MXPA00001953A

MXPA00001953A - Application of polymer in plaster wall slab

Info

Publication number: MXPA00001953A
Application number: MXPA/A/2000/001953A
Authority: MX
Inventors: Hsienhsiang Hsu Oscar
Original assignee: Rohm And Haas Company
Priority date: 1999-03-05
Filing date: 2000-02-24
Publication date: 2001-07-31

Abstract

A composition useful as gypsum wallboard and a method for protecting gypsum wallboard against water are disclosed. The composition and the method utilize a polymer containing C12-C40 alkyl ester of (metho) acrylic acid as hydrophobically modified monomer to provide water resistance.

Description

Use of polymers in gypsum boards The present invention relates to the use of polymers in gypsum boards. The polymers contain hydrophobically modified monomers as polymerized units and are prepared by polymerization of emulsions. Gypsum board is a material commonly used in buildings for walls and ceilings. It is usually a plan board of plaster material lined with paper on both exterior surfaces. ^ _: Gypsum board typically contains calcium sulfate hemihydrate as the main ingredient. When placed on the plaster, a drop of water will be absorbed almost immediately. This can cause problems because the plaster can weaken or water can stain walls or ceilings. Gypsum board can be used in err places where it is exposed to high humidity levels, for example areas with humid climates. Exposure to water is common in rooms such as bathrooms or kitchens, where the steam from the showers can accumulate in the room or the water in the sink can splash on the walls. As an alternative, gypsum board can be exposed to water through leaks in roofs or pipes. Given the problems related to water, There is a need for a gypsum board ~ water resistant. One approach to solving this problem has been to "treat the paper coating with a latex of resin solids mixed with water." This approach has been demonstrated in U.S. Patent No. 5,397,631.The gypsum board having treated paper coating in this way it can usually be easily identified, since "paper coatings tend to be blue or green to indicate that they have been treated. Even though this approach provides some protection against water, water is able to slowly penetrate the treated paper coating and enter the gypsum. Waxes have been used to give the gypsum some water resistance, but it has not been shown that the polymers are useful in this way.When the polymers have been mixed with gypsum, the aim has been to increase gypsum strength. 30515 presents the use of polymers of lower alkyl acrylate esters, such as methyl acrylate and methyl methacrylate as gypsum additives to improve the strength of the gypsum board. Although the polymers used improve the strength of gypsum boards, they do not provide resistance against water. Therefore, there is a continuing need for a water resistant gypsum board. It would also be useful if the Treatment that provides resistance to water does not weaken the gypsum board. I have found that this need can be met by treating the gypsum with a polymer containing as polymerized units a hydrophobic modified monomer. By hydrophobically modified monomer is meant an alkyl ester of methacrylic acid (with C 2 to C 40). The present invention provides a composition of from 80 to 99.5 parts by weight of calcium sulfate and from 0.5 to 20 parts by weight of a polymer including as polymerized units: a) from 1 to 100 parts by weight of at least one ester of methacrylic acid alkyl (with Ci2 to C o), b) from 0 to 99 parts by weight of at least one ethylenglycol unsaturated monomer, and e) 0 to 15 parts by weight of at least one monomer containing ethylene glycol unsaturated or salts thereof. In a second aspect, the present invention provides a method for protecting a gypsum board including: 1) mixing from 0.5 to 20 parts by weight of a polymer with 80 to 99.5 parts by weight of calcium sulphate enjagua; 2) molding the mixture to form a gypsum board; and 3) dry the gypsum board; wherein the polymer includes as polymerized units: a) from 1 to 100 parts by weight of at least one alkyl ester of methacrylic acid (with C12) a C0) b) from 1 to 100 parts by weight of at least one unsaturated ethylene glycol monomer, and e) from 0 to 15 parts by weight of at least one unsaturated ethylene glycol acid containing monomer or salts thereof. The polymer used in the present invention can be prepared by a single-step or multi-step process. The process for making the polymer can be the polymerization of solutions or the polymerization of emulsions using methyl-β-cyclodextrin ("CD"). See U.S. Patent Number 5,521,266 for a detailed description of the polymerization process of emulsions. The emulsion polymerization process using CD is preferred. The morphology of the polymer used in the present invention can be designed to optimize certain properties of the polymer. For example, the polymer can be manufactured with a core and shell morphology in which the nuclear polymer is designated in such a way that it has a transition temperature of low vitreous state than the polymer that creates the shell. Alternatively, the polymer constituting the core can be designated such that it has a glass transition temperature greater than the polymer constituting the shell. In this case, the core can act as a filler and the cortex can join the harder cores to help the formation of films. The polymers of Nucleus and bark can be prepared with "methods well known in the art." In the process used to prepare the samples within this application, a first step is prepared by adding an emulsion of monomer and sodium persulfate to a solution containing CD, deionized water and surfactant The first stage was reacted at 85 ° C. A second stage was prepared by making a second monomer emulsion and feeding it to a solution of sodium persulfate to the first stage already reacted. 85 ° C. The polymer used in the present invention contains as polymerized units from 1 to 100 parts by weight, more preferably from 40 to 95 by weight of at least one alkyl ester of methacrylic acid (with C 2 to C 40). ). It is further preferred that the polymer used in the present invention contain as polymerized units of from 60 to 95 by weight, preferably from 70 to 94 by weight, more preferably from 80 to 93 by weight of at least one alkyl acid ester. methacrylic (with C12 to C40) It is preferred that the alkyl ester of methacrylic acid is an alkyl ester of methacrylic acid (with Ci2 to C3Q) It is preferred that the alkyl ester of methacrylic acid be an alkyl ester of methacrylic acid. methacrylic acid (with Ci2 to Cj.8) The alkyl esters of methacrylic acid include, but are not limited to, lauryl methacrylate, cetyl methacrylate, stearyl methacrylate, behenyl methacrylate and eicosyl methacrylate. Beneficial properties can be obtained by using more than one alkyl ester of methacrylic acid (Ci 2 to C 40). The polymer used in the present invention may also contain as polymerized units from 0 to 99 by weight, preferably from 4 to 79 by weight, more preferably from 4 to 59 by weight of at least one ethylene glycol-unsaturated monomer. It is further preferred that the polymer used in the present invention contain co or polymerized units of from 4 to 39 by weight, preferably from 5 to 29 by weight, more preferably from 6 to 19 by weight of at least one unsaturated ethylene glycol monomer. Among the unsaturated ethylene glycol monomers for use in the preparation of the polymer compositions of the present invention, but are not limited thereto, the methacrylic ester msnomers, including methyl acrylate, ethyl acrylate, butyl acrylate, sodium acrylate, and ethylhexyl, decyl acrylate, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate and hydroxypropyl acrylate; acrylamide or substituted acrylamides; styrene or substituted styrene; vinyl acetate or other vinyl esters; vinyl monomers, such as vinyl chloride, vinylidene chloride, N-vinyl pyrrolidone; and acrylonitrile or methacrylonitrile.

Preferred are butyl acrylate, methyl methacrylate and styrene. The polymer used in the present invention may also contain as polymerized units from 0 to 15 by weight, preferably from 1 to 1, by weight, more preferably from 1 to 5 by weight of an msrimer containing an unsaturated ethylene glycol acid. or you get out of it. They stand out among the monomers containing ethylene glycol unsaturated acid, but are not limited to it ", acrylic acid, methacrylic acid, crotonic acid, phosphoethyl methacrylate, 2-acrylamido-2-methyl-l-propanesulfonic acid, sodium vinyl sulfonate , itacoic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate and maleic anhydride, acrylic acid and methacrylic acid are preferred, methacrylic acid is more preferred, the polymer used in the present invention it may also contain, as polymerized units, from 0 to 25 by weight, preferably from 0 to 15 by weight, more preferably from 0 to 10 by weight, of a monomers of unsaturated ethylene glycol fluorinated methacrylate, such as Zonyl ™ products (DuPont trademark) Chemical Company) The polymer used in the present invention may also contain as polymerized units from 0 to 80" by weight, preferably from 0 to 50 by weight, more preferably from 1 to 15 by weight of a monomer selected from alkyl styrene- (C6-C2o) and alkyl-alpha-methyl styrene, alkyl dialkyl itaconate (C6-) C2o), vinyl esters of carboxylic acids (C? O-C2o), N-alkyl acrylamide and methacrylamide of N-alkyl (Ca-C20), alkyl alpha-hydroxymethylacrylate (C? O ~ C2o), dialkyl diacrylate , 2 '- (oxidimethylene) (C8-C20), N-alkylacrylimide (C8-C2o) and alkyl vmylether (C? O-C2o). The polymer used in the present invention "may also contain as polymerized units from 0.1 to 10% by weight, preferably from 0.1 to 5% by weight, more preferably from 0.1% to 3% by weight, based on the weight of the polymer of a polymer element. cross-linking selected between a cross-linking agent and a cross-linking monomer By cross-linking agents is meant a compound having at least 2 reactive groups which will react with the acid groups found in the monomers of the cross-linking compositions. The present invention.- The crosslinking agents useful in the present invention include a polyaziridine, polyisocyanate, polycarbodiimide, polyamine and a polyvalent metal. The cross-linking agent is optional and can be added after the polymerization is complete. "~~ The cross-linked monomers are cross-linking elements that are incorporated with the monomers in the compositions of the present invention during the polymerization. Crosslinked monomers useful in the present invention include acetoacetate functional monomers, such as acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxyethyl methacrylate, allyl acetoacetate, acetoacetoxybutyl methacrylate, and 2-3-diacetoacetoxypropyl methacrylate; divinyl benzene, methacryloyl polyesters of polyhydroxy compounds, divinyl esters of polycarboxylic acids, diallyl esters of "polycarboxylic acids, dimethyl diallyl ammonium chloride, triallyl terephthalate, methylene bis-acrylamide, diallyl maleate, diallyl fumarate , hexamethylene bismaleamide, triallyl phosphate, trivinyl trimellitate, divinyl adipate, glyceryl trimethacrylate, diallyl succinate, divinyl ether, divinyl ethers of ethylene glycol or diethylene glycol diacrylate, glycol diacrylates or methacrylates of polyethylene, 1,6-hexanediol diacrylate, triacrylate or tetraacrylate of petaerythritol, glycol diacrylate of -neopentyl, allyl methacrylate, cyclopentadiene diacrylate, butylene glycol diacrylates or dimethacrylates, trimethylolpropane di- or triacrylates, methacrylamide, methylol methacrylamide, mixtures of these and similar. Methacrylamide, methacrylamide of n-methylol and mixtures thereof are preferred. The amount of cross-linking agent is chosen in such a way that the cross-linking element does not interfere with the formation of films. ~~ Chain transfer agents can be used to control the molecular weight of the polymer used in the present invention. Mercaptans, such as dodecyl mercaptan ("n-DDM"), stand out among the appropriate chain transfer agents. The agent of. Chain transfer can be used from 0.1% to 10% based on the total weight of the polymer composition. The composition of the present invention is typically prepared by mixing from 80 to 99.5 by weight of calcium sulfate, from 0.5 to 20 by weight, preferably from 1 to 15"" by weight, more preferably from 3 to 10 by weight of a polymer containing as polymerized units: a) from 1 to 100 by weight of at least one alkyl ester of methacrylic acid (with C12 to C40), b) from 0 to 99 by weight of at least one unsaturated ethylene glycol monomer, and e) 0 to 15 parts by weight of at least one monomer containing an unsaturated ethylene glycol acid or salts thereof and Water Add enough water to the composition so that the mixture can be stirred and poured. Typically, 30% to 50% water is used based on the weight of gypsum powder.

Preferably, 35% to 45% water based on "the weight of the gypsum is used." The composition may contain defoaming agents, such as dispersions of silicone compounds, typically, the defoaming agent is used from 0.1% to 1% by weight. Weight, based on the total weight of the composition It is preferred that the polymer used in the composition of the present invention contain as polymerized units: a) from 20 to 95 by weight of at least one alkyl ester of methacrylic acid (with C 2 to C 40), b) from 4 to 79 by weight of at least one unsaturated monoo-tolylene glycol, and e) from 1 to 10 parts by weight of at least one morphomer containing ethylene glycol unsaturated acid or salts In a more preferred embodiment, the polymer contains as polymerized units: a) from 40 to 95 by weight of at least one alkyl ester of methacrylic acid (with C? a C4Q), b) from 4 to 59 by weight of at least one ethylene glycol unsaturated monomer do, and c) from 1 to 5 by weight of at least one monomer which contains unsaturated ethylene glycol acid or salts thereof. The mixture is then molded and -shaped and "dried." Typically, the shape is a flat board. "" Drying can be achieved passively by exposure "to the air. Alternatively, the mixture can be heated to temperatures in the range of 50 ° C to 150 ° C to accelerate drying. The heat It can be radiant heat, forced hot air or a furnace. The process of the invention provides a method for protecting the gypsum board including: 1) mixing from 0.5 to 20 by weight, preferably from 1 to 15 by weight, more preferably from 3 to 10 by weight of a polymer with 80 to 99.5 by weight of calcium sulfate and water; molding the mixture to form a drywall; and 3) dry the gypsum board; wherein the polymer includes as polymerized units: a) from 1 to 100 by weight of at least one alkyl ester of methacrylic acid (with Ci2 to C40), b) from 0 to 99 by weight of at least one ethylene glycol monomer unsaturated, and c) from 0 to 5 by weight of at least one monomer containing unsaturated ethylene glycol acid or salts thereof. It is preferred that the polymer used in the process of the present invention contain as polymerized units: a) from 20 to 95 by weight of at least one alkyl ester of methacrylic acid (with Ci2 to C4o), b) of 4 to 79 by weight of at least one ethylenglycol monomer saturated, and e) 1 to 10 by weight-of at least one monomer containing unsaturated ethylene glycol acid or salts thereof. In a more preferred embodiment, the polymer contains as polymerized units: a) from 40 to 95 per "weight of at least one acid alkyl ester methacrylic (with C? 2 to C4Q), b) from 4 to 59 by weight of at least one unsaturated ethylene glycol monomer, e) from 1 to 5 by weight of at least one monomer-containing unsaturated ethylene glycol acid or salts The gypsum contains mainly calcium sulfate, which is commercially available.The gypsum board can be dried as described above.The polymer of the composition of the present invention and the process of the present invention can also be mixed with latex before Mix with the sulfate "of calcium and water. Any latex can be used. They stand out among the suitable latexes, but are not limited to "these, the butyl acrylate / methacrylate latex, methyl, butyl acrylate / styrene, styrene / butadiene and vinyl acetate." The amount of polymer mixed with the latex it is typically from 1 to 50 by weight, preferably from "5 to 45 by weight, more preferably from 10 to 40 by weight. The mixture is "typically combined with calcium sulfate and water as" described above. - Throughout the present patented application the following abbreviations are used: SMA = stearyl methacrylate MMA = methyl methacrylate MAA = methacrylic acid CD = methyl-β-cyclodextrin LMA = lauryl methacrylate _ _ The following examples are intended to demonstrate the compositions and method of the present invention and the benefits obtained in the gypsum board. The examples should not be construed as limiting the scope of the invention. The general procedure for preparing the polymers used in the present invention was as follows: for the stage, 400 g of deionized water, Triton® XN-45S anionic surfactant (Union Carbide Chemical Company trademark), and 28 were introduced. 6 ~ g of CD in a round-bottomed flask with a capacity of 4 liters with four necks, equipped with mechanical stirrer, temperature control device, condenser, monomer feed tubes and initiator, and nitrogen intake at room temperature. The contents were heated to 85 ° C while stirring under a nitrogen purge. A monomer emulsion was prepared separately. Solutions of 0.35% by weight of sodium carbonate (based on the total weight of the monomer in Ia and 2a stages) in 25 g of deionized water and 0.35% by weight of sodium persulfate were introduced into the reaction vessel. based on the total weight of the monomer in steps Ia and Ia) in 30 g of deionized water. The monomer emulsion was fed for a period of 20 minutes together with a 0.05% sodium persulfate initiator solution (based on the total monomer weight in steps Ia and 2a) in 210 g of deionized water.

For the 2nd step, a second monomer emulsion was prepared using 625 g of deionized water, 7.8 g of Triton® XN-45S anionic surfactant and monomers. Immediately after the end of the monomer emulsion feed of the stage Ia, the monomer emulsion of the 2nd stage was fed for a period of 3 hours together with the sodium persulfate initiator solution. The monomers of the monomer emulsions Ia and 2 a were selected such that the polymers of Table 1 were obtained (based on the weight percentage of the monomer). The list of the different polymers includes polymers with and without n-DDM. The use of n-DDM decreases the molecular weight of the polymer (from about 500,000 to about 150,000) contains 0.5% by weight, based on the weight of the powder plaster Lipocol L-23 (commercially available through Lipo Chemical Inc.) _ Zonyl is a trademark of DuPont Chemical Company Preparation of gypsum board in the laboratory An aliquot of polymer 1 (4.95 grams) was measured in a container of plastic and diluted with 33.94 grams of water. The diluted solution (approximately 4% solid) was mixed with 1.1 grams of 10% solid dispersant, Tamo®-L (sodium salt of naphthalene-formaldehyde condensate from Rohm and Hass Company). The solution was gradually mixed in 50 grams of dry gypsum powder. The mixture was vigorously mixed by hand to form a paste with a spatula. Within 3 minutes, the gypsum paste was poured into a polypropylene mold (2.54 cm x 2.54 cm x 2.54 cm) to solidify. The cubes of the solidified sample were dried at room temperature or in an oven at 160 ° C for 18 minutes. The samples were dried and ready for testing. The above procedure was repeated with different amounts of polymer added, so that samples were prepared with a polymer addition of 3%, 5% and 10% based on the total weight of the sample. A control sample was also prepared (no polymer was added) as described above.

Soak test in water The sample cubes were immersed in a water bath at a constant temperature of 2L ° C with a water margin of 2.54 cm over the top of the samples. The weight of the samples was measured in intervals of one minute up to 2 hours. The results of the test are shown in Table 2. Table 2 Polymer 1. Absorption of water (%) Time Control Addition Addition of Addition of (min.) 3% 10% 0 42 49 10 48 Polymer 2 Absorption of water (%) Control Time Addition Addition Addition of (min.) 3% 5% 10% 30 49 13 60 47 20 10 120 47 20 13 The above data indicates that the gypsum board prepared in accordance with the present invention has excellent resistance to Water. _ _ Water dispersion test Gypsum board samples were prepared as described above. A drop of water (approximately 0.04 grams) was poured through a plastic pipette on the surface of the sample and then the time it took the drop to disappear from the surface was measured in seconds and minutes. The longer the time, the better the water repellency of the samples. The results of this campaign are shown in Table 3 The above data further demonstrate that the gypsum board prepared in accordance with this invention has excellent resistance to water. Compressive strength The previous cubic samples were crushed with a Tinus Olsen Tester with cross gauge speed of 0.26 cm per minute and digital reading of the compressive strength of pounds per square inch, which were converted to ne tons per square meter ( N / m2). The results are shown in Table 4. __ _ The above data indicates that the polymers used in the present invention do not weaken the gypsum board.

Claims

1. A composition comprising: from 80 to 99.5 parts by weight of calcium sulfate; and from 0.5 to 20 parts by weight of a polymer including as polymerized units: a) from 1 to 100 parts by weight of at least one alkyl ester of methacrylic acid with (C12 to C40), b) from 0 to 99 parts by weight "of at least" an unsaturated ethylene glycol monomer, and e) from 0 to 15 parts by weight of at least one monomer containing unsaturated ethylene glycol acid or salts thereof, ~ U - -

2. The composition in accordance with Claim 1 wherein the polymer is present from 1 to 15-by weight and comprises as polymerized units: a) from 20 to 95 by weight of at least one alkyl ester of methacrylic acid (with Ci2 to C4o), b ) from 4 to 79 by "weight of at least one unsaturated ethylene glycol monomer, and e) from 1 to 10 parts by weight of at least one monomer containing unsaturated ethylene glycol acid or salts thereof.

3. The composition in accordance with Claim 1 wherein the polymer is present from 3 to 10 by weight and comprises as a polymerized properties: a) from 40 to 95 by weight of at least one alkyl ester of methacrylic acid (with C? 2 to C4o), b) from 4 to 59 by weight of less an unsaturated ethylene glycol monomer, and e) from 1 to 10 parts by weight of at least one monomer-containing unsaturated ethylene glycol acid or salts thereof.

4. A method for protecting gypsum board comprising: 1) mixing 0.5 to 20 parts by weight of a polymer with 80 to 99.5 parts by weight of calcium sulfate in water; 2) molding the mixture to form a gypsum board; Y 3) dry the gypsum board; wherein the polymer includes as polymerized units: a) from 1 to 100 parts by weight of at least one alkyl ester of methacrylic acid (with 1Z to C0), b) from 1 to 100 parts by weight of at least one monomer "unsaturated ethylene glycol, ee) from 0 to 15 parts by weight of at least one unsaturated ethylene glycol acid containing monomer or salts thereof

5. The method according to claim 4 wherein the polymer is present from 1 to 15 by weight and comprises as polymerized units: a) from 20 to 95 by weight of at least one alkyl ester of methacrylic acid (with Ci2 to C40), b) from 4 to 79 by weight of at least one ethylene glycol monomer unsaturated, and e) from 1 to 10 parts by weight of at least one monomer containing unsaturated ethylene glycol acid or salts thereof.

6. The method of compliance with the Claim 4 wherein the polymer is present from 3 to 10 by weight and comprises as polymerized units: a) from 40 to 95 by weight of at least one alkyl ester of methacrylic acid (with C 2 to C 4), b ) from 4 to 59 by "weight of at least one unsaturated ethylene glycol monomer, ye) of from 1 to 10 parts by weight of at least one monomer containing unsaturated ethylene glycol acid or salts thereof.