JP2003272443A - Semiconductive resin composition having releasability and cross-linkablity and power cable having external semiconductive layer consisting of the semiconductive resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive resin composition having both releasability and cross-linkablity and a power cable having an external semiconductive layer consisting of the semiconductive resin. <P>SOLUTION: The semiconductive resin composition having releasability and cross-linkablity consisting of an ethylene resin (A), carbon black (B), crosslinker (C), polymer peeling agent (D) and an unsaturated dimer of an α-aromatic substituted-α-methyl alkene (E) is provided as the external semiconductive layer with excellent releasability and mechanical properties of the power cable. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a releasable crosslinkable semiconductive resin composition and a power cable having an outer semiconductive layer made of the releasable crosslinkable semiconductive resin composition. More specifically, it is a releasable crosslinkable resin having excellent releasability and crosslinkability. Semiconducting resin composition and an electric power cable having an outer semiconducting layer comprising the same.

[0002]

2. Description of the Related Art Ethylene resins are excellent in electrical properties such as electrical insulation and high frequency properties, mechanical properties such as wear resistance, strength, low temperature brittleness, and workability such as extrusion moldability.
For example, it is widely used as an insulating coating material for electric wires and communication cables. Further, the crosslinked ethylene resin insulated power cable is composed of a conductor, an inner semiconductive layer, an insulating layer and an outer semiconductive layer from the inside to the outside, and these semiconductive layers are carbon black mixed with ethylene resin. However, a crosslinkable resin composition is used together with an insulating layer made of an ethylene-based resin in order to impart semiconductivity and ensure mechanical strength.

The inner semiconductive layer needs to have good adhesion and adhesiveness with the conductor and the insulating layer, but the outer semiconductive layer is peeled off from the crosslinked ethylene resin insulating layer. There is a demand for easy peeling without damaging the resin insulation layer. Therefore, a release agent is added to the crosslinkable semiconductive resin composition. However, the conventional release agents are not always sufficient in releasability, and there has been a demand for a releasable crosslinkable semiconductive resin composition having both excellent releasability and crosslinkability. In addition, Japanese Patent Laid-Open No. 4-675
Japanese Unexamined Patent Publication No. 10 describes that an unsaturated dimer of α-aromatic-substituted-α-methylalkene has an effect on scorch (suppression of premature crosslinking during extrusion) with respect to an ethylene resin. However, no mention is made of the effect on peelability.

[0004]

In view of the above problems, the present invention provides a releasable crosslinkable semiconductive resin composition having both excellent releasability and crosslinkability, and a power cable having an outer semiconductive layer formed thereof. The challenge is to provide.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polymer-based release agent conventionally used as a release agent is used as a scorch inhibitor. , The effect of imparting peelability is not substantially recognized by itself, but when blended with an unsaturated dimer of α-aromatic-substituted-α-methylalkene, the peelability is remarkably improved and increased. To find out that
The present invention has been completed.

That is, according to the first aspect of the present invention,
It consists of an ethylene resin (A), carbon black (B), a crosslinking agent (C), a polymer release agent (D), and an unsaturated dimer of α-aromatic group-substituted α-methylalkene (E). A releasable crosslinkable semiconductive resin composition is provided.

According to the second invention of the present invention, in the first invention, the blending amount of each component is such that the ethylene resin (A) 1
100 parts by weight of carbon black (B) 10-4
00 parts by weight, crosslinking agent (C) 0.1 to 5 parts by weight, polymer release agent (D) 2 to 50 parts by weight, and α-aromatic substitution-
Unsaturated dimer of α-methylalkene (E) 0.03 to
A releasable crosslinkable semiconductive resin composition comprising 4.5 parts by weight is provided.

According to a third invention of the present invention, in the first or second invention, the polymer-based releasing agent (D) is an unsaturated dimer of nitrile butadiene rubber and α-aromatic group-substituted α-methylalkene. Provided is a releasable crosslinkable semiconductive resin composition, wherein (E) is 2,4-diphenyl-4-methylpentene-1 represented by the following chemical formula 1.

[0009]

[Chemical 2]

According to a fourth aspect of the present invention, there is provided a power cable having an outer semiconductive layer made of the peelable crosslinkable semiconductive resin composition according to any one of the first to third aspects.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the peelable crosslinkable semiconductive resin composition of the present invention and a power cable having an outer semiconductive layer made of the same will be described in detail for each item.

1. Ethylene Resin (A) As the ethylene resin used in the present invention, ethylene homopolymer, ethylene-α-olefin (having 3 to 1 carbon atoms)
2) Copolymers, ethylene-α, β-unsaturated carboxylic acid (or ester derivative thereof) copolymers, ethylenecarboxylic acid vinyl ester copolymers, and the like, specifically, produced by a high-pressure radical polymerization method. High-pressure low-density polyethylene, high-pressure medium-density polyethylene, high-pressure high-density polyethylene, ethylene-ethyl acrylate copolymer,
Examples thereof include ethylene-butyl acrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer and the like. Furthermore, temperature 0-250
℃, pressure 50MPa or more (high pressure), 10-50M
Solution polymerization method, suspension polymerization method, under conditions of either Pa (for medium pressure) or normal pressure to 10 MPa (for low pressure).
A linear low density (or ultra-high density) produced by a method such as a slurry polymerization method or a gas phase polymerization method using a Ziegler catalyst, a Phillips catalyst, a standard catalyst or a single site (also called metallocene or Kaminsky) catalyst. (Low density) ethylene-butene-1 copolymer which is ethylene-α-olefin copolymer, ethylene-hexene-
1 copolymer, an ethylene-octene-1 copolymer, etc. can be illustrated.

The melt mass flow rate of the ethylene resin (A) is 2 to 1000 g / 10 minutes, preferably 10 to 4 in order to satisfy the workability and mechanical properties of the molded product.
00 g / 10 minutes, more preferably 12 to 50 g / 10
Minutes can be preferably used. The ethylene resin (A) has a comonomer content of 5 to 5 in the above.
45% by weight, preferably 15-30% by weight of ethylene-
A vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and a linear low-density ethylene-α-olefin copolymer having a density of 0.88 to 0.91 g / cm ³ are blended with other components such as carbon black. It is preferable because it has good compatibility with the agent.
The ethylene-based resin (A) may be used alone or in combination of two or more.

2. Carbon Black (B) The carbon black (B) used in the present invention acts as a conductive material and imparts semiconductivity to the peelable crosslinkable semiconductive resin composition of the present invention. The carbon black (B) may be any known carbon black and is not particularly limited. For example, graphitized carbon, furnace black,
Examples include acetylene black and Ketjen black. The blending amount of carbon black (B) is 10 to 400 parts by weight, preferably 30 to 150 parts by weight, and more preferably 40 to 120 parts by weight with respect to 100 parts by weight of the ethylene resin (A). If the blending amount of carbon black (B) is less than 10 parts by weight, the conductivity required for the semiconductive layer of the power cable cannot be imparted, while if it exceeds 400 parts by weight, the processing during coating is performed. And the mechanical properties of the semiconductive layer are insufficient, which is not desirable. The carbon black (B) may be used alone or in combination of two or more.

3. Cross-Linking Agent (C) The cross-linking agent (C) used in the present invention is added to the ethylene-based resin (A) under heating so as to generate free radical sites and cross-link them. There is no particular limitation as long as they are known ones such as compounds, peresters and azo compounds. Specifically, 1,1-bis-t
-Butylperoxycyclohexane, 2,2-bis-t
-Butylperoxybutane, dicumyl peroxide,
2,5-Dimethyl-2,5-di-t-butylperoxyhexane, t-butylcumylperoxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-
3, α, α′-bis (t-butylperoxy) diisopropylbenzene, di-t-butylperoxide, diisopropylbenzene hydroperoxide and the like can be mentioned. Among these, α, α′-bis (t-butylperoxy) diisopropylbenzene, from the viewpoint of ease of use such as actual use and decomposition temperature for obtaining a one-minute half-life,
Dicumyl peroxide can be preferably used.

The amount of the cross-linking agent (C) compounded is 0.1 to 5 parts by weight, preferably 0.5 to 2.5 parts by weight, based on 100 parts by weight of the ethylene resin (A). This blending amount is 0.
If it is less than 1 part by weight, effective cross-linking cannot be obtained. On the other hand, if it exceeds 5 parts by weight, gel or the like is generated, the uniformity of electrical properties such as semiconductivity begins to deteriorate, and surface roughness occurs, which is preferable. Absent. The crosslinking agent (C) may be used alone or in combination of two or more.

4. Polymer-based release agent (D) The polymer-based release agent (D) used in the present invention may be any known release agent commonly used as a polymer-based release agent for a releasable crosslinkable semiconductive resin composition. , There is no particular limitation. For example, nitrile butadiene rubber, polyorganopolysiloxane, polypropylene, styrene butadiene rubber, polystyrene, nylon, chlorinated polyethylene, chloroprene rubber, high vinyl acetate group-containing ethylene-
A vinyl acetate copolymer etc. are illustrated. Of these, nitrile butadiene rubber is particularly preferable because it has an excellent balance of dispersibility with the ethylene resin (A) and releasability.

The amount of the polymeric release agent (D) compounded is 2 to 50 parts by weight, preferably 4 to 20 parts by weight, based on 100 parts by weight of the ethylene resin (A). This blend amount is 2
If it is less than the weight part, effective peelability cannot be imparted. On the other hand, if it exceeds 50 parts by weight, it becomes difficult to uniformly disperse the polymer-based release agent (D) in the resin composition, and the uniformity of electrical characteristics begins to deteriorate, which is not preferable. In addition,
The polymer-based release agent (D) may be used alone or in combination of two or more.

5. Unsaturated Dimer of α-Aromatic Substituted-α-Methylalkene (E) The unsaturated dimer of α-aromatic substituted-α-methylalkene (E) used in the present invention is represented by the following chemical formula 2 It is an unsaturated dimer obtained by dimerizing an α-aromatic-substituted α-methylalkene monomer having a chemical structural formula as shown below as a raw material.

[0020]

[Chemical 3] (In the formula, R represents an aryl group, an alkaryl group, a halogen-substituted aryl group or a halogen-substituted alkaryl group.)

Specific examples of the α-aromatic-substituted α-methylalkene monomer include α-methylstyrene, p-methyl-α-methylstyrene, p-isopyropyl-α-methylstyrene and m-methyl-α-methylstyrene. Styrene, dimethyl-α-methylstyrene, chloro-α-methylstyrene, chloromethyl-α-methylstyrene, diethyl-α
-Methyl styrene, methyl isopropyl-α-methyl styrene, p-bromo-α-methyl styrene, p-chloro-α-methyl styrene, p-cyano-α-methyl styrene, p-nitro-α-methyl styrene, p- Amino-α
-Methylstyrene, p-hydroxy-α-methylstyrene, p-methoxy-α-methylstyrene, p-ethoxy-α-methylstyrene, pn-butoxy-α-methylstyrene, pt-butoxy-α- Methyl styrene, p
-Allyloxy-α-methylstyrene, p-benzyloxy-α-methylstyrene, p-phenyloxy-α-methylstyrene, pt-butyl-α-methylstyrene, p-
Phenyl-α-methylstyrene, p-benzyl-α-methylstyrene, m-bromo-α-methylstyrene, m-
Chloro-α-methylstyrene, m-cyano-α-methylstyrene, m-nitro-α-methylstyrene, m-amino-α-methylstyrene, m-hydroxy-α-methylstyrene, m-methoxy-α-methyl. Styrene, m-ethoxy-α-methylstyrene, m-n-butoxy-α-
Methylstyrene, m-t-butoxy-α-methylstyrene, m-allyloxy-α-methylstyrene, m-benzyloxy-α-methylstyrene, m-phenyloxy-α-
Examples thereof include methylstyrene, m-t-butyl-α-methylstyrene, m-phenyl-α-methylstyrene, m-benzyl-α-methylstyrene and the like.

Among these, α-represented by the chemical formula 1
Unsaturated dimers of methylstyrene, namely 2,4-diphenyl-4-methylpentene-1 and 2,4-di (p-methylphenyl) -4-methylpentene-1 represented by Chemical Formula 3, are also available. Easy and preferred.

[0023]

[Chemical 4]

[0024]

[Chemical 5]

The amount of the unsaturated dimer (E) of α-aromatic-substituted-α-methylalkene is 1 wt% of the ethylene resin (A).
It is 0.03 to 4.5 parts by weight, preferably 0.05 to 4 parts by weight, based on 00 parts by weight. This compounded amount is 0.03
If the amount is less than the amount by weight, the releasability of the polymer-based release agent (D) cannot be effectively increased. On the other hand, if it exceeds 4.5 parts by weight, the releasability is effectively increased but the degree of crosslinking is affected, which is not preferable. Note that α-aromatic substitution-α
The unsaturated dimer (E) of methylalkene may be used alone or in combination of two or more.

6. Other Compounds In addition to the above-mentioned components, various other additives and auxiliary materials can be compounded in the peelable crosslinkable semiconductive resin composition of the present invention within a range not impairing the object of the present invention. As various additives and auxiliary materials, stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, nucleating agents, lubricants, fillers,
Dispersant, copper damage inhibitor, metal deactivator, neutralizer, flame retardant,
Examples thereof include processing aids, mold release agents, foaming agents, foam inhibitors, coloring agents, bactericides, and fungicides.

It is preferable to add an antioxidant to the peelable crosslinkable semiconductive resin composition of the present invention. Examples of the antioxidant include phenol-based, phosphorus-based, amine-based, and sulfur-based antioxidants, which may be used alone or as a mixture of two or more thereof, and the compounding amount thereof is 100% by weight of the base resin (A). It is about 0.001 to 5 parts by weight with respect to parts. Further, the peelable crosslinkable semiconductive resin composition of the present invention contains a small amount of other olefinic resin within a range not impairing the characteristics of the present invention in addition to the ethylene resin (A) depending on the purpose of use. You can also do it.

7. Preparation of releasable crosslinkable semiconductive resin composition The releasable crosslinkable semiconductive resin composition of the present invention comprises a predetermined amount of the above-mentioned ethylene resin (A), carbon black (B), crosslinking agent (C) and polymer. The system stripping agent (D), and the unsaturated dimer of the α-aromatic-substituted α-methylalkene (E), and an appropriate amount of the other compounding ingredients are blended, and a general method such as kneader or Banbury mixer is used. Using a continuous mixer or a single-screw or twin-screw extruder, uniformly, below the decomposition temperature of the cross-linking agent, for example 110
It can be prepared by melt-kneading at 130 ° C. For carbon black (B), polymer-based release agent (E), and other compounds, a masterbatch is prepared by using the ethylene-based resin (A) used in the present invention, compounded and melt mixed. But of course it is good.

In addition, the cross-linking agent (C) may be difficult to process because the resin itself may be cross-linked when it is melt-kneaded with the resin at the decomposition temperature or higher, and therefore, the peelable semi-conductive material excluding the cross-linking agent (C). The resin composition is melt-kneaded, for example, at 110 to 200 ° C. in the same manner as in the above-mentioned general method, granulated into pellets, placed in a closed container together with the cross-linking agent (C), and sealed, at room temperature or as necessary. For example, the pellet surface is coated with the cross-linking agent (C) or the pellet surface by heating to an arbitrary temperature of up to about 50 to 100 ° C. (however, less than the melting temperature of the ethylene resin (A)) and shaking for 6 hours to 1 day. Can be impregnated into pellets to prepare the peelable crosslinkable semiconductive resin composition of the present invention. The peelable crosslinkable semiconductive resin composition of the present invention is preferably a pellet having an average particle diameter of 2 to 7 mm in terms of workability in coating processing so as to be suitably used as an outer semiconductive layer of a power cable.

[0030]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. The evaluations used in this specification are based on the following methods.

"Evaluation" 1. As a peelable model insulating layer, HFDJ-4201 (high pressure method low density polyethylene, melt mass flow rate 3.2 g / 10, manufactured by Nippon Unicar Co., Ltd.) of a crosslinkable insulating composition for power cables.
Min, density 0.92 g / cm ³ ) at a temperature of 120 ° C., 15
The sheet was press-molded at a pressure of MPa for 5 minutes to form a sheet having a thickness of 2 mm. The peelable crosslinkable semiconductive resin compositions obtained in Examples and Comparative Examples were similarly used to prepare test sheets having a thickness of 2 mm. The model insulation layer sheet and the test sheet are overlaid, preheated at 120 ° C, then at 180 ° C, 20
It was heated and pressed at a pressure of MPa for 25 minutes to prepare a laminated sheet having a thickness of 3 mm, which was punched into a width of 12.7 mm and a length of 125 mm to obtain a test piece. One piece of the test piece is peeled off by about 25 mm in advance, and the model insulating layer sheet portion and the test sheet are fixed by two gripping devices with a tensile tester, and both sheets are peeled by pulling vertically at a pulling speed of 500 mm / min. The required strength was measured as the peel strength, and less than 25 N / cm was regarded as acceptable.

2. Crosslinking degree The degree of crosslinking was determined according to JIS C-3005, and the gel fraction was calculated as the crosslinking degree. A degree of crosslinking of 70% or more was passed.

Example 1, Comparative Example 1 Ethylene-vinyl acetate copolymer of ethylene resin (A) (melt mass flow rate 20 g / 10 minutes, vinyl acetate comonomer content 20% by weight) was added to 100 parts by weight of carbon. 95 parts by weight of furnace black as the black (B) and 10 parts of nitrile butadiene rubber as the polymer release agent (D).
Parts by weight, 1 part by weight of 2,4-diphenyl-4-methylpentene-1 as the unsaturated dimer (E) of α-aromatic-substituted-α-methylalkene, tetrakis [methylene-3- (3)- 1 part by weight of (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane was added to a Banbury mixer, and the mixture was stirred at 160 to 170 ° C. for 5 hours.
After melt-kneading for a minute, the mixture was granulated into pellets having an average particle size of 4 mm. The obtained semiconductive resin composition was placed in a closed container, and the amount of 1.
The cross-linking agent (C), α, α′-bis (t-butylperoxy) diisopropylbenzene, was added to 5 parts by weight, and the mixture was sealed and stirred at room temperature for 1 day. A resin composition was obtained. Comparative Example 1 was carried out in the same manner as in Example 1 except that 1 part by weight of 2,4-diphenyl-4-methylpentene-1 as the unsaturated dimer (E) of α-aromatic-substituted-α-methylalkene was not added. To obtain a releasable crosslinkable semiconductive resin composition. The releasability and the degree of crosslinking of the obtained releasable crosslinkable semiconductive resin composition are shown in Table 1. In Example 1, the peel strength was as small as 9 N / cm and was good, and the degree of crosslinking was 78%. It had both releasability and crosslinkability, but Comparative Example 1
Although the degree of cross-linking passed, the peel strength was as large as 30 N / cm and the peelability was unacceptable.

[Examples 2 and 3, Comparative Examples 2 and 3] Incorporation of 2,4-diphenyl-4-methylpentene-1 which is an unsaturated dimer (E) of α-aromatic-substituted α-methylalkene. Examples except that the amounts were changed to 0.1 parts by weight [Example 2], 3 parts by weight [Example 3], 0.01 parts by weight [Comparative Example 2], and 5 parts by weight [Comparative Example 3]. A releasable crosslinkable semiconductive resin composition was obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The composition of the composition and the evaluation results are shown in Table 1.
The peel strengths of Examples 2 and 3 are 12 N / cm and 8 N.
/ Cm, and the degree of crosslinking is 80% and 75%, respectively
Although the peelability and the crosslinkability were both obtained in Comparative Example 2, the peel strength was 28 N / cm in Comparative Example 2, and the peel strength was 7 N / cm in Comparative Example 3. Was 55%, which was unacceptable, and the composition did not have these evaluation characteristics.

[0035]

[Table 1]

[Examples 4 and 5 and Comparative Example 4] The compounding amount of the nitrile-butadiene rubber of the polymer-based release agent (D) was 5 parts by weight [Example 4], 30 parts by weight [Example 5], and none. A peelable crosslinkable semiconductive resin composition was obtained in the same manner as in Example 1 except that the composition was changed to [Comparative Example 4], and evaluated in the same manner as in Example 1. The composition of the composition and the evaluation results are shown in Table 1. The peel strengths of Examples 4 and 5 were 14 N / cm and 5 N / cm, and the degree of crosslinking was 76% and 8 respectively.
It passed 2% and had both peelability and crosslinkability,
The peel strength of Comparative Example 4 without compounding is 50 N / cm and the peelability does not pass, and the unsaturated dimer of the α-aromatic-substituted α-methylalkene (E) alone cannot provide effective peelability. I showed that.

[Example 6 and Comparative Example 5] A linear ethylene-octene-1 copolymer (melt mass flow rate 5 g / 10 minutes, density 0.87 g / c) was used as an ethylene resin (A).
A peelable crosslinkable semiconductive resin composition was obtained in the same manner as in Example 1 and Comparative Example 1 except that m ³ ) was used, and the same evaluation was performed.
The composition and the evaluation results of the composition are shown in Table 2. The peel strength of Example 6 was 22 N / cm, and the degree of crosslinking was 77, which was both peelable and crosslinkable. In Example 5, the peel strength was 40 N / cm, which did not pass, and the degree of crosslinking passed, but the peelability was insufficient.

[0038]

[Table 2]

[0039]

As described in detail above, the present invention is
It has been newly found that the unsaturated dimer of α-aromatic-substituted-α-methylalkene (E) is remarkably improved in the releasability when used in combination with the conventionally used polymer-based release agent (D). Based on the effect obtained, the ethylene resin (A), the carbon black (B), the crosslinking agent (C), the polymer release agent (D), and the α-aromatic group-substituted α-methylalkene of the present invention are used. The releasable crosslinkable semiconductive resin composition consisting of the unsaturated dimer (E) has suitable releasability and can reduce the compounding amount of the polymer-based release agent (D). The influence can be almost eliminated, and crosslinkability can be provided. Further, the processability and mechanical properties of the ethylene resin (A) itself can be secured. Therefore, the peelable crosslinkable semiconductive resin composition of the present invention is of a good quality having the necessary properties and processability as an outer semiconductive layer of a power cable, and a good peelable crosslinked outer semiconductive layer having a higher quality than this. It is possible to obtain an electric wire cable having

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromitsu Okumura             2-2-6, Saito, Konan-ku, Yokohama-shi, Kanagawa             410 (72) Inventor Makoto Okazawa             6-13 Kaminocho, Sakae Ward, Yokohama City, Kanagawa Prefecture (72) Inventor Yumi Oki             1-10-5, Kyomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa             601 F-term (reference) 5G301 DA18 DA42 DA43 DD04

Claims (4)

[Claims] 1. An ethylene-based resin (A), carbon black (B), a cross-linking agent (C), a polymer-based release agent (D), and an unsaturated dimer of α-aromatic group-substituted α-methylalkene ( A releasable crosslinkable semiconductive resin composition comprising E). 2. A blending amount of each component is carbon black (B) with respect to 100 parts by weight of ethylene resin (A).
10 to 400 parts by weight, 0.1 to 5 parts by weight of the cross-linking agent (C),
2 to 50 parts by weight of the polymer-based releasing agent (D), and an unsaturated dimer (E) of .alpha.-aromatic-substituted .alpha.-methylalkene (E).
The peelable crosslinkable semiconductive resin composition according to claim 1, which is from 03 to 4.5 parts by weight. 3. The polymer-based release agent (D) is nitrile butadiene rubber, and the unsaturated dimer (E) of α-aromatic group-substituted α-methylalkene is represented by the following chemical formula 1,2-
The releasable crosslinkable semiconductive resin composition according to claim 1 or 2, which is diphenyl-4-methylpentene-1. [Chemical 1] 4. A power cable having an outer semiconductive layer made of the peelable crosslinkable semiconductive resin composition according to claim 1.