Pebble Printing Group is the only company that can develop stone paper machines and help investors sell the raw material to the printing market.
Our Unique Value
Due to stone paper’s fast worldwide growth, millions are being invested in stone paper machines. But many buyers are disappointed by the quality of their stone paper compared to the competitors. Machinery developers are telling buyers anything they want to hear to sell expensive equipment that produces unsellable material. We are familiar with stone paper, from the machines to selling printed products. Our knowledge and network is critical to ensuring success with high-investment stone paper projects.
The Stone Paper Production Process
Raw Materials
Calcium Carbonate (CaCO3)
Calcium carbonate is the main component of stone paper. This compound is one of the most abundant materials on Earth and is commonly harvested from limestone. Stone paper production has certain requirements for the purity of this raw material. The first most relevant qualities of calcium carbonate are the particle size and brightness.
High-Density Polyethylene (HDPE)
High-density polyethylene is a channel 2 recyclable plastic, and one of the most commonly used plastics today. It is used for a number of containers and plastic bags. The current HDPE used for stone paper production is produced via fossil resources. Other than using recycled HDPE, this is the most sustainable configuration for stone paper production. HDPE production currently (2021) consumes less than 0.5% of the world’s annual oil consumption, and this number would decrease with the growth of stone paper in packaging.
Grinding
This step only applies to GCC generated from stone raw material on-site. During this step, the calcium carbonate raw material is reduced to the necessary size for stone paper.
Components
Ball Mill
Granulating
In a high-temperature and high-pressure environment, the calcium carbonate powder, HDPE, and process auxiliaries are homogeneously mixed and pushed through a screw extruder.
Components
Kneader, Twin-Cone Hopper, Twin-Screw Extruder, Single Screw Extruder, Granulator and Separator
Film Blowing
The pellets produced from the granulation process are taken to the film blowing machine, where heat and pressure are applied, melting them together. Air pressure is then applied in an “O” shaped die mould to draw out a blown film. As this film flows from the mould, it is cooled to form a stable cylinder of stone paper. This cylinder is then cut in half and rolled up to produce two rolls of stone paper.
Components
Extruder, O Mould, Membrane Bubble Stabilizer, Forming Splint, Trimming and Winding Machine, Thickness Gauge
Casting
Casting is a small part of the film-blowing process. The sliced half of film is pulled through a T-mould to stretch it and bring it to the required thickness, surface finish, and electrical charge required for rolling.
Components
Extruder, T-Die Head, Thickness Gauge, Trimming and Winding Machine
Rolling
At this step, the film produced from the film blowing and casting processes is stretched between rollers to meet the required thickness of the final stone paper. During this step, the edges of the paper are trimmed to meet the standard roll width.
Components
Mill, Filter, Multi-Roll Calender, Drawing Machine, Cooling and Setting Machine, Trimming Machine, Rewinding Machine
Coating
At this step the base paper is coated according to a proprietary coating recipe using reverse rotary coating and speed differential to ensure homogeneity of the coating. The coating is oven-dried and applied to the backside to secure a double-sided coating of the base paper.
Components
Automatic Uncoiler, Corona Treatment, Coating Head, Oven, Leveling Machine, Rewinding Machine
Packing
Slitting
The slitting machine is controlled by a touch-interface. It’s important here to maintain the tension on the material in order to ensure an efficient coiling of the material without wrinkles. The trimmings are regulated in synchronization with the coiling motors to efficiently utilize the trimmed paper for recycled production.
Cutting
The cutting equipment is also controlled by a touch-screen interface. The length is controlled by a servo-motor and photoelectric sensor to ensure consistent length of cut material. The equipment is tuned to high-precision to ensure consistent cutting length of the material from the roll.
