DE2404658C3 - Process for the continuous extrusion molding of a mixture of a thermosetting and a thermoplastic material - Google Patents

Description

The invention relates to a method for the continuous extrusion of a mixture of one thermosetting plastic, a thermoplastic plastic, fillers and a catalyst in which the mixture in a screw press below the curing temperature of the thermosetting plastic plasticized and compacted is passed through an extrusion mold, in which the mixture with hardening of the thermosetting plastic is heated.

The extrusion of thermoplastics, such as. B. polystyrene, polyethylene and vinyl chloride resins, has heretofore been widely practiced in various fields. However, the usage is of molded articles made of thermoplastic resins because they are limited in heat resistance and mechanical strength are inferior to thermosetting resins.

DE-PS 1187 789 discloses a method for extruding special thermosetting plastics known, heated in the molding compounds in the mouthpiece of the extruder to almost the curing temperature and the feed speed of the strand is regulated so that from the mouthpiece a dimensionally stable, but not yet fully hardened strand emerges. The plastic used, namely High molecular weight polyethylene is a thermoplastic, due to the addition of thermal black and Peroxide catalyst, however, it is made crosslinkable and hardenable. This known method has However, it has various disadvantages: Because of the low reactivity of the mass, a long curing form is required needed. The long curing form in turn requires a release agent or a mold release agent, what a very complicated device must be used. Furthermore, because of the long curing mold a high extrusion pressure is needed. When a high extrusion pressure is used, it is However, it is difficult to obtain a homogeneously cured molded part, since a local one due to the friction Temperature increase and / or a reaction can take place in the extruder.

DE-OS 17 69 950 describes a process for continuous extrusion of the aforementioned Genus. However, in this known method, the thermoplastic is in the form of synthetic fiber material before and serves to reinforce the thermosetting plastic. He therefore goes with extrusion does not melt into the molten state, but retains its fiber form. The known procedure has numerous disadvantages: In general, unsaturated polyester has a high degree of shrinkage during hardening, as a result of which the molded products produced develop cracks. Hence the addition of Reinforcement material in the form of fibers is crucial to prevent the occurrence of cracks.

Unsaturated polyester has a low molecular weight before curing and therefore is The viscosity of the mass with the unsaturated polyester in the melt is extremely low. Because of this low Viscosity there is occasionally a separation of polymer and fiber in the mold. Hence it is very difficult to obtain molded articles in this way.

The invention is therefore based on the object in a method of the type mentioned at the outset Use of unsaturated polyester to obtain flawless products in a process that is a allows easy control and maintenance of the deformation process.

The object is achieved according to the invention in a method of the type mentioned at the outset solved that a mixture of 99 to 30 parts by weight of a mixture of an unsaturated polyester and a copolymerizable unsaturated one. Monomers in a weight ratio of 80:20 to 30:70 as thermosetting plastic and 1 to 70 parts by weight of the thermoplastic plastic is used, wherein the thermoplastic is in powder form and is melted.

The inventive method moldings are obtained which have no cracks, pores or Have distortions and therefore have a good surface, since the shrinkage of the unsaturated Polyester when curing by adding the thermoplastic, z. B. polyvinyl chloride, can be reduced. In the method according to the invention, a laminar flow can also be achieved, since the lowering of the Viscosity of the unsaturated polyester in the melt due to the addition of the molten thermoplastic high molecular weight can be prevented; while the viscosity is in a suitable Area held.

It is also possible to extrude the plastics under relatively low pressure. Because of the short Curing form can also combine the device

be panned.

According to a preferred embodiment, a polyvinyl chloride powder is used as the thermoplastic material used with a particle size of up to 100 μm

Preferably, the mixture is plasticized in α he screw press so that it exits the Screw press has a flowability that has a needle penetration number of at least 20 under a load of 100 g for a loading time of 5 s according to ASTM D 5

According to a further preferred embodiment, the heating in the extrusion die at a temperature between 80 and 25O ⁰ C, the mold wall at a pressure up to 200 kp / cm ² and carried out a residence time of between 1 second and 5 minutes.

To better illustrate the invention, the drawing is described below. In the drawing shows

F i g. 1 is a flow sheet illustrating continuous extrusion molding;

F i g. 2 shows a sectional view of an extruder used to carry out the method;

F i g. 3, 4 and 5 sections of modifications of the extrusion press according to FIG. 2 where the extreme end is varied,

F i g. 6 is a graph illustrating the flow properties of a thermosetting phenolic resin, namely the relationship between needle penetration value and temperature, and

F i g. 7 is a graph showing the flow properties of a thermosetting unsaturated polyester resin compound illustrates the relationship between needle penetration value and temperature.

The method according to the invention will first be described with reference to FIG. 1 illustrates.

In the kneading step, a raw material which is a thermosetting resin, a hardening agent, is a Filler and other additives, mixed or melt kneaded to form a homogeneous mass. About the flow properties of the plastic during extrusion and the quality of the resulting In order to improve the molded article, it is desirable that the mixing and kneading in the kneading step is sufficient perform.

Some thermosetting plastics are allowed to undergo the curing reaction even at room temperature expire, and most thermosetting plastics are only moderate in their heat resistance, and the The processing temperature range is extremely limited. Consequently, the pot life of the plastic is or the temperature setting in the kneading stage is very important.

The mixing of the components of the starting mixture can be carried out by numerous methods will. The appropriate method is selected depending on the type of plastics. For example all components can be mixed at the same time or added one after the other. It is also possible that Components of the starting material in advance Before mixing some mixtures and finally adding them to mix together a mixture.

The above knot can be made using a high speed disperser, ^ a kneading roller, a hot roller, a kneader, a compression kneader, a Bunburymixer, a Henschel mixer, an extruder of the screw type or the like.

In the event that a screw-type extruder is used in the kneading stage, it becomes possible to use the Carry out kneading and extrusion stage one after the other in a continuous manner. In addition, the use of a screw-like extruder for kneading is advantageous in that, as the output components are kneaded in a closed chamber, splashing or leakage of raw material is effective can be prevented. It is of course possible to carry out the kneading and extrusion stages separately, ίο but if the raw material has a short pot life is it is preferable to carry out kneading and extruding in a continuous manner.

If the kneading and extrusion steps are carried out separately, the kneaded raw material is in liquid, granular or powdery state or in the form of a ribbon (e.g. with a thickness of 2 up to 3 mm) or a strand and then fed to the extrusion stage

In the extrusion step, that coming from the kneading step under atmospheric or elevated pressure Raw material transported through an extruder. The speed of rotation of the screw can be varied freely will. Here, the plastic is due to the heating effect of the cylinder of the extruder and the The frictional heat of the plastic itself is softened and conveyed to the extreme end of the extruder.

The plastic mixture is then extruded through a preform and curing mold where the Deformation is completed and the extruded material is hardened during transport. To that of the Deformation stage to be supplied mixture in the uncured or pre-cured, d. H. not yet complete To maintain the hardened state, it is necessary to have a heating or cooling zone in the extruder to control the To provide cooling or heating and for softening with high power.

When carrying out the hardening step, a heating or cooling zone is provided in the hardening mold, as required, in order to carry out the deformation while adjusting the temperature. For example, the entry temperature of the curing mold is kept low while the exit temperature is kept high. It is also possible to keep the entire curing mold at a constant temperature or to cool the entrance of the mold. The deformation takes place at an average temperature in the mold in the range from 80 to 250 ^° C., but this does not preclude part of the mold from being cooled.

The hardened molded article is heated for post-hardening or cooled to cause warping correct and cut to the desired dimensions to obtain a final product.

The exact procedure is now based on the in FIGS. 2 to 5 shown devices described in more detail.

A raw material 20 containing thermosetting plastic, filler, hardening agent and other additives is fed to a hopper 2 of an extruder. The raw material becomes little by little and continuous by rotating an extrusion screw 3 installed in a cylinder 1 with kneading to the extreme End part (in Fig. 2 to the right) extruded. At this point the raw material is due to the friction of the plastic molecules or heated by friction between the plastic component and the screw. Hence here becomes a Coolant passed through coolant lines 4, 5, 6 and 7 to accelerate the increase in temperature and to control the progress of the hardening reaction.

In the case of some raw materials, these lines can be heated by passing a heating medium through them will.

The extruded material is then fed into a preform 11 which is attached to the extreme end portion of the extruder by means of a fastening bolt 13. The hardening reaction has not yet been triggered here. At this point, the temperature of the plastic is controlled by passing a heating medium through a heating line 12, so that the resin has a viscosity corresponding to a needle penetration number of at least 20, preferably at least 200 (this value is under a load of 100 g for a loading time of 5 seconds according to the test specified in ASTM D 5 for the penetration of bituminous substances). If the needle penetration value is luciiici äia jiu, uci riicuwiuciMciiiu In uci νυΠυιιΐΐέϋ is high.

The softened material extruded from the preform 11 is immediately placed in a curing mold 14 and 15 heated with heating lines 18 and 19, whereby the plastic is completely hardened and a product 21 is obtained. In general, the extrusion process takes place with a rigid, stationary curing mold 14 and 15, but under certain conditions it is desirable that the curing mold be moved. Around To achieve this feature, oil pressure cylinders 16, 17 and 22, 23 are provided. In such a case it will be Cylinders 22 and 23 for moving the slide molds 14 and 15 back and forth in the extrusion direction and Cylinders 16 and 17 used to move the mold halves perpendicular to the extrusion direction.

In the in F i g. 3 apparatus shown, the kneaded, thermosetting compositions between a A pair of heated conveyor belts 31 and 32 are extruded, which revolve from the extreme end of a cylinder 30. When this device is used as a curing mold, a plate-like object 33 can be continuous getting produced.

A device as shown in FIG. 4 is shown to carry out the Procedure are used. A tubular, softened material attached to an opening 42 of a Extruder 41 was preliminarily formed, is encompassed by a raised curing mold 43. Then a Plug 46 attached to the end portion of tube 44 and compressed air 45 blown into the interior of tube 44, so that it comes into close contact with the surface of the curing mold 43.

Furthermore, an apparatus as shown in FIG. 5 can be used. Will this apparatus is used, at an opening 52 of an extruder 5t vorgeforir.ies raw material is passed through a curing mold 53, which is equipped with a pressure-lowering chamber 55 and an air-permeable hole 56 is provided. The material is extruded as it passes through Lowering the pressure of the curing mold 53 is brought into close contact.

In the continuous extrusion process, both the flow properties and the hardening properties are important of the molding material are very important factors. Therefore, the physical and chemical properties of thermosetting plastics.

In general, thermosetting plastics have flow properties as shown in FIGS. In particular, when heated, a thermosetting resin is softened from around the point a, and its needle penetration number increases abruptly. However, if the temperature is further increased and approaches the vicinity of the point b, the needle penetration number decreases due to the curing reaction, and the plastic is completely cured and does not develop flowability even with the application of pressure (point C).

It is therefore necessary to give the plastic optimal flow properties by adjusting the heating temperatures of the extruder and the opening can be set within such a range in which a Curing reaction is not triggered. Furthermore, the flow properties of the plastic, i. h., that Degree of needle penetration, appropriately by adjusting the mixing ratio of the components of the molding material, e.g. B. a mixing ratio between the thermosetting plastic and the filler.

The curing properties of a thermosetting plastic vary depending on the type of Catalyst, the hardening agent and hardening promoter, the mixing ratios of these agents, the Temperature of the mold or the like, the residence time and other factors.

Flow properties of a common phenolic resin are shown in FIG. 6, and FIG. 7 is a diagram that is the flow properties of an unsaturated polyester compound, as shown in the following example! is illustrated shows.

The term "unsaturated polyester resin" as used here includes condensation products an unsaturated polybasic acid or its mixture with a saturated polybasic acid Acid or its mixture with a saturated polybasic acid and a polyhydric alcohol Understood. With an epoxy or arm no bandage modified condensation products are also included in the unsaturated polyester resin. in the generally, they are in the form of a mixture with a copolymerizable unsaturated monomer used

As unsaturated polybasic acid, for. The following can be mentioned, for example: maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid and the like. The following can be mentioned as saturated polybasic acid, for example:
Phthalic acid,
Phthalic anhydride,
Isophthalic acid,
Terephthalic acid,
Tetrachlorophthalic anhydride,
Hexachlorendomethylenetetrahydrophthalic acid,
Tetrabromophthalic anhydride,

Tetrahydrophthalic anhydride,

Hexahydrophthalic anhydride,

Succinic acid, adipic acid,

Azelaic acid, sebacic acid,

an anthracene-maleic anhydride adduct,

a Rosm maleic anhydride adduct,

Trimellitic anhydride,

Pyromellitic anhydride,

Methyl-endo-cis-BicycIo-fJZ.Z.lj-hept-

5-en-23-dicarboxylic acid and the like

As a polyhydric alcohol to be reacted with the above unsaturated polybasic component can be named for example:

Ethylene glycol diethylene glycol,

Triethylene glycol, polyethylene glycol,

Propylene glycol, dipropylene glycol,

Polypropylene glycol, 1,4-butanediol,

1,3-butanediol, 2,3-butanediol,

1,5-pentanediol, 1,6-hexanediol,

Neopentyl glycol,

2,2,4-trimethyl-1,3-pentanediol,

hydrogenated bis-phenol A,

2,2'-bis (4-hydroxyphenylene) propane,

an adduct or reaction product between
an alkylene oxide and
2,2'-bis (4-hydroxyphenylene) propane,

Pentaerythritol, glycerine,

Trimethylene glycol, 2-ethyl-1,3-hexanediol,

Phenyl glycidyl ether, allyl glycidyl ether,

Hexanetriol, sorbitol and the like

The copolymerizable to be used in combination with the above unsaturated polyester resin unsaturated monomers is selected from vinyl, vinylidene, allyl and other compounds with at least one α, / 3-ethylenic double bond in the Molecule. Examples of such unsaturated monomers include

Styrene, vinyl toluene,

Chlorostyrene, Λ-methylstyrene,

tert-butylstyrene, divinylbenzene,

Alkyl esters of methacrylic acid,

such as B. methyl methacrylate,

Alkyl esters of acrylic acid.

such as B. ethyl acrylate.

Vinyl acetate, acrylamide,

Methacrylamide, maleimide,

Diallyl phthalate, diallyl isophthalate,

Allyl acrylate, allyl methacrylate,

Diallyl maleate. Diallylitaconate,

Diallylsebacate, diallyladipate,

Diallyl glycolate and triallyl phosphate.
Compounds of the following general formula can also be used as the copolymerizable unsaturated monomer:

CH ₂ = CCO-A-O-CC = CH

wherein A is a residue of a compound having at least 2 hydroxyl groups at the ends of the molecule or a compound having at least one ester or ether bond in the molecule and at least two terminal hydroxyl groups; X stands for hydrogen, halogen or an alkyl group, such as e.g. B. methyl and ethyl, and π and m are integers from 1 to 3.
examples are

Ethylene glycol, propylene glycol,

1,3-butanediol dimethacrylate,

1,4-butanediol methacrylate,

23-butanedioi-,

2-ethyl-13-hexanediol dimethacrylate,

1,5-pentanediol, 1,6-hexanediol,

Neopentyl glycol dimethacrylate,

Glycerine trimethacrylate,

Dimethacryl (bis-diethylene glycol) phthalate,

Dimethacryl (bis-diethylene glycol) maleate,

Tetramethacrylic (bis-diethylene glycol) phthalate.

Triethylene glycol,

Tetramethylene glycol,
Polyethylene glycol dimethacrylate and
Trimethylol propane trimethacrylate.
These compounds have boiling points above that of styrene and are easy to handle. Furthermore, even if they are added in very small amounts, the crosslinking density can be increased and the heat distortion temperature in the resulting cured molded article can be increased,
ίο As a copolymerizable unsaturated monomer, dialkyl esters of maleic acid, fumaric acid and itaconic acid, such as. B. dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, diethyl itaconate and the like can be used,
is These copolymerizable unsaturated monomers can be used singly or in the form of mixtures of two or more.

In view of the water resistance and mechanical properties of the resulting molded article the above-mentioned unsaturated polyester resins to be used are preferably with an acid number not more than 60, in particular not more than 30, and a number average molecular weight of at least 200, in particular at least 1000, are used. A mixed weight ratio of unsaturated polyester resin / copolymerizable unsaturated monomer in the range of 80/20 to 30/70, • in particular from 70/30 to 40/60, preferred.

A polymerization initiator serving as a hardener is used as a catalyst in an amount of 0.2 to 3 Weight percent based on the mixture of the above unsaturated polyester resin and the copolymerizable one unsaturated monomers introduced.

Organic peroxides of the type which decomposes at a high temperature, the decomposition temperature required to achieve a half-life of 1 minute being above 150 ^° C., are preferably used as the polymerization initiator. As such an initiator, e.g. B. (the decomposition points are given in brackets):
Methyl ethyl ketone (171 ° C),
Cyclohexanone peroxide (174 ° C).
tert-Butylhydroperox'd (179 ° C).
p- (or m-) methane hydroperoxide (216'C),
Cumene hydroperoxide (255 ° C).

2,5-dimethylhexane-2,5-dihydroperoxide

(257 "C).

tert-butyl perbenzoate (170 ° C),
tert-butyl peracetate (160 ° C),
Di-tert-butyl peroxide (186 ° C),

Dicumyl peroxide (17 Γ C),
2,5-dimethyl-2,5-di (tert-butylperoxy) hexane

(179 = C).

2,5-dimethylhexane-2,5-di- (hydroperoxide)
(257 ° C),

Diisopropylbenzene hydroperoxide (205 ° C),
Di-tert-butyl perphthalate (159 ° C) etc.
These polymerization initiators can be used singly or in admixture of two or more.

It is possible to use a combination of an organic peroxide with a high decomposition temperature, like them are mentioned above, and a polymerization initiator with a low decomposition temperature at which the Decomposition temperature is not higher than 150 ° C, to use. As such an initiator with lower The decomposition temperature can be named, for example:

Benzoyl peroxide (130 ° C),

p-chlorobenzoyl peroxide (137 ° C),

2,4-dichlorobenzoyl peroxide (12rC),

Propionyl peroxide (118 ° C),

Lauroyl peroxide (114 ° C), acetyl peroxide (123 ° C),

tert-butyl peroxyisobutyrate (133 ° C),

Succinic acid peroxide (131 ° C),

Di-isopropyl peroxydicarbonate (88 ° C),

oi, oc'- Azobisisobu tyronitril (106 ° C) etc. ι ο

Such a low decomposition temperature polymerization initiator is preferred in an amount of up to 20 percent by weight, based on the total weight of the polymerization initiator used, used. It is also possible to use a hardening promoter or accelerator, such as. B. Co, Mn and To add Fe salts of organic acids, dimethylaniline, diethylaniline and the like.

As mentioned above, a filler such as z. B. magnesium carbonate, silicon dioxide, clay, talc and asbestos, a lubricant such as. B. stearic acid and Aluminum stearate, a thickening agent such as. B. finely divided silicon dioxide and bentonite, a dispersing agent, such as B. an anionic, cationic or nonionic surfactant, a lubricant, such as B. paraffin wax, chlorinated paraffin and fluorocarbon, a blowing agent of the nitroso, sulfohydrazide, Azo type or an inorganic agent, a urea, organic acid or blowing agent Metal salt type, a fire retardant such as B. tricresyl phosphate, triphenyl phosphate and antimony oxide, Fibers such as B. glass fibers, steel filaments, organic fibers and carbon fibers, a colorant such as. B. a dye and a pigment, a curing accelerator, a polymerization inhibitor, an antioxidant antistatic agent, stabilizer and the like can be incorporated.

If a thermoplastic plastic powder is added to the thermosetting plastic, the flow properties are improved and the moldability of the resin is improved, with the result that the appearance, the Toughness, impact resistance and other properties in the obtained molded product can be improved. The powder should have a particle size not more than 100 μm, preferably not more than 20 μm. Suitable thermoplastic resins are e.g. B. polyethylene, polypropylene, Polybutene, polyvinyl chloride, polyvinyl formal, polyvinyl butyral, polyvinylidene chloride, polymethacrylate, Polyamide, polycarbonate, polyvinyl fluoride, polyvinylidene fluoride or acetyl cellulose.

Such a powdery thermoplastic is preferred Plastic in an amount of 1 to 50 percent by weight, based on the total components, In the case of polyvinyl chloride, as the amount of the powder increases, the decrease in the mechanical strength is very low, and therefore it is possible to use the powder in an amount of up to 70 Percent by weight, based on the total components, to be introduced.

In the following, embodiments of the invention are described in which "parts" and "percent" are by weight unless otherwise specified.

example 1

25 parts of the unsaturated polyester resin solution, in which 2% of a lauroyl peroxide paste (LPO / DOP 1/1) had been dissolved, 14 parts of a powdery polyvinyl chloride resin, 55 parts of barium sulfate, 1 part of a liquid stabilizer composition (Zn-Cd-Ba organocomplex liquid), 5 parts of asbestos powder and 1 part of stearic acid were raw kneaded in a kneader mixer and an extruder to incoming kneading supplied. A preform was attached to the extruder outlet for extrusion molding, which was designed for a pipe with an outside diameter of 60 mm and a wall thickness of 3 mm. It was cooled so that the inside of the cylinder was kept below 50 ° C and the resin temperature was at The exit of the preform was set to 60 + 1 ° C by heating it. Continuous and uniform Extrusion turned out to be possible. Here, the viscosity of the resin was corresponding to one Needle penetration number of 280.

The temperature of the curing mold was kept at 150 ° C. and the pressing pressure was about 15 kgf / cm ² . The molding was completed with a residence time of 1 minute. When water heated to 100 ° C. was passed through the pipe thus obtained, defects such as deformation or leaks were not observed.

Example 2

An unsaturated polyester resin solution in which 2% of a lauroyl peroxide paste (LPO / DOP 1/1) is uniform had been dissolved, a powdery polyvinyl chloride resin, calcium carbonate, stearic acid and organic Synthetic fibers (a length of 10 mm) were continuously fed to an extruder so that the resin composition a composition of 25 parts of the unsaturated polyester resin solution, 5 parts of the powdery one Polyvinyl chloride resin, 65 parts of calcium carbonate, 1 part of stearic acid and 5 parts of the organic Had synthetic fibers. The deformation conditions chosen for the continuous operation of the extruder were the following:

Inlet temperature

of the extruder barrel 40 ° C

Starting temperature

of the extruder barrel 60 ° C

Initial temperature of the preform 68 ° C

Curing mold temperature 130 ° C

Compression pressure in the curing mold 15 kp / cm ²

Dwell time in the curing mold 1 minute

The obtained pipe-like molded product was excellent in surface finish and possessed excellent physical properties.

For this purpose 4 sheets of drawings

Claims (4)

Patent claims: 1. A method for the continuous extrusion of a mixture of a thermosetting plastic, a thermoplastic, fillers and a catalyst, in which the mixture in plasticized in a screw press below the curing temperature of the thermosetting plastic and condensed through an extrusion mold, in which the mixture is hardened of the thermosetting plastic is heated, characterized in that a mixture from 99 to 30 parts by weight of a mixture of an unsaturated polyester and a copolymerizable one unsaturated monomers in the weight ratio of 80:20 to 30:70 as the more thermosetting Plastic and 1 to 70 parts by weight of the thermoplastic material is used, wherein the thermoplastic is in powder form and is melted. 2. The method according to claim 1, characterized in that a thermoplastic material is used Polyvinyl chloride powder with a particle size of up to 100 μΐη is used. 3. The method according to claim 1 or 2, characterized in that the mixture in the screw press is plasticized in such a way that it has a flowability at the exit from the screw press, that of a needle penetration number of at least 20 under a load of 100 g for a loading period of 5 seconds according to ASTM D 5. 4. The method according to any one of claims 1 to 3, characterized in that the heating in the extrusion ^{mold at a temperature between 80 and 250 0} C of the mold wall at a pressure of up to 200 kp / cm ² and a dwell time between 1 second and 5 minutes is made.