JPS63159413A - Production of water absorbing flexible article - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION SUMMARY OF THE INVENTION A method of making a flexible article for water absorption is provided, which comprises the reaction of an olefinically unsaturated carboxylic acid, an alkyl acrylate, and a small amount of a crosslinking agent, all in specific ratios. It is carried out using a polymer containing product.

FIELD OF THE INVENTION The present invention relates to flexible articles for absorbing water.

Various methods have been proposed for producing water-swellable and water-insoluble polymeric materials. Materials of this type are prepared from polymer-forming compositions containing carboxyl groups by polymerization of monocarboxylic acids in the presence of crosslinking agents. Monopods of this type include acrylic acid, maleic acid, maleic anhydride, and the like. Linear carboxylic acid polymers of this type include acrylic acid-acrylate copolymers, acrylic acid-acrylamide copolymers, and acrylic acid-olefin copolymers. U.S. Patent No. 3,980,663 discloses a water-soluble, low molecular weight polyelectrolyte containing nucleophilic carboxyl ions, which has two or more sites that are subject to nucleophilic attack by carboxyl groups. The preparation of this type of polymer by reaction with a crosslinking agent is disclosed. This method is exemplified by the reaction of a sodium salt of an acrylic acid-methyl acrylate copolymer crosslinked with glycerine diglycidyl ether in an aqueous solution (prepared by adding sodium hydroxide to the latex of the copolymer). be done. The resulting product is cast into a film and cured in an oven for 1 hour. However, this method and product have various drawbacks. The crosslinking reaction is slow and requires particularly large dryers to provide the residence time necessary for curing. moreover,! i'' bridges are achieved by forming diester bridges between linear polymer chains. This bond is subject to hydrolysis and thus polymer degradation. Another disadvantage of this patent is that milling reduces the This results in a product with a low surface area/weight ratio inherent in slow water absorption films, which means that the swollen surface of the film absorbs more water during the absorption test. The core of the film therefore exhibits only slow, if any, swelling capacity.

Other polymeric systems have also been proposed with particular regard to the formation of water-swellable, water-insoluble materials that can absorb large amounts of water without disintegrating or solubilizing. Journal of Applied Polymer Science, Volume 14, Nos. 897-92
8 (1970) entitled "Mechanism of alkaline thickening of acid-containing emulsion polymers",
Burbrook states that acid-containing latexes undergo a swelling process common to all neutralization steps to become completely solubilized and become more hydrophilic polymers.

Burbrook uses the general formula methyl methacrylate/ethyl acrylate/methacrylic Il in a polymer of luck.
A specific neutralization reaction is described that changes the Tg and hydrophilicity of i (MMA/EA/MAA) and changes the ratio of MMA/EA from 5010 to O/80. Both viscosity changes and macroscopic changes observed under an optical microscope were observed. Also, studies on monomers with larger hydrophilic ranges, e.g. 80/20 and 70/30 EA/M
Studies have also been disclosed using high EA/MAA contents such as zero MMA in AA. Optical microscopy showed that the particles gradually swelled as the carboxylic acid groups were gradually neutralized.

It is disclosed that at 80% neutralization, the particles become highly swollen and a phase change from solid to liquid medium becomes discernible. At 90% and 100% neutralization, the particles disappear and a genuine solution is formed. Polymer latex particles with low hydrophilicity, such as high MMA levels and low EA and MA
A level (e.g. 60/20/20 MMA/EA/
MAA) becomes a viscous gel upon neutralization and is visible under an optical microscope as slightly discernible swollen gel particles, with no clear boundary between the swollen particles and the solution. Electron microscopy of dry, 100% neutralized latex particles shows many tentacles protruding from the central core, which wrap around the particles, ie, stick to each other, resulting in high viscosity. Additionally, Burbrook discloses the preparation of four EA/MAA copolymers that are highly crosslinked with ethylene glycol dimethacrylate at 15% and 30% levels. MAA content is 20% and 30%. Latexes prepared with 15% crosslinking swell upon neutralization, resulting in much higher viscosities than those obtained with uncrosslinked polymers.

The 30% crosslinked material exhibits neither swelling nor viscosity due to its extremely high crosslink density.

The water-absorbing flexible article of the present invention is comprised of a specific short chain monomer that is improved over conventional water-JIB-wettable, water-insoluble polymer-forming compositions in combination with a biological cross-linking agent. Manufactured from polymers.

When polymerized and neutralized, the composition forms an absorbent product that, when swollen, has a dry-to-feel.
-the-touch feel). Combined with the extraordinary retentiveness of the absorbent to absorbent fluids, this is of importance in the production of flexible articles for water absorption according to the invention, such as surgical and dental sponges, menstrual tampons, diapers, inflatables, etc. It is important in a variety of articles such as paper towels and disposable litter mats for livestock pets.

In view of the above, the polymer-forming composition for use in the present invention comprises (a) about 15 to about 50 weight percent olefinically unsaturated carboxylic acid; and (b) about 49.07 to about 82 weight percent alkyl. A crosslinking agent consisting of an acrylate (wherein the argyl group has 1 to 6 carbon atoms) and (C) a monomer having about 0.03 to about 3.0 weight n% of two or more polymerizable ethylene groups. It is characterized by and .

Additionally, polymer salts useful as water absorbing agents are used, which polymer salts are formed from the polymers formed from the composition as suspension polymerization reaction products of composition components (a), (b), and (C). Characterized by salt.

Preferably, the polymer salt is a polymeric alkaline salt or an organic amine salt. Examples of alkaline salts can be selected from sodium, potassium, lithium and ammonium. Examples of organic amine salts can be selected from trimethylamine and triethanolamine.

In producing the polymer used in the present invention, a mixture of monomer B containing an olefinically unsaturated carboxylic acid and an alkyl acrylate is polymerized in the presence of a small amount of a vinyl crosslinking agent. Crosslinking is accomplished by introducing the vinyl groups of the crosslinking agent directly into the carbon-carbon backbone of the polymer. If long-term disintegration resistance is required, hydrolytically stable crosslinkers,
For example, divinylbenzene or triallyl cyanurate can be used.

Useful olefinically unsaturated carboxylic acids are those materials that have an activated olefinic carbon-carbon double bond and at least one carboxyl group, ie, acids that have olefinic double bonds. Representative examples of suitable carboxylic acids are acrylic acid, methacrylic acid, ethacrylic acid,
Includes compounds such as crotonic acid, muconic acid, aconitic acid, and mixtures thereof. Preferred carboxylic acids are acrylic acid and methacrylic acid.

Useful alkyl acrylates are those in which the alkyl group has 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Representative examples of suitable acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate and isobutyl acrylate. Preferred acrylates are methyl acrylate, ethyl acrylate and n-butyl acrylate, methyl acrylate being particularly preferred. Larger chain acrylates tend to be more hydrophobic, such that the final polymer salt exhibits lower swelling and water absorption in water and aqueous salt solutions.

Other monomers that do not fall within the scope of the monomer description above may also be used in small amounts, i.e. up to about 8% D by weight, as long as they do not adversely affect the basic and novel properties. I can do it.

For example, acrylamide, 2-ethylhexyl acrylate, hydroxyethyl acrylate and hydroxyethyl methacrylate can be used as partial replacements for methyl acrylate-1- or ethyl acrylate, and itaconic acid, maleic acid or maleic anhydride can be used as methacrylic acid. It can be used as a partial replacement for acid or acrylic acid.

The crosslinking technique used to convert water-soluble polymers into insoluble, water-swellable polymers is free! This is well known as llt group addition polymerization. Crosslinking agents that can be used are polyunsaturated polymerizable vinyl monomers having two or more free-radically polymerizable ethylene groups. Virtually any monomer having two or more polymerizable ethylene groups can be used, provided that the monomer is capable of entering into vinyl addition polymerization reactions with the acids and acrylates described above. Examples include: (1) Diacrylate and dimethacrylate esters of glycols, such as ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate and hexylene glycol dimethacrylate-1 to : (2) diacrylate and dimethacrylate esters of ethers or polyether glycols, such as diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene or tetraethylene glycol diacrylate and triethylene or tetraethylene glycol dimethacrylate; (3) polymerizability Allyl esters of unsaturated carboxylic acids, such as allyl acrylate, methallyl acrylate, allyl methacrylate, allyl acrylate, etharyl acrylate, methallyl methacrylate; (4) di- or trivinyl aromatic compounds, such as divinylbenzene and trivinylbenzene; 5) Di- or triallyl esters of dibasic and tribasic acids, such as diallyl phthalate, triallyl cyanurate, diallyl maleate, diallyl succinate, triallyl phosphate, diallyl oxalate, diallyl malonate, diallyl site (6) acrylate or methacrylate esters of polyols, such as di- or triacrylate or methacrylate esters of trimethylolethane, trimethylolpropane or pentaerythritol.

It is important to polymerize the monomers in specific proportions to obtain the desired polymer properties, but the exact proportions will vary depending on the desired polymer properties. The olefinically unsaturated carboxylic acid is used in an amount of about 15 to about 50 f2jt1%, particularly preferably about 20 to about 1%, based on the total fifl of the monomers used.
Approximately 40% m by weight is used. When m of the carboxylic acid used exceeds about 50% by weight, the resulting polymer salt becomes too hydrophilic and absorbs excessive amounts of water, resulting in (1) a soluble polymer, (2) a viscous solution or suspension and (3)
resulting in loss of macromolecular structural integrity. When the carboxylic acid coverage is less than about 15%, the resulting polymer salt is insufficiently hydrophilic and exhibits poor water absorption.

The alkyl acrylate is about 49.07 to about 82% by weight, particularly preferably about 59.0% by weight based on the total monomers used.
2-'-approximately 7 degrees D is used. When the a of the acrylate used exceeds about 82% by weight, the resulting salt-type polymer becomes insufficiently hydrophilic and exhibits poor water absorption. When the acrylate content is less than about 49.07%, the resulting polymer becomes too hydrophilic and absorbs excessive amounts of water (1
) resulting in soluble polymers, (2) viscous solutions or suspensions, and (3) loss of macromolecular structural integrity.

The matrix of crosslinking agents used is desirably limited to about 0.03% to about 3.0% by weight, preferably from about 0.08% to about 2.0%. This low crosslinker G was found to be sufficient to render the polymer salt water insoluble while retaining a high degree of water absorption. Use of less than 0.03% results in a polymer that acts as a thickener lacking individual particulate character as a neutralizing soil remover.

As the crosslinking agent 9 increases above 0.03%, the resulting polymer becomes increasingly discrete and rigid, minimizing swelling of the salt particles. When amounts of crosslinking agent greater than 3.0% are used, water absorption decreases to industrially unacceptable levels.

Suitable polymers include about 20 to about 40 weight percent olefinically unsaturated carboxylic acids selected from methacrylic acid and acrylic acid, and about 59,02 to about 78 weight percent methyl acrylate, ethyl acrylate, and n- an alkyl acrylate selected from methyl acrylate;
08 to about 2.0% by weight of a crosslinking agent as an essential component.

At the time of 1 go, (1) the gold component should be reacted as completely as possible. The polymers can be made batchwise, continuously or semi-continuously by conventional polymerization techniques such as solution, suspension or emulsion polymerization.

Suspension polymerization is preferred. Because this technology is 50-4
yields the acidic polymer product as a high surface area particle precipitate with an average particle size of 10-50μ
This is because it appears to be composed of deposits of smaller particles in the range. Most of these smaller particles appear as collapsed spherical high surface area donuts with 2-5μ protrusions on their surface.

The polymerization reaction is carried out in the presence of a catalyst. Play necessary for reaction! Catalysts forming groups are conventional and usually
These are organic peroxides, inorganic persulfates and free radical generating azo compounds. The catalyst is usually used in an amount of about 0.01 to about 2.0 parts by weight per 100 parts by weight of the total monochrome material to be reacted. Representative examples of organic peroxides include benzoyl peroxide, acetyl peroxide, bis(p-bromobenzoyl) peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, dicumyl peroxide, and cumene hydroperoxide. peroxide, bis(p-
methoxybenzoyl) peroxide, 2,2'-azobisisobutyronitrile, and the like. Examples of inorganic persulfates include ammonium, sodium and potassium persulfates. These can be used alone or in combination with sodium or potassium bisulfite. The polymerization is preferably carried out using a free radical catalyst,
It is also possible to use radiation polymerization, such as for example high-energy X-rays or gamma-rays.

Suitable commonly used surfactants and/or colloids can also be used during the polymerization reaction.

Polymerization times and temperatures can vary considerably depending on the monomer groups and catalysts used. Typically, the polymerization reaction will be completed within at least 30 minutes to several hours at a temperature of about 00 DEG to 100 DEG C., preferably 1 to 4 hours at 65 DEG to 90 DEG C. for maximum efficiency.

In a preferred embodiment, suspension polymerization is carried out as follows. The reactor is charged with deionized water and suspending agent and degassed with inert gas. The reactor can be heated as necessary to dissolve the suspending agent. A predetermined range of olefinically unsaturated carboxylic acids and fulkylacrylates are added either separately or as a mixture. Addition may occur at room temperature or at reaction temperature. The crosslinker and catalyst can be added to the monomer mixture simultaneously or separately.

The reactor contents are then agitated and heated by conventional means to initiate polymerization at a temperature about the lowest boiling point of the monomers. When polymerizing methyl acrylate, this temperature is approximately 70°C. The reaction is then continued to prevent completion of polymerization, after which the reactor contents are cooled. The polymer product can be recovered from the slurry by conventional filtration means or converted directly to its salt form in the slurry.

The final product slurry can be steamed at about 100° C. to remove any withdrawn unreacted monomers. Alternatively, a highly reactive redox catalyst can be added to give nearly 100% yield.

The slurry can then be filtered to recover the polymer in its non-swellable acid form, or the final slurry can be neutralized by adding a calculated amount of aqueous alkaline solution to convert the free acid groups to the salt form. . Alternatively, the filtered polymer cake can be redispersed in water and neutralized as described above, or dried, powdered and neutralized with alkali.

Typically, the solids in the final reaction mixture will be about 15% to
It is about 50%. Lower solids contents can be used, but are generally undesirable from an economic standpoint.

The resulting dry or slurry polymer product can then be stored or used directly in absorbent articles as is, for example by treating the substrate.

For example, an article where 1a'B= may be treated with an acidic polymer and then neutralized with an alkaline solution by conventional neutralization techniques to form a water-swellable polymer. Processing steps should be understood to mean complete particle dispersion or dispersion onto the substrate. The substrate to be treated can vary widely depending on the end use and can be, for example, wood pulp, cellulose fiber, paper, woven or non-woven fabrics, etc.

Any suitable organic or inorganic base can be used during neutralization. Representative compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, ammonia and sodium carbonate. Neutralization can be carried out by e.g. ethanolamine, jetanolamine, triethanolamine, methyl jetanolamine,
It can also be achieved with organic amines such as butylgetanolamine, diethylamine, dimethylamine, trimethylamine, triethylamine, tributylamine, etc. and mixtures thereof. The most preferred base is sodium hydroxide. In short, any basic material that does not adversely affect the polymer composition can be used.

In particular, what is critical in the neutralization reaction is to carry out complete and uniform reaction and neutralization using the minimum necessary amount of water. An effective matrix of water that can be used is a water ring to polymer ratio of about 4 to 10:1, preferably about 5 to 7:1.
It was found that the ratio was within the range of Using a ratio of less than 4:1, during neutralization all of the free water is rapidly absorbed by a small portion of the acidic polymer, leaving the remaining neutralizing agent to be transported to the unneutralized acidic polymer particles. There is a danger that very little water will remain. On the other hand, if the ratio exceeds 10:1, a large amount of absorbed water is unnecessarily removed during drying, resulting in no excessive energy consumption.

To achieve complete neutralization, a chemical Q theory must be observed between the equivalents of base dissolved in the alkaline neutralizing solution and the equivalents of carboxylic acid in the polymer slurry. However, at least one base, such as sodium hydroxide, should be used for every carvone containing the monomer moiety. However, as much as 20% excess of base can be used to ensure that all of the carvone iQI is neutralized by the neutralizing solution. In fact, only a slight excess is required to drive the reaction and achieve maximum swelling. Excess alkalinity is not harmful. Because,
This is because during drying, the acrylate ester moieties, particularly methyl acrylate, partially saponify and react to form additional sodium acrylate single n units in the polymer chain backbone.

Drying of polymer salts can be carried out, for example, by fluidized bed drying, rotary
A temperature sufficient to remove substantially all of the water associated with the polymer product without causing polymer degradation by conventional means such as kiln drying, shelf drying, vacuum drying and delta-bun drying. You can do what you want. Products containing up to 5% residual absorbed moisture are acceptable materials. Suitable drying temperatures are 25° to 150°C, particularly preferably 80°C.
The temperature can be 0 to 100°C.

Upon drying, the polymer salt particles aggregate to form a brittle mass of solid particles. This mass can be ground to form individual particles that are easier to handle and ship. Depending on the particular end use desired, particles from about 50 microns to about 2 meters are suitable for particles that absorb water rapidly and allow water to pass through the pre-swollen mass of particles to reach uncontacted material. It was found that it brings about It should be appreciated that as the particle size increases, the particle surface area to volume decreases, resulting in slower water absorption and ultimately more swollen particles. Similarly, when used in bulk, materials with smaller particle sizes tend to absorb water at a slower rate than larger particles as a result of reduced particle pore size and therefore reduced permeation rates. .

The polymeric products used in the present invention, due to their crosslinking properties and insolubility in solvents commonly used in molecular weight measurements,
The neutralized polymer is capable of absorbing many times its own weight of surrounding water. Thus, each individual absorbent particle has a It swells, or expands, to several times its individual diameter without destroying it.The absorption of phantom distilled water more than 100 times has also been observed at the mouth.In a 1% sodium chloride solution, the Up to a 30-fold increase occurred, while 15
Up to a 10-fold increase in weight Q was observed for ~25% sodium chloride solutions. This amount of absorption is particularly significant when it is observed that the polymer particles are substantially immobile therein and the resulting particulate material retains its structural integrity.

Water-insoluble and water-swellable polymers are preferably used in articles such as water-absorbent bandages that require water retention capacity.

When used in such applications, the polymeric material is preferably in solid granular form to provide maximum surface area for absorption and to ensure maximum surface area for absorption. At least about 1%, and preferably up to 90% by weight, of the polymer salt should be present in the composite absorbent article, based on the total weight of the article.

Depending on the type of absorbent article, the polymer salt can be dispersed in a support sheet or flexible support consisting of an absorbent layer of cloth fibers, wood pulp fibers, cotton linters, etc. or mixtures thereof. Absorbent layers of this type are used in the production of absorbent bandages and for example in surgical and dental sponges, menstrual tampons, diapers, meat trays, livestock beds I
- It can be any material commonly used in the manufacture of the above-mentioned articles of manufacture, such as filth mats, water separators (e.g., filter wicks), and the like. These materials consist of a support sheet or multiple layers of a support and an outer covering sheet (
all of which are well known in the art).

The water-absorbent article according to the present invention can be manufactured by incorporating the above-mentioned polymeric material into an absorbent bandage by conventional procedures,
This ensures that the desired particulate polymer is maintained in the most concentrated structure. In the case of menstrual tampons, this can be obtained by spreading the polymer particles as a layer over a layer of absorbent fibers and then winding this layer in the form of a roll with the polymer particles inward. . Steam treatment and drying of this composite will increase particle adhesion to the fibers. The resulting absorbent material will maintain its properties such as absorbing water. Other well known methods for making articles of this type are also considered to be within the scope of this invention.

The water-insoluble, water-swellable polymer used in the present invention can also be used as a soil conditioner to improve water retention and increase air capacity. Soil with a changed sand-silt-clay composition, especially when mixed with sand with high soil content,
Significantly improved water retention capacity is observed.

This higher water holding capacity is observed even at pressures of 1 to 15 par.

The use of polymer salts is clearly superior to untreated comparison soils, and the effect is particularly pronounced in sandy and more porous soils. This type of soil is characterized by the loss of excessive amounts of water both through evaporation and drainage;
Polymers strongly suppress this effect. A collateral effect of over-drainage in sandy soils is loss of nutrients through leaching. Polymers also inhibit this effect, so nutrients added to the soil are retained for a long time.

The remarkable water retention properties of these polymers make them particularly suitable for use in preventing damping-off of plants grown in sandy free v1 aqueous soils IR, such as those produced in arid regions of the earth. These polymers are beneficial in maintaining plant survival in the early stages and are particularly useful in lawns made of sandy or free-draining sandy soils, such as golf greens, land sports areas and footpaths. be. Also,
These can be used in nurseries, gardens, home gardens, or artificial soil.
Alternatively, it is useful for potted plants. The cost and need for regular irrigation and monitoring is significantly reduced. Therefore, they reduce the burden of water management by retaining more water in the plant beds and save labor by reducing the need for field irrigation or warm water irrigation. In general, they also improve land edges by increasing the water holding capacity of the soil;
Make it suitable for crop production. Finally, they are useful for loosening soils that have been compacted by natural or artificial processes, such as grassed or bare roads, fields or fragile lands. It is also useful during transplantation, where the water retention and close contact between the roots and water-swollen polymer particles reduces transplant shock and eliminates plant shock. Other uses of the present polymers is the seed coat, which provides a water-rich and drought-resistant environment for the early stages of germination and growth.

When used in solids, suitable polymeric materials are 65/35
10.1 is the sodium salt of EA/MAA/EGOMA. Although generally unequal to sodium salts in terms of water retention, potassium salts are advantageous in that they are not easily leached and provide nutrients that are available to plants over long periods of growth. This is based on the fact that potassium, as a counterion to the polymer, is released only slowly compared to the solubilization rate of typical soluble synthetic potassium-containing fertilizers. Therefore, potassium fertilization and water retention can be optimized by using a blend of both sodium and potassium polymer salts.

Honmei m Used in the heart, soil 3? j means any medium in which plants can grow and provides support, oxygen, water and nutrients. Examples of these materials include natural growth media and artificial or non-natural growth media such as glass peas, expanded organic materials (eg expanded polystyrene or polyurethane), calcined clay particles, ground plastic, and the like.

The invention will be further illustrated by the following examples, but the invention is not limited thereto. Parts and percentages shown are based on total weight unless otherwise stated.

In these examples, the following procedure was used to measure the absorbance of water and aqueous salt solutions. 100g of 190 polymer column
of 1% NaCl solution or 200 g of distilled water.

Let stand for 2 hours without stirring. Whatman Na
Use filter paper from step 4 until no more water flows through (
(usually 5 to 15 minutes). Weigh the swollen product, subtract the weight of the polymer, 19, and record the resulting swelling value. Absorption rate is determined by adding 1 g of polymer salt to 30 g of distilled water in a small jar. Gently mix the contents of the jar by shaking.

Observe and record the time required for the polymer to become completely solid, ie, the product no longer flows freely when the jar is inverted.

This example illustrates how to make the polymers of the invention by suitable suspension polymerization techniques.

In a polymerization reactor, 2000 g of deionized water and 3 g of Cellocize QP-4400 (a product of Union Carbide Co., hydroxyedyl cellulose powder with a 2% viscosity of 4.000 to 6.000 cps) as a suspending agent were added. ). The contents of the reactor were heated to 65"C to avoid dissolving the hydroxyedyl cellulose and then heated to 35"C.
[fJ] was cooled to °C.

Next, methyl acrylate 3 was added to the reactor while stirring.
A mixture of 25 g of ice methacrylic M1759, 0.5 g of ethylene glycol dimethacrylate as a crosslinking agent and 0.5 g of azobisisobutyronitrile as a catalyst was added. The contents of the reactor are transferred at a moderate flow rate (e.g. 1/min).
．． 0 OMI! ') was degassed by purging with nitrogen. The temperature was increased to 70°C and the mixture was allowed to polymerize for 3 hours. For the final time, the reactor temperature was increased to 80° C. to complete the reaction. Total reaction time was 3 hours.

The contents of the reactor were continuously stirred during the entire polymerization reaction.

After the reaction was completed, the reactor slurry was cooled to 25° C. and filtered through a vacuum filter. The filter cake is 1. It was oooog. To analyze the product and determine the yield, 115 parts of the filter cake were dried in a vacuum A-bun at 80°C for 16 hours, yielding an average of 40 mesh (
Approximately 34 to 36%
A granular acidic polymer containing methacrylic acid was prepared. The % conversion of monomer to polymer product was 97.0%.

The remainder of the filter cake is neutralized with a basic solution of sodium hydroxide, in which case each of the remaining 115 parts of cake is dispersed separately in 400 g of deionized water, and then 195 g of a 10% sodium hydroxide solution (e.g. This was done by rapidly and completely adding 20% excess of the theoretical amount required to neutralize the The resulting mass was dried in a vacuum oven at 80°C to remove the moisture content and then heated at 20°C.
The material was ground to a size that passed through a mesh sieve (US standard sieve size).

The brine absorption of this polymer salt was measured in a 1% thorium chloride solution. The filter cake was 243, which corresponded to an absorption of 23 times its own weight of water. In water absorption tests, water absorption of about 100 times the polymer weight was achieved.

Examples 2 to 17 Examples 2 to 17 show the preparation of methyl acrylate (MA) using the suspension technique of Example 1 at different ffl ratios at
and methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) as a crosslinking agent. The polymers of Examples 2-12 were neutralized by the method of Example 1, except that sodium hydroxide solution was used instead of lithium hydroxide solution. The procedure of Example 1 was used to neutralize the acidic polymers of Examples 13-17.

In Table 1, the absorption capacity of the alkaline polymer is expressed as a multiple of the dry form ω of the polymer. Absorption values were given for deionized water, 15% calcium chloride solution, and 15% sodium chloride solution. For convenience of calculation, the crosslinking agent shown indicates the ε of the substance added to the other two monomers used.

The above results clearly demonstrate that the polymer has high absorption capacity for water and aqueous salt solutions over a wide range of monomers and crosslinker concentrations. This data also shows that water absorption decreases as the crosslinker level increases. The resulting product, with a water absorption content of approximately 95%, consisted of hard, swollen particles that retained structural integrity with a dry feel.

At higher water absorption levels, the swollen particles were slightly soft but individually separated, and the non-agglomerated particles had a semi-dry feel.

Table T 15% 15% tJ HA )4AA EDMA Book CaC
l2NaCl28020 2 11 2 NT 38020 1 18 3.2 4.848020 0
．． 522 4.9 5.557525 1 18 4.
8 6.967030 1 17 5.5 6.376
040 1 16 4.8 NT88515 1 1
3 1.8 NT97525 0.528 5.8
6.9107525 0.337 6.1 8.611
7525 0.244 5.3 8.4127525
0.160 8.1 10.9137030 1 17
5.5 G, 3147030 0.531 6.2
7.8i57030 0.357 7.7 10.1
167030 0, j86 9.1 13.01770
30 0.05105 8.6 13.0AA =
Methyl acrylate MAA = methacrylic acid EDMA - ethylene glycol dimethacrylate NT - not tested Examples 18-24 Examples 18-24 illustrate the preparation of polymers according to the procedure of Example 1 using various monomers of different layering. ing. Example 18
．． Polymers 20 and 21 were neutralized by the method of Example 1 except that lithium hydroxide solution was used instead of sodium hydroxide solution. Examples 19 and 22-24 used the neutralization method of Example 1 with sodium hydroxide. Table 3 shows the amounts of polymer components used and the absorption test results.

For convenience, the amount of crosslinking agent shown indicates the order of the materials added to the other monomers used.

This result shows that acrylic acid gives approximately the same results as methacrylic acid in swelling in water. For swelling in the presence of high electrolyte concentrations, methacrylic acid is preferred. The results show that all polymers tested are sensitive to high S degrees of CaCl2 and NaCl, but the polymers still maintain high levels of absorption as well as retain structural integrity. . Example 24 also demonstrates the utility of a polymer in which some of the carboxylic acid monomers are replaced with other acid intermediates of Shobito.

Examples 25 and 26 Examples 25 and 26 used polymers made by the suspension polymerization technique of Example 1, using different weight ratios of monolayer and crosslinker. The acidic polymer was neutralized with a basic solution prepared from lithium hydroxide, sodium hydroxide, potassium hydroxide and triethanolamine. 1Jff used
One is methyl acrylate (MA), methacrylic I (M
AA)a and ethylene dimethacrylate (EDMA). Table 2 shows the monomers used and the results.

The amount of crosslinking agent represents the 1 added to the two other single materials used.

The results demonstrate the effectiveness of varying the neutralizing agent and therefore the resulting polymer salt product. The results also show that while the sodium and lithium polymers have substantially equivalent absorption for water, the libram compound gives better results in electrolyte solutions.

Although potassium polymers exhibit lower swelling efficiency, they have particular application in the agricultural sector due to their potential nutritional value. Triethanolamine salts have even lower absorption capacity, but may be particularly useful for cosmetic applications.

25 80 20 2 Li 11 3.
2Na 12.4 2 to 91.8 TEA 5 1.3 26 80 20 i Na 16 2
．． 3Li 18 3.2 Examples 27-40 This example demonstrates the effect of varying the ε of the assembly components to produce water-swellable and water-insoluble 11 polymers. The procedure of Example 1 was repeated to prepare the conjugate-sodium salt. The m of the monomers used and the results are shown in Table 2.

Mono-system (MA/MAA/EDMA') consisting of methyl acrylate, methacrylic acid and ethylene dimethacrylate
l was investigated over the MA range 50-80, the MAA range 20-50 and the EDMA range 0.03-0.3.

The results show that for each crosslinking level, maximum swelling at 1% Na C1 is obtained with polymers of about 35-40% MAΔ. The polymer particles that gave the swollen particles with high fS structural integrity had MAA concentrations ranging from about 20 to
It was found to be within the range of 40%.

Above 50% MAA and within the 0.3-0.03 crosslinker range, the structural integrity of the swollen particles was lost. Sugi escape maintenance ↑
1 degrades even with less than 0.03% crosslinker; therefore, the neutralized polymer in water exhibits indeterminate and non-filterable particles, which are distinguishable from conventional gelled viscous slurries or solutions. could not.

Table 1 Absorption rate of 1% Na Cl MAA EDMA Multiply of dry weight 2
780 20 0.3 52875
25 0.3 8.52965
35 0.3 8.730 50 5
0 0.3 8.73175, 25
0.1 173265 35 0
．． 1 20.53360 40 0.
1 203450 50 0.1
17.535 75 25 0.05
183670 30 0.05
2437 50 50 0.05 25
3880 20 0.03 1739
65 35 0.03 32.540'
50 50 0.03 26゜5M△
= Methyl acrylate MAA = Methacrylic acid ED MA = Ethylene glycol dimethacrylate'Examples 41-46 Examples 41-46 use methyl acrylate and methacrylic acid with varying amounts of different crosslinking agents and the suspension of Example 1 The polymer was produced by polymerization technology. The results are shown in Table 7.

This result shows that the polymers prepared with diethylene glycol dimethacrylate at 0.1% and 0.5% were 1% N
It is shown that they gave swelling ratios of 25 and 34 times in aCl, respectively. Therefore, the lower the level of crosslinking, the more readily hydrated and swellable polymer 19 is created. However, the lower limit is usually 0.03%.

This is because beyond this point the particle no longer swells to the equilibrium absorption level where the swollen particle maintains its structural integrity, but rather absorbs so much water that structural integrity is lost. In the latter case, the particles become extremely soft and
They coalesce, possibly even forming a viscous glue or polymer solution. When glycols higher than diethylene glycol dimethacrylate, such as tetraethylene glycol, are used as the dimethacrylate derivative, ! The hydrophilicity of the 1st position increased. Allyl methacrylate is an example of a crosslinking agent in which one vinyl group is present on the alkyl group of the acrylic ester and a second vinyl group is present on the carboxylic acid group, ie, M% methacrylate. Divinylbenzene is an example of a hydrocarbon crosslinker and does not contain hydrolyzable ester groups, so the resulting small aggregate is structurally stable with hydrolytically stable carbon-carbon bonds throughout its backbone and bridges. It has been completed.

1 plate - ] 2 and - 1% NaCI absorption example HA ) IAA X-binder dry type ♀
multiple of 41 65 35 0.1 diethylene
25 glycol dimethacrylate 42 65 35 0.05 diethylene 3
4 Glycol dimethacrylate 43 65 35 0.1 Trimethylol 2
3.510 Pantrimethacrylate 44 65 35 0.1 Allyl methacrylate 2
145 G5 35 0.2 Tetraethylene
18 Glycol Dimethacrylate 4G 65 35 0.1 Divinylbenzene
23-1Δ = Methyl acrylate M A A = Methacrylic acid Example 47 This example illustrates a method for producing polymers for use in the present invention and neutralizing polymer slurries in the presence of various surfactants. ing.

Into the polymerization reactor were added 20009 deionized water and 3 g of Cellocize QP-4400 as a suspending agent (a product of Union Carbide, a hydroxyethyl cellulose powder with a 2% viscosity of 40 oO to 6000 CpS).
filled with. The contents of the reactor were heated to 65°C to dissolve the hydroxyethylcellulose and then cooled to 35°C.

The reactor was then charged with methyl acrylate 3 while stirring.
Contains 25 g of ice methacrylic rli175, 1-0.5 g of ethylene glycol dimethacrylate as a crosslinking agent, and 0.59 g of azobisisobutyronitrile as a catalyst.
Added Turu Sawaimono. The contents of the reactor were then purged with nitrogen at a moderate flow rate (e.g., 100 IL/min) and the temperature was increased to 70°C.
The mixture was allowed to polymerize for 3 hours. During the final period, the reactor temperature was increased to 80°C to complete the reaction. Total reaction time was 3 hours. The contents of the reactor were continuously stirred during the entire polymerization reaction.

After completion of the reaction, the reactor slurry was cooled to 25°C. The slurry was diluted with 5009 water for better stirring and flow.

115 parts (600 g) of this slurry were transferred to a steel beaker and stirred very rapidly (3000 RPM) with a disperser. To this, 5% aerosol OT (
Dioctyl sodium sulfosuccinate (from American Cyanamid Company) was added. This suspension was then given 1
Upon addition of 95 g of 10% Na01-1, the slurry immediately solidified into a mass of soft, swollen, and brittle granules. The ratio of water to polymer in the neutralization step is 6.76 to 1.
Met. This brittle solid puttrium polymer salt was then dried in a vacuum oven at 80° C. to remove the water content.
It was then ground to a size that passed through a 20 mesh sieve (rice (1) standard sieve size). 1q of dry product absorbed 100 times its weight in water. In a 1% NaCl solution: 21 times its weight was absorbed.

The absorption rates were 8 seconds and 21 seconds, respectively.

Example 48 This example demonstrates the production of various absorbent articles using the polymers of the above examples.

0.5 g of the finely ground dry polymer salt from A0 Example 1 was slowly added to the decomposed cellulose slurry 2509 containing 5 g of cellulose. After mixing for 2 minutes, the slurry was diluted in the headbox of a conventional Nople & Wood Laboratory Sheet Machine, formed into a 12" x 12" hand-sealed shape, and dried to absorb water. Tested. This article contained 10% conjugate salt. This dry paper absorbed 12 times its weight in water.

86 The polymer suspension prepared according to Example 47 was diluted with 15% solids solution and neutralized with a 20 mole % excess of 10% NaσH solution. The neutralized polymer swelled and absorbed all the water, forming a hard, brittle paste. This was then diluted to 0.5% solids with water. This slurry 1009
was added to 250 g of a slurry of beaten cellulose pulp containing 59 cellulose. This was converted into a 12" x 12" handsheet and tested for water absorption, also as described above.

This dry paper absorbed 6.6 times its weight in water.

Six 4" x 10" pieces of paper towels weighing 3.5 g C0 were stacked one on top of the other, and 3.5 g of the finely ground polymer salt from Example 1 was evenly sprinkled over these sections. To the obtained multiplex pad,
Rime ice was rQ misted until lff1 increased to 2C1.

The wet pad was then dried at 80°C to fuse the layers. This pad is tightly rolled into an oval shape, 1
% NaCl solution for several minutes, then 1.5 p.
The degree of salt water absorption was measured by compressing for 5 minutes under si pressure. This pad absorbed 9 times more 1% Na Cl solution than the mold mouth. A similar comparative towel treated as described above without the polymer absorbed three times its weight in salt water solution.

Comparative Example A''G This example compared the water and aqueous salt solution absorption rates of various commercially available water-swellable and water-insoluble polymer products to the dry polymer salt prepared according to Example 1. The known chemical description and results are shown in Table 1. The results demonstrate that the polymer of the present invention is an unexpectedly excellent water-swellable and water-insoluble composition.

In this example, Comparative Substance A is identified on the market as Aqualon and is a product of Percules. Comparative material B is identified on the market as Viteller 1 and is a product of Union Carbide Company. Comparative material C is identified on the market as Viteller 2 and is a product of Union Carbide Company. The comparative material is identified on the market as Permatrubu 10 and is a product of National Starch and Chemical Company.

Comparative material E is identified on the market as Permatrubu 30 and is a product of National Starch and Chemical Company. Comparison ffF is commercially identified as H-Span and is a product of General Mills Chemicals.

This material is manufactured under license from the United States Department of Agriculture. Comparative material G is commercially identified as Dow Flake and is a product of the Dow Chemical Company and is disclosed in U.S. Patent No. 3.980,66.
No. 3 and No. 3,993.616.

Table ■ Absorption Multiple of Dry Mold Product Used in the Invention Water 1% NaC + Comparison WA 18 5 Internally Crosslinked Sodium Carboxymethyl Cellulose Fiber Comparison B 13 - Cross-P! Polyethylene oxide comparison substance C gelled body wash. Gel body wash.

Acrylamide-Na Acrylate copolymerization cannot be filtered. Not filtered.

Comparative 51D Gelled body wash. Gel body wash.

Acrylic ff with hydrophilic carboxylate! Unable to filter. Cannot be filtered.

Combined Comparative Substance E Acrylic having hydrophilic carboxylate group Cannot be filtered. 20.4m Combined Comparative Substance F Hydrolyzed Starch Polyacturamide Graft could not be passed. Unable to filter.

Comparative substance G Gelled body wash. Gel body wash.

Linear carboxylic acid polymer Electrolyte crosslinking salts cannot be filtered. I can't pass it.

The invention being thus described, it will be obvious that the same may be varied in many ways. It should be understood that these changes do not depart from the spirit and scope of the invention.

Claims (1)

[Scope of Claims] (1) A method for manufacturing a water-absorbing flexible article comprising a combination of a flexible sheet material and a dry-touch water-swellable and water-insoluble polymer salt powder, comprising: The polymer salt is produced by heating and stirring the monomer composition in water in the presence of a catalyst to polymerize the monomer composition, and after neutralizing it with a basic compound, the polymer salt is separated, dried, and ground to form a polymer salt powder. (a) 15-50% by weight of an olefinically unsaturated carboxylic acid; (b) 49.07-82% by weight of an alkyl acrylate (the alkyl group has 1-6 carbon atoms). ) and (c) a crosslinking agent consisting of a monomer having two or more polymerizable ethylene groups in an amount of 0.03 to 3.0% by weight. Method of manufacturing flexible article. (2) 20 to 40 as olefinically unsaturated carboxylic acid
A method for producing a flexible article for absorbing water according to claim 1, characterized in that % by weight of methacrylic acid or acrylic acid. (3) Claim 1, characterized in that it contains up to 8% by weight of itaconic acid, maleic acid or maleic anhydride based on the total amount of olefinically unsaturated carboxylic acids used.
A method for producing a flexible article for water absorption according to item 1 or 2. (4) 59.02-78% by weight of methyl acrylate;
The method for producing a flexible article for water absorption according to any one of claims 1 to 3, characterized in that the alkyl acrylate contains ethyl acrylate or n-butyl acrylate. (5) The method for producing a flexible article for water absorption according to any one of claims 1 to 4, characterized by containing 0.08 to 2% by weight of a crosslinking agent. (6) The crosslinking agent is diacrylate or dimethacrylate of glycol, diacrylate or dimethacrylate of monoether glycol, diacrylate or dimethacrylate of polyether glycol, allyl ester of polymerizable unsaturated carboxylic acid, di- or trivinyl aromatic A flexible material for water absorption according to claim 1 or 5 selected from the group of acrylates or methacrylates of compounds, dibasic or tribasic di- or triallyl esters, or polyols. Method of manufacturing the article. (7) The catalyst is selected from organic peroxides, inorganic persulfates, or free radical generating azo compounds, and the amount of catalyst used is from 0.01 to 2 parts by weight per 100 parts by weight of the total monomer composition. A method for producing a flexible article for water absorption according to item 1. (8) The method for producing a flexible article for water absorption according to claim 1, wherein a surfactant or colloid is further used in the polymerization reaction. (9) The basic compound for neutralization is an alkali metal hydroxide,
A method for producing a flexible article for water absorption according to claim 1, wherein the article is selected from alkali metal carbonates, ammonium hydroxide, ammonium carbonate, or organic amines. (10) The amount of water in the neutralization reaction is the total amount of water: the ratio of polymer is 4 to 1.
A method for manufacturing a flexible article for absorbing water according to claim 1, wherein the ratio is 0:1. (11) A method for producing a flexible article for water absorption according to claim 1, wherein the polymer is ground into particles of 50 μm to 2 mm. (12) The flexible sheet material is cloth fiber, wood pulp fiber,
A method for producing a flexible article for absorbing water according to claim 1, comprising cotton linters or a mixture thereof. (13) Claim 1, wherein the flexible article for absorbing water is a surgical or dental sponge, a menstrual tampon, a diaper, a meat tray, a mat for livestock pet waste, or a water separation device (for example, a filter wick). A method for producing a flexible article for water absorption as described in Section 1.