KR20200115198A - Packaging sheet - Google Patents

Abstract

The present invention relates to a packaging sheet capable of making a surface of a protection target sufficiently clean after washing with water. A polyethylene-based resin foam sheet in which a polyoxyethylene-based nonionic surfactant having an HLB value of 15 or higher is used in combination with an anionic surfactant is used.

Description

Packing sheet{PACKAGING SHEET}

The present invention relates to a sheet for packaging, and more particularly, to a sheet for packaging provided with a polyethylene-based resin foam sheet.

The polyethylene-based resin foam sheet is flexible and has excellent buffering properties compared to a polystyrene-based resin foam sheet or a polyester-based resin foam sheet.

For this reason, a polyethylene-based resin foam sheet is widely used as a packaging sheet for packaging articles such as electronic parts, home appliances, and glass plates.

As this type of packaging sheet, a sheet in which a polyethylene-based resin foam sheet is exposed on a surface in contact with the packaged product is known. A sheet of a polyethylene-based resin foam sheet alone or a mark sheet on one side of a polyethylene-based resin foam sheet, etc. This laminated one and the like are known.

The packaging sheet is also used as a laminate to be inserted between these components when storing members such as a glass plate, a semiconductor substrate, and a metal plate, which are the substrates of a flat display panel.

The packaging sheet used for this paper or the like is required to have antistatic properties for preventing foreign substances from adhering to articles such as a glass plate or a metal plate.

For this reason, efforts have been widely made to exhibit antistatic properties for polyethylene-based resin foam sheets.

As a method of exerting antistatic properties to the polyethylene-based resin foam sheet, a polymer-type antistatic agent called a polymeric antistatic agent or a surfactant called a low molecular weight antistatic agent is contained in the material for forming the polyethylene-based resin foam sheet. How to do is known.

The surfactant usually bleeds out to the surface of the polyethylene-based resin foam sheet to exhibit antistatic properties.

For this reason, when such a polyethylene-based resin foam sheet is used as a laminate of a glass plate or the like, the bleed-out surfactant adheres to the surface of the glass plate.

The polymeric antistatic agent is used for the purpose of preventing the surfactant from adhering to the glass plate by reducing the amount of surfactant added to the polyethylene-based resin foam sheet.

On the other hand, as described in Patent Literature 1 below, even if the surfactant adheres to an article such as a glass plate, there are cases where it can be easily removed by washing the article with water, and rather, the surfactant is effective in cleaning the surface of the article after washing with water. Sometimes it works.

Japanese Unexamined Patent Publication No. 2010-42556

The use of a surfactant becomes a factor in expressing tackiness in the polyethylene-based resin foam sheet.

When a polyethylene-based resin foam sheet having tackiness on its surface is used as a packaging sheet, there may be a situation in which foreign matters tend to adhere to the surface before packaging of the article.

For this reason, when a polyethylene-based resin foam sheet having tackiness is used for a packaging sheet, there is a possibility that foreign matter adheres to the packaged article.

From the above point of view, it has become difficult to exhibit sufficiently good cleanliness on the surface of the article after washing with water.

However, no particularly effective method for solving this problem is known.

Accordingly, it is an object of the present invention to provide a packaging sheet capable of sufficiently cleansing the surface of an article to be protected after washing with water.

As a result of intensive examination by the present inventors, it was found that a packaging sheet capable of satisfying the above requirements can be obtained by using in combination with a specific surfactant to prevent antistatic in a polyethylene-based resin foam sheet, thereby completing the present invention.

The present invention for solving the above problems,

As a packaging sheet provided with a polyethylene-based resin foam sheet composed of a polyethylene-based resin composition,

The polyethylene-based resin foam sheet is provided so as to be exposed on at least one surface of the packaging sheet,

The polyethylene-based resin foam sheet is provided with an anionic surfactant and a nonionic surfactant,

The anionic surfactant is provided in a state coated on the one surface or mixed with the polyethylene-based resin foam sheet, and

The nonionic surfactant is mixed and provided in the polyethylene-based resin foam sheet,

A packaging sheet is provided in which the nonionic surfactant is a polyoxyethylene surfactant having an HLB value of 15 or higher.

In the present invention, since the anionic surfactant and the specific nonionic surfactant are provided in the polyethylene resin foam sheet, a packaging sheet capable of sufficiently cleansing the surface of the packaged article after washing with water can be provided.

1 is a schematic diagram showing an aspect of use of the packaging sheet of the present invention.
2 is a schematic cross-sectional view of a packaging sheet according to an embodiment of the present invention.

The packaging sheet of the present invention will be described.

In the following, the case where the sheet for packaging is composed of a polyethylene-based resin foam sheet alone is illustrated.

In addition, below, the polyethylene-type resin foam sheet in the state in which coating was applied to the extrusion foam sheet is illustrated.

More specifically, the packaging sheet of this embodiment is a polyethylene-based resin foam sheet in which an anionic surfactant is coated on both sides of an extruded foam sheet obtained by extrusion foaming a polyethylene-based resin composition containing a polyethylene-based resin to form a coating film. to be.

As shown in FIG. 1, the packaging sheet 1 of this embodiment is used, for example as a lamination of a glass plate.

The packaging sheet 1 of the present embodiment is used by being inserted between adjacent glass plates 2 when forming the laminate 100 by stacking a plurality of glass plates 2 in the vertical direction.

The packaging sheet 1 in this embodiment is composed of a polyethylene-based resin foam sheet, and the polyethylene-based resin foam sheet is exposed to the surface on both sides.

As shown in FIG. 2, the packaging sheet 1 of the present embodiment includes an extrusion foam sheet 10 serving as a base material and a coating film 11 formed on the extrusion foam sheet, as shown in FIG. 2. , 12).

The glass plate 2 in this embodiment is a glass plate for flat display panels such as a plasma display panel or a liquid crystal display panel.

The packaging sheet 1 of the present embodiment includes a first coating film 11 laminated on the first surface of the extruded foam sheet 10, and a second coating film laminated on a second surface opposite to the first surface. (12) is provided.

Therefore, the polyethylene-based resin foam sheet constituting the packaging sheet 1 of the present embodiment has a three-layer structure of the first coating film 11 / the extrusion foam sheet 10 / the second coating film 12 microscopically. Are doing.

Examples of the polyethylene resin that can be contained in the polyethylene resin composition constituting the polyethylene resin foam sheet of the present embodiment include high density polyethylene (HDPE), medium density polyethylene (MDPE), and low density polyethylene. .

Examples of the low-density polyethylene resin include a straight-chain low-density polyethylene resin (LLDPE) polymerized by a medium and low-pressure method, or a low-density polyethylene resin (LDPE) in which long-chain branches are formed in a molecular structure by a high-pressure method.

In the polyethylene-based resin composition constituting the polyethylene-based resin foam sheet, it is not necessary to contain one type of polyethylene-based resin alone, and two or more types may be included.

As the polyethylene resin to be contained in the polyethylene resin composition, a low density polyethylene resin is preferable.

As the low-density polyethylene resin, a low-density polyethylene resin (LDPE) having a melt mass flow rate (hereinafter, referred to as "MFR") of 2 to 6 g/10 min, and a resin density of 925 kg/m 3 or more and 935 kg/m 3 or less is used. It is desirable to do.

In the present specification, the melt mass flow rate (MFR) is JIS K 7210:1999 "Test method of melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastics" unless otherwise specified. It is measured by the method described in Method B (however, the test temperature is 190°C and the load is 21.18N).

It is preferable that the polyethylene-based resin contained in the extruded foam sheet 10 of the present embodiment has the same density as described above. When the resin density is less than 925 kg/m 3, the daily production of the foaming agent from the foam sheet after extrusion is quick, and the resin This is because the rigidity of itself is small, and there is a fear that the shrinkage cannot be suppressed. In addition, it is preferable to have the above-described density because, when the resin density is set to a value exceeding 935 kg/m 3, the rigidity of the resin itself is too large, and the packaging sheet may not exhibit good cushioning properties.

The polyethylene-based resin foam sheet of the present embodiment is provided with an anionic surfactant and a nonionic surfactant.

Among these surfactants, a nonionic surfactant is contained in the polyethylene resin composition constituting the extruded foam sheet 10.

That is, the nonionic surfactant is provided in a state mixed with the polyethylene-based resin foam sheet.

The anionic surfactant is provided in the polyethylene-based resin foam sheet in a state included in the first coating film 11 and the second coating film 12, as described above at a later stage.

That is, the polyethylene-based resin foam sheet contains a nonionic surfactant therein and an anionic surfactant on both surfaces thereof.

In addition, in the polyethylene-based resin composition constituting the polyethylene-based resin foam sheet, in addition to the resin composition constituting the extruded foam sheet 10, an anionic surfactant constituting the first coating film 11 and the second coating film 12 Is included.

The anionic surfactant may not only be contained in the first coating film 11 or the second coating film 12, but may be contained in the extruded foam sheet 10 together with a nonionic surfactant.

That is, the anionic surfactant may be provided in a coated state on the surface of the polyethylene-based resin foam sheet, or may be provided in a state mixed with the polyethylene-based resin foam sheet.

When incorporated into the polyethylene-based resin foam sheet and provided, the anionic surfactant is contained in the extruded foam sheet 10 in the same manner as the nonionic surfactant.

The nonionic surfactant in this embodiment is a polyoxyethylene surfactant.

Examples of the polyoxyethylene-based surfactant include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene glycerin fatty acid ester.

The polyoxyethylene surfactant may be polyoxyethylene fatty acid amide, polyoxyethylene hydrogenated castor oil, or the like.

The polyoxyethylene-based surfactant is preferably any one of polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene glycerin fatty acid ester, and is polyoxyethylene alkyl ether. It is more preferable.

The polyoxyethylene alkyl ether is, for example, a compound in which a hydrophilic portion having a polyoxyethylene number of 2 to 60 and a lipophilic portion of an alkyl having 8 to 24 carbon atoms are ether-bonded via a terminal oxygen atom of the hydrophilic portion, or a mixture thereof Can be mentioned.

Specifically, as the polyoxyethylene alkyl ether, for example, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether B, a mixture of two or more of these may be used.

The polyoxyethylene alkyl ether is provided in a state mixed with the polyethylene-based resin foam sheet, thereby exhibiting the effect of suppressing the occurrence of deposits on the glass plate that cannot be easily removed by washing with water such as grease or metal soap.

In order to exhibit these effects more remarkably, it is preferable that the polyoxyethylene alkyl ether has an HLB value within a predetermined range.

As for the said polyoxyethylene alkyl ether in this embodiment, it is preferable that HLB is 15 or more, it is more preferable that HLB is 16 or more, and it is still more preferable that HLB is 17 or more.

The "HLB" value in the present embodiment means a value obtained by the Griffin method, and means a value obtained by the following formula (A).

HLB=20×Total of food in the hydrophilic part/molecular weight… (A)

Examples of the polyoxyethylene fatty acid ester include polyoxyethylene lauric acid ester, polyoxyethylene myristic acid ester, polyoxyethylene palmitic acid ester, polyoxyethylene stearic acid ester, and polyoxyethylene oleic acid ester. Can be lifted.

Examples of the polyoxyethylene sorbitan fatty acid ester include polyoxyethylene sorbitan lauric acid ester, polyoxyethylene sorbitan myristic acid ester, polyoxyethylene sorbitan palmitic acid ester, and polyoxyethylene sorbitan stear. Acid ester, polyoxyethylene sorbitanoleic acid ester, etc. are mentioned.

As the polyoxyethylene glycerin fatty acid ester, for example, polyoxyethylene glycerin monolauric acid ester, polyoxyethylene glycerin monomyritic acid ester, polyoxyethylene glycerin monopalmitic acid ester, polyoxyethylene glycerin monostearic acid Ester, polyoxyethylene glycerin monooleic acid ester, etc. are mentioned.

The content of the nonionic surfactant in the polyethylene resin foam sheet is usually 0.05% by mass or more and 2.0% by mass or less.

The content of the nonionic surfactant in the polyethylene resin composition is usually 0.05 parts by mass or more when the content of the polyethylene resin is 100 parts by mass.

The content of the nonionic surfactant is preferably 0.1 parts by mass or more, and more preferably 0.2 parts by mass or more.

The content of the nonionic surfactant is preferably 2.0 parts by mass or less, and more preferably 1.0 parts by mass or less.

It is not necessary to use one type of the nonionic surfactant alone, and two or more types may be mixed and contained in the polyethylene resin composition.

In the case of containing two or more types of nonionic surfactants, at least one type of nonionic surfactant may be used as a polyoxyethylene surfactant whose HLB has the same value as above, and all of the HLB values have the same values as above. It is preferably composed of a polyoxyethylene-based surfactant showing.

In the case of containing two or more types of nonionic surfactants, the proportion of the polyoxyethylene surfactants in which HLB exhibits the above values in all nonionic surfactants is preferably 50% by mass or more, and 70 mass% It is more preferable that it is more than %, and it is still more preferable that it is 90 mass% or more.

In the case of using a plurality of nonionic surfactants, it is preferable to contain them in the polyethylene resin composition so that the total value of the content falls within the numerical range.

In addition, when the total amount of the nonionic surfactant to be contained is 100% by mass, it is preferably adjusted so that 50% by mass or more is the polyoxyethylene alkyl ether described above.

The proportion of the polyoxyethylene alkyl ether in the nonionic surfactant is more preferably 60% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, and 90% by mass or more. Especially preferred.

Examples of the anionic surfactant include alkyl sulfonate, dialkyl sulfosuccinate, alpha olefin sulfonate, linear alkylbenzene sulfonate, naphthalene sulfonate-formaldehyde condensate, alkyl naphthalene sulfonate, N-methyl- Sulfonate-based surfactants such as N-acyltaurine salts; Carboxylate-based surfactants such as aliphatic monocarboxylate, polyoxyethylene alkyl ether carboxylate, N-acyl sarcosine, and N-acyl glutamate; Sulfuric acid ester salt-based surfactants such as alkyl sulfuric acid ester salts, polyoxyethylene alkyl ether sulfates, and oil sulfuric acid ester salts; Phosphoric acid ester salt-based surfactants such as alkyl phosphate, polyoxyethylene alkyl ether phosphate, and polyoxyethylene alkyl phenyl ether phosphate can be used.

On the other hand, it is not necessary to use one type of the anionic surfactant alone, and may be used in combination of two or more.

It is preferable that the content of the anionic surfactant in the polyethylene-based resin foam sheet is adjusted to be larger than that of the nonionic surfactant.

The content of the anionic surfactant in the polyethylene resin foam sheet is usually 0.05% by mass or more and 5.0% by mass or less.

Accordingly, the content of the anionic surfactant in the polyethylene resin composition for producing the extruded foam sheet varies depending on the content of the anionic surfactant in the coating film, but the content of the polyethylene resin is 100 parts by mass. In this case, it is usually 0.05 parts by mass or more and 5.0 parts by mass or less.

The polyethylene resin composition constituting the extruded foam sheet 10 of the present embodiment may contain a polymeric antistatic agent as an optional component.

Examples of the polymeric antistatic agent include ionomers such as polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, ethylene-methacrylic acid copolymer, polyethylene glycol methacrylate copolymer, etc. And the quaternary ammonium salt of JP 2001-278985, a copolymer of an olefinic block and a hydrophilic block, and the like.

The content of the polymeric antistatic agent in the polyethylene resin composition is 1% by mass or less.

On the other hand, in the packaging sheet according to the present embodiment, the surface cleanliness of the article to be packaged after washing with water tends to improve according to the amount of the polymeric antistatic agent.

Accordingly, the content is more preferably 0.5% by mass or less, and particularly preferably substantially 0% by mass (less than the detection limit).

That is, it is preferable that the polyethylene-based resin foam sheet does not contain a polymer-type antistatic agent at all, and even if it contains, the content is 1% by mass or less.

Since the extruded foam sheet 10 of this embodiment is manufactured by the extrusion foaming method, in addition to the components described so far, components necessary for foaming may be additionally contained.

As a component for this foaming, a foaming agent and a foam control agent are mentioned.

Examples of the blowing agent include hydrocarbons such as isobutane, normal butane, propane, pentane, hexane, cyclobutane, and cyclopentane, and inorganic gases such as carbon dioxide and nitrogen.

Among them, mixed butane, which is a mixture of isobutane and normal butane, is preferable as the blowing agent.

When mixed butane is used in this way, the rapid daily acidity of the foaming agent in the extrusion step is suppressed by isobutane. On the other hand, since normal butane having excellent compatibility with a polyethylene-based resin suppresses an increase in the continuous cell rate, it is possible to obtain an extruded foam sheet 10 having less shrinkage and excellent cushioning properties with less continuous cell rate.

The amount of the foaming agent used during extrusion foaming varies depending on the degree of foaming required, but is usually 5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the polyethylene-based resin.

Usually, the addition ratio of the foaming agent is in such a range because if the foaming agent is less than 5 parts by mass, it is difficult to obtain sufficient foaming, and if it exceeds 25 parts by mass, the foam film is torn, and a good polyethylene resin foam sheet may not be obtained. .

Examples of the foam control agent for adjusting the foam formed by the foaming agent include inorganic powders such as talc and silica. A mixture of polyhydric carboxylic acid and sodium carbonate or sodium bicarbonate (sodium bicarbonate) used as a decomposition foaming agent, azodicarboxylic acid amide, or the like may be used as the foam control agent.

These may be used independently or may use multiple things together.

It is preferable that the addition amount of this foam modifier is 0.5 parts by mass or less per 100 parts by mass of the polyethylene-based resin.

In addition to the above components, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant, and a colorant may be contained in the extruded foam sheet 10 of the present embodiment as needed.

In addition to the polyethylene-based resin, nonionic surfactant, and anionic surfactant, the proportion of components contained in the polyethylene-based resin foam sheet is preferably 10% by mass or less, more preferably 5% by mass or less, and furthermore 2% by mass or less. desirable.

That is, the total ratio of the polyethylene-based resin, nonionic surfactant, and anionic surfactant in the polyethylene-based resin foam sheet is preferably 90% by mass or more, more preferably 95% by mass or more, and 98% by mass or more. More preferable.

The density (apparent density) of the extruded foam sheet 10 constituted by the above polyethylene resin composition is not particularly limited, and may be such that it exhibits cushioning properties generally required for lamination of glass plates, etc. It is usually less than 70 kg/㎥, preferably 10 kg/㎥ or more and 60 kg/㎥ or less.

The reason why such a density can be selected is that when the density is 70 kg/m 3 or more, the flexibility of the extruded foam sheet 10 may be insufficient and the buffering property may be low. If the density is too small, the extruded foam sheet 10 This is because, as a result of not having sufficient strength, there is a possibility that the buffering property may be low.

In addition, when the thickness of the foam film becomes too thin, the shrinkage increases, and as a result, when the extruded foam sheet 10 is manufactured, it becomes difficult to wind it up with one roll.

Therefore, the density of the extruded foam sheet 10 is preferably 10 kg/m 3 or higher, and preferably 15 kg/m 3 or higher.

As described above, the packaging sheet of the present embodiment has coating films 11 and 12 containing anionic surfactants on both surfaces of the extruded foam sheet 10.

The first coating film 11 and the second coating film 12 of the extruded foam sheet 10 may or may not have the same type or content of the anionic surfactant they contain.

In the point that the packaging sheet can be used as a laminate of a glass plate regardless of the front and back, it is preferable that the type and content of the anionic surfactant of the first coating film 11 are in common with the second coating film 12.

It is preferable that the anionic surfactant contained in the first coating film 11 or the second coating film 12 can be removed by washing with water from the surface of an article to be packaged such as a glass plate over a long period of time.

That is, it is preferable that the anionic surfactant is less likely to cause a reaction due to oxygen, moisture, or ultraviolet rays in the air, and that water solubility is less likely to be lost.

It is preferable that the first coating film 11 and the second coating film 12 contain an anionic surfactant represented by the following formula (1).

Here, in formula (1), "R-" is a monovalent organic group represented by the following formula (2), "n" is an integer of 1 to 150, and "-X" is an anionic functional group.

Here, "m" in Formula (2) is an integer of 1-14.

That is, "R-" in formula (1) is a monovalent group in which one hydrogen atom has been removed from a linear or branched alkane.

Examples of the anionic functional group (-X) include those represented by the following formulas (a1) to (a4).

Here, "M ⁺ " in formulas (a1) to (a4) represents a monovalent cation.

On the other hand, "m" in formula (2) is preferably 6 or more (6 to 14), more preferably 8 or more (8 to 14), and particularly preferably 10 or more (10 to 14). .

It is particularly preferable that "m" is either 12 or 13.

In addition, the anionic functional group (-X) is preferably a sulfate represented by formula (a2).

Further, as the cation (M ⁺ ), metal ions such as lithium ions, potassium ions, and sodium ions, and ammonium ions are preferable.

Among them, the cation (M ⁺ ) is preferably a sodium ion.

It is particularly preferable that the polyoxyethylene alkyl ether type anionic surfactant represented by formula (1) is either sodium polyoxyethylene lauryl ether sulfate or sodium polyoxyethylene tridecyl ether sulfate.

In the first coating film 11 and the second coating film 12, the polyoxyethylene alkyl ether type anionic surfactant represented by the formula (1) may be contained singly or two or more.

The first coating film 11 and the second coating film 12 may contain anionic surfactants other than the polyoxyethylene alkyl ether type anionic surfactant represented by the formula (1), but the first It is preferable that 95 mass% or more of the anionic surfactant contained in the coating film 11 and the said 2nd coating film 12 is a polyoxyethylene alkyl ether type anionic surfactant represented by the said formula (1).

In particular, the ratio of the polyoxyethylene alkyl ether type anionic surfactant represented by the formula (1) to the anionic surfactant contained in the first coating film 11 and the second coating film 12 is 98% by mass or more. desirable.

It is particularly preferable that the first coating film 11 and the second coating film 12 consist of substantially only a polyoxyethylene alkyl ether type anionic surfactant represented by the above formula (1).

The anionic surfactant contained in the coating films 11 and 12 is formed on the surface of the glass plate 2 by contact between the glass plate 2 and the packaging sheet 1, which is a surface-protected object protected by the packaging sheet 1. Then, a hydrophilic protective film is formed on the surface of the glass plate 2.

Further, in the packaging sheet 1 according to the present embodiment, the occurrence of adhesions with low hydrophilicity to the glass plate is suppressed by mixing a polyoxyethylene-based nonionic surfactant in the polyethylene-based resin foam sheet.

Thereby, the glass plate 2 can be in a clean surface state after washing with water.

In addition, the glass plate 2 can be maintained in a state that can become a clean surface condition after washing with water for a long period of time.

Therefore, the surface of the glass plate 2 can be easily cleaned even after long-term storage for 3 months or more in a state in which the packaging sheet 1 of the present embodiment is inserted as a laminate.

In the present embodiment, if the coating film contains an anionic surfactant having an alkyl group having the same chain length as described above, even if the same anionic surfactant has a long chain length of the alkyl group, sufficient hydrophilicity is exhibited in the protective film on the surface of the glass plate (2). This is because the surface of the glass plate 2 is liable to generate a lipophilic deposit, which is less easy to wash and remove than an anionic surfactant.

Moreover, even if it has an alkyl group of the same chain length, if the surfactant is a nonionic surfactant other than an anionic surfactant, it becomes difficult to exhibit sufficient hydrophilicity to the protective film on the surface of the glass plate 2.

In order not to generate a lipophilic deposit on the surface of the glass plate 2, the content of the fatty acid compound is preferably not more than a predetermined in the polyethylene-based resin foam sheet of the present embodiment.

Specifically, the content of the fatty acid compound in the polyethylene resin foam sheet is preferably 10 ppm or less, more preferably 9 ppm or less, still more preferably 8 ppm or less, and particularly preferably 7 ppm or less.

The content of the fatty acid compound in the polyethylene-based resin foam sheet may be 6 ppm or less, or 5 ppm or less.

It is preferable that the content of stearic acid amide is predetermined or less among fatty acid compounds in the polyethylene-based resin foam sheet.

Specifically, the content of stearic acid amide in the polyethylene-based resin foam sheet is preferably 7 ppm or less, more preferably 6 ppm or less, and still more preferably 5 ppm or less.

It is particularly preferable that the content of stearic acid amide in the polyethylene-based resin foam sheet is 4 ppm or less.

The fatty acid compound may be contained in commercially available resin pellets as an external lubricant or an internal lubricant of a polyethylene-based resin.

Therefore, in the case of employing a commercially available product as the polyethylene resin contained in the polyethylene-based resin foam sheet, it is preferable to employ a fatty acid compound having the above content.

That is, the polyethylene-based resin preferably has a fatty acid compound content of 10 ppm or less, more preferably 9 ppm or less, even more preferably 8 ppm or less, and particularly preferably 7 ppm or less.

The content of the fatty acid compound in the polyethylene resin may be 6 ppm or less, or 5 ppm or less.

Further, the content of stearic acid amide in the polyethylene resin is preferably 7 ppm or less, more preferably 6 ppm or less, and still more preferably 5 ppm or less.

It is particularly preferable that the content of stearic acid amide in the polyethylene resin is 4 ppm or less.

In the present embodiment, by the presence of the anionic surfactant or the nonionic surfactant on the surface of the polyethylene resin foam sheet, even if these fatty acid compounds are contained in the polyethylene resin foam sheet, the fatty acid compound is contained in the packaged article. Adhesion is suppressed.

However, in order to more reliably prevent adhesion of the fatty acid compound, the content of the fatty acid compound is preferably set to the same value as described above.

When the anionic surfactant or the nonionic surfactant is mixed in the extruded foam sheet, it is effective to use master pellets containing these surfactants at a higher concentration than the concentration of these surfactants in the extruded foam sheet. Do.

When manufacturing an extruded foam sheet using the anionic surfactant or the master pellet containing the nonionic surfactant, the extrusion foam sheet is usually extruded using a mixed pellet of a polyethylene resin pellet containing no surfactant and a master pellet. Foaming is carried out.

At this time, when the ratio of the master pellets to the total of the master pellets and the polyethylene resin pellets is "X (%)" and the dilution ratio of the master pellets is "Y (times)", "X (%)" Between and "Y (fold)", the following relationship is generally established.

Y=(100／X)

For this reason, when the master pellet is diluted in the polyethylene-based resin pellet not containing the fatty acid compound, the fatty acid compound may be contained in the master pellet in a Y-fold ratio of the above-described content.

This is the same not only when the surfactant is contained in the extruded foam sheet as a master pellet, but also when various additives are contained in the extruded foam sheet as a master pellet.

As described above, the fatty acid compound functions as an external lubricant for suppressing excessive friction between the inner wall surface of the cylinder of the extruder or the flight of the screw, and the resin melt-kneaded in the extruder.

In this embodiment, by using a master pellet containing a surfactant at a high concentration, it can be expected that a part of the surfactant bleeds out from the master pellet in the extruder to act as an external lubricant.

The content of the surfactant (the total content of the anionic surfactant and the nonionic surfactant) in the master pellet is preferably 2.5% by mass or more.

The content of the surfactant in the master pellet is more preferably 3% by mass or more, still more preferably 3.5% by mass or more, and particularly preferably 4% by mass or more.

The content of the surfactant in the master pellet may be 5% by mass or more or 6% by mass or more.

Since it is difficult to contain the surfactant in an excessive proportion in the master pellet, the content of the surfactant is preferably 15% by mass or less, and more preferably 10% by mass or less.

As the fatty acid compound in this embodiment, a fatty acid, a fatty acid metal salt, a fatty acid amide, a fatty acid ester, etc. are mentioned, for example.

Specific examples of fatty acids include saturated fatty acids such as lauric acid, palmitic acid, stearic acid, and behenic acid, unsaturated fatty acids such as oleic acid, erucic acid, linoleic acid, and linolenic acid, and dimer acids in addition to these monocarboxylic acids. Dicarboxylic acids, such as, etc. are mentioned.

Metals constituting the fatty acid metal salt include calcium, magnesium, aluminum, and zinc.

Fatty acid amide is an acid amide derived from fatty acid.

Examples of the fatty acid amide include those derived from aliphatic amines.

As a specific example of fatty acid amide, stearic acid amide, palmitic acid amide, oleic acid amide, erucic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bishydroxystearic acid amide, etc. Can be mentioned.

Specific examples of fatty acid esters include butyl stearate, stearate monoglyceride, oleic acid monoglyceride, behenic acid monoglyceride, linoleic acid monoglyceride, ricinoleic acid monoglyceride, hydroxystearic acid triglyceride, sorbitan fatty acid ester, polyoxyethylene (5) Glycerin monostearate, polyoxyethylene (20) Glycerin monostearate, polyoxyethylene (5) monooleate, pentaerythritol tetrastearate, polyadipic acid pentaerythritol stearate, stearyl stearate, 1, 2-oxystearic acid, hydrogenated castor oil, etc. are mentioned.

A known method can be used as a method for measuring the content of the fatty acid compound in the polyethylene-based resin foam sheet.

As the method, the following methods are mentioned, for example.

About the fatty acid metal salt, it is measured as follows, for example.

A polyethylene-based resin foam sheet is immersed in boiling methanol and extracted, and the precipitate deposited by standing to cool is separated by filtration. When the precipitate is suspended in dilute hydrochloric acid and solvent is extracted with ether, the fatty acid free in the ether phase and the metal are extracted into the aqueous phase, respectively, so the fatty acid is extracted by the method described below, and the metal is ICP (Inductively Coupled Plasma) luminescence analyzer. The metal species can be identified and quantified by, for example.

The determination of the fatty acid, the fatty acid amide, and the fatty acid ester is performed in the same manner as in the method of ``quantification of surfactant'' described later, and a liquid chromatography tandem mass spectrometer (LC-MS/MS) (e.g., manufactured by Termo SCIENTIFIC). ACCELA") can be used.

On the other hand, the calibration curve used for quantification of fatty acid compounds is a standard solution (methanol solution) with a concentration of 1000 ppm of a fatty acid compound (fatty acid, fatty acid amide, fatty acid ester) to be quantified and diluted with methanol to prepare five different standard solutions (5 ppm). , 2ppm, 1ppm, 0.5ppm, 0.2ppm).

In addition, a sample measured by LC-MS/MS is prepared as follows.

Cut a polyethylene-based resin foam sheet into a size of about 2 mm in width and length, and extract about 0.15 g of a sample.

-The extracted sample is precisely weighed, and the extracted sample is put into a pressure-resistant container made of PTFE (polytetrafluoroethylene) together with 10 ml of methanol, and the pressure-resistant container is sealed.

• After heating the sealed pressure-resistant container in an oven at 120°C for 2 hours, take it out of the oven and let it cool naturally in a room at room temperature.

Open the pressure-resistant container cooled to room temperature and filter the extract in the container with filter paper (No.5A).

-The filtrate obtained by the above filtration is used as a measurement sample by LC-MS/MS.

-From the measurement result, the amount of the fatty acid compound in the filtrate is calculated using the calibration curve obtained earlier.

-The content (ppm) of the fatty acid compound in the polyethylene resin foam sheet is determined from the amount of the fatty acid compound contained in the filtrate.

In the present embodiment, it is preferable that the above-described anionic surfactant is not bleed out from the inside of the polyethylene-based resin foam sheet, but is maintained on the surface of the polyethylene-based resin foam sheet in the state of a coating film.

That is, the amount (mass) of the anionic surfactant in the polyethylene-based resin foam sheet is preferably less than the content in the coating film (the total amount of the first coating film and the second coating film).

Specifically, the amount (mass) of the anionic surfactant in the polyethylene-based resin foam sheet is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

It is preferable to limit the amount of the anionic surfactant to be mixed, while suppressing the formation of lipophilic deposits on the surface of the glass plate 2 until the anionic surfactant sufficiently bleeds out, and accompanying the anionic surfactant to bleed out. This is to suppress the exudation of lipophilic low molecular weight compounds such as oligomers from the inside of the polyethylene-based resin foam sheet.

It is preferable that the total amount of the anionic surfactant and the nonionic surfactant on the surface of the polyethylene-based resin foam sheet in contact with the glass plate 2 is within a predetermined range.

The total amount of the anionic surfactant and the nonionic surfactant on the surface is preferably 1 mg/m 2 or more and 1000 mg/m 2 or less.

Each of the first coating film 11 and the second coating film 12 has a content of the polyoxyethylene alkyl ether type anionic surfactant per unit area (1 m 2) of the extruded foam sheet 10 It is preferably 3 mg/m 2 or more and 100 mg/m 2 or less.

The content of the polyoxyethylene alkyl ether type anionic surfactant in each coating film is more preferably 3 mg/m 2 or more and 80 mg/m 2 or less, and particularly preferably 4 mg/m 2 or more and 50 mg/m 2 or less.

On the other hand, the content of the surfactant per unit area of the coating film can be determined as follows.

(Quantification of surfactant)

A square sample of about 10 cm on one side is cut out from the packaging sheet.

Next, the sample is immersed in 50 ml of distilled water and stored for 40 minutes at 23°C at room temperature to elute the surfactant.

The obtained eluate is measured by a liquid chromatography tandem mass spectrometer (LC-MS/MS), and the concentration (d (%)) of the surfactant in the eluate is calculated based on the calibration curve obtained from the standard solution.

From the concentration (d (%)) and the amount of distilled water used in the eluate (50 ml), the mass of the surfactant (m ₁ (mg) = 50 × d) contained in the eluate is calculated.

The eluted sample is further immersed in 50 ml of distilled water, and the same measurement is performed to determine the mass (m ₂ (mg)) of the surfactant contained in the eluate.

This measurement is repeated until the elution of the surfactant becomes below the detection limit, and the total amount of the surfactant adhered to the test piece (M = m ₁ +m ₂ +...) is calculated.

The surface area of the sample (S: in the above, about 200 cm 2 (about 100 cm 2 × 2 (both sides))) is measured as accurately as possible, and the total amount of surfactant (M) obtained first is divided by the surface area (S) The amount of surfactant per unit area of (M/S) can be calculated.

On the other hand, when it is necessary to measure the first coating film 11 and the second coating film 12 separately, the sample is cut at the center in the thickness direction to produce two sliced pieces, or for one side of the sample. After sufficiently wiping, the same measurement as above may be performed.

In addition, the test conditions for LC-MS/MS can be as follows.

(LC-MS/MS test conditions)

·Used device:

Liquid chromatography tandem mass spectrometer (LC-MS/MS) (model name "UHLC ACCELA" manufactured by Thermo SCIENTIFIC)

·column:

Thermo Hypersil GOLD C18 1.9㎛(2.1mmI.D.*100mmL)

·Measuring conditions:

Column temperature (40°C), mobile phase (A:10mM ammonium acetate/B:acetonitrile=10/90)

·How to create a calibration curve:

Several points of the standard solution of the surfactant to be detected are prepared at a concentration of 0.01 ppm to 10 ppm, measured by LC-MS/MS under the same conditions, and a calibration curve for the detected peak area and the concentration of the standard solution is prepared.

The polyethylene-based resin foam sheet is preferably prepared such that a surfactant is incorporated or a surfactant is coated on the surface to obtain a desired surface resistivity as described above.

It is preferable that the polyethylene-based resin foam sheet in the present embodiment has a surface resistivity of 1×10 ⁶ Ω or more.

The surface resistivity is more preferably 1×10 ⁷ Ω or more, and still more preferably 1×10 ⁸ Ω or more.

The surface resistivity is preferably 1×10 ¹² Ω or less, and more preferably 1×10 ¹¹ Ω or less.

The surface resistivity can be measured by the method described in JIS K6911:1995 "General Test Methods for Thermosetting Plastics".

That is, using a test apparatus (digital ultra-high resistance/microammeter manufactured by Advantest Co., Ltd., model name ``R3840'' and resistance chamber, model name ``R12702A''), in a sample taken from a polyethylene-based resin foam sheet, about The electrode is compressed under a load of 30 N, and the resistance value after charging at 500 V for 1 minute is measured, and calculated by the following equation.

The sample is 100 mm in width x 100 mm in length x thickness (thickness in the state of a foamed polyethylene-based sheet).

The measurement is carried out after conditioning for more than 24 hours in an environment with a temperature of 20±2℃ and a relative humidity of 65±5% RH, and the test environment is a temperature of 20±2℃ and a relative humidity of 65±5% RH.

The number of samples (n number) is 5, and in principle, the front and back sides are measured respectively.

On the other hand, the surface resistivity of each sample is obtained by the following equation, the measured values for all samples are arithmetically averaged, and the average value is taken as the surface resistivity of the polyethylene-based resin foam sheet.

ρs=(π(D+d)/(D-d))×Rs

ρs: Surface resistivity (MΩ)

D: Inner diameter of the surface annular electrode (cm)

d: outer diameter of the inner circle of the surface electrode (cm)

Rs: Surface resistance (MΩ)

In the present embodiment, the polyethylene-based resin foam sheet constituting the packaging sheet 1 is produced by coating the surface of the extruded foam sheet 10 with a coating liquid containing the anionic surfactant.

That is, in the packaging sheet 1 of the present embodiment, a step of coating an extrusion foam sheet 10 with a coating liquid containing an anionic surfactant represented by the formula (1) is performed, and the polyethylene resin foam sheet It can be produced by manufacturing the packaging sheet (1) having the coating film (11, 12) formed of the coating solution on the surface of.

It is preferable that the content per unit area of the anionic surfactant contained in the coating films 11 and 12 of the polyethylene-based resin foam sheet prepared as described above is within a predetermined range.

More specifically, the step of applying the coating solution is preferably carried out so that the content of the anionic surfactant per unit area of the coating film is 3 mg/m 2 or more and 100 mg/m 2 or less.

The formation of the coating films 11 and 12 as described above can be performed continuously with the production of the extruded foam sheet 10.

As described above, the extruded foam sheet 10 according to the present embodiment is manufactured by an extrusion foaming method.

Specifically, the extruded foam sheet 10 is an extrusion process in which the polyethylene-based resin composition is continuously extruded into a sheet form from a circular die mounted at the tip of an extruder to produce an extruded foam sheet, and the extruded sheet is wound. It can be wound up by a machine and manufactured by performing a winding process of manufacturing a sheet roll.

In the said extrusion process in this embodiment, the cylindrical foam continuously extruded from a circular die is air-cooled by spraying cooling air from the inside and outside immediately after extrusion. In the extrusion step in the present embodiment, secondary cooling is performed in which the foam after air cooling (after primary cooling) is further cooled using a cooling mandrel.

In the extrusion process, the cylindrical foam is taken out while cutting in the extrusion direction with a cutter formed on the downstream side of the cooling mandrel.

In the extrusion step in the present embodiment, secondary cooling is performed using a cooling mandrel having an outer diameter larger than the diameter of the circular die.

Accordingly, the secondary cooling is performed by sliding the outer peripheral surface of the cooling mandrel with the inner peripheral surface of the cylindrical foam that has been primary cooled.

In the secondary cooling, while cooling the primary cooled cylindrical foam body, diameter expansion is also performed with a cooling mandrel.

The foam cut in the extrusion direction as described above is unfolded to form a strip, and then wound up to constitute the disk roll.

The coating films 11 and 12 are formed by coating a coating solution on the extruded foam sheet 10 produced as described above.

The coating films 11 and 12 may be formed by performing a coating solution preparation process for preparing a coating solution containing the anionic surfactant and a coating process for coating the coating solution on both surfaces of the extruded foam sheet 10.

The coating of the coating solution may be performed in parallel with the extrusion process, or may be performed again after the extrusion process is completed.

That is, the sheet roll produced in the winding process may be a polyethylene-based resin foam sheet having a coating film formed thereon may be wound in a roll shape, or only the extrusion foam sheet may be wound in a roll shape.

In the coating solution preparation step, a coating solution containing only anionic surfactant may be prepared, or a coating solution containing a solvent for adjusting the viscosity of the coating solution together with an anionic surfactant may be prepared.

The application process may be performed by a general method such as roll coat, kiss coat, spray coat, brushing, and the like.

When coating the coating liquid in parallel with the extrusion process, the coating liquid may be applied from the upstream side of the cooling mandrel or from the downstream side.

Coating of the coating liquid may be performed by spray coating the coating liquid inside and outside the cylindrical foam immediately after extrusion, if necessary. That is, coating of the coating liquid may be performed so as to serve as primary cooling performed before secondary cooling in the cooling mandrel.

In this case, the frictional force generated between the polyethylene-based resin foam sheet (cylindrical foam) and the cooling mandrel can be reduced.

Even as a polyethylene-based resin foam sheet after secondary cooling with a cooling mandrel, its surface temperature is usually higher than room temperature (23°C), so when the coating solution is applied in parallel with the extrusion process, the coating solution may be coated. Even in place, the coating solution is coated on a warm polyethylene-based resin foam sheet.

Then, in the coating film, the anionic surfactant is in a state in which molecular movement is easy, the hydrophilic functional group is easily present in the vicinity of the surface, and it is advantageous in forming a protective film that is easy to wash and remove on the glass plate.

In order to form a coating film on both surfaces of the polyethylene-based resin foam sheet in the above application process, it is not necessary to apply a coating solution to both surfaces of the polyethylene-based resin foam sheet.

For example, a method of forming a coating film on only one side of the polyethylene-based resin foam sheet and transferring a part of the coating liquid to the other side where the coating film is not formed may be employed when the sheet roll is formed.

When the coating process is not carried out in parallel with the extrusion process and is carried out after the extrusion process is finished, the coating liquid can be applied when the sheet roll is rewinded.

The polyethylene-based resin foam sheet has a nonionic surfactant in a state incorporated therein, so that tackiness may occur, but in this embodiment, since the anionic surfactant is coated, the expression of tackiness is suppressed. can do.

In the present embodiment, the extruded foam sheet produced by extrusion foaming is used as the base of the polyethylene resin foam sheet, but the method for producing the polyethylene resin foam sheet is not limited to extrusion foaming.

Further, in the present embodiment, a polyethylene-based resin foam sheet is produced by coating an anionic surfactant on both surfaces of the extruded foam sheet, but coating of an anionic surfactant may be performed on only one side of the extrusion foam sheet.

In addition, in this embodiment, the anionic surfactant is not coated with the anionic surfactant, and the anionic surfactant is mixed in the polyethylene-based resin foam sheet, and the anionic surfactant is bleed on the surface of the polyethylene-based resin foam sheet. You can make it out.

In this embodiment, the case of a single-layer structure in which the sheet for packaging is composed of a single polyethylene-based foam sheet is exemplified, but the sheet for packaging may be a laminated sheet of a plurality of polyethylene-based resin foam sheets.

The sheet for packaging of the present embodiment may be such that a fiber sheet such as a fabric or a metal film is laminated on one side of the polyethylene-based resin foam sheet.

In this embodiment, the case where the packaging sheet is used as a laminate of a glass plate is illustrated, but the use of the packaging sheet of the present invention is not limited to the laminate of a glass plate, and if water washing is scheduled for members other than the glass plate, By using the packaging or the like, the same effect as in the case of using as a laminate of a glass plate can be expected.

That is, the present invention is not limited to the above examples at all.

Example

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Example 1)

As an extruder, a polyethylene-based resin foam sheet was produced using a single-screw extruder with a diameter of 90 mm in the first-stage (upstream side) extruder and a tandem extruder constituted by a single-screw extruder with a diameter of 150 mm in the second-stage (downstream side) extruder.

To 100 parts by mass of the low-density polyethylene resin (density: 931 kg/m 3, MFR = 4.0 g/10 min), the foam modifier master pellet (azodicarbonamide-containing master pellet) is added in a ratio of 0.15 parts by mass. I prepared.

In addition, the blend contains a nonionic surfactant (polyoxyethylene lauryl ether, HLB: about 18) in a proportion of 0.4% by mass, and an anionic surfactant (sodium alkylsulfonate) of 1.0% by mass. It was contained so that it might become a ratio.

The blend was supplied to a hopper of an extruder having a diameter of 90 mm in the first stage, and melt-kneaded so that the maximum temperature reached in the extruder was 210°C.

Further, from the middle of the first extruder, mixed butane (isobutane/normal butane = 50/50 (molar ratio)) as a blowing agent was press-fitted so that the ratio to 100 parts by mass of the low-density polyethylene resin was 18 parts by mass, and added to the extruder. It melt-kneaded by furnace.

The kneaded product obtained by melt-kneading in this first extruder is supplied to the second-stage extruder (cylinder diameter: φ 150 mm) through a connecting pipe, and melt-kneaded in the second extruder to a temperature range (111°C) suitable for foaming. The temperature of the water was lowered.

The melt-kneaded product having the lowered temperature was extruded and foamed in the air with a circular die having a diameter of 222 mm (slit 0.04 mm) connected to the tip of the second extruder to produce a cylindrical foam.

At this time, the resin temperature was 116°C.

The extruded foamed cylindrical foam is cooled by spraying air, then cooled along the top of a cooling mandrel having a diameter of 770 mm and a length of 650 mm, and cut along the extrusion direction with a cutter formed at the rear of the cooling mandrel. It was set as a strip-shaped foam sheet (extrusion foam sheet).

The extruded foam sheet was wound up at a winding speed of 50 m/min, and the extruded foam sheet was made into a roll shape.

That is, a polyethylene-based resin foam sheet in which both a nonionic surfactant and an anionic surfactant were mixed and no polymeric antistatic agent was used was produced by extrusion foaming.

For the obtained polyethylene-based resin foam sheet, the surface resistivity was measured by the method described above, and the case where the surface resistivity was 1×10 ⁷ Ω or more and 1×10 ¹² Ω or less was determined as “○”, and other than that as “×” did.

In addition, among the evaluation items, "tackiness", "basis weight", and "thickness" were evaluated as follows.

(Evaluation of tackiness)

First, a polyethylene-based resin foam sheet was cut into a size of 5 cm x 10 cm to obtain a sample.

Place the sample on the cleaned and dried glass plate (Nippon Electric Glass Co., Ltd. Alkali-free glass OA-10G), place a weight of 1 kg so that a load is applied to the entire sample, and then a constant temperature and humidity tank (manufactured by ISUZU, brand name “HPAV”). -120-40") was heated at 65°C for 48 hours.

The sample after heating was taken out, and after cooling to room temperature, the sample was placed on a flat desk, and the situation at the time of peeling the sample from the glass was determined as follows.

○: There is no adhesion to glass, and only the polyethylene-based resin foam sheet is peeled off without resistance.

(Triangle|delta): When peeling off a polyethylene-type resin foam sheet, although a little glass floats, it falls immediately.

×: The polyethylene-based resin foam sheet and glass are lifted together.

(Measurement method of basis weight)

The basis weight of the polyethylene-based resin foam sheet is obtained by cutting the polyethylene-based resin foam sheet in a width of 20 cm in the extrusion direction in the direction orthogonal to the extrusion direction, and from the mass W (g) and area S (cm 2) of the slice To obtain.

On the other hand, if the width of 20 cm is not large enough to be cut in the direction orthogonal to the extrusion direction, cut it into a rectangular shape to the possible size, and from the mass W (g) and area S (cm 2) of the slice It is obtained by the equation.

Basis weight (g/㎡)＝W/S×10000

Based on the measurement result of the above basis weight and the total sum of nonionic surfactants and anionic surfactants used in the production of the polyethylene resin foam sheet, the amount of surfactant per 1 m2 of the polyethylene resin foam sheet (total surfactant amount) was calculated. I got it.

(thickness)

For the thickness of the polyethylene-based resin foam sheet, using a static pressure thickness meter (manufactured by Teclock, model name “SCM-627”), using a cylindrical weight, and a circular surface (area: 60.8c) with a diameter of 4.4 cm. M2), the thickness of the polyethylene-based resin foam sheet was measured when a 95 g load (including its own weight) was applied to the polyethylene-based resin foam sheet.

On the other hand, 50 points are measured every 5 cm in the width direction, and the arithmetic average value of the measured values is taken as the thickness.

In addition, when a measurement point for 50 points cannot be obtained, it is measured as much as possible, and the arithmetic average value of the measured values is taken as the thickness.

In addition, about the "contact angle" among the evaluation items, it evaluated as follows.

(Measurement of contact angle)

The evaluation of whether the polyethylene-based resin foam sheet obtained in Examples and Comparative Examples had the effect of exerting cleanliness on the glass surface when stored for a long period of time in a packaged state of the display glass was determined by the contact angle after cycle heating as follows. .

First, a polyethylene-based resin foam sheet was cut into a size of 5 cm x 10 cm to obtain a sample.

Place this sample on a washed and dried glass plate (Nippon Electric Glass Co., Ltd.'s alkali-free glass OA-10G), place a weight of 1 kg so that a load is applied to the entire sample, and then use a constant temperature and humidity tank (manufactured by ISUZU Manufacturing Co., Ltd.) , Heating was performed under the brand name "HPAV-120-40").

(Cycle conditions)

The heating in the constant temperature and humidity tank was performed in the following (1) to (4) as one cycle.

(1) Temperature rise from 20℃·60% RH to 60℃·90% RH in 1 hour

(2) Hold for 1 hour at 60℃·90% RH

(3) Temperature decrease from 60℃·90% RH to 20℃·60% RH in 1 hour

(4) Hold for 1 hour at 20℃·60% RH

After the cycle heating test, the sample was removed from the surface of the glass plate, and the glass plate was washed with washing water containing 0.4% of a household alkaline detergent (manufactured by Kao Corporation, brand name "Attack"), followed by rinsing with distilled water, and then at a temperature of 30. It dried at °C and 0% relative humidity for 24 hours.

The contact angle of purified water on the surface of the glass plate in contact with the sample was measured with a solid-liquid interface analyzer (trade name "DROP MASTER300") manufactured by Kyowa Interfacial Chemical Co., Ltd.

On the other hand, the contact angle measured 20 points, respectively, and computed it by the average value.

About the measurement result of the contact angle, it judged with the following three steps.

○: The contact angle was 10 degrees or less.

?: The contact angle was more than 10° and 13° or less.

X: The contact angle exceeded 13 degrees.

(Quantification of fatty acid compounds)

The amount of stearic acid amide contained in the polyethylene-based resin foam sheet was quantified by the method described above (methanol extraction, LC-MS/MS).

(Example 2)

The amount of nonionic surfactant used was 1.0 parts by mass instead of 0.4 parts by mass, the anionic surfactant was changed from sodium alkylsulfonate to sodium polyoxyethylene lauryl ether sulfate, and the anionic surfactant was not mixed. A polyethylene-based resin foam sheet was produced in the same manner as in Example 1, except that the extrusion foam sheet was prepared and then coated on the surface of the extrusion foam sheet.

On the other hand, coating of the anionic surfactant was performed using a spray nozzle immediately before winding up the extruded foam sheet.

Spraying of the anionic surfactant was performed on both sides of the extruded foam sheet, and the amount to be sprayed was carried out so that the ratio of the coated anionic surfactant in the polyethylene resin foam sheet was 0.3% by mass.

(Example 3)

Instead of polyoxyethylene lauryl ether with HLB of about 18, polyoxyethylene alkyl ether (mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether) with HLB of about 16 was used as the nonionic surfactant, 1.5 parts by mass instead of 0.4 parts by mass, the anionic surfactant changed from sodium alkylsulfonate to sodium polyoxyethylene lauryl ether sulfate, and the amount of the anionic surfactant changed from 1.0 parts by mass to 0.5 parts by mass Except that, a polyethylene-based resin foam sheet was produced in the same manner as in Example 1.

(Example 4)

Instead of polyoxyethylene lauryl ether having HLB of about 18, polyoxyethylene alkyl ether (mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether) having HLB of about 16 is used as a nonionic surfactant, and 1.0 mass Anionic surfactant (sodium polyoxyethylene lauryl ether sulfate) is coated on the surface of the extruded foam sheet by spraying after mixing negative anionic surfactant (sodium alkylsulfonate) into the sheet when making the extruded foam sheet Except for the above, a polyethylene-based resin foam sheet was produced in the same manner as in Example 1.

On the other hand, in the coating, the amount to be sprayed was adjusted so that the ratio of the anionic surfactant in the polyethylene-based resin foam sheet was 0.2% by mass.

(Example 5)

A polyethylene-based resin foam sheet was produced in the same manner as in Example 1, except that the amount of the anionic surfactant (sodium alkylsulfonate) was 3.0% by mass instead of 1.0% by mass.

(Comparative Example 1)

A polyethylene-based resin foam sheet was produced in the same manner as in Example 1, except that a nonionic surfactant was not mixed and coated on the surface of the extruded foam sheet.

On the other hand, the amount of the coated nonionic surfactant was set to 0.4% by mass as in Example 1.

(Comparative Example 2)

Without mixing anionic surfactant, only a nonionic surfactant (polyoxyethylene alkyl ether (a mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether) having an HLB of about 16) was mixed, and the ratio A polyethylene-based resin foam sheet was produced in the same manner as in Example 1, except that the amount of the ionic surfactant to be mixed was changed from 0.4% by mass to 2.0% by mass.

(Comparative Example 3)

The same as in Example 1, except that a nonionic surfactant was not mixed, only an anionic surfactant (sodium alkylsulfonate) was mixed, and the amount of the anionic surfactant was changed from 1.0% by mass to 0.4% by mass. Thus, a polyethylene-based resin foam sheet was produced.

(Comparative Example 4)

A polyethylene-based resin foam sheet was produced in the same manner as in Example 1, except that neither a nonionic surfactant nor an anionic surfactant was used.

(Comparative Example 5)

Example 1, except that the nonionic surfactant was replaced by diglycerin monooleate in place of polyoxyethylene lauryl ether, and the amount of the nonionic surfactant was changed from 0.4% by mass to 1.0% by mass. In the same manner as, a polyethylene-based resin foam sheet was produced.

The evaluation results of the polyethylene-based resin foam sheets of each of the Examples and Comparative Examples are shown in the following table.

From the above point of view, it can be seen that the packaging sheet of the present invention is effective in cleaning the surface after washing with water when a glass plate or the like is used as a protection object.

1: Packaging sheet
10: extruded foam sheet
11, 12: Coating film
100: Laminate

Claims (7)

As a packaging sheet provided with a polyethylene-based resin foam sheet composed of a polyethylene-based resin composition,
The polyethylene-based resin foam sheet is provided so as to be exposed on at least one surface of the packaging sheet,
The polyethylene-based resin foam sheet is provided with an anionic surfactant and a nonionic surfactant,
The anionic surfactant is provided in a state coated on the one surface or mixed with the polyethylene-based resin foam sheet, and
The nonionic surfactant is incorporated in the polyethylene-based resin foam sheet,
The sheet for packaging wherein the nonionic surfactant is a polyoxyethylene surfactant having an HLB value of 15 or higher. The method of claim 1,
A packaging sheet having a surface resistivity of 1×10 ⁷ Ω or more and 1×10 ¹² Ω or less on one surface of the polyethylene-based resin foam sheet. The method of claim 1,
The polyethylene-based resin foam sheet is a packaging sheet that does not contain a polymer-type antistatic agent. The method of claim 1,
A packaging sheet, wherein the anionic surfactant is provided in the coated state on the one surface. The method of claim 1,
A packaging sheet in which the total amount of the anionic surfactant and the nonionic surfactant on the one surface is 1 mg/m 2 or more and 1000 mg/m 2 or less. The method of claim 1,
The sheet for packaging wherein the content of the fatty acid compound in the polyethylene-based resin foam sheet is 7 ppm or less. The method of claim 6,
The sheet for packaging wherein the content of stearic acid amide in the polyethylene-based resin foam sheet is 5 ppm or less.

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