Stone paper is made of a large quantity of inorganic minerals (stone powder) and a smaller amount of Resin. It has the same functional properties as wood pulp paper. This stone paper manufacturing process is more environmentally friendly than traditional papermaking. It does not produce harmful waste, such as wastewater or waste gases. Stone paper is 20-30% cheaper than alternative products. It is also extremely competitive and has a very promising market outlook.
This article will describe the raw materials used in stone paper and its manufacturing process to show off its unique benefits compared to other paper products.
Stone Paper Raw Materials Pretreatment and Masterbatch Prepare
As a novel, environmentally friendly paper, stone paper is made primarily from an inorganic powder, with calcium carbide dominating the composition, typically comprising 70% to 80%. To achieve high-quality stone paper production, meticulous raw material pretreatment and the preparation of the crucial intermediate material–masterbatch–are essential.
Masterbatch can be made by modifying organic resins and calcium carbonate powder. It also contains various functional additives. It provides a solid base for the extrusion process.
Composition of the main raw materials in stone paper
1. Limestone (Calcium Carbonate), the core material
Main Component The most important chemical component in limestone is calcium Carbonate (CaCO3). This is the main raw material used for stone paper.
Stone Paper: Calcium Carbonate is added in large amounts to stone paper as a fine Powder. (Particle size should be around 1000 mesh and can even go up to nano-level). This gives stone paper its “stone” characteristics and reduces the dependency on plant fibres and traditional water. It is because of this that the calcium carbonate content in stone paper is higher than that of organic Resin.
2. Talc is a filler that can be used as an auxiliary.
Chemical composition: The main component of talc is hydrous magnesium sulfate (Mg3Si4O10OH)2.
Stone Paper Role: Talc is added to stone paper in small quantities as a functional additive. This helps adjust the smoothness and the whiteness. Talc powder, with a high degree of fineness and whiteness, is used to improve the visual appearance and surface texture of stone paper.
3. Barium Sulfate as a Functional Additive
The chemical formula of barium sulfate (BaSO4) is an inorganic salt. Barium sulfate, which is used in the manufacturing of stone papers to improve printing and optical properties, is the main ingredient.
Adding a suitable amount of barium to the pulp can also improve the printing effect. Barium sulfate also enhances the paper’s whiteness and opacity, making it better for writing and printing.
How do you prepare the masterbatch for stone paper?
In order to prepare the masterbatch, it is necessary to mix the following ingredients in a certain proportion.
- Synthetic Resin: as a matrix material for the masterbatch. This gives the masterbatch the flexibility and processing ability it needs.
- Chemical Additives: including, but not limited to plasticizers and lubricants. Brighteners, stabilizers, and dozens of other additives are also included. Each of these additives has a specific role to play, and they work together in order to optimize processing performance and product quality.
- Inorganic Powder: is mainly calcium carbonate. However, depending on the formula, it may also include talc, wollastonite or zeolite powders, titanium dioxide, or other inorganic particles to adjust the final Performance.
The components are then transformed into a well-performing master batch of stone paper through processes like intensive mixing, extrusion, and granulation. This is the final step in preparing for large-scale production.
Stone Paper Manufacturing Process – How do you make stone paper?
The modern papermaking process includes major steps like pulping, blending and other processing steps. The production of stone papers is completely different and closer to plastic processing. Stone paper is produced using four distinct processes: calendering (casting), biaxial stretching (biaxial stretching), and film blowing.
1. Calendering Method
Process Resin+Masterbatch+Resin – Co-extrusion-Preheating-Stretching-Shaping-Corona Treatment-Coating-Slitting-Width-Winging-Inspection-Finished Product
Advantages:
- Excellent surface and high quality: The paper’s surface is flat, smooth, and of superior quality. It is the preferred method for producing high-quality stone papers.
- Stable Performance, precise thickness: The product’s thickness can be controlled precisely, and its Performance is reliable and stable.
- Wide variety of applications and high automation level: This machine can produce stone papers of different specifications and thicknesses. It is suitable for industrial production at large scales with high automation.
Disadvantages:
- A complex process, high investment costs: The equipment structure is complex, and investment costs are high, particularly for the core equipment calendar.
- Long production process, high energy consumption The production line’s process is long and requires a lot of energy.
2. Casting Method
Process: Mixing of Raw Materials – Intensive mixing and plasticization – Extrusion Granulation (Uniaxial Stretching), Casting Molding, Cooling and Shaping (Optional: Corona treatment – Coating), Slitting, Winding, Inspection and Finished Product
Advantages:
- Combines rigidity and strength in a single sheet.
- Modest process, adjustable thickness: The speed of die extrusion and rotation of the casting roll are different. The meniscus is stretched in a uniform direction between the extruded die and the cooling roller. The synthetic paper thickness can be adjusted to meet various product needs. It is more cost-effective and moderate in terms of equipment and process flow compared to the calendering technique.
Disadvantages:
- Anisotropic Performance The Performance in the longitudinal direction is much better than the Performance in the transverse direction.
- Surface smoothness is slightly inferior: Surface smoothness may be less than the calendering technique. (Compared to the calendering technique)
- Limited width The width can be limited up to a certain degree.
3. Biaxial Stretching Method
Process: Mixing of raw materials – Intensive mixing and plasticization – Extrusion Granulation/Sheet/Film Preheating, Longitudinal Stretching MD & Transverse Stretching TD – Heat setting Cooling and Shaping (Optional) Slitting and Winding (Optional) Inspection & Finished Product
Advantages:
- Excellent Performance The paper is a high-end stone paper with exceptional properties such as strength, rigidity and toughness. Dimensional stability, too, is at the highest level.
- High-grade, Exquisite, and Balanced in All Directions: Both the longitudinal and transverse properties of the paper are well-balanced. The isotropy and surface smoothness is good.
Disadvantages:
- Extremely complex process, extremely high technical difficulty: Largest equipment structure, most complex control system, and extreme difficulty in optimizing parameters and controlling quality.
- High investment, high cost: The equipment investment and production costs are the highest of all processes, which limits their popular application.
- The width of large-width biaxial stretch production lines may still be limited.
4. Film Blowing Method
Process: Mixing of Raw Materials – Intensive mixing and Plasticization (Annular Die Extrusion) – Film Blowing Molding (Bubble Inflation), – Traction – Winding (Optional Slitting)
Advantages:
- Economical and Efficient, Low Investment: High output and high production efficiency with the lowest equipment investment of the four processes.
- Easy to Operate, Simple Process: The equipment is easy to operate and maintain.
- Good Thickness Uniformity, Ideal for Thin Products This product is ideal for thin stone paper products.
Disadvantages:
- Relatively Low Environmental Protection, High Resin Content: A high amount of Resin is used to ensure moulding, but the calcium carbonate content is low. The environmental protection may be slightly less than in other high-filling methods.
- Limited Thickness and Width, Moderate Performance The paper’s performance is moderate and restricted in terms of its width and thickness.
- Surface Smoothness is Slightly Lower: The surface smoothness may be slightly lower than that of the calendering and casting methods.
Stone Paper Manufacturing Process: Advantages
1. Save Wood Resources to Alleviate Wood Scarcity
- No wood needed: The main material used to make stone paper is abundant limestone, which eliminates dependence on wood.
- Relieving Wood Shortages: Traditional papermaking is a major wood consumer. In my country, two-thirds of the industrial wood used is for papermaking. A lack of wood has hampered the papermaking industry. Stone paper is a great alternative to wood.
2. Environmental Protection and Energy Savings, Reducing Emissions
- No wastewater discharge, better for the environment: Traditional papers are made with a lot of wastewater that is difficult to treat and causes pollution. Stone paper production does not use water or bleaching. This eliminates a large amount of sewage generated by traditional papermaking.
- Energy-saving, lower energy consumption: The process of making stone paper is primarily powered by electric energy, and its unit energy consumption rate is significantly lower than that of traditional papermaking. The energy consumption per unit is 2/3 that of conventional papermaking. This significantly reduces energy consumption.
Recommended Stone Paper Production Line
Stone paper has great market potential, as it is a superior product with excellent environmental characteristics. To truly achieve these advantages in high-quality stone paper products and to successfully capture market opportunities, selecting the right production equipment will be crucial.
GSmach Stone Paper Production Line is the best choice for you to seize the market quickly and achieve commercial success.
When you choose GSmach Stone Paper Production Line, you get:
- High capacity and high return: It can meet the market’s demand quickly and offers significant economies of size.
- Excellent quality guarantee: The technology is from China’s top stone paper exporter, and the product is of high quality.
- Comprehensive Support: Online support, on-site installation, and after-sales services to resolve your concerns.
- Energy-saving, space-saving, and efficient: The small footprint, short delivery cycle, and low energy consumption reduce operating costs, allowing for a quick return on investment.
- Leading technology upgrade: The most recently upgraded machine with faster speed, greater capacity and better quality.
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