Anti-blocking agent for biodegradable resin and Anti-blocking method using the same

Abstract

To provide an anti-blocking agent which imparts superior anti-blocking performance to biodegradable resins having a low glass transition temperature, and also to provide an anti-blocking method using the same.SOLUTION: An anti-blocking agent for biodegradable resin of the present invention is used for a biodegradable resin having a glass transition temperature of 25°C or less, the anti-blocking agent comprising a fatty acid ester having a molecular weight of 1500 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an antiblocking agent for biodegradable resins and an antiblocking method using the same.

Background Art

[0002] Against the backdrop of growing environmental awareness and the problem of marine plastic waste, the replacement of non-biodegradable plastics with biodegradable plastics is underway. Among them, biodegradable resins with a low glass transition temperature, such as polybutylene adipate terephthalate (PBAT), have excellent biodegradability, mechanical properties, and are being actively considered as alternatives for various applications, including agricultural use, films, sheets, plates, etc. for packaging materials, from the perspective of supply.

[0003] On the other hand, biodegradable resins such as PBAT have problems in that they are prone to blocking during processing or product use due to their chemical structure and low glass transition temperature, resulting in poor handling properties and difficulty in use. There is a need to develop agents with excellent antiblocking performance.

[0004] Conventionally, there are also technologies that add erucic acid amide to biodegradable resins to impart antiblocking performance, but this only imparts surface lubricity. Antiblocking prevention involves not only surface lubricity but also antiblocking prevention by static electricity, that is, antistatic properties, in a complex manner. However, erucic acid amide cannot be expected to impart antistatic properties, and the effect of imparting lubricity itself is also not sufficient.

[0005] To improve the performance of plastics, methods such as kneading or coating various surfactants as resin additives into plastics are widely known. For example, in Patent Documents 1 and 2, glycerin fatty acid esters or polyglycerin fatty acid esters are added to improve antistatic properties, but the target resins are limited to amorphous polyester resins that do not have biodegradability and have a high glass transition temperature, and there is no effect of imparting antiblocking properties.

[0006] Patent Document 3 targets various thermoplastic resins such as aromatic polyester resins, aliphatic polyester resins, polyolefin resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, polyvinyl alcohol resins, ethylene-vinyl acetate copolymer resins, etc., without considering biodegradability or glass transition temperature, and it is said that antistatic properties and antiblocking properties are imparted by a combination of an ionic surfactant and a nonionic surfactant. However, the antiblocking effect on biodegradable resins with a low glass transition temperature using fatty acid esters of a specific molecular weight was not clear.

[0007] Patent Document 4 proposes a technique of adding a fatty acid ester to a poly(3-hydroxybutyrate) resin or a polybutylene succinate resin to impart antistatic properties.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, Patent Document 4 is mainly a packaging film used for storing electronic components. Without impairing moldability and biodegradability, it examines the surface resistivity for the purpose of avoiding electrostatic breakdown of electronic components due to electric shock caused by charging, that is, heat generated by discharge, which can lead to component failure. However, the surface resistivity is 10 for dealing with this purpose. 13It is in a relatively high range near Ω / □. There is no specific disclosure regarding the effect of imparting antiblocking properties, and there has been no sustainability of antiblocking performance over a long period. Biodegradable resins with a low glass transition temperature have strong tackiness (adhesiveness) and are prone to blocking. For example, in inflation molding, films wound into a tube shape during molding stick to each other, and in the case of films or rolls, the surfaces of the stacked films adhere to each other and are difficult to peel. Such biodegradable resins have increasing demand due to recent environmental issues, but the problem of blocking has arisen from such recent trends and has not been sufficiently studied. Under such circumstances, due to the need not for order production, etc., there has also been a demand to extend the storage period of biodegradable resin products, but there has been a problem that the antiblocking property deteriorates with long-term storage. Although there are measures such as hydrolysis stabilizers, their effects are limited, and a technology that can maintain the antiblocking performance even after long-term storage is desired.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide an antiblocking agent that imparts excellent antiblocking performance to a biodegradable resin having a low glass transition temperature and an antiblocking method using the same.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above problems, the present inventors have found that by using a fatty acid ester having a molecular weight in a specific range, excellent antiblocking performance can be imparted to a biodegradable resin having a low glass transition temperature, and have completed the present invention. That is, the antiblocking agent for a biodegradable resin of the present invention is an antiblocking agent used for a biodegradable resin having a glass transition temperature of 25°C or lower, and is characterized by containing a fatty acid ester having a molecular weight of 1500 or less. The antiblocking method for a biodegradable resin of the present invention is characterized by preventing the blocking of a resin material containing a biodegradable resin having a glass transition temperature of 25°C or lower using the antiblocking agent for the biodegradable resin.

Effects of the Invention

[0012] According to the present invention, it is possible to impart anti-blocking performance during processing or product use of a biodegradable resin having a low glass transition temperature. Furthermore, the anti-blocking performance can be maintained over a long period of time. These effects are remarkable and exceed the effects that those skilled in the art could have predicted from the configuration of the present invention.

Mode for Carrying Out the Invention

[0013] Hereinafter, the mode for carrying out the present invention will be specifically described. 1. Anti-blocking agent for biodegradable resin The anti-blocking agent for a biodegradable resin of the present invention is an anti-blocking agent used for a biodegradable resin having a glass transition temperature of 25°C or lower, and essentially contains a fatty acid ester having a molecular weight of 1500 or less.

[0014] (Fatty acid ester) In the anti-blocking agent for biodegradable resins of the present invention, the fatty acid ester is not particularly limited as long as its molecular weight is 1500 or less. The fatty acid may be a broad sense one including organic acids, but a monovalent carboxylic acid having a carboxy group in the hydrocarbon chain is preferred. The hydrocarbon may be linear or branched, saturated or unsaturated, and examples thereof include linear fatty acids having 12 to 18 carbon atoms. The alcohol is not particularly limited, and polyhydric alcohols and the like can be used. Specifically, for example, glycerin fatty acid esters (monoglycerin fatty acid esters, diglycerin fatty acid esters, polyglycerin fatty acid esters, organic acid monoglycerides (such as succinic acid fatty acid monoglycerides, citric acid fatty acid monoglycerides, diacetyl tartaric acid fatty acid monoglycerides, etc.)), sucrose fatty acid esters, sorbitan fatty acid esters, ethylene glycol fatty acid esters, propylene glycol fatty acid esters, castor oil fatty acid esters, hydrogenated castor oil fatty acid esters, pyroglutamic acid glyceryl fatty acids, polyoxyethylene fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene hydrogenated castor oil fatty acid esters, polyoxyethylene hydrogenated castor oil pyroglutamic acid fatty acid diesters, polyoxyethylene glyceryl pyroglutamic acid fatty acid diesters, etc. can be mentioned.

[0015] Among these, from the viewpoint of anti-blocking property, monoglycerin fatty acid esters, diglycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters are preferred, monoglycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters are more preferred, and polyglycerin fatty acid esters are even more preferred. These may be used alone or in combination of two or more.

[0016] The molecular weight of the fatty acid ester is 1500 or less, but from the viewpoint of the persistence of the anti-blocking effect over a long period and the bleeding property to the surface, 300 to 1000 is preferred, and 400 to 900 is more preferred.

[0017] When the fatty acid ester has a molecular weight distribution, the molecular weight of the main component shall be used. For the main component, in the case of a product, the indication specified by the product as its name shall be referred to. When the distribution is wide or it is difficult to identify the main component, the weight average molecular weight shall be referred to. Here, the weight average molecular weight can be measured, for example, by gel permeation chromatography (GPC) by comparing with a standard substance with a known molecular weight.

[0018] From the viewpoints of imparting hydrophilic effect during bleeding and further preventing blocking, the HLB of the fatty acid ester is preferably 3 or more, more preferably 3 to 16, still more preferably 4 to 15, and particularly preferably 6 to 14.

[0019] HLB can be determined by the Griffin method.

[0020] From the viewpoints of bleed-out property and blocking prevention property, the number of carbon atoms of the fatty acid ester is preferably 10 to 20, and more preferably 12 to 18. Also, from the viewpoints of bleed-out property and the persistence of the blocking prevention effect over a long period, the degree of polymerization of glycerin in the fatty acid ester is preferably 1 to 10, and more preferably 2 to 9.

[0021] (Biodegradable resin) In the blocking prevention agent for the biodegradable resin of the present invention, the biodegradable resin is not particularly limited as long as its glass transition temperature is 25°C or lower, and it is completely consumed by microorganisms and produces only natural by-products (such as carbon dioxide, methane, water, biomass, etc.). In particular, when used, it maintains the same properties and functions as conventional plastics, and after use, it is biodegradable by the action of microorganisms in nature and is finally completely decomposed into water and carbon dioxide.

[0022] The biodegradable resin may be a chemically synthesized type or a microbially produced type. Examples of the chemically synthesized type include polybutylene succinate resins using succinic acid and 1,4-butanediol as main raw material monomers, polyethylene succinate resins using succinic acid and ethylene glycol as main raw material monomers, polybutylene adipate resins using adipic acid and 1,4-butanediol as main raw material monomers, polycaprolactone resins using ε-caprolactone as a main raw material monomer, and the like. Examples of the microbially produced type include polyhydroxyalkanoate resins using hydroxyalkanoic acid as a main raw material monomer, and the like. These may be used alone or in combination of two or more.

[0023] Examples of the polybutylene succinate resin include polybutylene succinate, polybutylene succinate adipate, and the like. Examples of the polyethylene succinate resin include polyethylene succinate, polyethylene terephthalate succinate, and the like. Examples of the polybutylene adipate resin include polybutylene adipate, polybutylene adipate terephthalate, and the like. Examples of the polycaprolactone resin include polycaprolactone, copolymers of caprolactone and other hydroxycarboxylic acids, and the like. Examples of the polyhydroxyalkanoate resin include polyhydroxybutyrate, copolymers of hydroxybutyrate and other hydroxycarboxylic acids, and the like.

[0024] The glass transition temperature of the biodegradable resin is 25°C or lower, but from the viewpoints of the flexibility of the resin and the bleed-out property of the additive, 10°C or lower is preferable, and 0°C or lower is more preferable. The lower limit is not particularly limited, but from the viewpoint of use, -100°C or higher is preferable, and -60°C or higher is more preferable.

[0025] In the present invention, the glass transition temperature Tg represents the temperature of the state change between the rubbery state and the glassy state in the amorphous portion of the resin. The measurement of the glass transition temperature Tg is performed using a differential scanning calorimeter (DSC). Specifically, approximately 5 mg of the sample to be measured is weighed, and the temperature is repeatedly increased and decreased from -100°C to 200°C under a nitrogen atmosphere at a temperature increase / decrease rate of 10°C / min. The glass transition temperature Tg is determined from the DSC curve obtained during the second heating.

[0026] In the present invention, the biodegradable resin having a glass transition temperature of 25°C or lower may be a resin material composed only of the biodegradable resin (A) having a glass transition temperature of 25°C or lower, or may be a resin material containing the biodegradable resin (A) having a glass transition temperature of 25°C or lower and having biodegradability as a whole resin. In this case, a biodegradable resin (B) having a glass transition temperature exceeding 25°C may be used in combination as a blend.

[0027] Examples of the biodegradable resin (B) having a glass transition temperature exceeding 25°C include polylactic acid, polyglycolic acid, polyvinyl alcohol, and the like.

[0028] From the viewpoint of preventing blocking, the mass ratio of the biodegradable resin (A) having a glass transition temperature of 25°C or lower to the total amount of the biodegradable resins (A) and (B) is preferably such that the value of [(mass % of (A) / 100) × (glass transition temperature of (A)) + (mass % of (B) / 100) × (glass transition temperature of (B))] is 25°C or lower, and more preferably 15°C or lower.

[0029] From the viewpoints of stickiness on the resin surface after molding and moldability, the addition amount of the blocking preventive agent for the biodegradable resin of the present invention is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the biodegradable resin. Here, 100 parts by mass of the biodegradable resin means the total amount thereof when the biodegradable resins (A) and (B) are used in combination.

[0030] In the resin material to which the anti-blocking agent for biodegradable resins of the present invention is added, within a range not impairing the effects of the present invention, in addition to the biodegradable resins (A) and (B), other components may be added. Examples of other components include known additives for improving the properties of the resin material.

[0031] (Use of resin material) The use of the resin material using the anti-blocking agent for biodegradable resins of the present invention is not particularly limited, but examples include uses where the surfaces overlap during storage or use. For example, films for agricultural and packaging materials (especially multi-films used for soil heat preservation, moisture retention, ground temperature increase, weed prevention, etc.), sheets, plates, injection molded products, etc. Among these, films, sheets, and plates are preferred, and films and sheets are more preferred, from the viewpoint of effectively exhibiting the anti-blocking performance.

[0032] 2. Anti-blocking method The anti-blocking method for biodegradable resins of the present invention prevents the blocking of a resin material containing a biodegradable resin having a glass transition temperature of 25°C or lower, using the anti-blocking agent for biodegradable resins of the present invention described above.

[0033] Specific methods for using the anti-blocking agent for biodegradable resins of the present invention are not particularly limited, and examples include a method of kneading into the resin material, a method of coating on the surface of the resin material, etc. Among these, the method of kneading into the resin material is preferred from the viewpoints of simplicity and specifically exerting the anti-blocking effect on biodegradable resins having a glass transition temperature of 25°C or lower. According to the method of the present invention, the lubricity and antistatic property imparted by the anti-blocking agent for biodegradable resins of the present invention act in combination, and in the case of films or rolls, it is possible to prevent the sticking of the stacked films, that is, the surfaces adhere to each other and are difficult to peel off. Furthermore, the anti-blocking performance hardly decreases even during a long storage period, and the anti-blocking performance can be maintained over a long period.

[0034] The surface resistivity (Rs) and the surface kinetic friction coefficient (μk) of the resin material using the anti-blocking agent for the biodegradable resin of the present invention are not particularly limited. However, from the viewpoint of exhibiting anti-blocking performance, the surface resistivity (Rs) is Rs < 10 13 is preferable, and Rs ≤ 10 12 is more preferable. The surface kinetic friction coefficient (μk) is preferably μk < 0.3, and more preferably μk ≤ 0.1. Here, the measurement methods of these are referred to the description in the Examples section.

Examples

[0035] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. Example 1 To 100 parts by mass of polybutylene adipate terephthalate (manufactured by BASF, trade name: ECOFLEX), 1 part by mass of polyglyceryl-6 monooleate was added as an additive, and these were melt-mixed in a high-temperature dryer at about 90 °C, kneaded in an extruder, then extruded from the extruder at 160 °C, and processed into pellets. Using these pellets, a plate having a length of 65 mm, a width of 45 mm, and a thickness of 2 mm was molded at about 185 °C with an injection molding machine. The antistatic property and lubricity of this plate were evaluated. Also, in the same manner as above, to 100 parts by mass of polybutylene adipate terephthalate, 1 part by mass of polyglyceryl-6 monooleate was added as an additive, and these were melt-mixed, kneaded in an extruder, and then extruded from an extruder for film molding to obtain a film with a thickness of 50 μm. This film was cut out into a 5 cm square, and the anti-blocking property was evaluated.

[0036] Example 2 The additive was changed to polyglyceryl-4 monolaurate, and plates and films were obtained in the same manner as in Example 1. The antistatic property and lubricity of the plates were evaluated, and the anti-blocking property of the films was evaluated.

[0037] Example 3 The additive was changed to polyglyceryl-10 monomyristate, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0038] Example 4 The additive was changed to glyceryl monostearate, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0039] Example 5 The additive was changed to sorbitan stearate, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0040] Example 6 The additive was changed to sucrose stearate, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0041] Example 7 100 parts by mass of polycaprolactone was used instead of 100 parts by mass of polybutylene adipate terephthalate. Plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0042] Comparative Example 1 No additive was added, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0043] Comparative Example 2 The additive was changed to polyglyceryl-4 pentastearate, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0044] Comparative Example 3 The additive was changed to erucic acid amide, and plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0045] Comparative Example 4 100 parts by mass of polylactic acid was used instead of 100 parts by mass of polybutylene adipate terephthalate. Plates and films were obtained in the same manner as in Example 1 except for this. The antistatic property and lubricity of the plates were evaluated, and the antiblocking property of the films was evaluated.

[0046] The following evaluations were conducted for the examples and comparative examples. [Antistatic property] Each plate obtained in the examples and comparative examples was conditioned for 1 day or more in an environment of a temperature of 25°C and a humidity of 40% R.H., and then the surface resistivity (Rs) was measured using a super high insulation meter SM-8220 type (manufactured by Hioki E.E. Corporation). Also, as an evaluation over time, the surface resistivity (Rs) was measured again for the same plates conditioned for 3 months in the same environment. The evaluation was made based on the following criteria from the surface resistivity (Rs). Evaluation criteria ◎: Rs ≦ 10 12 〇: 10 < Rs < 10 12 <Rs<10 13 ×: 10 ≦ Rs 13 ≦Rs

[0047] [Lubricity] Each plate obtained in the examples and comparative examples was conditioned for at least one day in an environment with a temperature of 25°C and a humidity of 40% R.H., and then the dynamic coefficient of friction (μk) of the surface was measured using a tribogear TYPE-40 (manufactured by Shin-Toyo Kagaku Co., Ltd.) friction and wear tester. A metal ball (made of SUS93) was brought into contact with the plate, and the measurement was carried out under the conditions of a vertical load of 200 g, constant load measurement (only on the forward stroke), a moving distance of 30.0 mm, and a moving speed of 100 mm / min. Also, as an evaluation over time, the surface dynamic coefficient of friction (μk) was measured again for the same plates conditioned for 3 months in the same environment. The evaluation was based on the following criteria from the surface dynamic coefficient of friction (μk). Evaluation Criteria ◎: μk ≦ 0.1 〇: 0.1 < μk < 0.3 ×: 0.3 ≦ μk

[0048] [Anti-blocking Property] Each film obtained in the examples and comparative examples was conditioned for at least one day in an environment with a temperature of 25°C and a humidity of 40% R.H., and then, with two films stacked, a load of 200 g / cm 3 was applied. After standing for at least one day, the peelability when only the upper film was lifted was evaluated according to the following criteria. Evaluation Criteria ◎: The lower film does not lift, and the two films are easily peeled off. 〇: The lower film lifts, but peels off within 5 seconds. ×: The two films remain stuck, and the film does not fall even after more than 5 seconds.

[0049] The results of the above evaluations are shown in Table 1.

[0050]

Table 1

[0051] Next, the amount of additive added to the resin was changed, and the amount of additive added was evaluated based on the moldability in an injection molding machine. Example 1 obtained a plate as described above. Examples 8 and 9 are as follows.

[0052] Example 8 The addition amount of the additive was changed to 0.1 part by mass with respect to 100 parts by mass of the resin (polybutylene adipate terephthalate), and a plate was obtained in the same manner as in Example 1 except for this. Example 9 The addition amount of the additive was changed to 10 parts by mass with respect to 100 parts by mass of the resin (polybutylene adipate terephthalate), and a plate was obtained in the same manner as in Example 1 except for this.

[0053] [Moldability Evaluation] The moldability when the plate was molded by an injection molding machine was evaluated according to the following criteria. Evaluation Criteria 〇: It could be molded without problems. △: There was slip or stickiness in the injection molding machine, and it could not be molded well.

[0054] The results of the above evaluation are shown in Table 2.

[0055]

Table 2

Claims

Claim 1 An antiblocking agent used for a biodegradable resin having a glass transition temperature of 25°C or lower, The antiblocking agent for a biodegradable resin, comprising a fatty acid ester having a molecular weight of 1500 or lower. Claim 2 The antiblocking agent for a biodegradable resin according to claim 1, wherein the fatty acid ester has a molecular weight of 300 to 1000. Claim 3 The antiblocking agent for a biodegradable resin according to claim 1, wherein the fatty acid ester contains at least one selected from monoglycerin fatty acid ester, diglycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, and sucrose fatty acid ester. Claim 4 The antiblocking agent for a biodegradable resin according to claim 1, wherein the HLB of the fatty acid ester is 3 or higher. Claim 5 An antiblocking method for preventing blocking of a resin material containing a biodegradable resin having a glass transition temperature of 25°C or lower, using the antiblocking agent for a biodegradable resin according to any one of claims 1 to 4.

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