JP2005213315A - Production method for macromolecular polymer porous film and macromolecular polymer porous film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for a macromolecular polymer porous film, which excels in forming a thin film and can easily control stable porous characteristics. <P>SOLUTION: The macromolecular polymer porous film is obtained by the followings. After a solution composed of a macromolecular polymer insoluble in water, a solvent (solvent 1) which is a good solvent for the macromolecular polymer and compatible with water, and a solvent (solvent 2) which is a poor solvent for the macromolecule polymer and compatible with water, in the state of being mutually dissolved, is made to a film shape on a supporting body, ≥0.5 wt.% water, based on the amount of the solvents (the solvents 1 and 2), is absorbed in the solution, precipitating the macromolecule polymer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polymer porous membrane that can be suitably used for filters, separation membranes, battery separators, printed boards, and the like, and a polymer polymer porous membrane.

  Conventionally, as a method for producing a polymer porous membrane by a solution casting method, for example, in Patent Document 1, after casting a polyamic acid solution, a porous film is laminated and immersed in a poor solvent. A manufacturing method is disclosed. Patent Document 2 discloses a manufacturing method characterized by laminating a liquid protective layer after casting a polymer and immersing it in a poor solvent.

  However, in these above methods, it is necessary to laminate a protective layer again after casting the polymer solution, which complicates the process. Further, since the protective layer is provided on the polymer solution having fluidity, stable lamination is difficult, and it is difficult to control the characteristics of the porous film.

  Patent Document 3 discloses a production method characterized in that a poor solvent is added to a polymer solution to form a gel polymer solution, and then a film is formed. In this method, the gelled solution is uniformly formed. It is difficult to cast and it is difficult to produce a thin porous membrane.

Further, Patent Document 4 discloses a manufacturing method characterized in that after a metal oxide fine particle dispersed in a polymer solution is cast to obtain a film, the metal oxide fine particle is dissolved and removed. However, with this method, it is not possible to obtain a pore having a size smaller than that of the metal oxide fine particles, and it is difficult to dissolve and remove the metal oxide fine particles with respect to the film thickness. There was a problem that it remained in the film.
JP-A-11-310658 JP 2003-165128 A JP 2002-327084 A JP 2001-98106 A

  The present invention solves the above-described conventional problems, and provides a method for producing a polymer porous membrane that is excellent in thinning and that can easily control stable porous properties, and a polymer porous membrane For the purpose.

  In order to achieve the above object, the present invention provides a polymer that exhibits water insolubility, a solvent (solvent 1) that is a good solvent for the polymer and is compatible with water, and the polymer. A solution compatible with each other, which is a poor solvent for the polymer and a solvent compatible with water (solvent 2), is formed into a film shape on the support, and is then added to the solvent (solvent 1 and solvent 2). It is characterized by a method for producing a high molecular weight polymer porous membrane in which 0.5% by weight or more of water is absorbed into the solution and the high molecular weight polymer is precipitated.

  According to the present invention, as will be described below, a porous membrane having a desired porosity and a Gurley value and having a high strength and capable of being thinned is obtained. A filter, a separation membrane, and a battery separator It can be suitably used for printed circuit boards.

  As used in the present invention, a polymer that exhibits water insolubility (hereinafter sometimes simply referred to as a polymer) refers to a polymer that generally exhibits water insolubility, for example, at −30 to 80 ° C. It is preferred that the solubility in water is less than 1% by weight. Specifically, for example, polyethylene, polypropylene, polyester, polysulfone, polycarbonate, polyamide, polyimide, polyamideimide, aromatic polyamide, fluorine resin, and the like can be used. These polymers may be used alone or in a mixture of several kinds. Aromatic polyamide is preferred because of its high strength and possible thinning.

  In the present invention, a solvent that is a good solvent for a polymer and that is compatible with water (hereinafter sometimes referred to as solvent 1) refers to a solvent that dissolves the polymer used and is compatible with water. These organic solvents can be used. Here, as the solvent, for example, a solvent in which the solubility of the polymer to be used is 1% by weight or more at −30 to 80 ° C. is preferable. Specifically, aprotic organic polar solvents such as N-methylpyrrolidone, dimethylacetamide, and dimethylformamide are preferable from the viewpoint of solubility and ease of solvent extraction.

  In the present invention, a solvent that is a poor solvent for a polymer and that is compatible with water (hereinafter sometimes referred to as solvent 2) refers to a solvent that has a low polymer solubility and is compatible with water. Various organic solvents can be used. Here, as the solvent, for example, a solvent in which the solubility of the polymer to be used is less than 1% by weight at −30 to 80 ° C. is preferable. Specifically, a water-soluble ether solvent such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, trioxane or the like, or a water-soluble alcohol solvent such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, diethylene glycol or the like should be used. Can do. Moreover, it can use preferably also about the polymer of ethylene glycol or diethylene glycol.

  In the present invention, a high molecular weight polymer (polymer) showing water insolubility, a solvent that is a good solvent for the polymer and compatible with water, a poor solvent for the polymer and a compatibility with water The solution composed of the solvent shown is preferably in a mutually compatible / dissolved state, and is preferably a solution that is completely and completely compatible without any suspended matter or precipitate in the solution. For example, if the solution is gelled and loses fluidity, or suspended matter, precipitates, etc. are generated, it is difficult to make a thin film, and unevenness in the porous properties is likely to occur.

  In the present invention, after the above solution is formed into a film shape on the support, 0.5% by weight or more of water is absorbed with respect to the solvent (total amount of the solvent 1 and the solvent 2) to precipitate the polymer. Combined porous membrane. In particular, by using a solution that has good fluidity and is completely and completely compatible, a uniformly thin membrane can be cast on the support, and further by absorbing water, the solubility of the solvent in the polymer can be increased. The porous film can be rapidly formed. If the amount of water absorbed is less than 0.5% by weight, the polymer may not be precipitated, or even if it is precipitated, it may be necessary to wait for a long time after absorbing the water. On the other hand, when the amount of water absorption exceeds 30% by weight, the polymer concentration may be lowered by water, and the strength of the porous membrane may be lowered and become brittle. In the above process, it is preferable that the mixture of water and the solvent does not form droplets on the surface of the porous membrane. Depending on the composition of the solution, if a large amount of moisture is absorbed under high humidity, droplets may be formed on the surface, which may cause spots on the solution composition, resulting in spots on the properties of the porous film. is there.

  Moreover, it is preferable that the solvent (solvent 2) which is a poor solvent with respect to the above-mentioned polymer and is compatible with water is a water-soluble alcohol having 2 to 25 carbon atoms. By changing the number of carbons, the size and porosity of the pores can be finely adjusted, and since the volatility is low, the solution composition is stable and can be easily mixed and extracted. Is more preferable.

Moreover, as aromatic polyamide which can be preferably used in this invention, what has a repeating unit represented by following formula (1) and / or Formula (2) is suitable.
Formula (1):

Formula (2):

Here, as the group of Ar ₁ , Ar ₂ , Ar ₃ , for example,

And the groups of X and Y are
_{-O -, - CH 2 -,} - CO -, - CO 2 -, - S -, - SO 2 -, - C (CH 3) 2 - may be selected from such.

Furthermore, some of the hydrogen atoms on these aromatic rings are halogen groups such as fluorine, bromine and chlorine (especially chlorine), nitro groups, alkyl groups such as methyl, ethyl and propyl (especially methyl groups), methoxy and ethoxy. Those substituted with a substituent such as an alkoxy group such as propoxy are preferred because the moisture absorption is lowered and the dimensional change due to humidity change is reduced. In addition, hydrogen in the amide bond constituting the polymer may be substituted with another substituent. In the aromatic polyamide used in the present invention, the above aromatic ring having para orientation is preferably 80 mol% or more, more preferably 90 mol% or more of the total aromatic ring. Para-orientation here means a state in which the divalent bonds constituting the main chain on the aromatic nucleus are coaxial or parallel to each other. When this para-orientation is less than 80 mol%, the high molecular weight polymer porous membrane may have insufficient rigidity and heat resistance. Furthermore, when the aromatic polyamide contains 60 mol% or more of the repeating unit represented by the formula (3), it is preferable because stretchability and porous properties are particularly excellent.
Formula (3):

  The polymer polymer porous membrane obtained by the method of the present invention preferably has a Gurley value of 0.5 to 1,000 sec / 100 cc. When the Gurley value of the porous membrane is within this range, it can be suitably used for filters, separation membranes, battery separators, printed boards and the like.

  Next, the method for producing a porous membrane of the present invention will be described below using a case where an aromatic polyamide is used as a polymer as a representative example.

  When an aromatic polyamide is obtained from, for example, acid chloride and diamine, solution polymerization in an aprotic organic polar solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, interfacial polymerization using an aqueous medium, etc. Synthesize with When acid chloride and diamine are used as monomers, hydrogen chloride is by-produced in the polymer solution. To neutralize this, inorganic neutralizers such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene Organic neutralizers such as oxide, propylene oxide, ammonia, triethylamine, triethanolamine, and diethanolamine are preferably used. Moreover, when obtaining aromatic polyamide from reaction of isocyanate and carboxylic acid, it can carry out in presence of a catalyst in an aprotic organic polar solvent.

In order to obtain the porous membrane of the present invention, the intrinsic viscosity η _{inh of the} polymer (value measured at 30 ° C. in a 100 ml solution of 0.5 g of polymer in 98 wt% sulfuric acid) is 0.5 (dl / g) The above is preferable because the handling property when a porous film is formed is improved.

  In some cases, an inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, lithium nitrate, or the like is added to the stock solution as a dissolution aid. In addition, as a film-forming stock solution, water-soluble alcohols may be used by mixing with a neutralized polymer solution, or once the polymer is isolated, it is redissolved in an aprotic organic polar solvent and dissolved in water. A mixture of alcoholic alcohols may be used. The polymer concentration in the film-forming stock solution is preferably about 2 to 30% by weight. Since a thin and stable porous film having a stable porous property can be obtained efficiently, it is more preferably 8 to 25% by weight, still more preferably 12 to 20% by weight. Moreover, since a polymer precipitates rapidly when water is absorbed, 2 to 40 weight% of water-soluble alcohols mixed are preferable. More preferably, it is 5-30 weight%, More preferably, it is 10-25 weight%.

  The film-forming stock solution prepared as described above is made into a porous film by a so-called solution film-forming method. The solution casting method includes dry and wet methods, wet methods, and deposition methods, and any method can be used. However, since the inner structure of the porous membrane is uniform, the deposition method can be used. More preferred.

  When a polymer porous membrane is produced by the precipitation method, the polymer is obtained by absorbing the water after making the membrane shape by casting the solution on a support such as a glass plate, a drum or an endless belt. Precipitate. At this time, the method of absorbing water may be any of the method of adhering mist-like water, the method of introducing into water, or the method of introducing into humidity-controlled air. A method of introducing into the conditioned air that can be controlled is preferably used.

  When the solution in the form of a film is introduced into the conditioned air, it is preferable to deposit the polymer in the air conditioned to 5 to 100% relative humidity. The temperature at this time is preferably −30 ° C. to 80 ° C. Although it cannot be generally limited by various conditions such as humidity, temperature, solution composition, and introduction time, an example of the characteristics of the porous film obtained by the conditions is as follows. A porous membrane having pores can be obtained, and under low temperature and low humidity, a porous membrane in which fibrous polymers with small pore diameters are overlapped in a network or nonwoven fabric is obtained. In consideration of the above, it is possible to obtain a porous film having desired characteristics by appropriately changing the conditions.

  The solution (polymer film) after the polymer deposition is introduced into a wet bath in the next wet process, and the solvent is removed. At this time, it may be peeled off from the support and introduced into the wet bath, or may be peeled off after being introduced into the wet bath together with the support. The bath composition is not particularly limited as long as the solubility in the polymer is low, but it is preferable to use water or an organic solvent / water mixed system in view of economy and ease of handling. Further, the wet bath may contain an inorganic salt.

  At this time, in order to reduce impurities in the porous film, the bath composition is preferably organic medium / water = 70/30 to 20/80, and the bath temperature is 40 ° C. or higher. Furthermore, it is effective to finally pass through a water bath at 40 ° C. or higher.

  The porous film that has been desolvated is subjected to heat treatment. The temperature at this time is preferably higher because the dimensional stability at high temperature is improved, but it is necessary to be lower than the thermal decomposition temperature of the polymer used. In the aromatic polyamide, thermal decomposition is performed at 350 to 400 ° C., and thus heat treatment is performed at a temperature lower than that. Preferably it is 250-320 degreeC.

  The porous film obtained by the method of the present invention preferably has a Gurley value of 0.5 to 1,000 sec / 100 cc. According to the production method of the present invention, even if the Gurley value is small, it is possible to maintain the mechanical strength, and even if the Gurley value is large, it is possible to provide a suitable porosity and pore diameter. . When the Gurley value is smaller than 0.5 sec / 100 cc, the strength is remarkably reduced. When the Gurley value is larger than 1,000 sec / 100 cc, it is difficult to use the filter practically for a filter or a separator.

  The polymeric polymer porous membrane of the present invention can be suitably used for filters, separation membranes, battery separators, printed boards and the like.

[Methods for measuring physical properties and methods for evaluating effects]
The measurement method of physical properties and the evaluation method of effects in the present invention were performed according to the following methods.

(1) Gurley value It measured according to the method prescribed | regulated to JIS-P8117. The porous membrane of the sample is clamped in a circular hole having a diameter of 28.6 cm and an area of 645 mm ² . By the inner cylinder (inner cylinder weight 567 g), the air in the cylinder is allowed to pass from the test hole to the outside of the cylinder. The time required for 100 cc of air to pass through was measured and used as the Gurley value. As a measuring device, a B-type Garredenometer (manufactured by Yasuda Seiki Seisakusho) was used.

(2) Porosity The porous membrane was cut into a 100 mm square, and weight W (g) and thickness Z (mm) were measured. Using the specific gravity H (g / mm ² ) of the polymer used, the porosity was determined from the following equation.

Porosity (%) = 100-100 × ((W / H) / (100 ² × Z))
(3) Thickness Using an electronic micrometer manufactured by Kansai Anritsu Electronics Co., Ltd. (detector model number: K107C, stylus radius 1.5 mm, stylus load 1.5 g), an average measured at five locations at 100 mm intervals in the length direction. The value was taken as thickness.

(4) Breaking strength Measurement was performed according to the method defined in JIS-K7127. Measurement was performed at 25 ° C. and a relative humidity of 65% using Robot Tensilon RTA (Orientec). The test piece has a width of 10 mm, a length of 100 mm, and a pulling speed of 300 mm / min.

(5) Moisture absorption rate After coating in a film form on a glass plate with a known weight, the weight was accurately weighed to the nearest 0.01 g in a nitrogen atmosphere without moisture absorption, and the weight excluding the weight of the glass plate (W0 ) From this, the total weight (Y0) of the solvent and the poor solvent is derived according to the composition of the solution. After the formation of the porous film, the same measurement and calculation are performed again, and the total weight (Y1) of the solvent, the poor solvent, and the absorbed water is derived according to the composition of the solution, and the moisture absorption rate is obtained by the following equation. .

Moisture absorption rate (%) = 100 × ((Y1-Y0) / Y1)
(6) Battery characteristics A. Preparation of Electrolytic Solution After dissolving LiC ₄ F ₉ SO ₃ in trimethyl phosphate, propylene carbonate was added and mixed, and LiC ₄ F ₉ was added to a mixed solvent having a volume ratio of propylene carbonate to trimethyl phosphate of 1: 2. An organic electrolytic solution in which SO ₃ was dissolved at 0.6 mol / liter was prepared. In order to investigate the flash point of the organic electrolyte solution thus obtained, the electrolyte solution was heated to a predetermined temperature, and a fire was brought close to the liquid surface to investigate whether it would ignite. In any test at 100 ° C., 150 ° C., and 200 ° C., no ignition was performed, and it was found that the flash point of the electrolytic solution was 200 ° C. or more.

B. Preparation of Battery A slurry in which graphite and polyvinylidene fluoride are added to lithium cobalt oxide (LiCoO ₂ ) and dispersed in a solvent is uniformly applied to both sides of the aluminum foil of a positive electrode current collector having a thickness of 10 μm and dried. The belt-shaped positive electrode was produced by compression molding. The thickness of the positive electrode was 40 μm.

Coke and polyvinylidene fluoride as an adhesive were mixed to form a negative electrode mixture, which was dispersed in a solvent to form a slurry. This negative electrode mixture slurry was uniformly applied to both surfaces of a 10 μm-thick strip-shaped copper foil as a negative electrode current collector, dried, and compression molded to prepare a strip-shaped negative electrode precursor. As a treatment liquid for the negative electrode precursor, LiC ₄ F ₉ SO ₃ was dissolved in trimethyl phosphate, and then ethylene carbonate was added and mixed to prepare a treatment liquid. The lead body was squeezed with Li foil through a separator impregnated with a treatment liquid on both sides of the negative electrode precursor, placed in a holder, and discharged and charged using the negative electrode precursor as the positive electrode and the Li electrode as the negative electrode. Then, it decomposed | disassembled, the negative electrode precursor was wash | cleaned with dimethyl carbonate, and it dried and produced the negative electrode. The thickness of the negative electrode was 50 μm.

  Next, the belt-like positive electrode is overlapped with the sheet-like negative electrode through the separator film of each example and wound into a spiral electrode body, and then a bottomed cylindrical battery having an inner diameter of 13 mm. After filling the case and welding the positive and negative electrode lead bodies, the organic electrolyte was poured into the battery case. The opening of the battery case was sealed and the battery was precharged to produce a cylindrical organic electrolyte secondary battery.

C. Battery capacity Each of the produced secondary batteries was charged at 35 mA and discharged at 4.1 V and discharged at 2.7 V, and the discharge capacities at the first and tenth cycles were examined. Based on the discharge capacity at the first cycle, the discharge capacity at the 10th time is
A: 95% or more B: 90% or more and less than 95% C: Evaluation was made with a rank of less than 90%, and rank B or more was regarded as acceptable.

  Hereinafter, the present invention will be described more specifically based on examples, but it goes without saying that the present invention is not limited thereto.

(Example 1)
2-chloroparaphenylenediamine corresponding to 80 mol% and 4,4′-diaminodiphenyl ether corresponding to 20 mol% are dissolved in dehydrated N-methyl-2-pyrrolidone, which corresponds to 98.5 mol%. 2-chloro terephthalic acid chloride was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to obtain an aromatic polyamide solution having a polymer concentration of 11% by weight. This solution was reprecipitated with water to remove the polymer.

  The polymer was weighed to 15% by weight, 75% by weight of N-methyl-2-pyrrolidone, and 10% by weight of diethylene glycol, dissolved in N-methyl-2-pyrrolidone, and then added with diethylene glycol. A polymer solution was obtained.

  This polymer solution is formed into a film of about 50 μm on a glass plate using a bar coater, and left in an oven adjusted to 20 ° C. and a relative humidity of 80% for 1 hour to perform precipitation, did. The moisture absorption rate at this time was 15%. The porous film was peeled from the glass plate, and the solvent and impurities were extracted for 1 hour in a 50 ° C. water bath. Thereafter, it was fixed to an aluminum frame, air-dried for 3 hours, and then heat-treated at 320 ° C. for 1 minute.

  The thickness of the obtained porous film was 41.7 μm, the breaking strength was 140 MPa, the porosity was 25%, and the Gurley value was 302 sec / 100 cc.

  Using the obtained porous membrane, a battery was prepared and the decrease in discharge capacity was measured. As a result, 98% was maintained.

(Examples 2 to 5)
Using the polymer obtained in the same manner as in Example 1, a solution having the composition shown in Table 1 was obtained. These polymer solutions are formed into a film shape of about 50 μm on a glass plate using a bar coater, and left in an oven adjusted to 20 ° C. and a relative humidity of 80% for 1 hour to perform precipitation, did. The moisture absorption rate at this time is also shown in Table 1. The porous film was peeled from the glass plate, and the solvent and impurities were extracted for 1 hour in a 50 ° C. water bath. Thereafter, it was fixed to an aluminum frame, air-dried for 3 hours, and then heat treated at 320 ° C. for 1 minute to obtain a porous film. The physical properties of the obtained porous membrane are shown in Table 1.

(Example 6)
A porous membrane was obtained in the same manner as in Example except that it was allowed to stand for 20 minutes in an oven adjusted to 20 ° C. and relative humidity 10%. The physical properties of the obtained porous membrane are shown in Table 1.

(Example 7)
A porous membrane was obtained in the same manner as in Example except that it was allowed to stand for 3 hours in an oven adjusted to 20 ° C. and relative humidity 80%. The physical properties of the obtained porous membrane are shown in Table 1.

(Comparative Example 1)
Using the polymer obtained in the same manner as in Example 1, the polymer was mixed at 15% by weight and N-methyl-2-pyrrolidone 85% by weight to obtain a uniformly and completely compatible polymer solution.

  This polymer solution is formed into a film of about 50 μm on a glass plate using a bar coater, and left in an oven adjusted to 20 ° C. and a relative humidity of 80% for 1 hour to perform precipitation, did. The moisture absorption rate at this time was 18%. The porous film was peeled from the glass plate, and the solvent and impurities were extracted for 1 hour in a 50 ° C. water bath. Thereafter, it was fixed to an aluminum frame, air-dried for 3 hours, and then heat-treated at 320 ° C. for 1 minute.

  The obtained porous membrane had a thickness of 32.4 μm, a breaking strength of 180 MPa, a porosity of 25%, no aeration, and a Gurley value and battery characteristics were not measurable.

(Comparative Example 2)
Using the polymer obtained in the same manner as in Example 1, this polymer was weighed to 15% by weight, N-methyl-2-pyrrolidone 75% by weight, and diethylene glycol 10% by weight. -After dissolving in pyrrolidone, diethylene glycol was added to obtain a uniformly and completely compatible polymer solution.

  This polymer solution was formed into a film of about 50 μm on a glass plate using a bar coater and allowed to stand in an oven adjusted at 20 ° C. in a nitrogen atmosphere for 1 hour, but no polymer was deposited.

(Comparative Example 3)
Using the polymer obtained in the same manner as in Example 1, this polymer was weighed out to 2% by weight, N-methyl-2-pyrrolidone 88% by weight, and diethylene glycol 10% by weight. -After dissolving in pyrrolidone, diethylene glycol was added to obtain a uniformly and completely compatible polymer solution.

  This polymer solution is formed into a film of about 50 μm on a glass plate using a bar coater, and left in an oven adjusted to 20 ° C. and a relative humidity of 80% for 2 hours to perform precipitation, did. The water absorption rate at this time was 32%. The porous film was peeled from the glass plate, and the solvent and impurities were extracted for 1 hour in a 50 ° C. water bath. Thereafter, it was fixed to an aluminum frame, air-dried for 3 hours, and then heat-treated at 320 ° C. for 1 minute.

  The thickness of the obtained porous film was 53.3 μm, the breaking strength was 25 MPa, the porosity was 70%, and the Gurley value was 0.4 sec / 100 cc.

  Using the obtained porous membrane, a battery was produced and the reduction in discharge capacity was measured. As a result, it was found to be 87%.

  The present invention relates to a method for producing a high molecular weight polymer porous membrane that can be suitably used for a filter, a separation membrane, a battery separator, a printed circuit board, and the like, but its application range is not limited thereto.

Claims (5)

A water-insoluble polymer, a solvent that is a good solvent for the polymer and water-compatible (solvent 1), a solvent that is poor for the polymer, and water A compatible solution composed of a compatible solvent (solvent 2) is formed into a film shape on a support, and then 0.5% by weight or more of water is added to the solution (solvent 1 and solvent 2). A method for producing a high molecular weight polymer porous membrane, wherein the high molecular weight polymer is deposited by absorption into a polymer. The method for producing a porous polymer porous membrane according to claim 1, wherein 0.5 to 30% by weight of water is absorbed into the solution. The method for producing a porous polymer porous membrane according to claim 1 or 2, wherein the solvent 2 is a water-soluble alcohol having 2 to 25 carbon atoms. The method for producing a porous polymer polymer membrane according to any one of claims 1 to 3, wherein the water-insoluble polymer is an aromatic polyamide. A high molecular weight polymer porous membrane having a Gurley value of 0.5 to 1,000 sec / 100 cc produced by the production method according to claim 1.