CZ166496A3 - Plastisol composition, process of its preparation and use - Google Patents

Abstract

The description relates to a plastisol composition based on pearl polymers. The pearl polymers preferably have a core/shell structure and an average diameter of 1 to 150 mu m. They are advantageously free of chlorine and consist at least of a) styrene, alpha -methyl styrene and/or p-methyl styrene and b) 2 to 20 wt. % (in relation to the copolymer) of olefinically unsaturated carboxylic acids. The plastisol composition of the invention can be used in the production of coating compounds, sealants and adhesives.

Description

TECHNICAL FIELD ^H i • 'í'2

The present invention relates to a novel plastisol composition of bead polymers, plasticizers and inorganic fillers and optionally other conventional additives.

BACKGROUND OF THE INVENTION The term plastisols generally refers to dispersions of organic plastics in plasticizers that gelt when cured to a higher temperature and cure when cooled. The plastisols still used in practice today contain predominantly finely powdered polyvinyl chloride (PVC), which is dispersed in a liquid plasticizer and forms a paste. Such polyvinyl chloride plastisols are used for a variety of purposes, inter alia as sealants, eg for sealing welds in metal containers or as glue welds in the metal industry, as corrosion protective coatings for metals (eg underpants), for covering and impregnating

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- textile materials (eg the underside of carpets), such as cable insulation from etc.

However, a number of difficulties are encountered in the production and use of PVC plastisols. PVC production itself is no longer a problem, since employees are exposed to health hazards with monomeric vinyl chloride. In addition, vinyl chloride monomer residues in PVC can also be harmful to health during further processing or for end users, although its concentrations are generally in the ppb range.

When PVC plastisols are used, it is particularly important that PVC is sensitive to both light and heat and tends to cleave hydrogen chloride. This is a particularly serious problem when the plastisol has to be heated to a higher temperature and the hydrogen chloride released under these conditions is corrosive and attacks the metals. This is particularly true when relatively high firing temperatures are used to shorten the gelling time, or when the spot heat is heated locally to a high temperature.

The biggest problem arises in the treatment of wastes containing

PVC: besides hydrogen chloride, dioxins can be formed, among others, whose high toxicity is well known. In conjunction with scrap iron, PVC residues can lead to an increase in the PVC content of the melt, which is also disadvantageous.

It is therefore an object of the present invention to provide a PVC-free plastisol composition whose utility properties correspond to PVC-plastisols.

Polyurethane or acrylate based coating materials have already become known, which are used, for example, in the automotive industry instead of PVC plastisols.

Two-component polyurethane systems are fundamentally different from conventional plastisols in use, and users usually do not have the complex equipment necessary to process them.

One-component polyurethane systems are also known, but all have a number of other disadvantages:

- air humidity curing systems have a high viscosity and cannot be applied without 25 solvents

- in systems with blocked isocyanate groups, the volatility of the blocking agent can lead to the formation of bubbles in thick layers, moreover, the required temperature range of 150 ° C to 180 ° C can often not be maintained under firing conditions.

- aqueous polyurethane dispersions are not suitable for conventional production processes because of the evaporating water.

- micro-encapsulated polyurethane systems (mikroverkapselte Systeme) have insufficient shear stability, which in use leads to gelling in pumps.

Although acrylic plastisols disclosed in DE-B-24 54 235 and DE-B25 29 732 largely meet the above-mentioned technical requirements, the required acrylate polymers are also much more expensive than polyvinyl chloride, so that the use of these acrylate plastisols also remains limited for special purposes, eg as spot welding pastes where PVC plastisols fail completely. The plastisols based on acrylonitrile / styrene blended polymerizates according to EP-A-261 499 are also not a satisfactory solution due to the lack of wear and / or storage stability.

DE-A-41 39 382 proposes core / shell polymer (Kern / Schale-Polymeren) polymers in which the core of the polymer particle is a diene elastomer and the shell consists of a continuous layer of methyl methacrylic resin, acrylonitrile resin or vinyl chloride polymer.

The two shell materials meet the requirement for a chlorine-free polymer, but require a high proportion of hard shell material for the long-term stability of the plastisol polymer particles. Since these proportions of polymer are at least partially incompatible with the plasticizer, heterodisperse systems are formed after the gelling process which cannot achieve optimum performance properties.

The vinyl chloride polymer, as the shell material, is reduced against pure

PVC-plastisols have a chlorine content, but because they are not completely chlorine-free, these polymers represent only a less satisfactory partial solution to the problem.

DE-A-40 34 725 discloses that plastisol compositions having excellent utility properties, particularly good shelf life, good adhesion to metals and high abrasion resistance, and good mechanical properties can be obtained when styrene copolymer powders are used as organic polymer components, which can be produced by emulsion polymerization containing

(a) Styrene and / or α-methylstyrene and / or p-methylstyrene; and

b) 3 to 20% by weight (based on the copolymer) of methacrylic acid and / or acrylic acid and / or itaconic acid

By emulsion polymerization of these styrene copolymers, polymer particles with a uniform average primary particle size of from about 0.3 to 1.5 microns can be obtained in which the polar carboxyl groups are mainly arranged outwardly and, as lipophobic residues, are apparently responsible for the stability of the dispersions of these particles in the plasticizer at room temperature. These copolymers have a molecular weight of the order of

20000 to 1000000.

Typically, the polymer dispersion is dried by a spray drying method. In the case of chlorine-free polymers, there are still further problems, in that very fine polymer powders tend to explode dust due to their very low ignition energy. In order to avoid this risk during drying, the chlorine-free polymer dispersion must be spray-dried under inert conditions, which, however, makes the polymer production process considerably more expensive. It is therefore an object of the present invention to provide chlorine-free polymer powders for use in plastisols which do not require an expensive spray-drying method under inert conditions.

It has now been found that from certain bead polymers after simple filtration and subsequent drying and the addition of plasticizers,

5 other conventional additives can be used to produce plastisols suitable as adhesives, sealants and / or surface coatings.

Bead polymerization, often also called suspension polymerization, has been known for a long time. In this process, the water-insoluble organic monomer is suspended in a known manner by means of protective colloids and / or stabilizers as dispersants in the aqueous phase, and particles of a larger or smaller size polymer are formed. Water-insoluble inorganic salts are often used as protective colloids and / or stabilizers.

Usually, these salts are separated and removed during processing of the polymers, for example by reaction with acids.

It has now been found that, surprisingly, these inorganic components can remain in the polymer, so that the processing process becomes particularly simple and thus economical.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides bead polymerizable plastisol compositions which, after polymerization, are filtered from the aqueous phase without further processing and subsequently removed therefrom.

2on some normal way of residual moisture.

The dispersing aids are selected in such a way that they do not have any interfering effect on the plastisol composition, preferably they are at least partially a normal part of plastisol. The inorganic component of this dispersing aid - also called Pickering emulsifier - is therefore preferably barium sulfate, calcium carbonate, magnesium carbonate, calcium silicate or aluminosilicate. In addition, ionic or nonionic emulsifiers such as sodium cetyl stearyl alcohol sulfate are added in small amounts.

In principle, all polymers capable of free-radical polymerization with low water solubility can be used for this suspension polymerization process, but are preferably polymerized in this way and styrene-methacrylic acid or styrene-acrylic acid copolymers used in the plastisols of the invention, such as are described in DE-A-40 34 725. In this case, the entire amount of monomers can be used all at once or styrene is initially added and methacrylic acid or acrylic acid is added during the polymerization. By varying the solubility of the monomers in the polymer or in the water, it is possible to achieve a gradient of the (meth) acrylic acid concentration in the particle cross-section as well. This is desirable because there is a statistically sufficient amount of carboxylic acids in each polymer molecule for later crosslinking reactions and / or adhesion mediations. The particle size of the polymer can be varied within wide limits by appropriate choice of monomer concentration, monomer is / dispersant ratio, or speed and / or agitator geometry. The mean particle size of the bead polymers for plastisols of the invention is between 1 µm and 150 µm, preferably between 5 µm and 60 µm.

The resulting polymer can be easily separated from the water by filtration and subsequent drying at 50 to 150 ° C, preferably at 60 to 100 ° C, and can be directly used for the production of plastisol, the inorganic dispersant component remaining in the polymer serving as a filler which is necessary in plastisol anyway. Since the aforementioned drying process only serves to remove residual moisture after filtration, low-cost and therefore cost-effective belt drying or fluid bed drying methods are possible in this step. Surprisingly, the minimum ignition energy of these suspension polymers is increased by a factor of about 1000 compared to the polymers produced according to DE-A-40 34 725 by spray-drying method. This is desirable since polymers with such a high minimum ignition energy are desirable.

3o handle without risk of inert atmosphere.

• · Λ. · ‘

In addition to the abovementioned comonomers, the comonomers disclosed in DE-A-40 34 725, which are expressly incorporated herein by reference, may also be used.

Per 100 parts by weight of the styrene copolymer, the 5 plastisol preparation according to the invention contains about 30 to 1000 parts by weight of plasticizer. Conventional organic plasticizers are used as plasticizers (cf. Paul E. Bruins, Plasticizer Technology (Weinhold Publishing Corporation, New York), Part 1, pp. 228-223). Diodeonyl phthalate (DINP) is also suitable, but also known plasticizers from the group of organic phosphates, adipates and sebacates or benzyl benzoate or diphenyl ether are also suitable.

In addition to the aforementioned additives, the plastisols of the invention may also contain conventional additives useful in plastisol technology, including, but not limited to, fillers such as calcium carbonate in the form of various chalk, barite, mica, vermiculite, pigments such as titanium dioxide, carbon black, oxides. iron, blowing agent for forming foamed plastisols, anti-aging agents, means for adjusting theological properties such as pyrogenic silicic acid, bentonites, castor oil derivatives.

The plastisols according to the invention are suitable for the production of automobiles, in particular for the protection of the underbody, as well as adhesives for bonnet lining,

as a threshold protection material and as a spot welding paste, as well as for other types of gluing. In the packaging industry, they can find use as sealants for container closures such as crown bottle caps, as weld seals and glue seams for cans.

In addition, these plastisols can also be used for many other technical applications, including, but not limited to, wallpaper and textile coating materials, floor coverings, disc coating, eg in the manufacture of cars and other µ vehicles, analogously to the method described in EP-B- 333,538, as an adhesive for the production of multi-layered safety glass.

The following examples should serve to illustrate the invention in greater detail:

DETAILED DESCRIPTION OF THE INVENTION

The polymerization reaction is carried out in a stirred reactor (R). The reactor is equipped with a stirrer consisting of three MIG stages and stops. The stirrer speed is infinitely adjustable. The container (V) is used as a template. The template is weighed and connected to the reactor via a stainless steel pipe. Content dosing is an automatic preselection of the appropriate speed. Reactor R has different heating and / or heating. cooling circuits. By means of two separate temperature sensors (product temperature) built in the reactor, the device can be operated in the temperature range from 15 ° C to 120 ° C. Nitrogen can be supplied to create an inert atmosphere in the reactor R.

Water, styrene, initiator and emulsifier are added to the reactor. After heating to the reaction temperature (80-90 ° C), the thermal decomposition of the polymer peroxide used begins.

The methacrylic acid metered into the reactor from the master V is gravimetrically controlled and takes place during the first three to four hours of the reaction. The total reaction time is 7 to 8 hours.

Excess heat of reaction is removed from the reactor by water cooling.

The present process is a simple free-radical copolymerization of styrene with methacrylic acid in an aqueous slurry with a water content of about 50%. The polymerization is initiated by dibenzoyl peroxide or similar water-soluble initiators by thermal radical formation.

After completion of the reaction, the dispersion is cooled (< 45 ° C) and drawn through a belt filter. Residual moisture is removed in the downstream dryer. The powder obtained can be used directly to produce plastisols; storage stable plastisols are formed. -..... - _; r '^;

-9 Example 1: Polymerization Formulation A (2 I device)

Navážka Weight parts Water 750.0 g 44,2% Styren 750.0 g 44,2% Kys. methacrylic 45,0 g 2.6% Barium sulphate 150.0 g 8.8% Dibenzoyl peroxide 3.8 g 0.2% Lanette E 0.1 g ⁴ Stirrer speed: 500 ^min-1 Reaction time: 450 min

Water, barium sulphate and Lanette ER (sodium cetyl stearyl alcohol alcohol) are placed in a 2L double-jacketed vessel equipped with a reflux condenser and a three-stage MIG stirrer (diameter 90% internal reactor diameter). The dibenzoyl peroxide initiator is dissolved in styrene. This solution is completely transferred to the reactor under stirring (at defined speed). Nitrogen is passed through the solution to ensure inert conditions. The contents were warmed to reaction temperature and temperature over 30 minutes. When the reaction temperature is reached, methacrylic acid dosing begins. The comonomers are dosed evenly over 3 hours. The progress of the reaction is monitored by gravimetric determination of the solids content. After 7.5 hours, the polymerization is complete. The solid is filtered off under suction and dried at approximately 50 ° C.

- 10 Analytical data:

Particle size: _with X = 38 pm

Molecular weight: M _w = 136,000; M _n = 48000

Example 2: Polymerization recipe B (25 I device)

Navážka Weight parts Water 12000,0 g 61.3% Styren 6000,0 g 30.6% Kys. methacrylic 360.0 g 1.9% Barium sulphate 1200.0 g 6,1% Dibenzoyl peroxide 24,0 g 0.1% Lanette E 1.2 g Stirrer speed: 300 ^min-1 Reaction time: 450 min

The reaction proceeds analogously to Example 1 in a double-jacketed glass reactor, which is also equipped with a three-stage stirrer 10 MIG (90% of the internal diameter of the reactor). The stirrer speed corresponds to the same peripheral speed as in the 2 L device.

-11 Analytical data:

Particle size: X ₅₀ = 106 µm

Molecular weight: M _w = 316,000; M _n = 107,000

Example 3: Plastisol recipe

Navážka Weight parts The SMA polymer of Example 1 41.6 g 43.9% Barium sulphate 4.4 g 17.2% Diisononyl phthalate 22,5 g 29.9% Aerosil 200 0.3 g 0.4 g Versamid 140 1.5 g 2.0% Dicycloheptyl phthalate 5.0 g 6,6 g

^{5 The} SMA polymer charge consists of 79% polymer and 11% barium sulphate (corresponding to the polymerization formula).

Plastisol is weighed into a beaker according to the recipe and homogenized.

Viscosity measurements were carried out on a CARRI-MED CS rheometer (plate / plate; diameter = 4 cm) to test storage stability: measurements of freshly produced plastisol and measurements after three days at 25 ° C showed practically identical values for the viscosity in Pas with at shear speed (1 / s).

- 12 No significant gelling was observed. After application of the film (400 pm) on the sheet and subsequent tempering (15 min at 160 ° C), homogeneous coatings were obtained with adequate appearance and mechanical stability (visual assessment).

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Claims i

Claims (11)

First Plastisoiový agent based bead polymfer & áitůl 9 ¹ characterized in that the bead; · Λ 2. The plastisioid composition of claim 1, wherein the polymer particles of the bead polymer or bead polymerisate have a core-shell structure. Plastisium composition according to one of Claims 1 to 2, characterized in that the primary particles The 20 bead polymers or bead polymers have an average diameter of from 1 to 150 µm, preferably from 5 to 60 µm. Plastisioid composition according to one of Claims 1 to 3, characterized in that it is dispersing The composition comprises a water insoluble inorganic salt and an ionic and / or nonionic emulsifier. - 14 5 · Plastisol composition according to any one of claims 1 to 4, characterized in that it comprises a) 5 to 50% by weight of a bead polymer b) 5 to 60% by weight of a plasticizer c) 5 to 40% by weight of fillers d) 0-10% by weight of the adhesive composition e) 0-10% by weight of crosslinker f) 0-10% by weight of the Theological adjuvant g) 0 to 5% by weight of other conventional additives and / or auxiliaries for plastisols. The polymerizate used is a copolymer, containing a polymer (a) styrene and / or α-methylstyrene and / or p-methylstyrene; and b) 2 to 20% by weight (based on the copolymer) of olefinically unsaturated carboxylic acids, for example methacrylic acid and / or acrylic acid and / or acid A method for producing a plastisol composition according to any one of claims 1 to 5, characterized in that: After the polymerization, the bead polymer is separated from the aqueous phase by filtration and then dried at a temperature of about 50 ° C to 150 ° C. Use of a plastisol composition according to any one of claims 1 to 6 in the manufacture of automobiles, in particular for the protection of the underbody of vehicles, 2o as adhesives for bonnet lining, as threshold protection materials, as metal adhesives or as spot welding pastes. Use of the plastisol composition according to any one of claims 1 to 6 in the packaging industry as a sealant for Container closures or for sealing seams or as glue seams for cans. Use of a plastisol composition according to any one of claims 1 to 6 for coating textile materials, wallpaper or flooring 30 tiles. - 15 10. - 9 6 iL 2 c Claims ij 0150a 10 itacone, c) optionally other comonomers with crosslinking effect. 11. Use of a plastisol composition according to any one of claims 1 to 6 for the cladding of wheel rims, in particular for automobiles. Use of a plastisol composition according to any one of claims 1 to 6 for the production of floor coverings. Zastu