DE3310966C2 - - Google Patents

Description

The invention relates to a method for manufacturing a color-stabilized polyurethane-coated Shaped body made of polyvinyl chloride or a copolymer of vinyl chloride with by applying a dispersion or a latex of the polyurethane in water on the Surface of the molded body. In particular, the Invention creating a polyurethane coating from an aqueous dispersion on a polymer substrate, wherein the shaped body discolored at temperatures withstands from 100 to 150 ° C.

Generally, films made from aqueous polyurethane Dispersions with aging in the heat at temperatures up to discolored to about 150 ° C, but are at temperatures up to color stable at around 70 to 100 ° C. Are vinyl chloride polymers generally color stable, even at temperatures of 150 ° C over longer periods. If a vinyl chloride polymer with a polyurethane from an aqueous solution or dispersion is coated, however, the composite discolors Molded body at temperatures of only 70 ° C.

In US-PS 39 23 713 an organic is proposed Monoisocyanate, an antioxidant and an absorbent for UV radiation to a urethane adhesive for the Add plastic bonding to prevent yellowing to prevent when outgassing. This use reaches you certain degree of stability of the adhesive.  

In technology, it is required that a urethane that is considered Coating on a surface made of polyvinyl chloride or a vinyl chloride copolymer is applied, both itself as well as with regard to the substrate for a long time Use not discolored when the combination is high Temperature during and after the manufacturing process is subjected.

It is therefore a primary object of the invention, one polyurethane-coated molded body made of vinyl chloride polymer to create or copolymer, the discoloration poses no problem at temperatures up to about 150 ° C, using certain treated urethanes in aqueous dispersion that easily applied to a surface made of polyvinyl chloride or a vinyl chloride copolymer can be layered, this surface aesthetically is satisfactory.

This goal is achieved by a method according to claim 1 reached.

The connection that is selected from

• 1. a monoacid halide,
• 2. an acid anhydride,
• 3. a carbethoxy-cyclic imide

is added to an aqueous urethane latex according to the invention and the mixture becomes a surface Given polyvinyl chloride, making a with the Urethane coated or polyvinyl chloride composite body made of a vinyl chloride copolymer generated with the urethane coating, the is resistant to thermal discoloration.  

The compounds mentioned are those, the amine groups capping or blocking and making such connections which are effective in the invention. The mechanism which is the basis of the effect is not completely understandable however, it is believed that a function of Compounds is that amines of some kind, which are present in the polyurethane latex are capped.

According to one embodiment of the invention, a prepolymer soluble or dispersible in water Isocyanate end groups dispersed in water and with a Monoacid halide, mono-acid anhydride, carbethoxy-cyclic Imide or mixtures of these compounds are treated. The The latex product obtained is then applied to the surface of a Shaped body made of polyvinyl chloride or a vinyl chloride Copolymer coated and hardened thereon.

According to another embodiment, a prepolymer is used Isocyanate end groups dispersed in water and quickly less than stoichiometric amounts of a polyamine added as a chain extender and then the obtained Product with a mono acid halide, mono acid anhydride, Carbethoxy-cyclic imide or mixtures thereof treated. The latex obtained is applied to a surface made of polyvinyl chloride given and hardened on this surface, wherein a molded body made of the polymer with a color stabilized Urethane coating is obtained. Although the polyamine competes with the -NCO groups reacts with water and much faster than this if that Prepolymer with -NCO end groups is dispersed in water, some urethane with amine end groups is formed, regardless of to the quick addition of the amine chain extender.

The compounds useful in the present invention for include addition to the water dispersed polyurethane

• 1. a mono acid halide, preferably a mono acid chloride, such as p-toluenesulfonyl chloride, but also benzoyl chloride, Butyryl chloride, hexanoyl chloride and the like,
• 2. An acid anhydride, such as the anhydrides of mono acids, including Acetic anhydride, propionic anhydride, butyric anhydride and benzoic anhydride and
• 3. a carbethoxy-cyclic imide, especially the substituted ones Imides and most preferred, aryl monoimides, such as N-carbethoxyphthalimide.

The reaction product of a polyisocyanate is also included a monoalcohol to form a monoisocyanate. The compounds mentioned are in very small quantities from 1 to 5% by weight, even as low as 1 to 3% by weight on the weight of the polyurethane in latex, effective. Larger quantities do not appear to give any additional advantage.

The invention both the substrate made of polyvinyl chloride or a vinyl chloride copolymer as well layered polyurethane relatively thermally color stable. However, if the polyurethane is not treated according to the invention the coated molded body is not color-stable. It is actually surprising and unexpected that only certain capping compounds according to the present Invention for the formation of the color-stable composite molded body are effective.

Any polyisocyanate can be used to produce the polyurethanes will. Typical aromatic polyisocyanates are m-phenylene diisocyanate, p-phenylene diisocyanate, polymethylene polyphenyl isocyanate, 2,4-toluenediisocyanate, 2,6-toluenediisocyanate, Dianisidine diisocyanate, ditolylene diisocyanate, naphthalene 1,5-diisocyanate, diphenylene-4,4'-diisocyanate, such as xylylene 1,3-diisocyanate, bis (4-isocyanatophenyl) methane, 4,4'-  Diphenylpropane diisocyanate and aliphatic diisocyanates such as Isophorone diisocyanate, hexamethylene diisocyanate and 4,4 '- (isocyanatocyclohexyl) methane.

Preferred aromatic polyisocyanates according to the invention 2,4- and 2,6-toluenediisocyanates are needed and polyphenyl polyisocyanates with methylene bridges as compound mixtures, which have functionalities from 2 to about 4.

The polyhydroxy compounds or polyols can with substances be low or high molecular weight and generally have average hydroxyl numbers according to ASTM E-222-67, Method B, from between about 1000 and 10 and preferably between about 500 and 50. The term "polyol" means Substances that average two or more hydroxyl groups possess in every molecule.

The polyols include low molecular weight diols, triols and higher alcohols, lower amide-containing polyols Molecular weight and higher polymer polyols, such as polyester polyols, Polyether polyols and hydroxyl-containing acrylic acid interpolymers.

The low molecular weight diols, triols and higher alcohols, which are useful according to the invention are in themselves known. They have hydroxyl numbers of 200 or above, usually in the range of 1500 to 200. Such substances include aliphatic polyols, especially alkylene polyols with 2 to 18 carbon atoms. Examples are ethylene glycol, 1,4-butanediol, 1,6-hexanediol, cycloaliphatic polyols, such as 1,2- Cyclohexanediol, Cyclohexanedimethanol, and the higher alcohols include trimethylolpropane, dimethylolpropionic acid, Glycerol and oxyalkylated glycerol.  

If flexible and elastomeric properties are desired, should the partially reacted polymer with NCO groups preferably part of a higher polymeric polyol Molecular weight included. Such a polymeric polyol should be predominantly linear (i.e. trifunctional or higher functional components should be absent) to avoid gelling of the polymeric product obtained, and they should have a hydroxyl number of 200 or below, preferably within the range of about 150 to 30.

Any suitable polyalkylene ether polyol can be used including those with the following structural formula

wherein the substituent R is hydrogen or a lower alkyl group is, including mixed substituents, and n typically means 2 to 6 and m is a number from 2 to 100 or is higher. These include poly (oxytetramethylene) glycols, Poly (oxyethylene) glycols, polyoxypropylene glycol and that Reaction product of ethylene glycol with a mixture of Propylene oxide and ethylene oxide.

Polyether polyols which are produced by oxyalkylation are also useful of various polyols, e.g. B. glycols, such as Ethylene glycol, 1,6-hexanediol, bisphenol A and the like. Or higher polyols, such as trimethylolpropane, pentaerythritol and Like. Be formed. Polyols of higher functionality that can be used as indicated, e.g. B. by Oxyalkylation of compounds such as sorbitol or sucrose getting produced. A commonly used method of oxyalkylation  consists of reacting a polyol with a Alkylene oxide in the presence of an acidic or basic catalyst.

In addition to the poly (oxyalkylene) glycols, suitable polyvalent ones Polythioethers are used, e.g. B. the condensation product of thioglycol or the reaction product of one polyhydric alcohol as described above for the production of hydroxy Polyesters have been named, such as thioglycol or another suitable glycol.

Polyester polyols are preferred as the polymeric polyol component in carrying out the invention. The polyester polyols can by polyesterification of organic polycarboxylic acids or their anhydrides with organic polyols will. The polycarboxylic acids and are usually Polyols aliphatic or aromatic dibasic acids and diols.

Those commonly used to make the polyester Diols are alkylene glycols, such as ethylene glycol and butylene glycol, Neopentyl glycol and other glycols, such as the hydrogenated one Bisphenol A, cyclohexanediol, cyclohexanedimethanol, caprolactone diol (e.g. the reaction product of caprolactone and Ethylene glycol), hydroxyalkylated bisphenols, polyether glycols, e.g. B. poly (oxytetramethylene) glycol and the like. However are other diols of different types and as stated above Polyols of higher functionality can also be used. Such higher polyols can e.g. B. include trimethylolpropane, Trimethylolethane, pentaerythritol and the like, as well as higher molecular weight Polyols, such as those obtained by oxyalkylating low molecular weight Polyols can be obtained. An example of such high molecular weight polyols is the reaction product of 20 moles Ethylene oxide per mole of trimethylolpropane.  

The acid component of the polyester preferably consists of primarily from monomeric carboxylic acids or anhydrides 2 to 18 carbon atoms per molecule. To the acids that usable include phthalic acid, isophthalic acid, tetra- and hexa-, hydrophthalic acid, Adipic acid, azelaic acid, sebacic acid, maleic acid, Glutaric acid, chloro-diacid, tetrachlorophthalic acid and other dicarboxylic acids of different types. Larger amounts of one monobasic acid, such as benzoic acid, can be mixed with sucrose can be combined to effectively polyfunctional To produce sucrose benzoate. This polyfunctional material can then use various other ingredients and isocyanates are reacted to form polyurethanes with increased durability. Higher polycarboxylic acids, such as trimellitic acid and tricarballylic acid will. In the case of the acids mentioned above, the anhydrides can also be used such acids that form anhydrides instead of Acid can be used. Lower alkyl esters of Acids such as dimethyl glutarate can be used. It is preferred that the polyester is an aliphatic dicarboxylic acid contains at least as part of the acid component.

The amines used to extend the chain of the invention aqueous polyurethanes used can be used can be primary or secondary (with an H available) diamines or be polyamines, the radicals attached to the nitrogen atom are bound, saturated or unsaturated, aliphatic, alicyclic, aromatic, aromatic-substituted aliphatic, aliphatic-substituted aromatic or hetercyclic Leftovers can be. Mixed amines in which the Leftovers z. B. aromatic and aliphatic can be used will. Examples of suitable aliphatic and alicyclic Diamines are the following: ethylenediamine, 1,2- Propylene diamine, 1,8 methane diamine, isophorone diamine, propane 2,2-cyclohexylamine, methane-bis- (4-cyclohexylamine) and  

where x = 1 to 10.

Aromatic diamines such as phenylene diamines and toluene diamines can be used. Examples of the amines mentioned are o-phenylenediamine and p-tolylenediamine, N-alkyl and N-aryl derivatives the amines mentioned can be used, such as. B. N, N'-dimethyl-o-phenylenediamine, N, N'-di-p-tolyl-m-phenylenediamine and p-aminodiphenylamine.

Polynuclear aromatic diamines can be used where the aromatic rings are bonded are interconnected, e.g. B. 4,4'-biphenyldiamine, methylenedianiline and monochloromethylene dianiline.

As is known per se, the amount of polyamine can be up to 100% the equivalent amount to the NCO groups in the prepolymer are present, but it is preferred to be less to use as the stoichiometric amount. Excess Polyamine can be added, but serves no useful purpose in the scope of the invention.

Vinyl substrates useful in the present invention include the wide range of vinyl chloride polymers and copolymers with vinyl acetate or acrylic acid, e.g. B. vinylidene chloride and the like, as is known per se. Surprisingly found that polyvinyl chloride and vinyl chloride copolymer substrates, that weren't heat stabilized first, nevertheless by the urethane coating according to the invention were made color stable.

If the previously described coating on the polyvinyl chloride or vinyl chloride copolymer substrate is applied, with or without known stabilizers, such as those from  Cadmium / Barium type, there is no noticeable discoloration, and both the coating and the substrate remain color stable in heat aging as shown in the following examples becomes.

Example 1

There was polyhexanediol adipate with hydroxy end groups and a hydroxyl number of 112 in an amount of 199 g at 80 ° C. melted. There were 24.6 g of dimethylolpropionic acid and 152 g of 4,4'-di- (isocyanatocyclohexyl) methane added and the temperature was reduced to 60 ° C. 95.3 g of acetone were obtained and 18.6 g of triethylamine were added. The mixture was at Stirred at 65 ° C for 4 h and gave a prepolymer with 3.3% free NCO groups. The prepolymer was dispersed in 750 g of water and chain extended with 7.5 g of ethylenediamine.

• A) A sheet of dried film made from the the aforementioned dispersion had been poured after Do not age for 3 days at 100 ° C in a convection oven discolored.
• B) A sheet of white plasticized PVC, which is also after aging 5 days at 100 ° C in a convection oven not discolored was coated with the latex obtained and aged at 100 ° C. After 24 h the PVC became yellow and after It turned purple for 4 days.  
• C) The above latex was treated with 1.0% solution of Toluene sulfonyl chloride (3% by weight based on solid Polymer) treated at room temperature for 1 h and layered on the same PVC used in B). After aging 8 days at 100 ° C, none Discoloration noticed. A slight yellowing appeared only after 8 days at this temperature.

Example 2

Toluene diisocyanate (TDI) was partially mixed with methanol (molar ratio 1: 1) implemented, leaving a free NCO group free, which was able to react with amine end groups. After addition to urethane latex reduced according to Example 1 this product discolored the composite polyvinyl chloride body.

Example 3

Example 1 was repeated, replacing the toluenesulfonyl chloride 1% N-carbethoxyphthalimide solution was used. The treated urethane was on a copolymer of vinyl chloride and vinyl acetate piled up. That coated Substrate was tested at 100 ° C for 7 days. It was not significant Discoloration observed.  

Example 4

Example 1 was repeated, using 10 g of adipic acid hydrazide and 7.5 g of ethylenediamine to extend the chain of the dispersed Polyurethane were added. The latex obtained was with butyric anhydride instead of toluenesulfonyl chloride treated and layered on a PVC substrate. That coated composite material withstood the thermal Discoloration according to example 1.

Other known capping compounds, such as ethylene carbonate, Phenylchloroformate and butyrolactone, for example added to the latex of Example 1. After checking at 100 ° C for several days in each case Coating and the substrate (laminate) a discoloration.

In addition to the components mentioned, the mixtures contain optional components including the various Pigments commonly used in coatings this general group can be used. In addition various fillers, plasticizers, antioxidants, Means for regulating the flow behavior, surface-active Substances, cross-linking agents and other additives in many Cases are added.

The urethane mixtures mentioned can by any conventional method applied, including brushing, dipping, Flow coating, electrodeposition, electrostatic Syringes and the like, but they are most commonly sprayed on applied by air. The usual spraying technique and device for this are used. The coatings according to The invention can be used on virtually any vinyl substrate be applied. There can be many different embodiments  of the invention are carried out without To deviate inventive ideas and the scope of the invention, and the invention is not limited to particular embodiments limited.

Claims (5)

1. A process for producing a color-stabilized polyurethane-coated molded article made of vinyl chloride polymer or copolymer by applying a dispersion or a latex of the polyurethane in water to the surface of a molded article made of vinyl chloride polymer or copolymer and drying the coating on the surface of the molded article, characterized in that treating the dispersed polyurethane with a compound selected from the group consisting of a mono-acid halide, mono-acid anhydride and carbethoxy-cyclic imide. 2. The method according to claim 1, characterized in that the compound added in an amount of 1 to 3 % By weight, based on the latex weight, is used. 3. The method according to claim 1, characterized in that a carbethoxy monocyclic compound is added Imid used. 4. The method according to claim 1, characterized in that one p-toluenesulfonyl chloride used as the added compound. 5. Color-stabilized, polyurethane-coated moldings made of vinyl chloride polymer, contains according to claims 1 to 4.