CN118043374A - Resin, resin composition, and molded article - Google Patents

Abstract

A resin comprising polybutylene succinate and having an alkali metal content of 0.001 to 6.0 mass ppm. According to the present invention, there can be provided a polyester resin, a resin composition and a molded article which have both of seawater biodegradability and hydrolysis resistance, which are opposite properties, at a high level.

Description

Resin, resin composition, and molded article

Technical Field

The present invention relates to a resin, a resin composition, and a molded body.

Background

In modern society, plastics are widely used in daily applications such as packaging materials, home electric appliance materials, and building materials because of their light weight and excellent electrical insulation properties, molding processability, and durability. As plastics used for these applications, there are polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and the like.

However, these molded plastic articles are difficult to decompose in natural environments, and therefore remain in the ground even after use. In addition, even if burned, harmful gas may be generated to damage the incinerator.

Therefore, biodegradable plastics that are easily decomposed in composting and the like have been actively developed. As a plastic exhibiting biodegradability, for example, a copolymer polymer of 3-hydroxybutyric acid and 3-hydroxycaproic acid (PHBH) and the like are known (patent document 1).

Patent document 2 discloses a copolymer having a specific viscosity obtained by condensing a specific amount of succinic acid, a C2 to C8 dicarboxylic acid, 1, 3-propanediol, or 1, 4-butanediol. And discloses that the copolymer disclosed in patent document 2 is a polybutylene succinate (PBS) -based copolymer, and has good mechanical properties and improved biodegradability relative to PBS.

Prior art literature

Patent literature

Patent document 1: WO2013/147139

Patent document 2: japanese patent application laid-open No. 2012-504167

Disclosure of Invention

In recent years, marine pollution caused by waste plastics in the ocean has become a great social problem. Therefore, when a plastic having high marine biodegradability is developed, it is expected to solve the problem of marine pollution caused by the plastic. However, the above biodegradable plastics are mainly focused on the biodegradation in compost, and there has been no sufficient study on plastics having high decomposability in seawater with a small amount of decomposing bacteria.

On the other hand, when plastics are used, it is generally required that the plastics are not easily degraded, and it is preferable that the hydrolysis resistance be high. Therefore, in practice, it is desired to develop a plastic having both biodegradability and hydrolysis resistance, but since biodegradability and hydrolysis resistance are properties opposite to each other in terms of decomposition of the plastic, it is considered that it is difficult to develop a plastic having both properties.

Patent document 1 discloses a biodegradable plastic that is easily decomposed in composting or the like, that is, a copolymer polymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid (PHBH), but does not disclose or suggest more difficult biodegradation in the ocean.

In addition, patent document 2 discloses a copolymer of a PBS-based polymer, and also discloses polybutylene succinate (PBSSe). However, the biodegradability evaluation in patent document 2 is an evaluation in compost soil, and the biodegradability in the ocean is not evaluated.

The present application has an object to provide a resin, a resin composition and a molded article which have both of seawater biodegradability and hydrolysis resistance, which are opposite properties, at a high level.

The present inventors have conducted intensive studies in view of the above-described actual circumstances. As a result, it was found that impurities in a resin composed of polybutylene succinate (hereinafter, sometimes referred to as "PBSSe") as a biodegradable polyester affect biodegradability and hydrolysis resistance. That is, the present invention has been completed by controlling the content of specific impurities in PBSSe to solve the above-described problems.

The gist of the present invention is as follows.

[1] A resin comprising polybutylene succinate and having an alkali metal content of 0.001 to 6.0 mass ppm.

[2] The resin according to the above [1], wherein a ratio (S/Se) of the number of groups derived from sebacic acid to the number of groups derived from succinic acid constituting the above polybutylene succinate is in a range of 71/29 to 95/5.

[3] The resin according to the above [1], wherein a ratio (S/Se) of the number of groups derived from sebacic acid to the number of groups derived from succinic acid constituting the above polybutylene succinate is in a range of 71/29 to 89/11.

[4] The resin according to any one of the above [1] to [3], wherein an acid value is 50eq/t or less.

[5] The resin according to any one of the above [1] to [4], wherein the content of sulfur atoms is 4.0 mass ppm or less.

[6] The resin according to any one of the above [1] to [5], wherein the weight average molecular weight is 10000 ～ 2500000.

[7] The resin according to any one of the above [1] to [6], wherein the reduced viscosity at 30℃is 0.5dl/g to 4.0dl/g.

[8] A resin composition comprising the resin according to any one of the above [1] to [7 ].

[9] A molded article comprising the resin according to any one of [1] to [7 ].

According to the present invention, a resin composition, and a molded article having both of seawater biodegradability and hydrolysis resistance, which are opposite properties, at a high level can be provided.

Detailed Description

Embodiments of the present invention are described in detail below. The present invention is not limited to the following description, and may be modified and implemented arbitrarily within a range not departing from the gist of the present invention. In the present specification, "to" is used in the sense that it includes values before and after the numerical value or the physical property value is added to the numerical value.

[ Resin ]

An embodiment of the present invention is a resin comprising polybutylene succinate and having an alkali metal content of 0.001 to 6.0 mass ppm. The alkali metal is usually contained as an impurity in polybutylene succinate and the content of the alkali metal is 0.001 to 6.0 mass ppm, whereby the biodegradability of seawater can be improved while maintaining hydrolysis resistance.

The seawater biodegradability and hydrolysis resistance are considered to be in an inverse relationship in terms of the degradability of the polyester. It is also known that the hydrolysis resistance of polyesters is reduced when the content of alkali metal or sulfur atoms is large or when the acid value is high (non-patent document 1 and patent documents 2 to 8). Accordingly, the present inventors have studied and have intended to improve the biodegradability of seawater by increasing the amount of alkali metal. However, it is unexpected that the biodegradability of seawater can be improved and the hydrolyzability also suppressed by decreasing the content of alkali metal instead. Alkali metals are generally considered to have an effect of promoting hydrolysis. In such knowledge, it can be said that the small alkali metal content promotes the decomposition of the seawater biological decomposition, which is an unexpected significant effect.

Non-patent document 1: saturated polyester Manual (Shang Mu and Man's editions, japanese Industrial News, first edition release 12/22/1989), patent document 2: japanese patent laid-open No. 63-225623, patent document 3: japanese patent laid-open No. 56-81334, patent document 4: japanese patent No. 4380704, patent document 5: japanese patent application laid-open No. 2002-206058 and patent document 6: japanese patent publication 2012-505171, patent document 7: japanese patent laid-open publication No. 2011-208008, patent document 8: japanese patent application 2012-149176

Polybutylene succinate (PBSSe) >

PBSSe is a polyester obtained by polycondensation of 1, 4-butanediol as a diol and a mixed acid of succinic acid or an alkyl ester thereof (hereinafter, both may be referred to as "succinic acid component") and sebacic acid or an alkyl ester thereof (hereinafter, both may be referred to as "sebacic acid component") as a dicarboxylic acid or an alkyl ester thereof (hereinafter, both may be referred to as "dicarboxylic acid component"). That is, PBSSe is a polyester having a group derived from 1, 4-butanediol (1, 4-butanediol unit), a group derived from a succinic acid component (succinic acid unit), and a group derived from a sebacic acid component (sebacic acid unit).

The ratio (S/Se, molar ratio) of the number of groups derived from the succinic acid component to the number of groups derived from the sebacic acid component constituting PBSSe of the present invention is preferably a large number of groups derived from the sebacic acid component from the viewpoint of reducing the crystallinity of PBSSe and accelerating the biodegradation rate. On the other hand, from the viewpoint of easily obtaining heat resistance and hydrolysis resistance, it is preferable that the succinic acid component has a large number of groups. That is, if the S/Se (molar ratio) is within a specific range, the balance between the biodegradability of seawater and hydrolysis resistance becomes good.

Specifically, S/Se (molar ratio) is preferably 71/29 or more, more preferably 74/26 or more, still more preferably 76/24 or more, and particularly preferably 81/19 or more. On the other hand, the ratio is preferably 95/5 or less, more preferably 89/11 or less. That is, S/Se (molar ratio) is preferably 71/29 to 95/5, more preferably 71/29 to 89/11, still more preferably 74/26 to 89/11, still more preferably 76/24 to 89/11, particularly preferably 81/19 to 89/11.

The dicarboxylic acid unit PBSSe is composed of the succinic acid unit and the sebacic acid unit as described above, but may have a small amount of other dicarboxylic acid units as long as the effect of the present invention is not impaired. Specifically, the other dicarboxylic acid units are preferably 10 mol% or less, more preferably 5 mol% or less, and still more preferably 1 mol% or less, relative to the total dicarboxylic acids. The lower limit is not particularly limited, and may be 0 mol% (excluding other dicarboxylic acids).

(Alkali metals)

In the PBSSe of the present invention, it is important that the content of alkali metal (metal conversion) is 0.001 to 6.0 mass ppm. By setting the content of alkali metal to 6.0 mass ppm or less, resins having both seawater biodegradability and hydrolysis resistance at high levels can be produced. From the above viewpoints, the content of the alkali metal is preferably 3.0 mass ppm or less, more preferably 2.0 mass ppm or less. The lower the alkali metal content, the better, but from the standpoint of low purification cost, the alkali metal content is 0.001 mass ppm or more. The alkali metal content was measured by the method described in the examples.

Examples of the alkali metal include lithium, sodium, and potassium. Among these, sodium and potassium are easily mixed as impurities, and sodium is most easily mixed. Therefore, it is considered that reducing the content of the sodium that is easily mixed is effective for providing both the seawater biodegradability and the hydrolysis resistance.

The main mixing route of the alkali metal is considered to be derived from the raw material, and when the raw material derived from the biomass is used, the raw material may be mixed from any of 1, 4-butanediol, succinic acid component, and sebacic acid component, but is considered to be mainly derived from the sebacic acid component. Therefore, as a method for reducing the content of alkali metal such as sodium, a method for reducing the content of alkali metal in the sebacic acid component by purification of the sebacic acid component or the like is considered to be preferable.

The amount of the alkali metal contained in the raw material sebacic acid component is preferably 30 mass ppm or less, more preferably 10 mass ppm or less, further preferably 5 mass ppm or less, and particularly preferably 1 mass ppm or less. The amount of alkali metal contained in the raw material sebacic acid component is preferably as low as possible, but is usually 0.001 mass ppm or more in view of low cost for raw material purification and the like.

The content of the alkali metal contained in PBSSe of the present invention can be reduced by purifying the polymerized resin.

(Sulfur atom)

From the viewpoint of having both biodegradability and hydrolysis resistance of seawater, it is preferable that the sulfur atom content in PBSSe is also small. Specifically, the sulfur atom content in PBSSe is preferably 4.0 mass ppm or less. By setting the sulfur atom content to 4.0 mass ppm or less, resins having both seawater biodegradability and hydrolysis resistance at high levels can be produced. From the above viewpoints, the content of sulfur atoms is preferably 3.0 mass ppm or less, more preferably 2.0 mass ppm or less, and particularly preferably 1.0 mass ppm or less. The lower limit is not particularly limited as the content of sulfur atoms is lower, but is usually 0.001 mass ppm or more in view of low purification cost. The content of sulfur atoms can be measured by the method described in examples.

Sulfur atoms are incorporated as impurities PBSSe. The main mixing route of sulfur atoms is considered to be derived from a raw material, and when a raw material derived from a biomass is used, the mixing of the raw material from any of 1, 4-butanediol, succinic acid component and sebacic acid component is considered to be possible, but the main mixing route is considered to be derived from sebacic acid component. Therefore, as a method for reducing the content of sulfur atoms, a method of reducing the content of sulfur atoms in a sebacic acid component by purification of the sebacic acid component or the like is considered to be preferable.

The amount of sulfur atoms contained in the raw material sebacic acid component is preferably 30 mass ppm or less, more preferably 10 mass ppm or less, further preferably 5 mass ppm or less, and particularly preferably 1 mass ppm or less. The amount of sulfur atoms contained in the raw material sebacic acid component is preferably as low as possible, but is usually 0.001 mass ppm or more in view of low cost for raw material purification and the like.

< PBSSe Properties >

(Acid value)

In the present invention, the Acid Value (AV; acid Value) of PBSSe is preferably 50eq/t or less. From the viewpoint of easily improving the biodegradability of seawater while maintaining hydrolysis resistance, it is preferable that the acid value of PBSSe of the present invention is low. Therefore, it is more preferably 40eq/t or less, and still more preferably 30eq/t or less.

The lower limit of the acid value of PBSSe is preferably 0.1eq/t or more, more preferably 1eq/t or more, from the viewpoint of manufacturing cost and the like. The lower the acid number of PBSSe the fewer the carboxylic acid ends from the unreacted dicarboxylic acid component, the higher the acid number of PBSSe the more the carboxylic acid ends. Therefore, the polymerization conditions and the like can be used for adjustment. It is also considered that the type or amount of impurities in the raw material such as nitrogen compounds and metal ions can be adjusted.

As described above, by changing the conditions such as the polymerization temperature and the polymerization time, the acid value of PBSSe can be controlled by suppressing the types and amounts of impurities, and PBSSe having a desired acid value can be obtained.

The acid value can be measured by the method described in examples.

(Glass transition temperature (Tg))

When PBSSe is subjected to biodegradation, it is considered that the molecular main chain can be rotated and vibrated to facilitate the biodegradation by making the glass transition temperature lower than the environmental temperature in which the resin such as seawater is present. Therefore, the glass transition temperature (Tg) of PBSSe according to the present invention is preferably 40℃or lower, more preferably 30℃or lower, further preferably 25℃or lower, particularly preferably 20℃or lower. The glass transition temperature PBSSe can be measured by a thermal analysis method.

(Reduced viscosity)

The reduced viscosity of PBSSe may be appropriately selected according to the application, processing method, and the like. The reduced viscosity ηsp/c at 30℃of PBSSe is preferably 0.5dL/g or more, more preferably 0.8dL/g or more, still more preferably 1.0dL/g or more, particularly preferably 1.2dL/g or more. On the other hand, the ratio is preferably 4.0dL/g or less, more preferably 3.0dL/g or less, still more preferably 2.5dL/g or less, and particularly preferably 2.3dL/g or less.

By setting the reduced viscosity of PBSSe to the above range, mechanical properties can be ensured at the time of processing into a molded article, and the melt viscosity of the biodegradable resin composition at the time of molding processing can be set to a level at which excessive load is not imposed on molding machines such as an extruder and an injection machine, thereby ensuring productivity.

The reduced viscosity of PBSSe can be measured by the method described in examples.

(Molecular weight)

The molecular weight of PBSSe is typically determined using Gel Permeation Chromatography (GPC). From the viewpoints of moldability and mechanical strength, the weight average molecular weight (Mw) of PBSSe based on monodisperse polystyrene is preferably in the following range. That is, the weight average molecular weight (Mw) is preferably 10000 or more, more preferably 20000 or more, further preferably 30000 or more, and particularly preferably 50000 or more. On the other hand, it is preferably 2500000 or less, more preferably 1000000 or less, further preferably 800000 or less, particularly preferably 600000 or less, even more preferably 500000 or less, and most preferably 400000 or less.

(Melt flow Rate (MFR))

The Melt Flow Rate (MFR) of PBSSe can be evaluated by a value measured at 190℃under a load of 2.16kg based on JIS K7210 (1999).

From the viewpoints of moldability and mechanical strength, the MFR of PBSSe is preferably in the following range. That is, it is preferably 0.1g/10 min or more, more preferably 1g/10 min or more. Further, on the other hand, PBSSe has an MFR of preferably 100g/10 min or less, more preferably 80g/10 min or less, still more preferably 50g/10 min or less, particularly preferably 40g/10 min or less, and most preferably 30g/10 min or less. The MFR of the resin may be adjusted by the molecular weight or the like.

(Melting point)

From the viewpoint of moldability, the melting point of PBSSe is preferably in the following range. That is, the melting point of PBSSe is preferably 60℃or higher, more preferably 70℃or higher, still more preferably 75℃or higher, particularly preferably 80℃or higher. On the other hand, the temperature is preferably 270℃or lower, more preferably 200℃or lower, further preferably 160℃or lower, particularly preferably 150℃or lower, even more preferably 140℃or lower, and most preferably 130℃or lower. When PBSSe has a plurality of melting points, at least one melting point may be within the above range.

(Tensile modulus)

From the viewpoints of molding processability and impact resistance, the tensile modulus of PBSSe is preferably in the following range. That is, it is preferably 10MPa or more, more preferably 100MPa or more, and still more preferably 180MPa or more. On the other hand, the pressure is preferably 2500MPa or less, more preferably 2000MPa or less.

The tensile modulus of PBSSe can be determined by the following method.

The test piece was produced by producing PBSSe hot pressed pieces and punching the hot pressed pieces into No.8 dumbbell pieces. Specifically, a metal frame subjected to surface mold release treatment was placed on a 150mm×150mm PTFE sheet, 1.6g PBSSe was weighed and collected inside the metal frame, and a 150mm×150mm PTFE sheet was further placed thereon. The hot pressed sheet was hot pressed by a hot press and then cold pressed by a cold press with PBSSe sandwiched between 2 iron plates (160 mm. Times.160 mm, 3mm in thickness) to obtain a hot pressed sheet of 70 mm. Times.70 mm. Times.0.1 mm in thickness. The hot pressing temperature is 200 ℃, the hot pressing time is 2 minutes of preheating and 2 minutes of pressing. In addition, the cold pressing temperature was 20℃and the cold pressing time was 2 minutes. The hot pressed sheet was uniaxially stretched at a speed of 50mm/min, and the initial slope of the obtained stress-strain curve was determined as a tensile modulus.

The method for adjusting the melting point and tensile modulus of PBSSe is not particularly limited. For example, the copolymerization ratio of the copolymerization components can be adjusted.

[ Resin composition ]

The resin composition according to the present embodiment is a resin composition containing PBSSe as a main component. The main component in the resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. The total amount (100 mass%) of the resin may be PBSSe.

< Other Components >

The resin composition according to the present embodiment may contain various additives and the like as long as the effects of the present invention are not significantly impaired.

[ Method for producing PBSSe ]

As a method for producing PBSSe, a known method related to the production of polyester can be used. In this case, the polycondensation reaction may be set to a proper condition used conventionally, and is not particularly limited. In general, a method of further increasing the polymerization degree by performing a depressurizing operation after the esterification reaction is performed is employed.

Specifically, 1, 4-butanediol, a succinic acid component, and a sebacic acid component are mixed so as to be S/Se as required, heated under nitrogen with stirring, then heated while reducing the pressure, and reacted at a constant temperature for a constant time. In general, the diol and the dicarboxylic acid component are substantially reacted in equimolar amounts, but since a part of the diol is distilled off in the esterification reaction, the diol is generally used in an amount of 1 to 30 mol% more than the dicarboxylic acid component.

The polymer obtained by the reaction is preferably extruded in a strand form into water and cut to obtain PBSSe in the form of pellets.

The molar ratio (S/Se) of the unit derived from the succinic acid component to the unit derived from the sebacic acid component of PBSSe can be determined by ¹ H-NMR (nuclear magnetic resonance spectroscopy).

< Raw materials >

The 1, 4-butanediol, succinic acid component and sebacic acid component as raw materials may be derived from petroleum or from plants, but from the viewpoint of environmental friendliness, plants are preferable. In particular, sebacic acid is known to be derived from castor oil, preferably sebacic acid from plants.

Among them, in general, the amount of impurities in plant-derived raw materials is large, purification cost is high, and high purity products are large and multivalent. Here, as described above, since it is known that the hydrolysis resistance of polyesters is reduced when the content of alkali metal or sulfur atoms is large or when the acid value is high, it is considered that low-cost low-purity products are generally preferable to obtain polyesters having high biodegradability.

However, in PBSSe of the present invention, as described above, it is important that the content of alkali metal as an impurity is rather reduced, so that a raw material having a higher degree of purification and a small amount of impurity is preferably used.

The purification method is not particularly limited as long as the content of alkali metal in the raw material such as sebacic acid can be reduced, and conventionally known methods can be used. Specifically, there are methods such as distillation, extraction, and crystallization, but from the viewpoint of simplicity and high efficiency, crystallization is preferable.

In addition, as a raw material for manufacturing PBSSe, a small amount of a polyfunctional compound may be used. Specific examples of the polyfunctional compound include trifunctional or higher polyhydric alcohols, trifunctional or higher polycarboxylic acids and/or anhydrides thereof, and trifunctional or higher hydroxycarboxylic acids. The polyfunctional compound may be used alone or in any combination and ratio.

Examples of the trifunctional or higher polyol include glycerin, trimethylolpropane, pentaerythritol, and the like.

Examples of the trifunctional or higher polycarboxylic acid or anhydride thereof include propane tricarboxylic acid, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, and cyclopentane tetracarboxylic anhydride.

Examples of the trifunctional or higher hydroxycarboxylic acid include malic acid, hydroxyglutaric acid, hydroxymethylglutaric acid, tartaric acid, citric acid, hydroxyisophthalic acid, and hydroxyterephthalic acid. Among these, malic acid, tartaric acid, citric acid, and mixtures thereof are preferable from the viewpoint of ease of obtaining.

From the viewpoint of less tendency to gel, the amount of the polyfunctional compound used is preferably small. Specifically, the amount of the monomer unit is usually 5 mol% or less, preferably 1 mol% or less, more preferably 0.50 mol% or less, and particularly preferably 0.3 mol% or less, based on 100 mol% of all the monomer units constituting the polyester. On the other hand, the amount used is usually 0.0001 mol% or more, preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and particularly preferably 0.01 mol% or more, from the viewpoint of easiness in producing PBSSe having a high polymerization degree.

Catalyst

PBSSe are typically manufactured in the presence of a catalyst. As the catalyst, a catalyst usable in the production of a known polyester resin can be arbitrarily selected as long as the effect of the present invention is not significantly impaired. As examples thereof, metal compounds such as germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, zinc and the like are preferable. Among them, germanium compounds and titanium compounds are more preferable. The catalyst may be used alone in 1 kind, or two or more kinds may be used in any combination and ratio. In addition, as long as the object of the present invention is not impaired, catalysts other than these may be used in combination.

Examples of the germanium compound that can be used as the catalyst include organic germanium compounds such as tetraalkoxy germanium, and inorganic germanium compounds such as germanium oxide and germanium chloride. Among them, germanium oxide, tetraethoxy germanium, tetrabutoxy germanium or the like is preferable from the viewpoints of price, ease of obtaining and the like, and germanium oxide is more preferable.

Examples of the titanium compound that can be used as the catalyst include organic titanium compounds such as tetraalkoxytitanium, e.g., tetrapropyl titanate, tetrabutyl titanate, tetraphenyl titanate, and the like. Among them, tetrapropyl titanate and tetrabutyl titanate are preferable from the viewpoints of price, ease of acquisition, and the like.

The amount of the catalyst used is arbitrary as long as the effect of the present invention is not significantly impaired, and is usually 0.0005 mass% or more, preferably 0.001 mass% or more, relative to the amount of the monomer used. On the other hand, the content is usually 3% by mass or less, preferably 1.5% by mass or less. When the amount of the catalyst is within the above range, the production cost can be suppressed, a sufficient catalyst effect can be obtained, and the resulting polymer can be suppressed in the deterioration of the coloration and hydrolysis resistance, and can exhibit high seawater biodegradability.

The catalyst may be introduced at the time of the introduction of the raw material or at the time of the start of the depressurization, without any particular limitation, as long as it is before the polycondensation reaction.

The metal in the catalyst may be contained in PBSSe as an impurity. From the viewpoints of biodegradability and hydrolysis resistance of seawater, it is preferable that the content of the metal derived from the catalyst in PBSSe is also small. Specifically, the content of the metal derived from the catalyst contained in PBSSe is preferably 200 mass ppm or less, more preferably 100 mass ppm or less, further preferably 70 mass ppm or less, and particularly preferably 50 mass ppm or less. The lower limit is not particularly limited, but is usually 0.001 mass ppm or more. In particular, the content of magnesium in PBSSe is preferably in the above-described range. The content of magnesium atoms can be measured by the method described in examples.

< Reaction Condition >

The reaction conditions such as temperature, polymerization time, and pressure at the time of esterification reaction and/or transesterification reaction of the dicarboxylic acid component with the diol are arbitrary as long as the effects of the present invention are not significantly impaired. The reaction temperature of the esterification reaction and/or transesterification reaction of the dicarboxylic acid component with the diol is usually 150℃or higher, preferably 180℃or higher, usually 260℃or lower, preferably 250℃or lower. The reaction atmosphere is usually an inert atmosphere such as nitrogen or argon. The reaction pressure is usually from normal pressure to 10kPa, with normal pressure being preferred. The reaction time is usually 1 hour or more, usually 10 hours or less, preferably 6 hours or less, and more preferably 4 hours or less. By setting the reaction conditions within the above-described range, gelation caused by excessive formation of unsaturated bonds can be suppressed, and the degree of polymerization can be controlled.

The pressure of the esterification reaction and/or the polycondensation reaction after the transesterification reaction of the dicarboxylic acid component with the diol is usually 0.01X10 ³ Pa or more, preferably 0.03X10 ³ Pa or more, usually 1.4X10 ³ Pa or less, preferably 0.4X10 ³ Pa or less. The reaction temperature in this case is usually 150℃or higher, preferably 180℃or higher, and usually 260℃or lower, preferably 250℃or lower. The reaction time is usually 2 hours or more, usually 15 hours or less, preferably 10 hours or less. By setting the reaction conditions within the above-described range, gelation caused by excessive formation of unsaturated bonds can be suppressed, and the degree of polymerization can be controlled.

< Chain extender >)

In the production PBSSe, a chain extender such as a carbonate compound or a diisocyanate compound may be used. When a chain extender is used, it is preferable not to use the chain extender, and it is preferable to use a small amount of the chain extender from the viewpoint of ensuring the biodegradability because it may affect the biodegradability by introducing different types of bonds such as carbonate bonds and urethane bonds into the chain.

The amount of the chain extender used is usually 10 mol% or less, preferably 5 mol% or less, and more preferably 3 mol% or less, based on the total ratio of the carbonate bonds and the urethane bonds constituting all the structural units of PBSSe. From the viewpoint of biodegradability of PBSSe, the carbonate bond is preferably less than 1 mol%, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less, relative to the total structural units constituting PBSSe. The urethane bond is preferably 0.55 mol% or less, more preferably 0.3 mol% or less, further preferably 0.12 mol% or less, and particularly preferably 0.05 mol% or less. The amount is preferably 0.9 mass% or less, more preferably 0.5 mass% or less, further preferably 0.2 mass% or less, particularly preferably 0.1 mass% or less, based on PBSSe mass%. In particular, when the amount of the urethane bond is in the above range, smoke and odor generated by decomposition of the urethane bond can be suppressed in the film forming step or the like, and film breakage due to foaming in the molten film can be suppressed, so that molding stability can be ensured. The amount of carbonate bonds or urethane bonds in the polyester resin can be calculated from the measurement results by NMR (nuclear magnetic resonance spectroscopy) methods such as ¹ H-NMR method and ¹³ C-NMR method.

Specific examples of the carbonate compound which is a chain extender include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-tolyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, dipentyl carbonate, dicyclohexyl carbonate and the like. In addition, a carbonate compound derived from a hydroxyl compound such as phenols or alcohols may be used.

Specific examples of the diisocyanate compound include known diisocyanates such as 2, 4-toluene diisocyanate, a mixture of 2, 4-toluene diisocyanate and 2, 6-toluene diisocyanate, 1, 5-naphthalene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4 '-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, 2,4, 6-triisopropylphenyl diisocyanate, 4' -diphenylmethane diisocyanate, and tolidine diisocyanate.

In addition, as other chain extenders, two can be usedOxazolines, silicate esters, and the like.

Specific examples of the silicate include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

[ Method for producing resin composition ]

The method for producing the resin composition according to the present embodiment is not particularly limited. The resin composition according to the present embodiment can be obtained by kneading PBSSe, another resin, an additive, and the like.

[ Molded article ]

The molded article of the resin and the resin composition according to the present embodiment can be obtained by molding the resin or the resin composition according to the present embodiment by various molding methods used for general-purpose plastics.

The molded article of the resin and the resin composition according to the present embodiment can be suitably used for a wide range of applications such as packaging materials for packaging various foods, medicines, liquid materials such as sundries, powder and granular materials, solid materials, agricultural materials, and building materials. Specific applications include injection molded articles (for example, trays for fresh foods, containers for snack foods, containers for coffee capsules, tableware, outdoor leisure goods, etc.), extrusion molded articles (for example, films, sheets, fish lines, fishing nets, vegetation nets, secondary processing sheets, water-retaining sheets, etc.), blow molded articles (bottles, etc.), and the like. Examples of the material include films for agricultural use, coating materials, fertilizer coating materials, nursery pots, laminated films, plates, stretched sheets, monofilaments, nonwoven fabrics, flat filaments, staple fibers, crimped fibers, striped tapes, split yarns, composite fibers, blow-molded bottles, shopping bags, garbage bags, compost bags, cosmetic containers, cleaning agent containers, bleach containers, ropes, bundling materials, sanitary coating materials, cold boxes, buffer material films, multifilament yarns, synthetic papers, medical surgical threads, sutures, artificial bones, artificial skins, DDS (Drug DELIVERY SYSTEM: drug delivery system) such as microcapsules, wound coating materials, and the like. The molded article is particularly suitable for use as a food packaging film, a tray for fresh food, a container for snack food, a container for food such as a lunch box, or the like.

Examples

Hereinafter, the content of the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to the following examples as long as the gist thereof is not exceeded. The values of various production conditions or evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and preferable ranges may be ranges defined by combinations of the values of the upper limit or the lower limit and the values of the following examples or the values of the examples each other.

Method for measuring content

(Metal element)

Measured by high frequency inductively coupled plasma emission spectrometry. The sample was subjected to wet decomposition and then to constant volume, and the alkali metal content was measured by ICP-AES (manufactured by Thermo FISHER SCIENTIFIC company, "iCAP7600 Duo").

(Sulfur atom)

Measured by ion chromatography. The sample was burned by a combustion absorber (Nittoseiko Analytech, AQF 2100H) and sulfate ions in the absorption liquid in which the generated gas was absorbed were measured by an ion chromatograph (Thermo FISHER SCIENTIFIC, dionex ICS1600, column AS 12A).

Method for measuring physical Properties

(Acid value (AV))

Accurately weighing PBSSe g of 0.4g, adding 25mL of benzyl alcohol thereto, heating to 195℃and stirring to dissolve. After PBSSe was dissolved, the container containing PBSSe solution was cooled with an ice bath, and 2mL of ethanol was added to the container. Titration was performed using an automatic titration apparatus "GT200" manufactured by Mitsubishi CHEMICAL ANALYTECH, using a benzyl alcohol solution of 0.01N sodium hydroxide (the amount to be titrated is set as A (ml)).

Next, the same measurement was carried out with benzyl alcohol alone as a blank value (B (ml)). The acid value (equivalent per 1 ton) was calculated from the following formula.

Acid value (eq/t) = (A-B) ×F×10/W

A (ml): measuring the amount of dripping

B (ml): blank drop quantity

F: coefficient of 0.01N NaOH benzyl alcohol standard solution

W (g): sample mass

(Reduced viscosity)

PBSSe was dissolved in phenol and tetrachloroethane at a ratio of 0.5g/dL 1:1 (mass ratio) in a mixed solvent, to prepare a resin solution. Next, the passage time of the resin solution at 30℃was measured using an Ubbelohde viscosity tube, and the reduced viscosity (. Eta. _sp/c unit; dl/g) was calculated based on the result.

(Reduced viscosity retention)

PBSSe pellets obtained by cutting the resin extruded in a strand form were allowed to stand at a constant temperature and humidity of 40℃and a relative humidity of 90% RH for 29 days. Reduced viscosity before and after the constant temperature and humidity treatment was measured and substituted into the following formula (1) to calculate the reduced viscosity retention rate. The closer to 100% the reduced viscosity retention, the better the hydrolysis resistance of the resin.

The reduced viscosity retention rate in comparative example 1 was a predicted value calculated based on the initial viscosity, since the reduced viscosity before the treatment was unknown.

< Biodegradability test >)

The biological decomposition degree is calculated as the ratio of Biological Oxygen Demand (BOD) to theoretical oxygen demand (ThOD). Specifically, regarding biological decomposition in seawater, ISO 14851 is based on: 1999 (determination of the final aerobic biological decomposition ability of the material in the plastic-aqueous medium-determination by means of the method for determining the carbon dioxide released).

Into a 510mL brown bottle containing 30mg of a sample, 100mL of a mixture of a standard test culture medium adjusted by a method based on ISO 14851 and seawater was added. A pressure sensor (OxiTop (registered trademark) -type C, manufactured by WTW) was attached to a brown bottle, and the test solution was stirred with a stirrer at 25℃for 19 days, and the biological degradation (%) was calculated based on the BOD measurement. Expressed in the table as seawater biodegradability.

The biodegradability test of example 1 and comparative example 1 was evaluated using the same sea water on the same day, and the biodegradability test of example 2 and comparative example 2 was evaluated using sea water collected on a different day from that of example 1. Therefore, the results of example 1 and comparative example 1 can be directly compared, and the results of example 2 and comparative example 2 can be directly compared.

Example 1 >

< PBSSe manufacture >)

43.0 Parts by mass of succinic acid, 9.0 parts by mass of sebacic acid, 48.0 parts by mass of 1, 4-butanediol, and 0.10 parts by mass of trimethylolpropane are charged into a reaction vessel equipped with a stirring device, a nitrogen inlet, a heating device, a thermometer, and a pressure reducing port. The sebacic acid used herein contained 0.94 mass ppm of sodium atom and 0.68 mass ppm of sulfur atom. In addition, the molar ratio of succinic acid/sebacic acid was 89/11.

While stirring the contents of the reaction vessel, nitrogen gas was introduced into the vessel, and the inside of the system was placed under a nitrogen atmosphere by reduced pressure substitution. Next, the contents of the reaction vessel were stirred, and then heated from 160 ℃ to 230 ℃ over 1 hour, and reacted at 230 ℃ for 1 hour. Thereafter, tetrabutyl titanate in an amount of 70 mass ppm in terms of titanium atoms and magnesium acetate in an amount of 33 mass ppm in terms of magnesium atoms were added to the obtained polyester, and the pressure was reduced to 0.07×10 ³ Pa or less over 1.5 hours. Further, after 30 minutes from the start of the depressurization, the temperature was raised to 250℃over 30 minutes, and the polycondensation was continued while maintaining the heated and depressurized state. The polymerization was ended at a time of 2 hours and 20 minutes after reaching 250℃to give PBSSe.

The acid value of PBSSe obtained was 23eq/t, the reduced viscosity was 1.86dL/g, the reduced viscosity retention was 91%, and the biodegradability was 19%. The molar ratio of the succinic acid-derived unit to the sebacic acid-derived unit of PBSSe as determined by ¹ H-NMR (nuclear magnetic resonance spectroscopy) was 89/11. The PBSSe thus obtained contained 1.5 mass ppm of sodium atoms, less than 0.7 mass ppm of sulfur atoms, and 40 mass ppm of magnesium atoms. The results of these analyses are shown in Table 1.

Example 2 >

PBSSe was produced in the same manner as in example 1, except that the reaction time after reaching 250℃in example 1 was set to 2 hours and 43 minutes. The reduced viscosity of PBSSe was 2.19dL/g, the reduced viscosity retention was 88%, and the biodegradability was 11%. The obtained PBSSe contained 2.0 mass ppm of sodium atom, less than 0.7 mass ppm of sulfur atom, and 40 mass ppm of magnesium atom. The alkali metal only detected sodium. The results of these analyses are shown in Table 1.

Comparative example 1 ]

PBSSe was produced in the same manner as in example 1 except that in example 1, trimethylolpropane was added in an amount of 0.237 parts by mass, and sebacic acid containing 41 ppm by mass of sodium atoms and 32 ppm by mass of sulfur atoms was used.

The acid value of PBSSe obtained was 47eq/t and the degree of biological decomposition was 10%. The obtained PBSSe contained 8.3 mass ppm of sodium atoms and 4.7 mass ppm of sulfur atoms. The results of these analyses are shown in Table 1.

Comparative example 2]

PBSSe was produced in the same manner as in comparative example 1, except that sebacic acid containing 52 mass ppm of sodium atoms and 37 mass ppm of sulfur atoms was used in example 1.

The acid value of PBSSe obtained was 33eq/t, the reduced viscosity was 3.41dL/g, the reduced viscosity retention was 88%, and the biodegradability was 7%. The obtained PBSSe contained 9.5 mass ppm of sodium atoms and 5.4 mass ppm of sulfur atoms. The results of these analyses are shown in Table 1.

TABLE 1

In table 1, it is clear from a comparison between example 1 and comparative example 1 that PBSSe of comparative example 1 having a large content of sodium atoms has low biodegradability of seawater. On the other hand, PBSSe of example 1 had high values for reduced viscosity retention and biodegradability of seawater.

In addition, the same results were also shown in the comparison of example 2 and comparative example 2, which were measured using seawater different from the sampling date of example 1 and comparative example 1, and the seawater biodegradability of PBSSe of comparative example 2, which contains a large amount of sodium atoms, was low, whereas the reduced viscosity retention rate and the seawater biodegradability of PBSSe of example 2 were both high values.

Further, the reduced viscosity retention rates of PBSSe in examples 1,2 and comparative example 2 were high regardless of the content of sodium atoms. In contrast, the PBSSe of examples 1 and 2 having a sodium atom content of 6.0 mass ppm or less had high values of reduced viscosity retention and biodegradability of seawater.

Industrial applicability

The resin and the resin composition comprising polybutylene succinate and sebacate of the invention are resins having both seawater biodegradability and hydrolysis resistance which are opposite in performance, and resin compositions using the resins. Therefore, the molded article obtained from the resin and the resin composition of the present invention is less likely to deteriorate in use and has high hydrolysis resistance. On the other hand, since the biodegradability is high, it can be decomposed by microorganisms or the like after use, and in particular, even when thrown into the ocean, the seawater biodegradability is high, and thus it is a resin and resin composition capable of solving the problem of ocean pollution, and its industrial value is great.

Claims (9)

1. A resin comprising polybutylene succinate and having an alkali metal content of 0.001 to 6.0 mass ppm.

2. The resin according to claim 1, wherein a ratio (S/Se) of the number of groups derived from succinic acid to the number of groups derived from sebacic acid constituting the polybutylene succinate is in a range of 71/29 to 95/5.

3. The resin according to claim 1, wherein a ratio (S/Se) of the number of groups derived from succinic acid to the number of groups derived from sebacic acid constituting the polybutylene succinate is in a range of 71/29 to 89/11.

4. The resin according to any one of claims 1 to 3, wherein the acid value is 50eq/t or less.

5. The resin according to any one of claims 1 to 4, wherein the content of sulfur atoms is 4.0 mass ppm or less.

6. The resin according to any one of claims 1 to 5, wherein the weight average molecular weight is 10000 ～ 2500000.

7. The resin according to any one of claims 1 to 6, wherein reduced viscosity at 30 ℃ is 0.5dl/g to 4.0dl/g.

8. A resin composition comprising the resin of any one of claims 1 to 7.

9. A molded article comprising the resin according to any one of claims 1 to 7.