JPH06248104A - Production of polyester foam - Google Patents

Abstract

PURPOSE:To produce a foam which is biodegradable when buried in soil, excellent in mechanical strengths such as tensile and impact strengths, and useful as a cushioning material, a thermal insulator, a packaging material, a food container, a screen, etc. CONSTITUTION:An aliph. polyester having a melt viscosity of 1.0X10<3>-1.0X10<6>P at 190 deg.C under a shear rate of 100sec<-1> and a m.p. of 70-190 deg.C is thermally foamed using a blowing agent, giving a foam which is biodegradable. excellent in mechanical strengths such as tensile and impact strengths, and useful as a cushioning material, a thermal insulator, a packaging material, a food container, a screen, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a foamed product which is biodegradable, uses an aliphatic polyester having a practically sufficient high molecular weight and specific melting characteristics and is excellent in thermal stability and mechanical strength. Manufacturing method.

[0002]

2. Description of the Related Art In recent years, plastic foams, which are characterized by light weight, elasticity, moldability, etc., are mainly used for packaging containers, cushioning materials, etc. Since it is difficult to treat, it has a possibility of contaminating rivers, oceans, and soils, which has become a major social problem, and the emergence of biodegradable plastics for preventing this contamination has long been awaited. , Poly (3-hydroxybutyrate) produced by fermentation with microorganisms
Also known are blends of starch, which is a natural polymer of blend type, and general-purpose plastics. However, the former has a drawback that the raw material unit is very bad because the thermal decomposition temperature of the polymer is close to the melting point, the moldability is poor, and microorganisms produce it. Further, in the latter, since the natural polymer itself is not thermoplastic, moldability is difficult and the range of use is greatly restricted. On the other hand, it has been known that aliphatic polyester has biodegradability, but it has hardly been used because a high-molecular-weight substance sufficient to obtain practical physical properties of molded articles cannot be obtained. Recently, ε-caprolactone was found to have a high molecular weight by ring-opening polymerization and has been proposed as a biodegradable resin, but its melting point is as low as 62 ° C.,
Since the raw material is expensive, it is limited to special purposes.
Glycolic acid and lactic acid have high molecular weights obtained by ring-opening polymerization of glycolide and lactide, and are used in medical fibers, etc., but their melting point and decomposition temperature are close to each other, and they have drawbacks in molding processability. It has not been used in large quantities in containers, cushioning materials, etc.

Usually, polystyrene and polyethylene are used for molding foams, and high molecular weight polyesters used in the packaging field (the high molecular weight polyesters referred to here are those having a number average molecular weight of 10,000 or more). Polyethylene terephthalate, which is a condensate of terephthalic acid (including dimethyl terephthalate)) and ethylene glycol, has not been used in this field, and reports of attempts to impart biodegradability. The present situation is that it has not been done yet. Therefore, conventionally, the idea of forming a foam by using an aliphatic polyester having biodegradability, which is an aliphatic type of dicarboxylic acid among these materials, and which is intended to be put into practical use It can be said that there is nothing. One of the reasons why the idea of practical application has not been born is that the melting point of the aliphatic polyester is 100 ° C. or less, although the foam requires special molding conditions and physical properties of the molded product. Almost all of them have poor thermal stability when melted, and more importantly, the properties of this aliphatic polyester, particularly the mechanical properties represented by tensile strength, are the same level as those of the polyethylene terephthalate. Even the average molecular weight shows a remarkably inferior value, and it is considered that it was difficult to conceive the idea of obtaining a molded product requiring strength. One of the reasons for this is that the research that expects to improve the physical properties by further increasing the number average molecular weight of the aliphatic polyester has not progressed sufficiently due to its poor thermal stability.

[0004]

DISCLOSURE OF THE INVENTION The present invention uses these aliphatic polyesters as its components, has a practically sufficient high molecular weight, and is excellent in mechanical properties represented by thermal stability and tensile strength. Another object of the present invention is to provide a method for producing a foam which is biodegradable as one of waste disposal means, that is, which can be decomposed by microorganisms and the like, and which can be easily disposed of after use.

[0005]

The present inventors have studied various reaction conditions for obtaining a polyester foam having a high molecular weight and sufficient practicability. A specific aliphatic polyester having a sufficiently high molecular weight was obtained, and it was found that the foam produced therefrom has not only the above-mentioned biodegradability but also excellent thermal stability and mechanical strength, and completed the present invention. Came to do.

That is, the gist of the present invention is (A) a temperature of 190
Melt viscosity at ℃ and shear rate 100 sec ^-1 is 1.0
× 10 ^{3 to} 1.0 × 10 ⁶ poise, melting point 70 to
A method for producing a foam in which a volatile or heat-decomposable foaming agent or a heat-decomposable foaming agent and a cross-linking agent are used in combination with an aliphatic polyester having a temperature of 190 ° C., (B) the aliphatic polyester has a number average molecular weight of 10 More than 1,000 and 0.0
Method for producing foam of (A) containing 3 to 3.0% by weight of urethane bond, (C) Aliphatic polyester prepolymer having a number average molecular weight of 5,000 or more and a melting point of 60 ° C. or more 10.
0 part by weight, 0.1 to 5 parts by weight of a diisocyanate to obtain a (A) or (B) foam production method, (D) foaming ratio is 1.02 to 50 times There is a method for producing a foam according to (A), (B) or (C). Hereinafter, the content of the present invention will be described in detail.

The term "aliphatic polyester" as used in the present invention means two components of glycols and dicarboxylic acid (or acid anhydride thereof), or, if necessary, a trifunctional or tetrafunctional polyfunctional compound as a third component. The main component is a polyester obtained by reacting with at least one polyfunctional component selected from a polyhydric alcohol, an oxycarboxylic acid and a polyvalent carboxylic acid (or an acid anhydride thereof), and the end of the molecule. A relatively high-molecular-weight polyester prepolymer having a hydroxyl group in is prepared, and this is further polymerized with a coupling agent.

Conventionally, a low molecular weight polyester prepolymer having a hydroxyl group as a terminal group and a number average molecular weight of 2,000 to 2,500 is reacted with diisocyanate as a coupling agent to obtain a polyurethane, a rubber, It is widely used as foam, paint and adhesive. However, the polyester prepolymers used in these polyurethane foams, paints and adhesives are
The maximum number average molecular weight that can be synthesized without catalyst is 20,
It is a low molecular weight prepolymer having an amount of 0 to 2,500, and the amount of diisocyanate used is 10 to 20 parts by weight for 100 parts by weight of this low molecular weight prepolymer in order to obtain practical physical properties as a polyurethane. When such a large amount of diisocyanate is added to the melted low molecular weight polyester at 150 ° C. or higher, gelation occurs and a usual melt-moldable resin cannot be obtained.
Therefore, polyester obtained by reacting a large amount of diisocyanate with such a low molecular weight polyester prepolymer as a raw material cannot be used as a raw material for the method for producing a foam of the present invention.

As in the case of polyurethane rubber, a method of adding a diisocyanate to convert a hydroxyl group into an isocyanate group and further increasing the number average molecular weight with glycol can be considered. As described above, in order to obtain practical physical properties, the amount is 10 parts by weight or more based on 100 parts by weight of the prepolymer, and there is a problem similar to the above. If a relatively high molecular weight polyester prepolymer is used, the heavy metal-based catalyst necessary for the synthesis of the prepolymer remarkably promotes the reactivity of the above-mentioned amount of the isocyanate group, resulting in poor storage stability, crosslinking reaction, and branching. If the polyester prepolymer synthesized without a catalyst is used, the number average molecular weight is limited to 2,500, even if it is high.

The polyester prepolymer for obtaining the aliphatic polyester used in the present invention is of a relatively high molecular weight as described above containing the catalyst for its synthesis,
A saturated aliphatic polyester having a terminal group substantially a hydroxyl group, a number average molecular weight of 5,000 or more, preferably 10,000 or more and a relatively high molecular weight, and a melting point of 60 ° C. or more, and glycols. And a polybasic acid (or its anhydride) are subjected to a catalytic reaction. When the number average molecular weight is less than 5,000, it is 0.1 to be used in the present invention.
With a small amount of the coupling agent of 5 parts by weight, it is not possible to obtain a polyester having a good physical property for use in a method for producing a foam. The polyester prepolymer having a number average molecular weight of 5,000 or more has a hydroxyl value of 30 or less,
By using a small amount of coupling agent, a high molecular weight polyester can be synthesized without producing a gel during the reaction because it is not affected by the remaining catalyst even under severe conditions such as a molten state.

That is, in the aliphatic polyester used in the present invention, a polyester prepolymer comprising an aliphatic glycol and an aliphatic dicarboxylic acid and having a number average molecular weight (Mn) of 5,000 or more, preferably 10,000 or more, for example, a cup It has a structure linked through a urethane bond derived from diisocyanate as a ring agent. Furthermore, in the aliphatic polyester used in the present invention, the above polyester prepolymer has a long chain branch derived from a polyfunctional component, which is, for example, via a urethane bond derived from diisocyanate as a coupling agent. It has a chained structure. When an oxazoline, diepoxy compound or acid anhydride is used as the coupling agent, the polyester prepolymer has a chain structure via an ester bond.

Examples of glycols used include ethylene glycol, 1,4-butanediol, and 1,6.
-Hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like can be mentioned. Ethylene oxide can also be utilized. You may use these glycols together.

Aliphatic dicarboxylic acids (or their acid anhydrides) which react with glycols to form aliphatic polyesters include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and anhydrous. Adipic acid and the like are generally commercially available and can be used in the present invention. You may use together aliphatic dicarboxylic acid (or its acid anhydride).

(Third component) In addition to these glycols and dicarboxylic acids, a trifunctional or tetrafunctional polyhydric alcohol, oxycarboxylic acid and polycarboxylic acid (as a third component) may be added, if necessary. Or its acid anhydride)
At least one polyfunctional component selected from the above may be added and reacted. Addition of this third component causes branching of the long chain in the molecule, increasing the molecular weight and increasing the Mw.
/ Mn becomes large, that is, the molecular weight distribution becomes wide,
Desired properties can be imparted to film forming and the like. The amount of the polyfunctional component added is, in order to eliminate the risk of gelation, in the case of trifunctional with respect to 100 mol% of the total components of the aliphatic dicarboxylic acid (or its acid anhydride), it is 0. 1 to 5 mol%, and 0.1 to 4 in the case of tetrafunctionality
It is 3 mol%.

(Polyfunctional component) Examples of the polyfunctional component used as the third component include trifunctional or tetrafunctional polyhydric alcohols, oxycarboxylic acids and polycarboxylic acids. Typical examples of the trifunctional polyhydric alcohol component are trimethylolpropane, glycerin and their anhydrides, and typical examples of the tetrafunctional polyhydric alcohol component are pentaerythritol.

The trifunctional oxycarboxylic acid component is (i)
There are two types of carboxyl groups and one hydroxyl group in the same molecule, and (ii) one carboxyl group and two hydroxyl groups in the same molecule, but commercial products are easy and low cost. In terms of availability at
Malic acid (i), which shares two carboxyl groups and one hydroxyl group in the same molecule, is practically advantageous and sufficient for the purpose of the present invention. There are the following three types of tetrafunctional oxycarboxylic acid components. That is, (i)
A type in which three carboxyl groups and one hydroxyl group are shared in the same molecule, (ii) A type in which two carboxyl groups and two hydroxyl groups are shared in the same molecule, (iii) Three There is a type that shares a hydroxyl group of 1 and a carboxyl group in the same molecule, and both types can be used, but from the viewpoint that commercial products are easily available at low cost, citric acid And
Tartaric acid is practically advantageous and sufficient for the purposes of the present invention.

As the trifunctional polycarboxylic acid (or acid anhydride thereof) component, for example, trimesic acid, propanetricarboxylic acid, etc. can be used, but trimellitic anhydride is advantageous in practical use, and the present invention Is sufficient for the purpose of. Tetrafunctional polycarboxylic acid (or its acid anhydride)
In the literature, there are various types such as aliphatic, cycloaliphatic, and aromatic, but from the viewpoint that commercial products can be easily obtained, for example, pyromellitic dianhydride, benzophenonetetracarboxylic acid anhydride, cyclopentane Tetracarboxylic acid anhydrides are mentioned and are sufficient for the purposes of the invention.

These glycols and aliphatic dicarboxylic acids are mainly composed of an aliphatic type, but a small amount of other components such as an aromatic type may be used together. However, if other components are introduced, biodegradability deteriorates, so the content is 20% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less.

The polyester prepolymer for an aliphatic polyester used in the present invention has a terminal group which is substantially a hydroxyl group. For that purpose, the glycols and the aliphatic dicarboxylic acid (or acid anhydride thereof) used in the synthesis reaction are used. As for the use ratio of), it is necessary to use glycols in some excess.

The synthesis of relatively high molecular weight polyester prepolymers requires the use of a deglycolization reaction catalyst during the deglycolization reaction following esterification. Examples of the deglycolization reaction catalyst include titanium compounds such as acetoacetoyl type titanium chelate compounds and organic alkoxy titanium compounds. These titanium compounds can be used in combination. Examples of these include diacetoacetoxyoxytitanium ("Narsem titanium" manufactured by Nippon Kagaku Sangyo Co., Ltd.), tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium and the like. The titanium compound is used in an amount of 0.001-1 with respect to 100 parts by weight of the polyester prepolymer.
Parts by weight, preferably 0.01 to 0.1 parts by weight. The titanium compound may be added from the beginning of esterification or immediately before the deglycolization reaction.

Further, the number average molecular weight is 5,000 or more,
Coupling agents are preferably used to increase the number average molecular weight of polyester prepolymers having 10,000 or more end-groups which are substantially hydroxyl groups. Examples of the coupling agent include diisocyanate, oxazoline, diepoxy compound, acid anhydride, and the like.
Diisocyanate is particularly preferable. In the case of an oxazoline or diepoxy compound, it is necessary to react the hydroxyl group with an acid anhydride or the like to convert the terminal into a carboxyl group before using the coupling agent. The type of diisocyanate is not particularly limited, but for example, 2,
4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-
Examples include naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and especially hexamethylene diisocyanate,
It is preferable from the viewpoint of the hue of the produced resin and the reactivity when adding polyester.

The amount of these coupling agents added is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the polyester prepolymer. If it is less than 0.1 part by weight, the coupling reaction is insufficient, and if it exceeds 5 parts by weight, gelation tends to occur.

The addition is preferably carried out under the condition that the polyester prepolymer is in a uniform molten state and can be easily stirred. It is not impossible to add it to a solid polyester prepolymer and melt and mix it through an extruder, but add it to an aliphatic polyester production apparatus or to a molten polyester prepolymer (for example, in a kneader). It is practical to do so.

The aliphatic polyester used in the present invention is required to have specific melting characteristics in order to form a foam by using it together with a foaming agent. That is, the melt viscosity at a temperature of 190 ° C. and a shear rate of 100 sec ⁻¹ is 1.0 × 10 ³ to
1.0 × 10 ⁶ poise, preferably 5.0 × 10
^{3 to} 5.0 × 10 ⁵ poise, 7.0 × 10 ^{3 to} 1.0 ×
10 ⁵ poise is particularly preferred. If it is less than 1.0 × 10 ³ poise, bubbles cannot be formed because the viscosity is too low.
If it exceeds 0 × 10 ⁶ poise, the viscosity will be too high and bubbles cannot grow, so that a practical foam cannot be obtained. The melt viscosity was measured with a nozzle diameter of 1.0 mm and L / D = 1.
From the graph of the relationship between the apparent viscosity and the shear rate measured at a resin temperature of 190 ° C. using a No. 0 nozzle, the shear rate is 100 sec.
The viscosity at ^-1 was determined.

Further, the melting point of the aliphatic polyester used in the present invention is required to be 70 to 190 ° C, more preferably 70 to 150 ° C, particularly preferably 80 to 135 ° C. If it is less than 70 ° C, the heat resistance is insufficient, and if it exceeds 190 ° C, it is difficult to manufacture.
In order to obtain a melting point of 70 ° C or higher, the polyester prepolymer needs to have a melting point of 60 ° C or higher.

When the aliphatic polyester used in the present invention contains a urethane bond, the amount of urethane bond is 0.03 to 3.0% by weight, preferably 0.05 to 2.0% by weight, and 0. 0.1 to 1.0% by weight is particularly preferable. The amount of urethane bond is measured by C ₁₃ NMR and agrees well with the charged amount. If it is less than 0.03% by weight, the effect of increasing the molecular weight by the urethane bond is small and the moldability is poor, and if it exceeds 3.0% by weight, gel is generated.

When using the aliphatic polyester in the method for producing a foam according to the present invention, if necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, etc., as well as a lubricant, a wax, a colorant, a crystal, etc. It goes without saying that a chemical accelerating agent, a reinforcing fiber and the like can be used in combination. That is, as the antioxidant, hindered phenolic antioxidants such as pt-butylhydroxytoluene and pt-butylhydroxyanisole, sulfur-based antioxidants such as distearylthiodipropionate and dilaurylthiodipropionate. Antioxidants, etc.
Examples of heat stabilizers include triphenyl phosphite, trilauryl phosphite, and trisnonyl phenyl phosphite, and examples of ultraviolet absorbers include pt-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-. 4-methoxy-2'-carboxybenzophenone, 2,4,5-trihydroxybutyrophenone, etc., lubricants such as calcium stearate, zinc stearate, barium stearate, sodium palmitate, etc., and antistatic agents such as N, N. -Bis (hydroxyethyl) alkylamine, alkylamine, alkylallyl sulfonate, alkyl sulfonate, etc., hexabromocyclododecane as a flame retardant,
Tris- (2,3-dichloropropyl) phosphate,
Examples include pentabromophenyl allyl ether.

(Foaming with Volatile Foaming Agent) Volatile foaming agents used in the present invention include aliphatic hydrocarbons such as propane, butane, pentane, isobutane, neopentane, isopentane, hexane and butadiene, as well as methyl chloride and methylene. Chloride, dichlorofluoromethane, chlorotrifluoromethane, dichlorodifluoromethane,
Halogenated hydrocarbons such as chlorodifluoromethane and trichlorofluoromethane. In order to produce a foam using such a volatile foaming agent, a volatile foaming agent is injected while melting and kneading a raw material containing an aliphatic polyester as a main component with an extruder, or a volatile foaming agent for the raw material. A foam having a foaming ratio of 1.02 to 50 times can be produced by extruding a material impregnated with a foaming agent from the extruder into the atmosphere.

If the expansion ratio is less than 1.02 times, the characteristics as a foam do not occur, and if the expansion ratio exceeds 50 times, the cells become continuous and the surface unevenness becomes large, and it cannot be a practical foam. . The kneading temperature needs to be a temperature equal to or higher than the melting point of the aliphatic polyester and is 100 ° C to 2 ° C.
70 ° C., and more preferably 100 ° C. to 250 ° C. If the kneading temperature is less than 100 ° C., the viscosity is too high and it is difficult to knead, and if it exceeds 270 ° C., the resin deteriorates, which is disadvantageous.

Combustion heat value of foam (JIS M8814
(Measured by the calorimeter method) of 7,000 kcal / kg or less, and there is little corrosion of the material of the equipment when burning waste.

(Foaming with a heat-decomposable foaming agent) The heat-decomposable foaming agent used in the present invention is various organic and inorganic heat-decomposable foaming agents, and examples of the organic foaming agent include azodicarbonamide. , N, N′-dinitrosopentamethylenetetramine, PP′-oxybisbenzenesulfonylhydrazide and the like. The inorganic foaming agents include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium azide and the like.

The expansion ratio is usually 1.02 to 30.00 times. A foam made of such an aliphatic polyester having an expansion ratio of 1.02 to 30.00 is a heat-decomposable foaming agent of 0.5 to 3 with respect to 100 parts by weight of the aliphatic polyester.
It can be produced by mixing 0 parts by weight with or after mixing, and then heating the mixture to the decomposition temperature of the foaming agent or higher. If the expansion ratio is less than 1.02 times, the characteristics as a foam will not be produced, and if the expansion ratio exceeds 30 times, the cells will be continuous and the surface unevenness will become large, and it will not be a practical foam.

The kneading method for dispersing the foaming agent can be carried out by any known method, but it is preferably kneading with a kneader, roll or extruder. The kneading temperature needs to be a temperature equal to or higher than the melting point of the aliphatic polyester, and is usually 100 to 270 ° C., more preferably 15
It is 0 to 250 ° C. When kneading at a temperature equal to or higher than the decomposition temperature of the foaming agent, it is necessary to carry out under pressure. If the kneading temperature is less than 100 ° C., the viscosity is too high and the kneading is difficult.
If the temperature exceeds 0 ° C, the resin deteriorates, which is inconvenient. The heating method for decomposing the foaming agent is an extruder, press,
A heating device such as a hot-air stove, an infrared heating furnace, or a molten salt bath can be used. In particular, when heating under pressure using an extruder, a press or the like, a foam can be obtained by reducing the pressure to atmospheric pressure. (Foaming with a cross-linking agent)

The cross-linking agent used in the present invention is an organic peroxide having a decomposition temperature not lower than the melting point of the resin, such as dicumyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, t-butyl peroxyisopropyl carbonate and the like. Can be given.

A foam made of such an aliphatic polyester having an expansion ratio of 2 or more is an aliphatic polyester 10
0.5 to 10 parts by weight of a heat-decomposable foaming agent and 0.01 to 30 parts by weight of a crosslinking agent are mixed with 0 parts by weight, or after being mixed, the mixture is heated to a temperature equal to or higher than the decomposition temperature of the crosslinking agent and the blowing agent. It can be manufactured.

The expansion ratio is 1.02 times or more and 50 times or less. If the expansion ratio is less than 1.02 times, the characteristics as a foam will not be produced, and if the expansion ratio exceeds 50 times, the cells will be continuous and the surface unevenness will become large, and it will not be a practical foam.

The kneading method for dispersing the crosslinking agent and the foaming agent can be carried out by any known method, but preferably kneading is carried out by a roll or an extruder. The kneading temperature needs to be equal to or higher than the melting point of the aliphatic polyester and equal to or lower than the decomposition temperature of the crosslinking agent, and is 100 ° C to 270 ° C, and more preferably 100 ° C to 250 ° C.

Further, in the present invention, ionizing radiation such as electron beam, β ray or gamma ray can be used for crosslinking. In the case of crosslinking by radiation, in order to prevent the deterioration of the resin, under N ₂ atmosphere, from 1 Mrad to 50
Irradiate Mrad radiation. If it is less than 1 Mrad, the crosslinking reaction does not occur, and if it is 50 Mrad or more, the deterioration of the resin becomes severe. The thickness of the resin is preferably 1 mm or less, more preferably 5 mm or less. If the thickness exceeds 1 mm, the radiation does not reach the inside, so that the bubbles inside are coarse and non-uniform during foaming.

[0039]

EXAMPLES The present invention will be described below with reference to examples and comparative examples. (Example 1) After purging a 700 L reactor with nitrogen,
1,4-butanediol 183 kg, succinic acid 224 k
I charged g. The temperature is raised under a nitrogen stream to 192-22
3.5 hours at 0 ° C, 20 to 2 mm after stopping nitrogen further
The esterification reaction by dehydration condensation was carried out under a reduced pressure of Hg for 3.5 hours. The sample collected has an acid value of 9.
It was 2 mg / g, the number average molecular weight (Mn) was 5,160, and the weight average molecular weight (Mw) was 10,670. Subsequently, 34 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 215
5.5 at -220 ° C. under reduced pressure of 15-0.2 mmHg
The deglycol reaction was performed for a period of time. The sample collected had a number average molecular weight (Mn) of 16,800 and a weight average molecular weight (Mw) of 43,600. The yield of this polyester (A1) was 339 kg when condensed water was removed.

5.42 kg of hexamethylene diisocyanate was added to a reactor containing 339 kg of polyester (A1), and a coupling reaction was carried out at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, Irganox 1010 as an antioxidant
(Manufactured by Ciba Geigy Co., Ltd.) and 1.70 kg of calcium stearate as a lubricant were added,
Stirring was continued for another 30 minutes. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. After vacuum drying at 90 ° C. for 6 hours, the yield of polyester (B1) was 300 kg.

The polyester (B1) thus obtained is a slightly ivory white waxy crystal having a melting point of 110.
C., the number average molecular weight (Mn) is 35,500, the weight average molecular weight (Mw) is 170,000, the MFR (190 ° C.) is 1.0 g / 10 minutes, the viscosity of a 10% solution of orthochlorophenol is 230 poises, Temperature 190 ℃, shear rate 10
The melt viscosity at ⁰ sec ⁻¹ was 1.5 × 10 ⁴ poise. The average molecular weight is measured by Shodex GPC.
System-11 (Showa Denko KK gel chromatography), solvent of CF ₃ COONa HFIPA5m
mol solution, concentration: 0.1% by weight, calibration curve: Showa Denko KK-made PMMA standard sample ShodexStand
ard M-75.

100 parts by weight of polyester (B1) and 0.5 parts by weight of talc were kneaded at 160 ° C. in a tandem extruder consisting of a 40φ extruder and a 50φ extruder, and per 100 parts by weight of the mixed resin from the middle of the cylinder of the extruder. Dichlorodifluoromethane is pressed in at a ratio of 24 parts by weight, and the diameter is 60 m.
From a circular die with mφ and a gap of 0.6 mm,
A foam was manufactured by extrusion into the atmosphere at a die temperature of 110 ° C. As a result, the expansion ratio is 40 times and the bubble diameter is 0.4 mmφ.
A foam having a diameter of ˜0.6 mm was obtained. 5 this foam in the soil
When it had been buried for a month, the foam had decomposed and changed into small pieces.

Example 2 A 700 L reactor was purged with nitrogen, and then 177 kg of 1,4-butanediol, 198 kg of succinic acid, and 25 kg of adipic acid were charged. The temperature is raised under a nitrogen stream, and the temperature is set to 190 to 210 ° C for 3.5 hours.
Further, nitrogen is stopped, and under reduced pressure of 20 to 2 mmHg, 3.
The esterification reaction by dehydration condensation was performed for 5 hours. The sample collected had an acid value of 9.6 mg / g, a number average molecular weight (Mn) of 6,100, and a weight average molecular weight (M
w) was 12,200. Subsequently, 20 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 15-
The deglycol reaction was performed for 6.5 hours under a reduced pressure of 0.2 mmHg. The collected sample has a number average molecular weight (Mn)
Is 17,300, and the weight average molecular weight (Mw) is 46,
It was 400. The yield of this polyester (A2) was 337 kg when condensed water was removed.

4.66 kg of hexamethylene diisocyanate was added to a reactor containing 333 kg of polyester (A2), and a coupling reaction was carried out at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, Irganox 1010 as an antioxidant
(Manufactured by Ciba Geigy Co., Ltd.) and 1.70 kg of calcium stearate as a lubricant were added,
Stirring was continued for another 30 minutes. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. After vacuum drying at 90 ° C. for 6 hours, the yield of polyester (B2) was 300 kg.

The polyester (B2) thus obtained is a slightly ivory white waxy crystal having a melting point of 103.
° C, number average molecular weight (Mn) is 36,000, weight average molecular weight (Mw) is 200,900, MFR (190 ° C) is 0.52 g / 10 minutes, 10% of orthochlorophenol.
Viscosity of the solution is 680 poise, temperature 190 ℃, shear rate 1
The melt viscosity at 00 sec ⁻¹ was 2.2 × 10 ⁴ poise.

100 parts by weight of polyester (B2) and 0.5 parts by weight of talc were kneaded at 160 ° C. in a tandem extruder consisting of a 40φ extruder and a 50φ extruder, and per 100 parts by weight of the mixed resin from the middle of the cylinder of the extruder. Dichlorodifluoromethane is pressed in at a ratio of 18 parts by weight, and the diameter is 60 m.
From a circular die with mφ and a gap of 0.6 mm,
A foam was manufactured by extrusion into the atmosphere at a die temperature of 90 ° C. As a result, the expansion ratio is 30 times and the bubble diameter is 0.4 mmφ.
A foam having a diameter of ˜0.6 mm was obtained. 5 this foam in the soil
After burying it for a month, it had decomposed and changed to a state where it could not withstand practical use.

(Example 3) After replacing a 700 L reactor with nitrogen, 200 kg of 1,4-butanediol, 250 kg of succinic acid and 2.8 kg of trimethylolpropane.
Was charged. Raise the temperature under a nitrogen stream to 192-220
4.5 hours at ℃, 20 to 2mmH after stopping nitrogen further
The esterification reaction by dehydration condensation was performed for 5.5 hours under a reduced pressure of g. The sample collected has an acid value of 10.
It was 4 mg / g, the number average molecular weight (Mn) was 4,900, and the weight average molecular weight (Mw) was 10,000. Then, 37 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream at atmospheric pressure. Increase the temperature to 210
8.0 at 220 ° C. under a reduced pressure of 15 to 1.0 mmHg.
The deglycol reaction was performed for a period of time. The sample collected had a number average molecular weight (Mn) of 16,900 and a weight average molecular weight (Mw) of 90,300 (Mw / Mn = 5.
4). This polyester (A3) is theoretically condensed water 7
The yield was 367 kg excluding 6 kg.

3.67 kg of hexamethylene diisocyanate was added to a reactor containing 367 kg of polyester (A3), and a coupling reaction was carried out at 160 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, Irganox 1010 as an antioxidant
(Manufactured by Ciba Geigy Co., Ltd.) and 367 g of calcium stearate as a lubricant were added, and further 30
Stirring was continued for a minute. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. After vacuum drying at 90 ° C. for 6 hours, the yield of polyester (B3) was 350 kg.

The polyester (B3) obtained was a slightly ivory-like white waxy crystal and had a melting point of 110.
C., the number average molecular weight (Mn) is 17,900, and the weight average molecular weight (Mw) is 161,500 (Mw / Mn = 9.
0), MFR (190 ° C.) was 0.21 g / 10 minutes, the temperature was 180 ° C., and the melt viscosity at a shear rate of 100 sec ⁻¹ was 2.0 × 10 ⁴ poises. Polyester (B3)
Was blended under the same conditions as in Example 1 and foam-molded to give a foaming ratio of 40 times and a cell diameter of 0.3 mmφ.
A foam having a diameter of 0.5 mm was obtained. 5 this foam in the soil
When it was buried for a month, the foam had decomposed and changed into small pieces.

(Comparative Example 1) Polyester (A1) was molded under the same conditions as in Example 1, but cells having a stable shape could not be obtained, and a foam which could be used practically was not obtained.

Comparative Example 2 An attempt was made to mold a commercially available polyester (Mn = 40,000, polyethylene terephthalate) under the same conditions as in Example 1, but a foam could not be obtained. Therefore, a biodegradability test was conducted using a polyethylene terephthalate film, which is a condensate of 13 μm of commercially available terephthalic acid with ethylene glycol, but there was almost no change in appearance, and biodegradability was not recognized.

Example 4 100 parts by weight of the polyester (B1) obtained in Example 1, 4 parts by weight of azodicarbonamide, 0.5 part by weight of zinc oxide and 0.5 part by weight of talc were used as a 40φ extruder. And a 50φ extruder were used to knead the mixture at 180 ° C., and then extruded with a T die having a width of 300 mm at a die temperature of 110 ° C. to prepare a foam. As a result, the expansion ratio is 1.8 times and the bubble diameter is 0.4 mm.
A foam of φ to 0.6 mmφ was obtained. When the foam obtained by this production method was buried in soil for 5 months, the shape of the foam was severely deformed, and changes in decomposition were observed.

Example 5 100 parts by weight of the polyester (B2) obtained in Example 2, 16 parts by weight of azodicarbonamide, 0.5 part by weight of zinc oxide and 0.5 part by weight of talc were used as a 40φ extruder. After kneading with a tandem extruder consisting of a 50φ extruder and a φφ extruder at 180 ° C., a caliber of 60 mmφ, 0.6
A foam was prepared by extruding with a circular die having a gap of mm at a die temperature of 90 ° C. As a result, the expansion ratio is 10.0 times, and the bubble diameter is 0.4 mmφ to 0.6 mmφ.
A foam of The foam obtained by this manufacturing method is added to the soil 5
After being buried for a month, the foam decreased to a level of impracticality and a change in decomposition was observed.

(Example 6) After replacing a 700 L reactor with nitrogen, 145 kg of ethylene glycol and 2 parts of succinic acid were used.
51 kg and 4.1 kg of citric acid were charged. The temperature was raised under a nitrogen stream, the esterification reaction was carried out by dehydration condensation at 190 to 210 ° C. for 3.5 hours, and further, nitrogen was stopped and the pressure was reduced at 20 to 2 mmHg for 5.5 hours. The collected sample had an acid value of 8.8 mg / g, a number average molecular weight (Mn) of 6,800, and a weight average molecular weight (Mw) of 13,500. Subsequently, 20 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream at atmospheric pressure.
Raise the temperature to 15-0.2 at a temperature of 210-220 ° C.
The deglycol reaction was performed for 4.5 hours under reduced pressure of mmHg. The sample collected has a number average molecular weight (Mn) of 3
3,400, and the weight average molecular weight (Mw) is 137,0
It was 00. The yield of this polyester (A4) was 323 kg when condensed water was removed.

3.23 kg of hexamethylene diisocyanate was added to a reactor containing 323 kg of polyester (A4), and a coupling reaction was carried out at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelation occurred. Next, Irganox 1010 as an antioxidant
1.62 kg of Ciba Geigy Co., Ltd. and 1.62 kg of calcium stearate as a lubricant are added,
Stirring was continued for another 30 minutes. This reaction product was extruded into water with an extruder and cut into pellets with a cutter. The yield of polyester (B4) after vacuum drying at 90 ° C. for 6 hours was 300 kg.

The polyester (B4) thus obtained was a slightly ivory white waxy crystal having a melting point of 96 ° C.
The number average molecular weight (Mn) is 54,000, the weight average molecular weight (Mw) is 324,000, and the MFR (190 ° C) is 1.
1 g / 10 minutes, viscosity of 10% solution of orthochlorophenol is 96 poise, temperature 190 ° C., shear rate 100 se
The melt viscosity at c ⁻¹ was 1.6 × 10 ⁴ poise. 100 parts by weight of polyester (B4), 5 parts by weight of azodicarbonamide, and 110 parts by weight of 0.5 part of zinc oxide.
Sufficiently kneading with a roll kept at ℃, 2mm thickness x 200
A plate-shaped sheet having a size of mm × 200 mm was prepared. The sheet was heated in a hot air oven at 160 ° C. for 6 minutes to prepare a foam. As a result, a foam having an expansion ratio of 8 and a cell diameter of 0.4 mmφ to 0.6 mmφ was obtained. When the foam obtained by this method was buried in soil for 5 months, the same results as in Example 4 were obtained.

Example 7 A foam was prepared by using the polyester (B3) obtained in Example 3 and compounding and extruding it in the same manner as in Example 4. As a result, a foam having a foaming ratio of 2.0 and a cell diameter of 0.4 mmφ to 0.6 mmφ was obtained. When the foam obtained by this production method was buried in soil for 5 months, the shape of the foam was severely deformed, and changes in decomposition were observed.

(Comparative Example 3) The polyester (A1) obtained in Example 1 was molded under the same conditions as in Example 4, but the surface of the molded article had large irregularities, and the cell diameters were coarse and non-uniform (cell diameters). 1 mm or more), a foam that can withstand practical use was not obtained.

Comparative Example 4 An attempt was made to mold a commercially available polyester (polyethylene terephthalate consisting of terephthalic acid having a molecular weight of 40,000 and ethylene glycol) under the same conditions as in Example 4, but a foam could not be obtained. . Therefore, a biodegradability test was conducted using a polyethylene terephthalate film, which is a 13 μm commercially available condensate of terephthalic acid and ethylene glycol, but there was almost no change in appearance and no biodegradability was observed.

(Example 8) 100 parts by weight of the polyester (B1) obtained in Example 1, 5 parts by weight of azodicarbonamide and 0.8 parts by weight of dicumyl peroxide were kneaded at 120 ° C in an extruder. A sheet having a width of 300 mm and a thickness of 2 mm was prepared by extruding with a T-die. Further, this sheet was placed in a hot air oven adjusted to 200 ° C. for 5 minutes to prepare a foam. This gives a foaming ratio of 1
A foam having 0 times the bubble diameter of 0.4 mmφ to 0.6 mmφ was obtained. When the foam obtained by this production method was buried in soil for 5 months, the shape of the foam was severely deformed, and changes in decomposition were observed.

Example 9 100 parts by weight of the polyester (B2) obtained in Example 2 and 5 parts by weight of azodicarbonamide were kneaded at 150 ° C. in an extruder and extruded with a T die to give a width of 300 mm, A sheet having a thickness of 0.5 mm was prepared. Further, an electron beam irradiator (area beam type electron beam irradiator, Curetron (EBC-200-AA2, manufactured by Nisshin High Voltage Co., Ltd.) was used on this sheet, and an electron beam of 10 Mrad was applied to both sides of the sheet under N ₂ gas atmosphere. It was irradiated and placed in a hot air oven controlled at 200 ° C. for 5 minutes to prepare a foam, whereby a foaming ratio of 10 times,
A foam having a cell diameter of 0.3 mmφ to 0.5 mmφ was obtained. When the foam obtained by this production method was buried in the soil for 5 months, the foam decreased to a level of impracticality and a change in decomposition was observed.

(Example 10) Using the polyester (B3) obtained in Example 3, compounding was carried out in the same manner as in Example 8 and extrusion was carried out to prepare a foam. As a result, the expansion ratio is 10 times and the bubble diameter is 0.4 mmφ to 0.6 mm.
A φ foam was obtained. When the foam obtained by this production method was buried in soil for 5 months, the shape of the foam was severely deformed, and changes in decomposition were observed.

(Comparative Example 5) The polyester (A1) obtained in Example 1 was molded under the same conditions as in Example 8, but the surface roughness of the molded product was large, and the cell diameter was coarse and non-uniform (cell diameter 1 mm or more), a foam that can withstand practical use was not obtained.

[0064]

The foam produced using the aliphatic polyester and the volatile foam of the present invention has biodegradability when buried in soil or the like, and has a combustion calorific value of polyethylene or polyethylene even when incinerated. It is lower than polypropylene and has excellent mechanical strength such as tensile strength and impact strength, and is useful as a cushioning material, heat insulating material, packaging material, food container, partition plate and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C08J 9/228 CFD 7310-4F // C08L 67:00 (72) Inventor Ryosuke Kamei Kawasaki City, Kanagawa Prefecture 3-2 Chidori-cho, Kawasaki-ku Akira Kawasaki Plastics Research Laboratory (72) Inventor Eiichiro Takiyama 4-12-4 Nishi-Kamakura, Kamakura-shi, Kanagawa

Claims (13)

[Claims] 1. A temperature of 190 ° C. and a shear rate of 100 sec ^−1.
The method for producing a foam, which has a melt viscosity of 1.0 × 10 ^{3 to} 1.0 × 10 ⁶ poise and a melting point of 70 to 190 ° C. and is heated and foamed using a foaming agent. 2. The method for producing a foam according to claim 1, wherein the foaming agent is a volatile foaming agent. 3. The method for producing a foam according to claim 1, wherein the foaming agent is a heat decomposition type foaming agent. 4. The method for producing a foam according to claim 1, wherein a thermally decomposable foaming agent is used as the foaming agent, and a crosslinking agent is also used. 5. The method for producing a foam according to claim 1, wherein the expansion ratio is 1.02 to 50 times. 6. The aliphatic polyester has a number average molecular weight of 1.
The method for producing a foam according to any one of claims 1 to 5, which has a urethane bond content of 30,000 or more and 0.03 to 3.0% by weight. 7. A product obtained by reacting 0.1 to 5 parts by weight of a diisocyanate with 100 parts by weight of an aliphatic polyester prepolymer having a number average molecular weight of 5,000 or more and a melting point of 60 ° C. or more. The method for producing a foam according to claim 1. 8. The number average molecular weight (Mn) of the aliphatic polyester comprising an aliphatic glycol and an aliphatic dicarboxylic acid.
8. The method for producing a foam according to claim 6 or 7, wherein the polyester has a structure in which 5,000 or more polyester prepolymers are linked via urethane bonds. 9. The aliphatic polyester is at least one polyfunctional selected from aliphatic glycols, aliphatic dicarboxylic acids and trifunctional or tetrafunctional polyhydric alcohols, oxycarboxylic acids and polycarboxylic acids or anhydrides thereof. Number average molecular weight (Mn) obtained by adding and reacting components
8. The method for producing a foam according to claim 6 or 7, wherein the polyester has a structure in which 5,000 or more polyester prepolymers are linked via urethane bonds. 10. The polyester prepolymer is selected from the group consisting of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, neopentyl glycol and 1,4-cyclohexanedimethanol as glycol units. Have units
10. The foam according to claim 8 or 9, wherein the dicarboxylic acid unit has a unit selected from the group consisting of succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and adipic anhydride. Method. 11. A polyester prepolymer as a trifunctional or tetrafunctional polyhydric alcohol as a third component,
The method for producing a foam according to claim 9, further comprising at least one selected from the group consisting of trimethylolpropane, glycerin and pentaerythritol. 12. The polyester prepolymer according to claim 9, which contains at least one selected from the group consisting of malic acid, citric acid and tartaric acid as a trifunctional or tetrafunctional oxycarboxylic acid as a third component. Method for producing foam. 13. A polyester prepolymer as a trifunctional or tetrafunctional polycarboxylic acid as a third component,
10. The composition according to claim 9, containing at least one member selected from the group consisting of trimesic acid, propanetricarboxylic acid, trimellitic acid anhydride, pyromellitic acid anhydride, benzophenonetetracarboxylic acid anhydride and cyclopentanetetracarboxylic acid anhydride. Method for producing foam.