JP2002080703A - Polyester resin composition, and material for agriculture or material for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound having excellent properties as a plasticizer of a polyester-based polymer or resin which is a biodegradable resin, especially polylactic acid, further having high safety and adding small load on environment. SOLUTION: This polyester resin composition is characterized in that the composition contains singly the acetic acid ester of diglycerol having >=50% acetylation rate or the acetic acid ester of the diglycerol, or a combination thereof with diacetylmonoacylglycerol having an >=8C fatty acid as a constituent fatty acid, as a plasticizer. The material for agriculture or the material for packaging is characterized in that the polyester resin composition is formed into a film or a sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin composition, and more particularly, to a resin composition having excellent processability and physical properties, comprising a polyester resin containing polylactic acid as a main component and a plasticizer having a specific structural formula. About.

[0002]

2. Description of the Related Art Plastic products such as polyethylene, polystyrene, polypropylene and polyvinyl chloride are
It is used in a wide variety of fields, such as food packaging, building materials and home appliances, and is indispensable in everyday life.

[0003] However, while these plastic products have the characteristic of durability, if they end up being used and become waste, they have poor durability and are inferior in nature to decompose. It has the negative effects of causing environmental destruction, such as affecting biological systems.

[0004] Biodegradable plastics have attracted attention to overcome such disadvantages of plastics. Biodegradable plastics are decomposed into low molecular compounds in a very short time by the action of enzymes produced by microorganisms living in the environment, and finally decomposed into inorganic substances such as water and carbon dioxide.

In recent years, the recycling of plastic products has been regulated by increasing awareness of environmental issues, and so-called biodegradable plastics, which can be easily decomposed in the environment along with recycling and reuse, have attracted attention.
Focusing on development. Examples of its use include agricultural materials used in the environment (for example, sheets or films used for root crop growing houses) and materials used in the food packaging field where collection is difficult (for example, food packaging films or sheets). Etc.), other packaging materials (eg, clothing, sheets or films for daily miscellaneous goods)
The use in such as is expected.

[0006] These biodegradable plastics can be roughly classified into a microbial production system, a natural product utilization system, and a chemically synthesized system. The biodegradable plastics which are currently being put into practical use include aliphatic polyesters, modified polyvinyl alcohols, and the like. It is roughly divided into modified starch and the like.

[0007] Examples of the aliphatic polyester include polybutylene succinate and polyhydroxybutyrate.
There is polylactic acid as a semi-synthetic polymer.

Polylactic acid is a crystalline thermoplastic polymer having the same tensile strength as polyethylene and the same transparency as polyethylene terephthalate. It is used for pharmaceutical sutures, etc., has high safety, and burns. In this case, the calorie burn is about 1/3 that of polyethylene, polypropylene, etc.
It does not hurt the incinerator and generates no harmful gas. In addition, due to such advantages, research and development of manufacturing methods and applied applications have recently become active, and in the future, diversification of applications and an accompanying increase in production volume are expected.

[0009] However, polylactic acid has such advantages, but its molded product is hard and its use is restricted in fields where softness is required, particularly in films and packaging materials. To improve hardness and impart softness, one method is to add a plasticizer, but to act as a plasticizer, (1) it has excellent compatibility with the polymer or resin to be plasticized. (2) plasticization efficiency is good,
(3) It is necessary to provide such a condition that the performance does not deteriorate due to volatilization, migration or bleeding after processing.

As a plasticizer for polylactic acid and a resin containing polylactic acid as a main component, triacetin (Shimadzu review, Vol.
54, no. 155 (1997.3): JP-A-6-18
No. 4147: No. 7-177826), esters of aliphatic dicarboxylic acids and / or linear molecular diols, or aliphatic polyesters containing these as a main component (Japanese Unexamined Patent Publication No. 8-199053: No. 8-245866). ), Triacetin, tribubutin or butylphthalylbutyl glycolate (JP-A-9-296103);
A glycerin derivative having an alkyl group having 1 to 10 carbon atoms (JP-A-11-323113) or a glycerin derivative having 6 to 10 carbon atoms
Although diacetyl monoacyl glycerol having 18 acyl groups (Japanese Patent Application Laid-Open No. 2000-302956) and the like are disclosed, all of them have advantages and disadvantages in performance and physical properties and cannot be said to be sufficiently satisfactory.

[0011]

DISCLOSURE OF THE INVENTION The present invention has excellent performance as a plasticizer of a polyester-based polymer or resin, particularly polylactic acid, which is a biodegradable resin, and has high safety and low environmental load. An object is to provide a small compound.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a diglycerol acetate having an acetylation ratio of 50% or more was added to a polyester resin such as a polylactic acid resin. Alternatively, they have found that the above-mentioned object can be achieved by adding the diglycerol acetate to the diglycerol acetate ester in combination with diacetylmonoacylglycerol having an aliphatic fatty acid having 8 or more carbon atoms as a constituent fatty acid, thereby completing the present invention.

That is, the present invention has the following configuration.

1. A polyester resin composition comprising a diglycerol acetate having an acetylation ratio of 50% or more as a plasticizer.

2. 2. A polyester resin composition comprising, as a plasticizer, the diglycerol acetate described in 1 above and diacetyl monoacylglycerol containing an aliphatic fatty acid having 8 or more carbon atoms as a constituent fatty acid.

3. 3. The polyester resin composition as described in 1 or 2 above, wherein the polyester resin is polylactic acid.

4. A material for agricultural use or a material for packaging, characterized by being formed into a film or sheet from the polyester resin composition described in the above item 1, 2 or 3.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail.

The polyester in the present invention is mainly intended for polylactic acid. The polylactic acid resin used does not matter in its degree of polymerization or quality. Further, not only a homopolymer of polylactic acid but also a copolymer such as glycolic acid, ε-caprolactone, trimethylene carbonate or polyethylene glycol may be used in combination. Further, within a range that does not impair the physical properties of the polylactic acid resin, cellulose acetate, polycaprolactone, polybutylene succinate,
A copolymer of polyhydroxybutyrate and valerate,
Other biodegradable polymers such as chitin, chitosan or starch may be blended.

The plasticizer used in the present invention may be diglycerol acetate alone having an acetylation ratio of 50% or more, or a mixture of the diglycerol acetate and diacetyl monoacylglycerol containing an aliphatic fatty acid having 8 or more carbon atoms as a constituent fatty acid. It is.

The diglycerol acetate ester used in the present invention is usually a simple method for producing acetyl by reacting diglycerol with acetic anhydride to remove acetic acid as a by-product. It does not do. The diglycerol acetate having an acetylation ratio of 50% or more used in the present invention can be used alone or as a mixture of diester, triester or tetraester.

The aliphatic fatty acids constituting the diacetylmonoacylglycerol used in the present invention include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, erucic acid and diethylhexyl. A single or mixture of fatty acids having 8 or more carbon atoms such as acids can be used. Diacetyl monoacyl glycerol is a reaction between a reaction monoglyceride or distilled monoglyceride and acetic anhydride obtained by a known method such as an esterification reaction between glycerol and a fatty acid or a transesterification reaction between glycerol and a fatty acid alkyl ester or a triglyceride such as an oil or fat, Alternatively, it can be obtained by a method such as transesterification between triglyceride and triacetin, but the method is not particularly limited.

These diacetylmonoacylglycerols are effective as a plasticizer for the polyester resin, but have poor compatibility with the resin and are liable to bleed. Particularly, such as palmitic acid and stearic acid having a high melting point. The tendency is stronger in esters of saturated fatty acids having a large number of carbon atoms. Conversely, an ester of a fatty acid having 7 or less carbon atoms has an excellent effect as a plasticizer, but has disadvantages such as high volatility due to heating during processing. Therefore, as the fatty acid constituting the diacetylmonoacylglycerol used in the present invention, caprylic acid, capric acid, lauric acid, oleic acid, erucic acid, etc., having a carbon number of 8 or more and a low melting point are preferable, and among them, oxidation stability is considered. Then, the saturated fatty acids caprylic acid, capric acid and lauric acid are more preferred.

The use of these diacetyl monoacylglycerols alone has the disadvantage that bleeding tends to occur in the processed polyester resin product, but the combined use of the above diglycerol acetate suppresses the bleeding, The problem of the use of diacetyl monoacylglycerol is improved. When diglycerol acetate and diacetyl monoacylglycerol are used in combination, bleed is suppressed by adjusting the mixing ratio of both components to 10 mass% or more of diglycerol acetate.

In the present invention, the amount of the plasticizer to be added to the resin is arbitrary, but is usually 5 to 50 to the resin.
The range of mass% is preferred.

According to the present invention, (1) a diglycerol acetate having an acetylation ratio of 50% or more is contained as a plasticizer; and (2) the diglycerol acetate and an aliphatic fatty acid having 8 or more carbon atoms are used as a constituent fatty acid. And diacetyl monoacylglycerol as a plasticizer. Incidentally, a plasticizer other than the present invention may be used in combination as long as the effects of the present invention are not impaired.

The polyester resin composition of the present invention can be extruded, injected or thermoformed by using an extruder, an injection molding machine or the like used for usual plastic molding. Further, the molding temperature is preferably from 180C to 220C. When performing polymer blending, a twin-screw extruder is preferred. The resin composition melted in the extruder has a T
It is formed into a sheet or film by die, inflation and the like.

Further, a stabilizer, a lubricant, an antioxidant, a slip agent, an anti-fog agent and the like may be used in these resins, but these additives do not inhibit the effect of the plasticizer of the present invention. It is possible to use within the range.

The above-mentioned sheet or film may be used for agricultural materials (such as materials for growing houses such as root vegetables such as vinyl houses), food packaging materials (such as so-called wrap films for foods), and other materials. (For example, clothing and daily miscellaneous goods packaging materials).

[0030]

Hereinafter, the present invention will be described with reference to Examples.
The present invention is not limited to these examples.

In the evaluation test of this embodiment, "polylactic acid lacty (grade # 902)" manufactured by Shimadzu Corporation was used as the polylactic acid.
1, average molecular weight 145,000) ", and in order to prevent a decrease in molecular weight due to hydrolysis, heat drying treatment is performed at 110 ° C. for 4 hours to remove water. For each comparative example, a predetermined amount of the following test sample (described in Table 1) was blended (for example, in Example 1,
20% by mass of the following test sample-1 was added to the polylactic acid resin. In Example 8, 2% by mass of the following test sample-2 and 18% by mass of the following test sample-5 were added to the polylactic acid resin. Indicates that you have done. ), 20 using a twin screw extruder
Extruded pellets were made at 0 ° C. Using the pellets, test specimens described in the respective tests were prepared and subjected to “tensile test”, “bending test”, and “observation of bleed state” to evaluate the quality.

[Test-1] Tensile test The test was performed based on JIS K-7113. The test piece used was No. 1 test piece. The test piece was prepared from a resin composition using an injection molding machine IS55EPN manufactured by Toshiba Machine Co., Ltd. The prepared test piece was tested under the conditions of a temperature of 23 ° C and a humidity of 50% RH.
Those stored for a day were subjected to the test. As a test device, Orientec Tensilon universal tester RTC-1310
Was used. The distance between grips is 120mm, the test speed is 2
The conditions were set to 00 mm / min.

[Test-2] Bending test The test was performed based on JIS K-7203. The test piece used had a width of 12 cm and a thickness of 6 mm. The test piece was prepared from a resin composition using an injection molding machine IS55EP manufactured by Toshiba Machine Co., Ltd. The prepared test piece was at a temperature of 23 ° C and a humidity of 50% RH.
Stored for one day under the conditions described in (1) and (2). Orientec Tensilon Universal Testing Machine RT
C-1310 was used. The test speed was 3 mm / min.

[Test 3] Bleeding property A test piece having a size of 10 mm × 10 mm and a thickness of 3 cm was prepared from a press sheet, stored at a temperature of 50 ° C. and a humidity of 50% RH for one week, and bleed was observed. The results were expressed as follows. ：: No bleeding observed Δ: Slight bleeding observed ×: Many bleeds observed

[Test Sample-1] Diglycerol tetraacetate 1 mol of diglycerin was reacted with 4 mol of acetic anhydride to effect acetylation, and then acetic acid was removed by distillation under reduced pressure to obtain a test diglycerol tetraacetate product.

[Test sample-2] Diglycerol triacetate 1 mol of diglycerol was reacted with 3 mol of acetic anhydride, and treated in the same manner as in Test sample-1 to obtain a test diglycerol triacetate product.

[Test sample-3] Diglycerol diacetate 1 mol of diglycerol was reacted with 2 mol of acetic anhydride, and treated in the same manner as in Test sample-1, to obtain a diglycerol diacetate product for testing.

[Test Sample-4] Diglycerol monoacetate 1 mol of diglycerol was reacted with 1 mol of acetic anhydride and treated in the same manner as in Test sample-1 to obtain a diglycerol monoacetate product for testing.

[Test Sample-5] Glycerol diacetomonocaprylate 1 mol of glycerol and 1 mol of caprylic acid were subjected to an esterification reaction, and glycerol monocaprylate having a purity of about 90% by mass was obtained by molecular distillation. After 1 mol of the glycerol monocaprylate was reacted with 2.1 mol of acetic anhydride for acetylation, acetic acid was removed by distillation under reduced pressure to obtain a test diacetyl monocaprylate product.

[Test Sample-6] Glycerol diacetomonocaprate After the esterification reaction of 1 mol of glycerol and 1 mol of capric acid, a glycerol monocaprate ester having a purity of about 90% by mass was obtained by molecular distillation. After 1 mol of the glycerol monocaprate ester was reacted with 2.1 mol of acetic anhydride for acetylation, acetic acid was removed by distillation under reduced pressure to obtain a glycerol diacetmonocaprate product for testing.

[Test Sample-7] Glycerol diacetmonolaurate Glycerol monolaurate (Poem M-300: RIKEN Vitamin Co., monoglyceride purity: about 90% by mass) was reacted with 2.1 mol of acetic anhydride. After acetylation, acetic acid was removed by distillation under reduced pressure to obtain a glycerol diacetomonolaurate product for testing.

[Test sample-8] Di (2-ethylhexyl) phthalate: Commercial product [Test sample-9] Dibutyl phthalate: Commercial product [Test sample-10] Tributyl acetylcitrate: Commercial product [Test sample-11] Triacetin :Commercial goods

(Test Results) Table 1 shows the test and evaluation results. Note that “%” in the table is “% by mass”.

[0044]

[Table 1]

[0045]

By adding the plasticizer of the present invention,
It becomes possible to supply an eco-friendly biodegradable polyester resin product having good plasticity.

Continued on front page F-term (reference) 3E086 AB01 AD01 BA02 BA15 BB90 CA01 CA35 4F071 AA43 AC10 AH01 AH04 BA01 BB05 BB06 BB09 BC01 4J002 CF001 CF181 EH046 FD026 GA01 GG02

Claims (4)

[Claims] 1. A polyester resin composition comprising a diglycerol acetate having an acetylation ratio of 50% or more as a plasticizer. 2. A polyester resin composition comprising the diglycerol acetate according to claim 1 and diacetyl monoacylglycerol having a fatty acid having 8 or more carbon atoms as a constituent fatty acid. 3. The polyester resin composition according to claim 1, wherein the polyester is polylactic acid. 4. An agricultural material or a packaging material, which is formed from the polyester resin composition according to claim 1, 2 or 3 into a film or sheet.