JPH09143349A - Polyester resin composition and film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin compsn. which crystallizes at a rate high enough and can be formed into a film by inflation or by T-die extrusion without causing fusion or blocking by compounding a polyester resin with a specific mannitol compd. as a nucleating agent. SOLUTION: A polyester resin is compounded with a mannitol compd. represented by the formula (wherein R<1> to R<6> are each H, a 1-5C alkyl, or acyl) pref. in an amt. of 0.1-5wt.% of the resin. The resin is not specifically limited and may be an arom. one such as polyethylene terephthalate or an aliph. one such as polyethylene adipate. An example of the compd. is a mannitol (deriv.) and may be of a D-, L-, or DL-form. Since the compd. is biodegradable, the use of biodegradable polyester resin (e.g. polyethylene succinate) is advantageous. The compsn. is excellent in moldability, does not exhibit the degradation in strengths and appearance, and is suitable for packaging materials and miscellaneous goods for daily use because of its biodegradability.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester resin composition and a film.

[0002]

BACKGROUND OF THE INVENTION Polyester, a crystalline thermoplastic, is widely used in various applications because of its excellent mechanical properties. However, polyester is
Since the crystallization speed is slow, there is a drawback that the moldability is poor.

Therefore, various crystal nucleating agents have been added in order to improve the crystallization rate of polyester. As a conventionally known crystal nucleating agent, for example, JP-A-7-126
496 publication, specifically, Zn powder,
Inorganic simple substance such as Al powder, graphite, carbon black; ZnO, MgO, Al ₂ O ₃ , TiO ₂ , MnO ₂ , S
Metal oxides such as iO ₂ and Fe ₃ O ₄ ; nitrides such as aluminum nitride, silicon nitride, titanium nitride and boron nitride; Na
₂ CO ₃ , CaCO ₃ , MgCO ₃ , CaSO ₄ , CaSi
Inorganic salts such as O ₃ , BaSO ₄ , Ca ₃ (PO ₄ ) ₃ ; clays such as talc, kaolin, clay and clay; calcium oxalate, sodium oxalate, calcium benzoate, calcium phthalate, calcium tartrate, stearin Organic salts such as magnesium acid salts and polyacrylic acid salts; polymer compounds such as polyester, polyethylene and polypropylene.

However, since the inorganic substances such as the simple substance, metal oxides, nitrides, inorganic salts, and clays described above have poor dispersibility in the polyester resin, when they are used as the crystal nucleating agent, However, there is a problem in that the mechanical strength and the appearance are deteriorated.

Further, when an organic salt is used as a crystal nucleating agent, there is a problem that the metal contained therein accelerates the deterioration of the polyester resin.

Further, when a polymer compound is used as a crystal nucleating agent, there is a problem that the crystallization rate is not sufficiently improved.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the crystal nucleating agent, and is excellent in forming a film by inflation molding or T-die molding. The present invention provides a polyester resin composition that can be easily molded and processed without causing problems such as fusion to a winding roll, fusion between films, and blocking, and a film formed by molding the resin composition. That is the purpose.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a novel crystal nucleating agent in order to solve the problems found in the known crystal nucleating agents, and as a result, the mannites are polyester. It was found that it is effective in improving the crystallization rate of. That is, it was found that a polyester resin composition obtained by blending mannitol with polyester has a high crystallization rate and excellent moldability.

That is, the present invention relates to polyester (a)
And the following general formula (1)

[0010]

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(In the formulae, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom or a carbon number of 1 to 1).
5 represents an alkyl group or an acyl group. ) Is a polyester resin composition containing mannites represented by the formula (1).

It is preferable that the polyester (a) is an aliphatic polyester because the biodegradability is improved.

Another aspect of the present invention is a film formed by molding the polyester resin composition.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester (a) used in the present invention is not particularly limited, and examples thereof include those obtained by polycondensation of terephthalic acid with a diol such as ethylene glycol or 1,4-butanediol. Aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyethylene succinates, polybutylene succinates and polyethylene adipates, which are polyesters of diols such as ethylene glycol and 1,4-butanediol and aliphatic dicarboxylic acids And aliphatic polyesters such as polybutylene adipate; and polyesters such as polylactic acid and polyglycolic acid, which are polyesters of hydroxycarboxylic acids.

The polyester (a) of the present invention is used in a polyester resin composition, and the specific production method thereof is not particularly limited, but for the aliphatic polyester, there are the following production methods, for example.

(I) Polybasic acid (or ester thereof)
(Ii) Polycondensation of hydroxycarboxylic acid (or ester thereof) (iii) Ring-opening polymerization of cyclic acid anhydride and cyclic ether (iv) Ring-opening polymerization of cyclic ester Among the methods for obtaining such an aliphatic polyester (a), as a method that can be industrially efficiently produced in a relatively short time, a step including ring-opening polymerization of a cyclic acid anhydride and a cyclic ether of (iii) is performed. The method having is preferred. The ring-opening polymerization of cyclic acid anhydride and cyclic ether will be described in more detail below.

As the cyclic acid anhydride used in the method (iii), for example, succinic anhydride, maleic anhydride,
Examples thereof include itaconic anhydride, glutaric anhydride, adipic anhydride, citraconic anhydride and the like. Examples of the cyclic ether include ethylene oxide, propylene oxide,
Cyclohexene oxide, styrene oxide, epichlorohydrin, allyl glycidyl ether, phenyl glycidyl ether, tetrahydrofuran, oxepane,
1,3-dioxolane and the like can be mentioned.

Of these, a combination of succinic anhydride and ethylene oxide is preferable in view of the melting point, biodegradability and economy of the polyester obtained.

By sequentially adding cyclic ethers to cyclic acid anhydrides in the presence of a polymerization catalyst, polyesters obtained by substantially ring-opening copolymerization of acid anhydrides and cyclic ethers can be obtained in a short time. It can be manufactured.

The mannitol used in the present invention is not particularly limited as long as it is a compound represented by the general formula (1), and mannitol or some of the six hydroxyl groups of mannitol are alkyl groups. Examples thereof include compounds etherified or substituted with an acyl group. The mannite used in the present invention may be any of D-form, L-form and DL-form.

Mannites are compounds used in food additives and have good microbial degradability, and therefore have the effect of improving the biodegradability of the polyester resin composition as compared with other crystal nucleating agents. Have. Furthermore, when a polyester having biodegradability such as polyethylene succinate obtained by ring-opening copolymerization of succinic anhydride and ethylene oxide is used as the polyester (a), the biodegradability of the polyester resin composition is improved. preferable.

The amount of the mannite compounded is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polyester (a). If it is less than 0.01 part by weight, the effect as a crystal nucleating agent is not sufficient, and if it is more than 10 parts by weight, it is economically disadvantageous.

There is no particular limitation on the method of blending the mannitols with the polyester (a). For example, a method of melt-kneading the polyester and the mannites in a twin-screw extruder, or a method of dissolving them in a suitable solvent is used. There is a method of mixing.

The polyester resin composition of the present invention may further contain the above-mentioned conventionally known crystal nucleating agent. If necessary, other components such as pigments, dyes, heat resistance agents, antioxidants, weather resistance agents, lubricants, antistatic agents, stabilizers, fillers, reinforcing materials, flame retardants, plasticizers, other polymers, etc. Can be added within a range that does not impair the effects of the present invention.

The method for film-forming the polyester resin composition of the present invention is not particularly limited, and known methods can be used. Examples include inflation molding and the T-die method.

The film according to the present invention is not particularly limited in its thickness, and includes a generally-known film having a thickness of less than 0.25 mm and a sheet having a thickness of 0.25 mm or more.

The crystallization rate of polyester can be determined from the half width of the exothermic peak in the slow cooling crystallization process by DSC measurement. That is, it can be said that the narrower the full width at half maximum of the exothermic peak measured at the cooling rate of 3 ° C./min is, the faster the crystallization rate is.

This DSC measurement can be carried out by an ordinary method using a commercially available device, for example, SSC5200 type manufactured by Seiko Denshi Kogyo Co., Ltd. For example, about 20 mg of a sample is heated in the nitrogen atmosphere to a temperature equal to or higher than the melting point of polyester to be completely melted, then cooled at a predetermined rate, and an exothermic peak associated with crystallization is recorded.

When the DSC measurement is performed on the aliphatic polyester in this manner, an exothermic peak due to crystallization appears in the range of 10 to 200 ° C. at a cooling rate of 3 ° C./min. However, this exothermic peak is usually extremely broad, and the half-value width of the peak is usually about 25 ° C. when the crystal nucleating agent is not added. A wide range of aliphatic polyester is slow to crystallize and a good molded product cannot be obtained.

Further, conventional crystal nucleating agents have problems that the crystallization rate is insufficiently improved and the appearance of the molded product is deteriorated.

On the other hand, in the polyester resin composition of the present invention, the exothermic peak due to crystallization in the cooling process of DSC measurement shifts to the high temperature side at a cooling rate of 3 ° C./min and reaches a half value. The width is an exothermic peak with an extremely narrow acute angle of 15 ° C. or less.

[0032]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. Parts in the examples are parts by weight unless otherwise specified.

The melting point of the polyester resin composition, the crystallization temperature, and the half-width of the exothermic peak were measured using DSC (Seiko Denshi Kogyo's SSC5200 model) in a nitrogen atmosphere. After heating to the above to completely melt it, it is rapidly cooled to -50 ° C, then heated at a rate of 6 ° C / min, and the endothermic peak at this time is measured to obtain the melting point.
The crystallization temperature and the full width at half maximum were obtained by cooling at a rate of / min and recording the exothermic peak associated with crystallization.

The number average molecular weight of polyester is the polystyrene equivalent molecular weight determined by GPC.

Reference Example 1 (Synthesis of Polyester) 500.0 parts of succinic anhydride and 4.9 parts of zirconyl octylate were added to an autoclave, and the atmosphere was replaced with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C with stirring to melt the succinic anhydride, and 231.1 parts of ethylene oxide was added while maintaining the pressure in the autoclave at 4.0 to 8.5 kgf / cm2 at the same temperature. Was introduced continuously at a rate of 58 parts per hour for 4 hours. After the introduction of ethylene oxide, aging reaction was carried out at 130 ° C for 1 hour, and then the system was returned to room temperature to give a number average molecular weight of 13,000, D
A polymerization product having a melting point of 101.2 ° C. by SC was obtained.

70.0 parts of the obtained polymerization product was used as a self-cleaning twin-screw kneader (S1KR manufactured by Kurimoto Iron Works Co., Ltd.).
C reactor, inner diameter 25 mm, L / D = 10.2) in a nitrogen stream under reduced pressure of 1-2 mmHg, 100 rpm, jacket temperature 240 ° C. for 4 hours to give a number average molecular weight of 63,000. Polyester (1) was synthesized.

Example 1 100 parts of the polyester (1) synthesized in Reference Example 1 was mixed with D
5 parts of mannitol at 170 ° C. using a twin-screw kneader
After kneading for a minute, a polyester resin composition (2) was obtained.

The melting point, crystallization temperature and full width at half maximum of the polyester resin composition (2) determined by DSC measurement were 101.4 ° C., 71.7 ° C. and 10.6 ° C., respectively.

Obtained polyester resin composition (2)
Was melted at 110 ° C. and inflation-molded. At the time of molding, a good film was able to be obtained without fusion to a winding roll or blocking between films.

The obtained film was embedded in a soil-filled planter and taken out 100 days later, the film was ragged, and weight loss was observed.
Biodegradability was observed.

Comparative Example 1 The melting point, crystallization temperature, and half-value width of the polyester (1) synthesized in Reference Example 1 were 10 and 10 respectively.
It was 1.1 ° C., 33.6 ° C. and 24.3 ° C., the crystallization rate was slow, and inflation molding could not be performed.

Comparative Example 2 100 parts of the polyester (1) synthesized in Reference Example 1 was kneaded with 1 part of calcium oxalate at 170 ° C. for 5 minutes using a biaxial kneader to obtain a polyester resin composition (3). It was

The melting point, crystallization temperature and full width at half maximum of the polyester resin composition (3) determined by DSC measurement were 100.2 ° C., 56.1 ° C. and 21.2 ° C., respectively.

The polyester resin composition (3) thus obtained had a slow crystallization rate and could not be formed into a film.

[0045]

EFFECTS OF THE INVENTION The polyester resin composition of the present invention has a high crystallization rate and excellent moldability, and is well formed during film formation by inflation molding or T-die molding, and is fused to a winding roll. In addition, it is possible to easily perform the molding process without causing problems such as fusion between the films and blocking.

Further, the film of the present invention does not cause problems such as deterioration of mechanical strength of resin and deterioration of appearance. Further, a film using an aliphatic polyester as the polyester (a) is excellent in biodegradability and can be suitably used as a disposable packaging material or daily sundries.

The resin composition and the film of the present invention can be suitably used for moldings, fibers, packaging materials and the like.

[Brief description of the drawings]

1 is a DSC chart of the polyester resin composition (2) obtained in Example 1. FIG. The analysis results for the measurement of the half width of the exothermic peak are also shown.

Claims (4)

[Claims] 1. A polyester (a) having the following general formula (1): (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom, or an alkyl group or an acyl group having 1 to 5 carbon atoms). A polyester resin composition containing knits. 2. The polyester resin composition according to claim 1, wherein the polyester (a) is an aliphatic polyester. 3. The polyester resin composition according to claim 1 or 2, wherein the polyester (a) is obtained by a process including ring-opening polymerization of a cyclic acid anhydride and a cyclic ether. 4. A film formed by molding the polyester resin composition according to any one of claims 1 to 3.