JPH11172084A - Production of polyethylene terephthalate resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyethylene terephthalate resin composition with an improved rate of crystallization by rendering the crystallization temperature lowered without reducing clarity. SOLUTION: Spherical particles of a polyethylene terephthalate resin having an average particle diameter of 1-6 mm, a maximum particle diameter of at most 1.2 times the average particle diameter and a minimum particle diameter of at least 0.8 time the average particle diameter are brought into contact with a member composed of a crystalline thermoplastic resin of a different type therefrom under fluidizing conditions to incorporate trace amounts of the crystalline thermoplastic resin thereinto and subsequently, melt kneaded and formed into a polyethylene terephthalate resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a polyethylene terephthalate resin composition, and more particularly, to a method for lowering the crystallization temperature without lowering the transparency, especially for bottles for food packaging and the like. The present invention relates to a method for producing a polyethylene terephthalate resin composition useful for molding.

[0002]

2. Description of the Related Art Conventionally, as bottle containers for carbonated drinks, fruit juice drinks, alcoholic drinks, drinks such as tea and mineral water, liquid seasonings, edible oils, liquid detergents, cosmetics, and the like.
Polyethylene terephthalate resins have attracted attention in terms of excellent transparency, gas barrier properties, safety and health, and the like in addition to excellent mechanical properties and chemical properties, and have shown remarkable growth.

[0003] These polyethylene terephthalate resin bottle containers are usually formed by stretch-blow-molding an injection-molded preform in a blow mold. However, contents such as fruit juice drinks that require hot filling are used. In the case of a container, in order to increase the heat resistance of the bottle, the preform or the plug portion of the bottle is heat-treated and crystallized. In order to increase the density of the body, the temperature of the blow mold is set to 120 to 180.
It has been practiced to set the temperature as high as about ° C. to promote crystallization of the body. However, since polyethylene terephthalate resin has a low crystallization rate, there is a problem that these treatments at the time of bottle molding require time, and improvement thereof has been strongly demanded conventionally.

On the other hand, the inventor of the present invention first contacted a polyethylene terephthalate resin chip with a member made of a polyethylene resin under flow conditions to allow the polyethylene terephthalate resin to contain the polyethylene resin.
A method for lowering the crystallization temperature of polyethylene terephthalate resin has been proposed (see JP-A-9-71639). However, although this method provides some improvement in the crystallization rate of the polyethylene terephthalate resin, it has been difficult to say that it has sufficiently satisfied the market requirements in balance with transparency.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a method for producing a polyethylene terephthalate resin composition having an improved crystallization rate by lowering the crystallization temperature without lowering the transparency. The purpose is to provide.

[0006]

Means for Solving the Problems The present invention has been made to achieve the above object, that is, the present invention has an average particle size of 1 to 6 mm and a maximum particle size of the average particle size. 1.2 times or less the diameter, and the minimum particle diameter is 0.1 mm of the average particle diameter.
8 times or more, spherical particles of polyethylene terephthalate resin, under flowing conditions, after contacting a member made of a crystalline thermoplastic resin different from the resin to contain a small amount of the crystalline thermoplastic resin, A method for producing a polyethylene terephthalate resin composition which is melt-kneaded to form a polyethylene terephthalate resin composition is summarized.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the polyethylene terephthalate resin includes a dicarboxylic acid unit mainly composed of terephthalic acid or its alkyl (about 1 to 4 carbon atoms) ester and a glycol unit mainly composed of ethylene glycol. The oxyethylene oxyterephthaloyl unit preferably accounts for at least 80 equivalent% of all the constituent units. Further, the content of diethylene glycol units is 1 to 4 mol% based on all glycol units.
Is preferably within the range.

The dicarboxylic acid units other than terephthalic acid and its alkyl ester include, for example, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid,
Aromatic dicarboxylic acids such as 4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid, and malonic acid , Succinic acid, adipic acid, azelaic acid, aliphatic dicarboxylic acids such as sebacic acid, and as a glycol unit other than ethylene glycol, for example, propylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, Aliphatic glycols such as decamethylene glycol, neopentyl glycol and diethylene glycol, 1,1-cyclohexane dimethylol,
Alicyclic glycols such as 4-cyclohexane dimethylol, 4,4'-dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane ,
Bis (4-hydroxyphenyl) sulfone, bis (4-
aromatic glycols such as (β-hydroxyethoxyphenyl) sulfonic acid, and further one or more kinds of, for example, hydroxycarboxylic acids and alkoxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid; Used as a copolymer component.

The raw materials containing these dicarboxylic acid units containing terephthalic acid or an alkyl ester thereof as a main component and glycol units containing ethylene glycol as a main component include:
According to a conventional method, an esterification reaction or a transesterification reaction is carried out at a temperature of about 240 to 280 ° C. and a pressure of about 1 to 3 kg / cm ^{2 in} the presence of an esterification catalyst or a transesterification catalyst such as a metal compound such as manganese. After being converted to bis (β-hydroxyethyl) terephthalate and / or an oligomer thereof, the reaction is carried out in the presence of a polycondensation catalyst such as a metal compound such as germanium and a stabilizer such as a phosphorous compound such as phosphoric acid.
Melt polycondensation is performed at a temperature of about 00 ° C. and a pressure of about 500 to 0.1 mmHg to form a polymer, which is drawn out in a strand shape from a draw-out port provided at the bottom of the melt polymerization tank, and then cut by a cutter. Into particles, and
The particulate polymer obtained by the melt polycondensation is usually 1
After being pre-crystallized by heating at a temperature of about 20 to 200 ° C. for 1 minute or more, under a flow of inert gas such as nitrogen, 190
Temperature of about 230 ° C, 1kg / cm ² -10mmHg
Solid-phase polymerization is performed at a pressure of about 1 to 50 hours to obtain a particulate polyethylene terephthalate resin.

[0010] In the present invention, the crystalline thermoplastic resin different from the resin constituting the member for bringing the particles of the polyethylene terephthalate resin into contact with each other under flowing conditions is typically a polyolefin resin or polyamide. And the like.

Examples of the polyolefin resin include those having 2 to 2 carbon atoms such as ethylene, propylene and butene-1.
About 8 α-olefin homopolymers, those α-olefins, and ethylene, propylene, butene-1,3-
Other α-olefins having about 2 to 20 carbon atoms such as methylbutene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1 and the like, vinyl acetate, vinyl chloride, acrylic acid , Methacrylic acid, acrylic acid ester, methacrylic acid ester, copolymers with vinyl compounds such as styrene, and the like. Specifically, for example, low-, medium-, and high-density polyethylene (branched or linear) Ethylene homopolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-4-
Methylpentene-1 copolymer, ethylene-hexene-1
Ethylene resins such as copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer Propylene resins such as propylene homopolymer, propylene-ethylene copolymer, propylene-ethylene-butene-1 copolymer, and butene-1 homopolymer, butene-1-ethylene copolymer, butene-1 Butene-1 resin such as propylene copolymer;

Examples of the polyamide resin include lactam polymers such as butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, ω-laurolactam, 6-aminocaproic acid, 11-aminoundecanoic acid, and the like. Polymers of aminocarboxylic acids such as 12-aminododecanoic acid, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, undecamethylenediamine, 2,2,4- or 2,4,4-trimethylhexa Aliphatic diamines such as aliphatic diamines such as methylene diamine, 1,3- or 1,4-bis (aminomethyl) cyclohexane and bis (p-aminocyclohexylmethane), and aromatic compounds such as m- or p-xylylenediamine Diamine units such as aromatic diamines, glutaric acid and adipine , Suberic acid, polycondensates of aliphatic dicarboxylic acids such as sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, terephthalic acid, and dicarboxylic acid units and aromatic dicarboxylic acids such as isophthalic acid,
And copolymers thereof. Specific examples thereof include nylon 4, nylon 6, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, nylon 66, nylon 69, nylon 610, and nylon 61.
1, nylon 612, nylon 6T, nylon 6I, nylon MXD6, nylon 6/66, nylon 6/61
0, nylon 6/12, nylon 6 / 6T, nylon 6
I / 6T and the like.

In the present invention, the particles of the polyethylene terephthalate resin are brought into contact with a member made of the above-mentioned crystalline thermoplastic resin under flowing conditions to contain a small amount of the crystalline thermoplastic resin and then melt-kneaded. To produce a polyethylene terephthalate resin composition.

In this case, it is preferable that particles of the polyethylene terephthalate resin be brought into collision with the member in a space where the member made of the crystalline thermoplastic resin exists in the space where the member made of the crystalline thermoplastic resin exists. , Immediately after melt polymerization of polyethylene terephthalate resin, immediately after preliminary crystallization, immediately after solid phase polymerization, etc., and when filling and discharging a transport container in the transport stage of polyethylene terephthalate resin particles as a product, and polyethylene terephthalate. At the time of injection of a molding machine at the molding stage of resin particles, a part of a pneumatic transport pipe, a gravity transport pipe, a silo, a punching plate of a vibrating sieve, a magnet part of a magnet catcher, etc. are made of crystalline thermoplastic resin, Or lining a crystalline thermoplastic resin, or a rod-like or net-like body in the transfer path And the like installing-crystalline thermoplastic resin member, and a method of transferring particles of the polyethylene terephthalate resin.

In this case, the particles of the polyethylene terephthalate resin have an average particle diameter of 1 in the present invention.
-6 mm, and the maximum particle size is 1.
It is essential to use spherical particles having a particle diameter of not more than twice and a minimum particle diameter of not less than 0.8 times the average particle diameter. If the particles are not spherical, and even if spherical, the average particle size range, the upper limit of the maximum particle size, if the minimum particle size is out of the lower limit, the effect of lowering the temperature of crystallization as a resin composition. Will be insufficient.

In the present invention, the average particle diameter of the polyethylene terephthalate resin spherical particles is such that the particles are placed on an xy plane when three axes perpendicular to each other in the shape per particle are x, y, and z. The maximum width a in the xy plane when measured with a vernier caliper perpendicular to the z-axis direction with respect to the xy plane, x in the yz plane without changing the position of the particles
The maximum width b in the yz plane when measured with a vernier caliper perpendicular to the axial direction, and zx when similarly measured with a vernier caliper from the y-axis direction to the zx plane without changing the position of the particles.
Each of the maximum widths c in the plane was measured for 100 arbitrary particles, the average values of a, b, and c were calculated from those values, and the average values were further averaged. .

In order to make the shape of the polyethylene terephthalate resin particles within the above range, the resin drawn out in a strand shape from the outlet provided at the bottom of the melt polymerization tank as described above is cut with a cutter, or In extruding the resin after the solid phase polymerization into a strand shape with an extruder and cutting it with a cutter, for example, a method of providing a cooling water tank immediately after drawing or extruding, cutting with an underwater cutter, and then cooling is used.

In the present invention, the contact time of the polyethylene terephthalate resin particles with the member is usually 0.0
Although it is an extremely short time of about 1 to 1 second, a very small amount of crystalline thermoplastic resin can be contained in the polyethylene terephthalate resin. The content ratio of the crystalline thermoplastic resin in the polyethylene terephthalate resin composition is 0.1 to
It is preferably 100 ppb, particularly preferably 1 to 50 ppb. If the content is less than the above range, the effect of lowering the temperature of crystallization as the resin composition becomes insufficient,
On the other hand, when the content exceeds the above range, the transparency of the resin composition tends to be impaired. The intrinsic viscosity of the polyethylene terephthalate resin composition is preferably 0.6 to 1.0 dl / g as a value measured at 30 ° C. in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1). .

The polyethylene terephthalate resin composition of the present invention produced by the above method is formed into a film or a sheet by extrusion, for example, or into a preform by injection molding, and then into a bottle by blow molding. Etc. Extrusion molding conditions at this time are within a range usually employed, for example, a cylinder temperature of 240 to 300 ° C., a screw rotation speed of 40 to 300 rpm, and a discharge pressure of 40 to 140 kg / c.
m ² , cooling drum temperature 5 to 40 ° C., etc. The injection molding conditions include a cylinder temperature of 270 to 300 ° C., a mold temperature of 5 to 40 ° C., a screw rotation speed of 40 to 300 rpm, and an injection pressure of 40 to 140 kg.
/ Cm ² or the like.

The polyethylene terephthalate resin composition according to the production method of the present invention can lower the crystallization temperature during molding. Specifically, the polyethylene terephthalate resin composition can be obtained by a differential scanning calorimeter of a resin composition formed into a molded product. Warm crystallization temperature of 145 to 1
The temperature is preferably 70 ° C., particularly preferably 155 to 165 ° C. Here, the elevated crystallization temperature refers to the top temperature of the crystallization peak observed during the course of heating from room temperature to 285 ° C. at a rate of 20 ° C./min with a differential scanning calorimeter. .

Among the molded articles obtained by the above molding methods, the resin composition according to the present invention is used to form a bottle by a blow molding method such as a cold parison method in which a preform obtained by an injection molding method is biaxially stretched after reheating. Suitable for molding, for example, carbonated beverages, fruit juice beverages, alcoholic beverages, beverages such as tea and mineral water, soy sauce, sauces,
It is suitably used as a container for liquid seasonings such as mirin and dressings, edible oils, liquid detergents and cosmetics.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist. Example 1 13.0 kg of terephthalic acid and 5.8 of ethylene glycol
2 kg of a slurry is prepared, and 0.30 kg of bis (2-hydroxyethyl) terephthalate is added in advance to prepare a slurry.
The mixture was sequentially supplied to the esterification tank maintained at a temperature of 50 ° C. over 4 hours. After completion of the supply, the esterification reaction was allowed to proceed for 1 hour, and then half of the mixture was transferred to a polycondensation tank, and phosphoric acid was added at 0.9%.
1 g and 0.92 g of germanium dioxide,
The temperature was gradually raised from 278 ° C. to 278 ° C., the pressure was gradually reduced from normal pressure, and the polycondensation reaction was performed for 3 hours while maintaining the pressure at 0.5 mmHg. Then, the produced polymer was directly connected to the cooling water tank at the bottom of the polycondensation tank. It was extracted in a strand form from the extraction opening provided and cut with an underwater cutter to obtain spherical polymer particles. Subsequently, the obtained polymer particles are pneumatically transported through a pneumatic transportation pipe to be stirred and crystallized (Be)
pex company formula), crystallize the polymer particle surface at 150 ° C., transfer to a stationary solid-state polymerization tower, and dry at about 140 ° C. for 3 hours under a nitrogen flow of 20 l / kg · hr. Solid phase polymerization was performed at 210 ° C. for 20 hours to produce a polyethylene terephthalate resin as spherical particles.

The obtained resin particles had a = 3.2 mm, b = 3.4 mm, c =
It was 3.3 mm, the average particle size was 3.3 mm, the maximum particle size was 1.03 times the average particle size, and the minimum particle size was 0.96 times the average particle size. These resin particles were pneumatically transported through a pneumatic transport pipe made of low-density polyethylene (manufactured by Nippon Polychem Co., Ltd., "UE320") over a length of 1 m, and transferred to a silo. . The resulting polyethylene terephthalate resin composition was prepared by converting low density polyethylene to 14 pp.
b, and its intrinsic viscosity was 0.76 dl / g.

From the obtained polyethylene terephthalate resin composition, an injection molding machine (M-70, manufactured by Meiki Seisakusho)
A)), the temperature of each part of the cylinder and the nozzle head 2
80 ° C., screw rotation speed 200 rpm, injection time 60
Secondly, each stepped plate-shaped molded plate having a thickness of 4 mm and 5 mm was injection molded at a mold cooling water temperature of 10 ° C. With respect to the obtained molded plate, the crystallization temperature and the transparency of the resin composition were measured, and the results are shown in Table 1. In addition, the measuring method of each physical property is as follows.

Crystallization temperature Differential scanning calorimeter (manufactured by Seiko Electronics Co., Ltd., “DSC220
C)), using a 5 mm thick portion of the molded plate, the temperature was raised from room temperature to 285 ° C. at a rate of 20 ° C./min, and the top temperature of the crystallization peak observed in the middle (heating crystallization) Temperature: TC ₁ ) was measured, and the temperature was further increased. When the temperature reached 285 ° C., the temperature was maintained for 3 minutes, and then the temperature was lowered at a rate of 10 ° C./min. (Cold crystallization temperature: TC ₂ ) was measured. Transparency haze meter (NDH-300A, manufactured by Nippon Denshoku)
, The haze was measured for portions having a thickness of 4 mm and 5 mm of the molded plate.

Further, from the obtained polyethylene terephthalate resin composition, an injection molding machine (manufactured by Nissei ASB Machine Co., Ltd.)
"ASB-50TH"), cylinder temperature 285
° C, screw rotation speed 100 rpm, primary injection pressure 14
0 kg / cm ² , secondary injection pressure 40 kg / cm ² , mold temperature 20 ° C., injection holding pressure time 14 seconds, cooling time 10 seconds,
The preform is injection-molded, and the preform is stretch-blow-molded by a blow molding machine set at a blow pressure of 15 to 30 kg / cm ² , a mold temperature of 160 ° C., and a molding cycle of 15 seconds. A bottle having an internal volume of about 1.5 liter was formed. The appearance of the obtained bottle was visually observed and evaluated according to the following criteria. ；: Transparent without turbidity and without deformation. Δ: Transparent without turbidity, but deformed. ×: Whitening during crystallization.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the produced polymer was drawn out in a strand form from a discharge port provided at the bottom of the polycondensation tank, cooled with water, and then cut with a cutter to obtain elliptic cylindrical polymer particles. Thus, polyethylene terephthalate resin particles were produced. The obtained resin particles were in the shape of an elliptic cylinder having a major axis of 3.2 mm, a minor axis of 2.7 mm, and a length of 3 mm. When the resin particles were transferred to a silo in the same manner as in Example 1, the obtained polyethylene terephthalate resin composition contained 4 ppb of low-density polyethylene and had an intrinsic viscosity of 0.76 dl / g. Further, injection molding was carried out in the same manner as in Example 1, and each physical property was measured. The results are shown in Table 1.

[0028]

[Table 1]

[0029]

According to the present invention, it is possible to provide a method for producing a polyethylene terephthalate resin composition having an improved crystallization rate by lowering the crystallization temperature without lowering the transparency.

Claims (7)

[Claims] An average particle diameter is 1 to 6 mm, and
The maximum particle size is 1.2 times or less the average particle size, the minimum particle size is 0.8 times or more the average particle size, spherical particles of polyethylene terephthalate resin, under flow conditions, different from the resin A method for producing a polyethylene terephthalate resin composition, which comprises bringing a polyethylene terephthalate resin composition into contact with a member made of a crystalline thermoplastic resin to contain a small amount of the crystalline thermoplastic resin, followed by melt-kneading to form a polyethylene terephthalate resin composition. 2. The method for producing a polyethylene terephthalate resin composition according to claim 1, wherein the member made of the crystalline thermoplastic resin is a pipe for pneumatic transportation of the polyethylene terephthalate resin particles. 3. The method for producing a polyethylene terephthalate resin composition according to claim 1, wherein the member made of the crystalline thermoplastic resin is a rod-like or net-like body provided on a transport path of the polyethylene terephthalate resin particles. 4. The method for producing a polyethylene terephthalate resin composition according to claim 1, wherein the crystalline thermoplastic resin is a polyolefin resin. 5. The method for producing a polyethylene terephthalate resin composition according to claim 4, wherein the polyolefin resin is a polyethylene resin. 6. The method for producing a polyethylene terephthalate resin composition according to claim 4, wherein the polyolefin resin is a polypropylene resin. 7. The method for producing a polyethylene terephthalate resin composition according to claim 1, wherein the temperature-rise crystallization temperature of the resin composition formed into a molded body is in the range of 145 to 170 ° C.