JPH0624775B2 - Leather-like thermoplastic polyester resin sheet and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a leather-like sheet made of a thermoplastic polyester resin (hereinafter, referred to as PAT) as a material, and a manufacturing method thereof. It is a thing.

(Prior Art) A leather-like sheet made of a synthetic resin is already known.
The leather-like synthetic resin sheet is generally called artificial leather. Conventional artificial leather has a base fabric layer made of fiber,
In many cases, a foamed synthetic resin surface layer was attached to integrate the two.

The reason why the base fabric layer is required is that the foamed resin layer alone cannot provide the properties required for leather, particularly the tensile strength. Since the conventional artificial leather uses the base cloth layer, there is a problem that the base cloth layer and the resin layer are separated from each other and the manufacturing process is complicated. Therefore, if possible, it was desired to make artificial leather with a single layer.

The synthetic resins that have been used to make artificial leather have been mostly polyvinyl chloride resins and polyurethane resins. This is because these resins have appropriate flexibility and are easy to foam. others,
Polyamide resin was also considered to be usable, but it has not been widely used as artificial leather because it is difficult to foam. Other resins have not been used in the production of artificial leather because they were considered unsuitable for producing artificial leather from the beginning or were difficult to foam.

On the other hand, PAT was used in the production of artificial leather by once making it into fibers and then interlacing the fibers to use it as a base fabric layer. However, PAT has never been used as a resin layer of artificial leather. This is because it is difficult for PAT to foam. More specifically, the reason is PA
Since T is hard and poor in flexibility and is crystalline, it has the property of rapidly changing from a solid to a liquid with low viscosity when heated, so the temperature range where the viscosity is suitable for foaming is narrow, and therefore foaming This is because it is difficult to control the temperature at that time, and since the gas that is the driving force for foaming is immediately released, it is difficult to foam.

However, it is known that when PAT containing a foaming agent is extruded into the atmosphere from an extruder, it foams at a low magnification. The expansion ratio is usually 2 times or less, and if it is extruded into a sheet shape, it can be expanded relatively large,
Still, the expansion ratio is about 4 times. Therefore, an attempt was made to expand the foam further.

Japanese Patent Laid-Open No. 55-2045 discloses a PAT containing a foaming agent.
Is extruded into a depressurized region to foam at a high magnification. In this publication, it is reported that a foam having a circular cross section that is foamed 22 times to 32 times is obtained. However, this method has the drawback that it is difficult to construct the decompression region. In particular, it is difficult to carry out this method when making artificial leather. The reason is that when PAT is extruded in a sheet form, the extruded sheet has irregularities on the surface or is greatly deformed due to foaming, so that an irregular shape is continuously passed. This is because it is not easy to form such a decompression region, and it is difficult to provide a sufficient decompression seal particularly for a sheet-shaped object.

On the other hand, it is known that when a foam plate made of styrene resin is bent, it becomes highly flexible. It is described in JP-B-63-60705. However, since this publication limits the resin to styrene resin, it does not teach anything about the foam plate of PAT, and the flexible foam plate obtained in this way has a cushioning material, a heat insulating material, or a filling material. I only teach that it will be suitable for bending and use, but it does not teach that it will be suitable for leather.

(Problems to be Solved by the Invention) The present invention has been made in order to provide a sheet having properties which are inevitable to leather only by a sheet obtained by foaming a synthetic resin.

(Means for Solving the Problem) This inventor has generally considered that it is difficult to foam a PA.
I tried to foam T to make artificial leather. Therefore, the present inventor tried to extrude PAT into the atmosphere to cause it to foam. As a result, it was found that when PAT was extruded under appropriate conditions, a sheet having a foaming ratio of about 4 was obtained. Further, the present inventor has found that when the obtained foamed sheet is brought into contact with steam or the like to heat the sheet, the sheet is further swollen and becomes a sheet which is evenly and finely foamed at a high magnification.

Further, the inventor of the present invention compresses the thus obtained uniform and finely foamed PAT sheet by sandwiching it between rolls at room temperature to increase the flexibility of the sheet, whereby a leather-like flexible and tough sheet can be obtained. I found that. Further, the present inventor has confirmed that a leather-like sheet can be similarly obtained by bending or rubbing the sheet instead of sandwiching the sheet between rolls and compressing the sheet.

The inventor also sought the structure of the leather-like sheet obtained as described above. As a result, the leather-like sheet
It was confirmed that the foam was uniformly and finely foamed, the cell wall was in a special state, and the entire sheet had a peculiar flexibility. Here, being uniformly and finely foamed means that the bubbles are small with a diameter of substantially 1 mm or less, and the bubble wall has a small thickness of 100 microns or less. I mean. Further, the fact that the bubble wall is in a special state means that at least a part of the bubble wall extends while being bent irregularly. In addition, the fact that the entire sheet has a peculiar degree of flexibility means that the Gurley type flexibility test indicates that the degree of flexibility is 20
It means having a small value of 000 mg or less. The present invention was made on the basis of the findings described above.

(Summary of Invention) This application includes two kinds of inventions, an invention of a product and an invention of a manufacturing method. The invention of the product is intended for a leather-like PAT sheet, and the invention of the manufacturing method is a leather-like PAT sheet.
The present invention relates to a method for manufacturing an AT sheet.

The leather-like PAT sheet has fine bubbles having a diameter of substantially 1 mm or less, and the bubble walls have a thickness of 100 μm or less and are uniformly and finely foamed. It is characterized in that it is bent in a regular manner and extends, and the flexibility as a sheet is 20000 mg or less in a Gurley test.

In addition, the method for producing a leather-like PAT sheet uses the above-mentioned uniformly and finely foamed sheet, and applies a compressing or bending force to this foamed sheet to bend the cell walls of each cell irregularly in the extending direction. The method is characterized by:

(Explanation of Constituent Requirements of the Invention) PAT that can be used in the present invention is a high molecular weight chain polyester obtained by reacting an aromatic dicarboxylic acid with a dihydric alcohol. Although terephthalic acid is most often used as the dicarboxylic acid, isophthalic acid or 2,6-naphthalenedicarboxylic acid may be used. In addition, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, and diphenoxy dicarboxylic acid may be used. On the other hand, ethylene glycol is mainly used as the dihydric alcohol, but trimethylene glycol, tetramethylene glycol, neopentylene glycol, hexamethylene glycol, cyclohexane dimethylol, tricyclodecane dimethylol, 2,2-bis (4 There are also those using -β-hydroxyethoxyphenyl) propane, 4,4'-bis (β-hydroxyethoxy) diphenyl sulfone and diethylene glycol. Such PAT is commercially available. In the present invention, commercially available PAT can be used.

Among the above-mentioned PATs, those suitable for use in the present invention include polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate elastomer,
Examples include amorphous polyester and polycyclohexane terephthalate. These resins can be used alone or in combination. Further, a resin other than PAT can be mixed and used with these resins. If another resin is mixed, the amount of the other resin needs to be smaller than that of PAT.

The leather-like sheet must be uniformly and finely foamed. This can be defined by the bubble size, bubble wall thickness, sheet density, and the like. The bubble size is substantially less than 1 mm, preferably less than 500 microns. Here, "substantially 1 mm or less" means that most of the bubbles have a size of 1 mm or less, and does not mean that bubbles having a size of 1 mm or more should never be applied. Absent. The thickness of the bubble wall is similar, and the thickness of the bubble wall is substantially 100 μm or less, preferably 50 μm or less, more preferably 20 μm or less. In addition, the size of the bubble is generally larger than the thickness of the bubble wall. Density is 1.1g / cc or less, preferably 0.8g / cc
cc or less, more preferably 0.15 to 0.5 g / cc.

A great feature of the leather-like sheet according to the present invention is that the cell walls are curved and extend irregularly. This is clearer when viewed in an enlarged scale. FIG. 1 is an enlarged view of the leather-like sheet according to the present invention cut in the thickness direction. In FIG. 1, 1, 2, 3 ...
... indicates one bubble, 11, 12, 13 ...
... indicates a bubble wall that divides each bubble. Each of the bubble walls 11, 12, 13 ... Is bent with various amplitudes varying in size up to several times its thickness. Some of the bends are sharp as if the paper were folded back, and some are made up of many wrinkles, such as when the paper is crushed and squeezed into pieces by hand. . The bubble wall is torn in places, causing cracks.

On the other hand, the conventional foamed sheet has an enlarged cross section in the thickness direction as shown in FIG. In FIG. 2, reference numerals 21, 22, 23, ... Are all one bubble, and 31, 32, 33, ... Are bubble walls that define each bubble. The bubble walls 31, 32, 33 are curved to some extent. The curvature is such that, between two adjacent specific bubbles, the bubble wall that separates them is always concave or convex in one bubble, and concave and convex are intermingled. It hardly happens. So
In the conventional foamed sheet, the cell wall does not bend irregularly. Further, even in the conventional foamed sheet, cracks may occur in the cell walls, but the cracks are much smaller than in the leather-like sheet according to the present invention. Thus, the leather-like sheet according to the present invention is completely different from the conventional one in that the cell walls are irregularly bent.

Further, the leather-like sheet according to the present invention also differs from the conventional PAT foam sheet in terms of flexibility. For example, in a polyethylene terephthalate sheet obtained by foaming butane as a foaming agent, a normal PAT foam sheet having a basis weight of 400 g / m ² , a thickness of 1.50 mm and a density of 0.27 g / cc has a softness Is measured by a Gurley type flexibility test, and shows a flexibility of 48326 mg. In contrast, the leather-like sheet according to the present invention made from this ordinary PAT foam sheet has a basis weight of 397 g / m ² , a thickness of 1.29 mm, and a density of 0.
The 31 g / cc leather-like sheet exhibits a flexibility of 16751 mg. Furthermore, when the same test is performed on various PAT sheets, the conventional PAT foam sheet has a flexibility of 40,000 mg.
In contrast to the above, it was confirmed that the leather-like sheet according to the present invention has a flexibility of 20000 mg or less. Therefore,
The leather-like PAT foam sheet according to the present invention is unique in that it has a Gurley type softness of 20000 mg or less.

The Gurley-type flexibility test method will be described below. A test piece with a length of 1 cm and a width of dcm is made up of 5 pieces each, and a Gurley-type tester as shown in FIG. 7 is used to attach the test piece to the chuck. Fix the chuck according to. Then, in the load mounting holes a, b, c below the fulcrum of the pendulum,
Scale RG when the test piece separates from the pendulum by applying a suitable load Wa (g), Wb (g), Wc (g) to rotate the movable arm at a constant speed.
Then, the bending resistance is calculated from the following equation, and the bending resistance is expressed by an average value for each of the five front and back surfaces.

Here, a, b, and c represent the distance (cm) between the load mounting hole and the fulcrum.

In addition, the PAT foam sheet according to the present invention is an ordinary PA.
It shows a unique elongation curve as compared to the T foam sheet. For example,
The above-mentioned ordinary PAT foam sheet with a basis weight of 400 g /
The polyethylene terephthalate foam sheet having m ² , thickness of 1.50 mm and density of 0.27 g / cc shows the relationship between tension and elongation as shown by the broken line A in FIG. The leather-like PAT foam sheet according to
It has g / m ² , thickness of 1.29 mm and density of 0.31 g / cc, and shows the relationship between tension and elongation as shown by the one-dot chain line B in FIG. That is, the leather-like sheet according to the present invention has an elongation that increases in proportion to the tension while a tension of about 20 kg / cm ² or less is applied, and an elongation of about 50% has already been obtained at a tension of about 32 kg / cm ^2. Show. On the other hand, the above-mentioned ordinary P
The AT foam sheet has an elongation of 5% or less and hardly expands even when a force of up to about 50 kg / cm ² is applied.
When a force of 0 kg / cm ² is applied, it suddenly reaches 100
It shows a high elongation of more than%. As described above, the leather-like PAT foam sheet according to the present invention is unique in that it exhibits a large elongation of several percent to several percent by a small tension of about 30 kg / cm ² .

Next, a method for manufacturing the leather-like PAT foam sheet according to the present invention will be described. The manufacturing method is as described above.
A uniform and finely foamed sheet made of PAT, which is made of a foamed sheet having a bubble with a diameter of substantially 1 mm or less and a bubble wall having a thickness of substantially 100 μm or less. The method is characterized in that a compressive or bending force is applied to the foamed sheet at the following temperature to bend the cell wall in a wavy shape to extend it.

The foamed sheet used as a material in this manufacturing method may be manufactured by any manufacturing method. For example, in accordance with the teaching of the above-mentioned JP-A-55-2045, if a PAT sheet foamed in a reduced pressure region to obtain a uniformly and finely foamed PAT sheet can be used as a material. However, the preferred method is foaming over two times, as described below.

The method of performing foaming over two times is as follows. A high-temperature PAT containing a foaming agent is extruded into a sheet shape and immediately cooled immediately to form a primary foamed sheet, and then the primary foamed sheet is heated to 60 ° C. or more for further foaming. And a secondary foamed sheet is obtained. In order to extrude the PAT, as has been done so far, the PAT was put into an extruder and melted, and a foaming agent was pressed in and kneaded from the middle of the extruder, and this kneaded product was attached to the extruder. It may be formed by molding the die into a sheet. When the sheet is extruded from the die, the cross-sectional shape of the sheet may be annular or linear.
In the case of an annular shape, it is cut open later to make a flat sheet.

The reason why the sheet immediately after being extruded is rapidly cooled is to set the crystallinity of the primary foam sheet to a low value of 30% or less.
The temperature for quenching is set to the glass transition point of PAT or lower.

In the present invention, the secondary foamed sheet thus obtained has uniform and fine cells of substantially 1 mm or less, and the cell walls constituting the cells are thin and substantially 100 microns or less. Taking advantage of foaming, PA
At a temperature not higher than the glass transition point of T, the secondary foamed sheet is compressed or bent, whereby the cell walls are irregularly bent.

Various methods can be used to compress or bend the uniformly and finely foamed PAT sheet. For example, for compression, the compression direction may be the thickness direction, the length direction, or the width direction of the sheet. However, it is easy to compress in the thickness direction. In the compression in the thickness direction, the sheet may be partially compressed or entirely compressed,
Preference is given to partial compression. Also, PA
In order to bend the T-foamed sheet, the bending direction may be any direction, but the length direction and the width direction are preferable, and the length direction is preferable among them. Also,
It is desirable that the compression or bending be done in an appropriate combination rather than simply doing one of them.

A preferred method as an industrial method is a method in which the PAT foam sheet is passed through a large number of rolls and combined with compression or bending to continuously perform the compression. For example, the sheet surface is partially compressed by passing it through an embossing roll with unevenness, or the sheet is partially compressed in the thickness direction by passing between a number of pairs of rolls, and the length direction is Also stretch or slacken young, or pass through a zigzag between multiple rolls to bend the sheet in the longitudinal direction,
It is a method of stretching in the length direction or slackening young.

The above-mentioned compression or bending needs to be performed in a state where the PAT foam sheet is below the glass transition point of PAT. The glass transition point of PAT varies depending on the types of the dicarboxylic acid and dihydric alcohol constituting PAT, but roughly speaking, it is within the range of 30 to 90 ° C. Therefore,
Usually, the PAT foam is compressed or bent at a temperature of 60 ° C or lower.

Since PAT is a resin that is easily hydrolyzed at high temperatures, it is desirable to dry it in advance when it is extruded from an extruder and foamed. For drying, for example, a dehumidifying dryer may be used. In that case, the drying condition is, for example, that air having a dew point of −30 ° C. is heated to 160 ° C. and PAT is exposed to this air for about 4 hours.

Various foaming agents can be used. Broadly speaking, any of a solid compound that decomposes to generate gas at a temperature above the softening point of PAT, a liquid that vaporizes in PAT when heated, an inert gas that can be dissolved in PAT under pressure, etc. Can also be used. The above-mentioned solid compound is, for example, azodicarbonamide, dinitrosopentamethylenetetramine, hydrazocarbonamide, sodium bicarbonate and the like. Liquids that vaporize in PAT include saturated aliphatic hydrocarbons such as hexane, pentane and butane, saturated alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene and xylene, methylene chloride and Freon (registered). Halogenated hydrocarbons such as Trademark). The inert gas is, for example, carbon dioxide or nitrogen. In addition, as a foaming agent, JP-A-50-13
High molecular weight chain aromatic polycarbonates can also be used, as taught in the 5237 publication.

When the softened PAT containing the foaming agent is extruded from the die, the PAT foams. This foaming is the primary foaming in the present invention, and the obtained foam is a primary foaming sheet. The primary foam sheet stays at a low expansion ratio,
It usually has a high density. The expansion ratio varies depending on the shape of the foam, but is about 5 times at most. In the present invention, the primary foam sheet thus obtained is rapidly cooled to a temperature below the glass transition temperature of PAT immediately after being produced and while it is still at a high temperature.

When the primary foamed sheet is rapidly cooled, it does not become a crystal and solidifies, so that the crystallinity becomes low. Crystallinity depends on the degree of quenching. For example, it differs depending on the type of cooling medium, the temperature of the cooling medium, the contact state with the cooling medium, and the like. When the primary foamed sheet produced by extrusion is directly contacted with water at room temperature and cooled, the crystallinity of the primary foamed sheet becomes several percent to ten percent, usually 30% or less. . However, when the primary foamed sheet made by extrusion is guided to a mold to shape it, unless the mold is forcibly cooled, the foamed sheet is not rapidly cooled, so that the crystallinity is 30% or more. Becomes Particularly, thick primary foam sheets have a crystallinity of 3
It becomes 0% or more. Therefore, when the primary foamed sheet is produced by the extruder, the primary foamed sheet is advanced along the mold forcibly cooled and rapidly cooled.

In order to effectively quench the primary foamed sheet, it is desirable to make the thickness of the primary foamed sheet as small as possible so that the primary foamed sheet has a large surface area as compared with its volume. That is, it is desirable that the width be made as large as possible and the thickness be made thin so that the thickness is 10 mm or less, particularly 3 mm or less. In that case, when the sheet is made cylindrical, a mandrel is provided inside the cylinder so that the sheet can be advanced along the mandrel, and the mandrel is cooled by water, and the length of the mandrel is made as long as possible. On the other hand, when the sheet is flat, the sheet is sandwiched between the pair of rolls so that the sheet advances while being cooled, and the roll is cooled with water, and the diameter of the roll is increased as much as possible. Thus, the crystallinity of the primary foam sheet is suppressed to 30% or less.

Generally, the crystallinity of a resin can be measured by a density, an X-ray diffraction image, a nuclear magnetic resonance absorption spectrum, or the like. However, since the resin foam sheet contains air bubbles therein, these The crystallinity cannot be measured by the method. Therefore, the primary foam sheet of PAT must be subjected to a thermal method such as measuring the heat of fusion and the heat of cold crystallization. The principle is that when a PAT foam sheet is heated at a constant speed, crystals first grow and then melt, but when the crystals grow, heat is generated and the heat of fusion is absorbed, so this property is utilized. To do.
Specifically, the amount of cold crystallization heat generated during crystallization and the amount of heat of fusion absorbed during melting were measured, and this was compared with the amount of heat of fusion indicated by a perfect crystal standard to determine the degree of crystallinity. calculate.

In order to actually measure the heat of cold crystallization and the heat of fusion of the PAT foam, it is desirable to use the differential scanning calorimetry method. In the differential scanning calorimetry method, the heaters of the measurement material and the standard product operate independently, and when a temperature difference occurs between the two during the process of constant speed heating, either heat flow increase or suppression mechanism automatically operates. Since it cancels this out, this heat flow velocity difference is directly recorded. The crystallinity is theoretically calculated according to the following formula.

(Amount of heat of fusion per mole-Amount of heat of cold crystallization per mole) ÷ Amount of heat of fusion per mole of completely crystalline PAT x 100 = Crystallinity (%) Here, the amount of heat of fusion per mole of completely crystalline PAT is the polymer According to Data Handbook (published by Baifukan), 26.9KJ
Since it is said that it will be used.

In this invention, a PAT primary foam sheet having a crystallinity of 30% or less is used for the second foaming. This is secondary foaming. At the time of secondary foaming, this is heated to 60 ° C. or higher. The heating means is not particularly limited. Whether heating by conduction, heating by radiation, or convection,
Both can be used even by heating with high-frequency power. Any heating medium can be used as long as it does not invade the PAT. Among them, a preferable heating method is a method in which the primary foam of PAT is brought into contact with heated metal or air, or brought into contact with steam or heated water to heat.

The heating time at the time of secondary foaming is appropriately determined according to the properties and shape of PAT, the type and temperature of the heating medium. In general,
When the temperature of the heating medium is low, the heating time is lengthened, and conversely, when the temperature is high, the heating time is shortened. Also,
When the thickness of the foam is large, the heating time is lengthened, and conversely, when the thickness is small, the heating time is shortened.

When the primary foam is heated by contacting it with a metal plate, the metal plate is preferably kept at a temperature of 60 to 200 ° C. for 5 seconds or more. When the primary foam is heated by contacting it with air, the primary foam is placed in an oven and the internal temperature of the oven is set to 100-230 ° C. for 10 seconds-5.
It is desirable to heat for a minute. In the case of heating with a metal plate or air, it is desirable to avoid performing secondary foaming immediately after primary foaming, and leave it for at least 24 hours after primary foaming, usually for about 3 days, before secondary foaming.

On the other hand, when the primary foam is heated by contacting it with steam or heated water, secondary foaming can be performed immediately after primary foaming. In this case, steam or water is 60 ℃
The temperature is −125 ° C., and the contact time is 10 seconds-10 minutes. Steam or water exceeding 125 ° C may decompose the primary foam, so it is better to avoid using it.

Various modes can be taken to bring the PAT foam into contact with steam or water. As shown in FIG. 4, the foam may be immersed in heated water. Further, as shown in FIG. 5, a wire net may be placed above the surface of heated water, a foam may be placed on the wire net, and the foam may be contacted with water vapor evaporating from the water. Further, as shown in FIG. 6, pressurized steam may be blown into the container containing the foam.

When heating the foam by contacting it with water or steam, it is desirable to put the foam into a mold and mold it into a desired shape.
When using the mold, water or steam enters the mold,
Make direct contact with the foam.

In this way, when the PAT foam is brought into contact with water or steam having a temperature of 60 ° C. or higher and heated, the PAT foam largely undergoes secondary foaming and becomes a low-density foam. In general, heating with water or steam is larger than air heating, and secondary foaming is more likely to occur. With water or steam, the secondary expansion ratio is 1.3 times at the smallest, and 4 times or more when the secondary expansion is large.
Moreover, foaming can be performed uniformly, and the obtained secondary foam has fine and uniform cells. Thus, a good quality low density foam can be obtained.

In practicing this invention, various additives can be included in the PAT. For example, a small amount of talc powder, an antistatic agent, a pigment, a flame retardant may be added as a cell regulator, or an acid dianhydride such as pyromellitic dianhydride or diglycidyl terephthalate may be added to improve the melting characteristics of PAT. 0.5 to 5% by weight of an epoxy compound or a metal oxide of Group Ia or IIa of the periodic table or sodium carbonate,
It can be added alone or as a mixture.

Further, when the method of the present invention is carried out, the obtained secondary foam is kept at a high temperature, for example, 200 ° C. or higher to enhance the crystallinity of PAT, and thereby the secondary foam having further improved heat resistance. You can also get a body.

The secondary foamed sheet thus obtained is compressed or bent as described above to obtain a leather-like PAT foamed sheet.

Further, by rubbing the surface of the sheet obtained by the above method with sandpaper, a brush, a file, etc.,
It can also be made into a backskin-like leather-like sheet.

(Effect of the Invention) According to the present invention, the leather-like PAT foam sheet is uniformly and finely foamed, and has bubbles with a diameter of substantially 1 mm or less,
Since the cell walls have a thickness of substantially 100 μm or less, they have the appearance of natural leather. Moreover, in the case of a foamed sheet made of PAT, the cell walls constituting each cell are bent and extend irregularly, and the flexibility as a sheet is 20,000 mg or less in the Gurley test. It also has the strength and feel of natural leather. On top of that, this leather-like sheet
Since it is made of PAT only, it has the feature of being easy to manufacture. Therefore, the leather-like sheet according to the present invention is expected to have wide applications as an alternative to natural leather. In this respect, the present invention greatly benefits.

Further, according to the present invention, there is provided a uniformly and finely foamed sheet of PAT, which has a bubble having a diameter of substantially 1 mm or less and a bubble wall having a thickness of substantially 100 μm or less. As a material, by applying a compressing or bending force to the foamed sheet at a temperature below the glass transition point of PAT, the cell wall can be easily bent irregularly, which results in a leather-like PAT. A foam sheet can be easily made. Therefore, the leather-like sheet can be continuously and easily supplied at low cost. In this respect, the manufacturing method according to the present invention greatly benefits.

Furthermore, according to the method of the present invention, a PAT containing a foaming agent is used.
Is extruded to form a foamed sheet, and the foamed sheet at a high temperature immediately after being extruded is rapidly cooled below the glass transition point of PAT to form a primary foam having a PAT crystallinity of 30% or less. The foamed sheet has a low degree of crystallinity, and accordingly, it is easy to heat the foamed sheet again to foam it.
Since such a primary foamed sheet is heated to 60 ° C. or higher to be foamed to form a secondary foamed sheet, the secondary foamed sheet is well foamed at a high magnification. Therefore, the secondary foamed sheet is uniformly and finely foamed, has bubbles having a diameter of substantially 1 mm or less, and has a bubble wall having a thickness of substantially 100 microns or less. Using such a secondary foamed sheet as a material, a compression or bending force is applied to the foamed sheet at a temperature not higher than the glass transition point of PAT, so that a leather-like sheet can be easily produced as described above. Therefore, the leather-like sheet can be continuously and easily supplied at low cost. In this respect, the manufacturing method according to the present invention greatly benefits.

Next, the reason why the present invention is excellent will be specifically described with reference to Examples and Comparative Examples. In the following, simply "parts" means "parts by weight".

Example 1 (Production of Primary Foamed Sheet) Polyethylene terephthalate as PAT (manufactured by Teijin Ltd.,
The following compositions were made using the trade name TR8580).

PAT 100 parts Talc 0.6 parts Pyromellitic anhydride 0.3 parts Sodium carbonate 0.1 parts The above composition was put into an extruder of 60 mmΦ, the temperature of the feeding part of the extruder was 280 ° C., the temperature of the compression part was 285 ° C.,
The temperature of the melting part and the temperature of the head part are both 275 ° C., the temperature of the mold is 270 ° C., and the screw rotation speed is 25.
rpm. Further, butane as a foaming agent was pressed in at a ratio of 1.3 parts from the middle of the extruder and extruded. Use a ring-shaped mouthpiece with a diameter of 60 mm and a slit width of 0.4 mm.
And In addition, a plug having a diameter of 205 mmΦ and a length of 740 mm was provided at the tip of the die, and this was quenched with water at 25 ° C. The foamed sheet thus obtained was cut open to form a flat sheet, which was once wound into a roll and used as a primary foamed sheet. The primary foam sheet has a basis weight of 400 g /
m ² , thickness 1.50 mm, density 0.27 g / cc, average bubble size 320 microns, average bubble wall thickness about 3
It was 0 micron. The crystallinity of the primary foam sheet was 8%.

(Production of Secondary Foamed Sheet) After that, the primary foamed sheet was brought into contact with steam at 100 ° C. for 5 minutes for further foaming, and this was left at room temperature and cooled to obtain a secondary foamed sheet. The secondary foam sheet had a basis weight of 400 g / m ² , a thickness of 5.6 mm, a density of 0.07 g / cc, an average cell size of 560 μm, and an average cell wall thickness of about 20 μm. .

(Treatment of Secondary Foamed Sheet) In order to make the secondary foamed sheet obtained above flexible, it was compressed by an embossing roll at room temperature of 25 ° C. As the embossing roll, the ones having a diameter of 14 cm are paired to face each other,
The gap between the rolls was 0.3 mm. The width of the roll surface is
Grooves having a depth of 0.2 mm and a depth of 0.5 mm were provided at intervals of 1 mm in both the axial direction and the circumferential direction of the roll. The rotation speed of the roll is 3 rpm, and the secondary foam sheet is
I passed it only once.

The secondary foamed sheet thus compressed was a good leather-like sheet. The physical properties of the leather-like sheet are measured to have a basis weight of 404 g / m ² , a thickness of 1.56 mm and a density of 0.25 g / cc.
The maximum tensile strength is 4.90 kg / cm, and the tensile elongation at break is 39.
6%, maximum tear strength 1.12kg, flexibility 12118mg
Met.

Example 2 In this example, the primary foamed sheet obtained in Example 1 was immersed in boiling water for secondary foaming, and the obtained secondary foamed sheet was compressed with a roll having a smooth surface to form a leather-like sheet. And The details are as follows.

(Production of Secondary Foamed Sheet) The primary foamed sheet was immersed in boiling water for 2 minutes for secondary foaming, and this was left at room temperature and cooled to obtain a secondary foamed sheet. The secondary foam sheet has a basis weight of 400 g / m ² and a thickness of 5.2 m.
m, the density was 0.07 g / cc, the average cell size was 560 μm, and the average cell wall thickness was about 20 μm.

(Treatment of Secondary Foamed Sheet) In order to make the secondary foamed sheet obtained above flexible, it was compressed by a roll at room temperature. The roll has a diameter of 1
Use a 4 cm smooth surface with a roll gap of 0.3 m
m and made them face each other. The roll was rotated at a speed of 3 rpm, during which the secondary foam sheet was passed only once. The resulting foamed sheet has small wrinkle-shaped irregularities formed on the surface,
It had a leather-like appearance. The leather-like sheet obtained is
The basis weight was 404 g / m ² , the thickness was 1.43 mm, the density was 0.28 g / cc, and the flexibility was 12296 mg.

Example 3 In this example, the secondary foam sheet obtained in Example 1 was pressed to obtain a leather-like sheet. The details are as follows.

Room temperature of 25 ° C to make the secondary foam sheet flexible
Then, the secondary foamed sheet was sandwiched between aluminum plates and compressed by a press. As the aluminum plate, used was one in which grooves having a depth of 0.5 mm were irregularly carved in various directions on a smooth surface of 30 cm square. The press applies a pressure of 250 kg / cm ² to 10
It was added for 2 seconds. The resulting foamed sheet looks like leather and has a basis weight of 404 g / m ² , a thickness of 2.07 mm and a density of 0.20.
The g / cc and flexibility were 11672 mg.

Example 4 This example is an example of repeatedly compressing a foam sheet. The details are as follows.

The secondary foamed sheet obtained in Example 1 was passed through the embossing roll used in Example 1 twice. The rotation speed of the roll at that time was also 3 rpm. The leather-like sheet obtained was more flexible. The obtained leather-like sheet has a basis weight of 404 g / m ² , a thickness of 1.41 mm and a density of 0.28 g.
/ cc, the flexibility was 10893 mg.

Example 5 In this example, the surface of the leather-like sheet obtained in Example 1 was rubbed with sandpaper to obtain a backskin-like sheet. The details are as follows.

As the sandpaper, # 400 was used. Sandpaper was applied to the surface of the leather-like sheet obtained in Example 1 and pressed, and the surface of the sheet was rubbed with the sandpaper 6 times. Then, the surface of the leather-like sheet became backskin-like. The backskin-like sheet obtained had a basis weight of 404 g / m ² , a thickness of 1.56 mm, a density of 0.25 g / cc, and a flexibility of 11472 mg.

Example 6 In this example, after the secondary foamed sheet obtained in Example 1 was passed through an embossing roll, the secondary foamed sheet was kneaded. The details are as follows.

The secondary foamed sheet obtained in Example 1 was passed once through the embossing roll used in Example 1. 30x thus obtained
Fold a 30cm leather-like sheet in two, sandwich it between two aluminum plates, fix both ends of the sheet to the surface of each aluminum plate with an adhesive, put the aluminum plate horizontally and put 5kg of it on it. A weight was placed, the upper aluminum plate was reciprocated 6 times in 1 minute, and a total of 30 times was reciprocated to rub the sheet.

The obtained sheet was a highly flexible leather-like sheet having a basis weight of 404 g / m ² , a thickness of 1.05 mm and a density of 0.24 / c.
c, the flexibility was 8862 mg.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of the leather-like thermoplastic polyester resin sheet according to the present invention cut in the thickness direction. FIG. 2 is an enlarged cross-sectional view of a conventional thermoplastic polyester resin sheet cut in the thickness direction. FIG. 3 is a graph comparing the elongations of the leather-like thermoplastic polyester resin sheet according to the present invention and the conventional resin sheet. 4 to 6 show, in the direction of the present invention,
It is a model figure showing various modes at the time of carrying out secondary foaming. FIG. 7 shows the flexibility test method in the present invention.

Claims (3)

[Claims] 1. A uniformly and finely foamed sheet made of a thermoplastic polyester resin, which has bubbles with a diameter of substantially 1 mm or less, and a bubble wall having a thickness of substantially 100 μm or less, Moreover, the leather-like thermoplastic polyester resin sheet is characterized in that the cell walls constituting each cell are bent and extend irregularly, and the flexibility as a sheet is 20,000 mg or less in the Gurley test. 2. A uniformly and finely foamed sheet made of a thermoplastic polyester resin, which has bubbles having a diameter of substantially 1 mm or less and a bubble wall having a thickness of substantially 100 μm or less. And a compressive or bending force is applied to the foamed sheet to make the cell walls forming each cell irregularly bent and extended, a leather-like thermoplastic polyester-based resin sheet Manufacturing method. 3. A thermoplastic polyester-based resin containing a foaming agent is extruded to form a foamed sheet, and the foamed sheet at a high temperature immediately after being extruded is rapidly cooled below the glass transition point of the resin to crystallize the resin. The degree of chemical conversion is 30% or less as a primary foamed sheet, the primary foamed sheet is heated to 60 ° C. or more to foam into a secondary foamed sheet, and then compressed to a secondary foamed sheet at a temperature not higher than the glass transition point of the resin, or A method for producing a leather-like thermoplastic polyester-based resin sheet, which comprises applying a bending force to make the cell walls constituting each cell irregularly bent and extended.