JPS5912325B2 - Filter manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter consisting essentially of a sheet structure obtained by coagulation of a polymer solution, and to a method for producing the same.

Laminated or sheet filters have been known for many years.

These materials consisted of woven, knitted or needle-stitched fibers of different lengths, which were additionally reinforced by adhesive or mechanical means.

As fiber materials, all kinds of materials, both natural or synthetic, are included within practical considerations.

However, all of these filters have more or less porous surfaces, which tend to become undesirably clogged by the particles being filtered.

Furthermore, although this initially allows for rapid filtration, in many cases this is not sufficient to provide total filtration, and the increasingly clogged filter area progressively becomes less effective.

Furthermore, the production of sheet structures by coagulation of polymer solutions has been known for some time.

It has also been known for a long time to produce microporous sheet structures, for example from polyurethane solutions, by coagulation techniques; As described for the manufacture of sheet structures,
The microporous sheet structure obtained in this way is permeable only to the gas phase.

The difficulty in producing these microporous sheet structures lies, in particular, in the inability to produce sheet structures with a smooth surface layer.

However, for thin sheet structures of up to about 400 microns, this is more achievable, but again requires complicated and time-consuming solidification techniques.

Typically, such processes involve immersion in a series of coagulation baths;
Moreover, the content of pure solvent must be gradually reduced in the soaking process.

This is because in many cases pregelation must be carried out sequentially and rapidly, otherwise incomplete microporization will occur.

One object of the invention is therefore to provide a microporous and/or visible pore structure obtained by coagulation, on the one hand, to be used as a membrane filter and, on the other hand, as a true filter, i.e. as a liquid filter. gender (macrop
orous) to create a sheet structure.

Another object of the present invention is that microporous and/or visually porous sheet structures of highly cross-linked polyurethane disstomers can be produced by coagulation techniques and, with appropriate post-treatments. The object of the present invention is to provide a process by which polyurethane solutions can be produced in a very simple and reproducible manner, with which the filters of the invention can be produced.

Other objects of the invention will be apparent from the description below.

According to the invention, the first object is to more or less abrade at least one surface of the microporous and/or visually porous sheet structure obtained by coagulation of the polymer solution, according to the desired pore size. This is achieved by

The starting point for this improvement is that the sheet-like structures produced by coagulation contain a special membrane structure, namely a perforated central layer surrounded by a very thin non-porous outer skin. That's what I discovered.

The central layer may have randomly distributed pores of various sizes, or the pores may be predominant with most facing outward.

Furthermore, these pores may be connected so as to form a capillary system, or they may each be independent pores in a somewhat larger number.

The second purpose of the present invention is to provide a special method for producing a polyurethane solution that is to become a microporous sheet structure made of highly crosslinked polyurethane, that is, a very simple and yet
This can be achieved using a highly accurate and reproducible method.

Furthermore, the microporous polyurethane sheet structures obtained by this method are particularly suitable for use as filters due to the abrasion treatment according to the invention.

The main object of the invention is thus a substantially microporous and/or visually porous sheet structure, in which at least one surface of the sheet structure is more or less porous according to the desired pore size. It is found in filters that are characterized by being abraded.

Furthermore, the invention relates to a particularly advantageous method for producing filters made of crosslinked polyurethane elastomers, which is characterized by the following points:

(a) making an NCO (incyanate compound) pre-adduct in a manner known per se and dissolving said pre-adduct in a suitable solvent, or making the NCO pre-adduct directly in the solvent, and then ( b) a suitable solvent and a pre-made solution of hydrazine and/or hydrazine derivatives and/or diamines and/or polyols (polyalcohols), provided that said compounds are
If the compound contains only two active hydrogen atoms according to 1nov), a compound containing at least three differently active hydrogen atoms according to Tserevitinov is additionally used),
A sufficient amount of NCO pre-adduct solution is mixed continuously for a specified period of time, during which the viscosity is constantly measured, and the viscosity is
Continue with the addition of smaller and smaller amounts of CO preadduct until the viscosity is constantly within a range of increasingly increasing viscosity, and finally until the viscosity reaches a certain level, then at the latest even with the addition of the smallest amount of NCO preadduct, the gel immediately (C) ceasing the addition of the NCO pre-adduct solution at the point at which oxidation occurs and carrying out the addition of the NGO pre-adduct solution at such a rate that the so-called "final solution" has a solids content in the range of 15-35% by weight. (d) leading the obtained highly viscous final solution to a coagulation bath after shaping with reinforcement material remaining in the filter, supported freely and/or on a support that can be removed later; and (e) abrading one or both surfaces of the resulting structure.

The solidification technique employed results in a sheet structure surrounded by a very thin non-porous skin layer and with a symmetrical or asymmetrical pore arrangement in the central layer.

When the doctor blade solidifies the polymer solution fed onto a smooth continuous base, an asymmetric pore array is formed, ie the pores are shaped like a funnel.

On the other hand, if a doctor blade coagulates a polymer solution applied to a reinforcing grid in which the reinforcing material is substantially embedded in the reinforcing grid in a freely supported relationship, the liquid in the coagulating bath will It acts to solidify from both sides so that the structure has a symmetrical arrangement of pores, ie a large number of tubular pores are formed perpendicular to the surface.

Symmetrical and asymmetrical hole arrangements can be illustrated by the accompanying drawings.

FIG. 1 schematically shows an enlarged cross-sectional view of a non-abrasive microporous sheet of the present invention having an asymmetric pore arrangement, and FIG. 2 a symmetrical pore arrangement;
1 schematically shows an enlarged cross-sectional view of a microporous sheet that has not been subjected to the abrasion treatment of the present invention.

In Figure 1, the imperforate cortical layer A represents the layer that has been exposed to the influence of the solidifying liquid, and the imperforate outer layer B constitutes the side that is in direct contact with the smooth object. This aspect therefore prevents the solidifying liquid from influencing the solidified layer.

In FIG. 2, the imperforate cortices A are substantially identical and both are equally exposed to the influence of the solidifying fluid.

Circle C indicates reinforcement. In the present invention, this extremely thin, imperforate cortex A and B is subject to abrasion.

Abrasion is performed on one or both sides, depending on the final purpose of the filter.

The extent to which the surface of the sheet structure is abraded can be determined by the degree of filtering effect to be achieved with the particular filter material.

Abrasion can be carried out by any known means, but is preferably carried out by wet milling techniques.

Further, the size of the pores can be adjusted by known means.

For example, the type of coagulation bath, the coagulation technique applied, and the addition of special pore control substances (such as the addition of organic acids such as formic acid), etc.

The asymmetric pore array filter material (ie, without reinforcement) produced by the preferred method according to the invention may be segmented if the filter material is required to be thinner.

In this case, the splitting takes place after the wear treatment.

Below we describe a preferred method of the invention for the production of polyurethane filter material, according to which method:
Owing to the high degree of crosslinking, it is possible to produce crosslinked polyurethane distomers such that, after conditioning, they are no longer completely soluble in the solvent used beforehand, without expensive capital investments.

The NCO preadduct used according to the invention is a high molecular weight compound with two NCO end groups, preferably 10
It has a molecular weight of 0 to 10,000, especially 800 to 2,500.

Preferably the NCO pre-adduct contains 1.5-5% NCO
It has a content of groups.

The production of these NCO pre-ducts is by well known methods.
This is carried out by reacting a high molecular weight compound containing H groups with an excess of polyisocyanate.

For example, angew manufactures this kind of NCO pre-duct.
andte Chemie (1952) pages 64, 523-531, Kunststoffe (1
(Published in 952) Pages 42, 303-310, West German Patent No. 831.772, West German Patent No. 897,01
No. 4, West German Patent No. 929,507, and US Pat. No. 3,000,757.

Preferably, the production of the NCO preadducts is adjusted in such a way that linear NCO preadducts with a narrow molecular weight distribution are obtained.

The question of which NCO preduct to use in each case depends on the particular system.

Because the N associated with chain growth agents and/or crosslinkers
This is because the reactivity of the CO preadduct largely determines the relationship between linear molecular weight and crosslinking.

High molecular weight compounds containing OH groups which are suitable for the production of NCO preadducts are, for example, polyesters, polyethers, polyesteramides, polythioethers and polyacetals.

Polyols for the production of NCO preadducts include, for example, polycondensation of epsilon (ε) caprolactone or 6-hydroxycaproic acid, containing primary and/or secondary and/or tertiary hydroxyl groups, or epsilon-caprolactone and dihydric Linear hydroxyl polyesters obtained by copolymerization with alcohols or by polycondensation of dicarboxylic acids and dihydric alcohols may be used.

The hydroxyl polyesters used in the preparation of the NCO preadducts can also be made from dicarboxylic acids or mixtures of dicarboxylic acids and dihydric alcohols.

Suitable dicarboxylic acids include, for example, adipic acid, succinic acid, speric acid, sebacic acid, oxalic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, phthalic acid,
Terephthalic acid, isophthalic acid, maleic acid, fumaric acid,
There are citraconic acid and itaconic acid.

Suitable dihydric alcohols or mixtures thereof which can be reacted with dicarboxylic acids or epsilon-caprolactone to form the desired hydroxypolyesters include, for example, ethylene glycol, propylene glycol, phthylene gelicol, and also, for example, 1,4-butanediol, Butynediol, butynediol, bis-(hydroxymethylcyclohexane), diethylene glycol, 2,2-dimethylpropylene glycol, 1,3-7'ropylene glycol carb.

However, all of the abovementioned diols may also be used alone.

This also applies to diamines or other low molecular weight compounds containing two hydrogen atoms with Zerevitinoff activity.

Suitable polyalkylene ethers with primary and/or secondary and/or tertiary hydroxyl groups which can be used according to the invention include alkylene oxides, water,
It is obtained by reaction with small amounts of active hydrogen-containing compounds such as ethylene glycol, phlopylene gelicol, amylene gelicol.

It is also possible to use alkylene oxide condensates of ethylene oxide, propylene oxide, butylene oxide, amidino oxide, styrene oxide and mixtures thereof.

It is also possible to use polyalkylene ethers which can be prepared from tetrahydrofuran.

According to the invention, any suitable polyester amide can be used to produce the NCO preadduct.

For example, reaction products of amines and/or amino alcohols with dicarboxylic acids.

Suitable amines are, for example, ethylene diamine and propylene diamine.

Suitable amino alcohols include, for example, 1-hydroxy-2-
It is amino-ethylene.

Any suitable polycarboxylic acid can be used.

For example, those already mentioned for the production of hydroxy polyesters.

It is also possible to use mixtures of glycols and mixtures of amino alcohols or polyamines.

Any of the glycols already mentioned for making hydroxypolyesters can also be used in making hydroxypolyesteramides.

According to the invention, it is also possible to use for the production of the NCO preadduct polyether ester polyols, ie polyols in which ester and ether bonds alternate.

These polyetherester polyols are described in Canadian Patent No. 783,646.

Preferred polyols for use in preparing NCO preadducts include polyols based on adipic acid, 1,6-hexanediol, and neopentane glycol with an average molecular weight of about 2
,000 polyester
0snabr uck Polyol2.002,
Hydroxyl number 56, acid number 1), polyester #(U
nion Carbide Corporation
N1ax Polyol D560) manufactured by BASF, and Polyol PT manufactured by BASF with an average molecular weight of 2,000.
There is MG polyether.

Furthermore, high molecular weight compounds with terminal carboxyl, amine and mercapto groups are also suitable.

Polysiloxanes with groups that react with incyanates should also be mentioned.

Further available compounds include, for example, J-H5a
unders*, co-authored by CFr1sch [Polyureta]
J (New York, 1962) Part 1, 33-61.
page, and in the literature cited here.

Any suitable organic diisocyanate can be used for making the NCO preadduct.

For example, aliphatic diisocyanate, aromatic diisocyanate, cycloaliphatic diisocyanate, heterocyclic diisocyanate, and also, for example, methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, cyclohexylene 1,4-diisocyanate, cyclohexylene 1,2-diisocyanate, tetra or hexamethylene diisocyanate,
Allylene diisocyanates, or their alkylated products, such as phenylene diisocyanate, naphthylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, di- or triisopropylbenzene diisocyanate, and also aralkyl diisocyanates, such as xylylene diisocyanate, fluoro-substituted incyanates, ethylene glycol diphenyl ether-2,2-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,1'-
Diisocyanate, piphenyl-2,4'-diisocyanate, piphenyl-4,4'-diisocyanate, benzophenone-3,3'-diisocyanate, fluorene-2,7-diisocyanate, anthraquinone-2,
6-diisocyanate, pyrene-3,8-diisocyanate, chrysene-2,8-diisocyanate, 3'-methoxyhexane diisocyanate, octane diisocyanate, omega, omega diisocyanate)-
1,4-diethylbenzene, omega, omega dash diisocyanate)-1,4-dimethylnaphthalene, cyclohexane-1,3-incyanate, 1-isopropylbenzene-2,4-diisocyanate, ■-chlorobenze2,4 -diisocyanate, ■-fluorobenzene-2゜4-diisocyanate, 1-tritetralobenzene-2゜4-diisocyanate, 1-fluorobenzene-
2,4-diisocyanate, 1-nitrobenzene-2,
4-diisocyanate, ■-chloro 4-methoxybenzene-2,5-diisocyanate, benzene-azonaphthalene-4,4-diisocyanate, diphenyl ether-2,4-diisocyanate, diphenyl ether 4
, 4-diisocyanate, and in addition, there are polyisocyanates containing isocyanurate groups.

Preferred diisocyanates for use according to the invention are 4,4-diphenylmethane diisocyanate and/or its 2,4-isomer and/or its 2,2
'-isomer, 1,6-hexamethylene diisocyanate, 2,4-toluylene and/or 2,5-toluylene diisocyanate and m-xylene diisocyanate.

The chain growth/crosslinking agent is preferably a substance containing unusually active highly active hydrogen atoms, such as those present in the NH2 group of hydrazine.

It is therefore preferred to use hydrazine compounds, especially hydrazine itself.

Chain growth may occur such that preferably about 60% of said NH2 groups are used for chain extension and the remaining 40% are used for chain crosslinking.

The reaction must occur simultaneously so that the addition of preadduct and the increase in viscosity occur proportionately.

In systems using chain growth/crosslinking agents of lower activity (compared to hydrazine, for example), the catalysis is maintained in a 60% to 40% relationship, where a constant number of crosslinks in the solvent The principle of the Flory reaction equation, which determines the extent of sited polymerization, should be exploited in a particularly advantageous manner.

In this connection, I would like to point out that “Po1yuretha
n: Chemistry and Technology
5under described on page 319 of vol. 2 technical edition
According to S and Fr1sch, the production of polyurethane distomers is particularly difficult when diamines are used as chain growers, since diamines easily produce non-homogeneous products due to their high activity. It means that there is.

However, the present invention exploits precisely this situation in order to obtain a homogeneous product.

That is, the high reactivity of hydrazine is carefully exploited to provide chain promotion and self-regulation of the degree of crosslinking, which occurs in solution and which, when properly stored, lasts for at least 24 hours.
It keeps it in a state where it can be poured over time.

To effect additional crosslinking, crosslinking reactions well known in polyurethane chemistry may be utilized.

Additionally, formaldehyde in polymeric form may be added to the crosslinker solution.

If formaldehyde in dimethylformamide and hydrated hydrazine are initially charged to the reactor, the first stage of the Wolf-Kitschner reaction begins and hydrazone is formed along with water.

However, under selected reaction conditions, the isocyanate-water reaction is significantly suppressed and the crosslinking reaction described below is promoted.

The amount of aldehyde added depends on the further use of the product.

The upper limit is the stoichiometric amount based on the NH group of the elastomer.

However, this crosslinking is different. This is because it occurs later at elevated temperatures such as occur during removal of the solvent.

Additional crosslinking can also occur when using unsaturated systems, these double bonds being broken by electron bombardment, thereby initiating localized branching reactions.

As mentioned above, substances suitable for the purposes of the invention are especially hydrazine compounds.

Examples include hydrated hydrazine, carbohydrazide, carbodihydrazide, semicarbazide, carbazone, oxalic acid dihydrazide, terephthalic acid dihydrazide, and dihydrazides of longer chain dicarboxylic acids, also with the general formula % BOR or S 102, where R is a fatty acid. represents a group group or an aromatic group.

is a dihydrazine compound.

In addition, there are compounds with a terminal amino group larger than Pipé.

Preferably the group R is an alkyl or allyl group.

Of course, in the method according to the present invention, the corresponding hydrate form may also be used, and hydrazine is preferable since it is less dangerous in handling.

By polyaddition of the NCO polymer with hydrazine or dihydrazine compound, -NH- group and -NH-NH
For example, polycarbohydrazides or polycarbodihydrazides or mixtures thereof are obtained with circular units partially crosslinked via - groups.

(PE-NH-CO-NH-NH-CO-NH]n.

(PE-NH-CO-NH-NH-X-NHCO, I
n.

(PE NH-CO-NH-NH-X-NHNH-Co
]n.

In the formula, ■ indicates a possible or adjusted bonding position with an adjacent polymer chain.

In these formulas, the abbreviation PE means polyester, polyether, polyamide, polythioether, polyacetal, and X is carbonyl, thiocarbonyl, sulfo,
Si02. BOR, P(0)OR or P(0)N
O3 group is meant, R is an aliphatic or aromatic group, and n is meant to mean that the final polyurethane contains more than one or more of the aforementioned units.

Suitable diamines for use according to the invention include, for example, ethylene diamine, propylene diamine, tolylene diamine, xylylene diamine, piperazine or piperazine hexahydrate, and also 1,4-diaminopiperazine.

As already mentioned, hydrazine, dihydrazine compounds and/or diamines may be used in deficit or in excess according to the invention.

If an insufficient amount is used, one more substance containing at least two groups with active hydrogen atoms is added to the prepared component solution, which may optionally be different from incyanate. can act as chain propagation agents and/or crosslinking agents, these substances being in excess after the stoichiometric reaction has taken place.

In both cases the excess can be up to 30%.

Suitable compounds of this type include all other chain growth or crosslinking agents commonly used in polyurethane chemistry.

For example, diols such as ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, butynediol, butynediol, xylene glycol, amylene gellicol, 1,4-phenylene-bis-, β-hydroxyethyl ether, 1,3
-phenylene-bis-β-hydroxyethyl ether,
bis-(hydroxymethyl-cyclohexane), hexanediol, and alkanolamines, also e.g.
Ethanolamine, aminopropyl alcohol, 2,2
-dimethylpropane, 3-amino-cyclohexyl alcohol, p-aminobenzyl alcohol, trimethylolpropane, glycerol or N,N
, N', N'-tetrakis-(2-hydroxypropyl)ethylenediamine.

Among all these substances, preference is given to using glycerol.

Of course, chain growth agents and/or crosslinking agents can be used simultaneously.

If desired, the solution containing the hydrazine-dihydrazine compound and/or diamine may be supplemented with a chain terminator and optionally an additional gel, in conjunction with, or instead of, a chain growth agent and/or crosslinking agent. It is also possible to add a curing agent.

Suitable chain terminators include, for example, monohydric alcohols, and also substances with amine groups, such as, for example, methyl, ethyl, furoyl, or butyl alcohol, or ethylamine.

Solutions containing the aforementioned hydrazine, dihydrazine compounds and/or diamines may be supplemented with organic or inorganic pigments, dyes, luminescent agents, UV absorbers, antioxidants, etc., prior to their reaction with the NCO pre-adduct filler. It is possible to add agents and/or additional crosslinking agents, in particular substances which carry out crosslinking only after coagulation at elevated temperatures.

However, in some cases it may be advantageous to add the above-mentioned additives not to the solution containing hydrazine, dihydrazine and/or diamine, but to the final polyurethane solution, optionally immediately before the production of the desired product. be.

Advantageously, the dyes which are soluble in the solution used are added shortly before shaping.

This is because a few types of dyes have an undesirable catalytic effect on the NCO pre-adduct.

A disadvantage of these dyes is that many of them fade as a result of the action of light.

It is therefore more preferable in some cases to use the pigments mentioned above.

Generally speaking, these pigments do not produce bright tones, but
It is certain that it is characterized by good covering power.

In addition, it has also been unexpectedly discovered that coloring promotes the microporous structure of the sheet material.

This has a positive effect on permeability.

If the pigment is selected appropriately, the amount used can be kept to a small amount.

Therefore, there is no danger that the elasticity of this system will be adversely affected in any noticeable way later on.

In the case of carbon black pigments, it is even possible to stably incorporate them into the pre-adduct by choosing suitable products with a certain number of OH groups.

It must also be pointed out that carbon black pigments are the best stabilizers against hydrolysis of such polyurethane systems.

The floating of the other pigments mentioned above can be avoided by the addition of so-called anti-floating agents.

A large number of pure fillers can be used.

Generally speaking, any non-reactive powdered or fibrous material can be filled, provided that in the case of films the length of the individual fibers is less than or equal to the thickness of the film.

This ensures that a thinner than normal coating provides a more uniform surface on the substrate material.

Of particular interest is the ability to precisely adjust the permeability of the filter material by incorporating microporous silica.

Moreover, these porous materials center the initial pores in the as yet uncoagulated film and provide effective assistance for the subsequent exchange of the non-solvent.

These have the function of both supporting the incoming non-solvent and receiving the displaced solvent.

This achieves faster solidification and more uniform microporosity.

On the other hand, it is also possible to use reactive additives.

It is also possible to some extent to use substances containing hydroxyl groups, such as cellulose powder or fibers, and to stably mix them as fillers.

These materials are particularly suitable for improving initial tear strength.

Furthermore, the surface characteristics of the microporous sheet structure can be changed by changing the fiber length.

Furthermore, if desired, flavoring substances such as coffee extract can also be mixed in.

Suitable solvents for the reaction components are, according to the invention, preferably organic solvents, especially highly polar solvents.

Examples of such solvents are aromatic hydrocarbons such as benzene, toluene, xylene, tetralin, decalin, and chlorinated hydrocarbons such as methylene chloride, chloroform, trichloroethylene, tetrachloroethane, dichloropropane, chlorobenzene, and esters such as succinic acid. Ethyl, propyl sulfate, butyl sulfate, diethyl carbonate, and ketones such as acetone, butanone-2,
pentanone-2, cyclohexanone, and ether,
Examples are furan, tetrahydrofuran, dioxane, anisole, phenethole, dialkoxyethane, and ether-esters of glycols, and acid amides such as formamide, dimethylformamide, dimethylacetamide, and sulfoxides such as dimethylsulfoxide.

Particularly preferred solvents for use include acid amides such as formamide, dimethylformamide, N,N-dimethylacetamide, and sulfoxides such as dimethylsulfoxide, dioxane, tetrahydrofuran, or mixtures thereof.

Although the NCO preadduct is dissolved in a solvent other than hydrazine, dihydrazine compound and/or diamine, the same solvent or solvent mixture is preferably used for both reaction components in the process of the invention.

For actual chain propagation and crosslinking reactions in which both occur substantially simultaneously, the NCO preadduct solution is added to the previously charged chain propagation/crosslinker solution with constant stirring.

The polyurethane forming reaction occurs as an exothermic reaction and terminates rapidly.

Chain promotion and crosslinking both result in increased viscosity.

The viscosity increases gradually at first and then suddenly increases rapidly.

During this stage of the process the NCO pre-adduct solution must be carefully added to the other ingredients.

This is because after a certain amount of addition, even the smallest addition of more NCO preadducts results in a severe increase in viscosity, and at some point in the process the reaction solution suddenly gels.

In accordance with the present invention, it has surprisingly been found that a significantly better polyurethane solution is obtained if the addition of the NCO preadduct is stopped once the viscosity of the solution has reached this level.

This level of viscosity is 6,0
It is within the range of 00 to 40,000 CPS.

In the practical operation of a preferred embodiment of the process of the invention, furthermore, 60 to 80 parts by weight, in particular 70 parts by weight, of the solids component and 1.5 to 5 parts of the free incyanate group component are added to 0.
．． hydrazine, dihydrazine compounds and/or diamines at a concentration of 0.02 to 0.05 mol % and at a rate such that the reaction solution has a solids content of 15 to 35% by weight at the point at which a rapid increase in viscosity occurs. In a solution of other ingredients contained,
Add continuously with stirring.

The amount of NCO preadduct added depends on many factors (temperature,
It is not possible to calculate this accurately, since it depends on the molecular weight of the polyester or polyether used for the preparation of the preadduct, the solid content of NGO groups, the material age of the preadduct.

It is therefore necessary to manipulate it experimentally.

The safest method is to first determine the approximate amount of preadduct needed in small-scale preliminary tests and then rely on the viscosity increase in the actual production of the final polyurethane solution.

In order to produce larger quantities of useful final solution or reaction solution, it is recommended to use flow meters that can reproduce the numbers found during preliminary tests.

However, according to the invention, precise adjustment is carried out in this case by means of a built-in viscometer.

The simplest recommended device for measuring viscosity is a falling ball viscometer.

This is because the accuracy is sufficient and cleaning is easy.

However, this device can only be used for non-pigmented systems.

If you want to color it, you have to do it after adjusting the viscosity.

Another method of determining viscosity is to measure the output of the stirrer motor using a suitable ammeter.

According to a particular method of implementation of the invention, preferably as NCO preadduct, a polyester (made from adipic acid and hexanediol-1,6) is obtained by reacting with 4,4'-diphenylmethane diisocyanate in dimethylformamide. Use what is given to you.

This NCO pre-adduct solution is added to a deficit solution of hydrazine hydrate in dimethylformamide, to which an excess of glycerol is added.

The reaction temperature is maintained at 20-45°C, preferably 25-40°C during the addition and reaction.

Generally, for the final polyurethane solution, before molding, all of the polyurethane is dissolved in the reaction solution, but after molding, it no longer dissolves in cold dimethylformamide to the extent of 50 wt., and in boiling dimethylformamide, 60 wt. The production is controlled to obtain a polymeric structure that does not dissolve to a greater extent than 100%.

The solution thus obtained is highly viscous, in a homogeneous pre-gelled state and may be stored for several days.

If one observes the indicated reaction conditions (temperature, solids content, time and appropriate ordering of the individual reaction steps), one finds that one is at the borderline between a solution and a gel and unexpectedly produces the nidistomer-like product described below. The final solution can be obtained reproducibly.

By selecting appropriate raw materials, physical properties can be tailored to specific end uses.

Optical properties can be determined during formation of the polymer structure without subsequent processing.

Suitable other gelling agents include, for example, solvents of the final reaction solution or solvents that are miscible with the solvent but are non-solvents for the crosslinked polyurethane formed.

Such non-solvents include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, tetralin, decalin, and industrial solvent mixtures containing aromatic hydrocarbons such as Sangajol.
), and aliphatic hydrocarbons, such as hexane, heptane, octane, nonane, decane, and their stereoisomers, and petroleum fractions, such as petroleum ether, ligroin, white spirit, terpinene substitutes, mineral spirits, and cyclic Aliphatic hydrocarbons such as methylcyclohexane, turpentine, and chlorinated hydrocarbons such as chloroform, dichloroethylene, trichloroethylene, hexachloroethane, perchlorethylene,
Chlorocyclohexane, methylchlorocyclohexane,
and ethers, such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, formate, and ketones,
Examples include acetone, butanone-2, pentanone-2, and ethers such as diethyl, dipropyl, dibutyl ether, and nitro compounds such as nitromethane, nitrobenzene, and alcohols such as tert-butanol, and nitrides such as acetonitrile.

Depending on the system used, the compounds listed here as nonsolvents may also act as solvents, and the solvents listed previously may also act as nonsolvents, so there may be some overlap in the above list. Some things are inevitable.

The final polyurethane solution produced according to the invention is used to produce microporous sheet structures by directing the high viscosity solution to a coagulation bath after shaping.

In principle, the abovementioned nonsolvents or mixtures of solvents and nonsolvents are used as liquids for coagulation.

For economic reasons, it is proposed in the present invention to use water without any additives as the liquid for coagulation.

Compared to conventional coagulation methods, coagulation according to the present invention')'' system ζ proceeds 10 times faster.

Of course, the structure obtained after solidification can be subsequently treated with the respective additive, provided that the corresponding additive is not present in the polyurethane solution prior to solidification.

The process of the present invention allows the production of microporous sheet structures with excellent mechanical properties, excellent flexibility, and solvent resistance that exhibit excellent filter effectiveness after abrasion.

Generally, the microporous structure is shaped into a suitable shape, for example in the form of a hose, and the final structure consists of two outer non-porous skin layers and a many times thicker inner microporous layer. can be processed directly.

It can be seen that the present invention has the following advantages over the prior art (in addition to those already mentioned).

1. Due to the asymmetric pore morphology, the filter has excellent flow velocity.

2. Easy to clean due to smooth surface.

3. The installed filter can be sterilized in steam without losing its shape.

4. The raw material used and the final product are physiologically safe.

5. Since the solvent can be reused, ecologically harmful corrosive liquids, solvents, etc. are not produced during production.

6. The final polyurethane solution can be molded onto any surface and structure.

7. The filter materials can be brought into close contact with each other.

Not only can it be used for new substances as industrial and household filters, but it can also be used as an industrial sheet for the following purposes.

1. Air can be purified and/or sterilized.

2 Gas can be expelled from highly viscous solutions.

3. When a partially transparent packaging material is required.

4. When destroying the emulsion.

The following examples serve to illustrate, but not limit, the invention.

In the examples, DMF is "dimethylformamide",
MDI is "4,4'-diphenylmethane diisocyanate."

Example 1 Conditioning of Polyol (Step 1) A weighed amount of polyol was charged into a stirred reactor equipped with a vacuum connection and a heating and cooling jacket and degassed and dehydrated for 30 minutes at 100° C./10 Torr. conduct.

Then it is cooled to 50° C. and o. 1% acetyl chloride is added.

The mixture is stirred at that temperature for 30 minutes, then heated to 100° C. and vacuumed until no further gas evolution occurs.

A sample is taken and the OH and acid value are measured using known methods.

The polyol thus prepared was adjusted with DMF to contain 700 parts by weight of solids.

Step 2) Charge a measured amount of MDI into a stirred reactor filled with dry nitrogen, and adjust to a solid of 70% with DMF.

This MDI rapidly dissolves into a clear solution by stirring and heating.

The stage 1 polyol with a temperature of about 55°C was heated to 40°C
Add to DI over 30 minutes.

The exothermic heat of reaction must be removed at 65±2°C.

The resulting pale yellow NCO pre-adduct solution has a residual NCO content of approximately 3.5%, depending on the molecular weight of the polyol.

Production of a solution containing cross-linked polyurethane (Ring-end solution) (Step 3) In a vacuum-sealed stirred reactor, 300 parts by weight of DMF,
10 parts by weight of glycerol and 2 parts by weight of hydrated hydrazine are charged and heated to 30±2°C.

The NCO preadduct with a temperature of about 40° C. is added continuously with stirring so that the viscosity of the final solution increases, first gradually and then at an increasing rate.

Finally, the addition of small amounts leads to extremely high increases in viscosity.

This occurs at approximately 10,000 centipoise.

The solution is then degassed. Molding and abrasion (stage 4) A solution containing the crosslinked polyurethane obtained from stage 3 (
"Final solution") was spread on a glass plate with a doctor blade to make a wet film with a thickness of 1w1, and this was
It was immersed in a heated water bath at 5.0°C.

After about 1.5 minutes, a white, elastic, microporous film was formed that was no longer completely soluble in the solvent used earlier.

The resulting film was then abraded on both sides to create a real filter.

Example 2 In a dry stirred reactor, a 70% solution of MD in DMF
2.04 mol of I are initially charged at 40° C. under a nitrogen atmosphere.

Over an hour and a half, 1 mole of a polyester consisting of adipic acid and hexanediol-1,6 with a hydroxyl number of 139.5 was dissolved in a 70% DMF solution at 65±2
Additions are made continuously at a reaction temperature of °C.

An NCO pre-adduct solution with an NCO content of 2.5-3° is obtained, which is stable for several weeks.

The NCO pre-adduct solution was added to 3,100 parts by weight of DMF and 50 parts by weight of water hydrazine at 35° C. in a stirred reactor equipped with a stirred mixer.
The addition is continued over a period of minutes until the point at which even the smallest addition results in an extremely high increase in viscosity, ie a final polyurethane solution of honey-like viscosity is obtained.

The final 30% polyurethane solution is processed into filters as described in Example 1.

Example 3 An NCO pre-adduct prepared as described in Example 2 was injected with stirring into a solution of 3,100 parts by weight of DMF, 200 parts by weight of glycol, and 50 parts by weight of water hydrazine; This is continued until the point at which even the addition of a minimum amount of more than 10% causes an extreme increase in viscosity, i.e., a highly viscous honey-like polyurethane solution is obtained, which is then applied to Example 1.
Process it into a filter as described in .

Example 4 A 70% solution of 2.04 mol MDI in DMF is charged to a dry, stirred reactor at 40° C. under nitrogen.

1 mole of polyester in a 70% DMF solution consisting of adipic acid and equimolar ratios of ethylene glycol and butanediol-1,4 with a hydroxyl number of 56 to 6
Addition is made continuously over half an hour at a reaction temperature of 5±2°C.

An NCO pre-adduct with a residual NCO content of 1.5-2.0% is produced and is stable for several weeks.

In a solution consisting of 3100 parts by weight of DMF, 90 parts by weight of carbodihydrazide and 100 parts by weight of methanol,
Addition of the minimum amount of NCO pre-adduct solution to the point where the viscosity increases rapidly, i.e., a highly viscous final solution is formed, is added with stirring and used to filter as described in Example 1. Process it into

Example 5 2.04 moles of MDI in 70% DMF are charged at 40° C. to a stirred reactor dried under nitrogen.

1 mole of a polyester consisting of adipic acid and hexanediol-1,6 with a hydroxyl number of 139.5 in a 70% DMF solution was heated at 65±2° C. for half an hour.
(continuously added at a reaction temperature of ).

The result is an NCO preadduct with a residual NCO content of 3.2%, which is stable for several weeks.

Approximately 165 parts by weight of the pre-adduct solution was mixed with OMF 30
0 parts by weight, 7.68 parts by weight of carbodihydrazide, and 10 parts by weight of glycerol, with stirring, to the point at which even the addition of the minimum amount causes an extreme increase in viscosity, i.e., a high viscosity final polyurethane solution. Continue until this occurs with a slight thermal effect.

This final polyurethane solution is stable for many days.

This final solution is processed into filters as described in Example 1.

Example 6 NCO pre-adduct solution (N
CO:NH2> 1) About 183 parts by weight, DMF 30
0 parts by weight, 2.5 parts by weight of piperazine, 0 parts by weight of water hydrazine
．． 8 parts by weight of the solution are added and continued until the point where addition of even more minimal amounts results in an extremely high increase in viscosity.

The resulting final polyurethane solution is processed into filters as described in Example 1.

Example 7 59.5 parts by weight of the NCO preadac described in Example 5 was injected into a solution of 100 parts by weight of DMF and 2.56 parts by weight of carbodihydrazide with stirring, and even with the addition of the minimum amount, the viscosity was extremely high. Continue until a certain increase occurs.

The final polyurethane solution obtained is processed into a filter in the same manner as in Example 1.

Example 8 Non-reactive pigments with particle size up to 5 microns and/or
Alternatively, Dye Part 10 (on a solid basis) is dispersed into the final polyurethane solution prepared as described in Example 2 and processed into a filter as described in Example 1.

Example 9 An NCO preadduct solution prepared as described in Example 2 or 3 is poured into a solution of 300 parts by weight DMF, 11.6 parts by weight of 1,4-diaminopiperazine and 10 parts by weight of glycerol with stirring, Addition of the smallest amount is continued until an extremely high increase in viscosity occurs.

The resulting final Polyurekne solution is processed into filters as described in Example 1.

Example 10 The procedure was as in Example 1, except that in step 3 the microporous silica was replaced by very finely ground coffee powder and/or coffee extract.

After coagulation and abrasion treatment, a light brown sheet structure is obtained, which is particularly suitable for brewing coffee and can be used many times.

Example 11 Example 1 was carried out similarly, using cellulose powder instead of silica.

After coagulation, a white microporous sheet structure is obtained, and after abrasion treatment an excellent filter is obtained.

Example 12 Similar to Example 10.11 or 12, reinforcing fibers of natural or synthetic highly polymerized polymeric materials or threads of metal wire were incorporated into the composition.

This is then coagulated in warm water.

Example 13 In Examples 1 to 12, the coagulation was carried out using a hot-temperature solution containing soluble salts and/or acids and/or bases and/or water-miscible and/or soluble organic solvents as pore control agents. Perform in aqueous solution.

Embodiments of the invention are listed below.

■) A filter made by the manufacturing method claimed in the patent.

2) Filters according to item 1) in which the reinforcing inserts are fibers of woven glass filaments.

-3) In the claimed manufacturing method, the solid content of the NCO pre-adduct solution is 60 to 80% by weight.
In particular, a manufacturing method using a material having a weight coefficient of 70.

4) In the manufacturing method of claim and/or item 3), the dissolved NCO pre-adduct is 1.5 to 5%.
A method of manufacturing containing free isocyanate groups.

5) In the claims and the manufacturing methods of items 3) to 4), in the solution containing the hydrazine and/or dihydrazine compound and/or diamine, the hydrazine and/or dihydrazine compound and/or diamine is added to 0. 02 to 0.05 mol %.

6) Process according to claims and one or more of paragraphs 3) to 5), in which the solvent used is a highly polar solvent, preferably an organic solvent, in particular dimethylformamide.

7) A manufacturing method according to claims and one or more of items 3) to 6), wherein the hydrazine solution used is a solution manufactured from water hydrazine and dimethylformamide.

8) If a hydrazine solution is used in the production process according to claims and one or more of paragraphs 3) to 7), the solution is heated at a temperature in the range from 20 to 40 °C, in particular at 2
A manufacturing method in which the reaction is carried out at a temperature within the range of 5 to 35°C.

9) In the manufacturing method according to claims and one or more of paragraphs 3) to 8), hydrazine and/or dihydrazine compounds and/or diamines are present in a stoichiometric excess relative to the isocyanate groups present. or used in insufficient amounts, and in the case of insufficient amounts, adding to this solution a substance containing at least two active groups with active hydrogen atoms that react (optionally with a specific reaction) with incyanate. and a manufacturing method in which the above substance is used in excess.

10) In the manufacturing method according to claims and one or more of paragraphs 3) to 9), hydrazine and/or
or dissolving in the solution containing the hydrazine compound and/or the diamine additional crosslinking substances, in particular substances that crosslink only after shaping at elevated temperatures, and/or other chain promoters and/or chain terminators;
and optionally additional gelling agents and to this solvent, prior to its use, fillers, organic, inorganic pigments, dyes, brighteners, UV absorbers, antioxidants and/or additional crosslinking agents are added. Manufacturing method.

11) A manufacturing method according to claims and one or more of items 3) to 10), wherein the coagulation bath comprises water.

12. A manufacturing method according to claims and one or more of items 3) to 11).

13) In the manufacturing method according to item 12), the reinforcing fibers are woven glass filament fibers.

14) A manufacturing method according to one or more of claims and items 3) to 13), in which the manufacturing steps are performed continuously.

15) Use of the filter according to one or more of items 1) to 14) as a liquid filter, in particular as a coffee filter.

[Brief explanation of the drawing]

FIG. 1 shows an outline of an enlarged cross-sectional view of a microporous sheet with an asymmetric hole arrangement and not subjected to the abrasion treatment of the present invention, and FIG. 1 shows an outline of an enlarged cross-sectional view of a microporous sheet that has not been subjected to A and B: cortical layer, C: reinforcement material.

Claims (1)

Claims: 1. A substantially microporous and/or visually porous sheet structure obtained by coagulation of a polymer solution, wherein at least one surface area of said sheet structure is more or less porous according to the desired pore size. A method for producing a filter comprising: (a) making an NCO pre-adduct and dissolving said pre-adduct in a solvent, or making an NCO pre-adduct directly in a solvent to obtain an NCO pre-adduct solution; and (b) A pre-prepared solution consisting of a solvent and hydrazine and/or hydrazine derivatives and/or diamines and/or polyols (provided that if said compound contains only two hydrogen atoms of active activity according to Tserevitinov, fewer hydrogen atoms of different activity according to Tserevitinov) (additional use of compound containing 3 in each case), a sufficient amount of said NCO pre-adduct solution is mixed continuously over a specified period of time, during which time the viscosity is constantly measured, and the viscosity is increased by addition of smaller and smaller amounts of NCO pre-adduct solution. Until it is within the range of constantly increasing the viscosity,
Continue until the viscosity finally reaches a certain level, then stop the addition of the NCO preadduct solution at the point at which instant gelation occurs with the addition of the minimum amount of NCO preadduct solution, and the final solution obtained is between 15 and 35 (c) adding the NCO pre-adduct solution at a rate such that it has a solids content in the range of % by weight; (c) said viscous final solution obtained is placed on and/or freely supported on a support from which it can later be removed; after being molded with a filler and/or one or more reinforcements inserted into the filter.
(d) drying the resulting microporous sheet structure; and (e) abrading one or both surfaces of the resulting structure. A method for producing a filter, characterized in that it is produced by a process comprising: