RU2026309C1 - Process for preparing modified aminoformaldehyde resins - Google Patents

Abstract

FIELD: chemical and timber chemical industries. SUBSTANCE: the process for preparing modified aminoformaldehyde resins involves combined condensation of amine, phenol and formaldehyde in a 1:(0.01-0.03):1.89-3.0 molar ratio on heating in variable media, the final amine to formaldehyde molar ratio being 1: (1.15-1.45). EFFECT: improved properties of the modified resins. 2 tbl

Description

 The invention relates to the chemical and wood chemical industries and, in particular, to the field of production of modified aminoformaldehyde resins used in the manufacture of paper and resin films intended for the decoration of wood boards, the manufacture of laminated plastics, as well as for gluing furniture parts and the production of plywood.

 At present, urea-formaldehyde resin-based impregnating compositions are known. Urea-formaldehyde impregnating resins are mainly used in the production of films with full polycondensation of the resin (synthetic veneer) 33 [1].

 However, these resins, possessing good penetration and fast curing, do not protect the surface of panels and plywood from moisture, therefore, after lining with films of wood boards or plywood, the surface is coated with nitro or polyester varnishes.

Impregnating rezole phenol-formaldehyde resins are known, obtained by condensation of phenol and formaldehyde in a slightly alkaline medium. Phenol-formaldehyde resins impregnate mainly special types of kraft papers with a surface density of 40-200 g / m ² [2].

 The disadvantage of this type of resins is their instability during long-term storage, reduced penetration and toxicity, because they contain up to 2.5% free phenol. In addition, alcohol solutions of resol resins are used for paper impregnation, which makes the production of fire and explosion hazard.

 It is known to obtain thin transparent and elastic coatings of steel sheets by homogeneous mixtures based on diphenylol propane along with other substances (pigments, hardeners, fillers, graphite, solvents) with aminos or their reaction products with methanol, polycarboxylic acids or their derivatives, urea, epichlorohydrin, alkyd resins, polyester resins and / or styrene-containing polyesters. The homogeneous mixture contains from 5 to 200% diphenylolpropane (bisphenol A) [2].

 The technology for producing these products is complex and time-consuming, requires the prior preparation of hexamethoxymethylmelamine, and the final products are viscous, unsuitable for the impregnation of paper sheets.

A known method of producing modified aminoformaldehyde resins based on aminotriazines, formaldehyde and oxyalkylated diphenylol propane, which is introduced in an amount of 0.025-0.1 moles per mole of aminotriazine [3]. The resulting resins are distinguished by good physical and mechanical properties, but the technological properties are insufficient, they have a short shelf life (15-19 days), more viscous (21-25 s), which makes it difficult to impregnate at high speeds and high density papers, a reduced curing rate at 150 ^о С - 500-600 s, moreover, these are alcohol solutions.

There is also a method of obtaining an impregnating water-soluble phenol-formaldehyde resin obtained on the basis of phenol (100 parts by weight), formaldehyde (37% solution 25-27), urea (5-45), caustic sodium (technical 42% solution 25 -27) and triethanolamine (1-10). The process is carried out by polycondensation of phenol with formaldehyde in the presence of alkali, with a gradual adjusting the reaction mixture to the reflux temperature and aged for 10-15 min followed by cooling to 30 ^C. The reaction mixture is boiling urea while cooling the reaction mass to ^about 70-75 C, then additionally sodium hydroxide is added in an amount of 40% of its total mass. Then triethanol amine was added and condensation continued at 50-55 ^{° C} for 5-15 min [4]).

 The resulting impregnating resins have a low dry matter content (40 ± 2%), which poorly provides the necessary resin gain when passing through the impregnation machine, contain a lot of free phenol (0.8-0.95%) and have a long curing time.

 A known method of producing phenol resins resins modified with urea [5] used for the impregnation of papers and fabrics. The resins are obtained by copolycondensation of a mixture based on phenol, urea and formaldehyde, carried out at normal pressure in the presence of inorganic acid catalysts with a molar ratio of phenol plus urea to formaldehyde 1: <0.8, with the urea portion in phenol plus urea being ≅ 50 mol%, followed by the polycondensation reaction of the resulting copolycondensate with added formaldehyde, carried out in the presence of an alkaline catalyst at pH> 7. The amount of formaldehyde introduced in the alkaline polyconde stage sation such that the molar ratio of phenol plus urea is 1:> 1. Then, a large part of the water of reaction and unreacted monomers are distilled off.

 Resins are stable for 14 days. These are alcohol solutions, which worsens the ecology of the production of paper-resin films.

 Wastewater present in the technology of this production contains free phenol and formaldehyde, which requires significant costs for their disposal.

 The aim of the invention is to obtain a modified urea-formaldehyde resins with reduced toxicity, increased curing rate and stability of storage properties.

 The essence of the invention lies in the fact that the polycondensation of amine, diphenylolpropane (bisphenol A) and formaldehyde is carried out in a molar ratio of 1: (0.10-0.30) :( 1.89-3.0), and the final ratio of amine and formaldehyde is 1: (1.15-1.45).

 Diphenylolpropane used for the synthesis of the proposed resins is produced in the USSR in accordance with GOST 12138-86.

 The proposed method for the production of diphenylolpropane-modified urea-formaldehyde resins can be carried out in two ways.

 Option A.

The condensation of urea and formaldehyde in a molar ratio of 1: (1.89-3.0) in an alkaline medium at 96-98 ^about C.

Co-condensation with diphenylolpropane in an acidic or alkaline conditions at 80-96 ° ^C. with an additional decondensation amine in an alkaline medium, wherein the amine is used in such an amount to provide a final ratio of amine to formaldehyde of 1: (1.15-1.45). As amines, mainly urea, melamine or mixtures thereof can be used.

 Option B.

Joint urea condensation, diphenylolpropane, and formaldehyde in an alkaline medium in the presence of a solvent or without at 80-98 ° ^C. The polycondensation under acidic conditions at 96-98 ° ^C.

 Subcondensation with an additional amount of amine in an alkaline medium at a final molar ratio of amines to formaldehyde of 1: (1.15-1.45). As amines, for example, carbamide and melamine or mixtures thereof are preferably used.

Resins obtained by the proposed technical solution are low toxic, that is, they do not contain free phenol, do not contain a large amount of free formaldehyde up to 0.5%. A high content of dry matter mass fraction of 52-66%, high speed curing, with 1% NH ₄ Cl at ¹⁰⁰ ° C - 32-96 s. and in the absence of the curing agent at 150 ° ^C - 90-125 s, characterized by a wide range of viscosities from 13 to 190 with VZ-4 and are stable on storage for months. Upon receipt of the impregnating resins there is no wastewater, which does not require their additional disposal, the process is environmentally friendly. Upon receipt of adhesive resins, it is necessary to concentrate the resin to a mass fraction of solids of 60-66%.

 The proposed diphenylolpropane-modified urea-formaldehyde resins when impregnated with plain paper, printed paper canvases, fabrics do not change the color of paper and fabrics, do not erode the printed pattern applied with water-soluble inks. These resins provide high quality lining materials of light colors.

 The essence of the invention is the creation of a new method for producing new impregnating resins based on the products of joint polycondensation of urea, diphenylolpropane and formaldehyde under their specific ratios and synthesis conditions. The new significant distinguishing features are: the use of diphenylolpropane in joint polycondensation with urea and formaldehyde, their molar ratio (0.01-0.03): 1: (1.89-3.0), respectively, with the final molar ratio of amine to formaldehyde is 1: (1.15-1.45). Similar urea-formaldehyde impregnating resins, i.e. based on the products of the joint condensation of urea, diphenylolpropane and formaldehyde, are unknown in the scientific and technical literature.

 Option A.

PRI me R 1. In a reactor equipped with a stirrer, reflux condenser and jacket for cooling and heating, load 423 g of a 33.5% concentration of formalin and adjusted to pH 5.0 with aqueous ammonia of 25% concentration. The neutralized formalin while running the stirrer was charged with 150 g of urea was heated to 96-98 ^{° C} and kept at this temperature until the hydrogen ion concentration pH of 5.0. The reaction mixture was cooled to 80 ^C and charged with 15 g of diphenylolpropane, condensation continued at this temperature for 0.5 hours, after which the temperature is lowered, raising the pH to 7.5 and additional urea is administered in an amount of 36.5 g

 Condensation is carried out and the finished resin is cooled. The properties of the obtained resin are given in table 1.

PRI me R 2. In the reactor according to example 1 load 830 g of a 36% aqueous solution of formaldehyde, aqueous ammonia of 25% concentration, the pH of the medium is adjusted to 8.1 and 300 g of urea are introduced. The reaction mixture is heated to 96-98 ^about C and kept at this temperature until the pH of the condensation solution is equal to 5.3. The reaction mixture was cooled ^to 85 ° C, are introduced 45 g of diphenylolpropane and condensation continued at this temperature for 0.5 hours. Then, the temperature was lowered to 70 ^C, raised 1N. caustic soda pH to 7.5 and add additional urea in an amount of 110.4 g. The reaction mixture is condensed and the finished impregnating resin is cooled and poured into a container. The properties of the resin are given in table 1.

PRI me R 3. In the reactor according to example 1 load 448 g of 33.5% formalin, with an aqueous solution of ammonia of 25% concentration, the pH of the medium is adjusted to 8.5 and 150 g of urea are introduced. Then the reaction mixture is heated to 96-98 ^about C and kept at this temperature until the concentration of hydrogen ions reaches a pH of 5.1. Then the reaction mixture is cooled to 80 ^° C, the pH of the medium is raised to 8.4, and 15 g of diphenylolpropane are introduced. The condensation is continued for 1.5 hours at 80 ^C. The mixture was then cooled ^to 65 ° C and introduced 38.4 g of additional urea and condensation continue. The properties of the resin are given in table 1.

Example 4. 448 g of 33.5% formalin are charged into the reactor of Example 1, a pH of 8.0 is adjusted with an aqueous solution of ammonia of 25% concentration and 150 g of urea are introduced. Then the reaction mixture is heated to 96-98 ^about C and maintained at this temperature until the concentration of hydrogen ions reaches a pH of 5.3. The reaction mixture was cooled ^to 85 ° C, the pH is raised to 8.5, are introduced 37.5 g of diphenylolpropane and condensation continued for 1.5 hours at 90-95 ^C. The reaction mixture was cooled to ⁷⁰ ° C, introduced into the second a portion of urea in the amount of 31.8 g and is condensed to obtain the finished resin, which is cooled. The properties are given in table 1.

PRI me R 5. 1184 g of 34.2% formalin, 300 g of urea are loaded into the reactor, and the pH of the medium is adjusted to 8.5 with 25% aqueous ammonia. Then the reaction mixture is heated to 96-98 ^about C and maintained at this temperature to a pH of 4.3. Then the reaction mixture is cooled to 80 ^about With, raise with 1 N. sodium hydroxide to pH 8.1, is introduced 45 g of diphenylolpropane and condensation continued at 85 ^{° C} for 1.5 hours. The reaction mixture was cooled ^to 65 ° C and introduced 222.6 g of additional urea, the reaction mixture was post-condensed, cooled and drained. The properties are given in table. 1.

Example 6. 1316 g of 34.2% formalin, 300 g of urea and a 25% ammonia solution were charged into the reactor. The pH of the medium was adjusted to 8.5. Then the mixture is heated to 96-98 ^about C and kept at this temperature until the pH of the medium drops to 4.4. The reaction mixture was cooled to ⁸⁰ ° C, are introduced 60 g of diphenylolpropane and condensation continued at this temperature for 0.5 h. Thereafter, the temperature was lowered to 60 ^C, raised the pH to 8.3 and additional urea is administered in an amount of 312 2 g. Conduct condensation, the finished resin is cooled and drained. The properties are given in table 1.

Example 7. 830 g of 36% formalin, 300 g of urea and 25% aqueous ammonia were charged into the reactor. The pH of the medium was adjusted to 8.4. Then the reaction mixture is heated to 96-98 ^about C and at this temperature the mixture is maintained until a pH of 5.2 is reached. Then the reaction mixture is cooled to 80 ^° C, the pH of the medium is raised to 9.0, and 11.5 g of diphenylolpropane are introduced. Condensation at this temperature was continued for 1.5 hours. Then, 178.9 g of melamine was added and then condensed. The finished resin is cooled and drained. The properties are given in table 1.

 Option B.

PRI me R 8. In the reactor load 417 g of 36% formalin, 25% aqueous ammonia set the pH of the medium to 9.5. 150 g of urea and 22.8 g of diphenylolpropane are introduced into the neutralized formalin with stirring. Further, as in example 1, the mixture is heated to 96-98 ^about C and conduct condensation to achieve an acidic medium pH of 5.2. Then the condensation product is cooled to 70 ^about With, raise 1 N. a solution of caustic soda pH to an alkaline medium and an additional amount of urea is introduced 89.4 g. Condensation is continued until a finished resin is obtained, it is cooled and drained. The properties of the resin are given in table 1.

PRI me R 9. In the reactor load 909.7 g of 37.0% formalin, neutralize 1 N. alkali solution to pH 9.0. 300 g of urea and 30 g of diphenylolpropane are introduced into the neutralized formalin with stirring. The reaction mixture was heated to 80-83 ^{° C} and kept at this temperature for 40 min. Then, a 3.0% hydrochloric acid solution is introduced into the reaction product until the acidic medium reaches pH 4.8 and condensation is continued until the viscosity of the reaction solution reaches 16 s. The resulting condensation solution is cooled to 60 ^° C., 1N is introduced. caustic soda solution to pH 8.25 and load additional urea in the amount of 165.5 g. Condensation is continued until the resin is ready, it is cooled and drained. The properties are given in table 1.

PRI me R 10. In the reactor load 3245 g of 37% formalin, neutralized with 10% sodium hydroxide solution to a pH of 9.0. 1126 g of urea and 291.8 g of diphenylolpropane are introduced into the neutralized formalin with stirring. Then the reaction mixture is heated to 80-85 ^about C and at this temperature can withstand 40 minutes Further, the reaction product was added 10% ammonium chloride solution to pH 5.2 and condensed at 96-98 ^{° C} until a viscosity of 18 to the solution. Condensing the resulting solution was cooled to ⁸⁰ ° C, are introduced 10% caustic solution to pH 7.9 and additional urea are charged in an amount of 410 to continue condensation resin readiness, cooled and decanted. The properties are given in table 1.

 PRI me R 11. In the reactor load 909.7 g of 37.1% formalin, neutralize 1 N. alkali solution to pH 9.0. 440 g of isopropyl alcohol, 300 g of urea and 342 g of diphenylol propane are loaded into the neutralized formalin with stirring.

The reaction mixture is heated to boiling point and maintained at this temperature for 30 minutes. Further, the reaction product was introduced into 10% ammonium chloride solution until acidic to pH 3.4 and continued condensation to achieve a solution viscosity at 16 with B3-4 at 20 ± 1 ° ^C. The resulting condensation solution was cooled to ⁶⁰ ° C, injected 1 N. alkali solution to pH 8.25 and load additional urea in an amount of 60 g. Condensation is continued until the resin is ready, cooled and drained.

Example 12. 417 g of 36% formalin was charged to a reactor, and a pH of 10 was adjusted with 25% aqueous ammonia. 192 g of melamine and 22.8 g of diphenylolpropane were introduced into the neutralized formalin with stirring. Next, the mixture is heated to 80-82 ^about C and conduct condensation until an acidic medium is reached (pH 5.2). Then the condensation product is cooled to 70 ^about C, create 1 N. caustic soda solution, an alkaline medium equal to 7.0-7.5, and an additional 96 g of urea are introduced and condensation continues. After the resin is cooled and drained. The properties of the resin are given in table 1.

PRI me R 13. In the reactor load 417 g of 36% formalin, aqueous ammonia of 25% concentration, the pH of the medium is adjusted to 8.0 and 150 g of urea are introduced. Then the reaction mixture is heated to 96-98 ^about C and maintained at this temperature until a pH of 5.0 is reached. Next, the reaction mixture is cooled to a temperature of 80 ^about With, raise the pH of the medium to 9.0 and enter 22.5 g of diphenylolpropane. The condensation is continued for 1.5 hours at 80 ^C. The mixture was then cooled to ⁶⁰ ° C and further introduced 38.4 g of urea. Condensation is continued for 30 minutes, after which water and low molecular weight products are distilled off to a mass fraction of dry matter of 60%.

 The properties of the resin are given in table.2.

PRI me R 14. In the reactor load 448 g of 33.5% formalin, neutralize it with 10% sodium hydroxide solution to a pH of 9.0. 150 g of urea and 22.5 g of diphenylolpropane are introduced into the neutralized formalin with stirring. The reaction mixture was heated to 96-98 ^{° C} and kept at this temperature for 40 min. Further, the reaction product was added 10% ammonium chloride solution to pH 5.1 and condensed at ^about 96-98 C until the viscosity 23 s. The resulting condensation solution is cooled, a 10% alkali solution is introduced to pH 7.5, additional urea is added in an amount of 38.4 g and the vacuum is turned on. Drying of the resin under vacuum continues until the content of the mass fraction of dry matter 66.7%. The properties of the resin are given in table.2.

 As can be seen from the proposed examples and the data of tables 1 and 2, the resin can be from white to light yellow in color, differ in a wide range of viscosities, do not contain free phenol, are low toxic, because contain no more than 0.5% free formaldehyde, are stable in time, and have a high curing rate. The proposed resins can be used to produce lining materials similar in properties to lining materials based on melamine-formaldehyde resins, and can also be used as adhesives for gluing furniture parts and in the manufacture of plywood.

Claims (1)

 METHOD FOR PRODUCING MODIFIED AMINO-FORMALDEHYDE RESINS by means of joint polycondensation of amine, phenol and formaldehyde when heated in variable media, characterized in that diphenylolpropane is used as phenol, and polycondensation is carried out at a molar ratio of amine, diphenylolpropane: 1.89 - 3.0, while the final molar ratio of amine to formaldehyde is 1: 1.15 - 1.45.

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