Liquid silicone for molds is a two-component compound, mixed with moisture or cross-linking agent through catalyst action at room temperature or under heating, and vulcanized into elastic silicone rubber that can be used for making molds. Liquid silicone for molds is used to make silicone molds. It is a mold material for decoration, building materials, handicrafts, tires, industrial casting, food, etc., and is used for the mass production of replica products. Mold silicone raw material belongs to chemical products, which is a new type of environmentally friendly material mixed with various materials. During the production process, no inert molecules will be released, nor will they be volatile, and will not pollute the environment. Liquid silicone rubber for molds is an ideal material for elastic molds. The mold making is simple and easy to demould and the production cost is low.
Synonyms: Liquid silicone rubber for molds, liquid silicone for mold making,Liquid silicone rubber for moldmaking, Two-component vulcanized silicone, RTV-2 silicone， liquid mold silicone, Two-component liquid rubbers for moldmaking
Liquid silicone for molds are composed of low-viscosity polysiloxane as the main raw material, together with fillers, cross-linking agents and catalysts. Usually, silicone polymer, crosslinking agent, and catalyst can be used to make mold silicone. In order to meet the performance requirements of different products, such as fillers will increase the tear strength. The additives need to be determined according to the performance requirements of the product. Liquid mold silicone rubber is composed of A/B two-component, wherein A component contains a catalyst, and B component contains a crosslinking agent. At room temperature or under heating, the two components of A and B are mixed according to a certain ratio (the ratio is usually: 100:2, 1:1, or 10:1), which can be selected according to the product performance requirements) to undergo a crosslinking reaction, and become an elastomer after vulcanization .
Liquid silicone for molds can be divided into two categories: Addition-cure type liquid mold silicone rubber and Condensation-cure type liquid mold silicone rubber. The main difference is the catalyst, the proportion, and whether there are by-products and odor after molding. Basic components and differences of addition and condensation cure liquid silicone for mold:
Components
Addition cure liquid silicone for molds
Condensation cure liquid silicone for molds
Base Polymer
Polydimethylsiloxane containing vinyl
Polydimethylsiloxane containing hydroxyl group
Cross-linking agent
Polydimethylsiloxane containing hydroxyl group
Alkoxy silanes or alkoxy siloxanes
Catalyst
Platinum series compound
Organo-tin compound
Deep curing additive
Not required
Water, alcohol, polyol, etc.
Reaction inhibitor
Alkynols
Low molecular containing =Si-OH compound
Reinforcing agent
Silica, MO silicone resin containing vinyl
White carbon black, quartz powder, diatomaceous earth, calcium carbonate, etc.
Additive
Pigment, internal release agent, heat stabilizer, etc.
Pigment, internal release agent, heat stabilizer, etc.
Various condensation/addition cure liquid silicone for molds are as follows:
Condensation cure silicone
Before curing
Product parameters
YR-M10A/B
YR-M13A/B
YR-M15A/B
YR-M20A/B
YR-M25A/B
YR-M25A/B-2
YR-M35A/B
YR-M45A/B
YR-M45A/B-2
YR-M52A/B
YR-M60A/B
YR-M75A/B
Appearance
White
Greyish white
Greyish white
Translucent
Translucent
Greyish white
Greyish white
Greyish white
Greyish white
Greyish white
Greyish white
Greyish white
Viscosity (pa·s)
10
13
15
20
25
25
35
45
45
52
60
75
Curing agent
0.5%
0.5%
5%
5%
10%
5%
5%
5%
5%
10%
1%
0.5%
Pot Life (mins)
30
60
30
90
90
40
40
40
90
35
120
180
Curing time (25°C*hrs)
8
24
24
24
24
24
24
24
24
24
24
24
Reaction inhibitor
No
No
No
No
No
No
No
No
No
No
No
No
After curing
Appearance
White
Greyish white
Greyish white
Translucent
Translucent
Greyish white
Greyish white
Greyish white
Light blue
Greyish white
Greyish white
Greyish white
Density (g/cm³)
1.28
1.17
1.16
1.10
1.07
1.14
1.19
1.19
1.13
1.16
1.4
1.32
Hardness Shore A
40
50
30
12
38
30
15
20
30
36
88
83
Tensile strength Mpa
2.5
2.0
3.5
2.9
4.8
4.3
3.0
4.2
3.6
4.3
7.5
6.0
Elongation at break(%)
170
170
180
540
230
300
450
400
300
260
70
65
Tear strength (kN/m)
3
3
3
15
17
15
16
18
23
13
3
3
Linear shrinkage (%)
0.5
0.3
0.5
0.3
0.3
0.3
0.3
0.3
0.3
0.3
1.0
1.0
Note
Under the condition of 25 ℃, since the viscosity will increase with time, the operation needs to be completed in a short time.
With the industrialization of the silicone industry, liquid silicone for molds has the characteristics of convenient operation, low production cost, and high mold precision, it has largely replaced metal and wood and has become one of the important materials for mold making.
Condensation cure silicone properties:
■ Timeliness: Under the condition of 25C°, vulcanize into elastomer in 8-24 hours. Appropriately increase the amount of curing agent and humidity, and the curing speed will be faster.
■ Operability: It can be operated by hand or machine, and the viscosity, hardness, operation time, and color can be adjusted according to requirements. Even amateurs without any experience can be easy to make the master pattern. ■ Fluidity: Excellent fluidity, easy to defoam, can reproduce detailed textures, and the reproduction effect is good. ■ Low cost: Condensation-cured silicones use organotin as the curing agent, which is less expensive than addition-cured silicones that use platinum catalysts. ■ High and low temperature resistance: liquid silicone for molds can withstand the high temperature of 200 degrees, is not brittle at the low temperature of -50 degrees, maintains good flexibility, and the simulation effect is very good. ■ Mold release performance: Compared with PVC molds, iron molds, aluminum molds, resin molds, etc., because liquid silicone for molds has good flexibility and elasticity, it is easy to release the mold without damaging the characteristics of the original mold structure, especially suitable for making deep grooves, parts with more complex patterns. ■ Replication performance: It has an excellent simulation and extremely low shrinkage, and basically does not lose the dimensional accuracy of the parts. ■ Stability: The liquid silicone for molds has a long service life, is not easy to deform, and can be turned over 8000-1000 times. ■ Simulation performance: It is used to make silicone molds with fine patterns and complex structures, clearly outline the fine lines on the product surface, and reproduce the fine features on the prototype parts.
Addition cure silicone properties:
In addition to the characteristics of condensation cure silicone, addition cure silicone has the following characteristics:
■ Deep curing: It is not limited by the thickness of the device, and can be deeply vulcanized. ■ Higher tear strength: Tensile, tear strength is stronger than condensation cure silicone. ■ Environmental protection and safety: Addition mold silicone adopts platinum catalyst. After vulcanization, the silicone mold has no irritating smell and is non-corrosive. It can contact human skin for a long time and has passed FDA food-grade certification. ■ Lower shrinkage rate: The shrinkage rate of addition cure silicone is ≤0.1%. No by-products will be produced during the cross-linking and curing process, and the size is more stable and the precision is higher. ■ Faster curing time: It can be cured at room temperature or heated to speed up the curing speed without any adverse effect on the cured colloid.
Application of liquid silicone for molds
Low-viscosity of liquid silicone for molds has excellent fluidity. When used, the liquid silicone for molds can automatically fill the entire mold, perfectly copying the texture lines on the mold, and the simulation is very realistic, which is convenient for making replicas. After vulcanization and molding, the liquid silicone for molds can be demolded quickly, and the desired product can be reproduced within 20 hours, which reduces many unnecessary processes, which is conducive to shortening the production time and reducing production costs.
Condensation cure liquid silicone for molds is also called "industrial grade mold silicone rubber", which is mainly used in: ★ Construction and home decoration: Brick carving, cultural stone, relief, gypsum building materials, etc. ★ Crafts: candles, toys, soap, resin crafts, plaster crafts, etc. ★ Composite materials and parts: tires, electronic accessories, car decorations, etc. ★ Simulation of plants and animals: Wax figures, cabbage decorations, zodiac signs, cartoon characters, Buddha statues, etc.
Addition cure liquid silicone for molds is also called “food grade mold silicone rubber”, mainly used in: ★Food molds: Ice cream, biscuits, chocolate molds, ice sculptures, sugar cubes, etc. ★Precision parts: Precision instrument prototype casting, auto parts, aerospace parts, military supplies, ship-shape, glass strengthening furnace, etc. ★Human body silicone: silicone dolls, simulation robots, simulated human prostheses, facial features, etc.
Why choose Yongrui as your parner？
Professional
12 years experience manufacurer condensation/addition cure silicone.
OEM/ODM
All kinds of viscosity of condensation/addition cure silicone can be produced according to customer requirements.
Quality certificate
Passed SGS, ROSH and FDA certification. That means that we guarantee to provide you with high-quality condensation/addition cure silicone.
Mass Production
We uses advanced machinery and equipment to produce and provide condensation/addition cure silicone with stable performance and quality assurance.
The product contains some fillers. If it is stored for a long time, the filler may sink to the bottom. Please stir it as evenly as possible before use. The curing agent is easily hydrolyzed in contact with air, please cover the unused curing agent bottle in time. Since the temperature will affect the vulcanization speed of the mold silicone, the dosage of the curing agent can be appropriately changed according to the temperature. When the temperature is low, please try to keep the ambient temperature of the mold silicone rubber at 20C°-30C°, so that it can be vulcanized completely.
Storage conditions:
Prohibition of contact with sunlight. The environment for sealed storage must be ventilated and dry, and the storage temperature is controlled at 0℃-40C°.
Shelf life:
Under the above conditions, the shelf life is usually 12 months. After the shelf life, the experienced personnel can still use it if it is qualified.
Liquid silicone for molds common problems
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Why is the liquid silicone for mold material not resistant to burning?
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After adding a peroxide curing agent to unsaturated resin and resin and resin products, it will react with the resin to generate a lot of heat, resulting in the phenomenon that the mold is not resistant to high temperature. Condensation-type liquid mold silicone rubber can deal with the problem of high temperature resistance by adding a fire-resistant agent. However, due to the temperature resistance of condensation cure liquid silicone for molds is about 70-80 degrees. If the temperature of the product to be produced is higher than 100 degrees, addition cure liquid silicone for molds can be used, and its temperature resistance can reach 280-300 degrees.
Why is the mold seeping oil?
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The mold silicone itself will not emit oil. The main reason for oil leakage is the excessive addition of compound silicone oil (composite of white mineral oil and silicone oil) during the mold manufacturing process. In addition, the excessive addition of curing agents is also one of the reasons.
Why is the mold silicone not dry?
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There are two main reasons why the condensation cure liquid silicone for molds does not dry. 1. The proportion of organotin curing agent is too small or expired curing agent is used. 2. The moisture content that reacts with the liquid silica gel during the mold-making process is low, resulting in incomplete curing of the silica gel. In the case of curing dosage, the curing agent can be accurately weighed with an electronic scale to add the required amount. If the air moisture is not enough, you can add three-thousandths of water to the liquid silicone rubber.
There are two reasons for the non-drying phenomenon of addition cure liquid silicone for molds: 1. Poisoning of silicone rubber. The poisoning reaction of silicone rubber is caused by contact with toxic substances containing sulfur, phosphorus, and nitrogen that pollute the platinum catalyst, resulting in the failure of the normal curing of silicone rubber. 2. The temperature is too low. Since platinum needs temperature to catalyze the reaction, too low temperature will lead to incomplete curing of silicone rubber. Therefore, heating measures can be taken to solve this problem.
Why does mold silicone have less mold turning times?
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In the process of making molds, if excessive silicone oil is added, the molecular weight of silicone rubber will be destroyed, resulting in fewer mold turning times and less durability. For products with small patterns and complex structures, if the mold is opened with a liquid mold silicone with high hardness, the silicone will be very brittle and the number of times mold turning will be less. Therefore, it is necessary to choose liquid mold silicone with a suitable hardness to make molds.
