JP2023138101A - silicone foam - Google Patents

Abstract

To provide a silicone foam having excellent performance.SOLUTION: A silicone foam contains a foamy silicone resin and a flame retardant, and has a 300°C weight reduction rate of 5.0 wt.% or less.SELECTED DRAWING: None

Description

FIELD OF THE INVENTION This invention relates to silicone foams.

In the field of automobiles and the like, devices are operated in a narrow space, which may cause heat damage to the devices or cause them to catch fire. Therefore, there is a need for a heat insulating material that protects the parts of automobiles and the like from heat.

Patent Document 1 discloses a technique for protecting a floor tunnel around an exhaust pipe and an engine compartment located under the floor of a vehicle from heat using a silicone foam using aluminum hydroxide or the like.

Japanese Patent Application Publication No. 2020-190307

However, the silicone foam according to the prior art did not satisfy sufficient performance.

Therefore, an object of the present invention is to provide a silicone foam having excellent performance.

The present inventors conducted extensive research, found that a specific silicone foam could solve the above problems, and completed the present invention. That is, the present invention is as follows.

An aspect of the present invention is
Contains foam silicone resin and flame retardant,
This silicone foam has a weight loss rate at 300° C. of 5.0% by weight or less as measured by the method described below.
(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), the temperature was raised to 300°C at a heating rate of 10°C/min under a stream of dry air (flow rate: 250 mL/min), and [1- The weight loss rate (weight %) at 300° C. is calculated as (sample weight at 300° C./sample weight before temperature rise starts)]×100.

Another aspect of the invention is
Foamed silicone resin and
A silicone foam containing a flame retardant having a weight loss rate at 300° C. of 20% by weight or less as measured by the method described below.
(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), the temperature was raised to 300°C at a heating rate of 10°C/min under a stream of dry air (flow rate: 250 mL/min), and [1- (Sample weight at 300°C/Sample weight before temperature increase)]×100 to calculate the weight loss rate (weight %) at 300°C.

Yet another aspect of the present invention is
This is a silicone foam containing a foamed silicone resin and a halogen flame retardant.

The silicone foam may be in the form of a sheet.
Silicone foam may also be an insulating material.
The silicone foam may be used in vehicles.

According to the present invention, a silicone foam having excellent performance can be provided.

In the present specification, the notation "a to b" in the explanation of numerical ranges indicates that it is greater than or equal to a and less than or equal to b, unless otherwise specified.

In this specification, when multiple upper limit values and multiple lower limit values are described separately, all numerical ranges that can be set by freely combining these upper limit values and lower limit values are described in this specification. It is assumed that

In this specification, when a certain compound is described, its isomers are also described at the same time.

Embodiments of the present invention will be described in detail below.

<<<Silicone foam>>>
The silicone foam according to this embodiment includes a foamed silicone resin.
In other words, the silicone foam according to this embodiment contains a silicone resin as a component constituting the skeleton of the foam.
Moreover, it is preferable that the silicone foam according to this embodiment contains a flame retardant.
The silicone foam according to this embodiment may contain other components.
Each component will be explained below.

<<Silicone resin>>
The silicone resin forming the silicone foam is a resin having organopolysiloxane as a main chain, and is not particularly limited.

Here, the foamed silicone resin is not particularly limited, and may be produced by various methods. Examples of foamed silicone resins include solid raw material type silicone resins (millable silicone resins, etc.) and liquid raw material type silicone resins (2-component silicone resins, etc.).

Millable silicone resin is a silicone resin obtained by using organopolysiloxane as a main raw material, blending various additives (fillers, dispersants, vulcanizing agents, etc.), kneading, and thermosetting. By using a foaming agent (chemical foaming agent) as an additive, a foamed silicone resin can be obtained.

The two-component silicone resin is, for example, a reaction product of an organopolysiloxane having a predetermined reactive group (hydroxyl group, vinyl group, etc.) and a polysiloxane having an SiH group, and more specifically, " A silanol group-containing organopolysiloxane such as hydroxy group-terminated polydimethylsiloxane or a hydroxyl group-containing compound (foaming aid), and an organohydrogenpolysiloxane such as methylhydrogenpolysiloxane having SiH groups at both ends and side chains. ``Reaction products'' and ``vinyl group-containing organopolysiloxanes such as dimethylpolysiloxanes whose both ends are capped with dimethylvinylsiloxy groups and organohydrogens such as methylhydrogen polysiloxanes having SiH groups at both ends and side chains. and "reaction products with polysiloxane".

The foamed silicone resin may be formed from a one-component silicone resin. A one-component silicone resin is a silicone resin obtained from a composition containing a main component containing an organopolysiloxane having a silanol group at the end, and a crosslinkable silyl group-containing low-molecular compound as a crosslinking component.

The silicone resin is preferably a two-component silicone resin.

The silicone resin may be modified.

<<Flame retardant>>
The flame retardant preferably includes a flame retardant (flame retardant 1) that satisfies predetermined properties.

In another aspect, the flame retardant preferably includes a flame retardant (flame retardant 2) that satisfies predetermined material properties.

The flame retardant 1 and the flame retardant 2 may be the same flame retardant or may be different flame retardants.

The flame retardant may contain a flame retardant other than flame retardant 1 (a flame retardant whose weight loss rate at 300°C is more than 20% by weight).

The flame retardant may contain a flame retardant other than flame retardant 2 (a flame retardant other than the halogen flame retardant).

<Flame retardant 1>
Flame retardant 1 is a flame retardant whose weight loss rate at 300°C measured by the following method is 20% by weight or less (preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably less than 1% by weight). be.

(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), the temperature was raised to 300°C at a heating rate of 10°C/min under a stream of dry air (flow rate: 250 mL/min), and [1- (Sample weight at 300°C/Sample weight before temperature increase)]×100 to calculate the weight loss rate (weight %) at 300°C.

By containing the flame retardant 1 in the silicone foam, it exhibits flame retardant effects in a wide temperature range while maintaining excellent cushioning properties.

Flame retardants satisfying these properties may be organic or inorganic, such as halogen flame retardants, red phosphorus, phosphate esters, phosphate flame retardants, boron flame retardants, antimony flame retardants, It can be selected from carbonates, metal oxides, etc., and preferably selected from halogen flame retardants, phosphate esters, phosphate flame retardants, carbonates, metal oxides, and halogen flame retardants (especially, It is more preferable to select the flame retardant from brominated flame retardants).

One type of flame retardant 1 may be used alone, or two or more types may be used in combination.

When the content of silicone resin in the silicone foam is 100 parts by mass, the content of flame retardant 1 is 0.1 part by mass or more, 0.2 part by mass or more, 0.5 part by mass or more, 1 part by mass. The above amount is preferably 2 parts by mass or more, or 3 parts by mass or more, and 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, and 10 parts by mass or less. It is preferable.

From another point of view, when the content of the entire flame retardant in the silicone foam is 100 parts by mass, the content of the flame retardant 1 is, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more. It is preferably at least 50 parts by mass, at least 60 parts by mass, at least 70 parts by mass, at least 80 parts by mass, at least 90 parts by mass, at least 95 parts by mass, or at least 99 parts by mass.
In other words, when the total content of flame retardants in the silicone foam is 100 parts by mass, the content of flame retardants other than flame retardant 1 (flame retardants whose weight loss rate at 300 °C is more than 20% by weight) is: 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, It is preferably 1 part by mass or less, or 0.1 part by mass or less.

<Flame retardant 2>
Flame retardant 2 is a halogen flame retardant.

By containing the flame retardant 2 in the silicone foam, flame retardant effects can be achieved in a wide temperature range while maintaining excellent cushioning properties.

Examples of the halogen flame retardant include bromine flame retardants, chlorine flame retardants, and the like.

Examples of brominated flame retardants include tetrabromobisphenol A (TBBA) and its derivatives [TBBA epoxy oligomer, TBBA carbonate oligomer, TBBA-bis(dibromopropyl ether), TBBA-bis(aryl ether), etc.], pentabromodiphenyl ether, and octabromobisphenol A (TBBA). Bromodiphenyl ether, decabromodiphenyl ether, bistribromophenoxyethane, ethylenebistetrabromophthalimide, ethylenebispentabromophenyl, dibromophenol, tribromophenol, hexabromobenzene, hexabromocyclododecane, brominated polystyrene, polybrominated styrene, Tris (dibromopropyl)isocyanurate, tris(tribromophenyl)cyanurate, and the like.

The brominated flame retardant is preferably a compound having an aromatic ring substituted with a bromine atom, and more preferably a compound having two or more aromatic rings substituted with bromine atoms at two or more positions.

Examples of chlorinated flame retardants include chlorinated paraffin, perchloropentacyclodecane, and chlorendic acid.

One type of halogen flame retardant may be used alone, or two or more types may be used in combination.

By containing the flame retardant 2 in the silicone foam, flame retardant effects can be achieved in a wide temperature range while maintaining excellent cushioning properties. In particular, when the silicone foam contains a halogen-based flame retardant, methyl radicals (or phenyl radicals) etc. that can be generated from the silicone resin at around 300°C react with halogen radicals to inactivate them, and the generated gas ( It is presumed that the dilution effect of hydrogen bromide, hydrogen chloride, etc.) provides an excellent flame retardant effect.

When the content of silicone resin in the silicone foam is 100 parts by mass, the content of flame retardant 2 is 0.1 part by mass or more, 0.2 part by mass or more, 0.5 part by mass or more, 1 part by mass. The above amount is preferably 2 parts by mass or more, or 3 parts by mass or more, and 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, and 10 parts by mass or less. It is preferable.

From another point of view, when the content of the entire flame retardant in the silicone foam is 100 parts by mass, the content of the flame retardant 2 is, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more. Parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, 95 parts by mass or more, 99 parts by mass or more, or 99.9 parts by mass or more is preferred.
In other words, when the total content of flame retardants in the silicone foam is 100 parts by mass, the content of flame retardants other than flame retardant 2 (flame retardants other than halogenated flame retardants) is 90 parts by mass or less, 80 parts by mass or less. Parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, 1 part by mass or less, or , preferably 0.1 part by mass or less.

<Flame retardants other than halogen flame retardants>
Flame retardants other than halogen flame retardants include known flame retardants known as flame retardants for silicone foam, such as red phosphorus, phosphate esters, phosphate flame retardants, boron flame retardants, and antimony flame retardants. , carbonates, metal oxides, metal hydroxides, and the like.

Examples of the phosphoric acid ester include triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, tricylenyl phosphate, tris (t-butylated phenyl) phosphate, tris (i-propylated phenyl) phosphate, 2-ethylhexyl Aromatic phosphate esters such as diphenyl phosphate; aromatic esters such as 1,3-phenylene bis(diphenyl phosphate), 1,3-phenylene bis(dixylenyl) phosphate, resorcinol bis(diphenyl) phosphate, and bisphenol A bis(diphenyl phosphate) Condensed phosphate ester; halogen-containing phosphate esters such as tris(dichloropropyl) phosphate, tris(β-chloropropyl) phosphate, tris(chloroethyl) phosphate; 2,2-bis(chloromethyl)trimethylenebis(bis( 2-chloroethyl) phosphate), halogen-containing condensed phosphoric acid esters such as polyoxyalkylene bisdichloroalkyl phosphate; and the like.

The phosphate flame retardant may be a monophosphate or a polyphosphate.
Examples of monophosphates include ammonium salts such as ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate; monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium phosphite, and Sodium salts such as disodium phosphate and sodium hypophosphite; potassium salts such as monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium phosphite, dipotassium phosphite, potassium hypophosphite, etc. Salts: Lithium salts such as monolithium phosphate, dilithium phosphate, trilithium phosphate, monolithium phosphite, dilithium phosphite, lithium hypophosphite; barium dihydrogen phosphate, barium hydrogen phosphate, Barium salts such as tribarium phosphate and barium hypophosphite; magnesium salts such as magnesium monohydrogen phosphate, magnesium hydrogen phosphate, trimagnesium phosphate, and magnesium hypophosphite; calcium dihydrogen phosphate, hydrogen phosphate Calcium salts such as calcium, tricalcium phosphate, and calcium hypophosphite; zinc salts such as zinc phosphate, zinc phosphite, and zinc hypophosphite; primary aluminum phosphate, dibasic aluminum phosphate, and tertiary phosphate; Examples include aluminum salts such as aluminum, aluminum phosphite, and aluminum hypophosphite.
Examples of the polyphosphate include ammonium polyphosphate, piperazine polyphosphate, melamine polyphosphate, ammonium amide polyphosphate, and aluminum polyphosphate.

Examples of boron-based flame retardants include borax; boron oxides such as diboron trioxide, boron trioxide, diboron dioxide, tetraboron trioxide, and tetraboron pentoxide; boric acid, lithium borate, sodium borate, Examples include boric acid compounds such as potassium borate, cesium borate, magnesium borate, calcium borate, barium borate, zirconium borate, zinc borate, aluminum borate, and ammonium borate.

Examples of antimony-based flame retardants include antimony oxides such as antimony trioxide and antimony pentoxide; antimonates such as sodium antimonate and potassium antimonate; pyroantimonates such as sodium pyroantimonate and potassium pyroantimonate; etc.

Examples of carbonates include calcium carbonate.

Examples of metal oxides include aluminum oxide and magnesium oxide.

Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, and the like.

<<Other ingredients>>
Other components include, for example, resin components other than those mentioned above, known additives other than flame retardants (for example, catalysts, fillers (silica, talc, kaolin, etc.), flame retardant aids, antioxidants, ultraviolet absorbers, etc.). agents, antibacterial agents, surfactants), etc.

Other components are 100 parts by mass or less, 50 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, when the content of the silicone resin in the silicone foam is 100 parts by mass. The amount may be 1 part by mass or less.

<<<Structure/physical properties/properties of silicone foam>>>
＜＜Thickness＞＞
The silicone foam is preferably in the form of a sheet.
The thickness of the silicone foam is preferably 0.1 to 10 mm, more preferably 0.5 to 5 mm, even more preferably 1 to 5 mm, and particularly preferably 3 to 5 mm.
The thickness of silicone foam can be measured using a dial thickness gauge.

＜＜Density＞＞
The lower limit of the density of the silicone foam is preferably 200 kg/m ³ or more, more preferably 300 kg/m ³ or more, and even more preferably 400 kg/m ^{3 or} more. On the other hand, the upper limit of the density of the silicone foam is preferably 900 kg/m ³ or less, more preferably 800 kg/m ³ or less, and even more preferably 700 kg/m ³ or less.
The density of silicone foam can be measured in accordance with JIS K7222:2005 "Foamed plastics and rubber - How to determine apparent density".

<<Hardness (25%CLD)>>
The hardness (25% CLD (kPa)) of the silicone foam is preferably 1000 kPa or less, 500 kPa or less, 300 kPa or less, 250 kPa or less, 200 kPa or less, 150 kPa or less, or 100 kPa or less.
The hardness (25% CLD (kPa)) of silicone foam is the compressive stress when a φ50 mm sample is compressed by 25% at a rate of 1 mm/min in an environment of normal temperature and normal humidity, based on JIS K6254.
The hardness (25% CLD (kPa)) of silicone foam can be adjusted by changing the material of the silicone resin, the cell diameter and density of the silicone foam, as well as the type and amount of flame retardant used. I can do it.

<<Weight reduction rate>>
The 300°C weight loss rate of the silicone foam may be 5.0% by weight or less, 4.9% by weight or less, 4.8% by weight or less, 4.6% by weight or less, or 4.5% by weight or less. preferable.
The 350°C weight loss rate of silicone foam is 10.0% by weight or less, 9.0% by weight or less, 8.5% by weight or less, 8.0% by weight or less, 7.0% by weight or less, or 6.0% by weight or less It is preferably less than % by weight.
The 500°C weight loss rate of the silicone foam may be 40.0% by weight or less, 38.0% by weight or less, 35.0% by weight or less, 33.0% by weight or less, or 30.0% by weight or less. preferable.
The weight loss rate at 600°C of the silicone foam may be 50.0% by weight or less, 45.0% by weight or less, 40.0% by weight or less, 33.0% by weight or less, or 30.0% by weight or less. preferable.
[300°C weight loss rate of silicone foam]/[500°C weight loss rate of silicone foam] is preferably 1.27 or more, 1.29 or more, or 1.31 or more. The upper limit value is, for example, 1.70 or less, 1.60 or less, or 1.55 or less.
[300°C weight loss rate of silicone foam]/[600°C weight loss rate of silicone foam] is preferably 1.35 or more, 1.37 or more, or 1.39 or more. The upper limit value is, for example, 1.75 or less, 1.65 or less, or 1.60 or less.
[350°C weight loss rate of silicone foam]/[500°C weight loss rate of silicone foam] is preferably 1.23 or more, 1.25 or more, or 1.27 or more. The upper limit value is, for example, 1.70 or less, 1.60 or less, or 1.50 or less.
[350°C weight loss rate of silicone foam]/[600°C weight loss rate of silicone foam] is preferably 1.30 or more, 1.32, or 1.34 or more. The upper limit value is, for example, 1.70 or less, 1.65 or less, or 1.60 or less.

The weight loss rate of silicone foam can be measured by the following method.
(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), under a stream of dry air (flow rate: 250 mL/min), the temperature was raised at a heating rate of 10°C/min to a specified temperature (300°C, 350°C, 500°C). or 600°C), and calculate the weight loss rate (weight %) at each predetermined temperature as [1 - (sample weight at 300°C/sample weight before heating start)] x 100. . The measurement starting temperature is room temperature.

When the weight reduction rate of the silicone foam satisfies the above range, it becomes easy to obtain a silicone foam that has excellent cushioning properties, excellent flame retardancy, and the like.
The weight loss rate of the silicone foam can be adjusted by changing the material of the silicone resin, the cell diameter and density of the silicone foam, and by changing the type and amount of the flame retardant used.

<<800℃ non-ignition>>
The silicone foam preferably has the property of not igniting even when heated to 800°C in a hot plate test (800°C non-ignitability).
When a silicone foam has such properties, it becomes easy to produce a silicone foam having excellent cushioning properties, excellent flame retardancy, and the like. Therefore, it can exhibit sufficient flame retardancy even in applications where it is necessary to form a thin sheet and is expected to be used in a high-temperature environment, such as when used in automobile batteries.
The 800°C hot plate test follows the test method below.
(Test method)
Prepare a test sample of 100 mm x 100 mm.
Confirm that the surface temperature of the hot plate (manufactured by MSA Factory Co., Ltd., product number: PA8020/-CC, plate size: 200 mm x 200 mm) is within the range of 20 to 30°C.
Set the test sample in the center of the hot plate.
A SUS plate (100 mm x 100 mm) and a weight are placed on the hot plate (the total weight of the SUS plate and weight is 2.5 kg).
A hot plate is heated under the following conditions: maximum temperature: 800°C, temperature increase rate: 40°C/min.
Observe whether or not the test sample ignites until the hot plate reaches the maximum temperature (800°C).
If the test sample does not ignite, it is considered to have no ignition point (has the property of not igniting even when heated to 800°C in a hot plate test).
If the test sample ignites, read the temperature displayed on the temperature controller built into the hot plate or the thermocouple set between the hot plate surface and the sample and determine the ignition temperature.

The 800° C. non-ignitability of the silicone foam can be adjusted by changing the material of the silicone resin, the cell diameter and density of the silicone foam, and by changing the type and amount of the flame retardant used.

<<<Method for manufacturing silicone foam>>>
Silicone foam can be manufactured by known methods. An example of a specific method for manufacturing silicone foam will be described below.

The method for producing silicone foam may be a method using solid raw materials or a method using liquid raw materials.

Examples of methods using solid raw materials include a method in which millable silicone resin is foamed using a chemical foaming agent or the like.

A method using a liquid raw material is a method of foaming and curing a liquid composition, such as (Manufacturing method 1) a method of forming a foam by self-foaming using a two-component silicone resin; Method 2) A method of foaming/curing a silicone emulsion composition, and the like.
Manufacturing method 1 and manufacturing method 2, which are preferred manufacturing examples of silicone foam, will be described below.

<<Manufacturing method 1>>
Examples of the method for forming silicone foam include a method of starting a reaction by mixing and stirring two-component liquid silicone to obtain silicone foam.
Specifically, a self-foaming reaction type silicone foam is obtained by foaming (by generated hydrogen gas) and curing by the following reaction carried out in the presence of a catalyst such as a platinum catalyst.
``Silanol group-containing organopolysiloxane such as hydroxy group-terminated polydimethylsiloxane, or hydroxyl group-containing compound (foaming aid) and organohydrogenpolysiloxane such as methylhydrogenpolysiloxane having SiH groups at both ends and side chains. ``reaction'', and ``vinyl group-containing organopolysiloxane, such as dimethylpolysiloxane, which has both ends capped with dimethylvinylsiloxy groups, and organohydrogenpolysiloxane, such as methylhydrogenpolysiloxane, which has SiH groups at both ends and side chains. reaction with
Note that an inert gas such as air or nitrogen may be added when mixing and stirring the two-component liquid silicone raw materials. According to this, more uniform cells can be formed by using the inert gas as a foaming nucleus.

When flame retardants and other components are included as raw materials, these components may be mixed in advance with one liquid (Liquid A) and/or the other liquid (Liquid B) of the two-component liquid silicone raw material. However, it may be added and mixed separately from the two-component liquid silicone raw material.

Specific examples of platinum catalysts include chloroplatinic acid, elemental platinum, chloroplatinic acid hexahydrate, complexes of chloroplatinic acid with sym-divinyltetramethyldisiloxane, dichloro-bis(triphenylphosphine)platinum(II). , cis-dichloro-bis(acetonitrile)platinum(II), dicarbonyldichloroplatinum(II), platinum chloride, and platinum oxide, zero-valent platinum metal complexes, such as Karstedt's catalyst, [Cp*Ru(MeCN) ₃ ]PF ₆ , [PtCl ₂ (cyclooctadiene)], solid platinum supported on a carrier (e.g. alumina, silica or carbon black), platinum-vinylsiloxane complexes (e.g. Ptn(ViMe ₂ SiOSiMe ₂ Vi)c and Pt[ (MeViSiO) ₄ ]d), platinum-phosphine complexes (e.g. Pt(PPh ₃ ) ₄ and Pt(PBU3) ₄ ), and platinum-phosphite complexes (e.g. Pt[P(Oph) ₃ ] ₄ and Pt[ P(Obu) ₃ ] ₄ ), where "Me" represents methyl, "Bu" represents butyl, "Vi" represents vinyl, and "Ph" represents phenyl, and c and d represent natural numbers. represent.

As the hydroxyl group-containing compound (foaming aid), alcohols such as benzyl alcohol and ethanol, and water can be used.
In this case, a stock solution containing a vinyl group-containing organopolysiloxane (main polymer), a hydroxyl group-containing compound (foaming aid), and a catalyst is used as solution A, and a vinyl group-containing organopolysiloxane (main polymer) and an organohydrogenpolysiloxane (crosslinked The foaming reaction and the curing reaction may proceed by preparing a stock solution containing the agent) as the B solution and mixing and stirring the A and B solutions.
The number average molecular weight of the main polymer is preferably 500 to 100,000, more preferably 1,000 to 70,000, even more preferably 1,500 to 50,000. Note that the number average molecular weight refers to a value measured by gel permeation chromatography (GPC) using standard polystyrene.
When using two liquids consisting of liquids A and B as described above, the mixing ratio (mass ratio) of liquids A and B depends on the density of the silicone foam to be obtained, but typically , 100:1 to 100:50.

The above-mentioned liquid A may contain a reinforcing material, a filler for imparting functionality, and the like.

The reaction time during hydrogen generation is appropriately adjusted depending on the density of the silicone foam to be obtained, but is usually 1 to 10 minutes, preferably 2 to 6 minutes. The mixing temperature is appropriately adjusted depending on the density of the silicone foam to be obtained, but is usually room temperature.

The density etc. of the silicone foam can be adjusted by optimizing the temperature during curing and foaming (molding), the amount of foaming aid, and the ratio of liquid A and liquid B (the amount of Si-H added).

<<Manufacturing method 2>>
Silicone foams can also be obtained by foaming/curing silicone emulsion compositions.

<Raw materials>
The silicone resin used in the silicone emulsion composition is not particularly limited as long as it contains a silane compound as a raw material monomer, and includes dimethyl silicone, methylphenyl silicone, various modified silicones (e.g., amino-modified silicone, epoxy-modified silicone, polyether-modified silicone, etc.). silicone emulsions, alkyl-modified silicone emulsions, fluorine-modified silicones, etc.) can be used.
A silicone emulsion composition can be produced, for example, by blending raw material monomers for the resin component in an aqueous medium and subjecting the raw material monomers to emulsion polymerization in the presence of various additives such as an emulsifier and a polymerization initiator. . The silicone emulsion composition may be used by blending an emulsion containing resin other than silicone resin, such as acrylic resin, polyurethane resin, polyester resin, or polyepoxy resin.
The raw material may also contain flame retardants and other components.

<Preparation process>
In the preparation step, a silicone emulsion composition, which is a raw material mixture for silicone foam, is prepared by mixing the above-mentioned raw materials. The mixing method is not particularly limited, but for example, the components may be mixed while being stirred in a container such as a mixing tank in which the components are mixed.

<Foaming/hardening process>
In the foaming/curing step, a specified foaming gas is added to the silicone emulsion composition obtained in the preparation step, and these are sufficiently mixed to form a state in which many air bubbles are present in the silicone emulsion composition (foamed emulsion composition). to make something This foaming/curing step is usually carried out by sufficiently mixing the liquid silicone foam raw material mixture obtained in the raw material preparation step and foaming gas using a mixing device such as a mixing head.

<Foaming gas>
The foaming gas mixed into the emulsion composition during the stirring and foaming process forms cells in the silicone foam, and the amount of foaming gas mixed in determines the density etc. of the resulting silicone foam. . In order to adjust the density of the silicone foam, the required silicone foam raw material is determined based on the desired silicone foam density and the volume of the silicone foam raw material (e.g., the internal volume of the mold into which the silicone foam raw material is injected). What is necessary is to calculate the mass of the foaming gas and determine the amount of foaming gas so as to obtain the desired volume based on this mass. Moreover, as the type of gas for foaming, air is mainly used, but inert gases such as nitrogen, carbon dioxide, helium, and argon can also be used.

<Foaming method/foaming conditions>
The foaming method used in the silicone foam preparation method includes a mechanical flossing method. The mechanical floss method is a method in which a silicone emulsion composition is stirred with a stirring blade or the like to mix air from the atmosphere into the emulsion composition and foam it.

As the stirring device, any stirring device generally used in the mechanical floss method can be used without any particular restriction, but for example, a homogenizer, a dissolver, a mechanical floss foaming machine, etc. can be used. According to this mechanical floss method, silicone foams with densities suitable for various uses can be obtained by adjusting the mixing ratio of the emulsion composition and air.

The mixing time of the silicone emulsion composition and air is appropriately adjusted depending on the density of the desired silicone foam, etc., but is usually 1 to 10 minutes, preferably 2 to 6 minutes. The mixing temperature is appropriately adjusted depending on the density of the desired silicone foam, etc., but is usually room temperature.

The stirring speed during mixing is preferably 200 rpm or more (more preferably 500 rpm or more) to make the bubbles finer, and preferably 2000 rpm or less (more preferably 800 rpm or less) to ensure smooth discharge of the foam from the foaming machine.

In the manner described above, a foamed silicone emulsion composition (foamed silicone emulsion composition), in other words, a silicone foam can be obtained.

<<<Applications of silicone foam>>>
The silicone foam according to this embodiment has excellent flame retardancy/insulating properties/cushioning properties, and can therefore be preferably used as a heat insulating material.
Furthermore, since the silicone foam according to this embodiment has sufficient performance even in the form of a thin sheet, it can be preferably used for automotive applications (protective/insulating materials for vehicle components such as engines, batteries, ceilings, floors, and door panels). , can be particularly preferably used as a cushion between cells of an EV battery.

The silicone foam according to this embodiment can also be used for construction (walls, ceilings, roofs, floors, etc.), fittings (windows, shoji screens, doors, sliding doors, transoms, etc.), and for ships for transporting oil and gas. For storage tanks, for aircraft, for transport aircraft, for freezing and cold storage rooms, for plant facilities, for electrical appliances (air conditioners, refrigerators, etc.), for electronic equipment, for retaining walls, for buildings (tunnels, bridges, floating piers) etc.), cold bags for transporting medicine, thermal resistance mitigation materials, underground filling reinforcing materials during ground subsidence prevention work and road construction, heat insulation materials, energy absorbing materials, waterproofing materials, water-stopping materials, buoyancy materials, etc. It can be used for the following purposes.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may also be adopted.

EXAMPLES The present invention will be explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<<<Raw materials>>>
<<Silicone resin raw material>>
Liquids A and B shown in Table 1 were used as raw materials for silicone resin.

<<Flame retardant>>
The flame retardant shown below was used. The weight loss rate at 300°C is a value measured using the method described above.

<Brominated flame retardant>
・FG-7000
Manufactured by Teijin Chemicals 300℃ weight loss rate: less than 1% by weight FG-7500
Manufactured by Teijin Chemicals 300℃ weight loss rate: less than 1% by weight FG-8500
Manufactured by Teijin Chemicals 300℃ weight loss rate: less than 1% by weight SAYTEX BT-93
Manufactured by ALBEMARLE 300℃ Weight loss rate: Less than 1% by weight SAYTEX 8010
Manufactured by ALBEMARLE 300℃ Weight loss rate: Less than 1% by weight

<Metal hydroxide (aluminum hydroxide)>
・B-325
Made by Armorix 300℃ weight loss rate: 27% by weight

<Carbonate (calcium carbonate)>
・Minor calcium carbonate Manufactured by Ohmi Chemical Industry Co., Ltd. Weight loss rate at 300℃: Less than 1% by weight

<<<Example 1>>>
In a room temperature (25°C) environment, liquid A, liquid B, and a flame retardant were mixed in the proportions shown in Table 2, using a stirring device under stirring conditions of a rotation speed of 100 rpm and a stirring time of 30 seconds. Stirred. Next, pour the stirred mixture into the mold, place PET base materials on both sides of the mold, sandwich the mold between a pair of PET base materials, and pour the mixed liquid to the thickness of the mold. Stretch. In this state, the reaction was carried out under the conditions of a heating temperature of 60°C and a heating time of 3 minutes, and then a further reaction was carried out under the conditions of a heating temperature of 120°C and a heating time of 3 minutes with one side of the PET base material peeled off. A silicone foam of No. 1 was obtained.

<<<Example 2-16, Comparative Example 1-6>>>
Silicone foams of each Example and each Comparative Example were obtained in the same manner as in Example 1 except that the raw materials were changed to the proportions shown in Table 2 or Table 3.

<<<Measurement/Evaluation>>>
For each silicone foam, moldability, thickness, density, 25% CLD, 800°C non-ignition property (presence or absence of ignition point), and weight loss rate at specified temperatures (300°C, 350°C, 500°C, 600°C) were measured. .
Moldability was evaluated according to the following criteria, and other items were measured or evaluated according to the methods described above.
The evaluation results are shown in Tables 2 and 3.

<<Moldability>>
A: There was no problem in sheet molding B: It was difficult to mold sheet C: It was impossible to mold sheet

Claims (6)

Contains foam silicone resin and flame retardant,
A silicone foam having a weight loss rate at 300°C of 5.0% by weight or less as measured by the following method.
(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), the temperature was raised to 300°C at a heating rate of 10°C/min under a stream of dry air (flow rate: 250 mL/min), and [1- The weight loss rate (weight %) at 300° C. is calculated as (sample weight at 300° C./sample weight before temperature rise starts)]×100. Foamed silicone resin and
A silicone foam comprising a flame retardant having a weight loss rate at 300° C. of 20% by weight or less as measured by the method below.
(Method)
Using a differential thermal/thermogravimetric simultaneous analyzer (TG/DTA), the temperature was raised to 300°C at a heating rate of 10°C/min under a stream of dry air (flow rate: 250 mL/min), and [1- (Sample weight at 300°C/Sample weight before temperature increase)]×100 to calculate the weight loss rate (weight %) at 300°C. A silicone foam containing a foamed silicone resin and a halogen flame retardant. The silicone foam according to any one of claims 1 to 3, which is in the form of a sheet and has a thickness of 0.1 to 10 mm. The silicone foam according to any one of claims 1 to 4, which is a heat insulating material. The silicone foam according to any one of claims 1 to 5, which is for use in a vehicle.