KR20190042190A - Method for preparing polythiourethane compound having improved process - Google Patents

Abstract

The present invention relates to a manufacturing method of a polythiourethane-based compound having improved processability. The manufacturing method controls the initial reactivity of a composition slowly by performing a defoaming step and a stabilization step of a polymerizable composition at low temperature, thereby being able to inhibit the occurrence of bubbles during mold injection, which is caused by the increase in viscosity of the polymerizable composition. Furthermore, it is possible to prevent defects such as striae, efflorescence and the like caused by non-uniform curing, since a catalytic activity is maintained smoothly at a certain temperature or higher. In addition, by being completely cured when a final curing process is ended, problems of deterioration of thermal and mechanical properties caused by being uncured can be solved, thereby being usefully used for manufacturing various plastic lenses such as spectacle lenses, camera lenses and the like.

Description

METHOD FOR PREPARING POLYTHIURETHANE COMPOUND HAVING IMPROVED PROCESS [0002]

The present invention relates to a process for producing a polythiourethane-based compound having improved processability and a polythiourethane-based plastic lens obtained from the process.

Plastic materials of various resins are widely used as optical materials such as eyeglass lenses and camera lenses because they are lightweight and easily breakable and excellent in dyeability compared with optical materials made of inorganic materials such as glass.

Generally, a polythiourethane-based compound is produced by casting polymerization in which a polymerizable composition is injected into a mold and heat-cured. At this time, the polymerization reaction is carried out over several hours to several hours while slowly raising the temperature from a low temperature to a high temperature. Here, it is very important to secure sufficient time to mold, that is, sufficient pot life (pot life) to improve workability. Further, in order to sufficiently draw the resin properties, it is necessary to complete the polymerization. In order to complete the polymerization, a method of using a catalyst having a strong polymerization activity or increasing the amount of the catalyst may be mentioned. In order to obtain stable polymerizability, it is important to secure a stable port life even in a different lot. If the pot life varies from lot to lot, polymerization deviations may occur, which may affect the quality stability of the resin.

Generally, a halogen tin catalyst is most commonly used in accordance with the conditions described above, and recently, a method of using an amine catalyst has also been known (Korean Patent Nos. 10-1207128 and 10-0191067) .

However, when a halogen-tin-based catalyst, an amine-based catalyst, or the like is used, problems such as appearance problems of bubbles, sparrows, whiteness, etc. due to process conditions such as composition, viscosity of the composition, The problem of thermal and mechanical properties is still not solved.

Korean Patent No. 10-1207128 Korea Patent No. 10-0191067

Therefore, the embodiment uses a halogen tin-based catalyst to appropriately control the structure and content of the catalyst and appropriately maintain the viscosity of the composition and the activity of the catalyst by carrying out a partial process at a low temperature to solve the above problems And a method for producing a polythiourethane compound for a plastic lens.

The Examples disclose that a polymerizable composition comprising a polythiol compound, a polyisocyanate compound, and a halogen tin catalyst is defoamed at a temperature of 5 to 15 DEG C and a pressure of 0.1 to 10 torr for 0.5 to 3 hours, And a time-stabilizing step of reacting the polythiourethane-based compound with the polythiourethane-based compound.

The example provides the polythiourethane-based compound obtained by the above-mentioned production method.

An embodiment provides a plastic lens molded from the polythiourethane-based compound.

The process for preparing a polythiourethane compound according to an embodiment can control the initial reactivity of the composition slowly by performing the defoaming and stabilization steps of the polymerizable composition at a low temperature to inhibit bubble formation during mold injection caused by viscosity increase of the polymerizable composition can do. Further, when the temperature is higher than the predetermined temperature, the catalytic activity is maintained smoothly, and defects such as fogging, whitening, and the like caused by unevenness in hardening can be prevented. Further, since the problems of thermal and mechanical property deterioration caused by uncured curing can be solved when the final curing process is completed, it can be usefully used for manufacturing various plastic lenses such as spectacle lenses and camera lenses.

The Examples disclose that a polymerizable composition comprising a polythiol compound, a polyisocyanate compound, and a halogen tin catalyst is defoamed at a temperature of 5 to 15 DEG C and a pressure of 0.1 to 10 torr for 0.5 to 3 hours, And a time-stabilizing step of reacting the polythiourethane-based compound with the polythiourethane-based compound.

According to the above production method, a halogen tin-based catalyst can be used as a catalyst, and specifically, a compound represented by the following formula 1 can be used as a catalyst:

 [Chemical Formula 1]

Wherein, X is halogen, Y is a substituted or unsubstituted C _1-10 alkyl, C _1-30 alkoxy, C _4-30 cycloalkyl, C _4-30 heteroaryl, C _6-30 aryl, C _{1- 30} is an alkyl-substituted C _6-30 aryl or C _6-30 aryloxy, n and m are each independently an integer of 0 to 4, an integer from 1 to 4, or an integer of 1 to 3, n + m = 4, and when n is 2 or more, X is the same as or different from each other, and when m is 2 or more, Y is the same as or different from each other.

Specifically, X is Cl, and Y may be substituted or unsubstituted C _1-10 alkyl, phenyl or phenyl substituted with C _1-30 alkyl.

More specifically, X is Cl, and Y may be substituted or unsubstituted C _1-10 alkyl.

The compound of Formula 1 may be, for example, selected from the group consisting of dimethyl tin dichloride, dibutyl tin dichloride, butyl tin trichloride, diphenyl tin dichloride, tetrabutyl tin chloride, di-t-butyl tin dichloride, triphenyl tin chloride, tricyclohexyltin chloride , Phenyltin trichloride, methyl tin trichloride, or mixtures thereof, and specifically may be dimethyl tin dichloride or dibutyl tin dichloride.

The compound represented by Formula 1 may be used in an amount of 0.001 to 0.1 parts by weight, 0.002 to 0.05 parts by weight, or 0.03 to 0.04 parts by weight based on 100 parts by weight of the polymerizable composition. Within the above range, it is advantageous to keep the polymerization rate at a proper level to improve the appearance of the lens and uniformly maintain the overall physical properties of the lens.

The production method of the polythiourethane compound will be described in detail as follows.

The polythiourethane-based compound is prepared by: (1) preparing a polymerizable composition comprising a polythiol compound, a polyisocyanate compound, and a compound represented by Formula 1; (2) defoaming the polymerizable composition; (3) stabilizing the defoamed polymerizable composition, and (4) polymerizing the stabilized polymerizable composition.

Specifically, the method for producing the polythiourethane-based compound comprises the steps of (1) preparing a polymerizable composition comprising a polythiol compound, a polyisocyanate compound, and a compound represented by the formula (1).

At this time, the polythiol compound and the polyisocyanate compound may be conventional ones used for the synthesis of polythiourethane. Specifically, the polythiol compound may be 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiandecane, 4-mercaptomethyl-3,6-dithia- , 8-octanedithiol, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 1,9-dimercapto-3,7-dithianone, 1,13-di Mercapto-3,7,11-trithiatridecane, glycol di (3-mercaptopropionate), 1,4-dithiane-2,5-diyl methanethiol, 2-mercaptomethyl- -Dimercapto-3-thiapentane, trimethylolpropane tri (3-mercaptopropionate, 4,8-di (mercaptomethyl) -1,11-dimercapto-3,6,9- (Mercaptoethyl) -1,12-dimercapto-3,7,10-trithiadodecane, pentaerythritol tetra (3-mercaptopropionate), pentaerythritol But are not limited to, tetra (mercaptoacetate), pentaerythritol tetrakis (2-mercaptoacetate), or mixtures thereof.

Specifically, it may be pentaerythritol tetrakis (2-mercaptoacetate), 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, or a mixture thereof .

Further, the polyisocyanate compound may be selected from the group consisting of isophorone diisocyanate, dicyclohexylmethane-4,4-diisocyanate, hexamethylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 1,6,11-undecatriisocyanate, 1,3,6-hexamethylene triisocyanate, 1 (Isocyanatoethyl) carbonate, bis (isocyanatoethyl) ether, 1,2-bis (isocyanatomethyl) cyclohexane, isocyanatomethylcyclohexane, But are not limited to, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, (Isocyanatoethyl) sulfide, bis (isocyanatoethyl) sulfide, bis (isocyanatohexyl) sulfide, bis (isocyanatohexyl) sulfide, Bis (isocyanatomethyl) sulfone, bis (isocyanatomethyl) disulfide, bis (isocyanatopropyl) disulfide, bis (isocyanatomethylthio) methane, bis Diisocyanato-2-isocyanatomethyl-3-thiapentane, bis (isocyanatoethylthio) ethane, bis (isocyanatomethylthio) 2,5-bis (isocyanatomethyl) thiophene, 2,5-bis (isocyanatomethyl) thiophene, 2,5-diisocyanatotetrahydrothiophene, Thiophene, 3,4-bis (isocyanatomethyl) tetrahydrothiophene, 2,5-diisocyanato-1,4-dithiane, 2,5-bis 1,4-dithiane, 4,5-diisocyanato-1,3-dithiolane, 4,5-bis (isocyanatomethyl) -1,3-dithiolane, 4,5-bis (isocyanatomethyl) -2-methyl-1,3-dithiolane, and the like; (Isocyanatoethyl) benzene, bis (isocyanatoethyl) benzene, bis (isocyanatoethyl) benzene, bis (isocyanatoethyl) Examples of the aromatic diisocyanate compound include aromatic diisocyanates such as phenyl ether, phenylenediisocyanate, ethylphenylenediisocyanate, isopropylphenylenediisocyanate, dimethylphenylenediisocyanate, diethylphenylenediisocyanate, diisopropylphenylenediisocyanate, trimethylbenzene triisocyanate, Toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, bibenzyl-4,4-diisocyanate, bis (isocyanato Phenyl) ethylene, 3,3-dimethoxybiphenyl-4,4-diisocyanate, hexahydrobenzene diisocyanate, hexahydrate Xylene diisocyanate, xylene diisocyanate, x-xylene diisocyanate, water-added m-xylene diisocyanate, diphenyl sulfone diisocyanate, diphenyl sulfone diisocyanate, Diisocyanate, diisocyanate, diphenylsulfide-4,4-diisocyanate, 3,3-dimethoxy-4,4-diisocyanatodibenzyl thioether, bis (4- isocyanatomethylbenzene ) Sulfide, 4,4-methoxybenzenethioethylene glycol-3,3-diisocyanate, diphenyldisulfide-4,4-diisocyanate, 2,2-dimethyldiphenyldisulfide-5,5-diisocyanate , 3,3-dimethyl diphenyl disulfide-5,5-diisocyanate, 3,3-dimethyl diphenyl disulfide-6,6-diisocyanate, 4,4-dimethyl diphenyl disulfide- Isocyanate, 3,3-dimethoxydiphenyl disulfide-4,4-diisocyanate, 4,4-dimethoxydiphenyl disulfide-3,3- Diisocyanate, and mixtures thereof.

More specifically, it may be water-added m-xylylenediisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, m-xylene diisocyanate, toluene diisocyanate, and the like.

Further, the catalyst may contain the compound represented by the above formula (1), and the detailed description thereof is as described above.

Further, the process for producing the polythiourethane-based compound comprises the steps of: (2) heating the polymerizable composition at a temperature of 5 to 20 DEG C or 5 to 15 DEG C and 0.1 to 10 torr, or 0.5 to 5 torr pressure for 0.5 to 3 hours, Deg.] C for 2 hours. Specifically, the polymerizable composition is defoamed at a relatively low temperature range of 20 占 폚 or less, 15 占 폚 or less, 5 to 20 占 폚, or 5 to 15 占 폚 prior to polymerization, thereby minimizing bubbling and improving appearance characteristics . Further, the defoaming process may be defoamed at a pressure of 0.1 to 10 torr, or 0.5 to 5 torr for 0.5 to 3 hours, or 0.5 to 2 hours. Within the above-mentioned range, there is an advantage that the bubbles in the mixture can be sufficiently removed to eliminate the apparent bubble defect that may occur during curing.

The method for producing the polythiourethane compound includes the steps of (3) stabilizing the polymerizable composition after completion of the defoaming step at a temperature of 5 to 25 DEG C, or 10 to 20 DEG C for 2 to 20 hours, or 3 to 10 hours . In the stabilization step, the viscosity can be further increased by leaving the polymerizable composition immediately after the defoaming at the temperature and for the time in the above range.

The polymerizable composition after the defoaming and stabilizing step may have a viscosity of from 10 to 150 cps, or from 20 to 140 cps at 5 to 20 캜, or at about 10 캜.

As described above, the viscosity of the polymerizable composition can be maintained at an appropriate level by performing the degassing and stabilizing step at a low temperature, and the appearance characteristics of the lens thus produced can be further improved.

Further, the polymerizable composition may satisfy the following formula (1).

 [Equation 1]

Q = (molecular weight of X x x I) / (molecular weight of compound of formula (1) x 1000 P)

Wherein Q is a general constant, 0.5 ≤ Q ≤ 3, I (change in viscosity) = I _t / I _o , 1.2 ≤ I ≤ 3, and I _o and I _t are measured at 10 ° C. after defoaming Initial viscosity and viscosity measured after 5 hours, and P is the content of the compound represented by the formula (1) when the content of the polyisocyanate compound and the polythiol compound in the polymerizable composition is 100, X and n As described in Formula 1, X is halogen, and n may be an integer of 1 to 4.

Specifically, the polymerizable composition may have a viscosity difference, that is, a viscosity change rate, of 1.2? I? 3 immediately after defoaming and after 5 hours after defoaming, and the occurrence of defects such as air bubbles, .

In addition, the manufacturing method may include stabilizing the polymerizable composition at a temperature of 5 to 25 占 폚, or 10 to 20 占 폚 for 2 to 20 hours, or 3 to 10 hours after the polymerizable composition is defoamed and polymerized. When it is within the above range, the appearance characteristic of the lens can be further improved.

The method for producing the polythiourethane compound may be prepared by (4) polymerizing the stabilized polymerizable composition.

Specifically, the polymerizable composition is degassed under reduced pressure, and then injected into a lens molding mold. Such degassing and mold injection can be performed, for example, at a temperature range of 20 to 40 캜. After injection into the mold, the polymerization is usually carried out by gradually heating from a low temperature to a high temperature. The temperature of the polymerization reaction may be, for example, 20 to 150 ° C, and specifically 25 to 120 ° C.

Further, the polythiourethane-based plastic lens produced from the mold is separated. At this time, the polythiourethane-based plastic lens can be manufactured into various shapes by changing the mold of the mold used in the production. Specifically, it may be in the form of a spectacle lens, a camera lens, or the like.

The polymerizable composition may further contain an additive such as an internal mold release agent, a heat stabilizer, an ultraviolet absorber, and a blueing agent depending on the purpose.

Examples of the internal release agent include a fluorine-based nonionic surfactant having a perfluoroalkyl group, a hydroxyalkyl group or a phosphate ester group; A silicone-based nonionic surfactant having a dimethylpolysiloxane group, a hydroxyalkyl group or a phosphate ester group; Alkyl quaternary ammonium salts such as trimethylcetylammonium salt, trimethylstearyl, dimethylethylcetylammonium salt, triethyldodecylammonium salt, trioctylmethylammonium salt, diethylcyclohexadecylammonium salt and the like; And acidic phosphate esters may be used singly or in combination of two or more.

Examples of the thermal stabilizer include a metal fatty acid salt, phosphorus, lead, and an organosilicate.

Examples of the ultraviolet absorber include benzophenone, benzotriazole, salicylate, cyanoacrylate, oxanilide, and the like.

The bluing agent has an absorption band in the wavelength range from orange to yellow in the visible light region and has a function of adjusting the color of the optical material made of the resin. Specifically, the bluing agent may include a material that exhibits blue to violet, but is not particularly limited. Examples of the bluing agent include dyes, fluorescent whitening agents, fluorescent pigments, and inorganic pigments, but they can be appropriately selected in accordance with physical properties and resin color required for the produced optical component. These bluing agents may be used alone or in combination of two or more.

The bluing agent is preferably a dye in view of the solubility in the polymerizable composition and the transparency of the resulting optical material. Specifically, the dye may be a dye having a maximum absorption wavelength of 520 to 600 nm, and more particularly, a dye having a maximum absorption wavelength of 540 to 580 nm. Further, in view of the structure of the compound, the dye is preferably an anthraquinone dye. The method of adding the bluing agent is not particularly limited and may be added to the monomer system in advance. Specifically, the method of adding the bluing agent may be a method of dissolving the monomer in a monomer, or a method of preparing a master solution containing a high concentration of a bluing agent and diluting the monomer solution or other additives using the master solution and adding You can use branching methods.

The embodiment can provide a polythiourethane-based compound and a polythiourethane-based plastic lens by the method as described above.

The plastic lens may be subjected to surface polishing, antistatic treatment, hard coat treatment, anti-reflection coat treatment, anti-reflection treatment, anti-reflection treatment, anti- A dyeing treatment, a dimming treatment, and the like.

As described above, the process for producing a polythiourethane-based compound according to the present invention is a process for producing a polythiourethane-based compound by slowly controlling the initial reactivity of a composition by performing a defoaming and stabilizing step of a polymerizable composition at a low temperature, Generation can be suppressed. Further, when the temperature is higher than the predetermined temperature, the catalytic activity is maintained smoothly, and defects such as fogging, whitening, and the like caused by unevenness in hardening can be prevented. Further, since the problems of thermal and mechanical property deterioration caused by uncured curing can be solved when the final curing process is completed, it can be usefully used for manufacturing various plastic lenses such as spectacle lenses and camera lenses.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

[ Example ]

Manufacturing example  One.

219.2 parts by weight of water-added m-xylylene diisocyanate, 124.3 parts by weight of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 2 parts by weight of pentaerythritol tetrakis -Mercaptoacetate) were uniformly mixed to prepare a composition 1.

Manufacturing example  2.

201.4 parts by weight of m-xylylene diisocyanate, and 196.1 parts by weight of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiandecane were uniformly mixed to prepare Composition 2.

Manufacturing example  3.

204.2 parts by weight of m-xylylene diisocyanate, and 188.0 parts by weight of 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol were uniformly mixed to prepare Composition 3.

Example  One

Polymerizable  Composition manufacturing

To 100 parts by weight of the composition 1 prepared in Preparation Example 1 were added 1.0 part by weight of 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole as an ultraviolet stabilizer, Zelec® UN 0.2 part by weight of a release agent, Stepan) and 0.03 part by weight of dimethyl tin dichloride (DMTDC) as a catalyst were mixed. The mixture was degassed at 10 < 0 > C and 2 torr for 1 hour and filtered through a 3 mu m Teflon filter to produce a polymerizable composition.

Manufacture of plastic lenses

The polymerizable composition was injected into a glass mold template assembled by tape. The mold was allowed to stand at 10 DEG C for 5 hours, then heated from 10 DEG C to 120 DEG C at a rate of 5 DEG C / min and polymerized at 120 DEG C for 18 hours. Then, the cured resin in the glass mold mold was further cured at 130 캜 for 4 hours, and then the molded body (plastic lens) was released from the glass mold mold.

 The compositions 1 to 3 and the type and content of the catalysts were varied as shown in Table 1 below. The mixture was degassed at 10 < 0 > C and 2 torr for 1 hour and filtered through a 3 mu m Teflon filter to produce a polymerizable composition.

Example  2 to 6 and Comparative Example  1 to 3

Polymerizable compositions and / or plastic lenses were prepared in the same manner as in Example 1, except that the compositions 1 to 3 and the type and / or content of the catalyst were changed as shown in Table 1 below.

[ Test Example ]

(1) Viscosity

The initial viscosity I _o of the polymerizable composition immediately after the degassing and the viscosity I _t of the polymer after 5 hours after the degassing were measured using a non-contact viscometer (EMS-1000, manufactured by Kyoto Electronics Co., Ltd.) _t / I _o was calculated.

(2) McGill

When the plastic lens was observed with the naked eye, when a non-uniform phenomenon such as a wave pattern was observed, it was indicated as?, And when the appearance was clear, it was indicated as?.

(3) Cloudiness

When the plastic lens was observed with the naked eye, the part or whole was not transparent and an opaque part was seen.

(4) Bubbles

The lens was observed with a microscope at a magnification of 100 times with respect to the plastic lens. When the bubbles were 0 in the inside, S, 1 to 10, A to 11 to 30, and C to 31 were evaluated.

(5) crack

A crack was observed in the inside of the plastic lens.

(6) Reactivity

The above plastic lens was analyzed by FT-IR of ATR type. When it was confirmed that the characteristic peak of -NCO at 2260 cm ^-1 completely disappeared, it was indicated with?, And when it did not disappear, it was indicated by?.

DMTDC: dimethyl tin dichloride (molecular weight 219.7)

DBTDC: Dibutyl tin dichloride (molecular weight 303.8)

As shown in Table 1, it was confirmed that the compositions of Examples 1 to 6 were adjusted to an appropriate level within a range of 1.2? I? 3, as compared with Comparative Examples 1 to 3, As a result, it was found that the appearance of the plastic lens was excellent and the response was high. Thus, it is expected that the use of the composition of the embodiment can improve the processability (workability) in the production of plastic lenses and can be usefully used because a plastic lens having improved appearance characteristics can be obtained.

Claims (10)

The polymerizable composition comprising a polythiol compound, a polyisocyanate compound, and a halogen tin catalyst is defoamed at a temperature of 5 to 15 DEG C and a pressure of 0.1 to 10 torr for 0.5 to 3 hours and then stabilized at the same temperature condition for 5 to 30 hours ≪ / RTI > based on the weight of the polythiourethane compound. The method according to claim 1,
Wherein the catalyst is a compound represented by the following formula (1): < EMI ID =
[Chemical Formula 1]

In this formula,
X is halogen,
Y is optionally substituted C _1-10 alkyl, C _1-30 alkoxy, C _4-30 cycloalkyl, C _4-30 heteroaryl, C _6-30 aryl, C _1-30 alkyl-substituted C _{6- 30} aryl or C _6-30 aryloxy,
n and m are each independently an integer of 1 to 4, n + m = 4,
when n is 2 or more, X is the same or different from each other,
When m is 2 or more, Y is the same or different from each other. 3. The method of claim 2,
Wherein X is Cl,
Wherein Y is substituted or unsubstituted C _1-10 alkyl, phenyl or C _1-30 alkyl-substituted phenyl. 3. The method of claim 2,
Wherein X is Cl,
And Y is substituted or unsubstituted C _1-10 alkyl. 3. The method of claim 2,
Wherein the compound of Formula 1 is dimethyltin chloride or dibutyltin chloride. The method according to claim 1,
Wherein the polymerizable composition after the defoaming and stabilization step has a viscosity of 10 to 150 cps at 10 占 폚. 3. The method of claim 2,
Wherein the polymerizable composition satisfies the following formula (1): < EMI ID =
[Equation 1]
Q = (molecular weight of X x x I) / (molecular weight of compound of formula (1) x 1000 P)
In this formula,
Q is a general constant, 0.5? Q? 3,
I (change in viscosity) = I _t / I _o , 1.2? I? 3,
I _o and I _t are initial viscosities measured at 10 ° C after defoaming and measured after 5 hours,
P is the content of the compound represented by the formula (1) when the content of the polyisocyanate compound and the polythiol compound in the polymerizable composition is 100,
X and n are as defined in claim 2. The method according to claim 1,
Wherein the catalyst is used in an amount of 0.001 to 0.1 part by weight based on 100 parts by weight of the polymerizable composition. A polythiourethane-based compound obtained by the process of any one of claims 1 to 8. A plastic lens molded from the polythiourethane compound of claim 9.