger breaks or undergoes irreversible deformation.

[0031] Moisture resistance test: Place the clothes hanger in a constant temperature and humidity chamber at 35℃ and 90% relative humidity. After 48 hours, take it out, observe its appearance, and test its load-bearing capacity attenuation.

[0032] Table 1. Results of hanger performance tests As shown in Table 1, the method of this invention, by specifically adding waterproofing agents and reinforcing agents to sugarcane bagasse pulp for modification, and combining it with hot pressing or drying and setting processes, significantly improves the load-bearing strength and moisture resistance of the final clothes hanger, fully meeting daily use needs. In contrast, the control group without added additives has very poor performance and is not practical.

[0033] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0034] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an environmentally friendly paper clothes hanger, characterized in that, Includes the following steps: (1) Preparation: Collect sugarcane bagasse, and remove impurities by washing and dust removal; (2) Pulping: The washed sugarcane bagasse is cooked or chemically treated with alkali to separate the fibers, and then milled to obtain pulp; (3) Pulp preparation: Add waterproofing agent and reinforcing agent to the obtained pulp and adjust the pulp concentration; (4) Molding: The slurry of the adjusted concentration is injected into the hanger mold, and wet blanks are obtained by vacuum dehydration and / or hot pressing. (5) Drying: The wet blank is dried and shaped to obtain an environmentally friendly paper clothes hanger.

2. The method for preparing the environmentally friendly paper clothes hanger according to claim 1, characterized in that, In step (2), the cooking or alkaline chemical treatment uses sodium hydroxide or potassium hydroxide solution, the treatment temperature is 100-150℃, and the treatment time is 0.5-3 hours; the freeness of the pulp obtained after refining is 20-40°SR.

3. The method for preparing the environmentally friendly paper clothes hanger according to claim 1, characterized in that, In step (3), the waterproofing agent is at least one of alkyl ketene dimer, paraffin emulsion, and rosin, and the amount added is 0.5% to 3% of the dry slurry mass; the reinforcing agent is at least one of cationic starch, polyacrylamide, and carboxymethyl cellulose, and the amount added is 1% to 5% of the dry slurry mass; the slurry concentration is adjusted to a mass concentration of 2% to 6%.

4. The method for preparing the environmentally friendly paper clothes hanger according to claim 1, characterized in that, In step (4), the vacuum degree of the vacuum dehydration is -0.02 to -0.08 MPa; the temperature of the hot pressing is 150 to 200°C, the pressure is 1 to 5 MPa, and the holding time is 30 to 120 seconds.

5. The method for preparing the environmentally friendly paper clothes hanger according to claim 1, characterized in that, In step (5), the drying is performed by hot pressing at a temperature of 100-180°C and a pressure of 1-5 MPa; or by using a tunnel dryer at a temperature of 120-160°C and a time of 20-60 minutes.

6. An environmentally friendly paper clothes hanger, characterized in that, Prepared by the method according to any one of claims 1 to 5.

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