JP7423913B2 - laminated polyester film - Google Patents

Description

The present invention relates to a laminated polyester film having a matte appearance and having a coating layer on the surface thereof.

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 the molding process of semiconductor packages, in addition to the above properties, properties other than those listed above are also required. In some cases, it is required to improve the releasability of the polyester film and to suppress the precipitation of low molecular weight components (oligomer components) contained in the polyester film.

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.

Further, Patent Document 2 discloses a release sheet including a concavo-convex layer formed on one side of a base material using a coating agent containing fine particles and a curable resin.

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 during the semiconductor package molding process, there is a concern that the releasability may not be sufficient depending on the process conditions.
In the mold release sheet described in Patent Document 2, during the semiconductor package molding process, fine particles fall off from the uneven layer and contaminate the mold, or the contamination progresses and the flatness of the mold is lost, resulting in sealing failure. There is a concern that it may cause resin leakage.

JP2017-179334A Japanese Patent Application Publication No. 2014-212239

The present invention has been made in view of the above circumstances, and the problem to be solved is, for example, regarding a laminated polyester film used in the molding process of semiconductor packages, a laminated polyester film that is suppressed from contamination by oligomer components and has excellent peelability. Our goal is to provide the following.

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. .

That is, the gist of the present invention is that a coating layer is provided on one surface of a polyester film provided with a particle-containing layer A, the coating layer is a layer formed from a coating liquid containing a melamine compound, and the coating layer is a layer formed from a coating liquid containing a melamine compound. A laminated polyester film characterized by having an average surface roughness (Ra) of 0.30 μm or more.

According to the present invention, it is possible to provide a laminated polyester film that suppresses mold contamination by oligomer components and has excellent releasability when used as a release film for a semiconductor package molding process, for example.

Hereinafter, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below, and can be implemented with arbitrary modifications within the scope of the gist of the present invention.

The polyester film constituting the laminated polyester film of the present invention includes a particle-containing layer A.
The structure of the polyester film may include only the particle-containing layer A, or may include the particle-containing layer A on one or both sides of the base layer. 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. Since a configuration including A, a base material layer, and a particle-containing layer B in this order is preferable, this configuration will be described in detail later.
The polyester film may be a non-stretched film (sheet) or a stretched film. Among these, a stretched film stretched uniaxially or biaxially is preferred. Among these, biaxially stretched films are preferred because they are excellent in balance of mechanical properties and flatness.

The layers constituting the polyester film, such as the particle-containing layer A, the base layer, the particle-containing layer B, and other layers, 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.

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, oxycarboxylic acid, etc. 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 or 30 mol% or less, especially 25 mol% or less, especially 7 mol% or more or 22 mol%. % or less is more preferable. 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.As the amount of metal remaining in the film is small, there are fewer defects in the film due to metal aggregation, and the film can be improved. This is preferable because it increases the brightness.

The particle-containing layer A constituting the polyester film in the present invention is a layer containing particles in the layer. Since the surface of the polyester film including the particle-containing layer A is roughened, it has excellent releasability from a mold, for example.

It is preferable that the particle-containing layer A contains particles having an average particle diameter of 2.0 μm or more. By containing particles having an average particle size of 2.0 μm or more in the particle-containing layer A, the surface of the polyester film can be roughened, giving it a matte appearance, and, for example, preventing the formation of particles from a mold. Removability can be improved. However, if the average particle size of the particles is too large, the pressure increase in the filter during the polyester extrusion process during film production may increase, leading to a decrease in productivity. Therefore, the average particle size of the particles is preferably 2.0 μm or more, especially 10.0 μm or less, especially 3.0 μm or more or 9.0 μm or less, and especially 4.0 μm or more or 8.0 μm or less. is even more preferable.

In addition, when the particles are powder, the average particle diameter of the particles is the equivalent spherical shape measured using a centrifugal sedimentation type particle size distribution analyzer (for example, SA-CP3 model manufactured by Shimadzu Corporation). The particle size (d50) at an integrated volume fraction of 50% in the distribution 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.

In addition, in the particle-containing layer A, when particles with an average particle size of 2.0 μm or more and particles with different average particle sizes are mixed, and both particles are made of the same material, separate particles with different average particle sizes are used as raw materials. However, when mixed (compounded), it becomes nothing but one type of particle with an average particle size between these two. In such a case, it shall be determined whether particles having an average particle size of 2.0 μm or more are contained based on the average particle size after mixing.

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 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 oxide, 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 a single or copolymer of vinyl monomers such as acrylic acid or methacrylic acid. Other organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenolic resin may also be used.

The content of particles in the particle-containing layer A is 0.1 to 20 mass from the viewpoint of suitably roughening the surface of the polyester film and preventing breakage etc. during film stretching. %, particularly preferably 1% by mass or more and 18% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 10% by mass or less.

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

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 include a layer containing particles, or may consist only of a layer containing particles. However, from the viewpoint of cost, it is preferable that the layer does not contain particles such as the above-mentioned organic particles and inorganic particles.

The thickness of the base material layer is determined by the ratio of the thickness of the base material layer to the thickness of the polyester film ((thickness of the base material layer)/(thickness of the polyester film) from the viewpoint of preventing curling of the laminated polyester film. )) is preferably 0.60 to 0.99, especially 0.65 or more or 0.99 or less, and even more preferably 0.70 or more and 0.99 or less. By falling within this range, the base material layer itself becomes stiff, making it difficult for the laminated polyester film to curl.

As described above, the particle-containing layer A can be provided on one side of the base layer, and the particle-containing layer B, which is different from the particle-containing layer A, can be formed on the other side of the base layer.

Particle-containing layer B is a layer containing particles in the layer, and like particle-containing layer A, it should contain particles with an average particle size of 2.0 μm or more in order to prevent curling of the laminated polyester film. is preferred.
However, since the surface of the particle-containing layer B side of the laminated polyester film does not need to be as rough as the surface of the particle-containing layer A side, it is important to note that the particle-containing layer A and the particle-containing layer B contain particles with an average particle size of 2.0 μm or more. When contained, the content of particles having an average particle diameter of 2.0 μm or more may be smaller than that in the particle-containing layer A. Since the content of particles with an average particle size of 2.0 μm or more is smaller in the particle-containing layer B than in the particle-containing layer A, curling of the entire laminated polyester film can be prevented, while the surface of the particle-containing layer A side is While roughening the surface, it is possible to easily laminate a desired layer on the surface of the particle-containing layer B side. For example, when using a laminated polyester film as a release film for the molding process of semiconductor packages, it is necessary to provide an adhesive layer or the like on the surface of the particle-containing layer B side for fixing a substrate such as a lead frame. This is a suitable configuration.
The content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in particle-containing layer B is 0% of the content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in particle-containing layer A. .1 to 100%, especially 1% or more or 95% or less, more preferably 5% or more or 90% or less, 10% or more or 80% or less, and 60% It is more preferable that it is as follows.

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

The content of particles in the particle-containing layer B is 0.05 to 10% by mass, since it can prevent the entire polyester film from curling while making it easier to laminate a desired layer on the surface of the particle-containing layer B. The content is preferably 0.1% by mass to 18% by mass, and more preferably 0.1% by mass to 18% by mass.

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

Each layer constituting the polyester film of the present invention may contain conventionally known weathering agents, light stabilizers, light shielding agents, antioxidants, heat stabilizers, lubricants, antistatic agents, optical brighteners, dyes, Pigments etc. can be added.

Further, in order to improve the weather resistance of the film and prevent deterioration of the liquid crystal, etc., it is also possible to contain an ultraviolet absorber in each layer. 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 iminoesters, 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 for adding particles to each layer constituting the polyester film in the present invention 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 before the start of the polymerization reaction of the polyester.

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.

Production examples of the laminated polyester film of the present invention will be specifically described, but the production examples are not limited to the following production examples. For example, when producing a biaxially stretched polyester film, first, pellets of the above-mentioned dried polyester raw material are extruded as a molten sheet from a die using an extruder, and then cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the rotating cooling drum, and an electrostatic application adhesion method and/or a liquid application adhesion method are preferably employed. The resulting unstretched sheet is then biaxially stretched. In that case, first, the unstretched sheet is stretched in one direction using 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, it is stretched in a direction perpendicular to the first stage stretching direction, and in that case, 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. be. Subsequently, heat treatment is performed at a temperature of 180 to 270° C. under tension or under relaxation of 30% or less to obtain a biaxially oriented film. In the above-mentioned stretching, a method of stretching in one direction in two or more stages can also be adopted. In that case, it is preferable to carry out the stretching so that the final stretching ratios in both directions fall within the above ranges.

Moreover, a simultaneous biaxial stretching method can also be employed for producing the polyester film constituting the laminated polyester film of the present invention. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is stretched and oriented simultaneously in the machine direction and the width direction under temperature control, usually at 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is The area magnification is 4 to 50 times, preferably 7 to 35 times, more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250° C. under tension or relaxation within 30% to obtain a stretched oriented film. Regarding the simultaneous biaxial stretching apparatus that employs the above-mentioned stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

Next, the formation of the coating layer constituting the laminated polyester film of the present invention will be explained. Examples of methods for forming the coating layer include methods such as coating, transfer, and lamination, but in consideration of ease of forming the coating layer, it is preferable to form the coating layer.

Coating methods for forming the coating layer include, for example, gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, Conventionally known coating methods such as kiss coating, spray coating, calendar coating, extrusion coating, etc. can be used.

As for the coating method, it may be provided by in-line coating performed within the film manufacturing process, or it may be provided by off-line coating, which is performed by coating the film once manufactured outside the system. More preferably, it is formed by in-line coating.

Specifically, in-line coating is a method in which coating is performed at any stage from melt-extruding the resin forming the film to stretching, heat-setting, and winding. Usually, the coating is applied to an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after heat set before winding up. 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 production and coating layer formation can be performed at the same time, which has an advantage in terms of production costs.Also, since stretching is performed after coating, the thickness of the coating layer can be changed by the stretching ratio. , compared to offline coating, thin film coating can be performed more easily.

In addition, according to the in-line coating process, the thickness of the film does not change significantly depending on whether a coating layer is formed, and the risk of scratches or foreign matter adhesion does not change significantly depending on whether a coating layer is formed. This is a major advantage compared to off-line coating, which is performed separately.

Further, by providing a coating layer on the film before stretching, the coating layer can be stretched together with the film, thereby making it possible to firmly adhere the coating layer to the film.

Furthermore, in the production of biaxially stretched polyester film, by holding the edges of the film with clips and stretching it, the film can be restrained in both the vertical and horizontal directions, and no wrinkles will form during the heat setting process. High temperatures can be applied to the surface while maintaining its smoothness.
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 film can be bonded more firmly. can form a strong coating layer.
Furthermore, as described above, there is an advantage that the heat resistance of the film can be improved by stretching the film while holding its edges and forming a coating layer through a heat setting process. This is thought to be due to the fact that heat treatment can be performed at a high temperature that cannot be obtained with offline coating, and the coating layer is formed to be able to withstand even higher temperatures.

The temperature of the heat treatment of the coating layer provided by in-line coating is preferably 55 to 300°C, more preferably 70 to 290°C, even more preferably 90 to 280°C, particularly preferably 170 to 270°C, and most preferably 200°C to The temperature is 250°C. As a guideline, it is best to perform heat treatment for 3 to 200 seconds.

When a coating layer is provided by off-line coating, heat treatment is usually carried out at 80 to 200°C for 3 to 40 seconds, preferably at 100 to 180°C for 3 to 40 seconds.

Regarding the formation of the coating layer, a series of compounds described below are used as a solution or a dispersion of a solvent, and a coating liquid whose solid content concentration is adjusted to approximately 0.1 to 50% by mass is laminated by applying it on the polyester film. Preferably, polyester films are produced.
When forming a coating layer by in-line coating, the coating liquid is preferably an aqueous solution or an aqueous dispersion, but a small amount of an organic solvent may be added to the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, etc. May contain. Furthermore, only one type of organic solvent may be used, or two or more types may be used as appropriate.

Further, heat treatment and active energy ray irradiation such as ultraviolet ray irradiation may be used in combination as necessary. The surface of the polyester film constituting the laminated polyester film of the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance before providing the coating layer.

Next, the coating layer provided on one surface of the polyester film in the present invention will be described. The coating layer is a layer formed from a coating liquid containing a melamine compound. Note that the coating layer may contain other components.

In the present invention, it has been found that by providing a coating layer formed from a coating liquid containing a melamine compound on the surface of a polyester film, it is possible to suppress the precipitation of oligomer components and have excellent releasability. Although the reason for this is not clear, it is thought that the melamine compound in the coating layer forms a crosslinked structure to form a dense film, which suppresses the precipitation of oligomer components in the polyester film. It is also believed that the melamine compound in the coating layer forms a crosslinked structure, which improves the heat resistance of the coating layer itself.
As a result, when the laminated polyester film of the present invention is pressure-bonded to a mold while heating, a coating layer that suppresses the precipitation of oligomer components and has excellent heat resistance exists between the polyester film and the mold. It is thought that it is possible to prevent contamination of the mold by oligomer components and maintain releasability from the mold.
Furthermore, it is also possible to prevent particles from falling off from the polyester film by providing a coating layer on the surface of the polyester film.
Note that the oligomer component in the present invention is a low molecular weight component of polyester that precipitates on the surface of a polyester film by heating, and refers to an ester cyclic trimer.

Melamine compounds are compounds that have a melamine skeleton in the compound, and include, for example, 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.

For the material of the coating layer other than melamine compounds, from the viewpoint of suppressing the precipitation of oligomer components on the surface of the polyester film, compounds with a chemical structure different from that of the polyester resin or compounds that can be crosslinked are effective. For example, long-chain alkyl compounds , a compound having an ammonium group, polyvinyl alcohol, and the like. Among these, long-chain alkyl compounds are preferred from the viewpoint of improving handling properties such as peelability.

A long-chain alkyl compound is a compound having a linear or branched alkyl group having usually 6 or more carbon atoms, preferably 8 or more carbon atoms, and more preferably 12 or more carbon atoms. Examples of the alkyl group include hexyl group, octyl group, decyl group, lauryl group, octadecyl group, and behenyl group.
Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. In consideration of heat resistance and stain resistance, a polymer compound is preferable. Further, from the viewpoint of effectively obtaining mold release properties, a polymer compound having a long-chain alkyl group in its side chain is more preferable.

A polymer compound having a long-chain alkyl group in its side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the above-mentioned reactive group include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride, and the like.
Examples of compounds having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, reactive group-containing polyester resin, and reactive group-containing poly(meth)acrylic resin. Among these, polyvinyl alcohol is preferred in consideration of mold releasability and ease of handling.

Compounds having an alkyl group that can react with the above-mentioned reactive groups include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, behenyl isocyanate, hexyl chloride, octyl chloride, Examples include long-chain alkyl group-containing acid chlorides such as decyl chloride, lauryl chloride, octadecyl chloride, and behenyl chloride, long-chain alkyl group-containing amines, and long-chain alkyl group-containing alcohols. Among these, long-chain alkyl group-containing isocyanates are preferred in consideration of mold releasability and ease of handling, and octadecyl isocyanate is particularly preferred.

Additionally, polymer compounds having long-chain alkyl groups in their side chains can also be obtained by polymerizing long-chain alkyl (meth)acrylates or copolymerizing long-chain alkyl (meth)acrylates with other vinyl group-containing monomers. . Examples of long-chain alkyl (meth)acrylates include hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and behenyl (meth)acrylate. It will be done.

The ammonium group-containing compound is a compound having an ammonium group in the molecule, and includes ammonium compounds of aliphatic amines, alicyclic amines, and aromatic amines. The compound having an ammonium group is preferably a polymer-type compound having an ammonium group, and the ammonium group has a structure in which it is incorporated into the main chain or side chain of the polymer, rather than as a counter ion. It is preferable. For example, a polymer compound having an ammonium group made from a polymer obtained by polymerizing a monomer containing an addition-polymerizable ammonium group or a precursor of an ammonium group such as an amine can be mentioned and preferably used. The polymer may be a monomer containing an addition-polymerizable ammonium group or a precursor of an ammonium group such as an amine, or a copolymer of a monomer containing these and another monomer. It's okay.

Among the ammonium group-containing compounds, pyrrolidinium ring-containing compounds are preferred because they suppress the amount of ester cyclic trimer precipitated by heating and are excellent in heat resistance stability.

The two substituents bonded to the nitrogen atom of the compound having a pyrrolidinium ring are each independently an alkyl group, a phenyl group, etc., and even if these alkyl groups or phenyl groups are substituted with the groups shown below, good. Substitutable groups include, for example, a hydroxyl group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, and a halogen. Furthermore, the two substituents bonded to the nitrogen atom may be chemically bonded, for example, -(CH ₂ ) _m - (m=an integer of 2 to 5), -CH(CH ₃ )CH (CH ₃ )-, -CH=CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, -CH ₂ OCH ₂ -, -(CH ₂ ) ₂ O (CH ₂ ) ₂ - and the like.

A polymer having a pyrrolidinium ring can be obtained by cyclization polymerizing a diallylamine derivative using a radical polymerization catalyst. Polymerization is carried out using a known polymerization initiator such as hydrogen peroxide, benzoyl peroxide, or tertiary butyl peroxide in a polar solvent such as water or methanol, ethanol, isopropanol, formamide, dimethylformamide, dioxane, or acetonitrile as a solvent. The method can be implemented by, but is not limited to, these methods. A compound having a carbon-carbon unsaturated bond that is polymerizable with the diallylamine derivative may be used as a copolymerization component. From the viewpoint of suppressing the amount of ester cyclic trimer precipitated by heating, copolymers with various compounds having carbon-carbon unsaturated bonds (acrylic and methacrylic compounds) are preferable to homopolymers of diallylamine derivatives. is preferable.

In addition, a polymer having the structure of the following formula (1) is also preferable in that it is excellent in suppressing precipitation of oligomer components and having excellent humidity and heat resistance stability. It may be a single polymer, a copolymer, or a copolymer of a plurality of other components. From the viewpoint of being able to reduce the amount of ester cyclic trimer precipitated by heating, a compound having the structure of the following formula (1) is preferable to the above-mentioned compound having a pyrrolidinium ring.

For example, in the above formula, substituent R ¹ is a hydrogen atom or a hydrocarbon group such as an alkyl group having 1 to 20 carbon atoms or a phenyl group, R ² is -O-, -NH- or -S-, and R ³ is An alkylene group having 1 to 20 carbon atoms or other structure that can form the structure of formula 1, R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group. or a hydrocarbon group provided with a functional group such as a hydroxyalkyl group, and X ⁻ is various counter ions.

Among the above, in formula (1), the substituent R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, particularly from the viewpoint of excellent antistatic properties and moist heat resistance stability; ³ is preferably an alkyl group having 1 to 6 carbon atoms, R ⁴ , R ⁵ , and R ⁶ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably , a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Examples of the anion serving as a counter ion to the ammonium group of the above-mentioned ammonium group-containing compound include ions such as halogen ions, sulfonates, phosphates, nitrates, alkylsulfonates, and carboxylates.

Further, the number average molecular weight of the compound having an ammonium group is 1,000 to 500,000, preferably 2,000 to 350,000, and more preferably 5,000 to 200,000. If the molecular weight is less than 1000, the strength of the coating layer may be weakened or the heat resistance stability may be poor. Moreover, when the molecular weight exceeds 500,000, the viscosity of the coating liquid becomes high, and handling properties and coating appearance may deteriorate.

In addition, the advantage of compounds with ammonium groups is that they not only suppress the precipitation of oligomer components, but also provide antistatic properties to the coating layer, prevent the adhesion of foreign substances such as dust, and are easy to handle. It is also possible to make it into a film. Particularly from the viewpoint of antistatic properties, compounds having a pyrrolidinium ring and compounds having the structure of the above formula (1) are preferred.

Polyvinyl alcohol is a compound having a polyvinyl alcohol moiety, and for example, conventionally known polyvinyl alcohols can be used, including modified compounds in which polyvinyl alcohol is partially acetalized or butyralized. The degree of polymerization of polyvinyl alcohol is not particularly limited, but it is usually 100 or more, preferably in the range of 300 to 40,000. When the degree of polymerization is less than 100, the water resistance of the coating layer may decrease. Further, although the degree of saponification of polyvinyl alcohol is not particularly limited, a saponified polyvinyl acetate having a degree of saponification of 70 mol% or more, preferably in the range of 70 to 99.9 mol% is practically used.

In order to improve the appearance and transparency of the coating layer, various conventionally known polymers such as polyester resin, acrylic resin, urethane resin, etc. can be used in combination as a binder. Furthermore, in order to improve the film strength, it is also possible to use conventionally known crosslinking agents other than melamine compounds, such as oxazoline compounds, epoxy compounds, and isocyanate group-containing compounds. Furthermore, within the scope of not impairing the gist of the present invention, it is also possible to use a mold release agent such as a fluorine compound, a silicone compound, or a wax in combination to improve blocking resistance and slipperiness.

The coating layer may contain particles from the viewpoint of improving anti-blocking properties and slipperiness. However, from the viewpoint of preventing particles from falling off from the coating layer, it is preferable that substantially no particles are contained.

Here, "substantially no particles" means that no particles are intentionally contained, and takes into consideration the possibility that foreign matter will inevitably be mixed in during the manufacturing process. For example, in the case of inorganic particles, the particle content is usually 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when metal elements or metalloid elements are quantified by XRF (X-ray fluorescence) analysis. It can be defined that there is.

The melamine compound contained in the coating liquid is used in a design to improve the performance of the coating layer by causing a reaction in the drying process when forming the coating layer or during the film forming process. It can be assumed that unreacted melamine compounds, reacted compounds, or a mixture thereof are present in the coating layer formed from the coating liquid.

The content of the melamine compound in the coating solution is preferably in the range of 20 to 70% by mass, more preferably 30 to 60% by mass, even more preferably 40 to 60% by mass, based on the total nonvolatile components in the coating solution. be.
When the content of the melamine compound relative to the total non-volatile components in the coating solution is within the above range, the coating layer formed from the coating solution becomes denser, suppressing the precipitation of oligomer components, and, for example, preventing the formation of the melamine compound from the mold. It is possible to simultaneously satisfy the releasability of

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

The thickness of the coating layer is usually in the range of 0.002 to 1.0 μm, preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.2 μm, particularly preferably 0.01 to 0.1 μm. be. If the thickness is within the above range, precipitation of the oligomer component can be suppressed without hindering roughening of the polyester film surface by the particle-containing layer A (reducing releasability).

The thickness of the coating layer can be measured, for example, by measuring a cross section of the dyed coating layer using a transmission electron microscope (for example, H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV).
Note that the thickness of the coating layer is a value measured at a flat part of the recess in the uneven structure on the surface of the particle-containing layer A side.

The laminated polyester film of the present invention only needs to be provided with a coating layer on one surface of the polyester film provided with the particle-containing layer A, and may be provided with another layer on the surface of the coating layer side. It may be provided with a coating layer on one side and another layer on the other side.

Examples of the "other layers" include an easy-adhesion layer, an antistatic layer, an oligomer sealing layer, an adhesive layer, a release layer, an anti-sticking layer, an anti-blocking layer, and the like.
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 for fixing 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.
Further, 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 the particle-containing layer A is provided on one side of the base layer, and the particle-containing layer B, which is 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. , 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 example, to fix a substrate such as a lead frame in 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 thereof include acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, and the like. 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. If it is less than 1 μm, the adhesiveness may be insufficient, and if it exceeds 500 μm, the adhesiveness may not be stably obtained.

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.

As the resin contained in the easy-adhesion layer, conventionally known resins can be used, such as polyester resins, acrylic resins, urethane resins, polyvinyl resins (polyvinyl alcohol, vinyl chloride-vinyl acetate copolymers, etc.), and the like. . Among these, polyester resins, acrylic resins, and urethane resins are preferred from the viewpoint of adhesion to the polyester film, and acrylic resins are 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, carbodiimide compounds, especially oxazoline compounds and isocyanate compounds are more preferable, and from the viewpoint of increasing the strength of the adhesive 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. , ultraviolet absorbers, foaming agents, dyes, pigments, 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 0.30 μm or more, preferably 0.33 μm or more. Although the upper limit is not particularly limited, it is usually 3 μm or less. When the average surface roughness (Ra) of the coating layer side surface is within the above range, releasability from the mold can be ensured.

The average surface roughness (Ra) of the non-coating layer side surface of the laminated polyester film of the present invention is the average surface roughness (Ra) of the coating layer side surface from the viewpoint of making it easier to laminate a desired layer on the surface. It is preferably smaller than Ra).
Specifically, the average surface roughness (Ra) of the non-coated layer side surface is preferably less than 0.30 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 prevention of blocking.
When the polyester film of the present invention includes 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, the average surface roughness of the surface of the particle-containing layer B is (Ra) is preferably 0.020 μm or more and less than 0.30 μm.

The amount of film haze change (ΔH) on the coated layer side before and after heat treatment (150°C, 90 minutes) of the laminated polyester film of the present invention is preferably 2.0% or less, more preferably 1.5% or less, and still more preferably 1. .0% or less. When ΔH exceeds 2.0%, precipitation of oligomer components may contaminate molds, production lines, products, etc., leading to a decrease in production efficiency and quality.

When using the laminated polyester film of the present invention as a release film for a molding process, it is necessary to visually check the position of substrates such as molds and lead frames through the film, so the optical density (OD value) of the laminated polyester film of the present invention is ) is preferably less than 0.3, more preferably less than 0.1.
On the other hand, when the laminated polyester film requires distinguishability, the optical density (OD value) is preferably 0.3 or more, more preferably 0.4 or more.

The thickness of the laminated polyester film of 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.

An example of a method for manufacturing a semiconductor package will now 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 has excellent releasability while suppressing the precipitation of oligomer components from the polyester film. For example, the laminated polyester film of the present invention can be used as a release film for the molding process of semiconductor packages. , used as a release film for the semiconductor package molding process used in a semiconductor package manufacturing method in which a release film is placed between a lead frame on which a semiconductor chip is installed and a mold, and the mold is filled with mold resin. When it is used, it can prevent contamination of the mold by the oligomer component and has excellent releasability from the mold, so it can be suitably used for the purpose.
However, the application is not limited to the above-mentioned applications, and can also be suitably used, for example, as a transfer film capable of transferring a matte appearance, or as a mold forming film for insert molding, in-mold molding, and the like.

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. Furthermore, 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 Particle size was measured by a sedimentation method using a centrifugal sedimentation type particle size distribution analyzer, model SA-CP3, manufactured by Shimadzu Corporation. The average particle diameter was determined using the value of 50% of the integrated (volume basis) in the equivalent spherical distribution of particles obtained by measurement.

(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 (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV).

(5) Amount of change in film haze due to heat treatment Active energy ray curable resin (product name: Shiko 7600B (manufactured by Mitsubishi Chemical Corporation)) is applied to the side of the laminated polyester film opposite to the coating layer side, and photopolymerization starts. A coating agent (trade name: Irgacure 651 (manufactured by IGM RESINS)) was mixed at a mass ratio of 100/5, diluted with methyl ethyl ketone to a concentration of 30% by mass, and applied to a dry thickness of 3 μm, and exposed to ultraviolet rays. It was irradiated and cured to form a hard coat layer. The haze of the film on which the hard coat layer was formed was measured from the coated layer side using a haze meter ("HM-150", manufactured by Murakami Color Research Institute Co., Ltd.) in accordance with JIS K 7136.
Next, Kent paper was stacked and fixed on the hard coat layer side of the laminated polyester film, and the film was heat-treated by being left at 150° C. for 90 minutes in a nitrogen atmosphere. After the heat treatment, the Kent paper was removed from the laminated polyester film, and the haze of the film was measured from the coating layer side in the same manner as above. The difference between the haze after heat treatment and the haze before heat treatment was calculated and used as the amount of change in film haze.
The lower the change in film haze is, the better it is because it indicates that the amount of oligomer components precipitated from the film due to high-temperature treatment, that is, the amount of ester cyclic trimer precipitated is small.

(6) Peelability The laminated polyester film of the present invention and a stainless steel plate (trade name HS0543) with a thickness of 0.5 mm are cut into 10 cm x 5 cm pieces, the coated layer surface of the laminated polyester film and the stainless steel plate are overlapped, and a heat press machine is used to A sample (a laminate of a laminated polyester film and a stainless steel plate) was prepared by pressing at a temperature of 20 MPa for 5 minutes. Immediately after creating the sample, the laminated polyester film was vertically lifted from a state in which the sample was placed horizontally with the laminated polyester film facing upward, and the peelability was evaluated according to the following criteria.
<Judgment criteria>
◎ (very good): The laminated polyester film peeled off naturally without sticking.
○ (good): There was some sticking, but the laminated polyester film could be peeled off without lifting the stainless steel plate.
△ (usual): Although the stainless steel plate was lifted, it could be peeled off, and there was no problem in practical use.
× (poor): Regardless of whether or not the stainless steel plate can be peeled off, contamination can be confirmed on the stainless steel plate after peeling, which poses a practical problem.

The polyesters used in Examples and Comparative Examples are as follows.
<Polyester (I)>
Polyethylene terephthalate homopolymer (intrinsic viscosity: 0.63 dl/g).
<Polyester (II)>
A polyethylene terephthalate homopolymer (intrinsic viscosity: 0.61 dl/g) containing 10% by mass of alkyl methacrylate-styrene copolymer particles with an average particle size of 4.5 μm.
<Polyester (III)>
A polyethylene terephthalate homopolymer (intrinsic viscosity: 0.61 dl/g) containing 0.7% by mass of silica particles with an average particle size of 2.7 μm.
<Polyester (IV)>
Polyethylene terephthalate homopolymer containing 50% by mass of titanium oxide particles with an average particle size of 0.3 μm

The following composition was used for the coating liquid.
<Melamine compound (C1)>
Hexamethoxymethylolmelamine

<Oxazoline compound (C2)>
Acrylic polymer with oxazoline groups and polyalkylene oxide chains.
(Oxazoline group amount = 7.7 mmol/g, trade name: Epocross (manufactured by Nippon Shokubai Co., Ltd.))

<Long-chain alkyl group-containing compound (R1)>
200 parts of xylene and 600 parts of octadecyl isocyanate were added to a four-necked flask and heated while stirring. From the time the xylene began to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added little by little at 10 minute intervals over about 2 hours. After the addition of polyvinyl alcohol was completed, reflux was further carried out for 2 hours to complete the reaction.
When the reaction mixture was cooled to about 80°C and added to methanol, the reaction product was precipitated as a white precipitate, so this precipitate was filtered off, 140 parts of xylene was added, and the mixture was heated to completely dissolve. After repeating the operation several times by adding methanol again to precipitate, the precipitate was washed with methanol, dried and pulverized to obtain the precipitate.

<Compound containing ammonium group (E1)>
Polymer polymerized with the following composition.
Poly(trimethylammonium ethyl methacrylate methanesulfonate). Number average molecular weight 30000

<Polyvinyl alcohol (P1)>
Polyvinyl alcohol with a saponification degree of 88 mol% and a polymerization degree of 500.

<Aqueous dispersion of acrylic resin polymerized with the following composition: (A1)>
An acrylic resin with a glass transition point of 40°C, which is polymerized using ethyl acrylate, n-butyl acrylate, methyl methacrylate, and N-methylol acrylamide as main monomers.

Example 1:
A mixture of polyester (I) and (II) at a ratio of 50% and 50%, respectively, was used as the raw material for the particle-containing layer A, polyester (I) was used as the raw material for the base layer, and polyester (I) and (III) were mixed at a ratio of 50% and 50%, respectively. A mixture of 70% and 30%, 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 placed on a cooling roll set at 40°C. An unstretched sheet was obtained by coextrusion, cooling, and solidification with a layer structure of 3 types and 3 layers (discharge rate of particle-containing layer A/substrate layer/particle-containing layer B=5:30:3). 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 Solution 1 shown in Table 1 below was applied to the surface of the longitudinally stretched film on the side of the particle-containing layer A. After coating the coating liquid 11 shown in Table 1 below on the surface of the containing layer B side, it was introduced into a tenter, stretched 4.0 times in the transverse direction at 110°C, heat-treated at 225°C, and then stretched by 2% in the transverse direction. A laminated polyester film having a relaxed thickness of 38 μm and having a coating layer having a thickness (after drying) of 0.05 μm and an easily bonding layer having a thickness (after drying) of 0.05 μm was obtained.
The results of each evaluation of the obtained laminated polyester film are shown in Table 2 below.

Examples 2-12:
A laminated polyester film was obtained in the same manner as in Example 1, except that the composition of Coating Solution 1 was changed to that shown in Table 1, and the thickness of the coating layer was further changed in Examples 2 and 4. .
The results of each evaluation of the obtained laminated polyester film are shown in Table 2 below.

Comparative example 1:
A laminated polyester film was obtained by manufacturing in the same manner as in Example 1 except that the coating layer was not provided on the particle-containing layer A side.
The results of each evaluation of the obtained laminated polyester film are shown in Table 2 below. The amount of change in film haze due to heat treatment was 2.1%, indicating that a large amount of oligomer components were precipitated.
Furthermore, in peelability evaluation, the stainless steel plate after peeling was found to be contaminated due to transfer of oligomer components.

The laminated polyester film of the present invention has excellent releasability while suppressing the precipitation of oligomer components from the polyester film. For example, the laminated polyester film of the present invention is used as a release film for the molding process of semiconductor packages. In this case, it is possible to prevent contamination of the mold by the oligomer component and has excellent releasability, so it can be suitably used for the application.

Claims (13)

A coating layer is provided on one surface of the polyester film provided with the particle-containing layer A,
The polyester film includes a particle-containing layer A, a base layer, and a particle-containing layer B different from the particle-containing layer A in this order, and the coating layer is provided on the surface of the particle-containing layer A side of the polyester film. ,
The coating layer is a layer formed from a coating liquid containing a melamine compound,
The average surface roughness (Ra) of the coating layer side surface is 0.30 μm or more,
The particle-containing layer A and the particle-containing layer B contain particles with an average particle size of 2.0 μm or more,
The content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in the particle-containing layer B is equal to the content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in the particle-containing layer A. A laminated polyester film that is 60% or less . The laminated polyester film according to claim 1 , wherein the proportion of the melamine compound in the total nonvolatile components in the coating liquid is 20% by mass or more and 70% by mass or less. The laminated polyester film according to claim 1 or 2, wherein the proportion of the melamine compound in the total nonvolatile components in the coating liquid is 20% by mass or more and 40% by mass or less. A coating layer is provided on one surface of the polyester film provided with the particle-containing layer A,
The polyester film includes a particle-containing layer A, a base layer, and a particle-containing layer B different from the particle-containing layer A in this order, and the coating layer is provided on the surface of the particle-containing layer A side of the polyester film. ,
The coating layer is a layer formed from a coating liquid containing a melamine compound,
The average surface roughness (Ra) of the coating layer side surface is 0.30 μm or more,
A laminated polyester film, wherein the proportion of the melamine compound in the total nonvolatile components in the coating liquid is 20% by mass or more and 40% by mass or less . The particle-containing layer A and the particle-containing layer B contain particles with an average particle size of 2.0 μm or more, and the content of particles with an average particle size of 2.0 μm or more is higher in the particle-containing layer B than in the particle-containing layer A. The laminated polyester film according to claim 4 , wherein the amount of . The content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in the particle-containing layer B is equal to the content (mass%) of particles with an average particle diameter of 2.0 μm or more contained in the particle-containing layer A. The laminated polyester film according to claim 5 , which has a content of 60% or less. The laminated polyester film according to any one of claims 1 to 6, wherein the particle-containing layer B side surface has an average surface roughness (Ra) of 0.020 μm or more and less than 0.30 μm. Claims 1 to 7 , wherein 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. The laminated polyester film according to any one of the above. The laminated polyester film according to any one of claims 1 to 8 , wherein the coating layer contains substantially no particles. The laminated polyester film according to any one of claims 1 to 9 , wherein the coating layer has a thickness of 0.020 μm or more and 1.0 μm or less. The laminated polyester film according to any one of claims 1 to 10 , wherein the amount of change in film haze on the coated layer side before and after heat treatment at 150° C. for 90 minutes is 2.0% or less. A release film for a semiconductor package molding process using the laminated polyester film according to any one of claims 1 to 11 . According to claim 12 , the release film is disposed between a lead frame on which a semiconductor chip is installed and a mold, and is used as the release film used in a method for manufacturing a semiconductor package in which the mold resin is filled in the mold. Release film for the molding process of semiconductor packages.