KR20100102410A - Preparation of polyisocyanates and a rigid polyurethane foam using toluene diisocyanate distillation residues - Google Patents

Abstract

PURPOSE: Manufacturing methods of polyisocyanate and a rigid polyurethane foam are provided to produce the polyisocyanate with the content of isocyanate of 25~35%, having the excellent viscosity. CONSTITUTION: A manufacturing method of polyisocyanate comprises the following steps: adding toluene as a solvent to a toluene diisocyanate distillation residue with the content of a toluene diisocyanate monomer of 40~50wt%, and stirring the mixture while heating to 100~110deg C; cooling the mixture to 50~80deg C, and partially removing the solvent from the mixture by vacuuming; adding crude diphenyl methane diisocyanate and stirring; and completely removing the solvent from the mixture.

Description

Preparation of Polyisocyanates and a Rigid Polyurethane Foam Using Toluene Diisocyanate Distillation Residues

The present invention relates to a method for producing a polyisocyanate and a rigid polyurethane foam using toluene diisocyanate distillation by-products, the content of the isocyanate is good, the viscosity is excellent, and is economical by using toluene diisocyanate by-products that have been incinerated and buried in the past It relates to an invention that can prevent toxic gases generated during disposal.

Toluene diisocyanate is generally prepared by hydrogenating dinitrotoluene to produce toluenediamine and then reacting with phosgene. By-products are inevitably generated in the process of distilling crude crude toluene diisocyanate, which contains useful toluene diisocyanate, as well as burette compounds, polycarbodiimide and iso Cyanurates, various isocyanate adducts and tarry materials and the like.

The general composition of toluene diisocyanate by-product is shown in Table 1 below.

Kinds Toluene diisocyanate High Boiling Material ^* Tar Content (% by weight) 20-50 0 to 20 50 to 80 * High boiling point materials: biuret compounds, polycarbodimids, isocyanurates, various isocyanate adducts

Toluene diisocyanate by-products are incinerated mainly for use as fuels, causing the problem of polluting the environment by generating toxic gases harmful to the human body. In addition, when incineration, the viscosity of the by-products is high and difficult to transfer, there is a problem that adds enormous costs, such as a transfer facility and toxic gas treatment device.

Therefore, many studies have been conducted because methods for applying toluene diisocyanate by-products such as inactivating active isocyanate and using it as an additive of various plastic materials or recovering toluene diisocyanate monomer are required.

U.S. Patent No. 4,032,574 introduces a process for preparing polyols by addition of methylene cellulsolve and caustic soda to toluene diisocyanate by-products, followed by addition polymerization of ethylene oxide and propylene oxide. However, since this method is a pressure reaction, there is a problem that the equipment investment is followed.

U.S. Patent No. 4,560,040 introduces a method of reacting toluene diisocyanate by-products with water to inactivate active isocyanate groups and then dispersing them in high molecular weight polyols and using them as additives in foams or elastomers. However, in this case, there is a problem that the economic value of the product falls.

US Pat. No. 6,673,960 discloses a method for recovering toluenediamine after the decomposition of toluene diisocyanate by-product using a supercritical fluid. However, in order to recover toluenediamine, a large amount of solids are generated in a process step, and a problem of corrosion due to the use of a supercritical fluid occurs, and an expensive facility other than the existing facility needs to be introduced.

Korean Patent Laid-Open Publication No. 1999-024063 discloses a method in which toluene diisocyanate by-product is dissolved in an isocyanate compound and an activated hydrogen substance in a suitable temperature range using a solvent, and then reacted to produce a modified body and applied to a rigid polyurethane foam. Doing. However, there is a problem that the product obtained by this method is poor in physical properties and contains a solvent, which may cause environmental pollution.

In general, polyurethane is a high molecular compound having a urethane bond obtained by chemical reaction between a compound containing an isocyanate group (-NCO) and a compound having active hydrogen, as shown in the following Scheme 1. They are widely used and attracted a great deal of attention in all industries, such as cushioning materials for automobiles and furniture, insulation materials for buildings, adhesives, waterproofing materials, flooring materials, artificial leather, coating materials, sealing materials and artificial fibers, depending on the raw materials and applied technologies.

In Scheme 1, A and B are aromatic or aliphatic compounds.

The isocyanate compound used as a raw material in the production of such polyurethane is diphenylmethanediisocyanate (C ₁₅ H ₁₀ N ₂ O ₂ , MDI), hexamethylene diisocyanate (Hexamethylenediisocyanate: OCN (CH ₂ ) ₆ NCO ) And toluenediisocyanate (C ₉ H ₆ N ₂ O ₂ , TDI), preferably diphenylmethane diisocyanate and toluene diisocyanate are mainly used for producing rigid polyurethane foams. Of these, diphenylmethane diisocyanate mainly uses crude diphenylmethane diisocyanate, which is generally a product having an isocyanate content of about 31% and a viscosity of 200 cps (25 ° C.), for toluene diisocyanate, The isocyanate content is about 48% and the viscosity is 3 cps (25 ° C.).

As the compound having active hydrogen, a polyol is mainly used, and preferably, a polyester polyol and a polyether polyol are most commonly used.

The polyester polyol is obtained by condensation reaction of polybasic acid and polyhydric alcohol, and polyether polyol is obtained by addition polymerization of ethylene oxide or propylene oxide.

Therefore, there is an urgent need for a method for treating such toluene diisocyanate by-products to increase the added value and to use industrially.

Accordingly, the present inventors have made an effort to solve the above problems, the content of the isocyanate is 25 to 35% by using toluene diisocyanate by-product, the purpose is to produce a polyisocyanate excellent in viscosity.

In addition, the object is to produce a rigid polyurethane foam by catalytic reaction of the polyisocyanate.

The present invention relates to a first step of dissolving a mixture by adding toluene as a solvent to toluene diisocyanate by-product having a content of toluene diisocyanate monomer of 40 to 60% by weight and stirring the mixture to 100 to 110 ° C .; Cooling the dissolved mixture to 50-80 ° C. and then applying a vacuum to remove a part of the solvent, followed by adding crude diphenylmethane diisocyanate and stirring the second mixture; and vacuuming the stirred mixture under a nitrogen atmosphere. A third step of completely removing the solvent; Polyisocyanate production method characterized in that it comprises a.

Polyisocyanate prepared by the production method of the present invention has an isocyanate content of 25 to 35%, excellent viscosity, and could be used to prepare a rigid polyurethane foam.

In addition, it was possible to regenerate wastes discarded through incineration as raw materials to increase value added, and to prevent air pollution by toxic gases generated during incineration.

Hereinafter, the present invention will be described.

The present invention is characterized by a method for producing polyisocyanate by reacting toluene diisocyanate by-product with diphenylmethane diisocyanate and a rigid polyurethane foam based on the produced polyisocyanate.

Toluene Diisocyanate By-Product

Typical toluene diisocyanate by-products contain about 20-50% by weight of toluene diisocyanate as described above.

In order to utilize toluene diisocyanate by-products as a useful component, it is important to maintain the content of each component at a certain level. In general, the content of toluene diisocyanate monomers is distillation process, while the content of high boiling point and tarry substances is not large. As the conditions vary greatly, the addition of additional toluene diisocyanate monomers can be used to match the proportions of each content. The toluene diisocyanate by-product of the present invention preferably contains 40 to 60% by weight of toluene diisocyanate monomer with respect to the total toluene diisocyanate by-product. When the content of toluene diisocyanate monomer exceeds 60% by weight, the expensive toluene diisocyanate monomer is added. The problem of cost increase may occur, and if the composition is less than 40% by weight, the composition of the toluene diisocyanate monomer and other components in the byproduct may occur, so that the above range is preferable. The composition of toluene diisocyanate by-products used in the present invention is shown in Table 2 below.

Kinds Toluene diisocyanate High Boiling Material ^* Tar Content (% by weight) 40 to 60 0 to 10 30 to 70 * High boiling point materials: biuret compounds, polycarbodimids, isocyanurates, various isocyanate adducts

However, the composition of the toluene diisocyanate by-product of the present invention is not limited by the above Table 2.

Polyisocyanate manufacturing method

A first step of dissolving the mixture by adding toluene to toluene diisocyanate by-product having a content of toluene diisocyanate monomer of 40 to 60% by weight and heating to 100 to 110 ° C. while stirring;

A second step of cooling the dissolved mixture to 50-80 ° C., followed by vacuum to remove a part of the solvent, and then adding crude diphenylmethane diisocyanate and stirring; and

A third step of vacuuming the stirred mixture under a nitrogen atmosphere to completely remove the solvent;

It includes and describes the manufacturing method in more detail as follows.

The toluene of the first step is preferably added to 100 to 500 parts by weight based on the total toluene diisocyanate by-products, if the content of toluene is less than 100 parts by weight of the by-products there are too many precipitates in the production of polyisocyanate stability This may fall, and the above range is preferable because a problem that the workability is deteriorated and the manufacturing cost may be exceeded if it exceeds 500 parts by weight.

The crude diphenylmethane diisocyanate of the second stage is preferably an isocyanate content of 30 to 32% by weight and a viscosity of 300 cps or less. If the viscosity is 300 cps or more, the viscosity of the polyisocyanate may be too high, leading to poor processability. 300 cps or less is preferable because it can. The weight ratio of toluene diisocyanate by-product and crude diphenylmethane diisocyanate is preferably 1: 0.5 to 2.0. If the weight ratio is 1: 0.5 or less, the viscosity of the resulting polyisocyanate may be too high, and 1: 2.0 The above weight ratio is preferable because the above problem may cause a cost increase.

The third step is to vacuum the composition stirred in the second step under a nitrogen atmosphere to completely remove the solvent toluene to prepare a polyisocyanate.

The polyisocyanate prepared as described above has an isocyanate content of 25 to 35% and a physical property having a viscosity of 700 cps or less. If the isocyanate content of the polyisocyanate is 25% or less, the viscosity may be too high to be difficult to use, and if it is 35% or more, the reactivity may be too high and the cost of the product may increase. In addition, when the viscosity is 700 cps or more may be difficult to foam when applying the polyurethane foam in the present invention was prepared a polyisocyanate having a physical property of the above range.

Rigid polyurethane foam

Polyurethane is a high molecular compound having a urethane bond obtained by chemical reaction between a substance containing an isocyanate group and a compound containing active hydrogen. Here, as the material containing isocyanate, the polyisocyanate prepared in the present invention can be used, and as the compound containing active hydrogen, ordinary polyol can be used.

Polyols usable in the present invention include polyoxyalkylene polyols which are ring-opening polymerization products of ethylene oxide or propylene oxide, and polyester polyols which are condensation reaction products of polycarboxylic acids and polyhydroxy alcohols, and these may be used alone or in combination.

Conventional catalysts may be used to prepare rigid polyurethane foams. The catalysts usable in the present invention include triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, monoethanolamine, diethanolamine, dimethylethanolamine, triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, di Ethylenetriamine, N, N, N ', N'-tetramethylbutanediamine, N, N, N', N'-tetramethyl-1,3-butanediamine, N, N, N ', N'-tetra Ethylhexamethylenediamine, bis [2- (N, N-dimethylamino) ethyl] ether, N, N-dimethylbenzylamine, N, N-dimethylcyclohexylamine, N, N, N ', N ", N" Pentamethyldiethylenetriamine, triethylenediamine, formic acid and other salts of triethylenediamine, amino groups and oxyalkylene adducts of the first and second amines, N, N-dialkyl Aza ring compounds, a number of the N, N ', N ", such as Pera jinryu-to trialkyl-amino-alkyl-hexahydro-triazol jinryu of β- aminocarbonyl, such as amine-based urethanization catalysts may be used.

In addition, water (H ₂ O) may be added to react with the isocyanate to release the carbon dioxide gas to act as a blowing agent.

In addition, in the preparation of polyurethane, as a secondary foaming agent, fluorocarbon-based and cyclopentane-based compounds may be added, and conventional foam stabilizers, flame retardants, and other additives may be used together.

The method for preparing polyisocyanate and hard polyurethane foam from the toluene diisocyanate by-product of the present invention is a distillation column for recovering the effective substance compared to the method for recovering toluene diisocyanate monomer by distillation or toluene diamine using a supercritical fluid. It is desirable because it does not require equipment investment and operation costs such as refining equipment, and it can recycle valuable resources that were discarded without causing toxic gas generation and environmental problems caused by incineration of by-products.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Preparation of Polyisocyanate

Example 1

Into a three-neck 500 mL round flask equipped with a stirrer and a thermometer, 84 g of toluene diisocyanate by-product and 44% of toluene diisocyanate by-product and 44% by weight of toluene diisocyanate monomer were added as shown in Table 3 and stirred while flowing nitrogen at a temperature of 100 to 110 ° C. It was. After stirring for about 1 hour, the temperature was cooled to 50 ~ 70 ℃ and reduced to 50 mmHg or less to remove 270 g of toluene.

126 g of M-5S (BASF) was added to the flask so that the weight ratio of toluene diisocyanate by-product to crude diphenylmethane diisocyanate was 0.67, and the mixture was stirred for 1 hour while maintaining the temperature at 50 to 70 ° C, and then 50 mmHg After the pressure was reduced below, toluene was completely removed to prepare a brown polyisocyanate having no precipitate and stable viscosity.

Examples 2 to 6 and Comparative Examples 1 to 3

Polyisocyanate was prepared in the same manner as in Example 1.

division Example Comparative example One 2 3 4 5 6 One 2 3 Among TDI By-Products
Monomer Content (%) 44 60 52.8 60 37 50 70 37 37 TDI by-product (g) 84 100 100 144 110 100 100 144 144 MDI Type M-5S M-5S M-5S M-20 M-5S M-5S M-5S M-20 M-5S MDI (g) 126 150 41.7 96 165 150 150 96 96 TDI By Product /
MDI Weight Ratio 0.67 0.67 1.40 1.50 0.67 0.67 0.67 1.50 1.50 Toluene (g) 336 400 400 576 440 400 400 576 576 Total (g) 546 650 541.7 816 782 650 650 816 816

[Property Measurement Evaluation]

Isocyanate content, hydrolyzable chlorine and viscosity of the polyisocyanate prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were measured by the following method, and the results are shown in Table 4 below.

1. Isocyanate Content

The content of isocyanate was calculated using potentiometric titration after reacting polyisocyanate with excess 1 N di-n-butylamine.

2. Hydrolyzable Chlorine

The hydrolyzable chlorine was used by slightly modifying the ASTM D 1638 method. The reaction was carried out by adding methanol to the polyisocyanate, followed by melting the sample with acetone, followed by the addition of water, heating, and cooling. The method of performing potentiometric titration with the (AgNO ₃ ) solution was used.

3. Viscosity

Viscosity was measured at 25 ° C. using a Brookfield viscometer.

division Example Comparative example One 2 3 4 5 6 One 2 3 Isocyanate Content (%) 32.5 32 31.6 32.6 30.32 30.12 32.5 27.9 27.40 Hydrolyzable Chlorine (ppm) 720 857 725 793 718 725 1361 1010 1160 Viscosity
(25 ℃, cps) 680 150 580 350 680 480 52 69000 9000

Rigid Polyurethane Foam Manufacturing

Examples 7-9

The polyisocyanate prepared in Examples 1, 4, and 6 was used at 6,000 rpm for 5 seconds at room temperature using a resin premix and a high speed mixer composed of polyether polyol, foaming agent, flame retardant, catalyst and blowing agent, and other additives as shown in Table 5 below. The rigid polyurethane foams were prepared by stirring followed by reaction free foaming with an isocyanate index.

Comparative Example 4

Manufactured in the same manner as in Examples 7 to 9, but generally used polyether polyols RP-6455 (BASF), TE-360 (BASF) and the crude diphenylmethane diisocyanate reacted with an isocyanate index 110 hard polyurethane Foams were prepared.

division
(Parts by weight) Example Comparative example 7 8 9 4 Polyisocyanate Example 1 Example 4 Example 6 MDI ¹⁾ Polyether
Polyol RP-6455 50 50 50 50 TE-360 50 50 50 50 Foam stabilizer B-8462 ²⁾ 2.5 - 2.5 2.5 Flame retardant TCPP 20 20 20 20 blowing agent H ₂ 0 1.5 1.5 1.5 1.5

Other additives DC-193 ³⁾ - 2.5 - - PC-8 ⁴⁾ 1.5 1.5 1.5 1.5 T-45 ⁵⁾ 1.0 1.0 1.0 1.0 HCFC-146 25 25 25 25 Isocyanate Index 110 110 110 110 1) MDI: Diphenylmethane diisocyanate (M-20, BSAF)
2) B-8462: Goldschmit, Tegostab
3) DC-193: Air Products, DABCO
4) PC-8: Air Products, DABCO
5) T-45: Air Products, DABCO

[Measurement Evaluation 2]

The reactivity of the rigid polyurethane foams prepared in Examples 7 to 9 and Comparative Example 4 was confirmed by C / T, G / T and TF / T, and other physical properties of the appearance, such as density, compressive strength and independent bubble ratio Is shown in Table 6 below.

C / T (cream time) is the time when the liquid shows a cream state after mixing resin premix composed of polyol and MDI, G / T (gel time) is the time when gelation occurs as the mixture progresses and TF / T ( tack free time) was measured by dividing the time from the surface of the foam to the non-sticky.

division Example Comparative example 7 8 9 4 Responsive C / T (sec) 23 22 23 27 G / T (sec) 110 96 110 97 TF / T (sec) 180 145 180 140 Density (kg / m ³ ) 38.4 37.5 39.6 40.3 Compressive strength (kgf / cm ² ) 2.1 2.3 2.1 2.5 Independent Bubble Rate (%) 85 89 87 90 Exterior mum mum mum Pale yellow

As shown in Table 6 above, crude diphenylmethane diisocyanate (M-20, BASF), which generally uses Examples 1 and 2, which are polyisocyanates synthesized from toluene diisocyanate by-products, is used. Alternative Application Example 16 and Example 17 show experimental data, reactivity, physical properties, and properties of the rigid polyurethane foam of Comparative Example 8 using crude diphenylmethanediisoyanate (M-20, BASF). The experimental results on the appearance showed good results with little difference.

Therefore, the use of polyisocyanates prepared using the toluene diisocyanate by-products prepared in the present invention for the production of rigid polyurethane foams replaces the existing expensive crude diphenylmethane diisoyanate and polyether polyols. It is expected to be possible.

1 is a result of FTIR analysis of the polyisocyanate prepared according to Example 5.

Claims (6)

A first step of dissolving the mixture by adding toluene as a solvent to toluene diisocyanate by-product having a content of toluene diisocyanate monomer of 40 to 60% by weight and stirring the mixture to 100 to 110 ° C .; A second step of cooling the dissolved mixture to 50-80 ° C., followed by vacuum to remove some of the solvent, and then adding crude diphenylmethane diisocyanate and stirring; and A third step of vacuuming the stirred mixture under a nitrogen atmosphere to completely remove the solvent; Polyisocyanate production method comprising a. The method of claim 1, The toluene is a method for producing a polyisocyanate, characterized in that 100 to 500 parts by weight based on the total toluene diisocyanate by-product. The method of claim 1, The weight ratio of the toluene diisocyanate by-product and the crude diphenylmethane diisocyanate is 1: 0.5 to 2.0 method of producing a polyisocyanate. The method of claim 1, The polyisocyanate has a content of 25 to 35% of isocyanate, and has a viscosity of 700 cps (25 ° C.) or less. The rigid polyurethane foam which uses the polyisocyanate manufactured in Claim 1 or 4 as a raw material. The method of claim 5, Triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, monoethanolamine, diethanol Amine, dimethylethanolamine, triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, diethylenetriamine, N, N, N ', N'-tetramethylbutanediamine, N, N, N' , N'-tetramethyl-1,3-butanediamine, N, N, N ', N'-tetraethylhexamethylenediamine, bis [2- (N, N-dimethylamino) ethyl] ether, N, N- Dimethylbenzylamine, N, N-dimethylcyclohexylamine, N, N, N ', N ", N" -pentamethyldiethylenetriamine, triethylenediamine, formic acid and other salts of triethylenediamine, first and second Amino groups of two amines, oxyalkylene adducts, azacyclic compounds such as N, N-dialkylpiperazines, and β-amino of various N, N ', N "-trialkylaminoalkylhexahydrotriazines Ka Rigid polyurethane foam which comprises using at least one amine-based urethane catalyst selected from the group consisting of carbonyl.

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