JP2001200073A - Polyester film for lamination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a polyester film for lamination which is excellent not only in environmental friendliness but also in embossability and foldability. SOLUTION: In the expansion and contraction curve of the polyester film in the temperature rise under a load of 0.1 Mpa, T1 and T2 of the film satisfy the relation represented by the equation: T2-T1>=8( deg.C), wherein T1( deg.C) is the highest temperature at which the slope of the expansion and contraction curve in the temperature rise changes from a negative value to a positive value; and T2( deg.C) is the temperature at which the expansion in the temperature rise reaches 25%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to metal, wood, paper,
The present invention relates to a polyester film which is used by being bonded to a resin or the like, has excellent flexibility, and can be preferably used for embossing, bending and the like. More specifically, the present invention relates to a polyester film for lamination suitable for a decorative sheet or a decorative board used for a building material or the like.

[0002]

2. Description of the Related Art Hitherto, as a film used for embossing in a building material application, a polyvinyl chloride film is typical, and has been preferably used in terms of flexibility, weather resistance, embossability and the like. . On the other hand, the film has a problem of toxic gas generation when the film is burned due to a fire, a problem of bleed out of a plasticizer, and the like.
In recent years, new materials have been demanded due to the need for environmental resistance.

In order to solve these demands, for example, there is a method of laminating a transparent polyester film on a layer on which a picture is printed. However, a conventional polyester film has insufficient embossing property and improvement is desired. I was

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a polyester film for lamination which is not only excellent in environmental performance but also excellent in embossing and bending. To provide.

[0005]

According to the present invention, a stress of 0.1 M is applied.
A polyester film for lamination characterized by satisfying the following T1 and T2 defined by an expansion / contraction curve when a load of Pa is applied and the temperature is raised.

T1 (° C.): The highest temperature at which the slope of the expansion / contraction curve changes from a negative value to a positive value at the time of temperature rise. T2 (° C.): Temperature at which the elongation at the time of temperature rise reaches 25% T2−T1 ≧ 8 (° C) (Equation 1)

BEST MODE FOR CARRYING OUT THE INVENTION The polyester in the present invention is a generic term for a high molecular weight compound constituted by an ester bond.

The dicarboxylic acid component used for this ester bond includes, for example, terephthalic acid, isophthalic acid,
Naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfondicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoisophthalic acid, aromatic dicarboxylic acids such as phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, Aliphatic dicarboxylic acids such as maleic acid and fumaric acid, alicyclic dicarboxylic acids such as cyclohexyne dicarboxylic acid, and oxycarboxylic acids such as p-oxybenzoic acid can be used.

Of these, the proportion of terephthalic acid in the polyester of the present invention is preferably 95 mol% or more from the viewpoint of heat resistance and productivity.

On the other hand, examples of glycol components include ethylene glycol, propanediol, butanediol,
Aliphatic glycols such as pentanediol, hexanediol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, and diethylene glycol can be used. In addition, two or more of these dicarboxylic acid components and glycol components may be used in combination.

Further, as long as the effects of the present invention are not impaired, it is also possible to use a copolymerized polyester obtained by copolymerizing a polyfunctional compound such as trimellitic acid, trimesic acid, and trimethylolpropane.

It is preferable to use a blend of two or more of the above polymers in order to improve the effects of the present invention. Among them, a mixed polymer of polyethylene terephthalate and polypropylene terephthalate is particularly preferred from the viewpoint of flexibility. For example, at least two kinds of polyethylene terephthalate of 5 to 99% by weight and polypropylene terephthalate of 1 to 95% by weight are described. Is preferred. More preferably, it is 30 to 99% by weight of polyethylene terephthalate and 1 to 70% by weight of polypropylene terephthalate, and particularly preferably 50 to 95% by weight of polyethylene terephthalate and 5 to 50% by weight of polypropylene terephthalate. Exceeding the above upper limit is not preferred because it is below the lower limit and the workability is reduced. Other combinations of polymers (for each combination, the numerical range of the above-mentioned weight% is applied in the order of the monomer molecular weight) are almost the same.

Also, in addition to the two polyesters,
Other resins may be mixed or kneaded.

The melting point of the polyester film in the present invention is preferably from 200 to 2 from the viewpoint of heat resistance and processability.
70 ° C, more preferably 220 to 270 ° C, particularly preferably 246 to 270 ° C. Here, the melting point of the polyester film refers to an endothermic peak temperature at the time of melting, which is detected at the time of the first temperature rise (1st Run) in so-called differential temperature calorimetry (DSC).

The polyester film of the present invention is desirably biaxially stretched from the viewpoint of heat resistance and dimensional stability. Such a biaxial stretching method may be any of simultaneous biaxial stretching and sequential biaxial stretching.

The polyester film of the present invention can be prepared by using different kinds of polyesters, for example, as disclosed in JP-A-9-245.
No. 88, it can be a laminated structure. The form of the laminated film is not particularly limited, and examples thereof include A / B, B / A / B, and C / A / B lamination.

The total thickness of the polyester film for lamination of the present invention is preferably from 3 to 1000 μm, more preferably from 20 to 300 μm, in view of moldability, coatability on a substrate, and design. Preferably 50
２００200 μm.

In order to achieve the object of the present invention, it is necessary that the following T1 and T2 defined in the expansion and contraction curve when a load of stress of 0.1 MPa is applied and the temperature is raised satisfy (Equation 1). (T1 and T2 of typical extension curves are shown in FIG. 1.) T1 (° C.): The highest temperature at which the slope of the expansion / contraction curve changes from a negative value to a positive value at the time of temperature rise. Temperature at which elongation at warm reaches 25% T2−T1 ≧ 8 (° C.) (Equation 1) Here, T1 is a temperature at which stretching can be performed with a small load, that is, a temperature at which processing becomes easy, and T2−T1 Indicates a temperature range in which processing can be easily performed. The larger the value is, the more preferable in terms of workability. More preferably, (Equation 1) is T2
−T1 ≧ 12, particularly preferably T2−T1 ≧ 20
It is. There is no particular upper limit, but T2-
It is preferable that T1 ≦ 200.

Means for achieving the above formula 1 include a method using two or more kinds of mixed polymers, particularly preferably a method using a mixed polymer of polyethylene terephthalate and polypropylene terephthalate, and more preferably a method using Tg in stretching a film. (Tg is the glass transition point, the same applies hereinafter) +20 to Tg + 40 ° C. preheating for 3 to 20 seconds,
A method of stretching at a temperature of Tg + 25 to Tg + 60 ° C. and a method of setting a stretching ratio so that the plane orientation coefficient is 0.15 or less (preferably 0.14 or less) are exemplified, but not limited thereto.

In the present invention, in order to improve the adhesion between the film and the substrate, the heat shrinkage stress in the longitudinal direction of the film at 150 ° C. is preferably 0.1 to 5.0 MPa, more preferably 0.2 to 5.0 MPa. 3.0 MPa.

From the viewpoint of adhesion and workability, particularly, suppression of film wrinkling at the time of processing, the melting point (Tm) of the film is 5 times.
Longitudinal thermal shrinkage of the film when heated for 5 minutes at 0 ℃ low temperature S _MD (%), the width direction of the heat shrinkage factor S _TD (%)
Preferably satisfy the following (Equation 2) and (Equation 3). _{| S MD + S TD | /} 2 ≦ 8 ··· ( Equation 2) | S _MD -S _TD | at ≦ 8 · · · (Equation 3) Here, if the melting point of the polyester film appears two or more, the lowest The melting point is defined as Tm in this case. |
_{S MD + S TD | / 2} ≦ 5, | S MD -S TD | more preferably _{≦ 5, | S MD + S} TD | / 2 ≦ 3, | S MD -
It is particularly preferred that S _TD | ≦ 3.

From the viewpoint of workability, the elongation at break at 180 ° C. is preferably 300% or more, and more preferably 40% or more.
0% or more. There is no particular upper limit to the preferred range, and the larger the size, the easier it is to process, but it is usually about 2000%.

When the present invention is made into a biaxially stretched film, the plane orientation coefficient is preferably from 0.030 to 1.0 mainly from the viewpoint of processability.
0.170, more preferably 0.050 to 0.1
60, particularly preferably 0.080 to 0.15. The plane orientation coefficient (fn) is a value calculated from the refractive indices (Nx, Ny, Nz, respectively) in the longitudinal direction, the width direction, and the thickness direction measured using an Abbe refractometer or the like. ). Plane orientation coefficient: fn = (Nx + Ny) / 2-Nz (Equation 4) If the plane orientation coefficient is 0.030 or less, whitening may occur during processing, which is not preferable. Is not preferred.

In the film of the present invention, the total haze of the film is preferably at most 20%, particularly preferably at most 15%. If it exceeds 20%, it is not preferable because the design property deteriorates depending on the use.

Further, it is preferable that the rate of increase in internal haze after heat treatment at 180 ° C. for 10 minutes is small, preferably, the rate of increase is 80% or less, more preferably 40% or less, and particularly preferably 20% or less. If it exceeds 80%, whitening during processing becomes remarkable, which is not preferable.

In the present invention, from the viewpoint of improving the adhesiveness and processability between the film and the substrate, the carboxyl terminal group content is
Preferably 20 to 60 equivalents / ton, more preferably 3
Those having 0 to 50 equivalents / ton are preferred.

In the present invention, the intrinsic viscosity of the polyester is preferably 0.50 dl / g or more, more preferably 0.55 d / g, in order to further improve the adhesive property and the stability of film formation.
Those having a l / g or more, particularly preferably 0.60 dl / g or more, are used. If the intrinsic viscosity is less than 0.50 dl / g, the adhesiveness is undesirably reduced. The upper limit is not particularly limited, but is preferably 1.5 dl / g or less. If it exceeds this value, it becomes difficult to perform filtration during the usual extrusion.

The catalyst for producing the polyester of the present invention is not particularly limited, but may be an alkaline earth metal compound, a manganese compound, a cobalt compound, an aluminum compound, an antimony compound, a titanium compound, a titanium / silicon composite oxide, a germanium compound. Etc. can be used.
Among them, a titanium compound, a titanium / silicon composite oxide, and a germanium compound are preferable in setting the catalytic activity, taste characteristics, and the amount of the catalytic metal.

For example, when a titanium / silicon catalyst is added as a catalyst, a terephthalic acid component and an ethylene glycol component are reacted, and then a titanium / silicon composite oxide and a phosphorus compound are added. And a method of obtaining a polyester having a specific amount of a catalytic metal and a specific amount of phosphorus by a polycondensation reaction until the content of diethylene glycol reaches the above.

The phosphorus compound added as a heat stabilizer is not particularly limited, but phosphoric acid and phosphorous acid are preferred.

In the polyester film of the present invention, in order to make the design and weather resistance extremely good, the remaining amount of catalyst metal (M: unit mmol%) and the remaining amount of phosphorus element (P: unit mmol%) Is preferably less than 1. More preferably, M / P is 0.3 or more and less than 1. In particular, when the ratio is 0.5 or more and less than 1, the productivity of the film does not deteriorate, so that it is more preferable.

The method for producing the polyester film in the present invention is not particularly limited. For example, after drying the polyester as required, it is supplied to a known melt extruder, extruded into a sheet from a slit die, and then statically extruded. Adhere to the casting drum by a method such as applying electricity,
After cooling and solidifying to obtain an unstretched sheet, the unstretched sheet is stretched. Such a stretching method may be any of simultaneous biaxial stretching and sequential biaxial stretching. In short, the unstretched sheet is stretched in the longitudinal direction and the width direction of the film, and heat-treated to obtain a film having a desired plane orientation degree. The method is adopted. Among these systems, preferably, in terms of film quality, a tenter system is preferable, and after stretching in the longitudinal direction, a sequential biaxial stretching method in which the film is stretched in the width direction, the longitudinal direction, and the width direction are stretched almost simultaneously. A simultaneous biaxial stretching method is preferred.

The stretching ratio of the biaxial stretching is 1.6 to 4.2 times, preferably 1.7 to 4.2 times in each direction.
It is 4.0 times. In this case, the stretching ratio in the longitudinal direction or the width direction may be increased, and may be the same. The stretching speed is preferably from 1000% / minute to 200,000% / minute, and the stretching temperature may be any temperature as long as it is equal to or higher than the glass transition temperature of the polyester and equal to or lower than the glass transition temperature + 100 ° C. 80-17
Stretching is preferably performed in the range of 0 ° C. Further, the film is subjected to a heat treatment after the biaxial stretching, and this heat treatment can be carried out by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature can be any temperature between 120 ° C. and 245 ° C., but is preferably between 120 and 240 ° C. Further, the heat treatment time can be arbitrarily set, but is preferably 1 to 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction.
Furthermore, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

The polyester has an average particle size of 0.0
Particles arbitrarily selected from known internal particles of 1 to 10 μm, external particles such as inorganic particles and / or organic particles can be contained. The use of particles having an average particle diameter of more than 10 μm tends to cause defects in the film, which is not preferable in terms of design.
Examples of such known particles include inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, and clay, and styrene, silicone, and acrylic acids. Organic particles and the like as constituent components can be used. Of these, inorganic particles such as dry, wet and dry colloidal silica and alumina, and organic particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituents are preferably used. Two or more of these internal particles, inorganic particles and / or organic particles may be used in combination as long as the properties are not impaired.

Further, the amount of these additives is 0.01% by weight or less.
Preferably it is in the range of 50% by weight. When the content is 0.01% by weight or less, winding of the film becomes difficult, which is not preferable in handling. On the other hand, if it exceeds 50% by weight, it is not preferable because it causes coarse projections and deterioration of film forming properties.

It is preferable to add known coloring pigments and coloring dyes to the film of the present invention according to the purpose of use in order to improve the design.

It is preferable to improve the adhesiveness by applying a corona discharge treatment or the like to the film surface in order to further improve the characteristics.

The film of the present invention may be coated with various coatings, and the coating compound, method, and thickness are not particularly limited as long as the effects of the present invention are not impaired.

The bonding polyester film of the present invention can be used by bonding it to metal, wood, paper, resin, or the like. More specifically, the film of the present invention can be preferably used by printing on a sheet of paper, resin, or the like and using a heat lamination or an adhesive.

Here, the resin is not particularly limited, but various thermoplastic resins and thermosetting resins can be used.

The metal is not particularly limited.
Metals made of iron or aluminum with good workability can be preferably used, and a known inorganic oxide coating layer or a metal plating layer may be further provided on the surface to improve adhesion or corrosion resistance. Good.

Before or after lamination, the polyester film for lamination of the present invention can be used after being subjected to various surface treatments such as embossing and printing. Also, the drawing-back characteristic after embossing, that is, 3
It is desirable to maintain the shape of the emboss even after 0 seconds.

Further, the polyester film for lamination of the present invention can be made of metal, paper,
It can be suitably used by bonding it to a member such as wood or resin, coating it, and forming it according to the purpose such as bending.

[0043]

The present invention will be described in detail with reference to the following examples. The characteristics were measured and evaluated by the following methods.

(1) Expansion and contraction curve at the time of temperature increase: A temperature increase rate of 10 ° C./TMA thermal analysis system EXSTAR6000 manufactured by Seiko Instruments Inc.
Min, measurement temperature range 30 to 300 ° C, sample measurement length 10
mm, the sample width was 4 mm, and the measurement was carried out under the condition of a load of an initial stress of 0.1 MPa. The longitudinal direction and the width direction of the film were measured, and the following T1 and T2 were confirmed from the expansion and contraction curves, and T2-T1 in each direction was calculated. Evaluation was performed based on this average value. T1 (° C.): The highest temperature at which the slope of the expansion / contraction curve changes from a negative value to a positive value at the time of temperature increase T2 (° C.): Temperature at which the elongation at the time of temperature increase reaches 25% A: T2-T1 is 15 ℃ or more. ：: T2−T1 is 8 ° C. or more and less than 15 ° C. X: T2-T1 is less than 8 ° C.

(2) Melting point (° C.) A 5 mg film was sampled and sampled, using a differential scanning calorimeter (RDC220) manufactured by Seiko Instruments Inc.
The measurement was performed at a heating rate of 10 ° C./min, and the peak temperature of melting was defined as the melting point. In particular, when a plurality of melting peaks appeared, the lower one was regarded as the melting point.

(3) Heat Shrinkage (%) In a gear oven heated to a temperature 50 ° C. lower than the melting point of each film, a film of 10 cm in length and 10 cm in width is shrunk for 3 minutes under no load, and The heat shrinkage rate (S = _SMD , _STD ) in the lateral direction was calculated by the following equation. S = 100 × (L ₀ −L) / (L ₀ ) where L ₀ : original length in the vertical or horizontal direction (cm), L: length after contraction in the vertical or horizontal direction (cm), and the following formula A , B were calculated and determined based on the following criteria. _{A = | S MD + S TD} | / 2 B = | S MD -S TD | ◎: A, B are both less than 5%. ：: Both A and B are 8% or less, and at least one of A and B exceeds 5%. X: At least one of A and B exceeds 8%.

(4) Embossing The polyester film was heated at 90 ° C. for 12 seconds and then heated at 180 ° C. for 3 seconds by a radiation heater. Immediately thereafter, embossing was performed using an embossing roll having a surface unevenness of 200 μm on the surface, and cooling was rapidly performed with a cooling roll at 30 ° C. The thickness of the film before and after embossing was measured with a thickness gauge having a contact area of 80 mm ² , and the emboss state was visually observed and touched, and judgment was made according to the following criteria. ：: The film thickness increased by 5 μm or more after embossing, and the embossed irregularities could be firmly confirmed visually and by touch. ：: Embossed irregularities can be easily confirmed visually and by touch. ×: Unevenness of emboss cannot be easily confirmed by visual inspection and touch.

Example 1 Polyethylene terephthalate (intrinsic viscosity: 0.65 dl /
g, melting point: 257 ° C., silicon oxide particles: particle size: 1.2 μm, concentration: 1% by weight) and polypropylene terephthalate (intrinsic viscosity: 1.02 dl / g, melting point: 222 ° C.)
Vacuum dried at 80 ° C. and 150 ° C. for 4 hours.

After drying, polyethylene terephthalate 80
Parts by weight and 20 parts by weight of polypropylene terephthalate were uniformly mixed and then supplied to a melt extruder. The polyester was extruded into a sheet form from a slit-shaped die, adhered to a mirror-surface cooling drum by electrostatic application (3.0 kV), and cooled and solidified to form an unstretched sheet. This unstretched sheet is first stretched 3.2 times in the longitudinal direction by a roll heated to a temperature of 85 ° C, and further stretched 3.3 times in the width direction at a stretching temperature of 100 ° C. 5% in direction
Was subjected to a heat treatment for 5 seconds to obtain a biaxially stretched polyester film having a thickness of 100 μm, that is, a polyester film for lamination of the present invention. The resulting film showed very good properties as shown in Table 1.

Example 2 In order to make the content of silicon oxide particles in the polyester mixture the same, the content in polyethylene terephthalate was set to 0.1.
A polyester film for lamination of the present invention was obtained in the same manner as in Example 1, except that the mixture ratio was 842% by weight and the mixing ratio of polyethylene terephthalate and polypropylene terephthalate was 95 parts by weight: 5 parts by weight. The resulting film exhibited excellent properties as shown in Table 1.

Example 3 Instead of polypropylene terephthalate, polybutylene terephthalate (PBT resin manufactured by Toray Industries, Inc .: type 11)
A polyester film for lamination of the present invention was obtained by the same method except that 00S) was used. The resulting film exhibited excellent properties as shown in Table 1.

Example 4 80 parts by weight of polyethylene terephthalate and polypropylene terephthalate 2 equivalent to those used in Example 1
0 parts by weight were vacuum dried at 180 ° C. and 150 ° C. for 4 hours, respectively.

After drying, these are charged into a polyester polymerization apparatus, and while maintaining the temperature at 290 ° C., the degree of vacuum is 5 to 10 Torr.
r for 30 minutes, and at a vacuum degree of 2 to 5 Torr for 30 minutes.
The mixture was stirred for minutes to prepare polyester pellets having an intrinsic viscosity of 0.70 dl / g.

The obtained polyester pellet was heated at 150 ° C.
After drying in vacuum for 4 hours, the mixture was supplied to a melt extruder, and a polyester film for lamination of the present invention was obtained in the same manner as in Example 1. The resulting film exhibited excellent properties as shown in Table 1.

Example 5 An A layer (thickness: 90 μm) was formed using the same mixture of polyethylene terephthalate and polypropylene terephthalate used in Example 1, and polyethylene terephthalate (intrinsic viscosity: 0.65 dl) was formed on both sides thereof. / G,
A layer B (thickness: 5 μm) was formed by composite extrusion using a melting point of 257 ° C., silicon oxide particles: particle diameter of 1.2 μm, concentration of 0.8% by weight. A film was formed under the same conditions as in Example 1 to obtain a polyester film for lamination of the present invention.
The resulting film exhibited excellent properties as shown in Table 1.

Comparative Example 1 Using polyethylene terephthalate (intrinsic viscosity: 0.65 dl / g, melting point: 257 ° C., silicon oxide particles: particle size: 1.2 μm, concentration: 0.8% by weight) dried in the same manner as in Example 1, Direction stretching temperature 90 ° C Width direction stretching temperature 10
A biaxially stretched polyester film having a thickness of 30 μm was obtained by the same method except that the temperature was changed to 5 ° C. The obtained film had poor properties as shown in Table 1.

Comparative Example 2 Biaxial having a thickness of 30 μm under the same conditions as Comparative Example 1 except that the stretching ratio was 3.7 times in the longitudinal direction, 3.9 times in the width direction, and the relaxation in the width direction was 2%. A stretched polyester film was obtained. The obtained film had very poor properties as shown in Table 1.

[Table 1]

According to the present invention, a polyester film for lamination excellent in embossing, bending and the like can be obtained.

[Brief description of the drawings]

FIG. 1 shows T1 and T2 of representative elongation curves.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA43 AA45 AA46 AF31Y AF61Y AF62Y AH03 BB08 BC01 4F100 AJ00B AK41A AK42 AL05A BA01 BA02 EJ381 GB07 HB00B JA03A JA20A JK08A YY00A

Claims (6)

[Claims] 1. A laminating polyester film, characterized in that T1 and T2 defined below in an expansion / contraction curve when a load of 0.1 MPa stress is applied and the temperature is raised satisfy (Equation 1). T1 (° C.): The highest temperature at which the slope of the expansion / contraction curve changes from a negative value to a positive value at the time of temperature rise T2 (° C.): Temperature at which elongation at the time of temperature rise reaches 25% T2−T1 ≧ 8 (° C.) ) (Equation 1) Wherein the longitudinal direction of the heat shrinkage factor when heated for 5 minutes at 50 ° C. lower than the melting point of the film S _MD (%), the thermal shrinkage ratio in the width direction S _TD (%) is the following (Equation 2) and (Equation 3)
The polyester film for lamination according to claim 1, which satisfies the following. | S _MD + S _TD | / 2 ≦ 8 (Equation 2) | S _MD −S _TD | ≦ 8 (Equation 3) 3. The method according to claim 1, wherein the plane orientation coefficient is 0.15 or less.
5. The polyester film for lamination according to any one of items 4 to 4. 4. The polyester film for lamination according to claim 1, wherein the polyester constituting the film has at least two kinds of polyesters. 5. The polyester according to claim 1, wherein the polyester constituting the film comprises a mixture of at least two polyesters of 5-99% by weight of polyethylene terephthalate and 1-95% by weight of polypropylene terephthalate. Polyester film for lamination. 6. The polyester film for lamination according to claim 1, which is used by being laminated to a decorative sheet or a decorative plate.