TWI779172B - Polyolefin resin laminated foam sheet and spacer paper for glass plate composed of the laminated foam sheet - Google Patents

Abstract

The object of the present invention is to provide a laminated foam sheet and a spacer paper for a glass plate using the laminated foam sheet. The laminated foam sheet is a laminated foam sheet that can be used as a spacer paper for a glass plate. It can also impart excellent washability to packaged objects such as glass plates even under high temperature and high humidity. The solution is a laminated foam sheet, which has a polyolefin resin foam layer and a polyolefin resin surface layer on at least one side of the foam layer; Alcohol (PEG), the aforementioned polyethylene glycol (PEG) is composed of the first polyethylene glycol (PEG1) which is liquid at 25°C and the second polyethylene glycol (PEG2) which is solid at 25°C; With respect to 100 parts by mass of the polyolefin-based resin constituting the aforementioned surface layer, the blending amount of the first polyethylene glycol (PEG1) in the aforementioned surface layer is not less than 0.5 parts by mass and not more than 10 parts by mass; The blending amount of the first polyethylene glycol (PEG1) is 100 parts by mass, and the blending amount of the second polyethylene glycol (PEG2) in the surface layer is more than 3 parts by mass.

Description

Polyolefin-based resin laminated foam sheet and spacer paper for glass plates composed of the laminated foam sheet field of invention

The present invention relates to a polyolefin-based resin laminated foam sheet and a spacer paper for glass plates composed of the laminated foam sheet.

Background of the invention

Polyolefin-based resin laminated foam sheet has excellent flexibility and cushioning properties, and can prevent damage and scratches to the packaged objects. Therefore, the laminated foam sheet has been widely used as packaging materials for home appliances, glassware, pottery, etc. for a long time. Moreover, in recent years, with the development of thin TVs and the expansion of demand, polyolefin-based resin laminated foam sheets have also begun to be widely used as glass for the manufacture or transportation of display panels such as liquid crystal displays, plasma displays, and electroluminescent displays. Boards are used with spacer paper.

Spacer paper for glass plates is a sheet that is sandwiched between glass plates. In general, spacer paper for glass plates is used to prevent glass plates from being damaged or damaged when handling multiple glass plates together, such as storing or transporting glass plates.

When a glass plate is used in a display, etc., the surface of the glass plate is generally washed with water or the like. With the high-definition of displays in recent years, higher quality is required for display glass plates. Therefore, it is now required to pass Washing maintains the surface state of the glass plate in a very clean state. Therefore, for glass spacers, it is gradually required to be one that does not hinder the washability of glass plates and other packaged objects, or that can impart excellent washability to glass plates and other packaged objects.

In response to such a request, for example, Patent Document 1 proposes a polyolefin-based resin laminated foam sheet in which a hydrophilic compound such as polyethylene glycol is contained in the surface layer. When the polyolefin-based resin laminated foam sheet is used as a packaging sheet, the washability of packaged objects packaged by the packaging sheet can be enhanced. Therefore, even if foreign matter or the like is transferred from the packaging sheet to the object to be packaged, the dirt on the surface of the object to be packaged can be easily removed by washing the object to be packaged with water or the like.

prior art literature patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 2010-42556

Summary of the invention

In recent years, there has been an increase in cases where packaged objects such as glass plates are placed in a high-temperature, high-humidity gas environment during storage or transportation. When the conventional polyolefin-based resin laminated foam sheet is used in a high-temperature and high-humidity gas environment, there are cases where the washability imparted to packaged objects such as glass plates is somewhat insufficient.

The object of the present invention is to provide a laminated foam sheet and a spacer paper for glass plates using the laminated foam sheet, which can provide excellent packaging materials such as glass plates even under high temperature and high humidity. Can washing sex.

The gist of the present invention is as follows: (1) A polyolefin-based resin laminated foam sheet, which is a laminated foam sheet with a polyolefin-based resin foam layer and a polyolefin-based resin surface layer, wherein the polyolefin-based resin surface layer The lamination is followed by at least one side of the foam layer; it is characterized in that: the aforementioned surface layer is mixed with polyethylene glycol (PEG), and the aforementioned polyethylene glycol (PEG) is formed from the aforementioned second layer that is liquid at 25°C. 1 polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) which is solid at 25°C; with respect to 100 parts by mass of the polyolefin-based resin constituting the aforementioned surface layer, the aforementioned 1st polyethylene glycol in the aforementioned surface layer The blending amount of polyethylene glycol (PEG1) is not less than 0.5 parts by mass and not more than 10 parts by mass; The blending amount of the aforementioned second polyethylene glycol (PEG2) is more than 3 parts by mass; (2) The polyolefin-based resin laminated foam sheet as described in the above (1), wherein the aforementioned first polyethylene glycol ( PEG1) has a number average molecular weight of not less than 100 and not more than 800; (3) the polyolefin-based resin laminated foam sheet as described in (1) or (2) above, wherein the amount of the second polyethylene glycol (PEG2) The average molecular weight is 2000 or more; (4) The polyolefin-based resin laminate described in any one of the above (1) to (3) Foamed sheet, wherein the freezing point of the second polyethylene glycol (PEG2) is a temperature exceeding 50°C; (5) The polyolefin-based resin layered foam as described in any one of the above (1) to (4) Sheet material, wherein relative to 100 parts by mass of the aforementioned first polyethylene glycol (PEG1) blended in the aforementioned surface layer, the blending amount of the aforementioned second polyethylene glycol (PEG2) in the aforementioned surface layer is 3 More than 100 parts by mass; (6) The polyolefin-based resin laminated foam sheet as described in any one of the above (1) to (5), wherein 100% of the polyolefin-based resin constituting the aforementioned surface layer Parts by mass, the total blending amount of the aforementioned polyethylene glycol (PEG) is less than 15 parts by mass; (7) The polyolefin-based resin laminated foam sheet as described in any one of the above (1) to (6), Wherein the aforementioned surface layer is blended with a polymeric antistatic agent, and relative to 100 mass parts of the polyolefin resin constituting the aforementioned surface layer, the blending amount of the polymeric antistatic agent is 2 mass parts or more and 30 mass parts (8) The polyolefin-based resin laminated foam sheet as described in any one of the above (1) to (7), wherein the polyolefin-based resin constituting the aforementioned foam layer is low-density polyethylene, and constitutes The polyolefin-based resin of the aforementioned surface layer is low-density polyethylene; (9) a spacer paper for a glass plate, which is composed of a polyolefin-based resin laminated foam sheet as described in any one of the above-mentioned (1) to (8). constitute.

The laminated foamed sheet of the present invention is a polyolefin-based resin laminated foamed sheet Even under high temperature and high humidity, it can still give glass plates and other packaged objects excellent washability. Furthermore, the spacer paper for glass plates of the present invention using a laminated foam sheet can impart excellent washability to glass plates even under high temperature and high humidity.

form for carrying out the invention

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

(average thickness of laminated foam sheet)

The average thickness of the laminated foam sheet of the present invention is not particularly limited, and the average thickness of the laminated foam sheet is approximately 0.05 mm to 10 mm. If the average thickness of the laminated foam sheet is within the above range, sufficient cushioning properties can be secured without increasing the volume even if it is used as a spacer paper for glass plates. From the above viewpoint, the lower limit of the average thickness of the laminated foam sheet is preferably 0.07 mm, preferably 0.1 mm, more preferably 0.12 mm. And the upper limit of the average thickness of the laminated foam sheet is preferably 1.0 mm, preferably 0.5 mm, more preferably 0.3 mm.

(Average thickness of specific laminated foam sheet)

The average thickness of the laminated foam sheet in the present invention is specified as the arithmetic mean of all thicknesses (mm) of the laminated foam sheet measured at 1 cm intervals in the width direction over the entire range of the laminated foam sheet. For example, when using an extruder manufacturing method to manufacture a laminated foam sheet, the width direction refers to a direction along the surface of the laminated foam sheet and perpendicular to the extrusion direction of the laminated foam sheet.

(foam layer)

The foamed layer of the laminated foamed sheet of the present invention is a layer formed of a foam using a polyolefin resin as a base resin. The polyolefin-based resin used as the base resin is a resin whose component unit ratio derived from an olefin-based monomer is 50 mol % or more. Examples of polyolefin-based resins include polyethylene-based resins, polypropylene-based resins, and polybutylene-based resins. Among polyolefin-based resins, polyethylene-based resins are particularly preferable from the viewpoint of being more excellent in flexibility.

Examples of polyethylene-based resins 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, or ethylene-1-octene copolymer, or even more 2 or more mixtures etc.

Among these polyethylene-based resins, low-density polyethylene is preferred. In addition, in this specification, low-density polyethylene is a polyethylene-based resin with a density of 890kg/ ^m3 to 935kg/ ^m3 , and preferably a polyethylene-based resin with a density of 900kg/ ^m3 to 930kg/ ^m3 . resin.

Examples of polypropylene-based resins include propylene homopolymers and copolymers of propylene and other olefins. Other olefins that can be copolymerized with propylene include ethylene or 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene α-olefins with 4 to 10 carbons such as ene, 1-heptene, or 3-methyl-1-hexene.

It is also possible to add other resins such as styrene-based resins, or ethylene-propylene rubber to polyolefin-based resins within the range that does not impair the effects of the present invention. Rubber or elastomers such as styrene-butadiene-styrene block copolymers, etc. In this case, when the addition amount of the polyolefin resin constituting the foam layer is 100 parts by mass, the addition amount of other resins or elastomers is preferably 25 parts by mass or less, preferably 10 parts by mass or less, and 5 parts by mass Servings or less are preferred.

Moreover, one type or two or more types of additives may be added to the polyolefin-type resin within the range which does not impair the effect of this invention. Examples of additives include functional additives such as air bubble regulators, nucleating agents, antioxidants, heat stabilizers, weather-resistant agents, ultraviolet absorbers, flame retardants, antibacterial agents, anti-shrinkage agents, and inorganic fillers.

(Apparent density of laminated foam sheet)

The apparent density of the laminated foam sheet of the present invention is preferably not less than 20 kg/m ³ and not more than 450 kg/m ³ . When the apparent density of the laminated foam sheet is within the above range, the laminated foam sheet not only has excellent flexibility, but also has excellent mechanical strength such as shape retention and compressive strength. From the viewpoint of the 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 . Furthermore, from the viewpoint of mechanical strength or elastic strength of the laminated foam sheet, the lower limit of the apparent density is preferably 30kg/m ³ , more preferably 40kg/m ³ , more preferably 50kg/m ³ .

The apparent density of the laminated foam sheet is obtained by cutting out the test piece from the laminated foam sheet, dividing the mass (kg) of the test piece by the volume (m ³ ) obtained from the external dimensions of the test piece value to specify.

(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 surface and back of the foam layer, and is located on the outermost side of the laminated foam sheet. In addition, an intermediate layer may also be formed between the foam layer and the surface layer. Floor. The intermediate layer is, for example, a layer composed of a resin having adhesiveness to both the foam layer and the surface layer.

The thickness of the surface layer is not particularly limited, and can be appropriately determined within a range that does not impair the cushioning properties of the foam layer. For example, the average thickness of the surface layer on one side is preferably smaller than the average thickness of the foam layer. In addition, in the laminated foam sheet having surface layers on both sides, the average thickness of the surface layers on both sides should always be smaller than the average thickness of the foam layer. Also, the average thickness of the surface layer mentioned here can be obtained by the following method. First, after the laminated foam sheet was cut in the width direction to form a cut surface, enlarged photographs were taken at intervals of 1 cm along the width direction of the cut surface over the entire sheet. Then measure the thickness (mm) of the surface layer at each point photographed, and calculate the average thickness obtained by calculating the arithmetic mean of these. After randomly selecting 3 locations on the laminated foam sheet for the above measurement, the arithmetic mean value of the calculated average thickness values of the aforementioned 3 locations is taken as the average thickness of the surface layer.

The surface layer is a layer formed of a resin composition using a polyolefin resin as a base resin. The polyolefin-based resin used as the base resin and other resins or additives blended therein can use the same ones as those described for the foam layer.

For example, the surface layer is preferably a non-foamed layer. The non-foamed layer referred to here refers to a resin layer formed without using a foaming agent or the like for foaming the resin. The above-mentioned non-foamed layer includes a resin layer in which air bubbles are generated accidentally or mixed in during the manufacturing process.

In the laminated foamed sheet of the present invention, the polyolefin resins constituting the foamed layer and the surface layer can use the same resin, and can also be used in the foamed layer and the surface layer. Different resins are used for the surface layer. When the laminated foam sheet is formed of the same type of resin as the foam layer and the surface layer, the adhesiveness between the foam layer and the surface layer will increase. From the standpoint of adhesion between the foam layer and the surface layer, low-density polyethylene is preferably used not only for the foam layer but also for the surface layer.

The basis weight of the surface layer is preferably 0.5 g/m ² or more for one side, preferably 0.7 g/m ² or more, and more preferably 1.0 g/m ² or more. If the basis weight of the surface layer satisfies the above range, the washability of the desired packaged article can be sufficiently improved. From the viewpoint of the washability of the packaged objects, the upper limit of the basis weight of the surface layer is not particularly limited. From the viewpoint of cushioning properties and light weight, the upper limit is preferably 100 g/m ² , preferably 60 g/m ² , more preferably 50 g/m ² .

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

[Mathematical formula 1] Basis weight [g/m ² ]=[1000X/(L×W)]…(1)

(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) mixed in the surface layer is composed of the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2).

Even if the laminated foam sheet of the present invention is placed in a high-temperature and humid gas environment, it can still provide excellent packaging properties such as glass plates. washing sex. The reason why the laminated foam sheet of the present invention can impart excellent washability to packaged objects even under high temperature and high humidity is not clear, but it is believed to be the following two reasons.

First, the laminated foam sheet of the present invention is mixed with the first polyethylene glycol which is liquid at 25°C and the second polyethylene glycol (PEG2) which is solid at 25°C, so that the laminated foam can be reduced. The water absorption rate of the foam sheet. Therefore, we think that even if it is placed in a high-temperature and humid gas environment, dust, dust, etc. will not easily adhere to the surface of the laminated foam sheet. In addition, by lowering the water absorption rate of the laminated foam sheet, it is possible to suppress the organic matter in the atmosphere that is the main cause of fouling, or impurities such as hydrogen ions or calcium ions contained in the water, and the moisture in the air to adhere to the laminated foam sheet. doubts about.

Therefore, when using the laminated foamed sheet of the present invention as a packaging material, the laminated foamed sheet can effectively prevent foreign matter such as dust, dust, the above-mentioned organic matter or the above-mentioned impurities from adhering to the packaged object and contaminating the packaged object. Condition.

Second, we believe that even if the laminated foam sheet of the present invention is placed in a high-temperature and humid gas environment, the first polyethylene glycol (PEG1) can more evenly overflow from the surface layer to the packaged object.

That is, the first polyethylene glycol (PEG1) contained in the surface layer overflows from the surface layer and adheres to the surface of the packaged object, so the dirt on the surface can be easily washed off when the packaged object is washed. However, the first polyethylene glycol (PEG1), which is liquid at 25° C., tends to become liquid droplets on the surface layer, resulting in unevenness. Therefore, when spilled, it is difficult for the first polyethylene glycol (PEG1) to move evenly to the packaged object. In contrast, the laminated foam sheet of the present invention can disperse the first polyethylene glycol (PEG1) evenly in the presence of the second polyethylene glycol (PEG2). on the surface layer. Therefore, we believe that the laminated foam sheet of the present invention can make the first polyethylene glycol (PEG1) of the hydrophilic compound move more easily and evenly from the surface layer to the packaged object. As a result, when the packaged goods are washed, uneven washing of the packaged goods can be suppressed, and good washability can be provided.

Based on the above reasons, we believe that the laminated foam sheet of the present invention can impart excellent washability to the packaged objects even under high temperature and high humidity.

(Amount of polyethylene glycol blended)

The total blending 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. If the total blending amount of polyethylene glycol (PEG) in the surface layer is within the above range, even in a high-temperature and high-humidity gas environment, it can still give glass plates and other packaged objects more excellent washability laminated foam sheet. Based on the above viewpoint, the upper limit of the blending amount of polyethylene glycol (PEG) is preferably 12 parts by mass, more preferably 10 parts by mass. Furthermore, the lower limit of the blending amount of polyethylene glycol (PEG) is preferably 1.0 parts by mass exceeding 0.5 parts by mass.

(1st polyethylene glycol (PEG1))

The first polyethylene glycol (PEG1) in the surface layer is polyethylene glycol that is liquid at 25°C. Since the first polyethylene glycol (PEG1) is liquid at 25° C., the first polyethylene glycol (PEG1) is more likely to overflow from the surface layer, thereby imparting excellent washability to the packaged article. Based on the above viewpoint, the first polyethylene glycol (PEG1) is preferably a liquid at 23°C, more preferably a liquid at 10°C, and especially preferably a 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 preferably not less than 100 and not more than 800. If the number average molecular weight of the first polyethylene glycol (PEG1) is within the above range, the first polyethylene glycol (PEG1) will easily overflow from the surface layer, and excellent washability can be imparted to the packaged article. Based on the above viewpoint, the lower limit of the number average molecular weight of the first polyethylene glycol (PEG1) is preferably 150, more preferably 200. Moreover, the upper limit of the number average molecular weight of the first polyethylene glycol (PEG1) is preferably 700, more preferably 600.

(specific method for number average molecular weight)

The number average molecular weight of the first polyethylene glycol (PEG1) can be obtained by a known method calculated from the hydroxyl value.

(the blending amount of the first polyethylene glycol (PEG1))

The compounding quantity of the said 1st polyethylene glycol (PEG1) in a surface layer is 0.5 mass part or more and 10 mass parts or less with respect to 100 mass parts of polyolefin resins which comprise the said surface layer. If the ratio of the blending amount of the first polyethylene glycol (PEG1) is within the above-mentioned range, the laminated foam sheet can impart more excellent washability to the packaged object. Based on the above viewpoint, the lower limit of the blending amount of the first polyethylene glycol (PEG1) is preferably 1.0 parts by mass, more preferably 2 parts by mass. In addition, the upper limit of the blending amount of the first polyethylene glycol (PEG1) is preferably 8 parts by mass, more preferably 6 parts by mass.

The first polyethylene glycol (PEG1) can be obtained from the market. In the present invention, commercially available products that can be used as the first polyethylene glycol (PEG1) include "Polyethylene Glycol 300" manufactured by FUJIFILM Wako Pure Chemical Co., and the like.

(2nd polyethylene glycol (PEG2))

The second polyethylene glycol (PEG2) in the surface layer is polyethylene glycol that is solid at 25°C. The second polyethylene glycol (PEG2), which is solid at 25°C, is mixed with the first polyethylene glycol (PEG1), which is liquid at 25°C, in the surface layer of the laminated foam sheet to form a laminated foam sheet. Even if the foam sheet is placed in a high-temperature and humid gas environment, it can still give glass plates and other packaged objects better washability.

(Number average molecular weight of the second polyethylene glycol (PEG2))

From the point of view of further improving the washability of packaged objects such as glass plates under high temperature and high humidity, the number average molecular weight of the aforementioned second polyethylene glycol (PEG2) is preferably 2000 or more, and more preferably 2500 or more, More than 3000 is better. The upper limit of the number average molecular weight of the second polyethylene glycol (PEG2) is approximately 20,000.

(specific method for number average molecular weight)

The number average molecular weight of the second polyethylene glycol (PEG2) can be obtained by the same method as the number average molecular weight of the aforementioned first polyethylene glycol (PEG1).

(Freezing point of the second polyethylene glycol (PEG2))

In addition, from the viewpoint of further improving the washability of packaged objects such as glass plates under high temperature and high humidity, the freezing point of the second polyethylene glycol (PEG2) is preferably at a temperature exceeding 50°C, and at least 52°C Preferably, more preferably above 55°C. The upper limit of the freezing point of the second polyethylene glycol (PEG2) is approximately 65°C.

(Specific method for freezing point)

The freezing point of the second polyethylene glycol (PEG2) can be obtained by the method described in JIS K 0065 (1992), etc.

(the blending amount of the second polyethylene glycol (PEG2))

The compounding quantity of the 2nd polyethylene glycol (PEG2) in the surface layer is 3 mass parts or more with respect to 100 mass parts of the compounding quantity of the 1st polyethylene glycol (PEG1) in the said surface layer. If the blending amount of the second polyethylene glycol (PEG2) is too small, when it is placed in a high-temperature and humid gas environment, it may not be able to give sufficient washability to packaged objects such as glass plates. Based on the above point of view, relative to 100 parts by mass of the blending amount of the first polyethylene glycol (PEG1) in the aforementioned surface layer, the blending amount of the second polyethylene glycol (PEG2) in the surface layer is preferably 5 mass parts servings or more.

The upper limit of the blending 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, compared with the first polyethylene glycol (PEG2) in the above-mentioned surface layer The compounding quantity of ethylene glycol (PEG1) is 100 mass parts, Preferably it is 100 mass parts or less.

In particular, from the viewpoint of imparting washability and manufacturing stability, the total blending amount of polyethylene glycol (PEG) in the surface layer is 15 parts by mass or less; and relative to 100 parts by mass of the first polyethylene glycol (PEG1) blended in the surface layer, the blending amount of the second polyethylene glycol (PEG2) in the surface layer is 3 parts by mass More than 100 mass parts is preferable.

The second polyethylene glycol (PEG2) can be obtained from the market. In the present invention, examples of commercially available products that can be used as the second polyethylene glycol (PEG2) include "Polyethylene Glycol 6000" manufactured by FUJIFILM Wako Pure Chemical Co., and the like.

In addition, the laminated foam sheet of the present invention contains the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) in the surface layer. So, namely Even in a high-temperature and humid gas environment, the peel strength of the laminated foam sheet relative to the packaged object is still small. Therefore, for example, when lifting and taking out the packaged object, it is possible to prevent the packaging material made of the laminated foam sheet from following the packaged object and being lifted up together with the packaged object. As a result, good workability can be achieved when using the packaged object.

(antistatic agent)

The laminated foam sheet of the present invention can be blended with an antistatic agent in the surface layer within the range that does not impair the effect of the object of the present invention. Antistatic agent should use polymer antistatic agent. Polymer antistatic agents include polyether-polyolefin copolymers, ionomer resins, and the like. Examples of polyether-polyolefin copolymers are those sold under the trade names of Sanyo Chemical Industry Co., Ltd. "Pelestat (trademark) VL300", "Pelestat (trademark) 300", "Pelestat HC250", "Pelestat (trademark) )HS”, “Pelectron PVH”, “Pelectron LMP”, etc. Examples of ionomer resins include those sold under the trade names "Entira (trademark) SD100" and "Entira MK400" manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.

(surface resistivity)

The surface resistivity of the laminated foam sheet of the present invention is preferably not less than 1×10 ⁸ Ω and not more than 1×10 ¹⁴ Ω. If the surface resistivity of the laminated foam sheet is within the above range, the laminated foam sheet can exhibit sufficient antistatic properties. Based on the above point of view, the surface resistivity of the laminated foam sheet is preferably not more than 5×10 ¹³ Ω, more preferably not more than 1×10 ¹³ Ω.

The surface resistivity of the laminated foam sheet can be measured in accordance with JIS K 6271 (2008). That is, the surface that will contain the laminated foam sheet The test piece cut into the predetermined size after layering is placed in an air environment with a temperature of 20°C and a relative humidity of 30% for 36 hours to adjust the state of the test piece. Then, using the condition-conditioned test piece, in accordance with JIS K 6271 (2008), start applying a voltage of 500 V for 1 minute, and obtain the surface part of the surface layer of the laminated foam sheet in the test piece. Surface resistivity, and use it as the surface resistivity of laminated foam sheet.

The blending amount of the aforementioned high molecular weight antistatic agent is preferably not less than 2 parts by mass and not more than 30 parts by mass with respect to 100 parts by mass of the polyolefin resin constituting the surface layer. If the blending amount of the antistatic agent is within the above range, the laminated foam sheet will have excellent antistatic performance. From the above point of view, with respect to 100 parts by mass of the aforementioned polyolefin-based resin constituting the surface layer, the blending amount of the antistatic agent is preferably not less than 3 parts by mass and not more than 25 parts by mass, more preferably not less than 5 parts by mass and not more than 20 parts by mass .

(Manufacturing method of laminated foam sheet)

The laminated foam sheet of the present invention can be produced, for example, by a co-extrusion method using a ring die. First, additives such as a polyolefin-based resin for foam layer formation and, if necessary, a cell regulator are supplied to an extruder for foam layer formation. Next, the mixture containing the polyolefin resin and the additive is heated and kneaded, and a physical blowing agent is further pressed in, and then the mixture and the physical blowing agent are kneaded to obtain a resin melt for forming a foam layer. On the other hand, additives such as polyolefin-based resin for surface layer formation, polyethylene glycol, and optionally an antistatic agent are supplied to the extruder for surface layer formation, and heated and kneaded to obtain a melted resin for surface layer formation. things. Then, the resin melt for foam layer formation and the resin melt for surface layer formation are introduced into the ring for co-extrusion. Shaped mold, co-extruded foaming. Thereby, a cylindrical laminated foam body with a surface layer laminated on the foam layer is formed, and the cylindrical laminated foam body is pulled and cut while increasing its diameter to obtain a laminated foam sheet.

In the method for producing a laminated foam sheet, in order to obtain a resin melt for forming a surface layer, the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) can be added as polyethylene glycol. At this time, the method of adding the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) is not particularly limited. For example, the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) may be simultaneously supplied to the extruder for forming the surface layer, or may be separately supplied to the extruder for forming the surface layer. Furthermore, the second polyethylene glycol (PEG2) may be supplied to the extruder for forming the surface layer together with the polyolefin-based resin, or may be heated in advance to make it liquid, and then supplied to the extruder for forming the surface layer using a submerged pump or the like. extruder. The first polyethylene glycol (PEG1) may also be supplied to the extruder for surface layer formation using a submerged pump. In addition, the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG2) can also be kneaded with the polyolefin resin for surface layer formation in advance to form a masterbatch, and then supplied to the extruder for surface layer formation. machine.

As the cell regulator used when forming the foam layer, either an organic cell regulator or an inorganic cell regulator can be used. Examples of the inorganic air cell regulator include zinc borate, magnesium borate, borate metal salts such as borax, sodium chloride, aluminum hydroxide, talc, zeolite, silicon dioxide, calcium carbonate, and heavy calcium carbonate. In addition, examples of organic foam regulators include 2,2-methylenebis(4,6-tert-butylphenyl)sodium phosphate, sodium benzoate, calcium benzoate, aluminum benzoate, and sodium stearate. In addition, the composition of citric acid and sodium bicarbonate, or the alkali metal salt of citric acid (alkali salt) and sodium bicarbonate, etc. can also be used as bubbles. Regulators are used. In addition, each of these illustrated air cell regulators may be used in combination of two or more.

In addition, talc is preferably used as the cell regulator in view of the ease of adjustment of the cell diameter of the foam layer. In addition, with respect to 100 parts by mass of the polyolefin-based resin constituting the foamed layer, it is preferable to add the cell regulator in the range of approximately 0.1 parts by mass to 3 parts by mass, and more preferably 0.2 parts by mass to 2 parts by mass the following.

The physical foaming agent can be used without particular limitation as long as it can be used for manufacturing the foam layer of a laminated foam sheet. As the physical foaming agent, an inorganic physical foaming agent or an organic physical foaming agent can be used. Examples of inorganic physical blowing agents include oxygen, nitrogen, carbon dioxide, and air. Organic physical foaming agents can include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, isohexane or cyclohexane; Hydrocarbons; 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,3,3,3-tetrafluoropropene, or 1-chloro-3,3,3-trifluoropropene Fluorinated hydrocarbons; ethers such as dimethyl ether or methyl ethyl ether; or alcohols such as methanol or ethanol, etc. In addition, the said physical foaming agent can also mix and use 2 or more types.

Among these physical foaming agents, n-butane, isobutane or a mixture thereof is preferably used as the physical foaming agent from the standpoint of stably implementing the co-extrusion method and stably obtaining a good foam layer.

(spacer paper for glass plate)

The laminated foam sheet of the present invention can be used as a spacer paper for glass plates. Spacer paper for glass plates can be sandwiched between glass plates to prevent glass plates from being damaged due to contact with each other. The glass using the spacer paper for the glass plate As a glass plate, the glass plate for displays, such as a liquid crystal display, is mentioned. The glass plates for displays are usually washed individually with water or the like after removing the spacer paper for glass plates sandwiched between the glass plates. At this time, if there is dust, dust, organic matter, etc. on the surface of the glass plate, it will be difficult to wash the dust, dust, organic matter, etc. with water. In this regard, if the spacer paper for glass plates is composed of the laminated foam sheet of the present invention, polyethylene glycol will smoothly move from the laminated foam sheet to the surface of the glass plate, and the individual glass plates will be washed with water or the like. When cleaning, it can easily wash off the dust, dust, organic matter, etc. attached to the surface of the glass plate.

In addition, the spacer paper for glass plates may be placed in a high-temperature and high-humidity gas environment in a state of being sandwiched between glass plates. In this regard, if the spacer paper for glass plates is composed of the laminated foamed sheet of the present invention, the water absorption of the laminated foamed sheet can be lowered, so even if it is placed in a high-temperature and humid gas environment, the laminated foamed sheet The surface is also not easy to attach dust, dust, organic matter, etc. Therefore, it can effectively suppress that dust, dust, organic matter, etc. adhere to the glass plate via the laminated foam sheet and contaminate the glass plate.

Furthermore, the laminated foam sheet of the present invention has a small peeling strength with the packaged object even in a high-temperature and high-humidity gas environment as described above. Therefore, for example, when picking up and taking out a plate-shaped packaged object, the laminated foam sheet does not follow the packaged object and is lifted together with the packaged object, and workability is good. This point also supports that the laminated foam sheet of the present invention can be suitably used as a spacer paper for glass plates.

In addition, the laminated foam sheet of the present invention may not only have a surface layer in one side layer of the foam layer, but may also have a surface layer in both side layers. When using a laminated foam sheet as a spacer paper for glass plates, the two areas of the foam layer should be Layers have surface layers. When the spacer paper for glass plates with surface layers on both sides of the foam layer is sandwiched between the glass plates, the two glass plates that are in contact with the spacer paper for glass plates can reduce contamination and improve washability.

The present invention will be described in detail below based on examples. However, this invention is not limited to an Example.

Example

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

Polyethylene glycol (shown by the abbreviation of PEG in Table 1 and Table 2) as shown in Table 1, 4 kinds of PEG300, PEG600, PEG4000, and PEG6000 were used. PEG300 and PEG600 correspond to the first polyethylene glycol (represented by the abbreviation of PEG1 in Table 2), and PEG4000 and PEG6000 correspond to the second polyethylene glycol (represented by the abbreviation of PEG2 in Table 2).

The antistatic agent is a polyether-polyolefin copolymer (abbreviated as ASP1 in Table 2) using a polymer antistatic agent (manufactured by Sanyo Chemical Industry Co., Ltd., trade name Pelestat (trademark) 300, volume resistivity 1 ×10 ⁸ (Ω‧cm)).

As a physical foaming agent, mixed butane composed of 70% by mass of n-butane and 30% by mass of isobutane was used.

As the foam regulator, a foam regulator masterbatch was used, which was obtained by mixing 20% by mass of talc (manufactured by Matsumura Sangyo Co., Ltd., trade name HI-FILLER #12) with 80% by mass of low-density polyethylene. become.

The extruder for forming the foam layer is a tandem extruder consisting of a first extruder with an inner diameter of 90mm and a second extruder with an inner diameter of 120mm, and an extruder with an inner diameter of 50mm for the surface layer And the third extrusion machine with L/D=50. In addition, each outlet of the second extruder and the third extruder is connected to the ring die for co-extrusion, so that each resin melt described later can be laminated in the ring die for co-extrusion. In addition, the laminated foam sheet in each example and each comparative example is designed so that the average thickness of the foam layer is 0.1464mm, and the average thickness of the surface layers on both sides is 0.0018mm respectively.

Examples 1 to 7

(preparation of resin melt for foam layer formation)

A low-density polyethylene resin and 1.5 parts by mass of a cell regulator masterbatch based on 100 parts by mass of the resin were supplied to the first extruder, melted and kneaded to prepare a resin melt adjusted to about 200°C. Next, 10 parts by mass of mixed butane relative to 100 parts by mass of the resin was injected, and then transferred to the second extruder connected to the downstream side of the first extruder, and the temperature of the extruded resin was adjusted to 115° C. After the resin melt for forming a foam layer is prepared, it is introduced into the above-mentioned ring die for coextrusion.

(preparation of resin melt for surface layer formation)

On the other hand, the low-density polyethylene resin in the amount shown in Table 2 and the polymer type antistatic agent and the first polyethylene glycol (PEG1) and the second polyethylene glycol (PEG1) and the second polyethylene glycol in the amount and type shown in Table 2 were mixed. Alcohol (PEG2) was supplied to the third extruder to be melted and kneaded, and the temperature of the extruded resin was adjusted to 115° C. to prepare a surface layer forming resin melt, which was then introduced into the ring die for co-extrusion. In addition, the aforementioned PEG1 is supplied through a liquid pump connected to the third extruder, and PEG2 is added to the third extruder together with the low-density polyethylene resin.

After the resin melt for forming the surface layer introduced into the ring die for co-extrusion is merged and laminated on the outside and inside of the resin melt for forming the foam layer introduced into the ring die for co-extrusion, the above-mentioned The annular die was extruded into the air at a discharge rate of 130 kg/hr to form a cylindrical laminated foam. At this time, the diameter length of the cylindrical built-up foam was enlarged so that the blow-up ratio (blow-up ratio) became 2.8, and at the same time, it was wound up at a winding speed of 67 m/min and cut along the extrusion direction. In this way, a laminated foam sheet (about 1400 mm in width) consisting of three layers of surface layer/foam layer/surface layer was produced. In addition, the basis weight of the surface layer (one side) of the laminated foam sheet produced under the above conditions was 1.7 g/m ² .

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

(average thickness of laminated foam sheet)

The thickness (mm) of the sheet was measured at intervals of 1 cm along the width direction over the entire range of the laminated foam sheet, and the average thickness was calculated from the arithmetic mean thereof. After randomly selecting 3 places on the laminated foam sheet to carry out the aforementioned measurements, the The arithmetic mean of the values of the calculated average thickness at the aforementioned 3 locations is the average thickness (mm) of the laminated foam sheet.

(Apparent density of laminated foam sheet)

Five locations were randomly selected in the extrusion direction of the laminated foam sheet, and five test pieces were prepared by cutting out the sheet width x width 100 mm from the entire range of the sheet for each location. Then measure the mass (kg) of each test piece and obtain the volume (m ³ ) from the external dimensions, then divide the above mass (kg) by the above volume (m ³ ) to obtain the apparent density (kg/m3) of each test piece ³ ), and the arithmetic mean of the obtained values is the apparent density (kg/m ³ ).

(Surface resistivity of laminated foam sheet)

The surface resistivity of the laminated foam sheet was measured in accordance with JIS K 6271 (2008). Specifically, after randomly cutting a test piece with a length of 100 mm x a width of 100 mm from the laminated foam sheet, it was placed in an air environment with a temperature of 20°C and a relative humidity of 30% for 36 hours to carry out the state adjustment of the test piece. Next, a voltage was applied to both surfaces of each test piece under the condition of applying a voltage of 500V. After 1 minute of applying the voltage, measure the surface resistivity of the test piece, and take the arithmetic mean value (5 pieces of test piece x both sides [n=10]) as the surface resistivity (Ω) of the laminated foam sheet .

(Water absorption rate of laminated foam sheet)

The water absorption (ppm by mass) of the laminated foam sheet was measured in the following manner. First, cut out 5 test pieces with a width of 500mm x length of 400mm from the laminated foam sheet, and store them for 24 hours under two conditions of temperature 25°C and humidity 50%RH and temperature 50°C and humidity 80%RH. Then, dry the test piece at 180°C in an air-blocked airtight space to remove vaporization other than moisture. After that, water was selectively adsorbed on a molecular sieve adsorbent (manufactured by Nacalai Tesque Inc., molecular sieve 3A°), and the water absorption (mass ppm) was obtained from the mass change according to the following formula (2). And the arithmetic mean value is used as the water absorption rate (ppm) of the laminated foam sheet. In addition, RH represents relative humidity.

[Mathematical formula 2] Water absorption (mass ppm)=[(M ₂ -M ₃ )/M ₁ ]×10 ⁶ ...(2)

However, in the above formula ( ₂ ), M1 represents the mass (g) of the test piece before drying, _M2 represents the mass (g) _of the adsorbent after water absorption, and M3 represents the mass (g) of the adsorbent before water absorption.

(Peel strength of glass plate)

The peel strength between the laminated foam sheet and the glass plate (glass plate peel strength) (N) was measured in the following manner. First, after cutting out 5 test pieces with a size of 60 mm wide x 90 mm long from the laminated foam sheet, the 5 test pieces cut out are overlapped with 5 glass plates and crimped with a load of 25 g/ ^cm2 for 7 sky. Then, the load when the test piece bonded to the glass plate was peeled at a speed of 100 mm/min was measured, and this was taken as the peel strength (N). The arithmetic mean values of the peel strength (N) values when each test piece was peeled were obtained and listed in Table 2. The measurement of the peeling strength was carried out under two conditions of temperature 25°C and humidity 50%RH and temperature 50°C and humidity 80%RH.

(glass plate washability)

The washability of the glass plate is evaluated by the evaluation test of the washability of the glass plate. The evaluation test of the washability of the glass plate was carried out in the following manner under two conditions of normal temperature storage condition and high temperature and high humidity storage condition. That is, after storing the laminated foam sheet at a temperature of 25° C. and a humidity of 50% RH for 24 hours (normal temperature storage conditions) in a state where the laminated foam sheet is in contact with a glass plate (load condition: 3.8 g/cm ² ), the laminated foam sheet is After peeling off the foam sheet, the glass plate was washed, and the water contact angle on the contact surface between the surface of the glass plate and the laminated foam sheet was measured. And, after storing the laminated foam sheet and the glass plate at a temperature of 50°C and a humidity of 80%RH for 24 hours (high-temperature and high-humidity storage conditions), the laminated foam sheet was peeled off and the glass plate was washed. , and measure the water contact angle between the surface of the glass plate and the contact surface of the laminated foam sheet (measurement environment conditions: temperature 25°C, humidity 50%RH). In addition, the measurement of the water contact angle was carried out using a contact angle meter DM500R (manufactured by Kyowa Interface Science Co., Ltd.), and the measurement was carried out after 1.5 μL of the liquid was deposited and 5 seconds after the liquid was deposited.

According to the measurement results of the water contact angle on the glass plate after washing, the washability of the glass plate was evaluated according to the following evaluation criteria.

○ (good washability of glass plate): the water contact angle after washing is less than 10°

× (Poor washability of glass plate): The water contact angle after washing is 10° or more

Comparative example 1

A laminated foam sheet was produced in the same manner as in Example 1 except that the second polyethylene glycol (PEG2) was not used and only the first polyethylene glycol (PEG1) was used. Using the obtained laminated foam sheet, the average thickness (mm), apparent density (kg/m ³ ) of the foam layer, surface resistivity (Ω), water absorption (mass ppm), glass Plate Peel Strength (N). And carry out the evaluation test of the washability of the glass plate. The results are listed in Table 2. The obtained laminated foam sheet has high water absorption rate and poor glass washability under high temperature and high humidity conditions.

Comparative example 2

In addition to using what is shown in Table 2 as the first polyethylene glycol (PEG1) to In addition, in the same manner as in Comparative Example 1, a laminated foam sheet was produced. Using the obtained laminated foam sheet, the average thickness, the apparent density of the foam layer, the surface resistivity, the water absorption, and the glass plate peel strength were measured in the same manner as in Example 1. And carry out the evaluation test of the washability of the glass plate. The results are listed in Table 2. As in Comparative Example 1, the obtained laminated foam sheet had high water absorption under high-temperature and high-humidity conditions, and was inferior in glass washability.

Comparative example 3

A laminated foam sheet was produced in the same manner as in Example 1, except that only the second polyethylene glycol (PEG2) was used instead of the first polyethylene glycol (PEG1). Using the obtained laminated foam sheet, the average thickness, the apparent density of the foam layer, the surface resistivity, the water absorption, and the glass plate peel strength were measured in the same manner as in Example 1. And carry out the evaluation test of the washability of the glass plate. The results are listed in Table 2. The obtained laminated foamed sheet had low water absorption, but was very poor in glass washability.

[Table 2]

(none)

Claims (9)

A polyolefin-based resin laminated foam sheet, which is a laminated foamed sheet having a polyolefin-based resin foam layer and a polyolefin-based resin surface layer, wherein the polyolefin-based resin surface laminate layer is followed by the foam layer At least one side; it is characterized in that: the aforementioned surface layer is blended with polyethylene glycol (PEG), and the aforementioned polyethylene glycol (PEG) is composed of the first polyethylene glycol (PEG1) which is liquid at 25°C and It is composed of the second polyethylene glycol (PEG2) which is solid at 25°C; with respect to 100 parts by mass of the polyolefin-based resin constituting the aforementioned surface layer, the blending of the aforementioned first polyethylene glycol (PEG1) in the aforementioned surface layer The blending amount is not less than 0.5 parts by mass and not more than 10 parts by mass; with respect to 100 parts by mass of the blending amount of the first polyethylene glycol (PEG1) in the aforementioned surface layer, the aforementioned second polyethylene glycol (PEG1) in the aforementioned surface layer The compounding quantity of (PEG2) is 3 mass parts or more. The polyolefin-based resin laminated foam sheet according to claim 1, wherein the number average molecular weight of the first polyethylene glycol (PEG1) is 100 to 800. The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the number average molecular weight of the second polyethylene glycol (PEG2) is 2000 or more. The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the freezing point of the second polyethylene glycol (PEG2) is a temperature exceeding 50°C. The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the aforementioned first polyethylene glycol (PEG1) in the aforementioned surface layer is blended in an amount of 100 parts by mass, and the aforementioned first polyethylene glycol (PEG1) in the aforementioned surface layer is 2 The compounding quantity of polyethylene glycol (PEG2) is 3 mass parts or more and 100 mass parts or less. The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the total blending amount of the aforementioned polyethylene glycol (PEG) is 15 parts by mass relative to 100 parts by mass of the polyolefin-based resin constituting the aforementioned surface layer the following. The polyolefin-based resin laminated foamed sheet as claimed in claim 1 or 2, wherein a high-molecular antistatic agent is blended in the aforementioned surface layer, and relative to 100 parts by mass of the polyolefin-based resin constituting the aforementioned surface layer, the high The blending amount of the molecular type antistatic agent is not less than 2 parts by mass and not more than 30 parts by mass. The polyolefin-based resin laminated foam sheet according to claim 1 or 2, wherein the polyolefin-based resin constituting the foam layer is low-density polyethylene, and the polyolefin-based resin constituting the surface layer is low-density polyethylene. A spacer paper for a glass plate is composed of the polyolefin-based resin laminated foam sheet according to any one of Claims 1 to 8.