NO782921L - EVAPORATION WEAK, WELL OVERLAMINARABLE, CURABLE UNSATATED POLYESTER RESINS - Google Patents

Abstract

"Evaporative weak, well overlaminable, curable unsaturated polyester resins"

Description

The invention relates to low-evaporation, in the presence of common polymerization initiators curable, well-overlaminated, unsaturated polyester resins of an ethylenically unsaturated polyester, a copolymerizable, ethylenically unsaturated monomeric compound as well as possibly further building components and auxiliaries,

which contain paraffin mixtures to reduce monomer evaporation and to improve overlamination

Molding and pressing compounds of unsaturated polyester resins usually contain, in addition to unsaturated polyesters and copolymerizable monomeric vinyl compounds with these, polymerization initiators and inhibitors as well as often powdered fillers and glass fibers or flatter glass fiber forms. Low-shrink, hardenable molding compounds also contain up to 30% by weight of thermoplastic polymers . In order to produce non-sticky products with optimal flow conditions under the necessary curing conditions, small amounts of finely divided alkaline earth oxide are mixed with the polyester molding compounds before mixing with the fillers. Thereby, a thickening takes place by salt formation with the carboxyl end groups in the unsaturated polyesters and a complex formation.

By adding the volatile, olefinically unsaturated monomers indispensable for the technical use, e.g. styrene, unintentional monomer loss occurs during the processing of unsaturated, hardenable polyester molding compounds in all processing techniques, for example by hand, fiber spraying - or the winding process, as soon as the unsaturated, hardenable molding compounds come into contact with the atmosphere. The monomer loss is not only undesirable for economic reasons, but the monomer concentration in the atmosphere also means a burden and danger for the worker at the workplace, so that the monomer concentration must be reduced with the help of usable technical devices such as e.g. suction devices, intensive aeration, etc.

From DE patent 948,816 it is known that the addition of waxy substances, for example paraffin, to unsaturated, curable polyester molding compounds not only reduces the evaporation of olefinically unsaturated monomers such as frex. styrene, but also reduces the polymerization-inhibiting effect of oxygen,

In DE-off.skrift 1.956.3 76 it is proposed to place a thin layer of a solution or dispersion of a waxy substance on a lacquer polyester resin just before curing, whereby the solvent for the barrier layer former, which is preferably sprayed on/ mentions petrol hydrocarbons and aromatic substances. Disadvantages of this method are that the barrier layer former must be dissolved in large quantities of solvent, usually 1% by weight solutions of the waxy substances are used, and the solutions must be applied to films of the unsaturated lacquer polyester resins in a separate work step. Care must also be taken that during the layer formation on the lacquer film with the solution containing the barrier layer, too high pressure, too high a temperature and too much solubility for the process components are avoided, as the curable lacquer film and the barrier layer can otherwise be mixed.

Only one layer of polyester resin is cured in one working step, such as e.g. in the case of varnishing, incidentally low styrene losses are achieved with paraffin additions. However, paraffins have the disadvantage that they also act as a separating agent. This means that the appearance of cured polyester resins in the presence of paraffins exhibits a cloudy, inert surface. If more unsaturated polyester resin is applied to such a surface and the resin is hardened, an insufficient connection is achieved, and both hardened hairpin layers can be separated relatively easily. The adhesion becomes worse the better the substrate is hardened.

The overlaminability of unsaturated polyester resins to waxy substances can be improved according to indications in German applications P 25 54 930.8 and P 27 05 966.1 by adding water-in-oil or oil-in-water emulsifiers with an HBL value of 1, 5 - 15, respectively by adding liquid alkanes or their mixtures. Disadvantages of both methods are that the adhesion between two laminate layers is still not completely satisfactory and that the polyester resins can only be produced with insufficient reproducibility.

It was the task of the present invention to develop unsaturated, hardenable polyester resins in which the olefinically unsaturated monomers do not or only to a lesser extent evaporate during processing, without the overlamination being affected.

It was surprisingly found that the addition of paraffin mixtures consisting of a paraffin with a melting point between 25 and 50°C and a paraffin with a melting point between 51 and 100°C to unsaturated polyester resins meets the above requirements.

The object of the present invention is thus low-evaporation, easily overlaminated, curable in the presence of common polymerization initiators, unsaturated polyester resins of

a) at least one ethylenically unsaturated copolymerizable polyester,

b) at least one ethylenically unsaturated, copolymerizable, monomeric compound,

c) a waxy substance as well as optionally

d) structural components and auxiliaries which usually find application in connection with unsaturated polyester resins, such as

are characterized in that they as waxy substances contain a paraffin mixture which essentially consists of at least one paraffin with a melting point between 25 and 50°C and at least one paraffin with a melting point between 51 and 100°C.

The polyester resins according to the invention surprisingly exhibit the advantage that the separating agent effect is canceled by the special composition of the paraffin mixture, without the monomer evaporation being enhanced.

The production of the low-evaporation, easily overlaminated, curable, unsaturated polyester resins according to the invention takes place in a manner known per se by mixing the paraffin mixture with the polyester resin components a) - d). It has proven appropriate to dissolve the paraffin mixture in an ethylenically unsaturated monomer, preferably styrene, and add the polyester resin to the resulting monomer solution.

The starting materials a) to d) which can be used for the production of low-evaporation, easily overlaminated, curable in the presence of common polymerization initiators, unsaturated polyester resins according to the invention are the following: a) Common condensation products of polyhydric, especially dihydric, carboxylic acids and their esterifiable derivatives are suitable as unsaturated polyester , especially their anhydrides, which are linked esterically with polyhydric, especially dihydric, alcohols, and possibly additionally contain residues of monovalent carboxylic acids and/or residues of monohydric alcohols and/or residues of hydroxycarboxylic acids, whereby at least part of the residues

must have ethylenically unsaturated, copolymerisable groups.

As polyhydric, especially dihydric, possibly unsaturated alcohols, common, especially acyclic groups, cyclic groups, as well as both species of these groups exhibiting alkane diols and oxalkane diols such as e.g. ethylene glycol, propylene glycol-1,2, propanediol-1,3, butylene glycol-1,3, butanediol-1,4, hexanediol-1,6, 2,2-dimethylpropanediol-1,3, diethylene glycol, triethylene glycol, polyethylene glycol, cyclohexanediol- 1,2, 2,2-bis-(p-hydroxycyclohexyl)-propane, 1,4-bismethylolcyclohexane, vinyl glycol, trimethylolpropane monoallyl ether or butenediol-1,4.

Furthermore, mono-, tri- or higher alcohols can be used in smaller quantities, such as e.g. ethylhexanol, fatty alcohols, benzyl alcohols, 1,2-di-(allyloxy)-propanol(-3), glycerol, pentaerythritol or trimethylolpropane. The polyhydric, especially dihydric alcohols are usually reacted in stoichiometric or nearly stoichiometric quantities with polybasic, especially dibasic, carboxylic acids or their condensable derivatives.

Suitable carboxylic acids or their derivatives are dibasic, olefinically unsaturated, preferably α;Æ-olefinically unsaturated carboxylic acids such as e.g. maleic acid, fumaric acid, itaconic acid, citraconic acid, methyleneglutaric acid and mesaconic acid respectively their esters or preferably their anhydrides. There may also be condensed in the polyester further other modifying-acting dibasic, unsaturated and/or saturated as well as aromatic carboxylic acids such as e.g. succinic acid, glutaric acid, cc-methylglutaric acid, adipic acid, sebacic acid, pimelic acid, phthalic anhydride,. o-phthalic acid, isophthalic acid, terephthalic acid, dihydrophthalic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, 3,6-endomethylene-1,2,3,6-tetrahydrophthalic acid, endomethylenetetrachlorophthalic acid or hexachloroendomethylenetetrahydrophthalic acid, also further mono-, tri- and higher basic carboxylic acids such as e.g. ethylhexanoic acid, fatty acids, methacrylic acid, propionic acid, benzoic acid, 1,2,4-benzene-tricarboxylic acid or 1,2,4,5-benzenetetracarboxylic acid.

The unsaturated polyesters are usually produced by melt condensation or condensation under azeotropic conditions from their constituents. For the method according to the invention, amorphous and possibly crystallizable unsaturated polyesters can be used.

It has usually proved appropriate that the unsaturated polyesters exhibit an acid number of from 10 to 100, preferably from 25 to 60, as well as an average molecular weight of approx. 600 to 4000, preferably 800 to 3000.

Regarding the composition of unsaturated polyesters, reference can be made, for example, to the book by H.V. Boenig, Unsaturated Polyesters: Structure and Properties, Amsterdam, 1964.

The molding compounds used in the method of the invention usually contain 10 to 70, preferably 15 to 50% by weight

calculated on the components a) to c) of unsaturated polyesters a). b) As copolymerizable, olefinically unsaturated, monomeric compounds, the vinyl and allyl compounds that are usually used for the production of unsaturated polyester resins are mentioned, such as e.g. styrene, substituted styrenes such as p-chlorostyrene or vinyltoluene, esters of acrylic acid and methacrylic acid and alcohols with 1 to 18 carbon atoms, such as e.g. methacrylic acid methyl ester, acrylic acid butyl ester, ethylhexyl acrylate, hydroxypropyl acrylate, dicyclopentadienyl acrylate, butanediol diacrylate and (meth)-acrylic acid amide, allyl esters, such as e.g. diallyl phthalate and vinyl esters, such as ethylhexanoic acid vinyl ester, vinyl pivalate and others.

Likewise, mixtures of the aforementioned olefinically unsaturated monomers are suitable. Preferably suitable as component b) are styrene, vinyltoluene, cc-methylstyrene and diallyl phthalate. Component b) is usually present in an amount of from 5 to 60, preferably from 10 to 45, % by weight in the polyester resin, calculated

on the mixture of the components a) + b).

c) As under point c) falling waxy substances which are usable for the paraffin mixture, according to the invention, mix at least

one paraffin with a melting point from 25 to 50°C, preferably from 46 to 48°C, and at least one paraffin with a melting point from 51 to 100°C, preferably 56 to 58°C.

Instead of the paraffins, however, other waxy substances can also be used, for example the paraffin oxidation products known as so-called montan wax, respectively their esters, karnau wax, long-chain fatty acids such as e.g. stearic acid, stearyl stearate, ceresin and the like.

To reduce the monomer evaporation and to form a non-adhesive surface as well as to achieve a good overlamination, the unsaturated polyester resins contain 0.01 to 5, preferably 0.05 to 1,% by weight, especially 0.1 to 0.5,% by weight of the paraffin mixture, calculated on the total weight of the components

a) and b) .

Particularly advantageous and therefore preferably used is

paraffin wax consisting of 0.01 to 0.5% by weight of a paraffin with a melting point of 25 to 50, preferably .46 to 48°C and 0.01 to 0.5% by weight of a paraffin with a melting point of 51 to 100, preferably 56 to 58°C, whereby the weight percentages are calculated on the total weight of the polyester resin components a) and

b).

d) As structural components and auxiliaries corresponding to point d), which can possibly be used in connection with unsaturated polyester resins, for example: thickeners, inhibitors, fillers, reinforcing agents as well as possibly inert solvents, polymerization accelerators, shrinkage-reducing additives and further auxiliaries which are usually used in processing of polyester resins.

As thickeners can be mentioned, for example: alkaline earth oxides or hydroxides such as calcium oxide, calcium hydroxide, magnesium hydroxide and preferably magnesium oxide as well as mixtures of these oxides and/or hydroxides. the alkaline earth oxides can also be partially replaced with zinc oxide. The content of thickeners in the polyester resins usually amounts to 0.5 to 5, preferably 1 to 3, % by weight calculated on the mixture of components a) and b).

As inhibitors, the usual ones come into play, such as e.g. hydroquinone, tert-butyl pyrocatechin, p-benzoquinone, chloranil, nitrobenzenes such as m-dinitrobenzene, thiodiphenylamine or salts of N-nitroso-N-cyclohexylhydroxylamine as well as mixtures thereof. The inhibitors usually occur in the polyester resins in an amount of 0.005 to 0.2, preferably 0.01 to 0.1% by weight calculated on the components a) and b).

Suitable fillers are e.g. ordinary finely powdered or granular inorganic or organic fillers such as e.g. chalk, kaolin, quartz flour, dolomite, tungspar, metal powder, cement, talc, diatomaceous earth, wood flour, wood shavings, pigments and the like.

As reinforcements come inorganic or organic fibers or flat, possibly woven forms thereof, e.g. such as glass, asbestos, cellulose and synthetic, organic

high polymers, such as polyesters or polyamides.

The fillers and reinforcements can be used in quantities

from 5 to 200% by weight calculated on components a) and b).

As possible additional substances that can be used are inert solvents such as e.g. ketones, esters and hydrocarbons in amounts of up to 100% by weight calculated on the components

a).

The unsaturated polyester resins according to the invention

can be pre-accelerated. Examples of polymerization accelerators include heavy metal salts such as cobalt and vanadium salts, tertiary aromatic amines, 1,3-diketone compounds such as acetylacetone, fi-ketoesters such as acetoacetic acid ethyl ester and 3-ketoamides, such as acetoacetic acid diethylamide and combinations of these compounds.

Shrinkage-reducing additives that may be used together are, for example, thermoplastic polymers such as polystyrene, styrene copolymers, polyvinyl acetates and/or poly(meth)acrylates. Preferably, thermoplastic polymers are used which contain carboxyl groups in amounts of from 1 to 5% by weight calculated on the total weight, bound in the molecular chain.

The shrinkage-preventing additives are usually used in amounts of from 1 to 30, preferably 8 to 15, weight % calculated on the weight of components a) and b).

According to the invention, paraffin mixtures are mixed into the structural components a) to d) in the low evaporation, easily overlaminated, hardenable polyester resins. Paraffin mixtures are those which contain paraffins whose melting point is above and below 50°C.

The mixing of the individual components a) to d) and the addition of the paraffin mixture can take place by using

ordinary mixing devices, for example with a stirrer or a roller. Unsaturated polyester resins produced in this way can be cured with polymerization initiators such as e.g. peroxides, azo compounds and others, optionally in the presence of polymerization accelerators

or co-accelerators respectively -promoters or by irradiation, for example with light, UV irradiation or accelerated electron beams-are possibly in the presence of light initiators and sensitisers.

The unsaturated polyester resins according to the invention are suitable for the production of coatings, thin layers and moldings without or with reinforcing materials as well as possibly fillers.

Their use is particularly advantageous for the production of molded parts by lamination, for example in hand processes or fiber injection processes, as well as wherever, when paraffin-free, unsaturated polyester resins are used, a particularly high concentration of volatile monomers occurs in the workplace or where the monomer emission is very high.

The parts and percentages stated in the examples are parts by weight and percentages by weight, respectively.

Unsaturated polyester resin:

Polyester resin A is a 66% styrene solution stabilized with 0.01% hydroquinone of an unsaturated polyester with an acid number of 50, which is prepared by melt condensation at 190 to 210°C in the presence of an inert gas atmosphere of maleic acid, o -phthalic acid and propylene glycol-1,2 in the molar ratio 1:2:3. The degree of isomerization maleic acid-fumaric acid was 95%.

Polyester resin B was prepared analogously to the instructions for polyester resin A, whereby, however, the starting components maleic acid, phthalic acid and propylene glycol-1,2 were condensed to produce the unsaturated polyester resin in the molar ratio 1 : 0.5 : 1.5. The degree of isomerization was 95%.

Polyester resin C was prepared analogously to the instructions for polyester resin A, but the starting components maleic acid, isophthalic acid and neopentyl glycol were condensed to produce the unsaturated polyester resin in the molar ratio 1:1:2. The degree of isomerization was 90%.

Polyester resin D was prepared analogously to the instructions for polyester resin A, but the starting ingredients maleic acid, tetrahydrophthalic acid, phthalic acid, diethylene glycol and propylene glycol were condensed to produce the unsaturated polyester resin in the molar ratio 1 : 0.5 : 0.5 : 1.0 : 1, 0. The degree of isomerization was 95%.

Polyester resin E was prepared analogously to the instructions for polyester resin A, but the starting components maleic acid, isophthalic acid, diethylene glycol and propylene glycol were condensed to produce the unsaturated polyester resin in the molar ratio 1:1:1:1. The degree of isomerization was 95%.

Measurement of the monomer evaporation:

In a flat bowl with a low edge (e.g. 25 x 25 x' 0.3 era) the polyester resin is distributed so that an even, 2 mm thick layer is formed. To determine the monomer evaporation, the weight loss is used

x o

within one hour at 23 + 1 C determined.

Overlamination test:

Test similar to practice:

A 3 mm thick fiberglass reinforced unsaturated polyester resin coating, consisting of 3 layers of fiberglass mat, is cured using 1% methyl ethyl ketone peroxide (50% in dimethyl phthalate) and 0.2 to 0.5% 1% cobalt octoate solution in styrene (1% cobalt content ) at a room temperature of 23 +• 1°C.

After exactly 24 hours, 1/3 of the upper laminate surface is uncovered with foil (starting point for a later tear test)

and a similar 3 mm thick glass fiber reinforced unsaturated polyester resin layer is overlaminated. After a further 24 hours, the upper laminate is torn from the lower one by hand.

Examples 1 to 8 and comparison examples a to f.

The polyester resins A and B were added to paraffins whose softening range was between 32 and 96°C.

The paraffins used and the added amounts in weight percent calculated on the polyester resin weight are summarized in the following tables.

As can be seen from the tables, comparison examples a, b, d and e show good adhesion between the layers, but large styrene evaporation and comparison examples c and f show weak styrene evaporation and poor adhesion between the layers.

Claims (3)

1. Low evaporation, good overlamination, curable in the presence of polymerization initiators, unsaturated polyester resins containing a) at least one ethylenically unsaturated copolymerizable polyester, b) at least one ethylenically unsaturated copolymerizable monomeric compound, c) waxy substances as well as possibly d) building components and auxiliary substances which usually find use with unsaturated polyester resins, characterized in that the polyester resins as waxy substances contain a paraffin mixture, which essentially be consists of at least one paraffin with a melting point between 2 5 and 50°C and at least one paraffin with a melting point between 51 and 100 C. <2. Polyester resin according to claim 1, characterized in that the polyester resin contains 0.01 to 5% by weight, preferably 0.1 to 1% by weight, calculated on the total weight of components a) and b) in the paraffin mixture. 3. Polyester resin according to claim 1, characterized in that the paraffin mixture consists of: a) 0.01 to 0.5% by weight of a paraffin with a melting point between 25 and r - O 50 C and b) 0.01 to 0.5% by weight of a paraffin with a melting point between 51 and 100°C, calculated on the total weight of components a) and b).