JPH11248615A - Scratch tester for painted synthetic resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scratch tester which can evaluate scratch resistance of painted film of synthetic resin against the tip of a hard material with fine and detailed reference and good reproducibility. SOLUTION: This scratch tester consists of a test board 22 to hold a specimen 20 and a load arm 24 equipped with a holding part 34 to touchably hold a scratching section 32 having a tip part 32 a in contact with the specimen 20 on the specimen 20. At least either one of the load arm 24 or the test board 52 is linked to a reciprocating movement means 54 so that the load arm 24 and the test board 52 are mutually movable in an axial direction of the load arm 24. In addition, the load arm 24 is placed so as to relatively movable perpendicularly to the test board 52.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scratch tester for evaluating the scratch resistance of a coated synthetic resin molded product and a scratch test method using the tester.

[0002]

2. Description of the Related Art In recent years, synthetic resin molded articles such as side moldings of automobiles have been required to have scratch resistance close to that of sheet metal painting. These synthetic resin molded articles are usually provided with a synthetic resin finish film made of a synthetic resin paint having excellent weather resistance, for example, an acrylic paint.

[0003] On the other hand, in a side molding or the like, after being attached to an automobile, foreign substances adhering to the side molding may be removed by scratching with a nail or the like. In addition, the wax or the foreign matter may be removed from the side molding body 12 and the vehicle body 14 or the metal color trim 16.
May be removed by scratching with a pointed hard synthetic resin plate (squeegee) 18 or the like (see FIG. 1). When scratched with such a pointed object, scratch resistance is required, that is, scratches (conspicuous scratches such as tearing of a coating film) are not required. The behavior of the generation of scratches is different from the behavior of the generation of micro-scratches (abrasion: a reduction in gloss due to diffuse reflection) that occurs when the cloth is wiped with a wax or the like containing abrasive powder.
That is, the synthetic resin molded article is softer than the metal molded article (sheet metal) or the like, and when scratched, the support base is soft even if the coating film has a certain degree of hardness or more. There is a tendency for the coating film to be easily broken.

[0004]

In the above case, it is necessary to evaluate whether or not the synthetic resin finish film formed on the synthetic resin molded article has such scratch resistance. There is.

[0005] As a method of the scratch test, there is a scratch hardness test. For example, Biabaum scratch hardness,
Cohinol degree (see JIS K 5400), Mohs hardness,
Martens scratch hardness.

In the above and cases, when a scratch (exposed substrate) occurs in the coating film by one scratch, the load value is used as a reference. In the above case, when pencils of various hardnesses are used, the pencils are sharpened anew each time they are scratched, so that reproducibility is required.

In any case, it is not assumed that the same portion is caught many times. In the case of a synthetic resin finish coating film, a fine evaluation criterion is required. It is not suitable as a test method for scratching evaluation.

That is, as far as the present inventors know, there is no scratch tester and no scratch resistance evaluation test method capable of evaluating the scratch resistance of a synthetic resin molded product at the tip with good reproducibility on a fine standard.

In view of the above, the present invention provides a scratch tester and a test method for evaluating scratch resistance, which can evaluate the scratch resistance of a synthetic resin coating film on a hard material tip with good reproducibility on a fine basis. Aim.

[0010]

Means for Solving the Problems The inventors of the present invention have been working on the development of a scratch tester that satisfies the above requirements, and have found that a friction tester for a color fastness test disclosed in "JIS L 0823" has been developed. Focusing on, the present inventors have conceived of a scratch tester and a scratch resistance evaluation test method for a coated synthetic resin molded product having the following constitution.

According to the present invention, there is provided a scratch testing machine for a coated synthetic resin molded article, comprising: a test stand for holding a test object; and a holding unit for holding a scratcher having a sharp end so that the sharp end can be contacted on the test object. And a load arm having the following: wherein the load arm and the test table are relatively movable in the axial direction of the load arm, at least one of the load arm and the test table is connected to reciprocating means,
The load arm is disposed so as to be relatively movable in a vertical direction with respect to the test table.

Further, the method for evaluating the scratch resistance of a coated synthetic resin molded article according to the present invention is a method for evaluating the scratch resistance using the scratch tester having the above-mentioned structure. The shape of the contact surface is such that the pointed shape of the scraper is set so as to be a flat shape having a major axis in the axial direction of the load arm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings (see FIGS. 2 to 4).

(1) It is assumed that the scratch tester of the present invention is a tester for evaluating the scratch resistance of a coated synthetic resin molded product.

The scratch tester basically includes a test table 22 for holding a test object 20 and a load arm 24 disposed above the test table 22.

The mode of holding the test object 20 is, for example,
A test object holding groove 28 formed on the test table 22 and a test object fixing member 30 that is slidably fixed in the test object holding groove 28 by screws.

The load arm 24 is disposed so as to be relatively movable in a vertical direction with respect to the test table 22. Specifically, the load arm 24 is hinged at the base end and includes a scratcher holder 34 that holds the scratcher 32 at the distal end.

In the illustrated example, the hinge connection is performed by a fixed shaft 38 bridged between a pair of load arm support columns 36, 36.
The base side of the load arm 24 is supported and formed via a load arm collar portion 24a. Further, from the viewpoint of workability, a balance weight 40 is attached to the base end of the load arm 24 so that the load arm 24 can be maintained in a state where the load arm 24 is rotated about 60 ° upward. A stopper 42 that protrudes between the columns 36, 36 to interfere with the balance weight 40 is provided.

Further, in the illustrated example, the scratcher holding portion 34 is
A set screw 46 provided with a scratcher holding hole 44 for fitting an upper portion of the scratcher 32 and crimping and fixing the scratcher 32;
It is a configuration provided with.

A weight 48 can be attached to the upper end of the scratcher holder 34 by a screw (in the illustrated example, a thumb screw 49) or the like so that the load applied during scratching can be adjusted. Although the specific configuration of the scratcher holder 34 is not shown,
May be rotated so that the angle of the scraper 32 can be adjusted in the reciprocating direction as indicated by a white arrow.

At least one of the load arm 24 and the test table 22 is connected to the reciprocating transport means 50 so that the load arm 24 and the test table 22 can relatively move in the arm extension direction (axial direction) of the load arm 24. Have been.

In the illustrated example, the reciprocating transport means 50 includes a sliding rail 52 on which the test table 22 slides, and an air cylinder 54 for driving the test table 22. The piston rod 56 of the air cylinder 54 is connected to the base end of the test table 22. The drive source of the reciprocating transport means is not limited to an air cylinder, but may be any drive source, such as a screw drive connected to an electric motor. The transfer means may be connected to the load arm 24 side. Further, the test table 22 and the load arm 24 may be independently transferred.

Next, a test method using the above-mentioned scratch test machine will be described.

First, a scratcher 32 made of synthetic resin or metal as shown in FIG. 4 is attached with the load arm 24 turned upward. At this time, the scraper 32 changes the shape of the contact surface between the scratcher 32 and the DUT 20 to the load arm 24.
It is preferable to set the pointed shape of the scraper 32 so as to have a flat shape having a long axis in the axial direction. Thereby, while keeping the scratch area (reciprocating span × contact width in the direction perpendicular to the movement axis) small, the load on the tip of the scratcher 32 due to the reciprocating movement can be reduced, the durability of the scratcher 32 can be improved, and the test can be performed. Can be improved.

When the scratcher 32 is made of synthetic resin,
Use a material having a Rockwell hardness of HRM 70 or more that does not easily cause settling of the point 32a. Specifically, nylon 6, nylon 66 and the like can be suitably used. The shape of the tip 32a of the scraper 32 is such that the taper angle α: 10
１２０120 °, tip R: 0-2.0 mm, tip length (length in the long axis direction) L: 2-20 mm. If the taper angle α is too small, the pointed end portion 32 is easily set, and the scratch test becomes difficult. Conversely, if the taper angle α is too large or the tip R is too large, the test is close to a wear test and does not fall into the category of a scratch test. The specific specifications of the tip 32a when the scratcher 32 is made of metal include, for example, a taper angle α: 90 °, a tip R: 0.1 mm, a tip length (length in a long axis direction) L: 10 mm is preferred.

Then, the test object 20, which is a painted synthetic resin molded product having the synthetic resin coating film 20 a formed thereon, is fitted into the holding groove 28 of the test stand 22, fixed with the stopper member 30 and set.

Subsequently, after the air cylinder 54 is operated to set the piston rod 56 to the rear dead center position, the load arm 24 is lowered.

In this state, the air cylinder 54 is reciprocated at the set speed. Then, as the test table 22 reciprocates, the scraper 28 relatively reciprocates at a set speed while scratching the synthetic resin coating film 20 a of the test object 20.

The test conditions at this time vary depending on the required scratch resistance. For example, the weight is 500 g, the reciprocating span of the test table is 60 mm, and the reciprocating speed of the test table is 50 reciprocations / minute.

By moving the test table 22 back and forth, the scratch test is performed when the substrate is exposed to the test object or when the scratcher 32 is reciprocated a predetermined number of times. finish.

In a test in which the load arm 24 is lifted and the test object 20 is taken out of the test table 22 and reciprocated a predetermined number of times, the presence or absence of a scratch is visually determined.

[0032]

The scratch tester and test method for evaluating scratch resistance of a synthetic resin molded article according to the present invention are based on the above-described structure and method, as shown in the test examples described later, of the hard polymer material tip of a synthetic resin coating film. Can be evaluated with good reproducibility on a fine standard.

[0033]

[Test method] In order to confirm the effect of the present invention, a test piece (width 30 mm x length) prepared from an acrylic coating film formed on a molded article made of a polypropylene composition having each composition shown in Table 1 100 mm × thickness 3 mm) was subjected to a scratch resistance evaluation test under the following conditions.

The method of the present invention: A scratcher made of nylon 6 with a Rockwell hardness of HRM79 and a shape of A = 2
0 mm, B = 32 mm, C = 8 mm, α = 35 °, R = 0, L
= 2 mm. Scratching condition is weight 5
The test table reciprocating span was 60 mm, and the test table reciprocating speed was 50 reciprocations / minute.

Pencil hardness method (degree of kohinol): JIS K 54
Performed according to 00.

Taber clutch method (a type of Mohs hardness method): A scratch test was carried out using a scratcher made of metal plated with tungsten carbide, and the load was evaluated by exposing the substrate. The tester used was a Tabers clutch tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.).

The results are shown in Table 1. It can be seen that the conventional method could not differentiate the evaluation, while the method of the present invention could differentiate and could perform a fine evaluation.

Further, it was confirmed by visual surface observation that the peeling state of the coating film was the same as that of the actual vehicle in the coating film peeling mode performed by the method of the present invention.

[0039]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a sectional view of a mounting mode of a molding which is an example of a product to which the test method of the present invention is applied.

FIG. 2 is a model diagram showing one embodiment of a scratch tester of the present invention.

FIG. 3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a partial perspective view showing the load arm tip side.

FIG. 5 is a perspective view showing an example of a scratcher used in a scratch test of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Side molding main body 20 DUT 22 Test stand 24 Load arm 26 DUT holding means 32 Scratcher 32a Scraper tip 50 Transfer means 52 Transfer rail 54 Air cylinder (drive source)

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroki Hattori 1 Ochiai Nagahata, Kasuga-machi, Nishikasugai-gun, Aichi Prefecture Inside Toyota Gosei Co., Ltd. In company

Claims (2)

[Claims] 1. A scratch tester for evaluating the scratch resistance of a coated synthetic resin molded article, comprising: a test table for holding a test object; A load arm having a holding portion that holds the contact arm so that the load arm and the test table can move relative to each other in the axial direction of the load arm, and at least one of the load arm and the test table reciprocates. A scratch tester for a painted synthetic resin molded product, wherein the load arm is connected to a moving means, and is disposed so as to be relatively movable in a vertical direction with respect to the test table. 2. A method for evaluating scratch resistance using the scratch tester according to claim 1, wherein a shape of a contact surface between the scratcher and the test object is elongated in an axial direction of the load arm. A scratch test method for a coated synthetic resin molded product, wherein the pointed shape of the scratcher is set so as to have a flat shape having an axis.