Rigid Foam Prepared from the Same

TECHNICAL FIELD

The present invention relates to an isocyanate composition comprising a toluene diisocyanate residue , which can be used for preparing a polyurethane rigid foam having favorable insulation properties and compression strength . The present invention also relates to a polyurethane rigid foam prepared from said isocyanate composition .

BACKGROUD

Toluene diisocyanate (TDI ) are usually prepared by reacting toluene diamine (TDA) and phosgene and then purifying the obtained crude product via distillation . In practice , there exists a large amount of high-boiling distillation residues during the distillation process of the crude product of toluene diisocyanate (TDI ) . These residues are toxic and difficult to dispose ; thus disposal of these residues leads to a serious problem in industry, which is not only uneconomical , but also poses a safety risk . Therefore , it is a key process of producing TDI how to deal with and utilize these residues .

These distillation residues are usually treated by a method of incineration , wherein the toxic exhaust gases require additional recycling and processing . CN 1064074A discloses a method of reducing the content of hydrolysable chlorides in toluene diisocyanate (TDI ) , in particular in its distillation residues , and polymer made by processing the residues .

SUMMARY OF THE INVENTION The present invention provides an isocyanate composition, comprising : al) a toluene diisocyanate residue , wherein the toluene diisocyanate residue is selected from the distillation residue of toluene diisocyanate prepared by phosgene method, and wherein the toluene diisocyanate residue has a NCO content of 5-45 wt . % , based on the total weight of the toluene diisocyanate residue ; and a2 ) diphenyl methane diisocyanate , poly (diphenyl methane diisocyanate ) or a combination thereof .

In one embodiment of the present invention, the isocyanate composition has a NCO content of 30-40 wt . % , based on the total weight of the isocyanate composition .

In a preferred embodiment of the present invention, the toluene diisocyanate residue is selected from the distillation residue of toluene diisocyanate prepared by phosgene method in gas phase .

In another preferred embodiment of the present invention, the toluene diisocyanate residue has a content of 15-40 wt . % , based on the total weight of the isocyanate composition .

In still another preferred embodiment of the present invention, the toluene diisocyanate residue has a content of 20-30 wt.%, based on the total weight of the isocyanate composition .

The present invention also relates to a polyurethane rigid foam, wherein the polyurethane rigid foam is prepared from the above-mentioned isocyanate composition .

DETAINED DESCRIPTION

I . Isocyanate composition The present invention provides an isocyanate composition, comprising : al) a toluene diisocyanate residue , wherein the toluene diisocyanate residue is selected from the distillation residue of toluene diisocyanate prepared by phosgene method, and wherein the toluene diisocyanate residue has a NCO content of 5-45 wt . % , based on the total weight of the toluene diisocyanate residue ; and a2 ) diphenyl methane diisocyanate , poly (diphenyl methane diisocyanate ) or a combination thereof .

In one embodiment of the present invention, the isocyanate composition has a NCO content of 30-40 wt.%, based on the total weight of the isocyanate composition .

In one embodiment of the present invention, the isocyanate composition has a viscosity of 350-1100 mPa · s , preferably 450-1050 mPa · s and more preferably 550-950 mPa · s .

The toluene diisocyanate residue in the isocyanate composition has a content of 15-40 wt.%, preferably 20-30 wt.%, based on the total weight of the isocyanate composition .

In one embodiment of the present invention, the toluene diisocyanate residue is selected from the distillation residue of toluene diisocyanate prepared by phosgene method . The well-known phosgene method for preparing toluene diisocyanate generally consists of four steps :

(1) the reaction of toluene and nitric acid to form dinitro-toluene (DNT) ;

(2 ) the reaction of DNT and hydrogen to form toluene diamine (TDA) ;

(3 ) the reaction of TDA and phosgene to form toluene diisocyanate (TDI) ;

(4 ) purification of TDI by distillation .

The toluene diisocyanate residue used in the present invention is obtained in step (4 ) of purification by distillation, wherein the toluene diisocyanate residue has a NCO content of 5-45 wt . % , preferably 10-39 wt . % , more preferably 25-38 wt . % , based on the total weight of the toluene diisocyanate residues .

In a preferred embodiment of the invention, the toluene diisocyanate residue is selected from the distillation residue of toluene diisocyanate prepared by phosgene method in gas phase . Gas-phase phosgene method is characterized in that in said step (3 ) , TDA and phosgene react in gas phase , preferably at a temperature of 200-600 , to obtain the toluene diisocyanate . Isocyanate composition further comprises diphenyl methane diisocyanate (MDI ) , poly (diphenyl methane diisocyanate) (PMDI) or a combination thereof , with a content of 60-85% , preferably 70 -85% , based on the total weight of the isocyanate composition . In one embodiment of the present invention, the polyisocyanate composition may also comprise other organic polyisocyanates , such as aliphatic , alicyclic and aromatic diisocyanate (s) and/or polyisocyanate (s) . Examples of suitable organic polyisocyanates used in the present invention include , but are not limited to, 1 , 4-butylene diisocyanate , pentane-1, 5-diisocyanate, hexamethylene diisocyanate (HDI ) , isophorone diisocyanate ( IPDI ) , 2,2,4- and/or

2,4, 4 -trimethylhexamethylene diisocyanate , bis (4 , 4 ' - isocyanato-cyclohexyl ) methane or mixtures thereof with other isomers , 1 , 4 -cyclohexylene diisocyanate , 1, 4-phenylene diisocyanate, 1, 5-naphthalene diisocyanate, 1,3- and/or 1 , 4 -tetramethylxylylene diisocyanate (TMXDI ) ,

I , 3 -xylylene diisocyanate (XDI ) .

II . Polyurethane rigid foam

The present invention also provides a polyurethane rigid foam prepared from the above-mentioned isocyanate composition . The polyurethane rigid foam system provided by the present invention, preferably a conventional block foam and a plywood, has good insulation properties and compressive strength . In one embodiment of the present invention, the composition used for preparing the polyurethane rigid foam also comprises an isocyanate-reactive component . The isocyanate- reactive component may comprise one or more polyether and/or polyester polyol ( s ) having a hydroxy1 number of 150-1200 mgKOH/g and a content of 75-95 wt . % , based on the total weight of the isocyanate-reactive component .

The polyether polyols used in the present invention can be prepared by known processes . For example , it can be obtained by the reaction of alkylene oxide and an initiator in the presence of a catalyst . The catalyst is , preferably but not limited to , alkali hydroxides , alkal i alkoxides , ant imony pentachloride , boron fluoride etherate , or a mixture thereof . The alkylene oxide is , preferably but not 1 imited to, tetrahydrofuran, ethylene oxide , propylene oxide, 1 , 2 -butylene oxide , 2 , 3 -butylene oxide , styrene oxide , or a mixture thereof ; in particular preferably ethylene oxide and/or propylene oxide . The initiator is , preferably but not limited to, a polyhydroxy or polyamine compound . The polyhydroxy compound is , preferably but not limited to, water , ethylene glycol , 1 , 2 -propanediol , 1 , 3 -propanediol , diethylene glycol , trimethylolpropane , glycerol , bisphenol A, bisphenol S or a mixture thereof . The polyamine compound is , preferably but not limited to , ethylene diamine , propylene diamine , butylene diamine , hexamethylene diamine , diethylenetriamine , tolylenediamine or a mixture thereof . The polyether polyol has a funct ional ity of 2 -8 , preferably 2 -5.

The polyester polyol is obtained by the reaction of a dicarboxylic acid or dicarboxylic acid anhydride with a polyol . The dicarboxylic acid is preferably, but not limited to , an aliphatic carboxyl ic acid containing 2 to 12 carbon atoms , for example , succinic acid, malonic acid , glutaric acid, adipic acid, suberic acid, azelaic acid, capric acid, dodecylic acid, maleic acid, fumaric acid, phthal ic acid, isophthal ic acid, terephthalic acid, and a mixture thereof . The dicarboxylic acid anhydride is preferably, but not limited to, phthalic anhydride , tetrachlorophthalic anhydride , ma1eic anhydride , and a mixture thereof . The polyol is preferably, but not limited to , ethylene glycol , diethylene glycol , 1 , 2 -propanediol , 1 , 3 -propanediol , dipropylene glycol , methyl -1,3 -propanediol , 1 , 4 -butanediol , 1 , 5-pentanediol , 1 , 6 -hexanediol , neopentyl glycol ,

1, 10 -decanediol , glycerol , trimethylolpropane , and a mixture thereof . The polyester polyol further includes those prepared from lactones . The polyester polyol prepared from lactones is preferably, but not limited to, e - caprolactone .

In addition to the above-mentioned polyether polyol and/or polyester polyol , the polyurethane rigid foam according to the present invention may also comprise , but not limited to, a polycarbonate polyol and a polymer polyol .

The polycarbonate polyol is preferably, but not limited to , a polycarbonate diol synthesized by the reaction of a diol with a dialkyl or diary1 carbonate or phosgene . The diol is preferably, but not limited to, 1 , 2 -propanediol , 1 , 3 -propanediol , 1 , 4 -butanediol , 1 , 5-pentanediol , 1 , 6 -hexanediol , diethylene glycol , s-Trioxane diol , and a mixture thereof . The dialkyl or diary1 carbonate is preferably, but not limited to, diphenyl carbonate .

The polymer polyol is a stable dispersion formed by solid enhanced particles in a polyol liquid. Any known polymer (or dispersion) polyol in the art can be included in the polyol component according to the present invention . It includes , but is not limited to, SAN polymer polyol , PHD polymer polyol and PIPA polymer polyols . The SAN polymer polyol is made by in-situ polymerization of a mixture of acrylonitrile and styrene in a base polyol ; the PHD polymer polyol is made by in-situ polymerization of a isocyanate mixture and a diamine in a base polyol ; the PUPA polymer polyol is made by in-situ polymerization of a isocyanate mixture and a diol and/or diol -amine in a base polyol .

The measurement of hydroxy1 number is known for the skilled as such and described , for example , in Houben Weyl , Methoden der Organischen Chemie , vol . XIV/2 Makromolekulare Stof fe , p. 17 , Georg Thieme Verlag ; Stuttgart 1963 , which is incorporated by reference herein in its entirety .

When used in the present invention , the functionality and hydroxy1 number of an organic polyol mean the average functionality and the average hydroxy1 number in each case , unless otherwise indicated .

The skilled in the art can add, if needed, a blowing agent , a chain extender, a catalyst , a surfactant , a f1ame retardant , a filler or other additives suitable for the preparation of the polyurethane rigid foam according to the present invention . The blowing agent according to the present invention may be a variety of physical blowing agents or chemical blowing agents . Examples of said blowing agent are , preferably but not limited to , water , halogenated hydrocarbons , hydrocarbons and gases . The halogenated hydrocarbons are preferably, but not limited to , monochlorodifluoromethane , dichloromonofluoromethane , dichlorofluoromethane , trichlorof luoromethane , or a mixture thereof . The hydrocarbons are preferably, but not limited to , butane , pentane , cyclopentane , hexane , cyclohexane , heptane , or a mixture thereof . The gases are preferably, but not limited to , air , CO2 or N2. The blowing agent is particularly preferably water The amount of the blowing agent is dependent on the desired density of the polyurethane . The chain extender used in the present invention is usual ly an active hydrogen atom-containing compound having a molecular weight of less than 800 , preferably a molecular weight of 18-400. The active hydrogen atom-containing compound is preferably, but not limited to , alkylene glycols , dialkylene glycols , polyalkylene polyol , or a mixture thereof, for example , ethylene glycol , 1 , 4 -butanediol , 1 , 6 -hexanediol , 1 , 7-heptanediol , 1, 8 -octanediol , 1 , 9 -nonanediol , 1 , 10 -decanediol , diethylene glycol , dipropylene glycol , polyoxyalkylene glycol, or a mixture thereof . The active hydrogen atom-containing compound may also include other grafted or unsaturated alkylene glycol or a mixture thereof , for example , 1 , 2 -propanediol ,

2 -methyl -1,3 -propanediol , 2 , 2 -dimethyl -1,3 -propanediol ,

2 -butyl -2 -ethyl -1 , 3 -propanediol , 2 -butene-1 , 4 -diol ,

2-butyne-l, 4-diol , alkanol amine , N-alkyl -dialkanol amine . The N-alkyl -dialkanol amine is preferably, but not limited to , ethanol amine, 2-propanol amine, 3 -amino-2 , 2 -dimethylpropanol , N-methyl -diethanol amine, N-ethyl -diethanol amine, or a mixture thereof . The active hydrogen atom-containing compound may further include aliphatic amines , aromatic amines , or a mixture thereof . The aliphatic amines and aromatic amines are preferably, but not limited to, 1 , 2 -ethylenediamine , 1 , 3 -propanediamine , 1 , 4 -butanediamine , hexamethylene diamine , isophorone diamine , 1 , 4 -cyclohexane diamine , Ν,Ν' -diethyl -phenylenediamine , 2 , 4 -diaminotoluene , 2 , 6 -diaminotoluene , or a mixture thereof . The catalyst according to the present invention is preferably, but not limited to, amine catalysts , organic metal catalysts , or a mixture thereof . Said amine catalysts are preferably, but not limited to, triethylamine , tributylamine , triethylenediamine , N-ethylmorpholine ,

N, N, ' , ' -tetramethyl -ethylene diamine , pentamethyl -diethylene triamine , N, N-methylaniline ,

N, N-dimethylaniline, or a mixture thereof . Said organic metal catalysts are preferably, but not limited to , organotin compounds , for example , tin ( II ) acetate , tin ( II ) octoate , tin ethylhexanoate , tin laurate , dibutyltin oxide , dibutyltin dichloride , dibutyltin diacetate , dibutyltin maleate , dioctyltin diacetate and a mixture thereof .

The surfactant used in the present invention is preferably, but not limited to , ethylene oxide derivatives of siloxanes . The f1ame retardant used in the present invention may be an organic or an inorganic f1ame retardant . The organic f1ame retardant is preferably, but not limited to, tris (2 -chloroethyl ) phosphate (TCEP) , tris (2 -chloropropyl ) phosphate (TCPP) , trischloropropyl phosphate (TDCPP) , dimethyl methylphosphonate (DMMP) , triphenyl phosphate , me1amine orthophosphate (MPP) or a mixture thereof . The inorganic flame retardant is preferably, but not limited to, hydrated aluminum hydroxide , hydrated magnesium hydroxide , monoammonium phosphate , diammonium phosphate , ammonium chloride , boric acid, hydrated zinc borate or a mixture thereof .

The filler used in the present invention can be a variety of inorganic fillers or organic fillers . The inorganic filler is preferably, but not limited to, silicate minerals , metal oxides , metal salts , inorganic pigments , natural and synthetic mineral fibers , nano-materials , or a mixture thereof . Non-limiting examples are calcium silicate , calcium carbonate , fumed silica , nano-zinc oxide , barite , zinc sulfide , glass particles and wollastonite . The organic filler is preferably, but not limited to , crystalline wax, polymer polyol , organic microparticles and cork . The inorganic fillers or organic fillers may be used singly or in combination . The filler may serve to enhance the strength of the polyurethane layer, f1ame retardancy and so on .

The present invention will be further described below in combination with examples . The specific examples and methods disclosed herein are illustrative and not restrictive . EXAMPLES

The starting materials and devices used in this application are described as follows :

TDI distillation residue : NCO content of about 34 wt . % , a viscosity of about 12000 cps ( 25 ^"' C ) , available from Bayer MaterialScience AG;

Desmodur 44V20L: PMDI , NCO content of 30.5-32.5 wt . % , available from Bayer MaterialScience AG;

Desmophen 4030 M : polyether polyol , a hydroxy1 number of 380 , available from Bayer MaterialScience AG;

Desmophen 4034B : polyether polyol , a hydroxy1 number of 440 , available from Bayer MaterialScience AG;

Arcol 1021 : polyether polyol, a hydroxy1 number of 56, available from Bayer MaterialScience AG;

L-6920 : a foam stabilizer available from Moment ive ;

Polycat 8 : a catalyst available from Air Products ;

Polycat 41 : a catalyst available from Air Products ;

HK 470 Type of conventional high-pressure foaming machine : available from Hennecke company .

The isocyanate- react ive components used in the amounts shown in Table 1 were mixed and then reacted in HK 470 Type of conventional high-pressure foaming machine based on the amounts shown in Table 2. After the reaction, the liquid polyurethane is poured into a mold of 20 cm * 30 cm * 60 cm, the temperature of the mold is controlled between 25-35 , the temperature of raw materials is 25-30 , the mixing pressure of the high-pressure machine is 120-150 bar . The foam rises substantially freely since there is no cover on the mold . After 20 minutes , it was demolded and kept at room temperature for 24 hours , and the top part which is uneven is cut off . The remaining lower part is cut into test samples with desired size in accordance with the foam test standards . A group of five samples were tested in terms of mechanical properties (according to GB/T 8813-2008) and heat insulation properties (according to GB/T3399-1982 ) . The test data are shown in Table 2.

The polyurethane rigid foams of Examples 2 and 3 have a lower thermal conductivity and therefore better insulation properties In addition, the polyurethane rigid foams of Examples 2 and 3 have a higher compression strength in the direction vertical to foaming when compared with that of Example 1 having the same density .

Table 1: Isocyanate- reactive components

Table 2 : Polyurethane rigid foam and the properties thereof

Examples unit 1* 2 3

isocyanate - reactive

pbw 100 100 100 component

Desmodur 44V20L pbw 100 80 75

TDI residue pbw 0 20 25

Cream time second 147 209 215 Tack - f ree time second 300 387 398

Foam density kg/m ³ 34.7 34.5 34.7 compression

strength

KPa 131 136 164 (vertical

direction)

Thermal

mW/m. K 22.27 21.67 21.64 conductivity

* comparative example