SPC floor formulation and physical properties
SPC floor formulation and physical propertiesThe main quality requirements of SPC flooring
No. Item Requirements
1 Thickness deviation ±0.05mm
2 Density 1.9~2.1g/cm³
3 Shrinkage ≦0.1% (80℃ 6 hours)
4 Warpage ≦0.5mm/m
5 Verticality and straightness ≤0.25mm within ≤400mm
Within ≥400mm≤0.35mm
6 Anti-slip index ≥0.30mm
7 Locking clearance ≤0.10mm
8 Pulling force of lock, normal temperature 23℃
5mm＞13-15kgs/5cm
4.2mm＞12kgs/5cm
＞15-18kgs/5cm
(If the short side uses V buckle)
9 Light resistance ≥6
10 Thermal conductivity 0.25 W/(m•℃)
11 Peeling force ≥50N/cm²
SPC floor main performance requirements
1. Has lower shrinkage, warpage and better toughness.
2. To ensure that it is not easy to deform in various environments and has a good pulling force of the lock and a certain peeling force between the substrate and the film. The performance is mainly determined by the ability of the processing equipment of the type of material.
Processing requirements
1. Due to the relatively large extrusion volume of the SPC floor production line and the need for online lamination, the stability of continuous production is very important.
2. Because the SPC floor is highly filled, the screw wear is severe, and the value of the screw is relatively high, so the influence of the life of the screw on the total cost must be considered.
3. The floor is relatively thin, the thickness tolerance requirements are small, and the extrusion speed is fast, so it is required to have better material dispersion, plasticization performance and fluidity.
Processing Equipment
1. High wear resistance, relatively low extrusion pressure and better plasticizing screw barrel
2. Design a mold with reasonable output
3. Multi-roll calendering system with simple operation adjustment and precise thickness control
4. Membrane-guided tension control deviation correction system is accurate and reliable
5. And have enough cooling space and capacity
6. Cutting and moving can not adversely affect the appearance and warpage of the board
7. Manufacturer selection: You can't pursue output unilaterally, but choose the size of the machine according to the thickness range of your own plate. 80/92/110 is suitable for the production of plates of different thickness ranges, and the general configuration of 1:2:1 or 1:3:1 is more reasonable.
(The size of the extruder and the thickness of the plate should be reasonably matched)
Raw materials and formula
No. Name Quantity Remarks
1 PVC five resin 75 Ethylene method
2 Heavy calcium carbonate 225 400~450 mesh
3 Calcium and zinc stabilizer 6.5~8
4 TG-60 0.9-1.8
5 PE wax 1 0.6
6 PE wax 2 0.3~0.5
7 ACR 2.5~4
8 Toughener 4~8
9 Dispersing agent
10 Recycling 30~50
PVC 50 KG
Calcium carbonate 150KG
Calcium zinc stabilizer 3.5- 5KG
Grinding powder (calcium zinc) 50
Stearic acid 0.8
PE wax 0.6
CPE 3
Impact modifier 2.5
Carbon black 0.5
Recipe points
1. PVC resin: It adopts the five-type resin of ethylene method, which has better strength and toughness and is environmentally friendly.
2. The fineness of calcium powder: because the addition ratio is large, it directly affects the formulation cost, processing performance, wear of the screw barrel and product performance, so it is impossible to choose too coarse calcium powder. The fineness of calcium powder is 400-800 mesh. .
3. Internal and external lubrication: Considering the long residence time of the material in the extruder at high temperature, as well as the material performance and peeling force factors, it is recommended to use high-performance wax to control the small amount of use, and use different waxes to meet the initial and mid-long term Lubrication requirements.
4.ACR: Due to the high content of calcium powder in SPC floor and high plasticization requirements, in addition to the control of screw type and processing technology, it is necessary to add plasticizers to help plasticize, and ensure that the melt has a certain strength, and in the calendering process There is a certain ductility.
5. Toughening agent: The floor requires not only low shrinkage and good rigidity, but also certain toughness. The rigidity and toughness need to be balanced to ensure the firmness of the lock. It does not soften at high temperatures and is maintained at low temperatures. Certain toughness. CPE has good toughness, but the addition of a large number of parts reduces the rigidity of PVC, Vicat softens the temperature, and causes the shrinkage rate to increase.
6. Dispersant: Since there are many components and the proportion of calcium carbonate added is relatively large, the infiltration and dispersion treatment of calcium carbonate and the dispersion of each component are very important. Dispersion can not only improve the processing performance but also improve the performance of the product, increase the demoulding cycle, reduce and delay the wear of the screw barrel.
PE wax is not only a lubricant, but also has a dispersing effect, but the amount of addition will affect the balance of internal and external lubrication and the deterioration of melt strength, increase the shrinkage rate of the product and reduce the peel force, and the product becomes brittle.
Environmentally friendly plasticizer: It can play a certain role in dispersion and help plasticize. However, if the amount is too large, it will affect the shrinkage rate. The Vicat temperature of the product will decrease, and the product will become brittle with the use of time.
Other dispersants: fluorinated compounds, isocyanate compounds, small dosage, good effect, not only play the role of dispersion and coupling lubrication, but the price is high.
7. Return material: try to use the company's production return material and post-processing recycled materials.
Note: clean, not damp, crushed and blended in batches, and pulverized. In particular, the slitted and slitted reclaimed materials must be blended in proportion to form a closed recycled material for recycling. Large changes in the amount of regrind need to adjust the recipe of the sample.
Processing technology and control
1. Recipe and weighing
For different types of materials, we need to use weighing instruments with corresponding accuracy to ensure weighing accuracy.
Integration of materials: It is convenient to store weighing and transfer materials, and it is necessary to carry out sampling and review of components and accuracy. If it is an automatic weighing system, it also needs monitoring and review.
2. Mixture storage
Order of feeding: Determine the order of feeding according to the way of feeding.
The automatic feeding and mixing system can be set up 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 + filling material + small material + PVC resin + filling material + PVC resin + return material; one-time feeding, 120-125 ℃ discharge.
Cold mixing: must be fully and quickly cooled to prevent the material from deteriorating, and has the ability to cool to 40-45℃.
Storage: In order to ensure the uniformity of the material, it is necessary to use a large storage tank to store and leave it for a certain period of time before use.
To mix materials that have been put on hold for a certain period of time, it is necessary to detect the dry flow of different batches of materials and the rheological properties of the logistics, as a monitoring method, and provide a basis for analysis and improvement.
Note that there are differences in mixing effect between different mixers, and differences in mixing temperature and time.
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 comprehensively considered in combination with equipment characteristics, material properties and formulations.
The relationship between the size of the extruder and the product specifications:
There is a certain relationship between the size of the extruder and the cross-sectional size of the product.
For example, the 110 extruder is difficult to make a 4mm thick plate. First of all, at a certain extrusion speed of a large extruder, the production line speed is already very fast, the molding pressure is relatively high, and the plasticization and fluidity requirements of the material are high. If the production is made by opening a large die gap, the longitudinal stretching is relatively large. The requirements for melt strength are high, and due to the tensile orientation, it is easy to cause a large difference between the longitudinal and longitudinal shrinkage rates, causing excessive shrinkage and warpage of the sheet. At the same time, high-speed production has high requirements for calendering and cooling.
If the 110-extrusion production line is used to produce flooring, the formulation process should be carefully designed and set up.
According to the current situation: 92 and 80 units are more suitable for floor under 4mm. The die gap is slightly larger than the floor thickness.
Body: The temperature in zone 1 and zone 2 is very important. It is necessary to ensure that the plasticization is easy to evacuate. Too high, easy to accumulate material in the vacuum port, generally between 185-195, other can be slightly lower.
The temperature of the confluence core has a great influence on the back pressure. A lower temperature is beneficial for the melt to change from spiral movement to linear movement, generally at 165-175°C.
The temperature of the mold is relatively higher, which is conducive to the flow of the melt with a small gap. Generally, it is between 190-200°C, and the thickness of the blank is adjusted uniformly according to the mold gap.
The speed of the main machine of the extruder: generally controlled at 75-85% of the rated speed. The feeding speed is mainly determined by the rotation speed of the host and the current of the host (load).
Under the premise that the formula is determined, the processing temperature, the speed of the host machine, and the feeding speed match each other, so that the current is stable, the discharge is uniform, the surface is free of defects, and there is a certain production speed.
The screw will wear during a certain period of time. First, the processing technology can be adjusted, such as reducing the extrusion speed, increasing the feeding speed, and appropriately increasing the processing temperature in the first and second zones to reduce the temperature of the confluent core. Properly adjust the formula to increase the amount of ACR. If necessary, readjust the clearance of the screw barrel, polish and polish the damaged parts, and then adjust the process formula.
4. Calendering process
Under the premise of stable extrusion.
Main control: matching of roller gap, temperature, speed, and front and back speed.
The gap and speed of the first pair of rollers determine the basic thickness of the floor and should be preliminarily determined according to the linear speed of extrusion. The speed of the roller behind the film is slightly faster to ensure that there is a certain expansion force, and it is appropriate not to cause the film to be narrowed. This is true for the traction speed, so that the sheet does not deform. Some adjustments are slower according to the actual situation. Embossing and filming are mainly determined by the roller gap and roller temperature. Different sheet thicknesses and film types use different gaps and temperatures, and consider the influence of traction speed.
Roller gentle speed: It should be ensured that the calendering is normal, the embossing is clear, the film is firmly bonded, the trimming is sufficient, and the film is not deformed.
Roller temperature: generally 165-185℃.
The gap between the two pairs of rollers is basically the same. The two need to be adjusted together.
Reference production process of 80mm 4mm floor reference:
Hot mixing: 125℃ Cold mixing: ≦45℃
Die gap: slightly smaller in the middle of 3.8～4.0
body:
Area 1 Area 2 Area 3 Area 4 Area 5 Area Confluence Core
190 185 180 175 180 165
Mould one Mould two Mould three Mould four Mould five Side plate
192 191 190 191 192 195
Host speed: 20rpm host current; 75A
Feeding speed: 10rpm
Rolling gap: 4mm
Roller temperature: 175℃
Roller and traction speed: 600 (table value)
5. Stereotypes and others
Since the products in the production process have not been completely finalized, the cutting flow avoids stress, and the loaded tray needs to be firm and flat. Product testing also requires that the substrate and finished product be held for a certain period of time for sampling.
Analysis of common problems-poor product molding
1. The product size is unstable, the mold is not full, and the wall thickness is uneven
Reasons: Unreasonable internal and external lubrication of the formula, unstable quantitative feeding speed, severe wear of the screw barrel, and incorrect fit clearance;
Solution: Improve the ratio of internal and external slip agent, correct feeding failure, replace the barrel and screw, and adjust the gap between barrel and screw.
2. The appearance of the product is uneven, the color deviation is obvious, and irregular fish scales appear on the surface; the product performance is poor; the toughness is poor, the product is brittle, and the impact resistance is not qualified;
Reason: The formula structure is unreasonable, the inorganic filling is too high, the plasticization is poor, and the amount of impact material is insufficient;
Solution: Modify the formula structure, appropriately reduce the content of inorganic fillers, correct the plasticization of the material to about 65%, and increase the impact resistance material as appropriate.
3. The output of the finished product is curved, deformed, and partially subsidence;
Cause: The machine head and the shaping die are not on the same plane, the extrusion speed is too fast, the temperature of the cold water is too high, the water pressure is too small, the water flow is insufficient, the water and gas path is not smooth, and the vacuum negative pressure is insufficient;
Solution: Straighten the head die and the shaping die at the same level, reduce the extrusion speed & cooling water temperature, increase the water pressure and flow, adjust the vacuum negative pressure to check that the water and gas channels are smooth.
in conclusion
Only by fully understanding the product quality and processing requirements, combining equipment and materials, rationally designing the formulation and processing technology, and mastering its role and the relationship and influence between each other, can we balance product quality, production efficiency, formulation cost, and processing cost. Elements.
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