Pulp molding is a three-dimensional papermaking technology, which means that a certain concentration of pulp is added with appropriate chemical additives in the molding machine to uniformly distribute the fibers on the surface of the mold through vacuum or pressure, so as to make a wet paper mold blank, which is then further dehydrated. Mold, the production technology of drying and shaping the product into a pulp molded product. Products produced from waste paper with different compositions have different properties.
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Therefore, different waste paper or several waste papers can be used in combination according to the purpose of the product to obtain better economic benefits and performance. Pulp molded products can be designed to improve their structure, and various components of materials or surfaces can be specially treated during production to achieve the performance and characteristics required for a certain item or under certain conditions. In addition, the characteristics of the paper molds obtained by different processing methods are different, so changing the processing method or process can improve the performance of the paper mold.
01 Advantage
It has four major advantages: the raw material is waste paper, including board paper, waste carton paper, waste white edge paper, etc., with a wide range of sources; its production process is completed by pulping, adsorption molding, drying and shaping, and other processes, which are not harmful to the environment; It can be recycled and reused; the volume is smaller than foamed plastic, it can be overlapped, and the transportation is convenient. Pulp molding is not only used for lunch boxes and tableware, but also for industrial cushioning packaging. It is currently developing very rapidly.
02 Process flow
pulp paper+water➡milling in the mixing pail➡add related material in mixing pail➡Backflow slurry tank➡product forming➡drying➡Sterilize➡packing
Main process
Pulping
1) Raw materials
a.Fiber that meets hygiene requirements➡Food packaging
b.Waste paper, cardboard➡General packaging
2) Process
Sorting → Breaking → Screening → Refining → Desanding
Blending
The pulping process includes the addition of fillers, pigments, water and oil repellents and other chemical additives, and the pH value and pulp concentration need to be adjusted.
1) Additives
add anti-water,anti-oil material or other material
2) Mixing pulp: pH value 4.5～5.0 Pulp concentration: 1%～2%
forming
The molding process of the pulp molded product is the deposition and filtration dehydration process of the fibers in the pulp on the forming wire mold. According to its molding method, it is divided into the following three types:
1) Vacuum forming method
principle:
The forming mold has a porous structure with a certain mesh forming net attached to the surface. Through vacuum suction, a vacuum is formed in the cavity of the forming mold, the fibers in the pulp are deposited and attached to the surface of the forming mesh, and a large amount of water is taken away during the vacuum suction.
2) Compressed air molding method
principle:
The compressed air molding method is the opposite of the vacuum molding method. Instead of using vacuum suction, compressed air is used as a filter power to accelerate the deposition and dehydration process of pulp fibers on the mesh mold.
3) Extrusion method
principle:
A quantitative amount of pulp is injected into the forming cavity, and the upper forming mold is squeezed downward under pneumatic or hydraulic action, so that the pulp is formed on the net membrane in the forming cavity in a sealed state, and water is discharged from the lower end of the net mold.
press
1) Function:
①Remove most of the moisture from the paper mold.
②The product is further compacted to improve the bonding force between the fibers and increase the strength of the wet paper mold, eliminate the net marks during molding and improve the density and smoothness of the product.
2) Pressing method: ①cold pressing ②hot pressing
dry
After molding and pressing, the dryness of the molded pulp product reaches about 40%, and about 98% of the water has been removed. The excess water needs to be removed by drying, so that the dryness of the product reaches about 97% of the atmospheric balance. Dryness. The drying methods are:
Drying with mold: products are smooth, dense and precise in size and shape
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Demoulding and drying: product shrinkage rate is large, dimensional accuracy is not high
Plastic surgery
The hot pressing method is used to correct the shape of the dried product to make it meet the quality requirements.
Molded dry products do not need to be reshaped.
The mold-relieved and dried product can improve the shape and surface quality of the product due to the shrinkage of the paper mold and the change of the geometric size during the drying process.
Package
After the dried or shaped products undergo quality inspection, they are collected, sorted, stacked, counted, and packaged according to the required quantity to complete the entire production process of the pulp molded product.
03 Causes and countermeasures of waste
Paper mold packaging products are environmentally friendly products that have emerged in recent years. Its main production processes include: beating process, forming process, drying process, and hot pressing and shaping process. In these four major processes, the waste generated by the hot pressing and shaping process accounts for about 80% of the total waste of the entire production line. In response to this phenomenon, talk about the causes and countermeasures of waste products.
1) The surface of the hot-pressing plastic mold made is not smooth and there are many blisters, which affects the quality of the product. Attention should be paid to the purchase of high-quality aluminum materials for sanding, and the finished molds should be smoothed with fine sandpaper.
2) The processed mold has uneven clamping distance between the upper and lower molds, and the product is easy to be scraped when the mold is shaped. The mold should be processed in strict accordance with the specified scale, and the clamping distance between the upper mold and the lower mold should be equal.
3) When installing the mold on the shaping machine, the upper and lower molds are not parallel, causing serious mold rubbing. There should be a dedicated person to install the mold, and it is best to use an instrument to measure whether the upper and lower molds are parallel.
4) The quality of the purchased raw materials is unstable, the shrinkage rate of the product after drying does not match the original juice process, and the scrap rate is high when shaping. It is better to buy corrugated paper edges, gray cardboard and old newspapers cut by a designated carton factory.
5) Improper mixing ratio of beating slurry results in high product damage rate. Different slurry formulas should be selected according to the different paper mold structures.
6) The same set of water molds are used to produce products on different models of molding machines, and there are certain differences between the productions, which leads to an increase in the scrap rate during the subsequent process of reshaping. The water mold should be fixed as far as possible to produce products on the same type of molding machine.
7) The drying product deforms greatly, which affects the overall quality. It should be noted that when people release wet products, they should be careful and grasp the angle of the discharge of different products, and control the drying curve according to different products.
8) The humidity of the molded wet product is not well controlled during drying, resulting in a high rate of plastic waste. The best drying temperature for different products should be mastered, and the humidity of the dried products should generally be 15-18%.
9) A large backlog of products after drying, air-drying for a long time, the product has low moisture content, excessive shrinkage, and high rejection rate during shaping. A long-term backlog of dried products should be avoided, and moisture regain control should be carried out on drier products before reshaping.
10) Insufficient operation experience of shaping workers, inaccurate shaping techniques, and high rejection rate. It is necessary to strengthen business training, continuously improve its work level, and adopt different methods of pressing, pressing, pinching, and pulling on different products to improve product quality.
The global movement toward reducing or banning plastics has gained significant traction. China implemented its first plastic restriction policy in December , limiting the production, sale, and usage of plastic products. Today, over 30 countries and regions worldwide have enacted legislation to control or prohibit plastic in various industries, intensifying efforts year after year.
Pulp molding, made from annual plant fibers through compression molding, has emerged as a popular alternative under these plastic-reduction initiatives. This eco-friendly technology offers the packaging industry a transformative opportunity to adapt to changing environmental policies and market demands.
Rising demand for pulp molded products, especially in tableware, has outpaced production capacity, creating supply shortages.
The industry’s reliance on manual labor limits scalability and increases costs, particularly in regions with higher labor expenses.
Heat and electricity costs account for 20-25% of total production costs, reducing price competitiveness.
Slow technological progress and outdated machinery hinder industry growth. Increased R&D investment is essential for long-term advancement.
A lack of skilled professionals has limited innovation and competitiveness. Developing a talent pipeline is critical to addressing this issue.
Fragmented operations and lack of collaboration among manufacturers result in inefficiencies and higher costs. Creating industry clusters could enhance scalability and competitiveness.
By addressing these challenges and leveraging its inherent advantages, the pulp molding industry is poised for substantial growth as it meets the increasing global demand for sustainable solutions.
Pulp molding offers a transformative solution to global environmental challenges, combining sustainability, versatility, and cost-effectiveness. By leveraging renewable materials and eco-friendly processes, it addresses the growing demand for sustainable alternatives across industries. Despite challenges like energy consumption and labor reliance, continuous innovation and collaboration can propel the industry into a future of widespread adoption and market leadership.
Xiamen Bioleader Environmental Protection Technology Co., Ltd
Professional manufacturer of pulp molding eco-friendly biodegradable tableware and takeaway food packaging! Committed to disposable degradable eco-friendly tableware, we can provide customized pulp sugarcane pulp mold products for a wide range of customers. We have developed hundreds of different products for our customers: meal boxes, plates, bowls, bowl lids, cups, fruit trays, pizza boxes, dessert holders, seafood trays, industrial packaging products, and more. We can customize embossed logos for our guests and welcome contact for more details.
Pulp molding is commonly used to manufacture eco-friendly packaging products like food containers, trays, and protective packaging using recycled or plant-based fibers.
Yes, molded pulp packaging is fully compostable and biodegradable. It breaks down naturally within 60–90 days under proper composting conditions.
Molded pulp is made from renewable fibers like paper or bagasse, whereas plastic is petroleum-based. Pulp decomposes naturally, while plastic may take centuries to degrade.
Absolutely. Molded pulp is widely used for food packaging due to its food-safe certification, heat resistance, and oil/moisture barrier properties without needing plastic coatings.
Molded pulp products are typically made from recycled paper, sugarcane bagasse, bamboo fiber, or wood pulp—all of which are renewable and sustainable raw materials.
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