JPH0316363B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is directed to water-soluble high molecular weight synthetic polymers, and especially monomers, which contain unacceptably high amounts of impurities, such as excessive amounts of insolubles and/or unacceptably low viscosity and/or polymerization. The present invention relates to a method for producing water-soluble, high molecular weight synthetic polymers in which the present invention has a low rate of oxidation to produce a poor polymer. More specifically, the present invention provides residues In particular, by using cyclic compounds containing acrylamide and/or acrylic acid and/or 2-acrylamido-2-methyl-propanesulfonic acid which are essentially identical to the polymers prepared from pure monomers. and to producing polymers of salts thereof. Acrylamide is commonly prepared by hydration of acrylonitrile, which is well known in the art. This material is generally present in the reactor as a concentrated (40-60% by weight) solution. Acrylic acid is commonly produced by the oxidation of propylene, which is well known in the art. This material is generally supplied as a concentrated solution, ie 60% to glacial acrylic acid. 2-Acrylamido-2-methylpropanesulfonic acid is usually produced from acrylonitrile and sulfuric acid by the Ritter reaction. This material is often a solid powder that must be purified by recrystallization. For economic reasons, it is necessary to convert these products directly into water-soluble high molecular weight products. However, these monomer solutions or powders contain unknown impurities, apparently in the ppm range, although the exact amounts and types have not been determined to date.
When such monomers are polymerized, even with very low amounts of impurities, totally unacceptable polymers are often formed. In liquid-liquid polymerization, attempts to solve these problems have resulted in (a) very low drying temperatures; (b) excessive and expensive purification of the monomer solution; (c) very long polymerization times; (d ) addition of very large amounts of urea to the monomers; and/or (e) polymerization in very dilute solutions. However, each of these requires high amounts of energy or They were not satisfied with it because it was expensive. Attempts to solve these problems in water-in-oil emulsion polymerization have focused on (a) monomer purification; (b) very dilute solution polymerization; (c) use of different initiators; (d) urea and (e) the use of chain transfer agents. However, these were also not satisfied for the same or similar reasons as mentioned above. The object of the present invention is therefore to overcome these problems and to polymerize concentrated monomer solutions without expensive purification, ie crystallization. A further object of the present invention is to reduce the insoluble content in solution polymerized dry polyacrylamide and polyacrylic acid polymers to commercially acceptable amounts, ie, less than about 2% by weight. A further object of the present invention is to increase the standard viscosity of emulsion polymerized polyacrylamide and polyacrylic acid polymers to an acceptable degree, ie, to above about 4.5 centipoise and 5.0 centipoise, respectively. A further object of the present invention is to reduce the amount of crosslinked polymer formed during the polymerization and/or during drying or milling of acrylamide or acrylic acid or 2-acrylamido-2-methylpropanesulfonic acid polymers. . A further object of the present invention is to increase the rate of polymerization of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid type monomers. According to the invention, the formula A monomer solution of acrylamide and/or acrylic acid and/or 2-acrylamido-2-methylpropanesulfonic acid with a cyclic organic compound containing the residue of is provided. Preferably, the cyclic compound (hereinafter referred to as 1,3-dione) produces an improved product, preferably a commercially acceptable product, after the polymerization reaction of the monomers and/or increases the rate of polymerization. present in sufficient quantity to increase In the case of solution polymerization, this generally means an insolubles content of about 2% by weight or less. In the case of homoemulsion polymerization of acrylamide or acrylic acid, this means an insoluble content low enough that the standard viscosity is not intentionally reduced below about 4.5 centipoise. If a lower viscosity emulsion polymerization product is desired, 1,3-diones can be used to increase the reaction rate. In the case of homopolymerization of acrylic acid or 2-acrylamido-2-methylpropanesulfonic acid and its salts, this means an increase in the polymerization rate. According to the invention, the acrylamide or acrylic acid monomer is polymerized in an aqueous solution, optionally together with other ethylenically unsaturated monomers, and the resulting polymer is dried, provided that at least this drying is A method of making a water-soluble high molecular weight polyacrylamide or polyacrylic acid having a reduced insoluble content of about 2% or less is provided, the method comprising carrying out the process in the presence of a 3-dione. Furthermore, acrylamide or acrylic acid or 2-
A water-soluble high molecular weight polymer comprising emulsion polymerization of acrylamide-2-methylpropanesulfonic acid monomer, optionally with other ethylenically unsaturated monomers, in the presence of 1,3-dione. A method of manufacturing is provided. Furthermore, a method is provided for increasing the reaction rate of a homopolymer of 2-acrylamido-2-methylpropanesulfonic acid and its salts in the presence of 1,3-dione. These and other objects will become readily apparent from the detailed description below. The compounds used in this invention to make improved polymers have the formula is a cyclic organic compound containing the residue of These compounds are referred to as 1,3-diones, although the residue may be present in other positions within the compound. Examples of such 1,3-diones are 1,3-cyclopentanedione; 1,3-cyclohexanedione; 1,3-cycloheptanedione;
Cyclooctanedione; 1,3-cyclodecanedione; 5,5-dimethyl-1,3-cyclohexanedione; 5,5-diethyl-1,3-cyclohexanedione; 1,3,5-cyclohexantrone and its tautomer phloroglucinol (1,3,5-trihydroxybenzene); tetrahydronaphthalene-1,3-dione; barbituric acid; and substituted and unsubstituted derivatives of other such compounds. It is not limited to these. base

Tautomers of the above compounds having the formula are also included within the meaning of 1,3-dione as used in the present invention. These include metal enolates, including carbalkoxydimedone metal enolates, such as carbomethoxydimedone sodium enolate, carboethoxydimedone potassium enolate, and the like. Most preferably the 1,3-dione is 5,5-dimethyl-1,3-cyclohexanedione, also known as metone or dimetone. If the 1,3-dione is added to the monomer and the monomer is then polymerized, the 1,3-dione must not be a polymerization inhibitor. If it is an inhibitor, it must be removed from the monomer prior to polymerization. One such removal method is
The monomer solution is passed through a bed of activated carbon. Alternatively, in the case of solution polymerization, 1,3-dione may be added to the polymer gel prior to drying. Furthermore, if the 1,3-dione is not stable under the polymerization conditions, the polymerization conditions must be changed to avoid destabilization, or the 1,3-dione must be added to the polymer gel prior to drying. No. In some cases, detailed below, it has been found desirable to include about 20% by weight (based on monomer content) of urea or urea derivative with the 1,3-dione. Preferably 5-10% of urea itself is used. Suitable such compounds are disclosed in US Pat. No. 3,622,533, which is incorporated herein by reference. Urea can be added before, after or simultaneously with the 1,3-dione. Monomers that can be polymerized in the present invention include acrylamide, acrylic acid, and 2-acrylamide-2
-Methylpropanesulfonic acid and its salts.
Copolymers of these above-mentioned monomers or one or more monomers with other ethylenically unsaturated monomers suitable for producing water-soluble products can also be produced. Such other monomers include methacrylamide, salts of acrylic acid, methacrylic acid and its salts, methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, dimethylaminoethyl acrylate, Dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, hydroxyethyl acrylate,
Contains hydroxyethyl methacrylate, diethylaminoethyl methyl acrylate sulfate, styrene, acrylonitrile, 3-(methylacrylamido)propyl-trimethylammonium chloride, vinyl methyl ether, vinyl ethyl ether, alkali metal or ammonium salts of vinyl sulfonic acid, etc. However, it is not limited to these. All or part of the acrylamide portion of the polymer may be hydrolyzed. Polymerization methods that can be used in the present invention can be any of those commonly used for polymerizing such monomers. This includes in particular solution and emulsion polymerizations, but
Other techniques such as bead and suspension dispersion polymerization can also be used. Each of these specific polymerization systems are those commonly used. In the case of solution polymerization, this involves the use of one or more azo initiators in the presence or absence of a redox system and optionally the presence or absence of sequesterants, alcohols and diluents necessary for the polymerization reaction. . In the case of emulsion polymerization of water-in-oil emulsions, this involves using a water-in-oil emulsifier, an oil phase such as toluene, xylene or paraffin oil, and a free radical initiator. Since the invention is independent of the polymerization method used, reference is made to the literature for further details thereon. Furthermore, the amounts and each component will vary according to the monomers being polymerized and the process conditions under which the polymerization is carried out. The amount of 1,3-dione used in the present invention depends, at least in part, on the type of polymerization method, the type of monomer purification, and the degree of ripening of the monomer/1,3-dione composition. It has been found that it depends on the temperature at which the product is prepared and/or dried in the case, the presence and amount of urea, the amount of impurities in the concentrated monomer solution, and the residence time of the polymer at the highest temperature. Ta. As such, it is not possible to define an exact "amount that improves the polymer." However, generally it will range from about 0.001 to 2% (or more) by weight based on monomer, and more particularly in the case of emulsion polymerization and less in the case of solution polymerization. It's okay. In the case of emulsion polymerization,
Preferred amounts for unaged or room temperature aged solutions are about 0.3-1%, most preferably about 0.4-0.7% by weight. If accelerated aging (approximately 2 hours or more at approximately 50°C or higher) is used, the suitable amount is approximately 0.005 to 0.2
%, most preferably 0.007-0.1%. For solution polymerization, suitable amounts are about 0.03-0.4% and most preferably about 0.05-0.25% by weight. For solution polymerization of acrylamide and acrylic acid, (a) the concentrated monomer solution is purified by contacting with a cation exchange resin and/or activated carbon; (b) the drying temperature is above about 80°C, especially about 85°C. (c) as quickly as possible, i.e. without undue ripening;
It has proven advantageous to use monomer/1,3-dione solutions. Although it is unknown what is removed in step (a), it has been found that improved results can be obtained by step (a). Moreover, the advantages of the invention can also be realized by adding 1,3-dione not to the monomers, but rather to the resulting polymer gel before drying. This is not desirable in that it is very difficult to uniformly mix 1,3-dione into the gel. However, this indicates that the 1,3-dione is effective and is working in the drying stage of the solution polymerization. For emulsion polymerization, (a) aging the monomer/1,3-dione composition for about 5 days before use; or (b)
It has proven advantageous to age the composition at elevated temperatures (approximately 5 hours at 60-80° C.) for several hours before use. This ripening was found to enhance the effectiveness of the 1,3-dione. However, the advantageous effect is that based on the large amount of 1,3-dione, i.e.
By using 0.9-2% 1,3-dione,
I was able to materialize it without any maturity. Acrylamide or acrylic acid of the present invention/1,
In order to prepare the 3-dione solution, it has proven advantageous to dissolve the 1,3-dione in a concentrated monomer solution before dilution during the polymerization. Although there is essentially no difference in performance,
This is due to the increased time found required to dissolve the 1,3-dione into dilute solution. To prepare the 2-acrylamido-2-methylpropanesulfonic acid/1,3-dione solution, the two compounds can simply be mixed with water. Alternatively, the 1,3-dione may be introduced into the acrylonitrile or propylene from which the monomer was prepared. The following examples illustrate certain aspects of the invention and more particularly point out the advantages obtained by the invention.
However, the examples are merely illustrative and do not limit the invention except as indicated in the claims. All parts and percentages are by weight unless otherwise noted. Example 1 Preparation of an acrylamide/1,3-dione solution (a) 810.9 g of 51.3% aqueous acrylamide "as received" and 0.83 g of metone was added. The material was stirred magnetically in air for approximately 5 minutes to dissolve the metone. It contained 0.2% metone based on acrylamide monomer. (b) Prior to the addition of metone, the aqueous acrylamide was treated with a cation exchange resin (Amberlite IR from Rohm and Hass).
120] Step (a) was repeated except passing through the bed. (c) Prior to the addition of metone, the aqueous acrylamide was treated with (i) a cation exchange resin (Amberlite IR-
120) and then (ii) repeated the process of (a) except passing through a bed of activated carbon (Nuchar WV-L 8x30 mesh). (d) Other such solutions were prepared using various amounts of metone as shown in the examples below. Example 2 Solution polymerization of the monomer of Example 1(c) The monomer solution of Example 1(c) was solution polymerized as follows. It was placed in a 1 gallon polyethylene reactor and stirred magnetically. The following were then added with stirring: 2311.2 g deionized water 4.2 ml 2% aqueous ethylenediaminetetraacetic acid 3.2 ml 10% aqueous isopropanol 16.6 g aqueous sodium sulfate 4.2 g aqueous ammonium sulfate 20.8 g urea until the solution was complete. At that time, the pH of the reaction mass was adjusted to 3.0 with sulfuric acid. Nitrogen flow was then started at about 1000 ml/hour for 30 minutes while the reaction mass was warmed to about 35°C. Continuing this purging with nitrogen, add 13.3 ml of catalyst 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile) 0.0078 g/ml 2,2'-azobis(cyanovaleric acid) 0.02 g/ml ml
15.6ml of was introduced. Polymerization started within 10 minutes thereafter. The polymerization reaction was allowed to continue substantially adiabatically by isolating the reactor. The polymer experienced an exotherm of 29.8°C over approximately 2 hours. Then change this to approx.
Transferred to a curing oven at 70° C. and cured there for an additional 18 hours, yielding 3200 g of a hard gel product. The gel was then cut into strips and portions thereof were dried in a convection oven at temperatures of 90, 100 and 113±2° C. to a residual volatile content of 7-10%. Waring blender (Waring Blender)
The particle size was reduced in a vacuum and sieved to obtain a -20 US mesh particle size product. Example 3 Evaluation of the product of Example 2 To evaluate the product prepared in Example 2, the following was done: 0.3 g of the dried product at each temperature was dissolved in deionized water to give a concentration of 0.1 g. % polymer aqueous solution was prepared. The solution was passed through a 100 US mesh weight sieve to separate insoluble materials. The sieves were then washed with approximately 500 ml of deionized water at room temperature, dried overnight at 100°C, and the amount of insolubles was determined and reported as % insolubles. The percentage of residual volatiles is determined by measuring 1 g of sample to 100
Determined by measuring weight loss after drying at ~110°C for 2 hours. The degree of hydrolysis (% carboxyl) was determined by conductometric titration of carboxyl content in the polymer. In this case the lower the number, the better the product obtained for non-ionicity. The “as received” viscosity was determined by dissolving 0.3 g of the product in deionized water over 2 hours to make 300 g of an aqueous solution, passing it through a 100 US mesh sieve to separate insoluble material, and then passing it through a 100 US mesh sieve to separate the insolubles, then passing it through a 1 molar NaCl solution. add enough sodium chloride to prepare and
Determined by measuring Bruckfield viscosity using a UL adapter. This indicates the performance of the resulting product; the higher the number, the more desirable the final product. The results are shown in the table below along with the results of a comparative example produced in the same manner except without metone.
They clearly show that by adding 0.2% metone to the monomer, the "as-used" viscosity increases greatly and the % insolubles decreases from about 60% to less than 0.4%. There is.

Table: Example 4 The method of Examples 2 and 3 was repeated except that the amount of metone was reduced to 0.10% and 0.05%, respectively. The results were as follows.

Table: They show that the % insolubles increases as the amount of metone is reduced. Also, the amount
When it is 0.05% and the drying temperature is 100℃,
It can be seen that the amount of metone is insufficient to reduce the insoluble matter content to 2% or less. Examples 5-10 The methods of Examples 2 and 3 were repeated except that (1) the purification method and (2) the amount of metone were changed. The results are shown in the table.
As can be seen from the table, as the amount of metone was increased, an improved product was produced (as shown by increased "as-sourced" viscosity and decreased insolubles).

[Table] Examples 11-20 Treatment of monomers, presence and amount of urea and ketones,
The basic steps of Examples 2 and 3 were repeated, except that the catalyst system and PH, fixed percentage, maximum temperature, and time at maximum temperature were varied as shown in Table a.
For monomer treatment, "YES" indicates treatment with cation exchange resin as in Example 1b;
and "NONE" indicate prepared as in Example 1a. (NH ₄ ) ₂ SO ₄ % in Example 2
was 1%, Na ₂ SO ₄ % was 4%, and urea % was 5%. The data for the dry product is shown in Table b. To demonstrate that the 1,3-dione and/or urea can be omitted from the monomers and added to the gel to be present only during the drying stage, various post-additions were made as follows: Example 15 - post-addition of 0.1% metone and 10% urea Example 16 - post-addition of only 0.1% metone Examples 19 and 20 - post-addition of only 10% urea The dry product data for these are also shown in Table b. As can be seen from the data in Tables a and b, the effect of metone is independent of catalyst system or polymerization conditions, and benefits are obtained by using a combination of metone and urea.

【table】

[Table] Examples 21-28 Different untreated monomers, 27% solids, diethylenetriaminepentaacetic acid as sequestering agent, 2,2'-azobis(2-amidinopropane) hydrochloride and filtrate as catalyst. Ammonium sulfate/ferrous ammonium sulfate redox system, PH6.0, 0
The basic steps of Examples 2 and 3 were repeated except using a reaction initiation at 0.degree. C. and a residence time of 4 hours. Metone and urea usage and dry product data for products dried to about 12% volatiles at about 60-70°C are shown in the table below. As can be seen based on these polymerization conditions, metone alone produces an acceptable product (i.e., high as-available viscosity and less than about 2% insolubles), whereas urea alone produces It gave no such product.

TABLE Examples 29-38 Emulsion Polymerization of Acrylamide Metone was added to an aqueous acrylamide solution as in Example 1a with stirring for about 5 minutes.
The following steps were then used except that when the PH was 9, sodium hydroxide was added. To a suitable reaction vessel were added 2100.0 parts of acrylamide as a 50.47% aqueous solution and 850.0 parts of deionized water. To this solution are added 2.12 parts of disodium salt of ethylenediaminetetraacetic acid and 72 parts of hydrated ferric sulfate.
% _Fe2 ( _SO4 ) ₃ ) was added at 4.5 parts per 1000 parts _H2O . The pH of the resulting solution was adjusted to 5.0. This formed the aqueous monomer phase. The oil phase contains 90.0 parts of sorbitan monooleate,
AMSCO, a bright oily liquid sold by Union Oil Co. of California
Manufactured by dissolving in 1040.0 parts of OMS. The complete oil phase system was added to a suitable high speed homogenizer. The homogenizer was started and the monomer aqueous phase was slowly added to it to form an emulsion with a viscosity of 990 cps. The dispersed phase of the obtained emulsion is
It had a particle size of about 2.5 microns or less. The complete emulsion system was added to a suitable reactor with stirring. Then 70.0 ppm (based on monomer) of t-butyl hydroperoxide was added.
The resulting medium was purged with nitrogen gas to remove oxygen from the system. Sodium metasulfite was gradually pumped into the reactor over a period of 6 hours while stirring was continued and the reaction vessel was maintained at about 40°C, then at about 40°C.
100 ppm (based on monomer) was added. The resulting viscous emulsion showed 99.49% acrylamide loading. Stabilization of the polymer emulsion was achieved by adding 78.28 parts of a 30% aqueous sodium metasulfite solution. Polymerize this emulsion under conditions (40℃ for 60 minutes)
The remaining acrylamide was maintained at a low temperature to allow substantially complete reaction. 0.4% of this emulsion comprises sulfite which stabilizes the polymer system. To the resulting polymer emulsion was added 5.5% of a 70% solution of sodium bis(2-ethylhexyl)sulfosuccinate in AMSCO OMS as a converting agent mixture.
and 2.0% of the reaction product of 1 mole of octylphenol and 7.5 moles of ethylene oxide were added over 30 minutes. The resulting emulsion was kept at 40°C for an additional hour. After this time the product was homogeneous and particle-free. The dispersed polymer phase had a particle size of 2.5 microns or less. This standard viscosity was as shown in the table. The standard viscosity of the product obtained and the standard viscosities of other products by varying the amount of metone and the degree of ripeness are shown in the table below.

【table】

[Table] Examples 39-42 Preparation of copolymers The basic steps of Example 2 were repeated except that 10% by weight of acrylamide was replaced by equal weights of each of the following monomers: (a) Acrylic acid ( b) 2-Acrylamido-2-methylpropanammonium sulfonate (c) Dimethylaminoethyl methacrylate methyl sulfate. For (a) and (b), the PH was adjusted with sodium hydroxide. Comparable improved results were observed over the same copolymer without metone. Example 43 Preparation of 95/5 Acrylic Acid/Acrylamide Copolymer A stainless steel beaker was charged with 214 g of glacial acrylic acid (Rohm & Haas grade).
While stirring with a magnetic stirrer, 29% aqueous ammonia (technical grade) was added and the temperature was kept at 35° C. until the pH was 7.5 (approximately 1.5 hours). Distilled water was added to bring the total amount to 428 g. This solution was transferred to a glass beaker 1 and 1.07 g of metone (0.5% based on acrylic acid) was added while stirring. It dissolved in about 10 minutes. then 50% acrylamide
23 g was added and the monomers were emulsion polymerized according to the method of Examples 29-38. Standard viscosity was 5.7 centipoise. When the above process was repeated without metone, the standard viscosity was less than 2.9 centipoise. Example 44 Production of acrylic acid homopolymer The process of Example 43 was repeated to homopolymerize acrylic acid. It had a standard viscosity of 5.2 cps. When no metone was added, the standard viscosity was 2.5 cps. Examples 45-50 The process of Example 2 was repeated except that metone was replaced with the additives shown in the table below in the amounts shown below. The results of drying polyacrylamide at 90°C are also shown in the table. Carboethoxydimedone sodium enolate, which can obviously be an intermediate in the production of metone, gave the best results of the additives tested.

[Table] Example 51 1,3-Indanedione 0.05% by weight of 1,3-indanedione The method of Example 2 was repeated except that . The monomer did not polymerize because 1,3-intanedione was the inhibitor. On the other hand, the method of Example 15 was repeated, and 1,3-indanedione (0.2%) and urea (5.0%) were added at a later stage. That is, a polymer prepared without additives was dried in the presence of additives. The results of drying at 90°C were as follows. Viscosity as received: 2.9 Volatile % 7.4 Insoluble % 0.13, ie, the insoluble content was about 2% or less. Example 52 Meldrums Acid Meldrums Acid with varying PH and 0.103% of metone The method of Example 2 was repeated except that . Two polymerization reactions were conducted at PH4.5 and PH8.0. As is clear from the data below, higher PH values resulted in improved products. Therefore,
It appeared that the 1,3-dione must be stable and effective under the polymerization conditions if present during the polymerization and not just as a post-additive. The results of the product dried at 90°C were as follows: PH4.5 PH8.0 Viscosity as received 1.4 2.1 % volatile 9.9 2.1 % insoluble 60.0 38.5 Examples 53-64 Basic of Example 2 According to the following steps, the copolymers and homopolymers shown in the table were produced. A control polymer without metone was also prepared. In the table, AMD is acrylamide; AMPS is 2-acrylamido-2-methylpropanesulfonic acid; AN is acrylonitrile; and MAPTAC
is 3-(methylacrylamide)propyltrimethylammonium chloride. WNF means that the product was free and therefore the % insolubles could not be determined. Examples 57 and 58 contained 5% urea and were run at 10.3% solids. Examples 59-62 were conducted in the presence of urea and at 13% solids. Examples 63 and 64 were made in the absence of urea and redox systems, but with sodium hydroxide to adjust the PH. For 100% AMPS Examples 63 and 64, the average polymerization rate expressed as exothermic °C/min was determined adiabatically to be: Example Metone Rate 63 No 0.07%/min 64 Yes 0.14%/min ie the use of metone doubled the polymerization rate. Examples 53-62 demonstrate the effectiveness of using metone in reducing the amount of insoluble matter.

【table】

Table: Example 65 The process of Example 1(a) was repeated to prepare a solution of acrylamide containing 0.2% metone. The solution was left overnight and then passed through a bed of activated carbon (Nuchar WV-L 8x30 mesh). The resulting monomer was polymerized according to Example 2 above without the presence of metone. The polymer product was then dried at 90°C. This is the viscosity as received.
2.8, and the insoluble matter was only 2% or less.

Claims (1)

[Claims] 1. Acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof, or a mixture and formula thereof A composition comprising a cyclic organic compound containing a 1,3-dione residue. 2. The composition of claim 1, wherein the 1,3-dione is present in an amount of 0.001 to 2% by weight of the monomers. 3. A composition according to claim 1, comprising at least one further ethylenically unsaturated monomer which can be copolymerized to form a water-soluble copolymer. 4. A polymerizable composition according to claim 1, in which the 1,3-dione is not a polymerization inhibitor. 5 1,3-dione is 5,5-dimethyl-1,3
- cyclohexanedione or its tautomer 5,
The composition according to any one of claims 1 to 4, which is 5-dimethyl-tetrahydro-m-resorcinol. 6. Claim 1, wherein the 1,3-dione is selected from the group consisting essentially of 1,3-cyclohexanedione, phloroglycinol, barbituric acid, carbomethoxydimedone enolate, and carbethoxydimedone enolate. 4. The composition according to any one of items 4 to 4.