DE2234307A1 - GRAVILABLE, LOW VARIETY HARDENING, UNSATURATED POLYESTER MOLDING COMPOUNDS - Google Patents

Description

Bayer Aktiengesellschaft 223 A Leverkusen, Bayerwerk Central area Patents, trademarks and licenses

July 11, 1972

Free-flowing, low-shrinkage curing, unsaturated polyester molding compounds

Object of the present invention are free-flowing, low shrinkage to form moldings _v curable unsaturated polyester molding compositions which can be obtained without the use of known thickening agent or metal oxide -hydroxidbasis.

From the German Auslegeschrift A 4446 39c 16 a process for the production of crystalline unsaturated polyesters is known, according to which fumaric acid with a glycol of the general formula: HO (CH ₂ ) _x OH, where χ is 2 to 18, or a symmetrical dialkyl derivative thereof , the alkyl substituents being on the same carbon atom, reacting with one another at an elevated temperature until a product with an acid number less than 100 is obtained.

The unsaturated polyester obtained in this way, when mixed with styrene, form a crystalline, polymerizable mixture and are therefore suitable for the production of free-flowing ones Polyester molding compounds without the need for further auxiliaries.

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OSfGlNAL INSPECTED

From numerous other publications (German OffenlegungsSchriften 1 694 857, 1 953 062, 2 051 663, 2 061 585) processes are known for curing mixtures of unsaturated polyesters and styrene with low shrinkage, however thermoplastic substances are added to these mixtures before curing.

As was to be expected, the addition of thermoplastic compounds to the unsaturated polyester molding compounds Patent A 4446 39c 16 in almost all cases that the crystallization is disturbed sensitively. Instead of the without Tacky-free crystalline mixtures that can be produced by thermoplastics result in sticky resins which are used for the production of free-flowing polyester molding compounds in the sense of the task at hand are unsuitable.

It has now surprisingly been found that cellulose esters of organic acids occupy an exceptional position here. It is possible with their help, not only unsaturated ones Polyester-styrene mixtures within the meaning of patent application A 4446 39c 16 with the usual styrene contents of about 20 - 40 # to be processed into pourable molding compounds, which can be hardened with low shrinkage; Furthermore much more styrene can be added to such mixtures without adversely affecting the crystallinity will.

The invention therefore relates to free-flowing, low-shrinkage polymerizing compositions based on ethylenically unsaturated polyester, polymerizable monomers and thermoplastic compounds, which are characterized by the following composition:

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a) 30-70 parts by weight of an unsaturated crystalline polyester which contains fumaric acid residues and residues of glycols of the general formula HO-CH ₂ -H-CH ₂ -OH, where R is an alkylene of the formula (GH ₂ ) with ζ = 1-18, or 'symmetrical dialkyl derivatives of these alkylene radicals, the alkyl substituents being on the same carbon atom, or denote cycloalkylene radicals.

b) 20-75 parts by weight of styrene.

c) 1-30 parts by weight of cellulose esters of organic acids. The sum of a, b and c is equal to ¹ 100 each.

The unsaturated polyesters of the invention are described in detail in German Patent A 4446 39c 16. For the purpose of of the invention it is not strictly necessary for manufacture of the unsaturated polyester to use fumaric acid as the starting substance. This can also be done by rearrangement Maleic acid during the. Production of the unsaturated polyester are formed. Particularly preferred diols in the sense of the invention are neopentyl glycol, dimethylolcyclohexane-l ^ and 1,6-hexanediol.

Examples of the unsaturated polyesters of the invention are the polycondensation products from: neopentyl glycol and Fumaric acid, dimethylolcyclohexane-l ^ and fumaric acid, butanediol-1,4 and fumaric acid, 1,6-hexanediol and fumaric acid.

The polyesters can be used alone or in combination with one another be used.

The esterification products of cellulose with organic acids such as acetic acid, Propionic acid, butyric acid used. Examples are: cellulose acetate, cellulose acetate propionate, cellulose acetate

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butyrate. These thermoplastic polymers are commercially available from Farbenfabriken Bayer AG under the trademark Cellit available.

The curing of the resin mixture according to the invention takes place with the known initiators, such as peroxides, such as benzoyl peroxide, tert-butyl perbenzoate, cyclohexanone peroxide under heat and Pressure.

The free-flowing, low-shrinkage polymerizing masses of the invention can in a known manner with further additives, such as molding agents and lubricants, glass fibers, stabilizers, pigments, fillers are added. Instead of The glass fibers can be wholly or partly synthetic fibers or natural, organic fibers such as jute, sisal, cotton or mineral fibers such as asbestos can be used.

The free-flowing, low-shrinkage polymerizing masses ^ of the invention can preferably be employed and used where great dimensional stability is desired, such as e.g. in car body construction, in the furniture industry, in the manufacture of shells and other molded parts.

The following examples explain the invention:

Example 1;

Production of the unsaturated crystalline polyester (according to German Auslegeschrift A 4446 39 c 16).

1.000 mol of fumaric acid and 0.982 mole Ne'opentylglykol are condensed in the presence of 0.037 g Toluylenhydrochinon within 24 hours at 190 ⁰ C with elimination of water up to an acid number of 40th

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30SPSF / 1 IPR

The polyester is then still with 0.019 g of toluene hydroquinone and 0.016 g of chloranil are added.

At 10O ⁰ C, the polyester is then reacted with 54.3 g of a cellulose acetate propionate, whose Estergruppen consist of approximately 10 # from acetate and propionate to about 90% and 216 g of styrene were added under stirring. The polyester mass crystallizes on cooling. It is ground and results in a free-flowing, dry powder that does not cake even when stored for a long time.

Example 2 (comparative example)

The procedure is as in Example 1; however, instead of the Cellulose ester (Cellit PR 900, manufacturer Bayer AG) according to the example 1, 54.5 g of polymethacrylate (Plexigum H 7, manufacturer Röhm, Wiesbaden) were used.

On cooling, a sticky, doughy polyester mass is obtained, that cannot be ground.

Example 3

Production of pourable molding compounds:

In a kneader, 1000 g polyester composition is melted according to Example 1 at a Knetertemperatür of 80 ⁰ C. 20 g of 3-bis (tert-butylperoxiisopropyl) benzene are added; after 5 minutes, 40 g of zinc stearate and 100 g of chalk (Durcal 5; manufactured by Omya GmbH, Cologne) and after minutes 300 g of glass fibers (13 mm long) are kneaded in. All work is carried out in a closed kneader in order to avoid styrene losses.

The pasty to doughy mass at 80 ⁰ C is crushed in a hammer mill after cooling to room temperature.

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smaller, so that a grist of 1 - 5 was now a thick grain. The compositions are processed by hot-pressing at 140 16O ⁰ G to pressings. These pressed parts had the following properties:

Shrinkage according to DIN 53464: 0.2 #

Flexural strength, standard rod, DIN 53452: 600 (kp / cm ² )

Impact strength, standard rod, DIN 53453: 7 (cmkp / cm ² )

Martens grade, standard rod, DIN 53458: 180 ( ⁰ C)

Surface markings due to different shrinkage at points of different wall thicknesses were not observed.

Example 4 (comparative example)

The procedure is as in Examples 1 and 3; however, the molding compound did not contain any cellulose acetate propionate (Cellit PR 900).

All other components are used in the same amount. The molded parts made with these masses have following properties:

Shrinkage according to DIN 53464: 0.6 # ■

Flexural strength, standard rod, DIN 53452: 400 (kp / cm ² )

Impact strength, standard rod, DIN 53453: 7 (cmkp / cm ²

Martens degree, standard rod, DIN 53458: 180 °

Strong surface markings were made in places of different wall thicknesses observed.

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Claims (1)

Claims; . Free-flowing, non-shrink polymerizing compounds based on Ethylenically unsaturated polyester, polymerizable monomer and thermoplastic compounds, thereby marked that they are out a) 30-70 parts by weight of an unsaturated crystalline polyester which contains fumaric acid residues and residues of glycols of the general formula HO-CH ₂ -R-CH ₂ -OH, where R is an alkylene of the formula (CH ₂ ) "with ζ = 1 - 18, or symmetrical dialkyl derivatives of these alkylene radicals, where the alkyl .substituenten are on the same carbon atom, or are cycloalkylene radicals, b) 20-75 parts by weight of styrene and c) There are 1-30 parts by weight of cellulose esters of organic acids, the amounts of a, b and c being chosen so that their sum is equal to 100. Le A 14 513 - 7 - 309885/119