Fibrous sheet materials

• US 4,248,664 A
• Filed: 06/13/1979
• Issued: 02/03/1981
• Est. Priority Date: 06/20/1978
• Status: Expired due to Term

• Current Assignee: T&N Materials Research Limited
• Original Assignee: Turner & Newall Limited
• Inventors: Atkinson, Alan W., Lancaster, Robert A., Clucas, Richard H., Perkins, Allen M.
• Primary Examiner(s): Chin, Peter
• Application Number:
  US06/048,017
• Time in Patent Office: 601 Days
• Field of Search: 162/145, 162/152, 162/175, 162/181 D, 162/156, 106/8 S, 106/288 B
• US Class Current: 162/145
• CPC Class Codes: C04B 14/10 Clay sepiolite C04B14/042; grog C04B18/025
• CPC Class Codes: C04B 14/38 Fibrous materials; Whiskers
• CPC Class Codes: C04B 18/241 Paper, e.g. waste paper; Paper pulp
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 30/02 containing fibrous materials
• CPC Class Codes: D21H 13/40 vitreous, e.g. mineral wool, glass fibres
• CPC Class Codes: D21H 17/68 siliceous, e.g. clays
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

A board product containing glassy inorganic fibre such as mineral wool, in a matrix of a plastic clay such as ball clay. The amounts of clay and inorganic fibre are in the respective ranges 29 to 80 percent by weight and 15 to 55 percent by weight of the product, and its density is at least 500 kg/m³.

The board can replace asbestos millboard and has the advantage of being asbestos-free. It can be made by the standard paper and board-making techniques, when preferred ingredients are pulp fibres e.g. cellulose pulp, and a complementary binder, particularly hydrolyzable starch, the latter enabling the product to be re-mouldable upon moistening with water.

Claims

1. In a process for the production of a non-combustible asbestos-free board product comprising a matrix of ball clay reinforced with glassy inorganic fiber, including the steps of:

(i) dewatering on a sieve or other filter medium an aqueous suspension containing glassy inorganic fiber and ball clay as the major ingredients, with a small proportion of starch as binder, and

(ii) subsequently setting the dewatered suspension at elevated temperature, the improvement which consists in;

(a) employing as the aqueous suspension one which has a higher content of ball clay than of glassy inorganic fiber and which also contains organic web-forming fibers, the proportions of the various ingredients by weight of total solids in the suspension being;

space="preserve" listing-type="tabular">______________________________________ unfired ball clay 42-67% glassy inorganic fiber 18-42% starch 1.5-5% organic web-forming fiber up to 7% ______________________________________

in combination with

(b) limiting the setting at elevated temperature to a drying procedure which is carried out

(b1) until the board product has a tensile strength greater than 2 MPa and a density at least 500 kg/m³ but less than 1200 kg/m³, and

(b2) so as to leave the ball clay in the unfired state and the starch content in the range 1.5-5% by weight, to obtain a board product which is remoldable when rewetted with water.

2. A process according to claim 1, in which said aqueous suspension contains 42-62% by weight of unfired ball clay, and 23-42% by weight of glassy inorganic fiber.

3. A process according to claim 1, in which the glassy inorganic fiber is mineral wool.

4. A process according to claim 1, in which the organic web-forming fiber is cellulose fiber.

5. A process according to claim 1, in which the starch is farina starch.

6. A process according to claim 1, in which said aqueous suspension contains bentonite clay in an amount up to 5% by weight of total solids.

7. A process according to claim 1, in which said aqueous suspension contains mica in an amount of about 5% by weight of total solids.

8. A non-combustible asbestos-free board product having a matrix of a plastic clay reinforced with a glassy inorganic fiber and remoldable when wetted by water produced by the process of claim 1.