JPH10147673A - Whitening-resistant transparent polyolefin resin composition and molded product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transparent polyolefin resin composition holding the suitable balance of flexibility, transparency, yield stress strength, scratch resistance (surface hardness), etc., and simultaneously exhibiting high heat resistance and whitening resistance, and to obtain a molded product using the composition. SOLUTION: This resin composition comprises a polypropylene resin (resin component A) exhibiting a melting point of >=125 deg.C measured with a differential scanning calorimeter at a temperature-rising rate of 10 deg.C/min and a hydrogenated block copolymer (resin component B) comprising (a) a polymer block of styrene or its derivative and (b) an isoprene polymer block or isoprene-butadiene copolymer block, wherein the total contact of 1, 2- and 3,4-bound isoprene units is >=25% based on the whole isoprene units and a resin component A/resin component B weight ratio is (85-45)/(20-55).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is suitable for materials such as film molded products, sheet molded products, hollow container molded products, and injection molded products which are excellent in transparency, whitening resistance upon impact and heat resistance. The present invention relates to a polyolefin-based resin composition and a film or sheet-like molded article using the same.

[0002]

2. Description of the Related Art A transparent polyolefin-based material is formed into various forms by taking advantage of its excellent workability, and is excellent as it is or by giving an arbitrary concavo-convex pattern on a part or all of its surface. As an article having a design effect, it is used in a wide range of fields, and the demand for packaging materials, general industrial containers, cosmetic containers, food containers, stationery, toys, video cassette cases, and the like is expanding. In particular, the transparent polyolefin-based material has a flexural modulus of 1000 to 1000.
Since it is as large as 7000 kgf / cm ^2, it is being replaced in a field where a transparent polyvinyl chloride resin has conventionally been used as a material having properties equal to or higher than that of the transparent polyvinyl chloride resin. Further, polyolefin-based materials do not generate corrosive gas during incineration treatment unlike vinyl chloride resins, have an advantage in this respect, and are widely used.

[0003]

However, in recent years,
As the application fields have expanded and the demand for improved design has increased, heat resistance, whitening resistance when subjected to impact, and high transparency have been demanded. The composition did not always meet these requirements. The present invention is a feature of a conventional transparent polyolefin resin composition, flexibility, transparency,
A transparent polyolefin resin composition which solves the above-mentioned problems and exhibits high heat resistance and whitening resistance while maintaining the yield stress strength, scratch resistance (surface hardness), etc. in an appropriate balance, and a composition using the same. It is an object of the present invention to provide a molded product in the form of a film or sheet.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned object, and as a result, have improved the problems relating to whitening resistance and transparency by using a specific polyolefin resin composition. The inventors have found that the present invention has been completed and completed the present invention. The whitening-resistant transparent polyolefin-based resin composition according to claim 1 has a heating rate of 10 ° C. by a differential scanning calorimeter.
/ Min, a polypropylene-based resin (resin component A) exhibiting a melting point of 125 ° C. or higher, a polymer block (a) of styrene or a derivative thereof, an isoprene polymer block or an isoprene / butadiene copolymer block Wherein the 1,2-position and 3,3 relative to all isoprene units
A hydrogenated block copolymer (resin component B) comprising a polymer or copolymer block (b) having a content of isoprene units bonded at the 4-position of 25% or more, and a resin component The weight ratio of A to resin component B is 80 to 45 /
20 to 55.

[0005] The whitening-resistant transparent polyolefin-based resin composition according to claim 2 comprises the resin component A, the resin component B,
It showed a melting point of 70 ° C. or more in a temperature rise analysis and a density of 0.92 g / cm ³
It contains the following ethylene-α-olefin copolymer resin (resin component C), and the weight ratio of the resin component A to the total amount of the resin component B and the resin component C is 80 to 45/20 to 55.
It is characterized by being. In the case of a resin composition containing both the resin component B and the resin component C, the weight ratio is preferably 10 to 40/90 to 60. The ethylene content of the resin component A is 3 to 10
Preferably it is mol%. The resin component C
Is preferably an ethylene-α-olefin copolymer having a melting point of 105 ° C. or higher in a temperature rise analysis and a density of 0.89 to 0.92 g / cm ³ . The molded article of the present invention is a film or sheet-shaped molded article obtained by extruding these polyolefin-based resin compositions.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The whitening-resistant transparent polyolefin resin composition of the present invention will be described in detail below. [Resin Component A] In the resin composition of the present invention, a polypropylene resin (referred to as “resin component A”) having a melting point of 125 ° C. or higher in a temperature rise analysis is an essential component. In the present invention, the temperature rise analysis means a differential scanning calorimeter (DSC).
Means a temperature rise analysis at a rate of 10 ° C./min. Examples of such a polypropylene-based resin include a homopolypropylene resin, a random copolymer of propylene and an α-olefin, and a binary or higher multicomponent copolymer of a block copolymer of propylene and an α-olefin. . Examples of the α-olefin include α-olefins having 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, such as ethylene, butene-1, and hexene-1. The resin component A mainly improves the yield stress, scratch resistance (surface hardness), and heat resistance of a molded article made of the resin composition of the present invention. In order to achieve these basic characteristics in the best balance, the resin component A
Among them, a random polypropylene resin having excellent compatibility with the resin components B and C described below and excellent transparency is preferable, and those having an ethylene content of 3 to 10 mol% are particularly preferable. If the ethylene content is less than 3 mol%, the transparency of the molded article may be insufficient,
If the ratio exceeds the above, a sticky feeling may be generated on the surface of the molded article.

Further, in the resin composition of the present invention,
Without impairing the above properties of resin component A as much as possible, resin component A alone has insufficient flexibility, transparency, feel, texture,
The resin component B or further the resin component C is added for the purpose of improving points such as whitening at the time of secondary processing involving sharp bending or when receiving an impact. Hereinafter, both resin components will be described.

[Resin component B] Resin component B used in the present invention
Is a polymer block of styrene or a derivative thereof (a)
And a specific isoprene polymer or a specific isoprene
Block (b) made of butadiene copolymer, and the block (b) is obtained by hydrogenation.
Since the resin component B does not contain a crystal part showing a distinct melting point,
An effect equivalent to that of the resin component C cannot be expected in properties relating to heat resistance. However, since the spherulite is finely dispersed in the resin component A to reduce the size of the spherulite, transparency and whitening resistance can be improved by adding a relatively small amount. Useful.

The polymer component constituting the block (a) is styrene or a derivative thereof. As the styrene derivative, specifically, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl- 4-benzylstyrene, 4- (phenylbutyl) styrene and the like. Among them, styrene and α-methylstyrene are preferred.

The polymer or copolymer constituting the block (b) is an isoprene polymer or an isoprene-butadiene copolymer, and is a 1,2-position and a 3,4-position with respect to the entire isoprene unit shown below. Content of isoprene units bonded at the position of at least 25%, preferably 30%
% Or more.

[0011]

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In the present invention, transparency and whitening resistance are particularly excellent when the content of isoprene units bonded at the 1,2-position and the 3,4-position relative to all isoprene units is 25% or more. A polyolefin-based resin composition can be obtained. The proportion of the polymer block (a) of styrene or its derivative in the resin component B is preferably 5 to 5
0% by weight, more preferably 10 to 45% by weight. That is, the ratio of the above-mentioned isoprene polymer block or isoprene-butadiene copolymer block (b) is preferably in the range of 95 to 50% by weight, more preferably 90 to 55% by weight. In the resin component B, it is desirable that at least 70% or more, preferably 80% or more of the block (b) is hydrogenated.
By using the hydrogenated resin component B, a polyolefin resin composition excellent in transparency, whitening resistance, and weather resistance can be obtained.

The resin component B used in the present invention has a melt flow rate (MFR: ASTM D 1238, 230 ° C., 2.16).
kg load) is preferably in the range of 0.1 to 30 g / 10 min, more preferably 0.5 to 20 g / 10 min.
By using the resin component B having a melt flow rate in the above range, a polyolefin resin composition having more excellent transparency and whitening resistance can be obtained. The block form of the resin component B used in the present invention includes a block (a)
-Block (b)-The form of block (a) is most preferred, but not limited thereto.

Such a resin component B can be obtained, for example, by hydrogenating a block copolymer obtained by the following method. (1) A method of sequentially polymerizing styrene or a derivative thereof, isoprene, or an isoprene-butadiene mixture using an alkyllithium compound as an initiator. (2) A method of polymerizing styrene or a derivative thereof, followed by isoprene or a mixture of isoprene and butadiene, and coupling the resulting mixture with a coupling agent. (3) A method of sequentially polymerizing isoprene or an isoprene-butadiene mixture, and then styrene or a derivative thereof using a dilithium compound as an initiator. Further details of the method for producing these block copolymers are described in, for example, JP-A-2-300250. When the block copolymer thus obtained is hydrogenated, the isoprene polymer block or the isoprene / butadiene copolymer block (b) is mainly hydrogenated to obtain a hydrogenated resin component B.

[Resin Component C] The resin composition obtained by mixing the resin component A and the resin component B described above is preferably further added with the resin component C. The resin component C is the same as the above D
In the temperature rise analysis of SC, it showed a melting point of 70 ° C. or more, and a density of 0.92 g / cm ³ or less, preferably 0.89 to 0.92 g / cm ^3.
Or a binary or multiple ethylene-α-olefin copolymer resin. As the α-olefin, propylene, butene-1, 4-methyl-pentene-1, hexene-1, and octene-1 are preferable. The resin component C is excellent in flexibility and excellent in compatibility with the resin component A, so that it is finely dispersed in the resin component A, does not impair transparency, and has a relatively high melting point. , The heat resistance is not significantly degraded. The above ethylene-α-
As the olefin copolymer resin, a resin having a melting point of 105 ° C. or more in a temperature rising analysis by DSC is particularly preferable.

The weight ratio of the resin component A to the resin component B, or the weight ratio of the resin component A to the resin component B and the resin component C can be arbitrarily set according to the use of the resin composition of the present invention. However, in order to obtain the effects of the present invention, the weight ratio of the resin component A / the resin component B or the resin component A / the resin component B and the resin component C is selected in the range of 80/20 to 45/55. There must be. 45% by weight of resin component A
If it is less than 125 ° C., the amount of the crystal component having a melting point of 125 ° C. or more decreases, and the heat resistance inherent to the resin component A is impaired. Further, since the amount of the resin component B or the amounts of the resin component B and the resin component C relatively increase, stickiness may occur on the surface. On the other hand, when the content of the resin component A exceeds 80% by weight, the amount of the resin component B or the amounts of the resin component B and the resin component C is relatively reduced, so that flexibility and transparency are insufficient.

Heat resistance of the transparent polyolefin material,
The addition of the resin component B to the resin component A is particularly effective in solving the problems such as whitening resistance and high transparency when subjected to an impact.
The heat resistance is further improved by further adding the resin component C thereto. Regarding the actual compounding, by making the amount of the resin component C larger than the amount of the resin component B, a resin composition having an excellent balance of various properties is often obtained.
According to the study of the present inventors, when both the resin component B and the resin component C are used, the most preferable effect is obtained when the weight ratio of the resin component B / the resin component C is in the range of 10/90 to 40/60. Is obtained.

The resin composition of the present invention may contain a nucleating agent in addition to the resin component A, the resin component C and the resin component B. The nucleating agent is used for improving transparency, rigidity, etc., and a sorbitol compound,
Metal salts of carboxylic acids, aromatic phosphate compounds,
Examples of the inorganic compound include silica and talc. Among these, aromatic phosphate compounds are preferred because of their remarkable effects of improving transparency and rigidity. These nucleating agents are added in an amount of 0.01 to 2 parts by weight per 100 parts by weight of the resin mixture.
Parts by weight, preferably 0.03 to 1 part by weight. 0.01
If the amount is less than part by weight, the transparency is not sufficiently improved, and if the amount exceeds 2 parts by weight, the effect of increasing the amount of addition is small, which is not only uneconomical but also has an adverse effect such as increased odor.

Further, in the resin composition of the present invention, an ethylene-α-olefin copolymer, an ethylene-propylene copolymer rubber, an ethylene-propylene-nonconjugated diene copolymer usually used for softening a polypropylene resin are used. A modifier such as rubber may be added within a range that does not impair the properties of the present invention. Depending on the application, antioxidants (eg, phenolic compounds, phosphorus compounds, sulfur compounds, etc.), weathering agents (eg, hindered amine compounds), lubricants (eg, higher fatty acid amides, fluororesins) , Metal soaps, etc.), additives such as anti-blocking agents (for example, silicic acids, carbonates, etc.), or a small amount of organic pigments or inorganic pigments for enhancing the effect of design, in a range that does not impair the properties of the present invention. May be added.

The resin composition of the present invention can be processed by a known method such as inflation molding, T-die molding, calender molding, hollow molding and injection molding. Examples of uses of the molded article made of the resin composition of the present invention include weather resistance,
It is suitable for fields where high performance is required for heat resistance and flexibility, and excellent transparency, design, feel, etc. are required. For example, packaging materials, general industrial containers, cosmetic containers, food containers, stationery, toys, video cassette cases, and the like can be exemplified. Further, at the time of molding, it is possible to further enhance the design effect by giving an arbitrary concavo-convex pattern on the whole or a part of the surface of the molded body. As the mold for shaping the pattern, any of a male / female mold for vacuum molding or air pressure molding, a mold for hollow molding, and a mold for injection molding can be used.

Further, the polyolefin resin composition of the present invention is particularly effective for a film-like or sheet-like (hereinafter simply referred to as "sheet-like") molded product. Such a sheet-like molded body can be produced by a usual molding method such as an inflation molding method, a T-die molding method, a calendar molding method, and a belt molding method, but it is particularly preferable to use extrusion molding. Among them, a forming method using a quenched chill roll by a T-die forming method is preferable in that high transparency, high productivity, and the like can be obtained.

The sheet-like molded article of the present invention is excellent in transparency, design, whitening resistance, molding workability during molding, and the like.
For example, by performing secondary processing such as thermoforming, containers such as food cups, lids, trays, blister packs, transparent files, stationery such as holders, bent products such as transparent cases such as confectionery and dolls, Alternatively, it can be widely used for PTP (press-through pack) containers for medicines, tablets, etc., and further for construction, civil engineering, industrial materials, and the like. The thickness of the sheet-shaped molded body varies depending on the purpose of use, application, and the like, but is generally 0.03 to 5 mm, preferably 0.05 to 3 mm,
More preferably, it is in the range of 0.1 to 2 mm.

[0023]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Various polyolefin-based resin compositions were prepared using the following components A and B.

(Component A) The component A used is the three types of polypropylene shown in Table 1.

[Table 1]

(Component B) The component B used is a copolymer of two types shown in Table 2.

[Table 2]

(Component C) The component C used is three kinds of linear low-density polyethylenes shown in Table 3.

[Table 3]

The preparation of each polyolefin resin composition is as follows:
The above components A to C are blended in the proportions shown in Tables 4 to 7,
0.1 parts by weight of a phosphorus-based antioxidant and 0.1 parts by weight of a phenol-based antioxidant are added to 100 parts by weight of each total resin, mixed with a Henschel mixer, and further mixed with a twin-screw continuous kneading extruder. This was performed by melt-kneading.

Using each of the obtained resin compositions, a sheet was formed by T-die molding and injection molding. Each manufacturing method is as follows. (1) Production of transparent sheet by T-die The resin composition was supplied to an extruder (40 mmφ, L / D = 22; full flight screw), and a hanger coat die of 600 mm width attached to the tip of the extruder was used. It was manufactured under the following conditions. Cylinder temperature: 230 ° C Die temperature: 230 ° C Lip gap: 0.8mm Air gap distance: 100mm Chill roll: 400mmφ, 30 ° C Final film thickness: 100μm / 150μm (2) Production of transparent sheet by injection molding It is as follows. Molding machine: IS-90B (manufactured by Toshiba Machine Co., Ltd.) Injection pressure: 800 to 1,000 kg / cm ² Molding temperature: 210 to 230 ° C. Mold temperature: 50 ° C. Molded body shape: 100 mm × 200 mm × 2 mm 100 mm × 100 mm × 1mm

Each of the obtained sheets was tested for transparency, whitening resistance and scratch resistance. The test method is as follows. (A) Transparency Test The haze of the transparent portion measured according to JIS K7105 and the unevenness of the transparency of the entire sheet by the naked eye were evaluated, and the relative evaluation was evaluated by the following four steps as a total evaluation. A: Very good. B: Excellent. C: Normal. D: Poor. (B) Whitening resistance test (1) Using a device specified in ASTM D1593-81 "Characteristics test on polyvinyl chloride sheet", the T-die sheet molded body was bent in a 5 ° C environment, and the sheet was subjected to bending. Was evaluated on the following three scales. A: No whitening is observed. B: Whitening is slightly observed. C: Whitening is clearly observed. (C) Whitening resistance test (2) (Surface impact test) A surface impact test (height: 80 cm, load: 1 kg, impact weight: 12.7 mmφ, cradle inner diameter: 43 mmφ) was performed on the injection molded body in an atmosphere of 23 ° C. Then, the whitening state of the sheet-like molded body was evaluated in three stages according to the same standard as in the above-mentioned whitening resistance test (1). (D) Scratch resistance test Using a JIS K5401 pencil scratch tester for coating film, a 50 g weight was placed on a weight base for the T-die sheet molded body.
The pencil hardness was measured, and the scratch resistance was evaluated.

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7] From Tables 4 to 7, it can be seen that a molded article using the resin composition of this example exhibits high-dimensional and well-balanced physical properties.

[0034]

The polyolefin resin composition of the present invention comprises (A) a polypropylene resin having a melting point of 125 ° C. or higher, (B) a polymer block (a) of styrene or a derivative thereof and an isoprene polymer block or (B) an isoprene-butadiene copolymer block, wherein the content of isoprene units linked at 1,2-position and 3,4-position to all isoprene units is 25% or more (b) Or a hydrogenated block copolymer comprising: (C) an ethylene-α-olefin copolymer resin having a melting point of 70 ° C. or higher and a density of 0.92 g / cm ³ or lower A molded article using the resin composition is excellent in various physical properties such as design properties, transparency, flexibility, scratch resistance, and whitening resistance. In particular, it has properties equal to or higher than that of a transparent polyvinyl chloride resin, and has no problem of corrosive gas generation during incineration treatment. Further, it is particularly suitable for application to a film-like or sheet-like molded product.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00

Claims (6)

[Claims] 1. A heating rate of 10 ° C. by a differential scanning calorimeter.
A polypropylene-based resin (resin component A) exhibiting a melting point of 125 ° C. or higher in a temperature rise analysis per minute, a polymer block (a) of styrene or a derivative thereof,
Isoprene polymer block or isoprene / butadiene copolymer block, wherein the content of isoprene units bonded at 1,2-position and 3,4-position to all isoprene units is 25% or more. A hydrogenated block copolymer (resin component B) comprising a polymer block (b), wherein the weight ratio of the resin component A to the resin component B is 80 to 45/20.
A whitening-resistant transparent polyolefin-based resin composition characterized by having a molecular weight of from 55 to 55. 2. A heating rate of 10 ° C. by a differential scanning calorimeter.
A polypropylene-based resin (resin component A) exhibiting a melting point of 125 ° C. or higher in a temperature rise analysis per minute, a polymer block (a) of styrene or a derivative thereof,
Isoprene polymer block or isoprene / butadiene copolymer block, wherein the content of isoprene units bonded at 1,2-position and 3,4-position to all isoprene units is 25% or more. A hydrogenated block copolymer (resin component B) composed of a polymer block (b), showing a melting point of 70 ° C. or more by temperature rise analysis, and a density of 0.92 g / cm ³
The following ethylene-α-olefin copolymer resin (resin component C) is contained, and the weight ratio of the resin component A to the total amount of the resin component B and the resin component C is 80 to 45/20 to 55. A whitening-resistant transparent polyolefin-based resin composition. 3. The resin component B and the resin component C have a weight ratio of 10
The whitening-resistant transparent polyolefin-based resin composition according to claim 2, wherein the ratio is from 40/90 to 60. 4. The resin component A having an ethylene content of 3 to 3.
The whitening-resistant transparent polyolefin-based resin composition according to any one of claims 1 to 3, which is 10 mol%. 5. The method according to claim 1, wherein said resin component C is 1
Shows a melting point above 05 ° C and has a density of 0.89-0.92 g / cm ³
The whitening-resistant transparent polyolefin-based resin composition according to any one of claims 2 to 4, wherein the ethylene-α-olefin copolymer is: 6. A film or sheet-like molded product obtained by extruding the polyolefin-based resin composition according to any one of claims 1 to 5.