EP0663931A1

EP0663931A1 - Polymerisable curable moulding compounds and moulding or coating process using this moulding compound

Info

Publication number: EP0663931A1
Application number: EP93920845A
Authority: EP
Inventors: Yoshitami Yamamura; Nobuhiko Morimoto; Nobuyuki Tanaka
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1992-10-09
Filing date: 1993-09-30
Publication date: 1995-07-26
Also published as: CA2146745A1; WO1994009050A1; US5589230A; JPH06172471A

Abstract

The moulding compound of the invention contains (A) 100 parts by weight of an unsaturated epoxy ester resin with an acid number below 3; (B) 10 to 40 parts by weight of phenoxyethylacrylate, 2-acroyloxyethyl-2-hydroxypropylphthalate or a mixture thereof; and (C) 1 to 5 parts by weight of a mixture of hydroxy ketone oligomers and 2-hydroxy-2-methyl-1-phenylpropan-1-one; and possibly (D) 0.5 to 5 parts by weight of polystyrene microbeads. The moulding compound can easily be cured by brief uv irradiation and gentle heating. A synthetic resin is obtained with high heat and water resistance, good electrical insulating properties and low cracking and shrinkage. It is suitable for the production of electrical/electronic components.

Description

"Polymerizable curable molding compound and molding or coating process using this molding compound"

Field of the Invention

The present invention relates to a polymerizable curable molding composition which can be molded by simultaneous heating to lower temperatures and UV radiation, and a molding or coating process using this molding compound.

State of the art

Unsaturated epoxy esters made from epoxy resin and unsaturated carboxylic acid have been widely used for corrosion protection coatings or gel coatings for the GRP process because the unsaturated epoxy ester is easy to handle due to its low viscosity and can be cured at lower temperatures. the hardened ester resin being distinguished by excellent water and chemical resistance and adhesion to metals. This ester has also recently been used for coating, gluing and sealing ^" electrical / electronic components and for shaping optical data storage media, such as so-called" laser discs (laser storage disks) ", by utilizing the photo-curing property of their unsaturated bond (JP Kokai Sho 62-169643, JP Kokai Hei 1-169755).

Unsaturated epoxy esters harden quickly through UV radiation. However, this application is limited to coating, lining or shaping thin-walled bodies, because the previous unsaturated one Epoxy esters do not cross-link well in hardening thick-walled bodies. JP Kokai Hei 1-169775 teaches that epoxy vinyl ester formulated with organic peroxide is poured into a narrow gap (1.2 mm thick) from a metal plate and a transparent plastic plate and is cured by UV radiation to form the optical storage plate.

JP Kokai Hei 2-235917 and Hei 3-188102 relate to the use of a composition of epoxy acrylate and bisphenol-A epoxy resin with hardener and photochemical initiator for sealing electronic components. However, this mass has a short storage time, which results in difficulties with long-term storage.

JP Kokai Hei 3-210324 describes the use of a mixture of UV-curable, acrylic and epoxy group-containing synthetic resin and a fatty amine epoxy derivative as a casting compound for components. However, this method uses a metering mixer to mix the two components. This system therefore requires great technical effort in its industrial application.

There was therefore still the desire to provide a long-term storage-stable composition for molding, casting or coating compositions, which can be easily cured by UV radiation to form thick-walled bodies.

Object of the invention

Taking into account the above requirements, the present invention provides a curable molding composition which is long-term storage-stable, polymerizable, unsaturated epoxy ester as the main component and which can be formed by UV radiation or by simultaneous UV radiation and heating (30-50 ° C) to form a thick-walled molded or potting body (up to 50 mm thick) or a coating can be hardened. The body shaped or coated in this way shows good hardness, adhesion to metals, water resistance, excellent electrical values and low crack formation or shrinkage. These properties are desirable for electrical / electronic components as well as for auto parts.

Solution of the task

After extensive investigations, it has been shown that a special unsaturated epoxy ester containing a certain photoinitiator can be cured within a short time by simultaneous UV radiation and gentle heating to form thick-walled casting or molded bodies (up to 50 mm thick). The present invention thus lies in a process for molding or coating electrical / electronic components and auto parts using a synthetic resin composition consisting of (A) 100 parts of unsaturated epoxy esters with an acid number below 3.0 (K0H mg / g), (B) 10 - 40 parts of phenoxyethyl acrylate, 2-acroyloxyethyl-2-hydroxypropyl phthalate or a mixture thereof and (C) 1-5 parts of a mixture of hydroxyketone oligomer and 2-hydroxy-2-methyl-l-phenylpropan-l-one as photoinitiator and, if appropriate (D ) 0.5 - 5 parts polystyrene microsphere, which is characterized by simultaneous UV radiation and heating at lower temperatures.

The invention also consists in the selection of the above synthetic resin composition which contains components A to C and D, respectively.

The unsaturated epoxy resin used according to the present invention is produced in a known manner (Japanese patent publications 44-31836, 45-15988, 45-40069), namely from unsaturated carboxylic acid and epoxy compound or from one Mixture of unsaturated / saturated carboxylic acid and epoxy compound, the unsaturated epoxy ester resin being diluted with polymerizable monomer for practical use. (The diluted solution is referred to below as "unsaturated epoxy ester resin composition".)

The unsaturated epoxy ester resin according to the invention is prepared by reacting a total of less than 1.0 mol of carboxyl groups with 1.0 mol of epoxy groups, the esterification being carried out until the acid number of the reaction mixture has dropped to below 3.0 by the proportion of unreacted carboxylic acid to be kept as low as possible in the emerging synthetic resin. An acid number of more than 3.0 in the unsaturated epoxy ester resin can lead to incomplete curing during UV irradiation and give rise to poor electrical properties.

The carboxylic acid used according to the invention for the production of the unsaturated epoxy ester resin or at least part of it should be a polymerizable unsaturated carboxylic acid, such as maleic, fumaric, itaconic, acrylic or methacrylic acid. According to the invention, saturated aliphatic or aromatic acids and long-chain monovalent or polyvalent carboxylic acids can be used as part of the carboxylic acid. Suitable saturated carboxylic acids are aliphatic acids, such as butter, lauric, stearic or hydroxystearic acid. Succinic, adipic, azelaic, sebacic or hexahydrophthalic acids are suitable as polyvalent carboxylic acids. Aliphatic acids can also be useful for adjusting the oiliness of the resulting resin, which in turn can be useful for adjusting the molecular weight of the resin. Non-polymerizable or difficultly polymerizable carboxylic acids are, for example, oleic and ricinoleic acid. The acids are suitable to give the resin flexibility to lend. As aromatic carboxylic acids, phthalic, isophthalic and trimellitic acid can be used.

At least 10 equivalent%, preferably 20-95 equivalent% and in particular 40-80 equivalent%, based on the total acid, of the polymerizable unsaturated carboxylic acid mentioned above can be present. If less than 10 equivalent% of unsaturated acid are used, the curing properties of the resulting resin can be inferior. On the other hand, more than 95 equivalent% of unsaturated acid can lead to insufficiently dry coating films.

Epoxy compounds reactive with carboxylic acids include reaction products of epichlorohydrin with bisphenol A, glycols, carboxylic acids or phenol-formaldehyde condensation products, as well as oxidation products of unsaturated compounds and combinations of more than two of them. Commercial types of these epoxy compounds are Epikote (Yuka Shell Epoxy Co.), Araldite (Ciba-Geigy Japan Ltd.), D.E.R. (Dow Chem. Japan Ltd.), Epotohto (Tohto Kasei Co.) and others.

The polymerizable monomer serves to lower the viscosity of the epoxy ester and the resin composition and should be selected from those monomers which do not impair the hardenability and physical properties of the hardened resin. Such polymerizable monomers are phenoxyethyl acrylate, 2-acroyloxyethyl-2-hydroxypropyl phthalate or a mixture of one or both of them with one or more than one monomer from the following group: styrene, vinyl toluene, divinylbenzene, methyl methacrylate, methacrylonitrile, diallyl phthalate and 2-ethylhexyl acrylate. The weight ratio of diluent to unsaturated epoxy ester composition is 10-40 parts, preferably 15 - 20 parts to 100 parts. A smaller amount than 10 parts by weight of the diluent can lead to handling difficulties due to high viscosity, while more than 40 parts by weight can give rise to a delay in the curing rate and to impair the physical properties of the cured resin.

A mixture of hydroxyketone oligomer and 2-hydroxy-2-methyl-1-phenylpropan-1-one (II) is suitable as a photoinitiator. As an example of a hydroxy ketone oligomer, the oligomer of 2-hydroxy-2-methyl-l- [4- (l-methylvinyl) phenyl] propanone (I) is named.

illustration 1

A mixture of (I) and (II) (ratio = 7: 3) is commercially available under the trademark "Esacure KIP 100F-" (manufacturer: Fratelli Lamberti Co.). The photoinitiator is used in amounts of 1.0-5.0 parts by weight, preferably 2.0-3.5 parts by weight, per 100 parts by weight of unsaturated epoxy ester composition. An amount of less than 1.0 part by weight can lead to a delay in the curing rate, while more than 5.0 parts by weight can give rise to yellowing of the hardened product and to increased production costs. In order to obtain a suitable balance between the curing rate and the properties of the cured product, it is possible to use photosensitizers, such as, for example, benzophenone or tert-amines, together with the photoinitiator mentioned above. Similarly, promoters such as methyl ethyl ketone or cumene peroxide can also be used.

If necessary, additives or fillers, such as quartz powder or TiO 2 or polystyrene microsphere, can be used. In particular, the addition of a small amount of polystyrene ball can reduce the shrinkage of the hardened resin without affecting the hardening properties and keep the space between the resin and the mold wall as narrow as possible. The resulting "closely shaped" product is thus able to prevent the ingress of moisture or corrosive gases from the outside. The addition of polystyrene microsphere can also improve the thermal shock behavior of the cured resin. Such an additive is therefore favorable for electrical components that are exposed to thermal shock, especially when it comes to large formats (larger than 20 mm).

Polystyrene microspheres are made of polystyrene (diameter = 0.2 - 0.5 mm), which contains a volatile liquid that foams when heated under pressure. Such polystyrene microspheres are under the trade name "Kanepearl" from Kanegafuchi Kagaku Co. available. The polystyrene microsphere is used in amounts of 0.5-5 parts, preferably 1-3 parts, per 100 parts of unsaturated polyester. The addition of the microsphere in such quantities ensures that they are evenly distributed in the unsaturated polyester and result in an almost transparent hardened product without causing difficulties with UV radiation. Additions of more than 5 parts can impair the properties of the hardened product. With additional amounts of less than 0.5 parts, the effect is insufficient.

The radiation dose in the case of simultaneous UV irradiation and heating depends on the thickness, the amount of filler or insert used or the complexity of the molding or potting body. If a 160 W / cm metal halide mercury lamp is used, an irradiation time of 5 to 60 s should normally suffice. Thin-walled bodies can easily be cured by UV radiation at room temperature. In the case of thick-walled moldings or potting bodies containing an insert (thickness => 20 mm), the UV radiation must be accompanied by heating to 30-50 ° C. Prolonged irradiation or heating at higher temperatures may be possible.

The body shaped in this way shows little cracking and shrinkage and good adhesion to the mold wall or the insert. Since this system hardens faster at lower temperatures than the previous one under otherwise identical conditions, the molded articles are characterized by low warpage and greater productivity.

The invention is explained in more detail below using an example. example

Production of the resin

The unsaturated epoxy ester resin composition was prepared as follows:

(Sample A)

200 pbw (pbw = parts by weight) of Epikote 828 (Yuke Shell Epoxy Co.), 68 pbw of methacrylic acid, 1 pbw of benzyldimethylamine as catalyst and 0.02 pbw of hydroquinone as inhibitor were introduced into a 1000 ml three-necked flask. The reaction was carried out at 120 ° C. in the presence of air within 2 hours. After the reaction, the mixture was cooled to 100 ° C. and then 0.01 pbw of hydroquinone and 60 pbw of 2-acroyloxyethyl-2-hydroxypropyl phthalate were added to the mixture and dissolved therein uniformly. Sample A thus obtained had an acid number (K0H mg / g) of 0.49.

(Sample B)

Starting materials as for sample A. The reaction was carried out within 1 hour 40 minutes at 120 ° C. in the presence of air. After the reaction, the mixture was cooled to 100 ° C., and then 0.01 pbw of hydroquinone and 60 pbw of phenoxyethyl acrylate were added to the mixture and dissolved therein uniformly. Sample B obtained in this way had an acid number (K0H mg / g) of 1.2.

(Sample C)

200 pbw (= parts by weight) of Epikote 828, 37 pbw of azelaic acid, 51 pbw of methacrylic acid, 1 pbw of benzyldimethylamine as catalyst and 0.02 pbw of hydroquinone as inhibitor were introduced into a 1000 ml flask. The reaction was carried out at 120 ° C. in the presence of air within 2 hours. After the reaction, the mixture was cooled to 100 ° C. and then 0.01 GT hydroquinone and 60 GT 2-acroyloxyethyl-2-hydroxypropyl phthalate were added to the mixture and dissolved therein uniformly. Sample C thus obtained had an acid number (KOH mg / g) of 0.34.

(Sample D)

Starting materials as for sample C. The reaction was carried out at 120 ° C. in the presence of air within 110 minutes. After the reaction, the mixture was cooled to 100 ° C. and then 0.01 pbw of hydroquinone and 60 pbw of phenoxyethyl acrylate were added to the mixture and dissolved therein uniformly. The sample D obtained in this way had an acid number (KOH mg / g) of 1.2.

(Sample E)

Starting materials as for sample A. The reaction was carried out within 90 minutes at 120 ° C. in the presence of air. After the reaction, the mixture was cooled to 100 ° C, and then 0.01 pbw of hydroquinone and 30 pbw each of 2-acroyloxyethyl-2-hydroxypropylphthalate and phenoxyethyl acrylate were added to the mixture and dissolved therein uniformly. Sample D obtained in this way had an acid number (KOH mg / g) of 2.5.

(UV radiation test) (Example 1)

3 parts of Esacure KIP 100F (from Fratelli Lamberti), each, were added to 100 parts of samples A - E (as prepared above) and comparative samples F, G (commercially available unsaturated epoxy esters with acid numbers of 8.5 and 9.2, respectively) Mixture of hydroxyketone oligomer and 2-hydroxy-2-methyl-l-phenylpropan-l-one added. 50 g of the resulting resin masses A - G were placed in a polyethylene container (diameter = 5 cm, height = 6 cm) at 50 ° C warmed up and then 10 s. irradiated by means of a UVL-4000 M3 160 W / cm metal halide mercury lamp arranged 7 cm above the sample. The UV-irradiated samples were cooled to room temperature and then checked.

The hardness values of the samples are shown in Table 1.

Table 1 cured resin composition A B C D E F G

Hardness, Shore D 84 83 82 84 83 32 41

The hardened samples A - E showed smooth surfaces with low shrinkage. The comparative samples F and G were incompletely cured and had sticky surfaces.

(Example 2)

The cured samples A and F from Example 1 were tested for their electrical properties. The results are shown in Table 2.

Table 2

Dielectric ^strength * KV / mm volume resistance * (DC500V) ohπr ^cnι dielectric constant * (1 KHz) dielectric loss factor * volume shrinkage **%

* ASTM D-149, D-150, D-257 ** SPI method (Example 3)

After aging for 1 week at room temperature, test specimens (40 mm × 40 mm × 5 mm) were produced from sample A, example 1. They were immersed in various chemical solutions and stored therein at 40 ° C for 90 days. The test specimens were then checked; the results are listed in Table 3.

(Example 4)

To 100 parts of Sample B (prepared as above) 3 parts of polystyrene balls (Kanepearl) and 3 parts of Esacure KIP100F were added. 50 g of this resin mass were placed in a polyethylene container (diameter = 5 cm, height = 6 cm), heated to 50 ° C. and then for 10 s. irradiated by means of a UVL-4000 M3 160 W / cm metal halide mercury sheet arranged 7 cm above the sample. The UV-irradiated samples were cooled to room temperature. The resin cured in this way had a transparent and smooth surface with little cracking and shrinkage. Hardness (Shore D) = 75.

(Example 5)

A sample cured as in Example 4 was tested for its thermal shock behavior. Thermal shock test

A ring of filter paper (diameter = 1.9 cm; height = 0.54 cm) was placed in the middle of an aluminum bowl (diameter = 5 cm; height = 4 cm). Then a ring made of galvanized steel (outside diameter = 2.6 cm; inside diameter = 1.7 cm; thickness = 0.2 cm) was placed on the paper ring. The resin composition used in Example 4 was gradually poured into the aluminum shell in such a way that the resin composition had a layer height of 20 mm. After the empty space inside the galvanized steel ring and the paper ring was filled with resin, it was 10 s. irradiated with a UVL-4000 M3 160 W / cm metal halide mercury lamp arranged 7 cm above the sample. The cured samples were cooled to room temperature and left to stand for 7 days. The heat cycle test was carried out with 3 samples each in an air circulation oven for 1 hour at 0 ° C. and then for 1 hour at 80 ° C. The results are shown in Table 4.

Table 4

Cycle 1 2 3 4 5 6 7 8 9 10 sample

1 0 0 0 0 0 0 0 0 1 1

2 0 0 0 2 1

Sample 1: prepared according to Example 5.

Sample 2: Sample A from Example 1 was mixed with the photoinitiator. The resin composition was then exposed to UV radiation as in Example 5.

The numbers in Table 4 correspond to the numbers of the cracks. (Application example) (example 6)

A housing (a) made of phenolic resin, which had small depressions (10 mm × 10 mm × 10 mm) on its upper side, contains electrical connecting terminals (d) in each recess. As shown in Fig. 2, electrical wires (b, insulated) were connected to each terminal by small screws (c).

EF.SÄ7ZELATT a: Housing (phenolic resin) b: Electrical wire (insulated with PVC) c: Screw (copper) d: Terminal block (copper)

A resin composition from sample A (3 parts per 100 parts resin composition) mixed with Esacure KIP 100 F was heated to 30 ° C. and, after the electrical line had been connected, poured into each recess in the housing. The cast resin composition was then irradiated for 10 s using a UVL-4000 M3 160 W / cm metal halide mercury lamp arranged 10 cm above the wells. After the irradiation, the resin composition was well cured, and both the connecting terminal and the wire were cured with hardened resin without cracking and shrinking. The cured resin composition showed good heat resistance at 150 ° C.

(Example 7)

A housing (a) made of phenolic resin, which had small indentations (length: 20 mm, width: 20 mm, depth: 10 mm) on its top, contains electrical connecting terminals (d) in each indentation. As shown in Fig. 2, insulated electrical wires (b) were connected to each terminal by small screws (c). The resin composition according to Example 4 was preheated to 30 ° C. and, after the electrical line had been connected, poured into each recess in the housing. The cast resin mass was then irradiated as in Example 6 for 10 s using a UVL-4000 M3 16C W / cm metal halide mercury lamp. After the irradiation, the resin composition was well cured, both the connecting terminal and the wire having cured resin being adequately sealed without cracking and shrinkage. (Example 8)

A deflection yoke coil (diameter = 18 cm) for cathode ray tubes was coated with the resin composition in order to tension the coil. To 100 parts of the resin composition of Sample A, 0.1 part of colloidal silica and 3 parts of Esacure KIP 100F were added to form a thixotropic mixture. The yoke coil was immersed in the mixture thus formed and then removed so that about 50 g of the mixture were distributed on the surface of the coil. The coated yoke coil was then irradiated for 10 seconds at 25 ° C. by means of a UVL-4000 M3 160 W / cm metal halide mercury lamp arranged 10 cm above the coil. After the UV radiation, the coated coil was stretched with resin to prevent fraying. The coated coil shows good heat resistance and does not soften even at 140 ° C.

Effect of the invention

The resin composition according to the invention is cured well by short-term UV radiation and gentle heating and forms a hard synthetic resin with high heat and water resistance, good electrical insulation, and low cracking and shrinkage. The resin composition is therefore suitable for molding, casting and coating electrical / electronic components and auto parts.

Claims

1. Polymerizable curable molding composition containing (A) 100 parts by weight of an unsaturated epoxy ester resin with an acid number below 3.0, (B) 10 - 40 parts by weight of phenoxyethyl acrylate, 2-acroyloxyethyl-2-hydroxypropyl phthalate or a mixture thereof and (C) 1 - 5 parts by weight of a mixture of hydroxyketone oligomer and 2-hydroxy-2-methyl-l-phenylpropan-l-one and optionally (D) 0.5 to 5 parts by weight of polystyrene microspheres.

2. Molding process using the polymerizable curable molding composition according to claim 1, characterized by simultaneous UV radiation and heating.

3. Coating method using the polymerizable curable molding composition according to claim 1, characterized by simultaneous UV radiation and heating.