Some standard content:
HG/ T 2902 -1997
This standard is not equivalent to ASTMD1457--92 "Standard Specification for Polytetrafluoroethylene Molding and Extrusion Materials". The main technical differences between this standard and ASTMD1457--92 are as follows: The volume density of the resin in this standard is 500#/1.±100g/L, while that of ASTM1457 is 675g/±50g/L; The average particle size of the resin in this standard is 180um±80μm=375m±75μm of ASTMD1457; The melting point of the resin in this standard is 327C±5, while that of ASTMD1457 is 327C±10; The tensile rate in the standard test method is 100mm/min, while that of ASTMI1457 is 50mm/min; This standard adds two indicators, cleanliness and electrical strength. The previous version of this standard is GB/T7136-86 "General-purpose polytetrafluoroethylene resin for molding". The difference from the previous version is: the name of the standard "General-purpose polytetrafluoroethylene resin for molding" is changed to "polytetrafluoroethylene resin for molding"; the "!" is added. Standard, definition, etc. Chapter: In the cleanliness index, the standard product b* no black center of 57mm rod is changed to no obvious color difference in the cross section of 57mm rod; the determination of standard relative density and general relative density adds "the result is averaged"; in the inspection rules, add "inspection is in batches" and "inspection is divided into factory inspection and type inspection". From the date of implementation of this standard, the original national standard GB/T7136--86 "General-purpose polytetrafluoroethylene resin for molding" is abolished. This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Plastic Resin Product Sub-Technical Committee (SC4) of the State Plastics Standardization Technical Committee. The responsible drafting unit of this standard is Shanghai San Ai Fu New Materials Co., Ltd. The main drafters of this standard are Cai Yonglian and Wu Yulin. ICS83.080.20
Record number 422-1997
Chemical Industry Standard of the People's Republic of China
Polytetrafluoroethylene resin for molding
Polytctrafluorocthylene molding powder1 Scope
HG/T2902--1997
This standard specifies the definition, requirements, test methods, inspection rules, marking, packaging, storage and transportation of polytetrafluoroethylene resin for molding.
This standard applies to polytetrafluoroethylene resin for molding produced by float polymerization. 2 Reference standards
The provisions contained in the following standards are constituted as provisions of this standard by citing them in this standard. When this standard is updated, the versions shown are valid. All standards will be revised. All parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T1033--S6 Test method for density and relative density of plastics GB/T1039--92 General principles for test methods for mechanical properties of plastics GB/T1040--92 Test method for tensile properties of plastics (ncgISO/R527--66) GB1408-89 Test method for power frequency electrical strength of solid insulating materials GB 2918--82 (89)
Standard environment for material sample state adjustment and test (ey1SO291-77)GH/T6678-86 General rules for chemical product mixing HGT2899-1997 Nomenclature of polytetrafluoroethylene materials Test method for bulk density of polytetrafluoroethylene resin IIG/T2900--1997
HGT2901-1997 Test method for particle size of polytetrafluoroethylene resin 3 Definitions
This standard adopts the following definitions:
3.1 Bulk density dcnsity
Resin mass obtained by shearing under test conditions (g) 32 Standard relative density standardiuspecilicgavity Frame relative density obtained from a polytetrafluoroethylene resin specimen molded and sintered according to this standard method, 3 General relative density extendedspceificoravity Specimen relative density measured by a polytetrafluoroethylene resin specimen molded according to this standard method after a long sintering time, the sintering time being longer than the sintering time given in this standard for the determination of standard relative density, 3.4 Preforming
The process of compacting powdered polytetrafluoroethylene resin into a solid in a mold. 3.5 Sintering
The heat treatment process used for polytetrafluoroethylene resin preforms, in which the polytetrafluoroethylene resin is melted and solidified by recrystallization during cooling.
Ministry of Chemical Industry of the People's Republic of China, 1997-05-23, 1997-10-01 Implementation
HG/T29021997
3.6 Thermal instability index thermalinstabilityindex indicates the degree of molecular weight decrease of polytetrafluoroethylene resin after prolonged heating and cooling according to the specified period. Requirements
According to the provisions of HG/T2899, the average particle size of the polytetrafluoroethylene resin produced by float process integration is 100μm~260um, and the volume density is 400g/L-500g/L. The molding polytetrafluoroethylene resin is FTFESM031. The technical requirements of PTF SM031 shall comply with the provisions of Table 1. Table 1 Technical requirements
Clarity
Tensile strength, MPa
Elongation at break, %
Volume density, /L
Average particle size, um
Water content, %
Refining point.
Standard relative density
Thermal instability index
Electric strength, MV/m
5 Test method
5.1 Sampling
Qualified products
. Surface treatment, uniform texture, no belt surface allowed, clean surface, uniform texture, no quality inspection
Metal impurities, less than or equal to
b. Diameter 57mum, no obvious color difference in the cross section 25.5
1mm impurities shall not exceed these 2
500±100
180±80
327±5
2. 13 ~2. 18
Sampling shall be carried out in accordance with GB/T6678. The number of sampling units shall be as specified in Table 2 of GB/T6678--86. The sampling unit shall be a packaging barrel in which an equal amount of sample is extracted from each package, mixed evenly, and placed in a clean and dry container. The sample shall be kept clean and dry to prevent the introduction of impurities such as water vapor and dust. Sampling is allowed to be carried out on the production line or in the sealing process to extract uniform and representative samples. Indicate the manufacturer name, product name, model, batch number and sampling date on the sample container. 5.2 Preparation of test samples
5.2.1 Kitchen slice test sample
Weigh 14.5 g of polytetraoxyethylene resin that has passed a 0.9 mm (20) gold sieve and add it evenly into the cavity of a smooth and clean mold. After scraping and closing the mold, place it on the lower plate of a hydraulic press and slowly pressurize it. Maintain the pressure at 34.5 MPa for 3 minutes, release the pressure, take out a preform with a diameter of 76 mm from the mold cavity, smooth the burrs, wipe it clean, and cast the product on a flat metal plate. Then, send it into a sintering furnace with forced hot air circulation and a rotating working plate, increase the temperature and sinter it according to the A method in 2. 32
HG/T2902—1997
5.2.2 Standard relative density and thermal instability index test sample Weigh 12.0±0.1g of polytetrafluoroethylene resin that passes through a metal sieve with a diameter of 0.9mm (20 turns), pour it into the cavity of a cylindrical mold with an inner diameter of 28.6mm and a height of at least 76mm, scrape the upper surface, and after closing the mold, place the mold in a hydraulic press and gradually pressurize it to a pressure of 34.5MPa, maintain the pressure for 2min, release the pressure, take out the colored product from the mold cavity, smooth the burrs, wipe it clean, place the colored product on an appropriate tray, and send it into its strong In a sintering furnace with hot air circulation and a rotating working disk, the standard relative density sample is sintered according to the A method in Table 2: the general relative density sample used to determine the thermal instability index is sintered according to the C method in Table 2. 5.2.3 Film test
Weigh 300g of tetrachloroethylene resin that passes through a metal sieve with a pore size of 0.9mm (20 meshes), and evenly add it into the mold cavity of a double-sided pressed mold with an outer diameter of 57mm and an inner diameter of 18mm. After scraping and closing the mold, put it on the lower plate of the hydraulic press and pressurize it. The initial pressure is 3.4sMPa and the pressure is maintained for 1min~2min. Then, it is steadily raised to 34.5MPa within 3min~5min. After maintaining the pressure for 2min~5min, the pressure is released, and the preform is taken out from the vertical direction of the mold cavity, the burrs are smoothed, wiped clean, and sent to a sintering furnace with forced hot air circulation and a rotating working disk, and the temperature is raised and sintered according to the B method in Table 2. The sintered rough pieces are placed at room temperature for more than 24 hours and then turned into a film with a thickness of 45 μm ± 5 μm using a special tool. 5.2.4 Rod-shaped specimen with a diameter of 57 mm
Weigh 400 g ± 50 g of polytetraoxyethylene resin that has passed through a metal sieve with a pore size of 0.9 mm (20), and evenly place it into the cavity of a double-sided pressed mold with a diameter of 57 mm. Press and sinter according to the method in 5.2.3 of this standard. The sintering conditions of each specimen are shown in Table 2.
Starting temperature, ',
Heating rate, /h
Hot-keeping temperature, ℃
Holding time, min
Cooling rate, C/h
Second holding temperature, C
Second holding time, min
Cooling time to room temperature, h
“Starting temperature before rising
Table 2 Sintering conditions of samples
@76mm disc and standard relative density sample
120±10
380±6
294±6
．“The second holding time is determined by each manufacturer. B
Φ57mm ladder test sample
60 ±5
371±6
240±15
238±6
General relative density test sample
120±10
380±6
360±5
60±5
294±6
24.0*g.1
5.3 Cleanliness test
5.3.1 The test of a in Table 1 is to take 4 samples prepared according to 5.2.1 of this standard. The cleanliness of the samples is visually tested under the transmission of 20W~40W fluorescent lamp. The distance between the sample and the lamp is 10cm~15cm, and the test result is graded based on the worst one. 5.3.2 The test of b in Table 1 is to take a piece of material prepared according to 5.2.4 of this standard, cut it horizontally from the middle, and visually inspect its cross-section color. 5.4 Determination of tensile strength and elongation at break 5. 4.1 Specimen
HG/T 2902 —1997
The mesh punching tensile specimen prepared according to 5.2.1 of this standard has the dimensions shown in Figure 1. The thickness deviation of the same specimen is not more than ±0.1mm. Each group of specimens is not less than 5. 5
1 Dimensions of tensile specimens
Test conditions
The test environment temperature is 23℃ ±2℃;
The test tensile speed is 100mm/min±10mm/min. 5.4.3
Operation steps
24mm,
The specimen is adjusted at 23°C±2°C for at least 2 hours according to GB2918. The specimen is tested according to the method specified in GB/T1040. The fixture holds the two ends of the specimen, symmetrically in the upper and lower positions, with a spacing of 5.4.4
Results
The tensile strength is calculated according to GB/T1040, and the elongation at break is calculated according to formula (1):
Where: e——elongation at break, %;
L Initial length of specimen, mm;
Length of specimen at break, m,
× 100
The test results are expressed as the arithmetic mean of each group of specimens. The deviation between the measured value of each specimen and the average value shall not exceed ±10%. If it exceeds ±10%, it shall be discarded. After discarding, the remaining specimens shall not be less than 3. 5.5 Determination of bulk density
Determine according to the provisions of HG/T2900
5.6 Determination of average particle size
Determine according to the provisions of HG/T2901.
5.7 Determination of moisture content
Instruments and equipment
a) Electric constant overflow vacuum drying oven, vacuum degree less than: 95.BkPa; b)
Vacuum pump, limit strength less than 1.3 Pai
Analytical balance, sensitivity 0.1mg;
Aluminum weighing pan, 5mL needle box,
5.7.2 Operation steps
Accurately weigh 35g~40g of polytetraoxyethylene resin (accurate to 0.0001g) in a constant-weight aluminum weighing tube with a lid, weigh 34
HG/T 2902-1997
Put it in a vacuum drying oven and dry it for 1.5 hours at an absolute pressure of 13.3ka and a humidity of 150±1. Take it out of the drying oven, cover it, and put it in a dryer to cool for at least 30 minutes. Weigh it again and calculate the mass loss of the resin during the drying process. 5.J.3 Result Expression
The moisture content is calculated according to formula (2)
m, -m,
Where: X-moisture content, %
m,-resin before drying. The mass of the weighing pan and cover, g;-the mass of the weighing pan and cover,,,
-the mass of the resin, weighing pan and cover after drying, more. X100
The arithmetic mean of two samples measured in parallel is taken as the test result. The difference between the two is not greater than 0.3%. 5.8 Determination of melting point
5.8. Instrument
Differential scanning calorimeter (DSC)
5.8.2 Operation steps
Weigh about 8 mg of polytetrafluoroethylene resin, seal it in a lead crucible and use a blank aluminum crucible as a reference. , heating to 380℃ at a heating rate of 10℃/min, then cooling to 240℃ at a cooling rate of 10℃/min, and then heating to completely melt the polyvinyl fluoride resin at a heating rate of 10℃/min, and taking the peak intensity of the second melting peak as the melting point of the polyvinyl fluoride resin. 5.9 Determination of standard relative density
Use two samples prepared according to 5.2.2 and measure them according to the provisions of GB/T1033-86A method, and take the average value of the results. 5.10 Determination of thermal instability index
5.10.1 Determination of generalized relative density
Take two samples prepared according to 5.2.2 and measure them according to the provisions of GB/T1033-86A method, and take the average value of the results. 5.10.2 Nesting expression
The thermal instability index is calculated according to formula (3): T1I (ESG - SSG) × 1 000
Wherein: T11——- Thermal stability index; ESG——- Generalized relative density;
SSG—— Standard relative density
5.11 Determination of electrical strength
This method uses a continuous and uniform voltage increase to apply a DC voltage to the sample until it breaks through, and then the breakdown voltage value is measured to calculate the electrical strength of the sample.
S.11.1 Sample
Prepared according to 5.2.3 of this standard, the film is 45um±5um thick and 1m long. 5.11.2 Device
Automatic high-voltage breakdown device, the current waveform distortion rate is less than 5%; a)
The electrode is the electrode shown in Figure 1 (a) of GB1408-89: the thickness gauge accuracy is 0. 001mm
5. 11.3 Test conditions
According to the normal temperature and humidity conditions in GB2918, 35
5. 11.4 Operation steps
HG/2902-~1997
The sample G is conditioned in the normal temperature and humidity environment in GB2918 for 2h. Place a thin film between two electrodes, and evenly increase the voltage at a rate of 1& per second until it breaks down. Record the instantaneous breakdown voltage value, and randomly select 10 points for measurement. Measure the thickness of each breakdown point of the sample, and take the average value of each point after 3 measurements. The thickness measurement error is set to be no more than
518.5 Result expression
According to the provisions of G1408. The test results are expressed as the arithmetic mean of the 10 points, and take two significant figures. Gross inspection rules
6, is the inspection is based on batches, the manufacturer produces one batch of resin, no mixing is allowed, 6. Each batch of products must be inspected by the quality inspection department of the manufacturer, and it is guaranteed that all products leaving the factory meet the requirements of this standard. Each batch of products should have a quality inspection report. bzxz.net
6.3 Inspection is divided into factory inspection and control inspection. In Table 1, (1) solubility (2) tensile strength, (3) elongation at break are the required test items for each batch, and the pump is the sampling inspection item, and the following (6) moisture content, (8) standard relative density, (9) thermal instability index, at least one item is sampled for every 30 batches; (1) solubility index b, (4) bulk density, (5) average particle size, (10) electrical strength, at least one item is sampled for every 50 batches; (7) melting point, at least one item is sampled every year. The inspection shall be carried out in accordance with the provisions of 6.6.1 of GB/T1.3-87.64 The user has the right to inspect and accept the products received in accordance with the provisions of this standard. The inspection shall be carried out within one month of receiving the products.
6.5 Inspection results If any index does not meet the requirements of this standard, double samples should be randomly taken from the batch of products to re-test the unqualified items. If the re-test results still do not meet the requirements of this standard, the batch of products is unqualified. 66 When the supply and demand parties have objections to the product quality, they can negotiate to resolve or the statutory quality inspection department can conduct arbitration. Labeling, packaging, storage and transportation
7.1 Marking
The packaging of this product should have firm and clear markings, indicating the manufacturer, product name, model, grade, net content, batch number or production date and this standard number
7.2 Packaging
This product should be packaged in two layers of plastic bags and packed in hard barrels, with a net content of 25k per barrel. Each packaging barrel should be accompanied by a product certificate
7.3 Storage and transportation
This product is transported as non-dangerous goods and should be protected from moisture and severe vibration during transportation. This product should be stored in a clean, cool and dry warehouse to prevent dust, moisture and other debris from entering.
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