BE621583A - - Google Patents

Description

       

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  "PROCESS FOR PREPARING AGGREGATES OF DR POLY-SACCHARIDES DERIVATIVES AND AGGREGATES THUS OBTAINED"
The present invention relates to a method of preparing ce aggregates derived from finely divided polysaccharides,

     insoluble in water and capable of forming stable colloidal dispersions *
Aggregates of cellulose crystallites eventually split capable of providing aqueous dispersions and

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 EMI2.1
 stable gels are found in US Pat. No. 8,29978 * 446 filed January 28, 1957. These cellulose crystals aggregate 80 have been found to be extremely useful as a calorie-free additive. for foodstuffs, Ccmmt 'component of mixture for cosmetics and preparation. pharmaceuticals and for a variety of other uses.



     It $ cannot in general be disaggregated enough
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 mont to lead to colloidal particles k unless one uses methods of grinding or sag reduction requiring considerable energy and operating time one must carry out the same degradation of cellulose or polymers cellulosics,
Derivatives of polysaccharides insoluble in
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 119 * u, obtained according to the present invention, forming * stable colloidal dispersions and thixotropic gels by attrition * Aggregates of cellulose derivatives
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 capable of leading to stable gels,

   obtained according to the present invention, exhibit improved strength
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 . syneresis and bacterial attack, "
The process for preparing according to the present invention a material derived from a polysaccharide capable of
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 to lead to stable gels allows some control of the opacity of the gels formed from said material and comprises the transformation of a polysaccharide into water-insoluble derivatives and the degradation of said derivative by treatment of the mild hydrolysis type, sufficient to give a material capable of leading, after attrition, to a table colloidal dispersion in an aqueous medium.

   The process according to the present invention allows the production of material capable of conducting gels with high yields.
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 higherea. It provides polysaccharide aggregates * which

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 the l \ o14j: ul .. possess * - hydrophilic groups * which> increase the stability of the product in the aqueous * composition *, it "," * The procedure according to the present * invention perwit '#; '. // to choose the degree of opacity of the foliated gels starting from * / aggregates in aqueous medium, by variation of the dogré of <#, "%,." substitution (D * So) to the lower range of * 9 .. '* The resulting profit is a batting material, ..'. of aggregates, capable of leading to freezes $ much, more stable * fH? 1 and which, in August, forms of freezing,: delay * 'the' syndxto *. 1 * # in many cases it has a tehd.nè..úppl48., T.! I '..;

   ','. resist attack by bacteria, this tendency being a function of the nature of the * substituted * groups of the .ut, and .. pellet * 1 "1 .. .., fi ', Ù These products can tilt ** as as;.> / & Carrier material for * cosmetic * and pharmaceutical agents, both dry and hydrated, it can add to foodstuffs or serve as a mixing agent, otlm the nature of the ingredients. group, substituents, They are useful as
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 filler for molding resins and for a variety of other applications.



  In the field of the invention, it is possible to use
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 some water-insoluble polysaccharide materials, such as cellulose, amylettu 1. chitin,. xyls and mannan * Since cellulose * has been the preferred base material for its low price and flexibility, the invention will be more particularly useful. pat.
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 cooking with cellulote taken as an example.



  Source materials for cellulose include pulp from bowls, such as sulphite bleached pulp
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 and sulfate celletianchie, natural fibers * such *.

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 that ramie, cotton and cotton purified and purified cellulose or chemical cellulose which are prized * in the form
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 a rather high purity granulated material having a high density per volume.



   The derivatives obtainable according to the process of the present invention include, for example
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 4thera-oxides of cellulose including (0-alkyl) g (ty-eryl,) and (..aryialyi) celluloses - such as (0-methyl) cellulose, (O-dthyl) cellulose, (O-propyl) cellulose , (O-butyl) cellulose, (0-atnyl) cellulose, (t1-pbenyl cellulose, (0-benzol) cellulose c3..mthyl 0-propyl) cellulose and (0-methyl-C-benzyl) cellulose, the 0 - (hydroxyolkyl) j celluloses comprising comne group * hydroxyalkyl groups t hydroxym4thYl, hydroxy4thyl., hydroxypropyto, hydroxybutyl hytxoxppxcpy, butyl * # hydroxy. propyl ethyl and hydroxyethyl hydroxy propyl the 0-earbo (xyalkyl) celluloses comprising the 4 (c.srbaxymthyli, o-cerboxy 4thyl] t and o- (carboxypropyl) celluloses;

   0 - '(a).': oxyalkYl) celluloses comprising t- (ethaxyethyl), o- (propyloxylthyl) and 0- (benzyloxy ethyl) celluloses 1 thiour4thanes of cellulose comprising cellulose thlourethane, N- cellulose thylth1ourthae, cellulose N-phenylthiourethane and cellulose N-ethyl N-phenylthiourethane cellulose esters including cellulose acetate, cellulose formate, cellulose propionate, cellulose butyrate, mixed esters cellulose and acetic and butyric acids, acetic acids and
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 propionic, acetic and atearic acids, 0- (hydkoxypropyl) cellulose acetate, (0-benzyl) acetate

   cellulose 1 and derivatives of partial oxidation of cellulose
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 for which the substituent group is attached to a unit

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 anhydroglucose of the dellulotic chainb C08ptêAlftt of derivatives * substituted by * aldehyde groups, aarcIi1 or both together * Generally the above described * can be prepared according to any, which commonly known method to lead to a product insoluble in> ##>
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 the water,,
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 O-aiky, or 3-axyi celluloses are prepared by treating the cellulose with an ioen.



  Suitable alkylation comprising, for example, the alkyl fractions, tislky3 sulfata, and bonzyl o halogdwits in the presence of an alkaline catalyst, by sodium hydroxide. Mixed ethers are obtained by using a mixture of alkylating agents during the dvdthdeietcation process. O-, hydroxy alkyl) cells ** can be obtained by mixing the cellulose with an etlkyHn * oxide under pressure. while C- (alkoxy alkyl) and eylacy .1kyl) celluloses are prepared by alkylation of d4ri '..: 0- (hydroxy4lkyl) * 0- (carboxy alkyl) celluloses are produced., ¯ by reaction of cellulose and a .11ph.t- acid substituted by a halogen, for example monochloraaitiqut; and a base.

   The esters of cellulose are h.b1tuel1..I.t pr4par4. by treatment of cellulose with the anhydride of a particular acid, for example acetic anhydride, prop1
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 nique and butyric.



  Mixed esters are prepared using
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 mixed acid anhydrides. The reaction can be carried out using an acid or an alkali catalyst. The subst4m derivative
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 killed by an aldehyde group are suitably prepared by
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 treatment of cellulose with periodic acid while
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 the derivatives substituted by a carboxyl group can be

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 prepared by treating cellulose using nitrogen dioxide.



   It is usual to facilitate the preparation of
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 derivative said cellulose by mixing or homogenizing the cellulose in an organic liquid medium which serves as a solvent for the etherifying or esterifying agent * When the reaction is complete, the derivative can be washed and dried.



   The cellulose derivatives prepared by a process implementing features of the present invention must be insoluble in water in order to be able to lead: the formation of gel or of dispersion after degradation by-
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 tielle and attritien. The degree of substitution for each derivative is critical to achieve the desired water insolubility.



   The degree of substitution denotes the average number
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 of substituents per anhydroglucose unit of the cellulose molecule which replace any of the three original hydroxyl groups of these units * Accordingly, the maximum degree of substitution is 3. In the field of the present invention, the DS of the derivatives of cellulose must be low enough to maintain the original water insolubility of the cellulose or high enough to be
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 Insoluble in water. The range of Dr, S, for each water insoluble cellulose derivative varies depending on the hydrophilic nature of the substituent groups.

   For example, the
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 D.S, maximum for 110-methyl cellulose Insoluble in water in the low range of D.S. is about 1 while
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 the range of De $, for o-4thyl cellulose insoluble in water can be up to. 0 # 5 approximately in the low range - and above 1.8 for the upper range * Water insoluble o (hydraxy- 'ethyl) cellulose po $ 6ed <t un De $ * maximum

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 in the lower range of D * So of about 0.8 and m P minimum in the upper range of about lCt t'aoetet '' 1i: of cellulose insoluble in water has an OS, '..x18t8 ,.; '.' of about 0.3 in the interval within do C <S <<tt a JMU, '- Minimum of about 1.2 in the interval tupdr1eut.

   The .. 1Qt, "'" valles de O.S. for the water insoluble cellulose derivative are well known to those skilled in the art and further description is not required.
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  The formation of derivatives, together with the cel; LMlose, favors the reduction of the length of the, chatmi d * Ir. ' .o14eul, cellulose 1 this dlm1nu.'149tfl "nt k4 need ** W additional chemical degradation- of 0.11u104., dt bzz b obtain a material which can be subjected to the att: d,: U, '.

   The derivative formation also high of tt6-m .Vf \ gR ". The yield of product, that is to say an at4riau # dgyata of c * Hulo e which can 't,"' 8oi .. Attitude <Water insoluble bedded cellulose d4rlv4a which are generally fibrous in character * have been partially degraded or reduced in chain length! by controlled hydrolysis. Hydrolysis can occur. be conducted by various methods, including the use of acids
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 and enxymet but it is preferable that the d4d'lf '4 1 ...

   cellulose is hydrolyzed with an aqueous solution of hydrochloric acid of low concentration * For example, the treatment of insoluble cellulose derivative $ binder
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 water with a (5% hydrochloric acid solution for 16 hours at 71 C # represents a degradation treatment ", 1 sufficiently effective for the purpose of the present invention.



  More vigorous conditions for shorter periods of time also produce similar returns

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Under operating conditions, for example, a 2.5% HCl solution is used to treat the cellulose derivatives for one hour at 121 ° C. under pressure to produce a material capable of being subjected to attrition. The partially degraded derivative is neutralized with a weak alkaline solution and washed with water.



   In comparison with the materials based on cellulose crystallite aggregate previously mentioned in US Pat. No. 2,978,446, the cellulose derivatives degraded according to the present invention are not characterized by an average degree of polymerization or a length of stable medium chain.

   The degraded cellulose derivatives retain some amorphous regions of the cellulose material and are not fully crystalline. However, they are sufficiently degraded to give a material capable of being subjected to attrition by mechanical disintegration means with negligible amount of energy to result in cellulose aggregates having a colloidal particle size.

   The mechanical decay of derivatives, as mentioned above, can be conducted in several ways, both by subjecting them) * to attrition in a mill or by subjecting them to the action * $ of super-fast cutting, or to the high pressure action of the order of at least 350-700 kg / cm2.



   The disintegration of the derivatives is carried out in the presence of a liquid medium although, when high pressure is used, such medium, although recommended, is not necessary. The suitable medium is water and. the mixture subjected to the recommended attraction contains at least about 20% water and at least about 3% of degraded material,

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 Other to be liquidated from pr4'x: enc. co stlbles, are suitable, 'comprising 1 ** solution * to kill * $ the polyols., parai l "qù .. glycerol is an exompl o los alcohols and more particularly ethanol Itt Lticopropinole Whatever the roof .'tbodt use # 4e # the disintegration is continued * until the aggregation is not possible;

   obtained are characterized by the formation of a. suspension <ti!} ble in aqueous medium has, .1 "of which '11 ..ont always attracted, or in which it $ can be * dispersed thereafter * By sugponston otatjo is meant a suspension from which aggregates * do
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 apparently not but to the care of which there $ z * are * 0 4iu * p # n4, sion 1nd4f1nim.nt, Izêma for periods of the order of 4 *, several weeks or months.

   For higher concentrations of aggregates, the suspension has a disperslon, tlnd1t, that for higher concentrations *, it is a gel * It is understood that within the scope of the invention the
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 The term “suspension” denotes both a dispersion * and a gel, the latter expressions being defined above all.



   The following examples are given by way of demonstration of the products and of the process according to the present * Invention * Example 1,
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 Several low-substitution 410- (hydroxypropylj ..11ulOl. Samples are prepared * by reacting 200 grams of purified wood pulp with 200 cm3 of
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 touàe, at 10% in a reaction vessel mechanically stirred for 45 minutes. Then a mixture of 50 cm3 of propylene oxide and 50 cm3 of éioxane is added to the alkaline derivative of cellulose.

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   Several different samples * are prepared by reactions at different temperatures and for varying reaction times,
The first test is carried out at ordinary temperature and lasts two hours.



   The second test lasts 6 hours at room temperature and the third test lasts hours at 67 C. Each of the above samples is then washed with a 50/50 acetone-water mixture, then with a 75/25 acetone-water mixture, followed by immediate washing with acetone. All samples are Insoluble in water. However, the third sample shows a very high degree of swelling.
All samples are washed with water to remove acetone, the solid concentration is adjusted to 35% relative to the aqueous suspension, and the mixture is subjected to 25 minute attrition in the HOBART mixer.



  In each case, the pastes obtained are extremely homogeneous and shiny with a wax consistency * Part of the material is subjected to attrition for variable solid concentrations up to 70%, and it is noted that, in each case, a material with the appearance of wax, which does not disintegrate, is collected,
The gels formed using the Hobart mixer are spread so as to reach 15% solid concentration and mixed for 7 minutes in a Mixmaster,

     The gels obtained resemble "cold cream" with a slightly more marked transparency * Thin sheets cast and dried from these gels have a texture similar to wax, Example% axez
50 grams of insoluble treated cotton wads

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 in water, commercially available, (0 -. (hydry <thY cellulose), are hydrolyzed using 2 liters of 10% chlorhyftic ttact4o to 70 * Co for 17 hours.

   Ap.t4 .. "Mechanical attrition of 30 minutes of a suspension to be concentrated in aolidn de'luO- (hydroxydtityl) cellulose h, 4lY. '.6., One obtains a Sky whose char.ctfr18tlque, are unique *, for a concentration of 51% in solid, the gel has 1.,
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 apparent viscosity of a thick * heavy, waxy, material;
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 extremely homogeneous and .table and remains as quo.tl near '. continuous kneading between the $ fingers * This' pmpxi <tt h -4mffyé% seems to be very suitable for bait <!% <relative * /, coometrics. . '! .-.'. "'
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 Example 3
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 75 gram $ of tr1ac "t.t .. of cellulose are bydtaJ.Vè4. By the action of 300 c * 3 of hydrochloric acid. 53K and heated pedantly 16 hits' 700 C.

   After hydrolysis, the sample is /, 'toumit at attrition in uliAl.ng.ur liobarte under font * of an aqueous oupenoion containing 35% of solid,. for 45 minutes then extended with f90n water. obtain 9 concentration of 15% in solid. The resulting mixture is then worked for 7 minutes in a 14ixDiattez * Cft obtains a homogeneous 0 *, shiny somewhat translucent, with 4 * cup syndrboe properties.
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  Example ¯ $
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 A sample of O- (hydroxydthyl) C'lll. ' low degree of substitution (0.05-0.06) is hydrolyzed # using a 5% hydrochloric acid solution for 16 hours at 700 C. O- (hydro) {yethyl cellulose hydrolyzed is then: 'Oum! 18 At attrition for 25 minutes in a 61an.Ut.

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 of Hobart in the form of a suspension containing 35% of solid *, After dilution with water, so as to reduce 1 concentration of solid to 15%, the mixture is then worked for 7 minutes in a Mixmaster.

   The homogeneous shiny gel obtained exhibits improved syneresis properties. The gel also exhibits a certain degree of transparency and takes on a bluish sheen. When gels containing high concentrations of solids of up to 70% are prepaid using the same material based on hydrolyzed O- (hydroxyethyl) cellulose as defined above, homogeneous gels are obtained with a solid appearance. wax,

     thick $ free of crumbs or similar substances *
The invention is not limited. to the examples described @ 11 is, on the contrary, general in scope and subject to variations and modifications *


    

Claims (1)

R E S U M E The present invention relates to: EMI13.1 1) A process for preparing a polysaccharide-based material capable of leading to the formation of a stable dispersion, wherein the polysaccharide is converted to an insoluble polysaccharide derivative of? water, the derivative is degraded by mild hydrolysis, sufficient EMI13.2 to obtain a Material could undergo the atrl1; J, pnt and the matriaa.s * t fell to mechanical attrition so as to produce colloidal particles * Such a method may further comprise separately or EMI13.3 in combination one or more of the following aa) - the polvsaccharid8 utility is cellulose tb) - the cellulose is alkylated, for example any drilled from an O- (hydroxyalkyl) cellulose b low degree of fub: t3, tu- tion: c) - the material that can be subjected to attrition is neutrality before mechanical attrition: EMI13.4 ci) - the degraded material is subjected to attrition you * form a mixture containing at least about 20% water and EMI13.5 at least about 3% of degraded material to wrap rr ', tr stable dispersion: II) - As a new industrial product, EMI13.6 polysaccharide derivative4 aggregates capable of forming stable colloidal dispersions *