Method for increasing production speed of extrusion casting machine equipped with rubber roller and application thereof

Abstract

The invention discloses a method for increasing the production speed of an extrusion casting machine provided with a rubber roller and application of the method, the method for increasing the production speed of the extrusion casting machine provided with the rubber roller comprises the operation of uniformly coating water on the surface of the rubber roller to form a water coating layer, and the water coating layer is formed by forming a water film between the rubber roller and a plastic film. The service life of the rubber roller can be obviously prolonged, and meanwhile the production speed of the extrusion casting machine is increased.

Description

Technical Field

[0001] The invention relates to the field of plastic film preparation, in particular to a method for improving the production speed of an extrusion casting machine equipped with a rubber roller and application thereof. Background Art

[0002] The cast extrusion film production process involves melting and plasticizing the resin in an extruder, squeezing it through a slot die, and depositing the melt onto a cooling roller. The film is then stretched, trimmed, and wound up. The key to producing thermoformed plastic film using the cast extrusion process is ensuring close contact between the film and the roller. Failure to do so can result in an uneven surface, reduced transparency, and poor secondary processing properties, impacting the quality of the final thermoformed plastic product. Therefore, equipment typically incorporates air knives, rubber rollers, and metal wheels to maintain close contact between the film and the roller.

[0003] Equipping the cooling roller of the extrusion cast film machine with an air knife will make the overall structure of the extrusion cast film machine more complicated, requiring more precision components and control systems to ensure the normal operation of the air knife, which will increase the manufacturing difficulty and cost of the equipment; and the air knife's parameters such as air pressure and air volume need to be precisely adjusted according to production conditions to ensure the quality and stability of the cast film, which requires the operator to have high professional skills and experience, increasing the difficulty of operation; and if a high-efficiency air knife system is used, although the compressed air consumption can be reduced, overall, the operation of the air knife still requires a certain amount of energy. If equipped with metal wheels, the steel wheel to steel wheel cooling method can provide efficient cooling effect, but it is a challenge to ensure uniform temperature of the entire steel wheel surface. Uneven temperature may cause internal stress in the extruded material during the cooling process, thereby affecting the dimensional accuracy and shape stability of the product; and the steel wheel to steel wheel cooling method is not suitable for the production of thin films with a thickness of less than 0.2mm and with textures; the steel wheel to steel wheel cooling method is not suitable for materials that are sensitive to temperature changes, and the materials may be prone to defects during the cooling process; rubber rollers have excellent elasticity due to their material properties, and can provide better adaptability when in contact with the film, ensuring uniform and stable pressure distribution, which helps to reduce deformation and damage of the film during the cooling and shaping process, improve product quality, and can simplify the process without causing energy waste. Therefore, equipping rubber rollers at the cooling rollers of the extrusion casting machine is a more appropriate choice.

[0004] However, there are certain defects in equipping rubber rollers. Due to the poor thermal conductivity of rubber rollers, the surface temperature of the rubber rollers is too high, and the molten material adheres to the surface of the rubber rollers, which reduces the production speed and reduces the overall efficiency of the production line. In addition, rubber materials are prone to aging, hardening or softening in high temperature environments. During the extrusion cast production process, the surface temperature of the rubber rollers is too high, which accelerates the aging process of the rubber, causing it to lose its original elasticity and wear resistance, resulting in a decline in the quality of the extrusion cast products.

[0005] Therefore, there is an urgent need to develop a method that can increase the production speed of an extrusion casting machine equipped with a rubber roller while ensuring the service life of the rubber roller and promoting the development of plastic film production technology. Summary of the Invention

[0006] In view of the defects in the prior art, the present invention proposes a method for increasing the production speed of an extrusion casting machine equipped with a rubber roller and its application.

[0007] The present invention provides a method for increasing the production speed of an extrusion casting machine equipped with a rubber roller, comprising the following steps:

[0008] S1: Mix, convey, measure, extrude and plasticize the raw materials according to the formula ratio to obtain the melt, and then convey it to the die head;

[0009] S2: Water is evenly applied to the surface of the rubber roller to form a water coating layer. The melt extruded from the die head flows between the rubber roller and the metal texture roller, and is pulled to the metal cooling roller for cooling and shaping. It then enters the thickness measurement, cooling or tempering, trimming, winding, slitting, inspection, and packaging processes to finally obtain the finished product;

[0010] Among them, a water column is formed above the contact between the rubber roller and the melt, and a water film is formed at the contact between the melt and the rubber roller;

[0011] The diameter of the water column is 0.5-3 mm.

[0012] Evenly applying water to the surface of the rubber roller can quickly reduce the surface temperature of the rubber roller, thereby preventing the molten material from adhering to the surface of the rubber roller when in contact with the rubber roller and affecting the production speed, while reducing the possibility of aging of the rubber material.

[0013] Because water evaporates very quickly at high temperatures, it can cause an uneven or absent water film when the rubber roller contacts the base film melt. Therefore, the diameter of the water column is controlled by adjusting the opening width (lip gap) of the slot die and the cavity pressure, depending on the production speed. The inventors have discovered that by controlling the water column diameter within this specific range, they can maintain a balance between the amount of water applied and water consumption at typical production speeds, ensuring a uniform water film adheres to the rubber roller surface. The presence of the water film lubricates and isolates the plastic film, making it easier to peel it from the rubber roller, further increasing production speed. Furthermore, the lubricating effect of the water film reduces wear on the rubber roller, extending its life.

[0014] Furthermore, the operation of uniformly coating water on the surface of the rubber roller to form a water coating layer is completed by a precision slot coating die, and the amount of water applied is controlled by controlling the die lip gap (gasket thickness) and the cavity pressure (pressure of the die water) of the precision slot coating die, wherein the die lip gap is maintained at 10-50 μm and the cavity pressure is maintained at 0.05-0.15 MPa to maintain the stability of the water film at the contact point between the rubber roller and the plastic film.

[0015] Furthermore, the diameter of the water column is 1-2 mm.

[0016] Furthermore, the surface tension of water is 32-58 mN / m, and the surface tension of water is measured by a pendant drop method.

[0017] Furthermore, 0.5wt%-2wt% of a surfactant is added to the water. The surface tension of water at 25°C is about 72mN / m. By adding a small amount of surfactant, the surface tension of water can be reduced to between 32-58mN / m, which can reduce production costs and at the same time reduce the impact of surfactants on subsequent processing and use.

[0018] Furthermore, the surfactant is any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate (SDBS), polyvinyl alcohol, hexadecanol polyoxyethylene ether, and ethanol.

[0019] Furthermore, the surface dyne value of the rubber roller is 35-60 mN / m. By limiting the surface dyne value, the water film layer can be more easily and evenly covered on the surface of the rubber roller, thereby better achieving the functions of reducing the surface temperature of the rubber roller and lubricating and isolating.

[0020] The present invention also provides application of the method in preparing plastic film, characterized in that the production speed of the method reaches above 40 m / min.

[0021] Furthermore, after adopting this method, the service life of the rubber roller reaches more than 1.1 million meters.

[0022] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0023] (1) The method provided by the present invention can significantly increase the production speed of the extrusion casting machine while making the plastic film adhere closely to the roller;

[0024] (2) The method provided by the present invention can also increase the service life of the rubber roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a schematic diagram of the high-speed casting process of the present invention.

[0027] Reference numerals:

[0028] 1-casting machine die head, 2-precision slot coating die head, 3-rubber roller, 4-metal textured roller, 5-metal cooling roller, 6-water receiving trough, 7-water column, 8-film. DETAILED DESCRIPTION

[0029] In order to help those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0030] Example

[0031] The present invention is further described below with reference to specific examples and comparative examples. The following specific examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and are particularly not limited to the types of the various component raw materials used in the following specific examples.

[0032] Note: 1. The surfactant added to the water in Examples 1-3 is 0.8 wt %, the surface tension of water is 38 mN / m, and the surface dyne values ​​of the rubber rollers in Examples 1-3 and Comparative Example 1 are 42, 50, 58, and 36 mN / m, respectively.

[0033] 2. The production speeds in Examples 1-3 and Comparative Example 1 were measured using a stopwatch, and the production life of the rubber roller was determined based on the following criteria: When the surface roughness Rz value changed from 4.5 to 26, the rubber roller could no longer meet the product quality requirements and needed to be replaced. The length of film produced from the time the rubber roller started working to the time it was replaced was used as the result.

[0034] Example 1

[0035] The production of 0.2mm PP film includes the following steps:

[0036] S1: Mix, convey, meter, extrude and plasticize the PP raw materials according to the formula ratio to obtain PP melt, and then convey it to the die head;

[0037] S2: Water is evenly applied to the surface of the rubber roller to form a water coating layer. The PP melt extruded from the die head flows between the rubber roller and the metal texture roller, and is pulled to the metal cooling roller for cooling and shaping. It then enters the thickness measurement, cooling, edge cutting, winding, slitting, inspection, and packaging processes to finally obtain the finished product;

[0038] Among them, the temperatures of the six zones of the screw are: zone 1 220℃, zone 2 230℃, zone 3 240℃, zone 4 240℃, zone 5 245℃, zone 6 250℃; die head temperature: 250℃; die lip gap: 400μm; texture roller speed 45.5m / min; cooling roller speed: 45.7m / min; winding speed: 46m / min; rubber roller cavity cooling control 6-8℃; rubber roller pressure: 4MPa; slit die lip gap 40μm; cavity pressure: 0.08MPa; water column diameter: 2-3mm.

[0039] The production speed of the 0.2 mm PP film of Example 1 reaches 46 m / min, and the service life of the rubber roller reaches 1.2 million meters.

[0040] Example 2

[0041] The production of 0.12mm PP film includes the following steps:

[0042] S1: Mix, convey, meter, extrude and plasticize the PP raw materials according to the formula ratio to obtain PP melt, and then convey it to the die head;

[0043] S2: Water is evenly applied to the surface of the rubber roller to form a water coating layer. The PP melt extruded from the die head flows between the rubber roller and the metal texture roller, and is pulled to the metal cooling roller for cooling and shaping. It then enters the thickness measurement, cooling, edge cutting, winding, slitting, inspection, and packaging processes to finally obtain the finished product;

[0044] Among them, the temperatures of the six zones of the screw are: zone 1 210℃, zone 2 220℃, zone 3 225℃, zone 4 230℃, zone 5 235℃, zone 6 240℃; die head temperature: 240℃; die lip gap: 300μm; texture roller speed 59.0m / min; cooling roller speed: 59.3m / min; winding speed: 60m / min; rubber roller cavity cooling control 6-8℃; rubber roller pressure: 3MPa; slit die lip gap 30μm, cavity pressure: 0.1MPa; water column diameter: 1-2mm.

[0045] The production speed of the 0.12 mm PP film of Example 2 reaches 60 m / min, and the service life of the rubber roller reaches 1.5 million meters.

[0046] Example 3

[0047] The production of 0.2mm PETG film includes the following steps:

[0048] S1: PETG raw materials are mixed, conveyed, metered, extruded and plasticized according to the formula ratio to obtain PETG melt, and then conveyed to the die head;

[0049] S2: Water is evenly applied to the surface of the rubber roller to form a water coating layer. The PETG melt extruded from the die head flows between the rubber roller and the metal texture roller, and is pulled to the metal cooling roller for cooling and shaping. It then enters the thickness measurement, tempering, trimming, winding, slitting, inspection, and packaging processes to finally obtain the finished product;

[0050] Among them, the temperatures of the six zones of the screw are: zone 1 235℃, zone 2 240℃, zone 3 245℃, zone 4 250℃, zone 5 255℃, zone 6 265℃; die head temperature: 260℃; die lip gap: 400μm; texture roller speed 51.2m / min; cooling roller speed: 51.5m / min; winding speed: 52m / min; rubber roller cavity cooling control 6-8℃; rubber roller pressure: 5MPa; slit die lip gap 50μm; cavity pressure: 0.12MPa; water column diameter: 2-3mm.

[0051] The production speed of the 0.2 mm PETG film of Example 3 reaches 52 m / min, and the service life of the rubber roller reaches 1.2 million meters.

[0052] Comparative Example 1

[0053] 0.2mm PP film is produced according to conventional processes, which does not include the operation of evenly coating water on the surface of the rubber roller to form a water coating layer. The temperatures of the six screw zones are: Zone 1 210°C, Zone 2 220°C, Zone 3 225°C, Zone 4 230°C, Zone 5 235°C, and Zone 6 240°C; the die head temperature is 240°C; the die lip gap is 400μm; the textured roller speed is 17.3m / min; the cooling roller speed is 17.5m / min; the winding speed is 18m / min; the cooling in the rubber roller cavity is controlled at 6-8°C; the rubber roller surface temperature reaches 48-50°C; and the rubber roller pressure is 8MPa.

[0054] Due to the poor heat dissipation performance of rubber rollers, the surface temperature of the rubber rollers rises rapidly as the production speed increases. When the production speed reaches 18m / min, the surface temperature of the rubber rollers reaches 48-50℃. The rubber rollers are exposed to high temperature, high pressure, and high viscosity for a long time, and the surface of the rubber rollers easily becomes rough, thereby reducing the service life of the rubber.

[0055] The production speed of the 0.2 mm PP film in Comparative Example 1 is 18 m / min, and the life of the rubber roller is 600,000 meters.

[0056] Comparative Example 2

[0057] The film production process differs from that of Example 1 in that: the slit die lip gap is 20 μm; the die cavity pressure is 0.05 MPa; and the water column diameter is 0.25-0.35 mm.

[0058] The production speed of the 0.2 mm PP film in Comparative Example 2 reached 35 m / min, and the service life of the rubber roller reached 880,000 meters.

[0059] Comparative Example 3

[0060] The film production process differs from that of Example 1 in that: the slit die lip gap is 45 μm; the die cavity pressure is 0.2 MPa; and the water column diameter is 3.5-4.5 mm.

[0061] The production speed of the 0.2 mm PP film in Comparative Example 3 reached 50 m / min, but due to the large diameter of the water column, it brought too much water onto the plastic film, causing the film to cool prematurely and the embossing effect to deteriorate, directly affecting product quality.

[0062] The production methods of Examples 1-3 all include the step of evenly coating the surface of a rubber roller with water to form a water coating layer. This separates the rubber roller from the plastic film through the water film, preventing the film from adhering to the rubber roller due to high temperatures and slowing production. The lubricating effect of the water film also extends the service life of the rubber roller. The extrusion casting machines equipped with the rubber rollers in Examples 1-3 all achieved production speeds of 46 m / min or higher, and the rubber rollers all achieved a service life of 1.1 million meters or higher.

[0063] In Comparative Example 1, the PP film production process failed to uniformly apply water to the rubber roller surface to form a water coating, significantly reducing production speed and the service life of the rubber roller. In Comparative Example 2, the water column diameter was too small, making it impossible to balance the amount of water applied with water consumption, resulting in a significant decrease in production speed and a reduction in the service life of the rubber roller. In Comparative Example 3, the water column diameter was too large, directly affecting the embossing effect of the product. Therefore, the above comparative examples failed to simultaneously increase production speed and ensure close adhesion between the film and the roller, nor could they guarantee the long-term use of the rubber roller. This shows that the production method of the present invention offers significant advantages over the comparative examples and can effectively meet the high standards of customers and the market.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for increasing the production speed of an extrusion casting machine equipped with a rubber roller, characterized in that: The steps include: S1: Mix, convey, measure, extrude and plasticize the raw materials according to the formula ratio to obtain the melt, and then convey it to the die head; S2: Water is evenly coated on the surface of the rubber roller to form a water coating layer. The melt extruded from the die head flows between the rubber roller and the metal texture roller, and is pulled to the metal cooling roller for cooling and shaping. Then, the process of thickness measurement, cooling or tempering, trimming, winding, slitting, inspection, and packaging is carried out to obtain the finished product. Among them, a water column is formed above the contact between the rubber roller and the melt, and a water film is formed at the contact between the melt and the rubber roller; The diameter of the water column is 0.5-3 mm.

2. The method according to claim 1, characterized in that The operation of uniformly coating water on the surface of the rubber roller to form a water coating layer is completed by a precision slit coating die.

3. The method according to claim 1, characterized in that The diameter of the water column is 1-2 mm.

4. The method according to claim 1, characterized in that: The surface tension of the water is 32-58 mN / m.

5. The method according to claim 1, characterized in that 0.5 wt% to 2 wt% of a surfactant is also added to the water.

6. The method according to claim 5, characterized in that The surfactant is any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyvinyl alcohol, hexadecyl alcohol polyoxyethylene ether, and ethanol.

7. The method according to claim 1, characterized in that The surface dyne value of the rubber roller is 35-60 mN / m.

8. Use of the method according to any one of claims 1 to 7 in preparing a plastic film, characterized in that: The production speed using this method reaches over 40m / min.

9. The use according to claim 8, characterized in that: After adopting this method, the service life of the rubber roller reaches more than 1.1 million meters.

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