JP2019143259A - Expansible sheet - Google Patents

Abstract

To provide an expansible sheet having excellent shape retention after use.SOLUTION: The present invention provides an expansible sheet containing expansible vermiculite and inorganic fiber, the inorganic fiber having: a first inorganic fiber with a silica content of 70 wt.% or more; and a second inorganic fiber with a silica content of 60 wt.% or less, having an average fiber diameter of 3.0 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inflatable sheet.

  In heating furnaces, internal combustion engines, combustion appliances, and the like, expansive sheets containing vermiculite and inorganic fibers are used as sealing materials that close gaps and joints between members (Patent Documents 1 and 2). The inflatable sheet is installed between two members, and when heated and expanded, the thickness increases and the members are closely attached between the members.

  In such an expandable sheet, a heat-resistant ceramic fiber (RCF) is used as an inorganic fiber. The heat-resistant ceramic fiber is usually an inorganic fiber containing 40 to 60% by weight of silica and 30 to 60% by weight of alumina, and is considered to have higher heat resistance than asbestos and lower health problems than asbestos. Carcinogenicity is suspected. Therefore, there is a demand for replacement with biosoluble inorganic fibers that do not cause problems or are difficult to cause even when inhaled by the human body. Rock wool and alkaline earth silicate (AES) wool are known as biosoluble inorganic fibers. Generally, alkaline earth silicate wool is an inorganic fiber containing silica and magnesia and / or calcia, and usually contains 15 to 50% by weight of magnesia and calcia together, and 50 to 82% by weight of silica.

  AES wool is generally inferior to RCF in heat resistance and alumina resistance. Inorganic fibers having biosolubility and heat resistance and alumina reactivity comparable to RCF have been studied and developed (for example, Patent Documents 3 to 5). These AES wools have a high silica content of 70% by weight or more, have higher heat resistance than conventional AES wools, and some have a heat-resistant temperature as high as 1300 ° C., similar to RCF.

  However, the expansive sheet using AES wool having a silica content of 70% by weight or more as an inorganic fiber has a problem that when it is to be replaced with a new one after use, the shape is fragile and the replacement workability is poor. was there.

JP-A-56-104769 JP 59-21565 A JP 2005-515307 A JP-T-2005-514318 JP 2016-37427 A

  An object of the present invention is to provide an inflatable sheet having good shape retention after use.

  Inorganic fibers containing 70% by weight or more of silica have a high viscosity of the raw material melt at the time of production, so that the curing time is fast and the fiber diameter is thick. When thick fibers are used for the expandable sheet, the number of fibers contained in the expandable sheet is reduced. The present inventors speculated that the shape of the expandable sheet collapsed because the number of fibers contained in the expandable sheet was small and the number of contact points between the fibers decreased, resulting in a weaker reinforcing effect. And it discovered that a shape was maintainable by mixing an inorganic fiber with a small fiber diameter in an expansible sheet, and completed this invention.

According to the present invention, the following inflatable sheet is provided.
1. In an inflatable sheet containing inflatable vermiculite and inorganic fibers,
The inorganic fiber is
A first inorganic fiber having a silica content of 70% by weight or more;
A second inorganic fiber having an average fiber diameter of 3.0 μm or less and a silica content of 60% by weight or less;
An inflatable sheet.
2. 2. The expandable sheet according to 1, wherein the first inorganic fiber contains 15 to 30% by weight of one or more metal oxides selected from calcia and magnesia.
3. 3. The expandable sheet according to 1 or 2, wherein the second inorganic fiber contains 25 to 60% by weight of one or more metal oxides selected from calcia and magnesia.
4). The inflatable sheet according to any one of 1 to 3, wherein the second inorganic fiber is rock wool.
5. The expansible sheet in any one of 1-4 whose ratio of the weight of the 1st inorganic fiber and the 2nd inorganic fiber is the following.
1st inorganic fiber: 2nd inorganic fiber = 85: 15-55: 45
6). The expansible sheet in any one of 1-5 whose ratio of the weight of the 1st inorganic fiber and the 2nd inorganic fiber is the following.
1st inorganic fiber: 2nd inorganic fiber = 75: 25-60: 40
7). The expansible sheet in any one of 1-6 whose average fiber diameter of said 1st inorganic fiber is more than 3.0 micrometers and 8.0 micrometers or less.

  According to the present invention, it is possible to provide an inflatable sheet having good shape retention after use.

It is a figure which shows the compression heating test in an experiment example.

The expandable sheet of the present invention includes expandable vermiculite and inorganic fibers.
The inorganic fiber is preferably a biosoluble fiber. The inorganic fiber is preferably an inorganic fiber containing one or more metal oxides selected from calcia and magnesia and silica. Such inorganic fibers can be used by mixing two or more kinds of inorganic fibers.

  Further, the inorganic fiber is preferably a mixture of a first inorganic fiber having a silica content of 70% by weight or more and a second inorganic fiber having a silica content of 60% by weight or less.

  The first inorganic fiber preferably contains one or more metal oxides selected from calcia and magnesia and silica, for example, 15 to 30% by weight of metal oxide and 70 to 82% by weight of silica.

The second inorganic fiber preferably contains one or more metal oxides selected from calcia and magnesia and silica, for example, 25 to 60% by weight of metal oxide and 30 to 60% by weight of silica. The second inorganic fiber is preferably rock wool.
Since the second inorganic fiber has a low silica content, a fiber having a thin average fiber diameter can be obtained by an industrial production method.

The first and second inorganic fibers can contain other oxides in addition to silica, calcia, and magnesia.
The first inorganic fiber and the second inorganic fiber may be a single type of inorganic fiber or a mixture of different types of inorganic fibers.

The first inorganic fiber preferably contains the following components in the following content.
SiO ₂ : 70% by weight to 82% by weight
One or more selected from MgO and CaO: 15% by weight to 30% by weight
One or more selected from Al ₂ O ₃ , TiO ₂ and ZrO ₂ : 0 wt% to 6 wt%

The content of SiO _{2 in} the first inorganic fiber is preferably 72% to 81% by weight, more preferably 73% to 80% by weight, and still more preferably 75% to 80% by weight.
The content of one or more metal oxides selected from MgO and CaO in the first inorganic fiber is preferably 18% by weight to 29% by weight, more preferably 19% by weight to 28% by weight.
The content of one or more metal oxides selected from Al ₂ O ₃ , TiO ₂ and ZrO _{2 in} the first inorganic fiber is preferably 0% by weight to 4% by weight, for example 0% by weight to 3% by weight. Or it can be 1 to 2 weight%.

The 1st inorganic fiber can contain the following ingredients with the following contents.
SiO ₂ 70 wt% to 82 wt%
CaO 0.5 wt% to 9 wt%
MgO 10 wt% to 29.5 wt%
Al ₂ O ₃ 0% by weight to 3% by weight

Moreover, the 1st inorganic fiber can contain the following components with the following content.
SiO ₂ 70 wt% to 82 wt%
CaO 15 wt% to 30 wt%
MgO 0% to 3% by weight
Al ₂ O ₃ 0% by weight to 5% by weight

Moreover, the 1st inorganic fiber can contain the following components with the following content. This fiber is excellent in heat resistance, alumina reaction resistance and biosolubility.
SiO _2: 72 wt% to 82 wt%
MgO: 8 to 22% by weight
CaO: 4 to 14% by weight
Al ₂ O _3: 0 wt% to 3 wt%
The main component is three components of SiO ₂ , MgO and CaO.
The main component is the three components with the highest content (% by weight) among all the components contained in the inorganic fiber (the component with the highest content, the component with the second highest content, and the content with the third It means that three of the higher components are SiO ₂ , MgO and CaO.

Moreover, the 1st inorganic fiber can contain the following components with the following content. This fiber is excellent in heat resistance, alumina reaction resistance and biosolubility.
SiO _2: 73.6 wt% to 82 wt%
MgO: 9.0 to 21.3% by weight
CaO: 5.1 wt% to 12.4 wt%
Al ₂ O _3: 0 wt% to less than 2.3 wt.% Fe ₂ O _3: 0 wt% to 0.50 wt%
The main component is three components of SiO ₂ , MgO and CaO.

  The first inorganic fiber contains one or more selected from MgO and CaO and silica, preferably 90% by weight or more, for example, 95% by weight, 97% by weight, 98% by weight or 99% by weight or more. be able to.

The content of SiO _{2 in} the second inorganic fiber is 60% by weight or less, for example, 55% by weight or less or 50% by weight or less.
One or more metal oxides selected from MgO and CaO of the second inorganic fiber can be included. The metal oxide content can be, for example, 25-60 wt%, 30-55 wt%, or 30-50 wt%.

  Rock wool can be used as the second inorganic fiber.

The second inorganic fiber includes, for example, the following components in the following content.
SiO ₂ 25~55 weight%
CaO 20-50% by weight
MgO 0-20% by weight
Al ₂ O ₃ 0% to 30% by weight

The second inorganic fiber includes, for example, the following components in the following content.
SiO ₂ 30~50 weight%
CaO 25-45 wt%
MgO 1-15% by weight
Al ₂ O ₃ 5 wt% to 25 wt%

The second inorganic fiber includes, for example, the following components in the following content.
SiO ₂ 35~45 weight%
CaO 30-40% by weight
MgO 4-8% by weight
Al ₂ O ₃ 10 wt% to 20 wt%

  The second inorganic fiber contains one or more selected from MgO and CaO, silica and alumina, preferably 90% by weight or more, for example, 95% by weight or more, 97% by weight or more, 98% by weight or more, or 99% by weight. The above can be included.

  The first and second inorganic fibers are each selected from Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, or a mixture thereof. The oxide may or may not be included. The amount of these oxides may be 3.0% by weight or less, 2.0% by weight or less, 1.0% by weight or less, or 0.5% by weight or less, respectively.

The first and second inorganic fibers may or may not contain each of alkali metal oxides (Na ₂ O, Li ₂ O, K ₂ O, etc.), each of which is 3% by weight or less in total. 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, or 0.1% or less it can.

The first and second inorganic _{fibers, ZnO, B 2 O 3,} P 2 O 5, SrO, Fe 2 O 3, BaO, may or may not contain each of the _Cr 2 _{O 3,} respectively, 3. It can be 0 wt% or less, 2.0 wt% or less, 1.0 wt% or less, 0.5 wt% or less, less than 0.1 wt%, or 0.05 wt% or less.

  Moreover, you may combine the quantity of said each component arbitrarily, respectively.

The dissolution rate constant of the inorganic fiber is preferably 100 ng / cm ² · h or more, 150 ng / cm ² · h or more, 200 ng / cm ² · h or more, 500 ng / cm ² · h or more, 1000 ng / cm ² · h or more, Alternatively, it is 1500 ng / cm ² · h or more. The dissolution rate constant is measured by the method described in the examples.

  The heat shrinkage rate of the first and second inorganic fibers, particularly the heat shrinkage rate of the first inorganic fiber, is preferably 3.5% or less in heating at 800 ° C. for 3 hours when measured by the method described in the examples. More preferably, it is 3.0% or less, and most preferably 2.5% or less.

The first and second inorganic fibers can be produced by a known method such as a melting method.
The average fiber diameter of the first inorganic fiber is usually more than 3.0 μm, for example, 3.2 to 8.0 μm, 3.3 to 7.0 μm, 3.4 to 6.0 μm, or 3.5 to 5. It can be 0 μm. The average fiber diameter of the second inorganic fiber is preferably thin, and is preferably 3.0 μm or less, for example, 1.0 to 2.9 μm or 1.5 to 2.8 μm.

  From the viewpoint of shape retention, the second inorganic fiber is preferably 25% by weight or more, more preferably 30% by weight or more with respect to 100% of the total weight of the first inorganic fiber and the second inorganic fiber. More preferably 50% by weight or more.

  From the viewpoint of shape retention and heat resistance, the ratio of the weight percentage of the first inorganic fiber to the second inorganic fiber (100% in total) is preferably: first inorganic fiber: second inorganic fiber = 85 15:55:45, more preferably, first inorganic fiber: second inorganic fiber = 75: 25-60: 40, and particularly preferably, first inorganic fiber: second inorganic fiber. = 75: 25 to 65:35.

  The inflatable sheet is preferably compressed to 50% of its thickness and held in an atmosphere at 600 ° C. for 5 hours, and then released from compression, and when pressed, it is preferable that the shape does not collapse.

  The expandable sheet includes vermiculite. The vermiculite included in the present invention is expandable.

  The expandable sheet can contain an organic binder, an inorganic binder, a flocculant and the like in addition to inorganic fibers and vermiculite. As long as these do not impair the effects of the present invention, those usually used can be used. Examples of the organic binder include starch, acrylic resin, polyacrylamide, pulp, and acrylic emulsion, and examples of the inorganic binder include colloidal silica such as anionic colloidal silica and cationic colloidal silica, alumina sol, bentonite, and clay mineral. The expansible sheet can be preferably composed of 90% by weight or more, 95% by weight or more, or 98% by weight or more from inorganic fibers, vermiculite, and a binder.

  In general, the inflatable sheet is produced by making a slurry containing each component and then making a paper.

The inorganic fibers used in Experimental Examples 1 and 2 below are as follows.
The average fiber diameter is based on the “Method for Measuring Fiber Diameter of Ceramic Fiber” (prepared on March 30, 2004) prepared by the Technical Committee of the RCF Industry Association. After observing / photographing, the fiber diameter of the photographed fiber was measured, and the average value was obtained. The physiological saline dissolution rate was determined by the following method.

(Biosolubility measurement method)
The fiber was placed on a membrane filter, and physiological saline of pH 4.5 or pH 7.4 was dropped on the fiber with a micropump, and the filtrate that passed through the fiber and filter was stored in a container. The accumulated filtrate was taken out after 24 hours, and the eluted components were quantified with an ICP emission spectrometer, and the solubility was calculated. The measurement elements were the four elements K, Mg, Al, and Si which are main elements.
Dissolution rate constant (unit: unit of surface area / elution amount measured by measuring the average fiber diameter)
ng / cm ² · h).

(1) Alkaline earth silicate (AES)
Composition: SiO ₂ content about 77% by weight, CaO content about 9% by weight, MgO content about 13% by weight, Al ₂ O ₃ content about 1% by weight
Average fiber diameter: 4.2 μm
Dissolution rate constant (pH 7.4): about 1000 ng / cm ² · h
(2) Rock wool A (RW-A)
Composition: SiO ₂ content about 40% by weight, CaO content about 35% by weight, MgO content about 5% by weight, Al ₂ O ₃ content about 13% by weight
Average fiber diameter: 2.6 μm
Dissolution rate constant (pH 4.5): 2000 to 4000 ng / cm ² · h
(3) Rock wool B (RW-B)
Composition: SiO ₂ content about 40% by weight, CaO content about 40% by weight, MgO content about 5% by weight, Al ₂ O ₃ content about 15% by weight
Average fiber diameter: 4.0 μm
Dissolution rate constant (pH 4.5): 2000 to 4000 ng / cm ² · h
(4) Alumina silica fiber Composition: SiO ₂ content about 50% by weight, Al ₂ O ₃ content about 50% by weight
Average fiber diameter: 2.6 μm
Dissolution rate constant (pH 7.4): 10 ng / cm ² · h or less (5) Alumina fiber Composition: SiO ₂ content about 70 to 80 wt%, Al ₂ O ₃ content about 20 to 30 wt%
Average fiber diameter: 3.6 μm
Dissolution rate constant (pH 7.4): 10 ng / cm ² · h or less

Experimental example 1
An inflatable sheet was produced from 100% of each of the above inorganic fibers. Specifically, 100 parts by weight of inorganic fibers, 125 parts by weight of vermiculite, 7.5 parts by weight of pulp, 40 parts by weight of an acrylic emulsion, and 5 parts by weight of a flocculant were dispersed in water to prepare a slurry. This slurry was made into an inflatable sheet.
The following was evaluated about the obtained expandable sheet and inorganic fiber. The results are shown in Table 1.

-Compression heating test As shown in FIG. 1, the sheet | seat 1 was put into the heating apparatus in the state compressed to 50% of initial thickness, and was hold | maintained as it was at 600 degreeC atmosphere for 5 hours. After 5 hours, it was taken out, and the shape retention (brittleness) when releasing the compression was evaluated by palpation according to the following criteria.
◎: Does not collapse even when touched ○: Does not collapse even when touched, but bends when softly lifted △: Slightly collapses when touched ×: Collapses when touched

-Heat expansion ratio The sheet was put into a heating device without being compressed, and kept in an atmosphere of 800 ° C for 30 minutes to expand in the thickness direction. The magnification of the expanded sheet thickness with respect to the thickness before heating was measured.

-Heat shrinkage rate The sheet was put into a heating device without compression, heated in an atmosphere of 800 ° C for 3 hours, and the length before and after heating was measured. The shrinkage ratio of the sheet was calculated from the following formula.
Shrinkage rate = (length before heating−length after heating) / length before heating × 100

Experimental example 2
An inflatable sheet was prepared and evaluated in the same manner as in Experimental Example 1 except that alkali earth silicate and rock wool A were mixed and used as the inorganic fiber. The evaluation results are shown in Table 2. As a comparison, Table 2 also shows the results of the expansion sheet using 100% alumina silica fiber as the inorganic fiber.
Table 2 shows the mixing ratio of alkali earth silicate and rock wool A when the total amount of inorganic fibers is 100 parts by weight.
When a part of the alkaline earth silicate was changed to Rock Wool A, the paper was evenly and evenly placed on the blanket during the production, and the papermaking property was improved.

  From Table 2, it can be seen that when a part of the alkaline earth silicate is changed to rock wool A, the shape retention is improved. Moreover, when the ratio of rock wool A becomes high, it turns out that it is inferior to heat resistance. When the ratio of the weight parts of alkali earth silicate to rock wool A is 83:17 to 58:42, the expandable sheet is excellent in shape retention and heat resistance.

  The inflatable sheet of the present invention is not easily deformed even after being heated in a compressed state for a long time, and is used as a sealing material (packing etc.) for melting aluminum, a joint material, a cable rack, a steel frame, etc. Can be used.

  1 Inflatable sheet

Claims (7)

In an inflatable sheet containing inflatable vermiculite and inorganic fibers,
The inorganic fiber is
A first inorganic fiber having a silica content of 70% by weight or more;
A second inorganic fiber having an average fiber diameter of 3.0 μm or less and a silica content of 60% by weight or less;
An inflatable sheet.   The inflatable sheet according to claim 1, wherein the first inorganic fiber contains 15 to 30% by weight of one or more metal oxides selected from calcia and magnesia.   The inflatable sheet according to claim 1 or 2, wherein the second inorganic fiber contains 25 to 60% by weight of one or more metal oxides selected from calcia and magnesia.   The inflatable sheet according to any one of claims 1 to 3, wherein the second inorganic fiber is rock wool. The expansible sheet according to any one of claims 1 to 4, wherein the ratio of the weight of the first inorganic fiber and the second inorganic fiber is as follows.
1st inorganic fiber: 2nd inorganic fiber = 85: 15-55: 45 The expansible sheet according to any one of claims 1 to 5, wherein the ratio of the weight of the first inorganic fiber and the second inorganic fiber is as follows.
1st inorganic fiber: 2nd inorganic fiber = 75: 25-60: 40   The expandable sheet according to any one of claims 1 to 6, wherein an average fiber diameter of the first inorganic fibers is more than 3.0 µm and not more than 8.0 µm.