one component silicone combines best of hcr, lsr.

by:Keyuan     2020-07-02
Heat cured silicone rubber can be roughly divided into two categories, including high consistency rubber (HCR)
And liquid silicone (LSR).
The typical HCR is catalytic with organic peroxide, although the addition-
Curing technology can be used for a limited number of molding and extrusion applications.
Liquid silicone rubber is usually sold in two forms
Composition, the addition of curing material that must be mixed in a specific proportion before injection and curing in the mold. A one-
The component liquid silicone rubber system is introduced, providing the best functions of HCR and LSR (ref. 1).
High-concentration rubber accounts for more than 50% of all silicone rubber products in North America.
This is not an accident.
HCR has some inherent advantages over LSR.
These advantages include: * easy to mix in a mixer or roller mill;
* It is easy to be prefabricated into manageable shapes so that it can be easily introduced into process equipment such as extruder or molding machine;
* Long pot life of fully catalytic compounds (
In the case of peroxide catalyst);
* Peroxide-catalytic HCR can resist the inhibition of sulfur, Amine, metal and other pollutants.
, Processing silicone rubber near other types of organic and inorganic rubber;
* Parts can be easily manufactured by injection, compression or transfer molding technology or extrusion into the appropriate spoon media;
* High altitude erosion leads to high production of parts for each printing machine;
* High versatility allowing HCR to cure under pressure (
Like in a hot mold)
Or no pressure (
For example, in a hot air tunnel, in a salt bath, or through UV or radiation)
: * The ability to mix high and low second degree rubber to predictable intermediate second degree rubber;
* Use standard rubber forming equipment.
Some of the shortcomings related to dealing with hcr include: * This is labor intensive.
The mixing of HCR compounds requires multiple conditions in order to prepare rubber of a certain shape in order to introduce a processing machine.
In addition, the removal of the cured flash may require post-production processing;
* Possible contamination at different stages of mixing and pre-forming;
* Waste generated by Flash, gate and large gate: * relatively slow curing results in a long curing time: * parts tolerances are not always very accurate and reproducible;
And * may need post-
Curing finished parts for removal of catalyst-
Product or get the best performance.
Up to now, two kinds of hot curing liquid silicone rubber have been supplied
Components A and B, systems that must be mixed before forming and consolidating parts.
These systems contain catalysts mixed to the side, usually platinum compounds.
Contains cross in B sidenormally
A connecting agent, usually hydrogen.
Functional silicone.
The curing system provides fast curing, high strength and tear-resistant silicone rubber for various applications.
Including food contact, medical care, personal care, cars and many other aspects.
Compared with HCR, the advantages of liquid silicone rubber molding are well documented.
Due to its unique advantages, LSR rapidly replaces crs in many molding applications, thus greatly saving resources.
Some ideal features of LSR molding include: * low viscosity of Rapid mold filling even at low injection pressure (ref. 2)
* Very short cycle times: * Excellent physical performance: * easy to automate to achieve maximum productivity while reducing labor utilization and cost: * low likelihood of contamination: * materials can be used without additional processing (
Except for the mixing of A and B components);
* No post-treatment is usually required to remove-
Product ofcuratives;
* Accurate and consistent tolerances can be achieved; and* flash-
Free molding reduces waste by up to 99% compared to HCR.
It also allows automatic inspection and \"packaging\"at-
Press \"ability.
Some inherent disadvantages of the two currently commercialized products
The component LSR system includes: * injection-mold a two-
Components LSR, components A, and B must be fixed in proportion to specific requirements (
1: 1 or 10: 1)
Soon thereafter, hot molds must be introduced and cured. Off-
Ratio is the main problem of dealing with two-component LSR.
* An expensive and complex pumping and metering system is needed to keep the double-
Partial liquid injection system.
* If the mixed ingredients must be stored at any time, it is recommended to store them in cold storage to prevent premature cure.
Thorough cleaning of refrigerated machine parts or removal of machine parts may also be necessary to prevent the mixing material from curing in the nozzle of the screw or syringe of the static mixer.
* Continuous cooling of the syringe may be required to prevent the material from curing and clogging the nozzle within the head of the syringe.
* During extended shutdown, it may be necessary to clean the machine with only one side, which again results in unbalanced use of side A and Side B. One-
Highly innovative components LSRA-
A component liquid silicone rubber combining the advantages of liquid silicone rubber with the advantages of high consistency rubber is introduced.
As Paul Kehl disclosed (ref. 3)
New Laur Silicone-
Component liquid silicone rubber provides viscosity, physical properties, thermal stability, compression permanent deformation, electrical and other properties comparable to standard heatcured,two-
Some liquid silicone rubber. However, one-
Component LSR goes further.
It is not only available as a single component, but also fully composite and ready at any timeto-
Using the product, the pan life at room temperature is more than one year.
In addition, it needs a simpler clock-in system to operate.
By eliminating the need to precisely mix equal parts of components A and B,
The Assembly LSR can introduce a curing cavity using a pumping system as simple as a half box.
LSR molding machine with special design is not required.
Anygood HCR press can be easily converted to run one-component LSR.
The physical properties of one-component LS-
The 7010 series is shown in Table 1.
The flow properties of one-
Component LSR and two of the three available-
The part LSRs is shown in Figure 1.
The multi-drug resistant 2000 thermometer can be used to display two-
Curing profile ratio of part LSRs-component LSR. The two-
Some liquids also show a ratio of 1-
Component products.
However, the longer it takes to bake-
The component LSR can fill large complex molds without significantly sacrificing the curing cycle time. [
Figure 1 slightly]The one-
The component liquid system is thermal stable for storage and transportation.
Figure 2 shows a Storage Stability of up to one year at room temperature with no curing flow loss. [
Figure 2:
We have already proved
The component LSR can be run on the injection molding machine designed to handle the LSR (ref. 4).
Because a long life,
Complete composite and coloring materials using a single LSR pump, no need to use a mixer.
Other work shows that the HCR compression molding application can use one-component LSR.
For example, an application uses a pressure tank to deliver a completely composite material to a standard HCR compression mold with minor modifications.
The processing time is reduced by 70%, and the waste is reduced by more than 99% (ref. 5).
Whether the material is injection molding or compression molding, the performance of the LSR is shown to remain relatively unchanged (ref. 6).
1-injection molding
By reducing the burning time of the material, the component LSR can be accelerated.
Table 2 and Figure 3 show that the thatch time decreases as the preheating temperature increases from [degrees]C to 130[degrees]C. [
Figure 3 slightly]
Homogeneous and non-homogeneous
The concept of different durometer mixes of homogeneous hybrid HCR to obtain predictable durometer is well known (ref. 7).
Although this can also be done with two-
Component LSR, which is rarely done due to the complexity involved.
Introduction of 1-
The component LSR makes this mixture more practical and economical (ref. 8). One-
The component liquid silicone rubber provides complete packaging and preparation for use.
Therefore, the durometer of the incoming material (s)
Well documented.
Therefore, it is feasible to mix these materials into predictable durometer in a manner similar to HCRs mixing.
A current pumping system with precise metering capability should provide the proportional control required to easily mix high and low duple meters into intermediate meters.
Table 3 shows the results that can be achieved by mixing a low and a high degree metercomponent LSR.
Except for the uniform mixture, non-
Uniform mixing of different colors-
The component LSR can be used for significant effects.
HCR commercial products using these types of blendshave have been on the market for many years.
However, using two
The part lsr that makes multi-color molded parts is not known.
The equipment required to achieve this will vary depending on the manufacturing method used.
The simple compression molding technology has been successfully demonstrated in Laur Silicone, in which the weight of various colors is minimized and then introduced into the mold cavity and solidified (ref. 8).
It is also entirely feasible to use standard LSR injectionsForming Machine.
The system can use a very short or no static mixer and inject two (or more)
In the case of little mixing, the color enters the mold cavity.
In order to achieve more color division, a feed system that allows pulses of two materials can be considered.
Because each component is completely catalytic, there is no need to mix evenly to achieve full curing of each color.
Figure 4 shows that you can use non-
Uniform color mixing. [
Figure 4 slightly]Non-
The uniform mixing of different durometer materials can also have a great effect, especially in the drum industry.
Rollers with different colors and/or hardness can be used to teach unusual textures and color patterns to film, laminate, paper, printing and other roller applications.
The possibilities are infinite, and the imagination of only one person is limited. ConclusionOne-
Component liquid silicone rubber allows manufacturers to overcome many shortcomings related to high consistency rubber by combining the best functions of HCR and LSR.
According to the parts and mold configuration, the processing time is reduced by 70% and the waste is reduced by more than 99%. Rash-
Free value-added, almost unique to both
Component LSR, via one-component LSR.
No flash molding eliminates later demand
Manufacturing operations such as low temperature deflating or stamping and allowing packaging under pressure. One-
The component liquid silicone rubber provides the manufacturer with extreme versatility, which can realize short-time operation and fully automatic, high-volume production. References(1. )
Paul Cole and Daniel T.
\"Next generation liquid (2. )
LSR injection mold design principles, Rubber World, December 2003. (3. )
Paul Kehl, \"heat cured part of liquid silicone rubber,\" International silicone conference, May 2004. (4. )
Rubber and plastic news, November 1, 2004. (5. )
Paul Kehl, \"part of liquid silicone in traditional high consistency Silicone Applications\", International silicone conference, April 2005. (6. )James S.
Matthew J Curtis
William D. GuoanInman, Jr. , andJanice D.
Worden, here comes the way, \"liquid injection molding and
Compression molding: Impact on mechanical properties of LSR, \"Rubber World, January 2005. (7. )
Dow 1979 Index: \"silicone rubber products for Silastic NPC 40 and 80 . \". (8. )Daniel T.
\"Homogeneous and non-homogeneous\"
International silicone conference April 2005.
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