Some standard content:
National Standard of the People's Republic of China
Polyethyiene blown film for agriculture
Polyethyiene blown film for agricultureSubject content and scope of application
GB4455-94
Replaces GR445584
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of polyethylene blown film for agriculture. This standard applies to polyethylene blown film for agriculture (hereinafter referred to as film) made by blow molding with low-density polyethylene resin (LDPE) or a blend of low-density polyethylene resin and linear low-density polyethylene resin (IIDPE) as the main raw materials. 2 Reference standards
Batch inspection counting sampling procedure and sampling table (applicable to inspection of continuous batches) GB 2828
GB 2918
Standard environment for conditioning and testing of plastic specimens-Determination of thickness of plastic film and sheeting-Mechanical measurement method GB 6672
GB 6673
Determination of length and width of plastic film and sheeting GB13022
Test method for tensile properties of plastic film
QB/T 1130
3 Technical requirements
Test method for right-angle tearing properties of plastics
Width and deviation shall comply with the requirements of Table 1.
Width (folded diameter)
Superior product
1 001~1 500
1 501~2 500
2 501~3 500
3 501~5 000
Thickness and limit deviation shall conform to the requirements of Table 2. Approved by the State Bureau of Technical Supervision on July 6, 1994, qualified products. Implementation on February 1, 1995. 0.050, 0.060, 0.070, 0.080, 0.090, 0.100, 0.110, 0.120, 0.130, 0.140, 0.070, 0.080, 0.090, 0.100, 0.110, 0.120, 0.130, 0.140, 0.140. GB 4455-94
Superior product
Thickness limit deviation
-Qualified product
Note: For films with a width greater than 1500mm, qualified products are allowed to have a thickness deviation of ±0.005mm, and its width is less than 20mm, and there shall be no more than two places. 3.1.3 The average thickness deviation shall meet the requirements of Table 3. Table 3
Thickness.mm
0.030~0.140
Appearance should meet the requirements of Table 4
Watermarks and clouds
Bubbles, perforations and ruptures
Impurities, pieces/m2
Fish eyes and micro-blocks, pieces/m2
Wrinkles and ribs
Separation line
Superior products
Average thickness deviation, %www.bzxz.net
First-class products
Superior products
0. 3~0. 6 mm
0. 6~2. 0 mm
Not obvious
Qualified products
First-class products, qualified products
Does not affect the use
0. 3~~0. 6 mm
0. 6~2. 0 mm
Minor, flat tearing should not be in a straight line
Does not affect use
Broken ends per roll, pieces
Minimum length of each section, m
GB 4455-94
Continued Table 4
Superior products
Reference length should be marked on each roll of film, and the net mass and weighing deviation should meet the requirements of Table 5. Table 5
Width.mm
10011500
1 501 ～2 500
2 501~3500
3501~～~5 000
3.4 Physical and mechanical properties should meet the requirements of Table 6. Item
Tensile strength, longitudinal and transverse
Elongation at break, longitudinal and transverse
Net mass
≤100
Superior products
≥0.050 mm
Right-angle tear strength, longitudinal and transverse
Test method
4.1 Sampling method
≥300
≥350
Superior products, qualified products
Cannot affect use
Weighing deviation
-Superior products, qualified products
≥300
Cut 1m from the outer end of the film roll, and cut two pieces of film samples with a length of 1m, one of which is reserved. The sample is first tested for width and appearance, and then the sample is cut as shown in Figure 1. The first sample is for thickness testing, and the second sample is for physical and mechanical properties testing. The second sample is cut into test pieces as shown in Figure 2.
GB 4455—94
Unit: mm
First specimen; 2. Second specimen; 1
Width
Unit: mm
1Right-angle tear test piece 2Tensile test piece
4.2The standard environment for specimen state adjustment and testing shall be in accordance with the standard environment and normal deviation range in GB2918. The state adjustment time shall not be less than 4h. 4.3Width
Perform in accordance with GB6673.
4.4Thickness
Perform in accordance with GB6672.
Calculation and expression of results:
At= tmax (or tmin)-to
Where: △Thickness limit deviation, mm;
---Measured maximum thickness, mm
t ux--
Measured minimum thickness, mm;
I rtin
Average thickness deviation, %,
Electrical code
·（2）
4.5 Appearance
Average thickness, mm;
-Nominal thickness, mm.
GB 4455--94
4.5.1 Watermarks, clouds, bubbles, perforations, cracks, impurities, fish eyes and stiff blocks are visually inspected under natural light. The number of impurities, fish eyes and blocks shall be inspected according to the provisions of Table 4, and their values shall be measured with corresponding measuring tools. 4.5.2 Tear the stripes flat with the thumbs of both hands at a distance of 10mm. 4.6 Tensile strength and elongation at break
Perform according to GB13022. The specimen adopts type I in the standard. Test speed (no load): 500±50mm/min. 4.7 Right-angle tear strength
Perform according to QB/T1130, using a single specimen. 5 Inspection rules
5.1 Batch
The film is inspected in batches. The film produced continuously with the same brand of raw materials, the same formula and the same specifications is a batch of less than 50t.
5.2 Factory inspection
Factory inspection is all items in the technical requirements. 5.3 Sampling
Specifications and appearance are carried out according to the normal inspection secondary sampling plan in GB2828. Each roll of film is a sample unit, and the general inspection level II is adopted; the qualified quality level (AQL) is 6.5, see Table 7. Physical and mechanical properties are selected from any sample. Table 7
26～50
51～90
91～150
151~280
281~500
501~1200
1 201～~3 200
5.4 Judgment rules
5.4.1 Judgment of sample unit quality
Cumulative sample size
Qualified judgment number A.
Unqualified judgment number R.
GB4455-94
Specifications and appearance are inspected according to the requirements of 3.1 and 3.2. If all items are qualified, the sample unit is qualified. 5.4.2 Determination of the quality of the delivery batch
Specifications and appearance shall be carried out in accordance with GB2828, see Table 7. If there are unqualified items in the physical and mechanical performance test results, double samples shall be drawn from the original batch and the unqualified items shall be retested. If all the retest results are qualified, the batch is qualified. 5.4.3 Determination of product quality grade
Determine according to the lowest grade of all test results. 6 Marking, packaging, transportation, storage
6.1 Marking
Each roll of film shall be accompanied by a product certificate, which shall indicate: manufacturer name, factory address, product name, registered trademark, manufacturing date or production batch number, product specifications, grade, net mass, reference length, standard number, inspector's seal, etc. The packaging of each roll of film shall indicate: manufacturer name, factory address, product name, product specifications, net mass, etc. 6.2 Packaging
Each roll of film shall be wrapped and tied tightly with a film or kraft paper with a thickness of more than 0.08mm. If there are other special requirements, they shall be agreed upon by the supply and demand parties.
6.3 Transportation
Film shall be handled with care during transportation to prevent mechanical collision and sun and rain. 6.4 Storage
Film shall be stored in a clean, cool and dry warehouse, stacked neatly, and shall not be squeezed or damaged. The distance from the heat source shall not be less than 1m. The storage period shall not exceed one and a half years from the date of production. Additional Notes:
This standard was proposed by the China Light Industry General Association and is under the jurisdiction of the National Technical Committee for Standardization of Plastic Products. This standard was drafted by Tianjin No. 2 Plastic Products Factory. The main drafters of this standard are Zhong Ziqiang and Shao Keming. This standard refers to JIS K6781-1977 (confirmed in 1986) "Polyethylene Film for Agricultural Use". 5536
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