JPH0781074B2 - Expandable silicone rubber composition, fire resistant joint sealing material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has a foamable silicone rubber composition, and in particular, has high mechanical strength and maintains its original size and shape even when exposed to high temperatures. Accordingly, the present invention relates to a foamable silicone rubber composition which gives a silicone rubber useful as a fire resistant joint sealing material, a fire resistant joint sealing material obtained by foaming and molding the same, and a method for producing the same.

[Prior Art] Asbestos foam is known as a fire-resistant joint material for construction, and it is certified as a 3-hour fire-resistant material. However, this has a problem in that it affects the health of asbestos. Therefore, the development of this alternative is required.

Therefore, a material made of silicone rubber has been proposed as the fire resistant joint material. However, although this silicone rubber is harmless to humans and animals, when the coefficient of thermal expansion from room temperature to 1,000 ° C is also measured, this silicone rubber gradually expands from room temperature to around 400 ° C as compared to the increase in temperature. At 400-600 ℃, thermal expansion and contraction occur rapidly and the size of the material changes discontinuously, and at 600 ℃ or higher, it shrinks gradually. This is because in the temperature range of 400 to 600 ° C, flammable gas of low molecular weight is generated due to cracking of siloxane main chain, which causes cracks inside the material,
This is because the crack width increases due to shrinkage of ℃ or more, but the occurrence of these cracks increases the possibility of flame spreading to the rear, or the possibility of spread to the rear due to the lack of joint material. Function is reduced.
Therefore, the joint material made of this silicone rubber has the drawback that it is easily burned and disappears when exposed to a high temperature such as a flame, or it falls off from the joint and does not function as a sealing material.

[Problems to be solved by the invention] Therefore, regarding the fire resistant joint sealing material made of this silicone rubber, a platinum compound as a fire resistant agent is added as platinum atoms in an amount of 1 to 2,000 ppm and a ceramicizing agent in an amount of 5 to 45.
A silicone rubber sponge with a weight percentage added is also proposed (see Japanese Patent Publication No. 63-191841).
This also has a drawback that cracks occur in a high-level fire resistance test such as a three-hour fire resistance test, and a flame is spread from a gap between the joint and the joint.

[Means for Solving the Problems] The present invention relates to a foamable silicone rubber composition that solves the above disadvantages and drawbacks, a fire resistant joint sealing material obtained by foaming and molding the same, and a method for producing the same. Is a) average composition formula (Wherein R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group, n is 1.98 to 2.02) 100 parts by weight of the diorganopolysiloxane, b) the specific surface area is 50 m ² / g or more. Reinforcing silica powder 10 to 70 parts by weight, c) General formula MO ・ Fe
20-150 parts by weight of ferrite powder represented by ₂ O ₃ (where M is a divalent metal atom selected from Mn, Cu, Ni, Mg, Co, Zn, Fe), d) 20-200 parts by weight of glass powder Part, 1) as a platinum atom, 1 to the a) component diorganopolysiloxane
A foamable silicone rubber composition comprising 2,000 ppm of platinum or a platinum compound, f) a curing agent, and g) a foaming agent, and a fire resistant joint formed by foaming and molding the composition. The present invention relates to a sealing material and a method for producing a fire resistant joint sealing material obtained by vulcanizing the above-mentioned foamed silicone rubber composition by an ultra high frequency vulcanization method.

That is, the present inventors have excellent shape retention at the time of combustion, the occurrence of cracks is extremely small, and as a result of various studies to develop a joint material having a high degree of fire-resistant sealing property, the known dimethyl silicone rubber, etc. When a silicone rubber composition obtained by adding a filler and a ferrite powder, a glass powder and platinum or a platinum compound, and a known curing agent and a foaming agent to diorganopolysiloxane is foamed and molded, a joint sealant having excellent fire resistance is obtained. It was found that this fire-resistant joint sealing material has excellent shape retention even when exposed to high temperatures during combustion, and that it exhibits a high degree of fire-resistant sealability because it has few cracks. The present invention has been completed by conducting research on a method for producing a sealing material and the types and addition amounts of the components used therein.

This will be described in more detail below.

[Operation] The present invention relates to a foamable silicone rubber composition, a fire-resistant joint sealing material formed by foaming the same, and a method for producing the same.

The diorganopolysiloxane as component a) constituting the foamable silicone rubber composition used for producing the fire-resistant joint sealing material of the present invention has an average compositional formula. In indicated, R ¹ is a methyl group, an ethyl group, a propyl group, an alkyl group such as butyl group, cycloalkyl groups such as a cyclohexyl group, a vinyl group, an allyl group, a butenyl group, an alkenyl group such as hexenyl group, a phenyl group, Selected from an aryl group such as a tolyl group, or a chloromethyl group obtained by substituting a part or all of hydrogen atoms bonded to carbon atoms of these groups with a halogen atom, a cyano group, a trifluoropropyl group, a cyanoethyl group, etc. , An unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which is the same or different, n is an integer of 1.98 to 2.02, and a molecular chain end is a trimethylsilyl group, diethylphenylsilyl Group, a dimethylhydrogensilyl group, a dimethylvinylsilyl group, a trivinylsilyl group and the like. This kind of organopolysiloxane is obtained by (co) hydrolyzing and condensing one or more kinds of usually selected organohalogenosilanes, or by using a cyclic polysiloxane (such as a trimer or tetramer of siloxane) to be alkaline. Alternatively, it can be obtained by ring-opening polymerization using an acidic catalyst, which is basically a linear diorganopolysiloxane, but it is a diorganopolysiloxane having two or more different molecular structures. It may be a mixture. The organopolysiloxane may have a viscosity of 100 cS or higher at 25 ° C.,
Usually, it is good that it is 100,000 to 10,000,000 cS.

The reinforcing silica powder as the component b) constituting the foamable silicone rubber composition is essential for obtaining a silicone rubber having excellent mechanical strength. For this purpose, the specific surface area is It must be 50 m ² / g or more, and typical examples of this include fumed silica and precipitated silica. The amount of the silica powder added is less than 10 parts by weight relative to 100 parts by weight of the diorganopolysiloxane as the component a), which is too small to obtain a sufficient reinforcing effect. Worsened,
Also, the mechanical strength of the resulting foam is reduced, so 10-70
It is required that the amount is parts by weight, but the preferable range is 30 to 50 parts by weight.

Next, the foamable silicone rubber composition is constituted c)
Ferrite powder as a component is an essential component for making silicone rubber refractory. Addition of this reduces thermal expansion and shrinkage changes at 400-600 ° C, and at 600 ° C or higher. The effect of reducing heat shrinkage is provided. This ferrite powder has a general composition formula MO ・ Fe ₂ O ₃
And M is selected from Mn, Cu, Ni, Mg, Co, Zn, Fe 1
Or two or more divalent metal atoms, such as (MnO) _0.5 (ZnO) _0.5 Fe ₂ O ₃ , (NiO) _0.5 (ZnO) _0.5 F
e ₂ O ₃ , (MgO) _0.5 (MnO) _0.5 Fe ₂ O ₃ , (MnO) _0.5 (FeO)
_0.5 Fe ₂ O ₃ , (MnO) _0.32 (ZnO) _0.14 (FeO) _0.04 (Fe
₂ O ₃ ) _0.50 , (MnO) _0.15 (ZnO) _0.35 (Fe ₂ O ₃ ) _0.50 , Fe
O ・ Fe ₂ O ₃ may be used, but the particle size is 0.01
˜15 μm, preferably 0.1 to 5 μm. If the amount added is less than 20 parts by weight based on 100 parts by weight of the diorganopolysiloxane as the component a), sufficient fire resistance cannot be obtained when the sponge material is molded, and exceeds 150 parts by weight. Since the mechanical strength of the sponge material decreases when the amount is set, it is necessary to set the amount in the range of 20 to 150 parts by weight, and the preferable range is 50 to 90 parts by weight. The addition of this ferrite powder improves the microwave absorption properties of this silicone rubber composition and makes it possible to subject this to microwave irradiation vulcanization (UHF vulcanization). There is also an advantage that the production of the foamed molded product by continuous extrusion of the product can be performed with high production efficiency.

Further, d) which constitutes the foamable silicone rubber composition.
Glass powder as a component serves as a binder for maintaining the shape of the molded product and protects the surface of the molded product and also decorates it, but the gasket added with this is TMA (Thermo Mechanical Analysis 4) in the measurement result of
Since the change in thermal expansion and contraction at 00 to 600 ° C is remarkably small, it has an effect of reducing cracking and deformation of the molded product. The glass powder may be made of various silicates, borates and phosphates,
These may be the main components of the frit used for ironware enamel, cloisonne glaze, and the like.

The glass powder has a particle size of 0.1 to 100 μm and a melting point of 30.
It may be in the range of 0 to 1,000 ° C., preferably 400 to 700 ° C., but if the addition amount is less than 20 parts by weight with respect to 100 parts by weight of the diorganopolysiloxane as the component a), the composition of the present application will be described. The cured foam obtained from the product is liable to cause cracks, and physical properties such as strength are deteriorated when the amount is more than 200 parts by weight, so that it is required to be in the range of 20 to 200 parts by weight, The preferred range is 30 to 150 parts by weight.

Platinum or a platinum compound as the component e) which constitutes the foamable silicone rubber composition is for imparting flame retardancy to the silicone rubber composition.
Generation of flammable gas at 400-600 ℃ is greatly reduced, and thermal expansion and contraction changes in TMA (above) measurement are greatly alleviated. Platinum used here may be any one of a platinum element simple substance, a platinum compound, and a platinum complex,
Examples thereof include chloroplatinic acid such as chloroplatinic primary acid and chloroplatinic acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, ether compounds, and complexes with various olefins. 1) to 2,000 as a platinum atom based on the component diorganopolysiloxane.
It is required to be in the range of 0ppm.

In addition, f) which constitutes the foamable silicone rubber composition
The curing agent as a component may be a conventionally known one depending on the mechanism of the crosslinking reaction. Therefore, when this crosslinking reaction is carried out by hydrocarbons, organic peroxides such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide,
p-methylbenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-bis (2,5-t-butylperoxy) hexane, di-t-butyl peroxide, t
-Butyl perbenzoate or the like may be added in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the diorganopolysiloxane as component a) or 0.1 to 1.0% by weight based on the silicone rubber composition. Further, this cross-linking reaction has a hydroxyl group bonded to a silicon atom, an alkoxy group, an acetoxy group,
Alkenyloxy group, acyloxy group, iminoxy group,
Condensation such as dehydration reaction, dealcoholation reaction, decarboxylic acid reaction, deketone reaction, deoxime reaction, deamine reaction, deamidation reaction with hydrolyzable groups such as amine group, amide group, aminooxy group, etc. When the reaction is carried out, the diorganopolysiloxane as component a) is
It is assumed that the end of the molecular chain is blocked with, for example, a dimethylhydroxysilyl group, or a dimethylalkoxysilyl group having a lower alkoxy group such as a methoxy group and an ethoxy group, a methyldialkoxysilyl group, a trialkoxysilyl group, etc. Organic acid salts and organic amines may be used, and examples thereof include organic tin compounds such as dibutyltin dilaurate and tin dioctenoate, and organic titanium compounds such as iron stearate, lead octylate, titanium tetrapropoxide and titanium tetrabutoxide. Examples of the organic acid salts such as compounds, amines such as dibutylamine, triethanolamine and the like. In this case, if necessary, for example, a methoxy group,
Methyltrialkoxysilane, ethyltrialkoxysilane, vinyltrialkoxysilane, phenyltrialkoxysilane, tetraalkoxysilane, and methyltributanooxime having alkoxy groups such as ethoxy group, propoxy group, butoxy group, methoxyethoxy group, and ethoxyethoxy group. Crosslinking agents such as silane, methyltri (hexanoxime) silane, methyltri (isopropenoxy) silane, methyltriacetoxysilane, ethyl orthosilicate, propyl orthosilicate may be used.
Further, when the diorganopolysiloxane as the component a) has an alkenyl group directly connected to a silicon atom, an organohydrogen containing at least two hydrogen atoms directly connected to the silicon atom in one molecule is added to the diorganopolysiloxane. The diene polysiloxane may be used as a curing agent to perform cross-linking by these addition reactions, and thus cured. The organohydrogen polysiloxane used here may be linear, branched or cyclic. Therefore, it may be a diorganopolysiloxane end-capped with a dimethylhydrodienesilyl group, a copolymer of a dimethylsiloxane unit with a methylhydrodienesiloxane unit and a terminal trimethylsiloxy unit, a dimethylhydrodienesiloxane. Unit (H (C
H ₃ ) ₂ SiO _0.5 unit) and a SiO ₂ unit of low viscosity fluid,
1,3,5,7-tetrahydrodiene-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrodiene-1,3,5,7-tetramethyl Cyclotetrasiloxane, 1,5-dihydrodiene-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane and the like are exemplified, but all of these organohydrogenpolysiloxanes have a degree of polymerization of Is preferably 300 or less. The addition amount of the organohydrogenpolysiloxane as the curing agent is such that the hydrogen atom directly bonded to the silicon atom is 50 to 500 mol% with respect to the alkenyl group of the diorganopolysiloxane as the component a). Preferably. It is preferable to add a known platinum-based catalyst to this addition reaction, and the platinum or platinum compound as the above-mentioned component f) can be used as it is. It serves as a flame retardant and can be used as a catalyst for this addition reaction.

Further, g) which constitutes the foamable silicone rubber composition.
The foaming agent as a component is for making the molded product obtained from this composition into a foam, which is stable at room temperature but releases a foaming gas when exposed to high temperatures. If desired, the effervescent gas is generally nitrogen gas, but it may be carbon dioxide or other gas. This may be commercially available, and includes azobisisobutyronitrile, dinitrosopentamethylenetetramine, benzenesulfone hydrazide, N, N'-dinitroso-N, N'-dimethylterephthalamide, azodicarbonamide and the like. As an example, if the addition amount is less than 1 part by weight with respect to 100 parts by weight of the diorganopolysiloxane as the component a), the amount of foaming gas generated is small and the foaming ratio of the target sponge body is small. If the amount is less than 2 times, a good foam cannot be obtained, and if the amount is more than 10 parts by weight, the processability of the composition is deteriorated, and the foaming ratio of the obtained foam becomes a high foam having a larger than 8 times. Since the effect of the present invention is not exhibited, the amount may be in the range of 1 to 10 parts by weight, preferably 3 to 7 parts by weight.

The silicone rubber composition for producing the fire-resistant joint sealing material of the present invention has the above-mentioned components a) to g) uniformly mixed using a rubber kneader such as a two-roll, Banbury mixer or dough mixer (kneader). However, the order of this mixing is not particularly limited, but usually, the components a) and b) are kneaded sufficiently uniformly, and then c). , d), e), f), g), h)
It is advantageous to mix and knead each of the above components.

In addition, if necessary, a colorant may be added to the silicone rubber composition.
Although it is optional to add various additives such as a heat resistance improver, a reaction control agent, a release agent or a dispersant for filler, diphenylsilanediol used as the dispersant for filler. , Various alkoxysilanes, carbon functional silanes, silanol group-containing low-molecular-weight siloxanes, etc. should be minimized so as not to impair the effects of the present invention.

The silicone rubber composition thus obtained is subjected to various molding methods such as cast molding, mold pressure molding, extrusion molding, coating on various base materials, which are conventionally used for molding silicone rubber compositions. The fire resistance is further improved by molding into a sponge-like foam, but if the expansion ratio is less than 2 times, the desired sufficient fire resistance cannot be obtained, and If it exceeds, the mechanical strength of the sponge decreases, so it is preferable to set it to 2 to 8 times. Further, since the sponge body thus obtained is a fire-resistant joint sealing material, the sponge molding is most commonly made by extrusion molding, and the foaming at this time is carried out by the normal pressure hot air vulcanization method (HAV). ), Steam continuous vulcanization method (CV), molten salt vulcanization method (LCM), microwave irradiation vulcanization method (UHF vulcanization), etc., but the fire-resistant joint sealant of the present invention can be used. UHF vulcanization is most preferable for molding. This UHF vulcanization is usually 2,450 ±
Microwaves of 50MHz and 915 ± 25MHz are used to irradiate the object to be processed, and this irradiation generates heat inside the object to be processed, which causes vulcanization. This provides the advantage that the target fire-resistant joint sealing material can be stably and inexpensively produced by continuous extrusion.

[Examples] Next, examples of the present invention and comparative examples will be given. The parts in the examples are parts by weight, and the fire resistance performance of the obtained fire resistant joint sealing material is based on the criteria described below. Is.

(Criteria for fire resistance performance) JIS A1304, Section 3-5 of "Fireproof test method for building structures"
Perform the heating test under the conditions specified in Section,
For the above, the pass / fail is determined according to the criteria of 5-10.

The back surface temperature of the standard sealing material for joints does not exceed 260 ° C, there is no change in fire resistance and structural strength during heating, such as harmful deformation, destruction, and dropout, and cracks through which flame passes during heating. Nothing, the standard sealant for joints does not remarkably ignite during heating, and no fire remains for 10 minutes or more after heating.

Regarding, the pass is marked with ○, and the fail is marked with x.

Examples 1-3, Comparative Examples 1-3 Dimethylsiloxane unit 99.825 mol%, methylvinylsiloxane unit 0.15 mol%, dimethylvinylsiloxy unit
100 parts of a rubber-like organopolysiloxane having an average degree of polymerization of 8,000 consisting of 0.025 mol%, 3 parts of diphenylsilanediol as a dispersant, 4 parts of terminal silanol group dimethylpolysiloxane (polymerization degree n = 10) and a specific surface area of 200 m
40 parts of ² / g fumed silica Aerosil 200 [trade name of Nippon Aerosil Co., Ltd.] was added, kneaded with two rolls, and then heat-treated at 150 ° C. for 4 hours to form a base compound. .

Next, in 147 parts of this base compound, ferrite powder of the kind and amount shown in Table 2, glass powder shown in Table 1, platinum, quartz powder and 0.5 part of 2,4-dichlorobenzoyl peroxide as a curing agent. And 0.5 parts of dicumyl peroxide and 2 parts of azobisisobutyronitrile as a foaming agent were added, and the mixture was kneaded with a two-roll mill to form a foamable silicone rubber composition [Composition No. I to XI (Examples 1 to 1 3, Comparative Examples 1 to 3)] were prepared.

Next, the foamable silicone rubber composition was supplied to an extruder equipped with a die having a cylinder diameter of 40 mmφ / 10 mmφ, a ratio of the cylinder length L to the diameter D of L / D = 12, and 20 mmφ / 100 mmφ. (15 ~ 30 ℃) outer diameter 5mmφ
It is supplied to an extruder equipped with a die of, and from this, at room temperature (15 to 30 ° C), a rod-shaped silicone rubber molded body with an outer diameter of 5 mmφ is continuously extruded at 1 m / min, and the output is 2K.
While irradiating UHF waves of W and frequency of 2,450 MHz, hot air of 200 ° C was circulated, passed through a heating furnace with a total length of 12 m at a transfer speed of 1 m / min to form a sponge, and then dried in a hot air dryer at 200 ° C to Post-curing was carried out for a period of time to complete the cross-linking, and the low-molecular decomposition products were volatilized.

The silicone sponge 1 obtained by cutting the sponge molded in this way to a length of 20 cm has a length of 20 cm, a width of 5 cm, and a thickness of 1 cm.
As shown in FIG. 1, sandwiched between two mortar plates 2 and fixed by a metal jig to prepare a test sample 3 , which was placed in an electric furnace and fed with oxygen under the conditions shown in FIG. When the shape of the sponge sandwiched between the mortar plates was observed after heating and cooling with, the results shown in Table 2 were obtained.

Regarding this silicone sponge 1, a silicone rubber gasket 4 as shown in FIG. 3 is prepared, and this is sandwiched between two ALC plates 5 together with a silicone sealant 6 and a vinyl chloride foam material 7. Create a fireproof joint seal as shown in the figure and attach it to JIS A1304.
When a vulcanization test was performed by heating from the gasket side as shown in FIG. 4 under the conditions specified in Sections 3 to 5, the results shown in Table 3 were obtained.

EFFECTS OF THE INVENTION The present invention has high mechanical strength, and when exposed to high temperature,
The present invention relates to a foamable composition that gives a silicone rubber that maintains the shape of the original size and a fire-resistant joint sealing material obtained by foaming and molding the same, which is, as described above, a) diorganopolysiloxane, b). A foaming agent silicone rubber composition comprising a reinforcing silica powder, c) ferrite powder, d) glass powder, e) platinum, f) a curing agent, and g) a foaming agent, and a fire resistant joint formed by foam molding the same. Regarding the sealing material, this one has a thermal expansion at 400 to 600 ° C because ferrite and glass powder are added,
The shrinkage change is relaxed, the heat shrinkage above 600 ° C is also small, and since platinum is added, the flame retardancy is also good, so the joint sealing material obtained by foam molding this is exposed to high temperature. In addition to having excellent fire resistance, it can maintain its old dimensions and shape, and because it is made of silicone rubber, it also has excellent mechanical strength. Since it can be vulcanized by UHF since it is added, there is an advantage that a thick foam can be stably produced by continuous extrusion at a low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of a fire resistant joint sealant test sample of the present invention, FIG. 2 is a graph showing heating conditions in a heating test of this test sample, and FIG. 3 is a graph showing JIS A1304 “building structure part FIG. 4 is a graph showing this heating condition, and FIG. 4 is a longitudinal sectional view of a fireproof joint seal used in the “fireproof test method”. 1 ... Silicone sponge body, 2 ... Mortar plate, 3 ... Test sample, 4 ... Silicone rubber gasket, 5 ... ACL plate, 6 ... Silicone sealant, 7 ... Vinyl chloride foam material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C09K 3/10 G // C08K 3/22 3/36 3/40 E04B 1/684

Claims (3)

[Claims] 1. A) Average composition formula (Wherein R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group, n is 1.98 to 2.02) 100 parts by weight of the diorganopolysiloxane, b) the specific surface area is 50 m ² / g or more Reinforcing silica powder 10-
70 parts by weight, c) General formula MO ・ Fe ₂ O ₃ (where M is Mn, Cu, Ni, Mg, Co, Zn, F
20 to 150 parts by weight of ferrite powder represented by a divalent metal atom selected from e), 20 to 200 parts by weight of glass powder, e) 1 to platinum component as a component diorganopolysiloxane A foamable silicone rubber composition comprising 2,000 ppm of platinum or a platinum compound, f) a curing agent, and g) a foaming agent. 2. A fire-resistant joint sealing material obtained by foaming and molding the composition according to claim 1. 3. A method for producing a fire-resistant joint sealing material according to claim 2, which is obtained by vulcanizing the composition according to claim 1 by an ultra-high frequency vulcanization method.