JPH10324763A - Biodegradable aliphatic polyester carbonate-based resin extruded foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject foam, having excellent biodegradability and hydrolytic resistance, a high closed-cell ratio and a high expansion ratio by improving melting characteristics of an aliphatic polyester carbonate-based resin and specifying the density. SOLUTION: This biodegradable aliphatic polyester carbonate-based resin extruded foam is obtained by regulating the density thereof to <=0.8 g/cm<3> , preferably <=0.20 g/cm<3> , more preferably <=0.15 g/cm<3> . The resultant foam is produced by infecting a blowing agent into, e.g. an aliphatic polyester carbonate- based resin raw material having 1×10<2> to 1×10<4> Pa.s melt viscosity (at 190 deg.C and 100 sec<-1> shear rate) and >=2 mgf/Pa.s melt tension per unit viscosity while melting and kneading the aliphatic polyester carbonate-based resin raw material in an extruder and then extruding the melt kneaded material from a high- pressure zone to a low-pressure zone. The content of polycarbonate bonds in the resin constituting the foam is preferably 1.8-33 mol.%, more preferably 10-20 mol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded aliphatic polyester carbonate resin foam having excellent biodegradability, hydrolysis resistance, low environmental load and excellent practicability.

[0002]

2. Description of the Related Art In recent years, plastic foams having characteristics such as light weight, elasticity, cushioning property, heat insulation property, moldability and the like have been mainly used for packaging containers, cushioning materials and the like. Since it is difficult to dispose of waste plastics, there is a possibility of polluting the natural environment, which has become a major social problem. For this reason, biodegradable plastics that are decomposed in the natural environment have been studied, and some aliphatic polyesters and alloys of starch and polyvinyl alcohol have been commercialized.

Some foams using these plastics have been developed. However, foams using an alloy of starch and polyvinyl alcohol have poor water resistance because the raw starch is water-soluble. A foam using an aliphatic polyester has a problem that it is easily hydrolyzed because it is a polyester although it has water resistance.

Accordingly, the present inventors have conducted research and development focusing on the fact that polycarbonate is more excellent in hydrolysis resistance than polyester, and as a result, have found that a straight-chain fatty acid obtained by introducing a carbonate component into an aliphatic polyester. It has been found that aromatic polyester carbonates are excellent in hydrolysis resistance while maintaining biodegradability and can be used for films, sheets, fibers and the like (JP-A-7-53693, JP-A-7-53695, 8-27362).

However, these aliphatic polyester carbonates are polymers having good moldability and biodegradability into films, sheets, fibers and the like, but it has been difficult to produce foams. Thus, a foam excellent in both biodegradability and hydrolysis resistance has not yet been obtained.

[0006]

SUMMARY OF THE INVENTION The present invention provides a novel extruded aliphatic polyester carbonate resin foam having excellent biodegradability and hydrolysis resistance, a high closed cell ratio and a high expansion ratio. That is the subject.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that it is difficult to produce a foam because, first, the resin forms bubbles during foaming. Second, as the general method for increasing the melt tension is to polymerize the resin and increase the melt viscosity as a general method to increase the melt viscosity. It has been found that, because the fluidity is reduced, the cells hardly expand during foaming, and a foam cannot be obtained. Therefore, further study was continued, and it was found that by improving the melting properties of the aliphatic polyester carbonate-based resin, the above problem could be solved.
The present invention has been completed.

That is, according to the present invention, a biodegradable aliphatic polyester carbonate-based resin extruded foam having a density of 0.8 g / cm ³ or less is measured at a temperature of 190 ° C. and a shear rate of 100 sec ^−1. Melt viscosity is 1 × 10 ² to 1 × 10 ⁴ Pa · s
A ^{(1 × 10 3 ~1 × 10} 5 poise), and a feature that the melt tension per unit viscosity formed by extrusion foaming of an aliphatic polyester carbonate resin material is 2mgf / Pa · s or higher The biodegradable aliphatic polyester carbonate-based resin extruded foam, wherein the aliphatic polyester carbonate-based resin constituting the foam is a branched aliphatic polyester carbonate-based resin. The biodegradable aliphatic polyester carbonate-based resin, wherein the content of carbonate bonds in the aliphatic polyester carbonate-based resin constituting the foam is 1.8 to 33 mol%. Extruded foams are provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyester carbonate-based resin used as a raw material of the foam of the present invention requires a specific melting property in order to form a foam using a foaming agent. That is, a temperature of 190 ° C. and a shear rate of 100 sec.
The melt viscosity measured under the condition of c ^-1 is preferably 1 ×
10 ² to 1 × 10 ⁴ pa · s (1 × 10 ³ to 1 × 10 ⁵ po
is), more preferably 5 × 10 ^{2 to} 5 × 10 ³ pa ·
s (5 × 10 ^{3 to} 5 × 10 ⁴ poise), and
The melt tension per unit viscosity is preferably 2 mgf / P
a · s or more, more preferably 2.5 mgf / Pa · s or more.

When the melt viscosity is less than 1 × 10 ² Pa · s,
Since the viscosity is too low, dripping occurs immediately after extrusion from a die of an extruder, and sheeting may be difficult. On the other hand, if the melt viscosity exceeds 1 × 10 ⁴ Pa · s, bubbles may not grow because the viscosity is too high.
Therefore, by selecting the range of the melt viscosity in the present invention, an excellent one can be obtained in terms of sheeting and bubble growth. Further, the melt viscosity is 1 × 10 ² to 1 × 10 ⁴ pa ·
Even in the range of s, if the melt tension per unit viscosity is less than the above value, bubbles grow but the melt tension is insufficient, so that even when a foam is obtained, the closed cell ratio is low. There is a possibility that only a high-density foam expanded to such an extent that air bubbles do not burst can be obtained. In addition, it is preferable in terms of thermoformability that the closed cell ratio of the foam measured by the air pycnometer method is 30% or more.

The aliphatic polyester carbonate-based resin having the melting property used as the raw material of the foam of the present invention comprises, in the presence of a transesterification catalyst, an aliphatic dicarboxylic acid compound containing succinic acid as a main component, An aliphatic dihydroxy compound containing 4-butanediol as a main component and a polyhydric alcohol containing three or more hydroxyl groups in the molecule, or a polycarboxylic acid compound containing three or more carboxyl groups in the molecule, or And a polyhydric carboxylic acid having at least one hydroxyl group to obtain an aliphatic polyester oligomer, and a second step of reacting the oligomer with a diaryl carbonate.

The aliphatic polyester carbonate-based resin having the melting property used as a raw material of the foam of the present invention may comprise, in the presence of a transesterification catalyst, an aliphatic dicarboxylic acid compound containing succinic acid as a main component; A 1 'step of reacting an aliphatic dihydroxy compound containing 1,4-butanediol as a main component to obtain an aliphatic polyester oligomer, and a polyhydric alcohol containing at least three hydroxyl groups in the molecule and a diaryl alcohol; It is produced by a method comprising a second 'step of reacting with carbonate.

A polyhydric alcohol having at least three hydroxyl groups in the molecule, a polycarboxylic acid compound having at least three carboxyl groups in the molecule, or a polycarboxylic acid having at least one hydroxyl group in the molecule Is used in an amount of 0.05 mol% to 5 mol%, preferably 0.1 mol% to 3 mol%, based on the aliphatic dicarboxylic acid compound. If it is less than 0.05 mol%, the melt tension and the moldability hardly change and the effect cannot be exhibited,
If it exceeds 5 mol%, gelation tends to occur in a short time, and it becomes extremely difficult to control the molecular weight.

Even when the amount of the polyfunctional compound used is less than 0.05 mol% (including 0 mol%), the organic peroxide is used to such an extent that the obtained resin does not substantially gel. May be appropriately added and finely crosslinked. In addition, the micro-crosslinking which does not substantially generate a gel is defined as a case where the gel fraction of the aliphatic polyester carbonate-based resin is 1 by a boiling xylene method.
%. Here, the gel fraction by the boiling xylene method refers to a gel fraction of 200 m provided with a cooling pipe.
100 g of xylene and 1 g of polymer were placed in a 1 l flask, boiled for 8 hours, and filtered through a 100-mesh wire gauze at 20 ° C.
The amount of the residual gel after air drying for 24 hours was measured, and determined by the following equation 1. [(Residual gel amount: g) / 1 g] × 100 Formula 1 The organic peroxide used for the fine cross-linking, such as dicumyl peroxide or benzoyl peroxide, has a one-minute half-life temperature of an aliphatic polyester carbonate type. The melting point of the resin is preferably higher than that of the resin, and the amount of the resin is preferably 0.005 to 0.1 part by weight based on 100 parts by weight of the resin. If the amount is less than 0.005 parts by weight, the effect of fine crosslinking is not exhibited, and the melt tension per unit viscosity cannot be 2 mgf / Pa · s or more. On the other hand, if it exceeds 0.1 parts by weight, gelation often occurs and the properties of the foam deteriorate.

The first step and the first 'step are carried out in the presence of a catalyst at a temperature of 100 to 250 ° C., preferably 150 to 220 ° C.
At a temperature of 500 ° C. while removing water and excess 1,4-butanediol by-produced during the reaction.
This is a step of producing a polyester oligomer of No. 00.
When the molecular weight of the polyester oligomer is higher than 5,000, the proportion of carbonate bonds in the final polymer is remarkably lowered, and the hydrolysis resistance is lowered. However, the carbonate bond can easily make the molecular weight of the polyester into a polymer as a binder for the oligomer, and when the hydrolysis resistance does not need to be considered so much, the polyester oligomer having a molecular weight exceeding the above-mentioned molecular weight may be used. You may. When the molecular weight of the polyester oligomer is 500 or less, the melting point of the final polymer decreases.

The reaction pressure is selected so as to achieve the above-mentioned object, but may be reduced to 300 mmHg or less for the purpose of accelerating the reaction.

An aliphatic dicarboxylic acid compound containing succinic acid as a main component in the first step and the first 'step;
The reaction with an aliphatic dihydroxy compound containing 4-butanediol as a main component is carried out with the aliphatic dihydroxy compound in excess of the theoretical amount. Specifically, the aliphatic dihydroxy compound is used in an amount of 1.05 to 2.00 mol per 1 mol of the aliphatic dicarboxylic acid compound. Although the reaction time becomes longer as the amount of the aliphatic dihydroxy compound increases,
The acid value tends to decrease. The molecular weight, acid value, and residual amount of the aliphatic dihydroxy compound of the obtained aliphatic polyester oligomer can be controlled by appropriately balancing the distillation rate of the unreacted 1,4-butanediol and the reaction rate. A method in which the conditions of the molar ratio, the catalyst, the temperature, the degree of pressure reduction, and the reaction time are appropriately combined, and a method in which an inert gas is blown at an appropriate flow rate are practical.

For example, the reaction time can be shortened and the 1,4-
Although the remaining amount of butanediol can be reduced, an unreacted carboxylic acid, that is, an acid value increases. An increase in the acid value is not preferable because of problems such as decomposition and coloring due to a side reaction of the diaryl carbonate. On the other hand, an increase in the amount of the catalyst increases the reaction rate, but eventually causes a problem in the thermal stability of the produced polymer. For this reason, the reaction is carried out by adjusting the degree of pressure reduction in three stages using a small amount of catalyst. The first stage is mainly the removal of water produced by condensation, which is usually carried out at normal pressure. The second step is a ripening step for completing the dehydration condensation reaction, that is, for reducing the acid value.
Water and a small amount of 1,4 at a reduced pressure of about 00 to 80 mmHg
The butanediol is distilled off. The third stage is the excess 1,
This is a step of increasing the molecular weight by distilling off 4-butanediol, and finally the degree of vacuum is set to 2 mmHg or less. Adjustment of the molecular weight, that is, the terminal hydroxyl value, can be performed by the amount of 1,4-butanediol distilled. The terminal hydroxyl value is 2
The range of 0 to 200 KOHmg / g is preferred.

The second step is a step of reacting the polyester oligomer obtained in the first step with a diaryl carbonate to form a high molecular weight substance, and the second step is a step of the first step.
This is a step of reacting the polyester oligomer obtained in the step with a polyhydric alcohol having at least three hydroxyl groups in the molecule and a diaryl carbonate to form a high molecular weight polymer.
In both the second step and the second ′ step, the reaction temperature is 150 to 250 ° C.,
Preferably, it is a step of removing phenol and a small amount of 1,4-butanediol or a converted product of 1,4-butanediol by-produced by the reaction at 200 to 230 ° C.

In the second and second steps, the amount of the diaryl carbonate used is determined by the amount of the terminal hydroxyl group of the aliphatic polyester oligomer or the terminal hydroxyl group of the polyester oligomer and the polyhydric alcohol having three or more hydroxyl groups in the molecule. Usually 0.40 to 0.1 to the total amount of hydroxyl groups.
It is used in the range of 60-fold molar amount, more preferably 0.45-0.55 molar amount. The content of the carbonate bond in the obtained polyester carbonate,
It is 1.8 to 33 mol%, preferably 3 to 30 mol%, and more preferably 10 to 20 mol%. As the amount of carbonate bond increases, the hydrolysis resistance improves, but the melting point decreases. Therefore, it is necessary to control the melting point according to the application.

Further, the polyester oligomer used here is not limited to one kind, but two or more kinds of polyester oligomers having different raw materials are produced independently, and an appropriate amount thereof is mixed to form a block copolymer. It is also possible to manufacture.

In these high-molecularization processes, if the reaction temperature is high, the polymerization reaction is fast, but the obtained polymer may be colored, and a high temperature exceeding the above range is not preferable. The reaction is carried out by gradually adjusting the degree of pressure reduction as needed, and it is preferable that the degree of pressure reduction is finally reduced to 3 mmHg or less.

The aliphatic polyester carbonate obtained after the completion of the second and second 'steps contains 1 to 3% by weight of cyclic oligomers. In addition, about 300 ppm of by-product phenol and less than 20 ppm of unreacted diaryl carbonate are contained. May be included. Among the cyclic oligomers,
When a cyclic oligomer composed of two molecules of 4-butanediol and two molecules of succinic acid has an oligomer concentration of more than 0.6% by weight, white crystals are deposited on the surface of the foam after a storage period of about one month. It is preferable to remove it because it may occur. Therefore, to the aliphatic polyester carbonate in the molten state, a catalyst deactivator is added and mixed under a nitrogen atmosphere to deactivate the reaction catalyst. It is preferable to devolatilize and remove the oligomer so as to have a concentration of 0.6% by weight or less. Also, as for phenol, when the amount of phenol is 20 ppm or more,
There is a problem of phenol odor during foam molding, and it is preferable to remove the phenol odor.

As the catalyst deactivator, phosphorus compounds such as phosphoric acid, polyphosphoric acid, phosphorous acid and esters thereof are preferably used. The addition amount is 0.3 to 10 times mol, preferably 0.5 to 5 times mol per 1 mol of the catalyst. For removing the cyclic oligomer, a high temperature and a high degree of vacuum are preferable, the operating temperature is 130 to 300 ° C, preferably 180 to 280 ° C, and the degree of reduced pressure is 10 mmHg or less, preferably 5 mmHg or less, more preferably 2 mmHg.
Hg or less.

Hereinafter, the raw material monomers and the like of the raw material aliphatic polyester carbonate-based resin of the foam of the present invention will be described in detail. As a raw material monomer of the aliphatic polyester carbonate-based resin, at least one of succinic acid (or an alkyl ester thereof) or succinic acid (or an alkyl ester thereof) and an aliphatic dicarboxylic acid compound represented by the following general formula (1) is used. The seed is used in combination with 1,4-butanediol or 1,4-butanediol and at least one aliphatic dihydroxy compound represented by the following general formula (2). R ₁ OOC—R ₂ —COOR ₃ (1) HO—R ₄ —OH (2) (wherein R ₁ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and these are the same. R ₂ and R ₄ represent an alkylene group having 1 to 8 carbon atoms, which may be the same or different.)

Examples of the aliphatic dicarboxylic acid compound represented by the general formula (1) include oxalic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, diglycolic acid,
Sebacic acid, dodecandioic acid, pentadecandioic acid and alkyl esters thereof are exemplified.

The aliphatic dihydroxy compound represented by the general formula (2) includes, for example, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentanediol, hexamethylene glycol,
Examples thereof include propylene glycol, neopentyl glycol, and octanediol.

In the present invention, when the aliphatic dicarboxylic acid compound and the aliphatic dihydroxy compound represented by the general formulas (1) and (2) are used in combination, the amount of succinic acid (or its alkyl ester) or 1,4-butanediol can be reduced. Is preferably at least 80 mol% from the viewpoint of the physical properties of the obtained polymer.

The polyhydric alcohol which is a raw material monomer of the aliphatic polyester carbonate-based resin of the foam of the present invention and contains three or more hydroxyl groups in the molecule includes, for example, glycerin, trimethylolethane, trimethylolpropane, Examples thereof include 1,2,4-butanetriol, pentaerythritol, dipentaerythritol, tripentaerythritol, 3-methylpentane-1,3,5-triol, 1,2,6-hexanetriol, and phloroglucin.

Examples of the polycarboxylic acid compound containing three or more carboxyl groups in the molecule include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, propanetricarboxylic acid, trimesic acid and the like. Etc. are exemplified.

Furthermore, tartaric acid, citric acid and the like are exemplified as polyvalent carboxylic acids containing one or more hydroxyl groups in the molecule.

Specific examples of diaryl carbonate, which is a raw material monomer of the aliphatic polyester carbonate-based resin of the foam of the present invention, include diphenyl carbonate, ditolyl carbonate, and bis (chlorophenyl).
Carbonate and m-cresyl carbonate. Among these diaryl carbonates, diphenyl carbonate is particularly preferred.

The catalyst used in the production of the aliphatic polyester carbonate-based resin for the foam of the present invention includes a zirconium compound or a hafnium compound;
A catalyst comprising a combination of at least one selected from compounds of Y, La, Zn and Sn is preferably used. In this case, the total amount of the catalyst is smaller and a sufficient reaction is obtained as compared with the case of using a zirconium compound or a hafnium compound alone. Speed is obtained. Preferred forms of the compound as the catalyst include fatty acid salts, hydroxides, alcoholates, phenolates, acetylacetonates and the like.

Examples of the zirconium compound and hafnium compound include zirconium acetylacetonate, acetylacetate zirconyl, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetranormal butoxide, zirconium tetratertiary butoxide, zirconyl chloride, zirconium chloride, and sulfuric acid. Zirconium, zirconium oxyacetate, zirconium octoate, zirconium oxystearate, hafnium acetylacetonate, hafnium tetrabutoxide, hafnium tetraisopropoxide and the like are exemplified, but zirconium acetylacetonate and hafnium acetylacetonate are particularly preferably used. .

The compounds of Y, La, Zn and Sn include yttrium acetate, yttrium naphthenate, yttrium tris (acetylacetonate), lanthanum acetate, zinc acetate, zinc acetylacetonate, zinc benzoate and zinc stearate. , Zinc oxide, zinc phosphate, tin oxalate, tin acetylacetonate, dibutyltin laurate,
Examples thereof include dibutyltin oxide and tin chloride, and zinc acetylacetonate, zinc acetate, and dibutyltin oxide are particularly preferably used.

The catalyst may be added in the first step using the catalyst in the above-mentioned combination from the beginning, and in the first step using a zirconium compound or a hafnium compound in the second step. Then, Y, La, Zn
There is a method in which at least one compound selected from the group consisting of Sn and Sn is added to cause a reaction, and either method may be used. It is desired that the amount of the catalyst be as small as possible. Usually, 5 × 10 ⁻⁵ to 1 part by weight, preferably 1 × 10 ⁻⁴ to 2 × 10 ⁻² parts by weight is used per 100 parts by weight of the raw material (reaction) mixture. Is done. In addition, among the aliphatic polyester carbonate-based resins in the present invention, particularly, a branched aliphatic polyester carbonate-based resin is contained in the resin as described in a patent application (Japanese Patent Application No. 8-205599) filed by the present applicant. A component derived from the polyfunctional compound, such as trimethylolpropane, is present and has a branched structure.

Next, the production of the biodegradable aliphatic polyester carbonate resin extruded foam of the present invention will be described. In order to obtain the biodegradable aliphatic polyester carbonate-based resin foam of the present invention, the aliphatic polyester carbonate-based resin obtained by the above-described method is employed. Further, a small amount of other biodegradable resin may be added to the extent that biodegradability and hydrolysis resistance are not impaired. As the resin to be added, an aliphatic polyester resin is preferable. In this case also, the mixture must satisfy the melting characteristics.

In order to produce the foam of the present invention, a raw material containing an aliphatic polyester carbonate resin as a main component is melted and kneaded with an extruder, and a foaming agent is injected while the raw material is impregnated with the foaming agent. After melted and kneaded with an extruder, the melt-kneaded product is extruded from a high pressure region to a low pressure region to produce a foam. If necessary, a bubble regulator such as talc or clay may be added.

The extrusion foam molding method in the present invention includes:
The following various methods can be mentioned. a: Ordinary extrusion foam molding method This is a method in which a foaming agent, a resin, and an additive, if necessary, are melt-kneaded in an extruder, and then extruded under a low pressure through a die located at the tip of the extruder. It is extruded into a sheet or plate. The sheet is then formed into a container or a bag by heating. b: Accumulation foam molding method A foaming agent, a resin, and an additive, if necessary, are melt-kneaded in an extruder, and then these are accumulated in an accumulator under conditions that do not cause foaming, temporarily held, and then discharged under low pressure. This is usually extruded into a thick plate.

The volatile blowing agents used in the present invention include propane, n-butane, iso-butane, n-pentane, i
aliphatic hydrocarbons such as so-pentane and n-hexane, and mixtures thereof; and halogenated hydrocarbons such as methyl chloride, methylene chloride, difluoroethane, chlorodifluoromethane, tetrafluoroethane, and chlorodifluoroethane, and mixtures thereof. . The thermal decomposition type foaming agent used in the present invention includes azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, P, P'-oxybisbenzenesulfonylhydrazide, calcium azide, ammonium carbonate, ammonium bicarbonate, And sodium bicarbonate.

The amount of these foaming agents is 0.006 mol or more, preferably 0.02 mol or more per 100 g of the resin. If the amount of the foaming agent is less than 0.006 mol, the density of the foam obtained exceeds 0.8 g / cm ^3, and the properties (buffer properties and heat insulation properties) of the foam are insufficient and the characteristics of the foam are not exhibited. .

The biodegradable aliphatic polyester carbonate-based resin foam of the present invention has a density of 0.8 g / cm ³ or less, preferably 0.20 g / cm ³ or less, more preferably 0.15 g / cm ³ or less. is there. 0.8g / cm density
^If it exceeds ³ , the cushioning property and the heat insulating property become insufficient, and the characteristics as a foam are not exhibited. In addition, it is preferable that the density of the aliphatic polyester carbonate-based resin which is a raw material of the foam of the present invention is 1.2 to 1.3 g / cm ³ .

Furthermore, the biodegradable aliphatic polyester carbonate-based resin foam of the present invention has an average cell diameter of 20 to 1000 μm, preferably 100 to 500 μm.
It is desirable that When the average cell diameter is in this range, good mechanical strength, appearance, texture, etc. are obtained.
The average cell diameter can be determined as the average of the average cell diameter in the width direction cross section of the foam and the average cell diameter in the extrusion direction of the foam in the extrusion direction cross section. Also,
The closed cell rate of the foam of the present invention is 15% or more, preferably 30% or more. The cell shape of the foam of the present invention is spherical and / or flat, and the resin foam of the present invention is excellent in flexibility and mechanical strength.

In the present invention, the content of carbonate bonds in the biodegradable aliphatic polyester carbonate-based resin constituting the foam is 1.8 to 33 mol%, preferably 3 to 33 mol%.
-30 mol%, more preferably 10-20 mol%. When the content of the carbonate bond is insufficient, the hydrolysis resistance is inferior, and when exposed to a humid atmosphere, the mechanical strength is significantly reduced. On the other hand, when the carbonate bond content is excessive, although the resin exhibits good hydrolysis resistance, the melting point of the resin decreases, and the heat resistance of the foam deteriorates. The adjustment of the amount of carbonate bond is appropriately performed during the polymerization of the raw materials.

[0045]

The present invention will be described below with reference to examples and comparative examples. Table 1 shows the aliphatic polyester carbonate resin and the comparative aliphatic polyester resin which are the raw materials of the foam of the present invention, and their physical properties. In addition, physical properties of each resin,
The production example is as shown below. Melt Viscosity As a melt viscosity measuring device, Cheist's Leovis 21
00, a melt of the base resin was fed from a tip nozzle attached to the apparatus to a resin temperature of 190 ° C. and a shear rate of 100 s.
It was measured by extruding and flowing under the condition of ec ^-1 . In this case, the hole diameter D of the nozzle was set to 1.0 mm, and the ratio L / D of the length L of the nozzle to the hole diameter D of the nozzle was set to 10. Melt tension As a melt tension measuring device, a melt tension tester type 2 manufactured by Toyo Seiki Seisaku-sho, Ltd. was used.
It was measured by extruding and flowing at 0 ° C. and a piston speed of 10 mm / min. In this case, the nozzle hole diameter D is 2.0 mm, the nozzle length L and the nozzle hole diameter D
L / D was set to 4. Melt tension per unit viscosity Using the measured values of the melt viscosity and the melt tension obtained as described above, the melt tension was divided by the melt viscosity. Production Examples of Resins AD

In this production example, the molecular weights of the polyester oligomer and the polyester carbonate were determined by using GPC (GPC Sys by Showa Denko KK) using chloroform as a solvent.
Mn and Mn in terms of styrene. The hydroxyl value and the acid value are based on JIS-K1557.
Quantified according to Melt index is JIS-K
Measured according to 7210 condition 4. Hereinafter, production examples of the resin of the present invention will be described.

Production Example 1 18.74 k of succinic acid was placed in a first 50 liter reactor equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube.
g (158.7 mol), 1,4-butanediol 21.
43 kg (237.8 mol), 149.07 g (1.111 mol) of trimethylolpropane, 745 mg of zirconium acetylacetonate and 1.50 g of zinc acetylacetonate were charged, and the mixture was heated to a temperature of 150 to 150 g under a nitrogen atmosphere.
The reaction was performed at 220 ° C. for 2 hours to distill water. continue,
After aging for 3 hours at a reduced pressure of 150 to 50 mmHg, the dehydration reaction was allowed to proceed. Further, the degree of decompression was gradually increased so that the degree of decompression finally became 2 mmHg or less, and water and 1,4-butanediol were further distilled. When the total distillation amount reached 9.92 kg, the reaction was stopped. did. Total reaction time was 6.5 hours. The number average molecular weight of the obtained oligomer is 16
00, the terminal hydroxyl value was 120 KOH mg / g, and the acid value was 0.80 KOH mg / g. Next, 30.4 kg of the obtained oligomer was stirred with a stirrer, a fractionating condenser,
A 50-liter second reactor equipped with a thermometer and a gas inlet tube was charged, and 6.97 kg of diphenyl carbonate was added. The temperature was finally reduced to 1 mmHg at a temperature of 210 to 220 ° C, and the reaction was carried out for 3 hours while distilling off phenol. The pressure was released by nitrogen, and 300 g of a polyester carbonate master batch containing 0.7 g of polyphosphoric acid was added. After stirring and mixing, the mixture was taken out into a strand and pelletized. The obtained high molecular weight product was uncolored, had a weight average molecular weight (Mw) measured by GPC of 210,000, a melt tension of 12.2 gf, and a melt index of 4.0 g / 10 min. (Raw material A)

Production Example 2 18.74 k of succinic acid was placed in a 50-liter first reactor equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube.
g (158.7 mol), 1,4-butanediol 21.
43 kg (237.8 mol), 745 mg of zirconium acetylacetonate and 1.50 g of zinc acetylacetonate were charged, and the temperature was 150 to 22 under a nitrogen atmosphere.
The reaction was carried out at 0 ° C. for 2 hours to distill water. Then, 15
Aging was performed at a reduced pressure of 0 to 80 mmHg for 3 hours, and a dehydration reaction was allowed to proceed. Furthermore, the degree of vacuum was gradually increased so that the degree of vacuum finally became 2 mmHg or less, and water and 1,4-butanediol were further distilled. When the total amount of distilled water reached 10.7 kg, the reaction was stopped. . Total reaction time was 7.0 hours. The number average molecular weight of the obtained oligomer is 2100,
The terminal hydroxyl value was 90 KOHmg / g, and the acid value was 0.1 KOH.
70 KOHmg / g. Next, 29.5 kg of the obtained oligomer was stirred with a stirrer, a fractionating condenser, a thermometer,
A 50-liter second reactor equipped with a gas inlet tube was charged, and 5.09 kg of diphenyl carbonate was added.
At a temperature of 210 to 220 ° C., the pressure was finally reduced to 1 mmHg, and the reaction was carried out for 3.5 hours while distilling off phenol. Release the reduced pressure with nitrogen, and add 0.7 g of polyphosphoric acid to 30
After adding 0 g of a polyester carbonate master batch, stirring and mixing, the mixture was taken out into a strand and pelletized. The obtained high molecular weight product was uncolored and had a weight average molecular weight (Mw) of 220,000 as measured by GPC.
Melt tension is 1.2 gf, melt index is 3.0 g
/ 10 minutes. (Raw material D) Add 0.01 part of dicumyl peroxide to Raw material D and add 2 parts.
The mixture was kneaded at 00 ° C. for 5 minutes or more and finely crosslinked, taken out into a strand, and pelletized. (Raw material B)

Production Example 3 18.74 k of succinic acid was placed in a 50-liter first reactor equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube.
g (158.7 mol), 1,4-butanediol 21.
43 kg (237.8 mol), 44.20 g of glycerin
(0.48 mol), 745 mg of zirconium acetylacetonate and 1.50 g of zinc acetylacetonate were charged and reacted under a nitrogen atmosphere at a temperature of 150 to 220 ° C. for 2 hours to distill water. Subsequently, 150-80 mm
The mixture was aged at a reduced pressure of Hg for 3 hours to allow a dehydration reaction to proceed.
Furthermore, the degree of vacuum was gradually increased so that the degree of vacuum finally became 2 mmHg or less, water and 1,4-butanediol were further distilled, and the reaction was stopped when the total amount of distilled water became 9.26 kg. . Total reaction time was 6.0 hours. The number average molecular weight of the obtained oligomer was 1300, the terminal hydroxyl value was 144 KOH mg / g, and the acid value was 0.80 KOH.
mg / g. Next, the obtained oligomer 30.9
5 kg was charged into a 50 liter second reactor equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube, and 8.52 kg of diphenyl carbonate was added. Temperature 210
At 減 圧 220 ° C., the pressure was finally reduced to 1 mmHg, and the mixture was reacted for 3.5 hours while distilling off phenol. The pressure was released by nitrogen, and 300 g of a polyester carbonate master batch containing 0.7 g of polyphosphoric acid was added. After stirring and mixing, the mixture was taken out into a strand and pelletized.
The obtained high molecular weight product was uncolored, had a weight average molecular weight (Mw) measured by GPC of 220,000, a melt tension of 3.7 gf, and a melt index of 3.0 g / 10 min. (Raw material C)

[0050]

[Table 1]

Examples 1 to 5, Comparative Example 1 Production of Foam No. 1 extruder φ50mm, No. 2 extruder φ65mm
The raw material having the melting characteristics shown in Table 1 and 0.2% by weight of talc as a cell regulator were charged into a tandem extruder consisting of 1 After the foaming agent shown in Table 2 was injected and kneaded in the middle of the extruder, the resin temperature was 110 to 120 ° C and the diameter was 60
It was extruded from a cylindrical die of mm. Then 200mm in diameter
Then, cooling and slitting were performed using the mandrel described above to obtain a foamed sheet shown in Table 2. In addition, the measurement of the physical properties of each foam sheet and the evaluation of the performance are performed by the following methods. Measurement of closed cell ratio The closed cell ratio of the foam was calculated by the following equation using an air pycnometer method. Fc (%) = 100 × {Vx−Va (ρf / ρs)} /
{Va−Va (ρf / ρs)} Fc: Closed cell ratio (%) Va: Apparent volume of foam (cm ³ ) Vx: Actual volume of foam (cm ³ ) ρf: Foam density (g / cm ³ ) ρs : Density of base resin (g / cm ³ ) Evaluation of biodegradability Biodegradability was measured by burying the obtained foam sheet in a soil at a depth of 10 cm in Kanuma City, Tochigi Prefecture for 3 months, and then observing the shape change. ：: Decomposed so that the shape cannot be confirmed Δ: Decomposed, but the shape can be confirmed. ×: No change in shape was observed. Evaluation of hydrolysis resistance After curing in an atmosphere at a temperature of 60 ° C. and a relative temperature of 80% for 100 hours, a tensile test was carried out in accordance with JIS K6767, and a retention of the elongation at break before the test was measured. ：: retention rate of 90% or more. Δ: Retention rate of 80% or more and less than 90% X: Retention rate of less than 80% Measurement of carbonate bond The content of carbonate bond was determined by NMR (JEOL Ltd.)
The ratio was determined as the ratio (mol%) of the carbonate bond to the total of the dicarboxylic acid ester bond and the carbonate bond by ¹³ C-NMR using NMR EX2-70).

[0052]

[Table 2]

As is clear from Table 2, in Examples 1 to 5, good foamed sheets were obtained in all cases. In Comparative Example 1, a foam was obtained, but the hydrolysis resistance was poor.

Next, the values of the melt viscosity and the melt tension of the resin defoamed by pressing the foam obtained in each of the Examples and Comparative Examples at a temperature of 200 ° C. under a pressure of 20 kg / cm ² for 5 minutes are described. Are shown in Table 3. In addition, the measurement of these physical properties was performed in the same manner as the above-mentioned measuring method.

[0055]

[Table 3]

From Tables 3 and 1, it can be seen that the melt viscosities and the melt tensions of the resins obtained by defoaming the foams of Examples and Comparative Examples are slightly lower than before foaming.

[0057]

According to the present invention, the foam has not only basic properties such as good surface condition and cell shape, excellent cushioning property and heat insulation property, but also biodegradability and hydrolysis resistance. But an excellent foam is provided. The foam is extremely useful as an alternative material such as a conventionally used polyolefin-based or polystyrene-based resin foam, and can be used in various shapes or forms such as a sheet, a plate, a bar, and a net. It is excellent in biodegradability and does not pollute the natural environment. Particularly, a sheet-like material is suitable as a packaging material per se or as a thermoforming material for a container or the like.

Continued on the front page (72) Inventor Kyohei Takakuwa 22 Wadai, Tsukuba, Ibaraki Prefecture, Mitsubishi Gas Chemical Research Laboratory (72) Inventor Maki Ito 22 Wadai, Tsukuba City, Ibaraki Prefecture, Mitsubishi Gas Chemical Research Laboratory (72) Invention Person Mitsuru Nakamura 22 Wadai, Tsukuba City, Ibaraki Pref., Mitsubishi Gas Chemical Research Laboratory (72) Inventor Akira Iwamoto 10-3 Satsukicho, Kanuma City, Tochigi Prefecture JSP Kanuma Research Laboratories Co., Ltd. 10-3 Satsuki-cho, Kanuma-shi JSP Kanuma Research Institute Co., Ltd. (72) Inventor Yoshiaki Momose 10-3 Satsuki-cho Kanuma-city, Tochigi Pref.

Claims (4)

[Claims] 1. An extruded biodegradable aliphatic polyester carbonate resin foam having a density of 0.8 g / cm ³ or less. 2. Temperature 190 ° C., shear rate 100 sec ⁻¹
The melt viscosity measured under the condition of 1 × 10 ² to 1 × 10 ⁴
Pa · s, and the melt tension per unit viscosity is 2
2. The extruded biodegradable aliphatic polyester carbonate resin foam according to claim 1, wherein an aliphatic polyester carbonate resin raw material having a mgf / Pa · s or more is extruded and foamed. 3. The biodegradable aliphatic polyester carbonate resin extrusion according to claim 1, wherein the aliphatic polyester carbonate resin constituting the foam is a branched aliphatic polyester carbonate resin. Foam. 4. The aliphatic polyester carbonate-based resin constituting the foam has a carbonate bond content of 1.
The extruded biodegradable aliphatic polyester carbonate resin foam according to any one of claims 1 to 3, wherein the amount is 8 to 33 mol%.