DD252383A1 - HIGH-LIQUID PVC MOLDING - Google Patents

Abstract

Highly flowable PVC molding compositions are prepared by adding flow improvers based on VC / EVAC graft polymerization products prepared by grafting vinyl chloride (VC) onto EVAC waxes having the composition 25 to 40% by weight of vinyl acetate / 75 to 60% by weight of ethylene units and having an average molecular weight Mn of between 1,000 and 5,000, generally in an aqueous suspension, which may further contain a known (PVC) crosslinking agent, to a PVC mass gain in the range of 0.8 to 3.0 while maintaining of VC pressures below the respective VC saturation pressure at temperatures between 325 K and 345 K, in an amount of between 0.5 and 5.0%, based on the total molding composition, to polyvinyl chloride (PVC) with Fikent's K values of 60, preferably suspension PVC with K values between 50 and 59. By adding the flow improvers, neither the mechanical nor thermal characteristics of the PVC are adversely affected. The impact properties are increased gradually and the fluidity values (melt indices and injection molding flow rates) are increased above average.

Description

Field of application of the invention

The invention relates to highly flowable PVC molding compositions based on polyvinyl chloride (PVC) with Fikentscher K values between 50 and 60, which by grafting of vinyl chloride (VC) to ethylene-vinyl acetate copolymers (EVAC) up to a PVC mass increase in the range from 0.8 to 3.0 at monomer pressures ρ below the corresponding monomer saturation pressure p _s in the temperature range between 325 K and 345 K, VC / EVAC graft polymerization products obtained in an amount between 0.6 and 5% by mass are added as flow improvers.

Characteristic of the known technical solutions

Various PVC flow improvers are known which are obtained by grafting VC or other vinyl monomers such. B.

Methyl methacrylate (MMA), on elastomers or directly on PVC.

In addition to the incorporation of from 1 to 5% by mass of poly (meth) acrylates, in particular PMMA or MMA acrylate copolymers, into PVC molding compositions (Böhme, K. Angew. Makrom. Chem. 47 [1975], S, 423 Szamborski, EC and Hansen, KE; Kunststoffe 65 [1965] 6, p.372), is the generation of MMA / PVC graft products (DF 2014392, DE 1801830, DE 2606190) or MMA / EVAC graft products ( DD 211571).

Of greater importance is the preparation of VC / EVAC graft polymerization products using medium pressure solution polymerization EVAC with a vinyl acetate (VAC) content of about 45% and a high average molecular weight M _n > 5000, preferably> 20000 (DE 1495694, FR 1525257, DE 1544859, DE 1544870), or high-pressure polymerization EVAC with a VAC content of between 3 and 25% and M _n > 10000 (DE 2344553, DE 2421900, DD 122686, DD 125992, DD 134232, DD 158908), which is primarily described as PVC impact modifiers are used. Using olefinic waxes, in particular EVAC waxes with 10-20Ma .-% VAC content and M _n <5000, are obtained by grafting of VC below p _s products that are also used as PVC flow improvers (DD 144924) ,

These flow improvers cause a significant increase in MFI melt index and also increase the impact strength of the PVC molding compound.

However, the use remains on PVC with Fikentscher K values> 60 because the compatibility of the VC / EVAC (10-20% VAC) wax grafting products is too low compared to PVC with K values <60, especially at Extrusion and injection molding - to obtain uniformly aufschließbare and thermostable molding compounds and thus semi-finished and finished products with high utility value.

Object of the invention

The aim of the invention is to produce by the addition of VC / EVAC graft products to PVC with Fikent K values <60 highly flowable and homogeneously aufschlauf- and processable PVC molding compositions for extrusion and / or injection molding.

Explanation of the essence of the invention

- The technical task

The invention is based on the object, highly flowable PVC molding compounds based on PVC with Fikentscher K values

between 50 and 60, which were obtained by grafting VC on EVAC to a PVC mass gain in the range of 0.8 to 3.0 at relative monomer pressures p / p _s <1 in the temperature range between 325K and 345K VC / EVAC graft polymerization in in an amount of between 0.5 and 5% by weight as flow improver.

Features of the invention

The object is achieved according to the invention by using EVAC waxes having the composition 25 to 40% by weight of vinyl acetate / 75 to 60% by weight of ethylene units and an average molecular weight M _{n of} between 1000 and 5000 as backbone polymers for the grafting.

The graft polymerization is carried out in aqueous suspension using known suspension stabilizers based on cellulose ethers and / or partially saponified polyvinyl acetates and known monomer-soluble initiators, such as diacyl peroxides, dialkyl peroxide carbonates or diazo compounds.

In addition, a known PVC crosslinking agent, such as triallyl cyanurate or maleic acid diallyl ester, may be added to the graft polymerization batch in a concentration between 0.05 and 2%, based on the EVAC wax composition, in order to more selectively adjust the graft chain structure.

The polymerization batch is a VC-Antei! in accordance with the setting of a relative pressure p / p _s generally between 0.5 and 0.9 at the respective PolymeristionstemperaturTp _m presented and continuously VC to the selected MZ corresponding to a graft PVC Anteii between 44.4 and 75 Ma .-% replenished.

The resulting VC / EVAC wax graft products are used in an amount of 0.5 to 5% by weight, preferably 1 to 3% by weight, in addition to other processing aids, such as known thermostabilizers, lubricants and pigments in the usual concentrations. the PVC molding compound mixed.

embodiment

In a jacketed pressure reactor equipped with an impeller stirrer and pressure and temperature measuring devices, 1000 parts by mass (MT) of water, which is a suspension stabilizer system 1,12MT of hydroxypropylmethylcellulose (HPMC) having a viscosity of the 0.2% solution of 1/78 mPa.s, 1.12MT HPMC having a viscosity of 1.32mPa.s and 2.75M of a partially hydrolyzed PVAC having 28 moi% residual VAC and a viscosity of the 4% solution of 4mPa.s, together with 300M EVAC wax having a VAC content of 30 wt .-%, a M _n of 2200, a melting point of 332 K and a density of 0,855g / cm ³ (EVAC-30), 2.5 MT dilauroyl peroxide (DLPO) and 0.3 MT maleic acid diallyl ester (MSDA) submitted.

After completion of the reactor pressure test with nitrogen (0.9 MPa) and several nitrogen purges (0.2-0.3 MPa), the reactor is heated to Tp _m -338 K and VC with stirring (400 U / min) up to a pressure of p -0.9MPa added.

Keeping constant T _Pm and ρ, VC is continuously added in a total amount of 500 MT from a monomer reservoir. Thereafter, the VC feed is discontinued and the reactor is depressurized after the pressure drop of 0.02 MPa, with the remainder of the VC being separately recovered, and cooled with stirring.

After thorough washing, a graft polymerization product is isolated with the following characteristics:

MZ (mass ratio of grafted-on VC to EVAC wax composition presented): 1.39 MFI (463K, 21.2N basis weight, according to TGL 25244): not measurable (nm) (product flows too fast) Particle size distribution (wet screening, according to TGL 28475/02 ):

> "000μηπ 1.8%:

> 500mm 10.6%

> 315μιτι 18,2%

> 200μηΥ 43.5% '· -.

> 63, by 24.4%

average particle size {C value J 254.8 / μm

Further experimental products are prepared by varying the polymerization conditions (p, T _Pm , different polymerized VC amounts / MZ range) _r wherein as another waxy backbone polymer EVAC-36 (36Ma .-% VAC, M _n -2700, density 0.846 g / cm ³ )

and as other initiators

Diisopropyl peroxydicarbonate (DIPP) and

2,2'-azobis (isobutyronitrile) (AIBN)

be used (see Table 1).

The resulting VC / EVAC wax graft polymerization products are the following PVC suspension products PVC-S 52 (K value after TGL37166: 52.1; bulk density SD according to TGL 14074: 0.58 g / cm ³ ; particle size KG / wet sieving according to TGL 28475/02:

> 63 / xm: 97.5%

> 25'Vm: 0.1%;

MF $ iβ to TGL 25244: 16.5g / 10min) or

PVC-S 58 (K value: 57.8, SD: 0.57 g / cm ³ , KG > 63 μνη: 98.3% and> 250 μηη <0.1%, MFI: 43 g / 10 min) mixed in and tested (stabilization with 2Ma .-% of an organic tin compound).

The results regarding flow improvement by means of 1 or 3% by mass of the graft product are listed in Table 2. The addition of the VC / EVAC wax grafting products does not degrade the thermal properties and Vicat heat resistance nor the mechanical properties of the PVC molding compound, in particular the tensile strengths σ _ζ ; on the contrary, it even gradual improvements achieved in the impact strength a _n and notched impact strength a _k (TGL 14068) at 273 K, since the proportion of "no break" for a _n by an average of 10-20% to £ 50% increase, and for a _k average is 20% higher.

The higher MFI values for the modified PVC molding compositions reported according to Table 2 clearly have an effect on the basis of the measured injection-molded spiral lengths:

PVC-S 58 without (comparison) plus1Ma .-% Nr.1 / Tab.1 plus3Ma .-% Nr.5 / Tab.1 PVC-S 52 without (comparison) plus1Ma .-% Nr.5 / Tab.1 pius3Ma .-% No.1 / Tab.1

The PVC molding compounds (K values 52 and 58) modified by EVAC waxes (VAC content of between 10 and 20%) and the corresponding VC / EVAC graft products (S.D. 144924) are also analogously modified Processing and application tests carried out with the result of a decrease in the mechanical values a _z , a _n and ak as well as the Thermostabiütäten and heat resistance. In particular, the significantly shorter injection molding lengths (on average by about 20%) and a high brittle fracture rate of about 30% indicate the inhomogeneous molding composition

- an expression of a high incompatibility.

temperature stage 437k 453K 48.5 cm 22.0 cm 59.1 cm 29.0 cm 66.7 cm 38.7 cm 67.8 cm 34.5 cm 83.3 cm 57.5 cm 92.4 cm 65.8 cm

Table 1: Preparation of VC / EVAC wax graft polymerization products

Pfropfrezeptur Init. MSDA VC Grafting conditions graft EVAC-Wax Tpm P MZ MFI No. (MT) (MT) (MT) (MT) (K) (MPa) (G / 10min.)

1 2 3 4 5 6 7 3 9 10

300 EVAC-30 300EVAC-30 300EVAC-30 30ÖEVAC-36 300 EVAC-36 300 EVAC-30 300EVAC-30 300 EVAC-36 300 EVAC-36 300 EVAC-30

2.5DLPO 2.0DLPO 2.5 DLPO 5.0AIBN 3.0 DLPO 3.0 DLPO 1.5DLPO 3.0 DLPO 2.0DIPP 2.0DIPP

0.3 1.5

3.0

500 330 600 660 600 900 300 900 400 700

338 338 338 340 338 340 340 335 330 333

0.90 1.39 n. m. 0.88 0.92 n.m. 0.90 1.60 n.m. 0.95 1.67 n.m. 0.90 1.70 n .. m .. 0.95 2.60 n.m. 0.95 0.80 n.m. 0.85 2.45 n.m. 0.72 1.20 n.m. 0.80 1.88 n.m.

Table 2: 1 Determination of the flowability of the modified PVC molding compounds Pfropfprod. (%) Table 1 PVC-S S 58 (Injection molding recipe) based on the melt indices 3.8 (G / 10min.) 2 MFI (463K, 212 N or 49, ON weight - according to TGL 25244) 3 No. 49, ON 4 PVC molding compound - 1 S 52 S 58 MF! 6.6 1.86 No. 5 - 1 S 58 12.5 - 6 1% 1 S 52 212N 18.9 See. 7 3% 1 S 52 S 58 16.5 13.1 15.8 See. 8th 1% 2 S 58 8.1 '- 9 3% 2 37.6 1.5 10 1% 3 S 52 n.m. 9.5 11 3% 3 1.3 12 1% 3 S 58 15.0   - 13 3% 4 S 52 S 58 35.2 5.9 18.5 14 1% 4 , S52 S 58 16.5 10.2 15 3% 5 S 52 S 52 35.0 16.6 16 3% 5 n.m. - 17 1% 5 33.5 - 18 3% 5 n.m. - 1% 6 8.5 3% S 52 14.8 3% S52 11.5 n.m. 65.3

19 Pfropfprod. ( ' PVC molding compound %) PVC-S S 58 MFI 11.8 -4- 252 383 20 S 58 8.3 21 No. Tab. 1 212N (G / IOmin.) No. 22 3% 6 23 1% 7 S 58 6.5 49, ON 24 1% 7 S 52 30.6 25 3% 8th S52 n. m. - 3% 8th 7.6 1% 9 S 52 33.5 14.5 1% 10 S 52 38.6 - 8.1 9.1

n. m .: not measurable, because product flows too fast without specification (-): no measurement possible, as product has too low flowability

Claims (3)

1. Highly flowable PVC molding compositions based on polyvinyl chloride having Fikentscher K values between 50 and 60, those obtained by grafting vinyl chloride onto ethylene-vinyl acetate copolymers to a PVC mass increase in the range of 0.8 to 3.0 at monomer pressures ρ below the corresponding monomer saturation pressure p _s in the temperature range between 325 and 345 K, VC / EV AC overhead polymerisation products obtained are added in an amount between 0.5 and 5% by mass as flow improver, characterized in that EVAC waxes of composition 25 to 40Ma, -% vinyl acetate / 75 to 60Ma .-% ethylene units having an average molecular weight M _n between 1000 and 5000 are used as backbone polymers for the grafting. 2. The method according to item 1, characterized in that the graft polymerization in aqueous suspension using known Suspensionsstabiiisatoren based on cellulose ethers and / or teilverseifter polyvinyl acetates and known monomer-soluble initiators, such as diacyl peroxides, Dialkylperoxidicarbonste or diazo compounds is performed. 3. Process according to items 1 and 2, characterized in that a known PVC crosslinking agent, such as triallyl cyanurate or maleic acid diallyl ester, is added to the graft polymerization batch in a concentration between 0.05 and 2%, based on the EVAC wax composition.