JPS6365715B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive resin composition that rapidly cures in air and provides a cured product with excellent adhesion to metals and corrosion resistance, and high hardness. Up until now, thermosetting resins have mainly been used as coating materials for metal surfaces, but in recent years, solvent-free photo-curing resins have been used as they are considered to have practical advantages in terms of productivity, energy savings, and non-pollution. Polymer resins have started to attract attention. However, since photocurable resins generally have poor adhesion to metal surfaces, it is necessary to improve the adhesion by roughening the metal surface by physical means or by electrically or chemically treating it. This has the disadvantage that it increases the number of steps and does not produce the expected effects. On the other hand, in order to improve the affinity of the photocurable resin itself with metals, it has been proposed to add amino compounds, organic acids, organometallic compounds, etc.; However, it has the disadvantage that the effect of increasing affinity is surprisingly small, and it cannot be said to be practically satisfactory. The present inventors have overcome these drawbacks of conventional photocurable resins and provided a cured product that is highly sensitive, less susceptible to polymerization inhibition by air, and has high hardness, adhesion to metals, and corrosion resistance. As a result of extensive research in order to develop a photosensitive resin composition that retains moisture, it was discovered that this objective could be achieved by incorporating a certain type of inorganic filler and a certain type of phosphoric acid partial ester in combination. Based on this knowledge, the present invention was accomplished. Hitherto, compositions have been known in which organic phosphate esters are blended with photocurable resins having a specific composition to improve adhesion to metals and corrosion resistance. For example, urethane-modified oil-free alkyd resin into which polymerizable unsaturated bonds have been introduced, a photocurable paint (unexamined patent application publication Showa 49-
106537), a resin composition comprising an acrylic ester having a hydroxyl group at the β position and a reactive monomer, a ketone resin, and an acid phosphate having one or more unsaturated basic acid ester groups in the molecule. Photocurable resin composition (JP-A No. 51-125182), reaction product of unsaturated epoxy ester, special organic phosphate ester, and polyvalent isocyanate compound, ethylenically unsaturated monomer, and photosensitization (Japanese Patent Publication No. 54-30713), an active energy ray-curable coating composition containing an acrylic derivative having a hydroxyl group, a monohydroxyalkyl acrylate, and a phosphate ester (Japanese Patent Publication No. 52-110738) Publication No. 2), etc. have been proposed so far. However, these compositions require the use of a specific base resin, and cannot be universally applied to a wide range of resin compositions. On the other hand, it is also known to add pigments and inorganic fillers to photocurable resins in order to give them color and suitability as paints and inks. pigment,
Solder resist ink containing colored pigments, sensitizers and stabilizers (JP-A-51-131706), monomers and prepolymers with UV-sensitive double bonds, and colorless plate-like or flake-like fillers. Paints with added (Japanese Unexamined Patent Publication No. 111935/1983) have been proposed. However, these are only used alone for coloring or to improve adhesion, and when used in combination with phosphate esters, they improve adhesion and
It has not been used for the purpose of uniformly improving physical properties such as hardness and corrosion resistance. Therefore, when a combination of talc and a specific phosphoric acid partial ester as the above-mentioned inorganic filler is blended into a photocurable composition, it improves the adhesion and corrosion resistance to the metal and cures with high hardness. Being able to give something was completely unexpected. That is, in the present invention, (a) 0.1 to 5% by weight of a photopolymerization initiator, ( b)
The present invention provides a photosensitive resin composition for coating metal surfaces, characterized in that it contains 5 to 50% by weight of talc and (c) 0.1 to 5% by weight of a phosphoric acid partial ester having an unsaturated group. As the photosensitive component of the composition of the present invention, a resin component comprising a compound having an ethylenically unsaturated bond is used in combination with a photopolymerization initiator.
This resin component is mainly composed of a prepolymer having an ethylenically unsaturated bond and an ethylenically unsaturated compound having a hydroxyl group. or F type) reaction product of epoxy compound and acrylic acid or methacrylic acid, bisoxyethylated bisphenol A
diacrylate or dimethacrylate of type A (or type F), bisoxypropylenated bisphenol diacrylate or dimethacrylate of type A (or type F), reaction product of tolylene diisocyanate and 2-hydroxyethyl methacrylate, methylene diisocyanate and 2-hydroxyethyl methacrylate, reaction products of tolylene diisocyanate and tetramethylol triacrylate, reaction products of methylene diisocyanate and tetramethylol triacrylate, polyethylene glycol, tolylene diisocyanate and 2-hydroxyethyl reaction product with methacrylate, reaction product between polypropylene glycol, tolylene diisocyanate and 2-hydroxyethyl methacrylate, reaction product between polyethylene glycol, methylene diisocyanate and 2-hydroxyethyl methacrylate, polypropylene glycol and methylene diisocyanate 2- Reaction products of hydroxyethyl methacrylate, reaction products of aliphatic polyester, tolylene diisocyanate and 2-hydroxyethyl methacrylate, reaction products of aliphatic polyester, metal diisocyanate and 2-hydroxyethyl methacrylate, etc. Prepolymers and the like are used. In addition, examples of unsaturated compounds having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate,
-Hydroxybutyl methacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane triacrylate, 2-hydroxyethyl methacrylate, 2-
Hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate and their acrylates are preferred. This resin component can further contain an ethylenically unsaturated compound having no hydroxyl group, if desired, such as trimethylolpropane triacrylate,
Trimethylolpropane trimethacrylate, tetramethylolmethanetetraacrylate, tetramethylolmethanetetramethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol diacrylate, neo Pentyl glycol dimethacrylate, 1,5-pentanediol diacrylate,
1,5-pentanediol dimethacrylate,
1,6-diol diacrylate, 1,6-hexanediol dimethacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, triallyl isocyanurate,
Examples include diallyl phthalate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and tetrahydrofurfuryl methacrylate. In the present invention, favorable results can be obtained by:
As the compound having an ethylenically unsaturated bond, a mixture containing the above prepolymer and an unsaturated compound having a hydroxyl group such as 2-hydroxyethyl methacrylate is used, and the amount of the latter added is in the range of 5 to 30% by weight. This is the case if you choose within. If this amount is less than 5% by weight, no improvement in adhesion will be obtained when the phosphoric acid partial ester is added,
Moreover, if it exceeds 30% by weight, it is not preferable because it causes a decrease in chemical resistance and electrical insulation properties. Next, the photopolymerization initiator is preferably one that can be cured even in the presence of air. Examples of such photoinitiators include anthraquinone, 2-ethylanthraquinone, 1-chloroanthraquinone, 2-tert-butylanthraquinone, thioxanthone, 1-chlorothioxanthone, 2-methylthioxanthone, dibenzosuberone, benzyl dimethyl ketal. , benzoin ethyl ether, benzoin butyl ether, etc. These photopolymerization initiators are usually added in an amount of 0.1 to 5% by weight based on the photocurable composition. Further, in the composition of the present invention, it is necessary to use talc as an inorganic filler. Acidic inorganic fillers deteriorate storage stability and do not improve hardness. Furthermore, basic inorganic fillers such as calcium silicate and calcium carbonate solve this problem, but do not necessarily provide sufficient properties as a photosensitive resin composition for metal coating. For example, coating compositions that utilize photopolymerization generally inhibit polymerization on the metal surface due to the photopolymerization mechanism and harden rapidly, causing distortion in the cured coating film and inhibiting adhesion and adhesion. There are many. Therefore, it is almost impossible to obtain a coating film in which all 100 cut pieces remain in the cross-cut test (described later), which is an important indicator of adhesion and adhesion of the coating film to the base material. Ta. However, by using talc as an inorganic filler and combining it with a phosphoric acid partial ester having an unsaturated group, a cross-cut test result of 100/100, that is, a film showing perfect adhesion and adhesion can be obtained. Ta. This was apparently achieved for the first time by combining talc and a phosphoric acid partial ester. Talc as an inorganic filler is added to suppress curing shrinkage during photocuring. For that purpose, it is necessary to select the amount added within the range of 5 to 50% by weight, preferably 20 to 40% by weight. If this amount is less than 5% by weight, the effect of suppressing shrinkage will be insufficient, and if it exceeds 50% by weight, photocurable,
This will adversely affect the physical properties and adhesion of the cured coating. On the other hand, the phosphoric acid partial ester having an unsaturated group used in the present invention means one in which only a part of the trivalent ester is esterified with a compound having an unsaturated group. Examples of such partial esters include mono(2-methacryloyloxyethyl) phosphate, mono(2-acryloyloxyethyl) phosphate, di(2-methacryloyloxyethyl) phosphate, and di(2-acryloyloxyethyl phosphate). oxyethyl)
etc. can be mentioned. The amount of these phosphoric acid esters added is 0.1 to 5.
Selected within the range of weight %. If this amount is less than 0.1% by weight, the effect will be insufficient, and if it exceeds 5% by weight, the photocurability and physical properties of the cured coating will deteriorate, which is not preferable. In addition to the above-mentioned components, the photosensitive resin composition of the present invention may contain, if desired, auxiliary additives commonly used in ordinary photocurable compositions. The photosensitive resin composition of the present invention has excellent adhesion to metals and corrosion resistance, and provides a cured product with high hardness, so it is particularly suitable for forming coating films on metal surfaces. Next, the present invention will be explained in more detail with reference to Examples. In addition, the cross cut in the adhesiveness in each example is the number of 1 mm squares remaining when 100 cuts of 1 mm square are made with a knife to reach the base material, cellophane tape is pasted on top of the cut, and cellophane tape is quickly peeled off. It represents. Example 1 Phosphoric acid was added to 100 parts by weight of a resin component consisting of 40% by weight of a reaction product of a bisphenol A type epoxy compound and acrylic acid, 40% by weight of trimethylolpropane triacrylate, and 20% by weight of 2-hydroxyethyl methacrylate. A photosensitive resin composition was prepared by adding 1.0% by weight of mono(2-methacryloyloxyethyl), 2.0% by weight of 2-ethylanthraquinone as a photopolymerization initiator, and different amounts of talc, and kneading with three rolls. did. This composition was applied to a copper surface to a thickness of 20 μm, irradiated with a high-pressure mercury lamp (48 KW, 80 W/cm) from a distance of about 20 cm, and exposed to light equivalent to 150 mJ using an integrated luminometer. The results are shown in Table 1.

[Table] Example 2 Based on 100 parts by weight of a resin component consisting of 40% by weight of the reaction product of bisphenol A type epoxy compound and acrylic acid, 40% by weight of trimethylolpropane triacrylate, and 20% by weight of 2-hydroxyethyl methacrylate. , 2% by weight of 1-tert-butylanthraquinone as a photopolymerization initiator and 50% by weight of talc as an inorganic filler were added, and different amounts of mono(2-methacryloyloxyethyl) phosphate were added, and the polymerization was carried out in three rolls. A photosensitive resin composition was prepared by kneading. This material was applied to a copper surface in the same manner as in Example 1, and after curing, the physical properties of the coating film were tested. The results are shown in Table 2.

[Table] Example 3 Based on 100 parts by weight of a resin component consisting of 40% by weight of the reaction product of bisphenol A type epoxy compound and acrylic acid, 40% by weight of trimethylolpropane triacrylate, and 20% by weight of 2-hydroxyethyl methacrylate. , 2- as a photoinitiator
2% by weight of methylthioxanthone and monophosphoric acid (2% by weight)
-methacryloyloxyethyl) and 50% by weight of an inorganic filler were added, followed by kneading with three rolls to prepare a photosensitive resin composition. This composition was treated in the same manner as in Example 1,
The results obtained are shown in Table 3.

[Table] Example 4 and Comparative Examples 1 and 2 The composition used in Example 3 with a different inorganic filler was prepared and tested for stability after being stored at 40°C for 30 days. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. For a resin component consisting of a prepolymer having an ethylenically unsaturated bond, an ethylenically unsaturated compound having a hydroxyl group, and optionally an ethylenically unsaturated compound having no hydroxyl group, (a) Photopolymerization initiator 0.1-5% by weight (b) Talc 5-50% by weight (c) Phosphoric acid partial ester with unsaturated group
A photosensitive resin composition for coating metal surfaces, characterized in that it contains 0.1 to 5% by weight.