Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-09-27
2003-05-20
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S167000, C528S169000, C528S174000, C528S487000
Reexamination Certificate
active
06566483
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel photosensitive phosphorylated phenol-formaldehyde resin and method for preparing the same. The phosphorylated phenol-formaldehyde resin is curable under UV light and soluble in alkaline solution; moreover, it exhibits good flame-retardant and adhesive properties.
2. Description of the Prior Art
Photosensitive resins have been widely used in coating materials, adhesives, printing inks, printed resin boards, printed circuit boards and semiconductors thanks to their characteristics, such as non-solvent-producing, high production efficiency due to short curing time, low investment costs due to small equipment volume needed for manufacturing, and others. Recently, the processing conditions for manufacturing circuit boards and electronic devices have gotten more strict, creating the need for a photosensitive resin with more integrated functions. The important functions concerned are flame retardancy, and good adhesion with metal or other substrates.
The flame retardant property of conventional photosensitive resin composition is generally achieved by adding halogen compounds. This method, however, has its drawbacks. Using brominated epoxy resin as an example, although there is a certain degree of flame retardancy, it produces large amounts of corrosive and toxic hydrogen bromine gas. In addition, dioxin may be generated.
Another conventional flame retardant is phosphoric compound. It has low toxicity, is less smoky, has better compatibility with resin and good workability, and requires lower dosage for use. Moreover, it improves the adhesion between resin and metals or other substrates. Its use is, therefore, an inevitable trend.
In Japanese Patent Application Laid-Open No. 9-328571, an aromatic organic phosphate compound is added to obtain a resin composition with good flame retardance, and good resistance to heat and shock.
Also, in Japanese Patent Application Laid-Open No. 2-153902, a phosphorous-containing acrylic monomer is added to an epoxy acrylate photosensitive resin composition to improve the adhesive strength of the resin.
In Japanese Patent Application Laid-Open No. 2-003454, adhesion is improved by adding a phosphate photosensitive monomer to an epoxy acrylate photocurable resin composition, which is used as a solder or plating resist in the manufacture of printed circuit boards.
In the above-mentioned patent applications, by adding phosphorous-containing photosensitive monomers to the resin composition, the viscosity of the resin is lowered, and the adhesive strength between the resin and substrate is improved. However, the phosphorous compound of a low molecular weight easily migrates and vaporizes to degrade the physical properties and flame retardancy. In addition, since the phosphorous-containing photosensitive monomer is irritating, it cannot be added in a large amount. Consequently, its application as a flame retardant is rather restricted.
The following articles relate to phosphorous-containing epoxy acrylate photosensitive resins. U.S. Pat. No. 5,512,607 discloses reacting a cresol novolak type epoxy resin with a carboxylic acid having an ethylenically unsaturated group to esterify some of the epoxy groups, and then reacting the unreacted epoxy groups with a tertiary amine as well as phosphoric acid to form a photosensitive resin containing quaternary ammonium phosphate groups. In Japanese Patent Application Laid-Open No. 7-157711, a water-soluble coating composition is prepared by reacting a phosphorylated epoxy resin with a polymerizable monocarboxylic acid having an ethylenically unsaturated bond.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a novel photosensitive phosphorylated phenol-formaldehyde resin which is curable under UV light and soluble in alkaline solutions.
Another object of the invention is to provide a photosensitive phosphorylated phenol-formaldehyde resin which is flame retardant and promotes adhesion. Thus, the environmental pollution problems caused by conventional halogenated flame retardant will be eliminated, and the adhesion between the photosensitive resin and substrate can be improved.
To achieve the above-mentioned objects, the novel photosensitive phosphorylated phenol-formaldehyde resin of the invention is characterized by having at least two phosphate groups in its molecule, and each phosphate group is coupled with at least one photosensitive group. The photosensitive phosphorylated phenol-formaldehyde resin is prepared by reacting phenol-formaldehyde resin with phosphorus oxychloride (POCl
3
) to form a phosphorylated phenol-formaldehyde resin; then reacting the resin with a photosensitive compound having an hydroxyl group and at least one ethylenically unsaturated bond to proceed dehydrochlorination, so that a photosensitive group is introduced into the resin. Finally, the unreacted phosphorochloridate group is hydrolyzed into a phosphoric group.
DETAILED DESCRIPTION OF THE INVENTION
According to the preparation method of the invention, a phenol-formaldehyde resin with repeating unit (I) and POCl
3
are reacted to form a phenol-formaldehyde resin with repeating unit (II), wherein R
1
represents C
1-6
alkylene or C
6-10
alicyclic ring; and R
2
represents hydrogen or methyl.
The reaction ratio between POCl
3
and the phenol-formaldehyde resin is not specifically restricted. However, it is preferable to set the ratio of moles of POCl
3
to the phenol equivalent of the phenol-formaldehyde resin at 0.5-1.3.
Moreover, the phenol-formaldehyde resin used in this invention is not specifically limited, as long as it can be phosphorylated by POCl
3
. Examples of the phenol-formaldehyde resins are: phenol series phenol-formaldehyde resin, formaldehyde series phenol-formaldehyde resin and alicyclic series phenol-formaldehyde resin.
Next, the phosphorylated phenol-formaldehyde resin with repeating unit (II) is reacted with a photosensitive compound (III) having an hydroxyl group and at least one ethylenically unsaturated bond in its molecule to proceed dehydrochlorination. Thereby, a phosphate group having an ethylenically unsaturated bond is coupled to the phenol-formaldehyde resin as shown in formula (IV),
wherein, R
1
and R
2
have the meaning described above; R
3
is C
2-6
straight-chain or branched alkylene and optionally substituted with heteroatoms or aryl groups; Y is a functional group having an ethylenically unsaturated bond; and x is 0 or 1.
The reaction ratio between the photosensitive compound (III) and the phenol-formaldehyde resin (with repeating unit (I)) is not specifically restricted. However, it is preferable to set the ratio of moles of photosensitive compound (III) to the phenol equivalent of the phenol-formaldehyde resin at 0.5-1.5.
The photosensitive compound (III) used in this invention is not limited, as long as it contains an hydroxyl group and at least one ethylenically unsaturated bond in its molecule. For example, the photosensitive compound can be a compound containing an hydroxyl group and at least one acrylate group in each molecule, or a compound containing an hydroxyl group and at least one methacrylate group in its molecule. Preferable photosensitive compounds include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.
Finally, the unreacted phosphorochloridate groups in the above phenol-formaldehyde system are hydrolyzed into phosphoric groups to obtain the phosphorylated phenol-formaldehyde resin of the invention, which contains repeating unit (V):
wherein, R
1
, is C
1-6
alkylene or C
6-10
alicyclic ring; R
2
is hydrogen or methyl; R
3
is C
2-6
straight-chain or branched alkylene and optionally substituted with heteroatoms or aryl groups; Y is a functional group having an ethylenically unsaturated bond; and x is 0 or 1.
In addition, the reactant system may contain a phenol-formaldehyde resin with repeating unit (I) and a phosphorylated phenol-formaldehyde resin wit
Chang Shinn-Jen
Chen Jiun-Ji
Cho Ching-Sheng
Teng Wan-Jung
Industrial Technology Research Institute
Sughrue & Mion, PLLC
Truong Duc
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