JP2010201858A - Biaxially-oriented polyester film for molding simultaneous transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially-oriented polyester film molding simultaneous transfer which has large film surface roughness, is excellent in moldability, and can omit the processing of a release layer when a transfer sheet is processed. <P>SOLUTION: The biaxially-oriented polyester film for molding simultaneous transfer includes at least two coextruded layers. One surface layer is formed of a mixture comprising copolymerized polyester and polyethylene terephthalate or copolymerized polyester and contains 0.3-20 wt.% of particles having an average particle size of 1.0-20 μm, has a melting point lower by at least 5°C than the melting points of the other layer, and includes a coating layer containing 7-50 wt.% of wax. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biaxially stretched polyester film for simultaneous molding transfer that is useful as a base film for a simultaneous molding decorative sheet used to decorate the surface of a resin molded product such as an electric product or an automobile part in a matte tone.

  As a method for decorating a plastic molded product having a curved surface such as an electric appliance, a so-called in-mold molding method in which transfer printing is performed simultaneously with molding is widely used. The in-mold molding method is to create a transfer sheet in which a printing layer consisting of a release layer, a surface protective layer, an ink layer, an adhesive layer, etc. is laminated on the base film in advance, and the heat during plastic injection molding This is a transfer printing method using pressure. The present invention eliminates the step of applying a release layer during transfer sheet processing, and is a biaxially stretched polyester film for simultaneous transfer molding that is used to create a matte appearance with excellent matting on the surface of a molded product About.

  The substrate film has fine irregularities on the surface in order to transfer the matte appearance to the molded product. There are methods for providing fine irregularities on the surface of the base film, such as embossing and a method of coating a coating solution containing fine particles, but there is a problem that the manufacturing process of the base film increases. Moreover, although the polyester film for simultaneous transcription | transfer at the time of roughening the surface by adding a comparatively large amount of particle | grains at the time of polyester film manufacture is disclosed by patent document 1, it cannot be said that the glossiness of a molded product is low enough. On the other hand, if the particle concentration in the film is increased in order to increase the film surface roughness, there arises a problem that the film is torn during the simultaneous transfer processing.

  In Patent Document 2, as a release film for a simultaneous molding transfer sheet, a coating liquid mainly composed of a mixed resin of a thermosetting resin and a thermoplastic resin is applied to a biaxially stretched polyester film to form a release layer. Although a release film is disclosed, there is no significant difference from applying a release layer during transfer sheet processing.

JP 2007-268708 A JP 2000-301665 A

  The present invention has been made in view of the above-mentioned actual situation, and the problem to be solved is that even when the film particle concentration is low, a molded product having a large surface roughness, excellent moldability and low gloss can be obtained. The function that the coating layer provided on the film surface in the stretched film manufacturing process does not peel off at the interface between the coating layer and the surface protective layer during transfer sheet processing or slitting of the transfer sheet, and smoothly peels off at the interface after simultaneous molding processing It is to provide a biaxially stretched polyether film for simultaneous molding transfer having

  As a result of intensive studies, the present inventors have found that the above problem can be easily solved by using a polyester film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is a polyester film composed of at least two coextruded layers, and one surface layer is composed of a mixture of copolymerized polyester and polyethylene terephthalate or a copolymerized polyester, and the average particle size is in the surface layer. It has a coating layer containing particles of 1.0 to 20 μm in an amount of 0.3 to 20% by weight, the melting point of the surface layer being 5 ° C. lower than the melting point of the other layers, and containing 7 to 50% by weight of wax. The feature resides in a biaxially stretched polyether film for simultaneous molding transfer.

Hereinafter, the present invention will be described in detail.
The film of the present invention is a film having at least two coextruded layers, that is, a layer A (sublayer) containing particles and another layer B. A single layer is not preferable because the amount of particles added increases in order to increase the film surface roughness. Moreover, the structure of a layer can take the structure of A / B layer, A / B / A layer, and A / B / C layer, and A layer comprises the surface layer of the at least single side | surface of a film.

  Polyesters used for the B layer are polyethylene terephthalate (PET) produced from ethylene glycol and terephthalic acid, polyethylene-2,6-naphthalate (PEN) produced from ethylene glycol and naphthalene-2,6-dicarboxylic acid, 1, Poly (1,4-cyclohexanedimethylene terephthalate) (PCDT) produced from 4-bishydroxymethylcyclohexane and terephthalic acid, from ethylene glycol, naphthalene-2,6-dicarboxylic acid and biphenyl-4,4′-dicarboxylic acid The poly (ethylene 2,6-naphthalate bibenzoate) (PENBB) produced is exemplified. Among them, it is preferable to contain an ethylene terephthalate unit composed of ethylene glycol and terephthalic acid and / or an ethylene-2,6-naphthalate unit composed of ethylene glycol and naphthalene-2,6-dicarboxylic acid, and these units are 90% or more. A polyester containing 95% or more is preferable.

  The polyester used in the A layer is a copolyester or a mixture of copolyester and polyethylene terephthalate. Copolyester is an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, ethylene glycol, diethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol The main component is an ester with a glycol such as the above, 30 mol% or less of the dicarboxylic acid component is a dicarboxylic acid component other than the main component, and / or 30 mol% or less of the diol component is a diol component other than the main component. Some polyester.

  The polyester can be obtained by directly polymerizing an aromatic dicarboxylic acid and a glycol, or by a transesterification reaction between an aromatic dicarboxylic acid dialkyl ester and a glycol, followed by polycondensation, or an aromatic dicarboxylic acid diglycol. It can also be obtained by a method such as polycondensation of an ester. Typical examples of the polyester include a copolymer of terephthalic acid (main component) isophthalic acid (subcomponent) and ethylene glycol, and a copolymer of terephthalic acid, ethylene glycol (main component) propylene glycol (subcomponent). There is.

  Further, the melting point of the polyester of the A layer containing particles needs to be lower by 5 ° C. or more than the polyester constituting the other layers. If the difference between the melting points is less than 5 ° C., the heat setting temperature in the film forming process approaches the melting point of the film, so that the film tends to break in the transverse stretching process. Further, since the voids formed around the particles of the A layer are increased, the film is liable to be broken at the time of simultaneous forming and molding. Further, the melting point of the polyester of the A layer is preferably 190 ° C. or higher, more preferably 200 ° C. or higher. When the melting point of the polyester of the A layer is less than 190 ° C., the heat setting temperature of the film is 184 ° C. at the maximum. Changes in the thermal dimension of the substrate film due to the influence of the drying temperature during printing may increase and cause printing misalignment.

  The particles contained in the A layer are inorganic or organic particles, and the average particle size thereof is 1.0 to 20 μm, preferably 2.0 to 15 μm, more preferably 2.5 to 10 μm. When the average particle size is less than 1.0 μm, the surface roughness becomes small, and a molded product having excellent matting properties cannot be produced. On the other hand, when the average particle diameter exceeds 20 μm, a problem arises in that the increase in the pressure of the filter in the polyester extrusion process during film production increases and the productivity decreases.

  The content of such particles is 0.3 to 20% by weight or less, preferably 0.5 to 15% by weight with respect to the A layer. If it is less than 0.3% by weight, it is difficult to increase the film surface roughness. On the other hand, addition exceeding 20% by weight makes it difficult to produce a high-concentration particle masterbatch, and cannot be substantially added.

  The inorganic or organic particles used in the present invention may be a single component, or two or more components may be used simultaneously. Specific examples of the particles include inorganic fine particles such as calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, and glass, and organic particles such as melamine resin, polystyrene, organic silicone resin, and acrylic-styrene copolymer. It is done.

  The ratio that the thickness of the A layer of the film of the present invention occupies the thickness of the entire film is usually 1 to 20%. If the ratio is less than 1%, the film surface roughness tends not to be sufficiently increased, and if it exceeds 20%, the film strength decreases.

  In this invention, it is preferable that the heat setting temperature of a film manufacturing process shall be melting | fusing point (Tm) -6-Tm-18 degreeC of A layer, More preferably, it is the range of Tm-7-Tm-15 degreeC. When the heat setting temperature exceeds Tm-6, the film surface roughness decreases. On the other hand, even if the heat setting temperature is less than Tm-18, the surface roughness tends to decrease and the elongation at break tends to decrease. After biaxial stretching, a film having the maximum film surface roughness can be obtained by heat treatment in the temperature range of Tm-6 to Tm-18 ° C.

  The reason why the film surface roughness is maximized is not clear, but the polyester constituting the A layer has a component having a melting point lower than Tm and a component having a higher melting point, and the stretch orientation of a part of the component having a melting point lower than Tm is canceled. It is thought that this phenomenon was manifested.

Although the 25 degreeC breaking elongation of the film of this invention is based also on the metal mold | die shape of the target molded article, Preferably it is 150% or more, More preferably, it is 160% or more, Most preferably, it is 170% or more. If the 25 ° C. elongation of the film is less than 150%, the film may be broken during the simultaneous molding and transfer process.

  The surface roughness Sa of the film of the present invention is preferably 200 nm or more, more preferably 220 nm or more, and particularly preferably 250 nm or more. If the surface roughness Sa is less than 200 nm, it is impossible to produce a mat-like molded simultaneous transfer molded product with excellent matting properties. The matte tone with excellent matting properties of the present invention means that the gloss of the molded product is 90 or less, and therefore the gloss of the film is at least 90, preferably 80 or less, particularly preferably 60 or less. It is necessary to be.

  In the present invention, the coating layer is provided on the surface of the layer A, and the coating layer contains 7 to 50% by weight, preferably 10 to 40% by weight of wax. If the wax content is less than 7% by weight, the printed layer remains on the base film side because the peelability is too bad. On the other hand, if the wax content exceeds 50% by weight, the releasability is too good, and the printed layer may fall off during transfer sheet processing, during transfer sheet slit processing or during molding processing.

  In the present invention, wax is used as one of the components constituting the coating layer. Examples of the wax include vegetable wax to which candelilla wax and carnauba wax belong, petroleum wax to which paraffin wax and microcrystalline wax belong, hydrogenated wax to which hardened castor oil and the like belong. Among these, waxes classified into petroleum wax, synthetic hydrocarbon wax and modified wax can be preferably used from the viewpoint of affinity with a polyester film. In addition, the use of modified waxes, such as polyethylene oxide wax, which is a synthetic hydrocarbon wax that is oxidized by an oxidation method such as air oxidation to add a carboxyl group or a hydroxyl group, is difficult to remove. Is particularly preferable.

  Furthermore, the coating layer may contain a crosslinking reactive compound as required. The cross-linking reactive compound is preferable because it can improve the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer mainly through a cross-linking reaction with a functional group contained in the wax or self-crosslinking. As the crosslinking reactive compound that can be used, amino resins such as melamine, benzoguanamine, and urea, oxazoline, and epoxy are preferably used. Polymer-type cross-linking reactive compounds having reactive groups in other polymer skeletons are also included.

  If necessary, one or two or more water-soluble or water-dispersible binder resins can be used in combination. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and the like. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  The coating layer in the present invention includes a surfactant, an antifoaming agent, a coating property improving agent, a thickener, an antistatic agent, an organic lubricant, organic particles, inorganic particles, an antioxidant, an ultraviolet absorber, and a foaming agent. , And may contain additives such as dyes and pigments. These additives may be used alone or in combination of two or more as required.

  The coating layer according to the present invention can be provided by in-line coating performed during the formation of the biaxially stretched polyester film, offline coating performed after the film is formed, or other methods. In particular, in the present invention, it is preferably provided by in-line coating.

  In-line coating is a method of coating in the process of manufacturing a polyester film. Specifically, it is a method of coating at any stage from melt extrusion of polyester to biaxial stretching and then heat setting and winding. is there. Normally, it is coated on either a substantially amorphous unstretched sheet obtained by melting and quenching, then a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction), or a biaxially stretched film before heat setting. To do. Among these, a method in which a uniaxially stretched film is coated, dried in a tenter and stretched in the transverse direction, and further heat treated together with the base film is excellent. According to such a method, since film formation and coating layer coating can be performed simultaneously, there is a merit in manufacturing cost, thin film coating is easy to perform stretching after coating, and heat treatment applied after coating is other than that. Since the high temperature is not achieved by this method, the film forming property of the coating layer is improved, and the polyester film is firmly adhered to the coating layer. In particular, when used as a polyester film for simultaneous molding transfer, it is not preferable that the coating layer breaks or peels in the layer or between the film, but the coating layer by in-line coating shows an excellent aspect in this respect. . In particular, when the coating layer contains a cross-linking reactive compound, there is an advantage that the reaction residue hardly remains due to the high-temperature treatment of in-line coating. When used as a base film for simultaneous molding transfer, the presence of a reactive residue in the coating layer is undesirable because it may react with the components of the surface protective layer in the processing step for the transfer sheet and deteriorate the peelability.

  As a method of applying the coating solution to the polyester film, for example, a coating technique as shown in “Coating system” published by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater And techniques such as an extrusion coater and a bar coater.

  The coating solution used in the present invention is preferably an aqueous solution or an aqueous dispersion for handling and working environment, but contains water as the main medium and contains an organic solvent as long as it does not exceed the gist of the present invention. You may do it.

The coating amount of the coating layer is usually 0.003~1.5g / ^{m 2,} preferably not 0.005 to 0.5 / ^{m 2,} more preferably at 0.01 to 0.3 g / ^{m 2.} If the coating amount of the coating layer is less than 0.003 g / m ^2, sufficient performance may not be obtained. A coating layer exceeding 1.5 g / m ² is not preferable because it deteriorates the appearance and increases the cost. .

  In the present invention, a coating layer such as an antistatic layer or an easy adhesion layer may be provided on the surface opposite to the surface of the A layer, or chemical treatment or discharge treatment may be performed as necessary.

  Next, although the manufacturing method of the film of this invention is demonstrated concretely, as long as the structural requirements of this invention are satisfied, it is not specifically limited to the following illustrations.

  When the film of the present invention is produced, the polyester is supplied to at least two extruders, heated to a temperature equal to or higher than the melting point of each polyester, and melted. Next, the molten polymer from each extruder is merged with a feed block through a gear pump and a filter and extruded from a die as a molten sheet. Subsequently, the molten sheet is rapidly cooled to below the glass transition temperature on a rotary cooling drum to obtain an amorphous unstretched film. At this time, in order to improve the flatness of the unstretched film, the adhesion between the unstretched film and the rotating cooling drum may be improved by an electrostatic application adhesion method, a liquid application adhesion method, or the like.

  And a uniaxially stretched film is obtained by extending | stretching an unstretched film in the longitudinal direction (longitudinal stretching) using a roll stretching machine. The stretching temperature at this time is stretched in a temperature range of minus 10 ° C. to plus 40 ° C. of the glass transition temperature (Tg) of the raw material resin. The draw ratio is preferably 1.5 to 6.0 times, more preferably 2.0 to 5.0 times. Furthermore, longitudinal stretching may be performed in only one stage, or may be performed in two or more stages. Next, an aqueous coating solution having a predetermined composition in which wax, resin, or the like is dispersed is applied with a Mayer bar. Next, the biaxially stretched film is obtained by stretching the uniaxially stretched film in the width direction (lateral stretching) using a tenter stretching machine. The stretching temperature at this time is stretched in a temperature range of + 50 ° C. from the glass transition temperature (Tg) of the raw material resin. The draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.0 times. Further, the transverse stretching may be performed only in one stage, or may be performed in two or more stages. Moreover, you may perform simultaneous biaxial stretching which performs vertical and horizontal simultaneously.

  And a laminated film is manufactured by heat-processing a biaxially stretched film. At this time, the heat setting temperature is usually Tm-6 to Tm-18 ° C., and the heat setting time is usually 1.5 to 10 seconds. Moreover, when heat-treating a biaxially stretched film, the biaxially stretched film may be relaxed within 20%.

  In the present invention, the surface layer of the coextruded layer is blended with specific particles and a polyester resin, and a coating layer containing a specific amount of wax is provided on the surface when producing a biaxially stretched film, so that the surface roughness is low even when the film particle concentration is low. It is possible to provide a biaxially stretched polyether film for simultaneous molding and molding, which is large in size, excellent in moldability, and can eliminate the processing of the release layer during processing of the transfer sheet, and the industrial value of the present invention is high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement methods and terms used in the examples and the present invention are defined as follows.

(1) Average particle diameter of layer A After ashing the surface in the film stretching direction to 1 μm with a low-temperature ashing plasma apparatus, at least the major axis and minor axis of particles having a particle diameter of 1 μm or more are measured with a scanning electron microscope. It calculates | requires about 100 pieces and makes an arithmetic mean the average particle diameter.

(2) Elongation at break 50 mm between chucks taken in the vertical and horizontal directions in a room adjusted to a temperature of 25 ° C. and a humidity of 50% RH using an Intesco tensile tester, Intesco Model 2001 type A sample film with a width of 15 mm is pulled at a speed of 200 mm / min, and each N = 3 times is measured, and the average value is taken as the breaking elongation of the sample.

(3) Surface layer A roughness Sa
Measurement is performed using a three-dimensional non-contact surface shape measurement system MN537N-M100 (Ryoka System Co., Ltd.).

(4) Melting point of polyester Using a MD instrument 2910 manufactured by TA Instruments Inc., a polyester raw material or a film sample sample was heated and melted at 300 ° C. and then rapidly cooled and measured from 0 ° C. to 300 ° C. at a heating rate of 20 ° C./min. The endothermic peak temperature in crystal melting is taken as the melting point.

(5) Glossiness Measured by incident light on the film on the surface of the single-layer film or the surface of the A-layer according to method 3 (60 ° glossiness) of JIS Z-8741-1983.

(6) Evaluation of Peeling Property After applying an acrylic pressure-sensitive adhesive tape (“Nitto Denko“ No. 31B ”) having a similar composition to the surface protective layer provided at the time of processing the transfer sheet on the surface of the polyester film coating layer, the room temperature is The peel strength after standing for 1 hour is measured. The measurement was carried out using a tensile tester (“Intesco Model 2001” manufactured by Intesco Co., Ltd.), and 180 ° peel force measurement was performed under the condition of a tensile speed of 300 mm / min.
○: Peeling force is 1000 or more and 3000 mN or less and suitable for a molding simultaneous transfer sheet. × −a: Peeling force is less than 1000 nN, making transfer sheet difficult. × −b: Partially on the film surface after measuring peeling force. Acrylic adhesive remains

(Raw material adjustment)
・ Polyester a
100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol are used as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is gradually distilled off. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to this reaction mixture, 0.04 part of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The obtained polyester a has an intrinsic viscosity of 0.63 and a melting point of 253 ° C.

・ Polyester b
This is a copolyester resin having an intrinsic viscosity of 0.70 and a melting point of 198 ° C., which is obtained by synthesizing a copolyester containing 22 mol% of isophthalic acid using dimethyl terephthalate, dimethyl isophthalate and ethylene glycol.

・ Polyester c
Polyester a is kneaded with 10% by weight of crosslinked styrene-acrylic organic particles having an average particle diameter of 4 μm.

・ Polyester d
Polyester a is kneaded with 4% by weight of crosslinked styrene-acrylic organic particles having an average particle size of 6 μm.

・ Polyester f
A synthetic calcium carbonate particle having an average particle diameter of 0.7 μm was added during polycondensation of polyethylene terephthalate, and was synthesized with a polyethylene terephthalate resin having an intrinsic viscosity of 0.68 with a particle content of 1.0% by weight and a melting point of 253 ° C. is there.

Polyester g
Polyester a is kneaded with silica particles having an average particle size of 80 μm and contains 10% by weight.

Moreover, the following was used as a component which comprises a coating liquid.
(A-1): Oxidized polyethylene wax (Hitech manufactured by Toho Chemical)
(B-1): Polymethylmethacrylate graft polyester (manufactured by Takamatsu Yushi)
(C-1): Cross-linking reactive compound of alkylol melamine / urea copolymer (Beccamin manufactured by Dainippon Ink & Chemicals, Inc.)

Example 1:
Polyester comprising polyester / polyester b / polyester c ratio of 31/36/33 (weight ratio) forming the surface layer (A layer) to a twin-screw extruder with a vent (sub) and constituting an intermediate layer a is supplied to another twin-screw extruder with a vent (main) and melted at a melting temperature of 280 ° C., and then the molten polymer from each extruder is merged with a feed block through a gear pump and a filter, and a casting drum is passed through a die. 2 types and 3 layers of unstretched films were obtained. The unstretched film thus obtained was fed into a longitudinal stretching roll and first stretched 3.0 times at a film temperature of 83 ° C., and then a coating composition having the composition shown below was applied to one side of the uniaxially oriented film. It led to the next tenter and was stretched 3.6 times in the transverse direction at 95 ° C. to obtain a biaxially oriented film. Next, the obtained biaxially oriented film was guided to a heat setting zone, heat-treated at 215 ° C., and a coating layer having an amount of 0.05 g / m ² was laminated on the base film, and the thickness described in Table 1 below. A polyester film was obtained.
Coating solution composition: (A-1) / (B-1) / (C-1) = 20/60/20 (weight ratio)

Example 2:
A film was obtained in the same manner as in Example 1 except that the following coating solution composition was used.
Coating liquid composition: (A-1) / (B-1) / (C-1) = 10/80/10 Weight ratio

Example 3:
A film was obtained in the same manner as in Example 1 except that the following coating solution composition was used.
Coating solution composition: (A-1) / (B-1) / (C-1) = 40/20/40 (weight ratio)

Comparative Example 1:
A film was obtained in the same manner as in Example 1 except that the coating layer was not provided.

Comparative Example 2:
Same as Example 1 except that the following coating solution composition was used.
Coating solution composition: (A-1) / (B-1) / (C-1) = 5/90/5 (weight ratio)

Comparative Example 3:
A film was obtained in the same manner as in Example 1 except that the following coating solution composition was used.
Coating solution composition: (A-1) = 100 (% by weight)

Comparative Example 4:
Using a mixture in which the ratio of polyester a / polyester b / polyester e is 20/55/25 (weight ratio), the draw ratio in the longitudinal direction is 3.5 times, the draw ratio in the transverse direction is 4.0 times, and heat A 50 μm single layer film was obtained at a fixing temperature of 180 ° C. A coating layer was not provided.

Comparative Example 5:
A film having a ratio of polyester a / polyester c of 81/19 (weight ratio) was used for the surface layer (A layer) to obtain a film described in Table 2 below. A coating layer was not provided.

Comparative Example 6:
A film having a ratio of polyester a / polyester f of 30/70 (weight ratio) was used for the surface layer (A layer) to obtain the film described in Table 2. A coating layer was not provided.

Comparative Example 7:
A film having a ratio of polyester a / polyester c of 98.3 / 1.7 (weight ratio) was used for the surface layer (A layer) to obtain a film described in Table 2. A coating layer was not provided.

Comparative Example 8:
Film formation was attempted in the same manner as in Example 1 using polyester g instead of polyester c, but the production of the film was abandoned because of an increase in the pressure of the filter in the polyester extrusion process during film production.

Comparative Example 9:
A polyester master a was kneaded with crosslinked styrene-acrylic organic particles having an average particle size of 4 μm to make a particle masterbatch containing 30% by weight. However, a film in which 20% by weight of particles were added to the surface layer without forming a resin chip was obtained. could not.

  The evaluation results of the films that have been collected are summarized in Tables 1 and 2 below.

  The films of Examples 1 to 3 have a large surface roughness even when the film particle concentration is low, and can form a molded product having excellent moldability and low glossiness. It is a film that does not peel off at the interface between the coating layer and the surface protective layer, and has a function of smoothly peeling off at the interface after molding simultaneous transfer processing even if there is no release layer in the printing layer. In Comparative Example 1, since there is no coating layer, it cannot be smoothly peeled off at the surface protective layer and the film interface. In Comparative Example 2, since the added amount of wax contained in the coating solution is low, it cannot be smoothly peeled off at the interface between the surface protective layer and the film. In Comparative Example 3, since the amount of added wax is large, the strength at the interface between the surface protective layer and the film is small and the film is easily peeled off and cannot be processed into a transfer sheet. Since Comparative Example 4 is a single layer film, the particle concentration is large. In Comparative Example 5, since no copolyester is used for the surface layer, the breaking elongation of the film is small and the moldability is poor. Comparative Example 6 has a small surface layer particle size, and Comparative Example 7 has a small surface roughness due to the small particle concentration of the surface layer, making it impossible to produce a mat-like molded product with excellent matting properties.

  The film of the present invention can be suitably used, for example, as a base material for simultaneous molding transfer.

Claims (1)

It is a polyester film composed of at least two coextruded layers, and one surface layer is made of a mixture of copolymerized polyester and polyethylene terephthalate or copolymerized polyester, and particles having an average particle size of 1.0 to 20 μm are contained in the surface layer. 2 for molding simultaneous transfer, characterized by having a coating layer containing 0.3 to 20% by weight, the melting point of the surface layer being 5 ° C. or more lower than the melting point of the other layers, and containing 7 to 50% by weight of wax. Axial stretched polyester film.