JP2021143323A - Refractory material - Google Patents

Abstract

To provide a refractory material capable of inhibiting a cold flow.SOLUTION: The refractory material contains a rubber constituent, a thermally expandable graphite, and an inorganic filler. Based on 100 pts.mass of the rubber constituent, the content of the thermally expandable graphite is 5-400 pts.mass, and the content of the inorganic filler is 50-600 pts.mass. The rubber constituent has a gel fraction of 1-70 mass%.SELECTED DRAWING: None

Description

The present invention relates to a refractory material containing a rubber component.

Patent Document 1 discloses a refractory material containing a rubber component, heat-expandable graphite, and aluminum phosphite.

Japanese Unexamined Patent Publication No. 2006-274134

If the refractory material contains a rubber component, it may be deformed by cold flow during the storage process. Therefore, it has been required to suppress deformation due to cold flow.

The present invention has been made in view of such circumstances, and provides a refractory material capable of suppressing cold flow.

According to the present invention, it is a fireproof material containing a rubber component, a heat-expandable graphite, and an inorganic filler, and the content of the heat-expandable graphite is 5 to 400 mass by mass with respect to 100 parts by mass of the rubber component. A fire-resistant material is provided in which the content of the inorganic filler is 50 to 600 parts by mass and the rubber component has a gel content of 1 to 70% by mass.

According to the refractory material of the present invention, cold flow can be suppressed.

The refractory material of the present invention contains a rubber component, a heat-expandable graphite, and an inorganic filler. This refractory material is, for example, a sheet-shaped refractory sheet. The thickness of the refractory sheet is, for example, 1 to 10 mm. The refractory sheet may be rolled into a roll and stored or transported as a refractory sheet roll. If individual refractory sheets are laminated or stored with the refractory sheet roll upright, the cold flow may deform the sides of the refractory sheet so that the center in the thickness direction is dented. Since such deformation deteriorates the appearance of the refractory sheet, it is one of the subjects of the present invention to suppress such deformation. The shape of the refractory material does not have to be a sheet shape, and may be another shape such as a block shape. Further, the refractory material may be a molded product molded into a shape suitable for the intended use. Examples of the molding method include press molding, and examples of the molded product include joint materials for refractory double-layer pipes.

Further, the refractory material exhibits fire resistance by starting thermal expansion at, for example, 200 ° C. or higher and forming a strong heat insulating layer. The expansion ratio is, for example, 3 to 30 times, preferably 5 to 25 times, and even more preferably 7 to 20 times.

Hereinafter, each component will be described in detail.

<Rubber component>
The rubber component used in the fireproof material of the present invention includes, for example, a diene rubber such as natural rubber, isoprene rubber, styrene-butadiene rubber, and chloroprene rubber, and a small amount of double in the main chain such as butyl rubber and ethylene-propylene rubber. Examples include rubber having a bond introduced (for example, ethylene-propylene-diene rubber). In the refractory sheet of the present invention, not only these single substances but also two or more kinds may be mixed and used in order to improve kneadability, moldability and the like.

The rubber component has a gel fraction of 1 to 70% by mass. Cold flow cannot be prevented if the gel fraction is less than 1% by mass. If it exceeds 70% by mass, the dispersibility at the time of kneading deteriorates. The gel fraction is preferably 5 to 50% by mass, more preferably 10 to 30% by mass. The gel component is a component in which rubber is three-dimensionally crosslinked, and by containing a predetermined amount of the gel component, the mechanical strength of the refractory material is increased and cold flow is suppressed.

Since the gel component is produced by cross-linking the rubber component, the gel component can be increased or decreased by changing the degree of cross-linking of the rubber component. Examples of the method for changing the degree of cross-linking include a method of changing the degree of sulfur vulcanization and peroxide cross-linking of the rubber component, and a method of changing the amount of recycled rubber having a relatively high gel fraction.

The gel content is a component insoluble in toluene, and the gel content is a value calculated by the following method.
(A) Approximately 5.0 g of rubber component is weighed (W1).
(B) The weighed rubber component is immersed in 100 mL of toluene at room temperature for 7 days.
(C) Weigh the # 40 mesh of SUS304 (W2).
(D) The immersed rubber component is filtered through a weighed mesh.
(E) The residue on the mesh was dried at room temperature for 7 days, further dried at 80 ° C. for 24 hours, and the residue was weighed together with the mesh (W3).
(F) Gel fraction = ((W3-W2) / (W1)) x 100 (%)

The rubber component preferably contains recycled rubber. Recycled rubber is made by subjecting vulcanized rubber to heat, pressure, and physical treatment to give it adhesiveness and plasticity again so that it can be used for the same purpose as raw rubber. Examples of the recycled rubber include those derived from natural rubber, butyl rubber, SBR and mixtures thereof.

The gel fraction of the recycled rubber is preferably 30% by mass or more, preferably 30 to 90% by mass, further preferably 50 to 85% by mass, still more preferably 60 to 80% by mass. Cold flow resistance can be effectively enhanced by adding recycled rubber having such a gel fraction.

The ratio of the recycled rubber in the rubber component is preferably 2 to 90% by mass, more preferably 10 to 60 parts by mass, still more preferably 20 to 40 parts by mass. In this case, the dispersibility of the recycled rubber tends to be good.

<Heat-expandable graphite>
Thermally expandable graphite is obtained by treating powders such as natural graphite and thermally decomposed graphite with an inorganic acid such as sulfuric acid and nitric acid and a strong oxidizing agent such as concentrated nitric acid and permanganate to maintain a graphite layered structure. It is a graphite compound. When exposed to a temperature of about 200 ° C. or higher, these thermally expand 100 times or more. As for these powders of natural graphite, pyrolytic graphite and the like, in addition to the deoxidizing treatment, there are various types such as a neutralized type and all of them can be used.

The particle size of the heat-expandable graphite is preferably about 20 to 400 mesh (measured by JIS Z 8901). If the particle size is smaller than 400 mesh, the degree of expansion of the heat-expandable graphite is small, and the obtained refractory material may not expand sufficiently in the event of a fire. Elasticity may decrease.

The content of the heat-expandable graphite is 5 to 400 parts by mass, preferably 10 to 300 parts by mass, and more preferably 30 to 150 parts by mass with respect to 100 parts by mass of the rubber component. If the content of thermally expandable graphite is less than 5 parts by mass, the obtained refractory material may not expand sufficiently in the event of a fire, and if it exceeds 400 parts by mass, the coefficient of thermal expansion increases, but the strength of the obtained refractory material There is a tendency that the physical properties of the refractory material deteriorate, and the shape stability after the refractory material expands.

<Inorganic filler>
The inorganic filler is not particularly limited, and is, for example, aluminum phosphite, silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, magnesium oxide, iron oxide, aluminum hydroxide, magnesium hydroxide, zinc borate. , Calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, talc, clay, mica, bentonite, active white clay, sepiolite, glass fiber, glass beads, aluminum nitride, nitrided Examples thereof include boron, carbon black, graphite and ammonium polyphosphate. These may be used alone or in combination of two or more. By adding the inorganic filler, the cold flow resistance, shape retention and flame retardancy of the refractory material can be improved. From the viewpoint of dispersibility, the volume average particle size of the inorganic filler is preferably 1 to 50 μm as measured by the laser diffraction method.

The content of the inorganic filler is 50 to 600 parts by mass, preferably 80 to 550 parts by mass, more preferably 100 to 500 parts by mass, and even more preferably 200 to 450 parts by mass with respect to 100 parts by mass of the rubber component. If it is less than 50 parts by mass, the flame retardancy tends to deteriorate, and if it exceeds 600 parts by mass, the flexibility and strength tend to decrease.

The inorganic filler preferably contains aluminum phosphite. In this case, the shape retention after the heat-expandable graphite contained in the refractory material expands tends to be good. From the viewpoint of dispersibility, the volume average particle diameter of aluminum phosphite is preferably 1 to 100 μm as measured by a laser diffraction method.

The content of aluminum phosphite is preferably 10 to 300 parts by mass, more preferably 13 to 280 parts by mass, and even more preferably 50 to 250 parts by mass with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, the shape retention tends to deteriorate, and if it exceeds 300 parts by mass, the flexibility tends to decrease.

The inorganic filler preferably contains a metal hydroxide such as aluminum hydroxide or magnesium hydroxide. In this case, the temperature rise is suppressed by endothermic heat due to the dehydration reaction during heating. The metal hydroxide is preferably aluminum hydroxide. The content of the metal hydroxide is preferably 10 to 300 parts by mass, more preferably 50 to 250 parts by mass with respect to 100 parts by mass of the rubber component.

<Vulcanizing agent and vulcanization accelerator>
The refractory material of the present invention may contain a vulcanizing agent and a vulcanization accelerator. The vulcanizing agent and the vulcanization accelerator improve the degree of cross-linking of the vulcanizable rubber and improve the strength of the rubber itself. The strength of rubber can be evaluated by hardness. However, the refractory material of the present invention does not have to contain a vulcanizing agent and a vulcanization accelerator. In other words, the refractory material of the present invention does not have to be vulcanized. If the refractory material is not vulcanized, cold flow is likely to occur. Therefore, the technical significance of applying the present invention is remarkable when the refractory material is not vulcanized.

<Other ingredients>
In the present invention, a plasticizer, a softening agent, an antiaging agent, a processing aid, a lubricant, a tackifier, etc. used in ordinary rubber formulations may be used in combination as long as the effect is not impaired. Examples of softeners and plasticizers that are effective in adjusting moldability include paraffin-based and naphthen-based process oils, liquid paraffins and other paraffins, waxes, silicone oils, liquid polybutenes, and other synthetic polymer-based softeners. Examples thereof include phthalic acid-based and adipic acid-based, ester-based plasticizers such as sebacic acid-based and phosphoric acid-based, stearic acid and its esters, alkyl sulfonic acid esters and tackifiers.

The fireproof material of the present invention is obtained by kneading each of the above components using a known kneading device such as a Banbury mixer, a kneader mixer, or a double roll, for example, press molding, roll molding, extrusion molding, calendar molding, or the like. It can be obtained by molding into a sheet by a known molding method.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but these Examples do not limit the present invention.

1. 1. Preparation of Refractory Materials The components shown in the formulations shown in Tables 1 to 3 were kneaded at 120 ° C. for 2 minutes using a kneader mixer having a capacity of 3 liters. Next, the obtained kneaded product was pressed with a hot press to obtain a sheet-shaped refractory material having a thickness of 5 mm.

The details of the components in the table are as follows.
(1) Rubber component Butyl 268 (0%): Butyl rubber ("Butyl 268" manufactured by JSR Corporation, gel fraction 0%)
IIR-S (75%): Recycled rubber ("IIR-S" manufactured by Iwago Kogyo Co., Ltd., gel fraction 75%)

The gel fraction was measured by the following method.
(A) Weigh the rubber component (W1).
(B) The weighed rubber component is immersed in toluene at room temperature for 7 days.
(C) Weigh the # 40 mesh of SUS304 (W2).
(D) The rubber component immersed in the weighed mesh is filtered.
(E) The residue on the mesh was dried at room temperature for 7 days, further dried at 80 ° C. for 24 hours, and the residue was weighed together with the mesh (W3).
(F) Gel fraction = ((W3-W2) / (W1)) x 100 (%)

(2) Thermally expandable graphite Thermally expandable graphite SS-3: "SS-3" manufactured by Air Water Chemical Inc. (60% by mass or more has a particle size of 50 mesh or more)
(3) Inorganic filler Aluminum phosphate: "APA-100" manufactured by Taihei Kagaku Sangyo Co., Ltd. (average particle size 50 μm)
Aluminum hydroxide: "C-301N" manufactured by Sumitomo Chemical Co., Ltd. (average particle size 1.5 μm)
(4) Softener Softener LV-100: Liquid rubber ("Nippon Oil Polybutene LV-100" manufactured by JXTG Energy Co., Ltd.)

2. Evaluation The following measurements and evaluations were performed on the refractory materials of each Example and Comparative Example. The results are shown in Tables 1 to 3.

Comparing Examples 1 to 11 with Comparative Examples 1 to 2, the cold flow resistance is imparted without impairing the dispersibility by setting the gel fraction of the rubber component to 1 to 70% by mass. I know I can do it.

Comparing Examples 4 and 12 to 13 with Comparative Examples 3 to 4, the heat-expandable graphite content is set to 5 to 400 parts by mass with respect to 100 parts by mass of the rubber component. It can be seen that the shape retention can be improved.

Comparing Examples 4 and 14 to 15 with Comparative Examples 5 to 6, the flexibility and difficulty are achieved by setting the content of the inorganic filler to 50 to 600 parts by mass with respect to 100 parts by mass of the rubber component. It can be seen that the flammability can be improved.

The details of the evaluation method are as follows.

<Cold flow resistance>
A refractory material having a thickness of 5 mm was cut into 50 mm square pieces, and 10 sheets of the refractory material were laminated while being sandwiched between release papers. The laminate was allowed to stand in an oven at 40 ° C. with the side side facing down for 30 days, and the dents generated in each of the 10 refractory materials were measured. Then, the depth of the deepest dent was used as an index value. The smaller the index value, the less likely it is that deformation due to cold flow will occur, and based on the index value, cold flow resistance was evaluated according to the following criteria.
×: Index value is 5 mm or more Δ: Index value is 3 mm or more and less than 5 mm ○: Index value is 1 mm or more and less than 3 mm ◎: Index value is less than 1 mm

<Flexibility>
Punch the test piece into the shape of a No. 1 dumbbell from a refractory material with a thickness of 5 mm, gradually lift both ends of the test piece while pressing the center of the test piece, and the angle at the time when the test piece cracks (center and The angle between the straight line connecting one end and the straight line connecting the center and the other end) was measured and evaluated according to the following criteria.
X: A crack was generated at an angle of less than 45 degrees.
Δ: A crack was generated at an angle of 45 degrees or more and less than 90 degrees.
◯: A crack was generated at an angle of 90 degrees or more and less than 180 degrees.
⊚: No crack occurred even at an angle of 180 degrees.

<Thermal expansion property>
A refractory material having a thickness of 5 mm, a width of 30 mm, and a length of 30 mm was heat-treated at 300 ° C. for 0.5 hours, and the expansion ratio was measured and evaluated according to the following criteria.
×: 1 times or more and less than 3 times Δ: 3 times or more and less than 6 times ○: 6 times or more and less than 10 times ◎: 10 times or more

<Shape retention>
After evaluating the above thermal expansion property, the shape stability when the sample was lifted by a finger was evaluated visually and by touch according to the following criteria.
⊚: Even if it was lifted with a finger and dropped from a height of 30 cm, it did not lose its shape.
◯: It did not lose its shape when lifted with a finger, but it lost its shape when dropped from a height of 30 cm.
Δ: Although it has a shape, it collapsed when held by hand.
×: It had no shape and could not be lifted by hand.

<Dispersiveness (mixability)>
The components shown in the formulations of Examples and Comparative Examples were kneaded at 120 ° C. for 2 minutes using a kneader mixer having a capacity of 3 liters, and then the kneaded compound was observed under a microscope and evaluated according to the following criteria.
⊚: 0 to 2 rubber components of 2 mmφ or more in 10 cm □ ○: 3 to 5 rubber components of 2 mmφ or more in 10 cm □ △: 6 to 10 rubber components of 2 mmφ or more in 10 cm □ ×: 2 mmφ or more 11 or more rubber components in 10 cm □

<Flame retardant>
The oxygen index was measured using a combustion test device (manufactured by Suga Test Instruments Co., Ltd., ON-1D type) according to JIS K7201, and the flame retardancy was evaluated according to the following criteria.
×: Less than 30 Δ: Oxygen index is 30 or more and less than 40 ○: Oxygen index is 40 or more and less than 50 ◎: Oxygen index is 50 or more

Claims (7)

A fireproof material containing a rubber component, a heat-expandable graphite, and an inorganic filler, wherein the content of the heat-expandable graphite is 5 to 400 parts by mass with respect to 100 parts by mass of the rubber component, and the inorganic filler. The rubber component is a fire-resistant material having a gel content of 1 to 70% by mass. The refractory material according to claim 1.
A refractory material having a gel fraction of 5 to 50% by mass. The refractory material according to claim 1 or 2, wherein the rubber component includes recycled rubber. The refractory material according to claim 3, wherein the recycled rubber has a gel fraction of 30% by mass or more. The refractory material according to claim 3 or 4, wherein the proportion of the recycled rubber in the rubber component is 2 to 90% by mass. The refractory material according to any one of claims 1 to 5.
A refractory material in which the content of the heat-expandable graphite is 10 to 300 parts by mass with respect to 100 parts by mass of the rubber component. The refractory material according to any one of claims 1 to 6.
The inorganic filler contains aluminum phosphite and contains
A refractory material having an aluminum phosphate content of 10 to 300 parts by mass with respect to 100 parts by mass of the rubber component.