JPH1171551A - Resin composition for flexible circuit overcoating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin composition having such performance as to sufficiently satisfy various properties including flexibility, low shrinkage when cured, adhesivity, electrical insulation, chemical resistance and heat resistance. SOLUTION: This thermosetting resin composition comprises (A) a polybutadiene polyol 1,000-8,000 in number-average molecular weight, bearing 2-10 hydroxyl groups per molecule, (B) a polyester polyol 13,000-30,000 in number-average molecular weight, bearing 2-10 hydroxyl groups per molecule, and (C) a polybutadiene polyblocked isocyanate 1,000-8,000 in number-average molecular weight, bearing 2-10 hydroxyl groups per molecule, in a weight ratio A/B of (40:60) to (90:10); wherein the amount of the component C is such as to be 0.8-3.5 equivalent based on the total hydroxyl group equivalent of the polyols.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin composition for a flexible circuit overcoat which is particularly excellent in flexibility and low shrinkage during curing.

[0002]

2. Description of the Related Art Conventionally, a surface protective film of a flexible wiring circuit has a type in which a polyimide film called a coverlay film is formed by punching a mold in conformity with a pattern and then punched using an adhesive, or has a flexibility. A UV-curable or thermosetting overcoating agent is applied by screen printing, and the latter is particularly useful in terms of workability. As these curable overcoat agents, resin compositions mainly composed of an epoxy resin, an acrylic resin, or a composite thereof are known. In many cases, these resins are mainly composed of a modified resin such as a butadiene skeleton, a siloxane skeleton, or a long-chain aliphatic skeleton, and thus have inherent heat resistance, chemical resistance, and electrical insulation properties. While suppressing the decrease as much as possible, improvement in flexibility and suppression of warpage due to curing shrinkage have been performed. However, in recent years, as the weight and size of electronic devices have been reduced, the weight of flexible substrates has also been reduced, and with this, the influence of the flexibility and curing shrinkage of the resin composition to be overcoated has become more noticeable. . For this reason, curable overcoat agents cannot satisfy the required performance in terms of flexibility and warpage due to curing shrinkage at present.

[0003]

In these respects, flexibility, low shrinkage upon curing, adhesion, electrical insulation, chemical resistance, heat resistance, etc., which are required as characteristics of the overcoat agent for flexible circuits. At present, a resin composition having a performance sufficiently satisfying the above-mentioned characteristics has not been found.

[0004]

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that polybutadiene polyol having a number average molecular weight of 1,000 to 8,000 and having 2 to 10 hydroxyl groups per molecule, Number average molecular weight is 1
A polyester polyol having 3000 to 30,000 and 2 to 10 hydroxyl groups per molecule and a polybutadiene polyblock isocyanate having a number average molecular weight of 1000 to 8000 and 2 to 10 hydroxyl groups per molecule are mixed at a predetermined ratio. By doing so, it was found that a resin composition having performance that can sufficiently satisfy various properties such as flexibility, low shrinkage during curing, adhesion, electrical insulation, chemical resistance, and heat resistance can be obtained. Completed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION That is, the present invention comprises
(A) a polybutadiene polyol having a number average molecular weight of 1,000 to 8,000 and having 2 to 10 hydroxyl groups per molecule, (B) a number average molecular weight of 13,000 to 30,000
And a polyester polyol having 2 to 10 hydroxyl groups per molecule and (C) a number average molecular weight of 1000 to 8
000, polybutadiene polyblock isocyanate having 2 to 10 hydroxyl groups per molecule as an essential component, and the weight ratio of the polyol is (A):
(B) = 40: 60 to 90:10, wherein the amount of the polyblocked isocyanate (C) is 0.8 to 3.5 equivalents to the total hydroxyl equivalents of the polyol. is there. Hereinafter, the present invention will be described in detail.

The number average molecular weight of component (A) is 10
A polybutadiene polyol having a hydroxyl number of 2 to 10 per molecule, having a molecular weight of from 8000 to 8000, has properties such as heat resistance and chemical resistance found in rigid resins, and properties found in flexible resins such as flexibility and low shrinkage. It is important to give both. If the molecular weight is smaller than this range,
If the number of hydroxyl groups per molecule is larger than this range, the crosslink density at the time of curing will be high, resulting in a harder cured product, and sufficient physical properties regarding the flexibility of the cured coating film and low shrinkage during curing. Cannot be obtained. On the other hand, when the molecular weight is larger than this range, or when the number of hydroxyl groups per molecule is smaller than this range, the crosslink density at the time of curing becomes low, so that a more flexible cured product is obtained. The heat resistance and chemical resistance of the coating film are significantly reduced. Further, since the component (A) has a polybutadiene skeleton, there is an effect of further improving flexibility and low shrinkage during curing.

The number average molecular weight of component (B) is 1300
A polyester polyol having 0 to 30,000 and having 2 to 10 hydroxyl groups per molecule imparts properties such as improved flexibility and low shrinkage during curing, which are found in flexible cured products, and the polarity contained in the resin skeleton. It is important to improve the adhesion to the substrate due to the effect of the high ester bond.

The number average molecular weight of the component (C) is 1000
Polybutadiene polyblock isocyanate having from 2 to 10 blocked isocyanate groups per molecule at 8000 is used for rigid resin such as heat resistance and chemical resistance, and for flexible resin such as flexibility and low shrinkage. It is important to give both of the properties seen. When the molecular weight is smaller than this range, or when the number of hydroxyl groups per molecule is larger than this range, the crosslink density at the time of curing increases, resulting in a harder cured product and the flexibility of the cured coating film. Sufficient physical properties cannot be obtained with regard to low shrinkage during curing and curing. On the other hand, when the molecular weight is larger than this range, or when the number of hydroxyl groups per molecule is smaller than this range, the crosslink density at the time of curing becomes low, so that a more flexible cured product is obtained. The heat resistance and chemical resistance of the coating film are significantly reduced. Further, since the component (A) has a polybutadiene skeleton, there is an effect of further improving flexibility and low shrinkage during curing.

When only polybutadiene polyol (A) alone is cured with polybutadiene polyisocyanate (B), a cured product having a good balance of heat resistance, chemical resistance and flexibility, and low shrinkage during curing is obtained. Nevertheless, the properties are not completely satisfactory with respect to flexibility, low shrinkage during curing, and adhesion to the substrate, and therefore, it is necessary to combine with polyester polyol (B). That is, (A) :( B) = 4
It is preferable to use a mixture in the range of 0:60 to 90:10. When the amount of the polyol (A) is less than this range, the crosslinking density is too low, and the properties such as heat resistance and chemical resistance of the coating film. Is significantly reduced. Further, the amount of the polybutadiene polyblock isocyanate (C) is preferably 0.8 to 3.5 equivalents to the total hydroxyl equivalents of the polyol. Too much, the properties of the coating such as heat resistance and chemical resistance are remarkably reduced.

The polybutadiene polyol (A) may have any number as long as it has a number average molecular weight of 1,000 to 8,000, has 2 to 10 hydroxyl groups per molecule, and has a butadiene skeleton. For example,
G-1000, GI-1000, GQ-1000, (all manufactured by Nippon Soda Co., Ltd.), R-45EPI (Idemitsu Petrochemical Co., Ltd.) and the like.

[0011] As the polyester polyol (B),
Any number may be used as long as the number average molecular weight is 13,000 to 30,000, the number of hydroxyl groups is 2 to 10 per molecule, and the polyester has a polyester skeleton. For example, Byron-200, Byron-103, Byron- 60
0 (all manufactured by Toyobo Co., Ltd.), Elitel UE34
00, UE3500, UE3600 (all manufactured by Unitika Ltd.), Aronmelt PES310-S30, P
ES340-S30, PES390-S30 (manufactured by Toagosei Chemical Industry Co., Ltd.) and the like.

The polybutadiene polyblock isocyanate (C) is obtained by blocking an isocyanate group-containing polybutadiene polyisocyanate with a blocking agent. Examples of the polybutadiene polyisocyanate include toluene-2,4-diisocyanate,
Diisocyanates such as toluene-2,6-diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate; Is reacted with various polyols to make it trifunctional or higher, and reacted with a polybutadiene having a number average molecular weight of 600 to 7000 hydroxyl group. For example, TP-1002 (manufactured by Nippon Soda Co., Ltd.) And HTP-9, HTP-5 MLD, and Unimax P (all manufactured by Idemitsu Petrochemical Co., Ltd.). Further, as the blocking agent, a compound having only one active hydrogen capable of reacting with an isocyanate group in one molecule and dissociating again at a temperature of 170 ° C. or less even after reacting with the isocyanate group is preferable, and ε-caprolactam, Examples include diethyl malonate, ethyl acetoacetate, acetoxime, methyl ethyl ketoxime, phenol, cresol and the like.

In the present invention, in addition to the above essential components, a curing accelerator for polyol and isocyanate, a filler, an additive, a thixotropic agent, a solvent and the like may be added as necessary. In particular, it is preferable to add rubber fine particles in order to further improve the bending resistance, and also to improve the adhesion with the underlying copper circuit, the base material such as polyimide and polyester film, and the adhesive layer. Therefore, it is preferable to add polyamide fine particles.

The fine rubber particles are fine particles of a resin which is obtained by subjecting a resin exhibiting rubber elasticity such as acrylonitrile-butadiene rubber, butadiene rubber, acrylic rubber or the like to a chemical crosslinking treatment so as to be insoluble and insoluble in an organic solvent. Any material may be used, for example, XER-91 (manufactured by Nippon Synthetic Rubber Co., Ltd.), Staphyloid AC3355,
AC3832, IM101 (above, Takeda Pharmaceutical Co., Ltd.)
And paraloids EXL2655 and EXL2602 (all manufactured by Kureha Chemical Industry Co., Ltd.).

As the polyamide fine particles, any fine particles of a resin having an amide bond, such as an aliphatic polyamide such as nylon or an aromatic polyamide such as Kevlar, and polyamide imide having a size of 50 μm or less can be used. For example, VESTOSINT 2070 (manufactured by Daicel Huls Co., Ltd.), SP500 (manufactured by Toray Industries, Inc.) and the like can be mentioned.

[0016]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to production examples of polyols and blocked isocyanates used in the present invention and examples of the present invention, together with comparative examples.

[0017]

[Production example]

<Production of resin varnish E> Byron-200 was added to the reaction vessel.
(OH-terminated polyester, Mn = about 15000, OH equivalent = 7014 g / eq., Solid content 100 w%: manufactured by Toyobo Co., Ltd.) 2250 g, ethyl diglycol acetate (manufactured by Daicel Chemical Industries, Ltd.) 1833 g, 917 g of Ipsol 150 (manufactured by Idemitsu Petrochemical Co., Ltd.) was added, stirred while heating to 130 ° C., and dissolved to obtain a resin varnish E. Properties of resin varnish E: Mn = about 15000, OH equivalent (including solvent) = 15586 g / eq. , Solid content = 45w%

<Production of Resin Varnish F>
000 (OH-terminated polybutadiene, Mn = about 1600,
OH equivalent = 801 g / eq. , Solid content = 100 w%: manufactured by Nippon Soda Co., Ltd.)
591 g (manufactured by Idemitsu Petrochemical Co., Ltd.) and 0.1 g of dibutyltin laurate are mixed and uniformly dissolved. When the mixture became homogeneous, the temperature was raised to 70 ° C., and while stirring, toluene-2,4-diisocyanate (NCO equivalent = 87.0).
8 g / eq. ) 97.8 g was added dropwise over 2 hours, and the mixture was kept for 1 hour, and NCO of 2250 cm -1 was measured by FT-IR.
When the disappearance of the peak was confirmed, the temperature was lowered to obtain a resin varnish F. Properties of resin varnish F: Mn = about 17000, OH equivalent (including solvent) = 13532 g / eq. , Solid content = 65w%

<Production of Resin Varnish G>
-9 (NCO-terminated polybutadiene, NCO equivalent = 467
g / eq. , Solid content = 100w%: Idemitsu Petrochemical Co., Ltd.
1000 g), 216 g of ethyl diglycol acetate (manufactured by Daicel Chemical Industries, Ltd.) and 0.1 g of dibutyltin laurate are mixed and uniformly dissolved. When it became uniform, the temperature was raised to 70 ° C, and with further stirring,
Methyl ethyl ketoxime (molecular weight 87.12) 224
g was added dropwise over 2 hours and kept for 1 hour, FT-IR
When the disappearance of the NCO peak at 2250 cm -1 was confirmed, the temperature was lowered to obtain a resin varnish G. Properties of resin varnish G: NCO equivalent = 672.5 g / e
q. , Solid content = 85w%

<Evaluation method of coating film> Warpage due to curing shrinkage: 35 mm × 60 mm × 75 μ
25mm × 35mm × 25 on polyimide film
Apply in μm and measure the amount of warpage after curing. Bending resistance test: Mandrel test. Perform a bending test in the range of 1１〜 inch diameter. → The display shows the minimum diameter at which cracks do not occur. Pencil hardness: according to JIS D0202. Electrical insulation: applied to a comb-shaped electrode with a conductor width of 0.318 mm, and measured for electrical resistance one hour after boiling. Chemical resistance: Rubbing the coating film with a cloth impregnated with acetone or isopropanol. → ○: No abnormality
×: Deterioration of coating film Solder heat resistance: Flux JS-64MS-S applied to coating film
And dipped in a 260 ° C. solder bath for 10 seconds.
→ ：: No abnormality, swelling occurred Bending resistance: Performed according to JIS C5016.
The radius of the bent surface was 0.38 mm, and the number of bendings before cracking was measured. → ×: 10 times or less, Δ: 10 to 1000 times, ○: 100
0 to 2000 times, ◎: 2000 times or more Adhesion: According to JIS D0202. As a base material,
The test was performed on copper, polyimide, and an adhesive layer of a flexible substrate. → ×: 0/100 to 50/100, Δ: 51/100 to
99/100, ○: 100/100

[0021]

Examples 1 to 4 <Preparation of Curable Resin Composition> (A) Component: Polybutadiene polyol G-1000 (OH-terminated polybutadiene, Mn = about 1)
500, OH equivalent = 801 g / eq. , Solid content = 100
w%: manufactured by Nippon Soda Co., Ltd.) (B) Component: Polyester polyol Resin varnish E (OH-terminated polyester, Mn = about 17)
000, OH equivalent (including solvent) = 15586 g / eq. ,
(Solid content = 45 w%) Polyol other than the components (A) and (B) Desmophen A665 (acryl polyol, Mn =
About 1000, OH equivalent (including solvent) = 607 g / eq. ,
Solid content = 65% by weight: manufactured by Sumitomo Bayer Urethane Co., Ltd.) Resin varnish F (OH-terminated polybutadiene, Mn = about 1)
7000, OH equivalent (including solvent) = 13532 g / eq.
(Solid content: 65 w%) (C) component: polybutadiene polyblock isocyanate ・ Resin varnish G (NCO terminal polybutadiene, NCO equivalent = 672.5 g / eq., Solid content = 85 w%) Polyblock isocyanate other than component (C) ・ LS4265 (Oxime block of isophorone diisocyanate trimer, NCO equivalent (including solvent) = 519 g
/ Eq. , Solid content = 65w%: manufactured by Sumitomo Bayer Urethane Co., Ltd.)

The above polyol and polyblock isocyanate are blended according to Table 1, and as other components,
Dibutyltin laurate as a curing accelerator, Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) as an anti-sagging agent,
Carbitol acetate as a viscosity adjusting solvent was added and mixed in an appropriate amount for each formulation, kneaded using a three-roll mill,
Samples A1 to A4 shown in Table 1 were prepared. Samples A1 to
A4 is applied to an arbitrary substrate to a thickness of about 25 μm,
Curing was performed for 60 minutes to prepare a test sample.
Table 2 shows the measurement results. Thus, the coating film of the curable resin composition of the present invention has a particularly small amount of warpage, flexibility, and excellent chemical resistance, heat resistance, electrical insulation, and adhesion, and each property is well balanced. I have. In addition, the numerical value in a table | surface represents the weight part containing the solvent component in a raw material.

[0023]

[Table 1]

[0024]

Comparative Examples 1 to 3 Samples B1 to B3 were prepared and evaluated according to the formulations shown in Table 1 in accordance with the examples. The results are shown in Table 2.

[0025]

[Table 2]

[0026]

As shown in the Examples, the resin composition of the present invention is particularly excellent in flexibility, warpage during curing, and excellent in chemical resistance, heat resistance, electrical insulation, and adhesion. It is a curable resin composition and is suitable as an overcoat agent for a flexible circuit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 75/04 C08L 75/04 H05K 3/28 H05K 3/28 F

Claims (2)

[Claims] 1. A component (A) a polybutadiene polyol having a number average molecular weight of 1,000 to 8,000 and having 2 to 10 hydroxyl groups per molecule, and (B) a number average molecular weight of 13,000 to 30,000.
And a polyester polyol having 2 to 10 hydroxyl groups per molecule and (C) a number average molecular weight of 1,000 to 8
000, polybutadiene polyblock isocyanate having 2 to 10 blocked isocyanate groups per molecule as an essential component, and the weight ratio of the polyol is (A) :( B) = 40: 60 to 90:10 as solid content. ,
A resin composition for a flexible circuit overcoat, wherein the amount of the polyblock isocyanate is 0.8 to 3.5 equivalents to the total hydroxyl equivalents of the polyol. 2. The resin composition for overcoating a flexible circuit according to claim 1, which comprises rubber fine particles and / or polyamide fine particles.