DE1495392A1 - Process for the production of granulatable unsaturated polyester - Google Patents

Description

Process for the production of granulatable "unsaturated

Unsaturated polyesters are known to be polycondensation products from ethylene-jr, ß-dicarboxylic acids or their derivatives and polyvalent ones Alcohols. Maleic acid - in the form of its anhydride - is predominantly used as the acid component. It is less common to use the stereoisomeric fumaric acid or methyl-substituted ethylene-j ^ ß-dicarboxylic acids such as mesaconic acid and citraconic acid.

In order to modify the properties of the technical end products, unsaturated and sometimes saturated products are used aliphatic or aromatic carboxylic acids.

The polyhydric alcohols are predominantly diols, such as mono- and Diethylene glycol, propylene glycol and higher homologues use.

The unsaturated polyesters can be used in monomeric vinyl, allyl or acrylic compounds and these so-called unsaturated polyester resins by means of organic peroxides and optionally Accelerators are cured to solid, insoluble and infusible three-dimensional crosslinked copolymers.

Apart from being used in the lacquer and cast resin sector liquid unsaturated polyester resins in most cases processed with fillers of various types, preferably glass fiber materials, to form reinforced thermoset moldings. The usual processing methods such as the hand lay-on method, the Vacuum and pressure bag methods, the preforming method, etc. are described e.g. in H. Hagen, Glas fiber reinforced plastics, Springer-Verlag 1961.

Unsaturated polyester, which consists only of ethylene- · ^ ß-dicarboxylic acids and ethylene glycol have been built up so far because of their poor compatibility with that commonly used as monomers Styrene and its high reactivity are of no importance for the above-mentioned areas of application

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For various technical reasons and for economic reasons However, it would be desirable to use them as a starting product for the production of free-flowing polyester molding compounds. The latter have recently been preferred for series production Smaller molded parts to be manufactured are becoming increasingly important.

In contrast to the liquid polyester resins mentioned above, they represent Ready-to-use mixtures of unsaturated polyesters, vinyl, allyl or acrylic compounds, mineral compounds Fillers, fibrous reinforcement materials such as short-cut Glass fibers, peroxide catalysts, optionally polymerization inhibitors, lubricants and dyes. In addition to technical advantages such as easy dosing, simple and efficient processing options through curing in molds under heated presses, the favorable electrical values of the cured moldings prove to be particularly valuable for the electrical industry.

In the case of a preferred method; » for the production of free-flowing Polyester molding compounds are first made into a premix from the starting materials, which is then transferred to heated mixing mills is homogenized. When the homogenization is complete, the rolled sheet is cut off and, after being pulled off, by means of a suitable Crushing machine processed into a granulate-like mass.

To obtain free-flowing polyester molding compounds and to make them more efficient The design of this process is that the starting materials for the premix, including the unsaturated polyester, are present in dry, free-flowing form required.

Monomeric acid maleic acid ethylene glycol polyesters are highly viscous to rubber-elastic masses, those made from fumaric acid and ethylene glycol, initially have a similar consistency, but tend over time Let stand for crystallization,

It was now first established that the rate of crystallization of these products depends on the molecular weight. Higher molecular weight polyesters from fumaric acid and ethyltnflycol also had more * - amorphous parts are still visible after a week's storage. With decreasing

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However, molecular weight decreased the rate of crystallization to. Pumaric acid ethylene glycol polyester with medium molecular weights of about 85O could be due to the crystallization by crystallization Due to their brittleness, they are ground into storage-stable, free-flowing granules after approx. 10 days.

This process for the production of fumaric acid-ethylene glycol polyesters which can be granulated is per se less complicated than that mentioned in British Patent 644 287 ^ffi with regard to textile impregnations, according to which batches are still one week after the end of the condensation

be kept at 85 - 90 C, but technically just as unnecessary.

A further lowering of the molecular weight in order to achieve even higher crystallization rates, however, is subject to limits for technical fields of application. As a result of the increasing content of hydrophilic hydroxyl and carboxyl end groups, the weathering and water stability of the cured molding compounds deteriorate; in the same direction, their mechanical resistance deteriorates due to the decreasing crosslinking density of the three-dimensional system. ,

The present invention relates to a process for the production of granulatable unsaturated polyesters in customary molar amounts and under customary conditions, which is characterized in that the polycondensation reaction of fumaric acid and ethylene glycol in the presence of crystallization-accelerating zinc and / or in the presence of zinc compounds in amounts 0.01 wt. -Fo based on the starting materials is carried out. The substances mentioned are preferably added to the batch mixture before the start of the polycondensation, but they can also be added at any point in time during the polycondensation. Furthermore, the catalysts mentioned can be added to the polyester which has been condensed to the desired molecular weight and is nooh in the production apparatus before it is filled. In all cases there is rapid and reproducible crystallization of the finished polyester, which has been cooled to room temperature , compared with non-catalyzed batches.

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For example, polyesters made from fumaric acid and ethylene glycol with the addition of 0.1 0.2 ia zinc dust or zinc oxide by melt condensation are average. Acid numbers of 40 and average hydroxyl numbers of from 90 corresponding to average molecular weights of about 850 etündiger 24 after approx storage at room temperature a white crystalline mass solidifies, which are tack-free to storage-stable granules softening at 90 - ground 92 ⁰ C (according to DIN 53180) permit.

On the other hand, under the same conditions without the addition of the The substances mentioned above are produced on average only after about 10 days of storage at room temperature for grinding brittleness caused by crystallization.

With increasing molecular weight, this period increases in both cases. For example, "is the corresponding storage time similarly catalyzed corresponding polyester with average acid numbers of 20 and hydroxyl numbers of 80 accordingly mean molecular weights of II50 on average 7 days. This period can be increased by choosing higher catalyst concentrations but shorten it considerably, e.g. for t? £ zinc pigeon or Zinc oxide for 2-3 days. A comparison with corresponding non-catalyzed ones Approaches - shows more than 30, an average of 39 days the efficiency of the process is particularly clear here.

In addition to metallic zinc and zinc oxide, other zinc compounds also have an effect Crystallization-accelerating effects such as aue can be seen in the examples below.

According to the concept of the invention, as starting products mainly fumaric acid and ethylene glycol used, but starting from maleic acid or maleic anhydride can also be used under certain If conditions agreed to achieve the same goal, the preparation of crystallized, granulable unsaturated polyesters.

As is well known, under the usual conditions, the Bohme1 «- condensation a conversion of the maleic acid into the fumaric acid

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configuration. However, this isomerization takes place by no means always complete, 'as is often stated in the literature

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will. In the case of polyesters made from maleic anhydride and ethylene glycol our polarograph! measurements see an average Degree of ionization of 65 #.

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By adding isomerization catalysts, such as the iodine known from DAS 1 113 087, or the cyclic secondary amines known from patent application C 29 973 IV d / 39 0 or other substances known from the literature at the beginning, during or after the polycondensation this isomerization largely complete.

Even if isomerization is not completely complete, however, occurs only after a noticeably longer time when using the inventive Catalysts crystallization, resulting in the use of maleic anhydride-fumaric acid mixtures with predominant Fumaric acid content justifies.

To modify the properties of the unsaturated polyester or to modify the properties of the derived products made from them, some of the unsaturated can be replaced by saturated aliphatic or aromatic dicarboxylic acids have been replaced; those with a symmetrical molecular structure such as adipic acid and terephthalic acid, or its derivatives, are to be preferred.

Use of asymmetrical dicarboxylic acids such as o-phthalic acid is on the other hand because of the asymmetry arising in the macromolecular structure and the resulting reduction in the tendency to crystallize only possible to a minor extent.

Part of the ethylene glycol can also be used for the same purpose other diols, also preferably symmetrical molecular structure, such as s.B. 1,4-butanediol, 1,6-hexanediol or 1,10-decanediol can be replaced.

You can polycondensation preferably in the melt at temperatures

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between I50 to 21O ⁰ C or azeotrope in an inert solvent such as xylene to be made.

The parts mentioned in the examples are parts by weight.

example 1

48?, 2 parts of fumaric acid, 286.2 parts of ethylene glycol and 0.77 parts Zinc dust is initially stored in a stirred flask for 6 hours while inert gas is passed through and the water formed is distilled off | heated to 130 C »Then the flask temperature is set in the The course of 5 hours slowly increased to 185 C and the approach at condenses at this temperature until an acid number of 39 »8 is reached. This takes 4 hours “The one with one Polyester filled in under inert gas solidified at a temperature of 150 C within 24 hours to a white crystalline hate, which can be ground non-sticky to a storage-stable, granulate.

In Examples 2-20, as in Example 1, keeping constant of all external reaction conditions, the type and amount of the catalyst varies. All polyesters were on average Acid numbers of 40 and average hydroxyl numbers of 90 condensed corresponding to average molecular weights of approx. 85O.

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Example: catalyst:

Conc. Of the cata- polyester to acid number: lysatore (wt .- $ storage stable » based on the starting granulate decomposable)

approx.

CM zinc 1.0 7 hours 38.6 3 zinc 0.2 20 hours 39.0 4th zinc 0.075 3 days 40.0 5 zinc 0.05 3 days 40.8 6th zinc 0.02 5 days 41.8, 7th Zinc oxide 0.1 1 day 38.2 8th Zinc oxide 0.1 1 day 42.6 9 Zinc oxide 0.05 3 days 40.8 10 Zinc stearate 0.1 1.5 days 42.5 11 Zinc borate 0.1 2 days 39.5 12th Zinc iodide 0.1 3 days 41.2 13th Zinc acetate 0.1 3.5 days 38.9 14th Zinc chloride 0.1 4 days 39.5 15th Zinc pyrophosphate 0.1 4 days 41.3 16 Zinc carbonate 0.1 5 days 41.1 17th Blind temptation - - 10 days 40.9 18th Blind test - - 10 days 39.3 19th Blind temptation - - 9 days 38.4 20th Blindly - - 11.5 days 42.5

In Examples 21-33, the polyesters were prepared with the addition of the aforementioned Catalysts to average acid numbers of 20 and average hydroxyl numbers of 80, corresponding to average molecular weights condensed from approx. 1150.

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BATH ORIGINAL

“Example 34

25.52 kg of fumaric acid, 15.00 kg of ethylene glycol and 0.081 kg of zinc oxide are placed in a 45 l steel apparatus (make Canzler) and heated from 20 l / h to 130 ° C. _{with stirring and introduction of inert gas (CO 0} , N _{0) and at} leave this temperature for 6 hours. The batch is then heated to 185 C over the course of 3 hours and condensed at this temperature to an acid number of 41 >> 3 over the course of 11 hours. A container filled under inert gas. The melt had solidified within about 30 hours and, after a further 24 hours, could be grinded to give storage-stable granules.

The corresponding blind test (Example 35) without zinc oxide was required with the same solidification time, a storage time of 10 days until it is grindable.

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Claims (6)

Patent claims: Process for the production of unsaturated polyesters which can be granulated from fumaric acid and ethylene glycol in the usual manner molar amounts and under usual conditions, characterized in that the polycondensation reaction of Fumaric acid and ethylene glycol in the presence of a crystallization accelerator Zinc and / or in the presence of zinc compounds in amounts from 0.01 wt .- $ £ based on the starting materials is carried out. 2.) The method according to claim 1, characterized in that instead of fumaric acid maleic anhydride and isomerization catalysts, or maleic anhydride, fumaric acid mixtures and isomerization catalysts are used will. 3.) The method according to claim 1, characterized in that instead of fumaric acid maleic anhydride fumaric acid mixtures with at least 50 $ fumaric acid content used will. 4 ·) Method according to claim 1, characterized in that some of the unsaturated by saturated aliphatic ^ or aromatic dicarboxylic acids, preferably more symmetrical Molecular structure such as adipic acid or terephthalic acid or their derivatives is replaced. 5.) The method according to claim 1, characterized in that part of the ethylene glycol by longitudinal chain, preferably symmetrical diols such as 1,4-butanediol, 1,6-hexanediol or Decanediol-1.10. 6.) The method according to claim 1, characterized in that zinc and / or zinc compounds after completion of the condensation can be added. 4.. «» B «1964 _{β0ββ03 / 1} Tat.-ibt. Br.We./Jk.