DE2223020A1 - Molding compound - Google Patents

Description

LM 2138

The Lobdell-Emery Manufacturing Company Alma, Michigan / USA

Molding compound

The invention relates to a molding compound with low shrinkage and high strength that is electrostatic or can be electrolytically coated if pressed without special preparation is made up of a polyester resin system with a thermosetting resin and a thermoplastic resin with the thermosetting resin is compatible, and an inert material for strength building.

Low shrinkage polyester molding compounds that may be reinforced with glass fibers have been used in industry Temporarily used in the manufacture of a wide variety of products. In the automotive industry, for example, are increasing

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Vehicle parts made from such masses with high strength. Most automobiles, however, are electrostatically sprayed with paint by the manufacturer for economic reasons and for reasons of convenience. Normally in electrostatic paint spraying, the paint particles sprayed by a spray gun have a negative charge due to the ionic content of a polar solution such as methyl & ethyl ketone in the dye, and a potential is given to the part "to be painted and grounded" so that the very small particles of dye adhere firmly to the part in a thin, but extremely dense, non-porous coating. In the case of parts coated by electrolytic precipitation, the parts to be coated are normally immersed in a trough containing the dye or the coating composition such as acrylic dyes that has been charged in order to achieve the desired coating by electrolytic precipitation an assembly line to the usual electrostatic paint spraying system or the usual system that forms a coating by electrostatic precipitation, difficulties arise when applying the paint or when coating such parts. Automobiles with such parts therefore had to be pre-exposed to the electrostatic paint spraying system and instead less advantageous paint spraying processes had to be carried out, i.e. processes that require far more paint and that do not form a satisfactory coating Get a coating that they are immersed in large dye troughs, which are suitable

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If they are made of non-conductive plastics, they are loaded in a manner that can be moved past the troughs and be sprayed with paint using conventional, non-electrostatic methods

Ub solve the problem that by using If non-conductive plastics arise, special precautions have been taken to protect the plastic surfaces for Prepare for the paint application · For example, xonen salt baths were used to finish the plastic surfaces Treat before applying paint, however, have to such baths are found to be expensive to use and do not result in a surface to which the paint adheres adheres · Even the use of conductive primers has not completely solved this problem. Bringing in of conductive materials in the plastic mass was due to the loss of compatibility of the components and / or the loss of structural strength of the molded part is unsuccessful.

The invention is therefore based on the object of creating an electrostatically sprayable mass that contains a network of soot aggregates that is uniformly dispersed throughout the mass in contact or separately at a distance of less than 100% , so that the pressed object has a sufficient Has conductivity in order to be able to be electrostatically sprayed with paint or provided with paint by electrolytic precipitation *

Furthermore, it is an object of the invention to provide a composition of the specified type and a method for producing the Create mass that has the physical properties

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of the resulting pressed part does not adversely affect, such as bending, tensile and compressive strength, a predetermined minimum hardness and a predetermined minimum Impact resistance required of the pressed parts.

The object on which the invention is based is achieved in that the resin system is compatible with Ruse, and that about 1 to 6 vol .- # carbon black is homogeneous in the mass are dispersed.

The invention is explained in more detail below on the basis of exemplary embodiments.

The invention relates primarily to high strength, low shrinkage plastic molding material that Can be electrostatically sprayed with paint or coated by electrolytic precipitation and that has a resin system a thermosetting polyester resin and a compatible thermoplastic resin, a filler and 1 to 6 vol .-? 6 contains soot. Other additives such as pigments, dyes, preservatives, catalysts, mold release agents and the like can be contained in the mass be.

According to the invention, it is essential that the resin system contains a thermosetting and a thermoplastic polyester resin, which react when heated in order to obtain the properties which are essential in the pressed parts. The resin system, which constitutes 20 to 60 i "of the total molding composition can contain about 12 to 42% thermosetting resin and 48 to 8% of thermoplastic resin, depending on the total weight of the resin system. However, to the

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To achieve the necessary conductivity, the mass must contain about 1 to 6% Ruse. The term "soot" is used in the present description for finely divided carbon which is produced by incomplete combustion or by the thermal decomposition of natural gas or liquid hydrocarbons. The main types according to the manufacturing process are chimney soot, furnace soot, thermal soot, acetylene black, and the like.Usually, the soot, which is an amorphous powder, has a specific gravity of about 1.8 to 2.1, a boiling point of ^ .20O ⁰ C and is insoluble in all solutions. For a full description of Russ, see "Condensed Chemical Dictionary" by Arthur and Elizabeth Rose, Reinhold Publishing Corporation, New York, NY, k. Edition, 196U, p. 218. Commercially available grades of carbon black are, for example, 320-mesh Vulcan ZC 72R from Cabot Corporation. If more than 6 volume carbon black is used, the physical properties of the molded parts are adversely affected, e.g. the high oil absorption of carbon black promotes porosity, reduces structural strength and causes the parts to drop below an acceptable level. However, the use of 6 % carbon black causes the desired conductivity to achieve a coating by electrolytic precipitation, for example by applying a direct voltage of 125 V at 1.5 A to a dye trough. It has been found that the masses containing carbon in a form other than soot are not acceptable. The molding compounds do not have the required structural strength and / or necessary conductivity when carbon in other forms is used in the compound.

2 0 9 B Λ 8/1 1 3 1

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Fillers which can be used herein are Calciuracarbonat, which is an inert filler, or aridere fillers, which are also suitable Ölabsorptionseigenscbaften bafoexn, wis hydrated alumina (Al ₂ 0, ^: 3 H ₂ O) or ASP 400 Clay "The Galciumcarbonatfüllstoff ICASM that is, a precipitated, uncoated variant of the filler ©, which is available under the product name "Camelwite" or ^K Sa * ptsi, so ^H dar Flr ^ ia Diamond Alkali Company or Harry Hollan & Sons. These fillers are only examples and can not be replaced by other generally known fillers.

The vertj ^ i'j.ii.c * .fce hifcz ^ h & rtemae polyester resin is some kind of Al Ignis *? - iii ^ Ve ^ khara «i« & ± n unsaturated polyester polymer used as a copolymer! satio.r »asit a monomer of the vinyl type in which L & .gp is. An example of this is a commercially available one sold by the Poppers Company

■ "" 37Oi Urs »in stK'ael't Wirkeiiä-ea Propylengiycolmaleina .-- i.hydrid eats si; .. eua Molvisrhaltais of lsi is, which is an acid? from ϋθ ·· 3ο lia.6. Other suitable polyester resins can be as ÄthylOE ^ i ^ r-oliealeate, which by reaction vox? V ^ laineä.ii.v'e ^ sit- Atbylsjnglycoi. are formed, or - · ΐ; ^ Sstörd-fs.llyj 7liihft.Ut-e, which are formed by the esterification reaction-Sidii between phthalic anhydride and allyl alcohol «Other polyester resins that have been proposed are that be? s in the "i Haas P- ^ O of the Rohn and Haajs Compar.y, Phll" delphia _t P ^^ a-tylveaia, USA "

It wux'de established ν dar * - there? thermoplastic resin used with low Sohrurgpitnig s;?, td "a Jiitsehärtbaren polyester resin in d & m sense V3rtxäg2 :; ii his muse »that it pigments and the. Ru0s .nicliv rejects · In experiments carried out ^{! Jr} ; j - 1e ffteif;. ^ - ':. FHt that incompatible

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7773020

Resins that reject the carbon cannot be used because they have no conductivity in the mass formed, and the sprayed or dipped object has a marbled or wavy surface, caused by the fact that less color is deposited on the non-conductive thermoplastic resin that rejects the soot than the thermosetting resin that does not reject the soot · A non-uniform surface is obviously unacceptable and if an incompatibility occurs the rejection rate is too high. Taking the above evaluation into account, the thermoplastic resins used, which react and chemically combine with the thermosetting resin, are the commonly used commercially available resins such as a styrene maleic anhydride resin having a molecular weight of about 80,000, -98 vol .- ^ Styrene, 2 96 times ine ai r-saafey & r & d, and 39 parts by weight of pesticides in solution. In the polyester resins, styrene can be replaced by chlorostyrene, vinyltoluenes, dichlorostyrene, diallyl phthalate and triallyley eesmate. Other commercially available M, thermosetting and thermoplastic resins can be used so long as they are compatible.

In addition to the important additives mentioned above, other materials can be used in the molding compound, such as a catalyst for curing the resin system, e.g., tertiary butyl perbenzonate, tertiary butyl peroctalate or the like. These Materials are available commercially, for example from Wallace & Tiernan Company. A mold release agent such as zinc stearate can be used to aid in the removal of the molded part from the mold. Suitable pigments and

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Dyes may optionally be used. However, these materials are usually not necessary as the molded article is being sprayed or coated. Finally, glass fibers can be incorporated to increase the structural strength of the pressed part. However, it is preferred to use staple glass silk which is hair thickness in diameter and about 6.3 to 63 in length. Suitable materials are commercially available from Owens-Corning Company and others. Additives such as a catalyst and mold release agent are negligible Contain quantities · The glass fibers can, however, be present in large quantities and normally a bulk molding compound has a higher percentage of glass fibers than a film molding compound. The glass fibers can constitute about 35 to 10 % by weight of the total molding compound.The determination of the amount depends on the ultimate strength desired and on the particular resin system used.If glass fibers are used, the other materials are determined in such a way that that results in 100 #.

A dough molding process is used to produce the polyester molding compound «the thermosetting and the thermoplastic harsa are optionally available with the The catalyst and deforarizing agent are mixed in a suitable mixer and the filler and carbon black are mixed mixed separately in a suitable mixer. Then the resin mixture is added to the mixture of filler and carbon black poured and the entire mixture is mixed further. Finally, if necessary, the glass fibers become the pasty substance added. When the glass is evenly dispersed in the resin, the material is ready to be transferred to the die · The

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Press mold operates at a temperature of around 80 to 160 ° C depending on the catalyst used. The thermoplastic resin causes rapid crosslinking and curing and very little shrinkage. Low shrinkage means less than about 0.005 mm per 12.7 mm if more than 6 ^ soot are used, does the resulting pressed product or just the film have too great a porosity and too many hollows than that it would be acceptable.

Two preferred examples of the invention will now be explained. In these the percentages are based on the volume unless otherwise stated.

example 1

16.8 ia Koppers Company Resin 3701 and 11.2% Koppers Company resin LPA-39, both resins as defined above, were mixed with 1.0 $ Tertiärbutylperbenzonat, based on the volume of resin, and 1.0 i "zinc stearate in a Banbury mixer mixed. 5 ^, 0 # calcium carbonate and 3 ^ carbon black were mixed separately and then the resin mixture was poured onto the mixture of the filler and the carbon black and the whole thing then mixed intensively. 15.0 $ staple glass floss about 6.3 to 19 aim in length and hair thickness was added to the mixture to provide an even dispersion The resulting Schütt pressasee is at bucket temperature Hitase hardenable from about 100 ° C in 30 minutes «

Example 2

A film compression molding machine with low shrinkage is as follows in accordance with the example 1 bit manufactured"

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Hitase-curing polyester resin of Example 1 Thermoplastic resin of example 1 tertiary butyl perbeiizonate (based on the

Marvolume)

Zincfl tears, t Calcium carbonate Rus3

Calcium hydroxide

Glass roving (12.7 to 50.8 mm)

16.8 J 11.2

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1.0 5 39.0 ?

3.0 ?

2.0 5 30.0 5

The resulting film molding compound is at one temperature from about 10 ° C in 10 minutes.

Typical physical properties of a conductive bulk test »« »Se and aiijsr conductive foil molding compound of the examples 1 and 2 are as follows;

Specific> «chesi weight (ASTM D792)

> 5? 0)

; iL £ ll-i IC! '5}

Barcol {N £ c

Pouring press 1.84 Foil Dimensions 0.2% molding compound 6.7 ft.lb/in* 2.02 6.2 ft.lb/in. 0.24 <£ f '-. 6 "\ kg / c" ² 22.5 ft.lb / in. * V3O _; 4 kg / cm ² ? i.5 ft.lb/in. - 52 kg / cffi! ² 2039 kg / cm ² 1125 kg / cm ² ^ 6 2109 kg / cm ² 114 60

2 C S S 4 S / · 1 S

The press releases of the examples are lightly coated by electrostatic spraying or by electrolytic precipitation. No special treatment of the plastic surface other than the usual wiping with a solvent is required and excellent paint adhesion and excellent surface results were obtained. The excellent physical properties mentioned above were obtained with a carbon black content of 3 ° . However, good results have been obtained using 1 to 6 carbon black in the approaches, both in terms of good coating and structural strength.

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Claims (1)

Expectations 1. molding compound with low shrinkage and high strength, which can be electrostatically or electrolytically provided with a coating if it is pressed without special preparation, consisting of a polyester resin system with a thermosetting resin and a thermoplastic resin which is compatible with the thermosetting resin is, and an inert material for strength formation, characterized in that the resin system with carbon black is compatible, and that about 1 to 6% by volume of carbon black is homogeneously dispersed in the mass 2. Composition according to claim 1, characterized in that the thermosetting resin is propylene glycol maleic anhydride 3 «Composition according to claim 2, characterized in that the thermosetting resin is styrene maleic anhydride with a molecular weight of 80,000. . . ,, k. Composition according to claim 3ι characterized in that it contains grass fiber 5. Composition according to claim 4, characterized in that the thermoplastic resin consists of 9Θ vol .- # styrene and 2% Maleic anhydride consists of 6. Mass according to claim 1, characterized in that the resin system comprises 20 to 60 vol. £ of the total mass. 209848/1191 7. Composition according to claim 6, characterized in that the thermosetting resin and the thermoplastic resin comprise approximately 12 to kZ i » or k8 to 8 £ of the entire resin system * 8. Electrically conductive press article, consisting of the A molding compound according to claim 1. 9 Process for the production of plastic molding material, which can be coated electrostatically or electrolytically, characterized in that a polyester resin molding compound is formed that about 1 to 6 vol .- ^ soot are dispersed therein, and that the mass is pressed into the desired shape. 209848/1191