CA1312859C - Hydroxypropyl methyl cellulose ethers useful as thickening agents for organic liquids - Google Patents

Abstract

ABSTRACT

HYDROXYPROPYL METHYL CELLULOSE ETHERS USEFUL AS
THICKENING AGENTS FOR ORGANIC LIQUIDS

Hydroxypropyl cellulose ethers which have a methoxyl substitution of from 21 percent to 35 percent and a hydroxypropoxyl substitution of from 18 percent to 35 percent and a sum of the methoxyl and hydroxypropoxyl substitution of from 39 percent to 70 percent and which have a viscosity of at least 1000 mPa.s as a 2 weight percent aqueous solution are useful as thickening agents for organic liquids, optionally mixed with water. The hydroxypropyl methyl cellulose ethers having a methoxyl substitution of from 25 percent to 35 percent, a hydroxypropoxyl substitution of from 18 to 30 percent, and a number average molecular weight of at least 50,000 are novel compounds.

C-33,309-CA-div.

Description

~? ~ ~' HYDROXYPROPYL METHYL CELLULOSE ETHERS
USEFUL AS THICKENING AGENTS FOR
ORGANIC LIQUIDS
This is a divisional application, divided out of parent application serial No. 502,873 filed on February 27, 1986.
The invention concerns thickening agents of the hydroxypropyl methyl cellulose type, their use for thickening an organic liquid and new hydroxypropyl methyl cellulose ethers and their preparation.
Hydroxypropyl methyl cellulose ethers (HPMC ethers) have been known for a long time.
Various hydroxypropyl methyl cellulose ethers which are commercially available are those which have a methoxyl substitution of from 27 percent to 30 percent and a hydroxy-propoxyl substitution of from 4 percent to 7.5 percent; a methoxyl substitution of from 28 percent to 30 percent and a hydroxypropoxyl substitution of from 7 percentto 12 percent;
and a methoxyl substitution of from 19 percent to 24 percent and a hydroxypropoxyl substitution of from 4 percent to 12 percent. All these cellulose ethers can be used as primary suspending agents for the suspension polymerization of vinyl chloride. They are useful for controlling the size of the produced polyvinyl chloride polymer particles.

¦ From European Patent Application 0,080,580 it is known to use a hydroxypropyl methyl cellulose having a methoxyl substitution of 20 percent to 32 percent, a . J lo hydroxypropoxyl substitution of 2 percent to 10 percent and a viscosity of 30 to 70 mPa.s as a suspending agent for producing vinyl chloride (co~polymers which polymers are used for decreasing the viscosity of pasty i 15 polyvinyl chloride dispersions. Pastes of low viscosity ~re useful for producing articles which comprise a low ¦ amount of plasticizers.

From German Democratic Republic patent specification DD
160354, a process for producing polyvinyl chloride by ¦ suspension polymerization of vinyl chloride is known.
Combinations of oil-soluble fatty acid esters are used l as suspendin~ agents. It is-an object of said patent to -! 25 provide polyvinyl chloride which is able to absorb large amounts of plasticizer. However, it is not clear from the teaching what are the ranges of percentage of the methoxyl and hydroxypropoxyl substitution. The only hydroxypropyl methyl cellulose ether which the patent implies to have a relatively high me~hoxyl and ! hydroxypropoxyl substitution is stated to have a methoxyl degree of substitution of l.9S and a - hydroxypropyl molar substitution of 0.42.

:1 . - .
s,, ' 33~309A-Div.
l ' 3 ~ 3 ~

Some hydroxypropyl methyl cellulose ethers are commercially available which have a methoxyl substitution of from 16.5 percent to 20 percent and a hydroxypropoxyl substitution o~ from 23 percent to 32 ¦ 5 percent as well as hydroxypropyl methyl cellulose ethers which have a methoxyl substitution of from 19 percent to 28 percent and a hydroxypropoxyl 1 substitution of from 7.5 percent to 11.5 percent. These hydroxypropyl methyl cellulose ethers are known to be ¦ 10 useful in emulsion paints.

¦ From U.S. Patent 3,388,082 water soluble HPMC ethers are known which have a methoxyl degree of substitution ¦ 15 (DS) of from a.4 to 1.3, a hydroxypropyl molar substitution IMS) of from 0.2 to 1.4 and a total molar ¦ substitution of at least 1Ø The DS/MS values of 0.4/0.2; 0.4/1.4; 1.3/0.2 and 1.3/1.4 can be calculated as percent of methoxyl substitution/hydroxypropoxyl l 20 substitution. The corresponding weight percent values are 7 percent/8.3 percent; 408 percent/ 43 percent; 21 ¦ percent/ 7.8 percent and 15.2 percent/ 40.8 percent, respectively. ~PMC ethers which have a methoxyl substitution of from 27 percent to 30 percent and a ; hydroxypropoxyl substitution of from 4 percent to 7.5 percent, HPMC ethers which ~ave a me~hoxyl subs~itution ~-! . of from 28 percent to 30 percent and a hydroxypropoxyl substitution of from 7 percent to 12 percent~ and HPMC
¦ 3~ ethers which have a methoxyl substitution of from 19 percent to 24 percent and a hydroxypropoxyl ¦ substitution of from 4 percent to 12 percent and HPMC
ethers which have a methoxyl substitution of from 16.5 ¦ percent to ~0 percent and a hydroxypropoxyl substitution of from 23 percent to 30 percent are 1 33,309A-Div.

` " ~ 3 ~ ~ ~ ;d J

commercially available. These hydroxypropyl methyl cellulose ethers are well known as thickeners. While i these cellulose ethers are useful in aqueous systems, i unfortunately their use in organic liquids is limited because of their limited solubility in many organic solvents.

However, the thickening of organic liquids, optionally 1 containing water, is often desirable for a variety of : reasons such as to impart consistency ~e.g. to gel - alcohol fuel), to control rheology of and to provide -¦ adhesion to a substrate e.g. in paint remover formulations and to impart workability to non-agueous ¦ 15 mineral binder/filler systems(e.g~ gypsum ~andages).

¦ In U.S. Patent 3,617,588 a preparation of cellulose ether ~ilms, for example pharmaceutical capsule shells, is disclosed. The cellulose ethers are C2_4 hydroxyalkyl Cl_2-alkyl cellulose çthers which have a DS
I of 0.6 to 2.0 and a MS of 0.07 to 1~0 and which are 1 characterized by a viscosity of 2 to 20 mPa.s as a 2 `I weight percent aqueous solution at 200C. Specifically EPMC ethers are disclosed which have a DS of 1.8 to 2 and a MS of 0.15 to 0.35 which corresponds to a ¦ methoxyl substitution of 28 percent to 31 percent and a -hydroxypropoxyl substitution of 6 percent to 13 ¦ percent. U.S. patent 31493f407 discloses a process for preparing medical capsules from a solution of HPMC
ethers with a methoxyl content of 18 to 32 weight I percent and a hydroxypropyl cont nt of 4 to 15 weight percent and which is characteriæed by a viscosity of 2 ¦ to 20 mPa.s as a 2 weight percent aqueous solution at 20C. ~nfortunately, these ~P~C ethers are not very 33,309A-Div.

.

~L 3 ~ ~i r~ ~r~ 5 ~
'". S

useful as thickeners since a very large amount of HPMC
is required to obtain a substantial thickening effect.

In view of the deficiencies of the above mentioned HPMC
¦5 ethers which are presently known as thickening agents it is highly desirable to provide new HPMC thickening agents for organic liquids.
",', A useful thickening agent of the HPMC ether type for organic solvents is disclosed in U.S. Patent 3,839,319.
¦~he HPMC ethers have a DS of 0.2 to 1.0 and a MS of at least 1.5. The hydroxypropoxyl substitution of such HPMC ethers, expressed as weight percent, is more than 40 percent. Unfortunately, production on large scale has shown that the HPMC ethers of such a high hydroxypropoxyl substitution are difficult to be dried by application of heat since these HPMC ethers have ¦20 thermoplastic properties. Generally heat-dry;ng is however preferred. Accordingly it still remains highly ¦desirable to provide a further class of HPMC ethers which are useful for thickening organic liquids.
` '1 The present invention provides new thickening agents of the hydro~ypropyl methyl cellulose type for organic liquids. ~ process for preparing the new HPMC ethers is also disclosed.

I

., I

I 33,309A-Div.
1 .

, , .

6 ~ ~ ~ 2 ~ ~ ~
7~978-2D

From U. S. Patent 4,389,393 it is known to use hydroxy-propyl methyl cellulose ethers having a methoxyl substitution of 16-24 weight percent, a hydroxypropoxyl substitution of from 4-32 weight percent and an average molecular weight of at least 50,000 as a carrier base material which is useful in sustained release therapeutic compositions. However, it is not suggested to use these hydroxypropyl methyl cellulose ethers as thickening agents. In U. S. Patent 4,389,393 the above~mentioned commercially available hydroxypropyl methyl cellulose ethers are also discussed briefly. It is mentioned that the commercially available hydroxypropyl methyl cellulose ethers have a methoxyl content of from 16.5 to 30 weight percent and a hydroxypropoxyl content of from 4 to 32 weight percent but this statement is erroneous. The actual levels of substitution in commercial cellulose ethers have been noted above.
Some of the hydroxypropyl methyl cellulose ethers which are useful as thickening agents are novel. Accordingly, one aspect of the present invention are new hydroxypropyl methyl cellulose ethers which have a methoxyl substitution of from 25 percent to 35 percent, a hydroxypropoxyl substitution of from 18 percent to 30 percent and a number average molecular weight of at~

._ ~ ,. _ .
least 50,000 and a viscosity of at least 1,000 mPa.s as a 2 weight percent aqueous solution.
Another aspect of the invention concerns the use of a hydroxypropyl methyl cellulose ether for thickening an organic li~uid or a mixture thereof with water which ether has a methoxyl substitution of from 21 percent to 35 percent, a hydroxypropoxyl substitution of from 18 i ~ 7 , ., ¦ percent to 35 percent, a sum of the methoxyl and hydroxypropoxyl substitution of from 39 percent to 70 ¦ percent and which has a viscosity of at least 1,000 mPa.s as a 2 weight percent aqueous soll~tion at 20C.

A further aspect of the invention is a thickened ¦ organic liquid or a thickened mixture thereof with water which is characterized in that it contains a thickening amount of a hydroxypropyl methyl cellulose ether which has a methoxyl substitution of from 21 I percent to 35 percent, a hydroxypropoxyl substitution ¦ of from 18 percent to 3S percent and a sum of the methoxyl and hydroxypropoxyl substitution of from 39 ¦ 15 percent to 70 percent which ~PMC ether has a viscosity of at least 1000 mPa.s as a 2 weight percent aqueous ¦ solution at 20C.

¦ 20 Surprisingly, a considerable viscosity increase of many organic liquids, optionally mixed with water, can be ¦ obtained by the addition of the above mentioned EPMC
- ethers.
'~'1 .

; The hydroxypropyl methyl cellulose ethers ~PMC ethers) .. ¦ useful in this invention are prepared by me~hods known in the art. An example of one such process com~rises:
reacting cellulose with an aqueous alkali hydroxide, using 1 to 4, preferably 1.5 to 3.5, parts by weight of the aqueous alkali hydroxide per 1 part by weight of cellulose~ the alkali hydroxide having a I concentration of from 30 to 55 parts by weight, at a 's ' ~1 33,309A-Div.
.' I
!

. .

temperature of from 10 to 600C, preferably from 20 to 50C; followed by ¦ 2) reacting the product of step (1) above with methyl chloride and propylene oxide, using 0.3 to 0.9, ¦ 5 preferably 0.3 to 0.8, parts by weight of propylene oxide per l part by weight of cellulose, using 1 to 3, preferably 2.0 to 2.6, more preferably 2.1 to 2.4, I parts by weight of methyl chloride per 1 part by weight of cellulo~e, at a temperature of from 20 to lOO~C, ¦ 10 preferably 30 to 90C.
''I`
The reaction of step (1) can be carried out by any I conventional method, such as passing rolls of cellulose ¦ 15 through a bath or spraying aqueous alkali hydroxide on chopped cellulose.

The reaction of step (2) can have the methyl chloride ¦ 20 and propylene oxide added to the reaction either sequentially or simultaneously, e.g. either the whole ¦ amount of each reactant at one time (at one shot), or ~atch-wise (staged addition~.

During both steps (l) and (2) it is advantageous to ¦ control the air (oxygen) in the reaction vessel in order to control the molecular weight of the product.

Some of the literature available to describe HPMC ether I preparation is U.S. Patents 2,949,452; 3,388,082;
2,831,852; 4,410,693; and 4,456,751.

,1 ~ '`I ' ` 33,309~Div.

;, ~` 1 3 ~ 2 ~
g . .

The hyd~oxypropyl methyl cellulose ethers are defined by their methoxyl substitution, hydroxypropoxyl substitution and average molecular weight. The methoxyl and hydroxypropoxyl substitution have been measured and calculated according to ASTM-D 1347-72 and ASTM-D 2363-72, respectively. All the percentages of substitution are by weight of the finally substituted ¦ material.

1 10 The methoxyl subs~itution of the hydroxypropyl methyl I cellulose e~hers to be used as thickening agents, ¦ ranges from 21 percent, preferably from 22 percent, most preferably from 25 percent; to 35 percent, preferably to 33 percent, most preferably to 31 percent.

: ~he hydroxypropoxyl substitution of the hydroxypropyl methyl cellulose ethers to be used as thickening agents ranges from 18 percent; preferably from 20 percent; to ¦ 35 percent, preferably to 30 percent, most preferably to 27 percent.

The sum of the percentage of the methoxyl and -~¦ hydroxypropyl substitution is from 39 to 70 percent, preferably from 40 to 65 percent; most preferably from 44 to 58 percent.
i 30 ¦ The novel HPMC ethers have a methoxyl substitution of from 25 percent to 35 percent, preferably to 33 percent, most prefPrably to 31 percent and a 'I .
,; I
~ 33,309A-Div.

,, i , ~, . , lo ~3~
-hydroxypropoxyl substitution of from 18 percent to 30 percent, preferably from 20 percent to 27 percent.
I

The molecular weight of hydroxypropyl methyl cellulose ¦ 5 can be expressed as the viscosity of the solution thereof in a solvent therefor. ~nless otherwise ¦ stated, the molecular weight of hydroxypropyl methyl cellulose is given herein as the viscosity of a 2 weight percent solution of hydroxypropyl methyl cellulose in water as measured using an UBBELO~DE
I viscosimeter at 20C.

¦ The viscosities of 5, lO, lO0 and 400 mPa.s correspond to a number average molecular weight (Mn) of 10,000, ~ 13,000, 26,000 and 41,000, respectively~ The I viscosities of aqueous solutions of the HPMC ethers which are used as thickening agents according to the L 20 invention are at 20C at least l,000 mPa.s, preferably at least 151000 mPa.s. The viscosities of said ¦ solutions are generally up to 200,000 mPa.s, preferably to 150,000 mPa.s, more preferably to 120,000 mPa.s, most preferably to 75,000 mPa.s.
. .~
-l 25 ., .
-¦ The number average molecular weight (Mn~ can be : determined by osmotic pressure determinations. The ¦ number average molecular weight (Mn) of the novel ~PMC
ethers is at least 50,000. Preferably, it is from 55,000, more preferably from 120,000; to 2~0,000, more~
preferably to 250,000, most preferably to 220,000.

1 .
. .

. ,.
33,309A-Div.
I

r~ r~ r, ¦ By adding the above mentioned ~PMC ethers to an organic liquid or to mixtures thereof with water, thickened ¦ liquids of a wide range of desired viscosities can be obtained. The solubility of the ~PMC ethers depends on a variety of factors, e.g. on the level of substitution and on the average molecular weight of the HPMC ethers, on the polarity of the organic liquid and on the ¦ typets) and amount of functional groups of the organic liquid.

By an "organic liquid" an organic solvent or a mixture I of organic solvents is meant which are liquid at ambient pressure and ambient or slightly elevated 15 temperature, i.e. up to 500C.

In general~ at least one component of the organic liquid should comprise one or more heteroatoms if the L ~o organic liquid is not mixed with water. Preferred hbteroatoms are sulfur, nitrogen, oxygen or halogen, ¦ e.g., chlorine or bromine. Preferably, the organic ; liquid comprises one or more polar groups like for ` example-NH,-NH2,-C(O)-O-,-C(O)-N-,-COOH,-I=Oor-OH
;1' - .
Th~ most preferred organic liquids are aliphatic or cycloaliphatic al~ohols, e.g. methyl alcohol ~MeOH), I ethyl alcohol ~EtO~) (preferably technical grade), I isopropyl alcohol (e.g. comprising up to about lO
percent water), tertiary butanol, cyclohexanol, ; I dipropylene glycol methyl ether, 2-ethoxyethanol methoxyethanol and 2-butoxyethanol which are ~' 33,309A-Div.

:,.....

~3~J~

' commercially available as CELLOSOLVE, METHYLCELL050LVE, and BUTYLCELLOSOLVE~ respectively; aliphatic or cycloaliphatic ketones, e.g. acetone, methyl ethyl ketone or cyclohexanone; carboxylic acids, e.g. formic i acid, acetic acid or lactic acidi carboxylic acid S esters, e.g. methyl acetate and butyl acetate; one or more halogen atoms-containing solvents, e.g. methylene chloride, chloroform or ethylene chlorohydrin;
aliphatic and cycloaliphatic ethers, e.g.
cyclohexanone, tetrahydrofuran or dioxane; amines, e.g.
pyrrrolidone, N-methyl-2-pyrrolidon or morpholine;
¦;l amides, e.g. dimethyl formamide; and sulfur atoms-containing organic solvents, e.g. dimethyl sulfoxide.

The organic solvents generally comprise up to lO carbon ¦ atoms, preferably up to 6 carbon atoms.

¦ 20 Useful mixtures of organic liquids, optionally mixed with water, are for example mixtures of t-butanol/water, acetone/water, glycerin/water, methylene chloride/methanol and methylene chloride/ethanol.

~ The HPMC ethers described above can also be used for ¦~ thickening hydrocarbons if the hydrocarbons a~e mixed ~ with an organic solvent comprising at least one heteroatom. Pr~ferred examples of such mixtures are i 30 benzene/ethanol,-toluene/ethanol, naphtha/ ethanol and ~ylene/isopropyl alcohol.

I I

,.~, 33,309A-Div.

~ 3t~' . 13 The HPMC ethers described above are particularly useful for thickening polar organic liquids or mixtures thereof with water.

The term "thickened organic ~iquid or a thickened mixture thereof with water" as used herein means an organic liquid or a mixture of organic liquids, optionally mixed with water, which has been thickened I with a ~PMC ether described above.

After addition of the ~PMC ether, the organic liquid, optionally mixed with water, is generally in the form of a viscous, still pourable liquid or in the form of a highly viscous gel. The viscosity of the viscous liquid, gel or slurry is generally adjustable almost to ¦ any desired level by the appropriate selection of type, weight amount and molecular weight of the HPMC ether.
¦ 2~ For example, addition of a high molecular weight product may increase the viscosity of the organic jl liquid by over 100,000 mPa.s. As an example, an addition of 4 percent by weight of a ~PMC ether having an average molecular weight of about 220,000 to ethanol will result in a viscosity of about lS0,000 mPa.s.

Depending on its intended use, the viscosity of the viscous liquid or gel or slurry is generally from 100 mPa.s, preferably from l,000 mPa.s, most preferably I from S,000 mPa.s; to 180,000 mPa.s, preferably to ¦ 150,000 mPa.s. "Thickened" means that the viscosity increase of the organic liquid, optionally mixed with water, by the addition o the HPMC ether is at least lO
mPa.s, preferably at least S00 mPa.s, more preferably 33,309A-Div.
,;

... ..

I

at least 4000 mPa.s, most preferably at least 10,000 mPa.s. A "thickening amount" of a ~PMC ether is an amount sufficient to provide this viscosity increase.
The amount of HPMC ethers which is required to provide the desired viscosity increase depends on a variety of factors, e.g. on the molecular weight (i.e. on its viscosity as a 2 weight percent aqueous solution), on the methoxyl and the hydroxypropoxyl substitution of the HPMC ether and on the type of organic liquid.
Generally, from 0.05 percent to 10 percent, preferably from 0.1 percent to 5 percent by weight is added to the organic liquid or mixture thereof with water.

The hydroxypropyl methyl cellulose ethers used for the purpose of the present invention can be produced according to known methods, for example as described in U.S. Patents 2,949,452 and 3,388,082. The levels of substitution of the hydroxypropyl methyl cellulose 1 20 ethers of the present invention can be achieved by increasing the amounts of propylene oxide and methyl chloride and reaction times until the desired substitution level has been reached.
:;1 Examples 1 and 2 In Tables I to IV, the viscosities of different I thickened organic liquids, optionally mixed with water, 1 30 are shown. The ~gMC ethers of Examples 1 and 2 are thickening agents used for the purpose of ~he present invention whereas the HPMC ethers of Comparative Examples A to C are known thickening agents4 .
.,.
33,309A-Div.

~ b, ~

In all examples and comparative examples, the concentrations of the hydroxypropyl methyl cellulose ¦ ethers were 2 weight percent, based on the weight of the organic liquid. The viscosities were measured on a I BROOKFIELD RVT equipment at 200C, 20 minutes (Tables I
1 5 and II), and 24 hours ~Tables III and IV) after the I cellulose ether had been added to the solvent.

;~ In Tables I to IV, the methoxyl and hydroxypropoxyl substitution of the HPMC ethers are listed in column 1.
The viscosities of a 2 weight percent solution of the HPMC ethers in water as measured using an UBBELOHDE
viscosimeter at 20C are listed in column 2 of Tables I
¦ 15 to IV for characterising the molecular weights of the ~PMC ethers.

. ~0 -' , ' '1 ~1 ., .1 ' ",I
33,309A-Div.

, 16 ~ J ~

TABLE I
VISCOSITY (mP.s) after 20 minutes in 5 _ ~ _ __ .
(METHOXYU

PROPOXYL WATER 96 wt.% FORM DIOXANE PYRROLIDONE
-:; SUBSTiTUTlON) ,,.,......... __ _ __ __ __ __ : 1 10 _ __ __ . - ._ .: EXAMPLES __ __ __ _ _ ; 1 1 . (29/1 8~72000_ 3000 > 1 5000 1 3400 1 0000 2. (29/20)25000 1200 > 10000 . 5000 140 ~ ~ ~ __ . _ _ 15 ~ __ __ __ __ .
COMPARATIVE
. . ~ EXAMPLES
.. . _ _ . . . . ~ . _ _ __ . _ _ A ~18/28) 5000 10 10 20 1550 :"` . B. (29110) 4000 10 3850 20 60 ... = . _ . . ........ ..
C (2V08) 4000 10 11) 20 1200 ., ~ 20 l 1__ . ~' .. 2S

1' ~ .
. .

I

.~ :
,, 1.;, ' 1'' - 1:
:''.'I ' - 33, 309A-Div .
~ I
., ~

1 3 ~ 2 ~

;
!

TABLE I I
VISCOSITY lmPa.s) after 20 minutes in 5 ~ .
(METHOXYUPROPY- 2- CYCLO- DIPLENOEPY-.1 PROPOXYLWATFR LENE ETHOXY- I IEXA- GLYCOL
SLIBSTITUTION)GLYCOL ETHANOL NONE MEETTHHEYRL
,.1 10 __~ __ _~ . ____ ~ ___ __ __ ~
: EXAMPLES
. _ _ , ,,, __~ __ . ~
. 1. I29/19) 72000 60 675 . 10 20 2. (29/30) 25000 60 ~500 20 20 15 ~__ __ __ .
__ __ __ __ . ..
COMPARATIVE
EXAMPLES
_ __ __ ... .... .
A. ( 18/28~ 5000 60 10 10 10 . ~_ ._ . __ . . I
B. (29/10) a,ooo 60 10 14 10 . 20 ~ __ . . . _. ~ . . . _ I
C. (2V08) 4000 60 10 . ..... 10 .1 .

.; 25 ~! .
. .

I

', 1 33, 309A-Div .
1' TABLE III
VISCOSITY_LmPa.s) after 24 hours I

5~METI IOX`~L/ ___ __ __ -PROPOXYL 96 wt.% FORM PYRROLIDOI'JE
:: ~ SURSTITUTION) .____ __ __ _~8 __ .,__ __ ___ __ ~ _ .. 10 EXAMPLES __ . __ .
--1 1. (29/18) 72000 10600 >150000 29000 117~0 2. (29/20) 25000 6900 > 1 00000 .1 6000 1 S~
~ . -_, __ ~

EXAMPLES
__ __ __ .- . __ . . ~ ..
A. ( 18/28) 5000 10 10 10 1800 . . ~ __ . ... ,.. .. ._ . . . ~__ B. (29/10) 4000 10 14000 20 2S0 . . ~ ............ . _ _ __ . .
C. (2V08) 4000 10 20 10 1250 . 20 .___ __ __ ~_ .. .

,1 '1:
, 25 ':1 1,.

.1 ~1 33, 309A-Div.
I

1 3 ~
,. 1 1 9 TABLE IV
VISCOSITY (mPa.s) after_24 hours in I

5 ~ __ _ .

'.SU8STITUTION) GLYCOL ETHANOL NONE METHYL
. ~ ETHER
'1'' ____ __ ___ __ __ ... 1~ .
,~ . ~ . _ . ............. , . ~__ EXAMPLES
-.' ~____ _ , . . . , ... 1. (29/18~ 72000 60 7350 30 20 __ ___ _ __ _ .. -2. (29n0) 25000 70 ~3300 20 20 _ __ ~__ __ ~ ; . _ ___ . .
COMPARATIVE
EXAMPLES
. __ _ ..... . . . ..
~s A. (1~V28~ 5000 70 10 10 90 B. (29110) 4000 60 10 20 10 . . . _ _ . ~ . . ..
C. (2V08) 4000 70 10 20 10 ... _ .-... _ ~ -. ....... .

:'1 .r . .

~ .

~.' ~ , .
31, 309A-Div.

.

Tables I to IV show that in most of the tested organic liquids the ~PMC ethers used for the purpose of the present invention gave higher viscosities and were accordingly better thickeners than HPMC ethers which are known for aqueous systems. It is to be understood ¦ that the thickening effect of a given weight concentration of a HPMC ether in an organic liquid 1 depends also on the molecular weight of the HPMC ether.
i 10 The molecular weight of the ~PMC ethers is generally expressed as the viscosity of a 2 weight percent solution thereof in water. Furthermore, the viscosity of the organic liquid itself also varies. The j viscosity of ethanol (96 weight percent), chloroform, dioxane, 2~etho~yethanol, cyclohexanone, N-methyl-2-` pyrrolidone-and dipropylene glycol methyl ether is lO
mPa.s and the viscosity of propylene glycol is 60 I mPa.s, measured on a BROOKFIELD RVT equipment at 20C.
For taking the molecular weights of the HPMC ethers and the viscosities of the organic solvent into account for ¦ evaluating the thickening effects of the ~PMC ethers, the viscosity of the unthickened solvent is deducted ¦ from the measured values in Tables III and IV. The resulting values are expressed as percent of the 1 viscosity of the ~PMC ethers in water and are listed in ; Tables V and VI.

.

... .

33,309A-Div.
!

1 3 ~ ?~3 ~

TABLE V

VISCOSIT~ (mPa.s) after 24 hours (~ of aq.
viscosity after solvent viscosit~ has been deducted) 1- ~ _ _ _ .... . . . .
~METitOXYV
:: HYDROXY- ETHANOL CHLOP~O- N-METH`~L-2-; ¦ PROPOXYL WATER 96wt.% FORM DlOXANi- PYRROLIDONE
10 SU BSTiTUTlON) .
.,.. " ____ __ __ __ ____ .` ~ . . __.
: EXAMPLES
_ ~ __ __ . . ~ __ ... ... ~
1. (29/18~ 72000 15 >208 40 16 2. (29/20) 25000 28 >400 64 1 .. . _ ~ .... _.__ __ . .. __ ~, , .,, __ __ ._ COMPARATiVE
EXAMPLES
_~_ . . _ _ __ , A. (18/28) 5000 O O O 36 L. . 2 0 _ . __ ~- . . . _ B. (29/10) 4000 0 350 0 6 ~ __ ._ ~ ._ _ .
C. (2V08) 4000 0 0 0 31 .. ~ _ ..................... . . _ .
, . .

~, :- 1 .1 ~
. , ..

! 33,309A-Div.

TABLE VI
i I VISCOSITY (mPa.s) after 24 hours (~ of a~.
c ' viscosity after solvent viscosity__as been deducted) .. _ ~

f I 1 o HYDROXY- PROPY- 2- CYCLO- DIPROPY-. PROPOXYL WATER LENE ETHOXY- HEXA- GLYCOL
i SUBSTITUTION) GLYCOL ETHAI~IOL NONE METTHHEYL
___ ~_ a__ __ __ __ ! ' . ~__~ ___ __ ___ ~_ EXAMPLES
~ .__ __ _._ __ ~
I . - 1.(29l18) 72000 0 10 0 0;
2.(29nO) 25000 - 33 0 _ _ __ _. _ . ~ . - . ~ .
. __ . . . ~ =

EXAMPLES
... _ . . _, . . .
l A.(1~28) 5000 0 0 0 0 I I __ ~ . __ B. (291/10) 4000 O 0 0 O
.. __ ................ . .. __ ~__.
. C.(2~08) 4000 0 0 0 0 ., ~5 .;;~ .
., Although the thickening effect of the HPMC ethers of Examples 1 and 2 and of Comparative Examples A to C
il varied depending on the organic liquid, Tables V and VI
illustrate that the thickening properties of the HPMC
. ethers of Examples 1 and 2 are in most solvents , considerably better than of Comparative Examples A to C.
kll ...
1' 33,309A-Div.

' 23 1 3 ~ 2 ~,r~

In Table VII the viscosities of the different organic liquids are shown which were thickened with the HPMC
ether of Example 1 and of Comparative Example B which is a commercially available thickener for aqueous systems.

The ratio of the solvents in the mixtures are weight ratios. The concentrations of the HPMC ethers are listed as percent, based on the weight of the organic liquid. The viscosities are measured on a BROOKFIELD
RVT equipment at 200C, 24 hours after the HPMC ether has been added to the solvent.

33~309A-Div.

_, ~ 3 1~

.

~ TABLE VII
!

. ._ TRATION V~SCOSITY VISCOSITY
SOLVENT ETI IER (mPa.s~ COMP.
. ¦ .~, ~ (WEIGHT %)EX.1 EX. B
.. ~ __ __ ___ .: Methylene 1 11 100 10 Chloride .: 10 (MeCI~) __~ .
.: . MeCi2/EtOH 1 8200 10 . .- ~ . ~
MeClVEtOH 1 5300 i 250 (9416) _ __ ~ .
McCI2/EtOH 1 5100 2150 (94l6) . ~ ~ ~ . . ._ . '; .
ToluenelEtOH 1.7 6800 10 (100/20) .-. . , . . ..
I . . ToluenelEtOH 1.5 16200 10 2 (100/30) O
I

The comparison of Example 1 with the Comparative ~I` Example B illustrates that the ~PMC ethers used as - 25 thickening agents in the present invention can provade ~ considerably higher viscosities in mixtures of organic .~1............. solvents than known HPMC thickening agents.
The thickened organic liquids can be used for many applications, for.example as gelled alcohol fuel or as I palnt: removers and in the manufacturing of gypsum bandages.
Example 3 - Viscosities of different organic~ liquids thickened with an HPMC ether having a methoxyl/hydroxypropoxyl 33,309A-Div. .

I
~2 .1 25 :' substitution of 25% / 2s% and a viscosity of 150,000 as 2 weight percent aqueous solution are shown (in mPa.s) ¦in Table VIII. The viscosity in water was measured using an UBBELOHDE viscosimeter and the viscosity in ¦5 organic liquid was measured using BROOKFIELD RVT
equipment ~
¦ TABLE VIII
.- ~ . ~
-:1 10 __ __ ___ __ : . EtOH 2% 12,000 I MeOH 2~ 8,000 .. , . ~ ~ . - . . .. , . _ ~
MeC12 1 % 12,400 l MeOH/H2O 80/20 1% 2200 1 15 ~ _ .
. 60/40 1 % 3,400 , . ~ ~ ~ ~ ~
40/60 1% 4,500 . . ._ _._ ~
,~ 20/80 1 % 4,800 EtO H/H2O 80~2o ~ _ 3,000 .. 20 60/4~ 1 % 4,200 ~ . . ~ . ..
40/60 1% 5,000 20180 1% 5,300 MeC12/EtOH 98~2 ... . ..... 9,500 . . ... _ , .. ._ _ _ ~ _ .
; - 25 . 96/4 1% 6,100 . . ~ ................... ~ .....
.. ; . . 9~8 lo/o 5,300 ~ ... _ ~ ~ __ ~
. . ~16 1% S,000 ... ~ ~ ~ ~
. MeC12/MeOH 9B~ 1 % 6,500 ~ 96/4 1% 4,800 92/8 1% 4,300 ~16 1% 3,900 ,1 ~I 33,309A-Div.
'I .

1 3 ~

.

For illustrating how a HPMC ether useful for the ¦ purpose of the present invention can be prepared, reference is made to the following example which should ¦ 5 not be construed to limit the invention:

¦ Example 4 - Pre~aration of a HPMC ether 1 10 In a suitable sized reaction vessel equipped with l agitator, temperature controls and vacuum line, 2 sl kilograms (kg) of ground cellulose were alkalised with 6.3 kg of 50 weight percent aqueous sodium hydroxide at ¦ 15 about 300C.

The vessel was then evacuated and after evacuatlon, 4.6 kg methyl chloride and 1.2 kg propylene oxide were-added. The temperature in the vessel was subsequentlyincreased from 300C to 90oC~ After about 8 hours the ¦ HPMC ether was washed with water of about 90cC and recovered and dried.

2~
The resulting ~PMC ether had a methoxyl substitution of ?¦ 28 percent and a hydroxypropoxyl substitution of 21 percent. The viscosity of a 2 weight percent aqueous solution of the prepared ~PMC ether was 75000 mPa.s, measured using an UBBELOHDE viscometer.

.1 : .
~''1 33,309A-Div.
,.1

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for thickening an organic liquid or a mixture thereof with water which comprises adding a thickening amount of a hydroxypropyl methyl cellulose ether having a methoxyl substitution of from 21 percent to 35 percent, a hydroxypropoxyl substitution of from 18 percent to 35 percent and a sum of the methoxyl and hydroxypropoxyl substitution of from 39 percent to 70 percent and having a viscosity of at least 1000 mPa.s as a 2 weight percent aqueous solution at 20°C.
2. A method as claimed in Claim 1, wherein said ether has a sum of the methoxyl and hydroxypropoxyl substitution of from 40 percent to 65 percent.
3. A method as claimed in Claim 1, wherein said ether has a methoxyl substitution of from 22 percent to 33 percent and a hydroxypropoxyl substitution of from 20 percent to 30 percent.
4. A hydroxypropyl methyl cellulose ether having a methoxyl substitution of from 25 percent to 35 percent, a hydroxypropoxyl substitution of from 18 percent to 30 percent, a number average molecular weight of at least 50,000, and a viscosity of at least 1000 mPa.s as a 2 weight percent aqueous solution at 20°C.

5. A hydroxypropyl methyl cellulose ether as claimed in claim 4, wherein the methoxyl substitution is from 25 to 33 percent.

6. A hydroxypropyl methyl cellulose ether as claimed in claim 5, wherein the methoxyl substitution is from 25 to 31 percent.

7. A hydroxypropyl methyl cellulose ether as claimed in any one of claims 4 to 6, wherein the sum of the methoxyl and hydroxypropoxyl substitution is from 44 percent to 58 percent.

8. A hydroxypropyl methyl cellulose ether as claimed in any one of claims 4 to 5, wherein the ether has a number average molecular weight of from 55,000 to 280,000.

9. A hydroxypropyl methyl cellulose ether as claimed in claim 8, wherein the number average molecular weight is from 120,000 to 250,000.

10. A hydroxypropyl methyl cellulose ether as claimed in claim 4, wherein the ether has a number average molecular weight of from 55,000 to 280,000.

11. A hydroxypropyl methyl cellulose ether as claimed in claim 10, wherein the number average molecular weight is from 120,000 to 250,000.

12. A method as claimed in claim 1, wherein the hydroxypropyl methyl cellulose ether is as claimed in any one of claims 4 to 6.

13. A method as claimed in claim 1, wherein the hydroxypropyl methyl cellulose ether is as claimed in claim 4.

14. A method as claimed in any one of claims 1, 2 and 3, wherein said ether has a methoxyl and a hydroxypropoxyl substitution of at least 25 percent each.

15. A method as claimed in any one of claims 1, 2 and 3, wherein said ether has a viscosity of 1000 mPa.s to 200,000 mPa.s as a 2 weight percent aqueous solution.

16. A method as claimed in claim 15, wherein said ether has a viscosity of 15,000 mPa.s to 100,000 mPa.s as a 2 weight percent aqueous solution.

17. The method of claim 1, wherein the ether has a methoxyl substitution of from 24 percent to 28 percent, a hydroxypropoxyl substitution of from 23 percent to 27 percent, and a sum of the methoxyl and hydroxypropoxyl substitution of at least 49 percent, and has a viscosity of about 120,000 mPa.s to about 200,000 mPa.s in solution.

18. A thickened organic solvent containing one or more heteroatoms or a thickened mixture of an organic solvent with water, which organic solvent is liquid at ambient pressure and at a temperature of up to 50°C, containing a thickening amount of a hydroxypropyl methyl cellulose ether as defined in any one of claims 4 to 6 or 9 to 11.