Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-12-29
2002-08-13
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S742000, C524S609000, C524S612000, C526S227000, C526S344200
Reexamination Certificate
active
06433060
ABSTRACT:
The present invention relates to a process for obtaining polymers based on vinyl chloride which are capable of giving plastisols having specific properties. More particularly, the invention relates to a process of seeded microsuspension polymerisation of vinyl chloride with or without one or more copolymerisable monomers.
It is known to use plastisols prepared from polymers based on vinyl chloride in the manufacture of various articles, such as floor and wall coatings, plastified coated fabrics, and mastics.
In view of the vigorous competition, many studies have been carried out for the purpose either of attempting to find new applications for these plastisols or of improving their properties.
A further subject of numerous studies has been processes for manufacturing polymers based on vinyl chloride which are capable of giving plastisols having specific properties, thereby opening up the way to new applications.
Japanese Patent Application JP 62-231594 discloses a process for manufacturing polymers based on vinyl chloride which are capable of giving plastisols having low viscosity, good thermal stability and good resistance to water absorption. The essential feature of this process is the presence of hydrotalcite, which is introduced into the reaction medium before or during the initial phase of polymerisation of the vinyl chloride.
Moreover, a process for preparing vinyl chloride polymers which is capable of giving plastisols having a low initial viscosity, stability in the viscosity in the course of storage, and good degassing properties has been described in French Patent FR 2163573. That document teaches working in an aqueous medium under the action of organosoluble initiators and water-soluble reducing agents, in the presence of alkali metal salts of higher fatty acids containing 8 to 18 carbon atoms and at least one compound selected from the group (A) consisting of higher alcohols and higher fatty acids having 8 to 18 carbon atoms.
Comparative Example 5 of the document FR 2163573 shows that a polymerisation of vinyl chloride conducted in the absence of a compound from group (A) leads to highly viscous plastisols which are poorly suited to degassing and have poor transparency.
Apart from the documents mentioned above, the literature provides no processes for obtaining plastisols having a set of appropriate properties, given the difficulty of improving simultaneously two or more of their properties. Thus the resistance to water absorption is often sacrified for the benefit of thermal stability, or else good suitability to degassing at the expense of viscosity.
One aim of the present invention is to provide plastisols which lend themselves well to debubbling, or plastisols containing no air bubbles after kneading, while retaining or improving at least one of the following properties : thermal stability, resistance to discoloration, UV stability, transparency, rheology and hydrophobicity. The target plastisols are in particular those which lend themselves well to debubbling and have good thermal stability, those which lend themselves well to debubbling and have adequate hydrophobicity, and those which lend themselves well to debubbling and have good thermal stability and adequate hydrophobicity.
This aim is achieved in accordance with the present invention by a process of seeded microsuspension polymerisation of vinyl chloride with or without one or more polimerizable comonomers in an aqueous medium under the action of at least one organosoluble initiator, of at least one reducing agent selected from the group (S) consisting of alkali metal sulphoxylates, sulphites and metabisulphites, of at least one water-soluble metal salt selected from the group (M) consisting of salts of iron, copper, cobalt, nickel, zinc, titanium, vandium, manganese, chromium, cerium, of tin and of silver, in the presence of at least one alkali metal or ammonium salt of a fatty acid containing 8 to 22 carbon atoms.
The present invention firstly provides a process for obtaining latex containing polymer particles based on vinyl chloride, which consists in polymerising the corresponding monomer(s) in microsuspension in the presence of water, at least one water-soluble metal salt selected from the group (M), at least one alkali metal or ammonium salt of a fatty acid containing 8 to 22 carbon atoms, at least one reducing agent selected from the group (S), at least one seed polymer (P1) whose particles contain at least one organosoluble initiator and, if desired, at least one seed polymer (P2).
Microsuspension polymerisation, or polymerisation in microsuspension, means the polymerisation in the presence of organosoluble initiators of at least one monomer which is dispersed by means of mechanical energy in an aqueous medium containing an emulsifier as stabiliser to give a dispersion of particles whose average diameter is less than 5 &mgr;m.
Polymers based on vinyl chloride are the homopolymers and the copolymers, the latter containing at least 50% by weight of vinyl chloride and at least one monomer copolymerisable with vinyl chloride. The copolymerisable monomers are those generally employed in conventional techniques of copolymerising vinyl chloride. Mention may be made of vinyl esters of mono- and polycarboxylic acids, such as vinyl acetate, propionate and benzoate; unsaturated mono- and polycarboxylic acids, such as acrylic, methacrylic, maleic, fumaric and itaconic acid and their aliphatic, cycloaliphatic and aromatic esters, their amides, and their nitrites; vinyl halides and vinylidene halides; alkyl vinyl ethers; and olefins.
Preparation of the Seed Polymer (P1)
The seed polymer (P1) required for the polymerisation in accordance with the invention is prepared in accordance with conventional techniques of microsuspension polymerisation. It is present in the form of a dispersion of polymer particles whose average diameter is between 0.2 and 2 &mgr;m and, preferably, between 0.3 and 1 &mgr;m.
One means of preparing the polymer (P1) consists in employing water, vinyl chloride alone or in combination with one or more copolymerisable monomers, an organosoluble initiator and an anionic emulsifier alone or in combination with a non ionic emulsifier. The monomer or monomers are finely dispersed in water with the aid of a means of mechanical energy such as, for example, a colloid mill, high-speed pump, vibratory stirrer, ultrasound apparatus or high-pressure mixer disperser. The microsuspension obtained is then heated under autogenous pressure and with moderate stirring at a temperature which is generally between 30 and 65° C. Following the drop in pressure, the reaction is stopped and the unconverted monomer or monomers are outgassed.
The organosoluble initiators to be employed in the preparation of the polymer (P1) are represented by organic peroxides, such as diacyl peroxides (for example lauroyl, decanoyl or caproyl peroxides), tert-butyl diethylperacetate, dicetylhexyl percarbonate, diacetyl peroxide and dicetyl peroxocarbonate. The preferred initiators are those which are also insoluble in water.
The organosoluble initiator is selected such that its deployment in a reasonable amount makes it possible to obtain polymers (P1) containing between 1 and 10% by weight of this initiator for a preparation period of between 4 and 16 hours.
The proportion by mass of organosoluble initiator present in the particles of the polymer (P1) is advantageously between 1 and 4%.
The preferred organosoluble initiator is lauroyl peroxide.
Preparation of the Seed Polymer (P2)
The optional seed polymer (P2) is present in the form of a dispersion of polymer particles based on vinyl chloride whose average diameter is between 0.05 and 0.5 &mgr;m, and preferably between 0.08 and 0.2 &mgr;m.
This particle dispersion can be obtained by conventional techniques of emulsion polymerisation.
One means of preparing the polymer (P2) consists in employing water, vinyl chloride alone or in combination with a copolymerisable monomer, a water-soluble initiator and an anionic emulsifier with or without a non-ionic emulsifier.
The reaction mixt
Bonardi Christian
Bonnaud Bernard
Chippaux Andre
Peres Richard
Atofina
Cheung William K
Pennie & Edmonds LLP
Wu David W.
LandOfFree
Vinyl chloride-based polymers capable of giving plastisols... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vinyl chloride-based polymers capable of giving plastisols..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vinyl chloride-based polymers capable of giving plastisols... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2968628