KR20200083687A - Long fiber reinforced thermoplastic resin composition having excellent thermal conductivity and EMI shielding property and molded article comprising the same - Google Patents

Abstract

The present invention relates to a long fiber reinforced thermoplastic resin composition excellent in heat dissipation and electromagnetic shielding properties, and a molded article manufactured therefrom. More particularly, the present invention relates to: a long fiber reinforced thermoplastic resin composition capable of simultaneously achieving high thermal conductivity properties by using graphene oxide as a heat dissipating filler, and implementing excellent mechanical properties and electromagnetic shielding properties by including a specific content of a thermoplastic resin, long carbon fiber and a thermal stabilizer; and a molded article comprising the composition.

Description

Long fiber reinforced thermoplastic resin composition having excellent thermal conductivity and EMI shielding property and molded article comprising the same}

The present invention relates to a long fiber-reinforced thermoplastic resin composition excellent in heat dissipation and electromagnetic wave shielding properties, and a molded article manufactured therefrom, more specifically, excellent mechanical properties and electromagnetic waves by including a specific content of a thermoplastic resin, a carbon long fiber, and a heat stabilizer It relates to a long fiber-reinforced thermoplastic resin composition capable of simultaneously achieving high thermal conductivity properties by implementing shielding properties and using graphene oxide as a heat dissipating filler, and a molded article comprising the same.

Since the metal material diffuses heat energy applied by the surrounding environment at a high speed, it is possible to protect electronic components sensitive to heat in a high temperature environment locally, and to achieve high mechanical stiffness, but electromagnetic waves operated by metal materials As described above, the effectiveness of the shielding is insufficient to realize effective shielding of electromagnetic waves generated inside the device mainly due to the reflection action, and continuous productivity and post-processing for mass production of products of complex and various designs. The cost is high, and there is a limit to realizing a lightweight material due to its high density.

In order to overcome these shortcomings, research on various thermally conductive thermoplastic materials has been developed. Recently, more heat and electromagnetic waves are generated in the device due to high integration and high performance of the electronic device. In particular, as the electronic/informatization environment continues to develop, the use of high-frequency bands increases, and as the output of electromagnetic waves by high-density devices increases, electromagnetic interference occurs in a wider frequency range than in the past, which is industrial, military, and environmental. It has become a big issue in terms of aspect. For this reason, there is an increasing demand for a heat dissipation material that rapidly spreads heat and electromagnetic waves generated in an environment around the material so as not to be exposed to the heat environment or to block electromagnetic waves, or a thermoplastic material that implements an electromagnetic wave shielding function.

In addition, in the development of such a thermoplastic heat dissipation material, the flow characteristics and heat resistance characteristics of the thermoplastic resin are very important factors.

Studies on thermoplastic resins for applying various industrial issues and heat dissipation materials have been continuously conducted. For example, Korean Patent Publication No. 10-2002-0096356 discloses a method of manufacturing a thermally conductive thermoplastic resin by adding less than 25% by volume of ceramic solids as a heat dissipating filler to a thermoplastic resin. The disadvantages are that the conductivity is significantly reduced and the thermal conductivity of the injection material is insufficient.

Korean Patent Publication No. 2007-0135608 discloses a resin composition in which graphite, a ceramic filler, and a fibrous inorganic filler are mixed with a thermoplastic resin. However, this technology has a disadvantage in that it is difficult to impart high thermal conductivity characteristics because it has a limitation in graphite input by using a carbon-based filler and ceramics in order to impart insulating properties, and thus it is difficult to apply to parts requiring high thermal conductivity. Also, in terms of material recycling, there are disadvantages than the heat dissipation filler single system.

Republic of Korea Patent Publication No. 2012-0078256 discloses a high thermal conductivity resin composition using graphite as a heat dissipating filler and a mixture of glass fibers and carbon fibers as a fibrous inorganic filler, but because the inorganic filler is mixed, thermoelectric injection material is used. There is a disadvantage that the improvement of the conductivity is insufficient.

Japanese Laid-Open Patent Publication No. 2002-146187 discloses a thermally conductive resin composition having excellent fluidity by using alumina as a heat dissipating filler, but because it uses alumina with low heat dissipation effect, the thermal conductivity of the injection material is 1 W/m·K. As a result, the advantage of heat dissipation is insufficient, and the cost of alumina is high, so the price of plastic injection material increases.

Japanese Patent Application Publication No. 2003-336956 discloses a resin composition in which a thermoplastic resin is mixed with a silane-based compound and graphite as a heat dissipating filler. However, this technology has the disadvantage that the heat conductivity is 4 W/m·K, and the advantage of the heat dissipation property is insufficient by reducing the amount of heat dissipating filler to maintain high mechanical strength.

Accordingly, development of a thermoplastic resin composition that realizes high thermal conductivity and electromagnetic wave shielding properties and simultaneously implements mechanical properties is still required.

The present invention is to solve the problems of the prior art described above, by implementing excellent mechanical properties and electromagnetic wave shielding properties, by using graphene oxide as a heat dissipative filler, long fiber-reinforced thermoplastic resin capable of simultaneously achieving high thermal conductivity properties It is a technical task to provide a composition and a molded article comprising the same.

In order to solve the above technical problem, the present invention is based on 100 parts by weight of the total resin composition, (A) 50 to 90 parts by weight of thermoplastic resin, (B) 0.05 to 1 part by weight of graphene oxide, (C) 10 to 10 carbon fibers A long fiber-reinforced thermoplastic resin composition is provided, comprising 48 parts by weight and (D) 0.1 to 5 parts by weight of a heat stabilizer.

According to another aspect of the present invention, a molded article comprising the long fiber-reinforced thermoplastic resin composition is provided.

Long fiber-reinforced thermoplastic resin composition according to the present invention has high thermal conductivity and electromagnetic wave shielding properties, and exhibits excellent pressure/injection moldability and mechanical properties, and is also inexpensive to manufacture. Molded products can be manufactured at low cost, and these molded products can be used in various fields, such as automobiles, electric, electronic components, and LED lighting.

Hereinafter, the present invention will be described in detail for each component.

The long fiber-reinforced thermoplastic resin of the present invention refers to a fiber in which a long fiber is hung on a pultrusion molding apparatus, and the resin is “coated” through an impregnation tank in which the resin is melted, and the long fiber-reinforced thermoplastic resin composition is final. It is manufactured in the form of pellets, so long fibers are reinforced parallel to the length direction of the pellets, and can be produced in 5 to 30 mm depending on the length of the pellets.

In order to solve the above technical problem, the present invention, (A) 50 to 90 parts by weight of a thermoplastic resin, (B) 0.05 to 1 part by weight of graphene oxide, (C) 10 to 48 parts by weight of carbon long fibers, and (D) heat It is characterized by including a stabilizer.

(A) Thermoplastic resin

The thermoplastic resin used in the resin composition of the present invention is not particularly limited.

However, since the flow property of the resin is closely related to the impregnation rate of the carbon long fibers that can realize the heat dissipation property, the higher the fluidity of the thermoplastic resin, the higher the impregnation of the same filler, thereby exhibiting high heat dissipation properties. It is advantageous.

General-purpose plastics as such thermoplastic resins include polystyrene, polyethylene, polypropylene polyamide (nylon 6, nylon 66, nylon 12, etc.), polyester resins (polybutylene terephthalate, polyethylene terephthalate, etc.), polyphenylene oxide, and the like. Polyarylene oxide-based resin, polycarbonate-based resin, and polyphenylene sulfide resin, thermotropic liquid crystal polymer, aromatic polyamide, polyarylate, polysulfone, polyether sulfone, polyetherimide, thermotropic liquid crystal polymer resin, Polyether ketone, and the like.

For example, as the thermoplastic resin, a polyamide having a number average molecular weight of 17,000 or less, a polycarbonate having a number average molecular weight of 20,000 or less, a polyester having a number average molecular weight of 23,000 or less, or a mixture thereof can be used.

Preferably, in the present invention, a polyamide resin having a number average molecular weight (Mn) of 7,000 to 17,000 may be used in consideration of fluidity. It may be preferably 9,000 to 17,000, more preferably 10,000 to 13,000, even more preferably 11,000 to 12,000. In addition, a polycarbonate resin having a number average molecular weight of 10,000 to 20,000, preferably 12,000 to 19,000, more preferably 13,000 to 18,000, and even more preferably 15,000 to 17,500 can be used. In addition, a polyester resin having a number average molecular weight of 15,000 to 23,000, preferably 16,000 to 22,000, more preferably 18,000 to 21,000, and even more preferably 19,000 to 20,500 can be used.

When the number average molecular weight of the thermoplastic resin, that is, the polyamide resin, the polycarbonate resin or the polyester resin is lower than the numerical range, it is difficult to secure mechanical properties, and when it exceeds the numerical range, fluidity and weather resistance may be deteriorated.

As the polyamide resin, a lactam having a ring structure, w-amino acid, or a product prepared by condensation polymerization of two or more of them may be used, and diacids and diamines may be used as monomers.

As the polyamide resin, a homopolyamide, copolyamide or a mixture thereof can be used. Further, the polyamide resin may be crystalline, semi-crystalline, or amorphous resin.

In one embodiment of the present invention, the polyamide resin is specifically, poly hexamethylenediamine adiamide (nylon 6,6), polyhexamethylenediamine sebacamide (nylon 6,10), polyhexamethylene lauroamide (Nylon 6,12), polytetramethylenediamine adipamide (nylon 4,6), polycaprolactam (nylon 6), polylaurolactam (nylon 12), or a mixture thereof.

Within 100 parts by weight of the resin composition of the present invention, the thermoplastic resin is included in an amount of 50 to 90 parts by weight, more preferably 55 to 88 parts by weight, even more preferably 58 to 88 parts by weight. . When the content of the thermoplastic resin in 100 parts by weight of the resin composition is less than 50 parts by weight, there may be a problem that processability and injection moldability are not secured. Conversely, when the content of the thermoplastic resin is more than 90 parts by weight, electromagnetic shielding, thermal conductivity The content of additives for improving physical properties such as weatherability or other physical properties such as weather resistance and thermal stability is relatively reduced, and thus there may be a problem of deterioration in overall physical properties.

The lower limit of the thermoplastic resin content may be, for example, 50 parts by weight or more, 55 parts by weight or more, 60 parts by weight or more, 65 parts by weight or more, 70 parts by weight or more, or 75 parts by weight or more, and an upper limit of 90 parts by weight or less , 85 parts by weight or less, 80 parts by weight or less, 75 parts by weight or less, 70 parts by weight or less, or 65 parts by weight or less.

(B) Graphene Oxide

Graphene has a unique structure in which two carbon atoms have double bonds, and in addition to the sigma bonds directly connecting the carbon atoms, there are pi bonds connected with p-orbitals protruding up and down the carbon atoms. When the double bond of the carbon atom is further expanded, the overlap of the p-orbital is also expanded. The hexagonal net-like carbon atoms constituting graphene are also connected by overlapping pi-bonds, as in the case of benzene. Since free electrons can move in the p-orbital overlapping between adjacent carbon atoms, graphene has excellent electrical conductivity.

As a method of synthesizing graphene, a mechanical exfoliation method (top-down method) in which a single layer graphene is separated from graphite using a scotch tape, a chemical exfoliation method in which graphene oxide is synthesized by reduction using a reducing agent or by heat treatment, high temperature In a chemical vapor deposition method (bottom-up) that grows from carbon atoms by using a transition metal that adsorbs nitrogen well as a catalyst layer, carbon that is adsorbed or contained in crystals at high temperature is grown into graphene along the texture of the surface. Epitaxy synthesis methods and the like are widely known.

Graphene synthesized by a conventional method as described above has low yield and is difficult to apply to a resin composition because it is obtained in the form of a thin film film. Therefore, in the present invention, a graphene oxide capable of maintaining a stable yield and shape sufficient to be put in an extruder is used. According to a preferred embodiment of the present invention, graphene oxide is produced using a solvent heat synthesis. According to the solvent heat synthesis method in this embodiment, sodium (ethanol) and ethanol (ethanol) are first placed in a reaction vessel at a molecular ratio of 1:1 and introduced into a furnace to react at 220° C. for 72 hours, and then the produced lead material After heat treatment for a short time, washed with distilled water, and dried in a vacuum oven at 100° C. for 24 hours to obtain graphene oxide.

Although graphene oxide has excellent thermal conductivity, it is difficult to mass-synthesize it, production cost is high, bulk density is too low, and the input ability to the extruder is also reduced by the van der Waals force between particles. Therefore, in the present invention, graphene oxide is not used alone, and a small amount of graphene oxide is used in combination with graphite to prevent loss during input to the extruder, facilitate input, and increase processability to increase high thermal conductivity. It is possible to extrude while maintaining the.

In the present invention, it is preferable that the particle diameter of the graphene oxide is 1 to 10 μm, and the thermal conductivity is usually 4500 to 5500 W/m·k.

Within 100 parts by weight of the resin composition of the present invention, the graphene oxide is contained in 0.05 to 1 part by weight, preferably 0.1 to 1 part by weight, even more preferably 0.5 to 1 part by weight. If the graphene oxide content in the composition is less than 0.05 parts by weight, the effect of improving thermal conductivity is negligible, and if it exceeds 1 part by weight, the volume becomes large and the weight of the extruded strand becomes light, making the continuous process difficult.

The lower limit of the graphene oxide content may be, for example, 0.05 parts by weight or more, 0.07 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more, and the upper limit is 1 part by weight Or less, 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, 0.6 parts by weight or less, or 0.55 parts by weight or less.

(C) Carbon Long fibers

The long carbon fiber may be surface-treated, and a silane-based or titanate-based low-molecular-weight or high-molecular-weight polymer commonly used as a surface treatment agent may be used. At least one of the surface treatment agents is preferably a surface treatment agent having good affinity with the thermoplastic resin, and can be continuously impregnated with the thermoplastic resin by various known methods such as a melt impregnation method and a powder charging method.

The long carbon fiber may be focused with a urethane resin.

Although not particularly limited, in the present invention, a long fiber-reinforced thermoplastic resin composition may be prepared and used in a pellet form using a pultrusion method in consideration of mass productivity and efficiency among various known methods. For example, the thermoplastic resin composition is introduced into the resin injection part of a pultrusion equipment, and impregnated with long carbon fibers in the form of a lobe while passing through the die, through the process of pulling and squeezing, and the continuous strand in the impregnated state It is cooled by drawing (pultrusion) and cut into pellets to prepare a long fiber-reinforced thermoplastic resin composition in pellets.

Within 100 parts by weight of the resin composition of the present invention, the carbon long fibers are included in an amount of 10 to 48 parts by weight, more preferably 15 to 45 parts by weight, even more preferably 18 to 40 parts by weight have. When the content of carbon long fibers in 100 parts by weight of the resin composition is less than 10 parts by weight, the effect of improving mechanical stiffness and thermal conductivity may be negligible. Conversely, when the content of carbon long fibers is more than 48 parts by weight, impact modifiers and heat Since the input amount of the stabilizer and other additives is limited, impact resistance and weather resistance are deteriorated, processability is poor, and carbon long fibers may be drawn to the thermoplastic resin surface, or dispersion of the long carbon fibers in the injection molded article may be uneven.

The lower limit of the content of the long carbon fiber may be, for example, 10 parts by weight or more, 12 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, or 30 parts by weight or more, and an upper limit of 48 parts by weight Or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less.

(D) heat stabilizer

The resin composition of the present invention includes a heat stabilizer to improve heat resistance and weather resistance.

In general, primary heat stabilizers are designed to absorb radicals. In addition, in order to improve the processing stability of the primary heat stabilizer and to apply harsh processing conditions, a secondary heat stabilizer to which phenol, sulfur, or phosphorus is applied may be used in combination. In the present invention, a heat stabilizer is used to perform a role similar to that of the secondary heat stabilizer. The type of the heat stabilizer is not particularly limited, but preferably, a copper halide salt and a phosphate-based heat stabilizer can be used in combination, and more preferably, an iodine copper salt and a phosphate-based heat stabilizer can be used.

In 100 parts by weight of the resin composition of the present invention, mixing of the heat stabilizer is included in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, even more preferably 0.1 to 2 parts by weight or 0.1 to It may be included in an amount of 1 part by weight. When the content of the heat stabilizer in 100 parts by weight of the resin composition is less than 0.1 parts by weight, the effect of improving the heat resistance and weathering properties according to the addition of the heat stabilizer may be negligible. Conversely, when the content of the heat stabilizer exceeds 5 parts by weight, mechanical properties and Machinability may deteriorate.

The lower limit of the heat stabilizer content may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, or 2.5 parts by weight or more, and an upper limit of 5 parts by weight or less , 4.5 parts by weight or less, 4 parts by weight or less, 3.5 parts by weight or less, 3 parts by weight or less, or 2.5 parts by weight or less.

(E) other optional additional ingredients

To the resin composition of the present invention, other additives may be added as necessary within the range capable of achieving the object of the present invention in addition to the above-described components.

The types of other additives are not particularly limited, and additives commonly used in thermoplastic resin compositions may be used without limitation, for example, additives selected from the group consisting of compatibilizers, antioxidants, lubricants, or mixtures thereof. One or more can be used.

The content of the other additives is not particularly limited, and may be used within 0.1 to 15 parts by weight based on 100 parts by weight of the resin composition of the present invention according to the purpose of use and use.

The pellet length prepared from the resin composition of the present invention includes 5 mm to 30 mm, and more preferably 6 mm to 18 mm. The length of the pellet can be adjusted according to the speed of the cutter after drawing, and when the length of the resin composition pellet is less than 5 mm, the fiber length is shortened to slightly increase the mechanical strength, but the thermal and electrical conductivity and electromagnetic wave shielding properties are reduced, When the length of the pellet is longer than 20 mm, thermal and electrical conductivity and electromagnetic shielding properties increase, but mechanical strength may decrease.

Since the thermally conductive thermoplastic resin composition of the present invention obtained as described above exhibits remarkably high thermal conductivity, excellent mechanical strength, and pressure/injection moldability at the same time, molded articles exhibiting remarkably excellent heat dissipation properties when subjected to pressure/injection processing, such as automobiles , Electrical products, electronic products, molded products for LED lighting (eg housing, heat sink) can be obtained.

Hereinafter, the present invention will be described in more detail through Examples and Comparative Examples. However, these examples are only for the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[ Example And Comparative example ]

The components used in the examples and comparative examples are specifically as follows.

(A) Thermoplastic resin

(A-1) Polyamide

(A-1-1) Polyamide 6 with a number average molecular weight of 11,500

(A-1-2) Polyamide 6 with a number average molecular weight of 30,000

(A-2) Polycarbonate

(A-2-1) Polycarbonate resin having a number average molecular weight of 17,000

(A-2-2) Polycarbonate resin having a number average molecular weight of 22,000

(A-3) Polyester

(A-3-1) Polyethylene terephthalate having a number average molecular weight of 20,000

(A-3-2) Polyethylene terephthalate having a number average molecular weight of 26,000

(B) Graphene Oxide : particle size 6㎛, thermal conductivity 5000W/m·k

(C-1) Carbon long fiber : As the carbon long fiber (C-1), a diameter of 6 µm, focused with urethane resin, and a PAN-based carbon long fiber tow having a filament number of 12,000 were used.

(C-2) Glass long fiber : As the glass long fiber (C-2), a glass long fiber tow having a filament number 2,000, having a diameter of 12 μm, focused with an epoxy resin, and surface-treated with silane was used.

(C-3) Short carbon fiber : As the short carbon fiber (C-3), a diameter of 6 µm and a length of 6 mm were used, and a PAN-based carbon carbon fiber having a filament number of 12,000 was used and focused with urethane resin.

(C-4) Short glass fiber: As the short glass fiber (F-4), a diameter of 12 μm and a length of 4 mm were used, and a short glass fiber having a filament number of 3,500, which was surface-treated with silane, was used.

(D) Heat stabilizer : CuI (Incasa Co.) (Cuprous Iodide), KI (Incasa Co.) (Potassium Iodide), and disodium pyrophosphate were used in a 1: 1 ratio.

Based on the composition, the short fiber-reinforced composition was tested by extrusion processing, and the long-fiber reinforced composition was tested by preparing a long-fiber reinforced composition pellet through a drawing process after extrusion.

bracket Example 1 to 6, Comparative example 1 to 5 and Comparative example 8 to 10: Long fibers Reinforced thermoplastic resin composition Pellet Produce

Among the components and contents shown in Tables 1, 4, and 7, components excluding carbon long fibers (C-1) and glass long fibers (C-2) were mixed and extruded to prepare a master batch of a thermoplastic resin composition.

The prepared thermoplastic resin composition masterbatch was introduced into a resin injection portion of a pultrusion device.

The long carbon fiber (C-1) and glass long fiber (C-2) in the form of a lobe are impregnated through the process of pulling and squeezing the thermoplastic resin composition into the long fiber while passing through the dies of the pultrusion machine, respectively. The strands in a continuous state were pultrusion-cooled and cut into pellets having a length of 30 mm to prepare long fiber-reinforced thermoplastic resin pellets.

bracket Comparative example 6 and 7: Short fiber Reinforced thermoplastic resin composition Pellet Produce

In Tables 1, 4 and 7, the components and contents of Comparative Examples 6 and 7, L/D=48, Φ=25 in a twin-screw melt kneading extruder, melt temperature 230 to 250 ^o C, screw rotation speed of 150 rpm, about- Extruded under conditions of a first vent pressure of 600 mmHg and a self-feed rate of 20 kg/h. After the extruded strand was cooled in water, it was cut with a rotary cutting machine to prepare a short fiber-reinforced thermoplastic resin composition pellet.

<Measurement of physical properties>

(1) Heat-resistant tensile strength change rate (ΔTS): ASTM D638 standard, 140 ℃, 1000 hours

(2) Thermal Conductivity In(In-Plane)/Through-Plane:

Based on ASTM E1461 (Laser flash method), specimen length 10x10mm, thickness: 2mm

(3) Electromagnetic shielding (dB): ASTM D4935

(4) Weatherability (ΔE): ΔE(L,a,b) = (ΔL) ² + (Δa) ² + (Δb) ^{2 in the} concept of L, a, and b color differences, which numerically expresses the perceptual difference between ^two perceptors , External test request (Korea Institute for Construction and Living Environment Testing, based on a survey amount of 2500 KJ/m2)

(5) Extrusion processability: Relative comparison based on the following criteria depending on the degree of strand break during extrusion

-◎: No break-○: Break less than 30%

-△: Break less than 70%-X: Extrusion impossible

Claims (8)

Based on 100 parts by weight of the total resin composition,
(A) 50 to 90 parts by weight of a thermoplastic resin,
(B) 0.05 to 1 part by weight of graphene oxide,
(C) 10 to 48 parts by weight of carbon long fibers and
(D) 0.1 to 5 parts by weight of a heat stabilizer,
Long fiber reinforced thermoplastic resin composition. The long fiber-reinforced thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is polyamide having a number average molecular weight of 17,000 or less, polycarbonate having a number average molecular weight of 20,000 or less, polyester having a number average molecular weight of 23,000 or less, or a mixture thereof. The long fiber-reinforced thermoplastic resin composition according to claim 1, wherein the (B) graphene oxide has a particle diameter of 1 to 10 μm and a thermal conductivity of 4500 to 5500 W/m·k. The long fiber-reinforced thermoplastic resin composition of claim 1, wherein the carbon long fiber (C) is surface-treated with a silane-based or titanate-based polymer. The long fiber-reinforced thermoplastic resin composition according to claim 1, wherein the heat stabilizer (D) comprises a phosphate-based heat stabilizer and a halogenated copper salt. The method of claim 1, wherein the resin composition is prepared in a pellet form, (C) carbon long fibers are arranged parallel to the longitudinal direction of the pellets, (E) the length of the carbon long fibers and the length of the pellets 5 to 30mm The same thing, long fiber-reinforced thermoplastic resin composition. The composition of claim 1, further comprising an additive selected from the group consisting of compatibilizers, antioxidants, lubricants, or mixtures thereof. A molded article comprising the long fiber-reinforced thermoplastic resin composition according to any one of claims 1 to 7.