DE1923214B2 - PROCESS FOR THE SIMULTANEOUS PREPARATION OF PURE 4,4'-DIPHENYLMETHANE DIISOCYANATE AND A POLYPHENYL-POLYMETHYLENE-POLYISOCYANATE MIXTURE, POLYPHENYL-POLYMETHYLENE-POLYISOCYANATE, AND THE USE OF POLYPHENYL-POLYMETHYLENE-POLYISOCYANATE - Google Patents

Description

3 \ 5 4

methane diisocyanate and the trinuclear isomers result in isocyanate mixtures, is advantageous in relation to

l- (4-isocyanatophenyl-methyl) -3- (2-isocyanatophenyl- on space-time yield, acid, alkali and energy

methyl) -4-isocyanatobenzene (3 K 1) and 1,3-di- (4-iso consumption

cyanatophenyl-methyl) -4-isocyanatobenzene (3 κ II). The first step in the process, the distillation, is to understand what is set out below. Separation of a fraction A, ie a mixture of D's ratio of the 2,2-, 2,4'- and M'-diisocyanatodiphenylmethane determined by gas chromatography from concentrations the binuclear 2,4'- and 4,4'- the starting product, must. how the following isomers = α and the ratio of the concentration distillations are carried out in a way that the trivalent isomers 3 K 1: 3 K II = b which damage urocyanate groups. ₁₀ largely avoids heat. Suitable Appa-In a polyisocyanate mixture, as it is obtained by aniline rate continuously and in a vacuum with formaldehyde condensation and subsequent phosphorus-15 Torr-operated thin-film evaporator or fall-genation of the condensation product, film evaporator, via which part of the evaporated fluctuates depending the concentration of the starting materials material by means of centrifugal pumps several times vice-aniline, formaldehyde and acid catalyst, the i ₅ is circulated. According to the content of diisocyanate according to temperature control and pH value, at which up to 70% diisocyanate condensation occurs in the starting product, the ratio of ortho- and distilled off. The process can be carried out within wide limits via the length of the connection and the ratio of di-viscosity to viscosity of the concentrate depleted in diisocyanate, compounds with higher nuclei. of fraction B, control. The viscosity of the concentrate is largely independent of the above-mentioned reactants, depending on the amount of distillation conditions, but the ratio of the diisocyanate mixture remains between 200 and 10,000 cP / ratios a : b - K defined above. The value 25 ° C Concentrate B depleted in diisocyanate for K lies between 0.8 and 1.2 , 4'-isomers an- 25 methane anere; : hertes polyisocyanate mixture are biI-enriched, the ratio α is, however, reduction of sediment containing uretdione groups, at least by a factor of 1.3 greater than in the case of the non-distilled diisone obtained from the starting product. This has the consequence of cyanate mixture A in a multi-stage column that the factor K in the process according to the invention is fractionated under a reflux 0.5 to 1 to 20 to 1, according to the method, Uten Polyisocyanatge- 30 being referred to as the forerun Fraction C always mix above 1.3, generally between 1.4, preferably the 2,2'- and 2,4'-isomers pass over and and 3.0 is. a fraction D remains with the 4,4'-isomer. In addition to the polyisocyanate mixture defined in this way, a vacuum at the top is required for this distillation. The process according to the invention allows the column to require between 0.2 and 4 torr. Also, provision of at least 98 ° / _o sodium 4,4'-diphenyl-35 with the use of low pressure-loss columns diisocyanate. For example, those with fillers made of profiled The invention also relates to polyphenyl steel sheet or with spiral springs or with mesh polymethylene polyisocyanates, in which the wiring packing, as well as the low-pressure-loss evaporation ratio of the concentrations of 2,4'-diphenylmethane is a boiling diisocyanate in the bottom of the column to 4,4'-diphenylmethane diisocyanate = a 4 ° temperature above 150 ⁰ C, at which a decomposition and the ratio of 1- (4-isocyanatophenyl-methyl) - decomposition of 4,4'-diisocyanatodiphenyl imethane below 3- ( 2-isocyanatophenyl-r _l ethyl) -4-isocyanatobenzene is used to form carbodiimides. The bottom product ent-1,3-di- (4-isocyanatophenyl-methyl) -4-isocyanate always contains polymer E, benzene = b and a: b is greater than 1.3 after the fractionation, as well as the comparison with another Distillation using such a polyphenyl-polymethylene-poly- 45 thin-film or falling-film evaporator of pure isocyanate for the production of polyurethane paints 4,4'-diisocyanatodiphenylmethane is separated, with an increased pot life. The polymer E, usually less than 5 ° / ₀ of the starting product is an inserted shape of aniline and diisocyanate remains containing aldehyde produced polyamine mixture which liquid with more than 50 ° / ₀ of monomeric diisocyanate. There phosgene in an inert solvent, e.g. B. Chlorine 50 is - optionally mixed with first run benzene, is converted to the polyisocyanate mixture. and concentrate - for the production of poly-It is therefore not necessary to use two different urethane plastics.

Condensation products from aniline and formaldehyde, The fractionation of the diisocyanate mixture can

one for the production of 4,4'-diisocyanatodiphenyl can be combined with an iron chloride treatment, methane on the one hand and one for at room temperature 55 which has the purpose of chlorine-containing accompanying substances in one

to transfer liquid polyisocyanate mixtures with diphenylmethane non-volatile form. Before the fraction

structures on the other hand. column can also be provided with a still

The composition of the starting product will be switched to that at a vacuum between 3 and

a mixture of polyisocyanates of diphenyl 20 Torr is operated. This distillation is used to methane series, for performing method 60 removing residual solvent, whichever is better

not decisive. Technically easily accessible vacuum in the fractionating column would interfere,

Polyisocyanate mixtures with a diisocyanate content and as a residence tank for the action of iron

between 40 and 80% and a content of 2,4'-isochloride on the chlorine-containing accompanying substances at tem-

mers in the diisocyanate content between 1 and 40%. temperatures above 150 ⁰ C.

However, polyisocyanate mixtures with 65 are preferred.

50 to 70% diisocyanate and 4 to 8% 2,4'-isomers switch one another, with the following column

used in the diisocyanate portion. The production of overhead product from the preceding column

Polyamine mixtures, which send such poly- with phosgene and the sump to the inlet of the preceding-

5 6

is added to the column. This arrangement compares their pot life for the reason mentioned

leaves it, because the number of separating elements required for paints with a higher content of 4,4'-iso

units is distributed over several columns, each column is increased meren. Since the viscosity of the invention

with a lower pressure loss, that means lower, proper polyisocyanate mixtures due to the amount of

Bottom temperature to operate and the polymer 5 added 2,2'- or 4,4'-isomers are set

to reduce formation from isocyanate. can, the mixtures according to the invention provide

Continuous operation of all of these apparatuses is an interesting raw material for the production of foam expedient to represent the quality for the first run, pure substances, e.g. and to keep the polymer evenly. The flow behavior of the shapes is simple

Fraction C can be used to adapt, depending on the driving style. The manner according to the invention and the design of the columns, under gün polyisocyanate mixtures, are also suitable for the production ratios above 90% of the 2,2'-position of core sand binders, sealing compounds, and 2,4'-isomers>. in a single distillation coatings and other areas of application,
step can be separated. With such an enrichment, 4,4'-diisocyanatodiphenylmethane is poor in isomers, which in a column with more than 50 theoretical 15 is an excellent raw material for the production of elastic floors with a reflux ratio over shear fibers, homogeneous and microporous coating 10: 1 is obtained, however, the dwell time increases and elastomers,
and, mainly depending on the differential pressure

of the column, the bottom temperature and thus Example 1
Polymer formation and the loss of 4,4'-diiso-20

cyanatodiphenylmethane, so that ie distillation in a polyisocyanate mixture with

preferable columns connected in series is 3 _{50 /} i ^ '- diisocyanatodiphenylmethane,

Multiple fractionation allows the 2.2 and 59.4% 4,4'-diisocyanatodiphenyl methane,

2,4 -isomers can be obtained in more than 95% ratio. _{l2 0 /} i_ ₍₄ -l _S ocyanatophenyl-methyl) -3- (2-iso-

The fraction D freed from the polymer can, * « cyanatophenyl-methylH-isocyanato-

again depending on the driving style, on a benzene

Content of at least 99%, but 98%, 4,4'-di- _{20 6 0 /} i, 3-di- (4-isocyanatophenyl-methyl) -

Isocyanatodiphenylmethane are brought. Em Pro- '"4-i _socyana tobenzol

domestic product of this purity is, starting from aniline and _{g 6% Vierk} e _rni gen isocyanates
Formaldehyde, phosgenation of the condensation pro- 30

Duktes and distilling off the condensation product and a viscosity 100cP / 25 ° C is in one

tes and distilling off the diisocyanate, on the thin-film evaporator in a fraction A with

direct route not accessible 0.1% Z.r-diisocyanatodiphenylmethane,

To arrange the concentrate B with the pre- _{5 χ0 /} i ^ '- diisocyanatodiphenylmethane,
RunC it is possible to use concentrate B directly 35 94.70 / ₄ , 4'-diisocyanatodiphenylmethane
after its preparation in a container with the initial flow C from the isomer separation and a polyisocyanate mixture (fraction B) of the Viszufa'gen or separated continuously with that from the isosity 800cP / 25 ° C. The diisocyanate separation incurred flow C to mix mixture, to which 200 ppm iron (3) chloride are added and in this way the desired setting to 40 is mixed, runs continuously through an as received. Degassing called distillation, a fractionation

According to the method according to the invention, it is a column with an exchange height of 17 m and a nozzle

it is also possible to use only part of concentrate B with a layer evaporator.

Mix flow C and form a product. The degassing performed at a vacuum of 8 Torr

arrive, which contains more diisocyanate and is operated at a thin 45 and a temperature of 200 ⁰ C,

is more liquid than that used for the distillation serves to remove small amounts from the phosphor

Polyisocyanate mixture. generation process derived chlorobenzene. In the co-

The 2.2 'and lonne introduced by the flow C is at a vacuum at the top of 3 Torr

2,4'-Diisocyanatodiphenylmethane gives the mi and a bottom temperature of 210 ⁰ C and one

Schung properties that in many respects as a 5 ° reflux ratio of 4: 1 a fraction C, a

prove beneficial. Since in the starting product 4,4'-di-isomer mixture with 0.4% 2.2'-, 22.0% 2.4'- and 77.6%

isocyanate odiphenylmethane usually deducted the predominant 4,4'-diisocyanatodiphenylmethane,

This compound crystallizes for the purpose of evaporation with a

when cooling first. The exchange of 4,4'-lonne centrifugal pump is a partial flow of the

2,2'- and 2,4'-isomer improves the cold resistance 55 bottom product via a vertically arranged

age. pumped steam-heated tubular heat exchanger.

It is an advantage of the method that it allows a further partial flow to come from the same pump the isomer content in the process products is very even with a thin film, which is also heated with steam to a desired value, for example evaporator supplied in which a separation in wise 2,4'- in 4,4'-diisocyanatodiphenylmethane under 60 4,4'-dipheuylmethane diisocyanate (fraction D) and 1% within 0.2%, to be set precisely and a sump E takes place. The distillate is made using keep. a chill roll into a flaky product

In aromatic polyisocyanates ortho-permanent converted. According to gas chromatography, it contains

NCO group react with hydroxy compounds see analysis 0.6% 2,4'-diisocyanatodiphenylme-

slower than para-permanent NCO groups. Therefore 65 than, solidifies at 39.1 ⁰ C, its residual chlorine content is

those with 2,2'- and 2,4'-isora are suitable below 20 ppm.

enriched polyisocyanate mixtures according to the invention. The sump E, which is viscous at room temperature

very good for the production of polyurethane lacquers, is collected in a container and out of this

the polyisocyanate mixture, viscosity 8OOcP / 25 ° C, mixed in.

By adding 27 parts of fraction C from the fractionation column to 73 parts of the aforementioned polyisocyanate mixture B combined with sump E, the end product is formed with the following Evaluate analyzes:

Viscosity 205 cP / 25 C, 30.6 ° / ₀ NCO,

0.15% hydrolyzable chlorine, 0.39% total chlorine, 74 ppm iron,

7.4% 2,4'-diisocyanatodiphenylmethane, 53.2% 4,4'-diisocyanatodiphenyimethane, 1.1% 1- (4-1socyanatophenyl-methyl) -3- (2-hocyanatophenyl-methyl) -4-isocyanatobenzoI,

22.9% 1,3-di- (4-isocyanatophenyl-methyl) -4-isocyanatobenzene, tetranuclear isocyanates.

is brought with diisocyanate to a viscosity at 25 ⁰ C of 118 or 115 cP. In this back-mixing, a diisocyanate enriched with 2,4'-isomer and once a diisocyanate not enriched with S 2,4'-isomer are used:

6.5%

This isocyanate is mixed with a polyol foamed, which consists of 40% of a polyester with an OH number of 380, 30% of a polyether with an OH number 380 and 30% of a polyether with an OH number of 550.

The polyethers were obtained by reacting a tertiary alcoholic salt prophylaxis. The polyol blend also contains 3 percent by weight of a 50% strength aqueous solution of the Sodium salt of sulphurated castor acid, 1.2 percent by weight of a commercially available polyether siloxane and 1 percent by weight of a tertiary amine. 100 parts of the mixture «ground with 130 parts by weight of the The above isocyanates are reacted with the addition of 40 parts by weight of fluorotrichloromethane on an HK atomization machine 100 (Bayer system). Included the following reaction times are observed

Viscosity cP / 250 after distillation

of diisocyanate (= strain)

Blended with diisocyanate

ig A = without enrichment

B - with enriched

2,4-isomers

Ratio of strain to diisocyanate ... Viscosity of the mixture cP: 25 ° C

ao 2,4'-diisocyanate,%

4,4'-diisocyanate,%

3 core isocyanate I,%

3 core isocyanate II.%

V, ratio

as 2,4 '- / 4,4'- - = a

3 K 1/3 K II - b

away

Polyol component

Isocyanate mixture

No. 1 It

1250

63:37 118 15.2 38.9 0.9 19.2

0.391 0.047 8.3

63:37 115 2.2 50.3 0.9 19.3

Punching

Setting time Seconds

j rise time |

, 1200 parts by weight of a polyether compound prepared by reacting propylene oxide with trimethylolpropane with an OH content of 11.5% and a viscosity of 700cP (25 ⁰ C) with 2200 parts by weight of castor oil 1st pressing - OH content 4.8% - mixed into this mixture 500 parts by weight of sodium aluminum silicate of the zeolite type dispersed. The sodium aluminum silicate used has a water content of <2.5%

4 »The following are used as further components of the mixture:

Parts by weight

120

A closed-cell rigid foam with a density of 23 kg / m * is obtained, the remains dimensionally stable after long-term storage at -10 ° C

Example 2

In this example, two Porytsocyanatgemtsche 1 and II are used, which from a single, by aniline / formaldehyde condensation Polyammgemiscfa obtained and a polyisocyanate mixture obtained therefrom go out. By distilling off a ben amount of diisocyanate First, a distillate with a viscosity of 125 ° C measured at 25 ° C is produced, which is then mixed back

Titanium dioxide (rutile type) 800 Quartz powder (0.03 to 0.2 mm) 5300

This approach is homogeneous for 20 minutes and 10 minutes in a medium-sized stirrer degassed in a vacuum device at a pressure of 40 tons The product made in this way is öle Kofflpo * so I might think of a solvent-free

G

To check the processing time, 100 parts by weight are taken from the approach and with 23 § Polycyanate. A flowable one is obtained Mass that can be processed by potting «came within 24 hours to a hard art Material solidifies When using Poh / isocyanate ϊ This results in a delay of 70 minutes, when using not according to the invention Poh / isocyaaat Π, however, results in processing time of only 40 minutes.

Claims (3)

1 2 solid at room temperature and difficult to handle- claims: have, or the distillation is lossy if diamines improve the flow properties 1. Process for the simultaneous production of be left in the amine residue. pure 4,4'-diphenylmethane diisocyanate and a 5 Easier is to convert the polyamine mixture produced from aniline and formaldehyde polyphenyl - polymethylene - polyisocyanate mixture as a whole with phosgene from a polyisocyanate mixture, as it is converted into a polyisocyanate mixture and aniline-formaldehyde condensation and subsequent from 4,4'-diisocyanatodiphenylmethane phosgenation of the condensation product to be distilled off. The disadvantage of this process lies in the fact that it is obtained, the polyisocyanate mixture also the undesired higher-functional poly being first converted into an amine with phosgene by fractional distillation and as iso fraction A, which consists predominantly of isomeric cyanates or isocyanate derivatives, with diphenylmethane diisocyanates, and in an example carbodiimides and carbodiimide isocyanate fraction B, which apart from isomeric diphenyl adducts are lost in the distillation residue, methane diisocyanates more than two 15 A at least 98% pure 4,4'-diisocyanatoaromatic nuclei containing polyisocyanates diphenylmethane is not obtained in this way, is separated and then, because in the aniline-formaldehyde condensation, specific steps for fractionation and return - Diamines with ortho-NH ₂ , - the mixing position can be carried out, characterized in relation to the methylene group in the diphenylmethane that fraction A has a 20 skeleton - and 2,2'- and 2,4'-diisocyanato-fractionated distillation into one fraction C, diphenylmethane when a mixture is distilled which is converted from 2,2'-, 2,4'- and 4,4'-drphenylmethane together with the 4,4'-isomer,
diisocyanate, and in a fraction D, which The present invention now has a way of at least 98% of 4,4'-diphenylmethane for the production of pure 4,4'-diisocyanaiodiphenyldiisocyanate, and in a way of thermethane from The residue E amine mixture resulting from the phosgenation product of a polymerisation, as it is separated by condensation of and finally obtained from the frac- aniline and formaldehyde, whereby equal ions C and B and optionally the reverse from the phosgenation products the higher level E such mixtures are produced , functional polyamines valuable raw materials for producing which the ratio of the concentration 30 position of polyurethanes are obtained,
of 2,4'-diphenylmethane diisocyanate and 4,4'-di- The subject of the present invention is a phenylmethane diisocyanate = α and the ratio process for the simultaneous production of pure concentrations of l- (4-isocyanato-phenyl-4,4'- L> iphenyimethandiisocyanat and a polymethyl) - 3 - (2 - isocyanatophenyl - methyl) - 4 - isophenyl-polyrncthylen-polyisocyanate mixture from a cyanatobenzene and 1,3-di- (4-isocyanatophenyl- 35 polyiso ~ yanate mixture, like it by Aniline-formmethyl) -4-isocyanatobenzene = b and a: b is greater than aldehyde condensation and subsequent phosgene than 1.3. tion of the condensation product is obtained, 2. Polyphenylpolymethylene polyisocyanates, in which the polyisocyanate mixture initially by frakwelchen the ratio of the concentrations of ionized distillation in a fraction A, which 2,4-diphenylmethane diisocyanate and 4,4'-diphe- 4 ° predominantly from isomeric diphenylmethane diisonylmethane diisocyanate = α and the ratio of the cyanates consists, and in a fraction B, which concentrations of l- (4-isocyanato-phenyl-me- except from isomeric Diphenylmothandiisocyanaten thyl) -3- (2-isocyanatophenyl-methyl) -4-isocyanato- still from more than two aromatir. each have benzene and 1,3-di- (4-isocyanatophenyl-methyl) - the polyisocyanates, is separated and 4-isocyanatobenzene = b and a: b is greater than 1.3. 45 with specific steps for fractionation 3. Use of polyphenyl polymethylene and back-mixing! Polyisocyanate according to claim 2 for production, characterized in that fraction A by of polyurethane paints with a longer pot life. fractional distillation into a Fiaktion C, which from 2,2'-, 2,4'- and 4,4'-Diphenylmethandiisocycr. ^r U 50 consists, and in a fraction D, which at least consists of 98% 4,4'-diphenylmethane diisocyanate, and is separated into a residue E formed by thermal polymerization and finally 4,4'-Diisocyanatodiphenylmethane, a raw material for layers borrowed from the fractions C and B and optionally the production of polyurethane elastomers and the residue E, is made of 4,4'-diamino on an industrial scale, in which the Ratio of concentrate iodiphenylmethane obtained by reacting with phosgene in the form of 2,4'-diphenylraethane diisocyanate and ^ '- diinert solvents, mostly chlorobenzene. phenylmethane diisocyanate = α and the ratio of the starting product for the Dtatnin are aniline and the concentrations of 1- (4-isocyanato-phenyl-formaldehyde, from which by condensation in 60 methyl) -3- (2-isocyanatophenyl-methyl) -4-isocyanato-aqueous, hydrochloric acid solution a polyamine mixture benzene and 1,3-di- (4-isocyanatophenyl-methyl) -4-iso with the diamine as the main component. The cyanatobenzene = b and a : b is greater than 1.3.
Separation of the more than binuclear compounds in the process according to the invention as can take place at the level of the amine. The Destilla starting product used a polyisocyanate mixture tion of the polyamine mixture is due to the 65 different components can be determined quantitatively by high gas boiling temperature and chromatography at 92 ° C. For this The freezing point of 4,4'-diaminodiphenylmethane includes the binuclear isomers expensive, remaining polyamines in the residue are 2,4'-diphenylmethane diisocyanate and 4,4'-diphenyl