ADHESIVE COMPOSITION, AND ADHESIVE LAYER-EQUIPPED LAYERED PRODUCT USING SAME

Abstract

Provided is an adhesive composition that is characterized by containing a modified polypropylene-based resin (A), an epoxy resin (B) and an unmodified polypropylene-based resin (C), with the modified polypropylene-based resin (A) being a resin obtained by graft modifying an unmodified polypropylene-based resin (D) with a modifying agent that contains an ,-unsaturated carboxylic acid or a derivative thereof, the content of the modified polypropylene-based resin (A) being 10 mass % or more in terms of solid content, and the content of the unmodified polypropylene-based resin (C) being 1-90 mass % in terms of solid content. The adhesive composition exhibits good adhesion to a copper foil or a base material film comprising a polyimide resin or the like, and exhibits improved dielectric properties.

Claims

1. An adhesive composition, which comprises a modified polypropylene-based resin (A), an epoxy resin (B), and an unmodified polypropylene-based resin (C), in which the modified polypropylene-based resin (A) is a resin resulting from graft-modification of an unmodified polypropylene-based resin (D) with a modifying agent comprising an ,-unsaturated carboxylic acid or derivative thereof, and which has a content of the modified polypropylene-based resin (A) of 10 parts by mass or more relative to 100 parts by mass of solid content of the adhesive composition, and which has a content of the unmodified polypropylene-based resin (C) of 1 part by mass or more and 90 parts by mass or less relative to 100 parts by mass of solid content of the adhesive composition.

2. The adhesive composition according to claim 1, wherein the derivative of the ,-unsaturated carboxylic acid is at least one selected from the group consisting of itaconic anhydride, maleic anhydride, aconitic anhydride, and citraconic anhydride.

3. The adhesive composition according to claim 1, wherein the grafted portions derived from the ,-unsaturated carboxylic acid or derivative thereof are contained in a percentage of from 0.1 to 20 mass % relative to 100 mass % of the modified polypropylene-based resin (A).

4. The adhesive composition according to claim 1, wherein the epoxy resin (B) is a multifunctional epoxy resin having an alicyclic structure.

5. The adhesive composition according to claim 1, wherein the modified polypropylene-based resin (A) has a propylene copolymerization ratio of 70 mass % or less.

6. The adhesive composition according to claim 1, wherein the unmodified polypropylene-based resin (C) has a propylene copolymerization ratio of 70 mass % or less.

7. The adhesive composition according to claim 1, wherein the unmodified polypropylene-based resin (C) and the unmodified polypropylene-based resin (D) are each at least one selected from the group consisting of ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers.

8. The adhesive composition according to claim 1, wherein the adhesive composition further comprises an antioxidant.

9. The adhesive composition according to claim 1, wherein the adhesive composition further comprises an organic solvent, wherein the modified polypropylene-based resin (A), the epoxy resin (B), and the unmodified polypropylene-based resin (C) are dissolved in the organic solvent.

10. The adhesive composition according to claim 9, wherein the organic solvent comprises an alicyclic hydrocarbon solvent that is methylcyclohexane and/or cyclohexane, and an alcohol-based solvent, which has a content of the alicyclic hydrocarbon of 20 parts by mass or more and 90 parts by mass or less relative to 100 parts by mass of the organic solvent, and which has a content of the alcohol-based solvent of 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the organic solvent.

11. The adhesive composition according to claim 9, wherein the organic solvent comprises toluene.

12. The adhesive composition according to claim 9, which has a solid content of 5 mass % or more and 50 mass % or less.

13. A laminate having an adhesive layer, which laminate comprises an adhesive layer formed of the adhesive composition according to claim 1, and a base film contacting at least one of the surfaces of the adhesive layer, wherein the adhesive layer is in B stage.

14. The laminate having an adhesive layer, according to claim 13, wherein the base film is at least one selected from the group consisting of a polyimide film, a polyether ether ketone film, a polyphenylene sulfide film, an aramid film, a polyethylene naphthalate film, a liquid crystal polymer film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a silicone-treated release paper, a polyolefin resin coated paper, a TPX film, a fluorine-based resin film, and a copper foil.

15. A printed wiring board which comprises an adhesive layer formed of the adhesive composition according to claim 1.

16. A flexible flat cable which comprises an adhesive layer formed of the adhesive composition according to claim 1.

Description

EXAMPLES

[0129] The present invention is explained in further detail by way of Examples below, but the present invention is not limited thereto. In the explanation below, parts and % are on mass basis unless otherwise stated.

1. Evaluation Method

(1) Weight Average Molecular Weight

[0130] GPC measurement was carried out under the following conditions to determine Mw of the modified polypropylene-based resin (A).

[0131] Mw was determined by converting the retention time measured by GPC based on standard polystyrene retention time.

[0132] Instrument: Alliance2695 (manufactured by Waters)

[0133] Column: 2 columns of TSK gel SuperMultiporeHZ-H [0134] 2 columns of TSK gel SuperHZ2500 (manufactured by Tosoh Corporation)

[0135] Column temperature: 40 C.

[0136] Carrier solvent: Tetrahydrofuran 0.35 ml/min

[0137] Detector: RI (Differential Refractive Index Detector)

(2) Acid Value

[0138] One (1) gram of the modified polypropylene-based resin (A) was dissolved in 30 ml of toluene, and an automatic titrator AT-510 (manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD.) to which a burette APB-510-20B (manufactured by the same) was connected was used. Potentiometric titration was carried out using 0.01 mol/L benzyl alcoholic KOH solution as a titrant, and an amount in milligrams of KOH per 1 g of resin was calculated.

(3) Peel Adhesion Strength

[0139] A 25-m thick polyimide film was prepared, and the adhesive compositions of Examples 1 to 28 and of Comparative Examples 1 to 13 having compositions described in Table 1 were each applied by roll-coating to one of the surfaces of the film. The coated film was then allowed to stand still in an oven, and was dried at 90 C. for 3 minutes to form a 25-m thick adhesive layer in B stage to obtain a coverlay film (a laminate having the adhesive layer each of Examples 1 to 28 and Comparative Examples 1 to 13). Then, a 35-m thick rolled copper foil was brought into surface contact with the surface of the adhesive layer of the coverlay film, and the resultant was subjected to lamination under a temperature of 120 C., a pressure of 0.4 MPa, and a speed of 0.5 m/minute. Then, the resulting laminate (polyimide film/adhesive layer/copper foil) was subjected to hot pressing at a temperature of 180 C. and a pressure of 3 MPa for 30 minutes to obtain a flexible copper clad laminate A. The thus-obtained flexible copper clad laminate A was cut into a specified size to prepare an adhesion test piece.

[0140] In accordance with JIS C 6481 Test methods of copper-clad laminates for printed wiring boards, adhesiveness was evaluated by measuring a 180 peel adhesion strength (N/mm) when the copper foil of each adhesion test piece was peeled off from the polyimide film under a temperature of 23 C. and a tensile speed of 50 mm/minute. The width of the adhesion test piece at the time of measurement was 10 mm.

(4) Warpage

[0141] A 25-m thick polyimide film (200 mm length200 mm width) was prepared, and the adhesive compositions of Examples 1 to 28 and of Comparative Examples 1 to 13 having compositions described in Table 1 were each applied by roll-coating to one of the surfaces of the film. The coated film was then allowed to stand still in an oven, and was dried at 90 C. for 3 minutes to form a 25-m thick adhesive layer in B stage to obtain a coverlay film (a 50-m thick laminate having the adhesive layer each of Examples 1 to 28 and Comparative Examples 1 to 13). The resulting coverlay film was placed on a horizontal plane with the adhesive layer facing upward, and the elevation in the vertical direction was measured at each of the four corners. The thus-measured elevations at the four corners were averaged, and the ratio of the average elevation (H) to the side length (L) of the laminate, i.e., H/L, was obtained and used to evaluate the warpage.

<Evaluation Criteria>

[0142] : H/L is lower than 0.020

[0143] : H/L is 0.030 or more and lower than 0.05

[0144] : H/L is 0.10 or more

(5) Solder Heat Resistance

[0145] The test was conducted in accordance with JIS C 6481 Test methods of copper-clad laminates for printed wiring boards. The adhesion test pieces were each cut into 20-mm square, and were subjected to heat treatment at 120 C. for 30 minutes. Then, with the polyimide film facing up, the adhesion test pieces were floated on a solder bath for 60 seconds at 260 C. to observe foaming on the surface of the adhesion test pieces.

[0146] <Evaluation Criteria>

[0147] : Without blister

[0148] : With blister

(6) Dielectric Properties (Dielectric Constant and Dielectric Loss Tangent)

(a) Cured Body of the Adhesive

[0149] A 38-m thick polyethylene terephthalate release film was prepared, and one of the surfaces thereof was roll-coated with an adhesive composition each of Examples 1 to 28 and Comparative Examples 1 to 13 having compositions described in Table 1. The coated film was then allowed to stand still in an oven, and was dried at 90 C. for 3 minutes to form a 50-m thick coated film (adhesive layer) to obtain a bonding sheet. This bonding sheet was then allowed to stand still in an oven, and was treated with heat at 150 C. for 60 minutes or 180 C. for 30 minutes. Subsequently, the above release film was removed to prepare a test piece of 150 mm120 mm in size. The dielectric constant () and the dielectric loss tangent (tan ) were measured using a network analyzer 85071E-300 (manufactured by Agilent Technologies, Inc.) in accordance with the split post dielectric resonator (SPDR) method, at a temperature of 23 C. and at a frequency of 1 GHz.

(b) Laminate having Adhesive Layer

[0150] A 25-m thick polyimide film was prepared, and one of the surfaces thereof was roll-coated with an adhesive composition each of Examples 1 to 28 and Comparative Examples 1 to 13 having compositions described in Table 1. The coated film was then allowed to stand still in an oven, and was dried at 90 C. for 3 minutes to form a 25-m thick adhesive layer in B stage to obtain a coverlay film (a 50-m thick laminate having the adhesive layer each of Examples 1 to 28 and Comparative Examples 1 to 13). The resulting coverlay film was then allowed to stand still in an oven, and was heated and cured at 150 C. for 60 minutes to obtain a test piece of 120 mm100 mm in size.

[0151] The dielectric constant () and the dielectric loss tangent (tan ) of the laminate having an adhesive layer were measured using a network analyzer 85071E-300 (manufactured by Agilent Technologies, Inc.) in accordance with the split post dielectric resonator (SPDR) method, at a temperature of 23 C. and at a frequency of 1 GHz.

(7) Storage Stability of the Adhesive Composition

[0152] Each of the adhesive compositions of Examples 1 to 28 and Comparative Examples 1 to 13 having the compositions described in Table 1 was placed in a glass bottle, sealed, and stored at 5 C. for a predetermined time, and crystallinity of the compositions was observed. After storage for a predetermined time, the point where the fluidity of the adhesive composition disappeared was regarded as crystallization of the resin (poor storage stability), and evaluation was carried out.

<Evaluation Criteria>

[0153] : 1 month or more

[0154] : 2 weeks or more and less than 1 month

[0155] : 1 week or more and less than 2 weeks

[0156] : less than 1 week

(8) Storage Stability of the Laminate having an Adhesive Layer

[0157] A 25-m thick polyimide film was prepared, and one of the surfaces thereof was roll-coated with an adhesive composition each of Examples 1 to 28 and Comparative Examples 1 to 13 having compositions described in Table 1. The coated film was then allowed to stand still in an oven, and was dried at 90 C. for 3 minutes to form a 25-m thick adhesive layer in B stage to obtain a coverlay film (a 50-m thick laminate having the adhesive layer each of Examples 1 to 28 and Comparative Examples 1 to 13). The prepared coverlay film was stored at 23 C. for a predetermined duration of time, and the coverlay film after storage was subjected to hot pressing with a copper single-sided board (L/S=50 m/50 m, having copper thickness of 18 m) at a temperature of 180 C. and a pressure of 3 MPa for 3 minutes to evaluate a filling property of the resin. The storage period of time at which the resin no longer fills in the board was taken for evaluation.

<Evaluation Criteria>

[0158] : 2 months or longer

[0159] : 1 week or longer and less than 1 month

2. Production of Modified Polypropylene-Based Resin (A)

[0160] Modified polypropylene-based resins al to a3 were produced as the modified polypropylene-based resin (A) by the method described below.

(1) Modified Polypropylene-Based Resin a1

[0161] One hundred (100) parts by mass of a propylene-butene random copolymer composed of 65 mass % of propylene units and 35 mass % of 1-butene units and produced using a metallocene catalyst as a polymerization catalyst, 1 part by mass of maleic anhydride, 0.3 part by mass of lauryl methacrylate, and 0.4 part by mass of di-t-butylperoxide were kneaded and reacted in a twin-screw extruder in which the maximum temperature in the cylinder portion thereof was set to 170 C. Then, the remaining unreacted substances were removed by degassing in vacuo in the extruder to produce a modified polypropylene-based resin a1. The modified polypropylene-based resin al had a weight average molecular weight of 70,000, an acid value of 10 mg KOH/g, and a propylene/butene mass ratio of 65/35.

(2) Modified Polypropylene-Based Resin a2

[0162] One hundred (100) parts by mass of a propylene-butene random copolymer composed of 60 mass % of propylene units and 40 mass % of butene units and produced using a metallocene catalyst as a polymerization catalyst, 1 part by mass of maleic anhydride, 0.3 part by mass of lauryl methacrylate, and 0.4 part by mass of di-t-butylperoxide were kneaded and reacted in a twin-screw extruder in which the maximum temperature in the cylinder portion thereof was set to 170 C. Then, the remaining unreacted substances were removed by degassing in vacuo in the extruder to produce a modified polypropylene-based resin a2. The modified polypropylene-based resin a2 had a weight average molecular weight of 60,000, an acid value of 10 mg KOH/g, and a propylene/butene mass ratio of 60/40.

(3) Modified Polypropylene-Based Resin a3

[0163] One hundred (100) parts by mass of a propylene-butene random copolymer composed of 80 mass % of propylene units and 20 mass % of butene units and produced using a metallocene catalyst as a polymerization catalyst, 1 part by mass of maleic anhydride, 0.3 part by mass of lauryl methacrylate, and 0.4 part by mass of di-t-butylperoxide were kneaded and reacted in a twin-screw extruder in which the maximum temperature in the cylinder portion thereof was set to 170 C. Then, the remaining unreacted substances were removed by degassing in vacuo in the extruder to produce a modified polypropylene-based resin a3. The modified polypropylene-based resin a3 had a weight average molecular weight of 60,000, an acid value of 10 mg KOH/g, and a propylene/butene mass ratio of 80/20.

3. Production of Unmodified Polypropylene-Based Resin

(1) Unmodified Polypropylene-Based Resin c1

[0164] An unmodified polypropylene-based resin c1 was obtained, which was produced by reacting 65 mass % of propylene units and 35 mass % of butene units using a metallocene catalyst as a polymerization catalyst. The unmodified polypropylene-based resin cl had a weight average molecular weight of 150,000, and a propylene/butene mass ratio of 65/35.

(2) Unmodified Polypropylene-Based Resin c2

[0165] An unmodified polypropylene-based resin c2 was obtained, which was produced by reacting 60 mass % of propylene units and 40 mass % of butene units using a metallocene catalyst as a polymerization catalyst. The unmodified polypropylene-based resin c2 had a weight average molecular weight of 150,000, and a propylene/butene mass ratio of 60/40.

(3) Unmodified Polypropylene-Based Resin c3

[0166] An unmodified polypropylene-based resin c3 was obtained, which was produced by reacting 75 mass % of propylene units and 25 mass % of butene units using a metallocene catalyst as a polymerization catalyst. The unmodified polypropylene-based resin c3 had a weight average molecular weight of 150,000, and a propylene/butene mass ratio of 75/25.

4. Raw Materials of the Adhesive Composition

4-1. Epoxy Resin (B)

(1) Epoxy Resin b1

[0167] An epoxy resin having a dicyclopentadiene structure, EPICLON HP-7200 (trade name) manufactured by DIC Corporation, was used.

4-2. Additives

(1) Curing Accelerator

[0168] An imidazole-based curing accelerator CURESOL C11-Z (trade name), manufactured by Shikoku Chemicals Corporation was used.

(2) Antioxidant

[0169] A hindered phenol-based antioxidant AO-60 (trade name), manufactured by ADEKA Corporation was used.

4-3. Organic Solvent

[0170] Methylcyclohexane, cyclohexane, toluene, isopropyl alcohol, benzyl alcohol, and methyl ethyl ketone were used.

5. Production of an Adhesive Composition

[0171] The above raw materials were put into a 1000-ml flask equipped with a stirrer in the proportion shown in Table 1, and were dissolved under stirring for 6 hours at room temperature to prepare an adhesive composition, and evaluation thereof was carried out. The results are given in Table 1 and Table 2. The adhesive compositions of Comparative Examples 4, 5, and 13 were not subjected to the above evaluation, because resin components were not dissolved in the solvent.

6. Production and Evaluation of the Laminate having an Adhesive Layer

[0172] Laminates having adhesive layer were each produced using the above adhesive compositions as described above in explanation of each evaluation method, and were subjected to evaluation. The results are given in Table 1 and Table 2.

TABLE-US-00001 TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 Adhesive <Resin Acid-modified polypropylene-based 10 10 5 10 10 10 10 10 10 composition components> resin a1 (parts by mass) Acid-modified polypropylene-based 10 resin a2 Acid-modified polypropylene-based resin a3 Unmodified polypropylene-based 5 10 10 10 10 10 10 10 10 resin c1 Unmodified polypropylene-based 10 resin c2 Unmodified polypropylene-based resin c3 Epoxy resin b1 0.5 0.5 0.25 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Anti-thermal aging agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Curing accelerator 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 <Solvents> Methylcyclohexane 40 40 40 60 40 20 20 40 40 40 Cyclohexane 20 20 Toluene 40 40 40 20 20 60 40 40 40 40 Methyl ethyl ketone Isopropyl alcohol 5 5 5 5 5 5 5 5 5 Benzyl alcohol 5 <Evaluation Dielectric Dielectric constant () of cured body 2.17 2.15 2.13 2.15 2.15 2.15 2.15 2.15 2.16 2.16 results> properties of resin after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) of cured 0.0008 0.0007 0.0006 0.0007 0.0007 0.0007 0.0007 0.0007 0.0008 0.0008 body of resin after heat curing at 150 C. for 60 minutes Dielectric constant () of cured body 2.17 2.15 2.13 2.15 2.15 2.15 2.15 2.15 2.16 2.16 of resin after heat curing at 180 C. for 30 minutes Dielectric loss tangent (tan ) of cured 0.0008 0.0007 0.0006 0.0007 0.0007 0.0007 0.0007 0.0007 0.0008 0.0008 body of resin after heat curing at 180 C. for 30 minutes Dielectric constant () of coverlay 2.70 2.68 2.65 2.68 2.68 2.68 2.68 2.68 2.68 2.68 film after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) of 0.0030 0.0028 0.0027 0.0028 0.0028 0.0028 0.0028 0.0028 0.0030 0.0030 coverlay film after heat curing at 150 C. for 60 minutes Adhesiveness Peel adhesion strength of flexible 17 16 16 16 16 16 16 16 16 16 copper clad laminate (N/mm) Solder heat resistance of flexible copper clad laminate ( C.) Storage stability of adhesive composition at low temperatures Storage stability of coverlay film Warpage of coverlay film Examples 11 12 13 14 15 16 17 18 19 20 Adhesive <Resin Acid-modified polypropylene-based 10 10 10 10 10 3 composition components> resin a1 (parts by mass) Acid-modified polypropylene-based 10 10 resin a2 Acid-modified polypropylene-based 10 10 resin a3 Unmodified polypropylene-based 10 10 10 10 5 17 resin c1 Unmodified polypropylene-based 10 10 resin c2 Unmodified polypropylene-based 10 10 resin c3 Epoxy resin b1 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.15 Anti-thermal aging agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Curing accelerator 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 <Solvents> Methylcyclohexane 40 40 40 35 10 43 40 40 40 40 Cyclohexane Toluene 40 40 40 30 70 42 40 40 40 40 Methyl ethyl ketone 5 Isopropyl alcohol 5 5 20 5 5 5 5 5 Benzyl alcohol <Evaluation Dielectric Dielectric constant () of cured body 2.18 2.18 2.15 2.15 2.15 2.15 2.17 2.16 2.18 2.13 results> properties of resin after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) of cured 0.0008 0.0008 0.0007 0.0007 0.0007 0.0007 0.0008 0.0007 0.0007 0.0006 body of resin after heat curing at 150 C. for 60 minutes Dielectric constant () of cured body 2.18 2.28 2.15 2.15 2.15 2.15 2.17 2.16 2.18 2.13 of resin after heat curing at 180 C. for 30 minutes Dielectric loss tangent (tan ) of cured 0.0008 0.0030 0.0007 0.0007 0.0007 0.0007 0.0008 0.0007 0.0007 0.0006 body of resin after heat curing at 180 C. for 30 minutes Dielectric constant () of coverlay 2.70 2.70 2.68 2.68 2.68 2.68 2.70 2.68 2.70 2.63 film after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) of 0.0030 0.0030 0.0028 0.0028 0.0028 0.0028 0.0030 0.0028 0.0028 0.0027 coverlay film after heat curing at 150 C. for 60 minutes Adhesiveness Peel adhesion strength of flexible 16 16 16 16 16 16 16 16 16 15 copper clad laminate (N/mm) Solder heat resistance of flexible copper clad laminate ( C.) Storage stability of adhesive composition at low X X temperatures Storage stability of coverlay film Warpage of coverlay film

TABLE-US-00002 TABLE 2 Examples Comparative Examples 21 22 23 24 25 26 27 28 1 2 3 Adhesive <Resin Acid-modified 17 19 10 10 10 10 10 10 20 10 composition components> polypropylene-based resin a1 (parts by mass) Acid-modified polypropylene-based resin a2 Acid-modified polypropylene-based resin a3 Unmodified 3 1 5 5 5 5 5 5 20 10 polypropylene-based resin c1 Unmodified polypropylene-based resin c2 Unmodified polypropylene-based resin c3 Epoxy resin b1 0.85 0.95 0.5 0.5 0.5 0.5 0.5 0.5 1 1 Anti-thermal aging agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Curing accelerator 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.04 0.04 0.02 <Solvents> Methylcyclohexane 40 40 20 40 70 20 40 70 40 40 40 Cyclohexane Toluene 40 40 50 30 5 60 40 10 40 40 40 Methyl ethyl ketone Isopropyl alcohol 5 5 15 15 10 2 2 2 5 5 5 Benzyl alcohol <Evaluation Dielectric Dielectric constant () of 2.18 2.18 2.17 2.17 2.17 2.17 2.17 2.17 2.22 2.20 2.12 results> properties cured body of resin after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) 0.0009 0.0009 0.0008 0.0008 0.0008 0.0008 0.0008 0.0008 0.0012 0.0012 0.0006 of cured body of resin after heat curing at 150 C. for 60 minutes Dielectric constant () of 2.18 2.18 2.17 2.17 2.17 2.17 2.17 2.17 2.22 2.20 2.12 cured body of resin after heat curing at 180 C. for 30 minutes Dielectric loss tangent (tan ) 0.0009 0.0009 0.0008 0.0008 0.0008 0.0008 0.0008 0.0008 0.0012 0.0012 0.0006 of cured body of resin after heat curing at 180 C. for 30 minutes Dielectric constant () of 2.70 2.70 2.70 2.70 2.70 2.70 2.70 2.70 2.85 2.83 2.65 coverlay film after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) 0.0030 0.0030 0.0030 0.0030 0.003 0.003 0.003 0.003 0.0035 0.0035 0.0027 of coverlay film after heat curing at 150 C. for 60 minutes Adhesiveness Peel adhesion strength of 17 17 17 17 17 17 17 17 17 10 10 flexible copper clad laminate (N/mm) Solder heat resistance of flexible copper clad X X laminate ( C.) Storage stability of adhesive composition at low temperatures Storage stability of coverlay film Warpage of coverlay film Comparative Examples 4 5 6 7 8 9 10 11 12 13 Adhesive <Resin Acid-modified 1 1 20 20 20 20 20 20 composition components> polypropylene-based resin a1 (parts by mass) Acid-modified 20 polypropylene-based resin a2 Acid-modified polypropylene-based resin a3 Unmodified 19 17 0.1 polypropylene-based resin c1 Unmodified polypropylene-based resin c2 Unmodified 20 polypropylene-based resin c3 Epoxy resin b1 0.5 0.5 0.05 2.5 1 1 1 1 1 1 Anti-thermal aging agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Curing accelerator 0.02 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 <Solvents> Methylcyclohexane 85 80 40 40 40 5 15 15 5 80 Cyclohexane Toluene 40 40 40 75 65 45 55 Methyl ethyl ketone Isopropyl alcohol 5 5 5 5 5 5 25 25 5 Benzyl alcohol <Evaluation Dielectric Dielectric constant () of Not Not 2.12 2.27 2.22 2.22 2.22 2.22 2.22 Not results> properties cured body of resin after heat dissolved dissolved dissolved curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) 0.0006 0.0015 0.0012 0.0012 0.0012 0.0012 0.0012 of cured body of resin after heat curing at 150 C. for 60 minutes Dielectric constant () of 2.12 2.27 2.22 2.22 2.22 2.22 2.22 cured body of resin after heat curing at 180 C. for 30 minutes Dielectric loss tangent (tan ) 0.0006 0.0015 0.0012 0.0012 0.0012 0.0012 0.0012 of cured body of resin after heat curing at 180 C. for 30 minutes Dielectric constant () of 2.60 2.89 2.85 2.85 2.85 2.85 2.85 coverlay film after heat curing at 150 C. for 60 minutes Dielectric loss tangent (tan ) 0.0027 0.0038 0.0035 0.0035 0.0035 0.0035 0.0035 of coverlay film after heat curing at 150 C. for 60 minutes Adhesiveness Peel adhesion strength of 12 13 17 17 17 17 17 flexible copper clad laminate (N/mm) Solder heat resistance of flexible copper clad X laminate ( C.) Storage stability of adhesive composition at X X X low temperatures Storage stability of coverlay film Warpage of coverlay film

[0173] From the results in the above Table 1 and Table 2, the adhesive compositions of Examples 1 to 11 and 13 to 28 showed excellent dielectric properties in both cases of the heat-curing at 150 C. for 60 minutes and the heat-curing at 180 C. for 30 minutes, and also showed excellent adhesiveness and solder heat resistance. In addition, the adhesive composition of Example 12 showed excellent dielectric properties in case of the heat-curing at 150 C. for 60 minutes, and also showed good adhesiveness and solder heat resistance. Moreover, the adhesive compositions of Examples 1 to 17 and 20 to 28 had good storage stability at low temperatures.

[0174] In addition, the laminates having adhesive layer of Examples 1 to 28 were excellent in dielectric properties and storage stability, and were suppressed in warpage.

[0175] On the other hand, the adhesive compositions of Comparative Examples 1 and 9 to 12 containing only the modified polypropylene-based resin and of Comparative Example 8 with the content of the unmodified polypropylene-based resin being outside the range of the present invention had poor dielectric properties, and the storage stability at low temperatures was also poor in Comparative Examples 9, 11, and 12. The adhesive compositions of Comparative Example 2 containing only the unmodified polypropylene-based resin and of Comparative Examples 6 and 7 with the content of the modified polypropylene-based resin being outside the range of the present invention had poor adhesiveness, and were inferior in at least one of dielectric properties and solder heat resistance. The adhesive composition of Comparative Example 3 containing no epoxy resin was inferior in adhesiveness and solder heat resistance.

INDUSTRIAL APPLICABILITY

[0176] The adhesive composition according to the present invention shows good adhesiveness and storage stability at low temperatures, and is excellent in dielectric properties. The laminate having an adhesive layer using this adhesive composition exhibits little warpage even when the base film is thin; therefore the laminate is excellent in workability. Thus, the adhesive composition and the laminate with adhesive layer using the same according to the present invention are suitable for producing FPC-related products.