JPH0255396B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION This invention relates to flocked mineral materials, and more particularly to flocked mineral materials that can be used in the production of water-resistant, non-asbestos high temperature products. BACKGROUND OF THE INVENTION Non-asbestos papers and sheets are known to be manufactured from water-swellable mineral materials, particularly swollen silicate gels. For example, U.S. Pat.
No. 4,239,519 relates to the production of inorganic, crystal-containing gelling, water-swellable sheet silicates and articles such as paper, fibers, films, boards and coatings made therefrom. These non-asbestos papers and sheets exhibit good high temperature stability and good chemical resistance. Moreover, since no asbestos fibers are used in their manufacture, such articles do not have the health hazards associated with articles containing asbestos. U.S. Pat. No. 4,239,519 discloses a method for producing a gelling silicate precursor for use in the production of non-asbestos paper and sheet products, which involves three basic steps: The manufacturing method includes (a) fluorhectorite, hydroxyl hectorite, boron fluorophlogopite, fluorophlogopite, hydroxyl boron phlogopite, and their combination with talc, fluortalc, polylithionite, fluorophlogopite, Complete or complete crystals consisting of water-swellable mica of substantially lithium and/or sodium selected from the group of solid solutions with structurally similar substances selected from the group of polylithionites, phlogopites, and fluorophlogopites. (b) contacting the crystalline body with a polar liquid (usually water) to cause the crystalline body to swell and disintegrate (accompanied by the formation of a gel); and (c) adjusting the ratio of solid content to liquid content of the gel to a desired value depending on the application. Glass-ceramics are desirable crystalline starting materials. These products are then contacted with a large cation source, i.e. an ion source with a larger ionic radius than the lithium cation, resulting in large flocculations of the gel and the formation of crystals with those large cations. Li ⁺ from the middle layer
and or Na ⁺ ions to cause an ion exchange reaction. Further, U.S. Patent Nos. 3,325,340 and 3,454,917 disclose that each carbon group has 3 to
Alkylammonium cations having 6 carbon atoms, and (2) cationic forms of amino acids such as lysine, and ornithine, and/or (3)
The preparation of an aqueous dispersion of swollen permiculite flake crystals due to the introduction of interstitial ions such as lithium is taught. Problem to be solved by the invention Paper produced by the above-mentioned prior art method;
Although articles such as sheets and films exhibit excellent heat resistance and are extremely useful in a wide range of applications, their strength decreases when exposed to high humidity environments or submerged in water or other polar liquids. It exhibits water sensitivity, which is generally exhibited by articles with significant loss of water and deterioration of mechanical and electrical properties. This water sensitivity reduces the effectiveness of these articles in some applications, such as head gaskets, electrical insulators, environmental protection coatings, and cleanable and environmentally stable building materials. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high temperature, fire-resistant, non-asbestos, water-resistant article which has significantly better mechanical and electrical properties than prior art articles. According to the present invention, sheets, paper, paperboard, films,
High temperature, fire-resistant, non-asbestos, water-resistant products such as textiles and coatings are prepared by utilizing exchanged cations selected from guanidine derivatives, swollen, layered, flocculated citrates. It has been discovered that it can be manufactured from gel materials. Surprisingly, the articles were found to exhibit significantly better results in tensile strength and puncture resistance tests when wet than materials prepared utilizing conventional exchange cations. Additionally, articles made according to the present invention generally exhibit superior electrical and mechanical properties than materials made by conventional methods. Regarding heat resistance, articles produced according to the invention are quite stable at temperatures of about 350-400°C and maintain their structural stability up to about 800°C. In one embodiment, the articles of the invention and the flocculated mineral suspensions are prepared by using as starting material a water-swellable silicate having an average charge of about -0.5 to -1 per structural unit. (contains interstitial exchangeable cations that promote swelling). The particular exchange cation in the starting material depends on the silicate utilized. For example, U.S. Pat.
When synthetically derived gelling silicates prepared according to the method of No. 4239519 are utilized as starting materials, the exchange cations are generally Li ⁺ and/or
or Na ⁺ ions. When a natural vermiculite dispersion made according to US Pat. No. 3,325,340 is utilized, the exchange cations generally include the alkyl ammonium cations and other cations specified in that patent. The silicates, whether synthetic or natural, generally have a morphology represented by thin flakes, which are disks, strips or ribbons. Those flakes typically have around 500
~100000 Å, preferably 5000 Å to 100000 Å length, 500 to 100000 Å width, and 100 Å or less thickness. The term "charge per structural unit" as used herein refers to the average charge density as defined by Lagaly and Weiss [G.
A. Weiss, “Determination of Layer Charge
in Mica−Type Layer Silicates”,
Proceedivgs of International Clay
Conference, 61-80 (1969) and G, Lagaly,
“Characterization of Clays by Organic
Compounds”, Clay Minerals, 16 , 1-21
(1981). ]. The starting material silicate is described in the aforementioned U.S. patent no.
No. 4,239,519; No. 3,325,340; and No. 3,434,917 or other methods that provide a dissociation layer material with a charge density within the desired range. The silicate is then contacted with at least one guanidine-derived cation source.
An ion exchange reaction occurs between cations and interstitial ions. This ion exchange reaction takes place between the cation and the silicate material, producing a floc.
This flock is then utilized to form articles of the present invention. In another embodiment of the present invention, the starting material silicate is directly formed into a product such as a lithium fluorohectolite fiber or film by utilizing the method of U.S. Pat. No. 4,239,519. A cation exchange reaction utilizing the guanidine-derived cations is then carried out with the product, for example by soaking the product in a solution of the guanidine-derived cations. Therefore, the ion exchange reaction takes place in situ during the actual production process of the product. The exchange cations utilized in the present invention are derived from compounds corresponding to the formula: R, R ₁ and R ₂ above are selected from -NH ₂ and -CH ₃ respectively, provided that at least two of R, R ₁ and R ₂ are -NH ₂ and R, R ₁ and/or R ₂ One or more hydrogens of C ₁ -C ₅
Can be substituted with substituents such as alkyl, C- _C5 alkenyl, _C1 - _C5 alkynyl, and one or more groups of two of those substituents are optionally attached to form an aromatic ring. A ring like this can be formed. The flocculated mineral suspensions of the present invention can be prepared in a suitable manner, e.g. with stirring, to allow ion exchange between the guanidine-derived cations and interstitial cations to take place in a silicate gel to form exchanged macroagglomerated particles. is prepared by reacting a silicate gel with an exchange cation source derived from a guanidine compound of the formula above. For example, if the exchange cation is guanidium or melanium, the silicate is reacted with the corresponding hydrochloride. As mentioned above, one or more cations derived from the above formula can be utilized in cation exchange reactions. Since different cations provide flocs and end products of different physical properties, the particular cation or mixture of cations is chosen based on the desired end use. The flocculated mineral suspension is used to produce the desired end product. The particular processing steps applied to the flock will depend on the particular article being formed. For example, if the article of the present invention is made into sheet material, the resulting exchange floe is agitated with sufficient shear to obtain a particle size distribution that will lead to proper particle size packing in the sheet forming operation. After this step, the floc is optionally washed to remove excess salt solution and the consistency of the floc slurry is adjusted to about 0.75-2% solids. To increase the rate of dewatering on the Fourdrinier screen, a polyelectrolyte flocculant can be added to the slurry at a floc solids level of about 0.1-1%, preferably 0.2-0.3%. One example of a suitable polyelectrolyte is Polymin P.
(This is BASF's trademark for polyethylene imine). This slurry is then sent to a paper machine where it is dewatered by free dewatering or vacuum dewatering, followed by pressing and drying on a drum dryer. The sheet material thus formed is used for applications such as gaskets. If desired, further inert materials can be added to the flocculated mineral suspension depending on the intended use of the product. For example, if necessary, one or more fiber materials from natural or synthetic organic or inorganic fibers can be selected and used in order to improve the dewatering rate and provide a final product with good strength and handling properties. Can be added to floc. For example, if the final product is a gasket, the fibers of choice are cellulose fibers, glass fibers, and/or Kevlar fibers (Kevlar is a DuPont trademark for aromatic polyamide fibers). Additionally, latex or other binders may be added to the floc to provide a product with superior strength. If the cation exchange reaction is to be carried out directly on the product formed from the silicate starting material, the slurry of the silicate starting material is Add necessary inert materials. The term "water-resistant" herein does not mean that the articles of the present invention are water-resistant or completely impermeable; used to indicate that there is no substantial reduction in tensile strength and puncture resistance. In the examples described below, the starting materials utilized are U.S. Pat. No. 4,239,519, unless otherwise specified.
It was lithium fluorhectorite produced according to the method disclosed in No. EXAMPLE 1 This example describes a method for making a guanidium-exchanged fluorohectolite flocked silicate and sheets prepared therefrom. A slurry of guanidium fluorohectolite is prepared by adding 1.4 liters of 1N guanidine hydrochloride solution to lithium.
It was prepared by adding 475 g of a 10% dispersion of fluorohectolite. The slurry was then agitated in a high shear mixer to reduce the particle size of the resulting floc, washed, analyzed for water content, and diluted to a 2% solids slurry. The resulting slurry was molded into a 29.2 x 29.2 cm hand sheet mold (Williams Apparatus).
(manufactured by the company). The resulting sheet was then wet pressed and dried in a drum dryer. The sheet had good flexibility and showed good gasket seal test results. EXAMPLE 2 This example describes a method for making a film of the invention in which cation exchange is performed in situ. According to the method disclosed in U.S. Pat. No. 4,239,519,
A gelled dispersion of lithium fluorohectolite with a solids content of 10% was prepared. This material is 4.5mil (approx.
The film was prepared using a 0.114 mm applicator (a coating tool capable of drawing a wet film of the dispersion 5 inches wide and 0.114 mm thick onto a glass plate). The glass plate with the film attached is next
It was immersed in a 0.25M guanidium hydrochloride solution to allow cation exchange between the guanidium cations and the intermediate layer cations of fluorohectolite. A skin immediately formed on the surface of the film, indicating that such cation exchange had occurred. After 10 minutes, the film was removed from the glass plate, washed with deionized water to remove residual salts, and dried. The resulting film showed good flexibility and wet strength retention. Examples 3-9 For each of these examples, the method of Example 2 was essentially repeated to produce the corresponding film with the specific exchange cation. In Example 7, a 0.1N melamine hydrochloride solution was used. In all other examples, 0.25N solutions of the respective exchange sources were used as follows: Example Exchange Ion 3 Diaminoguanidine hydrochloride 4 Aminoguanidine hydrochloride 5 Tetramethylguanidine hydrochloride 6 Methylguanidine hydrochloride 7 Melamine hydrochloride 8 Hydrochloric acid 2 , 6-Diaminopyridine 9 2-Aminopyridine Hydrochloride Comparative Examples 1-3 These comparative examples illustrate fluorohectolite films made with various prior art exchange cations. 0.114mm thick potassium fluorhectorite (KFH) and ammonium
Fluorohectolite (NH ₄ FH) received US patent no.
Prepared separately by the method specified in No. 4239519. A film of KFH and NH ₄ FH slurry was then poured. Kymene (for cationic polyamide-epichlorohydrin resin)
Fluorohectolite (trademark of Hercules)
The film was also tested for two reasons: (1) a 3.0% Kymene solution was used, and (2) the lithium fluorohectolite film was diluted in the Kymene solution until the resulting exchanged film was removed from the glass plate and could stand on its own. Prepared by the method of Example 2, except that it was soaked for an hour. These films, along with the films made in Examples 2-9, were then subjected to tensile strength and puncture resistance tests as described below. Tensile Strength Measurements Dry tensile strength measurements were made using an Instron with a jaw spacing of 1.5 inches (3.8 cm) and a crosshead speed of 0.2 inches (0.51 cm)/min. Wet strength measurements were made by contacting a water-saturated sponge to both sides of the film for 10 seconds while the sample was placed in an Instron clamp immediately prior to strength testing. Determination of Puncture Resistance The film test was fixed in a holding device, a needle capable of applying a load was applied to the film in a manner perpendicular to the surface of the film, and the load was increased until the needle penetrated the film. The film in the holder in the wet test was immersed in deionized water for 10 seconds immediately before the puncture resistance test. These test data are shown in the table below.

TABLE The above data show that films made according to the method of the present invention have significantly superior wet tensile strength and superior puncture resistance when compared to conventional compositions. Fire resistance and smoke resistance The film made according to Example 2
Fire and smoke resistance tests were conducted according to the methods specified in ASTM-E-662-79. Three different tests were conducted and the results are shown below. These numbers correspond to the maximum optical density according to National Bureau of Standards Technical Note No. 708. Flame Combustion Smoldering Test No. DM Corr DM Corr 1 2 0 2 1 0 3 1 0 Electrical Properties The films of Examples 2 and 7 and Comparative Example 7 were dried and their dielectric strength was tested using the method of ASTM-D149. did. The results are shown in the table below. Film dielectric strength (V/mil) ^* Example 2 5000 Example 7 9000 Comparative example 3 2920 *1mil≒0.025mm Comparative examples 4 and 5 Figure 2 shows the use of silicate materials which are outside the scope of the invention in measured values. In Comparative Example 4, a 10% aqueous dispersion was prepared from natural hectorite obtained from the American Clay Minerals (Bloomington, Indiana) clay mineral repository. In Comparative Example 5, sodium montmorillonite obtained from the same source was used to
% aqueous dispersion was made. In each comparative example, the film was drawn using the method set forth in Example 2. The glass plate with that film is then
It was immersed in 0.25M guanidine hydrochloride solution for 10 minutes.
In both cases no coherent film was obtained. Example 10 This example illustrates the preparation of a film of the invention using vermiculite starting material. of n-butylammonium vermiculite prepared by the method specified in U.S. Pat. No. 3,325,340.
A 10% solids suspension was cast as a film onto a glass plate according to the method set forth in Example 2. The glass plate with the film attached was immersed in a 0.25M guanidium hydrochloride solution for 10 minutes. The resulting film was removed from the glass plate, washed and dried. The film exhibited wet strength in tensile strength and puncture resistance tests that similar non-cation exchanged vermiculite films did not exhibit. Example 11 This example illustrates the production of fibers using the method of the present invention. A 15% solids suspension of lithium fluorhectorite was extruded through a needle with an 11 mil opening into a 2N guanidium hydrochloride solution. The extruded fibers were supported by a porous belt and sent to a second 2N guanidine hydrochloride bath. The fibers thus prepared were washed by soaking in deionized water and dried. The resulting fibers were strong and flexible.

Claims (1)

Claims: 1. A swollen, layered, silicate gel having an average charge of about -0.5 to -1 per structural unit and containing exchangeable interstitial ions with at least one guanidine-derived cation. A flocked mineral that can be used to form a water-resistant, non-asbestos high-temperature article comprising the step of contacting an ion-exchange reaction between exchangeable interstitial ions and at least some guanidine-derived cations. Method of manufacturing the material. 2. The method according to claim 1, wherein the gelling, layered silicate is a synthetic, gelling silicate, and the interstitial ions are Li ⁺ and/or Na ⁺ . Method. 3 The synthetic silicates include fluorohectolite, hydroxyl hectorite, boron fluorophlogopite, hydroxyl hectorite,
and solid solutions thereof, and talc with these,
An object consisting essentially of crystals of water-swellable mica selected from the group of solid solutions with structurally similar substances selected from the group of fluorotalc, polylithionite, fluoropolylithionite, phlogonite and fluorophlogonite. 3. A method according to claim 2, characterized in that the method is prepared by contacting a polar liquid with a polar liquid for a time sufficient to cause swelling of the crystals with formation of a gel. 4. The method according to claim 3, wherein the crystal is fluorohectolite. 5. The method according to claim 3, wherein the polar liquid is water. 6. The method according to claim 1, characterized in that the silicate is vermiculite and the interstitial ions are alkylammonium cations, amino acid cations and/or Li ⁺ . 7. A method according to claim 2 or 6, characterized in that the guanidine-derived cation is selected from the group of diaminoguanidine, tetramethylguanidine, guanidine, aminoguanidine, methylguanidine and melamine derivatives. 8. A flocked mineral material characterized in that it consists of a swollen, layered, silicate gel having an average charge of about -0.5 to -1 per structural unit and containing at least some interstitial cations that are guanidine derivatives. 9. A flocked mineral material according to claim 8, characterized in that said silicate is synthetically derived. 10 The silicates include (1) fluorohectolite, hydroxyl hectorite, boron fluorophlogopite, hydroxyl boron phlogopite, solid solutions thereof, and talc, fluorothalc, polylithionite, fluoropolymers. Crystals of water-swellable mica selected from the group of solid solutions with structurally similar substances selected from the group of lithionite, phlogopite and fluorophlogopite, and containing interstitial cations of lithium and/or sodium. (2) contacting an object consisting essentially of a polar liquid with a polar liquid for a period sufficient to cause swelling of the crystals with formation of a gel; Prepared by bringing into contact an ion exchange reaction between at least some lithium and/or sodium cations and at least some guanidine-derived cations. 9
Flocked mineral materials as described in Section. 11. The flocked mineral material according to claim 10, wherein the crystal is fluorohectolite. 12. The flocked mineral material according to claim 10, wherein the polar liquid is water. 13. The flocked mineral material according to claim 8, wherein the silicate is vermiculite. 14 The interstitial cations that are guanidine derivatives include diaminoguanidine, tetramethyl guanidine, guanidine, aminoguanidine, methyl guanidine,
14. Flocked mineral material according to claim 9 or 13, characterized in that it is selected from the group of guanidine and melamine derivatives. 15. A high temperature, water-resistant article prepared from a swollen, layered silicate having an average charge of about -0.5 to -1 per structural unit and containing at least some interstitial cation that is guanidine. . 16. High temperature according to claim 15, characterized in that it is prepared from silicate flocs.
Water resistant product. 17. The high temperature and water resistant product according to claim 15 or 16, which is a sheet material. 18. The high temperature and water resistant product according to claim 15 or 16, which is a fiber. 19. The high temperature and water resistant product according to claim 15 or 16, which is a film. 20 has a charge of about -0.5 to -1 per structural unit,
Gellable, layered, with exchangeable interstitial ions
The article made from the water-swellable silicate is contacted with at least one source of guanidine-derived cations to effect an ion exchange reaction between at least some of the guanidine-derived cations and at least some of the interstitial ions. A method for producing a water-resistant, high-temperature silicate product, comprising the steps of: