DE2437131A1 - Storage-stable resol prepn. - by formaldehyde addn to mixt. of phenols, polyhydroxy-aryl cpds and hydroxyl gp.-contg. chromanes - Google Patents

Abstract

Storage-stable resols (single-stage alkali-condensed resins contg. methylol gps.) are prepd. by alkaline addn. of HCHO or HCHO precursors to mixts.consisting, by wt., of (a) 3-50 (10-35)% phenols, (b) 40-95 (60-85)% polyhydroxyaryl cpd. and (c) 0.5-20 (3-10)% OH gp.-contg. chromanes, where a + b + c = 100. The resols are useful for prodn. of colourless films, foils or coatings, e.g. stoving enamels, opt. in combination with 1-70 wt.% epoxide resins, melamine resins, polyesters or polycarbonated; prodn. of compressed or compression-moulded articles, opt. in combination with 80 wt.% fillers, e.g. wood, cellulose, cotton, stone, graphite, mica, asbestos or glass. Addn. of OH gp.-contg. chromanes, to phenol-contg. components before alkaline condensation, retards transition of resol to resitol, i.e. rubbery, solvent-swellable stage, without impairing reactivity in subsequent processing.

Description

Resole Resins Stable in Storage The invention relates to resole based resins of mixtures of phenols with poly (hydroxyarylene) containing chromans.

Phenol-formaldehyde resins have long been known. One distinguishes between acidic and alkaline condensed resins and, according to Baekeland, has the terms Novolaks and resols introduced for this purpose (Kunststoff-Handbuch, Volume X, Duroplasts).

Novolaks are resins that have no methylol groups have and are made acidic with an excess of phenol, while the term Resoles include those resins which have free methylol groups which cure upon heating and alkaline with an excess of formaldehyde.

Baekeland also used the designations A, B and C state for resols to indicate that the resin is of the meltable and soluble A-state (Resole) in the insoluble and rubbery, but solvent-swellable B state (Resitol) and finally into the non-melting, insoluble, solid C-state (Resit) passes.

Phenol-formaldehyde resins in the cured state are used because of them Hardness, their mechanical strength and, above all, their excellent durability against organic solvents, diluted acids and alkalis in used in large quantities for a wide variety of purposes, e.g. as foams for Insulation purposes, as cast resin plastics, molding compounds, wire coatings, adhesives, Binders and for the impregnation of fabrics.

In particular, however, the properties mentioned make the phenolic resins attractive for use in the surface protection of wood and metal. Are there known to overcome disadvantages (Kunststoff-Handbuch, Volume X, 104 ff.).

For example, hardened paint resin films are based on phenols often too brittle, so that it is mixed with those commonly used in paint technology Resins, polymers, fats, oils, etc.

must be resorted to. Also the use of substituted or etherified phenols or phenolic mixtures for the production of resoles hzw. the use of etherified resols is common to the lacquer engineering To improve properties or compatibility in mixtures.

Essentially only resols are used for surface protection, which, due to its networking, best protects the surface. Such self-hardening generally takes place through the application of heat or through the action of strong acids at normal temperature. It is often advantageous to combine both factors and by adjusting the resol solution to a certain acidic pH value the for Hardening to lower the necessary temperature (stoving temperature).

The crosslinking or curing rate of the resins continues to depend on the reactivity of the type of phenol used to prepare the resole and on the number of available methylol groups, the formaldehyde content of resol.

It is therefore often a problem to use highly reactive resol types over long periods of time Keep time stable; i.e. the transition from the resol (A) state to the resitol (B) state largely to prevent during this time, without the desired high reactivity to lose in later processing. This transition into the resitol (B) state is usually shown by a sharp increase in the viscosity of the resol solution or by gelling the clear resol solution and leads to processing difficulties, mostly even to render the resin mixture unusable.

It has now been found that this transition from the resol to the resitol state can be achieved without impairing the reactivity during subsequent processing in excellent quality Way, if the resol solution contains chromene. Particularly beneficial the use of chromans containing hydroxyl groups has proven to be the phenol-containing components are added before the alkaline condensation. As a result, the chroman is also equipped with methylol groups and during the hardening process built into the resin, so that no blistering due to segregation and exudation of the chromans can be observed at the required curing temperature.

This effect of the chromans is particularly evident in resols which from mixtures of phenols with poly (hydroxyarylene) in the presence of chromans were manufactured. Such mixtures are derived from the aforementioned reactivity and compatibility reasons are particularly interesting.

The present invention provides storage-stable resols obtained by alkaline addition of formaldehyde or formaldehyde donors to mixtures chromans contained in phenols, polyhydroxyaryl compounds and hydroxyl groups.

Another object of the invention are those from the ore in accordance with the invention Resoles produced by hardening. Resole made according to the present invention Invention, are ideal for painting metal parts. After burning in Crosslinked, colorless, easily deformable films are obtained under the usual conditions (Resite), which are particularly characterized by the fact that they are one for one-phenolic resin on metal Form a surprisingly smooth, almost crater-free surface. Another use of the resoles produced according to the invention in their use for the production of resole resin molding compounds.

After mixing with fillers, e.g. wood flour, remove the solvent and precondensation in the mixer and subsequent compression, you get bodies, which can be easily demolded and a high surface quality with excellent show mechanical properties.

The phenolic mixtures that occur in alkaline condensation are used with formaldehyde and lead to the resols according to the invention, consist of a) 3-50 percent by weight, preferably 10-35 ffi phenols, b) 40-95 Percent by weight, preferably 60-85 ffi polyhydroxyaryl compound and c) 0.5-20 Percentage by weight, preferably 3-10% chromans containing hydroxyl groups, with a) + b) + c) always results in loo.

Phenols are those with at least one free o- or

p-position of the general formula I in question.

In the general formula I. X denotes an alkyl radical with 1-12 carbon atoms, cycloalkyl radical with 4-12 carbon atoms, preferably cyclohexyl, a halogen, in particular chlorine, or an aryl radical with 6-10 carbon atoms, preferably phenyl, and n 0 or a whole Number from 1-4.

Phenol itself or alkylphenols such as o-, p-, m-cresol, o-, p-isopropylphenol, 2.6-, 2.4-xylenol, o-ethylphenol, o-, p-tert-butylphenol, Nonyl-, dodecylphenol, o-cyclohexylphenol, o-phenylphenol, o-, m-, p-chlorophenol, 6-chloro-o- Cresol and mixtures of these compounds are used.

The polyhydroxyaryl compounds used are those of the general formulas II and III.

In this general formula II, Z = alkylidene radical with 1-6 carbon atoms, a cyclohexylidene radical or a 1,3- or 1,4-diisopropylidenebenzene radical.

In the general formula III, n stands for the numbers 1, 3 or 4 and Y stands for an alkyl radical with 1-6 carbon atoms.

The following are particularly suitable as polyhydroxyaryl compounds: p, p'-methylene, p, p? -Athylidene-, p, p'-Isopropylidene-, p, p'-sec-Butylidenbisphenol and their o, p-isomers, l-methyl-1- (p-hydroxyphenyl) -6-hydroxyindane, 1,1,3-trimethyl-3- (p-hydroxyphenyl) L-hydroxyindane, 1,2,3-Trimethyl-1-ethyl-3- (p-hydroxyphenyl) -5-hydroxyindane, α, α, α ', α'-tetramethyl-α, α'-bis (p-hydroxyphenyl) -1 , 4- or -1,3-xylene, J, X, t ', K'-tetramethyl- <-bis- (p-hydroxyphenyl) -l-hydroxy-2,4- or -2,5-xylene and mixtures of these compounds.

The compounds of the formulas II and III are known. For example they can be easily removed by condensation of the corresponding carbonyl compounds manufacture with phenol. In the patents US-PS 2,775,620 (= DT-AS 1 o41 506) - or US-PS 3,221,061 (= DT-PS 1,244,796) are regulations for the Preparation of the compounds of formula II is described in US Pat. No. 2,819,249 e.g. the preparation of compounds of formula III described.

Suitable eariane are those of the general formula IV in which Y and n have the meaning given above.

Particularly suitable chromans are 2- (p-hydroxyphenyl) -4-methyl-chromane, 2,4,4-trimethyl-2- (p-hydroxyphenyl) -chromane, 2,2,4-trimethyl-4- (p-hydroxyphenyl) -chromane. These Compounds and their preparation are described in the literature.

For example, the latter chroman known as "Diamin's Compound 11, prepared by reaction of phenol with isopropenyl methyl ketone (A.P. Diamin, J. Soc. Phys.

Chim. Russe 46, 1310, (1914)).

The resols according to the invention are produced by heating the phenol-containing mixture described above in an aliphatic alcohol with C16 such as methanol, ethanol, propanol, butanol, isopropanol or isobutanol, with a 30-35% aqueous formaldehyde or formaldehyde donor solution, such as paraformaldehyde solution in the presence of a basic catalyst or by heating the alcoholic Condensation resin solution with formaldehyde and a basic catalyst, which is before or can be added during heating.

The reaction temperature is between 3o-14o0C, preferably at 5o-1170C.

The reaction time depends on the reaction temperature and the amount of catalyst. It is generally between about 10 minutes and 48 hours. The weight ratio of formaldehyde used (loo ig) to the phenol-containing Mixing is between 1: 8 and 1: 3. Inorganic ones are suitable as catalysts Bases such as lithium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonia, Sodium hydroxide together with sodium formate, sodium and potassium carbonate, barium hydroxide and mixtures of any of these catalysts. Also water-soluble organic bases such as amines, e.g. dimethylethanolamine, are suitable as catalysts. The amount of catalyst is between 0.01 and 2.5 mol per 250 g of the phenol-containing mixtures.

Working up the reaction mixture is simple. The reaction mixture is treated with a dilute acid such as sulfuric acid, hydrochloric acid, phosphoric acid, benzoic acid, Acetic acid, carbonic acid or lactic acid to a pH between 0 and 8, preferably set between 2 and 6 and evaporated or, after adding water, the organic Phase separated and up to the desired viscosity or the desired solids content evaporated in vacuo.

The resols prepared according to the invention are eminently suitable for Production of lacquer films, foils and coatings.

For this purpose, a solution of the resole, optionally with an addition of 1-70 percent by weight of another resin or polymer, such as epoxy resin (such as Epikote 1007 from Shell), melamine resins, polyesters or polycarbonates in one typical paint carriers such as methanol, butanol, isobutanol, benzene / butanol, thylacetate, Xylene, ethyl glycol acetate or methyl ethyl ketone as a thin film on a metal surface upset. The usual leveling agents can be added to the solution will.

By heating and hardening one gets colorless resites with smooth, almost crater-free surface, which adhere well, are glossy and malleable.

Furthermore, the resols prepared according to the invention are optionally suitable after mixing with up to 80 percent by weight, based on the total mixture of fillers such as wood, stone, asbestos or glass for the production of molding compounds. For example is obtained by pressing a mixture of equal parts (based on the Solids content) Resole solution and wood flour with the addition of magnesium salts molded bodies, which have a high surface quality with easy demoulding.

Example 1: 115 g of phenol and 360 g of p, p'-isopropylidenebisphenol are added under nitrogen and 50 g of 2,2-dimethyl-4-methyl-4- (p-hydroxyphenylchromane dissolved in 750 g of isobutanol and warmed to -9o0C. The pH value is adjusted to 10 with concentrated sodium hydroxide solution and 375 g of a 30% strength aqueous formaldehyde solution are added dropwise. To 3 hours at 90 ° C is cooled, diluted with 125 g of distilled water and with concentrated phosphoric acid to a pH of 3. One separates. the water off, the organic phase washes with water and, after renewed phase separation, distilled in a water jet vacuum. 91o g of a colorless resol solution are obtained, solids content: approx. 59%.

A part of this resol solution is rolled onto a sheet of metal 12 minutes at 180 ° C with the addition of 0.5 ffi 10% phosphoric acid and 3% one butylated melamine resin (such as Maprenalt MF800 from Casella-Höchst). The result is a smooth, almost crater-free, well-adhering, high-gloss and deformable paint film. The surface properties of the film are given in Table 2.

Example 2: (comparison) With a mixture of 115 g phenol and 360 The procedure described in Example 1 is used for g p, pt-isopropylidenebisphenol.

864 g of a slightly yellow resol solution are obtained, solids content: approx. 58% The storage stability of the resol solutions prepared according to Examples 1 and 2, respectively was compared and summarized in Table 1.

The viscosity according to DIN 53 211 was used as a measure of the storage stability determined by the outflow time on the filled standard beaker at 25 0C and given Outflow diameter was measured.

TABLE 1 Resole solution after resol solution according to storage-storage example 1 Example 2 time temperature viscosity at 25 0C viscosity at 250C days cc 1:21 Min./2 mm 1:45 min./2 mm O 2:28 min./2 mm 4:01 min./2 mm ß 6 6o 15: 1o min./4 mm 42:20 min./4 mm 24 6o 29:40 min./4 mm gelled 30 60 Part of this resol solution was as indicated in Example 1, processed into a paint film, the surface property of which is listed in Table 2.

Example 3: Under nitrogen, a solution of 100 g of phenol, 300 g of p, p'-ethylidenebisphenol and 40 g of 2,2-dimethyl-4-methyl-4- (hydroxyphenyl) -chromane treated as described in Example 1 in 700 g of isopropanol.

815 g of resol solution are obtained, solids content: 60%.

The resol solution showed no change after storage at 60 ° C. for 30 days their viscosity.

Example 4: lo kg of a mixture of 25 ffi phenol, 52 ffi p, p'-isopropylidenebisphenol, 10% o, p-isopropylidenebisphenol, 5% p, p'-isopropylidene-o- (p-hydroxyisopropylbenzene) bisphenol, 3% 1,1,3-trimethyl-3- (p-hydroxyphenyl) -5-hydroxyindane and 5% 2,2-dimethyl-4-methyl-4- (p-hydroxyphenyl) -chromane are dissolved in 15 kg of isobutanol under nitrogen, heated to 9o ° C and concentrated with Sodium hydroxide solution, the pH is adjusted to lo-11. Carry out slowly while stirring 7.5 kg of a 30 free aqueous formaldehyde solution and stirred for 3 hours at 90.degree. Then 3 kg of distilled water are added and the reaction mixture is cooled 70 ° C and adjusts the pH to 5-6 with phosphoric acid. One separates the Phases, the organic phase washes again with 3 kg of distilled water, separated and evaporate the organic phase at a vacuum of about 3o-5o Torr until that a solids content of approx. 70 ffi is achieved. The hot reaction mixture is pushed through a filter. Approx. 15 kg of resol solution are obtained, including after 30 days of storage at 60 ° C. no gelation could be detected.

A part of this resol solution is rolled onto a sheet of metal 12 minutes at 180 ° C with the addition of 0.5% lo pointer phosphoric acid and 3% one butylated melamine resin (such as MaprenaMF800 from Casella-Höchst). The result is a smooth, almost crater-free, well-adhering, high-gloss and deformable paint film, the surface property of which is shown in Table 2.

74.5 g of the resol solution prepared above, 47 g of wood flour (chip length 0.5 - 1 mm), 2 g of magnesium stearate and 1 g of magnesium oxide are mixed at 60 ° C and the mixture on a roller mill heated to 90 ° C. with removal of the solvent rolled out. The dry rolled skins become free-flowing and pourable granules crushed and pressed at 160 ° C to form molded parts, pressing time: 20 minutes, pressing pressure: 350 kg / cm². The resulting press bars or plates can be easily removed from the mold and have a high surface quality. The following property values were determined according to DIN 7708.

Flexural strength (kp / cm2) 680 Impact strength (kpcm / cm2) 5.8 Dimensional stability in heat according to Martens (OC) 132 surface resistance (Ohm) 4.1012 tracking resistance (Level) KA 1 Table 2 Paint film after surface assessment example 1 m 4 ni 3 / g 2 m 4 / g3 m means number of craters g means size of craters Je the smaller the measured value, the smaller the number and size of the craters.

Example 5: The procedure is as described in Example 4, however a pH of 3-4 is set with phosphoric acid and the mixture is distilled down to one Solids content of approx. 95%. About 11.5 to 12 kg of resol solution are obtained, 60 ° C is pourable and remains even when stored for more than 25 days.

Example 6: The procedure is as described in Example 4, however the isobutanol is replaced by n-butanol. The pH value is set with phosphoric acid to 1 and distilled to a solids content of 70%. 15.6 kg resole solution are obtained, their viscosity even after storage for 30 days at 600C does not increase noticeably.

Example 7: The procedure is as described in Example 4, however the pH value not with caustic soda, but with concentrated ammonia to about 9 set. About 15 kg of resol solution are obtained with a solids content of about 70%. The viscosity of the solution changes with prolonged storage at 60 ° C not.

Claims (3)

Patent claims: 1.) Resole stable in storage, obtainable by alkaline addition of Formaldehyde or formaldehyde donors in mixtures consisting of a) 3-50 percent by weight, preferably 10-35% phenols, b) 40-95 percent by weight, preferably 60-85% Polyhydroxyaryl compound and c) 0.5-20 percent by weight, preferably 3-10 X-containing hydroxyl groups Chromanians, where a) + b) + c) is always loo. 2.) Use of the resols according to claim 1, optionally in combination with epoxy resins, melamine resins, polyesters or polycarbonates for production of colorless films, foils or coatings. 3.) Use of the resinous resols according to claim 1, optionally in combination with fillers such as wood, cellulose, cotton, stone, graphite, Mica, asbestos or glass for the production of molding compounds or molded articles.