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Plasticizing process


Plasticizing is a process in which a polymer is mixed with a solid object and softened by heat into a viscous fluid state. This process allows the polymer to have better processing properties, so it is widely used in the manufacture of various plastic products.


Among them, the practical equipment for PVC plasticizing is a double-roll plasticizing machine. It cuts the material through rollers of different speeds, so as to achieve the effect of plasticizing. At the same time, the length of plasticizing time is also an important factor affecting the plasticizing effect. Select different plasticizing time according to different materials to ensure the best results.

Plasticizing can not only improve the processing properties of polymers, but also optimize their mechanical and physical properties. Therefore, plasticizing technology has become one of the important processes for the manufacture of various plastic products.

With the continuous development of science and technology, plasticizing technology is also constantly innovating. For example, on the basis of the traditional two-roll plasticizer, new plasticizers have emerged, such as single-screw plasticizer and twin-screw plasticizer. These new technologies can not only improve the efficiency of plasticizing, but also shorten the plasticizing time and reduce production costs.

Preparation of plasticizing process
Preparation for feeding
The polymer is sieved and magnetized before being added to the cylinder. The purpose of sieving is to remove some impurities, ensure the purity of the material and try to be uniform in the particle size of the material. Magnetic absorption treatment is to prevent the mixing of metallic substances. Other additives also need to undergo some treatment before use, such as preheating the plasticizer before mixing, and using some additives that are harmless to the human body and the environment. The feeding amount of a time should be controlled properly, and the feeding amount is different for different two-roll plastic refining machines.

Control of plasticizing temperature
Plasticizing temperature is mainly set according to the decomposition temperature of the material, the material is added from the roller, the higher the temperature of the roller, the material will melt, that is, the contact area of the material and the roller is large, the greater the adhesion, the material is easy to mix evenly, but the temperature of the roller cannot be too high, if the temperature is too high, the material may decompose. The temperature is too low, the contact is small, the adhesion is small, and the mixing is uneven, which is not conducive to plasticization.

Control of plasticizing time
The effect of plasticizing is proportional to the plasticizing time, the longer the plasticizing time, that is, the more evenly the material is mixed, the better the plasticizing effect, but the longer the time is too long, it will lead to low production efficiency, short plasticizing time, and the uneven mixing of materials, the effect is not ideal. Select different plasticizing time according to different materials, and the appropriate plasticizing time is the guarantee of plasticizing effect.

Initial mixing of materials

The initial mixing is not a violent mixing, it is a mixing below the melting point temperature of the polymer and under a small shear force. The purpose of the initial mixing is to perform a mixing before mixing in the later mixer to improve the mixing uniformity of the final product. The mixing process is to increase the degree of random arrangement of the components, which is a simple mixing.

Plasticizing of the initial mix

The initial mixture is plasticized, and the purpose of plasticizing is to increase its plasticity, so that the components are evenly mixed. Different plastics have their own suitable plasticizing conditions, the main control conditions are: plasticizing temperature, plasticizing time and shear stress. The end point of plasticizing can be determined by the degree of mixing uniformity and dispersion of the material, and can also be determined by measuring the tear strength of the plastic sample.

In short, plasticizing technology is an integral part of modern industrial development. It can improve the quality and production efficiency of plastic products, but also promote the development of environmental protection industry. We should actively explore and innovate plasticizing technology to contribute to sustainable development in the future.

 

For more information:

David +8613632376303WhatsApp/Wechat)

Email:[email protected]

https://www.potop-polymer.com/rubber-molding-line/silicone-forming-test-line.html

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Calendering Process and Conditions


  At present, the rolling molding are mainly PVC products, mainly soft PVC film and hard PVC sheet two kinds. Here, the production of PVC film is taken as an example to describe a complete rolling molding process. The rolling molding process of PVC film is based on PVC resin as the main raw material, according to the different requirements of the use of the film product, the other auxiliary materials (plasticizer, stabilizer, filler and other auxiliary materials) according to the different proportion of the formula, by measurement and mixing, added to the PVC resin. It is mixed evenly by the high-speed mixer, mixed and pre-plasticized by the mixer, extruder or open mixer, and then transported to the calender for calendering and forming. The production process is then shaped by cooling rollers.

1.Selection of ingredients for formulation

  Product formulation design should pay attention to the following points: Before formulation design, we should understand the application conditions of products, and distinguish the main and secondary items in the product quality requirements. The raw materials to be selected should pay attention to the interaction between the raw materials and the feasibility of the process operation. Pay attention to whether the materials used in the formula are harsh on the process operating conditions, and those raw materials that are sensitive to process temperature changes, not easy to mix with other raw materials, and easy to decompose should be used as little or as little as possible. The design of the formula to go through several repeated tests, the application of practice assessment, modify and perfect to determine a more ideal formula.

2.Mix and plasticize

  The main purpose of mixing and plasticizing is to ensure uniform dispersion and plasticization of the material. If the dispersion is not uniform, the plasticizing effect of each part of the resin will be different, resulting in defects such as fisheye, cold scar, and reduced flexibility of the film. If the plasticization is uneven, the film will produce defects such as markings and poor transparency. The dosing mixing system should not only be prepared into dry mixture according to the formula, but also feed in a certain order according to the properties of each raw material. Initial mixing can be selected kneading machine, high-speed mixer, etc., if necessary, heating or cooling water in the jacket for cooling. The temperature in the plasticizing process should not be too high or too low. The temperature is too high, the time is too long, the plasticizer will be lost, and the resin will be degraded. If the temperature is too low, there will be non-stick rolls and non-uniform plasticization phenomena, which will also reduce the mechanical properties of the film. Generally soft PVC film plasticizing suitable temperature between 165~170℃. In recent years, with the continuous progress of the production technology of the mixer extruder, the continuous calender feed is replacing the intermittent feed operation.

3.Colling

  The plasticized material is transported by belt, detected by metal detector, and fed to calender roll. Roll temperature, roll speed, speed ratio, storage capacity and roll distance are the key factors affecting the quality of rolled products, which are interrelated and restricted.

4.Roll temperature

  Sufficient heat in the roller is necessary to melt and plasticize and extend the material. The heat required in the process of material rolling comes from internal heat and external heat. Internal heat refers to the large amount of friction heat generated by the shear action when the roll rotates during the calendering process. External heat refers to the heating of the surface of the roll through the medium or electricity to make the roll have a certain temperature. The heat required by the material is certain, and the internal and external heat should be balanced, so the control of roll speed and roll temperature should be related to each other. The roller temperature control is mainly determined according to the factors of resin and additives in the formula. For example, the melting temperature of resin in the formula is low, the melting viscosity is low, and the plasticizer content is high. The internal heat is mainly affected by the roller speed. The faster the roll speed, the higher the shear friction heat, the greater the internal heat, so the external heat required is relatively small, so the roll temperature can be appropriately reduced. However, the simple increase of roll speed will inevitably shorten the rolling time and increase the roller separation force, which will make the product thicker, the storage amount and the transverse thickness distribution of the product change. If the roller speed is reduced, the calendering time is extended, and the separation force is reduced, the product will first become thin, and after heat, due to the reduction of friction heat, the surface will appear rough, opaque and even holes and other defects. When calendering, in order to enable the material to fit the roll in turn, to avoid clamping air and making the film without bubbles, the temperature of each roll is generally increased in turn, and the temperature difference of each roll is within the range of 5~10℃. In addition, the surface temperature of the calender roll should also be as consistent as possible, so that the horizontal thickness of the product can be uniform.

5.Roll speed and speed ratio

  Roll speed is the key factor that determines the production speed of calender. The roller speed is fast, the production efficiency is high, and the shrinkage rate of the product is also large. The roller speed should be determined by the flow characteristics of the rolled material and the thickness of the product. The ratio of the linear speed of two rollers adjacent to the calender is called the speed ratio of the roller. Adjust the speed of the calendering roller, so that each roller has a certain speed ratio, the main reason is to make the calendering material stick to the roller in turn, and the second is to improve the plasticization degree of the material. The roller speed ratio control of the calender should be moderate. When the speed ratio is too large, rolling phenomenon occurs, the thickness of the film will be uneven, and sometimes excessive internal stress will be generated. If the speed ratio is too small, the film will not suck the roll, resulting in air bubbles clamping in, affecting the quality of the product.

 

6.Storage between roll spacing and roll gap

  Roll distance is the minimum distance between two adjacent roll surfaces. The adjustment of roller spacing during calendering is not only to adapt to the requirements of different thickness products, but also to change the storage amount between each roll gap. The amount of material stored between roll gaps also has great influence on product quality. The amount of material stored between rollers is too much, the material stays too long before calendering, the temperature is reduced, and the surface of the film will be rough and there are bubbles inside when it enters the roll calendering. When the amount of storage is too small and the calendering material is in short supply, the surface of the film will wrinkle due to insufficient extrusion pressure.

7.Rolling effect

  Due to the tensile stress caused by large shear stress and velocity ratio on the longitudinal side of the calendered material on the calendering machine, the calendered material also produces molecular orientation along its longitudinal side, so that the film appears anisotropy in physical properties, which is called the calendering effect or orientation effect in the calendering molding. The size of the calender effect is affected by the calender temperature, roll speed to speed ratio, roll gap storage, product thickness and material properties. The calender effect makes the calender product anisotropic. The tensile strength and elongation at break are increased parallel to the calendering direction, but decreased perpendicular to the calendering direction. When the film is heated in the free state, the film shrinks in the longitudinal direction and expands in the transverse direction. Therefore, the thinner the rolled product, the more difficult it is to guarantee its quality. This is also why the film thickness is less than 0.05mm is rarely produced by calendering, and is produced by extrusion blown film.

8.Leading away, cooling, winding

  The calendered film removed from the third and fourth rollers of the four-roll calender passes through the removal roll, the ginning roll, the cooling roll and the winding roll to become the product. The speed of the leading roller is usually 25% to 35% faster than the speed of the main roller of the calender, in addition, in order to avoid the cold stretching of the product during the leading, and to prevent the plasticizer and other volatile substances from condensing on the surface of the leading roller affecting the product quality, it is necessary to heat the leading roller. The cooling setting device uses a series of cooling rollers, generally 4 to 8. The purpose of cooling is to reduce the temperature of the product for subsequent take-up. The coiling speed should be strictly controlled during the coiling process, so that it is always suitable for the rolling speed. In order to ensure the smooth progress of calendering, the generally controlled roll speed is: take-up speed ≧ cooling speed > removal speed > third roll speed.

Potop's calender is your best choice for PVC film production. We use the most advanced processes and technologies to provide you with high quality and efficient production solutions. Our calenders are able to produce soft PVC films and hard PVC sheets according to your requirements to suit a variety of applications.

  Our calendering mechanism makes the pressing process of PVC film very complete. We use PVC resin and various auxiliary materials, mixed in different proportions, and added to the high-speed mixer to stir evenly. Then, it is mixed and pre-plasticized by the mixer, extruder or open mixer, and then transported to the calender for calendering. Finally, high quality PVC film is produced by cooling roller.

  We have a professional R & D team and high-quality after-sales service personnel, can provide you with first-class technical support and after-sales service. We focus on providing our customers with the best solutions to meet the demand for PVC film in different sectors.
By choosing a Potop calender, you can confidently produce high-quality PVC films to meet your needs in different areas. We look forward to working with you to create a better future together!


Large extruder


For more information:
David +8613632376303(WhatsApp/Wechat)
Email:[email protected] 
http://www.potop-lab.com/
https://www.potop-polymer.com/mdo-stretcher/high-temperature-drawing-machine-for-polymer.html
https://www.potop-polymer.com/biaxial-stretcher/pp-bi-birectional-film-stretching-test-line.html

 What is calendering

  Calendering is a processing method for thin sheet products with width and thickness by means of strong shear force between rollers and corresponding processing temperature, so that the viscous fluid material is repeatedly extruded and extended. Plastic and rubber are calendering process, plastic with polyvinyl chloride resin as the main raw material.
  Principle: In the rolling molding process, with the help of the shear force produced between the rollers, the material is repeatedly squeezed and cut to increase the plasticity, and it is extended into a thin product on the basis of further plasticization. The extrusion and shearing action of the roller on the plastic changes the macro-structure and molecular form of the material, and plasticizes and extends the plastic under the temperature coordination. The result of the roller is a thinning of the material layer, and the extension increases the width and length of the material layer. In the process of calendering, when the roller squeezes and cuts the material, the roller is also subjected to the reaction force from the material, which is called the separation force that tries to separate the two rollers. Usually the roller can be designed and processed into a slightly waist drum shape, or adjust the axis of the two rollers, so that it crosses a certain Angle (axis cross) or prestress, you can overcome or reduce the harmful effect of the separation force to a certain extent, and improve the uniformity of the thickness of the rolled product. In the calendering process, due to the great shear stress of the thermoplastic, the macromolecules will have a directional effect along the direction of the film, so that the generated film in the physical and mechanical properties of anisotropy, this phenomenon is called the calendering effect. The size of the calendering effect is affected by the calendering temperature, rotational speed, feed thickness and physical properties, etc. The calendering effect can be reduced by heating up or increasing the calendering time.
  POTOP is an expert in the production of laboratory calender equipment, we have desktop three-roll calender, small precision three-layer coextrusion calender testing machine, small multi-layer calender production line, single screw extrusion calender test line and other different models. High strength European standard integrated frame, practical and beautiful; Each power roller is driven by servo motor independently, the roller speed control is accurate, and the synchronization performance is good. Hard chrome plated mirror roller with 304 stainless steel core, high surface finish, no rust; Brand PLC touch screen, easy to control, intelligent; Optional waste edge collection device, convenient waste recycling; Constant tension winding device can be selected to improve the film winding quality; The pattern roller/fog roller can be used to achieve different film surface treatment; Humanized structure design, more convenient operation. We are the preferred brand for laboratory testing and large-scale calender processing equipment. We also provide user-friendly after-sales service to protect customers' products.

For more information:
David +8613632376303
Email:[email protected] /[email protected]
http://www.potop-lab.com/

 

1.Polyethylene terephthalatePETPETEPET
Uses: polyester fiber, thermoplastic resin, tape and plastic bottles, commercial beverage bottles, edible oil bottles and other plastic bottles. Refer to the bottle recycling technology, heat 60-85 °C (140-185 °F) and acid and alkali resistance, overheating and long-term use may release the plasticizer dioctyl phthalate (DEHP) [10]. However, in general, PET materials do not add plasticizers.
White or transparent (rapid cooling during processing).
Plastic distinguishing features: The bottle body is formed without seams, and there will be a dot at the bottom. Easy to burn, burning will have black smoke and aromatic sweet, melt down after burning.

2.PEHigh-density polyethyleneHDPEPEHD
Uses: bottles, shopping bags, recycling buckets, agricultural pipes, cup holders, car barriers, fresh milk bottles, alcohol bottles, sports equipment and composite plastic wood, heat resistance 90-110 °C (194-230 °F) corrosion resistance, acid and alkali resistance, not easy to thoroughly clean residue, food containers should not be reused after cleaning.
It is white and translucent.
Plastic distinguishing features: feel like wax, bottle products are mostly opaque, plastic bag products rub or rub when rustling. Easy to burn, there is no black smoke and candle smell when burning, the flame tip is yellow and the lower end is green, and it is not extinguished when it is removed from the fire source.

3.PVCPolyvinyl chloridePVC/ V
Application: pipe, wall and non-food bottle, plastic wrap, egg carton, seasoning jar, etc.
Heat resistance 60-80 °C (140-176 °F), overheating easily releases a variety of toxic additives (used to improve the performance of this type of plastic, plasticizers containing environmental hormones) Generally PVC will have a large number of plasticizers in the process. Plasticizers are now available in non-toxic formulations, so PVC can continue to be widely used in a variety of products.
It is colorless and transparent.
The bottom of the round bottle product is a straight line, white marks will appear when it is folded vigorously, and it will become iron red after long-term exposure in the sun; Poor ductility will be extinguished naturally when it leaves the fire source, and there will be a blue flame on the edge of combustion, with black smoke and scorched taste of hydrochloric acid.

4.PELow-density polyethylene(LDPE/PELD)
Uses: plastic bags, various containers, medicine bottles, washing bottles, piping and all kinds of molded laboratory equipment.
Heat resistance 70-90 °C (158-194 °F), corrosion resistance, acid and alkali resistance, overheating easy to produce carcinogens.
White translucent/Thin film products appear transparent.
Plastic bag products are softer and less rustling when kneading; The packaging film is easier to tear. Easy to burn, there is no black smoke and candle smell when burning, the flame tip is yellow and the lower end is green, and it is not extinguished when it is removed from the fire source.

5.PPPolypropylene
Uses: auto parts, industrial fiber and food containers, food utensils, water cups, pudding boxes, soy milk bottles, alcohol bottles, physiological salt liquid bottles, etc.
Heat to 100-140 °C (212-284 °F), acid and alkali resistance, chemical resistance, collision resistance, high temperature resistance, in the general food handling temperature is safer.
It is white and translucent.
The hardness is high and the surface is shiny. Easy to burn, no black smoke and diesel candle smell when burning, yellow or blue flame, not extinguished when removed from the fire source, burn quickly and completely after burning.



6.PSPolystyrene
Uses: desk accessories, self-help trays, food utensils, toys, video cassette, Yro Do bottles, ice cream containers, foam bowls, spacers and Expanded polystyrene (EPS) products, such as styrene.
Heat resistance 70-90 °C (158-194 °F), low water absorption, good stability, acid and alkali solution (such as orange juice, etc.) or high temperature is easy to release carcinogens, not applicable to alcohol, not applicable to edible oils.
It is colorless and transparent.
It can be torn by hand, and white marks appear when it is broken lightly, and there is diffusion. Easy to burn, burning will have the smell of styrene, orange yellow black smoke, removed from the fire source is not extinguished, softened after burning.



7.OTHER/O include: melamine, ABS resin (ABS), polymethyl methacrylate (PMMA, one of the acrylic), polycarbonate (PC), polylactic acid (PLA), nylon and glass fiber reinforced plastics.
Use: food utensils.

· Polycarbonate (PC) heat resistant 120-130 °C (248-266 °F), not suitable for alkali;

· Polylactic acid (PLA) heat resistant to 50 °C (122 °F);

· Acrylic (PMMA) heat resistance 70-90 °C (158-194 °F), not suitable for alcohol;

· The heat resistance of the resin is 110-130 °C (230-266 °F), but there may be doubts about the dissolution of phenol methane (bisphenol A), so it is not recommended to hold hot food

· Polycarbonate (PC) heat resistant 120-130 °C (248-266 °F), not suitable for alkali;

· Polylactic acid (PLA) heat resistant to 50 °C (122 °F);

· Acrylic (PMMA) heat resistance 70-90 °C (158-194 °F), not suitable for alcohol;

· The heat resistance of the resin is 110-130 °C (230-266 °F), but there may be doubts about the dissolution of phenol methane (bisphenol A), so it is not recommended to hold hot food.



8. ABS
Used in food utensils.
Heat resistance 70-100 °C (158-212 °F), not suitable for alcohol.
It's beige.
  Plastic products are dazzling, the most diverse colors. To attract users to buy, and the testing of plastic properties, we are experts in related instruments. We have a complete set of experimental and trial production equipment for lithium electric separator using the process of thermal induced phase separation (TIPS), and have realized the mixing and extrusion, casting molding, bidirectional drawing, extraction molding, two-stage drawing and automatic winding of polymer materials. Such as lithium diaphragm production and preparation of the entire process of professional equipment. There are also small masterbatch dispersion tester, and filter pressure value tester, etc., suitable for various related plastic raw materials experiment and processing test.

For more information:

David +8613632376303

Email:[email protected] /[email protected]

http://www.potop-lab.com/

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