Novel phthalate-free isocyanurate compositions and uses thereof

Abstract

The present invention provides novel, highly effective, low monomer content, low viscosity, low volatility compositions comprised of isocyanurates containing isocyanate groups and phthalate-free plasticizers, which impart improved adhesion when used as adhesion promoters, as well as coating compositions based on plasticized PVC and coated substrates.

Description

[Technical field]

[0001] The present invention relates to the technical field of adhesion promoters, in particular adhesion promoters for coating compositions based on plasticized PVC, and provides phthalate-free, low monomer content, low viscosity and low volatility compositions with excellent suitability as adhesion promoters. [Background technology]

[0002] It is known that it is possible to improve the adhesive properties of plasticized PVC to substrates by adding to it adhesion promoters containing isocyanate groups. Such an improvement in adhesive properties is important, for example, when it is desired to produce synthetic fiber materials with a PVC coating. The adhesion promoters used are preferably isocyanurates, which contain isocyanate groups and can be produced from diisocyanates by oligomerization, in particular trimerization. The diisocyanates used for this purpose are TDIs (usually mixtures of isomeric diisocyanatotoluenes, mainly consisting of 2,4-diisocyanatotoluene (2,4-TDI) and 2,6-diisocyanatotoluene (2,6-TDI)), which mixtures are readily available on the market. They can be easily processed to isocyanurates containing almost entirely isocyanate groups. Workplace and product safety, as well as EU regulations, require nearly complete conversion, and for this reason the residual diisocyanate content in the adhesion promoter composition is kept below 0.5% by weight. Less preferred is diisocyanatodiphenylmethane (MDI), which has similar good availability but is less prone to trimerization than TDI, resulting in undesirably high residual diisocyanate content. MDI-based isocyanurates containing isocyanate groups also exhibit low solubility and have a tendency to crystallize.

[0003] Isocyanurates containing isocyanate groups Isocyanurates containing isocyanate groups are easy to handle as adhesion promoters, especially when used in the form of a solution in a plasticizer. Isocyanurates containing isocyanate groups derived from TDI are preferably prepared in the plasticizer used as a solvent. These adhesion promoters and adhesion promoter compositions containing plasticizers, their preparation and their use are described, for example, in US Pat. No. 5,399,623 (US Pat. No. 5,499,623) or US Pat. No. 5,499,633.

[0004] Plasticizers and Plasticized PVC For the purposes of this invention, a plasticizer is typically an organic substance that has no or only low volatility and does not bond covalently to PVC, but reduces its glass transition temperature. By mixing with a plasticizer, PVC (which is itself rigid and brittle) is transformed into a flexible, tough material, which those skilled in the art call plasticized or soft PVC. At room temperature, the plasticized PVC is usually a flexible solid. Suitable plasticizers are known to those skilled in the art. Examples of typical plasticizers include esters of phthalic acid, terephthalic acid, sebacic acid, trimellitic acid, alkanesulfonic acid, citric acid or benzoic acid with alcohols. The amount of such plasticizers present in the plasticized PVC is high, usually ranging from 10% to more than 50% by weight of the total mass of the plasticized PVC. Under improper use conditions, the plasticizer can migrate onto or into adjacent materials. The use of plasticized PVC therefore poses the risk of human and environmental contamination by the plasticizers. In view of these problems, there have been recent demands for the plasticizers used to be non-hazardous to humans and non-biocumulative.

[0005] Short-Chain Phthalates as Plasticizers The REACH regulation applicable in the European Union places the plasticizers di(2-ethylhexyl) phthalate, dibutyl phthalate, and benzyl butyl phthalate on the list of Substances of Very High Concern (SVHC). Furthermore, the plasticizers diisononyl phthalate, diisodecyl phthalate, and di-n-octyl phthalate can no longer be used in toys and baby products that may be placed in a child's mouth. In light of these restrictions, which some consumers consider to be unclear and worrying, many manufacturers are generally moving towards avoiding all phthalate-containing plasticizers and their isomers in the production of plasticized PVC. Thus, there is a demand for phthalate-free plasticizers that can achieve the same performance levels as phthalate-based plasticizers in terms of processability and in-use performance.

[0006] Phthalate-Free Plasticizers In the context of the present invention, the expression "phthalate-free plasticizer" is used for plasticizers which contain less than 1.0% by weight, preferably less than 0.5% by weight, particularly preferably less than 0.1% by weight and particularly preferably 0% by weight of dialkyl phthalates, based on the plasticizer content.

[0007] Phthalate-free adhesion promoter composition By avoiding phthalate-containing plasticizers, adhesion promoter compositions containing plasticizers are now required, especially in sensitive applications, for example in contact with the skin.Therefore, there is a strong demand for adhesion promoter compositions that are completely free of phthalates, but that nevertheless have good adhesion properties comparable to those of the phthalate-containing adhesion promoter compositions from the prior art.In the context of the present invention, the expression "phthalate-free adhesion promoter compositions" is used for adhesion promoter compositions that contain less than 1.0% by weight, preferably less than 0.5% by weight, particularly preferably less than 0.1% by weight, particularly preferably 0% by weight of dialkyl phthalates, based on their total mass.

[0008] Further requirements are that such adhesion promoter compositions be colorless and transparent, be completely free of solids or precipitates, be completely free of highly volatile components, i.e. organic compounds with a boiling point between 0° C. and 100° C., and, for good processability, have a viscosity at 23° C. of less than 30,000 mPas, preferably less than 10,000 mPas, particularly preferably less than 5000 mPas. The residual content of monomeric diisocyanates should be less than 0.8% by weight, preferably less than 0.6% by weight, particularly preferably 0.5% by weight or less. A comprehensive list of these product performances has not been described in the prior art to date.

[0009] For example, the adhesion promoter compositions based on diisononyl phthalate described in US Pat. No. 4,993,363 are not very suitable for sensitive applications. US Pat. No. 4,293,363 and US Pat. No. 4,293,375 claim that isocyanurates containing isocyanate groups based on TDI and suitable as adhesion promoters can be prepared in any solvent, including phthalate-free plasticizers. However, in practice this is not true. Experiments carried out by the present inventors have shown that any selected phthalate-free plasticizer will definitely not result in an adhesion promoter composition that satisfies all the above requirements. This also applies to the plasticizers based on alkylsulfonic esters of phenols (ASE) and sold under the trademark Mesamoll® described in US Pat. No. 4,293,363 describe solutions of isocyanurates containing isocyanate groups suitable as adhesion promoters, but they are prepared from MDI. These solutions are unsuitable for the reasons mentioned above. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] DE 2419016 A1 [Patent Document 2] GB Patent Application Publication No. 1455701A [Patent Document 3] International Publication No. 2011 / 095569 Brochure [Patent Document 4] International Publication No. 2005 / 70984A1 Brochure [Patent Document 5] DE 2551634 A1 [Patent Document 6] European Patent Application Publication No. 1378529A1 [Patent Document 7] German Patent No. 102007034977 [Patent Document 8] DE 3041732 A1 Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention was therefore to provide suitable compositions of isocyanurates containing isocyanate groups as adhesion promoters, which, while containing phthalate-free plasticizers, achieve in terms of their mechanical properties, such as adhesive strength, the level of the phthalate-containing adhesion promoters described in WO 2005 / 70984 A1. The isocyanurates containing isocyanate groups are based on isomeric mixtures of TDI, which are available on an industrially large scale. The compositions are transparent and almost colourless, their viscosity at 23° C. is less than 30,000 mPas, preferably less than 10,000 mPas, particularly preferably less than 5000 mPas, and the content of free TDI (all isomers) is less than 0.8% by weight, preferably less than 0.6% by weight, particularly preferably 0.5% by weight or less. The volatility of the plasticizer used should not be higher than that of isononyl benzoate.

[0012] Volatility of plasticizers The volatility of the plasticizers used must not be less favorable than that of isononyl benzoate (INB), which, in terms of volatility, is accepted worldwide for its performance as a carrier for isocyanurates and as an active substance in adhesion promoters. However, a higher volatility is undesirable. The volatility of the substances is determined here by thermogravimetric analysis (TGA). [Means for solving the problem]

[0013] The object is achieved, and the invention therefore provides, compositions comprising: a) isocyanurates containing isocyanate groups, and b) benzyl alkyl adipates, Here, the weight ratio of a) to b) is in the range of 1:1 to 1:8, preferably a) to b) is in the range of 1:1.2 to 1:4, particularly preferably 1:1.5 to 1:2.5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In a preferred embodiment, the benzyl alkyl adipate has a branched or unbranched C alkyl group. 6 ~C 16 It bears an alkyl group, preferably an unbranched or branched octyl group, most preferably an isooctyl group.

[0015] Very particular preference is given to using benzyl octyl adipate as component b).

[0016] In a preferred embodiment of the invention, the composition comprises 20% to 35% by weight of an isocyanurate containing isocyanate groups and 80% to 65% by weight of benzyloctyl adipate.

[0017] In yet another preferred embodiment, the composition comprises up to 50% by weight, preferably 0.1% to 40% by weight, based on the total weight of the composition, of a diluent, preferably from the group comprising alkyl acetates, preferably butyl acetate, ethyl acetate, propyl acetate, N-alkylpyrrolidone, N-octylpyrrolidone, N-decylpyrrolidone, DMF, acetone, alkyl benzoates, preferably benzyl benzoate, paraffin, white oil and aliphatic compounds with low aromatic content, and mixtures of these substances.

[0018] Isocyanurates containing isocyanate groups which can advantageously be used as component a) can be obtained by trimerizing a mixture of isomeric diisocyanatotoluenes, including 2,4-diisocyanatotoluene and 2,6-diisocyanatotoluene.

[0019] The isocyanurates which contain isocyanate groups and are preferably used as component a) can be obtained by trimerizing a mixture of 65% to 95% by weight of 2,4-diisocyanatotoluene and 5% to 35% by weight of 2,6-diisocyanatotoluene, the weight percentages being based on the total amount of diisocyanatotoluene, respectively.

[0020] The preparation of component a) can be achieved by trimerizing a diisocyanate mixture, for example by known processes of the type described in WO 2005 / 70984 A1.

[0021] The trimerization is preferably carried out in the presence of a plasticizer, component b).

[0022] The present invention further provides a process for preparing the inventive composition, in which a diisocyanate is trimerized in the presence of a benzyl alkyl adipate b) to give an isocyanurate a) containing isocyanate groups.

[0023] The trimerization reaction is typically carried out at a temperature in the range of 40 to 140° C., preferably 40 to 80° C. The trimerization reaction is stopped when the content of monomeric diisocyanate in the reaction mixture is 0.8% by weight, preferably 0.6% by weight, and most preferably 0.5% by weight or less.

[0024] The above-mentioned termination reaction can be carried out, for example, by pyrolyzing the catalyst or by adding a reaction terminator to completely or partially deactivate the catalyst. As the reaction terminator, a protonic acid, an acyl chloride, or a methylated compound can be used. It is particularly preferable to use an alkyl phosphate, in particular dibutyl phosphate, or methyl toluenesulfonate. When a reaction terminator is used, the amount of the reaction terminator is typically 0.22% to 4% by weight, preferably 0.1% to 2% by weight, and particularly preferably 0.2% to 1% by weight, based on the total amount of the diisocyanate used. Then, the reaction product typically contains 3% to 7% by weight, preferably 4.5% to 6% of isocyanate groups.

[0025] In a preferred embodiment, the diisocyanate used in the process of the invention is a diisocyanatotoluene, particularly preferably a mixture consisting essentially of 2,4-TDI and 2,6-TDI, which is available on an industrially large scale. The mixture is a mixture of isomeric diisocyanatotoluenes, which comprises 65% to 95% by weight of 2,4-diisocyanatotoluene and 5% to 35% by weight of 2,6-diisocyanatotoluene, produced by catalytic action. The isomeric mixture of TDI particularly preferably comprises 15% to 25% by weight of 2,6-TDI together with 75% to 85% by weight of 2,4-TDI in the mixture. An example of such an isomeric mixture of TDI which is particularly preferably used is the product Desmodur® T80, which is commercially available from Covestro AG.

[0026] In the preparation of component a), it is possible to use catalysts which act to initiate and accelerate the trimerization reaction and selectively incorporate TDI at relatively high temperatures. These catalysts have phenolic OH groups and N,N-dialkylaminomethyl groups (alkyl: C1-C3 alkyl chains and / or alkylene chains with 1-18 carbon atoms, optionally interrupted by oxygen or sulfur) attached to aromatic systems.

[0027] These groups may be distributed over several molecules or may be located on one or several aromatic rings.The compounds used as catalyst systems are preferably such that they contain, in one molecule, not only hydroxy groups but also aminomethyl groups.

[0028] It is particularly preferred to use systems in which a C1-C3 dialkylaminomethyl group is in the ortho position relative to the aromatic hydroxy group.

[0029] The synthesis of Mannich bases suitable as catalysts is described, for example, in DE-A-25 51 634 and WO-A-2005 / 70984. The Mannich bases preferably used are based on phenyl, p-isononylphenol or bisphenol A, which can be obtained, for example, by reacting dimethylamine with formaldehyde according to DE-A2 452 531 or Synth.Commun.,(1986),16,1401-9. Particularly preferred are Mannich bases based on phenol or bisphenol A.

[0030] The catalysts used are used as pure substances or in solution, preferably in small portions multiple times or successively.

[0031] The compositions of the present invention are clear, colorless or almost colorless liquids that are surprisingly stable on storage, with no tendency to discolor or crystallize, or to form precipitates or phase separate, even after several weeks of storage. Before and after storage, they are further characterized by an extremely low free TDI (i.e., monomeric diisocyanatotoluene) content, which is a particular advantage of the compositions of the present invention, since this toxicologically suspect diisocyanate has a relatively low boiling point.

[0032] In the comparative examples 1 to 6 presented below, it is therefore not only clear that the objective underlying the present invention is not achievable with any selected phthalate-free plasticizer, but it is furthermore demonstrated that the present invention also provides a process which makes it possible to advantageously create a combination of a plasticizer and an isocyanurate containing isocyanate groups, which, in the form of an adhesion promoter composition, gives the required properties.

[0033] Uses of the compositions of the present invention The compositions of the invention are particularly suitable as adhesion promoters for coatings made of plasticized PVC or as adhesion-promoting additives for PVC plastisols. As the skilled artisan will understand, the expression "PVC plastisols" refers to liquid dispersions of PVC in plasticizers, which gel when heated to relatively high temperatures, for example, and can therefore be used to produce plasticized PVC. The compositions of the invention can be particularly advantageously used as adhesion promoters between substrates made of synthetic fibers, such as polyamide or polyester fibers, which have groups reactive with isocyanate groups, and PVC plastisols or flexible PVC melts. It is self-evident that the solutions of the invention can also be used to improve the adhesion of plasticized PVC onto planar substrates, for example onto foils.

[0034] The compositions of the invention are therefore particularly suitable as adhesion promoters for coating compositions based on plasticized PVC. For the purposes of the present invention, the expression "coating composition based on plasticized PVC" encompasses not only coating compositions comprising plastisols, but also coating compositions which, when applied to a substrate, take the form of a composition comprising molten flexible PVC, the former being preferred here.

[0035] Particularly suitable substrates to be coated are textiles, such as woven fabrics made of natural, synthetic or glass fibers. Particularly suitable synthetic fibers are polyamide and polyester fibers. Furthermore, leather can also be used as substrate.

[0036] The composition of the invention can be used for the manufacture of substrates having a coating that comprises or consists of plasticized PVC. If the coating does not consist of plasticized PVC, it typically comprises at least 50% by weight, preferably at least 75% by weight, particularly preferably 90% to 99% by weight, of it, together with further substances recognized by the skilled artisan as customary in PVC coatings. The composition of the invention can be applied, for example, to the substrate coated by the printing, doctor knife, screening or spraying method, or by the dipping method. Depending on the needs of the product to be produced, one or more adhesion promoter-free PVC layers are then applied to the surface of the substrate thus treated, for example in the form of a plastisol or by extrusion coating or hot melt roll coating, or by lamination. It is particularly preferred that the composition of the invention is further added to the PVC plastisol before it is applied.

[0037] The compositions of the invention are usually used in an amount such that 0.5% to 40% by weight, preferably 2% to 15% by weight, of isocyanurate containing isocyanate groups is present, based on the plasticizer-free PVC of the coating composition. However, the solutions of the invention can also be used in any other desired amount suitable for the respective field of application.

[0038] Irrespective of the application method used, the creation of the finished layer, i.e. the reaction of the isocyanate groups of the adhesion promoter with the substrate and the gelling of the PVC layer, is accomplished in a conventional manner at relatively high temperatures, between 110 and 210° C., depending on the composition of the PVC layer.

[0039] The present invention further provides coatings and coated substrates for textiles or fabrics, which can be obtained using the adhesion promoter composition described above.The composition of the present invention is suitable as an adhesion promoter for coating compositions based on plasticized PVC and therefore for the production of coatings that contain or consist of plasticized PVC, i.e. in particular for the production of tarpaulins, billboards, air-supported structures and other textile structures, flexible containers, tent roofs, awnings, protective clothing, conveyor belts, flocked carpets or foamed synthetic leather.

[0040] The compositions of the invention have particularly good suitability as adhesion-promoting additives for coating substrates which have groups reactive with isocyanate groups, in particular for coating yarns, mats and woven fabrics made of polyester or polyamide fibers. EXAMPLES

[0041] Examples of the present invention and comparative examples Unless otherwise specified, all parts and percentages are by weight.

[0042] Parameter measurement The parameters determined for the reaction products were the viscosity at 23°C (VT550 rotational viscometer, Haake GmbH, Karlsruhe) and the content of free TDI (gas chromatography, Hewlett Packard 5890, according to DIN ISO 55956). The isocyanate content was determined according to EN ISO 11909. Mettler Toledo TGA / DSC3+ SF / 1100 / 189, T = room temperature to 400°C, 10°C / min, N 2 was used to generate the TGA curves.

[0043] Starting materials for the inventive and comparative examples Desmodur® T80: isomer mixture of TDI consisting of 80% by weight of 2,4-TDI and 20% by weight of 2,6-TDI, manufactured by Covestro AG. Vestinol® 9 DINP: Diisononyl phthalate, manufactured by Evonik. Adimoll® DB: dibutyl adipate, manufactured by Lanxess Deutschland GmbH. Adimoll® DO: dioctyl adipate, manufactured by Lanxess Deutschland GmbH. Adimoll® BO: benzyl octyl adipate, manufactured by Lanxess Deutschland GmbH. Benzoflex® 2088: A mixture of diethylene glycol dibenzoate, triethylene glycol dibenzoate and dipropylene glycol dibenzoate manufactured by Velsicol Chemical Corp. Mesamoll® II: Phenyl alkanesulfonate, manufactured by Lanxess Deutschland GmbH. Catalyst: DABCO TMR 30 (2,4,6-tris(dimethylaminoethyl)phenol) Reaction stopper: dibutyl phosphate

[0044] [Table 1]

[0045] Table 1 shows that at normal processing temperatures for PVC plastisols, dibutyl adipate (DBA) has already evaporated very substantially, which is unacceptable for reasons of environmental protection and workplace safety. Furthermore, blistering may occur in the PVC layer, which is also highly undesirable.

[0046] Comparative Example 1: (non-invention) DINP 180 parts by weight of Desmodur® T80 were trimerized in 378 parts by weight of Vestinol® 9 DINP with 1.6 parts by weight of catalyst at 55° C. The reaction was stopped after 72 hours by adding 2.6 parts by weight of a reaction terminator and stirring was continued for 3 hours at 60-70° C. A clear, colorless solution was obtained with an isocyanate content of 5.53% by weight, a viscosity at 23° C. of 41,400 mPas and a content of free TDI of 0.14% by weight.

[0047] Comparative Example 2: (non-invention) DBA First, the volatility of dibutyl adipate was determined by TGA (see Table 1).

[0048] This material was found to evaporate almost completely at normal PVC-processing temperatures of 180-210°C, which would cause blistering in the PVC layer and is therefore highly undesirable, so further testing was not carried out.

[0049] Comparative Example 3: (Not of the Invention) Ethylene Glycol Dibenzoate and Propylene Glycol Dibenzoate 180 parts by weight of Desmodur® T80 were trimerized in 415 parts by weight of Benzoflex® 2088 with 0.7 parts by weight of catalyst at 50° C. The reaction was stopped after 84 hours by adding 1.7 parts by weight of a reaction terminator and stirring was continued for 3 hours at 60-70° C. A clear, colorless solution was obtained with an isocyanate content of 4.8% by weight, a viscosity at 23° C. of more than 200,000 mPas and a content of free TDI of 1.09% by weight.

[0050] Comparative Example 4: (non-invention) 2.9 parts Mesamoll® II catalyst 180 parts by weight of Desmodur® T80 were trimerized in 504 parts by weight of Mesamoll® II with 2.9 parts by weight of catalyst at 55° C. The reaction was stopped after 72 hours by adding 4.7 parts by weight of a reaction terminator and stirring was continued for 3 hours at 60-70° C. A clear yellowish solution was obtained with an isocyanate content of 4.8% by weight, a viscosity at 23° C. of more than 11,600 mPas and a content of free TDI of 0.25% by weight.

[0051] Comparative Example 5: (non-invention) 1.5 parts Mesamoll® II catalyst 180 parts by weight of Desmodur® T80 were trimerized in 378 parts by weight of Mesamoll® II with 1.5 parts by weight of catalyst at 55° C. The reaction was stopped after 72 hours by adding 2.6 parts by weight of a reaction terminator and stirring was continued for 3 hours at 60-70° C. A clear yellowish solution was obtained with an isocyanate content of 5.31% by weight, a viscosity at 23° C. of more than 300,000 mPas and a content of free TDI of 0.15% by weight.

[0052] Comparative Example 6: (Not of the Invention) Dioctyl Adipate 180 parts by weight of Desmodur® T80 were trimerized in 534 parts by weight of Adimoll DO with 2.5 parts by weight of catalyst at 70° C. The reaction was stopped after 5 hours by adding 5 parts by weight of reaction terminator and stirring was continued for 1 hour at 60-70° C. No clear solution was obtained. After some time a precipitate formed. The reaction product was therefore unusable and no further analysis was carried out.

[0053] Comparative Example 1 corresponds to Example 2 of EP 1 711 546 A1 and makes it possible to compare the properties of the adhesion promoter composition according to the invention with the prior art. Comparative Examples 4 and 5 show that increasing the amount of catalyst does not automatically result in the reaction product according to the invention.

[0054] As non-inventive comparative examples 1 to 6 further show, the choice of plasticizer has a decisive influence on the trimerization result. Thus, using phthalate-free plasticizers as described in the prior art, it is not possible to obtain the desired combination of properties, or this can only be achieved as long as the concentration of TDI trimer does not exceed about 27% by weight. All of these adhesion promoters either have a high viscosity that makes further processing impossible, or their concentration of TDI trimer is too low to provide sufficient adhesive strength.

[0055] Example 1 of the present invention: benzyl octyl adipate (=-K93) 180 parts by weight of Desmodur® T80 were trimerized in 414 parts by weight of Adimoll® BO with 1.6 parts by weight of catalyst at 70° C. The reaction was stopped after 12 hours by adding 3.2 parts by weight of a reaction terminator and stirring was continued for 1 hour at 60-70° C. A clear, colorless solution was obtained with an isocyanate content of 5.3% by weight, a viscosity of 1924 mPas at 23° C. and a content of free TDI of 0.5% by weight.

[0056] Performance test and test results: PVC-plastisol / adhesion promoter coatings were applied to woven polyester fabrics in a test system simulating industrial conditions. The adhesive strength of the coatings was then determined on standardized test specimens. For this, a doctor system was used to coat woven polyester fabrics with adhesive coatings containing adhesion promoters. The coatings were gelled in an oven before being tested. In the test for adhesive strength, two test specimens were placed on top of each other (PVC side to PVC side), pressed at 180°C with low pressure and tested in a tensile tester.

[0057] Test equipment: Scale: Minimum accuracy 0.1g Stirrer: High speed stirrer shaft Mathis Labcoater oven (manufactured by Mathis AG (Zuerich)) Ametec LR5Kplus tensile testing machine Polyester woven fabric: Polyester 1100dtex L9 / 9Z60 standard woven fabric

[0058] For this test, a sample of woven fabric measuring approximately 40 x 25 cm was used.

[0059] Composition of PVC plastisol: 70 parts PVC; Vestolit® B 7021 Ultra paste PVC; manufactured by Vestolit GmbH, Marl; 30 parts PVC; Vestolit® E 7031 paste PVC; manufactured by Vestolit GmbH, Marl; 33 parts Mesamoll® ASEP manufactured by Lanxess Deutschland GmbH; 33 parts of Vestinol® 9 DINP plasticizer manufactured by Evonik Oxeno GmbH (Marl); 10 parts Durcal® 5 chalk from Omya GmbH, Koeln; 2.5 parts Baerostab® UBZ 780 RF stabilizer manufactured by Baerlocher GmbH, Berlin; 1.5 parts Kronos® 2220 titanium dioxide; available from Kronos Titan GmbH, Leverkusen.

[0060] Test specimen: Adhesive coating approx. 140g / m 2 140℃ / 2min

[0061] The specimens were pressed, coated and then glued together, pregelled at 140°C and heated at 180°C for 2 minutes. Dimensions: Width 5cm x Length (weft direction) 25cm Tested using an Ametec LR5Kplus tensile testing machine

[0062] To prepare the PVC plastisol, the starting materials listed above under "Composition of the PVC plastisol" were mixed in a mixer (Drais) under vacuum by stirring at maximum rotation speed with water cooling for 2.5 hours.

[0063] Tensile test: The samples were then used to measure their adhesion strength using a Lloyd M5K tensile tester. The adhesion strength values ​​thus obtained indicate the force (units: Newton) required to peel 5 cm of the coating from the carrier fabric (peel test, strength is expressed in units of N / 5 cm in the tables). The values ​​given in the tables were determined by averaging at least three separate measurements.

[0064] Comparative Examples and Examples of the Invention As is evident from the measurement results of Example 1 of the present invention, when the phthalate-free composition of the present invention is used as an adhesion promoter, higher adhesion strength values ​​are obtained than those achieved with the prior art phthalate-containing composition (Comparative Example 1). The adhesion promoters from Comparative Examples 3, 5 and 6 are even less suitable for processing because they have excessive viscosity or produce precipitation. The compositions of Comparative Examples 4 and 5 also have an undesirable yellowish coloration. Another unexpected finding is that among the adipate type substances, only the benzyloctyl adipate of the present invention showed unexpectedly good effectiveness, while the other two reaction products from this type of substance both showed precipitation or were too volatile.

[0065] [Table 2]

Claims

1. a) an isocyanurate containing isocyanate groups, and b) benzyl alkyl adipates, Including, An adhesion promoter for plasticized polyvinyl chloride based coating compositions, wherein the weight ratio of a) to b) ranges from 1:1 to 1:

8.

2. The benzyl alkyl adipate has a branched or unbranched C ６ ~C １６ The adhesion promoter of claim 1 having an alkyl group.

3. 3. The adhesion promoter of claim 1 or 2, wherein the isocyanurate containing isocyanate groups is obtainable by trimerizing a mixture of isomeric diisocyanatotoluenes comprising 2,4-diisocyanatotoluene and 2,6-diisocyanatotoluene.

4. 4. The adhesion promoter of any one of claims 1 to 3, wherein the isocyanurate containing isocyanate groups is obtainable by trimerizing a mixture of 65% to 95% by weight of 2,4-diisocyanatotoluene and 5% to 35% by weight of 2,6-diisocyanatotoluene, each of said weight percentages being based on the total amount of diisocyanatotoluene.

5. The adhesion promoter of any one of claims 1 to 4, comprising up to 50% by weight of a diluent, based on the total weight of the adhesion promoter.

6. Use of the adhesion promoter of a coating composition based on plasticized polyvinyl chloride according to any one of claims 1 to 5.

7. The use according to claim 6, wherein the coating composition comprises at least one PVC plastisol.

8. 8. Use according to claim 6 or 7 for producing a substrate having a coating comprising or consisting of plasticized polyvinyl chloride.

9. 9. The use according to claim 8, wherein the substrate to be coated is a tarpaulin, a billboard, an air-supported structure and other textile structures, a flexible container, a tent roof, an awning, a protective garment, a conveyor belt, a flocked carpet, or a foamed synthetic leather.

10. 10. The use according to claim 8 or 9, wherein the substrate is a textile, a woven fabric, or leather.

11. 11. The use according to claim 10, wherein the woven fabric is a woven polyester fabric or a woven polyamide fabric.

12. A process for producing the adhesion promoter according to any one of claims 1 to 5, comprising trimerizing a diisocyanate in the presence of said benzyl alkyl adipate b) to obtain said isocyanurate a) comprising isocyanate groups.

13. 13. The process of claim 12, wherein the trimerization reaction is carried out at a temperature range of 40 to 140° C. and is stopped when the content of the diisocyanate used in the reaction mixture is 0.8 wt % or less.

14. 14. The process according to claim 12 or 13, wherein the diisocyanate used is a mixture of isomeric diisocyanatotoluenes comprising 2,4-diisocyanatotoluene and 2,6-diisocyanatotoluene.

15. A coating composition comprising the adhesion promoter of any one of claims 1 to 5 and at least one PVC plastisol.

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