JP4932244B2 - Heat seal film - Google Patents

Description

The present invention relates to a heat seal film used for a packaging container.

Heat seal films for sealing containers such as plastic and paper are used in various fields such as packaging of electronic parts typified by carrier tape. When using a heat seal film as a cover tape for a carrier tape, the important performance required for a heat seal film as a lid material is that it cannot be easily peeled off during transportation and storage, and it is easily peeled off when the contents are taken out during mounting. And the cover tape cannot be cut.
The cover tape is usually used by slitting a film raw material having a width of several hundred millimeters or more into a width as required by a slitter. At this time, if the peel strength varies in the width direction of the raw material For example, when adjusting the sealing conditions using the slit product with the lowest peel strength, the peel strength becomes too high if the slit product with the highest peel strength is sealed under the same conditions. In some cases, the cover tape is cut and the contents cannot be taken out. In the opposite case, since the peel strength is too low, the cover tape may be peeled off during storage or transportation, and the contents may spill out of the container. It is desired that the peel strength of the raw film for the cover tape is stable regardless of the position at which it is used. Patent Documents 1 to 3 describe easy-openability and transparency when a heat seal film is used as a cover tape, but do not describe stabilization of the peel strength.
Special table 2003-508253 gazette JP 2002-179183 A JP 2004-244115 A

The present invention provides a heat seal film with small variations in peel strength.

The present invention solves the above problems by the following means.
(1) (a) The number average molecular weight Mn is 140 to 180,000 g / mol, and the number average molecular weight of the styrenic hydrocarbon block is 10,000 g / mol or more and less than 50,000 g / mol, 5 to 50% by mass of a block copolymer of 50 to 95% by mass of a styrenic hydrocarbon and 5 to 50% by mass of a conjugated diene hydrocarbon,
(B) 5 to 50% by mass of an ethylene-α olefin copolymer,
(C) 5 to 70% by mass of a block copolymer of 10 to 50% by mass of styrene hydrocarbon and 90 to 50% by mass of conjugated diene hydrocarbon
A heat seal film comprising a resin composition comprising: a sealant layer.
(2) (a) The number average molecular weight Mn is 140 to 180,000 g / mol, and the number average molecular weight of the styrenic hydrocarbon block is 10,000 g / mol or more and less than 50,000 g / mol, 5 to 50% by mass of a block copolymer of 50 to 95% by mass of a styrenic hydrocarbon and 5 to 50% by mass of a conjugated diene hydrocarbon,
(B) 5 to 50% by mass of an ethylene-α olefin copolymer,
(C) 5 to 70% by mass of a block copolymer of 10 to 50% by mass of styrene hydrocarbon and 90 to 50% by mass of conjugated diene hydrocarbon
The manufacturing method of the heat seal film which used the resin composition which consists of as a sealant layer.
(3) A heat seal film comprising 50 to 99% by mass of the resin composition (a) to (c) of (1) and 1 to 50% by mass of impact-resistant polystyrene as a sealant layer.
(4) A method for producing a heat seal film using 50 to 99% by mass of the resin composition (a) to (c) of (1) and 1 to 50% by mass of impact-resistant polystyrene as a sealant layer.
(5) The layer structure is at least 4 layers, and is outermost layer / biaxially stretched polyethylene terephthalate layer, second layer / polyethylene resin layer, third layer / polyolefin resin layer, fourth layer / sealant layer The heat seal film according to the above (1) or (3).
(6) The manufacturing method of the heat seal film as described in said (5).
(7) The method for producing a heat seal film according to (5), wherein the third polyolefin resin layer and the fourth sealant layer are produced by a co-extrusion method.
(8) The heat seal film according to any one of the above (1), (3), and (5), wherein an antistatic treatment is performed on at least one side.
(9) A cover tape for a semiconductor / electronic component carrier tape comprising the heat seal film according to any one of (1), (3), (5), and (8).
(10) A semiconductor / electronic component container using the heat seal film according to any one of (1), (3), (5), and (8).

ADVANTAGE OF THE INVENTION According to this invention, the heat seal film with small variation in peeling strength can be provided.

Hereinafter, the present invention will be described in detail.
Examples of the styrenic hydrocarbon used in the present invention include styrene, α-methylstyrene, and various alkyl-substituted styrenes. Of these, styrene can be preferably used. Examples of the conjugated diene hydrocarbon include isoprene and butadiene. Of these, butadiene can be preferably used. The block copolymer includes those in which hydrogen is added to an unsaturated bond part derived from a conjugated diene hydrocarbon of a block copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon. Among these block copolymers, one type can be used as each of (a) and (c), but two or more types can be used in combination.

  Examples of the α-olefin in the ethylene-α-olefin copolymer include propylene, butene, pentene, hexene and the like. A random copolymer having a structure in which an ethylene component and an α-olefin component are randomly arranged is preferable.

  As impact-resistant polystyrene, those in which soft component particles made of a conjugated diene hydrocarbon polymer are dispersed in a matrix of a styrene hydrocarbon polymer can be suitably used.

The block copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon in (a) has a number average molecular weight of 140 to 180,000 g / mol of the chloroform-soluble component, and the number of styrene-based hydrocarbon block components. The average molecular weight is 10,000 g / mol or more and less than 50,000 g / mol. Preferably, the former is 140 to 160,000 g / mol, and the latter is 2 to 40,000 g / mol.

A commercially available thing can be used as an ethylene-alpha olefin copolymer and an impact-resistant polystyrene.

  The compounding of the resin composition of (a)-(c) is (a) 5-50 mass%, (b) 5-50 mass%, (c) 5-70 mass%. Preferably, (a) 30 to 45% by mass, (b) 20 to 40% by mass, and (c) 10 to 25% by mass. Moreover, the compounding of the resin composition (a) to (c) and the resin (d) is 50 to 99 mass% of the resin composition (a) to (c) and 1 to 50 mass% of (d). Preferably, the former is 70 to 90% by mass and the latter is 10 to 30% by mass. If (a) is less than 5% by mass, it may be difficult to form a film. If it exceeds 50% by mass, the temperature dependency of the peel strength tends to be remarkable, and the easy-openability tends to be impaired. If (b) is less than 5% by mass, sufficient peel strength may not be obtained, and if it exceeds 50% by mass, the adhesiveness to the roll during film formation may be large and it may be difficult to form a film. When (c) is less than 5% by mass, it becomes difficult to obtain the sealing conditions necessary for imparting easy-openability, and when it exceeds 70% by mass, it may be difficult to form a film. In (d), when it exceeds 50 mass%, the transparency of the film tends to decrease.

  The heat seal film has a layer structure of at least 4 layers, and a biaxially stretched polyethylene terephthalate layer is an outermost layer, a polyethylene resin layer as a second layer in contact therewith, a polyolefin resin layer as a third layer in contact with the second layer, a third layer The fourth layer in contact with can be suitably used in the configuration of the sealant layer described above.

  The biaxially stretched polyethylene terephthalate used for the biaxially stretched polyethylene terephthalate layer is not only those that are usually used, but also those that have been coated or kneaded with antistatic agents, those that have been subjected to antistatic treatment and corona treatment, etc. Can be used.

For the polyethylene resin layer, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, or the like can be used, and these can be used alone or in combination. Also, ethylene-1-butene, a copolymer of ethylene and a vinyl group having a carboxylic acid group, such as an ethylene-acrylic acid ester, an ethylene-vinyl acetate copolymer, and a terpolymer with an acid anhydride It can be blended and used. Among these, low density polyethylene and linear low density polyethylene can be preferably used.

  Various anchor coating agents and surface treatment techniques that are generally used for further strengthening the adhesion between the outermost layer and the second layer can be used. As the anchor coating agent, a two-component curable isocyanate-based anchor coating agent can be used particularly for strengthening the adhesion between the biaxially stretched polyethylene terephthalate and the polyethylene resin. Further, in order to further strengthen the adhesion between the anchor coating agent and the biaxially stretched polyethylene terephthalate film, corona treatment can be performed on the biaxially stretched polyethylene terephthalate film side and ozone treatment can be performed on the polyethylene resin side.

Examples of the polyolefin resin used in the polyolefin resin layer include ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-maleic acid copolymer, and styrene-ethylene. Examples thereof include graft copolymers, styrene-propylene graft copolymers, styrene-ethylene-butadiene block copolymers, propylene polymers, ethylene polymers, and blends thereof.
Among these, a blend of an ethylene-1-butene copolymer and an ethylene polymer can be suitably used.

  As a method for producing the laminated film of the present invention, general techniques such as an extrusion coating method and an extrusion lamination method can be used, and among these, the extrusion lamination method is preferable. The third polyolefin resin layer and the fourth sealant layer can be obtained as a two-layer film by co-extrusion, and a method of obtaining a two-layer film by the T-die method is particularly preferable. In addition, the obtained two-layer film can be laminated with a biaxially stretched polyethylene terephthalate layer through a polyethylene resin layer that is a melted second layer to form a heat seal film.

  The heat seal film obtained in the present invention can be subjected to antistatic treatment on at least one side of the base material surface and the sealant film surface. In the antistatic treatment, as the antistatic agent, a surfactant type antistatic agent, a polymer type antistatic agent, a conductive agent or the like can be applied by a roll coater or a spray using a gravure roll or the like.

  The heat seal film obtained in the present invention can be used for a cover tape for an electronic component carrier tape or an electronic component transport container used for storage, transportation and mounting of electronic components.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these.
(Examples 3 to 5 and Experimental Examples 1 and 2 )
As a resin composition of the sealant layer, 42.5 parts by mass of (a) 1 to (a) 5 styrene-butadiene block copolymer resin (styrene content 80% by mass, butadiene content 20% by mass) shown in Table 1, (B) 25 parts by mass of an ethylene-butene-1 random copolymer (trade name Toughmer A-4085, manufactured by Mitsui Chemicals) and (c) a styrene-butadiene block copolymer (styrene content 40% by mass, butadiene content 60) 40% Extruder To obtain a resin composition. A two-layer film (total thickness 33 μm) was obtained by co-extrusion of low-density polyethylene as the resin composition and polyolefin resin using a T-die method. This two-layer film was laminated with a biaxially stretched polyethylene terephthalate film (thickness: 16 μm) via a polyethylene resin (thickness: 13 μm) by an extrusion laminating method to obtain heat seal films each having an width of 880 mm.

Gel permeation chromatography (GPC) was used as a method for measuring the molecular weight of the block copolymer (a) of styrene hydrocarbon and conjugated diene hydrocarbon. The measurement conditions are shown below.
Measurement conditions Solvent (mobile phase): THF
Flow rate: 0.2 ml / min
Set temperature: 40 ° C
Column configuration: Showa Denko KF-G 4.6 mm ID × 10 cm 1 and Showa Denko KF-404HQ 4.6 mm ID × 25 cm (theoretical plate number 25,000 plates), 5 in total (100,000 theoretical plate samples as a whole Sample injection Amount: 10 μl (sample solution concentration 3 mg / ml)
Liquid feeding pressure: 127 kg / cm ²
Detector: RI detector The method for measuring the molecular weight of a styrene hydrocarbon present as a block homopolymer segment in the block copolymer (a) of a styrene hydrocarbon and a conjugated diene hydrocarbon is as follows. went.
0.1 g of a sample of block copolymer (a) of styrene hydrocarbon and conjugated diene hydrocarbon is taken and dissolved in 20 cc of chloroform, and then added with 70% aqueous solution of t-BuOOH, 1% chloroform solution of OsO ₄ and distilled water. , Reacted at 90 ° C. for 30 minutes (decomposition reaction). After cooling this solution, it was poured into methanol to obtain a block homopolymer of styrenic hydrocarbon. The molecular weight of this polymer was measured in the same manner as the molecular weight of the block copolymer (a) of styrene hydrocarbon and conjugated diene hydrocarbon.

(Example 6 , Experimental Examples 3-7 )
The same operation as in Example 3 was performed except that the resin composition of the sealant layer was obtained by blending the resin (a) and the resin shown in Table 2.

Except that (a) 6 to (a) 8 styrene-butadiene block copolymer resins (styrene content 80% by mass, butadiene content 20% by mass) shown in Table 1 were used for the resin composition of the sealant layer, Examples The same operation as 3 was performed.

The following evaluations were performed on the films obtained in Examples , Experimental Examples, and Comparative Examples.
(1) Peel strength variation evaluation Twenty test pieces (width 21 mm, length 20 cm) were cut out at equal intervals in the width direction from the obtained film, the seal head width 0.5 mm × 2, the seal pressure 0.34 MPa, and the seal time The peel strength was measured after sealing the heat-sealed film to a polystyrene carrier tape (24 mm width) for electronic packaging material at 155 ° C. under conditions of 0.5 seconds and the number of times of sealing twice. The peel strength is generally controlled at 30 gf at the lowest, and if it is lower than 10 gf, the peel strength is high. The range shown in Table 2 is a value obtained by subtracting the minimum value from the maximum value of the peel strength. A range of 10 gf or less was determined to be excellent, a range of 20 gf or less was determined to be good, and a range higher than that was determined to be poor.

According to the present invention, since the peel strength variation in the width direction of the original film is reduced, the peel strength of the cover tape obtained therefrom is stable, and the cover tape breaks during mounting due to the peel strength becoming too high. It is possible to obtain a heat seal film free from troubles and troubles caused by peeling of the cover tape during storage or transportation due to excessively low peel strength.

Claims (7)

(A) a number average molecular weight Mn of 14 to 160,000 g / mol, and wherein the number average molecular weight of styrene series hydrocarbon block is from 2 to 40,000 g / mol, a styrene series hydrocarbon 50 A block copolymer of 5 to 50% by mass of 95% by mass and a conjugated diene hydrocarbon of 5 to 50% by mass;
(B) 5 to 50% by mass of an ethylene-α olefin copolymer,
(C) 5 to 70% by mass of a block copolymer of 10 to 50% by mass of styrene hydrocarbon and 90 to 50% by mass of conjugated diene hydrocarbon
A heat seal film for a semiconductor / electronic component carrier tape comprising 70 to 90% by mass of a resin composition and 10 to 30% by mass of impact-resistant polystyrene as a sealant layer. (A) a number average molecular weight Mn of 14 to 160,000 g / mol, and wherein the number average molecular weight of styrene series hydrocarbon block is from 2 to 40,000 g / mol, a styrene series hydrocarbon 50 A block copolymer of 5 to 50% by mass of 95% by mass and a conjugated diene hydrocarbon of 5 to 50% by mass;
(B) 5 to 50% by mass of an ethylene-α olefin copolymer,
(C) 5 to 70% by mass of a block copolymer of 10 to 50% by mass of styrene hydrocarbon and 90 to 50% by mass of conjugated diene hydrocarbon
The manufacturing method of the heat seal film for semiconductor and electronic component carrier tapes using the resin composition 70-90 mass% which consists of, and 10-30 mass% of impact-resistant polystyrene as a sealant layer. Outermost layer / biaxially oriented polyethylene terephthalate layer having a layer structure of at least four layers, the second layer / polyethylene resin layer, third layer / polyolefin resin layer, claim, characterized in that a fourth layer / sealant layer 1 heat-sealing film of the serial mounting. The manufacturing method of the heat seal film of Claim 3 . 4. The heat seal film according to claim 3 , wherein the third polyolefin resin layer and the fourth sealant layer are produced by a co-extrusion method. 4. The heat seal film according to claim 1, wherein an antistatic treatment is performed on at least one side. Claim 1,3, semiconductors and electronic components container using a heat-sealing film according to one of 6.