High acid styrene acrylic acid and acrylic emulsion copolymer modified urea formaldehyde binder for mineral fibers

Abstract

The invention provides modified urea formaldehyde (UF) resin adhesive compositions and mineral fiber mats having emulsion polymer modifiers that include 5 wt.% to 25 wt.% of a copolymerized carboxylic acid functional monomer in a copolymerized form. These emulsion polymers have a measured glass transition temperature (DSC) in the range of -40°C to 70°C and a large average particle size. Further, these emulsion polymers include less than 30% of the copolymerized acid in a neutralized form and do not excessively thicken aqueous compositions containing these emulsion polymers. These modified UF resin adhesive compositions achieve good dilution stability in use and high tensile strength in products containing these modified UF resin adhesive compositions.

Description

Technical Field

[0001] This invention relates to aqueous adhesive compositions comprising high-acid acrylic or styrene-acrylic emulsion polymer modified urea-formaldehyde resin (UF resin) and methods for using these compositions to manufacture fiber or glass fiber mat products. Background Technology

[0002] Fiberglass mats, and those made from synthetic fibers and fiber blends, are widely used in the building materials industry, for example as insulation, as a substrate for composite flooring, or as a substrate for roofing shingles. Fiber mats, and especially fiberglass mats, are typically manufactured commercially via a wet-laid process, which is carried out on what can be considered an improved papermaking apparatus. In this process, fiber slurry deposited on a moving screen or cylinder is processed into sheet-like fiber mats by removing water (usually by suction and / or vacuum devices). A resin or polymer binder is then applied to the thus formed fiber mat to hold it together. After the binder is applied, the mat is solidified or cured by heating to provide the desired mat integrity.

[0003] Adhesive formulations widely used in the manufacture of fiber mats, particularly glass fiber mats, include thermosetting urea-formaldehyde (UF) resins. UF resins are commonly used because they are relatively inexpensive. However, manufacturing glass fiber mats with adhesives that are essentially composed of UF resins often results in brittle mats. Furthermore, especially when the glass fiber mats are subjected to stress during manufacturing, strength needs to be developed in the early curing time to avoid process delays and downtime caused by breakage in the continuous mat line. Therefore, UF resin adhesive compositions may also include polymeric adhesives comprising emulsion polymers or solution polymers, which impart mat strength properties to the ultimately cured mat and can improve mat strength early in the curing process, during the transport of the mat from its initial formation to and through the curing oven.

[0004] U.S. Patent No. 6,642,299B2 to Wertz et al. discloses a urea-formaldehyde resin adhesive containing an additive comprising a solution of a styrene-maleic anhydride copolymer as a water-soluble UF modifier. This solution comprises a physical blend of the styrene-maleic anhydride copolymer with a small amount of an undisclosed styrene-acrylic acid or styrene-acrylate emulsion copolymer. The additive contains at most 10 wt.% adhesive solids and does not contain any acidic emulsion copolymer. To prevent gelation of the adhesive due to the reaction of the acid in the additive with the UF resin, the pH of the Wertz composition must be maintained in the preferred range of 7 to 8.5, and the amount of the additive polymer and the acid content of the entire Wertz adhesive composition must be kept very low.

[0005] The inventors are dedicated to solving the problem of providing waterborne polymer-modified UF resin adhesive compositions for use in, for example, bitumen-coated roofing shingles, which have good storage stability while enabling the fiber mat to have improved tensile strength and flexibility. Summary of the Invention

[0006] According to the present invention, the aqueous modified urea-formaldehyde resin (UF resin) adhesive composition comprises UF resin and, based on the total solids of the UF resin adhesive composition, 2.5 wt.% to less than 15 wt.%, or preferably 5 wt.% to 12.5 wt.%, as a modifier of at least one emulsion polymer, the emulsion polymer having a pH of 4 to 7.5, or preferably 4 to less than 7.0, or more preferably 4 to 6.5, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of (meth)acrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) based on the total weight of all monomers used to form the emulsion copolymer, in an amount of 5 wt.% to 25 wt.%, or preferably 10 wt.% to 20 wt.%, of one or more monomers containing olefinically unsaturated carboxylic acid groups, preferably acrylic acid or methacrylic acid, and further wherein the emulsion polymer has a measured glass transition temperature (DSC) in the range of -40°C to 70°C, or preferably -30°C to 60°C. Preferably, the vinyl aromatic monomer is selected from styrene or α-methylstyrene.

[0007] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may comprise an emulsion copolymer, wherein, in copolymer form, (i) one or more alkyl esters of the (meth)acrylic acid are selected from: a) butyl acrylate, ethyl acrylate, methyl acrylate, ethylhexyl methacrylate and at least one C1 to C1 group of (meth)acrylic acid other than butyl acrylate, ethyl acrylate, methyl acrylate or ethylhexyl methacrylate. 18 A mixture of alkyl esters; b) a mixture of any one of butyl acrylate, ethyl acrylate, methyl acrylate or ethylhexyl methacrylate with methyl methacrylate; or c) the mixture having one or more vinyl aromatic monomers (a) or b).

[0008] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may include, in copolymer form, one or more polyene-bonded unsaturated crosslinking monomers, such as allyl methacrylate emulsion polymers, at 0 wt.% to 2 wt.% based on the total weight of all monomers used to form the emulsion copolymer.

[0009] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may have a weight-average molecular weight of 100,000 to 2,000,000, or preferably 300,000 to 1,500,000, or preferably 400,000 to 1,000,000.

[0010] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may have a weight-average particle size of 100 nm to 500 nm, or preferably 170 nm to 400 nm.

[0011] The modified urea-formaldehyde resin adhesive compositions according to the present invention may be substantially free of emulsion polymers containing phosphorus- and / or sulfuric acid-containing monomers in copolymer form. However, the compositions of the present invention may contain phosphorus- and / or sulfur-containing molecular weight modifiers, such as sodium hypophosphite and n-dodecyl mercaptan.

[0012] The modified urea-formaldehyde resin adhesive composition according to the invention comprises 2 wt.% or less, or preferably 1 wt.% or less, of a solution polymer, each wt.% based on the total solids in the modified UF resin adhesive composition, or more preferably, may be substantially free of solution polymer, which in copolymer form comprises, based on the total weight of all monomers used to form the emulsion copolymer, more than 50 wt.% of monomers containing olefinically unsaturated carboxylic acid groups.

[0013] The modified urea-formaldehyde resin adhesive composition according to the invention may contain 5 wt.% or less, or preferably 0.5 wt.% or less, or more preferably 0.1 wt.% or less, of phenolic resin based on the total adhesive composition solids.

[0014] According to another aspect of the invention, a mineral fiber mat (such as preferably roofing shingles) comprises a web of mineral fibers, preferably glass fibers, and a total solids composition based on the mineral fibers plus a modified urea-formaldehyde resin (UF resin) binder composition, in an amount of 5 wt.% to 30 wt.% of the modified UF resin binder composition, which comprises 85 wt.% to 97.5 wt.% of urea-formaldehyde resin and 2.5 wt.% to less than 15 wt.%, or preferably 5 wt.% to 12.5 wt.% as a modifier of at least one emulsion polymer, all the weights of the binder composition being based on the total binder solids weight, wherein the emulsion polymer has a content of 4 to 7.5. Or preferably, a pH of 4.0 to less than 7.0, and comprising, in copolymer form, (i) one or more alkyl esters of (meth)acrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) one or more monomers containing olefinically unsaturated carboxylic acid groups, preferably acrylic acid or methacrylic acid, in an amount of 5 wt.% to 25 wt.%, or preferably 10 wt.% to 20 wt.%, based on the total weight of all monomers used to form the emulsion copolymer, and further wherein the emulsion polymer has a measured glass transition temperature (DSC) in the range of -40°C to 70°C, or preferably -35°C to 60°C. Preferably, the vinyl aromatic monomer is selected from styrene or α-methylstyrene.

[0015] The modified UF resin adhesive composition in the mineral fiber mat according to the present invention may include any of the adhesive compositions disclosed above in the "Summary of the Invention", including all disclosed preferences.

[0016] In another aspect, the present invention provides a method comprising: forming a modified UF resin adhesive composition from a urea-formaldehyde resin (UF resin) and the following:

[0017] Based on the total solids of the UF resin adhesive composition, 2.5 wt.% to less than 15 wt.%, or preferably 5 wt.% to 12.5 wt.%, of at least one emulsion polymer as a modifier; and applying the composition to a wet-laid continuous glass fiber mat and heating to cure the composition, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of (meth)acrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) based on the total weight of all monomers used to form the emulsion copolymer, an amount of 5 wt.% to 25 wt.%, or preferably 10 wt.% to 20 wt.%, of one or more monomers containing olefinically unsaturated carboxylic acid groups, preferably acrylic acid or methacrylic acid, and further wherein the emulsion polymer has a measured glass transition temperature (DSC) in the range of -40°C to 70°C, or preferably -35°C to 60°C. In the method according to the invention, the emulsion polymer modifier may have a pH of 4 to 7.5, or preferably 4 to 7. Preferably, the vinyl aromatic monomer in the emulsion polymer is selected from styrene or α-methylstyrene. The method according to the invention is particularly useful for preparing glass mat adhesives for roofing shingles (such as bitumen-coated roofing shingles). Detailed Implementation

[0018] According to the method of the present invention, the modified urea-formaldehyde (UF) resin adhesive composition comprises a high-acid-content emulsion polymer that provides an adhesive with good storage and dilution stability. Additionally, the modified UF resin adhesive composition enables the provision of mineral fiber mats with good flexibility and tensile strength properties. The modified UF resin adhesive composition enables the provision of mineral fiber mats or glass mats, such as roofing shingles, for example, bitumen-coated roofing shingles with enhanced durability. Simultaneously, because the modified UF resin adhesive composition comprises an emulsion polymer and is substantially free of solution polymers, the adhesive composition maintains a reasonable viscosity level under application conditions throughout its formulation and application to the mineral fiber mat, ensuring that the wet mesh surface is adequately treated with the adhesive. The emulsion polymer modifier of the present invention allows the aqueous UF resin adhesive composition to flow to all parts of the mat, while enabling the UF resin to develop early curing strength, thereby limiting the risk of breakage of the continuous mineral fiber mat substrate. Complete treatment or coverage of the glass mat surface area is crucial. If the entire mineral fiber mat wet mesh is not uniformly treated with the adhesive, the likelihood of glass mat breakage increases significantly. Emulsion polymer modifiers are essentially formaldehyde-free.

[0019] Unless otherwise indicated, all temperature and pressure units are room temperature (21°C to 23°C) and standard pressure (1 atm). Additionally, unless otherwise stated, all conditions include a relative humidity (RH) of 40%.

[0020] Unless the context clearly indicates otherwise, the singular forms “a”, “an”, and “the” include plural indicators.

[0021] Unless otherwise indicated, the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0022] All ranges are inclusive and combinable. Thus, for example, the disclosure of a composition containing 5 wt.% or less, or preferably 0.5 wt.% or less, or more preferably 0.1 wt.% or less of phenolic resin will be interpreted as including the ranges of 0 wt.% to 5 wt.%, 0 wt.% to 0.1 wt.%, 0 wt.% to 0.5 wt.%, 0.1 wt.% to 5 wt.%, and 0.5 wt.% to 5 wt.%.

[0023] All phrases containing parentheses indicate either or both of the substances enclosed in the parentheses and their absence. For example, in an alternative, a phrase including "(meth)acrylate" includes both acrylates and methacrylates.

[0024] As used herein, the term "aqueous" or "aqueous solvent" includes water and mixtures that are essentially composed of water and water-miscible solvents.

[0025] Unless otherwise specified, as used herein, the terms “average particle size” or “PS” refer to the weight-average particle size as determined using a Brookhaven BI-90 instrument (Brookhaven Instruments Corporation, Austin, TX).

[0026] Unless otherwise specified, as used herein, the phrase “adhesive application conditions” refers to ambient or room temperature (21 to 23°C) and standard pressure.

[0027] As used herein, the phrase “based on the total weight of monomers used to form the emulsion polymer” refers to all addition monomers, such as carboxylic acid-functional vinyl or olefinically unsaturated monomers, and chain transfer agents that leave residues in the polymer, such as hypophosphite or their salts.

[0028] Unless otherwise stated, as used herein, the terms "molecular weight" or "Mw" refer to the molecular weight of a substance as defined in aqueous gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent at 40 °C on three columns at different resolutions, such as PLgel columns (Polymer Labs), 100 Å, and 10 Å. 3 Angstrom, 10 4 The weight-average molecular weight was determined at an injection volume of 1 mil / min and 30 cm length, 7.8 mm inner diameter (ID), and 100 μL. This weight-average molecular weight was measured using a polymer laboratory such as CALIBRE. TM The software is calibrated relative to narrow polystyrene standards. The system is calibrated using polystyrene standards. As used herein, Mw is measured in grams per mole (g / mol).

[0029] As used herein, the term “substantially free of” any material or ingredient, such as formaldehyde, volatile amines, sulfur-containing monomers, or solution polymers, means any composition, article comprising them, or method of preparation or use thereof, wherein the composition, article, or method mentioned herein does not contain such added material or ingredient.

[0030] As used herein, the terms "measured glass transition temperature" or "measured Tg" refer to the glass transition temperature of the emulsion polymer as determined by differential scanning calorimetry (DSC) according to the following examples. Tg 10 mg of sample was dried overnight at 60 °C in an aluminum DSC sample pan. The sample pan was then transferred to a DSC instrument (TA Instruments Q2000), where the sample was heated to 120 °C and rapidly cooled to -100 °C. Data were collected while the temperature was increased from -50 °C to 200 °C at a rate of 10 °C / min. The midpoint of the inflection point of the data curve was reported.

[0031] As used herein, the phrase “total solids” or “total binder solids” or its equivalents refer to the weight of any given component relative to the total weight of all non-volatile components in the binder or reference composition. Volatile components include water and ammonia, as well as volatile solvents that evaporate at standard pressure and at 40°C or lower.

[0032] As used herein, the term “conditions of use” refers to standard pressure and a temperature range from ambient temperature to the upper limit of the published adhesive curing temperature.

[0033] As used in this article, the term "wt.%" means weight percentage.

[0034] The modified UF resin adhesive composition and mineral fiber mat according to the present invention comprise an emulsion copolymer modifier having a large percentage of copolycarboxylic acid functional monomers. The emulsion polymer comprises 5 wt.% to 25 wt.% monomers containing olefinically unsaturated carboxylic acid groups based on the total weight of all monomers used to form the emulsion copolymer. In contrast to conventional polymers made from monomers containing olefinically unsaturated carboxylic acid groups, such as solution polymers or alkali-sold emulsions (ASE), the emulsion polymer of the present invention is not water-soluble and does not swell in alkali. In fact, the pH of the emulsion polymer is maintained below neutral, such as between pH 4 and 7.5, or 4 to 7, which maintains the low viscosity of the modified UF resin adhesive composition and prevents the emulsion polymer from reacting with the urea-formaldehyde resin until the desired time, such as during curing. Therefore, the emulsion polymer does not contain amounts of ammonia or another neutralizing agent that would raise the pH above the desired range. The emulsion polymer of the present invention contains less than 30%, or preferably less than 25%, or more preferably less than 15% of carboxylic acid groups in a neutralized form. Therefore, if the polymer has 15 wt.% carboxylic acid groups based on the total weight of the monomers used to prepare the polymer in copolymer form, then 4.5% or less of the polymer contains neutralized acid (carboxylic acid ester) groups based on the total weight of the monomers used to prepare the polymer.

[0035] A suitable modified UF resin adhesive composition comprises a UF resin and, based on the total solids of the UF resin, 2.5 wt.% to less than 15 wt.%, or preferably 5 wt.% to 12.5 wt.%, as a modifier at least one emulsion polymer having a pH of 4 to 7, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of (meth)acrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) based on the total weight of all monomers used to form the emulsion copolymer, in an amount of 5 wt.% to 25 wt.%, or preferably 10 wt.% to 20 wt.%, of one or more monomers containing olefinically unsaturated carboxylic acid groups, and further wherein the emulsion polymer has a measured glass transition temperature (DSC) in the range of -50°C to +70°C, or preferably -30°C to +60°C. Preferably, if used, the vinyl aromatic monomer is selected from styrene or α-methylstyrene.

[0036] Suitable alkyl esters of (i) (meth)acrylic acid that can be used to prepare the emulsion polymers of the present invention may include, for example, butyl acrylate, ethyl acrylate, methyl acrylate, ethylhexyl methacrylate, or (meth)acrylic acid of C1 to C1-C2 other than butyl acrylate, ethyl acrylate, methyl acrylate, or ethylhexyl methacrylate. 18Alkyl esters, such as methyl methacrylate, ethyl methacrylate, hexyl (meth)acrylate, or fatty (meth)acrylates, such as lauryl methacrylate. Suitable (i) vinyl aromatic monomers that can be used to prepare the emulsion polymers of the present invention may include, for example, styrene, α-methylstyrene, vinyltoluene, or C2 to C8 alkylstyrene.

[0037] Suitable (ii) "monomers containing olefinically unsaturated carboxylic acid groups" that can be used to prepare the polymers of the present invention may include, for example, methacrylic acid, acrylic acid, itaconic acid and maleic acid or their anhydrides, preferably acrylic acid and methacrylic acid.

[0038] (ii) The upper limit for monomers containing olefinically unsaturated carboxylic acid groups indicates the amount of emulsion polymers with acceptable viscosity and acceptable low coagulation levels that are allowed to be produced at a practical solids level of 40 wt.% or higher.

[0039] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may include, in copolymer form, one or more polyene-bonded unsaturated crosslinking monomers, such as allyl methacrylate emulsion polymers, at 0 wt.% to 2 wt.% based on the total weight of all monomers used to form the emulsion copolymer.

[0040] In weather-resistant mineral fiber mat applications, such as for roof shingles, the preferred total amount of (i) vinyl aromatic monomers used to prepare the emulsion polymers of the present invention comprises, based on the total weight of all monomers used to form the emulsion copolymer, 15 wt.% or less, or more preferably 11 wt.% or less.

[0041] Preferably, in order to enhance the flexibility of the mineral fiber pads prepared therefrom, the emulsion polymer according to the invention specifically does not contain monomers including N-hydroxymethyl groups, such as N-hydroxymethylacrylamide or N-hydroxymethylmethacrylamide, or glycidyl functional monomers, in copolymer form.

[0042] The emulsion polymer modifiers of the present invention include aqueous emulsion polymers, such as those formed in the presence of an emulsifier or surfactant. These emulsion polymers can be prepared by conventional aqueous emulsion polymerization methods, such as in the presence of an initiator such as a peroxide (e.g., dibutyl peroxide), a peracid (e.g., persulfate), or sulfinic acid or a salt thereof. Emulsion polymerization may include one or more chain transfer agents, such as thiols.

[0043] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may have a molecular weight of 100,000 to 2,000,000, or 300,000 to 1,500,000 or higher, or preferably 400,000 to 1,000,000.

[0044] The emulsion polymer in the modified urea-formaldehyde resin adhesive composition according to the present invention may have a weight-average particle size of 100 nm to 500 nm, or preferably 170 nm to 400 nm.

[0045] The emulsion polymer in the modified UF resin adhesive composition of the present invention may have a solid content of 40 wt.% to 60 wt.%.

[0046] Suitable urea-formaldehyde (UF) resins used according to the present invention are known and widely available commercially. These resins are formed, for example, by reacting urea and formaldehyde to form a compound containing hydroxymethyl groups, followed by further reaction under heat, condensation, or curing with or without a catalyst to form a polymer. The hydroxymethyl groups in UF resins are known to react with active hydrogen groups, such as other hydroxymethyl groups, to form ethers or methylene groups, thereby forming a polymer structure. Such polymer structures are generally brittle, and nonwovens containing them as adhesives tend to be relatively rigid. Examples of commercially available urea-formaldehyde resins include Casco-Resin FG-413F resin (Borden, Inc.) and GP... TM 2980RESI-MAT TM Glass pad adhesive resin (Georgia-Pacific).

[0047] The modified urea-formaldehyde resin adhesive composition according to the present invention can be substantially free of emulsion polymers containing phosphorus- and / or sulfuric acid-containing monomers in copolymer form.

[0048] The modified urea-formaldehyde resin adhesive composition according to the invention comprises 2 wt.% or less, or preferably 1 wt.% or less, of a solution polymer, each wt.% based on the total solids in the modified UF resin adhesive composition, or more preferably, may be substantially free of solution polymer, which in copolymer form comprises, based on the total weight of all monomers used to form the emulsion copolymer, more than 50 wt.% of monomers containing olefinically unsaturated carboxylic acid groups.

[0049] The modified UF resin adhesive composition of the present invention may contain, based on the total solids of the adhesive composition, 0.01 wt.% to 2 wt.% of each of the additives, including surfactants or dispersants for adjusting surface tension, silane coupling agents, dust removal oils, and white water flocculants such as polyacrylamide.

[0050] As measured on a DV-III Ultra LV Brookfield viscometer, the modified UF resin adhesive composition of the present invention should have a viscosity of 5 centipoise (cP) to 60 cP, or preferably 40 cP or less, or more preferably 30 cP or less, at 25°C, 15 wt.% solids (diluted with water), and 30 rpm shear.

[0051] In another aspect, the present invention provides methods comprising forming a modified UF resin adhesive composition from urea-formaldehyde resin (UF resin), applying the composition to a wet-laid continuous glass fiber mat, and heating to cure the composition. The aqueous adhesive composition prepared according to the present invention is particularly useful as a glass mat adhesive for roofing shingles (such as bitumen-coated roofing shingles). The formation method comprises mixing an emulsion polymer, any additives, and the UF resin, and then diluting the resulting composition prior to application.

[0052] To form the adhesive composition of the present invention, the emulsion polymer can be added to the UF resin before, during, or shortly before use, or the emulsion polymer and any additives can be supplied in the form of an additive blend, which is then added to the UF resin and diluted with water to form the modified UF resin adhesive composition. The modified UF resin adhesive composition can be formed in shear presence and at a temperature of up to 70°C, either up to 3 days before application or immediately before application. The modified UF resin adhesive composition according to the present invention exhibits excellent dilution stability.

[0053] Methods of using the modified UF resin adhesive composition of the present invention include treating a wet-laid fiberglass mat with the adhesive composition by immersing the mat in an excess of the adhesive composition, or by directly coating or impregnating the fiber mat with the adhesive, for example, using a falling film curtain coater, and then curing the adhesive. Curing includes heat-treating the adhesive-treated mat at 100°C to 400°C, or preferably 180°C to 260°C.

[0054] Preferably, the processing in the method of the present invention includes immersing the fiberglass mat in an excess of adhesive composition, or, for example, directly coating or impregnating the fiber mat with adhesive using a falling film curtain coater.

[0055] In addition to manufacturing roofing shingles, the treated glass pads of the present invention can also be used as a substrate for manufacturing composite flooring, as a substrate for manufacturing wall panels (instead of similar sheets traditionally made of wood, cellulose or asbestos fibers), as a substrate for printed circuit boards or battery separators, as a filter material, as a strip, as a reinforcing sparse cloth in cement and non-cement coatings for masonry buildings, and as a finishing material for laminated products such as foam composites and gypsum boards.

[0056] The following examples illustrate the invention. Unless otherwise stated, all parts and percentages are by weight, and all temperatures are in °C.

[0057] Example

[0058] In the examples and Tables 1, 2 and 3 below, the following abbreviations are used: AA: acrylic acid, AN: acrylonitrile; BA: butyl acrylate, DVB: divinylbenzene; IA: itaconic acid, MAA: methacrylic acid, MMA: methyl methacrylate, nMOA: n-hydroxymethylmethacrylamide, S: styrene, SHP: sodium hypophosphite, SSS: sodium styrene sulfonate; RT: room temperature.

[0059] The following test methods are used in the following embodiments.

[0060] Tensile strength The dry tensile strength of the water-based curable compositions in Table 1 was evaluated on glass microfiber filter sheets (20.3 cm × 25.4 cm, catalog number 1820-866, Whatman International Ltd., Maidstone, England). Each sheet was impregnated with each adhesive composition, placed between two cardboard sheets of similar size, and run through a roller impregnation machine at a roller pressure of 68.9 kPa (10 psi). The coated sheets were then dried by heating in a Mathis oven at 90°C for 1.5 minutes. The weight after drying was determined to calculate the amount of adhesive added (15 wt% + / - 2 wt% adhesive added). The dried sheets were then cured in a Mathis oven at 190°C for 60 seconds and 180 seconds, as indicated. The cured sheet was cut into strips measuring 2.54 cm (1 in) × 10.16 cm (4 in), and the longitudinal tensile strength was tested using a Thwing Albert tensile Tester (Thwing Albert Instrument Company, West Berlin, NJ) equipped with a 1 kN load sensor. The clamp gap was 2.54 cm (1 in), and the crosshead speed was 2.54 cm / min (1 inch / min). The strips were tested “as is” at room temperature. Room temperature tensile strength, RT-TSAlternatively, the test can be performed immediately after immersion in water maintained at 80°C for 30 minutes. Tensile strength is recorded as the peak force measured during separation. The reported data are the average of values ​​recorded from 20 to 30 treated and cured strips of each filter sheet for each adhesive composition tested. Acceptable room temperature tensile strength after complete curing at 180 seconds is those greater than 20 N, or preferably greater than 25 N. The results are presented in Table 2 below.

[0061] Dilution stability The stability of the indicated adhesive compositions was tested by diluting them in 20 ml vials with water and mixing or shaking on a shaker, followed by visual observation at indicated intervals or times. Unstable mixtures were defined as those that produced sediment / film, gel, or phase separation. The process from phase separation to the formation of sediment / film that could not be redispersed was considered progressively unstable. In particularly unstable mixtures, sediment / film persisted even with stirring. For the 2:1 test, 1.0 ml of each undiluted aqueous adhesive composition was mixed in a test tube with 2.0 ml of water containing a mixture of 0.06 wt.% (as solids) of polyacrylamide thickener and alkylamine dispersant, and stability was tested after the indicated time and temperature. For the 5:1 test, 1.0 ml of each aqueous adhesive composition was mixed in a test tube with 5.0 ml of water, and stability was tested after 24 hours at room temperature and at any other indicated time and temperature. The results are presented in Table 3 below.

[0062] The stability rating system and related abbreviations for the data reported in Table 3 below are as follows: Homogeneity, or the first letter, refers to whether the adhesive mixture is in a single liquid phase (homogeneous) or separated into two liquid phases (typically existing as two layers). Ratings are H (homogeneous), S (separated), or TS (completely separated). Sedimentation, or the second letter, refers to the accumulation and degree of sedimentation in the adhesive mixture rating: NS (no sedimentation or film at the top of the sample); F (film formation at the liquid surface); S (sedimentation present). Redispersibility, or the third letter in the series, tests how the sedimentation / or film responds when the test tube is inverted. Ratings are D (sedimentation / film dispersed, making the bottom of the test tube clear); DND (sedimentation / film not dispersed and still present even when the test tube is inverted). The term "vortex" is used to describe a situation where the mixture does not have a clearly defined multilayered liquid or solid phase, but still has some slight levels of clear liquid / clear liquid phase incompatibility. Unstable mixtures are defined as those that produce sedimentation, gelation, or phase separation. The results are considered to be gradually unstable due to phase separation and sediment / film formation. Particularly unstable mixtures are those in which sediment / film persists even under stirring (inverted test tube).

[0063] Synthesis Example A: Emulsion Polymer Synthesis296.2 g of deionized water and 0.025 g of inhibitor were added to a 5 L round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and then heated to 88 °C. A monomer emulsion was prepared from 230.7 g of deionized water, 41.1 g of a 30% aqueous solution of sodium lauryl ether sulfate surfactant diluted with 30 g of deionized water, 700.8 g of BA, and 123.7 g of AA. At 88 °C, a solution of 12.4 g of SHP dissolved in 18.9 g of deionized water was added to the reaction flask, followed by a mixture of 2.84 g of sodium hydroxide dissolved in 10 g of deionized water. A 30% aqueous solution of 13.1 g of sodium lauryl ether sulfate surfactant was diluted with 10 g of deionized water.

[0064] A 45.7 g aliquot of the monomer emulsion was added to a flask, followed by the addition of 3.39 g of ammonium persulfate dissolved in 15.30 g of deionized water. After waiting for the peak exothermic reaction (5–10 min), the remaining monomer emulsion and a separate solution of 3.43 g of ammonium persulfate dissolved in 72.3 g of deionized water were gradually added over 130 min while maintaining the temperature at 86 °C. The feed rate was 50% for the first 20 min, and then 100% thereafter. After this addition was complete, the reaction mixture was maintained at 86 °C for 10 min. After this maintenance, 39.4 g of sodium hydroxide dissolved in 199.2 g of deionized water was gradually added over 20 min, followed by a maintenance of 10 min. After holding at approximately 75°C, a solution of 3.64 g of aqueous tert-butyl peroxide (70 wt.%) diluted in 14.3 g of deionized water and a separate solution of 2.5 g of sodium bisulfite dissolved in 28.9 g of deionized water were gradually added to the reaction mixture over 30 minutes, followed by holding for 15 minutes. After this holding, the reaction mixture was cooled to room temperature. The resulting emulsion polymer product was filtered through a 100-mesh sieve and a 325-mesh sieve, where only trace amounts of condensate were collected.

[0065] The emulsion polymer obtained in Example 7 has a content of 45.3%, as measured by drying approximately 0.5 g of sample in a 150°C forced-air oven for 30 minutes. Solid content And a pH of 4.8. As measured using a Brookhaven BI-90 instrument, the emulsion polymer particles... Average particle size It is 188nm. Emulsion polymers TgDetermined by differential scanning calorimetry (DSC): Approximately 10 mg of sample was dried overnight at 60°C in an aluminum DSC sample pan. The sample pan was then transferred to the DSC instrument (TA Instruments Q2000), where the sample was heated to 120°C, rapidly cooled to -100°C, and data were collected while the temperature was increased from -50°C to 150°C at a rate of 10°C / min. The measured Tg of the emulsion polymer was -34°C.

[0066] Three samples of each different monomer composition were prepared using the above-described synthetic procedure. Examples 8, 9, 10, 11, and 12 in Table 1 followed the above-described synthetic procedure. Except for the monomer emulsion, which was varied according to the emulsion polymer composition, all the emulsion polymers shown in Table 1 below were formed in the manner described in Synthetic Example A.

[0067] In the following examples, urea-formaldehyde (UF) supplied at 65.5% by weight solids was reacted with the following polymer aqueous solution using a Caframo stirring vessel equipped with a 2.54 cm diameter agitator. TM A standard RZR50 mixer (Warton, Ontario, CA) was used for simple mixing and stirring at ambient temperature to achieve a stable vortex for 10 minutes. Each adhesive was then diluted with water to a solids content of 15 wt.%. Unless otherwise specified, all adhesive compositions comprise a mixture of 90 wt.% UF resin and 10 wt.% emulsion polymer on a solids basis.

[0068] Table 1: Adhesive Compositions

[0069]

[0070] * indicates a comparative example.

[0071] Table 2: Dry Tensile Strength

[0072] 1* 23.0583 0.5190 2* 25.9370 0.5548 4* 19.2560 1.4679 5* 21.6540 1.4679 7 25.7633 1.4679 8 28.5047 1.0379 9 26.3470 1.0379 10 29.5993 1.4679 11 29.6107 1.4679

[0073] * indicates a comparative example.

[0074] As shown in Table 2 above, all the high-acid emulsion polymers of Examples 7, 8, 9, 10, and 11 of the present invention are significantly superior to the comparative compositions, even those with high carboxylic acid content. An exception is Comparative Example 2, which contains n-hydroxymethylacrylamide, known to produce formaldehyde in use and in products containing it, and therefore is not substantially formaldehyde-free.

[0075] As shown in Table 3 below, all Examples 8, 10, and 11 of the present invention gave the highest or very close to the highest dilution stability rating after 48 hours, and significantly outperformed the dilution stability of Comparative Examples 1, 3, and 6, which contained simple UF resins. Comparative Example 4, which gave reasonable dilution stability, was a very soft, low-acid emulsion polymer that did not provide good tensile data, as shown in Table 2 above.

[0076] Table 3: Dilution Stability

[0077]

[0078] * indicates a comparative example.

Claims

1. A waterborne modified urea-formaldehyde resin adhesive composition comprising: based on the total solids of the urea-formaldehyde resin adhesive composition, 2.5 wt.% to less than 15 wt.% of at least one emulsion polymer as a modifier, the emulsion polymer having a pH of 4 to less than 7.0, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of acrylic acid or methacrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) one or more monomers containing olefinically unsaturated carboxylic acid groups in an amount of 5 wt.% to 25 wt.%, and further, wherein the emulsion polymer has a measured glass transition temperature in the range of -40°C to 70°C as measured by differential scanning calorimetry (DSC).

2. The waterborne modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of acrylic acid or methacrylic acid, wherein the one or more alkyl esters of acrylic acid or methacrylic acid are selected from a) butyl acrylate, ethyl acrylate, methyl acrylate, ethylhexyl methacrylate and at least one C1 to C1 alkyl ester of acrylic acid or methacrylic acid other than butyl acrylate, ethyl acrylate, methyl acrylate or ethylhexyl methacrylate. 18 A mixture of alkyl esters; or c) butyl acrylate, ethyl acrylate, methyl acrylate, ethylhexyl methacrylate having one or more vinyl aromatic monomers, and at least one C1 to C1 group of acrylic acid or methacrylic acid other than butyl acrylate, ethyl acrylate, methyl acrylate, or ethylhexyl methacrylate. 18 A mixture of alkyl esters.

3. The waterborne modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer comprises, in copolymer form, (i) one or more alkyl esters of acrylic acid or methacrylic acid, wherein the one or more alkyl esters of acrylic acid or methacrylic acid are selected from b) a mixture of any one of butyl acrylate, ethyl acrylate, methyl acrylate or ethylhexyl methacrylate with methyl methacrylate; or c) a mixture of any one of butyl acrylate, ethyl acrylate, methyl acrylate or ethylhexyl methacrylate having one or more vinyl aromatic monomers with methyl methacrylate.

4. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer comprises, in copolymer form, (ii) one or more monomers selected from acrylic acid or methacrylic acid containing olefinically unsaturated carboxylic acid groups.

5. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer comprises, in copolymer form, (ii) 10 wt.% to 20 wt.% of the one or more monomers containing olefinic unsaturated carboxylic acid groups based on the total weight of all monomers used to form the emulsion polymer.

6. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer has a measured glass transition temperature in the range of -30°C to 60°C, as measured by differential scanning calorimetry (DSC).

7. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer has a weight-average particle size of 100 nm to 500 nm.

8. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 7, wherein the emulsion polymer has a weight-average particle size of 170 nm to 400 nm.

9. The aqueous modified urea-formaldehyde resin adhesive composition according to claim 1, wherein the emulsion polymer contains less than 30% of its carboxylic acid groups in a neutralized form.

10. A method for preparing a glass fiber mat product, the method comprising: The modified urea-formaldehyde resin adhesive composition is formed from urea-formaldehyde resin and at least one emulsion polymer as a modifier, comprising 2.5 wt.% to less than 15 wt.% of the total solids of the modified urea-formaldehyde resin adhesive composition. The composition is applied to a wet-laid continuous glass fiber mat; as well as Heating to cure the composition, The emulsion polymer has a pH of 4 to less than 7.0 and comprises, in copolymer form, (i) one or more alkyl esters of acrylic acid or methacrylic acid, or a mixture thereof with one or more vinyl aromatic monomers, and (ii) one or more monomers containing olefinic unsaturated carboxylic acid groups in an amount of 5 wt.% to 25 wt.% based on the total weight of all monomers used to form the emulsion polymer, and further, the emulsion polymer has a measured glass transition temperature in the range of -40°C to 70°C as measured by differential scanning calorimetry (DSC).

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