阅读说明：本技术 清洁用部件及其制造方法 (Cleaning member and method for manufacturing same ) 是由 东城武彦 植松武彦 铃木真彦 于 2020-02-25 设计创作，主要内容包括：本发明的清洁用部件(1)具有通过中值纤维直径为100nm以上且2000nm以下的单纤维的缠绕而保形的无纺结构体(2)。无纺结构体(2)的表观密度为0.05g/cm～(3)以上且0.60g/cm～(3)以下。清洁用部件(1)也优选还具有支承部件(3),支承部件(3)与无纺结构体(2)以彼此接触的方式配置。还优选单纤维为静电纺丝而成的纤维。另外,本发明的清洁用部件的制造方法包括通过静电纺丝法进行纺丝而形成单纤维的堆积体的步骤；和对该堆积体进行按压而形成表观密度为0.05g/cm～(3)以上且0.60g/cm～(3)以下的无纺结构体的步骤。(The cleaning member (1) has a nonwoven structure (2) that is formed by winding single fibers having a median fiber diameter of 100nm to 2000 nm. The apparent density of the nonwoven structure (2) was 0.05g/cm 3 Above and 0.60g/cm 3 The following. The cleaning member (1) also preferably further comprises a support member (3), and the support member (3) and the nonwoven structure (2) are preferably arranged to be in contact with each otherThe contact is configured. The single fibers are preferably electrospun fibers. The method for manufacturing a cleaning member of the present invention includes a step of forming a deposit of single fibers by electrospinning; and pressing the stacked body to form a bulk density of 0.05g/cm 3 Above and 0.60g/cm 3 The following steps of the nonwoven structure.)

1. A cleaning member, characterized in that:

has a nonwoven structure which is formed by winding single fibers having a median fiber diameter of 100nm to 2000nm,

the non-woven knotThe apparent density of the structure was 0.05g/cm³Above and 0.60g/cm³The following.

2. The cleaning member according to claim 1, wherein:

the nonwoven structure has a void ratio of 30% to 75%,

the pore volume distribution obtained by differentiating the cumulative pore volume by the logarithmic value of the pore diameter has a distribution having a peak in the pore diameter range of 50 μm or less and no peak in the pore diameter range exceeding 50 μm.

3. The cleaning member according to claim 1 or 2, characterized in that:

the nonwoven structure is a compression-molded body of a stacked body in which the single fibers are wound.

4. The cleaning member according to any one of claims 1 to 3, characterized in that:

and a supporting component is also arranged on the bracket,

the support member and the nonwoven structure are arranged so as to be in contact with each other.

5. The cleaning member according to claim 4, wherein:

the nonwoven structure is disposed so as to cover the entire surface of the support member.

6. The cleaning member according to claim 4, wherein:

the sheet-like or block-like nonwoven structure is disposed on at least one surface of the plate-like support member.

7. The cleaning member according to claim 4, wherein:

the sheet-like nonwoven structure is disposed on the circumferential surface of the cylindrical support member.

8. The cleaning member according to any one of claims 1 to 7, characterized in that:

the nonwoven structure is in the form of a sheet, and the penetration time of water droplets into the nonwoven structure is within 1 minute.

9. The cleaning member according to any one of claims 1 to 8, characterized in that:

the nonwoven structure is in the form of a sheet, and the water droplets penetrate the nonwoven structure for 40 seconds or less.

10. The cleaning member according to any one of claims 1 to 9, characterized in that:

the single fibers are fibers obtained by electrostatic spinning.

11. The cleaning member according to any one of claims 1 to 10, characterized in that:

the filaments comprise a thermoplastic resin and are formed from a thermoplastic resin,

The thermoplastic resin is polyolefin resin of polyethylene, polypropylene, ethylene-alpha-olefin copolymer and ethylene-propylene copolymer; polyester resins of polyethylene terephthalate; polyamide resins of polyamide 6 and polyamide 66; vinyl resins of polyvinyl chloride and polystyrene; and at least one of acrylic resins of polyacrylic acid and polymethyl methacrylate.

12. The cleaning member according to claim 11, wherein:

the content of the thermoplastic resin is 70 parts by mass or more and 98 parts by mass or less with respect to 100 parts by mass of all the constituent components of the single fiber.

13. The cleaning member according to any one of claims 1 to 12, characterized in that:

the filaments comprise an ionic surfactant.

14. The cleaning member according to claim 13, wherein:

the content of the ionic surfactant is 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of all the components of the single fibers.

15. The cleaning member according to any one of claims 1 to 14, characterized in that:

the apparent density of the nonwoven structure is 0.10g/cm³Above and 0.55g/cm ³The following.

16. The cleaning member according to any one of claims 1 to 15, characterized in that:

the nonwoven structure has a void ratio of 40% to 70%.

17. The cleaning member according to any one of claims 1 to 16, characterized in that:

the cumulative pore volume of the nonwoven structure is 0.8mL/g to 20 mL/g.

18. A method for manufacturing a cleaning member according to any one of claims 1 to 17, comprising:

a step of ejecting a solution or a melt of the composition for electrospinning into an electric field, and spinning the composition by an electrospinning method to form a deposit of single fibers; and

pressing the stacked body to form a bulk density of 0.05g/cm³Above and 0.60g/cm³The following steps of the nonwoven structure.

19. The method for manufacturing a cleaning member according to claim 18, wherein:

applying 10N/cm to the stack²Above 100000N/cm²The nonwoven structure as a compression-molded body was formed under the following pressure.

20. The method for manufacturing a cleaning member according to claim 18, wherein:

the stacked body is introduced between a pair of press rollers to form a sheet-like or plate-like nonwoven structure.

21. The method for manufacturing a cleaning member according to any one of claims 18 to 20, characterized in that:

the cleaning member is provided with the nonwoven structure and the support member, and is formed by any one of a step of covering the outer surface of the support member with the nonwoven structure in a sheet form, a step of laminating the nonwoven structure in a sheet form or a plate form with the support member, and a step of winding the nonwoven structure in a sheet form around the outer surface of the support member.

22. The method for manufacturing a cleaning member according to any one of claims 18 to 21, characterized in that:

and heating the nonwoven structure.

23. The method for manufacturing a cleaning member according to any one of claims 18 to 22, characterized in that:

spinning by an electrospinning method using the composition for electrospinning comprising a resin to form a deposit of single fibers comprising the resin,

pressing the stacked body to form a bulk density of 0.05g/cm³Above and 0.60g/cm³The following non-woven structure is described,

the nonwoven structure is subjected to a heat treatment at a temperature not exceeding the melting point or flow point of the resin.

Technical Field

The present invention relates to a cleaning member and a method for manufacturing the same.

Background

In recent years, ultrafine fibers having a diameter of several μm or less have been used in various applications in the form of a fiber aggregate obtained by interlacing the fibers. For example, patent document 1 discloses a cleaning cloth made of a nonwoven fabric formed by winding bundles of ultrafine fibers and/or ultrafine fibers, each of which has a number average diameter of 1 to 400nm and in which the weight ratio of single fibers having diameters of 1 to 400nm is 60% or more among all the ultrafine fibers. This document also discloses that the cleaning cloth has a dense structure and can be used for cleaning a substrate for a magnetic storage medium.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2008-55411

Disclosure of Invention

The present invention relates to a cleaning member.

In one embodiment, the cleaning member has a nonwoven structure which is formed by winding single fibers having a median fiber diameter of 100nm or more and 2000nm or less.

In one embodiment, the nonwoven structure has an apparent density of 0.05g/cm³Above and 0.60g/cm³The following.

The present invention also relates to a method for manufacturing the cleaning member.

In one embodiment, the above-mentioned production method comprises a step of ejecting a solution or a melt of the composition for electrospinning into an electric field and spinning the composition by an electrospinning method to form a deposit of single fibers.

In one embodiment, the method of manufacturing includes pressing the stacked body to form the stacked body having a density of 0.05g/cm³Above and 0.60g/cm³The following steps of the nonwoven structure.

Drawings

Fig. 1 (a) is a schematic view showing a state in which single fibers contained in a nonwoven structure provided in a cleaning member of the present invention are entangled, and fig. 1 (b) is a schematic view showing a state in which fibers existing on the surface of a fiber sheet according to the prior art are arranged.

Fig. 2 is a schematic view showing one embodiment of the cleaning member of the present invention.

Fig. 3 (a) to (d) are schematic views showing another embodiment of the cleaning member of the present invention.

Fig. 4 is a schematic view showing a method for producing a single fiber using the production apparatus.

Fig. 5 (a) and (b) are an image and a graph showing the performance of removing fine particles when cleaning was performed using the cleaning members of the examples and comparative examples.

Detailed Description

Here, the cleaning cloth described in patent document 1 has a dense and high-density structure, and scrapes and removes fine particles such as abrasive grains and abrasive dust remaining on a surface to be cleaned.

However, the cleaning cloth described in this document is insufficient in removal of fine particles by scraping, and improvement in cleaning efficiency of fine particles is desired.

Accordingly, the present invention relates to a cleaning member having improved cleaning performance of fine particles adhering to a surface to be cleaned, and a method for manufacturing the same.

The present invention will be described below based on preferred embodiments thereof with reference to the accompanying drawings. The present invention relates to a cleaning member.

Cleaning in the present invention means both cleaning and wiping of objects, and includes, for example, cleaning of buildings such as floors, walls, ceilings, and columns, cleaning of buildings (doors, sliding doors, partition panels, and the like) or spare parts, wiping of various articles, and wiping of body and body-related equipment.

The cleaning member of the present invention is particularly suitable for cleaning the surface of a precision electronic component requiring smoothness on the surface to be cleaned, such as a semiconductor substrate such as a silicon wafer or a semiconductor wafer, or a substrate for a magnetic memory.

The cleaning member of the present invention has a nonwoven structure including an aggregate of single fibers. The nonwoven structure is conformed by the entanglement of the individual fibers with each other.

The nonwoven structure is a stack of randomly stacked single fibers, and the single fibers are entangled with each other, and if necessary, the stack is subjected to shape retention such as pressing. Between the single fibers, voids that do not exist in the single fibers are present three-dimensionally while penetrating in the plane direction and the thickness direction of the sheet, and the voids communicate with each other, forming fine voids (hereinafter, also referred to as fine pores) in the nonwoven structure. The voids are typically interconnected openings.

The single fibers contained in the nonwoven structure may have portions in contact with each other, but are not bonded to each other by welding or the like. When the single fibers have contact points with each other, the single fibers are not bonded to each other, but it is preferable that the cross-sectional shape of at least one of the single fibers at the contact points with each other is deformed into a shape different from the cross-sectional shape of the single fiber at the non-contact points. The term "single fiber" as used herein means a single fiber that does not form a fiber bundle, and is intended to exclude fibers formed by a fiber bundle.

The median fiber diameter of the single fibers is preferably 100nm or more, more preferably 200nm or more, further preferably 250nm or more, and preferably 2000nm or less, more preferably 1000nm or less, further preferably 900nm or less.

By using the single fiber having such a fiber diameter, it is possible to effectively remove fine particles having a particle diameter of 100nm or less adhering to the surface to be cleaned.

The fiber diameter of the fibers can be observed, for example, by a Scanning Electron Microscope (SEM) on the observation target surface of the nonwoven structure, and the fibers except for the lump of the fibers and the intersection of the fibers are arbitrarily selected 500 by dividing from the two-dimensional image thereof, and when the length between the intersection points of 2 points where the straight lines orthogonal to the longitudinal direction of the fibers intersect the fiber profile is taken as the fiber diameter, the median fiber diameter is taken as the median fiber diameter.

The nonwoven structure may contain fibers having a fiber diameter of less than 100nm or more than 2000nm, and preferably contains only single fibers of 100nm to 2000nm, as long as the effects of the present invention are not impaired.

The thickness of the nonwoven structure is preferably 0.02mm or more, more preferably 0.04mm or more, further preferably 0.06mm or more, and preferably 30mm or less, more preferably 25mm or less, and further preferably 20mm or less.

By having such a thickness, the strength of the cleaning member can be maintained, and the removal performance of the fine particles adhering to the cleaning object is excellent.

The nonwoven structure having a thickness in such a range may have a sheet shape, or a block shape such as a plate shape, a prism shape, a cylinder shape, or a block shape.

The thickness of the nonwoven structure can be appropriately adjusted by, for example, the content of single fibers or compression at the time of molding. The thickness of the nonwoven structure can be measured by observing the cross section of the nonwoven structure to be measured using a scanning electron microscope, for example, as described later.

The sheet shape in the present invention means a shape in which the thickness of the nonwoven structure is 10 μm or more and 1000 μm or less.

The bulk shape is a shape having a size that can be visually recognized, and for example, a shape having a thickness exceeding 1mmm when the length of the shortest dimension among three dimensions of the length, width, and depth of the nonwoven structure is taken as the thickness. The thickness here means the thickness of the nonwoven structure when no load is applied, as measured by the measurement method described later.

The nonwoven structure, regardless of any of the above shapes, preferably has an apparent density of 0.05g/cm ³Above, more preferably 0.10g/cm³Above, more preferably 0.20g/cm³Above, and preferably 0.60g/cm³Hereinafter, more preferably 0.55g/cm³The concentration is preferably 0.50g/cm or less³The following.

By setting the density to such a value, the fine particles adhering to the surface to be cleaned can be easily scraped off by the single fibers, and the number of voids between the single fibers increases, whereby the retention of the fine particles to be removed in the nonwoven structure can be improved, and as a result, the fine particles adhering to the object to be cleaned can be effectively removed.

The nonwoven structure having such an apparent density can be produced, for example, by a method described later.

The apparent density of the nonwoven structure can be measured by the following method. Specifically, the nonwoven structure was cut with a single-edge blade (product number FAS-10) manufactured by Feather safety razor company to form a cross section of the nonwoven structure. Then, the obtained cross section was observed under magnification using a scanning electron microscope (model JCM-5100) manufactured by japan electronics corporation. The cross section obtained by the enlarged observation was used as image data or a printed matter, and the thickness of the nonwoven structure was measured without load. The fluffed fibers inevitably present on the surface of the nonwoven structure are not the object of measurement. The thickness of the nonwoven structure is an average value of the thicknesses in the images obtained by the above-described enlarged observation. Then, the nonwoven structure is cut so as to have a predetermined area (for example, 4cm × 4cm), and the grammage is calculated from the mass and the area, and the grammage is divided by the thickness to calculate the apparent density.

According to the cleaning member having the above configuration, since the constituent fibers of the nonwoven structure including the single fibers are fine fibers and a plurality of openings communicating with fine voids are formed between the fibers, and the apparent density is low, the fine particles existing on the surface to be cleaned can be scraped off by the single fibers, and the fine particles adhering to the surface to be cleaned can be efficiently collected and removed. In addition, the fine particles can be retained in the gaps between the fibers, and the surface to be cleaned can be prevented from being re-contaminated. As a result, the fine particles on the surface to be cleaned have excellent cleaning performance. In addition, when the cleaning member of the present invention is used for cleaning an object to be cleaned such as a semiconductor substrate of a semiconductor wafer represented by a silicon wafer, fine particles having a particle diameter of 100nm or less such as abrasive grains and abrasive dust remaining on the surface to be cleaned can be effectively removed, and the frequency of occurrence of surface defects due to the remaining fine particles can be reduced.

In particular, when the cleaning member is used together with a cleaning liquid such as a polishing liquid, particles generated by polishing can be adsorbed to the cleaning member side along with the cleaning liquid, and thus the cleaning and removal of the particles becomes more excellent.

In order to further enhance the above-described effects, the porosity of the nonwoven structure constituting the cleaning member is preferably in a specific range. The porosity (%) is a value calculated from the following formula (1). In the case of a raw material including a plurality of types of filaments, a density calculated from the density and the content mass ratio of each raw material is used as the density of the raw material of the filaments.

Void ratio (%) < 100 × ((density of raw material of single fiber [ g/cm))³]) - (apparent density of non-woven structure [ g/cm)³]) /(Density of raw Material for Single fiber [ g/cm ]³])···(1)

The porosity of the nonwoven structure in the present invention is preferably 30% or more, more preferably 40% or more, further preferably 50% or more, and preferably 75% or less, more preferably 70% or less, further preferably 65% or less.

As shown in fig. 1 (a), in the cleaning member of the present invention, since a plurality of single fibers T2 are entangled in a nonwoven state in which they are randomly oriented, the distance between the fibers varies from short to long, and the size of the gaps W formed between the fibers is also random. As a result, when the pore distribution of the cleaning member of the present invention is measured as the pore volume distribution, a high peak is observed in a range of a small pore diameter.

Specifically, the nonwoven structure preferably has a peak in a pore volume distribution in a pore diameter range of 50 μm or less and does not have a peak in a pore diameter range exceeding 50 μm, in addition to the porosity in the above-described appropriate range. In the present invention, "no peak is present in the range of pore diameters exceeding 50 μm" means that, when the peak height of the highest peak in the range of pore diameters of 50 μm or less, that is, the peak is taken as a reference, a peak having a peak height greater than half the peak height is absent in the range of pore diameters exceeding 50 μm.

On the other hand, in the conventional fiber sheet, that is, the fiber sheet, woven fabric, and knitted fabric produced by using fiber bundles or forming fiber bundles, as shown in fig. 1 (b), fibers T1 constituting the sheet exist with a certain orientation. In this case, in the conventional fiber sheet shown in fig. 1 (b), there are two regions, a fiber dense region U in which the distance between fibers is relatively short and the gap is small, and a fiber spaced region V in which the distance between fibers is relatively long and the gap is large. In the case of measuring the void distribution of such a fiber sheet, two peaks are observed, a peak from a fiber dense region having a smaller void and a peak from a fiber spaced region having a larger void.

The pore volume distribution of the nonwoven structure can be measured by the following method, for example, according to the mercury intrusion method specified in JIS R1655.

Specifically, 0.02g to 0.1g of a measurement sample was cut from a measurement object, a measuring unit into which the measurement sample was put was set in a mercury porosimeter (AutoPore IV9500, Micromeritics corporation), the mercury injection pressure P was increased within a predetermined range, and the cumulative pore volume V1(mL/g) of the measurement sample at that time was measured. Then, the converted pore diameter D (. mu.m) obtained by conversion according to the following formula (2) is plotted on the horizontal axis, and the logarithmic differential pore volume (D (V1)/D (log)₁₀D) (ii) a mL/g) is plotted on the vertical axis, and the pore volume distribution is obtained. That is, the pore volume distribution was obtained by taking the calculated pore diameter D as the abscissa and taking the pore volume obtained by differentiating the cumulative pore volume V1 by the logarithmic value of the pore diameter D as the ordinate.

D＝4γcosθ/P···(2)

(gamma: surface tension of mercury, theta: contact angle, P: mercury injection pressure)

The above measurement was carried out in an environment of 22 ℃ and 65% Relative Humidity (RH). The surface tension gamma of mercury is 480dyn/cm, the contact angle theta is 140 DEG, and the mercury injection pressure P is in the range of 0psia (0MPa) to 60000psia (413.685 MPa). Based on the distribution curve of the converted pore diameters D obtained under the measurement conditions, the cumulative total value of the converted pore diameters D in the range of 0.0018 μm to 100 μm is defined as the cumulative pore volume V1(mL/g), and the median value of the pore diameters on the distribution curve is defined as the pore diameter D in the present invention ₀(μm). The nonwoven structure of the present invention preferably has a pore volume distribution in which the cumulative pore volume is differentiated by a logarithmic value of the pore diameter, the pore volume distribution having a peak in a pore diameter range of 50 μm or less and no peak in a pore diameter range exceeding 50 μm.

From the same viewpoint, the pore diameter D of the nonwoven structure₀The pore diameter is preferably 10nm or more, more preferably 50nm or more, and preferably 50 μm or less, and more preferably 30 μm or less.

From the same viewpoint, the cumulative pore volume V1 of the nonwoven structure is preferably 0.8mL/g or more, more preferably 1.0mL/g or more, and preferably 20mL/g or less, more preferably 10mL/g or less. The nonwoven structure having the above-described void distribution, pore diameter, and pore volume can be produced, for example, by the method described later.

The cleaning member of the present invention can be formed by changing the shape of the nonwoven structure contained therein according to the structure or use of the object to be cleaned, or by combining the nonwoven structure with another member.

Specifically, as shown in fig. 2, the cleaning member 1 may be in the form of a nonwoven structure 2 including a molded body obtained by compression molding a stacked body obtained by winding a single fiber. The cleaning member 1 shown in the figure is a block-shaped compression molded body, and includes a nonwoven structure 2 in a plate state having two main surfaces 2a and 2a facing each other, and the cleaning object can be cleaned directly or by impregnating the nonwoven structure with water, a cleaning liquid, or the like. That is, in the embodiment shown in the figure, the shape of the cleaning member 1 is substantially the same as the shape of the nonwoven structure 2. In the embodiment shown in the figure, the effect of the present invention can be exhibited even if the cleaning surface (surface facing the surface to be cleaned) of the cleaning member 1 is any surface, and from the viewpoint of achieving efficiency of cleaning, the cleaning surface is preferably a surface having a large contact area with the surface to be cleaned, that is, the main surface 2 a.

The cleaning member may have a support member such as a sponge, a cleaning pad, or a roller in addition to the nonwoven structure, and the support member and the nonwoven structure may be arranged so as to contact each other.

Specifically, as shown in fig. 3 (a), the sheet-like nonwoven structure 2 may be disposed so as to cover the entire surface of the plate-like support member 3. Alternatively, as shown in fig. 3 (b), the sheet-like or plate-like bulk nonwoven structure 2 may be in the form of a laminate disposed on at least one plate surface of the plate-like support member 3.

As shown in fig. 3 (c), the sheet-like nonwoven structure 2 may be provided with a first roller 2A for winding out the sheet-like nonwoven structure 2 and a second roller 2B for winding up the wound-out nonwoven structure 2, and the support member 3 may be disposed on the upper surface of the wound-out sheet-like nonwoven structure 2, that is, the sheet-like nonwoven structure 2 conveyed in one direction by the roller-roller method may be disposed on one surface of the support member 3.

Alternatively, as shown in fig. 3 (d), the sheet-like nonwoven structure 2 may be disposed on the circumferential surface of the roll-shaped support member 3. In the embodiments shown in fig. 3 (a) to (d), by using the surface on which the nonwoven structure 2 is arranged as the cleaning surface of the cleaning member 1, the removal performance of the fine particles present on the surface to be cleaned is excellent.

In particular, in the embodiments shown in fig. 3 (b) to (d), the existing support member can be easily changed and used so as to improve the efficiency of cleaning and removing fine particles, without depending on the shape or material of the support member, and therefore, this is advantageous. From the viewpoint of preventing defects such as undesired damage to the surface to be cleaned, the support member 3 preferably contains polyurethane, polyvinyl acetal, an elastomer resin, or the like.

When the nonwoven structure is formed into a sheet, the grammage of the nonwoven structure may be appropriately selected depending on the specific use of the nonwoven structure.

Next, matters that can be commonly applied to the above-described embodiments will be described. When the nonwoven structure in the cleaning member is formed into a sheet shape, the water droplet penetration time is preferably in a specific range. Specifically, the penetration time of water droplets into the sheet-like nonwoven structure is preferably 1 minute or less, more preferably 40 seconds or less, and still more preferably 20 seconds or less.

By exhibiting such water absorbency, the cleaning performance of the particles can be further improved. In particular, when the cleaning member is used together with the cleaning liquid, the retention of the cleaning liquid can be improved, and as a result, the removal efficiency of the fine particles becomes higher. The shorter the penetration time of the water droplets into the sheet-like nonwoven structure, the higher the hydrophilicity of the single fibers.

The hydrophilicity of the fibers means that the water or aqueous liquid between the fibers is highly retained.

The penetration time of water droplets into a sheet-like nonwoven structure can be measured, for example, by the following method. That is, two sets of stainless steel (SUS) plates each having a plate thickness of 10mm were used, and both ends of a sheet-like nonwoven structure were sandwiched, and tension was applied to the nonwoven structure in this state, and the nonwoven structure was fixed with a space from a laboratory bench. Subsequently, 15. mu.L of ion-exchanged water as water droplets was dropped from above the nonwoven structure fixed in a state of being applied with tension. When the surface on which the water droplet was dropped was visually observed, the time from the time when the water droplet was dropped until the water droplet became completely indistinguishable was taken as the penetration time of the water droplet. The nonwoven structure was measured to have dimensions of 80mm × 50mm, and the distance between the SUS plate groups was 50mm, and the sample was sandwiched by applying tension to such an extent that the sample did not sag, and water droplets were dropped from a position 10mm higher than the center.

The method for producing the filaments constituting the nonwoven structure is not particularly limited as long as the thickness thereof is within the above range, and fibers produced by a melt blowing method or an electrospinning method can be used. The single fiber used in the present invention is particularly preferably a fiber obtained by electrospinning.

By using such fibers, a nonwoven structure containing small-diameter fibers and having a predetermined density can be easily produced. Electrospinning is a method in which a solution or a melt containing a resin as a raw material of a fiber is discharged into an electric field in a state where a high voltage is applied, and the discharged solution or melt is elongated and stretched, whereby a fiber having a long fiber length and a small fiber diameter can be formed.

The single fiber is preferably formed from a thermoplastic resin having fiber formability. Examples of such thermoplastic resins include: polyolefin resins such as polyethylene, polypropylene, ethylene- α -olefin copolymers and ethylene-propylene copolymers, polyester resins such as polyethylene terephthalate, polyamide resins such as polyamide 6 and polyamide 66, vinyl resins such as polyvinyl chloride and polystyrene, acrylic resins such as polyacrylic acid and polymethyl methacrylate, and the like, and these may be used alone or in combination of two or more.

The content of the thermoplastic resin used as the raw material resin is preferably 70 parts by mass or more, more preferably 75 parts by mass or more, and even more preferably 80 parts by mass or more, and preferably 98 parts by mass or less, more preferably 97 parts by mass or less, and even more preferably 90 parts by mass or less, relative to 100 parts by mass of all the constituent components of the single fibers.

When a solution of the resin is subjected to electrospinning, examples of the dispersing solvent for dispersing the resin include: aprotic polar solvents such as dimethyl sulfoxide, dimethylacetamide, dimethylformamide and N-methylpyrrolidone, alcohols such as glycerol, ethylene glycol and ethanol, ketones such as acetone and methyl ethyl ketone, halogen solvents such as dichloromethane and chloroform, and inorganic salt solvents such as aqueous solutions of nitric acid, zinc chloride and sodium thiocyanate, which may be used alone or in combination of two or more kinds of solvents.

The single fibers constituting the nonwoven structure preferably contain an ionic surfactant. By incorporating the single fibers with the ionic surfactant, a nonwoven structure containing fine fibers and having a predetermined density can be easily produced.

In addition, in the case of forming single fibers by electrospinning, since the charge amount of the raw material resin can be increased, the drawing of the solution or melt containing the resin can be efficiently performed, and as a result, fibers having a smaller diameter can be produced with higher production efficiency. Furthermore, the hydrophilicity of the produced fiber can be easily expressed.

The content of the ionic surfactant is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, further preferably 5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 6 parts by mass or less, with respect to 100 parts by mass of all the constituent components of the single fibers.

Examples of the ionic surfactant include cationic surfactants, zwitterionic surfactants, and anionic surfactants. One of these ionic surfactants may be used alone. Further, if these ionic surfactants are surfactants having the same ionic property, two or more kinds thereof may be used in combination. For example, as the ionic surfactant, various cationic surfactants, various zwitterionic surfactants, and various anionic surfactants may be used.

Examples of the cationic surfactant include: and amine salt type cationic surfactants such as fatty acid ester amine salts, fatty amide amine salts, urea condensed amine salts, and imidazoline salts, and quaternary ammonium salt type cationic surfactants such as tetraalkylammonium salts, trialkylbenzylammonium salts, quaternary ammonium organic acid salts, fatty acid amide type quaternary ammonium salts, and alkylpyridinium salts.

Examples of the zwitterionic surfactant include: amino acid type zwitterionic surfactants such as alkylglutamic acid, alkyl-beta-alanine, or salts thereof, and betaine type zwitterionic surfactants such as alkylbetaine.

Examples of the anionic surfactant include: salts of saturated or unsaturated fatty acids having 8 to 22 carbon atoms such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and erucic acid with metals such as Li, Na, Mg, K, Ca, Ba, and Zn, carboxylates such as polyoxyethylene alkyl ether carboxylate and alkyl hydroxy ether carboxylate, and salts of higher alcohol sulfuric acid esters (R-O-SO)₃M) and the like, polyoxyethylene alkyl ether sulfate (R-O- (CH)₂CH₂O)_n-SO₃M) alkyl ether sulfates, alkylsulfonates (R-SO)₃M), alkylbenzenesulfonate (R-Ph-SO)₃M), alkyl naphthalene sulfonate (R-Np-SO)₃M), olefin sulfonate (R-CH ═ CH- (CH)₂)_n-SO₃M and R-CH (-OH) (CH)₂)_n-SO₃M), alkyl sulfosuccinates (R-OOC-CH)₂-CH(-SO₃M) -COOM), dialkyl sulfosuccinates (R-OOC-CH)₂-CH(-SO₃M) -COO-R), alpha-sulfo fatty acid ester (R-CH (-SO)₃M)-COO-CH₃) Acyl isethionates (R-CO-O- (CH) ₂CH₂)-SO₃M), acyl taurates (R-CO-NH- (CH)₂)₂-SO₃M), acyl alkyl taurates (R-CO-N (-R') - (CH)₂)₂-SO₃M) N-alkyl-N-acylaminoalkylsulfonic acid, beta-naphthalenesulfonic acid formaldehyde condensate (M-O)₃S-Np-(CH₂-Np(-SO₃M))_n-H) and the like. These may be used alone, or two or more kinds may be used in combination.

In the above-mentioned sulfate ester salt and sulfonate, R represents a linear or branched alkyl group, and the number of carbon atoms thereof is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, and preferably 22 or less, more preferably 20 or less, further preferably 18 or less.

R' represents a linear or branched alkyl group, and the number of carbon atoms is preferably 5 or less.

Ph represents a phenyl group which may be substituted.

Np represents a naphthyl group which may be substituted. M represents a monovalent cation, preferably a metal ion, and more preferably a sodium ion.

n represents a number of preferably 6 or more, more preferably 8 or more, and even more preferably 10 or more, and preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less.

These sulfate ester salts and sulfonates may be used alone or in combination of two or more.

When the single fibers contain an ionic surfactant, among the ionic surfactants, an anionic surfactant is preferably used, and sulfonate is more preferred. By containing such a surfactant, it is possible to efficiently produce a nonwoven structure having a small-diameter single fiber and a predetermined density.

The cleaning member of the present invention may contain other components than the raw materials constituting the single fibers in the nonwoven structure as long as the effects of the present invention can be exerted. Examples of such other components include polyurethane, polyvinyl acetate, cellulose, and derivatives thereof.

The other constituent components may be contained in a fibrous form constituting the nonwoven structure, or may be contained in a layered form such as being laminated on one surface of the nonwoven structure.

In this case, the smaller the content of the other constituent components, the better, and the more preferably 0.5 parts by mass or more, further preferably 1 part by mass or more, and preferably 95 parts by mass or less, further preferably 90 parts by mass or less, relative to 100 parts by mass of all the constituent components of the single fiber.

In the cleaning member of the present invention, additives may be blended with the single fibers as long as the effects of the present invention are not impaired.

Examples of the additives include antioxidants, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and metal deactivators.

Examples of the antioxidant include a phenol-based antioxidant, a phosphite-based antioxidant, and a sulfur-based antioxidant.

Examples of the light stabilizer and the ultraviolet absorber include hindered amines, nickel complexes, benzotriazoles, and benzophenones. Examples of the lubricant include higher fatty acid amides such as stearic acid amide.

Examples of the antistatic agent include fatty acid partial esters such as fatty acid monoglycerides. Examples of the metal inactivator include phosphines, epoxies, triazoles, hydrazides, and oxamides.

When the single fibers further contain an additive, the content of the additive is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of all the components of the single fibers.

The nonwoven structure constituting the cleaning member is preferably impregnated with a cleaning liquid for the purpose of cleaning, from the viewpoint of improving the efficiency of cleaning the fine particles of the cleaning object.

The cleaning liquid may be water alone or a dispersion liquid containing, in addition to water, a surfactant, a bactericide, a perfume, an aromatic agent, a deodorant, a pH adjuster, an organic solvent such as alcohol, and a cleaning agent such as abrasive grains.

In addition, a chemical liquid or a polishing liquid, which is generally used for polishing electronic components such as substrates, may be impregnated as the cleaning liquid.

The above description relates to a cleaning member, and a method for manufacturing the cleaning member is described below.

The method is roughly divided into two steps, namely, a spinning step of ejecting a solution or a melt of an electrospinning composition containing a raw material of single fibers into an electric field, and spinning the solution or the melt by an electrospinning method to form a deposit of single fibers; and a pressing step of pressing the stacked body to form a nonwoven structure having a predetermined density.

In the following description, an electrospinning method using a melt containing a resin, which is a preferred embodiment of the production method of the present invention, will be described as an example.

When electrospinning is performed using a melt of the electrospinning composition, the electrospinning can be suitably performed by a manufacturing apparatus 10 shown in fig. 4, for example.

The manufacturing apparatus 10 shown in fig. 4 is roughly divided into a composition supply section 10A, an electrode section 10B, a fluid ejection section 10C, and a trap section 10D.

The manufacturing apparatus 10 includes a composition supply section 10A having a housing 11, a nozzle 12, and a hopper 19 for supplying the composition 1P for electrospinning. In the housing 11, the electrospinning composition 1P supplied from the hopper 19 can be heated and melted in the housing 11 to prepare a melt R of the electrospinning composition. The melt R can be supplied to a nozzle 12 described later by a screw (not shown) provided in the housing 11.

The nozzle 12 is a member for ejecting the melt R into an electric field, and includes a nozzle base 13 and a nozzle tip 14. The nozzle 12 is made of a conductive material such as metal. The nozzle base 13 and the nozzle tip 14 are electrically insulated from each other by an insulating member (not shown). The casing 11, the nozzle 12, and the nozzle base 13 are communicated with each other, so that the melt R in the casing 11 can be ejected from the ejection port of the nozzle tip portion 14. The nozzle tip 14 is grounded, and therefore grounded.

The nozzle tip 14 is heated by heat transfer from a heater (not shown) provided in the nozzle base 13 or heat transfer from the melt R in the casing 11, for example.

The heating temperature of the melt R in the nozzle tip portion 14 also depends on the constituent components of the electrospinning composition, and is preferably 100 ℃ or higher, more preferably 200 ℃ or higher, and preferably 450 ℃ or lower, and more preferably 400 ℃ or lower.

The manufacturing apparatus 10 includes an electrode portion 10B having a charged electrode 21 and a high voltage generating device 22 connected thereto. The charging electrode 21 is disposed at a predetermined distance from the nozzle tip 14, and is spaced apart from the nozzle tip 14.

With this configuration, an electric field is generated between the tip end portion 14 of the nozzle 12 and the charging electrode 21 to which a high voltage is applied by the high voltage generator 22, and the melt R discharged from the nozzle tip end portion 14 can be charged.

The charging electrode 21 is preferably made of a conductive material such as metal or covered with a dielectric material.

The distance between the nozzle 12 and the charging electrode 21 is preferably 10mm or more, and preferably 150mm or less, depending on the desired fiber diameter (diameter) of the fibers or the collectability on a collecting electrode 27 described later. If the distance between the nozzle 12 and the charging electrode 21 is within this range, a spark or corona discharge is less likely to occur between the nozzle 12 and the charging electrode 21, and a malfunction of the manufacturing apparatus 10 is less likely to occur.

The manufacturing apparatus 10 further includes a fluid ejection portion 10C. The fluid ejecting section 10C includes a fluid ejecting device 23 below an imaginary straight line connecting the composition supply section 10A and the electrode section 10B.

The fluid ejecting apparatus 23 is provided between the composition supply portion 10A and the electrode portion 10B.

Between the tip of the nozzle tip 14 and the charging electrode 21, the air flow a flows in a direction intersecting the direction connecting the two. The air flow a is ejected from the fluid ejection device 23.

The melt R discharged from the nozzle tip 14 is conveyed by the air flow a, and thus fibers having a further extremely fine size can be formed. For this purpose, air as the heating fluid is preferably used as the air flow a.

The temperature of the heated air also depends on the constituent components of the electrospinning composition, and is preferably 100 ℃ or higher, more preferably 200 ℃ or higher, and preferably 500 ℃ or lower, and more preferably 400 ℃ or lower.

For the same purpose, the flow rate of the air flow a at the discharge port of the fluid ejecting device 23 when discharging the air flow a is preferably 50L/min or more, more preferably 150L/min or more, and preferably 500L/min or less, more preferably 400L/min or less.

The manufacturing apparatus 10 further includes a trap portion 10D.

The collecting section 10D includes a collecting sheet 24 for collecting the fibers F, a conveyor 25 for conveying the fibers F, a high voltage generator 26, and a collecting electrode 27.

The trap portion 10D is provided at a position above a virtual line connecting the composition supply portion 10A and the electrode portion 10B and facing the fluid ejection portion 10C. The collecting section 10D is electrically connected to each other.

The capture sheet 24 is taken out from the blank roll 24a and conveyed to a conveyor 25.

A collecting electrode 27 for collecting the fibers obtained by electrospinning is disposed inside the conveyor 25. The collecting electrode 27 is connected to a high voltage generator 26, and a high voltage is applied to the collecting electrode 27 by the high voltage generator 26.

By applying a high voltage to the collecting electrode 27, the fibers F are pulled to the negatively charged conveyor 25 side and accumulated on the surface of the collecting sheet 24. Instead of being connected to the high voltage generator 26, the collecting electrode 27 may be grounded to the ground.

The above is an explanation of the manufacturing apparatus 10 shown in fig. 4, and a method for manufacturing a fiber of the present invention using the manufacturing apparatus 10 will be explained below.

First, the hopper 19 is filled with the electrospinning composition 1P, and the electrospinning composition is heated and melted in the housing 11. The melt R is extruded to the nozzle 12, and the melt R is supplied to the discharge port of the nozzle tip 14.

The composition 1P for electrospinning contains a thermoplastic resin as a raw material resin of the target filaments, and if necessary, an ionic surfactant and an additive, and a composition obtained by mixing these components can be used.

The method for producing the composition 1P for electrospinning is not particularly limited, and for example, the composition may be produced by mixing the above-mentioned raw materials in advance to produce a master batch, or alternatively, the raw materials may be individually supplied to the production apparatus 10, and heated, melted, and kneaded in the apparatus.

Next, the melt R is discharged from the nozzle tip 14 into an electric field, and spun by an electrospinning method (spinning step). In order to generate the electric field, for example, the electric field can be generated by grounding the tip portion 14 of the nozzle 12, connecting the charging electrode 21 to the high voltage generator 22, and applying a voltage. The charged melt R is repeatedly stretched by an attractive force and a self-repulsive force obtained by the charge of the melt R itself, and is attracted to the charged electrode 21 by the electrical attractive force while being very slender.

From the viewpoint of satisfying both the efficiency of drawing the melt R and the efficiency of producing fibers, the discharge amount of the molten electrospinning composition is preferably 1g/min or more, more preferably 2g/min or more, and preferably 20g/min or less, and more preferably 5g/min or less.

From the viewpoint of facilitating drawing of the melt R during electrospinning and making the diameter of the produced fiber smaller, the Melt Flow Rate (MFR) of the molten electrospinning composition is preferably 10g/min or more, and particularly preferably 100g/min or more, at the discharge port of the nozzle tip portion 14.

Melt Flow Rate (MFR) according to JIS K7210 in the case of using, for example, a polypropylene resin as a raw material resin, it was measured at 230 ℃ under a load of 2.16kg using a die having a hole diameter of 2.095mm and a length of 8 mm.

Thereafter, by further blowing an air flow a from the fluid jet device 23 to the melt R, the melt R ejected from the nozzle tip portion 14 is further stretched and the extremely fine fibers are transported while being produced. The melt R discharged from the nozzle tip 14 is transported by the air flow a before reaching the charging electrode 21, and the flight direction thereof is changed, and the melt R is stretched to be extremely fine and solidified, thereby producing the fiber F. The fibers F generated from the melt R are transported by the air flow a, and are attracted by the electric attraction force generated by the collecting electrode 27, and are deposited on the surface of the collecting sheet 24 facing the fluid ejecting apparatus 23.

The voltage applied between the nozzle 12 and the charging electrode 21 or the collecting electrode 27 is preferably-100 kV or more, more preferably-80 kV or more, and preferably-5 kV or less, more preferably-10 kV or less.

When the applied voltage is within this range, the melt R is easily charged well, and the production efficiency of the fiber having a small fiber diameter can be further improved. Further, a spark or corona discharge is less likely to occur between the nozzle 12 and the charging electrode 21 or the collecting electrode 27, and a malfunction of the apparatus is less likely to occur.

The fibers thus produced are considered to be 1 continuous fiber, i.e., a single fiber, between the nozzle 12 and the collecting sheet 24. Even if the fibers are temporarily cut depending on the production conditions, the surrounding environment, or the like, the cut fibers immediately contact each other, and as a result, the ultrafine fibers can be considered as 1 fiber continuous between the nozzle 12 and the collecting sheet 24. The single fibers are accumulated in the collection sheet 24, and a single fiber accumulation body is formed on the collection sheet 24.

The single fibers and the accumulated bodies thereof produced through the above steps are obtained by spinning the above-mentioned composition for electrospinning as a raw material, and the composition obtained by melt electrospinning does not substantially change in quality, so that the composition for electrospinning as a raw material has substantially the same composition as that of the single fibers as a product.

In the case of electrospinning using a solution of the electrospinning composition, for example, fibers can be spun using the production apparatus described in japanese patent laid-open nos. 2012 and 012715 and 2015 and 52193 instead of the production apparatus 10 described above.

Specifically, the apparatus includes a nozzle for discharging a solution of the composition for electrostatic spinning, an injector communicating with the nozzle and capable of supplying the composition for electrostatic spinning to the nozzle, and a conductive collector (not shown) for collecting fibers spun, and is capable of spinning while applying a voltage between the injector and the conductive collector. The solution of the composition is contained in a syringe, the solution is supplied from the syringe to a nozzle, the solution is discharged from the nozzle into an electric field, and ultrafine filaments including a raw material resin are spun by an electrospinning method, whereby a deposition body of the filaments can be formed on the conductive collector.

The electrospinning method can be carried out under appropriately changed conditions in order to produce a single fiber having a desired fiber diameter and fiber length. In particular, a single fiber called a nanofiber having an extremely small fiber diameter can be produced.

The median fiber diameter of the single fibers is preferably 100nm or more and 2000nm or less, as described above.

The average fiber length of the single fibers is preferably 10mm or more, more preferably 50mm or more, and still more preferably 100mm or more. The average fiber length of the single fibers can be measured as the length of 500 fibers in the longitudinal direction, and is set as the arithmetic average value thereof.

Next, the resulting single-fiber stack is pressed to form a stack having an apparent density of preferably 0.05g/cm³Above and 0.60g/cm³The following nonwoven structure. In order to set the apparent density of the nonwoven structure in such a range, the pressure and temperature to be applied may be controlled. The pressure applied can be appropriately changed so that the nonwoven structure has a desired shape.

As shown in fig. 2, when a stack of single fibers is molded to be a compression molded body, for example, the resulting stack of single fibers is put in a mold corresponding to the size and shape of a target nonwoven structure and pressurized, whereby a compression molded nonwoven structure 2 can be produced.

In this case, the pressure applied to the stack is preferably 10N/cm²Above, more preferably 100N/cm²Above, and preferably 100000N/cm ²Hereinafter, it is more preferably 50000N/cm²The following.

The temperature at the time of pressing can be set as appropriate at a temperature not exceeding the melting point or the flow point of the raw material resin of the monofilament. In the case of using a plurality of resins as the raw material resin, the temperature is set based on the resin having the lowest melting point or flow point among the resins used.

Regarding the flow point, the resin to be measured was made into a plate-like solid having a length of 40mm × a width of 5mm × a thickness of 1mm, and was supplied to a viscoelasticity measuring apparatus (for example, DMA7100 manufactured by hitachi high and new technologies). When the dynamic viscoelasticity is measured while raising the temperature in a temperature range higher than the glass transition temperature and the glass transition region of the resin to be measured (the frequency at the time of measurement is set to 1Hz, and the strain amplitude is set to 0.025%), the state where the storage elastic modulus E 'is higher than the loss elastic modulus E "is changed to a state where the loss elastic modulus E" is higher than the storage elastic modulus E', and the flow point is the temperature at the intersection of the storage elastic modulus-temperature curve and the loss elastic modulus-temperature curve at that time.

As shown in fig. 3 (a) to (d), when the nonwoven structure 2 is formed by molding a stack of single fibers into a sheet or a plate, for example, the resulting stack of single fibers is introduced between a pair of press rolls, whereby a sheet or a plate-like nonwoven structure can be formed.

The pressure and temperature at the time of pressing may be the above-described pressure and temperature.

By pressing the nonwoven structure under the above-described conditions, the filaments are not fused to each other, and the cross-sectional shape of at least one of the filaments at the contact point between the filaments is deformed into a shape different from the cross-sectional shape of the filaments at the non-contact point, regardless of the form of the nonwoven structure.

As shown in fig. 3 (a) to (d), when the support member 3 is provided in addition to the nonwoven structure 2, the cleaning member 1 having the nonwoven structure 2 and the support member 3 can be produced by further performing steps such as a step of covering the outer surface of the support member with the sheet-like nonwoven structure 2, a step of laminating the sheet-like or plate-like nonwoven structure and the support member, or a step of winding the sheet-like nonwoven structure 2 around the outer surface of the support member.

The method of joining the nonwoven structure 2 and the support member 3 is not particularly limited as long as the effects of the present invention can be exerted, and for example, joining means such as heat sealing and an adhesive may be used to join the nonwoven structure and the support member partially or entirely.

In the case where the ionic surfactant is contained in the composition for electrospinning, it is also preferable to heat-treat at least the nonwoven structure from the viewpoint of more effectively expressing hydrophilicity on the fiber surface and improving hydrophilicity of the nonwoven structure.

The method of heat treatment is not particularly limited under the condition that fusion of the single fibers does not occur, and examples thereof include a method of treating the fibers by blowing hot air, a method of irradiating the fibers with infrared rays, a method of immersing the fibers in a heated liquid such as hot water, a method of passing the fibers between a pair of heated rollers, a method of holding the fibers in a heated space such as a thermostatic bath, and a method of pressing the fibers by sandwiching the fibers between heated metal plates.

These methods may be performed directly on the spun single fibers or a stacked body thereof, simultaneously with molding the single fibers into a predetermined shape to produce a molded article of fibers, or may be performed after forming the molded article.

As a condition under which the fusion of the single fibers does not occur, for example, as described above, the heat treatment may be performed at a temperature not exceeding the melting point or the flow point of the raw material resin of the single fibers.

The cleaning member having the nonwoven structure thus manufactured can be used as a cleaning member alone, or mounted on a cleaning tool such as a squeegee or a cleaning device, and used for cleaning the surface of a cleaning object such as a building such as a floor surface or a wall surface, a building such as a cabinet, a window glass, a mirror, a door handle, or the like, furniture such as a carpet, a dining table, or the like, or the skin surface of a body.

The cleaning member may be used in a dry state or in a state impregnated with a cleaning liquid or chemical solution.

In particular, the cleaning member of the present invention can effectively clean and remove fine particles having a particle diameter of about several tens to several hundreds nm such as abrasive grains, and thus can be suitably used for cleaning the surface of a precision electronic component whose surface to be cleaned is highly required to have smoothness, such as a semiconductor substrate such as a silicon wafer or a magnetic storage substrate, and can reduce the frequency of surface defects of these substrates.

The present invention has been described above based on preferred embodiments thereof, but the present invention is not limited to the above embodiments. For example, the manufacturing apparatus 10 shown in fig. 4 is provided with the composition supply unit 10A and the fluid ejecting unit 10C separately, but instead, the fluid ejecting unit 10C may be incorporated in the composition supply unit 10A.

Specifically, as shown in japanese patent application laid-open No. 2016-204816, a production apparatus may be provided which comprises a nozzle for discharging a solution or a melt of an electrospinning composition, an electrode for generating an electric field between the nozzle and the nozzle, a high voltage generating device for applying a voltage to the electrode, and a collecting portion for collecting fibers produced from the electrospinning composition, wherein a flow passage through which the solution or the melt can flow is formed between a casing and the nozzle, and a fluid ejecting portion is formed so as to surround the flow passage.

In this case, instead of the electrode portion 10B, a voltage may be applied to the collecting electrode 27 of the collecting portion 10D to generate an electric field between the collecting electrode and the nozzle, and in this state, the solution or the melt may be directly discharged from the nozzle 12 to the collecting portion 10D.

The fluid ejection portion 10C of the present embodiment can eject the air flow a in the ejection direction of the melt R in the nozzle 12.

In the manufacturing apparatus 10 shown in fig. 4, the electrode for generating an electric field between the charging electrode 21 and the nozzle 12 is provided separately from the composition supply unit 10A, and instead, the charging electrode 21 may be incorporated in the composition supply unit 10A.

Specifically, as shown in japanese patent application laid-open No. 2016-.

In this case, the collecting section 10D disposed to face the nozzle 12 may be provided with a suction means such as a suction box which is not electrically connected, for example, instead of the collecting electrode 27, and may collect the spun fibers F and deposit the fibers on the collecting sheet 24.

The present invention further discloses the following cleaning member and a method for manufacturing the same in relation to the above-described embodiment.

＜1＞

A cleaning member having a nonwoven structure which is formed by winding single fibers having a median fiber diameter of 100nm to 2000nm and is in a shape retaining state,

the apparent density of the nonwoven structure was 0.05g/cm³Above and 0.60g/cm³The following.

＜2＞

The cleaning member according to the above < 1 >, wherein the nonwoven structure has a void ratio of 30% or more and 75% or less,

the pore volume distribution obtained by differentiating the cumulative pore volume by the logarithmic value of the pore diameter has a distribution having a peak in the pore diameter range of 50 μm or less and no peak in the pore diameter range exceeding 50 μm.

＜3＞

The cleaning member according to the above < 1 > or < 2 >, wherein the nonwoven structure is a compression-molded product of a stacked body in which the single fibers are wound.

＜4＞

The cleaning member as described in any of the above < 1 > to < 3 >, further comprising a support member,

the support member and the nonwoven structure are disposed in contact with each other.

＜5＞

The cleaning member according to the above < 4 >, wherein the nonwoven structure is disposed so as to cover the entire surface of the support member.

＜6＞

The cleaning member according to < 4 > above, wherein the nonwoven structure in a sheet or block form is disposed on at least one surface of the plate-like support member.

＜7＞

The cleaning member according to the above < 4 >, wherein the sheet-like nonwoven structure is disposed on the circumferential surface of the roller-shaped support member.

＜8＞

The cleaning member as described in any one of the above items < 1 > to < 7 >, wherein the nonwoven structure is in a sheet form, and a water droplet penetration time into the nonwoven structure is within 1 minute.

＜9＞

The cleaning member according to any one of the above items < 1 > to < 8 >, wherein the nonwoven structure is in a sheet form, and the penetration time of water droplets into the nonwoven structure is preferably 1 minute or less, more preferably 40 seconds or less, and still more preferably 20 seconds or less.

＜10＞

The cleaning member as described in any of the above items < 1 > to < 9 >, wherein the single fibers are fibers obtained by electrospinning.

＜11＞

The cleaning member as described in any of the above < 1 > to < 10 >, wherein the single fibers comprise a thermoplastic resin,

the thermoplastic resin is selected from polyolefin resins such as polyethylene, polypropylene, ethylene-alpha-olefin copolymer, ethylene-propylene copolymer, etc.; polyester resins such as polyethylene terephthalate; polyamide resins such as polyamide 6 and polyamide 66; vinyl resins such as polyvinyl chloride and polystyrene; and at least one of acrylic resins such as polyacrylic acid and polymethyl methacrylate.

＜12＞

The cleaning member according to < 11 > above, wherein the content of the thermoplastic resin is preferably 70 parts by mass or more, more preferably 75 parts by mass or more, further preferably 80 parts by mass or more, and preferably 98 parts by mass or less, more preferably 97 parts by mass or less, further preferably 90 parts by mass or less, based on 100 parts by mass of all the components of the single fibers.

＜13＞

The cleansing member according to any one of the above < 1 > to < 12 >, wherein the single fibers contain an ionic surfactant.

＜14＞

The cleaning member according to < 13 > above, wherein the content of the ionic surfactant is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, further preferably 5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 6 parts by mass or less, based on 100 parts by mass of all the components of the single fibers.

＜15＞

The cleaning member as described in any of the above items < 1 > to < 14 >, wherein the apparent density of the nonwoven structure is preferably 0.05g/cm³Above, more preferably 0.10g/cm³Above, more preferably 0.20g/cm³Above, and preferably 0.60g/cm ³Hereinafter, more preferably 0.55g/cm³The concentration is preferably 0.50g/cm or less³The following.

＜16＞

The cleaning member according to any one of the above items < 1 > to < 15 >, wherein the nonwoven structure has a void ratio of preferably 30% or more, more preferably 40% or more, still more preferably 50% or more, and preferably 75% or less, more preferably 70% or less, and still more preferably 65% or less.

＜17＞

The cleaning member according to any one of the above items < 1 > to < 16 >, wherein the nonwoven structure has a cumulative pore volume of preferably 0.8mL/g or more, more preferably 1.0mL/g or more, and preferably 20mL/g or less, more preferably 10mL/g or less.

＜18＞

A method for producing a cleaning member described in any one of the above-mentioned < 1 > to < 17 >, comprising:

a step of ejecting a solution or a melt of the composition for electrospinning into an electric field, and spinning the composition by an electrospinning method to form a deposit of single fibers; and

the stacked body was pressed to have an apparent density of 0.05g/cm³Above and 0.60g/cm³The following steps of the nonwoven structure.

＜19＞

The method of producing a cleaning member as described in < 18 > above, wherein the deposit is applied preferably at 10N/cm ²Above, more preferably 100N/cm²Above, and preferably 100000N/cm²The concentration is preferably 50000N/cm²The nonwoven structure as a compression-molded body was formed under the following pressure.

＜20＞

The method of manufacturing a cleaning member as described in < 18 > above, wherein the stacked body is introduced between a pair of press rolls to form a sheet-like or plate-like nonwoven structure.

＜21＞

A method for producing a cleaning member as described in any of the above < 18 > to < 20 >, comprising: the cleaning member having the nonwoven structure and the support member is formed by any one of a step of covering the outer surface of the support member with the nonwoven structure in a sheet form, a step of laminating the nonwoven structure in a sheet form or a plate form with the support member, and a step of winding the nonwoven structure in a sheet form around the outer surface of the support member.

＜22＞

The method for manufacturing a cleaning member according to any one of the above items < 18 > to < 21 >, wherein the nonwoven structure is subjected to a heat treatment.

＜23＞

The method for producing a cleaning member as described in any of the above < 18 > to < 22 >, wherein the resin-containing electrostatic spinning composition is used to form a deposit of single fibers containing the resin by electrostatic spinning,

The stacked body was pressed to obtain an apparent density of 0.05g/cm³Above and 0.60g/cm³The following non-woven structure is described,

the nonwoven structure is subjected to a heat treatment at a temperature not exceeding the melting point or the flow point of the resin.

Examples

The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to this embodiment.

[ example 1]

Using the production apparatus 10 shown in FIG. 4, a polypropylene resin (PP; MF650Y, melting point 160 ℃ C., manufactured by PolyMirae) as a raw material resin and sodium alkylsulfonate (Mersolat H-95, manufactured by Bayer AG) as an ionic surfactant were supplied into the casing 11 in a proportion containing 5 parts by mass of the ionic surfactant per 100 parts by mass of the total of the raw material resin and the ionic surfactant, and the mixture was heated, melted and kneaded in the casing 11 to produce a molten electrospinning composition. Further, a deposit of single fibers was produced by a melt electrospinning method using the composition for electrospinning in a molten state under the following production conditions. The resulting filaments had a median fiber diameter of 900 nm.

[ conditions for producing Single fibers ]

Manufacturing environment: 27 ℃ and 50% RH

Heating temperature in the housing 11: 220 deg.C

Discharge amount of the melt R: 1g/min

Voltage applied to the nozzle tip 14 (made of stainless steel): 0kV (ground earth)

Applied voltage to charged electrode 21(80 mm. times.80 mm, thickness 10mm, stainless steel): -40kV

Distance between the nozzle tip 14 and the trap portion 10D: 600mm

Temperature of air flow ejected from the fluid ejection device 23: 350 deg.C

Flow rate of the air flow ejected from the fluid ejection device 23: 320L/min

Next, the obtained single-fiber stack was supplied to a hand press (Mini test press-10, manufactured by Toyo Seiki Seisaku-Sho Co., Ltd.) and was set at 9400N/cm at room temperature (25 ℃ C.)²The nonwoven structure is pressed to produce a sheet-like nonwoven structure which is formed by winding single fibers and is shaped into a shape. The thickness of the nonwoven structure was 76 μm, and the water droplet penetration time was 45 seconds. The apparent density of the nonwoven structure was 0.4g/cm³The porosity was 55%, and the pore distribution exhibited a peak at a position having a pore diameter of 8 μm. The nonwoven structure was arranged so as to cover the entire outer surface of a plate-like supporting member (substrate cleaning pad made of polyvinyl acetal, model number: W series, manufactured by AION corporation), to obtain a cleaning member 1 of the present example.

Comparative example 1

The plate-like support member described above was used as a cleaning member as it is. That is, the cleaning member of the present comparative example was constituted only by the plate-like support member, and the nonwoven structure was not arranged.

[ example 2]

A cleaning member comprising a nonwoven structure as a compression-molded article was produced. More specifically, the single-fiber stack (grammage: 10 g/m) obtained by the above-described method was placed so as to fill a rectangular parallelepiped mold having a length of 18mm, a width of 18mm and a depth of 30mm²) Next, the single-fiber stack was applied to a mold of 18mm square at room temperature (25 ℃ C.) at 25N/cm²The nonwoven structure is compressed and molded into a rectangular parallelepiped shape. The nonwoven structure had an apparent density of 0.2g/cm³。

[ evaluation of cleaning Properties of microparticles ]

The cleaning members of example 1 and comparative example 1 were mounted on a substrate cleaning apparatus, and the number of surface defects of the silicon wafer was measured, thereby evaluating the cleaning performance of the fine particles. The specific procedure was performed in the order of finish polishing of the silicon wafer, cleaning with a cleaning member, and measurement of surface defects. Details and conditions of the evaluation order are shown below.

< 1. Fine grinding >

The silicon wafer was polished under the following polishing conditions using a polishing slurry having the following composition and the silicon wafer. The silicon wafer was roughly polished using a commercially available polishing liquid, and then subjected to finish polishing under the following finish polishing conditions. The haze of the roughly ground silicon wafer is 2 to 3 ppm. Haze is the value of dark field wide angle oblique incidence channel (DWO) measured using a "Surfscan SP 1-DLS" device manufactured by KLA Tencor.

(Fine polishing solution)

A polishing concentrate obtained by mixing hydroxyethylcellulose (manufactured by Daicel K.K., SE-400, molecular weight 25 ten thousand), polyethylene glycol (PEG)6000 (weight average molecular weight 6000, manufactured by Wako pure chemical industries, Ltd., and first grade), aqueous ammonia (manufactured by Kishida chemical Co., Ltd., reagent grade), silica particles (PL-3, manufactured by Hibiscus chemical industries, Ltd.), and ion-exchanged water was diluted 40-fold with ion-exchanged water immediately before use to prepare a final polishing solution. The composition of the fine polishing liquid is as follows.

Hydroxyethyl cellulose: 0.01% by mass

PEG 6000: 0.0008% by mass

Silica particles: 0.17% by mass

Ammonia: 0.01% by mass

(silicon wafer)

Single crystal silicon wafer (silicon single-sided mirror wafer 200mm in diameter, conductive type: P, crystal orientation: 100, resistivity: 0.1. omega. cm or more and less than 100. omega. cm)

(Fine grinding Condition)

Grinder: single-side 8 inch grinder "GRIND-X SPP600 s" (manufactured by Ongben work)

Polishing pad: pile Pad (Suede Pad) (manufactured by Tooli Coatex Co., Ltd., ASKER hardness: 64, thickness: 1.37mm, pile length: 450 μm, opening diameter: 60 μm)

Silicon wafer polishing pressure: 100g/cm ²

Platen rotation speed: 60rpm

Grinding time: 5 minutes

Supply rate of the polishing slurry: 150g/min

Temperature of the polishing slurry: 23 deg.C

Vehicle rotation speed: 62rpm

< 2. cleaning with cleaning member >

Cleaning with a cleaning member, ozone cleaning, and dilute hydrofluoric acid cleaning were performed as 1 set of treatments, and the silicon wafer after finish polishing was subjected to 2 sets of treatments in total. Thereafter, the cleaned silicon wafer was spun at 1,500rpm for 2 minutes to be spin-dried. The conditions for each cleaning were set as follows.

In the cleaning using the cleaning member, ultrapure water was injected at a flow rate of 1L/min to the central portion of a silicon wafer rotating at 600rpm, and the cleaning member of the example or comparative example was moved from the central portion to the outer peripheral portion of the silicon wafer and pressed against the same, thereby cleaning each surface of the wafer. The cleaning time was set to 1 minute.

In the ozone cleaning, ozone water at room temperature (23 ℃) containing 20ppm of ozone was sprayed at a flow rate of 1L/min to the center portion of a silicon wafer rotating at 600rpm for 3 minutes.

In the dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5 mass% ammonium bifluoride (reagent grade, manufactured by Nacalai Tesque corporation) at room temperature (23 ℃) was sprayed at a flow rate of 1L/min onto the center portion of a silicon wafer rotating at 600rpm for 6 seconds.

< 3. measurement of surface Defect >

The surface defects of the cleaned silicon wafer were evaluated by measuring the number of fine particles having a particle diameter of 45nm to 50nm on the surface of the silicon wafer using a "Surfscan SP 1-DLS" apparatus manufactured by KLA Tencor. The evaluation result of the surface defect was evaluated based on the value of a dark field oblique beam composite channel (DCO) measured using the above-described apparatus. The smaller the value, the less surface defects.

The number of surface defects generated in the silicon wafer during cleaning using the cleaning members of example 1 and comparative example 1 is shown as a result in (a) and (b) of fig. 5. In fig. 5 (a), the smaller the number of white spots in the inner black region surrounded by the circle, the less surface defects are generated, and the more excellent the cleaning performance of the fine particles is.

As shown in FIGS. 5 (a) and (b), it was confirmed that the cleaning member of example 1 had less residual particles on the surface of the silicon wafer and less surface defects than the cleaning member of comparative example 1. Therefore, the cleaning member of the present invention is excellent in the cleaning performance of the fine particles, and is particularly suitable for cleaning precision electronic components such as substrates for which effective removal of the fine particles is desired.

Industrial applicability

According to the present invention, there is provided a cleaning member having excellent cleaning performance of fine particles adhering to a surface to be cleaned.