JPH1077397A - Polyester composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester composition, excellent in toughness and impact resistance with time and usable for applications of metallic laminates in containers for foods and beverages by melt mixing a specific polyethylene terephthalate with a specified polytetramethylene terephthalate. SOLUTION: This polyester composition comprises (A) 60-98 pts.wt. of polyethylene terephthalate composed of (i) >=70mol% of terephthalic acid as an acid component and (ii) ethylene glycol as a diol component and (B) 2-40 pts.wt. of polytetramethylene terephthalate composed of 70-95mol% of the component (i) and (ii) 5-30mol% of a 6-12C aliphatic dicarboxylic acid as an acid component and (iv) tetramethylene glycol as a diol component. At least 1% of bonds contained in only the polyester of either of the components A and B is exchanged with bonds contained in the other polyester. Thereby, the resultant composition is excellent in toughness at ambient temperature and low temperatures and is suitable for metallic laminates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition comprising a structural unit mainly composed of ethylene terephthalate, which is rich in toughness and a metal laminating composition.

[0002]

2. Description of the Related Art Polyesters comprising a constitutional unit mainly composed of ethylene terephthalate are widely used in the fields of fibers, films and resins because of their easy moldability. However, when used for thin-walled products, it is preferable that the crystallinity is low, and in the case of a polyester having high crystallinity, for example, polyethylene terephthalate in which the acid component is only terephthalic acid, crystallization occurs at high temperature conditions and the impact strength is reduced. There are drawbacks. For this reason, for film applications, for example, polyesters having reduced crystallinity and imparted flexibility, ie, polyethylene terephthalate copolymerized with an isophthalic acid component, have been proposed. However, polyethylene terephthalate copolymerized with isophthalic acid still has a high glass transition point, and thus has insufficient toughness at low temperature and room temperature.

[0003]

An object of the present invention is to provide a polyester composition having excellent toughness at room temperature and low temperature. Another object of the present invention is to provide a polyester composition having a level of impact resistance over time and a polyester composition for metal lamination that can be particularly suitably used for metal lamination, particularly for metal lamination of food and beverage containers. Is to provide.

[0004]

The present inventors have conducted intensive studies and found that the impact resistance of a polyester composition, particularly the impact resistance over time in a state of being laminated on a metal, is as high as that of polyethylene terephthalate and C6. To 12 depending on the internal structure of the polyester composition produced by melt-kneading with polytetramethylene terephthalate having an aliphatic dicarboxylic acid as a copolymer component, i.e., formed by a transesterification reaction with the polyester constituting the composition. It is found that it depends on the existing ratio of the bond
It has been found that when the transesterification ratio is 1% or more, high impact resistance is achieved, and in particular, sufficient temporal impact resistance as a polyester composition for metal lamination is achieved. The present invention is based on the above findings.

That is, according to the present invention, 60 to 98 parts by weight of polyethylene terephthalate (A) having terephthalic acid of 70 mol% or more as an acid component and ethylene glycol as a diol component, 70 to 95 mol% of terephthalic acid and 6 to 12 carbon atoms.
A polyester composition comprising 2 to 40 parts by weight of a polytetramethylene terephthalate (B) comprising 5 to 30 mol% of an aliphatic dicarboxylic acid as an acid component and tetramethylene glycol as a diol component; A polyester composition characterized in that at least 1% of the bonds contained in only one polyester of methylene terephthalate (B) are exchanged for the bonds contained in the other polyester.

The present invention has a main feature in the internal structure of the polymer constituting the composition. The present invention can be described as follows when expressed as a composition. That is, terephthalic acid 70 mol%
60 to 98 parts by weight of polyethylene terephthalate (A) containing the above as an acid component and ethylene glycol as a diol component, 70 to 95 mol% of terephthalic acid, and 6-1 carbon atoms.
2) a polyester composition comprising 2 to 40 parts by weight of polytetramethylene terephthalate (B) comprising 5 to 30 mol% of an aliphatic dicarboxylic acid as an acid component and tetramethylene glycol as a diol component; At least 1 part by weight of a block copolymer (C) of polyethylene terephthalate (A) and polytetramethylene terephthalate (B) is contained per 100 parts by weight of tetramethylene terephthalate (B) in total, and has a melting point in the range of 220 ° C to 250 ° C. It is a polyester composition which shows these.

Hereinafter, the present invention will be described in detail. The polyethylene terephthalate (A) used in the present invention is a polyethylene terephthalate comprising 70 mol% or more of terephthalic acid and 30 mol% or less of a copolymer component as a dicarboxylic acid component and ethylene glycol as a diol component. The copolymerization component is preferably an aromatic dicarboxylic acid, for example, isophthalic acid, phthalic acid; methyl terephthalic acid,
Alkyl-substituted phthalic acids such as methyl isophthalic acid.

[0008] The proportion of the copolymer component is preferably 5 to 30 mol%. When the amount of the copolymer component is 5 to 30 mol%, sufficient mechanical strength can be obtained together with high impact resistance. The diol component constituting the polyethylene glycol (A) is mainly ethylene glycol, but other diols such as aliphatic diols having 2 to 12 carbon atoms and alicyclic diols such as cyclohexanedimethanol may be used as the copolymer component. Frequently, the proportion of this copolymer component is less than 30 mol%, preferably less than 20 mol%, based on the total diol component. When the amount of the copolymer component is less than 30 mol%, the characteristics of polyethylene terephthalate are maintained.

The polytetramethylene terephthalate (B) used in the present invention comprises 70 to 95 mol% of terephthalic acid and 5 to 30 mol% of a copolymer component as a dicarboxylic acid component.
Polytetramethylene terephthalate comprising tetramethylene glycol as a diol component. The copolymer component is an aliphatic dicarboxylic acid having 6 to 12 carbon atoms, preferably adipic acid and sebacic acid.

As the copolymerization component, other aliphatic dicarboxylic acids and aromatic dicarboxylic acids can be used instead of the aliphatic dicarboxylic acids having 6 to 12 carbon atoms. This is when the aliphatic dicarboxylic acids of Formulas 6 to 12 are used. The aromatic dicarboxylic acid is, for example, an alkyl-substituted phthalic acid such as isophthalic acid and phthalic acid; methyl terephthalic acid and methyl isophthalic acid. The proportion of the copolymer component is 5 to 30 mol% of the total dicarboxylic acid component.

Polytetramethylene terephthalate (B)
Is mainly tetramethylene glycol, but other diols such as aliphatic diols having 2 to 12 carbon atoms and alicyclic diols such as cyclohexanedimethanol may be copolymerized. The proportion is less than 30 mol%, preferably 20 mol%, based on all diol components.
Is less than. Within this range, the characteristics of polytetramethylene terephthalate are maintained.

In the polyester composition of the present invention, the amounts of polyethylene terephthalate (A) and polytetramethylene terephthalate (B) before the melt mixing are determined by adding polyethylene terephthalate (A) and polytetramethylene terephthalate (B). Per 100 parts by weight, polyethylene terephthalate (A) is 60 to 98 parts by weight and polytetramethylene terephthalate (B) is 2 to 40 parts by weight.

[0013] The polyethylene terephthalate (A) is 60
When the content is up to 98 parts by weight, the inherent properties of polyethylene terephthalate are retained as a composition and high toughness is exhibited.

The polyethylene terephthalate (A) and the polytetramethylene terephthalate (B) are present in the same ratio even after melt mixing.

According to the present invention, at least one of the bonds contained in only one polyester of polyethylene terephthalate (A) or polytetramethylene terephthalate (B) is used.
% Is a polyester composition characterized in that it exchanges for a bond contained in the other polyester, the main feature being this internal structure.

However, when expressed as a composition from a different point of view, the polyester composition of the present invention contains terephthalic acid 7
Polyethylene terephthalate (A) 60 containing 0 mol% or more as an acid component and ethylene glycol as a diol component
Polytetramethylene terephthalate (B) 2 to 40, which comprises -98 parts by weight, 70-95 mol% of terephthalic acid and 5-30 mol% of an aliphatic dicarboxylic acid having 6-12 carbon atoms as an acid component and tetramethylene glycol as a diol component. Polyester composition comprising polyethylene terephthalate (A) and polytetramethylene terephthalate (B) per 100 parts by weight in total of polyethylene terephthalate (A) and polytetramethylene terephthalate (B). Is a polyester composition containing at least 1 part by weight of a polyester and having a melting point in the range of 220 ° C to 250 ° C.

In the present invention, the block copolymer (C) is formed by melt mixing polyethylene terephthalate (A) and polytetramethylene terephthalate (B).

In other words, the ratio of the exchange of bonds inside the composition, in other words, the amount of the block copolymer can be confirmed by the following method. That is, an ester bond between dicarboxylic acid constituting polyethylene terephthalate (A) and tetramethylene glycol constituting polyethylene tetramethylene terephthalate (B), a dicarboxylic acid component constituting polyethylene terephthalate (A), and polyethylene terephthalate were determined by ¹ H-NMR. It can be confirmed by the ratio of the ester bond with ethylene glycol constituting (A) in the composition.

When the rate of exchange of bonds is 1% or more, the composition of the present invention exhibits sufficient stretchability, impact properties and high toughness. It is presumed that this is because the dispersion state of polytetramethylene terephthalate in the polyethylene terephthalate (A) is improved.

The polyester used in the present invention has a temperature of 35 ° C.
The intrinsic viscosity measured in orthochlorophenol is 0.3 or more, preferably 0.4 to 1.2 for polyethylene terephthalate (A), and 0.6 or more, preferably 0.6 for polytetramethylene terephthalate (B). ~ 1.2. This range is preferable in terms of mechanical strength.

The polyester composition of the present invention is kept in water at 50 ° C. for 24 hours in a state of being laminated with a steel sheet, and then JI is applied to the surface on which the polyester composition is laminated.
Based on the impact deformation test of SK5400, a weight of 200 g was dropped from a position of 20 cm in height and collided with the weight, and then the collision position was impregnated with 1% saline and a voltage of 6 V was applied. The impact resistance over time defined as a current value (mA) is preferably 0.2 mA or less, more preferably 0.05 mA or less, and particularly preferably less than 0.01 mA.

The polyethylene terephthalate (A) itself and the polytetramethylene terephthalate (B) itself can be produced by a conventionally known melt polycondensation reaction or a method combining this with a solid phase polymerization reaction.

Such a polyester composition is prepared by preparing polyethylene terephthalate (A) and polytetramethylene terephthalate (B) in advance, respectively, and forming a bond contained in only one polyester of polyethylene terephthalate (A) or polytetramethylene terephthalate (B). It can be produced by transesterification until at least 1% exchanges for the bonds contained in the other polyester.

This transesterification reaction is carried out at 270-295.
° C, preferably at a temperature of 280-295 ° C for 15 minutes ~
1.5 hours, polyethylene terephthalate (A)
And polytetramethylene terephthalate (B).

The melting point of the polyester composition resulting from the melt mixing is in the range of 220 ° C. to 250 ° C.

In the present specification, the melting point is 20 ° C./mi measured by a scanning differential calorimeter (DSC: manufactured by TA Instrument).
n is a value calculated from the peak of the chart by measurement under a nitrogen stream.

As for the melting point, when the content of the polyester copolymer is sufficiently large, the melting point measured by DSC is observed as one peak. This is considered to be because polyethylene terephthalate (A) and polytetramethylene terephthalate (B) are easily compatible with each other due to the presence of the polyester copolymer.

Melt mixing can be performed in an extruder by dry blending. When the transesterification reaction is performed in an extruder by dry blending, at least 270 to 295 ° C., preferably 280 to 295 ° C., at least 280 to 295 ° C. by melt-kneading under the conditions of kneading for 3 to 30 minutes. 1% by weight of the block copolymer can be obtained.

If necessary, additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, inorganic particles, organic particles, and an antistatic agent are dispersed and compounded in the polyester copolymer composition of the present invention. can do.

The polyester composition of the present invention is rich in toughness and high in impact strength, so that it can be used for food containers and packaging materials, etc., and because it has excellent adhesion to metal plates, it is suitable for metal lamination applications. It can be particularly suitably used as a food / beverage container laminate material made of a metal-laminated steel plate.

The polyester copolymer composition of the present invention is particularly preferably used as an organic coating agent for side seamless cans (side seamless cans). As described above, the polyester composition of the present invention has a property of high toughness and high impact strength, and this property is retained even in a state of being laminated on a steel sheet, and further has a high impact resistance over time in a state of being laminated on a steel sheet. It is.

The composition of the present invention can be formed into a sheet shape and used as an unstretched sheet or a stretched sheet, and can be used after being laminated on a steel sheet.

As a laminating method, a method of laminating the polyester copolymer composition of the present invention on a steel sheet by a T-die extrusion lamination method can be used. Lamination can also be performed by multi-layer lamination by co-extrusion or by a method in which each layer is separately melt-extruded and laminated into multiple layers. In this case, the polyester composition of the present invention can be used for the layer directly in contact with the metal plate, polyethylene terephthalate for the second layer, and polyethylene terephthalate (A) shown in the present invention for the third layer. Examples of the metal plate on which the polyester copolymer composition of the present invention is laminated include tinplate, tin-free steel, aluminum and the like. As a bonding method, there can be mentioned a method in which a polyester composition melted from a T-die is flowed down onto a preheated metal plate, bonded, cooled, and adhered.

[0034]

The present invention will be described in detail with reference to examples. In the examples, “parts” means “parts by weight”. The characteristics were measured by the following methods.

[Tensile Impact Test] ASTM D-1822
[Impact resistance test over time] A single-layer unstretched film is laminated on a steel plate so that the resin layer to be evaluated is on the side in contact with the metal plate. Lamination is performed by laminating the unstretched film on a 210 μm-thick steel plate which has been subjected to electrolytic chromic acid treatment, and using a hot press at 285 ° C., a pressure of 20 kg / min.
It was laminated with a steel plate by holding at a pressure of cm ² for 30 seconds. It is kept in water at 50 ° C. for 24 hours after production. Then, JIS K54
The impact deformation test is performed according to the method described in No. 00. That is, a shooting die having a radius of curvature of 5 mm is set on the upper surface of the laminated plate on which the film is not laminated, and a weight having a mass of 200 g is gravity-dropped on the shooting die from a position having a height of 20 cm. At this time, a thickness of 5 m is placed under the laminate plate.
Prepare a rubber plate of m. After being subjected to the impact deformation test, one electrode was applied to a metal surface of the laminate plate on which the film was not laminated, and 1% salt was applied to the film surface of the other laminate plate at the position where the weight fell (convex portion). A cotton soaked with water is applied and the other electrode is applied to the cotton. A voltage of 6 V is applied, and the current value at that time is measured.
The smaller the current value (mA), the better the impact resistance with time.

[Measurement of Ester Exchange Rate] The exchange rate between polyethylene terephthalate (A) and polytetramethylene terephthalate (B) was measured using ¹ H-NMR at 600 MHz. The details are as follows. Hereinafter, polyethylene terephthalate (A) is referred to as component (A), and polytetramethylene terephthalate (B) is referred to as component (B).

Focusing on the ester bond composed of the aliphatic dicarboxylic acid and tetramethylene glycol as the component (B),
The peak intensity of H in tetramethylene glycol closest to the above-mentioned ester bond when ¹ H-NMR of the composition in the example obtained by melt-mixing the components (A) and (B) was (1 ). On the other hand, when the components (A) and (B) are melt-mixed and transesterified, H in ethylene glycol closest to an ester bond based on an ester bond composed of an aliphatic dicarboxylic acid and ethylene glycol is newly added.
Are observed, and the transesterification rate can be determined from each peak intensity ((2) / ((1) + (2))) × 100. In addition, transesterification occurs not only at the ester bond of the aliphatic dicarboxylic acid moiety but also at the ester bond of the aromatic dicarboxylic acid moiety. The origin exchange rate is determined as the copolymer formation rate. The peak intensity is determined from the integral ratio of H derived from a site near the ester bond of each diol.

[Examples 1 to 4 and Comparative Examples 1 and 2] Table 1
The polyester (intrinsic viscosity 0.70) copolymerized with the components shown in (1) is dried at 130 ° C., melt-kneaded at 280 ° C. for 5 minutes using an extruder, melt-extruded from a slit die, and cast roller. To obtain an undrawn film. The thickness of the obtained film is 1
It was 00 μm. A dumbbell piece was punched out from the MD direction of the obtained film and used as a test piece.
The tensile impact test was performed at% RH.

Example 1 In Example 1, 60 parts by weight of polyethylene terephthalate copolymerized with 10 mol% of isophthalic acid as the component (A) and polybutylene copolymerized with 10 mol% of adipic acid as the component (B) An unstretched film was obtained by the above method using 40 parts by weight of terephthalate. The transesterification rate measured by the above method was 3%. Table 2 shows the results of the tensile impact test.

Example 2 In Example 2, 75 parts by weight of polyethylene terephthalate copolymerized with 10 mol% of isophthalic acid as the component (A) and polybutylene copolymerized with 10 mol% of adipic acid as the component (B) An unstretched film was obtained in the same manner as in Example 1 using 25 parts by weight of terephthalate. The transesterification rate was 3%.

Example 3 In Example 3, 60 parts by weight of polyethylene terephthalate in which 15 mol% of isophthalic acid was copolymerized as the component (A) and polybutylene in which 15 mol% of adipic acid was copolymerized as the component (B) An unstretched film was obtained in the same manner as in Example 1 using 40 parts by weight of terephthalate. The transesterification rate was 2%.

Example 4 In Example 4, 75 parts by weight of polyethylene terephthalate in which 15 mol% of isophthalic acid was copolymerized as the component (A) and polybutylene in which 15 mol% of adipic acid was copolymerized as the component (B) An unstretched film was obtained in the same manner as in Example 1 using 25 parts by weight of terephthalate. The transesterification rate was 2%.

Comparative Example 1 In Comparative Example 1, the component (A), isophthalic acid 10 mol% copolymerized polyethylene terephthalate, was used alone. An unstretched film was obtained in the same manner as in Example 1.

Comparative Example 2 In Comparative Example 2, 60 parts by weight of polyethylene terephthalate obtained by copolymerizing 15% by mole of isophthalic acid as the component (A) and 40 parts of polybutylene terephthalate containing no copolymerized component as the component (B) were used. Parts by weight were used. An unstretched film was obtained in the same manner as in Example 1. The transesterification rate was 2%.

Comparative Example 3 In Comparative Example 3, the components (A) and (B) used in Example 3 were used in the same ratio.
Melt kneading conditions with an extruder were set at a temperature of 280 ° C,
An unstretched film was obtained in the same manner as in Example 1 except that the melt kneading time was 1 minute. The transesterification rate was 0.5%. The results are summarized in Tables 1 and 2.

[0046]

[Table 1]

[0047]

[Table 2]

Examples 1 to 4 are examples in which adipic acid is used as a copolymerization component of the component (B). These compositions have high impact resistance. Further, when the transesterification rate is low as shown in Comparative Example 3, only a low impact strength can be obtained despite the fact that it is composed of the same polyester component as in Example 4.

[Examples 5 and 6 and Comparative Examples 4, 5, 6] [Example 5] In Example 5, the unstretched film obtained in Example 1 was subjected to the aging resistance test according to the aging resistance test described above. The impact properties were measured.

[Example 6] In Example 6, the unstretched film obtained in Example 2 was used to measure impact resistance over time in the same manner as in Example 5.

Comparative Example 4 In Comparative Example 4, the unstretched film obtained in Comparative Example 1 was used to measure the impact resistance over time in the same manner as in Example 5.

[Comparative Example 5] In Comparative Example 5, the unstretched film obtained in Comparative Example 2 was used to measure impact resistance over time in the same manner as in Example 5.

Comparative Example 6 In Comparative Example 6, the unstretched film obtained in Comparative Example 3 was used, and the impact resistance with time was measured in the same manner as in Example 5. The results are summarized in Table 3.

[0054]

[Table 3]

Examples 5 and 6 were all Comparative Examples 4, 5, and 6.
Was better.

[0056]

The polyester composition of the present invention is excellent in toughness and impact resistance over time. Therefore, it is suitable for use in cans for food and beverage containers, especially as an organic coating agent for sideless seamless cans when laminated on a metal plate. Can be used.

Claims (4)

[Claims] 1. An acid component comprising at least 70 mol% of terephthalic acid.
60 to 98 parts by weight of polyethylene terephthalate (A) containing ethylene glycol as a diol component, 70 to 95 mol% of terephthalic acid and 5 to 30 mol% of an aliphatic dicarboxylic acid having 6 to 12 carbon atoms as an acid component, and tetramethylene glycol as a diol A polyester composition comprising 2 to 40 parts by weight of polytetramethylene terephthalate (B) as a component, wherein at least 1% of the bonds contained in only one of polyethylene terephthalate (A) and polytetramethylene terephthalate (B) are included. A polyester composition characterized by being exchanged for a bond contained in the other polyester. 2. An acid component comprising at least 70 mol% of terephthalic acid,
60 to 98 parts by weight of polyethylene terephthalate (A) containing ethylene glycol as a diol component, 70 to 95 mol% of terephthalic acid and 5 to 30 mol% of an aliphatic dicarboxylic acid having 6 to 12 carbon atoms as an acid component, and tetramethylene glycol as a diol A polyester composition comprising 2 to 40 parts by weight of polytetramethylene terephthalate (B) as a component, wherein the total amount of polyethylene terephthalate (A) and polytetramethylene terephthalate (B) is 100.
The composition contains at least 1 part by weight of a block copolymer (C) of polyethylene terephthalate (A) and polytetramethylene terephthalate (B) per part by weight,
A polyester composition having a melting point in the range of 0 ° C. 3. The polyester composition for a metal laminate according to claim 1 or 2. 4. An acid component comprising at least 70 mol% of terephthalic acid.
60 to 98 parts by weight of polyethylene terephthalate (A) containing ethylene glycol as a diol component, 70 to 95 mol% of terephthalic acid and 5 to 30 mol% of an aliphatic dicarboxylic acid having 6 to 12 carbon atoms as an acid component, and tetramethylene glycol as a diol A polyester composition comprising 2 to 40 parts by weight of polytetramethylene terephthalate (B) as a component is melt-kneaded at a temperature of 270 ° C to 295 ° C for 1 to 30 minutes, and a polyester composition having a melting point in the range of 220 ° C to 250 ° C. A method for producing a polyester composition for metal lamination, characterized by obtaining a product.