The classification of raw materials for pulp molding plays a crucial role in producing high-quality disposable tableware and industrial packaging products. This article explores various types of commodity pulp and recycled waste paper, their sources, treatment processes, and compliance with national food safety standards, helping manufacturers optimize material efficiency and product performance.

Classification of raw materials for pulp molding

Commodity pulp board
Commodity pulp used in the production of disposable tableware and high-end industrial packaging products is generally chemical pulp, bio-enzyme pulp or chlorine-free bleached chemical pulp, which can be purchased directly from professional pulp mills. Usually, imported high-grade wood pulp, domestic ordinary wood pulp, bagasse pulp, bamboo pulp, wheat straw pulp, rice straw pulp, reed pulp and selected white paper edges and other short-fiber pulp can be selected according to the performance requirements of the product. Different pulp types are scientifically combined in precise ratios to meet the mechanical, surface, and molding characteristics required by specific products, ensuring both material efficiency and cost reduction.

At present, domestic pulping manufacturers with annual production capacity of more than 100,000 tons and reed, bagasse, bamboo, wheat straw and other grass fibers as the main raw materials have their own pollution control systems. In terms of raw materials, pulp molding production can completely take a path of “centralized pulping and decentralized production”. Not only does it have no environmental pollution obstacles, but it can also obtain more reliable raw material guarantees.

Regardless of the pulping process applied in disposable tableware production, all natural-colored pulp or pulp board must comply with the GB 4806.8-2016 National Food Safety Standard for Food Contact Paper and Paperboard Materials and Products. For bleached pulp or board, compliance with GB 4806.8-2016 is also required, in addition to being bleached without the use of chlorine (i.e., Elemental Chlorine Free, ECF or Totally Chlorine Free, TCF).

2. Waste paper raw materials used in the production of pulp molding industrial packaging products

Waste paper raw materials used in the production of pulp molding industrial packaging products have the characteristics of wide sources, low cost, and sufficient supply. In theory, all recycled waste paper can be used for pulp molding production after proper treatment.

Paper and its products are widely used in various fields such as book printing, daily life, and commodity packaging. Except for some of them that cannot be recycled, such as library books, certain legal texts and company records that need to be preserved for a long time, and some household and medical sanitary paper that is seriously polluted and can only be incinerated to recover heat or composted or landfilled, most of the used paper can be recycled as waste paper. After proper treatment, most of the waste paper can be made into recycled fibers and reused.

1 Recycling of waste paper

With the development of the national economy, the improvement of people’s living standards and the increase in per capita consumption of paper and its products, as well as factors such as waste treatment, environmental factors and consumer demand, the recycling of waste paper has been greatly promoted. The recycling rate of waste paper has gradually increased with the acceleration of urbanization, because it is easier to collect waste paper in a centralized manner in the city, and it can effectively reduce the acquisition cost of waste paper.

There are three main channels for recycling waste paper. The sources of this type of waste paper are: old newspapers, waste books and periodicals, and various types of waste paper that has been typed, copied or written in government offices, schools or residential areas; and various types of packaging paper, cartons, paper boxes and cardboard in stores and supermarkets. Waste recycling companies organize personnel to purchase these locations regularly. In addition, this type of waste paper also includes waste paper collected by individuals and various types of waste paper delivered by residents. This type of waste paper often has many varieties and large quantities, and is one of the main sources of waste paper.

1. Waste paper collected by waste recycling companies
2. Waste paper collected by individuals
   This type of waste paper is waste paper collected by individuals, including garbage and waste paper removed by units during cleaning. Since this type of waste paper is collected by individuals, the quantity is not large and most of it is sold to the collection station of waste recycling companies. The waste paper collected in this way is generally of lower grade.
3. Waste paper within the factory
   In the production process of any type of paper, waste paper is inevitably generated. This type of waste paper is mostly digested and utilized by the factory itself. For some factories that use base paper as raw material to produce coated processed paper, or factories that use base paper as raw material to produce paper products, or factories that use corrugated base paper and cardboard as raw materials to produce cartons, or printing factories that produce waste paper and scraps in the production process, they generally cannot be used by themselves or are inconvenient to use. They can be sent to special waste paper recycling factories for treatment. This part of waste paper is generally clean and uniform in quality, which is convenient for recycling.

2. Sorting of waste paper

The waste paper recycled by the waste paper recycling system is often not a single type, but a mixture of multiple types of waste paper. In order to meet the principle of making the best use of waste paper, it is necessary to classify, store and treat the waste paper according to the types, properties, uses, etc. of waste paper before professional treatment. This is the sorting of waste paper. While sorting waste paper, it is also necessary to select metal, wood chips, sand and gravel, ropes, sticky substances, plastic sheets, hot-melt resins, polyethylene and polystyrene and other impurities in the waste paper to make the waste paper reach a certain purity.

Since the recycled waste paper is in different conditions and has complex components, and contains a wide variety of non-paper components, manual sorting is the best choice. Even if a magnetic separator is used to separate metals and remove heavy impurities by sorting, manual sorting is still required in the end. The sorting of waste paper is usually done by using an inclined conveyor belt equipped with a speed change mechanism, and several people manually remove non-paper materials such as wood, stones, metals, glass, plastics and impurities that are harmful to production beside the conveyor belt. The workload of manual sorting mainly depends on the source of the waste paper and the purpose of the recycled pulp. For example, pre-consumer recyclable paper such as white paper edges and paper flowers from printing plants only requires simple sorting and usually enters the waste paper treatment system after on-site inspection. However, post-consumer recyclable paper, such as waste paper collected from households, must be sorted to ensure different uses of different waste paper. Especially for recycled cultural paper, sorting is particularly necessary for regenerating cultural paper after deinking. Manual sorting of waste paper can be divided into positive sorting and negative sorting. Active sorting is the process of removing non-paper components from the waste paper when it enters the production line, and also separating waste paper according to different qualities so that it can be used with high quality. This sorting technology can produce relatively clean recycled pulp, but the productivity of sorting is very low. Passive sorting mainly separates non-paper components. Although this sorting technology has a high productivity, it leads to a lower quality standard of recycled pulp.

3. Classification of waste paper

The classification of recycled waste paper has a direct impact on the collection, treatment and utilization of waste paper. The sources of waste paper are different, and their fiber types, components and properties vary greatly. Classifying the recycled waste paper can achieve the purpose of graded use and making the best use of it.

Waste paper is typically classified based on its source, collection method, fiber composition, and overall quality. At present, there are two sources of industrial waste paper in my country: one is domestic waste paper, mainly old corrugated boxes, book and magazine paper, old newspapers, scraps from carton factories, white paper trimmings from printing factories, cement bags, mixed waste paper, etc.; the other is imported waste paper, which used to come mainly from the United States, Europe, and Japan. Since 2021, my country has banned the import of foreign waste paper. In order to cope with the shortage of raw materials, leading domestic paper companies have deployed overseas and invested in the construction of waste paper processing and recycled pulp plants in North America and Southeast Asia. By importing recycled pulp, the shortage of pulp raw materials in my country can be alleviated to a certain extent. my country’s recycled waste paper can be roughly divided into the following categories:

1. White waste paper. This type of waste paper can also be regarded as a substitute for pulp, including unprinted white paper with relatively consistent whiteness and no harmful substances. The waste does not exceed 0.5%. After pulping, this type of waste paper can be used as bleached pulp for the production of general writing and printing paper, or used for the manufacture of medium and high-end toilet paper, or used as white pulp in the paper mold industry. This type of waste paper mainly consists of the white paper edges cut off by printing plants.
2. Printed books and magazines waste paper. This category of waste paper includes printed books and magazines collected after distribution. As it contains minimal mechanical pulp, it provides relatively stable fiber quality for pulping applications requiring better strength and cleanliness. This type of waste paper is required to contain no prohibited substances, and the waste content does not exceed 0.25%. After deinking to remove the color and ink, this type of waste paper can be used to produce glossy paper, writing paper, letterpress paper, toilet paper, etc. It can also be used in the paper mold industry to produce paper mold industrial packaging products.
3. Old newsprint. Refers to sorted bundles of used newspapers, excluding magazines and other printed materials. It is primarily composed of high-content mechanical pulp and is commonly used in applications requiring lower fiber strength and high absorbency. The letterpress and color printing parts are not higher than the normal percentage. The packaging must not contain tar and prohibited substances, and the waste content does not exceed 0.25%. After deinking, this type of waste paper is mainly used to make newsprint, or to make household paper and general cultural paper, or to make paper mold industrial packaging products in the paper mold industry.
4. Waste paper from cartons and paperboards. This type of waste paper includes kraft paperboard, corrugated paperboard trimmings, old corrugated paperboard boxes, various waste paper boxes, cartons, yellow, white, and gray paperboards, etc. Prohibited materials are limited to a maximum of 1% by weight, while total allowable waste and non-fiber contaminants must not exceed 5%. This type of waste paper can be used to recycle straw paperboard, tea paperboard, boxboard, corrugated base paper, etc. The bamboo and wood pulp waste paper can be used to produce noodle paperboard, or used in the paper mold industry to produce paper mold industrial packaging products.
5. Paper bag paper waste and kraft paper waste. This type of waste paper refers to broken cement bags, waste kraft paper bags, and other paper bags and kraft paper waste recycled after cement packaging. This type of waste paper is selected after disassembly and does not contain debris. It can be recycled to replace paper bag paper, recycled striped packaging paper, or mixed with wood pulp as boxboard noodle pulp, or used in the paper mold industry to produce paper mold industrial packaging products.
6. Mixed waste paper. This type of waste paper is low-grade waste paper, including some “garbage waste paper” (waste paper collected from garbage dumps). Mainly contains mixed magazines, books, subpoenas, receipt books, exercise books for primary and secondary school students, office waste paper and waste paper after packaging items. The proportion of various waste papers is not limited, and the content of prohibited substances shall not exceed 2%, and the content of waste shall not exceed 1%. This type of waste paper is mainly used to produce roofing paperboard, moisture-proof paperboard and ordinary low-grade paperboard core layer, etc., or used in the paper mold industry to produce low-grade paper mold industrial packaging products. With the modernization of office equipment, the amount of office waste paper (such as used computer printing paper, electrostatic copy paper, fax paper, etc.) will increase year by year. Therefore, mixed office waste paper will become a new type of waste paper. In the pulp molding production process, especially the production of industrial packaging pulp molding products, natural waste paper raw materials are generally used, such as waste cartons and paperboards, paper boxes, paper bags and kraft paper and some mixed waste paper, mainly depending on the quality and performance requirements of the products produced.