JPH0625561A - Antimicrobial powder coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition useful for building, electrical and electronic parts, etc., having excellent persistence, durability and weather resistance without causing change of color, comprising a specific compound and a resin for powder coating. CONSTITUTION:This coating composition comprises (A) preferably 0.5-10 pts.wt. (based on 100 pts.wt. composition) compound of the formula [M<1> is one or more metallic ions selected from silver, copper, zinc, tin, mercury, lead, iron, cobalt, nickel, manganese, arsine, antimony, bismuth, barium, cadmium and chromium; A is alkaline (earth) metal ion, ammonium ion or hydrogen ion; M<2> is tetravalent metal; (n) is 0-6; a+b is 1a+mb=1 or 2; (c) and (d) are in correlation where (c) is 2 and (d) is 3 when 1a+mb=1 and (c) is 1 and (d) is 2 when 1a+mb=2; with the proviso that (1) is valence of M<1>; (m) is valence of A] and (B) a resin for powder coating such as PVC or nylon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition comprising a specific phosphate compound having antibacterial properties and a resin for powder coating. The composition of the present invention and a coating film obtained from the resin composition discolor over a long period of time. It exerts an antibacterial effect without doing. INDUSTRIAL APPLICABILITY The composition of the present invention is useful as a coating composition capable of imparting antibacterial properties to the surface of metal products, plastic products, etc., which require antifungal, antialgal and antibacterial properties.

[0002]

2. Description of the Related Art In products made of various materials such as metals, plastics, ceramics, etc., a coating film is formed on the surface of various products in order to prevent rust and defects and enhance the appearance, which is well known. As described above, in construction, electrical products, electronic parts, fuel containers, food processing equipment, various plumbing work, etc., organic pigments or spots on the surface of the coating film caused by mold spores or hyphae, or secreted by mold The acid erodes the coating film, or the coated metal substrate is eroded, which makes the appearance extremely unsightly, and often causes damage such as promoting deterioration of the function of the coated object. .

[0003] In order to prevent these damages caused by mold, antifungal paints have been developed. Antifungal paints are compounds that have a fungicidal effect added to the paint resin to show the antibacterial effect of the antifungal agent in the coating film, but those currently in practical use are compounds with antifungal effects. It is a solution-type paint in which an organic compound is blended. In recent years, in order to prevent air pollution and fire due to organic solvents and improve the working environment, solvent-free powder coatings are preferred, and powder coatings using various resins as coating materials have been developed. .

On the other hand, organic compounds have been mainly used until now as compounds having an antifungal effect. However, organic antifungal agents have problems in heat resistance, durability, etc. A mildew was desired. With subsequent development, as an antibacterial agent that eliminates the drawbacks of conventional antifungal agents, recently, an inorganic antibacterial agent in which a metal exhibiting antibacterial properties such as silver and copper is supported on activated carbon, apatite, zeolite, etc. is known. Became.
However, these inorganic antibacterial agents cause discoloration under severe environments such as irradiation with ultraviolet rays, and there is room for improvement in blending them as paint components.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a coating composition comprising an antibacterial agent and a resin for powder coating. By using this composition, the antibacterial effect can be maintained for a long period of time and ultraviolet rays can be applied. It is an object of the present invention to provide a coating composition capable of forming a coating film excellent in durability without discoloring even under severe environment such as irradiation with.

[0006]

[Means for Solving the Problems] The antibacterial agent mixed in the antibacterial paint is required to satisfy the following conditions. Excellent antibacterial effect. Being safe to the human body. Do not deteriorate the physical properties of paints and coatings. Excellent durability and durability. The present inventors have proposed a zirconium phosphate salt, which is an excellent inorganic antibacterial agent that does not cause discoloration even under a severe environment such as irradiation with ultraviolet rays (Japanese Patent Laid-Open No. 3-8390).
5, JP-A-3-83906), and as a result of intensive studies to obtain a powder coating composition that solves the problems of conventional antifungal coatings by utilizing the excellent properties of this antibacterial agent, we found that An antibacterial powder coating composition consisting of a specific zirconium phosphate salt and a resin for powder coating, which has been proposed in 1), exhibits mold resistance and antibacterial properties for a long time, and forms a coating film that is not discolored and has excellent durability. It was found to be extremely effective in achieving the above, and the present invention has been completed. That is, the present invention relates to an antibacterial powder coating composition comprising a compound represented by the following general formula [1] and a resin for powder coating. M ¹ _{a Ab} M ² _c (PO ₄ ) _d · nH ₂ O [1] (M ¹ is silver, copper, zinc, tin, mercury, lead, iron, cobalt,
At least one metal ion selected from nickel, manganese, arsenic, antimony, bismuth, barium, cadmium or chromium, A is an alkali metal ion,
At least one ion selected from alkaline earth metal ions, ammonium ions or hydrogen ions,
M ² is a tetravalent metal, n is a number satisfying 0 ≦ n ≦ 6, and a and b are both la + mb = 1 or la + mb
= 2, and c and d are la + mb = 1, c = 2, d = 3, and la + mb = 2, c = 1, d
= 2. However, 1 is the valence of M ¹ and m is the valence of A. )

The present invention will be described in detail below.

Resin for Powder Coating The resin used in the present invention may be any resin as long as it can be used for powder coating. The type of resin may be any of natural resin, semi-synthetic resin and synthetic resin, and may be any of thermoplastic resin and thermosetting resin. Specific resins include, for example, polyvinyl chloride, cellulose acetate and propionate, polypropylene, polyester, chlorinated polyester, nylon, epoxy and acrylic.

○ Phosphate Compound The compound used in the present invention is a compound represented by the following general formula [1]. M ¹ _{a Ab} M ² _c (PO ₄ ) _d · nH ₂ O [1] (M ¹ is silver, copper, zinc, tin, mercury, lead, iron, cobalt,
At least one metal ion selected from nickel, manganese, arsenic, antimony, bismuth, barium, cadmium or chromium, A is an alkali metal ion,
At least one ion selected from alkaline earth metal ions, ammonium ions or hydrogen ions,
M ² is a tetravalent metal, n is a number satisfying 0 ≦ n ≦ 6, and a and b are both la + mb = 1 or la + mb
= 2, and c and d are la + mb = 1, c = 2, d = 3, and la + mb = 2, c = 1, d
= 2. However, 1 is the valence of M ¹ and m is the valence of A. )

The compound represented by the above general formula [1] is
When a + mb = 1, each coefficient of c = 2 and d = 3,
Amorphous or a crystalline compound belonging to the space group R3c, which represents a compound in which each constituent ion forms a three-dimensional network structure, has a coefficient of c = 1 and a coefficient of d = 2 when la + mb = 2. It represents a compound whose constituent ions form a layered structure. The phosphate-based compound used in the present invention has little discoloration when exposed to sunlight,
A crystalline compound having an amorphous or three-dimensional network structure having coefficients of + mb = 1 and c = 2, d = 3 is preferable, and a crystalline compound is particularly preferable.

M ¹ in the above general formula [1] is known as a metal exhibiting antifungal, antibacterial and antialgal properties (antibacterial metal ion). Among these, silver is
In addition to safety, it is particularly effective as a metal capable of enhancing antifungal, antibacterial and antialgal properties.

A in the above general formula [1] is at least one ion selected from an alkali metal ion, an alkaline earth metal ion, an ammonium ion and a hydrogen ion, and preferred specific examples are lithium, sodium and potassium. There is an alkali metal ion such as, and an alkaline earth metal ion such as magnesium or calcium or hydrogen ion, and among these, lithium, sodium, ammonium ion and hydrogen ion are preferable from the viewpoint of stability of the compound and availability at low cost. Ion.

M ² in the above general formula [1] is a tetravalent metal, and preferred specific examples thereof include zirconium, titanium or tin. Considering the safety of the compound, zirconium and titanium are particularly preferred. It is a valent metal.

The following are specific examples of the phosphate compound represented by the general formula [1]. Ag _0.005 Li _0.995 Zr ₂ (PO ₄ ) ₃ Ag _0.01 (NH ₄ ) _0.99 Zr ₂ (PO ₄ ) ₃ Ag _0.05 Na _0.95 Zr ₂ (PO ₄ ) ₃ Ag _0.2 K _0.8 Ti ₂ (PO ₄ ) ₃ Ag _0.1 H _0.9 Zr ₂ (PO ₄ ) ₃ Ag _0.05 H _0.05 Na _0.90 Zr ₂ (PO ₄ ) ₃ Ag _0.05 H _0.55 Na _0.40 Zr ₂ (PO ₄ ) ₃ and the same charge amount as silver ions per 1 mol of the compound. Then, Ag in each of the above equations is changed to Z
Compound substituted with n, Mn, Ni, Pb, Hg, Sn, or Cu, Ag _0.001 Li _1.999 Zr (PO ₄ ) ₂ Ag _0.01 Na _1.99 Zr (PO ₄ ) ₂ Ag _0.01 K _1.99 Sn (PO ₄ ) ₂ · _{1.2H 2 O Ag 0.1 (NH 4} ) 1.9 Ti (PO 4) 2 · 4H 2 O Ag 0.02 H 1.98 Zr (PO 4) 2 · 1.7H 2 O Ag 0.01 H 0.04 Na 1.95 Zr (PO 4) 2 Ag _0.01 H _0.54 Na _1.45 Zr (PO ₄ ) ₂ and Ag in each of the above formulas are adjusted so as to have the same charge amount as that of silver ions per 1 mol of the compound.
A compound substituted with n, Mn, Ni, Pb, Hg, Sn, or Cu.

The phosphate compound used in the present invention preferably has an average particle size of 1 μm or less because it facilitates the formation of a thin and uniform coating film.

The method for synthesizing the phosphate compound used in the present invention includes a calcination method, a wet method, a hydrothermal method and the like, which can be easily obtained as follows, for example. -Synthesis of network structure phosphate When synthesized by the firing method, compounds containing alkali metal such as lithium carbonate (Li ₂ CO ₃ ) or sodium carbonate (Na ₂ CO ₃ ), zirconium oxide (ZrO ₂ ) etc. Compounds containing zirconium and ammonium dihydrogen phosphate (NH ₄ H
₂ PO ₄ ) and other compounds having a phosphoric acid group are mixed in a molar ratio of about 1: 4: 6, and the mixture is calcined at 1100-1400 ° C. to give a compound represented by the general formula [2] A ′. _x Zr ₂ (PO ₄ ) ₃ [2] (A ′ is at least one metal ion selected from alkali metal ions or alkaline earth metal ions, x
Is 1 when A ′ is monovalent, and is 1/2 when A is divalent). this,
By dipping in an aqueous solution containing silver ions at an appropriate concentration at room temperature to 100 ° C, the compound represented by the general formula [1] is obtained. The compound in which the A ion in the general formula [1] is a hydrogen ion is obtained by immersing the compound represented by the general formula [2] in an aqueous solution of an inorganic acid such as nitric acid, sulfuric acid and hydrochloric acid at room temperature to 100 ° C. Therefore, the general formula H _{(1-z) A'z} M ₂ (PO ₄ ) ₃ (z is a number less than 0 or 1)
The compound [2] represented by the formula [1] is obtained, and the compound [2] represented by the general formula [1] is obtained by immersing the compound [2] in an aqueous solution containing silver ions at an appropriate concentration. Further, in the case of synthesizing by a wet method, oxalic acid and phosphoric acid are added to this while stirring an aqueous solution of zirconium oxynitrate and sodium nitrate. The pH of the reaction solution was adjusted to 3.5 with an aqueous solution of caustic soda, the mixture was heated under reflux for 78 hours, and the precipitate was filtered, washed with water, dried and pulverized to obtain reticulated zirconium phosphate [NaZr ₂ (PO ₄ ) ₃ ]. . The compound represented by the general formula [1] is obtained by immersing this in an aqueous solution containing an antibacterial metal at an appropriate concentration.

Synthesis of Layered Structure Phosphate An oxychloride containing a tetravalent metal such as zirconium oxychloride, titanium oxychloride or tin oxychloride, or a tetravalent metal such as titanium or tin in a concentrated aqueous solution of phosphoric acid. Was added, and the mixture was heated under reflux for 24 hours, and the precipitate was filtered, washed with water, dried and pulverized, and zirconium phosphate [Zr (HPO
₄ ) ₂ · H ₂ O] or the like is obtained, and this is added to an aqueous solution of a nitrate such as an alkali metal, stirred, washed with water, dried and pulverized to obtain a compound represented by the general formula [3]. . A _2x Zr (PO ₄ ) ₂ · nH ₂ O [3] (A, x and n have the same meanings as above) By immersing this in an aqueous solution containing an antibacterial metal at an appropriate concentration, A compound represented by the formula [1] is obtained.

The value of a in the general formula [1] is the concentration of the antibacterial metal ion in the aqueous solution in which the compound represented by the general formula [2] or [3] is immersed, and the value of the general formula [a] in the aqueous solution. By adjusting the time, temperature, or the like for immersing the compound represented by 2] or [3], it can be appropriately adjusted according to the required characteristics and use conditions.

In order to exhibit antifungal, antibacterial and antialgal properties, the larger the value of a in the general formula [1] is, the better.
When the value of a is 0.001 or more, antifungal, antibacterial and antialgal properties can be sufficiently exhibited. However, in order to exert antifungal, antibacterial and antialgal properties for a long time while considering economic efficiency, it is preferable to adjust the value of a to 0.01 or more and 0.5 or less.

The phosphate compounds used in the present invention are stable to exposure to heat and light, and their structure and composition are completely changed even after heating at 500 ° C, and in some cases 800 ° C to 1100 ° C. No discoloration occurs even when irradiated with ultraviolet rays. Further, the phosphate used in the present invention does not come into contact with water in a liquid state, and the skeleton structure is not changed even in an acidic solution. Therefore, processing and storage when mixed with various powder coating resins, and like conventional antibacterial agents,
When used, it is not restricted by heating temperature or light shielding conditions.

The phosphate compound used in the present invention is excellent in safety for the human body and has an LD ₅₀ (mouse).
Is 5000 mg / kg or more, mutagenicity is negative,
The rabbit has no primary skin irritation.

○ Mixing ratio of antibacterial agent The preferable mixing ratio of the antibacterial agent is the antibacterial powder coating composition 1
0.005 to 5 parts by weight (hereinafter, simply referred to as "parts")
It is 0 part, and more preferably 0.5 to 10 parts in view of antibacterial effect and economical efficiency.

Other components: Components that have been conventionally used as powder coating components, such as pigments, UV absorbers, antioxidants, stabilizers, fillers, surfactants, and thermosetting powder coatings. In the case of containing a resin, a curing agent, a curing accelerator, etc. can be optionally used within a range that does not impair the specific antibacterial property derived from the phosphate compound used in the present invention.

Production Method In the antibacterial coating composition of the present invention, the phosphate compound represented by the above general formula [1], the resin for powder coating and other desired components are adjusted to the characteristics of the resin used. It can be easily prepared by a method of mixing, mixing or kneading while heating and pressurizing or reducing the pressure at an appropriate temperature or pressure, and the specific operation thereof may be carried out by a conventional method. Generally, when a powder coating resin and a powdered additive are mixed, they are melt-mixed in order to homogenize these components, but in the present invention, these powder components are not melted, A sufficiently uniform coating film can be easily formed by simply mixing with a conventional mixer. This is probably because the phosphate-based compound used in the present invention is in the form of fine particles, and therefore, by simply mixing it with the powder coating resin, it is not possible for the fine particles to uniformly coat the surface of the powder coating resin powder. It is presumed that there is, but details are unknown. The antibacterial powder coating composition thus obtained does not deteriorate at the time of mixing the antibacterial agent and the resin for powder coating and at the time of storing or using the antibacterial powder coating composition thereafter, and is severe. It has antifungal, antibacterial and antialgal properties for a long time even in the environment.

Coating Method The antibacterial powder coating composition of the present invention thus obtained has a phosphate compound, which is an antibacterial agent component, having excellent chemical and physical stability. Therefore, there is no particular limitation on the coating conditions, and any conventionally known method can be adopted. Specifically, there are the following methods. That is, fluidized immersion method, electrostatic spraying method, electrostatic current immersion method,
Electrostatic curtain coating method, electrostatic disk method, in-line electrostatic current immersion coating method, etc. (1977, published by General Coating Technology Center Co., Ltd., Dr. Emery P. Mille
ret. al, Translated by Takeshi Ito, "Powder Coating Technology").

Use of Powder Coating Composition The powder coating composition of the present invention can be used in various fields requiring antifungal, antialgal and antibacterial properties, and particularly, it contains a large amount of water. It is effective for use in the environment.
Specific applications include, for example, bathrooms of general houses, kitchens, living rooms, closets, breweries, food factories, fruit and vegetable storage, drug warehouses, pharmaceutical factories, cosmetics factories, paper mills, spinning factories, office buildings, schools, There are places where mildew is likely to occur, such as hot water pools, hospitals, vehicles, ships, washing machines, dishwashers and other electrical products, semiconductors, electronic components such as resistors and capacitors, fuel containers, food processing equipment, and various piping work. .

Hereinafter, the present invention will be described more specifically by way of examples.

[Reference example] (Preparation of antibacterial agent) An aqueous solution of zirconium sulfate and an aqueous solution of ammonium dihydrogen phosphate were mixed so that the ratio of zirconium to phosphorus was 2: 3 to form a precipitate, and a sodium hydroxide solution was added. After the pH was adjusted to 2 using an aqueous solution, crystalline zirconium phosphate was obtained by heating under hydrothermal condition at 150 ° C. for 24 hours. The phosphate compound obtained above was added to an aqueous solution of silver nitrate, stirred at room temperature for 4 hours, thoroughly washed with water, dried and pulverized to obtain an antibacterial agent. The obtained antibacterial agent is a white powder having an average particle size of 0.47 μm.

[0028]

[Table 1]

Example 1 (Preparation of antibacterial powder coating composition and formation of coating film) In 100 parts of Nylon resin powder (nylon-11, particle size 80 to 200 μm) manufactured by Nippon Rilsan Co., Ltd., as a reference example. 0.5 part of the prepared antibacterial agent was blended, and this was used to prepare an antibacterial powder coating composition using a Henschel mixer. Using this composition, 20 was placed on a stainless steel plate (7 cm × 15 cm) preheated to 250 ° C. by a fluidized-bed method.
A coating film having a film thickness of 0 to 300 μm was formed to prepare an antibacterial plate (Plate 1). Further, only the nylon resin powder containing no antibacterial agent was similarly coated by the fluidized-bed method to prepare a plate (blank 1).

Example 2 (Preparation of antibacterial powder coating composition and formation of coating film) 100 parts of polyethylene resin powder was mixed with 1.0 part of the antibacterial agent prepared in Reference Example and extruded Then, by pulverizing, an antibacterial powder coating composition was prepared. Using this composition, in the same manner as in Example 1, a coating film having a film thickness of 200 to 300 μm was formed on a stainless steel plate by the fluid immersion method to prepare an antibacterial plate (plate 2). Further, only the polyethylene resin powder containing no antibacterial agent was similarly coated by the fluidized dipping method to prepare a plate (blank 2).

Example 3 (Preparation of antibacterial powder coating composition and formation of coating film) 1.0 part of the antibacterial agent prepared in Reference Example was added to 100 parts of polyester resin powder (particle size 10 to 100 μm). Was mixed and mixed with a Henschel mixer to prepare an antibacterial powder coating composition. Using this composition, a coating film was formed on a stainless plate by an electrostatic coating method to prepare an antibacterial plate (plate 3). The coating conditions are as follows. -Voltage: -60 kv-Heating: 200 ° C., 10 minutes-Film thickness: 60 μm Further, only the polyester resin powder containing no antibacterial agent was similarly coated by the electrostatic coating method to prepare a plate (blank 3).

Example 4 (Preparation of antibacterial powder coating composition and formation of coating film) Acrylic resin powder (particle size 10 to 100 μm) 10
An antibacterial powder coating composition was prepared by blending 0 part of the antibacterial agent prepared in Reference Example with 1.0 part and mixing the mixture with a Henschel mixer. Using this composition, a coating film was formed on a stainless steel plate in the same manner as in Example 3 to prepare an antibacterial plate (plate 4).
The coating conditions are as follows. -Voltage: -60 kv-Heating: 180 ° C., 20 minutes-Film thickness: 60 μm Further, only the acrylic resin powder containing no antibacterial agent was similarly coated by the electrostatic coating method to prepare a plate (blank 4).

Comparative Example 1 (Preparation of antibacterial powder coating composition and formation of coating film) A mixture of 100 parts of acrylic resin powder and 1.0 part of benzirconium chloride as an organic antibacterial agent was extruded. After molding, the composition was pulverized to prepare an antibacterial powder coating composition. Using this composition, a coating film having a film thickness of 60 μm was formed on a stainless steel plate (7 cm × 15 cm) by an electrostatic coating method to prepare an antibacterial plate (plate 5). The resulting coating film has conical ridges having a diameter and height of 0.1 to 0.3 mm formed on its surface,
It was rough.

Example 5 (Antibacterial Test) The antibacterial activity of the test pieces (5 cm × 5 cm) cut out from the plates prepared in Examples 1 to 4 and Comparative Example 1 was evaluated by the following method. Escherichia coli was used as a test bacterium, and the number of bacteria was 10 ⁴ to 1 per 5 cm × 5 cm of the plate.
0 ⁵ become as the Kin'eki uniformly inoculated into 0.2ml surface, covering the surface with plastic wrap, after storage for 6 hours at 37 ° C., plates in measuring the number of bacteria medium (SCDLP broth) Surviving bacteria were washed out, and this washing solution was used as a test solution. The viable cell count of this test solution was measured by the pour plate culture method (37 ° C. for 2 days) using a bacterial cell count medium and converted into the viable cell count per 5 cm × 5 cm of the plate. Table 2 shows the results of the antibacterial test obtained as described above. The viable cell counts at 0 and 6 hours after the start of storage in 0.2 ml of the bacterial solution were 5.0 × 10 ⁴ and 3.7 × 10 ⁴ for the plate prepared in Example 1, respectively. And in the case of the plate prepared in Example 2, each is 2.4 × 10 ^4.
And 3.3 × 10 ⁴ , and in the case of the plate prepared in Example 3 (Example 3), 2.4 × 10 ⁴ and 2.3, respectively.
× 10 ⁴ , and in the case of the plate manufactured in Example 4 (Example 4), 8.8 × 10 ⁴ and 4.5 × 10 ^{4 respectively.}
And in the case of the plate produced in Comparative Example 1, 2.
4 × 10 ⁴ and 2.3 × 10 ⁴ .

[0035]

[Table 2]

Example 3 "Weather resistance test" The plates prepared in Examples 3 and 4 were measured for weather resistance using a weather resistance tester UC-1 manufactured by Toyo Seiki Seisaku-sho, Ltd. The test condition of UC-1 is that one cycle is 2 hours, and the ultraviolet rays of 350 nm or less are irradiated at 60 ° C. 1
It consists of a step of time and a step of 1 hour of leaving at 40 ° C. in an atmosphere having a humidity of 95% or more. A color difference meter SZ-Σ80 manufactured by Nippon Denshoku Industries Co., Ltd. was used to measure the color (L, a, b) after 10 cycles of the weather resistance test, and this color was compared with the color immediately after molding the plate. Color difference by doing
E was determined and the results are shown in Table 3.

[0037]

[Table 3]

From the above Table 3, it can be seen that the plate coated with the coating composition of the present invention shows weather resistance almost equal to that in the case where no antibacterial agent is contained and is excellent in weather resistance.

[0039]

EFFECT OF THE INVENTION By using the composition of the present invention, the antibacterial effect can be maintained for a long time, and the coating film does not discolor even under severe environment such as irradiation with ultraviolet rays and has excellent durability. be able to.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Takagi 23-chome, 17-chome, Showa-cho, Minato-ku, Nagoya, Aichi Toagosei Chemical Industry Co., Ltd. Nagoya factory

Claims (1)

[Claims] 1. An antibacterial powder coating composition comprising a compound represented by the following general formula [1] and a resin for powder coating. M ¹ _{a Ab} M ² _c (PO ₄ ) _d · nH ₂ O [1] (M ¹ is silver, copper, zinc, tin, mercury, lead, iron, cobalt,
At least one metal ion selected from nickel, manganese, arsenic, antimony, bismuth, barium, cadmium or chromium, A is an alkali metal ion,
At least one ion selected from alkaline earth metal ions, ammonium ions or hydrogen ions,
M ² is a tetravalent metal, n is a number satisfying 0 ≦ n ≦ 6, and a and b are both la + mb = 1 or la + mb
= 2, c and d are c = 2 and d = 3 when la + mb = 1, and c = d when la + mb = 2.
1 and d = 2. However, 1 is the valence of M ¹ and m is the valence of A. )