JP7018173B2 - Easy-to-peel film - Google Patents

Description

The present invention relates to an easily peelable film containing at least four or more layers of a base material layer, an anchor coating agent layer, a heat seal layer, and an antistatic agent layer containing a specific polymer type antistatic agent.

Conventionally, plastic containers such as polyethylene, polypropylene, and polystyrene and paper containers mainly made of paper have been used for food packaging and packaging of industrial parts. As the lid material of the paper container, an easily peelable film having an appropriate peeling strength and exhibiting smooth peeling performance at the time of peeling is used. Among them, the cover material for food containers made of paper and the cover tape for carrier tapes for transporting electronic components are required to have not only peeling strength but also a peeling appearance without so-called peeling, in which the paper of the container peels and fluffs at the time of peeling. To. When the cover tape of the carrier tape for transporting electronic components is peeled off from the paper carrier tape, if the peel strength is too high or the peel strength fluctuates greatly, peeling vibration (chatter) occurs and holes in the paper carrier are generated. Since the electronic parts and IC chips inside are tilted or popped out, and the electronic parts are not taken out properly due to the occurrence of paper peeling, it is required to maintain an appropriate peeling strength that does not peel off due to the external force applied during transportation.

In addition, when the electronic component is a component such as an IC that is easily dielectrically broken down by static electricity, the cover tape is charged with electrons when preventing dust from adhering, protecting the contents from static electricity, or peeling the cover tape from the paper carrier tape. In order to prevent troubles such as parts sticking and popping out, an antistatic agent is kneaded into the heat seal layer of the cover tape, and the surface of the heat seal layer is subjected to antistatic treatment.

In recent years, after electronic components are inserted into carrier tapes for transporting electronic components, they are increasingly transported to various countries for use, and they tend to be exposed to harsher environments and have longer transportation and storage periods. .. Therefore, it is desired to maintain the initial peel strength without changing the peel strength even in various environments. In addition, due to the miniaturization of electronic components, problems such as popping out of electronic components due to peeling vibration occur even if the peeling strength increases to a extent that has not been a problem in the past, and the demand for maintaining the peeling strength has increased. There is.

Similarly, with regard to antistatic properties, in addition to the increase in adhesion problems due to exposure to harsher environments than before and deterioration of antistatic effects due to prolonged transportation and storage periods. Due to the miniaturization of electronic components, the stability of antistatic effect is also required more than ever.

For the antistatic treatment, a method such as kneading an antistatic agent into a resin constituting a surface to be imparted with antistatic properties or applying a thin layer of the antistatic agent to the surface is used. Those coated with an antistatic agent on the surface of the adhesive layer are disclosed in, for example, Patent Documents 1 and 2. In order to obtain a sufficient antistatic effect by these methods, it is necessary to apply a large amount of antistatic agent, and the sealing strength to the carrier tape tends to be unstable. Further, it has been pointed out that the antistatic performance may be deteriorated by storing the product in a high temperature environment or a high temperature and high humidity environment for a long period of time.

In view of the above background, in addition to excellent heat-sealing properties and no fluffing of the paper carrier tape during peeling, the change in peel strength over time is small even when stored in a high temperature environment or a high temperature and high humidity environment. There has been a long-cherished desire for an easily peelable film having excellent retention of peeling characteristics and sustainability of antistatic effect.

Japanese Patent No. 2901857 Japanese Unexamined Patent Publication No. 5-51053

However, none of the above methods is satisfactory for heat-sealing properties and prevention of fluffing for paper containers, especially paper carrier tapes made of paper base materials, and in addition, they are in a high temperature environment or a high temperature and high humidity environment. Since the peeling strength is greatly increased when stored underneath, the peeling strength and the maintainability of the antistatic effect were not fully satisfied.

The present invention maintains the antistatic effect even when stored in a high temperature environment or a high temperature and high humidity environment, and maintains the initial peeling strength even when stored in a high temperature environment or a high temperature and high humidity environment after being bonded to the paper carrier tape. It is an object of the present invention to provide an easily peelable film having excellent maintainability of peeling characteristics to be maintained.

Therefore, as a result of diligent studies on the above problems, the present inventors have made a film structure containing at least four specific layers, and the easily peelable film containing a specific polymer-type antistatic agent in the antistatic agent layer has a high temperature. Excellent antistatic effect even when stored in an environment of high temperature and humidity, and maintains initial peeling strength even when stored in a high temperature environment or high temperature and humidity environment after bonding. We found that and came to complete the present invention.

That is, the present invention is a film including at least four layers of a base material layer, an anchor coat layer, a heat seal layer, and an antistatic agent layer, and the antistatic agent layer is a specific polymer type antistatic agent (A). The present invention relates to an easily peelable film characterized by containing.

Further, the present invention relates to a cover tape for a paper carrier tape used for transporting electronic components made of the easily peelable film.

The easily peelable film of the present invention maintains the antistatic effect even when stored in a high temperature environment or a high temperature and high humidity environment, and the initial peeling strength even when stored in a high temperature environment or a high temperature and high humidity environment after bonding. Excellent maintainability of peeling characteristics.

The present invention will be described in detail below.

The easily peelable film of the present invention is a film containing at least four layers of a substrate layer, an anchor coat layer, a heat seal layer and an antistatic agent layer in this order, and the antistatic agent layers are described below (a) to (c). The present invention relates to an easily peelable film, which comprises a cationic acrylic resin-based polymer type antistatic agent (A) satisfying the above requirements.
(A) Contains a methacrylic ester monomer residue unit.
(B) Have at least a quaternary ammonium salt in the side chain.
(C) The weight average molecular weight is 20,000 to 100,000.

The base material layer of the easily peelable film of the present invention is made of a thermoplastic resin, for example, a film formed from a thermoplastic resin such as polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefin such as polypropylene, and polyamide such as nylon. In particular, a biaxially stretched film can be preferably used. A biaxially stretched polyethylene terephthalate film is preferable, and a commercially available film can be used in either case. The surface to be adhered to the anchor coat layer is preferably corona-treated in order to strengthen the adhesive strength. The thickness of the base material layer is preferably 12 to 30 μm for rigidity and prevention of breakage.

As the anchor coat layer of the easily peelable film of the present invention, any one belonging to the category of the anchor coat agent can be used, and the adhesiveness between the base material layer and the heat seal layer or the intermediate layer is imparted. Anything that does is fine. Examples of the anchor coating agent include isocyanate-based, polyurethane-based, polyethyleneimine-based, and polybutadiene-based. As the coating amount, 10 to 200 mg / m ² as the solid content of the anchor coating agent is preferable, and 10 to 50 mg / m ² is more preferable because the antistatic performance does not deteriorate with time.

The heat-sealing layer of the easily peelable film of the present invention is a thermoplastic resin that has heat-sealing properties with respect to paper carrier tape, has excellent peeling appearance, and can be easily peeled off with appropriate peeling strength at the time of peeling. It may be composed of. Among them, a composition containing an ethylene-vinyl acetate copolymer and a tackifier is preferable, and the vinyl acetate content measured by JIS K6924-1 is in the range of 3 to 18% by weight, and is measured by JIS K6924-1. An ethylene-vinyl acetate copolymer (C) with a melt mass flow rate in the range of 5 to 40 g / 10 minutes by weight of 80 to 95 parts by weight, and a pressure-sensitive adhesive having a softening point of 90 ° C. to 140 ° C. measured by the annular method (D). ) A composition containing 5 to 20 parts by weight (the total of (C) and (D) is 100 parts by weight) is more preferable.

Since the ethylene-vinyl acetate copolymer (C) is a composition excellent in maintaining initial strength and preventing fluffing, the vinyl acetate content measured by JIS K6924-1 is in the range of 3 to 18% by weight. preferable. Further, since the ethylene-vinyl acetate copolymer (C) is a composition excellent in extrusion laminating workability and prevention of fluffing of a paper container, the temperature is 190 ° C. and the load is 21. It is preferable that the melt mass flow rate measured at 18N is in the range of 5 to 40 g / 10 minutes.

As the tackifier resin (D), any one belonging to the category of tackifiers can be used, and any tackifier resin (D) may be used as long as it imparts heat-sealing properties as a tackifier. Examples of the tackifier resin (D) include petroleum resin-based, kumaron resin-based, and styrene-based adhesives that are synthetic petroleum resin-based tackifiers, and rosin-based resins and methyl ester-based resins that are natural resin-based tackifiers. , Glycerin ester-based resin, pentaeristol ester-based resin, terpene-based resin and their modified products, and the like. Among these tackifiers, synthetic petroleum resin-based tackifiers include aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymer petroleum resins. These can be used alone or in combination of two or more.

The blending ratio of the ethylene-vinyl acetate copolymer (C) and the tackifier resin (D) is 80 to 95 parts by weight of (C) and 5 to 20 parts by weight of (D) (the total of (C) and (D)). Is preferably 100 parts by weight), and in particular, (D) 10 to 15 parts by weight is more preferable because the composition is excellent in stability of heat seal strength and prevention of fluffing.

For the heat seal layer, various additives such as antioxidants, lubricants, antistatic agents, conductive agents, antiblocking agents, tackifiers and the like may be used as long as the effects of the present invention are not impaired.

The thickness of the heat seal layer is preferably 5 to 30 μm, and if it is less than 5 μm, sufficient peel strength cannot be obtained, and if it exceeds 30 μm, high cost and transparency deteriorate, which is not preferable.

The antistatic agent layer of the easily peelable film of the present invention is a cationic acrylic resin-based polymer antistatic agent (A) that satisfies the following requirements (a) to (c).
(A) Contains a methacrylic ester monomer residue unit.
(B) It has at least a quaternary ammonium salt and a methacrylic acid ester in the side chain.
(C) The weight average molecular weight is 20,000 to 100,000.

If the weight average molecular weight of the polymer-type antistatic agent (A) is less than 20,000, the peel strength will increase if it is stored in a high-temperature environment or a high-temperature and high-humidity environment after bonding, and if it exceeds 100,000. The antistatic effect is poor when the coating amount is small.

The amount of the antistatic agent applied is preferably 0.001 to 0.1 g / m ² , and if it is less than 0.001 g / ^{m 2} , the antistatic effect is low and the uniformity is poor, which is not preferable. The above is not preferable because the initial adhesiveness is poor.

The antistatic agent layer can contain a polymer type antistatic agent (A) and a small molecule type antistatic agent (B) having a weight average molecular weight of 10,000 or less. As the low molecular weight antistatic agent (B), a nonionic surfactant type, a cationic surfactant type, an anionic surfactant type, and an amphoteric ionic surfactant type are preferable, and a cationic surfactant type is preferable. More preferred. The blending ratio of the high molecular weight antistatic agent (A) and the low molecular weight antistatic agent (B) is preferably 60 to 100/40 to 0.

In the present invention, an intermediate layer may be provided between the base material layer and the heat seal layer in order to improve the adhesion between the two layers. This intermediate layer can be made of, for example, a thermoplastic resin such as a polyolefin resin, a thermoplastic elastomer, or the like. These components can be used alone or in combination of two or more. Examples of the polyolefin resin include polyethylene, ethylene copolymers (polyethylene, polypropylene, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl acrylate copolymers, etc.) and modified products thereof. Can be mentioned. Various additives such as antioxidants, lubricants, antistatic agents, conductive agents, antiblocking agents, tackifiers and the like may be used for the intermediate layer as long as the effects of the present invention are not impaired. The thickness of the intermediate layer is preferably 5 to 30 μm, more preferably 10 to 15 μm.

The easily peelable film can be produced by applying an antistatic agent to a film including a base material layer, an anchor coat layer and a heat seal layer.

The method for producing the film including the base material layer, the anchor coat layer and the heat seal layer is not particularly limited, and for example, a method of extrusion laminating the heat seal layer and a multilayer including at least one heat seal layer resin in advance. Examples thereof include a method of forming a film and laminating it with a base film. More specifically, for example, (1) an extrusion laminating method in which an anchor coating agent is applied to a base film and a heat seal layer is melt-extruded, and (2) an anchor coating agent is applied to a base film and an intermediate layer is melt-extruded. After that, an extrusion laminating method in which a heat seal layer is melt-extruded onto the base film, (3) an intermediate layer having excellent adhesion to the base material is melt-extruded onto the base film, and then the heat seal layer is melted on the base film. Extruded extrusion laminating method, (4) Coextrusion laminating method in which an anchor coating agent is applied to the base film and the intermediate layer and heat seal layer are melt-extruded at the same time, (5) Heat seal by the inflation molding method or cast molding method in advance. A method of forming a multilayer film containing at least one layer of a layer resin and attaching it to a base film coated with an anchor coating agent. (6) A multilayer film containing at least one layer of a base film coated with an anchor coating agent and a heat seal layer resin. Examples thereof include an extrusion laminating method in which a film is laminated by melt-extruding an intermediate layer using an extrusion laminating method.

Further, in order to improve the adhesiveness with the base material, known surface treatments such as corona discharge treatment, frame treatment, and plasma treatment may be applied to the adhesive surface of the base material.

The corona discharge treatment is widely used as a continuous treatment technique for the surface of a plastic film or a sheet, and is performed by passing the film through the corona atmosphere generated by the corona discharge treatment machine. The corona discharge density of 1 to 100 W / min / m ² is preferable because it has excellent adhesion to the adherend.

The frame treatment is performed by contacting the film surface with a flame generated when natural gas, propane, or the like is burned.

In plasma treatment, a simple substance or mixed gas such as argon, helium, neon, hydrogen, oxygen, and air is electronically excited by a plasma jet, and then charged particles are removed to make an electrically neutral excitation inert gas. Is performed by spraying on the surface of the film.

On the other hand, in order to enhance the adhesiveness between the anchor coating agent and the intermediate layer or the heat seal layer, ozone treatment may be applied. The ozone treatment is performed by spraying ozone on the melt film at the time of laminating the intermediate layer or the heat seal layer resin.

The apparatus for applying the antistatic agent to the antistatic agent layer of the easily peelable film of the present invention is not particularly limited. Either method such as spraying or roll coater can be used. It can be applied uniformly by any method, and it is preferable that the surface intrinsic resistance value is 1 × 10 ¹² Ω or less.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

(1) Preparation of composition for heat-sealed layer As the ethylene-vinyl acetate copolymer (C), the ethylene-vinyl acetate copolymer (C1) (manufactured by Toso Co., Ltd., trade name Ultrasen 537, containing vinyl acetate) Amount 6%, MFR 9 g / 10 minutes) 85 parts by weight, hydrogenated petroleum resin (D1) as tackifier resin (D) (trade name Alcon P125 manufactured by Arakawa Chemical Co., Ltd., softening temperature 125 ° C.) 15 parts by weight. It was pre-blended by a tumbler mixer and melt-kneaded at 180 ° C. using a twin-screw extruder (manufactured by Toshiba Machinery Co., Ltd., trade name TEM50B) rotating in the same direction to obtain pellets of the composition.

(2) Evaluation of the characteristics of the easily peelable film-Measurement of antistatic property retention-
The easily peelable film is stored in a) 23 ° C. × 50% RH constant temperature and humidity chamber, b) 60 ° C. oven, and c) 60 ° C. × 95% RH constant temperature and humidity chamber for 30 days, and the sample is taken out after 30 days. After allowing to cool for 1 hour in a 23 ° C. and 50% RH environment, the surface intrinsic resistance value of the antistatic agent layer was measured under the conditions (applied voltage 500 V, measurement time 60 seconds) in accordance with JIS K-6911.

-Measurement of antistatic maintainability (paper contact conditions)-
After stacking the antistatic agent layer of the easily peelable film and the base paper of the paper base material to be the carrier tape in a size of 10 cm × 10 cm, the sample is sandwiched between iron plates and a load of 5 kg is applied. , C) Stored in a 60 ° C. × 95% RH constant temperature and humidity chamber for 7 days each. After 7 days, the sample was taken out and only the easily peelable film was allowed to cool in a 23 ° C. 50% RH environment for 1 hour, and then antistatic under the conditions compliant with JIS K-6911 (applied voltage 500 V, measurement time 60 seconds). The surface intrinsic resistance value of the agent layer was measured.

-Measurement of maintainability of peeling characteristics (peeling strength after aging)-
The adhesive surface of the easily peelable film and the paper base material (made by Daio Paper) to be the carrier tape are overlapped, and the taping tester (manufactured by Vanguard Systems Co., Ltd., VS-120 type), U-shaped seal bar (0) Using a 5.5 mm width x 2 type, seal bar length 8.2 mm), set the heat seal time so that the average heat seal strength is about 0.25 N / mm under the conditions of 0.1 MPa and a seal pitch of 8 mm. It was adjusted and continuously pressure-heated and adhered. The sealed sample is stored in a) 23 ° C x 50% RH constant temperature and humidity chamber, b) 60 ° C oven, and c) 60 ° C x 95% RH constant temperature and humidity chamber for 30 days, and the sample is taken out after 30 days. After allowing to cool for 1 hour in a 23 ° C. and 50% RH environment, the peeling strength was continuously measured for a length of 150 mm under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min, and the average value was obtained.

As the maintainability (rate of change) of the peeling characteristics, a value obtained by dividing the peeling strength after 30 days by the initial strength immediately after heat sealing was used. The maintainability (rate of change) of the peeling characteristics was evaluated to be good in the range of 80 to 120%.

-Measurement of maintainability of peeling characteristics (peeling appearance after aging)-
The adhesive surface of the easily peelable film and the paper base material (made by Daio Paper) to be the carrier tape are overlapped, and the taping tester (manufactured by Vanguard Systems Co., Ltd., VS-120 type), U-shaped seal bar (0) Using a 5.5 mm width x 2 type, seal bar length 8.2 mm), set the heat seal time so that the average heat seal strength is about 0.25 N / mm under the conditions of 0.1 MPa and a seal pitch of 8 mm. It was adjusted and continuously pressure-heated and adhered. The sealed sample is stored in a) 23 ° C x 50% RH constant temperature and humidity chamber, b) 60 ° C oven, and c) 60 ° C x 95% RH constant temperature and humidity chamber for 30 days, and the sample is taken out after 30 days. After allowing to cool for 1 hour in a 23 ° C. and 50% RH environment, 150 mm lengths were peeled off under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min.

After peeling, the adhesive surface of the easily peelable film and the surface of the carrier tape were visually checked, and the peeled state was evaluated in two stages.

◯: There is no fluffing on the carrier tape, and no paper fibers adhere to the film surface (good).
×: The carrier tape has fluff and paper fibers adhere to the film surface (defective).
Example 1
A biaxially stretched polyester film (manufactured by Toyobo Co., Ltd., trade name E5100, 25 μm thickness) is used as the base material layer, and a urethane-based anchor coat is used as the anchor coat agent layer on the corona-treated surface of the base material. Apply 30 mg / m ² of the agent (F1) (manufactured by Takeda Yakuhin Kogyo Co., Ltd., trade names A3210, A3072, ethyl acetate, solid content concentration 7% by weight), and by adjusting the above (1) heat seal layer. The prepared composition is extruded from a T-die at a temperature of 240 ° C., and the thickness of the extruded molten film is 15 μm while being sprayed with ozone gas under the condition of 20 mg / m ² on the side to be adhered to the anchor coating agent layer. A laminated constituent film was produced by extrusion lamination processing. After that, the antistatic agent layer has a weight average molecular weight of about 70,000 as the polymer type antistatic agent (A), contains a methacrylic acid ester monomer residue unit, and has a quaternary ammonium salt in the side chain. The amount of the high molecular weight antistatic agent (A1) (manufactured by Taisei Fine Chemical Co., Ltd., trade name 1SX-1090) diluted with isopropyl alcohol to a predetermined amount and dried using a bar coater is 8 mg / It was applied on the heat-sealed layer so as to have m ² , and dried for 24 hours to obtain an easily peelable film.

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

Example 2
As an intermediate layer between the anchor coating agent layer and the heat seal layer, low-density polyethylene (E1) (manufactured by Tosoh Corporation, trade name Petrosen 203) was extruded and laminated at a temperature of 320 ° C. to a thickness of 15 μm. An easily peelable film was obtained in the same manner as in Example 1.

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

Example 3
Instead of the polymer-type antistatic agent (A1) in the antistatic agent layer, the polymer-type antistatic agent has a weight average molecular weight of about 30,000, contains a methacrylic acid ester monomer residue unit, and is sided with a quaternary ammonium salt. An easily peelable film in the same manner as in Example 2 except that a cationic acrylic polymer type antistatic agent (A2) (manufactured by Taisei Fine Chemical Co., Ltd., trade name 1SX-1055) having a chain was used. Got

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

Example 4
Instead of the polymer-type antistatic agent (A1) in the antistatic agent layer, a polymer-type antistatic agent (A1) and a cationic low-molecular-weight antistatic agent (B1) having a weight average molecular weight of 300 (Kao Co., Ltd.) ), Product name: Electrostripper QN) was mixed at a ratio of 70/30, and an antistatic agent was used so that the amount of antistatic agent applied after drying was 8 mg / m ² . Similarly, an easily peelable film was obtained.

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

Comparative Example 1
An easily peelable film was obtained in the same manner as in Example 2 except that the antistatic agent was not applied instead of the polymer type antistatic agent (A1) in the antistatic agent layer.

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

The obtained easily peelable film was inferior in antistatic property.

Comparative Example 2
Instead of the high molecular weight antistatic agent (A1) in the antistatic agent layer, a small molecule antistatic agent (B1) was used and the antistatic agent was applied so that the amount of the antistatic agent applied after drying was 8 mg / m ² . Other than that, an easily peelable film was obtained in the same manner as in Example 2.

Table 1 shows the film composition of the obtained easily peelable film, and Table 2 shows the results of evaluation by the above method.

The obtained easily peelable film was inferior in the sustainability of antistatic property and the maintainability of peeling strength in the paper contact test.

The easily peelable film of the present invention maintains the antistatic effect even when stored in a high temperature environment or a high temperature and high humidity environment, and the initial peeling strength even when stored in a high temperature environment or a high temperature and high humidity environment after bonding. It has the property of being excellent in the maintainability of the peeling property, and is useful as an easily peelable film for a lid material of a paper container, particularly as a cover tape for a paper carrier tape.

Claims (3)

The vinyl acetate content of the substrate layer, anchor coat layer, and JIS K6924-1 was in the range of 3 to 18% by weight, and the melt mass flow rate measured by JIS K6924-1 was in the range of 5 to 40 g / 10 minutes. A composition containing 80 to 95 parts by weight of a certain ethylene-vinyl acetate copolymer (C) and 5 to 20 parts by weight of a tackifier (D) having a softening point of 90 ° C. to 140 ° C. measured by a ring ball method ((C). ) And (D) are 100 parts by weight in total), and the film contains at least four layers of a heat seal layer and an antistatic agent layer in this order, and the antistatic agent layer meets the following requirements (a) to ( d ). A cover tape for a paper carrier tape made of an easily peelable film, which comprises a cationic acrylic resin-based polymer type antioxidant (A) to be satisfied.
(A) Contains a methacrylic ester monomer residue unit.
(B) Have at least a quaternary ammonium salt in the side chain.
(C) The weight average molecular weight is 30,000 to 70,000 .
(D) The coating amount is 0.001 to 0.1 g / m ² . The cover tape for a paper carrier tape according to claim 1, wherein the antistatic agent further contains a low molecular weight antistatic agent (B) having a weight average molecular weight of 10,000 or less. The cover tape for a paper carrier tape according to claim 1 or 2 , further comprising an intermediate layer made of a polyethylene resin between the anchor coat layer and the heat seal layer.