JPH0558008B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a polyurethane elastomer containing a carboxylic acid salt. [Prior Art] The reaction of carboxylic acids and polyols is well known. The best known reaction between these compounds is to form a polyester polyol, where the acid groups react with the OH groups in the polyol. Other reactions are also known. US Patent No.
No. 4,250,077 (Bonin et al.) teaches mixing olefinically unsaturated carboxylic acids with many types of polyols and then polymerizing the mixture with a free radical generator to produce graft polymers. . The preferred carboxylic acid (and the only acid used in the examples) is acrylic acid, which is homopolymerized by itself. It must be noted that this document does not teach the exact mechanism by which the "polymerization" reaction takes place. U.S. Pat. No. 4,365,024 (Frentzel) introduces polyoxyalkylene adducts into polyurethane foams by reacting them with esterified unsaturated dibasic acids containing 4 or 5 carbon atoms under free radical polymerization conditions. It has been shown to produce surfactants suitable for The mechanism of this reaction is called grafting. That is, the reaction product consists of a polyoxyalkylene adduct backbone to which "grafts" of unsaturated diesters are attached at intervals.
See column 4, lines 46-51 of this patent specification. The patent further states, ``Given that the unsaturated diesters of the present invention cannot be homopolymerized, as is well known, it is believed that this reaction mechanism involves the addition of a single diester unit to the polyoxyalkylene adduct backbone. "It has said. It teaches that these surfactants can be used in phenolic foams, polyisocyanurate foams, and polyurethane foams. U.S. Patent Application No. SN475785 (Frentzel) and SN475786 (Frentzel et al.) filed March 16, 1983.
filed in 1999, in which maleic acid, fumaric acid, itaconic acid or mixtures thereof are added to at least one polyhydroxy-containing mono- or polyether compound (e.g. polyether diol) in the presence of a peroxy free radical initiator. shows the production of carboxylic acid-containing mono- and polyether polyol addition products by reacting with polyols (or triols). These patent applications also disclose the preparation of polyurethane prepolymers and aqueous polyurethane dispersions from the carboxylic acid-containing mono and polyether polyol addition products described above. PROBLEM TO BE SOLVED BY THE INVENTION These selected carboxylic acid-containing mono- and polyether adducts have been found to be particularly advantageous for the production of ionomers and polyurethane elastomers. A single acid unit on the backbone provides sufficient sites to react with metal ions to create an ionomer, which in turn can be converted into a polyurethane elastomer. [Means for Solving the Problems] Accordingly, the present invention is directed to a method for producing a carboxylate-containing polyurethane elastomer, which method comprises: (a) at least one polyhydroxy polyurethane having an average molecular weight of 300 to 6500; a monoether or polyether compound containing an ethylenically unsaturated dicarboxylic acid selected from the group consisting of maleic acid, fumaric acid, itaconic acid and mixtures thereof in the presence of a free radical initiator of the peroxy type and reacting the polyhydroxy-containing monoether or polyether compound to acid in a weight ratio of 99:1 to 70:30 to form a carboxylic acid-containing monoether or polyether polyol adduct; Addition products are added in sufficient amounts to monovalent, bivalent,
neutralizing with a metal ion selected from the group of valent or trivalent metal ions, converting at least 10% of the carboxylic acid groups in the addition product to a metal salt; (c) the neutralized carboxylic acid; This is a method for producing a carboxylate-containing polyurethane elastomer, which comprises reacting a monoether or polyether polyol with an organic polyisocyanate to produce a carboxylate-containing polyurethane elastomer. These polyurethane elastomers can be used as plastic products and other useful products. 1. Preparation of Carboxylic Acid-Containing Polyether Polyol Addition Products Without limiting the invention, it is believed that this free radical initiated addition reaction occurs through a three-step mechanism. That is, it is explained by equations () to () below. Here, the monoether polyol or polyether polyol used is A and one of the selected acids is B.
Initiation: ROOR→2RO・ () Propagation: A+RO・→A・+ROH () A・+B→A−B・ () A−B・+A→A -B+A・ () A-B・+ROOR→A-B-OR+RO・ () A-B・+ROH→A-B+RO・ () Stop: 2RO・→ROOR () A・+A・→A-A () AB・+A・→A-B-A () AB・+AB・→ABBA () Tripropylene glycol (TPG) is the polyether polyol (A), maleic acid [cis-HOOCCH=CHCOOH] or fumaric acid [trans -HOOCCH=CHCOOH] is used as the acid (B), the above equations (), () and () can be written as the following equations (a), (a) and (a), respectively: As seen in equation (a) above, the carboxylic acid replaces the hydrogen atom on the carbon adjacent to the oxygen atom in the ether bond (C-O-C). For TPG as a polyether polyol, there are three other positions where the acid group could replace hydrogen. These are the other three carbon atoms adjacent to the ether oxygen atom. That is, it is theoretically possible for individual carboxylic acid groups to bind to all four positions on TPG. in fact,
Steric effects prevent the binding of many acid groups on such shorter polyether polyols. On longer polyether polyols, many carboxylic acid groups can be attached. Maleic acid, fumaric acid, and itaconic acid [HOOCCH ₂ C(=CH ₂ )COOH] are slightly ethylenically unsaturated dicarboxylic acids that can be used in the present invention because they do not homopolymerize. Free radical addition reactions with these are completed by removing hydrogen from other polyols [see equation () above] or from other sources of hydrogen atoms. Maleic acid and fumaric acid or a mixture of both are preferred from cost considerations. Polyhydroxy-containing monoether and polyether compounds suitable for the present invention contain two or more hydroxyl groups, one or more ether linkages (C-O-C) and 106
Includes any compound having a molecular weight of ~20,000. The compounds are commonly referred to as monoether polyols or polyether polyols. Two or more hydroxyl groups are required to react with the polyisocyanate to form the polyurethane prepolymer. Ether bonds are necessary for the generation of free radicals on adjacent carbon atoms. V.Malatesta and
J.Org.Chem. by JCScaiano, 1982, 47 ,
See "Absolute rate constants for the reaction of tert-butoxyl with ethers: the importance of stereoelectronic effects" on pages 1455-1459. Polyester polyols and other types of polyols that do not contain ether linkages could not be used in this reaction, but could be used as auxiliary polyols and analogs for reactions with polyisocyanates. In particular, suitable monoether polyols include diethylene glycol and dipropylene glycol. Because of their relatively short length, monoether polyols are usually not used alone, but in combination with polyether polyols. Suitable polyether polyols include various polyoxyalkylene polyols having 2 to 8 hydroxyl groups and mixtures thereof. These can be prepared by condensing an alkylene oxide or a mixture of alkylene oxides with a polyvalent initiator or a mixture of polyvalent initiators using random or stepwise addition according to well-known methods. Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, amylene oxide; aralkylene oxides such as styrene oxide and halogenated alkylene oxides such as trichlorobutylene oxide; tetrahydrofuran, epichlorohydrin and the like. Things can be mentioned. The most preferred alkylene oxides are ethylene oxide, propylene oxide or mixtures of these two oxides using random or stepwise oxyalkylation. The polyvalent initiators used to prepare the polyether polyol reactants include the following compounds and mixtures thereof: (a) ethylene glycol 1,3
- aliphatic diols such as propylene glycol, 1,2-propylene glycol, butylene glycol, butanediol, pentanediol and the like; (b) glycerin, trimethylolpropane, triethylolpropane, trimethylolhexane and the like; (c) Highly functional alcohols such as sorbitol, bentaerythritol, methyl glucoside and the like; (d) Polyamines such as tetraethylenediamine and (e) Diethanolamine, triethanolamine and the like. Alkanolamines like things. A preferred group of polyvalent initiators used to prepare the polyether polyol reactants consists of aliphatic diols and triols such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane and the like. The alkylene oxide monopolyinitiator condensation reaction is
Preferably, it is carried out in the presence of a catalyst such as KOH, which is well known in the art. To carry out this reaction, a sufficient proportion of alkylene oxide is used.
Try to give a final polyol product with an average molecular weight of 300-6500. Thereafter, the catalyst is preferably removed, leaving behind a polyether polyol that can be used to prepare the hydroxyl-terminated prepolymers of the present invention. Preferred polyether polyols are derived from diols, triols and mixtures thereof.
The most preferred polyether polyols for this invention are polyoxyethylene diols and triols, polyoxypropylene diols and triols, block and random polyoxyethylene-polyoxypropylene diols and triols, and mixtures thereof, having an average molecular weight of 300 to 6500. be. The monoether and polyether polyol reactants of the present invention may be reacted with diacids or anhydrides to form polyester polyether polyols prior to the addition reaction of the present invention [step (a) above]. can. Therefore, a polyester polyether polyol is produced having carboxylic acid groups spaced apart from each other in the molecule. Any peroxy type free radical initiator can be used in the present invention. Other types of initiators are not suitable for the present invention. Typical peroxy-type free radical initiators are hydrogen peroxide and dibenzoyl peroxide,
Acetyl peroxide, benzoyl hydroperoxide, t-butyl hydroperoxide, di-peroxide
t-butyl, lauroyl peroxide, butyryl peroxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, diacetyl peroxide, dialphacumyl peroxide, dipropyl peroxide, diisopropyl peroxide, isopropyl-t-butyl peroxide,
Butyl peroxide-t-butyl peroxide, dilauroyl peroxide, difuroyl peroxide, ditriphenylmethyl peroxide, bis(P-methoxy-benzoyl) peroxide,
P-monomethoxybenzoyl peroxide, rubrene peroxide, ascaridol, t-butyl peroxybenzoate, diethyl pen oxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decalin hydroperoxide, α-methylbenzyl hydroperoxide, α-methyl-α-ethylbenzyl hydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide,
diphenylmethyl hydroperoxide, 2,5-
Di-methyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1,1-bis(t-
butyl-peroxy)cyclohexane and t-
Includes organoperoxides and hydroperoxides such as butyl perpenzoate. As mentioned above, the weight ratio of all monoether polyether(s) and polyether polyol(s) used to unsaturated dicarboxylic acid is:
It should be between 99:1 and 70:30. of the polyol
Using less than about 1 part by weight of the acid per 99 parts by weight;
The properties of the polyol remain largely unchanged, making this reaction meaningless for many applications. of the polyol
When using more than 30 parts by weight of the acid per 70 parts by weight,
A significant portion of the acid often does not react with the polyol because not enough active sites are present. Preferably, this weight ratio is about 95:5 to 80:20. Besides the selected reactants, peroxy-type initiator and weight ratios as described above, the other reaction conditions at this stage are also not specific to the invention, and the process of the invention is not amenable to any particular conditions. Should not be limited. The reaction is preferably carried out at a temperature of about 25°C to 150°C, more preferably the reaction temperature is in the range of about 80°C to 130°C. The reaction temperature should be high enough to activate the peroxy-type free radical initiator for this reaction. In some cases,
It may be desirable to add a free radical promoter, such as a redox catalyst, to accelerate the reaction. The reaction time mainly depends on the reaction temperature employed, with a suitable reaction time of about 30
~600 minutes. The reaction is controlled by monitoring the disappearance of maleic acid, fumaric acid or itaconic acid in the reaction mixture by conventional analytical methods. Generally, this reaction can be carried out without a solvent. However, in some cases it may be desirable to use a solvent. For example, when using highly viscous polyether polyols, it may be desirable to dilute the reaction mixture with water or other solvent to facilitate the reaction. Furthermore, the present invention does not particularly require a reaction pressure above or below atmospheric pressure. Atmospheric pressure is preferred to avoid the expense of special reaction vessels. Free radical initiated reactions in the present invention can be carried out under conditions well known as being suitable for free radical polymerization. The reaction is carried out under an inert atmosphere (e.g., a nitrogen blanket) with the reactants, initiator(s), and optional free radical promoter(s), and solvent at a temperature of about 25°C to 150°C until the reaction is complete. ) is advantageously carried out. The initiator(s) and optionally the promoter(s) and solvent may be added at the beginning of the reaction or may be added in portions at intervals during the reaction. Similarly, the unsaturated acid reactant(s) and monoether polyol(s) or polyether polyol(s) reactants may be mixed at the beginning of the reaction or may be brought together gradually as the reaction progresses. The addition products produced by this reaction are generally water-insoluble. 2. Neutralizing the addition product with metal ions to produce a metal salt (ionomer) As described above, the produced addition product is neutralized with at least one of the carboxylic acid groups in the addition product according to the present invention.
Neutralize to convert 10% to metal salts (e.g. −COO ⁻ Na ⁺ ). The presence of these salt groups increases certain physical properties of the polyurethane elastomers made therefrom, such as hardness, tensile strength and flexural modulus, but does not appreciably reduce elongation. Therefore, the obtained polyurethane elastomer is
Desired physical properties can be achieved without using additional amounts of chain extenders and polyisocyanates. Suitable metal ions for producing the ionomer in the present invention are those of the periodic table 1a, 2a, 8, 1b.
and monovalent, divalent, and trivalent ions of group 2b metals (Handbook of Chemistry and
Physics, Chemical Rubfer Publishing
Co., 63rd Ed. (see inside cover). Suitable monovalent metal ions are Na ⁺ , K ⁺ , Li ⁺ , Ag ⁺ , Hg ⁺ and Cu ⁺ . Suitable divalent metal ions are Mg ⁺² ,
Ca ⁺² , Ba ⁺² , Cu ⁺² , Pd ⁺² , Pt ⁺² , Cd ⁺² , Hg ⁺² ,
They are Fe ⁺² , Co ⁺² , Ni ⁺² and Zn ⁺² . Appropriate 3
The valent metal ion is Fe ⁺³ . Preferred metal ions are industrially alkali metal and alkaline earth metal ions, especially Na ⁺ , K ⁺ , Ca ⁺² and
Mg ⁺² is preferred in view of its reaction rate. Ionomers containing more than one metal ion can also be used. Metal ions are obtained by adding metal-containing compounds to an aqueous solution;
It can be produced by dissociating metal cations from anions. Suitable anions include hydroxide, oxide, formate, acetate, nitrate, carbonate, and bicarbonate. Other metal-containing compounds that exhibit some degree of ionization in water can also be used. Hydroxide and oxide anions are preferred because they do not produce impurities that require separation from the aqueous solution. The amount of metal ion should be sufficient to convert at least 10% by weight of the carboxylic acid groups to metal salts. This is believed to be approximately the minimum amount of salt groups required to effect a significant change in the properties of the adduct in most applications. More preferably, at least a majority (ie, about 50% or more) of the carboxylic acid groups are converted to metal salt groups. In some applications, virtually all (i.e.
More preferably, the carboxylic acid groups are converted by at least 95%). This neutralization step can also be accomplished by simply adding the unneutralized addition product produced in step (a) to an aqueous solution containing the desired dissociated metal-containing compound, allowing neutralization to occur in situ. can. 3 Preparation of Polyurethane Elastomers The carboxylic acid-containing monoether and polyether polyol adducts prepared as described above are used to produce polyurethane elastomer products. These elastomers are made by reacting these metal salt compounds with at least one organic polyisocyanate under conventional and well-known reaction conditions. Suitable organic polyisocyanates include any aromatic, cycloaliphatic, aliphatic diisocyanates and higher polyisocyanates. Diisocyanates are a preferred class of polyisocyanates. Suitable aliphatic diisocyanates include hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-tetramethylene diisocyanate and 1,10-decamethylene diisocyanate. Suitable aromatic diisocyanates are toluene-2,4- or 2,6-diisocyanate (also known as mixtures or each TDI), 1,5-naphthalene diisocyanate, 4-methoxy-1,3
-phenylene diisocyanate, 4-chloro-
1,3-phenylene diisocyanate, 2,4'-
Diisocyanato diphenyl ether, 5,6-dimethyl-1,3-phenylene diisocyanate,
2,4-dimethyl-1,3-phenylene diisocyanate, 4,4'-diisocyanatodiphenyl ether, benzidine diisocyanate, 4,4'-
Diisoyanatodibenzyl, methylene-bis(4
-phenyl-isocyanate) (also known as MDI) and 1,3-phenylene diisocyanate. In addition to the presence of these two reactants, the other reaction parameters for this polyurethane production process are also not critical, and the invention should not be limited to any particular conditions for carrying out this process. do not have. For some applications, it may be desirable to add one or more chain extenders. These include any compound containing two active hydrogen-containing groups and having a molecular weight of 18-200. Specific examples include diols, diamines, hydrazine, dihydrazine and the like. A preferred diol is ethylene diol. Other suitable compounds include ethylenediamine, isophoronediamine, diethylene glycol and 1,4-butanediol. The rate of reaction between ionomer(s) and polyisocyanate(s) can be increased by using commonly known polyurethane forming catalysts. These include tertiary amine catalysts and organometallic compounds such as organomercury and organotin compounds. However, the use of such catalysts is not critical to the invention. Additionally, plasticizers, pigments and fillers such as carbon black, silica and clay can be incorporated into these urethanes. The ratio of isocyanate (NCO) groups to hydroxyl (OH) groups in the reactants is preferably from about 0.9:1 to about 1.2:
1, more preferably about 1:1 to 1.05:1. The preferred reaction temperature for producing the elastomer is about 25°C to 150°C, more preferably about
It ranges from 25℃ to 130℃. In this polyurethane elastomer production step it is advantageous to add additional compounds which also react with isocyanate groups. These additional compounds include polyether polyols, polyester polyols, and other conventional compounds known to react with polyisocyanates to form polyurethanes. The carboxylate-containing polyurethane elastomer of the present invention can be used as automobile structural parts, furniture parts, sports equipment, and the like. [Examples] The following examples are provided to further illustrate the present invention, and parts and percentages are by weight unless otherwise specified. Example 1 Preparation of carboxylic acid-containing polyether polyol addition product with fumaric acid A three-necked flask was charged with fumaric acid (140 g) and polyether polyol (3500 g). The mixture was heated to 105° C. under nitrogen atmosphere while stirring. Free radical initiator, 2,5-dimethyl-2,5
-Bis(2-ethylhexanoylperoxy)hexane was added in 3g portions every 1.5 hours. A total of 27 g of initiator was added within 13 hours before the fumaric acid was completely reacted. The amber liquid product was cooled to room temperature and used without purification to make various metal salts (see Examples 2, 3 and 4 below). As a result of IR analysis of this carboxylic acid-containing polyether polyol,
There was no double bond of fumaric acid at 1650 cm ^-1 , indicating that fumaric acid had completely reacted. [Note] “POLY-G 85-29-2” (product name) manufactured by Olin Company of Stanford, Connecticut. This polyether polyol is a triol with an average molecular weight of 6,400 and is prepared by block reacting a glycerin initiator first with propylene oxide and then with ethylene oxide. Example 2 Preparation of Calcium Salt A three-necked flask was charged with the carboxylated polyol of Example 1 (2000 g), CaO (36.7 g) and water (100 g). 90 while stirring the mixture.
heated to ℃. As measured by IR analysis,
After 3 hours the conversion of the acid to the calcium salt was complete. Water was removed in vacuo to obtain a liquid product. Example 3 Preparation of Magnesium Salt In a three-necked flask, add the carboxylated polyol of Example 1 (2000 g), MgO (24 g) and water (100 g).
I put it in. After 3 hours at 90°C, IR analysis confirmed complete conversion of the acid to the Mg salt. The water was removed under vacuum. Example 4 Preparation of Zinc Salt A three-necked flask was charged with the carboxylated polyol of Example 1 (2000 g), ZnO (53.3 g) and water (100 g). After 3 hours at 90°C, IR analysis confirmed the reaction was complete. The water was removed under vacuum. Example 5 Production of RIM molded product Polyether polyol (172g) used in Example 1, ethylene glycol chain extender (28g),
Organomercury catalyst (1g), silicone deaerator (2 drops) and polymeric isocyanate (147.3g)
were weighed in that order and placed in a large beaker. Stir the contents for 1 minute, degas in vacuo, and store 1/8″ x 6″ x
It was poured into a 6″ mold and heated to 135°C. After curing at 135°C for 24 hours, the solid product was removed from the mold and subjected to physical property tests. The results are shown in the table. "Cocure44" (trade name), available from Cosun Chemical Co., 400 14th Street, Waterford, NY 12188; "SF-1080" (trade name), available from GE Silicone Products Department, Laporte, TX; Polymer MDI, “Isonate 143L” (trade name), commercially available from Appdition, a polymer chemical division, Examples 6 to 9 Example 5 except that the type of polyol, the weight of ethylene glycol, and the weight of isocyanate were changed.
The procedure was repeated. The results are shown in the table. These results demonstrate that using the indicated ionomer, the hardness and flexural modulus are increased compared to Example 5 without the use of additional amounts of ethylene glycol and isocyanate. This means that by using less chain extender and isocyanate, the cost of manufacturing products with these improved physical properties is reduced. Examples 8 and 9 differ from Examples 5 and 6 in that the relative amounts of reagents were varied. Examples 8 and 9 give moldings with relatively high hardness and strength.

【table】

[Table] Example 10 Preparation of TDI molding Polyether polyol (150 g) used in Example 1, mercury catalyst (1.1 g), silicone deaerator (2 drops) and 2,4- and 2,6-toluenediamine diisocyanate (TDI) (6.6 g) were added in that order to a large beaker. The contents were stirred for 1 minute, degassed and poured into 1/8" x 6" x 6" molds.
After curing at 85 °C for 24 h, the solid sample was removed and
It was subjected to physical property tests. The results are shown in the table. [Note] “Cocure44” (trade name), commercially available from Cosun Chemical Co., 400 14th Street, Karlscht, NJ07072; “SF-1080”, commercially available from GE Silicone Products Department, Waterford, NY12188; Trade name) Examples 11-13 The procedure of Example 10 was repeated except that the type of polyol and the weight of each component were changed. The results are shown in the table. These results demonstrate that the indicated ionomer increases the hardness and tensile strength compared to Example 10 without the use of chain extender and additional isocyanate.
This shows that the elongation remains almost unchanged.

【table】

Claims (1)

[Scope of Claims] 1(a) At least one polyhydroxy-containing monoether or polyether compound having an average molecular weight of 300 to 6500 selected from the group consisting of maleic acid, fumaric acid, itaconic acid and mixtures thereof. an ethylenically unsaturated dicarboxylic acid in the presence of a peroxy-type free radical initiator and at a weight ratio of the polyhydroxy-containing monoether or polyether compound to the acid of 99:1 to 70:30. forming a carboxylic acid-containing monoether or polyether polyol adduct; and (b) adding a sufficient amount of the formed adduct to a monovalent group 1a, 2a, 8, 1b and 2b of the Periodic Table. ,2
neutralizing with a metal ion selected from the group of valent or trivalent metal ions, converting at least 10% of the carboxylic acid groups in the addition product to a metal salt; (c) the neutralized carboxylic acid; 1. A method for producing a carboxylate-containing polyurethane elastomer, which comprises reacting a monoether or polyether polyol with an organic polyisocyanate to produce a carboxylate-containing polyurethane elastomer. 2. The polyhydroxy-containing monoether or polyether compound can be converted into polyoxyethylene diol, polyoxyethylene triol, polyoxypropylene diol, polyoxypropylene triol, block and random polyoxyethylene-polyoxypropylene diol and triol, and mixtures thereof. The method of claim 1, wherein the method is reacted with an acid selected from the group consisting of maleic acid and fumaric acid at a temperature of about 80°C to 130°C. 3 Metal ions as Na ⁺ , K ⁺ , Li ⁺ , Ag ⁺ , Hg ⁺ ,
Cu ⁺ , Mg ⁺² , Ca ⁺² , Ba ⁺² , Cu ⁺² , Cd ⁺² , Hg ⁺² ,
Fe ⁺² , Co ⁺² , Ni ⁺² , Zn ⁺² , Pd ⁺² , Pt ⁺² and
A method according to claim 1, wherein the method is selected from the group consisting of Fe ⁺³ . 4 neutralizing the addition product with a sufficient amount of neutralizing agent;
4. The method of claim 3, wherein substantially all of the carboxylic acid groups are converted to metal salts. 5. The method of claim 1, wherein the organic polyisocyanate is at least one aromatic, cycloaliphatic and aliphatic diisocyanate. 6 The molar ratio of NCO to OH groups is approximately 0.9:1 to 1.2:1
The method according to claim 1.