Special process for producing PET plastic plate
阅读说明：本技术 专用于生产pet塑料板的工艺方法 (Special process for producing PET plastic plate ) 是由 刘福华 于 2020-07-04 设计创作，主要内容包括：本发明提供一种专用于生产PET塑料板的工艺方法,所述工艺包括：投料；烘干,去除水分：塑化挤出,采用特定温度分三区加热机筒,采用特定结构的PET炮筒螺杆以及特定挤出速度；成型/定型,压缩成型区分为四区进行恒温,定型区对熔料不断降温,最后凝固结晶定型被挤出；保温热处理,三段热处理；切板。本发明能够减少产品内应力,避免收缩或开裂报废,制品内部几无气孔杂质。(The invention provides a special process method for producing a PET plastic plate, which comprises the following steps: feeding; drying and removing water: plasticizing and extruding, namely heating a machine barrel in three zones at a specific temperature, and adopting a PET gun barrel screw rod with a specific structure and a specific extrusion speed; molding/shaping, namely dividing the compression molding area into four areas for constant temperature, continuously cooling the molten material in the shaping area, and finally solidifying, crystallizing and shaping to be extruded; heat preservation heat treatment, three-stage heat treatment; and (5) cutting the plate. The invention can reduce the internal stress of the product, avoid shrinkage or cracking and scrap, and the product has few air hole impurities inside.)
1. A process method special for producing a PET plastic plate is characterized by comprising the following steps:
drying: drying the PET plastic granules by circulating hot air at 130 ℃ to ensure that the moisture content of the PET plastic granules is lower than 0.2%;
plasticizing and extruding: the PET plastic granules are converted into uniform continuous melt with certain fluidity to be extruded through the action of the temperature of a machine barrel and an extrusion screw; wherein, divide into three district and heat to the barrel around:
the temperature of the feeding section in the first area is 230 ℃ and 250 ℃;
the temperature of the second-zone melting compression section is 250-260 ℃;
the temperature of the three-zone homogenization section is 240 ℃ and 250 ℃;
joint 250-260 ℃;
the extrusion screw is a special PET gun barrel screw with equal-distance gradual change, the length-diameter ratio of the screw is 28: 1, the compression ratio is 3.2, and the extrusion speed is 14-16 r/min;
molding/shaping: under the rotary extrusion of the extrusion screw, the fluid uniform melt enters a machine head through a porous plate, is molded and shaped according to a parison with a certain shape and is extruded out of a die; wherein
The compression molding area of the die is divided into four areas for constant temperature:
the temperature of the former zone is 230-240 ℃;
the temperature of the first two areas is 250-260 ℃;
the temperature of the latter zone is 240 ℃ and 250 ℃;
the temperature of the second zone is 250-260 ℃;
the shaping area of the mould continuously cools the melting material, and finally the melting material is solidified, crystallized and shaped and is extruded out of the mould;
heat preservation and heat treatment: carrying out three-stage heat treatment on the product, wherein the first zone is 160 ℃, the second zone is 140 ℃ and the third zone is 120 ℃;
cutting a plate: and cutting the formed plate into a preset length.
2. The process for producing PET plastic sheets as claimed in claim 1, further comprising a post heat treatment step after the cutting of the sheets:
carrying out heat treatment on the stacked PET plates, and dividing the PET plates into eleven sections:
3. the process specific for the production of PET plastic sheets according to claim 1 or 2, characterized in that after said shaping/setting, it further comprises:
braking: the plate forms certain resistance through braking, so that the thickness and the eccentricity of the plate are adjusted.
4. The process specific for the production of PET plastic sheets as claimed in claim 3, further comprising, after said heat-preserving heat treatment:
traction: and drawing the plate subjected to heat preservation and heat treatment by using a drawing mechanism so as to enable the melt to form certain pressure in the compression molding area, so that the structural compactness of the plate is improved, and the thickness of the plate is adjusted to achieve eccentricity.
Technical Field
The invention relates to a special process method for producing a PET plastic plate.
Background
The PET (Polyethylene terephthalate) plate is extruded and molded by adding granular materials into a machine barrel of an extruder from a hopper, conveying and compacting the materials forwards under the extrusion pushing action of the rotation of a screw rod through the friction action of the inner wall of the machine barrel and the surface of the screw rod, preheating through a heating device and friction outside the machine barrel, and melting and plasticizing under the conditions of high temperature and high pressure. Then, the continuously rotating screw pushes the molten material into a head die, and the molten material extruded from the head die is cooled and shaped into the required PET product.
The PET plate forming process comprises the following steps: feeding, drying, plasticizing extrusion, molding and shaping, cutting into plates, chamfering and the like, wherein in the plasticizing extrusion process, a machine barrel needs to be heated, and in the molding and shaping process, the constant temperature needs to be kept.
In the prior art, in the process of preparing a PET plate, 110 ℃ circulating hot air is adopted to dry PET in a drying stage, so that the moisture content in the product is lower than 0.3%; the plasticizing extrusion time is divided into three sections to heat the machine barrel:
the temperature of the feeding section in the first area is 260 ℃ and 280 ℃;
the temperature of the second-zone melting compression section is 230-240 ℃;
the temperature of the three-zone homogenizing section is 220-230 ℃;
the joint temperature is 230-240 ℃;
the length-diameter ratio of the screw is 15: 1, the compression ratio is 2.5, and the extrusion speed is 20-25 r/min.
And (3) keeping constant temperature in four zones during compression molding:
temperature of the former zone: 250 ℃ and 260 ℃;
temperature in the first two zones: 270 ℃ and 280 ℃;
temperature in the latter zone: 220 ℃ and 230 ℃;
temperature in the second zone: 230 ℃ and 240 ℃.
The heat treatment is divided into nine sections:
a first stage: the heating temperature is 60 ℃, and the heating time is about 20 minutes;
and a second stage: the constant temperature is 100 ℃, and the constant temperature time is about 3-120 minutes;
a third stage: the heating temperature is 80 ℃ and the heating time is about 40 minutes;
a fourth stage: the constant temperature is 70 ℃, and the constant temperature time is about 120 minutes;
a fifth stage: the heating temperature is 70 ℃, and the heating time is about 20 minutes;
a sixth stage: the constant temperature is 60 ℃, and the constant temperature time is about 120 minutes;
a seventh stage: the heating temperature is 60 ℃, and the heating time is about 20 minutes;
an eighth stage: the constant temperature is 70 ℃, and the constant temperature time is about 10 minutes;
a ninth stage: the temperature is reduced to 60 ℃ for about 10 minutes.
The PET plate prepared by the process has the advantages of large internal stress, shrinkage deformation, low yield, serious waste, more internal pore impurities and influence on quality.
Disclosure of Invention
In view of the above, there is a need to provide a special process for producing PET plastic plate, which can reduce the internal stress of the product, avoid shrinkage or cracking and scrap, and have few pore impurities inside the product.
The invention provides a special process method for producing a PET plastic plate, which comprises the following steps:
feeding;
drying: drying the PET plastic granules by circulating hot air at 130 ℃ to ensure that the moisture content of the PET plastic granules is lower than 0.2%;
plasticizing and extruding: the PET plastic granules are converted into uniform continuous melt with certain fluidity to be extruded through the action of the temperature of a machine barrel and an extrusion screw; wherein, divide into three district and heat to the barrel around:
the temperature of the feeding section in the first area is 230 ℃ and 250 ℃;
the temperature of the second-zone melting compression section is 250-260 ℃;
the temperature of the three-zone homogenization section is 240 ℃ and 250 ℃;
joint 250-260 ℃;
the extrusion screw is a special PET gun barrel screw with equal-distance gradual change, the length-diameter ratio of the screw is 28: 1, the compression ratio is 3.2, and the extrusion speed is 14-16 r/min;
molding/shaping: under the rotary extrusion of the extrusion screw, the fluid uniform melt enters a machine head through a porous plate, is molded and shaped according to a parison with a certain shape and is extruded out of a die; wherein
The compression molding area of the die is divided into four areas for constant temperature:
the temperature of the former zone is 230-240 ℃;
the temperature of the first two areas is 250-260 ℃;
the temperature of the latter zone is 240 ℃ and 250 ℃;
the temperature of the second zone is 250-260 ℃;
the shaping area of the mould continuously cools the melting material, and finally the melting material is solidified, crystallized and shaped and is extruded out of the mould;
heat preservation and heat treatment: carrying out three-stage heat treatment on the product, wherein the first zone is 160 ℃, the second zone is 140 ℃ and the third zone is 120 ℃;
cutting a plate: and cutting the formed plate into a preset length.
Further, the method also comprises a post heat treatment step after the plate cutting:
carrying out heat treatment on the stacked PET plates, and dividing the PET plates into eleven sections:
further, after the forming/shaping, the method further comprises the following steps:
braking: the plate forms certain resistance through braking, so that the thickness and the eccentricity of the plate are adjusted.
Further, after the heat-preserving heat treatment, the method further comprises the following steps:
traction: and drawing the plate subjected to heat preservation and heat treatment by using a drawing mechanism so as to enable the melt to form certain pressure in the compression molding area, so that the structural compactness of the plate is improved, and the thickness of the plate is adjusted to achieve eccentricity.
By selecting the process steps and setting the process parameters, the invention overcomes the shrinkage deformation or cracking scrap caused by overlarge internal stress of the plate, avoids the defect of serious waste, ensures the quality of the product because the product has few air-hole impurities inside, and greatly improves the yield of qualified products.
Drawings
Fig. 1 is a schematic structural view of a production apparatus according to an embodiment of the present invention.
Detailed Description
The process method provided by the invention is specially used for producing the PET plastic plate, and the PET plastic plate is produced by the PET special production equipment shown in figure 1. As shown in figure 1, the equipment comprises a motor 1, a reduction gearbox 2, a hopper 3, a dryer 4, a control cabinet 5, a PET special barrel screw 6, a flange joint 8, a mould 9, a mould frame 12, a
The motor 1, the reduction gearbox 2, the hopper 3, the dryer 4, the control cabinet 5, the PET special gun barrel screw 6 and the like can form a main machine part of the equipment, and the mold 9, the
The motor 1 and the reduction gearbox 2 form a rotating system, the motor 1 runs and drives the reduction gearbox 2 through belt transmission, and therefore the PET special gun barrel screw 6 keeps a certain shearing rate. The special parameters of the PET special barrel screw 6 are as follows: the length-diameter ratio is 25: 1, compression ratio of 3.3.
The machine cabinet can be internally provided with a control system which specifically comprises an electrical instrument and an actuating mechanism and is mainly used for controlling the main machine, so that the rotating speed and the power of the operation of the main machine are normal, the temperature, the pressure, the flow and the quality of products of the main machine and the auxiliary machine are ensured, and the automatic control of the whole machine set is realized.
The die 9 comprises an upper die, a
The water temperature machine for providing the circulating cooling water is arranged at the upper and lower die shaping sections, and the shaping water temperature is controlled by circulating hot water, so that the products in the shaping area are shaped at a constant and balanced temperature and are smoothly extruded out of the die 9.
The heat preservation device 13 mainly comprises an upper steel plate, a lower steel plate and a support thereof, the upper steel plate and the lower steel plate are heated by using a heating plate, a product passes through the upper steel plate and the lower steel plate, the product is subjected to heat treatment at a certain temperature, partial internal stress of the plate is eliminated, the flatness of the product is ensured, and the warping phenomenon is greatly improved.
The
The cutting machine 15 is a plate cutting device and is arranged behind the outlet of the die 9, the extruded product passes through the plate cutting supporting surface of the plate cutting machine, and the plate is cut into products with required lengths through the high-speed rotation of the saw blade.
The oven is of a sealed box body structure, different temperatures are set through a temperature controller, heat treatment is carried out on the product at different time and in different sections, residual internal stress of the product is eliminated, and product quality and stability are guaranteed.
The invention provides a special process method for producing a PET plastic plate, which mainly comprises the following steps: feeding, drying, plasticizing and extruding, molding/shaping, braking, heat preservation and heat treatment, traction, plate cutting, stacking, heat treatment and edge chamfering.
The following focuses on the specific process steps of one embodiment of the present invention.
1. Feeding: when feeding, the material should be fed in time, the hopper 3 is guaranteed not to be empty, different materials cannot be used in a mixed mode, the grade of the material is distinguished, the type of the material is noticed, and sundries are prevented from entering the hopper 3 to cause the blockage of a feed opening.
2. Drying: because the PET resin has high temperature absorption, the PET resin needs to be dried before extrusion molding to remove moisture, otherwise, the moisture content exceeds a certain limit, and the moisture can volatilize into gas in an extruder barrel, so that air holes are contained in the product, and the strength of the product is reduced.
In the step, aiming at the characteristics of the PET plastic grains, the PET plastic grains are dried by 130 ℃ circulating hot air, so that the moisture content of the PET plastic grains is lower than 0.2%, and the preheating effect of the PET plastic grains is realized while the 130 ℃ circulating hot air is adopted to dry the PET plastic grains, thereby being beneficial to later-stage plasticization.
3. Plasticizing and extruding: the PET plastic granules are converted into a uniform continuous melt with certain fluidity by the action of the temperature of a cylinder and an extrusion screw and are extruded.
The extrusion screw is a special PET gun barrel screw with equal-distance gradual change, the length-diameter ratio of the screw is 25: 1, compression ratio of 3.3.
Wherein the barrel is heated by dividing the front and rear sections into three zones, and the temperature of the feeding section in one zone is 230-; the temperature of the two-zone melting compression section is 250-; the three-zone homogenization zone temperature is 240 ℃ and 250 ℃ (e.g., 241 ℃, 242 ℃, 243 ℃, 244 ℃, 245 ℃, 246 ℃, 247 ℃, 248 ℃, 249 ℃); the extrusion speed of the joint 250 and 260 ℃ (such as 251 ℃, 252 ℃, 253 ℃, 254 ℃, 255 ℃, 256 ℃, 257 ℃, 258 ℃ and 259 ℃) is 14-16r/min (such as 15, 16 and 17 r/min).
By selecting a specific screw length-diameter ratio, a specific compression ratio, a specific three-zone heating temperature, a specific joint temperature and a specific extrusion speed, PET plastic granules can be more completely plasticized, melted and extruded to form a shape, and the setting of each parameter influences the stress, air holes, mechanical properties and the like of a plate product.
4. Molding/shaping: under the rotary extrusion of the extrusion screw, the fluid uniform melt enters the machine head through the porous plate, is molded and shaped according to a parison with a certain shape, and is extruded out of the die 9.
The die 9 is divided into a compression molding area and a shaping area, the first third of the die 9 is the compression molding area, and the second third of the back of the die 9 is the shaping area.
The compression molding zone of the mold 9 is divided into four zones for constant temperature, and the temperature of the former zone is 230-; the temperature of the first two zones is 250-260 deg.C (such as 251 deg.C, 252 deg.C, 253 deg.C, 254 deg.C, 255 deg.C, 256 deg.C, 257 deg.C, 258 deg.C, 259 deg.C); the temperature of the latter zone is 240 ℃ and 250 ℃ (e.g., 241 ℃, 242 ℃, 243 ℃, 244 ℃, 245 ℃, 246 ℃, 247 ℃, 248 ℃, 249 ℃); the temperature of the second zone is 250 ℃ and 260 ℃ (such as 251 ℃, 252 ℃, 253 ℃, 254 ℃, 255 ℃, 256 ℃, 257 ℃, 258 ℃ and 259 ℃).
The shaping area of the mould 9 continuously cools the melting material and finally solidifies, crystallizes and shapes the melting material and is extruded out of the mould 9. The two ends of the shaping area of the mould 9 are both connected with cooling circulating water, and the temperature of the melting materials is continuously reduced through the continuous circulation of cold water.
5. Braking: the plate is clamped to form certain resistance by adjusting the tightness of the brake strip of the brake seat 11, and the thickness and the eccentricity of the plate can be adjusted by adjusting the tightness of the brake.
6. Heat preservation and heat treatment: the product was subjected to three stages of heat treatment, the first zone being 160 ℃, the second zone being 140 ℃ and the third zone being 120 ℃.
7. Traction: the outlet position of the heat preservation device 13 is provided with another brake seat 11, the brake seat 11 is used for adjusting the tightness of the brake strip to clamp the plate product, and the
8. Cutting a plate: 1000MM length is measured by a measuring tape, and a plate cutting machine is started to cut out the required length.
9. Stacking: hoisting the plate by using a sucker to hoist the block, and neatly stacking the plate on a specific stacking frame; three stainless square steels are placed between the plates, the square steels between layers appearing preferably on top and bottom in a straight line.
10. And (3) post heat treatment: the PET panel that stacks through the oven carries out heat treatment, divide into eleven sections:
through the specific later stage heat treatment steps, the PET plate product is subjected to specific temperature heat treatment in specific time and multiple sections, so that the residual internal stress of the PET plate product can be effectively eliminated, and the quality and the stability of the PET plate are ensured.
11. Chamfering: each edge of the plate is chamfered, so that the product is more attractive, and fingers can be prevented from being cut by the diamond edge of the plate in the carrying process.
The PET panels were tested, with the following test items and results:
item
Standard of merit
Unit of
Numerical value
Density of
ASTM D792
g/cm3
1.4
Tensile strength at yield
ASTM D638
Mpa
80
Elongation at break
ASTM D638
％
3.5
Bending strength
ASTM 790
Mpa
200
Flexural modulus
ASTM 790
Mpa
4000
Impact strength
ASTM D256
J/M
60
The above specific parameters are parameters which are finally determined by the inventor of the invention through repeated large amount of specific experiments and take several years and are suitable for producing the PET plastic plate, the parameters are interdependent but not isolated, the parameters are matched together to finally obtain the expected PET plastic plate, through the steps of the above specific process method, the prepared PET plastic plate overcomes the defects of shrinkage deformation or cracking scrapping caused by overlarge internal stress, the defect of serious waste is avoided, no air hole impurities exist in the product, the quality of the product is ensured, and the yield of qualified products is greatly improved.
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