DE2404658B2 - Process for the continuous extrusion of a mixture of a thermosetting and a thermoplastic material - Google Patents

Description

40

The invention relates to a method for continuous extrusion of a mixture of a thermosetting plastic, a thermoplastic 4 ^r "of plastic, fillers and a catalyst, in which plasticizes the mixture in a screw press below the curing temperature of the thermosetting resin and compressed is passed through a StrangpreDform, in the curing of the mixture v> thermosetting plastics material is heated.

The extrusion of thermoplastics, such as. B. polystyrene, polyethylene and vinyl chloride resins, has heretofore been widely used on various Areas have been carried out. However, the use of molded articles is made of thermoplastic Harzet / severely limited because they are inferior in heat resistance and mechanical strength to thermosetting resins.

From DE-PS 11 87 789 a process for eo extrusion of special thermosetting plastics is known, in which molding compounds in the mouthpiece of the extruder are heated to almost the curing temperature and the feed speed of the strand is regulated so that a μ dimensionally stable from the mouthpiece, but still not fully cured strand emerges. The plastic used, namely polyethylene with high molecular weight, is a Thermoplastic, but with the addition of thermal black and peroxide catalyst it becomes crosslinkable and Made curable This known method, however, has various disadvantages; So is because of the low reactivity of the compound a long curing form required The long curing form in turn requires a release agent or a mold release agent, for which a very complicated device is used must become. Furthermore, because of the long hardening shape, a high extrusion pressure is required Using a high extrusion pressure, however, it is difficult to obtain a homogeneously cured molded part to get, because due to the friction a local temperature increase and / or a reaction in the Extruder can take place.

Oie DE-OS 17 69 950 describes a method for continuous extrusion of the type mentioned. However, this is known method the thermoplastic in the form of synthetic fiber material and is used to reinforce the thermosetting plastic. He therefore goes with extrusion does not melt into the molten state, but retains its fiber shape. 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 a method of the type mentioned above using unsaturated polyether flawless To manufacture products using a process that 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 monomer 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 hardening by adding the thermoplastic, e.g. 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 Melt viscosity of the unsaturated polyester can be prevented due to the addition of the molten high molecular weight thermoplastic can; the viscosity is kept within a suitable range.

It is also possible to use the plastics under relatively extruded at low pressure. Due to the short curing form, the device can also combine

be panned.

According to a preferred embodiment, as thermoplastic a polyvinyl chloride powder with a particle size of up to 100 μπι used.

The mixture is preferably plasticized in the 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 mold is carried out at a temperature between 80 and 250 ° 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.

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

1 is a flow sheet illustrating continuous extrusion molding.

F i g. 2 is a sectional view of a through-hole, ng des Extrusion press used in the process,

Fig. 3, 4 and 5 sections of modifications of the Extrusion press according to FIG. 2 in which the extreme end is varied,

Fig. 6 is a graph showing the flow properties of a thermosetting phenolic resin illustrates the relationship between the needle penetration value and the temperature, and

Fig./ a curve showing the flow properties of a thermosetting unsaturated polyester resin compound illustrates the relationship between the needle penetration value and the temperature.

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

In the kneading step, a starting material ¹ comprising a thermosetting plastic, a hardening agent, a filler and other additives is mixed or melt-kneaded to form a homogeneous mass. In order to improve the flow properties of the plastic in extrusion molding and the quality of the resulting molded article, it is desirable to sufficiently carry out mixing and kneading in the kneading step.

With some thermosetting plastics, the curing reaction is allowed to take place 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 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 Premix components of the starting material in advance to some mixtures and finally add them to mix together a mixture.

The above kneading can be carried out by means of a high-speed disperser, a kneading roller, a hot roller, of a K.neter. a compression kneader, a Bunburv mixer, a Hcnschel mixer, an extruder of screw type o <l. the like.

In lien case, dall a screw-like extrusion press

is used in the kneading stage, it enables the Carry out kneading and extrusion stage one after the other in a continuous manner. In addition, a screw-type extruder is used for kneading advantageous in that, since the starting components are kneaded in a closed chamber, a Splashing or leakage of raw material can be effectively prevented. Of course it is possible that To carry out the kneading and extrusion stages separately,

ίο but if the raw material has a short pot life 'St 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

is liquid, conical 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 the

Extrusion stage fed In the extrusion stage this is done by the kneading stage

The raw material coming under atmospheric or elevated pressure is transported through an extruder The speed of rotation of the screw can be varied freely. The plastic is thereby produced by the heating effect of the cylinder of the extruder and The frictional heat of the plastic itself is softened and conveyed to the extreme end of the extruder

Then the plastic mixture is extruded through a preform and curing mold where the Deformation completed and the extruded material

jo 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

■ 35 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 adjust the deformation the temperature. For example, the curing mold entry temperature becomes lower Maintained altitude while maintaining the exit temperature high. It is also possible the whole Hold the curing mold at a constant temperature or to cool the entrance of the mold. the

Deformation occurs at an average temperature

in the form in the range from 80 to 250 ⁰ C, but what a

Cooling part of the mold does not exclude The hardened molded article is used for post-curing

th heated or cooled to correct for warpage and to the desired dimensions cut to obtain a final product.

The exact procedure is now based on the i.i the F i g. 2 to 5 shown device described in more detail.

A thermosetting plastic. Raw material 20 containing fillers, hardeners and other additives is fed to a hopper 2 of an extruder. The raw material becomes gradually and continuously by rotation of an extrusion screw 3, which is attached in a cylinder 1 (, uriferous kneading towards the outer end part (in Fig. 2 to the right) extrudicr: \ n At this point the raw material is due to the friction of the plastic molecules or the friction of the plastic components -

h) ponentc heated with 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 can be lines be heated by reading a heating medium.

The stranggepreOle material is then attached at the extreme end portion of the extruder by means of a fastening bolt 13 into a preform 11 gefer ^J c ". Here, the curing reaction is not triggered. An djeser point, the temperature of the plastic by passing is a heating medium through a heating 12 controlled so that the March u> 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 penetration ι, determined by bituminous substances) If the needle penetration value is less than 20, the flow resistance in the preform is too high.

The softened material extruded from the preform 11 is immediately placed in a curing mold 14 and 15: n 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, lim 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 Cylinders 16 and 17 used to move the mold halves perpendicular to the extrusion direction.

In the apparatus shown in Figure 3, the kneaded, thermosetting masses are extruded between a pair of heated conveyor belts 31 and 32. the η rotate from the extreme end of a cylinder 30. If this device is used as a curing mold, For example, a plate-like object 33 can be continuously produced.

For the production of pipes a device, m as shown in Fig.4. to carry out the Procedure are used. A tubular, softened material attached to an opening 42 of a Extruder 41 was preliminarily formed, is surrounded by a heated curing mold 43. Then a 4-, 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 -, n can be used. If this apparatus is used, tin is applied at an opening 52 of an extruder 51 preformed raw material through a curing mold 53 out, which is provided with a pressure-lowering chamber 55 and an air-permeable hole 56 The material is extruded while it is pressure lowering the curing mold 53 in tight Contact is brought.

In the continuous extrusion both the flow properties and the Härtungsei- are to characteristics of the mold material very important factors. Therefore, the physical and chemical properties of thermosetting plastics are described below.

In general, thermosetting plastics have flow properties as shown in FIGS. 6 and 7 are shown. 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 increased further and reaches the vicinity of point b, the needle penetration number decreases due to the hardening reaction, and the plastic is • c '! ^r1 ! - 'ig hardened and developed ^ ¹ ' toine ^ '"" ability, even with the application of pressure (point CJl

It is therefore necessary to give the plastic optimal flow properties by setting the heating temperatures of the extruder and the opening within such a range that a hardening reaction is not initiated. Furthermore, the flow properties of the plastic, i. h "the degree of needle penetration, suitably by adjusting the mixing ratio of the components of the molding material, e.g. H. a Mischiingsver ratio between the thermosetting plastic and the filler can be controlled.

The curing properties of a thermosetting Plastics vary depending on hit Λ γ:. I. * Catalyst, curing agent and Hartunpspromo tors, the mixing ratios of these agents, the temperature of the mold (id., the dwell time and other I .ictors.

Flow properties of an ordinary phenolic resin ¹ · are in 1 i g. 6, and FIG. Figure 7 is a graph showing the flow properties of a PnK unsaturated ester compound as illustrated in Example I below. shows.

The expression "unsaturated polyester resins as used here means condensation products of an unsaturated polybasic acid or its mixture with a saturated polybasic acid or its mixture with a saturated polybasic acid and a polyhydric alcohol. ^R having an epoxy or Aminove bond modified condensation products are also embraced by the unsaturated polyester resin. Generally, they are used in the form of a mixture with a copolymerizable unsaturated monomer.

As unsaturated polybasic acid, for. B. called: maleic acid. Maleic anhydride. Fumaric acid, citraconic acid, itaconic acid, etc. As the saturated polybasic acid, for example to be named:

Phthalic acid,

Phthalic anhydride,

Isophthalic acid,

Terephthalic acid,

Tetrachlorophthalic anhydride, hexachloroendomethylene tetrahydrophthalic acid ", Tetrabromophthalic anhydride, endomethylenetetrahydrophthalic anhydride.

Tetrahydrophthalic anhydride, hexahydrophthalic anhydride, Succinic acid, adipic acid,

Azelaic acid, sebacic acid,

an anthracene-maleic anhydride adduct, a rosin maleic anhydride adduct, Trimellitic anhydride,

Pyromellitic anhydride,

Methyi-endo-cis-BicycI & - [2 ^, l] -hept-5-ene-23-dicarboxylic acid and the like

As a polyhydric alcohol to be reacted with the above unsaturated polybasic component know for example called throwing:

Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol.

Propylene glycol, dipropylene glycol, polypropylene glycol, 1,4-butanediol, 1,3-butanediol, 23-butanediol,

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

Neopentyl glycol,

2,2,4-trimethyl-1 J-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) propar » _J

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 a ^ -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, diallyl itaconate,

Diallylsebacate, diallyladipate,

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

CH ₂ = CCOJA--

Il ο

0-CC = CH ₂ O

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 η and m integers from 1 to 3 are examples

Ethylene glycol, propylene glycol,

13-butanediol dimethacrylate,

1,4-butenediol methacrylate,

23-butanediol,

2-ethyl- I 3-hexanedioI-diniethacrylate, 1,5-pentanediol, 1,6-hexanediol,

Neopentyl glycol dimethacrylate, Glycerine trimethacrylate, Dimethacryl (bis-diethylene glycol) phthalate, Dimethacryl (bis-diethylene glycol) maleate, Tetramethacry ^ bis-diethyleneglyco-ophthalate, 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.
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.
ι; These copolymerizable unsaturated monomers can be used singly or in the form of mixtures of two or more.

With regard to the water resistance and the 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 the 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. B. (the decomposition points are given in brackets):
Methyl ethyl ketone (171 " C),
Cyclohexanone peroxide (174 ° C),
tert-butyl hydroperoxide (179 ° C),
p- (or m-) methane hydroperoxide (216 ° C),
4ί 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

(! 79 ⁰ C),

2 ^ -Dimethylhexane-2 £ -di (hydroperoxide)
(257 "C),

Diisopropylbenzoi 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 having a high decomposition temperature, as mentioned above, and a Polymensationsinitiators low decomposition temperature at which the decomposition temperature is not higher than 150 ⁰ C. As a . such an initiator with a low decomposition temperature can be named , for example:

Benzoyl peroxide (130 'C),

p-chlorobenzoyl peroxide (137 ° C),

2,4-dichlorobenzoyl peroxide (121 ° C),

Propionyl peroxide (l 18 ° C),

Lauroyl peroxide (114 ° C),

Acetyl peroxide (123 ° C),

tert-butyl peroxyisobutyrate (133 ° C),

Amber acid. eperoxide (131 ° C),

Di-isopropyl peroxydicarbonate (88 ° C),

λ, λ'-azobisisobutyronitrile (106 ° C) etc.
Such a polymerization initiator with a low decomposition temperature is preferably used in an amount of up to 20 percent by weight, based on the total weight of the polymerization initiator used. It is also possible to use a hardening promoter or accelerator, such as. B. Co, Mn and Fe salts of organic acids, dimethylaniline, diethylaniline and the like to be added.

Plastic, as mentioned above, a filler such as. B. magnesium carbonate, silicon dioxide, clay, talc and asbestos, a lubricant such as. B. stearic acid and aluminum stearate, a thickening agent such. B. finely divided silica and bentonite, a dispersant such. B. an anionic, cationic or nonionic surfactant, a lubricant such. B. paraffin wax, chlorinated paraffin and fluorocarbon, a blowing agent of the nitroso, sulfohydrazide, azo type or an inorganic agent, a blowing agent of the urea, organic acid or 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. For example, a dye and a pigment, a curing accelerator, a polymerization inhibitor, an antioxidant, an antistatic agent, a 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 greater than ΙΟΟμπι. 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 material is preferred in an amount of 1 to 50 Percentage by weight, based on the total components, incorporated. In the case of polyvinyl chloride, if as the amount of powder increases, the decrease in mechanical strength is very small, and therefore it is possible to use the powder in an amount of up to 70 percent by weight based on the total components, bring in.

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 l / l) had been dissolved, 14 parts of a

to powdery polyvinyl chloride resin, 55 parts of barium sulfate, 1 part of a liquid stabilizer composition (Zn-Cd-Ba organocomplex liquid), 5 parts asbestos powder and 1 part of stearic acid were raw kneaded in a kneader mixer and an extruder to

i> incoming kneading supplied. For extrusion molding a preform was attached to the extruder outlet, which was designed for a pipe with an outer diameter of 60 mm and a wall thickness of 3 mm. It was cooled so that the inside of the cylinder was unici

. (ι 'was held 50 ⁰ C and the resin temperature was adjusted by the heating to 60 ± TC at the output of the preform. A continuous and uniform extrusion proved to be possible. This was the viscosity of the resin in accordance with a Nadeleindringzahl of 280.

The temperature of the curing mold was maintained at 150 ⁰ C, and the press pressure was about 15kp / cm ^2. The molding was completed with a residence time of 1 minute. Was at 100 ° C

jo heated water passed through the pipe obtained in this way, defects such as deformation or leaks were not observed.

Example 2

js An unsaturated polyester resin solution in which 2% a lauroyl peroxide paste (LPO / DOP 1/1) was uniformly dissolved, a powdery polyvinyl chloride resin, Calcium carbonate, stearic acid and organic synthetic fibers (a length of 10 mm) were one Extruder continuously fed so that the resin composition has a composition of 25 parts of the unsaturated Polyester resin solution, 5 parts of the powdery polyvinyl chloride resin, 65 parts of calcium carbonate, 1 Part of stearic acid and 5 parts of the synthetic organic fibers. The ones for continuous operation The deformation conditions selected for the extruder were as follows:

Inlet temperature

of the extruder barrel 40 ° C
Starting temperature

of the extruder cylinder 60 ⁰ C

Initial temperature of the preform 68 ° C

Curing mold temperature 130 ^° C

Compression pressure in the curing mold 15kp / 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 hardening temperature of the thermosetting plastic and compressed by an extrusion mold is performed, in which the mixture is heated while hardening the thermosetting plastic, characterized in that a mixture of 99 to 30 parts by weight of a mixture of an unsaturated polyester and a copolymerizable unsaturated monomer in a weight ratio of 80:20 to 30:70 as the thermosetting one Plastic and 1 to 70 parts by weight of the thermoplastic material is used, whereby the thermoplastic material in powder form is melted in advance. 2. The method according to claim f. Characterized in that a thermoplastic material is used Polyvinyl chloride powder with a particle size of up to 100 μm is used. 3. The method according to claim 1 or 2, characterized in that the mixture is plasticized in the screw press such that it is at the outlet from the screw press has a flowability which corresponds to 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 one of the claims 1 to 3, characterized in that the heating in the extrusion mold at a temperature between 80 ° and 250 ° C of the mold wall at a pressure of up to 200 kp / cm ² and a dwell time between I. Second and 5 minutes.