TWI509005B - Film manufacturing method - Google Patents

Description

Film manufacturing method

The present invention relates to a method of producing a film.

In recent years, from the viewpoint of barrier free, etc., it is required that a film which is used as a material of a packaging material or the like has a property of being easily torn by a hand or the like (hereinafter referred to as "easy tearability"). . As such a film, for example, a multilayer film comprising a layer containing a cyclic olefin resin having a specific glass transition temperature or the like has been proposed (Patent Documents 1 and 2, etc.).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-224071

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2012-236382

However, the inventors of the present invention have found that it is impossible to obtain a film having a desired tearing property in accordance with the molding conditions.

The present invention has been made to solve the above problems, and an object thereof is to provide a method capable of producing a film having tearability.

The inventors have found that the resin composition is formed by using an extrusion machine. In the method for producing a film, the above problem can be solved by setting the difference between the glass transition temperature of the cyclic olefin resin in the resin composition and the cylinder temperature of the extruder to a predetermined value, and completed the present invention. Specifically, the present invention provides the following matters.

(1) A method for producing a film comprising the step of forming a film comprising a step of forming a resin composition containing a cyclic olefin resin of not more than 0% by mass and not more than 60% by mass and a non-cyclic olefin resin using an extruder The method wherein the cyclic olefin resin has a glass transition temperature of 40 ° C or higher and a value of 140 ° C or less after subtracting the glass transition temperature of the cyclic olefin resin from the cylinder temperature of the extrusion machine in the molding step.

(2) The method for producing a film according to (1), wherein the cyclic olefin resin has a glass transition temperature of 75 ° C or higher.

(3) The method for producing a film according to (1) or (2), wherein the non-cyclic olefin resin is selected from the group consisting of low density polyethylene, linear low density polyethylene, and polypropylene. More than one species.

(4) The method for producing a film according to the above aspect, wherein the cyclic olefin resin is contained in the resin composition in an amount of 20% by mass or less.

According to the present invention, it is possible to provide a method capable of producing a film having tearability.

Fig. 1 is a view showing the shape of a film obtained by the production method of the present invention. A diagram of an example.

Fig. 2 is a view showing a cross section of a film obtained by the production method of the present invention.

Fig. 3 is a view showing a cross section of a film obtained by the production method of the present invention.

Fig. 4 is a view showing the effect of the tear-off property of the film obtained by the production method of the present invention.

Hereinafter, embodiments of the present invention will be described. Further, the present invention is not limited by the following embodiments.

<Resin composition>

The resin composition of the present invention contains a cyclic olefin resin and a non-cyclic olefin resin. According to the results of studies by the inventors of the present invention, it has been found that in the molding step of the resin composition containing the cyclic olefin resin and the non-cyclic olefin resin, the cylinder temperature of the extruder is too high with respect to the glass transition temperature of the cyclic olefin resin. At the time, (specifically, when the value of the glass transition temperature of the cyclic olefin resin is reduced from the cylinder temperature of the extruder in the forming step to more than 140 ° C), the tear strength of the obtained film becomes high. And easy to tear. This is considered to be because the curing rate of the cyclic olefin resin and the non-cyclic olefin resin contained in the resin composition and the degree of restoration of the shape of each resin are different. In order to carry out a detailed study on such a situation, the inventors of the present invention conducted the following studies. In addition, hereinafter, the cyclic olefin resin is also referred to as "COC", and the glass transition temperature is also referred to as "Tg".

An extruder containing 20% by mass of a cyclic olefin copolymer (trade name "TOPAS 8007F-04", Tg = 78 ° C, Topas advanced Polymer) A resin composition of 80% by mass of a linear low-density polyethylene (LLDPE) was produced, and a film having the shape shown in Fig. 1 was produced, and its cross section was observed using a scanning electron microscope (SEM).

In addition, in order to clearly observe the region containing the cyclic olefin resin (hereinafter referred to as "COC region") of the produced film, the cross section of the film is subjected to any of the following two types of treatment, and then the film is observed by SEM. Profile. (Process 1) After the epoxy resin was buried, the film was sliced by a microtome. The cross section of the film observed by SEM is shown in Fig. 2(A). (Process 2) After the film was sliced by a microtome, epoxy resin was buried, and the cross section of the film was etched using tetrahydrofuran. By etching, the cyclic olefin resin in the film falls off, and the COC region can be hollowed out and visible. The cross section of the film observed by SEM is shown in Fig. 2(B).

As shown in Fig. 2(B), a film obtained from a resin composition containing a cyclic olefin resin and a non-cyclic olefin resin has a structure in which a COC region is dispersed in a matrix of a non-cyclic olefin resin.

In the treatment 1, since the etching was not performed, the cyclic olefin resin in the film did not fall off, and although the large cavity seen in Fig. 2(B) could not be observed, a small cavity having a crescent shape was observed (third The arrow of the figure). Further, Fig. 3 is an enlarged photograph of Fig. 2(A).

It is considered that the void of Fig. 3 is produced by the action shown in Fig. 4. That is, when the film is formed, the COC region is extended by being stretched from the mold of the extruder, and the formed film is cooled, and the temperature of the film is close to the glass transition temperature of the cyclic olefin resin. The shape of the COC region is solidified while being restored from the extended state. On the other hand, the acyclic olefin tree of the present invention When the curing of the grease (LLPDE or the like) occurs due to crystallization, the COC region is solidified by the decrease in temperature (that is, the temperature of the film is close to the glass transition temperature of the cyclic olefin resin). The curing system produces a delay in time. That is, the curing of the non-cyclic olefin resin (LLPDE or the like) and the curing of the COC region are deviated in timing. Therefore, during the recovery and solidification of the COC region, the elongation of the matrix of the non-cyclic olefin resin continues due to the drawdown. While the extension of the matrix of the acyclic olefin resin continues, the solidified COC region and the matrix of the non-cyclic olefin resin are peeled off and the interface (observable as the void shown by the arrow portion of Fig. 3) To). It is believed that such peeling and interfacial adhesions result in a reduction in the tear strength of the film (i.e., improved tearability).

In the present invention, the difference between the cylinder temperature of the extruder in the forming step and the glass transition temperature of the cyclic olefin resin in the resin composition is within a predetermined range (that is, from the extrusion machine in the forming step) The cylinder temperature is less than the glass transition temperature of the cyclic olefin resin and the value is 140 ° C or less. Thereby, the curing of the matrix of the non-cyclic olefin resin can advance the timing of curing of the COC region of the film which is hanged from the extruder, and the matrix of the COC region and the non-cyclic olefin resin can be made. The interface strength is lowered (in accordance with the case, peeling occurs between the COC region and the matrix of the non-cyclic olefin resin), and the tear strength of the film can be lowered.

(cyclic olefin resin)

The cyclic olefin resin of the present invention contains a cyclic olefin component as a copolymerization component, and is not particularly limited as long as it contains a polyolefin resin having a cyclic olefin component in its main chain. For example, examples of the cyclic olefin resin of the present invention include an addition polymer of a cyclic olefin or a hydrogen additive thereof, a cyclic olefin, and a cc-olefin. A co-polymer or a hydrogen additive thereof or the like. Further, in the above polymers, an unsaturated compound having a hydrophilic group may be grafted and/or copolymerized. As the cyclic olefin resin of the present invention, a commercially available resin (TOPAS (registered trademark) (manufactured by Topas Advanced Polymers Co., Ltd.) or the like) can also be used. These cyclic olefin resins may be used singly or in combination of plural kinds.

The glass transition temperature (hereinafter also referred to as "Tg") of the cyclic olefin resin of the present invention is 40 ° C or more, and the difference in cylinder temperature from the extruder of the film forming step can be 140 ° C. Adjust in the following ways. The Tg of the cyclic olefin resin can be specified by measurement according to JIS K7121 at a temperature increase rate of 10 ° C /min. When two or more kinds of cyclic olefin resins are used, the Tg system of the cyclic olefin resin can be specified by weighted average of each cyclic olefin resin.

Since the difference in cylinder temperature from the extruder is easily adjusted within a predetermined range, the Tg of the cyclic olefin resin is sufficient at 40 ° C or higher. When the Tg of the cyclic olefin resin is 75 ° C or higher, preferably 75 ° C or higher and 150 ° C or lower, more preferably 75 ° C or higher and 120 ° C or lower, the difference in cylinder temperature from the extruder becomes small because The formed film, the COC region and the matrix of the non-cyclic olefin resin are liable to cause peeling and interfaciality, and it is preferable to provide good tearability of the film.

In the resin composition, the cyclic olefin resin contains more than 0% by mass and 60% by mass or less. In such a range, a COC region can be formed in the matrix of the non-cyclic olefin resin in the formed film. In addition, the idea of ensuring the toughness of the film from the viewpoint of preventing the breakage of the bag is preferably 60% by mass or less. The cyclic olefin resin may be contained in the resin composition in an amount of 50% by mass or less, preferably 3% by mass or more and 45% by mass or less, more preferably 10% by mass or more and 40% by weight. Below mass%. In addition, even when the content of the cyclic olefin resin in the resin composition is 20% by mass or less, a sufficient effect can be exhibited.

(acyclic olefin resin)

The non-cyclic olefin resin of the present invention functions as a matrix resin in the formed film. The non-cyclic olefin resin of the present invention may be a matrix resin generally used as a film, and examples thereof include polyethylene, polyester, epoxy resin, polyamide, polypropylene, polyvinyl alcohol, and B. A resin such as vinylidene alcohol, polystyrene, vinyl chloride, polycarbonate, acrylic resin, ethylene vinyl acetate copolymer, polyphenylene sulfide, or polymethylpentene pentene.

As the non-cyclic olefin resin of the present invention, since peeling and an interface are likely to occur with the COC region, a polyethylene resin is preferred, and among the polyethylene resins, a low-density polyethylene (LDPE) is used, which is linear and low. One or more types of the group consisting of density polyethylene (LLDPE) and polypropylene (PP) are particularly preferable. These acyclic olefin resins are crystalline, and are harder to cure at the time of cooling than the cyclic olefin resin of the present invention. Further, in terms of easily providing tearability to the film, it is preferred to contain polypropylene as the non-cyclic olefin resin.

The melting point of the non-cyclic olefin resin of the present invention may be, for example, 60 ° C or more and 230 ° C or less. Further, the viscosity at the molding temperature (for example, 220 ° C) of the non-cyclic olefin resin of the present invention is 300 Pa at a shear rate of 60 sec ^-1 . Above s and 5000Pa. s below. It is preferred to use such a non-cyclic olefin resin insofar as it is easily formed into a film.

In the resin composition of the present invention, the non-cyclic olefin resin may be contained in an amount of 40% by mass or more, preferably 50% by mass or more, more preferably 55% by mass or more and 97% by mass or less, still more preferably 60% by mass or more and 90% by weight. Below mass%. The content of the non-cyclic olefin resin in the resin composition can be appropriately adjusted in accordance with the content of components other than the non-cyclic olefin resin.

(other ingredients)

In addition to the cyclic olefin resin and the non-cyclic olefin resin, the resin composition of the present invention may suitably contain a component which is usually used as a component of a film. Examples of such a component include an antioxidant, a secondary antioxidant, a colorant, a neutralizing agent, a dispersing agent, a photostabilizer, an ultraviolet absorber, a slip agent, an antistatic agent, an antifogging agent, a nucleating agent, and a pigment. Colorants, flame retardants, anti-adhesives, various other organic and inorganic compounds, and the like. The content of these components in the resin composition can be appropriately adjusted in accordance with the desired effect or the like.

(Method for producing resin composition)

In the method for producing the resin composition of the present invention, a conventionally known method for producing a resin composition can be used. For example, a melt kneading device such as a uniaxial or biaxial extruder can be used to melt the components. A method of obtaining a resin composition by pelletizing and extruding, and pelletizing. As another method, a mixture of resin pellets, powders, and the like which are blended at a ratio of each component of the resin composition of the present invention may be prepared and put into a film extruder.

<Method for Producing Film of the Present Invention>

The method for producing a film of the present invention comprises the step of forming the above-mentioned resin composition into a film using an extruder. In the forming step, the resin composition can be melted in the cylinder of the extruder in accordance with a normal extrusion shape, and then the mold of the extruder can be dropped in the air or water. The film was formed by cooling. The extruder used in the forming step is not particularly limited, and a uniaxial extruder, a twin-screw extruder, a screw extruder (full-screw type, A type such as a double spiral type or the like).

In the present invention, since the value after subtracting the glass transition temperature of the cyclic olefin resin from the cylinder temperature of the extruder in the molding step is 140 ° C or lower, the COC region can be formed in the matrix of the non-cyclic olefin resin. By the above action, the film can be provided with good tearability. The value obtained by subtracting the glass transition temperature of the cyclic olefin resin from the cylinder temperature of the extruder in the molding step may preferably be 130 ° C or lower, more preferably 50 ° C or higher and 130 ° C or lower. Further, generally, the temperature of the cylinder on the discharge side of the extruder is substantially the same as the temperature of the mold. Therefore, the "cylinder temperature of the extruder" in the present invention means the temperature of the cylinder and the mold on the discharge side of the extruder, which is substantially the same as the temperature of the resin discharged from the extruder. For the same value.

In the method for producing a film of the present invention, the film can be prepared as a single layer film or can be prepared as a multilayer film. When the film is prepared as a single layer film, the film formed by extrusion from the extruder can be used as it is. In this case, the amount of the cyclic olefin resin contained in the film may be more than 0% by mass and not more than 60% by mass, and may be, for example, 3% by mass or more and 45% by mass or less.

When the film is prepared as a multilayer film, a multilayer film obtained by forming a film obtained by the production method of the present invention as a sealing layer can be prepared by a conventional lamination method such as an extrusion coating method, a thermal build-up method or a dry build-up method. . In this case, the amount of the cyclic olefin resin contained in the film can be appropriately adjusted in accordance with the desired tearability. Specifically, in the case of the multilayer film, the amount of the cyclic olefin resin contained in the entire film structure may be more than 0% by mass and not more than 60% by mass, and may be 50% by mass or less, preferably 3% by mass. % or more and 45% by mass or less, more preferably 10% by mass or more and 40% by mass or less. In addition, even when the amount of the cyclic olefin resin in the entire structure of the multilayer film is 20% by mass or less, a sufficient effect can be exhibited.

In the method for producing a film of the present invention, the thickness of the film is not particularly limited. For example, any of the single-layer film and the multilayer film can be adjusted to 5 μm or more and 200 μm or less.

<Film obtained from the production method of the present invention>

The film obtained by the production method of the present invention is excellent in tearability. The tearability of the film obtained by the production method of the present invention can be specified by the Ermandorf tear test in accordance with JIS K7128 and JIS P8116. The lower the value obtained, the lower the tear strength and the more excellent the tearability. For example, the film obtained by the production method of the present invention has a strength of 5 to 350 g/16 pieces in the longitudinal cracking of the Elmandorf tear test. Further, the film obtained by the production method of the present invention has a strength of 10 to 400 g/16 pieces in the case of the transverse cracking of the Elmendorf tear test.

The film obtained by the production method of the present invention can be suitably used as a cover material, a label, or the like as various packaging materials and containers.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited thereto.

<Example 1 and Comparative Example 1>

Low-density polyethylene ("LDPE" in Table 1, trade name "NOVATEC LD LF640MA", manufactured by Japan POLYETHYLENE Co., Ltd.), and glass transition temperature (hereinafter, "Tg" in the table) are different cyclic olefin copolymers ("COC" in Table 1) was mixed at the ratio shown in Table 1, and the resin composition was obtained. The obtained resin composition was molded into a cast film (single layer) having a thickness of 30 μm using an extruder (this step corresponds to a "forming step"). The cylinder and mold temperature of the extruder in the forming step are as shown in Table 1.

In addition, in the following, the unit of the numerical value of the prescription in the table is "mass%." Further, "T(C+D)" means the temperature of the cylinder and the mold of the extruder in the forming step. The term "T(C+D)-Tg" refers to the value obtained by subtracting the Tg of COC from "T(C+D).

The COC used is as follows.

Product name "TOPAS 7010F-600", Tg=110°C, manufactured by Topas advanced Polymer

Product name "TOPAS 8007F-500", Tg=78°C, manufactured by Topas advanced Polymer

Product name "TOPAS 9903D-10", Tg=33°C, manufactured by Topas advanced Polymer

The molding conditions of the cast film are as follows.

[film making device]

Φ 32mm analytical extrusion device (manufactured by PLASTICS Institute of Engineering)

Use a 300 wide hanger pattern. The screw system uses L/D=30, a compression ratio of 3.0, and a uniform melting device at the front end.

[forming conditions]

Mold lip gap: 1.0mm

Film thickness: 30μm

Draw ratio (thickness ratio): 33.3

Air gap: about 40mm

Roller temperature: 50 ° C

Screw rotation number: 50rpm

Discharge volume: 5.5kg/h

Traction speed: 11.5m/min

Film thickness: 30μm

<Example 2 and Comparative Example 2>

In the same manner as in Example 1 and Comparative Example 1, except that the linear low-density polyethylene ("LLDPE" in Table 2, trade name "Evolue-SP2040", manufactured by Prime Polymer Co., Ltd.) was used instead of the low-density polyethylene. A cast film is obtained.

<Example 3 and Comparative Example 3>

A cast film was obtained in the same manner as in Example 1 and Comparative Example 1, except that polypropylene ("PP" in Table 3, trade name "NOVATEC PP FL02A", manufactured by Japan POLYETHYLENE Co., Ltd.) was used instead of low-density polyethylene.

<Example 4 and Comparative Example 4>

In addition to low-density polyethylene ("LDPE" in Table 4, trade name "NOVATEC LD LF640MA", manufactured by Japan POLYETHYLENE Co., Ltd.) and polypropylene ("PP" in Table 4, trade name "NOVATEC PP FL02A", Japan A cast film was obtained in the same manner as in Example 1 and Comparative Example 1 except that low density polyethylene was used in place of POLYETHYLENE.

<tear strength>

The cast film prepared in the above examples and comparative examples was subjected to a Friedmandorf tear test in accordance with JIS K7128 and JIS P 8116 to measure the tear strength of each cast film. The results are shown in Tables 1 to 4. In addition, the term "longitudinal" in the table means strong when the cast film is split in the longitudinal direction (MD direction). degree. Moreover, the "horizontal" means the strength when the cast film is split in the lateral direction (TD direction).

As shown in Tables 1 to 4, a resin composition containing no cyclic olefin resin can obtain only a film having a high tear strength, and a film excellent in tearing property cannot be obtained (Comparative Example 1-1, Comparative Example) 2-1, Comparative Example 3-1).

In addition, even if the resin composition containing a cyclic olefin resin does not satisfy the condition that the Tg of the cyclic olefin resin is 40° C. or higher and “T(C+D)-Tg” is 140° C. or less, it does not contain In the case of the resin composition of the cyclic olefin resin, although the tearability is good, sufficient tearability is not easily obtained (Comparative Examples 1-2 to 4, Comparative Examples 2-2 and 3, and Comparative Example 3-2). Comparative Examples 4-2 and 3).

On the other hand, when the resin composition containing the cyclic olefin resin is formed so as to satisfy the condition that the Tg of the cyclic olefin resin is 40° C. or higher and “T(C+D)-Tg” is 140° C. or lower, A film excellent in tearability (various examples) was obtained. In particular, when a cyclic olefin resin having a Tg of 110 ° C is used, it is excellent in tearability (Example 1-1, Example 2-1, Example 3-1, and Examples 4-1 to 3). In addition, when the non-cyclic olefin resin contained in the resin composition contains polypropylene, the tearability is particularly good (Example 3-1, Examples 4-1 to 3).

<Example 5 and Comparative Example 5>

The three-layer film was formed by blow molding, and the tearability of the film was further evaluated in the same manner as in the above Examples 1 to 4 and Comparative Examples 1 to 4.

Specifically, as the linear low-density polyethylene (LLDPE), the trade names "NOVATEC UF421" and NOVATEC UF321" (all manufactured by Japan POLYETHYLENE Co., Ltd.) are used, and the glass transition temperature is used (hereinafter, in Table 5). "Tg") is a cyclic olefin copolymer ("COC" in Table 5) which is a different type of the composition described in Table 5 and is formed into a layer of three layers (layer A to layer C). Forming (this step is equivalent to the "forming step"). The blending of LLD PE with COC is carried out using pellet blending. The cylinder and mold temperature of the extruder in the forming step are as shown in Table 5.

In addition, in the following, the unit of the numerical value of the prescription in Table 5, the mark of "T (C+D)" and "T (C+D)-Tg" is the same as Table 1 to Table 4. Further, the COC used is also the same as that of the user of the first embodiment.

The molding conditions of the blown film are as follows.

[film making device]

Blow Molding Machine: Three-layer blow molding (manufactured by TOMI Machinery Industries Co., Ltd.)

[forming conditions]

Cylinder temperature:

(inner and outer layers) 180 ° C (C1) → 190 ° C (C2) → 190 ° C (H) → 190 ° C (JC)

(intermediate layer) 210 ° C (C1) → 210 ° C (C2) → 190 ° C (H) → 190 ° C (JC)

Extrusion die temperature: 190 ° C (D1) → 190 ° C (D2) → 190 ° C (D3)

Expansion ratio: 2.0

Traction speed: 12.5m/min

Layer thickness ratio of three layers: outer (A) layer: middle (B) layer: inner (C) layer = 1:1:1

Film thickness: 50μm

Further, the layer-by-layer ratio of the three layers was 1:1:1, and the content of the cyclic polyolefin in the entire multilayer film was 3.3% by mass in Examples 5-1 and 5-2. -3, 5-4 was 6.7% by mass, and in Examples 5-5 and 5-6, it was about 17% by mass.

As shown in Table 5, in the blown film with LLDPE as the main component In the film-forming film, a resin composition containing no cyclic olefin resin can obtain only a film having a high tear strength, and a film excellent in tearing property cannot be obtained (Comparative Example 5).

In addition, when the resin composition of the cyclic olefin resin is contained in the intermediate layer to satisfy the conditions that the Tg of the cyclic olefin resin is 40° C. or higher and the “T(C+D)-Tg” is 140° C. or lower, A film excellent in tearability (each example of Example 5) was obtained. In particular, in addition to the fact that the higher the content of the cyclic olefin resin, the more excellent the tearability can be obtained, the cyclic olefin When the content of the resin is the same, when a cyclic olefin resin having a Tg of 110 ° C is used, the tearing property is excellent (Example 5-1, Example 5-3, and Example 5-5).

Claims (3)

A method for producing a film comprising a layer composed of a cyclic olefin resin of 10% by mass or more and 60% by mass or less and a resin composition of a non-cyclic olefin resin, and the above-mentioned ring in the entire layer in a plurality of layers a method for producing a film having a tearable property by stretching a mold of an extruder having a content of 3% by mass or more, which is formed by stretching from a mold of an extruder, and extending the film; the acyclic olefin The resin is selected from the group consisting of low density polyethylene, linear low density polyethylene, and polypropylene; the cyclic olefin resin has a glass transition temperature of 40 ° C or higher, and is extruded from the molding step. The cylinder temperature of the machine minus the glass transition temperature of the cyclic olefin resin is 140 ° C or lower, and the cross section of the film is observed by SEM, and the region of the cyclic olefin resin is dispersed in the acyclic olefin resin. In the matrix, there is a void at the interface between the above substrate and the above region. The method for producing a film according to claim 1, wherein the cyclic olefin resin has a glass transition temperature of 75 ° C or higher. The method for producing a film according to the first or second aspect of the invention, wherein the cyclic olefin resin is contained in the resin composition in an amount of 20% by mass or less.