WO2004065446A1 - Condensed urea-formaldehyde compositions and method for production of the same - Google Patents

Condensed urea-formaldehyde compositions and method for production of the same Download PDF

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Publication number
WO2004065446A1
WO2004065446A1 PCT/IL2004/000058 IL2004000058W WO2004065446A1 WO 2004065446 A1 WO2004065446 A1 WO 2004065446A1 IL 2004000058 W IL2004000058 W IL 2004000058W WO 2004065446 A1 WO2004065446 A1 WO 2004065446A1
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Prior art keywords
urea
thiourea
formaldehyde
weight percent
admixing
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PCT/IL2004/000058
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French (fr)
Inventor
Yelena Shatchin
Michael Ioelovich
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Pigmentech Ltd.
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Publication of WO2004065446A1 publication Critical patent/WO2004065446A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
    • C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
    • C08G12/04—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
    • C08G12/10—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with acyclic compounds having the moiety X=C(—N<)2 in which X is O, S or —N
    • C08G12/12—Ureas; Thioureas

Definitions

  • the present invention relates to compositions comprising water-insoluble condensed products of monomers, especially used in the paint, coating and paper industries and to a method for producing the same.
  • Urea-formaldehyde olygomers and polymers are formed by the interaction between urea [CO(NH2) 2 ] and formaldehyde [CH 2 0].
  • the urea-formaldehyde resins are viscose liquids or dried solids, which dissolves in water to form colorless syrups.
  • the liquid and dried resins are extensively used in laminates and in chemically resistant coatings. It is known in the art that various fillers added to the resin syrups make enhanced compounds suitable for various molding products, such as electro-insulating, decorative articles, etc.
  • liquid urea-formaldehyde resins are cured, at elevated temperatures and appropriate catalysts to form insoluble condensed products. These products are used as pigments for paint industry and as modifiers of cellulose materials, such as papers and boards.
  • urea-formaldehyde pigments are usually characterized as follows: a light scattering coefficient > 800 cm per g; a pore volume ⁇ 3 cm 3 per g; an average primary particle diameter in the range of 0.2 to 2.0 ⁇ ; a melting point in the range of 240 to 260°C; and a bulk density >100 g/1.
  • U.S. Pat. No. 4,960,856 to Formaini describes a method for manufacturing an aqueous solution of urea-formaldehyde precondensate.
  • This method includes the following steps: (a) reacting urea and formaldehyde at a temperature between about 65 to 90°C in the presence of acid catalyst in aqueous solution having a pH between about 3.5 and 4.25; (b) increasing the pH of the solution to between about 7.0 and 8.0 and adjusting the temperature to between about 40 to 70°C; and (c), maintaining the conditions of step (b) and continuing to react urea and formaldehyde for a time sufficient to produce said aqueous precondensate solution.
  • the molar ratio of the formaldehyde to the urea of the precondensate according to this patent is in the range of 1.20:1.0 to 1.70:1.0.
  • the condensed and powdered urea-formaldehyde resins having amorphous structure are known in the art as meso-porous sorbents characterized by high specific surface, high pore volume and high sorption capacity. These products have various disadvantages, some of which are described hereunder. Fine amorphous particles tend to agglutinate and to form coarse aggregates that decrease homogeneity, as well as optical and other physico-chemical properties of the urea-formaldehyde powders. Thus, in order to obtain the disaggregated powder, an intensive comminuting of both the amorphous urea-formaldehyde gel and of the dry product is required.
  • Amorphous powders are usually characterized by high swelling and coalescence in various liquid media, such as water, non-water solvents, etc. Furthermore, these powders significantly deteriorate the rheological properties of various emulsions and dispersions, for example of paints, varnishes, inks, coatings, pulps and other liquid products. It is thus acknowledged in the art that by owing to a high sorption capacity, commercially available amorphous urea-formaldehyde powders sorb many vapors and gases. Said sorption further worsens the industrial and the applicable characteristics of coatings cont-uning these powders and leads to defect forming, decreasing in the adhesion of the resins, lowering the decorative and protective properties of the product etc. Lastly, low density amorphous urea-formaldehyde products exhibit insufficient optical properties which reduce their market potential.
  • Said useful method contain the step of admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with sufficient formaldehyde so that its molar ratio to urea components is 0.8 to 1.2, and so that a resin precondensate viscosity of 400 to 600 cps is obtained.
  • This method is also comprised, according to one embodiment of the invention, an additional admixing step; wherein microcrystalline nucleator, 5 to 10 weight percent to final product, characterized by an average particles size of 1 ⁇ m or lower, is effectively aclmixed to the UF precondensate.
  • the aforementioned nucleator is selected from oxides, sulfides, sulfates and other insoluble crystalline substances of 2 to 4 valence metals.
  • said method is comprised of the step of precipitating the UF condensed particles from admixture contained precondensate, by means of aprotic acids, 5 to 30 weight percent to final product.
  • the said urea/thiourea composition is preferably obtained by admixing 2.5 to 10 weight percent thiourea with 50 to 60 weight percent urea in a water solution while heating to about 50 °C. It is also in the scope of the present invention wherein the formaldehyde is used in the form of a water solution comprising 30 to 40 weight percent of formaldehyde.
  • the hereto defined method comprises of the following steps: dissolving about 80 to 140 weight parts urea and about 7 to 15 weight parts thiourea in 100 weight parts water at about 50 °C; admixing about 140 to 160 weight parts of 35-37 weight percent formaldehyde solution with about 10 weight percent base solution up to about 10 to 13 pH; admixing said urea/thiourea solution with said basic formaldehyde solution and heating at agitation at about 40 to 60 °C for about 35 to 85 min until a precondensate with viscosity of about 450 to 550 cps is obtained; admixing about 0.1 to 0.6 weight percent of surfactant with said precondensate; admixing about 10 weight percent water dispersion of nucleator, having microcrystalline particles of about 0.1 to 0.9 ⁇ m in amount of about 4 to 12 weight percent to final product at about 30 to 45 °C; admixing aprotic acid dropwise to the following steps: dissolving about 80 to 140 weight
  • the base is selected from NaOH, KOH, Ca(OH) 2 or any mixture thereof; wherein the surfactant is the commercially available NP product or any of its derivatives; wherein the nucleator is selected from ZnS, TiO 2 , BaS0 4 or any mixtures thereof; and/or wherein the aprotic acid is selected from A1C1 , TiCl 4 or any mixture thereof.
  • Said product is especially preferred wherein it is characterized by white and opaque color; microcrystalline clusters with average particles size in the range of about 1 to 3 ⁇ m, crystallinity degree of about 60 to 80%, density of about 1.50 to 1.55 g per cm 3 , specific surface of less than 1 up to 3 m 2 per g and oil absorption of about 50-70%.
  • figure 1 schematically presents a block diagram of the process of making the said urea/thiourea/formaldehyde condensed compositions.
  • Said composition and all their derivatives shall be denoted in the present invention by the term 'UF'.
  • Said UF compositions are characterized by white and opaque color, microcrystalline clusters with average particle size in the range of about 1 to 3 ⁇ m, crystallinity degree of about 60 to 80%, density of about 1.50 to 1.55 g per cm , specific surface of less than 1 up to 3 m 2 per g and oil absorption of about 50 to 70 %.
  • Said method comprising admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with formaldehyde, so that its molar ratio to urea components is 0.8 to 1.2 and a resin viscosity of 400 to 600 cps is obtained.
  • said method comprising a mixture or single nucleators selected from oxides, sulfides, sulfates and other insoluble crystalline substances of 2 to 4 valence metals.
  • the hereto defined method comprising the step of precipitating UF particles from admixture containing precondensate, by means of aprotic acids, 5 to 30 weight percent to final product.
  • Fig. 1 presenting a schematic block diagram of one embodiment of the present invention providing a useful method for the production of the UF condensed composition.
  • Box (1) in the aforementioned block diagram is referring to a vessel containing water solution, comprising about 50 to 60 weight percent of urea and about 2.5 to 1.0 weight percent of thiourea. Said urea/thiourea composition is prepared while heating the solution to about 50°C.
  • Box (2) is a vessel comprising formalin - a formaldehyde aqueous solution of about 30 to 37 weight percent. Said formaldehyde solution is alkalized by any suitable alkali up to pH range of about 10 to 13.
  • Urea, thiourea and formaldehyde are admixed in predetermined ratios in reactor (3).
  • the molar range of formaldehyde to both urea and thiourea is about 0.8 to 1.2.
  • Said solution is agitated effectively when heated to about 40 to 50°C for about 30 to 90 minutes, wherein the pH is in the range of about 9 to 11.
  • An aqueous dispersion of a proper nucleator is prepared in vessel (4), so that about 10 weight percent dispersion comprising anionic surfactant at about 0,1 to 0.5 weight percent is obtained.
  • a surfactant is the commercially available NP-10 product.
  • Said dispersion is subsequently admixed to reactor (3) until the nucleator content in the final product is about 5 to 15 weight percent.
  • solutions of other reagents are prepared in vessel (4) in the presence of non-ionic surfactants. These reagents are transferred to reactor (3) to provide forming there the insoluble microcrystalline nucleator admixed with the precondesate solution.
  • Aprotic acids are defined in the present invention as salts of strong acids and weak bases.
  • Such an aprotic acid from vessel (5) is transferred to reactor (3) and slowly admixed with the precondesate at 30 to 45°C up to pH of about 3.8 to 4.0. After 15 to 30 minutes of agitation, the pH decreases to an acidic range of about 1 to 1.5. At these acidic conditions, a low viscose (about 200 to 300 cps) dispersion of the insoluble UF-particles is obtained, and the product remains under agitation for additional 30 minutes at about 30-50 °C.
  • the obtained dispersion is filtered, neutralized and washed by means of a filter (6).
  • the wet product is dried in an air-drier (7) at about 110 to 130°C.
  • the dried product is further homogenized by means of a blender (8).
  • titanium dioxide available from Ishihara Sangyo Kaisha Co., Japan
  • calcium carbonate- Avgil 510 available from K.G. Powders, Israel
  • kaolin available from Engelhard Co., USA
  • bleached sulfate cellulose available from International Paper Co., USA
  • servicingnyl 1051- binder available from Serafon Ltd., Israel
  • polyphospate disperser - Calgon N available from Benckiser-Knapsack GmbH, Germany
  • other materials available from Sigma- Aldrich and Merck Companies.
  • aprotic acid - TiC was added dropwise to the reaction system at agitation in amount of about 15% to final product. Then, the dispersion of UF-powder was held for about 30 min at 45 °C at agitation. The UF-product was separated from liquid by means of filtration, and then it was neutralized up to pH 7, washed, dried at 110 °C and treated by ball homogenizer for about 20 min.
  • the obtained UF-pigment (T-type) had the following main characteristics: Degree of crystallinity 72%, Density 1.52 g/cm 3 , Specific surface 3 m 2 /g, Average particles size 2 ⁇ m, Whiteness 97%, Oil Absorption 70%.
  • Table 1 and table 2 presents extracted characteristics of paints comprising the UF pigment as produced and defined in the present invention and by U.S. Pat. No 4,307,005. These paints having PVC value of 42% are useful for exterior finishes.
  • a significant improvement of the whiteness characteristics of the paint is obtained in paints comprising the pigments according to the present invention (about 86-88 %) as compared to the pigments produced according to the U.S. Pat. No 4,307,005 (about 81-82%). Said improved characteristics is mainly due to the very high whiteness (about 97%) of the UF- pigment produced in the method defined in the present invention.
  • Example 3 Preparation of Z - type pigment on the base of UF composition About 120 g Urea and 8 g Thiourea were dissolved in 100 ml water at about 50 °C. About 148 g 37%) Formalin was treated by 10% KOH up to pH 11 and then mixed with Urea/Thiourea solution. The reaction mixture was heated at agitation up to 50 °C and maintained for 45 min in order to obtain the precondensate with viscosity of about 400 cps. About 0.2% of NP-10 surfactant was added.
  • UF-product was separated from liquid by means of filtration, neutralized up to pH 7, and then it was washed, dried at 110 °C and treated by ball homogenizer for about 15 min.
  • the obtained UF-pigment (Z-type) had the following main characteristics: Degree of crystallinity 70%, Density 1.51 g/cm 3 , Specific surface 1.8 m 2 /g, Average particles size 2.5 ⁇ m, Whiteness 96.5%, Oil Absorption 65%.
  • Table 3 and table 4 presents extracted characteristics of paints for interior finishes comprising the UF pigment (PVC value of 80%) as produced and defined in the present invention and by U.S. Pat. No 4,307,005.
  • Example 5 Preparation of B - type pigment on the base of UF composition
  • About 95 g Urea and 15 g Thiourea were dissolved in 100 ml water at about 50 °C.
  • About 150 g 37% Formalin was treated by 5%> Ca(OH)2 up to pH 11 and then mixed with Urea/Thiourea solution.
  • the reaction mixture was heated at agitation up to 50 °C and maintained for 60 min in order to obtain the precondensate with viscosity of about 550 cps.
  • About 0.5%) of NP-10 surfactant was added.
  • the UF-product was separated from liquid by means of filtration, and then it was neutralized up to pH 7, washed, dried at 110 °C and treated by ball homogenizer for about 15 min.
  • the obtained UF-pigment (B-type) had the following main characteristics: Degree of crystallinity 60%>, Density 1.50 g/cm 3 , Specific surface 2 m 2 /g, Average particles size 2.7 ⁇ , Whiteness 96%, Oil Absorption 60%.
  • Example 6 Using the B - type pigment for paper
  • Paper samples containing compositions of bleached sulfate cellulose, Ti ⁇ 2 as a mineral pigment, kaolin as a mineral filler and UF-pigment B-type, were formed and their properties were studied. The obtained results are shown in table 5.

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Abstract

The invention relates to a method for the production of water-insoluble urea/thiourea/formaldhyde (UF) condensed composition comprising admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with sufficient formaldehyde so that its molar ratio to urea components is 0.8 to 1.2, and a resin precondensate viscosity of 400 to 600 cps is obtained. The invention additionally relates to water-insoluble urea/thiourea/formaldehyde condensed compositions. A coating and/or paper products comprising the urea/thiourea/formaldehyde condensed compositions is also disclosed.

Description

CONDENSED UREA-FORMALDEHYDE COMPOSITIONS AND METHOD FOR PRODUCTION OF THE SAME
FIELD OF THE INVENTION
The present invention relates to compositions comprising water-insoluble condensed products of monomers, especially used in the paint, coating and paper industries and to a method for producing the same.
BACKGROUND OF THE INVENTION
Urea-formaldehyde olygomers and polymers are formed by the interaction between urea [CO(NH2)2] and formaldehyde [CH20]. The urea-formaldehyde resins are viscose liquids or dried solids, which dissolves in water to form colorless syrups. The liquid and dried resins are extensively used in laminates and in chemically resistant coatings. It is known in the art that various fillers added to the resin syrups make enhanced compounds suitable for various molding products, such as electro-insulating, decorative articles, etc.
The liquid urea-formaldehyde resins are cured, at elevated temperatures and appropriate catalysts to form insoluble condensed products. These products are used as pigments for paint industry and as modifiers of cellulose materials, such as papers and boards.
Various patents have presented methods for manufacturing white powders comprising urea- formaldehyde products. Thus, U.S. Pat. No. 4,307,005 to Renner et al. claims for aqueous emulsion paint compositions. Said compositions essentially comprising of condensed urea- formaldehyde polymer as an organic white pigment, mineral pigments and fillers, a latex binder and an aqueous medium. These urea-formaldehyde pigments are usually characterized as follows: a light scattering coefficient > 800 cm per g; a pore volume < 3 cm3 per g; an average primary particle diameter in the range of 0.2 to 2.0 μ ; a melting point in the range of 240 to 260°C; and a bulk density >100 g/1.
U.S. Pat. No. 4,960,856 to Formaini describes a method for manufacturing an aqueous solution of urea-formaldehyde precondensate. This method includes the following steps: (a) reacting urea and formaldehyde at a temperature between about 65 to 90°C in the presence of acid catalyst in aqueous solution having a pH between about 3.5 and 4.25; (b) increasing the pH of the solution to between about 7.0 and 8.0 and adjusting the temperature to between about 40 to 70°C; and (c), maintaining the conditions of step (b) and continuing to react urea and formaldehyde for a time sufficient to produce said aqueous precondensate solution. The molar ratio of the formaldehyde to the urea of the precondensate according to this patent is in the range of 1.20:1.0 to 1.70:1.0. To convert the water-soluble urea-formaldehyde precondensate to insoluble particles, condensation of the precondensate at a temperature between about 55 and 80°C in the presence of mineral acid, was carried out.
The condensed and powdered urea-formaldehyde resins having amorphous structure are known in the art as meso-porous sorbents characterized by high specific surface, high pore volume and high sorption capacity. These products have various disadvantages, some of which are described hereunder. Fine amorphous particles tend to agglutinate and to form coarse aggregates that decrease homogeneity, as well as optical and other physico-chemical properties of the urea-formaldehyde powders. Thus, in order to obtain the disaggregated powder, an intensive comminuting of both the amorphous urea-formaldehyde gel and of the dry product is required. Amorphous powders are usually characterized by high swelling and coalescence in various liquid media, such as water, non-water solvents, etc. Furthermore, these powders significantly deteriorate the rheological properties of various emulsions and dispersions, for example of paints, varnishes, inks, coatings, pulps and other liquid products. It is thus acknowledged in the art that by owing to a high sorption capacity, commercially available amorphous urea-formaldehyde powders sorb many vapors and gases. Said sorption further worsens the industrial and the applicable characteristics of coatings cont-uning these powders and leads to defect forming, decreasing in the adhesion of the resins, lowering the decorative and protective properties of the product etc. Lastly, low density amorphous urea-formaldehyde products exhibit insufficient optical properties which reduce their market potential.
SUMMARY OF THE INVENTION
It is therefore the purpose of the present invention to provide a novel method for the production of water-insoluble ureathiourea/formaldehyde condensed composition. Said useful method contain the step of admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with sufficient formaldehyde so that its molar ratio to urea components is 0.8 to 1.2, and so that a resin precondensate viscosity of 400 to 600 cps is obtained. This method is also comprised, according to one embodiment of the invention, an additional admixing step; wherein microcrystalline nucleator, 5 to 10 weight percent to final product, characterized by an average particles size of 1 μm or lower, is effectively aclmixed to the UF precondensate. It is in the scope of the present invention wherein the aforementioned nucleator is selected from oxides, sulfides, sulfates and other insoluble crystalline substances of 2 to 4 valence metals. In addition, said method is comprised of the step of precipitating the UF condensed particles from admixture contained precondensate, by means of aprotic acids, 5 to 30 weight percent to final product. The said urea/thiourea composition is preferably obtained by admixing 2.5 to 10 weight percent thiourea with 50 to 60 weight percent urea in a water solution while heating to about 50 °C. It is also in the scope of the present invention wherein the formaldehyde is used in the form of a water solution comprising 30 to 40 weight percent of formaldehyde.
Thus, it is in the core of the invention wherein the hereto defined method comprises of the following steps: dissolving about 80 to 140 weight parts urea and about 7 to 15 weight parts thiourea in 100 weight parts water at about 50 °C; admixing about 140 to 160 weight parts of 35-37 weight percent formaldehyde solution with about 10 weight percent base solution up to about 10 to 13 pH; admixing said urea/thiourea solution with said basic formaldehyde solution and heating at agitation at about 40 to 60 °C for about 35 to 85 min until a precondensate with viscosity of about 450 to 550 cps is obtained; admixing about 0.1 to 0.6 weight percent of surfactant with said precondensate; admixing about 10 weight percent water dispersion of nucleator, having microcrystalline particles of about 0.1 to 0.9 μm in amount of about 4 to 12 weight percent to final product at about 30 to 45 °C; admixing aprotic acid dropwise to the reaction system in amount about 7.5 to 28.5 weight percent to final product in order to precipitate the condensed UF particles from said precondensate; maintaining said reaction system for about 30 min at about 30 to 50 °C at proper agitation; separation of the condensed UF particles from liquid by filtering; neutralization the same up to pH 7-8; washing the neutralized product; drying the product at about 110 tol30 °C; and than homogenizing the obtained product for about 15 to 25 min.
This method is especially useful wherein the base is selected from NaOH, KOH, Ca(OH)2 or any mixture thereof; wherein the surfactant is the commercially available NP product or any of its derivatives; wherein the nucleator is selected from ZnS, TiO2, BaS04 or any mixtures thereof; and/or wherein the aprotic acid is selected from A1C1 , TiCl4 or any mixture thereof.
It is still another purpose of the present invention to provide a useful water-insoluble urea/thiourea/formaldehyde condensed composition produce in the method as defined in any of the above. Said product is especially preferred wherein it is characterized by white and opaque color; microcrystalline clusters with average particles size in the range of about 1 to 3 μm, crystallinity degree of about 60 to 80%, density of about 1.50 to 1.55 g per cm3, specific surface of less than 1 up to 3 m2 per g and oil absorption of about 50-70%.
Lastly, it is another purpose of the present invention to provide cost effective and useful paint, coating and/or paper products comprising the ureathiourea/formaldehyde condensed composition as defined in any of the above.
BRIEF DESCRIPTION OF THE INVENTION
In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawing, in which figure 1 schematically presents a block diagram of the process of making the said urea/thiourea/formaldehyde condensed compositions.
DETAILED DESCRIPTION OF THE INVENTION
The following description is provided, along all chapters of the present invention, so as to enable any person skilled in the art to make use of said invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, will remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide the composition defined below.
It is thus a primary goal of the present invention to provide cost effective, white hydrophobic water-insoluble urea/thiourea/formaldehyde condensed compositions. Said composition and all their derivatives shall be denoted in the present invention by the term 'UF'. Said UF compositions are characterized by white and opaque color, microcrystalline clusters with average particle size in the range of about 1 to 3 μm, crystallinity degree of about 60 to 80%, density of about 1.50 to 1.55 g per cm , specific surface of less than 1 up to 3 m2 per g and oil absorption of about 50 to 70 %.
It is another goal of the present invention to provide a useful method for the production of the UF precondensate. Said method comprising admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with formaldehyde, so that its molar ratio to urea components is 0.8 to 1.2 and a resin viscosity of 400 to 600 cps is obtained.
It is also in accordance to another preferred embodiment of the present invention to provide a method comprising an additional admixing step; wherein microcrystalline nucleators, 5 to 15 weight percent to final product characterized by average particle size lower than 1 μm, is effectively admixed to the UF precondensate. Alternatively or additionally, said method comprising a mixture or single nucleators selected from oxides, sulfides, sulfates and other insoluble crystalline substances of 2 to 4 valence metals. According to another preferred embodiment of the present invention, the hereto defined method comprising the step of precipitating UF particles from admixture containing precondensate, by means of aprotic acids, 5 to 30 weight percent to final product.
Reference is made now to Fig. 1, presenting a schematic block diagram of one embodiment of the present invention providing a useful method for the production of the UF condensed composition. Box (1) in the aforementioned block diagram is referring to a vessel containing water solution, comprising about 50 to 60 weight percent of urea and about 2.5 to 1.0 weight percent of thiourea. Said urea/thiourea composition is prepared while heating the solution to about 50°C. Box (2) is a vessel comprising formalin - a formaldehyde aqueous solution of about 30 to 37 weight percent. Said formaldehyde solution is alkalized by any suitable alkali up to pH range of about 10 to 13.
Urea, thiourea and formaldehyde are admixed in predetermined ratios in reactor (3). The molar range of formaldehyde to both urea and thiourea is about 0.8 to 1.2. Said solution is agitated effectively when heated to about 40 to 50°C for about 30 to 90 minutes, wherein the pH is in the range of about 9 to 11.
An aqueous dispersion of a proper nucleator is prepared in vessel (4), so that about 10 weight percent dispersion comprising anionic surfactant at about 0,1 to 0.5 weight percent is obtained. One example for such a surfactant is the commercially available NP-10 product. Said dispersion is subsequently admixed to reactor (3) until the nucleator content in the final product is about 5 to 15 weight percent.
Yet according to another embodiment of the present invention, solutions of other reagents are prepared in vessel (4) in the presence of non-ionic surfactants. These reagents are transferred to reactor (3) to provide forming there the insoluble microcrystalline nucleator admixed with the precondesate solution.
Aprotic acids are defined in the present invention as salts of strong acids and weak bases. Such an aprotic acid from vessel (5) is transferred to reactor (3) and slowly admixed with the precondesate at 30 to 45°C up to pH of about 3.8 to 4.0. After 15 to 30 minutes of agitation, the pH decreases to an acidic range of about 1 to 1.5. At these acidic conditions, a low viscose (about 200 to 300 cps) dispersion of the insoluble UF-particles is obtained, and the product remains under agitation for additional 30 minutes at about 30-50 °C.
Subsequently, the obtained dispersion is filtered, neutralized and washed by means of a filter (6). The wet product is dried in an air-drier (7) at about 110 to 130°C. Optionally, the dried product is further homogenized by means of a blender (8).
It is thus according to the present invention to claim paint and/or paper products comprising the UF composition as defined in any of the above.
EXAMPLES
Various examples were carried out to prove that the embodiments claimed in the present invention are useful. Some of these experiments are described hereunder. The follows chemicals are used for the synthesis of condensed UF-compositions: urea, available from Dormex Ltd., UK; 36-37% formaldehyde solution, also know in the term Formalin, available from Frutarom Ltd., Israel; non-ionic surfactant NP-10, available from Berol Nobel Co., Sweden; thiourea, aprotic acids, alkalis and other chemicals, available from Sigma- Aldrich and Merck Companies.
The following materials were used in compositions of experimental paints and papers: titanium dioxide, available from Ishihara Sangyo Kaisha Co., Japan; calcium carbonate- Avgil 510, available from K.G. Powders, Israel; kaolin, available from Engelhard Co., USA; bleached sulfate cellulose, available from International Paper Co., USA; Servinyl 1051- binder, available from Serafon Ltd., Israel; polyphospate disperser - Calgon N, available from Benckiser-Knapsack GmbH, Germany; and other materials, available from Sigma- Aldrich and Merck Companies.
Investigations and testing were carried out by means of the following methods: viscosity of UF precondensate was checked with Brookfield viscometer. Paint coatings were applied on to opacity charts 301/2A of Sheen rnstruments Ltd., UK, using a 200 microns bar applicator. Opacity value (contrast ratio) of the dry paint coating was measured by "Sheen Opac 310" Reflectometer. Whiteness was tested using standard spectrophotometer of Dr. Bruno Lange GmbH Industriemesstechnik. Sizes and Specific Surface of UF-particles were measured by" Mastersizer -2000" apparatus of Malvern Instruments, Ltd., UK. Density of the UF-pigments was tested by picnometer-bottle method. Crystallinity of UF-pigments was calculated on the base of X-ray method of Hermans and Vonk using "Rigaku-Ultima Plus" X-ray diffractometer.
Example 1. Preparation of T - type pigment on the base of UF composition
About 100 g Urea and 10 g Thiourea were dissolved in 100 ml water at about 50 °C. About 145 g 37%o Formalin was treated by 10% NaOH up to pH 12 and then mixed with Urea/Thiourea solution. The reaction mixture was heated at agitation up to 45 °C for 70 min, in order to obtain the precondensate with viscosity of about 500 cps. Then, 0.5% of NP-10 surfactant and 10% water dispersion of Tiθ2 - nucleator having microcrystalline particles of about 0.1-0.3 μm in amount of about 5% to final UF product were introduced into the precondensate at agitation at temperature about of 35 °C. In order to precipitate of UF powder, aprotic acid - TiC , was added dropwise to the reaction system at agitation in amount of about 15% to final product. Then, the dispersion of UF-powder was held for about 30 min at 45 °C at agitation. The UF-product was separated from liquid by means of filtration, and then it was neutralized up to pH 7, washed, dried at 110 °C and treated by ball homogenizer for about 20 min. The obtained UF-pigment (T-type) had the following main characteristics: Degree of crystallinity 72%, Density 1.52 g/cm3, Specific surface 3 m2/g, Average particles size 2 μm, Whiteness 97%, Oil Absorption 70%.
Example 2. Using the T - type pigment for paints
Table 1 and table 2 presents extracted characteristics of paints comprising the UF pigment as produced and defined in the present invention and by U.S. Pat. No 4,307,005. These paints having PVC value of 42% are useful for exterior finishes.
• Table 1. Characteristics of experimental paints for exterior finishes (PVC = 42%) in paints comprising the UF pigment according to the present invention
Figure imgf000009_0001
In order to elucidate the usefulness of the compositions according to the present invention, a comparative experiment has been conducted, wherein paints for exterior finishes were produced according to the procedure described in U.S. Pat. No 4,307,005.
A significant improvement of the whiteness characteristics of the paint is obtained in paints comprising the pigments according to the present invention (about 86-88 %) as compared to the pigments produced according to the U.S. Pat. No 4,307,005 (about 81-82%). Said improved characteristics is mainly due to the very high whiteness (about 97%) of the UF- pigment produced in the method defined in the present invention.
Table 2. Characteristics of experimental paints for exterior finishes (PVC ; O ) m accordance with U.S. Pat. No 4,307,005
Figure imgf000010_0001
Example 3. Preparation of Z - type pigment on the base of UF composition About 120 g Urea and 8 g Thiourea were dissolved in 100 ml water at about 50 °C. About 148 g 37%) Formalin was treated by 10% KOH up to pH 11 and then mixed with Urea/Thiourea solution. The reaction mixture was heated at agitation up to 50 °C and maintained for 45 min in order to obtain the precondensate with viscosity of about 400 cps. About 0.2% of NP-10 surfactant was added. Then, water solutions of ZnSO4 and Na2S were introduced into the precondensate at agitation at temperature of about 35 °C to form of ZnS - nucleator having microcrystalline particles of about 0.5-0.8 μm in amount of about 10% nucleator to final UF product. In order to precipitate of UF powder, aprotic acid - 10% solution of A1C13 in ethanol, was added dropwise to reaction system at agitation in amount of about 25%) to final product. Then, the dispersion of UF-powder was held for about 30 min at 40 °C at agitation. UF-product was separated from liquid by means of filtration, neutralized up to pH 7, and then it was washed, dried at 110 °C and treated by ball homogenizer for about 15 min. The obtained UF-pigment (Z-type) had the following main characteristics: Degree of crystallinity 70%, Density 1.51 g/cm3, Specific surface 1.8 m2/g, Average particles size 2.5 μm, Whiteness 96.5%, Oil Absorption 65%.
Example 4. Using the Z - type pigment for paints
Table 3 and table 4 presents extracted characteristics of paints for interior finishes comprising the UF pigment (PVC value of 80%) as produced and defined in the present invention and by U.S. Pat. No 4,307,005.
Table 3. Characteristics of experimental paints for interior finishes (PVC = 80%) in paints comprising the UF pigment according to the present invention
Figure imgf000011_0001
A comparative experiment was conducted, wherein paints for exterior finishes were produced according to the procedure described in U.S. Pat. No 4,307,005. Here again, a significant improvement of the whiteness characteristics of the paint is obtained in paints comprising the pigments according to the present invention (about 94-95%) as compared to the pigments produced according to the US Pat. No 4,307,005 (about 88-91%). It is well acknowledged in the paint industry, that the higher the paint whiteness, the higher is its market potential. Table 4. Characteristics of experimental paints for interior finishes (PVC = 80%) in accordance with U.S. Pat. No. 4,307,005
Figure imgf000012_0001
Example 5. Preparation of B - type pigment on the base of UF composition About 95 g Urea and 15 g Thiourea were dissolved in 100 ml water at about 50 °C. About 150 g 37% Formalin was treated by 5%> Ca(OH)2 up to pH 11 and then mixed with Urea/Thiourea solution. The reaction mixture was heated at agitation up to 50 °C and maintained for 60 min in order to obtain the precondensate with viscosity of about 550 cps. About 0.5%) of NP-10 surfactant was added. Then, water solutions of BaCb and Na2Sθ4 were introduced into the precondensate at agitation at temperature of about 30 °C to form of BaSO4 - nucleator having microcrystalline particles of about 0.7-0.9 μm in amount of about 8%> nucleator to final UF product. In order start precipitation of UF powder, aprotic acid - TiCl4, was added dropwise to the reaction system at agitation in amount of about 20% to final product. Then, the dispersion of UF-powder was maintained for about 30 min at 40 °C at agitation. The UF-product was separated from liquid by means of filtration, and then it was neutralized up to pH 7, washed, dried at 110 °C and treated by ball homogenizer for about 15 min. The obtained UF-pigment (B-type) had the following main characteristics: Degree of crystallinity 60%>, Density 1.50 g/cm3, Specific surface 2 m2/g, Average particles size 2.7 μ , Whiteness 96%, Oil Absorption 60%. Example 6. Using the B - type pigment for paper
Paper samples, containing compositions of bleached sulfate cellulose, Tiθ2 as a mineral pigment, kaolin as a mineral filler and UF-pigment B-type, were formed and their properties were studied. The obtained results are shown in table 5.
Table 5. Properties of experimental paper samples
Figure imgf000013_0001
As it is follows from the results, substitution of the mineral pigment and filler with the proposed UF-pigment "B" leads to higher strength and whiteness, as well as to lower specific weight of the paper samples.

Claims

1. A method for the production of water-insoluble urea/thiourea/formaldehyde (UF) condensed composition; comprising admixing thiourea, 5 to 20 weight percent in urea/thiourea mixture, with sufficient formaldehyde so that its molar ratio to urea components is 0.8 to 1.2, and a resin precondensate viscosity of 400 to 600 cps is obtained.
2. The method according to claim 1, additionally comprising an additional admixing step; wherein microcrystalline nucleator, 5 to 10 weight percent to final product, characterized by an average particles size of 1 μm or lower, is effectively admixed to the UF precondensate.
3. The method according to claim 2, wherein the nucleator is selected from oxides, sulfides, sulfates and other insoluble crystalline substances of 2 to 4 valence metals.
4. The method according to claim 1, additionally comprising precipitating UF condensed particles from admixture contained precondensate by means of aprotic acids, 5 to 30 weight percent to final product.
5. The method according to claim 1, wherein the urea/thiourea composition is obtained by admixing 2.5 to 10 weight percent thiourea with 50 to 60 weight percent in a water solution while heating to about 50 °C.
6. The method according to claim 1, wherein the formaldehyde is used in the form of a water solution comprising 30 to 40 weight percent of formaldehyde.
7. The method according to claims 1-6, comprising the following steps: a. Dissolving about 80 to 140 weight parts urea and about 7 to 15 weight parts thiourea in 100 weight parts water at about 50 °C; b. Admixing about 140 to 160 weight parts of 35-37 weight percent formaldehyde solution with about 10 weight percent base solution up to about 10 to 13 pH; c. Admixing said urea/thiourea solution with said basic formaldehyde solution and heating at agitation at about 40 to 60 °C for about 35 to 85 min until a precondensate with viscosity of about 450 to 550 cps is obtained; d. Admixing about 0.1 to 0.6 weight percent of surfactant with said precondensate; e. Admixing about 10 weight percent water dispersion of nucleator having microcrystalline particles of about 0.1 to 0.9 μm in amount of about 4 to 12 weight percent to final product at about of 30 to 45 °C; f. Admixing aprotic acid dropwise to the reaction system in amount about 7.5 to 28.5 weight percent to final product in order to precipitate the condensed UF particles from said precondensate; g. Maintaining said reaction system for about 30 min at about 30 to 50 °C at proper agitation; h. Separation of the condensed UF particles from liquid by filtering; i. Neutralization the same up to pH 7-8; j. Washing the neutralized product; • k. Drying the product at about 110 tol30 °C;
1. Homogenizing the obtained product for about 15 to 25 min.
8. The method according to claim 7, wherein the base is selected from NaOH, KOH, Ca(OH)2 or any mixture thereof.
9. The method according to claim 7, wherein the surfactant is the commercial available NP product or any of its derivatives.
10. The method according to claim 7, wherein the nucleator is selected from ZnS, TiO2, BaSO or any mixtures thereof.
1. The method according to claim 7, wherein the aprotic acid is selected from AICI3, TiCl4 or any mixture thereof.
12. A water-insoluble urea/thiourea/formaldehyde condensed composition produce in the method as defined in claim 1 or in any of preceding claims.
13. A water-insoluble urea/thiourea/formaldehyde condensed composition according to claim 7, characterized by white and opaque color; microcrystalline clusters with average particles size in the range of about 1 to 3 μm, crystallinity degree of about 60 to 80%, density of about 1.50 to 1.55 g per cm3, specific surface of less than 1 up to 3 m2 per g and oil absorption of about 50-70%.
14. Any paint, coating and/or paper products comprising the urea/thiourea/formaldehyde condensed composition as defined in claim 1 or in any of preceding claims.
PCT/IL2004/000058 2003-01-24 2004-01-22 Condensed urea-formaldehyde compositions and method for production of the same WO2004065446A1 (en)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB275995A (en) * 1926-08-11 1929-01-10 Chem Ind Basel Manufacture of condensation products from formaldehyde and thiourea or a mixture of thiourea and urea
GB313615A (en) * 1926-08-11 1930-09-15 Chem Ind Basel Manufacture of condensation products from formaldehyde, thiourea and urea
GB344872A (en) * 1928-10-17 1931-03-12 Kurt Ripper Moulding compositions and moulded articles made therefrom
GB345845A (en) * 1929-08-29 1931-04-02 Auguste Victor Keller Improvements in or relating to varnishes and lacquers
US2009173A (en) * 1927-12-21 1935-07-23 Ciba Products Corp Artificial resin and process of making same
GB484415A (en) * 1936-11-06 1938-05-05 Aug Nowack Ag A process for the manufacture of condensation products from urea and/or thiourea and formaldehyde
US4307005A (en) * 1979-03-27 1981-12-22 Ciba-Geigy Corporation Aqueous emulsion paints contain organic white pigments
US4960856A (en) * 1988-11-28 1990-10-02 Georgia-Pacific Corporation Urea-formaldehyde compositions and method of manufacture

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB275995A (en) * 1926-08-11 1929-01-10 Chem Ind Basel Manufacture of condensation products from formaldehyde and thiourea or a mixture of thiourea and urea
GB313615A (en) * 1926-08-11 1930-09-15 Chem Ind Basel Manufacture of condensation products from formaldehyde, thiourea and urea
US2009173A (en) * 1927-12-21 1935-07-23 Ciba Products Corp Artificial resin and process of making same
GB344872A (en) * 1928-10-17 1931-03-12 Kurt Ripper Moulding compositions and moulded articles made therefrom
GB345845A (en) * 1929-08-29 1931-04-02 Auguste Victor Keller Improvements in or relating to varnishes and lacquers
GB484415A (en) * 1936-11-06 1938-05-05 Aug Nowack Ag A process for the manufacture of condensation products from urea and/or thiourea and formaldehyde
US4307005A (en) * 1979-03-27 1981-12-22 Ciba-Geigy Corporation Aqueous emulsion paints contain organic white pigments
US4960856A (en) * 1988-11-28 1990-10-02 Georgia-Pacific Corporation Urea-formaldehyde compositions and method of manufacture

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