EP4196441A2 - Procédé de modification du minéral halloysite et halloysite modifié par le biais du procédé de modification - Google Patents

Procédé de modification du minéral halloysite et halloysite modifié par le biais du procédé de modification

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Publication number
EP4196441A2
EP4196441A2 EP21856360.9A EP21856360A EP4196441A2 EP 4196441 A2 EP4196441 A2 EP 4196441A2 EP 21856360 A EP21856360 A EP 21856360A EP 4196441 A2 EP4196441 A2 EP 4196441A2
Authority
EP
European Patent Office
Prior art keywords
halloysite
production method
modified
modified halloysite
silane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21856360.9A
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German (de)
English (en)
Inventor
Tugba UCAR DEMIR
Adnan ALTAS
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Esan Eczacibasi Endustriyel Hammaddeler Sanayi Ve Ticaret AS
Original Assignee
Esan Eczacibasi Endustriyel Hammaddeler Sanayi Ve Ticaret AS
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Publication date
Application filed by Esan Eczacibasi Endustriyel Hammaddeler Sanayi Ve Ticaret AS filed Critical Esan Eczacibasi Endustriyel Hammaddeler Sanayi Ve Ticaret AS
Publication of EP4196441A2 publication Critical patent/EP4196441A2/fr
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/20—Silicates
    • C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
    • C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
    • C01B33/40—Clays

Definitions

  • the invention relates to a modified halloysite modified and provided with functional properties without damaging the nanotube contents and a modification method for obtaining said modified halloysite.
  • Halloysite is a mineral belonging to the kaolin group and exists in the form of nanotube during its formation in the nature.
  • this mineral having a stratified structure as in the minerals of the clay group, the layers, unlike those of the other minerals, bend into a nanotube form due to their surface loads and stabilities.
  • not every halloysite in the nature has the same shape; they have different properties because of their impurity contents, the presence of the wall rocks, the form of the developed tubes and the water content of the tubes.
  • halloysite has usage in the porcelain industry.
  • impurities it contains and its surface properties it may not be used in the other fields, especially in the polymer structures, in the paint structures and as a catalyst where its nanotube contents could provide contribution.
  • the additives conferring said properties are added directly to the textile product, paint and polymer formulations or a surface coating process is performed for these applications. Conferring said properties in such practices may generally be achieved by way of application of the additives/agents in liquid state on the surface. However, it is not possible to achieve controlled release and the effect of the agents used in liquid state is observed to decrease over time in such practices. Accordingly, the unavailability of materials, which are capable of performing controlled release and thus enabling a prolonged effect to be achieved, as well as the necessity to make it possible for these materials to be fed in powder form in cases where it is not preferred or possible to perform the same in liquid state represent a drawback encountered in the state of the art.
  • the modified halloysites having functionalized mineral surfaces are obtained by way of purifying halloysite, which has a nanotube content in its naturally obtained state but is unable to be used in any field other than ceramics, and doping, after the purification, the agents specified for the use of halloysite in different applications, such as polymer, paint and coating, in the nanotubes by preserving the tubular structure, and the method for obtaining said modified halloysites is described.
  • An object of the invention is to obtain a halloysite the impurities in the structure of which are removed without damaging the nanotubular structure.
  • Another object of the invention is to obtain a functional halloysite, which is modified via surface, via interlayer space or via tube interior.
  • Another object of the invention is to obtain a halloysite, the UV barrier, impact resistance, thermal properties, strength and/or antimicrobial properties of which are improved as a result of modification.
  • Figure 4 XRD pattern of halloysite, which has been ground in the mill, expanded in water and sieved and subjected to centrifugation
  • Figure 7 SEM image of halloysite after the clay expansion in the mill and the sieving
  • Figure 8 SEM image of halloysite after the purification by centrifugation
  • Figure 9 A graph comparing the starting halloysite with halloysite treated with the acid at 40°C while the pH is 1,5
  • Figure 10 A graph comparing the dry/wet grinding with the starting halloysite while the pH is 1,5 (room temperature - purified halloysite/quaternary ammonium salt: 1/0,3)
  • Figure 11 A graph comparing the dry/wet grinding with the starting halloysite while the pH is 1,5 (room temperature - purified halloysite/quaternary ammonium salt: 1/0,5)
  • Figure 12 A display showing the variation in the interlayer space values with increasing quantity of quaternary ammonium salt
  • Figure 13 A graph comparing the interlayer space values according to different pH and temperature values
  • Figure 14 A comparison graph for the pH values at room temperature
  • Figure 15 SEM image of halloysite after acid activation
  • Figure 16 A representation of XRD patterns after the modification with vinyl benzylaminoethylaminopropyltrimethoxy silane (Silane A)
  • Figure 17 A representation of XRD patterns after the modification with n-octyltrimethoxy silane (Silane B)
  • Figure 18 A representation of XRD patterns after the alcohol addition and modification with vinyl benzylaminoethylaminopropyltrimethoxy silane (Silane A)
  • Figure 19 A representation of XRD patterns after the alcohol addition and modification with n-octyltrimethoxy silane (Silane B)
  • Figure 20 A representation of XRD patterns after the sulfuric acid addition and modification with vinyl benzylaminoethylaminopropyltrimethoxy silane (Silane A)
  • Figure 21 A representation of XRD patterns after the sulfuric acid addition and modification with n-octyltrimethoxy silane (Silane B)
  • Figure 22 A representation of XRD patterns after the acetic acid addition and modification with vinyl benzylaminoethylaminopropyltrimethoxy silane (Silane A)
  • Figure 23 A representation of XRD patterns after the acetic acid addition and modification with n-octyltrimethoxy silane (Silane B)
  • Figure 25 SEM image of the product with 1% silane content prepared with vinyl benzylaminoethylaminopropyltrimethoxy silane (Silane A) without using any dispersing medium
  • Figure 26 SEM image of the product with 1% silane content prepared with n- octyltrimethoxy silane (Silane B) without using any dispersing medium
  • Figure 31 Comparison of the trials performed with varying quantities of octadecane
  • Figure 32 Morphological images (TEM) after the addition of the agent PEG 600 at 1%
  • Figure 33 Morphological images (TEM) after the addition of the agent PEG 1000 at 1%
  • Figure 34 Morphological images (TEM) after the addition of the agent eicosane at 1%
  • Figure 35 Morphological images (SEM) after the addition of the agent octadecane at 1%
  • Figure 36 Morphological images (SEM) after the addition of the agent octadecane at 10%
  • Figure 37 Morphological images (TEM) after the addition of the agent octadecane at 1%
  • Figure 38 Morphological images (TEM) after the addition of the agent octadecane at 10%
  • Table 19 Effect of the quantity of octadecane on the surface area and filtration time
  • Table 20 Comparison of the diameter and length values following the modification with the addition of the thermal agent at 1%, based on TEM results
  • the invention relates to a modified halloysite modified and provided with functional properties without damaging the nanotube contents and a modification method for obtaining said modified halloysite.
  • the invention relates to a modified halloysite, which is purified and rendered open to surface binding and provided with functional properties by way of being modified with different agents in such a way that the nanotube content of the same is preserved and the physical and morphological structure of the same is not damaged, and to a method for the production of said halloysite.
  • the properties of the halloysite mineral were determined following the purification of the same via different methods and whether the tubular structure was deteriorated was examined, and the functional halloysites were obtained by conducting modification studies with agents chosen for different purposes.
  • the identification of the reserve characteristics and of the purification techniques for obtaining the halloysite mineral was carried out.
  • Obtaining the functionalized mineral surfaces by way of purifying halloysite, which has a nanotube content in its naturally obtained state but is unable to be used in any field other than ceramics, and doping, after the purification, the agents specified for different purposes in the nanotubes by preserving the tubular structure and ensuring that the halloysite preserves its properties after the modification process are the main objects of the study.
  • the modified halloysite obtained within the scope of the invention is modified after the purification process.
  • the product obtained as a result of each modification performed for different purposes is a functionalized powder halloysite product. While the obtained product may be used in the textiles for the thermal camouflage application, it is also possible for the same to become a powder antimicrobial mineral by the use of an antimicrobial additive. With the method developed within the scope of the invention, it is aimed to enable the use of the mineral for controlled release or as a nanocontainer.
  • the method for the production of modified halloysites according to the invention basically comprises three steps. These steps are purification, modification, and drying and grinding. Purification
  • the primary goal of the purification process is to bring the mineral into a state that is open to surface binding. Avoiding damage to the physical and morphological structure of the mineral and preserving the nanotube content are among the critical features of the purification process.
  • the first step of the purification process is the dispersion of the clay in a mill.
  • halloysite is enabled to disperse in water and the obtained sludge is sieved to remove the coarse-grained and/or hard minerals and the foreign matter like sand and quartz possible to be present within the mineral.
  • Said sieves may be preferred to have a size of 63 microns and/or 125 microns.
  • the purification is accomplished by means of a hydrocyclone. It is desired that the nanotube structures have not been damaged and the coarse-grained and hard minerals have been removed from the material after the purification.
  • the impurity value of the product after the purification process is determined by the properties of the starting material as well as the qualities and settings of the equipment used.
  • the cyclone diameter, the cyclone top outlet (vertex) and the cyclone bottom outlet opening (apex) of the cyclone used in the process of purification with hydrocyclone affect the grain size distribution of the product to be obtained. It is necessary to determine the parameters appropriate for obtaining a product of desired quality.
  • the cyclone diameter, the cyclone top outlet (vertex) and the cyclone bottom outlet opening (apex) are selected as 0,5"-l,5"; 5-7,5 cm and 1,5-4 cm, respectively.
  • the input halloysite values are 1055 g/L, dlO: 0,297, d50: 8,361 and d90: 42,606, and 100% of the material is below 75 microns.
  • Said study is conducted under a pressure of 1,5-2, 5 bars, preferably 2 bars. The values for the respective study are shown below.
  • the purification was performed in 2 stages.
  • the first stage weight per liter was determined as 1060 g/L
  • the cyclone top outlet (vertex) was set to 7,0 cm
  • the cyclone bottom outlet opening (apex) was set to 3,2 cm.
  • the under cyclone weight per liter was found as 1160 g/L
  • the above cyclone weight per liter was found as 1060 g/L. This shows that denser material passed to the bottom of the cyclone.
  • the same sample was passed through the system one more time under the same conditions and finer material was enabled to be obtained.
  • the under cyclone weight per liter was found as 1154 g/L, while the above cyclone weight per liter was found as 1044 g/L.
  • the average grain size of the sample at the top of the cyclone was found as 6 microns at the end of the first stage.
  • this value dropped to 3,8 microns and 100% of the material was enabled to be under 40 microns.
  • the input halloysite values are 1055 g/L, dlO: 0,297, d50: 8,361 and d90: 42,606, and 100% of the material is below 75 microns.
  • Said studies are conducted under a pressure of 1,5-2, 5 bars, preferably 2 bars. The values for the respective study are provided below.
  • the analyses were performed by taking samples from each stage. According to the analysis results, it is considered that the coarse-grained quartz mineral was removed from the system after the sieving process. It can be seen in the results of XRF that the SiCh content increased in the sieve-top sample. It was determined as a result of the mineralogical analysis that the quartz quantity decreased when this process was followed by the hydrocyclone stage. Since the halloysite and metahalloysite phases were detected in the sample over 125 microns, the refeed was performed into the system to enable the expansion in water and the recovery of the sample. The sample separated as waste after the studies was also examined.
  • the surface areas of the specimens taken from these samples were also monitored. Since the surface area of the coarse-grained minerals will be small, it is considered that they will accordingly reduce the average surface area value. Therefore, the determination of surface area was performed before and after the purification to determine whether the surface area had a tendency to increase after purification, i.e. whether the fine material was obtained.
  • the waste and sieve-top samples gave similar surface area values. It is believed that the values higher as compared to the standard sample were obtained as there was still some amount of halloysite in these products. To the contrary, the surface area value increased in the purified sample. Accordingly, it could be seen that the samples with fine grains and wide surface area could be obtained in the purification process. The specific surface area was increased to above 100-135 m 2 /g after the purification.
  • the grinding process is performed in order to reduce the physical size of the product before and/or after the purification process.
  • Said grinding process may be wet or dry grinding.
  • the wet and dry grinding studies were conducted in a jet mill or a hammer mill or a vertical shaft grinder.
  • the water was used for the grinding performed in wet medium.
  • the purification is achieved by way of centrifugation. It is desired that the nanotube structures are not damaged and the coarsegrained and hard minerals are removed from the material after the purification.
  • halloysite expanded in water that is first passed through preferably 63 or 125-micron sieves is fed to the centrifugation unit and sized under the influence of the centrifugal force.
  • the drum speed is in the range of 2500-4500 rpm
  • the differential speed is in the range of 6-8 rpm
  • the plate size is in the range of 90-130 mm
  • the valve opening is in the range of 15-35%.
  • the minerals coarse relative to the starting material were observed to begin leaving the system.
  • the metahalloysite phase is present in the fine product, i.e. the purified product output from the centrifugation unit
  • the gibbsite, alunite and a greater proportion of quartz phase are present in the coarse part, i.e. the waste.
  • the surface area values rose from 79 to 82 m 2 /g upon the removal of the impurities, and the surface area values increased to the levels of 110-140 m 2 /g upon the increase of the fine- grained product content in the main structure after the purification and upon the nanotubes becoming predominant.
  • the XRD pattern of halloysite ground in the mill, expanded in water, sieved and subjected to centrifugation is shown in Figure 4.
  • the purified product output from the centrifugation unit is coded as fine.
  • the SEM study was conducted with a view to make sure that the tube structures were not damaged in the purification by centrifugation.
  • the process performed subsequent to the purification is the process of modification of halloysite.
  • the halloysite mineral represents a stratified clay wound in the form of a spiral.
  • the groups Al + and OH- are present on the interior surface of halloysite and Si + ions are present on the exterior surface. Accordingly, it is possible to bind various chemical materials to the system via both surfaces.
  • the purified halloysite is referred to as clay in the following descriptions.
  • the halloysite mineral is modified with quaternary ammonium salts.
  • Said quaternary ammonium salt may be dimethyl dihydrogenated alkyl ammonium salt. Modification of halloysite with a quaternary ammonium salt may be used for the purposes of increasing the halloysite thermal resistance and flame retardation.
  • Raw halloysite which has a hydrophilic structure, is required to be brought into a form that is favored by the polymers, i.e. the organophilic form.
  • raw halloysite is brought into the organophilic form by way of an ion exchange reaction with the cationic surfactants containing the quaternary alkylammonium cations.
  • the ratio of purified halloysite (clay)/quaternary ammonium salt is in the range of 1 over 0,2-0, 6 by weight, i.e. in the range of 1/(0, 2 to 0,6) by weight.
  • 0,2-0, 6 unit of quaternary ammonium salt is used for 1 unit of clay.
  • the studies were performed with a ratio of clay/quaternary ammonium salt of 1/0,3 and 1/0,5 by weight.
  • the pH adjustment was made by the addition of sulfuric acid and then the product was mixed with the agent.
  • the trials were generally started by adding 45 g halloysite to 450 mL purified water, stirring with a mixer for about 15-20 minutes, and thoroughly expanding and homogeneously dispersing the clay in water. After the clay was expanded, the pH adjustment was made by the addition of H2SO4 according to the desired pH value. The excess acid was removed by treating the same with NaOH until the pH value increased to 9.
  • the specimens were modified for 1 hour in a mixer by mixing the same with a given proportion of quaternary ammonium salt at the prescribed temperature. In order to remove the excess of quaternary ammonium salt from the specimens of modified halloysite, the treatment was performed with methanol with a volume numerically equivalent to the mass of the quaternary ammonium salt.
  • the specimens obtained following the methanol addition were pressed in a filter press, the times for draining off the water content was recorded, and the filtered specimens were examined by XRD after being dried in a drying oven.
  • the BET studies were then performed for some selected specimens. The information about the trials is provided in the following table.
  • the modification studies were performed with acid activation and quaternary ammonium salt.
  • the stirring was performed by way of mechanical mixing.
  • the interlayer spaces of 9,9 A and 7,2 A present in the purified halloysite are the characteristic values for metahalloysite and halloysite.
  • the interlayer space of 9,9 A disappeared due to the acid treatment.
  • the results show no change regardless of the modification type, modification temperature and quaternary ammonium salt content. This indicates that the interlayer space that disappears depends only on the presence of acid. Further varying the pH value did not change the result.
  • the interlayer space of 9,9 A disappeared as a result of acid activation, but the 7,2 A interlayer space did not experience damage at all.
  • halloysite may differ in the tube structures or in the modification processes as a result of being subjected to dry or wet grinding. This differentiation was examined in the presence of the agents. In order to examine said difference, a set was wet- and dry-ground and subsequently modified with different proportions of quaternary ammonium salt. As a result of XRD, no differentiation was observed in the surface modification studies performed following the wet and dry grinding. A comparison of the dry/wet grinding with the starting halloysite while the pH is 1,5 (room temperature - clay/quaternary ammonium salt: 1/0,5) is shown in Figure 11.
  • the acid activation is not carried out. Based on the results, it was considered that the quantity of acid used was too much for activation. The crystal structure was impaired due to the acid used. It was found that the activation should be performed with a very small quantity of acid in case of performing acid activation for the modification process.
  • modification process with the quaternary ammonium salt may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • the trials were conducted at three feed and conveyor speeds, namely 10 - 20 - 30 kg/h, with a magnetic field level in the range of 20-80.
  • the trials were conducted using the air cooling and water cooling types such that the magnetron power was 0,75-1,2 kW and the total installed power was 16-45 kW.
  • the microwave frequency was set to 2450 MHz. No problem was detected in the layers and tube cavities of the finished product. In these studies, the overall duration was about 30 minutes at the lowest conveyor belt speed. The optimum drying time was observed to be 7-10 minutes. The output moisture ratio could be reduced down to 0,2%.
  • halloysites are modified with different silanes. Owing to the modification of halloysites with silanes, improvement in the thermal properties, compatibility for the strength increase, increase in the scratch resistance and compatibility for the paint applications may be achieved.
  • the silanes indicated below were preferably employed within the scope of the invention and it is also possible to perform the modification process by working with any silane with vinyl terminal group, amine terminal group or methoxy terminal group.
  • the modification may also be performed by way of dispersion in an alcohol, after sulfuric acid activation or after acetic acid activation.
  • halloysites are enabled to be modified with silanes without using any preliminary process.
  • the studies were conducted within the scope of the invention regarding the modification of halloysites with silanes in the absence of a preliminary process.
  • the modification process was performed by taking 200 ml from the 10% halloysite sample, which was purified with a hydrocyclone and then expanded with water, and by adding silane in 4 different quantities, i.e. 10%, 5%, 2,5% and 1% by weight, respectively. These quantities were determined taking the active silane content also into account.
  • the sludge which was stirred for about 1 hour at 60-70°C after the addition of silane, was allowed to cool down to room temperature and was then washed with methanol in order to remove the silane molecules not adhered to the surface.
  • the washed sample was filtered in a filter press and the filtration times were noted as they could be an indicator of the success of the modification process.
  • the filtered samples were dried in a vacuum drying oven for 1 night at maximum 65°C and were brought into a state suitable for surface characterization by means of sample preparation processes. pThe samples subjected to modification are given in the following table.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • halloysites are enabled to be modified with silanes after dispersing a silane in an alcohol.
  • T1 • mixing halloysite and 1-15% by weight silane for 45-95 minutes at a temperature of 50- 80°C,
  • modification process with silane dispersed in alcohol may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • halloysite is enabled to be modified with silane after activation with sulfuric acid.
  • the studies were performed within the scope of the invention about modifying halloysites with silanes after the activation of halloysite with sulfuric acid and thus being able to increase the surface area of halloysite and enabling halloysite to be bound by more agent.
  • the acid used in the activation process reacts with the iron in the structure of halloysite to enable the same to be removed from the structure, which in turn increases the surface area of halloysite and provides the possibility for the binding of more agent to the surface.
  • the process of modifying with silane the halloysite that is activated with sulfuric acid may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave. The drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • halloysite is enabled to be modified with silane after activation with acetic acid.
  • the studies were performed within the scope of the invention regarding the modification of halloysite with silane after the activation of halloysite with acetic acid.
  • Silane is not able to become immediately integrated in the system when it is added to the medium, which in turn may impair homogeneity by causing partial gelation.
  • it is aimed to reduce the pH of the solution to 3, 0-4, 5 by the use of an organic acid such as acetic acid to thereby enable the reinforced material to reach the optimum performance.
  • the acidic medium assists with the stability of silane and enables silane to be more stable and more easily oriented on the surfaces where it is bound.
  • acetic acid CH3COOH
  • acetic acid was used to examine the effect of the acid used and the pH of the medium. This process was performed by bringing 200 ml halloysite to 25°C and adding the acid until the pH value became 3-4,5. Following the acid addition, the steps of adding silane, stirring for 1 hour at 60-70°C, washing with methanol, filtering and drying were carried out and the samples were prepared for surface characterization.
  • the process of modifying with silane the halloysite that is activated with acetic acid may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave. The drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • the halloysite nanotubes are the minerals containing voids 30-40 nm in diameter.
  • the trials were performed within the scope of the study to fill in these voids or modify the surfaces with various agents.
  • the appropriate dimensions for halloysite were determined. While the surface area of the halloysite blend product was found as 79 m 2 /g, this value rose to 130 m 2 /g after the purification studies with hydrocyclone and to 116 m 2 /g after the purification studies by centrifugation.
  • the surface area values are expected to decrease in case the tube interiors are filled as a result of modifications performed with silane.
  • Table 15 shows the variations in the surface area of halloysite modified by four different methods, according to the quantity of silane.
  • the different surface area values are obtained due to the difference in the chain lengths. While greater surface area values are obtained with silane having vinyl benzyl amino group, smaller surface area values are found with octyltrimethoxy silane. According to the chemical contents, it is considered that the second silane type penetrates the system to a greater extent.
  • XRD patterns following the addition of vinylbenzylaminoethylaminopropyltrimethoxy silane (Silane A) and acetic acid and modification are shown in Figure 22, and XRD patterns following the addition of n-octyltrimethoxy silane (Silane B) and acetic acid and modification are shown in Figure 23.
  • the presence of the peaks 15 A and 7,40 A was also detected as a result of the studies performed with acetic acid.
  • the 10 A peaks were not observed either in these results similar to the trials performed with sulfuric acid.
  • the interlayer space values (d) of 10 A and 7,40 A of halloysite show the shifting tendency after the processes.
  • the halloysite peaks of 10 A increase to the level of 15 A, while the 7,40 A peaks are preserved.
  • the intensity of the 15 A peak increases with increasing silane quantity. For the additions of 1% by weight where the silane quantity is the lowest, all of the interlayer space values of 15 A, 10 A and 7,40 A are observed.
  • silane increases the interlayer space values of the halloysite nanotubes and expands the spaces.
  • a preliminary process i.e. when various chemicals like alcohol and acid are added, the surface area increases and the peaks remain the same. It was considered that this could result from the damage the dispersing medium causes in silane as well as the expansion of the tubular structure and the increase of the surface area due to the increase in the interlayer space value. Accordingly, it is thought that the surface area values and the filtration times could likewise increase.
  • a SEM study was conducted in order to clarify this. The images of the morphological analysis performed with the products with 1% agent addition are shown in Figures 25 and 26.
  • the diametric widths generally in the range of 60-100 nm were measured, which is in parallel with the starting halloysites.
  • halloysites are enabled to be modified with thermal agents.
  • Said thermal agents are polyethylene glycol (PEG) 600, polyethylene glycol (PEG) 1000, eicosane (C20H42) or octadecane (CisHss). Thermal camouflage may be achieved by the use of these agents.
  • the studies were performed within the scope of the invention regarding the modification of halloysites with thermal agents in the absence of a preliminary process. Table 17. Thermal agent testing set
  • the modification process was performed with a phase shifter material.
  • Eicosane and PEG 1000 are in solid form, while PEG 600 and octadecane are in liquid form.
  • the solid agents with melting point above the room temperature were first brought into the liquid state by way of dissolving the same in a water bath and were added to the process at the ratios of 10%, 5%, 2,5% and 1% by weight.
  • eicosane further trials were conducted with a ratio of 0,5% by weight at 60-70°C.
  • the washed samples were filtered in the filter press and the filtration times were noted as these could be an indicator for the success of the modification process.
  • the filtered samples were dried for 1 night in a vacuum drying oven at 65°C and were rendered suitable for the surface characterization by way of sample preparation processes.
  • While the process of modifying halloysite with a thermal agent may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • the surface area, filtration times and interlayer space values were observed with a comparative approach. Table 18. Effect of the quantity and type of thermal agent on the surface area and filtration time
  • the surface area tends to decrease with increasing silane quantity. However, no significant difference was observed in the surface area values when the agents PEG 600 and PEG 1000 were used. On the other hand, based on the filtration time values, the products with PEG 1000 content were determined to be filtered in shorter time. The surface area values turned out quite low as a result of the studies performed with the agent eicosane. The surface area value, which was 130 m 2 /g after the purification, dropped to the levels of 40-75 m 2 /g when modified with this product. It is considered that it is easier for this product to penetrate the halloysite nanotubes.
  • the morphological study was performed for the samples with 1% thermal agent content. As can be seen from the SEM images, the tube structures were not impaired, but their lengths decreased. The tube lengths are generally 200-400 nm. It is considered that the diametric widths also changed. It was found that the diameter increases occurred and the dimensions were in the range of about 90-100 nm. The width increases are remarkable especially in the PEG 1000 sample. This provides an information parallel to the XRD results. The increases were also detected in the tube diameters, upon the interlayer space values (d) of normally 10 A shifting to the value of 15 A when the agent was started to be filled in the tubes. This explains the changes in the surface area values.
  • the trial with the agent octadecane was also performed in addition to the above-mentioned trials with PEG 600, PEG 1000 and eicosane.
  • the surface area values decreased as compared to the surface area of the starting halloysite mineral, as expected. It was thought that the reason for this was the adherence of the surface modification agent to the active surfaces of halloysite, as was the case with the trials with silane, and this was considered as a favorable result.
  • the surface area tends to decrease with increasing octadecane quantity. While the surface area of the starting mineral (purified halloysite) was 130 m 2 /g, the surface area was observed to drop down to as low as 24,68 m 2 /g following the surface modification. According to these results, it was determined that the surface of the starting mineral, i.e. the purified halloysite, could be coated by an extent in the range of 44-82%.
  • the filtration times are also an evaluation criterion for the success of the modification process.
  • the hydrophilic halloysite mineral acquires the hydrophobic character owing to the agents adhering to the surface.
  • the filtration times for the hydrophobic modified halloysite are expected to be shorter than the filtration time for the starting mineral.
  • no difference providing superiority of one quantity over the others was observed in the filtration times.
  • the results of variation in the interlayer space values when using octadecane are given in Figure 31.
  • the peaks of 10 A When the XRD graph in the figure was examined, the peaks of 10 A, one of the characteristic peaks of halloysite, were observed to disappear as a result of heat treatment.
  • the peaks of 7 A another characteristic peak, expanded to 7,56-7,66 A.
  • the quantity of octadecane is insufficient to increase the interlayer space value in the trials performed with the addition of 1%, 2,5% and 5% octadecane, it is considered that the quantity of the agent penetrating the structure increases in parallel with the increase in the quantity of the agent and thus raises the 7 A peak to the level of 15,21 A in the trials performed with the addition of 10% agent.
  • the starting halloysite mineral has a length of about 1,2 microns, an outer diameter of 40 nm and an inner diameter of 20 nm. The change in the tubes compared to this starting halloysite was examined.
  • the tube length of halloysite modified by the use of 1% PEG 600 is around 200-400 nm.
  • the tubes were observed to break and became shorter than the starting mineral.
  • the average outer diameter is 82 nm and inner diameter is 41 nm.
  • the nanotube width of halloysite approximately doubled. This expansion also supports the XRD graphs.
  • the tubes broke as a result of the modification by the addition of 1% eicosane, as in the modifications with the other thermal agents, and the tube lengths varied in the range of 200-300 nm.
  • the value is around 50 nm and an increase of 25% is present relative to the purified halloysite.
  • the inner diameter is around 10 nm and decreased by 50% compared to the starting mineral.
  • the morphological image (SEM) following the addition of 1% octadecane is shown in Figure 35
  • the morphological image (SEM) following the addition of 10% octadecane is shown in Figure 36
  • the morphological image (TEM) following the addition of 1% octadecane is shown in Figure 37
  • the morphological image (TEM) following the addition of 10% octadecane is shown in Figure 38.
  • the outer diameter of the tubes the value is around 50 nm; the inner diameter is around 15-20 nm and similar to the starting mineral.
  • the diameter increases were observed although there was no change in the tube lengths.
  • the outer diameter increased to 60 nm and the inner diameter increased to 20-25 nm. This is an indication of the increase in the diameters and the increase in the interlayer space when more agent is introduced to the tubes. This result is consistent with the values of d obtained in XRD.
  • halloysites are enabled to be modified with anticorrosive agents, preferably benzotriazole (C6H5N3).
  • anticorrosive agents preferably benzotriazole (C6H5N3).
  • the anticorrosive action may be achieved following the modification with benzotriazole.
  • While the process of modifying halloysite with benzotriazole may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • halloysites are enabled to be modified with silanized quaternary salt.
  • silanized quaternary salt is an organosilane quaternary amine product. The antimicrobial action may be achieved following the modification of halloysites with silanized quaternary salt.
  • While the process of modifying halloysite with silanized quaternary salt may be performed under a pressure of 1,5-2, 5 bars, it is also possible to realize the process without applying extra pressure.
  • the filtration process is performed preferably in a filter press or by way of holding and draining.
  • the drying process is performed preferably in a fan drying oven or a vacuum drying oven or using microwave.
  • the drying in a fan drying oven and in a vacuum drying oven is realized for 12-24 hours at a maximum temperature of 60-70°C, while the drying by the use of microwave is performed for 5-70 minutes.
  • the halloysites modified with quaternary ammonium salts and/or silanes may be used in the automotive and cable industries for a surface compatible with PP (polypropylene) and PE (polyethylene), the halloysites modified with thermal agents may be used for the acrylic fiber (polyacrylonitrile) applications, the halloysites modified with anticorrosive agents may be used in the paint and marine applications, and the halloysites modified with silanized quaternary salts may be used in every field where antimicrobial action is desired.
  • PP polypropylene
  • PE polyethylene
  • the halloysites modified with thermal agents may be used for the acrylic fiber (polyacrylonitrile) applications
  • the halloysites modified with anticorrosive agents may be used in the paint and marine applications
  • the halloysites modified with silanized quaternary salts may be used in every field where antimicrobial action is desired.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)

Abstract

L'invention se rapporte à un halloysite modifié qui est modifié et doté de propriétés fonctionnelles sans endommager les teneurs en nanotubes et à un procédé de modification pour obtenir ledit halloysite modifié. Plus particulièrement, l'invention se rapporte à un halloysite modifié, qui est purifié et rendu ouvert à une liaison de surface et qui est doté de propriétés fonctionnelles en étant modifié avec différents agents de telle sorte que sa teneur en nanotubes soit préservée et que sa structure physique et morphologique ne soit pas endommagée, et à un procédé de production dudit halloysite.
EP21856360.9A 2020-08-14 2021-07-30 Procédé de modification du minéral halloysite et halloysite modifié par le biais du procédé de modification Pending EP4196441A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
TR2020/12812A TR202012812A2 (tr) 2020-08-14 2020-08-14 Halloysi̇t mi̇nerali̇ni̇n modi̇fi̇kasyon yöntemi̇ ve modi̇fi̇kasyon yöntemi̇ i̇le modi̇fi̇ye edi̇lmi̇ş halloysi̇t
PCT/TR2021/050756 WO2022035399A2 (fr) 2020-08-14 2021-07-30 Procédé de modification du minéral halloysite et halloysite modifié par le biais du procédé de modification

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