DE2216718C2 - Process for modifying the rheological properties of polymers - Google Patents

Description

characterized in that one

(f) one in this reduced pressure zone in which the polymer is essentially liquid of the following materials:

(1); in monomer or monomers,

(2) a free radical initiator, or

(3) a combination of these components.

2. The method according to claim 1, characterized in that the polymer is a C2 to Cg olefin polymer is.

3. A method according to claim 1, characterized marked w characterized in that the polymer is a thermoplastic.

4. The method according to claim 1, characterized in that the polymer is high or polyethylene is low density.

5. The method according to claim 1, characterized in that the polymer is polypropylene.

6. The method according to claim 1, characterized in that the polymer is polymethylpentene, isotactic polypropylene, polyallomers, polybutylene or mixtures thereof are used.

7. The method according to claim 1, characterized in that the polymer is an elastomer.

8. The method according to claim 6, characterized in that the elastomer is an ethylene-propylene copolymer or an ethylene-propylene-diene terpolymer is.

9. The method according to claim I, characterized in that the monomer is unsaturated and as functional groups containing carboxyl groups or derivatives thereof.

10. The method according to claim!, Characterized in that that acrylic acid or a derivative thereof is used as the monomer.

11. The method according to claim 1, characterized in that that maleic anhydride or a derivative thereof is used as the monomer.

12. The method according to claim 1, characterized draws that as M ^ 'iomer Glycidylacrylai

used.

13. The method according to claim 9, characterized in that the resulting modified polymer then by further reactions in the form of esterification, neutralization, amide formation or hnidbildung is modified.

14. The method according to claim 1, characterized in that the free radical initiator in Absence of free radical reactive monomers is introduced.

15. The method according to claim 1, characterized in that the free radical initiator in Presence of free radical reactive monomers is introduced.

16. The method according to claim 1, characterized in that the entrance part of the reaction zone is under relatively low pressure.

17. The method according to claim 1, characterized in that the polymer consists of a mixture of a thermoplastic and an elastomer.

As is well known, polymers can be modified in an extruder by adding them at increased rates Treated temperatures with or without the addition of an initiator. It is also known in those in Extrusion takes place reactions to graft monomers or polymer chains onto the base polymer.

It has now been found that extraordinary advantages in terms of process flow and product quality can be achieved by designing and using special reaction zones and conditions inside an extruder. One can use relatively low temperatures and high throughputs work. The resulting grafted products are new and have unusual properties. Furthermore, the economy of the process is improved.

The invention relates to a method for modifying theological or chemical and rheological Properties of a polymer that is solid at room temperature

a) Introduction of the polymer into an extruder with a movable displacement screw various Core cross-section delimiting a reaction zone,

(b) creating an overpressure in the extruder during the passage of the polymer,

(c) Application of heat in addition to mechanical working to turn the polymer into liquid form convict,

(d) Transporting the liquid polymer into a reaction zone within the extruder in which the polymer volume is regulated so that it is smaller than the volume of the reaction zone, which creates a reduced pressure in this zone.

(e) Onward transport of the resulting modified polymer through the eastern extrusion line,

which is characterized by it. that he

(f) into this reduced pressure zone in which the polymer is essentially liquid, one of the

introduces the following materials:

(1) a monomer or monomers,

(2) a free radical initiator or

(3) a combination of these components.

The process of the invention comprises the formation and use of a special reaction zone within an extruder, in which the reaction conditions are so chosen and maintained may that iran is missing momentarily intense added reactants achieved with a polymer, which makes the achievement more special Theological changes to a polymer moving through the extruder are permitted

Modified polymers, especially polyolefins with improved flow properties and occasionally improved Adhesive properties compared to those of the polymeric base material, e.g. B. the polyolefin, which is used as starting material, are controlled in the extruder by a, often a Get an inclusive reaction. To do this, an initiator is used under conditions of intensive mixing injected, whereupon you notice noticeable changes; rheological behavior, d. H. the molecular weight distribution, take place in the starting polymer. According to some 2ϊ embodiments, monomers are also based on the Basic material! grafted on during the breakdown process. In these cases you get excellent new ones Graft polymers with favorable melt flow properties and other useful properties.

Three particularly important process parameters that can be adjusted in a short time are shear force. Pressure and temperature. It has now been found how such regulations are to be made so that various surprising and useful results result.

Ancillary reactants are used in practicing the invention introduced into the special reaction zone under conditions of maximum effect result in a minimal amount of time. A polymer can not only be used in its Theological Properties, i. H. in Molecular weight and flow properties can be changed, but at the same time can also be chemical Modifications take place. For this purpose, additional starting materials are chemically combined with the polymer implemented, in particular new grafted polymers with shorter chain length a's the starting polymer receives.

The figure shows a schematic view of a preferred extruder for performing the Procedure according to the invention, in which an initiator is fed to a decompression zone.

Sealing or closing off the reaction zone is essential when carrying out the invention high pressure and high shear or the low «pressure reaction zone with a device such. B. a cap which closes the part of the reaction zone that has been converted. Such a device will generally used in conjunction with a subsequent depressurization. According to a preferred Embodiment, the cap consists of a part of the screw core, which has an enlarged cross-section, whereby it is prevented that gaseous reactants can easily leave the reaction zone. One a suitable device is, for example, a commercially available Egan mixer.

The sealing of the reactants is preferably accompanied by a subsequent venting of gas at reduced pressure, with vaporous components being removed. The capping prevents also that vaporous reactants are prematurely removed from the reaction zone. Through the Venting or gas extraction prevents unwanted pressure increases through reactive vapors caused corrosion, the formation of malodorous products, corrosive products and easy decomposable products.

The method according to the invention can be applied to all polymers that are used in an extruder can be processed, especially on thermoplastics such as nylon, polyester, polycarbonate, technical Plastics and acetals. It is particularly suitable for polyolefins with 2 to 8, preferably 2 to 5 Carbon atoms including copolymers of olefins and other monomers, e.g. B. vinyl monomers, in which the olefinic part is the predominant component

The method is also applicable to elastomers, especially polyolefins, but also to ^ ^! : on Silicon-Elasiomcrc. A difference should be made between polymers whose properties are largely determined by the ethylene content and those polymers whose properties are largely determined by the content of r * i C3 - Cg olefin.

This distinction lies mainly in the fact that, under certain conditions in the reactor, polyethylene and ethylene-containing polymers are crosslinked and degraded at the same time, under which Cj and higher polyolefins do not crosslink but are degraded.

In the following description, therefore, occasionally Attention is drawn to the different procedural conditions that are to be applied if the essential Polymer properties can be determined by the ethylene content.

The inventive method is also applicable to all types of elastomers that are in a Extrusion press can be processed. As examples are

natural rubber,
Polyisobutylene. Butyl rubber,
Chlorobutyl rubber, polybutadiene,
Butadiene-styrene rubber,
Ethylene propylene elastomers,
Ethylene-propylene-diene terpolymers
and mixtures of these with one another and with thermoplastic polymers. Mixtures of elastomers and thermoplastics in any quantitative ratio are particularly improved by the process according to the invention.

In particular polyolefins, both plastic and elastomeric, but also other thermoplastics are used for purposes in which the property of a ^ uten flowability during the Processing is important. This is especially the case in the production of foils, fibers and in Injection molding.

In numerous te.! Mixed applications, one narrow molecular weight distribution is more favorable than a broad one. The increase in shape defined below the swell) is a useful measure for measuring molecular weight distribution. Generally show narrow molecular weight distributions have a tendency to lower viscosities and improved flow properties at.

The best way to achieve the tightness you want

Molecular weight distribution would be in a control of the polymerization in such a way that this Molecular weight distribution is obtained directly. So far, however, there is no effective method for the appropriate Polymer synthesis known.

It has now been found that with numerous polymers, particularly polyolefins and especially Polypropylene, polybutylene and, within certain limits, also polyethylene (if there are no excessive crosslinking reactions) the molecular weight distribution can be narrowed by the application of controlled procedural measures, which are carried out using the Embodiments of extrusion presses described below provide excellent mixing of the Effect dispersion of the reactants.

Once the polymer is in the molten state, at a suitable temperature and at a noticeable level Reduced pressure compared to a first metering zone of the extruder, initiators can be different Kind are added, and there then occurs very rapid diffusion or dispersion of the initiator or other Reactant in the polymer. This makes it possible to have an intensive reaction with very short residence times to achieve in the reaction zone.

In most cases it will be due to the controlled Degradation of the length of the individual polymer molecules is roughly the same, which results in the desired narrow molecular weight distribution and, at the same time, a reduction in molecular weight result. Crystallinity and other desirable properties of the polymer are retained.

Instead of or in addition to the change in the molecular weight distribution described above reactive and / or polymerizable monomers can be used in the presence of suitable catalysts or initiators (usually the same compounds that break down the polymer cause) to be introduced with the monomer to form a plug and usually, but not rigid, a To cause polymerization of such monomers at the active * o sites determined by the special Reaction conditions arise in the reaction zone at this point in time on the polymer.

The method according to the invention is particularly remarkable in that it is the first time a * 5 Method for the simultaneous narrowing of the molecular weight distribution, which is caused by the smaller increase in shape of the polymer or the better flowability can be determined, and to achieve one within a provides a wide range of grafting degrees

Much of the resulting graft polymers are new. For example, no grafted polypropylene with 0.05 to 20 wt of the base polymer, and made with gains that are at least 0.05 units lower than the base polymers.

Graft polymers with a relatively narrow molecular weight distribution are new and advantageous. The term "relative" refers to the base polymer that comes directly from a synthesis, ie before any measurable cleavage, degradation or chain termination has occurred

Crosslinking is not a problem with most C ₃ to Ce polyolefins. In the case of ethylene-containing polymers or polyethylene, slightly different processes can be used to avoid crosslinking. This includes the creation of activated points on the polyethylene by initiators that do not promote networking, e.g. B. gaseous oxygen, organic tin compounds, organic sulfur compounds, heat stabilizers, acid anhydrides.

Furthermore, either the initiators or the monomers can be separated from the other component, d. H. introduce the monomer or initiator, and before this, so that the reaction leads to grafting rather than to grafting Crosslinking furthermore, the temperature can be controlled in such a way that crosslinking is kept to a minimum, will.

The method according to the invention is very flexible, it is in numerous variants according to the respective intended purposes feasible.

Of course, you can also add monomer mixtures, whereby one obtains drop copolymers, in which the graft chains comprise at least two different monomers (apart from the monomers of Base polymers).

You can also graft substances that do not form polymers. For example, you can use fabrics grafts that act as antistatic agents, light stabilizers, anti-photodegradation agents, nucleating agents, flame retardants, Heat stabilizers, plasticizers, lubricants or dyes work. One way of doing this A variant consists in providing an unsaturated site in conjunction with a steric one Hindrance in the monomer so that only one monomer is grafted onto a reaction site. The polymerization is unfavorable. Monomers that react directly with the functional grafting materials, via too the above functions are satisfactory.

The preferred class of monomers for the preparation of graft polymers according to the invention has functional ones Groups such as B.

Carboxylic acid groups, hydroxyl groups, nitrile groups, amine ester groups, polyether sequences, imide groups, amide groups, glycidyl groups, epoxy groups
next to at least one multiple binding.

The functional groups can then be added in the extruder or later with other modifying agents implemented to change the properties of the graft polymer and to heat stabilizers, Light stabilizers or absorbers, nucleating agents, lubricants, anti-photodegradation agents, flame retardants, To give antistatic agents or plasticizers.

The graft polymer usually contains 0.02 to 20 % by weight, preferably 0.1 to 10 and 0.2 to 8% by weight Graft portion |

If suitable monomers are used for the production of the graft components, in addition to the change in the theological properties already mentioned, advantageous improvements in the adhesive properties can be achieved of the polymer. According to the invention you can § therefore produce polymers that are practically all :. Substrates adhere, even when using relatively | little graft component, ie 1% or less, § based on the total polymer. Numerous non-polar polymers such as B. the polyolefins do not adhere well to metals and other materials such as plastics, | z. B. nylon, polyesters, fluorine-containing polymers. Furthermore | they do not use dyes, paints, coatings,?;

Metal plating, imprints on. By modification with the corresponding monomer according to the invention, products can be obtained which possess all of the above properties that the base polymer lacks.

The materials modified in this way can nevertheless be used for all purposes for which the unmodified Material (base polymer) is used, advertise used. For example, they can be foamed, too Plastics and powders processed, dispersed into colloidal mixtures, emulsified, extruded and in be deformed in any way.

The preferred monomers for modification are unsaturated mono- and polycarboxylic acids (C3 to Cio) with preferably at least one olefinic double bond, as well as the anhydrides, salts, esters, ethers, Amides, nitriles, thiloe, thioacids, glycidyl, cyano, hydroxy, glycol and otherwise substituted Derivatives of these acids.

Ais examples of acids, anhydrides and acid derivatives / u te are:

Maleic acid, fumaric acid, himic acid,
Itaconic acid, citraconic acid, acrylic acid,
Glycidyl acrylate, cyanoacrylate,

Hydroxy-Ci to CM-alkyl methacrylate, acrylic polyether, acrylic anhydride,
Methacrylic acid, crotonic acid,
Isocrotonic acid, mesaconic acid,
Angelicic acid, maleic anhydride,
Itaconic anhydride, citraconic anhydride,
Himic anhydride,

p.o-endo-methylene-zM-tetrahydrophthalic anhydride),

Acrylonitrile, methacrylonitrile, sodium acrylate, calcium acrylate and
Magnesium acrylate.

Other monomers, alone or in admixture with one or more of the carboxylic acids or carboxylic acid derivatives can be used are the Cr to Cyi vinyl monomers, e.g. B. acryloxide, acrylonitrile and monovhiyl aromatic compounds, d. H. Styrene, Chlorostyrenes, bromostyrenes, «-methylstyrene, vinylpyridines and the like

Other useful monomers are C1 to C50 vinyl * 5 esters, vinyl ethers and allyl esters, e.g. B. vinyl butyrate, Vinyl laurate, vinyl stearate, vinyl adipate, and the like, as well as Monomers with two or more vinyl groups, e.g. B. divinylbenzene, ethylene dimethacrylate, triallyl phosphite, Diallyl cyanurate and triallyl cyanurate.

Thus, in general, practically all materials which can react with the base polymer, in particular under free radical conditions and at the melting temperature of the base polymer, are suitable for carrying out the invention

A large part of these materials owns in addition to the Unsaturation is a functional group. However, the functional group need not be present, see as For example, the monomers styrene or ethylene, which are also suitable. so

It has also been found that in the production of graft polymers according to the invention, when used in sufficiently small amounts, they act as core substrates and thus shorten the period of time within which the polymer cures and the solid plastic is formed from the melt . These proportions also increase the clarity of the polymers; they are therefore used in the appropriate cases, e.g. B. in the production of foils and bottles. The core-forming effect is observed at very low concentrations of the graft polymers as an additive in other polymers.

The usual additives can of course also be used with the modified polymers. These include conventional heat stabilizers, lubricants, antioxidants, antistatic agents, dyes, Flame retardants, plasticizers, preservatives, processing aids, as well as fibrous and non-fibrous ones Fillers or reinforcing agents including glass, silica, plastic powder, metal powder and wire.

The usefulness of the graft polymers produced according to the invention is very extensive, since these Products have good binding and adhesive strength. They can be printed and decorated, furthermore electroplated, hot-pressed, painted and coated by vacuum metallization. From the polymers produced according to the invention, in particular

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Polypropylene

Manufactured tapes are particularly suitable for fastening nails to nail straps. Such tapes are also suitable for lacing and other purposes where good adhesion and strength are required are, especially if they contain 10 to 70 wt .-% elastomer.

For further processing, the polymer products produced according to the invention can be blow molded with extrusion, be preformed or calendered, by centrifugal casting, for overmolding, for powder coating, be used for transfer molding, compression molding or extrusion, they can also be used for Foam processed, injection molded, mechanically deformed, rotary pressed, pressed under reinforcement, be thermally deformed or impregnated in strips. The polymers produced according to the invention are suitable in particular as coatings or film-like laminates on other polymers, for example as laminates made of polypropylene grafted with glycidyl acrylate.

It should be emphasized that the base polymers also include substituted polymers. The backbone of the Polymers can therefore before grafting through functional groups such as chlorine atoms, hydroxyl groups, Nitrile groups, ester-amine groups may be substituted.

Furthermore, polymers which are grafted with monomeric substances, in particular those with functional carboxylic acid groups, can additionally be crosslinked in a conventional manner or can be subjected to ionomeric crosslinking using metal salts.

What is desired are products that initially flow very easily during processing and then harden very rigidly after processing through crosslinking. The products produced according to the invention can be used in this way. If crosslinking is an option, the molecular weight of the polymer can be drastically reduced by using larger amounts of the free radical initiator, ie from 0.05 to 5% by weight, based on the starting polymer. Polymers with limiting viscosities of 0.8 and less, ie 500 to 6000 cP, preferably 1000 to 500 and 2500 to 4500 cP, are particularly suitable for crosslinking after the grafting described.

These low molecular weight polymers can not only be crosslinked, but also emulsified and otherwise processed for the production of surface coatings.

According to the invention thus polymers may not only for the purpose of reduction in molecular weight and narrowing treated the molecular weight distribution and thus traditional plastic uses are supplied, but it is also possible to prepare polymers which are suitable as coating agents and additives to fuels, lubricating oils, lubricants, and spray oils a's viscosity modifiers, Sludge inhibitors and antioxidants are suitable.

For example, -olefins, e.g. B. ethylene-propylene copolymers, whose viscosity has been reduced to some extent and which have a narrow molecular weight distribution obtained excellent additive properties when used in lubricating oils within a wide temperature range.

The modified polymers according to the invention are excellent additives. You grant other polymers, even if present in small amounts, have unusual properties even if these other polymers differ significantly from the modified additive in terms of melt flow rate differentiate. In general, the polymers prepared according to the invention can be used with advantage with other polyolefins, d. H. Thermoplastics and elastomers in amounts from 0.001 to 99% by weight, preferably 0.01 to 20 and 0.01 to 10 wt .-%, based on the weight of the resulting mixture, mix.

According to one embodiment of the invention, a polymer of O2 to Ce mono - «- olefin" or a copolymer thereof is grafted with acrylic acid. The polymers of Cr to Ce mono-α-olefins are referred to as polyolefins, and this designation includes in the description of the copolymers of Cj and Ce mono-a-olefins with one another and with other monomers and the homopolymers.

Polymers containing diolefins such as butadiene or isoprene are also suitable. Dio polyolefins are mostly made using a catalyst with transition metal, but they can also be made with Phillips catalysts, cationic or anionic initiators or by the free radical method under high pressure. The processes for making the C2-Ce polyolefins are known and do not form part of the invention.

Suitable polyolefins both plastic and elastomeric in nature are low or high density polyethylene, polypropylene, polybutene-1, poly-3-methylbutene-1, poly-4-methylpentene-i, mixed polymers of monoolefins and other olefins (mono- or diolefins) or vinyl monomers such as ethylene-propylene mixed polymers, or with one or more other monomers, e.g. B.

Ethylene-propylene-diene terpolymer, Ethylene / butylene copolymers, Ethylene / vinyl acetate copolymers, Ethylene / ethyl acrylate copolymers, Propylene / 4-methylpentene-1 copolymers.

"Copolymers" or mixed polymers are products made from two or more monomers or substituted derivatives thereof understood.

The polyolefins suitable for practicing the invention contain propylene and / or ethylene; H. the preferred materials are polypropylene and polyethylene. The starting polymer of the process according to the invention preferably has a melt index (MI) of 0.1 to 40, preferably vcsi 1 to 40 and from 1.5 to 40, or a melt flow rate

(MFR) / between about 0.1 and 50. preferably / between 0.1 and 5.0 and between 0.5 and 2. These Melt flow rates roughly correspond to average molecular weights (viscosity average) from about 150,000 to 700,000.

In the manufacture of usually solid polymers from 1-olefins, controls are often used uses certain theological properties. One of these theological properties is the melt index or the melt flow rate, which characterizes the processability of the polymers and an approximate indication of the molecular size weight gives. The Schmcl / index of polyethylene becomes usually determined according to ASTM D-12J8-h5T. In This test gives the extrusion speed in grams per 10 minutes (through a mouthpiece of 2.086 mm diameter and 8.001 mm length) at ISO "C determined under the weight of a piston, the diameter of which is 9.465 mm and which together with his stamp 2i6O g wicgi.

The melt flow rate (MFR) of polypropylene is determined using the same procedure, however, the temperature is 230 C (ASTM D-1238-65T).

The one used to determine the melting line The device is called "Deadweight Piston Plastometer" in the ASTM manual.

Generally, polypropylene from the reactor has a melt flow rate below 1. while with polyethylene from the reactor the melt index is about 0.4 to 40.

The preferred monomers based on Ci- bis Ce polyolefins and other polymers are grafted on are maleic anhydride. Acrylic acid. Methacrylic acid. Glycidylacryl.it. Acrylamide. Hydroxy-d- bis Cio-alkyl methacrylates and their derivatives. Further Usable monomers are mentioned in the description. Other monomers can be mixed with them such as B. MaleinsaLireanh> (!: id. Styrene. Acid esters. Salts and the like, maleic anhydride and styrene, and maleic anhydride and acrylic acid, are used in the manufacture of maleic anhydride grafted polymers preferred to the use of maleic anhydride alone.

The grafting reaction is initiated by a free radical initiator, which preferably consists of a organic per compound. These are particularly preferred peroxides

t-butyl perbenzoate, dicumyl peroxide,
2,5-dimethyl-2,5-di-tert-butylperoxy-

3-hexyne (Lupersol 130),
A, ix'-bis (tert-butylperoxy) -

diisopropylbenzoi (VulCup R)

or other free radical initiators having a 10 hour half-life temperature of more than 8O ⁰ C, or mixtures thereof. In general, the higher the decomposition temperature of the per-compound, the more favorable it is

According to the figure, in an extruder 1 with a charging zone 2, a reaction zone 3 and an embodiment of the grafting according to the invention is carried out in a final dosage zone 4

Polypropylene is introduced into the feed zone 2 of the extruder 1 via a feed hopper 5 The extruder screw 6 in the feed zone 2 can be designed in various conventional ways, for example with a charging part 7, an upper passage part 8 and a first metering part 9.

hi ilt. Beschifkungs / one 2 is made of polypropylene by heating devices IO to a cylinder temperature heated from 204 to 34 ° C, preferably 204 to 288 ° C.

The extruder screw 6 has a core that is reduced to deginning of the reaction zone 3 Has cross section 11. This creates additional volume and a pressure drop in reaction zone 3 generated, d. H. a decompression, so that a specific part of the polymer does not undergo the usually high pressure exposed in the extruder.

A feed line 12 connects the reaction zone to the supply of initial ·> r, which preferably consists of a peroxide, and an active monomer (in some cases the peroxide is used alone). In the case of the special embodiment, the monomer consists of acic acid and the initiator consists of VulCup R ((.

By injecting the initiator or the mixture from initiator and monomer at this point of low pressure in reaction zone 3 becomes one Careful dispersion of the initiator in the polypropylene effected in an extremely short time, resulting in noticeable cleavage or degradation of the polypropylene. Appropriate settings of the polypropylene feed rate and screw speed must be maintained.

According to the embodiment, the initiator and acrylic acid are introduced into the reaction zone as a liquid mixture 3 introduced. If only a degradation is sought, one gives only initiator or one dissolved in a solvent Initiator of reaction zone 3 to.

It has been found that a noticeable degradation of the polypropylene takes place when the counterpressure against the liquid mixture of initiator and acrylic acid in the feed line 12 is less than about 7 bar overpressure, preferably about 0 bar.

The pressure in the feed line 12 therefore gives an indication of whether the polypropylene feed speed and screw speed are set appropriately for the respective product.

The part of the extruder that is heated by the heating devices 13 has a temperature between about 71 and 232 ° C., preferably between 121 and 232 ° C. The extruder screw 6 in the rear part of the reaction zone 3 can have any cross-section of the core, which is appropriate for pumping and optionally additional mixing and which allows the remaining reactants to complete the reaction.

The decompression part 3a of the screw is immediately followed by a transition part 3b with a gradually increasing cross section of the screw core and finally a metering zone 3c with a constant cross section of the screwdriver core.

The extruder screw 6 then has a melt seal (also called a cap) 14, which prevents the free escape of initiator and acrylic acid from the reaction zone 3.

The screw 6 also has a second decompression zone 15 behind the cap 14.

A vent 16 (to which a vacuum can optionally be applied ) is located above the decompression zone 15 for the purpose of extracting gases or vapors. If you work without the vent 16, the cap 14 and the decompression zone 15 can be omitted.

The grafted copolymer or homopolymer mixture is then passed through an end metering zone 4, from which it is extruded via a mouthpiece 17 at the end of the extruder 1.

The cylinder temperature, the ierungszone by the heaters Ii ii Endikv 4 is prepared, is / wipe 177 and 288 ⁰ C, preferably between 177 and 232 ° C.

The extremely high degree of mixing which characterizes the process according to the invention is noticeable Polymer degradation made visible. This polymer degradation is noticeable through a substantial increase the melt flow rate or melt index of the copolymer compared to the base polymer. The narrowing of the molecular weight distribution can be seen from the fact that the shape increase in grafted copolymer is lower than the base polyolefin used to make the copolymer was used.

Some high molecular weight polymers, e.g. B. the polyolefins, when pressed through a capillary mouthpiece of a relatively short length, an Exiiuuai.dcSScn diameter is larger than the diameter of the capillary.

This property of the polymer is referred to as "swell" and is numerically im The ratio between the diameter of the extrudate and the diameter of the capillary is expressed (where both extrudate diameter to capillary diameter and capillary diameter to extrudate diameter used). According to the description, the increase in shape is defined as follows:

/ AY
Increase in shape = (---,

wherein

Dc = extrudate diameter
Do = capillary diameter

The numerical value of the increase in shape is also dependent on the geometry of the rheometer in which the Polymer is pushed through the capillary, depending. See the numbers given in the tables below Values were obtained with a rheometer, the rheometer cylinder of which had an internal diameter of 9.5 mm. The specified temperature was set to ± 1. rC exactly, the polymer was through a capillary with an inner diameter of 0.7666 mm and a length of 25.55 mm. Of the The entry angle of the capillary was 90 °.

The measurements were carried out by pushing the polymer through the capillary using a punch pressed that constant speed or

constant shear rate (Y) from 13.5 to 3383 sec- 'worked. The polymer was through the

Capillary in normal room temperature (21.1 to 26.7 ° C)

pressed

The measurement of the increase in shape is often used to determine a

to obtain a rough measure of the molecular weight distribution in polyolefins. Polymers with a high gain in shape have a broader molecular weight distribution than polymers with a Teringer gain in shape.
The polymers according to the invention thus have increases in shape which are less than the increases in shape of the base materials. They are products of a statistical cleavage process which leads to a reduction in molecular weight and therefore have a

narrower molecular weight distribution than the base polymers,

It should be noted that grafted polymers of unusually high melt flow index (i.e. about 20 to 1000) can also be produced using a starting polymer with a Melt flow index of the same range, with conventional grafting and / or additional degradation.

The free-radical initiator is used in amounts corresponding to 0.05 to 5% by weight, preferably 0.02 to 2% by weight and 0.02 to 1.0% by weight, based on the polymer, are used

The monomer to be grafted is used in amounts of from 0.01 to 100, preferably from 0.05 to 50 and from 0.1 to 25% by weight, based on the base polymer, applied. A particularly preferred range is between 0.1 and 1.5%. With these amounts, high grafts are achieved. The adhesive properties are also greatly increased compared to the base polymer, even with such small amounts of grafts.

In general, the initiator and monomer are mixed and added at the same time, with one exception the cases in which the polymer is polyethylene or a predominantly ethylene-containing copolymer

The new graft polymers produced according to the invention are characterized by various important properties marked These include:

(1) A melt flow index of 3 to 1000, preferably more than 10 to 250, in particular from 20 to 250, which is at least 50% or more, preferably 100% or more and especially around is at least 150% or more higher than the melt index or the melt flow rate of the starting polymer having a melt index or a melt flow rate of Non-liquid up to 150 (measured according to ASTM

D-1238-65T),

Content of polymerized graft comonomer from 0.02 to 20% by weight, preferably from 0.1 to 10 and from 0.2 to 8% by weight, based on the total amount of the graft copolymer (here za mention that the beneficial effects of grafting at a relatively low level of grafted comonomer, i.e. H. of 1% and less, to be observed).

An increase in shape of at least G.05, preferably at least 0.1 unit less than the increase in shape of the base polymer, particularly preferred 0.15 units less than the base polymer.

example 1

Polypropylene with a melt flow index of 0.4 was introduced into an extruder via the feed hopper according to the figure in the one with a side opening provided supply line 12 was a mixture of acrylic acid and peroxide (VulCup R) at the various NEN batches in the amounts given in Table I. Filled in With mixtures A to G, acrylic acid and peroxide were applied with practically no counterpressure the supply line 12 added, which is above the Decompression zone of the snail was.

For mixtures H through K, however, acrylic acid and peroxide were put into a standard extruder introduced wherein the reaction zone was filled with polymer and a considerable pressure of the melt was present against the feed line. The remaining Conditions under which the graft copolymerizations were carried out are given in Tables I below and H can be found.

Table I. product B. C. D. E. F. O (without pressure) A. 271-254 271-254 271-254 271-254 271-254 271-254 217-254 160-204 151-204 151-204 146-204 151-204 151-204 Barrel temperatures ^{, 0 C} 151-204 232-204 232-204 232-204 232-204 232-204 232-204 Loading zone 232-204 40.8 43.1 44.9 43.1 -40.8 40.8 Reactor zone 41.7 160 160 160 160 160 160 Dosing zone 160 Output kg / hour 15th 15th 15th 30-35 15th 15th Screw speed, 15th Rpm 6.22 6.46 6.30 6.35 -8.9 9.92 g peroxide / 1000 g 3.26 Acrylic acid 5.85 5.85 5.29 6.03 -7.5 8.60 amount of acrylic acid injected, 2.66 Weight ·· / · 94 86 84 95 -85 87 Total amount of acrylic acid 81 0 0 0 0 0 0 in the prod., wt .-% 0 % Acrylic acid conversion Melt pressure against Supply line, bar

Table II product I. J K (with full pressure) H 271-254 271-254 271-254 271-254 149-204 149-204 149-204 Barrel temperatures ^{, 0 C} 149-204 232-204 232-204 232-204 Loading zone 232-204 41.7 36.3 41.3 Reactor zone 36.3 160 160 ! 60 Dosing zone 160 15th 15th 15th Output kg / hour 15th 6.70 7.83 9.96 Screw speed, rpm 3.84 5.82 6.96 8, -iN; g peroxide / 1000 g acrylic acid 3.18 87 89 90 amount of acrylic acid injected,% by weight 83 -400 150-300 300-500 Total amount of acrylic acid in the product,% by weight 150 % Acrylic acid conversion Melt pressure against supply line, bar

It has been found that when grafting monomer is incorporated in amounts of about 5% by weight or relatively high degrees of conversion for the grafting are achieved less of the entire graft polymer. At about 15 to 20 wt% the conversions are lower; H. they are 50 to 80%.

As can be seen from the tables above, the percentage is of acrylic acid in the copolymer in relation to the injected minge. The overall conversion of the Acrylic acid in polymer is relatively high under both approaches.

Example 2

The mixtures obtained according to Example 1 were examined. Careful dispersion and mixing of the initiator, which causes a noticeable degradation of the polypropylene in mixtures A to G is evident from the lower mold gain and the higher melt flow rate.

Table III

In contrast, the polypropylene-acrylic acid graft copolymers show H to K increase in shape which is either equal to the increase in shape of the polypropylene base material or higher, they suffered very little molecular weight loss. From this you can see one that there is no noticeable degradation in the mixtures H to K during the grafting of the acrylic acid.

From the increase in the melt flow rate of the grafted copolymers A through G compared to the melt flow rate of the base polymer, it can be seen that a noticeable degradation has occurred, this im In contrast to the slight increase in melt flow rates for the grafted copolymers H to K.

The experimental data for shape gain and melt flow rate are in the following Tables III and IV summarized (the acrylic acid content has been increased to the nearest integer or rounded):

product > .5 .35 B ( : ι I. ;> E. J F. G reason I. .35 material .42 11.2 0.6 0.2 49.7 J 1.4 13.3 MFR 0.4 ( , 50 6 ( J t 6th 9 9 Weight- "," Acrylic acid, approx. 0 .67 Shape increase at 204 ⁰ C 1.35 , 35 , 42 1.50 1.35 1.20 Y = 13.5 sec ' 1.Ο 1.35 , 35 , 42 1.50 1.35 1.27 Y = 33.8 Sck ' Ι.76 1.35 , 35 , 42 1.50 1.35 1.42 Y = 67.7 sec ' 1.85 1.42 , 35 , 42 1.50 1.50 1.42 Y = 135.3 sec ' 1.94 1.76 , 59 .59 - 1.85 - Y = 338.3 sec ' 2.53 Table IV product Il K

Weight- "., Acrylic acid. Approx.

0.9
6th

0.8
6th

continuation Example 3 22 16 718 18th I. J K properties Izod- fzod impact strength, cm kg / cm secant train Warmth- 17th E according to a filler-containing, unmodified polypropylene Notch (ft · Ib / in ■ 5.4) Bending strength deformable 1.67 1.67 1.76 Example 1 with unmodified polypropylene homo- .'i len homopolymers. The test results are in tenacious module temperature b. Shape increase at 204 ⁰ C product 1.85 1.85 1.94 g polymer that summarizes a melt flow rate from Tables V and VI speed Y = 13.5 sec ' ¹ II 1.94 1.94 2.22 I Table V 22.2 ° C 22.2 ° C - 17.8 ° C - 28.9 ° CM kg / cm ² kg / cm ² 18.5 kg / cm ² Y = 33.8 sec "' 2.32 2.32 2.75 I sample ⁰ C Y = 67.7 sec " ¹ 1.67 2.64 2.75 3.32 M. 3.24 49.68 25.38 24.30 24.0 416 78.4 Y = 135.3 sec " ¹ 1.76 owned about 5, compared. The mechanical properties 9 Y = 338.3 sec " ¹ 1.94 Fillers, th of the graft copolymers according to the invention ■ 2.75 55.62 31.86 30.78 28.8 492 88.0 2.22 I fiberglass, has been improved much more than that 1 2.53 Polypropylene acrylic acid plug copolymer 1 H polypropylene 3.83 38.88 23.76 23.22 29.6 422 96.0 I + 25% chrysotile asbesl To illustrate the effect of i polypropylene with 4.05 65.34 37.20 36.72 35.2 580 101.0 especially chrysotile asbestos unc S 6% acrylic acid grafted, 1 + 25% chrysotile asbestos M polypropylene I + 35% chrysotile asbestos Izod- Izod impact strength, : m kg / cm secant train Warmth- B polypropylene with Notch (ft lb / in 5.4) Bending strength deformable E 6% acrylic acid grafted, tenacious module temperature b. I + 35% chrysotile asbestos speed 1 Table Vl 22.2 ° C 22.2 ° C-I7.8 ° C - 28.9 ° CM kg / cm ² kg / cm ² 18.5 kg / cm ² H sample ⁰ C n 2.92 24.30 18.36 18.36 39.1 447 101.8 ü ü 4.21 48.06 35.64 33.48 44.3 620 114.0 i 1 P polypropylene 9.18 45.90 38.88 37.20 36.2 700 102.4 I + 50% chrysotile asbestos I polypropylene with 12.42 *) 56.70 45.3 37.20 41.6 820 148.0 I 6% acrylic acid grafted, ί | + 50% chrysotile asbestos I polypropylene f |, + 20% glass fibers (3.2 mm) \ i polypropylene **) with ; 9% acrylic acid grafted. Sj + 20% glass fibers (3.2 mm) If ₁ ') support method. '5 *) Mixture G.

Example 4

The process for the preparation of product A according to Example 1 was repeated with the difference that glycidyl acrylate used instead of acrylic acid

became. The resulting modified graft copolymer had an unusually good adhesion to aluminum foil, polyester (Mylar) and nylon foil when pressure molded at 232 ° C. The results of the tests are summarized in Table VII:

Table VTI Release wedge kg / cm sample aluminum
foil Mylar 0 0 Polypropylene 2.16 to test
too tight. Polypropylene-g-glycidyl-
acrylate : <> LUPERSOI 130L) Example 5

The general procedure of Example! 1 was repeated with the difference that instead of Acrylic acid maleic anhydride was used. The maleic anhydride was added to the polypropylene and the initiator (dicumyl peroxide DCP or

The starting polypropylene had one. Melt flow index from about 0.5-

The test conditions and results are listed in Table VIII below:

Tabel VIII Peroxide- Atm. product % Maleins.- % Maleins.- % Maleins.- MFR Solution according to % Initiator anhidrid anhydride anhydride (230 ⁰ C) Graft polymers with maleic anhydride additive total grafted product 1.0 0.33 0.27 69 Xylene air 0.16 DCP 1.0 0.43 0.28 71 Xylene N ₂ 0.14 DCP 1.0 0.27 0.23 51 benzene air 0.13 DCP 0 0 0 11.5 L. benzene air 0.14 DCP 1.0 0.28 0.23 46 M. benzene N ₂ 0.14 DCP 1.0 0.23 0 1.2 N benzene air 0 1.0 0.31 0 1.1 O benzene N ₂ 0 1.0 0.38 0.24 60 P. benzene N ₂ 0.085 L. 1.0 0.33 0.21 56 Q benzene air O.O85L 3.0 0.58 0.42 56.9 R. benzene air 0.23 DCP 3.0 0.09 0.53 - S. benzene air 0.29 DCP 3.0 - - - T benzene air 0.085 L. 1.0 0.25 0.17 39.0 U benzene air 0.044L ■ \ c 0.28 0.20 57.4 V benzene air 0.084L 1.0 0.29 0.22 54.8 W. benzene air 0.089L 1.0 0.33 0.17 24.3 X benzene air O, O52L 3.0 0.33 0.20 26.2 Y benzene air 0.047L 3.0 0.41 0.29 64.2 Z benzene air 0.094L 3.0 0.40 0.26 69.8 AA benzene air 0.088L 3.0 0.35 0.20 35.9 BB benzene air 0.044L 0 - - 37.9 CC benzene air 0.1 OL 0 - - 13.5 DD benzene air 0.050L 0 - - ! 7.6 EE benzene air 0.045 L. 0 - - 35.2 FF benzene air O.O87L 1.0 0.26 0.15 33.0 GG benzene air 0.049 L. HH II YY

21

22nd

As can be seen from the table, according to the invention a good degree of conversion is obtained for maleic anhydride grafting as well as high melt flow rates.

Example 6

The product V was reinforced with an asbestos filler and in various properties with similarly reinforced Basic polypropylene compared; the results are shown in Table IX.

Table IX

l / od notch ™ higkcit

22.2 ° C l / od impact strength. cm kg / πι Sckant- <ft Ib / in 5.4) bending

mndul

/ ng- heat

strength deformation temperature b

22.2 ° C - I7.8 ° C - 28.r-C M kg / inr kg / cnv

18.5 kg / cm ^: 'C.

Polypropylene

+ 35% chrysotile asbestos polypropylene grafted with maleic anhydride + 35% chrysotile asbestos

3.94

59.94

41, (M 35.64

26.1

525

83.0

As can be seen from the table, according to the invention, improved stiffness, impact resistance and tensile strength are obtained, while the heat distortion is comparable to that of the base polypropylene.

If one replaces the filler used with TaK or glass fibers, the results are similar achieved.

The rheological properties of particularly preferred products are summarized in Tables A and B below:

Table Λ

Predominantly ethylene containing polymers

Melt index Ml

at the beginning at the end

Decrease in shape gain% Ml gain

0.05-100 0.05-1000

0.05-50 0.05-250

1-10 1-10

at least 0-0.05, preferably 0-0.1, especially 0-0.15

at least 0-0.05, preferably 0-0.1, especially 0-0.15

at least 0-0.05, preferably 0-0.1, especially 0-0.15 0-20,000, preferably 0-1000, especially 0-500

0-20,000, preferably 0-1000, especially 0-500

0-20,000, preferably 0-1000, especially 0-500

Table B.

Predominantly C ₃ to C _s containing polymers

at the beginning at the end reduction in the gain in shape

% MFR increase

0.3-0.9 3-1000, preferably 3-300, especially 3-200

0.91-5.0 5-1000, preferably 5-300, especially 5-200

5.01-10 154-1000, preferably 20-300, especially 25-250

10.1-150 15-1000, preferably 20-300, especially 25-250 at least 0.05, preferably 0.10, especially 0.15

at least 0.05, preferably 0.10, especially -0.15

at least 0.05, preferably 0.10, especially 0.15

at least 0.05, preferably 0.10 especially 0.15

1 sheet of drawings

at least 1000, preferably 1500, especially 2000

at least 500, preferably 700, especially 900

at least 300, preferably 400, especially 750

at least 50, preferably 100, especially 150

Claims (1)

Patent claims: 1, Methods of Modifying Theological or Chemical and Theological Properties a polymer that is solid at room temperature (a) Introduction of the polymer into an extruder with a movable screw displacement screw Core cross-section, which delimits a reaction zone ι ο ne, (b) generating an overpressure in the extruder during the passage of the polymer, (c) Application of heat in addition to mechanical working to turn the polymer into liquid form to convict (d) Transporting the liquid polymer into a reaction zone within the extruder, in which the polymer volume is regulated so that it is smaller than the volume of the Action zone, which creates a reduced pressure in this zone, (e) Further transport of the resulting modified polymer through the remainder of the extrusion line,