KR102506522B1 - Manufacturing method for polyvinyl acetal brush - Google Patents

Abstract

The present invention relates to a method for manufacturing a polyvinyl acetal brush.
A method for producing a polyvinyl acetal brush according to an embodiment of the present invention includes the steps of adding a pore forming agent to a polyvinyl alcohol (PVA) mixture to create a mixture; Injecting the mixture into a mold and aging to produce a hollow molding; demolding the molding from the mold; washing the molded article with a first cleaning solution to remove the pore-forming agent; Cutting the molded article into a predetermined size; washing the cut molded article with a second cleaning solution to remove residual pore-forming agent; inserting a core into the hollow of the cut molding; dewatering the molded article into which the core is inserted at high speed to remove residual pore-forming agent; and preserving the molded article into which the core is inserted.

Description

Manufacturing method of polyvinyl acetal brush {Manufacturing method for polyvinyl acetal brush}

The present invention relates to a method for manufacturing a polyvinyl acetal brush.

Polyvinyl acetal is water obtained through acetalization of polyvinyl alcohol (PVA) and aldehydes. Polyvinyl acetal has excellent durability and chemical resistance, and is used as a sponge in various industrial fields due to its high absorbency. Due to these characteristics, it has been used as a cleaning brush in the process of cleaning semiconductor substrates and display substrates in the manufacture of semiconductors and displays.

In general, a method for producing a polyvinyl acetal brush is to mix polyvinyl alcohol, which is a raw material, with water and heat to obtain a polyvinyl alcohol aqueous solution, mix a pore former and an aldehyde with the aqueous solution, and then inject into a mold and heat After acetalization, it is separated from the mold and cut according to the purpose.

Conventional polyvinyl acetal brushes have problems such as occurrence of defects due to high content of impurities such as pore formers and metal ions.

Korean Patent Publication No. 10-2019-0033339, which is a prior art document, discloses a technique for removing impurities in a PVA brush.

Korean Patent Publication No. 10-2019-0033339

An object of the present invention is to provide a method for manufacturing a polyvinyl acetal brush capable of effectively removing impurities such as a pore forming agent.

A method for producing a polyvinyl acetal brush according to an embodiment of the present invention includes the steps of adding a pore forming agent to a polyvinyl alcohol (PVA) mixture to create a mixture; Injecting the mixture into a mold and aging to produce a hollow molding; demolding the molding from the mold; washing the molded article with a first cleaning solution to remove the pore-forming agent; Cutting the molded article into a predetermined size; washing the cut molded article with a second cleaning solution to remove residual pore-forming agent; inserting a core into the hollow of the cut molding; dewatering the molded article into which the core is inserted at high speed to remove residual pore-forming agent; and preserving the molded article into which the core is inserted.

In the step of washing the demolded molding with a first cleaning solution to remove the pore-forming agent, the first cleaning solution may be any one of H ₂ SO ₄ and HF.

In the step of washing the cut molding with a second cleaning solution to remove residual pore-forming agent, the second cleaning solution may be any one of H ₂ SO ₄ and HF.

After the step of demolding the molded article from the mold, a step of removing residual PVA debris by washing the demolded molded article with a third cleaning solution may be further included.

After the step of cutting the molded article into a predetermined size, a step of removing residual metal ions by washing the cut molded article with a fourth cleaning solution may be further included.

After the step of cutting the molded product into a predetermined size, a step of removing any one of negative ions and particles having negative zeta potential by washing the cut molded product with a fifth cleaning solution may be further included.

After the step of cutting the molded product into a predetermined size, a step of removing residual PVA debris by washing the cut molded product with a third cleaning solution may be further included.

A step of polishing a surface of the molded article may be further included after the step of washing the demolded molded article with a first cleaning solution to remove the pore forming agent.

The method for manufacturing a polyvinyl acetal brush according to an embodiment of the present invention can effectively remove impurities such as a pore forming agent.

1 is a flow chart of a method for manufacturing a polyvinyl acetal brush according to an embodiment of the present invention.
2 is a photograph of a polyvinyl acetal brush prepared according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. "Including" a component throughout the specification means that other components may be further included without excluding other components unless otherwise stated.

A method for producing a polyvinyl acetal brush according to an embodiment of the present invention includes the steps of adding a pore forming agent to a polyvinyl alcohol (PVA) mixture to create a mixture; Injecting the mixture into a mold and aging to produce a hollow molding; demolding the molding from the mold; washing the molded article with a first cleaning solution to remove the pore-forming agent; Cutting the molded article into a predetermined size; washing the cut molded article with a second cleaning solution to remove residual pore-forming agent; inserting a core into the hollow of the cut molding; dehydrating the molded article into which the core is inserted at high speed to remove residual pore-forming agent; and preserving the molded article into which the core is inserted.

The step of adding a pore-forming agent to the polyvinyl alcohol (PVA) mixture to create a mixture may include adding a pore-forming agent to the polyvinyl alcohol (PVA) mixture and adding an aldehyde thereto, A step of adding an acid may be further included. Specifically, this step includes forming a first mixture by mixing and heating water and polyvinyl alcohol (PVA), forming a second mixture by adding a pore-forming agent to the first mixture, and forming a third mixture by adding an aldehyde and an acid to the second mixture.

In the step of mixing the water and polyvinyl alcohol to form the first mixture, the polyvinyl alcohol may be included in an amount of 5 to 20 parts by weight based on 100 parts by weight of water. Polyvinyl alcohol can be mixed well within the above content range, has high elasticity and tensile strength, excellent chemical resistance, and can produce a polyvinyl acetal brush that does not generate static electricity, fibers, or dust. In this step, the heating temperature may be 90 °C or higher, preferably 90 to 100 °C. By heating in this temperature range, polyvinyl alcohol can be well dissolved in water without deteriorating its properties.

In the step of adding the pore-forming agent to the first mixture to form the second mixture, 2 to 10 parts by weight of the pore-forming agent may be added with respect to 100 parts by weight of the first mixture. In the above content range, the role of the pore former can be maximized to increase pores, and a polyvinyl acetal brush with excellent cleaning power can be made. Potato starch or corn starch may be used as the pore former in this step, and the number or size of pores may vary depending on the type of pore former. In this step, the second mixture may be cooled to 30 to 40°C. Through this, the next step, the acetalization reaction, can be prepared to occur effectively.

In the step of forming a third mixture by adding an aldehyde and an acid to the second mixture, 7 to 15 parts by weight of an aldehyde and 7 to 15 parts by weight of an acid may be added to 100 parts by weight of the second mixture. Stirring may be performed for mixing, and the stirring time may be 10 minutes to 60 minutes, preferably 30 minutes. Polyvinyl acetal is produced as a chemical reaction occurs between polyvinyl alcohol and aldehyde dissolved in the second mixture. The chemical reaction is a reversible reaction, and the forward reaction and the reverse reaction chemically proceed simultaneously. Therefore, in order to suppress the reverse reaction and induce the forward reaction, aldehyde as a pre-reaction material may be added. The acid functions as a catalyst that promotes a forward reaction for the reversible reaction of forming the polyvinyl acetal. The acid is not particularly limited as long as it is used as a catalyst in the acetalization reaction.

Next, a step of injecting the mixture into a mold and aging it to produce a hollow molding is performed.

The mold is a mold for repeatedly producing the same type of polyvinyl acetal brush and may be made of a polymeric material, ceramic or metal. The mold may include overlapping at least two hollow molds to form the hollow and protrusion of the brush, and may include a plurality of intaglio or embossed shapes at regular intervals.

It may be preferable to inject the mixture while maintaining stirring using a mixer or the like until the mixture is injected into the mold. The reason is that the components constituting the fifth mixture are maintained uniformly as a whole.

A mold into which the mixture is injected may be placed in an oven and heated and matured to form a molded article. The temperature of the oven into which the mold into which the mixture is injected may be 40 to 80 °C. The number of defective products in which a part of the molded article formed in the above temperature range is torn, punctured, burnt, or discolored may be minimized. The reason for aging is to turn a liquid mixture into a solid state.

Next, a step of demolding the molding from the mold may be performed, and a washing and dehydration process may be additionally performed. Unreacted aldehyde and acid may be eluted through the washing and dehydration process.

After the step of demolding the molded article from the mold, a step of removing residual PVA debris by washing the demolded molded article with a third cleaning solution may be further included. The third cleaning solution may be isopropyl alcohol (IPA). In this process, cleaning may be performed by immersing the molding in a bathtub containing IPA, and cleaning may be performed by spraying IPA from the outside.

The step of removing the pore-forming agent by washing the demolded molding with a first cleaning solution may be performed. If the pore-forming agent remains on the brush, the pore-forming agent escapes from the brush during the semiconductor and display cleaning process, thereby contaminating the semiconductor and display substrates to be cleaned. In addition, the pore forming agent may cause deterioration of physical properties of the brush by blocking pores. This problem can be prevented by removing the pore former through an acid at this stage.

The first cleaning liquid may be any one of H ₂ SO ₄ and HF. This step may include impregnating the molded article in a low-concentration diluted acidic aqueous solution (first cleaning solution) and dehydrating and washing the molded article. Pore forming agents such as potato starch may be removed from the low-concentration acidic aqueous solution. If the acid concentration is high in the acidic aqueous solution, damage such as holes or discoloration may occur in the molding. The impregnation time in this step may be 1 to 3 hours. If the impregnation time is less than 1 hour, the effect of removing the pore-forming agent is reduced. If the impregnation time exceeds 3 hours, problems such as holes or discoloration may occur in the molding. can

Next, a step of cutting the molding into a predetermined size is performed. This step can be performed with a rotary saw blade or a cutter with a moving blade.

In another embodiment, after the step of washing the demolded molded article with a first cleaning solution to remove the pore-forming agent, the step of polishing the surface of the molded article may be further included. It can be performed when the surface condition of the molded object released from the mold is uneven or the size of the protrusion is not constant, and a brush with a certain size, elasticity, porosity, and flatness can be manufactured through this step. This step may be performed using an abrasive with an abrasive stone or pad.

Next, a step of removing the residual pore-forming agent by washing the cut molded article with a second cleaning solution may be performed. Since the molding was previously cut to a certain size, the pore-forming agent can be more effectively removed through the cut portion. In addition, if surface polishing is performed, the pore-forming agent can be more effectively removed through the polished surface. In this step, the second cleaning liquid may be any one of H ₂ SO ₄ and HF. This step may be performed using a cleaner having a bath in which a rotary shaft and a spray of cleaning liquid are disposed. Cleaning may be performed by inserting the hollow of the molded object into the rotating shaft to rotate the molded object, and spraying a second cleaning solution on the surface of the molded object through the washer sprayer. When the pore-forming agent is sufficiently removed through the second cleaning solution, the second cleaning solution may be removed by spraying washing water. In addition, the second cleaning liquid and washing water inside the molding can be removed through dehydration.

In one embodiment, after the step of cutting the molded object to a certain size, the step of removing residual metal ions by washing the cut molded object with a fourth cleaning solution may be further included. The fourth cleaning liquid may be HCL, and may dissolve and remove metal ions such as Fe, Al, and Cu. Since these metal ions are impurities that cause defects in the manufacture of semiconductors and displays, contamination by brushes can be prevented by performing this step. This step may be performed using the previously described scrubber. After this step, the washing and dehydration process may be performed at least once to remove the fourth washing liquid.

In one embodiment, after the step of cutting the molded object to a certain size, the step of removing any one of negative ions and particles having negative zeta potential by washing the cut molded object with a fifth cleaning solution may be further included. The fifth cleaning liquid may be NH ₄ OH. Like metal ions, the negative ion is an impurity that causes defects in the manufacture of semiconductors and displays. By performing this step, contamination by the brush can be prevented. This step may be performed using the previously described scrubber. After this step, the washing and dehydration process may be performed at least once to remove the fifth washing liquid.

In one embodiment, after the step of cutting the molded product to a certain size, the step of removing residual PVA debris by washing the cut molded product with a third cleaning solution may be further included. The third cleaning liquid may be IPA. Since the PVA crumb is an impurity that causes defects in the manufacture of semiconductors and displays, contamination by the brush can be prevented by performing this step. This step may be performed using the previously described scrubber. After this step, the washing and dehydration process may be performed at least once to remove the third washing liquid.

A step of inserting a core into the hollow of the cut molding may be performed. The core may be made of a polymer material or ceramic material having corrosion resistance, and may have a cylindrical or polygonal column shape so that it can be inserted into the hollow of the molding. In addition, by having a plurality of holes on the surface, the washing liquid or washing water can be supplied to the inside of the core so that the washing liquid or washing water can be supplied to the brush through the holes.

Next, a step of removing the residual pore-forming agent by dewatering the molded article into which the core is inserted is performed by rotating at high speed.

In this step, the polyvinyl acetal brush is rotated about one axis, and the pore-forming agent inside the polyvinyl acetal brush can be discharged to the outside through centrifugal force. Since the molded body is supported by the core, it can be rotated at a higher speed, so the effect of discharging impurities using centrifugal force can be greatly improved. For this purpose, a high-speed dehydrator including a plurality of poles rotating around one axis may be used. By inserting cores of polyvinyl acetal brushes into the plurality of poles and rotating the high-speed dehydrator around one axis, the plurality of polyvinyl acetal brushes can be efficiently dewatered. Also, the plurality of poles may rotate about their respective centers. Through this case, the polyvinyl acetal brush rotates around the pole and at the same time rotates around one axis of the high-speed dehydrator, so the dehydration efficiency can be increased, and the pore forming agent inside the polyvinyl acetal brush can be discharged to the outside. .

In this step, the first cleaning liquid may be sprayed onto the surface of the molded article rotating in the high-speed dehydrator. Through this, the pore-forming agent can be more effectively removed.

The step of preserving the molded article into which the core is inserted may be performed before or after the step of removing the residual pore forming agent by dewatering the molded article into which the core is inserted at high speed. More preferably, it is possible to prevent excessive removal of the preservative solution by dehydration by performing dehydration by rotating the molded article into which the core is inserted at high speed to remove the residual pore-forming agent. The antiseptic solution may be at least one of an isothiazolone compound, glutaraldehyde and a quaternary ammonium compound, and is not particularly limited.

Manufacture of polyvinyl acetal brush

2 is a photograph of a polyvinyl acetal brush prepared according to an embodiment of the present invention. The polyvinyl acetal brush is manufactured by the following method.

10 parts by weight of PVA powder was added to 100 parts by weight of DIW, and the mixture was heated and stirred at 95° C. to dissolve PVA in DIW. Thereafter, 5 parts by weight of potato starch as a pore forming agent was added to 100 parts by weight of the PVA mixture, and then cooled to 40 ° C. Then, 10 parts by weight of aldehyde and 10 parts by weight of acid were added to 100 parts by weight of the above mixture and stirred. The mixture was put into a mold and the mold was aged at 60° C. for 15 hours in an oven. Thereafter, the molded article was demolded from the mold, washed by immersion in HF, and washing and dehydration were repeated. Next, the molding was cut into a certain size, washed by spraying HF, and washing and dehydration were repeated. Next, a cylindrical core was inserted into the hollow of the molded body, dehydrated with a high-speed dehydrator, and preserved.

Experiment example

In order to demonstrate the effect of the embodiment of the present invention, when the dehydration process was performed using a general dehydrator and a high-speed dehydrator, the number of particles was compared and listed in Table 1. The manufacturing method of the molded body was performed in the same manner as the manufacturing of the polyvinyl acetal brush described above, but the dehydration process was performed and preservative treatment was not performed. In addition, in the case of the embodiment, dehydration was performed while spraying HF as the first cleaning liquid from the outside while rotating after fixing the core of the molded body on a pole using a high-speed dehydrator, and in the comparative example, inside the rotating cylinder Dehydration is carried out using a general dehydrator that dehydrates the molded body by rotating the cylinder. The number of particles was analyzed by using a liquid particle counter (LPC) for the liquid extracted from the molded body after the dehydration process was completed.

Dehydration time (hr) Comparative Example: Normal Dehydrator Particle Count (LPC) Example: High Speed Dehydrator Particle Count (LPC) 3 1083 298 6 1064 189

Referring to the results in Table 1, it can be seen that when a high-speed dehydrator is used, a large number of internal pore formers are discharged, resulting in an excellent particle reduction effect.

Claims (8)

adding a pore forming agent to a polyvinyl alcohol (PVA) mixture to create a mixture;
Injecting the mixture into a mold and aging to produce a hollow molding;
demolding the molding from the mold;
washing the molded article with a first cleaning solution to remove the pore-forming agent;
Cutting the molded article into a predetermined size;
The cut molding is washed with a second cleaning solution, and through the cut portion of the molding removing residual pore former;
inserting a core into the hollow of the cut molding;
On the pole of a high-speed dehydrator including a plurality of poles Insert the molding into which the core is inserted, centering on the core removing residual pore-forming agent by high-speed rotation; and
Including, preservative treatment of the molded article into which the core is inserted.
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
In the step of washing the demolded molding with a first cleaning solution to remove the pore former,
The first cleaning solution is any one of H ₂ SO ₄ and HF,
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
In the step of washing the cut molding with a second cleaning solution to remove residual pore-forming agent,
The second cleaning liquid is any one of H ₂ SO ₄ and HF,
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
After the step of demolding the molding from the mold,
Further comprising the step of cleaning the demolded molding with a third cleaning solution to remove residual PVA debris,
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
After the step of cutting the molding to a certain size,
The cut molding is HCl removing residual metal ions by washing with a fourth cleaning solution;
washing the cut molding with a fifth cleaning solution of NH ₄ OH to remove any one of negative ions and particles having negative zeta potential; and
Further comprising the step of removing the fourth and fifth washing liquids,
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
The step of removing the residual pore-forming agent by rotating at high speed includes spraying the first cleaning solution on the surface of the rotating molded body.
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
After the step of cutting the molding to a certain size,
Further comprising the step of cleaning the cut molding with a third cleaning solution to remove residual PVA debris,
Manufacturing method of polyvinyl acetal brush.
According to claim 1,
After the step of washing the demolded molding with a first cleaning solution to remove the pore-forming agent,
Further comprising polishing the surface of the molding,
Manufacturing method of polyvinyl acetal brush.

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