EP0187821A1 - Feuille de mica de haute densite resistant a l'humidite - Google Patents

Feuille de mica de haute densite resistant a l'humidite

Info

Publication number
EP0187821A1
EP0187821A1 EP85903569A EP85903569A EP0187821A1 EP 0187821 A1 EP0187821 A1 EP 0187821A1 EP 85903569 A EP85903569 A EP 85903569A EP 85903569 A EP85903569 A EP 85903569A EP 0187821 A1 EP0187821 A1 EP 0187821A1
Authority
EP
European Patent Office
Prior art keywords
mica
polysiloxane
naphthenate
titanate
binder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85903569A
Other languages
German (de)
English (en)
Other versions
EP0187821A4 (fr
Inventor
Arthur F. Doyle
Dennis J. Sklarski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Essex Solutions USA LLC
Original Assignee
Essex Group LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Essex Group LLC filed Critical Essex Group LLC
Publication of EP0187821A1 publication Critical patent/EP0187821A1/fr
Publication of EP0187821A4 publication Critical patent/EP0187821A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B19/00—Layered products comprising a layer of natural mineral fibres or particles, e.g. asbestos, mica
    • B32B19/02—Layered products comprising a layer of natural mineral fibres or particles, e.g. asbestos, mica the layer of fibres or particles being impregnated or embedded in a plastic substance
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/36—Inorganic fibres or flakes
    • D21H13/38—Inorganic fibres or flakes siliceous
    • D21H13/44—Flakes, e.g. mica, vermiculite
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/59—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30—Multi-ply
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/72—Density
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
    • B32B2309/02—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
    • B32B2309/12—Pressure

Definitions

  • the field of art to which this invention pertains is mica containing composite material.
  • Mica containing articles have been used for many years as electrical insulating structures or for thermal insulation.
  • such mica articles are composite structures formed by bonding mica sheeting with a bonding agent such as an alkyd, vinyl or a silicone material.
  • Such articles have good dielectric strength, heat stability and are relatively inexpensive.
  • Such articles are used as supporting insulation, for glowing red hot resistance wire heating elements for use in electric toasters, hair dryers, curlers, etc., high temperature thermostats, control devices, strip heaters and baseboard heaters.
  • they are also used for gaskets and spacers in other electrical appliances.
  • these mica products are susceptible to attack by moisture, are relatively easy to fracture, and are not always uniform in thickness or dimensionally stable at high temperatures.
  • such mica products are not stain resistant and have relatively poor machinability characteristics. Therefore, what is needed in the art is a mica composite material which overcomes such problems.
  • the present invention is directed toward a relatively high density, mica sheet comprising a plurality of mica papers which are impregnated with about 5% to 14% by weight of a polysiloxane binder which contains a titanate and a naphthenate and which has been formed such that the density of the mica sheet is greater than about 1.5 g/cc.
  • a polysiloxane binder which contains a titanate and a naphthenate and which has been formed such that the density of the mica sheet is greater than about 1.5 g/cc.
  • Such mica sheet is also moisture resistant, thermally stable, dimensionally stable, stronger and more stain resistant than that of the prior art.
  • such a material is scouring resistant and has improved machinability and punchability qualities.
  • Another aspect of the invention is a method of forming such sheet material by impregnating mica paper with about 5% to about 14% by weight of a polysiloxane binder which contains a titanate and a metal naphthenate, stacking the impregnated papers on top of each other and densifying and curing the binder under pressure and temperature to form the high density moisture resistant sheets.
  • the mica paper used to practice this invention may comprise any continuous, thin mica paper, however, those made from muscovite or phlogopite mica are preferred. Which material is selected depends on the properties desired in the end product. Typically, where high dielectric properties are desired, muscovite will be used, whereas, if high temperature properties are desired, the phlogopite is generally selected.
  • the mica paper is typically in the form of conventional water-disintegrated, integrated mica paper which may be prepared using conventional techniques. The thickness of the mica paper characteristically ranges from about 2 mils to about 20 mils with about 5 mils being preferred.
  • the binder which is used to form the mica laminate comprises any of the thermally cross-linkable silicone polymer systems which are used to form other mica laminates.
  • the selection of which system to use depends on the properties desired in the final laminate. Since many of the mica laminates find uses in high temperature environments above 359°F (180°C), it is preferred that the binder system used be thermally stable at these elevated temperatures.
  • the preferred systems are the polysiloxane polymers which are conventionally used in this field. The most preferred systems are methyl-phenyl polysiloxane or methyl polysiloxane which are available from Dow Corning Corporation, Midland, Michigan, as Dow Corning 4-3136, Dow Coming 2104 or 2105 or 2106.
  • polysiloxane system used to practice this invention should not condense or outgas excessively while curing, for this may cause the formation of a defective laminate through the formation of blisters or voids in the laminate.
  • Any compatible titanate may be mixed with the polymer system in the range from about 1% to about 4% by weight with about 2% being preferred.
  • the titanates which are most useful are those which are soluble in the polymer system, i.e. polysiloxane, and do not promote rapid cross-linking of the polymer which will shorten the shelf life of the system. Whether a titanate causes too rapid cross-linking or not is dependent on the manufacturing process which is used to form the laminates. A manufacturing process which is fast, may tolerate a faster cross-linking process while a slower process will produce an inferior product.
  • Some typical titanates are listed in Table I, with the preferred titanates being those of the monoalkoxy pyrophosphato titanate family.
  • metal naphthenate driers are added to the base polymer in concentrations from about 0.5% to about 2%, by weight of the polymer, with about 1% being preferred.
  • metallic soap driers are manganese naphthenate, zinc naphthenate, tin naphthenate, cobalt naphthenate, etc. It is believed that the addition ⁇ f these naphthenate driers coupled with the titanate are what give these mica laminates their superior moisture resistant properties.
  • a binder solution containing the above constituents to be applied to the mica paper is typically prepared as follows:
  • Solvent is placed in a container in which the binder will be prepared.
  • solvents are typically aromatic hydrocarbons in which all of the constituents are compatible such as toluene or xylene.
  • the amount of solvent is not critical and is typically in the range of from about 40% to about 60% of the total volume of the solution.
  • the titanate is then added to the solvent and is stirred until the titanate is dissolved and the solution is clear. Typically, this is done at ambient temperatures about 60oF (15oC) to about 85°F (30oC). While the stirring continues, the naphthenate drier is added to the solution and stirred until dissolved. Again, this is done at ambient temperatures. To this solution is then added the polysiloxane and the mixture is stirred until homogenous, typically for about one-half hour to one hour at ambient temperatures The polysiloxane is added in quantities such that the titanate and naphthenate will be in the proper concentrations and the balance of the binder is polysiloxane.
  • the mica paper is removed from the roll and placed on a flat surface, i.e. a table, conveyer belt, etc., and the paper is impregnated with the binder by any conventional technique, i.e. dripping.
  • the amount of the binder applied is such that the final laminate contains about 5% to about 14% by weight binder and the application should be such that the binder is evenly distributed throughout the laminate.
  • Other conventional impregnation techniques may be used to apply the binder to the paper such as dipping, or roll soaking, spraying, brushing, etc., and in certain processes, it may be desirable to coat both sides of the paper.
  • the aromatic solvent present in the binder is then removed by exposing the paper and binder to temperatures high enough to cause the solvent to evaporate, but not so high as to cause the polymer to polymerize. Typically, these temperatures are about 250°F (121°C) to about 275°F (135°C). Typically, this is done by passing the paper through an .oven or exposing it to radiant heat, etc.
  • the solvent free paper is then cut into the desired size and stacked one on top of the other to the desired thickness.
  • Such thicknesses may vary from about 15 mils to about 2 inches or more.
  • the number of layers required to achieve a given thickness will, of course, vary depending on the thickness of the mica paper, as well as the curing pressures.
  • these precured laminates are made to allow for a loss in thickness after densification of about 10% to about 40%.
  • the orientation of the sheets may be in any direction and is not critical.
  • the stack is then placed in a press which is capable of generating pressures of between 100 psi to 1,000 psi or higher, and temperatures of from about 500oF
  • the laminate stack is placed in the press between the two platens. If more than one high density laminate is to be formed during the single curing process, a separator sheet, typically of Teflon®, is inserted between the stacks as they are placed in the press. The laminates are then densified at the predetermined pressure and the binder is cured at or above the polymerization temperatures of the polymer under pressure, during the course of densification.
  • the preferred technique is to heat the platens through either electrical, steam, hot oil or other means to the desired temperature.
  • these laminates are densified at pressures from about 100 psi to about 1,000 psi and temperatures from about 500°F (260°C) to 1000°F (538°C) for about 6-10 hours or until the binder has substantially cured.
  • the laminate is then allowed to cool to about 100oF (37.8°c) or below while still under pressure.
  • the densified mica laminate may then be removed from the press.
  • the particular curing or densifying cycle will vary depending on the binder being used, thickness of the laminate being formed and the temperatures and pressures at which the laminates are subjected.
  • the process will entail slowly raising the laminate to the maximum densification conditions which would allow for any outgassing of the material prior to final densification. This can be done in a step-wise manner or a gradual increase.
  • the cycle should not allow the polysiloxane binder to cure prematurely, preventing the laminate from being fully densified, resulting in an inferior product.
  • these parameters can be controlled by conventional electrical or computer control systems which would interface with the press.
  • the mica laminates formed using the present invention typically range in thicknesses from about 15 mils to about 2 inches and have densities of about 1.5 g/cc to about 2.5 g/cc.
  • a typical mica laminate was prepared from seven sheets of 4 mils muscovite mica paper which has been impregnated with 10% of the polysiloxane binder containing 2% of isopropyl tri (dioctylpyrophosphato) titanate and 1% zinc naphthenate. The impregnated paper was then stacked, one on top of the other, and placed in the press, cured and densified in the following sequence. Apply 500 psi to product
  • Such a mica laminate would be 0.5 mm (0.020") in thickness and have typical properties as follows:
  • the mica laminates prepared using the present method have remarkably and surprisingly different properties than other mica laminates produced in the past.
  • the present laminates have smoother surfaces and significantly greater mechanical strength.
  • the increase in structural integrity makes these laminates more like sheet metal than flaky composites and allows for a much cleaner and neater product with less waste subsequent to the machining operations.
  • these laminates are extremely stain resistant and this very important when one considers that a principal use of such laminates is in microwave ovens which are subject to fumes and food spills.
  • these laminates are capable of being immersed in boiling water intermittently witliout substantially changing their physical properties.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Inorganic Insulating Materials (AREA)
  • Organic Insulating Materials (AREA)

Abstract

Laminé de mica de haute densité, résistant à l'humidité et stable à haute température. Ce laminé comprend une pluralité de papiers de mica, imprégnés avec un liant à base de polysiloxane contenant du titanate et de naphténate. Est également décrit un procédé de préparation de ces laminés de mica. Les laminés ci-décrits présentent des qualités structurales exceptionnelles, sont très résistants à l'humidité et aux taches et ont des densités supérieures ou égales à 1,5g/cm2.
EP19850903569 1984-07-02 1985-07-01 Feuille de mica de haute densite resistant a l'humidite. Withdrawn EP0187821A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US62724484A 1984-07-02 1984-07-02
US627244 1984-07-02

Publications (2)

Publication Number Publication Date
EP0187821A1 true EP0187821A1 (fr) 1986-07-23
EP0187821A4 EP0187821A4 (fr) 1986-07-23

Family

ID=24513837

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850903569 Withdrawn EP0187821A4 (fr) 1984-07-02 1985-07-01 Feuille de mica de haute densite resistant a l'humidite.

Country Status (4)

Country Link
EP (1) EP0187821A4 (fr)
JP (1) JPS61502597A (fr)
BR (1) BR8506821A (fr)
WO (1) WO1986000571A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IN162389B (fr) * 1984-10-22 1988-05-21 Essex Group
EP3819114A1 (fr) 2019-11-06 2021-05-12 COGEBI société anonyme Structures en sandwich à base de mica
CN112590356A (zh) * 2020-12-14 2021-04-02 麦卡电工器材(陆河)有限公司 一种耐高温云母板压制工艺

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2914426A (en) * 1956-08-09 1959-11-24 Gen Electric Method of rendering mica paper moisture resistant and article produced thereby
US2949150A (en) * 1957-07-16 1960-08-16 Westinghouse Electric Corp Flexible bonded mica insulation
US4371579A (en) * 1980-10-09 1983-02-01 Westinghouse Electric Corp. Fire-resistant filler sheet laminates
US4374892A (en) * 1981-06-03 1983-02-22 Essex Group, Inc. Moisture resistant insulating mica tape comprising a monoalkoxy titanate

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8600571A1 *

Also Published As

Publication number Publication date
BR8506821A (pt) 1986-11-25
JPS61502597A (ja) 1986-11-13
EP0187821A4 (fr) 1986-07-23
WO1986000571A1 (fr) 1986-01-30

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Inventor name: DOYLE, ARTHUR, F.

Inventor name: SKLARSKI, DENNIS, J.