JP2694773B2 - Method for measuring cell size in foam - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring a bubble diameter in a foam used for process control of a foam molded article and the like.

(Prior Art) Conventionally, as a method of measuring the bubble diameter in a foam, for example, an airtight ring is generally produced and the foaming state is confirmed by the pressure loss thereof. However,
Since it is not possible to directly confirm the bubble state by this method, it is difficult to adapt it in the case of open cells, closed cells, or different resin types. As a method of directly measuring the bubble diameter, the surface or cross section of the object to be measured is observed by a direct reflection light type optical microscope.

Although these methods are simple, it is difficult to focus because the bubble portion is three-dimensional, and furthermore, because the bubble on the surface of the object to be measured and the bubble in the layer below it overlap with each other, a partition wall on the surface of the object to be measured is formed. It is difficult to distinguish the lower bubbles from the partition walls, and in particular, in objective measurement using a measuring device such as Luzex (manufactured by Nireco Corp., image processing device), the bubble diameter may be measured at a value different from the actual value.

On the other hand, the surface to be measured is cut out thinly and the section is observed with a transmitted light optical microscope. According to this method, the influence of bubbles in the lower layer is reduced, and the measurement can be performed by objective measurement using a measuring device.

However, in a substance having a low hardness such as foam, it is difficult to cut the slice into a film thickness that is not affected by the lower layer even if the foam is put under freezing conditions.

(Problems to be solved by the invention) As described above, in the conventional method for measuring the bubble diameter in the foam, the measurement results are likely to vary, skill is required for the measurement, and the objective measurement method can be used. There were problems such as not being.

Therefore, an object of the present invention is to solve these conventional problems and to provide a method for easily and reproducibly measuring the cell diameter in a foam.

(Means for Solving Problems) The above object is achieved by the present invention described below.

That is, the present invention, in the method for measuring the cell diameter of the foam contained in the foam, having a color difference with respect to the resin matrix in the foam of the cut surface and a powder having a particle diameter of 1/100 or less of the cell diameter of the cut surface. It is a method for measuring a bubble diameter in a foam, which comprises filling a bubble portion in a foam, smoothing a surface of an object to be measured, and then measuring a bubble diameter.

(Working) By filling a bubble portion of the foam on the cut surface with a specific powder and measuring the surface of the DUT with a smooth surface, the bubble diameter in the foam can be measured by an objective measuring method.
Measurement can be performed easily and with good reproducibility.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments of the present invention.

In the present invention, the color difference of the powder with respect to the resin matrix means the difference in optical chromaticity when using an optical microscope, and the difference in conductivity when using an electron microscope.

It is preferable that the difference in optical chromaticity is large, for example,
It is preferable that the powder and the resin matrix have a complementary color relationship.

With the difference in conductivity when using an electron microscope, for example,
When the resin matrix is an insulator, a powder having conductivity is selected. In this example, when observed with an electron microscope such as SEM without conducting the conductive treatment, the resin side becomes white, and the powder side filled with bubbles becomes black, and a clear contrast is observed, and the bubble diameter can be measured.

The particle size of the powder used in the present invention is 1 / the bubble size.
It is preferably 100 or less. If the particle size is larger than 1/100, the powder is not accurately filled in the bubbles, and the shadow of the charged powder is also measured at the magnification for measuring the bubbles, which is not preferable.

Any material can be used in the present invention as long as it is a powder having the above functions.

(Examples) Next, the present invention will be described in more detail with reference to Examples.

Conductive sponge with a bubble diameter of about 100 μm (hue: black)
In order to confirm the internal air bubble state, first, a cross section of the sponge is cut out with a razor to prepare a sample section.

Next, this section was used for PMMA (hue;
Put it in a bottle containing white), place the bottle on a 50Hz shaker, and shake for 10 minutes.

After shaking, remove the object to be measured from the bottle and remove the excess PMMA powder adhering to the surface to be measured (sample cross section) with a blade brush.

When this was mounted on a reflection optical microscope and observed at a magnification of 50 times, the partition wall of the bubble was clearly identified.

Furthermore, when a video camera was attached to the eyepiece section and an image signal was input to a Luzex-451 (manufactured by Nireco) for image processing, the number average particle diameter was 84.9 μm (FIG. 1) and the volume average particle diameter was 118 μm (second (Figure) was obtained.

This sample cannot be measured by the above Luzex without being filled with powder.

(Effect of the Invention) According to the method for measuring the cell diameter in the foam of the present invention, the cell diameter in the foam can be measured easily and with good reproducibility by an objective measuring method using a measuring instrument.

[Brief description of the drawings]

FIG. 1 and FIG. 2 show the measurement results by Luzex of the example. Fig. 1; number average distribution Fig. 2; volume average distribution

Claims (1)

(57) [Claims] 1. A method for measuring a diameter of a cell contained in a foam, wherein a foam having a color difference with respect to a resin matrix of the foam on the cut surface and having a particle diameter of 1/100 or less of the cell diameter is foamed on the cut surface. A method for measuring a bubble diameter in a foam, which comprises filling a bubble portion in a body, smoothing a surface of an object to be measured, and then measuring the bubble diameter.