Fruit and vegetable packaging film

Abstract

To suppress the deterioration of freshness of fruits and vegetables due to a film itself for a freshness holding bag by providing materials suitable for the packaging bag of fruits and vegetables, and to realize further retaining freshness of fruits and vegetables.SOLUTION: This invention relates to a film for a freshness holding bag of fruits and vegetables having heat sealing property using a single-layer or multi-layer plastic film as a base material, wherein a dynamic friction coefficient μ' under 40°C environment between surfaces arranged as an inner surface is 0.15 or more and 0.3 or less. In addition, an exposed amount of a medical agent that reduces the dynamic friction coefficient on the surface arranged as the inner surface is 5.0×10-3 g / m2 or more and 0.5 g / m2 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a film for a freshness-keeping bag for packaging fruits and vegetables. [Background technology]

[0002] Synthetic resin film bags are commonly used as packaging for storing and transporting fruits and vegetables. Modified Atmosphere (MA) packaging, which controls the respiration of the packaged fruits and vegetables by giving these film bags various properties and adjusting the oxygen and carbon dioxide concentrations inside the bag, is widely used to maintain the freshness of fruits and vegetables. Attempts are also being made to improve the bag-making suitability and packaging workability of the films used for this.

[0003] For example, Patent Document 1 reports that for packaging bags for fruits and vegetables, in which holes are made in the film to control the respiration of the fruits and vegetables and maintain their freshness, using a film in which the average length RSm1 of the roughness curve element on the outer surface of the bag is 80 to 550 μm suppresses curling of the film, making it easier to produce freshness-maintaining packaging bags. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6536731 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the film may come into direct contact with the fruits and vegetables, if the condition of the film surface is determined with priority given to handling during production, such as suppressing curling, there is a risk that this may actually have a negative effect on the fruits and vegetables.

[0006] Furthermore, in the hot summer months, fruits and vegetables are exposed to the outside air during shipping and reloading, which increases their respiration rate, making them prone to losing freshness even when packaged in MA. Furthermore, for leafy vegetables such as spinach, the leaves tend to adhere to the inside of the packaging bag, which can make the MA packaging less effective. For these reasons, there was a demand for a film for freshness-preserving bags that could provide even greater freshness preservation.

[0007] Therefore, the object of this invention is to provide a material suitable for packaging bags for fruits and vegetables, thereby suppressing the loss of freshness of fruits and vegetables caused by the film for the fruit and vegetable freshness-preserving bags itself, and achieving further freshness preservation of fruits and vegetables. [Means for solving the problem]

[0008] This invention is The above problem was solved by providing a film for packaging bags with heat-sealing properties, based on a single-layer or multi-layer plastic film, for use in freshness-keeping bags for fruit and vegetables, in which the dynamic friction coefficient μ' between the inner surfaces at 40°C is 0.15 or more and 0.3 or less.

[0009] If the coefficient of dynamic friction μ' of the inner surface is within the above range at temperatures expected in summer, frictional resistance between the inner surface and produce during packaging is reduced, making it less likely for quality deterioration to occur due to frictional heat or abrasions. Furthermore, leafy vegetables are less likely to stick to the bag, making it less likely for the micropores created for MA packaging to become clogged, and making it easier to achieve the expected freshness-preserving effect.

[0010] The film for fruit and vegetable freshness-keeping bags according to the present invention is The amount of the agent for reducing the dynamic friction coefficient exposed on the surface arranged as the inner surface is 5.0 × 10 -3 g / m 2 More than 0.5g / m 2 The following forms can be adopted: Here, "to be exposed" refers to the amount that appears on the surface.

[0011] In addition, the film for fruit and vegetable freshness-keeping bags according to the present invention is The haze value is 1% or more and 10% or less, and The packaging bag film having an MD width of 15 mm was stacked so that the inner surfaces were in contact with each other, and the film was subjected to a pressure of 2 kgf / cm at 150°C for 1 second. 2 When the heat seal is performed under conditions in accordance with JIS Z 0238, the seal strength is 2.0 N / 15 mm or more.

[0012] Furthermore, the film for fruit and vegetable freshness-keeping bags according to the present invention can be configured to be made of a synthetic resin film having a thickness of 15 μm or more and 60 μm or less. [Effects of the Invention]

[0013] This invention can prevent packaged fruits and vegetables from losing their freshness due to contact with the bag. Furthermore, because the fruits and vegetables are less likely to come into close contact with the inner surface of the bag, it can prevent respiratory failure of the fruits and vegetables due to close contact and also prevent a situation in which the effectiveness of MA packaging is reduced due to close contact. Furthermore, because the film can be handled without affecting manufacturing suitability, such as transport and winding, it can easily be functionalized to achieve the dynamic friction coefficient μ' described above. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to embodiments thereof. The present invention relates to a film for a fruit and vegetable freshness-keeping bag used for packaging fruit and vegetables.

[0015] The film for fruit and vegetable freshness-keeping bags according to this invention uses a single-layer or multi-layer plastic film as a base material. Polyolefins such as polyethylene and polypropylene are suitable for use as plastics, with polypropylene being particularly suitable in terms of strength and manufacturability. While there are no limitations on the type of plastic, it is necessary for the bag to have heat-sealing properties, which are necessary for bag production. It may be single-layer or multi-layer. If it is multi-layer, the layers may be bonded together with an adhesive or thermocompression bonding, or may be formed by pre-lamination by co-extrusion or the like.

[0016] The film for fruit and vegetable freshness-keeping bags according to the present invention must have a dynamic friction coefficient μ' between the inner surfaces of the film at 40°C, which must be between 0.15 and 0.3. If the coefficient exceeds 0.3, the friction generated by the film as a packaging bag is too great, resulting in scratches and heat from friction, which can deteriorate the freshness of the fruit and vegetable. This deterioration in freshness is particularly likely to occur with soft-surfaced fruit and leafy vegetables. By setting the coefficient μ' to 0.3 or less, these problems can be prevented. Furthermore, a small dynamic friction coefficient μ' reduces the adhesion of the leaves of leafy vegetables, such as spinach, to the packaging bag, making it easier to maintain them away from the film. This reduces the likelihood of clogging the micropores on the film surface, reducing the reduction in the gas exchange capacity of the packaging bag and inhibiting the respiration of the fruit and vegetable itself, thereby helping to maintain the freshness of the fruit and vegetable. On the other hand, if the dynamic friction coefficient μ' is less than 0.15, the friction becomes too small, and the roll cannot maintain its shape during film production and shifts diagonally, resulting in a so-called "bamboo shoot" shape, which causes problems with production suitability.

[0017] The surface to be arranged as the inner surface is the surface that is arranged on the inside during bag production and that comes into direct contact with the fruit and vegetables when actually used to package the fruit and vegetables. When the film for fruit and vegetable freshness-keeping bags is viewed alone, at least one of the surfaces must satisfy the above-mentioned condition for the coefficient of dynamic friction μ'.

[0018] The dynamic friction coefficient μ' is the dynamic friction coefficient in linear contact in an environment of 40°C. The method for measuring the dynamic friction coefficient in accordance with JIS K7125 is to measure surface contact in an environment of 23°C and 50% RH, but the film for fruit and vegetable freshness-keeping bags according to this invention is intended to fully demonstrate its freshness-keeping effect in the summer, when the freshness of fruit and vegetable is particularly susceptible to deterioration. Furthermore, the contact between the film for fruit and vegetable freshness-keeping bags and the fruit and vegetable packaged therein tends to be point contact or line contact rather than surface contact.

[0019] Therefore, the dynamic friction coefficient μ' of the film for fruit and vegetable freshness-keeping bags according to the present invention is 2 mm when the contact area is 10 mm long and 2 mm when the contact area is 40°C, which is the temperature assumed to be in summer. 2 This is defined as the coefficient of dynamic friction when a load of 100g is applied to a line-like contact (linear contact).

[0020] In order to achieve the above-mentioned dynamic friction coefficient μ', the film for fruit and vegetable freshness-keeping bags according to the present invention preferably has an agent that reduces the dynamic friction coefficient exposed to it. One known method for reducing friction using only a plastic film is embossing, which narrows the contact area between the packaging bag and the contents. However, embossing a film creates distinct irregularities on the film surface, impairing transparency and increasing the risk of reducing the visibility of the state of the fruit and vegetable. In contrast, if only a trace amount of the agent is exposed to the surface, it is possible to reduce the dynamic friction coefficient μ' while minimizing the loss of transparency. "Exposed" refers to a state in which the agent is visible and adhered to the surface, covering at least a portion of it. The method for exposing the agent is not particularly limited, and examples include spraying or applying the agent to adhere or coat the surface, or allowing the agent contained in the plastic film itself to ooze out.

[0021] Suitable agents tend to be those used as emulsifiers, penetrating agents, wetting agents, dispersants, etc. Of course, they must also have the effect of reducing the kinetic friction coefficient μ' of the plastic film. Specific examples include glycerin fatty acid esters (e.g., "SY Glystar PO-3S" manufactured by Sakamoto Pharmaceutical Co., Ltd.) and sucrose fatty acid esters (e.g., "Ryoto Sugar Ester S-970" manufactured by Mitsubishi Chemical Corporation) used as emulsifiers and penetrating / wetting agents, nonionic acetylene glycols (e.g., "Surfynol 465" manufactured by Nissin Chemical Industry Co., Ltd.) used as wetting agents and dispersants, silicone emulsions (e.g., "Dappo H-205N" manufactured by San Nopco Co., Ltd.) used as antifoaming agents and lubricants, and ammonium polycarboxylates (e.g., "Nopco Santo RFA" manufactured by San Nopco Co., Ltd.) used as dispersants. On the other hand, agents used as thickeners and inorganic pigment-based dispersants are not suitable because they increase the kinetic friction coefficient μ' of the surface. Examples of unsuitable agents include modified sodium polyacrylates used as leveling agents or thickeners (such as "SN Thickener 618" manufactured by San Nopco Ltd.), urethane-modified polyethers (such as "SN Thickener 621N" manufactured by San Nopco Ltd.), and quaternary cationic polymers used as inorganic pigment dispersants (such as "Dispersant 4215" manufactured by San Nopco Ltd.).

[0022] The amount of the drug that appears on the surface that is disposed as the inner surface is 5.0 × 10 -3 g / m 2 More than 0.5g / m 2 Although it depends on the type of the drug, it is preferably 5.0 × 10 -3 g / m 2 If it is less than 0.5g / m, the effect of reducing the dynamic friction coefficient μ' is likely to be insufficient. 2 If the haze value exceeds this value, the haze value will be too high, causing problems with the visibility of the packaged fruits and vegetables, and the influence of a decrease in the heat seal strength will become significant.

[0023] The film for fruit and vegetable freshness-keeping bags according to the present invention preferably has a haze value of 1% or more and 10% or less. As the amount of the agent released increases, the distribution becomes non-uniform, and the haze value is likely to increase. If the haze value exceeds 10%, it becomes difficult to distinguish the state of the packaged fruit and vegetable, resulting in a poor appearance, which is undesirable. On the other hand, a lower haze value is preferable, but it is difficult to achieve a haze value of less than 1% with a film that releases the agent.

[0024] The film for fruit and vegetable freshness-keeping bags according to the present invention uses the above-mentioned packaging bag film having an MD width of 15 mm, and is stacked so that the inner surfaces are in contact with each other, and is subjected to a temperature of 150°C for 1 second at a pressure of 2 kgf / cm. 2 When heat-sealed under conditions conforming to JIS Z 0238, the seal strength is preferably 2.0 N / 15 mm or more. Here, MD width refers to the length in the MD (Machine Direction), i.e., the flow direction, during film production. If the seal strength is less than this during bag production, the strength as a packaging bag is likely to be insufficient. However, there is no particular problem with a high seal strength, and there is no particular upper limit.

[0025] The thickness of the film for fruit and vegetable freshness-keeping bags according to the present invention is preferably 15 μm or more. If it is less than 15 μm, it is too thin and the film may tear easily during production, which can cause strength problems. On the other hand, the thickness is preferably 60 μm or less. If it exceeds 60 μm, it may be too thick and difficult to handle as a fruit and vegetable packaging bag. [Example]

[0026] Next, the present invention will be described in more detail with reference to examples in which the present invention is implemented. First, the measurement method used in this example will be described.

[0027] <Dynamic friction coefficient μ' between films> Using the Kyowa Interface Science Co., Ltd. automatic friction and wear analyzer "TSf-502," under an environment of 40°C, which simulates the summer transportation environment, a line contact jig (Kyowa Interface Science Co., Ltd.: Catalog No. 9209 Line Contact) was used to bring the surfaces that would serve as the inner surfaces of the film into line contact (contact area 2 mm) with a length of 10 mm. 2 ) and the dynamic friction coefficient μ' was measured when a load of 100 g was applied.

[0028] <Vibration test> Vibration tests were conducted in accordance with JIS Z 0232 "Packaged cargo - Vibration test method" to check for changes in the appearance of each fruit and vegetable. The specific test conditions were random vibration tests, vibration classification = Level 3, acceleration effective value: 5.8 m / s 2 The vibration frequency range was 3 to 200 Hz, and the vibration time was 15 minutes. The results were visually inspected and classified as follows: ○: Good condition, △: Slight damage, ×: Damaged

[0029] The inner dimensions of the cardboard boxes used were 320mm x 220mm x 190mm. The packaging specifications for each fruit and vegetable were as follows: Spinach test: 200g of spinach was placed in each sample bag measuring 395mm x 210mm, and packed in a cardboard box in two rows of four bags. Broccoli test: Each sample was made into a 320mm x 240mm bag (with six 0.4mm x 0.3mm through-holes) and one broccoli head was placed in each bag. Three bags were packed in two rows in a cardboard box. Test with bell peppers: 150g of bell peppers were placed in 150mm x 200mm bags made for each sample, and packed in a cardboard box in two rows of 4 bags.

[0030] <Freshness preservation effect test> After the vibration test, the fruits and vegetables were stored in a fluctuating environment of 20 to 40°C for 3 days, and then the quality of each fruit and vegetable (change in appearance, presence or absence of an unpleasant odor when opened) was visually evaluated as follows. ○: Good condition, △: Slight discoloration, damage, or strange odor, ×: Discoloration, damage, or strange odor

[0031] <Haze value measurement> Measurement was carried out using a haze meter in accordance with JIS K 7136 "Determination of haze for plastics - transparent materials."

[0032] <Seal strength measurement> Films with an MD width of 15 mm are stacked so that the inner surfaces that will be used as the inner surfaces when making bags are in contact with each other, and then heated to 150°C for 1 second at a pressure of 2 kg / cm. 2 Test pieces were prepared and the seal strength was measured in accordance with JIS Z 0238. Test results of 2.0 N / 15 mm or more were evaluated as "Good", and those of less than 2.0 N / 15 mm were evaluated as "Poor".

[0033] <Sample preparation method and results> (Examples 1 to 3) The substrate was an OPP film (thickness: 20 μm, "FOR" manufactured by Futamura Chemical Co., Ltd.), and the mass before coating was measured. The coating agent was a glycerin fatty acid ester ("SY Glystar PO-3S" manufactured by Sakamoto Pharmaceutical Co., Ltd.), which was adjusted to a predetermined concentration with water. The coating agent was then applied to one side of the film using a bar coater and dried to obtain a sample film. This coated surface became the inner surface of the packaging bag, and the amount of agent exposed on the coated surface was calculated from the difference in mass between the film immediately after coating and the film before coating, and the concentration of the coating solution.

[0034] Example 4 A film was obtained in the same manner as in Example 1, except that the coating agent in Example 1 was changed to a sucrose fatty acid ester (Ryoto Sugar Ester S-970, manufactured by Mitsubishi Chemical Corporation).

[0035] Example 5 A film was obtained in the same manner as in Example 1, except that the coating agent in Example 1 was changed to nonionic acetylene glycol ("Surfynol 465" manufactured by Nisshin Chemical Industry Co., Ltd.).

[0036] Example 6 A film was obtained in the same manner as in Example 1, except that the coating agent in Example 1 was changed to a silicone emulsion (Dappo H-205N, manufactured by San Nopco Ltd.).

[0037] Example 7 A film was obtained in the same manner as in Example 1, except that the coating agent in Example 1 was changed to an ammonium polycarboxylate salt ("Nopco Santo RFA" manufactured by San Nopco Ltd.).

[0038] Example 8 The base material was a polypropylene resin (Japan Polypropylene Corporation, "FL203D") mixed with 2% by weight of glycerin fatty acid ester (Sakamoto Pharmaceutical Industry Co., Ltd., "SY Glystar PO-3S"), and the molten mixture was formed into a film using a T-die film molding machine to obtain a 20 μm thick OPP film. The glycerin fatty acid ester was contained in the resin as a chemical agent and was exposed by seeping onto the surface. The film was cut into 10 cm squares, and the mass of 10 pieces was measured. The exposed chemical agent on one surface of the film (the surface to be used as the inner surface) was wiped off with isopropyl alcohol, after which the mass was measured. The amount of exposed chemical agent was calculated from the mass difference.

[0039] Example 9 In Example 1, the substrate film was changed to a 50 μm thick film laminated with OPP and LLDPE (OPP: "U-1" manufactured by Mitsui Chemicals Tohcello Co., Ltd., LLDPE: "MCS" manufactured by Mitsui Chemicals Tohcello Co., Ltd.), and otherwise a film was obtained using the same procedure as in Example 1.

[0040] (Example and Summary) In all Examples, no damage to the appearance of any fruit or vegetable was observed, confirming that the film exhibited a freshness-preserving effect. Furthermore, the haze values ​​for all were within the acceptable range, meaning that the contents of the fruit or vegetable could be easily inspected. Furthermore, the film seal strength in all cases was suitable for use as a bag.

[0041] [Table 1]

[0042] (Comparative Example 1) The 20 μm OPP film (Futamura Chemical Co., Ltd.'s "FOR") used as the substrate in Examples 1 to 7 was used as is without coating with any chemicals. The dynamic friction coefficient μ' was 0.45, and damage was observed in all fruits and vegetables, and the freshness-preserving effect was not fully exhibited.

[0043] (Comparative Example 2) A general-purpose anti-fog OPP 20μm film ("AF642" manufactured by Futamura Chemical Co., Ltd.) was used as is without any coating of chemicals. The coefficient of dynamic friction μ' was 0.37, and damage was observed in all fruits and vegetables, and the freshness-preserving effect was not fully achieved.

[0044] (Comparative Examples 3 and 4) A film was obtained in the same manner as in Example 1, except that the coating amount of the agent in Example 1 was changed so that the amount of agent exposed on the surface to be disposed as the inner surface was calculated to be the value shown in Table 2. In Comparative Example 3, the coating amount was smaller than in Example 1, thereby suppressing the reduction in the dynamic friction coefficient μ', and in Comparative Example 4, the coating amount was larger than in Example 1. In Comparative Example 3, the dynamic friction coefficient μ' could not be sufficiently reduced, so damage was observed in all fruits and vegetables, and the freshness-preserving effect was not fully exhibited. In Comparative Example 4, the dynamic friction coefficient μ' was reduced, so the freshness-preserving effect was fully exhibited, but the seal strength was insufficient due to the excessive amount of agent, causing problems as a packaging bag.

[0045] (Comparative Example 5) A film was obtained in the same manner as in Example 6, except that the coating amount of the drug was increased so that the amount of drug exposed on the surface to be disposed as the inner surface was calculated to be the value shown in Table 2. Although the reduction in the dynamic friction coefficient μ' enabled a sufficient freshness-preserving effect, the amount of drug exposed was too high, which significantly worsened the haze value, making it difficult to check the contents, and the seal strength was also insufficient.

[0046] (Comparative Example 6) A film was obtained in the same manner as in Example 7, except that the coating amount of the drug was increased so that the amount of drug exposed on the surface to be disposed as the inner surface was calculated to be the value shown in Table 2. Although the reduction in the dynamic friction coefficient μ' enabled a sufficient freshness-preserving effect, the amount of drug exposed was too high, which worsened the haze value, making it difficult to check the contents, and the seal strength was also insufficient.

[0047] (Comparative Example 7) In Example 1, the coating agent was changed to modified sodium polyacrylate ("SN Thickener 618" manufactured by San Nopco Ltd.), and otherwise a film was obtained using the same procedure as in Example 1. Compared to Comparative Example 1, there was almost no effect in reducing the dynamic friction coefficient μ', and compared to Comparative Example 1, damage to the appearance of all fruits and vegetables increased, and the freshness-preserving effect was not fully exerted.

[0048] (Comparative Example 8) In Example 1, the coating agent was changed to a urethane-modified polyether ("SN Thickener 621N" manufactured by San Nopco Ltd.), and otherwise a film was obtained in the same manner as in Example 1. Due to the effect of the dynamic friction coefficient μ' being higher than in Comparative Example 1, damage to the appearance of all fruits and vegetables was observed, and the freshness-preserving effect was not fully exerted.

[0049] (Comparative Example 9) In Example 1, the coating agent was changed to a quaternary cationic polymer (Dispersant 4215, manufactured by San Nopco Ltd.), and otherwise a film was obtained using the same procedure as in Example 1. Due to the effect of the dynamic friction coefficient μ' being higher than in Comparative Example 1, damage to the appearance of all fruits and vegetables was clearly visible, and the freshness-preserving effect was not fully exerted.

[0050] (Comparative Example 10) A 20μm thick OPP film (Futamura Chemical Co., Ltd. "FOR") was used as the base material, and a grid-like undulation was created by embossing, with 2mm squares and a height difference of 100μm. No chemicals were applied. Although the freshness-preserving effect was achieved, the embossing process worsened the haze value, making it difficult to see the contents.

[0051] (Comparative Example 11) The 50 μm thick film made of laminated OPP and LLDPE, which was used as the base material in Example 9, was used as is without being coated with any chemicals. Damage was observed in all fruits and vegetables, and the freshness-preserving effect was not fully exerted.

[0052] [Table 2]

[0053] <Winding test> An OPP film (thickness: 20 μm, "FOR" manufactured by Futamura Chemical Co., Ltd.) was used as a substrate. Using the same chemicals as those used in Example 5 and Comparative Example 4, the film was coated with the chemicals using a multi-coater "TM-MC" manufactured by Hirano Tecseed Co., Ltd., so that the chemical exposure amount was similar to that of Example 5 and Comparative Example 4. The coated film was then wound up and examined for the occurrence of winding slippage. The conditions were: unwinding force 30 N / 300 mm, winding tension 35 N / 300 mm, speed 40 m / min, original roll width 300 mm, and processing length 1000 m. As a result, winding slippage did not occur with the film corresponding to Example 5, which had a dynamic friction coefficient μ' of 0.15, but winding slippage did occur with the film corresponding to Comparative Example 4, which had a dynamic friction coefficient μ' of 0.12. From these results, it is thought that the film of Comparative Example 4 would cause misalignment of the film and become "bamboo shoot-like", which would cause production problems, when used in a production device that handles the film in roll form, but the film of Example 5 can be produced smoothly without misalignment of the film, even when used in a production device that handles the film in roll form.

Claims

1. A heat-sealable film for packaging bags, the film being made of a single-layer or multi-layer polypropylene plastic film as a base material, wherein the coefficient of dynamic friction μ' between the inner surfaces of the film is 0.15 or more and 0.3 or less when a load of 100 g is applied to the film over a 10 mm length and a 2 mm 2 contact area in an environment of 40°C, the amount of an agent that reduces the coefficient of dynamic friction and is selected from glycerin fatty acid ester, sucrose fatty acid ester, acetylene glycol, silicone emulsion, and polycarboxylic acid ammonium salt exposed on the surface to be disposed as the inner surface is 5.0×10 −3 g / m 2 or more and 0.5 g / m 2 or less; A film for a freshness-keeping bag for fruits and vegetables having a thickness of 15 μm or more and 60 μm or less.

2. A film for use in bags for preserving the freshness of fruits and vegetables as described in claim 1, wherein the amount of the agent exposed is 0.04 g / m 2 or more.

3. The haze value is 1% or more and 10% or less, and The packaging bag film having an MD width of 15 mm was stacked so that the inner surfaces were in contact with each other, and the film was subjected to a pressure of 2 kgf / cm at 150°C for 1 second. ２ Heat-sealed by JIS The seal strength measured under conditions in accordance with Z 0238 is 2.0 N / 15 mm or more. The film for use in a bag for preserving the freshness of fruits and vegetables according to claim 1 or 2.

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