FR2523991A1 - POLYVINYL CHLORIDE SURFACES COATED WITH POLYURETHANES AND PROCESS FOR THEIR PREPARATION - Google Patents

Abstract

THE SURFACE HAS BEEN COATED WITH AN AQUEOUS LATEX OF POLYURETHANE TREATED WITH A COMPOUND SELECTED IN THE GROUP CONSISTING ESSENTIALLY OF MONOACID HALIDES, MONOACID ANHYDRIDES, CYCLIC CARBETHOXYIMIDES AND MONOISOCYANATES.

Description

The present invention relates to polyvinyl chloride surfaces

  or of a copolymer of vinyl chloride coated with polyurethanes and to a process for their preparation More particularly, the present invention relates to the fact of applying to polymer surfaces an aqueous coating based on polyurethanes in which the whole resists tarnishing at temperatures of 100 to 1500 C. Generally, the films applied using

  aqueous dispersions of polyurethanes tend to change

  shade from aging to heat at temperatures

  erasures of up to about 1500 C, but have a completely stable coloring at temperatures up to about 70 to 1000 C On the other hand, vinyl chloride polymers generally have a stable coloring, even in prolonged exposure to temperatures of 1500 C However, when applying a polymer of

  vinyl chloride a coating of a solution or disper-

  aqueous polyurethane, the composite material

  coated takes on parasitic colorings at temperatures

  relatively low erasures, for example even at 70 ° C.

  In U.S. Patent No. 3,923,713, we

  suggests adding an organic monoisocyanate, an anti

  oxidant and an ultraviolet light absorber at a

  urethane adhesive for bonding plas-

  ticks to prevent gas yellowing These additions give the adhesive a certain level of stability. We would like in the industry to be able to apply

  on a surface of polyvinyl chloride or a copoly-

  mother of vinyl chloride a urethane coating without prolonged use or exposure to high temperatures during the manufacturing process

  and after manufacture, the coating or the support undergone

  a tarnishing or parasitic coloring.

  Thus, the invention relates firstly to a surface of polyvinyl chloride or of a vinyl chloride copolymer coated with a urethane and which does not

  does not give rise to parasitic colorings at temperatures

  erasures of up to approximately 150 ° C. The invention also includes a method for applying a coating of a polyurethane latex to a surface of polyvinyl chloride or of a copolymer.

vinyl chloride.

  The invention also includes aqueous dispersions of urethanes which can be applied directly as a coating on a polyvinyl chloride surface.

  or a copolymer of vinyl chloride, with

  Acceptable practical and aesthetic conditions.

  In general, the invention resides in the addition of a compound chosen from: (1) mono acid halides, (2) acid anhydrides, (3) cyclic carbethoxyimides, and (4) monoisocyanates

  to an aqueous urethane latex that is applied to an overlay

  side of polyvinyl chloride or a copolymer of

  vinyl chloride, in order to obtain a surface of chloro

  polyvinyl or vinyl chloride copolymer coated with a urethane and which resists colorations caused by heat The compounds listed above are amine blocking agents and constitute the compounds which are effective in the present invention. their action is not fully understood, but it is considered that a function of these compounds lies in the blocking of amines possibly present in the latex

polyurethane.

  The invention therefore also includes a method for forming the surface of a vinyl chloride polymer.

  coated with urethane and resistant to para-

  sités, process characterized in that a water-soluble or dispersible isocyanate prepolymer with isocyanate end groups is dispersed in water and treated with a monoacid halide, a monoacid anhydride, a monoisocyanate, a cyclic carbethyoxyimide or a mixture of such compounds This latex is then applied as a coating

  on a surface of polyvinyl chloride or a copoly-

  mother of vinyl chloride on which it is hardened. In another aspect, the invention relates to a method for forming a polyvinyl chloride surface.

  coated with urethane and resistant to parasitic coloring

  This process is characterized in that a prepolymer with isocyanate end groups is dispersed in water.

  and we quickly add a defect, compared to the quan-

  theoreticality, of a polyamine serving as an extension agent

  gement of the chains, then the product obtained is treated with a monoacid halide, a monoacid anhydride, a cyclic carbethoxyimide, a monoisocyanate or a mixture

  such compounds The final latex is applied to an

  face of polyvinyl chloride and hardened on this surface, thereby forming a polymer composite material

  coated with urethane and stable to parasitic coloring.

  Even though polyamine reacts with NCO groups a lot

  faster than the water it is in contact with

  When the prepolymer with NCO end groups is dispersed in water, a urethane with amine end groups is formed even when the functional amine

  chain extender was added quickly.

  Among the compounds suitable for use in the invention for the addition to the polyurethane dispersed in water, there will be mentioned (1) a monoacid halide, preferably a monoacid chloride such as p-toluene-sulfonyl chloride , but also benzyole chloride, butyryl chloride, hexanoyl chloride and

  analogous chlorides; (2) an acid anhydride, e.g.

  ple a monoacid anhydride, including acetic anhydride, propionic anhydride, butyric anhydride and benzoic anhydride; (3) a cyclic carbethoxyimide, in particular substituted imides and preferably aryl monoimides such as N-carbethoxyphthalimide; and (4) a monoisocyanate, alkyl isocyanate or aryl isocyanate, for example phenyl isocyanate, isocyanate

  p-chlorophenyl, cyclohexyl isocyanate, iso-

  Octadecyl cyanate and the analogous compounds Mention will also be made of the reaction product of a polyisocyanate with a monoalcohol giving a monoisocyanate These compounds are effective in very small proportions ranging from approximately 1 to 5% by weight and being able to go down to 1 at 3% in

  weight relative to the polyurethane contained in the latex.

  Higher proportions do not appear to provide

an added benefit.

  According to the invention, both the support of polyvinyl chloride or of a copolymer of vinyl chloride and the polyurethane applied as a coating are relatively resistant to colorations caused by heating. However, when the polyurethane is not treated as described above, the coated article is not stable in coloring It is in fact quite surprising and unexpected that only the blocking compounds described here are effective in the composite assembly

  with stable coloring according to the invention.

  To prepare polyurethanes, any polyisocyanate can be used. Among the polyisocyanates

  suitable aromatics, we will mention m-phenylene-

  diisocyanate, p-phenylene diisocyanate, polymethylene-

  polyphenylisocyanates, 2,4-toluene diisocyanate, 2,6-toluenediisocyanate, dianisidine diisocyanate, ditoluylene diisocyanate, naphthalene-1,5-diisocyanate,

  4,4 'diphenylene-diisocyanate, 1,3-xylylene

  diisocyanate, bis- (4-isocyanatophenyl) -methane,

  bis- (3-methyl-4-isocyanatophenyl) -methane, 4,4 '-

  diphenylpropane diisocyanate; and diisocyanates ali-

  phatics such as isophorone diisocyanate, hexamethylene-

  diisocyanate and 4,4 '- (isocyanatocyclohexyl) -methane. Preferred aromatic polyisocyanates

  in the practice of the invention are 2,4 and 2,6-

  toluene diisocyanate and mixtures of polyphenylpoly-

  isocyanates with methylene bridges which have functionalities

about 2 to 4.

  The polyhydroxy compounds or polyols can consist of substances with low molecular weight or with high molecular weight and generally have average hydroxyl numbers of approximately 1000 to 10 and preferably of approximately 500 to 50, the determination being made according to the

  procedure B of the American standard ASTM E-222-67.

  The term "polyols" applies to substances which have

  on average two or more hydroxy groups per molecule.

  Polyols include diols, triols and higher low molecular weight alcohols, low molecular weight polyols containing amide groups and

  higher polymer polyols such as polyester-

  polyols, polyether polyols and interpolymers

  acrylics containing hydroxy groups.

  The diols, triols and higher alcohols with low molecular weight which can be used in the invention are known compounds They have hydroxyl numbers

  200 or more, usually ranging from 200 to 1,500.

  Among these substances, there may be mentioned aliphatic polyols, in particular C 2 -C 18 alkylene polyols. As particular examples, mention will be made of ethylene glycol,

  1,4-butane diol, 1,6-hexane-diol; cyclol polyols

  aliphatics such as 1,2-cyclohexane-diol, cyclo-

  hexane-dimethanol and, among the higher alcohols, mention may be made of trimethylol-propane, dimethylolpropionic acid,

  glycerol and oxyalkylated glycerol.

  When looking for flexible and elastomeric products, the polymer having partially reacted NCO groups must preferably contain, at least in part, a high molecular weight polymer polyol. Such a polymer polyol must be mainly linear.

  (i.e. it must be free from tri-

  functional or higher functionality) if gelation of the polymer product obtained is to be avoided, and must have a hydroxyl number of 200 or less,

preferably from 150 to 30 approximately.

  Any suitable polyalkylene ether polyol can be used, including those which correspond to the following structural formula: t H OH m in which the symbol R represents hydrogen or a lower alkyl group or mixture of such substituents, and N a commonly a value of 2 to 6, and m a value of 2 to 100 or even more.

  poly- (oxytetramethylene) -glycols, poly- (oxyethylene) -

  glycols, polyoxycropylene glycols and the reaction product of ethylene glycol with a mixture of

propylene and ethylene oxide.

  It is also possible to use the polyether polyols formed by oxyalkylation of various polyols, for example glycols such as ethylene glycol, 1,6hexane diol,

  Bisphenol A and analogous glycols or higher polyols

  laughers such as trimethylol-propane, pentaerythritol and analogous polyols. It is possible to prepare usable polyols with higher functionality, for example in

  subjecting oxyalkylation of compounds such as sor-

  bitol or sucrose A oxyalkylation technique

  rante consists in reacting a polyol with an oxide

  alkylene in the presence of an acidic or basic catalyst.

  In addition to the poly (oxyalkylene) glycols, it is possible to

  use any suitable polyhydric polythioether

  required, for example the condensation product of thioglycol or the reaction product of a polyol as described in the present application for the preparation of hydroxylated polyesters, with thioglycol or another

any suitable glycol.

  The polyester polyols are the components

  polymer polyols preferred in the practice of the invention.

  The polyester polyols can be prepared by polyester.

  rification of polycarboxylic organic acids or

  their anhydrides by organic polyols Usually-

  Polycarboxylic acids and polyols are also

  dibasic acids and aliphatic or aromatic diols.

  The diols usually used in the preparation of polyester are inter alia alkylene glycols such as

  ethylene glycol and butylene glycol, neopen glycol

  tylic and other glycols such as Bisphenol A hydro-

  gene, cyclohexane-diol, cyclohexane-dimethanol, caprolactonediol (for example the reaction product of caprolactone and ethylene glycol), bisphenols

  hydroxyalkylated, polyether glycols, for example a poly-

  (oxytetramethylene) -glycol or the like.

  However, it is also possible to use other diols of various types and, as already mentioned, polyols with a higher functionality. Among these higher polyols,

  for example, trimethylolpropane, trimethyl

  lethane, pentaerythritol and the like and high molecular weight polyols such as those

  obtained by oxyalkylation of low molecular weight polyols

  The reaction product of 20 moles of ethylene oxide on 1 mole of trimethylolpropane constitutes a

  example of such a high molecular weight polyol.

  The acid component of polyester consists of

  preferably mainly in mono- carboxylic acids

  Mothers or anhydrides of such C 2 -C 18 acids azelalque acid, sebacic acid, maleic acid, glutaric acid, chlorendic acid,

  tetrachlorophthalic acid, and other dicarbo-acids

  xylics of various types Large proportions of a monobasic acid such as benzolic acid can be combined with sucrose in order to prepare a benzoate of

  effective polyfunctional sucrose This poly-

  functional can then be reacted with other various components and isocyanates to form polyurethanes with improved durability.

  can also use higher polycarboxylic acids

  laughing like trimellitic acid and tricarbal acid-

  lylic (when speaking of acids, it will be understood that the corresponding anhydrides may be used in place of these acids). It is also possible to use the lower alkyl esters of acids such as dimethyl glutarate. Preferably, the polyester comprises , at least in part of the acid component, a dicarboxylic acid

aliphatic.

  The amines which can be used for the extension of the chains of the aqueous polyurethanes according to the invention can consist of primary or secondary diamines or polyamines (containing a free hydrogen atom) in which the radicals are fixed on the nitrogen atoms

  can be saturated or unsaturated, aliphatic, ali-

  cyclic, aromatic, aliphatic substituted by aro-

  matic, aromatic, aliphatic or hetero substituted

  cyclic Mixed amines can also be used in which the radicals are, for example, aromatic and aliphatic. As particular examples of suitable aliphatic and alicyclic diamines, mention will be made

  ethylene diamine, 1,2-propylene diamine, 1,8-

  menthane diamine; isophorone diamine, propane-2,2-

  cyclohexylamine, methane-bis- (4-cyclohexylamine) and the compound of formula CH 3

H 2 NH 2

2 N H CH 2 0) CH NH 2

CH 3

where x = 1 to 10.

  Aromatic diamines such as

  that the phenylene diamines and the toluene diamines Com-

  Examples of these amines are o-phenylene diamine and ptolylene diamine. N-alkylated and N-arylated derivatives of these amines can be used, for example the

  N, N'-dimethyl-o-phenylene diamine, N, N'-di-p-tolyl-m-

  phenylene diamine and p-aminodiphenylamine.

  Poly- aromatic diamines can be used

  cyclic in which the aromatic nuclei are

  connected by a valence link, and for example the 4,4 '-

  biphenyl diamine, methylene dianiline and mono-

  chloromethylene dianiline. According to known practice, the amount of polyamine can represent up to the equivalent of 100% of the NCO groups present in the prepolymer, but it is preferred to use a defect relative to the theoretical amount. An excess of polyamine can be added, but this does not brings none

advantage in the invention.

  The vinyl supports suitable in the present invention comprise the wide range of polymers of vinyl chloride and copolymers of this compound with vinyl acetate or acrylic acid for example or also vinylidene chloride and analogous compounds well known in the art. industry It has been surprisingly found that supports made of polyvinyl chloride and copolymers of vinyl chloride which had not been heat stabilized beforehand were nevertheless made stable to parasitic coloring by the urethane coating.

according to the invention.

  When this coating is applied to the support of polyvinyl chloride or of vinyl chloride copolymer, with or without known stabilizers such as stabilizers of the cadmium / barium type for example, there is no appreciable parasitic coloring and the coating as the support remain stable in color during heat aging, as we can

  see it in the examples which follow and which illus-

  trent the invention without however limiting its scope; in these examples, the part and% indications

  by weight unless otherwise stated.

Example 1

  199 g of a polyadipate of hexane-diol with hydroxy end groups are melted at 800 ° C., OH number 112.

  24.6 g of dimethylolpropionic acid and 152 g of 4.4 '-di-

  (isocyanatocyclohexyl) -methane and the temperature is lowered

  at 600 ° C. 95.3 g of acetone and 18.6 g of tri- are introduced.

  ethylamine The mixture is stirred at 650 ° C. for 4 hours, thus forming a prepolymer with 3.3% of free NCO. This prepolymer is dispersed in 750 g of water and subjected

  chain extension using 7.5 g of ethylene-

  diamine. A A sheet of dry film cast from the above dispersion does not take color in

  5 days aging at 100 C in a convection oven

  tion. B A sheet of white plasticized polyvinyl chloride also does not color during aging -35 of 5 days at 100 ° C in a convection oven; a coating of the above latex is applied to this sheet and it is subjected to aging at 1000 ° C. After 24 hours, the polyvinyl chloride has taken on a yellow coloration and

  after 4 days a purple color.

  C The above latex is treated with 9.4 g of phenyl isocyanate (Ph NCO) (2.3% relative to the solid polymer) at room temperature for 1 hour and then applied as a coating on the same polyvinyl chloride. used

  in B above There is no parasitic coloring

  keep silent on aging for 5 days at 1000 C. It appears a slight yellowing after only 7 days at the same temperature.

Example 2

  A latex identical to that of Example 1 is applied as a coating on light brown polyvinyl chloride and subjected to aging for 7 days at 1000 C. The light coloration becomes very dark When the latex is treated as described in the example 1 per 1.0% of p-toluenesulfonyl chloride (instead of Ph NCO), no color change is observed in 8 days at 1000 C.

Example 3

  Toluene diisocyanate (TDI) is reacted in part with methanol at a molar ratio of 1: 1 so as to leave a free NCO group capable of reacting with the terminal amino groups When added to the urethane latex of example 1 this product prevents parasitic coloring of the vinyl composite assembly

as effectively as Ph NCO.

Example 4

  The operation of Example 1 is repeated, replacing the Ph NCO with 1% of Ncarbethoxy-phthalimide. The treated urethane is applied as a coating on a copolymer of vinyl chloride and vinyl acetate. The coated support is subjected to 7 days aging at 1000 C.

  No appreciable coloring is observed.

Example 5

  The operation of Example 1 is repeated but the polyurethane in dispersion with chain extension is subjected to the addition of 10 g of dihydrazide of adipic acid and 7.5 g of ethylene diamine The latex obtained is treated with butyric anhydride replacing phenyl isocyanate and applied as a coating on a polyvinyl chloride support The composite assembly resists

  heat stains as in Example 1.

  Other compounds were added to the latex of Example 1

  placed known blockers such as ethylene carbonate, phenyl chloroformate and butyrolactone for example After exposure for several days at 1000 C, in each case there is a coloration at the same time

  coating and support (composite assembly).

  In addition to the components mentioned above, the compositions usually contain optional components, including any of the various pigments commonly used for coatings of this general class. In addition, in many cases, it is possible to

  add fillers, plasticizers, anti

  oxidants, viscosity control agents, surfactants, crosslinkers and other additives

analogs of various types.

  The urethane compositions according to the invention can be applied by any suitable techniques, including by brush, by immersion, by

  continuous plating, by electrospray

  static and by analogous techniques but the most

  often they are applied with an air pistol.

  Usual spraying techniques and equipment are used. The coatings of the present invention can be applied to practically all substrates.

vinyl.

  It is clear that the invention is in no way limited to the preferred embodiments described above by way of examples and that a person skilled in the art can make it possible.

  modifications without departing from its framework.

Claims (7)

  1 Surface of polyvinyl chloride or a   vinyl chloride copolymer coated with a polyurethane-   ne and stable to parasitic coloring, polyurethane-   ne and polyvinyl chloride or chloride copolymer   each being resistant to parasitic coloring   keep silent at temperatures above about 1000 C   but taking parasitic colorations at temperatures   tures of around 100 ° C when combined, characteristic   terized in that: the surface of polyvinyl chloride or of vinyl chloride copolymer carries a coating, hardened on said surface, applied from an aqueous latex of polyurethane, said latex having been treated with a compound chosen from the group consisting essentially of mono acid halides, mono acid anhydrides,   cyclic carbethoxyimides and monoisocyanates.   2 coated surface according to claim 1,   characterized in that said compound is present in pro-   portion of about 1 to 3% of the weight of the latex.   3 coated surface according to claim 1,   characterized in that said compound is a monoisocyanate.   4 coated surface according to claim 1,   characterized in that said compound is N-carbethoxy- phthalimide.   Coated surface according to claim 1, characterized in that said compound is p-toluene-sulfonyl chloride. 6 A method for preparing the coated surface according to claim 1, characterized in that: a) an aqueous dispersion or aqueous latex of the polyurethane is prepared, b) the dispersion of polyurethane obtained in a) is treated with a compound chosen from the group consisting of in monoacid halides, monoacid anhydrides, cyclic carbethoxyimides and monoisocyanates, c) the product obtained in step b) is applied to the surface of the polymer and d) the coating is dried on said surface, thus forming a coated product colored polyurethane stable.   7 Method according to claim 6, characterized in that the compound b) is present in proportion to 1 at 3% of the weight of the latex.   8 Method according to claim 6, characterized in that the compound of stage b) is a monocyclic carbethoxyimide. 9 Method according to claim 6, characterized   in that the compound of step b) is a monoisocyanate.   10 Method according to claim 6, characterized in that the compound of stage b) is p-toluene-sulfonyl chloride.