Plastic woven sack quality standard.
Standard of People’s Republic of China. GB/T 8946-1998
1. Range
This standard stipulates the product classification, technical requirements, test methods, inspection rules and marks, packaging, transportation and storage requirements of plastic woven bags. This standard is applicable to plastic woven bags (hereinafter referred to as bags) made of polypropylene and polyethylene resin as main raw materials, extruded and stretched into flat silk, then woven and bagged for packing powder or granular solid materials and flexible articles.
2. Standard reference
Provisions contained in the following standards constitute provisions of this standard by reference to this standard. At the time of publication of this standard, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards.
GB/T 1039-92 General Rules for Testing Method of Mechanical Properties of Plastics GB/T 1040-92 Testing Method for Tensile Properties of Plastics
GB/T 2828-87 Batch-by-Batch Inspection Sampling Procedure and Sampling Table (Suitable for Continuous Batch Inspection) Standard Environment for State Adjustment and Testing of Plastic Samples.
GB/T 4857.5-92 Test Method for Dropping of Packaging Transportation Packages GB/T 5009.60-1996 Polyethylene and Polyethylene for Food Packaging Method for analysis of hygienic standard for polystyrene and polypropylene mouldings.
GB 9687-88 Hygienic standard for polyethylene mouldings for food packaging
GB 9688-88 Hygienic standard for polypropylene mouldings for food packaging
3 Product classification
3.1 Shapes of bags
3.1.1
Polypropylene bags and polyethylene bags are classified according to their main components.
3.1.2 According to the sewing method, it can be divided into sewing bottom bag and sewing side bottom bag (see Figure 1).
sewing bottom bag sewing side bottom bag Figure 1
3.2 Types of bags
The
types of pp woven bags, allowable loading capacity, tape density, weaving density should meet the requirements of chart 1,
|
TYPE |
TA |
A |
B |
C |
|
CAPACITY |
10-20KGS |
21-30KGS |
31-50KGS |
51-60KGS |
|
TAPE DENSITY.TEX |
100 |
111 |
111 |
111 |
|
WARP*WEFT |
32×32 |
36*36 |
40*40 |
48*48 |
|
Remark: 1. 1tex=1g/km The technical specifications of flat yarn for plastic woven bags are shown in Appendix A (Appendix to Standards) 2. When the warp and weft density changed, the tensile strength in each direction must reach the target of the corresponding model product. |
||||
chart 1 3.3 Size of Woven bags
The effective width of the bag is divided into 450,500,550,600,650,700 mm width. If the effective width does not meet the above specifications, it shall be decided by the supplier and the buyer through consultation.
4. Technical requirements
4.1 Quality requirements on appearance.
|
Items |
Requirements |
|
Yarn broken |
Totally less than 3 for warp and weft on same position. |
|
Clearance |
Oil stains under 100mm² ≤ 3， Oil stains over 100mm² not allowed. |
|
Sewing |
Any Unneedle, broken thread, unstitched folding not allowed. |
|
Cutting |
Any scatter not allowed. |
chart 2
4.2 Tolerance allowed.
|
Item |
Tolerance allowed |
|
Length mm |
+15 -10 |
|
Width mm |
+15 -10 |
|
Warp tape/100mm |
-1 |
|
Weft tape/100mm |
-1 |
|
GSM % |
+8 -7 |
Chart 3 4.3 Physical property
Physical property should meets the requirements on Chart 4
|
|
|
TA |
A |
B |
C |
|
Tensile strength N/50mm |
Warp |
≥550 |
≥650 |
≥800 |
|
|
Weft |
≥450 |
≥550 |
≥650 |
≥800 |
|
|
Side sewing (Double thread) |
≥250 |
≥300 |
≥350 |
≥400 |
|
|
Bottom sewing(Double thread) |
≥200 |
≥250 |
≥300 |
≥350 |
|
|
Heat resistance |
Without abnormal conditions such as adhesion, melt marks, etc. |
||||
|
Drop test |
Bags do not break and contents do not leak. |
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Chart 4
4.4 Hygienic properties
Bags directly in contact with food and medicine should comply with GB 9687 or GB 9688.
5.Testing method
5.1Appearance inspection.
Visual inspection of appearance under natural light.
5.2Length and width
Flatten the bag. Measure three places in the middle and 100 mm away with a ruler accurate to 1 mm. The ruler should be parallel to the edge of the bag. The maximum deviation is taken as the test result.
5.3Weaving density
Flatten the bag, delineate 100 mm X 100 mm two diagonal blocks at the top and bottom of the bag. The outer edge of the square is 100 mm apart from the edge of the bag. Visually measure the number of longitude and latitude roots in the square, and take the average value. When the last edge is less than one, calculate it according to one.
5.4 Weight per unit area.(gsm)
5.4.1 Cut 4 pieces of sample of square meter 10000mm² each.
5.4.2 The mass is weighed by a balance with a sensitivity of 0.01 g, and its arithmetic average value is taken to calculate the mass deviation per unit area.
5.5 Tensile strength.
5.5.1 Testing condition refer to GB/T 1039.
Testing temperature 23℃±2℃， adjust 4h under normal humidity.
5.5.2 Testing equipment should meets the stipulation recorded in standard GB/T 1040-92, chapter 6. Fixture spacing 200mm.
5.5.3 Sampling method
Take the folded thread side as sampling side, two pieces of warp, weft, seam edge and seam bottom were taken on each bag, 300 mm long and 60 mm wide, and then corrected to 50 mm. If the last one is more than half of the root, it should be retained. The seams on both sides of the seam specimen should be lengthened appropriately.
5.5.4 The tensile load of the specimen was recorded and its arithmetic average value was taken.
5.5.5 In the test, if the sample is broken or slipped in the fixture, the sample should be replaced.
5.6 Heat Resistance
5.6.1 Two longitudinal and latitudinal specimens, 300 m long and 20 m wide, were taken from bagged soil.
5.6.2 Overlay its surface and apply a load of 9.8 N on it. Put them in the oven of 80C for 1 hour and remove them. Two pieces of weight A will be taken out.
Samples are separated to check whether there are abnormal conditions such as adhesion and melt marks on the surface.
5.7 Drop Resistance
The test method is carried out in accordance with G B/T 4857.5
5.7.1 Test environments were normal temperature and humidity.
5.7.2 The test site is flat cement ground.
5.7.3 Filling coefficient is o.80-0.85.
5.7.4 Test Quality and Material Selection
Type T A bags containing 20 kg polypropylene, polyethylene resin or similar density materials;
Type A bags containing 25 kg polypropylene, polyethylene resin or materials of similar density;
Type B bags containing 40 kg urea or materials of similar density;
Type C bags contain 50 kg of urea or similar densities of materials. G B/T 8946-1 998
5. 7. 5 Test Sequence
Article 1: Longitudinal – Horizontal – Lateral
Article 2: Horizontal-Lateral-Longitudinal
Article 3: Lateral – Longitudinal – Horizontal
5. 7. 6 Put the sample at the height of L. 2 m and drop freely. According to the order of 5. 7. 5, three drop tests are carried out to check whether the bag is broken or any leakage happens.
5.8 Hygienic Performance
According to G B/T 5009.60.
6 Testing Rules
6.1 groups of batches
Products of the same type and specification are in batches, each batch of which does not exceed 150,000 items.
6.2 sampling
6.2.1 Bags are judged to be qualified for appearance and deviation according to a normal sampling plan stipulated in G B/T 2828 (see chart 5), each
woven bag as a sample unit.
|
Batch QTY range |
Sample QTY |
QUALIFIED |
FAILED |
|
501-1200 |
32 |
5 |
6 |
|
1201-3200 |
50 |
7 |
8 |
|
3201-10000 |
80 |
10 |
11 |
|
10001-35000 |
125 |
14 |
15 |
|
35001-150000 |
200 |
21 |
22 |
chart 5 6.2.2 Tensile load was randomly sampled in 5 batches, of which 2 were spare and 3 were measured by 5.5.3 sampling.
6.2.3 Other inspection items shall be sampled randomly according to Chapter 5. The number of samples shall meet the test requirements of the required items.
6.3 Test Classification
6.3.1 Out-of-factory inspection items are tensile loads of 4.1, 4.2 and 4.3.
6.3.2 test
Type inspection items are all items in the technical requirements. Generally, they are inspected once a year. When one of the following situations occurs, type inspection should be carried out.
Type test:
(a) Trial identification of new or old products transferred to factories;
B) When the structure, material and process of the product are changed greatly after formal production, it may affect the performance of the product.
C) When production resumes after long-term shutdown of the product;
D) When there is a big difference between the ex-factory inspection results and the previous type inspection;
(e) Requirements for type inspection put forward by the State Quality Supervision Agency.
6.4 Decision Rules
6.4.1 Quality determination of sample units
The appearance and deviation of the bags are tested according to 4.1 A. 2. If all the items are qualified, the sample units are qualified.
6.4.2 Quality determination of qualified batches
6. 4. 2. 1 bags of appearance and deviation qualified judgement in accordance with the provisions of G B/T 2828, with the number of unqualified products per 100 units as the batch quality
Quantity, general inspection level is I, qualified quality level (A Q L) is 6.5. Specific provisions are shown in Table 50.
6.4.2.2 If there are unqualified items in the tensile load test, the unqualified items should be re-examined by double sampling in the original batch, and if the re-examination is completed.
If they are all qualified, the batch shall be qualified.
6.4-2.3 Heat Resistance Test
If the heat resistance test is not qualified, the type test is not qualified.
6.4.2.4 Drop test
If the drop test is not qualified, the type test is not qualified.
6.4-2.5 Hygienic Performance
If the hygienic performance is not qualified, the type test is not qualified.
7. Marking, Packaging, Transportation and Storage for Woven bags
7.1 Sign.
Product packaging should include the name of the manufacturer, product name, specifications, quantity, standard number, trademark, date of departure, etc. Special Requirements for Consultation between the Parties
Decision.
7.2 Packaging
7.2.1 Bags should be packed firmly and smoothly, suitable for transportation.
7.2.2 The number of packages per package shall be determined by consultation between the supplier and the buyer.
7.2.3 Each package shall have a product certificate.
7.3 transport
The bags should be lightly loaded and unloaded during transportation so as to avoid sunshine and rain and keep the package intact.
7.4 storage
Bags should be stored in a cool and clean room. The storage period should not exceed 18 months from the date of leaving the factory.
