JPH02218561A - Manufacture of abrasive cloth - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a polishing cloth which is made of a nonwoven fabric made of synthetic fibers and has good polishing efficiency and less clogging.

(Prior art) Conventionally, non-woven fabric is impregnated with polyurethane as a primary polishing cloth for polishing the surfaces of plate glass, metals, semiconductors, ceramics, etc. to obtain ultra-precise surfaces, and is obtained by desolventizing and coagulating in water. A polyurethane porous body containing fine #I pores is bonded to the sheet, which is then sliced to an appropriate thickness. The polishing cloth thus obtained is widely used because the fine pores of the porous polyurethane material are suitable for retaining an abrasive liquid containing abrasive grains and at the same time discharging abrasive debris.

(Problem to be solved by the present invention) However, since the pores of the polyurethane porous material have a small diameter, they quickly become clogged with polishing debris during polishing work, and the dressing cycle required to maintain a constant polishing efficiency is required. There are problems such as shortening the life of the polishing cloth itself, and this tendency becomes even more obvious when high-pressure, high-speed polishing is required, or depending on the type of object to be polished.Therefore, there is a strong demand for improvement. has been done.

As a solution to these problems, clogging can be eliminated by reducing the amount of polyusotane, but the retention of the abrasive liquid becomes insufficient and the polishing efficiency decreases.

In addition, a method has been proposed in which a sheet made by impregnation and wet coagulation is heated without pressure for a certain period of time above the softening temperature of polyurethane. Not only are there problems such as the range of temperature and time conditions for obtaining the pore size being narrow and yellowing of the polyurethane due to high temperatures, but the effects are not so great.

The present invention solves these problems and aims to provide a method for producing a clogging-free polishing cloth without reducing polishing efficiency.

(Means for Solving the Problems) The present invention impregnates a high-density nonwoven fabric made of synthetic fibers with different solvent properties from polyurethane with a polyurethane solvent solution,
Next, wet coagulation and drying are performed to form a polyurethane porous body with fine pores integrally fixed (5/ ), which is sliced to a predetermined thickness, and then a polyurethane solvent is applied and a dry heat treatment is performed. A method for producing an abrasive cloth characterized by:

The present invention will be explained in detail below.

The synthetic RB nonwoven fabric used in the present invention may be made of any synthetic fiber such as polyester or polyamide as long as it has different solvent properties from polyurethane.

Further, the fiber form may be either a staple or a filament. The thickness of the nonwoven fabric is also not particularly limited, but from the viewpoint of production efficiency in the slicing process described below, a high density nonwoven fabric with a basis weight of 300 to 1000117 m2 is preferable.The polyurethane solvent solution to be impregnated into the nonwoven fabric is Known polyether-based or polyester-based polyurethanes and their solvents are used, and optional components other than polyurethane, such as coagulation aids and foam stabilizers, may be added as necessary.

The nonwoven fabric impregnated with a polyurethane solvent solution undergoes coagulation, water washing, and drying steps using a known wet method to obtain a sheet in which the polyurethane porous body containing fine pores is integrally bonded and fixed to the nonwoven fabric. . The surface layer of the obtained sheet is removed and the sheet is sliced to a required thickness, generally 1 to 2 sm.

In the present invention, the sheet obtained by slicing in this manner is further treated with a polyurethane solvent.

The solvent for polyurethane is dimethylformamide,
A solvent such as methyl ethyl ketone or dioxane or a mixed solvent with water, isopropyl alcohol, toluene or the like is used.

Methods for applying solvent to the sheet include coating method, spraying method,
Any method such as a dipping method or a printing method can be used. It is preferable to use the solvent after diluting it with water etc. to the required concentration.
In this case, the degree and speed of dissolution can be arbitrarily controlled to stably obtain a cell shape with delicate pores.

In the sheet to which the solvent has been applied, the countless fine pores inherent in the polyurethane porous material are partially dissolved and the pores are integrated, expanding the pore diameter and making the independent pores continuous, thereby improving the ventilation of the sheet. The degree becomes large.

This air permeability can be controlled by appropriately adjusting the amount of solvent depending on the use of the polishing cloth.

The sheet to which the solvent has been applied can then be dried to form the desired polishing cloth, but if necessary, it is also possible to use a curing agent, an antistatic agent, etc. at the time of applying the solvent to perform curing, etc. be. Also, implementation of the invention may be continuous or discontinuous.

(Example) The present invention will be explained below with reference to Examples.

Example Thickness 5 layers made of polyester short fibers, date 70017
A high-density nonwoven fabric of 1.5 mm was impregnated with a polyurethane-based solution containing dimethylformamide (D 1) as a solvent (the amount of adhesion was set at 2 levels, 50 wtt4 and 70 wt. in resin solid content), and this impregnated V-t was The polyurethane was wet-coagulated by immersion in water, then washed with water to remove the solvent, and then dried to produce a sheet in which a polyurethane porous body containing numerous fine pores was bonded and fixed.

Thereafter, the surface layer was removed using a slicer, and the sheet was further divided into two parts to obtain a sheet having a thickness of 1.2 cm.

To this, a mixed solvent of DMIF and water (component weight ratio 501
50.30/70 (2 levels) was applied by dipping method, the pick-up rate was 1009G), and internal heating was performed using a far-infrared heater to dry. In addition to measuring the air permeability of this sheet, we also evaluated clogging when actually polishing silicon wafers. The polishing test was carried out under a contact pressure of 5002~ while circulating a polishing liquid containing colloidal silica having an average particle size of 0.05 μm.

Clogging was determined from surface smoothness by touch, coloring state, and visual observation, and was expressed as the time until clogging started (9).

The results are shown in the table below. In the table, the comparative example is the case where no polyurethane solvent was applied.

(Effects of the Invention) In the present invention, micropores in the porous body are partially dissolved by treating a polyurethane porous body integrally fixed with a high-density nonwoven fabric by a wet coagulation method with a polyurethane solvent, By expanding and making it continuous,
The breathability of the polishing cloth can be greatly improved,
The significance of the present invention is great because a polishing cloth with less clogging and no reduction in polishing efficiency, which had been considered difficult, can be obtained.

Agent: Patent Attorney Toshio Yoshizawa

Claims (1)

[Claims] A high-density nonwoven fabric made of synthetic fibers with different solvent properties from polyurethane is impregnated with a polyurethane solvent solution, then coagulated and dried to form a sheet integrally fixed with a polyurethane porous body containing micropores. A method for manufacturing an abrasive cloth, which is characterized by slicing the cloth to a thickness of 100 mL, applying a polyurethane solvent, drying, and heat-treating the cloth.