JP2014136755A - Polyethylene-based resin foamed sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene-based resin foamed sheet capable of easily removing foreign matter adhered to a glass by washing with water.SOLUTION: There is provided a polyethylene-based resin foamed sheet which contains a polyethylene-based resin, a polymer-type antistatic agent, an anionic surfactant and a nonionic surfactant, wherein the polyethylene-based resin foamed sheet contains 5 to 15 pts.mass of the polymer-type antistatic agent, 0.1 to 5 pts.mass of the anionic surfactant and 0.1 to 0.5 pts.mass of the nonionic surfactant based on 100 pts.mass of the polyethylene-based resin, and the mass ratio of the anionic surfactant to the nonionic surfactant is 1 to 10.

Description

  The present invention relates to a polyethylene resin foam sheet.

Polyethylene resin foam sheets (hereinafter also referred to as “foam sheets”) are flexible and have excellent cushioning properties, and are therefore used in packaging materials for electronic parts and home appliances, glass slip sheets, and the like.
For example, glass substrates for flat panel displays such as liquid crystal displays and plasma displays are laminated with a polyolefin resin foam sheet interposed therebetween and supplied from a glass manufacturer to a display manufacturer.
In addition, since this kind of glass substrate has a possibility of causing various troubles in the flat panel display when foreign matter adheres to the surface, it is used after a step of washing with water once. .

  For this reason, the foamed sheet is required to be easily removed by water washing even if foreign matter such as dust adheres to the surface of the glass substrate.

  In response to such a demand, for example, a foam sheet containing a polyalkylene oxide surfactant which is a nonionic surfactant has been proposed (for example, Patent Document 1).

JP 2009-185210 A

  Since such a foam sheet contains a nonionic surfactant, even if foreign matter adheres to the surface of the glass substrate, the foreign matter can be washed out together with the nonionic surfactant by washing the surface of the glass substrate with water. Have advantages.

By the way, recently, since the glass substrate is used in more precise equipment and the like, it is required to further remove foreign substances adhering to the surface of the glass substrate.
In response to this demand, it is conceivable to increase the amount of nonionic surfactant in order to further enhance the effect of removing foreign substances.
However, even if the amount of the nonionic surfactant is increased, the cleaning effect is not sufficient. On the other hand, the nonionic surfactant itself adheres to the surface of the glass substrate as a large amount of foreign matter, and the surface of the glass substrate is washed with water. Even so, there is a problem that the nonionic surfactant remains on the surface of the glass substrate.

  This invention makes it a subject to provide the polyethylene-type resin foam sheet which the removal by the water washing of the foreign material adhering to glass is easy in view of the said request point.

  As a result of intensive studies by the present inventors, it was found that the foreign matter adhering to the glass is composed of a stearic acid compound having a relatively high lipophilicity, and other sebum, fibers, resin fine particles and the like. . Further, it has been found that, by using an anionic surfactant and a nonionic surfactant in combination with such a foreign substance, the foreign substance attached to the glass can be easily removed by washing with water. And by discovering these, the present invention has been conceived.

  That is, the present invention includes a polyethylene-based resin, a polymer-type antistatic agent, an anionic surfactant, and a nonionic surfactant, and the polymer-type charge is added to 100 parts by mass of the polyethylene-based resin. 5 to 15 parts by mass of an inhibitor, 0.1 to 5 parts by mass of the anionic surfactant, 0.1 to 0.5 parts by mass of the nonionic surfactant, and relative to the nonionic surfactant The polyethylene resin foam sheet is characterized in that a mass ratio of the anionic surfactant is 1 to 10.

  According to such a polyethylene-based resin foam sheet, by containing an anionic surfactant and a nonionic surfactant, it is easy to remove foreign matters attached to the glass by washing with water. Nonionic surfactants are particularly effective for stearic acid compounds with a relatively high lipophilicity, and anionic surfactants are especially effective for other sebum, fibers, resin particles, etc. It is thought that it is effective.

  ADVANTAGE OF THE INVENTION According to this invention, the polyethylene-type resin foam sheet which can remove easily by water washing of the foreign material adhering to glass can be provided.

The polyethylene resin foam sheet of this embodiment is a polyethylene resin foam sheet containing a polyethylene resin, a polymer antistatic agent, an anionic surfactant, and a nonionic surfactant (hereinafter simply referred to as “foam sheet”). Is also called.).
About the foamed sheet, a foam formed by extrusion foaming a polyethylene resin composition containing a polymeric antistatic agent, an anionic surfactant, and a nonionic surfactant together with a polyethylene resin. The embodiment will be described while illustrating a sheet.

  First, the material which comprises the foam sheet of this embodiment is demonstrated.

The polyethylene resin constituting the foamed sheet of the present embodiment has a melt mass flow rate (hereinafter also referred to as “MFR”) of 2 to 6 g / 10 min and a resin density of 925 kg / m ³ or more and 935 kg / m ³ or less. It is preferable to use a low density polyethylene resin.
The MFR low density polyethylene resin as described above is preferable because if the MFR is excessively small, a problem arises in kneadability with the polymer antistatic agent in the extruder and the antistatic performance is lowered. This is because it may be difficult to obtain a good foamed sheet by causing foam breakage.
Also, the MFR low density polyethylene resin as described above is preferable because if the MFR is excessively large, the melt tension becomes too low and it becomes difficult to obtain a low density foam sheet. This is because it tends to occur.
That is, it is preferable to use a low-density polyethylene resin having an MFR of 2 g / 10 min or more and 6 g / 10 min or less, not only because it is easy to make the resulting foamed sheet into a good foamed state, This is because the production efficiency of the foamed sheet can be improved by reducing the effort for removing the deposit.

  In the present specification, the melt mass flow rate of JIS K 7210: 1999 “Plastic-thermoplastic melt mass flow” is also used for the MFR of the polymer type antistatic agent described below, unless otherwise specified. This is intended to be a value measured by the method described in Method B (however, the test temperature is 190 ° C. and the load is 21.18 N). (Test method for rate (MFR) and melt volume flow rate (MVR))

The polyethylene-based resin constituting the foamed sheet of the present embodiment preferably has the above-described density. If the resin density is excessively small, the foaming agent is not removed from the foamed sheet after extrusion. This is because the dispersion is fast and the rigidity of the resin itself may be reduced, so that shrinkage may not be suppressed.
In addition, it is preferable that the polyethylene-based resin has the density as described above. If a resin density having an excessively large value is adopted, the rigidity of the resin itself is too large, and the foam sheet is a packaging material. This is because there is a risk of losing cushioning properties.
That is, the reason why the polyethylene resin constituting the foamed sheet of the present embodiment preferably has the above density is that it is advantageous for forming a foamed sheet having excellent cushioning properties.

As the polymer antistatic agent constituting the foamed sheet together with the polyethylene resin, a polymer antistatic agent having a crystallization temperature of less than 90 ° C. and an MFR of 10 to 40 g / 10 min is preferable.
The crystallization temperature of the polymer type antistatic agent is preferably less than 90 ° C. If the crystallization temperature is excessively high, the crystallization proceeds in the extruder, resulting in poor dispersion, and extrusion foaming. Sometimes when the cell membrane is stretched, the polymer antistatic agent does not deform and becomes a lump, and the distance between dispersed particles of the antistatic agent becomes wide, making it difficult to develop an antistatic function commensurate with the amount added. is there.
That is, the reason why the crystallization temperature of the polymer antistatic agent is preferably less than 90 ° C. is because it is advantageous in causing the foam sheet to exhibit an antistatic function commensurate with the amount of addition.

In addition, the MFR of the polymer antistatic agent is preferably within the above-described range. If the MFR of the polymer antistatic agent is excessively small, the polyethylene resin in the extruder or in the die is used. This is because the dispersion is uneven and the surface resistivity is excellent, but the static electricity decay rate tends to deteriorate.
In addition, it is preferable that the MFR is in the above-described range. When a polymer type antistatic agent having an excessively high MFR is used, the dispersibility in the polyethylene resin is lowered and the polyethylene resin composition is reduced. This is because the melt tension is lowered, so that a low-density foam sheet cannot be obtained, or there is a possibility of generating coarse bubbles that are communicated.
That is, the MFR of the polymer type antistatic agent is preferably in the above range because it is advantageous for exhibiting an excellent electrostatic decay rate in a foamed sheet having a good foamed state.

In the present specification, the crystallization temperature is intended to be a value measured according to the method described in JIS K7122: 1987 “Method for measuring plastic transition temperature” unless otherwise specified.
Specifically, using a differential scanning calorimeter (for example, “DSC6220” manufactured by S.I. Nano Technology Co., Ltd.), about 6.5 mg of a sample is filled in a measurement container, and a nitrogen gas flow rate is set to 30 ml / min. The temperature is raised from 30 ° C. to 200 ° C. at a rate of 10 ° C./min and then cooled at a cooling rate of 10 ° C./min, and the exothermic peak temperature at the time of cooling can be measured as the crystallization temperature.
In addition, when two or more exothermic peaks appear, the temperature of the peak of the highest temperature peak among the area peaks having 5% or more of the total peak area is defined as the crystallization temperature.

  Examples of the polymer antistatic agent include polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, ionomers such as ethylene-methacrylic acid copolymer, and quaternary such as polyethylene glycol methacrylate copolymer. Examples thereof include ammonium salts and copolymers of olefinic blocks and hydrophilic blocks described in JP-A No. 2001-278985.

Among these, a copolymer of an olefin block and a hydrophilic block is preferable, and a polyether-polyolefin block copolymer (a block copolymer of a polyether block and a polyolefin block) is charged with the above-described polymer type charging. It is preferable to make it contain in a polyethylene-type resin composition as an inhibitor.
The polymer type antistatic agent may be a mixture of two or more substances. For the purpose of further improving the antistatic performance, the block copolymer is mixed with polyamide, or a polyamide-based antistatic agent. The block may be further copolymerized.

As the polymer type antistatic agent, those having as a main component a copolymer of an olefin block and a polyether block containing 70 mol% or more of propylene are more preferable.
Here, the phrase “the main component” of the copolymer means that the proportion of the polyether-polyolefin block copolymer in the polymer antistatic agent is 50% by mass or more.
In addition, it is preferable that the ratio for which the said polyether-polyolefin block copolymer accounts to a polymer type antistatic agent shall be 70 mass% or more, and it is more preferable to set it as 80 mass% or more.

In the polyethylene resin composition constituting the polyethylene resin foam sheet of the present embodiment, the blending ratio of the polyethylene resin and the polymer-type antistatic agent is as described above with respect to 100 parts by mass of the polyethylene resin. It is important that the molecular antistatic agent has a ratio of 5 to 15 parts by mass.
It is important that the blending ratio of the polymer type antistatic agent in the polyethylene resin composition is within the above range. By setting the blending ratio to be equal to or higher than the lower limit of the above range, the antistatic performance of the foam sheet is insufficient and the glass substrate is used. This is because dust can be prevented from adhering and, for example, peeling electrification when peeling from the glass substrate can be suppressed.
In addition, it is preferable that the blending ratio of the polymer type antistatic agent in the polyethylene resin composition is within the above range, because not only the upper limit value of the above range but also the cost increase of the foam sheet can be suppressed. It is because it can prevent that the foamability of a polyethylene-type resin composition falls and a low-density foam sheet cannot be obtained.

The anionic surfactant to be contained in the polyethylene resin foam sheet functions as an antistatic agent as a so-called low molecular weight antistatic agent. In the present embodiment, the anionic surfactant that is solid at 20 ° C. Among them, it is more preferable to employ an anionic surfactant having an HLB value of 20 or more (the upper limit is usually 50) by the Davis method.
The Davis method is a method in which a surfactant molecule is divided into atomic groups (or functional groups), a specific number of groups is given to each atomic group, and an HLB value is obtained by calculation. For example, Sanyo Chemical Industries, Ltd. It can be calculated based on the method specifically described in the book name “Introduction to Surfactant” issued by the company.
In the following description, “HLB value” means “HLB value by Davis method” unless otherwise specified.

Examples of the anionic surfactant include dialkyl sulfosuccinate, alkyl sulfonate, alpha olefin sulfonate, linear alkyl benzene sulfonate, naphthalene sulfonate-formaldehyde condensate, alkyl naphthalene sulfonate, N -Sulfonate surfactants such as methyl-N-acyl taurine salts; Carboxylic acids such as aliphatic monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acyl sarcosinates, N-acyl glutamates Salt-based surfactants; sulfate ester-based surfactants such as alkyl sulfates, polyoxyethylene alkyl ether sulfates, and oil sulfates; alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene Alkylphenyl ester It can be employed as phosphate salt-based surfactants such as telluric acid salt.
In addition, said anionic surfactant does not need to be used individually by 1 type, and may mix and use 2 or more types.

If the content of the anionic surfactant in the foam sheet is too small, it is difficult to expect an effect of preventing substances other than the anionic surfactant from adhering to the surface of the glass substrate. At the same time, it becomes difficult to impart a sufficient antistatic effect to the foam sheet.
On the other hand, since there is a limit to the improvement of the antistatic effect and the suppression effect of deposits other than the anionic surfactant, even if the anionic surfactant is contained in the foam sheet more than necessary, the foam sheet is simply There is a risk of making it difficult to manufacture.
For this reason, it is important that the anionic surfactant is contained in the foam sheet so that the ratio to 100 parts by mass of the polyethylene resin is 0.1 to 5 parts by mass. It is preferable to contain in a foam sheet so that it may become a mass part.

Among those exemplified above, as the anionic surfactant to be contained in the foamed sheet in the present embodiment, it is preferable to employ a solid one at 20 ° C. in that it can be easily washed and removed from the glass substrate surface. Among them, a sulfonate surfactant that is solid at 20 ° C. is more preferable.
As the sulfonate surfactant, an alkyl sulfonate is preferably used.
Among them, the alkyl sulfonate is particularly preferably a sodium alkyl sulfonate surfactant.

  As the nonionic surfactant to be contained in the polyethylene resin foam sheet, a polyoxyalkylene surfactant or the like can be employed.

When the content of the nonionic surfactant in the foamed sheet is too small, it is difficult to expect an effect of preventing substances other than the nonionic surfactant from adhering to the surface of the glass substrate. .
On the other hand, since there is a limit to the improvement of the inhibitory effect of deposits other than nonionic surfactants, the nonionic surfactant is made of glass even if the nonionic surfactant is contained in the foam sheet more than necessary. There is a risk of adhering to the surface of the substrate.
For this reason, it is important that the nonionic surfactant is contained in the foam sheet so that the ratio to 100 parts by mass of the polyethylene resin is 0.1 to 0.5 parts by mass. It is preferable to make it contain in a foam sheet so that it may become -0.4 mass part.

  Among those exemplified above, a polyoxyalkylene surfactant is preferably employed as the nonionic surfactant contained in the foamed sheet in the present embodiment in that it can exhibit an excellent cleaning effect.

When the mass ratio of the anionic surfactant to the nonionic surfactant is too small, the nonionic surfactant remains on the glass, and the cleaning effect may be insufficient.
On the other hand, when the mass ratio of the anionic surfactant to the nonionic surfactant is excessive, the cleaning effect of the organic metal salt such as the stearic acid compound may be insufficient.
Therefore, it is important that the mass ratio of the anionic surfactant to the nonionic surfactant is 1 to 10, and preferably 1 to 8.

The nonionic surfactant preferably has a softening point lower than the softening point of the anionic surfactant. In the foam sheet, the nonionic surfactant bleeds before the anionic surfactant because the softening point of the nonionic surfactant is lower than the softening point of the anionic surfactant. Therefore, the nonionic surfactant can be effectively brought into contact with a stearic acid compound having a relatively high lipophilicity, and a cleaning effect on the stearic acid compound having a relatively high lipophilicity is exhibited.
In addition, a softening point can be calculated | required by the measurement based on JISK5601-2-2: 1999. Specifically, it is measured by a ring and ball method using distilled water as a heating medium.

In addition, since the polyethylene-type resin foam sheet of this embodiment is manufactured by extrusion foaming, in addition to the component described so far, the component required for foaming is further contained.
Examples of the foaming component include a foaming agent and a bubble regulator. In addition to these, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant, and a colorant may be added as necessary. It can also be contained in a foam sheet.

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, the mixed butane of isobutane and normal butane is preferable.

  When isobutane / normal butane mixed butane is used in this manner, isobutane suppresses rapid dissipation of the foaming agent in the extrusion foaming process, while normal butane having excellent compatibility with the polyethylene-based resin is open-celled. Since the increase in the rate is suppressed, it is possible to obtain a foam sheet that is excellent in cushioning properties with little shrinkage and low open cell rate.

The amount of the foaming agent used for extrusion foaming depends on the desired degree of foaming, but is usually 5 parts by mass or more and 25 parts by mass with respect to a total of 100 parts by mass of the polyethylene resin and the polymer antistatic agent. It is as follows.
Usually, the addition ratio of the foaming agent is within such a range that if the foaming agent is 5 parts by mass or more, sufficient foaming is easily obtained. This is because it is possible to suppress tearing of the film.

In addition, as the bubble adjusting agent for adjusting bubbles formed by the foaming agent, polyvalent carboxylic acid and sodium carbonate or sodium bicarbonate (sodium bicarbonate) used as inorganic powders such as talc and silica, or as a decomposable foaming agent And azodicarboxylic acid amide.
These may be used alone or in combination. It is preferable that the addition amount of this bubble regulator shall be 0.5 mass part or less per 100 mass parts of polyethylene-type resin.

  The foamed sheet according to the present embodiment can be produced in the same manner as a general extruded foamed sheet. For example, an extruded foaming process for producing an extruded foamed sheet by extrusion foaming the polyethylene resin composition. Winding process of winding the extruded sheet with a winder to produce a raw roll, aging process for aging the wound raw roll for a certain period, and winding the raw roll on a product roll with a rewinder It can be manufactured by performing a makeup winding process.

The thickness of the foamed sheet is preferably 0.3 to 2 mm, more preferably 0.3 to 1 mm. The said foam sheet has the advantage that it becomes what was excellent in shock-absorbing property because thickness is 0.3 mm or more. Moreover, when the said foam sheet is 2 mm or less in thickness, when it uses as a slip sheet of a glass substrate, it has the advantage that stacking efficiency improves.
As for the thickness of the foamed sheet, a constant pressure thickness measuring machine (manufactured by Teclock, model “SCM-627”) was used, and a circular surface (area: 60.8 cm ² ) having a radius of 4.4 cm using a cylindrical weight. ), The thickness of the foam sheet when a load of 95 g (including its own weight) is applied to the foam sheet can be measured.
In addition, 50 points are measured every 5 cm in the width direction, and the arithmetic average value of the measured values is defined as the thickness. Moreover, when the measurement location for 50 points | pieces cannot be obtained, it measures as much as possible and makes arithmetic mean value of the measured value thickness.

The basis weight of the foam sheet is preferably 15 to 50 g / m ^2, more preferably a 20 to 40 g / m ^2. The foam sheet has an advantage that the waist strength is high when the basis weight is 15 g / m ² or more. Moreover, the said foaming sheet has the advantage that it becomes what was excellent in shock absorbing property because basic weight is 50 g / m < ² > or less.
The basis weight of the foam sheet is obtained by cutting the foam sheet in a direction of 20 cm in the extruding direction in the direction orthogonal to the extruding direction, and obtaining the mass W (g) and the area S (cm ² ) of the section by the following formula. In addition, when it is not large enough to be cut in the direction orthogonal to the extrusion direction with a width of 20 cm, it is cut out on a rectangle to a possible size, and from the mass W (g) and area S (cm ² ) of the section. Obtained by the following formula.
Basis weight (g / m ² ) = W / S × 10000

The surface resistivity of the foamed sheet is preferably 10 ⁶ to 10 ¹² Ω / □, more preferably 10 ⁸ to 10 ¹² Ω / □. The foamed sheet has an advantage that it can sufficiently suppress bleed-out of low molecular weight components due to the polymer antistatic agent when the surface resistivity is 10 ⁶ Ω / □ or more. In addition, the foam sheet has a surface resistivity of 10 ¹² Ω / □ or less, so that static electricity can be suppressed during the production of the foam sheet or when the foam sheet is used. It has the advantage that it can suppress adhering to.
The specific surface resistivity of the foamed sheet is measured by the method described in JLS K6911: 1995 “General Test Method for Thermosetting Plastics”.

  Next, the present invention will be described more specifically with reference to examples and comparative examples.

(Evaluation)
The example which performed various evaluation about the foam sheet 7 days after the foaming by extrusion is shown.
First, physical properties of the material, physical properties of the foam sheet, and evaluation methods for the foam sheet will be described.

(Softening point of surfactant)
It was measured by the method described above.

(Thickness and basis weight of foam sheet)
It was measured by the method described above.

(Surface specific resistivity of foam sheet)
The surface resistivity of the foamed sheet was measured by the method described in JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. That is, using a test device (Advantest Co., Ltd. digital super high resistance / microammeter R8340 and resiliency chamber R12702A), an electrode is pressure-bonded to the test piece with a load of about 30 N and charged at 500 V for 1 minute. The surface resistivity was calculated from the following equation.
In addition, the test piece cut out the thing of width 100mm x length 100mm x original fabric thickness from the original fabric of the foam sheet, and produced it. Further, after placing the test piece for 24 hours or more in an atmosphere with a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%, the above measurement was performed as a test environment in an atmosphere of a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%. . The number of test pieces was five, both the front and back surfaces of each test piece were measured, and the arithmetic average value of a total of ten measurement values was defined as the surface resistivity.
ρs = π (D + d) / (D−d) × Rs
ρs: surface resistivity (Ω / □)
D: Inner diameter (cm) of the annular electrode on the surface (7 cm for the resistance chamber R12702A)
d: outer diameter (cm) of inner circle of surface electrode (5 cm for resiliency chamber R12702A)
Rs: Surface resistance (Ω)

(Contact angle of glass plate)
The suitability of the glass substrate as a slip sheet was determined by the contact angle as follows.
First, the foam sheet is cut into a size of 5 cm × 10 cm, and this is placed on a cleaned and dried glass plate (Non-alkali glass OA-10G manufactured by Nippon Electric Glass Co., Ltd.), and further, the entire foam sheet is loaded. Add a 1 kg weight to add, and let stand in a constant temperature and humidity chamber (trade name “HPAV-120-40”, manufactured by ISUZU Seisakusho) with a temperature of 60 ° C. and a relative humidity of 80% for 24 hours. Dried for 24 hours at 0% relative humidity. The glass plate subjected to this treatment is washed with washing water containing 0.4% by mass of household alkaline detergent (trade name “Attack” manufactured by Kao Corporation), rinsed with distilled water, and then subjected to temperature treatment. It was dried for 24 hours at 30 ° C. and 0% relative humidity.
The contact angle of purified water on the surface of the glass plate that was in contact with the foamed sheet was measured with a solid-liquid interface analyzer (trade name “DROP MASTER300”) manufactured by Kyowa Interface Chemical Co., Ltd., and the contact angle after cleaning was determined.
In addition, the contact angle after washing | cleaning measured 20 points, respectively, and computed it with the average value.

(Amount of stearic acid compound attached)
The surface of the glass after measuring the contact angle after washing is observed with a microscope, and IR microscopic IR measurement is performed on all substances adhering to 2 cm × 2 cm of each glass, and the stearic acid compound is added. The number of aggregates contained was measured, and the arithmetic average value was determined from the measured values (n = 3).
The measuring method is as follows.
For the measurement, a Fourier transform infrared spectrophotometer Spectrum One (manufactured by Perkin Elmer) and a high-speed IR imaging system Spectrum Spotlight 300 were used.
Measurement mode: spot / ATR method <measurement conditions>
Resolution: 4cm ^-1
Number of scans: 256 times aperture: 100 × 100 μm
As a pretreatment method, dirt was transferred to an ATR crystal and measured by the ATR method.

(Cleanability of glass)
The detergency of the glass was evaluated from the results of “contact angle after cleaning” and “adhesion amount of stearic acid compound”.
○: When the contact angle after washing is 10 ° or less and the amount of stearic acid compound attached is 1/4 cm ² or less.

Example 1
Low-density polyethylene resin manufactured by Nippon Polyethylene Co., Ltd. (trade name: “LF580”, density: 929 kg / m ³ , MFR = 4.0 g / 10 min), 100 parts by mass, polymer type charging manufactured by Sanyo Chemical Co., Ltd. 6 parts by mass of an inhibitor (polyether-polypropylene block copolymer, trade name: “Pelestat 300”, crystallization temperature: 85.4 ° C., MFR = 30 g / 10 min), trade name “Chemistat” manufactured by Sanyo Chemical Co., Ltd. 3033 "(containing 90% by mass or more of sodium alkyl sulfonate having 12 to 16 carbon atoms as an anionic surfactant. Softening point 70 ° C) and 0.5 part by mass, and a cell regulator made by Sankyo Kasei Co., Ltd. A master batch (azodicarbonamide-containing master batch: trade name “Cermic MB1023”) was blended at a ratio of 0.3 part by mass. Compound tandem extruder first extruder (cylinder diameter: 90 mm) was supplied to the maximum reachable temperature at the extrusion machine was melt-kneaded such that the 210 ° C.. The softening point of “sodium alkyl sulfonate having 12 to 16 carbon atoms” is the same as the softening point of “chemistat 3033”.
Further, mixed butane (isobutane / normal butane = 50/50 (molar ratio)) as a foaming agent was pressed in from the middle of the first extruder so that the ratio with respect to 100 parts by mass of the low-density polyethylene resin was 15 parts by mass. Further, a ratio of polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., trade name: “PEG600”) as a nonionic surfactant in the middle of the first extruder is 0.4 parts by mass with respect to 100 parts by mass of the low-density polyethylene resin. The melt kneading was carried out by press-fitting so that
After melt-kneading in this first extruder, it is cooled to a temperature range (111 ° C.) suitable for foaming with a second extruder (cylinder diameter: φ150 mm) connected to the first extruder, and the outlet diameter is 222 mm ( It was extruded and foamed into the atmosphere from a circular die having a slit of 0.04 mm. The resin temperature at that time was 114 ° C.
The extruded foam is cooled by blowing air and then cooled along a cooling mandrel having a diameter of 770 mm and a length of 650 mm. A cylindrical foam was cut along the line to obtain a long band-shaped foam sheet, which was wound at a winding speed of 35 m / min to form a foam sheet.

(Example 2)
The amount of the trade name “Chemist 3033” manufactured by Sanyo Chemical Co., Ltd. was changed to 0.8 parts by mass with respect to 100 parts by mass of the low-density polyethylene resin. Polyethylene glycol having a different softening point as a nonionic surfactant (Sanyo Kasei) Example, except that Co., Ltd., trade name: “PEG1000”) was used, and the amount of the nonionic surfactant was changed to 0.1 parts by mass with respect to 100 parts by mass of the low-density polyethylene resin. In the same manner as in Example 1, a roll-shaped foam sheet was obtained.

(Example 3)
Polyoxyethylene lauryl ether (trade name: “Emulgen 109P” manufactured by Kao Corporation) was used as a nonionic surfactant in place of polyethylene glycol, and the amount of nonionic surfactant was changed to low density polyethylene resin 100. A roll-shaped foam sheet was obtained in the same manner as in Example 1 except that the content was changed to 0.2 parts by mass with respect to mass parts.

(Comparative Example 1)
Example 1 and Example 1 except that an anionic surfactant was not used and polyethylene glycol having a different softening point (trade name: “PEG1000”, manufactured by Sanyo Chemical Co., Ltd.) was used as a nonionic surfactant. Similarly, a roll-shaped foam sheet was obtained.

(Comparative Example 2)
Polyethylene glycol having a different softening point was used as the nonionic surfactant (trade name: “PEG1000” manufactured by Sanyo Chemical Co., Ltd.), and the amount of the nonionic surfactant was 100 parts by mass of the low-density polyethylene resin. A roll-shaped foam sheet was obtained in the same manner as in Example 1 except that the content was changed to 2.0 parts by mass.

(Comparative Example 3)
Polyethylene glycol having a different softening point was used as the nonionic surfactant (trade name: “PEG1000” manufactured by Sanyo Chemical Co., Ltd.), and the amount of the nonionic surfactant was 100 parts by mass of the low-density polyethylene resin. A roll-shaped foam sheet was obtained in the same manner as in Example 1 except that the content was changed to 0.02 parts by mass.

  The test results are shown in Table 1.

As shown in Table 1, the foam sheets of Examples 1 to 3 within the scope of the present invention are the foam sheet of Comparative Example 1 that does not contain an anionic surfactant, and 100 parts by mass of polyethylene resin. In contrast to the foamed sheet of Comparative Example 3 in which the amount of the nonionic surfactant is less than 0.1 parts by mass and the mass ratio of the anionic surfactant to the nonionic surfactant exceeds 10. There was little adhesion amount of the stearic acid type compound on the glass after washing | cleaning. From this, it can be seen that the foamed sheets of Examples 1 to 3 are less likely to have stearic acid compounds having a relatively high lipophilicity remaining on the glass surface as compared with the foamed sheets of Comparative Examples 1 and 3.
Moreover, as shown in Table 1, the foamed sheets of Examples 1 to 3 within the scope of the present invention are the foamed sheet of Comparative Example 1 that does not contain an anionic surfactant, and 100 mass of polyethylene resin. Compared to the foamed sheet of Comparative Example 2 in which the amount of nonionic surfactant exceeds 0.5 parts by mass with respect to parts and the mass ratio of the anionic surfactant to the nonionic surfactant is less than 1. The contact angle after washing was low. From this, it can be seen that the foam sheets of Examples 1 to 3 are less likely to retain sebum, fibers, resin fine particles and the like on the glass surface than the foam sheets of Comparative Examples 1 and 2.
Therefore, according to this invention, compared with the past, the polyethylene-type resin foam sheet which can remove easily the foreign material adhering to glass by water washing can be provided.

Claims (4)

Contains a polyethylene resin, a polymer antistatic agent, an anionic surfactant, and a nonionic surfactant,
5 to 15 parts by mass of the polymeric antistatic agent, 0.1 to 5 parts by mass of the anionic surfactant, and 0.1 to 0.1 parts of the nonionic surfactant with respect to 100 parts by mass of the polyethylene resin. Containing 0.5 parts by mass,
The polyethylene-based resin foam sheet, wherein a mass ratio of the anionic surfactant to the nonionic surfactant is 1 to 10.   The polyethylene resin foam sheet according to claim 1, wherein the anionic surfactant is an alkyl sulfonate surfactant, and the nonionic surfactant is a polyoxyalkylene surfactant.   The polyethylene-based resin foamed sheet according to claim 1 or 2, wherein a softening point of the nonionic surfactant is lower than a softening point of the anionic surfactant. 4. The thickness according to claim 1, wherein the thickness is 0.3 to ² mm, the basis weight is 15 to 50 g / m ² , and the surface resistivity is 10 ⁶ to 10 ¹² Ω / □. Polyethylene resin foam sheet.