JP2746431B2 - Method for measuring the degree of cure of UV-curable resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the degree of curing of an ultraviolet curable resin (hereinafter abbreviated as UV resin) used for a coating material of an optical fiber.
In particular, the present invention relates to a method for measuring the degree of curing of a UV resin, which can grasp the cured state of the surface.

[Prior art] Conventionally, UV resin is generally used as a coating material for optical fibers. The physical properties (Young's modulus, tensile strength, etc.) of the VU resin change depending on the degree of curing, and the change in the physical properties is caused by various factors such as the optical fiber core and the optical fiber coated with the UV resin. Significantly affects characteristics. Therefore, in order to stabilize various characteristics of the optical fiber core wire and the optical fiber strand, it is desirable to keep the degree of cure of the UV resin used for the coating material at an optimum value and to keep it constant.

"Problems to be Solved by the Invention" By the way, the degree of curing of this UV resin depends on the irradiation amount of an ultraviolet lamp, the flow rate or type of purge gas, and the UV level during curing.
Although it depends on factors such as the temperature and pressure of the resin, it is necessary to control and optimize all these factors in order to maintain the curing degree of the UV resin at the optimum value as described above. Is very difficult. Because of this,
A method for quantitatively grasping the curing state of the UV resin is required.

In particular, when the cured state of the surface of the UV resin covering the optical fiber is, for example, when an optical fiber ribbon (hereinafter referred to as a tape ribbon) is formed, the adhesive property between the optical fiber strand and the tape material is determined. When a cable is formed from a tape core, the adhesiveness between the cable constituent material and the tape core or between the tape cores is affected.
Therefore, if the cured state of the surface of the UV resin is not maintained at a constant level, problems such as poor adhesion of the tape core wire or the cable may occur, so it is not possible to grasp the cured state of the surface of the UV resin. is important.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for measuring the degree of curing of a UV resin, which can quantitatively grasp the degree of curing of the UV resin, particularly the cured state of the surface thereof. .

"Means for solving the problem" In the present invention, the adhesive is cured after curing the adhesive on the surface of the UV resin, and then the adhesive strength between the UV resin and the adhesive is measured. The above problem was solved by grasping the degree of curing of the UV resin.

"Action" As the degree of curing of the UV resin progresses, its surface state changes. The change in the surface state is measured by the adhesive force with the adhesive, and the degree of curing of the UV resin, particularly the cured state of the surface, is grasped from the measured value.

Hereinafter, the method for measuring the degree of cure of the UV resin of the present invention will be described in detail.

As described above, the feature of the method for measuring the degree of curing of the UV resin of the present invention is that the adhesive is cured after the adhesive is attached to the surface of the UV resin, and then the cured adhesive and the surface of the UV resin are cured. By measuring the adhesive strength, the degree of curing of the UV resin, particularly the cured state of its surface, is to be grasped.

A specific method of measuring the adhesive force will be described with reference to FIGS.

FIG. 1 shows an optical fiber 1 having a coating layer made of UV resin,
1 shows a sample (hereinafter, referred to as a wire sample) for measuring the adhesive force between an adhesive 1 and an adhesive 2. Less than,
A method for producing this strand sample will be described.

First, two optical fiber wires 1, 1 whose coating layers are made of UV resin are prepared, and these optical fiber wires 1, 1 are arranged close to or in contact with each other such that their end faces face each other. Next, an adhesive is applied between the end faces and on the outer peripheral surface of each end so that the ends of the optical fiber strands 1 and 1 are connected.

As a method of adhering an adhesive between the ends of the optical fiber strands 1 and 1, for example, in the case of an adhesive that cures quickly, the two optical fiber strands 1 and 1 are brought close to each other or A method of supporting in the air so as to abut against each other and attaching the adhesive 2 between the ends in this state is used, and when an adhesive that cures relatively slowly is used,
Even if the adhesive adheres, the optical fiber strands 1 and 1 are arranged on a sheet made of a material such as Teflon that can be easily peeled so that their end faces face each other and are close to or in contact with each other, In this state, a method of attaching the adhesive 2 between the ends and between the ends is used.

It is preferable that the adhesive 2 is adhered on the outer peripheral surface of each end of the two optical fiber wires 1 and 1 such that the respective adhesion areas are substantially equal.

Next, a strand sample is produced by curing the adhesive 2 and peeling off the sheet made of Teflon or the like after the curing, on a sheet made of Teflon or the like.

The adhesive 2 used here is preferably an epoxy, nitrile rubber, chloroprene, polyolefin, vinyl acetate, acrylic, nylon, etc. adhesive having a good adhesive strength to a UV resin. A resin which has very little elongation and deformation of the adhesive when a stress is applied to the subsequent adhesive is suitably used, and a UV resin such as a urethane-acrylate or ester resin is used as the UV resin.

Next, a method for measuring the adhesive force using the strand sample will be described.

First, portions of the optical fiber strands 1 and 1 of the strand sample to which the adhesive is not attached are attached to two fixing jigs. Here, a stress detecting device such as a load cell capable of detecting a stress applied to the fixing jig is attached to one of the fixing jigs. Next, by moving these two fixing jigs in the direction in which they are separated from each other, the optical fiber strand 1 is moved.
Is applied to the surface of the adhesive, that is, the interface between the surface of the UV resin and the adhesive 2, and when a force exceeding a certain stress is applied, breakage is started from this interface, and finally, one of the optical fibers 1 Is pulled out of the adhesive. FIG. 2 shows the state in which it is pulled out. The stress at this time is detected by the above-described stress detection device, and the peak value is measured to obtain an adhesive force (hereinafter referred to as a pull-out force). Here, since this pull-out force differs depending on the contact area between the surface of the UV resin and the adhesive, the contact area of the optical fiber 1 which is pulled out from the adhesive is actually measured, and the pull-out force is divided by this value. Thus, it is necessary to calculate the pulling force per unit area, and to evaluate each sample using this value. In the case of evaluation of a wire sample using the optical fiber 1 having the same shape, the distance in the length direction of the portion of the optical fiber 1 where the adhesive is adhered is used instead of the contact area. Alternatively, the evaluation may be performed using a value obtained by dividing the pulling force by this distance.

Next, a method of measuring the pull-out force using a tape core wire in which the outermost coating layer is a UV resin will be described.

FIG. 3 shows a sample (hereinafter referred to as a core wire sample) for measuring the pull-out force, which is composed of the tape cores 3 and 3 whose outermost coating layer is a UV resin and the adhesive 2. is there. This core wire sample is produced using the same material and method as the above-mentioned strand sample, and the pulling force is measured using the same method as that for the above-mentioned strand sample. That is,
The two tape cores 3, 3 are arranged so that their respective end faces face each other, an adhesive 2 is applied so as to connect the respective end faces, and after curing, the two connected end faces are separated from each other. The pulling force is measured by moving the two tape cores 3, 3 in the direction in which they are to be drawn.

FIG. 4 shows an optical fiber 1 having a coating layer made of UV resin.
A sample for measuring the pull-out force between 1 and the adhesive 2,
3 shows an auxiliary jig sample using the auxiliary jig 4. The auxiliary jig 4 is a hollow cylindrical member made of a material such as a metal and a hardened plastic, which is extremely small in deformation due to stress.

Next, a method for producing the auxiliary jig sample will be described. An adhesive similar to the adhesive used in the above-mentioned strand sample is adhered to the inner peripheral surface of the auxiliary jig 4, and before the adhesive is cured, the optical fiber strands 1, 1 whose coating material is a UV resin.
Are inserted into the auxiliary jig 4 from different end faces. Here, the optical fibers 1 and 1 are inserted into the auxiliary jig 4 so that the insertion amount, that is, the contact area between the optical fibers 1 and 1 and the inner peripheral surface of the auxiliary jig 4 becomes substantially the same. After insertion, the auxiliary jig sample is formed by curing the adhesive.

The pull-out force of this auxiliary jig sample is measured by a method similar to the method used for the above-mentioned core wire sample.

By changing the shape of the auxiliary jig 4, the auxiliary jig sample not only has a pulling force between the optical fiber strands 1 and 1 and the adhesive 2, but also a tape core 3 and the adhesive 2. It can also be used for the measurement of the pulling force.

Next, a method for grasping the cured state of the surface of the UV resin using the pulling force (adhesive force) thus obtained will be described.

Normally, the state of the surface of the UV resin changes as the degree of curing progresses. With such a change in the surface state, the adhesive strength between the UV resin surface and the adhesive also changes. This change in adhesive strength varies depending on the type of adhesive, the type of UV resin, the method of measuring adhesive strength, and the measurement conditions.
When the adhesive strength between the surface of the UV resin and the adhesive is measured using the UV resin under the same measuring method and under the same conditions, the degree of cure of the UV resin and the adhesive strength have a substantially constant relationship. Therefore,
The relationship between the degree of cure and the adhesive strength of the UV resin under certain conditions is determined in advance, and the degree of cure of the UV resin, especially the surface curing, is compared by comparing the data with the adhesive force measured with the sample under the above conditions. Can be grasped.

"Example" A plurality of core wire samples as shown in Fig. 3 were produced using a tape core wire having a urethane-acrylate UV resin coating material and an epoxy adhesive. Each of these core wire samples uses a tape core wire to which a different amount of UV irradiation has been performed, and by measuring the pulling force of each, a UV irradiation amount and a pulling amount as shown by a symbol A in FIG. A relationship with power was obtained. In addition, the gel fraction was measured to indicate the degree of curing of the UV resin in each sample, and the relationship between the UV irradiation amount and the gel fraction as shown by the symbol B in FIG. 5 was obtained.

According to FIG. 5, in this example, the pulling force is about 100 g / mm.
If the degree is about, it is determined that the degree of curing of the UV resin is sufficient.

[Effect of the Invention] The present invention cures the adhesive after attaching the adhesive to the surface of the UV resin, then measures the adhesive strength between the UV resin and the adhesive, and determines the degree of curing of the UV resin from the measured value. This is a method for measuring the degree of curing of a UV resin, which is characterized by grasping. That is, UV
Since the surface state of the resin changes as the degree of cure progresses, the change in the surface state is measured by the adhesive force with the adhesive, and the degree of cure of the UV resin, particularly the surface The cured state can be grasped.

Therefore, according to the present invention, it is possible to easily and quantitatively grasp the cured state of the UV resin, and in particular, since the cured state of the surface of the UV resin can be easily grasped,
By continuously measuring the adhesive force in the manufacturing process and the like, it is possible to stabilize the adhesiveness between the optical fiber and the tape material, for example, in the case of manufacturing a tape core wire. When a cable is formed from a wire, the adhesiveness of the cable constituent material or the tape core wire can be stabilized.

[Brief description of the drawings]

1, 3 and 4 are schematic perspective views showing a sample for measuring the pulling force used in the present invention, and FIG. 2 is a schematic perspective view showing a state where the sample shown in FIG. 1 is pulled out. FIG. 5 is a graph showing the relationship between the UV irradiation amount, the pull-out force and the gel fraction in the example of the present invention. 2 ... Adhesive.

Claims (1)

(57) [Claims] An adhesive is applied to the surface of an ultraviolet-curable resin, and then the adhesive is cured. Then, the adhesive strength between the ultraviolet-curable resin and the adhesive is measured, and the measured value of the adhesive of the ultraviolet-curable resin is used. A method for measuring the degree of curing of an ultraviolet curable resin, wherein the degree of curing is determined.