JPS6026048A - drip-proof film - Google Patents

Abstract

PURPOSE:To provide a film having excellent transparency and drip-proofness persistence, by adding a mixture of a sorbitan/glycerol mixed polyol ester of a hydroxy fatty acid and a sorbitan ester of a fatty acid to a polyolefin resin and molding the mixture into a film. CONSTITUTION:A mixture of a sorbitan/glycerol mixed polyester of a 12-22C hydroxy fatty acid (A) and at least one member (B) selected from among a sor- bitan ester of a 12-22C fatty acid, a glycerol ester of said fatty acid and ethylene oxide (0.5-5mol) adduct and propylene oxide (0.5-5mol) adduct thereof, is prepd. 0.5-5wt% said mixture is added to an olefin resin such as polyethylene having a density of 0.935 or below or an ethylene/alpha-olefin copolymer. The resulting resin compsn. is molded into a film, thus obtaining the desired drip-proof film suitable for use as an agricultural film, etc.

Description

[Detailed description of the invention] The present invention relates to a polyolefin drip-proof film.

More specifically, there is a method for obtaining a polyolefin-based drip-proof film that has been imparted with drip-proof properties by adding a drip-proofing agent to a polyolefin-based resin. Related to drip-proof film suitable for packaging vegetables, fruits, etc.

Conventionally, methods for imparting drip-proof properties to films in agricultural applications and the like include applying a liquid drip-proofing agent or a solution containing a drip-proofing agent, or incorporating a drip-proofing agent into the film.

In the coating method, a drip-proofing agent is applied to the surface of a hydrophobic synthetic resin such as a polyolefin resin to impart hydrophilic properties, but although it has excellent short-term drip-proofing properties, the drip-proofing agent can be damaged by water droplets over time. Only products that are washed away and have insufficient long-term durability are obtained.

In addition, in the method of kneading a drip-proofing agent, the drip-proofing property is developed by (kneading (2)) the incorporated drip-proofing agent migrates to the resin surface (hereinafter referred to as bleed-out). Bleed-out of the drip-proof agent is required to occur appropriately during the film manufacturing process or during use of the film.

However, if the drip-proofing agent bleeds out excessively, problems such as stickiness of the film and a whitish film with decreased transparency due to the whitening phenomenon of the bleed material may occur, and if the degree of bleed-out is low, sufficient protection may not be obtained. Does not exhibit dripping properties. Furthermore, unless the drip-proof agent bleeds out appropriately during use, once the drip-proof agent is washed away by water droplets, it will not lose its drip-proof properties in a short period of time, and long-term sustainability cannot be expected.

Until now, it is well known that a method of imparting drip-proof properties to hydrophobic polyolefins by kneading fatty acid sorbitan esters, fatty acid chrycerin esters, or their ethylene oxide adducts into polyolefin resins to form a film is well known (3). Ru. However, the current situation is that these drip-proofing agents commonly bleed out, causing stickiness on the film, whitening of the bleed material, and significantly inhibiting the transparency of refilming. A satisfactory drip-proof film in which bleed and clouding are appropriately controlled has not yet been obtained.

As a result of intensive research to solve these problems, the present invention has been developed by kneading and adding a specific nonionic surfactant to polyolefin, resulting in moderate bleed-out to the film surface and excellent long-term sustainability. The present invention was achieved based on the discovery that it provides excellent drip-proof properties and, surprisingly, suppresses the bleed-whitening phenomenon in which most drip-proof agents whiten due to bleed-out.

That is, the present invention provides polyolefin resin with 12 to
Sorbitan-glycerin mixed polyol ester of hydroxy fatty acid having 22 carbon atoms and 12-22
One or a mixture of two or more of sorbitan esters, glycerin esters of fatty acids having (4) carbon atoms, or 0.5 to 5 moles of ethylene oxide or propylene oxide added thereto. The present invention relates to a film with excellent transparency and drip-proof durability formed by forming a composition containing 5 to 5% by weight of the composition.

The polyolefin resin used in the present invention is a homopolymer of α-olefin or a copolymer with a different monomer mainly composed of α-olefin, such as low density polyethylene, medium density polyethylene, high density polyethylene, Polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-hexene copolymer, ethylene-
Examples include octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl acrylate copolymer, ionomer resin, etc. 5) Among them, polyethylene and ethylene-α-olefin copolymers with a density of 0°910 to 0.935 and ethylene-vinyl acetate copolymers with a vinyl acetate content of 80” or less have good transparency and weather resistance. It is preferable as a film for agriculture and packaging in terms of price and price.

Furthermore, the vinyl acetate content is 5% by weight or more and 80% by weight.
Among these, the following ethylene-vinyl acetate copolymers are more preferable in terms of transparency, flexibility, weather resistance, etc.

The drip-proofing agent used in the present invention is a sorbitan-glycerin mixed polyol ester of a hydroxy fatty acid having 12 to 22 carbon atoms, a sorbitan ester of a fatty acid having 12 to 22 carbon atoms, a sorbitan ester of the same, or 0.0% or less of the same. One type or a mixture of two or more of ethylene oxide or propylene oxide added thereto in an amount of 5 to 5 moles is used.

The sorbitan-glycerin mixed polyol ester of hydroxy fatty acid having 12 to 22 carbon atoms exhibits almost no drip-proofing properties even if it is added alone to a polyolefin resin (6), and its production is carried out in a mixture of sorbitan and glycerin. It can be obtained by a generally known esterification reaction using a hydroxy fatty acid.

The drip-proofing agent of the present invention is a sorbitan-glycerin mixed polyol ester of hydroxy fatty acid having 12 to 22 carbon atoms (hereinafter referred to as drip-proofing agent A) and 12 to 22 carbon atoms.
One or more sorbitan esters of fatty acids having 22 carbon atoms, glycerin esters thereof, or 0.5 to 5 moles of ethylene oxide or propylene oxide adducts thereof (hereinafter referred to as drip-proofing agent B). It is characterized by being used in combination.

It is necessary that the amount of the drip-proof agent mixture added is 0.05 to 5% by weight based on the polyolefin resin. If it is less than 0.5% by weight, there will be a lot of water droplets adhering to the film surface and it will be difficult to develop drip-proof properties, and if it exceeds 5% by weight, it will be difficult to knead into polyolefin resin or the film strength will decrease ( 7) Wake up.

The mixing ratio of drip-proofing agent A and drip-proofing agent n used in the present invention is preferably A/B = 95.15 to 5/95 in terms of weight ratio.
A/IS = 70/30 to 40/60 is more preferred. The mixing ratio of drip-proofing agent A and drip-proofing agent B is A/B -9
If the drip-proofing agent A is more than 515, it is difficult to develop drip-proof properties on the film surface, whereas if the drip-proofing agent A is less than A/B = 5/95, the drip-proofing agent bleeds out to the film surface. This is undesirable because the transparency of the film is extremely deteriorated and the printability is poor.

In addition, some farmers have pointed out that films containing drip-proofing agents are undesirable because they can cause diseases in agricultural animals and reduce the amount of early morning sunlight. However, if such prevention of scarlet formation is also required, ethylene oxide adducts or propyl oxide (propylene oxide) (
8) Effective in combination with additives.

Furthermore, in the present invention, antioxidants, ultraviolet absorbers, lubricants, anti-blocking agents, etc. can be used as appropriate depending on the application, such as agricultural use or packaging. Needless to say, inorganic fillers, foaming agents, anti-rust agents, etc. are used.

The present invention is carried out by a conventional method of mixing or kneading a polyolefin resin, a drip-proofing agent, and optionally an antioxidant, an inorganic filler, an anti-blocking agent, etc. using a roll-type or Banbury-type mixer or an extruder. Then, it is formed into a film by a conventional forming method such as inflation silon processing, calendar processing, T-die processing, etc.

When the polyolefin resin film obtained by the present invention is used as a coating film for greenhouses, greenhouses, etc., or a packaging film for vegetables, fruits, etc., the transparency will not be impaired due to bleed whitening of the drip-proofing agent. It has good light transmittance (9) and excellent drip-proof properties, making it extremely useful for agricultural coating films and packaging films.

Next, the present invention will be explained with reference to Examples, but these Examples are merely illustrative and are not limited thereto.

The transparency of the films shown in Examples and Comparative Examples was measured using a haze meter, and the change in haze over time when the film was left at 23°C after processing was measured.The drip-proofing test was conducted using the following method. . Fill a 100-round beaker with water (30°C and 50°C), cover it with a sample film, and then place the beaker in a thermostatic water bath (adjusted to 30°C and 50°C), and place it in a thermostatic chamber at 3°C and 20°C, respectively. Leave it in
Observe the condition after a specified period of time, and check that the water temperature inside the sample film is 0.
℃/external temperature 3°C test was evaluated as low-temperature drip-proofing property, and test film inner water temperature 0°C/external temperature 20°C test was evaluated as high-temperature drip-proofing property.

(10) The evaluation results were expressed using the following criteria.

O: There are no small water droplets.

△D A group of small water droplets is observed in some areas.

×: Small water droplets adhere to the entire surface.

Example 1 Low density polyethylene (density: 0°921.MI: 1.
8) As a drip-proofing agent, a mixture of 0.7% by weight of sorbitan-glycerin mixed polyol hydroxystearate and 0.3% by weight of glycerin monostearate was mixed in a Banbury type mixer, and approximately It was molded into a film with a thickness of 100μ.

It was subjected to transparency and drip-proof measurements.

As shown in Table 1, excellent transparency and drip-proof properties were obtained.

Example 2 Film forming and measurements were carried out in the same manner as in Example 1 except that glycerin monostearate 1- in Example 1 was changed to sorbitan sesquipalmitate. As shown in Table 1, excellent transparency and drip-proof properties were obtained.

Example 3 Ethylene-vinyl acetate copolymer (VA content: lQwt
%, density: 0.92B, Ml: 1.5) with drip-proofing agent and 17 with 0.5% by weight of sorbitan-glycerin mixed polyol hydroxystearate and 0.5% by weight of sorbitan sesquipalmitate ethylene oxide 2 mole adduct. % and mixed wires in the same manner as in Example 1,
Inflatable film processing was performed to form a film with a thickness of approximately 50 μm, and the transparency and drip-proof properties were measured.

As shown in Table 1, excellent transparency and drip-proof properties were obtained.

Example 4 Ethylene vinyl acetate copolymer (VA content: 5 w
t%, density: 0.924, Ml: 2), a blend of sorbitan-glycerin mixed polyol, 1-0.6% by weight of hydroxystearate, and 0.4 weight Mq6 of digwaserine distearate was added as a drip-proofing agent. Cross-crossing and inflation silane film processing were performed in the same manner as in Example 1 to form a film with a thickness of about 50 μm, and the transparency and drip-proof properties were measured. The results are shown in Table 1.

Comparative Examples 1 to 3 In the formulations of Examples 1 to 3, except for the sorbitan-glycerin mixed polyol hydroxystearate used as a drip-proofing agent, glycerin monostearate 1
Axis, 1.0% by weight of sorbitan sesquipalmitate and 1.0% by weight of a 2 mole adduct of sorbitan sesquipalmitate/ethylene oxide were mixed with the resin used in Examples 1 to 3, and a film was prepared according to the same procedure. Created. As shown in Table 1, the results showed that the transparency was significantly reduced due to whitening due to bleeding of the drip-proof agent, and the high-temperature drip-proof properties were poor.

Comparative Example 4 Ethylene-vinyl acetate used in Example 4, +t-x
8 As a drip-proofing agent, 1.0% by weight of sorbitan-glyceride (13) phosphorus a-polypolyl hydroxysdarade was mixed and inflated in the same manner as in Example 1 to form a film with a thickness of approximately 50μ. It was molded and subjected to measurements of transparency and drip resistance.

The results are shown in Table 1.

(14) Takatsuki type Umehara 2-10-1 Sumitomo Within Kagaku Kogyo Co., Ltd. 309- (15 completed)

Claims (3)

[Claims] (1) A sorbitan-glycerin mixed polyol ester of a hydroxy fatty acid having 12 to 22 carbon atoms, a sorbitan ester or glycerin ester of a fatty acid having 12 to 22 carbon atoms, or 0 .5 to 5 moles of ethylene oxide or propylene oxide added
A film with excellent transparency and drip-proof durability made by forming a composition containing 0.5 to 5% by weight of a species or a mixture of two or more species. (2) The film according to claim 1, wherein the polyolefin film is polyethylene or ethylene-α-olefin copolymer having a density of 0.935 or less. (3) The film according to claim 1 (1), wherein the polyolefin film is an ethylene-vinyl acetate copolymer.