JP2022027537A - Stretched resin sheet, method for producing stretched resin sheet and resin pellet - Google Patents

Abstract

To provide a resin sheet obtained by molding a propylene-based resin composition blended with a flame retardant which can exhibit higher flame retardancy.SOLUTION: A stretched resin sheet contains a flame retardant, and a resin component containing a propylene-based resin as a main component, in which a degree of crystallization of a polypropylene component in the stretched resin sheet is 60-90%.SELECTED DRAWING: None

Description

The present invention relates to a stretched resin sheet, a method for producing a stretched resin sheet, and resin pellets.

Since plastic itself is a flammable material, it is desired to impart flameproofness or flame retardancy to a molded product made of plastic, for example, a resin sheet or the like. In particular, flame-retardant wallpapers used as building materials, flame-retardant posters used in stores, store stickers, seat members used in home appliances, tag labels used in automobiles, glass stickers used in railway vehicles, etc. have high flame-retardant levels. (For example, DIN4102, FMVSS-302, etc.) are required.

Propylene-based resins are known as useful raw materials for such molded products made of plastic. However, in order to achieve high flame retardancy in a resin composition containing a propylene-based resin, it is necessary to add a halogen-based flame retardant or a relatively large amount of an inorganic flame retardant.

Further, as a resin composition imparted with flame retardancy without blending a halogen-based flame retardant or an inorganic flame retardant, a specific NOR-type HALS compound (NOR-type hindered amine-based light stabilizer) and a specific phosphorus-based compound can be used. Is known as a propylene-based resin composition containing the above (see, for example, Patent Documents 1 and 2).

Special Table 2015-510023 Gazette Japanese Unexamined Patent Publication No. 2017-066299

In recent years, from the viewpoint of ensuring safety and demanding expansion of applications, higher flame retardancy has been required for molded products of resin sheets obtained by molding propylene-based resin compositions.
However, the resin sheet formed by using the propylene-based resin composition described in Patent Documents 1 and 2 is not sufficient to meet the required level of high flame retardancy, and there is room for improvement. ..

Therefore, an object of the present invention is to provide a resin sheet capable of exhibiting higher flame retardancy in a resin sheet obtained by molding a propylene-based resin composition containing a flame retardant.

As a result of diligent studies to solve the above problems, the present inventors have obtained it when producing a flame-retardant stretched resin sheet from a resin component containing a flame retardant as a main component and containing a propylene-based resin as a main component. By adjusting the crystallinity of the polypropylene component in the resin sheet to a higher value than before, it is possible to obtain a better flame retardant effect with the use of a relatively small amount of flame retardant, and it is as difficult as before. We have found that a higher flame retardant effect can be obtained depending on the amount of the flame retardant used, and have completed the present invention.

［８］難燃剤と、プロピレン系樹脂を主成分とする樹脂成分とを含むプロピレン系樹脂組成物を用いて、溶融押出することによりシート状に成形し、次いで、延伸して延伸樹脂シートを製造する延伸樹脂シートの製造方法であって、
前記プロピレン系樹脂の結晶化度が５１～５５％であることを特徴とする、延伸樹脂シートの製造方法。
［９］前記延伸する工程において、樹脂シートの延伸が２軸延伸である、［８］に記載の延伸樹脂シートの製造方法。
［１０］前記２軸延伸において、縦方向の延伸倍率が２倍より大きく１０倍以下であり、かつ横方向の延伸倍率が２倍より大きく２０倍以下である、［９］に記載の延伸樹脂シートの製造方法。
［１１］難燃剤と、プロピレン系樹脂を主成分とする樹脂成分とを含有する樹脂ペレットであって、
前記プロピレン系樹脂の結晶化度が５１～５５％であることを特徴とする、樹脂ペレット。 That is, the present invention provides various specific embodiments shown below.
[1] A stretched resin sheet containing a flame retardant and a resin component containing a propylene-based resin as a main component.
A stretched resin sheet, characterized in that the degree of crystallinity of the polypropylene component in the stretched resin sheet is 60 to 90%.
[2] The stretched resin sheet according to [1], wherein the flame retardant contains a NOR type HALS compound.
[3] The stretched resin sheet according to [2], wherein the flame retardant contains a NOR-type HALS compound and a phosphorus-based compound.
[4] The stretched resin sheet according to [2] or [3], wherein the content of the NOR-type HALS compound is 0.1 to 3 parts by mass with respect to 100 parts by mass of the resin component.
[5] The stretched resin sheet according to any one of [3] to [4], wherein the content of the phosphorus-based compound is 0.1 to 7 parts by mass with respect to 100 parts by mass of the resin component.
[6] The stretched resin sheet according to any one of [3] to [5], wherein the ratio of the content of the phosphorus-based compound to the content of the NOR-type HALS compound is 1 to 30 on a mass basis.
[7] The stretched resin sheet according to any one of [2] to [6], wherein the NOR-type HALS compound is a NOR-type HALS compound represented by the following formula (1).

[8] Using a propylene-based resin composition containing a flame retardant and a resin component containing a propylene-based resin as a main component, a propylene-based resin composition is melt-extruded to form a sheet, and then stretched to produce a stretched resin sheet. This is a method for manufacturing a stretched resin sheet.
A method for producing a stretched resin sheet, wherein the propylene-based resin has a crystallinity of 51 to 55%.
[9] The method for producing a stretched resin sheet according to [8], wherein the stretching of the resin sheet is biaxial stretching in the stretching step.
[10] The stretched resin according to [9], wherein in the biaxial stretching, the stretching ratio in the longitudinal direction is greater than 2 times and 10 times or less, and the stretching ratio in the lateral direction is greater than 2 times and 20 times or less. Sheet manufacturing method.
[11] A resin pellet containing a flame retardant and a resin component containing a propylene-based resin as a main component.
A resin pellet characterized in that the crystallinity of the propylene-based resin is 51 to 55%.

According to the present invention, it is possible to provide a resin sheet capable of exhibiting higher flame retardancy in a resin sheet obtained by molding a propylene-based resin composition containing a flame retardant.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below is an example for explaining the present invention, and the present invention is not limited to these contents.

[Stretched resin sheet]
The stretched resin sheet of the present invention contains a resin component containing a propylene-based resin as a main component and a flame retardant.
The crystallinity of the polypropylene component in the stretched resin sheet of the present invention is 60 to 90%.
The stretched resin sheet of the present invention showing a high crystallinity of the polypropylene component in the stretched resin sheet as high as 60 to 90% is a stretched resin sheet showing higher flame retardancy.
A preferred embodiment of the stretched resin sheet of the present invention is a stretched resin sheet obtained by molding and stretching a propylene-based resin composition containing a resin component containing a propylene-based resin as a main component and a flame retardant. Be done.
In the present specification, a molded product obtained by molding a propylene-based resin composition into a sheet shape is referred to as a "resin sheet", that is, a molded product molded into a sheet shape is referred to as a "resin sheet" regardless of the presence or absence of a stretching step. .. For example, even when a resin sheet obtained by melt-extruding a propylene-based resin composition into a sheet is further subjected to a stretching step, the sheet after the stretching step may be referred to as a “resin sheet”.
However, in the present specification, when it is clarified that the resin sheet is a resin sheet after the stretching step, the stretched resin sheet obtained through the stretching step is referred to as a "stretched resin sheet".
The propylene-based resin composition contains a resin component and a flame retardant, and appropriately contains other components as necessary.
The components constituting the propylene-based resin composition will be described below.

(Resin component)
As the resin component, as long as it contains a propylene-based resin as a main component, it may contain other resins.
Here, the fact that the propylene-based resin is contained as the main component means that the resin having the highest content among the resins constituting the resin component is the propylene-based resin.

<Propene resin>
Propylene-based resin is used as the main component of the resin composition, and imparts film-forming property, water resistance, durability, light weight, physical strength, and light transmission to the resin sheet formed by using the resin composition. ..
The crystallinity of the propylene-based resin used for ordinary sheet molding is less than 51% (generally 40 to 50.9%), but in the present invention, the polypropylene component in the stretched resin sheet after sheet molding In order to make the crystallinity 60 to 90%, the polypropylene resin is mixed and used so that the crystallinity of the entire propylene resin is 51% or more.

The propylene-based resin is not particularly limited as long as propylene is used as the main monomer. For example, an isotactic polymer obtained by homopolymerizing propylene, a syndiotactic polymer, or the like can be mentioned. Further, it is a copolymer of propylene as a main component and α-olefins such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. , Propylene-α-olefin copolymer and the like can also be used. The copolymer may be a binary system in which the monomer component is a binary system or a multidimensional system having a ternary system or more, and may be a random copolymer or a block copolymer. Further, the propylene homopolymer and the propylene copolymer may be used in combination. Among these, the propylene homopolymer is preferable because it is easy to handle as the main raw material of the resin sheet.

As the propylene-based resin, various conventionally known propylene-based resins can be used. Although not limited in any way, the MFR (Melt Flow Rate) of the propylene resin is usually 0.5 g / 10 minutes or more, preferably 1.0 g / 10 minutes or more, and usually 30 g / 10 minutes. Minutes or less, preferably 20 g / 10 minutes or less.

<< High Crystal Polypropylene >>
The propylene-based resin according to the present invention contains highly crystalline polypropylene. Here, the high crystalline polypropylene means polypropylene having a crystallinity of 51% or more, preferably 53% or more, and particularly preferably 55% or more.
When high-crystal polypropylene is contained in the propylene-based resin, the crystallinity of the polypropylene component in the stretched resin sheet can be increased in the stretched resin sheet obtained by molding and stretching the propylene-based resin composition.
As the propylene-based resin according to the present invention, only high-crystal polypropylene may be used, but as a preferred embodiment, general polypropylene having a crystallinity of less than 51% (hereinafter, also referred to as general-purpose polypropylene), for example, Among the propylene-based resins formed of general-purpose polypropylene having a crystallinity of 40% or more and less than 51%, a propylene-based resin containing high-crystal polypropylene in which a part of the general-purpose polypropylene is changed to high-crystal polypropylene can be mentioned. ..
The high crystalline polypropylene contained in the propylene-based resin may be used in one type or in two or more types.

The content of high crystalline polypropylene in the propylene-based resin is 10 parts by mass or more, preferably 20 parts by mass or more, and more preferably 25 parts by mass or more with respect to 100 parts by mass of the propylene-based resin. The content is 50 parts by mass or less, preferably 45 parts by mass or less, and more preferably 40 parts by mass or less with respect to 100 parts by mass of the propylene-based resin. When the content of high crystalline polypropylene is at least the above lower limit, the crystallinity of the polypropylene component in the stretched resin sheet can be increased to a desired value, and the flame retardancy of the stretched resin sheet is improved. Further, when the content of the high crystalline polypropylene is not more than the above upper limit, the content of the high crystalline polypropylene increases, which hinders the content of the flame retardant, reduces the content of the flame retardant, or uniformly disperses the flame retardant. It is possible to effectively suppress the harmful effect of reducing the flame retardancy that the flame retardant is hindered and a flammable portion is generated. Further, when it is not more than the above upper limit, the amount of high-cost high-crystal polypropylene used can be suppressed, which is excellent in economy.
When two or more types of high-crystal polypropylene are used, the preferable content of the high-crystal polypropylene is a value obtained by adding the contents of each high-crystal polypropylene.

<<< Propylene resin crystallinity (51-55%) and its measurement method >>>
The crystallinity of the propylene-based resin is 51% or more, preferably 51.5% or more, and more preferably 52% or more. The crystallinity is 55% or less, preferably 54% or less, and more preferably 53% or less. When the propylene-based resin is blended from two or more types of polypropylene, the crystallinity of the propylene-based resin can be obtained by arithmetic mean calculation.
When measuring the crystallinity of various polypropylenes as raw materials for propylene-based resins, a method using a DSC (Differential Scanning Calorimeter) can be used.
Hereinafter, a method for measuring the crystallinity of polypropylene using the DSC method will be described in detail.
The target polypropylene is set in a differential scanning calorimetry device, and the relationship (DSC curve) between the temperature [° C.] and the heat of melting [J / g] is measured. The obtained DSC curve can be compared with the DSC curve of polypropylene having a crystallinity of 100%, and the crystallinity of the propylene resin can be calculated from the difference in the amount of heat of fusion [J / g].

In the present invention, a propylene-based resin composition containing the above-mentioned polypropylene having a crystallinity of less than 51% and highly crystalline polypropylene is usually used as a starting material, which is pelletized and melt-extruded according to a conventional method to form a sheet. A stretched resin sheet is obtained through the stretching step. The content of highly crystalline polypropylene in the propylene-based resin composition as a starting material at this time is usually 5 parts by mass or more, preferably 10 parts by mass or more with respect to 100 parts by mass of the propylene-based resin composition. , More preferably 15 parts by mass or more, still more preferably 22 parts by mass or more. The content is 42 parts by mass or less, preferably 36 parts by mass or less, and more preferably 32 parts by mass or less with respect to 100 parts by mass of the propylene resin composition. The crystallinity of the propylene component in the finally obtained stretched resin sheet changes depending on this blending amount.

<Other resins>
As the resin component contained in the propylene-based resin composition, other thermoplastic resins may be contained in addition to the above-mentioned propylene-based resin.
Examples of other thermoplastic resins include ethylene resins, crystalline olefin resins such as polymethyl-1-pentene, nylon-6, nylon-6,6, nylon-6,10, nylon-6,12 and the like. Examples thereof include amide resins, polyethylene terephthalates or copolymers thereof, thermoplastic polyesters such as polyethylene naphthalate and aliphatic polyesters, and thermoplastic resins such as polycarbonates, atactic polystyrenes, syndiotactic polystyrenes and polyphenylene sulfides. These can also be used by mixing two or more kinds. Of these, those containing a small amount of ethylene resin are preferable.
The content is usually 1 to 20 parts by mass, preferably 3 to 15 parts by mass with respect to 100 parts by mass of the propylene-based resin.

<< Ethylene resin >>
Similar to the above-mentioned propylene-based resin, the ethylene-based resin imparts film-forming property, water resistance, durability, light weight, physical strength, and light transmission to the resin sheet formed by using the resin composition.

Examples of the ethylene resin include high-density polyethylene having a density of 0.940 to 0.965 g / cm ³ , medium-density polyethylene having a density of 0.920 to 0.935 g / cm ³ , and a density of 0.900 to 0. Examples thereof include ethylene-based resins such as low-density polyethylene of 920 g / cm ³ . The crystallinity of these ethylene resins is usually 40 to 70%. Further, it is a copolymer of ethylene as a main component and α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. , Ethylene-α-olefin copolymer can also be used. Further, as the ethylene resin, an ethylene-vinyl acetate copolymer, an ethylene-cyclic olefin copolymer or the like can also be used. Among these, high-density polyethylene is preferable.

(Flame retardants)
The flame retardant is not particularly limited as long as it imparts a flame retardant effect to the resin sheet, and can be appropriately selected depending on the intended purpose. However, in the present invention, the NOR type HALS compound and the phosphorus compound are used. It is preferable to use, and it is particularly preferable to use both of them in combination.

<NOR type HALS compound>
By containing the NOR-type HALS compound, the propylene-based resin composition according to the present invention functions as an excellent radical scavenger during combustion of the resin composition and the resin sheet containing the NOR-type HALS compound, and exhibits a function of stopping the combustion reaction. .. That is, excellent flame retardancy can be imparted to the resin composition and the resin sheet. In addition, resin compositions and resin sheets that suppress deterioration of propylene-based resins due to ultraviolet rays, etc., impart excellent weather resistance, suppress deterioration of propylene-based resins in high-temperature environments, and have excellent heat resistance. It also has the effect of being able to be obtained.
The NOR type HALS compound is not particularly limited as long as it is a compound having an N-alkoxyl group (> N-OR) structure. For example, NOR type HALS compounds described in JP-A-2002-507238, International Publication No. 2005/082852, International Publication No. 2008/003605 and the like can be mentioned. Among them, the NOR type HALS compound represented by the following formula (1) or the following formula (2) is preferable.

（式（２）中、Ｒは下記式（２－１）で表される基である。）

(In the formula (2), R is a group represented by the following formula (2-1).)

The NOR-type HALS compound represented by the formula (1) or the formula (2) functions as an excellent radical scavenger during combustion of the resin composition and the resin sheet containing the compound, and exhibits a function of stopping the combustion reaction. That is, excellent flame retardancy can be imparted to the resin composition and the resin sheet.
In particular, the NOR-type HALS compound represented by the formula (1) is particularly preferable because the compound itself is more stable than other NOR-type HALS compounds and the coloring of the resin composition and the resin sheet can be well prevented.

Further, since the NOR type HALS compound represented by the formula (1) is liquid at room temperature, it is uniformly finely dispersed in the resin composition during melt-kneading with the propylene-based resin, and has excellent heat resistance and difficulty. Easy to exhibit flammability.

The content of the NOR-type HALS compound in the propylene-based resin composition according to the present invention is usually 0.1 part by mass or more, preferably 0.2 part by mass or more, more preferably 0.2 parts by mass or more with respect to 100 parts by mass of the resin component. Is 0.5 parts by mass or more. The content is usually 3 parts by mass or less, preferably 2 parts by mass or less, and more preferably 1.5 parts by mass or less with respect to 100 parts by mass of the resin component. If the amount of the NOR-type HALS compound used is less than the above lower limit, a sufficient flame retardant effect cannot be obtained, while if it is more than the above upper limit, there is no big difference in the effect, and stickiness and cost increase due to bleeding occur. It tends to occur. The NOR-type HALS compound may be used alone or in combination of two.

<Phosphorus compound>
As a flame retardant, phosphorus-based compounds have the function of stopping the combustion reaction by carbonizing (charging) and solidifying the combustion components of the propylene-based resin during combustion to form a film that blocks air, and NOR. It shows the function as a radical trapping agent similar to the type HALS compound, and the function of diluting the oxygen concentration with phosphine gas generated during the decomposition of the phosphorus-based flame retardant. When a predetermined amount of the phosphorus-based compound is used in combination with the NOR-type HALS compound, excellent flame retardancy can be imparted to the propylene-based resin composition and the resin sheet, which is more preferable.

The phosphorus-based compound is not particularly limited as long as it is a phosphorus-based compound exhibiting a flame-retardant effect, and can be appropriately used depending on the intended purpose. For example, a phosphoric acid compound, a phosphoric acid compound, or a phosphoric acid ester compound can be used. , Phosphoric acid ester compound and the like can be used.
Further, as the phosphorus-based compound used in the present invention, any phosphorus-based compound having no flammable point or a phosphorus-based compound having a flammable point can be used, but a phosphorus-based compound having a flammable point is preferable. , More preferably, a phosphorus-based compound having a ignition point of 270 ° C. or higher can be mentioned. Among the phosphorus compounds having a flash point of 270 ° C. or higher, a phosphorus compound having a flash point of 320 ° C. or higher, more preferably 360 ° C. or higher, still more preferably 400 ° C. or higher, and particularly preferably 440 ° C. or higher can be mentioned. Be done. When the flash point of the phosphorus-based compound is 270 ° C. or higher, higher flame retardancy can be imparted to the propylene-based resin composition or the resin sheet.

The degree of hydrolysis of the phosphorus compound is 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1.5% by mass or less. When the phosphorus-based compound is hydrolyzed, the molecules become finer, so that the hydrolyzed phosphorus-based compound becomes easier to move in the resin, and the hydrolyzed phosphorus-based compound bleeds out during stretching, heating, and light irradiation. It will be easier to do. When the degree of hydrolysis of the phosphorus compound is not more than the above upper limit, it is possible to suppress a decrease in flame retardant effect and a decrease in moldability and printability due to bleed-out.

When the phosphorus-based compound is used from any of a phosphite compound, a phosphoric acid compound, a phosphite ester compound, and a phosphoric acid ester compound, the phosphite ester compound and the phosphoric acid ester compound are preferable among them, and phosphorus is preferable. A phosphite ester compound is further preferable from the viewpoint of being excellent in the effect of suppressing bleed-out of the system compound.

As the phosphite ester compound, a phosphite ester compound represented by the general formula P (OR ³ ) ₃ or the formula (3) described later is preferable.

In general formula P (OR ³ ) ₃ , R ³ comprises substituted or unsubstituted C _1-30 alkyl groups, substituted or unsubstituted C _3-30 cycloalkyl groups, substituted or unsubstituted C _6-30 aryl groups. show. The plurality of ^R3s may be the same as or different from each other. Among these, at ^least one of R3 is preferably a substituted or unsubstituted C _{6 to 30} aryl group, more preferably a substituted or unsubstituted C _{6 to 15} aryl group, and has a substituent. It is particularly preferable that the C _{6 to 15} aryl group is used. Examples of the substituent having an aryl group include C _{1 to 10} alkyl groups such as a methyl group, an ethyl group and a tert-butyl group, C _{1 to 10} alkoxy groups such as a methoxy group and an ethoxy group, and C ₁ is preferable. It is a _{~ 5} alkyl group. The number of substituents is not particularly limited, but is usually 1 or more, preferably 2 or more, and usually 5 or less, preferably 3 or less.

これらの中でも、Ｒ^４及びＲ^５は、各々独立に置換又は無置換のＣ_６～３０アリール基であることが好ましく、置換又は無置換のＣ_６～１５アリール基であることがより好ましく、置換基を有するＣ_６～１５アリール基であることが特に好ましい。 In the phosphite ester compound represented by the following formula ( ³ ), ^R4 and R5 may be the same or different, and are substituted or unsubstituted C1 _{to 30} alkyl groups, substituted or unsubstituted. C _3-30 cycloalkyl groups, substituted or unsubstituted C _6-30 aryl groups are shown.

Among these, R ⁴ and R ⁵ are preferably independently substituted or unsubstituted C _{6 to 30} aryl groups, more preferably substituted or unsubstituted C _{6 to 15} aryl groups, respectively. A C _6-15 aryl group having a group is particularly preferable.

式（４）中、Ｒ^６、Ｒ^７、Ｒ^９、Ｒ^１０、Ｒ^１２、Ｒ^１３、Ｒ^１５及びＲ^１６は、それぞれ独立に水素原子又はＣ_１～５アルキル基を示し、Ｒ^８、Ｒ^１１、Ｒ^１４及びＲ^１７は、それぞれ独立にＣ_１～５アルキル基、Ｃ_６～１５アリール基又はアラルキル基を示す。アラルキル基は、Ｃ_１～５アルキル基の水素原子の１つがＣ_６～１５アリール基で置換された置換基である。また、ｂ１～ｂ４は、それぞれ独立に０～３の整数を示す。Ｒ^６、Ｒ^７、Ｒ^９、Ｒ^１０、Ｒ^１２、Ｒ^１３、Ｒ^１５及びＲ^１６はメチル基が好ましく、ｂ１～ｂ４は０が好ましい。 When R ⁴ and R ⁵ are C _{6 to 15} aryl groups having a substituent, the phosphite ester compound represented by the formula (3) is preferably a compound represented by the following formula (4).

In formula (4), R ⁶ , R ⁷ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a C _1-5 alkyl group, and are R ⁸ and R, respectively. ¹¹ , R ¹⁴ and R ¹⁷ independently represent a C _1-5 alkyl group, a C _6-15 aryl group or an aralkyl group, respectively. The aralkyl group is a substituent in which one of the hydrogen atoms of the C _{1 to 5} alkyl group is substituted with a C _{6 to 15} aryl group. Further, b1 to b4 each independently indicate an integer of 0 to 3. R ⁶ , R ⁷ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁵ and R ¹⁶ are preferably methyl groups, and b1 to b4 are preferably 0.

Specific examples of the phosphite ester compound represented by the formula (3) or (4) include bis (2,4-dicumylphenyl) pentaerythritol diphosphite; 2,2'-methylenebis (4,6-methylenebis). Di-tert-butylphenyl) 2-ethylhexylphosphite and the like can be mentioned.

Specific examples of the phosphoric acid ester compound include compounds having an ester structure of pentaerythritol and two phosphoric acids in the main skeleton; diethylaluminum phosphinate; phenol, 4,4'-(propane-2,2-diyl) diyl. Reaction products of phenol and trichlorophosphine oxide; aromatic phosphonates; resorcinol-bis-diphenyl phosphate; methyl-ethyl-aluminum phosphinate and the like.

The degree of hydrolysis [mass%] of the phosphorus-based compound described above is the degree of hydrolysis of the phosphorus-based compound when 5 g of the phosphorus-based compound is allowed to stand for 500 hours under humidifying and heating conditions at a relative humidity of 95% and 50 ° C. The rate of increase in mass. This value is an index of the ease of hydrolysis of the phosphorus compound, and the larger the value, the easier it is to hydrolyze.
When the phosphorus-based compound is hydrolyzed, the flame-retardant effect may be lowered, and the moldability and printability may be lowered due to bleed-out. Therefore, it is preferable that the value of the degree of hydrolysis of the phosphorus-based compound is small.

The above phosphorus compounds may be used alone or in combination of two or more.

The content of the phosphorus compound in the propylene-based resin composition of the present invention is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.3 parts by mass or more with respect to 100 parts by mass of the resin component. Is 0.6 parts by mass or more. The content is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 4 parts by mass or less with respect to 100 parts by mass of the resin component.
When the content of the phosphorus-based compound is at least the above lower limit, the heat resistance of the propylene-based resin composition and the flame retardancy of the resin sheet can be improved by the combined use with the NOR-type HALS compound. Further, when the content of the phosphorus-based compound is not more than the above upper limit, the bleed-out of the phosphorus-based compound in the resin sheet can be further reduced, so that the stickiness of the resin sheet can be suppressed and the moldability is excellent.
That is, by setting the content of the phosphorus-based compound within a predetermined range, the heat resistance of the propylene-based resin composition, the flame retardancy of the resin sheet, and the bleed-out suppressing effect of the phosphorus-based compound can be balanced.

<Content ratio of NOR type HALS compound and phosphorus compound>
In the propylene-based resin composition according to the present invention, the ratio of the content of the phosphorus-based compound to the content of the NOR-type HALS compound [(content of the phosphorus-based compound) / (content of the NOR-type HALS compound)] is the mass. By standard, it is preferably 1 or more, more preferably 1.03 or more, preferably 30 or less, more preferably 14 or less, still more preferably 6 or less, and particularly preferably 4 or less. That is, it tends to be preferable that the content of the phosphorus-based compound is relatively equal to or higher than the content of the NOR-type HALS compound. When the ratio of the content of the phosphorus-based compound to the content of the NOR-type HALS compound is within the above range, the flame retardancy is particularly improved. When the ratio of the content of the phosphorus-based compound to the content of the NOR-type HALS compound is at least the above lower limit, higher flame retardancy can be imparted to the propylene-based resin composition or the resin sheet. Further, when it is not more than the above upper limit, it is economical because the effect according to the blending amount can be obtained, and it is preferable because the bleed-out of the phosphorus compound can be suppressed.

(Other ingredients)
The propylene-based resin composition according to the present invention may contain the above-mentioned resin component and other components other than the above-mentioned flame retardant as long as the effect of the present invention is not impaired.
For example, known additives such as inorganic fillers, organic fillers, dispersants, heat stabilizers, antioxidants, ultraviolet stabilizers, blocking inhibitors, crystal nucleating agents, and lubricants may be blended.

<Inorganic filler>
The propylene-based resin composition according to the present invention usually preferably contains an inorganic filler. For example, it is desirable to add titanium oxide in order to improve the whiteness or opacity of the resin sheet, or to add calcium carbonate as a porous nucleating material when the resin sheet is stretched.
The stretched resin sheet of the present invention containing an inorganic filler can be used as so-called synthetic paper.

The content of the inorganic filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, still more preferably, with respect to 100 parts by mass of the resin component. Is 20 parts by mass or less. When the content of the inorganic filler is at least the above lower limit, the whiteness or opacity of the resin sheet is easily improved and the resin sheet is easily made porous. Further, when the content of the inorganic filler is not more than the above upper limit, it is easy to suppress the decrease in flame retardancy.

Specific examples of the inorganic filler include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, zeolite, titanium oxide, barium sulfate, zinc oxide, magnesium oxide, diatomaceous earth, fine powder such as silicon oxide, and hollow glass beads. Can be mentioned. Among these, titanium oxide or calcium carbonate (heavy calcium carbonate or light calcium carbonate) is particularly preferable.

The average particle size of the inorganic filler can be appropriately selected depending on the intended purpose, and is usually 0.1 μm or more and 10 μm or less.

<Dispersant>
The dispersant is used, for example, for the purpose of highly dispersing the above-mentioned inorganic filler in the resin composition. Examples of the dispersant include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, maleic anhydride-modified polypropylene, and salts thereof.

The content of the dispersant is not particularly limited, but it is preferably blended in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the resin component, depending on the content of the inorganic filler. When the content of the dispersant is 0.01 parts by mass or more, the inorganic filler tends to be uniformly and finely dispersed in the propylene resin, and the decrease in flame retardancy tends to be suppressed. Further, when the content of the dispersant is 5 parts by mass or less, it is easy to prevent stickiness and inhibition of light transmission due to the excess dispersant.

(Characteristics of stretched resin sheet)
<Sheet configuration>
The stretched resin sheet of the present invention contains a layer obtained by molding and stretching the propylene-based resin composition. The method for manufacturing the stretched resin sheet will be described in detail below.
The stretched resin sheet may have a single-layer structure or a multi-layer structure as long as it includes the above layers.
When the stretched resin sheet has a multi-layer structure, the propylene-based resin compositions constituting each layer may be the same or different. For example, if the content of the phosphorus compound in the outermost layer is relatively large, the flame retardancy of the stretched resin sheet tends to be improved.

The number of stretching axes in the stretched resin sheet of the present invention may be one direction or two or more directions.

The thickness of the stretched resin sheet of the present invention may be appropriately set according to the desired performance and is not particularly limited, but is preferably 30 μm or more, more preferably 40 μm or more, and further preferably 50 μm or more. preferable. The thickness of the stretched resin sheet is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. When the thickness of the stretched resin sheet is at least the above lower limit, the resin sheet has sufficient mechanical strength, and it is easy to prevent breakage during stretch molding or use of the resin sheet. Further, when the thickness of the stretched resin sheet is not more than the above upper limit, the resin sheet does not become too heavy and tends to be easy to handle.
The thickness of the stretched resin sheet is a value measured in accordance with JIS K7130: 1999. For example, the thickness of the stretched resin sheet can be determined according to JIS K7130: 1999 using a constant pressure thickness measuring instrument (device name: PG-01J, manufactured by Teclock Co., Ltd.).
When the stretched resin sheet has a multi-layer structure, it is a value measured as a whole of the plurality of layers. For the thickness of each layer when the stretched resin sheet has a multi-layer structure, observe the cross section using an electron microscope, determine the interface between the layers from the appearance, determine the thickness ratio, and determine the thickness ratio of the entire stretched resin sheet measured above and each layer. Calculated from the product of the thickness ratios of.

<Crystallinity>
The crystallinity of the polypropylene component in the stretched resin sheet of the present invention is 60 to 90%.
When a stretched resin sheet is formed using a propylene-based resin made of general-purpose polypropylene having a crystallinity of 40% or more and less than 51%, which is generally used as polypropylene, the crystallinity of the polypropylene component in the stretched resin sheet is high. , Approximately 53-58%. The value of the crystallinity varies slightly depending on the molding conditions and stretching conditions of the resin sheet, but it is about 58% at the highest.
However, a part of the general-purpose polypropylene is changed to a high crystallinity polypropylene having a crystallinity of 51% or more to form a propylene-based resin containing the high crystallinity polypropylene, and the propylene-based resin containing the high crystallinity polypropylene is used. When a stretched resin sheet is formed, the crystallinity of the polypropylene component in the stretched resin sheet is 60 to 90%.
As is clear from the following examples, the stretched resin sheet containing high-crystalline polypropylene, wherein the stretched resin sheet showing a high crystallinity of the polypropylene component in the stretched resin sheet is 60% or more, is high-crystal polypropylene. It exhibits excellent flame retardancy as compared with a stretched resin sheet which does not contain and exhibits a value in which the degree of crystallinity of the polypropylene component is low.
The detailed mechanism for improving the flame retardancy of the stretched resin sheet by containing high-crystal polypropylene in the propylene-based resin is unknown, but it is presumed as follows. A resin having a high degree of crystallinity requires an extra amount of heat to unravel the crystal portion as compared with a normal resin, so that the melting point and heat capacity become larger. Therefore, it has an effect of relatively preventing combustion, and it is considered that flame retardancy is exhibited by containing high crystalline polypropylene.
Generally, the crystallinity of polyethylene is higher than that of polypropylene. Therefore, the propylene-based resin composition was impregnated with an ethylene-based resin having a high degree of crystallinity, and the effect on the flame retardancy of the stretched resin sheet was confirmed. Even if a large amount of high crystallinity was contained and the crystallinity of the entire propylene resin composition was increased, the effect on the flame retardancy of the stretched resin sheet did not change.
On the other hand, as shown in the examples, if high crystalline polypropylene is contained in the propylene resin to increase the crystallinity of the polypropylene component of the stretched resin sheet, the flame retardancy of the stretched resin sheet can be improved.
Therefore, in the present invention, the crystallinity of the polypropylene component in the stretched resin sheet is defined.

The crystallinity of the polypropylene component in the stretched resin sheet is 60% or more, preferably 65% or more, more preferably 69% or more, still more preferably 74% or more. Further, the degree of crystallinity is usually 90% or less, although there is no particular upper limit.
When the crystallinity of the polypropylene component is within the above range, the stretched resin sheet can exhibit a higher flame-retardant effect.

<< Measurement method of crystallinity of polypropylene component in resin sheet >>
The crystallinity of the polypropylene component in the stretched resin sheet is measured by using an X-ray diffraction method.
Hereinafter, a method of measuring the crystallinity of the polypropylene component in the stretched resin sheet by using the X-ray diffraction method will be described in detail.
The measurement is performed using an X-ray diffractometer (for example, EMPYREAN manufactured by Spectris). By installing the measurement sample in an X-ray diffractometer and measuring the diffraction peak (diffraction profile) of the sample, the degree of crystallization is calculated from the ratio of the peak area of the crystal component to the total peak area.

[Manufacturing method of stretched resin sheet]
The method for producing a stretched resin sheet of the present invention uses a propylene-based resin composition containing a propylene-based resin and a flame-retardant as a starting material, forms the sheet by melt extrusion molding according to a conventional method, and then undergoes a stretching step. , Manufacture a stretched resin sheet.
Before performing melt extrusion molding, the propylene-based resin composition as a starting material may be pelletized into resin pellets containing propylene-based resin as a main component (hereinafter, also referred to as propylene-based resin pellets).
As a preferred embodiment of the method for producing a stretched resin sheet of the present invention, the following steps (I) to (III):
(I) Step of preparing propylene resin pellets,
(II) Melt extrusion molding process,
(III) Stretching step,
Examples thereof include a method for producing a stretched resin sheet containing.
The step of preparing the propylene-based resin pellets of (I) above is a kneading step of kneading a molding processing raw material composed of a propylene-based resin composition containing a resin component containing a propylene-based resin as a main component and a flame retardant. It refers to the process of producing granules (pellets) of the kneaded product that has passed through.
The melt extrusion molding step of the above (II) refers to a step of forming a non-stretched resin sheet by melt-kneading the pellets obtained in the above (I) and then extruding the kneaded product into a sheet shape.
The stretching step (III) described above refers to a step of stretching a non-stretched resin sheet in at least one axial direction.
Hereinafter, each step will be described in detail.

<Step (I): Step of preparing propylene resin pellets>
A molding processing raw material made of a propylene-based resin composition is kneaded to prepare a propylene-based resin pellet which is a kneaded product.
Each component and its content contained in the resin component containing the propylene-based resin as a main component, the flame retardant, and other propylene-based resin compositions constituting the propylene-based resin pellet are described in each item of the above [stretched resin sheet]. As explained in.

The propylene-based resin contained in the propylene-based resin pellets is a high-crystal polypropylene having a crystallinity of 51% or more and a general-purpose resin having a crystallinity of less than 51%, as described in the above << High-crystal polypropylene >>. Including with polypropylene. The content of high crystalline polypropylene in the propylene resin is as described in the column of << Highly crystalline polypropylene >> in the same.

As a preferred embodiment of the manufacturing process for preparing the propylene-based resin pellet of the above (I), for example, the manufacturing step of the following (I-i) can be mentioned.
(I-i) A propylene-based resin raw material is used as a main component, a flame retardant is blended, and melt-kneaded with an extrusion kneader (if the propylene-based resin contains other components other than these components, other components are used. (Knead together), extrude the obtained kneaded material into strands, cool it, and cut it with a cutter to prepare propylene-based resin pellets.

Further, in the above (I-i), when preparing the propylene-based resin raw material, high-crystal polypropylene may be prepared in advance and blended as in the manufacturing process described in the following (I-ii). ..
(I-ii) A propylene-based resin raw material blended with high-crystal polypropylene is used as the main component, a flame retardant is blended, melt-kneaded with an extrusion kneader, the obtained kneaded product is extruded into a strand shape, and then a cutter is used after cooling. To prepare propylene-based resin pellets by cutting with.

When the resin sheet has a multi-layer structure, propylene-based resin pellets for forming each layer corresponding to each layer may be prepared.
The heating temperature for melt-kneading is usually about 180 to 300 ° C as the cylinder temperature of the extruder, particularly about 200 to 250 ° C as the cylinder temperature in the compression zone, and the discharged resin temperature is usually about 200 to 250. ℃.

<Step (II): Melt extrusion molding step>
Next, the obtained resin pellets are melt-kneaded and then the kneaded product is extruded into a sheet to form an unstretched resin sheet.
As a preferred embodiment of the manufacturing step of the melt extrusion molding step of the above (II), for example, the manufacturing step of the following (II-i) can be mentioned.
(II-i) The obtained pellets are put into a feeder of an extruder, melt-kneaded, and then the kneaded material is extruded from the die to a T-die to obtain a sheet-like non-stretched resin sheet from the die. Discharge.

When the stretched resin sheet is a resin sheet having a multi-layer structure, a plurality of resin sheets can be formed by a coextrusion method using a multi-layer die using a feed block or a multi-manifold, an extrusion lamination method using a plurality of dies, or the like. A laminated multilayer resin sheet can be manufactured. Further, a resin sheet can be manufactured by a method of combining a coextrusion method using a multilayer die and an extrusion lamination method.

<(III) Step: Stretching Step>
The obtained unstretched resin sheet is stretched at least in the uniaxial direction using a roll, a tenter, or the like to prepare a stretched resin sheet.
Further, if necessary, an annealing treatment (heat treatment) may be performed, and then the selvage portion may be slit to obtain a stretched resin sheet.

The stretching of the resin sheet can be performed by various known methods. Specifically, a longitudinal stretching method using the difference in peripheral speed of the roll group, a transverse stretching method using a tenter oven, a sequential biaxial stretching method in which the longitudinal stretching and the transverse stretching are performed in forward or reverse order, a rolling method, and the like. Examples include a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor, a simultaneous biaxial stretching method using a combination of a tenter oven and a pantograph, and the like. Further, a simultaneous biaxial stretching method by a tubular method, which is a stretching method of an inflation film, can be mentioned.

The temperature at the time of stretching is not particularly limited, and the stretching can be carried out within a temperature range suitable for stretching the propylene-based resin. Specifically, it is preferable that the temperature is 2 to 15 ° C. or higher lower than the melting point of the propylene resin. For example, when the propylene-based resin composition contains an inorganic filler, the propylene-based resin composition is stretched at a temperature lower than the melting point of the propylene-based resin to form a stretched resin containing pores having an inorganic filler as a core. A sheet is obtained. In this case, the resin sheet is a sheet having appropriate opacity and light weight. Further, the stretching may be performed at a temperature equal to or higher than the glass transition temperature of the main propylene-based resin used for the resin sheet (mostly used in terms of mass ratio) and 1 to 70 ° C. lower than the melting point of the crystal portion of the propylene-based resin. It may be carried out in a temperature range of 1 ° C. lower to 2 ° C. higher than the melting point.

The draw ratio of the resin sheet is not particularly limited and may be appropriately determined in consideration of the characteristics of the obtained stretched resin sheet and the like. The draw ratio at the time of longitudinal uniaxial stretching is preferably larger than 2 times, more preferably 3 times or more, further preferably 4 times or more, preferably 10 times or less, and 8 times or less. Is more preferable, and 6 times or less is further preferable. Further, the stretching ratio at the time of lateral uniaxial stretching is preferably larger than 2 times, more preferably 4 times or more, further preferably 6 times or more, and preferably 20 times or less, 12 times. It is more preferably 2 times or less, and further preferably 10 times or less.
Further, in the case of stretching in the biaxial direction, the area stretching ratio (product of the vertical magnification and the horizontal magnification) is preferably 4 times or more, more preferably 10 times or more, and 20 times or more. It is more preferably 70 times or less, more preferably 60 times or less, and further preferably 50 times or less.

When the stretched resin sheet has a multi-layer structure, the number of stretched axes and the stretch ratio of the stretched resin sheets constituting each layer may be the same or different.

Hereinafter, a preferred method for producing a stretched resin sheet having a single-layer structure will be described.
First, the propylene-based resin composition is melt-kneaded by an extrusion kneader, the obtained kneaded product is extruded into a strand shape, cooled, and then cut with a cutter to prepare a propylene-based resin pellet. The obtained propylene-based resin pellets are put into a feeder of an extruder, melt-kneaded, and then the kneaded material is extruded into a T-die by an extruder, and a sheet-like unstretched resin sheet is discharged from the die. Is cooled to a temperature lower than the melting point of the propylene resin, for example, 40 to 85 ° C. in a cooling device to obtain a single-layer unstretched resin sheet. Next, this unstretched resin sheet is stretched 3 to 10 times in the longitudinal direction at a stretching temperature 2 to 15 ° C. or higher lower than the melting point of the propylene-based resin. As a result, a uniaxially stretched resin sheet oriented in the vertical direction can be obtained. Subsequently, this uniaxially stretched resin sheet is stretched 4 to 12 times in the lateral direction at a stretching temperature 2 ° C. to 15 ° C. or higher lower than the melting point of the propylene-based resin. As a result, a biaxially stretched resin sheet is obtained.

<Heat treatment>
It is preferable to heat-treat the stretched resin sheet. The temperature of the heat treatment is preferably 1 to 15 ° C. or higher higher than the melting point of the propylene resin. By performing the heat treatment, crystallization of the amorphous portion of the propylene-based resin is promoted, the heat shrinkage rate in the stretching direction is reduced, and the dimensional change of the resin sheet is reduced. The heat treatment method is generally performed by roll heating or a hot oven, but these may be combined.

<Surface treatment>
The stretched resin sheet may be surface-treated. By performing the surface treatment, the suitability for secondary processing of the stretched resin sheet can be improved. Examples of the surface treatment include corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, oxidation treatment such as ozone treatment, and the like. Further, the anchoring agent and the antistatic agent may be applied after the stretched resin sheet is subjected to an oxidation treatment.

[Use of stretched resin sheet]
The application of the stretched resin sheet of the present invention is not particularly limited, but it can be particularly suitably used for applications such as printing paper, label paper, and reflective sheet.
Examples of applications for printing include flame-retardant wallpaper used as a building material, flameproof posters used in stores, illuminated posters, pops, and the like. Examples of the use of the label or the seal include a store sticker used in a store, a tag label or harness used in an automobile or the like, a glass sticker used in a railway vehicle or the like, and the like. Applications that require a light reflection function include, for example, a light reflection sheet for a liquid crystal display, a light reflection sheet for an illuminated signboard, a light reflection sheet for indoor lighting, a multi-sheet for agriculture, a reflector for photography, and the back of a copy machine. Examples include lids.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as it does not exceed the scope of the technical idea.

<Example 1>
A general-purpose polypropylene which is a propylene homopolymer (trade name: Novatec PP FY6, manufactured by Japan Polypropylene Corporation) was prepared. The crystallinity of the propylene homopolymer: Novatec PP FY6 was 50.7% as a result of measurement by the DSC method.
High crystalline polypropylene (trade name: Novatec PP MA3U, manufactured by Japan Polypropylene Corporation) was prepared. The crystallinity of high crystalline polypropylene: Novatec PP MA3U was 57% as a result of measurement by the DSC method.
71.28 parts by mass of general-purpose polypropylene shown in Table 1, 12.5 parts by mass of high-crystal polypropylene, 10 parts by mass of high-density polyethylene (trade name: Novatec HP HJ381, manufactured by Nippon Polypro Co., Ltd.), represented by the formula (1). NOR type HALS compound having a chemical structure (trade name: Adecaster LA-81, manufactured by Adeca) 0.6 parts by mass, phosphorus compound (tris (2,4-di-tert-butylphenyl) phosphite (trade name:) Irgafos-168, manufactured by BASF Japan, Inc.) 0.62 parts by mass, and inorganic filler (rutyl type titanium dioxide fine powder (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.)) 5 parts by mass are mixed with a super mixer. Then, the polypropylene-based resin composition of Example 1 was obtained.
The obtained propylene-based resin composition is melt-kneaded in a twin-screw kneader set at 230 ° C., the kneaded product is extruded into a strand shape from a die, cooled in a water tank, and then cut with a pelletizer to be propylene-based. Resin pellets were obtained.

Next, the obtained pellets were melt-kneaded again using an extruder set at 230 ° C., the kneaded product was extruded into a sheet from a T-die, and the kneaded product was cooled to 60 ° C. by a cooling device to be cooled to 60 ° C. to form a single layer without stretching. A resin sheet was obtained.
Next, after heating this unstretched resin sheet to 143 ° C., a stretch ratio of 4.2 times in the transport direction (longitudinal direction) of the resin sheet is performed by a roll-to-roll stretching method utilizing the difference in peripheral speeds of a large number of roll groups. It was uniaxially stretched and then cooled at 60 ° C. to obtain a uniaxially stretched stretched resin sheet.

Next, the uniaxially stretched stretched resin sheet was reheated to 160 ° C. using a tenter oven, and 8.5 in the width direction (horizontal direction) of the stretched resin sheet by a clip stretching method using a tenter stretching machine. It was stretched at a double stretching ratio, and further subjected to an annealing treatment at 160 ° C. for 2 seconds in an oven while being held by a clip. After that, it was cooled to 60 ° C., the selvage portion was slit, and a single-layer stretched resin sheet sequentially biaxially stretched was obtained, and this was used as the stretched resin sheet of Example 1. The thickness of the stretched resin sheet of Example 1 was 100 μm. The transport speed of the sheet was controlled to 120 m / min.

The crystallinity of the polypropylene component in the above-mentioned propylene-based resin raw material and the stretched resin sheet was measured by the following measuring methods. The results are shown in Table 1.

<Measurement method of crystallinity of polypropylene component in propylene resin raw material>
By setting 10 g of propylene resin in a differential scanning calorimetry device and raising the temperature to 200 ° C at a temperature rise layer of 10 ° C / min, the relationship between the temperature [° C] and the heat of fusion [J / g] (DSC curve). ) Was obtained. The obtained DSC curve was compared with the DSC curve when the crystallinity was 100%, and the crystallinity of the propylene resin was calculated from the difference in the amount of heat of fusion [J / g].

<Measurement method of crystallinity of polypropylene component in stretched resin sheet>
The measurement was performed using an X-ray diffractometer (EMPYREAN manufactured by Spectris) having a rotating sample stage as an accessory device.
After cutting out the prepared stretched resin sheet to a size suitable for the sample holder and fixing it to the sample holder, diffraction profile measurement (total transmission measurement) by the wide-angle X-ray transmission method was performed at an output of 45 kV 40 mA while rotating the sample holder. The crystallinity was calculated. The X-ray source used is CuKα, and the detector is PIXcel ^3D .

The stretched resin sheet obtained above was evaluated for flame retardancy according to the following evaluation method and evaluation criteria.

<Flame retardance evaluation 1 (UL-94 VTM test)>
The flame retardancy of the stretched resin sheet obtained above was measured according to the UL94 VTM test.
Specifically, the obtained stretched resin sheet was cut into a short shape having a size of 50 mm × 200 mm to obtain a stretched resin sheet piece. The stretched resin sheet piece was allowed to stand for 48 hours or more under the condition of a temperature of 23 ° C. and a relative humidity of 50%. A marked line was marked at a position 125 mm from the lower end of the long side of the stretched resin sheet piece. Then, a tape was attached to a range of 125 mm to 200 mm from the lower end of the long side of the stretched resin sheet piece, and the short side was rolled and adhered so as to have a diameter of 13 mm to obtain a tubular stretched resin sheet piece. The obtained tubular stretched resin sheet piece was used as a test piece. The upper end of the test piece was clamped and hung, and 0.05 g or less of 100% cotton was placed at a position 300 mm below the lower end. Using a burner with a diameter of 10 mm, a blue flame of 105 mL / min and 20 mm was in contact with the flame so that the lower end of the test piece was located at a height of 10 mm from the tip of the flame. After flame contact for 3 seconds, whether the test piece melts to the marked line, the time t1 it took for the fire on the test piece to go out, and 100% cotton placed under the test piece burns. I confirmed whether it was or not. If the melting of the test piece does not reach the marked line in the first flame contact, the second flame contact is performed on the same test piece in the same manner as in the first time, and the same confirmation as in the first time (second contact). The time taken for the fire on the test piece to be extinguished by the flame is t2). The above-mentioned series of operations starting from cutting the resin sheet into a short shape was performed 5 times on the same resin sheet. These 5 times are regarded as one set.
The total time of t1 and t2 was defined as T1 and the total of 5 times (1 set) of T1 was defined as T2, and evaluated according to the following criteria.

<< Evaluation Criteria >>
A +: The melting of the test piece does not reach the marked line, both t1 and t2 are 3 seconds or less and T2 is 25 seconds or less, and the cotton placed under the test piece does not burn. A: The melting of the test piece is the mark. There is at least one sample that does not reach the line and is longer than 3 seconds at t1 and t2, and T2 is 25 seconds or less, and the cotton placed under the test piece does not burn. B +: The melting of the test piece is the marked line. There is at least one sample of t1 and t2 of 10 seconds or less, T2 of more than 25 seconds and 50 seconds or less, and t1 and t2 of 3 seconds or less, and cotton placed under the test piece. B: The melting of the test piece does not reach the marked line, t1 and t2 are both 10 seconds or less, T2 is larger than 25 seconds and 50 seconds or less, and the cotton placed under the test piece does not burn. B-: The melting of the test piece did not reach the marked line, t1 and t2 were both 10 seconds or less, T2 was larger than 25 seconds and 50 seconds or less, and the cotton placed under the test piece did not burn. , B-, because cotton burned in one of the five measurements, it was decided to remeasure an additional set according to VTM UL94.
C: The melting of the test piece does not reach the marked line, both t1 and t2 are 30 seconds or less and T2 is 250 seconds or less, and the cotton placed under the test piece does not burn. D: Melting of the test piece is the mark. The cotton placed under the test piece burns without reaching the line E: Melting of the test piece reaches the marked line (it is impossible even if the cotton does not burn)

The evaluation results of flame retardancy of the stretched resin sheet obtained above by the UL94 VTM test are shown in Table 1 below.

<Example 2>
In Example 1, the propylene-based resin pellets and the stretched resin sheet of Example 2 were obtained by the same procedure as in Example 1 except that the components constituting the propylene-based resin composition were changed to the ratios shown in Table 1. rice field.
Using the obtained stretched resin sheet, the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

<Comparative Example 1>
In Example 1, the propylene-based product of Comparative Example 1 was prepared by the same procedure as in Example 1 except that the components constituting the propylene-based resin composition were changed to the ratios shown in Table 1 without containing high-crystalline polypropylene. Resin pellets and stretched resin sheets were obtained.
Using the obtained stretched resin sheet, the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

<Example 3>
In Example 1, the propylene-based resin pellets and the stretched resin sheet of Example 3 were subjected to the same procedure as in Example 1 except that the components constituting the propylene-based resin composition were changed to the components and proportions shown in Table 2. Got
In Example 3, the phosphorus-based compound used in Example 1 was changed. In Example 3, bis (2,4-dicumylphenyl) pentaerythritol diphosphite (trade name: Doverfos S-9228, manufactured by Dover Chemical Co., Ltd.) was used as the phosphorus-based compound.
Using the obtained stretched resin sheet, the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 2.

<Examples 4 to 6>
In Example 3, the propylene-based resin pellets and stretched resin sheets of Examples 4 to 6 were subjected to the same procedure as in Example 3 except that the components constituting the propylene-based resin composition were changed to the ratios shown in Table 2. Got
Using each of the obtained stretched resin sheets, the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

<Comparative Example 2>
In Example 3, the propylene-based material of Comparative Example 2 was prepared by the same procedure as in Example 3 except that the components constituting the propylene-based resin composition were changed to the ratios shown in Table 2 without containing high-crystalline polypropylene. Resin pellets and stretched resin sheets were obtained.
Using the obtained stretched resin sheet, the same measurement and evaluation as in Example 3 were performed. The results are shown in Table 2.

In Tables 1 and 2, NOR-type HALS compounds, phosphorus compounds, and inorganic fillers are indicated by abbreviations. The NOR-type HALS compounds, phosphorus compounds, and inorganic fillers corresponding to each abbreviation are as follows.
LA81: Bis (1-undecaneoxy-2,2,6,6-tetramethylpiperidine-4-yl) carbonate (trade name: ADEKA STAB LA-81, manufactured by ADEKA CORPORATION)
S9228: Bis (2,4-dicumylphenyl) pentaerythritol diphosphite (trade name: Doverfos S-9228, manufactured by Dover Chemical)
Irg168: Tris (2,4-di-tert-butylphenyl) phosphite (trade name: Irgafos-168, manufactured by BASF Japan Ltd.)
TiO ₂ : Rutile type titanium dioxide fine powder (trade name: Typake CR-60, manufactured by Ishihara Sangyo Co., Ltd.)

From the evaluation results of the stretched resin sheets of Examples 1 to 6 and Comparative Examples 1 and 2, when high crystalline polypropylene is contained in the propylene resin, the crystallinity of the polypropylene component in the stretched resin sheet is increased to 60% or more. It was confirmed that the stretched resin sheet having a high degree of crystallinity of the polypropylene component exhibited excellent flame retardancy as compared with the stretched resin sheet containing no high crystallinity polypropylene.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin sheet exhibiting higher flame retardancy in a resin sheet obtained by molding a propylene-based resin composition containing a flame retardant.

Claims (11)

A stretched resin sheet containing a flame retardant and a resin component containing a propylene-based resin as a main component.
A stretched resin sheet, characterized in that the degree of crystallinity of the polypropylene component in the stretched resin sheet is 60 to 90%. The stretched resin sheet according to claim 1, wherein the flame retardant contains a NOR type HALS compound. The stretched resin sheet according to claim 2, wherein the flame retardant contains a NOR-type HALS compound and a phosphorus-based compound. The stretched resin sheet according to claim 2 or 3, wherein the content of the NOR-type HALS compound is 0.1 to 3 parts by mass with respect to 100 parts by mass of the resin component. The stretched resin sheet according to any one of claims 3 to 4, wherein the content of the phosphorus-based compound is 0.1 to 7 parts by mass with respect to 100 parts by mass of the resin component. The stretched resin sheet according to any one of claims 3 to 5, wherein the ratio of the content of the phosphorus-based compound to the content of the NOR-type HALS compound is 1 to 30 on a mass basis. The stretched resin sheet according to any one of claims 2 to 6, wherein the NOR-type HALS compound is a NOR-type HALS compound represented by the following formula (1).

A stretched resin that is formed into a sheet by melt extrusion using a propylene-based resin composition containing a flame retardant and a resin component containing a propylene-based resin as a main component, and then stretched to produce a stretched resin sheet. It ’s a sheet manufacturing method.
A method for producing a stretched resin sheet, wherein the propylene-based resin has a crystallinity of 51 to 55%. The method for producing a stretched resin sheet according to claim 8, wherein in the stretching step, the stretching of the resin sheet is biaxial stretching. The stretched resin sheet according to claim 9, wherein in the biaxial stretching, the stretching ratio in the longitudinal direction is greater than 2 times and 10 times or less, and the stretching ratio in the lateral direction is greater than 2 times and 20 times or less. Method. A resin pellet containing a flame retardant and a resin component containing a propylene-based resin as a main component.
A resin pellet characterized in that the crystallinity of the propylene-based resin is 51 to 55%.