AQUEOUS DISPERSIONS

Abstract

There is provided a method of making an aqueous dispersion wherein said dispersion comprises (A) one or more thickener and (B) solid particles of 1,2-benzisothiazolin-3-one, wherein said method comprises the steps of (a) forming an aqueous mixture (I) comprising water, a dissolved salt of 1,2-benzisothiazolin-3-one, and optionally one or more thickener, wherein the pH of said aqueous mixture (I) is 8.5 or higher, and (b) subsequently forming said aqueous dispersion by mixing together, in any order, components, wherein said components comprise an acid, said aqueous mixture (I), and optionally one or more thickener, wherein the pH of said dispersion is 1.5 to 7.5. Also provided is an aqueous dispersion made by that method.

Claims

1. A method of making an aqueous dispersion wherein said dispersion comprises (A) one or more thickener and (B) solid particles of 1,2-benzisothiazolin-3-one, wherein said method comprises the steps of (a) forming an aqueous mixture (I) comprising water, a dissolved salt of 1,2-benzisothiazolin-3-one, and optionally one or more thickener, wherein the pH of said aqueous mixture (I) is 8.5 or higher, (b) subsequently forming said aqueous dispersion by mixing together, in any order, components, wherein said components comprise an acid, said aqueous mixture (I), and optionally one or more thickener, wherein the pH of said dispersion is 1.5 to 7.5.

2. The method of claim 1, wherein said step (a) comprises the steps of (a1) forming a mixture (III) of water, 1,2-benzisothiazoli-3-one, and one or more thickener, wherein the pH of said mixture (III) is 7.5 or lower, and (a2) then raising the pH of said mixture (III) to 8.5 or higher.

3. The method of claim 1, wherein said step (b) comprises (b1) if aqueous mixture (I) does not already contain one or more thickener, making a mixture comprising said thickener and said aqueous mixture (I), and (b2) making a mixture comprising said acid and said aqueous mixture (I), wherein the amount of said acid is sufficient to bring said mixture comprising said acid and said aqueous mixture (I) to pH of 1.5 to 7.5, wherein said steps (b1) and (b2) may be performed in any order.

4. The method of claim 3, wherein said step (b1) is performed prior to said step (b2).

5. The method of claim 1, wherein the amount of said 1,2-benzisothiazolin-3-one is 1% to 40% by weight based on the weight of said aqueous dispersion.

6. The method of claim 1, wherein step (b) comprises the step of making a mixture comprising said acid and said thickener and the subsequent step of mixing aqueous mixture (I) with said mixture comprising said acid and said thickener.

Description

EXAMPLE 1: SOLUBILITY OF BIT IN NaOH SOLUTION

[0089] Protocol 1 was performed. The base solution was NaOH (50% by weight NaOH, based on the weight of the NaOH solution).

TABLE-US-00001 Batch No. 37a 37c 37d 37e 37g 37h 37i 37k BIT %.sup.(1) 5 10 12.5 15 20 25 30 40 Exotherm nd nd 27.9 nd 36.5 35.8 35.7 nd Peak (° C.) pH of 12.2 9.2 9.8 10.1 9.02 9.02 9.01 ne Mixture 1 Dissolution 23 23 27.9 <38 35.7 46 46 61 Temp. (° C.) Inherent −4.2 14.9 23.2 28.0 35.3 39.9 39.9 56.3 Precipitation Temp. (° C.) Note.sup.(1): % BIT by weight, based on the weight of the composition
As the batches of Example 1 show, using NaOH, the BIT concentration range is from 5% to 40% by weight of BIT based on the weight of aqueous mixture (I). It is contemplated that Example 1 supports the conclusion that the method of the present invention could be practiced using BIT concentrations of 5% to 40%, because, over that concentration range, it was possible to make aqueous mixture (I) at a temperature of approximately 60° C. or lower, and in each batch the dissolution temperature was higher than the inherent precipitation temperature. It is further contemplated that lower concentrations of BIT (e.g., 1% to 5%) could also be used.

EXAMPLE 2: SOLUBILITY OF BIT IN KOH SOLUTION

[0090] Protocol 1 was performed. The base solution was KOH (50% by weight KOH, based on the weight of the KOH solution).

TABLE-US-00002 Batch No. 38a 38c 38d 38e 38g 38h 38i 38k BIT %.sup.(1) 5 10 12.5 15 20 25 30 40 Exotherm 22.6 25.6 25.9 26.9 29.5 33.4 38.2 nd Peak (° C.) pH of 8.9 12.5 12.3 12.0 12.7 13.0 12.6 nd Mixture 1 Dissolution 23 23 23 23 29.5 48 45.2 68 Temp. (° C.) Inherent <−3 5 11 15 26 30 40 59 Precipitation Temp. (° C.) Note.sup.(1): % BIT by weight, based on the weight of the composition
As the batches of Example 2 show, using KOH, the BIT concentration range is from 5% to 40% by weight of BIT based on the weight of aqueous mixture (I). It is further contemplated that lower concentrations of BIT (e.g., 1% to 5%) could also be used.

EXAMPLE 3: SOLUBILITY OF BIT IN MONO-ETHANOLAMINE SOLUTION

[0091] Protocol 1 was performed. The base solution was mono-ethanolamine (pure).

TABLE-US-00003 Batch No. 39a BIT %.sup.(1) 5 Exotherm Peak (° C.) 24.8 pH of Mixture 1 9.1 Dissolution Temp. (° C.) 58.5 Inherent Precipitation Temp. (° C.) 62.5 Note.sup.(1): % BIT by weight, based on the weight of the composition
The batch in Example 3 shows that, using mono-ethanolamine, the BIT concentration range includes 5%. It is contemplated that, because the dissolution temperature of 5% BIT in mono-ethanolamine solution was above 60° C., higher concentrations of BIT would require dissolution temperatures well above 60° C.

EXAMPLE 4: SOLUBILITY OF BIT IN DIAMINOETHANE SOLUTION

[0092] Protocol 1 was performed. The base solution was diaminoethane (pure).

TABLE-US-00004 Batch No. 40a BIT %.sup.(1) 5 Exotherm Peak (° C.) 22.6 pH of Mixture 1 8.6 Dissolution Temp. (° C.) 70 Inherent Precipitation 56.6 Temp. (° C.) Note.sup.(1): % BIT by weight, based on the weight of the composition
The batch in Example 4 shows that, using diaminoethane, the BIT concentration range includes 5%. It is contemplated that, because the dissolution temperature of 5% BIT in diaminoethane solution was close to 60° C., higher concentrations of BIT would require dissolution temperatures well above 60° C.

EXAMPLE 5: SOLUBILITY OF BIT IN AMMONIA SOLUTION

[0093] Protocol 1 was performed. The base solution was ammonia (25% ammonia by weight in water, based on the weight of the base solution).

TABLE-US-00005 Batch No. 40a BIT %.sup.(1) 5 Exotherm Peak (° C.) 22.9 pH of Mixture 1 9.3 Dissolution Temp. (° C.) 63 Inherent Precipitation Temp. (° C.) 59.3 Note.sup.(1): % BIT by weight, based on the weight of the composition
The batch in Example 4 shows that, using ammonia, the BIT concentration range includes 5%. It is contemplated that, because the dissolution temperature of 5% BIT in ammonia solution was above 60° C., higher concentrations of BIT would require dissolution temperatures well above 60° C.

EXAMPLE 6: SOLUBILITY OF BIT IN LiOH SOLUTION

[0094] Protocol 1 was performed. The base solution was LiOH (pure solid).

TABLE-US-00006 Batch No. 42a 42c 42e 42g 42h 42i 42k BIT %.sup.(1) 5 10 15 20 25 30 40 Exotherm 23.7 26.0 28.9 31.8 35.9 38.5 nd Peak (° C.) pH of 11.6 11.4 11.3 11.5 11.4 11.4 nd Mixture 1 Dissolution 23 23 23 nd 36 47 >90 Temp. (° C.) Inherent nd −2.8 13. 19.8 >24.6 30.3 nd Precipitation Temp. (° C.) Note.sup.(1): % BIT by weight, based on the weight of the composition
As the batches of Example 6 show, using LiOH, the BIT concentration range is from 5% to 30% by weight of BIT based on the weight of aqueous mixture (I). It is further contemplated that lower concentrations of BIT (e.g., 1% to 5%) could also be used. It is contemplated that 40% BIT could be used if LiOH solution had been used instead of LiOH pure solid.

EXAMPLE 7: 5% BIT, NaOH, HCl, XANTHAN BEFORE ACID

[0095] Protocol 2 was followed. The amount of BIT was 5% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution).

TABLE-US-00007 Batch No. 43b 43c 43d 43e 43f.sup.(8) 43g.sup.(8) 43h 43i 43k Xanthan.sup.(2) 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 (%) TEG.sup.(2) 4 4 4.sup.(7) (%) dil. HCl 78 78 78 78.9 (g) conc. HCl 39 39 39 40.6 40.2 (g) HCl rate .sup.(3) 1.42 31.17 12.5 6.4 43.6 1.4 1.3 14.2 13.6 pH 6.4 6.5 5.7 4.9 4.8 4.9 7.3 6.7 6.7 viscosity 68 68 69 68 70 68 68 70 68 (KU) Sedi- 0 0 0 0 0 0 0 0 12 ment.sup.(4) PS 9.8 9.0 9.1 11.1 13.0 12.4 12.6 12.4 25.8 mean.sup.(5) D99.sup.(6) 30 23 23 30 30 36 36 30 71 Note.sup.(2): weight % based on the weight of the batch Note .sup.(3): acid addition rate in mole of acid per minute per kg of BIT Note.sup.(4): after centrifugation, weight % based on total BIT in centrifuge tube Note.sup.(5): Particle Size, weight-average diameter, micrometers. Note.sup.(6): Particle Size in micrometers, below which are 99% of all the solid particles of BIT. Note.sup.(7): also contained 0.5% Imbenlin C/91/025 (dispersant from Dr. Kolb Company), by weight based on the weight of the batch Note.sup.(8): Stirring at 185 rpm (all others at 600 rpm) Note.sup.(13): see Example 17 for definitions of “HCl2” and Batch 48e
Note (4): after centrifugation, weight % based on total BIT in centrifuge tube
Note (5): Particle Size, weight-average diameter, micrometers.
Note (6): Particle Size in micrometers, below which are 99% of all the solid particles of BIT.
Note (7): also contained 0.5% Imbentin C/91/025 (dispersant from Dr. Kolb Company), by weight based on the weight of the batch
Note (8): Stirring at 185 rpm (all others at 600 rpm)
Note (13): see Example 17 for definitions of “HCl2” and Batch 48e
All the dispersions made in Example 7 are acceptable. Batch numbers 43f and 43g show that slower agitation yielded somewhat larger particles. Batch number 43k showed that addition of Imbentin C/91/025 dispersant led to larger particles (it is contemplated that other dispersants may have different effects on the process). In these batches, thickener was added before acid, and in these batches, the speed of addition of acid does not have a large effect.

EXAMPLE 8: 5% BIT, NaOH, HCl, ACID BEFORE XANTHAN

[0096] Protocol 2 was used, except that acid was added before the Xanthan.

TABLE-US-00008 Batch No. 44b 44c 44d 44e 44f Xanthan.sup.(2) (%) 0.9 0.9 0.9 0.9 0.9 TEG.sup.(2) (%) 0 0 0 0 0 dil. HCl (g) 78 78 78 conc. HCl (g) 39 39 HCl rate.sup.(3) 1.4 31.2 14.15 1.5 6.4 pH 4.5 nd 6.3 4.1 4.7 viscosity (KU) 71 73 73 74 75 Sediment.sup.(4) 15 0 0 15 0 PS mean.sup.(5) 29.1 14.4 16.0 29.9 15.3 D99.sup.(6) 90 56 71 90 45 Notes.sup.(2)-.sup.(6): same as in Example 7
The batches with acid addition rate of less than 2 asu yielded dispersions with undesirable sediment and with D99 higher than desired. The other batches had no sediment, as desired, and had somewhat smaller particle size. That is, when acid was added prior to thickener, it was preferable to add the acid relatively quickly. The sample in which acid addition rate was 6.4 asu, the acid was also diluted prior to addition to aqueous mixture (I); it is contemplated that the combination of dilute acid and quick addition leads to low sediment and small particle size.

EXAMPLE 9: 20% BIT, NaOH, HCl, XANTHAN BEFORE ACID

[0097] Protocol 2 was followed, except that the batch size was 1 kg. The amount of BIT was 20% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution).

TABLE-US-00009 Batch No. 45a 45b 45c Xanthan.sup.(2) (%) 0.9 0.9 0.9 TEG.sup.(2) (%) 0 0 0 dil. HCl (g) 297 272 conc. HCl (g) 136 HCl rate.sup.(3) 0.35 0.35 10.6 pH 7.1 8.5 8.54 viscosity (KU) 90 93 100 Sediment.sup.(4) 0 0 0 PS mean.sup.(5) 17.3 15.2 14.7 D99.sup.(6) 56 45 45 Notes.sup.(2)-.sup.(6): same as in Example 7
The batches produced in Example 9 were acceptable, though the particles were larger than desired. The method of the present invention operates properly at BIT concentration of 20%.

EXAMPLE 10: 20% BIT, NaOH, HCl, ACID BEFORE XANTHAN

[0098] Protocol 2 was followed, except that the batch size was 1 kg, and the acid was added to form the aqueous dispersion before the thickener was added. The amount of BIT was 20% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution).

TABLE-US-00010 Batch No. 46a 46b 46c Xanthan.sup.(2) (%) 0.9 0.9 0.9 TEG.sup.(2) (%) 0 0 0 dil. HCl (g) 297 conc. HCl (g) 142 142 HCl rate.sup.(3) 0.38 3.26 11.4 pH 8.5 8.5 8.6 viscosity (KU) 92 99 101 Sediment.sup.(4) 35 0 0 PS mean.sup.(5) 49.3 33.4 28.0 D99.sup.(6) 140 90 90 Notes.sup.(2)-.sup.(6): same as in Example 7
Batches 46b and 46c were just acceptable dispersions, though the particles were larger than desired. Batch 46a (which used very slow rate of acid addition) had too large D99 and too much sediment to be acceptable. It is contemplated that the relatively high viscosity contributed to the stability (i.e., lack of sediment) in Batches 46b and 46c.

EXAMPLE 11: 5% BIT, NaOH, HCl, VARIED AMOUNT OF XANTHAN

[0099] Protocol 2 was followed. The amount of BIT was 5% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution).

TABLE-US-00011 Batch No. 47a 47b 48a 48b Xanthan.sup.(2) (%) 0.3 0.3 0.6 0.6 TEG.sup.(2) (%) dil. HCl (g) 78 78 conc. HCl (g) 39 39 HCl rate.sup.(3) 1.4 13.2 1.4 12.1 pH 7.2 7.4 7.0 7.2 viscosity (KU) 53 52 58 58 Sediment.sup.(4)(9) 13 13 0 0 PS mean.sup.(5) 12.9 11.2 10.6 9.7 D99.sup.(6) 36 30 30 30 Notes.sup.(2)-.sup.(6): same as in Example 7
All the batches in Example 11 had acceptable particle size. The samples with higher amount of Xanthan gum had no sediment, which is more desirable.

EXAMPLE 12: 5% BIT, NaOH, DIFFERENT ACIDS

[0100] Protocol 2 was followed. The amount of BIT was 5% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution). The acid was either acetic acid or formic acid.

TABLE-US-00012 Batch No. 49a 49b Xanthan.sup.(2) (%) 0.9 0.9 TEG.sup.(2) (%) 0 0 acetic acid (g) 19.1 formic acid (g) 17.2 acid rate.sup.(3) 0.92 1.07 pH 7.4 7.3 viscosity (KU) 70 69 Sediment.sup.(4)(9) 0 0 PS mean.sup.(5) 10.2 11.2 D99.sup.(6) 30 36 Note.sup.(2)-.sup.(6): same as in Example 7 Note.sup.(9): Centrifuge method: 3 × 5 mm at 1650 rcf
Both samples in Example 12 were acceptable, which shows that the method of the present invention may be practiced using organic acids.

EXAMPLE 13: 10% BIT, NaOH, HCl, XANTHAN BEFORE ACID

[0101] Protocol 2 was followed. The amount of BIT was 10% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution).

TABLE-US-00013 Batch No. 50a 50b Xanthan.sup.(2) (%) 0.9 0.9 TEG.sup.(2) (%) dil. HCl (g) 156 conc. HCl (g) 78 HCl rate.sup.(3) 1.4 13.9 pH 7.0 6.7 viscosity (KU) 75 76 Sediment.sup.(4)(9) 0 0 PS mean.sup.(5) 12.9 13.4 D99.sup.(6) 45 36 Note.sup.(2)-.sup.(6): same as in Example 7
Both samples in Example 13 were acceptable, which shows that the method of the present invention may be practiced using 10% BIT.

EXAMPLE 14: VARIABLE % BIT, KOH, HCl, XANTHAN BEFORE ACID

[0102] Protocol 2 was followed. The amount of BIT was 5% or 10% by weight, based on the weight of the batch. The basic solution was KOH (50% by weight KOH, based on the weight of the basic solution).

TABLE-US-00014 Batch No. 51a 51b 51c 51d BIT (%) 5 5 10 10 Xanthan.sup.(2) (%) 0.9 0.9 0.9 0.9 TEG.sup.(2) (%) dil. HCl (g) 84.7 156.8 conc. HCl (g) 39.5 78.6 HCl rate.sup.(3) 1.3 14.7 0.66 6.5 pH 7.0 6.9 7.2 7.1 viscosity (KU) 68 68 74 74 Sediment.sup.(4) 0 0 0 0 PS mean.sup.(5) 10.2 10.2 9.8 10.2 D99.sup.(6) 30 30 36 20 Note.sup.(2)-.sup.(6): same as in Example 7
Both samples in Example 14 were acceptable, which shows that the method of the present invention may be practiced using KOH. The two samples with slowest acid addition rate also used dilute acid, and the resulting dispersions were acceptable.

EXAMPLE 15: 5% BIT, LiOH, HCl, XANTHAN BEFORE PRECIPITATION

[0103] Protocol 2 was followed. The amount of BIT was 5% by weight, based on the weight of the batch. The basic solution was LiOH (added as a pure solid).

TABLE-US-00015 Batch No. 52a 52b Xanthan.sup.(2) (%) 0.9 0.9 TEG.sup.(2) (%) dil. HCl (g) 78 conc. HCl (g) 39.5 HCl rate.sup.(3) 1.3 11.9 pH 6.5 6.6 viscosity (KU) 67 70 Sediment.sup.(4)(9) 0 0 PS mean.sup.(5) 10.8 11.2 D99.sup.(6) 30 30 Note.sup.(2)-.sup.(6): same as in Example 7
Both samples in Example 15 were acceptable, which shows that the method of the present invention may be practiced using LiOH.

EXAMPLE 16: 5% BIT, NaOH, HCl, NON-XANTHAN THICKENER BEFORE ACID

[0104] Protocol 2 was followed. The amount of BIT was 5% by weight, based on the weight of the batch. The basic solution was NaOH (50% by weight NaOH, based on the weight of the basic solution). The Xanthan was replaced by Cellosize™ QP 52000H thickener (herein “HEC1”), which is a hydroxyethyl cellulose, a high molecular weight cellulosic polymer.

TABLE-US-00016 Batch No. 53a 53b 53c 53d 53e.sup.(10) 53f.sup.(11) HEC1.sup.(2) (%) 1 1 0.6 0.8 0.8 0.8 dil. HCl (g) 78.5 78.4 79.3 79.4 conc. HCl (g) 39.5 39.4 HCl rate.sup.(3) 1.2 14.7 13.4 1.3 1.3 1.3 pH 6.5 6.1 4.8 7.4 7.1 7.2 viscosity (KU) 89 90 56 68 70 78 Sediment.sup.(4)(9) 0 0 10 0 10 12 PS mean.sup.(5) 11.8 19.1 18.1 11.6 16.3 29.3 D99.sup.(6) 30 56 45 30 71 38.6 Note.sup.(2)-.sup.(6): same as in Example 7 Note.sup.(10): Also contained 4% triethylene glycol, by weight based on the weight of the aqueous dispersion. Note.sup.(11): also contains 0.25% by weight based on the weight of the batch of Imbentin C/91/025.
The batches in Example 16 were all acceptable, though the sediment and particle size were not as desirable in the sample with Imbentin C/91/025.

EXAMPLE 17: 5% BIT, NaOH, HCl, XANTHAN, ALTERNATIVE PROTOCOL

[0105] Batch size was 1 kg. Water was municipal tap water. NaOH 50% solution was 50% NaOH by weight, based on the weight of the NaOH solution. BIT paste and conc. HCl were the same as defined above in Protocols 1 and 2.

[0106] The following mixtures were made:

TABLE-US-00017 BIT20 65 pbw water, 24 pbw BIT paste, and 11 pbw NaOH 50% solution BIT10 82.6 pbw water, 12.0 pbw BIT paste, and 5.4 pbw NaOH 50% solution HCl2 5.59 pbw conc. HCl and 94.4 pbw water HCl3 from 8.6 pbw conc. HCl and 91.4 pbw water X/TEG 26.5 pbw Xanthan gum and 73.5 pbw triethylene glycol Both BIT20 and BIT10 were made at 50° C. and held at that temperature until use.

[0107] Batch 58a was made as follows. Premix58a was 3.4 pbw of X/TEG plus 71.6 pbw of HCl2. Then, 25 pbw of BIT20 was poured into a vessel containing 75 pbw of Premix58a, while the vessel was stirred as in Protocol 2 at 600 rpm. The pouring was performed by hand at a constant rate over 60 seconds.

[0108] Batch 58b was made as follows: Premix 58b was 3.40 pbw of X/TEG and 46.65 pbw of HCl3. Then, 49.95 pbw of BIT10 was poured into a vessel containing 50.05 pbw of Premix 58b, while the vessel was stirred as in Protocol 2 at 600 rpm. The pouring was performed by hand at a constant rate over 60 seconds.

[0109] Batch 58d was made as follows: 25.0 pbw of BIT20 was poured into a vessel containing 71.6 pbw of HCl2, while the vessel was stirred as in Protocol 2 at 600 rpm. The pouring was performed by hand at a constant rate over 60 seconds. Then 3.4 pbw of X/TEG was added to the vessel, as stirring continued.

[0110] Batch 58e was made as follows: Premix58e was 3.4 pbw of X/TEG plus 71.6 pbw of HCl2. Then, premix 58e was poured into a vessel containing 25 pbw of BIT20, while the vessel was stirred as in Protocol 2 at 600 rpm. The pouring was performed by hand at a constant rate over 60 seconds.

[0111] The resulting characteristics of each batch were as follows.

TABLE-US-00018 Batch No. 58a 58b 58d 58e pH 4.16 7.13 5.02 7.25 viscosity (KU) 66 68 71 75 Sediment.sup.(4) 0 10%.sup.(12) 0 10%.sup.(12) PS mean.sup.(5) 25.8 26.3 11.3 15.3 D99.sup.(6) 90 90 36 56 Notes.sup.(4)-.sup.(6) are the same as in Example 7. Note.sup.(12): sediment was not as firmly packed as sediment that is observed in other batches that show sediment. Stability is considered to be better than is usually associated with a result of 10%.
The batches in Example 17 all were acceptable, though the particles were larger than desired. Pouring concentrated solution of dissolved salt of BIT into diluted acid solution (as in batches 58a, 58b, and 58d) enables an acceptable dispersion in which the solid particles of BIT are acceptably small; particle size is even smaller when (as in batch 58d), thickener was not present during the precipitation step. The relatively low level of sediment (especially in Batches 58a and 58d) is desirable.

EXAMPLE 18: HIGH-I EXAMPLES

[0112] Various examples of aqueous mixture (I) were formed. The ingredients used were as follows: 640 g city water; 48 g BIT paste (concentration 84.8%); 2.24 g NaOH (concentration 50%); 7.20 g Xanthan gum. If these aqueous mixtures were to be used to make the aqueous dispersion of the present invention, acid would be added to the aqueous mixtures. Example 18-A could either be considered to be a low-I embodiment of aqueous mixture (I) followed by addition of Xanthan gum or considered to be a high-I embodiment of aqueous mixture (I) in which Xanthan gum was added after BIT and base. Examples 18-B, 18-C, 18-CR, and 18-D are high-I embodiments.

TABLE-US-00019 Example Example Example Example Example 18-A 18-B 18-C 18-CR 18-D Order of water, water, water, water, water, addition BIT, BIT, Xanthan, Xanthan, Xanthan, NaOH, Xanthan, BIT, BIT, NaOH, Xanthan NaOH NaOH NaOH BIT stirrer speed 500 rpm 500 rpm 500 rpm 750 rpm 500 rpm time to 110 min 60 min 80 min 50 min 45 to 90 complete min dissolution pH 9.52 9.18 11.97 11.95 9.85 appearance a few homo- homo- homo- homo- lumps geneous geneous geneous geneous sediment.sup.(13) 0.3 ml 0.2 ml 0 ml expect 0.sup.(15) 0.3 ml residue.sup.(14) moderate high almost none small none Note.sup.13: volume of sediment after centrifugation for 8 min at 45000 rcb. Note.sup.14: amount observed on stir shaft after dissolution Note.sup.15: It is expected that Example 18-CR would exhibit 0 ml of sediment after centrifugation, because Example 18-CR is the same as Example 18-C except for higher stirrer speed.
All five examples are useable for making the aqueous dispersion of the present invention. Examples 18-B, 18-C, 18-CR, and 18-D dissolved more quickly and had homogeneous appearance. Example 18-C and Example 18-CR had acceptable dissolution time, were homogeneous, and had the best level of sediment and residue. Example 18-CR also had desirably short dissolution time.

EXAMPLE 19: PH ADJUSTMENT

[0113] Further NaOH solution was added to Examples 18-A, 18-B, and 18-D. The final pH is shown below, along with the sediment (as assessed in Example 18).

TABLE-US-00020 Example 19-A Example 19-B Example 19-D starting material: Example 18-A Example 18-B Example 18-D final pH 12.09 11.08 11.97 sediment 0.1 to 0.2 ml 0 less than 0.1 ml
It is contemplated that raising the pH of Examples 18-A, 18-B, and 18-D decreased the sediment. It is further contemplated that if sufficient base were added to the mixture during the initial formation of aqueous mixture (I) so that the pH of the resulting aqueous mixture (I) were 11.0 or higher, that formulations analogous to Examples 18-A, 18-B, and 18-D would show reduced or eliminated sediment and/or residue. Additionally, it is also contemplated that if sufficient base were added to the mixture during the initial formation of aqueous mixture (I) so that the pH of the resulting aqueous mixture (I) were 11.0 or higher, that formulations analogous to Examples 18-A, 18-B, and 18-D would show reduced dissolution time.

EXAMPLE 20: FORMATION OF AQUEOUS DISPERSION

[0114] Example 18-CR was used to form an aqueous dispersion. HCl at concentration 30 to 34% (by weight based on the weight of the HCl solution) was added over 8 seconds at a rate of 57.4 mmol of acid per minute per kilogram of BIT. Final pH was 2.10. Viscosity was 73 KU. Particle size mean (assessed as in Example 7) was 11.34 micrometers. This aqueous dispersion was considered acceptable.