KR20000047286A - Process for producing novolak denatured epoxy resin and powdery coating composition therefrom - Google Patents

Abstract

PURPOSE: Novolak denatured resin for steel pipe or reinforcing rod, and powdery coating composition therefrom are provided which are excellent in adhesive property for substrate, cathode spattering, and flexibility, and are able to be produced by rapid hardening(not more than 2 minutes) at low temperature(not more than 200°C). CONSTITUTION: An epoxy resin is prepared by the following steps: preparing epoxy resin containing hydroxyl group by mixing 35-45 parts by weight of phenol with 100 parts of aliphatic epoxy compounds and polymerizing thereof, wherein the equivalents of hydroxyl group is 1000-2000g/eq and the number average molecular weight is 400-1000; adding 400-440 parts by weight of bisphenol type epoxy resin and 90-230 parts by weight of phenol to 100 parts of the resultant epoxy resin to obtain polymerized bisphenol type epoxy resin, wherein epoxy equivalents is 500-2000g/eq and the number average molecular weight is 500-5000; and adding 5-30 parts by weight of novolak epoxy of which epoxy equivalents is 150-400g/eq and 1-5 parts by weight of polyphenol to obtain polymerized novolak denatured epoxy resin, wherein epoxy equivalents is 500-2000g/eq, the number average molecular weight is 500-5000, and the softening point is 90-130°C.

Description

Manufacturing method of noblock modified epoxy resin and powder coating composition using same

The present invention relates to a method for producing a noblock modified epoxy resin and a powder coating composition using the same. More particularly, a bisphenol type epoxy resin is prepared using an aliphatic epoxy compound, a bisphenol A-type epoxy resin, a curing agent and other additives, and a noblock epoxy By modifying the resin, it is possible to improve the effectiveness of the coating after coating, the adhesion to the base, the negative electrode peelability, the bar coating, the pipe coating, and other metal surface coatings. It relates to a manufacturing method and a powder coating composition using the same.

The existing epoxy resin powder coatings are prepared by containing a bisphenol A type epoxy resin and a dicyandiamide curing agent [US Patent No. 3,883,064], or a bisphenol A type epoxy resin and an acid anhydride curing agent or a hydroxypyridine curing agent. (US Pat. No. 3,819,564). However, when the dicyandiamide curing agent is used alone, it is sensitive to moisture and is not suitable for pipe coating. When an acid anhydride or hydroxypyridine curing agent is used, the fast curing or negative electrode peeling property is good, but the flexibility decreases. There is a disadvantage of poor flexibility.

In addition, a method of using a bisphenol A type epoxy resin and a noblock type epoxy resin and using a diphenol as a derivative as a curing agent has been proposed [Japanese Patent Laid-Open No. 92-20605], but the degree of crosslinking of the noblock type epoxy resin is high. There is a disadvantage in that the flexibility after coating is reduced due to the hard (hard), there is room for improvement.

In addition, a bisphenol A type epoxy resin and a method of using diphenol as a derivative as a curing agent have been proposed (US Pat. Nos. 5,686,185 and 5,077,355). It is not satisfactory enough, and in particular, there is a disadvantage in that fast curing is not performed.

In the present invention, efforts have been made to completely solve the problems of the conventional epoxy resin powder coating. As a result, the present invention is completed by preparing a powder coating by preparing an epoxy resin capable of sufficiently satisfying the coating properties through the modification of a noblock epoxy resin in order to prepare a suitable bisphenol-type epoxy resin and improve adhesion to the base and negative electrode peelability. It was.

Therefore, the present invention can be fast-cured (within 2 minutes) at low temperature (within 200 ℃), excellent adhesion to the body and the negative electrode peelability and further excellent flexibility and excellent mechanical strength such as impact, bending and coating film It is an object of the present invention to provide a method for producing a noble-block-modified epoxy resin for steel pipe and reinforcing film powder coating having excellent adhesiveness with a base, and a powder coating composition using the same.

In the manufacturing method of a noblock modified epoxy resin for powder coating,

a) A hydroxyl group having an equivalent weight of a hydroxyl group (-OH) of 1000 to 2000 g / eq and a number average molecular weight of 400 to 1000, by mixing 35 to 45 parts by weight of a polyhydric phenol with 100 parts by weight of an aliphatic epoxy compound. Preparing an epoxy resin;

b) 400 to 440 parts by weight of bisphenol-type epoxy resin and 90 to 230 parts by weight of polyhydric phenol are added to 100 parts by weight of the hydroxy-containing epoxy resin prepared above, followed by polymerization to obtain an epoxy equivalent of 500 to 2000 g / eq. Preparing a bisphenol type epoxy resin having a molecular weight of 500 to 3000;

c) To 100 parts by weight of the bisphenol-type epoxy resin prepared above, 5-30 parts by weight of a noblock-type epoxy resin having an equivalent weight of epoxy of 150 to 400 g / eq and 1 to 5 parts by weight of a polyhydric phenol are polymerized to give a softening point of 90. It is characterized by consisting of the process of manufacturing the noblock modified epoxy resin of -130 degreeC, epoxy equivalent of 500-2000 g / eq, and number average molecular weights 1000-5000.

In addition, the present invention is 50 to 65% by weight of the noblock modified epoxy resin prepared by the above production method, 10 to 20% by weight of phenol curing agent equivalent to 150 to 400 g / eq, 24 to 30% by weight of pigment and filler, and curing Another feature is an epoxy resin composition for powder coating, which contains 1 to 5% by weight of conventional additives including accelerators.

Referring to the present invention in more detail as follows.

The present invention produces a noblock modified epoxy resin that has excellent flexibility and has a suitable degree of branching, and which can be hardened (reactive) with a curing agent upon curing. A low viscosity aliphatic epoxy resin is used to give a suitable flexibility to a chain. To preferentially prepare a resin having a hydroxyl group at the terminal, and also improve reactivity by introducing a noblock epoxy having a polyfunctional group at the terminal of the main chain to improve adhesion to the base and fast curing.

When the carbon chain length of the main chain of the aliphatic epoxy compound used for the purpose of improving flexibility is too long (n is 15 or more), flexibility may be excellent, but there is a tendency for blockages during storage of the resin and paint. On the other hand, if the carbon chain of the main chain is too short, the storage performance is good, but there is a possibility that the flexibility is lowered and the flexibility is lowered. In addition, in curing rate, if the curing rate is too fast, the flexibility is lowered, if the curing rate is too slow, there is no problem in flexibility, but may not satisfy the paint properties such as mechanical strength.

Therefore, the most important point in developing a noble-block-modified epoxy resin for powder coating is that it is possible to adjust the reaction process to harmonize the raw materials and adjust the reaction property to the required physical properties so as to have proper flexibility, proper melt viscosity and proper reactivity. .

Hereinafter, a method for preparing a noblock modified epoxy resin for powder coating according to the present invention will be described in detail.

The first step is to prepare a hydroxyl group-containing epoxy resin. Hydrogen having two or more epoxy groups and having a number average molecular weight of 200 to 1000, using a liquid aliphatic epoxy compound and a polyhydric phenol at room temperature, having a number average molecular weight of 400 to 1000 and a hydroxyl group equivalent of 1000 to 2000 g / eq. The epoxy group-containing epoxy resin is prepared.

In the present invention, as the aliphatic epoxy compound, polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol Diglycidyl ether, stearyl glycidyl ether, cetyl diglycidyl ether and the like and derivatives thereof.

As the polyhydric phenol, a bisphenol type having a molecular weight of 300 to 2000 is used. Specifically, a bisphenol A type epoxy resin and a bisphenol F type epoxy resin obtained by using bisphenol A, bisphenol F or the like or by reacting epichlorohydrin are used. use. Such polyhydric phenol is used to 35 to 45 parts by weight based on 100 parts by weight of aliphatic epoxy resin. When the amount of aliphatic epoxy resin is relatively high compared to the amount of polyhydric phenol, the mechanical strength and flexibility may be improved, but the storage and reactivity may be reduced. When the amount of the aliphatic epoxy resin is used, the storage is improved. However, there is a problem that flexibility is reduced.

Curing accelerators may also be used as catalysts for reaction activation, for example quaternary ammonium, phenyltrimethylammonium chloride, tetramethylammonium, 2-methylimidazole, 2-phenylimidazole, 2-isopropylimida Sol, 2-undecylimidazole, butyltriphenylphosphonium bromide, butyltriphenylphosphate oxalate, butyltriphenylphosphonium chloride and the like can be used. The addition amount of a hardening accelerator is used in 0.05-1.0 equivalent range with respect to an epoxy compound, and is melt | dissolved in solvents, and is used.

The second process is a process for producing a bisphenol epoxy resin having an equivalent weight of 500 to 2000 g / eq and a number average molecular weight of 500 to 3000. It is prepared by reacting the hydroxy-containing epoxy resin prepared above with a bisphenol-type epoxy resin having at least one epoxy group and a polyhydric phenol.

At this time, the bisphenol-type epoxy resin used has one or more epoxy groups, has a number average molecular weight of 300 to 2000, and is liquid at room temperature, and the bisphenol-type epoxy resin is 100 wt% of the hydroxy-containing epoxy resin prepared in the first step. 400 to 440 parts by weight is used for the part. In addition, the polyhydric phenol is exemplified in the first step and uses 90 to 230 parts by weight based on 100 parts by weight of the hydroxy-containing epoxy resin. In addition, the reaction may be carried out by containing a conventional polymerization reaction additive, including the curing accelerator exemplified above.

The third process is a process for producing a noblock modified epoxy resin having a softening point of 90 to 130 ° C, an epoxy equivalent of 500 to 2000 g / eq, and a number average molecular weight of 1000 to 5000. It is prepared using a bisphenol-type epoxy resin, a noblock type epoxy resin and a polyhydric phenol prepared in the second process.

As the noblock type epoxy resin, those having an equivalent weight of epoxy of 150 to 400 g / eq and an average number of functional groups of 3 to 7 are used. For example, phenol noblock type epoxy and cresol noblock type epoxy can be used. The noblock type epoxy resin is used in an amount of 5 to 30 parts by weight based on 100 parts by weight of the bisphenol type epoxy resin prepared in the second step. When the amount of the noblock type epoxy resin is used less than 5 parts by weight, the mechanical strength and flexibility may be improved, but this may adversely affect the adhesion to the substrate and the negative electrode peelability, and may cause the solvent resistance and the chemical resistance to be lowered. In contrast, when used in excess of 30 parts by weight, the degree of crosslinking is too high, leading to deterioration in flexibility, which may lower mechanical strength and adversely affect paint properties due to the progress of the reaction during storage.

In addition, the polyhydric phenol used in the third step is 1 to 5 parts by weight based on 100 parts by weight of the hydroxy-containing epoxy resin as exemplified in the first step. In addition, the reaction may be carried out by containing a conventional polymerization reaction additive, including the curing accelerator exemplified above.

Finally, the noblock modified epoxy resin prepared through the three-step process as described above has two or more reactive groups on the backbone, has an average number of functional groups of 2 to 5 at the end of the resin, and is rapidly reactive due to rapid reactivity. The high degree of branching allows for excellent adhesion and improved flexibility to fully satisfy the paint properties of steel pipes.

In addition, the present invention includes a powder coating composition containing a noblock modified epoxy resin prepared by the above method.

The powder coating composition according to the present invention usually contains 50 to 65% by weight of a noblock modified epoxy resin, 10 to 20% by weight of a phenol curing agent having an equivalent weight of 150 to 400 g / eq, 24 to 30% by weight of a titanium dioxide as a pigment and a curing accelerator. Additives are contained, and each of these raw materials are mixed and mixed so that they can be uniformly mixed using a container mixer. The homogeneously mixed composition was melt mixed at 90-120 ° C. through an extruder of a kneader or extruder (PLK 46, BUSS), and then using a grinder, an average particle size of 30-50 μm and a particle distribution of 10-100 μm. To prepare a powder coating composition of. When the prepared powder coating composition is applied by a coating method and cured using a specimen preheated at 250 ° C., a coating film is formed.

The phenol hardener (KK450: KCC Corporation) was adjusted according to the equivalence ratio of the epoxy resin and the equivalence ratio of the hardening | curing agent. As a flow improving agent, 0.5-1.5 weight% of acryl-type (Modaflow I, Monsanto company; Fib-5, PI-201, Wally Corporation; Acronal-4F, BASF Corporation), silicone type, etc. were used. In addition, 0.1 to 0.6% by weight of organotin compounds such as imidazoles, phosphonium series, and butyl tin dilaurate were used as curing accelerators. When the curing accelerator is less than 0.1% by weight, the curing rate decreases rapidly, and 0.6% by weight or more. The storage stability is then drastically reduced and can gel during dispersion.

Pigment is used in the amount of 24 to 30% by weight, and less than 24% by weight is poor in concealment. The pigment uses titanium dioxide (TiO ₂ ), which is a white pigment, and other small amounts of organic pigment, and as a filler, barium sulfate (BaSO ₄ ), calcium carbonate (CaCO ₃ ), silica (SiO ₂ ), aluminum hydroxide (Al (OH) ₃ ) and the like can be used.

Such the present invention will be described in more detail through the following examples, but the present invention is not limited thereto.

Example 1

At room temperature, 60 g of aliphatic epoxy EX931 (epoxy equivalent 375-395 g / eq, NAGASE co.) And 24.25 g of bisphenol A (equivalent 114.5 g / eq, manufactured by Shell) were added to the flask, and 150- When the reaction is carried out at 200 ° C., when the temperature reaches 110 to 140 ° C., a hydroxy epoxy resin having an equivalent weight of 1500 g / eq, a viscosity of 7000 cps (25 ° C.) and a number average molecular weight of 400 is prepared.

100 g of bisphenol-type epoxy resin R8828 (epoxy equivalent 184 to 194 g / eq, manufactured by KCC) and 24.25 g of bisphenol A (equivalent to 114.5 g / eq, manufactured by Shell) were added to the resin thus prepared. Phosphorous butyl triphenylphosphonium chloride was injected and the reaction was heated up to about 150 to 200 ° C. to yield an epoxy equivalent of 550 to 650 g / eq. Cresol noblock type epoxy N8470 (equivalent to 205 to 225 g / eq, manufactured by KCC Corporation). 28.8 g, bisphenol A 9.5 g, and 0.061 g of triphenylphosphonyl bromide, a quaternary salt system, were added at 150 to 170 ° C as a curing catalyst and reacted while maintaining the temperature of the reactants at 150 to 200 ° C.

The finally prepared noblock modified epoxy resin had an epoxy equivalent of 785.3 g / eq, a softening point of 112.3 ° C, and a number average molecular weight of 1250.

Examples 2-6 and Comparative Examples 1-3

Following the same procedure as in Example 1 using the components shown in Table 1.

As can be seen from the above results, the powder coating prepared using the noblock modified epoxy resin according to the present invention is used for corrosion resistance and chemical resistance of a conventional epoxy resin in high temperature fast curing when used in metal surfaces, especially pipes and reinforcing bar coatings. While satisfying the general characteristics, it can be seen that flexibility, negative electrode peelability, adhesion after boiling, and the like exhibit excellent characteristics.

Claims (8)

In the manufacturing method of a noblock modified epoxy resin for powder coating, a) A hydroxyl group having an equivalent weight of a hydroxyl group (-OH) of 1000 to 2000 g / eq and a number average molecular weight of 400 to 1000, by mixing 35 to 45 parts by weight of a polyhydric phenol with 100 parts by weight of an aliphatic epoxy compound. Preparing an epoxy resin; b) 400 to 440 parts by weight of bisphenol-type epoxy resin and 90 to 230 parts by weight of polyhydric phenol are added to 100 parts by weight of the hydroxy-containing epoxy resin prepared above, followed by polymerization to obtain an epoxy equivalent of 500 to 2000 g / eq. Preparing a bisphenol type epoxy resin having a molecular weight of 500 to 3000; c) To 100 parts by weight of the bisphenol-type epoxy resin prepared above, 5-30 parts by weight of a noblock-type epoxy resin having an equivalent weight of epoxy of 150 to 400 g / eq and 1 to 5 parts by weight of a polyhydric phenol are polymerized to give a softening point of 90. It is -130 degreeC, the epoxy equivalent is 500-2000 g / eq, The number average molecular weight manufactures the noblock modified epoxy resin of 1000-5000, The manufacturing method of the noblock modified epoxy resin for powder coatings characterized by the above-mentioned. The method of claim 1, wherein the aliphatic epoxy compound has an epoxy equivalent of 100 to 500 g / eq and contains at least two epoxy groups. The method of claim 2, wherein the aliphatic epoxy compound is polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1.6 hexanediol A method for producing a noblock modified epoxy resin for powder coating, characterized in that selected from diglycidyl ether, stearyl glycidyl ether, cetyl diglycidyl ether, and derivatives thereof. The method of claim 1, wherein the noblock-type epoxy resin is a glycidyl ether of a noblock, and has an average number of functional groups of 3 to 7. The method of claim 4, wherein the noblock type epoxy resin is selected from cresol noblock type epoxy resins and phenol noblock type epoxy resins. The powder coating composition according to claim 1, wherein the bisphenol-type epoxy resin is selected from bisphenol A and bisphenol F having a molecular weight of 300 to 2000, and bisphenol A-type epoxy resin and bisphenol F-type epoxy resin obtained by reacting with epichlorohydrin. Method of producing a noblock modified epoxy resin. In a powder coating composition containing an epoxy resin as a main component and containing a conventional powder coating additive, 50 to 65% by weight of the epoxy resin prepared by the method of claim 1, 10 to 20% by weight of a phenol curing agent equivalent to 150 to 400 g / eq, 24 to 30% by weight of pigments and fillers, and curing accelerators Powder coating composition, characterized in that 1 to 5% by weight of additives. The powder coating composition according to claim 7, wherein 0.1 to 0.6% by weight of at least one selected from quaternary ammonium salts, tertiary amines, and phosphonium salts is contained as the curing accelerator.