PVC pipe extrusion moulding process capable of effectively increasing impact strength

[0046] Example 1: A PVC pipe extrusion molding process that can effectively improve impact strength. The pipe formulation includes PVC resin, impact modifier, stabilizer, processing modifier, filler, pigment and external lubricant, specifically including Prepared in the following steps: various materials-weighing-kneading-extrusion granulation-extrusion molding-cooling molding-cutting-inspection-finished product;

[0047] 2) Mixing process

[0048] During high-speed mixing, the auxiliary agent penetrates into the voids of the PVC resin to make the auxiliary agent uniformly dispersed in the resin. Considering that the temperature above 1000°C is beneficial to the steaming of the material, the temperature of the hot mixer is set at 100-1200°C ; In order to allow the additives to fully contact with the PVC particles and reduce the adsorption of the filler to the additives, the hot mixer should be started after adding the PVC resin,

[0049] Add stabilizer at a temperature of 100-300℃;

[0050] Add processing aids at a temperature of 400-800℃;

[0051] Add colorant at a temperature of 900-1000℃;

[0052] Add filler at a temperature of 1000-1200℃;

[0053] The cold mix is ​​controlled to discharge when the material temperature is 400℃;

[0054] The temperature of the mixture discharged by the hot mixer is very high, and it needs to be cooled immediately. If the heat is not timely, it will cause the decomposition of the material and the volatilization of the additives; the cold mixing is controlled at the material temperature of 400 ℃;

[0055] 2) The extruder screw is divided into 3 sections: feeding section (feeding section), melting section (compression section), metering section (homogenization section), these three sections corresponding to the material constitute 3 functional areas: solid conveying Zone, material plasticizing zone, melt conveying zone.

[0056] The temperature of the barrel in the solid conveying zone is controlled at 100~1400℃; if the feeding temperature is too low, the solid conveying zone will be extended, reducing the length of the plasticizing zone and the melt conveying zone, which will cause poor plasticization and affect product quality;

[0057] The temperature of the material plasticization zone is controlled at 170~1900℃; controlling the vacuum degree of this section is an important process index. If the vacuum degree is low, it will affect the exhaust effect, resulting in bubbles in the pipe, which seriously reduces the pipe Mechanical properties, in order to make the gas inside the material easily escape, the plasticization degree of the material in this section should be controlled not to be too high, and the exhaust pipe should be cleaned frequently to avoid blockage; the vacuum degree of the barrel is generally 0.08~0.09MPa;

[0058] The temperature of the melt conveying zone should be slightly lower, 160~1800℃; in this section, increasing the screw speed, reducing the head resistance and increasing the pressure in the plasticizing zone are all conducive to the increase of the conveying rate. For heat-sensitive PVC Plastics should not stay too long in this period. The screw speed is generally 20-30r/min;

[0059] The die is an important part of extruded product molding, its function is to generate a higher melt pressure and make the melt into the required shape. The process parameters of each part are: die connector temperature 1650℃, die temperature 1700℃, 1700℃, 1650℃, 1800℃, 1900℃;

[0060] 3) Shaping process

[0061] The tube extruded from the die of the machine head needs to be cooled to make it hard and shaped. The outer diameter is shaped with a sizing sleeve. The length of the sizing sleeve for outer diameter setting is generally 3 times its inner diameter. Cooling of the pipe The method is vacuum cooling forming. Vacuum cooling forming is to evacuate the vacuum tank with the help of a vacuum pump, so that the outer wall of the tube blank is adsorbed on the inner wall of the shaping sleeve to achieve cooling and shaping. The process conditions for vacuum shaping are: vacuum degree 20.0-53.3kPa, The water temperature is 15~250℃, and the water in the vacuum tank becomes misty; if the vacuum degree is too small, the outer diameter of the tube is too small, which is smaller than the standard size; on the contrary, if the vacuum degree is too large, the tube diameter is too large, and even appears Swelling phenomenon. If the water temperature is too low, the shaping will be incomplete, and the brittleness of the pipe will increase; if the water temperature is too high, it will cause poor cooling and cause the pipe to be easily deformed;

[0062] 4) Traction process

[0063] The function of the traction device is to provide a certain traction and traction speed for the pipe extruded by the die, draw the pipe uniformly, and adjust the wall thickness of the pipe by adjusting the traction speed. The traction speed depends on the extrusion speed, and the traction speed is higher than the extrusion speed. 1% to 3% faster.

[0064] In order to obtain rapid and uniform plasticization, the suspension method should be used for loose resin;

[0065] ——The resin used for double-wall corrugated pipes should especially have good molecular weight distribution and impurities to reduce the "fish eyes" in the pipe and avoid the collapse of the pipe corrugation and the rupture of the pipe wall;

[0066] ——The resin used in the water supply pipe should be of "sanitary grade", and the residual vinyl chloride in the resin should be within 1 mg/kg;

[0067] In order to ensure the quality of pipes and reduce the rate of defective products, the source of resin should be stable.

[0068] The stabilizers are: three basic lead sulfate and two basic lead salts, metal soaps, composite lead salt stabilizers, rare earth composite stabilizers, organotin stabilizers, heavy metal-containing stabilizers (such as Pb, Ba, Cd) It is harmful to human health, and the amount of these stabilizers in the water supply pipe formulation is limited; the single-screw extrusion process has a longer history of material heating than the twin-screw extrusion process, and the amount of stabilizer is 25% more than the latter; The temperature of the head of the wall bellows is higher, and the material stays in the head for a long time. The amount of stabilizer in the formula is 10% more than that of the ordinary pipe formula.

[0069] The function of the filler is to reduce the cost; the use of ultra-fine active filler, the amount of pipe material is larger than that of the profile, and the excessive amount of filler will reduce the impact resistance and the pressure resistance of the pipe. Therefore, in the chemical pipe and water supply pipe, the amount of filler Within 10 parts; the amount of filler in the drain pipe and cold-formed threading sleeve can be more, and the amount of CPE can be increased to change the impact performance;

[0070] For pipes with lower pipe performance requirements, and rain pipes, the amount of filler can be large, but the twin-screw extruder wears more seriously.

[0071] The matching design of external lubricant and stabilizer; organic tin stabilizer, organic tin stabilizer has good compatibility with PVC resin, and has a serious tendency to adhere to metal walls. It is the cheapest external lubricant to match Paraffin wax-calcium stearate system based on paraffin wax;

[0072] Lead salt stabilizer, lead salt stabilizer has poor compatibility with PVC resin, only attached to the surface of PVC particles, hindering the fusion between PVC particles, usually lead stearate-calcium stearate external lubricant is used to match it.

[0073] When using an impact-resistant toughening modifier, due to the high melt viscosity, the possibility of adhesion to the metal surface is high, and the amount of external lubricant is often needed; the thin-walled tube extruded with the same equipment is better than the same specification The thick-walled pipe requires more external lubricant. When the processing temperature is high, the melt tends to adhere to the metal surface, and more external lubricant is added.

[0074] The copolymer of PVC resin and neoprene includes the following components:

[0075]

[0076] The preparation method of the copolymer of PVC resin and neoprene includes:

[0077] Step 1: Put water and disodium hydrogen phosphate into a stirring tank according to the ratio, and heat to 60°C under constant stirring, so that the disodium hydrogen phosphate solution is completely dissolved, and the corn starch and disodium hydrogen phosphate solution are mixed thoroughly according to the ratio Add to the reactor, the material is stirred in the reactor and the temperature is increased to 70-80°C. When the water content is reduced to less than 20%, the temperature is increased to 150-200°C to make the starch and disodium hydrogen phosphate react. When the viscosity of the material is greater than 50Pa· At s, the reaction is terminated, the temperature is lowered and the material is discharged to obtain phosphate starch;

[0078] Step 2: Mix 50% sodium hydroxide aqueous solution, lime water and PVC resin;

[0079] Step 3: Add the mixed solvent in step 2 and the phosphate starch in step 1 into the bottle and stir for 5-9 hours;

[0080] Step 4: Add paraffin wax and stabilizer to the reaction kettle, stir at 90°C for 4 hours to completely dissolve the paraffin wax, and cool to 75°C;

[0081] Mix glycerin and novolac, add the mixture of step 3 and step 4, drip in about 1-2 hours, keep the reaction for 1 hour, then add neoprene, continue heating and stirring for 1 hour, and the temperature drops below 50°C.

[0082] There is no fixed melting point. It starts to soften at 80~85℃, becomes viscoelastic at 130℃, and becomes viscous at 160~180℃; it has good mechanical properties, tensile strength is about 60MPa, impact strength is 5~10kJ/m2 ; Has excellent dielectric properties.

[0083] Example 2: A PVC pipe extrusion molding process that effectively improves impact strength. The pipe formulation includes PVC resin, impact modifier, stabilizer, processing modifier, filler, colorant and external lubricant, specifically including Prepared by the following steps: various materials-weighing-kneading-extrusion granulation-extrusion molding-cooling molding-cutting-inspection-finished product;

[0084] 3) Mixing process

[0085] During high-speed mixing, the auxiliary agent penetrates into the voids of the PVC resin to make the auxiliary agent uniformly dispersed in the resin. Considering that the temperature above 1000°C is beneficial to the steaming of the material, the temperature of the hot mixer is set at 100-1200°C ; In order to allow the additives to fully contact with the PVC particles and reduce the adsorption of the filler to the additives, the hot mixer should be started after the PVC resin is added;

[0086] Add stabilizer at a temperature of 100-300℃;

[0087] Add processing aids at a temperature of 400-800℃;

[0088] Add colorant at a temperature of 900-1000℃;

[0089] Add filler at a temperature of 1000-1200℃;

[0090] The cold mix is ​​controlled to discharge when the material temperature is 400℃;

[0091] The temperature of the mixture discharged by the hot mixer is very high, and it needs to be cooled immediately. If the heat is not timely, it will cause the decomposition of the material and the volatilization of the additives; the cold mixing is controlled at the material temperature of 400 ℃;

[0092] 2) The extruder screw is divided into 3 sections: feeding section (feeding section), melting section (compression section), metering section (homogenization section), these three sections corresponding to the material constitute 3 functional areas: solid conveying Zone, material plasticizing zone, melt conveying zone.

[0093] The temperature of the barrel in the solid conveying zone is controlled at 100~1400℃; if the feeding temperature is too low, the solid conveying zone will be extended, reducing the length of the plasticizing zone and the melt conveying zone, which will cause poor plasticization and affect product quality;

[0094] The temperature of the material plasticization zone is controlled at 170~1900℃; controlling the vacuum degree of this section is an important process index. If the vacuum degree is low, it will affect the exhaust effect, resulting in bubbles in the pipe, which seriously reduces the pipe Mechanical properties, in order to make the gas inside the material easily escape, the plasticization degree of the material in this section should be controlled not to be too high, and the exhaust pipe should be cleaned frequently to avoid blockage; the vacuum degree of the barrel is generally 0.08~0.09MPa;

[0095] The temperature of the melt conveying zone should be slightly lower, 160~1800℃; in this section, increasing the screw speed, reducing the head resistance and increasing the pressure in the plasticizing zone are all conducive to the increase of the conveying rate. For heat-sensitive PVC Plastics should not stay too long in this period. The screw speed is generally 20-30r/min;

[0096] The die is an important part of extruded product molding, its function is to generate a higher melt pressure and make the melt into the required shape. The process parameters of each part are: die connector temperature 1650℃, die temperature 1700℃, 1700℃, 1650℃, 1800℃, 1900℃;

[0097] 3) Shaping process

[0098] The tube extruded from the die of the machine head needs to be cooled to make it hard and shaped. The outer diameter is shaped with a sizing sleeve. The length of the sizing sleeve for outer diameter setting is generally 3 times its inner diameter. Cooling of the pipe The method is vacuum cooling forming. Vacuum cooling forming is to evacuate the vacuum tank with the help of a vacuum pump, so that the outer wall of the tube blank is adsorbed on the inner wall of the shaping sleeve to achieve cooling and shaping. The process conditions for vacuum shaping are: vacuum degree 20.0-53.3kPa, The water temperature is 15~250℃, and the water in the vacuum tank becomes misty; if the vacuum degree is too small, the outer diameter of the tube is too small, which is smaller than the standard size; on the contrary, if the vacuum degree is too large, the tube diameter is too large, and even appears Swelling phenomenon. If the water temperature is too low, the shaping will be incomplete, and the brittleness of the pipe will increase; if the water temperature is too high, it will cause poor cooling and cause the pipe to be easily deformed;

[0099] 4) Traction process

[0100] The function of the traction device is to provide a certain traction and traction speed for the pipe extruded by the die, draw the pipe uniformly, and adjust the wall thickness of the pipe by adjusting the traction speed. The traction speed depends on the extrusion speed, and the traction speed is higher than the extrusion speed. 1% to 3% faster.

[0101] In order to obtain rapid and uniform plasticization, the suspension method should be used for loose resin;

[0102] ——The resin used for double-wall corrugated pipes should especially have good molecular weight distribution and impurities to reduce the "fish eyes" in the pipe and avoid the collapse of the pipe corrugation and the rupture of the pipe wall;

[0103] ——The resin used in the water supply pipe should be of "sanitary grade", and the residual vinyl chloride in the resin should be within 1 mg/kg;

[0104] In order to ensure the quality of pipes and reduce the rate of defective products, the source of resin should be stable.

[0105] The stabilizers are: three basic lead sulfate and two basic lead salts, metal soaps, composite lead salt stabilizers, rare earth composite stabilizers, organotin stabilizers, heavy metal-containing stabilizers (such as Pb, Ba, Cd) It is harmful to human health, and the amount of these stabilizers in the water supply pipe formulation is limited; the single-screw extrusion process has a longer history of material heating than the twin-screw extrusion process, and the amount of stabilizer is 25% more than the latter; The temperature of the head of the wall bellows is higher, and the material stays in the head for a long time. The amount of stabilizer in the formula is 10% more than that of the ordinary pipe formula.

[0106] The function of the filler is to reduce the cost; the use of ultra-fine active filler, the amount of pipe material is larger than that of the profile, and the excessive amount of filler will reduce the impact resistance and the pressure resistance of the pipe. Therefore, in the chemical pipe and water supply pipe, the amount of filler Within 10 parts; the amount of filler in the drain pipe and cold-formed threading sleeve can be more, and the amount of CPE can be increased to change the impact performance;

[0107] For pipes with lower pipe performance requirements, and rain pipes, the amount of filler can be large, but the twin-screw extruder wears more seriously.

[0108] The matching design of external lubricant and stabilizer; organic tin stabilizer, organic tin stabilizer has good compatibility with PVC resin, and has a serious tendency to adhere to metal walls. It is the cheapest external lubricant to match Paraffin wax-calcium stearate system based on paraffin wax;

[0109] Lead salt stabilizer, lead salt stabilizer has poor compatibility with PVC resin, only attached to the surface of PVC particles, hindering the fusion between PVC particles, usually lead stearate-calcium stearate external lubricant is used to match it.

[0110] When using an impact-resistant toughening modifier, due to the high melt viscosity, the possibility of adhesion to the metal surface is high, and the amount of external lubricant is often needed; the thin-walled tube extruded with the same equipment is better than the same specification The thick-walled pipe requires more external lubricant. When the processing temperature is high, the melt tends to adhere to the metal surface, and more external lubricant is added.

[0111] The copolymer of PVC resin and neoprene includes the following components:

[0112]

[0113]

[0114] The preparation method of the copolymer of PVC resin and neoprene includes:

[0115] Step 1: Put water and disodium hydrogen phosphate into a stirring tank according to the ratio, and heat to 60°C under constant stirring, so that the disodium hydrogen phosphate solution is completely dissolved, and the corn starch and disodium hydrogen phosphate solution are mixed thoroughly according to the ratio Add to the reactor, the material is stirred in the reactor and the temperature is increased to 70-80°C. When the water content is reduced to less than 20%, the temperature is increased to 150-200°C to make the starch and disodium hydrogen phosphate react. When the viscosity of the material is greater than 50Pa· At s, the reaction is terminated, the temperature is lowered and the material is discharged to obtain phosphate starch;

[0116] Step 2: Mix 50% sodium hydroxide aqueous solution, lime water and PVC resin;

[0117] Step 3: Add the mixed solvent in step 2 and the phosphate starch in step 1 into the bottle and stir for 5-9 hours;

[0118] Step 4: Add paraffin wax and stabilizer to the reaction kettle, stir at 90°C for 4 hours to completely dissolve the paraffin wax, and cool to 75°C;

[0119] Mix glycerin and novolac, add the mixture of step 3 and step 4, drip in about 1-2 hours, keep the reaction for 1 hour, then add neoprene, continue heating and stirring for 1 hour, and the temperature drops below 50°C.

[0120] There is no fixed melting point. It starts to soften at 80~85℃, becomes viscoelastic at 130℃, and becomes viscous at 160~180℃; it has good mechanical properties, tensile strength is about 60MPa, impact strength is 5~10kJ/m2 ; Has excellent dielectric properties.