Silicone rubber can be divided into liquid silicone rubber and solid silicone rubber according to the existing types. Their physical properties are different due to different forms, and their applications are also quite different. This paper will discuss the differences between liquid silicone rubber and solid silicone rubber.

Let's talk about solid silicone rubber first. The vulcanized silicone rubber products and silicone compound are solid. The solid silicone rubber we talk about here refers to silicone compound. This kind of silicone rubber is also called high temperature silicone rubber. No matter what kind of vulcanizing agent is used, vulcanization needs to be carried out at high temperature in order to complete vulcanization and obtain ideal physical properties. After vulcanization, solid silicone rubber can be made into various silicone products, which generally have good physical properties. After secondary vulcanization, solid silicone rubber products can generally pass the FDA test and reach the food grade standard. Therefore, solid silicone rubber can be used not only in industrial products, but also in food contact.

There are many varieties of liquid silicone rubber, but they are more unvulcanized original silicone materials, which are all liquid. Because of its sulfur mobility, liquid silicone rubber is easier to form and can be easily made into molds to copy products, which can not be achieved by solid silicone rubber. Liquid silicone rubber can also be made into adhesives for bonding various materials. Most liquid silicone rubber can be vulcanized at room temperature.

Liquid silicone rubber can be divided into condensation liquid silicone rubber and addition liquid silicone rubber according to reaction type. Condensed silicone rubber generally can not reach the food grade standard, while addition silicone rubber generally can reach the food grade standard and has excellent physical properties. Therefore, it is made into liquid silicone products and applied in all walks of life.

difference

If it is made into finished products, it is generally not easy to distinguish.

Raw materials can be seen as a solid and a liquid. Now let's talk about the difference between the two materials:

1. Shape of liquid silicone rubber and solid:

(1) As the name suggests, liquid silicone rubber is liquid and has fluidity.

(2) Solid silicone rubber is solid and has no fluidity.

2. Application fields of liquid silicone rubber and solid silicone rubber:

(1) Liquid silicone rubber is generally used in baby products, kitchen products and medical products, which can directly contact food and human body,

(2) Solid silicone rubber is generally used in daily necessities, industrial miscellaneous parts and auto parts,

3. Safety of solid silicone rubber and liquid silicone rubber:

(1) Liquid silicone rubber is a food grade material with high transparency and safety. It is sealed and fed without vulcanizing agent and other auxiliary materials.

(2) Solid silicone rubber is a transparent environmental protection material. Vulcanizing agent needs to be added during molding to speed up the vulcanization molding time and open mold feeding for molding,

4. Forming method of liquid silicone rubber and solid silicone rubber:

(1) Liquid silicone rubber is injection molded liquid silicone rubber (LSR): its full name is injection molded liquid silicone rubber, and the vulcanization equipment is injection molding machine. The injection molding machine has many advantages, such as very simple process flow (without manual processes such as batching, mixing, cutting and placing in the high-temperature glue process, only one worker needs to take the product), high product accuracy (all manual procedures are replaced by the machine before molding), high output (A / B glue is mixed for molding in a few seconds at a certain temperature), labor saving, power saving, material saving and so on, Can produce all high temperature glue products! It is a mainstream in the development of silicone rubber materials in the next few years.

(2) Solid silicone rubber molding is that the raw materials are solid pieces. After mixing by the mixer, the cutting machine cuts the products into the appropriate size and thickness of the product and mold, and then puts them into the mold. It is molded at a certain temperature under the pressure molding machine. When demoulding, it is similar to plastic products, and the mold also needs to be cleaned.

(5) What is the difference between liquid silicone rubber and solid silicone rubber products

Liquid silicone rubber has high transparency and no peculiar smell. The product has a glue injection port.

Solid silicone rubber transparent bottom, with the smell of vulcanizing agent or other covering vulcanizing agent, and the product has no glue injection port.

Overview of liquid silicone rubber molding

What kind of material is liquid silicone rubber (LSR)?

The utility model relates to a non-toxic, heat-resistant and high recovery flexible thermosetting material.

The rheological behavior is low viscosity, rapid curing, shear thinning and high coefficient of thermal expansion.

It is a double liquid rapid vulcanization material with platinum as vulcanizing agent. It can be produced by injection molding in a large, rapid and repetitive way.

LSR products have good thermal stability, cold resistance, excellent electrical insulation, and will not produce harmful substances during combustion. It is a good substitute for plastics.

And solid silicone rubber.

1. More hygienic and safe

A. Peroxide vulcanization system. (solid silicone rubber)

B. Platinum vulcanization system (liquid silicone rubber)

2. More efficient

3. More labor saving

(processes such as rubber mixing, rubber cutting, manual feeding and flash cleaning are no longer required)

Now liquid silicone rubber instead of solid silicone rubber has increasingly become an irreversible trend. This brings new development opportunities to injection molding.

Residue after LSR combustion.

SiO2 + Cl2 (chlorosilane) -- hydrolyzed to D3, D4, D5 -- polymerized into macromolecules + end capping agent -- liquid silicone rubber

Combustion product: white carbon black (SiO2)

Smoke (silicone oil), the cause of white smoke (SiO2). There is no carbon combustion, and black smoke will appear because of the combustion of carbon compounds.

LSR is currently the safest alternative material for plastics

1. Price problem

The main component of LSR is silicon. The most abundant element on earth is silicon, which can be reused.

2. Environmental issues

LSR is safe and degradable to the environment

3. Health and safety

Nowadays, LSR has gradually come down from the altar of high-end products and is accepted by the general public. Now it is widely used in the production of health products, automobiles, baby products, medical products, diving products, sports equipment, electric products, kitchen appliances, seals, etc.

Development status of liquid silicone rubber industry

The price of raw materials decreased steadily, the consumption increased exponentially, and emerging raw material suppliers sprung up, further promoting the accelerated development of the application of liquid silicone rubber.

LSR feeder works to fully mix component A and component B in an accurate ratio of 1:1. Because some products are colored, it is equipped with color pump unit and color metering part. After component A + B, additives and color are fully mixed, they enter the plasticizing system. This plasticizing screw also has the functions of homogenization and mixing. The mixture is injected into the hot mold through the screw at the mold temperature of 170 ℃ The curing reaction of silicone rubber occurs at ~ 200 ℃.

Difference between LSR molding system and ordinary injection molding machine

1. LSR is a thermosetting material.

2. LSR has good fluidity, so it has low requirements for mold locking force and injection pressure, but higher requirements for glue injection accuracy.

3. LSR is relatively difficult to exhaust, and the exhaust clearance is generally 0.02mm, so it requires higher die accuracy.

4. Barrel and glue feeding cooling.

5. The screw shall be a screw with mixing head.