ES2335259B1 - POLYMER MATERIAL IN POWDER MODIFIED FOR USE AS AGENTECOMPATIBILIZANTE IN MIXTURES AND POLYMER COMPOSITES. - Google Patents

Abstract

Plasma modified polymer powder material for use as a compatibilizing agent in mixtures and composites polymeric

The present invention is based on a new type of compatibilizing agent based on the use of a polymer compatible with one of the components of the mixture or composite and the that surface functionalities compatible with the other components of the mixture or composite, by treatment with cold low pressure plasma. This type of compatibilizing agent is you can use in the manufacture of plastic parts by processing techniques from melting.

Description

Plasma modified polymer powder material for use as a compatibilizing agent in mixtures and composites polymeric

Technical sector

The present invention fits within the Chemical sector of the Plastics Industry and Technology of Materials, for application in Plastic Materials and Thermoplastic matrix composites with mechanical applications and structural.

State of the art

The present invention relates to a new type of polymeric compatibilizing agents, which are used as additives to increase the interfacial interaction between the components of mixtures of plastics and matrix composites polymeric containing inorganic particles. The increase in interfacial interactions produced by these new agents compatibilizers results in an improvement of mechanical properties  of mixed materials or compounds.

The compatibilizing agents are widely used in the plastics and polymeric materials industry, and they consist of macromolecules that alternate different subunits that are related to one or another of the materials to put in contact intimate in the mix or composite. These compatibilizing agents they are generally expensive for chemical synthesis techniques used, and are usually macromolecules of short chain length and, therefore, of intrinsic bad mechanical properties.

The present invention consists in using as compatibilizing agent one of the polymers to be used in the mixture or composite, in the form of micrometric powder, and modify the surface of said powders by plasma treatment to introduce functionalities compatible with the other components of the polymeric mixture, or the composite material. So, the dust modified consists of a core of the original polymer, with which it is compatible, and of a crust compatible with the other components. By reprocessing in molten this modified powder, the crust breaks and both the original polymer and the exposed polymer are exposed on the surface the modified crust, which allows the compatibility of the components of the mixture or composite.

There are patents and previous scientific articles referred to technologies for plasma treatment of powders [1,2], as well as plasma treatment of powder polymers [3,4] to introduce electric charge into the dust [5], or to increase the surface energy of the particles and allow their dissolution or suspension in polar solvents [6] and to achieve that Dust functionalization survives reprocessing and facilitates the painting of plastic parts [7]. However, the use of powders of polymer modified by plasma looking for compatibility between components of mixtures and composites for subsequent reprocessing in molten and its use as compatibilizing agents is novel and original.

Description of the invention brief description

An object of the invention is constituted by a polymeric material with use as a compatibilizing agent in mixtures and polymeric composites, hereinafter compatibilizing agent of the invention, which consists of a polymer that is compatible with one of the components of the mixture or composite, hereinafter polymer base, and to which surface functionalities are introduced that are compatible with the other components of the mixture or composite.

A particular object of the invention is constitutes that the introduction of surface functionalities in the base polymer is made on powder of said polymer with a particle diameter that can vary from a few nanometers to a few micrometers, so it will be referred to as dust microscopic. The base polymer can be the same as that component with which it is compatible before modification, or other different but from the same family of polymers and with which it shows good compatibility

Another particular object of the invention is the procedure for surface functionalization of the polymer a use as a compatibilizing agent, which is done by plasma treatment

Another particular object of the invention is the method for the compatibility of the components of the mixture or composite, which is done by melt processing of the polymer mixture containing the compatibilizing agent described previously.

Finally, object of the invention constitutes it the use of the process of the invention for the manufacture of plastic parts by any processing technique from molten, such as forming, molding, extrusion or injection, to from the polymer or composite mixture containing the agent compatibilizer described above.

Detailed description

The present invention is based on the fact that inventors have observed that it is possible to use as an agent compatibilizer in mixtures and composites a polymer that superficially modify to introduce functionalities of form that the inner part of the base polymer maintains the properties of the  original polymer, while the external part acquires new physicochemical properties depending on the introduced functionalities

The inventors have observed that the polymer modified can be reprocessed in molten state, keeping the functionalities introduced by surface treatment. In molten state, the structure of unmodified internal part and part external modified disappears, being exposed to possible interaction with other particles and polymeric fragments both parts of the modified polymer. This establishes the interaction of each part with that component of the mixture or composite with which it is compatible.

Therefore, an object of the invention is constitutes the use as a compatibilizing agent in mixtures and polymer composites of a polymer compatible with one of the components of the mixture or composite, hereinafter agent compatibilizer of the invention, and to which they are introduced surface functionalities compatible with the other components of the mixture or composite.

On the other hand, the treatment to introduce surface functionalities is especially effective when Performs on microscopic powder of the base polymer. The relationship of volume modified by the introduction of functionalities against Unmodified volume is optimal when using microscopic powder of the base polymer and the depth of the surface modification It is within the range of 1 to 10 nm.

Therefore, a particular object of the invention it is the use of the compatibilizing agent of the invention in which the introduction of surface functionalities has made on a microscopic powder of the base polymer with particles of average diameter between 10 nanometers and 10 microns

The base polymer used to form the agent compatibilizer must be compatible with one of the components of the mixture or composite, which may be the same polymer or another from his same family. Thus, for a mixture between polypropylene and polyamide, the base polymer can be the same polypropylene of the mixture, which will be modified superficially to introduce functionalities compatible with polyamide, or it may be another of the polyolefins family as a polyethylene that is compatible with the polypropylene of the mixture.

Another particular object of the invention is the use of the compatibilizing agent of the invention in which the polymer base used for its preparation is the same as any of the components of the mixture or composite.

Another particular object of the invention is the use of the compatibilizing agent of the invention in which the polymer base used for its preparation is different from the components of the mixture or composite, but from the same family and showing compatibility with them.

On the other hand, the compatibilizing agent of the invention can be prepared by a method of surface functionalization of a polymer in powder form microscopic, which consists of a plasma treatment capable of introduce functionalities on the surface of the particles keeping the original base polymer inside. Said treatment it was performed using a cold low pressure plasma, maintaining the low temperature substrate, between 25 and 200 ° C, containing sine highly energetic ions, and with the particles being supported and / or moved by gravitational effect, depending on the angle of inclination of the reactor with respect to a plane horizontal. To carry out this procedure has been used a device like the one shown in Figure 1.

Therefore, another particular object of the invention is the use of the compatibilizing agent of the invention prepared by a procedure in which the functionalization surface of the compatibilizing agent of the invention is brought to carried out by treatment with low pressure cold plasma.

On the other hand, the present invention relates to the preparation of polymeric mixtures and composites in which improves the interaction between the components through the addiction of compatibilizing agent object of the invention. The compatibilization takes place during the melt processing of the components with the compatibilizing agent added. During the melt processing the interaction of the base polymer occurs unmodified with that component with which it was compatible, and the interaction of the functionalized part with the other components with which it shows compatibility.

In the case of polymer mixtures the temperature processing must be high enough to obtain all polymeric components in molten state but sufficiently low so that its degradation does not occur, nor the desorption of functional groups introduced into the compatibilizing agent.

Therefore, another object of the invention is the procedure for the compatibility of the components of the mixture or composite, hereinafter process of the invention, which It is done by melt processing of the polymer mixture containing the compatibilizing agent described above.

       \ newpage
    

Another object of the invention is the use of the process of the invention for the manufacture of any type of material through processing techniques from molten.

Another preferred object of the invention is use of the process of the invention in the manufacture of parts of plastic.

Another preferred object of the invention is the use of the process of the invention in forming techniques, molding, extrusion or injection.

Description of the figures

Figure 1.- Diagram of a plasma reactor for surface modification of the polymer powder.

Figure 2.- Image of electron microscopy of sweeping polypropylene powder.

Figure 3.- X-ray microanalysis spectra of the treated polypropylene powder, showing the presence of functional groups containing oxygen and nitrogen.

Figure 4.- Microscopy photographs electronic scanning of cuts of a composite material of the invention consisting of polypropylene (80% by mass) with Montmorillonite (5% by mass) containing the agent as additive compatibilizer of the invention (15% by mass), melt processed In an internal mixer.

Examples of realization Example 1 Manufacture of a compatibilizing agent for composites of polypropylene with montmorillonite nanoparticles

In the first example an agent was obtained compatibilizer specific for polypropylene composites with Montmorillonite particles. Since polypropylene is a apolar and hydrophobic polymer and montmorillonite is a silicate polar and hydrophilic laminar, has been used as a base polymer for prepare the compatibilizing agent a polypropylene powder on which polar groups have been introduced by treatment with nitrogen plasma

The polypropylene powder used has a average particle diameter of 5 microns (Figure 2). Dust can be obtained directly from the polymer synthesis reactor, or be prepared from commercial pellets by grinding mechanical or forced precipitation of a solution of the Polypropylene.

The powder can be modified by treatment with plasmas of different gases such as nitrogen, oxygen and air at powers between 10 and 300 W, pressures between 0.01 mbar and 1 mbar, excited at frequencies between 13.56 MHz and 2.45 GHz. The dust is introduced into the plasma reactor, being exposed to plasma in Times between 1 second and 10 minutes. In this way they are incorporated oxygen and / or nitrogen functionalities that behave as polar groups compatible with montmorillonite.

The incorporation of oxygen functionalities and / or nitrogen on the surface can be detected with different spectroscopic techniques such as x-ray microanalysis (Figure 3) or x-ray absorption () CANES). The total nitrogen content and / or oxygen varies with the processing conditions, but is between 0.1% and 10% by mass, according to elementary analysis measures of powder.

The processability of the modified powder for produce parts from the melt was checked by processing at 190 ° C in a Brabender type double rotor internal mixer and the subsequent compression film molding. These films are used to measure the thermal and mechanical properties of compatibilizing agent of polypropylene functionalized with nitrogen and oxygen, compared to the base polypropylene without Modify. An increase in the thermal stability of the compatibilizing agent of polypropylene compared to the polymer original, being the loss temperature of 50% mass in a 439º thermogravimetic analysis for the original polypropylene and of 445º for the compatibilizing agent. It also shows a traction module increase, which is 1400 MPa in the polymer original and 1850 MPa in the compatibilizing agent object of the invention, measured according to standard UNE-EN-ISO 527.3.

       \ vskip1.000000 \ baselineskip
    

Example 2 Manufacture of a compatibilizing agent for composites of polyolefins with laminar silicate nanoparticles

In the second example the use was extended to others polymers of the same family, and other similar nanoparticles. Since all polyolefins (polyethylene, polypropylene, polybutene, etc.) are apolar and hydrophobic, the mixtures between Different polyolefins are very compatible. Similarly, others laminar silicates other than montmorillonite also show The same hydrophilic character.

It was chosen as the base polymer for the preparation of the compatibilizing agent a low polyethylene density, because it is the least expensive polyolefin. He followed preparation procedure described in Example 1, obtaining similar results, demonstrating the generality of the invention.

       \ vskip1.000000 \ baselineskip
    

Example 3 Manufacture of polypropylene composites with montmorillonite containing the compatibilizing agent of the invention

In the third example the agent was employed compatibilizer described in Example 1 for the preparation of Polypropylene composites with montmorillonite. The composites are prepared at a temperature of 190 ° C in an internal mixer of double rotor Brabender type and the subsequent molding of films by compression. Mass fractions of the different were used 80% original polypropylene components, 5% montmorillonite and 15% of the compatibilizing agent of the invention described in the Example 1. Photographs of the composite structure are shown in Figure 4.

The composite containing the agent compatibilizer was compared with a composite analog composite only 95% of original polypropylene and 5% of Montmorillonite

The use of the compatibilizing agent of the invention increases polymer-silicate interaction and induces the separation of silicate sheets, which increase their distance from 2.52 nm to 2.83 nm, as measured by diffraction of X-rays. The composite without compatibilizing agent leaves a interlaminar distance of 2.59 nm.

The increase in interaction polymer-silicate results in an improvement of mechanical properties. Thus, the traction module measured according to standard  UNE-EN-ISO 527.3, is 1400 MPa for the original polymer, 1700 MPa for the composite without agent compatibilizer, and 2030 MPa for the composite with the agent compatibilizer of the invention.

       \ vskip1.000000 \ baselineskip
    

Example 4 Manufacture of a compatibilizing agent for mixtures Polyolefin polymers with polyamides (nylon)

In the fourth example an agent has been prepared compatibilizer for mixtures of polyolefins with polyamides (nylon). Since polyolefins are apolar polymers and hydrophobic and polyamide (nylon) is polar because it contains atoms of oxygen and nitrogen in the chain, has been used as a base polymer to prepare the compatibilizing agent a polypropylene powder on which polar groups with oxygen have been introduced and nitrogen through nitrogen plasma treatments and air.

The compatibilizing agent polyolefins-polyamides is essentially the same described in Example 1.

       \ vskip1.000000 \ baselineskip
    

Example 5 Manufacture of a polymer material mixed with polypropylene polyamide containing the compatibilizing agent of the invention

In Example 5 a polymer material was prepared mixture of polypropylene with polyamide containing the agent compatibilizer of Example 4.

The method of preparation is analogous to that of Example 3, although the processing was carried out at a temperature slightly higher than that of the nylon melt, around 230ºC, so that both components are in the melt.

       \ vskip1.000000 \ baselineskip
    

Bibliography

1.- Process for surface treating / coating powder particles involves feeding powder material into dielectric barrier discharge torch assembly; in-flight modifying surface properties of particles in Torch; and collecting surface treated particles, patent WO2008014607-A1; WO2008014607-A8; US2008145553-A1.

2.- Surface treatment of powder by a atmospheric pressure plasma, patent JP6228739-A.

3.- Arpagaus , C; von Rohr , PR; Rossi , A, Short-time plasma surface modification of polymer powders in a down flowing tube reactor, SURFACE & COATINGS TECHNOLOGY vol. 200, p. 525-528 ( 2005 ).

4.- Low pressure plasma treatment of polymer powder, for automatic quasi-continuous operation, patent
DE19612270.

5.- Plasma treatment of polymer powders, patent US5439984.

6.- Surface modification of fine particles making them dispersible in fluids for coatings or sealantslby trickle flow downwards through a plasma in an evacuated low pressure chamber, patent DE19706690-A1.

7.- Plastic parts prodn. from thermoplastics involves treating the thermoplastic powder or granules with low temp. plasma before the final molding process, DE4141805 patent.

Claims (9)

1. Use as a compatibilizing agent in mixtures and polymer composites of a polymer compatible with one of the components of the mixture or composite and to which they are introduced surface functionalities compatible with the other components of the mixture or composite. 2. Use of the compatibilizing agent described in claim 1 characterized in that the introduction of the surface functionalities in the compatibilizing agent itself is carried out on a microscopic powder of the base polymer of the compatibilizing agent, with particles of average diameter between 10 nanometers and 10 microns. 3. Use of the compatibilizing agent described in claim 1 characterized in that the base polymer used for its preparation is the same as one of the components of the mixture or composite. 4. Use of the compatibilizing agent described in claim 1 characterized in that the base polymer used for its preparation is different from the components of the mixture or composite, but of the same family and showing compatibility therewith. 5. Use of the compatibilizing agent described in the preceding claims characterized in that the surface functionalization of the compatibilizing agent is carried out by treatment with low pressure cold plasma. 6. Procedure for the compatibility of the components of a mixture or composite characterized in that it is carried out by melt processing of the polymer mixture containing the compatibilizing agent described in the preceding claims. 7. Use of the procedure described in the claim 6 in the manufacture of any type of material by processing techniques from melting. 8. Use of the method according to claim 7 in the manufacture of plastic parts. 9. Use of the method according to claims 7 and 8 in forming, molding, extrusion or injection techniques.