WO1993019109A1 - Absorbent for isocyanate vapours - Google Patents

Absorbent for isocyanate vapours Download PDF

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Publication number
WO1993019109A1
WO1993019109A1 PCT/AU1993/000110 AU9300110W WO9319109A1 WO 1993019109 A1 WO1993019109 A1 WO 1993019109A1 AU 9300110 W AU9300110 W AU 9300110W WO 9319109 A1 WO9319109 A1 WO 9319109A1
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WO
WIPO (PCT)
Prior art keywords
foam
absorbent
isocyanate
polyurethane foam
absorbent according
Prior art date
Application number
PCT/AU1993/000110
Other languages
French (fr)
Inventor
Allen Wood
Ronald S. Park
David M. Gilliver
Michael D. Joubert
Original Assignee
Pacific Dunlop Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pacific Dunlop Limited filed Critical Pacific Dunlop Limited
Publication of WO1993019109A1 publication Critical patent/WO1993019109A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28042—Shaped bodies; Monolithic structures
    • B01J20/28045—Honeycomb or cellular structures; Solid foams or sponges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28011—Other properties, e.g. density, crush strength
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4833—Polyethers containing oxyethylene units
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2110/00—Foam properties
    • C08G2110/0008—Foam properties flexible
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2110/00—Foam properties
    • C08G2110/0041—Foam properties having specified density
    • C08G2110/005—< 50kg/m3

Definitions

  • ABSORBENT FOR ISOCYANATE VAPOURS The present invention relates to absorbents for isocyanate vapours.
  • Isocyanates react with compounds containing active hydrogen atoms.
  • a polyisocyanate will react with a polyol to form, a polyurethane.
  • Isocyantes also react with amines, carboxylic acids and water.
  • the polyisocyanatesmost generally used in the production of polyurethanes are toluene diisocyanate (TDI), and diphenyl methane diissocynate (MDI) .
  • TDI is an extremely noxious substance, having a TLV of 5 p.p.b.. Consequently the escape of TDI vapours into the environment even at low levels is most undesirable.
  • TDI vapours emitted with other off-gases during the production of polyurethane foam have traditionally been removed by aqueous scrubbers.
  • the TDI reacts with water to form a harmless insoluble polyurea.
  • TDI is immiscible with water. Consequently, the reaction between TDI and water in the liquid phase occurs only at the interface between the droplets of TDI and water in the scrubber. As a result the rate of reaction is relatively slow and furthermore the efficiency of the scrubber decreases with the time possibly as a result of insoluble polyurea restricting the area of the interface between droplets of TDI and water.
  • Solid adsorbents for TDI vapour have been proposed.
  • activated carbon is a very effective adsorbent.
  • the use of activated carbon to remove TDI vapours is very expensive.
  • An object of the present invention is to provide polymeric foams having improved absorption characteristics. Accordingly the present invention provides an absorbent for isocyanate vapours, the absorbent comprising an absorbent for isocyanate vapours, the absorbent comprising a porous compression resistant polyurethane foam formed from an isocyanate and a polyether polyol.
  • the physical nature of the foam is also very important in determining its suitability as an isocyanate scrubber medium.
  • the foam density can be high (50 - 100 kg/m 3 ) or low (10 - 20 kg/m 3 ) .
  • the best isocyanate vapour removal efficiency per unit wt. of foam used is achieved by using a low density foam, preferably one of 10 - 15 kg/m 3 .
  • the foam porosity airflow is preferably high so as to offer the least resistance to the flow of gases through the scrubber, and to allow the use of a thickness of foam which will have a practically useful lifetime before breakthrough occurs.
  • the porosity airflow as measured by AS.2282.14 should be greater than 1.7 L/S, and more preferably greater than 2.7 L/S.
  • the foam should not be too soft, otherwise, due to the relatively high gas flow and the pressure drop across the foam, it can become compressed and thereby severely restrict the passage of gases. It should therefore be hard enough to resist the compressive forces of the pressure drop and should exhibit an indentation force deflection value at 40% compression (IF 40 as measured by AS.2282.8) of at least 40 Newtons and more preferably 80 Newtons depending on the particular airflow/pressure drop conditions in the scrubber.
  • the preferred foam should have a cell count of more than 40 cells/25mm and preferably more than 60 cells/25 mm as determined by method AS.2282.5.
  • the polyurethane foam is produced using low levels of catalysts such as stannous octoate.
  • the present invention also provides apparatus for extracting isocyanate vapour from off-gases formed during the production of polyurethane.
  • the apparatus comprises means for extracting off-gases produced during the production of polyurethane foam, containing means for containing the absorbent of the invention and extraction means for causing the off-gases to flow through absorbent contained in the containing means.
  • Figure 1 is a schematic representation of apparatus according to the invention. It illustrates a typical layout of a plant that uses TDI as one of the reactants to produce polyurethane foam.
  • Reactants used to produce the polyurethane foam are mixed and deposited onto a continuous paper mould formed in the foam tunnel. These reactants combine resulting in the production of a continuous block of foam.
  • the mould paper is then removed from the solid foam block and as the continuous block passes through the block cutter enclosure, it is cut into discrete blocks for further handling in the curing area.
  • vents 5, 6 and 7 for extracting off-gases from the foam tunnel 2, paper take-off enclosure 3 and the block cutter enclosure 4 respectively.
  • the off-gases are then passed through conduit 8 to absorption column 9 packed with modified polyurethane foam.
  • the off-gases are caused to flow through the absorption column by an extraction fan 10. Off-gases from the absorption column are then passed to atmosphere through stack 11.
  • Table 1 illustrates the performance of a number of polyurethane foams in plant trials using the apparatus illustrated in Figure 1.
  • Off-gases from a polyurethane foam producing plant normally contain additional carbon dioxide, auxiliary blowing agents such as CFC 11 and methylene chloride, water vapour and amine catalyst residues.
  • samples of polyurethane foam measuring 150 mm x 150 mm x 25 mm were attached to a supporting medium within the column 9. The samples were weighed before and after being exposed to the off-gases for 10 hours. As well as exhibiting a weight increase, the foams were also much harder after being exposed to the extracted gases.
  • the time required for TDI vapour to break through test samples of polyurethane foam under various conditions was determined using laboratory equipment. Air was bubbled through TDI at the rate of 10 litres/minute to produce a TDI vapour concentration in the air of 180 ppb. The TDI laden air was then passed through an absorportion column packed with the polyurethane foam under test and the concentration of TDI in the air exiting the absorportion column measured with an autostep monitor. The time taken for the polyurethane foam to cease effectively absorbing TDI in the air passed through it was determined by measuring the time from commencement to the time when the TDI concentration in the air exiting the absorportion column reached 20 ppb. The effect on breakthrough time of moisture and amine type catalyst residues was determined by incorporating moisture and amine vapour respectively into the TDI laden air. The results of the tests are recorded in Table 4. Then show that neither moisture nor amine type catalyst had an effect on breakthrough time.
  • Explosion reticulated polyurethane foams derived from polyester polyols are normally used in filter applications.
  • Table 1 demonstrates that polyether polyol derived foams are much better absorbents of TDI vapour from off-gases than polyester polyol derived foams.
  • Table 2 provides the formulations used in producing the polyether polyol derived foams referred to in Table 1.
  • Table 3 summarizes the Australian and corresponding International standards used to determine the physical properties of the foams referred to in Table 1. TABLE 3
  • Foams 1 - 9 are polyether - refer to attached Formulation Table No.2
  • Foam 10 is polyether and is explosion reticulated.
  • Foams 11 and 12 are polyester - Foam 11 is explosion reticulated.
  • Foam 12 is alkali reticulated.
  • Polyol 1 is Voranol 3142 supplied by Dow Chemical (Australia) Ltd.
  • Polyol 3 is Voranol 4701
  • Polyol 2 is Daltocel 34 Al supplied by ICI Australia Ltd.
  • Dabco 33LV is an amine catalyst supplied by Air Products & Chemicals Inc. U.S.A. Niax Al " " Union Carbide Corporation U.S.
  • Silicone BF2370 is a silicone stabiliser supplied by TH Goldschmidt AG - Germany
  • CFC 11 is Trichlorofluoromethane

Abstract

The specification describes polyurethane foams for absorbing isocyanate vapours formed during the manufacture of polyurethane foam. The polyurethane foams are produced from an isocyanate and a polyether polyol and are porous and compression resistant. An apparatus for removing isocyanate vapours from off-gases produced during the manufacture of polyurethane foam is also disclosed. The apparatus includes a container packed with a polyether polyol derived polyurethane foam through which off-gases produced during the production of polyurethane foam are passed.

Description

ABSORBENT FOR ISOCYANATE VAPOURS The present invention relates to absorbents for isocyanate vapours.
Isocyanates react with compounds containing active hydrogen atoms. Thus a polyisocyanate will react with a polyol to form, a polyurethane. Isocyantes also react with amines, carboxylic acids and water. The polyisocyanatesmost generally used in the production of polyurethanes are toluene diisocyanate (TDI), and diphenyl methane diissocynate (MDI) . TDI is an extremely noxious substance, having a TLV of 5 p.p.b.. Consequently the escape of TDI vapours into the environment even at low levels is most undesirable.
During the production of polyurethanes isocyanate vapours are emitted from the various production stages. TDI vapours emitted with other off-gases during the production of polyurethane foam have traditionally been removed by aqueous scrubbers. The TDI reacts with water to form a harmless insoluble polyurea. However TDI is immiscible with water. Consequently, the reaction between TDI and water in the liquid phase occurs only at the interface between the droplets of TDI and water in the scrubber. As a result the rate of reaction is relatively slow and furthermore the efficiency of the scrubber decreases with the time possibly as a result of insoluble polyurea restricting the area of the interface between droplets of TDI and water.
Solid adsorbents for TDI vapour have been proposed. For example activated carbon is a very effective adsorbent. However the use of activated carbon to remove TDI vapours is very expensive.
An object of the present invention is to provide polymeric foams having improved absorption characteristics. Accordingly the present invention provides an absorbent for isocyanate vapours, the absorbent comprising an absorbent for isocyanate vapours, the absorbent comprising a porous compression resistant polyurethane foam formed from an isocyanate and a polyether polyol.
Particularly useful are flexible polyurethane foams produced using polyols containing high levels of ethylene oxide derivatives, and polyols which have been ethylene oxide capped. Examples of such polyols are
Daltocel 34A1 supplied by I.C.I. Australia Ltd. and Voranol 4701 supplied by Dow Chemical Australia Ltd.
The chemical nature of the foam has a significant effect on the ability of the foam to absorb isocyanate vapour and this can be demonstrated by reference to Table 1 which indicates that polyether foam is much superior to polyester in this respect.
We have also found that foams produced using a stoichiometric deficiency of isocyanate (low isocyanate index but not necessarily a low isocyanate formulation level) exhibit improved isocyanate absorption properties. This is illustrated in Table 1.
The physical nature of the foam is also very important in determining its suitability as an isocyanate scrubber medium. The foam density can be high (50 - 100 kg/m3) or low (10 - 20 kg/m3) . However the best isocyanate vapour removal efficiency per unit wt. of foam used is achieved by using a low density foam, preferably one of 10 - 15 kg/m3. The foam porosity airflow is preferably high so as to offer the least resistance to the flow of gases through the scrubber, and to allow the use of a thickness of foam which will have a practically useful lifetime before breakthrough occurs. The porosity airflow as measured by AS.2282.14 should be greater than 1.7 L/S, and more preferably greater than 2.7 L/S.
The foam should not be too soft, otherwise, due to the relatively high gas flow and the pressure drop across the foam, it can become compressed and thereby severely restrict the passage of gases. It should therefore be hard enough to resist the compressive forces of the pressure drop and should exhibit an indentation force deflection value at 40% compression (IF40 as measured by AS.2282.8) of at least 40 Newtons and more preferably 80 Newtons depending on the particular airflow/pressure drop conditions in the scrubber.
In order to expose the maximum surface area of polymer to the vapours, the preferred foam should have a cell count of more than 40 cells/25mm and preferably more than 60 cells/25 mm as determined by method AS.2282.5.
Preferably the polyurethane foam is produced using low levels of catalysts such as stannous octoate.
The present invention also provides apparatus for extracting isocyanate vapour from off-gases formed during the production of polyurethane. The apparatus comprises means for extracting off-gases produced during the production of polyurethane foam, containing means for containing the absorbent of the invention and extraction means for causing the off-gases to flow through absorbent contained in the containing means.
An embodiment of the apparatus of the invention will now be described with reference to Figure 1. Figure 1 is a schematic representation of apparatus according to the invention. It illustrates a typical layout of a plant that uses TDI as one of the reactants to produce polyurethane foam.
Reactants used to produce the polyurethane foam are mixed and deposited onto a continuous paper mould formed in the foam tunnel. These reactants combine resulting in the production of a continuous block of foam. The mould paper is then removed from the solid foam block and as the continuous block passes through the block cutter enclosure, it is cut into discrete blocks for further handling in the curing area.
The embodiment disclosed in the diagram illustrates vents 5, 6 and 7 for extracting off-gases from the foam tunnel 2, paper take-off enclosure 3 and the block cutter enclosure 4 respectively. The off-gases are then passed through conduit 8 to absorption column 9 packed with modified polyurethane foam. The off-gases are caused to flow through the absorption column by an extraction fan 10. Off-gases from the absorption column are then passed to atmosphere through stack 11.
Table 1 illustrates the performance of a number of polyurethane foams in plant trials using the apparatus illustrated in Figure 1. Off-gases from a polyurethane foam producing plant normally contain additional carbon dioxide, auxiliary blowing agents such as CFC 11 and methylene chloride, water vapour and amine catalyst residues. During the plant trials, samples of polyurethane foam measuring 150 mm x 150 mm x 25 mm were attached to a supporting medium within the column 9. The samples were weighed before and after being exposed to the off-gases for 10 hours. As well as exhibiting a weight increase, the foams were also much harder after being exposed to the extracted gases.
The time required for TDI vapour to break through test samples of polyurethane foam under various conditions was determined using laboratory equipment. Air was bubbled through TDI at the rate of 10 litres/minute to produce a TDI vapour concentration in the air of 180 ppb. The TDI laden air was then passed through an absorportion column packed with the polyurethane foam under test and the concentration of TDI in the air exiting the absorportion column measured with an autostep monitor. The time taken for the polyurethane foam to cease effectively absorbing TDI in the air passed through it was determined by measuring the time from commencement to the time when the TDI concentration in the air exiting the absorportion column reached 20 ppb. The effect on breakthrough time of moisture and amine type catalyst residues was determined by incorporating moisture and amine vapour respectively into the TDI laden air. The results of the tests are recorded in Table 4. Then show that neither moisture nor amine type catalyst had an effect on breakthrough time.
During the plant trials it was also noted that moisture in the off-gases had no appreciable effect on the ability of a given foam to absorb TDI vapour.
Explosion reticulated polyurethane foams derived from polyester polyols are normally used in filter applications. However, Table 1 demonstrates that polyether polyol derived foams are much better absorbents of TDI vapour from off-gases than polyester polyol derived foams.
Table 2 provides the formulations used in producing the polyether polyol derived foams referred to in Table 1. Table 3 summarizes the Australian and corresponding International standards used to determine the physical properties of the foams referred to in Table 1. TABLE 3
TDI VAPOUR ABSORBING FOAM
Tests employed to determine properties
Australian Standard Equivalent
International or British Standard
Test Method
Foam Property Test Method
Foam Density AS.2282.3 ISO 1855
Foam Porosity BS 4443 Part Airflow AS.2282.14 6/Method 16 Foam Cell Count AS.2282.5 BS 4443/1/4
Foam IFD (IF40) (Hardness) AS.2282.8 ISO 2439
TABLE 4
LABORATORY SCALE TRIALS
BREAKTHROUGH TIME IN MINUTES
SAMPLE NO. * DRY AIR MOIST AIR MOIST AIR + AMINE
1 65 65 65 5 105 120 120
6 55 55 55
* Refer to Tables 1 and 2 for sample description.
TABLE 1
Weight pickup by flexible polyurethane foams after exposure to TDI containing vapours for 10 hours
Figure imgf000010_0001
Foams 1 - 9 are polyether - refer to attached Formulation Table No.2 Foam 10 is polyether and is explosion reticulated. Foams 11 and 12 are polyester - Foam 11 is explosion reticulated.
- Foam 12 is alkali reticulated.
TABLE 2 - FOAM FORMULATIONS
Figure imgf000011_0001
Polyol 1 is Voranol 3142 supplied by Dow Chemical (Australia) Ltd. Polyol 3 is Voranol 4701 Polyol 2 is Daltocel 34 Al supplied by ICI Australia Ltd. Dabco 33LV is an amine catalyst supplied by Air Products & Chemicals Inc. U.S.A. Niax Al " " Union Carbide Corporation U.S.
Silicone BF2370 is a silicone stabiliser supplied by TH Goldschmidt AG - Germany CFC 11 is Trichlorofluoromethane

Claims

Claims
1. An absorbent for isocyanate vapours, the absorbent comprising a porous compression resistant polyurethane foam formed from an isocyanate and a polyether polyol.
2. An absorbent according to Claim 1 wherein the polyether polyol contains a substantial proportion of ethylene oxide derivatives or has been capped with ethylene oxide.
3. An absorbent according to Claim 1 or Claim 2 wherein the polyurethane foam has a porosity air flow of greater than
1.7 litres/second as measured by AS2282.14.
4. An absorbent according to Claim 3 wherein the polyurethane foam has a porosity air flow greater than 2.7 litres/second.
5. An absorbent according to any one of the preceding claims wherein the polymeric foam has an indentation force deflection value of at least 40 Newtons as measured by AS2282.8.
6. An absorbent according to Claim 5 wherein the polymeric foam has an indentation force deflection value of at least
80 Newtons.
7. An absorbent according to any one of the preceding claims wherein the polymeric foam has a cell count of more than 40 cells/25 mm as determined by the method of AS2282.5.
8. An absorbent according to Claim 7 wherein the cell count is more than 60 cells/25 mm.
9. An absorbent according to Claim 1 wherein the polyurethane foam is formed in the presence of low levels of polymerisation catalyst of the type typified by stannous octoate.
10. Apparatus for extracting isocyanate vapours from off-gases formed during the production of polyurethane, the apparatus comprising means for extracting off-gases produced during the production of polyurethane foam, containing means for containing the absorbent according to any one of the preceding claims, and extraction means for causing the off-gases to flow through absorbent contained in the containing means.
PCT/AU1993/000110 1992-03-18 1993-03-18 Absorbent for isocyanate vapours WO1993019109A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPL1404 1992-03-18
AUPL140492 1992-03-18

Publications (1)

Publication Number Publication Date
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB991545A (en) * 1960-04-27 1965-05-12 Gen Tire & Rubber Co Improvements in or relating to the manufacture of polyetherurethanes
US3546146A (en) * 1965-07-12 1970-12-08 Troy Chemical Corp Films of improved uniformity and processes and compositions therefor
GB1301218A (en) * 1970-04-15 1972-12-29
JPS60192722A (en) * 1984-03-14 1985-10-01 Kurabo Ind Ltd Semi-rigid polyurethane foam
SU1637846A1 (en) * 1988-09-26 1991-03-30 Научно-производственное объединение "Полимерсинтез" Method of cleaning air from toluylene diisocyanate vapors

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB991545A (en) * 1960-04-27 1965-05-12 Gen Tire & Rubber Co Improvements in or relating to the manufacture of polyetherurethanes
US3546146A (en) * 1965-07-12 1970-12-08 Troy Chemical Corp Films of improved uniformity and processes and compositions therefor
GB1301218A (en) * 1970-04-15 1972-12-29
JPS60192722A (en) * 1984-03-14 1985-10-01 Kurabo Ind Ltd Semi-rigid polyurethane foam
SU1637846A1 (en) * 1988-09-26 1991-03-30 Научно-производственное объединение "Полимерсинтез" Method of cleaning air from toluylene diisocyanate vapors

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DERWENT ABSTRACT, Accession No. 92-070872/09, Class A88; & SU,A,1 637 846 (POLIMERSINTEZ RES), 30 March 1991. *
PATENT ABSTRACTS OF JAPAN, C-329, page 148; & JP,A,60 192 722 (KURASHIKI BOUSEKI K.K.), 1 October 1985. *

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