JPS6323313B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a method for opacifying polyester yarns or fabrics containing polyester yarns with good coverage. It is known that the opacity of textile materials, ie, yarns, filaments, woven, knitted, non-woven fabrics, etc., can be enhanced by the addition of metal oxides such as titanium dioxide. By imparting opacity to thin or transparent fabrics, the hiding power of the fabric can be significantly improved and the extra weight and expense that would result in a heavy, tight web can be avoided. . When imparting opacity in this way, it is preferable to avoid adding too much opacity, which would impair the handling of clothing, and also prevent opacity from being damaged by repeated washing or dry cleaning. It is necessary to make sure that this does not happen. Titanium dioxide is known as a suitable material for imparting opacification to textiles. In the past, titanium dioxide was sometimes added to the molten polymer before the synthetic resin thread was extruded. In this case, the titanium dioxide will be distributed over the entire cross section of the thread. Furthermore, after fabrics, threads, non-woven fabrics, filaments, etc. have been made, titanium dioxide has been added to their surfaces by padding baths, spraying, dipping, etc. to impart opacity and the like. In particular, when imparting whiteness or opacity to textiles, etc., a binder was included together with titanium dioxide to improve durability against pigment removal by bending or washing the surface, dry cleaning, etc., in other words, against dusting. . However, in this case, the amount of binder required may make the fabric stiff. Furthermore, there is a possibility that titanium dioxide may migrate during drying in the padding operation, resulting in uneven distribution of titanium dioxide on the surface of the web. Binders and titanium dioxide (in the form of titanium salts or pigments) have traditionally been applied to textiles along with other ingredients in the form of dispersions, solutions or emulsions. The fabric is then further processed to improve adhesion of the added components. It is also known to use a titanium salt dispersion to fade cellulose acetate, rayon, and the like. In this case, the metal salt is subsequently treated with an acid to release metal ions deposited on the web under acidic conditions. Another method for applying titanium dioxide to textiles is the exhaust method.
technique) is used. In this case, titanium dioxide having a particle size of 0.1 micron or less is used. Titanium dioxide having such a particle size has no whitening effect and is used merely to prevent staining, and therefore does not improve opacity. Conventional methods of applying such titanium dioxide and other metal oxides to webs impart opacity to polyester yarn-containing fabrics without using the binder as a main means, which is the problem of the present invention, and are easy to wash and dry clean. No solution is provided to withstand repeated processes, etc., without risk of interfering with other textile processing operations, and to allow relatively large amounts of pigment to be added to the web without impairing the texture. . This invention was made in view of the above circumstances, and its purpose is to provide a polyester thread-containing fabric with good opacity. Another object of the present invention is to provide a polyester yarn-containing fabric that has improved opacity and is easy to handle, such as texture. Yet another object of the present invention is to provide a method for successfully adhering titanium dioxide to polyester yarn-containing fabrics without using a binder as the primary means. Another object of the present invention is to provide a method of adhering titanium dioxide to a polyester yarn-containing fabric by a discharge method to improve opacity without impairing handling properties. Furthermore, the purpose of this invention is to not only have superior opacity with respect to the amount of titanium dioxide per unit on an add-on basis compared to conventional products, but also to have a good cleaning effect and to prevent stains. It is an object of the present invention to provide a polyester yarn-containing fabric that also has good preventive properties. The polyester yarn-containing fabric according to the present invention is a polyester yarn-containing web to which 20% by weight or less of titanium dioxide particles with an average particle size of about 0.18μ or more are attached, and the particles can be easily absorbed even without adding a binder. Adhesion properties are determined by the American Association of Textile Chemists.
and Colorists (hereinafter abbreviated as AATCC), the particles attached to the fabric after 5 washes are
50% or more, it provides a fabric with good opacity and texture. Furthermore, according to the present invention, as is clear from the attached photograph, the attached particles are less likely to aggregate between the fiber threads. Additionally, the method of the present invention includes the steps of preparing an aqueous dispersion of a titanium dioxide pigment having a particle size of about 0.18 microns or greater, and contacting the dispersion with a fabric under agitation at a pH of about 7.5 or less, thereby dissolving the pigment. is discharged from the dispersion, which is then heat-treated. The polyester yarn-containing fabric according to the present invention may be in any form such as yarn, filament, woven fabric, knitted fabric, or non-woven fabric. The amount of polyester yarn contained in these fabrics is at least about
The content is 10% by weight, preferably 40% by weight or more. especially
More favorable results are obtained with 100% polyester fabric. The titanium dioxide used in this invention may be in the form of a pigment, in the analite or anatase crystal structure, and may also have an alumina or silica coating. The important point of this invention is to provide a polyester fabric with good opacity. Therefore, the particle size of the titanium dioxide should be at least 0.18 microns, which promotes the opacity of the fabric and improves its hiding power. Therefore, titanium dioxide suitable for the present invention needs to have a particle size large enough to provide a whitening effect on textiles. Approximately 7% by weight of titanium dioxide can be added to the fabric, so there is no risk of "dusting" even without the addition of a binder, and it also has good durability against washing and dry cleaning. It is. Further, when titanium dioxide is added in an amount of less than about 20% by weight (the same applies throughout the specification with respect to the weight of the fabric), only very slight dusting occurs even without the addition of a binder. If more pigment is desired, a small amount of binder, e.g., about 2% or less, can be used as a secondary binding means to reduce "dusting" and improve wash and dry cleaning resistance. You can also do so. In the method of this invention, titanium dioxide is dispersed in an aqueous medium with a basic PH such that a stable dispersion is obtained even under unstirred conditions. The polyester-containing fabric is contacted with this dispersion under stirring. During this contact, the pH of the dispersion gradually approaches about 7.5, at which point the pigment is drained from the dispersion into the fabric. Completion of the pigment discharge can be detected by the clearing of the bath. As a preferred method, the PH of the dispersion may be gradually reduced, such as by addition of acid or generation of acid.
Generating acid externally by adding an acid-generating compound to the dispersion allows for safe operation since the PH reduction of the bath can be easily controlled. The most preferred method is to add an acid-generating substance such as butyrolactone to the dispersion and generate the acid by heating.
Try to lower the pH gradually. To explain the best example, first, titanium dioxide having a particle size of about 0.2 μm is dispersed together with an alkali in an aqueous dispersion medium, and titanium dioxide is contained in an amount corresponding to about 5% by weight based on the weight of the fabric. PH of the bath
is approximately 9. The fabric is brought into contact with the dispersion under continuous stirring and the butyrolactone, colorant and coloring aid are added to the bath. The temperature of the bath is gradually increased at a rate of about 3° per minute to about 266°. As a result, the pH of the dispersion gradually decreases to about 4.7.
When acid is generated and the pH drops below about 7.5, titanium dioxide begins to discharge onto the fabric. When the pH approached 4.7 and the bath temperature reached 266㎜, the dispersion became clear, indicating that most of the titanium dioxide had been expelled. The fabric coated with titanium dioxide is then removed from the bath, rinsed, dried and heat treated. Titanium dioxide adheres substantially permanently to the fabric and requires no binder. Approximately 5% by weight of titanium dioxide is deposited on this fabric, which imparts opacity and does not affect the texture. This fabric can be further treated to impart stain and wrinkle resistance without impairing the durability of the titanium dioxide. Although a durable bond can be achieved without adding extra binder, a small amount of binder, for example, about 2% or less, may be added to further improve the bonding durability of the pigment. Generally, if a binder is added, it is only in a small amount, so there is no risk of it having an adverse effect on the feel of the textile and interfering with its use. The polyester thread-containing fabrics of this invention provide approximately twice the opacity compared to untreated fabrics. For example, the Hunter Color Difference
Measure the sample pill for reflection (L value) under white and black backgrounds with a
Expressed as the difference in ΔL for a completely transparent sample,
The value will be 100, ΔL for fully opaque samples
The value will be 0. Therefore, the ΔL value of the polyester yarn-containing fabric of the present invention is approximately half that of the untreated comparative sample. Generally, in the fabric of this invention, the area of titanium dioxide applied is 2 to 80%, preferably 10 to 40%, of the total surface of the fabric. The area covered can be measured by electronic micrographing of the fabric. If no pigment is applied at all, the application rate will be 0, and if the entire surface is completely applied, the application rate will be 100%. However, a coverage rate of 100% may not be necessary in practice. The products according to the invention have substantially improved hiding power compared to conventional products containing the same proportions of titanium dioxide. This improvement is surprising, but is probably due to the pigment particles being more uniformly dispersed than in the conventional case. This uniform dispersion is difficult to express clearly, but it will be clear from the attached photograph. Figures 1-3 show the product of the invention at 470x, 950x and 1900x magnification. This photographic sample was made using the same materials and method as in Example 1, and the pigment was
Titanox 1070 (manufactured by NL Industries) was used. If this is compared with the conventional product shown in FIG. 4, in which about 5% by weight of titanium dioxide is attached to the fibers by the padding method, its dispersibility can be clearly understood. Although the magnification of FIG. 4 is the same as that of FIG. 1, mutual aggregation of particles can be seen, particularly at the boundaries between fiber yarns. However, in the case of Figures 1-3, there is little agglomeration of particles, with an average agglomerate size of about 25 particles or less. The products shown in Figures 1 to 3 were obtained under ideal laboratory conditions (the same applies to Figure 4).
However, the agglomeration of pigment particles can also be reduced under factory production conditions, where the average agglomerate size is approximately 50 primary particles or less (5
(See Figure, 950x, Figure 6, 1900x). In some cases, the average agglomerate size may be slightly larger than the above, but this average agglomerate size also depends on how aggregation is defined. In any case, it will be clear from the attached photographs that the average aggregate size is significantly reduced by the present invention. This agglomeration reduction remains characteristic even after subsequent processing, as shown in Figures 7 (450x) and 8 (1900x). The products of this invention have improved hiding power, opacity, texture, etc. and, most importantly, good long-lasting bonding of the pigment with the fabric in the absence of a binder. The reason for this is not clear, but anyway the pigment particles are permanently attached to the textile surface. The durable bonding of this pigment particle is standard
Can be measured by AATCC wash.
This AATCC washing is a known method described in AATCC Technical Manual, Method 2. (Vol. 53, Page 253, ed. 1978). The durability of this bond depends on the amount of _TiO2 initially added, the method of application, the web composition,
Depending on the binder and other additives, the product of this invention has a standard AATCC rating of 5 times.
At least 50% after washing, in some cases
Shows a survival rate of 70% or more. Furthermore, in some cases, the survival rate can be over 80%. A further feature of the product of this invention is that it has improved "flat drying" compared to conventional products using binders. Furthermore, the product of the present invention has improved moisture wicking action compared to conventional products. The products of the present invention also have better soil release properties compared to conventional products using binders, promoting the effectiveness of known soil release agents. It should be noted that binders generally have a negative effect on soil release properties. Preferred specific examples of the present invention will be described below.
In the present invention, the polyester yarn-containing fabric may be yarn, filament, woven fabric, knitted fabric, non-woven fabric, etc., but is not particularly specified. When a strand of yarn, filament, etc. is made opaque, a web etc. made from it will naturally also be opaque. The extruded filament may have a circular cross section, but preferably has a non-circular cross section, such as a lobular or wavy filament. As used herein, "wavy" and "wavy"
This is in contrast to a smooth continuous filament yarn, and means one formed into wrinkled, looped, coiled, crimped, etc. shapes. This is formed to improve extensibility, loose firmness, absorbency, texture, etc. The most preferred wavy yarn in this invention is one to which false twist has been applied. This is well known and is produced, for example, using twisting machines from ARCT, Barmag, Berliner, etc. Particularly in the case of polyester yarns, such wavy yarns have characteristics similar to those of spun yarns, and have improved resistance to pilling and wrinkles, as well as improved shape retention, durability, and homogeneity. In the present invention, polyester fibers include all polyesters extruded into filaments. Polyesters are generally condensates of dicarboxylic acids or ester-forming derivatives with glycols such as dimethyl terephthalate, ethylene glycol, etc., and are glycol ester polymers of dicarboxylic acids. This polyester may contain other components that impart basic dyeability, antistatic properties, flame resistance, and the like. When using titanium dioxide with an average particle size of about 0.18 μm or more, the dispersion liquid can remain stable for a long period of time under alkaline conditions. When the PH of the dispersion changes to the acidic side, titanium dioxide is then discharged. When the dispersion gradually decreases its PH,
Uniform application of titanium dioxide to the fabric is achieved. In fact, it was surprising that a relatively large amount of titanium dioxide could be discharged onto the fabric by the method of the present invention, while still retaining good feel (or handleability) as a garment. Similarly, it was surprising that this pigment was easy to wash and had good holding power even after repeated dry cleaning and the like without using a binder as in the past. If the dispersion initially has an acidic PH, stirring may be necessary to obtain a stable dispersion. Uniform deposition of titanium dioxide will be worse than if the dispersion was initially at a basic PH. It is assumed that titanium dioxide begins to exit the dispersion at the isoelectric point where the charge changes from (-) to (+). In any event, when the pH of the dispersion reaches 7.5 or below, its drainage begins. of dispersion
When the pH gradually decreases, titanium dioxide deposits on the fabric without precipitation. A rapid decrease in PH prevents uniform application of pigment to the web and impairs the stability of the dispersion. Good dispersion of titanium dioxide in water is obtained by suitable methods. For example, the pigment may be predispersed in a dilute alkaline solution or the pigment may be added directly into an alkaline aqueous solution. Suitable alkaline substances include ammonium hydroxide, sodium hydroxide, and the like. After addition, if you stir it, the pigment will disperse and become milky, which will keep it stable. According to the invention, the amount of titanium dioxide in the dispersion is between 1.0 and 20% by weight, preferably between about 3 and 7% by weight, relative to the weight of the fabric to be treated. Up to 7% by weight of titanium dioxide can be deposited on textiles without causing any "dusting" and exhibits good durability against washing and dry cleaning. It is also possible to add 20% by weight of pigment, although this may cause slight "powdery". When carrying out the method of this invention, it is preferable to maintain continuous agitation between the dispersion and the fabric. This is done by agitating the dispersion or the fabric, or both. The method of this invention is not incompatible with the dyeing process, and is compatible with industrial dyeing equipment,
For example, it can be carried out using a jet rope dyeing device (one that processes the fabric into a rope shape and stirs it with a jet stream of water or the like). The web and dispersion are brought into contact, and the pH is lowered to promote exhaustion. As mentioned above, the way to lower this PH is to do it gradually. Gradually add an acid such as acetic acid to the dispersion to lower the pH. When the pH is about 4, it is preferred to heat the dispersion and complete the draining. When the pH is below 4, complete exhaustion of titanium dioxide occurs at room temperature. However, in a preferred embodiment, an acid generating compound is used to adjust the pH of the dispersion. This compound generates acid under predetermined conditions, such as heating, to lower the pH of the dispersion. Butyrolactone (SANDACID V, Sandoz Chemical Company) is an example of a preferred acid generating compound. Heating is controlled to limit acid generation. This allows the PH to be gradually lowered. Although this invention does not require any other means other than dispersing titanium dioxide in an aqueous medium and adjusting the pH of the dispersion, adding other components to the dispersion can also reduce the discharge of titanium dioxide. There is no particular problem as long as it does not have any adverse effects, does not impair the properties of the textile, and does not impair the sustainability of the treated product. For example, it is also possible to add a coloring agent, a coloring carrier, a leveling agent, a lubricant, a chelating agent, a binder, a small amount of a binder, and the like. Similarly, after improving the opacity or hiding power of a fabric using the method of this invention, the fabric can be treated to provide wrinkle resistance, stain resistance, flame resistance, etc. Further, depending on the case, it may be possible to carry out the method of the present invention simultaneously with the stain resistance imparting treatment. Regardless of whether the initial dispersion is alkaline or acidic, titanium dioxide emissions occur at a pH below 7.5. As mentioned above, it is preferable to initially make the dispersion alkaline and gradually make it more acidic. This results in uniform deposition of titanium dioxide. Whether the initial dispersion is alkaline or acidic, the pH drops to about 6 to 3, preferably about 5 to 4, at the time of discharge. Titanium dioxide applied to polyester fabrics in this way has a long-lasting effect even in the absence of other ingredients, and the subsequent application of anti-wrinkle agents, anti-stain agents, and small amounts of binders further improves its sustainability. will be improved. Also, heat-setting the polyester fibers after application of the titanium dioxide will further enhance its durability. Furthermore, this heat treatment makes it easy to wash.
The retention of titanium dioxide after dry cleaning will be further enhanced. Usually, heat treatment (heat setting) is carried out at a temperature of 300 to 400 °C and a residence time of 5 seconds to 2 minutes. As mentioned above, a binder is not necessarily required, but up to about 2% by weight of binder may be used to improve bond durability. Example 1 A piece of corrugated 100% polyester fabric was placed in a Mothis laboratory dyeing apparatus (type JF) and then
At 80°C, water was introduced in an amount 30 times the weight of the fabric, and stirring was started. Titanium dioxide pigment (TI-Pure 960, manufactured by Dupon) was dispersed in the ammonium hydroxide solution in a Waring stirrer for 5 minutes. Next, this titanium dioxide-ammonium hydroxide dispersion is added to the aqueous bath in the dyeing apparatus to an extent that the pigment accounts for 5% by weight of the fabric,
The pH of the bath was set to 9.0. Then, after stirring for an additional 5 minutes, butyrolactone (SANDACID V, Sandoz
Chemical Co., Ltd.) was added to the dispersion in an amount of 3% of the weight of the fabric. The temperature of this dispersion was increased by 3 times per minute.
It increased to 266〓 at a rate of 〓. After holding the temperature at 266° for 5 minutes, the bath was allowed to cool to 160°. The PH of the bath was now 4.7 and transparency appeared indicating pigment discharge. The fabric was then removed from the bath, rinsed once, dried, and then
Heat treatment was performed for 1 minute at a temperature of 〓. The treated fabric was found to have significantly improved opacity compared to a comparison fabric similarly treated in the absence of titanium dioxide. Gravimetric analysis revealed that 95% of the titanium dioxide was discharged from the dispersion onto the fabric. The impermeability of this fabric was maintained through repeated washing and dry cleaning, demonstrating its good durability. In other words, the remaining titanium dioxide after 5 AATCC washings is approximately
It was 70%. Example 2 A piece of corrugated 100% polyester fabric was placed in a cold water beaker. At this time, the weight ratio of water to fabric is
It was 30:1. After stirring this, ammonium hydroxide was added to the bath to adjust the pH of the bath to 10.0. Titanium dioxide pigment (particle size 0.22 microns) was then added to the bath in an amount to give a weight ratio of 7% to the fabric. After stirring for 5 minutes, acetic acid was gradually added over time to adjust the pH of the bath to 4.0. Then, the bath temperature was gradually raised to 212㎓. Significant emissions of titanium dioxide pigment were observed when the temperature was approximately 158°C.
After holding at 212〓 for 15 minutes, the bath becomes clear;
It was shown that almost all of the titanium dioxide was discharged. After removing the fabric from the bath, dry it to 360℃.
After curing for 30 seconds, measurements showed that 95% of the titanium dioxide had been discharged onto the fabric.
This fabric had improved opacity, and it was washable and showed persistence even after dry cleaning. Substantially no "flour" was generated and the product had a good texture.
70% of the titanium dioxide remained after 5 AATCC washes. Example 3 The same procedure as in Example 2 was carried out except that the bath temperature was kept at room temperature. Almost all of the titanium dioxide was discharged onto the fabric, and an improvement in opacity was observed. Note that it took a relatively long time to completely complete the discharge. 5 AATCCs
Approximately 60% of the titanium dioxide remained after washing. Example 4 A polyester fabric was treated in the same manner as in Example 1. This treated sample was evaluated in comparison to an untreated comparative example, and the initial opacity and 120° opacity after repeated 5 minute washes were measured. Opacity was determined using a Hunter colorimeter. A ΔL value of 0 indicates complete opacity, and a value of 100 indicates complete transparency. The results are shown in the table below.

[Table] Example 5 Fabric samples treated in Example 1,
The household washing operation was repeated five times, including some that were not heat set. During this time, the amount of titanium dioxide was checked from time to time to measure its persistence on the web. The results are shown in the table.

TABLE The amount of TiO ₂ indicates the amount of titanium dioxide remaining on the web and is a measure of the corrected intensity of X-ray fluorescence per second. From this result, it was confirmed that heat-set products had improved durability and a considerable amount of titanium dioxide remained even after washing. Example 6 The same procedure as in Example 1 was carried out except that the 100 polyester fabric was only dried but not heat set. The fabric is then padded with an emulsion containing methyl acrylate/acrylic acid copolymer (70:30) to reduce the weight of the fabric by 0.3%.
% of the copolymer was deposited. After drying this, it was heat set at 350° for 1 minute. As a result, it was possible to provide long-lasting hiding power and stain release properties. Furthermore, the residual rate of titanium dioxide after washing with AATCC five times was about 70%. Example 7 The same procedure as in Example 1 was carried out, except that a pink dispersed colorant was added to the bath so that 0.1% of the colorant based on the weight of the fabric was deposited. As a result, the same opacity as in Example 1 was imparted, and a pink colored product was obtained. I want to wash this
As a result of repeated dry cleaning treatments, special coloring and hiding properties were observed. Example 8 It is known that titanium salts can be applied as a dispersion to fabrics, such as cellulose acetate, rayon, etc., to erase them. In that case, the discharge method uses titanium dioxide with a particle size of 0.1μ or less. Thus, compared to those using conventional evacuation methods, those according to the present invention have a variety of better physical properties. The table below shows fabric samples of the present invention that do not contain titanium dioxide (comparative example). The sample of the present invention is a sample obtained by processing in the same manner as in Example 1, except that the pigment Titanox 1070 (anatase, manufactured by NL Industries) was used.

[Table] In addition, Column 3 shows a sample treated with the known evacuation method described in Example 1 of U.S. Patent No. 2309964, in which the same type of titanium dioxide as in Column 2 was ejected from an aluminum formate-containing bath. did. The sample in column 4 shows the characteristics of a sample subjected to padding according to the method of Example 2 of the above-mentioned US patent ('294 patent). The samples in column 5 are those in column 3 and were treated in the same manner as in Example 1 of the above-mentioned US patent, except that a bath containing aluminum sulfate was used instead of aluminum formate. In this table, P is "poor", FG is "good to excellent",
G means "excellent", VG means "excellent", and E means "best". Example 9 This example uses the same samples used in Example 8 and Tables, but was prepared using the method of Example 6 to prepare a methyl acrylate/acrylic acid copolymer (70:30),
Packing with a soil release emulsion containing ethoxylated polyester and a lubricant (ethoxylated oleic acid), whereby copolymer 0.3
%, ethkylated polyester 0.15%, lubricant 1.0%
(Both are based on the weight of the fabric). The properties of the resulting fabric are shown in the table.

Table: Example 10 Example 1 was repeated using a piece of spun polyester fabric in place of the corrugated polyester. The treated fabric had significantly improved opacity (ΔL value = 9.1). On the other hand, the comparative product containing no titanium dioxide had a ΔL value of 18.3. After repeated washing (5 washes) the ΔL value was 13.0, whereas in the comparative example the ΔL value was 18.2. Example 11 The same procedure as in Example 1 above was repeated using a piece of uncorrugated 100% polyester fabric instead of the corrugated 100% polyester. The opacity of the fabric treated in this way was significantly improved (ΔL value = 17.0). However, a comparative sample treated in the same manner without adding titanium dioxide had a ΔL value of 28.5. Example 12 The same procedure as in Example 1 was repeated using a nylon taffeta fabric instead of the corrugated polyester of Example 1. Fabrics treated in this way had improved initial opacity compared to a control sample similarly treated without titanium dioxide (ΔL value = 24.5), but only slightly after five standard AATCC washes. Only 8.7% of the titanium dioxide remained. Example 13 The same operation as in Example 1 was repeated using 100% acrylic fiber fabric instead of the polyester in Example 1. Fabrics treated in this way had improved initial opacity (ΔL value = 3.2) compared to a control sample similarly treated without titanium dioxide (ΔL value = 15.0), but compared to the 5 AATCC standard. After washing, only 25% of the original titanium dioxide remained. Example 14 The same procedure as in Example 1 was repeated using a 65/35 polyester/cotton blend fabric instead of the polyester in Example 1. Although the fabric treated in this way had improved initial opacity compared to the comparative example that was treated in the same manner without containing titanium dioxide (ΔL value of the comparative example = 16.0, ΔL value of the present example = 6.2),
After five AATCC standard washes, only 24% of the original titanium dioxide remained. The ΔL value after washing five times was 10.2, which was better than the initial ΔL value of the comparative example that did not contain titanium dioxide.

[Brief explanation of drawings]

Figures 1 to 3 are micrographs of fibers treated by the method of the present invention, Figure 4 is a microscope picture of fibers treated by the conventional method, and Figures 5 to 8 are micrographs of fibers treated by the method of the present invention. FIG. 3 is a micrograph of treated fibers.

Claims (1)

[Claims] 1 (a) Titanium dioxide with a particle size of 0.18μ or more, PH7.5
(b) Next, the fabric to be treated is brought into contact with the fabric to be treated under stirring, and the pH of the dispersion is gradually lowered from 7.5, thereby transferring titanium dioxide from the dispersion onto the fabric. 1. A method for opacifying a polyester yarn-containing fabric, comprising the steps of: (c) discharging the fabric into a polyester yarn; and (c) then heat-treating the fabric.