JPS6149114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing laminates using a novel radiation-cured resin. More specifically, a varnish consisting of a prepolymer having a terminal -SH group having a diallyl phthalate (hereinafter referred to as DAP) resin skeleton, a polyene, and a photosensitizer is applied to cloth or nonwoven fabric, impregnated and dried, and the obtained prepreg is obtained. , relates to a method of laminating with copper foil to obtain an integrated product, and curing the resin system by irradiating radiation such as ultraviolet rays or electron beams from the prepreg side to obtain a laminate.

The conventional method for obtaining DAP resin-based laminates is to first dissolve DAP・P, DAP monomers, and a thermal polymerization initiator in a solvent to create a resin varnish.
A known method is to impregnate a glass cloth or the like with this and heat and dry it to obtain a prepreg, then insert several sheets of the prepreg and copper foil laminated on one or both sides between hot plates and heat-pressure harden. ing. However, this method has poor productivity because thermal polymerization is carried out during pressing, and furthermore, DAP/P and DAP monomers have poor affinity and adhesion with glass fibers and copper foil, resulting in peeling between the base material and resin and adhesion of the copper foil. Problems such as defects were fatal, and the elongation was significantly lower than that of other resin laminates. On the other hand, DAP resin-based laminates have excellent performance not found in other resins, and it is also true that their application to laminates has been a long-held dream of the industry. High degree of electrical insulation as an example;
Examples include a high degree of dimensional stability and stability of high frequency performance over a wide range of frequencies.

On the other hand, many attempts have been made to rationally obtain laminates by impregnating base materials with acrylate or methacrylate radiation-curable resins. However, due to the following fundamental drawbacks, a method for producing a laminate using only a radiation curing method without thermal polymerization has not been put into practical use.

That is, (1) Generally, acrylate resins have extremely large curing shrinkage, and when formed into a laminate, they are prone to large warpage and twisting. Furthermore, when a large amount of inorganic filler is added to avoid this phenomenon, the radiation transmittance decreases.

(2) Reactive monomers are generally used, but their toxicity is a problem, and since a large amount of low-molecular-weight monomers are used, the stickiness cannot be removed even after drying, resulting in extremely poor workability. Further, the type of monomer is limited due to the copolymerizability of the added monomer with the prepolymer, and in addition, a homopolymer is also formed, which significantly impairs the physical properties.

(3) The oxygen inhibition effect is significant and the surface becomes uncured. In order to prevent this phenomenon, a large amount of initiator must be used, which increases the radical concentration and results in a brittle cured product.

The present inventors have conducted intensive studies to overcome the conventional drawbacks without impairing the excellent performance of DAP-based resins, and in addition, to find a method for producing a laminate using only radiation curing, and have arrived at the present invention.

That is, the allyl group of DAP・P and the mercapto group of excess polythiol are reacted in the presence of a solvent to obtain a modified DAP・P having a terminal −SH group, which is then treated with a polyene having a carbon-carbon double bond and a photopolymer. We have discovered a method using a resin varnish containing a sensitizer. When this resin system is used, the following characteristics are exhibited.

(1) Since a polyene-polythiol reaction is used, the curing shrinkage of the resin is small, and warping and twisting when forming a substrate can be completely prevented.

(2) Since the polyene-polythiol reaction is used, restrictions on polyene selection due to copolymerizability are greatly relaxed. Incidentally, the monomers used for radical crosslinking of DAP/P are:
There are only a few types such as DAP, monomer, and styrene.

(3) Since DAP/P is end-treated and modified to -SH, its compatibility and adhesion with the sheet base material are greatly improved.

(4) Since it is based on DAP/P, it has excellent film-forming properties, and the prepreg after coating and drying has no viscosity at room temperature.In addition, it is flexible and can be rolled up. It is. This greatly improves productivity.

(5) The obtained prepreg develops viscosity by increasing the temperature, so it can be laminated with copper foil, and even after curing, it has excellent adhesion to copper foil due to the -SH group.

(6) Because of the polyene-polythiol reaction, there is no oxygen inhibition effect, and only a small amount of initiator is required, which, combined with the effect of the base material, provides a tough cured product. Therefore, a so-called flexible substrate having flexibility can also be obtained.

(7) Radiation hardening such as ultraviolet rays and electron beams is possible.

The present invention is groundbreaking, as no method of manufacturing a laminate having such characteristics has been seen in the past. Details are given below.

DAP/P or isO DAP/P used in the present invention
P may be an ordinary commercially available product, and its degree of polymerization can be selected as appropriate. When considering the film-forming property after addition of polyene, DAP/P with a degree of polymerization of 5 or more is preferable.

In addition, all compounds represented by the general formula R-(SH) _o (where n is an integer of 2 to 4 and R is an organic group not containing a reactive double bond) used in prepolymerization can be used. However, preferred compounds include esters of mercaptocarboxylic acids and polyhydric alcohols, and specific examples commonly used include trimethylolpropane tristhioglycolate and trimethylolpropane (β-mercaptopropionate). , pentaerythritotetrakis (thioglycolate), pentaerythritotetrakis (β-mercaptopropionate), tris(hydroxyethyl)isocyanurate tris(β-mercaptopropionate) ethylene glycol bis(β-mercaptopropionate) ) etc. It is also possible to use these in combination.

In addition, the mixing ratio of DAP・P and/or iso DAP・P and polythiol during prepolymerization is required to be at least 2 equivalents of polythiol per 1 equivalent of DAP・P and/or iso DAP・P, and less than this. This results in the formation of a gel during prepolymerization. However, if the polythiol component is made too excessive, free polythiol will increase, and the DAP/P and/or iso DAP/P components in the final cured product will decrease, resulting in a decrease in heat resistance. Therefore, in prepolymerization, it is important to use as small an amount of polythiol as possible without forming a gel. Although the reaction proceeds even in the absence of a catalyst, it is also effective to add a radical initiator if necessary.

Furthermore, prepolymerization is usually carried out in a solvent, and the final composition is generally obtained in the form of a so-called varnish, which is DAP・P and/or iso DAP・P.
Any solvent that can dissolve DAP·P and/or iso DAP·P can be used, and it is also possible to disperse and dissolve DAP·P and/or iso DAP·P in liquid polythiol, and finally add the solvent after the heating reaction. The preferred solvent varies depending on the use of the composition, but since the varnish is applied to a sheet-like substrate and the solvent is removed by drying, a low boiling point solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone is preferable. .

Next, a polyene compound having two or more reactive carbon-carbon unsaturated bonds in one molecule is added to the thiol prepolymer thus obtained.
Thiol modification of DAP・P and/or iso DAP・P improves compatibility with various polyenes and significantly improves copolymerizability, so acrylate compounds, methacrylate compounds, and allyl compounds can be used as polyenes. Any compound can be used, but allyl compounds are preferable from the viewpoint of ease of controlling reactivity. Specific examples include triallyl isocyanurate, triallyl cyanurate, diallyl isophthalate, diallyl maleate, diallylitaconate, diallyl chlorendate, triallyl trimellitate, etc., which may be used alone or in combination. It can be used as

Furthermore, free radicals are generated by irradiating the mixture of the polythiol prepolymer solution and polyene with radiation such as ultraviolet rays and electron beams. Adding a photosensitizer,
As this compound, benzophenone, benzoin methyl ether, benzoin ethyl ether, etc. can be added alone or in combination. The amount of these added is approximately 0.01 to 3% by weight based on the total resin. It is also possible to add stabilizers, colorants such as pigments and dyes, extenders, etc. to the above composition as necessary.

The resin varnish thus obtained is applied and impregnated onto various sheet-like substrates. In this case, any sheet-like base material can be used as long as it has radiation transparency, but glass cloth, glass nonwoven fabric, polyester cloth, polyester nonwoven paper, etc. are particularly preferable from the viewpoint of radiation transparency. preferable. Also, the amount of resin applied is 30 to 70% after removing the solvent.
The weight percentage is appropriate; if it is less than 30%, poor adhesion with the copper foil will occur during lamination, and if it is more than 70%, the amount of resin flow will be large, causing trouble during lamination. After coating and impregnating, dry at a temperature below 120°C to remove the solvent and cool. After cooling, it has no viscosity at room temperature and is an excellent prepreg. Next, one or more of the obtained prepregs and the copper foil are laminated using a thermal laminator or the like. In a hot state, moderate viscosity is developed, so strong adhesiveness can be obtained. Next, the laminate is irradiated with radiation from the prepreg side to completely cure the resin. It is an extremely productive manufacturing method because irradiation for 10 seconds or less is sufficient.

In this way, an excellent single-sided metal-clad board is obtained, which can be applied to printed wiring boards, etc., and has extremely high industrial significance.

Examples are shown below.

Example 1 600 parts by weight of powdered DAP prepolymer (manufactured by Osaka Soda Co., Ltd., trade name: Daisodap A) and 400 parts by weight of methyl ethyl ketone (MEK) were mixed in five flasks to form a uniform solution.

Next, 700 parts by weight of pentaerythritotetrakis (β-mercaptopropionate) was added to this solution and reacted at a temperature of 60°C for 2 hours to form -SH
A polythiol prepolymer having a content of 2.4 m·mol/g was obtained. Next, this resin solution was cooled, and 350 parts by weight of triallylisocyanurate, 1 part by weight of benzophenone, and 1000 parts by weight of MEK were added and mixed to obtain a uniform varnish composition.

Next, apply the above varnish to the glass cloth and apply 100%
When dried at a temperature of 0.degree. C., a highly flexible prepreg with no tackiness was obtained. Two layers of the prepreg were stacked, and a 35 μm copper foil was further stacked on top of the prepreg, and lamination was performed by passing between rolls set at 150°C. An integrated laminate product with adhesive properties was obtained. Next, the laminate was irradiated with ultraviolet rays for 10 seconds using a high-pressure mercury lamp with the prepreg side facing upward. The prepreg was completely cured by irradiation, and a single-sided copper-clad board was obtained. The resulting copper laminate was highly flexible and free from warping and twisting, and could be fully used as a circuit board.

Claims (1)

[Claims] 1 Diallyl phthalate prepolymer (hereinafter
DAP・P) and/or isodiallyl phthalate prepolymer (hereinafter referred to as isO DAP・P) and the general formula R(-SH) _o (wherein R is an organic group containing no reactive carbon-carbon unsaturated bond, n is 2-4
DAP・P and/or isO is reacted with a polythiol represented by (integer of A thiol prepolymer varnish (A) containing terminal -SH and free polythiol, a polyene (B) having two or more reactive carbon-carbon unsaturated bonds in one molecule, and photosensitization. agent
A step (process) of obtaining a resin varnish containing (C) as a main component, and applying and impregnating the varnish on a sheet-like base material such as a cloth or non-woven fabric made of a fibrous material having radiation transmittance and drying it. a step of impregnating (process), and layering one or more layers of the impregnated dried material,
A process (process) of laminating with copper foil to obtain an integrated laminate; and a process (process) of obtaining a copper-clad laminate in which the side of the impregnated dry material opposite to the copper foil is irradiated with radiation to three-dimensionally crosslink and harden the resin. ) A method for manufacturing a laminate, comprising: