RU2109769C1 - Method of pore forming of required parameters in chemically stable polymeric material - Google Patents

Abstract

FIELD: polymers. SUBSTANCE: invention relates to preparing highly thermostable polymeric material of required structure and complex properties which can be used for separation of technological liquid components in food industry. Method involves addition of finely dispersed ferromagnetic vehicle to solution or melt of polymer and composition applying on forming surface followed by effect of magnetic field on composition and hardening for structure fixing. Then composition is subjected for acid effect up to pores formation from dissolved vehicle particles. EFFECT: improved method of forming, enhanced effectiveness of composition. 1 tbl

Description

 The invention relates to the production of a highly heat-resistant polymer material with a given structure and a set of properties, capable of effectively separating the components of process liquids and food production products.

 Known methods for producing porous materials are based on the formation of the structure of a high molecular weight substance corresponding to a given permeability with respect to shared components.

 The separation efficiency of the components is determined by the chemical structure of the high molecular weight compound, which ensures the formation of micropores of a given size and specific intermolecular interaction of the membrane material with the components of the mixture being separated. The regeneration of the initial properties of porous materials after their depreciation in most cases is a complex and lengthy process, sometimes requiring the use of scarce solvents. The acute thermal effect during membrane cleaning, as a rule, leads to degradation of the porous structure.

 Known methods for producing polymeric finely porous materials by adding to solutions or melts of resin, insoluble and resistant to solvent, a separable system, but dissolving in another solvent when cleaning a porous material. The product is molded from the resulting mixture, and then the formed product is contacted with a filling solvent, and as a result, pores are formed in the formed product [1].

 One of the methods for creating a porous structure is a method for producing membranes by pouring a solution of ethyl cellulose on a forming surface with subsequent coagulation [2]. However, the obtained porous materials have low chemical and thermal resistance, which impedes the widespread use of materials and their cleaning by high temperature exposure.

 There are methods for producing polymeric porous materials with sufficiently high operational characteristics and resistance to aggressive media, which is achieved both by using a heat-resistant polymer as the basis, for example [3], and by additional processing of the porous material [4].

However, for all these methods, porous materials with difficult to control shape, pore size, and fluid transmission ability are obtained, which affects the efficiency of particle retention during separation of the components of liquid media. Despite the high performance of existing porous materials, the processes of separation of the media are associated with a number of problems, for example, such as:
a) difficulty in choosing operating conditions (narrow ranges of filtered media and operating temperatures),
b) prediction of the properties of porous materials, the formation of materials with a given set of properties that meet the requirements of operating conditions.

 The closest in technical essence to the proposed method for the formation of pores in a polymer material with specified parameters is a method of obtaining material by applying to a forming surface, followed by coagulation of a composition based on a polymer solution containing functional groups in the precipitator [5].

 However, highly heat-resistant polymeric materials suitable for the production of membranes that do not change their properties during thermal cleaning, unfortunately, are not always suitable for the formation of macropores of a given size, shape and orientation.

 The objective of the invention is to obtain, on the basis of high-temperature-resistant high-molecular weight compounds of a new generation of porous materials with specified parameters of the porous structure and a set of properties that allow the regeneration of membranes by raising the temperature to the necessary (for the decomposition of substances clogged pores) values and the possibility of using cheap and non-deficient solvents, the action which is not susceptible to the base polymer of the porous material.

 This is achieved by the fact that a finely dispersed ferromagnetic filler is introduced into the solution or melt of the chemically resistant polymer, the resulting composition is applied to the forming surface, the magnetic composition is applied to the resulting composition, curing is carried out to fix the structure, the composition is exposed to acid until pores are formed from the dissolved particles of the filler, followed by washing and drying.

In connection with the use of reagents that dissolve the metal filler, it is necessary that this solvent meets the following requirements:
a) the solvent should not degrade the polymer base of the membranes;
b) must dissolve the metal filler.

 Thus, the polymer used must be chemically resistant to a reagent dissolving the ferromagnetic filler.

 The chain structures of the dispersed filler, the transverse dimensions of which are determined by the particle size of the dispersed ferromagnetic filler, and the length and direction are determined by the orientation of the magnetic field [6] with respect to the surface of the molded porous material, are then etched with acid (the chemical nature of which is selected in accordance with the chemical nature of the dispersed filler) .

 The invention is carried out as follows.

). Полученную композицию (в случае раствора) наносят на подложку - стекло, либо, если это расплав, пропускают через плоскощелевую головку, затем неотвержденную еще пленку подвергают воздействию магнитного поля напряженностью 600-900 Э, где в процессе отверждения (пленкообразования) происходит ориентация частиц ферромагнитного наполнителя в цепочечные структуры, что обеспечивает формирование заданной структуры и свойств полимерного материала. Далее изделие отверждают. Полученное изделие - пленку обрабатывают кислотой, удаляющей ферромагнитный наполнитель, в результате чего образуются поры заданного диаметра, геометрии и направленности.Example. A 5% colloidal dispersed powdered ferromagnetic filler (with a particle size of 600-700 is introduced into the solution (or melt) of the highly heat-resistant and chemically resistant polymer

) The resulting composition (in the case of a solution) is applied to a substrate - glass, or, if it is a melt, passed through a flat slot head, then the uncured film is still exposed to a magnetic field of 600-900 Oe, where the particles of the ferromagnetic filler are oriented during curing (film formation) into chain structures, which ensures the formation of a given structure and properties of the polymer material. Further, the product is cured. The resulting product - the film is treated with acid that removes the ferromagnetic filler, resulting in the formation of pores of a given diameter, geometry and direction.

. Полученную композицию наносят на подложку - стекло и выдерживают при температуре 50^oC в течение 10 мин, затем образец подвергают воздействию магнитного поля напряженностью 600-900 Э, где в процессе пленкообразования происходит ориентация частиц ферромагнитного наполнителя -Ni в цепочечные структуры. Магнитное поле формируется таким образом, чтобы направление и форма силовых линий соответствовали направлению формируемых пор. Далее образец погружают в осадительную ванну с водой, температура которой 10-20^oC, и выдерживают 40 мин. В процессе коагуляции (мокрого формирования) происходит вытеснение органического растворителя водой. Затем пленку досушивают при комнатной температуре. Полученную пленку обрабатывают кислотой, например соляной (10%-ной концентрации), в результате чего образуются поры заданных характеристик.Example 1. In a 10% solution of a highly heat-resistant and chemically resistant polymer of 1,3,4-polyoxadiazole in N-methylpyrrolidone, 5% colloidal dispersed powdered carbonyl nickel with a particle size of 600-700 is introduced

. The resulting composition is applied to a glass substrate and kept at a temperature of 50 ^o C for 10 minutes, then the sample is exposed to a magnetic field of 600-900 Oe, where the particles of the ferromagnetic filler -Ni are oriented into chain structures during film formation. A magnetic field is formed in such a way that the direction and shape of the lines of force correspond to the direction of the formed pores. Next, the sample is immersed in a precipitation bath with water, the temperature of which is 10-20 ^o C, and incubated for 40 minutes In the process of coagulation (wet formation), the organic solvent is displaced by water. Then the film is dried at room temperature. The resulting film is treated with an acid, for example, hydrochloric (10% concentration), resulting in the formation of pores of specified characteristics.

The permeability of the porous material in distilled water 170 l / m • h (20 ^o C, 0.1 MPa).

Examples 2 and 3. Get analogously to example 1 when changing the aging time of the sample at a temperature of 50 ^o C.

 Examples 4-6. Get analogously to example 1, changing the duration of aging of the samples in a precipitation bath. Varying the modes of obtaining samples and their properties are given in the table.

 Example 7. Carried out as in example 1, as a filler using colloidal dispersed powdered iron.

 The properties of the porous material are given in the table.

 Example 8. Obtained analogously to example 7. The resulting film is treated with hydrochloric acid of 30% concentration, resulting in the formation of pores of desired characteristics.

Example 9. A 5% colloidal dispersed powdered ferromagnetic filler (with a particle size of 600-700 ^o A) is introduced into the polymer melt (polypropylene). The mixture is homogenized in an extruder at a melt temperature at the outlet of the extruder head of 180 ^o C. The resulting rod is cooled, cut into granules, from which a film is formed on the extruder with a slit head. The temperature in the extruder zones: 1 zone -155 ^o C, 2 zone 180 ^o C, 3 zone 210 ^o C. The properties of the porous material are given in the table.

 Example 10. According to example 9, injected 5% of a colloidal dispersed ferromagnetic filler with a particle size of 1.5 μm (technological conditions according to example 1).

 Example 11. According to example 9. The resulting film is treated with 15% hydrochloric acid, resulting in the formation of pores of desired characteristics.

 As can be seen from the data presented (see table), the introduction of a dispersed ferromagnetic filler into the polymer matrix, forming chain structures of a given type and direction under the influence of a magnetic field, allows the formation of porous structures characterized by high performance characteristics (porosity, selectivity).

 A distinctive feature of the proposed method is that varying the shape and size of the particles of the ferromagnetic filler makes it possible to directionally form membranes with predetermined parameters of the porous structure and, accordingly, a set of properties in comparison with the known methods.

The proposed method provides several advantages, allows you to:
- create membranes with a given pore size and shape,
- to form porous structures with the necessary orientation, distribution, number of pores,
- to predict the properties of membranes,
- the use of high temperature resistant polymers as the basis allows the purification of spent membranes by decomposition of substances that contaminate the membrane due to their thermo-oxidative degradation.

Claims (1)

 A method of forming pores with predetermined parameters in a chemical-resistant polymer material, characterized in that a finely dispersed ferromagnetic filler is introduced into the solution or melt of the chemical-resistant polymer, the resulting composition is applied to the forming surface, a magnetic field is applied to the resulting composition, curing is carried out to fix the structure, and the composition is exposed to acid until the formation of pores from the dissolved particles of the filler, followed by washing and drying.

Images