DD292464A5 - PROCESS FOR PRODUCING PVC PASTE PRODUCTS - Google Patents

Abstract

PVC paste product; Microsuspension PVC; peroxydicarbonate; Oil-soluble metal compound of I. to VIII. Subgroup of the PSE + water-soluble metal compound of the I. to VIII. Subgroup of the PSE + subgroup of the PSE; Space-time yield

Description

Field of application of the invention

The invention relates to a process for the preparation of PVC paste products for the preparation of high-soft foams for coatings and coatings according to the microsuspension method.

Characteristic of the known state of the art

It is known that PVC pastes, d. H. Blend mixtures of polyvinyl chloride and plasticizer, using chemical blowing agents to thereby obtain fine-pored closed-cell structures (Kunststoffe 68 [1978] 12,800). To achieve sufficient foamability, the use of special surfactants is described, such. As potassium salts of alkylbenzenesulfonic acid (DE-OS 2246508), zinc or strontium salts of carboxylic acids (DE-OS 2538389 and US 3795634). However, these specialty products require special heightening processes.

It is also known to produce standard emulsifiers or emulsifier foamable products by the continuous emulsion process (DE-OS 2428706), which, however, give only average paste viscosities with low thermal stability.

It is also known to produce foamable products by the microsuspension process. Thus, foaming of low- and medium-viscosity plastisols is achieved by an emulsifier combination with carboxylic acids (DD-WP 216941).

(US 4186259), however, the latex stability is insufficient at low emulsifier levels.

The production of foamable coatings with improved performance properties requires the use of highly viscous PVC pastes.

It is known to produce highly viscous paste products by the discontinuous emulsion process (DE-OS 2428706), which can be processed into foamable coatings of high quality, for the microsuspension method that is not possible.

Another problem is the highly autocatalytic nature of vinyl chloride polymerization. The due to the rapidly increasing reaction rate, especially in the field of high sales, occurring amounts of heat, especially in large-scale systems, the space-time yield significantly.

Methods are known which are intended to enable a uniform reaction rate when using oil-soluble initiators and special redox systems (US Pat. No. 3,985,718, US Pat. No. 3,954,664) consisting of metal chelate compounds and electron donors as well as complexing agents. However, these processes are not suitable for technical polymerizations due to the high amounts of the auxiliaries used, both in qualitative and in economic terms with respect to the end product.

To even out the course of the reaction of vinyl chloride polymerization, a method is also known (DD-WP 152 347) in which using diacyl peroxides and peroxydicarbonates and a redox system consisting of an oil-soluble and / or water-soluble metal compound of I.-VIII. Subgroup of the PSE in amounts of 0.005 to 0.1 mol / mol of initiator, which is added before or during the polymerization, and a water-soluble and / or partially oil-soluble reducing agent in amounts of 2 to IOOM0I / M0I the metal compound, intermittently or continuously added ,

However, this process generally produces low-viscosity paste products which are not suitable for producing foamable coatings of the required quality level.

It must therefore be stated that it has hitherto not been possible by polymerization of vinyl chloride in microsuspension to carry out a highly productive process for the preparation of highly viscous paste products for producing foamable coatings of high quality in accordance with the application requirements.

But the economic reason in the production of a variety of PVC paste types requires for a potential producer to do this as much as possible according to a process principle and a uniform technology with a simultaneously high productivity. This is not possible according to the prior art.

Object of the invention

The aim of the invention is the production of PVC paste products for the preparation of high-soft foams with excellent processing properties, while high productivity of the process.

Explanation of the essence of the invention

The invention has for its object to develop a process for the preparation of PVC paste products according to the principle of Mikrosüspensionspolymerisation, which leads to products having a particularly high plastisol viscosity, the reaction sequence is to influence so that a high space-time yield is ensured ,

The object is achieved according to the invention by intermittently or continuously adding at a polymerization temperature of 320 to 328 K up to a conversion of 20% by weight in% only 1 to 70 parts by weight in% of the conventional amount of reducing agent for a conversion rate of 8 to 15% / h becomes.

The procedure according to the invention surprisingly provides, according to the principle of microsuspension polymerization, PVC paste products which form plastisol with very high viscosities and are suitable for the preparation of highly soft foams having excellent processing properties. At the same time it is possible with this procedure to influence the reaction process so that a high space-time yield is achieved.

Exemplary embodiments

example 1

In a pressure vessel of 10m ³ content are 4.2t water, 4.4t vinyl chloride, 2.64kg dilauroyl peroxide and 0.53kg

Dicetyl peroxydicarbonate and 44 kg of sodium lauryl sulfate and 22 kg of an alkyl sulfonate submitted.

The mixture is emulsified in a known manner by means of a homogenizer to the appropriate particle size and then heated to a polymerization temperature of 323 K. During the heating phase, the approach 72g

CuSO ₄ - 5H ₂ O added as an aqueous solution.

The stirring takes place by means of an inclined blade stirrer at peripheral speeds of 0.25 to 0.5 m / s. Just before reaching the

Polymerization temperature is measured with the dosage of the reducing component, a 0.16% ascorbic acid solution,

enjoy! ^. The metering is carried out such that during the first 4 hours, an amount of 4 l / h in the further 4 hours, an amount of 8 l / h and in the last 4 hours, an amount of 6 l / h are fed into the polymerization vessel.

After completion of the polymerization results in a latex having a solids content of 47.2%, which corresponds to a real conversion of 85.3%. The work-up of the latex is carried out by spray drying.

A paste made of 50 parts PVC and 50 parts DOP has a viscosity of 142500 mPas at a shear rate of 0.33 s -1 and a viscosity of 13800 mPas at a shear rate of 48.6 s.

Example 2 and 3

The procedure is analogous to Example 1. The dosage of the ascorbic acid solution is as given in Table 1. The obtained latex and product parameters are also shown in Table 1.

Table 1

FS Sales Viscosities (mPas) (%) (%) PVC: DOP = 50:50 Dr = O ₁ SSs " ¹ 48.6s" ¹

47.8 87.4 125000 10800

47.5 86.4 160000 12600

Dosage of amount ascorbic acid 6l / h Time 10 l / h Example 2 2.5 h 8 l / h 1.5 hours 6l / h 2h 4 l / h 4h 2l / h 2h 4 l / h Example 3 2h 10 l / h 2h 81 / h 2h 6 l / h 4h 2h

Example 4 (Comparative Example)

The procedure is analogous to Example 1. However, the addition of ascorbic acid is carried out according to the usual metering regime in which a constant reaction rate of 8% / h of conversion is achieved. It will be 4 hours long amount of 101 / h

dosed, then another 3h 8l / h and added at the end again 3h 61 / h.

After completion of the polymerization results in a latex having a solids content of 47.4%, which corresponds to a conversion of 86.0%.

After working up the latex by spray drying, the following viscosities were obtained for the pastes made from this product.

Ratio PVC: DOP = 50:50

= 18200mPas at Dr. med. = 0.33s! " ¹

= 3650mPas with Dr. med. = 48.6s " ¹ .

Claims (3)

1. A process for the preparation of PVC paste products for the preparation of high-soft foams according to the principle of microsuspension polymerization. Using a mass fraction of 0.03 to 0.3% diacyl peroxides based on the monomer and / or 0.005 to 0.05 mass% Peroxidikarbonate based on the monomer, 0.005 to 0.3 mol / mol of an oil-soluble and / or water-soluble metal compound of I, to VIII. subgroup of the PSE, preferably a copper compound, based on the peroxo compounds and 2 to 50 mol / mol of a water and / or partially oil-soluble reducing agent, preferably ascorbic acid, based on the metal compound and known emulsifiers in mass fractions in% of 0.5 to 3.0 based on the monomer, characterized in that at a polymerization temperature of 320 to 328 K up to a conversion of 20 % By weight only 1 to 70 parts by weight in% of the conventional amount of Red for a turnover rate of 8 to 15% / h is added. 2. The method according to claim 1, characterized in that the reducing agent is added continuously. 3. The method according to claim 1, characterized in that the reducing agent is added intermittently.