Table of Contents
The definition of glass is that it is a special state between the crystalline and liquid states, obtained by supercooling the molten body. Its internal energy and configuration entropy are higher than the corresponding crystalline state, and its structure is short-range ordered and long-range disordered, brittle and transparent.
In 1500 BC, the Egyptians first manufactured glass containers. Afterwards, advanced glass and glass container manufacturing equipment were continuously introduced.
The glass industry has gradually achieved mechanization and automation, and glass containers have been widely used and widely used in the packaging industry due to cost reduction.
As a packaging material, glass has various excellent characteristics: transparency, hardness, pressure resistance, high barrier, corrosion resistance, heat resistance, and excellent optical properties; Packaging containers of various shapes and sizes can be made using various molding and processing methods. The production of glass has abundant raw materials, low prices, and is easy to recycle and reuse.
Glass has always been a commonly used packaging material in industries such as food industry, chemical industry, stationery, medicine and hygiene. At present, the use of glass accounts for about 10% of the total amount of packaging materials.
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Packaging characteristics of glass materials
As a food packaging material, glass has an outstanding advantage of excellent chemical stability. It does not interact with packaged food and has good packaging safety, especially suitable for packaging products with high safety and hygiene requirements such as food and drugs.
The commonly used glass density for packaging is around 2.5g/cm, which is much higher than other packaging materials except for metal. The wall thickness of glass products is relatively large, and their weight is greater than that of metal packaging products of the same capacity. These characteristics increase the transportation costs of glass products and food production, which is not conducive to the storage, handling, and consumer carrying of packaged food.
Glass has excellent transparency, which can fully display the sensory quality of the food inside.
High temperature resistance
Glass is resistant to high temperature, can withstand sterilization, disinfection, cleaning and other high temperature treatments during processing, and can adapt to microwave processing of food and other hot working. However, glass materials have poor adaptability to thermal shock caused by sudden changes in temperature, especially when the glass is thicker and the surface quality is poor, it can withstand less sudden changes in temperature difference.
The transmittance of Borui to other substances is almost zero, which can effectively protect the aroma components in food, which is a prominent advantage of it as a food packaging material.
High compressive strength
Glass has a high compressive strength (200-600MPa), but a lower tensile strength (50-200MPa), high brittleness, and low impact strength.
Rich raw materials
There are abundant sources of raw materials for producing glass. The price is low, and it also has the characteristic of being recyclable and reusable. Waste glass products can be easily processed and molded, and can be recycled and reused by melting in a furnace to form products. It can save raw materials and reduce energy consumption. Glass can be processed into containers of various shapes and structures, which are easy to color, have a bright appearance, and are used for food packaging with good beautification effects.
Varieties of packaging glass
There are many types of glass, such as flat glass, container glass, vessel glass, decorative glass, etc. Packaging glass mainly refers to container glass, which is used to manufacture packaging bottles or cans for various beverages, food, drugs, cosmetics, and chemical reagents.
This kind of glass should have certain chemical stability, thermal stability, strength and transparency or shading, and the price is relatively cheap, which is easy to recycle. In the above types of glass, soda lime glass is commonly used as packaging materials, followed by borosilicate glass.
Sodium calcium glass
Sodium calcium silicate glass, abbreviated as sodium calcium silicate glass, is the most versatile and versatile type of glass. Sodium calcium glass is easy to melt and process, and its price is cheap.
Generally, glass with no special requirements for heat resistance and chemical stability is used, such as ordinary bottle glass, ware tread glass, flat window glass, lighting glass, etc.
Borosilicate glass is generally referred to as hard glass. The glass has good chemical stability, low coefficient of thermal expansion and low manufacturing cost.
Especially suitable for packaging neutral, acidic, and alkaline liquids that are prone to contamination, such as injections, saline water, etc., and also suitable for packaging high-end cosmetics.
Types of glass packaging
Glass packaging containers are commonly referred to as glass bottles, which have a wide variety of types and can be roughly classified as follows:
(1) They are divided into molded bottles and tube bottles according to their manufacturing methods.
(2) According to color, it can be divided into colorless transparent bottles, colored bottles, and opaque opaque glass bottles.
(3) There are circular bottles and special-shaped bottles according to their shape.
(4) According to the size of the bottle mouth, there are narrow necked bottles and wide necked bottles (generally divided by the diameter of the bottle mouth of 30mm).
(5) According to the form of bottle mouth, there are ground mouth bottles, ordinary corked bottles, spiral cap bottles, protruding ear bottles, crown cap bottles, and rolling cap bottles.
(6) According to their usage, they are divided into food packaging bottles, beverage bottles, wine bottles, infusion bottles, reagent bottles, cosmetics bottles, etc.
(7) According to the volume integral, there are small bottles and large bottles (with a capacity of 5L as the boundary).
(8) According to the number of uses, it can also be divided into disposable bottles and recyclable bottles.
- According to the thickness of the bottle wall, it can be divided into thick walled bottles and lightweight bottles.
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