JPH07237129A - Foaming elastic grinding wheel - Google Patents

Abstract

PURPOSE:To prevent a metal plate from being scraped in addition to a coating film by forming a foaming elastic grinding wheel to be used for peeling off the coating film of a coated metal plate by using as a connecting agent a polyether polyurethane elastic foaming body for its grinding grains selected from specific grain degrees. CONSTITUTION:This foaming elastic grinding wheel made up of a grinding wheel main body 1 carried on a metal retaining plate 2 is constituted by connecting to each other grinding grains of more than one or two kinds to be selected from the grain degrees of #24-#80 by means of a polyether polyurethane elastic foaming body, and the combination amount of the grinding grains is set within the range of 5-300 pts.wt. in regard to the 100 pts.wt. of a connection agent, and as the grinding grains, a general-purpose natural grinding agent (corundum, emery, garnet or the like) and an artificial grinding agent (silicon carbide, boron nitride, an alumina grinding agent or the like) are used, and as polyurethane as a grinding grain connection agent, a polyether system which makes polyetherpolyol a polyol element is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed elastic whetstone used for peeling a coating film when repairing a sheet metal coated surface.

[0002]

2. Description of the Related Art The peeling of sheet metal coating as described above is usually carried out by polishing with paper (dry type).

A manual power source may be considered as a power source for paper polishing, but from the viewpoint of workability, it is required to attach a paper disk (abrasive paper) to a disk grinder.

[0004]

However, it has been found that the following problems occur when a disk grinder is used as a power source.

That is, the disk grinder has a large torque, and there is a possibility that the sheet metal (body) other than the coating film may be scraped.

Also, there are many steps and recesses in the main body,
It was difficult to remove the coating film from these parts.

Further, in the case of abrasive paper, it is easy to get clogged with paint at an early stage. (In particular, when there is a putty repaired portion, the tendency is remarkable.) In view of the above, the present invention makes it difficult to scratch the sheet metal itself, and it is easy to peel off the coating film at a portion having a step or a concave portion. An object of the present invention is to provide a foamed elastic whetstone with less clogging.

[0008]

The foamed elastic whetstone of the present invention solves the above problems by the following constitution.

A foamed elastic whetstone used for peeling off a coating film when repairing a coated surface of a sheet metal, and having a grain size of # 24.
To # 80, one or more kinds of abrasive grains are bonded and formed using a polyether polyurethane elastic foam having a specific gravity of 0.2 to 0.4 as a binder, and foam elasticity. Whetstone.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the following description, a compounding unit is a weight unit unless otherwise specified.

(1) The foamed elastic whetstone of the present invention is assumed to be used for repairing a sheet metal coated surface.

(2) The foamed elastic whetstone of the present invention has a grain size of # 2.
One or two or more kinds of abrasive grains selected from 4 to # 80 are bonded by a polyether polyurethane elastic foam having a specific gravity of 0.2 to 0.4.

As the abrasive grains, general-purpose natural abrasives (corundum, emery, garnet, silica stone) and artificial abrasives (silicon carbide, boron nitride, alumina abrasives, artificial emery, etc.) can be used.

If the particle size is larger than # 24, the sheet metal base material is easily scratched, and if it is smaller than # 80, the coating film peeling efficiency (polishing efficiency) decreases, which is not desirable.

The compounding amount of this abrasive grain binder is 100
5 to 300 parts (preferably 100 to 270 parts)
Part). If it is less than 5 parts, the coating film peeling ability becomes small,
Further, when it exceeds 300 parts, the compounding amount of the abrasive grain binder becomes relatively small, and it becomes difficult to obtain sufficient abrasive grain holding force.

As the polyurethane as the abrasive grain binder, a polyether type containing a polyether polyol as a polyol component is used. The polyester-based base has poor surface abrasion resistance, and it is difficult to obtain the required flexibility (sheet metal followability). Further, if the specific gravity is less than 0.2, it is difficult to obtain sufficient abrasive grain holding force, and if it exceeds 0.4, the foaming ratio is small and clogging with release coating powder is likely to occur.

The isocyanate component is not limited to aromatic or aliphatic compounds, but for example, general-purpose crude MDI is used.
To use.

Water is usually used as the foaming agent, but freon gas or the like may be used. Further, the impact resilience is 20% or more (desirably 30 to 70%) in a state where no abrasive grains are mixed (fabric).

(3) The foamed elastic whetstone of the present invention is manufactured, for example, as follows.

A predetermined amount of abrasive grains is added to the polyether polyol component (including other subcomponents such as a foaming agent), and the mixture is thoroughly mixed and stirred (for example, 2 minutes), and then a curing agent (isocyanate component).
, Mix and pour into the mold.

When the mixture starts foaming, the mold is closed, and the mixture is left to cure at 80 ° C to 100 ° C for 2 to 3 hours.

Next, after releasing, post-curing, that is, baking (for example, 100 ° C. × 10 hours) is performed. The post-cured molded product is cut into a predetermined shape with a diamond cutter, and the grindstone body 1 is fixed to a metal or glass fiber holding plate with an adhesive (for example, epoxy) and trimmed to finish.

(4) The foamed elastic whetstone thus manufactured is attached to a grinder (sander), and the coating film on the coated surface of the sheet metal is peeled off (dry type). The rotation number at this time is, for example, about 10,000 rpm when the diameter of the grindstone is 100 mmφ.

[0024]

The foamed elastic whetstone of the present invention, due to the above-mentioned constitution, has the following effects as supported by the test examples described later.

(1) It is difficult to damage the sheet metal base material, and the coating film can be easily peeled off from a portion having a step or a recess.

Since the polyether polyurethane has an appropriate elasticity and a proper expansion ratio, even if the sheet metal has a convex portion or a curved surface, each of the abrasive grains works well on each portion of the coating film with an appropriate force. It is presumed that this is because the coating film is peeled off.

(2) There is little clogging of the grindstone. It is presumed that since the binder is an elastic foam, the coating powder separated on the surface is sequentially captured and discharged due to the pores of an appropriate size.

(3) The peeling boundary portion of the coating film has a cross section in which the coating film gradually decreases, and no post-processing is required. The reason is the same as the above (1).

[0029]

[Test example]

(1) Example White corundum mixed abrasive grains (# 36: 50%, # 4
250 parts of 6: 25%, # 60: 25%) are bonded and molded with 100 parts of polyether polyol (100 mmφ).
X8 mmt), and the foamed elastic whetstone of the example was manufactured. The foam grindstone is a disk grinder "S1-2500".
The product was attached to (Shinano Co., Ltd.), and the coating film was peeled off from the coating surface of the automobile door (coating thickness 80 μm) at 11000 rpm. It should be noted that putty is applied to the concave portion of the base under the repair coated surface.

(2) Comparative Examples 1 and 2 For comparison, a disk sander "S1-2026" (Shinano) having paper disks (125 mmφ) of # 36 (Comparative Example 1) and # 60 (Comparative Example 2) attached thereto was used. (Manufactured by Mfg. Co., Ltd.) was used and the coating was peeled off at 4000 rpm in the same manner as in the above example.

(3) The test results were as follows.

The working speed of the example is the same as that of the comparative example 2 (# 6).
It was faster than 0) and equivalent to Comparative Example 1 (# 36).

In each of Example and Comparative Example 2, the peeled surface was uniform with no coating residue.

The concave portion (particularly a small portion) is a comparative example 1.
No peeling was possible in No. 2, but it could be easily peeled in the example.

Although the step portion of the reinforcing rib of the door can be easily dropped in the example, it was difficult to peel it in the comparative examples 1 and 2.

In the peeled iron plate, fluff was conspicuous in Comparative Examples 1 and 2, whereas in the example, the scratches were about # 180 to # 240, and no deep scratches were formed.

Compared to Comparative Example 2, the Example has 40 to 50
The durability was doubled. That is, in the example, although the peeling efficiency did not change with time (the ability does not decrease to the end),
In Comparative Example 2, the peeling efficiency dropped sharply in 2 to 3 minutes. In the embodiment, the working speed is faster after 1 to 2 minutes have passed since the beginning of use, and it does not change thereafter.

In Comparative Example 2, the putty portion was somewhat entangled (the putty was welded to the paper disc),
In the example, the putty portion was not entangled at all, and could be uniformly polished.

Compared to Comparative Example 2, the Example has no vibration and chatter against the hand even if the rotation speed is high, and
There was no jarring metallic sound generated in Comparative Example 2, and no bad odor like a rubber grindstone was generated.

The temperature rise of the iron plate was the same in both Examples and Comparative Examples 1 and 2.

[Brief description of drawings]

FIG. 1 is a perspective view of a foamed elastic grindstone showing an example of the present invention.

[Explanation of symbols]

 1 Grindstone body 2 Metal holding plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Matsuzaki Profit 732, 1632 Nishihorie, Shinkawa-cho, Nishikasugai group, Aichi Prefecture (72) Inventor Mikio Matsuzaki 1-2-6 Yokoshirohigashi-cho, Kokuraminami-ku, Kitakyushu City

Claims (4)

[Claims] 1. A foamed elastic whetstone used for peeling a coating film when repairing a sheet metal coated surface, wherein one or more abrasive grains selected from grain sizes # 24 to # 80 are used. A foamed elastic whetstone, which is formed by bonding using a polyether polyurethane polyurethane foam having a specific gravity of 0.2 to 0.4 as a binder. 2. The foamed elastic whetstone according to claim 1, wherein the content of the abrasive grains is 5 to 300 parts by weight with respect to 100 parts by weight of the binder. 3. A method of peeling a sheet metal coating film with a foamed elastic grindstone when repairing a sheet metal coated surface, wherein the foamed elastic grindstone has one or more kinds of abrasive particles selected from particle sizes # 24 to # 80. A sheet metal coating film peeling method, wherein particles are used which are formed by bonding using a polyether polyurethane elastic foam having a specific gravity of 0.2 to 0.4 as a binder. 4. The sheet metal coating film peeling method according to claim 3, wherein the content of the abrasive grains is 5 to 300 parts by weight with respect to 100 parts by weight of the binder.