CA2016096A1

CA2016096A1 - Liquid surfactant polymers of tetrahydrofuran and ethylene oxide

Info

Publication number: CA2016096A1
Application number: CA002016096A
Authority: CA
Inventors: James H. Merrifield; Mohamed M. Hashem; Robert B. Login
Original assignee: GAF Chemicals Corp
Current assignee: GAF Chemicals Corp; Rhone Poulenc Surfactants and Specialties LP
Priority date: 1989-05-26
Filing date: 1990-05-04
Publication date: 1990-11-26
Also published as: IL94498A0; AU5810990A; WO1990014327A1; ZA903257B

Abstract

LIQUID SURFACTANT POLYMERS OF
TETRAHYDROFURAN AND ETHYLENE OXIDE
Abstract Liquid surfactant polymer products of tetrahydrofuran and ethylene oxide, and process for making the same, are provided herein. The polymers comprise a hydrophobic central segment, transition copolymer segments extending outwardly from the central segment characterized by a continuously increasing EO mer unit content relative to the THF mer units therein, and hydrophilic termini segments of substantially EO mer units.

Description

5~
LIQUID SURFACTANT PO~YMERS OF
TETRAHYDROFURAN AND ETHYLENE OXIDE

BACKGRO~ND OF THE INVENTION

1. Field of the Invention This invention relates to copolymers of tetrahydrofuran (THF) and ethylene oxide (EO), and, more particularly, to liquid surfactant polymers of THF and EO
having a wide range of molecular weight and monomer content.

2. Description of the Prior Art Surfactants based upon copolymers of THF and EO
are disclosed as alternatives to nonionic surfactants.
Block copolymers of these monomers have a well-defined hydrophilic and hydrophobic structure and exhibit useful surface active properties. Unfortunately, block copolymers are pastes or solids at ambient temperatures which makes them very difficult to handle.
Kuwamura et al., in the J. of Am. Oil Chem. Soc.
51, 29-34 (Feb., 1971), described block copolymers of ethylene oxide and polyoxytetramethylene glycols prepared by cationic polymerization of tetrahydrofuran as being solids with surfactant properties albeit with rather high pour points and poor defoaming action.

- 2 ~ 3 Grief et al., in U.S. Patent 4,038,296, described modified block copolymers of THF and EO which included a long chain ~C8-C21) alcohol. Their product was defined as R-X in which the hydrophobic portion, R, was provided by the long ch~in hydrocarbon radical of the alcohol, and the hydrophilic end, X, was provided by the reaction product of the THF and EO monomers. These copolymers were disclosed to be useful as textile auxiliariec and surfactants.
Random copoly~ers of THF and EO, on the other hand, are liguids, but they do not exhibit the effective surface active properties which are characteristic of the corresponding block copolymers. Random copolymers of THF
and E0 are produced by copolymerizing a mixture of the monomers, or by adding one monomer to the other at a substantially constant feed rate.
Pruckmayr, in U.S. Patent 4,139,567, for example, described the preparation of random copolymers of THF and E0 using acidic resins as catalysts for the polymerization. The disclosed process involved precharging THF and the resin catalyst and then slowly bubbling in gaseous EO at a substantially constant feed rate ovex a two-hour period while holding the reaction mixture at 25C.
Langdon et al., in U.S. Patent 4,183,821, disclosed random-block copolymers of THF and EO which were prepared by a two-stage process. The first stage of the process comprised forming the random hydrophobic portion of the polymer by reacting a mixture of THF and E0 in the presence of a Lewis acid catalyst. The hydrophobic segment then was capped with a hydrophilic block of ethylene oxide units by a base-catalyzed reaction with EO. The product was a random-block copolymer characterized by an abrupt breaX between its hydrophobic segment and its hydrophilic cap. Demulsifying properties were observed for such polymers but it was not apparent that they had effective surfactant properties.

3 ~r ~ ~3 ~ ~ J Ç ~

Knopf et al., in U.S. Patent 4,195,167, disclosed the formation of gradient copolymers of ethylene oxide and propylene oxide which were considered as intermediate between block and random copolymers. Such gradient copolymers of ethylene oxide and propylene oxide were produced by a process in which one of the premixed concentrations of the primary and secondary polymerizable monomer feed compositions was continuously changed during the polymerization. However, a suitable process for preparing liquid copolymers o~ tetrahydrofuran and ethylene oxide having effective surfactant properties was not disclosed.
The following references are also of interest in this field: U.S. Patents: 3,133,095; 3,194,772; 3,254,056;
3,344,088; 3,359,332; 3,425,999; 3,644,567S 3,83~,935;

4,065,520; 4,118,326; 4,198,464; 4,259,405; and 4,299,993 Brit. Pat. No. 854,958; Japan Patent Announcement No.
213-1977; and an article by ~urbach, W. and Adicoff, A. in Ind. & Eng. Chem., 52, 7725 (1960).
None of the above cited references, however, disclose, describe or suggest a suitable method for preparing copolymers of THF and E0 which are liquids at ambient te~peratures, and which exhibit effective surfactant properties, i.e. surface tension reduction, low pour points, good defoaming action, and effective lubricity, and wherein such copolymers exhibit these advantageous surfactant propertie~ over a wide range of molecular weights and monomer content.

~ f * ~

Accordingly, an object of the invention is to provide liquid surfactant polymers of THF and EO which are effective surfactants over a wide molecular weight range, and, particularly, which exhibit sub~tantial surface tension reduction, low foaming, low pour points, and useful lubricity surfactant properties.
Another object of the invention i~ to provide a process for making such liquid surfactant polymers.
These and other objects and features of the invention will be made apparent from the following summary and description of the invention.

SUMMARY OF THE INYENTION

The present invention provides a liquid surfactant polymer product which is substantially a copolymer of THF
and EO monomers (mer) units. The polymer structure comprises:
(1) a hydrophobic central THF-EO copoly~er segment containing predominately THF mer units, (2) tran~ition THF-EO copolymer seqments extending outwardly from the central copolymer segment characterized by a continuously increasing EO mer unit content relative to the THF mer units therein, and (3) hydrophilic termini polymer segments of substantially EO mer units.

Th~ liquid surfactant polymers of th~ invention have useful surfactant propertie~, including ~urface tension reduction, low foaming, low pour points, and effective lubricity, within a polymer molecular weight range o~ about 500 to 10,000, and, preferably, about 1,500 to 5,000.

The invention also provides a multi-stage proces~
for making the liquid surfactant poly~er product described herein. In this process, predetermined amounts of EO are added successively to a charge of THF at selected rates.
Polymerization is carried out in a predetermined manner at the various stages of the process to form the desired segments of the polymer.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a graphical illustration of the process of the invention, showing the rate of addition of EO to a charge of THF at each stage of the process.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated in the FIGURE, a 3-stage process is provided for preparing the liquid surfactant polymer product of the invention. During the several stages of the process, three segmentC of the polymer are provided, each with a predetermined monomer content.

CHARGE

The process is carried out by first charging a reactor wit~ T}IF monomer reactant and a small amount of a starter compow~d for the polymerization. The starter will enable linear polymerization of the monomers in one or more directions, depending upon the number of reactive hydrogens in the starter. Suitably, the starter is added in an amount of about O.l-10 mol % of all monomers present in the reaction. Representative starter compounds include - 6 ~ r~

monohydric or polyhydric alcohols, alcohol, such as butanol, ethylene glycol, butanediol, decanediol , glycerol, pentaerythritol, bi~-phenol A, nonyl phenol, polyethylene qlycol, polypropylene glycol, polytetrahydro~uran, and the like, and ~onobasic and polybasic acids, such as acetic acid, stearic ac$d, succir,ic acid, oxalic acid, gluaric acid, benzoic acid, and the like, although others known in the art ~ay be used as well, including primary and secondary amines, hydroxyl amines, and water. The reactor is then sealed, purged with nitrogen, and warmed to a reaction temperature. Suitably, the reaction temperature is set above the boiling point of EO (10C.) and below about 80C., preferably about 45-60C. A polymerization catalyst then is added, such as a Lewis acid, of which BF3-etherate is one example.

HYDROPHOBIC CENTRAL SEGMENT

The EO monomer reactant then is introduced slowly into the charged reactor at a low EO pressure, as shown by stage A in the FIGURE. Suitably, the EO pressure does not exceed about 2 psig, and preferably less than 1 psig.
During introduction of the EO monomer, in thi~ stage of the process, the reaction temperature gradually increases, generally, from about 45C. to ~bout 50-60C.
Copolymerization is thereby effected between the charged THF reactant and the small amount of added EO to ~orm the hydrophobic central segment of the polymer which contains predominately THF mer units. The EO addition is continued until about 1/2 to 2/3 o~ the THF charge i8 consumed. This segment preferably includes, relatively, about 10-20 THF
mer units to about 2-4 EO mer unlts.

- 7 ~ r~

TRANSITION COPOLYMER SEGMENTS

Substantially all of the remaining THF reactant then is copoly~erized with newly added EO, in stage B, to form the transition THF-EO copolymer segments of the polymer which extend outwardly from the central copolymer segment. These transition segments are characterized by a continuously increasing EO mer unit content relative to the THF mer units therein.
To form the transition segment~, the rate of EO
addition is increased slowly, for example, up to about 5-8 p6ig ., over a period of about an hour, as shown in the graph. The EO addition during this stage may be carried out in one step, shown as step B', or, in two successive steps, B " and B " '. In the latter pathways, the EO
reaction pressure is increased to the desired level (during step B ") and then it is held constant (during step B'''~
for a given period of time at the reaction temperature. At the conclusion of stage B, sub~tantially all of the remaining THF charge is consumed to provide the transition segments. Generally, ~he transition segments preferably include, relatively, about 4-15 THF mer units to about 4-30 EO mer units. The EO mer unit content in these segments continuously increase outwardly and away from the central segment.

HYDROPHILIC TERMINI SEGMENTS

Upon determination by analysis that substantially all the THF charge has been consumed in stage 8, the transition segments then are capped with hydrophilic EO
polymer ter~ini segments during stage C of the process.
These caps are provided by feed~ng EO into the reactor at an increased rate. Generally, stage C also is carried out in two steps, namely, step C', in which the EO pressure is ~.~ ~ F,~ J r increased substantially, e.g. to about 20 psig, and step C", wherein the remainder of the E0 reactant is added.
~he termini segments preferably contain about 3-40 E0 mer units, although lower and higher amounts also may be present.
ISOLATION OF PRODUCT

The reactor then i8 purged with nitrogen, cooled, e.g. to about 35C., and the reaction produ~t i8 discharged. The reaction then is terminated by complexing the catalyst for example, with a diatomaceous earth or by ion-exchange. The reaction product mixture then is stirred, filtered and vacuum stripped of volatiles. The polymer product obtained thereby is a clear, colorless ~iscous liquid, containing, relatively, about 14-35 THF mer units to about 9-100 E0 mer units.
The molecular weight of the polymer product suitably is about 500 to about 10,000, and preferably about 1,500 to 5,000. The product exhibits excellent surfactant properties of substantial surface tension reduction, low foaming, low pour points, and effective lubricity.

The invention will now be described by refarence to the following examples.

A dry, stainless steel reactor was charged with 256 g. (2.8!5 moles) of butanediol and 8,616 g. (119 moles) of THF (maxLmum water content of 0~01%). The reactor was sealed, purged wlth nitrogen and warmed to 45C. Then a solution of 10 g. of boron trifluoride-etherate in 15 ml.
of diethyl ether was added.

_ 9 _ Ethylene oxide (3,258 g., 74 moles) then was slowly pumped into the reactor at a slow rate such that the reaction pressure was about 1 psig. This pressure corresponds to an E0 flow rate of approximately 300 g. of E0 per hour. During the addition, the reaction temperature gradually increased to about 50-60C. After 4 hours, approximately 1200 g. of ~o had been added for copoly~erization with the charged THF reactant.
The xate of E0 addition then was slowly increased during about an hour S9 that a reaction pressure of about 5-8 psig wa~ reached. Thereafter, the reaction mixture is maintained at this pressure for 3 hours while the reaction' temperature was controlled at 60C.
The rate of E0 addition then was increased within a period of about 15 minutes until the reaction pressure reached about 20 psig. Meanwhile, the reaction temperature was controlled at 60C. The remaining E0 reactant then was added for about 2-1/2 hours. Then the ~ixture was stored for an hour.
The reaction product was then purged with nitrogen for 15 minutes, cooled to 35C., and discharged. Magnasol (50 g.) was added and the mixture was stirred for 2 hours at 65C. The Magnasol was removed by filtration and the product was vacuum stripped at 60C. with a slight nitrogen sparge. The product was a clear, colorless, viscous fluid.

Tle procedure of Example 1 was followed using different amounts of the THF monomer reactant, initiator and catalyst, and E0 rate of addition. The products obta~ned were liquid surfactant polymers of varying molecular weights having effective sur~actant and other physical properties.
The process parameters of Examples 1-10 are shown in Tables 1 and 2 below.

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O ~ ~ cn ~ _ O
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-1 ~ 1~ 0 0 ~ ~ _ ~
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~ ~~ ~ ~ ~n ,~ .
E~ E~
U~

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(a O c, u~ In O U~ In o o o ~ ~ In 0 ~ O ~ U~
L~ ~ _I ~1 O (a t~l ~ N N N N N. ~1 N

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~ . ~ o ~ ~ ~r , :~: ~o o ~ ~4 o ~ ~ a~

. .
z The ~olecular weights, surfactant and other physical properties of the polymers of the invention are shown in Table 2 below.

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~ ~ o ~ ~ o ~ ~ ~ ~
~ ~ ~ ~ ~ ~ u~ ~ ~ ~
E~
,~ ~ o In ~ ~ I~
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O ~ ~rl ~ OD ~ O
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a~
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P- U I I I I I I
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O ~. ~ U~ O ~ O o U~ O o O o ~æ Ei :~: O ,~
o~ ,~
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~ ~ O O O O O O O U~ o o - O ~ o u) a~ ~ O O O 1` ~ ~ ~ ~ ~
o o ~ ~ o ~
as -- ~ a~ ~ ~ ,1 u~ ~ o ~n ~1 .,, ,~ o :~ C~
o o o o o U o U~ o o . U~ ~ ~ ~ o ~ t~ ~ o O ~ 1` a~ O ~ I
X :~ ~ ,1 _1 ~1 ~ ~ q~ ~ U~ ~ I I
. >' ~ri ~ ~ .
3 Cu~
.-~ ~ ~ er U'~ 0 ~ I h ~ o ~
X Z

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The results in Table 2 show that the liquid surfactant polymers of the invention have excellent surfactant properties, as evidenced by the substantial surface tension reduction. In addition, these surfactants exhibit low foaming, low pour point and excellent lubricity properties~
~ lthough the invention has been described with reference to certain embodiments thereof, it will be unde~stood that changes and modifications may be made which are within the skill of the art.

Claims

1. A liquid surfactant polymer product consisting essentially of:

(a) a hydrophobic central THF-EO copolymer segment containing predominately THF mer units, (b) transition THF-EO copolymer segments extending outwardly from said central copolymer segment characterized by a continuously increasing EO mer unit content relative to the THF mer units therein, and (c) hydrophilic termini polymer segments of substantially EO mer units.

2. A liquid surfactant polymer product according to claim 1 wherein (a) includes, relatively, about 10-20 THF mer units to about 2-4 EO mer units; (b) includes, relatively, about 4-15 THF mer units to about 4-30 EO
units, and (c) includes about 3-40 EO mer units.

3. A liquid surfactant polymer product according to claim 2 wherein the polymer includes, relatively, about 14-35 THF mer units to about 9-100 EO mer units.

4. A liquid surfactant polymer product according to claim 1 having a molecular weight of about 500 to about 10,000.

5. A liquid surfactant polymer product according to claim 4 having a molecular weight of about 1,500 to about 5,000.

6. A liquid surfactant polymer product according to claim 1 wherein (a) segment includes a starter compound.

7. A liquid surfactant polymer product according to claim 6 wherein said starter compound is selected from a monohydric or polyhydric alcohol and a monobasic or polybasic acid.

8. A liquid surfactant polymer product according to claim 7 wherein said starter is butanediol, glycerol, butanol or decanediol.

9. A liquid surfactant polymer product according to claim 1 which is a colorless viscous liquid.

10. A liquid surfactant polymer product according to claim 1 which exhibit substantial surface tension reduction, low foaming, a low pour point, and good lubricity properties.

11. A process for making the liquid surfactant polymer product of claim 1 which comprises:

(a) copolymerizing a charge of THF with a predetermined amount of EO to form a hydrophobic central copolymer segment containing predominately THF mer units, (b) copolymerizing substantially the remainder of the THF charge with an increased amount of EO
to form transition copolymer segments extending outwardly from the central copolymer segment and characterized by a continuously increasing EO mer unit content relative to the THF mer units therein, and (c) forming hydrophilic termini polymer segments containing substantially EO mer units.

12. A process according to claim 11 wherein step (b) is carried out with an increasing amount of EO monomer reactant.

13. A process according to claim 11 wherein step (b) is carried out by increasing the amount of EO monomer reactant and then holding at a given level for a predetermined period.

14. A process according to claim 11 wherein step (a) is carried out in the presence of a starter compound.

15. A process according to claim 14 wherein said starter compound is selected from a monohydric or polyhydric alcohol and a monobasic or polybasic acid.