CZ287667B6 - Process for preparing graft olefin polymer - Google Patents

Abstract

The present process for preparing graft polymer is characterized by (a) (a) irradiating a particulate olefin polymer material at a temperature in the range of about from 10 to 85 degC with high-energy ionizing radiation to produce free radical sites, (b) treating the irradiated particulate olefin polymer material at a temperature up to about 100 degC for a period of at least about 3 minutes with about from 5 to 80 percent by weight, based on the total weight of olefin polymer and vinyl monomer used, of at least one vinyl monomer capable of being polymerized by free radicals, (c) simultaneously or successively in optional order, deactivating substantially completely all residual free radicals in the resultant grafted particulate olefin polymer material and removing any unreacted vinyl monomer from said material, whereby so polymerized olefin polymer material in the form of particles being selected from a group comprising homopolymers and random copolymers of propylene and 1-butene and impact modified copolymers of propylene and 1-butene is maintained during the above indicated steps in a substantially non-oxidizing environment at least until after the deactivation of residual free radicals has been completed.

Description

Process for producing an olefin polymer graft

Technical field

The invention relates to a process for the production of graft polyolefins, and in particular to a process for the production and polymerization of monomers at sites containing free radicals formed in olefinic polymers by high energy ionization radiation.

BACKGROUND OF THE INVENTION

The graft copolymers of polypropylene have been of particular interest for some time since they may have both the properties of the grafted polymer obtained by homopolymerization or copolymerization of the monomer or monomers and the properties of the polypropylene backbone. Some of these graft copolymers are useful as compatibilizers in the preparation of normally incompatible polymer mixtures or alloys.

The graft copolymers of polypropylene are usually produced by forming active sites on the polypropylene by irradiation with high energy ionizing radiation in the presence of a monomer capable of grafting onto these active sites or by treating said active sites with said monomer. The free radicals formed in the polypropylene polymer as a result of irradiation act as initiators for monomer polymerization as well as active grafting sites.

Most of the prior art work on radiation grafting of polymerizable monomers to polypropylene describes the application of this process to preformed, i.e. pre-made, polypropylene products such as films, fibers, woven fabrics, and the like. form as a substrate for graft copolymerization, but attention has not been focused on the possible effects that the grafting process conditions may have on those properties of the resulting graft copolymer that are important to determine its processability. For example, some of the conditions used in the prior art processes lead to drastic shortening of the length of the polypropylene chain and other crosslinking. These phenomena are often unacceptable, for example, when the graft copolymer is in the form of particles that are subjected to melt processing into shaped articles of various types.

U.S. Patent 3,058,950, relating to the preparation of N-vinyl-3-morpholinone graft copolymers on a dye-absorbing polyolefin substrate using high energy radiation, discloses that it is desirable and highly advantageous to use the polyolefin as a preformed molded article. It also states that the unformed graft copolymers obtained by the process described herein can be converted into shaped articles by any suitable means adapted for this purpose with conventional polymers. Advantageous operations of the grafting process include diluting the monomer with a solvent or dispersant, immersing the polyolefinic polymer substrate in a bath of the monomer solution or dispersion, and exposing the monomer-impregnated polyolefin substrate to a field of high energy radiation. These data indicate that one or more conditions reported to be useful and even advantageous in the graft copolymerization process may have a detrimental effect on the processability and / or usability of the graft copolymer.

According to U.S. Pat. No. 3,714,083, polypropylene powder is irradiated in air at a temperature below 5 ° C, preferably in the range of -20 to -40 ° C, and then immersed in a dilute solution of divinylbenzene monomer in a solvent such as methanol. It is reported that higher irradiation temperatures predominate homopolymer formation and that irradiation above 50 kJ / kg is undesirable due to excessive cleavage and degradation of the polypropylene, which is said to occur even at temperatures of only 5 ° C or lower.

-1 CZ 287667 B6

The effect of oxygen at various stages of the grafting process initiated by irradiation is described in various ways in the prior art. For example, in the process described in U.S. Pat. No. 3,201,336, polypropylene, preferably in the form of a preform or finished product, is subjected to high energy ionizing radiation in the presence of oxygen and then the irradiated polymer is contacted with various monomers in successive steps to form of different grafted 'branches' on the polypropylene 'stem'. It is reported that the presence of oxygen is necessary to create active centers at which grafting is to take place. During contact of the polymer with the monomer, it is preferred that the oxygen, known as the polymerization inhibitor, be absent.

US patent discloses irradiation using an inert gas atmosphere or air and water impermeable enclosure around a shaped substrate exposed to monomer to prevent degradation that may occasionally occur when irradiation is performed in the presence of air or moisture.

U.S. Pat. No. 3,314,904 discloses blending a) a graft copolymer of styrene or styrene and acrylonitrile on polyethylene or polypropylene, and b) a compatible rubber to form a "rubber plastic". The graft copolymer is produced by first "activating" the polyolefin, i.e., subjecting it to high energy ionizing radiation, and then contacting the irradiated polymer with the monomer under polymerization conditions. Linear polypropylene with a large surface area per unit weight is recommended as substrate. A typical example is the Pro-fax 6501 propylene homopolymer. To maintain the grafting capability, the irradiated polypropylene is kept in a cool and inert atmosphere before being fed into the grafting reactor. To obtain the maximum styrene or styrene / acrylonitrile content of the graft copolymer (75 to 95% by weight), the irradiated polypropylene is stirred for a long time with a dilute monomer solution or monomers at elevated temperature. The monomer conversion, i.e. the amount of monomer consumed to form the graft copolymer, is low.

Document DD 135 499 describes a method of radiation grafting. One or more monomers, normally liquid, are contacted in the vapor phase carrier gas with powdered or granulated polyolefin and then unreacted monomer is removed from the reaction zone with the carrier gas. The monomemic vapor may be introduced after or before the irradiation is complete, or the monomer vapor irradiation and introduction may be initiated simultaneously. Upon completion of the irradiation, additional monomer vapors may also be introduced. The product obtained from polypropylene and styrene / acrylonitrile vapors was a blend of polypropylene and a propylene / styrene / acrylonitrile graft copolymer, with grafting being carried out on the outer surface of the polymer granulate.

There is a need for a method of irradiating by grafting polymerizable monomers to an olefinic polymer in raw unprocessed form, i.e., in the form in which polymerization has been obtained, as such a method minimizes degradation or viscosity reduction and does not result in crosslinking of the polymer substrate. Degradation adversely affects the molecular weight of the polymer, and crosslinking adversely affects or prevents processing of the polymer in the melt. In other words, a polyolefinic graft copolymer should be obtained in which the molecular weight of the olefinic polymer chain and the melt processability of the graft copolymer are comparable to the starting olefinic polymer used for its production. Moreover, this process should not produce a graft copolymer whose melt flow index would increase during storage due to the presence of residual free radicals. Further, there is a need for a graft polymerization process that is relatively easy to carry out and effectively utilizes a grafting monomer to minimize the formation of a graft monomer homopolymer at the expense of monomer grafted polyolefin copolymer while being more economical than current processes .

There is also a need for graft copolymers of particulate polyolefins with an even distribution of graft monomer throughout the particle. Evenly distributed graft copolymers are advantageous because they provide products from graft olefinic polymers whose

The properties are not affected by the presence of a relatively large volume of substantially unreacted olefin polymer in the graft olefin polymer particles, which occurs in conventional graft polymerization processes, since the monomer essentially grafts to the surface of the polymer particles to form the graft polymer shell around the core in the graft polymer. a substantially ungrafted olefin polymer.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a process for the production of a 2 to 8 carbon olefin graft polymer in an olefin,

(a) the olefinic polymer mass in the form of particles irradiates at a temperature of 10 to 85 ° C with a high-energy ionization device to form local radicals;

(b) the irradiated particulate olefin polymer mass is heated for at least 3 minutes at a temperature of up to 100 ° C with 5 to 80% by weight, based on the total weight of the olefin polymer and the vinyl monomer used, at least one free radical polymerizable vinyl monomer;

c) simultaneously or sequentially in any order, all free radicals in the grafted olefinic polymer mass obtained are deactivated and any unreacted vinyl monomer is removed from the mass, the polymerized olefinic polymer mass in particulate form thus selected from homopolymers and random propylene copolymers; butene and impact-modified propylene-1-butene copolymers are maintained in the non-oxidizing environment during said steps at least until the inactivation of the remaining free radicals is complete.

In one embodiment of the process of the invention, the particulate mass in step b) is mixed and contacted with the monomer at a low rate at which the mass remains free-flowing.

A second preferred embodiment is the process according to the invention, wherein the monomer is allowed to act on the stirred particles in the form of a mist of liquid particles.

A third embodiment of the process according to the invention consists in treating the irradiated particulate matter with a vinyl monomer at a temperature of 10 to 50 ° C.

A fourth preferred embodiment of the invention is a process wherein step b) is carried out for at least two hours after the end of step a).

In a fifth embodiment of the process according to the invention, a particulate matter having a pore volume fraction of at least 0.04 is used in step a).

The process of the present invention is preferably carried out with a vinyl monomer selected from vinyl substituted aromatic, heterocyclic and alicyclic compounds, unsaturated aliphatic carboxylic acids and derivatives thereof, unsaturated aliphatic nitriles, vinyl esters of aromatic and saturated aliphatic carboxylic acids, divinyl compounds, and mixtures thereof.

Styrene is preferably used as monomer in the process of the invention.

In the process of the invention, the remaining free radicals are deactivated by heating the grafted olefin polymer particles to a temperature of 110 to 150 ° C.

-3GB 287667 B6

In the process of the invention, a propylene or 1-butene homopolymer is used as the particulate olefin polymer.

The invention provides a uniformly grafted olefin polymer particulate material obtained by free radical-induced grafting of at least one vinylic monomer in place of free radicals on an olefin polymer particulate material comprising a proportion of at least 0.07 pore volume, more than 40 % of the pores have a diameter greater than 1 µm, and the polymer mass further has a surface area of at least 0.1 m / g and a weight diameter particle size of about 0.4 to 7 mm. The amount of polymerized vinyl monomer or monomers grafted onto the already polymerized olefin polymer particulate is about 10 to 70%, preferably about 10 to 50% of the total weight of the grafted olefin polymer product, and the graft polymer is perfectly and uniformly distributed throughout the grafted olefin polymer particles. Polymer Clay.

All parts and percentages are by weight unless otherwise indicated.

The olefin polymer composition suitable for carrying out the process of the invention is a) a homopolymer of a linear or branched 1-olefin having 2 to 8 carbon atoms, b) a random copolymer of a linear or branched 1-olefin having 2 to 8 carbon atoms with another olefin selected from groups containing 1-olefins having 2 to 10 carbon atoms, provided that when the other olefin is ethylene, the maximum polymerized ethylene content is about 10%, preferably about 4%, when the olefin is propylene and the other olefin is 1-olefin; 4 to 10 carbon atoms, its maximum polymerized amount is about 20%, preferably about 16%, and when the olefin is ethylene and the other olefin is a 3 to 10 carbon atom 1-olefin, its maximum polymerized amount is about 10%, preferably about C) a terpolymer of a linear or branched 1-olefin having from 3 to 8 carbon atoms and two different olefins selected from the group consisting of ethylene and 1-olefins having from 4 to 8 carbon atoms; with the proviso that when one of the different olefins is ethylene, the maximum content of polymerized ethylene is about 5%, preferably about 4%, and if the olefin is 1-olefin having 4 to 8 carbon atoms, or (d) a homopolymer (a) or a random copolymer (b) whose impact strength is modified by about 10 to about 60% (1) of an ethylene-propylene rubber having an ethylene content of about 7 to about 70%, preferably about 10 to about 40%, preferably ethylene-propylene rubber having an ethylene content of about 7 to about 40%, 2) an ethylene / 1-butene (EBR) copolymer rubber having an ethylene content of about 30 to 70% (3) propylene / 1-butene (PBR) copolymer rubber with a butylene content of 30 to 70%; (4) ethylene / propylene / unconjugated diene (EPDM) copolymer with an ethylene content of 30 to 70% and a diene content of 1 to 70%; 10%, 5) ethylene / propylene / terpolymer rubber butene (EPBR) having a propylene content of 1 to 10% and a butene content of 30 to 70% or a propylene content of 30 to 70% and a butene content of 1 to 10%.

2-C8-1-olefins suitable for the preparation of the above olefinic polymer compositions include ethylene, propylene, 1-butene, isobutylene, 3-methyl-1-butene, 3,4-dimethyl-1-butene, 1- pentene, 4-methyl-1-pentene, 1-hexene, 3-methyl-1-hexene, 1-heptene and the like.

1-olefins having 3 to 10 carbon atoms which can be used to prepare the olefinic polymer compositions described above include linear and branched olefins, for example those referred to above as 1-olefins having 2 to 8 carbon atoms and having at least 3 olefins. carbon atoms.

If the olefin polymer is an ethylene homopolymer, it has a density of at least 0.91 g / m ³ , and if the olefin polymer is a copolymer of ethylene with an alpha-olefin of 3 to 10 carbon atoms, it has a density of at least 0.91 g / m ³ . Suitable copolymers of ethylene include ethylene / 1-butene, ethylene / 1-hexene and ethylene / 4-methyl-1-pentene. The ethylene copolymer may be of the HDPE or LLDPE type and the ethylene homopolymer may be of the HDPE or LDPE type. LLDPE and LDPE most often have a density of at least 0.91 g / cm ³ . HDPE is high density PE, LDPE is low density PE and LLDPE is linear low density PE.

-4GB 287667 B6

The impact-modified olefin polymer can be prepared by first polymerizing a 1 to 8 carbon atom of 1-olefin to form a homopolymer or copolymerizing it with another olefin selected from 4 to 10 carbon atoms of 1-olefin, and then the respective monomers are polymerized in the presence of said homopolymer in a reactor or series of reactors. In the practice of the process of the invention, it is also possible to use mechanical mixtures of the respective polymers prepared separately.

Homopolymers and random copolymers of ethylene, propylene and 1-butene are preferred. For ethylene, HDPE and LLDPE are preferably used.

Suitable forms of the olefinic polymer mass particles according to the invention include powder, flakes, granulate, spherical, cubic particles and the like. Spherical particle forms in which the pores occupy 0.07 volume are convenient and necessary for the preparation of the grafted olefin polymer in the form of particles.

The process of the invention produces free radicals or active sites on the olefin polymer particulate matter prior to reaction with the vinyl monomer or monomers. Irradiation in the absence of monomer is preferred, although the benefit of such a procedure varies from monomer to monomer. In the case of styrene, irradiation in the absence of monomer results in higher monomer conversion and less solvent extractable fraction, indicating a lesser extent of homopolymerization of monomeric styrene.

The olefinic polymer mass is irradiated with high energy ionizing radiation at a dose in the range of about 10 to 10 ⁵ kJ / kg / min for a period sufficient to initiate the formation of intermediates by free radicals but insufficient gelatinization of the polymer. The ionizing radiation used to form active sites in the olefin polymer mass should have sufficient energy to penetrate the mass of the irradiated olefin polymer. Energy must be sufficient to ionize the molecular structure and excite the atomic structure, but insufficient to affect the atomic nuclei. Ionizing radiation can be of any kind, but the most practical are electrons and gamma rays. Electron beams from an electron generator with an acceleration potential of 500 to 4000 kV are preferred. Satisfactory results in terms of grafting level are obtained at ionizing radiation doses of about 10 to 120 kJ / kg, preferably at least about 20 kJ / kg, generally transmitted at a rate of about 20 to 50,000 kJ / kg / min. Higher doses in the practical range are associated with a given amount of monomer with a higher grafting level and higher efficiency.

The older term "rad", which is 10 ^-2 J / kg, is usually defined as the amount of ionizing radiation that absorbs 10 ^-5 J (100 erg) energy per g of irradiated material irrespective of the radiation source. Usually, in the practice of the method of the invention, the energy absorption of ionizing radiation is measured by a known conventional disimeter in which the energy absorption sensor is a strip of fabric containing a radiation-sensitive dye. The term "rad" refers to the amount of ionizing radiation that absorbs the equivalent of 10 ^-5 J energy per g of dosimeter fabric placed on the surface of an olefinic particulate polymer mass that is irradiated in the form of a bed or layer of particles.

The irradiated olefinic polymer mass particles which are maintained in a substantially non-oxidizing atmosphere, as described in greater detail below, are treated with at least one vinylic monomer in the form of a liquid or solution, optionally diluted with a suitable diluent, preferably by adding the liquid monomer or monomer solution; / or contacting the particulate matter at a controlled rate with the particulate matter being mixed or conveyed by any suitable means of transport, and most preferably by releasing a fine mist or spraying at least one monomer onto the irradiated particulate matter while the particles are in movement relative to each other or to the point or points from which the monomer is released. The introduction of the monomer in this way facilitates its dispersion, which is advantageous in terms of the rate of grafting reaction. The particulate matter is preferably mixed

Using a fluidized bed or mechanically stirred bed, or conveying, the material is moved by a conveyor belt. The purpose is to add about 5 to 80% by weight of the vinyl monomer, based on the total weight of the olefinic polymer mass and the vinyl monomer, to the polymer mass at a controlled rate to avoid agglomeration of the particles.

Controlling the rate of monomer addition and mixing the polymer mass is particularly important for good dispersion when the volume of liquid to be added is relatively small, and to reduce heat and maintain particle flow when the volume of liquid to be added is large. In certain respects, the most preferred way of contacting the irradiated olefinic polymer mass with the monomer can be characterized as a "dry" method, since the substantially dry olefinic polymer mass particles are subjected to fine mist by the monomer at a rate at which the monomer is gradually absorbed by the particles.

The vinyl monomer, if liquid at room temperature, may be used as such or with a solvent or diluent that is inert to the polymer mass in particulate form and is not polymerizable by free radicals. If it is solid at room temperature, the vinyl monomer may be used in solution in a solvent that is inert as indicated. Mixtures of pure monomer, diluted monomer and / or dissolved by monomer may be used, especially when two or more monomers are used. In any case, whether or not the solvent or diluent is present or absent, the above range (i.e., about 5 to 80%) of the amount of vinyl monomer reacting with the olefinic polymer particulate matter, based on the monomer content.

When a monomer diluent is used, it is used to prevent excessive reduction in monomer conversion, less than about 70, preferably no more than about 50, and preferably no more than about 26% by weight of the monomer and diluent. For the same reason, it is not appropriate to use a solvent in an amount greater than that necessary to dissolve the monomer.

Solvents and diluents suitable for carrying out the process of the present invention are compounds that are, as mentioned above, inert and have a chain transfer constant of less than about 1.10 ^-3 . Suitable solvents and diluents include ketones such as acetone, alcohols such as methanol, aromatic hydrocarbons such as benzene and xylene, and cycloaliphatic hydrocarbons such as cyclohexane.

In carrying out the process of the present invention, the irradiated particulate polymeric mass is maintained in a substantially non-oxidizing atmosphere, for example under an inert gas, for as long as free radicals are present therein. The olefinic polymer mass is maintained in this atmosphere for the duration of free radical formation. This is because when exposed to an oxidizing atmosphere such as air, free radicals convert to peroxy radicals, which reduce or degrade the viscosity of the polymer mass, causing a substantial reduction in molecular weight while increasing the melt flow rate. In addition, for some monomers, such as styrene and butyl methacrylate, the presence of large amounts of air during the reaction with the irradiated polymer interferes with the grafting polymerization itself. Therefore, the irradiation of the polymer is performed in a substantially non-oxidizing atmosphere and these conditions also apply to the subsequent reaction of the irradiated particles with the vinyl monomer or monomers.

The remaining free radicals present in the olefinic polymer mass upon completion of the reaction with the monomer must be deactivated, preferably by heating the particles, before the particles are exposed to air or other oxidizing gas. Otherwise, the product would not have storage stability, i.e., the graft polymer product would degrade over time. Therefore, it is not possible to expose the grafted particles to the oxidizing environment in the reactors or in the connecting line until the free radicals have been deactivated.

In addition to the inactivation of the remaining free radicals, on the other hand, their inactivation must be prevented before grafting occurs, since free radicals are required as initiation sites for the polymerization of vinyl monomers. Since free radical deactivation occurs during heating, for example at a temperature of about 110 ° C and above,

The temperature of the graft polymerization can be carefully controlled to take advantage of the higher reactivity between the irradiated olefin polymer and the monomer, which may occur at elevated temperature, while at the same time suppressing the tendency to inactivate radicals.

In many cases, the polymerization reaction, when carried out at room temperature, is complete after about 30 to 60 minutes. In some instances, the temperature of the polymer, for example up to about 80 ° C, may result from the reaction exotherm. The use of temperatures well below room temperature during irradiation does not give rise to any advantage, and temperatures of about 10 to 85 ° C are preferred in this step. Temperatures of about 10 to 100 ° C may be used in the graft polymerization step, but a temperature of about 10 to 70 ° C, preferably about 10 to 50 ° C, is preferred.

The maximum temperature to which the olefinic particulate polymer is exposed during irradiation and grafting also depends on the melting point of the polymer mass. Since melting must be avoided, it is preferable that the polymer mass temperature in these stages be considerably, for example at least 20 ° C, lower than the melting temperature of the polymer. For example, in the case of 1-butene polymers, the irradiation and grafting temperatures should not exceed about 85 ° C.

For optimum utilization of the free radicals generated during irradiation, as well as for practical reasons, the irradiated polymer directly from the irradiation chamber is fed directly to the graft polymerization reactor. However, a residence time of about 2 to 30 minutes or even up to about 2 hours is not excluded between the irradiation step and the graft polymerization step. However, in order to avoid excessive radical depletion, the irradiated polymer should have no more than about 2 h (at room temperature). This residence time is typically about 2 to 10 minutes.

The term "substantially non-oxidizing" as used herein for the environment or atmosphere to which the irradiated olefinic polymer mass is exposed prior to the inactivation of the remaining free radicals means an environment in which the concentration of active oxygen, i.e. the concentration of oxygen in the form in which it reacts irradiated matter radicals less than about 15, preferably less than about 5, and preferably less than about 1% by volume. The most preferred concentration of active oxygen is at most 0.004% by volume. With this limitation, the non-oxidizing atmosphere can be any gas or gas mixture that is oxidatively inert to free radicals in an olefinic polymer mass, such as nitrogen, argon, helium, and carbon dioxide.

Any vinyl-free monomer capable of free radical polymerization having a vinyl radical H ₂ CR = CR-, wherein R represents hydrogen or a methyl group, may be used as a vinyl monomer according to the invention to a straight or branched aliphatic chain or to a substituted or unsubstituted aromatic , a heterocyclic or alicyclic ring of a mono- or polycyclic compound. Typical substituent groups may be alkyl, hydroxyalkyl, aryl and halogen. The vinyl monomer is usually a member of the following groups:

1. vinyl-substituted aromatic, heterocyclic or alicyclic compounds, including styrene, vinylnaphthalene, vinylpyridine, vinylpyrrolidone, vinylcarbazole and homologues thereof, for example alpha-methylstyrene, para-methylstyrene, methylchlorstyrene, methylvinylpyridine and ethylvinylpyridine;

2. Aromatic and saturated aliphatic acid vinyl esters, including vinyl formate, vinyl acetate, allyl acetate, vinyl chloroacetate, vinyl cyanoacetate, vinyl propionate and vinyl benzoate, and

3. unsaturated aliphatic nitriles, carboxylic acids and derivatives thereof, including acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, acrylic acid, acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate, butylacrylate, methacrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, butyl methacrylate, benzyl methacrylate, phenylethyl methacrylate, phenoxyethyl methacrylate, hydroxypropyl methacrylate, and maleic anhydride. Divinylic may also be used

Free radical polymerizable compounds such as butadiene and isoprene do not tend to crosslink under free radical polymerization conditions. Multiple monomers from the same or different groups may be used.

Of the various vinyl monomers that can be used, styrene, acrylonitrile, methyl methacrylate and butylarylate are preferred. According to the process of the invention, two or more monomers can be grafted onto the olefinic polymer mass at the same time, depending on the relative reactivity of the monomers used, different grafted homopolymers or copolymers are formed. Alpha-methylstyrene and maleic anhydride are grafted but not homopolymerized. Therefore, they need to be used in combination with another vinyl compound with which they copolymerize and which are more prone to free-radical-initiated polymerization, such as styrene.

The grafting level achieved by the process of the invention is dependent on several factors including the radiation dose used in the irradiation (which determines the number of free radicals produced), the amount of monomer used to react with the irradiated olefinic polymer mass, and the time and temperature of reaction with the monomer. Other factors, such as particle size and porosity of the olefinic polymer, the monomer used and the rate of feed when contacted with the polymer, also affect the grafting level, some affecting whether the grafting occurs on the surface or evenly in the polymer particle, and others affect chain length and extent formation of homopolymer. The choice of these variables is therefore made with a view to achieving the desired grafting level. A level of about 50% polymerized vinyl monomer in the graft copolymer based on the weight of the grafted olefinic polymer product is preferred. A higher radiation dose promotes a higher grafting level and grafting efficiency at a given grafting reaction temperature and monomer addition rate; a higher monomer addition promotes a higher grafting level at otherwise identical batches and reaction temperatures.

A higher level of grafting is also achieved with olefinic polymers having a higher degree of crystallinity; a value of at least about 30% as measured by X-ray diffraction is preferred. Such polymers are less subject to rapid deactivation of the free radicals present since the deactivation process is faster in the non-crystalline phase of the polymer than in its crystalline phase. The degree of crystallinity of commercial crystalline polypropylenes is about 60% or more.

The irradiated olefinic polymer mass should be maintained in contact with the monomer for at least about 3 minutes, preferably at least about 10 minutes in a semi-batch process, and preferably about 30 to about 60 minutes in a continuous process. At a given dose and monomer addition level, a longer contact time results in a higher grafting level up to a maximum contact time, which may vary at different dosages, monomers and monomer addition rates. Generally, a contact time of greater than about 3 to 4 hours is not required.

The contact time is better expressed by the monomer feed rate. In carrying out the process of the invention, the monomer feed rate may be as low as possible, and the minimum dose is dictated by the capacity of the available equipment and economic considerations. Dosages of at least about 0.1 pph / min, preferably about 1.5 to about 65 pph / min, preferably about 2.0 to about 60 pph / min (i.e., parts per hundred parts of polymer per minute) may be used.

After reaction of the olefinic polymer mass with the monomer, the grafted polymer obtained, still maintained in a substantially non-oxidizing environment, is subjected to a treatment, preferably by heating, resulting in virtually complete deactivation of any free radicals remaining therein. This substantially eliminates the possibility of peroxy radicals in the graft copolymer upon exposure to air. These radicals could cause a decrease in viscosity or degradation of the polymer. In most cases, the deactivation temperature is at least about 110, preferably at least about 120 ° C. High temperatures of up to about 250 ° C may be used, but it is preferred to select the deactivation temperature to be below the melting point of the graft polymer, generally at most about 150 ° C for graft polypropylene copolymers and at most about 100 ° C for graft polybutene copolymers.

-8EN 287667 B6

Thus, the preferred deactivation temperature is about 120 to 150 ° C for the polypropylene graft copolymers and about 85 to 100 ° C for the polybutene graft copolymers. Typically, heating to a deactivation temperature for at least about 20 minutes is sufficient. The free radical deactivation can also be carried out using an additive such as methyl mercaptan, which acts as a free radical scavenger.

Any unreacted vinyl monomer is removed from the graft copolymer before, during or after the deactivation of the radicals. When the removal is carried out before or during inactivation, a substantially non-oxidizing environment is maintained. In one preferred embodiment, the graft copolymer monomer is stripped in a stream of nitrogen or other inert gas at a selected deactivation temperature, for example, about 140 ° C for polypropylene graft copolymers. In a continuous process, the graft copolymer can be fed into the fluidized bed and deactivated by heating to a selected temperature and the outlet gas condensed to remove the monomer carried in the nitrogen stream.

The grafted olefin polymer composition of the invention is prepared by grafting at least one free radical-initiated vinyl monomer to free radical sites on the crude olefin polymer composition in the state as it has been polymerized, in the form of particles having a mass median diameter of about 0.4 to 7 mm, a surface area of at least 0.1 m ² / g pore volume fraction of at least about 0.07, i. wherein 7% by volume is pores, more than 40% of the pores in the particle have a diameter greater than 1 µm. Preferably, the diameter greater than 1 µm has more than 50% of the pores in the particle, and preferably more than 90% of the pores in the particle. The pore volume fraction is preferably at least 0.12; preferably at least 0.20. Both the pore volume of at least about 0.07 and the pore diameter, wherein the diameter greater than 1 µm have more than 40% of the pores in the particle, are critical to the preparation of the grafted olefin polymer composition of the invention. Crude olefin polymer compositions with this combination of pore volume and pore diameter were not commercially available until recently. In such an olefin polymer mass, the grafting and polymerization of the vinyl monomer takes place both within the mass of the particles and on their outer surface, thereby producing a substantially uniform distribution of the grafted polymer within the olefin polymer particle. Commercially available ethylene and propylene particulate polymers without these characteristics, although having a reasonably large surface area and high porosity, do not provide graft copolymers with internal grafting or even graft copolymer distribution because they lack the required pore diameter and large pore volume required for producing a grafted olefin polymer product of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The grafted olefinic polymer product of the invention is described with reference to the accompanying drawings, in which:

Giant. 1 is a 125x magnified phase contrast microtome photomicrograph of a cross-section of a uniformly grafted crude homopolymic propylene product of Example 8, containing the light regions covered by Examples 1, 2 and 3 which are rich in homopolymic propylene mass grafted with polystyrene throughout the particle.

Giant. 2 is a 125x magnified phase contrast microtome micrograph of a cross-section of a graft of a conventional homopolymic propylene product of Example 38, containing the light regions covered by Examples 4, 5 and 6 that are rich in homopolymic propylene mass grafted with polystyrene substantially at the periphery of the particle core, with the sheath formed around the core of the propylene polymer particle. The dark areas referred to in Example 7 consist of a substantially ungrafted propylene homopolymer.

-9EN 287667 B6

In the figures, microstructural differences can be observed between the propylene graft homopolymer of the invention and the propylene graft homopolymer produced by grafting onto a conventional low pore diameter propylene homopolymer particle and low porosity. In Fig. 1, which shows a graft propylene homopolymer particle according to the invention, i.e. a particle of the product of Example 8, regions of high concentration of polystyrene, i.e. polystyrene grafted to a propylene homopolymer, are visible not only on the particle surface but deep throughout its interior. The presence of polystyrene in these regions was confirmed by a Fierier transform IR microscope. In the particle of the product of Example 38, prepared from a typical commercially available propylene homopolymer in the form of particles shown in Figure 2, the high polystyrene content is substantially limited to areas around the outer surface of the particle. If styrene occurs at all within the particle, its content in the interior of the particle is low, indicating a substantially ungrafted homopolymic propylene core. This was confirmed by IR microscopy as the microscope showed no polystyrene content inside the particle.

In addition to irradiation, free radical sites or active sites can be formed in the particulate olefinic polymer mass by treatment with an organic compound which is a free radical polymerization initiator and has a half-life at a temperature of about 1 to 240, preferably about 5 to 100 and preferably about 10 to 40 min. A preferred group of initiators are organic peroxides, especially those which form alkoxy radicals. Azo compounds such as azobisisibutyronitrile may also be used. Inorganic peroxides are also within the broad concept of the invention but are not preferred. Two or more initiators with the same or different half-lives may be used.

The process of the invention can be used to produce graft olefin polymers from any olefinic polymer particulate material having a pore volume fraction of at least 0.04. However, it is preferred to perform grafting on olefinic polymers having a pore volume fraction of at least 0.07, in which more than 40% of the pores have a diameter greater than 1 µm. Preferably, the olefinic polymer used according to the invention has a pore volume fraction of at least about 0.20 and more than 90% of the pores have a diameter of greater than 1 µm, a surface area of at least 0.1 m ² / g and a weight median diameter of about 0, 4 to 7 mm.

DETAILED DESCRIPTION OF THE INVENTION

The following are examples of illumination of the graft olefinic polymer of the present invention and a process for its production.

When the molded polymer or copolymer is mentioned in the examples, it was made by injecting the particulate product in two stages under the following conditions: Nozzle temperature 232 ° C, cylinder temperature about 230 ° C, injection time in first stage 10 s, injection time in second stage 10 s, water inlet temperature 66 ° C, cooling time 20 to 30 s, mold opening time 2 s.

The pore volume fractions were determined by the mercury porosimetry method, which measures the volume of mercury absorbed by the particles. The volume of mercury absorbed corresponds to the pore volume.

The surface area was measured by the BET method.

Example 1

This example illustrates the graft olefin polymer of the present invention and a process for its production.

a) Polymer irradiation

A finely divided porous propylene homopolymer, commercially available from HIMONT Italia S.p.A. under the designation LBD-520A, having the following characteristics: nominal speed

Melt flow (ASTM D 1238-82, condition L) 22.7 dg / min, intrinsic viscosity (JH Elliott et al., J. Applied Polymer Sci. 14, 2947-2996, 1970 - polymer dissolved in decahydronaphthalene at 135 ° C) 1.89 dl / g, extractability in methylene chloride 2.0% by weight, BET 0.38 m ² / g, weight average diameter 1.88 mm and pore volume fraction (mercury method) porosimetry) 0.45. More than 90% of the pores in the porous particles have a diameter greater than 1 µm.

270 g of substantially oxygen-free polypropylene forms a powder bed of approximately 2 cm in thickness on a movable conveyor, which is passed through an electron beam generated by a Van de Graaff 2 MeV generator operating at 312 μΑ beam current with the conveyor. The conveyor speed is adjusted to absorb a surface dose of 40 kJ / kg delivered at a rate of about 300 kJ / kg / min. The atmosphere or atmosphere in the closed irradiation chamber is substantially nitrogen gas and the active oxygen content is maintained below 0.004% by volume. The chamber has a room temperature of about 23 ° C.

b) Reaction with grafting monomer

The irradiated polypropylene is fed from the irradiation chamber to a grafting polymerization reactor at room temperature, i.e. 23 ° C. In the reactor, 30 g of liquid monomeric styrene (10% styrene, based on the total weight of styrene and polypropylene) are mixed and sprayed, added to the stirred powder at a rate of about 60 ml / min. A nitrogen atmosphere is maintained in both the reactor and the transport system for conveying the irradiated particles from the irradiation chamber to the polymerization reactor so that the amount of active oxygen is less than 0.004% by volume. The residence time between the electron beam treatment of the polypropylene and the reaction with styrene monomer is about 2 minutes.

The temperature of the powder when reacted with the monomer increases by about 20 ° C due to the reaction exotherm. The styrene / polypropylene mixture was stirred for 30 min.

c) Inactivation of the remaining free radicals

Upon completion of the grafting reaction, the reactor is heated to 140 ° C and maintained at this temperature for 30 minutes with a stream of heated nitrogen obtained by means of an electric heating mantle. The nitrogen flow is high enough to minimize the heating time by sufficient heat transfer and to ensure sufficient mass transfer to remove any unreacted monomeric styrene. The free-flowing solid product remaining in the reactor was approximately 295 g. The polystyrene content was 8.4% by infrared analysis. The unreacted monomeric styrene content was less than 25 ppm. An infrared analysis of the insoluble fraction of the product remaining after Soxhlet extraction with methylene chloride at 65 ° C for 2 hours revealed a polystyrene content of graft polypropylene of 8.8% by weight. The solubility of the product in methylene chloride was 2.1% by weight, the soluble portion of the extraction contained low molecular weight polypropylene grafted with polystyrene, and a styrene homopolymer. The total content of polystyrene in the proportion soluble in methylene chloride was 11.3% by weight, with the weight balance showing that only a small part of this amount is a styrene homopolymer.

The melt flow rate (MFR) of the crude graft copolymer was 324 dg / min. Both the MFR of the graft copolymer and the above-mentioned MFR of the starting raw polypropylene were measured on the molten polymer. To measure the MFR of these polymers and the other products described in the following examples, the procedure of ASTM D 1238, condition L was used.

The results of the tests carried out on the grafted polymer to determine its strength are shown in Table I, together with the results of the tests carried out: (a) on a physical blend of polypropylene

And (b) on polypropylene used to produce both graft copolymers and blends.

The flexural modulus and flexural strength in this and other examples were measured according to ASTM D 790.

Table I

PP-PS graft copolymer (8.4% WG) PP-PS mixture (8.4% PS) PP bending module as 1% sec, MPA 1 841 1 579 1 393 bending strength, MPa 57 52 47

* PP - polypropylene, PS - polystyrene

MFR 146 dg / min on molten polymer

Product stability

The polypropylene grafted with 10% polystyrene produced as described above, but using a styrene addition rate of 50 ml / min and a mixing time of 60 min, has an MFR measured on the particles just after production of 38 dg / min, 1 week 37.5 dg / min and after 1 month 42.3 dg / min. On the other hand, the 9.6% graft copolymer produced by the process described, but with the addition of styrene at 44 ml / min in step b) and the deactivation step c) is omitted (the reactor is purged with nitrogen at room temperature and left (reactor). is purged with nitrogen at room temperature and left at this temperature for 60 min to remove any unreacted styrene), has a MFR of 119 dg / min, after 1 week 620 dg / min, and after 1 month 871 dg / min, degradation of the polymer, continued from the time of its formation.

Also, the difference between the MFR of the grafted polypropylene and the MFR of the starting polypropylene is considerably lower in the case of the graft copolymers produced by the process of the invention than in the case of the graft copolymers produced by a process in which the remaining free radicals are not deactivated.

Examples 2 to 5

The procedure and additives of Example 1 are used, but the amount of styrene is varied as shown in Table II, i.e. 240 g of polypropylene and 60 g of styrene in Example 2, 180 g of polypropylene and 120 g of styrene in Example 3 are used. 4,150 g of polypropylene and 150 g of styrene, and in Example 5, 120 g of polypropylene and 280 g of styrene, and the styrene addition rate in step b) is usually from 40 to 60 ml / min.

The results of the analytical measurements and tests of the properties of all the styrene-grafted polypropylene copolymers obtained are shown in Table II together with the results obtained with physical blends of polypropylene (the same polypropylene with which the graft copolymers were produced) and polystyrene with substantially the same polystyrene content. The tensile and tensile strengths listed in Table II were measured, as in all other examples, according to ASTM D 638.

- 12GB 287667 B6

Examples 6 and 7

The procedure and additives of Example 4 are used, but the dose in step a) in Example 6 is 10 kJ / kg and the Example Ί 120 kJ / kg, the monomer addition rate in step b) is 55 to 65 ml / min and

200 g polypropylene and 200 g styrene. In Example 6, it is irradiated at a rate of 75 kJ / kg / min. The results of the analytical measurements and performance tests performed on the two styrene grafted polypropylene copolymers obtained are shown in Table II.

Table II

Př-2 Ex 3 4 Ex 5 Ex 6 Ex 7 PP-PS PP-PS PP-PS 100% PP ’ % styrene addition wt. 20 May 40 50 70 50 50 % PS in the mixture 16.6 37.3 47.0 % PS after grafting v pev. IR 16.6 34.6 37.3 47.0 30.5 40.1 % Of PS in share, not res. in CH ₂ Cl ₂ - IR 17.8 34.2 38.6 44.3 31.2 40.1 % Of PS in the share of CH ₂ Cl ₂ -, IR 18.7 25.2 38.7 47.9 25.1 41.3 proportions % in CH ₂ Cl ₂ wt. 2.1 2.1 2.2 2.2 2.1 2,0 MFR (dg / min) 30 2.6 2.3 0.6 4.4 20.6 24 27 Mar: 21 tensile strength, MPa 35.9 32.7 35.5 39.0 26.9 32.1 28.9 31.5 32.0 elongation,% 3.4 2.1 2.2 3.6 1.6 5.5 3.2 2.5 11.9 bending modulus as 1% sec, MPa 1 979 2 165 2 199 2 144 1 799 1 898 2 32J 1 393 bending strength, MPa 62.1 66.9 66.2 62.7 68.3 53.1 57.2 50.3 56.5 46.9

* polypropylene for the production of graft copolymers and mixtures ”blend of polypropylene (PP) and polystyrene (PS)

Examples 8 to 11

The procedure and additives of Example 1 are used, using 210 g of polypropylene and 90 g of styrene, the styrene (liquid) in Examples 9, 10 and 11 being diluted with varying amounts of methanol and the astyrene diluted with methanol is sprayed onto the polymer in Examples 9 50 ml / min, for example 10 about 40 ml / min and for example 11 about 57 ml / min. The grafting level and the melt flow rates achieved are shown in Table III. The product of Example 8 contained 26.4% by weight of polystyrene by IR analysis of the solid graft copolymer obtained and 53% by weight of polystyrene by IR analysis of the dichloromethane-soluble fraction.

Table III

Ex · methanol, g % polystyrene, wt. IR fraction insol. in CH2Cl2 MFR ', dg / min 8 0 22.8 5.7 9 45 27.1 15.7 10 90 19.6 22.8 11 180 11.0 55.9

* measured on particles

-13GB 287667 B6

Control experiment

This experiment demonstrates the advantage of irradiating the polymer mass before exposure to the vinyl monomer.

31.5 g of the same polypropylene as in Example 1 is placed in a flask which is stopped and purged for 30 min with a stream of nitrogen. 13.5 g of liquid styrene are then injected into the flask and the polypropylene and styrene are stirred for 5 min. The mixture is irradiated with a 2 MeV electron beam to a dose of 40 kJ / kg (irradiation rate of about 300 kJ / kg / min). The mixture was stirred for 30 min, then cooled in an oil bath at 140 ° C for 30 min and dried in a vacuum oven at 80 ° C for 2 h.

According to IR analysis, the polystyrene content of the product obtained is only 6.2% by weight. The proportion insoluble in methylene chloride is 5.2% of graft polystyrene. The methylene chloride soluble fraction contained 49% by weight of polystyrene. The soluble fraction was 3.6% by weight of the product. The mass balance shows that a styrene homopolymer has formed. The melt flow rate of the graft copolymer is 500 dg / min.

Control experiments 2 to 4

A procedure and additives similar to Example 8 were used, but air was used instead of nitrogen as shown in Table IV and step c) was omitted in Experiment 3. The results are shown in Table IV.

Table IV

try air % polystyrene, wt. IR fraction insol. in CH2Cl2 MFR, dg / min 2 step a) 25.1 123 3 step b) * 0 > 1000 4 step c) 27.0 471

* step c) omitted as measured on particles

Example 12

A procedure and additives similar to Example 1 are used, but polypropylene having a melt flow rate of 6.9 dg / min, a pore volume ratio of 0.33, a surface area (BET) of 0.34 m ² / gas of more than 90% is used. pore diameters greater than 1 µm (LBD 406A, commercially available from HIMONT Italia SpA), 200 g polypropylene and 200 g styrene, and a styrene addition rate of about 50 ml / min. The resulting solid graft copolymer product contains 41.2% by weight of polystyrene, as determined by the IR product, and has a melt flow rate of 1.2 dg / min, as measured on the molded part.

-14GB 287667 B6

Examples 13 to 16

A procedure and additives similar to Example 1 were used, but using polypropylene Pro-fax 6801 having an intrinsic viscosity of 5.04 dl / g, a melt flow rate of 0.3 dg / min, a surface area (BET) of 2.5 m7g, a pore volume (mercury porosimetry) of 0.15, a weight median diameter (Dw) of 0.21 mm, a bulk density of 0.53 g / ml, and a solubility in methylene chloride of 0.5% by weight. None of the pores in the particles had a diameter greater than 1 µm. The properties of the polypropylene were determined by the same procedures as for the polypropylene of Example 1.

The reaction time in Example 13 is 60 min, the total weight of polypropylene and styrene in Examples 14, 15 and 16 400 g and the styrene addition rate in Example 13 is about 50 ml / min and in Examples 14, 15 and 16 about 40 to 60 ml / min.

Analytical results for all four polystyrene-grafted propylene copolymers are shown in Table V. Morphological studies show that the graft copolymer is concentrated at the outer surface of the particles and forms the graft copolymer shell particles around the polypropylene core.

Table V

Ex 13 Ex 14 Ex 15 ex 16 % styrene, wt. 10 30 50 70 polystyrene, wt%, IR solid graft product 8.1 23.9 49.3 48.1 polystyrene,% by weight, IR fraction insol. in CH ₂ CI ₂ 8.0 24.2 49.3 49.3 polystyrene wt.%, the proportion of soluble IR in CH ₂ C1 ₂ 60 72 79 90 proportions in CH ₂ C1 _2, wt.% 0.1 0.4 0.5 0.5 MFR, dg / min * 0.33 0.27 0.10 0.02

* measured on a molded part

Examples 17 to 20

A procedure and additives similar to Example 1 were used, but n-butyl methacrylate (BMA) was used instead of styrene, using 270 g of polypropylene and 30 g of BMA in Example 17, 210 g of polypropylene in Example 18 and 90 g of BMA. of Example 19 150 g of polypropylene and 150 g of BMA and in Example 20 of 90 g of polypropylene and 210 g of BMA. The test results are shown in Table VI.

- 15GB 287667 B6

Table VI

Ex 17 Ex 18 Ex 19 eg 20 % BMA, wt. 10 30 50 70 poly (BMA),% by weight, IR solid graft product 8.2 26.8 46.9 68.3 poly (BMA),% by weight, IR fraction insol. in CH ₂ C1 ₂ 7.0 29.1 68.0 poly (BMA), wt.%, the proportion of soluble IR in CH ₂ C1 ₂ 37.0 28.2 96 65.1 proportions in CH ₂ C1 _2, wt.% 2,0 2.3 1,8 2,0 MFR, dg / min ' 320 58 27 Mar: 0.8 tensile strength, MPa 29.6 22.2 15.6 11.7 elongation,% 9.7 16.3 25.1 25.2 elongation at break, mm (ASTM D-638) rapid breakage 72 292 242 bending modulus as 1% sec, MPa 1 310 910 600 434 bending strength, MPa 42.7 29.6 19.3 13.1

* measured on a molded part

Examples 21 to 24

The procedure and additives were used as in Examples 13 to 16, but n-butyl methacrylate (BMA) was used instead of styrene and added at a rate of about 40 to 60 ml / min.

The test results for all four propylene copolymers grafted with poly (n-butyl methacrylate) are shown in Table VII. Morphological studies show that the graft polymer formation was concentrated at the outer surface of the particles, so that the graft copolymer shell was formed around the polypropylene core of the particle.

Table VII

Ex 21 Ex 22 Ex 23 24 % BMA, wt. 10 30 50 70 poly (BMA),% by weight, IR solid graft product 7.9 27.8 46.6 63.5 poly (BMA),% by weight, IR fraction insol. in CH ₂ C1 ₂ 9.9 28.8 47.7 68.0 poly (BMA), wt.%, the proportion of soluble IR in CH ₂ C1 ₂ 100 ALIGN! 80 76 79.5 proportions in CH ₂ C1 _2, wt.% 0.3 0.6 0.7 0.9 MFR, dg / min ' 10.3 5.1

measured on the molded part

Examples 25 to 27

The procedure and additives were used as in Example 1, but n-butyl acrylate was used instead of styrene, with 360 g of polypropylene and 40 g of n-butyl acrylate in Example 25, in Example 26

- 16GB 287667 B6

312 g of polypropylene and 88 g of n-butyl acrylate and in Example 27 200 g of polypropylene and 200 g of n-butyl acrylate and polypropylene (LBD-406A, commercially available from HIMONT Italia SpA) have a nominal melt flow rate of 6.9 dg / min. 4 dl / g, solubility in methylene chloride 1,4% w / w, surface area (BET) 0,34 m ² / g, pore volume (mercury porosimetry) 0,33 and more than 90% of pores with a diameter greater than 1 pm . The results of the tests and measurements performed on the obtained propylene polymers grafted with n-butyl acrylate are shown in Table VIII.

Table VIII

Ex 25 ex 26 Ex 27 % n-butyl acrylate, wt. 10 22nd 50 poly (n-butyl acrylate),% by weight, grafted on a solid product, from the mass balance 8.8 21.2 48.1 MFR, dg / min ' 60.5 11.0 6.8 bending modulus as 1% sec, MPa 1 499 1 027 503 bending strength, MPa 46.2 37.9 14.5 tensile strength, MPa 31.0 24.1 11.0 elongation,% 9.9 12.9 19.0 Izod notch toughness at 23 ° C, J / m (ASTM D-256) 69.4 294 without breaking

'Measured on the molded part

Examples 28 to 30

Using the procedure and additives of Example 1, various monomers are grafted onto polypropylene under the following conditions:

Example 28: 360 g of Pro-Fax 6501 polypropylene with a melt flow rate of 2.6 dg / min. 40 g of benzyl methacrylate is added to the polypropylene at a rate of about 10 ml / min and then stirred for 60 minutes. The particles are then removed from the polymerization reactor and left in a vacuum oven at room temperature for 15 minutes to remove any entrapped air. The temperature is raised to 140 ° C and held at this temperature for 60 min. The product weighs approximately 384 g. Sexhlet extraction is performed with methyl ethyl ketone (MEK) at 75 ° C.

Examples 29 and 30: The procedure is analogous to Example 28, but the monomer is phenylethyl methacrylate, added at a rate of 12 ml / min (Example 29), respectively. phenoxyethyl methacrylate added at a rate of 6 ml / min (Example 30).

The grafting level determined by IR analysis of the MEK insoluble product fraction and the melt flow rate of the products is shown in Table IX.

Table IX

Ex · monomer grafted monomer,% by weight, IR fraction insol. v MEK MFR dg / min 28 benzyl methacrylate 7 40 29 phenylethylmethacrylát 7 52 30 phenoxyethyl methacrylate 6 18

- 17GB 287667 B6

Examples 31 and 32

These examples illustrate the preparation of a propylene grafted styrene-maleic anhydride copolymer.

The procedure and additives of Example 1 are used, but the MFR of the polypropylene is 44.7 dg / min and its intrinsic viscosity is 1.51 dl / g. In Example 31, a liquid mixture of 60 g styrene, 60 g maleic anhydride and 78 g acetone is sprayed onto 280 g of irradiated polypropylene, and in Example 32 a liquid mixture of 100 g styrene, 100 g maleic anhydride and 78 g acetone is added to 200 g polypropylene. maleic anhydride is alternately a mixture of methanol and toluene with acetone. The results are shown in Table X.

Table X

ex 31 32 % monomer (styrene + maleic anhydride), wt. 30 50 grafted terpolymer; styrene, wt%, of the IR graft product 14.5 22.3 maleic anhydride, wt%, IR of the graft product 14.5 23.8 MFR, dg / min * 5.0 0.4 HDT, 455 kPa, ° C ” 114 131 HDT, 1820 kPa, ° C 58 67 bending modulus as 1% sec, MPa 1586 2 110 bending strength, MPa 47.6 53.1 tensile strength, MPa 22.7 19.1

* measured on molded part ** ASTM D-648

Example 33

The process and additives of Example 1 are used, wherein a liquid mixture of 60 g styrene and 60 g alphamethylstyrene is sprayed onto 280 g of irradiated polypropylene at a rate of about 48 ml / min and the polypropylene has an MFR of 45 dg / min and a bulk density of 0.36 g / ml. The grafting level (total styrene plus alpha-methylstyrene) is about 21%. The ratio of styrene to alpha-methylstyrene in the graft copolymer is about 1: 1.

Examples 34 to 37

The procedure and additives of Example 1 were used, replacing the propylene homopolymer with a random copolymer of ethylene and propylene with an ethylene content of about 4.0% (Examples 34 and 35) and chemically EPR-modified polypropylene with a polypropylene content of about 88% and an EPR content of about 12%. % and with an ethylene content of about 8% (Examples 36 and 37) and in Examples 35 and 37, the styrene was replaced with n-butyl methacrylate. The polymer and each monomer are used in an amount of 200 g (50% by weight of the monomer) and the monomer is added at a rate of about 45 ml / min. The irradiation dose is 10 kJ / kg at a rate of about 75 JJ / kg / min.

The test results of all four graft copolymers obtained are shown in Table XI, together with the results obtained for the physical blends of these propylene starting polymers with the same amount of polystyrene or poly (n-butyl methacrylate) as contained in the graft copolymers.

-18GB 287667 B6

Table XI

Example 34 35 ex 36 eg 37 PP-PS PP-poly PP-PS ’ PP-poly (BMA) ” polystyrene or poles (BMA) ',% by weight, of IR solids, polymer 23.2 28.5 23.9 34.3 IR fraction insol. CH ₂ Cl ₂ , 21.0 24.9 26.0 26.7 IR fraction in CH ₂ C1 ₂ 31.4 12.4 40.1 34.9 proportions in CH ₂ C1 _2, wt.% 1.6 1.7 1.4 1.5 % polystyrene or poles (BMA) in the mixture; 23.2 28.5 23.9 34.3 5.2 9.1 0.68 12.7 16.6 62 7.6 37 bending modulus as 1% sec, MPa 1 613 820 1 772 869 1 455 689 1 606 558 bending strength, MPa 53.1 26.9 54.5 26.9 48.3 24.8 51.0 18.6 notch. houž. Isor at 23 ° C, J / m, ASTM D-256 26.7 16.0 90.8 64.1 26.7 16.0 42.7 245.5

* eg 34 and 36 PS, eg 35 and 37 poly (BMA), eg PP from 34 and 35, *** eg PP from 36 and 37

Example 38

The procedure described in Example 15 is repeated, but the polypropylene Pro-Fax 6801 used has an intrinsic viscosity of 4.89 dl / g, a melt flow rate of 0.2 dg / min, a surface area of 0.14 m ² / g, a pore volume fraction ( mercury porosimetry) of 0.04, a weight mean diameter of 0.36 mm, a bulk density of 0.55 g / ml, and a solubility in methylene chloride of 0.4% by weight. No pores greater than 1 µm in diameter are present. 150 g of polypropylene and 150 g of styrene are used. According to IR analysis of the graft copolymer obtained, the amount of polystyrene is 23.2% by weight and according to IR analysis the proportion insoluble in methylene chloride is 26.0% by weight.

Morphological studies show that the graft polymer formation centered around the outer edges of the particles, so that the graft polymer shell was formed around the core of the polypropylene particle (Fig. 2).

Claims (10)

PATENT CLAIMS CLAIMS 1. A process for the production of a 2 to 8 carbon olefin graft polymer comprising: a) the olefinic polymer mass in the form of particles irradiates with high energy ionization radiation at a temperature of 10 to 85 ° C to produce local radicals, b) the irradiated particulate olefinic polymer mass is heated for at least 3 minutes at a temperature of up to 100 ° C with 5 to 80% by weight based on the total weight of the olefinic polymer and the vinyl monomer used, at least one free radical polymerizable vinyl monomer; c) simultaneously or sequentially in any order, all free radicals in the grafted olefinic polymer mass obtained are deactivated and any unreacted vinyl monomer is removed from the mass, the polymerized olefinic polymer mass in the form of particles selected from homopolymers and random copolymers of propylene and 1-butene and impact-modified propylene-1-butene copolymers are maintained in said non-oxidizing environment during said steps at least until the deactivation of the remaining free radicals is complete. -19GB 287667 B6 The process according to claim 1, characterized in that the particulate mass in step b) is mixed and contacted with the monomer at a low rate at which the mass remains free-flowing. 3. A process according to claim 2 wherein the monomer is allowed to act on the stirred particles in the form of a mist of liquid particles. The method according to claim 1, characterized in that the irradiated particulate matter is treated with vinyl monomer at a temperature of 10 to 50 ° C. The method of claim 1, wherein step b) is carried out for at least two hours after the end of step a). Method according to claim 1, characterized in that in step a) a particulate matter with a pore volume fraction of at least 0.04 is used. 7. The process of claim 1 wherein the vinyl monomer is selected from the group consisting of vinyl substituted aromatic, heterocyclic and alicyclic compounds, unsaturated aliphatic carboxylic acids and derivatives thereof, unsaturated aliphatic nitriles, vinyl esters of aromatic and saturated aliphatic carboxylic acids. , divinyl compounds and mixtures thereof. 8. The process according to claim 7, wherein styrene is used as the monomer. 9. The process of claim 1 wherein the residual free radicals are deactivated by heating the graft olefin polymer particles to a temperature of 110-150 [deg.] C. 10. The process of claim 1 wherein the olefin polymer in particulate form is a propylene or 1-butene homopolymer.