JP2006299213A - Anti-fogging agent and anti-fogging polyolefin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-fogging agent which has both environmental adaptability and effect-retaining property and to provide an anti-fogging resin film containing the agent. <P>SOLUTION: The anti-fogging agent comprises (A) a propylene glycol fatty acid ester which is an ester of propylene glycol and an 8-22C fatty acid, and (B) other polyhydric alcohol fatty acid ester. The anti-fogging resin film can be obtained by blending the anti-fogging agent into a thermoplastic resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Detailed Description of the Invention

  The present invention relates to an antifogging agent that gives a polyolefin composition a continuous antifogging effect corresponding to a wide temperature range, continuous environmental changes, and the like, and an antifogging polyolefin film containing the same. It is.

  Thermoplastic resins such as polyolefins are excellent in transparency, heat retention, weather resistance, etc., and sheets and films using these have been widely used in packaging materials and industrial materials. On the other hand, because these resins are hydrophobic, fine water droplets adhere to the surface due to changes in ambient temperature and humidity, resulting in cloudiness, invisible contents, light transmission hindered, etc. There is. Specifically, the contents cannot be seen in food packaging and the like, and not only the commercial value is reduced, but also condensation is promoted by adhering condensed water droplets to the stored food. In addition, agricultural houses have many problems such as cloudy film, poor growth of crops due to lack of sunlight, and crop diseases such as drought disease caused by drops of water from the film surface.

  In order to solve these problems, in general, a method has been adopted in which a surfactant is used to change the physical properties of the film surface to impart antifogging properties. Examples of the improvement of the surface physical properties by the surfactant include a method of applying an antifogging agent to the film surface, a method of kneading the antifogging agent in advance during film formation, and a method of using kneading and coating in combination.

  The method of applying anti-fogging agent is excellent in the initial anti-fogging property, but often has problems with its sustainability. Not suitable for required agricultural applications. On the other hand, the method of kneading the anti-fogging agent is to keep the anti-fogging property for a relatively long time by gradually bleeding the internal anti-fogging agent, so sorbitan fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, etc. Attempts have been made with various compounding formulations in use.

These attempts show a certain effect and are actually used in many films, sheets and the like, but problems remain when the use conditions are severe or when the effect needs to be sustained. For example, food packaging is required to have antifogging properties and sustainability in a low temperature range during refrigeration and freezing preservation of products with high moisture content. In addition, anti-fogging films as agricultural covering materials are increasingly required to be used for a long period of time from the viewpoint of environmental problems and economic efficiency. Conditions including drastic temperature changes are included, and there are many problems such as deterioration of the effect due to outflow of the antifogging agent because there are many cycles of moisture adhesion and drying on the film. In order to solve these problems, increasing the amount of the antifogging agent has a certain effect, but in that case, excessive blooming of the antifogging agent causes contamination of the film itself or the film surface of the active agent component. Problems such as disappearance of the anti-fogging effect due to crystallization of cannot be avoided. Among proposals as a solution, for example, in JP-A-2002-256105, an antifogging agent composition comprising a blend of a glycerin fatty acid ester, a montanic acid polyhydric alcohol ester / alkylene oxide adduct, and a montanic acid polyhydric alcohol ester. Is mentioned. However, in this attempt, no examination has been made on the moisture adhesion and drying cycle. Japanese Patent Application Laid-Open No. 2002-275308 describes an anti-fogging agent having a specific degree of esterification of polyglycerol and fatty acid ester having a high triglycerin purity, and the sustainability evaluation is evaluated for 6 months in a small house. However, it is not clear whether the study was equivalent to the extreme moisture adhesion and drying cycle expected in an environmentally severe area.
JP 2002-256105 A JP 2002-275308 A

  Thus, no antifogging agent having both environmental compatibility and effect sustainability has been found, and a compounding agent that solves this problem and gives good performance is demanded.

As a result of intensive research, the inventors have blended a certain amount of propylene glycol fatty acid ester into a system containing a polyhydric alcohol ester, so that the obtained film and sheet have a wide temperature range and a continuous environment. The present inventors have found that the antifogging effect is continuously exhibited in response to changes and the like, and have reached the present invention.
That is, the present invention excludes the propylene glycol fatty acid ester (A) from (A) propylene glycol fatty acid ester which is an esterified product of propylene glycol and a fatty acid having 8 to 22 carbon atoms, and (B) polyhydric alcohol fatty acid ester. And an antifogging polyolefin composition and antifogging film having good surface characteristics containing the antifogging agent.
A feature of the present invention is that the antifogging agent composition on the film surface can improve wettability while maintaining water resistance by blending propylene glycol fatty acid ester, and the film obtained by this effect is water-containing, There is no performance degradation even during continuous drying.

The propylene glycol fatty acid ester (A) used in the present invention is an esterified product of propylene glycol and a fatty acid having 8 to 22 carbon atoms, preferably 1.0 to 1.5 equivalents of a fatty acid having 12 to 18 carbon atoms. An esterified product is desirable. When the number of carbon atoms is less than 12, the antifogging sustainability is inferior, and when it is more than 18, the antifogging performance is inferior. On the other hand, if the degree of esterification is lower than 1.0, the film surface will be sticky, and if it is higher than 1.5, the antifogging property is inferior. Specific examples include propylene glycol laurate, propylene glycol myristate, propylene glycol palmitate, propylene glycol stearate and the like.
The ratio of the component (A) in the antifogging agent is usually 5 to 40% by weight, and the ratio of 10 to 30% by weight is most preferably used. When the ratio is lower than 5% by weight, the antifogging durability is poor, and when the ratio is higher than 40% by weight, the initial antifogging property is lowered.

    The polyhydric alcohol fatty acid ester (B) is an esterified product of a polyhydric alcohol having two or more hydroxyl groups in the molecule and a fatty acid, and the ratio in the antifogging agent is usually 50 to 95% by weight, preferably 60 ~ 90% by weight. If it is less than 50% by weight, the antifogging property is inferior. If it is more than 90% by weight, stickiness of the film, whitening, etc. may occur. Moreover, it is preferable that (B) component contains at least 1 sort (s) of sorbitan fatty acid ester, glycerol fatty acid ester, and polyglycerol fatty acid ester. These polyhydric alcohol fatty acid esters have good compatibility with propylene glycol fatty acid esters, and can make the most of their characteristic performance.

  The antifogging film of the present invention is obtained by blending 0.01 to 5% by weight of the antifogging agent of the above component with a thermoplastic resin. The thermoplastic resin is not particularly limited, but is preferably a polyolefin in terms of the antifogging performance, such as low density polyethylene, high density polyethylene, linear low density polyethylene, ethylene vinyl acetate copolymer resin, polypropylene. Etc. Moreover, the film in this invention can be manufactured by a well-known method, for example, an extrusion method (inflation, T die), a calender roll molding method, etc., The film thickness in that case becomes like this. Preferably it adjusts to 20-300 micrometers.

  When preparing the anti-fogging film of the present invention, various additives for resins usually used as necessary, for example, lubricants, antistatic agents, weather resistance improvers (ultraviolet absorbers, light stabilizers), plasticizers, oxidation You may mix | blend an inhibitor, dye, a pigment, etc. with the addition amount of the grade used normally. In addition, an inorganic compound may be used in combination as an elution regulator within a range that does not impair transparency due to the difference in crystallinity of the resin depending on the type of resin and the molding method. These effects do not impair the effects of the present invention, and the present invention does not inhibit the functions of these additives.

  In order for the antifogging film in the present invention to exert a defogging effect continuously in response to a wide temperature range, continuous environmental changes, etc., the above-mentioned propylene glycol fatty acid ester and polyhydric alcohol fatty acid ester are blended. Although it is indispensable and the detailed mechanism of its mechanism of action is unknown, it is presumed as follows.

Normal kneading type antifogging agent bleeds the hydrophilic film on the film surface, so that the moisture on the inner surface of the film is captured on the surface, and this moisture is wetted and spread on the entire surface of the film. It is preventing. However, these strongly hydrophilic components generally bleed from the film at a high speed, and due to their hydrophilic strength, they are flown in an antifogging and drying cycle. Even if it is excellent, the sustainability is often poor. In order to prevent this drawback, it is generally carried out to balance the bleed speed by blending a relatively hydrophobic component as a component to be blended with the hydrophilic component. The ingredients used to achieve this balance are themselves poor in water-capturing performance and wettability, so in the end, either hydrophilic or hydrophobic component system will be dominant, and both functions will be anti-fogging and sustaining. It is difficult. While examining various surfactants, the present inventors have found that propylene glycol fatty acid ester has excellent wettability with respect to water even though it does not have water solubility. In the present invention, by blending propylene glycol fatty acid ester with other compatible polyhydric alcohol ester, the bleed speed was controlled, and the wettability and water resistance of the bleed compound could be balanced. Thus, it is presumed that the anti-fogging effect was successfully achieved in response to a wide temperature range, continuous environmental changes, and the like.

Examples and Comparative Examples

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples unless the gist thereof is changed.

  An antifogging agent mixed in an ethylene vinyl acetate copolymer resin (vinyl acetate 5 wt%, MFR = 2.0) at the composition ratio shown in Table 3 below was mixed in an 1% extruder as an active ingredient. A 50 μm thick sheet was prepared using a die. Table 2 shows the results of performance evaluation of the obtained sheet.

(Anti-fogging evaluation method)
(1) High temperature anti-fogging property 60 ml of 50 ° C. water is put into a 100 ml glass beaker, and the mouth of the beaker is sealed and closed with a prototype film, then placed in a 50 ° C. thermostatic bath and installed at an inclination of 30 ° for 1 hour. The adhesion state of the water droplets on the inner surface of the film was visually observed and shown in a 10-step evaluation. Also, the time when the water droplets started to drop was recorded as the rise time. The shorter the rise time, the stronger the water capturing ability in the system.
{Circle around (2)} Low-temperature anti-fogging property The same measurement as the high-temperature anti-fogging property was carried out under the evaluation conditions in a low-temperature incubator with a beaker water temperature of 40 ° C. and outside air of 5 ° C.
{Circle around (3)} Antifogging durability effect Evaluation was carried out using a film stored at 20 ° C. for one week. A sample-mounted beaker was immersed horizontally in a 40 ° C. water bath, and the state of the film inner surface was observed after 1 hour. The film was immersed in 40 ° C., and a 30 ° inclination was applied. A cycle of heating from 40 ° C. for 8 hours per day to natural cooling was carried out every day, and an antifogging test was conducted 6 months later. As for low-temperature antifogging properties, a cycle of cooling at 5 ° C. for 8 hours a day to returning to room temperature was performed every day, and an antifogging test was conducted after 6 months.
Anti-fogging evaluation standard 10: No water droplets and the entire surface is wet.
9: There is no cloudiness at all, but there are very slightly repelled water droplets (10% or less).
Between 8: 7 and 9 7: There is no cloudiness, but there are repelled water droplets in some places (30% -40%).
Between 6: 5 and 7 5: Although there is no cloudiness, the repelled water is scattered as large droplets (50% to 60%).
4: Midway between 3 and 5 3: Large water droplets adhere to the entire surface, become cloudy and hardly see the contents (70% to 80%).
Between 2: 1 and 3 1: The whole is white and cloudy and the contents are completely invisible (100%).

The invention's effect

  As can be seen in the examples, by adding the antifogging agent of the present invention, a film having excellent initial antifogging properties can be obtained, and the antifogging properties can be maintained even under conditions where the change in temperature difference is long. Persisted.

Claims (5)

(A) A propylene glycol fatty acid ester which is an esterified product of propylene glycol and a fatty acid having 8 to 22 carbon atoms, and (B) a polyhydric alcohol fatty acid ester excluding the propylene glycol fatty acid ester (A). Clouding agent. The antifogging agent according to claim 1, wherein the content of the component (A) is 5 to 40% by weight and the content of the component (B) is 50 to 95% by weight. The anti-fogging agent according to claim 1, wherein the polyhydric alcohol fatty acid ester of the component (B) comprises at least one of sorbitan fatty acid ester, glycerin fatty acid ester, and polyglycerin fatty acid ester. An antifogging film comprising 0.01 to 5 parts by weight of the antifogging agent according to claim 1 as an active ingredient with respect to 100 parts by weight of a thermoplastic resin. The antifogging film according to claim 4, wherein the thermoplastic resin is a polyolefin.