This standard applies to fresh coagulated natural rubber latex, which is made into a crepe film after careful and consistent control of the entire production process. The thickness of the crepe must be approximately the same as the thickness of the sample. This standard does not apply to films made entirely or partially from latex. GB 8090-1987 Natural raw rubber white crepe film and light-colored crepe film GB8090-1987 Standard download decompression password: www.bzxz.net

1 Scope of application
National Standard of the People's Republic of China
Raw natural rubber-
White crepes and pale crepes
UDC 678. 4. 032
GB8090—87
1.1 This standard applies to fresh clotted natural rubber latex, which is a surface-roughened crepe made by careful and consistent control of the entire production process. The thickness of the crepe must be approximately the same as that of the sample. 1.2 This standard does not apply to crepes made wholly or partly from latex. 2 Technical requirements
2.1 Special Grade One Thin White Crepe
The goods delivered must be extremely white and uniform, dry and solid rubber. Discoloration, sour odor, dust, crumbs, grit or other foreign matter, oil or other stains, oxidation or overheating caused by any reason are not allowed.
2.2 Thin White Film
The goods delivered must be white, dry, solid rubber. Very slight differences in color are allowed. No discoloration, sour smell, dust, shavings, grit or other foreign matter, oil or other stains, signs of oxidation or overheating caused by any reason are allowed.
2.3 Special Thin Light Color Film
The goods delivered must be very light color and uniform, dry, solid rubber. No discoloration, sour smell, dust, shavings, grit or other foreign matter, oil or other stains, signs of oxidation or overheating caused by any reason are allowed.
2.4 Thin Light Color Film
The goods delivered must be light color, dry, solid rubber. Very slight differences in color are allowed. Discoloration, sour odor, dust, shavings, grit or other foreign matter, oil or other stains, signs of oxidation or overheating due to any cause are not permitted.
2.5 Grade 2 Thin Light Color Film
The goods must be dry and solid rubber. The color is slightly darker than Grade 2 Thin Light Color Film. Slight differences in color depth are allowed.
Rubber with spots and streaks to the extent shown in the sample is allowed. However, the number of such bales in the rubber bales inspected shall not exceed 10% of the number of rubber bales inspected.
Except as permitted above, discoloration, dust, shavings, grit or other foreign matter, oil or other stains, signs of oxidation or overheating due to any cause are not permitted.
2.6 Grade 3 Thin Light Color Film
The goods must be light yellow, dry and solid rubber. Differences in color depth are allowed. Rubber with spots and streaks to the extent shown in the sample is allowed. However, among the rubber bales inspected, the number of such rubber bales shall not exceed 20% of the number of rubber bales inspected.
GB 8090—87
Except for the above-mentioned permissible ones, discoloration, dust, crumbs, grit or other foreign matter, oil or other stains, oxidation or overheating caused by any reason are not allowed.
3 Inspection rules
3.1 Sampling method
After the delivered goods are stacked according to the grade marked on the product, random sampling is carried out at 5% of the total number of bales in each batch. The better or worse rubber bales shall not be deliberately selected. The specific method is to take 20 bales as a unit and select 1 bale from each unit. Once the sampling personnel have decided on the number of rubber bales to be drawn, the rubber bales of that number shall be drawn in order for each unit. One bale shall be drawn even if the number of bales in each batch is less than 20. The drawn rubber bales shall be placed on the ground covered with plastic sheeting or canvas, the rubber bales shall be opened, and 8 sheets shall be randomly drawn from each bale and placed on the original rubber bales for inspection.
3.2 Inspection method
Whether the quality of the delivered goods is consistent with the grade marked on the product can only be determined through visual inspection. During the inspection, the appearance of the single film in the physical standard sample book and the single film peeled from the inside of the rubber bale shall be compared with each other in combination with the textual provisions of the technical requirements. If the rubber bale to be inspected cannot be peeled from a single film, in the absence of discoloration, the darker color of the compressed rubber shall be considered. During the inspection, a bright light source shall be provided to see through the defects inside the film. The inspector shall select one film with medium appearance quality from the 8 sheets randomly drawn from each bale, representing the average quality of the 8 sheets as the rated film. Among the eight films with the average quality, one film with a lower quality by one grade is allowed, but if there is a film with a lower quality by two grades, the film shall be taken as the rated film.
Then, the inspectors shall weigh the rated films one by one and assess the grade. The downgraded rated films shall be properly preserved, and the inspection results and instructions shall be attached for re-inspection by the relevant parties. 3.3 Assessment of inspection results
The number of packages in the batch that meet each grade shall be calculated as the inspection result, with each rated film representing 20 packages. 4 Packaging, marking, storage and transportation
4.1 Packaging
The rubber bag shall be double-layered with ethylene film bags and polypropylene woven bags, with a net weight of 50kg per bag. The length of the rubber bag is 60±2cm, the width is 40±2cm, and the height is 30±2cm.
It is allowed to sprinkle a small amount of fine talcum powder around the upper and lower sides of the packing box so that the film can be smoothly separated from the packing box after being pressed. 4.2 Marking
The largest side of each rubber bag shall be marked with: product name, grade, net weight, manufacturer code, and production date. The size of the logo font shall be uniformly stipulated by the rubber production management department. 4.3 Storage and transportation
4.3.1 Rubber bags shall be stacked according to type and grade, and stored on wooden boards 30 cm above the ground and 50 cm above the wall. The stacking height is 4 to 6 rubber bags, and the stacking length is unlimited. There shall be passages between each pile of rubber bags for easy removal and transportation. 4.3.2 The warehouse for stacking rubber bags shall be well ventilated, dry, and rainproof. The temperature in the warehouse shall not exceed 35°C, and the humidity shall be kept as low as possible.
4.3.3 The warehouse shall be clean, and the rubber bags shall not be exposed to direct sunlight. 4.3.4 Rubber bags shall not come into contact with salts or oxides of copper and manganese, and shall not be stored with oils and flammable items. 4.3.5 During transportation, the rubber must be transported in a clean carriage and covered with tarpaulin to prevent direct sunlight or rain from causing the rubber to mold and deteriorate. 73
A.1 Skim
GB 8090-87
Appendix A
Terms
(Supplement)
When latex is concentrated by centrifuge, a concentrated latex with a dry rubber content of about 60% is obtained. The other part of the liquid containing about 5% dry rubber is called skim. A.2 Dry rubber
Rubber that does not show any signs of moisture based on appearance identification (see bleached rubber and virgin rubber). A.3 Bleached rubber
Rubber that has absorbed too much water due to moisture.
A.4 Virgin rubber
Rubber that still retains a large amount of original moisture and has a grayish white appearance. A.5 Weak rubber
Also known as brittle rubber. Rubber that is easily torn or broken when the rubber is stretched sharply. A.6 Strong rubber
Strong rubber
Rubber that is resistant to deformation and stretching. Firm rubber
Firm rubber
Based on appearance, it is very different from the state of weak rubber and is uniformly strong and firm. A.8 Discoloration
Discoloration
Refers to the phenomenon of color spots. The main reason is that there is undried rubber in the rubber bag, which causes biodegradation. This phenomenon may be accompanied by the smell of mold, overheated spots or decomposition of odorous substances. A.9 Sour and foul odors Odors caused by the corruption of rubber.
A.10 Speck
Debris of bark and other foreign organic matter in rubber. A.11 Sand
Small loose particles of quartz components that exist in rubber to a greater or lesser extent. A.12 Foreign matterwww.bzxz.net
Any substance in natural rubber except rubber hydrocarbons and natural substances inherent in latex is called foreign matter. 74
Oxidized rubber
GB 8090-87
Rubber that is damaged or degraded due to the combination of rubber hydrocarbons, whey substances and oxygen in rubber. A. 14
Overheated rubber
Heated rubber
Rubber with spots or streaks that become soft and sticky. A.15
Mottled rubber
Mottled rubber
Natural rubber with darker spots, stains or streaks and spots formed by fungi. Appendix B: Standard samples of white crepe and light-colored crepe (supplement) B.1 Standard samples of white crepe and light-colored crepe include: the physical standard sample of first-grade thin white crepe (No.1X ThinWhite Crepe); the physical standard sample of first-grade thin white crepe (No.1 ThinWhite Crepe); the physical standard sample of first-grade thin light-colored crepe (No.1 ThinPaleCrepe); the physical standard sample of first-grade thin light-colored crepe (No.1ThinPaleCrepe), the physical standard sample of second-grade thin light-colored crepe (No.2 ThinPaleCrepe); the physical standard sample of third-grade thin light-colored crepe (No.3ThinPaleCrepe). B.2 The "Copy International Sample" is used as the parent sample of the physical standard sample of this standard. Additional remarks:
This standard is proposed by the Ministry of Agriculture, Animal Husbandry and Fisheries of the People's Republic of China and is under the jurisdiction of the Natural Rubber Standardization Technical Committee of the National Rubber Standardization Technical Committee.
This standard was drafted by the Tropical Crop Products Inspection Institute of the Ministry of Agriculture, Animal Husbandry and Fisheries. The main drafter of this standard is Huang Kefen.
This standard is equivalent to the "International Standard for Natural Rubber Grades, Quality and Packaging (Green Book)" 1979).
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