JPH01133738A - Polyester film for printed circuit board - Google Patents

Abstract

PURPOSE:To contrive improvements in bondability of the title film to a conductive layer, resistor layer, insulation layer and printing ink layer, by providing a predetermined coating layer on a biaxially stretched polyester film which has been made a specific center line mean roughness. CONSTITUTION:A biaxially stretched polyester film having centerline mean roughness of 0.02-0.50mum is manufactured by adding inorganic particles (a) to polyester. A coating layer on the surface of the film is formed of the inorganic particles (a) and an ingredient mainly composed of a crosslinked polyester copolymer (b). In the case where a crosslinkable polyester copolymer obtained by grafting acrylic macromer as a polyester copolymer (b), it is preferable to use acrylic resin especially aqueous dispersion acrylic resin. It is preferable if a mean particle diameter (D) of the inorganic particles (a) falls within a range of 0.08-2.2mum and D/d falls within a range of 1.1-80 in relation to a thickness (d) of a coating layer. Then, as the coating layer is applied at least to one side of the polyester film, being stretched and heat treatment is performed, it becomes that thin and uniform coating is possible and crosslinking of the polyester copolymer progresses rapidly and highly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polyester film for wiring boards, more specifically, a polyester film for wiring boards that has improved adhesion to a conductive layer, a resistor layer, an insulating layer, and a printing ink layer. Regarding.

(Prior art) Biaxially stretched polyester films have been used as flexible wiring boards and membrane switches, taking advantage of their excellent electrical insulation, heat resistance, dimensional stability, and chemical resistance. In addition to laminating and latching methods, we also offer conductive paste, conductive ink, resistor ink,
A method of printing insulator ink and marking ink is used. Along with this, a method of providing a thin film of polyester, such as a polyester copolymer, with improved adhesion to various inks (for example, JP-A-62-16
No. 2540) or a method of applying urethane resin (for example, JP-A-62-173253)
is proposed.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional polyester films still have drawbacks such as insufficient adhesion and sticking to each other when annealing to give dimensional stability or heating to harden ink. .

An object of the present invention is to provide a polyester film for wiring boards that has good adhesion to ink or polymer paste for conductors, resistors, or insulators, and does not cause the films to stick to each other.

[Means for solving problems]

In the present invention, at least one side of a biaxially stretched polyester film having a centerline average roughness of 0.02 to 0.50 μm is coated with an average grain size of 0.00 μm. ．． It consists of a component mainly consisting of inorganic particles (a) of 08 to 2.2 μm and a crosslinked polyester copolymer (b), and the average particle diameter (D) of the inorganic particles (a) and the layer thickness (d ) is provided with a coating layer having a ratio (D/d) of 1.1 to 80.

The polyester used in the biaxially stretched polyester film of the present invention is ethylene terephthalate, ethylene α, β
-bis(2-chlorophenoxy)ethane-4,4°-dicarboxylate, ethylene α,β-bis(phenoxy>ethane-4,4-dicarboxylate, ethylene 2,
The main component is at least one structural unit selected from 6-naphthalate units.

Further, other components other than those mentioned above may be copolymerized within a range that does not impede the present invention, preferably within 10 mol%.

The polyester film used in the present invention has the above-mentioned composition as a main component, but within a range that does not impede the purpose of the present invention,
Other types of polymers may be blended, and antioxidants,
Inorganic or organic additives such as heat stabilizers, lubricants, ultraviolet absorbers, nucleating agents, etc. may be added to the extent that they are normally added.

The polyester film constituting the film of the present invention is
It is at least biaxially oriented by a conventional method, and the thickness is preferably 2 to 600 μm, more preferably 25 to 250 μm, and is excellent in practical handling as a base material.

The biaxially stretched polyester film of the present invention has a center line average roughness of 0.02 to 0.50 μm, preferably 0.05 to 0.50 μm.
0.15 μm, more preferably 0°08 to 0.13 μm
It is necessary to be within the range of . If the center line average roughness is too small, the films will easily stick to each other due to heating, which is undesirable. On the other hand, if the centerline average roughness is too large, the uniformity of application of various inks and polymer pastes will deteriorate, and electrical insulation will deteriorate, which is not preferable.

A biaxially stretched polyester film having the above-mentioned centerline average roughness can be produced by a known method such as a method of adding inorganic particles to polyester to form a film.

The coating layer of the present invention consists of components mainly composed of inorganic particles (a) and a crosslinked polyester copolymer (b). The coating layer may contain (a
) and (b) may be added, but (a) and (
The amount of substances other than b) added in the coating layer is less than 40% by weight, preferably less than 20% by weight, more preferably less than 5% by weight.

Substances to be added other than (a) and (b) are not particularly limited, but representative examples include various resins such as urethane resins, non-crosslinked polyester resins, acrylic resins, vinyl resins, styrene resins, antifoaming resins, etc. agent, coating properties improver, thickener, antistatic agent, antioxidant, ultraviolet absorber, dye, pigment, etc., but polyester copolymer (
When using a crosslinkable polyester copolymer grafted with an acrylic macromer as b), it is preferable to use an acrylic resin, particularly a water-dispersible acrylic resin.

Further, the thickness (d) of the coating layer in the present invention is not particularly limited as long as the ratio (D/d) to the average particle diameter (D) of the inorganic particles is 1°1 to 80. 005~0
．． The thickness is preferably 30 μm, and more preferably 0.01 to 0.1 μm.

Here, the crosslinked polyester copolymer is a polyester that is crosslinked by heating, ultraviolet rays, electron beams, etc. by adding a known crosslinking agent that crosslinks the polyester by reacting with the carboxyl group and hydroxyl group at the end of the polyester. Examples include polymers, but particularly preferred are polyester copolymers in which reactive groups are introduced and self-crosslinked either alone or by heating using a crosslinking catalyst.

The former polyester copolymer is a normal polyester copolymer having a carboxyl group or a hydroxyl group at the terminal, and is obtained by polycondensing a dicarboxylic acid component and a glycol component, and is not particularly limited.

The dicarboxylic acid component includes aromatic, aliphatic, and alicyclic dicarboxylic acids, such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid,
Adipic acid, sebacic acid, succinic acid, glutaric acid 19.1
．． Examples include 3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, and azelaic acid. Further, in order to make the polyester copolymer water-soluble or to impart water-based dispersibility, a dicarboxylic acid containing a sulfonic acid metal group can also be used as a copolymerization component. Examples include metal salts of sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoiphthalic acid, 4-sulfonaphthalene 2,7-dicarboxylic acid, and 5(4-sulfophenoxy)isophthalic acid.

The glycol component to be reacted with the dicarboxylic acid mentioned above is an aliphatic glycol having 2 to 8 carbon atoms, or an aliphatic glycol having 6 to 8 carbon atoms.
12 alicyclic gelcols, specific examples include ethylene glycol, 1,2-propylene glycol, 1,3
-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,
2-cyclohexane dimetatool, 1,3-cyclohexane dimetatool, 1,4-cyclohexane dimetatool, Kano xylylene glycol, diethylene glycol,
Such as triethylene gelcol. Polyethylene glycol, polypropylene glycol, and bolite 1 to ramethylene glycol may be used as part of these glycol components.

The polyester copolymer obtained from the above dicarboxylic acid and glycol component is used after being dissolved or dispersed in water, an organic solvent, or a mixed solvent of water and an organic solvent.

These copolymerized polyesters preferably have many terminal groups from the viewpoint of crosslinkability, and have a hydroxyl value of 3 to 200 mgKOH/
g polymer, preferably 5-100 mCIKOH/CI
Made of polymer. When the hydroxyl value is 3 or less, reactivity is poor, and when it exceeds 200, the toughness of the coating film is poor. In addition, the glass transition point of copolymerized polyester is 10 to 90'C.
, preferably from 40 to 70'C, exhibits suitable moisture-resistant adhesion.

The crosslinking agent for crosslinking the polyester copolymer is not particularly limited as long as it reacts with the terminal carboxyl group or hydroxyl group to make it three-dimensional, but representative examples include methylolated or alkylolated urea type, and melamine type. , acrylamide-based resins, polyamide-based resins, epoxy compounds, incyanate compounds, aziridine compounds, and the like. Among these, methylolated melamine and incyanate compounds are preferably used from the viewpoint of adhesion to the substrate, especially wet adhesion. The amount of the crosslinking agent to be added is appropriately selected depending on the type of crosslinking agent, but it is preferably added in an equivalent amount to the terminal amount of the polyester copolymer, and usually 2 to 30 parts by solid content relative to the polyester copolymer. Preferably it is 5 to 20 parts.

Particularly suitable polyester copolymers into which reactive groups have been introduced are the following compounds that have functional groups such as reactive functional groups, self-crosslinking functional groups, and hydrophilic groups in the polyester copolymer that is the backbone polymer. This is what was introduced. Compounds having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and macromers thereof. On the other hand, compounds having an amide group or an alkylolated amide group include acrylamide,
Examples include methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether, ureido ethyl acrylate, and macromers thereof. In addition, as compounds having a hydroxyl group, β-hydroxyethyl methacrylate,
β-hydroxypropyl acrylate-1~, β-hydroxypropyl methacrylate-1~, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-
Hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, etc., and macromers thereof can be excluded.

Examples of compounds having an epoxy group include glycidyl acrylate, glycidyl methacrylate, and macromers thereof. It goes without saying that macromers copolymerized with various types of polymers may also be used.

Among these reactive groups, methacrylic acid, acrylic acid, methylolated acrylamide,
Glycidyl acrylate or glycidyl methacrylate or grafted products of macromers thereof are particularly preferred.

After coating, the polyester copolymer having these reactive groups can be crosslinked by heating, etc., but it is more preferable to use a crosslinking catalyst in combination because the crosslinking will proceed further. As the crosslinking catalyst, ammonium chloride, ammonium nitrate, citric acid, oxalic acid, p-toluenesulfonic acid, dialkyl tin compounds, etc. can be used. The amount of crosslinking catalyst added is 0.5 to 5 parts, preferably 1 to 3 parts, based on the solid content of the polyester copolymer.

After applying the polyester copolymer containing a crosslinking agent and the polyester copolymer containing a reactive group to the substrate, heating and
Common methods include crosslinking with ultraviolet rays, electron beams, etc., or heating.

Heating is not particularly limited as long as the strip 1 is crosslinked to the extent that the purpose of the present invention can be achieved, but is usually 60 to 260°C.
The temperature is 0.1 seconds to 15 minutes, preferably 1 second to 2 minutes at 100 to 240'C. When the base film is a biaxially stretched polyester film, it is more preferable to perform drying and heat treatment after coating during the manufacturing process because crosslinking at high temperatures is possible.

The average particle diameter (D>) of the inorganic particles (a) used in the present invention is
0.08 to 2.2 μm, preferably 0.08 to 0
．． It is 6 μm. When the average particle diameter (D) is less than 0.08 μm, the blocking resistance of the film becomes insufficient,
Furthermore, since the agglomeration of the particles increases, the generation of coarse foreign matter deteriorates electrical insulation, which is not preferable. on the other hand,
If it exceeds 2.2 μm, the surface of the film will become noticeably rough and the electrical insulation properties will similarly deteriorate, which is not preferable.

In addition, the average particle diameter here is measured using a centrifugal sedimentation type particle size distribution analyzer (Model 5A-CP2 manufactured by Shimadzu Corporation).

The type of inorganic particles (a) used in the present invention is not particularly limited, but representative particles include talc, kaolin, heavy, light or synthetic calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride. , barium sulfate, alumina, zirconia, calcium phosphate or natural or synthetic swellable or non-swellable mica. However, from the viewpoint of dispersibility in paints, it is preferable to use inorganic colloids that exist in colloidal form in water.

The inorganic colloid mentioned here is defined in the Chemistry Dictionary published by Coexistence Publishing Co., Ltd., and there are 105 to 100 colloids in one particle.
It contains nine atoms. Depending on the element, it can be obtained as a metal colloid, oxide colloid, or hydroxide colloid. Preferably used metal colloids include gold, palladium, platinum, silver, and sulfur; examples of oxide colloids, hydroxide colloids, carbonate colloids, and sulfate colloids include zinc, magnesium, silicon, calcium, aluminum, and strontium. , barium, zirconium, titanium, manganese, iron, ]balt, nickel, tin, etc., oxide colloids, hydroxide colloids, carbonate colloids, and sulfate colloids are preferably used in the present invention. For example, adding silicon tetrahalide to water,
A silicate colloid obtained by gradually adding concentrated hydrochloric acid to an aqueous solution of an alkali silicate is very preferably used in the present invention.

The average particle size of the inorganic colloid is 0.08-0.6 μm, preferably 0.11-0.3 μm, more preferably 0.15
A range of 0.25 μm is desirable. This is preferable when the average particle diameter is 0.08 to 0.6 μm because the stability of the inorganic colloid particles in an aqueous solution is excellent.

The film of the present invention has an average particle diameter (D
) and the coating layer thickness (d) (D/d) is 1.1 to 80
Must. Preferably it is in the range of 2.0-40, more preferably 3.0-15. (D/d) is 1.
(0) Yellow is not preferred because it deteriorates the slipperiness and anti-blocking properties of the laminated film. On the other hand, (D/d) is 8
If it is 0 or more, the abrasion resistance of the easy-adhesive layer deteriorates, and powder is generated, resulting in product defects, which is not preferable.

Next, a typical method for manufacturing the film of the present invention will be described, but the method is not limited thereto.

First, a biaxially stretched polyester film to be used as a base material is prepared. This film may be subjected to corona discharge treatment in air or other various atmospheres, if necessary. Anchor treatment may be performed using a known anchor treatment agent such as urethane resin or epoxy resin, but this is usually not necessary. The coating layer is coated on the film using a known method such as gravure coating, reverse coating, or spray coating, and then heated at 60'C to 260C at 0.
．． Let dry for about 1 second to 15 minutes.

Alternatively, the N layer may be formed separately and laminated with a film, but since the strength of the coating layer is somewhat insufficient, it is preferable to directly coat the base film.

It is also possible to apply it during the manufacturing process of the base film. That is, to give a specific example, the polyester film is coated on at least one side of the polyester film after being stretched in one direction, and after drying, or after being stretched in the right angle direction while drying, heat treatment is performed; After stretching,
This is a method of re-stretching in one direction and performing heat treatment. This method is particularly preferred because it allows the coating layer to be applied thinly and uniformly, and because crosslinking of the polyester copolymer progresses rapidly and to a high degree.

Note that the characteristic values used in the present invention are based on the following measurement method and evaluation criteria.

(1) Anti-blocking film with a predetermined coating layer on both sides, thickness 110C1,
Stack 50 sheets of A4 size film and set the ambient temperature to 17.
Leave in a hot air oven at 0'C for 60 minutes. The samples are slowly cooled at room temperature and then peeled off one by one. At that time, the materials that can be peeled off like before heat treatment without sticking to each other are
○”, and the others are determined as IXj.

(2) Room-temperature adhesion After applying each of the following four types of paints i) to -17=■) on the prescribed coating layer and curing, make a so-called goban of 1 mm square, and tape the area with cellophane tape. Chiban (41)
Forced peeling was performed in a 180° direction with a 180° direction (manufactured by Manufacturer Co., Ltd.), and the result was rated as 1 based on the following criteria. In other words, "○" means that less than 15% of the total peeled area is peeled off, and "×" means that more than 15% of the total peeled area peels off.
And so. Moreover, when the peeled area was less than 5%, it was judged as "◎". However, Table 1 shows the results for the case where the adhesion was the worst among the four types of paint.

i> Nippon Acheson ED450SS (50%) M
After applying L-25089 (50%) to a 7 μm cloth using the screen printing method, a UV irradiation device (80 W/cm x 3 lights, height 150 mm)
8 m/min processing).

ii) DuPont's "Virox" 1400 6μm
After coating, it was heat cured.

100 parts of Seiko Advance Co., Ltd. 0VA-9119, 5 VX-12040 parts was applied to a thickness of 4 μm, and then cured in the same manner as in i).

iv) Toyo Ink FD-33(i) 100
After applying 5 parts of FD Reducer P to a thickness of 4 μm, it was cured in the same manner as in i).

(3) The above-mentioned four types of paints i) to i1/) were applied on the moisture-resistant adhesion coating layer, and the cured film was left at 85°C and 195%RH for 4 days, and then the same coating layer as in (2) was applied. The evaluation was made and the judgment was made.

(4) The surface of the coating layer of the abrasion-resistant tape-shaped film is made of metal (SUS)
After repeatedly running in contact with a fixed guide (5 mmφ) 100 times, the amount of scratches attached to the film was observed.
Judgments were made based on the number as follows.

○ Few varnish scratches (good durability), many X varnish scratches (poor durability) (5) Thickness of the coating layer d (μm) Apply cellophane tape to the coating layer, and tape the coating layer at the end of the cellophane chip. Dissolve and remove with a solvent such as formamide. Next, the cellophane tape was peeled off, and the boundary between the surface protected by the cellophane tape and the surface that had been dissolved and removed was measured using a F-10 high-precision step measuring device manufactured by Koita Research Institute, and the thickness was determined.

If the above method was difficult, an ultra-thin section of the laminated film was observed using a transmission electron microscope 1" U-12 model manufactured by Hitachi, Ltd., and the thickness was determined.

(6) Center line average roughness According to Jl5-B-0601, using a stylus type surface roughness meter 5D-3 manufactured by Koita Research Institute, cutoff 0.25 m.
The average roughness Ra (μm) was measured at a measurement length of 1 mm.

(7) Dielectric breakdown characteristics Nippon Acheson's "electrodag 450SS"
was applied to a film thickness of 25μm, and UV clamped at 20W/cmx.
After curing with irradiation at 6 m/min (height 150 mm) with 2 lamps, the dielectric breakdown voltage of 2000 V-Ac/mouth was measured with n-50 based on ASTM D-149A, and the variation excluding the maximum and minimum values was When it exceeds 40% of the average breakdown voltage, it is marked as rXJ, and when it is smaller than that, it is marked as "○".

〔Example〕

The present invention will be explained using the following examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 6, Comparative Examples 1 to 6 Silicon oxide with an average particle size of 0.15 μm was added to polyethylene terephthalate with an intrinsic viscosity of 0964 at 8% (Comparative Example 1) and 0.018% (Examples 1.4 to 6, Comparative). Examples 3-6
), 6.035% (Example 2>, 0.06% (Example 3)
), 0.14% (Comparative Example 2) added, and the resin was heated at 285°C.
The mixture was melted at 50°C and extruded onto a cooling drum with a surface temperature of 50°C. The film thus obtained was heated in the longitudinal direction at 900C for 3
．． After stretching 8 times, the surface was subjected to corona discharge treatment, and then a paint having the composition shown below was applied by gravure coating using water as a solvent. Thereafter, while drying the paint, it was stretched 3.3 times in the transverse direction at 100 DEG C., and further heat-treated in an atmosphere of 220 DEG C. while relaxing it in the transverse direction by 4%.

The composition of the paint used is as follows.

A, methacrylic acid and glycidyl acrylate-1 to 20 each
Water-dispersible polyester copolymer grafted in the form of mol% macromer.Product name: Takamatsu Yushi ■Pess Resin 6
04G>100 parts by weight B, melamine crosslinking agent (trade name Konicalak MWIOL
F) 8 parts by weight C, silica sol (however, the average particle size is shown in Table 1) 2.
Various physical properties of the film obtained in an amount of 5 parts by weight were evaluated.

The results are shown in Table 1.

As shown in Table 1, it can be seen that good characteristics are exhibited only when the properties are within the range of the present invention. Moreover, especially in the case of Example 2, blocking resistance and dielectric breakdown properties were particularly good.

Example 6 A film was formed using the same method as in Example 2. However, the paint was applied not to a uniaxially stretched film but to a heat-treated biaxially stretched film using a gravure coating method and dried at 150°C. The film thus obtained was similarly evaluated. Although the adhesion was slightly inferior to that of Example 2, it showed similarly good characteristics.

〔Effect of the invention〕

In the present invention, since a predetermined coating layer is provided on a biaxially stretched polyester film having a specific center line average roughness, it exhibits the following excellent effects and is suitable for use as a wiring board.

(1) Excellent adhesion with various inks and polymer pastes.

(2) Its adhesion hardly changes even under high temperature and high humidity atmosphere.

(3) Excellent blocking resistance.

Claims (3)

[Claims] (1) At least one side of a biaxially stretched polyester film having a center line average roughness of 0.02 to 0.50 μm is coated with inorganic particles (a) having an average particle size of 0.08 to 2.2 μm and a crosslinked polyester film. It consists of a component whose main component is a polymer (b), and the ratio (D/d) of the average particle diameter (D) of the inorganic particles (a) to the layer thickness (d) is in the range of 1.1 to 80. A polyester film for wiring boards, characterized by being provided with a coating layer. (2) The polyester film for a wiring board according to claim 1, wherein the coating layer is stretched. (3) The polyester film for a wiring board according to claim 1, characterized in that the polyester copolymer is grafted with a crosslinkable acrylic acid or methacrylic acid compound.