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This standard specifies the product classification, requirements, test methods, inspection rules and marking, packaging, transportation and storage of stretch wrap films for transport packaging. This standard applies to stretch wrap films produced with polyolefin plastics as the main raw materials, used for non-direct contact with food, and used for transport packaging.

ICS55.040
Packaging Industry Standard of the People's Republic of China
BB/T0024—2018
Replaces BB/T0024—2004
Stretch wrap films for transport
Stretch wrap films for transport packaging2018-04-30 Issued
The Ministry of Industry and Information Technology of the People's Republic of China Issued
2018-09-01 Implementation
This standard was drafted in accordance with the rules given in GB/T1.1-2009. This standard replaces BB/T0024-2004 (Stretch wrap film for transport packaging). Compared with BB/T0024-2004, this standard has the following major technical content changes except for editorial modifications: BB/T0024-2018
Added that machine-use stretch film is divided into pre-stretched machine-use stretch film and resisted stretch machine-use stretch film, and hand-use stretch film is divided into front pre-stretched hand-use stretch film and ordinary hand-use stretch film. Product classification of wrapping film (see Chapter 4); deleted the three product classification methods of "number of adhesion layers, color" (see Chapter 4, Chapter 4 of the 2004 edition); added technical requirements for tensile strength, elongation at break and puncture resistance of pre-stretching machine wrapping film (see Table 3 of Chapter 5); modified the technical requirements for permanent deformation and elastic recovery of ordinary hand wrapping film (see Table 3 of Chapter 5, Table 3 of Chapter 5 of the 2004 edition); deleted the upper limit of the transverse tensile strength of hand wrapping film (see Table 3 of Chapter 5. Table 3 of Chapter 5 of the 2004 edition); deleted the technical requirements for light transmittance, haze and water vapor permeability (Table 3 of Chapter 5 of the 2004 edition); added factory inspection requirements for tensile strength, elongation at break and viscosity (See 7.1.1); revised Appendix A viscosity test device (see Appendix A, 2004 edition Appendix A); deleted Appendix D. Its content was edited into the main text (see 6.4.5, 2004 edition Appendix D). This standard was proposed by the China Packaging Federation. This standard was approved by the National Technical Committee for Packaging Standardization (SAC/TC49). Drafting units of this standard: Xiamen Jufu Plastic Products Co., Ltd., China Packaging Research and Testing Center, Bengbu Dacheng Packaging Technology Co., Ltd., Guangdong Shicheng Plastic Machinery Co., Ltd., Jinan Languang Electromechanical Technology Co., Ltd., Xiamen Baiqiang Technology Co., Ltd. The main drafters of this standard: Zhang Zhengjun, Chen Jianchao, Ren Baicheng, Zhang Chunhua, Zhao Xinwei , Jiang Yunzhong, Wu Yanqin. The previous versions of the standards replaced by this standard are: -BB/T0024—2004.
1 Scope
Stretch wrap film for transport packaging
BB/T0024—2018
This standard specifies the product classification, 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 following documents are indispensable for the application of this document. For all dated references, only the dated version applies to this document. For all undated references, the latest version (including all amendments) applies to this document. GB/T191 Pictorial marking for packaging, storage and transportation
GB/T1040.3 Determination of tensile properties of plastics Part 3: Test conditions for films and sheets GB/T2035: Plastic terms and definitions
Sampling inspection procedures by attributes Part 1: Sampling plan for batch inspection based on acceptance quality limit (AQI) GB/T 2828.1
GB/T2918
Standard environment for conditioning and testing of plastic specimens GB/T4122.1
GB/T6672
Terms and definitions
Packaging terms Part 1: Basics
Determination of thickness of plastic film and sheet
Mechanical measurement method
Terms and definitions established in GB/T2035 and GB/T4122.1 and the following terms and definitions apply to this document 3.1
cling
The adhesion between two layers of a stretch film in a stretched or unstretched state. 3.2
elasticrecovery
Elastic recovery
The ratio of the recovered size of a stretch film to the original size after it is stretched to a certain proportion and maintained in that state for a certain period of time, expressed as a percentage.
permanentdeformation
Permanent deformation
The ratio of the length of the stretch film after it is stretched to a certain proportion and released to the original length, expressed as a percentage. 3.4
F force value Fforcevalue
The maximum tensile force of the stretch film at a predetermined elongation. 3.5
stressretention
Tensile retention
The ratio of the tensile force of the stretch film to the F force value when it is stretched to a certain proportion for a certain period of time, expressed as a percentage. 1
BB/T0024—2018
Punch resistance
protrusionpunctureresistance is used to indicate the ability of the stretch film to resist needle puncture. It is expressed by the force value and extension displacement when the film ruptures during the puncture process. Product classification
According to the winding method of stretch wrap film, it can be divided into machine wrap film and hand wrap film; machine wrap film is divided into pre-stretched machine wrap film and resisted stretching machine wrap film; hand wrap film is divided into pre-stretched hand wrap film and ordinary hand wrap film; according to the production and processing method of wrap film, it can be divided into cast wrap film and blown wrap film; requirements
Size and specifications
The standard width of wrap film is 450mm.500mm, and the thickness is generally 0.010mm~0.050mm. The weight of each roll of film is no more than 25kg for machine wrap film and no more than 7kg for hand wrap film. The inner diameter and length of the roll core should meet the needs of the corresponding specifications. The specific specifications shall be determined by negotiation between the supply and demand parties according to needs. The allowable deviation shall comply with the requirements of Table 1 Table 1
Dimension and mass deviation
Width deviation
Thickness deviation
Core length deviation
Core inner diameter deviation
Film roll mass (net weight of film) deviation
Appearance shall comply with the requirements of Table 2.
Bubbles, perforations, cracks
Photo blocks, white marks, foreign matter
Technical requirements
The thickness of any measuring point is not allowed to exceed ±15% of the nominal thickness; the average measured thickness is not allowed to exceed ±10% of the nominal thickness0~3mm
The quality deviation of hand-held single-roll film is ±1% of the nominal quality; the quality deviation of machine-used single-roll film is ±2% of the nominal qualityAppearance requirements
First-class products
Not allowed
Not allowed
Not allowed
Not allowed
Qualified products
One is allowed
Not allowed
Not allowed
(pieces/m2)
0.3mm~0.6mm
Dispersion
[pieces/(10cm×10em)]
Flatness (except for pre-stretched film)
Mechanical properties
Technical requirements for mechanical properties are shown in Table 3.
Break force
Elongation at break
Permanent deformation
Elastic recovery
Tensile force retention
F force value
Punch resistance
Unstretched
Cast film
Euro plastic film
Cast film
Blown film
Cast film
Blown film
Cast film
Blown film
Break force
Elongation
Mass deviation per unit area
Table 2 (continued)
First-class products
Not allowed
Machine stretch film flatness
Degree ≤1mm
The surface of the film is basically flat Flat,
allow slight live folds,
film roll end surface is flat
Mechanical properties
BB/T0024—2018
Qualified products
Not allowed
The film surface is basically flat, slight live folds are allowed, and a small amount of film edge is allowed to exceed the end surface, but it shall not affect the use
Technical requirements
Pre-stretching
Resistant stretching
Pre-stretching
≥400
BB/T0024—2018
6 Test methods
Sample state adjustment and test standard environment Sample state adjustment and test standard environment shall be carried out in accordance with GB/T2918. Test environment conditions The temperature is 23℃±1℃, the relative humidity is 50%±5%, and the sample pretreatment time is more than 4h under standard environment conditions. 6.2 Dimensions and specifications
6.2.1 Width
Unfold the film and spread it on a flat, smooth and clean table. Measure 3 times at equal distances, round to 1mm and take the average value. 6.2.2 Thickness
Perform according to the provisions of GB/T6672. Cut a 100mm full-length sample along the length direction, place it for 30 minutes, measure 20 points, read the value accurately to 0.001mm, and take the arithmetic mean. 6.2.3 Inner diameter of the roll core
Measure the inner diameter of the roll core with a universal measuring tool, read the value accurately to 1mm, and take the arithmetic mean after measuring 3 points. 6.2.4 Length of the roll core
Measure the length of the roll core with a measuring tool, read the value accurately to 1mm. 6.2.5 Mass of the film roll
Weigh it with an electronic scale and round the calculated result to 0.1kg. 6.3 Appearance inspection
The appearance requirements for bubbles, perforations, cracks and flatness are visually inspected under natural light for a sample with an area of ​​1m. The size of the rigid blocks, white prints, foreign matter and crystal points is inspected with a 10x scale magnifying glass, calculated by the maximum length, and the dispersion is checked with a 10cm×10cm frame plate.
6.4 Mechanical properties
6.4.1 Breaking force and elongation at break
According to GB/T1040.3, type II specimens with a width of 15mm are used. The test samples should be cut after 1m of unwinding, and cut at approximately equal intervals along the length or width of the sample. The samples must not be contaminated or damaged, the sample surface must not be touched with bare hands, and the samples must not be marked. The inner and outer sides of each sample are separated and protected with general writing paper. The inner and outer sides and the longitudinal and transverse directions of the sample are marked on the separation paper. During the test, the distance between the clamps of the tensile testing machine is 50mm, the gauge length is 50mm, and the test speed is 250mm/min±25mm/min. There are one group of longitudinal and transverse samples, and each group has no less than 5 samples. The arithmetic mean is taken, accurate to 0.1N. 6.4.2 Viscosity
Test in accordance with the provisions of Appendix A.
6.4.3 Elastic recovery, permanent deformation, tensile retention and F force value are tested in accordance with the provisions of Appendix B.
6.4.4 Puncture resistance
Test in accordance with the provisions of Appendix C.
6.4.5 Unit area mass deviation
6.4.5.1 Test steps
BB/T0024—2018
Cut the sample from one of the rolls in the sample. The unwinding speed is appropriate, and the film cannot be stretched. After removing the outermost two layers of the film roll, take the sample length based on the width of the film roll: prepare 3 samples. When cutting the sample, do not touch the sample surface with your hands, and ensure that both the inner and outer sides of each sample are protected by separator paper. First, open the film roll and lay it flat on a flat, smooth, clean table top covered with protective paper: cut a certain length in the vertical direction of the width to ensure that the mass of the obtained sample is greater than 1g; weigh the mass of the sample to an accuracy of 0.001g. 6.4.5.2
Test results
Take the arithmetic mean of the three samples tested, and round the numbers to integers. a
The unit area mass of the sample is calculated according to formula (1): u=m/s
Where:
The unit area mass of a sample, in grams/square meter (g/m); u
mThe mass of the sample, in grams (g);
The area of ​​the sample, in square meters (m). b) If judgment is made, calculate the deviation of each sample based on the average value. 7 Inspection rules
Inspection classification
The factory inspection items are appearance, specification size, tensile strength, elongation at break, and viscosity. 7.1.2
Type inspection is all the items specified in Chapter 5 of this standard. Type inspection should be carried out when one of the following situations occurs: identification of new products put into production;
When changes in structure, process, and materials may affect product performance; During normal production, an inspection is carried out once a year; When the product is resumed after a long period of suspension
7.2 Sampling
Inspection batch
.. (1)
One inspection batch is a woven film produced with the same raw materials, the same process, and the same structure. The maximum batch shall not exceed 1,000 rolls. 7.2.2 Sampling plan
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.
Type inspection
Perform all items 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 inspection specified in Chapter 5. 7.3
Judgment rules
Judgment of qualified items
The inspection results of size, specification and appearance shall be judged individually 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 as qualified.
The mechanical properties test results 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 is judged to be qualified.
Qualified Critical Assessment
Factory Inspection
The qualified critical assessment of factory inspection is shown in Table 4.
151~500
501-1000
Type Inspection
Sample Size
Number of Qualified Determination
Unit is roll
Number of Unqualified Determination
The 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 judged to be qualified: If there are unqualified items in size, specification and appearance, and all mechanical properties are qualified, double the samples shall be drawn for size, specification and appearance inspection. If all the samples are qualified, the batch of products shall be judged to be qualified. If there are unqualified items, the batch of type inspection shall be judged to be unqualified. Marking, packaging, transportation and storage
8.1 Marking
Storage and transportation graphic markings shall comply with the provisions of GB/T191. The film roll or packaging shall be labeled with the product name, product category, production date, implementation standard, specifications, and manufacturer. Each batch of products shall be accompanied by a product certificate and marked with the batch number and inspector's seal. 8.2 Packaging
The outer packaging shall use corrugated paper boxes or flat pallets, etc. 8.3 Transportation
During transportation, the product should be dust-proof, moisture-proof, and sun-proof. During loading and unloading, it should be lifted and placed gently and not subjected to heavy pressure. And it should be placed neatly to prevent mechanical damage.
8.4 Purchase and 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 the heat source. The storage period is 1 year from the date of production. 6
A.1 Test device
Device used for viscosity test.
Appendix A
(Normative Appendix)
Viscosity test method
BB/T0024—2018
This device consists of a tripod and an L-shaped frame. During the test, the tripod is fixed on the L-shaped frame, and the film is pulled out from the tripod through the L-shaped frame roller and clamped by the tensile machine fixture. The principle of the test device is shown in Figure A.1. The unit is millimeter
Explanation:
Chassis;bzxz.net
Test inclined plane;
Pulley;
Pulley bracket;
Specimen.
Figure A.1 Schematic diagram of viscosity test device
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 to indicate different elongation rates of the specimen. The distances between the scale lines and 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%. 7
BB/T0024—2018
A.2 Preparation of test samples
Schematic diagram of test inclined plane
Sampling begins after the test sample is unrolled 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 specimen, do not touch the surface of the specimen with your hands. Add separator paper in the paper-film-paper manner to 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.
Start the test within 30 minutes after the specimen is prepared. A.3 Test steps
Take a group of specimens, lay and fix the 500mm×125mm specimen on the test inclined plane with the longitudinal direction consistent with the length of the inclined plane according to Figure A.3, with the inner side facing downward, find the corresponding scale mark on the inclined plane according to the required stretching ratio, and mark the scale on the specimen. Built-in specimen clamp
Figure A3 Schematic diagram of specimen fixing
There are two built-in specimen clamps on each of the two right-angled edges of the tripod to fix the specimen. Use the guide rod to evenly stretch the specimen so that the mark reaches the top of the inclined plane and lock the specimen.
Cut a 180mm×25mm specimen and lay it flat on the fixed lower specimen, with the longitudinal direction consistent with the inclined plane and one end aligned with the top of the inclined plane, with the inner side facing downward, and use a soft brush to make the two specimens bonded and smooth: curl the upper specimen from the upper end of the inclined plane to the center line of the inclined plane and pass it through the roller clamp to the tensile machine.
Pull the fixture at a speed of 125mm/min±12.5mm/min until the two samples are separated. Record the maximum force value during the separation process.
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