JPH0625975A - Method for preventing glass cloth for printed wiring board from fraying - Google Patents

Abstract

PURPOSE:To obtain a method for preventing a selvedge part or a cut part of a glass cloth used as a printing wiring board in its state of impregnation with a resin varnish from fraying. CONSTITUTION:The method for preventing a selvedge part or a cut part of a glass cloth from fraying is to impregnate the fringed selvedge part of the glass cloth woven with a piecemeal loom or the cut part of a cut glass cloth with a solution of a copolyester resin having >=100 deg.C softening point and a specific composition in a chlorinated hydrocarbon solution as a solvent at a ratio so as to provide the substantial same thickness of the cloth after applying the resin as that of the cloth before applying the resin, then volatilize the solvent and heat-treat the glass cloth or impregnate the glass cloth therewith, volatilize the solvent, heat-treat the impregnated glass cloth and subsequently cut the heat-treated glass cloth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing fraying of a glass fabric used as a printed wiring board in a form impregnated with a resin varnish.

[0002]

2. Description of the Related Art Conventionally, glass woven fabrics were often woven by a shuttle looms, but in recent years, fragmentary looms called innovative looms have been developed and have rapidly spread due to their efficiency and good quality. is there. The glass fabric woven by the fragment loom is
Different from the weft weaving machine, in which wefts are folded at the end of the fabric to form adjacent wefts, each weft is independently wefted with a certain length, and then cut slightly longer than the width of the fabric at the end of the fabric. It forms a so-called "tassel ear". When the glass fabric having such tufts is used for resin varnish impregnation, the tufts are impregnated with a large amount of varnish. Further, since this portion must be cut, it is not preferable in terms of cost and process. Another drawback of the tufted ear is that the weft yarn is not folded back, so that the warp yarn is easily unraveled during the varnish impregnation process, which causes a problem of winding the roll yarn. It has been difficult to solve this problem at the same time because the fraying is more likely to occur as the length of the tuft is shortened as much as possible in order to reduce resin loss in the tuft. On the other hand, not only the fabric woven by the fragment loom, but also the fabric woven by the shuttlecock fabric is often used by dividing it into two or three parts. The warp easily frays when it is cut.

[0003]

In order to prevent the above-mentioned fraying, it has been considered to cut the tufts or the base of the fabric while melting and adhering the glass yarn with a laser beam.
However, the melting adhesive strength with a laser is weak, and the adhered part easily peels off against strong ironing, or the molten glass forms minute spheres that fall into the varnish bath during the resin varnish impregnation process. It has drawbacks and is not a complete countermeasure.

On the other hand, attempts have been made to prevent fraying by applying a hot-melt adhesive to the tufted ear portion, the cut tufted ear portion or the cut portion. However, the resin varnish contains acetone, methyl ethyl ketone, methyl cellosolve, methanol, ethanol, dimethylformamide,
A wide variety of organic solvents such as toluene and hexane are used, and if the adhesive dissolves in these solvents in the varnish bath or after impregnation with the varnish, the performance of the varnish may be affected. Especially for glass fabrics for varnish impregnation used in fields where high quality assurance is required, such as printed circuit boards, it is essential that the adhesive does not elute, but the ethylene-vinyl acetate copolymer that has been commonly used in the past has been essential. Alternatively, a copolymer containing a polyamide as a main component obtained by reacting a polymerized fatty acid with an aliphatic amine does not have sufficient solvent resistance and cannot be used.

It has also been attempted to use a thermosetting resin such as an epoxy resin or a phenol resin for the adhesive. Although these thermosetting resins have relatively good chemical resistance, it takes a considerable amount of time to cure after being applied to the glass cloth, and it cannot be said that they are necessarily satisfactory in terms of equipment and productivity.

Further, attempts have been made to melt and heat a thermoplastic resin such as nylon 6, nylon 66, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene ether, or to extrude it in a minute amount, or to bond it by forming a film. However, since these resins have a relatively high melting point and a high melt viscosity, it is difficult to apply and impregnate a very small amount of a resin onto a glass woven fabric at a considerably high degree. According to the research conducted by the present inventors, this method is possible only when the melting point of the thermoplastic resin is 200.degree.
It is necessary that the melt viscosity at 0 ° C is not more than 500000 centipoise. In this case, if the impregnation is insufficient, the fluff of the glass yarn may occur from the cut portion, and since the fabric thickness of the coated portion becomes significantly thicker than other portions, the glass fabric is wound on a roll. When taking it, it causes problems such as so-called “ear height”. At ear height, it cannot be wound to the desired length. If it is wound with a strong tension, the glass fabric is likely to be broken at the ears, and if it is wound loosely, the texture is broken and the product does not have good morphological stability.

After all, if a large amount of the anti-raveling agent is applied, the anti-raveling effect is great, but as described above, there is a great difficulty in winding in a roll form. On the other hand, if the application amount of the anti-raveling agent is small, the hindrance of the roll winding is eliminated, but there is a contradiction that a sufficient anti-raveling effect cannot be obtained.

Further, the conventionally used adhesive such as ethylene-vinyl acetate copolymer has a drawback that it has a long open time when applied in the form of an organic solvent solution.
That is, when a solution of a commonly used adhesive agent such as an ethylene-vinyl acetate copolymer is applied to a glass fiber woven fabric, this solution does not easily solidify, and the adhesive agent retains its tackiness for a long time, so that it is rolled into a roll form. When taken, there is the problem that adjacent glass fiber fabric layers adhere to each other.

The present invention solves various problems of the conventional anti-fraying method for glass fabrics, has an excellent anti-fraying effect, and has problems such as "ear height" and varnish bath contamination which occurs when impregnating varnish. It is an object of the present invention to provide a method for preventing fraying of a glass fabric for printed wiring boards, which can be carried out industrially and economically.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied a glass fabric anti-raveling method that completely overcomes the above-mentioned drawbacks of the conventionally known glass fabric anti-fraying method. It has been found that it is very effective to apply one kind of copolyester resin in the form of an organic solvent solution and to perform a heat treatment, and have completed the present invention.

That is, in the anti-fraying method for glass fabric according to the present invention, 40 to 90 mol% of the carboxylic acid component is terephthalic acid, 10 to 60 mol% of isophthalic acid and saturated fat having 4 to 20 carbon atoms. At least one dicarboxylic acid component selected from the group dicarboxylic acids and 2 to 2 carbon atoms
A copolyester resin composed of at least one glycol component selected from 10 alkylene glycols, which has a softening point of 100 ° C or higher and a chrominated hydrocarbon solution The tufts of the glass fabric woven by the fragment weaving machine or the cut parts of the cut glass fabric are impregnated in a proportion that is substantially the same as the fabric thickness before resin application, and then the solvent is volatilized and heat treated. It is characterized in that it is carried out or impregnated with a glass woven fabric, then the solvent is volatilized and a heat treatment is carried out and then the cutting is carried out.
The glass fabric which has been subjected to the anti-fraying method according to the present invention is particularly useful as a glass fabric for impregnating varnish.

In the copolyester resin used in the present invention, the dicarboxylic acid component constituting the resin is
Terephthalic acid, isophthalic acid and aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as succinic acid, glutaric acid and sebacic acid can be used, and the glycol component is an alkylene glycol having 2 to 10 carbon atoms such as ethylene. Glycol, 1,2-propanediol, 1,3-
Propanediol, 1,4-butanediol, 1,6-
Hexanediol and the like can be used, but are not limited to these examples. These glycol components may be used alone or in combination of two or more. The proportion of terephthalic acid in the total carboxylic acid component is important from the viewpoint of solvent resistance, and when terephthalic acid is less than 40 mol%, it easily dissolves in acetone, methyl ethyl ketone, dimethylformamide, etc. Elution in the process becomes a problem. If the proportion of terephthalic acid in all carboxylic acids exceeds 90 mol%, the solubility in low boiling point organic solvents such as methylene chloride is poor.

To impregnate the glass fabric with the copolyester resin, for example, a method of dissolving it in an organic solvent such as methylene chloride and applying the solution can be employed. The resin is excellent in solvent resistance and is characterized in that it is not eluted in the resin varnish impregnation step, but it is slightly soluble in chlorinated hydrocarbons such as methylene chloride and trichlene. However, in the process of impregnating a glass fabric with a resin varnish, almost no elution is observed, and in the field of using a glass woven fabric as a base material for impregnating a resin varnish, epoxy resin, unsaturated polyester resin, polyimide resin, silicone Resins and the like are well known, but methylene chloride, chlorinated hydrocarbon solvents such as trichlene are rarely used for these, these solvents have a low boiling point and are easily volatilized, and flammability is Since it does not exist, the object of the present invention is sufficiently satisfied. After coating and impregnating the solution, the solvent should be stripped by a suitable method such as exposure to hot air. After volatilization of the solvent, heat treatment is further performed in order to further sufficiently improve the fraying effect. As the method of heat treatment, there can be used a method of exposing to hot air or the like, or a method of applying pressure using a hot roll or the like. It is preferable that the impregnated resin melts once upon heating.

The organic solvent of the copolyester resin is preferably applied along the warp direction to the tufts of the glass fabric or the woven fabric of the glass fabric woven by the fragment loom.
In addition, the application amount is such that the fabric thickness after resin application is substantially the same as the fabric thickness before application so as not to cause so-called “ear height” when winding the glass fabric on a roll. To

Thus, by applying the anti-raveling method of the present invention, a varnish-impregnated glass fabric used as a printed wiring board which requires particularly high quality can be obtained extremely advantageously.

[0016]

The present invention will be described in detail below with reference to the following examples, but the present invention is not limited to the following examples without departing from the scope of the invention.

Example 1 Softening point 173 ° C. composed of dicarboxylic acid component consisting of terephthalic acid 65% by mole, isophthalic acid 10% by mole and adipic acid 25% and glycol component consisting of 1,4-butanediol, A copolymerized polyester resin having a melt viscosity of 400 poise measured by an elevated flow tester at 200 ° C,
It was obtained by carrying out a transesterification reaction, an esterification reaction and a polycondensation reaction using a tetraisopropyl titanate catalyst. The solvent resistance of this resin is shown in Table 1.

[Table 1]

4% by weight of the above copolymerized polyester resin was dissolved in methylene chloride. The solution viscosity was 100 centipoise. This was impregnated by linearly applying it to the center of a 0.2 mm glass woven fabric with a shuttle looms at a rate of 1.5 cc per 1 m and then using a hot air dryer for 1 minute in an atmosphere of 200 ° C. Dried. By this drying treatment, the solvent is volatilized and the resin on the glass fabric after the solvent is volatilized is heat-treated. The spread of the coated part was 7 mm. The center of this coated portion was cut with scissors and the fray of the cut portion was tested, but the fray did not occur at all. In addition, the thickness of the woven fabric at the coated portion was 0.2 mm, which was exactly the same as before coating, and no difference was observed between the adhered portion and the non-adhered portion even when the glass fabric whose fraying was prevented in this example was wound up on a roll. It was

Comparative Example 1 A dicarboxylic acid component consisting of 30 mol% of terephthalic acid, 50 mol% of isophthalic acid and 20 mol% of adipic acid, and 1,4-
A copolymerized polyester resin having a melt viscosity of 450 poise by an elevated flow tester at a softening point of 78 ° C. and 200 ° C., which was composed of a glycol component composed of butanediol, was obtained in the same manner as in Example 1. This copolymerized polyester resin was completely dissolved in methyl ethyl ketone and dimethyl formaldehyde by a dipping test at 20 ° C. for 72 hours.

Example 2 A polyester was produced basically in the same procedure as in Example 1 by changing the kinds and compositions of the dicarboxylic acid component and the glycol component. (Note that manganese dioxide was used as the transesterification catalyst only when ethylene glycol was used as the glycol component, but otherwise, the same trimethyl phosphate as in Example 1 was used.) The compositions and properties of these polyesters are shown in Table 2 and Table 2. 3 shows. Further, these polyesters were applied to a glass cloth in the same manner as in Example 1 to obtain a glass cloth having ears with strong sealing power.

[Table 2]

[Table 3]

Comparative Example 2 Softening point composed of a dicarboxylic acid component consisting of 38 mol% terephthalic acid, 32 mol% isophthalic acid and 30 mol% adipic acid and a glycol component consisting of 100 mol% 1,4-butanediol. A polyester resin having a melt viscosity of 440 poise by an elevated flow tester at 95 ° C. and 200 ° C. was obtained in the same manner as in Example 1. This resin was also completely dissolved in toluene, dimethylformamide and the like.

Comparative Example 3 Dicarboxylic acid component consisting of 100 moles of terephthalic acid and 1,
A polybutylene terephthalate homopolymer composed of a glycol component consisting of 100 mol% of 4-butanediol was obtained in the same manner as in Example 1. The softening point of this resin is
It was 230 ° C. This resin was poorly soluble in methylene chloride and other organic solvents by the method of Example 1.

Table 4 collectively shows the composition and properties of the polyesters used in Comparative Examples 1, 2, and 3.

[Table 4]

Comparative Example 4 A glass fabric was linearly coated with a methylene chloride solution of a copolyester resin in the same manner as in Example 1, and then methylene chloride was volatilized under an atmosphere of 50 ° C. When the center of the applied part was cut with scissors and the fray of the cut part was tested, the effect of preventing fray was slightly weaker than in Example 1, and when the cut part was strongly squeezed, fray occurred.

[0025]

Since the method for preventing fraying of glass fabric according to the present invention is constructed as described above, the anti-fraying at the ears or cut portions of the obtained glass fabric is extremely excellent.
Further, the glass fabric to which the anti-raveling method of the present invention is applied does not cause ear height during winding, and does not contaminate the varnish even when used for impregnating varnish.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B32B 17/04 A D06C 25/00 A // D06M 23/18 (72) Inventor Sonichi Watanabe Shiga Asahi Schebel Co., Ltd., 515 Kojima-cho, Moriyama City, Japan

Claims (1)

[Claims] 1. 40 to 90 mol% of the dicarboxylic acid component is terephthalic acid, 10 to 60 mol% of which is at least 1 selected from isophthalic acid and saturated aliphatic dicarboxylic acids having 4 to 20 carbon atoms. Species dicarboxylic acid component and carbon number 2-10
A chlorinated hydrocarbon solution of a resin having a softening point of 100 ° C or higher, which is a copolyester resin composed of at least one glycol component selected from the alkylene glycols of At a rate that is substantially the same as the woven fabric thickness, impregnate the tufted portion of the glass fabric woven by the fragment loom or the cut portion of the cut glass fabric, and then volatilize the solvent and perform heat treatment, Alternatively, a method for preventing fraying of a glass fabric for a printed wiring board, which comprises impregnating a glass fabric, volatilizing a solvent, performing heat treatment, and then cutting.