JP2002069186A - Ultra-low density polysuccinimide copolymer foam and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable polysuccinimide copolymer foam having sufficient strength in spite of being ultra-low density, and to provide a method of producing the foam. SOLUTION: The polymer is produced by polymerizing aspartic acid expressed by structural formula (1), a dicarboxylic acid expressed by general formula (2), where D represents an organic group having 2 to 5 carbons containing at least one polymerizable carbon-carbon double bond, and a diamine expressed by general formula (3), where R1 represents a bivalent aliphatic or aromatic group having 1 to 20 carbons, which has a density in the range of 0.002 to 0.02 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a low-density foam of a polysuccinimide copolymer.

[0002]

2. Description of the Related Art A polysuccinimide represented by the following structural formula (4) is hydrolyzed into a polyaspartic acid represented by a structural formula (5) or (6). It is useful as a water absorbing agent, a chelating agent, a scale inhibitor, a builder for detergents, a dispersant, a humectant, and an additive for fertilizers.

[0003]

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[0004] Polysuccinimide production methods include:
For example, JP-B-48-20638, JP-B-52-8-8
873, JP-A-6-211982, JP-A-7-126379, JP-A-7-165910, JP-A-9-143265, JP-A-10-72
No. 524, US Pat. No. 5,484,945, USP
No. 5,380,817 discloses a method for producing aspartic acid or a hydrochloride thereof by heating and dehydrating and condensing it in the presence of a catalyst such as 85% phosphoric acid. -211983,
JP-A-6-211984, JP-A-6-25650
4, JP-A-6-298930, JP-A-9-1989
JP-A-31193 and JP-A-9-309952 disclose ammonia by reacting maleic anhydride with water using water as a solvent to form maleamic acid or ammonium maleate, which is heated and dehydrated and condensed. A method for doing so is disclosed.

[0005] However, the polysuccinimide obtained by the above-mentioned method, when formed into a film or sheet, did not have a strength that can withstand practical use. JP-A-10-287754
JP-A-10-292444 discloses a technique of casting a slurry containing a cross-linked polysuccinimide and drying it to obtain a film. was there. Furthermore, JP-A-9-48919, JP-A-9-165446, JP-A-10-7778, JP-A-10-139
880 and JP-A-10-168326,
A method for producing a resin having mechanical strength, which is difficult to exhibit by polysuccinimide alone by copolymerizing a thermoplastic resin or a monomer other than an amino acid with polysuccinimide, is disclosed. There are problems that the decomposability is reduced and the performance such as heat resistance is reduced. In addition, Japanese Patent Application Laid-Open
235372 discloses a technique for producing a film having mechanical strength by copolymerizing aspartic acid and other amino acids in the presence of a polyfunctional polymer. However, in this method, it is necessary to use a highly toxic polar solvent such as N, N-dimethylformamide or N, N-dimethylacetamide, which is not preferable in terms of environmental health and safety.

With respect to foams containing the structure of polysuccinimide and / or polyamino acid, see JP-A-10-777.
No. 8 discloses a foam obtained by adding a small amount of aspartic acid to lactic acid or the like and copolymerizing it, but it cannot be used at a high temperature because the ester structure has a main structure. . Also, Japanese Patent Application Laid-Open No. H10-168326 discloses a foam in which a thermoplastic resin contains polysuccinimide and / or a polyamino acid, but the thermoplastic resin does not have biodegradability. In some cases, it did not completely biodegrade and could not be used at high temperatures.

On the other hand, a low-density foam requires only a small amount of resin and improves heat insulation performance and sound insulation performance. Therefore, heat insulation materials, sound insulation materials, sound absorption materials, cushioning materials for automobiles and furniture, shock absorbing materials, etc. There is a strong demand in the manufacturing field. However, it has been difficult to produce a very low-density foam of about 0.005 g / cm ³ while maintaining the denseness of the cell structure by foam molding of a thermoplastic resin that is frequently used. For example, US Pat. No. 3,379,802, US Pat.
The polyethylene foam disclosed in the publication No. 766099 has a minimum density of 1.68 pcf (0.027 g / cm ³ ).
And JP-A-6-184347, JP-T-2000
The polyolefin foam disclosed in JP-A-502402 had a minimum density of 0.01 g / cm ³ .

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to produce a biodegradable polysuccinimide copolymer having a sufficient strength despite its extremely low density. It is an object of the present invention to provide a body and a method for producing the same.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a salt comprising a dicarboxylic acid having at least one unsaturated carbon-carbon bond in a molecule and a diamine, A polysuccinimide-based copolymer precursor aqueous solution is obtained by dissolving in water together with aspartic acid, and the precursor aqueous solution is concentrated and pulverized to form a foamable powder, which is heated and foamed, and thermally cured. As a result, it has been found that a polysuccinimide-based copolymer foam having good physical properties can be obtained, and the present invention has been achieved. That is, the present invention relates to an aspartic acid represented by the structural formula (1), a dicarboxylic acid represented by the general formula (2) (where D represents at least one polymerizable carbon-carbon double bond having 2 to 5 carbon atoms). Represents an organic group), and the general formula (3)
(Wherein R ₁ represents a divalent aliphatic group or aromatic group having 1 to 20 carbon atoms) having a density of 0.002 to 0.02 g / cm ^3. An ultra-low density polysuccinimide-based copolymer foam characterized by the following characteristics.

[0010]

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[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Polysuccinimide copolymer foam of the present invention,
Aspartic acid represented by the structural formula (1), dicarboxylic acid represented by the general formula (2) (where D represents an organic group having 2 to 5 carbon atoms having at least one polymerizable carbon-carbon double bond) And a diamine represented by the general formula (3) (wherein R ₁ represents a divalent aliphatic group or aromatic group having 1 to 20 carbon atoms).

The aspartic acid represented by the structural formula (1) used in the present invention may be an L-form alone, a D-form alone, or a mixture of L-form and D-form at an arbitrary ratio. From the viewpoint of obtaining a foam having excellent properties, it is preferable to use the L-form alone.

The dicarboxylic acids represented by formula (2) used in the present invention may be used alone or in combination of two or more. Preferred examples of such diamines include maleic acid, citraconic acid, aconitic acid, and the like,
A particularly preferred example is maleic acid.

The diamine represented by the general formula (3) used in the present invention may be an aliphatic or aromatic group-containing diamine as long as it is a primary diamine. Also, two or more diamines may be used in combination. As a preferred example of such a diamine, as an aliphatic diamine,
Ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane , 1,3-bis (aminomethyl) cyclohexane, 4,4'-methylenebis (cyclohexylamine), isophoronediamine, and the like. As aromatic diamines, m-phenylenediamine, p-phenylenediamine, 4,4 '-Diaminodiphenylmethane, 2,6-diaminopyridine, m-xylylenediamine, p-xylylenediamine, 2,2'-bis (4-aminophenyl) propane, 4,4'-diaminodiphenyl ether, 3,4- The Amino diphenyl ether,
4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 1,3-bis (p-aminophenoxybenzene), 1,3-bis (m-aminophenoxybenzene) and the like. Hexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexylamine) and m-xylylenediamine are preferred, and 4,4′-methylenebis is particularly preferred. (Cyclohexylamine). Further, these diamines may be substituted by a group which is inactive in the reaction of the present invention. Examples of these groups include an alkoxy group and a halogen.

In the present invention, a basic substance may be added for the purpose of improving the solubility of aspartic acid represented by the structural formula (1). The organic base and / or the inorganic base may be used alone, or a plurality of bases may be used in combination. Also, amines are preferably used as the organic base, and any primary, secondary, or tertiary amine may be used as long as it has a certain degree of compatibility with water. Among these, particularly preferred examples include triethylamine and 2-dimethylaminoethanol. Any inorganic base may be used as long as it dissolves in water, and particularly preferred examples include ammonia and ammonium hydroxide.

In the present invention, the molar ratio of the dicarboxylic acid represented by the general formula (3) to the dicarboxylic acid represented by the general formula (2) is preferably from 0.5 to 2.0 molar equivalents.
To 1.0 molar equivalent is particularly preferred. When the molar ratio of the diamine represented by the general formula (3) to the dicarboxylic acid represented by the general formula (2) is less than 0.5 molar equivalent, the foam tends to become brittle, and when the molar ratio is greater than 2.0 molar equivalent. Heat resistance tends to decrease.

In the present invention, the molar ratio of the aspartic acid represented by the structural formula (1) to the dicarboxylic acid represented by the general formula (2) is preferably 0.1 to 20 molar equivalents,
To 4 molar equivalents are particularly preferred. When the molar ratio of aspartic acid is less than 1 molar equivalent, the time required for biodegradation tends to increase, and when it is more than 20 molar equivalents, the mechanical strength of the obtained foam decreases.

The density of the polysuccinimide copolymer foam of the present invention is from 0.002 to 0.02 g / cm ³ . When the density is less than 0.002, strength sufficient for practical use cannot be obtained, and when the density exceeds 0.02 g / cm ³ , flexibility is lost.

Next, the method for producing the low-density foam of the present invention from the polysuccinimide copolymer precursor solution will be described in detail. The low-density foam of the present invention is an aqueous solution containing aspartic acid represented by the structural formula (1), dicarboxylic acid represented by the general formula (2), and diamine represented by the general formula (3) as a solute (hereinafter, precursor aqueous solution). ) May be concentrated and solidified, and a powder obtained by pulverizing the solidified product may be used, or the precursor aqueous solution may be heated and foamed as it is.

The aqueous precursor solution can be produced by sequentially dissolving aspartic acid represented by the structural formula (1), dicarboxylic acid represented by the general formula (2), and diamine represented by the general formula (3) in water. When aspartic acid remains undissolved, an organic base and / or an inorganic base are added to dissolve the aspartic acid. These raw materials may be added in any order.

The concentration of the aqueous precursor solution is from 20% by mass to 9%.
It is preferably 0% by mass, more preferably 40% by mass to 80% by mass. If the concentration is less than 20% by mass, the production efficiency is reduced, which is not preferable.
If it exceeds, handling tends to be difficult.

To produce powder from the aqueous precursor solution, a method of evaporating water by heating while stirring in a reactor, or a hot air dryer, a vacuum dryer, or the like, which is cast on a vat or the like, is used. The water is evaporated and concentrated, and the obtained solid is crushed to a predetermined particle size using a conventionally known crusher, mortar, agate, or the like, or a method using a known apparatus such as a spray dryer. There is.

The density of the foam of the present invention can be adjusted by adjusting the water content in the powder and the foaming temperature. The density can also be adjusted by adding a surfactant or a filler. In order to obtain the low-density foam of the present invention, the water content of the powder prepared by concentrating and pulverizing the aqueous precursor solution is preferably from 0.1 to 15%, more preferably from 1 to 15%. If the water content is less than 0.1%, the density increases due to the small amount of the foaming agent unless other foaming agent is added, and if the water content is more than 15%, a foam having a dense cell structure cannot be obtained.

Next, in order to produce the foam of the present invention from the powder thus obtained, for example, a method of extruding from an injection molding machine or an extrusion molding machine, followed by a thermal polymerization method, A method in which the pre-charged material is heated using a hot air dryer, a hot press device, a hot plate, or the like, and foamed and thermally polymerized can be used. Further, a conventionally known foam manufacturing apparatus may be used. Foaming temperature is 150 ° C
To 350 ° C, more preferably 170 ° C to 230 ° C. When the foaming temperature is lower than 150 ° C., water as a foaming agent hardly evaporates, so that the density tends to increase. Also,
If the temperature is higher than 350 ° C., the color of the obtained foam becomes dark, and thermal decomposition tends to occur partially. The temperature for thermal polymerization is 1
50 ° C to 350 ° C is preferable, and 200 ° C to 250 ° C is more preferable. If the temperature for thermal polymerization is lower than 150 ° C., the polymerization takes a long time to reduce the productivity, and if the temperature is higher than 350 ° C., the color of the obtained foam becomes deeper, and thermal decomposition tends to occur partially.

The foam of the present invention may be formed by heating the precursor aqueous solution as it is. Precursor aqueous solution 1
After foaming at a temperature of 00 ° C to 350 ° C, 150 ° C to 3 ° C
Thermal polymerization at a temperature of 50 ° C. Specifically, the precursor aqueous solution is cast on a glass plate, a silicon plate, a metal plate, or the like, and is poured into a hot air dryer or a vacuum dryer to foam at a temperature of 100 ° C to 350 ° C. Thermal polymerization at a temperature of Also in this case, if the foaming temperature is lower than 100 ° C., water as a foaming agent is less likely to evaporate, so that the density tends to increase. Tends to happen.

An organic solvent compatible with water can be added to the aqueous precursor solution as long as the effects of the present invention are not impaired. Examples of the organic solvent to be added include lower alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aprotic polar solvents such as N, N-dimethylformamide and N-methylpyrrolidone.

The precursor aqueous solution may contain, for example, an organic silane, a pigment, conductive carbon black,
Fillers such as metal particles, talc, kaolin, zeolite, mica, chemical blowing agents, physical blowing agents, air conditioners,
Other known additives such as an abrasive, a dielectric, a surfactant, and a lubricant can be added as long as the effects of the present invention are not impaired.

[0028]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Various measuring methods in the examples are as follows. Viscosity measurement: The rotational viscosity at 20 ° C. was measured using a DVL-BII type digital viscometer (B type viscometer) manufactured by Tokimec. Compressive strength, tensile strength: Measured at 20 ° C. using a model 2020 manufactured by INTESCO.

Preparation of precursor aqueous solution 1 4,4'-diaminodicyclohexylmethane 228.9
460 g of water was added to g (1.09 mol), and the mixture was stirred. When 126.3 g (1.09 mol) of maleic acid was added thereto and stirred, a uniform colorless and transparent solution was obtained. Where L
-144.8 g (1.09 mol) of aspartic acid was added, and the mixture was stirred at room temperature for 1 hour. 20 g of triethylamine
(0.20 mol), 20 g of 28% by mass ammonia water
(0.33 mol) was gradually added, and the mixture was further stirred at room temperature for 1 hour. The remaining L-aspartic acid was dissolved to obtain a colorless, transparent and uniform precursor aqueous solution 1 (solid content: 50% by mass). %). When the viscosity of this solution was measured, it was 24 mPa · s.

Preparation of Precursor Aqueous Solution 2 4,4'-Diaminodicyclohexylmethane 177.5
430 g of water was added to g (0.84 mol), followed by stirring. When 97.9 g (0.84 mol) of maleic acid was added thereto and stirred, a uniform colorless and transparent solution was obtained. Where L−
224.6 g (1.69 mol) of aspartic acid was added, and the mixture was stirred at room temperature for 1 hour. 20 g of triethylamine (0.
20 mol), 50 g of 28% by mass aqueous ammonia (0.82 m
ol) was gradually added, and the mixture was further stirred for 1 hour at room temperature. The remaining L-aspartic acid was dissolved,
A colorless, transparent and uniform precursor aqueous solution 2 was obtained (solid content concentration: 50% by mass). When the viscosity of this solution was measured, 39
mPa · s.

Example 1 The above aqueous precursor solution 1 was cast on a vat to a thickness of 5 mm.
It dried with a 40 degreeC hot-air dryer for 2 hours. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape, and was ground in a mortar to 355 μm or less. 2600P
a, It dried at 100 degreeC for 12 hours. The water content of the expandable powder thus obtained was 9%. 40 g of this expandable powder was charged into a 200 × 200 × 75 mm mold, and was heated at 180 ° C. for 30 minutes in an oven preheated to 180 ° C.
Foaming and heat curing were performed at 200 ° C. for 1 hour and at 230 ° C. for 2 hours.
The density of the foam obtained by demolding is 0.0060 g / cm.
A ^3, a compressive strength at 50% compression was 6.9 kPa. When the foam was subjected to a biodegradability test in compost at 60 ° C., it disappeared in the compost after 40 days.

Example 2 A precursor aqueous solution 2 was cast on a vat to a thickness of 5 mm,
It dried with the hot air dryer of 2 degreeC for 2 hours. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape.
It was pulverized to 55 μm or less. This powder was prepared at 2600 Pa, 1
Dry at 00 ° C. for 12 hours. The water content of the expandable powder thus obtained was 10%. This foamable powder 4
0 g is charged into a 200 × 200 × 75 mm mold, and is heated at 180 ° C. for 30 minutes in an oven preheated to 180 ° C. for 20 minutes.
Foaming and heat curing were performed at 0 ° C. for 1 hour and 230 ° C. for 2 hours. The density of the foam obtained by demolding was 0.0045 g / cm ³ , and the compressive strength at 50% compression was 4.9 kPa. When the foam was subjected to a biodegradability test at 60 ° C. in compost, it disappeared in the compost after 15 days.

Example 3 The precursor aqueous solution 1 was cast on a vat to a thickness of 5 mm,
It dried with the hot air dryer of 2 degreeC for 2 hours. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape.
It was pulverized to 55 μm or less. This powder was prepared at 2600 Pa, 1
The coating was dried at 00 ° C. for 12 hours and then at 150 ° C. under normal pressure for 3 hours. The water content of the expandable powder thus obtained was 7%. 80 g of this foamable powder is 200 × 200
180 ° C for 30 minutes, 200 ° C for 1 hour, 230 ° C in an oven preheated to 180 ° C after charging into a 75 mm mold
Foamed and heat-cured for 2 hours. The density of the foam obtained by demolding was 0.058 g / cm ³ , and the compressive strength at 50% compression was 460 kPa. When the foam was subjected to a biodegradability test in compost at 60 ° C., it disappeared in compost after 45 days.

Example 4 A precursor aqueous solution 2 was cast on a glass substrate to a thickness of 100 μm using a bar coater, dried at 50 ° C. for 30 minutes, and then dried at 80 ° C. for 30 minutes, 110 ° C. for 30 minutes, and 150 ° C. for 30 minutes. ,
Foaming and thermosetting were performed at 170 ° C. for 30 minutes, 200 ° C. for 1 hour, and 230 ° C. for 2 hours. The foam obtained by peeling from the glass substrate has a thickness of 860 μm and a density of 0.05 g / c.
m ³ and a tensile strength of 5.7 kPa. When the foam was subjected to a biodegradability test at 60 ° C. in compost, it disappeared in the compost after 15 days.

Comparative Example 1 100.0 g (0.75 mol) of L-aspartic acid was added to 100
g of water and triethylamine was added dropwise until L-aspartic acid was completely dissolved to obtain a uniform solution. The used triethylamine was 87.5 g (0.87 mol).
l). This solution was dried with a hot air dryer at 140 ° C. for 2 hours. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape, and was ground in a mortar to 355 μm or less. This powder was dried at 2600 Pa and 100 ° C. for 12 hours. The water content of the expandable powder thus obtained is 1
2%. 80 g of this foamable powder is 200 × 200
180 ° C for 30 minutes, 200 ° C for 1 hour, 230 ° C in an oven preheated to 180 ° C after charging into a 75 mm mold
Foamed and heat cured for 2 hours. Although the obtained foam had a density of 0.0041 g / cm ^3, it was fragile even if it was lightly touched by hand.

Comparative Example 2 The precursor aqueous solution 1 was cast on a vat to a thickness of 5 mm,
It dried with the hot air dryer of 2 degreeC for 2 hours. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape.
It was pulverized to 55 μm or less. This powder was prepared at 2600 Pa, 1
The coating was dried at 00 ° C. for 12 hours and then at 150 ° C. under normal pressure for 3 hours. The water content of the expandable powder thus obtained was 9%. 40 g of this foamable powder is 200 × 200
Charged in a mold of × 75mm and foamed in an oven preheated to 180 ° C for 30 minutes at 180 ° C and 1 hour at 200 ° C,
Thereafter, heat treatment was performed at 370 ° C. for 2 hours. The foam obtained by demolding had a density of 0.0070 g / cm ³ , but was black and brittle.

Comparative Example 3 The precursor aqueous solution 1 was cast on a vat to a thickness of 5 mm,
It dried for 1 hour with the hot air dryer of ° C. When the obtained concentrated solution was cooled to room temperature, it solidified in a plate shape.
It was pulverized to 55 μm or less. The water content of this powder is 17%
Met. 40 g of the foamable powder thus obtained was
Charge to a mold of 00 × 200 × 75mm and 180 ℃
Was foamed and thermally cured in a preheated oven at 180 ° C. for 30 minutes, 200 ° C. for 1 hour, and 230 ° C. for 2 hours. The foam obtained by demolding had a density of 0.015 g / cm ³ , many had a cell size exceeding 1 cm, and the cell structure was not uniform.

[0038]

As described above, the polysuccinimide-based copolymer foam of the present invention has a very low density and is biodegradable. In the manufacture of cosmetic puffs, shock absorbers, cushioning materials, heat and cold insulation materials, clothing materials, water retention materials, soil modifiers, artificial leather, sound absorbing materials, washing sponges, etc. It has excellent effects. It is also used for parts that require heat resistance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F212 AA40 AD17 AG20 AH81 UA10 UA17 UB01 UC06 UN21 4J043 PA05 PA19 PC065 QB15 QB33 RA05 RA06 RA07 RA34 SA02 SA05 SA06 SB03 TA12 TA53 TB03 UA341 UA342 UB011 UB012 UB0212 022 YA22 YA25 YA28 ZB31 ZB41

Claims (3)

[Claims] An aspartic acid represented by the structural formula (1), a dicarboxylic acid represented by the general formula (2) (where D is at least 1
Carbon number 2 having two polymerizable carbon-carbon double bonds
5 represents an organic group. ) And a diamine represented by the general formula (3) (wherein R ₁ represents a divalent aliphatic group or aromatic group having 1 to 20 carbon atoms), and has a density of 0.002 to 0.002.
An ultra-low-density polysuccinimide-based copolymer foam having a weight of 0.02 g / cm ³ . Embedded image 2. Aspartic acid represented by the structural formula (1), dicarboxylic acid represented by the general formula (2) (where D is at least 1
Carbon number 2 having two polymerizable carbon-carbon double bonds
5 represents an organic group. ) And a diamine represented by the general formula (3) (wherein R ₁ represents a divalent aliphatic or aromatic group having 1 to 20 carbon atoms) as a solute, and then concentrated to obtain a water solution. 2. An ultra-low density polysuccinimide according to claim 1, wherein the powder has a content of 0.1 to 15% by mass, and the obtained powder is foamed and thermally polymerized at a temperature of 150 to 350 [deg.] C. A method for producing a copolymer foam. 3. An aspartic acid represented by the structural formula (1), a dicarboxylic acid represented by the general formula (2), wherein D is at least 1
Carbon number 2 having two polymerizable carbon-carbon double bonds
5 represents an organic group. ) And a diamine represented by the general formula (3) (wherein R ₁ represents a divalent aliphatic group or aromatic group having 1 to 20 carbon atoms) as a solute, at 100 ° C.
The method for producing an ultra-low-density polysuccinimide-based copolymer foam according to claim 1, wherein after foaming at a temperature of 350 ° C, thermal polymerization is performed at a temperature of 150 ° C to 350 ° C.