FR2547239A1 - FLAME-RESISTANT SHEET PAPER AND LAMINATE COMPRISING THE SAME - Google Patents

Abstract

THE OBJECT OF THE INVENTION A PAPER RESISTANT TO FLAME, USEFUL IN THE FORMATION OF DECORATIVE AND INDUSTRIAL LAMINATES FREE OF ASBESTOS. SUCH PAPER CONSISTS OF A CONTINUOUS BAND FORMED FROM AN INCOMBUSTIBLE MINERAL FILLER, AN ORGANIC FIBER AND, OPTIONALLY, A BINDER AND AN INCOMBUSTIBLE FIBER, THE BAND IS IMPREGNATED WITH A RESIN SUCH AS A RESIN PHENOL-FORMALDEHYDE OR AN AMINE-FORMALDEHYDE RESIN. THE PAPER IN QUESTION IS NORMALLY LAMINATED WITH OTHER LAYERS OF THE SAME PAPER OR OF A DIFFERENT PAPER AND USED AS A LAMINATE CORE, DECORATIVE MATERIAL AND OR PAPER INTENDED TO FORM USEFUL PRODUCTS FOR A WIDE NUMBER OF APPLICATIONS IN THE LAMINATE FIELD DECORATIVE AND INDUSTRIAL, WHERE A FLAME RESISTANCE IS NECESSARY.

Description

The subject of the invention is a paper, one of which

  uses consists of the formation of laminates resistant to flame.

  A conventional decorative laminate consists of a core of several phenolic resin impregnated laminated paper sheets and decorative and lamination paper sheets impregnated with a melamine-formaldehyde resin. These laminates have a large number of uses including as office veneers, tables 10 and other furniture and as wall coverings They are often used in interiors of boats and aircraft where it is particularly important that they be flame retardant to prevent the spread of fire in the event of a disaster. One way that has been frequently used in the past to make flame-resistant decorative laminates is to form the core laminate from a raw material of asbestos fibers In cases where asbestos is undesirable Various attempts have been made to develop a flame-resistant asbestos-free laminate core raw material. U.S. Patent Nos. 3,383,267 and 3,647,595 disclose a flame-resistant asbestos-free laminate core material. laminate formed by impregnating kraft paper with an amine phosphate-containing phenol-formaldehyde resin as a flame retardant. US Patent No. 4,288,491 discloses a laminate core material similar to the US Pat. The flame retardant is the reaction product of an aluminum or copper compound with acid.

phosphoric and nitrogenous bases.

  The laminate core materials of the prior art have a number of disadvantages. In some cases, the combustibility index of the laminate core material may be too high. In other cases, the ability of the core web to impregnate with resin (absorption) may not be sufficient to form a strongly bonded laminate. particularly disadvantageous feature of most previous laminate core materials is that the composition from which the paper sheet

  is formed is not compatible with conventional papermaking processes to facilitate the manufacture of the laminate core material.

  Thus, an object of the invention is to provide a flame resistant paper having the required physical and mechanical properties (eg, strength, absorption, heat and flame resistance, etc.) and which is more compatible with techniques

paper manufacturing.

  The invention proposes a paper comprising a strip impregnated with a resin, this strip being characterized in that it is formed of approximately 15 to 90% of an incombustible mineral filler, approximately 5 to 30% of an organic fiber , and up to about 20% of a binder. Unless otherwise indicated, all percentages are by dry weight. According to an advantageous embodiment, up to 30% of a non-combustible fiber is added to the composition of the strip to communicate the burning resistance to the paper. mentioned above can be used in the formation of decorative laminates as one or more of the layers of the core or as a decorative sheet. It has been found that the paper according to the invention has properties

  suitable for printing, especially after it has been calendered.

  The invention also proposes laminates in

  wherein the above mentioned paper constitutes at least one layer and in particular at least one of the outer layers or one of the layers immediately below the decorative and / or coating sheets.

  The inorganic filler component of the paper according to the invention may be any non-combustible inorganic granule which improves the flame retardant properties of the material. Representative examples include all types of clays (eg, bentonite and kaolin), wollastonite, talc, silica, alumina, mica, hydrated alumina, vermiculite (preferably exfoliated), diatomite, etc. Of these, mica alone

  or in combination with vermiculite is advantageous.

  The combination of mica and vermiculite is advantageous because it gives a good control of the density and

the absorption capacity.

  The mineral filler must have particles of such dimensions that they can be dispersed

  homogeneously in the dough and retained by the paper.

  The size of the vermicular granules may range from a fine powder to coarse grains, for example 100% passing through a screen of 0.297 mm mesh aperture.

  % passing through a screen of 44 pn of mesh opening.

  A larger grain vermiculite can be used if the feed is milled into smaller sized particles during the formation of the dough. The smaller particle size tends to undesirably reduce the water absorption capacity. mica particle size is less than that of vermiculite and can range from 100% through a 0.297 mm to 100% sieve through a 44 μm screen of mesh size. The best results were obtained using a mica 74 pm and vermiculite N 4

(60-90% exceeding 0.297 mm).

  The amount of inorganic filler in the paper can be set in a range of about 15 to 90% depending on the fire code specifications that must be met. Similarly, the amount of organic fiber in the paper It can be set in the range of about 5 to 30%. The amounts of filler and organic fiber are generally harmonized to adjust the balance between flame resistance and mechanical strength at loading levels of the product. order of 90%, the paper is very resistant to flame but has a low tensile strength As the amount of organic fiber increases, the strength of the paper improves but the flame resistance decreases because The greater content of organic matter in the raw material has been found to be desirable for most applications to use from about 9 to 20% of organic fiber with about 75% of the organic material. at

% of charge.

  Virtually any organic fibrous material commonly used in the manufacture of fibrous or water-formed webs can be used in the manufacture of the paper of the invention. Representative cellulosic fibers and synthetic organic fibers are included in the representative examples of useful fibers. such as acrylic fibers, regenerated cellulose, polyesters, phenolic fibers and the like. Cellulosic fibers having fine and strong fibers providing good strength and retention characteristics are advantageous, such as those obtained in

  a kraft pulp made from northern conifers.

  It is also desirable to include mineral fibers in the paper to increase the resistance to combustion; That is, to prevent a laminate based on this paper from breaking up when the organic component has been burned. The glass fibers are advantageous mineral fibers, but ceramic fibers, zirconia-silica fibers, whiskers crystalline alumina, alumina silicate fibers, metal filaments, etc. can also be used These fibers can be used in sheet paper in amounts of up to 30% and do not need to If the resistance to burning is not important, the length of the fibers used is generally in the range of about 0.5 to 1 cm and the diameter of the fibers in the range of about 8 to 1 cm. at 12 micrometers Larger fibers are more difficult to disperse and

  smaller fibers are more expensive.

  paper strip in conventional drying ovens or drums When the strip paper is to be printed, it is advantageous to calender it It may be desirable to refine the material constituting the organic fiber before the addition of the mineral filler since After the addition of the mineral filler, wear of the apparatus and problems of handling the processed pulp may occur. One means which has been used is to add the fiberglass to the refined cellulose fiber and to mix the fibers with filler and binder in a dough chest The dough is usually mixed so that it has a consistency of about 1% when placed on the alum paper machine, holding aids , moisture resistant resins and / or other additives may be added to the composition of

  paper in a conventional manner according to the desired properties.

  The capacity of the strip with respect to the impregnating resin (absorption) can be adjusted by acting on various factors such as the nature of the filler, the degree of compression of the strip, and the degree of refining of the cellulosic fibers. It is desirable for most uses to make a paper having a resin absorption capacity of about 25 to 60% based on the total weight of the resin impregnated paper If the resin absorbency is too low, the laminate formed from the

  paper may not have good structural integrity.

  High resin absorption capacity is functional but not necessary and leads to consumption

  needless resin in many cases.

  The desired resin absorbency is dependent upon the use of the paper either as a core laminate, or as a decorative laminate or as a coating. When impregnated with a phenol-formaldehyde resin, 25 to 35% of solid resin The impregnated paper is desirable for a core laminate. When impregnated with a melamine-formaldehyde resin, it may be desirable for a decorative sheet to have a desired content of 50 to 55%. The presence of a binder may be desirable. optional, but it is included in the sheet paper forming composition to add strength and retain the load so that it is not lost during manufacture All current and preferably flame resistant latexes and binders used Classically in the manufacture of paper can be used in the invention Some representative examples of binders and latex resistant to flamm e are the following: halogen-containing organic polymers such as polyvinylidene chloride, polyvinyl chloride, a copolymer of ethylene and vinyl chloride, neoprene, and copolymers of the monomers forming the polymers mentioned above with vinyl acrylate, vinyl acetate, styrene, butadiene, acrylonitrile, etc. Polyvinylidene chloride is preferred. Representative examples of suitable but non-flame resistant binders include starch, polyvinyl alcohol copolymer, acrylic polymers, copolymers of ethylene and vinyl acetate, styrene-butadiene rubber, acrylonitrile-butadiene rubber, natural rubber, and the like. The amount of binder is not particularly critical. It is usually employed in an amount of up to 20% (solids). If the paper is prepared without a binder, it is desirable to use more organic fibers for additional strength. (for example,

about 20 to 50%).

  The paper according to the invention is made using conventional paperboard or paperboard production techniques. In general, the steps used in forming the paper sheet are: (i) mixing the ingredients of the manufacturing (ie, fiber, mica and binder) in batteries, mills, or pulp bins common in papermaking; (ii) forming the web on a wet round machine, a conventional cardboard round machine or Fourdrinier machine, and (iii) drying the machine.

254 '7239

  to use other resins under different conditions.

  It is advantageous that the papers of the invention provide a resin penetration rate of less than about 40 seconds when they constitute the thickness of the laminate core material and less than about 20 seconds when they constitute the thickness of the sheets. This speed is measured by floating a sample of the paper on a resin reservoir (e.g., a solution of Monsanto 841 in water and methanol (50/50) having a viscosity of 92 m Pa s). at 25 C and in

  measuring the time needed for the paper to be soaked.

  The tape can be impregnated with any resins

  typically used as impregnating resins in the formation of flame resistant decorative laminates.

  The resin is used for interlaminar strength and to provide a wear-resistant hard material. Thermosetting or thermoplastic resins may be used. Representative examples of thermosetting resins suitable for use according to the invention are phenol-formaldehyde resins, resins and the like. amine-formaldehyde, urea-formaldehyde resins, melamine-formaldehyde resins as well as

  epoxy resins, polyester resins, vinyl acetate copolyamines, acrylic resins, and the like.

  It is advantageous to use thermosetting resins which carbonize upon exposure to flame or intense heat. Phenolic resins such as phenol-formaldehyde copolymers and amine formaldehyde resins are often used. also useful, including halogenated polymers such as polyvinyl chloride, polyvinylidene chloride, copolymers

  ethylene and vinyl chloride and the like.

  The impregnation is carried out in a representative manner by immersing the dry paper in a resin bath and holding it in the bath until it has absorbed the desired resin content. After the impregnation, the For example, leaves are dried or cooked to a stage B, assembled in a notebook with a decorative layer above and laminated in a press. Examples of laminates include 2 to 6 layers of paper impregnated with a phenol-formaldehyde resin and one or two decorative sheets and / or paper-coating sheets impregnated or coated with an amine-formaldehyde resin. inven10 tion can be printed with acceptable quality, impregnated with resin and used as decorative sheets in the laminate The print quality is strongly

  improved when the paper was calendered.

  According to fire code specifications which must be satisfied, the decorative laminate may be formed wholly or in part from layers of the paper according to the invention. To satisfy stricter fire code requirements, the decorative laminate In addition, to meet less stringent specifications, the laminate may consist of one or more layers of the paper according to the invention and one or more layers of the paper according to the invention. several layers of resin impregnated kraft paper, eg phenol-formaldehyde impregnated kraft paper, or paper

  ordinary decorative resin saturated with an amine-formaldehyde resin.

  The invention is illustrated in more detail below

  with reference to the following examples which are not limiting.

EXAMPLE 1

  A sheet paper was prepared by introducing 180 parts of expanded N 4 vermiculite, 645 parts of Suzorite mica (74 m) (a product of Martin Marietta Corp), 30 parts of 6.35 mm cut fiber (Owens). Corning 35 Cor "', 90 parts of refined kraft fiber of northern conifers and 55 parts (in solids) of polyvinylidene chloride and 12,000 to 35,000 parts of water in a battery case to obtain a paste having a consistency of about 3 to 8% This raw material was diluted to a consistency of about 0.5 to 2.0% and placed in a wet state on a Fourdrinier paper machine, followed by a wet treatment and drying on steam heated tumble dryers The resulting flame retardant paper was sent to a resin treatment apparatus where it was impregnated with phenol formaldehyde resin. and cooked to a stage B to give a

  sheet of material for laminate core according to the invention.

  The obtained laminate core material was flame retarded by placing its bottom edge 25.4 mm above a Bunsen burner with a 50.8 mm flame for 15 seconds and revealed

  have self-extinguishing properties.

EXAMPLE 2

  A strip was produced in a manner similar to that of Example 1, except that it consisted of 730 parts of mica, 30 parts of 6.35 mm cut fiberglass, 40 parts ( solids) of polyvinylidene chloride Q, and 200 parts of cellulose fiber The strip paper was impregnated with a phenol-formaldehyde resin and flame-proofed as in Example 1 The sheet featured

self-extinguishing properties.

  Although the product described herein is a preferred embodiment of the invention, it should be understood that the invention is not limited to this particular product, and that changes can be made without it.

depart from the scope of the invention.

Claims (15)

  A paper comprising a flame-resistant continuous web containing a non-combustible mineral filler, said web being impregnated with a resin, characterized in that said web is formed from a composition comprising about 15 to 90 wt. a mineral filler, about 5 to 30% of an organic fiber and from O to about 20% of a binder.   2 Paper according to claim 1, characterized in that said mineral filler is selected from the group   comprising mica, expanded vermiculite, unexpanded vermiculite, clay, wollastonite, talc, silicate, hydrated alumina and mixtures thereof.   Paper according to claim 1, characterized in that said binder is selected from the group consisting of polyvinyl chloride, polyvinylidene chloride,   a copolymer of ethylene and vinyl chloride, neoprene and their copolymers.   A paper according to claim 1, characterized in that said web further comprises a non-combustible mineral reinforcing fiber, preferably fiber of glass.   Paper according to claim 1, characterized   in that said inorganic filler comprises mica, ver-miculite or their mixture, preferably mica.   Paper according to claim 1, characterized   in that said impregnating resin is a phenol formaldehyde resin or an amine-formaldehyde resin.   Paper according to claim 4, characterized in that said web is formed from a composition which comprises mica, vermiculite or their mixture as mineral filler, a halogen-containing organic binder, cellulose fiber, and glass fiber, said inorganic filler preferably being present in an amount of about 75 to 85% by weight, said binder preferably being present in an amount of about 2 to 10% by weight, said fiber being cellulose being preferably it   present in an amount of about 9 to 20% by weight and said glass fiber is preferably present in an amount of from 0 to 20% by weight.   8 Paper according to claim 7, characterized in that said incombustible mineral filler is made of mica.   Paper according to claim 8, characterized in that said impregnating resin is a phenol-formaldehyde resin.   A multi-layered laminate, at least one of which is a paper which comprises a flame resistant web containing a non-combustible and resin impregnated mineral filler, characterized in that said web is formed from a composition comprising about 15 to 90% by weight of a mineral filler, about 5 to 30% of an organic fiber and from 0 to about 20% of a binder.   A laminate according to claim 10, characterized in that said mineral filler is selected from the group consisting of mica, expanded vermiculite, unexpanded vermiculite, clay, wollastonite, talc, silicate, alumina huddrate and their mixtures.   Laminate according to claim 10, characterized in that said binder is selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, a copolymer of ethylene and vinyl chloride, neoprene and their copolymers.   Laminate according to claim 10, characterized in that said strip further comprises an incombustible reinforcing fiber, preferably a glass fiber.   Laminate according to Claim 10, characterized in that the said mineral filler consists of mica, vermiculite or a mixture thereof, preferably mica.   A laminate according to claim 10, characterized in that said impregnating resin is a phenol-formaldehyde resin or an amine-formaldehyde resin.   A laminate according to claim 13, characterized in that said web is formed from a composition which comprises mica, vermiculite, or a mixture thereof, an organic halogen-containing binder, cellulose fiber and fiber of glass. Laminate according to claim 16, characterized in that said incombustible mineral filler is made of mica and said impregnating resin is of   preferably a phenol-formaldehyde resin.   Laminate according to claim 10, characterized in that said layer constitutes at least one face said laminate.   Laminate according to claim 10, characterized in that said layer is a decorative sheet.