KR102392882B1 - Packaging sheet - Google Patents

Abstract

An object of the present invention is to provide a sheet for packaging that has little transfer of components to an object to be packaged and is excellent in antistatic properties. A polyolefin-based resin foam sheet containing a donor-acceptor-type antistatic agent is provided in the packaging sheet.

Description

Sheet for packaging {PACKAGING SHEET}

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

Conventionally, polyolefin-based resin foam sheets have been widely used as packaging sheets and the like because they are flexible compared to polystyrene-based resin foam sheets, polyester-based resin foam sheets, and the like, and have excellent cushioning properties.

As this type of packaging sheet, a single polyolefin-based resin foam sheet, a laminated sheet in which a polyolefin-based resin foam sheet is laminated with a packaging sheet, and the like are known.

As a to-be-packed object packaged with this type of sheet|seat for packaging, an electric machine, an electronic device, or the member for electric machines, the member for electronic devices, etc. which comprise these are known.

The packaging sheet is used for the purpose of protecting the object to be packaged from impact during storage or transportation, and when storing members such as glass plates, semiconductor substrates, and metal plates that are substrates of flat display panels, it is also used as a paper inserted between the members. is being used

Such a sheet for packaging may be required to have antistatic properties so that an object to be packaged is not adhered by static electricity.

As a method of making the polyolefin resin foam sheet exhibit antistatic properties, a polymer type antistatic agent called a polymer type antistatic agent and a surfactant called a low molecular type antistatic agent are contained in the forming material of the polyolefin resin foam sheet How to do it is known.

Among these, in order to exhibit antistatic property by bleed-out to a sheet|seat surface, about surfactant, it adheres easily to the surface of an object to be protected (refer following patent document 1).

On the other hand, the polymer-type antistatic agent contains metal ions in many cases, and there is a fear that the metal ions migrate to such a to-be-packaged object and adversely affect it.

Japanese Patent Laid-Open No. 2010-42556

In view of the above, the sheet for packaging is required to exhibit antistatic properties and to have less transfer of components to the object to be packaged, but these requirements are not satisfied.

Accordingly, it is an object of the present invention to provide a sheet for packaging that has little transfer of components to an object to be packaged and is excellent in antistatic properties.

As a result of earnest examination to solve the above problems, the present inventors found that the polyolefin-based resin foam sheet containing the donor acceptor type antistatic agent exhibits excellent antistatic properties, and metal ions transfer and bleed-out occur. The following difficulties were found and the present invention was completed.

That is, in order to solve the above problems, the present invention,

A packaging sheet comprising a polyolefin-based resin foam sheet containing a donor-acceptor-type antistatic agent, wherein the polyolefin-based resin foam sheet is exposed on at least one surface.

In the polyolefin resin foam sheet containing a donor-acceptor type antistatic agent, since a donor, such as a boron compound, and an acceptor, such as a nitrogen compound, coexist, the diffusion of holes and electrons are rapidly performed, so sodium ions and lithium ions Good antistatic properties are exhibited even if the action of metal ions, such as these is not used.

Moreover, in the polyolefin resin foam seat|seet containing a donor-acceptor type antistatic agent, even if it does not contain the compound which causes bleed-out, such as surfactant, favorable antistatic property is exhibited.

Therefore, in the packaging sheet provided with such a polyolefin resin foam sheet exposed on at least one surface, excellent antistatic properties can be exhibited while suppressing migration of components to the object to be packaged.

1 is a schematic diagram showing a usage mode of a sheet for packaging.
2 is a schematic cross-sectional view of a sheet for packaging according to an embodiment of the present invention.
3 is a schematic view showing another embodiment of the sheet for packaging.

The packaging sheet of the present invention will be described.

Hereinafter, an embodiment of the present invention will be described with an example in which the packaging sheet is a single-layer sheet composed of only a polyolefin-based resin foam sheet, and the front and back surfaces are composed of a polyolefin-based resin foam sheet as an example.

In addition, below, the case where the said polyolefin resin foam seat|seet is an extruded foam is illustrated.

More specifically, in the following, a packaging sheet provided with a polyolefin-based resin foam sheet formed by extruding and foaming a polyolefin-based resin composition containing a polyolefin-based resin is used as a bag of electronic components or as a paper for a glass plate while exemplifying the case EMBODIMENT OF THE INVENTION Embodiment of this invention is described.

1 shows a state in which the packaging sheet of this embodiment is used as a constituent material of the packaging bag 100 for accommodating the printed circuit board X1.

The packaging bag 100 of the present embodiment is composed of two packaging sheets, a rectangular topsheet 100a and a backsheet 100b having a larger area than the printed circuit board X1.

In the packaging bag 100 of the present embodiment, a three-way sealing is applied to a laminate in which the top sheet 100a and the back sheet 100b are overlapped by matching the outlines.

That is, the packaging bag 100 has a seal portion 101 that is adhered to each other along three of the four sides of the top sheet 100a or the back sheet 100b, and the portion along the other side is not adhered. The opening 102 for putting the printed circuit board X1 in and out is formed.

The packaging bag 100 may be composed of a sheet in which the top sheet 100a and the back sheet 100b are common to each other, or may be composed of different sheets.

The said packaging bag 100 of this embodiment is comprised by the polyolefin resin foam sheet 1 in which both the top sheet 100a and the back sheet 100b are the same.

Fig. 2 shows the cross-sectional shape of the polyolefin resin foam sheet employed as the top sheet 100a or the back sheet 100b in the present embodiment.

As shown in the drawing, the polyolefin-based resin foam sheet 1 of the present embodiment constitutes the inner surface of the packaging bag 100 and has a first surface 1a in contact with the printed circuit board X1, and the packaging bag 100 ) and a second surface 1b constituting the outer surface.

The polyolefin-type resin foam seat|seet 1 of this embodiment is comprised from the polyolefin-type resin used as a base polymer, and the polyolefin-type resin composition containing an antistatic agent.

As said polyolefin resin made to contain in the polyolefin resin foam seat|seet 1 of this embodiment, polyethylene-type resin, polypropylene-type resin, ethylene-alpha olefin resin, etc. are mentioned, for example.

It is not necessary to contain polyolefin resin individually by 1 type in the polyolefin resin composition which comprises polyolefin resin foam seat|seet, You may make it contain 2 or more types.

As polyolefin-type resin contained in a polyolefin-type resin composition, a polypropylene-type resin is preferable.

The polypropylene-based resin may be homopolypropylene (hPP), which is a homopolymer of propylene, or a copolymer containing a small amount of ethylene, butene-1, etc. in addition to propylene.

The tactility of the polypropylene-based resin is not particularly limited, and may be any of isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), atactic polypropylene (aPP), and the like.

The copolymer may be random polypropylene (rPP) in which propylene and ethylene are randomly copolymerized.

The copolymer may be block polypropylene (bPP) in which the propylene-ethylene copolymer is dispersed to constitute a domain phase in the matrix phase of homopolypropylene by introducing ethylene at a later stage of the polymerization reaction of propylene.

The block polypropylene may be an elastic in which the content of the propylene-ethylene copolymer is contained in a proportion of 40% by mass or more, or may be referred to as an olefinic thermoplastic elastomer (TPO) or the like.

The polypropylene-based resin may have long-chain branches formed by chemical crosslinking, electron beam crosslinking, or the like, or may be referred to as high melt tension polypropylene (HMS-PP) or the like.

As polypropylene resin to be contained in the polyolefin resin foam seat|seet 1, block polypropylene (bPP) and high melt tension polypropylene (HMS-PP) are preferable, and it is preferable to blend and use both.

The mass ratio (bPP/(bPP+HMS-PP)) of the block polypropylene (bPP) to the high melt tension polypropylene (HMS-PP) is preferably 20 mass% or more, more preferably 30 mass% or more, and 40 mass% % or more is particularly preferred.

It is preferable that the said mass ratio (bPP/(bPP+HMS-PP)) is 80 mass % or less, It is more preferable that it is 70 mass % or less, It is especially preferable that it is 60 mass % or less.

The high melt tension polypropylene preferably exhibits a melt tension of 3 cN or more at 230°C.

The melt tension is more preferably 4 cN or more, particularly preferably 5 cN or more.

It is preferable that it is 30 cN or less, and, as for the said melt tension, it is more preferable that it is 28 cN or less.

The melt tension can be obtained, for example, by the following method.

(Method for measuring melt tension)

When the measurement target is pellets, the sample is used as it is, and in the case of a sheet shape such as a polyolefin-based resin foam sheet, the polyolefin-based resin foam sheet is used as a pelletizer (for example, “Hand Truder Type” manufactured by Toyo Seiki Seisakusho Co., Ltd.) PM-1"), the cylinder temperature 220 degreeC, and what was pelletized under the conditions of waiting time from sample filling to the start of extrusion of 2.5 minutes is used.

The melt tension is measured using a twin bore capillary rheometer Rheologic5000T (manufactured by Cheast, Italy).

Specifically, after filling a barrel with a diameter of 15 mm heated to the test temperature, preheating for 5 minutes, and then from the capillary die (diameter 2.0 mm, length 20 mm, inflow angle flat) of the measuring device While maintaining a constant piston descending speed (0.1546 mm/s) and extruding in a strand shape, the stranded material is passed through a tension detection pulley located 27 cm below the capillary die, and then is The winding is wound while gradually increasing the winding speed at an initial speed of 8.7 mm/s and an acceleration of 12 mm/s ² , and the average of the maximum and minimum values immediately before the strand-shaped material is cut is taken as the melt tension of the sample.

On the other hand, when there is only one maximum point on the tension chart, the maximum value is taken as the melt tension.

As polyolefin-type resin preferably made to contain in a polyolefin-type resin composition, other than the above polypropylene resins, low-density polyethylene resin is mentioned.

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

As said low-density polyethylene resin (LDPE), it is preferable that the resin density is 910 kg/m<3> or more and 930 kg/m<3> or less.

As said linear low-density polyethylene resin (LLDPE), it is preferable that resin density is 910 kg/m<3> or more and 925 kg/m<3> or less.

The low-density polyethylene resin (LDPE) or the linear low-density polyethylene resin (LLDPE) preferably has a melt mass flow rate (hereinafter, also referred to as “MFR”) of 1 g/10 min or more and 10 g/10 min or less.

In the present specification, the melt mass flow rate refers to the MFR of the polymer-type antistatic agent described later, unless otherwise specified, in JIS K 7210:1999 “Plastic-thermoplastic plastic melt mass flow rate (MFR) and melt volume flow”. Test method of rate (MVR)" The value measured by the method described in method B (however, test temperature 190 degreeC, load 21.18N) is intended.

The donor-acceptor-type antistatic agent to be contained in the polyolefin-based resin composition together with the polyolefin-based resin may be, for example, a compound composed of a combination of an organoboron compound and a basic nitrogen compound.

As the said donor-acceptor type antistatic agent, it is preferable that it is excellent in compatibility with polyolefin resin, and what has an alkyl chain of a certain length is preferable.

It is preferable that the said donor-acceptor type antistatic agent is what is represented by following formula (1).

Meanwhile, in the formula (1), “R ¹ ” and “R ² ” are each independently “R ⁷ CO-OCH ₂ -” or “HOCH ₂ —”, and at least one of “R ⁷ CO-” OCH ₂ -". In Formula (1), “R ³ ” and “R ⁴ ” are each independently, “CH ₃ -”, “C ₂ H ₅ -”, “HOCH ₂ -”, “HOC ₂ H ₄ -” or “ HOCH ₂ CH(CH ₃ )-”. In the formula (1), “R ⁵ ” is “-C ₂ H ₄ -” or “-C ₃ H ₆ -”. In the formula (1), “R ⁶ ” and “R ⁷ ” are each independently alkyl having 11 to 21 carbon atoms.

Moreover, as said donor-acceptor type antistatic agent, what is shown by following formula (2) may be sufficient.

Meanwhile, in the formula (2), “R ¹ ” and “R ² ” are each independently “R ⁷ CO-OCH ₂ -” or “HOCH ₂ —”, and at least one of “R ⁷ CO-” OCH ₂ -". In Formula (2), “R ³ ” and “R ⁴ ” are each independently, “CH ₃ -”, “C ₂ H ₅ -”, “HOCH ₂ -”, “HOC ₂ H ₄ -” or “ HOCH ₂ CH(CH ₃ )-”. In the formula (2), “R ⁵ ” is “-C ₂ H ₄ -” or “-C ₃ H ₆ -”. In the formula (2), “R ⁶ ” and “R ⁷ ” are each independently alkyl having 11 to 21 carbon atoms.

In the above formulas (1) and (2), the organoboron compound portion at the upper end serves as a donor, and the basic nitrogen at the lower end serves as an acceptor.

On the other hand, "(-)" in the said donor has shown that the electron withdrawing property of a boron atom is becoming strong, and "(+)" has shown that the electron donating property of an oxygen atom is becoming strong.

In addition, "→" in the donor represents a path to which electrons are attracted, and "---" represents a state in which the bonding force between atoms is weakened.

In addition, "δ+" indicates that polarity exists in the covalent bond.

Moreover, among those represented by the above formulas (1) and (2), as the donor-acceptor-type antistatic agent in the present embodiment, an organoboron compound represented by the molecular formula "C ₄₂ H ₈₁ O ₈ B" and a molecular formula A combination of a basic nitrogen compound represented by "C ₂₃ H ₄₈ ON ₂ ", or an organoboron compound represented by a molecular formula "C ₄₂ H ₈₁ O ₈ B" and a basic nitrogen compound represented by a molecular formula "C ₂₃ H ₄₇ O ₂ N" A combination is preferred.

The content of the donor-acceptor type antistatic agent in the polyolefin-based resin composition is preferably 0.1 parts by mass or more, when the total amount of all polyolefin-based resins contained in the polyolefin-based resin composition is 100 parts by mass, and 0.2 It is more preferable that it is more than a mass part, and it is still more preferable that it is 0.3 mass part or more.

The content of the donor-acceptor type antistatic agent in the polyolefin-based resin composition is preferably 3.0 parts by mass or less, when the total amount of all polyolefin-based resins contained in the polyolefin-based resin composition is 100 parts by mass, and 2.8 It is more preferable that it is less than a mass part, and it is still more preferable that it is 2.6 mass part or less.

Since the polyolefin-based resin foam sheet 1 of the present embodiment is manufactured by the extrusion foaming method, the polyolefin-based resin composition used in the extrusion foaming method further contains, in addition to the components mentioned so far, a component necessary for foaming. can be

As a component for this foaming, a foaming agent and a bubble 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.

Especially, as said foaming agent, mixed butane of isobutane and normal butane is preferable.

In this way, when mixed butane of isobutane/normal butane is used, the rapid monoxide dispersal of the foaming agent in the extrusion process is suppressed by isobutane.

On the other hand, since normal butane excellent in compatibility with the polyolefin resin suppresses an increase in the open cell ratio, it is possible to obtain a polyolefin resin foam seat 1 having excellent cushioning properties with little shrinkage and a small open cell ratio.

On the other hand, although the quantity of the foaming agent used at the time of extrusion foaming depends also on the foaming degree requested|required, it is set as 5 mass parts or more and 25 mass parts or less normally with respect to 100 mass parts of polyolefin resin.

Usually, the addition ratio of the foaming agent falls within this range because, when the foaming agent is less than 5 parts by mass, sufficient foaming cannot be obtained, and when it exceeds 25 parts by mass, the cell membrane is destroyed and a good polyolefin-based resin foam sheet cannot be obtained.

Moreover, inorganic powders, such as a talc and a silica, etc. are mentioned as said foam|bubble control agent for adjusting the foam|bubble formed with a foaming agent. A mixture of a polyhydric carboxylic acid and sodium carbonate or sodium bicarbonate (sodium bicarbonate) used also as a decomposable foaming agent, azodicarboxylic acid amide, or the like may be used as the foam control agent.

These may be used independently or may use several things together. It is preferable that the addition amount of this foam|bubble control agent shall be 0.5 mass part or less per 100 mass parts of polyolefin resin.

In addition to the above components, you may make the polyolefin resin foam seat|seet 1 of this embodiment contain additives, such as a thermal stabilizer, a ultraviolet absorber, antioxidant, and a coloring agent, as needed.

On the other hand, it is preferable that it is 10 mass % or less, and, as for the ratio of the component contained in the polyolefin resin foam seat|seet 1 other than a polyolefin resin and a donor-acceptor type antistatic agent, it is more preferable that it is 5 mass % or less.

That is, the total ratio of the polyolefin-based resin and the donor-acceptor-type antistatic agent in the polyolefin-based resin composition constituting the polyolefin-based resin foam sheet 1 is preferably 90% by mass or more, and more preferably 95% by mass or more. Do.

It does not specifically limit about the density (apparent density) of the polyolefin resin foam seat|seet 1 comprised by the above polyolefin resin composition, It is enough to exhibit the cushioning property normally requested|required, Usually, 150 It is less than kg/m 3 , preferably 100 kg/m 3 or less, and particularly preferably 70 kg/m 3 or less.

It is preferable to select such a density because excellent flexibility and cushioning properties can be reliably imparted to the polyolefin-based resin foam sheet (1) when the density is below the upper limit, and when the density is above the lower limit, the polyolefin-based resin foam sheet (1) This is because it can exhibit excellent strength.

From this point, it is preferable that the density of the polyolefin resin foam seat|seet 1 shall be 10 kg/m<3> or more, and it is preferable to set it as 15 kg/m<3> or more.

The density of the polyolefin resin foam seat|seet 1 is measured by the method described in JISK7222:1999 "foam plastic and rubber - measurement of apparent density", specifically, it is measured by the following method.

(Density measurement method)

A sample of 100 cm 3 or more was prepared from a polyolefin-based resin foam sheet, and the sample was conditioned for 16 hours under the symbol 23/50 of JIS K7100:1999, a second-class environment, then the dimensions and mass were measured, and the apparent density was determined. It calculates by the following formula.

Apparent density (g/cm3) = mass of sample (g)/volume of sample (cm3)

In addition, the "DIGIMATIC" CD-15 type by Mitutoyo Corporation can be used for dimension measurement of a sample, for example.

It is preferable that it is 0.1 mm or more, and, as for the thickness of the said polyolefin resin foam seat|seet, it is more preferable that it is 0.15 mm or more, It is more preferable that it is 0.3 mm or more.

It is preferable that it is 6 mm or less, and, as for the thickness of the said polyolefin resin foam seat|seet, it is more preferable that it is 5 mm or less, It is more preferable that it is 4 mm or less.

The thickness of the polyolefin resin foam seat|seet 1 can be calculated|required as an average value of the thickness measured in 10 or more measurement points randomly selected, for example.

It is preferable that the basis weight of the said polyolefin resin foam seat|seet is 10 g/m<2> or more, It is more preferable that it is 15 g/m<2> or more, It is still more preferable that it is 25 g/m<2> or more.

It is preferable that the basis weight of the said polyolefin resin foam seat|seet is 600 g/m<2> or less, It is more preferable that it is 500 g/m<2> or less, It is more preferable that it is 400 g/m<2> or less.

The basis weight of the said polyolefin resin foam seat|seet can be measured by the method as described in JISP8124:2011 "paper and paperboard - basis weight measurement method."

Specifically, it can be calculated|required by the following formula by cutting out 10 samples of 100 cm<2> or more, measuring the mass and area of each.

Basis weight (g/m2) = 10000 x Test piece mass (g) / Test piece area (cm2)

It is preferable that the bleed-out amount on at least the first surface 1a (surface in contact with the object to be packaged) of the polyolefin-based resin foam sheet is 0.3 mass % or less, more preferably the bleed-out amount is 0.2 mass % or less, and the bleed-out amount is more preferably 0.2 mass % or less. It is more preferable that the amount is 0.1 mass % or less.

The bleed-out amount of the said polyolefin resin foam seat|seet can be calculated|required as follows.

The sample is cut out to a size of 100 mm x 100 mm, and the sample is put in a seal bag with a thick zipper of 120 mm x 170 mm.

20 ml of methanol is added to this seal bag, and the seal bag is shaken by hand about 100 times, evacuating as much air as possible and closing the zipper.

After shaking, the zipper is opened, the methanol in the seal bag is taken out into a beaker, and it is heated in a thermostat at 105° C. for 24 hours to evaporate the methanol to obtain a dry solid.

Thereafter, the beaker is placed in a desiccator, left to cool in the desiccator, and the mass of the evaporated product returned to room temperature is measured.

In addition, in principle, the measurement shall be performed three times using three samples cut out in each different place.

And let the average value of three measurements be the bleed-out amount of the said polyolefin resin foam seat|seet.

The polyolefin resin foam sheet preferably has an amount (total amount) of alkali metal ions and alkaline earth metal ions of at least 2 mg/m 2 on the first surface 1a (surface in contact with the object to be packaged).

The amount of alkali metal ions and alkaline earth metal ions in the first surface 1a is more preferably 1 mg/m 2 or less, and still more preferably 0.5 mg/m 2 or less.

The quantity of the alkali metal ion and alkaline-earth metal ion of the said polyolefin resin foam seat|seet can be calculated|required as follows.

The sample is cut out to a size of 100 mm x 100 mm, and the sample is put in a seal bag with a thick zipper of 120 mm x 170 mm.

20 ml of ion-exchanged water is added to this seal bag, the air is evacuated as much as possible, the zipper is closed, and the seal bag is maintained in a constant temperature bath at 60° C. After 30 minutes, the seal bag is shaken by hand 10 times.

After an additional 30 minutes, the seal bag is shaken by hand 10 times in the same manner, and then the seal bag is opened and the ion-exchanged water inside is collected. Then, the amounts of alkali metal ions and alkaline earth metal ions contained in the ion-exchanged water are measured under the following measurement conditions using a multi-type ICP emission spectroscopy apparatus (trade name "ICPE-9000", manufactured by Shimadzu Corporation). .

(Measuring conditions)

Observation direction: axial direction

Exposure time: 30 seconds

High frequency output: 1.20㎾

Carrier flow rate: 0.7 ml/min

Plasma flow rate: 10.0 ml/min

Auxiliary flow rate: 0.6 ml/min

It is preferable that the said polyolefin resin foam seat|seet shows a constant value even after the surface resistivity in the said 1st surface 1a (surface in contact with a to-be-packed object) at least performs ethanol wiping off.

Specifically, after wiping with ethanol, the surface resistivity of the polyolefin-based resin foam sheet measured under the conditions of a temperature of 20°C and a relative humidity of 60% RH is preferably 1×10 ⁸ Ω or more, and 1×10 It is more preferably ⁹ Ω or more, and more preferably 1×10 ¹⁰ 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 method for thermosetting plastics".

The surface resistivity can be measured using a test apparatus (Advantest Co., Ltd. digital ultra-high resistance/micro-current meter, model name "R3840" and resistance chamber, model name "R12702A"). The surface resistivity is calculated by the following formula by pressing the electrode under a load of about 30 N to a sample taken from the polyolefin-based resin foam sheet, measuring the resistance value after charging at 500 V for 1 minute.

In addition, let the sample be width 100mm x length 100mm x thickness (thickness in the state of a polyolefin resin foam sheet).

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

The number of samples (number of n) shall be five, and in principle, the front and back surfaces shall be measured respectively.

On the other hand, after conditioning the sample, the surface is wiped with ethanol.

Wiping with ethanol is performed as follows.

The entire measuring surface of the sample measuring 100 mm in width and height after condition adjustment is wiped several times using a paper wiper (for example, a trade name "Kimwipe") impregnated with ethanol in a small amount.

The surface resistivity is carried out after wiping and maintaining it in the test environment for 1 hour.

In addition, the surface resistivity of each sample is calculated|required by the following formula, the measured value with respect to all the samples is arithmetic average, and let the average value be the surface resistivity of polyolefin resin foam seat|seet.

ρs=(π(D+d)/(D-d))×Rs

ps: surface resistivity (MΩ)

D: inner diameter of the annular electrode on the surface (cm)

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

Rs: surface resistance (MΩ)

The polyolefin resin foam seat|seet 1 in this embodiment may contain a small amount of polymer type antistatic agent and a small amount of surfactant within the range which exhibits the above surface properties.

Examples of the polymer-type antistatic agent include ionomers such as polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, ethylene-methacrylic acid copolymer, and polyethylene glycol methacrylate copolymer. The quaternary ammonium salt, the copolymer of the olefin type block of Unexamined-Japanese-Patent No. 2001-278985, and a hydrophilic block, etc. are mentioned.

It is preferable that content of the high molecular type antistatic agent in polyolefin resin foam seat|seet shall be 1 mass % or less, It is more preferable that it is 0.5 mass % or less, It is especially preferable that it is 0.1 mass % or less.

It is especially preferable that the polyolefin resin foam seat|seet of this embodiment does not contain a polymer type antistatic agent.

As said surfactant, nonionic surfactant, anionic surfactant, cationic surfactant, amphoteric surfactant, etc. are mentioned.

It is preferable that content of surfactant in polyolefin resin foam seat|seet shall be 1 mass % or less, It is more preferable that it is 0.5 mass % or less, It is especially preferable that it is 0.1 mass % or less.

It is especially preferable that the polyolefin resin foam seat|seet of this embodiment does not contain surfactant.

In the point that the polyolefin resin foam seat|seet 1 in this embodiment can be used without discriminating front and back, it has the above surface properties not only for the said 1st surface 1a but also for the said 2nd surface 1b. It is preferable to have

However, since the second surface 1b is not in contact with the printed circuit board X1 as the object to be packaged, the packaging sheet (top sheet 100a, back sheet 100b) of the present embodiment is made of polyolefin resin foam. One side of the sheet 1 is laminated with any one of a fiber sheet (paper, fabric, etc.), a film (resin film, metal film, composite film, etc.) and a resin foam sheet that does not contain a donor acceptor type antistatic agent. A multilayer structure may be sufficient.

That is, the sheet|seat for packaging in this embodiment should just be equipped so that the polyolefin resin foam seat|seet in which the donor-acceptor type antistatic agent is mixed may be exposed on at least one surface.

In the above description, the packaging bag 100 is exemplified as a usage mode of the packaging sheet, but the packaging sheet in this embodiment can be used for other uses as well.

Another embodiment of the packaging sheet according to the present embodiment will be described with reference to FIG. 3 as an example.

The sheet for packaging shown in Fig. 3 is a single-layer sheet composed only of the polyolefin-based resin foam sheet 1, and when a plurality of glass plates 2 are laminated in the vertical direction to form a laminate 10, between adjacent glass plates 2 It is inserted into the paper and used as a paper.

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

The packaging sheet constituting the packaging bag 100 is used so that only one side (first surface 1a) of both surfaces is in contact with the printed circuit board X1 as the to-be-packed object, but the packaging sheet shown in FIG. 3 is a polyolefin-based Both the 1st surface 1a and the 2nd surface 1b of the resin foam seat|seet 1 become contact surfaces contact|abutted to the glass plate 2 which is a to-be-packed object.

Therefore, it is preferable that the sheet|seat for packaging used in this kind of embodiment is provided so that the polyolefin resin foam sheet mixed with a donor-acceptor type antistatic agent may be exposed in both surfaces.

When the polyolefin resin foam sheet is required to be exposed on both surfaces, it is not necessary for the packaging sheet to be constituted by a single polyolefin resin foam sheet 1, and two polyolefin resin foam sheets 1 are directly or , may be a laminated sheet laminated with other sheets interposed therebetween.

That is, the packaging sheet may have a two-layer structure in which the first surface layer formed on one side and the second surface layer formed on the other side are each composed of a polyolefin-based resin foam sheet containing a donor-acceptor-type antistatic agent, It has a laminated structure of three or more layers having one or two or more intermediate layers between the first surface layer and the second surface layer, and each of the first surface layer and the second surface layer contains a donor acceptor type antistatic agent. What was comprised from the polyolefin resin foam seat|seet may be sufficient.

As described above, when the sheet for packaging includes a plurality of polyolefin-based resin foam sheets, one polyolefin-based resin foam sheet and another polyolefin-based resin foam sheet share the same thickness or content of the donor-acceptor type antistatic agent, etc., or may be different. .

As mentioned above, the above polyolefin resin foam seat|seet 1 is manufactured by the extrusion foaming method in this embodiment.

Specifically, the polyolefin-based resin foam sheet 1 is manufactured by performing an extrusion process of continuously extruding and foaming the polyolefin-based resin composition into a sheet shape from a circular die mounted on the tip of the extruder to produce an extruded foam sheet. can

In the said extrusion process, since the donor-acceptor-type antistatic agent shows affinity with respect to polyolefin resin, the said donor-acceptor-type antistatic agent will be in the state contained in the polyolefin resin foam seat|seet in a favorable dispersed state.

It is known that an antistatic agent is a coating type used by applying to the surface of a resin product or the like, and a mixed type used by mixing in a resin product.

As described above, in the present embodiment, a donor-acceptor-type antistatic agent is used as a mixed-type antistatic agent.

The polyolefin-based resin foam sheet 1 in which the donor-acceptor type antistatic agent is mixed not only exhibits excellent antistatic properties, but also has little transfer of components to the mating material.

And at the said extrusion process, the bleed-out of the donor-acceptor type antistatic agent with respect to the surface of the polyolefin resin foam seat|seet 1 is suppressed.

In the extrusion process in this embodiment, the foam after primary cooling and air cooling in which the cylindrical foam continuously extruded from the circular die is air-cooled by blowing cooling air from inside and outside immediately after extrusion is further cooled with a cooling mandrel. Secondary cooling is performed.

In the said extrusion process, a cylindrical foam is taken up, cutting|disconnecting in the extrusion direction with the cutter provided on the downstream side of the mandrel for cooling.

In the said extrusion process in this embodiment, secondary cooling is performed using the mandrel for cooling which has an outer diameter larger than the diameter of a circular die.

Therefore, the said secondary cooling is performed by slidingly contacting the outer peripheral surface of the mandrel for cooling with the inner peripheral surface of the cylindrical foam which was primarily cooled.

In the said secondary cooling, the diameter expansion by the mandrel for cooling is also performed simultaneously cooling the cylindrical foam cooled primarily.

The foam cut with a cutter in the extrusion direction as described above is rolled up to constitute the original roll after it is developed into a strip shape.

In the present embodiment, in order to exhibit excellent cushioning properties to the polyolefin-based resin foam sheet 1, the high melt tension polypropylene (HMS-PP) and block polypropylene described above as polyolefin-based resins to be contained in the polyolefin-based resin composition. It is preferable to employ at least one, preferably both, of (bPP) to make the polyolefin-based resin composition low in crystallinity compared to homopolypropylene (hPP) or the like.

The heat of fusion of the ideal crystal of polypropylene is 209 J/g, and the crystallinity of homopolypropylene (hPP) is usually 50% to 70%.

It is preferable that the crystallinity degree is 40 % or less from the above points, and, as for the said polyolefin resin composition, it is more preferable that it is 30 % or less.

That is, it is preferable that it is 83 J/g or less, and, as for the amount of heat of crystallization of a polyolefin resin composition, it is more preferable that it is 62 J/g or less.

The amount of heat of crystallization of the polyolefin resin composition can be measured by the method described in JIS K7122:2012 "Method for measuring transition heat of plastics."

Specifically, it can be obtained as follows.

(How to find the amount of crystallization heat)

Using a differential scanning calorimeter device (for example, manufactured by SI Nanotechnology Co., Ltd., model name "DSC6220"), about 6 mg of the sample is filled so that there are no gaps in the bottom of the aluminum measuring vessel, and the nitrogen gas flow rate is 20 ml/min. After lowering the temperature from 30°C to -40°C, hold for 10 minutes, raise the temperature from -40°C to 220°C (1st heating), hold for 10 minutes, and then cool the temperature from 220°C to -40°C for 10 minutes After maintenance, the temperature is raised from -40°C to 220°C (2nd heating) to obtain a DSC curve.

On the other hand, all the temperature rise and fall are performed at a rate of 10° C./min, and alumina is used as the reference material.

The amount of crystallization heat is obtained from the area of the crystallization peak observed during the cooling process.

The amount of crystallization heat is calculated using the analysis software attached to the device, and the area of the part surrounded by the DSC curve and the straight line connecting the point where the DSC curve departs from the high-temperature baseline and the point where the DSC curve returns to the low-temperature baseline again can be calculated from

In this embodiment, in order to exhibit excellent cushioning properties to the polyolefin-based resin foam sheet 1, the polyolefin-based resin foam sheet is rapidly cooled to a crystallization temperature or lower by cooling with the cooling air or a cooling mandrel, and the You may make it suppress that the crystal|crystallization of polypropylene is formed.

On the other hand, the fact that crystallization of the polyolefin-based resin foam sheet 1 is suppressed means that the heat of fusion in "1st Heating" in the operation to obtain the heat of crystallization is lower than the heat of fusion obtained in "2nd Heating" can be checked

It is preferable that the ratio (Qm1/Qm2) of the heat of fusion (Qm1) in "1st Heating" with respect to the heat of fusion (Qm2) in "2nd Heating" of the polyolefin resin foam seat|seet 1 is 0.9 or less.

As for the said ratio (Qm1/Qm2), it is more preferable that it is 0.8 or less.

The heat of fusion of the polyolefin-based resin foam sheet can be obtained using the analysis software attached to the device in the same way as the heat of crystallization, and the point at which the DSC curve departs from the low-temperature side baseline, and the DSC curve returns to the high-temperature side baseline. It can be calculated from the area of the part surrounded by the straight line connecting the points and the DSC curve.

In this embodiment, the case where the said polyolefin resin foam sheet is manufactured by extrusion foaming is illustrated in the point that it is easy to prepare the polyolefin resin foam seat|seet in the state suitable as a sheet|seat for packaging as mentioned above. The polyolefin resin foam seat|seet with which the sheet|seat for packaging is equipped may be produced by another manufacturing method.

In the present embodiment, a printed circuit board or a glass plate is used as the to-be-packaged object packaged with the packaging sheet. Examples of the to-be-packaged object include a silicon wafer, a hard disk, a microprocessor, a light emitting diode, a sapphire wafer, a disk substrate, An IC chip, a magneto-optical disk (MO), a DVD, a BD, various memories, a liquid crystal filter, a magnetoresistive head for a hard disk, a CCD, a member for electrical devices, such as a reticle, and members for electronic devices are preferable.

In addition, the to-be-packaged object may be an electric device or an electronic device, such as a personal computer, a monitor, a video recorder, a smart phone, and a tablet, in which they are contained.

That is, the use in particular of the packaging sheet of this invention is not limited.

In addition, the packaging sheet of the present invention is not limited to the above-mentioned examples with respect to matters other than its use.

Example

Next, the present invention will be described in more detail by way of Examples, but the present invention is not limited thereto.

(Example 1)

As the extruder, a tandem extruder in which the first stage (upstream side) extruder was a single screw extruder having a diameter of 90 mm and the second stage (downstream side) extruder was a single screw extruder having a diameter of 115 mm was used to produce a polypropylene resin foam sheet. .

With respect to 100 parts by mass of the mixed polypropylene resin containing high melt tension polypropylene (HMS-PP) and block polypropylene (bPP) in a mass ratio of 50:50, a donor acceptor type antistatic agent (organoboron compound) and the mixture of a basic nitrogen compound) was added in the ratio used as 0.5 mass part, and the foam|bubble control agent (talc-type foam|bubble control agent) was added in the ratio used as 0.2 mass part was prepared.

This mixture is supplied to the hopper of an extruder having a diameter of 90 mm in the first stage, and after heating and melting at 200 ° C., butane (isobutane / normal butane = 35) as a foaming agent so that the ratio to 100 parts by mass of this molten resin is 4 parts by mass. /65) was press-fitted from the middle of the first stage extruder, and melt-kneaded by the extruder.

The kneaded material obtained by melt-kneading was supplied to the second-stage extruder through a connecting pipe, and the temperature of the kneaded material was lowered to 170°C while continuing to knead the kneaded material inside the extruder.

In this way, the temperature-reduced kneaded material is extruded into a cylindrical shape in the air from the circular slit of a circular die connected to the tip of the extruder with a diameter of 140 mm and a slit gap of 0.95 mm connected to the tip of the extruder so that the extrusion amount is 98.5 kg/hour, and the kneaded material is extruded into the air. was foamed to form a cylindrical foam.

While expanding and taking out the foam with a cooled mandrel (mandrel diameter: φ414 mm, length: 500 mm), an air ring is used to blow air on the outer surface of the foam to cool the foam, and a cutter is used to cool the foam. One foam was cut to prepare a polyolefin-based resin foam sheet.

(Example 2)

Same as Example 1, except that low-density polyethylene (LDPE) was used instead of the mixed polypropylene resin, the amount of the donor acceptor type antistatic agent was changed from 0.5 parts by mass to 0.3 parts by mass, and the extrusion conditions were changed. A polyolefin-based resin foam sheet was produced.

(Example 3)

Polyolefin resin foam seat|seet was produced similarly to Example 2 except having changed the quantity of the donor-acceptor type antistatic agent from 0.3 mass part to 2.0 mass parts.

(Comparative Example 1)

Polyolefin-based resin foaming in the same manner as in Example 1, except that a polymer-type antistatic agent was used instead of the donor-acceptor-type antistatic agent, and the amount of the polymer-type antistatic agent added to 100 parts by mass of the mixed polypropylene-based resin was 8 parts by mass. sheet was made.

(Comparative Example 2)

A polyolefin-based polyolefin-based agent was used in the same manner as in Example 2, except that a surfactant (stearic acid monoglyceride) was used instead of the donor-acceptor type antistatic agent, and the amount of the surfactant was 1.5 parts by mass with respect to 100 parts by mass of low density polyethylene (LDPE). A resin foam sheet was produced.

(Comparative Example 3)

Polyolefin in the same manner as in Comparative Example 2, except that the surfactant was changed from monoglyceride stearate to alkyldiethanolamide, and the amount of the surfactant was changed from 1.5 parts by mass to 3.4 parts by mass with respect to 100 parts by mass of low-density polyethylene (LDPE). A system resin foam sheet was produced.

The physical properties of the obtained polyolefin resin foam seat|seet are as a table|surface.

(Physical property evaluation item)

Thickness: thickness of polyolefin resin foam sheet

Basis weight: basis weight of polyolefin resin foam sheet

Surface resistivity: After wiping the surface of the polyolefin resin foam sheet with ethanol, the surface resistivity measured under the conditions of a temperature of 20 degreeC and a relative humidity of 60%RH.

Bleed-out amount: Bleed-out amount on the surface of polyolefin-based resin foam sheet

Metal ion amount: Total amount of alkali metal ion and alkaline earth metal ion in the surface of polyolefin resin foam seat|seet

From the above results, it can be seen that providing the sheet for packaging with the polyolefin-based resin foam sheet containing the donor-acceptor type antistatic agent effectively reduces the migration of components to the object to be packaged.

That is, from the above points, it can be seen that the sheet for packaging of the present invention has less transfer of components to the object to be packaged and has excellent antistatic properties.

1: Polyolefin resin foam sheet
1a: first side
1b: second side
2: glass plate
10: laminate
11, 12: coating film
100: packaging bag
100a: surface sheet
100b: back sheet
101: seal part
102: opening
X1: printed circuit board

Claims (3)

A polyolefin-based resin foam seat comprising a polyolefin-based resin composition comprising a polyolefin-based resin and a donor acceptor-type antistatic agent,
The polyolefin-based resin is a mixed polypropylene-based resin of high melt tension polypropylene (HMS-PP) and block polypropylene (bPP),
The melt tension of the high melt tension polypropylene (HMS-PP) is 3cN or more and 30cN or less at 230°C,
The mass ratio (bPP/(bPP+HMS-PP)) of the block polypropylene (bPP) to the high melt tension polypropylene (HMS-PP) is 30 mass % or more and 80 mass % or less,
The polyolefin-based resin composition has a crystallinity of 40% or less,
A packaging sheet provided such that the polyolefin-based resin foam sheet is exposed on at least one surface. The method of claim 1,
The content of the antistatic agent contained in the polyolefin-based resin composition is 0.1 parts or more and 3 parts or less with respect to 100 parts by mass of the polyolefin-based resin contained in the polyolefin-based resin composition. 3. The method according to claim 1 or 2,
The thickness of the polyolefin-based resin foam sheet is 0.15 mm or more and 5 mm or less, and the basis weight is 15 g/m 2 or more and 500 g/m 2 or less,
The said surface of the said polyolefin resin foam seat|seet is
The bleed-out amount is 0.2 mass % or less,
The amount of alkali metal ions and alkaline earth metal ions is 1 mg/m 2 or less, and
A packaging sheet having a surface resistivity of 1×10 ⁹ Ω or more and 1×10 ¹² Ω or less after wiping with ethanol, measured at a temperature of 20° C. and a relative humidity of 60% RH.

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