KR19990037129A - New Urethane Modified Nonionic Cellulose Useful As Thickener And Method For Making The Same - Google Patents

Abstract

The present invention is directed to reacting hydroxy functionalized cellulose with polyfunctional isocyanates to modify it to form cellulose derivatives having an extended expansion time in water. Hydroxyethyl (propyl) cellulose modified according to the present invention and suitably etherified carboxymethyl cellulose are particularly useful as thickeners because they have particularly advantageous rheological properties.

Description

New Urethane Modified Nonionic Cellulose Useful As Thickener And Method For Making The Same

The present invention relates to a novel class of modified nonionic water soluble polymers, in particular modified nonionic water soluble cellulose.

Known nonionic water soluble celluloses are useful for many industrial applications. They have been used, for example, as thickeners, as hydrous substances, as dispersants, in polymerization processes and in adhesives. In some of these applications, special types of cellulose are required. For other applications, various celluloses can be used.

The most commonly used modified celluloses are nonionic cellulose ethers and cellulose esters. Examples of such modified celluloses are methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose and cellulose acetobutyrate.

Denatured cellulose should be selected based on consideration of the thickening action of cellulose in water or a dilutable binder and dye. In general, the thickening action in water increases with increasing molecular weight. However, the preparation of high molecular weight cellulose is limited by the characteristics of the starting materials (eg cotton and other types of pulp). Cellulose that acts as a thickener must be hydrophobic because it can be expanded by water. Cellulose can be made hydrophobic, for example, by etherification. However, known methods of making cellulose hydrophobic often lower the molecular weight of cellulose as a result of the secondary reaction.

High molecular weight cellulose is difficult to process. Therefore, the polymerization reaction cannot be suitably performed in such a system because of the heterogeneous distribution of the high molecular weight cellulose material.

It is known in the art to convert low molecular weight cellulose into denatured cellulose which produces a high viscosity solution in water. These low molecular weight celluloses can be modified by polymerization, for example etherification with epoxides or chloroalkyl compounds. Modified cellulose ethers and / or esters of this type have high surface activity and can be used to prepare viscous aqueous solutions. The preparation of such ethers has been known since 1939 (US Pat. No. 2,160,783).

The main products of this polymerization reaction are hydroxyethyl or hydroxypropyl cellulose, which has high hydrophilicity and low water solubility. This low water solubility results in insufficient expansion capacity. This type of cellulose is difficult to industrially process to produce high viscosity solutions because cellulose is too fast in water and exhibits high heterogeneous dissolution and expansion forces.

The prior art teaches that these polymerization modified celluloses must be "hydrophobized" to prolong the expansion and dissolution times of the cellulose derivatives. Hydroxyfunctional cellulose was thus modified by adding short chain alkyl groups (eg, methyl, ethyl, propyl and butyl groups) and reacting with alkyl groups that are relatively long chain (C ₁₀ -C ₂₄ ). These techniques are described, for example, in US Pat. Nos. 3,091,524, 3,272,640, 3,435,027, and 4,228,277. The conversion rate (degree of substitution) in such processing is varied, and the resulting cellulose has overall different characteristics depending on the production method. The difference in rate and properties is also due to the degree of branching and the degree of polymerization of the cellulose chains. A review of cellulose used in the prior art to thicken a dilutable coating in water is described, for example, in Surf. Int. Coating (1995) 78 , pp 285-288.

In all nonionic water soluble celluloses used for this purpose, the water repellents were bound to the hydroxyfunctional cellulose ethers by etherification or esterification reactions.

Denatured celluloses containing carboxyl groups are also known. However, these modified celluloses are also modified by etherification or esterification. Such carboxycellulose can also be reacted with a base such as NaOH or an amine. The swelling action of the thus obtained ionic cellulose in water depends on the pH value (unlike the modified cellulose of the present invention).

It is not reported in the literature to modify the cellulose ethers by at least partially crosslinking the cellulose chains by any of the reactions described above.

It is an object of the present invention to provide modified nonionic water soluble celluloses which are not obtained by etherification or esterification.

It is another object of the present invention to provide partially precrosslinked cellulose.

A further object of the present invention is to provide at least partially crosslinked cellulose useful as thickeners, binders and coatings in aqueous solutions.

It is also an object of the present invention to provide aqueous solutions, binders and coatings thickened with cellulose of the present invention that are more stable than known systems made of modified cellulose that are not precrosslinked when exposed to shear forces.

It is a further object of the present invention to provide cellulose that is water soluble.

Another object of the present invention is to provide a method for producing a high viscosity solution in water.

It is a further object of the present invention to provide modified cellulose which is an effective thickener in aqueous formulations.

These and other objects, which will be apparent to those skilled in the art, are achieved by reacting hydroxyfunctional cellulose with polyfunctional isocyanates.

The present invention relates to nonionic water soluble celluloses comprising free hydroxy groups, methods of making such modified cellulose, and methods of making thickened aqueous systems from such modified cellulose.

The modified cellulose of the present invention is obtained by reacting hydroxy functional cellulose with polyfunctional isocyanates.

In the practice of the present invention, any water soluble cellulose, cellulose ether or cellulose ester comprising free OH groups can be used as starting material. Examples of such celluloses are hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose (DS <2.5), ethylhydroxyethyl cellulose and methylhydroxyethyl cellulose (DS <2.0). Carboxycelluloses such as carboxymethyl cellulose and carboxyethyl cellulose with DS <2.0 are also suitable.

Preferred types of cellulose are hydroxyethyl and hydroxypropyl cellulose having an average molecular weight of 50,000 to 500,000 daltons. Carboxymethylcellulose with DS <1.5, an average molecular weight of 20,000 to 500,000 daltons, and a degree of polymerization of about 70 to 2,000 units is also preferred.

Other preferred celluloses are water soluble hydroxyethyl and hydroxypropyl cellulose which give a viscous solution in water having a molecular weight of 20,000 to 500,000 daltons. Preference is also given to carboxymethyl and carboxyethyl cellulose which give rise to a viscous solution in water having a molecular weight of 20,000 to 500,000 daltons.

The polyfunctional isocyanates useful in the practice of the present invention may be of aliphatic or aromatic nature. Examples of these isocyanates are toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, methylenebis (phenyl isocyanate) and triisocyanatocyanurate. Particular preference is given to aliphatic diisocyanates such as 4,4'-methylenebis (cyclohexyl isocyanate) and 1,6-hexamethylene diisocyanate.

The process for producing the modified cellulose of the present invention is similar to the process known for reacting organic hydroxyfunctional compounds with isocyanates. One preferred method is to suspend hydroxyfunctional cellulose in a suitable organic solvent and then add the isocyanate to this suspension. The reaction can be carried out while heating (or) with the aid of a catalyst. The denatured cellulose produced by this reaction is then filtered off. Examples of suitable solvents are commercially available under the trade names Ketone (acetone, methyl isobutyl ketone), aromatic compounds (toluene, xylene), methylene chloride, chloroform, white oil and corresponding compounds of aliphatic compounds (e.g. isopar). Known inert organic solvents such as isoparaffinic materials available on the market) can include any. Preferred solvents for producing specially modified cellulose will depend on the type of cellulose and the isocyanate selected. In the practice of the present invention, the weight percent of the polyfunctional isocyanate used is no more than 10 weight percent of the modified cellulose. Preferred amounts of the polyfunctional isocyanate used in the practice of the present invention are 0.2 and 5% by weight isocyanate based on the amount of modified cellulose or the amount of modified hydroxy functional cellulose.

The present invention also provides a process for producing a thickened water containing system wherein the modified cellulose of the present invention is used as a rheological additive. The aqueous or predominantly aqueous systems in which the modified cellulose of the present invention has been found to be useful include emulsion paints, printing pastes and pigment pastes, dispersed fillers and dispersed pigments, paper additives, leather auxiliaries and textile auxiliaries, petroleum production formulations. , Detergents, adhesives, waxes, varnishes, pharmaceutical and veterinary formulations, agricultural pesticides, cosmetics, preferably shampoos and cleaning gels. Fresh water can also be thickened with the modified cellulose of the present invention. The thickening of fresh water may be desirable before incorporating other additives into the aqueous formulation or prior to incorporating modified cellulose.

The modified celluloses of the invention, and formulations comprising these modified celluloses, are suitable for thickening pure aqueous systems as well as thickening systems containing organic solvents or other volatile organic additives such as alcohols, glycols and ketones. Suitable. All systems that can be thickened according to the present invention may also include conventional auxiliary materials and additives such as antifoams, rheology and flow control agents, wetting agents, fillers and pigments.

Examples of systems which may be thickened according to the invention include aqueous dispersions of polyacrylates, aqueous or aqueous dispersions of mixed polymers of olefinically unsaturated monomers, aqueous dispersions of polyvinyl acetate, aqueous dispersions of polyesters, and corresponding binders of the binders. There are emulsions and ready-to-use formulations of dispersions of this type.

The advantage of using the modified cellulose of the present invention as compared to the profiles of systems enriched with other cellulose lies in the different rheological profiles of the systems thickened with them. In particular, the spraying tendency exhibited by varnishes and paints made with the modified cellulose of the present invention is markedly reduced, the delay of the dissolution process is increased and the aqueous expansion is promoted. The surface condition of the coating film prepared using the cellulose of the present invention as well as the flow and flow behavior are improved. In many cases, wetting of organic pigments (eg, tinting pastes) can also be improved.

Example

The present invention is explained in more detail by the following examples, whereby the present invention is not limited and all parts and percentages are by weight unless otherwise indicated.

Example 1 (Preparation of Compounds According to the Invention)

A. Modification of methylhydroxyethyl cellulose with low etherification. (Method 1)

25 ml of xylene (industrial mixture of isomers) in methyl hydroxyethyl cellulose (Walocel MW 20,000 GB, Wolff Walsrode AG) 15.0 in a 250 ml three necked round bottom flask with stirrer and reflux condenser added to g. This mixture was made into a suspension by stirring. This mixture was then added 1.5 g of a 10% by weight solution of Desmodur W (4,4'-methylenebis (cyclohexyl isocyanate)) (from Bayer AG) in xylene, and octa-solisen®, Octa 0.15 g of Solnigen Zinn 28 (Borchers GmbH) was added at room temperature. The reaction batch was then stirred at 50 ° C. for 1 hour. This denatured cellulose was then filtered off and dried at room temperature for 24 hours (“Cellulose 1A”).

B. Modification of Methylhydroxyethyl Cellulose (Method 2)

3.0 g of a 10% by weight solution of Desmodur® W. isocyanate (the same composition as in Example 1A), and Octa-Solizen® S, using the same apparatus as used in Example 1A. (Sn 28) (Same Composition as in Example 1A) 0.15 g was added to 15.0 g of methylhydroxyethyl cellulose, and the resulting mixture was stirred at 50 ° C. for 1 hour. This denatured cellulose was then filtered off and dried at room temperature for 24 hours (“Cellulose 1B”).

C. Modification of hydroxyethyl cellulose (method 1)

25 ml of xylene (industrial mixture of isomers) were added to methylhydroxyethyl cellulose (Natrosol® 250 H4BR) (Aqualon) in a 250 ml three necked round bottom flask (with stirrer and reflux condenser). East BV))). This mixture was made into a suspension by stirring. This mixture was then added to 1.5 g of a 10% by weight solution of desmodur W. isocyanate (the same composition as in Example 1A) in xylene (an industrial mixture of isomers), and Octa-Solizen® ES 28 (in 0.15 g) was added at room temperature. The reaction batch was then stirred at 50 ° C. for 1 hour. This denatured cellulose was then filtered off and dried at room temperature for 24 hours (“Cellulose 1C”).

D. Modification of hydroxyethyl cellulose (method 2)

3.0 g of a 10% by weight solution of Desmodur® W. isocyanate (same composition as Example 1A) in xylene (industrial mixture of isomers), and octa-solizen 0.15 g of Sn 28 (same composition as in Example 1A) was added to 15.0 g of Natrosol® 250 H4vial cellulose and stirred at 50 ° C. for 1 hour. The denatured cellulose was filtered off and dried at room temperature for 24 hours (“Cellulose 1D”).

Example 2.

A. Aqueous Solution Preparation

Each modified cellulose described in Example 1 was brought to a 2 wt% solution in water. 390.0 g of deionized water, 1 ml of Entschaeumer T (tri-n-butyl phosphate antifoam, Borchers GmbH), and 8.0 g of the corresponding cellulose were weighed and stirred in a 500 ml spiral stopper glass vessel. Then 2.0 g of concentrated ammonia water was added and the resulting mixture was stirred. The entire batch was then placed on the flask roller (1 revolutions per second). Finally the batch was left at room temperature for 24 hours.

B. Inflation Time

The method used to measure the expansion time for each of the modified celluloses prepared in Example 1 was as follows. 40 g of cellulose were incorporated into 196.0 g of deionized water in a 500 ml beaker and the mixture was slowly stirred with a glass rod. The elapsed time before the cellulose powder particles remained in the suspension was measured. The delay of the dissolution process (“expansion time) measured for each of the modified celluloses prepared in Example 1 is shown in Table 1 below.

Consequences of Melting Process Retard Cellulose Inflation time Wallo's m double oil 20000 zobi (unchanged) 40 minutes Cellulose 1A 50 minutes Cellulose 1B 55 minutes Natrosol 250 H4 Vials 20 minutes Cellulose 1C 35 minutes Cellulose 1D 45 minutes

C. Viscosity Measurement

The viscosity of each of the solutions prepared in Example 2A was measured at 2.55 s ⁻¹ and 600 s ⁻¹ at 23.0 ° C. using a Haake VT 550. The results are shown in Table 2.

Viscosity of 2% Aqueous Cellulose Solution Cellulose Viscosity of 2 wt% solution 2.55 s ^-1 600 s ^-1 Wallo's m double oil 20000 zobi (unchanged) 15000 mPas 170 mPas Cellulose 1A 23500 mPas 175 mPas Cellulose 1B 21000 mPas 170 mPas Natrosol 250 H4 Vials 21000 mPas 70 mPas Cellulose 1C 16500 mPas 80 mPas Cellulose 1D 17500 mPas 80 mPas

Example 3 Preparation of Internal Emulsion Paint Containing Modified Cellulose

A. Internal emulsion paints comprising (denatured) methylhydroxyethyl cellulose with a low degree of etherification.

Internal emulsion paints were prepared according to the following formula.

268.0 g deionized water

2.0 g Calgon N New (10% polyphosphate solution in water, from BASF AG)

1.0 g Novco 8034 (mineral oil antifoam; Henkel HgaA)

6.0 g cellulose 1A or 1B

1.0 g concentrated ammonia water

5.0 g Dispex GA 40 (dispersant; product of Allied Colloids)

5.0 g Dowanol DPnB (dipropylene glycol n-butyl ether; from Dow Chemical Corp.)

2.0 g Preventol D6 (preservative; manufactured by Bayer AG)

57.0 g Kronos 2310 Titanium Dioxide (from Kronos Titan AG)

80.0 g Socal P2 (synthetic calcium carbonate; manufactured by Solvay AG)

91.0 g Fintaltalk M30SL (Talc; Finntalk)

125.0 g Omyalite 90 (Chalk; from Omya GmbH)

297.0 g Omyacarb 5 GU (analysis; Omya GmbH)

The mixture was dispersed for 15 minutes in the dissolver. 60.0 g of Freyhoff styrene acrylate dispersion Cady 524 U (KD 524 U) were then added and the mixture was homogenized in the dissolver for 3 minutes.

Technical application data were obtained for emulsion paints made with modified cellulose 1A and modified cellulose 1B and are shown in Table 3.

Cellulose Viscosity at 10.3 s ^-1 [mPas] Viscosity at 600 s ⁻¹ [mPa · s] Spray Tendency ^* Pigment Wetting ^** Wallocell M.U.20000 Gibi (unchanged) 12,000 120 4 2 Cellulose 1A 15,000 120 2- One Cellulose 1B 14,500 120 2- One ^* Spraying trend: Test method described below ^** Pigment wetting: Test method described below

B. Preparation of Internal Emulsion Paint Containing Hydroxyethyl Cellulose

Internal emulsion paints were prepared according to the following formula.

270.0 g deionized water

2.0 g calgonn nu (10% polyphosphate solution in water, from BASF AG)

1.0 g of Novo 8034 (mineral oil antifoam; Henkel HGaA)

4.0 g cellulose 1C or 1D

1.0 g concentrated ammonia water

5.0 g dpex GE 40 (dispersant; product of Allied Colloids)

5.0 g Towanol Difienbi (dipropylene glycol n-butyl ether; from Dow Chemical Corp.)

2.0 g Preventol Di6 (preservative; from Bayer AG)

57.0 g Kronos 2310 Titanium Dioxide (from Kronos Titan AG)

80.0 g Sokal P2 (synthetic calcium carbonate; manufactured by Solvay AG)

91.0 g Pintalc M30 SL (Talc; Finntalk)

125.0 g Oomialit 90 (Chalk; from Omya GmbH)

297.0 g Omicarb 5 fat milk (analysis; Omya GmbH)

The mixture was dispersed for 15 minutes in the dissolver. 60.0 g of Freihof styrene acrylate dispersion Cady 524 oil was then added and the mixture was homogenized in the dissolver for 3 minutes.

Technical application data for this paint were obtained and shown in Table 4.

Technical application data for interior emulsion paints Cellulose Viscosity at 10.3 s ^-1 [mPas] Viscosity at 600 s ⁻¹ [mPa · s] Spray Tendency ^* Pigment Wetting ^** Natrosol 250 H4 Vials 2440 200 4 2 Cellulose 1C 2700 490 2- 2 Cellulose 1D 2900 490 2- 2 ^* Spraying trend: Test method described below ^** Pigment wetting: Test method described below

Test Method for Measuring Spray Tendency of Emulsion Paints

Device used for testing:

Top-pan Scales

stopwatch

Fleece roller 11 cm wide by 2.5 cm in diameter with roller holder

Paint Tray with Rubbing Area

11 cm x 12 cm etherit tile on a 20 cm x 30 cm cut lenetta membrane

Large Renetta film of 30 cm × 43 cm

Reagents: No other reagents are needed.

process:

The clean fleece roller was first moisturized and rotated on a dry hand towel to ensure that all measurements were made under the same conditions. 50-60 g of the emulsion paint to be tested were weighed in a paint tray. The balance was then zeroed and 30 g +/- 0.1 g of emulsion paint was weighed on a fleece roller. Care must be taken to ensure that the paint works perfectly on the rollers. The ethernit tile was positioned in the center of the large Renetta film along with the Renetta film in such a way that the paint splash could only contact the upper and lower portions of the large Renete film. The roller was then rotated back and forth in 30 regular intervals over an ethernit tile in 30 seconds. During this rotation, the roller must be rotated straight up to the upper and lower ends of the ether knit tile without slipping the ether knit tile. The paint splash was then dried for 5 minutes. For further testing, the ethernit tile should be precleaned with tissue so that the paint remaining on the ethernit tile does not affect other evaluations.

evaluation:

The amount and size of the paint splash was measured. The grades given were:

1: only independent splash

2: slight little splash

3: many small splashes or very few big splashes

4: many small splashes (three or more) or some large splash

5: many small splash and big splash

6: very many big splash

Test history for measuring the distribution of pigments in emulsion paints ("pigment wetting")

Device used for testing:

Top-Pan Scales

297 mm × 210 mm leneta membrane

100 μm coated knife

180 ml polyethylene beaker

reagent:

Luconyl Violet 5894 (made by BASF)

Deionized water

process:

A 1:10 dilution solution of ruconyl violet in deionized water was prepared.

99.5 g of the emulsion paint to be tested were weighed in a polyethylene beaker on a top-pane scale. Then 5 g of ruconyl violet 5894 was previously added thereto. The whole mixture was then thoroughly stirred by hand. Luconyl violet should be uniformly distributed.

The batch was left in air for 10 minutes, stirred carefully again, and then applied longitudinally onto the Lanetta membrane using a 100 μm coating knife.

After 2 minutes, in a small area covered with paint, the circle was carefully pulled out for 5 seconds with the index finger while keeping it from erasing. After this process, the Leneta film must not be visible through the paint coating. This process was repeated three times every two minutes at the new paint application point. The membrane was then thoroughly dried for 1 hour.

evaluation:

The color difference between the rubbed and non-contact surfaces was evaluated.

Criteria: The greater the color difference, the poorer the distribution of the pigment. (Pigment Dispersion Liquid) The color distribution is so early that the pigment distribution is not good. (Unfavorable pigment stability)

While the invention has been described in detail above for purposes of illustration, it will be understood that such details are for the purpose of illustration and that changes may be made by those skilled in the art without departing from the spirit and scope of the invention. .

The present invention provides a thickener composition which not only has advantageous rheological properties but also improves the surface state of the coating film and the wetting of the organic pigment.

Claims (11)

Nonionic systems comprising free OH groups, produced by reacting at least one water soluble cellulose, cellulose ether or cellulose ester comprising free OH groups with from about 0.2 to about 10.0 weight percent polyfunctional isocyanate based on the weight of cellulose Water soluble modified cellulose. The nonionic water soluble cellulose of claim 1 wherein from about 0.2 to about 5.0 weight percent of the polyfunctional isocyanate is used based on the weight of the cellulose. The process for producing cellulose of claim 1 wherein the hydroxy group containing cellulose is reacted with from about 0.2 to about 10 weight percent of the polyfunctional isocyanate based on the weight of the cellulose. The process of claim 3 wherein the reaction is carried out in the presence of an inert organic solvent. The method of claim 4, wherein the reaction mixture comprises a catalyst that catalyzes the reaction between isocyanate and hydroxy groups. The method of claim 3, wherein the reaction mixture comprises a catalyst that catalyzes the reaction between isocyanate and hydroxy groups. The process of claim 3 wherein the reaction is carried out at elevated temperature. The process of claim 3 wherein the reaction is carried out at a temperature of about 40 to about 100 ° C. The method of claim 1, wherein the cellulose reacting with the polyfunctional isocyanate is from the group consisting of methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, hydroxyethylmethyl cellulose and hydroxypropylmethyl cellulose. Which method is chosen. A method of making a highly viscous aqueous system, comprising adding the modified cellulose of claim 1 to the aqueous system. 11. The aqueous system of claim 10, wherein the aqueous system is an aqueous industrial coating, a water-soluble industrial coating, gypsum, paint, printing ink, textile dyes, colored printing pastes, pharmaceutical formulations, cosmetic formulations, detergents, adhesives, waxes and varnishes. And selected from the group consisting of: