SPC floor is a new type of environmental protection floor developed based on high technology. It has the characteristics of zero formaldehyde, mould proof, moisture-proof, fireproof, insect proof and simple installation. SPC core flooring factory uses extruder combined with T-shaped mold to extrude PVC substrate, and use three roll, four roll or five roll calender to heat PVC wear-resistant layer, PVC color film and PVC substrate respectively for lamination and embossing at one time. The process is simple and the lamination is completed by heat without glue. SPC core flooring factory uses environmental protection formula, which does not contain heavy metals, phthalates, methanol and other harmful substances. It is widely popular in developed countries in Europe and the United States and the Asia Pacific market.
Main quality requirements of SPC core flooring factory
1. It has lower shrinkage, warpage and better toughness.
2. Ensure that it is not easy to deform in various environments and has good lock pull and certain peeling force between substrate and membrane. Performance mainly depends on the type of material, component processing technology and equipment capacity.
1. Due to the large extrusion volume of SPC floor production line and the need for on-line lamination, the stability of continuous production is very important.
2. Because SPC floor is high filling, screw wear is serious, screw value is relatively high, so we must consider the impact of screw life on the total cost.
3. The floor is thin, the thickness tolerance is small, and the extrusion speed is fast, so it requires good material dispersion, plasticizing performance and fluidity.
1. High wear resistance, relatively low extrusion pressure and better plasticizing screw barrel;
2. The mould with reasonable discharge and uniform discharge is designed;
3. Multi roll calendering system with simple operation and accurate thickness control;
4. The system is accurate and reliable;
5. It has enough cooling space and capacity;
6. Cutting and moving can not have adverse effects on the appearance and warpage of the sheet;
7. SPC core flooring factory selection: not one-sided pursuit of production, but according to their own plate thickness range to choose the size of the machine. 80 / 92 / 110 is suitable for different thickness range of plate production, generally 1:2:1 or 1:3:1 is more reasonable.
Key points of formula
1. PVC resin: five type resin by ethylene method, good strength and toughness, environmental protection.
2. Fineness of calcium powder: because the large proportion of calcium powder directly affects the formulation cost, processing performance, wear of screw barrel and product performance, it is not suitable to choose coarse calcium powder. The fineness of calcium powder should be 400-800 mesh.
3. Internal and external lubrication: considering the long residence time of the material in the extruder at high temperature, the performance of the material and the peeling force, it is recommended to use high-performance wax to control the use of small amount, and use different wax to meet the initial and medium and long-term lubrication requirements.
4. ACR: due to the high content of calcium powder in SPC floor, the plasticization requirements are high. In addition to the control of screw type and processing technology, it is necessary to add additives to help plasticize, and ensure that the melt has a certain strength and ductility in the calendering process.
5. Toughening agent: the floor not only needs low shrinkage and good rigidity, but also needs certain toughness. It needs the balance between rigidity and toughness to ensure the firmness of the lock, not softening at high temperature, and maintaining certain toughness at low temperature. CPE has good toughness, but the rigidity and Vicat softening temperature of PVC are reduced and the shrinkage is increased with the increase of CPE content.
6. Dispersant: due to the large number of components and the large proportion of calcium carbonate, it is very important to moisten and disperse the calcium carbonate. Dispersion can not only improve the processing performance, but also improve the product performance, increase the stripping cycle, reduce and delay the wear of screw barrel.
PE wax is not only a lubricant, but also a dispersing agent. However, the addition of PE wax will affect the balance of internal and external lubrication, decrease the melt strength, increase the shrinkage of the product, reduce the peeling force and make the product brittle. Other dispersants: fluorinated compounds, isocyanate compounds, small dosage, good effect, not only play the role of dispersion, but also coupling lubrication, but the price is high.
7. Return material: try to use the company's production return material and post-processing recovery material.
Note: clean, not wet, batch crushing blending after grinding. In particular, the recycled materials with slitting and slotting must be blended with grinding powder in proportion to form a closed recycling material. It is necessary to adjust the process formula of the sample due to the large variation of the amount of the recycled material.
SPC core flooring factory processing technology and control
1. Formulation and weighing
Different kinds of weight of materials, need to use the corresponding accuracy of the scale, to ensure the weighing accuracy.
Material integration: convenient storage, weighing, circulation and feeding, need to sample and recheck components and accuracy. If it is an automatic weighing system, it also needs to be monitored and rechecked.
2. Mixture storage
Feeding order: determine the feeding order according to the feeding mode.
The automatic feeding and mixing system can be set as follows: filler 90 ℃, treatment agent and PVC resin 95 ℃, stabilizer lubricant 105-110 ℃, processing aid enhancer 115 ℃, return material 120-125 ℃.
Manual feeding: PVC resin + filler + small material + PVC resin + filler + PVC resin + recycle; One time feeding, 120-125 ℃ discharging.
Cold mixing: it must be cooled sufficiently and quickly to prevent material deterioration and be able to cool to 40-45 ℃.
Storage: in order to ensure the uniformity of materials, it is necessary to use a large storage tank for storage and put it aside for a certain period of time before use.
In order to mix the materials which have been put aside for a certain period of time, it is necessary to detect the dry flow of different batches of materials, and detect the rheological properties of logistics, as a monitoring means, and provide the basis for analysis and improvement.
Note that there are differences in mixing effect, mixing temperature and time among different mixers.
3. Extrusion process
The setting of processing technology not only affects the processing level, but also affects the product quality and production efficiency. It needs to be considered in combination with equipment characteristics, material performance and formula.
There is a certain relationship between the size of extruder and the size of product section.
First of all, under a certain extrusion speed of extruder, the production line speed has been very fast, the molding pressure is relatively high, and the requirements for the plasticization and fluidity of materials are high. If the production depends on opening the die gap, the longitudinal tensile ratio is large, and the requirements for the melt strength are high. Moreover, due to the tensile orientation, it is easy to cause a large difference in the longitudinal and transverse shrinkage, resulting in excessive shrinkage and plate warping. At the same time, high speed production also requires high cooling for calendering.
If the 110 / 135 extrusion line is used to produce flooring, the formulation process should be carefully designed and set.
According to the current situation: die gap is slightly greater than the floor thickness.
Fuselage: the temperature of zone 1 and zone 2 is very important, so it is necessary to ensure that the plasticization is convenient for vacuum pumping. If the temperature is too high, it is easy to accumulate materials in the vacuum port, generally between 185-195 ℃, and the others can be slightly lower.
The temperature of the confluence core has a great influence on the back pressure, and a lower temperature is favorable for the melt to change from spiral motion to linear motion, generally at 165-175 ℃.
The mold temperature is relatively higher, which is conducive to the flow of small gap melt. Generally between 190-200 ℃, at the same time, the thickness of the blank should be adjusted according to the die gap.
Extruder host speed: generally controlled at 75-85% of the rated speed. The feeding speed is mainly determined by the rotation speed and load current of the main engine.
Under the premise of formula determination, the processing temperature, host speed and feeding speed match each other, so that the current is stable, the discharge is uniform, the surface has no defects, and the production speed is certain.
In a certain period of time, the screw will wear. First, the processing technology can be adjusted, such as reducing the extrusion speed, increasing the feeding speed, appropriately increasing the processing temperature of the first and second zones, and reducing the temperature of the confluence core. The dosage of ACR was increased by adjusting the formula. If necessary, readjust the gap of screw barrel, polish the damaged part, and then adjust the process formula.
4. Calendering film technology
On the premise of stable extrusion.
Main control: roller clearance, temperature, speed, as well as before and after speed matching.The gap and speed of the first pair of rollers determine the basic thickness of the floor, which should be initially determined according to the linear speed of extrusion. Behind the film covered roller speed is a little faster, to ensure that there is a certain expansion force, does not cause the film stretch narrow is appropriate. Traction speed is so, not to plate deformation. According to the actual situation, some adjustments are slower. Embossing and film sticking mainly depend on the roller gap and roller temperature. Different plate thickness, film type, different gap and temperature are adopted, and the influence of traction speed is considered.
Roll temperature and speed: ensure normal calendering, clear embossing, firm film adhesion, sufficient trimming and no film deformation.
Roller temperature: 165-185 ℃.
The gap between the front and rear rollers is basically the same. The two need to be adjusted together.80 unit 4mm floor reference production process reference:
Hot mixing temperature: 125 ℃
Cold mixing: ≤ 45 ℃
5. Stereotypes and others
As the product in the production process has not been completely finalized, so the cutting flow to avoid stress, bearing the tray needs to be solid and smooth. Product testing also needs to put the substrate and finished products to a certain time for sampling.