JPS624407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel photocurable prepreg resin composition. More specifically, the present invention relates to a resin composition used for manufacturing a photocurable prepreg tape.

The photocurable prepreg tape is wrapped around the article,
Since it is completely cured by irradiation with light, it is suitable for binding of articles with a large heat capacity. It is also effective for items for which heating is inappropriate.

Conventional prepregs of this type are made by impregnating a base material such as a glass tape with thermosetting resin, thermoplastic resin, and an organic solvent that dissolves them, and heating it to evaporate the organic solvent. Thermosetting resins are also partially chemically reacted (referred to as B-staged).

In this case, the following properties are required for the prepreg.

(1) The surface of the prepreg tape is non-sticky.
It also has excellent processing workability, such as being flexible and able to be sufficiently tightened when wrapped around an article.

(2) After winding, it hardens quickly by heating.
The cured product must have excellent mechanical properties (creep resistance, strength, etc.), heat resistance, and even oil resistance.

(3) Manufacturing costs are low.

However, when preparing the prepreg manufactured by the above-mentioned method, if heating is continued during B-staging, the curing reaction will progress and the prepreg will reach the C-stage. Not only is it difficult to maintain a constant prepreg condition at all times, but even after winding the product, it is
It requires heating for 16 hours, which is particularly undesirable for binding articles with a large heat capacity.

The present inventors have conducted extensive research to overcome the above-mentioned drawbacks, and have found that polyvinyl formal ,
Phenoxy resin or mixed polymer of both 10~40
When using a photo-curable prepreg resin composition containing a modified epoxy resin obtained by reacting epoxy resin at a temperature of 150 to 230°C, an organic solvent, and a compound that generates a Lewis acid upon light irradiation, prepreg manufacturing It was discovered that a stable prepreg product can be produced during the process, and that when the prepreg is used, it can be easily completely cured by irradiation with light, leading to the completion of the present invention.

The epoxy resin having at least two or more epoxy groups in the molecule used in the present invention only needs to have excellent properties as a cured product.
30th, published by Shokodo) can be used without any special restrictions, and it is also permissible to include epoxy compounds containing one epoxy group in the molecule as a diluent. Such epoxy resins are highly viscous to semi-solid prepolymers, and good prepregs cannot be made from resin compositions based on these prepolymers alone. The reason for this is that the prepreg tape is sticky and has disadvantages such as significantly poor workability and low adhesive strength that causes the prepreg tape to fall apart.

The present inventors conducted studies to improve this drawback and found that it is sufficient to partially blend linear polymers. However, many linear polymers have poor compatibility with epoxy resins, causing them to separate when mixed, and becoming cloudy when made into prepregs, resulting in a significant decrease in photocuring ability. A lot of things happened. The present inventors continued their studies under these circumstances, and found that linear polymers such as polyvinyl formal or phenoxy resin, which are highly polar and have functional groups such as hydroxyl groups in their molecules, can be used as epoxy resins. It has been found that compositions blended with 100% and 300% form relatively good prepregs. However, when such linear polymers are used, the resin composition gradually undergoes phase separation over a long period of time (approximately 10 to 14 days later, it appears to be in a gel state), and it becomes impossible to impregnate the base material. . Such a phenomenon is remarkable when polyvinyl formal is used. In addition, in any blend system, the photocured product is not a complete three-dimensional network structure, but rather an aggregate in which crosslinked polymers and linear polymers coexist; The macromolecules are extracted. This is disadvantageous in terms of chemical resistance, etc., and there is also a need for improvement in terms of a decrease in elastic modulus at high temperatures due to a decrease in crosslinking density of the cured product system.

Therefore, as a result of further investigation, the present inventors found that
The composition of the present invention has been arrived at. In other words, if a modified epoxy resin obtained by reacting polyvinyl formal or phenoxy resin with an epoxy resin at high temperatures is used, phase separation can be prevented and stability can be achieved over a long period of time. In addition, the properties of the cured product, such as a high elastic modulus at high temperatures, are superior to blends. This is thought to be due to chemical bonding between the linear polymer and the epoxy resin.

Next, the effects of polyvinyl formal and phenoxy resin and their blending amounts will be explained. A prepreg made from a resin composition using polyvinyl formal becomes highly flexible and strong. On the other hand, when phenoxy resin is used,
It becomes a hard cured product with extremely high hardness. Therefore, both resins may be selected depending on the purpose and use, and if they are used in combination, it is convenient to prepare a wider variety of cured products. The blending ratio of these linear polymers is 90 to 60 parts of epoxy resin.
It is suitable to select within the range of 10 to 40 parts, and 10
If the amount is less than
When the amount is more than 40 parts, the viscosity of the resin composition increases significantly, making it necessary to increase the degree of dilution with the solvent, resulting in a resin composition with a low solid content, both of which are unfavorable.

The modified epoxy resin is prepared as follows. While stirring the epoxy resin charged in a conventional resin production kettle, polyvinyl formal, phenoxy resin, or a mixed polymer of both is gradually added and dissolved. In this case, the polymer may be supplied in the form of a solid powder or pellet, or it may be supplied in the form of a solution in which it is preliminarily dissolved in a solvent. In the former case, the contents are gradually heated and dissolved uniformly. In the latter case, the solvent is distilled off while increasing the temperature. In this way, the temperature is raised while both are homogeneously dissolved, and finally, heating is continued at a high temperature of 150 to 230°C for usually several hours to prepare a modified epoxy resin.

The modified epoxy resin thus obtained is a mixed system of epoxy resin a, linear polymer b, and partial reactant c of a and b. If the operating temperature is lower than 150° C., the final composition will have a tendency similar to that of the blend system described above, which is not preferable. On the other hand, the temperature at which it acts
If the temperature is higher than 230°C, the epoxy resins will react with each other and there is a risk of gelation, which is also undesirable. The most suitable condition is 160 to 210.
It is preferable to allow the reaction to take place at ℃ for 3 to 5 hours. The modified epoxy resin thus obtained is a mixture of a, b and c, as described above. Here, specific examples of such modified epoxy resins will be shown.

100 g of bisphenol A type epoxy resin (manufactured by Ciel Chemical Co., Ltd., Epicoat 828, molecular weight approximately 380, epoxy equivalent approximately 190) and polyvinyl formal (hereinafter referred to as
PVF) (manufactured by Chitsuso Co., Ltd., Vinylex F's E)
About the modified epoxy resin, 30g of type, molecular weight approx. 43000) was reacted at 190℃ for 4 hours, methanol, which is a poor solvent for PVF and a good solvent for epoxy resin (Epicote 828), was added. was precipitated, and the precipitate was thoroughly washed with methanol and dried under vacuum. The weight of the precipitate thus treated showed an increase of about 7 g. The precipitate was then extracted using methyl ethyl ketone, a strong solvent for epoxy resin, resulting in approximately 5 g of epoxy resin (Epicote).
828) were extracted. These results indicate that the modified epoxy resin is a mixture of a, b, and c as described above, and that the PVF precipitate is
This indicates that a considerable amount of epoxy resin is contained inside. Polymer solution theory shows that macromolecules, which are macromolecules, form entangled bonds in concentrated solutions, and these entanglements cannot be easily disentangled. In the modified epoxy resin of the present invention, such entanglement also occurs between PVFs, which are macromolecules, and between PVFs.
This is thought to be the reason why a considerable amount of epoxy resin was included in the precipitate. It is thought that by using such a modified epoxy resin, the affinity between the constituent components of the resin composition is improved, and as a result, a photocurable resin composition with good compatibility is produced.

The temperature of the modified epoxy resin prepared as described above is lowered to about 100°C, and an organic solvent is added.
Examples of such organic solvents include benzene,
80 to 60 parts of an aromatic hydrocarbon such as toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, etc., and methanol, ethanol, n-propanol, iso-propanol,
It is preferable to use a mixed solvent containing 20 to 40 parts of an aliphatic alcohol such as n-butanol, iso-butanol, or n-amyl alcohol. Although the modified epoxy resin cannot be dissolved homogeneously using an aromatic hydrocarbon or an aliphatic alcohol alone, it can be homogeneously dissolved using a mixed solvent within the above composition range.

In the case of an active product using a phenoxy resin, in addition to the above-mentioned mixed solvent, ketones such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, and methyl-n-butyl ketone, and acetals such as dioxane, furfural, and tetrahydrofuran are used. It is also possible to use various solvents such as.

On the other hand, in the case of active substances using PVF, they are initially dissolved homogeneously in dioxane, tetrahydrofuran, etc., which are known to be good solvents for the polymer, but PVF precipitates within a few hours to several days, causing the solution to dissolve. cannot be used because it has no fluidity and appears to be in a gelled state. Furthermore, since the resin composition of the present invention volatilizes the solvent when producing the prepreg, it is necessary to use an inexpensive solvent. In terms of cost, the above-mentioned combination system of aromatic hydrocarbon and aliphatic alcohol is preferable because it can be obtained relatively inexpensively.

The resin composition obtained as described above further contains a compound that generates a Lewis acid upon irradiation with light.

The compound that generates a Lewis acid when irradiated with light is used to photopolymerize the remaining epoxy group of the modified epoxy resin, but it is preferably one that is easily decomposed by irradiation with light, and preferably an onium salt of a Lewis acid. used. Typical examples of such onium salts include diazonium salts and compounds containing elements of group b, group b, group b, and group b of the periodic table. Specific examples of such compounds include 4,4'-dimethyldiphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate.

However, in the present invention, when light irradiation is performed using a diazonium salt of a Lewis acid,
The diazonium group photodecomposes to generate nitrogen gas, which is undesirable because it may cause foaming or voids when the resin is cured. Considering this and the photo-curing ability of onium salts (other than diazonium salts) of Lewis acids, aromatic iodonium cations, , at least one of aromatic sulfonium cations, aromatic phosphonium cations, and aromatic ammonium cations, and BF ₄ ^- , PF ₆ ^- ,
Examples include salts with at least one of the anions represented by SbF ₆ ^- , FeCl ₄ ^2- , SnCl ₆ ^- and SbCl ₆ ^- .

In addition, the blending ratio of the onium salt of Lewis acid is 0.5 to 5 phr to the modified epoxy resin.
The range is preferably less than 0.5 phr, which is undesirable because the photocurability of the modified epoxy resin decreases.
When the amount is more than 5 phr, the light transmittance of the resin composition decreases and the internal curability deteriorates, and it is also uneconomical. In addition, in order to improve impregnation and coating workability of the resin during prepreg production, it may be diluted with an appropriate mixed solvent.

The prepreg is produced by coating and impregnating the resin composition on glass cloth, glass tape, treated cloth chemically treated with a surface treatment agent such as acrylic silane, epoxy silane, amino silane, nonwoven fabric, roving yarn, etc. This is done by evaporating the solvent in an oven.

The prepreg thus obtained can be cured by light irradiation, and a cured product with excellent properties can be obtained. In this case, the light source used can be one that effectively generates ultraviolet rays, such as a low-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, or sunlight.

Next, the composition of the present invention will be explained with reference to Examples.

Example 1 Epicoat 828 was placed in a four-necked flask equipped with a stirrer, thermometer, gas inlet, and reflux device.
Add 95 g of epoxy resin (manufactured by Ciel Chemical Co., Ltd., molecular weight 380, epoxy equivalent approximately 190) and heat to 100 to 130°C.
Add 27g of the product (type, molecular weight approx. 43000) in portions and dissolve. The contents were then heated to 180-200°C and stirred for 3 hours under a nitrogen gas stream to obtain a modified epoxy resin. Next, the temperature of this content was set to about 90
The temperature was lowered to ℃, and 169 g of toluene/n-propanol (mixed weight ratio: 70/30) was gradually added as an organic solvent to homogeneously dissolve, and then 1.2 g of 4,4'-dimethyldiphenyliodonium hexafluorophosphate was dissolved. g was blended to obtain a prepreg resin, which was designated as prepreg resin 1.

Example 2 The amount of PVF was 14g, and the organic solvent was toluene/n-butanol (mixed weight ratio: 70/30).
A prepreg resin was prepared in the same manner as in Example 1, except that 92 g was used, and 1.2 g of triphenylsulfonium hexafluorophosphate was blended in place of 4,4'-dimethyldiphenyliodonium hexafluorophosphate. This was designated as prepreg resin 2.

Example 3 Epicoat was added to a four-necked flask similar to Example 1.
95 g of 828 and 77 g of a phenoxy resin methyl ethyl ketone solution (manufactured by Toto Kasei Co., Ltd., solid content 35%) were mixed, and the temperature was increased while increasing the nitrogen airflow to distill the methyl ethyl ketone out of the system. A prepreg resin was prepared in the same manner as in Example 1, except that the contents were kept at 190±5° C. for 3 hours and a modified epoxy resin was obtained, and this was designated as Prepreg Resin 3.

Test Example 1 Prepregs were produced using prepreg resins 1 to 3 obtained in Examples 1 to 3. In other words, each resin was placed in a stainless steel dish, a plain-woven glass tape with a width of 3.8 cm and a thickness of 1.9 mm was introduced into the dish, and the tape was impregnated with the resin. The resin was applied to the tape while being squeezed between rotors, and the tape was impregnated. I let it happen. At that time, the pressure of the ironing rod was adjusted so that the amount of resin deposited was around 30% by weight. This resin-impregnated tape has approx.
After air drying for 30 minutes, the solvent was completely evaporated in a hot air circulation oven at 80°C. The tape thus obtained was a prepreg tape with no stickiness and a supple appearance, and could be easily wound around articles. When the prepreg tapes were irradiated with light for 30 seconds at a position approximately 10 cm below an ultraviolet irradiation device (one high-pressure mercury lamp of 80 W/cm, 2.5 kW), all cured products had excellent properties. An alignment tape was also prepared using roving yarn as the glass base material, and the resulting prepreg similarly maintained good workability and had excellent photocurability.

Comparative Example 1 A prepreg tape was prepared in the same manner as in Test Example 1 using a resin composition in which BF ₃ complex salt of monoethylamine was blended in place of 4,4'-dimethyldiphenyliodonium hexafluorophosphate in Example 1. was created. The prepreg tape
When heating was carried out at 160°C until the cured product had the same characteristics as the cured product of Test Example 1, it took at least 4 hours.

From the above, it can be said that when a prepreg is produced using the composition of the present invention, it is effective in terms of shortening working time and saving energy.

Comparative Example 2 (Thermosetting solvent-free varnish) 100 g of Epicote 828 and 10 g of phenoxy resin (manufactured by Union Carbide) were placed in a flask similar to that used in Example 1, and the temperature was gradually raised.
The mixture was heated at 150°C for 2 hours to dissolve it. After confirming that the phenoxy resin was homogeneously dissolved, the temperature was lowered and the temperature was reduced to approx.
When the temperature reached 50°C, 80 g of methyltetrahydrophthalic anhydride (manufactured by Hitachi Chemical Co., Ltd., trade name HN-2200) as an acid anhydride curing agent and 1 g of cobalt octylate as a latent epoxy resin catalyst were added. was added to prepare a thermosetting solvent-free varnish.

An attempt was made to produce a prepreg using the varnish in the same manner as in Test Example 1, but a tack-free B-stage prepreg could not be obtained, and only one with a sticky surface was obtained.

Comparative Example 3 (Photocurable solvent-free varnish) 100g of Epicote 828 was added with 4,
A photocurable solvent-free varnish was prepared by blending 2 g of 4'-dimethyldiphenyliodonium hexafluorophosphate.

An attempt was made to prepare a prepreg using the varnish in the same manner as in Test Example 1, but a tack-free B-stage prepreg could not be obtained, and only a sticky surface was obtained.

Comparative Example 4 (A system in which a photosensitizer is blended into a thermosetting varnish) 1.2% of 4,4'-dimethyldiphenyliodonium hexafluorophosphate was added to the resin composition prepared in Comparative Example 1 as a photosensitizer. A photosensitizer-containing varnish containing g was prepared.

When a prepreg was produced using the varnish in the same manner as in Test Example 1, a good B-stage prepreg was obtained.

However, when this prepreg was irradiated with light in the same manner as in Test Example 1, it was hardly cured and remained in the same B-stage state as the prepreg.

When the prepreg (tape) after being irradiated with light was immersed in methyl ethyl ketone, the resin content was eluted. This is probably because the thermosetting catalyst and the photosensitizer interacted and the sensitizer became inactive.

Comparative Example 5 (Blend system of thermosetting solvent-free varnish and photocurable solvent-free varnish) A blended varnish obtained by mixing 100 g of the varnish obtained in Comparative Example 2 and 100 g of the varnish obtained in Comparative Example 3 was used. Prepared.

An attempt was made to produce a prepreg using the varnish in the same manner as in Test Example 1, but a good non-stick prepreg could not be obtained, and the varnish was A-stage.
It was extremely sticky and difficult to handle.

In order to confirm the photocurability of this sticky prepreg (tape), it was irradiated with light in the same manner as in Test Example 1, but a completely cured hard composite material could not be obtained. It was something that could be eluted.

Claims (1)

[Claims] 1. For 90 to 60 parts by weight of an epoxy resin having at least two or more epoxy groups in the molecule, 10 to 40 parts by weight of polyvinyl formal, phenoxy resin, or a mixed polymer of both are added at 150 to 230°C. A photocurable prepreg resin composition comprising a modified epoxy resin obtained by reacting at temperature, an organic solvent, and a compound that generates a Lewis acid when irradiated with light. 2. The composition according to claim 1, wherein the organic solvent comprises 80 to 60 parts by weight of an aromatic hydrocarbon and 20 to 40 parts by weight of an aliphatic alcohol. 3. The composition according to claim 1 or 2, wherein the compound that generates a Lewis acid upon irradiation with light is an onium salt of a Lewis acid, and is used in an amount of 0.5 to 5 phr relative to the modified epoxy resin. 4 The onium salt of the Lewis acid contains at least one of an aromatic iodonium cation, an aromatic sulfonium cation, and an aromatic ammonium cation, and BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , FeCl ₄ ²⁻ ,
The composition according to claim 3, which is a salt with at least one of the anions represented by SnCl ₆ ^- and SbCl ₆ ^- .