The analysis and treatment of quality defects of hot filling PET bottle
Abstract: this paper analyzes the forming process, quality control point, PET bottle quality defect analysis and taking measures from hot filling PET bottles. The analysis and analysis of the quality defect of PET bottle hot filling beverage were analyzed and discussed.
Key words: PET; Hot filling; drinks
1. Molding process of hot filling PET bottle
The process of hot filling PET bottles is developed based on the technology of cold bottling PET bottles. Because of the special requirements of hot filling PET bottles, the process of one-step and two-step process is no longer consistent. The bottle mouth of hot filling PET bottle has special requirement, one step is required to deal with the bottle mouth when it is formed. The two-step method only requires processing before reheating. In general, if the bottle with PC material, usable one-step and two-step molding, molding molding bottle first before use insert molding method or total injection method is used to produce the bottle no longer shrinking bottle preform; If the bottle and the bottle with PET resin, can only use two-step process (two step here and cold filling do not match the two-step define the content of PET bottle, just continue, because here the so-called two-step production of hot filling bottle PET bottle crystallization finalize the design was done on separate machines). Hot filling one-step production process of PET bottle are as follows: PET resin - drying - co-injection or insert to the pipe forming tube billet temperature regulation to stretch blow molding, high temperature heat styling to cooling out and finalize the design product, finished product. For the two-step method, if the pipe is generated by the above step method, the process is basically consistent with the one-step process. But if use the same bottle bottle PET resin, the technological process is: PET resin and drying to crystal bottle, tube billet reheat to stretch blow molding, high temperature heat styling to cooling out and finalize the design product, finished product. This is also the way to do hot filling PET bottles.
II. Quality control points
(1) the acceptance raw materials of raw materials and packaging materials shall be sent to the relevant inspection departments for testing according to the requirements of each raw material, and shall not be used for unqualified materials; The appearance and hygiene standards of packaging materials also need to be used according to the relevant standards of the company.
(2) water quality requirements
All the deployment of using water, raw materials of anti-bacterial and bottling the linkage with clean water, the production of all the various disinfection to use clean water, clean water in the bottles are R.O treatment after the water must be used; The raw material dispensing unit USES water in the clean water and cooling department, and the water quality can be used in the linkage of the sterilizing equipment and the bottling device. However, it is important to note that the used tap water needs to meet the relevant water quality standards, the standard in the sanitary standards of living drinking water.
(3) deployment
1. Filtration.
All kinds of materials have been prepared and put into the device. Feeding should view the screen is in good condition before, otherwise the screen do not use need to replace screen, screen mesh at the same time before being used to soak the son ah 9 0 ℃ of pure water in a certain time; The syrup needs to pass through a half - mu filter bag.
2. Add essence and pigment.
A good amount of essence and pigment is diluted with water of about 10 times. Then the container can be diluted and then added to the container. After adding, the mixer will be opened and stirred up 15 m I n.
3. Control of semi-finished products.
The semi-finished products can only be further processed after they meet the standard, otherwise the semi-finished products will be processed until the standard is reached.
4. Schedule of ingredients.
The progress of the batching standard is based on the standard of feeding liquid. The time of the static setting of the liquid is not greater than 6 h, and the time calculation of the static setting shall be based on the timing of the deployment of the production record. The device is clean, the sterilization process is discarded after a long time, and the whole tank can be cleaned and sterilized and then put into production.
(4) homogeneity
Material liquid through homogeneous process can make each other mutual miscibility of 2 kinds of liquid closer integration, make one of the components into a small ball drops and then spread among the other components, to obtain the mixture liquid of particle is small and uniform, prevent pulp separation and precipitation. The juice and milk need homogenizing after normal liquid; All kinds of material with the finished product after the material liquid, in front of the UHT sterilization and need to be homogeneous, pressure of 2 0 M P a, for the first time operation again increased to 2 5 MPa, the temperature is 65 ~ 70 ℃.
(5) U H T sterilization
1. The sterilization process of different beverages is different in temperature and time.
Fruit juice: sterilization temperature at 105 ℃, sterilization time is about 15 s. Such as fruit juice, the sterilization temperature at 105 ℃, sterilization time is about 15 s. Such as ice tea: the sterilization temperature at 115 ℃, sterilization time is about 15 s. Such as green tea: the sterilization temperature at 136 ℃, sterilization time is approximately 30 s; Such as nutrient express: sterilization temperature at 125 ℃, sterilization time is about 15.
2. System disinfection.
Before being sent to full automatic sterilization device, the UHT sterilization device should be tested and the system parameter setting is accurate and the sterilization device is set to automatic mode.
(6) filling
1. Wash and disinfect the bottle.
Bottle with the acceptance of the chlorine-antiseptic for 3 ~ 5 mg/g k pure water rinse the bottle, with disinfectant, metering pump in a certain concentration of production and sampling interval of 2 h 1 times the content of active chlorine in water.
2. Cover cleaning and disinfection.
After finishing device for cap by neatly placed into the chlorinity for 3 ~ 5 m g/k g implementation spray disinfection disinfectant spray area, through the hot water rinse clean area, after the last use sterile dry compressed air to cover both inside and outside surface, into the screw cap within the device.
3. Filling temperature.
In the beverage bottle, outlet temperature of the disinfection device shall be installed in 8 to 9 + l ℃, the temperature of the test bottle after bottle center must have 85 ℃ to be able to filling capping operation.
(7) the following products are used as waste products:
1. Body deformation and abrasion;
2. Insufficient capacity;
3. Impurities of contents;
4. Slanting cover and high cover.
(8) cooling and cooling
1. The chlorine content of the cooling water is 3 mg/k g, and the disinfectant can be added to the production in time, so that the content of disinfectant can be reached to the standard, and the water changed according to the required water changing time standard.
2, segmented spray gradually cool down, make the products out of the spray after the temperature is not higher than 4 0 ℃. The compressed air is used to dry the bottle and bottle cap, which conforms to the standard of spout and set.
(9) spout
Content: on the date of the month;
Location: side of bottle cap; The quality of
Requirements: clear, proper, fit and secure.
(10) boxing and folding plates
Quality requirements: the quantity needs to meet the relevant requirements, the paste is reliable, clean, beautiful, the outer surface of the box is clear. The stack is then implemented according to relevant standards.
III. Analysis of quality defects of PET bottles and measures taken
Heat PET bottle filling doesn't contain the CO2 at 88 ℃ high temperature gas drinks, will produce negative pressure lead to soften and deformation, as well as its moisture absorption will be affected with damp be affected with damp in the inventory, so we in the 0.5 L. PET bottle hot self-inspection requirements in the production of clean and transparent appearance, acuity 0.26 mm plastic distribution, 92 ℃ hot filling and spray cooling to room temperature deformation, shrinkage rate of 3.0% or less. When we use the French company Sidel to blow out the bottle, the common handicraft defects and the measures taken are analyzed as follows:
(1) deformation of the side plate of the bottle
After heat PET bottle in hot filling, use cold water spray cooling to room temperature, the bottle side panel bulge outward deformation, its thermal performance is bad, is because the bottles when forming the amorphous proportion is too large, due to the crystallization of PET polymer chain contract, when the crystallinity reach a certain proportion, rearrangement of molecular chain or crystal that lead to deformation, analysis the reason often is: the mold temperature is too low, need to improve the oil temperature; Normal oil temperature is 158 ℃ to 159 ℃, if the oil temperature higher than 161 ℃ oil Louis coke, causing oil stuck, to clean oil. The billet is not heated enough to raise the temperature of the billet. Normal billet temperature is 129 ℃, otherwise easy to cause the bottle atomization. The plastic distribution is uneven, the heating ratio and preblowing position are adjusted to change the plastic distribution. In normal circumstances, the plastic distribution side plate is more than 0.40 mm, and the upper shoulder and the angular part are greater than 0.26 mm; The heat setting time is too short to reduce the flask speed. Of course, these are not static and need to be taken together and taken together. For example: should the customer filling 83 ℃, 83 ℃ for 10 minutes after cooling deformation demands, we were using the SB016 bottle blowing machine blown half the 0.5 L white bottle, use Shanghai zijiang ZJE - 59 bottle preform bottle blowing, usually need to increase the oil temperature to 162 ℃, the billet temperature to 132 ℃, to ensure that no deformation.
(2) the shrinkage rate is greater than or equal to 3.0%
Heat PET bottle filling said it in cold water volume V1, with 92 ℃ hot water filling according to its capacity of V2 shrinkage rate for the V1, V2 / V3 as a reduction of 3.0% or more, then the bottle volume shrinkage is too big, in addition to the above reasons, 3.1 it is also possible that the holding system sealing ring damaged, the internal and external pressure imbalance, need to replace the sealing ring; Or the oil road is blocked, causing the bottle body to be heated and not uniform, then need to clean the oil road.
(3) the bottle is atomized and bleached
When the PET in the amorphous state, is transparent, crystal between 80 ℃ to 250 ℃, 180 ℃ or so crystallization low viscosity, high polymer chain rearrangement small resistance, crystallization speed, degree of crystallinity; When the PET crystallinity is above 45 %, it can cause the body to atomize, so it needs to adjust its crystallinity.
1. When the whole bottle body is atomized, it is because the temperature is too high, which needs to be in the heat setting process, to reduce the heating temperature and blank temperature set by heating setting.
2. When the bottle body of the PET bottle is partially atomized, it is the corresponding part of the temperature is too high, which should reduce the proportion of heating in the corresponding area or reduce the number of heating lamp tube. The body part of the bottle is in the stretch pre-blow molding stage, because the stretching too fast causes the plastic distribution uneven, or the plastic temperature is too low when stretched, causes the part of the PET bottle to be white. This requires increasing the heating ratio or increasing the number of heating tubes in the corresponding parts. In addition, the whole bottle is white and the heating billet is re-used to blow the bottle again.
Conclusion language
At present, the production process of PET bottle has been quite mature, and PET bottle has become the leading packaging product for worldwide successful products and beverage market. But the ability to obtain high-quality PET bottles and continuously meet people's new requirements must be coordinated with each other in terms of materials, processes and equipment.