JPS5945695B2 - Polyelectrolyte composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to compositions useful in forming water-swellable articles of carboxyl-type synthetic polyelectrolytes.

U.S. Patent Nos. 3,669,103 and 3,670;
It is known from No. 731 that cross-linked polymeric absorbents can be sandwiched between flexible supports to obtain disposable diapers or dressings.

Furthermore, No. 2, 988, 539, No. 3, 393, 168
No. 3, 514, 419 and 3, 357, 067
It is known that water-swellable cross-linked carboxyl copolymers can be made from this paper. However, these prior art copolymers are all crosslinked during copolymerization or after polymerization with the formation of water-swellable polyelectrolytes that neutralize the subsequent carboxylic acid groups and thus these prior art copolymers are Polyelectrolytes cannot be cross-linked in situ as a coating on a substrate or as a flexible film thereof. The present invention comprises compositions useful for forming water-swellable articles of carboxyl-type synthetic polyelectrolytes comprising: (1) 5 to 60% by weight (based on solvent);
(2) at least 0.1% by weight (preferably not more than 10% by weight) based on the polyelectrolyte;
a cross-linking agent reactive with the carboxylate group of; and (
3) Characterized by containing a solvent of lower alcohol, water, or a mixture thereof.

Examples of these crosslinkers are polyhaloalkanols, amphoteric sulfoniums, haloepoxy alkenes, polyglycidyl ethers, bisphenol A-epichlorohydrin epoxy resins and mixtures thereof. In certain cases, such as making films or fibers, plasticizers such as cellulose ethers, cellulose esters, alkylene glycols, glycerin and mixtures thereof may be present in an amount of 10 to 50% by weight (preferably 15 to 50%) based on the polyelectrolyte. 25% by weight) is preferably included in the composition.

The present invention further relates to methods from which the compositions described above are heated on separate films, absorbent articles, granules, fibers and various substrates to temperatures above 30°C, and preferably from 900°C to about 150°C. including a method of making a product. The use of these high temperatures is advantageous in promoting cross-linking and drying of the polyelectrolyte. However, it is possible to omit the use of heat if desired. In order to obtain very high production rates of absorbent articles, it may be desirable to replace most of the water in the polyelectrolyte solution with a lower alcohol such as methanol or ethanol.

This substitution results in a lower solution viscosity at a given percent solids and facilitates drying. The final product of the invention is therefore water-swellable and useful whenever there is a need to absorb aqueous solutions.

Examples of various uses are surgical sponges, menstrual pads, diapers, meat trays, paper towels, disposable access mats, disposable bathroom mats, and disposable pet bedding. Examples of carboxyl synthetic polyelectrolytes useful in the present invention include homopolymers of acrylic or methacrylic acid and
Ammonium or alkali metal salts of one or more ethylenically unsaturated comonomers.

The only limitation is that any copolymer useful in making highly absorbent polymers according to the present invention must be essentially water-soluble in its salt form. Alternative copolymers of maleic anhydride and maleic acid and fumaric acid and esters are useful when made water soluble with a suitable base. One skilled in the art of free radical addition copolymerization will be able to create any suitable heteropolymers containing sufficient carboxylate functionality to render them water soluble and thus useful in the present invention. A list of applicable carboxyl polymers that can be made from readily available monomers and converted into their salt forms is as follows: Acrylic acid-acrylate copolymer Acrylic acid monoacrylamide copolymer Acrylic acid mono-olefin copolymer Polyacrylic acid acrylic acid monoaromatic vinyl copolymer Acrylic acid-styrene sulfonic acid copolymer Acrylic acid mono-vinyl ether copolymer Acrylic acid mono-vinyl acetate copolymer Acrylic acid-vinyl alcohol copolymer Methacrylic acid and all of the above comonomers Copolymers of maleic acid, fumaric acid and their esters and all of the above comonomers Copolymers of maleic anhydride and all of the above comonomers , can be sulfonated by treatment with chlorosulfonic acid or fuming sulfuric acid.

As indicated above, in many cases it will be desirable to add a plasticizer to the polyelectrolyte solution to soften the film or casting.

A disadvantage of using plasticizers is that many effective plasticizers are also wetting agents and make polyelectrolyte articles extremely sensitive to high humidity. For example, if a polyacrylate is converted to its corresponding acrylate and acrylate copolymer through alkaline ester hydrolysis, about 80% or more of the acrylate units (Mer) are converted before the polymer becomes water-soluble. There must be.

This is due to the attack of the alkali on the polymer particles from the outside, with the polymer molecules on the outside being modified more by ester hydrolysis than those inside the particles. At the high degree of hydrolysis required to make all polymers soluble, the resulting polymers are more similar to salts of polyacrylic acid than to polyacrylates. The flexibility of the original polyacrylate has been replaced by the glassy brittleness of the salt. This brittleness is highly undesirable for water-swellable (absorbent) articles. Formation of coatings and other highly water-absorbing articles that are flexible and therefore do not require the use of plasticizers by pre-treating polyelectrolytes of the type disclosed above, namely polyacrylates, in the following manner: It was further discovered that this is possible.

A preferred type of polyelectrolyte is a polyacrylate that has been previously treated by partial saponification of the alkyl acrylate units in the polymer chain. Thus, therefore, 30
Or 70 weight? If the alkyl acrylate units are left untouched in the polymer, the cross-linked article formed from the partially saponified polyacrylate solution is treated with a special water-soluble plasticizer such as glycerin. It is soft and flexible even without the addition of In this preferred method, the polyacrylate is made by partially saponifying the alkyl acrylate or a mixture thereof with an alkyl methacrylate with an alkali metal hydroxide solution before the final product is made. In general, the method for making this polyacrylate is to prepare (1) an alkyl acrylate in which the alkyl group has 1-10 carbon atoms, in an aqueous alkali metal hydroxide solution;
(2) 8 to 70% by weight of an olefinically unsaturated carboxylic acid, and (3) O to 15% by weight of an alkyl methacrylate, or a mixture thereof, having from of ω-hydroxy-alkyl acrylate having 1 to 4 carbon atoms in the hydroxyalkyl group is dissolved to form a polyacrylate solution having 30 to 70% by weight alkali metal carboxylate and this It is characterized by stages of heating the solution until saponification is complete.

A crosslinker is then added to the polyacrylate as disclosed herein. The alkali-soluble polyacrylates can be made by known techniques such as emulsion, suspension, bulk, or solution polymerization techniques.

Most preferably, an alkali-soluble latex having 15 to 60 weight percent non-volatile polymer solids is used.

Examples of useful alkyl acrylates are methyl acrylate, ethyl acrylate, propyl acrylate, hexyl acrylate and the like.

Examples of useful alkyl methacrylates are butyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate and the like. Examples of useful omega hydroxyalkyl acrylates are 2-hydroxyethyl acrylate, hydroxymethyl acrylate/3-hydroxypropyl acrylate and 4-hydroxybutyl acrylate.

The aforementioned polyacrylate is then dissolved in an aqueous alkali metal hydroxide solution.

Generally the equivalent weight of hydroxide solution used is 30 to 70% based on the molar concentration of polymerized monomer, and the desired amount is about 40 to about 55%. In either case, the amount of hydroxide solution added will convert or oxidize some of the acrylate ester to alkali metal carboxylate and neutralize the carboxyl groups of the polyacrylate used to form alkali metal carboxylate. The polyacrylate sufficient to do so and thereby converted will have from 30 to 70% by weight alkali metal carboxylate. The olefinically unsaturated carboxylic acids used in the present invention can be mono- or polycarboxylic acids.

Examples of monoolefin monocarboxylic acids are acrylic, methacrylic, crotonic, isocrotonic, angelica, tigrin, senecioic acid or mixtures thereof. Examples of mono-olefin polycarboxylic acids are maleic, fumaric, itaconic, aconite, terracon, citracon, mesacon, glutaconic acid.

Examples of crosslinking agents useful in this invention include 1,3-dichloroisopropanol; polyhaloalkanols such as 1,3-dibromoisopropanol; amphoteric sulfoniums such as tetrahydrothiophene adducts of novolac resins;
1,4-butanediol diglycidyl Ether, glycerin-1,3-diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, about 175 to about 3
There are polypropylene glycol glycidyl ethers having epoxy equivalent weights in the range of 80, bisphenol A epichlorohydrin epoxy resins having epoxy equivalent weights in the range of about 182 to about 975, and mixtures of the foregoing. Compounds containing two or more of the functional groups of the aforementioned crosslinking agents would be expected to be useful as well, and these functional groups under the conditions encountered in heating or drying polyelectrolyte solutions would be expected to be useful as well. The same applies to the precursors that form .

The cross-linking technique used in the present invention to convert soluble polyelectrolytes into insoluble but water-swellable polymers is known as nucleophilic substitution on saturated carbons.

Carboxylate ions on polyelectrolytes act as nucleophiles even though the crosslinker is a substrate for nucleophilic attack.

Typical leaving groups and their corresponding substrates are displayed in the table below.

A combination of any two or more of these leaving groups on the same substrate can act as a cross-linking agent for the polycarboxylate. The table lists some illustrative compounds used as cross-linking agents in the present invention and the limits of their use to obtain insoluble but highly swellable polyelectrolytes according to the present invention.

Once insolubility is reached, higher levels of crosslinker swell in the aqueous medium to give a tighter, less unstable gel, but a polymer of lower actual absorbency. The rate of nucleophilic substitution is concentration related and is a factor in this invention.

If the concentration of cross-linking agent in the composition is very low,
The reaction rate becomes quite slow (pot life before gelation is 10
-48 hours). Once the composition is applied to the substrate surface and solvent evaporation begins, the rate of cross-linking is accelerated. Adding heat at this point will further increase the reaction rate. The absorbent articles of the present invention may not be processable if the cross-linking reaction is driven by heating, aging, or excess cross-linking agent with the starting composition.

The composition becomes progressively more viscous and viscous until it spreads and forms a continuous gel that cannot be sprayed or spun. Examples of plasticizers useful in the present invention include methylcellulose, ethylcellulose, and Cellulose ethers such as cellulose acetate, cellulose butyrate and the like; alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol and the like; glycerin, diglycerin (2,3 polyethylene glycols having an average molecular weight of about 200 to about 400.

In a preferred method of making water-swellable films according to the present invention, the polyelectrolyte composition described above is spread on a flat plate or roller of metal, plastic, or other impermeable substrate and heated to a temperature above 30°C. Heating to a temperature cross-links the polyelectrolyte and drives off excess water and/or alcohol.

The film is then stripped from the plate or roller by a scraper to recover the complete film for subsequent storage or use. 5 In some cases it is desirable to add small amounts of surfactants to the polyelectrolyte composition to facilitate flow and aid in the removal of the continuous film from the water-impermeable substrate.

A secondary benefit of the use of surfactants is to increase the wettability of the dry final absorbent film product. Either anionic or nonionic surfactants can be used. Examples of useful surfactants are sodium alkylsulfonates and ethylene oxide derivatives of alkylated phenols and the like. Similarly, when absorbent articles are made, the article to be the substrate is coated with the composition and the coating is cross-linked.

It goes without saying that for the purposes of the present invention, a coating step means a complete coating or an intermittent coating, such as cellulose padded cotton, paper, woven or non-woven fabrics and the like. When a fibrous matrix is used as the substrate, the composition may be applied intermittently, i.e. in large spots, squares, or grid lines, to preserve the inherent flexibility of the fibrous matrix and at the same time improve its water absorption. It is possible to improve the properties widely. Plasticizers are not necessary in this case. The wood pulp can be coated as a slurry in the polyelectrolyte composition with subsequent swelling. If desired, the water-swellable film prepared as described above can be used by itself as the inner absorbent layer of a baby diaper.

It is often advantageous to break this film into flakes, strips or powder. This is accomplished by crushing or comminuting the film in a hammer mill, compounder or the like. If long flat strips are required, it is possible to cut the film into wide slices with a suitable slicer. In some cases, water-swellable fibers are desired.

These can be made by extruding the polyelectrolytes described above into a bath consisting of lower alkyl ketones such as acetone, methyl ethyl ketone, diethyl ketone, and the like. The alcoholic composition can be extruded into chlorinated hydrocarbons, i.e., non-monohydrous coagulants such as methylene chloride, perchlorethylene, and the like. This soft extruded fiber is then made into three or Remove from the bath by any convenient means such as a 5-roll cluster and roll approximately 30
above 70°C and preferably from about 70°C to about 150°C
The polyelectrolyte fibers are dried and cross-linked by passing them through a heated chamber to a temperature in the range of . The absorption capacity of the cross-linked polyelectrolyte (number 9 of the gelled solution per polyelectrolyte 19) is determined by the following method using synthetic urine (0.27N sodium chloride solution).

A 0.5 g sample of cross-linked polyelectrolyte is weighed into a 250 ml beaker, 0.27 N sodium chloride solution (150 ml) is poured into the beaker and allowed to soak for 2 hours at room temperature with occasional stirring.

The swollen polyelectrolyte is then collected by filtration and the gel volume is reported as 9 parts of gelling solution to 19 parts of polymer salt. The following examples are given for illustrative purposes only and are not intended to limit the invention.

Example 1 Poly(isobutylene-co-mono-maleic anhydride)
A solution of the disodium salt of was made in deionized water.

0.289 (8.7 wt % solids) of 1,3-dichloroisopropanol was added to 14.79 of this solution. 10 drops of a 2% solution of sodium lauryl sulfonate were also added therein. After leaving it for 40 minutes until the bubbles disappear,
This solution was spread on a clean polyethylene sheet with a 25 mil draw rod. When dry, the film separates from the polyethylene. The film is still water soluble after drying overnight. After 30 minutes at 60° C., the film absorbs 64 times its own weight of 0.27N NaCl without dissolving it.

After 1 hour at 100℃, the absorption capacity (gel capacity) was 1.
259 0.27 N NaCl per g, indicating that the cross-linking reaction was essentially complete.

Example 2 A 25% aqueous solution of poly(isobutylene-comaleate disodium) was prepared and this solution 109 was mixed with 0.29 (8%) epipromhydrin, 1 ml of water,
and 4 drops of 2% sodium lauryl sulfonate.

The film was stretched over Mylar, peeled from the Mylar sheet, and cured at 100 DEG C. for 2 hours. This film gave an absorption capacity of 56 g/9 in 0.27 N NaCl solution. Example 3 Example 2 was repeated using only 0.05g (2%) of epibromohydrin.

This film has a weight of 0.27NN, which is 76 times its own weight.
aC1 was absorbed without being dissolved. Example 4 Acrysol A-5 (polyacrylic acid, 25% solids in water) from R0hmandHass was neutralized with a stoichiometric amount of NaOH and 10 wt. of epibromohydrin and stretched the film onto Mylar.

After drying overnight at 85°C, this film has a 0.27NN
It gave an absorption capacity of 549/9 in aC1.

Example 5 Example 2 was repeated using 0.25 g (10 wt e solids) of epichlorohydrin as the crosslinker.

After drying overnight at 70°C, the film was 0.27NNaC.
It gave an absorption capacity of 929/9 in 1.

Example 6 1.0% by weight glycerin diglycidyl ether and 20% by weight MethOcelOMC25 (
Example 4 was repeated using methyl cellulose (having a viscosity of 25 cps for a 2% aqueous solution) as the plasticizer.

After drying overnight at room temperature, the film was grainy but flexible. After curing for 2 hours at 70°C, the film absorbed 33.69/9 of 0.27N NaCl and 2269/9 of deionized water.

Example 7 A 25% aqueous solution of poly(isobutylene-co-ammonium 1-half amide maleate) was mixed with 10% of glycerin diglycidyl ether (10% by weight based on polymer), glycerin (30% by weight of polymer), and 2% sodium lauryl sulfonate. Treated with drops.

The film was stretched onto a Mylar sheet and left overnight at room temperature. The absorption capacity of this film in 0.27N NaCI1 was 10.2 g solution/9 polymer. Example
8-14 Using various amounts of glycerin diglycidyl ether as a cross-linking agent instead of epibromohydrin and using 30% by weight based on the polymer? Example 2 was repeated using 10% glycerin as the plasticizer.

The film was stretched onto a Mylar sheet and cured overnight at room temperature. The results are shown in Table 1. The table shows the greater activity (efficiency) of glycerin diglycidyl ether compared to haloalkanols and haloepoxides.

Not only is a smaller amount required to efficiently cure the polyelectrolyte, but also curing occurs at room temperature. Example 15 An 8% aqueous solution of purif10cN-17 acrylamide-sodium acrylate copolymer was treated with 10% (by weight of the polymer) glycerin diglycidyl ether, 25% glycerin, 15 drops of 2% sodium lauryl sulfonate and the film was formed.

After drying overnight at room temperature and curing for 30 minutes in an oven at 80°C, this film gave a gel capacity of 159/9 in 0.27N NaCl. Example 16 109 of 25% solid poly(isobutylene-disodium comaleate), 10 drops of 2% sodium lauryl sulfonate, and 0.0.5! ! A laboratory paper towel was actually coated with an aqueous solution consisting of (2.0%) epibromohydrin.

When dry, this coating amounted to 36% of the total weight of the coated towel. This coated paper was rated at 14.3 in deionized water.
The untreated towel had an absorbency of 9/9 compared to 2.549/9. Example 17 Expanded polystyrene meat dish with 22% solids poly(isobutylene-disodium maleate) of 209 and 0.17 g
(4%) of dichloroisopropanol.

The weight of the coating after drying overnight was 0.79. 19
The coated dish for the volume of g solution/fl coated is 13.5
9 of 0.27N NaCl solution was absorbed.

Example 18 An ammonium monohemiamide salt of ethylene monomaleic anhydride copolymer (viscosity for 5% aqueous solution, 82 cps) was made into a 25% aqueous solution.

8.09 of this solution, 0.79 of glycerin, 0.05
9 (2.5 wt? solids) of glycerin diglycidyl ether, and 10 drops of 2% sodium lauryl sulfonate.

The solution was spread onto a Mylar sheet using a 15 mil bar and allowed to cure for two days at room temperature. This film is 1
It gave an absorption of 169 0.27N NaCl per 9 films. Example 19 The ammonium monohemiamide salt of styrene-maleic anhydride copolymer (173 cps for 5% aqueous solution) was treated as in Example 18 above.

This film gave an absorbency of 5.49/9 film in 0.27N NaCl. Example 20 Example 19 was repeated using only 1% by weight of polymer glycerin diglycidyl ether.

After curing overnight at room temperature this film was 13.29/9
of 0.27N NaCl was absorbed. Example 21 Methyl vinyl ether maleic anhydride copolymer (GA
15 of the disodium salt of FGantrezANl69)
% solids in aqueous solution and 3.3% as cross-linking agent
Example 18 using glycerin diglycidyl ether of
The film was made in the following manner.

After curing overnight at room temperature, the film absorbed 15.4 times its own weight of 0.27N NaCl. Example 22 Isobutylene maleic anhydride copolymer (15.49,
0.1 mol) was slurried in 200 ml of methyl alcohol and 1 ml of pyridine was added.

The mixture was stirred at 50° C. for 24 hours resulting in a clear solution. Polyethylene was precipitated in water, dried in vacuo and dissolved in dilute aqueous caustic solution to yield a 25% solution of the sodium salt of the copolymer's methyl half ester. This solution 10
29T for g! 19 (1.16% by weight) of glycerin diglycidyl ether and 10 drops of 2% sodium lauryl sulfonate and the solution was spread on a Mylar sheet with a 25 mil draw rod to make a film.

After curing overnight at room temperature, the polymer becomes insoluble and in 3529/9 deionized water and 39f! /g of 0.27N NaCl was absorbed. Set the cross-coupling level to 17η
(0.68 wt?), the resulting film absorbed 55.6 g/g of dilute salt solution and 7209/9 deionized water.

This same film absorbed the 279/9 salt solution after being placed in a 90°C oven for 30 minutes, so the crosslinking reaction was not complete. Example 23 An anhydride form of the copolymer was dissolved in calculated amounts of sodium hydroxide and water to create a 40% solids aqueous solution of poly(isobutylene-disodium comaleate).

209 of this solution was mixed with 0.49 (5 wt? polymer) of glycerin diglycidyl ether.

Fill the extrusion chamber (with a 3/4" x 21 pipe with a ball valve at the bottom and a hot tube outlet as the extruder tip) and add the dope vertically to a 12!' deep acetone condensation bath. Single fibers were piled up on the bottom of the bath and withdrawn at the end of the run. Nitrogen under a pressure of 25 psig was used to pressurize the spinning dope through the top of the extrusion. Dry at 100° C. for 2 hours. Later, the absorbency of the fibers was investigated.

It absorbed 289/9 synthetic urine (0.27NNaCl) and 1389/g deionized water. Example 24
Films were cast on Mylar sheets from a 25% aqueous solution of poly(isobutylene-disodium comaleate) prepared with 25% glycerin and 2.5% glycerine diglycidyl ether by weight of the polymer.

The film was cured for 1 hour at 80° C. and then equilibrated to 50% relative humidity in a room. The film was cut into strips, which were then cut into flat fibers approximately 2 m wide. The fiber rapidly absorbed 14 times its own weight in synthetic urine and 55 times its own weight in deionized water. Example 25 A 25% solid aqueous solution of the disodium salt of an isobutylene maleic anhydride copolymer was mixed with a few drops of 2% sodium lauryl sulfonate and a copolymer of the aryl amphoteric sulfonium disclosed in Example 3B of Patent No. 3,660,431. 5% by weight.

A film was formed and dried at 100°C for 13 hours.

The cloudy film absorbed 58 times its weight in synthetic urine and 300 times its weight in deionized water. Example 26 A film was made from a 25% aqueous solution of disodium isobutylene/maleic anhydride copolymer and 0.75% by weight glycerin diglycidyl ether.

After curing for 3 hours at 100°C, this film weighs 72g.
/g of synthetic urine was absorbed.

When this dry film is crushed into small pieces, it shows the same absorption rate and when ground into a fine powder in a crusher, it yields 74 g.
/9 Rapidly absorbed synthetic urine to the level of powder. Example
27-32 Poly(sodium acrylate-comethyl acrylate), a 7.5% aqueous solution of 80% sodium acrylate, was prepared by adding sodium hydroxide and diluting with water from a latex of poly(methyl acrylate).

Using various amounts of glycerin diglycidyl ether as a crosslinker, the films were stretched onto glass plates and cured in an oven at 125° C. for 1 hour. The results are shown in the table. The table shows that even though very little curing agent was required, the film did not become water swellable even after drying and heating in the absence of all this polyelectrolyte.

For a tight aqueous gel, at least 0.1% by weight is required, the exact amount depending on the polymer, cure, and end use. Example 33 A 25% aqueous solution of a 90/10 copolymer of sodium styrene sulfonate and sodium acrylate was prepared by heating the monomer solution at 50° C. overnight in the presence of 0.04% by weight K2S2O8 (potassium persulfate). I built it.

Eight grams of this solution was mixed with 75η (3%) glycerin diglycidyl ether and a film was cast onto Mylar. After drying in air for 2 hours, the film was picked up and placed in a 90°C oven for 1 hour. The gel capacity was 0.27N NaCl of 459/9. Example
34 Polyacrylic acid (ROhmandHaasAcrysO
A 25% solution of 1A-5) was treated with 1 equivalent of sodium hydroxide and diluted to 20% solids.

This solution of 109 was dissolved in D.I. in n-butanol. E. R87
800η of a 5% solution of D.36, 2% by weight relative to the polymer. E. R. 8736. D. E. R. 87
36 is 175-205 E. E. N. It is a diglycidyl ether of polypropylene glycol with a molecular weight of 250.

The film was cast onto a chrome plate, air dried for 3 days, and then cured in an oven at 150°C for 2 hours. This dried and hardened film (0.59) was mixed with 150ml of 0.27N
After dispersing in NaCl solution and permeating for 1 hour, the swollen polymer was collected on a 150 mesh sieve and weighed. This gel has a weight of 419 and a polymer of 19
It had an absorption capacity of 829 per cent. Example 35 Poly(ethylene-monobutyl co-maleate) MOO8
A 50% aqueous solution of antOEMA3l22 was treated with 1 equivalent of sodium hydroxide and diluted to 25% solids.

This solution was prepared as in Example 33 at 1.5% D. E. R
8736 and a film was made and tested.

The absorbency was 399/19 polymer. Example 3
6-44 Three mixtures were made with the following compositions.

*Dioxotyl sodium sulfosuccinate.

Part A was placed in a 21 reactor and warmed to 40° C. with a vigorous nitrogen flow. 18ml 10) Part B was added to the reactor followed by the entire amount of Part C.

The remainder of Part B was added over an additional 2.5 hours while maintaining the temperature at 39-41°C. The latex was then steamed at 60°C for 1.5 hours, cooled to 30°C and stored in bottles. This latex contained 40.6% non-volatile content by weight. The above latex 11259 was added in small streams over 25 minutes to a gently stirring solution of 187.169 in 50% NaOH in 547.99 deionized water.

After all the polymer was dissolved, the viscous solution was aged at 50° C. for 22 hours to completely saponify it. The resulting solution (2
5.4% solids) has a Bruckfield viscosity of 16,200 cps at 25°C (5 spindles, 10 rpm).
It had The polymer was 50% ethyl acrylate by mole and the remainder acrylic acid and sodium methacrylate. D. a sample of the above solution. E. R. 8736 epoxy resin and cast with a 25 mil draw bar onto polished chrome board.

After air drying, the film was removed from the board and
It was placed in the oven for 2 hours after zero. 0.27 of various films
The absorption capacity (gel capacity) in NNaCl is shown in Table V. D. E. R. O736 is first dissolved in 29 g of acetone and then dispersed in 8 g of a 25% polymer solution. The table lists epoxy resins that are essentially water-insoluble. In Case of,
Explain the need for a co-solvent or a carrier such as acetone to obtain sufficient cross-linking with high levels of curing agent.

At very low levels, the epoxy resin alone can be dispersed and reacted efficiently. Example 45-52 D. E. R. The method of Examples 36-44 was repeated using a 20% aqueous dispersion of 661 (a bisphenol A-epichlorohydrin epoxy resin having an epoxy equivalent weight in the range of 475-575).

The films thus made were tested in a similar manner. The results are shown in the table. The table shows the performance of solid, water-insoluble epoxy resins.

Without this solvent, the resin and polymer electrolyte would react only on the surface of the resin particles, which would be extremely inefficient.
After swelling in a co-solvent, the cross-linking efficiency is significantly improved. Examples 53-61 The method of Examples 36-44 was repeated using diglycidyl ether of neopentyl glycol as the curing agent.

The results are shown in the table. *DGENG is neopentyl glycidyl ether.

Examples 62-68 The method of Examples 36-44 was repeated using diglycidyl ether of 1,4-butanediol (4) GEBD) as Cole's jig hardener.

The results are shown in the table. EXAMPLES Three mixtures were made with the following compositions.

*Dioctyl sodium sulfocinate (TritO
nGR-5).

Part A was placed in a 21 reactor and warmed to 40° C. with a vigorous nitrogen flow. Part B of 18d was added to the reactor followed by all of Part C.

The remainder of Part B was added over an additional 2.5 hours while maintaining the temperature at 39-41°C. The latex was then steamed at 40°C for 15 hours, cooled to 30°C and stored in bottles. This latex contained 39.5% non-volatile content. The 4009 latex prepared above was dissolved in 1209 deionized water with 209 sodium hydroxide at 75°C.
Mix to make a 30% polymer solution, which is 31.
It was 4% by weight of acrylic acid and sodium methacrylate. 30η of glycerin diglycidyl ether (1.0% curing agent based on the weight of the polymer) was mixed into the above solution 109. The sheets were cast onto mirror-finished chrome plates using a 25 mil drawbar, air dried, and oven cured for 15.5 hours at 70°C and 0.5 hours at 90°C.

This polymer sheet absorbed 23 times its own weight of synthetic urine (0.27NNaCl solution) in the absorption capacity test described above. Examples 70-75 Example 69 with varying amounts of sodium hydroxide and curing agent
The method was repeated.

The results are shown in the table together with Example 69. These examples show that there is an inverse relationship between softness and suction power.

The best all-around good products of these examples are about 50
% residual acrylic ester and approximately 0.15% by weight. is cross-linked with glycerin diglycidyl ether. Example 76 Example 69 was repeated using the monomer mixture below and less initiator and without the mercaptan chain terminator to increase the molecular weight.

Polymerization was carried out at 60°C and yielded a latex with 40.6% non-volatile content. 1125 g of the above latex was added in a trickle over a 25 minute period to a gently stirred solution of 187.169 ml of 50% NaOH in 547.99 ml of deionized water.

After all the polymer has dissolved, the viscous solution is heated to 55°C for 22 hours.
Saponification was completed by heating for some time. The resulting solution (
25.4% solids) has a Bruckfield viscosity of 16,200 cps (No. 5 spindle, 10 cps per minute) at 25°C.
rotation). The polymer was 50% ethyl acrylate by mole and the remainder acrylic acid and sodium methacrylate. 32g of the above solution was mixed with 16W9 (0.
2% by weight) of glycerine diglycidyl ether and cast onto polished chrome board with a 25 mil draw bar. After air drying, the film was removed from the plate and placed in a 150°C oven. 0 after 20 minutes curing
．． The absorption capacity (gel capacity) of this film in 27NNacl was 64 g solution for 19 polymers.

The film was strong and flexible straight out of the oven and required creases to tear. Example 76
8 grams of the saponified solution prepared in Example 76 were mixed with various amounts of 1,3-dichloroisopropanol and films were cast and cured from these mixtures in the manner of Example 76.

The gel capacity of this film is shown in Table X. These examples are from D. C. I. P. indicates that the optimum level of crosslinker used is close to 0.5% by weight of the polymer to be cured.

Examples 81-88 Example 7 to vary the content of sodium acrylate
The latex of Example 76 was prepared and saponified by the method set forth in Example 7, with varying amounts of sodium hydroxide.

8f of each solution! were formulated with different amounts of glycerin diglycidyl ether. The film was then cast onto a polished chrome plate, air dried for 14 hours, and heated in an oven at 150°C.
It was cured for 2 hours. The absorbency was measured as described above and the softness at 45% relative humidity was recorded. These results are shown in Table M. These examples show that the unconverted ethyl acrylate portion of the copolymer can be increased to 52 mole percent without significant loss in absorbent capacity and a desirable soft product is obtained.

Example 89 Three mixtures were made with the following compositions.

Part A 2309 Deionized water 0.39 Trit0nGR-5 1.09 Na2S208 (sodium persulfate) 10.0
9 Itaconic Acid Part B 209 Methacrylic Acid 170 g Ethyl Acrylate Part C 70 fl 1 Deionized Water 1.259 NaHS03 Part A was placed in a 21 reactor and heated to 60° C. under a vigorous nitrogen flow.

Then 20ml (7) part B was added followed by all of part C. The remainder of Part B was added continuously over 1 hour at 60°C. The latex was cooked at this temperature for 1 hour to yield a final latex with a non-volatile content of 40.6%. 1009 of the above latex was then mixed with 50% aqueous sodium hydroxide and 49.1 fl of deionized water and heated at 55° C. for about 10 hours to give 52 mol. A 25% solution of polyelectrolyte containing ethyl acrylate was given. This polyelectrolyte was also calculated to have:
51 weight? 30% by weight of ethyl acrylate and 12.3% by weight of sodium acrylate? 6.5% by weight of sodium methacrylate
20 g of the above polyelectrolyte disodium itaconate was added to 45 g of water and 7.59 g of the above polyelectrolyte.
(0.15%) of glycerin diglycidyl ether.

The film was cast onto a mirror finished chrome plate using a 25 mil drawbar and the film was air dried at room temperature for 6.5 hours and then cured in an oven at 150 DEG C. for 16.5 hours.

The absorbency of the final cured film was 419 for 19 polymers in the above absorbency test with synthetic urine.
Example 89 shows that the polymerization recipe and method can be varied significantly but still allow the production of superabsorbent polymers.

Aspects of the present invention and related matters will be listed.

(1) The composition according to claim C, which also includes 10% to 50% by weight of a soluble plasticizer based on the polyelectrolyte.

(2) ◆ 5 to 60% by weight, based on the amount of solvent, of a carboxylic polyelectrolyte or a mixture thereof. At least 0.1% by weight, based on the polyelectrolyte, of a soluble cross bond reactive with carboxylate groups. b) forming a coating or fiber from the solution; and heating such coating or fiber to cross-link the polyelectrolyte; A method of making a water-swellable polyelectrolyte coated film or fiber, characterized by the step of removing excess solvent.

(3) The composition according to the claims or the above-mentioned composition, wherein the cross-linking agent is a polyhaloalkanol, an amphoteric sulfonium, a haloepoxyalkane, a polyglycidyl ether, a bisphenol-A-epichlorohydrin epoxy resin, or a mixture thereof. The method described in (2).

(4) The composition as claimed in the claims, wherein the carboxyl polyelectrolyte is a partially saponified polyacrylate solution, or the method as described in paragraph (2) above, in which the solution is impermeable in step (5) b). 2. The method of item (2) above, wherein the film is formed comprising the additional step of spreading the polyelectrolyte film on a polyelectrolyte substrate and separating the cross-linked polyelectrolyte film from the substrate.

(6) The method of item (5) above, comprising the further step of disintegrating the film to form flakes, strips or powder thereof.

(7) A water-swellable film produced by the method described in item (2) above.

(8) An article having a water-swellable coating produced by the method described in item (2) above.

(9) The article according to paragraph (8) above, wherein the article has a natural or synthetic fibrous matrix.

(10) Item (8) above, wherein the article is a foamed polymer.
Articles listed in ).

In step (1b), the solution is extruded into a bath consisting of lower alkyl ketone or chlorinated hydrocarbon to form extruded fibers, and the extruded fibers are separated from the bath to form fibers. ).

(0 Water-swellable fibers produced by the method described in item (2) above.

Claims (1)

[Claims] 1 5 to 60% by weight of a carboxyl polyelectrolyte or a mixture thereof, based on the amount of solvent; 2 At least 0.1% by weight of a soluble crosslinker reactive with carboxylate groups, based on the amount of polyelectrolyte. 3. A carboxyl synthetic polyelectrolyte composition useful in forming water-swellable articles, comprising: a binder; and 3. water, a lower alcohol, and mixtures thereof.