Silicic acid preparation

[Detailed Description of the Invention]

The present invention relates to using the hydrophobic precipitation silicic acid obtained from precipitation silicic acid, its manufacturing method, and it as a reinforcement bulking agent for the constituent which can be hardened to an elastomer. A bulking agent is a solid substance which has inorganic various composition in general. the particle is detailed -- it is -- carrying out -- various kinds of forms can be taken by the shape of a big and rough particle, and it is added by chemical industrial output in order to improve fixed character. One publicly known bulking agent is the silica dioxide manufactured by heat treatment, for example, Aerosil, (Aerosil). As for the manufacturing process of the silica dioxide obtained from high temperature processing, since expense starts, it is desirable to instead use it in many points manufactured by the wet chemical method, the silica dioxide, i.e., what is called precipitation silicic acid, of an equivalent value. The materials of hydrophobic precipitation silicic acid by the present invention are precipitation silicic acid characterized with the following physicochemical substance data: [Table]

About the substance which carried out time dryness In the desirable embodiment of precipitation silicic acid, the electric conduction rate in the inside of 4% water dispersion liquid may reach 50 thru/or 300microS. SO₃In a desirable embodiment, a content may reach to 0.03 thru/or 0.2%. Similarly, it is Na of the desirable embodiment of precipitation silicic acid.₂O content may reach to 0.03 thru/or 0.2%. One object of the present invention is characterized according to Then and the following matter with the hydrophobic precipitation silicic acid obtained by the reaction of the above-mentioned precipitation silicic acid: [Table]

About quality [Table]

In the desirable embodiment of hydrophobic precipitation silicic acid by the present invention, loss on drying may reach to 2.5 thru/or 0.0%. The electric conduction rate of hydrophobic precipitation silicic acid by the present invention may reach 50 thru/or 300microS. Water wettability may be 0 thru/or 0.05. The object of the present invention is in charge of manufacturing hydrophobic precipitation silicic acid from the above-mentioned precipitation silicic acid, Precipitation silicic acid is mixed at a rate of a canal-ized agent, 10:0.5 to 10:3 within a mixed device, It is a manufacturing method of the above-mentioned hydrophobic precipitation silicic acid characterized for the output obtained by continuing mixed operation after the end of addition of a canal-ized agent depending on the case by heat-treating for 70 thru/or 130 minutes for 60 thru/or 180 minutes desirable at the temperature of 200 thru/or 400 degreeC. As a mixed device, it is Ullman's "industrial chemistry encyclopedia" (Ullmanns Enzyklopa *die der technischen Chemie), All the publicly known mixers which are indicated to 1st volume the 713rd less than page, the 3rd edition, and the Urban Wundt Schuur published by Rutsuenberuku (Verlag Urban&Schwarzenberg) may be used. As a canal-ized agent, the organic silicon compound reacted to a solid high distribution silica dioxide may be used also in the range of the present invention like the same compound conventionally used for this kind of reaction. A desirable thing is a general formula (R).₃Si)_az (R means the Hydrocarbon residue machine which was replaced depending on the same or difference Noodle univalent case, and/or polymerized among an upper type, a means 1 or 2, and Z is halogen, hydrogen or formula-OH, -OR, -NRX, and -ONR.)₂or it means the basis denoted by -SR, -OOCR, -O-, -N(X)-, or -S-, and R has an above meaning here, respectively and X is hydrogen -- or the same meaning as R -- having -- it is a compound expressed. The examples of such an organic silicon compound are hexamethyl disilazane and trimethylsilane, Trimethylchlorosilane, trimethylethoxysilane, Tori ORGANO silyl mercaptan, For example, trimethylsilyl mercaptan, Tori ORGANO silylacrylate, For example, Vinyl di methyl acetoxysilane, Tori ORGANO silylamine, For example, trimethylsilyl isopropylamine, trimethylsilyl ethyl amine, Dimethylphenyl silyl propylamine and a vinyl dimethylsilyl butylamine, The Tori ORGANO silyl Aminooxy compound, for example, diethylamino Oxy trimethylsilane, and diethylamino oxydi methyl phenylsilane, They are hexamethyl disiloxane, 1 and 3-Divinyl tetramethyl disiloxane, 1 and 3-diphenyl tetramethyl disiloxane, and 1 and 3-diphenyl hexamethyl disilazane. For the example of others of the organic silicon compound which can react with solid high distribution precipitation silicic acid in the range of the present invention, Dimethyldi Chlorosilane, dimethyldi ethoxy Silane, dimethylethoxy Silane, Dimethyldimethoxysilane, diphenyl diethoxysilane, The unit which has vinylmethyldimethoxysilane and octamethylcyclotetrasiloxane, and/or 2 thru/or 12 Shiroki Sun units per molecule, and is located in an end has dimethylpolysiloxane containing the hydroxyl group combined with Si addressed to one piece, respectively. The example of further others of the organic silicon compound which can react with precipitation silicic acid is silicone oil which consists of line organopolysiloxane. The valence of the isolation which has not been combined with oxygen of silicon is CH.₃- C₆H₅- It may be filled by an organic basis or hydrogen. [ like ] In 20 degreeC, good [ of the viscosity ] is carried out 20 thru/or 500 cP 3 thru/or 1000 cP, and To may be 20 thru/or 100cP. The mixture of a different Noodle organic silicon compound can also react with precipitation silicic acid. The organic silicon compound reacted to the precipitation silicic acid divided minutely is used in 5 thru/or 30% of the weight of quantity about the weight of the precipitation silicic acid which should react to each preferably. the present invention -- therefore, a term called the "solid" or the "solid" in combination with the precipitation silicic acid used, Precipitation silicic acid shall mean that not a form but the adsorbed water of silicic acid sol exist as another with the powdered form which the solid air-dried, before being made [ that you are made to contact water depending on the case, and ] to react to an organic silicon compound. However, the term of "having dried [ be / it / under / this / specification / setting ]" instead of the term a "solid" is used. It is an object of the present invention similarly to use hydrophobic silicic acid by the present invention as a reinforcement bulking agent into the constituent on the basis of diorganopolysiloxane which is hardened and can be made into an elastomer. According to the present invention, the above-mentioned hydrophobic precipitation silicic acid can be used for the diorganopolysiloxane elastomer by which heating hardening may be carried out. In the organopolysiloxane elastomer which is made the same in this way and can be hardened in room temperature, it may be preferably used in the constituent for 2 ingredient system printing, or the constituent for 1 ingredient system ceilings. As diorganopolysiloxane, it sets to room temperature (RTV) conventionally, At the temperature (LTV) or high temperature (HTV) raised slightly, it was used as a substrate for the constituent which can be hardened to an organopolysiloxane elastomer or is hardened to it, or all the diorganopolysiloxane which might be used may be used. They are for example, general formulas ZnSi (R)._3-o-O-[Si (R)₂O]_x-Si(R)_3-o-Zn (Among an upper type, R are the same or different from each other.) The Hydrocarbon residue machine which replaced and/or polymerized depending on the univalent case is meant, Z means an alkenyl group, when the constituent which can be hardened at a hydroxyl group, the basis which may be hydrolyzed and/or the atom which may be hydrolyzed, or the temperature raised slightly exists, and n is 1, 2, or 3 -- and x -- at least 1 integer -- it is -- it can express. the inside of the Shiroki Sun chain of the above-mentioned formula -- or -- although not usually expressed in this kind of formula in the Shiroki Sun chain -- the other Shiroki Sun units RSiO which exist only as impurities mostly, for example, a formula_3/2R₃SiO_1/2And SiO_4/2What is expressed with (R has an above meaning here, respectively) may exist as a Diorganosiloxane unit. The quantity of other Shiroki Sun units of these must not exceed 10-mol %. The examples of Hydrocarbon residue machine R are a Alkyl machine, for example, methyl, ethyl, propyl, butyl, hexyl, an octyl machine; alkenyl group, for example, vinyl, an ant roux, an ethyl ant roux, butadienyl machine;, an aryl group, for example, phenyl, and a trill machine. Especially the examples of replaced Hydrocarbon residue machine R are a halogenated hydrocarbon Remaining machine, for example, 3, 3, and 3-truffe Ruol propyl group, Chlor phenyl, Brom trill machine;, and a cyanogen Alkyl machine, for example, beta-cyanogen ethyl group. There are the poly styryl combined with silicon via carbon as an example of Hydrocarbon residue machine R which is not replaced [ the substitution (it can also be called "denaturation" further again) of a polymer or ], polyvinyl acetate, poly acrylate poly methacrylate, and a poly acrylics nitrile group. Most Remaining machines R consist of methyl groups preferably [ since acquisition is easier ] above all at least. Especially other Remaining machines that may exist depending on the case are vinyl and/or a phenyl group. When the constituent hardened to an elastomer in room temperature when it is storage stability and water invades under interception of water especially exists, the basis which may be mostly hydrolyzed as Z is important. In the example of such a basis, it is amino , amide, amino Oxy-, oxime, and alkoxy , alkoxy alkoxy (for example, CH).₃OCH₂CH₂O-, alkenyloxy (for example, H)₂O=(CH₃There are CO-, reed Roxy-, and a phosphate machine. As Z, a reed Roxy machine, especially an acetoxy group are [ that acquisition is especially easier, therefore ] preferred. However, for example, it is formula-ON=C (CH) as Z.₃)(C₂H₅Although expressed, the result which was excellent also in what has an oxime machine [ like ] is brought about. The examples of atom Z which may be hydrolyzed are a halogen atom and a hydrogen atom. The example of alkenyl group Z is a vinyl group especially. Z which is the same or different may be combined with Si atom. As a constituent which can be hardened to an elastomer above all, the constituent which may be applied by pouring or application is advantageous, without using a solvent. Although viscosity of the RTV-diorganopolysiloxane used within the limits of the present invention was carried out, in an intermediary and 25 degreeC, it must not exceed 150000cP in 500000cP, preferably 25 degreeC. So, the value of x must not exceed 40000 preferably. The mixture of different Noodle diorganopolysiloxane can be used. From the bulking agent obtained by the reaction of an organic silicon compound and a silica dioxide by the present invention, it sets to room temperature or the temperature raised slightly by mixing with the substance of further others depending on diorganopolysiloxane and the case, After adding a hardening agent depending on the case, when it is storage stability and water invades under interception of the constituent which may be hardened to an elastomer, especially water, the constituent hardened to an elastomer in room temperature is manufactured. This mixture is arbitrary publicly known methods, and is performed, for example in a mechanical mixture device. It is performed very quickly and easily, and is carried out regardless of an order of addition of a mixed ingredient. the present invention -- therefore, as for the bulking agent used, it is preferred to use it about the whole quantity of the constituent which may be hardened to an elastomer in 5 thru/or 50 % of the weight, preferably 5 thru/or 40% of the weight of quantity. In the case of a HTV-organopolysiloxane elastomer, it can be used to 50 % of the weight. It will be this diorganopolysiloxane if the hydroxyl group combined with Si as each reactant end unit exists in diorganopolysiloxane containing a reactant end unit, In order to harden by a publicly known method in itself, or in order to change into the compound hardened to an elastomer on the basis of addition of additional water by a case with the water contained in the air, it must be made to react to a hardening agent by a publicly known method under existence of a condensation catalyst depending on the case. In the case of a HTV-diorganopolysiloxane elastomer in a suitable advantageous temperature -- the [ for example, / Screw- 2 and 4-dichlorbenzoyl peroxide, benzoyl peroxide, and ] -- the [ 3-butyl par benzoate or ] -- organic peroxide like 3-butyl par acetate can be used. As ORGANO Shiroki Sun of heating hardenability, a part for organic substitution is methyl, ethyl, phenyl, and trifluormethyl phenyl [F.₃CC₆H₄-] or a Trimethylsil methylene machine -- [ (CH)₃)₃SiCH₂- What consists of ], for example, Dimethyl-, Diethyl-, phenylmethyl, The copolymer of phenylethyl, ethyl methyl, Trimethylsil methylene methyl, Trimethylsil methylene ethyl, trifluormethyl phenylmethyl, trifluormethyl phenylethyl Siloxane, or such a compound may be used. These polymers are the amount of limitation and formula RSiO of diphenyl Siloxane-, screw -Trimethylsil methylene Siloxane-, and a Screw- trifluormethyl phenyl Siloxane unit._1.5And R₃Si_0.5Shiroki Sun which has a unit shown by (R expresses the above-mentioned basis here) may also contain. Especially as an example of a hardening agent, it is general formula R._4-tSiZ'_tThere is Silang shown by (Z' means the basis which may be hydrolyzed, and/or the atom which may be hydrolyzed by inside R of an upper type having an above meaning, and t is 3 or 4). The example of the above-mentioned basis Z which may be hydrolyzed, and atom Z which may be hydrolyzed is fully applied also to basis Z' and atomic Z' which may be hydrolyzed which may be hydrolyzed. In the example of Silang shown by the above-mentioned formula, it is methyltriacetoxysilane, Isopropyl triacetoxysilane, isopropoxy poly acetoxysilane, There are vinyltriacetoxysilane, methyl tris diethylamino Xylosilane, methyl tris (- cyclohexylamino)-Silang, methyl tris (- diethyl phosphite)-Silang, and methyl tris (- methyl Ethylke crested ibis SIMM)-Silang. It mixes with those Silang instead of Silang shown by the above-mentioned formula, For example, it has at least three Z-bases or the atoms per molecule, and Pori Shiroki Sun where the valence of the silicon which has not been saturated with a Z'-basis or an atom in that case is saturated by R basis depending on the oxygen atom of Shiroki Sun and the case may also be used. The example in which this kind of hardening agent was known best is about 40% of the weight of SiO.₂It is poly ethyl silicate, Hexa ethoxy disiloxane, and methyl hydrogen Pori Shiroki Sun which have a content. the example in which the condensation catalyst was known most -- dibutyltin dilaurate and a jib -- it is the tin salt of fatty acid like Tiruzuji acetate and Tin- ()-octoate. If what has an alkenyl group as each reactant end unit exists in diorganopolysiloxane containing a reactant end unit, it will be hardening to an elastomer, It can carry out under existence of the organopolysiloxane which has an average of at least three hydrogen atoms per molecule by which Si combination was carried out, for example, the catalyst which promotes addition of the alkenyl group to the hydrogen combined with Si by the publicly known method using methyl hydrogen Pori Shiroki Sun, for example, platinum () Krol acid. In that case (LTV) the constituent hardened at the temperature (mostly 50 thru/or 80degreeC) slightly raised in room temperature exists. What uses polycyclic type organopolysiloxane under existence of a balance-ized catalyst like Rinni trill chloride as an example of others for hardening to an elastomer is mentioned to the last. Of course, the constituent which can be hardened to an elastomer may contain the bulking agent used for the constituent which can usually mostly or often be hardened to an elastomer other than diorganopolysiloxane, precipitation silicic acid, a hardening agent, and a curing catalyst depending on the case. The example of such a substance is 50 m.²The bulking agent which has the surface area below /g, for example, the end of quartz powder, diatomite and also a zirconium silicate, and calcium carbonate, (The unsettled silica dioxide obtained at high temperature and organic resin, for example, polyvinyl chloride powder) Organopolysiloxane resin, a fibrous bulking agent, for example, asbestos, glass fiber, and organic textiles, paints, soluble dye, a fragrant substance, a corrosion control agent and Agent that stabilizes a constituent to the influence of water, for example, an acetic acid anhydride, and concrete retarder, for example, benzo, -- doria -- it is the dimethylpolysiloxane protected by Sole and Plasticizing agent, for example, a trimethylsiloxy machine, in the end. The combination of the above-mentioned physicochemical data of hydrophobic precipitation silicic acid by the present invention brings about a high effect based on the dispersibility which stood high. The amount of [ which decreased clearly as compared with publicly known precipitation silicic acid ] balanced humidity has the advantage that the vulcanizate which does not have a fine hole as compared with publicly known use of the hydrated precipitation silicic acid, for example in the case of non-pressure vulcanization in the case of processing is obtained. PH value adjusted the optimal is drawn at the softening roll time shortened clearly. The low electrolyte content combined with a part for low humidity is led to the electric nature which was finally excellent in vulcanizate. In the silicone rubber ceiling agent of cold cure nature, hydrophobic precipitation silicic acid by the present invention shows the advantage for the storage stability of the constituent which is not hardened based on the low water content. Hydrophobic precipitation silicic acid by the present invention and its manufacturing method are explained still in detail in the following examples. Example 1 It is water 50.0m to a reaction vessel.³It inserts in. Water glass solution 9.2m³And H₄SO₄0.9m³It adds gradually under churning at Receiver, and adjusts PH value of the mixture under addition to alkalinity in that case. Water glass and H₂SO₄PH value of the obtained suspension is maintained at the acid range after the end of Addition. Using a filter press, it dissociates from a mother liquor, the output which precipitated is washed, and suspension is made with acid water, and it dries with a spray. Subsequently the output by which spray dryness was carried out is ground by a crossing beater mill "Alpine UP630 type" (Typ Alpine UP630). The obtained precipitation silicic acid shows the following physicochemical data: [Table]

The sample of 4.0 kg of operation silicic acid of measurement of an electric conduction rate is heated in a beaker with a capacity of 150 ml with 50 ml of water desalted completely about the substance dry in between, and it boils for 1 minute under churning. Subsequently, this suspension is transferred to a measuring flask with a capacity of 100 ml, and it cools, and fills the water desalted completely to a place with a sign. After shaking, the suspension which should measure the measurement room of a conductivity measuring apparatus first washes beforehand, and subsequently it fills with it, or a measurement room is immersed into suspension. An electric conduction rate is read with a measuring device, and the temperature of the suspension in the case of measurement is measured. Calculation: An electric conduction rate is muS-cm in 20 degreeC.^-1It is come out and given. Example 2 Manufacture of hydrophobic precipitation silicic acid by the present invention: Carry out Across dropping of the thing - ground in the precipitation silicic acid 400g-crossing beater mill of the present invention by Example 1 in 40 minutes under Teguroxane 50 (Tegiloxan50) 44.5g and powerful churning in Paddock Mill. Mixture is continued for 80 more minutes. Powder without Clump is filled to an aluminum plate next, and it applies to heat treatment for 90 minutes in 350 degreeC with about 5 cm[ of - layer / in height ]-, and a muffle furnace. The obtained output is ground by Pettsgill. The chemical / physical data of the obtained output is as follows: [Table]

Teguroxane 50 (Tegiloxan50) is Goldschmidt's (M. Goldschmidt AG, 43Essen) product. It is silicone oil which consists of line dimethylpolysiloxane which has the viscosity of 50cP. An electric conduction rate is measured like Example 1. Measurement of the water wettability of hydrophobic silicic acid In the following analysis method, measurement of the water wettability portion of hydrophobic silicic acid is indicated. Implementation of measurement: Hydrophobic silicic acid 0.200g is put in a 250-ml oscillating funnel with 50 ml of distilled water, and it shakes for 1 minute by the maximum speed using a Turbla mixer (Turbula-Mischer). After neglecting it for a short time, make 45 ml of portions which carried out humidity flow in an evaporating dish, and it is made to evaporate in bathing, and, subsequently dries in 105 degreeC. After neglecting a humid portion for a short time, put back (it is not shake) 45ml which made it circle carefully into an evaporating dish, and it is made to evaporate on bathing, and, subsequently dries in 105 degreeC. Calculation: The weighing value of the dry residual substance -100-/beginning = measurement of % water wettability partial moisture absorption rate In the case of measurement of a moisture absorption rate, the highest moisture absorption rate or temporal moisture absorption rate of silicic acid is connected with temperature and relative air humidity, and is measured. Implementation of measurement: It puts into the equilibrated weighing bottle in which the sample of about 2.5 g of silicic acid dried 0.1 mg correctly, weighs, and dries in 105 degreeC for 2 hours. Weight is measured with the balance for analysis after cooling. Subsequently, the open weighing bottle into which the sample was put is put into the shelf of homoiothermal constant humidity, and is stored at a fixed temperature and relative air humidity. next, the temporal program of a moisture absorption rate -- or the highest moisture absorption rate can be measured. :30degreeC to which measurement is performed on condition of the following like usual, 30% of relative air humidity 30degreeC, and 70% of relative air humidity Calculation: The sample whose weighing value *=% and moisture absorption rate * dryness weighing value -100-/g and the beginning of g and the last did Measurement of the measurement Djibouti Rufuta rate adsorption (DBP) of a DBP adsorption rate using a Plaven- Plast graph (Brabender-Plastograph) is performed using a Brabender- Plast graph, and absorptance is shown. In that case, absorptance is influenced by the hygroscopic-surface-moisture content of the used substance, a particle size, and the first weighing value. DBP adsorption is shown about the substance which does not contain water. In order to carry out this measurement, please refer to the 2nd column of the 30 to 64th line of the German patent No. 1767332. Example 3 In this example, hydrophobic precipitation silicic acid by the present invention manufactured by the method of following Example 2 is processed into various kinds of silicone rubber, And the operation as the bulking agent for reinforcement in the constituent for a two-component system-silicone resin style lump and the constituent for 1 ingredient system-silicone resin ceilings (acetate system) or a thixotropic agent is examined. In the combination of the examination following in the constituent for a 2-ingredient system-silicone resin style lump (low-temperature vulcanization nature), silicic acid is mixed using a day solver (Dissolver): Dimethylpolysiloxane which has a hydroxyl end group Viscosity 1000cSt 45 copies Dimethylpolysiloxane which has a hydroxyl end group Viscosity 18000cSt 45 copies Silicic acid (10%) Ten-copy hardening agent orthosilicic acid ester Dimethylpolysiloxane which has a two-copy hydroxyl end group Viscosity 1000cSt 42.5 copies Dimethylpolysiloxane which has a hydroxyl end group Viscosity 18000cSt 42.5 copies Silicic acid (15%) 15.0-copy hardening agent orthosilicic acid ester Two copies A flow and the hardening characteristic were observed after addition of a hardening agent. About the hardened sample which was stored for three days It pulls and is strength. It is based on DIN53504. Ultimate pace of expansion It is based on DIN53504. tearing -- intensity it is based on DIN53515 -- and Shoah A hardness be alike DIN53505 -- To was measured. Dimethylpolysiloxane which has :hydroxyl machine with which the examination of Test in the constituent for 1 ingredient system-silicone resin-ceilings (low-temperature vulcanization nature) was done based on the following combination table which uses an acetate hardening agent Viscosity 50000cSt 67.8 weight sections Dimethylpolysiloxane which has a trimethylsiloxy end group Viscosity 1000cSt 27.8 weight sections methyltriacetoxysilane 4.4-weight section precipitation silicic acid 17.6 thru/or 24.9 weight sections -- a jib -- Tiruzuji acetate 0.005 weight section Mixing of silicic acid was performed after addition of a hardening agent in the planet type mixer which can be opened. The vulcanizate hardened in paste-like the constituent for ceilings or, and the air during seven days of that was covered over the following examination: (a) Extrusion possibility by ASTM2451-67T (b) Storage possibility by the Hiyutsuchien method (Hu *tchenmethode) (c) The modulus in 100% of growth by DIN53504 (d) it is based on DIN53504 -- pulling -- strength (e) The ultimate pace of expansion by DIN53504 (f) it is based on DIN53515 -- tearing -- intensity (g) Shoah A hardness by DIN53505 [Table]

[Table]

Measurement of the storage stability by the "Hiyutsuchien method" (Hu *tchen methode) is used as a quick method in practice, although not standardized. For the operation, a small quantity is forced on a solid base from a pipe or a pipe, and it draws out in the shape of A tip. The description about the storage stability of A tip-like a form and its forming possibility to an one-ingredient system is possible. The result of an examination When 15% of examination (1st table) silicic acid in the constituent for a 2-ingredient system-silicone resin style lump is added, the mixture which does not use a hardening agent is natural mobility. After adding a hardening agent, a sample shows not thixotropy nature but the natural mobility with which it should be satisfied of the constituent for Inflow. Therefore, hydrophobic precipitation silicic acid according to the present invention shows the advantageous characteristic. It brings a distinct improvement of mechanical strength to a system. Without a bulking agent, it breaks easily and only the output which hardly has the character like rubber is obtained. If the state of the art of the examination (The table) present of the constituent for 1-ingredient system-silicone resin-ceilings is followed, what hydrophobic precipitation silicic acid is used for for mechanical reinforcement is impossible to because of the high moisture absorption degree (this is about 4% at 30degreeC and 70% of relative air humidity) one. Since the water content brought about into a mixture is very high in the case of the degree of restoration of at least 20 copies if it becomes what, a mixture is already hardened in a pipe after a short period of time. using silicic acid 4 by the present invention -- for the first time -- the low degree of moisture absorption (this is about 1.5% at 30degreeC and 70% of relative air humidity) -- therefore, required storage stability -- and -- therefore, the premise for use suitable for practical use is provided. The sample of publicly known hydrophobic precipitation silicic acid is led to hardening which is not desirable in the high degree of moisture absorption, therefore the closed pipe after the storage time on the 1st at the latest, although it may be mixed into a constituent at 15% of concentration. After not hardening in a pipe the mixture manufactured using 15% of hydrophobic precipitation silicic acid by the present invention but hardening in the air moreover, the mechanical numerical value which should be observed is shown. Batches hardened using 20% of hydrophobic precipitation silicic acid by the present invention shows the outstanding storage stability, in a pipe, is not hardened but shows the characteristics required as rubber which stood high. the combination table of the examination following of hydrophobic precipitation silicic acid in heating vulcanization silicone rubber -- therefore, it examines by manufacturing vulcanizate. A result can be compared from a The table: Dimethylpolysiloxane containing a trimethylsiloxy end group and a vinyl group 100 weight sections Silicic acid 1.5 weight sections of 50-weight section Screw- 2 and 4-dichlorbenzoyl peroxide (50% as a paste in silicone oil) Vulcanization: In 130 degreeC, it is for 7 minutes. Post-vulcanization: In 200 degreeC, it is 6 hours. a The table The degree of restoration of test precipitation silicic acid of hydrophobic precipitation silicic acid by the present invention in heating vulcanization silicone rubber: 50-copy Shoah A hardness (1) It pulls 52 and is strength (2) Kg/cm.²85 Ultimate pace-of-expansion (3) % 410 a little more than degree-K g/cm²35 It tears and is intensity (4) Kg/cm. 12 (1) It is based on DIN53505. (2) It is based on DIN53504. (3) It is based on DIN53504. (4) It is based on DIN53515. pulling in the lowest possible value of Shoah A hardness with a high level of the numerical value of strength, an ultimate pace of expansion, and mechanical data like intensity that tears -- heating hardenability silicone rubber -- an intermediary -- it is desirable. From the data of a The table, it becomes clear that the combination of these character is best satisfied with precipitation silicic acid by the present invention. That the Shoah A hardness of the vulcanizate with which it filled up using precipitation silicic acid by the present invention is comparatively low makes it possible to further improve the rate of a bulking agent (to the Shoah A hardness of 60), and this results in having influence advantageous to Machine data on the other hand.