DD216244A1 - METHOD FOR PRODUCING SINTERING FINE-PARTICULAR VINYL LIQID POLYMER - Google Patents

Abstract

Sintered finely divided vinyl chloride polymers with Fikent's K values 58-70, Schuettdichten 0.4-0.7 g / cm high 3, plasticizer uptake 8-20% by mass DOP, average particle size diameters 10-50 mym, with grain sizes over 63 mym <5% , and thermostabilities> 30 min, which can be processed into plates (micro-cutter) for lead-acid batteries with a surface resistance of <20 m ohm / dm high 2 and a good H deep 2 SO deep 4 wettability are thereby produced, d. Vinyl chloride (VC) under known Suspensionpolymerisationsbedingungen is homopolymerized to a monomer conversion between 70 and 90%, to a residual VC pressure between 0.01 and 0.1 MPa relaxed and then 0.5-10% vinyl acetate, based on the VC- Homopolymermasse, is copolymerized under conditions of Gelphasenpfropfpolymerisation. As suspension stabilizers, particularly high-viscosity cellulose ethers with a viscosity> 100 cp and polyvinyl alcohols with residual acetate contents <25% and Fikentscher K values> 60 are suitable. The resulting VC-VAC copolymers do not require a separate demonomerization step.

Description

Title of the invention

Process for the preparation of sinterable finely divided vinyl chloride polymers

Field of application of the invention

The invention relates to a process for the preparation of sinterable finely divided vinyl chloride polymers with

ή λ mw A (\ Q O u and i \ Ott ·.) Ö (I

Fikentaeher K values 58-70,

Bulk densities 0.4 - 0.7 g / cm · ⁵ ,

Plasticizer pickup: 8-20% mASS DOP, average grain size

knives 10 to 50 per cent, with grain sizes over 63 per cent in 5 per cent, and thermal stabilities in 30 per cent,

to separator plates (microsepsers) with an electric

    2 surface resistivity of 20 m-ohms / dm and a good HpSO 3 wettability, based on the polymerization of vinyl chloride (VC) in aqueous suspension using known suspension stabilizers and oil-soluble initiators in the temperature range 310-350 K. ·

Characteristic of the known technical solutions

Of the polymeric materials are particularly suitable halogen-containing polymers such. B · PT ¹ E and PVC, due to its high intermolecular forces for shaping by sintering · PVC, which has been adapted in its powder characteristics the sintering process can be unstabilized economically processed into porous plates, particularly for high-quality separation elements of the electrodes in batteries have been optimized in terms of application (H · Kraus, Plastverarbeiter 2J ^ 1976 ^ 7 5 »259).

The polymers (PVC-S) obtained by the most commonly used suspension polymerization process of vinyl chloride (VC) generally have too high a mean grain size (KG) and a too large particle size distribution (KGV) in order to obtain finely porous sintered plates by means of belt sintering methods they have a bad wettability and therefore one for the electrolyte by the

r »ill» I

.,. ηOttα

Therefore, the VC suspension polymers prepared using known suspension stabilizers, optionally with the addition of emulsifiers (sodium salts of alkylbenzene sulfonic acids), are mixed with emulsion PVC, including small amounts of a nonionic antistatic agent (DE-OS 2127654 Although this improves wettability, the mechanical properties of the sintered plates, which moreover tend to foam in the electrical cells because of the proportion of emulsifier, are worsened

Another possible combination between favorable PVC-S and PVC-E properties is a two-stage process, which is followed by a suspension polymerization (as auxiliaries: cellulose ethers / partially saponified polyvinyl acetate, oil-soluble peroxidic initiators, NaHCO 2 ^, buffer) with the addition of emulsifiers (alkali metal salts of fatty acids ) and water-soluble persulfates is polymerized under Emulsibnsbedingungen to the end (DE-AS 2337 361).

If the suspension polymerization is carried out by means of a dispersant sy st ems from a cellulose ether and an anionic emulsifier, sinte, viable finely divided PVC products can also be achieved if, after a certain high degree of conversion, the polymerization is continued after addition of a water-soluble initiator (FR-PS 2393 815j DE-AS 2861 393).

The disadvantage of these process variants is the high sensitivity of the polymerization recipe and technology to obtain PVC with a narrow P / E and uniform porosity.

The disadvantages caused by mixing PVC-S and PVC-E or combination of VC-suspension and VC emulsion polymerization are eliminated if, instead of the sodium sulfonates known as emulsifiers, the corresponding free sulfonic acids are used together with nonionic wetting agents (EB-OS 2310 431) Although the sintered plates obtained after the usual processing have good wettability and satisfactory mechanical properties, thermal stability and processability on the plate sintering machines are reduced because of the insufficient flowability and meterability of the powder (DE-OS 2310 431).

This disadvantage is largely eliminated "if * ^s that are stored in the PVC molding composition free sulfonic acids, which may be partially additionally added after the polymerization (DS-OS 2 402 314) $ are neutralized by special organic tertiary imines, wherein the presence of non-ionic wetting agent in the polymerization mixture is not absolutely necessary (DE-OS 2646 595) · The separators produced from these molding compositions have improved mechanical and electrical properties, but due to their relatively large average pore diameter and the resulting plate thicknesses in terms of material savings in plate production and the increased risk the "by growing ¹¹ of the plates with electrically conductive rainfall and thus the formation of so-called jumpers limited ·

The preparation of thinner separator plates is possible because of the improved electrical and mechanical properties of suspension polymers obtained by VC suspension polymerisation in the presence of ethylene-vinyl acetate copolymers (EVA) with BVA contents of 0.3-15 mass% ( DE-OS 3018 922).

The use of volatile VC copolymers, such as VC-vinylidene chloride (VDC) copolymers, for the preparation of porous battery separators is also known (Japanese Patent Laid-Open 81/59498). Among the VC copolymers, the VC-vinyl acetate (VAC) copolymers occupy a top position in terms of their production amount · Both by the usual technical suspension, emulsion or Lösungspolymerisationsverfahren (DB-OS 1901 518, 1918 414 »2023 97Oj DB-JiS 1299 422, 1937 237) as well as by grafting of PVC on PVC DB-OS 1720 844, 2056 372 DE-AS 1085 355, 1155 607, DD-TSP 129 562, 140 462) do not fulfill the requirements placed on the production of separator plates.

In addition, the known processes using comonomers (VAC, VDC) or blastomers (EVA) are uneconomical, since they require additional technical and technological expenditure (dissolution of EVA in VC, comonomer recovery and high demonomerization effort).

Object of the invention

The object of the invention is based on the VC suspension polymerization finely divided sinterable VC polymers with little technical and technological effort, in particular without additional Entmonomerisierungsstufe to produce, by means of known band sintering method to separators with sufficient mechanical and electrical characteristics for lead-acid batteries can be processed ·

Explanation of the essence of the invention - The technical task

The invention is based on the object, a method for producing finely divided sinterable VC polymerizates with

a Fikentscher K value between 58 and 70, a bulk density between 0.4 and 0.7

g / cnr, a plasticizer pick-up between 8 and 20

Mass% DOP,

a mean grain size between 10 and 50 ^ t , a narrow particle size distribution, with particle sizes over 63 yum ^ - 5 % t

a thermostability - ^ - 30 min

as well as mechanical characteristics and sintering properties, which have a good processing behavior on the known band sintering plants at temperatures between 420 and 490 K and after sintering to plates an electric

'' '. p

Sheet resistance of ^ -2Om ohms / dm and a good R ^ SO, employability to develop based on the VC suspension polymerization in the temperature range between 310 and 350 K to develop.

Features of the invention

The object is achieved according to the invention by homopolymerizing VC in a known manner to a conversion of between 70 and 90% by mass in aqueous suspension, depressurizing to a residual VO monomer pressure between 0.01 and 0.1 MPa and subsequently under conditions known from the art Gel phase graft polymerization vinyl acetate in an amount between 0.5 and 10 %, based on the VC Homopolymerisatmasse copolymerized

As suspension stabilizers are particularly higher viscosity substances such as cellulose ethers having a viscosity

^ 100 cP (2% solution, 298 K), polyvinyl alcohols with Pikentaeher K values ^ 60 and residual acetate contents L x 25 % or the Na salt of styrene-maleic anhydride copolymers, in concentrations of 0.1 to 1.0 % _t based on the mass of water, used ·

Furthermore, to improve the dispersion further substances (auxiliary dispersants), in particular those with emulsifying effect, such as glycerol and sorbitol esters, are used. "In addition, the usual additions of electrolytes and / or buffer substances"

Ausführungabeispiel

In an equipped with a stirring and pressure measuring, temperature-controlled and oxygen-free purged polymerization autoclave to 1000 parts by mass (MT) of an aqueous solution containing 3 MT teilverseiftes polyvinyl acetate (16% by weight residual acetate, Pikentscher K value 68 '* PVA) .iatorgemisch, consisting of 0.14 MT diisopropyl peroxydicarbonate (DIPP) and 0.4 MT dilauroyl peroxide (LPO), 3 MT sorbitan monolaurate (SML) and 0.4 added.

Subsequently, 580 MT VC are pressed and the polymerization batch heated to a temperature T- of 335 K and polymerized at constant T to a pressure drop of 0.2 MPa. Thereafter, the unreacted VC bulk is separated by means of relaxation and the PVC suspension, the still contains a VC residual monomer content of 1200 ppm, added 50 MT VAC and 0.05 MT DIP and heated to a polymerization temperature T £ of 340 K.

Under these conditions, the VAC in the forming polymer (in situ PVC-S) / monomer (VAC / low

VC-amounts) -Gelphase grafted onto the PVC · After 2 hours of polymerization, the reaction is stopped by .Spreading, the unreacted VAC removed by N ₂ purge and the VAC monomer recovery fed.

A graft polymer product having a grafted VAC content of 4.3%, based on the total polymer composition, and a residual VC monomer content of Z-5 ppm and the following characteristics are obtained:

K value 65 Bulk density (SD) (TGL 14 074) 0.56 g / cm ³ Plasticizer Absorption (WMA) 13 mass% DOP average grain sizes knife (cTjj). 22 / am Grain size distribution (TGL 20 645) closely - * 63 / am 2.3% Λ125 / am O methanol extract 0.3 % Thermoatabilität 55 min / "" Stabilimeter procedure after TGL 28 475/02, after 10 min Rolling at 453 K 7

At a sintering temperature of 455 K, micro-separator plates with a maximum pore diameter of 60 μm and an elekr

'2' trischen sheet resistance of 12 m ohms / dm produced

become.

With variation of the type and amount of polymerization aids (suspension stabilizers, emulsifiers, initiators, sometimes also charged with the vinyl acetate) and the homo- and graft polymerization (temperatures, vinyl acetate) are further sinterable finely divided VC polymers in

K value range of 60.-70, SD of 0.53-0 ^N , 58 g / cm x ³ , narrow particle size distribution and no particle size fraction ^ 125 / μm and thermal stabilities -50 min <> (stabilimeter method according to TGL 28 475 / 02) (see Table 1). As important product parameters, in addition to the K value, the mean grain size diameter ()) and the grain size proportion - 63 63 / am are listed. The concentration data always refer to the water mass and the amounts for the monomers used (VO, VAC) to 0 water.

In addition to the polymerization auxiliaries stated in the example described, the following were used:

Suspension Stabilizers: Methylcellulose (MC)

(Viscosity of a 2% solution, 296 K - 120 cP),

a saponified with NaOH

Styrene-maleic anhydride copolymer

(S / MA);

Auxiliary disperser: glycerol monostearate (GMS); (Emulsifier) '

Initiators: dicetylperoxidicarboate (DCP),

Distearylperoxidicarbonat (DSP), oc, a-azobisisobutyronitrile (AIBN).

Table 1

Dispersant initiator

p-waste

VC / VAC share £ "WiJ

K value

KG Λ 63 / ura

0.3 0.3

PVA SML

0 ^ 5 PVA

0,3 SIiIL

0.3 PVA

0.3 GLOS

0.2 0.3

MC SML

0.25 S / MSA 0.3 SML

0.4 PVA 0.4 GMS

0.014 DIP 335

0.04 LPO 340

+ 0.005 DIP

0.02 DIP 330

0.05 LPO 335

0.02 DSP 340

0.05 LPO 340

+ 0.005 LPO

0.02 0.04

DSP LPO

0.015 DGP 0.05 AIBW

333 337

337

337

0.015 DIP 330 0.03 LPO 335 +0.005 LPO

0.2

0.15 0.3

0.2 0.3 0.15

58/5

60/5 60/3

63/6 55/5 63/5

65

68

61

66

69

22

25

20

25

28

15

2.3

3.2

1.8

2.5

3.1

2.1

Claims (2)

invention claim 1 · Process for the preparation of sinterable finely divided vinyl chloride polymer with the au Separatorplatten (micro-separator) with an electrical sheet resistance of ^ - 20 m Ohm / dm and a good E ^ SO ^ -etzetzbarkeit can be processed, based on the polymerization of vinyl chloride in aqueous suspension using known suspension stabilizers and oil-soluble initiators in the temperature range between 310 and 350 K, characterized in that vinyl chloride is homopolymerized in known manner to a conversion between 70 and 90% by mass in aqueous suspension, to a '. VC residual monomer pressure between Ö, O1 and 0.1 MPa relaxed and subsequent vinyl acetate in an amount between 0.5 and 10 % _t, based on the VC Homopоymermermasse, copolymerized under conditions of the known Gelphasenpfropfpolymerisätion. 2. The method according to item 1, characterized in that as suspension stabilizers higher viscosity substances, such as cellulose ethers having a viscosity ^ 100 cP (2% solution, 298 K), polyvinyl alcohols with Pikentscher K values ^ 60 and residual acetate contents ^ 25 % or the sodium salt of styrene-Haleinsäureanhydrid copolymers, used in concentrations of 0.1 to _1.0%% to be used on the water mass ·