JPS61171739A - Production of laminate - Google Patents

Abstract

PURPOSE:To obtain a laminate having improved adhesiveness to cloth, improved mechanical strength and dimensional stability, by treating aromatic polyamide fiber cloths by plasma at low temperature, impregnating them with a polyimide adhesive, and subjecting plural sheets of the prepreg to contact bonding under heating. CONSTITUTION:Aromatic polyamide fiber cloths are treated by low-temperature plasma at 0.05-20 Torr gas pressure, impregnated with a polyimide, adhesive, dried, prepared plural sheets of prepreg are piled, and subjected to contact bonding under heating. The low-temperature plasma treatment is carried out by using a mixed gas of oxygen/nitrogen =95/5-5/95 (volume ratio). Preferably the cloths subjected to the low-temperature plasma treatment undergo surface treatment with a coupling agent containing an amino group or epoxy group. The amount of the polyimide adhesive used is 50-250pts.wt. based on 100pts.wt. cloth.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a laminate made of a cloth made of aromatic polyamide fibers and a polyimide adhesive, and particularly relates to a method for manufacturing a laminate made of a cloth made of aromatic polyamide fibers and a polyimide adhesive. The purpose is to provide a laminate with excellent mechanical strength and dimensional stability by improving the bonding strength between the two.

(Prior technology) Aromatic polyamide fibers, represented by Kevlar (trade name) cloth, have excellent properties such as low density, high strength, high elasticity, heat resistance and flame resistance, and are suitable for use in heat-resistant laminates. Although it is very useful as a material, it has poor adhesion and adhesion with resin, and improvements are desired.

In order to improve the adhesion between aromatic polyamide fiber cloth and adhesive, various chemical treatments (chemical etching, primer treatment, etc.), corona treatment, etc. have been studied in the past, but aromatic polyamide fibers themselves cannot be chemically treated. Because it is a very stable substance, sufficient effects have not been obtained.

In particular, when a polyimide adhesive is used to improve the heat resistance of the laminate, it has poor adhesion to aromatic polyamide fiber cloth, and there is a strong demand for improvement.

(Structure of the Invention) As a result of intensive study on this problem, the present inventors found that aromatic polyamide fibers were treated with low-temperature plasma at a gas pressure of 0.05 to 20 torr, then impregnated with a polyimide adhesive and dried. The inventors have discovered that a laminate with extremely excellent adhesion (adhesive) strength can be obtained by stacking a plurality of prepregs obtained and heat-pressing them, and have arrived at the present invention.

The present invention will be explained in detail below.

The method of manufacturing a novel laminate made of an aromatic polyamide fiber cloth and a polyimide adhesive proposed by the present invention has the following configuration.

The first step of the present invention is to prepare aromatic polyamide fibers from 0.05 to
Treated with low temperature plasma of 20 Torr inorganic gas. As a method for performing low-temperature plasma treatment, the aromatic polyamide fiber is held in a low-temperature plasma generation device that can reduce pressure, and high-frequency power, for example, at a frequency of 10 kHz to 100 MHz is applied between the electrodes while passing inorganic gas under low pressure. It is done by

Note that as the discharge frequency band, in addition to the above-mentioned high frequency, low frequency, microwave, direct current, etc. can be used.

In the present invention, the low-temperature plasma generator is preferably an internal electrode type, but may be an external electrode type depending on the case, or may be a coil type, capacitively coupled, or inductively coupled. Even if such a method is used, it is necessary to prevent the surface of the treated object from being altered by the discharge heat.

The method of the present invention is preferably carried out using the internal electrode method as described above, but there are no particular restrictions on the shape of the electrodes, and the input side electrode and the ground side electrode may have the same shape or different shapes. They can be either flat or ring-shaped.

Various shapes such as rod shape and cylinder shape are possible.Furthermore, it may be of the type where the metal inner wall of the processing equipment is grounded as one electrode.In addition, copper, iron, aluminum, etc. are generally used for the input side electrode. be released
°11 In order to maintain stable electricity, withstand voltage 10
It is preferable that the insulation coating is made of glass, enamel, ceramic, or the like having a resistance of 0 OOV or more. In particular, rod-shaped electrodes coated with insulation are suitable for generating locally effective plasma.

Regarding the electric power applied between the electrodes, if it is too large, the material to be treated will decompose and deteriorate due to heat generation, so it is undesirable and needs to be controlled within a certain range. In the case of , since it has excellent heat resistance, the modification effect is more pronounced when the applied power is increased, and from this point of view, it is preferable to set the power applied between the electrodes to 5 kW/r& or more.

Inorganic gases used in the present invention include helium, neon, argon, nitrogen, nitrous oxide, nitrogen dioxide, oxygen,
Examples include air, carbon oxide, carbon dioxide, hydrogen, chlorine, hydrogen chloride, sulfur dioxide gas, and hydrogen sulfide, and these gases may be used alone or in combination. However, among these gases, particularly effective gases are oxygen and nitrogen, and a mixed gas of oxygen and nitrogen is even more effective in increasing the adhesiveness of aromatic polyamide fibers.

In this case, the mixing ratio of oxygen and nitrogen is oxygen/nitrogen = 9
515-5/95 preferably 10/90-60/40
(capacity ratio). The gas pressure in the plasma generator is preferably in the range of O,OS to 20 Torr, preferably 0.1 to 10 Torr, o,
At pressures below 9 os torr, the effect of improving adhesion proposed by the present invention is small, and at pressures above 20 torr, it is difficult to maintain stable discharge and the effect of improving adhesion is small.

The aromatic polyamide fiber to be plasma treated may be treated in the form of a cord and then knitted, but in the case of the present invention, it is preferable to use commonly available cross-like materials such as plain weave, satin weave, and twill weave. .

Note that this cloth may be a combination of aromatic polyamide fibers and other fibers such as carbon fibers and glass fibers.Aromatic polyamide fiber cloths that have been treated with low-temperature plasma may be made of aromatic polyamide fibers that have been impregnated with a polyimide adhesive. Before proceeding to Step 2, pretreatment with a coupling agent having an amino group or an epoxy group provides a more stable and better adhesive effect. Coupling agents used for this purpose include γ-aminopropyltriethoxysilane, γ-ethylenediaminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
Examples include γ-glycidoxypropylmethyldimethoxysilane. These fiber cloths are impregnated or coated as an aqueous solution or an organic solvent solution with a concentration of several percent or less, and then dried. The aromatic polyamide fiber cloth that has been subjected to low-temperature plasma treatment is treated with a coupling agent if necessary as described above, and then led to the step of impregnating it with a polyimide adhesive.
It is desirable to dry the material sufficiently by heating it at 00 to 150°C or storing it in a drying room.

As the polyimide adhesive, a polyimide resin oligomer dissolved in a solvent is generally used. A tack-free adhesive-coated aromatic polyamide fiber cloth is formed by impregnating and coating an aromatic polyamide fiber cloth with this material and pre-drying it.

Examples of the above-mentioned polyimide adhesive include:

Polyamino bismaleimide, which is a reaction product derived from , is used as a useful adhesive and is commercially available under the trade name Kelimide 601. By adjusting the amount of adhesive impregnated onto the aromatic polyamide fiber cloth in the range of 50 to 250%, preferably 80 to 200%, based on the weight of the fiber cloth, a laminate with extremely excellent interlayer adhesive strength can be obtained. Below 50%, the adhesive strength decreases rapidly. 11.This is a big difference compared to conventional glass cloth and Kevlar cloth, in which laminates were made with a resin adhesion of 30 to 60%. This is one proof of the uniqueness of aromatic polyamide fiber cloth.

The reason why the amount of polyimide adhesive impregnated in the present invention is required to be 50% or more, especially 80% or more is that the aromatic polyamide fiber cloth is subjected to low temperature plasma treatment, so that the wettability and affinity for the polyimide adhesive is improved. It is speculated that this is because the amount of adhesive that permeates into the fibers increases, and as a result, the amount of adhesive that contributes to the adhesion and adhesion between the cloth layers becomes insufficient with the conventional amount.

The polyimide adhesive is diluted with a solvent selected from N-methylpyrrolidone, methyl glycol acetate, dimethylformamide, etc. to a concentration of about 40 to 70% before use.

The prepreg obtained by impregnating with the above polyimide adhesive is dried to remove the solvent component.
This drying is required to be carried out under conditions that maintain the fluidity of the polyimide adhesive during pressure molding. Although the temperature and time of this drying vary depending on the activity of the adhesive resin and the solvent used, it is usually carried out at 110 to 160°C for 5 to 30 minutes.

A predetermined number of prepregs manufactured in this manner are stacked together and then transferred to the third step, which is a pressing step (pressure forming). As for the pressing conditions, it is important to make the distribution of the resin in the laminate uniform, and for this purpose, a method is used in which the resin is pressed and hardened while being made to flow. Appropriate pressing conditions include preheating at 130-180°C and 0-50 kg/ffl, followed by curing at 180-230°C and 10-50 kg/aJ.

In order to sufficiently proceed with curing, press time is 30 minutes or more.
It takes 3 hours.

The formed laminate is transferred to a fourth step, an after-cure step, in order to fully cure and remove unnecessary volatile components. The after-cure conditions are preferably set within a range from the press temperature to a temperature about 30° C. higher, and the temperature is maintained at the same temperature for 1 to 20 hours. Of course, it is also possible to omit the after-cure step by allowing sufficient pressing time.

The laminate obtained by the method of the present invention has excellent thermal conductivity, heat resistance, and dimensional stability, and also has improved interlayer adhesion between aromatic polyamide fiber cloths, so it has excellent bending strength, bending modulus, etc. It also has excellent mechanical properties. For this reason, it is useful as a structural material that requires heat resistance and dimensional stability. In particular, copper-clad laminates made by bonding copper foils are required to be multilayered due to their heat resistance, dimensional stability, and thermal conductivity. The objective is to provide a material that can fully meet the needs of the industry as a multilayer print base material.

A detailed explanation will be given below with reference to examples.

Example 1 (Experiments Na 1 and &2) After setting a Kevlar cloth [Kanebo Co., Ltd. K-120 (SC-11)] into the processing tank of a low-temperature plasma generator, the pressure was reduced using a vacuum pump. It was lowered to 0.01 Torr. In this state, a mixed gas of oxygen/nitrogen = 173 (volume ratio) was introduced, and the pressure was adjusted and maintained at 0.3 torr.
A power of 110 kHz and 25 kV was applied and the treatment was carried out for 1 minute.

The thus treated Kevlar cloth was impregnated with a 50% N-methylpyrrolidone solution of Kelimide 601 (manufactured by Nippon Polyimide Co., Ltd.), and then heated at 150° C. for 15 minutes to prepare a prepreg.

The amount of resin impregnated at this time was 100%.

After stacking 10 sheets of this prepreg and setting 35μ electrolytic copper foil (manufactured by Nippon Mining Co., Ltd.) on the top and bottom,
Press molding was performed for 1 hour under the condition of 25 kg/a#.

After cooling, the molded product was taken out and after-cured at 200°C for 3 hours, and the interlayer adhesion between the cloths was measured (
Experiment Nα1). Note that the interlayer adhesive strength of a similarly molded laminate was measured using untreated Kevlar cloth (Experiment Nci2).

Example 2 (Experiment Nα3) After a Kevlar cloth [Kanebo Co., Ltd. K-120 (SC-11)] was placed in the processing tank of a low-temperature plasma generator, the pressure was reduced with a vacuum pump to 0.01. I lowered it to a torque. In this state, introduce oxygen gas and reduce the pressure to 0.3
, /L/ ,: W□9. □, 1,. ,□2.25kl
1 (71t) was applied and treated for 1 minute. The interlayer adhesive strength of the Kevlar cloth treated in this way was measured in the same manner as in Example 1 (Experiment No. 3).

Example 3 (Experiment!!14 and Experiment &5) A Kevlar cloth [-120 (SC-11) manufactured by Kanebo Co., Ltd.] was set in the processing tank of a low-temperature plasma generator.

Thereafter, the pressure was reduced to 0.01 Torr by using a vacuum pump. In this state, a mixed gas of oxygen/nitrogen = 4/1 (volume ratio) was introduced, the pressure was adjusted and maintained at 0.6 torr, and then a voltage of 110 kHz and 20 kW was applied for 30 seconds. The Kevlar cloth treated in this way has a solvent composition of N-methylpyrrolidone/dimethylformamide=
50% concentration of kelimide 6 consisting of 3/1 (weight ratio)
After impregnating with the 01 solution, a prepreg was prepared by heating and drying at 130° C. for 30 minutes.

The amount of resin impregnated at this time was 130%.

After stacking 10 sheets of this prepreg and setting 35μ rolled copper foil (manufactured by Nippon Mining Co., Ltd.) on the top and bottom,
Press molding was performed for 1.5 hours at 20 kg/cd.

After cooling, the molded product was taken out and after-cured at 200°C for 2 hours, and the interlayer adhesion between the cloths was measured (
Experiment Nα4), using untreated Kevlar cloth, the interlayer adhesion of a similarly molded laminate was measured (Experiment Na 5 ).

The above experimental results are summarized in Table 1.

Table 1 Method for measuring interlayer adhesion strength IQIX12Q from the center of the laminate! After cutting 1 sample piece and peeling off the upper and lower copper foils, the peel strength between the cloths was set to 1.
Measurement was performed by peeling at 80°. Note that the tensile speed was 5 m/min.

Measurement of resin impregnation amount weight of P2: Weight of Kevlar cloth

Claims (1)

[Claims] 1. Aromatic polyamide fiber cloth is heated to a gas pressure of 0.05 to
A method for manufacturing a laminate, which comprises stacking a plurality of prepregs obtained by treating with low-temperature plasma at 20 torr, impregnating with a polyimide adhesive and drying the prepregs, and then heat-pressing the prepregs. 2. The above low temperature plasma treatment is performed with oxygen/nitrogen = 95/5 to 5.
2. The manufacturing method according to claim 1, wherein the manufacturing method is carried out using a mixed gas of /95 (volume ratio). 3. The above prepreg is aromatic polyamide fiber cloth 10
The manufacturing method according to claim 1, characterized in that the polyimide adhesive is contained in an amount of 50 to 250 parts by weight per 0 parts by weight.