JPH0222049A - Continuous preparation of fire-retardant unsaturated polyester resin/paper/copper-clad laminated sheet - Google Patents

Abstract

PURPOSE:To form a fire-retardant laminated sheet by laminating a specific unsaturated polyester resin to a paper base material treated with aqueous varnish containing a fire retardant and further laminating a copper foil to the formed laminate through an adhesive layer before curing. CONSTITUTION:A liquid unsaturated polyester resin containing halogen and phosphorus, having viscosity of 20 poise/20 deg.C or less and a thixotropy index of 1.2-2.5 and containing organonitrogen and/or an inorg. fire-retardant aid is laminated to a paper base material treated with aqueous varnish of a thermosetting resin containing one or more kind of a component selected from a nitrogen-containing type phosphorous and/or halogen-containing org. compound and an inorg. fire retardant. Next, a copper foil or cover film is laminated to the formed laminate through an adhesive layer and the laminated structure is continuously passed through a heating/drying oven under contact pressure by a roll laminator to be cured and integrated to prepare an unsaturated polyester/paper/copper clad laminated sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for continuous production of a flame-retardant unsaturated polyester resin-paper-copper clad laminate.

[Prior Art] With the recent rapid development of the electronics industry, the demand for copper-clad laminates for printed wiring circuits has rapidly increased, and the proportion of flame-retardant types has increased significantly. Therefore, there is a strong demand in the industry for an efficient mass production method, but the conventional manufacturing method of dry prepreg by lamination molding using a high-pressure press increases the equipment cost significantly and requires a large number of manufacturing man-hours. Therefore, improvement is desperately desired.

On the other hand, the so-called wet continuous lamination method using liquid unsaturated polyester resin has traditionally been a manufacturing method suitable for mass production, and has only been applied to a very limited number of fields. Ta. However, with the remarkable development of electronics technology in recent years, it has come to be valued more for its energy and labor savings. Nowadays, the huge demand for copper-clad laminates for printed wiring circuits has made it advantageous to introduce the continuous lamination method in this field as well.

It has been difficult to make unsaturated polyester resins flame retardant because the resin itself has the disadvantage of being more easily combustible by -C than phenol resins. Moreover, when the present invention is based on a continuous lamination method, it is even more difficult to achieve both ease of automatic adjustment of operating conditions.

[Purpose of the invention]

As a result of various studies on these points, the inventors of the present invention found that the components of the laminate include halogen-based, nitrogen-based, and phosphorus-based substances that have flame retardant effects in a well-balanced manner, and in as little amount as possible. We have discovered that this is a necessary condition, and have arrived at the present invention.

(Structure of the Invention) The present invention impregnates a paper base material that has been undercoated in advance with a liquid unsaturated polyester resin, and uses a cover film to continuously produce a contact pressure copper-clad laminate. The halogen content (converted to Br) of the material laminate (converted to the weight excluding copper foil) is 5.0 to 20.0% (weight, the same hereinafter), and the nitrogen content is 0.8 to 8.0%. , a method for producing a flame-retardant unsaturated polyester resin-paper-copper-clad laminate, characterized in that the blending amount of each of the above components is adjusted to a phosphorus content of 0.4 to 2.0%.

In general, the continuous manufacturing method for combustible unsaturated polyester resin low tensile strength plates is a one-step method (see Figure 1). When laminating impregnated base materials, one layer is covered with a cover film and the other layer is covered with copper foil. This is a method for producing copper-clad boards in one step.

In the present invention, in order to impart flame retardancy to the obtained paper base laminate, the halogen content (in terms of Br) must be set to 5.0.
~ 20.0%, it is necessary to adjust the nitrogen content to 0.8 to 8.0%, and the phosphorus content to 0.4 to 2.0% (laminated layer excluding copper foil). (Based on board weight)
.

To adjust to such a value range, the content of halogen, phosphorus, and nitrogen in the Φ resin, the content of halogen, phosphorus, and nitrogen in the O undercoat resin, and the undercoat resin in the O undercoat treated paper base material must be adjusted. content and the resin content in the impregnated substrate need to be considered in each context.

In order to achieve flame retardancy through the synergistic effect of the combination of three types of elements, we reduce the amount of halogen as much as possible, which has the most negative effect on electrical properties and heat resistance (especially high-temperature, long-term durability). The aim is to improve the stability of the system. Special feature: In this continuous lamination method, in order to automate and make the process continuous, curing can be done in an extremely short period of time and steadily compared to batch lamination methods such as the normal pressure press method. The important point is to ensure that the resin is heat-stable.

The unsaturated polyester resin used in the present invention contains halogen and phosphorus.

First, in the present invention, it is preferable that the halogen contained in the unsaturated polyester resin constitutes the main component of the resin. That is, as the halogen-containing unsaturated polyester resin, a halogen-containing dibasic acid (or its acid anhydride)
and a so-called halogen-containing unsaturated polyester oligomer (800 to 5,000 in number average molecular weight) containing acid residues of α and β unsaturated dibasic acids that do not contain halogen.
This is a liquid resin obtained by melting the above into a liquid polymerizable monomer whose main component is styrene and/or a styrene derivative containing a halogen group.

As the halogen, chlorine and bromine are preferred. In general, bromine has a greater flame retardant effect, and the weight ratio of chlorine to bromine, which provides the same effect, is approximately 1:2. In other words, since bromine can provide approximately the same effect as chlorine at 1/2 (weight), by utilizing this relationship, in the present invention, all halogen contents are defined in terms of the weight of bromine.

In addition, as the polymerizable monomer pair that is another component of the unsaturated polyester resin, difunctional monomers such as styrene are usually used, but polyacrylates (or It is preferable to contain a small amount of a polyfunctional monomer such as polyacrylate for modification, since the properties of the resin (especially heat resistance and chemical resistance) are significantly improved.

(8) A polymerizable monomer containing at least one of halogen, phosphorus, and nitrogen may be used as appropriate. Halogen-containing unsaturated polyester oligomer and polymerizable monomer (halogen-containing,
In addition to being a mixture with any halogen-free
A general unsaturated polyester resin composed of a halogen-free unsaturated polyester oligomer and a monomer may be blended with an organic halogen-containing additive as appropriate.

Furthermore, an epoxy acrylate type resin or a halogen-containing type thereof may be used instead of the above-mentioned general unsaturated polyester resin.

The various halogen-containing unsaturated polyester resins described above preferably have a halogen content (in terms of Br) of 5% or more, and the amount can be adjusted in advance as appropriate depending on the resin content of the paper base laminate. Adjustment is necessary.

In the present invention, the flame retardance is low due to the use of a resin with a high halogen content, but if it is exposed to high temperatures during curing, processing, and mounting on equipment. Since it has the drawback of easily deteriorating performance due to thermal decomposition and damaging equipment due to generated gas, its usage should be kept to the minimum necessary.In the present invention, not only halogen groups but also coexisting phosphorus The aim is to minimize the amount used in relation to nitrogen-containing groups and nitrogen-containing groups.

Next, in the present invention, the phosphorus contained in the unsaturated polyester resin is an organic compound of the following additive type, and contains groups reactive with the unsaturated polyester resin, halogen-containing, nitrogen-containing It may have a group of

(RO) 3PO type (phosphate type, including halogen-containing types), ! ! (RO) JPO type (phosphonate type, including halogen-containing and/or nitrogen-containing types), iii R, RO type (phosphine oxide type), +
v R3P type (phosphine type), V(RO)3P type (phosphite type), vi others (condensed type, quaternary phosphonium salt, etc.) where R= CH2CH2Cj2 n=1-3 R4P''C1-: Tetrakis (Hydroxymethyl)phosphonium chloride (R: CH, OH) The phosphorus-containing unsaturated polyester resin containing the above-mentioned organic phosphorus compounds preferably has a phosphorus content of 0.5% or more, and is suitable for use as a paper base in the form of a final product. It is necessary to appropriately adjust the amount in advance depending on the resin content of the material laminate.

The higher the phosphorus content, the better for flame retardancy;
Since it is easy to cause other performance deterioration, it is better to minimize the amount as much as possible. Furthermore, among the phosphorus compounds, halogen-containing and/or nitrogen-containing types are preferred because they are more effective.

Further, phosphorus compounds are preferable because they have the function of improving the thermal stability of halogen groups.

The phosphorus-containing halogen-unsaturated polyester resin used in the present invention is preferably further blended with a nitrogen-containing organic compound, if necessary, since flame retardance can be efficiently imparted with a smaller amount of halogen.

As the nitrogen-containing compound, amine resins, thermosetting acrylic resins, polyamide resins, etc. that have good compatibility with unsaturated polyester resins may be blended as appropriate, and halogen-containing compounds and/or phosphorus-containing compounds may be used. Among the compounds, nitrogen-containing types may be used as appropriate. The nitrogen content should be adjusted for the paper base laminate as a whole in relation to the amount introduced by the base coat resin of the paper base. The smaller the amount of the nitrogen-containing water-soluble thermosetting resin used as the undercoat resin for the paper base material, the less the amount of nitrogen contained in the laminate, and therefore the larger the amount of nitrogen in the impregnating resin is required.

The unsaturated polyester resin used in the present invention needs to contain halogen, phosphorus, and (if necessary, nitrogen) as described above, but also has a viscosity of 20% po to be suitable for the continuous lamination process. /20℃ or less, thixotropy, 2 to 2.
Must be 5.

In general, the lower the resin viscosity is, the more quickly and completely the liquid resin can be impregnated into the base material and defoamed using roll lamination, which is advantageous. During the process of coating the base material and heating and curing it under contact pressure using rolls (or double belt conveyor) and passing through a heating furnace, the sealing at the edge end was insufficient, resulting in resin liquid flowing out and air bubbles entering the laminated base material. This has the drawback that it becomes easy to re-enter, making it difficult to obtain a void-free laminate (cured product).

On the other hand, if the resin viscosity is high, it will be relatively easy to seal the edge end, preventing the resin liquid from flowing out and bubbles from re-entering the laminated base material, but on the other hand, the rate of resin impregnation into the base material will be slow. Moreover, the impregnation becomes insufficient, and in this case as well, it is difficult to obtain a void-free laminate (cured product).

In any case, it is extremely difficult to try to improve this point simply by adjusting the viscosity, but if the resin is given appropriate probing properties, even if the resin has a low viscosity, the seal at the end of the ear can be improved. This makes it possible to avoid re-infiltration of air bubbles. In order to achieve both impregnating properties and sealing properties, the viscosity should be 20 poise/20'C or less, and the thixotropy range should be from 1.2 to 2.5.

In addition, the measurement force of thixotropy (using a Pluta field viscometer)
is as follows.

Thixotropy - (apparent viscosity at 6r, P, m)/(60r,
(Appearance at Pom is viscosity) The viscosity is 60r, and the appearance at P and m is viscosity.

Additives that impart thixotropic properties to resins include fine particle silicas, short fiber ashests, hentonites,
Hydrogenated castor oil and the like can be used in the same manner.

However, particulate silicas are particularly preferred because their thixotropic properties do not easily deteriorate even when heated. Furthermore, since it is easier to impart thixotropy as the viscosity is lower, it is desirable to keep the viscosity as low as possible.

However, flame-retardant resins, especially halogen-containing resins, generally have a high viscosity, and the following methods are used to reduce the viscosity.

■ Introducing flexible long-chain aliphatic dibasic acid or diol residues into chlorine-containing unsaturated polyester oligomers, ■ Increasing the amount of crosslinking monomers, ■ Increasing the amount of reactive plasticizers. Addition, ■ Formulated with low clay general purpose unsaturated polyester resin.

Also a surfactant in the resin to promote impregnation.

A wetting agent, a defoaming agent, etc. may be added as appropriate.

The liquid unsaturated polyester resin used in the present invention is preferably defoamed and deaerated prior to being impregnated into a base material.

In general, it is somewhat difficult to degas and degas the resin with thixotropic properties, so in the present invention, this is achieved by the action of ultrasonic waves (10 to 50 kHz) rather than by vacuum. It is preferable to carry out this method because it can reduce the loss of polymerizable monomers such as styrene and can be achieved in a short time (if necessary, continuously while flowing through the tube). Further, for this purpose, a conventional defoaming agent such as silicone-based or fluorine-based defoamers may be appropriately blended with the resin. In addition, the resin for Kelco-1 has a viscosity of 1 to 20 poise (20°c) and a thixotropy of 1.5 to 4.0.
It is desirable that

The halogen-containing and phosphorus-containing unsaturated polyester resin of the present invention is
Furthermore, if necessary, it is preferable that an organic tin compound and/or an epoxy compound be appropriately added as a stabilizer. Thermal decomposition of halogen-containing unsaturated polyester resin during processing steps such as soldering of copper-clad laminates within the temperature range of 200°C to 300°C, accompanied by the elimination of halogens, is further accelerated by the generation of thermal decomposition products. There is a tendency to Therefore, it is extremely important to suppress the initial decomposition of halogen groups in the semi-high temperature range up to 300°C, and organotin compounds and epoxy compounds greatly contribute to improving the thermal stability of resins in this respect. It is.

Examples of the organic tin compound include tin salts of soluble organic acids, dialkyltin fatty acid salts, and dialkyltin sulfur compound salts.

The epoxy compound is a low-molecular compound with good compatibility such as an alicyclic epoxy resin or glycysyl methacrylate.

The amount of the stabilizer made of these organic tin compounds and/or epoxy compounds is preferably 5 to 80% based on the halogen content (in terms of Br) of the resin. If the amount is less than this, the effect will be significantly reduced, and if it is more than this, the properties of the resin may be deteriorated, so neither is preferable.

The paper base material used in the present invention may be cotton linter paper, sulfide paper, kraft paper, etc., but in order to further improve flame retardancy, an inorganic flame retardant aid is added to the paper in advance. It is preferable to use a so-called flame-retardant paper.

This is advantageous because the desired flame retardancy can be achieved even with a lower halogen content in the laminate.

Examples of the inorganic flame retardant aid used in the present invention include antimony compounds, zinc compounds, thread compounds, aluminum compounds, and zirconium compounds.

Among these, antimony-based compounds, especially antimony oxide and antimony pentoxide (especially advantageous because they do not contaminate the plating bath), are preferred because they are effective even in relatively small amounts.

For antimony compounds, the content is preferably 0.5 to 10% (internal cutting, dry base). If the amount is less than this, the flame retardant effect will hardly be noticeable, and if the amount is more than this, the effect will not be much different, and the properties of the paper (especially resin impregnation) will deteriorate and the cost will increase significantly. Undesirable. Furthermore, antimony compounds are toxic and must be handled with care.

In addition, for materials such as boron threads and aluminum compounds that are intended to be flame retardant through the action of heat absorption and generated water vapor due to the release of a large amount of crystallized water and hydrated water during heating, paper The effect will not be fully exhibited unless the amount added is quite large. For example, hydrated alumina requires a content of 50 to 90% (based on papermaking).

A zirconium compound alone has a slightly lower effect than an antimony compound, so it is preferable to use it in combination with an antimony compound.

In contrast to this method, these inorganic flame retardant aids are added and dispersed in halogen-containing phosphorus-containing unsaturated polyester resin in advance, and ordinary paper without these inorganic flame retardant aids is added. It is also possible to achieve the same flame retardant effect using a base material.

However, in the latter method, in general, the inorganic auxiliary agent dispersed in the resin tends to settle due to the difference in specific gravity and is difficult to maintain in a uniform state.As a result, when it is coated and impregnated on paper, it tends to become uneven, resulting in poor performance. Of course, even the appearance is likely to be defective.

The use of paper is preferable because it does not have such problems at all, and it is possible to make the distribution of the inorganic auxiliary agent in the laminate uniform and to reduce variations in performance.

In the present invention, any thermosetting resin used in the undercoating process may be used as long as it is water-soluble or water-dispersible, contains nitrogen, and does not contain a component that inhibits radical polymerization. I can do it.

In addition to amino resins, the undercoating resin used in the present invention may be formaldehyde condensation products of prepolymers such as polyethyleneimine, polyacrylamide, polyamide/polyamine/epichlorohydrin, etc., which are water-soluble and thermosetting. May be used.

Further, these nitrogen-containing water-soluble thermosetting resins may be further appropriately modified with epoxy resins, unsaturated polyester resins (including alkyd resins), ketone resins, and the like.

Furthermore, the undercoat resin of the present invention needs to be a flame-retardant type resin containing nitrogen, but it is preferable that it is further made flame-retardant by also appropriately containing halogen and phosphorus.

The adhesive for copper foil used in the present invention preferably has a combination of an elastomer and a thermosetting resin in order to achieve both beer strength and heat-resistant solderability of the copper foil.

For purposes of the present invention, combinations such as nitrile rubber-epoxy resin-phenolic resin, nitrile rubber-phenolic resin, nitrile rubber-epoxy resin, nitrile rubber-polyurethane rubber-epoxy resin, non-grade polyamide resin-epoxy resin, etc. is preferred.

For the purpose of the present invention, the adhesive may be appropriately blended with additive flame retardants and flame retardant aids such as the halogen-based, phosphorus-based, nitrogen-based, and antimony-based flame retardants, or the adhesive resin may It is preferable to use a halogen-containing material to make it flame retardant.

Examples will be explained below.

〔Example〕

Example 1 The various raw materials used are as follows.

■ Unsaturated polyester resin (shown in Table 1) Table 1
Unsaturated polyester resin and curing catalyst (Mi composition) Maleic acid 0.5 mol, chlorendic acid 0.5 mol, propylene glycol 0.5 mol butylene glycol 05 mol (molecular weight) Mn: I, 600 (equivalent to acid value 35)
Pass Diethyl N, N-bis(2-biloxyethyl)aminomethylphosphate - styrene/triallyl cyanurate/trimethylolpropane triacrylate -7/2/1 ■ Paper base material: Kraft paper, thickness 0.30 mm, medium 1.0
5-layer wet strength 0.25kg/15+nm, water absorption 100
mm/10 minutes■ Resin water-based varnish for undercoat: Resin solution nitrimethylolmelamine is 30% in a 2/1 mixed solvent of methanol/water? Liquid phosphorus compound Nidris (3,4 dibromopropyl) phosphate Antimony oxide N% in cured product of this varnish = 273% 2%: 1.3%
, Br%: 20.6%, Sb203%: 5.0% ■ Copper foil: continuous type, electrolytic copper, width 1.05 m, thickness 35 microns, surface roughening ■ Copper foil adhesive: Same as Example 1 (2) Covering film: A copper-clad laminate was continuously produced using a raw material of a polyethylene terephthalate sheet, 1.2 m in diameter and 60 microns or more thick, according to the process flow shown in Figure 1.

The second section shows the test items and performance of intermediate materials in the intermediate process of undercoating the paper base material, impregnating it with resin, and laminating and degassing it.
As shown in the table.

Next, the copper-clad laminate (
The operating conditions in the intermediate steps leading to the final product are shown in Table 3.

Table 2 Intermediate process and intermediate materials 100-140℃ 1) 0 minutes, hot air drying oven 1 Roll coater H, use of roll laminator before impregnation 1) 140℃ 30 minutes (long drying) Bee H Cow) is ultrasonic (
Table 3 Conditions for copper clad adhesion and curing process (Note) The performance of the copper clad laminate (1) obtained by hammering 1 row U layer thickness 40 microns is as shown in Table 4. .

Example 2 A copper-clad laminate (II) was obtained in exactly the same manner as in Example 1, except that 1% dibutyltin dilaurate (based on the resin) was added to the unsaturated polyester resin used in Example 1. The properties of the obtained copper-clad laminate (II) were almost the same as those of laminate (1), but discoloration in a long-term durability test of 1) 000 hours at 150°C was significantly suppressed, and the decomposition of halogen groups was significantly suppressed. It can be seen that this is significantly suppressed.

Comparative example 1 The various raw materials used are as follows.

■ Unsaturated polyester resin: (shown in Table 5)
Performance of surface copper-clad laminate (1) Paper base material; same as Example 1 (2) Resin water-based varnish for undercoat Note that the nitrogen content in the cured resin product is 39.0%.

■ The copper foil, copper foil adhesive, and cover film were all the same as in Example 1.

A copper-clad laminate was continuously produced using the above raw materials and following substantially the same process flow as in Example 1. The test items and performance of the intermediate material are shown in Table 6.

Table 5 F1iiiIDd; IJ ester resin and curing catalyst No. 6
The conditions for the surface intermediate process and the intermediate process leading to the production of intermediate materials and copper-clad laminates (products) are the same as in Example 1. The performance of the obtained copper clad laminate is shown in Table 4.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a continuous production method of an unsaturated polyester resin paper-copper clad laminate using a one-step process.

Claims (4)

[Claims] (1) Contains halogen and phosphorus and has a viscosity of 20 poise/20
℃ or less, a thixotropy of 1.2 to 2.5, and a liquid unsaturated polyester resin containing organic nitrogen and/or an inorganic flame retardant. A paper base material treated with a water-based varnish of a thermosetting resin containing at least one selected from the group consisting of an organic compound and an inorganic flame retardant is impregnated and laminated, and the laminated material and an adhesive layer are laminated. An unsaturated polyester-paper-copper-clad laminate characterized by laminating copper foil and/or a cover film through a roll laminator and curing and integrating the sheets through a heating drying oven under continuous contact pressure using a roll laminator. In the manufacturing method, the halogen content (in terms of Br) is 5.0 to 20.0% based on the paper base laminate (in terms of weight excluding copper foil).
(weight, same below), phosphorus content 0.4-2.0%
Continuous production of a flame-retardant unsaturated polyester resin-paper-copper clad laminate, characterized in that the blending amount of each of the above components is adjusted so that the nitrogen content is 0.8 to 8.0%. Method. (2) The paper base material is preliminarily coated with an inorganic flame retardant additive of 0.5 to 10%.
The flame-retardant unsaturated polyester resin according to claim (1), which is a 0% (dry base) infused resin.
Continuous manufacturing method for paper-copper clad laminates. (3) The method for continuously producing a flame-retardant unsaturated polyester resin-paper-copper-clad laminate according to claim (2), wherein the inorganic flame retardant aid is antimony-based. (4) The unsaturated polyester resin containing halogen and phosphorus is further treated with an organotin compound and/or an epoxy compound as a halogen group stabilizer.
The flame retardant unsaturated polyester resin according to claim (1), which contains 5 to 80% of the flame retardant unsaturated polyester resin
Continuous manufacturing method for paper-copper clad laminates.