DE3241219A1 - Use of substituted phenol resins in the form of methylol compounds - Google Patents

Abstract

The use of phenol resins in the form of methylol compounds of substituted polyphenol compounds based on formaldehyde on the one hand and monovalent unsubstituted phenols on their own or together with monovalent substituted phenols on the other hand, which have been prepared by condensing these phenols in a first step to give a polyphenol novolak linked by means of methylene bridges, substituting this in a second step either with at least one substituent of the group comprising alkyl, cycloalkyl, alkenyl, terpene, aryl and aralkyl radicals and converting the substituted novolak obtained into the methylol compound in the third step by base-catalysed reaction with formaldehyde, or by immediately converting a substituted novolak obtained in the first step into the methylol compound by base-catalysed reaction with formaldehyde, in solution or solid form as binders for heat-curable coatings or impregnations.

Description

Use of substituted phenolic resins in the form of

Methylol Compounds A dispersion based on self-curing mixtures of A) epoxy resins made from diphenylolpropane and epihalohydrin and B) phenolic resins in the form of methylol compounds of substituted polyphenol compounds based on a mixture of substituted and unsubstituted phenols on the one hand and formaldehyde on the other hand in a weight ratio of A): B) = 10:90 to 90:10 suggested (P 30 41 700.6). These can be deposited with bases or electric current Dispersion contains a reaction product of the epoxy resin A) with an average Molecular weight of 300 to 30,000, preferably 500 to 20,000, with C) a secondary Amine in the form of a tertiary amine with an inorganic or a monocarboxylic acid D) is converted into a salt, the amine C) in a proportion of 10 to 100, preferably 35 to 100 equivalent percent per epoxy group has been reacted and the equivalent ratio between the tertiary amino group and the column (25 to 200): 100, preferably (50 to 175): 100.

The phenolic resins described in this earlier application could have been produced in several stages, the first stage being the condensation to one substituted, Polyphenol linked with methylene bridges, a Novolak. The ratio between (l the sum of phenols and formaldehyde for the starting materials is 1: (0.1 to 0.7), preferably 1: (0.2 to 0.65). The novolak can first be made from phenol and formaldehyde and then substituted preferably alkylated and then reacted further with formaldehyde to give the sols will.

The invention relates to the use of phenolic resins in the form Polyphenol compounds substituted by methylol compounds based on Formaldehyde on the one hand and monohydric unsubstituted phenols alone or together with monohydric substituted phenols, on the other hand, which have been produced by these phenols or phenol mixtures in the first stage to one via methylene bridges linked polyphenol novolak condenses, this in the second stage either with at least one substituent from the group alkyl, cycloalkyl, alkenyl, terpene, Aryl and aralkyl radicals substituted and the substituted novolak obtained in third Stage by base-catalyzed conversion with formaldehyde into the methylol compound has been converted, or by a substituted one obtained in the first stage Novolak directly through base-catalyzed conversion with formaldehyde into the methylol compound has been converted, in solution or solid form, as a binder for thermosetting Coatings or impregnations.

The manufacture of the end product using the novolak as an intermediate product is therefore of importance for the products to be used according to the invention because the novolak has a higher thermal stability than the resol, so that at the removal of the remaining unbound phenol by distillation does not result in further condensation entry.

For example, you can make the novolak so that you first a substituted phenol among alkaline ones Conditions with more than one mole of formaldehyde per mole of phenol to a methylol compound and this afterwards with such an amount of unsubstituted phenol that the ratio of the The sum of the phenols to the formaldehyde used is less than 1: 0.9, preferably is between 1: 0.25 and 1: 0.75.

The following substituents are used for the subsequent substitution of the novolak called: Straight-chain or branched aliphatic hydrocarbon radicals with 1 up to 18, preferably 4 to 12 carbon atoms, such as propyl, n-butyl, sec-butyl or tert-butyl, the various octyl, nonyl and dodecyl radicals or alkenyl radicals such as allyl, isopentenyl, Isobutenyl, cycloaliphatic hydrocarbon residues such as cyclohexyl, or terpene residues, aromatic radicals such as phenyl or aralkyl radicals derived from styrene, d-methylstyrene and vinyl toluene.

Suitable substituted phenols are e.g. B. alkylphenols, especially p-alkylphenols such as p-propyl- and iso-propylphenol, p-tert-butylphenol, p-octyl- and iso-octylphenol, p-nonyl and iso-nonylphenol, p-dodecylphenol, p-phenylphenol or p-cyclohexylphenol, also substituted with vinyl aromatics, especially styrene Phenols.

It is possible for the condensation to form the novolak catalysts, e.g. acids. In this case e.g. strong or weak mineral acids, but preferably organic acids such as oxalic acid, maleic acid, trichloroacetic acid, optionally also used in the form of their anhydrides. Such are to be avoided Catalysts, which mainly cause the orthostructure of the novolaks, since the formation orthostructures should be avoided if possible. The aim is for novolaks rather, a structure in which all paralignments are occupied. This remains the formaldehyde, which enters as the methylol group, is only able to be in orthoposition to enter the phenolic hydroxyl group The substituted ones Novolaks are now converted into their methylol compounds. This story through base-catalyzed reaction with formaldehyde. The formaldehyde content increases limited by the possibilities of substitution, whereby the Substtutlonsgrad'des Ndvolaks is to be considered. The total substitution should be 90% of the theoretically possible do not exceed. The theoretically possible degree of substitution results from as follows: Phenol is trifunctional for core substitution.

Due to the novolak condensation, every molecule that has entered is consumed Formaldehyde 2 possible places. The degree of substitution is calculated from the yield after distillation, assuming that all of the formaldehyde is incorporated quantitatively and is present as a methylene bridge. Are alkylated phenols is also used, the alkylation must also be taken into account. With the subsequent The same applies to alkylation. The lower limit of the formaldehyde content is variable. In order to achieve sufficient crosslinking, one is generally of the available substitution options at least 10 to 20, usually more than 30% use.

The methylol compounds are advantageously used according to the invention in a mixture with at least one plasticizing substance from the epoxy resin group, Polyvinyl acetals, polyvinyl alcohol, fatty oils, alkyd resins, polyurethanes and rubber or similar customary plasticizing substances, their share in the total solids content is usually 20:80 to 80:20, preferably 30:70 to 70:30.

The phenolic resins can also be used in the form of precondensates will. The combination with epoxy and / or alkyl resin is particularly advantageous.

Suitable plasticizing epoxy resins are, for example, the commercially available ones Epoxy resins, especially those based on diphenylolalkanes such as diphenylolmethane (Bisphenol F) and preferably diphenylolpropane (bis- phenol A) on the one hand and epihalohydrin and / or Nethylepihalohydrin, such as epibromohydrin, preferably epichlorohydrin, according to the literature (see e.g.

"Epoxy compounds and epoxy resins" Paquin (1958), page 322 ff.) described one- or two-step processes can be produced, e.g. B. such with a softening point (EP) according to Durrans of at least 700C and an epoxy equivalent weight Of at least 900.

Suitable polyvinyl acetals are, for. B. polyvinyl butyral, polyvinyl propional or similar. The fatty oils are, for example, linseed oil, soybean oil, wood oil, cottonseed oil, Sunflower oil, castor oil, cashew nut shell oil or the like can be used.

Suitable alkyd resins are, for. B. those based on phthalic acid, Maleic acid, isophthalic acid, terephthalic acid and trimellitic acid on the one hand and of naturally occurring oils or fats, e.g. those mentioned above the corresponding fatty acids or esters, e.g.

Glycerol esters of these acids. As an alcohol component of alkyd resins find e.g. dihydric alcohols such as ethylene glycol, propanediol-1,2 or -1,3, the various butanediols, oxyalkylation products of 4,4'-dihydroxydiphenyl propane, Dimethylolcyclohexane, tricyclodecyldialcohol, trihydric alcohols such as glycerine, Trimethylolethane and / or propane, and higher alcohols such as pentaerythritol, Application, individually or in a mixture.

Suitable Po: lyurethane are z. B. those of isocyanates and polyvalent ones Reaction products obtained from alcohols. Suitable types of rubber are natural rubber and the various types of synthetic rubber such as chloroprene, polybutadiene, polyisoprene, Butadiene-styrene copolymers, butadiene-acrylonitrile copomers, ethylene-propylene terpolymers or the same (hen.

The addition of alkyd resins and / or fatty oils has a plasticizing effect still further advantages, for example having a favorable elasticity of the coatings themselves. Mixtures of the additives mentioned can also be used, e.g. epoxy and alkyd resins.

The phenolic resins according to the invention are used in solution or in solid form. Examples of suitable solvents are polar solvents, such as ethers, such as dipropyl ethers, alcohols such as butanols and ethylene glycol monomethyl, ethyl or butyl ether, and ketones such as acetone and methyl ethyl ketone, respectively alone or in a mixture with one another or with aromatic and / or aliphatic, optionally halogenated hydrocarbons.

Since the phenolic resins used according to the invention are neither free phenol still contain free formaldehyde, the coatings or Impregnations with acids and / or are crosslinked at elevated temperature, with no or at most traces of pollutants are split off. This represents one is a significant advantage over the use of the previously common resols.

"Coatings" can also be used as adhesive layers be understood.

Woven and knitted fabrics can be used as a substrate for impregnation Fibers or nonwovens, e.g. B. those from organic, - especially synthetic - and / or mineral fibers are used.

The crosslinked coatings obtained are tasteless, i.e. they give no flavors off. They can be used, for example, as varnishes that contain food and beverages, Drinks or drinking water come into contact, serve. Here are in contrast no very high stoving temperatures or long stoving temperatures compared to the previously used resols Burn-in times are noble to avoid any taste-causing substances from the paint film to remove. The burn-in temperature of the one obtained according to the invention very quickly crosslinking lacquers can therefore be chosen as low as the crosslinking behavior is equivalent to. On the other hand, the invention allows that at any high crosslinking temperatures, z. B. in shock drying, very short times are sufficient for complete crosslinking.

Such a procedure was previously used when using the known fast-curing Phenolic resols, e.g. B. such.

from meta-cresol and formaldehyde, which in their cross-linking behavior correspond approximately to the resins used according to the invention, not possible. With the so far The resins used were namely a long stoving time or a high stoving temperature the decisive criterion for the removal of the substances that cause the taste for the selection of the stoving conditions.

For the use of resoles, the tolerance is usually with other raw materials, especially paint and adhesive raw materials of crucial This is important because the new resins are mainly used on the paintwork and Adhesive area takes place. The compatibility is usually achieved by incorporating Cresol and by etherification of the methylol groups of the resins with alcohols, especially with butanol. This increases the compatibility, but the networking amount Impaired speed. in contrast, those used according to the invention show Resoles of anchors are very good, adjustable by the degree and type of substitution Compatibility with other raw materials. Hence the etherification of the methylol groups cease and the high crosslinking speed is maintained.

Despite the very high crosslinking speed of the resins used it is very surprising that these have an extremely good shelf life. in the In general, phenol resols, particularly those which crosslink quickly, are poorly storable and become unusable after a few months. It was therefore not to be expected that the resins used according to the invention, e.g. in solution even over a period of time are stable for years and even after that the coatings will still harden perfectly and impregnations with good properties. For example, a 60% Solution of the following methylol compound B stored for 2 years at room temperature the viscosity does not increase. At the beginning of the storage period the Viscosity 1150 mPa.s / 200C, at the end 1175 mPa.s / 20 ° C. Even an 11-month storage at 500C the viscosity increased from 1150 mPa.s / 20 ° C to only 2000 mPa.s / 200C. As further tests showed, this is Har: even after these extreme storage conditions Unreservedly usable as a tin can varnish.

In the experiments and examples below, T is parts by weight and% weight percent. The viscosity of the resins was, unless otherwise stated, 50% in each case in ethylene glycol monoethyl ether at 20 ° C.

I) Preparation of the methylol compounds A) Arvlsubstitui.ertes resol a) Production of the novolak: In one with stirrer, thremometer, heating, cooling, device for distillation and device for circulating distillation under reduced pressure equipped reaction vessel were 1134 parts of an aqueous 37% formaldehyde solution, 600 parts of xylene and 1190 parts of p-phenylphenol suspended and heated to 60.degree.

At this temperature, 420 parts of aqueous sodium hydroxide solution (33%) were run in and react with stirring until the formaldehyde content was 0.8%. The approach was then neutralized with 700 parts of 25% strength sulfuric acid and adjusted to pH 3.0. After settling, 1693 T of lower layer (saline solution) are separated off. The approach was washed with water, treated with 2632 T phenol after separation and under Normal pressure azeotropically with recirculation of the solvent distilled. By leaving separation Part of the circulating agent xylene was allowed to raise the temperature to 220.degree. 419 T aqueous phase separated out. It was then distilled under reduced pressure The pressure was 1 hour at 2200 ° C. and received a total of 2330 T of distillate. In the reaction vessel 2118 parts of a phenyl-substituted novolak remained, melting point 87 ° C., viscosity 281 mPa.s / 20 ° C.

b) Preparation of the methylol compound 662-T of that obtained according to a) Novolaks were melted and heated to 1206C. At this temperature they gave 240 parts of 33% sodium hydroxide solution and 180 parts of water are added. The melt was cooled to 60 ° C, 227 T aqueous 37% formaldehyde are added while stirring and. 5 hours at 60 ° C stirred. After that, no more free formaldehyde was detectable. The approach was Diluted with 520 parts of isobutanol and 50 parts of xylene and with 380 parts of 25% sulfuric acid adjusted to pH 5.0. After the lower layer had been separated off, it was mixed with 500 T of water washed. The batch was recycled by distillation under reduced pressure dehydrated of the solvent at a sump temperature of 50 ° C. There were 411 T water on. 1107 parts of a 66.3% strength resin solution remained in the flask, viscosity 4540 mPa.s / 20 ° C.

B) Aralkyl-substituted resol a) Production of the novolak: In one with thermometer, stirrer, reflux condenser, descending condenser and device for Reaction vessels provided with reduced pressure were applied, 67 parts of phenol 0) 4 m maleic anhydride and 29.11 T 37Hige aqueous formaldehyde solution for 3 hours on Refluxed. Then you apply reduced pressure and distill the volatile components up to a bottom temperature of 220 ° C. In the reaction vessel 49.9 T of a phenol novolak remained with a viscosity of 290 mPa.s / 200C. Free phenol content 0.01%.

33.55 T of the novolak obtained was melted and concentrated with 0.1 T Sulfuric acid added. To the melt, which was kept at 80 ° C., were added 17.22 parts of styrene, let the temperature rise to 120 ° C and held this temperature for another hour.

the b) Preparation of the methylol compound: To the product according to a) were 18.44 rr 35% sodium hydroxide solution and iLl, 88 parts of water, cooled to 60 ° C and mixed with 18.76 parts of a 37% strength aqueous formaldehyde solution. After 3.5 hours free formaldehyde was no longer detectable. Then you dilute the melt with 36.69 T isobutanol and 4.13 T xylene and neutralized with 16.12 T 50% sulfuric acid.

After separating off the aqueous phase, dehydration was carried out as under A, b Circulating distillation under reduced pressure and obtained 96 parts of a 60% strength resin solution with a viscosity of 1150 mPa.s / 200C.

Examples 1) From 9 parts of a 50% strength solution of a commercially available epoxy resin based on diphenylolpropane and epichlorohydrin (epoxy equivalent weight approx 2000) in Ethylenglykolmonoäthyläther, 27 T of the Methy lolverbindungen B, 1.5 T of one serve phosphoric acid solution in n-butanol, 7 T diacetone alcohol, 7, -5 T one predominantly Hydrocarbon mixture consisting of ethylbenzene. (Boiling point 2500C) and 7.5 T Ethylene glycol monoethyl ether became a thermosetting mixture with a solids content produced by about 41%. This mixture was rolled onto a pad applied from tin-plated steel sheet and the resulting 6 µm thick coating on top Burned in for 10 to 15 minutes at 1900C.

Result of the paint test The coating obtained in this way was subjected to the paint test with the following result: Acetone test 100 double wipes Color medium gold tone Deep-drawing toughness value 0 = perfect (cell pull) Cross-cut Value 0 = perfect test sterilization value 0 = perfect resistance: 2% lactic acid (1 h / 121 ° C) water vapor value 0 = perfect sterilization (1st h / 121 ° C) 2) 6.5 T of methylol compound E, 4 T of pure zinc yellow, 2.6 T of zinc tetrachromate, 1.1 T talc, 1.1 T iron oxide pigment, 2.2 T zinc phosphate, 1 T carbamic acid ester resin, 3 T finely divided silica (10% paste in xylene), 5.5 T ethanol, 71 T polyvinyl butyral were mixed and in a solution medium mixture of ethanol, ethyl acetate and toluene (1: 1: 1) processed further as a 12.7% solution.

This solution was made with 1 T phosphoric acid in 1 T n-butanol offset and the coating mixture obtained in this way by spraying with a layer thickness of 30 up to 35 tjm applied to sheet steel.

The crosslinking was carried out by leaving it in the air at room temperature. The paint film obtained showed none after 3 days of storage in the presence of water Change. In the tropical test according to DIN 50 017, the film showed the best possible after 10 days Value. The test according to ASTM B 117/64 (salt spray test) also showed the same 10 days the best possible value.

3) 100 parts of a slightly discoloring butadiene-acrylonitrile copolymer (Mooney plasticity ML-4 '1000C: 65 + 7) with about 39% acrylonitrile content (solid) were with 45 T methylol compound A, b and 500 T of a mixture of 3 T ethyl acetate, 1 T acetone and 1 T toluene combined. This mixture was suitable as an adhesive, e.g. For gluing floor coverings made of polyvinyl chloride, such as those with plasticizer content.

3 V) (comparison) The procedure was as in Example 3, but without Harz A.

Adhesive test The results obtained according to Example 3 and Comparison 35I) Mixtures were applied as an adhesive using a brush on test strips measuring 2 × 10 cm Applied length made of commercially available polyvinyl chloride with 10% plasticizer content.

After waiting times of different lengths - to determine the contact tack time the adhesive layers were put together and pressed together for 10 seconds at 3 bar.

After different flash-off times at 200C and 90 ° C the bonds were made on a tearing machine suitable for the test area at a feed rate of 180 mm / min for separation strength at room and elevated temperature checked.

The results are shown in the table in which the values show the separation strength Specify in N / cm. The series of tests for 10 minutes of ventilation at 90 ° C. shows that due to the addition according to the invention, advantages over this even when venting at 90.degree can be achieved according to the state of the art.

Table result of the adhesive test - release strength, flash-off time 10 min 1 h 3 h 10 min 10 min venting temperature 20 ° C 20 ° C 20 ° C 90 ° C 90 ° C Age of the bond ------------- 3 days test temperature 20 ° C 20 ° C 20 ° C 20 ° C 50 ° C Example 3) c5 29 31 23 Lt 3V) (comparison) "- II 1 - = no bonding possible, adhesive film dry completely.

Claims (2)

PATENT SEARCH: 1) Use of phenolic resins in the form of methylol compounds substituted polyphenol level bonds based on formaldehyde on the one hand and monohydric unsubstituted phenols alone or together with monohydric substituted ones Phenols, on the other hand, which have been prepared by using these phenols hzw. Phenolic mixtures condensed in the first stage to a polyphenol novolak linked via methylene bridges, this in the second stage either with at least one substituent from the group alkyl, - Cycloalkyl, alkenyl, terpene, aryl and aralkyl radicals substituted and the obtained Substituted novolak in the third stage through base-catalyzed reaction with formaldehyde has been converted into the methylol compound, or by a first stage Substituted novolak obtained by base-catalyzed reaction with formaldehyde has been converted into the methylol compound, in solution or in solid form as Binders for thermosetting coatings or impregnations. 2) Use according to claim 1, characterized in that the phenolic resin mixed with a plasticizing substance from the epoxy resin, polyvinyl acetal group, Polyvinyl alcohol, fatty oils, alkyd resins, polyurethanes and rubber are used, preferably in combination with epoxy and / or alkyd resin.