JPWO2018131601A1 - Polypropylene-based foam sheet and article - Google Patents

Abstract

The polypropylene-based foam sheet (100) of the present invention contains a polypropylene-based resin and an inorganic filler, and the density of the polypropylene-based foam sheet (100) is 0.5 g / cm 3 or more and 1.0 g / cm 3 or less. Then, when the total thickness of the polypropylene-based foam sheet (100) is T [mm], 0.1 T [toward the center (102) from the surface (101) in the thickness direction of the polypropylene-based foam sheet (100). The content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the surface area (103) up to mm] is W1, and from the center (102) to the surface (101) ± 0.1 T [mm] When the content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the central region (104) is W2, the relationship of W1> W2 is satisfied.

Description

  The present invention relates to polypropylene-based foam sheets and articles.

  Woodboards such as hardboards and medium density fiberboards are used as building materials, furniture, partitions, heat insulators, packaging materials, etc. because they are lightweight and have excellent mechanical properties.

  As a technique regarding such a wooden board, the thing as described in patent document 1 (Unexamined-Japanese-Patent No. 2014-151599) and patent document 2 (Unexamined-Japanese-Patent No. 2010-64306) is mentioned, for example.

  Patent Document 1 discloses a woody board formed by bonding wood chips or wood fibers with an adhesive and forming the wood fiber, and containing a soft cell-removed bamboo fiber obtained by removing a soft cell from a bamboo fiber obtained by crushing bamboo. A wood board to be characterized is described.

  Further, Patent Document 2 is a wood board obtained by heat-pressing a wood material together with an adhesive, and the wood board is a fine powder of sodium sulfite having an average particle diameter of 40 μm or more and 180 μm or less. A wood board is described which is characterized in that it comprises from 0.1% by weight to 30% by weight with respect to the dry weight.

JP, 2014-151599, A JP, 2010-64306, A

  From the viewpoint of global environmental protection, it is expected that deforestation will be suppressed and it will be difficult to obtain timber resources, so alternatives to wood boards are required.

  The present invention has been made in view of the above circumstances, and provides a polypropylene-based foam sheet which is excellent in balance of lightness and mechanical properties and is suitable as a substitute for wood boards.

  The present inventors diligently studied in order to realize a wood board substitute excellent in performance balance of lightness and mechanical properties. As a result, the present inventors have found that a polypropylene-based foam sheet satisfying the specific relationship with the content of the inorganic filler in the thickness direction of the sheet is excellent in the balance of lightness and mechanical properties.

  That is, according to the present invention, a polypropylene-based foam sheet shown below is provided.

[1]
A polypropylene foam sheet comprising a polypropylene resin and an inorganic filler, wherein
The density of the polypropylene-based foam sheet is 0.5 g / cm ³ or more and 1.0 g / cm ³ or less,
When the total thickness of the polypropylene-based foam sheet is T [mm], in the thickness direction of the polypropylene-based foam sheet,
The content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the surface region from the surface toward the center to 0.1 T [mm] is W ₁ ,
When the content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the central region from the center to the surface to ± 0.1 T [mm] is W ₂ ,
Polypropylene-based foam sheet satisfying the relationship of W ₁ > W ₂
[2]
In the polypropylene-based foam sheet described in the above [1],
The polypropylene-type foam sheet in which the said inorganic filler contains 1 type, or 2 or more types selected from a talc, mica, and a silica.
[3]
In the polypropylene-based foam sheet according to the above [2],
The polypropylene-type foam sheet in which the said inorganic filler contains a talc.
[4]
In the polypropylene foam sheet according to any one of the above [1] to [3],
The difference (W ₁ -W ₂ ) between the content (W ₁ ) of the inorganic filler in the surface region and the content (W ₂ ) of the inorganic filler in the central region is 5 parts by weight or more and 90 parts by weight or less Polypropylene-based foam sheet.
[5]
In the polypropylene-based foam sheet according to any one of the above [1] to [4],
The content (W ₁ ) of the inorganic filler in the surface area is 5 parts by mass or more and 90 parts by mass or less when the total amount of the polypropylene resin and the inorganic filler contained in the surface area is 100 parts by mass. There is a polypropylene-based foam sheet.
[6]
In the polypropylene-based foam sheet according to any one of the above [1] to [5],
The content (W ₂ ) of the inorganic filler in the central region is 0 parts by mass or more and 50 parts by mass or less when the total amount of the polypropylene resin and the inorganic filler contained in the central region is 100 parts by mass. There is a polypropylene-based foam sheet.
[7]
In the polypropylene-based foam sheet according to any one of the above [1] to [6],
The polypropylene-based foam sheet in which the flexural modulus of elasticity of the polypropylene-based foam sheet measured at 23 ° C. and 50% RH is 1 GPa or more.
[8]
In the polypropylene foam sheet according to any one of the above [1] to [7],
The total content of the polypropylene-based resin and the inorganic filler in the polypropylene-based foam sheet is 50% by mass or more and 100% by mass or less based on 100% by mass of the entire polypropylene-based foam sheet Sheet.
[9]
In the polypropylene foam sheet according to any one of the above [1] to [8],
The polypropylene-type foam sheet whose thickness of the said polypropylene-type foam sheet is 1 mm-30 mm.
[10]
In the polypropylene-based foam sheet according to any one of the above [1] to [9],
A polypropylene-based foamed layer containing the above-mentioned polypropylene-based resin and the above-mentioned inorganic filler,
A first non-foamable resin layer provided on one surface of the polypropylene-based foam layer and containing the polypropylene-based resin and the inorganic filler;
A second non-foamable resin layer provided on the other surface of the polypropylene foam layer and containing the polypropylene resin and the inorganic filler;
A polypropylene based foam sheet comprising:
[11]
In the polypropylene-based foam sheet according to the above [10],
The polypropylene-based foam sheet in which the thickness of each of the first non-foamable resin layer and the second non-foamable resin layer is 0.1 mm or more and 5 mm or less.
[12]
In the polypropylene-based foam sheet according to the above [10] or [11],
The ratio of the thickness of the first non-foamable resin layer to the thickness of the entire polypropylene-based foam sheet is 0.1 or more and 0.4 or less,
The polypropylene-based foam sheet wherein the ratio of the thickness of the second non-foamable resin layer to the thickness of the entire polypropylene-based foam sheet is 0.1 or more and 0.4 or less.
[13]
In the polypropylene-based foam sheet according to any one of the above [10] to [12],
A polypropylene-based foam sheet having the same composition and the same thickness as the first non-foamable resin layer and the second non-foamable resin layer.
[14]
In the polypropylene foam sheet according to any one of the above [1] to [13],
Polypropylene-based foam sheet used as a substitute for wood board.
[15]
An article comprising the polypropylene foam sheet according to at least one of the above [1] to [14] as a component.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in the performance balance of lightness and mechanical characteristics, and can implement | achieve the polypropylene-type foam sheet | seat suitable as a substitute of a wood board.

  The objects described above, and other objects, features and advantages will become more apparent from the preferred embodiments described below and the following drawings associated therewith.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the polypropylene foam seat of embodiment which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the polypropylene foam seat of embodiment which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, "AB" of a numerical range represents A or more and B or less unless there is particular notice.

<Polypropylene-based foam sheet>
1 and 2 are cross-sectional views schematically showing an example of the structure of a polypropylene-based foam sheet 100 according to an embodiment of the present invention.
The polypropylene-based foam sheet 100 according to the present embodiment contains a polypropylene-based resin and an inorganic filler, and the density of the polypropylene-based foam sheet 100 is 0.5 g / cm ³ or more and 1.0 g / cm ³ or less. When the total thickness of the polypropylene foam sheet 100 is T [mm], the surface area 103 from the surface 101 to the center 102 in the thickness direction of the polypropylene foam sheet 100 is 0.1 T [mm]. Assuming that the content of the inorganic filler relative to the total amount of the polypropylene-based resin and the inorganic filler is W ₁ , the total amount of the polypropylene-based resin and the inorganic filler in the central region 104 from the center 102 toward the surface 101 ± 0.1 T [mm] the content of the inorganic filler when the _{W 2,} satisfying the relationship of W 1> _{W 2} against.

As described above, since it is expected that deforestation will be suppressed and it will become difficult to obtain timber resources from the viewpoint of global environmental protection, alternatives to wooden boards are required.
Therefore, the present inventors diligently studied in order to realize a wood board substitute excellent in the lightness and the performance balance of mechanical characteristics. As a result, the present inventors have found that a polypropylene-based foam sheet satisfying the specific relationship with the content of the inorganic filler in the thickness direction of the sheet is excellent in the balance of lightness and mechanical properties.
That is, according to the polypropylene-based foam sheet 100 according to the present embodiment, the content W ₁ of the inorganic filler in the surface region 103 and the content W ₂ of the inorganic filler in the central region 104 satisfy the relationship of W ₁ > W ₂ Thus, the balance between the lightness and mechanical properties of the polypropylene-based foam sheet 100 can be improved. That is, by relatively increasing the content W ₁ of the inorganic filler in the surface area 103 of the polypropylene foam sheet 100, the mechanical properties of the polypropylene foam sheet 100 can be further improved, and the center of the polypropylene foam sheet 100 By relatively lowering the content W ₂ of the inorganic filler in the region 104, the polypropylene foam sheet 100 can be made lighter.
As mentioned above, according to this embodiment, it is excellent in the performance balance of lightness and mechanical characteristics, and can realize the polypropylene system foaming sheet suitable as a substitute of a wood board.

  Moreover, since the polypropylene-based foam sheet 100 uses a plastic polypropylene-based resin, it is superior in water resistance to wood boards, and is excellent even when it is wet with water or left in a high humidity environment for a long time Mechanical properties can be maintained. Further, the polypropylene-based foam sheet 100 is less likely to generate chips like a wood board, and is excellent in handleability.

In the polypropylene-based foam sheet 100, the difference (W ₁ -W ₂ ) between the content (W ₁ ) of the inorganic filler in the surface region 103 and the content (W ₂ ) of the inorganic filler in the central region 104 From the viewpoint of further improving the performance balance of the physical properties, the amount is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and 25 parts by mass or more Still more preferably, the content is 35 parts by mass or more, still more preferably 45 parts by mass or more, and particularly preferably 55 parts by mass or more.
In the polypropylene foam sheet 100, the (W ₁ -W ₂ ) content is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and still more preferably 80 parts by mass or less It is particularly preferable that the amount is 75 parts by mass or less.
By setting the above (W ₁ -W ₂ ) to the above-mentioned upper limit value or less, it is possible to realize the polypropylene-based foam sheet 100 which is more excellent in appearance.

When the content (W ₁ ) of the inorganic filler in the surface area 103 of the polypropylene foam sheet 100 is 100 parts by mass of the total amount of the polypropylene resin and the inorganic filler contained in the surface area 103, the lightness and mechanical properties are obtained. From the viewpoint of further improving the performance balance of the characteristics, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and 25 parts by mass or more Is even more preferable, 35 parts by mass or more is even more preferable, 45 parts by mass or more is even more preferable, and 55 parts by mass or more is particularly preferable.
In addition, by setting the content (W ₁ ) of the inorganic filler to the above lower limit or more, mechanical properties such as bending properties and tensile properties of the polypropylene-based foam sheet 100, heat resistance, moisture resistance, dimensional stability, etc. are improved. It can be done.
In addition, in the polypropylene-based foam sheet 100, the content (W ₁ ) of the inorganic filler in the surface region 103 is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and 80 parts by mass or less It is more preferable that the amount be 75 parts by mass or less.
By the content of the inorganic filler (W ₁₎ and more than the above upper limit, it is possible to realize an excellent polypropylene foam sheet 100 by appearance.

When the content (W ₂ ) of the inorganic filler in the central region 104 in the polypropylene foam sheet 100 is 100 parts by mass of the total amount of the polypropylene resin and the inorganic filler contained in the central region 104, the lightness and mechanical From the viewpoint of further improving the performance balance of the characteristics, it is preferably 0 parts by mass or more and 50 parts by mass or less, more preferably 0 parts by mass or more and 40 parts by mass or less, and is 0 parts by mass or more and 30 parts by mass or less Is more preferably 0 to 20 parts by mass, still more preferably 0 to 10 parts by mass, still more preferably 0 to 5 parts by mass preferable.

The density of the polypropylene-based foamed sheet 100 is a 1.0 g / cm ³ or less, preferably less than 1.0 g / cm ^3, more preferably 0.95 g / cm ³ or less, 0.90 g / cm ³ or less is particularly preferred. When the density is less than or equal to the above upper limit value, a lighter polypropylene foam sheet 100 can be obtained. Moreover, since a polypropylene-type foam sheet can float in water as a density is below the said upper limit value or less than a component, it becomes easier to separate a component, and recyclability can be improved.
Moreover, the density of the polypropylene-based foam sheet 100 is 0.5 g / cm ³ or more, preferably 0.6 g / cm ³ or more, more preferably 0.65 g / cm ³ or more, and further 0.70 g / cm ³ or more. preferable. When the density is at least the above lower limit, mechanical properties such as bending properties and tensile properties of the polypropylene-based foam sheet 100 can be further improved.
The density of the polypropylene-based foam sheet 100 can be controlled within the above range by appropriately controlling, for example, the type and blending amount of the polypropylene-based resin, the inorganic filler, etc., the expansion ratio of the polypropylene-based foam sheet 100, etc. it can.

1 GPa or more is preferable, 2 GPa or more is more preferable, 3 GPa or more is more preferable, 4 GPa or more is still more preferable, and 4.5 GPa is the flexural modulus of the polypropylene-based foam sheet 100 measured in an environment of 23 ° C. and 50% RH. The above is even more preferable, and 5 GPa or more is particularly preferable.
By setting the bending elastic modulus to the above lower limit or more, the rigidity of the polypropylene foam sheet 100 can be further improved, and as a result, the deformation of the polypropylene foam sheet 100 against external stress can be suppressed, or the polypropylene foam sheet can be The scratch resistance, heat resistance, dimensional stability, etc. of 100 can be improved.
Moreover, 10 GPa or less is preferable and, as for the bending elastic modulus of the polypropylene foam sheet 100, 9 GPa or less is more preferable.
By setting the bending elastic modulus to the above upper limit value or less, the balance between the deformation resistance to external stress of the polypropylene foam sheet 100 and the toughness can be made better.
Here, the flexural modulus of the polypropylene-based foam sheet 100 can be measured by a three-point bending test. For example, referring to the flexural strength test described in JIS A5905, under an environment of 23 ° C. and 50% RH, test specimen thickness t: 3 mm, specimen width b: 50 mm, specimen length: 150 mm, span interval The deflection amount Y [mm] with respect to the test load F [N] is measured under the condition of the distance L: 100 mm and the bending speed: 50 mm / min. The gradient ΔF / ΔY of the initial linear portion in the obtained load-deflection diagram is determined, and the bending elastic modulus: E [GPa] is determined from the following equation (1).
E = {L ³ / (4b · t ³ )} · (ΔF / ΔY) (1)
One point is measured in each of the MD direction and the TD direction, and the average value thereof can be adopted as a bending elastic modulus.
The flexural modulus of the polypropylene foam sheet 100 is controlled within the above range by appropriately controlling, for example, the type and amount of the polypropylene resin, the inorganic filler, etc., and the expansion ratio of the polypropylene foam sheet 100, etc. be able to.

  The total content of the polypropylene-based resin and the inorganic filler in the polypropylene-based foam sheet 100 is preferably 50% by mass to 100% by mass, more preferably 70% by mass, based on 100% by mass of the entire polypropylene-based foam sheet 100. % By mass to 100% by mass, more preferably 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass. Thereby, it is possible to obtain the polypropylene-based foam sheet 100 which is more excellent in balance of lightness, mechanical properties, recyclability, handleability, appearance, moldability, moisture resistance and the like.

In addition, as shown in FIG. 2, the polypropylene foam sheet 100 is provided on one surface of a polypropylene foam layer 105 containing a polypropylene resin and an inorganic filler, and the polypropylene foam layer 105, and a polypropylene resin and A first non-foamable resin layer 110 containing an inorganic filler, and a second non-foamable resin layer 120 provided on the other surface of the polypropylene-based foam layer 105 and containing a polypropylene resin and an inorganic filler Is preferred.
With such a layer configuration, mechanical properties such as bending properties and tensile properties of the polypropylene-based foam sheet 100, heat resistance, moisture resistance, dimensional stability, and the like can be improved.
Furthermore, it becomes easier to adjust the content W ₁ and W ₂ of the inorganic filler in the polypropylene foam sheet 100, and the polypropylene foam sheet 100 satisfying the relationship of W ₁ > W ₂ can be obtained more easily. .

The content of the inorganic filler in the first non-foamable resin layer 110 and the second non-foamable resin layer 120 is the polypropylene resin contained in the first non-foamable resin layer 110 and the second non-foamable resin layer 120, and When the total amount of the inorganic filler is 100 parts by mass, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, from the viewpoint of further improving the performance balance of lightness and mechanical properties. 15 parts by mass or more, more preferably 25 parts by mass or more, still more preferably 35 parts by mass or more, still more preferably 45 parts by mass or more, 55 parts by mass It is particularly preferred that the content is at least parts.
In addition, by setting the content of the inorganic filler in the first non-foamable resin layer 110 and the second non-foamable resin layer 120 to the above lower limit value or more, the machine such as the bending characteristics and tensile characteristics of the polypropylene-based foam sheet 100 Characteristics, heat resistance, moisture resistance, dimensional stability, etc. can be improved.
In addition, the content of the inorganic filler in the first non-foamable resin layer 110 and the second non-foamable resin layer 120 is a polypropylene-based material contained in the first non-foamable resin layer 110 and the second non-foamable resin layer 120. When the total amount of the resin and the inorganic filler is 100 parts by mass, it is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, still more preferably 80 parts by mass or less, and 75 parts by mass It is particularly preferred that it is not more than part.
By setting the content of the inorganic filler in the first non-foamable resin layer 110 and the second non-foamable resin layer 120 to the above upper limit value or less, it is possible to realize the polypropylene-based foam sheet 100 more excellent in appearance.

  In the polypropylene-based foam sheet 100, it is preferable that the first non-foamable resin layer 110 and the second non-foamable resin layer 120 have the same composition and the same thickness. By doing this, the Young's modulus and the linear expansion coefficient of the first non-foamable resin layer 110 and the second non-foamable resin layer 120 can be made equal to each other, so that warping due to thermal stress or moisture absorption, etc. It is possible to more effectively suppress the dimensional change due to the deformation of the polypropylene foam sheet 100, and further to obtain the polypropylene foam sheet 100 further excellent in mechanical properties such as bending properties and tensile properties and heat resistance.

  Although the thickness of the polypropylene-based foam sheet 100 is not particularly limited, it is, for example, 1 mm or more and 30 mm or less, preferably 1 mm or more and 20 mm or less, and more preferably 1.5 mm or more and 12 mm or less. When the thickness of the polypropylene-based foam sheet 100 is in this range, the balance of lightness, mechanical properties, recyclability, handleability, appearance, moldability and the like is more excellent.

  Moreover, when the polypropylene-based foam sheet 100 includes the first non-foamable resin layer 110 and the second non-foamable resin layer 120, the thickness of the first non-foamable resin layer 110 and the second non-foamable resin layer 120 is Although not particularly limited, they are each preferably 0.1 mm or more and 5 mm or less, and more preferably 0.1 mm or more and 3 mm or less.

In the case of including the first non-foamable resin layer 110 and the second non-foamable resin layer 120 in the polypropylene-based foam sheet 100, the thickness of the first non-foamable resin layer 110 relative to the thickness of the entire polypropylene-based foam sheet 100. The ratio is preferably 0.1 or more and 0.4 or less, more preferably 0.1 or more and 0.3 or less, and still more preferably 0.1 or more and 0.2 or less.
In addition, the ratio of the thickness of the second non-foaming resin layer 120 to the thickness of the entire polypropylene-based foam sheet 100 is preferably 0.1 or more and 0.4 or less, and more preferably 0.1 or more and 0.3 or less. And more preferably 0.1 or more and 0.2 or less.

  Hereinafter, each component which comprises the polypropylene foam sheet 100 is demonstrated.

<Polypropylene-based resin>
The polypropylene-based foam sheet 100 according to the present embodiment contains a polypropylene-based resin as an essential component.
As a polypropylene resin which concerns on this embodiment, a propylene homopolymer, a copolymer of propylene and ethylene, or a C4-C20 alpha-olefin, etc. are mentioned, for example. Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene etc. are mentioned. Among these, ethylene or an α-olefin having 4 to 10 carbon atoms is preferable, and ethylene is more preferable. These α-olefins may form a random copolymer with propylene and may form a block copolymer. The content of the structural unit derived from these α-olefins is preferably 5 mol% or less, more preferably 2 mol% or less, in the polypropylene resin. The polypropylene resins in the polypropylene foam sheet 100 may be used alone or in combination of two or more.
Among these, a propylene homopolymer is preferable as the polypropylene-based resin from the viewpoint of obtaining the polypropylene-based foam sheet 100 having higher rigidity.

  The polypropylene resin according to the present embodiment can be manufactured by various methods. For example, it can manufacture using well-known catalysts, such as a Ziegler natta type | system | group catalyst and a metallocene type catalyst.

  The melt flow rate (MFR) of the polypropylene-based resin according to the present embodiment measured according to ASTM D1238 under conditions of 230 ° C. and a 2.16 kg load is preferably 0.5 g from the viewpoint of flowability and moldability. It is preferably 10 g / 10 min or less, more preferably 10 g / 10 min or more, and more preferably 1 g / 10 min or more, in order to further stabilize moldability and to further suppress foam cell breakage. Or less, more preferably 7 g / 10 minutes or less.

The polypropylene resin according to the present embodiment has high melt tension and melt elongation, and from the viewpoint of excellent moldability, the Z average molecular weight (Mz) / weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is Preferably it is 7 or more and 20 or less, more preferably 10 or more and 20 or less.
A polypropylene resin having an Mz / Mw value in the above range exhibits a wide molecular weight distribution and contains a large amount of high molecular weight components, so it has high melt tension and melt elongation, and is excellent in moldability including foaming. Therefore, by using a polypropylene-based resin having an Mz / Mw value in the above range, the foamability of the polypropylene-based foam sheet 100 can be improved, and even if the inorganic filler is highly filled, the foam cells can be uniformly formed. It is possible to make the properties better and to further suppress the perforation and sheet breakage of the polypropylene-based foam sheet 100, and as a result, it is possible to realize the polypropylene-based foam sheet 100 more excellent in appearance.
The content of the polypropylene resin having an Mz / Mw value in the above range is preferably 50% by mass or more, more preferably 60% based on 100% by mass of the entire polypropylene resin contained in the polypropylene foam sheet 100. It is mass% or more.

<Inorganic filler>
The polypropylene-based foam sheet 100 according to the present embodiment contains an inorganic filler as an essential component.
As the inorganic filler, for example, talc, mica, clay, wollastonite, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, kaolin, perlite, calcium sulfate, barium sulfate, potassium titanate, barium sulfate, calcium sulfite, Calcium silicate, silica, diatomaceous earth, alumina, titanium oxide, glass fiber, glass bead, glass balloon, milled fiber, montmorillonite, bentonite, guffite, aluminum powder, glass flake, carbon fiber, carbon flake, carbon balun, carbon Beads, carbon milled fibers, carbon black, graphite, carbon nanotubes, ceramic fibers, molybdenum sulfide, aramid particles, aramid fibers, boron fibers, silicon carbide fibers, polyethylene Ren fibers, polypropylene fibers, polyester fibers, polyamide fibers, polyarylate fibers, various whiskers, wood flour, pulp, cellulose nanofibers, chaff, paper sludge, and the like. These can be used singly or in combination of two or more.
Among these, as an inorganic filler, one or two or more selected from talc, mica and silica from the viewpoint of obtaining a polypropylene-based foam sheet 100 excellent in lightness, mechanical properties, recyclability, handleability and appearance Is preferred. Among these, talc and mica are preferable from the viewpoint of low cost, and talc is more preferable from the viewpoint of compatibility with a polypropylene resin, foamability, moldability, coloring property, low price, safety and the like.

  In addition, the inorganic filler may be used as it is without treatment, and in order to improve the interfacial adhesion to the polypropylene resin and improve the dispersibility to the polypropylene resin, a silane coupling agent, a titanium coupling agent, The surface may be treated with a surfactant or the like for use.

<Other ingredients>
The polypropylene-based foam sheet 100 according to the present embodiment may be, as necessary, a heat stabilizer, an antioxidant, an ultraviolet absorber, a pigment, an antistatic agent, an anti-copper agent, a flame retardant, a neutralizing agent, a foaming agent, Plasticizers, nucleating agents, antifoaming agents, crosslinking agents, weathering stabilizers, light stabilizers, antiaging agents, fatty acid metal salts, softeners, dispersing agents, coloring agents, lubricants, natural oils, synthetic oils, waxes, etc. You may mix | blend an additive.

<Method for producing polypropylene-based foam sheet>
The polypropylene-based foam sheet 100 has, for example, a polypropylene-based resin composition including an inorganic filler and a polypropylene-based resin on both sides of a polypropylene-based foam layer obtained by foaming a polypropylene-based resin composition containing a polypropylene-based resin into a sheet. It can obtain by forming the resin layer comprised with a thing.
The molding apparatus and the molding conditions are not particularly limited, and conventionally known molding apparatuses and molding conditions can be adopted.

(Method of preparing polypropylene-based resin composition)
The polypropylene resin composition according to the present embodiment mixes, melts and kneads the respective components with a dry blend, tumbler mixer, Banbury mixer, single screw extruder, twin screw extruder, high speed twin screw extruder, hot roll, etc. Can be prepared by

(Molding method of polypropylene based foam sheet)
The forming method of the polypropylene-based foam sheet 100 according to the present embodiment can be performed by, for example, a known method using a multilayer extruder, a lamination molding machine, or the like. The polypropylene-based foam sheet 100 is, for example, a multilayer of a polypropylene-based resin composition for forming the polypropylene-based foam layer 105 and a polypropylene-based resin composition for forming a resin layer containing an inorganic filler and a polypropylene-based resin. It can be obtained by multilayer extrusion of a T-die tip into a sheet from the main extruder of the extruder and the hopper of the secondary extruder.
Moreover, the polypropylene-based foam sheet 100 can be obtained by separately molding the polypropylene-based foam layer 105, the inorganic filler, and the resin layer containing the polypropylene-based resin, laminating the layers, and performing heat molding. In this case, a thermal adhesive layer made of, for example, a low melting point polyolefin resin may be interposed between the polypropylene foam layer 105 and the resin layer containing the inorganic filler and the polypropylene resin. Although it does not specifically limit as such a low melting point polyolefin resin, For example, a polypropylene resin can be used and the random copolymer of propylene and an alpha olefin is preferable.
Here, the resin layer containing the inorganic filler and the polypropylene resin may be a non-foamable resin layer such as the first non-foamable resin layer 110 and the second non-foamable resin layer 120 described above, or a foamable resin layer May be. From the viewpoint of further improving the mechanical properties such as flexural properties and tensile properties, heat resistance, moisture resistance, dimensional stability and the like of the polypropylene based foam sheet 100, the resin layer containing the inorganic filler and the polypropylene based resin is the first described above. Non-foamable resin layers such as the non-foamable resin layer 110 and the second non-foamable resin layer 120 are preferable.

The polypropylene-based foam layer 105 can be obtained, for example, by foam-molding the above-described polypropylene-based resin composition into a sheet using an extruder.
As a foaming agent at the time of shaping | molding of the polypropylene-type foam layer 105, a chemical foaming agent, a carbon dioxide gas, etc. are mentioned.
As a chemical foaming agent, sodium bicarbonate, ammonium bicarbonate, various carboxylates, sodium borohydride, azodicarbamide, N, N-dinitrosopentamethylenetetramine, P, P-oxybis (benzenesulfonylhydrazide) , Azobisisobutyronitrile, para-toluenesulfonyl hydrazide and the like.
As carbon dioxide gas, any of gaseous state, liquid state or supercritical state can be supplied.

The chemical blowing agent is preferably blended with the polypropylene resin composition and uniformly mixed before being introduced into the extruder.
Moreover, when using a carbon dioxide gas as a foaming agent, after a polypropylene resin composition will be in the state knead | mixed and plasticized in the extruder, it is preferable to press-in directly in an extruder.

  The expansion ratio of the polypropylene resin composition is not particularly limited, and can be appropriately determined in consideration of various physical properties of the obtained polypropylene foam sheet 100.

<Applications of polypropylene-based foam sheet>
The polypropylene-based foam sheet 100 according to the present embodiment is excellent in the lightness and performance balance of mechanical properties, and thus is an alternative to wood boards, in particular as a substitute for high rigidity wood boards such as hardboards and medium density fiber boards. It can be used.
More specifically, building materials such as floor materials, wall materials, door materials, interior materials, exterior materials, window frames, etc .; furniture; electric and electronic parts; partition materials; heat insulating materials; packaging materials; Seat; toy; curing board; miscellaneous goods; can be used as sports goods etc. More specifically, packing, distribution containers, sleepers, backing plates, floor plates, curing plates, spacers, signboards, shelves, back plates, bottom plates, insoles, ceiling materials, core materials, shock absorbing materials, sound absorbing materials, It can be used as a reinforcing plate, base plate, tatami floor, container, component jig, material for transportation, deck board, member for events and disasters, concrete form, bed, musical instrument and the like.

<Articles>
The article according to the present embodiment includes at least the polypropylene foam sheet 100 according to the present embodiment as a component.
As articles according to the present embodiment, for example, building materials such as floor materials, wall materials, door materials, interior materials, exterior materials, window frames, etc .; furniture; electric and electronic parts; partition materials; heat insulating materials; packaging materials; Parts for interior and exterior; cosmetic sheet; toy; curing plate; sundries; More specifically, packing, distribution containers, sleepers, backing plates, floor plates, curing plates, spacers, signboards, shelves, back plates, bottom plates, insoles, ceiling materials, core materials, shock absorbing materials, sound absorbing materials, Reinforcing boards, baseboards, tatami floors, containers, component jigs, materials for transportation, deck boards, members for events and disasters, concrete forms, beds, musical instruments, etc. may be mentioned. These articles | goods can be manufactured based on well-known information, using the polypropylene-type foam sheet 100 which concerns on this embodiment as a structural member.

  Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than the above can also be adopted.

  EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

1. Measurement Method (1) Density of Polypropylene-Based Foam Sheet A test piece was cut out of a polypropylene-based foam sheet, and the mass (g) of the test piece was divided by the volume (cm ³ ) obtained from the outer dimensions of the test piece.

(2) MFR of polypropylene resin
It was measured at 230 ° C. under a load of 2.16 kg in accordance with ASTM D1238.

(3) Mz / Mw of polypropylene resin
A 20 mg sample was dissolved in 20 ml of a mobile phase for GPC measurement at 145 ° C., and the obtained solution was filtered through a sintered filter with a pore size of 1.0 μm to obtain a measurement sample.
Next, using a gel permeation chromatograph (trade name “HLC-8321 GPC / HT type”) manufactured by Tosoh Corp., the Z average molecular weight (Mz) and weight average molecular weight (Mw) of the polypropylene resin are determined as follows. It measured and calculated Mz / Mw.
For the separation column, two trade names "TSKgel GMH6-HT" and two trade names "TSKgel GMH6-HTL" were used. The column size is 7.5 mm in inner diameter and 300 mm in length, the column temperature is 140 ° C., o-dichlorobenzene (Wako Pure Chemical Industries, Ltd.) is used as the mobile phase, and BHT (Wako Pure Chemical Industries, Ltd.) as an antioxidant. Company) 0.025% by weight was used.
The mobile phase was moved at a rate of 1.0 ml / min, the sample injection amount was 400 μl, and a differential refractometer was used as a detector. The standard polystyrene used was manufactured by Tosoh Corporation. The molecular weight is a value universally calibrated and converted to a polypropylene resin.

(4) Flexural modulus of a polypropylene-based foam sheet The flexural modulus of a polypropylene-based foam sheet is the thickness of a test specimen under an environment of 23 ° C. and 50% RH with reference to the flexural strength test described in JIS A5905. Measured at 1 point each in the MD and TD directions under the conditions of 3 mm, test piece width: 50 mm, test piece length: 150 mm, span distance: 100 mm, bending speed: 50 mm / min, and their average value is adopted did.

(5) Evaluation of performance balance of lightness and mechanical properties of polypropylene based foam sheet The specific flexural modulus (flexural modulus / density) of polypropylene based foam sheet is calculated, and the lightness of polypropylene based foam sheet is based on the following criteria And the performance balance of mechanical properties was evaluated.
◎◎: specific flexural modulus of 6.0GPa · ^cm 3 / g excess ◎: specific flexural modulus of 5.0GPa · ^cm 3 / g excess 6.0GPa · ^cm 3 / g or less ○: specific flexural modulus 4 .0GPa · ^cm 3 / g excess 5.0GPa · ^cm 3 / g or less ×: specific flexural modulus of 4.0GPa · ^cm 3 / g or less

2. Raw materials The raw materials used in Examples and Comparative Examples are shown below.
(1) Polypropylene resin PP1: Propylene homopolymer (VP103W manufactured by Prime Polymer Co., MFR: 3 g / 10 min, Mz / Mw value: 14)
PP2: block copolymer of propylene and ethylene (MFR: 6.5 g / 10 min, Mz / Mw value: 14)
(2) Masterbatch PP Talc MB1 containing an inorganic filler and a polypropylene-based resin (manufactured by Sanfuku Kogyo Co., Ltd., Brand: MFP-TP20, composition: containing 20% by mass of propylene homopolymer and 80% by mass of talc)
Here, PP talc MB1 was used after being heat-treated at 105 ° C. for 18 hours to reduce the water content of talc to 0.05% by mass.

3. Preparation of a polypropylene-based foam layer As a molding machine, a single-screw extruder (cylinder inner diameter D: 50 mm, full flight screw, screw effective length L when L / D: 32 mm, carbon dioxide gas supply position: from screw supply part side) 17.5D), T-die (die width: 320 mm, lip opening: 0.5 mm), cooling roll (outside diameter 50 mm, steel with mirror finish hard chrome plating surface treatment, water-cooled type), carbon dioxide gas supply device, An apparatus consisting of a cooling roll and a pulling machine was used.
First, each raw material is dry-blended according to the composition shown in Table 1 (units in the table are parts by mass), and the obtained mixture is charged into the hopper, and further from the carbon dioxide gas supply device to the middle of the cylinder of the extruder (position Carbon dioxide gas was injected at 17.5 D) at a pressure of 11 to 15 MPa. At this time, the injection amount of carbon dioxide gas was adjusted to be 0.1 to 0.3% by mass with respect to the extrusion amount. Each component material is melted and kneaded under the condition of temperature of 168 ~ 230 ° C of each part of cylinder and screw rotation number of 37 ~ 54rpm so that extrusion amount is 8 ~ 20kg / hour at resin temperature of 186 ~ 211 ° C of cylinder head. It extruded from T die. The extruded foam sheet is cooled by a cooling roll (roll internal water flow temperature 45 ° C.), taken off using a take-off machine (take-up speed 0.4 to 0.6 m / min), a polypropylene based sheet having a sheet width of about 300 mm Foamed layers 1 to 5 were obtained respectively.

4. Preparation of non-foamable resin layer Each material is introduced into the hopper with the composition shown in Table 2 (units in the table are parts by mass) in the extrusion molding machine used for preparation of the polypropylene based foam layer, cylinder temperature 205 to 230 ° C. Melt and knead each material under the conditions of 220 ° C die temperature and 22 to 28 rpm screw rotation, and extrude from T die so that the extrusion amount is 6 to 13 kg / hour at resin temperature 229 to 232 ° C of cylinder head. did. The extruded sheet was pulled using a pulling machine at a pulling speed of 1.0 m / min to obtain non-foamable resin layers 1 to 8 each having a sheet width of 290 to 300 mm.

[Examples 1 to 15, Comparative Example 1]
Polypropylene-based foam sheets were produced with the layer configurations shown in Tables 3 to 5 and evaluated. The obtained results are shown in Tables 3 to 5, respectively.
Here, the polypropylene-based foam sheet was laminated by inserting a thermal adhesive layer (polypropylene film consisting of a random copolymer having a melting point of 139 ° C., thickness: 0.06 mm) between each layer. Furthermore, in order to impart surface smoothness and releasability from the platen to the upper and lower flat portions of the sheet in contact with the platen of the heating press apparatus and the cooling press apparatus, heat resistance is applied to the top and bottom of the superposed sheets. A polyimide film having a mirror surface (arithmetic mean roughness Ra of 0.1 μm or less, thickness of 0.1 mm) was disposed.
It heat-pressed for 10 minutes at the temperature of 155 degreeC using the heat-press apparatus. Then, the sheet | seat containing an upper and lower polyimide film was inserted in the cooling press apparatus, and pressure cooling was carried out at the temperature of 25 degreeC, and the polypropylene foam sheet was obtained, respectively. In addition, before the heating press, a 3 mm-thick metal frame serving as a spacer was disposed in advance on the inner side of the upper and lower polyimide films and the outer periphery of each sheet. Thereby, the thickness of each polypropylene-based foam sheet was adjusted to 3 mm.

[Comparative Examples 2 and 3]
The polypropylene foam layers 4 and 5 were evaluated as polypropylene foam sheets, respectively. The obtained results are shown in Table 5, respectively.

Comparative Example 4
Each evaluation was carried out using Paronia (registered trademark) manufactured by Mitsui Chemicals Toshiro Co., Ltd. as a polypropylene-based foam sheet containing no inorganic filler. The obtained results are shown in Table 5.

[Reference Examples 1 and 2]
Each evaluation was performed using a commercially available hardboard (HDF) and a medium density fiber board (MDF) as a wood board. The obtained results are shown in Table 5, respectively.

As is clear from Tables 3 to 5, the polypropylene foam sheets of Examples 1 to 15 show the density and flexural modulus equal to or higher than those of wood boards such as hardboards and medium density fiberboards, and are lightweight And it was found that the performance balance of mechanical properties was excellent. That is, it can be understood that the polypropylene-based foam sheet 100 according to the present embodiment is suitable as a substitute for wood board.
On the other hand, the polypropylene foam sheets of Comparative Examples 1, 2 and 4 were all inferior in the balance of lightness and mechanical properties. In addition, the foaming ratio of the polypropylene-based foam sheet of Comparative Example 3 was not increased, the surface was roughened, it was difficult to form the foam sheet itself, and it was difficult to obtain the foam sheet.

  This application claims priority based on Japanese Patent Application No. 2017-005344 filed on Jan. 16, 2017, the entire disclosure of which is incorporated herein.

Claims (15)

A polypropylene foam sheet comprising a polypropylene resin and an inorganic filler, wherein
The density of the polypropylene-based foam sheet is 0.5 g / cm ³ or more and 1.0 g / cm ³ or less,
When the total thickness of the polypropylene-based foam sheet is T [mm], in the thickness direction of the polypropylene-based foam sheet,
The content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the surface area from the surface toward the center to 0.1 T [mm] is W ₁ ,
When the content of the inorganic filler relative to the total amount of the polypropylene resin and the inorganic filler in the central region from the center to the surface to ± 0.1 T [mm] is W ₂ ,
Polypropylene-based foam sheet satisfying the relationship of W ₁ > W ₂ In the polypropylene-based foam sheet according to claim 1,
The polypropylene-type foam sheet in which the said inorganic filler contains 1 type, or 2 or more types selected from a talc, mica, and a silica. In the polypropylene-based foam sheet according to claim 2,
The polypropylene-based foam sheet in which the said inorganic filler contains a talc. In the polypropylene-based foam sheet according to any one of claims 1 to 3,
The difference (W ₁ -W ₂ ) between the content (W ₁ ) of the inorganic filler in the surface region and the content (W ₂ ) of the inorganic filler in the central region is 5 parts by weight or more and 90 parts by weight or less Polypropylene-based foam sheet. The polypropylene-based foam sheet according to any one of claims 1 to 4,
The content (W ₁ ) of the inorganic filler in the surface area is 5 parts by mass or more and 90 parts by mass or less when the total amount of the polypropylene resin and the inorganic filler contained in the surface area is 100 parts by mass. There is a polypropylene-based foam sheet. In the polypropylene-based foam sheet according to any one of claims 1 to 5,
The content (W ₂ ) of the inorganic filler in the central region is 0 parts by mass or more and 50 parts by mass or less when the total amount of the polypropylene resin and the inorganic filler contained in the central region is 100 parts by mass. There is a polypropylene-based foam sheet. The polypropylene-based foam sheet according to any one of claims 1 to 6,
The polypropylene-based foam sheet in which the flexural modulus of elasticity of the polypropylene-based foam sheet measured at 23 ° C. and 50% RH is 1 GPa or more. In the polypropylene-based foam sheet according to any one of claims 1 to 7,
Polypropylene-based foam wherein the total content of the polypropylene-based resin and the inorganic filler in the polypropylene-based foam sheet is 50% by mass to 100% by mass, based on 100% by mass of the entire polypropylene-based foam sheet Sheet. The polypropylene-based foam sheet according to any one of claims 1 to 8,
The polypropylene-type foam sheet whose thickness of the said polypropylene-type foam sheet is 1 mm-30 mm. In the polypropylene-based foam sheet according to any one of claims 1 to 9,
A polypropylene-based foam layer containing the polypropylene-based resin and the inorganic filler;
A first non-foamable resin layer provided on one side of the polypropylene-based foam layer and containing the polypropylene-based resin and the inorganic filler;
A second non-foamable resin layer provided on the other surface of the polypropylene-based foam layer and containing the polypropylene-based resin and the inorganic filler;
A polypropylene based foam sheet comprising: In the polypropylene-based foam sheet according to claim 10,
The polypropylene-based foam sheet wherein the thickness of each of the first non-foamable resin layer and the second non-foamable resin layer is 0.1 mm or more and 5 mm or less. In the polypropylene-based foam sheet according to claim 10 or 11,
The ratio of the thickness of the first non-foamable resin layer to the thickness of the entire polypropylene-based foam sheet is 0.1 or more and 0.4 or less,
The polypropylene-based foam sheet wherein the ratio of the thickness of the second non-foamable resin layer to the thickness of the entire polypropylene-based foam sheet is 0.1 or more and 0.4 or less. The polypropylene-based foam sheet according to any one of claims 10 to 12,
The polypropylene-based foam sheet, wherein the first non-foamable resin layer and the second non-foamable resin layer have the same composition and the same thickness. In the polypropylene-based foam sheet according to any one of claims 1 to 13,
Polypropylene-based foam sheet used as a substitute for wood board.   An article comprising the polypropylene foam sheet according to any one of claims 1 to 14 as a component.

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