JPH11116853A - Polyester resin composition for antibacterial and antifungal powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain at low cost a polyester resin composition capable of giving favorable coating film of excellent antibacterial/antifungal effect, by incorporating a polyester resin with a biguanide compound as antibacterial/antifungal agent. SOLUTION: This composition is obtained by incorporating a polyester resin for powder coating use 0.15-0.40 dL/g in intrinsic viscosity with 0.1-15 wt.%, based on the polyester resin, of a biguanide compound (e.g. chlorhexidine hydrochloride) [pref. by incorporating a polyester resin 15-85 mgKOH/g in hydroxyl number, bearing hydroxyl groups as the main terminal groups, with the biguanide compound followed by kneading the blend by the use of a kneader].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyester resin composition for powder coatings having excellent antibacterial and antifungal properties.

[0002]

2. Description of the Related Art In houses, hospitals, office buildings, factories, and the like, products made of materials such as metals and ceramics are coated for protection and decoration. In recent years, problems have arisen in that the painted surface is contaminated by propagation of fungi and the like, which impairs aesthetic appearance and is unfavorable for hygiene. Therefore, a solvent-type paint to which an antibacterial and antifungal agent is added has appeared. However, environmental pollution due to organic solvents and the like has also become a serious problem, and water-based paints and high-solid paints have come to be used. Thus, antibacterial and antifungal paints have been added to water-based paints, but these water-based paints and high-solids paints require organic solvents, albeit in small amounts, and are not preferable in terms of environmental pollution. Was.

[0003] On the other hand, powder coatings are non-polluting coatings, can be used immediately after coating, do not require multiple layers of coating, and are relatively inexpensive compared to conventional solvent-based coatings. In addition, the advantages of being able to recover and reuse the surplus during painting are recognized, and in recent years the demand has rapidly increased as a protective decorative paint for components such as building materials, home appliances and automobile parts. ing.

In the field of powder coatings, as coatings having antibacterial and antifungal properties, resin compositions for antibacterial powder coatings comprising a specific zirconium phosphate and a resin for powder coatings (Japanese Patent Application Laid-Open No. Hei 6 (1994)).
No. 25561) and polyester resin compositions for antibacterial and antifungal powder coatings containing zeolite solid particles carrying a metal exhibiting antibacterial properties (JP-A-8-60036). There was a problem that the product was colored and the antibacterial effect was not sufficient.

[0005]

The object of the present invention is to provide a polyester resin composition for powder coatings which can be produced at low cost, has excellent antibacterial and antifungal properties and gives a good coating film. Is what you do.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by blending a biguanide compound as an antibacterial agent and an antifungal agent into a polyester resin for powder coating, the antibacterial and antibacterial effects have been improved. The inventors have found that a polyester resin composition for powder coatings having antifungal properties can be obtained, and have completed the present invention.

That is, the present invention has an intrinsic viscosity of 0.15 to 0.1.
The gist is a polyester resin composition for antibacterial and antifungal powder coating, characterized in that a biguanide compound is added to the polyester resin for powder coating at 40 dl / g in an amount of 0.1 to 15% by weight based on the polyester resin. Things.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, the polyester resin for powder coating must have an intrinsic viscosity of 0.15 to 0.40 dl / g. When the intrinsic viscosity is less than 0.15 dl / g, the composition has poor blocking resistance. On the other hand, when the intrinsic viscosity exceeds 0.40 dl / g, crushability is poor. Particularly preferred are those having an intrinsic viscosity of 0.20 to 0.35 dl / g.

[0010] Furthermore, since it is for powder coatings, it has a softening point.
Those in the range of 50 to 150 ° C are preferred. If the softening point is less than 50 ° C., the powdered resin tends to aggregate and solidify, and the blocking resistance tends to be poor. On the other hand, softening point is 150 ℃
If the temperature exceeds the temperature, the kneading temperature must be increased, and a part of the reaction with the curing agent has already progressed during the melt kneading, and as a result, the smoothness and strength of the coating film tend to decrease.

The polyester resin for powder coating includes a polyester resin having a hydroxyl group at the main terminal and a polyester resin having a carboxyl group. In the present invention, any type can be used.

In the case of a polyester resin having a hydroxyl group at the main terminal, it is preferable that the hydroxyl value is 15 to 85 mgKOH / g. When the hydroxyl value is less than 15 mgKOH / g, large irregularities are generated on the surface of the coating film, and the smoothness is reduced. On the other hand, if the hydroxyl value exceeds 85 mgKOH / g, not only does the strength of the coating film decrease, but if a curing agent is added so as to have a functional group amount corresponding to the hydroxyl value of the resin, the coating becomes expensive. .

In the case of a polyester resin having a carboxyl group at the main terminal, the acid value is preferably 15 to 85 mgKOH / g. When the acid value is less than 15 mgKOH / g, large irregularities are generated on the surface of the coating film, and the smoothness is reduced. On the other hand, acid value is 85mgK
If it exceeds OH / g, the strength of the coating film decreases.

Examples of the acid component of the polyester resin include dicarboxylic acids, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic anhydride; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dodecane diacid. And alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid are mainly used. A tri- or higher carboxylic acid such as trimellitic acid, pyromellitic acid or trimesic acid may be used together with the dicarboxylic acid as long as the polyester resin is not gelled.

As the alcohol component, glycols such as ethylene glycol, neopentyl glycol,
Diethylene glycol, propylene glycol, 1,4-
Butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, and the like are mainly used. A trifunctional or higher functional polyol such as trimethylolpropane, glycerin, pentaerythritol or the like may be used together with the glycol as long as the polyester is not gelled.

Further, a small amount of a hydroxycarboxylic acid such as 4-hydroxybenzoic acid or ε-caprolactone may be used in combination.

The polyester resin in the present invention can be prepared by a conventional method for producing a polyester resin for powder coatings using the above-mentioned components (including their ester-forming derivatives) as raw materials.

That is, using the above-mentioned raw materials,
After the esterification or transesterification reaction is performed at a temperature of 0 ° C, the pressure is reduced to 200-300 ° C, preferably 2
It can be prepared by performing a polycondensation reaction at a temperature of 30 to 290 ° C. to obtain a polyester having a high degree of polymerization, and depolymerizing using a polyhydric alcohol or a polycarboxylic acid.

After the esterification or transesterification reaction is carried out by a conventional method, the pressure is reduced under a reduced pressure of about 50 to 100 hPa.
It can also be prepared by conducting a polycondensation reaction at a temperature of from about 300 ° C., preferably from 220 to 280 ° C., until a predetermined intrinsic viscosity is reached.

For the esterification or transesterification reaction and the polycondensation reaction, known catalysts can be used.

In the present invention, a biguanide compound is blended with the above polyester resin for powder coating as an antibacterial and antifungal agent. Powder coatings have a process of mixing and kneading hardeners and various additives in the manufacturing process, and baking after painting, so the antibacterial and antifungal agents used must have heat resistance of about 200 ° C or more. In addition, it is necessary that the polyester resin has good kneadability with the polyester resin, is easily and uniformly dispersed, does not discolor under heating, and does not color the polyester resin. Further, when the coating composition is used, it is necessary that the antibacterial action is strong and the antibacterial spectrum is wide, that is, the antibacterial action is wide. The biguanide compound used in the present invention meets this condition.

Specific examples of the biguanide compound include chlorhexidine hydrochloride, chlorhexidine gluconate, chlorhexidine acetate, and polyhexamethylene biguanidine hydrochloride. Of these, chlorhexidine hydrochloride is particularly preferred in terms of antibacterial properties, handleability and cost.

It is necessary that the compounding amount of the biguanide compound is 0.1 to 15% by weight based on the polyester resin. If the amount is less than 0.1% by weight, the antibacterial and antifungal effects are unsatisfactory in terms of antibacterial and antifungal effects. And the mechanical properties are reduced.

The biguanide compound is added to the polyester resin for powder coatings and kneaded with a kneader or the like, or added together with a curing agent and other additives during coating to be kneaded.

When the resin composition of the present invention is used as a powder coating, it is necessary to incorporate a curing agent.

When a polyester resin having a hydroxyl group at the main terminal is used, an isocyanate-based curing agent or a glycoluril-based curing agent is used. Examples of isocyanate-based curing agents include Hurst's Vestagon B 1065, B
1530, BF 1540 "and the like. As the glycoluril-based curing agent, a tetramethoxymethylglycoluril curing agent, for example, “POWDERLINK 1174” manufactured by Cytec Corporation
And the like. The amount of the curing agent used is a functional group amount substantially corresponding to the hydroxyl group amount of the polyester resin, preferably
It is appropriate to set the range of 0.8 to 1.2 equivalents.

When a polyester resin having a carboxyl group at the main terminal is used, an epi-bis epoxy resin derived from bisphenol A and epichlorohydrin, a β-hydroxylamide curing agent, a triglycidyl isocyanurate curing agent, etc. Is used. As epi-bis type epoxy resin, Ciba Geigy's `` Araldite AER 6003 '', etc., as β-hydroxylamide-based curing agent, Ms's `` Primid XL-552 '', etc., as triglycidyl isocyanurate-based curing agent "Araldite PT 810" manufactured by Ciba-Geigy Co., Ltd. and the like.
The amount of the curing agent used is suitably in the range of the amount of the functional group substantially corresponding to the acid value of the polyester resin, preferably in the range of 0.8 to 1.2 times equivalent.

If necessary, a leveling agent, a curing catalyst, pigments such as titanium dioxide and carbon black, and other additives can be added.

[0029]

The polyester resin composition for powder coating of the present invention uses a biguanide compound having a strong antibacterial action, a broad antibacterial spectrum, excellent heat resistance, and a good dispersibility in polyester resin as an antibacterial and antifungal agent. Due to the heating in the powder coating manufacturing process and the baking process after coating, the antibacterial and antifungal effects are not reduced or colored, and exhibit excellent antibacterial and antifungal effects .

[0030]

Next, the present invention will be described by way of examples. In addition, the measuring method of a characteristic value is as follows. (a) Intrinsic viscosity The intrinsic viscosity was determined from the solution viscosity measured at 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent. (b) Hydroxyl value 3 g of the resin was dissolved in 50 ml of pyridine, acetylated by adding 5 ml of an acetylated solution composed of 6 ml of acetic anhydride and 44 ml of pyridine, and then titrated with a 0.5 N methanol solution of potassium hydroxide. (c) Acid value 0.5 g of the resin was dissolved in 50 ml of a mixed solvent of dioxane and distilled water at a weight ratio of 10/1, and the acid value was determined by titration with a 0.1 N methanol solution of potassium hydroxide. (d) Blocking resistance Powder coating powder with a height of 4 cm was placed on a bottomed glass tube of 3 cm in diameter and 7 cm in height.
cm, and left in a constant temperature bath at 40 ° C. for one week. Then, the powder coating was taken out by turning the glass tube upside down, and the state of the coating was observed and evaluated as follows. ：: good (there is no clump in the paint) ×: bad (there is a large clump of the paint agglomerated) (e) Specular gloss at 60 degrees Determined according to JIS K 5400. (f) Impact resistance In accordance with JIS K 5400, a coated steel plate is sandwiched between a shooting mold having a spherical surface with a diameter of 1.27 cm and a cradle with a depression matching it so that the coating film contacts the spherical surface. Was dropped vertically to determine the breaking height of the coating film. (If this value is 30 cm or more, it is a pass.) (G) Antibacterial property Paint the paint composition on a zinc phosphate treated steel sheet with a diameter of 30 mm so that the coating film becomes uniform, and bake at 180 ° C for 20 minutes. To obtain a test piece. Next, the test piece is attached to the center of the culture surface of a plate medium composed of 1 L of water, 40 g of glucose, 10 g of peptone, and 10 g of agar. Aspergillus niger, Penici
1 ml of a mixed spore suspension of llium funiculosum and Cryptococcus neoformans is evenly spread on the surface of the medium and on the test piece, and the plate is covered with a petri dish and cultured at 28 ° C. for 14 days.
The case where the bacteria did not grow is shown as "++", the case where the bacteria grew in 1/3 or less of the test piece was shown as "+", and the case where the bacteria grew about 1/3 or more was shown as "-".

Examples 1 to 4 and Comparative Examples 1 to 4 The starting compounds shown in Table 1 were placed in an esterification reactor in the amounts (mol parts) shown in Table 1, and the temperature was increased under a pressure of 0.25 MPa · G.
An esterification reaction was performed at 260 ° C. for 4 hours, and water produced was removed from the reaction system to prepare an esterified product. After transferring the obtained esterified product to a polycondensation reactor, 2 × 10 ⁻⁴ mol of antimony trioxide / mol of acid component was added as a catalyst, and 0.5 hPa
To a polycondensation reaction at 280 ° C for 3 hours.
0.45 dl / g of polyester was obtained. Next, the compound described in the column of depolymerization in Table 1 was added to the polyester in an amount (molar part) shown in Table 1, and the mixture was added under an atmospheric pressure and an inert atmosphere.
A depolymerization reaction was performed at 70 ° C. for 1 hour to obtain a polyester resin having the characteristic values shown in Table 1. (Comparative Example 4 did not perform a depolymerization reaction.) A blocked isocyanate-based curing agent was added to the obtained polyester resin; "Vestagon B 1530" manufactured by Huls Co., Ltd. was used as the functional group amount corresponding to the hydroxyl value of the polyester resin. Amount, antibacterial agent shown in Table 1 (A: chlorhexazine hydrochloride, B: chlorhexazine glucuronate) in the amount shown in Table 1 (% by weight based on polyester resin), total of resin and curing agent 1
0.3 parts by weight of dioctyltin maleate-based curing catalyst; "Stann OMF" manufactured by Sankyokisei Co., Ltd .; 0.3 parts by weight of butyl polyacrylate-based leveling agent; 1 part by weight of "Acronal 4F" manufactured by BASF; 0.5 parts by weight, titanium dioxide pigment; Rutile-type titanium dioxide "CR-90" manufactured by Ishihara Sangyo Co., Ltd. is added in a proportion of 50 parts by weight, and dry-blended with an FM 10B type Henschel mixer (manufactured by Mitsui Miike Works). The mixture was melt-kneaded at 110 ° C. using a mold co-kneader (manufactured by Buss), cooled, pulverized, and separated with a 140 mesh (106 μm) wire mesh to obtain a powder coating having an average particle size of 50 μm.

The obtained powder coating was electrostatically coated on a zinc phosphate-treated steel sheet, and baked at 180 ° C. for 20 minutes. The sex was evaluated. Table 1 shows the evaluation results of the coatings' blocking resistance and coating film performance.

[0033]

[Table 1]

Examples 5 to 8 and Comparative Examples 5 to 6 Using the starting compounds shown in Table 2, a polyester having an intrinsic viscosity of 0.45 dl / g was obtained in the same manner as in Example 1. Next, the compounds described in the column of depolymerization in Table 2 were added to the polyester in the amounts (mol parts) shown in Table 2, and a depolymerization reaction was performed at 250 ° C. for 2 hours under an atmospheric pressure in an inert atmosphere. A polyester resin having the characteristic values shown in Table 2 was obtained.

An epi-bis type epoxy resin-based curing agent, "Araldite AER 6003" manufactured by Ciba Geigy Co., Ltd. was added to the obtained polyester resin in an amount to become a functional group amount corresponding to the acid value of the polyester resin, as shown in Table 2. The amount of the antibacterial agent shown in Table 1 (% by weight based on the polyester resin) and the total amount of the resin and the curing agent were 100 parts by weight, and a 2-undecylimidazole-based curing catalyst;
Parts by weight, butyl polyacrylate-based leveling agent; BASF
1 part by weight of “Acronal 4F” and 0.5 parts of benzoin
Parts by weight, titanium dioxide pigment: 50 parts by weight of rutile type titanium dioxide "CR-90" manufactured by Ishihara Sangyo Co., Ltd., and dry blended with FM 10B type Henschel mixer (Mitsui Miike Seisakusho), then PR-46 type Using Ko-Knida (Buss) 1
After melting and kneading at 10 ° C, cooling and pulverizing, 140 mesh (106μ
m) to obtain a powder coating having an average particle size of 50 μm.

The obtained powder coating material was electrostatically coated on a zinc phosphate treated steel plate and baked at 180 ° C. for 20 minutes. The sex was evaluated. Table 2 shows the evaluation results of the coating resistance and the coating film performance.

[0037]

[Table 2]

In Examples 1 to 8, good coating films having excellent antibacterial properties were obtained.

On the other hand, in Comparative Examples 1 and 5, the amount of the antibacterial agent was small, so that sufficient antibacterial properties were not exhibited. In Comparative Examples 2 and 6, the amount of the antibacterial agent was large, and the strength of the coating film was high. Was low. In Comparative Example 3, the intrinsic viscosity of the polyester resin was low, so that the blocking resistance was inferior. In Comparative Example 4, the intrinsic viscosity was too large, so that the resin was difficult to pulverize to obtain a powder coating that could be used for testing. Could not.

[0040]

According to the present invention, there is provided a polyester resin composition for powder coating which can be produced at low cost, has excellent antibacterial and antifungal properties and gives a good coating film.

Claims (1)

[Claims] 1. An antibacterial and antifungal property, wherein a biguanide compound is contained in a polyester resin for powder coatings having an intrinsic viscosity of 0.15 to 0.40 dl / g in an amount of 0.1 to 15% by weight based on the polyester resin. Polyester resin composition for powder coatings.