JPH0340071B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an adhesive tape. More specifically, the present invention relates to an adhesive tape that is difficult to break even when the adhesive tape is used, especially during high-speed and impactful withdrawal at a large withdrawal angle. [Prior Art] So-called polyester adhesive tapes, which are polyethylene terephthalate films with adhesive layers on one or both sides, are widely used for general industrial purposes and electrical insulation. The reason is that polyester film has better properties such as mechanical strength, dimensional stability, abrasion resistance, chemical resistance, water resistance, transparency, and electrical insulation than other synthetic resin films such as polyprolene and polyvinyl chloride. , because it is much better than cellophane etc. However, even polyester films that seem to be versatile at first glance have drawbacks. When using a tape that is wound in concentric circles, such as cellophane tape, the tape can be easily removed by increasing the pulling angle of the tape (180° peeling in extreme cases) and performing a high-speed impact pulling (peeling) operation. Cut into. In particular, when the adhesive strength is increased so that a large force is applied during peeling, there is a marked tendency to easily break the adhesive. This breaking phenomenon cannot be expected from the general concept that polyester film is strong, but when the fracture surface is observed in detail using a scanning electron microscope, it is found that layered fracture occurs in the plane or diagonal direction of the polyester film. This is thought to be the cause of the amputation. This is probably because the strength in the thickness direction of the polyester film decreases due to the so-called plane orientation phenomenon in which specific planes of crystals are oriented in a certain direction when the polyester film is biaxially stretched. Furthermore, another property demanded by the market for adhesive tapes is an increase in adhesive strength, and the above-mentioned improvements are an essential condition for meeting this demand. As the adhesive force increases, distortion concentrates on the base film when the tape is pulled out, and the demand for impact resistance of the base film has become even higher. Incidentally, polyester films are generally required to have good winding properties and processability, and for this purpose, it is necessary that the coefficient of friction of the polyester film is low. Conventionally, as a technique for reducing the coefficient of friction of a film, protrusions are added to the surface of the film by stretching a polymer to which inorganic particles are added or a polymer in which insoluble catalyst residue particles are formed. It has become customary. Voids are usually formed around these particles in the stretched film, and these voids are one of the causes of laminar fracture, which is the cause of breakage when the tape is drawn out. That is, the cutting of the polyester adhesive tape due to layered destruction occurs due to the high plane orientation of the polyester film and the voids around the inorganic particles added or generated in the film. This plane orientation can be reduced by lowering the stretching ratio during production of the polyester film, but this method results in a decrease in the tensile strength of the polyester film, an increase in thickness unevenness, etc. It is also possible to improve the cutting caused by laminar breakage by reducing the amount of inorganic particles in the film, but this method reduces the winding properties of the film. [Object of the Invention] The object of the present invention is to solve the problems of the prior art described above, and to provide an excellent adhesive tape that does not break even when the tape is pulled out at a large angle and subjected to a high-speed impact pulling operation. The purpose of the present invention is to provide adhesive tape economically. [Structures and Effects of the Invention] According to the present invention, an adhesive tape comprising a biaxially oriented polyester film coated with an adhesive layer on at least one side, wherein the polyester film has a structure in the polyester. unit of 80
Silicone resin fine particles with a volume shape coefficient of 0.20 to 0.52 and an average particle size of 0.1 to 4 μm, which are composed of trifunctional organosiloxane represented by CH ₃・SiO _3/2 in a proportion of 0.03 to 1.0% by weight or more, are This is achieved by an adhesive tape characterized in that it is a film containing % by weight. The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyester is substantially linear;
It also has film-forming properties, particularly film-forming properties by melt molding. Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, dipheninoxyethane dicarboxylic acid, diphenidicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthraphthalic acid. Examples include sendicarboxylic acid and the like. Examples of aliphatic glycols include polymethylene glycols having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, or alicyclic glycols such as cyclohexanedimethanol. Diols and the like can be mentioned. In the present invention, polyesters containing, for example, alkylene terephthalate and/or alkylene naphthalate as a main component are preferably used. Among such polyesters, for example, polyethylene terephthalate, polyethylene-2,6-
Not only naphthalate but also terephthalic acid and/or terephthalic acid and/or
or 2,6-naphthalene dicarboxylic acid, and a copolymer in which 80 moles or more of the total glycol component is ethylene glycol is preferred. At that time, the total acid component
Up to 20 mol % of the dicarboxylic acid can be the aromatic dicarboxylic acids mentioned above, and can also be, for example, aliphatic dicarboxylic acids such as adipic acid and sebacic acid; alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid, etc. Something can happen. In addition, 20 mol% or less of the total glycol component can be the above glycol other than ethylene glycol,
Alternatively, aromatic diols such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane; alicyclic diols containing aromatics such as 1,4-dihydroxymethylbenzene; polyethylene glycol, polypropylene glycol, It can also be polyalkylene glycol (polyoxyalkylene glycol) such as tetramethylene glycol. In addition, the polyester used in the present invention includes, for example, an aromatic oxyacid such as hydroxybenzoic acid;
Also included are those in which a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as -hydroxycaproic acid is copolymerized or combined in an amount of 20 mol % or more based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component. Furthermore, the polyester in the present invention has a substantially linear amount, e.g.
Also included are copolymerized polycarboxylic acids or polyhydroxy compounds of trifunctional or higher functionality, such as trimellitic acid and pentaerythritol, in an amount of mol % or less. The above polyester is known per se, and can be produced by a method known per se. The polyester preferably has an intrinsic viscosity of 0.4 to about 0.9 as measured as a solution in o-chlorophenol at 35°C. The biaxially oriented polyester film of the present invention has many fine protrusions on its surface.
According to the present invention, those many fine protrusions are derived from a large number of silicone resin fine particles dispersed and contained in the polyester. Polyester containing dispersed silicone resin particles can be produced at any time during the reaction to form polyester, for example, during the transesterification reaction or polycondensation reaction when using the transesterification method, or at any time during the polycondensation reaction when using the direct polymerization method. It can be produced by adding silicone resin fine particles (preferably as chiller in glycol) to the reaction system. Preferably, silicone resin fine particles are added to the reaction system at the beginning of the polycondensation reaction, for example, until the intrinsic viscosity reaches about 0.3. In the present invention, the silicone resin fine particles contained in the polyester are composed of trifunctional organopolysiloxane in which 80% by weight or more of the structural units are represented by CH ₃ · SiO _3/2 , and the volume shape coefficient is
These are silicone resin fine particles having a size of 0.20 to 0.52 and an average particle size of 0.1 to 4 μm. The above structural unit composition CH3・
SiO _3/2 is the unit structural formula The above-mentioned organopolysiloxane is an organopolysiloxane having a three-dimensional bond structure in which 80% by weight or more of its structural units are represented by (CH ₃ .SiO _3/2 )n. Here, the above n represents the degree of polymerization, and is preferably 100 or more. Other components include bifunctional organopolysiloxane or other trifunctional organopolysiloxane derivatives. The silicone resin fine particles have excellent lubricity, have a lower specific gravity than inorganic inert fine particles, and have better heat resistance than organic fine particles, and are insoluble in organic solvents, It also has the characteristic of being non-melting. Furthermore, silicone resin fine particles exhibit excellent affinity for polyester. The silicone resin fine particles used in the present invention have an average particle size of 0.1 to 4 μm, preferably 0.1 to 2 μm, and more preferably 0.8 to 2 μm. Average particle size is 0.1μ
If it is less than 4 μm, the effect of improving slipperiness and processing suitability (winding properties, etc.) will be insufficient, while if it exceeds 4 μm, the cut resistance will be insufficient, which is not preferable. The average particle size referred to here is the sum of the equivalent spherical diameter particle size distribution calculated based on Stokes' formula 50
It is expressed as a diameter at a % point. In order to obtain particles with a predetermined average particle size, pulverization treatment or classification operation of commercially available silicone resin fine particles may be employed. Furthermore, the silicone resin fine particles have a volume shape coefficient of 0.20 to 0.52. By providing such characteristics, the slipperiness of the biaxially oriented polyester film is extremely excellent, and the layered fracture of the biaxially oriented polyester film is improved due to the affinity of the silicone resin particles for polyester. be done. Generally, polyester and inorganic fine particles have no affinity. Therefore, when a melt-formed unstretched polyester film is biaxially stretched, peeling occurs at the boundary between the particles and the polyester, and voids are formed around the fine particles. These voids are more likely to occur as the fine particles are larger, as the shape is closer to a spherical shape, as the fine particles become a single particle and are less likely to deform, and as the stretching area ratio increases when stretching an unstretched film, and as the stretching is carried out at a constant temperature. growing. The larger the void, the more gradual the shape of the protrusion becomes, increasing the coefficient of friction and deteriorating the laminar fracture resistance. In the case of conventional inorganic inert lubricants,
The amount of voids around the lubricant is quite large, and in high-strength polyester films, these voids become even larger.As a result, the biaxially oriented film becomes more susceptible to delaminar destruction, and adhesive tapes using such polyester films are difficult to cut during high-speed drawing. Occurs frequently. However, since the silicone resin fine particles in the present invention have an affinity for polyester, no voids are formed, or even if voids are formed, they are very small. Therefore, the adhesive tape based on the biaxially oriented polyester film of the present invention is unlikely to be cut due to laminar destruction during high-speed drawing. In the present invention, the amount of silicone resin fine particles added is 0.03 to 1.0% by weight based on the polyester.
The amount should be 0.1 to 0.5% by weight, preferably 0.1 to 0.5% by weight. If the amount added is less than 0.03% by weight, the effect of improving winding properties and processability will be insufficient, while if it exceeds 1.0% by weight, cut resistance will decrease, which is not preferable. The silicone resin fine particles are not limited in any way in terms of their manufacturing method or other aspects as long as they satisfy the above conditions. In the biaxially oriented polyester film of the present invention, when the surface of the film is ion-etched to expose the silicone resin fine particles in the film and the surface is observed with a scanning electron microscope, it is found that most of the silicon in the biaxially oriented polyester film is No voids are observed around the resin particles. This is surprising when compared to the void generation situation in the case of inorganic fine particles such as kaolin. Note that this can also be easily observed by transmission observation using an optical microscope. Due to the absence of voids in this way,
A biaxially oriented polyester film with excellent laminar fracture resistance is obtained. In particular, even in the case of a high-strength polyester film that has been stretched to a high magnification and has an increased Young's modulus, there are almost no or no voids. The biaxially oriented polyester film of the present invention can be produced according to conventional methods for producing biaxially oriented films. For example, polyester containing silicone resin fine particles is melt-formed to form an amorphous unstretched film, then the unstretched film is stretched biaxially, heat set, and if necessary subjected to relaxation heat treatment. It is manufactured by At this time, the film properties vary depending on the shape, particle size, amount, etc. of the silicone resin fine particles, and also depending on the stretching conditions, so they are appropriately selected from conventional stretching conditions. Furthermore, since voids, density, thermal shrinkage rate, etc. change depending on the temperature, magnification, speed, etc. during stretching and heat treatment, conditions are determined to satisfy these characteristics at the same time. for example,
The stretching temperature ranges from the first-stage stretching temperature (e.g. longitudinal stretching temperature: T ₁ ) in the range of (Tg-10) to (Tg+45)°C (where Tg is the glass transition temperature of polyester) to the second-stage stretching temperature ( For example, transverse stretching temperature:
T ₂ ) is preferably selected from the range of (T ₁ +15) to (T ₁ +40)°C. Further, the stretching ratio is preferably selected from a range in which the stretching ratio in the uniaxial direction is 2.5 times or more, particularly 3 times or more, and the area magnification is 8 times or more, especially 10 times or more. Furthermore, the heat setting temperature is preferably selected from the range of 180 to 250°C, more preferably 200 to 230°C. In the present invention, the adhesive layer coated on at least one side of the above-mentioned biaxially oriented polyester film is
It can be formed using conventional adhesive tape making methods and adhesives. As the adhesive, for example, a rubber-based, vinyl ether-based, acrylic polymer, etc. may be used, and a hot melt type adhesive may be used. As a coating method, a method such as applying and drying an organic solvent or emulsion may be used, or a material such as ethylene-vinyl acetate copolymer may be coated by a melt extrusion method and this may be used as an adhesive. The pressure-sensitive adhesive may be applied to one side, but when producing a double-sided pressure-sensitive adhesive tape, the pressure-sensitive adhesive may be applied to both sides. An adhesive may be applied to one side, and a silicone-based mold release agent may be applied to the other side. However, the adhesive type, application method, etc. are not limited to these. The pressure-sensitive adhesive tape of the present invention may be provided with other layers such as a colorant layer, if desired. Various physical property values and characteristics in the present invention were measured and defined as follows. (1) Average particle size of particles Measured using a Shimadzu Corporation CP-50 Centrifugal Particle Size Analyzer. The particle size corresponding to 50 mass percent was read from the cumulative curve of particles of each particle size and their abundance calculated based on the obtained stretching sedimentation curve, and this value was taken as the above average particle size. (See "Particle Size Measurement Techniques," published by Nikkan Kogyo Shimbun, 1975, Mitsugu 242-247). (2) Film surface roughness (Ra) Center line average roughness: JIS as Ra (unit: μm)
- This is the value defined in B0601. In the present invention, a stylus type surface roughness meter (SURFCORDER SE-30C) manufactured by Kosaka Research Institute Co., Ltd. is used.Stylus radius: 2μm, measurement pressure: 0.03g, cutoff value:
A film surface roughness curve is drawn under the condition of 0.25 mm, and a part of measurement length L is extracted from the film surface roughness curve in the direction of its center line. When the roughness curve is expressed as Y=f(x) with the direction of Y axis, the value given by the following formula (Ra: μm)
is defined as the film surface roughness. Ra=1/L∫ ^L ₀ |f(x)|dx Five samples were measured with a reference length of 2.5 mm, and Ra was expressed as the average value of the four samples, excluding the one with the largest value. (3) Volume shape factor f Photographs of silicone resin microparticles were taken using a scanning electron microscope at 5000x magnification for 10 fields of view, and an image analysis processing device Luzetx 500 (manufactured by Nippon Regulator) was used.
Calculate the average value of the maximum diameter for each field of view using
Furthermore, calculate the average value of 10 visual fields and define it as D. Using the average particle diameter d of the particles determined in the above item (1), the volume of the particles is calculated by V=π/6d ³ , and the shape factor f is calculated by the following formula. f=V/D In ^the formula, V represents the volume of the particles (μm ³ ), and D represents the maximum diameter of the particles (μm). (4) Void The surface of the film is ion-etched to expose the fine particles in the film.
Aluminum is uniformly vacuum-deposited to a thickness of 400 to 500 Å or more using a regular scanning electron microscope.
The surface was observed at 3500 times to 5000 times magnification, and the long axis of the solid fine particles and the long axis of the voids were measured, and the ratio of (void long axis)/(solid fine particle long axis) was defined as the void ratio. The number of measurements was 40, and the average value was expressed. Ion etching is, for example, manufactured by JEOL Ltd.
The surface was etched using a JFC-1100 ion sputtering device at 500V and 12.5mA for 15 minutes. The degree of vacuum was 10 ^-3 Torr. (5) Haze (cloudiness) The haze of the film was determined using an integrating sphere HTR meter manufactured by Nippon Seimitsu Kogaku Co., Ltd. in accordance with JIS-K674. (6) Pull-out cutting properties of tape A concentrically wound adhesive tape was manually subjected to high-speed impact peeling 20 times in the opposite direction to the pull-out direction (180° peeling), and the number of breaks The evaluation is as follows. 0 to 2 times: ○ (very good) 3 to 6 times: △ (slightly good) 7 times or more: × (poor, equivalent to the current level) (7) Winding property In the manufacturing process of biaxially oriented polyester film, film is rolled up into a 4000m roll with a width of 5000mm, the appearance of this roll is inspected in detail, the number of lump-like protrusions with a major diameter of 2mm or more is counted, and the rolls are graded as follows: 0 to 2: ○ 3 to 5: △ 6 or more: × [Examples] The present invention will be explained in more detail with reference to Examples. Reference Examples 1, 2 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and kaolin with an average particle size of 1.2 μm and a volume shape coefficient of 0.06 as a lubricant. Polyethylene terephthalate with an intrinsic viscosity of 0.62 was obtained by polymerization using a conventional method. The amount of kaolin added is 0.1 and 0.03, respectively.
It was expressed as weight%. These polyethylene terephthalate (hereinafter
PET (abbreviated as PET) pellets are dried at 170℃ for 3 hours, then fed into the extruder hopper, melted at a melting temperature of 280 to 300℃, and passed through a 1 mm slit-shaped die with a surface finish of about 0.3S and a surface temperature of 20℃. The film was formed and extruded on a rotating cooling drum to obtain an unstretched film of 300 μm. The unstretched film thus obtained was heated at 75°C.
The material was preheated at , then heated with one IR heater with a surface temperature of 900°C from 15 mm above between low-speed and high-speed rolls, stretched 3.5 times in the longitudinal direction, rapidly cooled, and then fed to a stenter to 105°C. The film was stretched 3.7 times in the transverse direction. The obtained biaxially stretched film was heat set at a temperature of 205° C. for 5 seconds to obtain a heat set biaxially stretched film having a thickness of 23 μm. The obtained film has a void ratio
It was 1.7. The properties of this film are shown in Table 1. Reference Examples 3 to 10 Comparison except that silicone resin fine particles (fine particles prepared using Toshiba product name XC99-301, -501) prepared to the average particle size and volume shape coefficient shown in Table 1 were used instead of kaolin. Polyethylene terephthalate pellets were obtained in the same manner as in Examples 1 and 2. A heat-set biaxially oriented film having a thickness of 23 μm was obtained in the same manner as in Comparative Examples 1 and 2 except that the pellets were used. The properties of this film are shown in Table 1.
All films obtained in this reference example were of excellent quality. Examples 1 to 7 and Comparative Examples 1 to 3 After corona treatment was applied to one side of each of the films obtained in Reference Examples 1 to 10, a toluene solution containing natural rubber and polyterpene resin as main components (adhesive agent concentration 25% by weight) (approximately 8μ
m) After drying in hot air at 90°C, the slits were slit to a width of 19 mm, and cuttability was evaluated using a form similar to commercially available cellophane tape. The results are shown in Table 1. As is clear from this table, tapes that satisfy the conditions of the present invention have a small number of tape pull-out cuts and excellent winding properties.

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Claims (1)

[Claims] 1. An adhesive tape comprising a biaxially oriented polyester film coated with an adhesive layer on at least one side, wherein the polyester film has a composition in which 80% by weight or more of the structural units in the polyester are CH ₃・SiO _3/2
Silicone resin fine particles made of trifunctional organosiloxane represented by the formula and having a volume shape coefficient of 0.20 to 0.52 and an average particle size of 0.1 to 4 μm are 0.03 to 1.0 μm.
An adhesive tape characterized by being a film containing % by weight.