JP2019209535A - Polyolefinic resin laminated foam sheet and interleaf paper for glass plate made of the laminated foam sheet - Google Patents

Abstract

To provide a laminated foam sheet capable of imparting excellent cleaning property to an article to be packaged such as a glass plate even under high temperature and high humidity, as a laminated foam sheet usable as an interleaf paper for glass plate, and to provide an interleaf paper for glass plate using the laminated foam sheet.SOLUTION: There is provided a laminated foam sheet having a polyolefinic resin foam layer and a polyolefinic resin surface layer laminated and bonded to at least one side of the foam layer. Polyethylene glycol (PEG) is blended into said surface layer and said polyethylene glycol (PEG) consists of a first polyethylene glycol (PEG 1) which is liquid at 25°C and a second polyethylene glycol (PEG 2) which is solid at 25°C. A blending amount of said first polyethylene glycol (PEG 1) in said surface layer is 0.5 pts.mass or more and 10 pts.mass or less with respect to 100 pts.mass of the polyolefinic resin constituting the surface layer. The blending amount of said second polyethylene glycol (PEG 2) in the surface layer is 3 pts.mass or more based on 100 pts.mass of the first polyethylene glycol (PEG 1) in said surface layer.SELECTED DRAWING: None

Description

  The present invention relates to a polyolefin-based resin laminated foam sheet and a glass sheet interleaf made of the laminated foam sheet.

  Polyolefin-based resin laminated foam sheets have been widely used as packaging materials for home appliances, glass appliances, ceramics, and the like because they are excellent in flexibility and cushioning properties and can prevent damages and scratches on the objects to be packaged. In addition, in recent years, polyolefin resin-laminated foam sheets have been widely used as glass sheet interlayers used in the manufacture of display panels such as liquid crystal displays, plasma displays, and electroluminescent displays as flat TVs have been developed and demand expanded. ing.

  Glass plate interleaving paper is a sheet material that is used by being interposed between glass plates. In general, a glass sheet interleaf is used to prevent the glass sheet from being damaged or damaged when handling a plurality of glass sheets such as storage and transportation of the glass sheet.

  With higher definition of displays, higher quality is required for glass plates for displays. When a glass plate is used, the surface of the glass plate is generally cleaned with water or the like. For this reason, about the glass plate, it is calculated | required that the surface state can be made into a very clean state by washing | cleaning. Therefore, for glass interleaving paper, one that does not impair the washability of the packaged object such as a glass plate or one that can impart excellent detergency to the packaged object such as a glass plate is required. It has been.

  Regarding this point, for example, Patent Document 1 proposes a polyolefin-based resin laminated foam sheet in which a surface layer contains a hydrophilic compound such as polyethylene glycol. When this polyolefin-based resin laminated foam sheet is used as a packaging sheet, the cleaning property of the packaged product packaged with the packaging sheet is improved, and the packaged product with water or the like even when foreign matter is transferred By carrying out this cleaning, the dirt on the surface of the package can be easily removed.

JP 2010-42556 A

  In recent years, objects to be packaged such as glass plates have been placed in a hot and humid atmosphere during storage or transportation. When a conventional polyolefin-based resin laminated foam sheet is used in a high-temperature and high-humidity atmosphere, there may be a case where the cleaning property of an object to be packaged such as a glass plate is slightly insufficient.

  The present invention provides a laminated foam sheet capable of imparting excellent detergency to an article to be packaged such as a glass sheet even under high temperature and high humidity, and for a glass sheet using such a laminated foam sheet. The purpose is to provide a slip.

The present invention is a laminated foam sheet having (1) a polyolefin resin foam layer and a polyolefin resin surface layer laminated and adhered to at least one side of the foam layer,
In the surface layer, polyethylene glycol (PEG) is blended,
The polyethylene glycol (PEG) comprises a first polyethylene glycol (PEG1) that is liquid at 25 ° C. and a second polyethylene glycol (PEG 2) that is solid at 25 ° C.,
The blending amount of the first polyethylene glycol (PEG1) in the surface layer is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer,
The amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass or more with respect to 100 parts by mass of the first polyethylene glycol (PEG1) in the surface layer. Polyolefin resin laminated foam sheet,
(2) The polyolefin-based resin laminated foam sheet according to (1) above, wherein the number average molecular weight of the first polyethylene glycol (PEG1) is 100 or more and 800 or less,
(3) The polyolefin-based resin laminated foam sheet according to (1) or (2) above, wherein the number average molecular weight of the second polyethylene glycol (PEG2) is 2000 or more,
(4) The polyolefin resin laminated foam sheet according to any one of (1) to (3) above, wherein the freezing point of the second polyethylene glycol (PEG2) is a temperature exceeding 50 ° C.
(5) The blending amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the blending amount of the first polyethylene glycol (PEG1) in the surface layer. The polyolefin-based resin laminated foam sheet according to any one of (1) to (4) above,
(6) Any one of (1) to (5) above, wherein the total blending amount of the polyethylene glycol (PEG) with respect to 100 parts by mass of the polyolefin resin constituting the surface layer is 15 parts by mass or less. The polyolefin-based resin laminated foam sheet according to Item,
(7) A polymer antistatic agent is blended in the surface layer, and the blending amount of the polymer antistatic agent is 2 to 30 parts by mass with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. The polyolefin-based resin laminated foam sheet according to any one of (1) to (6) above, wherein the polyolefin-based resin laminated foam sheet is not more than part by mass,
(8) The polyolefin resin constituting the foam layer is low density polyethylene,
The polyolefin resin laminated foam sheet according to any one of (1) to (7), wherein the polyolefin resin constituting the surface layer is low-density polyethylene,
(9) The gist is a glass sheet interleaf made of the polyolefin resin-laminated foam sheet according to any one of (1) to (8) above.

  The laminated foamed sheet of the present invention is a polyolefin-based resin laminated foamed sheet that can impart excellent detergency to an object to be packaged such as a glass plate even under high temperature and humidity. Moreover, the interleaf paper for glass plates of the present invention using the laminated foam sheet can impart excellent cleaning properties to the glass plates even under high temperature and high humidity.

  The laminated foam sheet of the present invention has a polyolefin resin foam layer (hereinafter sometimes simply referred to as a foam layer) and a polyolefin resin surface layer (hereinafter sometimes simply referred to as a surface layer).

(Average thickness of laminated foam sheet)
Although there is no restriction | limiting in particular in the average thickness of the laminated foam sheet of this invention, The average thickness of a laminated foam sheet is about 0.05 mm or more and 10 mm or less in general. When the average thickness of the laminated foamed sheet is within the above range, sufficient buffering properties can be secured without being bulky even when used as a glass sheet interleaf. From the above viewpoint, the average thickness of the laminated foam sheet is preferably 0.07 mm to 1.0 mm, more preferably 0.1 to 0.5 mm, and still more preferably 0.12 mm to 0.3 mm.

(Specification of average thickness of laminated foam sheet)
The average thickness of the laminated foamed sheet in the present invention is specified as an arithmetic average value of the total thickness (mm) of the laminated foamed sheet measured at 1 cm intervals in the width direction over the entire width of the laminated foamed sheet. For example, when a laminated foam sheet is produced by a production method using an extruder, the width direction indicates a direction along the laminated foam sheet surface and a direction orthogonal to the extrusion direction of the laminated foam sheet. .

(Foam layer)
The foam layer of the laminated foam sheet of the present invention is a layer formed of a foam having a polyolefin resin as a base resin. The polyolefin resin used as the base resin is a resin in which the proportion of the component units derived from the olefin monomer is 50 mol% or more. Examples of the polyolefin resin include a polyethylene resin, a polypropylene resin, and a polybutene resin. Of the polyolefin resins, polyethylene resins are particularly preferable because they are more flexible.

  Examples of the polyethylene resin include high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-1-butene copolymer, ethylene. -Butene-1 copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-octene copolymer, and a mixture of two or more thereof. It is done.

Among these polyethylene resins, low density polyethylene is preferable. The low density polyethylene had a density of 890 kg / ^{m 3} or more 935 kg / ^{m 3} or less of the polyethylene resin, preferably a density of 900 kg / ^{m 3} or more 930 kg / ^{m 3} or less of the polyethylene resin.

  Examples of polypropylene resins include propylene homopolymers and copolymers of propylene and other olefins. Examples of other olefins copolymerizable with propylene include ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1 Examples thereof include α-olefins having 4 to 10 carbon atoms such as heptene and 3-methyl-1-hexene.

  To the polyolefin resin, other resins such as a styrene resin, an elastomer such as an ethylene propylene rubber or a styrene-butadiene-styrene block copolymer, and the like may be added as long as the effects of the present invention are not impaired. In that case, the addition amount of the other resin or elastomer is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, and more preferably 5 parts by mass when the addition amount of the polyolefin resin constituting the foam layer is 100 parts by mass. The following are particularly preferred:

  Moreover, you may add an additive to polyolefin resin in the range which does not inhibit the effect of this invention. Examples of additives include air conditioners, nucleating agents, antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, antibacterial agents, antishrink agents, etc., inorganic fillers, etc. Can be mentioned.

(Apparent density of laminated foam sheet)
The apparent density of the laminated foam sheet of the present invention is preferably 20 kg / m ³ or more and 450 kg / m ³ or less. When the apparent density of the laminated foamed sheet is within the above range, the laminated foamed sheet is excellent in flexibility and mechanical strength such as shape retention and compressive strength. From the viewpoint of flexibility of the laminated foam sheet, the upper limit of the apparent density is preferably 300 kg / m ³ , more preferably 200 kg / m ³ . Further, from the viewpoint of mechanical strength and stiffness strength of the laminated foam sheet, the lower limit of the apparent density is preferably 30 kg / m ³ , more preferably 40 kg / m ³ , and still more preferably 50 kg / m ³ .

The apparent density of the laminated foamed sheet is specified from a value obtained by cutting a test piece from the laminated foamed sheet and dividing the mass (kg) of the test piece by the volume (m ³ ) obtained from the external dimensions of the test piece.

(Surface layer)
The surface layer of the laminated foam sheet of the present invention is laminated and adhered to at least one side of the front and back surfaces of the foam layer, and is located on the outermost surface side of the laminated foam sheet. An intermediate layer may be formed between the foam layer and the surface layer. As an intermediate | middle layer, the layer which consists of resin which has adhesiveness with respect to both a foam layer and a surface layer can be mentioned, for example.

  A surface layer is a layer formed with the resin composition which uses polyolefin resin as base resin. As the polyolefin resin used as the base resin, and other resins and additives blended therein, the same materials as those described above for the foamed layer may be used.

  In the laminated foam sheet of the present invention, the polyolefin resin constituting the foam layer and the surface layer may be the same resin, or different resins may be used for the foam layer and the surface layer. When the foamed layer and the surface layer are formed of the same type of resin as the laminated foamed sheet, the adhesiveness between the foamed layer and the surface layer is high. From the viewpoint of adhesiveness between the foam layer and the surface layer, it is preferable to use low density polyethylene for the surface layer.

The basis weight of the surface layer, the single-sided, is preferably 0.5 g / ^{m 2} or more, more preferably 0.7 g / ^{m 2} or more, 1.0 g / ^{m 2} or more is more preferable. When the basis weight of the surface layer satisfies the above range, the desired cleanability of the package is sufficiently enhanced. The upper limit of the basis weight of the surface layer is not particularly limited from the viewpoint of the washability of the packaged object, but the upper limit is preferably 100 g / m ² from the viewpoint of buffering properties and light weight, and 60 g / m ^2. m ² is more preferable, and 50 g / m ² is even more preferable.

The basis weight [g / m ² ] of the surface layer in the present invention is the discharge amount X [kg / kg] of the surface layer when the laminated foam sheet is produced when the laminated foam sheet is produced by a production method using an extruder. h], the width W [m] of the obtained laminated foamed sheet, and the length L [m / h] per unit time of the laminated foamed sheet can be obtained by the following formula (1). In addition, when laminating | stacking a surface layer on the both surfaces side of a foaming layer, the basic weight of each surface layer is calculated | required from the discharge amount of each surface layer.

(Polyethylene glycol (PEG))
Polyethylene glycol (PEG) is blended in the surface layer of the laminated foam sheet of the present invention. The polyethylene glycol (PEG) blended in the surface layer is composed of a first polyethylene glycol (PEG1) and a second polyethylene glycol (PEG2).

  Even if the laminated foam sheet of the present invention is placed in a high-temperature and high-humidity atmosphere, it can impart excellent cleaning properties to an article to be packaged such as a glass plate. The reason why the laminated foam sheet of the present invention can impart excellent cleaning properties to a packaged object even under high temperature and humidity is not clear, but the following two reasons can be considered. .

  First, since the laminated foam sheet of the present invention is blended with the second polyethylene glycol that is solid at 25 ° C. together with the first polyethylene glycol that is liquid at 25 ° C., the water absorption rate of the laminated foam sheet is kept low. It will be a thing. Therefore, even if it is placed in a hot and humid atmosphere, it is considered that dust and dirt are less likely to adhere to the surface of the laminated foam sheet. For this reason, when a laminated foam sheet is used as a packaging material, it is possible to effectively suppress the possibility that dust or dirt adheres to the package object via the laminated foam sheet and the package object is contaminated. Furthermore, because the water absorption rate of the laminated foam sheet is kept low, impurities such as organic substances in the air that cause dirt and hydrogen ions and calcium ions contained in the moisture, together with moisture in the air, enter the laminated foam sheet. It is considered that the risk of adhesion can be suppressed.

  Secondly, since the laminated foam sheet of the present invention is blended with the second polyethylene glycol that is solid at 25 ° C. together with the first polyethylene glycol that is liquid at 25 ° C., it is assumed that the laminated foam sheet was placed in a hot and humid atmosphere. In addition, it is considered that the first polyethylene glycol bleeds out more uniformly from the surface layer to the package. Therefore, it is considered that the cleaning unevenness of the packaged object is suppressed at the time of cleaning the packaged object.

  For these reasons, it is considered that the laminated foam sheet of the present invention can impart excellent cleaning properties to the package even under high temperature and high humidity.

(Polyethylene glycol content)
The total amount of polyethylene glycol (PEG) in the surface layer is preferably 15 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. When the total blending amount of polyethylene glycol (PEG) in the surface layer is within the above range, it is possible to impart more excellent cleaning properties to an object to be packaged such as a glass plate even in a hot and humid atmosphere. It becomes a laminated foam sheet. From the above viewpoint, the upper limit of the blending amount of polyethylene glycol (PEG) is more preferably 12 parts by mass, and still more preferably 10 parts by mass. Moreover, it is preferable that the minimum of the compounding quantity of polyethyleneglycol is 0.5 mass part, and it is more preferable that it is 1.0 mass part.

(First polyethylene glycol (PEG1))
The first polyethylene glycol (PEG1) in the surface layer is a polyethylene glycol that is liquid at 25 ° C. When the first polyethylene glycol is liquid at 25 ° C., the first polyethylene glycol is more likely to bleed out from the surface layer, and excellent cleaning properties can be imparted to the package. From the above viewpoint, the first polyethylene glycol (PEG1) is more preferably liquid at 23 ° C., further preferably liquid at 10 ° C., and particularly preferably liquid at 0 ° C.

(Number average molecular weight of the first polyethylene glycol (PEG1))
The number average molecular weight of the first polyethylene glycol (PEG1) is 100 or more and 800 or less from the viewpoint that PEG1 is likely to bleed out from the surface layer as described in the description of the temperature at which PEG1 is a liquid. Is preferably 150 or more and 700 or less, more preferably 200 or more and 600 or less.

(Identification method of number average molecular weight)
The number average molecular weight of the first polyethylene glycol can be determined by a known method calculated from the hydroxyl value.

(Amount of the first polyethylene glycol blended)
The blending amount of the first polyethylene glycol (PEG1) in the surface layer is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. When the ratio of the blending amount of the first polyethylene glycol is within the above range, the laminated foamed sheet can impart better cleaning properties to the package. From the above viewpoint, the blending amount of the first polyethylene glycol is more preferably 1.0 part by mass or more and 8 parts by mass or less, and further preferably 2 parts by mass or more and 6 parts by mass or less.

  The first polyethylene glycol can be obtained from the market. Examples of commercially available products that can be used as the first polyethylene glycol in the present invention include “Polyethylene Glycol 300” manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.

(Second polyethylene glycol (PEG2))
The second polyethylene glycol (PEG2) in the surface layer is a polyethylene glycol that is solid at 25 ° C. The second polyethylene glycol (PEG2) that is solid at 25 ° C. is blended in the surface layer of the laminated foamed sheet together with the first polyethylene that is liquid at 25 ° C., so that the laminated foamed sheet is in a hot and humid atmosphere. Even if it is placed on the packaging, it is possible to impart more excellent cleaning properties to an article to be packaged such as a glass plate.

(Number average molecular weight of the second polyethylene glycol (PEG2))
From the viewpoint of further improving the cleanability of a packaged object such as a glass plate under high temperature and high humidity, the number average molecular weight of the second polyethylene glycol (PEG2) is preferably 2000 or more, and preferably 2500 or more. Is more preferable and 3000 or more is still more preferable. The upper limit of the number average molecular weight of the second polyethylene glycol is about 20000.

(Identification method of number average molecular weight)
The number average molecular weight of the second polyethylene glycol can be determined by the same method as the number average molecular weight of the first polyethylene glycol.

(Freezing point of the second polyethylene glycol (PEG2))
Furthermore, it is preferable that the freezing point of the second polyethylene glycol (PEG2) is higher than 50 ° C. from the viewpoint of further improving the cleanability of the article to be packaged such as a glass plate under high temperature and high humidity. More preferably, it is more preferably 55 ° C. or higher. The upper limit of the freezing point of the second polyethylene glycol is about 65 ° C.

(Method for identifying freezing point)
The freezing point of the second polyethylene glycol can be determined by the method described in JIS K 0065 (1992).

(Blend amount of second polyethylene glycol)
The compounding amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass or more with respect to 100 parts by mass of the compounding amount of the first polyethylene glycol (PEG1) in the surface layer. If the blending amount of the second polyethylene glycol (PEG2) is too small, there is a possibility that sufficient cleaning properties cannot be imparted to an object to be packaged such as a glass plate when placed in a hot and humid atmosphere. From the above viewpoint, the amount of the second polyethylene glycol (PEG2) in the surface layer is more than 5 parts by mass with respect to 100 parts by mass of the first polyethylene glycol (PEG1) in the surface layer. preferable.

  The upper limit of the amount of the second polyethylene glycol (PEG2) in the surface layer is not particularly limited, but from the viewpoint of the production stability of the laminated foam sheet, the amount of the first polyethylene glycol (PEG1) in the surface layer is 100. It is preferable that it is 100 mass parts or less with respect to a mass part.

  The second polyethylene glycol can be obtained from the market. Examples of commercially available products that can be used as the second polyethylene glycol in the present invention include “Polyethylene Glycol 6000” manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.

  Furthermore, since the laminated foam sheet of the present invention contains the second polyethylene glycol together with the first polyethylene glycol in the surface layer, the peel strength with respect to the package is small even under a high temperature and humidity atmosphere. Become. For this reason, for example, when lifting and taking out the package, the possibility that the packaging material made of the laminated foam sheet will be lifted together with the package after following the package is suppressed, and when using the package The workability can be improved.

(Antistatic agent)
In the laminated foam sheet of the present invention, an antistatic agent may be blended in the surface layer as long as the object effects of the present invention are not impaired. As the antistatic agent, it is preferable to use a polymer type antistatic agent. Examples of the polymer type antistatic agent include polyether-polyolefin copolymers and ionomer resins. Examples of polyether-polyolefin copolymers include “Pelestat (trademark) VL300”, “Pelestat HC250”, “Peletron (trademark) HS”, “Peletron PVH”, and “Peletron LMP” manufactured by Sanyo Chemical Industries, Ltd. And the like are commercially available. Examples of the ionomer resin include those commercially available under trade names such as “ENTILA (trademark) SD100” and “ENTILA MK400” manufactured by Mitsui DuPont Polychemical Co., Ltd.

(Surface resistivity)
The surface resistivity of the laminated foam sheet of the present invention is preferably 1 × 10 ⁸ Ω or more and 1 × 10 ¹⁴ Ω or less. When the surface resistivity of the laminated foamed sheet is within the above range, the laminated foamed sheet exhibits sufficient antistatic properties. From the above viewpoint, the surface resistivity of the laminated foam sheet is preferably 5 × 10 ¹³ Ω or less, more preferably 1 × 10 ¹³ Ω or less.

  The surface resistivity of the laminated foam sheet is measured according to JIS K 6271 (2008). That is, the test piece cut into a predetermined size including the surface of the laminated foamed sheet is left in an atmosphere of a temperature of 20 ° C. and a relative humidity of 30% for 36 hours to adjust the state of the test piece. The surface of the surface layer of the laminated foamed sheet of the test piece is one minute after the voltage application is started under the condition of an applied voltage of 500 V in accordance with JIS K 6271 (2008) using the state-adjusted test piece. The surface resistivity of a part is calculated | required and this is made into the surface resistivity of a laminated foam sheet.

  The blending amount of the polymer type antistatic agent is preferably 2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. When the blending amount of the antistatic agent is within the above range, the laminated foam sheet has excellent antistatic performance. From the above viewpoint, the blending amount of the antistatic agent is preferably 3 parts by mass or more and 25 parts by mass or less, and preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. Preferably there is.

(Method for producing laminated foam sheet)
The laminated foam sheet of the present invention can be produced, for example, by a coextrusion method using an annular die. First, a polyolefin resin for forming a foam layer and an additive such as a bubble adjusting agent added as necessary are supplied to an extruder for forming a foam layer, and a mixture of the polyolefin resin and the additive is heated and kneaded. Further, a physical foaming agent is further injected, and the mixture and the physical foaming agent are further kneaded to obtain a resin melt for forming a foam layer. On the other hand, a polyolefin resin for forming the surface layer, polyethylene glycol, and additives such as an antistatic agent added as necessary are supplied to the extruder for forming the surface layer, and heated and kneaded to form the surface layer. A resin melt is obtained. Thereafter, the foamed layer-forming resin melt and the surface layer-forming resin melt are introduced into a coextrusion annular die, and coextrusion foaming is performed to obtain a cylindrical laminated foam in which the surface layer is laminated on the foamed layer. The laminated foamed sheet can be obtained by opening the tubular laminated foam while expanding the diameter and taking it out.

  In obtaining the resin melt for forming the surface layer in the method for producing a laminated foam sheet, polyethylene glycol is added, that is, the first polyethylene glycol and the second polyethylene glycol are added. At this time, the method for adding the first polyethylene glycol and the second polyethylene glycol is not particularly limited. For example, the first polyethylene glycol and the second polyethylene glycol may be simultaneously supplied to the surface layer forming extruder, or may be separately supplied to the surface layer forming extruder. The second polyethylene glycol may be supplied to the surface layer forming extruder together with the polyolefin-based resin, heated in advance to be liquid, and supplied to the surface layer forming extruder using a submerged pump or the like. Good. The first polyethylene glycol may be supplied to the surface layer forming extruder using a submerged pump. In addition, a master batch obtained by kneading the first polyethylene glycol and the second polyethylene glycol with the polyolefin resin for forming the surface layer in advance may be supplied to the extruder for forming the surface layer.

  As the cell regulator used for forming the foamed layer, any organic or inorganic material can be used without particular limitation. Examples of the inorganic foam regulator include borate metal salts such as zinc borate, magnesium borate, borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, calcium bicarbonate, and the like. Examples of the organic foam regulator include sodium phosphate-2,2-methylenebis (4,6-tert-butylphenyl), sodium benzoate, calcium benzoate, aluminum benzoate, and sodium stearate. it can. A combination of citric acid and sodium bicarbonate, a combination of an alkali salt of citric acid and sodium bicarbonate, or the like can also be used as the bubble regulator. Further, two or more kinds of these exemplified bubble regulators may be mixed and used.

  Moreover, as a bubble regulator, it is preferable to use a talc from a viewpoint which is easy to adjust the bubble diameter of a foamed layer among the above-mentioned. In addition, it is preferable to add a bubble regulator in the range of about 0.1 mass part or more and 3 mass parts or less with respect to 100 mass parts of polyolefin resin which comprises a foamed layer, More preferably, 0.2 mass part The amount is 2 parts by mass or less.

  The physical foaming agent is not particularly limited as long as it can be applied to the production of the foamed layer of the laminated foam sheet. As the physical foaming agent, an inorganic physical foaming agent or an organic physical foaming agent can be used. Examples of the inorganic physical foaming agent include oxygen, nitrogen, carbon dioxide, and air. Examples of the organic physical foaming agent include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, isohexane and cyclohexane, chlorinated hydrocarbons such as methyl chloride and ethyl chloride, 1,1, Fluorinated hydrocarbons such as 1,2-tetrafluoroethane, 1,1-difluoroethane, 1,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, dimethyl ether, methylethyl Examples thereof include ethers such as ether, and alcohols such as methanol and ethanol. Furthermore, the above physical foaming agents may be used in combination of two or more.

  Among these physical foaming agents, from the viewpoint that the coextrusion method can be stably performed and a good foamed layer can be stably obtained, the physical foaming agent is normal butane, isobutane, or these It is preferable to use a mixture.

(Glass plate interleaving paper)
The laminated foam sheet of the present invention can be used as an interleaf for glass plates. The interleaf paper for glass plates can be used by being interposed between glass plates, and can prevent the possibility of breakage due to contact between the glass plates. Examples of the glass plate using such a glass plate interleaving paper include a glass plate for a liquid crystal display. When using a glass plate for a liquid crystal display, the glass plates are usually washed with water after the interleaving paper for the glass plates interposed between the glass plates is removed, and then washed. Is used. At this time, if dust, dust, organic matter, or the like is in contact with the glass plate surface, it is difficult to wash away the dust, dust, organic matter, etc. with water or the like. In this regard, when the interleaf paper for the glass plate is composed of the laminated foam sheet of the present invention, the polyethylene glycol has successfully transferred from the laminated foam sheet to the surface of the glass plate, and each glass plate is washed with water or the like. In doing so, dust, dirt, organic matter, etc. adhering to the surface of the glass plate can be easily washed.

  Further, the glass plate interleaving paper may be placed in a high-temperature and high-humidity atmosphere while being interposed between the glass plates. In this regard, when the interleaf paper for glass plate is made of the laminated foam sheet of the present invention, the water absorption rate of the laminated laminated sheet is kept low, and even if it is placed in a hot and humid atmosphere, Dust, dust, organic matter, etc. hardly adhere to the surface of the foam sheet. Therefore, it is possible to effectively suppress the possibility that dust, dirt, organic matter, etc. adhere to the glass plate via the laminated foam sheet and the glass plate is contaminated.

  Furthermore, since the laminated foam sheet of the present invention has a low peel strength from the packaged object even in a high-temperature and humid atmosphere as described above, for example, when the plate-shaped packaged object is lifted and taken out, the laminated foamed sheet The sheet is not lifted together with the packaged object following the packaged object, and the workability is improved. Also from this point, the laminated foamed sheet of the present invention can be suitably used as a glass sheet interleaf.

  The laminated foam sheet of the present invention is not limited to one in which the surface layer is laminated on only one side of the foam layer, but may be one in which the surface layer is laminated on both sides. When used as a board interleaf, the surface layer is preferably laminated on both sides of the foam layer. By providing a surface layer on both sides of the foam layer, when the glass sheet interleaving paper is interposed between the glass plates and used, both of the two glass plates in contact with the glass sheet interleaving paper, Contamination can be reduced and cleaning properties can be improved.

  Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the examples.

As the polyolefin resin, low-density polyethylene (density 922 kg / m ³ ) (indicated by abbreviation LDPE1 in Table 2) (manufactured by NUC, grade name NUC8321) was used.

  As polyethylene glycol (indicated by the abbreviation PEG in Tables 1 and 2), as shown in Table 1, four types of PEG300, PEG600, PEG4000, and PEG6000 were used. PEG300 and PEG600 correspond to the first polyethylene glycol (indicated by abbreviation PEG1 in Table 2), and PEG4000 and PEG6000 correspond to the second polyethylene glycol (indicated by abbreviation PEG2 in Table 2).

As an antistatic agent, a polyether-polyolefin copolymer which is a polymer type antistatic agent (indicated by an abbreviation ASP1 in Table 2) (trade name Perestat (trademark) 300 manufactured by Sanyo Chemical Co., Ltd., volume resistivity 1 × 10 ⁸ (Ω · cm)) was used.

  As the physical foaming agent, mixed butane composed of 70% by mass of normal butane and 30% by mass of isobutane was used.

  As the cell regulator, a cell regulator masterbatch comprising 20% by mass of talc (trade name High Filler # 12, manufactured by Matsumura Sangyo Co., Ltd.) with respect to 80% by mass of low density polyethylene was used.

  As the foam layer forming extruder, a tandem extruder composed of a first extruder having an inner diameter of 90 mm and a second extruder having an inner diameter of 120 mm was used. As an extruder for forming the surface layer, the first having an inner diameter of 50 mm and L / D = 50 was used. Three extruders were used. Furthermore, the respective outlets of the second extruder and the third extruder were connected to the co-extrusion annular die so that the respective resin melts could be laminated in the co-extrusion annular die.

Examples 1 to 7
(Preparation of resin melt for forming foam layer)
A low-density polyethylene resin and 1.5 parts by mass of an air conditioner master batch with respect to 100 parts by mass of the resin are supplied to the first extruder, melted and kneaded, and the resin melt adjusted to about 200 ° C. It was a thing. Next, 10 parts by mass of mixed butane is injected into 100 parts by mass of the resin and then transferred to a second extruder connected to the downstream side of the first extruder to adjust the extrusion resin temperature to 115 ° C. Thus, a resin melt for forming a foam layer was formed and introduced into the annular die for coextrusion.

(Preparation of resin melt for surface layer formation)
On the other hand, the amount of low density polyethylene resin and polymer type antistatic agent shown in Table 2 and the amount and type of first polyethylene glycol (PEG1) and second polyethylene glycol (PEG2) shown in Table 2 are the third. The mixture was supplied to an extruder and melted and kneaded, and the temperature of the extruded resin was adjusted to 115 ° C. to obtain a resin melt for forming a surface layer, which was introduced into the annular die for coextrusion. The PEG1 was supplied via a submerged pump connected to a third extruder, and PEG2 was added to the third extruder together with the low density polyethylene resin.

  The resin melt for forming the surface layer introduced into the annular die for coextrusion is merged and laminated on the outside and inside of the resin melt for forming the foam layer introduced into the annular die for coextrusion. Extruded into the atmosphere at 130 kg / hr, expanded to a blow-up ratio of 2.8, taken up at a take-up speed of 67 m / min, and further cut open along the extruding direction. Surface layer / foamed layer / surface layer 3 A layered laminated foam sheet (width of about 1400 mm) was produced.

  About the obtained laminated foam sheet, average thickness, apparent density, surface resistivity, water absorption, and glass plate peeling strength were measured as follows. Moreover, the glass plate washability was evaluated as follows. The results are shown in Table 2.

(Average thickness of laminated foam sheet)
The thickness (mm) of the sheet was measured at 1 cm intervals along the width direction over the entire width of the laminated foamed sheet, and the average thickness was calculated by their arithmetic average. The said measurement was performed with respect to three places selected at random of the lamination foam sheet, and the arithmetic average value of the value of the calculated average thickness of the three places was made into the average thickness (mm) of a lamination foam sheet.

(Apparent density of laminated foam sheet)
Five points were selected at random in the extrusion direction of the laminated foamed sheet, and five test pieces were prepared by cutting out each sheet at a sheet width × width of 100 mm over the entire width of the sheet. The calculated mass (kg) by volume (m ³⁾ from outside dimension as to measure each specimen, apparent density (kg / m of each specimen was divided by the mass (kg) of the volume (m ^{3) 3} ) was obtained, and the arithmetic average value of the obtained values was regarded as the apparent density (kg / m ³ ).

(Surface resistivity of laminated foam sheet)
The surface resistivity of the laminated foam sheet was measured according to JIS K 6271 (2008). Specifically, a test piece 100 mm long by 100 mm wide was cut out from the laminated foam sheet, and the test piece was conditioned for 36 hours in an atmosphere at a temperature of 20 ° C. and a relative humidity of 30%. Next, a voltage was applied to both surfaces of each test piece under the condition of an applied voltage of 500V. One minute after starting the voltage application, the surface resistivity of the test piece was measured, and the arithmetic average value thereof (test piece 5 pieces × both sides [n = 10]) was defined as the surface resistivity of the laminated foamed sheet.

(Water absorption rate of laminated foam sheet)
The water absorption rate (mass ppm) of the laminated foam sheet was measured as follows. First, a test piece cut out from a laminated foam sheet to a size of 500 mm wide × 400 mm long is stored for 24 hours under two conditions of temperature 25 ° C., humidity 50% RH, temperature 50 ° C., humidity 80% RH, and then air. The test piece is dried at 180 ° C. in a closed space where the water is blocked, and vaporized substances other than moisture are removed, and moisture is selectively applied to a molecular sieve adsorbent (Molecular sieve 3A °, manufactured by Nacalai Tesque Co., Ltd.). It was made to adsorb | suck and the water absorption (mass ppm) was calculated | required by the following formula | equation (2) from the mass change. Note that RH indicates relative humidity.

However, in the above formula (2), _{M 1} is the mass of the dry test piece before (g), _{M 2} is the mass of the adsorbent after moisture adsorption (g), _{M 3} is moisture adsorption before the adsorbent The mass (g) of is shown.

(Glass plate peel strength)
The peel strength (glass plate peel strength) (N) between the laminated foam sheet and the glass plate was measured as follows. First, 5 test pieces with a size of 60 mm in width and 90 mm in length are cut out from the laminated foamed sheet, the cut out 5 test pieces and 5 glass plates are alternately stacked, and pressure-bonded for 7 days at a load of 25 g / cm ² . I let you. Then, the load when peeling the test piece crimped | bonded to the glass plate at a speed | rate of 100 mm / min was measured, and it was set as peeling strength (N). The peel strength was measured under two conditions: temperature 25 ° C., humidity 50% RH, temperature 50 ° C., humidity 80% RH.

(Glass plate cleanability)
The glass plate cleanability is evaluated by an evaluation test of the glass plate cleanability. The evaluation test of the washability of the glass plate was carried out as follows under two conditions: room temperature storage conditions and high temperature and humidity storage conditions. That is, after the laminated foam sheet was in contact with the glass plate (loading condition: 3.8 g / cm ² ) and stored at 25 ° C. and 50% RH for 24 hours (room temperature storage condition), the glass plate was washed, The contact angle of water at the contact surface with the laminated foam sheet among the surfaces of the glass plate was measured. Moreover, after storing the laminated foam sheet in contact with the glass plate at 50 ° C. and 80% RH for 24 hours (high temperature and high humidity storage conditions), the glass plate is washed, The contact angle of water on the contact surface was measured (measuring atmosphere conditions: temperature 25 ° C., humidity 50% RH).

Based on the measurement result of the contact angle of water on the glass plate after cleaning, the glass plate cleaning property was evaluated according to the following evaluation criteria.
○ (Good glass plate cleanability): Water contact angle after cleaning is less than 10 ° x (Glass plate cleanability is poor): Water contact angle after cleaning is 10 ° or more

Comparative Example 1
A laminated foam sheet was obtained in the same manner as in Example 1 except that only the first polyethylene glycol was used without using the second polyethylene glycol. Using the obtained laminated foam sheet, in the same manner as in Example 1, the average thickness (mm), the apparent density of the foam layer (kg / m ³ ), the surface resistivity (Ω), the water absorption rate (mass ppm), glass The plate peel strength (N) was measured. Moreover, the glass plate washability evaluation test was implemented. The results are shown in Table 2. The obtained laminated foamed sheet had a high water absorption rate under high-temperature and high-humidity conditions, and was inferior in glass detergency.

Comparative Example 2
A laminated foam sheet was obtained in the same manner as in Comparative Example 1 except that the first polyethylene glycol shown in Table 2 was used. Using the obtained laminated foamed sheet, the average thickness, the apparent density of the foamed layer, the surface resistivity, the water absorption, and the glass plate peel strength were measured in the same manner as in Example 1. Moreover, the glass plate washability evaluation test was implemented. The results are shown in Table 2. Similar to Comparative Example 1, the obtained laminated foamed sheet had a high water absorption rate and was inferior in glass detergency under high temperature and high humidity conditions.

Comparative Example 3
A laminated foamed sheet was obtained in the same manner as in Example 1 except that only the second polyethylene glycol was used without using the first polyethylene glycol. Using the obtained laminated foamed sheet, the average thickness, the apparent density of the foamed layer, the surface resistivity, the water absorption, and the glass plate peel strength were measured in the same manner as in Example 1. Moreover, the glass plate washability evaluation test was implemented. The results are shown in Table 2. The obtained laminated foam sheet had a low water absorption, but was inferior in glass cleanability.

Claims (9)

A laminated foam sheet having a polyolefin resin foam layer and a polyolefin resin surface layer laminated and adhered to at least one side of the foam layer,
In the surface layer, polyethylene glycol (PEG) is blended,
The polyethylene glycol (PEG) comprises a first polyethylene glycol (PEG1) that is liquid at 25 ° C. and a second polyethylene glycol (PEG 2) that is solid at 25 ° C.,
The blending amount of the first polyethylene glycol (PEG1) in the surface layer is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer,
The amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass or more with respect to 100 parts by mass of the first polyethylene glycol (PEG1) in the surface layer. Polyolefin resin laminated foam sheet.   2. The polyolefin-based resin laminated foam sheet according to claim 1, wherein the first polyethylene glycol (PEG1) has a number average molecular weight of 100 or more and 800 or less.   The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the second polyethylene glycol (PEG2) has a number average molecular weight of 2000 or more.   The polyolefin resin laminated foam sheet according to any one of claims 1 to 3, wherein the second polyethylene glycol (PEG2) has a freezing point exceeding 50 ° C.   The blending amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the blending amount of the first polyethylene glycol (PEG1) in the surface layer. The polyolefin resin laminated foam sheet according to any one of claims 1 to 4, wherein:   The total amount of the polyethylene glycol (PEG) based on 100 parts by mass of the polyolefin resin constituting the surface layer is 15 parts by mass or less, and the polyolefin type according to any one of claims 1 to 5 Resin laminated foam sheet.   A polymer antistatic agent is blended in the surface layer, and the blending amount of the polymer antistatic agent is 2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. The polyolefin resin laminated foam sheet according to any one of claims 1 to 6, wherein The polyolefin resin constituting the foam layer is low density polyethylene,
The polyolefin resin laminated foam sheet according to any one of claims 1 to 7, wherein the polyolefin resin constituting the surface layer is low density polyethylene.   A slip sheet for a glass plate comprising the polyolefin-based resin laminated foam sheet according to any one of claims 1 to 8.