JPH059356A - Vinyl chloride-based resin composition for agriculture - Google Patents

Abstract

PURPOSE:To obtain the title composition having excellent plateout for a long period of time and improved weatherability by blending a vinyl chloride resin with a specific hindered amine compound and a specific phosphorus-containing metal salt. CONSTITUTION:A vinyl chloride resin is blended with (A) a hindered amine compound shown by formula I (A is bifunctional-tetrafunctional organic polyfunctional amine residue; n is 2-4; R1 is H, 1-8C alkyl, 1-8C acyl or oxygen liberating group) and (B) a phosphorus-containing metal salt shown by formula II and/or formula III (R3 and R5 are 1-30C alkyl, aryl, arylalkyl or alkylaryl; R4 is H or O-R3; M1 is alkaline earth metal, Zn or Al; a is 2 or 3; b is 0 or 1; c is 0 or 1; M2 is alkaline earth metal or Zn when c=0 and M2 is Al when c=1) to give the objective composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural vinyl chloride resin composition, and more specifically, by adding a specific triazine-based hindered amine light stabilizer and a phosphorus-containing metal salt, a plate-out property and a weather resistance can be improved. The present invention relates to a significantly improved vinyl chloride resin composition for agriculture.

[0002]

2. Description of the Related Art Vinyl chloride resins are used in a wide range of applications because they are characterized by excellent weather resistance, high strength, and good transparency. In particular, soft products containing a plasticizer are easy to process and are widely used as agricultural films and sheets.

However, vinyl chloride resins are inferior in stability to heat and light, and when heat-molded.
There is a drawback that thermal decomposition is liable to occur mainly due to dehydrochlorination, which often causes remarkable inconveniences such as deterioration of mechanical properties of processed products and deterioration of color tone. In order to eliminate these drawbacks, various heat stabilizers such as carboxylic acid metal salts and organic phosphoric acid ester metal salts are used alone or in combination, and the stabilization during heat molding is almost satisfactory. The expected result is obtained.

Although vinyl chloride resins have relatively good weather resistance, in the case of agricultural vinyl chloride resin compositions that are used outdoors for a long period of time, deterioration in color tone, reduction in strength, and transparency are caused. In many cases, problems such as deterioration were caused and the practicality thereof was greatly impaired.

Therefore, in the vinyl chloride resin composition for agriculture, the use of a light stabilizer is indispensable, and conventionally, an ultraviolet absorber such as a benzophenone type or a benzotriazole type has been added. However, their weather resistance is insufficient, and when added in large amounts, they have the drawbacks of causing blooming and absorbing the long-wavelength side of ultraviolet rays to adversely affect the growth of crops. Attempts have been made to add the light stabilizer described in JP-A-57-1.
68933, JP-A-57-168934,
JP-A-58-142928).

Although the weather resistance was improved to some extent by adding these hindered amine light stabilizers,
There was a drawback that plate-out was likely to occur during molding. For this reason, a method of directly grafting a hindered amine-based stabilizer onto a vinyl chloride-based resin (JP-A 1-2)
No. 99854), and addition of a hindered amine-based stabilizer having a triazine group has been tried (JP-A-62-115054 and 64-64).
24842), the plate-out property is improved by these methods, but it is still insufficient, and the weather resistance is not satisfactory.

Therefore, it has been strongly desired to develop a vinyl chloride resin composition having good plate-out property and good weather resistance for a long period of time.

[0008]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above-mentioned circumstances, and as a result, a combination of a hindered amine compound and a phosphorus-containing metal salt has an effect of improving the weather resistance of a vinyl chloride resin. Was found to be large.

As a result of further studies based on the above findings, the present inventors have found that a triazine-based hindered amine compound has a remarkable effect of improving the weather resistance of a vinyl chloride-based resin when combined with a phosphorus-containing metal salt. Large and unlike conventional findings, when combined with a phosphorus-containing metal salt, the high molecular weight triazine-based hindered amine compound has a significantly large plate-out, but even a triazine-based hindered amine compound has a specific structure. Only the thing found that plate out was few, and this invention was reached.

That is, the present invention provides a vinyl chloride resin,
(A) General formula (I) represented by the following chemical formula 3 (same as chemical formula 1)
At least one hindered amine compound represented by the formula (b) and the following general formula (I)
The present invention provides a vinyl chloride resin composition for agriculture, which comprises at least one phosphorus-containing metal salt represented by I) and / or (III).

[0011]

[Chemical 3] (A represents a residue of a divalent to tetravalent organic polyvalent amine,
A is bonded to the triazine ring via a nitrogen atom,
The residue may have a nitrogen atom which is not bonded to the triazine ring. n shows 2-4. R ₁ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, or an oxygen free group. R ₂ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. )

[0012]

[Chemical 4] (In the formula, R ₃ and R ₅ represent an alkyl group having 1 to 30 carbon atoms, an aryl group, an arylalkyl group or an alkylaryl group, and R ₄ represents a hydrogen atom or a group represented by —OR _{3. 1} represents an alkaline earth metal, a zinc atom, or an aluminum atom, a represents 2 or 3, b represents 0 or 1, a + b represents a valence of a metal, c represents 0 or 1, and M ₂ represents c = 0. Represents an alkaline earth metal or zinc atom, and c = 1 represents an aluminum atom.)

The present invention having the above gist will be described in detail below.

In the above general formula (I), A represents a residue of an organic polyvalent amine having 2 to 4 primary and / or secondary amino groups, and the organic polyvalent amine giving the residue A is Examples thereof include organic polyamines represented by the general formula (IV) represented by the following chemical formula 5.

[0015]

[Chemical 5] (R ₆ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. R ₇ represents an alkylene group having 2 to 18 carbon atoms, R ₈ represents an alkylene group having 2 to 18 carbon atoms, an oxygen-containing complex A cyclic group, an alicyclic group or an alkanetriyl group is shown.
R ₉ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and two R ₉ may combine with each other to form an alkylene group. d, e and f represent 0 or 1, and d + e + f is 0 to 2)

Examples of the organic polyvalent amine represented by the above general formula (IV) include ethylenediamine, propylenediamine, hexamethylenediamine, undecamethylenediamine, piperazine, 3,9-bis (3-aminopropyl)- 2,4,8,10-Tetraoxaspiro [5.
5] Undecane, diethylenetriamine, 1,6,11
-Triaminoundecane, 1,8-diamino-4-aminomethyloctane, triethylenetetramine, N, N '
-Bis (3-aminopropyl) ethylenediamine, N,
Examples thereof include N'-bis (3-aminopropyl) piperazine.

In the general formula (I), the alkyl group represented by R ₁ is an unsubstituted alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl and 2-ethylhexyl. Groups and substituted alkyl groups such as benzyl, phenylethyl, 2-hydroxyethyl, 2,3-epoxypropyl and the like, and as the acyl group, acetyl, propionyl, acryloyl, methacryloyl, butyroyl,
Examples of the alkyl group represented by R ₂ , R ₆ or R ₉ in the above general formula (I) or (IV) include octanoyl, methyl, ethyl, propyl, isopropyl,
Butyl, isobutyl, pentyl, hexyl, octyl,
2-ethylhexyl, decyl, dodecyl, tridecyl,
Examples include tetradecyl, octadecyl, dimethylaminopropyl, methoxyethyl and the like.

Next, typical examples of the compound represented by the above general formula (I) used in the present invention are shown. In addition, the following
In the structural formulas ( ₁₎ to (19), B _{1 to} B ₄ represent groups represented by the following Chemical formula 6.

[0019]

[Chemical 6]

[0020]

[Chemical 7]

[0021]

[Chemical 8]

[0022]

[Chemical 9]

[0023]

[Chemical 10]

[0024]

[Chemical 11]

[0025]

[Chemical formula 12]

[0026]

[Chemical 13]

[0027]

[Chemical 14]

[0028]

[Chemical 15]

[0029]

[Chemical 16]

[0030]

[Chemical 17]

[0031]

[Chemical 18]

[0032]

[Chemical 19]

These compounds are known compounds,
A well-known method for synthesizing a triazine-based hindered amine compound, for example, reacting cyanuric chloride with a 4-piperidylamine compound to synthesize 2-chloro-4,6-bis (polyalkylpiperidin-4-yl) triazine ( It can be easily prepared by alkylating or acylating the 1-position of the piperidyl group if necessary), and then reacting this with a polyvalent amine compound.

The triazine-based hindered amine compound represented by the above general formula (I) used in the present invention is
They may be added alone or in combination of two or more, and the addition amount thereof is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 100 parts by weight of the vinyl chloride resin. ~ 3 parts by weight.

In the above general formulas (II) and (III), R ₃ and
Examples of the alkyl group represented by R ₅ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, sec-butyl, amyl, sec-amyl, hexyl, octyl, isooctyl, 2-ethylhexyl, nonyl and decyl. , Undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, triacontyl and the like.

Examples of the arylalkyl group represented by R ₃ and R ₅ include benzyl, α-methylbenzyl, α, α-dimethylbenzyl and the like.

Examples of the aryl group represented by R ₃ and R ₅ include phenyl, naphthyl, biphenyl and the like.

The alkylaryl group represented by R ₃ and R ₅ includes tolyl, xylyl, ethylphenyl, butylphenyl, tert-butylphenyl, octylphenyl, nonylphenyl, dinonylphenyl, decylphenyl, dodecylphenyl and the like. Can be given.

Therefore, examples of the phosphorus-containing metal salt used in the present invention include the following compounds.

[0040]

[Chemical 20]

[0041]

[Chemical 21]

[0042]

[Chemical formula 22]

[0043]

[Chemical formula 23]

[0044]

[Chemical formula 24]

[0045]

[Chemical 25]

[0046]

[Chemical formula 26]

[0047]

[Chemical 27]

[0048]

[Chemical 28]

[0049]

[Chemical 29]

[0050]

[Chemical 30]

[0051]

[Chemical 31]

[0052]

[Chemical 32]

[0053]

[Chemical 33]

[0054]

[Chemical 34]

(In the formula, alkaline earth metal or zinc atom or aluminum atom is shown, a is 2 or 3, b is 0 or 1, and a + b is the valence of the metal.)

The phosphorus-containing metal salts represented by the above general formulas (II) and / or (III) may be added alone or in combination of two or more kinds. It is preferably 0.1 with respect to 100 parts by weight of the vinyl resin.
To 5 parts by weight, more preferably 0.5 to 3 parts by weight.

The vinyl chloride resin used in the present invention includes polyvinyl chloride homopolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-ethylene copolymers,
Vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-alkyl A cycloalkyl or aryl maleimide copolymer,
Vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer,
Vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer, vinyl chloride-acrylonitrile copolymer, Examples thereof include vinyl chloride copolymers such as vinyl chloride-urethane copolymer, and these vinyl chloride resins and polyethylene, polypropylene, polybutene,
Α-olefin polymers such as poly-3-methylbutene or ethylene-vinyl acetate copolymers, polyolefins such as ethylene-propylene copolymers and copolymers thereof,
Polystyrene, acrylic resin, copolymer of styrene and other monomer (eg maleic anhydride, butadiene, acrylonitrile, etc.), acrylonitrile-butadiene-styrene copolymer, methacrylic acid ester-butadiene-styrene copolymer, polyurethane It may be a blended product with.

Further, the composition of the present invention can be prepared by adding Li, K, Na, Mg,
The combined use of a metal carboxylate such as Sr, Ca, Ba, Zn, Cd, Sn, Pb, or organic Sn, a phenolate, or a mercaptide significantly improves the stabilizing effect.

Examples of the carboxylic acid constituting the metal carboxylate include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, neodecanoic acid, 2-ethylhexylic acid, pelargonic acid, capric acid. Acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, isostearic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, elaidic acid, oleic acid, linoleic acid, linolenic acid, thioglycolic acid , Mercaptopropionic acid, octyl mercaptopropionic acid, benzoic acid, monochlorobenzoic acid, p-tert-butylbenzoic acid, dimethylhydroxybenzoic acid, 3,5-ditert-butyl-4-hydroxybenzoic acid, toluic acid, dimethylbenzoic acid Acid, ethylbenzoic acid, cumic acid, n Propylbenzoic acid, acetoxybenzoic acid, salicylic acid, monocarboxylic acids such as p-tertiary octylsalicylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Maleic acid, fumaric acid, citraconic acid, metaconic acid, itaconic acid, aconitic acid, thiodipropionic acid, phthalic acid, isophthalic acid, terephthalic acid, oxyphthalic acid, chlorophthalic acid and other divalent carboxylic acids or their monoesters or Monoamide compound, butanetricarboxylic acid, butanetetracarboxylic acid, hemimellitic acid, trimellitic acid, melophanoic acid,
Examples thereof include di- or triester compounds of trivalent or tetravalent carboxylic acids such as pyromellitic acid.

Further, examples of phenols constituting the above phenolate include phenol, cresol, xylenol, methylpropylphenol, methyl tert-octylphenol, ethylphenol, isopropylphenol, tert-butylphenol, n-butylphenol,
Diisobutylphenol, isoamylphenol, diamylphenol, isohexylphenol, octylphenol, isooctylphenol, 2-ethylhexylphenol, tertiary octylphenol, nonylphenol, dinonylphenol, tertiary nonylphenol, decylphenol, dodecylphenol, octadecylphenol, cyclohexylphenol, phenyl Examples include phenol.

By using an organic phosphite compound and / or an epoxy compound in combination with the composition of the present invention, an excellent synergistic effect is exhibited.

Examples of the organic phosphite compound include triphenyl phosphite, tris (2,4-ditert-butylphenyl) phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, Tris (mono, di mixed nonylphenyl) phosphite, diphenyl acid phosphite, 2,
2'-methylenebis (4,6-didaisanbutylphenyl) octylphosphite, diphenyldecylphosphite, phenyldiisodecylphosphite, tributylphosphite, tri (2-ethylhexyl) phosphite, tridecylphosphite, trilaurylphosphite , Dibutyl acid phosphite, dilauryl acid phosphite, trilauryl trithiophosphite,
Bis (neopentyl glycol) -1,4-cyclohexanedimethyldiphosphite, bis (2,4-ditert-butylphenyl) pentaerythritol diphosphite,
Distearyl pentaerythritol diphosphite, phenyl-4,4′-isopropylidene diphenol pentaerythritol diphosphite, tetra (C
_{1:12 5} mixed alkyl) -4,4'-isopropylidene diphenyl diphosphite, hydrogenated 4,4'-isopropylidenediphenol polyphosphite, bis (octylphenyl) bis [4,4'-n -Butylidene bis (2-tert-butyl-5-methylphenol)]-1,
6-hexanediol diphosphite, tetratridecyl 4,4'-butylidene bis (2-tert-butyl-5)
-Methylphenol) diphosphite, hexa (tridecyl) -1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butane triphosphite and the like.

The amount of the organic phosphite compound added is
It is preferably 0.01 to 5 parts by weight, and particularly preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the vinyl chloride resin.

The above-mentioned epoxy compounds usable in the present invention include epoxidized soybean oil, epoxidized linseed oil, epoxidized fish oil, epoxidized tall oil fatty acid ester, epoxidized beef tallow oil, epoxidized castor oil, epoxidized safflower. Oil, epoxidized linseed oil fatty acid butyl, epoxy methyl stearate, -butyl, -2-ethylhexyl or -stearyl, tris (epoxypropyl) isocyanurate, 3- (2-xenoxy) -1,2-epoxypropane, epoxidized Polybutadiene, bisphenol-A diglycidyl ether, vinylcyclohexene diepoxide, dicyclopentadiene diepoxide,
Examples thereof include 3,4-epoxycyclohexyl-6-methylepoxycyclohexanecarboxylate.

The amount of the above epoxy compound added is preferably 0.01 to 20 parts by weight, and particularly preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the vinyl chloride resin.

The composition of the present invention includes ester-based plasticizers such as phthalic acid ester-based plasticizers and adipic acid ester-based plasticizers or polyester-based plasticizers, phosphoric acid ester-based plasticizers, chlorine-based plasticizers, and other plasticizers. An agent or the like can be appropriately used according to the purpose.

In addition to the composition of the present invention, pentaerythritol, dipentaerythritol, sorbitol, mannitol, pentaerythritol or a stearic acid half ester of dipentaerythritol, bis (dipentaetasthritol) adipate, glycerin, tris (2).
-Hydroxyethyl) isocyanurate and other polyhydric alcohol compounds, and β-diketone compounds such as dehydroacetic acid, dibenzoylmethane, stearoylbenzoylmethane and ester-containing β-diketone compounds in combination with stabilizing aids to further improve the stability. Can be improved.

Other inorganic compounds such as synthetic talcites, calcium phosphate, magnesium phosphate and the like may be used in combination depending on the application.

If an ultraviolet absorber is added to the composition of the present invention, the photostability can be improved, and therefore it is possible to appropriately select and use them in combination according to the purpose of use.
These include benzophenone type, benzotriazole type,
Examples include salicylate type and substituted acrylonitrile type.

In addition, if necessary, the composition of the present invention may contain, for example, a crosslinking agent, a filler, a pigment, a foaming agent, an antistatic agent, an antifogging agent, an antiplateout agent, a surface treatment agent, a lubricant, and a flame retardant. , A fluorescent agent, an antifungal agent, a bactericidal agent, a photodegrading agent, a processing aid, a release agent, an antioxidant and the like can be included.

[0071]

EXAMPLES Next, the effects of the present invention will be specifically shown by examples, but the present invention is not limited by the following examples.

Example 1 Using the following formulation, a surface temperature of 180 ° C., a roll of 20 revolutions per minute, and a sheet thickness of 0.5 mm
As a result, a plate-out test was carried out from the stains on the roll surface after 15 minutes and 30 minutes. The evaluation method is
The manner of soiling of the roll surface is expressed in 10 stages, 1 represents a state in which there is no soiling, 1 is a state in which soiling is severe as the value is larger, and 10 is a state in which soiling is largest.

Further, a film having a thickness of 0.1 mm was prepared with a kneading roll, and a weather resistance test and an elongation residual rate test of the film by outdoor exposure were conducted.

The weather resistance test was conducted on outdoor exposure for 10 months and 2 months.
The surface condition of the film after 0 month is observed, and the evaluation criteria are shown in 10 levels, 1 being almost no discoloration and 10 being
Indicates a blackish brown state.

The elongation residual ratio is indicated by the residual ratio (%) in comparison with the elongation before exposure of the film after one year of outdoor exposure.

The results are shown in Table 1.

[Compound] parts by weight Vinyl chloride resin (polymerization degree 1450) 100 di-2-ethylhexyl phthalate 50 tricresyl phosphate 5 epoxidized linseed oil fatty acid octyl 2 Zn stearate 0.5 No 4 Zn salt (a = 2) , B = 0) 0.4 Ca stearate 0.3 No4 Ca salt (a = 2, b = 0) 0.9 tetra (C _12-15 mixed alkyl) bisphenol A diphosphite 0.8 sorbitan monopalmitate 1. 5 Methylenebisstearic acid amide 0.5 Octadecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate 0.1 Sample compound (Table-1) 0.4

[0078]

Comparative compounds 1 and 2 used in the comparative examples
Are shown in the following Chemical formulas 35 and 36, respectively.

[0080]

[Chemical 35]

[0081]

[Chemical 36]

Example 2 The same tests as in [Example 1] were conducted on the following formulations.

The results are shown in Table 2.

[Compound] parts by weight vinyl chloride resin (polymerization degree 1300) 100 di-2-ethylhexyl phthalate 50 tricresyl phosphate 5 bisphenol A diglycidyl ether 2 Zn stearate 0.5 Ba stearate 0.3 tetra ( C _12-15 mixed alkyl) bisphenol A diphosphite 0.8 polyoxyethylene sorbitan monolaurate 1.5 methylenebisstearic acid amide 0.5 compound I-6 0.4 sample compound (Table-2) 0.9

[0085] [Compound] parts by weight vinyl chloride resin (polymerization degree 1300) 100 di-2-ethylhexyl phthalate 50 tricresyl phosphate 5 bisphenol A diglycidyl ether 2 Zn stearate 0.5 Ba stearate 0.3 No 7 Ba salt ( a = 2, b = 0) 0.4 No12 Ba salt (a = 2, b = 0) 0.4 tetra (C _12-15 mixed alkyl) bisphenol A diphosphite 0.8 polyoxyethylene sorbitan monolaurate 1. 5 Surflon S-393 ^* 0.2 Ethylenebisstearic acid amide 0.5 Sample compound (Table-3) 0.4 * Asahi Glass Fluorosurfactant

[0086]

Example 4 Using the following formulation, kneading with a roll and then pressing were performed to prepare a sheet having a thickness of 1 mm, and a thermal stability test was performed in an oven at 190 ° C. A weather resistance test was conducted in the same manner as in [Example 1].

The results are shown in Table 4.

[Compound] parts by weight Vinyl chloride resin (polymerization degree 1300) 100 di-2-ethylhexyl phthalate 50 tricresyl phosphate 5 bisphenol A diglycidyl ether 2 Zn stearate 0.5 Ca stearate 0.3 tetra ( C _12-15 mixed alkyl) bisphenol A diphosphite 0.8 polyoxyethylene sorbitan monolaurate 1.5 Surflon S-393 ^* 0.2 ethylenebisstearic acid amide 0.5 compound I-6 0.4 sample compound (Table -4) 0.9 * Fluorine-based surfactant made by Asahi Glass

[0090]

From the above results, it is apparent that the triazine-type hindered amine compounds other than the present invention have markedly poor plate-out properties, and the ester-type hindered amine compounds have insufficient weather resistance. On the other hand, by using the triazine-type hindered amine compound of the present invention in combination with the phosphorus-containing metal salt, it is possible to provide a vinyl chloride resin composition for agriculture which has less plate-out and is excellent in weather resistance.

[0092]

The vinyl chloride resin composition for agriculture of the present invention has good plate-out properties and good weather resistance for a long period of time.

Claims (1)

Claim: What is claimed is: 1. A vinyl chloride resin comprising: (a) at least one hindered amine compound represented by the general formula (I) represented by the following chemical formula 1 and (b) the following chemical formula An agricultural vinyl chloride resin composition containing at least one phosphorus-containing metal salt represented by the general formula (II) and / or (III). [Chemical 1] (A represents a residue of a divalent to tetravalent organic polyvalent amine,
A is bonded to the triazine ring via a nitrogen atom,
The residue may have a nitrogen atom which is not bonded to the triazine ring. n shows 2-4. R ₁ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, or an oxygen free group. R ₂ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ) [Chemical 2] (In the formula, R ₃ and R ₅ represent an alkyl group having 1 to 30 carbon atoms, an aryl group, an arylalkyl group or an alkylaryl group, and R ₄ represents a hydrogen atom or a group represented by —OR _{3. 1} represents an alkaline earth metal, a zinc atom or an aluminum atom, a represents 2 or 3, b represents 0 or 1, a + b represents a valence of a metal, c represents 0 or 1, and M ₂ represents c = 0. Represents an alkaline earth metal or zinc atom, and c = 1 represents an aluminum atom.)