JP2007262600A - Photocatalyst carrying sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relate to a photocatalyst carrying sheet on which photocatalyst particles having extremely high oxidizing power are carried, and particularly to reduce deterioration of constituent fibers of the carrying sheet due to active chemical species generated from the photocatalyst particles, The present invention relates to a technique capable of avoiding the dropping of the photocatalyst particles and the decrease in mechanical strength of the sheet.
SOLUTION: In a photocatalyst carrying sheet comprising a fabric having photocatalyst particles carried on the surface layer of a constituent fiber comprising at least a surface of a thermoplastic resin, two types of hindered amines are used for the thermoplastic resin constituting the surface layer of the constituent fiber described above. A stabilizer, a hydroxylamine stabilizer, a hindered phenol stabilizer, and a phosphorus stabilizer are added.
[Selection figure] None

Description

  The present invention relates to a photocatalyst-carrying sheet that can receive light of a predetermined wavelength and purify by oxidation, such as a filter for purifying air and water, and particularly relates to a technique that can avoid strength reduction due to deterioration.

  It is widely known that photocatalysts such as titanium oxide decompose, for example, organic substances that are the cause of bad odor by virtue of their strong oxidation reaction. Therefore, it is used in the form of a sheet composed of fibers such as a knitted fabric, a woven fabric, or a non-woven fabric (hereinafter sometimes simply referred to as a fabric) because of its handleability in use.

  Various techniques for supporting particles made of a photocatalyst on a cloth have been proposed, and techniques for adhering to a cloth as a mixture of the particles and various binders have been used from early on. As an example of such a fixing technique, Japanese Patent Application Laid-Open No. 2003-213564 (hereinafter referred to as Patent Document 1) is a fiber structure in which titanium oxide having a photolytic catalytic function (photocatalytic titanium oxide) is fixed by a binder resin. Thus, a deodorant fiber structure is proposed in which this photocatalytic titanium oxide is coated with an amphoteric polymer having a light transmittance of 80% or more at a wavelength of 380 nm. The technique disclosed in Patent Document 1 aims to eliminate degradation of the fiber structure or the binder resin constituting the fiber structure by the oxidizing power of a strong photocatalyst. In order to achieve such an object, a copolymer of acrylic acid, acrylamide and dimethylaminomethylacrylamide is exemplified as a preferred form thereof. By providing the light transmittance requirement described above, a fiber structure is formed by photocatalytic titanium oxide. And a good deodorizing effect without deteriorating the binder resin.

  In addition, a technique is known in which secondary processing is performed on the photocatalyst particles themselves so as to reduce deterioration of organic materials such as a cloth as a base material. As an example, Japanese Patent Application Laid-Open No. 2001-286728 (hereinafter referred to as Patent Document 2) discloses that the surface of a photocatalyst is coated with a porous ceramic film that is inert to the photocatalytic action and has a large number of pores. Techniques for producing photocatalysts are disclosed. The technique of Patent Document 2 applies a metal alkoxide, which is a precursor of ceramics, to a photocatalyst such as titanium oxide, zinc oxide, iron oxide, cadmium sulfide, cadmium selenide, strontium titanate, aluminum, silicon, A porous ceramic film made of zirconium, magnesium, calcium, titanium or the like is provided for coating.

  In any of the above-mentioned patent document techniques, the photocatalyst particles are partially or entirely covered with a binder or ceramic material, and various kinds of particles are used to effectively function the particles exposed on the fiber surface constituting the fabric. The problem is left. On the other hand, for example, in Japanese Patent Application Laid-Open No. 2003-286661 (hereinafter referred to as Patent Document 3), the present applicant has at least the surface of a fiber made of a thermoplastic resin higher than the melting point of the resin constituting the fiber surface. A technique for fixing solid particles having a melting point or decomposition temperature is proposed. According to the technique of the said patent document 3, the structure which the solid particle heated more than melting | fusing point of a fiber is made to contact the fiber surface with various heating techniques is employ | adopted. For this reason, only the part where the solid particles are in contact with the surface of the fiber melts, and when the solid particles are fixed to these fabrics, the solid particles are less likely to be buried in the fiber, and the fiber itself is less likely to break or shrink. The function of the solid particles can be effectively exhibited.

JP 2003-213564 A ([Claims], [0003], [0009], [0028]) JP 2001-286728 A ([Claims], [0006], [0011], [0014]) JP 2003-286562 A ([Claims], [0002], [0003], [0027])

  As described above, when the photocatalyst particles are supported on the sheet material, the binder utilization technique represented by Patent Document 1 can be used to generate hydroxyl radicals or superoxide anion radicals generated from the photocatalyst itself even if the light transmittance of the binder is increased. As long as a function such as deodorization is expected by generating active oxygen, it is extremely difficult to eliminate the deterioration of the binder. In addition, when secondary processing is performed on the photocatalyst particles as typified by Patent Document 2, the coating formed on the surface of the catalyst particles by the processing includes photocatalyst particles and an environment in which this type of sheet is used. The contact area is also reduced, and an efficient photocatalyst carrying sheet has not yet been realized.

  On the other hand, as described above, the present applicant has proposed a technique that can achieve practical fixing strength substantially only with a fabric and photocatalyst particles, as described in Patent Document 3, for example. However, even with this technique, sufficient fixing strength can be achieved during sheet production, but active oxygen due to the photocatalyst particles gradually deteriorates in the vicinity of the interface between the fibers and the photocatalyst particles. There was a problem that it dropped off or the strength of the fabric was lowered after the dropping.

  In order to solve such problems, the inventors of the present application paid attention to various stabilizers for the purpose of preventing the deterioration of the fiber, and as a result of intensive studies, the present invention has been completed. Therefore, in view of the above-mentioned conventional problems, the present invention provides a photocatalyst-carrying sheet made of a fabric carrying photocatalyst particles that generate active oxygen by light, without substantially impairing the function of the particles. An object of the present invention is to provide a technique capable of exhibiting an excellent function for a long period of time and having little reduction in the strength of the sheet.

  In order to achieve this object, according to the configuration of the present invention, in the photocatalyst-carrying sheet made of a fabric in which photocatalyst particles are carried on at least the surface of the constituent fiber made of a thermoplastic resin, the surface layer of the constituent fiber described above is used. And hindered amine stabilizers of the following formula (1) (hereinafter referred to as stabilizer A) and hindered amine stabilizers of the following formula (2) (hereinafter referred to as stabilizer B). A hydroxylamine stabilizer of the following formula (3) (hereinafter referred to as stabilizer C), a hindered phenol stabilizer of the following formula (4) (hereinafter referred to as stabilizer D), And a phosphorus stabilizer of the following formula (5) is added.

（但し、上式中、ｎは１１〜１４の整数を表す）

(In the above formula, n represents an integer of 11 to 14)

  In carrying out the present invention, it is preferable that the thermoplastic resin described above is a polyolefin resin.

  By applying the configuration of the present invention, it is possible to reduce deterioration of the thermoplastic resin constituting the fiber at the interface between the photocatalyst particles and the fiber constituting the fabric. For this reason, since the photocatalyst carrying sheet is less deteriorated with time, such as dropping of the photocatalyst particles and a reduction in sheet strength, it is possible to provide an excellent photocatalyst carrying sheet having a deodorizing ability that is sustainable over a long period of time.

  Hereinafter, preferred embodiments for implementing the present invention will be described in detail. As described above, the main feature of the present invention is that, in the photocatalyst-carrying sheet made of a fabric in which photocatalyst particles are carried on the surface layer of the constituent fiber made of a thermoplastic resin at least on the surface, the fiber constituting the sheet has a predetermined stability. It is to contain an agent.

  Such a stabilizer should just be added to the thermoplastic resin part which contacts a photocatalyst particle in a sheet | seat, ie, the surface part to which the said particle | grain and fiber adhere. Therefore, as disclosed in Patent Document 3, the fibers constituting the fabric may be composed of a single resin component. For the purpose of avoiding thread breakage when the photocatalyst particles are fixed, for example, a core is used. More preferably, it is in the form of a sheath-type composite fiber. When such a composite fiber is employed, a stabilizer may be added to at least the thermoplastic resin constituting the sheath portion for the purpose of effectively preventing deterioration during use of the sheet.

  Among these stabilizers, hindered phenol stabilizers such as stabilizer D are generally called primary antioxidants and have radical scavenging as a main function. On the other hand, phosphorus-based stabilizers such as stabilizer E are called secondary antioxidants and, together with conventionally used sulfur-based stabilizers, are chained following radical generation that occurs early in the oxidation reaction. The main function is the decomposition of hydroperoxides. In addition, hindered amine stabilizers such as stabilizer A and stabilizer B and hydroxylamine stabilizers such as stabilizer C are both of these primary antioxidants and secondary antioxidants. It is supposed to have a function. By using these various stabilizers in combination, an extremely high antioxidant function can be expected, and the antioxidant function by the stabilizer is only in the portion of the surface layer of the constituent fiber that contacts the photocatalyst particles. Therefore, it is considered that only deterioration of the fabric can be effectively avoided without inhibiting various functions of the photocatalyst particles.

  As disclosed in Patent Document 3, a polyolefin resin, a polyester resin, a polyamide resin, or the like can be used as a thermoplastic resin that is a target for addition of these stabilizers and constitutes the above-described sheet fabric. Further, when the composite fiber is composed of a combination of composite fibers made of two or more different resins, the copolymer polyester / polyester, copolymer polypropylene / polypropylene, polypropylene / polyamide, polyethylene / polypropylene, polypropylene / Examples include polyester, polyethylene / polyester, and the like. When combining such a plurality of resins, the thermoplastic resin involved in the fixation with the photocatalyst may be selected from the combination having a relatively low melting point or softening point (shown comprehensively as the melting point). However, the melting point of the thermoplastic resin constituting the sheath part is more preferably at least 20 ° C. or higher, more preferably 50 ° C. or higher, compared to the melting point constituting the core part. In addition, from the combination with the stabilizer mentioned later and the fixing temperature of photocatalyst particles, as a fabric constituting the sheet of the present invention, as a thermoplastic resin constituting a sheath corresponding to the fiber surface, polyethylene, polypropylene It is preferable to use a polyolefin resin.

  Further, as photocatalyst particles suitable for use in the present invention, rutile type, anatase type or brookite type titanium oxide, zinc oxide, vanadium oxide, tungsten oxide, iron oxide, cadmium sulfide, gallium phosphide, barium titanate, titanate Known compounds that generate active oxygen by light of various wavelengths, such as strontium, can be used. In particular, the above-described titanium oxide that is stable to light and excellent in redox power is suitable.

  Next, the stabilizer of the present invention will be described in detail. In the present invention, the stabilizer A [N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis- (butyl) represented by the following formula (1) is used for the thermoplastic resin described above. -(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine]

Stabilizer B of the following formula (2) [polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol],

（但し、上式中、ｎは１１〜１４の整数を表す）
並びに下記式（３）に示す安定化剤Ｃ［Ｎ，Ｎ−ジステアリルヒドロキシルアミン］、

(In the above formula, n represents an integer of 11 to 14)
And stabilizer C [N, N-distearylhydroxylamine] represented by the following formula (3):

Furthermore, stabilizer D [pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] represented by the following formula (4):

And a stabilizer E [Tris (2,4-di-tert-butylphenyl) phosphite] represented by the following formula (5) is added.

  The addition ratio of the five kinds of stabilizers shown here is as follows: Stabilizer A: Stabilizer B: Stabilizer C: Stabilizer D: Stabilizer E = 1: 0 with respect to the thermoplastic resin described above. It is preferable that the ratio range is 1: 0.2: 0.1: 0.1 to 1: 0.1: 5: 5: 20. Moreover, it is a suitable addition ratio of these 5 types of stabilizers, Comprising: Content of 100-5000 ppm with respect to the weight of the thermoplastic resin which comprises at least surface layer of a constituent fiber, More preferably, content of 500-5000 ppm Is preferable. When the above-mentioned range of the preferred content exceeds the above-mentioned five kinds of stabilizers, thread breakage may occur during spinning, and when the stabilizer is less than the preferred content, There exists a possibility that the effect of a stabilizer may reduce. Among these stabilizers, a stabilizer in which stabilizer A and stabilizer B are mixed at a weight ratio of 9: 1 (hereinafter referred to as stabilizer AB) is “CHIMASSORB 119FL” ( KIMASORB 119 EF: The following is a trade name of the original language), and the stabilizer C is a trade name of “FS 042” (FS 042: the original language is described hereafter), and the stabilizer D is The product name of “IRGANOX 1010” (Irganox 1010: described in the original language only), and the stabilizer E is the product name of “IRGAFOS 168” (Irgaphos 168: described in the original language only). Available from Specialty Chemicals. A mixture of this stabilizer AB and stabilizer C in a weight ratio of 1: 1 is a product name of “IRGASTAB FS210FF” (Irgastab F210 F: hereinafter only described in the original language), Ciba Specialty -Available from Chemicals.

  Hereinafter, as examples disclosing preferred embodiments of the present invention, photocatalyst-carrying sheets in which various stabilizers are applied to the fibers constituting the fabric were produced, the results of verifying the deodorization efficiency, and the respective sheets at that time The result of evaluating the deterioration state of will be described. The following examples will be described with reference to predetermined shapes, numerical conditions, arrangement relationships, etc. to such an extent that the present invention can be easily understood, but these specific conditions are merely examples, and the present invention However, the present invention is not limited to these, and any suitable design changes and modifications can be made.

(Example)
First, a commercially available polypropylene resin (melting point: 167 ° C.) to which 1000 ppm of “IRGAFOS 168” (trade name; Stabilizer E, manufactured by Ciba Specialty Chemicals), which is a phosphorus stabilizer, is added, and hindered at 400 ppm. A commercially available polyethylene resin (melting point 135) containing “IRGANOX 1010” (trade name; Stabilizer D, manufactured by Ciba Specialty Chemicals Co., Ltd.) and 600 ppm “IRGAFOS 168” (same as above), which are phenolic stabilizers. In addition, 1500 ppm of “IRGASTAB FS210FF” (trade name; mixture of stabilizer AB and stabilizer C) manufactured by Ciba Specialty Chemicals Co., Ltd., which is a commercially available resin stabilizer, Fine polypropylene resin is used for the core and polyethylene resin is used for the sheath. Fibers were prepared by spinning 1.7 dtex core-sheath type adhesive fibers and cutting them to a fiber length of 5 mm. Next, a web was formed from the fibers by a known wet papermaking technique, and the entangling points were heated and bonded at 135 ° C. to prepare a fabric having an areal density of 60 g / m ² .

Subsequently, “ST-01” (trade name, manufactured by Ishihara Sangyo Co., Ltd.) is used as photocatalyst particles, and the technology of Patent Document 3 described above, that is, the particles preliminarily heated to 250 ° C., are heated at a high temperature. After spraying on the above-mentioned fabric and allowing to cool, the particles not fixed to the fiber surface were removed. In this way, a sheet sample according to an example having an areal density of 66 g / m ² in which 6 g / m ² of photocatalyst particles were fixed to the fiber surface was obtained.

(Comparative Example 1)
The two types of resins used in the examples, that is, the polypropylene resin constituting the core portion contains only 1000 ppm of the phosphorus stabilizer E, and the polyethylene resin constituting the sheath portion is 400 ppm of hindered phenol type. Using a mixture in which Stabilizer D and 600 ppm Stabilizer E were mixed and added, spinning was performed in the same manner as described above, and then cut to 5 mm to prepare a core-sheath type adhesive fiber for wet papermaking. A comparative example having the same surface density by applying the above-described powder fixing technique after producing a fabric by the same web forming process as in the examples except for the blending form of the stabilizer. A sheet sample according to 1 was obtained.

(Comparative Example 2)
For the fabric used in Comparative Example 1, composite photocatalyst particles “Mask Melon Photocatalyst” corresponding to the technique of Patent Document 2 (made by Taihei Chemical Sangyo Co., Ltd., porous silica having a particle diameter of 2 μm was formed into titanium oxide particles. using a film formation), we apply the same technique as in example was a sheet sample composite photocatalyst particles 6 g / m ² is according to Comparative example 2 of surface density 66 g / m ² which is fixed on the fiber surface.

(Comparative Example 3)
For the fabrics used in Comparative Example 1 and Comparative Example 2, “Boncoat AN-258” (trade name, manufactured by Dainippon Ink & Chemicals, Inc.), which is a commercially available acrylic copolymer binder emulsion, was used. A sheet sample according to Comparative Example 3 having a surface density of 78 g / m ² containing 6 g / m ^{2 of} the photocatalyst particles used in the above and 12 g / m ² as the solid content of the binder was used.

  The configurations specific to each of these four types of sheet samples are summarized in Table 1 below. In the same table, the name of the stabilizer added to the surface layer of the constituent fiber in the “fiber stabilizer” column, and the product name or form name of each photocatalyst particle described above in the “photocatalyst configuration” column. In the “adhesion means” column, “Particle heating” is shown when the technique of Patent Document 3 described above is applied, and “Binder” is the case where it is adhered and fixed with a binder.

Then, the result of having confirmed the deodorizing function among the evaluation methods with respect to a series of samples mentioned above is demonstrated. First, each sample is cut into 4 × 10 cm, and each sample is put into a glass container having a capacity of 600 cm ³ . The glass container in this state was blown with air at a temperature of 25 ° C. containing 100 ppm of acetaldehyde and a relative humidity of 40% for about 1 hour to purge the inside of the container and then sealed. Thereafter, in order to activate each photocatalyst particle, ultraviolet light having a wavelength of 365 nm was irradiated under the condition of an illuminance of 1 mW / cm ² , and degradation attenuation from the initial acetaldehyde concentration in the glass container was reduced to two levels of 20 minutes and 60 minutes. The evaluation time was measured by gas chromatography. For this result, the initial aldehyde concentration of 100 ppm was taken as 100, and the relative proportion of the residual concentration at each evaluation time was calculated as deodorization efficiency (%).

In addition to this deodorization test, the above-mentioned series of samples were converted to the xenon fade meter “FAL-25AXU-HC” (Suga A continuous exposure test was conducted under the conditions of a black panel temperature of 60 ° C. and a relative humidity of 50% for a maximum of 500 hours, an irradiation wavelength of 300 to 700 nm, and an illuminance of 35 mW / cm ² , depending on the test machine (trade name). did. After this exposure, each sample was placed on a black sheet, and the amount of photocatalyst particles dropped off by hand was visually observed to evaluate the dropout state of the photocatalyst particles in the following four stages.
◎: No dropout ○: Slight dropout is observed △: Dropout is observed ×: Significant dropout is observed

  Furthermore, in order to confirm the influence on the deterioration caused by the photocatalyst particles for each sample that has undergone such an evaluation test, in accordance with JIS L1096 “General Textile Test Method”, a tensile stretch type tester “Tensilon UCT-500” ( (Orientec Co., Ltd., product name) was stretched at a constant speed of 100 mm / min, and the maximum tensile strength was measured. In addition, as an evaluation index of deterioration, the tensile strength of each sample before the exposure test described above was set as 100, and a relative ratio with the tensile strength after exposure was calculated as a strength maintenance ratio (%). The evaluation results for these series of samples are shown in Table 2 below.

As can be understood from Table 2, the deodorization efficiency was determined in the Examples having substantially no component covering the surface of the photocatalyst particles, and Comparative Example 2 in which Comparative Example 1 was coated with silica, and Comparative Example in which a binder was coated. Compared to 3, it was confirmed to be superior. In addition, in the examples where the present invention was applied to both the dropout state and the strength maintenance rate that were evaluated as indicators of deterioration of the fibers constituting the fabric, significant differences appeared due to exposure for 350 hours or more compared to Comparative Examples 1 to 3. It was. From these evaluation results, it was confirmed that, by applying the present invention, deterioration to the fibers constituting the fabric can be effectively avoided while maintaining the deodorization efficiency.

Claims (2)

In a photocatalyst carrying sheet comprising a fabric having photocatalyst particles carried on a surface layer of a constituent fiber comprising at least a surface of a thermoplastic resin, the thermoplastic resin constituting the surface layer of the constituent fiber is represented by the following formulas (1) and (2 ), A hindered amine stabilizer of the following formula (3), a hindered phenol stabilizer of the following formula (4), and a phosphorus stabilizer of the following formula (5): Is added to the photocatalyst-carrying sheet.

(In the above formula, n represents an integer of 11 to 14)

The photocatalyst carrying sheet according to claim 1, wherein the thermoplastic resin is a polyolefin resin.