JPH1060103A - Resin pellet and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin pellet suitable for molding of a self-supporting bottle, for beverages, which has excellent transparency and, when used for a slightly carbonated drink contg. fruit juice, can withstand heat in sterilization by hot water and pressure in expansion by carbon dioxide gas and, in addition, has low acetaldehyde content. SOLUTION: This resin pellet having an intrinsic viscosity of not less than 0.60 comprises a polyester (A) composed mainly of polyethylene terephthalate and a polyester compsn. (B) composed mainly of polyethylene terephthalate, polyallylate and/or polyethylene naphthalate. In this case, in the section of the resin pellet, the polyester (A) and the polyester compsn. (B) are present as layers independently of each other, and at least a part of the surface of the pellet is occupied by the polyester (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to containers for beverages such as soft drinks, seasonings, eye drops, detergents, etc., which are excellent in transparency and heat resistance and have an extremely low acetaldehyde content caused by decomposition of polyester. And a method for producing the same.

[0002]

2. Description of the Related Art In recent years, containers made of polyethylene terephthalate (PET) or a polyester mainly composed of PET (hereinafter referred to as "bottles") used for fruit-containing microcarbonated beverages and the like have a social aspect in addition to performance. It is required to have the required recyclability. For example, in the case of a carbonated beverage containing juice, hot water sterilization at about 65 ° C. for about 10 minutes is necessary.In this case, when a bottle filled with a slightly carbonated beverage containing juice is heated, the carbon dioxide gas inside expands. 0.05MP
a Internal pressure higher than a is generated, and the heat resistance of the conventional PET bottle is insufficient, and the conventional PET bottle cannot withstand the internal pressure. As a result, there arises such a problem that the bottom portion of no stretching or low stretching ratio swells, or the liquid level is lowered due to the swelling, so that the internal capacity is seen to be small. On the other hand, there is a problem that the cap is loosened due to lack of heat resistance even at the mouth of the bottle.

[0003] Usually, the side surface of a PET bottle is completely molecularly oriented by biaxial stretching, and thus shows sufficient heat resistance if heat set for a short time. Therefore, the side surface having the largest area has sufficient heat resistance and impact resistance even with conventional PET alone. However, the non-stretched portion of the mouth and the non-stretched or low-stretched portion of the bottom cannot withstand the internal pressure of carbon dioxide gas expansion due to hot water sterilization at about 65 ° C. for about 10 minutes at a fruit juice-containing carbonated beverage.

As a method for increasing the heat-resistant pressure of the unstretched portion of the mouth, for example, a method by crystallization (Japanese Patent Publication No. 59-331)
No. 01) and the mouth insert piece method (Japanese Unexamined Patent Publication No.
No. 4730, Japanese Patent Publication No. 6-88318, Japanese Patent Publication No. 7-3305
No. 4) has been proposed. According to these methods, it is possible to withstand not only 65 ° C. of hot water sterilization but also 80 ° C. or more. In addition, there is no particular problem in impact resistance because of the cap.

[0005] Therefore, in a bottle for a slightly carbonated beverage containing fruit juice, it is an important issue how to impart heat resistance to the non-stretched or low-stretched portion at the bottom.
At present, the bottom of a PET bottle used in this field has a round shape and is pressure-resistant, and the mouth is crystallized to have heat resistance. In this method, of course, the bottle cannot be made self-supporting. Therefore, usually, the bottle is made self-supporting by a method of bonding a polyethylene base cup to the round bottom (base cup method). I have. However, in this method, the cost increases because the separately formed base cup is bonded after the bottle is formed, and further, when recycling,
There was a problem that this base cup had to be removed together with the adhesive.

In order to solve the above-mentioned problems of the base cup method, for example, a bottle using a resin composition comprising PET, polyethylene naphthalate (PEN) and a metal salt of a specific higher fatty acid has been proposed. (Japanese Unexamined Patent Publication No. 2-2768
No. 55). However, in this bottle, PET and PEN
However, there is a problem that the appearance such as transparency is inferior due to insufficient compatibility with water.

[0007] Also, polyarylate (PAR) is added to PET.
(Japanese Patent Laying-Open No. 59-204552,
JP-A-1-214423) and a self-standing bottle in which PAR is mixed with PET to have heat resistance (JP-A-7-242222).
Publication). However, in these bottles, PAR having a high melting point is melt-mixed, so that the extrusion temperature generally becomes high, and as a result, a material having an acetaldehyde content of about several tens ppm due to the decomposition of PET is used. However, it was not suitable for beverage use.

On the other hand, in the case of a self-supporting PET bottle, it is a general method to support the bottle with five bulges at the bottom in order to withstand internal pressure and to use PET having a high intrinsic viscosity. PET / PAR started to be used
This method is also used for alloy resins. However, this method has a problem that PET is easily decomposed because the molding is usually performed at a temperature higher than the melting point of PAR, and tens ppm or more of acetaldehyde is contained. There is also a problem that the obtained bottle lacks in quality stability. Therefore, bottle molding manufacturers have demanded a bottle resin that can be produced with stable quality, can be recycled, and has a low acetaldehyde content and excellent heat resistance and pressure resistance.

As a method of solving the above problems, the present inventors have proposed a resin composition in which PET or a polyester mainly composed of PET and a specific composition of PAR are blended (Japanese Patent Application No. 8-45793). Also, a resin composition (Japanese Patent Application No. 8-82278) in which PET or a polyester mainly composed thereof, a PAR having a specific composition and PEN or a polyester mainly composed thereof is blended in a specific amount has been previously proposed. The present invention has been made for the purpose of improving this and further increasing the heat resistance of the bottle.

[0010]

DISCLOSURE OF THE INVENTION The present invention is directed to a beverage product having excellent transparency, heat resistance during hot water sterilization of a slightly carbonated beverage containing fruit juice and pressure resistance against carbon dioxide gas expansion, and having a low acetaldehyde content. It is intended to provide resin pellets suitable for molding a self-supporting bottle for use.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that PET or polyester mainly composed of PET, PAR and / or PEN.
Alternatively, the present inventors have found that this object can be achieved by forming a pellet having a specific cross-sectional shape using a polyester mainly composed of the polyester, and then subjecting the pellet to solid-phase polymerization, and reached the present invention.

That is, the gist of the present invention is as follows. (1) A resin pellet having an intrinsic viscosity of 0.60 or more, comprising a polyester (A) and a polyester composition (B),
The polyester (A) and the polyester composition (B) have a cross-sectional form in which the polyester (A) exists as an independent layer, and the polyester (A) has a cross-sectional form in which at least a part of the surface of the pellet is occupied. Resin pellets. Here, the polyester (A) is PET or a polyester based on the polyester, and the polyester composition (B) is a PET or a polyester based on the same, PAR and / or a polyester composed of PEN or a polyester based on the same. A composition, PA
The ratio of R and / or PEN or a polyester mainly composed thereof to the resin pellets is 1 to 10% by weight. (2) In producing resin pellets from the polyester (A) and the polyester composition (B), the polyester (A) and the polyester composition (B) have a cross-sectional form in which they are present as independent layers, and the polyester ( A)
The method for producing resin pellets according to the above (1), wherein the resin pellets are melt-molded into pellets so as to form a cross section occupying at least a part of the surface of the pellets, and then subjected to solid-phase polymerization.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The resin pellet in the present invention is composed of the polyester (A) and the polyester composition (B), and must have an intrinsic viscosity of 0.60 or more. If the intrinsic viscosity is less than 0.60, the mechanical properties are reduced, and a practically usable bottle cannot be obtained.

The resin pellets have a cross-sectional form in which the polyester (A) and the polyester composition (B) exist as independent layers, and the polyester (A)
Must have a cross-sectional shape that occupies at least a part of the surface of the pellet. At this time, if the polyester (A) and the polyester composition (B) do not exist as independent layers, a transesterification reaction easily occurs between the polyesters during solid-phase polymerization, and the heat resistance decreases. In addition, if the polyester composition (B) appears on the entire surface of the pellet, it is not preferable because fusion between the pellets is likely to occur during solid phase polymerization.

As the resin pellet having the above-mentioned cross-sectional shape, for example, a core-sheath shape as shown in FIG.
As shown in FIGS. 1 (b) to 1 (d), there can be mentioned those having a layered structure of 16 layers or less alternately.

In the present invention, the polyester (A) comprises P
ET or a polyester mainly composed of ET, and is produced by a polycondensation reaction using a terephthalic acid component and an ethylene glycol component as main components.

The polyester (A) includes, in addition to the above components, aromatic dicarboxylic acid components such as phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and diphenylsulfondicarboxylic acid. , Oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid,
Aliphatic dicarboxylic acid components such as azelaic acid, itaconic acid and maleic acid, diethylene glycol, triethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5- Aliphatic diol components such as pentanediol, 1,6-hexanediol, neopentyl glycol,
An alicyclic diol component such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol, and an aromatic diol component such as an ethylene oxide adduct of bisphenol A or bisphenol S are contained within a range that does not impair the properties of PET. You may.

The polyester composition (B) in the present invention
Is PET or a polyester based on PET or P
It is composed of AR and / or PEN or a polyester mainly composed of AR and / or PEN.

PAR is an aromatic polyester obtained by polymerization of a terephthalic acid component and / or isophthalic acid component as an aromatic dicarboxylic acid and a bisphenol A component as a dihydric phenol. The molar ratio between the terephthalic acid component and the isophthalic acid component in the PAR can be arbitrarily selected, but is preferably in the range of 40/60 to 60/40.

Further, PEN or a polyester mainly composed of PEN is produced by a polycondensation reaction between a 2,6-naphthalenedicarboxylic acid component and an ethylene glycol component.

In addition to the above components, PEN contains phthalic acid,
Aromatic dicarboxylic acid components such as isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, itaconic acid, and maleic acid Aliphatic dicarboxylic acid components such as, diethylene glycol, triethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
Aliphatic diol components such as 1,6-hexanediol and neopentyl glycol; alicyclic diol components such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol; ethylene oxide adducts of bisphenol A and bisphenol S; PEN as aromatic diol component
May be contained in a range that does not impair the characteristics of the above.

The ratio of PAR and / or PEN or a polyester mainly composed of PAR and / or PEN in the resin pellets should be 1 to 10% by weight, more preferably 3 to 7% by weight. If this proportion is less than 1% by weight, heat resistance and pressure resistance cannot be simultaneously satisfied. Conversely, if this proportion exceeds 10% by weight, solid-state polymerization is hindered, and the color tone deteriorates, which is not preferable.

When PAR and PEN or a polyester mainly composed of PAR are used in combination, the mixing ratio is preferably in the range of 20/80 to 80/20 by weight.

The polyester (A) or the polyester composition (B) in the present invention preferably contains an antioxidant. As the antioxidant, a hindered phenol antioxidant or a phosphorus antioxidant is used,
These may be used alone or in combination.

Examples of the hindered phenolic antioxidants include ADK STAB AO-20 and AO-3 manufactured by Asahi Denka Co., Ltd.
0, AO-40, AO-50, AO-60, AO-70, AO-80, Sumilizer GA-80 and BHT manufactured by Sumitomo Chemical Co., Ltd., and Irganoccus 1010 manufactured by Ciba Geigy.

Examples of the phosphorus-based antioxidant include triaryl phosphite, alkylaryl phosphite, and alkyl phosphite. For example, Asahi Denka's PEP-
24G, PEP-36, Sumilizer P-16 manufactured by Sumitomo Chemical Co., Ltd., and Irgafoss 168 manufactured by Ciba Geigy.

The addition amount of the antioxidant is desirably 2% by weight or less. If the amount exceeds 2% by weight, the color tone of the bottle deteriorates, which is not preferable.

Further, the polyester (A) or the polyester composition (B) may contain, in addition to the antioxidant, an ultraviolet absorber, a colorant and a heat stabilizer as long as the properties of the resin pellet of the present invention are not impaired. And the like.

Next, a method for producing the resin pellet of the present invention will be described. In the method of the present invention, first,
The polyester (A) and the polyester composition (B) are melt-formed so as to have a cross-sectional form in which the polyester (A) and the polyester composition (B) exist as independent layers, and have a cross-sectional form in which the polyester (A) occupies at least a part of the pellet surface. It is necessary to make pellets.

For example, a resin pellet having a core-sheath cross section as shown in FIG. 1 (a) is prepared by melting polyester (A) produced by a continuous melt polymerization apparatus so that the polyester (A) is on the sheath side of a core-sheath type die head. While supplying in a state, the melt of the polyester composition (B) blended in a specific ratio is placed on the core side of the core-sheath type die head, and the ratio of PAR and / or PEN or the polyester mainly containing this in the resin pellet is It can be manufactured by supplying the mixture in an amount of 1 to 10% by weight and extruding it into a strand.

A resin pellet having a layered cross section as shown in FIGS. 1 (b) to 1 (d) is divided into 2 ⁿ (n is the number of elements) layers mounted in a pipe. The polyester (A) and the polyester composition (B) can be manufactured by a method in which a polyester (A) and a polyester composition (B) are supplied in a molten state to a static mixer (N-20, manufactured by Noritake Company).

At this time, when one element is used, a pellet having a two-layer structure having the cross-sectional shape shown in FIG. 1B is obtained. In the case of two elements, a pellet having a four-layer structure having the cross-sectional shape shown in FIG. 1C is obtained. In the case of three elements, an eight-layered pellet having the cross-sectional shape shown in FIG. 1D is obtained. In the case of four elements, a 16-layered pellet is obtained. In the case of five elements, a 32-layered pellet is obtained. The number of layers is preferably a layered structure having 16 or less layers alternately. In the case of a structure having more than 32 layers, it is difficult to form resin pellets having a cross-sectional morphology which are present as alternately independent layers, and furthermore, transesterification between polyesters easily occurs during solid-state polymerization, resulting in heat resistance. It is not preferable because the property is lowered.

In order to produce a resin pellet having the above-mentioned cross-sectional form, the intrinsic viscosity of the polyester (A) is preferably 0.40 or more. If the intrinsic viscosity is less than 0.40, the kneadability with the polyester composition (B) is poor, and the solid-phase polymerization requires a long time, so that a practically usable bottle cannot be obtained. The intrinsic viscosity of the polyester composition (B) is also preferably 0.40 or more. If the intrinsic viscosity is less than 0.40, a bottle that requires a long time for solid-phase polymerization, has poor kneading properties with the polyester (A), and requires a long time for the solid-phase polymerization, and can be used for practical use. Is not preferred since

In the present invention, the above resin pellets are then subjected to solid phase polymerization. The solid-phase polymerization is preferably performed at a temperature lower than the melting point of the resin pellets for 10 hours or more under reduced pressure or flowing nitrogen gas. In this case, the solid-state polymerization temperature is more preferably 10 ° C. lower than the melting point of the resin pellet and 190 ° C. or higher. If the temperature is lower than 190 ° C., the solid phase polymerization does not proceed sufficiently, and if the temperature is near the melting point of the resin pellets, the pellets are naturally fused, which is not preferable.
On the other hand, if the solid phase polymerization time is less than 10 hours, the acetaldehyde content exceeds 10 ppm, and it is not preferable because resin pellets usable for beverage bottles cannot be obtained.

When resin pellets containing an appropriate amount of an antioxidant are subjected to solid phase polymerization, coloring during solid phase polymerization is prevented.
Resin pellets having better color tone can be obtained.

The resin pellets obtained by the above-mentioned production method have an intrinsic viscosity of 0.60 or more and usually have an acetaldehyde content of 10 ppm or less, and are molded into a bottle.

To manufacture a bottle using the resin pellets of the present invention, the apparatus used for stretch blow molding of PET can be used as it is. Specifically, a method is employed in which a preform is formed by injection molding using the above resin pellets, and then the preform is heated to perform biaxial stretch blow molding.

At this time, the temperature of each part of the cylinder and the nozzle of the molding machine is usually from 250 to 270 ° C. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction.

[0040]

In the resin pellets of the present invention, PET or a polyester (A) containing the same as a main component, PET or a polyester containing the same as a main component, and heat-resistant P
The polyester composition (B) comprising AR and / or PEN or a polyester mainly composed of AR and / or PEN has a cross-sectional form existing as an independent layer, and the polyester (A) occupies at least a part of the surface of the pellet. Because of its cross-sectional shape, transesterification during solid-state polymerization is suppressed, and the acetaldehyde content is also extremely small, so when used as a beverage bottle, heat resistance and pressure resistance are increased, And the taste and aroma of the contents are not impaired.

[0041]

Next, the present invention will be described specifically with reference to examples. In the examples, the characteristic values were measured as follows. Section Form The section of the resin pellet was observed with a microscope. Intrinsic viscosity [η] Measured at a temperature of 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent, and expressed in units of dl / g. Acetaldehyde content 2.5 g of resin pellets were sealed in a glass tube together with 10 ml of distilled water, extracted at 160 ° C. for 2 hours, cooled to 5 ° C. or lower, and acetaldehyde in the extract was subjected to gas chromatography (manufactured by Shimadzu Corporation). GC-14A). B value representing the color tone The color tone of the resin pellet was measured using a color difference meter (ND- # 80, manufactured by Nippon Denshoku Industries Co., Ltd.). The b value represents a yellow-blue color tone (yellow on the + side and bluish on the-side). The smaller the value, the better, unless it is extremely small. Heat resistance of bottles Bottles obtained by stretch blow molding using resin pellets (self-standing bottles with 5 point bulges at the bottom)
The vessel was filled with 1.5 liters of water, 5.7 g of dry ice was added thereto, sealed, and left for one week. Next, the sealed bottle was immersed in hot water controlled at 70 ° C. for 30 minutes, cooled with cold water, and visually checked for a change in the volume of the bottle. ：: Small volume change and usable as a self-contained bottle ×: Large volume change and cannot be used as a self-contained bottle

Reference Example 1 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 50 parts by weight of ethylene glycol and calcium acetate monohydrate 0.1 part by weight.
06 parts by weight were charged into a transesterification reactor, and the temperature was raised to 140 to 230 ° C. over 4 hours in a nitrogen gas atmosphere, and a transesterification reaction was performed while distilling off generated methanol outside the system. The resulting reaction product was added to sodium phosphate 0.05
Parts by weight and 0.03 parts by weight of germanium dioxide were added and transferred to the polymerization tank. Then, from 1013 hPa to 1.3 over 1 hour
Depressurized to hPa, and simultaneously from 230 ° C to 285 over 1.5 hours
C. and a polycondensation reaction was carried out under a reduced pressure of 1.3 hPa at a temperature of 285.degree. C. for 2 hours to obtain PEN. [Η] of this PEN was 0.64.

Example 1 PET of [η] 0.55 produced by a continuous melt polymerization apparatus was
The melt was supplied so as to be on the sheath side of the core-sheath type die head. On the other hand, [η] 0.65 PET and PAR (U-polymer, manufactured by Unitika Ltd.) produced by a continuous melt polymerization apparatus were added to P
PET / PAR alloy resin obtained by kneading using a twin-screw extruder so that the compounding amount of AR becomes 40% by weight,
It is melted by a single screw extruder, supplied to the core side of the core-sheath type die head so that the blending amount of PAR in the resin pellets becomes 6% by weight, extruded into a strand shape, and [η] 0.56 core-sheath shape. A resin pellet was obtained. Next, the resin pellets were dried with hot air at 130 ° C. for 5 hours, and then subjected to continuous solid-state polymerization at 210 ° C. for 15 hours under a flow of heated nitrogen gas to obtain [η] 0.84
Was obtained. Using this resin pellet,
The temperature of each part of the cylinder and the nozzle is 280 ° C, and the mold temperature is
The preform was molded using an injection molding machine (Nissei ASB Co., Ltd., Model ASB-50HT) set at 20 ° C., an injection time of 8 seconds, and a cooling time of 10 seconds. The preform is then
In a 0 ° C. atmosphere, blow molding was performed at a blow pressure of 2 MPa to produce a self-standing bottle having an average body pressure of 300 μm and an inner volume of 1.5 liter.

Example 2 The same PAR as that used in Example 1 was added to a PET discharge line of [η] 0.55 produced by a continuous melt polymerization apparatus.
The PAR / PET alloy resin of the blending amount (40% by weight) is supplied in a molten state so that the blending amount of the PAR in the resin pellets becomes 6% by weight, and the static mixer (Noritake) mounted in the pipe is supplied. The mixture was extruded into a strand shape by N-20 type (manufactured by Company Ltd., 2 elements), and resin pellets having a four-layer structure with [η] 0.56 were obtained. Next, the pellets were subjected to solid-phase polymerization in the same manner as in Example 1 to obtain resin pellets having [η] of 0.86, and a self-standing bottle was prepared using the pellets.

Example 3 An 8-layer resin pellet having an [η] of 0.76 was obtained in the same manner as in Example 2 except that the number of elements in the static mixer was changed to 3, and a self-standing type was prepared. A bottle was made.

Examples 4 to 7 Except that the amount of PAR or PEN was changed as shown in Table 1,
A core-sheath resin pellet was obtained in the same manner as in Example 1, and a self-standing bottle was prepared using the pellet.

Comparative Example 1 A resin pellet having a 32-layer structure of [η] 0.71 was obtained in the same manner as in Example 2 except that the number of elements in the static mixer was changed to 5, and a self-standing type A bottle was made.

Comparative Examples 2 and 3 Except that the amount of PAR or PEN was changed as shown in Table 1,
A core-sheath resin pellet was obtained in the same manner as in Example 1, and a self-standing bottle was prepared using the pellet.

COMPARATIVE EXAMPLE 4 The same procedure as in Example 1 was repeated except that PET of [η] 0.55 was used on the core side and PET / PAR alloy resin containing 40% by weight of PAR was used on the sheath side. A resin pellet was obtained, and solid phase polymerization was performed using the pellet. However, the pellets were fused to each other and solid phase polymerization was not performed.

Comparative Example 5 A core-in-sheath resin pellet was obtained in the same manner as in Example 1 except that the solid-phase polymerization time was changed to 9 hours, and a self-standing bottle was prepared using the pellet.

Comparative Example 6 As the charged polyester, PET of [η] 0.35,
A core-in-sheath pellet was obtained in the same manner as in Example 4 except that PAR of [η] 0.51 and PEN of [η] 0.37 were used, and a self-standing bottle was produced using the pellet.

Table 1 shows the amounts of PAR and / or PEN, the cross-sectional morphology of the resin pellets, [η], the acetaldehyde content, the color tone, and the heat resistance of the bottles in Examples 1 to 7 and Comparative Examples 1 to 6. Indicated.

[0053]

[Table 1]

[0054]

According to the present invention, beverages having excellent transparency, heat resistance during hot water sterilization of fruit juice-containing microcarbonated beverages, pressure resistance against carbon dioxide gas expansion, and low acetaldehyde content are obtained. Resin pellets suitable for forming a free-standing bottle can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross section of a resin pellet. (a)
Is a core-sheath shape, (b) is a two-layer structure, (c) is a four-layer structure, and (d) is an eight-layer structure.
Represents the layer structure.

[Explanation of symbols]

 A Polyester (A) B Polyester composition (B)

Claims (3)

[Claims] 1. A resin pellet comprising a polyester (A) and a polyester composition (B) having an intrinsic viscosity of 0.60 or more, wherein the polyester (A) and the polyester composition (B) are present as independent layers. A resin pellet having a cross-sectional shape and having a cross-sectional shape in which the polyester (A) occupies at least a part of the surface of the pellet. Here, polyester (A)
Is a polyester composition comprising polyethylene terephthalate or a polyester comprising the same, and the polyester composition (B) is a polyester composition comprising polyethylene terephthalate or a polyester comprising the same, polyarylate and / or polyethylene naphthalate or a polyester comprising the same. The ratio of polyarylate and / or polyethylene naphthalate or a polyester mainly composed of the same to the resin pellets is 1 to 10% by weight. 2. The resin pellet according to claim 1, wherein the cross section of the resin pellet has a core-sheath shape or a layered structure of 16 layers or less alternately. 3. When producing a resin pellet from the polyester (A) and the polyester composition (B), the polyester (A) and the polyester composition (B) have a cross-sectional form in which they are present as independent layers, and After the polyester (A) is melt-molded to have a cross-sectional shape such that the polyester (A) occupies at least a part of the surface of the pellet, the pellet is formed.
The method for producing a resin pellet according to claim 1, wherein the solid phase polymerization is performed.