JP2000002649A - Method and device for testing friction coefficient of macromolecular material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the friction characteristics of a macromolecular material, by pressing the tip of a feeler onto the surface of the thin film of the macromolecular material with a specific force, and measuring a friction counterforce being generated by the relative reciprocating movement between the feeler and the thin film. SOLUTION: A stiff plate 3 where a thin film 3 of a required macromolecular material is formed by deposition or the like is attached to a specific position on a movable arm 2. Then, at least one or a plurality of feelers 4 are brought into contact with the surface of the thin film 3 by operating a heavy weight 11, and a specific press load is applied to the thin film 3. Then, while the feeler 4 and the thin film 3 are maintained to be in contact each other, the movable arm 2 is reciprocated up and down or left and right with a specific amplitude, and friction counterforce being generated in a rod 6 due to the reciprocating movement is measured by a load sensor 7 being provided at the middle part of the rod 6, thus eliminating the influence of the internal deformation of a macromolecular material, accurate measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for testing a coefficient of friction suitable for measuring a frictional property, a loss coefficient, and the like of a polymer material such as rubber and plastic, especially on its surface and in the vicinity thereof. It is about.

[0002]

2. Description of the Related Art As a method for testing the viscoelasticity of a polymer material, for example, a vulcanized rubber, a spectrometer (ISO 466) is used.
4) There are methods using other devices, all of which are test methods using so-called bulk samples.
For this reason, any physical property value obtained using a spectrometer or the like includes the influence of the friction coefficient of both the inside and the surface portion of the bulk sample.

[0003]

When it is necessary to determine the frictional characteristics only on the surface of the polymer material or in the vicinity thereof, the required physical property values can be determined with high accuracy by the conventional test method. It was virtually impossible.

[0004] Therefore, the present invention provides a friction property of only the surface of a polymer material and a portion, which is called a surface region, having a depth of about 20 nm, which is considered to be where molecular chain ends of the polymer are gathered. Provided are a method and an apparatus for testing a friction coefficient of a polymer material which can be obtained with high accuracy.

[0005]

According to the method of the present invention for testing the coefficient of friction of a polymer material, at least one, for example, 1 to 10 stylus tips are pressed against a thin film of the polymer material. It is characterized in that either one of the thin film or the stylus is reciprocated in the direction perpendicular to the axis of the stylus in the contact state, and the friction reaction force generated on the other side with this reciprocation is measured. Is what you do.

According to this, for example, the tip of a stylus is pressed against a thin film of a polymer material such as a spin coat layer or a vapor deposition layer with a required force, and under such a condition, either the thin film or the stylus is pressed. By measuring the friction reaction force generated on the other side based on one reciprocating motion, it is possible to obtain the friction characteristics at a position very close to the surface of the material and the viscoelastic characteristics based on the friction characteristics.

By the way, in the surface region of the polymer material where the molecular chain ends of the polymer are considered to be gathered, the molecular mobility of the molecular chain ends is high, and the glass transition temperature is lower than that inside the polymer material. As a result, the following differences occur between the frictional force and the viscoelastic properties from the inside. That is, regarding the frictional force, due to the difference in molecular structure between the two, in the surface region of the polymer material, if the pushing load of the stylus is reduced to reduce the amount of pushing of the stylus, the frictional force becomes the adhesive friction. Is affected by the composition of the stylus, it is no longer proportional to the stylus indentation load, and the viscoelastic property is also the viscoelastic behavior when the temperature is increased due to the difference in glass transition temperature based on the difference in molecular structure. Are significantly different, and the polymer material surface and surface area will exhibit more viscous behavior. Therefore, by using this friction coefficient test method to determine the friction characteristics of the surface region of the polymer material, the friction coefficient of the surface region of the polymer material, which is considered to be where the molecular chain ends of the polymer are gathered, is accurately measured. be able to.

Here, when the number of styluses is increased, the relationship between the hardness of the polymer material and the stylus pressing force becomes
The pressing force per unit area is fixed, and the total pressing force,
That is, the pushing load of the stylus can be increased, thereby increasing the measurement accuracy. Also here, by reciprocating the thin film or stylus,
The reciprocating motion amount and the friction reaction force can be detected as waveforms, whereby the viscosity characteristics of the surface region can be known.

In this friction coefficient test method, it is preferable to determine the loss coefficient of the polymer material based on the phase difference between the cycle waveform of the reciprocating motion and the cycle waveform of the friction reaction force. Can be obtained almost directly from the measured data with high accuracy without performing any special calculation or the like.

[0010] In this test method, more preferably, the amount of pushing of the stylus and the pushing load are minimized. According to this, it is possible to suppress the internal deformation of the polymer material to a negligible level and advantageously remove the influence thereof, and effectively extract the influence of the cohesive friction on the material surface.

Further, the apparatus for testing the coefficient of friction of a polymer material according to the present invention is provided with a glass plate or other rigid plate for supporting a thin film of a polymer material, and at least one stylus for pressing the tip against the thin film. For example, 1 to 10 tungsten styluses are provided, and advancing / retreating means for providing relative approach and separation displacement between the stylus and the thin film are provided, for example, on the rigid plate side. A driving means for reciprocating one of them in a direction orthogonal to the axis of the stylus is provided, and a load sensor for measuring a friction reaction force generated on the other side is provided.

According to this, the test method described above can be properly performed, and by the action of the reciprocating means,
The degree of pushing the stylus into the thin film can be appropriately adjusted.

[0013] In this apparatus, preferably, a moving means for changing the contact position of the stylus with the thin film in at least one of two-dimensional directions is provided. Make it possible.

[0014] Preferably, a displacement sensor is provided for measuring the amount of change in the contact position of the stylus caused by the moving means, so that the friction coefficient can be measured at the expected position of the thin film. Here, more preferably, the displacement sensor can measure the stroke amount of the reciprocating motion.

[0015] Preferably, a thermostat is provided surrounding the rigid plate, and finally the thin film of the polymer material and the stylus deposited thereon, and the temperature of the thin film is prevented from changing under the action of the thermostat.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing an embodiment of the present invention. In the figure, 1 is a rigid plate made of a glass plate or the like that supports a thin film of a polymer material, 2 is a movable arm that fixes the rigid plate 1 in a vertical posture, and 3 is the surface of the rigid plate 1. 2 shows a thin film of a polymer material having a thickness of 1 to 1000 μm, for example, which is fixed.

In this case, at least one stylus, usually in the range of 1 to 10, which is arranged horizontally toward the rigid plate 1 is held at the lower end of a rod 6 hanging down from the upper frame 5. In the middle part of the rod 6, the stylus 4,
Consequently, a load sensor 7 for measuring a friction reaction force acting on the rod 6 is provided. The load sensor 7 can also be provided on the movable arm 2 on the condition that the rod 6 performs a reciprocating motion that generates a frictional reaction force.

On the other hand, the base 8 to which the movable arm 2 is attached is fixedly provided on the lower frame 10, and the stylus 4
Is pressed against the thin film 3 with a required force by using a horizontal sliding guide 9 provided at the lower end of the rod 6.
The horizontal displacement of the stylus 4 can be ensured, and the stylus portion can be moved by pulling the stylus portion toward the thin film with a weight 11 having a required weight.

Here, a driving means for reciprocating the movable arm 2 in one of two-dimensional directions, that is, in the vertical direction in the figure, while maintaining the contact state between the stylus 4 and the thin film 3.
12 is disposed in the base 8, and at the same time, the contact position of the thin film 3 with the stylus 4 is set in at least one of two-dimensional directions, that is, at least one of the vertical direction in the drawing and the direction perpendicular to the paper surface. The moving means (not shown), which is changed to, is also provided in the base 8.

Further, at least one of the respective displacement amounts of the thin film 3, based on the respective actions of the driving means 12 and the moving means, in particular, the reciprocating displacement amount by the driving means 12 is a predetermined constant amount. In this case, a displacement sensor 13 for measuring the displacement of the thin film 3 by the moving means, for example, an optical fiber displacement sensor, is disposed at an appropriate position, in the lower frame 10 in the figure.

Further, here, a thermostatic bath 14 surrounding each of the rigid plate 1 and the stylus 4 is provided, whereby
This prevents the thin film 3 supported by the rigid plate 1 from being affected by the outside air temperature.

By the way, in the above description,
When a load sensor of the piezoelectric element type is used as the load sensor 7, even a small friction reaction force of about 0.001 to 50 gf can be accurately measured, and a moving coil is used as the driving means 12 for causing reciprocating motion. When used, the amplitude of the reciprocating motion can be made much smaller than when using a motor, a hydraulic mechanism, a pneumatic mechanism, or the like.

When measuring the friction coefficient of a polymer material using such a test apparatus, a rigid plate 1 on which a thin film 3 of a required polymer material is formed in advance by, for example, vapor deposition.
At a predetermined position of the movable arm 2, and then the weight
Under the action of 11, the stylus 4 is brought into contact with the thin film 3, thereby causing a predetermined amount of pushing and a pushing load of each stylus 4 into the thin film 3.

Thereafter, the thin film 3 is reciprocated with a predetermined amplitude together with the movable arm 2 and the rigid plate 1 by the operation of the driving means 12, and the frictional reaction generated on the stylus 4 by the reciprocation is detected by the load sensor 7. Measured by Here, as described above, the amplitude of the reciprocating motion can be measured by the displacement sensor 13.

FIG. 2 is a graph showing the friction reaction force measured as described above in relation to the vibration speed of the reciprocating motion. In the drawing, the broken line indicates the vibration speed of the thin film 3, and the solid line indicates the stylus 4. The frictional reaction force acting on each is shown. In such a graph, when the phase difference δ on the coordinate axis between the cycle waveform of the reciprocating motion and the cycle waveform of the frictional reaction force is obtained, the loss coefficient (tan δ) of the thin film 3 is calculated from the phase difference δ. It can be obtained almost directly with high accuracy.

Here, from the measured friction reaction force,
Calculation of required friction characteristics, for example, a friction coefficient, can be performed as follows. Friction coefficient = Friction reaction force ÷ Indentation load

In this apparatus, the contact position of the thin film 3 with the stylus 4 is changed by moving means (not shown) provided in the housing 8 to move the thin film 3 up, down, left or right. The displacement can be performed by monitoring the displacement amount by the displacement sensor 13. In addition, thin film 3
The pushing amount and pushing load of the stylus 4 into the thin film 3 can be changed by displacing the horizontal position of the thin film 3 by the reciprocating means 9 and changing the number of the stylus 4 pushed into the thin film 3, respectively. Here, when the indentation amount and the indentation load are both minimized, the influence of the internal deformation of the thin film 3 is more effectively removed,
The friction characteristics in the surface region of the thin film 3 can be obtained more accurately.

[0028]

As described above, according to the present invention, the relative reciprocation of the stylus is performed while the stylus is pressed against the surface of the thin film of the polymer material with the required amount of pushing and the pushing load. By measuring the friction reaction force generated thereby, the influence of the internal deformation of the polymer material can be removed, and the friction characteristics of the surface and the surface region can be obtained sufficiently accurately.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of the present invention.

FIG. 2 is a graph showing a friction reaction force in relation to a vibration speed.

[Explanation of symbols]

 Reference Signs List 1 rigid plate 2 movable arm 3 thin film 4 stylus 5 upper frame 6 rod 7 load sensor 8 base 9 sliding guide 10 lower frame 11 weight 12 driving means 13 displacement sensor

Claims (7)

[Claims] In a state where the tip of at least one stylus is pressed against a thin film of a polymer material, one of them is reciprocated in a direction orthogonal to the axis of the stylus,
A friction coefficient test method for a polymer material, wherein a friction reaction force generated on the other side of the reciprocating motion is measured. 2. The friction of a polymer material according to claim 1, wherein a loss coefficient of the polymer material is obtained based on a phase difference between a cycle waveform of the reciprocating motion and a cycle waveform of a friction reaction force. Coefficient test method. 3. The method for testing a friction coefficient of a polymer material according to claim 1, wherein the amount of pushing and the pushing load of the stylus are made as small as possible. 4. A rigid plate for supporting a thin film of a polymer material,
At least one stylus for pressing the tip against a thin film of a polymer material, a loading means for pressing the stylus against the thin film, and either the stylus or the thin film perpendicular to the axis of the stylus An apparatus for testing the coefficient of friction of a polymer material, comprising: driving means for reciprocating in a direction; and a load sensor for measuring a friction reaction force generated on the other side. 5. The apparatus according to claim 4, further comprising moving means for changing a contact position of the stylus with the thin film. 6. The apparatus for testing a friction coefficient of a polymer material according to claim 5, further comprising a displacement sensor for measuring at least a change in a contact position of the stylus caused by the moving means. 7. The apparatus according to claim 4, further comprising a thermostat surrounding the rigid plate and the stylus.