JPH08225662A - Production of stretched resin film - Google Patents

Abstract

PURPOSE: To obtain a good-isotropy β-crystalline polypropylene synthetic paper for use in high-speed offset printing by crystallizing a film comprising a crystalline propylene polymer and a tetraoxaspiro compd. blended therewith as a nucleating agent at a specific temp. and then stretching it. CONSTITUTION: (A) 100 pts.wt. crystalline propylene polymer is blended with (B) 0.0001 to 5 pts.wt. tetraoxaspiro compd. of the formula I (wherein R<1> and R<2> are each H, 1-20C alkyl, 5-20C cycloalkyl, or the like), and melt-extruded to form a film, which is then crystallized at 10 to 140 deg.C to obtain a raw nonstretched film of a β-crystalline propylenic polymer, which is then stretched to obtain a synthetic paper. The component (A) may be either a propylene homopolymer or a propylene copolymer, the melt flow rate of which is pref. about 0.1 to 20g/10min. The component (B) is obtd. by amidation of a dicarboxylic acid of the formula II with cyclohexylamine or the like. The raw film pref. contains 40 to 70% β crystals. The stretching temp. is at least the m.p. of βcrystals and at most the m.p. of α crystals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a β-crystalline propylene polymer film. The surface-roughened film produced by the method is useful as writing paper, poster paper, and electric signboard paper.

[0002]

2. Description of the Related Art As a method for producing β crystal crystals in a raw (unstretched) propylene polymer film, a method of crystallizing a molten propylene polymer under a temperature gradient or a small amount of β crystal nucleating agent is used as propylene. A method of adding and mixing with a resin has been proposed.

However, the former has a drawback that it takes a long time and only a small amount of β crystal can be obtained. On the other hand, in the latter method, γ-quinacridone [PO
LYMER LETTERS, 6, 539-546 (1
968)] is famous, but when the nucleating agent is applied,
It has the drawback of requiring special equipment and operation in mixing with a propylene-based polymer. Further, in order to generate a certain amount or more of β-type crystals in the original film, it is necessary to crystallize the film at a high temperature, which requires a long time for molding, which makes it impractical. There is a problem that it is colored red.

Usually, the crystalline propylene polymer crystal has a monoclinic crystal α-crystal structure at a temperature of 160 ° C. to 174 ° C., but the temperature is 142 ° C. by adding a specific nucleating agent. It is announced that it forms a β-crystal structure with a hexagonal crystal lattice at 153 ° C. (R. J. Samuels, R.
Y. Ye-Author. J. POLYMER SCI. A-2,
10 , 385, 1972).

Further, a biaxially oriented film of polypropylene containing 5 to 40% by weight of inorganic fine powder is used as a base material layer in place of the natural pulp paper, and the front and back surfaces contain 8 to 65% by weight of inorganic fine powder. Synthetic paper using a uniaxially stretched multi-layered polypropylene film as a paper-like layer has been proposed and put into practical use. (U.S. Pat. No. 4,318,950, JP-B-46-40794, JP-B-60-36173.
(See Japanese Patent Publication No. 62-35412, etc.)

This synthetic paper having a laminated structure has a large number of fine voids (microvoids) around the inorganic fine powder as a core and a large number of elongated cracks on the surface. As a result, some of the inorganic fine powder that has become the core of fine voids and surface cracks protrude from the surface, and this inorganic fine powder falls off from the surface layer (so-called paper dust trouble).
The inorganic fine powder that has fallen off stains the blanket cylinder at the time of offset printing and mixes in the printing ink to reduce continuous printability, which is not preferable.

Particularly, in the case of synthetic paper in which the uniaxially stretched film constituting the surface layer contains more than 50% of inorganic fine powder or coarse inorganic fine powder having a powder diameter of more than 4 μm, Paper dust accumulates in a high-speed offset printing machine in a short time, and it is necessary to stop the printing machine frequently to clean the printing machine, resulting in extremely poor printing workability.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stretched resin film which has no troubles during printing, is excellent in writability, is free from red discoloration, and has many β crystals.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a tetraoxaspiro compound having a specific structure is β
It was found that the desired object can be achieved by crystallizing a melt formed by mixing a predetermined amount as a crystal nucleating agent at a predetermined temperature, and based on such findings, the present invention has been completed.

That is, the present invention provides a propylene-based polymer 10
10 to 140 resin films obtained by extruding a melt of a propylene-based polymer resin composition containing 0.0001 to 5 parts by weight of a tetraoxaspiro compound represented by the following general formula (1) per 0 weight. A method for producing a β-crystalline propylene-based polymer stretched film, which comprises crystallization at ℃ to obtain a β-crystalline propylene-based polymer unstretched film, and then stretching this at a temperature lower than the melting point of the propylene-based polymer. , Is provided.

[0011]

Embedded image [In the formula, R ¹ and R ² may be the same or different,
Hydrogen atom, alkyl group having 1 to 20 carbon atoms, 5 to 5 carbon atoms
20 cycloalkyl groups or C6-C20 ary-
Group, or R ¹ and R ² are each ω
-Ends are bonded to each other and jointly represent an alkylene group having 4 to 7 carbon atoms. ]

The propylene-based polymer according to the present invention is a polymer having propylene as a main constituent component. Specifically, it is mainly composed of propylene homopolymer, propylene, and 1-alkene (ethylene, 1-butene, 1-
(Pentene, 1-hexene, 4-methylpentene-1, etc.)
And a copolymer of propylene and a monomer such as styrene, maleic anhydride, or (meth) acrylic acid. Further, a polymer containing the propylene-based polymer as a main component and a small amount of a thermoplastic resin, for example, high density polyethylene, polybutene-1, poly-4-methylpentene-1 or the like, may be exemplified.

Such propylene-based polymers include not only commonly used Ziegler-Natta type catalysts but also propylene-based polymers obtained by polymerization in the presence of a highly stereoregular catalyst. Examples of such highly stereoregular catalysts include transition metal compounds (for example, titanium trioxide,
A catalyst in which a titanium halide such as titanium tetrachloride is supported on a carrier containing magnesium halide (eg, magnesium chloride) as a main component and an organoaluminum compound (triethylaluminum, diethylaluminum chloride, etc.) in combination. And a catalyst system consisting of

Examples of the polymerization method include various methods such as a slurry polymerization method using a hydrocarbon such as hexane and heptane as a solvent, a bulk polymerization method using liquid propylene as a solvent, and a gas phase method. The crystallinity of the crystalline propylene-based polymer thus obtained is usually 20 to 70%.

The propylene polymer has a melt flow rate (MFR: JIS K-7210) of 0.1 to 20 g.
The range of about / 10 minutes is preferable in terms of physical properties such as mechanical properties of the film and processability. The tetraoxaspiro compound represented by the general formula (1) can be prepared by amidating a dicarboxylic acid represented by the following general formula (2) with a predetermined monoamine.

[0016]

Embedded image

Examples of the monoamine include cyclohexylamine, 4-t-butylcyclohexylamine, 2,
4-di-t-butylcyclohexylamine, 1-adamantylamine, aniline, 4-t-butylaniline,
2,4-di-t-butylaniline, 1-naphthylamine, n-butylamine, n-hexylamine, n-dodecylamine, n-octadecylamine, ammonia, dicyclohexylamine, diphenylamine, N- (n-
Butyl) cyclohexylamine, N- (n-butyl) aniline, pyrrolidine, piperidine and the like.

Particularly preferred representative examples of the tetraoxaspiro compound represented by the general formula (1) of the present invention are as follows. Note that these compounds will be referred to by the compound numbers below.

(Compound No. 1) 3,9-bis [4- (N
-Cyclohexylcarbamoyl) phenyl] -2,4
8,10-Tetraoxaspiro [5,5] undecane (Compound No. 2) 3,9-bis {4- [N- (4-t-
Butylcyclohexyl) carbamoyl] phenyl}-
2,4,8,10-Tetraoxaspiro [5,5] undecane (Compound No. 3) 3,9-bis {4- [N- (2,4-
Di-t-butylcyclohexyl) carbamoyl] phenyl} -2,4,8,10-tetraoxaspiro [5
5] Undecane

The amount of the tetraoxaspiro compound compounded is 0.00 based on 100 parts by weight of the propylene polymer.
The amount is 01 to 5 parts by weight, preferably 0.001 to 1 part by weight. If it is less than 0.0001 parts by weight, β-type crystals are difficult to form, and if it is contained in excess of 5 parts by weight, no significant difference in effect is observed, and the breaking elongation and breaking strength of the resin film decrease. There are drawbacks. The propylene polymer resin composition is usually melt-kneaded at about 190 to 300 ° C. using an extruder, extruded into a film, cooled to a crystallization temperature, and stretched.

The crystallization temperature of the resin melt in the method of the present invention is 10 to 140 ° C., preferably 20 to 120.
℃ is recommended. If the crystallization temperature is lower than 10 ° C., the β-type crystal content is low, and a sufficiently roughened film cannot be obtained even if the original film is stretched by the method described later.
Further, at 140 ° C. or higher, the time required for crystallization is long and not practical. In the unstretched raw film that has been cooled and crystallized at the above temperature, 2% as measured by the DSC method described later.
The β crystal is contained in a ratio of 0 to 80%, preferably 40 to 70%.

The stretching method may be uniaxial stretching and simultaneous or sequential biaxial stretching. The draw ratio is 3.5 to 12 times in the machine direction and the transverse direction. The stretching temperature is higher than the melting point of the β crystal of the crystalline propylene polymer and lower than the melting point of the α crystal. The stretched propylene polymer film thus obtained has a surface smoothness (JISP8119) of 50.
Since it is a semi-transparent or opaque surface roughened film which has an opacity of 20 to 65% at 0 to 3500 seconds and is excellent in drawing property, printability and writing property, it is a printing paper or a training paper. Widely used as label paper, heat-sensitive base paper, and food packaging film.

In producing the surface-roughened film according to the present invention, various additives such as stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, antiblocking agents, lubricants and inorganic fillers are added, if necessary. Can be used together within a range that does not impair the effects of the present invention. Further, the stretched film surface is subjected to corona discharge treatment in order to improve the fusset printability, polyethyleneimine, poly (ethyleneimine-urea), an ethyleneimine adduct of polyamine polyamide, an epichlorohydrin adduct of polyamine polyamide, and A water-soluble primer selected from the group consisting of quaternary or quaternary nitrogen-containing acrylic resins may be applied.

[0024]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The β-type crystal content, opacity, writability and printability were determined by the following methods. [Measurement of β-type crystal content rate] DSC method: About 5 mg of a propylene-based polymer raw film was set in a DSC sample holder, and under a nitrogen atmosphere, 1
The temperature was raised at 0 ° C./min, and the β-type crystal content (area%) was calculated from the α-type crystal area (B) and the melting peak area (A) of the β-type crystal of the thermogram obtained at this time as follows. Calculate using a mathematical formula.

[0025]

[Equation 1]

Incidentally, A and B of the propylene homopolymer used in the examples are as follows. A: β crystal area (area surrounded by melting point peak between 142 ° C. and 153 ° C.) B: α crystal area (area surrounded by melting point peak between 160 ° C. and 174 ° C.) DSC: Scanning calorimeter SSC-5200 thermal analysis system (trade name) [manufactured by Seiko Denshi Kogyo KK]

[Measurement of Opacity] The opacity of the stretched film was measured by an SM color computer (manufactured by Suga Test Instruments Co., Ltd.) according to "JIS P8138". [Surface smoothness] According to “JIS P8119”.

[Writability] Using a pencil hardness tester (scratch tester) manufactured by Toyo Seiki Co., Ltd., a pencil of hardness HB set so as to be perpendicular to the obtained stretched resin film is loaded with a load of 200 g. And draw a line segment at a speed of 200 seconds / m. This line segment was visually observed and judged as follows. ○: Can be read clearly. B: Written but thin and a little difficult to read. X: Almost not written.

[Printability] The stretched resin film is cut into A4 size, and the offset ink "L" manufactured by Toyo Ink Co., Ltd.
-Katon "(trade name) and a small offset printing machine" Hamada 612CD "(trade name) were used for two-color printing. After printing, microscope with national light [Matsushita Electric Industrial Co., Ltd.
Manufactured by K.K.] was used to observe the ink points printed on the stretched resin film, and the printability was determined as follows. ○: The points can be clearly read. Δ: The edge portion of the halftone dot is thin and difficult to read. X: The whole halftone dot is thin and difficult to read, or unreadable.

Example 1 A propylene homopolymer having a MFR of 4.3 g / 10 min (DSC peak temperature: 165.3).
C., melting end temperature 176.degree. C.) 3,9-bis [4- (N-cyclohexylcarbamoyl) phenyl] -2,4,8,10 as a β crystal nucleating agent per 100 parts by weight of powder.
-0.05 parts by weight of tetraoxaspiro [5,5] undecane (Compound No. 1) was mixed and mixed in a Henschel mixer, and extruded in a strand form from a die at 240 ° C, and cut into pellets. Then, it was extruded into a sheet at a resin temperature of 240 ° C. using a T-die extruder, cooled and solidified by a chill roll maintained at 70 ° C., and had a thickness of 750 μm.
A propylene polymer original film of m was obtained. The content of β-type crystals in the obtained unstretched film was 65% as measured by the DSC method, and the surface smoothness was 10,400 seconds. (I couldn't write a pencil on this one.)

Next, this film was stretched 5 times in the machine direction at 153 ° C. by a heating roll stretching machine, and then,
This longitudinally stretched film was heated by an air-heated horizontal stretching machine to
It was stretched 5 times at 5 ° C. to obtain a biaxially stretched film having a thickness of 25 μm. The opacity of this film was 53%, the surface was sufficiently roughened, and the film was an opaque white film excellent in writability and printability.

Example 2 Pellets were pelletized in the same manner as in Example 1 except that 0.2 part by weight of Compound No. 1 was blended as a β crystal nucleating agent, and then the raw material was fed into the extruder used in Example 1. It was supplied and cooled and solidified by a chill roll maintained at 50 ° C. to obtain an unstretched film. The content of β-type crystals in the obtained unstretched film was 60% as measured by the DSC method. Then, as in Example 1, the film was stretched to have an opacity of 50%.
To obtain a stretched film.

(Example 3) 3,9-bis {4- [N- (4-t-butylcyclohexyl) carbamoyl] phenyl} -2,4,8,10-tetraoxaspiro [5] as a β crystal nucleating agent , 5] Undecane (Compound No. 2) was added to 0.0
A film was prepared in the same manner as in Example 1 except that 5 parts by weight was blended. The content of β-type crystals in the obtained unstretched film was 62% as measured by the DSC method. The opacity of this film was 53%, the surface was sufficiently roughened, and the film was an opaque white film excellent in writability and printability. Then, the film was biaxially stretched in the same manner as in Example 1 to obtain a film having a thickness of 25 μm. The opacity of this film was 50%, the surface was sufficiently roughened, and the film was an opaque white film excellent in writability and printability.

Comparative Example 1 A biaxially stretched film was obtained in the same manner as in Example 3 except that 0.05 part by weight of γ-quinacridone was blended as a β crystal nucleating agent. The content of β-type crystals in the unstretched film obtained at this time was 12% as measured by the DSC method.
Met. The biaxially stretched film thus obtained had an opacity of 5%, had insufficient surface roughening, and was colored red. The film was an opaque white film excellent in writability and printability.

Comparative Example 2 A biaxially stretched film was obtained in the same manner as in Example 3 without using the β crystal nucleating agent. The content of β-type crystals in the unstretched film obtained at this time was D
It was 0% as measured by SC method, the opacity of the biaxially stretched film obtained from this was 1%, and the surface of the transparent film was smooth.

Example 4 As a β crystal nucleating agent, 3,9-bis {4- [N- (2,4-di-t-butylcyclohexyl) carbamoyl] phenyl} -2,4,8,10- 0.1 parts by weight of tetraoxaspiro [5,5] undecane (Compound No. 3), 95 parts by weight of propylene polymer,
A film was prepared in the same manner as in Example 1 except that 5 parts by weight of high density polyethylene was applied. The content of β-type crystals in the obtained unstretched film was 45% as measured by the DSC method. The opacity of this film was 38%.

Then, the film was biaxially stretched in the same manner as in Example 1 to obtain a film having a thickness of 25 μm. The opacity of this film was 35%, the surface was sufficiently roughened, and the film was an opaque white film excellent in writability and printability. The stretched films obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0038]

[Table 1]

For reference, the DSC curve (1) of the propylene homopolymer used in Example 1 and 0.0 parts of the β crystal nucleating agent of Compound No. 1 in 100 parts by weight of this propylene homopolymer.
The DSC curve (2) of the composition containing 5 parts by weight is shown in FIG. FIG. 1 shows that the melting point peak of the propylene homopolymer moved to the low temperature side by the addition of the β crystal nucleating agent.

[0040]

EFFECT OF THE INVENTION A propylene-based polymer film containing a tetraoxaspiro compound as a β-crystal nucleating agent is capable of high-speed molding at a relatively low temperature, and a β-crystal propylene-based polymer stretched film obtained by stretching the film. Is a semi-transparent or opaque stretched film having a roughened surface, and has excellent pencil writing and printability.

[Brief description of drawings]

1 is a DSC curve (2) of a composition prepared by blending a propylene homopolymer used in Example 1 and Comparative Example 2 with a β crystal nucleating agent.
FIG. 3 is a diagram showing a DSC curve (1) of a propylene homopolymer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 23/12 C08L 23/12 // B29K 23:00 B29L 7:00 (72) Inventor Kazu Hayama Hide 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd. In Yokkaichi Research Institute (72) Inventor Mitsumasa Minato 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd.

Claims (3)

[Claims] 1. A propylene-based polymer resin composition containing 0.0001 to 5 parts by weight of a tetraoxaspiro compound represented by the following general formula (1) per 100 parts by weight of a crystalline propylene-based polymer. A method for producing a stretched film of a β-crystalline propylene polymer, which comprises crystallizing a resin film obtained by extrusion of a melt at 10 to 140 ° C. to obtain a β-crystalline propylene polymer unstretched film, and then stretching. . Embedded image [In the formula, R ¹ and R ² may be the same or different,
Hydrogen atom, alkyl group having 1 to 20 carbon atoms, 5 to 5 carbon atoms
20 cycloalkyl groups or C6-C20 ary-
Group, or R ¹ and R ² are each ω
-Ends are bonded to each other and jointly represent an alkylene group having 4 to 7 carbon atoms. ] 2. The method for producing a stretched β-crystalline propylene polymer film according to claim 1, wherein the stretching is performed at a temperature higher than the melting point of the crystalline β of the crystalline propylene polymer and lower than the melting point of the crystalline α. 3. The Beck smoothness of the surface of the stretched film is 50.
0 to 3500 seconds, and the opacity of the stretched film is 20.
The method for producing a stretched film according to claim 1, wherein the stretched film has a content of ˜65%.