DD200136B1 - HEAT-CURABLE UP MOLDING WITH IMPROVED STORAGE CAPABILITY - Google Patents

Description

Field of application of the invention

The invention relates to molding compositions of unsaturated polyester resins, fibrous reinforcing materials and powdered fillers, additives to reduce shrinkage, curing initiators, inhibitors, lubricants, thickening agents and other additives. The production of the UP molding compounds takes place in putty-like and planar form and differs significantly in the choice of the impregnation process for the fibrous reinforcing material. UP-molding compounds are processed by compression molding, injection molding and injection molding into moldings which have high strength and excellent electrical properties. They are deshallb primarily used in the electrical industry.

Characteristic of the known technical solutions

The crosslinking of UP molding compositions is usually carried out with the aid of organic peroxides as curing initiators, which are added to the UP molding compositions already in the production. Under the influence of heat, the peroxide decomposes into free radicals and thus initiates the polymerization. Although a sufficient crosslinking reaction takes place only in the range of processing temperatures between 120 ⁶ C in 150 ⁰ C, a slow decomposition of the peroxide takes place even at room temperature of 2O-30 ° C. In the case of UP molding compounds, this peroxide decomposition is still supported by the metal ions contained in fillers and pigments. The initiated by the peroxide decomposition polymerization leads to gelling of the resin, to a change in its reactivity and thus to a permanent deterioration of the processing properties during storage. Unsaturated polyester resins for molding compositions are commonly used as a solution in styrene. Due to its vapor pressure, the styrene tends to evaporate during storage of the molding compound, especially in the summer months at higher storage temperatures. This leads to drying out of the molding compound, to a deterioration of the flow properties and curing. The packaging in impermeable material is extremely expensive. Styrenverdunstung also leads to a significant environmental pollution.

It is already known to add unsaturated polyester resins to prevent the formation of radicals phenolic inhibitors. However, when used at an effective concentration, these not only prolong the gelling time at room temperature, but also the cure time during processing itself.

In AS 1098712 the storage stability of peroxide-free polyester resin compositions is improved by adding phosphorous acid and / or phosphorous acid ester in dissolved form to the polyester resin compositions. By this method, the pure unsaturated polyester resin is stabilized. The polyester resins do not yet contain peroxides as a curing catalyst and no fillers with the metal ions favoring the Radikaibildung. Pure unsaturated polyester resins are usually stored in well closable barrels or tanks so as to avoid unwanted styrene evaporation.

According to the OS 2246819 molding compositions are thereby stabilized against premature classification that a mixture of a phenolic inhibitor such. As hydroquinone or p-quinone and hexamethylphosphoric triamide is used. Although this improves the shelf life of the UP-molding compositions while maintaining low processing times, the method has the disadvantage that a tight-fitting, impermeable for the used vinyl monomer packaging must be selected in order to avoid deterioration of the processing properties. The hexamethylphosphoric triamide used as a costabilizer is also a carcinogenic compound whose use in production involves considerable risks.

It is also already known to produce low-evaporation unsaturated polyester resins curable in the presence of polymerization initiators. After OS 2738805 the Monomerverdunstung is prevented by addition of a paraffin mixture consisting essentially of at least one paraffin having a melting point between 25 ⁰ C and 50 ° C and at least one paraffin having a melting point between 51 ° C and 100 "C. The addition Although the paraffins lead to a lessening of laminar styrene losses in the case of laminating resins, they have the disadvantage that they act as release agents, which considerably complicates the paintability of moldings with paraffin addition molding compounds Storage is not prevented.

Object of the invention

It is an object of the invention to produce UP molding compositions with improved shelf life, which have consistent processing properties over a longer period of time, especially at higher storage temperatures in the summer months. The UP molding compositions are to be produced with improved shelf life using readily available, non-toxic domestic raw materials.

Explanation of the essence of the invention

The invention has for its object to avoid the onset during storage at room temperature formation of free radicals and to reduce the Styrenverdunstung in the molding materials to a minimum.

The object of the invention is achieved in that the joint use of phenolic inhibitors, esters of phosphorous acid and long-chain carboxylic acids leads to a particularly effective elimination of free radicals during storage, as well as the Styrenverdunstung prevented or reduced to a minimum.

The phenolic inhibitors of the invention include dihydroxybenzenes and their alkyl derivatives. They are in

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Amounts of 0.01 to 1.0Gsw .-%, preferably from 0.03 to 0.2 wt .-%, used. The phenolic inhibitor solution used in acetone or alcohol. Hydroquinone is preferably used. The esters of phosphorous acid according to the invention comprise a) tertiary phosphorous acid esters of the formula

/ 0-21 P ^ 0 - H2

where R 1, R 2, R 3 may be identical or different alkyl, alkenyl, aryl or aralkyl radicals,

b) cyclic phosphorous acid esters of the formula

/ 0 - CH CH ₂ - 0

RO - P C ^ N. он

^ O - CH ₂ ^ OH ₂ - (Г

where R = aralkyl radicals,

c) neutral esters of phosphorous acid of the formet

where R 1, R 2 may be the same or different alkyl, alkenyl, aryl or aralkyl radicals. The tertiary phosphorous acid esters are used with priority, more preferably from this group Arslkylphosphite, z. Trie (nonylphenyl) phosphite.

The phosphorous acid esters according to the invention are used in amounts of from 0.1 to 5.0% by weight, preferably from 0.3 to 2.0% by weight, based on the unsaturated polyester resin. They are either dissolved directly in the unsaturated polyester resin or mixed in solution with the unsaturated polyester resin. A preferred embodiment is the use of a solution of both stabilizers in acetone or alcohol.

As long-chain carboxylic acid to prevent Styrofverdunstung be saturated or unsaturated fatty acids having predominantly 16-18 carbon atoms or mixtures of these saturated and unsaturated fatty acids used. Since the long-chain fatty acids simultaneously have an excellent lubricating effect, they can be used instead of other lubricants or in admixture with other lubricants.

The amount used to achieve the advantages of the invention, based on the unsaturated polyester resin, 3.0-15.0, preferably 5.0-9.0 G ew .-%.

The other components of the U P molding compositions, such as unsaturated polyester resins, the a π polymerizable η monomers, hardening initiators, fillers. Reinforcing materials, thickening agents. Lubricants, additives to reduce shrinkage are known.

The polyester resin molding compositions of the invention are prepared by known methods. The preparation of flat molding compounds by mixing the unsaturated polyester resin, optionally additives to reduce the shrinkage and the curing initiators, stabilizers, monomers, fillers, lubricants in an intensive mixer. After the thickening agent has been added, the impregnation of a glass fiber mat takes place. The production of shapeless molding compounds takes place in sigma blade kneaders or in tendons 11 kneading.

While retaining the previous characteristics of the UP molding compositions, molding compositions according to the invention have the additional advantage that \. does not diminish the realness of the molding compound,

2. the storage time of the molding material is sufficiently long even at temperatures up to 30 ⁹ C.

3. the processability is constant over the guaranteed storage period, and

4. cheap, non-toxic raw materials can be used and can be dispensed with a complex packaging. Auführungsbelspiele

To enforce the experiments, a commercial polyester resin, having an acid number of about 28 and a styrene content of about 35% is used. The polyester resin is stabilized against premature gelation. example 1

To test the storage stability, 100 parts by weight of the polyester resin were mixed with 2 parts by weight of tertiary butyl perbenzoate and the inhibitors indicated in Table I were added. The inhibitors were dissolved in acetone. These samples were stored at 70 ^° C. in the drying cabinet and the time until the start of the classification was determined. The reactivity of the samples was determined by determining the temperature increase at 120 * C. In Table I is indicated the time of temperature rise of 90-120 ⁰ C.

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Table I phosphite Outline at Increase in temperature hydroquinone TNPP 70 ⁰ C (h) 120 "Ct 90-120 (sec parts by weight (Gewicntstl.) _ 2 85 _ 4 86 0.01 - 9 128 0.02 40 168 12:05

0.1 - 80 316

0.05 0.1 60 87

0.05 0.3 72 98

0.05 1.0 72 122

A noticeable improvement in the Ugerfähigkeit is achieved with hydroquinone alone from 0.05Gew .-% but this is associated with a significant extension of the reaction time. Combinations according to the invention have longer gelation times and shorter reaction lines.

Example 2

To test the Styrenvetdunstung samples of 100 parts by weight of polyester resin and 7 parts by weight of stearic acid were mixed, placed in a Petri dish and determined the styrene evaporation as a function of time. For comparison, the polyester resin was tested without addition and with zinc stearate,

Table II

Styrenverfust [д / т ^г | at 30 * C

Time (h) without added stearic acid 19.5 Lagerfahigkeii (weeks) zinc stearate 0.5 359 26.0 PE sacks PA sacks 26.0 1.0 455 28.5 43.0 1.5 465 30.0 68.0 2.0 480 31.0 82.0 3,0485 35.5 107.0 4.0 490 128.5 Example 3 became a putty-shaped polyester resin In a sigma-blade crater ν 1 000 parts by weight mass produced according to the following recipe: UP Нзгг 20 parts by weight Sutvic perbenzoate 2.5 parts by weight hydroquinone 20 parts by weight Phosphite TNPP 38 parts by weight stearic acid 2 390 parts by weight calcium carbonate 350 parts by weight styrene 100 parts by weight polystyrene 1100 parts by weight Glass fiber stack 6 mm ί PE sacks / metal drums as well ii The molding material was both и chosen: η polyamide film welded and stored at 30 ° C. When Measure of the Lagerfahigkeii • Ball pressure hardness   processing properties

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The storage result emphasizes the advantages of the invention. While in styrene-tight film and molding compounds ear stearic acid are stored longer, no stearic acid and without phosphite in this package is not sufficient stability to achieve.

From the molding compound, test specimens and molded parts without demolding difficulties were produced using the usual parameters of the vulcanization. The moldings showed smooth surfaces, no deposit formation.

Illл Table ill, the passwords are recorded:

Impact bending strength k./m ^? 18.7

Flexural strength IMPa) 82

Shrinkage ° 'o 0.16

Water consumption mg 10

Ball Pressure Hard MPa 215

Dielectric strength KV / mm 11.2

Claims (4)

-1- 232 293 5 Invention claim: 1. Thermosetting UP molding compositions with improved shelf life, characterized in that based on the unsaturated polyester resin 0.015-1% by weight of phenolic inhibitors and 0.4 -5% by weight of phosphorous esters Acid and 3 * -15% by weight of 4-chain carboxylic acids are added. 2. UP-Formmasseafiach point 1, characterized in that are used as phenolic inhibitors dihydroxybenzenes and / or their alkyl derivatives. 3. UP molding compositions according to item 1, characterized in that are used as esters of phosphorous acid tris (nonylphenyl) phosphite and / or cyclischeePentaerythritmiscripbosphit and / or neutral phenyl ester of phosphorous acid. 4. UP molding compositions according to item 1, characterized in that is used as the long-chain carboxylic acid stearic acid.