JPH0251206B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a method of manufacturing an insulated electric machine winding, and particularly to a method of manufacturing an insulated electric machine winding having excellent heat resistance. [Background of the Invention] In recent years, as electrical equipment such as rotating electric machines have become larger in capacity, smaller and lighter, and have harsher operating conditions, there has been a desire to develop insulated electrical machine windings with excellent heat resistance. . For this reason, insulating base materials and insulating varnishes with excellent heat resistance have been developed as constituent materials for insulated electric machine windings. Currently, glass-backed mica tape (JP-A-55-79641), heat-resistant film tape (JP-A-53-27801), or glass-backed fibrillated mica tape are used as insulating base materials. Insulating varnishes include varnishes whose main components are polyfunctional epoxides and polyfunctional isocyanates that can be converted into heat-resistant cured products by forming isocyanurate rings and oxazolidone rings upon heating.
No. 52-31000 (hereinafter referred to as insulating varnish) is used. By combining these insulating base materials and insulating varnishes, insulated electrical windings with heat resistance class C (220°C) have been obtained. Incidentally, when manufacturing insulated electric machine windings, an isocyanurate/osisazolidone forming catalyst has been added to the insulating varnish. However, when the catalyst is added to the insulating varnish, the curing of the insulating varnish proceeds gradually even at room temperature, and the service life of the insulating varnish is significantly shortened to about one day. This is disadvantageous in factory work where large quantities of insulating varnish are prepared and used repeatedly to insulate electrical windings.
It is also uneconomical. For this reason, a method has been proposed in which the catalyst is held in an insulating base material without adding the catalyst to the insulating varnish, and then the catalyst is impregnated with an insulating varnish that does not contain the catalyst and brought into contact with the catalyst within the insulating layer. (Special Publication No. 53-27801). The winding impregnated with the insulating varnish produced by this method is heated in exactly the same manner as the winding impregnated with the insulating varnish containing the catalyst to harden the insulating varnish, resulting in an insulated electrical winding with good heat resistance. Become. By the way, in order to facilitate the removal of hygroscopic moisture from the electric machine windings and the impregnation of the electric machine windings with the insulating varnish, the conductor wrapped around the insulating base material holding the catalyst is coated with 100 to 200 ml of insulating varnish immediately before impregnating it with the insulating varnish. It must be kept at a high temperature of 1 to 15 hours. At this time, the catalyst volatilizes from the insulating base material and the amount of catalyst in the insulating base material layer fluctuates, and it is difficult to adjust the curing conditions accordingly, so the characteristics of the manufactured insulated electrical windings do not vary. I didn't get it. Therefore, as a result of various studies on ways to improve the heat resistance of the isocyanurate/oxazolidone forming catalyst, the present invention was completed. [Object of the Invention] The object of the present invention is to eliminate the above-mentioned drawback that the isocyanurate/oxazolidone forming catalyst evaporates from the insulating base material layer and the catalyst amount fluctuates, and to produce an insulated electrical winding wire with excellent characteristics. The purpose is to provide a method that can be used. [Summary of the Invention] The main point of the present invention is to manufacture an insulated electrical winding wire by impregnating and curing a winding wire in which an organic acid salt of a transition metal is held in an insulating base material layer wound on a conductor in an insulating varnish. It's a method. In the present invention, examples of the polyfunctional epoxide include diglycidyl ether of bisphenol A, butadiene diepoxide, and 3,4-epoxyclohexylmethyl-(3,4-epoxy).
Cyclohexane carboxylate, vinyl cyclohexene dioxide, 4,4'-di(1,2-epoxyethyl) diphenyl ether, 4,4'-
(1,2-epoxyethyl)biphenyl, 2,2
-bis(3,4-epoxycyclohexyl)propane, diglycidyl ether of resorcinol, diglycidyl ether of phloroglucin, diglycidyl ether of methylphloroglucin, bis(2,
3-epoxycyclopentyl)ether, 2-
(3,4-epoxy)cyclohexane-5,5-
Spiro(3,4-epoxy)-cyclohexane-
m-dioxane, bis-(3,4-epoxy-6
-methylcyclohexyl)adipate, N,
N'-m-phenylenebis(4,5-epoxy-
Difunctional epoxides such as 1,2-cyclohexanedicarboximide, triglycidyl ether of para-aminophenol, polyallyl glycidyl ether, 1,3,5-tri(1,2-epoxyethyl)benzene, 2,2',4 , 4'-tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane, polyglycidyl ether of phenol formaldehyde novolac, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, etc. used. Among the polyfunctional epoxides mentioned above, polyglycidyl ethers of phenol formaldehyde novolak are particularly useful. Examples of polyfunctional isocyanates include methane diisocyanate, butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, transvinylene diisocyanate, propane 1,3-diisocyanate, and butane-1,4-diisocyanate. - diisocyanate,
2-butene-1,4-diisocyanate, 2-methylbutane-1,4-diisocyanate, pentane-1,5-diisocyanate, 2,2-dimethylpentane-1,5-diisocyanate, hexane-1,6-diisocyanate, heptane -1,
7-diisocyanate, octane-1,8-diisocyanate, nonane-1,9-diisocyanate, decane-1,10-diisocyanate, dimethylsilane diisocyanate, diphenylsilane diisocyanate, ω,ω'-1,3-dimethylbenzene diisocyanate, ω,ω'-1,4-dimethylbenzenediisocyanate, ω,ω'-1,
3-dimethylcyclohexane diisocyanate,
ω,ω'-1,4-dimethylcyclohexane diisocyanate, ω,ω'-1,4-dimethylbenzene diisocyanate, ω,ω'-1,4-dimethylnaphthalene diisocyanate, ω,ω'-1,
5-dimethylnaphthalene diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate,
1,3-phenylene diisocyanate, 1,4-
Phenyl diisocyanate, 1-methylbenzene, 2,4-diisocyanate, 1-methylbenzene-2,5-diisocyanate, 1-methylbenzene-2,6-diisocyanate, 1-methylbenzene 3,5-diisocyanate, diphenyl ether -4,4' diisocyanate, diphenyl ether-2,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-
1,5-diisocyanate, biphenyl-4,
4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,3'-dimethoxybiphenyl-4,4'-diisocyanate,
diphenylmethane, 4,4'-diisocyanate,
3,3'-dimethoxydiphenylmethane-4,4'-
Diisocyanate, difunctional isocyanate such as 4,4'-dimethoxydiphenylmethane-3,3'-diisocyanate, diphenylsulfide-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, polymethylene Polyphenyl isocyanate, triphenylmethane triisocyanate, tris(4-phenyl isocyanate thiophosphate), 3,3',4,4'-
3 such as diphenylmethanetetriisocyanate
A higher than functional isocyanate is used. Also usable are dimers and trimers of these isocyanates, or liquid isocyanates obtained by converting a portion of 4,4'-diphenylmethane diisocyanate into carbodiimide. The above-mentioned epoxides and isocyanates can be used alone or in combination of two or more. Preferably, 1.5% of the polyfunctional isocyanate is used per equivalent of the polyfunctional epoxide.
It is preferable to mix up to 50 equivalents. In order to adjust the gelation time of the insulating varnish and improve its storage stability, the insulating varnish is added before impregnating the winding wire.
It is desirable to add a storage stabilizer selected from active methylene compounds or π-electron acceptors in an amount of 1×10 ^-4 to 1% by weight. What is an active methylene compound?
C=O, -CH, _-NO2 , - described in -9169
A compound having a methylene group sandwiched between electron-withdrawing groups such as COOR, -COR, -SO ₃ R groups, etc. Specifically, for example, cyanoacetic acid, methyl cyanoacetate,
Cyanoacetic acid ether, α-cyanoacetamide, α
- Cyanoacetanilide, malonitrile, dinitromethane, etc. Furthermore, the π-electron acceptor is RSMulliken, described in Japanese Patent Publication No. 56-5455.
Jourmalde Chimie Physigue, Volume 61, 1964,
It is a compound that can form a charge transfer complex with an electron donor by charge transfer force as defined on page 21, and includes C=O-CN, -COOR, -COR, -NO ₂ ,
- Monocyclic, polycyclic, or heterocyclic aromatic compounds having two or more electron-withdrawing groups such as SO ₃ R, quinone compounds, and aliphatic hydrocarbons in which all hydrogen atoms are substituted with electron-withdrawing groups Refers to a group consisting of, specifically, for example, 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene, 2,
4,6-trinitrobenzoic acid ester, picric acid, picryl chloride, 2,4,6-trinitroanisole, 1,3,6,8-tetranitrocarbazole, 1,3,5-tricyanobenzene,
1,3,5-trimethoxycarbonylbenzene,
Anthraquinone, chloranil, 2,3-dichloro5,6-dicyano-P-benzoquinone, 2,3,
5,6-tetracyano-P-benzoquinone, 2,
3,5,6-tetracyano-P-benzoquinone,
Examples include tetracyanoquinodimethane and tetracyanoethylene. Periodic law of the present invention b, b, a, a,
Organic acid salts of at least one transition metal selected from groups a, a, and a include fatty acids such as copper, zinc, cadmium, titanium, zirconium, vanadium, chromium, molybdenum, iron, ruthenium, cobalt, and nickel, resin acids, and naphthenes. Salts with acids, especially octanoic acid and naphthenic acid. Among these transition metal organic acid salts, zirconium octoate, zirconium naphthenate, vanadium octoate,
Titanium octoate, titanium naphthenate, etc. are preferred. 0.005 for mixtures of polyfunctional epoxides and polyfunctional isocyanates.
It can be used in a range of ~10% by weight. Still more preferably the amount used is 0.01 to 2% by weight. In the present invention, by retaining the transition metal organic acid salt in the insulating base layer as a curing catalyst for the insulating varnish, the conventional drawback that the curing catalyst volatilizes from the insulating base layer can be solved, and further characteristics It is possible to obtain excellent insulated electrical machine windings. The insulated electrical winding produced according to the present invention comprises a catalyst that promotes a reaction in which the polyfunctional epoxide and the polyfunctional isocyanate component in the insulating varnish used in the present invention polymerize while forming a heterocycle, and the transition metal. In the presence of an organic acid salt adduct, an insulated electrical winding wire with excellent characteristics can be obtained. Examples of the heterocycle-forming catalyst in the present invention include tertiary amine compounds, N-substituted morpholine compounds, and imidazole compounds, and one or more of these can be used in combination. Tertiary amine compounds used as heterocycle-forming catalysts include trimethylamine, triethylamine, tetramethylbutanediamine, tetramethylpentanediamine, triethylenediamine, dimethylaminoethanol, dimethylaminopentanol, and triethanolamine. In addition, N-substituted morpholine includes N-methylmorpholine, N-ethylmorpholine, N-dodecylmorpholine, cyanoethylmorpholine, hexamethylenedimorpholine,
Examples include cyanoethylmorpholine and triazinoethylmorpholine. Furthermore, imidazole compounds include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-methyl-4-ethylimidazole, 1-butylimidazole, 1-
Propyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-
2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-azine-2-
Examples include methylimidazole, 1-azine-2-methylimidazole, and 1-azine-2-undecylimidazole. Among the above catalysts, it is particularly effective to use N-substituted morpholine compounds and imidazole derivatives as heterocycle-forming catalysts. At least one of the above catalysts can be used in an amount of 0.01 to 10% by weight based on the mixture of polyfunctional epoxide and polyfunctional isocyanate. Even more preferred amounts are in the range of 0.1 to 2% by weight. The adduct of the heterocycle-forming catalyst and an organic acid salt of a transition metal is prepared in a methanol or toluene solvent.
It can be produced by distilling off the solvent after refluxing for ~10 hours. The above additive is impregnated and retained in the insulating base material layer of the winding wire in advance. The amount is 0.05 to 5% by weight based on the amount of varnish impregnated into the winding wire.
It is desirable that the For this purpose, the above adduct is dissolved in an organic solvent to a concentration of 1 to 10% by weight.
It is preferable to use it as an adhesive, or to use it by dispersing or dissolving it in an adhesive such as a polyfunctional epoxide or silicone resin. A specific method of using the former organic solvent is to immerse an insulating base material in the solution to impregnate it and then wind it on a conductor, or to wind a wire formed by winding an insulating base material around a conductor as described above. There is a method of immersing it in a solution and attaching it. After impregnation, the organic solvent in which the adduct was dissolved is thoroughly removed. As a specific method for the latter, when adhering mica and glass woven fabric, add 1 to 10% of the additive to the adhesive.
There is a method of dispersing or dissolving mica to a concentration of % by weight and then adhering mica to glass woven cloth. It is also possible to add various additives to the solvent or adhesive, such as a surfactant that improves impregnation with varnish or a fixing agent that improves the properties of the adduct. The electric machine winding holding the additive is kept at a high temperature of 100 to 200°C for 1 to 15 hours under normal pressure or reduced pressure, then impregnated with the insulating varnish by a known method, and then heated at 90 to 250°C for 10 to 15 hours. The varnish is cured by heating for 50 hours to produce an insulated electrical winding. [Examples of the Invention] Next, the present invention will be explained with reference to Examples. Comparative Example 1 As shown in Fig. 1, fibrid mica (A mica manufactured by Nippon Aroma Co., Ltd.) and glass woven cloth were bound together with a silicone resin binder (12% by weight) on the surface of a preformed conductor 1. Insulating tape (0.13 mm thick) 2 was wrapped 4 times in a half overlap. In addition to the above binder, an imidazole compound (2PZ-CN manufactured by Shikoku Kasei Co., Ltd.) as a curing catalyst for impregnated varnish was attached at a rate of 1.0 g per 1 m ² of tape. A glass woven cloth (Nitto Boseki Co., Ltd., alkali-free tape ET05052mil thick) 3 to which the curing catalyst was attached at a rate of 0.5 g per 1 m ² was wrapped once on the layer of the above-mentioned fibrid mica tape. An electric machine winding was obtained. On the other hand, 100 parts by weight of bisphenol A diglycidyl ether (Dow Co., Ltd. DER332, epoxy equivalent weight 175), 400 parts by weight of liquid diphenylmethane diisocyanate (Bayer AG, Desmodyur CD, isocyanate equivalent weight 140) (isocyanate:epoxy equivalent ratio 5:1) ) was blended to prepare an impregnating varnish. Next, the electric machine winding was held at 150° C. for 5 hours in order to improve the removal of hygroscopic water and the impregnation of the insulating varnish. This electrical machine winding was vacuum impregnated at 40°C/0.1mmHg for about 5 hours, and then heated to 90°C.
The mixture was cured by heating at 160°C for 15 hours, then at 20°C for 5 hours. The breakdown voltage (BDV) of the obtained insulated electric machine winding was measured in oil using an electrode as shown in FIG. The result is the first
Write it down in the table. In FIG. 2, reference numeral 4 indicates an electrical insulating winding, 5 indicates a low voltage side electrode, and 6 indicates a high voltage side electrode. Examples 1 to 8 Example 1 uses zirconium octoate; Example 2 uses zirconium naphthenate; Example 3 uses vanadium octoate; Example 4 uses octane as a curing catalyst instead of the imidazole compound in Comparative Example 1. Titanium acid: Example 5 is titanium naphthenate: Example 6 is zinc octoate: Example 7 is cobalt octoate: Example 8
used manganese octoate. Other than that, an insulated electric machine winding was manufactured in the same manner as in Comparative Example 1,
BDV was measured. The results are shown in Table 1. Example 9 50% solution of hydroxyl group-containing silicone resin (KR-272 manufactured by Shin-Etsu Silicone Co., Ltd.: Silanol group content 1.0
%), 95% by weight, (non-volatile content) and addition-polymerized silicone resin (40 mol% monophenylsiloxane units, 15 mol% vinylmethylsiloxane units and
1.5% dicumyl peroxide based on the total amount of copolymer consisting of 45 mol% dimethylsiloxane units.
5% by weight (by weight), non-volatile content
A binder solution was prepared by adjusting the concentration to 50% with toluene. A curing catalyst, zirconium octoate, was added to this binder solution, and the unfired soft laminated mica sheet and glass cloth were laminated together, and the solvent was evaporated. The binder content in the obtained glass-backed laminated mica tape (insulating base material) is non-volatile.
The content was 20% by weight. The curing catalyst was added to the binder in an amount of 1.0 g per 1 m ³ of tape. The obtained insulating base material was cut to obtain an insulating tape with a width of 25 mm. Next, an insulated electrical machine winding was manufactured using this insulating tape in the same manner as in Comparative Example 1, and the BDV was measured.
The results are shown in Table 1. Comparative Example 2 Except that 2PZ-CN was used as a curing catalyst instead of zirconium octoate in Example 9,
An insulated electric machine winding was produced in the same manner as in Example 9,
BDV was measured. The results are shown in Table 1. Comparative Example 3 An insulated electrical winding was produced in the same manner as Comparative Example 1, except that polyimide film KAPON was used instead of fibrillated mica in Comparative Example 1.
I made a BDV. The results are shown in Table 1. Example 10 An insulated electrical winding was produced in the same manner as in Comparative Example 3, except that zirconium octoate was used as a curing catalyst instead of 2PZ-CN in Comparative Example 3, and the BDV was measured. The results are shown in Table 1. Examples 11 to 13 Insulated electrical windings were produced in the same manner as in Examples 6 to 8, except that 5.0×10 ^-3 weight % of cyanoacetic acid was added to the insulating impregnated varnish in Examples 6 to 8, respectively.
BDV was measured. The results are shown in Table 1. Example 14 Insulated electrical windings were produced in the same manner as in Example 6 except that 5.0×10 ^-3 % by weight of picryl chloride was added to the insulating impregnated varnish in Example 6,
BDV was measured. The results are shown in Table 1. Next, put some of the remaining insulating varnish used for vacuum impregnation into a Cardner-type viscosity measuring tube and seal it.
Place it in a constant temperature facility at 40℃ and measure the number of days (pot life) until the viscosity of the insulating varnish becomes 10 times the initial viscosity.
The results are shown in Table 1. The electrical winding wire, which is made by wrapping an insulating tape containing an organic acid salt of a transition metal as a curing catalyst on a conductor, does not lose its curing ability even when exposed to high temperatures. After impregnating and curing, its breakdown voltage shows a very good value, and the pot life of the remaining insulation varnish is greatly improved. Examples 15 to 22 As a curing catalyst instead of the imidazole compound in Comparative Example 1, Example 15 is an adduct of zirconium octoate and 2PZ-CN, and Example 16 is an adduct of zirconium naphthenate and 2PZ-CN. 17 is an adduct of vanadium octoate and 2PZ-CN, and Example 18 is an adduct of titanium octoate and 2PZ-
Adduct of CN, Example 19 is an adduct of titanium naphthenate and 2PZ-CN, Example 20 is an adduct of zinc octoate and 2PZ-CN, Example 21 is an adduct of cobalt octoate and 2PZ-CN, and Example 22 is an adduct of octanoic acid. with manganese
An insulated electric machine winding was manufactured in the same manner as in Comparative Example 1 except that 2PZ-CN was used, and a BDV was manufactured. The results are shown in Table 1. Example 23 Zirconium octoate and 2PZ- as curing catalyst
The same procedure as in Example 9 was carried out except that an adduct of CN was used. The results of BDV measurement are shown in Table 2. Comparative Example 4 Zirconium octoate in Example 9 and
As a curing catalyst instead of an adduct of 2PZ-CN
An insulated electric machine winding was manufactured in the same manner as in Example 9 except that 2PZ-CN was used, and the BDV was measured. The results are shown in Table 2. Example 24 An insulated electrical winding was produced in the same manner as in Comparative Example 3, except that an adduct of zirconium octoate and 2PZ-CN was used as a curing catalyst instead of 2PZ-CN in Comparative Example 3, and BDV was produced. It was measured. The results are shown in Table 2. Examples 25 to 27 Insulated electrical windings were produced in the same manner as in Examples 20 to 22, except that 5.0 x 10 ^-3 % by weight of cyanoacetic acid was added to the insulating impregnated varnish in Examples 20 to 22, respectively.
BDV was measured. The results are shown in Table 1. Example 28 Insulated electrical windings were produced in the same manner as in Example 20, except that 5.0×10 ^-3 % by weight of picris chloride was added to the insulating impregnated varnish in Example 20,
BDV was measured. The results are shown in Table 1. Next, put some of the remaining insulating varnish used for vacuum impregnation into a Gardner-type viscosity measuring tube and seal it.
Place it in a constant temperature facility at 40℃ and measure the number of days (pot life) until the viscosity of the insulating varnish becomes 10 times the initial viscosity.
The results are shown in Table 2. Electrical windings in which an insulating tape containing an adduct of an isocyanurate/oxazolidone catalyst and an organic acid salt of a transition metal as a curing catalyst is wound around a conductor do not deteriorate in curing ability even when exposed to high temperatures. After impregnating and curing the insulating varnish made of polyfunctional epoxide and polyfunctional isocyanate, its dielectric breakdown voltage showed a very good value, and Examples 1 to 14
shows better values than in the case of . Also, the pot life of the remaining insulating varnish is significantly improved.

【table】

〔Effect of the invention〕

As described above, according to the present invention, since volatilization of the curing catalyst from the insulating base material layer can be prevented, an insulated electric machine winding having excellent electrical insulation properties and heat resistance can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of an electrically insulated winding, and FIG. 2 is a block diagram of an electrode section for measuring BDV. 1... Conductor, 2... Insulating tape, 3... Glass woven fabric, 4... Electric insulation winding, 5... Low voltage side electrode,
6...High voltage side electrode.

Claims (1)

[Claims] 1. An organic acid salt of at least one transition metal selected from groups b, b, a, a, a, and a of the periodic law is held in an insulating base material layer wound on a conductor. 1. A method for manufacturing an insulated electrical winding wire, which comprises impregnating and curing a varnish containing at least a polyfunctional isocyanate and a polyfunctional epoxide. 2. The method for manufacturing an insulated electric machine winding according to claim 1, wherein the organic acid is octanoic acid or naphthenic acid. 3. A method for manufacturing an insulated electric machine winding according to claim 1 or 2, wherein the transition metal organic acid salt is at least one salt selected from zirconium, vanadium, and titanium. 4. In claim 1, the transition metal organic acid salt has an equivalent ratio of 0.005 to 10 based on the total weight of a mixture of polyfunctional epoxide and polyfunctional isocyanate in an equivalent ratio of 1:1.5 to 50. % by weight. 5 The insulating base material layer wound on the conductor contains (A) a heterocycle-forming catalyst and (B) the periodic law b, b, a, a,
It is characterized by impregnating and curing a varnish containing at least a polyfunctional isocyanate and a polyfunctional epoxide into a winding wire holding an adduct of at least one transition metal selected from Groups A, A, and an organic acid salt. A method of manufacturing an insulated electric machine winding wire. 6. The method for producing an insulated electrical winding wire according to claim 5, wherein the heterocycle-forming catalyst is at least one selected from a tertiary acine compound, an N-substituted morpholine compound, and an imidazole compound. 7 In claim 5, the heterocycle-forming catalyst has a content of 0.01 to 0.01 based on the total amount of the mixture of polyfunctional epoxide and polyfunctional isocyanate.
A method for manufacturing an insulated electrical winding wire, characterized in that the wire is 10% by weight. 8. The method for manufacturing an insulated electric machine winding according to claim 5, wherein the organic acid is octanoic acid or naphthenic acid. 9 In claim 5 or 8, the transition metal organic acid salt is at least one selected from zirconium, vanadium, and titanium.
A method for producing an insulated electrical winding wire, characterized in that the salt is a seed salt. 10 In claim 5, the transition metal organic acid salt is 0.005 to 10% by weight based on the total weight of the mixture of polyfunctional epoxide and polyfunctional isocyanate in an equivalent ratio of 1:1.5 to 50. %.