JPS62259848A - Synthetic paper having double layer structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The synthetic paper of the present invention is used as poster paper, support for image-receiving sheets for thermal transfer recording, bag-forming paper material, writing paper, computer home paper, and the like.

The synthetic paper of the present invention can be used particularly as a support for image-receiving sheets for thermal transfer recording, and especially as a support for color copying used in video printers and the like that form characters and images on a receptor using a T signal such as a thermal head. Useful.

[Prior art]

Conventionally, a transfer sheet having a transfer layer containing a sublimable or vaporizable dye is placed on top of a receiving sheet, and the transfer sheet is heated to sublimate or vaporize the dye contained in the transfer layer and dye the receiving sheet. Thermal transfer is known to produce a dye image on a receiving sheet.

Specifically, in a transfer type thermal recording method using a heat source controlled by a hypochondrium signal such as a thermal head, as shown in FIG. 11 and a support 12 are placed on a drum 3.
and a heat source 4, and a color copy is obtained by transferring the coloring material of the layer 22 onto the +i image receiving layer 11 in response to a signal.

The content of the image-receiving layer 11 varies depending on the content of the coloring material used; in the case of a heat-melting type coloring material containing a pigment, the support 12 itself may be used, and in the case of a sublimable basic dye type coloring material, (d Activated clay (activated clay) 1 is made of a polymeric material such as polyester in the case of a sublimable disperse dye type coloring material.In the case of a conventional receptor, it is made of a polymeric material such as polyester. Therefore, the surface of the image-receiving layer 11 had irregularities of 5 to 15 μm, and undulations of 10 to 20 μm per duck.

Even surface treatment using a supercalender can only improve the unevenness or undulations to a certain extent. For this reason, when the coloring material is transferred from the coloring material layer 22, the surface unevenness of the image receiving layer 11 is 3 to 5 μm or more, or the waviness is 1 μm or more.
■At 910 μm or more, not only heat-melting coloring materials but also sublimation coloring materials cannot be accurately transferred according to the image signal, resulting in missing dots and missing dots in 1 m2 of images! causing quality disturbances,
It gave a rough texture to the midtones (-!? 1986-2
No. 14696).

In addition, as the support 12, paper or inorganic fine powder can be used for
Synthetic paper made of stretched film of thermoplastic resin containing 50% by weight (#f Publication No. 46-40794), transparent polyethylene terephthalate film, or transparent film with silica or carbonate on the surface to increase whiteness and dyeability. Vn synthetic paper or the like whose surface is coated with an inorganic compound such as calcium and a binder is used.

[Problems with conventional technology]

Considering the after-use of the heat-transferred receptor sheet (copying, pencil writing, storage stability, etc.), synthetic paper is recommended as the image-receiving sheet for thermal transfer recording in terms of strength, dimensional stability, and dust-free property. or plastic film is preferred.

However, although transparent plastic films have good copyability, they have low opacity, lack hiding properties, and have poor image contrast, making them difficult to read.

Therefore, synthetic paper with a high opacity of 80% or more, or coated synthetic paper with an image-receiving layer provided on the surface of a transparent film is preferred.

However, in the case of coated synthetic paper with an image-receiving layer provided on the surface of a transparent film, clear images cannot be obtained due to the unevenness of the surface of the coated paper and the instability of the adhesion between the head and the receptor sheet. do not have. Another drawback is that even if you try to write the contents of the image on the transparent film on the back side with a pencil or the like, you cannot do so.

On the other hand, when synthetic paper made of a rolled thermoplastic resin film containing fine inorganic powder is used as a support for a #i image-receiving sheet for thermal transfer recording, its back surface exhibits pencil-like properties, water resistance, and dust-free properties. Although there are concerns about image decipherability, the adhesion between the head and the gage receiving sheet remains unstable. That is, the synthetic paper made of this stretched film has a structure in which the core is inorganic fine powder, fine voids are formed around the powder by stretching, and the powder protrudes from the surface.

In this synthetic paper, the specific surface area is 1 as an inorganic fine powder.
o, o o Even if oaA/ or more is used, coarse particles or aggregates of the contained inorganic fine powder may protrude from the surface, and in this case, the thermally transferred image may be chipped ( There is a problem of contaminating the animal equipment where white spots) occur.

The above-mentioned Japanese Patent Application Laid-Open No. 59-85972 discloses that in order to improve the reproducibility of dots, a smoothing coat layer with a Peck index of 100 to 3000 seconds is provided on the surface of synthetic paper as a support. An image receiving sheet for thermal transfer recording is proposed in which an image receiving layer is provided on the surface of a chemically treated coating layer, and the projection height of the image receiving g 13 is 3 microns or less, and the waviness is within 10 microns per inch.

It is known that the smoothness of the image-receiving sheet can be increased in this way in order to solve the problem of image chipping and omission. However, with a highly smooth image-receiving sheet, the transfer of ink to the image-receiving sheet becomes uncertain and the image becomes unclear.
2500 seconds) and the surface is rough and the print surf roughness is 0.
．． It has been pointed out that it is preferable to use an image-receiving sheet for thermal transfer recording with a thickness of 6 to 5 microns (Japanese Patent Laid-Open No.
No. 0-110488).

However, according to our study, although the support requires f4 roughness and smoothness from a macroscopic perspective, it is rather necessary to have a protrusion that is isolated and protrudes from the surface of the support ( The width and height of the protrusions), the ITIA number, and the compressibility of the synthetic paper used as the support have a great effect on preventing color loss during thermal transfer printing and on the clarity of transfer printing.

[Specific means for solving the four points in between] In the present invention, the width, height, and solid number of the protrusions on the surface layer are made smaller and lower by adjusting the content of the inorganic fine powder and the thickness of the surface layer. , to impart smoothness to the surface of the synthetic paper, and to improve the surface smoothness of the synthetic paper ('!4 1986-7995).
No. 1, JP-A-61-23748, Tokuto-Sho 60-2
29353, specification of 60-290180), the compression ratio is 20 to 40%, which is higher than the 8 to 18% compression rate per cylinder.
The synthetic paper was given a soft feel to improve the adhesion between the head and the image receiving sheet, so that the transferred print would be clearer.

That is, the first aspect of the present invention is that (A) the inorganic fine powder is
a surface layer of a thermoplastic resin film containing 11%; and G)
A synthetic paper with two or more layers containing at least a stretched resin film core layer containing many microvoids containing inorganic fine powder with a specific surface area of 10,000 ctd/f or more than the content of inorganic Ia@ powder in the surface layer. The synthetic paper has (a) a compression ratio of 20 to 40%, and (a)
, to provide a synthetic paper with a multilayer structure, wherein the surface layer has a maximum length of 50 microns or more of protrusions protruding from its flat surface at a rate of 10 or less per 0.1 m'. It is something.

The second aspect of the present invention is a synthetic paper having a back layer soaked with more oil-based ink than the first synthetic paper. Thermoplastic -!!!The surface layer of the 4-fingered film and (B) Himo surface contain a large number of microvoids containing inorganic fine powder of 10,000 filtration/2 or more, which is more than the content of the inorganic fine powder in the surface layer. - A synthetic paper with three or more layers comprising at least a core layer of a stretched resin film and a back layer made of a stretched resin film containing 25 to 65% by weight of inorganic fine powder, the synthetic paper comprising: (b), the compression ratio is 20 to 40%, and ←),
The surface layer (A) has protrusions that protrude from the flat surface with a maximum length of 50 microns or more at a rate of 1 per 0.1 m2.
To provide a synthetic paper having a repeating structure characterized in that the number of repeating structures is 0 or less.

(Resin material) Thermoplastic resins constituting each layer of synthetic paper include polyolefin resins such as polyethylene, polypropylene,
Ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, poly(A-methylpentene-1), polystyrene, polyamide, polyethylene terephthalate, partial hydrolyzate of ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer Polymers and their salts, vinylidene chloride copolymers such as vinyl chloride-vinylidene chloride copolymers,
Others, and mixtures thereof can be exemplified. Among these, polyolefin resins such as polyethylene and polypropylene are preferred in terms of solvent resistance.

(Inorganic fine powder) Examples of the inorganic fine powder with a specific surface area of 10,000 cA/9 or more include calcium carbonate, calcined clay, diatomaceous earth,
Examples include talc, titanium oxide, barium sulfate, aluminum sulfate, and silica. In particular, the inorganic fine powder blended into the surface layer should be carefully
It is preferable that the residual amount of 25 mesh is 10 ppm or less.

(Surface layer) The surface layer (A) is a thermoplastic resin film containing 0 to 25% by weight, preferably 3 to 8% by weight, of inorganic fine powder, and this film may be oriented or not. It doesn't have to be.

In this surface smoothness, in order to prevent discoloration, the maximum length of protrusions protruding from the flat surface of this surface layer is preferably 50 microns or more per 0.1 m' or less.Surface smoothness ( The blending amount and type of the inorganic fine powder are selected so that the smoothness is high and the Beck index is 2,500 to 15,000 seconds.

(Core layer) The core layer gives the synthetic paper a soft feel and has a specific surface area of 10,000 ad/f or more, preferably 15,000 ad/f or more.
A resin film containing ~500,000 cd/f of inorganic fine powder in an amount larger than the inorganic fine powder content of the surface layer (8 to 55% by weight, preferably 10 to 25% by weight) is prepared at a temperature lower than the melting point of the resin. This is a stretched film in which a large number of fine (r to ) ρ micron) microvoids are formed inside the film by stretching the film with inorganic fine powder as cores.

This core layer covers the other 1 m2 of synthetic paper (surface layer, back layer,
The compression ratio of the synthetic paper itself, including the base material layer (described later), is 20~20.
The wall thickness, stretching ratio, bulk density, etc. are determined so that the thickness is 40% and Fumiko's weight is 1 θ to ρ %.

The large number of microvoids contained in the core layer (6) imparts compressibility to the synthetic paper. For example, when a load of 32/-, which is equivalent to the head pressure, is applied to the surface of synthetic paper,
The thickness of the synthetic paper can be compressed by about 20 to 30%.

This compression improves the adhesion between the receiving sheet surface layer and the thermal transfer dye-containing film (thermal transfer ribbon) when the synthetic paper is used as a support for a receiving sheet for thermal transfer images, and prevents protrusions on the synthetic paper surface layer. Even if there is a transfer image, the resulting transferred image has excellent clarity as a result of being pushed inside.

(A-side layer) When the synthetic paper is expected to have pencil writing properties, a back layer 0 made of a stretched resin film containing 25 to 65 1% by weight of inorganic fine powder is provided on the side opposite to the front surface. This back layer also has the effect of improving the roll slipperiness of the synthetic paper during thermal transfer.

(Synthetic paper) The synthetic paper of the present invention can be produced by, for example, extruding the resin composition for the core by volume to obtain a film, longitudinally stretching this by 4 to 10 times using the difference in peripheral speed of the rolls, and then A surface layer (A) obtained by melt-laminating a resin composition film for forming a surface layer on one or both sides of a stretched film and then laterally stretching it 5 to 12 times in a tenter is a -axis oriented film and a core. The layer (B) may be a biaxially oriented film, or the layer (B) may be a biaxially oriented film.
In the axially stretched film, the core layer 63) may be a biaxially stretched film.

Furthermore, (1) the resin composition for forming the surface layer, the resin composition for forming the core, and if necessary the resin composition for forming the back layer are melt-kneaded into one co-extrusion die using separate extruders. After being supplied and laminated in a die, the laminated film may be extruded and stretched in 24 directions to form a 24-stretched film. In addition, on at least one surface of the longitudinally stretched resin film (for base layer) containing 3 to 50% by weight of inorganic fine powder, a copolymer comprising a resin composition for forming a surface layer and a resin composition for forming a core layer is added. The extruded film may be melt-laminated, and then this laminate is stretched in the transverse direction to form a synthetic paper in which the surface RA and the core layer are uniaxially stretched films, and the base layer is a biaxially stretched film. Furthermore, in the synthetic paper manufacturing method of ■ this ■, the surface layer/core layer/base layer obtained by changing the resin composition for weakly forming the surface layer laminated on the other surface to the resin composition for forming the back layer. /Middle core layer/S side layer 5
It may be a synthetic paper with a layered structure or a synthetic paper with a four-layer structure of (1) front in If1/core layer/base layer/back layer (see FIG. 2).

This multilayered synthetic paper has a core layer containing a large number of microvoids produced by multiple stretching processes. When synthetic paper is used as a support for a thermal transfer image-receiving sheet, these microvoids provide good adhesion to the transfer paper, and in particular, the protrusions (convexities) on the surface layer are pushed into the support, making transfer easier. The white spots that sometimes occur are reduced.

The amount of internal microvoids in this microvoid-containing synthetic paper was measured using a sample piece of 10m x 10o
+s synthetic paper 200. 160# under 65% humidity condition
When a load (area 5-) is applied in the linear direction, the compression ratio is calculated as (based on JIS K-6734)
is 20 to 40%.

If the compression rate is less than 20%, it will be difficult to prevent color loss caused by protrusions on the surface of the synthetic paper during thermal transfer printing. On the other hand, if the compression rate exceeds 40%, the pressure of the thermal head during transfer will not be applied to the surface of the synthetic paper, and the pigment or dye in the transfer ribbon will not be transferred to the image receiving sheet.

The wall thickness of synthetic paper is 40 to SOO microns, preferably 40
~350 microns. The core layer (B) accounts for 40% or more of the total thickness of the synthetic paper.

The thickness of the surface layer is 10 to 40% of the total thickness of the synthetic paper.
It is preferable that If the surface layer is too thick, the compressibility of the core layer cannot be utilized, and if it is too thin, the surface smoothness is too low, causing color loss.

Preferred resin compositions for propylene resin synthetic paper are as follows.

■Surface layer composition: (a), polypropylene 35-97% by weight (b)
, polystyrene, high density polyethylene, medium density polyethylene, low density polyethylene, resin selected from ethylene/vinyl acetate copolymer 0-30% by weight (C), inorganic fine powder 0-1011%)
Core layer composition 2 (a), polypropylene 50-9ogli%Φ)
, resin selected from high-density polyethylene, medium-density polyethylene, low-density polyethylene, and ethylene/vinyl acetate copolymer O~30% by weight 5 (C), inorganic fine powder 10~25% by weight 0 Back layer composition: (a) , polypropylene 40-75% (b)
, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene/vinyl acetate copolymer 0 to 15% by weight (C), inorganic fine powder 25 to 50 weight 50 base layer (a), polypropylene 60 to 85 weight 1 %(b)
, polystyrene, high-strength polyethylene, medium-density polyethylene, low-density polyethylene, 3-10 ethylene/vinyl acetate copolymer (C), inorganic fine powder 10-30% by weight.

This synthetic paper uses polypropylene as a film matrix resin, and component Cb) such as polyethylene contributes to improving stretchability and impact resistance, but excessive addition leads to a decrease in microvoid formation.

As the inorganic fine powder of component (c) increases, the number of pores inside the film increases, improving compressibility and opacity, but decreasing the strength of the synthetic paper. Therefore, the content of the inorganic fine powder in the surface layer is made smaller than the content of the inorganic fine powder in the core layer for the purpose of increasing the surface strength of the synthetic paper and smoothing the synthetic paper to prevent discoloration.

The base material layer 0 is also the core layer 0. Therefore, in the present invention, the core layer and the base layer are conveniently expressed as a base layer due to the difference in the number of stretching axes, but as a technical interpretation of rights, the base layer is also treated as a core layer. Should.

(Protrusions) The protrusions 14 that protrude from Table 1■13 of the surface layer (A) of the synthetic paper are those whose major axis 2 is 50 microns or more as shown in Figure 3, which is 0.1 = this article 10 It is important that the number of defects be less than 100% in order to prevent defects in the thermally transferred image from becoming infrequent in practical use.

Even if the average particle size of the inorganic fine powder is less than 10 microns, there are small amounts of particles with particle sizes of 15 microns or 20' microns9, and the long diameter of multiple particles aggregates. There are some that are as huge as 50 microns. If these giant particles exist on the surface of the support 12 of the image-receiving sheet 1, the J-plane image-receiving layer 11 provided thereon will not be able to form a uniform film, and in severe cases will form pinholes, which will cause white spots. becomes.

The height h of the protrusions protruding from the flat surface of the resin surface layer 3 on the surface of the support 12 is smaller than the major axis 2 of the inorganic fine particles. This protrusion with a height h of 20 microns or more is 0.
From the viewpoint of preventing white spots, it is preferable that the number of particles is 5 or less per 1 m''.

(Image-receiving sheet) The image-receiving sheet 1 for thermal transfer recording is obtained by using the synthetic paper 12 of the present invention as a support and providing the image-receiving layer 11 on this support.

The image-receiving layer is made of a resin, rubber, wax, or a mixture of these and an organic or inorganic filler that is dyeable with sublimable or vaporizable dyes.

Resin, rubber, wax, etc. may be used after being dispersed in water or dissolved in an organic solvent.

Examples of resins, rubbers and waxes include: i, such as amino alkyd resin, polyamide, polyurethane, polyvinyl chloride, polyvinyl acetate, polyester, acrylic resin, acetal resin, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetal ,polystyrene,
Adhesives made from rubber such as polycarbonate, epoxy resin, styrene-butadiene rubber (SBR), and nitrile rubber (NBR), water-insoluble polymers such as ethyl cellulose and petroleum resin, or vegetable-based adhesives such as carnauba wax and wood wax. It is made by using a combination of solid waxes such as animal waxes such as wax, beeswax and serratus wax, petroleum waxes such as microcrystalline wax and paraffin wax, and synthetic waxes such as oxidized waxes and ester waxes.

As the inorganic filler, synthetic silica such as white carbon with an average particle size of 0.5 microns or less, inorganic pigments such as clay, Merck, aluminum sulfate, titanium dioxide, zinc oxide, etc. can be used, preferably an id average particle size of 0.1 μm. The following synthetic silicas such as white carbon and inorganic pigments such as light or heavy calcium carbonate can be used.

Various fine polymer particles can be used as the organic filler, but the particle diameter is preferably 10 μm or less.

Examples of polymers for which organic polymers are purchased include methylcellulose, ethylcellulose, polystyrene, polyurethane, J-carbon/formalin resin, melamine resin, phenol resin, iso(or diiso)butylene/maleic anhydride copolymer, and styrene. /maleic anhydride copolymer,
Polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyester, polyacrylic ester, polymethacrylic ester, styrene/butadiene/
Examples include acrylic copolymers.

These fillers are usually used in summer at a proportion of 30% by weight or less. In particular, inorganic fillers can be treated with nonionic, cationic, or amphoteric activators such as funnel oil, sodium dodecyl sulfate, organic amines, and sodium metal soap ligninsulfonate to prevent wetting of the transfer paper 2 with the ink. It has been improved and can be used suitably.

The image-receiving layer 11 is formed by coating and drying the surface layer (g) side of the support 12. For coating, play)”=r
-p, air coater (use a regular coating machine such as a coater, roll coater, bar coater, size press, gate roll device, etc.).

The thickness of the image-receiving layer 11 is between 0.5 and 20 microns, preferably between 3 and 15 microns. After coating and drying, the image-receiving sheet may be compressed using supercardan to give it smoothness, and the smoothness of the sheet may be adjusted to A.

Production Example of Synthetic Paper Example 1 (1) Calcium carbonate 16 with a specific surface area of 15,000 ad/f is added to a mixture of 79% by weight of polypropylene with a melt index (MI) of 0.8 and 5% by weight of high-density polyethylene.
% by weight a3), kneaded in an extruder set at 270°C, extruded into a sheet, cooled with a cooling device,
A non-stretched sheet was obtained. This sheet was heated to 140°C and then stretched 5 times in the machine direction.

+21MI4. (C) 95% by weight of polypropylene,
Average particle size 1.5μ, specific surface area 15,000 f/? ri
Composition (A) mixed with 5% by weight of calcium carbonate is melt-kneaded in an extruder, and the extruded sheet is laminated on one side of the 5-fold stretched sheet of (1) to form the 5-fold stretched sheet of (1). On the other side of Strongly kneaded, extruded and laminated, then cooled at 60°C, heated to 162°C, stretched 7.5 times in the transverse direction with a tenter, annealed at 165°C, cooled to 60°C, and removed the edges. Slit and 3 layers (A/B/C wall thickness 10/7
A synthetic paper with a structure of 0/30 micron) was obtained.

The Beck index of the surface (A) of this synthetic paper was 5,800 seconds, the opacity was 95.6%, and the compression rate was 25%.

In addition, the number of protrusions that protrude from the resin surface layer 3 of the surface layer (G) and have a longer diameter β of 50 microns or more is 0.1 m.
4 pieces per unit, and 0.0 pieces for items over 20 microns in height.
There was one piece per 1m2.

Example 2 (1) A mixture of 79% by weight of polypropylene with a melt index (MI) of 0.8 and 5% by weight of high-density polyethylene has a specific surface area of 15. Q 00c! 16% by weight of calcium carbonate of I/f was blended (B), kneaded in an extruder set at 270°C, extruded into a sheet, and cooled in a cooling device to obtain a non-stretched sheet. This sheet was heated to 140℃.
After heating, the film was stretched 5 times in the longitudinal direction.

(A1MI4.0ri710min polypropylene 97.5
Composition (A), in which 2.5% by weight of barium sulfate with a specific surface area of 25.000 cfI/liter was mixed with % of heavy duty, was melt-kneaded in an extruder, and the extruded sheet was placed on one side of the 5-fold stretched sheet of (1). Laminated and MI on the opposite side of the 5 times stretched sheet of (1)
4. The specific surface area of the polypropylene 55 (C) by weight is i
Composition C), which is a mixture of 45% by volume of calcium carbonate of 7t of ocra, was melt-kneaded in another extruder, extrusion laminated, cooled to 60°C, heated to 162°C, and transversely mixed with a tenter. 7.5 times stretching 1. ．． The surface of this synthetic paper was annealed at 165°C, cooled to 60'c, and the edges were slit to obtain a synthetic paper with a three-layer (A/B/C; wall thickness 10/70/30cm) structure. The Beck index of (A) is 5.500 seconds and the opacity is 96.5%.
The compression ratio was 23%.

In addition, the number of protrusions with a long diameter of 50 microns or more that protrudes from the resin surface layer 3 of the surface layer (end) is 0.1
7 pieces per m', and 0 for those with a height of 20 microns or more.
．． There were 2 pieces per 1 m''.

Example 3 The composition of surface l(A) is 981% polypropylene and a specific surface area of 30.000 crl/? of TiO2
Synthetic paper having the physical properties shown in Table 1 was obtained in the same manner as in Example 1 using a mixture with 2-70% by weight.

Example 4 The pond for changing the die slit width was made in the same way as in the implementation row 1, and the wall thickness was A/B/C: 5/70/1 s micron 31
A synthetic paper with a layered structure was obtained.

Fruit/cloth fI5 (1) Calcium carbonate 2 with a specific surface area of 15,000 IJl/P in a mixture of 9% by weight of polypropylene 2 with a melt index (MI) of 0.8 and 5% with high density polyethylene.
5% by weight (0) was mixed in an extruder set at 270°C, extruded into a sheet, cooled with a cooling device,
A non-stretched sheet was obtained. This sheet was heated to 140°C and then stretched 5 times in the machine direction.

+21 MI is 4. (C) polypropylene (3) and I
V114. Composition (B), which is a mixture of 255% by weight of polypropylene (C) and 40fiffi% of calcium carbonate with a specific surface area of 1 s and o o crli/y, is melt-kneaded in a separate extruder, laminated in a die, and formed into a sheet. Co-extruded and laminated both sides of the 5 times stretched sheet of (1) so that the front side is on the outside and [F] on the back side is on the outside).
Then, after cooling to 60°C, heating to 162°C, stretching 7.5 times in the transverse direction with a tenter, annealing at 165°C, cooling to 60°C, and slitting the edges.
5-layer structure (A/B/D, /A/B: wall thickness 5/15/6
A synthetic paper of 0/1515 micron) was obtained.

Comparative Example 1 The composition of the surface layer (A) has a specific surface area of s, oooc1
1/f calcium carbonate 5% by weight and M I 4. (C)
Example 1 except that a mixture of 95% by weight of polypropylene was used.
A synthetic paper having the physical properties shown in Table 1 was obtained in the same manner as above.

Comparative Example 2 A synthetic paper having the physical properties shown in Table 1 was obtained in the same manner as in Example 1 except that the slit width of the die was changed.

Comparative Example 3 (1) 5% by weight of calcium carbonate with a specific surface area of 15,000 cl/t was blended into a mixture of 90% by weight of polypropylene with a melt index (MI) of 0.8 and 5% by weight of high-density polyethylene (6) After mixing in an extruder set at 270° C., the mixture was extruded into a sheet and cooled with a cooling device to obtain a non-stretched sheet. This sheet, 14
After heating to 0°C, it was stretched 5 times in the machine direction.

(A1M I 4. (C) 95% by weight of polypropylene
A mixture of 5 wt.
f1 layer, and MI4.
(C) Polypropylene 55% by weight has a specific surface area of 15.
Composition 0 mixed with 45 MfJ% of calcium carbonate at 000 atl/f was melt-kneaded in another extruder, extrusion laminated, cooled to 60°C, and heated to 162°C to 17alo
It was stretched 7.5 times in the transverse direction using a tenter, annealed at 165°C, cooled to 60°C, and the edges were slit to form 3 layers (B/A/C; wall thickness 10/70/30 microns). ) structure synthetic paper was obtained.

In this synthesis, the Peck index of the surface ■ is 7. '500 seconds, opacity was 90.5% and compression was 15%.

In addition, the number of protrusions with a long diameter 2 of 50 microns μ that protrudes from the resinous surface layer 3 of the surface layer A is 8 per 0.1 m, and those with a height of 20 microns or more are 0.1 m.
It was 2 or 1.

Comparative Example 4 (1) Melt index (~II) 0.8. ) 79% by weight of polypropylene, 5% by weight of high-density polyethylene
Add 16% by weight of calcium carbonate with a specific surface area of 15,000 aA/l to the mixture of A non-stretched sheet was obtained.This sheet was
After heating to 0°C, it was stretched 5 times in the machine direction.

(A composition in which 55% by weight of polypropylene of A1MI4.o was mixed with 45% by weight of calcium carbonate of specific surface area ls, o o oal/y (O was melt-kneaded in an extruder, and the extruded sheet was mixed with (1) Laminated on both sides of a 5x stretched sheet, then cooled at 60'C'1, heated to 162°C, stretched 7.5x in the transverse direction with a tenter, annealed at 165°C, cooled to 60°C. , slit the ears and 3:
A synthetic paper with a circular (C/B/C: wall thickness of 10/70/30 microns) structure was obtained.

The surface of this synthetic paper (the Beck index of Q is 500 seconds, 9,
The opacity was 96.0% and the compression rate was 18%.

In addition, the number of protrusions with a long diameter 2 of 50 microns or more that protrudes from the resin surface layer 3 of the surface layer is 15 per 0.1 m2, and those with a height of 20 microns or more are 0.1 m2.
There were 6 pieces per 2 pieces.

Comparative Example 5 (1) Calcium carbonate 3 with a specific surface area of 15,000 cd/f was added to a mixture of 60% by weight of polypropylene with a melt index (MI) of 0.8 and 5% by weight of high-density polyethylene.
5% by weight was blended (6), mixed in an extruder set at 270°C, extruded into a sheet, and cooled with a cooling device to obtain a non-stretched sheet. This sheet was heated to 140° C. and then stretched for 5 times in the longitudinal direction.

(A) MIa,o polypropylene 95% by weight has a specific surface area of 15,000d/? A composition containing 5% by weight of calcium carbonate was melt-kneaded in an extruder, and the extruded sheet was laminated on both sides of the 5-fold stretched sheet of (1).
After cooling to 0°C, it was heated to 162°C, stretched 7.5 times in the transverse direction with a tenter, and annealed at 165°C.
Cool to 60'c, slit the ears and make 31cm (A/
B/A: Synthetic paper having a wall thickness of 10/70, /30 microns) was obtained.

The Beck index of this synthetic paper was 12.000 seconds, the opacity as a support was 97.5%, and the degree of compression was 4.2%.

However, the number of protrusions with a long diameter 2 of SO microns or more that protrudes from the resin surface layer 3 on the surface is 8 per 0.1 m', and only 0.1 m with a height of 20 microns or more.
There were 5 pieces per 2 pieces.

Note that the number of protrusions was measured by the following method.

+1) Shine an oblique light beam onto the surface of a synthetic paper sample cut to 20α×25α, visually search for protruding parts, and mark them.

(A) Observe the marked protrusions using a stereomicroscope set to 25x magnification, and count the number of protrusions with a major axis of 50 μm or more using a PEAK scale loupe.

(3) Do this for two samples, and let the total number be the number (diameter) of protrusions (A) per 0.1yn''.

(A) All of these protrusions were measured using a three-dimensional roughness analyzer Model 5PA-11 (product name) manufactured by Koita Research Institute, and the number of protrusions per 0.1 m' was measured for those with a height of 20 or more. (high).

Furthermore, the flat surface 18 of the synthetic paper refers to the surface 0 of the synthetic paper 2 cm away from the apex of the protrusion 14 as shown in FIGS. 3 and 4 in the direction of the major axis (1) of the protrusion. Upper point 16-
Draw a four-strip line segment 16.16' perpendicular to the major axis (A) of the protrusion, centering on a and 16-b, and draw this line segment 16.16'.
Continuous thickness gauge ELECTRONICMI made by Anritsu Electric ■
Measure with CROMETERK-306A (trade name) to find the highest point 17.17' of 16.16' on this line, and on the other hand, measure the surface of the synthetic paper in the direction perpendicular to the major axis (1) from the apex α9 of the protrusion. Draw 41 line segments 16", 16"' parallel to the major axis centering on points 16-c, 16-d 21 apart on 0, and use the thickness gauge above to draw 41 line segments 16", 16"' on these line segments 16", 16"". Measure and find the highest point 17", 17 on this line segment 16", 16"
Find N', select three points in order higher than 17.17', 17", 17"', and define the plane containing these three points as the flat surface 18.
(In Figure 5, the plane connecting 17, 17' and 17")
.

However, each line segment is 16.16', 16", 16 with a continuous thickness gauge.
Vertex measured above (17, 17', 17", 17//
) and the lowest point measured on the same line is 10 μm or more, new line segments 16-a and 16-b.

New center points 16-a and 16-d are added near 16-c and 16-d.
16-bXl 6-c or 16-d is provided and a flat surface 18 is obtained by the same procedure.

Table 1 shows the physical properties of the synthetic papers obtained in Examples 1 to 5 and Comparative Examples 1 to 5.

The evaluation as an image-receiving sheet for thermal transfer is based on the following method.

A coating agent having the following composition is applied to the surface layer (A) side of the synthetic paper to a solid content of approximately 105'/m'', and dried to form an image-receiving layer (thickness approximately 10 An image-receiving sheet provided with microns) was obtained.

(a) Polyester resin emulsion 40g (resin concentration 50%) ('b) Calcium carbonate 20 parts (c) Water 40 parts.

This image-receiving sheet for thermal transfer was evaluated by the following method. The results are shown in Table 1.

Image judgment method: (1) Prepared image receiving sheet and sublimable dye (trade name,
Kayaset Blue 136. Transfer papers coated with Nippon Kayakuryu (Nippon Kayakuryu) and dried were stacked and heated at 120° C. for 5 seconds to obtain an image. (A) The density and whiteness of the obtained image were evaluated on the following five scales.

Evaluation criteria 5: Very good 4 Good 3 No practical problems 2 Practical problems 1 Poor blocking resistance test 2 30c! ! Put the front and back sides of the 1×30m sample together and heat to 4.
It was left for 24 hours under a load of 5002 in a four-wall environment at 0° C. and 60% humidity.

Judgment was made based on the following criteria according to JIS K-6833.

× Blocking to the extent that damage is observed on the surface.

○ The sample is easily peeled off.

(Margin below)

[Brief explanation of drawings]

Fig. 1 is a plan view of a transfer thermal recording device, Fig. 2 is a sectional view of synthetic paper, Fig. 3 is a partial sectional view of synthetic paper, and Fig. 4 shows a method for determining the flat surface of synthetic paper. FIG. In the figure, 1 is an image-receiving sheet for thermal transfer recording, 11 is an image-receiving layer, 12 is a synthetic paper, 2 is a transfer body, 14 is a protrusion, A is a surface layer, B is a core layer, and C is a back layer. . Patent applicant: Oji Yuka Synthetic Paper Co., Ltd. Agent: Masahisa Hase Patent attorney: Takashi Yamamoto, patent attorney Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] 1) (A) a surface layer of a thermoplastic resin film containing 0 to 25% by weight of inorganic fine powder, and (B) a specific surface area of 1.
A synthetic paper with two or more layers including at least a stretched resin film core layer containing a large number of microvoids containing inorganic fine powder of 0,000 cm^2/g or more than the content of inorganic fine powder in the surface layer, The synthetic paper has (a) a compression ratio of 20 to 40%, and (b)
, wherein the surface layer (A) has a multilayer structure in which the number of protrusions protruding from the flat surface with a longest length of 50 microns or more is 10 or less per 0.1 m^2. paper. 2) (A) a surface layer of a thermoplastic resin film containing 0 to 25% by weight of inorganic fine powder; and (B) a surface layer with a specific surface area of 1
A stretched resin film core layer containing a large number of microvoids containing 0,000 cm^2/g or more of inorganic fine powder than the content of inorganic fine powder in the surface layer, and (C) 25 to 65% by weight of inorganic fine powder. A synthetic paper with three or more layers including at least a back layer made of a stretched resin film, which (a) has a compression ratio of 20 to 40%, and (b)
, wherein the surface layer (A) has a multilayer structure in which the number of protrusions protruding from the flat surface with a longest length of 50 microns or more is 10 or less per 0.1 m^2. paper. 3) Claims 1 or 2, characterized in that the core layer (B) and the surface layer (A) are oriented films obtained by stretching in one or two directions. Synthetic paper as described. 4), the surface layer (A) is a stretched film oriented in a uniaxial direction, and the core layer (B) is a stretched film oriented in a biaxial direction, or Synthetic paper according to item 2. 5), the thickness of the surface layer (A) is 1 to 15 microns,
4. The synthetic paper according to claim 3, wherein the thickness of the core layer (B) is 40% or more of the total thickness. 6), the thickness of the surface layer (A) is 1 to 15 microns,
5. The synthetic paper according to claim 4, wherein the thickness of the core layer (B) is 40% or more of the total thickness. 7), the thickness of the surface layer (A) is 1 to 15 microns,
3. The synthetic paper according to claim 2, wherein the back layer (C) has a wall thickness of 1 to 35 microns. 8) The content of inorganic fine powder in the surface layer (A) is 0 to 10% by weight, the content of inorganic fine powder in the core layer (B) is 10 to 25% by weight, and the content of inorganic fine powder in the back layer (C) is 25% by weight. The synthetic paper according to claim 2, characterized in that the content is 50% by weight.