TWI815004B - Sheet for packing - Google Patents

Abstract

An objective of the present invention is to provide a sheet for packing capable of keeping the surface of an object to be protected after washing with water in a sufficiently clean state.

As a solution, the sheet for packing of the present invention uses a polyethylene resin foamed sheet in which a polyoxyethylene nonionic surfactant having an HLB value of 15 or more is used in combination with an anionic surfactant.

Description

Packaging tablets

The present invention relates to a packaging sheet, and more specifically, to a packaging sheet including a polyethylene-based resin foam sheet.

Polyethylene-based resin foam sheets are softer and have excellent cushioning properties than polystyrene-based resin foam sheets or polyester-based resin foam sheets.

Therefore, polyethylene resin foam sheets are widely used as packaging sheets for packaging electronic parts, home appliances, glass plates and other items.

This type of packaging sheet is known as a sheet in which a polyethylene resin foam sheet is exposed from the surface in contact with the packaged article, and there are also known sheets that are a polyethylene resin foam sheet alone, or a polyethylene resin foam sheet. The single-area foam sheets include surface-mounted sheets, etc.

This packaging sheet is used as a backing paper inserted between parts when storing components such as glass plates, semiconductor substrates, and metal plates that are the substrates of flat display panels.

In order to prevent foreign matter from adhering to articles such as glass plates and metal plates, antistatic properties are required for packaging sheets used in such lining paper and the like.

Therefore, efforts are being made to develop means for making polyethylene-based resin foam sheets exhibit antistatic properties.

A known method for making a polyethylene resin foam sheet exhibit antistatic properties is to include a polymer-type antistatic agent called a polymer-type antistatic agent or a low-molecular-weight antistatic agent in the material for forming the polyethylene-based resin foam sheet. Molecular antistatic agent and surfactant method.

The surfactant usually oozes onto the surface of the polyethylene-based resin foam sheet to exert antistatic properties.

Therefore, when such a polyethylene resin foam sheet is used as a backing paper for a glass plate, the exuded surfactant will adhere to the surface of the glass plate.

The purpose of using the aforementioned polymeric antistatic agent is to reduce the amount of surfactant added to the polyethylene resin foam sheet and prevent the surfactant from adhering to the glass plate.

Furthermore, as described in Patent Document 1 below, even if a surfactant adheres to an article such as a glass plate, it can be easily removed by washing the article. Rather, the surfactant has a function of effectively cleaning the surface of the article after washing.

[Prior technical literature]

[Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2010-42556.

The use of surfactants is the main reason for the stickiness of polyethylene resin foam sheets.

When using a polyethylene resin foam sheet that has a sticky surface as a packaging sheet, foreign matter may easily adhere to the surface before packaging the items.

Therefore, if a sticky polyethylene-based resin foam sheet is used as a packaging sheet, there is a risk that foreign matter may adhere to the packaged items.

Because of the above situation, it becomes difficult to achieve sufficient cleanliness on the surface of washed items.

However, no particularly effective method for solving such a problem has been found.

Therefore, an object of the present invention is to provide a packaging sheet that can bring the surface of an article to be protected into a sufficiently clean state after being washed with water.

The present inventors diligently reviewed and found that by combining the antistatic properties of polyethylene resin foam sheets with a specific surfactant, a packaging sheet that satisfies the above requirements can be obtained, and the present invention was completed.

In order to solve the above-mentioned problems, the present invention provides a packaging sheet including a polyethylene-based resin foamed sheet composed of a polyethylene-based resin composition, wherein:

The polyethylene resin foam sheet is exposed on at least one surface of the packaging sheet,

The aforementioned polyethylene resin foam sheet contains an anionic surfactant and a nonionic surfactant.

The anionic surfactant is provided in a state of being coated on the surface or kneaded in the polyethylene resin foam sheet,

The aforementioned nonionic surfactant is kneaded in the aforementioned polyethylene resin foam sheet,

The nonionic surfactant is a polyoxyethylene surfactant with an HLB value of 15 or more.

The present invention provides a packaging sheet. Since the polyethylene resin foam sheet contains an anionic surfactant and a specific nonionic surfactant, the surface of the packaged article can be brought into a sufficiently clean state after being washed with water.

1:Packaging sheet

2:Glass plate

10: Extrude foaming sheets

11, 12: Coated film

100:Laminated body

Figure 1 is a schematic diagram showing a usage aspect of the packaging sheet of the present invention.

Figure 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.

The following illustrates a case where the packaging sheet is composed solely of a polyethylene-based resin foam sheet.

In addition, the polyethylene-based resin foam sheet in the state after coating is exemplified below is extruded.

More specifically, the packaging sheet of this embodiment is a polyethylene-based resin foamed sheet, which is extruded and foamed from a polyethylene-based resin composition containing a polyethylene-based resin, whereby the resulting extruded foamed sheet is An anionic surfactant is applied to both sides to form a coating film.

The packaging sheet 1 of this embodiment shown in Figure 1 is used as a backing paper for a glass plate, for example.

The packaging sheet 1 of this embodiment is inserted between adjacent glass plates 2 when a plurality of glass plates 2 are laminated in the up-down direction to form a laminated body 100.

The packaging sheet 1 in this embodiment is composed of a polyethylene resin foam sheet, and the polyethylene resin foam sheet is exposed on both surfaces.

The packaging sheet 1 of this embodiment is as shown in Figure 2. The polyethylene resin foam sheet of the packaging sheet 1 is provided with an extruded foam sheet 10 as a base and a coating formed on the extruded foam sheet. Membranes 11, 12.

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

The packaging sheet 1 of this embodiment includes a first coating film 11 laminated on the first surface of the extruded foam sheet 10 and a second coating film 12 laminated on the second surface opposite to the first surface. .

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

The polyethylene resin composition constituting the polyethylene resin foam sheet of this embodiment may contain the aforementioned polyethylene resin, and examples thereof include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), and low-density polyethylene. Ethylene.

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

The polyethylene resin composition constituting the polyethylene resin foam sheet is not limited to containing only one type of polyethylene resin alone, and may contain two or more types.

The polyethylene resin contained in the polyethylene resin composition is preferably a low-density polyethylene resin.

The aforementioned low-density polyethylene resin is preferably a low-density polyethylene resin (LDPE) with a melt mass flow rate (hereinafter referred to as "MFR") of 2 to 6g/10min and a resin density of 925kg/m3 or ^more and 935kg/ ^m3 or less. ).

Unless otherwise specified in this specification, the above-mentioned melt mass flow rate (MFR) is based on JIS K 7210: 1999 "Melt mass flow rate (MFR) of plastics/thermoplastics" and melt volume flow rate (MVR) test method. It is measured according to the method described in Method B (where the test temperature is 190°C and the load is 21.18N).

The polyethylene resin contained in the extruded foam sheet 10 of this embodiment preferably has the above density, because when the resin density does not reach 925kg/ ^m3 , the foaming agent will escape from the foam sheet quickly after extrusion. , it will reduce the rigidity of the resin itself and may not be able to suppress shrinkage. Moreover, it is preferable to have the above-mentioned density, because if the resin density is set to a value exceeding 935 kg/m ³ , the rigidity of the resin itself becomes too large, and the packaging sheet may not be able to exhibit good cushioning properties.

The polyethylene resin foam sheet of this embodiment includes an anionic surfactant and a nonionic surfactant.

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

That is, the nonionic surfactant is provided in a state of being kneaded in the polyethylene resin foam sheet.

As will be described in detail in the following paragraph, the anionic surfactant is provided in the polyethylene resin foam sheet in a state of being contained in the first coating film 11 and the second coating film 12 .

That is, the polyethylene resin foam sheet contains a nonionic surfactant inside and an anionic surfactant on both surfaces.

Next, the polyethylene resin composition constituting the polyethylene resin foam sheet contains anions constituting the first coating film 11 and the second coating film 12 in addition to the resin composition constituting the extruded foam sheet 10 It is a surfactant.

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

That is, the anionic surfactant may be provided in a state of being coated on the surface of the polyethylene resin foam sheet or kneaded in the polyethylene resin foam sheet.

When kneaded into the polyethylene-based resin foam sheet and provided, the anionic surfactant is contained inside 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 surfactant include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, and the like.

The polyoxyethylene surfactant can be polyoxyethylene fatty acid amide, polyoxyethylene hydrogenated castor oil, etc.

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

Examples of the polyoxyethylene alkyl ether include a hydrophilic portion of polyoxyethylene having a number of 2 to 60 and a lipophilic portion of an alkyl group having a carbon number of 8 to 24, which are ether-bonded through the oxygen atom at the end of the hydrophilic portion. compounds or mixtures thereof.

Specific examples of the polyoxyethylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether. Ether or a mixture of two or more of these, etc.

The polyoxyethylene alkyl ether is in a state of being kneaded in the polyethylene resin foam sheet, thereby exerting the following effect: inhibiting the generation of attachments such as grease and metal soap on the glass plate that cannot be easily removed by washing with water. .

In order to exhibit such an effect significantly, the HLB value of the polyoxyethylene alkyl ether is preferably within a predetermined range.

The HLB of the polyoxyethylene alkyl ether in this embodiment is preferably 15 or more, more preferably 16 or more, and more preferably 17 or more.

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

HLB=20×sum of the formula weights of the hydrophilic part/molecular weight...(A)

Examples of the polyoxyethylene fatty acid ester include polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate, polyoxyethylene oleate, and the like.

Examples of the polyoxyethylene sorbitan fatty acid ester include polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan myristate, polyoxyethylene sorbitan palmitate, and polyoxyethylene sorbitan palmitate. Stearate, polyoxyethylene sorbitan oleate, etc.

Examples of the polyoxyethylene glycerol fatty acid ester include polyoxyethylene glyceryl monolaurate, polyoxyethylene glyceryl monomyristate, polyoxyethylene glyceryl monopalmitate, polyoxyethylene glyceryl monostearate, polyoxyethylene glycerol monostearate, Oxyethylene glycerol monooleate, etc.

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.

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

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

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

The nonionic surfactant is not limited to one type used alone, and two or more types may be mixed and contained in the polyethylene resin composition.

When two or more types of nonionic surfactants are contained, at least one nonionic surfactant may be a polyoxyethylene surfactant whose HLB is the aforementioned value. Preferably, all of the nonionic surfactants are those whose HLB is the aforementioned value. Made of polyoxyethylene surfactant.

When two or more types of nonionic surfactants are contained, the proportion of polyoxyethylene surfactants with HLB of the aforementioned value among all nonionic surfactants is preferably 50 mass % or more, more preferably 70 mass % % or more, and more preferably 90 mass% or more.

When using a plurality of types of nonionic surfactants, it is preferable to include them in the polyethylene resin composition so that the total content value falls within the above numerical range.

Moreover, when the total amount of nonionic surfactant contained is 100 mass %, it is preferable to adjust so that 50 mass % or more may be the said polyoxyethylene alkyl ether.

The ratio of the polyoxyethylene alkyl ether to the nonionic surfactant is more preferably 60 mass% or more, more preferably 70 mass% or more, particularly preferably 80 mass% or more, and particularly preferably 90 mass%. %above.

Examples of the anionic surfactant include alkyl sulfonate, dialkyl sulfonate succinate, α-olefin sulfonate, linear alkyl benzene sulfonate, and naphthalene sulfonate/formaldehyde condensate. , alkyl naphthalene sulfonate, N-methyl-N-acyl taurate and other sulfonate surfactants; aliphatic monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acyl Carboxylate-based surfactants such as sarcosinate and N-acylglutamate; sulfate-based surfactants such as alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfates, and oil sulfate ester salts Phosphate ester salt surfactants such as alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, etc.

In addition, the above-mentioned anionic surfactant is not limited to being used alone, and two or more types may be mixed and used.

The content of the anionic surfactant in the polyethylene resin foam sheet is preferably adjusted to be greater than the content of the nonionic surfactant.

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

Therefore, although the content of the anionic surfactant in the polyethylene resin composition used to produce the extruded foam sheet will vary depending on the content of the anionic surfactant in the coating film, the polyethylene resin composition is based on the content of the anionic surfactant in the coating film. When the vinyl resin content is 100 parts by mass, it is usually from 0.05 to 5.0 parts by mass.

The polyethylene-based resin composition constituting the extruded foam sheet 10 of this embodiment may contain a polymer antistatic agent as an optional component.

Examples of the polymer-type antistatic agent include polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, ethylene/methacrylic acid copolymer plasma polymer, polyethylene glycol, etc. Quaternary ammonium salts such as glycol methacrylate copolymers, copolymers of olefin block and hydrophilic block described in Japanese Patent Application Publication No. 2001-278985, etc.

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

Furthermore, in the packaging sheet according to this embodiment, the reduction in the amount of the polymeric antistatic agent tends to improve the surface cleanliness of the items to be packaged after washing.

Therefore, the aforementioned 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 polymeric antistatic agent at all, and even if it contains it, the content is 1 mass % or less.

The extrusion foam sheet 10 of this embodiment is produced by the extrusion foaming method, so in addition to the above-mentioned components, it may further contain components required for foaming.

The ingredients used for foaming can include foaming agents or bubble regulators.

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

Among them, the aforementioned foaming agent is preferably mixed butane, which is a mixture of isobutane and n-butane.

As mentioned above, if mixed butane is used, isobutane can suppress the rapid escape of the foaming agent in the extrusion step. On the other hand, n-butane, which has excellent compatibility with polyethylene-based resins, can suppress an increase in the open cell ratio. Therefore, an extruded foam sheet 10 with less shrinkage and a small open cell ratio and excellent cushioning properties can be obtained.

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

Usually, the addition ratio of the foaming agent is set in this range because if the foaming agent is less than 5 parts by mass, sufficient foaming will be difficult to obtain, and if it exceeds 25 parts by mass, the bubble film will burst and a good polyethylene resin cannot be obtained. The danger of foaming tablets.

Examples of the bubble adjusting agent used to adjust the bubbles formed by the foaming agent include inorganic powders such as talc and silica. As the bubble regulator, a mixture of a polycarboxylic acid used as a decomposable foaming agent and sodium carbonate or baking soda (sodium bicarbonate), azodicarboxylic acid amide, or the like can also be used.

These can be used individually or in combination of multiple types.

The amount of the bubble regulator added is preferably 0.5 parts by mass or less per 100 parts by mass of the polyethylene resin.

In addition to the above-mentioned components, the extruded foam sheet 10 of this embodiment may also contain additives such as heat stabilizers, ultraviolet absorbers, antioxidants, and colorants, if necessary.

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

That is, the total ratio of polyethylene resin, nonionic surfactant and anionic surfactant in the polyethylene resin foam sheet is preferably 90 mass% or more, more preferably 95 mass% or more, and still more preferably It is more than 98% by mass.

The density (apparent density) of the extruded foam sheet 10 composed of the above-mentioned polyethylene resin composition is not particularly limited, as long as it can exert the cushioning properties required for lining paper of general glass plates, etc., usually Less than 70kg/m ³ , preferably 10kg/m ³ or more and 60kg/m ³ or less.

The reason why the above density can be selected is that when the density is 70 kg/m ^{or more} , the extrusion foam sheet 10 may not have sufficient softness and may reduce its cushioning properties. If the density is too small, the extrusion foam sheet 10 may not have sufficient strength, resulting in Reduce the risk of cushioning.

In addition, if the thickness of the bubble film is too thin, the shrinkage will increase, making it difficult to wind the long extruded foam sheet 10 into a film roll.

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

As mentioned above, the packaging sheet of this embodiment has the coating films 11 and 12 containing an anionic surfactant on both sides of the extruded foam sheet 10.

The type and content of the anionic surfactant contained in the first coating film 11 and the second coating film 12 of the extruded foam sheet 10 may or may not be common.

Since the packaging sheet can be used as a backing paper for a glass plate regardless of the front or back surface, the type or content of the anionic surfactant of the first coating film 11 is preferably the same as that of 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 a packaged article such as a glass plate over a long period of time.

That is, the anionic surfactant is preferably one that is difficult to react with oxygen, moisture, ultraviolet rays, etc. in the air, and that is difficult to lose water solubility.

The first coating film 11 and the second coating film 12 preferably contain an anionic surfactant represented by the following general formula (1).

RO-(CH ₂ -CH ₂ -O) _n -X...(1)

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

H _2m+1 C _m ^- ...(2)

Here, "m" in the general formula (2) is an integer from 1 to 14.

That is, "R-" in the general formula (1) is a univalent group obtained by removing one hydrogen atom from a linear or branched alkane.

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

(a1)-COO ^- M ⁺

(a2)-SO ₃ ^- M ⁺

(a3)-O-SO ₃ ^- M ⁺

(a4)-O-PO(OH)O ^- M ⁺

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

Moreover, "m" in the general 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).

"m" is particularly preferably either 12 or 13.

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

Moreover, the above-mentioned cation (M ⁺ ) is preferably a metal ion such as lithium ion, potassium ion, sodium ion or ammonium ion.

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

The polyoxyethylene alkyl ether type anionic surfactant represented by the general formula (1) is preferably any one of polyoxyethylene sodium lauryl ether sulfate and polyoxyethylene sodium 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 general formula (1) may be contained individually by one type or two or more types.

The first coating film 11 and the second coating film 12 may also contain anionic surfactants other than the polyoxyethylene alkyl ether type anionic surfactant represented by the above general formula (1), but the aforementioned 1. Among the anionic surfactants contained in the coating film 11 and the second coating film 12, it is preferable that 95% by mass or more is the polyoxyethylene alkyl ether type anionic surfactant represented by the above general formula (1) .

Among the anionic surfactants contained in the first coating film 11 and the second coating film 12, the proportion of the polyoxyethylene alkyl ether type anionic surfactant represented by the general formula (1) is particularly preferred. It is more than 98% by mass.

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

The anionic surfactant contained in the coating films 11 and 12 is transferred to the surface of the glass plate 2 through the contact between the glass plate 2 and the packaging sheet 1 as the object to be protected whose surface is protected by the packaging sheet 1. And a hydrophilic protective film is formed on the surface of the glass plate 2 .

Furthermore, in the packaging sheet 1 in this embodiment, the polyoxyethylene-based nonionic surfactant is kneaded into the polyethylene-based resin foam sheet, whereby the generation of low hydrophilic deposits on the glass plate can be suppressed.

Thereby, the glass plate 2 can have a clean surface after being washed with water.

Furthermore, the glass plate 2 can be continuously washed with water for a long time to achieve a clean surface state.

Therefore, even after long-term storage of 3 months or more with the packaging sheet 1 of this embodiment inserted as a backing paper, the surface of the glass plate 2 can be easily cleaned, for example.

In this embodiment, the reason why the coating film contains an anionic surfactant having an alkyl group with the above chain length is that even if it is the same anionic surfactant, if the chain length of the alkyl group becomes longer, the glass plate 2 The protective film on the surface cannot fully exert its hydrophilicity, and it is easy to produce lipophilic attachments on the surface of the glass plate 2 that are more difficult to remove by washing than anionic surfactants.

Furthermore, even if they have alkyl groups with the same chain length, if the surfactant is not an anionic surfactant but a nonionic surfactant, it will be difficult for the protective film on the surface of the glass plate 2 to fully exhibit hydrophilicity.

In order to avoid the generation of lipophilic deposits on the surface of the glass plate 2, the content of the fatty acid compound in the polyethylene resin foam sheet of this embodiment is preferably below a predetermined value.

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, particularly preferably 7 ppm or less.

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

In the polyethylene-based resin foam sheet, the content of stearic acid amide in the fatty acid compound is preferably less than or equal to a predetermined value.

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

The content of stearamide in the polyethylene resin foam sheet is particularly preferably 4 ppm or less.

Fatty acid compounds are sometimes contained in commercially available resin particles as external lubricants or internal lubricants for polyethylene resins.

Therefore, when using a commercially available product as the polyethylene resin contained in the polyethylene-based resin foam sheet, it is preferable to use a fatty acid compound having the above content.

That is, the content of the fatty acid compound in the polyethylene resin is preferably 10 ppm or less, more preferably 9 ppm or less, still more preferably 8 ppm or less, 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.

Moreover, the content of amide stearate in the polyethylene-based resin is preferably 7 ppm or less, more preferably 6 ppm or less, and still more preferably 5 ppm or less.

The content of amide stearate in the polyethylene resin is particularly preferably 4 ppm or less.

In this embodiment, the anionic surfactant or the nonionic surfactant is present on the surface of the polyethylene resin foam sheet, so that the fatty acid compounds can be contained in the polyethylene resin foam sheet. Inhibits fatty acid compounds from adhering to packaged items.

However, in order to more reliably prevent the fatty acid compound from adhering, the content of the fatty acid compound is preferably the above value.

When the aforementioned anionic surfactant or the aforementioned nonionic surfactant is kneaded into the extruded foam tablet, the mother containing the surfactant is utilized at a higher concentration than the concentration of the surfactant in the extruded foam tablet. Those with granules are effective.

When producing an extruded foam sheet using a masterbatch containing the anionic surfactant or the nonionic surfactant, extrusion is usually performed using mixed particles of polyethylene resin particles and a masterbatch that do not contain the surfactant. Lather.

At this time, when the masterbatch ratio in the total of the masterbatch and polyethylene resin particles is set to "X(%)" and the masterbatch dilution ratio is set to "Y(times)", "X(%) ” and “Y (times)” roughly establish the following relationship.

Y=(100/X)

Therefore, when the masterbatch is diluted with polyethylene-based resin particles that do not contain the fatty acid compound, the fatty acid compound may be contained in the masterbatch at a ratio that is Y times the aforementioned content.

This condition is the same not only when the extruded foam sheet contains a surfactant using a master batch, but also when the extruded foam sheet contains various additives using a master batch.

The fatty acid compound functions as an external lubricant to suppress excessive friction between the inner wall surface of the cylinder of the extruder or the threads of the screw and the resin melted and kneaded in the extruder.

In this embodiment, a masterbatch containing a surfactant at a high concentration is used, whereby a portion of the surfactant is expected to bleed out from the masterbatch and function as an external lubricant inside the extruder.

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

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

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

It is difficult to contain the surfactant in the masterbatch at an excessive ratio, so the surfactant content is preferably 15 mass% or less, more preferably 10 mass% or less.

Examples of the fatty acid compound in this embodiment include fatty acids, fatty acid metal salts, fatty acid amide, fatty acid esters, and the like.

Specific examples of fatty acids include saturated fatty acids such as lauric acid, palmitic acid, stearic acid, and behenic acid, and unsaturated fatty acids such as oleic acid, sinapic acid, linoleic acid, and sublinolenic acid. In addition to these Examples of monocarboxylic acids include dicarboxylic acids such as dimer acid.

Examples of metals constituting the fatty acid metal salt include calcium, magnesium, aluminum, zinc, and the like.

Fatty acid amide refers to acid amide derived from fatty acids.

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

Specific examples of fatty acid amide include stearic acid amide, palmitic acid amide, oleic acid amide, sinapic acid amide, methylene distearic acid amide, ethyl distearic acid amide, Ethyl dioleic acid amide, ethyl bishydroxystearic acid amide, etc.

Specific examples of fatty acid esters include butyl stearate, stearic acid monoglyceride, oleic acid monoglyceride, behenic acid monoglyceride, linoleic acid monoglyceride, and castrate monoglyceride. , hydroxystearic acid triglyceride, sorbitan fatty acid ester, polyoxyethylene (5) glyceryl monostearate, polyoxyethylene (20) glyceryl monostearate, polyoxyethylene (5) monostearate Oleate, neopenterythritol tetrastearate, polyneopenterythritol adipate, stearyl stearate, 1,2-hydroxystearic acid, hydrogenated castor oil, etc.

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

Examples of the method include the following methods.

The fatty acid metal salt is measured in the following manner, for example.

Dip the polyethylene resin foam sheet into boiling methanol and extract. After cooling, the precipitated sediments are filtered out. Suspending the precipitate in dilute hydrochloric acid and using ether for solvent extraction will extract the fatty acids free in the ether phase and the metals free in the water phase. Therefore, fatty acids can be quantified by the method described below, and metals can be quantified by ICP. (Inductively coupled plasma) luminescence analysis device, etc. are used to identify and quantify metal species.

The aforementioned fatty acid, the aforementioned fatty acid amide, and the aforementioned fatty acid ester can be quantified using a liquid chromatography tandem mass spectrometer (LC-MS/MS) (for example, Termo SCIENTIFIC Corporation "ACCELA").

Furthermore, five types of standard solutions with different concentrations (5ppm, 2ppm, 1ppm, 0.5ppm, 0.2ppm), and use these standard solutions to prepare calibration lines used when quantifying fatty acid compounds.

In addition, the sample prepared in LC-MS/MS was prepared in the following manner.

． Cut the polyethylene resin foam sheet into a size of approximately 2 mm square and collect approximately 0.15 g of extraction sample.

． The extraction sample was accurately weighed, and the extraction sample and 10 ml of methanol were put into a pressure-resistant container made of PTFE (polytetrafluoroethylene), and the pressure-resistant container was sealed.

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

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

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

． The amount of the fatty acid compound in the filtrate was calculated from the measurement results using the previously determined calibration curve.

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

In this embodiment, it is preferable that the anionic surfactant as described above is not allowed to ooze out from the inside of the polyethylene resin foam sheet, but is maintained in a coated film state on the surface of the polyethylene resin foam sheet.

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

The kneading amount (mass) of the anionic surfactant in the polyethylene resin foam sheet is specifically preferably 1 mass% or less, more preferably 0.5 mass% or less.

It is preferable to limit the amount of kneading of the anionic surfactant in order to suppress the generation of lipophilic attachments on the surface of the glass plate 2 before the anionic surfactant fully bleeds out, and at the same time to suppress the infiltration of the anionic surfactant from the surface. Polyethylene-based resin foam sheet contains oligomers and other lipophilic low molecular weight compounds exuded from inside.

The total amount of the anionic surfactant and the nonionic surfactant on the surface of the polyethylene resin foam sheet before being in contact with the glass plate 2 is preferably within a predetermined range.

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

In each of the first coating film 11 and the second coating film 12, the content of the polyoxyethylene alkyl ether type anionic surfactant per unit area (1 m ² ) of the extruded foam sheet 10 is relatively high. The preferred range is 3 mg/m ² or more and 100 mg/m ² or less.

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

In addition, the content of the surfactant per unit area of the coating film can be determined in the following manner.

(Quantification of surfactant)

Cut out a square sample of about 10cm from one side of the packaging sheet.

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

The resulting washing liquid was measured with liquid chromatography tandem mass spectrometry (LC-MS/MS), and the concentration (d(%)) of the surfactant in the washing liquid was calculated based on the calibration line obtained from the standard solution.

Calculate the mass of the surfactant contained in the washing liquid (m ₁ (mg) = 50 × d) from the concentration (d (%)) and the amount of distilled water used in the washing liquid (50 ml).

The eluted sample was again immersed in 50 ml of distilled water and the same measurement was performed to determine the mass (m ₂ (mg)) of the surfactant contained in the washing liquid.

Repeat this measurement until the dissolution of the surfactant reaches below the detection limit, and determine the total amount of surfactant attached to the test piece (M=m ₁ +m ₂ +...).

Determine the surface area (S: approximately 200cm ² (approximately 100cm ² × 2 (both sides))) of the aforementioned sample as accurately as possible, and divide the previously obtained total amount of surfactant (M) by the aforementioned surface area (S ), and the surfactant dose per unit area of the coating film (M/S) can be obtained.

Furthermore, when it is necessary to separately measure the first coating film 11 and the second coating film 12, it is sufficient to cut the sample at the center in the thickness direction and prepare two slices, or to sufficiently wipe one side of the sample before performing the above measurement.

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

(LC-MS/MS test conditions)

． Using device:

Liquid chromatography tandem mass spectrometer (LC-MS/MS) (model "UHLCACCELA" manufactured by Thermo SCIENTIFIC Co., Ltd.)

． Pipe string:

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

． Measurement conditions:

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

． How to make the calibration line:

Make several points of the standard solution of the surfactant to be tested at a concentration between 0.01ppm and 10ppm, measure it by LC-MS/MS under the same conditions, and make a calibration line of the detected peak area and the concentration of the standard solution.

The aforementioned polyethylene resin foam sheet is preferably prepared as follows: kneading the surfactant in the above manner or coating the surfactant on the surface to form the required surface resistivity.

The surface resistivity of the polyethylene-based resin foam sheet in this embodiment is preferably 1×10 ⁶ Ω or more.

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

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

Surface resistivity can be measured by the method described in JIS K 6911: 1995 "General test methods for thermosetting plastics".

That is, using a test device (digital ultra-high resistance/minimum current meter manufactured by Advantest Co., Ltd., product name "R3840" and Resistivity Chamber, product name "R12702A"), a sample collected from a polyethylene-based resin foam sheet was measured at approximately Press the electrode with a load of 30N, measure the resistance value after charging at 500V for 1 minute, and calculate it according to the following formula.

The sample has a width of 100 mm, a length of 100 mm, and a thickness (original thickness of the polyethylene-based resin foam sheet).

The measurement is carried out after conditioning for more than 24 hours at a temperature of 20±2℃ and a relative humidity of 65±5%RH. 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 separately.

Furthermore, the surface resistivity of each sample was determined according to the following formula, the measured values of all samples were calculated and averaged, and the average value was used as the surface resistivity of the polyethylene resin foam sheet.

ρs=(π(D+d)/(D-d))×Rs

ρs: surface resistivity (MΩ)

D: Inner diameter of the ring electrode on the surface (cm)

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

Rs: surface resistance (MΩ)

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

That is, the packaging sheet 1 of this embodiment can be produced by applying the coating liquid containing the anionic surfactant represented by the general formula (1) to the extruded foam sheet 10, and The packaging sheet 1 is produced by having the coating films 11 and 12 formed of the coating liquid on the surface of the polyethylene-based resin foam sheet.

The content per unit area of the aforementioned anionic surfactant contained in the coating films 11 and 12 of the polyethylene-based resin foam sheets produced in the above-mentioned manner is preferably within a predetermined range.

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

The above-mentioned coating films 11 and 12 can be formed continuously during the production of the extruded foam sheet 10 .

As mentioned above, the extrusion foamed sheet 10 of this embodiment is manufactured by the extrusion foaming method.

Specifically, the extruded foam sheet 10 can be produced by performing the following steps: continuously extruding and foaming the polyethylene-based resin composition into a sheet shape using a circular die or the like installed at the front end of the extruder. The extrusion step of the foamed sheet; and the winding step of winding the extruded sheet through a winding machine to produce a sheet roll.

In the aforementioned extrusion step in this embodiment, the cylindrical foam is continuously extruded from the circular die, and cooling air is blown from inside and outside immediately after extrusion to perform primary air cooling. In the aforementioned extrusion step in this embodiment, the foam after air cooling (after primary cooling) is further cooled using a cooling mandrel to perform secondary cooling.

In the aforementioned extrusion step, a cutter provided on the downstream side of the cooling mandrel is used to cut and pull the cylindrical foam in the extrusion direction.

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

Therefore, this secondary cooling is implemented by sliding the outer peripheral surface of the cooling mandrel to the inner peripheral surface of the primary-cooled cylindrical foam.

In this secondary cooling, the cylindrical foam that has been cooled once is cooled and simultaneously expanded in diameter using a cooling mandrel.

As mentioned above, after the foaming system cut by cutting and cutting in the extrusion direction is unfolded into a strip shape, it is wound and formed into the aforementioned raw material roll.

The coating films 11 and 12 are formed by applying the coating liquid to the extruded foam sheet 10 produced in this way.

The coating films 11 and 12 are obtained by performing the following steps: a coating liquid preparation step of preparing a coating liquid containing the anionic surfactant; and a coating step of applying the coating liquid to both sides of the extruded foam sheet 10 .

The coating liquid can be applied simultaneously with the extrusion step or after the end of the extrusion step.

That is, the sheet roll produced in the winding step may be one in which the polyethylene-based resin foam sheet on which the coating film is formed is wound into a roll, or one in which only the extruded foam sheet is wound in the shape of a roll.

In the aforementioned coating liquid preparation step, a coating liquid containing only an anionic surfactant may be prepared, or a coating liquid containing an anionic surfactant and a solvent for adjusting the viscosity of the coating liquid may be prepared.

The aforementioned coating step can be implemented by general methods such as roller coater, contact coater, spray coater, and brushing.

When the application of the coating liquid and the extrusion step are performed simultaneously, the application of the coating liquid may be performed upstream or downstream of the cooling mandrel.

If necessary, the coating liquid can be applied by spraying the coating liquid inside and outside the extruded cylindrical foam. That is, the coating liquid can be applied in a manner that combines the primary cooling performed before the secondary cooling of the cooling mandrel.

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

Even if the polyethylene resin foam sheet is cooled twice by the cooling mandrel, the surface temperature is usually higher than normal temperature (23°C). Therefore, when the application and extrusion steps of the coating liquid are performed at the same time, no matter what The coating liquid is applied at the position, and the coating liquid is also applied to the polyethylene resin foam sheet in a warm state.

In this way, in the coating film, the anionic surfactant becomes a state in which the molecules can easily move, and the hydrophilic functional groups can easily exist densely near the surface, which is advantageous for forming a protective film on the glass plate that is easily removed by water washing.

In the aforementioned coating step, in order to form coating films on both sides of the polyethylene resin foam sheet, it is not necessary to apply the coating liquid to both sides of the polyethylene resin foam sheet.

For example, the following method can be used: forming a coating film on only one side of the polyethylene resin foam sheet, forming a sheet roll, and then transferring part of the coating liquid to the other side where the coating film is not formed.

When the coating step is not performed simultaneously with the extrusion step, but is performed after the extrusion step, the coating liquid can be applied when the sheet roll is replaced.

The aforementioned polyethylene-based resin foam sheet contains a nonionic surfactant in a state of being kneaded inside, which may cause stickiness. However, in this embodiment, the anionic surfactant is coated, so the stickiness can be suppressed. show.

In this embodiment, an extrusion foamed sheet manufactured by extrusion foaming is used as the base of the polyethylene resin foam sheet, but the manufacturing method of the polyethylene resin foam sheet is not limited to extrusion foaming.

Furthermore, in this embodiment, the anionic surfactant is applied to both sides of the extruded foam sheet to produce a polyethylene resin foam sheet. However, the anionic surfactant may be applied only to one side of the extruded foam sheet. face implementation.

Furthermore, in this embodiment, it is possible to knead the anionic surfactant in the polyethylene resin foam sheet without applying the anionic surfactant, and to allow the anionic surfactant to infiltrate into the polyethylene resin. Foam sheet surface.

This embodiment exemplifies the case where the packaging sheet has a single-layer structure composed of a single polyethylene resin foam sheet, but the packaging sheet may have a plurality of laminated polyethylene resin foam sheets.

The packaging sheet of this embodiment may be a polyethylene-based resin foam sheet laminated with a fiber sheet such as fabric or a metal film on a single surface.

This embodiment illustrates the use of a packaging sheet as a lining paper for a glass plate. However, the use of the packaging sheet of the present invention is not limited to a lining paper for a glass plate. It can be used as a member other than a glass plate as long as it is intended to be used. Those who wash it with water can expect the same effect as when used as a backing paper for glass plates by using it for packaging.

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

(Example)

Next, the present invention will be described in further detail using examples, but the present invention is not limited to these.

(Example 1)

The extruder is composed of a single-screw extruder with a diameter of 90mm in the first stage (upstream side) and a single-screw extruder with a diameter of 150mm in the second stage (downstream side). Extruders are connected in series to produce polyethylene resin foam sheets.

Prepare 100 parts by mass of low-density polyethylene resin (density: 931kg/m ³ , MFR=4.0g/10min) and add a bubble adjuster masterbatch (masterbatch containing azodimethylamide) at a ratio of 0.15 parts by mass. admixtures.

Furthermore, this blend contains a nonionic surfactant (polyoxyethylene lauryl ether, HLB: about 18) at a rate of 0.4% by mass, and an anionic surfactant (alkane) at a rate of 1.0% by mass. sodium sulfonate).

The aforementioned blend was supplied to the hopper of an extruder with a diameter of 90 mm in the first stage, and was melt-kneaded until the maximum temperature in the extruder became 210°C.

Furthermore, mixed butane (isobutane/n-butane=50/50 (mol ratio)) as a blowing agent was added from the first extruder at an amount of 100 parts by mass relative to the low-density polyethylene resin. It was pressed so that the ratio became 18 parts by mass, and further melt-kneaded in this extruder.

The kneaded product obtained by the melt-kneading of the first extruder is supplied to the second-stage extruder (cylinder diameter: φ150 mm) through the connecting pipe, and the temperature of the melt-kneaded product is adjusted in the second extruder. Lower to the temperature range suitable for foaming (111°C).

The molten kneaded material whose temperature has been lowered is extruded and foamed into the atmosphere from a circular die with a diameter of 222 mm (slit 0.04 mm) connected to the front end of the second extruder to produce a cylindrical foam.

The resin temperature at this time is 116°C.

After the extrusion-foamed cylindrical foam is cooled by blowing air, it is cooled along a cooling mandrel with a diameter of 770 mm and a length of 650 mm, and a cutter installed on the rear side of the cooling mandrel is extruded along the It is cut in the direction to form a long strip-shaped foam sheet (extrusion foam sheet).

The extruded foamed sheet was wound at a winding speed of 50 m/min to form a roll.

That is, both a nonionic surfactant and an anionic surfactant are kneaded, and foamed by extrusion to produce a polyethylene resin foam sheet that does not use a polymeric antistatic agent at all.

The surface resistivity of the obtained polyethylene-based resin foam sheet was measured by the method described above. When the surface resistivity was 1×10 ⁷ Ω or more and 1×10 ¹² Ω or less, it was judged as "○", and otherwise it was judged as "×" ”.

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

(evaluation of stickiness)

First, the polyethylene-based resin foam sheet was cut into a size of 5 cm × 10 cm to serve as a sample.

The sample was placed on a washed and dried glass plate (alkali-free glass OA-10G manufactured by Nippon Electric Glass Co., Ltd., a 1kg weight was placed to apply a load to the entire sample, and placed in a constant temperature and humidity chamber (manufactured by ISUZU Seisakusho Co., Ltd. Brand name "HPAV-120-40") was heated at 65°C for 48 hours.

After taking out the heated sample and cooling it to room temperature, place the sample on a flat table and determine the conditions when the sample is peeled off from the glass in the following manner.

○: There is no adhesion to the glass, only the polyethylene resin foam sheet is peeled off smoothly.

△: When peeling off the polyethylene-based resin foam sheet, the glass was slightly raised but separated immediately.

×: The polyethylene-based resin foam sheet was pulled up together with the glass.

(Measurement method of unit weight)

The basis weight of the polyethylene resin foam sheet is determined by cutting the polyethylene resin foam sheet with a width of 20cm along the extrusion direction in the direction orthogonal to the extrusion direction, and calculating the slice mass W (g) and area S (cm ² ) is determined by the following formula.

Also, if the size is not enough to be cut into a 20cm width in the direction perpendicular to the extrusion direction, cut it into a rectangular shape as large as possible, and calculate it from the following formula based on the slice mass W (g) and area S (cm ² ) out.

Unit weight (g/m ² )=W/S×10000

The weight per 1 m ² of the polyethylene resin foam sheet is calculated based on the above measurement results of the basis weight and the total number of nonionic surfactants and anionic surfactants used in the production of the polyethylene resin foam sheet. Surfactant dose (total surfactant dose).

(thickness)

The thickness of the polyethylene resin foam sheet is measured using a constant pressure thickness measuring machine (model "SCM-627" manufactured by Teclock Co., Ltd.) using a cylindrical gauge on a circular surface with a diameter of 4.4cm (area: 60.8cm ² ) , a load of 95g (including its own weight) is applied to the polyethylene resin foam sheet, and the thickness of the polyethylene resin foam sheet at this time is measured.

In addition, 50 points were measured every 5 cm in the width direction, and the arithmetic mean of the measured values was used as the thickness.

In addition, when 50 measurement points cannot be obtained, the thickness shall be measured as much as possible and the arithmetic mean of the measured values shall be used as the thickness.

Furthermore, the "contact angle" among the evaluation items is evaluated in the following manner.

(Measurement of contact angle)

In the state where the polyethylene resin foam sheets obtained in Examples and Comparative Examples were packed with display glass, the contact angle after cyclic heating was determined in the following manner to evaluate whether the glass surface has a cleaning effect during long-term storage.

First, the polyethylene-based resin foam sheet was cut into a size of 5 cm × 10 cm and used as a sample.

The sample was placed on a washed and dried glass plate (alkali-free glass OA-10G manufactured by Nippon Electric Glass Co., Ltd.), and a weight of 1 kg was placed to apply a load to the entire sample, and placed in a constant temperature and humidity chamber (ISUZU Manufacturing Co., Ltd. The company's brand name "HPAV-120-40") is heated.

(loop condition)

The heating of the constant temperature and humidity chamber is performed with the following (1) to (4) as one cycle.

(1) Raise the temperature from 20℃, 60%RH to 60℃, 90%RH in 1 hour

(2) Keep at 60℃, 90%RH for 1 hour

(3) Cool down from 60℃, 90%RH to 20℃, 60%RH in 1 hour

(4) Keep at 20℃, 60%RH for 1 hour

The sample was removed from the surface of the glass plate after the above-mentioned cyclic heating test, and the glass plate was washed with clean water containing 0.4% of a household alkali detergent (manufactured by Kao Co., Ltd., trade name "Attack"), and washed with distilled water. , dry for 24 hours at a temperature of 30°C and a relative humidity of 0%.

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

Furthermore, the contact angle was measured at 20 points and the average value was calculated.

The measurement results of the contact angle are judged in the following three stages.

○: The contact angle is 10° or less.

△: The contact angle is more than 10° and less than 13°.

×: The contact angle exceeds 13°.

(Quantification of fatty acid compounds)

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

(Example 2)

The usage amount of the nonionic surfactant was changed from 0.4 parts by mass to 1.0 parts by mass, the anionic surfactant was changed from sodium alkyl sulfonate to sodium polyoxyethylene lauryl ether sulfate, and the anionic surfactant was not kneaded. After preparing the extruded foam sheet, the agent was applied to the surface of the extruded foam sheet, and a polyethylene resin foam sheet was prepared in the same manner as in Example 1.

Furthermore, the anionic surfactant is applied using a spray nozzle before winding and extruding the foamed sheet.

The anionic surfactant is sprayed on both sides of the extruded foam sheet, and the amount of spray is such that the proportion of the coated anionic surfactant in the polyethylene resin foamed sheet becomes 0.3% by mass. way to implement.

(Example 3)

The nonionic surfactant was changed from polyoxyethylene lauryl ether with an HLB of approximately 18 to polyoxyethylene alkyl ether with an HLB of approximately 16 (a mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether). Change the usage amount from 0.4 parts by mass to 1.5 parts by mass, change the anionic surfactant from sodium alkyl sulfonate to sodium polyoxyethylene lauryl ether sulfate, and change the kneading amount of the anionic surfactant from 1.0 mass A polyethylene-based resin foam sheet was produced in the same manner as in Example 1 except that the part was changed to 0.5 parts by mass.

(Example 4)

Change the nonionic surfactant from polyoxyethylene lauryl ether with an HLB of approximately 18 to polyoxyethylene alkyl ether with an HLB of approximately 16 (a mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether) 1.0 parts by mass of the anionic surfactant (sodium alkyl sulfonate) is kneaded into the sheet when producing the extruded foam sheet, and then the anionic surfactant (polyoxyethylene laurel) is further sprayed on the surface of the extruded foam sheet. A polyethylene-based resin foam sheet was produced in the same manner as in Example 1 except that sodium ether sulfate was used.

In addition, during the above-mentioned coating, the spray amount was adjusted so that the ratio of the anionic surfactant in the polyethylene resin foam sheet became 0.2% by mass.

(Example 5)

A polyethylene resin foam sheet was produced in the same manner as in Example 1 except that the amount of anionic surfactant (sodium alkyl sulfonate) was changed from 1.0 mass % to 3.0 mass %.

(Comparative example 1)

A polyethylene-based resin foamed sheet was produced in the same manner as in Example 1, except that the nonionic surfactant was applied to the surface of the extruded foamed sheet without kneading.

In addition, the amount of nonionic surfactant applied was 0.4% by mass, the same as in Example 1.

(Comparative example 2)

Instead of kneading the anionic surfactant, knead only the nonionic surfactant (polyoxyethylene alkyl ether (a mixture of polyoxyethylene oleyl ether and polyoxyethylene cetyl ether) with an HLB of approximately 16), and A polyethylene resin foam sheet was produced in the same manner as in Example 1 except that the kneading amount of the nonionic surfactant was changed from 0.4 mass % to 2.0 mass %.

(Comparative example 3)

The nonionic surfactant is not kneaded but only the anionic surfactant (sodium alkyl sulfonate) is kneaded, and the kneading amount of the anionic surfactant is changed from 1.0 mass % to 0.4 mass %. In addition, A polyethylene-based resin foam sheet was produced in the same manner as in Example 1.

(Comparative example 4)

A polyethylene resin foam sheet was produced in the same manner as in Example 1, except that the nonionic surfactant and the anionic surfactant were not used.

(Comparative example 5)

The nonionic surfactant was changed from polyoxyethylene lauryl ether to diglyceryl monooleate, and the kneading amount of the nonionic surfactant was changed from 0.4% by mass to 1.0% by mass. In addition, the same as A polyethylene resin foam sheet was produced in the same manner as in Example 1.

The evaluation results of the polyethylene resin foam sheets of each Example and Comparative Example are shown in the table below.

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

1:Packaging sheet

10: Extrude foaming sheets

11, 12: Coated film

Claims (7)

A packaging sheet comprising a polyethylene resin foam sheet made of a polyethylene resin composition, wherein the polyethylene resin foam sheet is exposed on at least one surface of the packaging sheet, and the polyethylene resin foam sheet is exposed on at least one surface of the packaging sheet. The resin foam sheet is provided with an anionic surfactant and a nonionic surfactant. The anionic surfactant is coated on the surface or kneaded on the polyethylene resin foam sheet. It is provided that the aforementioned nonionic surfactant is kneaded in the aforementioned polyethylene resin foam sheet, the nonionic surfactant is a polyoxyethylene surfactant with an HLB value of 15 or more, and the aforementioned polyethylene resin foam sheet does not Contains a polymeric antistatic agent, or the polyethylene resin composition contains 1 mass % or less of a polymeric antistatic agent. The packaging sheet according to claim 1, wherein the surface resistivity of the polyethylene resin foam sheet on the one surface is 1×10 ⁷ Ω or more and 1×10 ¹² Ω or less. The packaging sheet described in Item 1 of the patent application, wherein the polyethylene resin foam sheet does not contain a polymeric antistatic agent. The packaging sheet according to claim 1, wherein the anionic surfactant is provided in a state of being coated on the surface. The packaging sheet according to claim 1, wherein 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 packaging sheet according to claim 1, wherein the content of stearamide in the polyethylene resin foam sheet is 5 ppm or less. The packaging sheet according to any one of claims 1 to 6, wherein the content of the fatty acid compound in the polyethylene resin foam sheet is 7 ppm or less.

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