High-hardness microcellular foaming silicone rubber as well as preparation method and application thereof

Abstract

The invention provides high-hardness microcellular foaming silicone rubber as well as a preparation method and application thereof. Relates to the field of organosilicon foaming materials. The liquid rubber comprises the following raw materials in parts by weight: 100 parts of liquid silicone rubber, 1-35 parts of filler, 0.2-2 parts of a release agent, 1-10 parts of a plasticizer, 1-10 parts of a foaming agent, 0.02-0.2 part of a vulcanizing aid and 1-20 parts of a vulcanizing agent. The low-temperature foaming agent and the high-temperature foaming agent are used at the same time, the low-temperature foaming agent is used for foaming at a low temperature, the high-temperature foaming agent is used for foaming at a high temperature, the silicone rubber system can firstly foam at the low temperature and then foam at the high temperature, and the low-temperature foaming agent and the high-temperature foaming agent cooperate with each other. The microcellular foaming silicone rubber prepared by the preparation method disclosed by the invention has the characteristics of good rebound resilience, high hardness and high strength and has good supporting and sealing effects by adding the microcellular foaming agent into the microcellular foaming silicone rubber, and the microcellular foaming silicone rubber with uniform and fine foam holes is formed through mutual cooperation of the microcellular foaming agent and other components in a silicone rubber system.

Description

Technical Field

[0001] The invention relates to the field of organic silicon foam materials, and in particular to a high-hardness microporous foamed silicone rubber, a preparation method and an application thereof. Background Art

[0002] Foamed silicone rubber is a porous polymer elastomer that has been foamed. Due to its special structure, silicone rubber itself has good high and low temperature resistance, weather resistance and physiological inertness, while foamed materials have the characteristics of light weight, good cushioning, shock absorption, damping, sound insulation and thermal insulation. Therefore, foamed silicone rubber has the advantages of both ordinary silicone rubber and foamed materials.

[0003] Due to the above characteristics of foamed silicone rubber, it is widely used in the fields of national defense, military industry and daily life, and is especially suitable for preparing super spacers of insulating glass. However, in the prior art, the foamed silicone rubber has an uneven pore structure and large pores, resulting in poor mechanical properties and low hardness. Usually, its Shore C hardness is only 20 to 30 degrees. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention aims to provide a high-hardness microporous foamed silicone rubber and a preparation method thereof.

[0005] One of the purposes of the present invention is to provide a high-hardness microporous foamed silicone rubber, wherein the high-hardness microporous foamed silicone rubber comprises the following raw materials in parts by weight:

[0006]

[0007] The foaming agent comprises a first foaming agent and a second foaming agent, the first foaming agent is a low-temperature foaming agent, and the second foaming agent is a high-temperature foaming agent.

[0008] Preferably, the first foaming agent includes one or more of NaHCO3 and hydroxy silicone oil; the second foaming agent includes one or more of foaming agent H, AC, OBSH, n-propanol or distilled water.

[0009] Preferably, the mass ratio of the first foaming agent to the second foaming agent is 1 to 2:1, more preferably 1.5:1.

[0010] Preferably, the first foaming agent includes hydroxy silicone oil, and the second foaming agent includes OBSH.

[0011] Preferably, the filler includes one or more of CNS, graphene, carbon black, conductive carbon black, white carbon black, diatomaceous earth, silica powder, mica, calcium carbonate, barium sulfate, molecular sieve or tetrafluoroethylene powder.

[0012] Preferably, the filler comprises CNS and molecular sieve.

[0013] Preferably, the mass ratio of CNS to molecular sieve is 1:25 to 65, preferably 1:32.5.

[0014] Preferably, the release agent comprises one or more of paraffin, sodium stearate, clay or polyethylene glycol.

[0015] Preferably, the release agent comprises sodium stearate.

[0016] Preferably, the vulcanizing agent includes one or more of ethyl orthosilicate, hydrogen-containing silicone oil, bis(2,4-dimethylsiloxane), bis(2,5-dimethylsiloxane) or dicumyl peroxide.

[0017] Preferably, the vulcanizing agent includes hydrogen-containing silicone oil.

[0018] Preferably, the vulcanization aid includes one or more of triallyl isocyanurate, dibutyltin dilaurate, a platinum catalyst, 4,4'-dimorpholine disulfide, tetramethylthiuram disulfide or N,N'-m-phenylene bismaleimide.

[0019] Preferably, the vulcanization aid comprises a platinum catalyst.

[0020] The second object of the present invention is to provide a method for preparing high-hardness microporous foamed silicone rubber, the preparation method comprising:

[0021] After all the raw materials are evenly mixed, they are calendered to obtain a rubber sheet, and then the rubber sheet is subjected to primary vulcanization and secondary vulcanization;

[0022] The one-stage vulcanization includes a front-stage drying tunnel and a rear-stage drying tunnel, the front-stage drying tunnel temperature is 50-110°C, the residence time is 5-30 minutes, and the rear-stage drying tunnel temperature is 110-200°C, and the residence time is 5-30 minutes;

[0023] The second stage vulcanization temperature is 120-220° C., and the vulcanization time is 0.5-6 hours.

[0024] Preferably, the preparation method comprises:

[0025] A. Add liquid silicone rubber, filler, release agent and plasticizer into a kneader in sequence and mix them evenly to obtain a standby rubber;

[0026] B divides the spare rubber into two parts, adds foaming agent and vulcanizing agent to the first part of the spare rubber, mixes them well, and obtains A rubber;

[0027] Add the vulcanizing agent to the second portion of the standby rubber C and mix well to obtain rubber B;

[0028] D. Mix glue a and glue b evenly, and calender them using a calender to obtain a rubber sheet.

[0029] Preferably, in step A, the mixing temperature is 120-200° C., and the mixing time is 1-6 hours.

[0030] The third object of the present invention is to provide an application of the high-hardness microporous foamed silicone rubber as described above, characterized in that the high-hardness microporous foamed silicone rubber is used to prepare super spacers for insulating glass.

[0031] The beneficial effects of the present invention include:

[0032] The present invention uses a low-temperature foaming agent and a high-temperature foaming agent at the same time, the low-temperature foaming agent is used for foaming at low temperatures, and the high-temperature foaming agent is used for foaming at high temperatures. The silicone rubber system can first be foamed at low temperatures and then at high temperatures. The low-temperature foaming agent and the high-temperature foaming agent cooperate with each other and cooperate with other components in the silicone rubber system to form microporous foamed silicone rubber with uniform and fine pores. The microporous foamed silicone rubber has the characteristics of good resilience, high hardness, high strength, and good support and sealing effects. The high-hardness microporous foamed silicone rubber provided by the present invention has a Shao C hardness of up to 81 degrees. DETAILED DESCRIPTION

[0033] According to the first aspect of the present invention, a high-hardness microporous foamed silicone rubber is provided, and the high-hardness microporous foamed silicone rubber comprises the following raw materials in parts by weight.

[0034]

[0035] The foaming agent comprises a first foaming agent and a second foaming agent, the first foaming agent is a low-temperature foaming agent, and the second foaming agent is a high-temperature foaming agent.

[0036] In the present invention, first, at low temperature, the low-temperature foaming agent foams rapidly and forms gas-phase nuclei inside the silicone rubber. Since the silicone rubber has not yet undergone a cross-linking reaction, the viscosity of the silicone rubber system is relatively small, and the formed tiny gas nuclei are uniformly dispersed in the silicone rubber system. Then, at high temperature, the high-temperature foaming agent foams rapidly to form uniform pores around the tiny gas nuclei. At the same time, the silicone rubber undergoes a cross-linking reaction to form a three-dimensional network structure. The viscosity of the system increases, and the resistance to pore growth increases, which can limit the pore size from being too large.

[0037] The present invention controls the foaming of the silicone rubber system by using a low-temperature foaming agent and a high-temperature foaming agent, and cooperates with other components in the silicone rubber system to form a microporous foamed silicone rubber with uniform and fine pores. The microporous foamed silicone rubber has the characteristics of good resilience, high hardness, high strength, and good supporting and sealing effects.

[0038] In the present invention, the weight of the foaming agent is, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts.

[0039] In the present invention, the filler can enhance the mechanical properties and physical properties of the rubber. The weight of the filler is, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts or 35 parts.

[0040] In the present invention, the release agent is used to smoothly separate the cured product from the mold. The weight of the release agent is, for example, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts or 2.0 parts.

[0041] In the present invention, the plasticizer can reduce the force between rubber molecules, enhance the plasticity and fluidity of rubber, and facilitate the molding operations such as calendering and extrusion. The weight of the plasticizer is, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0042] In the present invention, the vulcanization accelerator can greatly promote the reaction between the rubber and the vulcanizing agent, accelerate the vulcanization reaction speed, shorten the vulcanization time, reduce the vulcanization reaction temperature, reduce the amount of vulcanizing agent, and increase the mechanical properties of the rubber. The weight of the vulcanization accelerator is, for example, 0.02 parts, 0.04 parts, 0.06 parts, 0.08 parts, 0.10 parts, 0.12 parts, 0.14 parts, 0.16 parts, 0.18 parts or 0.2 parts.

[0043] In the present invention, the vulcanizing agent changes the rubber from a linear macromolecular chain to a three-dimensional network structure through chemical crosslinking, thereby changing the performance from plasticity to elasticity, thus having practical value. The weight of the vulcanizing agent is, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts.

[0044] In a preferred embodiment of the present invention, the first foaming agent includes one or more of NaHCO3 and hydroxy silicone oil; the second foaming agent includes one or more of foaming agent H, AC, OBSH, n-propanol or distilled water.

[0045] Preferably, the mass ratio of the first foaming agent to the second foaming agent is 1 to 2:1, preferably 1.5:1.

[0046] Preferably, the mass ratio of the first foaming agent to the second foaming agent is, for example, 1:1, 1.5:1 and 2:1.

[0047] In the present invention, the first foaming agent is, for example, NaHCO3, hydroxy silicone oil, or a combination of NaHCO3 and hydroxy silicone oil. The second foaming agent is, for example, foaming agent H, AC, OBSH, n-propanol, distilled water, foaming agent H and AC, foaming agent H and OBSH, OBSH and AC, or a combination of AC, OBSH and n-propanol.

[0048] Preferably, the first foaming agent includes hydroxy silicone oil; and the second foaming agent includes OBSH.

[0049] In a preferred embodiment of the present invention, the filler includes one or more of CNS, graphene, carbon black, conductive carbon black, white carbon black, diatomaceous earth, silica powder, mica, calcium carbonate, barium sulfate, molecular sieve or tetrafluoroethylene powder.

[0050] In the present invention, the filler is, for example, CNS, graphene, carbon black, conductive carbon black, white carbon black, diatomaceous earth, silica powder, mica, calcium carbonate, barium sulfate, molecular sieve, tetrafluoroethylene powder, CNS and molecular sieve, CNS, white carbon black and molecular sieve, or a combination of CNS, graphene and molecular sieve.

[0051] Preferably, the filler comprises CNS and molecular sieve.

[0052] In the present invention, CNS is a unique network structure formed by cross-linking branched carbon nanotubes. During the dispersion process, under the action of low shear force, CNS particles can be broken into branched carbon nanostructures in the matrix, which can be evenly dispersed in the silicone rubber system. The branched carbon nanotube structure is more conducive to enhancing the mechanical properties of the silicone rubber system. The synergistic effect of CNS and molecular sieve is more conducive to controlling the viscosity of the silicone rubber system, making the pores more evenly dispersed, reducing the pore size, and providing a good water vapor adsorption effect.

[0053] Preferably, the mass ratio of CNS to molecular sieve is 1:25 to 65, preferably 1:32.5.

[0054] In the present invention, the mass ratio of CNS to molecular sieve is, for example, 1:25, 1:30, 1:32.5, 1:43.3 or 1:65.

[0055] In a preferred embodiment of the present invention, the release agent includes one or more of paraffin, sodium stearate, clay or polyethylene glycol.

[0056] In the present invention, the release agent is, for example, paraffin wax, sodium stearate, clay, polyethylene glycol, paraffin wax and sodium stearate, paraffin wax and clay, or a combination of paraffin wax and polyethylene glycol.

[0057] Preferably, the release agent comprises sodium stearate.

[0058] In a preferred embodiment of the present invention, the vulcanization aid includes one or more of triallyl isocyanurate, dibutyltin dilaurate, a platinum catalyst, 4,4'-dimorpholine disulfide, tetramethylthiuram disulfide or N,N'-m-phenylene bismaleimide.

[0059] In the present invention, the vulcanization aid is, for example, triallyl isocyanurate, dibutyltin dilaurate, a platinum catalyst, 4,4'-dimorpholine disulfide, tetramethylthiuram disulfide, N,N'-m-phenylene bismaleimide, triallyl isocyanurate and dibutyltin dilaurate, a platinum catalyst and 4,4'-dimorpholine disulfide, or a combination of a platinum catalyst and tetramethylthiuram disulfide.

[0060] Preferably, the vulcanization aid comprises a platinum catalyst.

[0061] In a preferred embodiment of the present invention, the vulcanizing agent includes one or more of tetraethyl orthosilicate, hydrogen-containing silicone oil, bis(2,4-dimethylsiloxane), bis(2,5-dimethylsiloxane) or dicumyl peroxide.

[0062] In the present invention, the vulcanizing agent is, for example, tetraethyl orthosilicate, hydrogen-containing silicone oil, diisopropyl dioxane, diisopropyl dioxane, dicumyl peroxide, a combination of tetraethyl orthosilicate and hydrogen-containing silicone oil, hydrogen-containing silicone oil and diisopropyl dioxane, or diisopropyl dioxane and dicumyl peroxide.

[0063] Preferably, the vulcanizing agent includes hydrogen-containing silicone oil.

[0064] According to a second aspect of the present invention, a method for preparing a high-hardness microporous foamed silicone rubber is provided, the preparation method comprising:

[0065] After all the raw materials are evenly mixed, they are calendered to obtain a rubber sheet, and then the rubber sheet is subjected to primary vulcanization and secondary vulcanization;

[0066] The one-stage vulcanization includes a front-stage drying tunnel and a rear-stage drying tunnel, the front-stage drying tunnel temperature is 50-110°C, the residence time is 5-30 minutes, and the rear-stage drying tunnel temperature is 110-200°C, and the residence time is 5-30 minutes;

[0067] The second stage vulcanization temperature is 120-220° C., and the vulcanization time is 0.5-6 hours.

[0068] In the present invention, the silicone rubber system undergoes foaming and cross-linking reactions in a first stage of vulcanization. In the front stage of the drying oven, the first foaming agent in the silicone rubber system undergoes foaming. By adjusting the temperature of the front stage of the drying oven, the foaming rate of the first foaming agent can be controlled, thereby forming a more uniform gas core. In the rear stage of the drying oven, the second foaming agent in the silicone rubber foams and undergoes a cross-linking reaction at the same time. By controlling the temperature of the rear stage of the drying oven, the foaming rate of the second foaming agent and the rate of the cross-linking reaction can be controlled, thereby forming a foamed silicone rubber with uniform pores and a smaller pore size. The silicone rubber system undergoes high-temperature vulcanization and shaping in the second stage of vulcanization.

[0069] In the present invention, the temperature of the front drying oven is, for example, 50°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C or 110°C. The temperature of the rear drying oven is, for example, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C. The temperature of the second stage vulcanization is, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C or 220°C.

[0070] Preferably, the preparation method comprises:

[0071] A. Add liquid silicone rubber, filler, release agent and plasticizer into a kneader in sequence and mix them evenly to obtain a standby rubber;

[0072] B divides the spare rubber into two parts, adds foaming agent and vulcanizing agent to the first part of the spare rubber, mixes them well, and obtains A rubber;

[0073] Add the vulcanizing agent to the second portion of the standby rubber C and mix well to obtain rubber B;

[0074] D. Mix the rubber a and rubber b evenly, and use a calender to calender to obtain a rubber sheet;

[0075] Preferably, in step A, the mixing temperature is 120-200° C., and the mixing time is 1-6 hours.

[0076] The third object of the present invention is to provide an application of the high-hardness microporous foamed silicone rubber as described above, characterized in that the high-hardness microporous foamed silicone rubber is used in the insulating glass super spacer industry.

[0077] Example

[0078] The present invention provides 15 embodiments, and Table 1 shows the raw material ratios of embodiments 1 to 15 and comparative examples 1 and 2. The mold release agent used in embodiments 1 to 15 and 1 and 2 is sodium stearate, which is 1 part by weight; the plasticizer is dimethyl silicone oil, which is 3 parts by weight; the vulcanizing agent is hydrogen-containing silicone oil, which is 10 parts by weight; and the vulcanization aid is a platinum catalyst, which is 0.1 parts by weight.

[0079] The other raw material proportions of Examples 1-15 and Comparative Examples 1-2 are shown in Table 1.

[0080] Table 1 Raw material ratios of Examples 1-15 and Comparative Examples 1-2

[0081]

[0082] The specific preparation method is:

[0083] Liquid silicone rubber, filler, release agent and plasticizer are poured into a kneader in sequence, and mixed at 150°C for 6 hours to obtain a standby rubber; the standby rubber is divided into two parts, a foaming agent and a vulcanizing agent are added to the first standby rubber, and mixed to obtain a rubber; a vulcanizing agent is added to the second standby rubber, and mixed to obtain b rubber; the a rubber and the b rubber are mixed evenly, and calendered by a calender to obtain a rubber sheet; in Examples 1 to 15, the calendered rubber sheet first enters the low-temperature part of the front-stage drying channel at 80°C, with a residence time of 20 minutes, and then enters the high-temperature part of the rear-stage drying channel at 180°C, with a residence time of 20 minutes; a calendered foamed rubber sheet is obtained; Comparative Example 1 only enters the low-temperature part of the front-stage drying channel at 80°C for 30 minutes; Comparative Example 2 directly enters the high-temperature drying channel at 180°C for 30 minutes.

[0084] The calendered foam rubber sheet is subjected to a two-stage vulcanization process in a drying oven at 200° C., with a secondary vulcanization time of 3 hours, to prepare the microporous foamed liquid silicone rubber strip.

[0085] Performance Testing

[0086] 1. Viscosity test

[0087] The test is carried out in accordance with "GB / T2794-2013 Adhesive Viscosity Determination Single Drum Rotational Viscometer Method".

[0088] 2. Cell diameter

[0089] Measured using a gold image microscope.

[0090] 3. Density

[0091] The test is carried out in accordance with GB / T533-2008 Determination of density of vulcanized rubber or thermoplastic rubber.

[0092] 4. Shore A hardness

[0093] The test is carried out in accordance with GB / T 531.1-2008 Test method for Shore hardness of vulcanized rubber or thermoplastic rubber.

[0094] 5. Shore C hardness

[0095] The test was carried out in accordance with JIS K7312 Physical test methods for thermosetting polyurethane elastomer molded products.

[0096] 6. Water vapor adsorption rate

[0097] Test according to "T / ZBH004-2018 Insulating Glass Sealant".

[0098] Table 2 Test results of microporous foamed liquid silicone rubber strips

[0099]

[0100]

[0101] It should be understood by those skilled in the art that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0102] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-hardness microporous foamed silicone rubber, characterized in that: The high-hardness microporous foamed silicone rubber comprises the following raw materials in parts by weight: The foaming agent comprises a first foaming agent and a second foaming agent, the first foaming agent is a low-temperature foaming agent, and the second foaming agent is a high-temperature foaming agent.

2. The high-hardness microporous foamed silicone rubber according to claim 1, characterized in that: The first foaming agent includes one or more of NaHCO3 and hydroxy silicone oil; the second foaming agent includes one or more of foaming agent H, AC, OBSH, n-propanol or distilled water; Preferably, the mass ratio of the first foaming agent to the second foaming agent is 1 to 2:1, preferably 1.5:1; Preferably, the first foaming agent comprises hydroxy silicone oil; Preferably, the second blowing agent comprises OBSH.

3. The high-hardness microporous foamed silicone rubber according to claim 1, characterized in that: The filler includes one or more of CNS, graphene, carbon black, conductive carbon black, white carbon black, diatomaceous earth, silica powder, mica, calcium carbonate, barium sulfate, molecular sieve or tetrafluoroethylene powder; Preferably, the filler comprises CNS and molecular sieve; Preferably, the mass ratio of CNS to molecular sieve is 1:25 to 65, preferably 1:32.

5.

4. The high-hardness microporous foamed silicone rubber according to claim 1, characterized in that: The release agent includes one or more of paraffin, sodium stearate, clay or polyethylene glycol; Preferably, the release agent comprises sodium stearate.

5. The high-hardness microporous foamed silicone rubber according to claim 1, characterized in that The vulcanizing agent is one or more of ethyl orthosilicate, hydrogen-containing silicone oil, diisopropylbenzene peroxide, diisopropylbenzene peroxide, or diisopropylbenzene peroxide; Preferably, the vulcanizing agent includes hydrogen-containing silicone oil.

6. The high-hardness microporous foamed silicone rubber according to claim 1, characterized in that The vulcanization aid is one or more of triallyl isocyanurate, dibutyltin dilaurate, platinum catalyst, 4,4'-dimorpholine disulfide, tetramethylthiuram disulfide or N,N'-m-phenylene bismaleimide; Preferably, the vulcanization aid comprises a platinum catalyst.

7. The method for preparing the high-hardness microporous foamed silicone rubber according to any one of claims 1 to 6, characterized in that: The preparation method comprises: After all the raw materials are evenly mixed, they are calendered to obtain a rubber sheet, and then the rubber sheet is subjected to primary vulcanization and secondary vulcanization; The one-stage vulcanization includes a front-stage drying tunnel and a rear-stage drying tunnel, the front-stage drying tunnel temperature is 50-110°C, the residence time is 5-30 minutes, and the rear-stage drying tunnel temperature is 110-200°C, and the residence time is 5-30 minutes; The second stage vulcanization temperature is 120-220° C., and the vulcanization time is 0.5-6 hours.

8. The method for preparing high-hardness microporous foamed silicone rubber according to claim 7, characterized in that: The preparation method of the rubber sheet comprises: A. Add liquid silicone rubber, filler, release agent and plasticizer into a kneader in sequence and mix them evenly to obtain a standby rubber; B divides the spare rubber into two parts, adds foaming agent and vulcanizing agent to the first part of the spare rubber, mixes them well, and obtains A rubber; Add the vulcanizing agent to the second portion of the standby rubber C and mix well to obtain rubber B; D. Mix the rubber a and rubber b evenly, and use a calender to calender to obtain a rubber sheet; Preferably, in step A, the mixing temperature is 120-200° C., and the mixing time is 1-6 hours.

9. The method for preparing high-hardness microporous foamed silicone rubber according to claim 7, characterized in that: In the method for preparing the rubber sheet, the mixing temperature in step A is 120-200° C., and the mixing time is 1-6 hours.

10. The use of the high-hardness microporous foamed silicone rubber according to any one of claims 1 to 7, characterized in that: The high-hardness microporous foamed silicone rubber is used for preparing super spacer strips of insulating glass.

Images