MXPA01009920A - Enhanced gel strength methylcellulose - Google Patents

Abstract

In a first embodiment, the present invention is a process for producing methylcelluloses having greater gel strength than methylcelluloses of the prior art. According to the process of the present invention, methylcellulose is produced by methylating cellulose pulp in two separate stages. In a second embodiment, the present invention is a methylcellulose having a methoxyl substitution of about 29 to about 32 weight percent based upon the weight of the methylcellulose and a gel strength greater than about 223 x (v0.273), wherein v represents the viscosity of the methylcellulose.

Description

METHYL CELLULOSE WITH IMPROVED GEL RESISTANCE Field of the Invention The present invention relates to methyl celluloses having improved gel strength, processes for making said methyl celluloses and compositions containing said methyl celluloses. BACKGROUND OF THE INVENTION Cellulose ethers have been used as additives for food compositions and processes to provide physical properties such as thickening, freeze / thaw stability, lubricity, retention and release of moisture, film formation, texture, consistency, retention of shape, emulsion, bond, suspension and gelation. For example, methylcellulose has been used in food applications, since it was discovered that the thermal gel property of certain methylcelluloses are similar to the egg white cell. That is, the methylcellulose solutions go through a heat-catalyzed gelato very similar to that of the fresh egg white. In fact, there has been a need in the food industry to replace egg whites in food. This need has been motivated by several reasons, including health and religious reasons. An important characteristic of both egg whites and methylcellulose, in their ability to bind together food ingredients. It has been observed that the resistance to the gel of these two food hydrocolloids, is responsible for this binding force in food. Methylcellulose has partially met the industry's need to replace egg whites in certain food applications. However, the gel resistance of methylcellulose has been insufficient to replace egg whites in other food applications. Therefore, there remains a great need in the industry to replace egg whites in certain food applications, which until now have not been replaceable by conventional methylcelluloses (ie, known in the art). It is generally known in the art that methylcelluloses having a higher viscosity also have superior gel strength. The present invention is directed to methylcelluloses that exhibit significantly higher gel strength at a given viscosity than any methylcellulose of the prior art. The methylcelluloses of the present invention make possible the development of food compositions with superior bond, consistency, and retention. Summary of the Invention The present invention allows a person skilled in the art to use a methyl cellulose with superior gel strength at a determined viscosity. The present invention also allows a person skilled in the art to use a methyl cellulose with a lower viscosity at a given gel strength. Methylcelluloses that have higher molecular weights in (that is, viscosity) tend to bind moisture very tightly, which gives rise to a final formed food product having a dry sensation in a mouth. The present invention allows a person skilled in the art to improve the overall moisture and texture release of a food product formed using a methylcellulose with lower viscosity, while maintaining the required gel strength. In a first embodiment, the present invention is directed to a methyl cellulose having gel strength ("G") greater than 223 x (v. 73), wherein "v" represents the viscosity of methyl cellulose for an aqueous solution at 2 ° C. % at a temperature of 20 ° C. This ratio of gel strength to viscosity can be represented by the equation G '> 223 x (v. 273), where ">" means "greater than or equal to". The methylcelluloses of the present invention also have a methoxyl substitution of 21% to 42% with base e? the weight in methylcellulose. The gel resistances can be measured by dynamic rheometry. The elastic modulus component of the complex viscosity, is quantified in the measurement of gel strength. This dynamic elastic modulus represents the force component generally known as gel resistance ("G"). Techniques for measuring elastic modulus (storage modulus) are described in Thermal Gellation Kinetics of Methylcellulose and Hydroxypropylmethylcellulose in Aqueous Solutions, Carbohydrate Polymers, (Kinetics of Thermal Gelation of Methylcellulose and Hydroxypropylmethylcellulose in Aqueous Solutions, Carbohydrate Polymers), volume 26 , No. 3, pages 195 to 203, which is incorporated herein by reference. Unless otherwise stated, all gel resistances of the present specification were determined by measuring in a dynamic rheometer the elastic modulus of 1.5% by weight of an aqueous solution of methylcellulose.

In a second embodiment, the present invention is directed to a process for making methylcelluloses having a desired level of methoxy substitution. The process comprises the steps of: a) reacting a pulp of cellulose with a first quantity of aqueous alkali in a first quantity of methylating agent under reaction conditions sufficient to methylate the cellulose pulp to a first level of methoxyl substitution; which is about 20% more than the desired level of methoxyl substitution; and b) reacting the methylcellulose from the first level of methoxyl substitution, with a second amount of aqueous alkali and a second amount of a methylating agent under reaction conditions sufficient to methylate it to a second level of methoxyl substitution which is about 40% more than the desired level of methoxyl substitution. A third embodiment of the present invention is directed to food compositions comprising a methyl cellulose of the present invention. A fourth embodiment of the present invention is directed to a pharmaceutical capsule comprising a methyl cellulose of the present invention. The Figure is a graphic representation illustrating the elastic modulus of methylcellulose of the present invention and those of the prior art. The present invention provides novel methyl celluloses having a high gel strength for a given viscosity grade and a percentage of methoxyl substitution compared to that of conventional methyl celluloses. Preferred methylcelluloses of the present invention may also exhibit lower gelation temperatures than conventional methylcelluloses of equivalent viscosity and percentage of methoxyl substitution. Preferred methylcelluloses of the present invention may also exhibit longer casting times than conventional methylcelluloses of viscosity and equivalent substitution. The lower gelation temperature may be desired or preferred in some applications, although it is not an essential property of the present invention. The reduced gelation temperature is useful in manufacturing and food processing. The food compositions can be gelled at lower temperatures saving energy and processing times during the heating / cooling cycles. In addition, the food compositions can retain the shape in wider temperature ranges during processing. The gelation temperature is determined by heating 1.5% by weight of the aqueous solution of methylcellulose, and it is observed that a narrower temperature range in which the gelation takes place. The melting time, generally refers to the time required for a thermally formed gel of methylcellulose to melt while cooling to room temperature. A longer casting time may be desired or preferred in some applications, although it is not an essential property of the present invention. Longer melting time at room temperature is useful in food processing and manufacturing. The gelation can be maintained in a wider temperature range and better and more durable texture retention is possible during the processing and consumption of the food. The melting time is determined according to the following: providing 15 grams of a 1.5% by weight of an aqueous solution of methylcellulose in a 20 milliliter container; Heat the solution for 8 minutes in boiling water - the solution will gel in the container; flip the container on a flat surface at room temperature; Allow the gel to cool and subsequently melt to form a sediment on the surface. The melting time is measured from the beginning of the cooling time (removal of boiling water) until a clarified sediment is formed. The methylcelluloses of the present invention, are useful in the same applications where conventional methylcelluloses are commonly used, as well as in additional applications where conventional methylcelluloses are not normally effective. The methylcelluloses of the present invention are particularly useful in food compositions and pharmaceutical capsules. Methyl celluloses having viscosity of up to about 1,000,000 centipoise (cP) at 2% by weight in aqueous solution at a temperature of 20 ° C, can be prepared according to the present invention. Preferred methylcelluloses can have viscosities from about 1 to about 600,000 cP (2% solution at a temperature of 20 ° C). The most preferred methylcelluloses can have viscosities from about 1 to about 100,000 cP (2% solution at a temperature of 20 ° C). For the purposes of the present specification, all viscosities of aqueous solutions are determined by means of the Ubbelohde tube in accordance with ASTM D1347-72 and D2363-79 (unless otherwise specified). Methylcelluloses that can be produced in accordance with the present invention, include but are not limited to, hydroxyethylmethylcellulose ("HEMC"), hydroxypropylmethylcellulose ("H PMC"), hydroxybutylmethylcellulose ("HBMC"), methyl ethyl cellulose ("M EC") and carboxymethylmethylcellulose ("CM MC"). Preferred HPMCs of the present invention will have a hydroxypropyl substitution of from about 1 to about 32%, more preferably from about 1 to about 14%, and most preferably from about 3 to about 12%. Preferred methylcelluloses for use in food compositions will have a substitution content without methoxy or a level of about 5% less, more preferably about 1% less, and even more preferably about 0.2% or less. The most preferred methylcelluloses for use in food compositions will be substantially free of substitution content without methoxy. For the purposes of the present specification, all substitutions and methoxyls are expressed as a percentage by weight based on the weight of the methyl cellulose (unless otherwise specified). The methylcelluloses of the present invention, which are useful in food compositions generally have a methoxyl substitution of about 21 to about 42% by weight based on the weight of the methylcellulose. For purposes of the present specification, all methoxyl substitutions are expressed as a percentage by weight based on the weight of the methylcellulose (unless otherwise specified). For the purposes of the present specification, all methoxyl substitution is determined in accordance with ASTM D2363-72 (unless otherwise specified). Preferred methylcelluloses (for purposes of use in food compositions) have a methoxyl substitution of at least about 25%. The most preferred methyl celluloses have a methoxyl substitution of at least about 29%. Preferred methylcelluloses of the present invention (for the purposes of being used in food compositions), have a methoxyl substitution of less than about 35%. The most preferred methyl celluloses have a methoxyl substitution of less than about 32%. The methylcelluloses of the present invention are produced by means of a new process. It is well known in the art that alkylate cellulose produces ethers (such as methyl cellulose). In conventional processes, the cellulose pulp is completely alkalized with sodium hydroxide, and etherified (ie, methylated) with a methylating agent (usually methyl chloride) in a single step. The degree to which cellulose is methylated is referred to as the percentage of methoxy substitution. This process and the underlying chemistry, have been well known in the art for a long time. Contrary to conventional processes for producing methylcellulose, the methylcelluloses of the present invention are produced through a new process that metilates the cellulose pulp into two or more separate steps. According to the present invention, the cellulose pulp is partially alkalized with alkali hydroxide, and partially methylated with a methylating agent (preferably methyl chloro) in a first step. While the present invention should not be limited to any particular theory it is considered that sites methylated in cellulose, after the first stage, are more selective for methylation in subsequent steps. That is, methylation is more likely to occur in subsequent stages near sites that were methylated in the first stage, resulting in a less uniform distribution of methylated sites in the cell, than occurs in methylcelluloses. conventional This less uniform distribution can be referred to as a "lock" substitution. The partially methylated cellulose produced in the first stage is additionally alkalized and additionally etherified with additional alkali metal hydroxide and methyl chloride to a desired level of heat in the subsequent step (s). Preferably, the methylating agent used in subsequent steps is introduced through continuous addition or increasing addition under reaction conditions sufficient to produce the desired level of methoxyl substitution. The cellulose used in the production of methylcelluloses of the present invention is usually cellulose pulp purchased from wood or cotton. The pulp is preferably provided in a powder or in the form of chips. The wooden chair is the preferred one. The alkylation of the cellulose pulp is carried out in a stepwise manner. A "step" refers to a reaction sequence in which an alkalization reaction and a methylation reaction (or substitution) take place. A step effectively increases the level of methoxyl substitution of the cellulose pulp or partially methylated cellulose. Optionally, other types of etherification can be performed, such as hydroxypropyl substitution, together with or in addition to the methoxy substitution. According to the present invention, the cellulose pulp is alkalized in two or more stages in one or more reactors with an aqueous alkali, preferably aqueous sodium hydroxide, the pulp can be alkalized with alkaline hydroxide by means known in the art. , such as the stepwise process in a bath or stirred tank containing aqueous alkali or aqueous alkali sprayed directly on the dried pulp. The reaction time varies according to the concentration, temperature and retention time of the hydroxide. The aqueous alkali is preferably used at an alkaline hydroxide content of about 30 to about 70% by weight based on the weight of the water. The alkalization temperature preferably ranges from about 30 ° C to about 110 ° C, and most preferably from about 30 ° C to about 90 ° C. The swelling and uniform alkali distribution in the pulp can be controlled by mixing and shaking. The range of aqueous alkali addition can be governed by the cooling capacity of the reactor during the exothermic alkalization reaction. The range of aqueous alkali addition is not critical to the present invention. If desired, an organic solvent such as dimethyl ether, in the form of a diluent and a cooler, can be added to the reactor. If desired, the space of the reactor head or reactors can be evacuated or purged with an inert gas, such as nitrogen, to control the oxygen catalyzed depolymerization of the alkali cellulose. In accordance with the present invention, the alkalized cellulose pulp is etherified (ie, methylated) in two or more stages, in one or more reactors to form methylcellulose. The reaction time of the etherification will depend on the concentration, or pressure, temperature, retention time and control capacity of the exothermic reaction. The preferred etherification agent is a methylating agent, such as methyl chloride or dimethyl sulfate. Methyl chloride is preferred. The methylating agent can be added through the addition of a batch filler, continuous addition or addition in increments in one or more steps. Preferably, the methylating agent is added through continuous addition or addition in increments in at least one stage after the first, preferably in the second stage. In the "batch addition," it means the addition substantially without a pause in a relatively short period of time. "Continuous addition" means the addition substantially without pause for a longer period of time. "Incremental addition" means the periodic addition of smaller or independent quantities over a longer period of time. The alkali hydroxide and the methylating agent can be added to the reactor at the same time, although they are preferably added sequentially with the alkali hydroxide being added first and the methylating agent then added. A two step process is preferred for making the methyl celluloses of the present invention. In one step, the aqueous alkaline hydroxide and the methylating agent are reacted with cellulose pulp to form a methylcellulose from a first level of methoxyl substitution. Each alkali hydroxide and the methylating agent can be added in one step, by means of a batch addition, continuous addition or incremental addition. The range of addition is not critical. The reaction temperature in the first stage is preferably controlled, so that a generally uniform contact and reaction may occur between the alkali hydroxide, the methylating agent and the cellulose pulp. In the second step, additional amounts of the aqueous alkali metal hydroxide and the methylating agent are reacted with the partially methylated cellulose, to form a methyl cellulose with a second level (that is, the desired level) of methoxy substitution. The alkali hydroxide and the methylating agent can be added in the second stage by means of a batch addition, continuous addition or incremental addition. The range of hydroxide addition in the second stage is not critical. The methylating agent is added in the second stage at a mass reaction temperature of about 65 ° C to about 120 ° C for an additional time of 15 minutes or more; preferably from about 75 ° C to about 100 ° C for 20 minutes or more; and most preferably from about 80 ° C to about 90 ° C for 25 minutes or more. Although the methylating agent can be added continuously or in increments during any extended period of time in the second, it is preferable for reasons of economy of time to carry out the addition in about 120 m inutes or less, more preferably in about 60 m inutes or less and most preferably in about 25 to about 45 minutes. After the addition of the methylating agent in the second stage, the etherification can be carried out at any temperature at which the reaction can proceed, although for reasons of economy of time it is preferred to carry it out at a temperature of about 65 ° C to about 120 ° C and more preferably from about 80 ° C to about 90 ° C. The temperature inside the reactor can be determined by any means known in the art. The temperature determining means include using steam temperature control and using a thermocouple with protuberances in the content (mass of cellulose pulp / methyl cellulose) of the reactor. In a preferred two-stage process, both steps are carried out in the same reactor. Preferably, from about 20% to about 80% of the total methoxyl substitution is carried out in the first step and from about 80% to about 20% in the second step. More preferably, from about 30 to about 70% of the total methoxyl substitution is carried out in the first step, and from about 70 to about 30% in the second step. Most preferably, from about 40 to about 60% of the total methoxyl substitution is carried out in the first stage and from about 60 to about 40% in the second stage. In Table 1, some modalities of the two-stage processes are described.

A three-step process is also useful for making the methyl cellulose of the present invention. The first step is carried out in a manner similar to that of the first stage of the two-step process described above. Either or both of the second and third steps are carried out in the same manner as the second step in the two-step process described above (the methylation agent is preferably added continuously or in increments over a period of time) . In a preferred three stage process, from about 20 to about 60% of the total methoxyl substitution is carried out in each of the first and second stages, and from about 5 to about 30% in the third stage. stage. In Table 1, some modalities of the three-stage processes are described. It is also possible to have processes with four or more stages. The first stage of said process could be carried out in the same way as the first stage in the two-stage process described above. One or more of the subsequent steps could be carried out in the same manner as the second step in the two-step process described above (the methylating agent is preferably added continuously or increments over a period of time). ro rO or «VI n Table 1 Some Useful Modalities of the Process of the Present Invention C? Methyl celluloses such as HEMC, HPMC, HBMC, M EC and CM MC can be prepared by reacting the cellulose pulp or a methyl cellulose with another etherification agent, in addition to the methylating agent (also an etherification agent). Useful etherification agents include ethyl chloride, ethylene oxide, propylene oxide, and butylene oxide. The other etherification agent can be reacted at any stage before, during or after the reaction through the methylation agent under conditions of sufficient processes to effect the desired reaction. The other etherification agent can be added to the reactor through batch addition, continuous addition or incremental addition. Preferably, the other etherification agent is reacted in the first stage. Preferably, the other etherification agent is reacted before or together with the methylation agent. The methylating agent and any other etherification agent can be added to a reactor in a liquid or vapor form. The liquid form is highly preferred. The reactor is preferably maintained at pressures, such that the agents predominantly remain in the liquid phase. After etherification, the methylcellulose is washed to remove salt and other reaction byproducts. Any solvent in which the salt is soluble may be employed, although water is preferred. The methylcellulose can be washed in the reactor, although it is preferably washed in a separate scrubber located in the downstream of the reactor. Before and after washing, the methylcellulose can be detached by exposure to steam, to reduce the residual organic content. The methylcellulose is dried to obtain a reduced moisture and a volatile content preferably from about 0.5 to about 10.0 wt% of water, and more preferably from about 0.8 to about 5.0 wt% of water and volatiles based on the weight of the methyl cellulose . The moisture and the reduced volatile content make it possible for the methylcellulose to be ground into a particulate form. The methylcellulose is preferably dried at a temperature from about 40 ° C to about 130 ° C. Useful dryers include tray dryers, fluid bed dryers, instant dryers, agitation dryers, and tube dryers. The methylcellulose is milled to obtain particulates of desired size. If desired, drying and grinding can be carried out simultaneously. The grinding can be carried out by any method known in the art, such as ball grinding, impact pulverizer, blade grinder and grinder with air sweeping impact. The methyl cellulose of the present invention is useful in a variety of food compositions. Examples of food compositions include vegetables; meat and soy pasta; sea food reformed; refurbished cheese food; soups of cream, greyvis and seasonings; salad dressings; Mayonnaise; onion rings; jams; jellies and syrups; fillings for cakes; potato products such as potato chips and extruded, even to overflow fried foods, cakes / waffles and cakes; pet food; drinks; frozen desserts; cultured dairy products such as ice cream, fresh cheese, yogurt, cheeses and creams; bitumen and cake frostings, gelatinous ingredients for cake coverings; fermented and deferred baked goods. In the formation of food compositions, methylcellulose is usually mixed with food products during the process and formation of the compositions. The food products may be in any known form, such as a particle form or unitary form. In the following publications are excellent teachings for the preparation of food compositions with methylcellulose: M ETHOCEL® Product Publications (trademark of The Dow Chemical Company): Premium M ETHOCEL Food Grades, (METHOCEL Premium Food Gums), Forms Nos. 192-1037-87, 192-1047-87, 192-1046-87, 192-1051-87, 192-1050-87, 192-1049-87, 192-1053-87, 1 92-982-87, 1 92-979-87, 192-985-87, 1 92-104-87, 192-1048-87, 192-987-87, 192-986-87, 192-989-87, 1 92-988-87, 192-984-87, 192-983-87, 192-981 -87, 192-991 -87, 192-980-87, 192-990-87, and 192-1052-87 (all published in 1987); Selection of Food Grades M ETHOCEL (Selecting M ETHOCEL Food Gums), Form No. 192-855-1281 R (published in 1981); M ETHOCEL Food Grains in Non-Dairy Gelatinous Covers (METHOCEL Food Gums I n Non-Dairy Whipped Topping), Form No. 192-877-482 (published in 1982); Food Grade M ETHOCEL in Fried Foods (M ETHOCEL Food Gums In Fried Foods), Forms Nos. 192-875-482 and 192-881 -482 (all published in 1982); Food Grade M ETHOCEL in Dressings and Sauces for Salads (M ETHOCEL Food Gums In Salad Dressings and Sauces), Forms Nos. 192-876-482, 192- 880-482 and 192-905-1282 (all published in 1982); and M ETHOCEL Food Grains in Baking Products (M ETHOCEL Food Gums I n Bakery Products), Forms Nos. 192-874-482 and 192-878-482 (all published in 1982). All teachings of the above publications are incorporated herein by reference. Methylcelluloses particularly useful in food compositions are methylcelluloses that have little or no substitution of methoxy and hydroxypropylmethylcellulose. Methylcelluloses are normally used in food compositions at levels of from about 0.01 to about 5% based on the total weight of the food composition. Methyl celluloses are useful in other applications, such as products for construction, industrial products, agricultural products, personal care products, household products and pharmaceutical products. Useful pharmaceutical applications include capsules, encapsulations, coatings of tablets and excipients for drugs and drugs. Useful excipient functions include sustained release and scheduled release tablets. Useful construction applications include drywall bonding compounds, mortars, cement grouts, cement plasters, spray plasters, cement stucco, waste such as pastes, and wall / ceiling texturizers. Useful industrial applications include linkers and processing aids for belt condition, extrusion and molding, and injection ceramics. Useful agricultural applications include spray tackifiers, suspension / dispersion aids for pesticides, herbicides and fertilizer dusts. Useful personal and household care products include shampoos, lotions, creams and cleaning products. The methylcelluloses of the present invention are particularly useful in pharmaceutical capsule compositions. Capsules formed from the methylcelluloses of the present invention may exhibit substantially less distortion after drying than capsules formed from conventional celluloses. Particularly useful methylcelluloses are methylcelluloses that have little or no substitution of low molecular weight methoxy and hydroxypropylmethylcellulose., for example from about 3 to about 100 cP and preferably from about 3 to about 15 cP in a 2% aqueous solution. The low molecular weight methylcelluloses can be prepared directly from the processes described above, they can be prepared from high molecular weight methylcelluloses by means of acid catalyzed depolymerization. Useful acids include hydrogen chloride anhydride and hydrochloric acid. After depolymerization to the desired degree, the acid is neutralized and depolymerization is capped by contact with a base such as sodium bicarbonate. Useful teachings related to the manufacture of low molecular weight methylcellulose are described in US Patent No. 09 / 203,324, filed December 1, 1998, which is incorporated herein by reference. The methylcellulose capsules are usually manufactured by bathing hot needles in an aqueous solution of cold methylcellulose coating, or by bathing cold needles in an aqueous solution of hot methylcellulose coating. The gel solutions on needles and water are evaporated during the drying step to form thin film layers of dry cellulose around the needles. The thin films take the form of caps and bodies, which are removed from the needles and adjusted to form capsules. Processes for making capsules are described in US Pat. Nos. 3,617,558; 4,001,211; 4,917,885 and 5,756,036, which are incorporated herein by reference. When drying takes place unevenly during the manufacture of pharmaceutical capsules with conventional methylcellulose, the caps and bodies can sometimes become distorted and difficult to fit or assemble in the capsules. The caps and bodies formed from the methylcelluloses of the present invention can better resist said distortion due to their improved gel strength. The following are examples of the present invention. Unless stated otherwise, all percentages, parts and proportions are by weight. EXAMPLES Example 1 A methyl cellulose of the present invention was made, according to a process thereof. Pulp of finely ground cellulose wood was loaded into a covered stirred reactor. The reactor was evacuated and purged with nitrogen to remove the oxygen and later it was evacuated again. The reactor was used in two stages. In the first stage, 50% sodium hydroxide in water was sprayed by weight on the cellulose in a weight ratio of 0.45 / 1 .0 NaOH / cellulose, and the temperature was adjusted to 40 ° C (starting temperature). After stirring the NaOH / cellulose for about 10 to 20 minutes, a mixture of dimethyl ether and methyl chloride was added to the reactor with additional methyl chloride, so that the weight ratio of methyl chloride / cellulose was approximately 0.64 / 1 .0. Subsequently, the contents of the reactor were heated from a temperature of 40 ° C to 80 ° C for the next 40 minutes. After reaching a temperature of 80 ° C (cooking temperature), the first reaction stage was allowed to proceed for another 30 minutes (cooking time). The second step was carried out by adding the rest of the sodium hydroxide and methyl chloride and allowing the additional reaction. A second amount of 50% NaOH in water by weight was added for 10 minutes, in a weight ratio of 0.65 / 1 .0 NaOH / cellulose (the cellulose is actually partially etherified at this point in time). A second amount of methyl chloride was added for about 35 minutes to a weight ratio level of 0.90 / 1 .0 methyl chloride / cellulose. The reaction was continued at a temperature of 80 ° C for an additional 30 minutes (cooking time) to complete the etherification. Table 2 illustrates the process information and data pertaining to alkalization and etherification. After the reaction, the reactor was ventilated and cooled to a temperature of 50 ° C. The content of the reactor was removed and transferred to a tank containing hot water, to form a paste which is agitated substantially for 15 minutes. This paste was pumped from the hot tank to a filter, where the water was extracted and washed with hot water to remove the salt and organic byproducts. Subsequently, the wet methylcellulose was transferred to a dryer where the moisture content and volatiles were reduced to 1 to 4% by weight based on the weight of the methylcellulose. Subsequently, the methylcellulose was milled until obtaining a particle size of approximately 40 Maya (420 m icrometers). The methylcellulose product was analyzed, and it was found to contain 31.8% methoxyl substitution (a degree of methoxyl substitution of 1.96). It exhibited a viscosity of 17,000 centipoise (cP) at 2% by weight in aqueous solution by weight, a gelation temperature of (Tflβ?) Of 1 05 ° F - 108 ° F (40.6 ° C - 42.2 ° C), and an elastic modulus (G ') of 5445 Pascais for a 1.5% by weight of aqueous solution, and a melting time of 35 minutes. The properties of the product are set forth in Table 3. These physical properties are more desirable than those of conventional methylcelluloses of substitution level and similar viscosity. Such conventional methylcelluloses normally exhibit a Tge? from about 52 ° -59 ° C to 1.5 g of aqueous solution and G 'of 800-2000 Pascais to a 1.5% aqueous solution. Thus, the methyl cellulose of the present invention has the advantages of a gelation temperature both significantly higher G 'and significantly lower compared to a conventional methylcellulose of similar degree of substitution. In the various examples described in the present invention, G 'was measured for 1.5% by weight of aqueous solution in a Bohlin VOR rheometer (Bohlin Corp.) with a sledge and toothed cup system C25. Examples 1A-1D The samples of the methyl cellulose product of Example 1 were depolymerized by reaction with anhydrous hydrogen chloride for a variety of time durations followed by neutralization with sodium bicarbonate. After depolymerization, a sample exhibits a viscosity of 614 cP (2% solution), a G 'of 2250 Pascais and a melting time of 20 minutes. After another depolymerization, one sample exhibited a viscosity of 219 cP, and G 'of 1400, a Tge? of 108 ° F (42 ° C), and a casting time of 40 minutes. After another depolymerization, one sample exhibited a viscosity of 81 cP, a G 'of 1390 Pascais, a Tgei of 103 ° F (39 ° C) and a melting time of 19 minutes. After another depolymerization, a sample exhibited a viscosity of 66 cP, a G 'of 1680 Pascais and a melting time of 25 minutes. The properties of the product are set forth in Table 4. Example 2 Another methylcellulose of the present invention was made according to a process thereof. The process is as in Example 1, except where otherwise indicated in Table 2. The methylcellulose product had a methoxyl substitution of 31.3% and exhibited a viscosity of 26,000 cP in 2% by weight aqueous solution , a Tge? of 34.4 ° C, a G 'of 3740 Pascais and a casting time greater than 50. These physical properties compare very favorably with those of a conventional methylcellulose of similar substitution level and viscosity. The properties of the product are set forth in Table 3. Examples 2A-2B The samples of the final methylcellulose product of Example 2 were depolymerized by reaction with anhydrous hydrogen chloride for a variety of time durations followed by neutralization with sodium bicarbonate. . After depolymerization, one sample exhibited a viscosity of 357 cP (2% solution), a G 'of 1080 Pascais, and a casting time greater than 50 minutes. After another depolymerization, one sample exhibited a viscosity of 29 cP, a G 'of 569 Pascais, a Tge? of 87 ° F (31 ° C), and a casting time of 30 minutes. The properties of the product are set forth in Table 4. Example 3 Another methylcellulose of the present invention was made, according to the process thereof. The process is as in Example 1, except where otherwise indicated in Table 2. The methylcellulose product had a 29.9% methoxyl substitution and exhibited a viscosity of 30,000 cP (2% solution), a Tge , of 89 ° F (31 .7 ° C), and a G 'of 3200 Pascais, a time greater than 50 minutes. The properties of the product are set forth in Table 3. Example 4 Another methyl cellulose of the present invention was prepared according to the process thereof, the process is as in Example 1 except where otherwise indicated in the table 2. The methylcellulose product had a 32.9% methoxyl substitution and exhibited a viscosity of 1 1, 000 cP (2% solution), a Tgei of 122 ° F (50 ° C), a G 'of 3180 Pascais, and a foundry time of 17 m inutes. The properties of the product are established in Table 3. Example 5 Another methylcellulose of the present invention was made with the same process. The process is as in Example 1, except where otherwise indicated in Table 2. The methylcellulose product had a 32.7% methoxyl substitution and exhibited a viscosity of 2600 cP (2% solution), a Tgei of 1 18 ° F (48 ° C), a G 'of 1460 Pascais and a melting time of 20 m inutes. The properties of the product are set forth in Table 3. Example 6 Another methyl cellulose of the present invention was made, with the process of it. The process is as in Example 1, except where otherwise indicated in Table 2. The methylcellulose product had a 26.9% methoxyl substitution and exhibited a viscosity of 330 cP in 2% by weight of aqueous solution , a Tge? of 128 ° F (554 ° C), a G 'of 1470 Pascais and a casting time of 8 minutes. The properties of the product are established in Table 3. Example 7 Another methylcellulose of the present invention was made with the process thereof. The process is as in Example 1, except that it has an additional stage (third). The information of the process is established in table 5.

The methylcellulose product had a 35.4% methoxyl substitution and exhibited a viscosity of 461,000 cP (2% solution), a Tgei of 45 ° C and a G 'of 6900 Pascais and was stable for melting at room temperature. Does this methylcellulose product have the advantages of a Tge? significantly higher G 'and significantly lower, compared to conventional methylcelluloses of similar methoxyl substitution level and viscosity. The properties of the product and composition are set forth in Table 6. Example 8 Another methylcellulose of the present invention was made with the same process. The process is as in example 1, except that it has an additional stage (third). The process information is set forth in Table 5. The methylcellulose product had 36.1% methoxyl substitution and exhibited a viscosity of 26,000 cP (2% solution), a Tge? of 1 13 ° F (45 ° C), a G 'of 7990 Pascais, and was stable for casting at room temperature. This methylcellulose product has the advantages of a significantly higher gelation temperature G 'and significantly lower, compared with conventional methylcelluloses of similar methoxyl substitution level and viscosity. The properties of the product and composition are set out in Table 6. Example 9 Another methylcellulose of the present invention was made with the same process. The process is as in example 1, except that it has an additional step (third). The information of the process is established in table 5.

The methylcellulose product had a 34.9% methoxyl substitution and exhibited a viscosity of 25,000 cP (2% solution), a Tgei of 95 ° F (35 ° C), and a G 'of 7565 Pascais and was stable for casting at room temperature. Does this methylcellulose product have the advantages of a Tge? significantly higher G 'and significantly lower, compared with conventional methylcelluloses of similar methoxyl substitution level and viscosity. The product properties and compositions are set forth in Table 6. A number of methyl cellulose moieties were generated using a conventional process known in the art. The process properties of these samples are set forth in Table 7. The properties of gel strength and viscosity of the samples of the prior art, which are set out in Table 7, were plotted together with the properties of gel strength. and viscosity of Examples 1, 1 A, 1 B, 1 C, 1 D and Examples 2, 2A and 2B as set forth in Tables 3 and 4. The corresponding graph is shown in Figure 1. The relationship between gel resistance (expressed in logarithmic scale) and viscosity (logarithmic scale) is approximately linear. The lines were drawn for each group of data using a better adjustment algorithm. The equations that approximate each line are indicated in the graph. The graph in Figure 1 demonstrates that the gel resistance of the methylcelluloses of the present invention having methoxyl substitution of between about 29% and 32% is greater than about 223 xv 273. It will be understood that this strength relationship to the viscosity gel, it is an approximation and the methylcelluloses of the present invention may fall slightly below this approximation. For example, the data in Table 3 indicates that Example 3 falls slightly below the line representing Examples 2, 2A and 2B, although it is well above the line representing the prior art. Although the embodiments of the process and compositions of the present invention have been shown with respect to specific details, it will be appreciated that the present invention may be modified insofar as it remains within the scope of the teachings and new principles established therein. .

NO OR in co o rO Ul O en en Table 3 Product Properties and Commendation of the Eem from 1 to 6 G'- Elastic modulus in Rascáis in 1.5% aqueous solution; corresponds to resistance to the gel. Viscosity - viscosity in 2% aqueous solution in centipoise (cP)? MeO% - percentage of methoxyl substitution based on the weight of methylcellulose. MeODS- of methoxyl substitution Tgel- gelation temperature Table 4 Eem Product Properties of 1A-1D Eem 2A-2B Table 5 Information Process for Examples 7-9 Table 6 Product Properties and Compositions of Examples 7-9 G 'Elastic modulus in Pascais in 1 5% aqueous solution Viscosity viscosity of 2% aqueous solution in centipoise (cP) eO percentage of methoxyl substitution based on the weight of methyl cellulose Casting Time (minutes) degree of methoxyl substitution Percentage of methoxyl substitution G '= Dynamic Elastic Module in a Boiling Rheometer 1.5% aq. Back to Melt in time (minutes) of the Gel Solution 1.5% Thermal Gelation Temperature, 1.5% solution

Claims (10)

1. REVIVAL NAME IS 1. A process for making methylcellulose having a level of methoxyl substitution of 21 to 42% by weight, which comprises the steps of: a) reacting a pulp of cellulose with a first quantity of aqueous alkaline hydroxide and a first quantity of agent of methylation under reaction conditions sufficient to methylate the cellulose pulp to a first level of methoxyl substitution, which is 20% or more of the total level of methoxyl substitution; and b) reacting the methycellulose of the first level of methoxy substitution with a second amount of aqueous alkaline hydroxide to alkalize it to a second level of alkalization, and irrigate the methyl cellulose of the second level of alkalization in continuously or in increments, a second quantity of a methylating agent under reaction conditions sufficient to methylate it to a second level of methoxy substitution which is 40% more than the total level of methoxy substitution.
2. 2. The process according to claim 1, wherein the second amount of methylating agent is added at a temperature of 65 ° C to 120 ° C for 15 minutes or more.
3. 3. The process according to claim 1 or 2, wherein the methylation reaction is carried out at a temperature of 65 ° C to 120 ° C.
4. 4. The process of conformity with any of claims 1 to 3, wherein the process is a two-step process, from 20 to 80% of the total level of methoxyl substitution is carried out in the first stage , and from 80 to 20% of the total level of substitution of methoxyl and is carried out in the next stage.
5. 5. The process of conformity with claim 4, wherein the process is a two-step process, from 40 to 60% of the total level of methoxyl substitution is carried out in the first stage, and from 60 to 40% of the The total level of methoxyl substitution is carried out in the second stage.
6. 6. The process of conformity with any of claims 1 to 3, wherein the process is a three-stage process, wherein the process comprises the additional steps of: contacting the methyl cellulose of the second level of substitution of methoxyl with a third amount of aqueous alkaline hydroxide, to alkalize it to a third level of alkalization; and contacting the methylcellulose of the third level of alkalization with a third amount of methylating agent in sufficient reaction conditions to form a methyl cellulose having a level of methoxy substitution of 21 to 42% by weight.
7. 7. The process according to claim 6, wherein from 20 to 60% of the total level of methoxyl substitution is carried out in each of the first and second stages and from 5 to 30% in the third stage.
8. 8. The process according to claim 1, wherein the contact with the cellulose pulp or the methylcellulose is carried out in the first or in the second step with an amount of propylene oxide under sufficient reaction conditions. to form a methylcellulose with hydroxypropyl substitution.
9. 9. The process according to claim 1, wherein the contact with the cellulose pulp or the methylcellulose is carried out in the first or second stage with an amount of butylene oxide, under sufficient reaction conditions to form a methylcellulose with hydroxymethyl substitution. The process according to claim 1, wherein the contact with the cellulose pulp or the methylcellulose is carried out in the first or second step with an amount of ethylene oxide, under reaction conditions sufficient to form a methylcellulose with hydroxyethyl substitution. eleven . The process according to claim 1, wherein the contact with the cellulose pulp or methylcellulose is carried out in the first or second step, with an amount of ethyl chloride under sufficient reaction conditions to form a methylcellulose with substitution of ethoxy 12. The process according to any of claims 1 to 1, wherein the methylcellulose has a methoxyl substitution of 25 to 35% by weight. 13. The process according to any of claims 1 to 12, wherein the process further comprises; c) bathing a needle in a methylcellulose solution of the total level of methoxyl substitution; d) let the solution gel on the needles; e) drying the solution to form dry and thin layers of methylcellulose in the form of layers and bodies that have the ability to be adjusted to form pharmaceutical capsules; and f) remove the caps and bodies on the needles. 14. A methyl cellulose made according to the process according to any of claims 1 to 13. 15. A methyl cellulose having a methoxyl substitution of 21 to 42% by weight, based on the weight of the methyl cellulose, and a gel strength greater than 223 x (v0 273), where v represents the viscosity of methylcellulose for 2% aqueous solution at a temperature of 20 ° C. 16. The methyl cellulose according to claim 15, which has a methoxyl substitution of 29 to 32% by weight. 17. The methyl cellulose according to any of claims 14 to 16, wherein the gel strength is greater than 490 x (v. 241). 18. Methylcellulose according to any of claims 14 to 17, wherein the methylcellulose has a viscosity of 1 to 600,000 centipoise at 2% by weight in aqueous solution at a temperature of 20 ° C. 19. Methylcellulose according to any of claims 14 to 18, wherein the methylcellulose has a non-methoxyl substitution of 1% by weight based on the weight of the methylcellulose. The methyl cellulose according to any of claims 14 to 19, wherein the methyl cellulose is in the form of a pharmaceutical capsule or in the form of an excipient for a pharmaceutical tablet. twenty-one . The methyl cellulose according to any of claims 14 to 19, wherein the methyl cellulose is in the form of any of the following: a pharmaceutical encapsulation, a capsule, a tablet coating, or excipient; a composite of bonding tape for dry wall; a mortar; a cement slurry; a cement plaster; a plaster by dew; a cement coating; an adhesive; a pasta; a wall / ceiling texturizer; a bonding or processing assistant for ribbon casting, extrusion forming or injection molding; an adherent agricultural spray; a suspension / dispersion aid for pesticides, herbicides or fertilizer powders; a shampoo; a lotion; a cleaner; or a ceramic. 22. A food composition comprising a methyl cellulose according to any of claims 14 to 19. The food composition according to claim 22, wherein the food composition is selected from the group consisting of vegetarian patties, of meat and soybeans; refurbished sea foods; Reformed cheese sticks; cream soups; greyvis and dressings; salad dressings; Mayonnaise; onion rings; jams, jellies and syrups; stuffing for cakes; products formed from potatoes such as potato chips and extruded potatoes; pasta to overflow fried foods, cakes / waffles, and cakes; pet food; drinks, frozen desserts; cultured dairy products such as ice cream, fresh cheese, yogurt, cheeses and creams; glaze and covers for cake, fermented and unfermented baked goods; and gelatinous covers for cake. 24. The food composition according to claim 22 or 23, wherein the food composition comprises 0.01 to 5% by weight of methyl cellulose based on the total weight of the composition.