JPH06337B2 - Method for measuring dryness of prepreg for laminated board - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the dryness of a prepreg used when manufacturing a laminated board used in electronic devices and the like.

2. Description of the Related Art Conventionally, as a method of manufacturing a prepreg for a laminated board, a two-step coating method has been used in which a phenol resin varnish is used as an undercoat for a substrate and a phenol or epoxy varnish is used as an overcoat. known. In the two-step coating for manufacturing the prepreg for a laminated plate, as a method for confirming the dryness after undercoating, the prepreg after undercoating drying is
It has been general practice to measure the amount of volatile components by heat treatment at 60 ° C. for 10 minutes.

Problems to be Solved by the Invention The confirmation of the undercoat dryness by the above method has the following problems.

(1) When carrying the prepreg after drying the undercoat to an oven for measuring volatile matter (hereinafter referred to as “oven”), or when removing the harmful prepreg from the oven and measuring the volatile matter by the weight difference before and after heat treatment, Moisture in the atmosphere causes the prepreg to absorb moisture, making it difficult to know the true volatile content and causing an error in dryness measurement.

(2) In order to separately heat-treat the prepreg after drying the undercoat, the test piece must be cut out from the prepreg during continuous production. It may cause the interruption of coating production.

(3) In order to measure the amount of volatile matter, the prepreg is usually heat-treated in an oven for about 10 minutes, but it takes 10 minutes or more from the time when the prepreg for measurement is sampled until the amount of volatile matter can be confirmed.

The present invention aims to solve the above-mentioned problems and to measure the amount of volatiles quickly and accurately, and further provides a dry preparative measurement method of prepreg that can contribute to the production of prepreg with stable quality and efficiency. The purpose is to do.

Means for Solving the Problems In order to achieve the above object, the present invention, in the production of a prepreg for lamination using a phenolic resin varnish for the undercoat, by applying a ferric chloride solution to the prepreg after drying the undercoat The degree of coloration is used to measure the dryness after undercoating.

As a method of confirming the dryness of the prepreg after drying the undercoat,
Although the volatile matter amount of the prepreg has been conventionally measured, as a result of investigating the factors related to the volatile matter amount, a correlation between the residual unreacted phenol content in the prepreg and the volatile matter amount was obtained. It is shown in FIG. here,
Based on the conventional knowledge that phenol exhibits a unique color reaction due to ferric chloride, as a result of further study,
It was found that the prepreg after the undercoat was dried was adhered and impregnated with a solution of ferric chloride having a constant concentration, so that the prepreg exhibited a coloration according to the amount of residual unreacted phenol. From these results, the residual unreacted phenol content in the undercoat prepreg can be easily quantified, and the volatile content associated with the phenol content can be immediately measured with less error than the conventional volatile content measurement by the oven method.

The degree of coloration due to this ferric chloride is shown in FIG. The color reaction can be confirmed with the naked eye, but for numerical control, it is preferable to confirm with a device as shown in% of brightness in FIG. 2, and if a side colorimeter or a color difference meter is used, The accuracy is further increased.

According to the present invention, since the volatile matter closer to the true value and the undercoat dryness can be immediately known by coloring due to the above characteristics, the conventional problems, more specifically, when collecting the prepreg for measuring the volatile matter and at the time of weighing are described. Error due to moisture absorption,
Eliminates the problem of labor and time required to measure volatile matter.
Furthermore, during continuous production, the prepreg can be directly impregnated with a ferric chloride solution for coloration, and the problem of interruption of coating production due to prepreg breakage, which was conventionally caused by the collection of measurement prepregs, is solved. To do.

According to the present invention, the punching workability of the laminate, dimensional change, warpage,
It is possible to accurately and effectively confirm the dryness of undercoating which affects characteristics such as color tone by a simple method, and it becomes possible to manufacture a prepreg for a laminated board with stable quality.

EXAMPLES Examples of the present invention and conventional examples will be described below.

Example 1 Phenol-formalin initial condensation resin was mixed with methanol and water (mixing weight ratio: methanol: water = 7: 3) so that the amount of resin adhered to kraft paper having a thickness of 0.1 mm was 10% by weight.
The undercoat varnish diluted with was impregnated and dried. On the other hand, a ferric chloride solution was prepared so as to have a concentration of 35% by weight, and the solution was packed in a hand spray container to prepare a coloring reagent.

Drying is performed so that the undercoat dryness is set to 3.5% volatile matter and 15% residual unreacted phenol content (each weight%). At this time, it is clear from the correlations of FIGS. 1 and 2. In the phenol-ferric chloride coloration reaction, a color difference meter (manufactured by Nippon Denshoku Co., Ltd.) gives a violet color with a lightness of 50%. Continuous production was performed for 24 hours, and a reagent was sprayed on the prepreg during the continuous production every hour, and the drying was adjusted so that the degree of dryness was a set value while confirming the degree of coloration.

Undercoat and topcoat are performed continuously, but after drying the undercoat,
A prepreg for a laminated board was obtained by top coating with a tung oil-modified phenol resin varnish and drying. A laminate of 8 pieces of the prepreg and a 35 μm-thick copper foil placed on the surface of the prepreg were laminated and formed to a thickness of 1.6.
mm single-sided copper clad laminate was produced.

Example 2 Using kraft paper having a thickness of 0.1 mm, an undercoat varnish similar to that in Example 1 and a coloring reagent which is an aqueous solution of ferric chloride, volatile matter and other prepreg characteristics are also the same as in Example 1. to have been subjected to undercoating drying, confirmed by coloring reagent per hour, the measurement prepreg cut taken from the undercoat prepreg 10 cm ^□ during continuous production was performed directly immersed in the reagent were placed in a beaker .

A single-sided copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1.

Conventional Example The same kraft paper and undercoat varnish as in Example 1 were used for undercoat drying. The undercoat dryness was also set to the same volatile content of 3.5% and residual unreacted phenol content of 15%. Undercoat drying A prepreg cut from a prepreg during continuous production to a size of 10 cm ^square is treated in an oven set at 160 ° C for 10 minutes, and the volatile matter is measured and checked every hour to ensure that the dryness reaches the set value. I adjusted. A single-sided copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1.

Table 1 shows the results of the coatings performed in Examples 1 and 2 and the conventional example and the characteristic variations of the laminated plate.

Although the ferric chloride solution used water as the solvent in the above examples, other solvents may be used as long as they dissolve ferric chloride, such as acetone and methanol.

EFFECTS OF THE INVENTION As described above, the present invention relates to the production of a prepreg by a two-step coating using a phenolic resin varnish as the undercoat.
By the very simple method of confirming the undercoat dryness, which has an important meaning for laminate properties, by the degree of coloration of the ferric chloride solution, it is possible to perform the undercoat dry accurately, efficiently and economically. It is of great industrial value in that it can manufacture a prepreg for a laminated plate with stable quality and a laminated plate.

[Brief description of drawings]

Fig. 1 is a curve diagram showing the relationship between the amount of volatile matter and the amount of residual unreacted phenol contained in the prepreg after drying the undercoat, and Fig. 2 is the amount of residual unreacted phenol in the prepreg after drying the undercoat. FIG. 6 is a curve diagram showing the relationship between the degree of coloration by and ferric chloride.

Claims (1)

[Claims] 1. A method for producing a prepreg for a laminate, which comprises applying a varnish in two steps, an undercoat and an overcoat, and using a phenolic resin varnish for the undercoat, as a means for measuring the degree of dryness after the undercoat. A method for measuring the dryness of a prepreg for a laminate, which comprises applying a ferric solution and observing the degree of coloration.