JP6792376B2 - Polyester resin composition and molded product - Google Patents

Description

The present invention relates to a polyester resin composition and a molded product. Specifically, the present invention is excellent in flame retardancy, has less mold corrosion during molding, and can be used for a long time in close proximity to a metal part. The present invention relates to a polyester resin composition which is less likely to corrode and has excellent melt thermal stability and a molded product thereof.

Thermoplastic polyester resins typified by polybutylene terephthalate and polyethylene terephthalate are excellent in mechanical strength, chemical resistance, electrical insulation, etc., and also have excellent heat resistance, moldability, and recyclability. Therefore, it is widely used for electrical and electronic equipment parts, automobile parts and other electrical parts, mechanical parts, and the like.

Electrical and electronic equipment parts, etc. are required to have a high degree of flame retardancy with thin walls due to the remarkable progress of miniaturization and thinning of parts in recent years, and achieve the vertical combustion rank V-0 specified by UL-94. Is required. A flame retardant is added to make the thermoplastic resin flame retardant.

According to Patent Document 1, the applicant has stated in Patent Document 1 that a thermoplastic polyester resin contains a specific amount of a brominated flame retardant, the amount of free bromine is a specific amount or less, and the yellow index of the resin composition is 23 or less. The invention of the resin composition was proposed. In the present invention, as the brominated flame retardant, specifically, brominated benzyl poly (meth) acrylate such as pentabromobenzyl polyacrylate, brominated epoxy compound, brominated polystyrene, and brominated imide compound are preferable, and bromide is particularly preferable. It is disclosed that polystyrene is preferable (see Patent Document 1, paragraph [0022]).

However, when a brominated polyacrylate-based flame retardant, which is a preferred flame retardant, is mixed with the thermoplastic polyester resin and compounded, the thermoplastic polyester resin may be decomposed or the melt thermal stability is poor. It was found that it was easy to become. It has also been found that corrosive gas is generated during molding due to exposure to high temperature during molding, which causes problems such as mold contamination and poor surface appearance of the molded product.
Furthermore, in many cases, metal parts such as terminals are used in close proximity to electrical components, and a problem has been found in which nearby metal parts are corroded by long-term use.

Further, the equipment parts are usually printed to clearly indicate the manufacturing company name, brand name, product number, manufacturing lot number, etc., but recently, laser marking having a high printing speed is often used. In particular, clearer printing characteristics are required due to miniaturization of parts, and excellent laser printability is also required from the viewpoint of improving productivity by improving printing speed.
Therefore, when a brominated polyacrylate-based flame retardant is applied to a thermoplastic polyester resin, it is excellent not only in flame retardancy but also in melt heat stability, a small amount of gas generated during molding, and excellent laser printability. Is required.

Japanese Unexamined Patent Publication No. 2013-57009

An object (problem) of the present invention is to have excellent flame retardancy, less mold corrosion during molding, less corrosion of metal parts even when used in close proximity to metal parts for a long time, and heat stability of melting. It is also an object of the present invention to provide an excellent polyester resin composition.

As a result of diligent studies to solve the above problems, the present inventors have narrow molecular weights such that the ratio of mass average molecular weight (Mw) to number average molecular weight (Mn) is less than a specific value as a brominated polyacrylate flame retardant. We have found that those having a distribution solve the above-mentioned problems, and have completed the present invention.
The present invention relates to the following polyester resin compositions and molded articles.

[1] A resin composition containing 3 to 60 parts by mass of a brominated polyacrylate-based flame retardant (B) with respect to 100 parts by mass of the thermoplastic polyester resin (A), wherein the brominated polyacrylate-based flame retardant (B) is contained. ), The ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) is 5.5 or less, which is a polyester resin composition.
[2] The polyester-based resin composition according to the above [1], wherein the Na element concentration measured by the fluorescent X-ray analysis method of the brominated polyacrylate-based flame retardant (B) is 500 ppm or less.
[3] The polyester-based resin composition according to the above [1] or [2], wherein the mass average molecular weight (Mw) of the brominated polyacrylate-based flame retardant (B) measured by GPC is 10,000 or more.
[4] The polyester-based resin composition according to any one of the above [1] to [3], wherein the bromide polyacrylate-based flame retardant (B) is pentabromobenzyl polyacrylate.
[5] A molded product comprising the polyester-based resin composition according to any one of the above [1] to [4].

The polyester-based resin composition of the present invention has excellent flame retardancy, less mold corrosion during molding, less corrosion of metal parts even when used in close proximity to metal parts for a long time, and melt thermal stability. It is also excellent in laser printability.

FIG. 1 is a GPC chart of the pentabromobenzyl polyacrylate used in Examples and Comparative Examples.

The polyester-based resin composition of the present invention is a resin composition containing 3 to 60 parts by mass of a brominated polyacrylate-based flame retardant (B) with respect to 100 parts by mass of the thermoplastic polyester resin (A), and is brominated. Brominated Polyacrylate Flame Retardant (B) The ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC of the polyacrylate flame retardant (B) is 5.5 or less. It is characterized by being.

Hereinafter, the contents of the present invention will be described in detail.
The description of each constituent requirement described below may be based on typical embodiments and specific examples of the present invention, but the present invention is construed as being limited to such embodiments and specific examples. It's not a thing. In the specification of the present application, "~" is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value, and "ppm" means mass ppm.

[Thermoplastic polyester resin (A)]
The thermoplastic polyester resin (A), which is the main component of the resin composition of the present invention, is a polyester obtained by polycondensation of a dicarboxylic acid compound and a dihydroxy compound, polycondensation of an oxycarboxylic acid compound, or polycondensation of these compounds. It may be either homopolyester or copolyester.

As the dicarboxylic acid compound constituting the thermoplastic polyester resin (A), an aromatic dicarboxylic acid or an ester-forming derivative thereof is preferably used.
Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, Biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulphon-4,4'-dicarboxylic acid , Diphenylisopropyridene-4,4'-dicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid, anthracene-2,5-dicarboxylic acid, anthracene-2,6-dicarboxylic acid, p Examples thereof include −terphenylene-4,4′-dicarboxylic acid and pyridine-2,5-dicarboxylic acid, and terephthalic acid can be preferably used.

Two or more kinds of these aromatic dicarboxylic acids may be mixed and used. As is well known, dimethyl ester or the like can be used as an ester-forming derivative in the polycondensation reaction in addition to the free acid.
In addition, in a small amount, along with these aromatic dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, dodecandioic acid and sebacic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and 1 , 4-Cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids can be mixed and used.

Examples of the dihydroxy compound constituting the thermoplastic polyester resin (A) include ethylene glycol, propylene glycol, butanediol, hexylene glycol, neopentyl glycol, 2-methylpropane-1,3-diol, diethylene glycol and triethylene glycol. Examples thereof include aliphatic diols, alicyclic diols such as cyclohexane-1,4-dimethanol, and mixtures thereof. If the amount is small, one or more long-chain diols having a molecular weight of 400 to 6,000, that is, polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, or the like may be copolymerized.
In addition, aromatic diols such as hydroquinone, resorcin, naphthalene diol, dihydroxydiphenyl ether, and 2,2-bis (4-hydroxyphenyl) propane can also be used.

In addition to the bifunctional monomers as described above, trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane for introducing a branched structure, and fatty acids for adjusting the molecular weight, etc. A small amount of the monofunctional compound can also be used in combination.

As the thermoplastic polyester resin (A), a resin mainly composed of a polycondensation of a dicarboxylic acid and a diol, that is, a resin in which 50% by mass, preferably 70% by mass or more of the total resin is composed of this polycondensate is used. The dicarboxylic acid is preferably an aromatic carboxylic acid, and the diol is preferably an aliphatic diol.

Of these, polyalkylene terephthalate in which 95 mol% or more of the acid component is terephthalic acid and 95% by mass or more of the alcohol component is an aliphatic diol is preferable. Typical examples are polybutylene terephthalate and polyethylene terephthalate. It is preferable that these are close to homopolyester, that is, 95% by mass or more of the total resin is composed of a terephthalic acid component and a 1,4-butanediol or ethylene glycol component.

The intrinsic viscosity of the thermoplastic polyester resin (A) is preferably 0.3 to 2 dl / g. If an intrinsic viscosity of less than 0.3 dl / g is used, the obtained resin composition tends to have low mechanical strength. If the value is higher than 2 dl / g, the fluidity of the resin composition may be deteriorated and the moldability may be deteriorated. The intrinsic viscosity is more preferably 0.4 dl / g or more, further 0.5 dl / g or more, particularly 0.6 dl / g or more, and more preferably 0.4 dl / g or more from the viewpoint of moldability and mechanical properties. Is 1.5 dl / g or less, more preferably 1.3 dl / g or less, and particularly preferably 1.2 dl / g or less.
The intrinsic viscosity of the thermoplastic polyester resin (A) is a value measured at 30 ° C. in a 1: 1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

The amount of the terminal carboxyl group of the thermoplastic polyester resin (A) may be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and 30 eq / ton or less. Is even more preferable. If it exceeds 50 eq / ton, gas is likely to be generated during melt molding of the resin composition. The lower limit of the amount of the terminal carboxyl group is not particularly defined, but is usually 3 eq / ton, preferably 5 eq / ton, and more preferably 10 eq / ton.

The amount of terminal carboxyl groups of the thermoplastic polyester resin (A) is a value measured by titration using a 0.01 mol / l benzyl alcohol solution of sodium hydroxide in which 0.5 g of the resin is dissolved in 25 ml of benzyl alcohol. is there.
As a method for adjusting the amount of the terminal carboxyl group, a conventionally known arbitrary method such as a method of adjusting the polymerization conditions such as the raw material charging ratio at the time of polymerization, the polymerization temperature, the depressurization method, and the method of reacting the terminal blocking agent can be used. Just do it.

Among them, the thermoplastic polyester resin (A) preferably contains a polybutylene terephthalate resin, and 50% by mass or more of the thermoplastic polyester resin (A) is preferably a polybutylene terephthalate resin.

Polybutylene terephthalate resin is produced by melt-polymerizing a dicarboxylic acid component containing terephthalic acid as a main component or an ester derivative thereof and a diol component containing 1,4-butanediol as a main component by a batch method or a continuous method. can do. Further, the degree of polymerization (or molecular weight) can be increased to a desired value by producing a low molecular weight polybutylene telecturate resin by melt polymerization and then performing solid phase polymerization under a nitrogen stream or under reduced pressure.

The polybutylene terephthalate resin preferably has a production method in which a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component are continuously melt-polycondensed.

The catalyst used in carrying out the esterification reaction may be a conventionally known catalyst, and examples thereof include titanium compounds, tin compounds, magnesium compounds, and calcium compounds. Of these, a titanium compound is particularly suitable. Specific examples of the titanium compound as an esterification catalyst include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

The polybutylene terephthalate resin may be a polybutylene terephthalate resin modified by copolymerization (hereinafter, may also be referred to as “modified polybutylene terephthalate resin”), and a specific preferable copolymer thereof is poly. Examples thereof include polyester ether resin copolymerized with alkylene glycols (particularly polytetramethylene glycol), dimer acid copolymer polybutylene terephthalate resin, and isophthalic acid copolymer polybutylene terephthalate resin.

When a polyester ether resin copolymerized with polytetramethylene glycol is used as the modified polybutylene terephthalate resin, the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass, preferably 5 to 30% by mass. % Is more preferable, and 10 to 25% by mass is further preferable.
When a dimer acid copolymer polybutylene terephthalate resin is used as the modified polybutylene terephthalate resin, the ratio of the dimer acid component to the total carboxylic acid component is preferably 0.5 to 30 mol% as the carboxylic acid group. 1 to 20 mol% is more preferable, and 3 to 15 mol% is further preferable.
When an isophthalic acid copolymer polybutylene terephthalate resin is used as the modified polybutylene terephthalate resin, the ratio of the isophthalic acid component to the total carboxylic acid components is preferably 1 to 30 mol% as the carboxylic acid group, and 1 to 1 20 mol% is more preferable, and 3 to 15 mol% is even more preferable.
Among the modified polybutylene terephthalate resins, polyester ether resin copolymerized with polytetramethylene glycol and isophthalic acid copolymerized polybutylene terephthalate resin are preferable.

The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dl / g. From the viewpoint of moldability and mechanical properties, those having an intrinsic viscosity in the range of 0.6 to 1.5 dl / g are more preferable. If an intrinsic viscosity of less than 0.5 dl / g is used, the obtained resin composition tends to have low mechanical strength. If the value is higher than 2 dl / g, the fluidity of the resin composition may be deteriorated and the moldability may be deteriorated.

The amount of the terminal carboxyl group of the polybutylene terephthalate resin may be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 40 eq / ton or less. , 30 eq / ton or less, more preferably. If it exceeds 50 eq / ton, gas is likely to be generated during melt molding of the resin composition. The lower limit of the amount of the terminal carboxyl group is not particularly determined, but is usually 10 eq / ton in consideration of the productivity of producing the polybutylene terephthalate resin.

The amount of terminal carboxyl groups in the polybutylene terephthalate resin is a value measured by titration using a 0.01 mol / l benzyl alcohol solution of sodium hydroxide in which 0.5 g of the polyalkylene terephthalate resin is dissolved in 25 mL of benzyl alcohol. is there. As a method for adjusting the amount of the terminal carboxyl group, a conventionally known arbitrary method such as a method of adjusting the polymerization conditions such as the raw material charging ratio at the time of polymerization, the polymerization temperature, the depressurization method, and the method of reacting the terminal blocking agent can be used. Just do it.

As the thermoplastic polyester resin (A), those containing a polybutylene terephthalate homopolymer and the modified polybutylene terephthalate resin are also preferable. By containing a specific amount of the modified polybutylene terephthalate resin, the weld strength is likely to be improved, which is preferable.
When the polybutylene terephthalate homopolymer and the modified polybutylene terephthalate resin are contained, the content of the modified polybutylene terephthalate resin is preferably 100% by mass based on the total of 100% by mass of the polybutylene terephthalate homopolymer and the modified polybutylene terephthalate resin. It is 5 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 30% by mass.

Further, the thermoplastic polyester resin (A) preferably contains a polybutylene terephthalate resin and a polyethylene terephthalate resin.
When the polybutylene terephthalate resin and the polyethylene terephthalate resin are contained, the content of the polyethylene terephthalate resin is preferably 5 to 50% by mass with respect to 100% by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin. It is more preferably 10 to 45% by mass, and even more preferably 15 to 40% by mass.

The polyethylene terephthalate resin is a resin whose main constituent unit is an oxyethylene oxyterephthaloyl unit composed of terephthalic acid and ethylene glycol with respect to all constituent repeating units, and contains a constituent repeating unit other than the oxyethylene oxyterephthaloyl unit. May be good. The polyethylene terephthalate resin is produced by using terephthalic acid or a lower alkyl ester thereof and ethylene glycol as a main raw material, but other acid components and / or other glycol components may be used together as a raw material.

Acid components other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-. Examples thereof include phenylenedioxydiacetic acid and structural isomers thereof, dicarboxylic acids such as malonic acid, succinic acid and adipic acid and derivatives thereof, and oxyacids such as p-hydroxybenzoic acid and glycolic acid or derivatives thereof.

Examples of the diol component other than ethylene glycol include aliphatic glycols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol, and neopentyl glycol, and cyclohexane. Examples thereof include alicyclic glycols such as dimethanol, aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S, and the like.

Further, the polyethylene terephthalate resin is a branched component, such as a trifunctional acid such as tricarbaryl acid, trimeric acid, trimellitic acid or the like, or a tetrafunctional acid such as pyromellitic acid, or an acid having glycerin, trimethyl propane, etc. Copolymerized with 1.0 mol% or less, preferably 0.5 mol% or less, more preferably 0.3 mol% or less of an alcohol having a trifunctional or tetrafunctional ester-forming ability such as pentaerythrit. It may be.

The intrinsic viscosity of the polyethylene terephthalate resin is preferably 0.3 to 1.5 dl / g, more preferably 0.3 to 1.2 dl / g, and particularly preferably 0.4 to 0.8 dl / g.

The concentration of the terminal carboxyl group of the polyethylene terephthalate resin is preferably 3 to 50 eq / ton, particularly preferably 5 to 40 eq / ton, more preferably 10 to 30 eq / ton.
The terminal carboxyl group concentration of the polyethylene terephthalate resin is a value obtained by dissolving 0.5 g of the polyethylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol / l benzyl alcohol solution of sodium hydroxide. is there.
As a method for adjusting the amount of the terminal carboxyl group, a conventionally known arbitrary method such as a method of adjusting the polymerization conditions such as the raw material charging ratio at the time of polymerization, the polymerization temperature, the depressurization method, and the method of reacting the terminal blocking agent can be used. Just do it.

[Brominated polyacrylate flame retardant (B)]
The polyester-based resin composition of the present invention contains a brominated polyacrylate-based flame retardant (B) as a flame retardant. As the brominated polyacrylate-based flame retardant (B), an acrylate monomer containing a bromine atom, particularly a benzyl (meth) acrylate, is polymerized alone, two or more kinds are copolymerized, or another vinyl-based monomer is copolymerized. It is preferable that the polymer obtained by the above is added, and the bromine atom is added to the benzene ring, and the number of additions is preferably 1 to 5 per benzene ring, particularly 4 to 5 added. ..

Examples of the benzyl acrylate containing a bromine atom include pentabromobenzyl acrylate, tetrabromobenzyl acrylate, tribromobenzyl acrylate, and a mixture thereof. Moreover, as a benzyl methacrylate containing a bromine atom, a methacrylate corresponding to the above-mentioned acrylate can be mentioned.

Other vinyl-based monomers used for copolymerizing with benzyl (meth) acrylate containing a bromine atom include, for example, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and benzyl acrylate. Acrylate esters; Methacrylic acid and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and benzyl methacrylate; unsaturated carboxylic acids such as styrene, acrylonitrile, fumaric acid and maleic acid or anhydrides thereof; Examples thereof include vinyl acetate and vinyl chloride.

The other vinyl-based monomer used for the copolymerization is usually preferably used in an equimolar amount or less, particularly 0.5 times the molar amount or less, with respect to the benzyl (meth) acrylate containing a bromine atom.

Further, as the other vinyl-based monomer, xylenediacrylate, xylenedimethacrylate, tetrabromoxylenediacrylate, tetrabromoxylenedimethacrylate, butadiene, isoprene, divinylbenzene and the like can also be used, and these are usually bromine atoms. 0.5 times the molar amount or less can be used with respect to benzyl acrylate or benzyl methacrylate containing.

As the brominated polyacrylate-based flame retardant (B), pentabromobenzyl polyacrylate is preferable because it has a high bromine content and is excellent in electrical insulation characteristics (tracking resistance characteristics).

In the present invention, the ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) as the brominated polyacrylate flame retardant (B) is 5. Use one that is 5 or less. By using a material having Mw / Mn of 5.5 or less, it is excellent in flame retardancy, the amount of gas generated during molding is small, mold contamination is reduced, and the heat stability of fusion and laser printability are also excellent. It has been found to be a resin composition. The reason is that, although it has not been fully elucidated yet, the narrow molecular weight distribution of Mw / Mn of 5.5 or less means that there are few low molecular weight components that are likely to cause gas generation. Conceivable. Mw / Mn is preferably 5.0 or less, more preferably 4.5 or less, and preferably 3.0 or more.

Further, the molecular weight distribution of the brominated polyacrylate-based flame retardant (B) is preferably a single peak. FIG. 1 is a GPC chart of the pentabromobenzyl polyacrylate used in Examples and Comparative Examples, but its molecular weight distribution curve is a single peak like B-1 and B-2 used in Examples described later. Those showing a double peak distribution (double peak) such as BX used as a comparative example are preferable. Further, it is preferable that the molecular weight distribution of the brominated polyacrylate flame retardant (B) is a single peak, and the maximum peak position thereof is in the range of the molecular weight of 20,000 to 50,000.

Further, the mass average molecular weight (Mw) of the brominated polyacrylate flame retardant (B) is preferably larger because less corrosive gas is generated. Specifically, 10,000 or more is preferable, 15,000 or more is more preferable, and 20,000 or more is further preferable.
There is no upper limit to the mass average molecular weight (Mw), but if it is too large, it is considered that melt dispersion cannot be sufficiently performed. Therefore, it is preferably small to some extent, specifically 200,000 or less, and 100,000 or less. If it is, it is more preferable, and if it is 50,000 or less, it is further preferable.
The idea of the number average molecular weight (Mn) is also preferable because it is considered that the larger the mass average molecular weight (Mw), the smaller the amount of corrosive gas generated. Specifically, 3,000 or more is preferable, 4,500 or more is more preferable, and 6,000 or more is further preferable.
There is no upper limit to the number average molecular weight (Mn), but if it is too large like the mass average molecular weight (Mw), it is considered that melt dispersion cannot be sufficiently performed. Therefore, it is preferable that the number average molecular weight (Mn) is small to some extent. It is preferably 000 or less, more preferably 20,000 or less, and even more preferably 10,000 or less.

The molecular weight distribution Mw / Mn of the brominated polyacrylate-based flame retardant (B) can be adjusted to 5.5 or less, more preferably to a single peak, by various known methods, but the raw material brominated acrylate A method of adjusting the stirring speed when a monomer is polymerized with a polymerization initiator such as dicumyl peroxide, a method of anionic polymerization using an alkyllithium polymerization initiator, or a method of polymerizing a greeninal reagent such as alkylmagnesium bromide. Examples thereof include a method of polymerization as an initiator.
Further, it is also possible to appropriately select and use a commercially available product that satisfies the conditions specified in the present invention.

Further, the brominated polyacrylate-based flame retardant (B) preferably has a Na element concentration of 500 ppm or less as measured by a fluorescent X-ray analysis method. If the Na element concentration exceeds 500 ppm, the melt heat stability of the resin becomes poor during the production of the polyester composition, and the viscosity retention tends to decrease.
The Na element concentration in the brominated polyacrylate-based flame retardant (B) is measured by a fluorescent X-ray analysis method. If the Na element concentration is low and it is not detected by the fluorescent X-ray analysis method, the ICP emission spectroscopic analysis method, which is an emission spectroscopic analysis method using high frequency inductively coupled plasma (ICP) as a light source, is used again. Make a measurement.

The brominated polyacrylate-based flame retardant (B) having an Na element concentration of 500 ppm or less can be preferably produced by washing the brominated polyacrylate-based flame retardant with warm water at 40 to 100 ° C.

As an example of the method for producing the brominated polyacrylate-based flame retardant (B) used in the present invention, using pentabromobenzyl polyacrylate (hereinafter, also referred to as PBBPA) as an example of the brominated flame retardant, it is used in the present invention. PBBPA is preferably produced by a method consisting of the following steps 1 to 4.
Step 1: C ₆ H _5- CH ₃ + Br ₂ → C ₆ Br _5- CH ₃
Step 2: C ₆ H _5- CH ₃ + Br ₂ → C ₆ Br _5- CH ₂ Br
Step 3: C ₆ Br _5- CH ₂ Br + CH ₂ = CH-COOH
→ CH ₂ = CH-COOCH _2- C ₆ Br ₅
Step 4: CH ₂ = CH-COOCH _2- C ₆ Br ₅ → Polymerization → PBBPA
According to this production method, PBBPA having a high bromine concentration can be obtained in a high yield. Then, the obtained PBBPA is washed with water. In step 3, HBr, NaOH, anhydrous Na carbonate and the like are added, and Na tends to remain in the obtained PBBPA.
Water washing is preferably carried out with warm water having a temperature of 40 to 100 ° C., and after washing with water, PBBPA having an Na element concentration of 500 ppm or less can be obtained by drying. Methanol washing instead of water washing is not preferable because it is difficult to adjust the Na element concentration in the above range. The temperature of hot water for washing with water is preferably 60 to 100 ° C, more preferably 85 to 100 ° C.
Further, it is preferable that the Na element concentration can be further lowered by lengthening or repeating the water washing time.

Further, the brominated polyacrylate-based flame retardant (B) has a Mg ion concentration of 5 to 2000 ppm measured by ICP emission spectroscopic analysis, which is an emission spectroscopic analysis method using high frequency inductively coupled plasma (ICP) as a light source. preferable. Further, the Al ion concentration is preferably 5 to 3000 ppm. When the Mg ion concentration is in such a range, the retention heat stability of the PBT resin composition becomes good. Further, when the Al ion concentration is in the above range, it becomes good from the viewpoint of molding processability.

The content of the brominated polyacrylate-based flame retardant (B) is 3 to 60 parts by mass, preferably 5 parts by mass or more, and more preferably 8 parts by mass or more with respect to 100 parts by mass of the thermoplastic polyester resin (A). Further, it is preferably 10 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less. If the content is less than 3 parts by mass, the flame retardancy tends to decrease and the laser printability deteriorates. On the contrary, if it exceeds 60 parts by mass, a large amount of gas is generated, which causes contamination of the mold and contact contamination of the molded product, and it becomes unnecessary to stabilize the heat of fusion of the resin during the production of the polyester composition, resulting in a decrease in viscosity retention. It ends up.

[Antimony compound]
The resin composition of the present invention preferably contains an antimony compound which is a flame retardant aid.
Examples of the antimony compound include antimony trioxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), sodium antimonate and the like. In particular, antimony trioxide is preferable.
The content of the antimony compound is preferably 0.5 to 20 parts by mass, more preferably 0.7 to 18 parts by mass, and further preferably 1 to 15 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). It is by mass, particularly 2 to 13 parts by mass, most preferably 3 to 10 parts by mass.

The mass concentration of the bromine atom derived from the brominated polyacrylate flame retardant (B) and the antimony atom derived from the antimony compound in the resin composition of the present invention is usually 3 to 25% by mass in total, and 4 to 4 to It is preferably 22% by mass, more preferably 5 to 16% by mass, and even more preferably 6 to 15% by mass. If it is less than 3% by mass, the flame retardancy tends to decrease, and if it exceeds 25% by mass, the mechanical strength and tracking resistance characteristics may decrease. The mass ratio (Br / Sb) of the bromine atom and the antimony atom is preferably 0.3 to 5, and more preferably 0.3 to 4.

[Boric acid metal salt]
The resin composition of the present invention preferably contains a metal boric acid salt, and the content thereof is preferably 0.3 to 10 parts by mass with respect to 100 parts by mass (A) of the thermoplastic polyester resin. Further, it is preferable that the mass ratio (i / ii) of the contents of (i) antimony trioxide and (ii) boric acid metal salt is in the range of 1 to 20. By containing the boric acid metal salt in such an amount and mass ratio, it is possible to improve the feedability at the time of melt-kneading, the dispersibility of the resin composition, and the combustibility, and it is also excellent in laser printability. The (i) / (ii) ratio is preferably 2 to 18, more preferably 4 to 16.

As the boric acid forming the boric acid metal salt, non-condensed boric acid such as orthoboric acid and metaboric acid; condensed boric acid such as pyroboric acid, tetraboric acid, pentaboric acid and octaboric acid; and basic boric acid are preferable. The metal forming the salt with these may be an alkali metal, but among them, a polyvalent metal such as an alkaline earth metal, a transition metal, or a metal of Group 2B of the periodic table is preferable. Further, the boric acid metal salt is preferably a hydrate.

Examples of the metal borate salt include a non-condensable metal borate salt, a condensed metal borate salt, and a basic metal borate borate salt. Examples of the non-condensable metal borate salt are alkaline earth metal borates such as calcium orthoborate and calcium metaborate. Transition metal borates such as manganese orthoborate and copper metaborate; and borates of group B metals of the periodic table such as zinc metaborate and cadmium metaborate. Of these, metaborate is preferred.

Condensed metal borates include alkaline earth metal borates such as trimagnesium tetraborate and calcium pyroborate; transition metal borates such as manganese tetraborate and nickel diborate; periodic tables such as zinc tetraborate and cadmium tetraborate. Examples thereof include borate of Group 2B metal.
Examples of the basic borate metal salt include basic borates of Group B metals of the periodic table such as zinc basic borate and cadmium basic borate. Further, a hydrogen borate salt corresponding to these borates (for example, manganese hydrogen borate ortho) can also be used.

As the metal borate salt used in the present invention, it is preferable to use an alkaline earth metal or a salt of a metal of Group 2B of the Periodic Table 2B, for example, zinc borate or calcium borate. The zinc borate compounds, such as zinc borate (2ZnO · _3B 2 _{O 3)} and zinc borate · 3.5 hydrate _{(2ZnO · 3B 2 O 3 ·} 3.5H 2 O) is contained, the calcium borate compound calcium borate anhydride (2CaO · _3B 2 _{O 3)} and the like. The calcium borate compound, colemanite (a mainly inorganic compound consisting of calcium borate, usually, hydrates of formula _{2CaO · 3B 2 O 3 · 5H} 2 O) may be used.
Among these zinc borates and calcium borates, hydrates are preferable. In addition, zinc borate is preferable.

Among the above, the borate metal salt preferably has an alkali metal and / or alkaline earth metal content of 2,000 mass ppm or less in the borate metal salt from the viewpoint of retention heat stability. Examples of the alkali metal and alkaline earth metal include K, Na, Ca, Mg and the like, and among these, those having a K and / or Ca content of 2,000 mass ppm or less are preferable. More preferably 1,500 mass ppm or less, still more preferably 1,000 mass ppm or less, and particularly preferably 800 mass ppm or less.
The content of alkali metal and / or alkaline earth metal in the metal borate salt can be measured by fluorescent X-ray analysis.

Further, the boric acid metal salt used for producing the polybutylene terephthalate resin composition preferably has an average particle diameter of 4 μm or more, more preferably 6 μm or more, and further preferably 8 μm or more. The upper limit of the average particle size is preferably 30 μm, more preferably 20 μm, and even more preferably 15 μm. When the average particle size of the boric acid metal salt is less than 4 μm, the feedability at the time of melt-kneading tends to deteriorate, the dispersed state of the obtained resin composition tends to deteriorate, and the combustibility tends to deteriorate. Absent. On the other hand, if the average particle size exceeds 30 μm, the mechanical properties may be deteriorated and the surface appearance may be significantly impaired, which is not preferable. The average particle size of the boric acid metal salt refers to the median diameter (D50) measured by a laser diffraction method.

Further, as the boric acid metal salt, one that has been surface-treated with a surface-treating agent such as a silane coupling agent may be used. As the surface treatment agent, any conventionally known surface treatment agent can be used, and specific examples thereof include surface treatment agents such as aminosilane type, epoxysilane type, allylsilane type and vinylsilane type as the silane coupling agent.

Among these, an aminosilane-based surface treatment agent is preferable. Specific examples of the aminosilane-based coupling agent include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ- (2-aminoethyl) aminopropyltrimethoxysilane. ..

As the surface treatment agent for the metal boric acid salt, other components, specifically, for example, epoxy resin and urethane resin, can be added to the surface treatment agent such as the silane coupling agent as long as the effects of the present invention are not impaired. It may contain an acrylic resin, an antistatic agent, a lubricant, a water repellent, and the like.

As a surface treatment method using such a surface treatment agent, the surface treatment may be performed in advance with the surface treatment agent, or when the resin composition of the present invention is prepared, the surface treatment is performed separately from the untreated boric acid metal salt. The surface can be treated by adding an agent.

As described above, the content of the boric acid metal salt is preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, but more preferably 0.5 parts by mass or more. It is more preferably 7 parts by mass or less, and further preferably 5 parts by mass or less.

[Stabilizer]
The resin composition of the present invention preferably contains a stabilizer, and the stabilizer is preferably a phenolic stabilizer.

As the phenolic stabilizer, a hindered phenolic stabilizer is preferable, and for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,) 5-Di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N'-hexane-1,6 -Diylbis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (3,5-bis) 1,1-Dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, 3,3', 3 ", 5,5', 5" -hexa-tert-butyl-a, a', a "-(methicylene-) 2,4,6-triyl) tri-p-cresol, 4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-) m-tryl) propionate], hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-tert-butyl- 4-Hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4,6-bis (octylthio)) -1,3,5-triazin-2-ylamino) phenol, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate And so on.

Among them, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Pentaerythritol-tetrakis- (β-lauryl-thiopropionate) is preferred. Specific examples of such phenolic antioxidants include, for example, BASF (trade name, the same applies hereinafter) "Irganox 1010", "Irganox 1076", and ADEKA "ADEKA STUB AO-50". Examples thereof include "ADEKA STAB AO-60" and "ADEKA STAB AO-412S".
The hindered phenol-based stabilizer may contain one type, or two or more types may be contained in any combination and ratio.

The content of the phenolic stabilizer is preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). If the content is less than 0.01 parts by mass, the thermal stability tends to decrease, and if it exceeds 1 part by mass, the amount of generated gas may increase. A more preferable content is 0.05 to 0.8 parts by mass, and even more preferably 0.1 to 0.6 parts by mass.

[Release agent]
The resin composition of the present invention also preferably contains a mold release agent. As the release agent, known release agents usually used for thermoplastic polyester resins can be used, and among them, one or more mold release agents selected from polyolefin compounds, fatty acid ester compounds and silicone compounds. Agents are preferred.

Examples of the polyolefin compound include compounds selected from paraffin wax and polyethylene wax, and among them, those having a mass average molecular weight of 700 to 10,000, more preferably 900 to 8,000 are preferable. Further, a modified polyolefin compound in which a hydroxyl group, a carboxyl group, a hydroxyl group, an epoxy group or the like is introduced into the side chain is also particularly preferable.

Examples of the fatty acid ester-based compound include fatty acid esters such as glycerin fatty acid esters, sorbitan fatty acid esters, and pentaerythritol fatty acid esters, and partial saponified products thereof. Among them, the number of carbon atoms is 11 to 28, preferably carbon atoms. Mono- or di-fatty acid esters composed of fatty acids of numbers 17 to 21 are preferred. Specific examples thereof include glycerin monostearate, glycerin monobehenate, glycerin dibehenate, glycerin-12-hydroxymonostearate, sorbitan monostearate, pentaerythritol distearate, and pentaerythritol tetrastearate.

Further, as the silicone-based compound, a modified compound is preferable from the viewpoint of compatibility with the thermoplastic polyester resin (A) and the like. Examples of the modified silicone oil include silicone oil in which an organic group is introduced into the side chain of polysiloxane, silicone oil in which an organic group is introduced into both ends and / or one end of polysiloxane, and the like. Examples of the organic group to be introduced include an epoxy group, an amino group, a carboxyl group, a carbinol group, a methacryl group, a mercapto group, a phenol group and the like, and an epoxy group is preferable. As the modified silicone oil, a silicone oil in which an epoxy group is introduced into the side chain of polysiloxane is particularly preferable.

The content of the release agent is preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). If it is less than 0.05 parts by mass, the surface property tends to be deteriorated due to poor mold release during melt molding, while if it exceeds 2 parts by mass, the kneading workability of the resin composition is lowered and molding is performed. Cloudiness may be seen on the surface of the product. The content of the release agent is preferably 0.1 to 1.5 parts by mass, more preferably 0.3 to 1.0 parts by mass.

[Glidant]
The resin composition of the present invention also preferably contains a lubricant. Examples of the lubricant include paraffin oil, paraffin such as solid paraffin, higher fatty acid such as stearic acid, higher alcohol such as palmityl alcohol and stearic acid, calcium stearate, zinc stearate, barium stearate, aluminum stearate, magnesium stearate and the like. Metal salts of fatty acids, butyl stearate, glycerin monostearate, fatty acid esters such as diethylene glycol monostearate, stearoamide, methylene bisstearoamide, ethylene bisstearoamide, ethylenediamide of oxystearic acid, methylolamide, oleylamide. , Stearic acid amide, fatty acid amide such as erucic acid amide, and waxes such as carnauba wax and montan wax. Of these, calcium stearate is particularly preferable.
The content of the lubricant is preferably 0.01 to 2 parts by mass, and more preferably 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A).

[Other ingredients]
The resin composition of the present invention may contain various additives other than those described above as long as the effects of the present invention are not significantly impaired. Examples of such additives include flame retardants other than brominated polyacrylate-based flame retardants (B), flame retardants other than antimony compounds, ultraviolet absorbers, fillers, antistatic agents, antifogging agents, dyes and pigments. Fluorescent whitening agents, antiblocking agents, fluidity improving agents, plasticizers, dispersants, antibacterial agents and the like can be mentioned. These may be used in combination of two or more.
Examples of the flame retardant other than the brominated polyacrylate-based flame retardant (B) include brominated polycarbonate, brominated epoxy compound, brominated polystyrene, brominated polyphenylene ether and the like.

In addition, the polyester-based resin composition of the present invention may contain a thermoplastic resin other than the thermoplastic polyester resin (A) within a range that does not significantly impair the effects of the present invention. Specific examples of other thermoplastic resins include polyamide resin, polycarbonate resin, polyphenylene oxide resin, polyacetal resin, styrene resin (including ABS resin), polyphenylene sulfide ethylene resin, polysulfone resin, and polyether sulfone. Examples thereof include resins, polyetherimide resins, polyether ketone resins, and polyolefin resins. It is also preferable to contain various elastomers from the viewpoint of improving impact resistance.

[Manufacturing of resin composition]
The resin composition of the present invention is produced by mixing and melt-kneading each component. Specifically, the thermoplastic polyester resin (A), the brominated polyacrylate-based flame retardant (B), and each component to be blended as necessary are premixed using various mixers such as a tumbler and a Henschel mixer, and then Banbury. The resin composition can be produced by melt-kneading with a mixer, a roll, a brabender, a single-screw kneading extruder, a twin-screw kneading extruder, a kneader or the like.

Further, for example, the resin composition of the present invention may be produced without premixing each component or by premixing only a part of the components and supplying the components to an extruder using a feeder for melt kneading. You can also.
Further, for example, a resin composition obtained by premixing some components and supplying them to an extruder to be melt-kneaded is used as a masterbatch, and this masterbatch is mixed with the remaining components again and melt-kneaded. The resin composition of the present invention can also be produced.
When a fibrous material such as glass fiber is used as the filler, it is also preferable to supply the filler from the side feeder in the middle of the cylinder of the extruder.

The method for producing a resin molded product from the resin composition of the present invention is not particularly limited, and is a molding method generally adopted for thermoplastic polyester resins, that is, a general injection molding method or an ultrahigh-speed injection molding method. , Injection compression molding method, two-color molding method, hollow molding method such as gas assist, molding method using heat insulating mold, molding method using rapid heating mold, foam molding (including supercritical fluid), inserter Mold molding, IMC (immold coating molding) molding method, extrusion molding method, sheet molding method, thermal molding method, rotary molding method, laminated molding method, press molding method and the like can be adopted. It is also possible to select a molding method using a hot runner method. Injection molding is particularly preferable.

Since the polyester-based resin composition of the present invention has excellent flame retardancy, melt heat stability, and laser printability, it can be widely used in various applications, and can be widely used in electric devices, electronic devices, or other parts. It is particularly suitable as a relay, a switch, a connector, a breaker, an electromagnetic switch, a terminal switch, a sensor, an actuator, a microswitch, a microsensor, a microactor, and other contact-contact electrical and electronic equipment parts, and a housing of the electrical and electronic equipment. Can be preferably mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not construed as being limited to the following examples.
The components used in the following Examples and Comparative Examples are as shown in Table 1 below.
The GPC chart of the pentabromobenzyl polyacrylate (B-1, B-2 and BX) used is shown in FIG. The vertical axis is the weight fraction, and the horizontal axis is the common logarithmic value of the molecular weight M.

The pentabromobenzyl polyacrylates B-1 and B-2 in Table 1 above are obtained by washing the PBBPA produced by the above steps 1 to 4 as shown in Table 1.
The Na element concentrations of B-1, B-2 and BX were measured by fluorescent X-ray analysis, and those that were not detected were measured again by emission spectroscopy (ICP).
The Mg ion concentration and the Al ion concentration were measured by ICP emission spectroscopy.
The water used for cleaning the PBBPA was prepared using a commercially available ultrapure water production device "Simplicity UV" manufactured by Nippon Millipore Co., Ltd.

(Examples 1 and 2, Comparative Examples 1 and 2)
Each component listed in Table 1 above is blended in the amount shown in Table 2 below (all by mass), and a twin-screw extruder (“TEX30α” manufactured by Japan Steel Works, Ltd.) is used to set the barrel temperature to 260. The mixture was kneaded at ° C. and a screw rotation speed of 200 rpm, extruded into a strand, rapidly cooled in a water tank, and pelletized with a pelletizer to obtain pellets. The calcium stearate was dry-blended into the obtained pellets in an amount ratio of 0.1 parts by mass with respect to 100 parts by mass of the polybutylene terephthalate resin, and externally added to obtain pellets of the resin composition.

[Evaluation of thermal stability of fusion]
(1) Measurement of intrinsic viscosity of resin and intrinsic viscosity of pellets The intrinsic viscosity IV of the raw material polybutylene phthalate resin (mixture of mass ratio shown in Table 2) before preparation was measured at 30 ° C. (referred to as “preparation IV”). .. The intrinsic viscosity is a value (unit: dl / g) measured at 30 ° C. in a 1: 1 (mass ratio) mixed solvent of tetrachloroethane and phenol.
Then, the intrinsic viscosity IV of the resin composition pellet obtained above was measured (referred to as "pellet IV").
The percentage of pellet IV to charge IV ([pellet IV / charge IV] × 100) was determined and used as the intrinsic viscosity retention rate (unit:%). It can be said that the higher the value of the intrinsic viscosity retention rate, the less the resin is decomposed.

[Flame retardance]
The obtained resin composition pellets are burned in an injection molding machine (“NEX80” manufactured by Nissei Resin Industry Co., Ltd.) under the conditions of a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C. to a thickness of 12.5 mm × 125 mm × 0.75 mm. The test piece was injection molded. The flame retardancy was evaluated as follows.
Flame retardant (UL94):
According to the method of Subject 94 (UL94) of Underwriters Laboratories, flame retardancy was tested using five test pieces (thickness: 0.75 mm), and V-0, V-1, and V-2, Classified as non-conforming.
The above evaluation results are summarized in Table 2 below.

[Silver plate corrosion test]
50 g of the obtained resin composition pellets were placed in a glass wide-mouthed bottle with an internal volume of 120 ml, a silver plate (10 mm × 0.2 mmt) was placed on the resin composition pellets, and stored in an oven at 160 ° C. for 250 hours. , The degree of discoloration of the silver plate was visually observed, and the degree of discoloration was evaluated in the following three stages.
Level 1: No discoloration or almost no discoloration.
Level 2: Discolored, but to a lesser extent.
Level 3: Clearly discolored.

The polyester resin composition of the present invention has excellent flame retardancy, less mold corrosion during molding, less corrosion of metal parts even when used in close proximity to metal parts for a long time, and melt thermal stability. Therefore, it can be widely used in various applications, and can be particularly preferably used as an insulating component for electrical equipment, electronic equipment, or the like.

Claims (8)

A resin composition containing 3 to 60 parts by mass of the brominated polyacrylate-based flame retardant (B) with respect to 100 parts by mass of the thermoplastic polyester resin (A), and the mass of the brominated polyacrylate-based flame retardant (B). A polyester resin composition characterized in that the ratio (Mw / Mn) of the average molecular weight (Mw) to the number average molecular weight (Mn) is 5.5 or less. The polyester-based resin composition according to claim 1, wherein the Na element concentration measured by the fluorescent X-ray analysis method of the brominated polyacrylate-based flame retardant (B) is 500 ppm or less. The polyester-based resin composition according to claim 1 or 2, wherein the brominated polyacrylate-based flame retardant (B) has a mass average molecular weight (Mw) of 10,000 or more as measured by GPC. The invention according to any one of claims 1 to 3, wherein the brominated polyacrylate-based flame retardant (B) has a single peak molecular weight distribution, and the maximum peak position thereof is in the range of 20,000 to 50,000 molecular weight. Polyester resin composition. The polyester-based resin composition according to any one of claims 1 to 4, wherein the Mg ion concentration measured by ICP emission spectroscopic analysis of the brominated polyacrylate-based flame retardant (B) is 5 to 2000 ppm. The polyester resin composition according to any one of claims 1 to 5, wherein the Al ion concentration measured by ICP emission spectroscopic analysis of the brominated polyacrylate flame retardant (B) is 5 to 3000 ppm. The polyester-based resin composition according to any one of claims 1 to 6 , wherein the brominated polyacrylate-based flame retardant (B) is pentabromobenzyl polyacrylate. A molded product comprising the polyester-based resin composition according to any one of claims 1 to 7 .