JP7456175B2 - laminated polyester film - Google Patents

Description

The present invention relates to a laminated polyester film having a coating layer on the surface of the polyester film.

Polyester films have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and are excellent in cost performance, so they are used for various purposes.

In recent years, properties other than those listed above have become required due to the diversification of uses for polyester films. For example, when polyester films are used for semiconductor molding processes, in addition to the above properties, properties other than those listed above are also required. There are cases where it is required to improve the releasability of the polyester film and to suppress the transfer of the oligomer component (ester cyclic trimer component) contained in the polyester film to the mold.

In response to the above requirements, for example, Patent Document 1 discloses a polyester film with low surface gloss that is obtained using polyester with a low content of particles and oligomer components.

Furthermore, Patent Document 2 discloses a laminated polyester film having a coating layer containing a crosslinking agent and a mold release agent on at least one side of the polyester film, which suppresses precipitation of oligomer components on the film surface and has appropriate water repellency. is disclosed.

However, since the polyester film described in Patent Document 1 uses polyester having a high intrinsic viscosity, extrusion molding becomes difficult, and there is a concern that production efficiency may deteriorate. Furthermore, since the polyester film comes into direct contact with the mold in the semiconductor molding process, there is also concern that releasability and suppression of transfer of oligomer components to the mold may not be sufficient.
Further, although the laminated polyester film described in Patent Document 2 can suppress the precipitation of oligomer components on the film surface, there is concern that the transfer of the oligomer components to the mold is not sufficiently suppressed.

JP2017-179334A JP 2016-30378 Publication

The present invention has been made in view of the above circumstances, and an object to be solved is to provide a laminated polyester film in which contamination by oligomer components is suppressed, for example, in a laminated polyester film used in a semiconductor molding process.

In view of the above-mentioned circumstances, the present inventors have conducted extensive studies and found that the above-mentioned problems can be easily solved by using a laminated polyester film having a specific configuration, and have completed the present invention. .

In other words, the gist of the present invention is a laminated polyester film having a coating layer on at least one surface of a polyester film, the coating layer being formed from a coating liquid containing wax, the wax occupying 1% by mass or more and 40% by mass or less of the total non-volatile components in the coating liquid, and the softening point of the wax being 90°C or higher.

According to the present invention, it is possible to provide a laminated polyester film in which contamination by oligomer components is suppressed when used as a release film for a semiconductor molding process, for example.

An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiment described below, and can be modified as desired without departing from the gist of the present invention.

The polyester film constituting the laminated polyester film of the present invention may have a single layer structure or a multilayer structure. In the case of a multilayer structure, it may be a two-layer structure, a three-layer structure, etc., or may be a multilayer structure of four or more layers without departing from the gist of the present invention, and the number of layers is not particularly limited. Further, the polyester film is preferably a biaxially stretched polyester film.

The polyester used may be a homopolyester or a copolyester.
When consisting of a homopolyester, one obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol is preferable. Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalene dicarboxylic acid, and examples of aliphatic glycols include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate and the like.
On the other hand, the dicarboxylic acid component of the copolymerized polyester includes one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid, Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, neopentyl glycol, and the like. From the viewpoint of effectively increasing the surface roughness of the polyester film, it is preferable that the third component contained is isophthalic acid.
The copolymerized polyester preferably contains a third component of 30 mol% or less, especially 5 mol% or more and 30 mol% or less, especially 25 mol% or less, and especially 7 mol% or more and 22 mol% or less. It is more preferable that By falling within this range, the surface roughness of the polyester film can be effectively increased while maintaining film formation stability.

Typical polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalene dicarboxylate (PEN), and the like.

The polyester polymerization catalyst is not particularly limited, and conventionally known compounds can be used, such as titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds, calcium compounds, etc. Among them, titanium compounds and germanium compounds have high catalytic activity and can be polymerized in small amounts. Therefore, since the amount of metal remaining in the film is small, absorption of light transmitted through the laminated polyester film is suppressed, and the brightness of the laminated polyester film is increased. Furthermore, since germanium compounds are expensive, it is more preferable to use titanium compounds.

In the case of polyester using a titanium compound, the titanium element content in the polyester film is preferably 50 ppm or less, more preferably 1 to 20 ppm, and even more preferably 2 to 10 ppm. In addition, when the polyester film is multilayered, the titanium element content in each layer is preferably within the above range. By setting the content of the titanium compound to the above upper limit value or less, deterioration of the polyester can be prevented in the process of melt-extruding the polyester, and a film with a strong yellowish tinge can be prevented. Moreover, when the content is equal to or more than the above lower limit, the polymerization efficiency becomes good, the cost becomes low, and it becomes easy to obtain a film having sufficient strength.

When using polyester containing a titanium compound, it is preferable to blend a phosphorus compound into the polyester in order to reduce the activity of the titanium compound for the purpose of suppressing deterioration during the melt extrusion process. As the phosphorus compound, alkyl acid phosphates such as orthophosphoric acid and ethyl acid phosphate are preferable in consideration of the productivity and thermal stability of polyester.
The phosphorus element content in the polyester film is preferably in the range of 1 to 300 ppm, more preferably 3 to 200 ppm, and still more preferably 5 to 100 ppm. By controlling the content of the phosphorus compound to be less than or equal to the above upper limit, it is possible to prevent the phosphorus compound from causing gelation or foreign matter. Further, by setting the amount to be equal to or more than the above lower limit, the activity of the titanium compound can be sufficiently lowered, and a yellowish film can be prevented.
Note that when the polyester film is multilayered, the phosphorus element content in the layer containing titanium element is preferably within the above range.

In the present invention, in order to suppress the amount of oligomer components precipitated, the film may be manufactured using polyester having a low content of oligomer components as a raw material. As a method for producing polyester with a low content of oligomer components, various known methods can be used, such as a method in which solid phase polymerization is performed after producing polyester.
Further, the amount of precipitation of the oligomer component may be suppressed by forming the polyester film to have a structure of three or more layers, and making the outermost layer of the polyester film a layer using a polyester raw material with a low content of the oligomer component.
Further, polyester may be obtained by performing esterification or transesterification reaction and then further increasing the reaction temperature and performing melt polycondensation under reduced pressure.

When the laminated polyester film of the present invention is used as a release film for a semiconductor molding process, the polyester film preferably includes a particle-containing layer A in order to improve release properties from a mold.
When the polyester film of the present invention includes the particle-containing layer A, the polyester film may have a structure consisting only of the particle-containing layer A, or the particle-containing layer A may be provided on one side or both sides of the base layer. It may be equipped with the following. As a specific example of the latter, for example, the base material layer may have the particle-containing layer A on both sides, or the base material layer may have the particle-containing layer A on one side and the other side of the base material layer. A particle-containing layer B different from the particle-containing layer A may be formed on the side, or a particle-containing layer A may be formed on one side of the base layer and a layer may be formed on the other side of the base layer. Alternatively, the particle-containing layer A may be provided on one side of the base material layer, and a layer containing no particles may be formed on the other side of the base material layer.
Among these, the polyester film has a structure in which a particle-containing layer A is provided on one side of the base layer, and a particle-containing layer B different from the particle-containing layer A is formed on the other side of the base layer, that is, a particle-containing layer. A configuration including A, a base material layer, and a particle-containing layer B in this order is preferable because curling of the film is suppressed and handling properties are good.

The particle-containing layer A, the particle-containing layer B, the base layer, and the layer not containing particles are preferably layers containing polyester as a main resin.
Here, the term "main component resin" refers to the resin having the highest content among the resin components constituting each layer.
As the polyester used in each layer, the above-mentioned polyester can be used.

Particle-containing layer A is a layer containing particles in the layer.

The average particle size of the particles contained in the particle-containing layer A is preferably 2.0 μm or more. By containing particles with an average particle size of 2.0 μm or more in the particle-containing layer A, the surface of the particle-containing layer A side of the polyester film can be roughened and matte-finished. However, if the average particle size of the particles is too large, the pressure rise of the filter in the polyester extrusion process during film production may increase, resulting in reduced productivity. Therefore, the average particle size of the particles is preferably 2.0 μm or more, and more preferably 10.0 μm or less, more preferably 3.0 μm to 9.0 μm, and even more preferably 4.0 μm to 8.0 μm.

When the particles are powder, the average particle diameter of the particles is the sum of the equivalent spherical distribution measured using a centrifugal sedimentation particle size distribution analyzer (for example, SA-CP3 model manufactured by Shimadzu Corporation). The particle size at a volume fraction of 50% (d50) can be taken as the average particle size. The average particle size of the particles in the film or layer can be determined by observing 10 or more particles using a scanning electron microscope (SEM), measuring the diameters of the particles, and determining the average value. In the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle. The same applies to particles described later.

The shape of the particles contained in the particle-containing layer A is arbitrary. For example, it may be spherical, lumpy, rod-like, flat, or the like. However, from the viewpoint of obtaining a uniform matte surface, a spherical shape is preferable.
There are no particular restrictions on the hardness, specific gravity, color, etc. of the particles, and two or more different types may be used in combination.

The particles contained in the particle-containing layer A are not particularly limited as long as they are particles that can roughen the surface of the particle-containing layer A side of the polyester film. For example, they may be inorganic particles, organic particles, or crosslinked polymer particles.
Inorganic particles are preferable from the viewpoint that they may form voids in the film when stretched and are easier to roughen, while organic particles are preferable from the viewpoint that voids are less likely to occur and the strength of the film does not decrease.

Examples of inorganic particles include silica, calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and fluoride. Examples include lithium chloride, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Note that the silica particles may contain, for example, hydrous silicon dioxide in addition to silicon dioxide (SiO ₂ ).

Examples of the organic particles include acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin.
Among these, particles made of a resin containing methyl methacrylate, styrene, or both as copolymerization components are particularly preferable because they have good compatibility with polyester films.

Examples of the crosslinked polymer particles include divinylbenzene, styrene, acrylic acid, methacrylic acid, and single or copolymers of vinyl monomers of acrylic acid or methacrylic acid. Other organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin may also be used.

The content of particles in the particle-containing layer A is set to 0 from the viewpoint of suitably roughening the surface of the particle-containing layer A side of the polyester film and preventing breakage etc. during film stretching. .1 to 20% by mass is preferable, among which 1% by mass to 18% by mass, particularly 2% by mass to 15% by mass, and even more preferably 3% by mass to 10% by mass. .

The thickness of the particle-containing layer A is preferably 1.0 to 20 μm, more preferably 2.0 μm to 20 μm, even more preferably 3.0 μm to 20 μm, and even more preferably 4.0 μm to 15 μm.
By making the thickness of the particle-containing layer A 1.0 μm or more, the surface can be effectively roughened. Also, by making the thickness of the particle-containing layer A 20 μm or less, the effect of roughening the surface can be ensured.

The relationship between the thickness of the particle-containing layer A and the average particle diameter of the particles contained in the particle-containing layer A is determined from the viewpoint of roughening the surface of the particle-containing layer A side of the polyester film and suppressing particle falling off. diameter)/(thickness of particle-containing layer A) is preferably 0.1 or more and 5.0 or less, more preferably 0.3 or more and 4.0 or less, particularly preferably 0.5 or more and 3.0 or less.

The base material layer is a layer provided with the particle-containing layer A on one surface.
The base material layer is the thickest layer among the layers constituting the polyester film, and its composition can be arbitrary as long as the above-mentioned polyester is used as the main resin.

The base material layer may be a layer containing particles or may be a layer containing no particles. However, from the viewpoint of cost, it is preferable that the layer does not contain particles such as organic particles and inorganic particles described below.

From the viewpoint of preventing the laminated polyester film from curling, the thickness of the base layer is preferably 60 to 99% of the thickness of the polyester film, particularly 65% to 99%, particularly 70% to 99%. It is more preferable that it is as follows. By falling within this range, the base material layer itself becomes stiff, making it difficult for the laminated polyester film to curl.

The particle-containing layer B is a layer laminated on the other side of the base layer having the particle-containing layer A on one side.
Particle-containing layer B preferably contains particles with an average particle diameter of 2.0 μm or more, and has an average surface roughness (Ra) of 0.02 μm, from the viewpoint of handling properties and preventing curling of the entire polyester film. It is preferable that it is above.

The particles used in the particle-containing layer B include particles having the same shape and type as those used in the particle-containing layer A, for example.

The particle content in the particle-containing layer B is preferably 0.05 to 10% by mass, and more preferably 0.1 to 18% by mass, from the viewpoints of ease of handling and prevention of curling of the entire polyester film.

Further, the content of particles used in particle-containing layer B is preferably 0.1 to 100% by mass of the content of particles contained in particle-containing layer A, particularly 1 to 95% by mass. It is more preferable that there be.

It is also possible to contain an ultraviolet absorber in the polyester film of the present invention in order to improve the weather resistance of the film and prevent deterioration of liquid crystals and the like. The ultraviolet absorber is a compound that absorbs ultraviolet rays and is not particularly limited as long as it can withstand the heat added during the polyester film manufacturing process.

As the ultraviolet absorber, there are organic ultraviolet absorbers and inorganic ultraviolet absorbers, and organic ultraviolet absorbers are preferable from the viewpoint of transparency. Examples of organic ultraviolet absorbers include, but are not limited to, cyclic imino esters, benzotriazoles, benzophenones, and the like. From the viewpoint of durability, cyclic iminoester type and benzotriazole type are more preferable. It is also possible to use two or more types of ultraviolet absorbers in combination.

The method of adding particles into the polyester layer is not particularly limited, and any conventionally known method may be employed. For example, it can be added at any stage of producing the polyester constituting each layer, but it is preferably added after the esterification or transesterification reaction is completed.

The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed into a film, but is usually in the range of 10 to 350 μm, preferably 25 to 250 μm.

Next, a specific example of the production of the polyester film of the present invention will be described, but the production example is not limited to the following. That is, a method in which the above-mentioned polyester raw material is dried and pellets are extruded from a die using an extruder as a molten sheet, and cooled and solidified by a cooling roll to obtain an unstretched sheet is preferred. In this case, it is preferable to increase the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and an electrostatic application adhesion method and/or a liquid application adhesion method are preferably used. Next, the obtained unstretched sheet is stretched in a biaxial direction. In this case, the unstretched sheet is first stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the sheet is stretched in a direction perpendicular to the first-stage stretching direction, in which the stretching temperature is usually 70 to 170°C, and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. The film is then heat-treated at a temperature of 180 to 270°C under tension or relaxation of 30% or less to obtain a biaxially oriented film. In the above stretching, a method of stretching in one direction in two or more stages can also be used. In that case, it is preferable to perform the stretching so that the final stretch ratios in both directions are within the above ranges.

A simultaneous biaxial stretching method can also be used to manufacture polyester films. The simultaneous biaxial stretching method involves simultaneously stretching and orienting the unstretched sheet in the machine direction and width direction under temperature control, usually at 70 to 120°C, preferably 80 to 110°C, with the stretching ratio being 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in area. The sheet is then heat-treated under tension or relaxation of 30% or less at a temperature of 170 to 250°C to obtain a stretched and oriented film. As for the simultaneous biaxial stretching device employing the above-mentioned stretching method, any conventionally known stretching method, such as a screw method, a pantograph method, or a linear drive method, can be used.

Next, the formation of the coating layer constituting the laminated polyester film of the present invention will be explained. Although the method for forming the coating layer is not particularly limited, it is preferably formed by in-line coating, in which the surface of the film is treated during the polyester film forming process.

In-line coating is a method in which coating is performed within the process of polyester film production, and specifically, coating is performed at any stage from melt extrusion of polyester to stretching, heat setting, and winding. Usually, the coating is applied to either an unstretched sheet obtained by melting and quenching, a stretched uniaxially oriented film, a biaxially oriented film before heat setting, or a film after heat setting but before winding. Although not limited to the following, for example, in sequential biaxial stretching, a method in which a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is coated and then stretched in the transverse direction is particularly excellent. According to this method, film formation and coating layer formation can be performed at the same time, which is advantageous in terms of manufacturing costs. Since stretching is performed after coating, the thickness of the coating layer can be changed by changing the stretching ratio, and thin film coating can be performed more easily than offline coating films. Further, by providing a coating layer on the film before stretching, the coating layer can be stretched together with the polyester film, thereby making it possible to firmly adhere the coating layer to the polyester film. Furthermore, in the production of biaxially oriented polyester film, by holding the edges of the film with clips and stretching it, the film can be restrained in the vertical and horizontal directions, and the film can be flattened without wrinkles during the heat setting process. Can be heated to high temperatures while maintaining its properties. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film-forming properties of the coating layer are improved, and the coating layer and the polyester film can be bonded more firmly. Furthermore, it is possible to form a strong coating layer, and it is possible to improve performance such as adhesion with various functional layers that may be formed on the coating layer and heat-and-moisture resistance.

Next, the coating layer in the present invention will be described. In the present invention, a coating layer is provided on at least one surface of the polyester film, and the coating layer is formed from a coating liquid containing wax, and the wax accounts for 1% by mass of the total nonvolatile components in the coating liquid. The essential requirements are that the content is 40% by mass or less and that the softening point of the wax is 90°C or higher.

The coating layer provided on the surface of the polyester film in the present invention can suppress contamination caused by oligomer components precipitated from the polyester film by heating, and can also be referred to as a layer for suppressing contamination caused by oligomer components. The laminated polyester film of the present invention can be suitably used, for example, as a protective film for processes.

When the polyester film in the present invention has a particle-containing layer A, it is preferable that the film has a coating layer on the surface of the particle-containing layer A. When the polyester film consists of only the particle-containing layer A or has particle-containing layers A on both sides of the base layer, it is preferable that the film has a coating layer on at least one of the surfaces of the particle-containing layer A.
A more preferred configuration is one in which a polyester film has a particle-containing layer A, a base layer and a particle-containing layer B in this order, and a coating layer is provided on the surface of the particle-containing layer A.
When the laminated polyester film having the above-mentioned configuration is used as a release film for a semiconductor molding process, it is possible to improve the releasability from a mold and prevent the transfer of oligomer components to the mold, thereby suppressing process contamination.

In addition, the oligomer component in this invention is a low molecular weight component of polyester which precipitates on the surface of a polyester film by heating, and refers to an ester cyclic trimer component.

Wax is a wax selected from natural waxes, synthetic waxes, and blended waxes.

The natural waxes mentioned above include vegetable waxes, animal waxes, mineral waxes, and petroleum waxes. Examples of vegetable waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Animal waxes include beeswax, lanolin and spermaceti. As mineral waxes, mention may be made of montan wax, ozokerite and ceresin. As petroleum waxes, mention may be made of paraffin wax, microcrystalline wax and petrolatum.

Examples of the synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, ester waxes, and ketones.

Specifically, Fischer-Tropsch wax (also known as Sozoir wax) and polyethylene wax are famous as synthetic hydrocarbons. The following polymers, which are polymers), are also included: That is, there are polypropylene, ethylene/acrylic acid copolymer, polyethylene glycol, polypropylene glycol, and block or graft combinations of polyethylene glycol and polypropylene glycol.

Specific examples of the modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative here is a compound obtained by any one of purification, oxidation, esterification, and saponification, or a combination thereof.

Specific examples of the hydrogenated wax include hydrogenated castor oil and hydrogenated castor oil derivatives.

Among these waxes, synthetic hydrocarbon waxes are preferred because they provide stable performance and are easily available. Polyethylene wax, polypropylene wax, oxidized polyethylene wax, and oxidized polypropylene wax are more preferred because they can effectively suppress contamination by oligomer components, with polyethylene wax and oxidized polyethylene wax being particularly preferred.

The softening point of the wax in the present invention is preferably 90°C or more and 170°C or less, more preferably 100°C or more and 160°C or less, and even more preferably 120°C or more and 150°C or less. By using a wax having a softening point within this range, it is possible to improve releasability when used as a protective film for a process, for example, and to suppress contamination of the process due to oligomer components contained in the polyester film.
From the viewpoint of suppressing precipitation of oligomer components and suppressing process contamination due to oligomer components, particularly preferred are polyethylene waxes and oxidized polyethylene waxes having a softening point of 90° C. or higher.
The softening point of wax can be measured and calculated in accordance with JIS-K2207.

The mechanism by which the use of wax prevents contamination by oligomer components contained in polyester film is believed to be as follows. When polyester film is heated above its glass transition point, oligomer components precipitate on its surface. As they pass through a coating layer containing wax during the process of precipitating on the surface, the wax has a high affinity for the oligomer components, and the surface of the oligomer components is coated with the wax. This not only prevents the oligomer components from crystallizing and prevents their precipitation, but it is speculated that the wax on the surface reduces adhesion to processing equipment such as molds, thereby preventing process contamination.

In the coating layer of the present invention, a crosslinking agent is preferably used in combination to improve adhesion to the polyester film and to strengthen the coating film. Examples of crosslinking agents include melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, and isocyanate compounds. Among these, melamine compounds, oxazoline compounds, and epoxy compounds are preferred, and melamine compounds and oxazoline compounds are more preferred, as they can further suppress contamination by oligomer components contained in the polyester film.

Melamine compounds are compounds that have a melamine skeleton in the compound, such as alkylolated melamine derivatives, compounds that are partially or completely etherified by reacting an alkylolated melamine derivative with alcohol, and mixtures thereof. can be used. As the alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, etc. are preferably used. Further, the melamine compound may be a monomer or a multimer of dimer or more, or a mixture thereof may be used. Furthermore, melamine co-condensed with urea or the like can also be used, and a catalyst can also be used to increase the reactivity of the melamine compound.

The oxazoline compound is a compound having an oxazoline group in its molecule, and a polymer containing an oxazoline group is particularly preferable, and can be prepared by polymerizing an addition-polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, Examples include 2-isopropenyl-4-methyl-2-oxazoline and 2-isopropenyl-5-ethyl-2-oxazoline, and one type or a mixture of two or more of these can be used. Among these, 2-isopropenyl-2-oxazoline is suitable because it is industrially easily available. Other monomers are not limited as long as they are copolymerizable with the addition-polymerizable oxazoline group-containing monomer, such as alkyl (meth)acrylate (alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, (meth)acrylic acid esters such as n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene Unsaturated carboxylic acids such as sulfonic acids and their salts (sodium salts, potassium salts, ammonium salts, tertiary amine salts, etc.); Unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl ( meth)acrylamide and N,N-dialkyl(meth)acrylamide (alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group) , cyclohexyl group, etc.); Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; Vinyl chloride, vinylidene chloride, etc. Halogen-containing α,β-unsaturated monomers; examples include α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene; one or more of these monomers may be used. I can do it. From the viewpoint of improving adhesion, the amount of oxazoline groups in the oxazoline compound is preferably 0.5 to 10 mmol/g, more preferably 1 to 9 mmol/g, even more preferably 3 to 8 mmol/g, particularly preferably 4 to 6 mmol/g. g range.

An epoxy compound is a compound having an epoxy group in the molecule, such as a condensate with a hydroxyl group or an amino group such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, or a polyepoxy compound. , diepoxy compounds, monoepoxy compounds, and glycidylamine compounds. Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Examples of glycidyl ether and diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and polypropylene. Glycol diglycidyl ether and polytetramethylene glycol diglycidyl ether, monoepoxy compounds such as allyl glycidyl ether, 2-ethylhexyl glycidyl ether and phenyl glycidyl ether, glycidyl amine compounds such as N,N,N',N'-tetra Examples include glycidyl-m-xylylene diamine, 1,3-bis(N,N-diglycidylamino)cyclohexane, and the like. From the viewpoint of improving adhesion, polyether-based epoxy compounds are preferred. Moreover, as for the amount of epoxy groups, a polyepoxy compound having trifunctionality or more is more preferable than difunctionality.

A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. However, for better adhesion, etc., polycarbodiimide compounds having two or more in the molecule are more preferred.

Carbodiimide compounds can be synthesized by conventionally known techniques, and generally a condensation reaction of diisocyanate compounds is used. The diisocyanate compound is not particularly limited, and both aromatic and aliphatic types can be used. Specifically, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexane diisocyanate, etc. Examples include methylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.

The content of carbodiimide groups contained in the carbodiimide compound is usually 100 to 1000, preferably 250 to 800, more preferably 300 to The range is 700. By using it within the above range, the durability of the coating film will be improved.

Furthermore, to improve the water solubility or water dispersibility of the polycarbodiimide compound, a surfactant may be added, or a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of a dialkylamino alcohol, or a hydroxyalkylsulfonate may be added, provided that the effects of the present invention are not lost.

The isocyanate compound is a compound having an isocyanate or an isocyanate derivative structure typified by a blocked isocyanate. Examples of isocyanates include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate and naphthalene diisocyanate, and aliphatic acids having an aromatic ring such as α, α, α', α'-tetramethylxylylene diisocyanate. Aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate) and isopropylidene dicyclohexyl diisocyanate cyanate etc. Examples include alicyclic isocyanates. Also included are polymers and derivatives of these isocyanates, such as burettes, isocyanurates, uretdionates, and carbodiimide-modified products. These may be used alone or in combination. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferred than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the form of blocked isocyanate, blocking agents include, for example, bisulfites, phenol, phenolic compounds such as cresol and ethylphenol, alcoholic compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol and ethanol. Active methylene compounds such as methyl isobutanoyl acetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, ε-caprolactam, δ-valerolactam, etc. lactam compounds, amine compounds such as diphenylaniline, aniline and ethyleneimine, acid amide compounds such as acetanilide and acetate amide, oxime compounds such as formaldehyde, acetaldoxime, acetone oxime, methyl ethyl ketone oxime and cyclohexanone oxime, These may be used alone or in combination of two or more.

Further, the isocyanate compound in the present invention may be used alone, or may be used as a mixture or combination with various polymers. In the sense of improving the dispersibility and crosslinking properties of the isocyanate compound, it is preferable to use a mixture or combination with a polyester resin or urethane resin.

In forming the coating layer, various conventionally known polymers such as polyester resins, acrylic resins, urethane resins, etc. can be used in combination as binders in order to improve the coating appearance and transparency. In addition, particles can also be used in combination for the purpose of improving blocking properties, sliding properties, etc., within a range that does not impair the gist of the present invention.

It can be assumed that unreacted substances of various compounds in the coating liquid, compounds after reaction, or a mixture thereof are present in the coating layer of the present invention.

The proportion of wax in the total non-volatile components in the coating liquid in the present invention is usually 1% by mass or more and 40% by mass or less, preferably 10% by mass or more and 35% by mass or less. If it is less than 1% by mass, there is a concern that releasability from the mold and contamination due to oligomer components contained in the polyester film may worsen. Furthermore, if it exceeds 40% by mass, the affinity between wax and oligomer components is high, so the amount of oligomer components precipitated from the polyester film itself increases, resulting in worsening of contamination and deterioration of the appearance and strength of the coating layer. There are concerns that this may happen.

The proportion of the crosslinking agent in the total nonvolatile components in the coating solution in the present invention is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and 30% by mass or more and 50% by mass or less. More preferred. Within the above range, it is possible to achieve both coating film strength and adhesion to the polyester film.
In the present invention, from the viewpoint of suppressing the precipitation of oligomer components, coating film strength, and adhesion to the polyester film, the crosslinking agent is 20% by mass or more and 70% by mass or less of the total nonvolatile components in the coating solution. Preferably, the crosslinking agent is a melamine compound or an oxazoline compound.

When providing a coating layer by in-line coating, the procedure is to apply a coating liquid containing the above-mentioned series of compounds as an aqueous solution or dispersion with a solid content concentration of approximately 0.1 to 50% by mass on the polyester film. Preferably, the laminated polyester film is produced in a.

The thickness of the coating layer is preferably 0.002 μm or more and 1.0 μm or less, more preferably 0.005 μm or more and 0.50 μm or less, more preferably 0.01 μm or more and 0.20 μm, and particularly preferably 0.03 μm or more and 0.08 μm. It is as follows.
If the film thickness is within the above range, it is possible to suppress precipitation of oligomer components and suppress contamination due to transfer of oligomer components.
In addition, regarding the thickness of the coating layer, when an uneven structure exists on the surface of the particle-containing layer A side, the value is measured at the flat part of the recessed part.

The polyester film of the present invention may be provided with, for example, a hard coat layer, an adhesive layer, or an easily adhesive layer on the surface of the non-coated layer side, or may be provided with a coating layer on both sides of the film.
For example, when the laminated polyester film of the present invention is used as a release film for a molding process of a semiconductor package, it is preferable to provide an adhesive layer on one side of the polyester film to fix a substrate such as a lead frame. It is preferable to have a coating layer on one side and an adhesive layer on the other side.
Furthermore, in the above configuration, a configuration in which an easily bonding layer is provided between the adhesive layer and the polyester film is also preferable in order to improve the adhesion between the polyester film and the adhesive layer.
Furthermore, as described above, the polyester film has a structure in which a particle-containing layer A is provided on one side of the base layer, and a particle-containing layer B different from the particle-containing layer A is formed on the other side of the base layer. That is, since it is preferable to have a structure including the particle-containing layer A, the base material layer, and the particle-containing layer B in this order, for example, when the laminated polyester film of the present invention is used as a release film for a molding process of a semiconductor package, a preferable structure is as follows. Examples include coating layer/particle-containing layer A/substrate layer/particle-containing layer B/adhesive layer, and coating layer/particle-containing layer A/substrate layer/particle-containing layer B/adhesive layer/adhesive layer.

The adhesive layer is provided for fixing a substrate such as a lead frame in, for example, a semiconductor package molding process. In addition, after the purpose of the film is achieved, the adhesive layer is removed at the same time as the release film for the process, so the adhesive layer can be peeled off from the substrate such as the lead frame, and there will be no adhesive residue after peeling. It is preferable that there is no surface staining property.

The adhesive layer contains an adhesive composition. The adhesive composition can be used without particular limitation as long as it can impart tackiness, and examples include acrylic adhesives, urethane adhesives, rubber adhesives, and silicone adhesives. Among these, acrylic pressure-sensitive adhesives are preferred from the viewpoint of easy adjustment of adhesive properties and excellent transparency. Further, examples of methods for forming the adhesive include a thermosetting type, an active energy ray curing type, and a hot melt type.

A method for forming the adhesive layer is, for example, by dissolving or dispersing the adhesive substance or its composition in a solvent consisting of an appropriate solvent such as toluene or ethyl acetate, alone or in a mixture, to form an adhesive solution of about 10 to 40% by weight. method, apply it on a protective film, heat and dry it to form an adhesive layer, and then laminate the separator.Alternatively, apply it on a separator, heat and dry it to form an adhesive layer, and then apply the protective film. There are ways to match them.

A known method is used to apply the adhesive liquid. Specifically, the method mentioned above can be mentioned as a method for applying the coating layer.

The thickness of the adhesive layer is preferably in the range of 1 to 500 μm, more preferably 5 to 200 μm, and still more preferably 10 to 100 μm. Within the above range, sufficient adhesive strength may be obtained and peeling may become easy.

The easily adhesive layer is a layer that improves the adhesion between the surface of the polyester film and other layers.

The easily adhesive layer can be provided by various conventionally known methods such as coating, transfer, lamination, etc. Among these, providing by coating is preferable from the viewpoint of ease of manufacturing. It may be provided by in-line coating or by off-line coating, but from the viewpoint of manufacturing cost and improving the strength of the adhesive layer layer and the adhesion with the film due to heat treatment during the film manufacturing process, in-line coating is preferable. Preferably used.

The resin contained in the easy-adhesion layer may be a conventionally known resin, such as polyester resin, acrylic resin, urethane resin, and polyvinyl resin (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.). Among these, polyester resin, acrylic resin, and urethane resin are preferred from the viewpoint of adhesion to the polyester film, and acrylic resin is particularly preferred from the viewpoint of adhesion to the adhesive layer.

Further, in order to increase the strength of the easily adhesive layer, it is preferable to use a crosslinking agent in combination. As the crosslinking agent, various known crosslinking agents can be used, such as oxazoline compounds, melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds.
Among them, from the viewpoint of adhesion, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds, especially oxazoline compounds and isocyanate compounds, are more preferable, and from the viewpoint of increasing the strength of the easy-adhesion layer, melamine compounds are preferable. is preferred.

When forming an easily adhesive layer by coating, the coating solution may contain, in addition to the above resins, other binders, surfactants, particles, antifoaming agents, coating improvers, thickeners, and antioxidants. , an ultraviolet absorber, a blowing agent, a dye, a pigment, etc.
Furthermore, the surface of the polyester film may be subjected to chemical treatment, corona discharge treatment, plasma treatment, etc. before coating.

The thickness of the easily adhesive layer is preferably in the range of 0.001 to 1 μm, more preferably 0.01 to 0.5 μm, and even more preferably 0.02 to 0.2 μm. By using the thickness of the easily bonding layer within the above range, the adhesiveness with other layers will be good.

The average surface roughness (Ra) of the coating layer side surface of the laminated polyester film of the present invention is preferably 0.2 μm or more, more preferably 0.3 μm or more. Although the upper limit is not particularly limited, it is usually 3.0 μm or less.
Since the average surface roughness (Ra) of the coating layer side surface is 0.2 μm or more, when the laminated polyester film of the present invention is used as a release film for a semiconductor molding process, it has good releasability from a mold. can be improved.
Examples of methods for making the average surface roughness (Ra) of the coating layer side surface 0.2 μm or more include adding particles to the coating layer or using a polyester film provided with the above-mentioned particle-containing layer A. .

The average surface roughness (Ra) of the non-coated layer side surface of the laminated polyester film of the present invention is the average surface roughness (Ra) of the coated layer side surface from the viewpoint of making it easier to laminate a desired layer on the surface. Ra), and specifically, the average surface roughness (Ra) is preferably less than 0.20 μm. On the other hand, the lower limit is preferably 0.020 μm or more, more preferably 0.025 μm or more, from the viewpoint of film processability, slipperiness, and anti-blocking prevention.

In the laminated polyester film of the present invention, the change in film haze (ΔH) before and after heat treatment (150°C, 90 minutes) is preferably 1.5% or less, more preferably 1.0% or less, and 0. More preferably, it is .5% or less. It is known that polyester films have increased film haze due to the precipitation of oligomer components on the film surface due to heat treatment, and ΔH is an index indicating the precipitation of oligomer components on the film surface before and after heat treatment.
When the amount of change in film haze (ΔH) is 1.5% or less, there is a possibility that contamination due to precipitation of oligomer components can be suppressed.

As a method for providing the coating layer, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc. can be used.

There are no particular limitations on the drying and curing conditions when forming a coating layer on a polyester film. For example, when forming a coating layer by offline coating, it is usually recommended to perform heat treatment at 80 to 200°C for 3 to 40 seconds, preferably at 100 to 180°C for 3 to 40 seconds.

On the other hand, when providing a coating layer by in-line coating, it is usually preferable to perform heat treatment at 70 to 280° C. for 3 to 200 seconds.

Furthermore, irrespective of offline coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet ray irradiation may be used in combination as necessary. The polyester film constituting the laminated polyester film of the present invention may be previously subjected to surface treatment such as corona treatment or plasma treatment.

The various components in the coating layer can be analyzed by, for example, TOF-SIMS, ESCA, fluorescent X-ray analysis, or the like.

The laminated polyester film of the present invention can be used as a protective film or a release film for various processing steps, and among others, it can be suitably used as a release film for semiconductor molding steps.
An example of a method for manufacturing a semiconductor package will be described.
First, a plurality of semiconductor chips arranged on a lead frame are inserted into respective semiconductor package molding spaces of one mold A, and then a release film and the other mold B are sequentially positioned.
Next, molds A and B are clamped at a predetermined pressure so that the release film is tightly attached to the lead frame surface, and then molten mold resin is filled into each semiconductor package molding space and hardened for a predetermined time. In this manner, one semiconductor package is molded for each semiconductor package molding space.
Next, when mold A and mold B are removed from the semiconductor package, the semiconductor package is formed on the lead frame. The lead frame is then cut into individual semiconductor packages.
The used mold release film is removed when the molds A and B are removed from the semiconductor package, and is supplied for each molding cycle.
The laminated polyester film of the present invention suppresses contamination due to oligomer components precipitated from the polyester film. When used as a release film for the molding process of semiconductor packages, which is placed between a lead frame and a mold and is used in a semiconductor package manufacturing method in which the mold is filled with mold resin, it prevents contamination of the mold by oligomer components. Since it can be prevented, it can be suitably used for this purpose.
However, the laminated polyester film of the present invention is not limited to the above-mentioned uses, and can also be suitably used, for example, as a transfer film that can transfer a matte appearance, or as a mold-forming film for insert molding, in-mold molding, etc.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof. Moreover, the measurement method and evaluation method used in the present invention are as follows.

(1) Intrinsic viscosity of polyester Accurately weigh 1 g of polyester from which incompatible components have been removed, add 100 ml of a mixed solvent of phenol/tetrachloroethane = 50/50 (weight ratio) to dissolve it, and measure at 30°C. did.

(2) Average particle size of particles The equivalent sphericity distribution of particles made of powder was measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3 type) manufactured by Shimadzu Corporation, and the cumulative volume fraction of each particle size range was calculated. The particle size at a cumulative volume fraction of 50% in the equivalent sphericity distribution in which the particles were measured was taken as the average particle size.

(3) Average surface roughness (Ra)
It was determined as follows using a surface roughness measuring machine (SE-3500) manufactured by Kosaka Institute Co., Ltd. That is, a portion of reference length L (2.5 mm) is extracted from the film cross-sectional curve in the direction of its average line, and the roughness curve is created with the average line of this extracted portion as the x axis and the direction of vertical magnification as the y axis. When expressed as (x), the value given by the following formula is expressed as [nm]. The average surface roughness was determined by determining 10 roughness curves from the surface of the sample film, and was expressed as the average value of the average surface roughness of the sampled portions determined from these roughness curves. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.
Ra=(1/L)∫L0|f(x)|dx

(4) Thickness of coating layer The surface of the coating layer was dyed with RuO ₄ and embedded in epoxy resin. Thereafter, the section prepared by the ultrathin section method was stained with RuO ₄ , and the cross section of the coated layer was measured using a transmission electron microscope (TEM) (manufactured by Hitachi High-Technologies Corporation, H-7650, acceleration voltage 100 kV).

(5) Softening point of wax The softening point of wax was measured in accordance with JIS-K2207.

(6) Heat treatment of film The laminated polyester film obtained in each Example and Comparative Example was stacked with Kent paper and fixed with the coated layer side surface exposed for 90 minutes at 150°C under a nitrogen atmosphere. It was left to stand for heat treatment. However, in Comparative Example 6, since no coating layer was provided, the Kent paper was stacked with the surface of the particle-containing layer A side of the polyester film exposed.

(7) Film Haze The film haze of each sample film was measured in accordance with JIS-K-7136 using a haze meter (HM-150) manufactured by Murakami Color Research Laboratory Co., Ltd.

(8) Change in film haze due to heat treatment 80 parts by mass of dipentaerythritol hexaacrylate, 2- After drying a mixed coating liquid consisting of 20 parts by mass of hydroxy-3-phenoxypropyl acrylate, 5 parts by mass of a photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.), and 200 parts by mass of methyl ethyl ketone, the thickness was It was coated to a thickness of 3 μm, dried, and cured by irradiating ultraviolet rays to form a hard coat layer. In Comparative Example 6, a coating layer was not provided on the polyester film, but a hard coat layer was formed on the surface of the polyester film on the particle-containing layer B side. The film haze of the laminated polyester film having a hard coat layer was measured from the non-hard coat layer side using the method (7). Next, after heating by method (6), the film haze after heat treatment was measured by method (7). The difference between the haze after heat treatment and the film haze before heat treatment was calculated and used as the amount of change in film haze. The lower the amount of change in film haze is, the better it is because it indicates that the oligomer component (ester cyclic trimer component) is less precipitated by heat treatment.

(9) Transfer of oligomer components A laminated polyester film and a stainless steel plate (product name: HS0543) with a thickness of 0.5 mm were cut into 10 cm x 5 cm pieces, the surface of the particle-containing layer A side of the film and the stainless steel plate were overlapped, and a heat press was applied. A sample was prepared by pressing at 180° C. and a pressure of 20 MPa for 5 minutes.
Immediately after creating the sample, the laminate of the film and stainless steel plate was placed horizontally with the film facing upwards, then the film was lifted vertically and peeled off, and the surface of the stainless steel plate on the film side was observed. The area ratio of contamination (transferred substances of oligomer components) to the area of the film side surface was evaluated. 〇 (very good) if no contamination can be confirmed, △ (good) if the area ratio of the contaminated area is less than 5% of the stainless steel plate and there is no practical problem, and △ (good) if the area ratio of the contaminated area is less than 5% of the stainless steel plate, and contamination is noticeable if it exceeds 5%. , Those that have practical problems are marked as bad.

The following composition was used for the polyester film.
Polyester (I): A polyester resin composition consisting of polyethylene terephthalate (intrinsic viscosity: 0.63 dl/g).
Polyester (II): A polyethylene terephthalate composition containing 10% by mass of alkyl methacrylate-styrene copolymer particles with an average particle size of 4.5 μm (intrinsic viscosity: 0.61 dl/g).
Polyester (III): A polyethylene terephthalate composition containing 0.7% by mass of silica particles with an average particle size of 2.7 μm (intrinsic viscosity: 0.61 dl/g).
A polyethylene terephthalate composition (intrinsic viscosity: 0.62 dl/g) containing 0.3% by mass of polyester (IV) silica particles having an average particle size of 2.0 μm.

The following composition was used for the coating liquid.
Wax 1 (W1): Oxidized polyethylene wax with a softening point of 130°C.
Wax 2 (W2): Polyethylene wax with a softening point of 138°C Wax 3 (W3): Polyethylene wax with a softening point of 110°C Wax 4 (W4): Polyethylene wax with a softening point of 60°C Wax 5 (W5): Polyethylene wax with a softening point of 65°C Paraffin wax Wax 6 (W6): Carnauba wax with a softening point of 85°C

Melamine compound (C1): hexamethoxymethylolmelamine

Oxazoline compound (C2): Acrylic polymer with oxazoline group and polyalkylene oxide chain Product name: "Epocross" (oxazoline group weight = 7.7 mmol/g, manufactured by Nippon Shokubai Co., Ltd.)

Epoxy compound (C3): Water-soluble polyglycerol polyglycidyl ether

Polyester resin (B1): 42 parts by mass of polyester resin formed from (acid component) isophthalic acid//(diol component) diethylene glycol/neopentyl glycol = 100//70/30 (mol%) and 58 parts by mass of polymethyl methacrylate. An aqueous dispersion of acrylic modified polyester resin formed from

[Example 1]
A mixture of polyesters (I) and (II) at a ratio of 50% by mass and 50% by mass, respectively, was used as the raw material for the particle-containing layer A, and polyester (I) was used as the raw material for the base layer. A mixed raw material prepared by mixing III) at a ratio of 70% by mass and 30% by mass, respectively, was used as the raw material for particle-containing layer B, and each was supplied to three extruders, melted at 285 ° C., and then set at 40 ° C. An unstretched sheet was obtained by coextrusion with a layer configuration of 3 types and 3 layers (discharge rate of particle-containing layer A/base material layer/particle-containing layer B = 5:30:3) on a cooling roll, which was then cooled and solidified. . Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85° C. using the difference in peripheral speed of the rolls, and then coating liquid 1 shown in Table 1 below was applied to the surface of the particle-containing layer A of this longitudinally stretched film. After being guided into a tenter and stretched 4.0 times in the transverse direction at 110°C and heat treated at 225°C, the film was relaxed by 2% in the transverse direction, and the thickness of the coating layer (after drying) was 0.05 μm. A laminated polyester film having a diameter of 38 μm (particle-containing layer A/substrate layer/particle-containing layer B=5 μm/30 μm/3 μm) was obtained.
The average surface roughness (Ra) of the particle-containing layer A side surface of the obtained laminated polyester film was 0.33 μm, and the average surface roughness (Ra) of the particle-containing layer B side surface was 0.025 μm. The increase in film haze (ΔH) was 0.2%, and the area ratio of contaminated areas due to transfer of oligomer components was 5% or less relative to the stainless steel plate, which was a good result. The properties of this film are shown in Table 2 below.

[Examples 2 to 10]
A laminated polyester film was obtained in the same manner as in Example 1 except that the composition of the coating liquid was changed to the composition shown in Table 1. As shown in Table 2, the obtained laminated polyester film had good results in film haze increase (ΔH) and transfer of oligomer components due to heat treatment.

[Example 11]
A mixture of polyester (I) and (IV) at a ratio of 94% by mass and 6% by mass, respectively, was used as the raw material for particle-containing layer A, and polyester (I) was used as the raw material for the base layer, and the mixture was put into two extruders. After each is supplied and melted at 285°C, two types of three layers (discharge rate of particle-containing layer A/base material layer/particle-containing layer A = 4:30:4) are placed on a cooling roll set at 40°C. ) was coextruded, cooled, and solidified to obtain an unstretched sheet. Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85° C. using the difference in peripheral speed of the rolls, and coating solution 3 shown in Table 1 below was applied to one side of the longitudinally stretched film, and then introduced into a tenter and stretched horizontally. After stretching 4.0 times in the direction at 110°C and heat-treating at 225°C, it was relaxed by 2% in the transverse direction, and the thickness of the coated layer (after drying) was 0.05 μm (38 μm (containing particles)). A laminated polyester film having layer A/base layer/particle-containing layer A=4 μm/30 μm/4 μm was obtained.
The average surface roughness (Ra) of the particle-containing layer A side surface of the obtained laminated polyester film was 0.010 μm, and as shown in Table 2, the obtained laminated polyester film showed an increase in film haze (ΔH) due to heat treatment. , and the results of transfer of oligomer components were good.

[Comparative Examples 1 to 5]
A laminated polyester film was obtained in the same manner as in Example 1 except that the composition of the coating liquid was changed to the composition shown in Table 1. As shown in Table 2, in the obtained laminated polyester film, the area ratio of contaminated parts due to transfer of oligomer components exceeded 5% of the stainless steel plate.

[Comparative example 6]
A polyester film was obtained in the same manner as in Example 1 except that no coating layer was provided.
As shown in Table 2, the resulting polyester film had a film haze increase (ΔH) of 1.8% due to heat treatment, and the area ratio of the contaminated portion exceeded 5% compared to the stainless steel plate.

From the results of the above Examples and Comparative Examples and the test results conducted by the present inventors, it has been found that a wax with a softening point of 90°C or higher is used, and the proportion of wax in the total non-volatile components is 1% by mass or more and 40% by mass. It has been found that a laminated polyester film including a coating layer formed from the following coating liquid can suppress the transfer of oligomer components.

The laminated polyester film of the present invention is excellent in preventing contamination during processing steps, and can be suitably used, for example, as a film for process protection or a release film for semiconductor package molding steps.

Claims (9)

A coating layer is provided on the surface of the polyester film, and the coating layer is formed from a coating liquid containing wax, and the content of the wax is 1% by mass or more and 40% by mass as a proportion of the total nonvolatile components in the coating liquid. A laminated polyester film having the following properties and wherein the softening point of the wax is 90°C or higher,
A laminated polyester film, which has an average surface roughness (Ra) of the coating layer side surface of 0.2 μm or more, and is used as a film for a semiconductor molding process. The laminated polyester film according to claim 1, wherein the coating liquid contains a crosslinking agent. The laminated polyester film according to claim 2, wherein the content of the crosslinking agent is 20% by mass or more and 70% by mass or less as a proportion of the total nonvolatile components in the coating liquid. The laminated polyester film according to claim 2 or 3, wherein the crosslinking agent is at least one selected from melamine compounds, oxazoline compounds, and epoxy compounds. The laminated polyester film according to any one of claims 1 to 4, wherein the coating layer has a thickness of 0.002 μm or more and 1.0 μm or less. 80 parts by mass of dipentaerythritol hexaacrylate, 20 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate, and a photopolymerization initiator (trade name) were added to the surface of the laminated polyester film opposite to the surface on which the coating layer was provided. A mixed coating solution consisting of 5 parts by mass of Irgacure 184 (manufactured by Ciba Specialty Chemicals Co., Ltd.) and 200 parts by mass of methyl ethyl ketone was applied to a dry thickness of 3 μm, dried, and cured by irradiation with ultraviolet rays. A hard coat layer is formed to prepare a sample film.
The laminated polyester film according to any one of claims 1 to 5, wherein the sample film has a change in film haze on the coating layer side of 1.5% or less before and after heat treatment at 150° C. for 90 minutes in a nitrogen atmosphere. The laminated polyester according to any one of claims 1 to 6, wherein the polyester film comprises a particle-containing layer A, a base layer, and a particle-containing layer B in this order, and the coating layer is provided on the surface of the particle-containing layer A side of the polyester film. film. 8. The ratio of the thickness of the base layer to the thickness of the polyester film ((thickness of base layer)/(thickness of polyester film)) is 0.60 or more and 0.99 or less. laminated polyester film. Using the laminated polyester film according to any one of claims 1 to 8 as a release film,
After inserting the semiconductor chip placed on the lead frame into the semiconductor package molding space of one mold A, sequentially positioning the release film and the other mold B,
Next, after clamping the molds A and B so that the release film is brought into close contact with the surface of the lead frame, molten mold resin is filled into the semiconductor package molding space and cured. Features: A method for manufacturing semiconductor packages.