No chemical foaming agent or the production of silicone rubber sponge VOC new technologies

Silicone rubber sponge with the requirements for low-temperature flexibility, heat resistance, the resistance of UV, ozone resistance and good electrical insulation properties of occasions. In addition, sponge rubber has also lightweight, thermal insulation and damping characteristics. Now even more intense market competition, the product of the higher requirements, and dense rubber material, silicone rubber sponge because of its density, you can save the use of building materials in order to reduce production costs. Traditional silicon rubber material in the production of sponge rubber by adding chemical foaming agent, curing process, the high temperature decomposition of blowing agents, have a bubble, bubble wrapped in foam rubber in the form of the hole. These traditional foam may have a toxic by-products.

Has now developed a new type of silicone rubber closed-cell foam technology, can be used to replace the traditional reactive chemical blowing agents and volatile organic material (voc) as a foam sponge material processing technology. The new technology uses water as a sponge foam to form a homogeneous structure made of sponge hole, which can be used for food contact with the occasion. New technology sponge performance features are:

(1) back to the good flexibility;

(2) small compression permanent deformation;

(3) to reduce the production of sponge in the process of environmental control;

(4) reduced the requirements for ventilation systems;

(5) no bad smell;

(6) easily molded and extrusion;

(7) surface smooth, uniform;

(8) can be used for food contact with the occasion.

To join in the rubber additives or modifiers can enhance the performance of sponge products.

This article describes the advantages of the technology, performance, as well as the characteristics of Silastic sponge rubber processors and end-user benefits. Sponge rubber may be opening a can of obturator. Pore structure by opening up regional connectivity in the form of (opening) or decentralized structure of a single hole sponge decision. The use of silicone rubber foam can be made of the structure of opening, can also be made of closed-cell structure. This is the heat blowing agent after the formation of air bubbles and pore structure, also into the same reaction so that the rubber vulcanization cross-linked.

It was an overview of the performance of porous Cavernous and cost advantages. In addition to the low-pressure sealing, shape, density of small, light weight, the use of silicone rubber sponge has a wide temperature range (9, -60 ℃ to 250 ℃ under long-term, short-term can be 400 "C). And other rubber Sponge compared to its operating temperature range is very wide. Traditionally, the use of silicone rubber sponge peroxide curing systems and foam production, which will release some of the toxic foaming agent by-products. In some cases, can produce food-grade The silicone rubber sponge, these materials will be restrictions on the existence of technology and poor performance, including poor compression permanent deformation and high density.

New technologies with platinum sponge silicone rubber vulcanization (plus sulfide), blowing agent for water. This new technology can have a uniform pore structure, unscented sponge, the surface of the product uniformity, stability and processing conditions.

1 application

Silicone rubber sponge for a number of occasions. There are commonly used in the field of sealing gasket of the car, office equipment (copiers, printers and fax machines) of the cot. Food security requires access to material goods, including dishwasher and oven sealed with rice lunch box sealed. Silicone rubber sponge for the following occasions: solid rubber seal or with too much power and can not be used; low-density sponge rubber to reduce the cost of materials; need insulation, sponge rubber seals and irregular surfaces, including insulation materials, Sponge mats, foam board, sealing sponge, sponge rubber sponge roll out and profiles.

2 sponge technique

Traditionally, the silicone rubber sponge is to join the foam rubber chemical rubber production. In the heat of the rubber vulcanization process of decomposition of blowing agents, the release of gases (nitrogen is the most common) in the cross-linking rubber in the process of forming the cell. Peroxide curing high-viscosity silicone rubber sponge often used 2,2 - azo-bis-isobutyronitrile (AIBN) as the nitrogen produced chemical blowing agent. Although uniformity and size of the hole, the technology generated by the structure of the sponge is satisfactory, but its main drawback is that will produce toxic by-products harmful to the environment tetracarboxylic butyrate nitrile II. In the rubber industry, people have been identified

This is an insight into the use of silicone rubber sponge important constraints, the need for a non-toxic in favor of environmentally friendly products. There are also low toxicity of the chemical foaming agent. V-nitroso second four-methylene (DNPT) and Azodicarbonamide (ADCA) are two low toxicity of foam, but they form a pore structure of the poor, and the physical properties of sponges Nor stability.

Recently, there have been reports of a manufacturer with a ceramic or organic material made of hollow fiber manufacturing technology of silicon rubber sponge. There is also a manufacturer of flexible coverage with a micro-pore structure made of spherical. However, Dow Corning's technology is based on sponge rubber-based silicone rubber. The new technology of water as a blowing agent, rather than chemical-based foam. In addition, the system uses a proprietary silicone rubber technology, contribute to the formation of water bubbles FAW, and eventually form a uniform pore structure of the rules. Heating, scattered in the silicone rubber matrix of water bubbles to form a uniform pore structure.

The new technology allows the use of temperature change in processing conditions to achieve an ideal expansion characteristics. Figure 1 show that the characteristics can be seen, curing / foam from 200 ℃ temperature rose to 250 ℃ lead to lower density and hardness of Asker.

The use of new technology can change the pore structure to a different volume expansion. So manufacturers can take advantage of curing / density foam to control the temperature. Figure 2 (slightly) compared with a new silicone rubber sponge technology and the traditional use of chemical foam sponge technology. New technology has a thin sponge rubber decentralized structure of the hole.

3 test data

New technology sponge rubber 3 components, which are HBES5000 sponge base, AMS-5000 curing agent and sponge AMS-5001 sponge surface modifier. Manufacturers the flexibility to choose the system can make use of these materials on their own mix of three materials can also be purchased directly from the Dow Corning rubber products. 3 kinds of materials which can be used alone, but also with other with the use of silicone rubber, the production of different density and different deformation of the plastic foam. In this way, factory production control formula is simple and flexible processing, production can meet the needs of different users a wide variety of sponge products.

Now a variety of industry norms for the classification and control of flexible foam products. This article on the new sponge material was tested, and several data and industrial regulate the widespread use of the data were compared to show that the new system with a sponge rubber processing industry to meet the common demands of flexibility. Table 1 Overview of the column can assess the effectiveness of this new silicone rubber sponge technology industry norms.

Table 2 lists the details of this new technology sponge test results with industry norms in front of the item compared. Table 3 lists the sponge rubber formula.

A formula is made up of three components of the system into line with; formula B is made up of three components of the system were 12.5 and dimethyl silicone rubber with material from (Shore A hardness of 70); formula consists of three C 25-component systems and dimethyl silicone rubber composition (Shore A hardness of 70).

After the samples out of sponges in the next 240 ℃ HTV 10min, and then in the 200 ℃ under the curing stage. The results show that for the simple formula can be adjusted so that the deformation of the norms to achieve the target. In addition, the front-density foam discussed with the sulfide / foam temperature, testing shows that the deformation can also be processed to regulate the temperature. This is possible because the new system used in addition to curing systems in a wide temperature range of vulcanized rubber materials. Therefore, through a simple formula to adjust the temperature and process control, manufacturers use Silastic sponge system to meet the requirements of a variety of sponges. Curing systems and water are tasteless foam, foam from a small hole and uniform, smooth surface is not tacky. 2 proper curing, the new sponge technique can be used for food-grade and low deformation (25 and 50 deformation) of the applications.

4 sponge processing

4.1 out

Processing standards can be used out of silicone rubber materials and products out of the sulfide processing equipment to the new technology sponge. At the end of the screw of the rubber temperature should be 25 ℃ ~ 50. C, so the recommendation to take appropriate cooling. Extrusion type should reflect the shape of the silicone rubber sponge material expansion of the line, with solid materials, inflation factor of 1.65 to 1.45 (as the curing conditions, expansion of 3.2 to 4.4 times).

Shape-based counterparts, need to be adjusted to compensate for:

(1) of solid material expansion of the type I (Figure 3);

(2) Corner area, as the heat transfer here soon, the expansion rate over a small part of the profile in a straight line (as I type on the convex surface profile when out for the face, see Figure 4).

Profile extrusion speed depends on the shape of the equipment as well as the processing capacity (the length of the channel sulfide and heat transfer efficiency).

4.2 vulcanization

Curing temperature depends largely on the use of heating equipment. The new technology sponge curing temperature than the traditional chemical foam sponge slightly higher. Curing temperature is higher the lower the density of the sponge. Curing temperature of the entrance channel should be higher than 210 C, this process can be a good sponge. Under the best conditions to profile the size, shape, thickness and curing the oven to determine the number and length.

4.3 molded sponge

Will be forming a good pre-blank plastic into molds, dies, we must leave enough room so that the expansion of the rubber, and fill the mold good shape. General measured by the test can be completely filled cavity in advance of the amount of plastic molding. Molded foam from the module density by mold shape. Recommended for die temperature 200 ℃ ~ 250 ℃, the typical curing time for each mm thick 60s.

New processing Sponge technology has advantages: molding can be used and the process extrusion processing; sulfide addition is beneficial to the environment; the use of non-toxic foam to reduce the environmental pollution and damage to the health of their employees.

5 Conclusion

The new technology silicone rubber sponge in the non-use of chemical blowing agents, so it will not produce harmful by-product of decomposition. Water as a foaming agent, falsely claiming to vulcanized rubber vulcanization system profiles. Sponge technology has the following times:

(1) for contact with food occasions;

(2) in the process no smell;

(3) processing of ventilation do not ask for much;

(4) sponge fine and uniform pore structure;

(5) surface is not tacky;

(6) through a simple formula to adjust the temperature or processing will be able to control the characteristics of the sponge.

The article set out to achieve the flexibility and deformation, density and compression permanent deformation data processors to meet the major industrial applications for silicone rubber sponge. Silastic sponge is a 3-component system, and its processing flexibility, manufacturers can choose their own with the rubber mixture can also be directly provided by the company Dow Corning rubber products.