FR2490649A1 - PROCESS FOR PREPARING HYDROPHILIC POLYMER GEL OF HIGH MOLECULAR WEIGHT - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR PREPARING A GEL OF HYDROPHILIC POLYMER OF HIGH MOLECULAR WEIGHT WHICH CONSISTS OF POLYMERIZING THE MONOMER (S) OF THE POLYMER IN AN AQUEOUS MEDIUM WITH A COMPATIBLE ORGANIC SOLVENT AND A VINYL MEDIUM OF FORMULA 5 (95) CONTAINING: CF DRAWING IN BOPI) AND CORRESPONDINGLY 95 TO 5MOLES OF PATTERNS OF FORMULA: (CF DRAWING IN BOPI) OR R AND R INDEPENDENTLY REPRESENT A HYDROGEN ATOM OR A LOWER RADICAL ALKYL, R REPRESENTS A RADICAL ALKYL 8 COMPATOMORTANT CARBON AND REPRESENTS A HYDROPHILIC RADICAL OR A QUATERNIZABLE RADICAL SUCH AS A PYRIDINO OR IMIDAZOLINO RADICAL.

Description

The present invention relates to a method for

  to prepare a hydrophilic polymer gel of molecular weight

high eyelid.

  The hydro gel polymer gel preparation

  High molecular weight, especially polyacrylamide, by discontinuous polymerization of an aqueous monomer solution under adiabatic conditions, has been known for some time. In general, the gels contain 25 to 40% by weight of solid material, the balance being water. The removal of the water was carried out

  by treatment with an organic solvent, which naturally

  This increases the cost of the process and introduces an element of risk. Otherwise, it is possible to dry these gels with hot air, but the difficulty of this process is that the gel dries and disintegrates due to its tacky nature and the particles tend to adhere to each other, which makes the drying complete extremely difficult and in many cases almost impossible. A method is therefore sought to obtain gel particles having little or no tendency to stick together and that

  therefore one can hide by hot air.

  The invention relates to a method for pre-

  parry a hydrophilic polymer gel that consists of poly-

  merit monomer or monomers in a medium

  aqueous solution with a compatible organic solvent and a copolymer

  organic vinyl mother as defined below. The organic vinyl copolymers used in the process of the invention comprise 5 to 95 mole% of units of general formula Rl

CH2- C

  COOR 2 and correspondingly 95 to 5 mole% of units of formula: R 3

CH2 C

c2, I Y

  R1 and R3 independently represent a hydrogen atom

  gene or a lower alkyl radical, i.e., having 1 to 4 carbon atoms and preferably

  methyl radical, R2 represents an alkyl radical comprising

  at least 8 carbon atoms, typically the stearyl radical, and Y represents a hydrophilic radical or a quaternizable radical, in particular -OH, -COOH or

  an alkali metal, ammonium or amine salt corresponding to

  a heterocyclic radical such as pyridino or imine

dazolino, or a radical of formula:

R5

-COO (CH2) x-N X- or -CO (CH2) -N

R6 NR6

  R7 o x is 1 to 4, preferably 2 to 4, R5, R6 and R7 are independently lower alkyl or hydrogen and X is an anion,

  typically anion chloride, methylsulfonate, ethyl-

  sulphonate or a half anion sulfate, for example the

  radical -COC2H4N (C2H5) 2. Moreover, Y can also represent

sit -CONH2.

  The copolymers used in the process of the invention are therefore addition polymers of the vinyl type. The correct balance of hydrophilic groups

  and hydrophobic in the polymer chain is important.

  To achieve this balance, a mixture of a long chain fatty ester, typically an acrylic or methacrylic acid ester, such as

  methacrylate or stearyl acrylate, and a mono-

  mother generally soluble in water, such as acid

  acrylic acid or methacrylic acid or a methacrylate salt

  alkyloxytrimethylammonium, typically

  methosulphonate in the indicated molar proportions.

  Of course, the cationic esters may be in the quaternized form or in the form of a salt such as the hydrochloride. A copolymer which is preferred for use in the process of the invention is derived from stearyl methacrylate and dimethylaminoethyl methacrylate, and is typically prepared in a molar ratio of 1: 1.25. This copolymer is typically used either after neutralization with hydrochloric acid or after quaternization with dimethyl sulfate, but of course it can be used in the form of

the free amine.

  The molecular weight of the copolymers is generally between 1,000 and 500,000, preferably

between 1,000 and 15,000.

  The copolymers used in the process can be prepared according to conventional techniques such as addition polymerization, typically in organic solvents such as paraffinic solvents.

  or chlorinated solvents such as tetrachlorethylene.

  As previously indicated, the preparation is

  gels in an aqueous medium in the presence of an organic solvent

  compatible. The term "compatible" means an organic solvent which is not

  with none of the materials present in the reaction medium. An organic azeotropic solvent is preferred with water, in particular forming an azeotrope between 60 and C. Typical organic solvents include perchlorethylene, hexane, whitespirit, benzene, toluene and xylene. but of course these

  Solvents must be compatible with the copolymer.

  The polymer monomer or monomers

  ser are generally present in the aqueous medium at a concentration of 15 to 90% and preferably 25 to 75% by weight. The pH of the solution can vary over a wide range but typically is between 2 and 8.5, especially between 6 and 8.5. We can perform

  polymerization under adiabatic or iso-thermal conditions

  baths; it is carried out typically at a temperature of 10 to 110 C and more particularly of 10 to 90 C.

  usually helps polymerization by the use of amorphous

  standard, including redox, persalt and azo initiators such as azobisisobutyronitrile, azobiscyanovaleric acid, ammonium persulfate and

  azo-2,2'-bis (2-amidinopropane) hydrochloride.

  The concentration of the initiators depends

  of their nature. Amortization is appropriately used.

  azo in quantities of up to 2000, for example

  from 10 to 2,000 and more particularly from 500 to

  1000 ppm by weight (based on the weight of the monomer

  feel). In the case of persalts, the concentration is generally from 20 to 200 and in particular from 50 to 100 ppm by weight and for ferrous and ammonium iron sulphate it is typically from 1 to 100 and preferably

from 5 to 50 ppm by weight.

  In general, the method of the invention

  applies to obtaining hydrophilic polymer gels.

  However, the invention is particularly useful for preparing acrylamide polymer gels. The term "acrylamide polymer" encompasses not only acrylamide homopolymers, but also copolymers

  acrylamide containing other monomeric units.

  Suitable comonomers include acrylic acid and methacrylic acid, quaternized aminoalkyl acrylates and methacrylates, as well as

  quaternized vinyl nitrogen heterocyclic compounds.

  Typical examples of monomers are: (a) acrylic acid and its alkali metal or amine salts,

  (b) dimethylaminoethyl acrylate or methacrylate

  of dimethylaminoethyl quaternized with dimethyl sulphate or methyl chloride, (c) methacrylamidopropyltrimethylammonium chloride, (d) quaternized vinylpyridine or vinylimidazoline

  with dimethyl sulphate or methyl chloride.

  Other hydrophilic polymers which can be prepared in the form of a gel consist of homopolymers of

  monomers indicated in paragraphs (b), (c) and (d) below.

  above. A surprising feature of the invention is that the cationic copolymers used to facilitate the production of the gels can be used to prepare acrylamide polymers.

anionic as well as cationic.

  The method of the invention makes it possible

  to hold polymers having a high molecular weight generally of the order of 1 x 10 and it is possible to obtain

  molecular weights up to 1 x 107 or higher.

  As soon as the polymerization is complete, the gel is generally divided into particles having the size

  desired, typically not more than about 0.5 cm.

  In general, the particles can be easily dried in hot air without sticking together and in this respect it should be noted that the organic solvent present, especially when it forms an azeotrope with water, facilitates the operation. drying. In addition, contrary to the previously proposed methods according to which the solvent is used to dehydrate the gel, the solvent used is not necessarily toxic and / or flammable. We can then, if we wish, grind

the dried material.

  The invention is illustrated by the examples

following non-limiting

EXAMPLE 1

  0.6 kg of acrylic acid are dissolved in 5.76 l of deionized water. The pH is adjusted to 6.0 with a

  solution of caustic soda while cooling for

  keep the temperature below 30 C. This solution is dissolved in 2.4 kg decylamide and a final pH adjustment is made at 7.2. 0.16 kg of a 56% solution in the white spirit of a copolymer is added with stirring.

  of stearyl methacrylate and dimethyl methacrylate

  aminoethyl (molar ratio: 1: 1.25; molecular weight

  about 5,000). The temperature is at this stage of 12cC.

  The solution is purged with nitrogen for 20 minutes and 80 ml of methanol, 50 ppm of

  ammonium persulfate, 600 ppm azo-2,2'-hydrochloride

  bis (2-aminopropane) and 25 ppm ferrous iron sulfate and ammonium (all amounts of the initiators being expressed relative to the monomer). The initiators are added as dilute aqueous solutions. The temperature is 90 ° C. The polymerization is carried out in a well-insulated steel vessel which retains heat sufficiently for the polymerization to proceed.

finishes.

  Fragment the gel into particles

  less than 0.5 cm. Particles do not tend to adhere to each other when pressed by hand or placed under a load of 1 kg. The material has a waxy character to the touch. Dry in a laboratory hot air dryer to a

10% humidity.

  The material produced presents an excellent

  solubility and has a molecular weight measured by

  intrinsic cosity of 8.5 million.

EXAMPLE 2

  A solution of 3 kg of acrylate is prepared

  amide in 7 kg deionized water with the same copoly-

  mother of stearyl methacrylate than in Example 1.

  The pH of the solution is adjusted to 5.0 with hydrochloric acid. Adiabatic polymerization is carried out

as in Example 1.

  The gel obtained after disintegration has excellent non-adhesion properties and the gel particles can be dried directly in hot air to obtain a moisture content of 12%. The polymer is soluble in water and has a molecular weight of 5 million.

EXAMPLE 3

  A solution of 3.75 kg of acrylamide in 9.5 l of deionized is prepared. 0 kg of a 75% solution of acryloyloxyethyltrimethylammonium methosulphate is added. 1 kg of a

  25% solution in hexane of a methacrylate copolymer

  stearyl and diethylaminoethyl acrylate (

  molar port 1 / 1.25). 200 g of dimethyl sulphate are added and the mixture is stirred for 10 minutes. The solution is purged for 20 minutes with nitrogen and then 0.5 kg of methanol, 25 ml of a 5% solution of ammonium persulfate and 30 ml of a solution are added in order.

  1% solution of ferrous iron sulphate and ammonium.

  There is a rapid exothermic thrust at 105 C in 2 minutes with release of water vapor. The final solids content of the gel block is 70%. The gel is cut into small particles that are not tacky and dried with hot air up to 12%

  of moisture to obtain a water-soluble polymer.

EXAMPLE 4

  The procedure of Example 1 is repeated except that the stearyl methacrylate copolymer is replaced by a copolymer of acrylic acid and stearyl methacrylate (molar ratio of 1.3: 1) in the stearyl methacrylate copolymer. hexane. The polymerization evolves in a similar way and produces a gel which after disintegration has not

tendency to re-adhere.

  Naturally, various modifications may be made by those skilled in the art to the devices or methods which have just been described solely by way of non-limiting examples without departing from the scope of the invention.

Claims (9)

  1. Process for preparing a poly-gel   hydrophilic mother characterized in that it consists of poly-   to merit the monomer (s) of said polymer in an aqueous medium with a compatible organic solvent and a vinylic copolymer comprising 5 to 95 mole% of units of general formula: R CH2 C   COOR 2 and correspondingly 95 to 5 mole% of units of formula: R CH C Y   R1 and R3 independently represent a hydrogen atom;   gene or a lower alkyl radical, R2 represents an alkyl radical containing at least 8 carbon atoms and   Y represents a hydrophilic radical or a radical quater-   nisable such as a pyridino or imidazolino radical.   2. Method according to claim 1,   characterized in that a gel of homo- or co- acrylamide polymer.   3. Method according to one of the claims   1 or 2, characterized in that R1 and R3 represent   independently a hydrogen atom or a methyl radical.   4. Process according to any one of   Claims 1 to 3, characterized in that R2 represents the stearyl radical.   5. Process according to any one of   Claims 1 to 4, characterized in that Y represents   -OH, -COOH or an alkali metal, ammonium or   corresponding amine, -CONH 2, a pyridino or imine radical dazolino or a radical of formula: R R5    / R / R - COO (CH 2) = N X or - CO (CH 2) - N --COO (OH 2) x 7 R6 R6   o x has a value of 1 to 4, R5, R6 and R7 independently represent a lower alkyl radical or an atom   of hydrogen and X represents an anion.   6. Process according to any one of   preceding claims, characterized in that the   vinyl copolymer derived from stearyl acrylate or methacrylate and acrylic or methacrylic acid or   methacryloyloxyethyltrimethylammonium salt.   7. Process according to Claim 6, characterized in that the vinyl copolymer is drifting   of stearyl methacrylate and dimethyl methacrylate   aminoethyl in a molar ratio of about 1: 1.25.   8. Process according to any one of   preceding claims, characterized in that the   organic solvent is perchlorethylene, hexane,   white spirit, benzene, toluene or xylene.   9. Process according to any one of   preceding claims, characterized in that   prepares a polymer gel having a molecular weight at least 1 x 106.