Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/18—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00 of old paper as in books, documents, e.g. restoring

Definitions

• This invention relates to the preservation of objects that contain cellulose-type materials, in particular, to a product, in the form of a solution, for de-acidification of cellulose-type materials composed of carbonated magnesium di-n-propylate, n-propanol and a hydrofluorocarbon diluent.
• the North American patent US-A-3.676.182 (R.D. Smith, 11th July 1972) relates to a procedure for non-aqueous de-acidification of paper using magnesium methoxide, dissolved in methanol to a concentration lying between 5 % and 11 %, as the de-acidifying agent.
• the resulting solution can be diluted with a chlorofluorocarbon (CFC) diluent, such as trichlorofluoromethane or dichlorodifluoromethane, until a liquid is formed, under pressure, that contains between 1 % and 2 % of the de-acidifying agent.
• CFC chlorofluorocarbon
• the CFC compound quickly evaporates from paper impregnated with the de-acidifying solution containing methanol, thus minimizing the solvent effect of methanol on certain inks.
• the books and papers can be treated by immersion in the de-acidifying solution, or the solution can be applied with a brush or using a spray. Nevertheless, this method is not free from drawbacks as the magnesium methoxide is extremely sensitive to water. So much so that even traces of moisture lead to immediate hydrolysis forming a gelatinous precipitate of magnesium hydroxide. This is insoluble in water and many organic solvents.
• the Canadian patent CA-A-1.147.510 (Smith, R.D., 7th of June 1983) discloses a method for the production of methoxymagnesium methylcarbonate.
• Metallic magnesium is allowed to completely react with methanol to form magnesium methoxide. This is then re-dissolved in methanol saturated with carbon dioxide forming a methoxymagnesium methycarbonate solution.
• This solution is diluted with trichlorotrifluoro-ethane or with dichlorodifluoromethane.
• the diluted solution is sprayed onto the paper to be de-acidified.
• the paper can be submerged in the same solution, with the liquid state being maintained under pressure.
• a de-acidifying agent preferable an alkoxide of magnesium carbonate
• a CFC diluent preferably trichlorotrifluoroethane
• a propellant gas preferably dichlorodifluoromethane. Additional pressurization and propulsion can be achieved using an inert gas such as nitrogen.
• the carbonated magnesium alkoxide such as methoxymagnesium methylcarbonate or ethoxymagnesium ethylcarbonate, is produced by dissolving the corresponding magnesium alkoxide in alcohol in the presence of carbon dioxide.
• the Canadian patent CA-A-2.142.195 discloses and claims a product for de-acidification of cellulose-type materials which consists of a de-acidifying reagent, such as methoxymagnesium methylcarbonate or ethoxymagnesium ethylcarbonate, a solvent such as methanol or ethanol, and a hydrochlorofluorocarbon diluent (HCFC) or hydrofluorocarbon (HFC).
• HCFC hydrochlorofluorocarbon diluent
• HFC hydrofluorocarbon
• HCFCs and HFCs as a substitute for CFCs substantially reduces the number of chlorine radicals that can be liberated in the stratosphere on exposure to cosmic radiation, thus reducing the potential for ozone destruction.
• the presence of hydrogen means that the compound is more reactive, such that it tends to decompose more easily before reaching the stratosphere.
• the rate of decomposition of HCFCs and HFCs is higher than that of the CFCs, whose lifetime is quoted at being between 60 and 100 years.
• the object of the present invention is to find a new product for the non-aqueous de-acidification of cellulose-type materials, thus providing an addition to the arsenal of means available for combating acidification of cellulose-type materials.
• an object of this invention consists of a product, in the form of a solution, for the non-aqueous de-acidification of cellulose-type materials which comprises carbonated magnesium di-n-propylate, n-propanol and an HFC diluent.
• An additional object of this invention consists of a procedure for production of said product for the de-acidification of cellulose-type material.
• Another additional object of this invention consists of a method for de-acidification of cellulose-type material which comprises use of the aforementioned product.
• the present invention provides a product for de-acidification of cellulose-type material, hereinafter denominated the product of the invention, characterized in that it is presented in the form of a solution and is comprised of:
• Carbonated magnesium di-n-propylate is a white solid, with the formula (CH 3 CH 2 CH 2 O) 2 MgOCO, soluble in anhydrous n-propanol and in medium-polarity solvents, such as HFC 227 and HFC 134a, whose polarities are 0.8 Debyes (D).
• organic solvents of medium polarity includes solvents with a dipole moment ( ⁇ ) less than water [ ⁇ : 1.8 D], for example, toluene [ ⁇ : 0.40 D] and n-propanol [ ⁇ : 1.5 D].
• Carbonated magnesium di-n-propylate has a dipole moment of 0.8 D and so, in general, it is soluble in any proportion in the HFC diluent used for producing the product of the invention.
• the dipole moment of this diluent is approximately 0.9 D.
• Carbonated magnesium di-n-propylate on coming into contact with moist air, reacts to give magnesium carbonate and magnesium hydroxide, and slowly releases n-propanol according to the reaction [1]: 2(CH 3 CH 2 CH 2 O) 2 MgOCO + 3H 2 O ⁇ Mg(OH) 2 + MgCO 3 + 4CH 3 CH 2 CH 2 OH
• Carbonated magnesium di-n-propylate reacts vigorously with mineral acids releasing carbon dioxide and n-propanol, forming soluble magnesium salts as indicated by reaction [2] : (CH 3 CH 2 CH 2 O) 2 MgOCO + 2 HCl ⁇ MgCl 2 + CO 2 + 2 CH 3 CH 2 CH 2 OH
• reaction [2] (CH 3 CH 2 CH 2 O) 2 MgOCO + 2 HCl ⁇ MgCl 2 + CO 2 + 2 CH 3 CH 2 CH 2 OH
• magnesium carbonate hydroxide a stable compound of the formula (MgCO 3 ) 4 .Mg(OH) 2 .5H 2 O, which, deposited among the paper fibres, acts as an alkaline reservoir protecting against acidic atmospheric contaminants and acids released in the paper during ageing.
• the trials carried out on papers treated and submitted to accelerated ageing have shown that treatment with the product of the invention [see Example 3] stabilizes the properties of the mechanical resistance of the paper, manifesting itself as a stabilization in the degree of whiteness.
• Carbonated magnesium di-n-propylate can be obtained from magnesium di-n-propylate by a procedure that comprises the stages of:
• Reaction of magnesium di-n-propylate with anhydrous carbon dioxide is an exothermic reaction, reaching temperatures of up to 45° C and the initial solid compound insoluble in n-propanol [magnesium di-n-propylate] is transformed into a soluble form consisting of carbonated magnesium di-n-propylate.
• the reaction is taken to have reached its conclusion when the temperature drops to room temperature.
• the dark solid insoluble particles are allowed to sediment out on the bottom of the recipient and to give a clear and transparent solution.
• the resulting solution is collected by conventional techniques, for example, by decantation or, preferably, by suction under vacuum, and transferred to recipients suitable for loading, dilution or dosing.
• the carbonated magnesium di-n-propylate obtained is purified, for example, by evaporation of part of the solvent (typically 20-30 %) under vacuum.
• the concentration of carbonated magnesium di-n-propylate in the alcoholic solution lies between 30 and 70 % (P/P), preferably between 45 and 50 % (P/P) of carbonated magnesium di-n-propylate, the rest consisting of n-propanol. It can be adjusted to the desired concentration by conventional methods, for example, by dilution with n-propanol or by elimination of excess solvent.
• Magnesium alkoxides can be obtained using known methods, for example, Metal Alkoxides, by Bradley, D.C., Mehrotra, R.C. and Gaur, D.P., Academic Press, London (1978), and the work of Thorns, H., Epple, M., Viebrock, H. and Reller, A., J. Mater. Chem. 5(4)589, (1995), where the synthesis of different magnesium alkoxides from alcohols of up to four carbon atoms is described.
• the suspension of magnesium di-n-propylate in n-propanol can be prepared by different procedures.
• One 5 of them comprises reacting magnesium metal with anhydrous n-propanol, in the presence of iodine, at the temperature corresponding to the boiling point of the mixture.
• Another procedure comprises reacting magnesium metal with anhydrous n-propanol in the presence of iodine at reflux temperature and the addition of toluene to form an azeotrope with n-propanol.
• the magnesium metal used in either Procedure A or B may in the form of a strip, in which case, it requires a suitable preparation (see Example 1.2).
• the suspension of magnesium di-n-propylate in n-propanol can be prepared by a procedure (Procedure C) which does not require the use of a strip of magnesium but rather magnesium in powder form, with a granulometric distribution between 50 and 150 ⁇ m.
• This procedure C therefore comprises of; (i) reacting magnesium in powder form, with a granulometric distribution between 50 and 150 ⁇ m, with anhydrous n-propanol in the presence of iodine, which acts as a catalyst. The mixture is gently heated until hydrogen begins to be released.
• the next step (ii) consists of cooling the reaction mixture to the temperature corresponding to the boiling point, with a view to controlling the reaction rate with gentle boiling until hydrogen is no longer given off and the last remaining particles of magnesium have disappeared. In this fashion a suspension of magnesium di-n-propylate in n-propanol is obtained.
• magnesium in the form of powder with the indicated granulometric distribution means that the reaction of magnesium with n-propanol in the presence of iodine is exothermic, and so the reaction medium should be cooled instead of additional energy being provided. This also allows the reaction time to be reduced [typically, the total reaction time for production of magnesium di-n-propylate is 4-5 hours].
• Carbonated magnesium di-n-propylate can be used in the production of a product, in the form of a solution, suitable for de-acidification of cellulose-type material along with n-propanol, and a diluent selected from HFC 134a and HFC 227.
• cellulose-type material refers to a material totally or partially composed of cellulose fibres, including paper of all classes, tissues and fabrics which contain cellulose fibres of vegetal origin, for example, those produced from wood, cotton, flax, jute, hemp and other plants.
• cellulose-type materials include books, documents, maps, works of art, articles elaborated with said materials, clothing, flags, etc.
• a solution of carbonated magnesium di-n-propylate and n-propanol is produced, in HFC diluent, at a concentration lying between 30 % and 70 % (W/V) for application by machine and of 3.5 % to 4.5 % (W/V) in said HFC diluent for application by sprays.
• said solution is of light chestnut colour and viscous.
• the concentrated solution of carbonated magnesium di-n-propylate is diluted to the desired concentration with a chemically inert and non-toxic diluent which allows the de-acidifying reagent to be carried inside the cellulose-type material.
• An HFC selected from HFC 134a and HFC 227 can be used as diluent.
• HFC 227 is preferable.
• HFC 227 has a boiling point of -17.3° C at normal pressure (101.3 kPa), a liquid density of 1.417 g/cm 3 at 20°C (399.3 kPa).
• HFC 227 has been marketed since 1991 as a substitute for R12 and R114 in sectors where these chemicals have been used as coolants.
• the company SOLVAY brought this product onto the market at the beginning of 1996 as, in September 1995, the European Commission for Pharmaceutical Products in Brussels (CPMP) established that HFC 227 was suitable for pharmaceutical inhalers.
• Dilution of the concentrated solution of carbonated magnesium di-n-propylate is carried out with the chosen HFC, preferably HFC 227, in pressurized containers, up to de-acidification reagent concentrations [carbonated magnesium di-n-propylate] lying between 1 % and 10 % (W/V), and up to concentrations of n-propanol less than 10 % (V/V).
• HFC preferably HFC 227
• the product of the invention contains between 3.8 and 4.5 % (W/V) of carbonated magnesium di-n-propylate, between 2 and 3 % (V/V) of n-propanol, the rest of the mixture consisting of the HFC diluent chosen from HFC 227 and HFC 134a, and the product of the invention of said formulation is especially suitable for use with spray systems.
• the product of the invention may contain an inert gas, for example, nitrogen, with a view to achieving additional pressure and propulsion.
• an inert gas for example, nitrogen
• the resulting diluted solutions of carbonated magnesium di-n-propylate may be applied by conventional methods, for example, by direct spray onto the cellulose-type material.
• This method of applying the de-acidification product does not require prior desiccation, under vacuum, of the cellulose-type material, as the distribution and impregnation attained using the spray is very uniform and does not lead to the accumulation of any type of deposit or residue on the cellulose-type material to be treated. In general, it is advisable to work in a fume cupboard and use means of personal protection to avoid inhaling the spray.
• the product of de-acidification product of the cellulose-type material can also be carried out by means of dissolving in HFC to a known concentration, for the bulk de-acidification of books and documents, using the equipment and method described in the Spanish patent application P9600016 filed by the same applicant.
• the apparatus described is formed of a treatment chamber, which serves for the drying stages under vacuum prior to impregnation and recovery of solvent by evaporation-condensation.
• the invention also provides a method for de-acidification of cellulose-type material, which comprises the application, of a quantity sufficient of the product of the invention for de-acidifying the cellulose-type material to be treated.
• the product of the invention may be applied to the cellulose-type material to be treated by means of a bulk de-acidification system or by spray.
• the product of the invention can be obtained through a procedure that comprises:
• the concentration of carbonated magnesium di-n-propylate in said alcoholic solution lies between 30% and 70% (W/V).
• the product of the invention may contain an inert gas, for example, nitrogen.
• N-propanol (Panreac quality PS) is used with a water content of less than 0.1%. The residual water is almost completely eliminated following the procedure now described.
• magnesium strip are treated with 0.5 1 of dilute hydrochloric acid (approximately 5 % concentration) for a short time, normally 5 minutes, shaking in an open Erlenmeyer flask so that the hydrogen is eliminated. Then it is quickly washed with distilled water several times until the acid is completely eliminated. This elimination can be verified by means of conventional methods for quantifying the presence of chloride ions.
• the next step is to eliminate the water with successive washes, usually 2 or 3 washes, with absolute ethanol, before drying between filter papers and storing in a topaz flask under a nitrogen atmosphere.
• the strip is then dried in an oven at 100° C for 15 minutes, allowed to cool, always under dry nitrogen atmosphere, and the container hermetically sealed.
• the composition of the azeotrope is 48 % propanol and 52 % toluene and the boiling point (b.p.) of the azeotrope is 92° C [b.p. of propanol: 97.2° C, and b.p. of toluene: 110.6° C].
• said suspension of magnesium di-n-propylate in n-propanol has been cooled as the reaction with carbon dioxide is exothermic and goes more slowly and with slight decomposition of the products if carried out at temperatures greater than 50° C.
• the solid starting product [magnesium di-n-propylate] is transformed into a soluble form consisting of carbonated magnesium di-n-propylate, by raising the temperature to 45-50° C.
• reaction is over after 5-6 hours, and this is manifest by a drop in the temperature of the reaction mixture to room temperature.
• the dark insoluble solid particles are allowed to sediment out until they deposit on the bottom of the flask leaving a clear and transparent solution, over a time period of 48.72 hours and the solution of carbonated magnesium di-n-propylate is collected and transferred by suction under vacuum to the recipient for loading and dosing.
• the amount of carbonated magnesium di-n-propylate obtained from 6 mols of magnesium is 912 g in approximately 1,700 g of n-propanol, giving rise to a concentration in the carbonated product of the order of 54 % by weight.
• the carbonated magnesium di-n-propylate is purified by total evaporation of n-propanol under vacuum, and; (i) its magnesium content is analysed by complexometric titration, and (ii) its bound carbon dioxide content analysed through decomposition of a sample with concentrated phosphoric acid, and collection of CO 2 in a series of towers containing a known excess of barium hydroxide.
• the solubility of carbonated magnesium di-n-propylate in HFC 227 reaches values lying between 1 g% up to 200 g%. Thus it can be affirmed that the product is soluble at any proportion.
• the carbonated magnesium di-n-propylate is soluble in HFC 134a in analogue proportions.
• a suspension of magnesium di-n-propylate, a light grey-coloured solid, is obtained in n-propanol.
• the mixture is allowed to cool before proceeding to the next step in the reaction.
• 770-800 g of product are obtained, with yields between 90-92%.
• the reaction is exorthermic, reaching temperatures of 45° C.
• the solid starting product [magnesium di-n-propylate] is transformed into a soluble form consisting of carbonated magnesium di-n-propylate.
• the reaction is over after 4-6 hours.
• the temperature drops to room temperature the product is allowed to sediment out for 24-48 hours until the solid dark insoluble particles are lying at the bottom of the flask, and the solution appears clear and transparent.
• This solution may be collected by decantation or even better transferred by suction under vacuum, to recipients appropriate for loading, dilution or dosing.
• the magnesium content in this solution measured by complexometric titration, is greater than 5 %, which represents 40 % as carbonated magnesium di-n-propylate.
• the product is purified by total evaporation of n-propanol under vacuum, and the Mg content analysed by complexometric titration, and the CO 2 content is determined by decomposition of a sample with concentrated phosphoric acid and collection of CO 2 in a series of towers containing a known excess of barium hydroxide. The results obtained coincide with these mentioned in Example 1.5.
• the absorption of the product for de-acidification constitutes an indication of the alkaline reserve created in the cellulose-type material.
• This reservoir may play an important role in combating the degradation of cellulose by acid hydrolysis and, therefore, is going to contribute to the better preservation of the cellulose material.
• the cellulose-type material used was paper in different stages of ageing (without ageing and submitted to accelerated ageing).
• the assay carried out consisted of applying the product for de-acidifying the paper to the sheets of paper, either to one side or to both sides, and then determining the alkaline reserve created in the paper. Assays have been affected in different conditions of ageing of the paper. The results obtained are shown in Tables 1-3.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HCl No. of HCl equivalents.
• NaOH No. of NaOH equivalents.
• the alkaline reserve created by the product of the invention is very much better (a little greater than three times better) than that created using Bookkeeper.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HCl No. of HCl equivalents.
• NaOH No. of NaOH equivalents.
• the alkaline reserve created by the product of the invention is very much better (between 2.5 and 3.5 times better) than that created using Bookkeeper.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HFC diluent selected from HFC 134a and HFC 227, at 4 %.
• HCl No. of HCl equivalents.
• NaOH No. of NaOH equivalents.
• the alkaline reserve created by the. product of the invention is very much better (between 3.7 and 4.2 times approximately) than that created using Bookkeeper.

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• 1999
  • 1999-07-29 DE DE69908955T patent/DE69908955T2/de not_active Expired - Lifetime
  • 1999-07-29 MX MXPA01001211A patent/MXPA01001211A/es not_active IP Right Cessation
  • 1999-07-29 AU AU52906/99A patent/AU5290699A/en not_active Abandoned
  • 1999-07-29 PT PT99938395T patent/PT1111128E/pt unknown
  • 1999-07-29 WO PCT/ES1999/000242 patent/WO2000008250A2/es active IP Right Grant
  • 1999-07-29 BR BRPI9912591-9A patent/BR9912591B1/pt not_active IP Right Cessation
  • 1999-07-29 CA CA002339021A patent/CA2339021C/en not_active Expired - Fee Related
  • 1999-07-29 AT AT99938395T patent/ATE243283T1/de not_active IP Right Cessation
  • 1999-07-29 DK DK99938395T patent/DK1111128T3/da active
  • 1999-07-29 ES ES99938395T patent/ES2201754T3/es not_active Expired - Lifetime
  • 1999-07-29 EP EP99938395A patent/EP1111128B1/en not_active Expired - Lifetime

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