JPS59230068A - Novel epoxy resin composition for powder coating compound - Google Patents

Abstract

PURPOSE:The titled composition having improved impact resistance, flexibility, and corrosion resistance, not losing impact absorbing power even at low temperature, obtained by adding a specific amount of specified epoxy modified rubber to an epoxy resin. CONSTITUTION:The desired composition consisting of (A) 97-65pts.wt. epoxy resin containing two or more epoxy groups in the molecule, having 400-2,500 epoxy equivalent, and (B) 3-35pts.wt. calculated as rubber component of epoxy modified rubber prepared by grafting (ii) a polymerizable epoxy compound and/ or monoethylene glycidyl ester or ether having >=0.5 epoxy group and 0.1-1.0 acryloyl group in one molecule, and (iii) an ethylenic monomer onto (i) base layer rubber particles having >=50wt% gel content insoluble in toluene.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel epoxy resin composition, and more particularly to a powder epoxy resin composition that has excellent needle side impact properties, readability, and corrosion resistance, and does not lose its impact absorption ability even at low temperatures. It is something.

Due to its excellent performance, epoxy resins are used in applications such as paints, electricity, civil engineering and construction, and adhesives, but are particularly often used in paints. In paint applications, the demand for powder paints is gradually increasing due to the increasing need for low pollution and resource conservation in recent years. However, since the cured product lacks flexibility and impact resistance, it is susceptible to mechanical shock and thermal shock and has various limitations in its use.

In order to compensate for these drawbacks, various rubber-modified epoxy resins have been studied, and typical examples include getadiene low polymers containing terminal carboxyl groups and epoxy resins that improve flexibility by curing them. method (e.g., Shikosho No. 30-3100), a method in which a prepolymer obtained by reacting a butadiene low polymer containing a terminal hydroxyl group with an acid anhydride is used as a curing agent for an epoxy resin to improve flexibility. (for example, JP-A No. 7-36299), or an improvement method using a rubber-modified epoxy resin obtained by reacting a butadiene-acrylonitrile copolymer rubber having one amino group at the end of the molecule with an epoxy resin (JP-A No. 7-36299).
4'97/? No.) has been disclosed. In the case of these rubber-modified epoxy resins, the rubber part undergoes phase separation during heat curing and forms a sea-island structure, which provides impact energy absorption ability and also attempts to alleviate internal stress during curing. be. However, these methods cannot obtain a uniformly cured resin due to poor compatibility with the epoxy resin, and in addition, the particle size of the rubber phase when forming this sea-island structure is controlled independently. The problem was that it was difficult to Furthermore, since the addition of uncrosslinked rubber is expected to have a rubber reinforcing effect, it is necessary to add a relatively large amount of rubber, which satisfies impact resistance and flexibility while maintaining the good physical properties inherent to epoxy resin. It was difficult to obtain a cured product with such performance.

On the other hand, ABS resin is known as a coating film with good physical properties that does not have the blocking property that is a problem with ordinary powder coatings, and it relieves internal stress by forming particles into a non-uniform coating system. , has the function of suppressing the growth of cracks that occur. However, it is well known that ABS resin has poor coating film smoothness and lacks suitability as a powder coating (I\j Kaisho! A-/'13243, etc.), and it is also known that ABS resin has poor coating film smoothness and lacks suitability as a powder coating (I\j Kaisho! A-/'13243, etc.). Even if it is expected to have a rubber reinforcing effect, the compatibility and smoothness of the coating film are poor, and it cannot be put to practical use as a powder coating.

The present inventors have improved the drawbacks of conventional cured epoxy resin products and the drawbacks of the known techniques described above, and created a composition that has excellent corrosion resistance, and satisfies flexibility and impact resistance, especially impact resistance at low temperatures. As a result of intensive studies on the method of manufacturing the same, the following invention was completed.

That is, the present invention provides an epoxy resin 9 having an epoxy equivalent weight of 1100 to 2300 and having one or more epoxy groups in the prisoner molecule.
In Parts 7 to 63, (B) base rubber particles having a toluene-insoluble gel content of 30% or more, on an average of 0.3% per molecule.
epoxy groups, at least 7 types selected from polymerizable epoxy compounds and monoethylenic glycidyl esters or ethers having an average of 0.7 to 0 acrylic groups, and an ethylenic monomer. The present invention relates to a novel epoxy resin composition for powder coatings containing 3 to 35 parts by weight of graft-modified epoxy-modified rubber as a rubber content.

The above-mentioned epoxy-modified rubber has good compatibility with epoxy resins, so if necessary, a curing agent for epoxy resins can be added to this resin composition to form a chemical bond at the interface between the rubber phase and the epoxy resin phase. Because of its presence, the strength of the cured resin is maintained in the seabird phase system. Therefore, the epoxy resin composition of the present invention has improved impact resistance and flexibility.

The present invention will be explained in more detail below.

The epoxy resin which is component (5) of the present invention is a compound having at least two epoxy resins in one molecule.

These details are explained in, for example, Monthly Polymer Processing Special Issue q "Epoxy Resin" (June 1999). A typical example thereof is a condensate of epichlorohydrin and a bisphenol compound. In this case, the bisphenol compound includes, for example, λ, 2
'-bis(+,+'-hydroxyphenyl)furopane (
Commonly known as bisphenol A), halogenated bisphenol A
, screws.

Examples include da'-hydroxyphenyl)methane (A: bisphenol F) and bis(q,q'-hydroxyphenyl)sulfone (commonly known: bisphenol S).

Preferred is bisphenol A glycidyl ether epoxy resin. It can also be used in combination with a novolac epoxy resin, a hydantoin epoxy resin, or a glycidyl ester epoxy resin. Epoxy resin has an epoxy equivalent of ￥0O-2jt00
A pulverizable solid epoxy resin is preferred. As such a powder epoxy resin, Asahi Kasei Corporation's product name AER-A&G (epoxy equivalent: 700 to 1θ00) is used.
), ABR-A&? (Epoxy equivalent/Kuta O-kotS
O) etc.

The base layer rubber particles used in component (B) have a toluene-insoluble gel content of 30 inches or more, and are made of ordinary ABS.
Conjugated /, 3-diene homopolymers used in the production of resins and such /, 3-dienes and one or more copolymerizable monoethylenically unsaturated MLfL products IFIJ, such as styrene, alpha methylstyrene, Examples include copolymers with styrene, acrylonitrile, methacrynitrile, alkyl methacrylate). The alkadiene content is related to elastic factors, especially the low-temperature shock absorption capacity of the coating.

That is, as the secondary transition temperature increases, the temperature range in which it functions as a rubber dispersion resin becomes narrower, so that the secondary transition temperature does not exceed about 0°C. Preferably, a base rubber not above about -20°C is suitable. A preferred composition of the rubber is about 7S to 100% by weight of alkadiene monomers and monovinylidene aromatic hydrocarbons (e.g. styrene) and unsaturated nitriles (e.g. acrylonitrile), or monomers selected from the group consisting of 7 or mixtures thereof. Quantity approximately 0-. 2&% by weight.

Regarding the degree of cross-linking of the base rubber particles, it is preferable that the toluene-insoluble gel content is SO or more. If it is less than SO, the rubber reinforcing effect will be poor, so a large amount of rubber is added to maintain the same impact resistance. Shinade is an aromatic compound having an average of 03 or more epoxy groups and an average of 07 to 70 acrylic groups per molecule, especially by the reaction between an aromatic epoxy resin and (ivy) acrylic acid. The resulting epoxy (meth)7 acrylate is preferred. An example of a manufacturing method is JP-A-37-10! ;'/-3 to 3 parts by weight per 100 parts by weight of the rubber described in Publication No. 7II. If the amount is less than 3 parts by weight, the compatibility with the epoxy resin will not be improved, while if it is added in an amount exceeding qo and 1 part, there will be little polymerization residue during emulsion graft polymerization, making it difficult to produce. On the other hand, monoethylenic glycidyl esters or ethers, such as glycidyl acrylate,
In the case of glycidyl methacrylate, allyl glycidyl ether, methacryl glycidyl ether, 3 to 10 f
The amount added is f1 part.

As the monofunctional monomer used for graft modification, ethylenic monomers are preferred, and acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and acrylic ff12-ethylhexyl, and the above-mentioned furkyl esters. Aromatic beer compounds such as styrene, α-methylstyrene, and beertroon; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated nitriles such as acrylonitrile and methacrylaterile; These can be used singly or in mixtures.

In the present invention, the ratio of the amount of the polymerizable epoxy compound or monoethylenic glycidyl ester or ether to the ethylenic monomer can be arbitrarily selected, but it is preferable that ethylene The proportion of the monomer is 3 to 300 parts by weight.

A preferred method for obtaining the epoxy modified rubber of the present invention is as follows: A
Pour polybutadiene or styrene-butadiene rubber latex, which is commonly used in the production of BS resin, into a reactor,
A method of obtaining by adding an emulsifier and a polymerization initiator to a mixture of at least seven types of polymerizable epoxy compounds or monoethylenic glycidyl esters and seven ethylenic monomers and carrying out emulsion polymerization at a reaction temperature of Ar0-9j°C. It is.

As the polymerization initiator, for example, peroxides, persulfates, azobis compounds, and a dox system in which these are combined with a reducing agent can be used. After a certain reaction time, when most of the monomers are essentially no longer present in the system, the polymer latex is removed and a suitable anti-aging agent is added.
It is coagulated with an inorganic salt, washed with water, dehydrated, and dried to obtain a white powdered epoxy acrylic modified rubber.

The amount of the epoxy modified rubber added is preferably adjusted to 3 to 35 parts by weight based on the epoxy resin. When the amount is less than 3 parts by weight, the degree of improvement in shock absorption ability is not significant, and when it exceeds 33 parts by weight, the coating film becomes soft and it is difficult to balance the physical properties for practical use as a powder coating.

In the present invention, the curing agent is not particularly limited. Commonly used e.g. novolak phenolic resin,
Dicyandiamide, imidazoles, hydrazides, aromatic amines, and acid anhydrides can be used.

The resin composition of the present invention contains silica, gypsum, quartz powder, calcium carbonate, kaolin, clay, mica, alumina, hydrated alumina, talc, dolomite, zircon, silicate compounds, titanium compounds, molybdenum compounds, antimony compounds, etc. Various additives such as fillers, pigments, and anti-aging agents can be blended.

In the coating film using the epoxy resin composition obtained by the present invention, epoxy-modified rubber particles by graft modification are uniformly dispersed, and the particle size and particle size distribution can be determined arbitrarily by selecting the raw material rubber latex used. can be controlled. Typically, the particle size of the graft modified rubber is
It can range in size from as small as about 0.0/micron to as large as about ho microns. Preferably, this will be in the range of about 0.10-105 depending on the desired final physical properties for a given product;
Rubber particles used in S resins can be used. Furthermore, since crosslinked rubber is used, the rubber reinforcing effect is efficiently expressed, and a small amount of addition is required compared to when uncrosslinked rubber is used. Therefore, the internal stress during curing is alleviated due to the seabird structure of the coating film, and the impact absorption ability is improved, without sacrificing the physical properties inherent to the epoxy resin. Therefore, this epoxy resin composition exhibits good flexibility and corrosion resistance, and exhibits excellent impact resistance over a wide temperature range, so it has a wide range of applications such as coating coated steel bars on the outside of steel pipes, electrical insulation, coatings, and more. It is something you have.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples unless the gist thereof is exceeded. In the examples, unless otherwise specified, parts and parts are by weight.

Example 1) Synthesis method of polymerizable epoxy compounds (a) and (b) Synthesis was carried out according to the method described in the reference example of Japanese Patent Application Laid-Open No. 1034-1034tlr. However, bisphenol A type epoxy resin AER-, which has an epoxy equivalent of 90? ,7
By using /, the modification rate of epoxy resin by methacrylic acid tOqlr (equivalent ratio) is converted into a compound (al), and the epoxy resin (equivalent ratio) is converted into a compound (al) without using a solvent.
It was subjected to graft modification as b).

2) Graft modification method using a polymerizable epoxy compound Prepare an actor with a liter tapping tube, and use polybutadiene rubber latex tJA-100/L (manufactured by Nippon Zeon Co., Ltd., solid content 1!r%, gel content ?/%) tqa
After charging t, water/, and 2 liters into a reactor and thoroughly purging with nitrogen, the temperature was raised to 30°C to form a polymerizable epoxy compound (a).
A graft monomer Tatsubinda solution consisting of J Of, butyl acrylate 2'lf, and methyl meccrylate λ&f was added over 2.3 hours. On the other hand, potassium persulfate 00 da 1, which is used as a catalyst system in the production of normal ABS resin.
, an anionic emulsifier such as Nucol F-40 (Kao Atlas Company H)/09 was dissolved in 30 y of water and added dropwise over 7 hours. That is, after the addition of the graft monomer Tatsubinda solution is completed, the reaction is completed by adding the graft monomer for another 11 hours. The graft-modified rubber latex obtained in this way has less coagulation during polymerization and is a stable emulsion.
The solid content is 3! It was r%. This was salted out by adding aluminum sulfate, for example, by a conventional method for producing ABS resin, and then washed with water, dehydrated, and dried to obtain a white powder of epoxy acrylic modified rubber. The influence of the graft modification composition was summarized in Table 1 using the same method as above using the polymerizable epoxy compound (a).

3) Manufacturing method of rubber-modified epoxy resin composition A predetermined amount of the epoxy acrylic modified rubber powder obtained in step d) was heated to 720°C.
The mixture is kneaded for 1 minute using a 3-pole heated to 100 mL, a predetermined amount of epoxy resin is added for 5 minutes, and then kneaded for 10 minutes to prepare a masterbatch. Add a predetermined amount of flow control agent (e.g. Monsanto, Modaflow) to this masterbatch.
After tri-blending the hardening agent AERHD-610 (manufactured by Asahi Kasei Corporation, modified dicyandiamide type),
After extruding with a co-kneader (manufactured by Busu Co., Ltd.) set at 90°C, the mixture is pulverized with a pulverizer to obtain a powder sample for electrostatic coating.

Examining the influence of base rubber
Containing styrene-butadiene rubber (tentative name SB-/θ) (
Particle size/300~/! ;00 people, solid content! rO%, toluene-insoluble gel content goqb)tt was used for graft modification in the same manner as above, and the physical properties of the coating film were evaluated.

D) Manufacturing method of rubber-modified epoxy resin composition powder A predetermined amount of the obtained epoxy acrylic modified rubber powder was
The mixture is kneaded for 2 minutes using three rolls heated to 0.degree. C., a predetermined amount of epoxy resin is added in S minutes, and the mixture is further kneaded for 10 minutes to prepare a masterbatch. Add a predetermined amount of flow control agent to this masterbatch (for example, Modaf ρ-
) and the hardening agent AERHD-Ato (manufactured by Asahi Kasei Corporation, modified dicyandiamide system), extruded with a co-kneader (manufactured by Busu Co., Ltd.) set at 90°C, and then crushed with a crusher and electrostatically painted. Obtain powder samples for use.

Comparative Example As a comparative example, AER-AA+P unit, ungrafted modified rubber UA-100/L, a graft product of 'UA-10θ/L made only of acrylic monomer without polymerizable epoxy compound, and product name Hiker CTBN/300 X/3
(B, F, manufactured by Gutdrich) to AER-AA
The mixture was used. In addition, Hiker CTBN /300
Since X13 is liquid at room temperature, the AER at 130℃
- AA4'P is heated and melted in advance, then the squid is made into CTBN /300X /,? were mixed and cooled to produce a masterbatch.

The results of Examples and Comparative Examples are summarized in Table 1.

The results of examining the effects on physical properties of adding 5 parts to qo parts of epoxy acrylic modified rubber to AER-44'IP are shown in Example/, λ, 3, Comparative Example/, and Co.

The results of examining the influence of the graft modification composition are shown in Example 1.
Gu,! , 6. Comparative Example t, to eliminate the influence of the base rubber,
The rubber graft-modified to 5B-10 was evaluated, and the results are shown in Example 7.

As seen in the examples in Table 1, it can be seen that all the coating films made of the resin compositions of the present invention are particularly excellent in high-speed tensile impact strength at low temperatures and DuPont impact strength. Grafted unmodified rubber or Hiker CTBN /30
It can be seen that the water absorption rate of the 0x/3 system is higher than that of the epoxy resin alone system, but it is significantly improved when the graft modified rubber is used and is not significantly different from the epoxy resin.

(Margin below)

Claims (1)

[Claims] (1>, (A) 97 epoxy equivalent epoxy resins having two or more epoxy groups in the molecule
In 63 parts by weight of N6, the content of gel insoluble in toluene is S.
The average O, S per 7 molecules of the base rubber particles is
or more epoxy groups, and an average of 0. An epoxy-modified rubber graft-modified with an ethylenic monomer and at least 111 selected from a polymerizable epoxy compound having /-IO 7 acryloyl groups and a monoethylenic glycidyl ester or ether, with a rubber content of 3 to 3 A novel epoxy resin composition for powder coatings containing 3sll parts. (2), /An epoxy compound having an average of 0.3 or more epoxy groups and an average of θ1NIO 7 acryloyl groups per molecule is an epoxy compound obtained by reacting an aromatic epoxy resin with (meth)acrylic acid ( The epoxy resin composition according to claim 1, wherein the epoxy resin composition is meth)acrylate, and the amount used is 3 to qo parts by weight based on 700 parts by weight of the base rubber particles. (3) The monoethylenic glycidyl ester is glycidyl methacrylate, and the amount used is 1/1 of the base rubber particle.
The epoxy resin composition according to claim 1, wherein the amount is 3 to 10 parts by weight based on 0.00 parts by weight.