JPS5837342B2 - Netsukokaseifunmatsujiyotoriyosobutsu - Google Patents

Description

[Detailed description of the invention] The present invention relates to thermosetting powder coating compositions.

Currently, epoxy resins and vinyl chloride resins are mainly used as resins in powder coating compositions, but epoxy resin powder coatings cannot be used outdoors due to their poor weather resistance. Also, vinyl chloride resin powder coatings are thermoplastic and have poor solvent resistance and heat resistance, which limits their uses.

Recently, in order to overcome these problems, many powdered acrylic resin compositions containing glycidyl groups as functional groups have been proposed.

These acrylic resin-based powder coating compositions containing glycidyl groups as functional groups have a good balance between the thermal fluidity, crosslinking reaction rate, and softening point of the resin, resulting in a smooth coating film with excellent solvent resistance. Efforts have been made to obtain powder paints that have a good shape and have good locking resistance (a property in which the phenomenon of fusion between powder particles during paint storage is unlikely to occur).

However, conventional thermosetting acrylic resin powder coatings
As with normal solvent-based paints, it is necessary to be able to apply a thin film of about 25 to 50 μm, but the melt viscosity during the coating film formation process is high, resulting in poor flowability when the paint is heated and melted, making it difficult to apply a thin film. is difficult to obtain.

In order to obtain a thin film with this paint, there is a method of lowering the curability and improving the thermal fluidity when melted, but this is not preferable as it deteriorates the film performance such as physical properties and solvent resistance.
On the other hand, it is also possible to make the film thinner by lowering the softening point and lowering the melt viscosity, but this is not preferable because it has the disadvantage that the powders fuse together during storage, which causes a defect in blocking resistance. .

In view of these points, we conducted extensive research and found that tris(2-hydroxyethyl) insiaslate contains benzoic acid or its alkyl derivatives, aromatic, aliphatic or Alicyclic dicarboxylic acids (and (
By using a graft copolymer obtained by grafting a polycondensation adduct having one double bond at one end obtained by blending glycidyl meth)acrylate onto an acrylic resin, the above-mentioned conventional drawbacks are solved at once. He discovered what he could do and completed the invention.

That is, the present invention provides (3) (a) 1 mole of tris(2-hydroxyethyl)isocyanurate to 1.5 to 2.2 moles of benzoic acid or alkyl (C1-C4) benzoic acid, aromatic, aliphatic or aliphatic. A polycondensation adduct having one double bond at one end obtained by blending 0.8 to 1.5 moles of a cyclic dicarboxylic acid and 0.8 to 1.5 moles of glycidyl acrylate or glycidyl meccrylate. 30% by weight, (b)
Alkyl of acrylic acid or methacrylic acid (C1-C12
) 20 to 60% by weight of ester and (C) 5 to 40% by weight of glycidyl acrylate or glycidyl methacrylate.
, if necessary, (d) a graft copolymer having a softening point of 80 to 120° C. and a number average molecular weight of 2,000 to 30,000 obtained by copolymerizing a compound containing an unsaturated group-containing monomer such as styrene, a styrene derivative, or acrylonitrile. Polymer and (B) aromatic, aliphatic or alicyclic polybasic acid or anhydride thereof per mol of glycidyl group of (A), (B)
) is blended in a ratio of 0.6 to 1.2 moles of carboxyl groups.

Advantages of the present invention include (1) the unique tris(2-hydroxyethyl)isocyanurate (THE
By using a grafted acrylic copolymer of polycondensate (hereinafter referred to as Sake) of IC (hereinafter referred to as Sake), it can be used for electrostatic coating or fluid dip coating without fusion even under harsh operating conditions of 30 to 40°C. It is possible to maintain a fine powder form that can be coated with powder, and a smooth and glossy coating film can be obtained.

What should be noted here is that this Sacred Adduct is 5 to 3
If the amount of 0% grafting is too high, the softening point of the resulting grafted resin will increase, while the melt viscosity upon heating will decrease.

This violates the conventional common sense that increasing the softening point increases the melt viscosity, and is a major feature of the present invention.

Since the softening point is raised, the paint is less likely to fuse during storage and during painting, and has excellent blocking resistance and painting workability.

On the other hand, since the melt viscosity during the coating film formation process is low, a coating film with good thermal fluidity and excellent smoothness can be obtained.

(2) The mechanical strength of the coating film, that is, the impact resistance and Erichsen resistance, comparable to that of epoxy resin powder paints can be obtained, but the weather resistance, solvent resistance, heat resistance, etc. of conventional thermosetting acrylics can be obtained. It is in no way inferior to resin-based powder paints.

In addition, since the melt viscosity during the coating film formation process is low and the thermal fluidity is good, coatings as thin as 25 to 50μ can be applied without reducing curing properties, making it possible to obtain smooth and glossy coatings. .

That is, these numerous advantages of the present invention are solely due to the grafting of the aforementioned sacrificial adduct onto the acrylic copolymer.

The graft copolymer (4) that can be used in the present invention is (a):
Components (b) and (C), if necessary, can be obtained by copolymerizing a certain amount of (d).

First, component (a), Sake Adduct, is made of 1 mol of tris(2hydroxyethyl)isocyanurate and 1 mol of benzoic acids.
．． Glycidyl (meth)acrylate 08-1 to an intermediate having a carboxyl group at the terminal obtained by condensing 5 to 2.2 mol and 0.8 to 1.5 mol of aromatic, aliphatic or alicyclic dicarboxylic acids. This is a compound to which .5 mol has been added.

The benzoic acids used here are benzoic acid and its alkyl derivatives having 1 to 4 carbon atoms, such as benzoic acid, p
Representative examples include -methylbenzoic acid, pt-butylbenzoic acid, dimethylbenzoic acid, and the like.

Examples of aromatic, aliphatic or alicyclic dicarboxylic acids include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrachlorophthalic acid, succinic acid and their anhydrides or alkyl esters, isophthalic acid, terephthalic acid, and azelaic acid. , acyhinic acid, sebacic acid and dialkyl esters thereof.

The above-mentioned condensation reaction of benzoic acids and dicarboxylic acids is preferably carried out usually at 180 to 260°C for 4 to 16 hours.

The condensation reaction product thus obtained (hereinafter referred to as intermediate)
Catalysts used in the reaction of adding glycidyl (meth)acrylate to are tertiary amines such as trimethylamine, triethylamine, dimethylaminoethanol, and dimethyl coconut amine, and quaternary amines such as tetraethylammonium bromide and trimethylbenzylammonium chloride. Hydroquinone, paratertiary butyl ether, hydroquinone monoethyl ether, and the like can be used as polymerization inhibitors.

Next, (b) the precept is an alkyl ester of acrylic acid or methacrylic acid (the alkyl group has 1 to 12 carbon atoms), and specific examples of such esters include methyl acrylate, ethyl acrylate, probyl acrylate, and acrylic acid. n-butyl, i-butyl acrylate, t-butyl acrylate,
2-ethylhexyl acrylate, lauryl acrylate,
Cyclohexyl acrylate, 2-hydroxyethyl acrylate, hydroxyprobyl acrylate, methyl methacrylate, ethyl methacrylate, probyl methacrylate,
Examples include n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, and hydroxyprobyl methacrylate.

Component (C) is a glycidyl ester of acrylic acid or methacrylic acid.

When copolymerizing the above three parts (a) to (C), the proportion of each component is 5 to 30% by weight for (a) and 20 to 6% by weight for (b).
0% by weight, and (C) needs to be 5 to 40% by weight.

If the ratio is outside the above range, the blocking resistance of the resulting paint will be poor or the physical properties of the paint film will be poor.

In the present invention, an unsaturated group-containing monomer (component (d)) such as styrene, styrene derivative, acrylonitrile, etc. is further added to the above three components (a) to (C) as necessary, and these are copolymerized. A graft copolymer can be obtained.

Examples of the component (d) include styrene, vinyltoluene, acrylonitrile, methacrylonitrile, 12-
Examples include macromonomers having a double bond at the end, which are obtained by adding glycidyl methacrylate to a hydroxystearic acid condensate.

The blending amount of component (d) is preferably 50% by weight or less based on the total amount of the four components (a) to (d).

As a polymerization catalyst for copolymerizing the above components (a), (b), (C), and (d), azobisisobutyronitrile,
Azobisdimethylvaleronitrile, azobiscyclohexanecarbonitrile, penzoyl peroxide, t-
Butyl hydroperoxide, t-butyl peroxybenzoate, di-t-butyl peroxide, cumene hydromeroxide, dicumyl peroxide,
Lauroyl peroxide, t-butyl peroxyoctoate, etc. can be used.

The copolymerization reaction of the four components (a) to (d) is usually 80 to 18
It is carried out for 4-16 hours at 0°C.

The thus obtained graft copolymer (5) grafted with a sacrificial adduct must have a softening point of 80 to 120°C and a number average molecular weight of 2,000 to 30,000.

When the softening point and number average molecular weight are out of the above range, the blocking resistance of the powdered coating composition obtained is poor, or the flowability of the coating during coating is poor, and the surface smoothness of the coating film is reduced. I don't like it at all.

Examples of aromatic, aliphatic or alicyclic polybasic acids or their anhydrides [(B)] used as a curing agent in the present invention include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and adipic acid. , azelaic acid, sebacic acid, dodecanniic acid, fumaric acid, maleic acid, succinic acid, trimellitic acid, pyromellitic acid and their anhydrides, isophthalic acid, terephthalic acid, etc. can be used.

Further, as a curing catalyst, compounds such as tertiary amines, quaternary ammonium salts, organic tin, and titanium, such as triphenyltin chloride, dibutyltin laurate, and tetraisopropyl titanate, can be used.

In addition, in the powder coating composition of the present invention, inorganic and organic pigments, fluidity modifiers, curing catalyst antistatic agents, etc., which have been conventionally generally used in coatings, may be used as appropriate. can.

Regarding the preparation of the paint, all conventionally known methods can be used, such as a method of mixing the components by melt blending, a method of preparing the paint in a solution state, and then removing the solvent.

Next, the present invention will be explained with reference to production examples and examples.

Hereinafter, "%" simply refers to % by weight.

Production example of Saquaduct A: 5 liters equipped with a thermometer, water separator, stirrer, and backflow cooler.
783 g of tris(2-hydroxyethyl)in cyanurate (Sake), 1068 g of p-tert-butylbenzoic acid, and 90 g of toluene were placed in a reactor, heated to 240°C, and dehydrated and condensed for 3 hours. Then, condensation was carried out at 240°C for 3 hours.

Next, 453 g of toluene was added, and the resulting intermediate was a viscous liquid with a nonvolatile content of 80.5% and an acid value of 75.

2717 g of this viscous liquid was placed in a 5 liter reaction vessel equipped with a thermometer, dropping funnel, and stirrer, and 8.1 g of tetraethylammonium bromite was added as a catalyst.
Heat to ℃ and add 1g of hydroquinone at this temperature in advance.
511 g of glycidyl meccrylate dissolved in the solution was added dropwise from the dropping funnel over 1 hour.

The resulting addition reaction product had an acid value of 0.5 and a nonvolatile content of 84.
It was a 0% viscous liquid.

Production Example of Sake Adduct B-E Sac Adduct B-E was produced in the same manner as above according to the components and reaction conditions shown in Table 1.

However, in Saquaduct D, gelation occurred at the stage of adding glycidyl methacrylate.

This is thought to be caused by the presence of two or more double bonds in one molecule, and the combination of D is not suitable for adduct feeding.

Example of producing macromonomer In a 5-liter reaction vessel equipped with a thermometer, water separator, stirrer, and backflow condenser, 3000 g of 12-hydroxystearic acid was added.
, 150 g of toluene, 5 methanesulfonic acid as catalyst
g was added thereto, and a dehydration condensation reaction was carried out at 150°C for 4 hours.

1000 g of the obtained resin was charged into a 5 liter reaction vessel equipped with a thermometer, a stirrer, and a backflow condenser, and 140 g of glycidyl methacrylate, 1 part dimethyl coconut, 1.0 part hairmin were added.
,@1 Hydroquinone 0.5g and Toluene 1000g
was charged and reacted under reflux for 10 hours.

The obtained product had an acid value of 0.2, a nonvolatile content of 50.1%, and a molecular weight of 1800.

Hereinafter, this will be referred to as macromonomer M.

Production example of graft copolymer A grafted with saduct
Toluene (1,000.9 kg) charged into a fourth flask was heated to reflux temperature while blowing nitrogen gas.

A mixed solution consisting of 240 g of Sake Adduct A, 250 g of methyl methacrylate, 150 g of n-butyl methacrylate, 200 g of glycidyl meccrylate, 200 g of styrene, and 50 g of azobisisobutyroni IJ, which had been charged in advance in a dropping funnel to toluene kept at the same temperature, was added. After the dropwise addition took 3 hours, a mixed solution of 3g of azobisdimethylvaleronitrile and 30g of ethyl acetate was added dropwise at the same temperature three times every hour (
Hereinafter, the catalyst dropped in this way will be referred to as an additional catalyst.

) After maintaining the temperature at reflux for an additional 2 hours, the condenser was changed to a forward flow condenser and the temperature of the contents was gradually raised to 150° C. while allowing the solvent and unreacted monomer to flow out of the system.

30m at 170℃ after 60% of the charged solvent has flowed out.
After reducing the pressure in the system to mHg and maintaining it for 20 minutes, the contents were poured into a stainless steel pad and cooled and solidified.

The resulting resin was a solid resin with a softening point of 99°C.

Preparation Example of Graft Copolymers B to ① Graft copolymers B to ① were obtained by reacting in the same manner as above using each component shown in Table 2.

Examples 1 to 4 and Comparative Examples 1 to 7 Create a paint with the formulation shown in Table 3.

After each portion of kneading was carried out at 110°C for 30 minutes using hot rolls, the mixture was cooled and solidified, and the coarsely ground material was finely ground.
Fine powder sieved through a 150-mesh sieve is coated with a 0.0-mesh coating method using an electrostatic coating method. A test panel was prepared by applying the coating onto a 8 mm thick phosphate-treated mild steel plate and heating and curing it at 160° C. for 30 minutes.

The film thickness was 40±5μ.

The coating film test results are shown in Table 4.

As is clear from the above results, the composite materials of the present invention (Examples 1 to 4) exhibit good coating surface smoothness, gloss, coating film properties, and blocking resistance. If the amount of safe adduct in the copolymer is too large, the physical properties will deteriorate.

On the other hand, when the amount of saduct is too small as in Comparative Example 2, the anti-blocking/greasing properties are poor.

If there are many glycidyl groups in the graft copolymer as in Comparative Examples 3 or 6, or if there is a large amount of polybasic acid as a curing agent, gelation may occur during the production of the paint, and the paint may not work properly. Even if it is possible, the smoothness of the painted surface will be poor.

On the other hand, when there are few glycidyl groups in the graft copolymer as in Comparative Examples 4 and 7, or when the amount of polybasic acid as a curing agent is small, the physical properties are poor due to insufficient crosslinking.

When the amount of alkyl benzoic acid in the safe adduct is large as in Comparative Example 5, the softening point becomes high and the blocking resistance becomes very good, but the gloss becomes poor.

The test method used in the paint film test is as follows.

Test method Gloss (600 specular); JIS K, 5400, 6, 77
by.

Impact resistance: Erichsen test according to JIS K, 5400, 6, 13, 3; Blocking resistance according to JIS Z, 2247: A load of 30 g/CIil was applied to the sample, 4
The state of the sample was observed after being kept at 0±0.5°C for 120 hours.

It was considered good if the sample remained in its original state without being fused.

Softening point; nonvolatile content according to JISK, 5400, 6, 7;
Approximately 2 g of the sample was uniformly spread on a circular dish with a diameter of 7.5 CrIL, heated in a hot air dryer for 130.3 hours, and the nonvolatile content was calculated from the weight before and after heating.

Claims (1)

[Scope of Claims] 1 (A) (a) 1.5 to 2.2 mol of benzoic acid or alkyl (Cl-C4) benzoic acid, aromatic, aliphatic to 1 mol of tris(2-hydroxyethyl)isocyanurate. Or a polycondensation adduct having one double bond at one end obtained by blending 0.8 to 1.5 moles of alicyclic dicarboxylic acids and 0.8 to 1.5 moles of glycidyl acrylate or glycidyl methacrylate. 5 to 30% by weight (b) Alkyl of acrylic acid or methacrylic acid (C
1 to C1) 20 to 60% by weight of ester and (C) 5 to 40% by weight of glycidyl acrylate or glycidyl methacrylate, and if necessary, (d) Contains an unsaturated group-containing monomer such as styrene, styrene derivative, acrylonitrile, etc. A softening point of 80 to 1 obtained by copolymerizing a blend of
At 20°C, a graft copolymer having a number average molecular weight of 2,000 to 30,000 and (B) an aromatic, aliphatic or alicyclic polybasic acid or anhydride thereof per mole of glycidyl group in (A), A thermosetting powder coating composition characterized in that carboxyl groups are blended in a proportion of 0.6 to 1.2 moles.