Glass bottles and cans are packaging containers for food, beverages and many products. They are widely used. Glass is also a kind of packaging material with a long history. With many packaging materials pouring into the market, glass containers still occupy an important position in beverage packaging, which is inseparable from its packaging characteristics that other packaging materials cannot replace.
It can be sealed with a lid or stopper, and can hold various materials of hollow glass products quantitatively. Widely used as packaging containers for beverages, alcohol, chemicals, medicines, cultural and educational supplies, and cosmetics. The glass jars are transparent, easy to clean, have good chemical stability, do not pollute the contents, have high air-tightness, excellent storage performance, and are rich in styles and decorations. They can be recycled and used many times and have abundant sources of raw materials. However, glass bottles are easy to break and have a large weight-to-volume ratio. These shortcomings are gradually improving with the development of process technology.
The production of glass products is the highest in the production of glass bottles. In 1980, the world’s output of glass products was 68Mt, of which the output of glass bottles was 40.8Mt.
From 2000 to 500 BC, humans could make hollow glassware. After the blowpipe began to be used in 200 BC, the oil and wine industries subsequently used hollow glass as containers. During the Roman Empire, the demand for glass containers increased, and most of the products were round-bottomed and must be supported by iron or wooden frames. Later, due to the development of molds for blowing glass, flat-bottom bottles without brackets were produced. From the 5th to 15th centuries, pressing, drawing, and blowing technology developed greatly, laying the foundation for the mechanization of glass manufacturing. In 1867, the German Siemens brothers applied the continuous melting tank kiln of the regenerator to the glass industry, making the mass production of glass bottles possible. From 1880 to 1890, the press-blowing method for manufacturing wide-mouth bottles and blow-blow method for manufacturing small-mouth bottles were invented (see glass manufacturing). The first bottle-making machine driven by an electric motor appeared in 1900. From 1904 to 1905, American M.J. Owens created a fully automatic vacuum suction bottle making machine. Since 1910, the gob feeder began to develop. In 1914, the semi-automatic blowing-blowing process was mature. In 1925, the Hardford-Empel Company of the United States successfully developed an in-line bottle making machine, which was produced by the blowing-blowing method, and later developed to also be produced by the pressure-blowing method. This line-type bottle making machine is still the main model used so far, and is gradually developing in the direction of multiple units and multiple drops.
In the Tang and Song Dynasties, China has used blowpipes to blow hollow glass containers. The modern glass industry was formed from 1904 to 1908. The Shanghai Jinghua Glass Factory, established in 1931, was the first factory in China to continuously manufacture glass bottles and jars using horizontal flame and horseshoe flame regenerator tank kilns and automatic bottle making machines. After the 1950s, a number of large-scale modern bottle factories were built. In the 1980s, in the production of glass bottles and cans, the biggest improvement was the lightweight of glass bottles, which could save raw materials and fuel, increase production speed, and reduce transportation costs.
There are many types of classified glass bottles, and there are many classification methods. ①According to the appearance, there are general bottle cans, handle bottle cans and tube-shaped bottle cans, etc., with a holding capacity of 1ml～25l. ②According to the bottom shape, there are round, oval, square, rectangular, flat and other bottles and cans, mostly round. ③According to the size of the bottle mouth, there are bottles and cans such as wide mouth, small mouth and spray mouth. Bottles with an inner diameter greater than 30mm, no shoulders or less shoulders are called wide-mouth bottles, which are often used to hold semi-fluid and powdery or block solid objects; those with an inner diameter of less than 30mm are called small-mouth bottles, which are often used to hold various fluid objects. ④According to the matching form of bottle mouth and bottle cap, there are continuous thread bottle mouth, cork bottle mouth, pouring bottle mouth, crown cap bottle mouth, rolling cap bottle mouth, plastic cap bottle mouth, and spray bottle mouth. , Press on-unscrew the bottle mouth, side seal-pry open the bottle mouth, glass stopper frosted bottle mouth, handle bottle mouth and tube bottle mouth and other bottles. The size and tolerance of the bottle mouth are standardized. ⑤According to the use requirements of bottles and cans, there are one-time use of bottles and cans and recycling of bottles and cans. Once-used bottles and cans are discarded once they are used; recycled bottles and cans can be recycled multiple times for turnover. ⑥According to the molding method, there are molded bottles and control bottles. The molded bottle is made by directly forming the glass liquid in the mold; the control bottle is made by first drawing the glass liquid into a glass tube, and then processing and forming. ⑦According to the color of the bottles and cans, there are colorless, colored and milky bottles. Most of the glass jars are clear and colorless, which can keep the contents in a normal image. Followed by green and brown. Green ones are usually used for beverages; brown ones are used for medicines or beer. They can absorb ultraviolet light and help protect the contents. The United States stipulates that the average wall thickness of such colored glass bottles and jars should be such that the transmittance of light waves with a wavelength of 290 to 450 nm is less than 10%. A few cosmetics, creams and ointments are packed in opalescent glass bottles.
Raw materials and chemical composition Bottle glass batches generally consist of 7-12 kinds of raw materials. There are mainly quartz sand, soda ash, limestone, dolomite, feldspar, borax, lead and barium compounds. In addition, there are auxiliary materials such as clarifiers, colorants, decolorants, opacifiers, etc. (see glass manufacturing). Coarse particles of quartz are difficult to melt completely; too fine particles will easily produce scum and dust during the melting process, which will affect the melting and easily block the regenerator of the melting furnace. The suitable particle size is 0.25～0.5mm. In order to use waste glass, cullet is usually added, and the amount is usually 20-60%, up to 90%.
The chemical composition of glass bottle glass varies according to its use requirements, molding methods, molding speed, process characteristics and raw material varieties. Most bottles and cans use soda lime silicate glass. The main components of soda lime silicate glass are SiO2, Na2O and CaO. Introducing a proper amount of Al2O3 and MgO can reduce the tendency of glass to crystallize, enhance the chemical stability and mechanical strength of the glass, and improve the forming performance of the glass. The chemical composition of soda lime glass in most countries in the world is: SiO270～74%, CaO and MgO10～14%, Na2O and K2O13～16%, Al2O31.5～2.5%. When manufacturing colorless glass jars, the content of Fe2O3 in quartz sand is very low (usually about 0.03%). In ordinary soda lime glass, adding Cr2O3 and Fe2O3, the glass is emerald green, adding sulfur-carbon or MnO2 and Fe2O3, the glass is brown. Bottles and cans containing medicines require high chemical stability and are made of borosilicate glass. High-end cosmetic bottles are commonly made of crystalline glass containing lead, barium or zinc, some are opalescent glass, and fluoride is generally used as an opacifier.
Quality requirements Glass bottles and cans should have certain performance and meet certain quality standards.
①Glass quality: pure and uniform, without defects such as sand, streaks, and bubbles. Colorless glass has high transparency; the color of colored glass is uniform and stable, and it can absorb light energy of a certain wavelength.
②Physical and chemical properties: It has a certain degree of chemical stability and does not interact with the contents. It has a certain degree of shock resistance and mechanical strength. It can withstand heating and cooling processes such as washing and sterilization, as well as withstanding filling, storage and transportation. It can remain undamaged when encountering general internal and external stress, vibration, and impact.
③Forming quality: maintain a certain capacity, weight and shape, uniform wall thickness, smooth and flat mouth to ensure convenient filling and good sealing. There are no defects such as distortion, uneven surface, unevenness and cracks.
Manufacturing process Glass bottle and can manufacturing mainly includes batch preparation, melting, forming, annealing, surface treatment and processing, inspection and packaging.
①Batch preparation: including storage, weighing, mixing and conveying of batch materials. The batch materials are required to be evenly mixed and have stable chemical composition.
②Melting: The melting of bottle glass is mostly carried out in continuous operation flame tank furnace (see glass melting furnace). The daily output of horizontal flame tank kilns generally exceeds 200t, and the large-scale ones reach 400～500t. The daily output of the horseshoe-shaped flame tank kiln is mostly below 200t. The glass melting temperature is up to 1580～1600℃. The energy consumption of melting accounts for about 70% of the total energy consumption in production. It can effectively save energy by comprehensively insulating the tank, increasing the capacity of checker bricks in the regenerator, improving the distribution of the piles, increasing the combustion efficiency and controlling the convection of the glass liquid. Bubbling in the melting tank can improve the convection of the glass liquid, strengthen the clarification and homogenization process, and increase the output. The use of electric heating in the flame kiln can increase the output and improve the quality without increasing the furnace.
③Forming: Molding is mainly used, using blow-blow method to form small mouth bottles, and pressure-blow method to form wide mouth bottles (see glass manufacturing). Less use of control law. The production of modern glass bottles and cans is widely used in high-speed forming by automatic bottle making machines. This type of bottle making machine has certain requirements on the weight, shape and uniformity of the gobs, so the temperature in the feed tank must be strictly controlled. There are many types of automatic bottle making machines, among which the inline bottle making machine is the most commonly used. This kind of bottle making machine’s gobs obey the bottle making machine, not the bottle making machine obeys the gobs, so there is no rotating part, the operation is safe, and any branch can be parked separately for maintenance without affecting other branch operations (Figure 1 ). The line-type bottle making machine has a wide range of manufacturing bottles and cans, and has great flexibility. It has been developed into 12 groups, double drop or triple drop molding and computer control.
④ Annealing: Annealing of glass bottles and cans is to reduce the residual permanent stress of the glass to allowable values. Annealing is usually carried out in a mesh belt continuous annealing furnace, and the maximum annealing temperature is about 550-600°C. The mesh belt annealing furnace (Figure 2) adopts forced air circulation heating to make the temperature distribution of the furnace chamber uniform and form an air curtain, which restricts the longitudinal air movement and ensures the uniform and stable temperature of each belt in the furnace.
⑤Surface treatment and processing: Generally, the surface treatment of glass bottles and cans is carried out by coating the hot and cold ends of the annealing furnace. The hot-end coating is to place the formed bottle in a hot state (500～600℃) in the atmosphere of vaporized tin tetrachloride, titanium tetrachloride or tin butyl tetrachloride to make these metal compounds in The surface of the hot bottle can be decomposed and oxidized into an oxide film to fill the micro-cracks on the glass surface, prevent the generation of surface micro-cracks, and improve the mechanical strength of the glass bottle. The cold end coating is sprayed with monostearate, oleic acid, polyethylene emulsion, silicone or silane, etc., on the surface of the bottle and can at a temperature of about 100-150℃ at the exit of the annealing furnace to form a lubricating film. In order to improve the wear resistance, lubricity and impact strength of the bottle surface. In production, cold end coating and hot end coating are often used in combination. For large-capacity bottles and cans of more than 1l, some of them are sheathed with foamed polystyrene or polyethylene film. The sheath is heat-shrinkable, and the bottle body is tightly closed after heating. It is tough and elastic, shock-proof and anti-friction. When the bottle is broken, there is no fragment flying, which can avoid personal injury.
Reagent bottles, sample bottles, perfume bottles, etc. equipped with glass stoppers are ground and stoppered with mortar or emery and water as abrasive. High-grade cosmetics and perfume bottles are often subjected to grinding and polishing to eliminate mold marks and increase gloss. High-end wine bottles or art-decorated bottles and cans are corroded by hydrofluoric acid, resulting in diffuse light on the surface and delicate touch. In order to print trademarks and decorations on the glass surface, the glass glaze can be applied to the surface of the bottle and can by color spraying, screen printing, and decals. The glass glaze is baked at 600 ℃, and the glaze is fused with the glass to form a permanent pattern. . If organic pigments are used for decoration, it only needs to be melted and baked at 200～300℃.
⑥Inspection: Detect defective products and ensure product quality. The defects of glass bottles and cans are divided into two categories: glass defects and bottle forming defects. The former includes bubbles, stones, streaks, and color irregularities; the latter includes cracks, uneven thickness, deformation, cold spots, and wrinkles. In addition, it is necessary to check the weight, capacity, dimensional tolerances of bottle mouth and bottle body, internal stress resistance, thermal shock resistance and stress relief degree. Because of the high production speed and large batches of beer bottles, food and beverage bottles, etc., visual inspection can no longer be adapted. There are automatic inspection equipment, such as preselectors (checking the shape and dimensional tolerances of bottles and cans), bottle mouth checkers, and cracks Inspector, wall thickness inspection device, extrusion tester, pressure tester, etc.
⑦Packaging: There are corrugated cardboard box packaging, plastic box packaging and pallet container packaging. All have been automated. The corrugated cardboard box packaging starts from empty bottle packaging to filling and sales, using the same carton. The plastic box used in plastic box packaging can be recycled and reused. Tray container packaging is to arrange the inspected bottles into a rectangular bottle array, move them to the tray and stack them layer by layer, and then wrap them up to the specified number of layers. Generally, it is also covered with a plastic film sleeve, heated to shrink it, wrap it tightly into a strong whole, and then bundle it. This is also called thermoplastic packaging.
Post time: Feb-20-2021