Molding of polypropylene foam, the difference between polyethylene foam and polystyrene foam

Polystyrene plastics are widely used in optical instruments, chemical departments and daily necessities, and are used to make tea trays, sugar jars, soap boxes, cigarette boxes, student rulers, combs, etc. Due to its certain air permeability, when made into film products, it can be used as a good food packaging material. If you want to know more about it, you can consult Hangzhou Fangyuan Plastic Machinery Co., Ltd., thank you!

First, the density is different.

1. Polyethylene foam: the density is small, the minimum can be reached, the recovery rate is high, and it has an independent bubble structure. The surface water absorption rate is low, and the anti-permeation performance is good.

2. Polystyrene foam brother Li plastic: the apparent density is kg m3, and the volume of each cubic meter contains 300-6 million independent closed bubbles, and the volume of air contained is more than 98%, due to the small thermal conductivity of air.

Second, the water absorption is different.

1. Polyethylene foam: low surface water absorption and good anti-permeability.

2. Polystyrene foam: large porosity and high water absorption.

Third, the scope of application is different.

1. Polyethylene foam: the joint plate of the expansion joint of the earth highway, the waterproof plate of the joint of the road and bridge, the expansion joint plate of the embankment, dam protection, dissipation barrier, slope protection and retaining wall of water conservancy projects, the waterproof joint plate at the bottom of hydropower, thermal power, engineering and water tower, and the joint filling plate of the settlement joint and frame structure for construction.

2. Styrofoam: construction, insulation, packaging, freezing, daily necessities, industrial casting and other fields, the manufacture of exhibition venues, commodity cabinets, advertising signboards and toys, mainly used in the external insulation of the wall, the insulation of the external wall and the floor heating.

Polyethylene foam is made of polyethylene resin as the main body, plus foaming agent, crosslinking agent and other additives, which is a very important cushioning material. It has a small density, the smallest can be reached; Low cushioning, heat resistance and water absorption; Stable chemical properties and not easy to corrode; Good mechanical properties, tough, flexible, friction resistance; Good processing performance, easy to form; **Cheaper and other advantages. Polyethylene foam is widely used in the packaging of precision instruments, household appliances, glass and ceramic products, handicrafts, valuables, etc.; It can be made into a cushioning liner as a packaging lining material; It can also be made into buffer bags, buffer board boxes and other packaging containers; It can also be made into insulated containers for frozen food and hot food.

Polyethylene foam has good chemical resistance and will not cause rust and corrosion of goods in direct contact with the goods during packaging, so it can reduce the packaging volume and the floor area of the goods, and reduce the handling cost and storage costs.

Most of the highly foamed polyethylene has a closed-cell structure, which is not hygroscopic, and the goods packaged in it will not be eroded by wind and rain even if they are left outside: the cushioning properties of the foam itself will not be weakened. Polyethylene foam is usually used as the packaging lining material.

Different products can be used in different forms, such as upper and lower padded type, both side padded type, surrounded padded type, appearance matching type, etc. Different commodities should also choose polyethylene foam with different characteristics. In agriculture, the use of polyethylene foam is not small.

As a nursery, vegetables, melons and fruits and other greenhouses, it has the advantages of firmness, heat preservation, good weather resistance, and longer service life than non-foaming polyethylene and polyvinyl chloride films, but the ultraviolet transmittance is only 1 2, which can be used as the wall of the cold-proof shed, used for night heat preservation and shading cultivation.

The production process of polypropylene foam material is that it can be foamed at lower temperatures. In order to reduce the processing cost and improve the foaming conditions, it is necessary to develop a preparation method of polypropylene foaming material, reduce the lower limit of polypropylene foaming temperature, broaden the foaming temperature range of polypropylene, that is, the temperature range that can be foamed, and obtain a foam material with consistent cell morphology and large cell density.

Characteristics of polypropylene foam production processPolypropylene PP is one of the most widely used industrial polymer materials, with the advantages of high melting point, high tensile modulus, high density, etc., compared with polyethylene foam, polypropylene foam has good thermal stability and high chemical resistance, and is widely used in industrial fields such as packaging insulation and auto parts, but the high crystallinity and linear molecular structure of polypropylene lead to a narrow processing temperature range.

At present, most of the studies focus on reducing the cell size and improving the porosity, such as adding nucleating agent to improve the nucleation efficiency of polypropylene and using co-foaming agent to improve the porosity of polypropylene, but how to induce polypropylene foaming under low temperature conditions to obtain foam materials with consistent cell morphology and high cell density are not considered.

Polyethylene foam material is a new type of environmentally friendly packaging material with high strength cushioning and anti-vibration ability, it is formed by butane foaming and adding two kinds of auxiliary materials, industrial or medical ultra-fine talc and food anti-shrinkage agent monoglycerides, the whole production process is a physical change, so EPE is non-toxic, environmentally friendly, EPE has high elasticity, and is rich in toughness but not brittle, is currently the world's more advanced, environmentally friendly interior materials.

The surface is soft, white, pleasing to the eye, with light weight, heat insulation, shockproof and sound insulation, corrosion resistance, strong anti-aging ability, pink EPE raw materials with static agent, but also has significant anti-static function, because of its light weight makes the packaging products greatly reduce transportation costs.

Polyethylene foam is a material that is easy to process and handle. Pearl cotton is a semi-rigid foam composed of high-pressure polyethylene through physical foaming to produce countless closed bubbles, and the foaming ratio is 30-40 times. There are various specifications of EPE shapes, sheets, coils, tubes, rods.

EPE has excellent shockproof, dustproof, moisture-proof, heat insulation, sound insulation, heat preservation, acid-proof, and anti-static properties.

Expanded polystyrene board (EPS) is an insulated molded polystyrene foam with low weight and very low thermal conductivity.

Its main technical requirements are as follows:

Thermal conductivity w (m?k） ≤

Performance density (kg m2).

Tensile strength mpa perpendicular to the face direction

Dimensional stability %

Polystyrene foam is made of polystyrene resin as the main body, adding foaming agents and other additives, and it is currently the most used cushioning material. It has a closed-cell structure, low water absorption, and excellent water resistance; The density is small, generally; Good mechanical strength and excellent cushioning performance; Good processability, easy to mold; It has the advantages of good colorability, strong temperature adaptability, excellent radiation resistance, and high dimensional accuracy and uniform structure. Therefore, it has a high share in exterior wall insulation.

However, when burned, styrene gas is released that pollutes the environment. In the profession of architecture, it is a B-grade material.

Polystyrene foam is widely used in the buffer packaging of various precision instruments, meters, household appliances, etc., and can also be directly made into cups, plates, boxes and other packaging containers to package items. Good processability, easy to mold; Good colorability, strong temperature adaptability, excellent radioactivity and other advantages.

Polypropylene plastic: a thermoplastic resin made from the polymerization of propylene. There are three configurations: iso-gauge, unregulated and inter-regulated, and industrial products are mainly composed of iso-gauge substances.

Polypropylene also includes copolymers of propylene with a small amount of ethylene. It is usually a translucent colorless solid, odorless and non-toxic. Due to the regular structure and high crystallization, the melting point is as high as 167, heat resistance, and the products can be sterilized by steam is its outstanding advantage.

density, which is the lightest general-purpose plastic. Corrosion resistance, tensile strength 30MPa, strength, rigidity and transparency are better than polyethylene. The disadvantage is that the low temperature impact resistance is poor, and it is easy to age, but it can be overcome by modification and adding antioxidants.

Features Non-toxic, odorless, low density, strength, stiffness, hardness and heat resistance are better than low-pressure polyethylene, has high bending fatigue resistance, can be used at about 100 degrees. It has good electrical properties and high-frequency insulation, which is not affected by humidity, but becomes brittle, wear-resistant, and easy to age at low temperatures. It is suitable for making general mechanical parts, corrosion-resistant parts and insulating parts.

Common acids and alkali organic solvents have little effect on it and can be used in tableware.

Since it is foam, it must be foamed. Some are one-time foam molding and require foaming molds. Some are cut and glued with foam sheets.

The most common plastic foams are 1. Polystyrene foam, which is used in the largest amount. This is the kind of white pollution and disposable lunch boxes that I used to talk about. 2. Polyurethane foam, there are many types of polyurethane foam, both soft and hard.

3. Rubber-based foams, such as foam tapes, are mostly EPDM rubber and butyl rubber. 4. Polyethylene and polypropylene plastic foams. 5. Other polymers.