COMPOSITION FOR PRODUCING TRANSPARENT POLYTHIOURETHANE BODIES

Abstract

The invention relates to a composition for producing transparent polythiourethane bodies containing or consisting of A) a polyisocyanate component containing at least one polyisocyanate with a functionality of isocyanate groups of at least 2 per molecule, B) a thiol component containing at least one polythiol with a functionality of thiol groups of at least two per molecule, in addition to optionally C) auxiliary agents and additives, the ratio of isocyanate groups to groups reactive in relation to isocyanates being 0.5:1 to 2.0:1. The composition is characterised in that the polyisocyanate of the polyisocyanate component A) is produced by a gas-phase phosgenation of aliphatic, cycloaliphatic, aromatic or araliphatic polyamines. The invention also relates to a method for producing transparent polythiourethane bodies by the conversion of a composition of this type, to polythiourethane bodies produced in this manner and to the use of polyisocyanates, produced by a gas-phase phosgenation of aliphatic, cycloaliphatic, aromatic or araliphatic polyamines, for producing transparent polythiourethane bodies.

Claims

1.-15. (canceled)

16. A composition for producing transparent polythiourethane articles comprising A) a polyisocyanate component containing at least one polyisocyanate having a functionality of isocyanate groups of at least 2 per molecule, B) a thiol component containing at least one polythiol having a functionality of thiol groups of at least 2 per molecule and optionally C) auxiliary and additive agents, wherein the ratio of isocyanate groups to isocyanate-reactive groups is 0.5:1 to 2.0:1, wherein the composition further contains D) at least one aromatic nitrile.

17. The composition as claimed in claim 16, wherein the composition contains 0.0025 to 10 wt/based on the entire composition of aromatic nitrile.

18. The composition as claimed in claim 16, wherein the nitrile contains at least one further functional group, in particular an isocyanate group.

19. The composition as claimed in claim 16, wherein the nitrile is selected from the group consisting of benzonitrile, 3-(isocyanatomethyl)benzonitrile, 4-(isocyanatomethyl)benzonitrile, 3-(chloromethyl)benzonitrile, 4-(chloromethyl)benzonitrile and mixtures thereof.

20. The composition as claimed in claim 16, wherein the polyisocyanate is selected from the group consisting of 1,3-bis(isocyanatomethyl)benzene (1,3-XDI), 1,4-bis(isocyanatomethyl)benzene (1,4-XDI), 2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-diisocyanatodicyclohexylmethane, 2,4-diisocyanatodicyclohexylmethane, 4,4-diisocyanatodicyclohexylmethane (H12-MDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI) and mixtures thereof.

21. The composition as claimed in claim 16, wherein the polyisocyanate is an aromatic polyisocyanate and the nitrile is derived from the same polyamine as the polyisocyanate.

22. The composition as claimed in claim 20, wherein the polyisocyanate is selected from 1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and the nitrile from 3-(isocyanatomethyl)benzonitrile and/or the polyisocyanate is selected from 1,4-bis(isocyanatomethyl)benzene (1,4-XDI) and the nitrile from 4-(isocyanatomethyl)benzonitrile.

23. The composition as claimed in claim 16, wherein the polythiol is selected from group consisting of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 2,5-bismercaptomethyl-1,4-dithiane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, trimethylolpropane tris(3-mercaptopropionate), trimethylolethane tris(2-mercaptoacetate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate) and mixtures thereof.

24. The composition as claimed in claim 16, wherein component C) is one or more of a catalyst, a surface-active agent, a UV stabilizer, an antioxidant, a fragrance, a mold release agent, a filler or a pigments.

25. The composition as claimed in claim 24, wherein the mold release agent is a phosphate ester.

26. The composition as claimed in claim 24, wherein the mold release agent is mono- and/or dialkoxyalkyl phosphates having 2 to 12 carbon atoms in the alkoxyalkyl radical and up to three ether groups per alkoxyalkyl radical.

27. A process for producing a transparent polythiourethane article comprising reacting a composition comprising A) a polyisocyanate component containing at least one polyisocyanate having a functionality of isocyanate groups of at least 2 per molecule, B) a thiol component containing at least one polythiol having a functionality of thiol groups of at least 2 per molecule and optionally C) auxiliary and additive agents, wherein the ratio of isocyanate groups to isocyanate-reactive groups is 0.5:1 to 2.0:1, wherein the composition further contains D) at least one aromatic nitrile.

28. A compact and transparent polythiourethane article obtained by reaction of the components of a composition as claimed in claim 16.

29. A mixture of a polyisocyanate having a functionality of isocyanate groups of at least 2 per molecule and at least one aromatic nitrile for producing compact transparent polythiourethane articles.

Description

EXAMPLES

[0109] FIG. 1 depicts a schematic diagram of a suitable plant for gas-phase phosgenation. This plant is particularly suitable for manufacturing 1,3-XDI and 1,4-XDI with contents of nitriles >0.1 wt % based on the manufactured isocyanate.

[0110] All percentages are based on weight, unless stated otherwise.

[0111] Measurement of the refractive indices and Abbe numbers was effected using an A. KRSS Optronic GmbH Model AR4D Abbe refractometer at 23 C. as per DIN EN ISO 489:1999-08.

[0112] Transmission and haze measurements as per ASTM D 1003 were performed with a Byk Haze-Gard Plus using standard light type D65 (defined in DIN 6173).

[0113] The chemicals used were employed without further pretreatment:

[0114] Tinuvin 571: alkylphenol-substituted benzotriazole (BASF)

[0115] Zelec UN: mixture of long-chain mono- and dialkyl phosphate (Steppan)

[0116] DBC: dibutyltin dichloride (Acros Organics)

[0117] DMPT: 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (Bruno Bock GmbH)

[0118] Performing the Phosgenation of 1,3-XDA

Example 1

[0119] In a plant for gas-phase phosgenation comprising an amine evaporation stage as per FIG. 1, a tubular reactor (L: 9350 mm, internal diameter 134.5 mm) having a coaxial nozzle arranged along the reactor axis (internal diameter 134.5 mm) and a downstream isocyanate condensation stage, 200 kg/h of 1,3-XDA were continuously evaporated at a pressure of 650 mbar abs. with introduction of a nitrogen stream of 10 kg/h, the temperature in the pumped circulation circuit (3200 kg/h) being kept at 150 C. by cooling in a heat exchanger (WT). 500 ppm Tinuvin 571 had previously been added to the pumped circulation circuit. The supply temperature to the evaporator (V) was 255 C., the entry temperature of the cooling medium into the heat exchanger (WT) was 40 C. and the average residence time of the 1,3-XDA in the pumped circulation circuit was 35 minutes. After exiting the evaporator the stream composed of gaseous 1,3-XDA and nitrogen was heated to 280 C. in a further heat exchanger and supplied to the reactor via the coaxial nozzle. Simultaneously and in parallel thereto, 750 kg/h of phosgene were heated to 310 C. and on the annular space left free by the nozzle likewise continuously supplied to the reactor in which the two reactant streams were mixed and brought to reaction. The velocity of the gas stream in the reactor was about 20 m/s and the velocity ratio of the amine/nitrogen stream to the phosgene stream was 8.8. The pressure at the vacuum pump was 600 mbar abs.

[0120] After an average residence time in the reactor of 0.48 seconds the gas stream containing the reaction product 1,3-XDI was cooled by injection cooling with monochlorobenzene and condensed, the temperature of the liquid phase in the quench being about 90 C. The content of 3-chlormethylbenzyl isocyanate determined by gas chromatography was 0.4% based on the sum of 1,3-XDI and 3-ClXI. The reaction mixture was then freed of HCl and phosgene and worked up by distillation. The yield of 1,3-XDI was 95% of theory.

Example 2

[0121] In the abovedescribed plant 160 kg/h of 1,3-XDA were analogously evaporated at a pressure of 500 mbar abs. with introduction of a nitrogen stream of 4 kg/h, the temperature in the pumped circulation circuit (3200 kg/h) being kept at 150 C. by cooling in a heat exchanger (WT). 500 ppm Tinuvin 571 had previously been added to the pumped circulation circuit. The supply temperature to the evaporator (V) was 240 C., the entry temperature of the cooling medium into the heat exchanger (WT) was 40 C. and the average residence time of the 1,3-XDA in the pumped circulation circuit was 43 minutes. The stream composed of gaseous 1,3-XDA and nitrogen was heated to 280 C. in a further heat exchanger and supplied to the reactor via the coaxial nozzle. Simultaneously and in parallel thereto, 500 kg/h of phosgene were heated to 310 C. and on the annular space left free by the nozzle likewise continuously supplied to the reactor in which the two reactant streams were mixed and brought to reaction. The velocity of the gas stream in the reactor was about 20 m/s and the velocity ratio of the amine stream to the phosgene stream was 8.8. After an average residence time in the reactor of 0.46 seconds the gas stream containing the reaction product 1,3-XDI was cooled by injection cooling with monochlorobenzene and condensed, the temperature of the liquid phase in the quench being about 90 C.

[0122] The content of 3-chlormethylbenzyl isocyanate determined by gas chromatography was 0.3% based on the sum of 1,3-XDI and 1.3-ClXI. The reaction mixture was then freed of HCl and phosgene and worked up by distillation. The yield of 1,3-XDI was 92% of theory.

[0123] Production of XDI Manufactured by Liquid-Phase Phosgenation for Comparison

Example 3 (Comparative)

[0124] With stirring and cooling a solution of 5 parts by weight of 1,3-XDA in 50 parts by weight of monochlorobenzene was metered into a solution of 20 parts by weight of phosgene in 25 parts by weight of monochlorobenzene at 0-10 C. and on completion of the addition the mixture was allowed to reach room temperature. The temperature was subsequently increased to reflux with introduction of phosgene according to gas evolution and phosgenation was continued until the solution eventually became clear. Once the clear point had been reached (about 4-5 h) phosgenation was continued for a further 30 minutes. Phosgene introduction was then terminated and the mixture was refluxed with introduction of nitrogen until phosgene was no longer detectable in the offgas.

[0125] The reaction mixture was then worked up by distillation to obtain XDI as a colorless liquid having a boiling point of 130 C./0.2 mbar. The yield of 1,3-XDI was 80% of theory.

Example 4

[0126] 2 kg of the XDI obtained in example 2 were fractionally distilled through a column. The first 500 g were discarded as forerun and 1 kg of colorless 1,3-XDI was obtained as the main fraction. This main fraction was admixed with 1.4 g of Zelec UN (Steppan) at room temperature and left to stand for 24 h. The HC content of the sample after distillation, measured as per ASTM specification D4663-98, was 105 ppm.

[0127] The content of 3-isocyanatomethylbenzonitrile was determined by dissolving 1 g of 1,3-XDI in 100 ml of acetonitrile. 100 l of this solution were mixed with 900 l of a di-ethylamine solution (0.2 g of diethylamine in 100 ml of acetonitrile) and stored at 65 C. for 30 minutes prior to HPLC-MS measurement. Purity was determined by integration of the areas of the signals in the UV. It was assumed that all compounds show the same UV absorption and that no compounds without a UV absorption are present in the samples. A further assumption was that no degradation reactions take place during measurement.

[0128] The following program was chosen for HPLC-MS measurement:

[0129] Synapt G2-S HR-MS, ACQUITY UPLC (Waters) QS. No.: 02634

[0130] UV: PDA (Total Absorbance Chromatogram)

[0131] Column: Kinetex 1002.1 mm_1.7 m

[0132] Column temperature: 30 C.

[0133] The mobile phase consisted of:

[0134] Solvent: A) water+0.05% formic acid

[0135] B) acetonitrile+0.05% formic acid

[0136] Flow rate: 0.5 ml/min

[0137] Gradient: t0/5% B_t0.5/5% B_t6/100% B_t7/100% B_t7.1/5% B_t8/5% B

[0138] The sample was found to contain 98.4% 1,3-XDI and 0.7% 3-isocyanatomethylbenzonitrile.

Example 5

[0139] 2 kg of the XDI obtained in example 3 were fractionally distilled through a column. The first 800 g were discarded as forerun and 700 g of colorless 1,3-XDI were obtained as the main fraction. This main fraction was admixed with 0.98 g of Zelec UN at room temperature and left to stand for 24 h. The HC content of the sample after distillation measured as per ASTM specification D4663-98 was 108 ppm.

[0140] Analogously to example 4, purity determination by HPLC was performed. No 3-isocyanatomethylbenzonitrile was found in the course of this. The proportion of 1,3-XDI was 95.4%.

[0141] Production of Polythiourethane Spectacle Glasses:

Example 6

[0142] A casting mold was first prepared by clamping together two glass shell molds (85 mm diameter, internal radius 88 mm, Shamir Insight, Inc., IL) with a gap of 8 mm and a plastic sealing ring to form a casting cavity. The mold gap is 8 mm at each point of the lens.

[0143] The casting system was produced as follows:

[0144] In a flask, 0.002 g of dibutyltin dichloride (DBC) were dissolved in 94.59 g of 1,3-XDI from example 4 and the mixture was evacuated at 10 mbar for 30 minutes. 90.00 g of DMPT (4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane) were then added into the flask and the final mixture was stirred and degassed at 10 mbar for 30 minutes. This mixture was then filtered through a 5 m filter, drawn into a syringe and the casting mold was completely filled therewith.

[0145] The filled casting mold was cured in a drying cabinet with the temperature profile: 15 hours at 65 C.; 2 hours at 100 C. and a further 2 hours at 120 C. The casting mold was then cooled to room temperature and, after complete cooling, first the sleeve and then the two glass articles were manually removed.

[0146] A spectacle glass blank that was completely clear, transparent and free from cloudiness was obtained in this way.

[0147] Transmission was 90.3% for standard light type D65, haze was 2.1. The refractive index nE was 1.67 at 23 C.

Example 7

[0148] Analogously to example 6 a spectacle glass blank was produced using 1,3-XDI from example 5. This spectacle glass blank was completely cloudy, transmission was only 29.7%, haze was 100.