SE181468C1 - - Google Patents

Description

Inventors: J A Orsino, D F Herman and J J Brancato Priority as of February 11, 1958 (USA) The present invention relates to a moldable material, consisting of a cellulosic material having an outer layer of a polymer, and a process for producing the same.

Many methods have been proposed for the chemical treatment of cellulosic materials to alter their properties in various ways, e.g. The present invention relates in particular to a new and improved process for modifying the cellulosic materials so as to produce a new cellulose-carbonate composition which is made from nathrea ares for the purpose of modifying the grip of their flame-retardant fabrics, for providing water-repellent properties, etc. hydrophobic. Articles made from a soft composition are water repellent or water resistant depending on the degree of modification and the physical structure of the article.

The usual procedure for making cellulosic materials water-repellent has hitherto been to impregnate them with various substances, selected with regard to the use of the finished product. One type of + antigen used impregnating agent is paraffin wax or similar materials, which provide a usable degree of water repellent properties of paper and which to some extent are also useful for making spoken and similar 'water resistant'. Such materials suffer from the disadvantage that they have a tendency to fall off in flakes when the material is bent repeatedly, the water-repellent property being increased along the bend. They also do not require chemical washing or such higher temperatures, which usually occur during ironing and in contact with hot water shoes, e.g. at paper bakeries for coffee.

Another group of impregnating agents, which are commonly used, as the inadequacy of wax impregnating agents makes them inadvertent, or the synthetic resins. The treatment with this type of material is generally carried out by dipping the material to be treated in a solution of a suitable synthetic resin in a solvent or by spraying such a solution on the material either during the final manufacturing step or thereafter. Among the synthetic resins used in processes of this type, mention may be made of urea formaldehyde resin, vinyl plastic, cellulose derivatives and the like. Methods based on impregnation with such synthetic resins as these eliminate to some extent some of the disadvantages of wax impregnation. On the other hand, they suffer from certain other disadvantages, in particular the fact that the synthetic resins must be applied in the form of a solution and that the deposition of the synthetic resin on the fiber makes it difficult to evaporate the solvent, which is an expensive and even dangerous process. In order for the process to be economically feasible, it is also necessary to collect and recycle the preferred solvent, which entails further expensive and cumbersome steps in the process.

The synthetic resin impregnated products Wilma also have a lot to wish for, although they eliminate some of the illegality of wax impregnated materials. They are much more resistant to the effects of moderate heating, but like the wax-impregnated materials become enlarged at higher temperatures. The impregnation is also still removable with ordinary solvents for chemical washing, although less fast than the wax impregnation.

The present moldable materials can be characterized (Wray, that the individual cellulose fibers are completely or partially coated with polyethylene, polypropylene, polybutadiene or polyisoprene. The cellulosic material is present in the lamplia in the form of particles, fibers or threads.

The process according to the invention is characterized in that a cellulosic material is reacted with a titanium or zirconium compound and an organometallic alkylating or arylating agent, after which the cellulosic material thus treated is in contact with ethylene, propylene, butadiene or isoprene for a sufficiently long time. time for the formation of a polymer on the cellulosic material. The titanium or zirconium compound is suitably composed of a tetrachloride or an ester. As the organometallic alkylating agent, a Grignard reagent or an aluminum alkyl can be used.

The present moldable cellulosic materials have improved water repellent properties and are resistant to normal chemical wash solvents.

Cellulosic materials useful in the invention include fabrics, e.g. of cotton, flax, regenerated cellulose, such as viscose silk, copper silk and acetate silk, in addition to natural fibers, such as hemp, wood and wood products, building boards, paper, tramjiil, sawdust and the like. In addition, substituted cellulosic materials can be used, such as cellulose acetate, ethylcellulose, cellulose nitrate, etc.

The novel compositions prepared according to the present process are cellulosic materials which are modified in that they contain, in intimate connection, particles of carbonate polymers. The indicated compound is not such a simple mechanical mixture which can be obtained by mechanical mixing of cellulosic material with the polymer. Rather, it is marked by the presence of polymer beads or buttons, distributed on the surface of the cellulosic fibers. These polymer particles, which may be completely separated or to some extent fused together, adhere to the surface of the cellulosic fibers as if they are held by chemical bonds or correspondingly strong bonding forces. The most active regions in the cellulose molecule are the hydroxyl groups and it is believed that at least initially the reactions which ultimately lead to the formation of polymer beads take place at the hydroxyl groups of the cellulose. According to the present process, the cellulose is treated either before the polymerization step or simultaneously with a titanium or zirconium compound. It is believed that the metal atom (titanium or zirconium) replaces the hydrogen atom in a hydroxyl group in the cellulose, leading to a modified cellulose structure having catalytically active regions in which the hydroxyl groups have reacted in this way.

The polymerization then takes place at the catalytically active areas along the cellulose chain, so that the polymer produced is intimately flattened in the cellulose. Before the polymerization is complete, the catalyst is cooled in the usual way, e.g. by adding alcohol to the system with subsequent washing with additional alcohol or the like to remove catalyst residues. This process can lead to the cleavage of the bond between the cellulose molecule and the catalytically active group, so that it does not restore direct direct covalent chemical bonding between the cellulose and the polyolefinic part of the composition. Nevertheless, the polyolefin remains unextractable with common solvents, indicating that the composition is not a simple mixture of cellulose and polyolefin. This behavior seems to show that the cellulose and the polyethylene molecules are so intertwined that they behave as if they were chemically bound, although in reality this may not be the case.

The exact scheme of the reactions which take place and the exact structure of the modified cellulosic material prepared according to the present process have not yet been determined, and the above description of the structure of the composition is therefore not to be construed as limiting the invention, but merely as an experiment. to ash it. In this way, however, the observed facts are explained, that when one. olefinically unsaturated hydrocarbon monomer is polymerized in the presence of a cellulosic fiber treated with titanium or zirconium compound or together with a cellulosic fiber under conditions which promote simultaneous treatment with a titanium or zirconium compound thereof, the obtained fiber being bonded along its entire length to particles of the polymer, which behaves as if it were chemically bound to the cellulosic fiber. Nar daremot en. hydrocarbon monomer is polymerized in the presence of unmodified cellulose or under conditions which do not promote the treatment with titanium or zirconium compound of the cellulose hydroxyl groups, the product is a simple mixture of cellulose and polymer particles.

Numerous methods are obvious from the treatment with the titanium or zirconium compound of cellulose during simultaneous or subsequent polymerization of an above-mentioned olefinically unsaturated hydrocarbon monomer in the presence of the cellulose. However, one of the most suitable methods is to treat the cellulose with titanium or zirconium compound by edge, e.g. by treating it with titanium or zirconium tetrachloride or with a suitable ester, such as tetrabutyl titanate, tetrabutyl zirconate, etc., and by subsequently transferring the metal atom of the treated cellulose to a form containing a metal-carbon image flake. This can be done with the aid of known organometallic alkylating or arylating agents, such as grignard reagents or alkyl and aryl compounds of lithium, sodium, cadmium, zinc, aluminum, etc. When this transfer has taken place, the cellulose will contain catalytically active contra on the stalls in which introduced by the titanium or zirconium compound. - 181 968 —3 The reaction conditions are mild. Titanium or zirconium introduction can be carried out quickly at room temperature. Conditions, which are different from the polymerization, can vary widely, but in general it is convenient to carry out the polymerization at temperatures between about 20 and 80 ° C and at pressures from atmospheric pressure up to about 7 kp / cm 2.

The polymerization takes place rapidly, and a reaction time of 2-12 hours is generally sufficient to give a significant deposition of polymer on the cellulose surface. Shorter or longer contact times can be used depending on the desired degree of modification.

The process of the invention is illustrated in the following examples.

Example 1. 24 g wad of mechanical pulp was dispersed in the dry state in 1400 ml of toluene. The air in the vessel was displaced with nitrogen and 0.0316 moles of TiCl 4 was added to the dispersion. The mixture reacted for 0.5 hours at room temperature to produce titanium inf 5-ring in the cellulose, after which 0.075 mol of methylmagnesium bromide was added. The temperature was raised and maintained at 50-60 ° C, while a stream of ethylene gas was passed through the mixture. The color changed from orange Over markt grOn to almost black. The ethylene gas flow was continued for 6 hours, until the rate of absorption became negligible. The amount of ethylene absorbed was approximately equal to the amount of cellulose wadding in the reaction vessel.

The solution was cooled and spatulated by adding an equal volume of methanol, after which the cooled solution was filtered and washed with additional methanol. After drying, the filter cake consisted of a powdered cellulose-polyethylene composition containing about 50% polyethylene.

A photomicrograph of the composition produced shows a fibrous network of cellulosic fibers having an average diameter of about 20-30 .mu.m and more flakes "of polyethylene, which presently present as a sticky coating on the surface of the cellulosic fibers, while no open the areas between the cellulose fibers.

The product was used to make accumulator separators by transferring it to sheet form in a paper machine and then pressing it lightly together in a heated mold. The separator was porous and slightly permeable to water and to dilute sulfuric acid, but it was very resistant to acid. The finished separator. spoke Over 2 hours immersion in conc. sulfuric acid (spec. weight 1.84) at room temperature without visible charring.

Example 2. 40 g of cellulose wadding was dispersed in 1400 ml of toluene. The air in the vessel was displaced with nitrogen and 0.0158 moles of titanium tetrachloride was added. After 0.5 hours standing for titanium to be introduced into the cellulose, 0.0474 moles of triobutylaluminum was added. The temperature was then raised and kept at 50-60 ° C, while ethylene gas was passed through the mixture until the absorption of gas became insignificant. The mixture was then cooled and diluted with methanol, filtered, washed and dried as described in Example 1. The product obtained in good yield was a cellulose-polyethylene composition containing about 35% polyethylene. On microscopic examination, the product showed the typical appearance of compositions prepared according to the present process, i.e. it consisted of long cellulose fibers and on ordinary fibers there were beads or buttons of polymerized carbonate, fixed at different points along the length of the fibers. An electron microscope photograph showed, in addition to the larger beads visible in the microscope for ordinary light, a large number of small beads, some of which were fused together into a coherent layer on the surface of each fiber. Fa, if even flake polymer particle was present in the space between the cellulose fibers at the examination in light microscope and in electron microscope.

Example 3. 24 g of cellulose acetate were suspended in 11400 ml of toluene in a closed vessel, and the air was purged with nitrogen gas, after which 0.023 mol of titanium tetrachloride was added. The mixture was allowed to stand for 0.5 hours to allow the introduction of titanium, after which 0.055 mol of methylmagnesium bromide was added. The temperature was raised to 50 DEG C. (300 DEG C. and kept at this range while ethylene gas was started in the solution until no more was absorbed. The mixture was cooled and diluted with methanol, as in the previous example, washed and dried.

The product contained 20% polyethylene and was not wetted by water and was very resistant to cone infestation. sulfuric acid. Untreated cellulose acetate, on the other hand, is slightly moistened by the water and dissolved in conc. sulfuric acid.

Example 4. The procedure of Example 1 was repeated with the change that 0.0316 moles of tetrabutyl zirconate was used in place of the titanium tetrachloride. The product was a cellulose polyethylene composition very similar to that prepared according to Example 1.

Example 5. The procedure of Example 2 was repeated with the change that propylene gas was used instead of ethylene gas. The product was a cellulosic polypropylene composition containing non-extractable polypropylene.

Example 6. The procedure of Example 1 was repeated with the change that a light cell was used instead of mechanical pulp. lulosagarn (cotton yarn). The treated yarn was woven into fabric, the appearance and grip of the vans resembled untreated cotton fabric, but it was very water-repellent and acid-resistant and suitable for rain protection, protective laboratory clothes and the like.

Example 7. 25 g of maid, purified sulphite paper pulp was dispersed in 450 ml of benzene under dry conditions. The air in the container was replaced with nitrogen gas and 0.0054 moles of titanium tetrachloride in 50 ml of dry benzene was added to the dispersion. The mixture was allowed to react for 0.5 hours at room temperature to effect a titanation of the cellulose, after which 0.0054 moles of triethylaluminum in heptane and then 50 g of isoprene were added. The polymerization began spontaneously, as evidenced by the fact that the temperature rose from 26 ° C to 37 ° C over the course of 0.5 hours. When the temperature reached a temperature of 36 ° C over a further 40 minutes, the mixture was gently warmed to 74 ° C over 1.5 hours and kept at this temperature for one hour.

The catalyst was stopped or cleaved by the addition of 25 ml of methanol. The solid was recovered by centrifugation, washing, twice with benzene, filtration and drying. The solid, after drying, was a powdered cellulose-polyisoprene composition containing about 13% by weight of polyisoprene.

Compositions prepared according to the present process are useful for many purposes due to their chemical and physical properties. They are hydrophobic, organophilic cellulosic materials and can be processed into various shaped, pressed and cast foresums, containers, tea fibers, protective coatings and the like, in particular where resistance to water wetting, resistance to dissolution in organic solvents and resistance to concentrated mineral acids are desirable. They can be used for such different objects as lead-acid battery separators, accumulator fillers, filter media, containers for hot and cold drinks, water-repellent protective fabric, beachwear, etc.

Claims (5)

Patent claim: A mouldable material, consisting of an cellulose material having an outer layer of a polymer, characterized in that the individual cellulose fibers are coated or partially coated with polyethylene, polypropylene, polybutadiene or polyisoprene. Material according to claim 1, characterized in that the cellulosic material is in the form of particles, fibers or threads. 3. A process for the preparation of a material according to any one of claims 1 and 2, characterized in that a cellulosic material is reacted with a titanium or zirconium compound and organometallic alkylating or arylating agent, after which the cellulosic material treated on such salt is kept in contact with ethylene , propylene, butadiene or isoprene for a sufficiently long time to form a polymer on the cellulosic material. 4. A process according to claim 3, characterized in that the titanium or zirconium compound consists of a tetrachloride or an ester. 5. A process according to claim 4, characterized in that the organometallic alkylating agent is prepared from a grignard reagent or a. aluminum alkyl. Request publications: Patents for France 1,140,362, 1,155,945; Great Britain 664 795. Stockholm 1962. Kungl. Boktr. P. A. Norstedt 8c Saner. 621089