DD275159A3 - PROCESS FOR PREPARING POLAR-MODIFIED POLYPROPYLENE - Google Patents

Abstract

The invention relates to a process for the preparation of polarmodifiziertem polypropylene. By grafting of maleic anhydride (MSA) with a mass fraction of between 0.5 and 12% to isotactic polypropylene (PP) having an average molecular weight Mw between 2.5104 and 2.5105 are using organic peroxidic and / or diazo-containing initiators, which together with the MSA are dispersed on the PP, at temperatures between 60 and 100C and while maintaining a powdery and / or koenigen and / or flaky, flaky or blätchenfoermigen consistency of the reaction medium Graftpolymerisationsprodukte having a gross mass composition corresponding to Monomerumsaetzen between 60 and 98% obtained as chemical coupler can be used in thermoplastic-glass fiber composites or as a self-adhesive polymer coating material on Metallloberflaechen.

Description

Characteristic of the known technical solutions The modification of polypropylene (PP) and propylene-ethylene copolymers by means of grafting of polar is known

functionally group-containing monomer compounds (polar monomers). using various grafting methods and technologies. To "introduce" the most suitable for increasing the adhesion

Carboxyl groups in / on the PP backbone polymer is usually acrylic acid (AS) used (DE 2426872, Dt 2455594,

US 3882194; EP 0187659, EP 0187660).

In addition to AS and other acrylic or methacrylic compounds is also MSA, in particular due to its high molecular weight

hydrophilic (polar) mass fraction, used as a grafting monomer for PP modification.

MSA can also be used analogously to AS or else methacrylic acid grafting by means of high-energy radiation

(US 3290415, US 3347692). However, these technologies have no technical interest because of their high cost.

In the same way, grafting methods of (meth) acrylic compounds are transferred to MSA, so its grafting in solution

using mostly aromatic solvents (EP 0187659, EP 0187660) or in aqueous suspension (DD 203553, EP 0001313).

These methods also require a high technical-technological and thus economic effort, especially on Reason for the costly product isolation -Abtrennung of the solvent and / or water, including drying and Recovery of the solvent and the residual monomer. These disadvantages are not exhibited by technologies based on graft modification under melting conditions. Known

is grafting of MSA to PP in the extruder in the temperature range between 180 and 260 ° C (US 4147740). The limitation of these technologies is due to the high corrosive effect of MSA on the metallic inner walls at high temperatures.

Another process principle, which does not require the use of solvents as well as water, is the

so-called gas-phase grafting of monomers below the corresponding saturation vapor pressure (elimination of a liquid phase), but which is based on polar unsaturated liquefied gases such as vinyl chloride on PP (DD 137112) or pre-oxidized PP (It 867340) and butadiene (Pegafaro, M., and Beati, E., Chim. E Ind. (Milanoj 56 (1974) 9, p.595-599) remains limited.

The obtained in this way, the aligemoinone impact-treated PP products are not for use as

chemical coupler to improve the mechanical properties while ensuring sufficient thermal stability

In glass fiber-reinforced thermoplastic composites still for self-adhesive surface coatings, especially on metals,

as known for MSA modified PP materials (FR 2572417).

Object of the invention

The aim of the invention is to economically produce polar-modified isotactic PP, which ensures by its use a high mechanical strength of the processed products.

Explanation of the essence of the invention

The invention has the object, while avoiding a high technical and technological effort, a method for the production of poler-modified PP based on the radical grafting of MSA on isotactic PP having a viscometrically determined average molecular weight M _w between 25,000 and 250,000 using organic peroxidic and or diazogruppenhaltiger initiators in the temperature range between 60 and 100 ° C, which in its use in glass fiber reinforced thermoplastic molding compositions, especially in glass fiber (GF) -PP composites, to injection molded products with an overall vei improved mechanical characteristic level or direct use as a coating material, including as Primer component, on metal surfaces to polymer topcoats with increased adhesive strength leads to develop.

According to the invention, MSA with a mass fraction of between 0.5 and 12%, based on the PP backbone polymer, is added to the graft polymer batch and, after dispersion together with the initiator or initiator mixture, while maintaining a powdery and / or grainy and / or spotty, flaky or platelet-shaped consistency of the reaction medium polymerized to a monomer conversion between 60 and 98%.

Apart from isotactic propylene homopolymers, the term PP-backbone polymers also includes isotactic propylene copolymers having a mass fraction of from 0: 0 to 5.0% of a copolymerized comonomer, in particular ethylene and butene units.

The backbone polymers have a value for fl _w between 2.5 x 10 * and 2.5 x 10 ⁵ , preferably between 1.0 x 10 ^s and 2.0 x 10 ⁶ , and are determined by appropriate measurements of the relative viscosity [η] in decalin at 135 ° C about the relationship

tn) · = 1.1 × 10 ^-4 M _w ^M

determined.

The PP-Rückgrntpolymerisate be in the form of a putver within a particle size range between 20 and 1000 μιπ

(Mass fraction of 95 to 100%), preferably between 63 and 800 μνη (mass fraction of 85 to 100%), and with an average particle diameter (C value) between 200 and 450 mm and / or as granules with a particle diameter between I.Ond and 5.0 mm, preferably between 1.5 and 4.0 mm, and / or as flakes, flakes with a length dimension between 0.1 and 0.8 mm (mass fraction of 75 to 100%) , preferably between 0.2 and 0.7 mm (mass fraction of 70 to 100%) used.

As a basis for the predominantly isotactic structural units having PP mass fraction of the used in boiling heptane

after twice 0.5 hours remaining solution residue, which is hereinafter referred to as Isotaxieindex (%).

The isotactic indices for the PP backbone polymers used are between 50 and 100%, preferably between 90 and Dij PP backbone polymers are generally prepared by known anti-oxidants and / or UV stabilizers, such as. B.

Substituted phenenes or benzene and / or Benzotriazonderivate pre-stabilized.

As peroxidic initiators, the known diacyl peroxides, such as dilauroyl and dibenzoyl peroxide (DLPO, DBPO), and Dialkyl peroxide carbonates, such as diisopropyl and di- (2-ethylhexyl) peroxydicarbonate (DIPP, DEHP), and also diazo compounds

such as 2,2'-azo-bi (isobutyronitrile).

On the dispersion of the reaction components MSA and initiators on the PP are no complicated technical and

technological requirements, since these - in general at room temperature - before heating directly in the

Reactor is carried out using the existing stirring device. Stirring time and speed are adjusted

in particular, the size and degree of filling of the reactor, which are better known in relation to its shape and equipment

Polymerization reactors or simpler ("pressure-less") agitators may correspond. Over the entire polymerization section, the reaction medium remains in a dry, powdery, or granular state

flaky to flaky or scaly state.

The polymerization of the MSA is carried out to a mass conversion between 60 and 95% and the composition of the Graft polymerization by means of a separation step (stepwise extraction with methanol - separation of not

converted MSA and the homopolymer PMSA, and xylene - separation of ungrafted PP).

Ausführungsbetsplel

A temperature-controlled and equipped with a stirrer stainless steel reactor 100 parts by mass (MT) PP with the following characteristics (PP-1):

density 0.91 g / cm ¹ WL 159000 C-value 288 pm Mass fraction of particle sizes between 200 and 800 μπ \ 92.0% between 20 and 63 pm 5.3% isotactic index 92.2% Melt index MFI ¹ JSn ⁰ 9.6 g / 10 min. (TGL 25244) Mass fraction of antioxidant 0.005% Octadecyl-3 (3,5-di-tert-butyl-4-hydroxyphenyl) proplonat

and 5MT MSA and 1 MT DBPO added and stirred at room temperature over a period of 60 min. distributed on the PP-1. Thereafter, the reactor is within 150 min. heated to a polymerization temperature (T _Pm ) of 85 ⁰ C and at constant Tp _n , a total of another 90 min. polymerized.

Subsequently, the factor is cooled, purged with nitrogen several times and at room temperature a product amount of

104.2 MT discharged from the almost Wandansatzfreien reactor.

The product obtained has sufficient fluidity, as indicated by the melt index:

2.3 g / 10 min The extraction gives the following analytical characteristics:

Unreacted MSA mass fraction, based on the total product quantity 0.55%

- Graft yield PA

iMass fraction of grafted MSA of total polymerized MSA) 72.3%

- degree of grafting PG

(Mass fraction of grafted MSA for the amount of PP submitted) 3.04%

Analogously to the example given, using two further backbone polymers (PP-2 and PP-1 in granular form having a lesser particle diameter of 1.8 mm, mass fraction below 0.8 mm diameter: between about 0.5 and 1.0%) and DLPO or DIPP as initiators MSA / PP graft polymerization products having the analytical characteristics given in Table 1.

The fluffy PP-2 has the following parameters:

density 0.912 g / cm ³ Üfw 126000 C-value 439 pm Mass fraction of particle expansion between 0.2 and 0.8 mm 96.0% isotactic index 94.9% mfi'8k ^c 5.2 g / 10 min. Masien.inteil Antioxidant 0.05%

Because of their addition to glass-fiber reinforced thermoplastics, the pol-modified PP products according to the invention cause an improvement in the most important mechanical characteristics of the GF-thermoplastic composite. The polymodified PP products used as polymer coating material for metallic surfaces have good adhesion strengths.

Table 1: Parameters for the preparation and analytical characterization of the polymodified PP products

Backbone- polymerization parameters Init. Tp _n, Pm-time PA Graft-characteristics MFlW Ser. PP MSA PG No. 100MT (MT) ( ⁰ C) (H) (%) (g / 10 min.) PP-1 (MT) 1 DBPO 85 2.5 / 1.5 72.3 (%) · 2.3 1 PP-1 6 1 DBPO 90 3.0 / 2.0 81.5 3.04 1.5 2 10 0,5DLPO 6.85 PP-1 0,5DIPP 80 2.5 / 1.0 67.5 4.8 3 granules 3 0,5DLPO 1.70 PP-2 1 DBPO 85 2.0 / 1.5 79.6 2.8 4 PP-2 5 0,5DLPO 88 3.0 / 1.5 83.6 3.30 2.0 5 10 I DBPO 7.02

Claims (1)

Process for the preparation of polymodified polypropylene based on the radical graft polymerization of maleic anhydride (MSA) on isotactic polypropylene (PP) having a viscosimetrically determined average molecular weight M _w between 25,000 and 250,000 using organic peroxidic and / or diazo group-containing initiators in the temperature range between 60 and 100 ⁰ C, while maintaining a powdery and / or körr.lgen and / or flaky, flaky or flake-like consistency of the reaction medium during the polymerization for use as a chemical Kopplsr in thermoplastic-glass fiber composites or as a self-adhesive polymer coating material on metal surfaces, characterized in that MSA with a mass fraction of between 0.5 and 12%, based on the PP backbone polymer, is added to the graft polymerization batch and, after dispersion together with the initiator or initiator mixture, up to a monomer at between 60 and 98% polymerized. Field of application of the invention The invention relates to a process for the preparation of poly-modified polypropylene based on the radical graft polymerization of maleic anhydride (MSA) on isotactic polypropylene (PP) having a viscosimetrically determined average molecular weight M _w between 25,000 and 250,000 using organic peroxidic and / or diazo-containing initiators in the Temperature range between 60 and 100 ⁰ C for use as a chemical coupler in thermoplastic-glass fiber composites or as a self-adhesive Polymerbeschic.irtungsmaterial on metal surfaces.