JP5715896B2 - Laminated foam sheet - Google Patents

Description

  The present invention relates to a laminated foam sheet, and more particularly to a laminated foam sheet having at least one surface formed of a polyolefin resin layer.

A laminated foam sheet in which a resin layer in a substantially non-foamed state is laminated on one side or both sides of a foamed layer made of a resin foam sheet is flexible and excellent in cushioning properties. It is used for glass slip sheets (see Patent Document 1 below).
For example, glass substrates for flat panel displays such as liquid crystal displays and plasma displays are supplied from glass manufacturers to display manufacturers in a state where multiple sheets are laminated using a laminated foam sheet with a polyolefin resin layer on both sides as interleaving paper. ing.

In addition, this kind of glass substrate is used after the process of washing with water is once performed because there is a risk of causing troubles such as failure in the flat panel display if foreign matter is adhered to the surface. Yes.
For this reason, the laminated foam sheet used as a slip sheet is required to have a low possibility of foreign matter adhering to the surface of the glass substrate and to be easily removed by washing even if foreign matter is temporarily attached. It has been.

In response to such a demand, for example, when a polyolefin resin foam sheet is laminated on a glass substrate as a slip sheet, static electricity is generated by peeling electrification when the polyolefin resin foam sheet is peeled from the laminate. In order to prevent adhesion of dust and the like due to static electricity on the surface of the glass substrate, an antistatic agent is added to the resin layer of the laminated foam sheet.
As this type of antistatic agent, there are known a low molecular type used as a surfactant and a high molecular type such as an ion conductive polymer. It has a high prevention effect and, after the production of the laminated foamed sheet, has the effect of developing the antistatic effect at an early stage, while it may bleed out on the surface of the laminated foamed sheet and adhere to the glass substrate.

For this reason, for example, in Patent Document 1 below, a laminated foam sheet in which a polyolefin-based resin layer contains a polyalkylene oxide-based surfactant that can be easily washed and removed even if attached to the glass substrate is a glass substrate. It is described that it will be used for slip sheets.
Moreover, in the following Patent Document 1, a bleed of the surfactant is made by including in the polyolefin resin layer a polymer type antistatic agent that can be expected to function as a compatibilizer between the surfactant and the polyolefin resin. Out is suppressed.

JP 2010-42556 A

  As a conventional measure for avoiding troubles when using the glass substrate for flat panel display as described above, the deposit from the laminated foam sheet is suppressed as much as possible, and even if the deposit occurs, it can be easily washed away with water. It is mainly taken to make.

However, the components that migrate from the polyolefin resin layer to the surface of the glass substrate are not necessarily hydrophilic, such as surfactants, but are hydrophobic, such as low molecular weight components originally contained in polyolefin resins. Can be.
By the way, while surfactant is easy to transfer to the partner material which contacts, after the transfer, it exhibits the effect | action which suppresses other components contained in a polyolefin-type resin layer adhering to a partner material.
Therefore, if it is used in contact with a member that is expected to be washed with water, such as a glass substrate for a flat panel display, it is difficult to remove it. In order to prevent hydrophobic deposits, it may be preferable to contain a surfactant having a high migration property in the polyolefin resin layer.

However, since such an idea has not been achieved so far, a surfactant that can be easily removed by washing even if it adheres to a glass substrate or the like has not been included in the polyolefin-based resin layer in a state where it can easily bleed out.
Therefore, the conventional laminated foam sheet has a problem that it is not suitable for use as a slip sheet for a glass substrate for a flat panel display.

  This invention makes it a subject to solve such a problem, and makes it a subject to provide the laminated foam sheet suitable for using as a slip sheet etc. of the glass substrate for flat panel displays.

  The present invention relating to a polyolefin-based resin foam sheet for solving the above problems is a laminated foam sheet in which at least one surface is formed of a polyolefin-based resin layer, and the polyolefin-based resin layer includes: A polymer type antistatic agent and a solid anionic surfactant at 20 ° C. are contained together with a polyolefin resin, and 3 to 20 parts by mass of the polymer type antistatic agent with respect to 100 parts by mass of the polyolefin resin. In order to promote bleed out of the anionic surfactant, it is compatible with the anionic surfactant and is easier to bleed out than the anionic surfactant. It is characterized by further containing an accelerator.

In the present invention, the bleeding accelerator, Ru Oh propylene glycol.

  In the present invention, the anionic surfactant is preferably a sulfonate surfactant.

  Such a polyolefin resin foam sheet can be suitably used as a slip sheet for a glass substrate for a flat panel display.

Anionic surfactants, in particular, solid anionic surfactants at room temperature (for example, 20 ° C.) are generally easier to remove by washing than nonionic surfactants.
On the other hand, an anionic surfactant that is solid at room temperature tends to solidify in the foam sheet more easily than liquid at room temperature, and the uniformity of bleed-out tends to be impaired.
In the present invention, the polyolefin resin foam sheet contains a bleed-out accelerator that is compatible with a solid anionic surfactant at 20 ° C. and more easily bleed-out than an anionic surfactant at 20 ° C. I am letting.
Therefore, in the laminated foam sheet of the present invention, the bleed-out accelerator promotes bleed-out to the surface of the anionic surfactant that can be easily removed by washing with water.
That is, when used as a slip sheet for a glass substrate for a flat panel display, there is a substance that is difficult to remove by washing with water by quickly transferring the anionic surfactant to the surface of the material to be contacted. It can suppress adhering.

For the laminated foam sheet of the present invention, a multilayer foam sheet having a three-layer structure of polyolefin resin layer / foam layer / polyolefin resin layer in which a polyolefin resin layer is laminated on both sides of the polyolefin resin foam sheet by coextrusion is taken as an example. I will explain.
Moreover, in this embodiment, the case where this laminated foam sheet is used as a slip sheet for a glass substrate for a flat panel display will be described as an example.

In the laminated foam sheet according to this embodiment, the polyolefin resin layer is formed of a polyolefin resin composition containing a polymer type antistatic agent and a surfactant together with a polyolefin resin.
On the other hand, the foam layer composed of the polyolefin resin foam sheet is formed of a polyolefin resin composition containing a foaming component together with the polyolefin resin.

As the polyolefin resin for forming the foamed layer or the polyolefin resin layer, a polyolefin resin such as a polyethylene resin or a polypropylene resin can be used. Among them, a melt mass flow rate (hereinafter referred to as “MFR”) can be used. It is preferable to use a low density polyethylene resin having a resin density of 925 kg / m ³ or more and 935 kg / m ³ or less.
The foam layer and the polyolefin resin layer (hereinafter also simply referred to as “resin layer”) may be formed of the same polyolefin resin, or may be formed of different polyolefin resins.
Moreover, you may employ | adopt different polyolefin resin for the resin layer which forms one surface of a laminated foam sheet, and the resin layer which forms the other surface.

The MFR low-density polyethylene resin as described above is preferable when the MFR is less than 2 g / 10 min, causing problems in kneadability with the polymer antistatic agent in the extruder, and sufficient antistatic performance in the resin layer. This is because the foamed layer has a risk of causing foam breakage during extrusion foaming and not having a good foamed state.
In addition, if the MFR exceeds 6 g / 10 min, the melt tension becomes too low and it becomes difficult to obtain a low-density foam layer, and it becomes easy to generate a deposit in the tip of the die.

  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. The value measured by the method described in Method B (however, the test temperature is 190 ° C. and the load is 21.18 N) is intended. “Rate (MFR)” and “Melt Volume Flow Rate (MVR) Test Method”

The polyolefin resin constituting the laminated foam sheet of the present embodiment preferably has the above-described density. When the resin density is less than 925 kg / m ³ , foaming from the foam layer after extrusion is performed. Since the dispersion of the agent is fast and the rigidity of the resin itself is small, shrinkage may not be suppressed. On the other hand, if the resin density exceeds 935 kg / m ³ , the rigidity of the resin itself is too large and the laminated foam sheet This is because the cushioning property may be insufficient.

As the polymer antistatic agent constituting the resin layer together with the polyolefin 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 90 ° C. or more, crystallization proceeds in the extruder and dispersion becomes worse, and the antistatic agent This is because the distance between the dispersed particles becomes wider and it becomes difficult to develop an antistatic function commensurate with the amount added.

In addition, it is preferable that the MFR of the polymer antistatic agent is within the above-mentioned range. If the MFR of the polymer antistatic agent is less than 10 g / 10 min, 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.
Moreover, it is preferable that MFR is in the above-mentioned range because there is a possibility that dispersibility with a polyolefin resin may be lowered when a polymer type antistatic agent having an MFR exceeding 40 g / 10 min is used. .

In the present specification, the crystallization temperature is intended to be a value measured according to the method described in JIS K7122 “Method for measuring transition temperature of plastic” unless otherwise specified.
Specifically, using a differential scanning calorimeter (for example, “DSC 6220” manufactured by S.I. Nano Technology Co., Ltd.), about 6.5 mg of a sample is filled in a measurement container, and the nitrogen gas flow rate is 30 ml / min. The temperature is raised and cooled between 30 ° C. and 200 ° C. at a heating / cooling rate of 10 ° C./min, and the exothermic peak temperature during 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 containing a polyether block and a polyolefin block) may be employed. preferable.
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 “main component” means that the proportion of the polyether-polyolefin block copolymer in all the polymer antistatic agents contained 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 polyolefin resin composition constituting the resin layer, the blending ratio of the polyolefin resin and the polymer antistatic agent is such that the polymer antistatic agent is based on 100 parts by mass of the polyolefin resin. It is important that the ratio is 3 to 20 parts by mass.
It is important that the blending ratio of the polymer type antistatic agent in the polyolefin resin composition is within the above range. If it is less than the lower limit of the above range, the antistatic performance of the laminated foam sheet is insufficient, and the laminated foaming is caused by static electricity. This is because there is a risk of adhering dust to the sheet. If the content exceeds the upper limit of the above range, it is difficult to expect further improvement in the antistatic performance without only increasing the cost. .

The surfactant contained in the resin layer together with the polymer type antistatic agent functions as an antistatic agent as a so-called low molecular type antistatic agent. In this embodiment, the anionic interface that is solid at 20 ° C. It is important to employ an activator, and among these, it is preferable to employ an anionic surfactant having an HLB value of 20 or more (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, when the content of the anionic surfactant in the resin layer is excessive, 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 laminated foam sheet.
On the other hand, since there is a limit to improving the antistatic effect and the effect of suppressing deposits other than anionic surfactants, even if the anionic surfactant is included in the resin layer more than necessary, it is simply a laminated foam sheet. May be difficult to manufacture.
For this reason, it is important that the anionic surfactant is contained in the resin layer so that the ratio with respect to 100 parts by mass of the polyolefin resin is 0.1 to 5 parts by mass.

Among those exemplified above, the anionic surfactant contained in the resin layer is preferably a sulfonate surfactant in that it can be easily washed with water from the surface of the glass substrate, and the sulfonate interface. Among the activators, it is preferable to use any of dialkyl sulfosuccinate, linear alkylbenzene sulfonate, and alkyl sulfonate.
In addition, said anionic surfactant does not need to be used individually by 1 type, and may mix and use 2 or more types.

As a bleed-out accelerator for accelerating the bleed-out of this anionic surfactant, the bleed-out accelerator has compatibility with the anionic surfactant and is more likely to bleed out than the anionic surfactant at room temperature ( The liquid can be used at 20 ° C.).
As this bleed-out accelerator, for example, those exhibiting compatibility capable of dissolving an anionic surfactant at a concentration of 10% by mass or more at 20 ° C., preferably exhibiting compatibility capable of dissolving at a concentration of 40% by mass or more. Those are particularly preferred.
Note that the bleedout accelerator usually has its SP value deviated from the SP value of the polyolefin resin in order to promote the bleedout of the anionic surfactant, and such a bleedout accelerator should be adopted. Thus, an anionic surfactant having an SP value close to that of a polyolefin resin can be easily bleeded out.
Whether or not the bleedout accelerator is more likely to bleed out than the anionic surfactant can be determined from, for example, the SP value calculated based on the Fedors' estimation method. This can be determined by the large discrepancy.
For example, when a polyethylene resin having an SP value of 7 to 9 is used, the SP value of the bleed-out accelerator is preferably about 10 to 15, and the SP value of the anionic surfactant is preferably about 7 to 10. .

As this bleed-out accelerator, for example, propylene glycol, ethylene glycol, polyethylene glycol, propylene glycol phenyl ether, 1-3-butylene glycol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, ethylene glycol monoethyl ether, etc. can be used. Among these, propylene glycol is preferable in that it is excellent in the bleed-out promoting effect of the anionic surfactant and is easy to be removed by washing with water.
In addition, it is preferable that content of the said bleed-out accelerator contained in a foam sheet is normally 0.1-3 times by mass with respect to content of an anionic surfactant. More preferably, it is 0.2 to 1.5 times.

As for the type and amount of the anionic surfactant and the polymer antistatic agent, the resin layer forming one surface of the laminated foam sheet and the other surface are formed in the same manner as the polyolefin resin. It may be different depending on the resin layer.
In addition to these, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant, and a colorant can be contained in the resin layer as necessary.

The anionic surfactant, bleed-out accelerator, and polymer antistatic agent can be contained in the foamed layer if necessary, but it is usually less necessary to contain them in the foamed layer. In order to reduce the material cost of the laminated foam sheet, it is preferable not to contain them in the foam layer.
Examples of the foaming component to be contained in the foamed layer include a foaming agent and a cell regulator. Examples of the foaming agent include isobutane, normal butane, propane, pentane, hexane, cyclobutane, and cyclopentane. And inorganic gases such as hydrocarbons, 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 polyolefin-based resin is open-celled. In order to suppress the increase in the rate, it is possible to obtain a laminated foamed sheet which 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 polyolefin resin and the polymer-type 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 less than 5 parts by mass, it is difficult to obtain a sufficient foamed state. This is because coarse bubbles are likely to be formed.

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

The density of the foam layer (apparent density) is not particularly limited, and may be a density that allows the laminated foam sheet to exhibit cushioning properties that are generally required as a slip sheet of a glass substrate. Usually, it is less than 70 kg / m ³ , preferably 10 kg / m ³ or more and 60 kg / m ³ or less.
The reason why such a density is selected is that when the density is 70 kg / m ³ or more, the laminated foamed sheet has insufficient flexibility and may have low buffering properties, and the density is too small. This is because the foamed layer may not have sufficient strength, and as a result, the cushioning property of the laminated foamed sheet may be insufficient.
Furthermore, if the thickness of the cell membrane becomes too thin, the shrinkage increases, and as a result, when a long laminated foam sheet is produced, it becomes difficult to wind it as a roll.
Accordingly, the density of the foam layer is preferably 10 kg / m ³ or more, and more preferably 15 kg / m ³ or more.

The laminated foam sheet according to the present embodiment can be produced by general coextrusion in which a resin layer is extruded and laminated simultaneously with the foam layer. Instead of such a method, a polymer antistatic agent and an anion are used. A non-foamed resin sheet is produced by extruding a polyolefin-based resin composition containing a surfactant based on a flat die or the like, and the resin sheet is not completely cooled, and is bonded to a separately produced resin foam sheet. Can also be produced.
Further, the laminated foamed sheet of the present invention can also be produced using a method in which a non-foamed resin sheet and a resin foamed sheet are produced completely separately, and these are heat laminated and laminated.

The polyolefin-based resin layer and the foamed layer do not need to be directly laminated, and another resin layer or the like may be interposed between the polyolefin-based resin layer and the foamed layer.
Therefore, in this embodiment, the foam layer is also formed using a polyolefin resin in the same manner as the resin layer in that the resin layer and the foam layer can be easily laminated and integrated by coextrusion. It is also possible to dry laminate the foamed sheet to form a polyolefin resin layer.
For example, a dry laminate sheet is produced by bonding a resin sheet made of a polyolefin resin composition containing a polymeric antistatic agent and an anionic surfactant and a polystyrene resin sheet with an adhesive, and the dry laminate sheet A laminated foamed sheet having a laminated structure of polyolefin resin layer / adhesive layer / polystyrene resin layer / foamed layer obtained by laminating the above to a polystyrene resin foamed sheet is also within the intended range as the laminated foamed sheet of the present invention. is there.

Moreover, in this embodiment, although the case where a laminated foam sheet is used as a slip sheet of a glass substrate is illustrated, the use of the laminate foam sheet of the present invention is not limited to a slip sheet of a glass substrate. If a member other than the substrate is planned to be washed with water, the same effect as in the case of using it as a slip sheet of the glass substrate can be expected by using it for packaging or the like.
In such a case, the resin layer can be provided only on the side in contact with the member to be packaged, and the resin layer can be omitted on the opposite side.
That is, in the present embodiment, a laminated foam sheet having a three-layer structure in which resin layers are provided on both sides of the foam layer is illustrated, but a laminated foam sheet having a two-layer structure having a resin layer only on one side of the foam layer is also illustrated. This is within the scope of the present invention.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

Example 1
A raw material for forming a foam layer is supplied to one of two extruders connected to the confluence mold, and a raw material for forming a resin layer is supplied to the other to perform co-extrusion. / A laminated foam sheet having a three-layer structure of resin layers was produced.
The foam layer is Sankyo Kasei Co., Ltd. based on 100 parts by mass of low density polyethylene resin (trade name: “LF580”, density: 929 kg / m ³ , MFR = 4.0 g / 10 min) manufactured by Nippon Polyethylene Co., Ltd. 0.05 part by mass of an air-conditioning agent masterbatch (azodicarbonamide-containing masterbatch: trade name “Cermic MB1023”) and a blowing agent (normal butane / isobutane = 50/50, mass ratio) 6.2 It was formed by the formulation contained in the ratio of parts by mass.
On the other hand, the resin layer is Sanyo Chemical Co., Ltd. with respect to 100 parts by mass of low density polyethylene resin (trade name: “LF580”, density: 929 kg / m ³ , MFR = 4.0 g / 10 min) manufactured by Nippon Polyethylene Co., Ltd. 7 parts by mass of a polymer antistatic agent (polyether-polypropylene block copolymer, trade name: “Pelestat 300”, crystallization temperature: 85.4 ° C., MFR = 30 g / 10 min) manufactured by company, 12 carbon atoms 0.9 parts by mass of “Chemistat 3033” (trade name) manufactured by Sanyo Chemical Co., Ltd. containing 90% by mass or more of ˜16 alkyl sulfonates (softening point 70 ° C., HLB value 40), manufactured by Asahi Glass Co., Ltd. It was formed by a blend containing propylene glycol (melting point: -59 ° C, liquid at normal temperature (20 ° C)) at a ratio of 0.6 parts by mass.
The anionic surfactant (Chemist 3033) and bleed out accelerator (propylene glycol) were melt kneaded into the polyolefin resin in such a manner that a premixed solution was press-fitted from the middle of the extruder.

The thickness of the obtained laminated foamed sheet was measured using a constant pressure thickness measuring machine (Model PG- (special) S-37387 ("SCM-627") manufactured by Teclock Co., Ltd.), and the density (apparent density) was 0.5 mm. ) Was measured based on JIS K 7222: 2005 “Foamed Plastics and Rubbers—How to Obtain Apparent Density” and found to be 51 kg / m ³ .

Moreover, the suitability of the glass substrate as a slip sheet was determined by the contact angle as follows.
First, the laminated 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 the entire laminated foam sheet is loaded. 1kg weight is added so that it is added and left in a constant temperature and humidity chamber (trade name “HPAV-120-40”, manufactured by ISUZU Seisakusho) at a temperature of 60 ° C. and a relative humidity of 80% for 24 hours, and then a temperature of 30 ° C. And dried for 24 hours at 0% relative humidity.
The contact angle of purified water on the surface of the glass plate that was in contact with the laminated foam sheet was measured by a solid-liquid interface analyzer (trade name “DROP MASTER300”) manufactured by Kyowa Interface Chemical Co., Ltd., and used as the contact angle before washing.
Similarly, a laminated foam sheet was applied under load, and a glass plate subjected to treatment at 60 ° C., 80% RH × 24 hours−30 ° C. 0% RH × 24 hours was used as a household alkaline detergent (manufactured by Kao Corporation, The product was washed with washing water containing 0.4% of the trade name “Attack”, rinsed with distilled water, and then dried at a temperature of 30 ° C. and a relative humidity of 0% for 24 hours.
The contact angle of the glass plate after washing with water was measured and used as the contact angle after washing.
In addition, the contact angle before washing | cleaning and the contact angle after washing | cleaning measured 20 points, respectively, and computed it with the average value.
As a result, the contact angle before washing was 7 degrees, and the contact angle after washing was 6 degrees, and excellent detergency was confirmed.

(Examples 2 to 5)
A foamed sheet was prepared in the same manner as in Example 1 except that the type and amount of the anionic surfactant and bleed-out accelerator to be contained in the laminated foamed sheet were evaluated and evaluated in the same manner as in Example 1. It was.
In Example 2, a linear alkyl benzene sulfonate (softening point 270 ° C., HLB value 36.2) such as dodecyl benzene sulfonate manufactured by Kao Corporation was used as a main component (linear alkyl benzene sulfonate of about 60 mass). In the examples 4 and 5, “ethylene glycol” was used as a bleed-out accelerator.

(Comparative Examples 1 and 2)
A laminated foam sheet was prepared in the same manner as in Example 1 except that a nonionic surfactant was included instead of the anionic surfactant, and evaluation was performed in the same manner as in Example 1.
In Comparative Example 2, diglycerin monooleate (trade name “ESR720”, softening point 40 ° C., HLB value 9.0) manufactured by Riken Vitamin Co., Ltd. was used as a nonionic surfactant. In Comparative Example 3, As the nonionic surfactant, stearyl monoglycerin (trade name “PV-100”) manufactured by Riken Vitamin Co., Ltd. was used.

(Comparative Examples 3 and 4)
A laminated foam sheet was prepared in the same manner as in Example 1 except that an anionic surfactant was contained, and evaluation was performed in the same manner as in Example 1.
In Comparative Example 3, only polypropylene glycol functioning as a bleedout accelerator was contained, and in Comparative Example 4, neither an anionic surfactant nor a bleedout accelerator was contained.
The evaluation results of these examples and comparative examples are shown in Table 1 below.

  From the results shown in the above table, it can be seen that the laminated foam sheet of the present invention is useful for a slip sheet of a glass substrate.

Claims (3)

A laminated foam sheet in which at least one surface is formed of a polyolefin resin layer,
The polyolefin-based resin layer contains a polymer-type antistatic agent and a solid anionic surfactant at 20 ° C. together with the polyolefin-based resin, and the polymer-type charged with respect to 100 parts by mass of the polyolefin-based resin. 3 to 20 parts by weight of an inhibitor is contained and has compatibility with the anionic surfactant to promote bleedout of the anionic surfactant and bleeds out from the anionic surfactant. A laminated foamed sheet characterized in that it further contains a bleedout accelerator that is liquid at 20 ° C. , and the bleedout accelerator is propylene glycol . The anionic laminated foam sheet as claimed in claim 1 Symbol placement surfactant is a sulfonic acid salt-based surfactant. The laminated foam sheet according to claim 1 or 2, which is used as a slip sheet for a glass substrate for a flat panel display.