초록 ▼

A method of forming a gypsum-based panel product including the steps of: mixing calcined gypsum, water, a foaming agent and a core strengthening agent to form a foamed slurry; depositing the slurry; shaping the slurry to form a board having a core and core surfaces, optionally sandwiched between she

A method of forming a gypsum-based panel product including the steps of: mixing calcined gypsum, water, a foaming agent and a core strengthening agent to form a foamed slurry; depositing the slurry; shaping the slurry to form a board having a core and core surfaces, optionally sandwiched between sheets of liner; and allowing the core to set, and drying the board, wherein the strengthening agent is dextrin, used in an amount not less than 0.1% by weight, based on the amount of calcined gypsum, so that, after drying, there is provided a strengthening dispersion of dextrin throughout the core. Less than 5% dextrin in preferred.

대표청구항 ▼

The invention claimed is: 1. A method of forming a gypsum-based panel product including the steps of: mixing calcined gypsum, water, a foaming agent and a core strengthening agent to form a foamed slurry; depositing the slurry; shaping the slurry to form a board having a core and core surfaces, opt

The invention claimed is: 1. A method of forming a gypsum-based panel product including the steps of: mixing calcined gypsum, water, a foaming agent and a core strengthening agent to form a foamed slurry; depositing the slurry; shaping the slurry to form a board having a core and core surfaces, optionally sandwiched between sheets of liner; and allowing the core to set, and drying the board, wherein the strengthening agent is non-pregelatinized dextrin formed by thermal degradation, used in an amount not less than 0.1% by weight, and in an amount not more than 1.2% by weight, based on the amount of calcined gypsum, so that, after drying, there is provided a strengthening dispersion of dextrin throughout the core. 2. A method according to claim 1 wherein the strengthening agent is used in an amount not less than 0.3% by weight, based on the amount of calcined gypsum. 3. A method according to claim 1, wherein the resultant panel has a nail pull resistance at least 4% greater than that of a panel formed by the same method but without the strengthening agent. 4. A method according to claim 1, wherein the resultant panel has a nail pull resistance at least 6% greater than that of a panel formed by the same method but without the strengthening agent. 5. A method according to claim 3, wherein the resultant panel has a core compressive strength not less than that of a panel formed by the same method but without the strengthening agent. 6. A method according to claim 1 wherein the dextrin is derived from one of corn, wheat, tapioca, potato, rice, sago and sow gum. 7. A method according to claim 1 wherein the dextrin is added to the slurry in the form of granules. 8. A method according to claim 1 wherein the dextrin has composition in which the amount of amylopectin is 70% or more, based on the total amount of dextrin. 9. A method according to claim 1, wherein a liner is applied to at least one of the core surfaces and the resultant plasterboard has a liner-core bond strength not less than that of a plasterboard formed by the same method but without the strengthening agent. 10. A method according to claim 9 wherein a paper-core bonding agent is added to the slurry, the paper-core bonding agent being different from the strengthening agent. 11. A method according to claim 10 wherein the paper-core bonding agent migrates towards the paper-core interface during processing of the plasterboard to a greater extent than the core strengthening agent. 12. A method according to claim 11 wherein the paper-core bonding agent is an acid-modified or oxidised starch. 13. A method according to claim 10 wherein the paper-core bonding agent is added to the slurry in an amount not less than 0.1% by weight and not more than 1% by weight, based on the amount of gypsum. 14. A method according to claim 13 wherein the paper-core bonding agent is added to the slurry in an amount not more than 0.5% by weight, based on the amount of gypsum. 15. A method according to claim 10 wherein the sum of the amount of paper-core bonding agent and core strengthening agent is less than 1.5% by weight, based on the amount of gypsum. 16. A method according to claim 1 wherein the panel product is produced in a continuous process, the slurry being deposited onto a moving conveyor. 17. A gypsum-based panel product having a core comprising at least partially hydrated calcined gypsum and a strengthening agent, the core having voids formed therein, the core optionally being sandwiched between sheets of liner, wherein the strengthening agent is non-pregelatinized dextrin formed by thermal degradation, used in an amount not less than 0.1% by weight, and in an amount not more than 1.2% by weight, based on the amount of calcined gypsum, the dextrin being distributed in the core so that there is provided a strengthening dispersion of dextrin throughout the core. 18. A gypsum-based panel product according to claim 17 comprising not less than 0.3% by weight of strengthening agent, based on the amount of calcined gypsum. 19. A gypsum-based panel product according to claim 17 having a liner applied to at least one of the core surfaces. 20. A gypsum-based panel product according to claim 19 further comprising a paper-core bonding agent, the paper-core bonding agent being different from the strengthening agent. 21. A gypsum-based panel product according to claim 20 wherein the paper-core bonding agent is an acid-modified or oxidised starch. 22. A gypsum-based panel product according to claim 20 wherein the paper-core bonding agent is present in the plasterboard in an amount not less than 0.1% by weight and not more than 1% by weight, based on the amount of gypsum. 23. A gypsum-based panel product according to claim 20 wherein sum of the amount of paper-core bonding agent and core strengthening agent is less than 1.5% by weight, based on the amount of gypsum. 24. A gypsum-based panel product according to claim 17 wherein the core has a notional centre line, equispaced between the surfaces of the panel, a central region of the panel being defined as a band extending to two thirds of the thickness of the core and centred on the centre line, wherein, of the total amount of dextrin detectable in a cross section of the finished product, at least 50% is located in said central region of the panel. 25. A gypsum-based board product according to claim 24 including a paper-core bonding agent, wherein peripheral regions of the panel are defined as: a first peripheral region of the plasterboard being defined in a band extending parallel to and incorporating one board surface and being 10% of the thickness of the board; a second peripheral region of the plasterboard, at the opposite side of the plasterboard from the first peripheral region, said second peripheral region being defined in a band extending parallel to and incorporating the other board surface and being 10% of the thickness of the board; wherein at least 50% of the total amount of paper-core bonding agent present in the board is located in the first and second peripheral regions of the board. 26. A gypsum-based board product according to claim 24 including a paper-core bonding agent, wherein at least 75% of the total amount of paper-core bonding agent present in the board is located in the first and second peripheral regions of the board.