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Packaging Industry Standard of the People's Republic of China
BB/T0024—2004
Stretch wrap films for transport packaging
Stretch wrap films for transport packaging2004-01-09Published
National Development and Reform Commission of the People's Republic of ChinaImplemented on 2004-06-01
Packaging Industry Standard of the People's Republic of China
Stretch wrap films for transport packaging
BB/T0024—2004
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BB/T0024—2004
This standard adopts the American standard ASTMD1649 "Guide to the Selection and Use of Stretch Wrap Film". However, the scope of application of this standard is different from that of ASTMD4649. Therefore, some requirements and inspection items were removed during the standard formulation process, including: friction coefficient, gloss, surface tension, electrical insulation properties, flammability, etc. Appendix A, Appendix B, Appendix C, and Appendix D of this standard are all normative appendices. The standard is proposed by the China Packaging Technology Association. This standard is under the jurisdiction of the National Packaging Standardization Technical Committee. The main drafting unit of this standard: China Packaging Research and Testing Center. Participating drafting units of this standard: Fuzhou Jiatong First Plastic Co., Ltd., Nan Ya Plastic Industry (Chongqing) Co., Ltd., Shanghai Dazhi Enterprise Group, Huayi New Plastic Industry (Suzhou) Co., Ltd., Jiangyin Longqi Packaging Materials Co., Ltd. The main drafters of this standard: Li Hua, Shao You, Yang Wei, Li Wenxiang, Li Zhijian, Huang Jingliang, Wang Chuanbin, Lin Yuanzhi, Guo Jian, Wang Lirui, Xie Mingsheng, Tu Nongchang, Liu Ming.
1 Scope
Stretch wrap film for transport packaging
BB/T0024—2004
This standard specifies the product classification, technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of stretch wrap film for transport packaging (hereinafter referred to as wrap film). This standard applies to stretch wrap film for transport packaging produced with polyolefin plastic as the main raw material and used for non-direct contact with food. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, the parties to the agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all undated references, the latest versions shall apply to this standard. GB/T191 Pictorial marking for packaging, storage and transportation
GB/T1037—1988 Test method for water vapor permeability of plastic film and sheet GB/T2035 Plastic terms and definitions
GB/T2410--1980 Test method for light transmittance and haze of transparent plastics GB/T2828.1 Sampling inspection procedure by attributes Part 1: Insertion plan for batch inspection indexed by acceptance quality limit (AQL) GB/T2918 Standard environment for conditioning and testing of plastic specimens GB/T4122 Packaging terms
GB/T6672—2001 Determination of thickness of plastic film and sheeting - Mechanical measurement method GB/T13022—1991 Test method for tensile properties of plastic film 3 Terms and definitions
The terms and definitions established in GB/T2035 and GB/T4122 and the following terms and definitions apply to this standard. 3.1
The adhesion between two layers of shrink film in stretched or unstretched state. 3.2
Elastic recovery
The ratio of the recovered size of the stretch film to the original size after being stretched to a certain proportion and kept in this state for a certain period of time, expressed as a percentage.
Permanent deformation
The ratio of the length of the stretch film to the original length after being stretched to a certain proportion, expressed as a percentage. 3.4
F force value
The maximum tensile force of the stretch film at a predetermined elongation. 3.5bZxz.net
Tensile retention
The ratio of the tensile force of the stretch film to the F force value after being stretched to a certain proportion and kept in this state for a certain period of time is the tensile retention, expressed as a percentage.
BB/T0024—2004
Punch resistance
Used to indicate the ability of the stretch film to resist needle puncture. It is expressed by the force value when the film breaks during the puncture process and the displacement when passing through. Product classification
According to the winding method of the stretch wrap film, it can be divided into hand wrap film and machine wrap film; the production and processing method of the wrap film can be divided into cast wrap film and blown wrap film; - the way of viscosity increase can be divided into single-sided adhesive wrap film, double-sided adhesive wrap film, migratory viscosity increase wrap film and non-migratory viscosity increase wrap film; one layer distinction can be divided into single-layer wrap film and multi-layer co-extruded wrap film; one color distinction can be divided into transparent wrap film, color wrap film and opaque wrap film. 5 Requirements
5.1 Size and specifications
The standard width of the wrap film is 500mm, and the thickness generally ranges from 0.015mm to 0.050mm. The mass of each roll of film is no more than 25kg for machine film and no more than 5kg for hand film. The inner diameter and length of the roll core should meet the needs of the corresponding specifications. The specific specifications are determined by the supply and demand parties according to needs. The allowable deviation should comply with the provisions of Table 1. Table 1 Dimension and quality deviation
Width deviation
Thickness deviation
Core length deviation
Core inner diameter deviation
Mould roll quality deviation
5.2 Appearance
Technical requirements
The thickness of any measuring point shall not exceed the nominal thickness by ±15%; the average measured thickness shall not exceed the nominal thickness by ±10%±3mm
The quality deviation of a single roll of film shall not exceed the nominal quality by ±5%; the average quality of 5 rolls of film shall not exceed the nominal quality by ±2%. The appearance shall meet the requirements of Table 2.
Bubbles, perforations, ruptures
Color limit/(pieces/m)
0.3mm~0.6mm
Dispersion/[pieces/(10cm×10cm）]
Smoothness
5.3 Physical and mechanical properties
Physical and mechanical properties technical requirements are shown in Table 3.
Table 2 Appearance requirements
First-class products
Not allowed
Not allowed
Not allowed
Not allowed
The film surface is basically flat, a slight live skirt is allowed, and the end surface of the film roll is flat.
Not allowed
Qualified products
1 allowed
Not allowed
Not allowed
The film surface is basically flat, slight live folds are allowed, and a small amount of film edge is allowed to extend beyond the end surface, but it must not affect the use.
Break force/N
Elongation at break/(%)
Viscosity/N
Cast film
Blown film
Punch resistance
Unstretched
Table 3 Physical and mechanical properties
≥350
Stretched 100%
Permanent deformation/%)
Elastic recovery/(%)
Tensile force retention/(%)
F force value/N
Permanent deformation/(%)||t t||Elastic recovery/(%)
Tensile retention/(%)
F force/N
Rupture force/N
Elongation/mm
Weight deviation per unit area/(%)
Light transmittance/(%)
Haze/(%)
Water vapor transmission/(g/m2.24h)
Technical requirements
Note 1: The light transmittance and haze tests are limited to products with a film thickness of less than 0.030mm and transparent and colorless. Note 2: The technical indicators of permanent deformation, elastic recovery, tensile retention and F force value tests refer to 50% for manual use and 100% for machine use. Test method
6.1. Sample state adjustment and standard test environment BB/T0024—2004
≥400
The sample state adjustment and standard test environment shall be carried out in accordance with GB/T2918. The sample pretreatment time under standard environment shall be more than 4h. The test environment temperature shall be 23℃±1℃ and the relative humidity shall be 50%±5%. 6.2. Size and specification
6.2.1 Width
Unfold the film and spread it on a flat, smooth and clean table. Measure 10 times at equal distances, round to 1mm and take the average value. 6.2.2 Thickness
Perform in accordance with GB/T6672. Cut a 100mm full-length sample along the length direction, place it for 30min, measure 20 points, read the value accurately to 0.001mm, and take the arithmetic mean. 6.2.3 Inner diameter of roll core
Use a universal measuring tool to measure the inner diameter of the roll core, and read the value accurately to 1mm. Take the arithmetic mean after measuring 3 points. 3
BB/T0024—2004
6.2.4 Length of roll core
Use a measuring tool to measure the length of the roll core, and read the value accurately to 1mm. 6.2.5 Film roll quality plate
Weigh with a platform scale, and the calculated result is rounded to 0.1kg. 6.3 Appearance inspection
The requirements for bubbles, perforations, ruptures and flatness in the appearance requirements are visually inspected under natural light for samples with an area of 1m. The size of impurities, "fish eyes" and "blocks" is inspected with a 10x scale magnifying glass, calculated based on the maximum length, and the dispersion is checked with a 10cm×10cm frame plate.
6.4 Physical and mechanical properties
6.4.1 Breaking force and elongation at break
According to GB/T13022-1991, IV type test specimens with a width of 15mm are used. The test specimens should be cut after 1m of unwinding, and cut evenly at approximately equal intervals along the length or width of the sample. It is not allowed to touch the surface of the specimen with hands, and it is not allowed to mark the specimen. The inner and outer sides of each specimen are separated and protected with general writing paper. The inner and outer surfaces and the longitudinal and transverse directions of the specimen are marked on the separation paper. During the test, the jaw distance of the tensile testing machine is 50mm, the gauge length is 50mm, and the test speed is 250mm/min±25mm/min. The longitudinal and transverse directions form a group, and each group of specimens is not less than 5. The average value is taken and the accuracy is 0.1N. 6.4.2 Viscosity
Test according to the provisions of Appendix A.
6.4.3 Elastic recovery, permanent deformation and tensile retention are tested according to the provisions of Appendix B.
6.4.4Punch resistance
Test according to the provisions of Appendix C.
6.4.5Weight per unit area
Test according to the provisions of Appendix D.
6.4.6Light transmittance and haze
Test according to the provisions of GB/T2410.
The test sample should be cut after unwinding for 1m, and cut evenly at approximately equal intervals along the length or width of the sample. It is not allowed to touch the surface of the sample with your hands, and it is not allowed to mark the sample. The inner and outer sides of each sample are separated and protected by ordinary writing paper. And mark the inner and outer sides of the sample on the separation paper. During the test, proceed from the outside to the inside, test 3 test samples, and take the arithmetic average. The light transmittance is accurate to the integer, and the haze is accurate to one decimal place. 6.4.7Water vapor transmission disk
Test according to the provisions of GB/T1037-1988. The test conditions are 23℃±0.6℃ and 90%±2% relative humidity. 7 Inspection rules
7.1 Inspection classification
7.1.1 Factory inspection: Inspect the product specifications, dimensions and appearance according to the requirements of 5.1 and 5.2. 7.1.2 Type inspection: Type inspection should be carried out in any of the following cases: a) Appraisal of new product production;
b) When changes in structure, process or materials may affect product performance; c) During normal production, inspection should be carried out every six months; d) When the product is resumed after a long period of suspension; e) When the quality supervision agency or customer requests type inspection. Type inspection shall be carried out in accordance with the test items specified in Chapter 5 of this standard. 4
7.2 Sampling
7.2.1 Inspection batch
BB/T0024—2004
Stretch films produced with the same raw materials, the same process and the same structure are considered as one inspection batch, and the maximum batch shall not exceed 1000 rolls. 7.2.2 Sampling plan
7.2.2.1 Factory inspection
Perform according to GB/T2828.1, adopt special inspection level S-3, qualified quality level AQL=4.0. Normal inspection one sampling plan.
7.2.2.2 Type inspection
Perform all items of inspection according to the requirements of Chapter 5. Randomly select 5 rolls from each batch of products for film roll quality inspection, and then randomly select 1 roll from them for other items specified in Chapter 5. If one item fails, the type inspection is judged to be unqualified. 7.3 Judgment rules
7.3.1 Judgment of qualified items
The inspection results of size, specification and appearance shall be individually judged according to 5.1 and 5.2. If they meet the requirements of the standard, the size, specification and appearance of the sample shall be judged to be qualified.
The inspection results of physical and mechanical properties shall be individually judged according to the provisions of Table 3 in 5.3. If the individual items meet the corresponding provisions in Table 3, the sample shall be judged to be qualified.
7.3.2 Critical evaluation of qualified items
7.3.2.1 Factory inspection
The critical evaluation of factory inspection is shown in Table 4.
Batch/roll
≤150
151~500
501~1000
7.3.2.2 Type inspection
Sample quantity/roll
Number of qualified judgments/roll
Number of unqualified judgments/roll
Samples shall be inspected according to 5.1, 5.2 and 5.3. If all of them are qualified, the batch of products shall be deemed qualified; if there are unqualified items in size, specification and appearance, but all of the physical and mechanical properties are qualified, double the number of samples shall be taken for size, specification and appearance inspection. If all of the samples are qualified, the batch of products shall be deemed qualified. If there are unqualified items, the batch of type inspection shall be deemed unqualified. 8 Marking, transportation and storage
8.1 Marking
The film roll or package shall be labeled with the product name, product category, production date, specification and manufacturer. Each batch of products shall be accompanied by a product certificate and marked with the batch number, inspection agency, and inspector's seal. Storage and transportation graphic signs shall comply with the provisions of GB/T191. 8.2 Packaging
Outer packaging shall use corrugated cardboard boxes or flat pallets. 8.3 Transportation
During transportation, the product should be protected from dust, moisture, and sunlight. During loading and unloading, it should be lifted and placed gently without heavy pressure. And placed neatly to prevent mechanical damage.
8.4 Storage
The product should be stored in a clean, cool, and dry warehouse, and should not come into contact with corrosive chemicals and other harmful substances. It should be at least 1m away from heat sources. The shelf life is one year.
BB/T0024—2004
A.1 Test device
Appendix A
(Normative appendix)
Viscosity test method
The device used for the viscosity test shall be customized in accordance with this standard. The principle of the test device is shown in Figure A.1. 6
A chassis;
Test slope:
Fixed device;
A pressure roller;
Fixed knob:
Pulley;
A pulley bracket:
Connecting parts.
Figure A.1 Schematic diagram of the viscosity test device
Three marking lines on the surface
Figure A.2 Schematic diagram of the test inclined plane
Unit: mm
a=20°
BB/T0024—2004
There should be three marking lines on the test inclined plane, as shown in Figure A.2, indicating the center line of the inclined plane and the 25mm width position in the middle of the inclined plane.
There should also be scale lines on the test inclined plane indicating different elongation rates of the specimen. The distances of the scale lines from the top edge of the inclined plane are 0mm, 50mm, 75mm and 100mm, respectively, and the corresponding specimen elongation rates are: unstretched, stretched 50%, stretched 100% and stretched 200%. A.2 Preparation of test samples
The viscosity test should start one week after the machine is off the production line. Sampling starts after the test sample is unwound for 1m. The specimens are grouped into two types: 500mm×125mm (vertical×horizontal) and 180mm×25mm (vertical×horizontal). The number of specimens under each tensile condition should be no less than 3 groups. When cutting the specimens, do not touch the surface of the specimens with your hands. Add separator paper in the form of paper-film-paper to ensure that both the inside and outside of each specimen are protected by separator paper. Mark the inside and outside of the specimen on the separator paper. Start the test within 30 minutes after the specimen is prepared. A.3 Test steps
Take a group of samples, lay and fix the 500mm×125mm sample with the longitudinal direction consistent with the length of the inclined plane according to Figure A.3, with the inner side facing downwards, find the corresponding scale mark on the inclined plane according to the required stretching ratio, and mark the sample according to the scale. Figure A.3 Schematic diagram of sample fixing
Use the guide rod to evenly stretch the sample so that the mark reaches the top end of the inclined plane and lock the sample. Lay the 180mm×25mm sample with the longitudinal direction consistent with the inclined plane and one end aligned with the top of the inclined plane on the fixed sample with the inner side facing downwards, and use a special brush to make the two samples bonded and flat; curl the upper sample from the lower end of the inclined plane to the center line of the inclined plane, and clamp the curled part with a clamp.
Pull the clamp at a speed of 125mm/min±12.5mm/min until the two samples separate, and record the maximum force value during the separation process, with the reading accurate to 0.1N.
A.4 Test result processing
Under the same stretch ratio, the number of tests shall be no less than 3 groups, and the arithmetic mean shall be taken, retaining 0.1N. BB/T0024—2004
B.1 Test sample preparation
Appendix B
(Normative Appendix)
Test method for longitudinal elastic recovery, permanent deformation and tensile retention of stretch wrap film Take 5 specimens on the test sample, the specimen width is 25mm (the transverse direction of the test sample is the specimen width), and the specimen length is 150mm.
When cutting the specimen, do not touch the surface of the specimen by hand, add separator paper in the form of paper-film-paper, and ensure that both the inner and outer sides of each specimen are protected by separator paper. And mark the inner and outer sides of the specimen on the separator paper. The edge of the specimen is smooth and without gaps, and can be checked with a low-power magnifying glass, and the specimen with defective edges is discarded. B.2 Test steps
B.2.1 Measure the thickness of 5 points in the longitudinal direction of each sample and take the arithmetic mean. The thickness is accurate to 0.001mmB.2.2 Adjust the jaw distance of the tensile tester to 125mm, so that the 5 samples are placed in the two clamps of the tester respectively, and the longitudinal axis of the sample coincides with the center line of the upper and lower clamps.
B.2.3 The test speed is 125mm/min±12.5mm/min. B.2.4 Stretch the sample to the predetermined elongation (4 types: 50%, 100%, 150%, and 200%) and wait for 60s±2s. B.2.5 The tester relaxes the sample to the original position at the original speed and waits for 180s±2s. B.2.6 The tester re-stretches the sample to the predetermined elongation position. The plotter of the testing machine records the test curve (as shown in Figure B.1): c
Figure B.1 Test plotted curve
B.2.7 Calculation method:
As shown in Figure B.1, calculate according to formula (B.1), formula (B.2) and formula (B.3): Permanent deformation (%) =
Elastic recovery (%)
Tensile retention (%)
Where:
AD—permanent deformation, in millimeters (mm); DE—elastic recovery, in millimeters (mm); AE—total elongation, in millimeters (mm); 8
energy×100
（1）
.（2）
·（3）
GE—tensile retention, in Newtons (N): BE—maximum tensile force at a given elongation, in Newtons (N). B.3 Test result processing
BB/T0024—2004
B.3.1 Take the average value of the results of 5 samples, round the F force value to 0.1N, and round the permanent deformation, elastic recovery disk, and tensile force retention values to integers.
B.3.2 The predetermined elongation can be selected from 50%, 100%, 150%, and 200%. This test is done for 50% for hand-wound film and 100% for machine-wound film. Other items can be negotiated according to user requirements. In addition, only one of elastic recovery and permanent deformation can be selected when judging.
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