JP4708048B2 - Styrenic resin sheet and embossed carrier tape - Google Patents

Description

  The present invention relates to a sheet made of a styrenic resin composition and an embossed carrier tape.

In general, styrenic resins are excellent in molding processability, rigidity, transparency and the like, are inexpensive, have low specific gravity, and are economically superior. Sheets made of styrenic resins are used in various fields. In particular, it is also used as packaging and transport containers for electronic parts such as embossed carrier tapes. In this case, the required characteristics of the sheet are transparency, impact resistance, heat resistance, rigidity, folding resistance (foldability), embossing It is desired that there is formability at the time of molding or punching, and that the balance of each characteristic is suitable.
Various embossed carrier tape sheets made of styrene resins have been proposed. For example, Patent Document 1 proposes to add a styrene-diene elastomer for the purpose of improving the folding strength of the sheet. Patent Document 2 discloses the use of a styrene-conjugated diene block copolymer in order to improve the transparency and rigidity of the sheet.
Japanese Patent Laid-Open No. 10-236576 JP 2002-331621 A

However, in the technique described in Patent Document 1, although the bending strength is improved, the rigidity of the embossed molded product is not sufficient because the rigidity is lowered. Further, the technique described in Patent Document 2 does not improve the bending strength. Thus, the sheet | seat which consists of styrene resin which fully satisfy | fills each characteristic as an object for embossed carrier tapes is not obtained.
In addition, in conventional styrene resin sheets and embossed carrier tapes, changes in physical properties over time are not taken into consideration.For example, until the size and appearance do not change due to high temperature conditions during transportation and storage in summer. However, there is a problem that the bending strength is extremely lowered. Thus, when the bending strength is lowered, cracking is likely to occur, and when it is bent unexpectedly in the embossing process or the parts loading / unloading process, there arises a problem that cracks and cracks are generated and workability is significantly reduced.
As a method for forming the embossed carrier tape, there are pressure forming, vacuum forming, press forming and the like, and the sheet is heated and softened to form a predetermined pocket (emboss) with a mold. In the conventional styrene resin sheet, due to excessive drawdown of the heated part, uneven pockets and holes in the pocket part, and mold deformation of the flange part occur, and the drive ( There has also been a problem that troubles such as (feed) defects and defective parts loading and unloading occur.

  The present invention has been made in order to solve the above problems, and has a transparency, impact resistance, heat resistance, rigidity, bending strength, and a styrenic resin sheet having good moldability at the time of embossing and punching, and An object is to provide an embossed carrier tape.

The sheet of the present invention comprises a styrene-conjugated diene block copolymer (A), a styrene-conjugated diene block copolymer (B) other than the styrene-conjugated diene block copolymer (A), a polystyrene resin (C), And impact resistant polystyrene resin (D),
The styrene-conjugated diene block copolymer (A) has a styrene monomer content of 65 to 85% by mass, and the conjugated diene block contains 75% by mass or more and 100% by mass of a conjugated diene homopolymer or conjugated diene. It is a copolymer composed of a conjugated diene and a styrenic monomer containing less than
The styrene-conjugated diene block copolymer (B) has a styrene monomer content of 65 to 85% by mass, and the conjugated diene block contains conjugated diene in an amount of 50% by mass to less than 75% by mass. And a styrene monomer copolymer,
The peak molecular weight of the styrene block of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) is in the range of 30,000 to 80,000, and the molecular weight distribution curve of the styrene block is half of The price range is 1.3 to 3.0,
The mass ratio (A / B) of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) is in the range of 95/5 to 25/75,
The content of the polystyrene resin (C) is 20 to 110 parts by mass with respect to a total of 100 parts by mass of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B),
The content of the impact-resistant polystyrene resin (D) is 5 to 35 parts by mass with respect to a total of 100 parts by mass of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B). It consists of a certain styrenic resin composition.
The embossed carrier tape of the present invention is formed by molding the above sheet.

  According to the present invention, the heat resistance, impact resistance, transparency, and rigidity are excellent, and even if the storage temperature rises during storage or transportation, the bending strength does not easily decrease and is good. A sheet having a good moldability and an embossed carrier tape can be obtained.

The styrene resin composition according to the present invention comprises a styrene-conjugated diene block copolymer (A), a styrene-conjugated diene block copolymer (B) other than the styrene-conjugated diene block copolymer (A), polystyrene. Resin (C) and impact-resistant polystyrene resin (D) are contained.
The styrene-conjugated diene block copolymer of component (A) and component (B) has at least one styrene polymer block (styrene block) mainly composed of a styrene monomer in the block copolymer. A block copolymer having at least one conjugated diene polymer block mainly composed of a conjugated diene monomer.
Examples of the styrenic monomer include styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl styrene, 1,3-dimethyl styrene, α-methyl styrene, vinyl naphthalene, and vinyl anthracene. Styrene is mentioned as a general thing. These may be used alone or in combination of two or more.
The conjugated diene monomer is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1, There are 3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc., and particularly common ones include 1,3-butadiene and isoprene.
In both the component (A) and the component (B), the content of the styrene monomer in the styrene-conjugated diene block copolymer is 65 to 85% by mass, preferably 70 to 80% by mass. If it is less than 65% by mass, the rigidity and heat resistance are poor, and if it exceeds 85% by mass, the impact resistance tends to be inferior.

In both the component (A) and the component (B), the peak molecular weight of the styrene block is 30,000 to 80,000, preferably 32,000 to 75,000, and more preferably 35,000 to 70,000.
When the peak molecular weight of the styrene block is in the above range, the embossing moldability is excellent.
The peak molecular weight of the styrene block in the styrene-conjugated diene block copolymer is determined by a method in which styrene-conjugated diene block copolymer is oxidatively decomposed with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IMKOLTHOFF, etal. , J. Polym. Sci. 1,429 (1946) (hereinafter also referred to as the osmium tetroxide method), the molecular weight is specified by gel permeation chromatography (GPC). . The molecular weight is measured by GPC measurement of monodisperse polystyrene for GPC, and a calibration curve is created between the peak count number and the number average molecular weight of monodisperse polystyrene. (For example, “Gel Chromatography <Basics>” published by Kodansha) Calculate according to

In both the component (A) and the component (B), the FWHM of the molecular weight distribution curve of the styrene block is 1.3 to 3.0, preferably 1.5 to 2.8, and more preferably 1.7 to 2.6. When the half width of the molecular weight distribution curve of the styrene block is within the above range, the embossing formability is excellent.
In addition, the half value width of the molecular weight distribution curve of a styrene block can be calculated | required from the molecular weight distribution chart which calculated | required the peak molecular weight of the styrene block mentioned above. Specifically, the molecular weight is expressed in logarithm, the range of 1000 to 1000000 on the horizontal axis is 15 cm, the concentration (mass ratio) is displayed on the vertical axis at an arbitrary height, and the peak at 50% of the peak top height is displayed. The width (cm) on the horizontal axis is the half-value width. In this case, the peak top height is perpendicular to the horizontal axis, and the peak width at 50% of the height needs to be horizontal to the horizontal axis.

In both the component (A) and the component (B), examples of the structure of the styrene-conjugated diene block copolymer include a linear shape, a star shape, and a taper shape. Of these, a linear shape and a star shape are preferable. used.
In both the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B), the MFR value is preferably 2 to 35 g / 10 minutes, and more preferably 3 to 25 g / 10 minutes.
The value of MFR (melt flow rate) is a value obtained by measurement under the conditions of 200 ° C. and a load of 5 kgf by the method specified in JIS K7210 (Method A).

Both the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) preferably have a glass transition temperature of 83 ° C. or higher, more preferably 85 ° C. or higher. When the glass transition temperature is less than 83 ° C., the heat resistance of the sheet or embossed carrier tape is greatly reduced.
The value of the glass transition temperature is a value obtained by DSC measurement (differential scanning calorimetry) under conditions of a temperature rising temperature of 10 ° C./min and a temperature range of 20 to 200 ° C.

The flexural modulus of the styrene-conjugated diene block copolymer (A) is preferably in the range of 1300 to 1900 MPa, more preferably in the range of 1400 to 1800 MPa. When the flexural modulus of the styrene-conjugated diene block copolymer (A) is in the above range, the sheet has excellent rigidity, the pocket portion of the embossed carrier tape is not easily crushed, and the pocket formed in a relatively deep-drawn shape is also high. Strength can be obtained. If the flexural modulus is less than 1300 MPa, the strength of the embossed molded product is impaired, so it is not suitable for use. If the flexural modulus exceeds 1900 MPa, the impact resistance and folding strength of the sheet decrease.
The value of the flexural modulus is a value obtained according to JIS K7171.

The conjugated diene block in the styrene-conjugated diene block copolymer (A) is a copolymer consisting of a conjugated diene homopolymer or a conjugated diene containing 75% by mass to less than 100% by mass of a conjugated diene and a styrene monomer. It is a coalescence. The form of the styrene-conjugated diene block copolymer (A) is a so-called microphase separation in which the conjugated diene polymer (conjugated diene block) has a size of 0.1 μm or less and is finely dispersed in the sea phase made of styrene polymer. Forming a structure.
In the styrene-conjugated diene block copolymer (A) having such a microphase-separated structure, immediately after melt-kneading with an extruder or Banbury mixer and cooling the discharged product, the styrene polymer and conjugated diene are used. There are many phases (interface phases) in which polymers are mixed. A molded product such as a sheet in a phase state and a carrier tape in which many interfacial phases exist is difficult to break even when bent and is ductile. However, since the styrene polymer and the conjugated diene polymer are incompatible with each other, the interfacial phase decreases with time, and shows a remarkable decrease particularly in a high temperature environment (temperature above normal temperature and below glass transition temperature). When the interfacial phase is reduced, the folding strength of the sheet is lowered, and a molded product such as a carrier tape is easily broken when it is bent.
Such a decrease in the interfacial phase can be confirmed, for example, by measuring the dynamic viscoelasticity of the sheet. Specifically, the sheet of styrene-conjugated diene block copolymer (A) was stored at room temperature (23 ° C.) and stored at 60 ° C. for 72 hours for dynamic viscoelasticity. Measure temperature dependence.
The temperature dependence of the dynamic viscoelasticity of the sheet is measured in accordance with the temperature dependence measurement method stipulated in JIS K7244-4-1999, in a temperature range of 20 to 200 ° C., a frequency of 1 Hz, and a heating rate of 5 Perform under conditions of ° C / min. Then, the peak value of the loss coefficient tanδ in the main dispersion temperature region is read from the obtained dynamic viscoelastic temperature dependence curve. The main dispersion temperature region here is the glass transition temperature region, and when the polymer chain starts micro-Brownian motion, the storage elastic modulus E ′ is remarkably reduced, indicating a bending point called dispersion, and temperature-loss The elastic modulus E ”curve and the temperature-loss coefficient tan δ curve show a maximum called α-peak.
Comparing the loss elastic modulus E "and loss factor tanδ near 50 to 90 ° C in the obtained dynamic viscoelastic temperature dependence curve, the value of the one stored at a lower temperature than the one stored at a normal temperature decreases. This suggests that the mixed portion of the styrene polymer and the conjugated diene polymer is reduced and phase-separated in a high temperature environment.

In the present invention, the combined use of the styrene-conjugated diene block copolymer (B) having a polymer structure different from that of the styrene-conjugated diene block copolymer (A) facilitates cracking of the heat-stored sheet or carrier tape. Is improved.
The styrene-conjugated diene block copolymer (B) is a copolymer comprising a conjugated diene and a styrene monomer in which the conjugated diene block in the block copolymer contains 50% by mass or more and less than 75% by mass of the conjugated diene. It is a coalescence. The copolymer of the conjugated diene block is preferably a random copolymer. In the styrene-conjugated diene block copolymer (B), the fine dispersed phase composed of the conjugated diene block is in a state in which the styrene monomer component and the conjugated diene monomer component are premixed by copolymerization, This dispersed phase itself corresponds to the interfacial phase referred to in the styrene-conjugated diene block copolymer (A). Since the dispersed phase of the styrene-conjugated diene block copolymer (B) is made of a copolymer, it maintains ductile behavior and does not generate cracks or cracks even when exposed to a high temperature environment in a sheet or carrier tape. Has the advantage.
The flexural modulus of the styrene-conjugated diene block copolymer (B) is preferably 900-1500 Mpa, more preferably 1000-1400 Mpa. If it is less than 900 MPa, the rigidity of the sheet is remarkably lowered, and if it exceeds 1500 MPa, it is difficult to obtain the effect of suppressing cracking after heating and storage.
The mass ratio (expressed as A / B) of the content of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) is 95/5 to 25/75, preferably 90/10 It is preferably in the range of -30/70. If the mass ratio of the styrene-conjugated diene block copolymer (B) is less than the above range, the bending strength after heat storage is not sufficiently improved, and the mass ratio of the styrene-conjugated diene block copolymer (B) is the above If it exceeds the range, the heat resistance and the rigidity of the sheet are lowered, and the strength of the embossed pocket portion is easily impaired.

Polystyrene resin (C) includes styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl styrene, 1,3-dimethyl styrene, α-methyl styrene, vinyl naphthalene, vinyl anthracene, and other aromatic vinyl monomers. A polymer mainly composed of a monomer can be used. Of these, styrene is preferably used.
The MFR of the polystyrene resin (C) is 0.3 to 35 g / 10 minutes, preferably 0.8 to 25 g / 10 minutes, and the flexural modulus is 2500 to 3800 MPa, preferably 2800 to 3500 MPa.
A commercially available polystyrene resin (C) can be used.
The content of the polystyrene resin (C) is 20 to 110 parts by mass with respect to a total of 100 parts by mass of the block copolymer of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B). The amount is preferably 30 to 100 parts by mass. When the polystyrene resin (C) is less than the above range, the heat resistance is lowered, and the strength of the pocket portion is impaired due to a reduction in sheet rigidity. When the amount of the polystyrene resin (C) is more than the above range, the bending strength and impact resistance are lowered. Further, in the measurement of the temperature dependence of the dynamic viscoelasticity of the sheet, the peak value of the loss coefficient in the main dispersion temperature region does not satisfy a desired value, and the embossing formability is impaired.

The impact-resistant polystyrene resin (D) used in the present invention is a resin in which a rubber polymer is dispersed as islands in the form of salami particles in a sea phase made of an aromatic vinyl polymer. A graft copolymer of a polymer and a rubber polymer.
The impact resistant polystyrene resin (D) has an MFR of 0.5 to 35 g / 10 min, preferably 1.0 to 25 g / 10 min, and a flexural modulus of 1300 to 2800 MPa, preferably 1500 to 2600 MPa.
Commercially available impact-resistant polystyrene resin (D) can be used.
The content of the impact-resistant polystyrene resin (D) is preferably 5 to 35 parts by mass with respect to 100 parts by mass in total of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B). Is 10-30 parts by mass. If the impact resistant polystyrene resin (D) is less than the above range, the impact resistance is lowered. If the amount of impact-resistant polystyrene resin (D) is greater than the above range, the transparency will be lowered, and burrs will be generated in the punched holes (positioning holes for positioning) of the embossed carrier tape. Furthermore, there is a possibility that burrs may be mixed into electronic parts.

The sheet of the present invention is a styrene containing the styrene-conjugated diene block copolymer (A), styrene-conjugated diene block copolymer (B), polystyrene resin (C), and high-impact polystyrene resin (D). It is obtained by molding a resin composition into a sheet.
Depending on the intended use of the sheet, the styrenic resin composition may be added to an antistatic agent, a conductive filler such as carbon black, an ionic conductive polymer, an organic conductive polymer, a weathering agent, a light resistance agent, an antioxidant, a release agent. Molding agents, antiblocking agents, pigments, flame retardants, and the like can be added and mixed, and can also be applied to the sheet surface.
Although the method for forming the sheet is not particularly limited, for example, calendar forming, single-layer T-die extrusion molding, a manufacturing method using a feed block or a multi-manifold die, or the like can be used.
Sheet edge materials (edges, defective products, etc.) generated during sheet production can be added to the styrene resin composition and reused.
The layer structure of the sheet is not particularly limited, and may be a single layer or two or more layers.
The thickness of the styrene resin sheet of the present invention is not particularly limited, but when used as an embossed carrier tape sheet, a range of 0.1 mm to 1.0 mm is preferable, and a range of 0.2 mm to 0.5 mm is more preferable.
In general, the greater the thickness of the resin sheet, the greater the amount of deformation at the outer periphery of the fold, so the folding strength tends to deteriorate. Conventional embossed carrier tape sheets that are inferior in stretching cannot follow deformation when bent as the sheet is thicker, and cracks are likely to occur in the outer periphery of the bent. In particular, when the thickness exceeds 0.3 mm, the bending strength tends to decrease significantly, and the embossed carrier tape is likely to be bent and broken.
On the other hand, the styrenic resin sheet of the present invention has improved folding strength at any sheet thickness, and has excellent folding strength.
Specifically, the sheet of the present invention can achieve a folding strength value in the longitudinal direction of the sheet during storage at room temperature of 30 times or more, preferably 80 times or more. If the folding strength is less than 30 times, it tends to break when it is used as an embossed carrier tape.
In addition, the sheet of the present invention can achieve a folding strength in the longitudinal direction of the sheet of 30 times or more, preferably 80 times or more after being heated and stored at 60 ° C. for 72 hours. Therefore, specific destabilization due to storage conditions such as summer storage and transportation of sheets and embossed carrier tapes can be suppressed.
In addition, the value of the folding strength of the sheet is a value (unit: times) of the folding resistance measured in accordance with JIS P8115-2001 under the conditions of a load of 1.0 kgf and a bending angle of 135 °.

In the sheet of the present invention, the peak value of the loss coefficient tanδ in the main dispersion temperature region in the temperature dependence measurement result of dynamic viscoelasticity can be 3.0 or less.
Usually, when embossing a sheet, the sheet is heated above the glass transition temperature. If the peak value of the loss coefficient in the main dispersion temperature range of the sheet exceeds 3.0, the heated part will draw down too much, causing uneven pockets and holes in the pocket, and the flange part will lose shape due to expansion and contraction. As a result, the predetermined embossed shape and dimensions are not satisfied. In order to effectively exhibit good embossing, the peak value of the loss factor is preferably 1.8 to 3.0.
The tensile elastic modulus of the sheet of the present invention can be 1500 MPa or more, preferably 1800 MPa or more. The tensile yield point strength is preferably 20 MPa or more, more preferably 30 MPa or more. If the tensile modulus is less than 1500 MPa or the yield point strength is less than 20 MPa, the embossed carrier tape has insufficient pocket strength and is easily crushed.
The tensile impact strength of the embossed carrier tape sheet of the present invention is preferably 50 KJ / m ² or more, more preferably 70 KJ / m ² or more. If it is less than 50 KJ / m ² , breakage is likely to occur when a sudden tension is applied during the feed drive in the embossed carrier tape manufacturing process, parts loading and unloading processes, and this is disadvantageous in terms of work.
The softening temperature of the embossed carrier tape sheet of the present invention is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. When the temperature is lower than 60 ° C., the sheet and the embossed carrier tape are easily deformed when the temperature rises during storage and transportation.
The haze value of the embossed carrier tape sheet of the present invention is preferably 30% or less, more preferably 25% or less. The embossed carrier tape sheet of the present invention preferably has a total light transmittance of 88% or more. When the haze exceeds 30% and the total light transmittance is less than 88%, it is difficult to visually inspect and confirm the parts loaded on the embossed carrier tape with a camera or the like.
In addition, each value of said tensile elasticity modulus, tensile yield point strength, tensile impact strength, softening temperature, haze, and total light transmittance is a value obtained by the measuring method in the below-mentioned Example.
The embossed carrier tape of the present invention is obtained by molding the embossed carrier tape sheet of the present invention into a shape having a pocket portion having a desired shape.
The method for producing the embossed carrier tape is not particularly limited, and for example, vacuum forming, pressure forming, press forming, rotary forming (high speed, low speed) and the like can be used.
In addition, a silicone oil or a solution obtained by adding an emulsifier or surfactant to silicone oil to form an aqueous solution on at least one surface of an embossed carrier tape sheet is applied with a gravure roll coater method or a spray method, and then dried with hot air May be used. Such a sheet having a silicone oil-containing surface layer has good releasability from the mold of the embossing machine, so that the embossing formability is improved, and is an embossed carrier tape and its cover material. The sealing property with the cover tape is stable.

Examples are shown below, but the present invention is not limited by these.
(Examples 1-7 and Comparative Examples 1-7)
The resin compositions having the compositions shown in Tables 1 and 2 below were melt-kneaded with an extruder, discharged from a T-die, and then roll-cooled to obtain a sheet having a width of 640 mm and a thickness of 0.4 mm. The details of the resin used are as follows.
-Styrene-conjugated diene block copolymer resin (A): styrene content 77 wt%, conjugated diene block 95% conjugated diene content, styrene block peak molecular weight 36,000, half width of styrene block molecular weight distribution curve 1.9, MFR 10 g / 10 min, glass transition temperature 89 ° C, flexural modulus 1600 MPa
-Styrene-conjugated diene block copolymer resin (B): styrene content 75 wt%, conjugated diene block 65 mass%, styrene block peak molecular weights 37,000 and 54,000, styrene block molecular weight distribution curve Half width 2.5, MFR6g / 10min, glass transition temperature 87 ℃, flexural modulus 1200MPa
・ Polystyrene resin (C): SGP10 (manufactured by PS Japan, MFR1.9g / 10min, flexural modulus 3300MPa)
-Impact resistant polystyrene resin (D): HT478 (manufactured by PS Japan, MFR 3.3 g / 10 min, flexural modulus of 3300 MPa)
Styrene-conjugated diene block copolymer resin (E): styrene content 75 wt%, conjugated diene block conjugated diene content 65% by mass, styrene block peak molecular weights 10,000 and 85,000, styrene block molecular weight distribution curve FWHM 1.2 and 3.1, MFR5g / 10min, glass transition temperature 88 ℃, flexural modulus 1500MPa

The characteristics of the manufactured sheet were evaluated as follows. The evaluation results are shown in Tables 3 and 4.
[Folding resistance of sheet]
Folding strength was measured in the longitudinal direction of a sheet stored for 72 hours (room temperature storage) in a thermostatic chamber at a temperature of 23 ° C. and a humidity of 50% RH.
Further, after the sheet was stored in a hot air dryer at 60 ° C. for 72 hours, the folding strength of the sheet left for 3 hours in a thermostatic chamber at a temperature of 23 ° C. and a humidity of 50% RH was also measured.
[Loss coefficient tanδ peak value]
The temperature dependence of dynamic viscoelasticity was measured for each of the longitudinal and lateral directions of the sheet. The peak value of the loss coefficient tanδ in the main dispersion temperature region was read from the obtained dynamic viscoelastic temperature dependence curve.
[Sheet rigidity]
In accordance with JIS K6734-1995, No. 1 dumbbell-shaped specimens were used, and the tensile modulus in each of the longitudinal and transverse directions of the sheet was measured at a test speed of 50 mm / min.
Further, the tensile yield point strength in the machine direction and the transverse direction of the sheet was measured by the same test method as described above.
[Shock resistance]
In accordance with JIS K7160 (A method), a type 3 test piece was used, the crosshead mass was 30 g, the potential energy before swinging down the striker was 4 J, and the tensile impact strength in the longitudinal and lateral directions of the sheet was measured.
[Heat-resistant]
The above sheet was formed into a plate having a thickness of 1 mm, and the flexible temperature was measured according to JIS K6773-1999.
[transparency]
The haze of the sheet was measured according to JIS K7105-1981.
Further, the total light transmittance of the sheet was measured by the same test method as described above.

The sheet produced above was molded to produce an embossed carrier tape. The moldability and the characteristics of the resulting embossed carrier tape were evaluated as follows. The evaluation results are shown in Tables 3 and 4.
[Embossing formability]
Using a press molding machine, heat a long strip-shaped slit sheet with a width of 24 mm × thickness 0.4 mm to a surface temperature of 110 to 150 ° C, and a bottomed hollow with a bottom of 13 mm × width 13 mm × height 10 mm and a square bottom A shaped pocket was formed at a pitch of 3 mm along the length direction. A feed hole for φ1.5mm positioning was punched out.
The case where the pocket portion and flange portion of the embossed carrier tape thus obtained satisfy the predetermined dimensions and shape is “◯”. The case of not satisfying the dimension shape was evaluated as “×”.
[Pocket strength]
Separate the pockets of the resulting embossed carrier tape one by one, place them horizontally on the table of the compression tester with the pocket openings facing downwards, and use a circular jig to make the entire pocket bottom 1 mm vertically at a speed of 20 mm / min. The maximum load point at that time was defined as the pocket strength. When the pocket strength was 2.0 kgf or more, “◯” was evaluated, and when the pocket strength was 2.0 kgf or less, “×” was evaluated. If the pocket part strength is 2.0 kgf or more, the pocket part is not easily crushed and is suitable for practical use.
[Punching property]
Check the φ1.5mm punch hole (feeding hole for positioning) of the resulting embossed carrier tape by visual inspection. If there is no burr, “○”, if it is burr, “×”. evaluated.
[Folding resistance of carrier tape]
The obtained embossed carrier tape is stored for 72 hours in a temperature-controlled room with a temperature of 23 ° C. and a humidity of 50% RH (room temperature storage), and the flange portion between the pockets is 180 ° so that the openings of adjacent pockets face each other. The case where the flange was not cracked was evaluated as “◯”, and the case where it was cracked was evaluated as “X”.
Further, an embossed carrier tape that was stored for 72 hours in a hot air dryer at 60 ° C. and then left for 3 hours in a thermostatic chamber at a temperature of 23 ° C. and a humidity of 50% RH was similarly evaluated.

As is clear from Tables 1 to 4, it can be seen that the physical properties of the sheet and embossed carrier tape of this example are realized in a well-balanced and high-dimensional manner.
However, in Comparative Example 1 with a small amount of styrene-conjugated diene block copolymer (B), the folding strength is inferior, and in Comparative Example 2 with a small amount of styrene-conjugated diene block copolymer (A), rigidity and heat resistance temperature are reduced. Comparative Example 3 without these styrene-conjugated diene block copolymers (A) and (B) is inferior in folding strength, moldability and the like. Comparative Example 4 with a small amount of polystyrene resin (C) is inferior in heat resistance, strength, etc., whereas excessive Comparative Example 5 is inferior in folding strength, impact resistance, etc. Comparative Example 6 without the impact-resistant polystyrene resin (D) was inferior in impact resistance, whereas excessive Comparative Example 7 was inferior in transparency and strength.

Claims (2)

Styrene-conjugated diene block copolymer (A), styrene-conjugated diene block copolymer (B) other than the styrene-conjugated diene block copolymer (A), polystyrene resin (C), and impact-resistant polystyrene resin Containing (D),
The styrene-conjugated diene block copolymer (A) has a styrene monomer content of 65 to 85% by mass, and the conjugated diene block contains 75% by mass or more and 100% by mass of a conjugated diene homopolymer or conjugated diene. It is a copolymer composed of a conjugated diene and a styrenic monomer containing less than
The styrene-conjugated diene block copolymer (B) has a styrene monomer content of 65 to 85% by mass, and the conjugated diene block contains conjugated diene in an amount of 50% by mass to less than 75% by mass. And a styrene monomer copolymer,
The peak molecular weight of the styrene block of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) is in the range of 30,000 to 80,000, and the molecular weight distribution curve of the styrene block is half of The price range is 1.3 to 3.0,
The mass ratio (A / B) of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B) is in the range of 95/5 to 25/75,
The content of the polystyrene resin (C) is 20 to 110 parts by mass with respect to a total of 100 parts by mass of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B),
The content of the impact-resistant polystyrene resin (D) is 5 to 35 parts by mass with respect to a total of 100 parts by mass of the styrene-conjugated diene block copolymer (A) and the styrene-conjugated diene block copolymer (B). A sheet comprising a styrenic resin composition. An embossed carrier tape formed by molding the sheet according to claim 1.