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Material Guide

Through continuous cooperation and communication with customers all over the world, Ailin has obtained feedback from customers, helping us to improve product quality and safety. The control of raw materials in Ailin production line ensures the high quality of water bottles/tumblers.

Stainless steel is the abbreviation of stainless acid-resistant steel, and the steel grades that are resistant to weak corrosive media such as air, steam, water, or have stainless properties are called stainless steel.

Generally, ordinary stainless steel is divided into three categories according to the metallographic structure: austenitic stainless steel, ferritic stainless steel, and martensitic stainless steel.

1.Austenitic stainless steel

The matrix is mainly composed of austenite structure (CY phase) with face-centered cubic crystal structure, non-magnetic, and it is mainly strengthened by cold working (and may lead to certain magnetic properties) stainless steel. The American Iron and Steel Institute is marked with numbers in the 200 and 300 series, such as 304.

2.Ferritic stainless steel

The matrix is mainly ferrite (a phase) with a body-centered cubic crystal structure. It is magnetic and generally cannot be hardened by heat treatment, but cold working can make it slightly strengthened. The American Iron and Steel Institute is marked by 430 and 446.

3.Martensitic stainless steel

The matrix is martensitic (body-centered cubic or cubic), magnetic, and its mechanical properties can be adjusted by heat treatment. The American Iron and Steel Institute is marked with 410, 420 and 440 numbers. Martensite has an austenite structure at high temperature, and when cooled to room temperature at an appropriate rate, the austenite structure can transform into martensite.

What kind of stainless steel is not easy to rust?

There are three main factors affecting the corrosion of stainless steel:

1.The content of alloying elements

Generally speaking, steel with a chromium content of 10.5% is not easy to rust. The higher the content of chromium and nickel, the better the corrosion resistance. For example, the content of nickel in 304 materials should be 8-10%, and the content of chromium should reach 18-20%. Such stainless steel will not rust under normal circumstances.

2.The smelting process of the production enterprise will also affect the corrosion resistance of stainless steel.

Large stainless steel factories with good smelting technology, advanced equipment and advanced technology can guarantee the control of alloy elements, the removal of impurities, and the control of billet cooling temperature. Therefore, the product quality is stable and reliable, with good internal quality and is not easy to rust. On the contrary, some small steel mills have backward equipment and backward technology. During the smelting process, impurities cannot be removed, and the products produced will inevitably rust.

3.External environment, dry and well-ventilated environment is not easy to rust.

The air humidity is high, continuous rainy weather, or the environment with high pH in the air is easy to rust. 304 stainless steel, if the surrounding environment is too bad, it will rust.

Plastic manufacturing process

Crude oil and natural gas are mined first, and then sent to refineries to extract many kinds of substances, including the main components of plastics, that is, ethane is extracted from petroleum, and propane is extracted from natural gas. Ethane and propane are sent to cracking plants to be broken down into molecules, ethane is used to make ethylene, and propane is used to make propylene. Then, catalysts are added to combine the molecules to form resin polymers. Because of this structure, plastics are easy to shape under high temperature and pressure.

Polymerization turns ethylene into polyethylene, and propylene into polypropylene. These resins are melted and cooled, and then cut into plastic raw material pellets. The plastic pellets are sent to factories to be heated to make various plastic products.

Most of the plastic raw materials are transparent or milky white. Various plastic products require various colors for use or design, which requires dyeing during plastic processing; the common dyeing method is to mix a certain proportion of color masterbatch or toner in the raw materials before production, and let the raw materials and color masterbatch or toner melt together in the injection molding machine to produce the desired product color.

Plastic products of various shapes and sizes are used in daily life. The main production method of these plastic products is injection molding. The three elements needed in this process are plastic raw materials, molds, and injection molding machines. The injection molding process is to put raw materials into the machine hopper, mix and melt them in the injection molding machine, and then fill the raw materials into the mold. The raw materials are quickly cooled and formed in the mold, and finally the mold is opened to take out the product.

Another common processing method is blow molding. All kinds of plastic bottles, cans, barrels, etc. are all blow molding. It is well understood that after the raw materials are melted, they are blown up in the mold to form them.

The most intuitive difference between injection molding and blow molding is that injection molding products are solid cores, while blow molding is hollow cores.


Different materials

PET (polyester): also called polyester resin, raw material is milky white or light yellow, good transparency, non-toxic, high density, high hardness, wear resistance, but not resistant to hot water soaking, not resistant to alkali and other characteristics, the use temperature is 65 ℃ ~ -20 ℃, more than this temperature is easy to release harmful substances, cannot be used repeatedly for a long time, mainly used in beverage bottles in packaging materials, mineral water bottles, shells and accessories in electronic appliances, etc.

HDPE (high-density polyethylene): also known as low-pressure ethylene, raw material is white, non-toxic and tasteless, with low density, good toughness, acid and alkali resistance, but poor anti-aging performance, difficult to clean and do not recycle, mainly used for detergent packaging bottles, wire and cable sheathing, etc.

PVC (polyvinyl chloride): also known as adhesive film, raw material is yellow translucent, good transparency, high strength, good flexibility, not brittle, etc. PVC is divided into soft and hard, the difference between them depends on whether softener is added, PVC itself is non-toxic, if plasticizers, anti-aging agents, etc. are added, it will be toxic, so soft PVC is non-toxic, hard PVC is toxic, mainly used in packaging materials, pipes, doors and windows in the building materials industry, etc.

LDPE (Low Density Polyethylene): also known as high pressure polyethylene, the raw material is milky white, tasteless and non-toxic, with good transparency, good flexibility, alkali resistance, but poor heat resistance, etc. The density is the lowest among all polyethylenes, and it will release toxic substances when it exceeds 110°C. It is mainly used for plastic wrap, plastic film, etc.

PP (polypropylene) : also known as pleated plastic, has a low density, transparent and light raw material appearance, non-toxic and tasteless, high strength and elasticity, chemical resistance, collision resistance, high temperature resistance of 100-120 degrees Celsius, and can be heated in a microwave oven.

PS (polystyrene): also known as hard glue, has a higher hardness than PP. The raw material has high light transmittance, is colorless and odorless, and is easy to dye, but its toughness is poor, it is easy to be brittle, and harmful substances will be released when the temperature exceeds 70°C.

PA (polyamide): also known as nylon, has no code name. Its raw materials are non-toxic and odorless, with good toughness, wear resistance, heat resistance, and chemical resistance.

ABS plastic is a compound of acrylonitrile (A), butadiene (B) and styrene (C).

Other categories, code-named 7, include acrylic, polycarbonate, polylactic acid, etc. The characteristics of these plastics are that they cannot be heated in a microwave oven, cannot be sterilized at high temperature, and cannot be directly exposed to the sun, because they may release bisphenol A and cause harm to the human body.

Tritan, full name Tritan Copolyester, is a new generation of copolyester product developed by Eastman Company.

It will not release bisphenol A during use, meets environmental protection requirements, has excellent impact strength, excellent chemical resistance, and hydrolysis resistance, and can hold high-temperature beverages at about 100 degrees Celsius.


Simple test

If you want to distinguish various plastic materials more clearly, you can distinguish them by burning. The burning test is to burn various plastics, observe the characteristics and changes that occur during this process, and then judge the plastic material. The observed states are the state of leaving the fire source, burning smell, flame color, state after burning, and flammability. The burning test is completely based on the special effects of plastics, and cannot be used as a scientific basis for identifying plastics.


PET burns black smoke and has a sour taste

PP can burn all the time, the flame is yellow at the top and blue at the bottom, with a candle smell

PS can also burn all the time, the flame is yellow and black smoke, there is carbon dust after burning, and there is a smell of pine oil

ABS can burn quickly and continuously after being ignited, the flame is yellow and black smoke, softens after burning without dripping, and has a strong rubber smell

PC is relatively difficult to burn, and it will go out when the fire is removed. The flame is a small amount of black smoke, which softens and foams after burning, and has no special smell;

The flame of PE is yellow at the top and blue at the bottom, softens and drips after burning, and has the smell of burning paraffin; (have you ever burned a plastic bag when you were a child, do you forget the feeling of dripping, do you remember the pain when dripping on your hands?)

PA is not easy to burn, and it will go out when it leaves the fire source. The flame is yellow and gray smoke. After burning, it foams and drops, and has the smell of sheepskin and nails;

PVC is not easy to burn, and it will go out when it leaves the fire source. The flame is blue at the top and green at the bottom with smoke. It is difficult to soften after burning, and has a pungent sour smell; (the shrink film on the packaging, the hard one is PCV)