KR102056950B1 - Multi-layer polyolefin resin foam sheet - Google Patents

Abstract

The present invention is to provide a polyolefin-based resin multilayer foam sheet which is excellent in flexibility and buffering properties, does not damage the surface of the package well, can protect the package from impact, and further greatly improves transition contamination. A polyolefin-based resin multilayer foam sheet having a thickness of 0.2 to 3.0 mm and an apparent density of 15 to 150 kg / m 3 having an antistatic layer on at least one side of the polyolefin resin foam layer, wherein the compounding amount of the polymer type antistatic agent (B) in the antistatic layer ( X) is 5-80 mass%, the compounding quantity (Y) of the filler (C) is 2-25 mass%, and the compounding quantity (Z) of a polyolefin resin (A) is 10 mass% or more (however, of X, Y, Z of The total is 100% by mass), and the ratio (Y / X) of the compounding amount (Y) of the filler (C) to the compounding amount (X) of the polymer type antistatic agent (B) in the antistatic layer is 0.05 to 2.0. It is characterized by.

Description

Polyolefin resin multilayer foam sheet {MULTI-LAYER POLYOLEFIN RESIN FOAM SHEET}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin multilayer foam sheet, and in particular, a polyolefin resin which can be suitably used as an interlayer, a partition material, a packing material, or the like for electronic precision devices such as glass substrates and panels. It relates to a multilayered resin foam sheet.

The polyolefin resin multilayer foam sheet has been used as a material for various cushioning materials and packaging materials in view of being flexible and excellent in cushioning properties and having waterproofness, moisture resistance, and heat resistance. Antistatic foam sheets are widely used as the substrates for glass substrates and panels for dust adhesion prevention and static electricity prevention. Conventionally, when using a foam sheet for the interlayer of a glass substrate and a panel, the surfactant type antistatic agent was used. However, the conventional foam sheet does not exhibit an antistatic effect in an environment with low humidity, and the antistatic agent is transferred to the packaged object. In a relatively high humidity environment, the surface of the packaged object is made sticky. There was a problem causing surface contamination. As described in Patent Literatures 1 and 2, a technique has been developed to exert an excellent antistatic effect and to prevent transfer contamination of the antistatic agent to the packaged object as described in Patent Literatures 1 and 2.

Patent Literature 1 is a polyolefin resin layer containing a polymer type antistatic agent and a resin melt for forming a polyolefin resin foam layer containing a foaming agent so that the polyolefin resin layer containing an antistatic agent becomes a surface. As a method of manufacturing the antistatic foam sheet laminated by co-extrusion, it is disclosed that a volatile plasticizer is added to the melt for forming a resin layer to improve melt elongation of the melt for forming a resin layer.

Patent Literature 2 discloses a foam sheet in which a polyolefin-based resin layer containing a polymer type antistatic agent on at least one side of the polyolefin-based resin foam layer has a basis weight of 0.1 to 20 g / m 2.

Japanese Patent Publication No. 2004-181933 Japanese Patent Publication No. 2005-074771

When a polymer type antistatic agent is used as the antistatic agent in the foam sheet, the transfer contamination to the packaged object is much less than that of the surfactant type antistatic agent, but the transfer contamination to the packaged object occurs in an environment of high temperature and high humidity. There was a case. Moreover, according to the use, further improvement of antistatic performance is required, and it is necessary to increase the addition amount of a polymeric antistatic agent, In this case, further improvement was calculated | required since the transfer contamination to a to-be-packed object also inevitably increases. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyolefin-based resin multi-layer foam sheet which is excellent in flexibility and buffering property, excellent in antistatic performance, and greatly improved in transition contamination to a packaged object. .

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, when the specific filler was mix | blended in the antistatic layer in which the polymeric antistatic agent was mix | blended, the present inventors found out that the migration pollution to the to-be-packaged material of a polymeric antistatic agent drastically improved. The present invention has been completed.

That is, this invention makes the summary of the invention as described in the following (1)-(6).

(1) A polyolefin resin multilayer foam sheet having an apparent density of 15 to 150 kg / m 3 having an antistatic layer containing a polyolefin resin (A) and a polymer antistatic agent (B) on at least one side of the polyolefin resin foam layer. ,

(Iii) Filler (C) is mix | blended with the said antistatic layer,

(Ii) The compounding quantity (X) of the polymeric antistatic agent (B) in the said antistatic layer is 5-80 mass%, the compounding quantity (Y) of the filler (C) is 2-25 mass%, and the compounding quantity of polyolefin resin (A) (Z) is 10 mass% or more (the sum total of X, Y, Z is 100 mass%),

(Iii) The ratio (Y / X) of the compounding amount (Y) of the filler (C) to the compounding amount (X) of the polymer type antistatic agent (B) in the antistatic layer is 0.05 to 2.0, characterized in that the polyolefin type Resin multilayer foam sheet.

(2) The filler (C) is an inorganic filler, The polyolefin resin multilayer foam sheet according to the above (1).

(3) The compounding quantity (X) of the said polymeric antistatic agent (B) is 40-80 mass%, The polyolefin resin multilayer foam sheet of said (1) or (2) characterized by the above-mentioned.

(4) The basis weight (α) of the said antistatic layer is 0.2-10 g / m <2>, The polyolefin resin multilayer foam sheet in any one of said (1)-(3) characterized by the above-mentioned.

(5) Filler (C) has an average primary particle diameter of 2-50 micrometers, The polyolefin resin multilayer foam sheet in any one of said (1)-(4) characterized by the above-mentioned.

(6) The polyolefin resin multilayer foam sheet as described in any one of said (1)-(5) whose filler (C) is at least 1 sort (s) chosen from talc, calcium carbonate, silica, mica, and titanium oxide.

(7) The basis weight (α) of the said antistatic layer is 0.5-8 g / m <2>, The polyolefin resin multilayer foam seat | seat in any one of said (1)-(6) characterized by the above-mentioned.

(8) The ratio (Y / α) of the compounding amount (Y) of the filler (C) to the basis weight (α) of the antistatic layer is 1.6 or more, the polyolefin according to any one of (1) to (7) above. Resin multilayer foam sheet.

In the polyolefin resin multilayer foam sheet of the present invention, a polymer antistatic agent (B) and a filler (C) are compounded in an antistatic layer laminated on at least one side of the polyolefin resin foam layer, and the multilayer foam sheet is used as an interlayer. When used, the transfer of the antistatic agent to the packaged product can be suppressed, so that the surface defect of the packaged object, that is, the occurrence of transfer contamination can be prevented. In addition, even when the compounding quantity of the polymer type antistatic agent (B) is increased in order to use in an environment of high temperature and high humidity and to improve the antistatic performance, the polymer type antistatic agent (B) is transferred to the packaged material and greatly reduces contamination. Can be. In addition, when the foam sheets are stacked and laminated, it is also possible to suppress a phenomenon (blocking phenomenon) in which the polyolefin-based resin multilayer foam sheets are squeezed and hardly peeled off.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of the polyolefin resin multilayer foam sheet of this invention.
It is explanatory drawing which shows an example of the manufacturing method of the polyolefin resin multilayer foam sheet of this invention.

[1] The polyolefin resin multilayer foam sheet of this invention and [2] the manufacturing method of this polyolefin resin multilayer foam sheet are demonstrated below.

[1] polyolefin resin multilayer foam sheets

The polyolefin resin multilayer foam sheet of this invention is 0.2-3.0 mm in thickness which has an antistatic layer containing polyolefin resin (A) and a polymeric antistatic agent (B) on at least one surface of a polyolefin resin foam layer, and an apparent density 15 Filler (C) is mix | blended with the said antistatic layer, The compounding quantity (X) of the polymeric antistatic agent (B) in an antistatic layer is 5-80 mass%, The compounding quantity (Y) of a filler (C) is 2-25 mass%, and the compounding quantity (Z) of a polyolefin resin (A) is 10 mass% or more (however, the sum total of X, Y, Z is 100 mass%), Moreover, the ratio (Y / X) of the compounding quantity (Y) of the filler (C) with respect to the compounding quantity (X) of a polymeric antistatic agent (B) in the said antistatic layer is characterized by being 0.05-2.0.

An example of the polyolefin resin multilayer foam sheet (henceforth a multilayer foam sheet) of this invention is shown by sectional drawing of FIG. The multilayer foam sheet 1 has a polyolefin resin (A) and a polymer type on at least one side of a polyolefin resin foam layer (hereinafter sometimes referred to as a foam layer) using the polyolefin resin (E) as a base resin. It has an antistatic layer (Hereinafter, it may only be called antistatic layer) (3) containing an antistatic agent (B) and a filler (C). Here, although description is centered on having the antistatic layer 3 on both surfaces, it can be set as the structure which has the antistatic layer 3 in the single side | surface of the foam layer 2. As shown in FIG.

(1) antistatic layer

The antistatic layer in this invention contains polyolefin resin (A) and a polymeric antistatic agent (B), the filler (C) is mix | blended, and the compounding quantity (X) of the polymeric antistatic agent (B) in an antistatic layer Is 5-80 mass%, the compounding quantity (Y) of the filler (C) is 2-25 mass%, and the compounding quantity (Z) of polyolefin resin (A) is 10 mass% or more (however, the sum total of X, Y, and Z is 100 mass%), and the ratio (Y / X) of the compounding amount (Y) of the filler (C) to the compounding amount (X) of the polymer type antistatic agent (B) in the antistatic layer is 0.05 to 2.0. The basis weight α of the antistatic layer is 0.2 to 10 g / m 2.

(1-1) Component of Antistatic Layer

(Iii) Polyolefin Resin (A)

The polyolefin resin (A) used for the antistatic layer is a homopolymer having an olefin component of 50 mol% or more, or a copolymer containing 50 mol% or more of the olefin component. As the polyolefin resin (A), the melting point is generally 130 to 170. Polypropylene resin which is C, and polyethylene resin whose melting point is 100-130 degreeC is mentioned generally, Polyethylene resin from a viewpoint of flexibility, such as low surface hardness and excellent surface protection of a to-be-packaged object among these polyolefin resin. Is preferably used. Examples of the polyethylene resins include ethylene polymers such as high density polyethylene, low density polyethylene, and linear low density polyethylene, and mixtures of two or more thereof. Furthermore, melting points of these polyethylene resins are generally 100. The low density polyethylene which is -115 degreeC is more preferable. In addition, melting | fusing point is a value measured based on the heat flux differential scanning calorimeter measurement based on JISK7121 (1987). The DSC curve is obtained by employ | adopting the conditions (but cooling rate is 10 degreeC / min) of the state control (2) of a test piece, and heating up at 10 degreeC / min from 40 degreeC to 200 degreeC. The temperature of the peak of the melting peak in the obtained DSC curve is taken as the melting point. In addition, when two or more melting peaks appear, the temperature of the peak of the largest melting peak is taken as melting | fusing point.

(Ii) a polymeric antistatic agent (B)

The polymer type antistatic agent (B) is distinguished from a low molecular type antistatic agent such as a surfactant, and specifically, a hydrophilic polymer having a volume resistivity of 1 × 10 ⁵ to 1 × 10 ¹¹ Ω · cm (hereinafter, simply hydrophilic Polymers), block polymers of hydrophilic polymer blocks and hydrophobic polymer blocks, and the like. As a hydrophilic polymer, a polyether, a cationic polymer, an anionic polymer, etc. can be illustrated. In addition, a polyolefin, a polyamide, etc. can be illustrated as a hydrophobic polymer block. Moreover, ester bond, amide bond, ether bond etc. can be illustrated as a bond of a hydrophilic polymer block and a hydrophobic polymer block. The surface resistivity of the polymer type antistatic agent available in the market is about 1 * 10 <^6> -1 * 10 <^{10> (} ohm) about.

In order to impart electrostatic acidity to the antistatic layer, and to suppress physical property degradation by adding an antistatic agent in the antistatic layer, it is preferable that the polyolefin resin is copolymerized with the hydrophilic polymer block as the hydrophobic polymer block. Do. As a polymeric antistatic agent, "Pelletstat VL300", "Peltron HS", etc. by Sanyo Chemical Co., Ltd. which are polyether polyolefin block copolymers can be illustrated, for example. Moreover, it is preferable that melting | fusing point of the said polymeric antistatic agent is 125-140 degreeC. It is preferable that the number average molecular weights of the said polymeric antistatic agent are 2000-100000, More preferably, it is 5000-60000, More preferably, it is 10000-400000. In addition, the said number average molecular weight is a number average molecular weight (polystyrene conversion value) converted using the calibration curve obtained from the polystyrene whose molecular weight is known using gel permeation chromatography.

In this invention, the compounding quantity (X) of the polymeric antistatic agent in an antistatic layer is 5-80 mass% (However, the compounding quantity (mass% of the said polyolefin resin (A), polymeric antistatic agent (B), and the said filler) ) Is 100% by mass). When the compounding amount (X) of the polymer type antistatic agent (B) is too small, the antistatic performance is insufficient. On the other hand, when the amount is too high, the physical properties of the antistatic layer and the adhesive strength of the antistatic layer and the foam layer may be deteriorated, resulting in peeling. Moreover, when there is too much compounding quantity X of a polymeric antistatic agent (B), while forming the antistatic layer itself becomes difficult, there exists a possibility that manufacture of a cheap multilayer foam sheet may become difficult. From the said viewpoint, 20 mass% is preferable and, as for the minimum of the compounding quantity (X) of a polymeric antistatic agent (B), 40 mass% is more preferable. On the other hand, 70 mass% is preferable and, as for the upper limit, 60 mass% is more preferable.

In order for the antistatic layer containing a polymer type antistatic agent (B) to exhibit sufficient antistatic performance or stage performance (hereinafter, both may be referred to as antistatic performance), the polymer type antistatic agent in the antistatic layer It is preferable that (B) is disperse | distributed to network form or layer form, and forms a conductive network in resin.

In the antistatic layer, the relationship between the melting point of the polymeric antistatic agent (B) and the extrusion temperature is important in order to disperse the polymeric antistatic agent (B) so that a sufficient conductive network can be formed to exhibit antistatic properties. That is, the melting point of the polymer type antistatic agent (B) at the time of extrusion is in the range where it can flow, and in molten resin for antistatic layer formation, it is necessary to maintain the fluidity necessary to form a sufficient conductive network for achieving antistatic property. It becomes possible.

(Ⅲ) Filler (C)

As the filler (C), any of inorganic fillers and organic fillers generally used as fillers or fillers can be used as long as fine unevenness can be formed on the surface of the antistatic layer. Specific examples of the inorganic filler include general inorganic powders used as fillers such as talc, calcium carbonate, silica, mica and titanium oxide. Examples of the organic filler include polymer fine particles such as styrene resin crosslinked fine particles and acrylic resin crosslinked fine particles. Especially, an inorganic filler is preferable. In particular, talc and calcium carbonate are particularly preferably used because they have a low hardness and do not damage the surface of the package well.

In the multilayer foam sheet of the present invention, the filler (C) is blended with the antistatic layer, whereby a large number of fine irregularities derived from the filler (C) are formed on the surface of the antistatic layer. It is considered that the point contact between the sheet and the packaged object can suppress migration contamination of the antistatic agent as in the prior art, and can suppress the occurrence of surface defects of the packaged object.

As for the said filler (C) in this invention, it is preferable that the average primary particle diameter is 2-50 micrometers, 3-20 micrometers is more preferable at the point which is especially easy to form an antistatic layer, and is easy to form an antistatic layer.

In addition, the said average primary particle diameter is a particle diameter (volume average particle diameter: D50) when a cumulative volume becomes 50% using a laser diffraction type particle size distribution measuring apparatus.

In the present invention, the filler (C) is preferably used in view of the dispersion of the filler (C) by adjusting and using a master batch containing the polyolefin-based resin (A) as a base resin. It is preferable to adjust so that a ratio of a filler may be 10-80 weight% with respect to a base resin, and, as for a masterbatch, it is more preferable to adjust so that it may be 20-70 weight%.

In this invention, the compounding quantity (Y) of the filler (C) in the said antistatic layer is 2-25 mass% (However, the compounding quantity of a polyolefin resin (A), a polymeric antistatic agent (B), and a filler (C) ( The total of mass%) is 100% by mass). When the compounding amount (Y) of the filler (C) is too small, there exists a possibility that the effect which drastically reduces the thing which transfers a polymeric antistatic agent (B) to a to-be-packed object and becomes contaminated may not fully be expressed, On the other hand, when too much, Since elongation of an antistatic layer at the time of manufacture worsens, there exists a possibility that it becomes difficult to form an antistatic layer. From the said viewpoint, 3 mass% is preferable and, as for the minimum of the compounding quantity (Y) of the filler (C), 5 mass% is more preferable. On the other hand, 22 mass% is preferable and, as for the upper limit, 18 mass% is more preferable.

In the antistatic layer, the ratio of the compounding amount (Y) of the filler (C) to the compounding amount (X) of the polymer type antistatic agent (B) is high (Y /) from the viewpoint of particularly excellent antistatic property and further reducing migration contamination (Y / X) is 0.05-2.0 and it is preferable that it is 0.05-1.7.

(Iii) additives

You may add various additives to the said antistatic layer in the range which does not impair the objective of this invention. As various additives, antioxidant, a heat stabilizer, a weathering agent, a ultraviolet absorber, a flame retardant, a filler, an antibacterial agent, etc. are mentioned, for example. The addition amount of these additives is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 3 parts by mass or less based on 100 parts by mass of the polyolefin resin (A) constituting the antistatic layer.

(1-2) Basis weight of antistatic layer (α)

It is preferable that basis weight (alpha) of an antistatic layer is 0.2-10 g / m <2>. Such a very thin antistatic layer can be produced by the coextrusion method described later. When the basis weight α of the antistatic layer is less than the lower limit of the above range, it is difficult to form a resin layer at the time of manufacture even by the coextrusion method, while the basis weight α of the antistatic layer exceeds the upper limit of the above range. In this case, there is a possibility that the light weight and flexibility are insufficient depending on the use of the multilayer foam sheet, and the raw material cost in manufacturing the multilayer foam sheet is also expensive. From the same point of view, the basis weight (α) is more preferably 0.5 to 8 g / m 2, and still more preferably 1 to 7 g / m 2.

The said basis weight (alpha) adjustment is performed by adjusting the discharge amount of the molten resin for antistatic layer formation, and the take-out speed of a multilayer foam sheet. The basis weight α of the antistatic layer can be obtained by the following method. When manufacturing a multilayer foam sheet, the discharge amount x (kg / hr) of the antistatic layer, the width W (m) of the multilayer foam sheet obtained, and the length L per unit time of the multilayer foam sheet obtained in extrusion foam conditions (= multilayer foam When the pulling speed of the sheet (m / hr) can be known, the basis weight (g / m 2) of the antistatic layer can be obtained by the following formula (1).

Basis weight (α) (g / m 2) = [1000x / (L × W)]. (One)

In order to form irregularities on the surface of the multilayer foam sheet, the ratio (Y / α) of the compounding amount (Y) of the filler (C) to the basis weight (α) of the antistatic layer is preferably 1.6 or more, more preferably 1.8 or more. If it is in the said range, fine unevenness | corrugation is formed in the surface of an antistatic layer, and it becomes possible to reduce transition contamination etc. effectively.

(2) polyolefin resin foam layer

The polyolefin resin (E) etc. which comprise the foam layer of the multilayer foam sheet of this invention are described below.

(Iii) Polyolefin Resin (E)

As polyolefin resin (E), the same resin as the polyolefin resin (A) used for the said antistatic layer can be used. Among them, polyethylene-based resins are preferable, and particularly low-density polyethylene is preferably used from the viewpoint of low flexibility, such as low surface hardness and excellent surface protection performance of the package. In view of not damaging the surface of the package, the polyethylene resin preferably has a high flexibility resin having a bending modulus of 600 MPa or less, more preferably 450 MPa or less, and more preferably 300 MPa or less. desirable. The lower limit is about 10 MPa in general. When the bending elastic modulus is too high, the surface of the multilayer foam sheet becomes hard and easily slips with the packaged object, which may easily damage the surface of the packaged object.

(Ii) additives

You may add various additives to a foam layer. As various additives, a nucleating agent, antioxidant, a heat stabilizer, a weathering agent, a ultraviolet absorber, a flame retardant, an inorganic filler, an antibacterial agent, an antishrinkant, etc. are mentioned, for example. In that case, 10 mass parts or less are preferable with respect to 100 mass parts of polyolefin resins (E) which comprise a foam layer, 5 mass parts or less are more preferable, 3 mass parts or less are especially preferable.

(3) polyolefin resin multilayer foam sheet

As shown in FIG. 1, the multilayer foam sheet of this invention has the antistatic layer which consists of a polyolefin resin (A), a polymeric antistatic agent (B), and a filler (C) on at least one surface of a foam layer. Hereinafter, the multilayer foam sheet of this invention is demonstrated.

(Ⅰ) thickness

It is preferable that the thickness of the multilayer foam sheet of this invention is 0.05-3.0 mm, 0.2-3.0 mm is more preferable, 0.3-2.0 mm is more preferable. When using this multilayer foam sheet as a packaging sheet, when there is too thin thickness, there exists a possibility that sufficient buffering property may not be obtained. On the other hand, when thickness is too thick, handling may become complicated in packing a to-be-packed object.

The thickness of the multilayer foam sheet was measured by a micro gauge or the like at intervals of 10 cm in the width direction of the multilayer foam sheet, which was conditioned for 24 hours or more under conditions of a temperature of 23 ± 5 ° C. and a relative humidity of 50%, and the thickness at each measurement point Obtained by arithmetic mean. As such a measuring apparatus, Yamabun Electric Co., Ltd., an offline thickness measuring instrument (model: TOF-4R) etc. can be used, for example.

In addition, adjustment of the thickness of a foam layer and the thickness of an antistatic layer can be adjusted to the said range by adjusting the discharge amount and take-up speed at the time of coextrusion.

(Ii) apparent density

The apparent density of the multilayer foam sheet of this invention is 15-150 kg / m <3>. When the apparent density of this multilayer foam sheet is less than 15 kg / m <3>, there exists a possibility that it may become insufficient strength as a packaging material. From this viewpoint, 18 kg / m <3> or more is preferable and, as for the apparent density of a multilayer foam sheet, 20 kg / m <3> or more is more preferable. On the other hand, when the apparent density of a multilayer foam sheet exceeds 150 kg / m <3>, there exists a possibility that the buffer property of the obtained sheet may fall. From this viewpoint, 100 kg / m <3> or less is preferable and, as for the apparent density of a multilayer foam sheet, 80 kg / m <3> or less is more preferable.

The apparent density of the multilayer foam sheet of this invention is calculated | required by dividing the volume of the multilayer foam sheet calculated | required by the water droplet method, etc. by the mass of the multilayer foam sheet measured beforehand, and converting a unit into (kg / m <3>). In addition, the apparent density of a multilayer foam sheet can be calculated | required by dividing the mass (g / m <2>) per unit area of a foam sheet by said average thickness, and converting it further to (kg / m <3>).

(Iii) surface resistivity

1.0x10 <^7> -1.0 * 10 <^{14> (} ohm) is preferable and, as for the surface resistivity of the multilayer foam sheet of this invention, it is more preferable that it is 1.0 * 10 <^8> -1.0 * 10 <^{11> (} ohm). When the surface resistivity exceeds 1.0 × 10 ¹⁴ Ω, airborne dust and foreign matters may be attracted by static electricity to cause scratches and contaminant adhesions by causing foreign matters to be rolled up during packaging of the packaging material. Moreover, the electrical failure in peeling charging at the time of packing opening may also be caused.

(Iii) Initial high voltage

In a resistance region having an electrical resistivity higher than that of the conductive region, when an electric performance that is not charged at all or hardly charged is required, when 10 kPa is applied to the antistatic layer surface of the multilayer foam sheet of the present invention for 30 seconds 2000 V or less is preferable, 1000 V or less is more preferable, 100 V or less is more preferable, and 0 V is the most preferable. In addition, the measurement of an initial stage big voltage can be measured using a static anneal meter (corona charge system) based on JISL1094A method.

[2] a method for producing a polyolefin resin multilayer foam sheet

As for the multilayer foam sheet of this invention, as illustrated in FIG. 2, for example, polyolefin resin (A) (4), a polymeric antistatic agent (B), and a filler (C) (1) by the 1st extruder 11 ( 5) kneading the polyolefin resin (E) (8) and the physical blowing agent (9) by the antistatic layer-forming molten resin (7) formed by kneading the volatile plasticizer (D) (6) and the second extruder (12). Molten resin for forming polyolefin resin foam layer (hereinafter may be referred to as molten resin for foam layer formation) (10) in each extruder (11, 12) to adjust to an appropriate temperature, and from the die downstream of the extruder It can be obtained by coextrusion.

The appropriate temperature of the molten resin for forming the antistatic layer refers to a temperature at which the foamed layer is easily obtained. Specifically, they are [melting point] or more [melting point +15 degreeC] or less of polyolefin resin (A).

When the antistatic layer-forming molten resin is too lower than the appropriate temperature, the polymer type antistatic agent rapidly becomes high in viscosity and the viscosity becomes very high with respect to the polyolefin resin (A). Therefore, the polymer type antistatic agent is a polyolefin resin (A). There is a fear that it will be difficult to form a conductive network structure.

The production of the multilayer foam sheet 1 by coextrusion is, in the embodiment shown in FIG. 1, an antistatic layer 3 containing a polymeric antistatic agent (B) and a filler (C) as surface layers on both sides of the foam layer 2. ) Is manufactured to be laminated. Although not specifically shown, in addition to the said aspect, the antistatic layer containing a polymeric antistatic agent (B) and a filler (C) may be laminated | stacked on one surface of a foam layer. Or the resin layer which does not contain a polymeric antistatic agent (B) and a filler (C) may be laminated | stacked between the antistatic layer and foam layer containing a polymeric antistatic agent (B) and a filler (C).

(a) Molten resin for antistatic layer formation

A volatile plasticizer (D) is further mix | blended with the molten resin for antistatic layer formation which knead | mixed polyolefin resin (A), a polymeric antistatic agent (B), and a filler (C). By mix | blending a volatile plasticizer (D), the said molten resin is plasticized and the temperature control which reduces the resin temperature of this molten resin to the temperature which does not inhibit foaming of a foam layer is possible, and the extensibility following a foam layer is carried out. Can be given. Such means is particularly effective when the foam layer has a high foaming ratio, and the antistatic layer can be laminated on the foam layer without causing cracks or tears on the surface layer, and the independent foam ratio of the foam layer is increased. It becomes possible to manufacture the multilayer foam sheet which is 20% or more.

Illustrating a preferable volatile plasticizer (D), 1 type (s) or 2 or more types chosen from a C2-C7 aliphatic hydrocarbon, a C1-C4 aliphatic alcohol, or a C2-C8 aliphatic ether can be used as a hydrocarbon type compound. In particular, an aliphatic hydrocarbon having 3 to 6 carbon atoms is preferably used. The use of the hydrocarbon compound is preferable in that it effectively plasticizes the molten resin for forming an antistatic layer. As said C2-C7 aliphatic hydrocarbon, ethane, propane, normal butane, isobutane, normal pentane, isopentane, isohexane, cyclohexane, heptane, etc. are mentioned, Among these, butane is used. It is preferable that isobutane or the mixture of normal butane and isobutane whose isobutane ratio is 30 mol% or more is more preferable, and isobutane is especially preferable.

In the multilayer foam sheet in which the antistatic layer-forming molten resin containing the volatile plasticizer is co-extruded, and the antistatic layer containing the polymer type antistatic agent (B) is laminated as the surface layer of the foam layer, the volatile plasticizer (D) in the antistatic layer (D ) Is almost volatilized by the heat during extrusion at the time of extrusion.

In the method shown in FIG. 2, the volatile plasticizer (D) is added to the antistatic layer formation molten resin of the 2nd extruder 12 which prepares the molten resin for antistatic layer formation, The addition time of the volatile plasticizer (D) It is preferable to add, after disperse | distributing a polymeric antistatic agent (B) and a filler (C) sufficiently in polyolefin resin (A).

In the case of kneading the polyolefin resin (A) and the polymer type antistatic agent (B), the viscosity of the polymer type antistatic agent (B) is reliably dispersed to maintain the conductive network structure by maintaining the viscosity to a certain level. While forming reliably and co-extrusion with a foam layer, the volatile plasticizer (D) is added and the melting temperature (also called resin temperature) of the molten resin for antistatic layer formation is reduced to the temperature which does not inhibit foaming of a foam layer. In addition, extensibility following the foam layer can be imparted. It is effective especially when a foaming layer has high foaming ratio, and can manufacture a reliable multilayer foam sheet.

It is preferable that it is 3-30 mass parts with respect to 100 mass parts of polyolefin resin (A) which comprises an antistatic layer, and, as for the addition amount of a volatile plasticizer (D), it is more preferable that it is 4-25 mass parts. If it is in the said range, the melting temperature of the molten resin for antistatic layer formation can be reduced to the temperature which does not inhibit foaming of foam layer, and the extensibility following the foam layer can be provided.

(b) Molten resin for foam layer formation

The blowing agent used in the above-mentioned molten resin for forming a foam layer may be, for example, aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, isohexane, and cyclohexane, methyl chloride, and ethyl chloride. Organic physical blowing agents, such as hydrogen chloride, etc., and inorganic physical blowing agents, such as nitrogen and a carbon dioxide, are mentioned. The said physical blowing agent can be used in mixture of 2 or more types.

The addition amount of the blowing agent is appropriately adjusted according to the kind of blowing agent and the apparent density of the intended foam layer, but when the organic physical blowing agent such as butane is used as the blowing agent, the addition amount of the organic physical blowing agent constitutes the foaming layer. Preferably it is 3-30 mass parts, More preferably, it is 4-25 mass parts with respect to 100 mass parts of polyolefin resin (E) to make.

A foam regulator is usually added to the molten resin for foam layer formation. As the bubble regulator, any of organic and inorganic ones can be used. Examples of the inorganic bubble regulators include metal borates such as zinc borate, magnesium borate, and borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, sodium bicarbonate, and the like. Examples of the organic bubble regulator include monosodium citrate, sodium 2,2-methylene bis (4,6-tert-butylphenyl) sodium, sodium benzoate, calcium benzoate, aluminum benzoate, sodium stearate and the like.

Moreover, 2 or more types can be mixed and used, for example, which combined citric acid, sodium bicarbonate, the alkali salt of citric acid, and sodium bicarbonate.

The addition amount of the said bubble adjuster becomes like this. Preferably it is 0.5-10 mass parts, More preferably, it is 1-8 mass parts with respect to 100 mass parts of polyolefin resins (E) which comprise a foam layer. Moreover, it is preferable to use a bubble regulator as a master batch.

The method of obtaining a multi-layered foam sheet by the coextrusion method is further described. (A) A method of co-extruding and laminating a sheet from the beginning using a flat die, and (b) Co-extrusion using a cyclic die. Usually, the (i) foam is manufactured, and the method is then cut | disconnected and made into a multilayer foam sheet. Among the above, the method of using the annular die of (b) can suppress the occurrence of wave shapes called corrugations, or can easily produce a wide multi-layer foam sheet having a width of 1000 mm or more. There is an advantage to that.

In the method of coextrusion, the resin layer and the foam layer may be laminated outside the outlet of the annular die or the outlet of the die. Moreover, the said annular die | dye, an extruder, a cylindrical cooling apparatus, the apparatus which cut | disconnects a laminated | multilayer foam normally, etc. can use the well-known thing conventionally used in the field of extrusion foaming.

Example

Hereinafter, an Example and a comparative example demonstrate this invention concretely.

The raw material and evaluation method which were used by the Example are described below.

Next, the multilayer foam sheet of this invention is demonstrated in detail by an Example and a comparative example.

First, the raw material used in the present Example and the comparative example and the evaluation method employ | adopted are described.

(1) raw materials

(1-1) Polyolefin resin (E) for foam layer formation, and polyolefin resin (A) for antistatic layer formation

(a) polyethylene resin LD1

Dow Chemical Co., Ltd., polyethylene resin (trade name: NUC8321, flexural modulus: 205 MPa, MFR (melt flow rate): 2.4 g / 10 min, density 0.922 g / cm 3, melting point: 111 ° C.)

(b) polyethylene resin LD2

Dow Chemical Co., Ltd., polyethylene resin (trade name: NUC8009, flexural modulus of 420 MPa, MFR: 9.0 g / 10 min, density 0.916 g / cm3, melting point: 107 ° C)

(c) polyethylene resin LD3

Manufactured by Sumitomo Chemical Co., Ltd., low density polyethylene resin (trade name: F102, flexural modulus of 205 MPa, MFR: 0.3 g / 10 min, density 0.922 g / cm3, melting point 109 ° C)

In addition, melt viscosity (MFR) of polyethylene-type resin in said (a)-(c) is the value measured employ | adopting the condition code D according to JISK7210 (1999). In the case of adjusting a measurement sample from a foam sheet, the foam sheet is heated in a vacuum oven and degassed as a sample. The defoaming conditions in the vacuum oven at that time make temperature below the melting point of the polyolefin resin which comprises the base resin of a foam sheet also under reduced pressure.

(1-2) Polymer Antistatic Agent

(a) Sanyo Chemical Co., Ltd., Pelletstat 300 (surface resistivity 1 × 10 ⁸ Ω, density 990 g / L, melting point 136 ° C., number average molecular weight 14000)

(b) Sanyo Chemical Co., Ltd., Pelletron HS (surface resistivity 2 × 10 ⁶ Ω, melting point 135 ℃)

(1-3) Filler

(a) talc

Manufactured by Matsumura Industrial Co., Ltd. (Talk (brand name: Hi-filler # 12, whiteness> 92.0, average particle diameter (volume average particle diameter: D50) 3 ~ 4 ㎛)

(b) calcium carbonate

Calcium carbonate (trade name: BF300, average particle diameter (volume average particle diameter: D50) 21.7 μm) manufactured by Shiraishi Calcium Co., Ltd.

In addition, in said (a) and (b), the average particle diameter of a filler will be 50% in cumulative volume using Shimadzu Corporation make, a laser diffraction type particle size distribution measuring apparatus (model: SALD-2100). The particle diameter (volume average particle diameter: D50) at the time was made into the average particle diameter.

(1-4) Bubble adjuster

The bubble adjuster used the bubble adjuster masterbatch which mixes 11.8 mass parts of talc (Matsumura Industries Co., Ltd. product, brand name "high filler # 12"), and 5.9 mass parts of monosodium citrate with respect to 100 mass parts of low density polyethylene. .

(2) evaluation method

(2-1) basis weight of antistatic layer (α)

Basis weight (alpha) of a multilayer foam sheet is performed by adjusting the discharge amount of the molten resin for antistatic layer formation, and the take-up speed of a multilayer foam sheet. The basis weight (α) of the antistatic layer was obtained by the following method. When manufacturing a multilayer foam sheet, the discharge amount x (kg / hr) of the antistatic layer, the width W (m) of the multilayer foam sheet obtained, and the length L per unit time of the multilayer foam sheet obtained in extrusion foam conditions (= multilayer foam When the pulling speed of the sheet (m / hr) can be known, the basis weight (g / m 2) of the antistatic layer was obtained by the following (2) formula.

Basis weight (g / m 2) = [1000x / (L × W)]. (2)

In addition, when the antistatic layer was laminated | stacked on both surfaces of a foaming layer, each basis weight was calculated | required and it was set as the average value.

(2-2) Polyolefin Resin Multilayer Foam Sheet

(Ⅰ) thickness

The thickness of the multilayer foam sheet measured the thickness by a micro gauge at intervals of 10 cm in the width direction of the multilayer foam sheet adjusted for 24 hours or more under conditions of a temperature of 23 ± 5 ° C. and a relative humidity of 50%, and the thickness at each measuring point was measured. It calculated | required by arithmetic mean. As a measuring apparatus, Yamabun Electric Co., Ltd. make and an offline thickness measuring instrument (model: TOF-4R) were used.

(Ii) apparent density

The apparent density of a multilayer foam sheet was calculated | required by dividing the volume of the multilayer foam sheet calculated | required by the water-moulding method, etc. by the mass of the multilayer foam sheet measured previously, and converting a unit into [kg / m <3>].

(Iii) surface resistivity

The surface after 1 minute after applying the test piece (100 mm long x 100 mm x thickness: test piece thickness) cut out three pieces from the multilayer foam sheet by applying at an applied voltage of 500 V according to the method of JIS K 6911 (2006). Resistivity was adopted and the surface resistivity was calculated | required from the average value of the obtained measured value. Takeda Riken Industrial Co., Ltd. make and model: TR8601 were used for the measurement of surface resistivity.

The surface resistivity of the polymer type antistatic agent was kneaded with an extruder or the like to form a molded sheet having a thickness of 2 mm, and the surface resistivity was measured in accordance with the method of JIS K 6911 (2006) in the same manner as the multilayer foam sheet.

(Iii) Initial high voltage

The measurement of the initial large voltage in this invention is cut out in multiple numbers from the multilayer foam sheet by the size of 45 mm x 45 mm (thickness is the thickness of a laminated sheet), and these were made into a test piece for 24 hours in 23 degreeC and 50% RH environment. After adjustment, using a static Ernest meter (manufactured by Shido-do Electrostatic Co., Ltd., TIPE: S-5109), the surface of each antistatic layer was subjected to JIS L 1094 (1988) A method under 23 ° C and 50% RH in accordance with JIS L 1094 (1988) A method. A voltage of kV was applied for 30 seconds, and the initial large voltage when the application was stopped was used as the measured value, and each measured value was averaged to be the initial large voltage. In addition, after each test piece was cut out as a pretreatment, it was wash | cleaned by the ultrasonic cleaner for 10 minutes in the state immersed in 60 degreeC ion-exchange water, and further rinsed with ion-exchange water further, for 1 hour in 60 degreeC oven. After drying, it is adjusted to the above state. When the test piece was immersed in hot water, the metal jig from which oil was removed previously was pressed from the top of the test piece so as not to float from the hot water.

(Iii) Haze value (evaluation of redundancy)

As evaluation of the transferability from a multilayer foam sheet to a to-be-packed object, the haze value of the slide glass which contacted the foam sheet was measured using the turbidimeter (NDH2000) by Nippon Denshoku Kogyo Co., Ltd. based on JISK7136 (2000).

As the pretreatment, the slide glass (76 mm long, 26 mm wide, 0.9 to 1.2 mm thick, manufactured by Matsunami Glass Industry Co., Ltd., product name: S7213) was washed with ethanol, and then the slide glass and the multilayer foam sheet were alternately 10 The sheet was superimposed and pressed by adding a load (weight: 2 kgf, surface load: 50.6 g / cm &lt; 2 &gt;), and then accelerated and contaminated with 24 hr glass in an oven at 60 DEG C and 50 wt% atmosphere.

Ten glass plates which performed the same operation were superimposed, and the contamination state of the glass plate was confirmed by the measurement of the haze which permeated 10 glass plates. The degree of contamination subtracted the haze value before pressing the multilayer foam sheet from the haze value of the glass plate after the multilayer foam sheet was pressed and evaluated as a rise value of the haze value.

In addition, the blank used what laminated 10 slide glass only.

The following evaluation criteria were employ | adopted as the haze rise value (Hz) as the difference of the haze value before and behind a test.

○: less than 5.0 haze rise value

×: haze rising value 5.0 or more

(Iii) blocking resistance

In the blocking resistance test, 10 pieces of sample pieces (size: 40 × 150 mm) cut out from the multilayer foam sheet were applied to each other, and a load was applied thereto, and the blocking resistance was maintained for 7 days at a load of 5.5 g / cm 2 under a 50 ° C environment. Evaluated.

Squeeze holding condition: After hold | maintaining a sample at the load of 5.5 g / cm <2> for 7 days in 50 degreeC environment, the sticking of samples was observed and evaluated.

Evaluation criteria are as follows.

○: No lamination between samples during lamination

X: There is a patch between samples at the time of lamination, and one sheet is impossible to feed

Example 1

As a 2nd extruder for forming an antistatic layer, it uses the tandem extruder which connected the diameter 90mm extruder provided with a foaming agent injection port, and the 120 mm diameter extruder as a 1st extruder for forming a foam layer shown in FIG. The extruder of 50 mm and L / D = 46 (L is length, D is diameter) was used. An annular die having a die lip having a diameter of 94 mm was used for coextrusion of the foam sheet at the extruder outlet of the first extruder and the second extruder.

In order to form a foamed layer, 3 parts by mass of a foam regulator masterbatch was added to 100 parts by mass of low-density polyethylene LD1, fed to a raw material inlet of an extruder having a diameter of 90 mm, heated and kneaded to a molten resin adjusted to about 200 ° C. It was. A physical blowing agent (butane mixed blowing agent of 70% by mass of butane butyrate and 30% by mass of isobutane) was injected into the molten resin so as to 30 parts by mass with respect to 100 parts by mass of the low density polyethylene, and then connected to the downstream side of the extruder having a diameter of 90 mm. It supplied to the extruder of diameter 120mm, it knead | mixed, and obtained the molten resin for foam layer formation of 115 degreeC.

On the other hand, in order to form an antistatic layer, 10 mass% of polymer type antistatic agent and 4 mass% of talc as a filler are mix | blended with respect to 86 mass% of low density polyethylene LD1, and it supplies to the raw material inlet of the 2nd extruder of diameter 50mm, 100 mass of said molten resin mixture was melt-kneaded under heating, and it was made into the molten resin mixture adjusted to about 200 degreeC, and mixed butane (mixture which consists of 70 mass% of normal butanes and 30 mass% of isobutane) as a volatile plasticizer to this molten resin mixture It press-mixed so that it might be 30 mass parts with respect to a part, and after that, resin temperature was adjusted to 118 degreeC and the molten resin for antistatic layer formation was obtained.

The molten resin for foam layer formation and the molten resin for antistatic layer formation obtained above are supplied to a joining die, and are laminated so as to become the molten resin for antistatic layer formation / molten resin for foam layer formation / molten resin for antistatic layer formation in order. Coextruded from the die | dye, the ordinary extruded foam was taken out along the cylinder for cooling, and it cut | disconnected and obtained the multilayer foam sheet of this invention by which the antistatic layer was laminated | stacked and adhere | attached on both surfaces of a foaming layer.

The apparent density and thickness of the obtained multilayer foam sheet, basis weight of an antistatic layer, and the antistatic performance (surface resistivity, initial large voltage), transfer property, and blocking resistance of a multilayer foam sheet were evaluated. The result is put together in Table 2 and shown.

Example 2

In Example 2, the multilayer foam sheet was obtained like Example 1 except having set the filler compounding quantity into 15 mass%.

Example 3

In Example 3, the multilayer foam sheet was obtained like Example 1 except having set the antistatic agent to "Peltron HS" and setting the antistatic agent compounding quantity to 50 mass%.

Example 4

In Example 4, the multilayer foam sheet was obtained like Example 3 except having made the compounding quantity of the filler 10 mass%.

Example 5

Example 5 WHEREIN: Except having made polyolefin resin LD2 and making the apparent density of a multilayer foam sheet 92 kg / m <3>, and the basis weight of an antistatic layer to 5.4 g / m <2>, it carried out similarly to Example 4, A foam sheet was obtained.

Example 6

In Example 6, the multilayer foam sheet of the present invention was obtained in the same manner as in Example 5 except that the filler was calcium carbonate.

Example 7

In Example 7, the present invention was carried out in the same manner as in Example 4 except that the apparent density of the multilayer foam sheet was 46 kg / m 3, the basis weight of the antistatic layer was 0.7 g / m 2, and the thickness of the multilayer foam sheet was 0.34 mm. A multilayer foam sheet was obtained.

Example 8

In Example 8, the multilayer foam sheet of the present invention was obtained in the same manner as in Example 4 except that the blending amount of the filler was 20 parts by mass and the polyolefin resin was LD3.

Example 9

In Example 9, the multilayer foam sheet of this invention was obtained like Example 3 except having set the antistatic agent compounding quantity to 70 mass%, and the compounding quantity of the filler to 6 mass%.

Comparative Example 1

A multilayer foam sheet was obtained in the same manner as in Example 1 except that the filler was not blended. Compared with Example 1, haze value was high and transition pollution increased.

Comparative Example 2

A multilayer foam sheet was obtained in the same manner as in Example 3 except that the amount of the antistatic agent was increased to 50% by mass without blending the filler. Since no filler was blended, it was found that the surface resistivity was superior to that of Example 3 but the evaluation of the transferability was deteriorated.

Comparative Example 3

Except having reduced the compounding quantity of the talc which is a filler to 1 mass part, it carried out similarly to the comparative example 2, and obtained the multilayer foam sheet. Compared with the comparative example 2, although evaluation of the performance was slightly improved, since the filler was insufficient, the performance was poor and the excellent multilayer foam sheet was not obtained.

[Comparative Example 4]

A multilayer foam sheet was obtained in the same manner as in Comparative Example 3 except that the filler compounding amount was 30 mass%. Since the quantity of the filler was too large compared with the comparative example 3, it became difficult to form an antistatic layer.

The used material and evaluation result of this multilayer foam sheet in the said Examples 1-9 and Comparative Examples 1-4 are put together in Table 1 and Table 2, respectively.

1: polyolefin resin multilayer foam sheet
2: polyolefin resin foam layer
3: antistatic layer
4: polyolefin resin
5: polymer type antistatic agent, filler
6: volatile plasticizer
7: molten resin for antistatic layer formation
8: polyolefin resin
9: physical blowing agent
10: molten resin for foam layer formation
11: first extruder
12: second extruder
13: annular die

Claims (8)

It is a polyolefin resin multilayer foam sheet with an apparent density of 15-150 kg / m <3> which has an antistatic layer containing polyolefin resin (A) and a polymeric antistatic agent (B) on at least one side of a polyolefin resin foam layer,
(Iii) Filler (C) is mix | blended with the said antistatic layer, The average primary particle diameter of the said filler (C) is 2-50 micrometers,
(Ii) The compounding quantity (X) of the polymeric antistatic agent (B) in the said antistatic layer is 5-80 mass%, the compounding quantity (Y) of the filler (C) is 10-18 mass%, and the compounding quantity of polyolefin resin (A) (Z) is 10 mass% or more (the sum total of X, Y, Z is 100 mass%), and the basis weight ((alpha)) of the said antistatic layer is 0.2-10 g / m <2>, and the basis weight ((alpha)) of the said antistatic layer The ratio (Y / α) of the compounding amount (Y) of the above filler (C) is 1.6 or more,
(Iv) The ratio (Y / X) of the compounding amount (Y) of the filler (C) to the compounding amount (X) of the polymer type antistatic agent (B) in the antistatic layer is 0.05 to 2.0, characterized in that the polyolefin type Resin multilayer foam sheet. The method of claim 1,
Filler (C) is an inorganic filler, The polyolefin resin multilayer foam sheet. The method of claim 1,
The compounding quantity (X) of the said polymeric antistatic agent (B) is 40-80 mass%, The polyolefin resin multilayer foam sheet characterized by the above-mentioned. The method of claim 1,
The polyolefin resin multilayer foam sheet which said filler (C) is at least 1 sort (s) chosen from talc, calcium carbonate, silica, mica, and titanium oxide. The method of claim 1,
The basis weight (α) of the said antistatic layer is 0.5-8 g / m <2>, The polyolefin resin multilayer foam sheet characterized by the above-mentioned. delete delete delete

Images