JP3963541B2 - Solar irradiation type air cleaning sheet and air purification method - Google Patents
Solar irradiation type air cleaning sheet and air purification method Download PDFInfo
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- JP3963541B2 JP3963541B2 JP30938897A JP30938897A JP3963541B2 JP 3963541 B2 JP3963541 B2 JP 3963541B2 JP 30938897 A JP30938897 A JP 30938897A JP 30938897 A JP30938897 A JP 30938897A JP 3963541 B2 JP3963541 B2 JP 3963541B2
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- Disinfection, Sterilisation Or Deodorisation Of Air (AREA)
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Description
【0001】
【発明の属する技術分野】
本発明は太陽光照射式の空気清浄用シート及びその空気清浄用シートを使用した空気の浄化方法に関し、特に、自動車の車内の脱臭に有用なものである。
【0002】
【従来の技術】
酸化物半導体である酸化チタン等の光触媒微粒子にバンドギャップ以上のエネルギ−を有する光を照射すると、励起により電子及び正孔が発生され、表面に近接した有機物や微生物が酸化により分解され、無機酸化物においては、最終酸化物にまで酸化されるに至る。
そこで、この光触媒微粒子をバインダ−で担持させた光触媒体に室内空気を接触させ、空気中の臭気性成分を分解して防臭乃至は空気浄化等を行うことが提案されている。この場合、光触媒微粒子を励起(活性化)させるための紫外線源として、太陽光を利用するケ−スとブラックライト等の紫外線発生器を利用するケ−スとがあるが、太陽光に曝される室内の空気浄化には、太陽光を利用することが便利である。
【0003】
上記光触媒微粒子を支持体に担持させるには、通常、光触媒微粒子をバインダ−を介して支持体に固着する方法が用いられており、このバインダ−には、活性化された光触媒微粒子で分解劣化されることのない安定性が要求される。
そこで、多くの先行技術が提示されており、例えば、バインダ−として、シリコ−ン系ポリマ−やビニルエ−テル−フルオロオレフィンコポリマ−やビニルエステル−フルオロオレフィンコポリマ−等のフッ素系ポリマ−を使用することが提案されている(特開平7−171408号)。
また、上記の空気浄化が光触媒体表面での接触反応によるためにその接触面積を可及的に広くすることが要求され、例えば、シ−ト状の光触媒体を間隙を隔てて積層したり、筒状の光触媒体を集束し、その間隙を空気通路とすることが提案されている(特開平7−251028号)。
【0004】
【発明が解決しようとする課題】
自動車においては、新車の場合、内装材からの揮発性ガスに起因する、所謂新車臭が嫌われ、また、使用中の車の場合、内装材やエアコン内部等に吸着した煙草臭が問題とされている。
従来、自動車の室内の脱臭には、活性炭、ゼオライト、シリカゲル、アルミナ等の吸着剤を主成分とする脱臭材が用いられているが、脱臭材の寿命が短く、相当に頻繁な取替えが必要とされ厄介である。
そこで、上記の光触媒体によって煙草臭を脱臭することが提案されているが(特開平7−251028号)、従来の光触媒体では、単位体積当りの空気接触面積が小さく、上記したように、シ−ト状の光触媒体を間隙を隔てて積層したり、筒状の光触媒体を集束し、その間隙を空気通路とすることが必要であり、かかる間隙構造では、その間隙に空気を流通させるためにフアン等が必要とされ、設備費のコストアップが避けられない。
【0005】
また、光触媒体の活性化に太陽光を利用する場合、光触媒体の配設が窓の近傍に制限され、従って設置スペ−スが必然的に限定される。例えば、自動車の場合、フロントガラスとバックミラ−との間やリヤウィンドウ近傍で、かつ視界を実質上妨げないスペ−スに限られ、利用できるスペ−スはたかだか200mm×200mm程度の垂直平面積の範囲内である。しかしながら、従来の光触媒体では、かかる限られたスペ−スで太陽光の照射下、車内を満足に脱臭することは困難である。
【0006】
そこで、本発明者は、自動車内の脱臭を、太陽光利用のもとで光触媒体により行うことを可能にするべく、鋭意検討した結果、ポリテトラフルオロエチレン粉末と光触媒微粒子とのディスパ−ジョンを塗布し、この塗布層を焼成して得た光触媒層が著しく優れた脱臭性能を呈し、前記の小さな設置スペ−スでも車内を効果的に脱臭できることを知った。この高い脱臭性能の原因を解明するために、その光触媒層の組織を顕微鏡で観察したところ、光触媒微粒子と樹脂との間に空気層が存在し、この空気層が繋がって連通路を形成していることを知った。この光触媒層において、光触媒微粒子とポリテトラフルオロエチレン樹脂との界面に空隙が形成される理由は、ポリテトラフルオロエチレンと光触媒酸化チタン微粒子との熱収縮率の著しい差とポリテトラフルオロエチレンの非接着性にあり、焼成加熱の冷却時、その界面に大なる熱収縮応力が発生し、界面の非接着性のためにその大なる引張り応力で界面剥離が生じることによると推定される。
【0007】
従来、光触媒体の製造方法として、ビニルエ−テル−フルオロオレフィンコポリマ−やビニルエステル−フルオロオレフィンコポリマ−等のフッ素系ポリマ−とイソシアネ−ト系硬化剤等の架橋剤と光触媒微粒子との溶剤溶液を支持体上に塗布し、この塗布層を架橋反応で硬化させること(特開平7−171408号)やポリテトラフルオロエチレン粒子と二酸化チタンと活性炭との混合物をシ−ト状に圧延すること(特開平6−3156号)が公知であるが、これらでは光触媒微粒子と樹脂との界面に収縮応力を発生させるような過程がなく、その界面での空隙発生が到底期待できない。
【0008】
本発明の目的は、上記検討結果の知見に基づき、自動車の室内を光触媒体で太陽光を利用し、運転者等の視界に支障を来すことなく満足に脱臭できるようにする太陽光照射式空気清浄用エレメント及び空気の浄化方法を提供することにある。
【0009】
【課題を解決するための手段】
本発明に係る太陽光照射式空気清浄用シートは、ポリテトラフルオロエチレン粉末と光触媒微粒子とを含有するディスパージョンが支持基材上に塗布・焼成されてポリテトラフルオロエチレン粉末が焼結されてなる多孔光触媒層を有し、ポリテトラフルオロエチレン粉末と光触媒微粒子との間のこれら両者の熱膨張収縮率の差に基づく前記焼成時の界面剥離で前記多孔光触媒層の空隙率が7%以上とされていることを特徴とする構成であり、活性炭、ゼオライト、または銅カルボキシルメチルセルロ−スの一種または二種以上を主成分とする脱臭シ−トを積層することができる。
本発明に係る空気の浄化方法は、これらの太陽光照射式空気清浄用シートを室内に配設し、太陽光を照射することを特徴とする構成である。
【0010】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図1は本発明に係る空気清浄用シートAの断面図を示している。
図1において、1は支持基材である。2は支持基材1上に設けた光触媒層であり、焼結されたポリテトラフルオロエチレン粉末の焼成層内に光触媒微粒子が分散され、樹脂と光触媒微粒子との間に微小空隙が形成され、焼結されたポリテトラフルオロエチレン粉末間の間隙が上記空気層に繋がって多間隙連通組織となっている。
上記ポリテトラフルオロエチレン樹脂と光触媒微粒子との間の空隙の厚みは、数ナノメ−タ〜数ミクロンの微細間隙であり、ポリテトラフルオロエチレンの疎水性のために、水等の通過は生じないが、空気は充分に流出入され得る。
【0011】
本発明に係る空気清浄用シートを製造するには、ポリテトラフルオロエチレン粉末と光触媒微粒子とを含有したディスパ−ジョンを支持基材に塗布し、加熱により塗布層中の溶媒を蒸発除去し、更に加熱焼成(加熱温度は330℃以上)によりポリテトラフルオロエチレン粒子間を焼結する。この焼結後の冷却時、ポリテトラフルオロエチレン樹脂の光触媒微粒子よりも大なる熱収縮及びポリテトラフルオロエチレン樹脂の光触媒微粒子に対する非融着性のために、光触媒微粒子とポリテトラフルオロエチレン樹脂との間に空気層が形成される。
また、焼成時でのポリテトラフルオロエチレン粉末の溶融粘度が高く(10ポアズ以上)流動せずに粒形状が保持され、かつ焼成が無加圧で行われるから、焼結されたポリテトラフルオロエチレン粉末間に間隙が充分に残存される。
従って、光触媒層は通気性の多間隙組織となる。
上記ポリテトラフルオロエチレン粉末の粒径は、0.1〜1μm、光触媒微粒子の粒径は200nm以下、好ましくは50nm以下である。
上記光触媒層の空隙率は7%以上、好ましくは10%以上とされる。この空隙率xは、光触媒層の真比重をρ、光触媒層の体積vの重量をwとすれば、
x=1−〔w/(vρ)〕
で与えられる。空隙率7%未満では、多間隙組織による空気と光触媒微粒子との接触度向上効果が低く、後述の比較例からも明らかなように自動車の室内の脱臭を満足に行い難い。ただし、機械的強度上30%以下とすることが好ましい。
また、光触媒層の厚さは3μm〜30μmとすることが好ましい。3μm未満では、光触媒層の体積が少なく脱臭性能が低くなり、30μmを越えるとガス拡散効率が低下し必要以上に厚い層厚になってしまう。
上記ディスパ−ジョンの光触媒微粒子配合量が多すぎると、ポリテトラフルオロエチレンによる光触媒微粒子間の結着強度が不充分となるので、光触媒微粒子の含有率は5〜60%とすることが好ましい。
【0012】
上記光触媒微粒子には、優れた光触媒活性を呈するアナタ−ゼ型酸化チタン微粒子を使用することが好ましい。また、光触媒微粒子の活性を高めるために、アルカリ金属イオンを担持させることができる。
上記支持基材には、焼成時の加熱によっても変形等を生じない耐熱性を有するものが使用され、例えば、アルミニウム,ステンレス等の金属箔やセラミックス板,ガラス板等の無機質板、ポリイミド,ポリテトラフルオロエチレン等の耐熱性プラスチックフィルムやポリテトラフルオロエチレン等の耐熱性プラスチックを含浸したガラス繊維やポリアミド繊維の織物やガラス繊維,セラミックス繊維,金属繊維,炭素繊維の単独または混合物のフエルト状物やガラス繊維,セラミックス繊維,金属繊維,炭素繊維の単独または混合物の網状物等を使用できる。
上記支持基材へのディスパ−ジョンの塗布には、ロ−ルコ−タで塗布する方法、支持基材をディスパ−ジョン中に浸漬して引き上げる方法、ディスパ−ジョンをスプレ−する方法、ディスパ−ジョンを刷毛塗する方法、ディスパ−ジョンを流延する方法等を使用できる。
上記ディスパ−ジョンの濃度は、塗布方法に応じて設定されるが、通常40%〜60%とされる。ディスパ−ジョンには、焼成層の空隙率をアップするための添加剤、強度を向上するための添加剤、更に焼成温度に耐え得るガス吸着剤を適宜添加することも可能である。
【0013】
本発明に係る空気清浄用シートにおいては、光触媒微粒子と樹脂バインダ−との間に空隙が存在し、この空隙を通じて空気が拡散流通するから、空気が光触媒微粒子の外表面にほぼ全面で接触して通過し、空気中の脱臭性成分が活性化光触媒微粒子で効率よく酸化脱臭される。
また、光触媒微粒子を担持しているポリテトラフルオロエチレンが難分解性であるから、樹脂バインダ−を崩壊無く長期にわたり安定に保持でき、かつ、光触媒微粒子を樹脂層の空隙を介して包み込んであるから、光触媒微粒子を長期にわたり安定に担持できる。
従って、空気中の脱臭性成分を長期にわたり効率よく酸化脱臭できる。
本発明に係る空気清浄用シートは、矩形、楕円形等の平板形状でその両端にフック等の留め具を取付けて使用でき、表面積を大きくするために、図2に示すようにブリ−ツ加工やハニカム加工して使用することもできる。図2において、3はフックを示している。
また、活性炭、ゼオライト、または銅カルボキシルメチルセルロ−スの一種または二種以上を主成分とする脱臭シ−トと積層して使用することもできる。
【0014】
本発明に係る空気清浄用シートは自動車の室内の脱臭(新車臭の脱臭、煙草臭の脱臭)に好適に使用でき、図3に示すように、空気清浄用シートAを自動車のフロントガラス41とバックミラ−42との間に運転手の視界を実質上妨げない寸法で配設したり、または、リヤウィンドウ43の近傍に乗客の視界を実質上妨げない寸法で配設し、太陽光線の照射で空気清浄用シートAの光触媒層を活性化して室内を脱臭することができる。
【0015】
【実施例】
〔実施例1〕
ディスパ−ジョンには光触媒酸化チタン微粒子(粒径7nm,比重3.84)の含有量40重量%のポリテトラフルオロエチレン粉末(粒径0.3μm,比重2.20)の水分散液を使用し、支持基材には厚み60μmのアルミニウム箔を使用した。このアルミニウム箔をディスパ−ジョンに浸漬し、引上げて100℃で乾燥したうえで390℃×2分で焼成して、光触媒層の空隙率が12.2%,厚さが7μmのシ−ト状光触媒体を得た。
このシ−ト状光触媒体を10cm×100cmに裁断し、10cm×10cmの外郭寸法のブリ−ツに加工し、両端にフックを取付て空気清浄用シートとした。
この空気清浄用エレメントを新車の乗用車(2000ccクラスのセダン型)のフロントガラスとバックミラ−との間に配設し日光が当る屋外に駐車して脱臭を行った。
空気清浄用シートを配設した後、5時間で新車臭が消臭した。3日目に空気清浄用シートを外したところ、一昼夜経過で再び新車臭が感知されたため、再度空気清浄用シートを配設したところ、再配設後5時間で新車臭が消え、以後新車臭は感知されなかった。
【0016】
〔実施例2〕
支持基材に厚さ0.6mm,坪量30g/m2の炭素繊維フェルトを使用した以外、実施例1と同様にしてシ−ト状光触媒体を得、このシ−ト状光触媒体に、銅カルボキシメチルセルロ−スを主成分とする脱臭シ−ト(興人社製クリ−ンスカイ)を積層し、これを10cm×100cmに裁断し、10cm×10cmの外郭寸法のブリ−ツに加工し、両端にフックを取付て空気清浄用シートとした。
この空気清浄用シートを、煙草臭が車の内装材やエアコン内部等に吸着している乗用車(2000ccクラスのセダン型)のフロントガラスとバックミラ−との間に配設し日光が当る屋外に駐車して脱臭を行った。
空気清浄用シートを配設した後、6時間経過以降は煙草臭が消え、以後煙草臭の吸着物からの脱離による恒久的な臭いは完全に消臭した。
【0017】
〔比較例1〕
実施例1に対し、光触媒層の空隙率が3.1%,厚さが7μmのシ−ト状光触媒体を得、他は実施例1と同様にして空気清浄用シートを製作した。
実施例1と同様にして新車臭の脱臭を試みたところ、満足できる脱臭は行えなかった。
〔比較例2〕
実施例1に対し、水ディスパ−ジョン中のポリテトラフルオロエチレンを溶融粘度が10ポアズのパ−フルオロアルキルビニルエ−テル−テトラフルオロエチレン共重合体に置換した以外、実施例1と同じとした。光触媒層の気孔率は1%であった。
実施例1と同様にして新車臭の脱臭を試みたところ、満足できる脱臭は行えなかった。
【0018】
このように比較例2が実施例1に較べ脱臭性能に劣るのは、パ−フルオロアルキルビニルエ−テル−テトラフルオロエチレン共重合体が光触媒微粒子によく加熱融着し、光触媒微粒子の表面の大部分がパ−フルオロアルキルビニルエ−テル−テトラフルオロエチレン共重合体で覆われること、パ−フルオロアルキルビニルエ−テル−テトラフルオロエチレン共重合体の溶融粘度が低く焼成時に粉末形態を保持し難く、焼結粉末間に間隙が残存し難いこと等によると推定される。
【0019】
【発明の効果】
本発明に係る空気清浄用シートにおいては、光触媒微粒子とバインダ−樹脂との間に微細空隙が存在し、その空隙を経て外部の空気が光触媒微粒子のほぼ全面に接触して流通するから、その空気中脱臭成分に対する活性光触媒微粒子の酸化脱臭効率を向上できる。また、光触媒微粒子が樹脂バインダ−内に抱き込まれ、かつ樹脂自体が難分解性であるから、光触媒微粒子を安定に担持できる。
従って、比較的に小さな外郭寸法にて長期にわたり脱臭でき、自動車のフロントガラスとバックミラ−との間やリヤウィンドウの近傍に実質上視界を阻害することなく配設し太陽光線照射による光触媒粒子の活性化で新車臭や煙草臭を満足に脱臭できる。
【図面の簡単な説明】
【図1】 本発明に係る太陽光照射式空気清浄用シートの断面図である。
【図2】 本発明に係る太陽光照射式空気清浄用シートの一例を示す図面である。
【図3】 本発明に係る太陽光照射式空気清浄用シートの使用状態を示す図面である。
【符号の説明】
1 支持基材
2 光触媒層
A 太陽光照射式空気清浄用シート [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solar irradiation type air cleaning sheet and an air purification method using the air cleaning sheet , and is particularly useful for deodorization in an automobile.
[0002]
[Prior art]
When photocatalyst fine particles such as titanium oxide, which is an oxide semiconductor, are irradiated with light having energy greater than the band gap, electrons and holes are generated by excitation, and organic substances and microorganisms close to the surface are decomposed by oxidation, resulting in inorganic oxidation. In the product, it is oxidized to the final oxide.
Therefore, it has been proposed that indoor air is brought into contact with a photocatalyst body carrying the photocatalyst fine particles with a binder to decompose odorous components in the air to perform deodorization or air purification. In this case, there are a case of using sunlight and a case of using an ultraviolet generator such as black light as an ultraviolet ray source for exciting (activating) the photocatalyst fine particles. It is convenient to use sunlight for purifying indoor air.
[0003]
In order to support the photocatalyst fine particles on the support, a method of fixing the photocatalyst fine particles to the support through a binder is usually used, and the binder is decomposed and degraded by the activated photocatalyst fine particles. Stability is required.
Therefore, many prior arts have been proposed. For example, a fluorine-based polymer such as a silicone-based polymer, a vinyl ether-fluoroolefin copolymer, or a vinyl ester-fluoroolefin copolymer is used as a binder. Has been proposed (Japanese Patent Laid-Open No. 7-171408).
In addition, since the air purification is based on a contact reaction on the surface of the photocatalyst, it is required to increase the contact area as much as possible, for example, a sheet-like photocatalyst is stacked with a gap, It has been proposed to condense a cylindrical photocatalyst body and use the gap as an air passage (Japanese Patent Laid-Open No. 7-251028).
[0004]
[Problems to be solved by the invention]
In automobiles, the so-called new car odor caused by the volatile gas from the interior material is disliked in the case of a new car. In the case of a car in use, the smell of tobacco adsorbed inside the interior material or the air conditioner is a problem. ing.
Conventionally, deodorizing materials mainly composed of an adsorbent such as activated carbon, zeolite, silica gel, and alumina have been used for deodorization of automobile interiors. However, the life of the deodorizing material is short and needs to be replaced with considerable frequency. It is awkward.
Thus, although it has been proposed to deodorize the cigarette odor with the above-mentioned photocatalyst (Japanese Patent Laid-Open No. 7-251028), the conventional photocatalyst has a small area of air contact per unit volume. -It is necessary to stack G-shaped photocatalysts with a gap, or to focus the cylindrical photocatalysts and use the gap as an air passage. In such a gap structure, air flows through the gap. In addition, a fan is required, and the cost of equipment is inevitably increased.
[0005]
In addition, when sunlight is used for the activation of the photocatalyst, the arrangement of the photocatalyst is limited to the vicinity of the window, and thus the installation space is necessarily limited. For example, in the case of an automobile, it is limited to a space between a windshield and a back mirror or in the vicinity of a rear window and that does not substantially obstruct the field of view, and the usable space is a vertical plane area of about 200 mm × 200 mm. Within range. However, with the conventional photocatalyst, it is difficult to satisfactorily deodorize the interior of the vehicle under the irradiation of sunlight with such a limited space.
[0006]
Therefore, as a result of intensive studies to make it possible to perform deodorization in an automobile with a photocatalyst under the use of sunlight, the present inventor has obtained a dispersion between polytetrafluoroethylene powder and photocatalyst fine particles. It was found that the photocatalyst layer obtained by applying and firing the applied layer exhibited a remarkably excellent deodorizing performance, and the inside of the vehicle can be effectively deodorized even in the small installation space. In order to elucidate the cause of this high deodorizing performance, when the structure of the photocatalyst layer was observed with a microscope, an air layer was present between the photocatalyst fine particles and the resin, and this air layer was connected to form a communication path. I knew that In this photocatalyst layer, voids are formed at the interface between the photocatalyst fine particles and the polytetrafluoroethylene resin. The reason is that there is a significant difference in thermal shrinkage between the polytetrafluoroethylene and the photocatalytic titanium oxide fine particles and the non-adhesion of the polytetrafluoroethylene. It is presumed that due to the non-adhesiveness of the interface, interfacial delamination occurs due to the large tensile stress due to the non-adhesiveness of the interface when cooling by firing heating.
[0007]
Conventionally, as a method for producing a photocatalyst, a solvent solution of a fluorine-based polymer such as vinyl ether-fluoroolefin copolymer or vinyl ester-fluoroolefin copolymer, a crosslinking agent such as an isocyanate curing agent, and photocatalyst fine particles is used. It is coated on a support and the coated layer is cured by a crosslinking reaction (Japanese Patent Laid-Open No. 7-171408), or a mixture of polytetrafluoroethylene particles, titanium dioxide and activated carbon is rolled into a sheet shape (special feature). No. 6-3156) is known, but in these, there is no process of generating shrinkage stress at the interface between the photocatalyst fine particles and the resin, and void generation at the interface cannot be expected at all.
[0008]
The object of the present invention is based on the findings of the above examination results, using sunlight with a photocatalyst in the interior of an automobile, and capable of deodorizing satisfactorily without disturbing the visibility of drivers and the like. An object of the present invention is to provide an air cleaning element and a method for purifying air.
[0009]
[Means for Solving the Problems]
The solar radiation-type air cleaning sheet according to the present invention is formed by applying a dispersion containing polytetrafluoroethylene powder and photocatalyst fine particles onto a support substrate and firing the resulting product to sinter the polytetrafluoroethylene powder. It has a porous photocatalyst layer, and the porosity of the porous photocatalyst layer is 7% or more due to interfacial delamination based on the difference in thermal expansion and shrinkage between the polytetrafluoroethylene powder and the photocatalyst fine particles. it has a structure, wherein, activated carbon, zeolites, or copper carboxymethyl cellulose - it is possible to stack the bets - deodorizing sheet mainly scan of one or more kinds.
The air purification method according to the present invention has a configuration characterized in that these solar light irradiation type air cleaning sheets are disposed indoors and irradiated with sunlight.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a sectional view of an air cleaning sheet A according to the present invention.
In FIG. 1, 1 is a support substrate. Reference numeral 2 denotes a photocatalyst layer provided on the support substrate 1, in which the photocatalyst fine particles are dispersed in the fired layer of the sintered polytetrafluoroethylene powder, and microvoids are formed between the resin and the photocatalyst fine particles. A gap between the joined polytetrafluoroethylene powders is connected to the air layer to form a multi-gap communication structure.
The thickness of the gap between the polytetrafluoroethylene resin and the photocatalyst fine particles is a fine gap of several nanometers to several microns, and the passage of water or the like does not occur due to the hydrophobicity of polytetrafluoroethylene. Air can flow in and out sufficiently.
[0011]
To produce an air cleaning sheet according to the present invention, a dispersion containing polytetrafluoroethylene powder and photocatalyst fine particles is applied to a support substrate, and the solvent in the coating layer is evaporated and removed by heating. The polytetrafluoroethylene particles are sintered by heating and baking (heating temperature is 330 ° C. or higher). Upon cooling after this sintering, the photocatalyst fine particles and the polytetrafluoroethylene resin are bonded to each other due to thermal contraction greater than that of the photocatalytic fine particles of the polytetrafluoroethylene resin and non-fusibility of the polytetrafluoroethylene resin to the photocatalytic fine particles. An air layer is formed between them.
In addition, since the polytetrafluoroethylene powder at the time of firing has a high melt viscosity (10 poise or more) and does not flow, the particle shape is maintained and the firing is performed without pressure. Sufficient gaps remain between the powders.
Therefore, the photocatalyst layer becomes a breathable multi-gap structure.
The particle diameter of the polytetrafluoroethylene powder is 0.1 to 1 μm, and the particle diameter of the photocatalyst fine particles is 200 nm or less, preferably 50 nm or less.
The porosity of the photocatalyst layer is 7% or more, preferably 10% or more. The porosity x is expressed as follows: ρ is the true specific gravity of the photocatalyst layer, and w is the weight of the volume v of the photocatalyst layer.
x = 1- [w / (vρ)]
Given in. When the porosity is less than 7%, the effect of improving the contact degree between the air and the photocatalyst fine particles due to the multi-pore structure is low, and it is difficult to satisfactorily deodorize the interior of the automobile, as will be apparent from the comparative examples described later. However, the mechanical strength is preferably 30% or less.
Moreover, it is preferable that the thickness of a photocatalyst layer shall be 3 micrometers-30 micrometers. If it is less than 3 μm, the volume of the photocatalyst layer is small and the deodorizing performance is low, and if it exceeds 30 μm, the gas diffusion efficiency is lowered and the layer thickness becomes thicker than necessary.
If the amount of the photocatalyst fine particles in the dispersion is too large, the binding strength between the photocatalyst fine particles by polytetrafluoroethylene becomes insufficient, so the content of the photocatalyst fine particles is preferably 5 to 60%.
[0012]
As the photocatalyst fine particles, it is preferable to use anatase-type titanium oxide fine particles exhibiting excellent photocatalytic activity. Further, alkali metal ions can be supported in order to increase the activity of the photocatalyst fine particles.
As the support substrate, a material having heat resistance that does not deform even when heated during firing is used. For example, metal foil such as aluminum and stainless steel, ceramic plate, inorganic plate such as glass plate, polyimide, A glass fiber or polyamide fiber fabric impregnated with a heat-resistant plastic film such as tetrafluoroethylene or a heat-resistant plastic such as polytetrafluoroethylene, or a felt-like material made of glass fiber, ceramic fiber, metal fiber, or carbon fiber alone or in combination. Glass fibers, ceramic fibers, metal fibers, carbon fibers alone or a mixture of nets can be used.
For applying the dispersion to the support substrate, a method of applying with a roll coater, a method of immersing and lifting the support substrate in the dispersion, a method of spraying the dispersion, a disperser A method of brushing John, a method of casting disperse, and the like can be used.
The concentration of the dispersion is set according to the coating method, but is usually 40% to 60%. It is also possible to appropriately add an additive for increasing the porosity of the fired layer, an additive for improving the strength, and a gas adsorbent that can withstand the firing temperature to the dispersion.
[0013]
In the air cleaning sheet according to the present invention, there is a gap between the photocatalyst fine particles and the resin binder, and air diffuses and circulates through the gap, so that the air almost contacts the outer surface of the photocatalyst fine particles. Passing through, the deodorizing component in the air is efficiently oxidized and deodorized by the activated photocatalyst fine particles.
In addition, since polytetrafluoroethylene carrying the photocatalyst fine particles is hardly decomposable, the resin binder can be stably held for a long time without collapsing, and the photocatalyst fine particles are wrapped through the voids of the resin layer. The photocatalyst fine particles can be stably supported over a long period of time.
Therefore, the deodorizing component in the air can be efficiently oxidized and deodorized over a long period of time.
The air cleaning sheet according to the present invention has a flat plate shape such as a rectangle or an ellipse, and can be used with a fastener such as a hook attached to both ends thereof. In order to increase the surface area, as shown in FIG. It can also be used after being processed into a honeycomb. In FIG. 2, 3 indicates a hook.
Moreover, it can also be used by laminating | stacking with the deodorizing sheet | seat which has 1 type, or 2 or more types of activated carbon, a zeolite, or copper carboxyl methyl cellulose as a main component.
[0014]
The air cleaning sheet according to the present invention can be suitably used for deodorization in the interior of an automobile (deodorization of a new car odor, deodorization of cigarette odor). As shown in FIG. Between the
[0015]
【Example】
[Example 1]
For dispersion, an aqueous dispersion of polytetrafluoroethylene powder (particle size 0.3 μm, specific gravity 2.20) having a content of 40% by weight of photocatalytic titanium oxide fine particles (particle size 7 nm, specific gravity 3.84) is used. The supporting substrate was an aluminum foil having a thickness of 60 μm. This aluminum foil is immersed in a dispersion, pulled up, dried at 100 ° C., and then fired at 390 ° C. for 2 minutes. The photocatalytic layer has a porosity of 12.2% and a thickness of 7 μm. A photocatalyst was obtained.
This sheet-like photocatalyst was cut into 10 cm × 100 cm, processed into an outer dimension of 10 cm × 10 cm, and hooks were attached to both ends to form an air cleaning sheet .
This air cleaning element was disposed between the windshield and the back mirror of a new passenger car (2000 cc class sedan type), and deodorized by parking outdoors in sunlight.
The new car odor disappeared in 5 hours after the air cleaning sheet was installed. When the air cleaning seat was removed on the third day, a new car odor was detected again after a day and night. When the air cleaning seat was placed again, the new car odor disappeared 5 hours after the re-installation. Was not perceived.
[0016]
[Example 2]
A sheet-like photocatalyst was obtained in the same manner as in Example 1 except that a carbon fiber felt having a thickness of 0.6 mm and a basis weight of 30 g / m 2 was used as the support substrate. A deodorizing sheet (clean sky made by Kojin Co., Ltd.) mainly composed of copper carboxymethyl cellulose is laminated, and this is cut into 10 cm x 100 cm and processed into a 10 cm x 10 cm outer dimension bleat. Then, hooks were attached to both ends to obtain an air cleaning sheet .
This air-cleaning seat is placed between the windshield and the back mirror of a passenger car (2000cc class sedan type) that has a cigarette odor adsorbed in the interior of the car or inside the air conditioner. And deodorized.
After the air cleaning sheet was installed, the cigarette odor disappeared after 6 hours, and the permanent odor due to the detachment of the cigarette odor from the adsorbent was completely eliminated.
[0017]
[Comparative Example 1]
A sheet-like photocatalyst having a photocatalyst layer porosity of 3.1% and a thickness of 7 μm was obtained with respect to Example 1, and an air cleaning sheet was produced in the same manner as in Example 1.
When an attempt was made to deodorize a new car odor in the same manner as in Example 1, satisfactory deodorization could not be performed.
[Comparative Example 2]
Example 1 was the same as Example 1 except that polytetrafluoroethylene in the water dispersion was replaced with a perfluoroalkylvinyl ether-tetrafluoroethylene copolymer having a melt viscosity of 10 poise. . The porosity of the photocatalyst layer was 1%.
When an attempt was made to deodorize a new car odor in the same manner as in Example 1, satisfactory deodorization could not be performed.
[0018]
Thus, Comparative Example 2 is inferior in deodorization performance compared to Example 1 because the perfluoroalkylvinyl ether-tetrafluoroethylene copolymer is well heat-sealed to the photocatalyst fine particles, and the surface of the photocatalyst fine particles is large. The part is covered with a perfluoroalkyl vinyl ether-tetrafluoroethylene copolymer, and the melt viscosity of the perfluoroalkyl vinyl ether-tetrafluoroethylene copolymer is low, making it difficult to maintain the powder form during firing. It is presumed that this is because gaps hardly remain between the sintered powders.
[0019]
【The invention's effect】
In the air cleaning sheet according to the present invention, there are fine voids between the photocatalyst fine particles and the binder-resin, and external air flows through the voids in contact with almost the entire surface of the photocatalyst fine particles. The oxidative deodorization efficiency of the active photocatalyst fine particles for the medium deodorizing component can be improved. Further, since the photocatalyst fine particles are embraced in the resin binder and the resin itself is hardly decomposable, the photocatalyst fine particles can be stably supported.
Therefore, it can be deodorized for a long time with a relatively small outer dimension, and is disposed between the windshield and the back mirror of an automobile or in the vicinity of the rear window without substantially impeding the visibility, and the activity of the photocatalyst particles by the irradiation of sunlight. The new car odor and cigarette odor can be deodorized satisfactorily.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a solar light irradiation type air cleaning sheet according to the present invention.
FIG. 2 is a view showing an example of a solar irradiation type air cleaning sheet according to the present invention.
FIG. 3 is a view showing a usage state of a solar irradiation type air cleaning sheet according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Support base material 2 Photocatalyst layer A Solar irradiation type air cleaning sheet
Claims (5)
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JP30938897A JP3963541B2 (en) | 1997-10-23 | 1997-10-23 | Solar irradiation type air cleaning sheet and air purification method |
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JP4033552B2 (en) * | 1998-04-22 | 2008-01-16 | 株式会社エクォス・リサーチ | Air purifying filter and air purifier using the same |
JP2002011312A (en) * | 2000-06-29 | 2002-01-15 | Nitto Denko Corp | Incinerator exhaust gas treatment filter and its production method |
US6884399B2 (en) | 2001-07-30 | 2005-04-26 | Carrier Corporation | Modular photocatalytic air purifier |
JP5332099B2 (en) * | 2006-11-20 | 2013-11-06 | 日産自動車株式会社 | Photocatalytic system for automobile |
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JP2574840B2 (en) * | 1988-01-22 | 1997-01-22 | 株式会社日立製作所 | Deodorizing device |
JP3592727B2 (en) * | 1992-05-11 | 2004-11-24 | 日本電池株式会社 | Photocatalyst |
JP3526592B2 (en) * | 1993-06-24 | 2004-05-17 | 株式会社デンソー | Method for producing deodorant |
AU676299B2 (en) * | 1993-06-28 | 1997-03-06 | Akira Fujishima | Photocatalyst composite and process for producing the same |
JPH07251028A (en) * | 1994-03-15 | 1995-10-03 | Mitsubishi Electric Corp | Apparatus for deodorizing tobacco smell |
JPH08150197A (en) * | 1994-09-29 | 1996-06-11 | Toto Ltd | Member equipped with deodorizing function |
JP3728331B2 (en) * | 1995-03-16 | 2005-12-21 | 株式会社アイワ | Air purification sheet and method for producing the same |
JPH09119893A (en) * | 1995-10-24 | 1997-05-06 | Nippon Paint Co Ltd | Method for accelerated weathering test of fluororesin-based paint |
JPH09249871A (en) * | 1996-03-14 | 1997-09-22 | Toli Corp Ltd | Stainproofing and deodorizing structure and interior material utilizing the same structure |
JPH09256217A (en) * | 1996-03-25 | 1997-09-30 | Nitto Denko Corp | Polytetrafluoroethylene fiber and its production |
WO1998026115A1 (en) * | 1996-12-13 | 1998-06-18 | Daikin Industries, Ltd. | Fibrous materials of fluororesins and deodorant and antibacterial fabrics made by using the same |
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