JP7581780B2 - Resin composition, paint and plastic molded product coated with said paint - Google Patents

Description

The present invention relates to a resin composition, a paint, and a plastic molded product coated with the paint.

Polyolefin-modified acrylic resins obtained by reacting unsaturated monomers in the presence of polyolefins have been proposed, and the resulting cured coating films are known to have excellent adhesion to substrates, water resistance, and other properties (see, for example, Patent Document 1). On the other hand, in recent years, there has been a demand for reducing the burden on the environment, and there is a demand for thin film-forming methods that can be performed at low temperatures.

However, although the coating film obtained from this polyolefin-modified acrylic resin has excellent water resistance, there is a problem that the adhesion performance is insufficient depending on the film-forming conditions.

JP 2015-13944 A

The problem that the present invention aims to solve is to provide a resin composition, a paint, and a plastic molded article coated with the paint, which are excellent in storage stability, have high adhesion to plastic substrates, and can produce a coating film with excellent appearance.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that a resin composition containing a specific ratio of polyolefin-modified acrylic resin and a terpene solvent can provide a coating film that has excellent storage stability, high adhesion to plastic substrates, and excellent appearance, and thus completed the invention.

That is, the present invention relates to a resin composition containing a polyolefin-modified acrylic resin and a terpene solvent, characterized in that the content of the terpene solvent is 50 to 500 mass % of the polyolefin-modified acrylic resin, a paint, and a plastic molded product coated with the paint.

The resin composition of the present invention has high adhesion to plastic substrates and can produce coating films with excellent appearance, making it useful as a coating material, and the coating material can be applied to various plastic molded products. Therefore, the resin composition of the present invention can be suitably used as a coating material for coating various articles such as the housings of electronic devices such as mobile phones, smartphones, tablet terminals, personal computers, digital cameras, and game consoles; the housings of home appliances such as televisions, refrigerators, washing machines, and air conditioners; the interior materials of various vehicles such as automobiles and railway cars; and toys.

The resin composition of the present invention is a resin composition containing a polyolefin-modified acrylic resin and a terpene solvent, and the content of the terpene solvent is 50 to 500 mass % of the polyolefin-modified acrylic resin.

The polyolefin-modified acrylic resin may be a mixture of polyolefin resin (A) and acrylic resin (B), or may be a combination of polyolefin resin (A) and acrylic resin (B). However, since storage stability is further improved, it is preferable to use a combination of polyolefin resin (A) and acrylic resin (B).

A preferred method for obtaining a polyolefin-modified acrylic resin is to radically polymerize an unsaturated monomer mixture (b), which is a raw material for the acrylic resin (B), in the presence of a polyolefin resin (A).

As the polyolefin resin (A), chlorinated polyolefin resin and maleic acid modified polyolefin resin are preferred because they have excellent storage stability and adhesion of the resulting coating film. The polyolefin resin (A) can be used alone or in combination of two or more kinds.

The chlorinated polyolefin resin is a chlorinated polyolefin resin, and examples of the polyolefin resin include polypropylene, high density polyethylene, ultra-high molecular weight polyethylene, linear low density polyethylene, low density polyethylene, very low density polyethylene, ultra-low density polyethylene, polymethylpentene, ethylene-propylene copolymer, propylene-1-butene random copolymer, propylene-ethylene-1-butene random copolymer, copolymer of propylene and α-olefin having 5 to 12 carbon atoms, propylene-non-conjugated diene copolymer, ethylene-non-conjugated diene copolymer, ethylene-propylene-non-conjugated diene copolymer, polybutene, ethylene-vinyl acetate copolymer, ethylene-vinyltrimethoxysilane copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, styrene-butadiene block copolymer, and hydrogenated products thereof. The chlorinated polyolefin resin may be partially modified with maleic acid.

The chlorine content of the chlorinated polyolefin resin is preferably 15 to 40% by mass, as this further improves compatibility and adhesion.

The chlorinated polyolefin resins can be used alone or in combination of two or more types, but polymers containing polypropylene are preferred because they have improved storage stability.

The maleic acid modified polyolefin resin is a polyolefin resin modified with maleic acid, and the polyolefin resin may be any of the polyolefin resins exemplified above as being usable for the chlorinated polyolefin resin.

The maleic acid modified polyolefin resins can be used alone or in combination of two or more types, but polymers containing polypropylene are preferred because they provide improved storage stability.

The weight average molecular weight of the polyolefin resin (A) is preferably 20,000 to 250,000.

Next, the unsaturated monomer mixture (b) will be described. Since this unsaturated monomer mixture (b) can also be used in two-component curing, it is preferable that it contains an unsaturated monomer (b1) having a hydroxyl group, and from the viewpoint of pot life during two-component curing, it is more preferable that it further contains an unsaturated monomer (b2) having a carboxyl group.

Examples of the unsaturated monomer (b1) having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-n-butyl (meth)acrylate, 3-hydroxy-n-butyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, glycerin mono(meth)acrylate, polyoxyethylene mono(meth)acrylate, polyoxypropylene mono(meth)acrylate, polyoxybutylene mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, and polycaprolactone-modified hydroxyethyl mono(meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate is preferred because of its excellent curability with polyisocyanate. These unsaturated monomers (b1) can be used alone or in combination of two or more.

In the present invention, "(meth)acrylic acid" refers to either or both of methacrylic acid and acrylic acid, "(meth)acrylate" refers to either or both of methacrylate and acrylate, and "(meth)acryloyl group" refers to either or both of methacryloyl group and acryloyl group.

Examples of the unsaturated monomer (b2) having a carboxyl group include unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, β-carboxyethyl (meth)acrylate, ω-carboxy-polycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl succinate, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or half esters of these unsaturated dicarboxylic acids. Among these, (meth)acrylic acid is preferred. These unsaturated monomers (b2) can be used alone or in combination of two or more.

Examples of the unsaturated monomer (b3) other than the unsaturated monomer (b1) and the unsaturated monomer (b2) that can be contained in the unsaturated monomer mixture (b) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and tridecyl (meth)acrylate. acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, benzyl (meth)acrylate; acrylamide, N,N-dimethyl (meth)acrylamide, (meth)acrylonitrile, 3-(meth)acryloyloxypropyltrimethoxysilane, N,N-dimethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl acid phosphate, glycidyl (meth)acrylate, vinyl acetate, styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene, diacrylate compounds such as ethylene glycol diacrylate, etc. Among these, (meth)acrylate compounds are preferred, and (meth)acrylates having an alkyl group having 1 to 15 carbon atoms are more preferred. These unsaturated monomers (b3) can be used alone or in combination of two or more.

The mass ratio of the unsaturated monomer (b1) in the unsaturated monomer mixture (b) is preferably 1 to 20 mass%, more preferably 2 to 10 mass%, since this improves the balance between appearance and adhesion.

The mass ratio of the unsaturated monomer (b2) in the unsaturated monomer mixture (b) is preferably 0.1 to 10 mass%, more preferably 0.3 to 5 mass%, since this improves the balance between appearance and adhesion.

The mass ratio of methyl methacrylate in the unsaturated monomer mixture (b) is preferably 10 to 90 mass%, more preferably 25 to 60 mass%, since this provides a better balance between appearance and adhesion.

The mass ratio of the pre-unsaturated monomer (b4) in the unsaturated monomer mixture (b) is preferably 10 to 95 mass%, more preferably 50 to 90 mass%, since this provides a better balance between appearance and adhesion.

The radical polymerization method for obtaining the polyolefin-modified acrylic resin is a method in which each monomer, which is the raw material, is polymerized in the presence of a polymerization initiator. Examples of solvents that can be used in this process include aromatic hydrocarbon compounds such as toluene and xylene; alicyclic hydrocarbon compounds such as cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester compounds such as ethyl acetate, n-butyl acetate, isobutyl acetate, and propylene glycol monomethyl ether acetate; alcohol compounds such as n-butanol, isopropyl alcohol, and cyclohexanol; glycol compounds such as ethylene glycol monobutyl ether and propylene glycol monomethyl ether; and aliphatic hydrocarbon compounds such as heptane, hexane, octane, and mineral turpentine.

Examples of the polymerization initiator include ketone peroxide compounds such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, and 2,2-bis(4,4-ditert-butylperoxycyclohexyl) peroxyketal compounds such as 2,2-bis(4,4-ditert-amylperoxycyclohexyl)propane, 2,2-bis(4,4-ditert-hexylperoxycyclohexyl)propane, 2,2-bis(4,4-ditert-octylperoxycyclohexyl)propane, and 2,2-bis(4,4-dicumylperoxycyclohexyl)propane; hydroperoxide compounds such as cumene hydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide. dialkyl peroxide compounds such as 1,3-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene peroxide, tert-butylcumyl peroxide, and di-tert-butyl peroxide; diacyl peroxide compounds such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; peroxycarbonate compounds such as tert-butylperoxy-2-ethylhexanoate, tert-butylperoxybenzoate, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; organic peroxides such as peroxyester compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methyl)butyronitrile, and 1,1'-azobis(cyclohexane-1-carbonitrile).

The mass ratio [(A)/(b)] of the polyolefin resin (A) to the unsaturated monomer mixture (b) is preferably in the range of 5/95 to 40/60, more preferably 10/90 to 30/70, since this further improves the storage stability, adhesion and appearance of the resulting coating film.

The polyolefin-modified acrylic resin has a number average molecular weight (Mn) of preferably 3,000 to 50,000, more preferably 15,000 to 30,000, since this improves the storage stability and the appearance and adhesion of the resulting coating film. The weight average molecular weight (Mw) is preferably 30,000 to 300,000, more preferably 40,000 to 100,000. Here, the average molecular weight is a value calculated in terms of polystyrene based on gel permeation chromatography (hereinafter abbreviated as "GPC") measurements.

Examples of the terpene solvent include monoterpene hydrocarbons such as α-pinene, β-pinene, dipentene, limonene, turpentine, phellandrene, α-terpinene, γ-terpinene, terpinolene, myrcene, alloocimene, camphene, bornylene, paramenthene-1, paramenthene-2, paramenthene-3, paramentadiene, paramenthane, 2-carene, 3-carene, and thujane; monoterpene alcohols such as α-terpineol, β-terpineol, γ-terpineol, 4-terpineol, paramenthenol, paramenthanol, geraniol, linalool, nerol, citronellol, allocimenol, myrcenol, carveol, menthol, borneol, isoborneol, fenchyl alcohol, and verbenol; Examples of such terpene aldehydes include terpene aldehydes such as tetrahydrofuran and citronellal; terpene ketones such as isopulegone, carvone, and camphor (camphor white oil); terpene diols such as paramenthanediol; terpene ethers such as 1,4-cineole and 1,8-cineole; sesquiterpene hydrocarbons such as longifolene, caryophyllene, cadinene, thujopsene, cedrene, clobene, and longipinene; and sesquiterpene alcohols such as elemol, cadinol, and eudesmol. Among these, dipentene, limonene, camphor, and turpentine are preferred because they provide improved adhesion.

The content of the terpene solvent in the resin composition of the present invention is 50 to 500% by mass of the polyolefin-modified acrylic resin, but 100 to 300% by mass is preferred because this further improves storage stability, the appearance and adhesion of the resulting coating film.

The paint of the present invention contains the resin composition described above, but other additives such as solvents other than terpene solvents, defoamers, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, UV absorbers, antioxidants, leveling agents, and pigment dispersants can be used as blends. In addition, pigments such as titanium oxide, calcium carbonate, aluminum powder, copper powder, mica powder, iron oxide, carbon black, phthalocyanine blue, toluidine red, perylene, quinacridone, and benzidine yellow can also be used.

The paint of the present invention has high adhesion to plastic substrates and can therefore be suitably used as a paint for painting various plastic molded products. Examples of plastic molded products that can be painted with the paint of the present invention include the housings of electronic devices such as mobile phones, smartphones, tablet terminals, personal computers, digital cameras, and game consoles; the housings of home appliances such as televisions, refrigerators, washing machines, and air conditioners; and the interior materials of various vehicles such as automobiles and railway cars.

Methods for applying the coating material of the present invention include, for example, spray, applicator, bar coater, gravure coater, roll coater, comma coater, knife coater, air knife coater, curtain coater, kiss coater, shower coater, wheeler coater, spin coater, dipping, screen printing, etc. In addition, methods for forming a coating film after application include drying at room temperature to 120°C.

The present invention will be described in more detail below with reference to specific examples. The average molecular weight was measured under the following GPC measurement conditions.

[GPC measurement conditions]
Measurement device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used, connected in series.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (sample concentration 4 mg/mL in tetrahydrofuran solution)
Standard sample: A calibration curve was prepared using the following monodisperse polystyrene.

(Monodisperse polystyrene)
"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

(Synthesis Example 1: Synthesis of polyolefin-modified acrylic resin (1))
A flask equipped with a cooling tube, a thermometer, a dropping funnel, and a stirrer was charged with 100.0 parts by mass of maleic acid-modified polyolefin (manufactured by Nippon Paper Industries Co., Ltd., "Auroren 350S"; hereinafter, abbreviated as "polyolefin resin (A-1)"). butyl acetate 742.5 parts by mass, and methyl ethyl ketone 487.5 parts by mass, and the internal temperature was raised to 80 ° C. Next, after confirming the dissolution of the maleic acid-modified polyolefin, a mixture of 360.0 parts by mass of methyl methacrylate, 485.0 parts by mass of ethyl acrylate, 50.0 parts by mass of 2-hydroxypropyl methacrylate, 5.0 parts by mass of methacrylic acid, 250.0 parts by mass of methyl ethyl ketone, and 5.0 parts by mass of tert-butylperoxy 2-ethylhexanoate was added dropwise over 4 hours. One hour after the completion of the dropwise addition, a mixture of 5.0 parts by mass of methyl ethyl ketone and 2.0 parts by mass of tert-butyl peroxy 2-ethylhexanoate was added, and then a polymerization reaction was carried out for 10 hours while maintaining the internal temperature at 80° C. Next, a mixed solvent (butyl acetate/methyl ethyl ketone=50/50 (mass ratio)) was added so that the nonvolatile content was 40 mass%, and a solution of polyolefin-modified acrylic resin (1) was obtained.

(Synthesis Examples 2 and 3: Synthesis of Polyolefin-Modified Acrylic Resins (2) and (3))
Solutions of polyolefin-modified acrylic resins (2) and (3) were obtained in the same manner as in Synthesis Example 1, except that the compositions of the polyolefin resin and unsaturated monomer mixture used in Synthesis Example 1 were changed as shown in Table 1.

(Synthesis Example 4: Synthesis of polyolefin modified acrylic resin (R1))
A solution of polyolefin-modified acrylic resin (R1) was obtained in the same manner as in Synthesis Example 1, except that the compositions of the polyolein resin and unsaturated monomer mixture used in Synthesis Example 1 were changed as shown in Table 1.

The compositions of the polyolefin-modified acrylic resins (1) to (3) and (R1) obtained above are shown in Table 1.

The abbreviations in Table 1 are as follows.
Polyolefin resin (A-1): "Auroren 350S" manufactured by Nippon Paper Industries Co., Ltd.
Polyolefin resin (A-2): "Hardlen 14-LLB-P" manufactured by Toyobo Co., Ltd., chlorine content 27% by mass
MMA: methyl methacrylate HPMA: 2-hydroxypropyl methacrylate AA: acrylic acid EA: ethyl acrylate

(Example 1: Preparation and evaluation of resin composition (1))
15 parts by mass of the solution of polyolefin-modified acrylic resin (1) obtained in Synthesis Example 1 above (non-volatile content: 40% by mass) and 12 parts by mass of dipentene were blended to obtain a resin composition (1).

[Evaluation of storage stability]
The resin composition (1) was allowed to stand at 40° C. for one month, and the state of the solution was evaluated according to the following criteria.
◯: Neither separation nor precipitation was observed. △: Separation and/or precipitation was observed, but the mixture was easily dispersed by stirring. ×: Separation and/or precipitation was observed, and the mixture was not easily dispersed by stirring.

[Paint evaluation]
The resin composition (1) obtained above was diluted with a mixed solvent (butyl acetate/propylene glycol monomethyl ether acetate/ethyl acetate=75/10/15 (mass ratio); hereinafter abbreviated as "mixed solvent (1)") so that the viscosity was about 9 seconds (23°C) in "Viscosity Cup NK-2" manufactured by Anest Iwata Corporation, to prepare a paint (1).

[Preparation of coating film for evaluation]
The paint (1) obtained above was spray-coated onto a polypropylene substrate (50 mm x 50 mm) so that the film thickness after drying would be 5 to 10 μm, and the coating was dried by heating in a dryer at 70° C. for 30 minutes, and then dried at 25° C. for 1 day to prepare a cured coating film for evaluation.

[Evaluation of Coating Appearance]
The coating film for evaluation obtained above was visually observed, and the appearance of the coating film was evaluated according to the following criteria.
〇: No problem △: Slightly whitened ×: Significantly whitened

[Evaluation of Adhesion]
The coating film for evaluation obtained above was cut with a cutter to make the number of grids 1 mm wide, so that the number of grids was 100. Next, cellophane tape was applied so as to cover all the grids, and the operation of quickly peeling it off was repeated four times, and the adhesion was evaluated according to the following criteria from the number of grids remaining that were adhered.
○: 100 pieces △: 70-99 pieces ×: 69 pieces or less

(Examples 2 to 8: Preparation and evaluation of resin compositions (2) to (8))
Except for changing the composition of the polyolefin-modified acrylic resin (1) and the terpene solvent used in Example 1 as shown in Table 2, resin compositions (2) to (8) and paints (2) to (8) were obtained in the same manner as in Example 1, and each evaluation was performed.

(Comparative Examples 1 to 6: Synthesis of Resin Compositions (R1) to (R6))
Except for changing the composition of the polyolefin-modified acrylic resin (1) and the terpene solvent used in Example 1 as shown in Table 2, the resin compositions (R1) to (R6) and the coating materials (R1) to (R6) were obtained in the same manner as in Example 1, and each evaluation was performed.

The compositions and evaluation results of the polyolefin-modified acrylic resins (1) to (8) obtained above are shown in Tables 2 and 3.

The compositions and evaluation results of the polyolefin-modified acrylic resins (R1) to (R6) obtained above are shown in Table 4.

The abbreviations in Table 4 are as follows.
Swaclean 150: petroleum-based hydrocarbon solvent manufactured by Maruzen Petrochemical Co., Ltd. MCH: methylcyclohexane The terpene solvents used in the examples and comparative examples were manufactured by Nippon Terpene Chemical Co., Ltd.

It was confirmed that the resin compositions of the present invention in Examples 1 to 8 had excellent storage stability, and the resulting coating films had excellent coating appearance and adhesion.

On the other hand, Comparative Example 1 is an example in which the content of Perthane solvent relative to the polyolefin-modified acrylic resin is less than 50 mass %, which is the lower limit of the present invention, but it was confirmed that the adhesion was insufficient.

Comparative Example 2 is an example in which the content of Perthane solvent relative to the polyolefin-modified acrylic resin is greater than 500% by mass, which is the upper limit of the present invention, but it was confirmed that the appearance of the coating film was insufficient.

Comparative Example 3 is an example in which unmodified acrylic resin was used instead of polyolefin-modified acrylic resin, but it was confirmed that the adhesion was insufficient.

Comparative Examples 4 to 6 are examples in which the essential component terpene solvent was not used, but it was confirmed that the adhesion or coating appearance was insufficient.

Claims (3)

A resin composition containing a polyolefin-modified acrylic resin and a terpene solvent, wherein the polyolefin-modified acrylic resin is a reaction product of a polyolefin resin (A) and an unsaturated monomer mixture (b) containing an unsaturated monomer (b1) having a hydroxyl group, the mass ratio of the polyolefin resin (A) to the unsaturated monomer mixture (b) [(A)/(B)] being 5/95 to 60/40, the polyolefin resin (A) being a chlorinated polyolefin resin and/or a maleic acid-modified polyolefin resin, and the content of the terpene solvent being 100 to 500 mass% of the polyolefin-modified acrylic resin. A paint comprising the resin composition according to claim 1 . A plastic molded product coated with the paint according to claim 2 .