[發明所欲解決之問題]一般而言，磷酸鹽系玻璃之熱膨脹係數較高，於成形後之徐冷步驟中容易產生裂縫或破裂。又，該裂縫或破裂亦容易於熱加工時例如加熱母材玻璃板而進行薄板成形之所謂再曳引成形時產生。又，磷酸鹽玻璃存在耐候性(尤其是耐水性)較低之問題。另一方面，若為了提昇耐候性而進行成分調整，則有玻璃化變得不穩定之情形。鑒於以上情況，本發明之目的在於提供一種具有所需之近紅外吸收特性，並且耐候性及玻璃化穩定性優異，而且於成形後之徐冷步驟中或熱加工時不易產生裂縫或破裂之近紅外線吸收濾光器用玻璃。[解決問題之技術手段]本發明之近紅外線吸收濾光器用玻璃之特徵在於：以質量%計，含有65～80%之P2
O5
、1～10%之SiO2
、7～25%之Al2
O3
、0.1～14%之R2
O(R係選自Li、Na及K中之至少1種)、1.5～20%之R'O(R係選自Mg、Ca、Sr、Ba及Zn中之至少1種)、1.5～20%之MgO、1～15%之CuO，且以質量比計P2
O5
/SiO2
為10～80。本發明者進行努力研究，結果發現藉由包含具有上述組成之磷酸鹽玻璃之近紅外線吸收濾光器用玻璃，可消除上述問題。再者，本發明之近紅外線吸收濾光器用玻璃具有由於含有相對較多之P2
O5
，故而因CuO離子所引起之近紅外線吸收較高之特徵。若P2
O5
之含量變多，則耐候性容易降低，但於本發明之玻璃中，藉由如上所述般限制P2
O5
/SiO2
之比率，抑制耐候性之降低。再者，「P2
O5
/SiO2
」意指P2
O5
含量與SiO2
含量之比。本發明之近紅外線吸收濾光器用玻璃較佳為以質量比計，P2
O5
/R2
O為9.2以上。如此，可提昇玻璃化穩定性。本發明之近紅外線吸收濾光器用玻璃較佳為以質量%計，Cr2
O3
為1%以下，且NiO為1%以下。Cr2
O3
及NiO係降低可見光範圍之透光率之成分。因此，藉由如上所述般限制該等之含量，容易獲得可見光範圍內之透光率優異之玻璃。本發明之近紅外線吸收濾光器用玻璃較佳為30～300℃之範圍內之熱膨脹係數為110×10-7
/℃以下。如此，可抑制成形時之裂縫或破裂之產生。本發明之近紅外線吸收濾光器用玻璃較佳為結晶析出溫度為1300℃以下。如此，成為玻璃化穩定性優異之玻璃。再者，若結晶析出溫度較低，則相應地可降低熔融溫度。若熔融溫度高溫化，則Cu離子被還原而近紅外吸收特性(分光特性)降低，並且可見光範圍內之透光率容易降低。因此，藉由降低熔融溫度，可抑制該問題之產生。於本發明中，「結晶析出溫度」係指於降低均質之熔融玻璃之溫度並保持18小時之時開始析出結晶的溫度。本發明之近紅外線吸收濾光器用玻璃較佳為於透光率為50%之波長λ50
成為615 nm之厚度下，波長1200 nm下之透光率為30%以下，且波長500 nm下之透光率為84%以上。本發明之近紅外線吸收濾光器之特徵在於包含上述近紅外線吸收濾光器用玻璃。本發明之近紅外線吸收濾光器較佳為厚度為0.1～1 mm。[發明之效果]本發明之近紅外線吸收濾光器用玻璃具有所需之近紅外吸收特性，並且耐候性及玻璃化穩定性優異。又，由於在成形後之徐冷步驟中不易產生裂縫或破裂，故而可穩定地生產薄板狀玻璃。[Problems to be Solved by the Invention] In general, phosphate glass has a high coefficient of thermal expansion, and cracks or cracks are likely to occur during the cold cooling step after forming. Further, the crack or crack is also likely to occur during so-called re-drawing molding in which hot-working, for example, heating of a base material glass plate to form a thin plate. Further, phosphate glass has a problem that weather resistance (especially water resistance) is low. On the other hand, if component adjustment is performed in order to improve weather resistance, vitrification may become unstable. In view of the above circumstances, an object of the present invention is to provide a near-infrared absorption property which is required, and which is excellent in weather resistance and vitrification stability, and which is less likely to be cracked or cracked during a cold step or a hot process after forming. Glass for infrared absorption filter. [Means for Solving the Problem] The glass for a near-infrared absorption filter of the present invention is characterized by containing 65 to 80% of P 2 O 5 , 1 to 10% of SiO 2 , and 7 to 25% by mass%. Al 2 O 3 , 0.1 to 14% R 2 O (R is selected from at least one of Li, Na, and K), and 1.5 to 20% of R′O (R is selected from the group consisting of Mg, Ca, Sr, and Ba). And at least one of Zn), 1.5 to 20% of MgO, and 1 to 15% of CuO, and P 2 O 5 /SiO 2 is 10 to 80 by mass ratio. As a result of intensive studies, the inventors have found that the above problem can be eliminated by using a glass for a near-infrared absorption filter comprising phosphate glass having the above composition. Further, the glass for a near-infrared absorption filter of the present invention has a feature that the near-infrared absorption due to CuO ions is high due to the relatively large amount of P 2 O 5 . When the content of P 2 O 5 is increased, the weather resistance is liable to lower. However, in the glass of the present invention, the ratio of P 2 O 5 /SiO 2 is restricted as described above, and the deterioration of weather resistance is suppressed. Further, "P 2 O 5 /SiO 2 " means the ratio of the P 2 O 5 content to the SiO 2 content. The glass for the near-infrared absorption filter of the present invention is preferably 9.2 or more in terms of mass ratio of P 2 O 5 /R 2 O. In this way, the vitrification stability can be improved. The glass for a near-infrared absorption filter of the present invention preferably has a Cr 2 O 3 content of 1% or less and a NiO of 1% or less by mass%. Cr 2 O 3 and NiO are components which lower the light transmittance in the visible light range. Therefore, by limiting the content of these as described above, it is easy to obtain a glass having excellent light transmittance in the visible light range. The glass for a near-infrared absorption filter of the present invention preferably has a thermal expansion coefficient in the range of 30 to 300 ° C of 110 × 10 -7 / ° C or less. Thus, the occurrence of cracks or cracks during molding can be suppressed. The glass for a near-infrared absorption filter of the present invention preferably has a crystallization temperature of 1300 ° C or less. In this way, it is a glass excellent in vitrification stability. Further, if the crystallization temperature is low, the melting temperature can be lowered accordingly. When the melting temperature is increased, the Cu ions are reduced and the near-infrared absorption characteristics (spectral characteristics) are lowered, and the light transmittance in the visible light range is liable to lower. Therefore, by reducing the melting temperature, the occurrence of this problem can be suppressed. In the present invention, the "crystallization precipitation temperature" refers to a temperature at which precipitation of crystals starts when the temperature of the homogeneous molten glass is lowered and maintained for 18 hours. The glass for the near-infrared absorption filter of the present invention preferably has a light transmittance of 615 nm at a wavelength of λ 50 of 50%, a light transmittance of 30% or less at a wavelength of 1200 nm, and a wavelength of 500 nm. The light transmittance is 84% or more. The near-infrared absorption filter of the present invention is characterized by comprising the above-mentioned glass for a near-infrared absorption filter. The near-infrared absorption filter of the present invention preferably has a thickness of 0.1 to 1 mm. [Effect of the Invention] The glass for a near-infrared absorption filter of the present invention has desired near-infrared absorption characteristics and is excellent in weather resistance and glass transition stability. Further, since cracks or cracks are less likely to occur in the cold cooling step after the forming, the thin plate glass can be stably produced.
本發明之近紅外線吸收濾光器用玻璃之特徵在於：以質量%計，含有65～80%之P2
O5
、1～10%之SiO2
、7～25%之Al2
O3
、0.1～14%之R2
O(R係選自Li、Na及K中之至少1種)、1.5～20%之R'O(R係選自Mg、Ca、Sr、Ba及Zn中之至少1種)、1.5～20%之MgO、1～15%之CuO，且以質量比計P2
O5
/SiO2
為10～80。以下說明如此規定各成分之含量範圍之原因。P2
O5
係用以形成玻璃骨架之必需成分，有降低結晶析出溫度之效果。P2
O5
之含量為65～80%，較佳為68～80%、70～80%(但是，不包含70%)、71～78%、尤其是71～76%。若P2
O5
之含量過少，則有玻璃化變得不穩定之傾向。另一方面，若P2
O5
之含量過多，則有耐候性降低、或熱膨脹係數變大之傾向。SiO2
係強化玻璃骨架之成分。又，有降低熱膨脹係數，或提昇耐候性之效果。SiO2
之含量為1～10%，較佳為1.8～10%、2.2～10%、2.2～8%、尤其是2.5～6%。若SiO2
之含量過少，則難以獲得上述效果。另一方面，若SiO2
之含量過多，則反之耐候性容易降低。又，有玻璃化變得不穩定之傾向。P2
O5
/SiO2
(質量比)為10～80，較佳為10～70、10～50、10～31、尤其是10～29。如此，容易獲得耐候性提昇及結晶析出溫度降低之效果。Al2
O3
係提昇耐候性，又，降低熱膨脹係數之成分。Al2
O3
之含量為7～25%，較佳為8～23%、尤其是10～20%。若Al2
O3
之含量過少，則難以獲得上述效果。另一方面，若Al2
O3
之含量過多，則玻璃化容易變得不穩定。又，有可見光範圍透過率降低之傾向。R2
O(R係選自Li、Na及K中之至少1種)係提高玻璃化之穩定性之成分。又，有切斷鏈狀之P2
O5
網絡而增加Cu離子之氧配位數之效果。Cu離子之近紅外線吸收特性根據氧配位數而提高，故而藉由含有R2
O，容易降低近紅外區域中之透光率。其中，R2
O亦為明顯提高熱膨脹係數，又，降低耐候性之成分。進而，若其含量過多，則容易析出鹼性磷酸系結晶。鑒於以上情況，R2
O之含量為0.1～14%，較佳為1～14%、1.5～12%、2～10%，尤其是2～8%。R2
O之各成分之含量之較佳之範圍如下所述。於R2
O中，Na2
O係對玻璃化之穩定尤其有效之成分。Na2
O之含量較佳為0.1～14%、1～14%、2～12%，尤其是5～9%。若Na2
O含量過少，則難以獲得上述效果。另一方面，若Na2
O之含量過多，則有析出鈉磷酸系結晶，反之玻璃化變得不穩定之傾向。又，耐候性容易降低。Li2
O及K2
O有提高熔融性，降低熔融溫度之效果，但另一方面，使玻璃化不穩定，耐候性亦大幅降低之成分。因此，Li2
O及K2
O之含量較佳為分別為0～7%、分別為0～5%、尤其是實質上不含有。再者，於本說明書中，「實質上不含有」意指不刻意地作為原料而含有，並不排除不可避免之雜質。更客觀而言，意指未達0.1%。再者，P2
O5
/R2
O(質量比)較佳為9.2以上、尤其是10以上。如此，可抑制鹼性磷酸系結晶之析出。R'O(R'係選自Mg、Ca、Sr、Ba及Zn中之至少1種)係使玻璃化穩定，或抑制分相之成分。又，亦有提昇耐候性之效果。R'O之含量為1.5～20%，尤佳為2～12%。若R'O之含量過少，則難以獲得上述效果。另一方面，若R'O之含量過多，則有反之玻璃化變得不穩定之傾向。再者，R'O之各成分之含量之較佳之範圍如下所述。於R'O中，MgO係對耐候性之提昇尤其有效之成分。MgO之含量較佳為1.5～20%、2～15%，尤其是4～9%。若MgO含量過少，則難以獲得上述效果。另一方面，若MgO之含量過多，則有析出鎂磷酸系結晶，反之玻璃化變得不穩定之傾向。CaO、SrO、BaO、ZnO係對玻璃化之穩定較為有效，但若其含量過多，則有反之玻璃化變得不穩定之傾向。因此，該等成分之含量較佳為分別為0～10%、尤其是分別為0～5%。CuO係用以吸收近紅外線之必需成分。CuO之含量為1～15%，較佳為1～10%，尤其是3～9%。若CuO之含量過少，則難以獲得所需之近紅外線吸收特性。另一方面，若CuO之含量過多，則有紫外～可見光範圍之透光率降低之傾向。又，有玻璃化變得不穩定之傾向。再者，近紅外線吸收濾光器用玻璃之近紅外線吸收量依賴於CuO含量及玻璃之厚度。因此，較佳為根據近紅外線吸收濾光器用玻璃之厚度而適當調整CuO含量。例如，為了使玻璃薄型化，並且達成所需之近紅外線吸收特性，較佳為使CuO之含量較多。於本發明之近紅外線吸收濾光器用玻璃中，除上述成分以外，亦可含有下述成分。CeO2
及Sb2
O3
有抑制Cu2 ＋
離子之還原，提昇近紅外線吸收特性之效果。但是，若該等成分之含量過多，則有玻璃化變得不穩定之傾向。因此，CeO2
及Sb2
O3
之含量較佳為以合計量計為0～0.5%、0～0.3%，尤其是實質上不含有。Nb2
O5
係提昇耐候性之成分。Nb2
O5
之含量較佳為0～3%、尤其是0～2%。若Nb2
O5
之含量過多，則有熔融性降低而熔融溫度變高之傾向。其結果為，Cu2 ＋
離子容易被還原，難以獲得所需之分光特性。Y2
O3
、La2
O3
及Ta2
O5
係使玻璃化穩定之成分。Y2
O3
、La2
O3
及Ta2
O5
之含量較佳為分別為0～3%、尤其是分別為0～2%。若Y2
O3
、La2
O3
及Ta2
O5
之含量過多，則於成形時容易失透。又，有折射率變高而表面反射變大，可見光範圍之透光率降低之傾向。B2
O3
係使玻璃化不穩定之成分，又，降低可見之透過率，故而其含量較佳為3%以下、2%以下，尤其是0.5%以下。TiO2
、WO3
、MnO2
、CeO2
、Cr2
O3
及NiO係明顯降低可見光範圍之透光率之成分。因此，該等成分之含量較佳為分別為1%以下、尤其是實質上不含有。Bi2
O3
有還原Cu離子而使玻璃呈現金屬色，結果為對分光特性造成不良影響之傾向，故而較佳為實質上不含有。Nd2
O3
、V2
O5
由於對分光特性造成不良影響，故而較佳為實質上不含有。考慮到對人體之影響，較佳為實質上不含有Cl成分。又，SnO、SnO2
、Ag2
O由於可能會對Cu元素之價數造成影響，故而較佳為實質上不含有。Fe2
O3
由於吸收可見光(例如500 nm)，故而其含量較佳為設為0.01%以下。Dy2
O3
及Ho2
O3
由於會導致原料成本之高漲，故而較佳為實質上不含有。再者，若於原料中包含較多之U成分或Th成分作為雜質，則自玻璃釋放α射線。因此，於可見度修正濾光器或顏色調整濾光器之用途中，有因α射線而對CCD或CMOS之信號造成障礙之虞。因此，本發明之近紅外線吸收濾光器用玻璃中之U及Th之含量較佳為分別為1 ppm以下、100 ppb以下，尤其是20 ppb以下。又，自本發明之近紅外線吸收濾光器用玻璃釋放之α射線量較佳為1.0 c/cm2
・h以下。本發明之近紅外線吸收濾光器用玻璃之30～300℃之範圍內的熱膨脹係數較佳為110×10-7
/℃以下、105×10-7
/℃以下，尤其是100×10-7
/℃以下。若熱膨脹係數過大，則於成形時容易產生裂縫或破裂。本發明之近紅外線吸收濾光器用玻璃之結晶析出溫度較佳為1300℃以下、尤其是1250℃以下。若結晶析出溫度過高，則玻璃化之穩定性容易降低。又，由於必須使熔融溫度較高，故而Cu離子被還原而近紅外吸收特性降低，並且可見光範圍內之透光率容易降低。本發明之近紅外線吸收濾光器用玻璃可維持可見光範圍內之較高之透光率，並且充分截斷近紅外區之光。具體而言，較佳為於透光率為50%之波長λ50
成為615 nm之厚度下，波長1200 nm下之透光率為30%以下(進而為18%以下)，且波長500 nm下之透光率為84%以上(進而為86%以上)。包含本發明之近紅外線吸收濾光器用玻璃之近紅外線吸收濾光器之厚度較佳為0.1～1 mm、尤其是0.3～0.9 mm。若厚度過小，則容易破損。另一方面，若厚度過大，則有難以進行光學裝置之薄型化或輕量化之傾向。本發明之近紅外線吸收濾光器用玻璃可以如下方式製造。首先，以成為所需之組成之方式製備原料批料。其次，加熱原料批料而獲得熔融玻璃。熔融溫度較佳為1100～1350℃，更佳為1100～1300℃，進而較佳為1100～1250℃。若熔融溫度過低，則難以獲得均質之玻璃。另一方面，若熔融溫度過高，則Cu2 ＋
離子容易被還原，難以獲得所需之分光特性。於將熔融玻璃成形並徐冷後，視需要實施切削、研磨等後加工，藉此獲得本發明之近紅外線吸收濾光器用玻璃。此處，藉由採用將熔融玻璃直接成形之方法(例如下拉法、滾壓法、直接加壓法、浮式法等)、或一面加熱母材玻璃一面進行延伸之方法(再曳引法)，可高效率地製作厚度較小之近紅外線吸收濾光器用玻璃。再者，如上所述，本發明之近紅外線吸收濾光器用玻璃由於熱膨脹係數較低，故而即便藉由上述方法成形亦可抑制裂縫或破裂。[實施例]以下，基於實施例詳細地說明本發明，但本發明並不限定於該等實施例。表1及2表示本發明之實施例(No.1～10)及比較例(No.11～14)。[表1]
[表2]
各試樣係以如下方式製作。首先，將以成為表中記載之玻璃組成之方式調製之原料批料投入至鉑坩堝中，於1200～1300℃下熔融為均質。作為原料，使用偏磷酸鹽、氧化物、硫酸鹽、硝酸鹽、碳酸鹽等。其次，將熔融玻璃流出至碳板上，進行冷卻固化，然後進行退火而製作試樣。對所獲得之試樣測定或評價結晶析出溫度、透光率、熱膨脹係數、耐候性。將結果示於表1及2。又，將No.3之試樣之透光率曲線示於圖1。結晶析出溫度係以如下方式進行測定。於鉑坩堝中加熱試樣50 g而獲得熔融液，於1000～1350℃之範圍內每50℃分別保持18小時。其後，將玻璃熔融液流出至碳板上，將可見結晶之溫度設為結晶析出溫度。透光率係以如下方式測定。將試樣切斷為25 mm×30 mm之大小，以成為表中記載之厚度之方式將兩面進行鏡面研磨加工。對加工後之試樣，使用光譜分析裝置(島津製作所製造之UV3100)測定各波長下之透光率。熱膨脹係數係使用膨脹計測定30～300℃之範圍內之值。耐候性係藉由不飽和壓力鍋試驗而進行。具體而言，製作25 mm×30 mm×0.5 mm之大小之兩面經鏡面研磨之試樣，觀察於溫度120℃、濕度80%之環境下將該試樣靜置8小時後之試樣表面。將藉由目測及顯微鏡觀察(×100)於試樣表面未見變化者設為「A」，將目測未見試樣表面之變化，但顯微鏡觀察可見變化者設為「B」，將目測可確認到試樣表面之變化者設為「C」而作為評價。根據表1及圖1可知，作為實施例之No.1～10之試樣具有所需之分光特性，並且熱膨脹係數較低為100×10-7
/℃以下，耐候性良好。另一方面，根據表2可知，作為比較例之No.11及13之試樣於耐候性試驗中於表面形成異質層，為C評價。又，No.11之試樣之熱膨脹係數較高為150×10-7
/℃。No.12及14之試樣未進行玻璃化。The glass for a near-infrared absorption filter of the present invention is characterized by containing 65 to 80% of P 2 O 5 , 1 to 10% of SiO 2 , 7 to 25% of Al 2 O 3 , 0.1 to 1% by mass. 14% of R 2 O (R is at least one selected from the group consisting of Li, Na, and K) and 1.5 to 20% of R'O (R is selected from at least one of Mg, Ca, Sr, Ba, and Zn). And 1.5 to 20% of MgO and 1 to 15% of CuO, and P 2 O 5 /SiO 2 is 10 to 80 by mass ratio. The reason why the content range of each component is specified as described below will be described below. P 2 O 5 is an essential component for forming a glass skeleton and has an effect of lowering the crystallization temperature. The content of P 2 O 5 is 65 to 80%, preferably 68 to 80%, 70 to 80% (however, 70%), 71 to 78%, and especially 71 to 76%. When the content of P 2 O 5 is too small, the vitrification tends to be unstable. On the other hand, when the content of P 2 O 5 is too large, the weather resistance is lowered or the thermal expansion coefficient tends to be large. The SiO 2 is a component of the tempered glass skeleton. Moreover, there is an effect of lowering the coefficient of thermal expansion or improving the weather resistance. The content of SiO 2 is from 1 to 10%, preferably from 1.8 to 10%, from 2.2 to 10%, from 2.2 to 8%, especially from 2.5 to 6%. If the content of SiO 2 is too small, it is difficult to obtain the above effects. On the other hand, when the content of SiO 2 is too large, the weather resistance is liable to lower. Moreover, there is a tendency that vitrification becomes unstable. P 2 O 5 /SiO 2 (mass ratio) is 10 to 80, preferably 10 to 70, 10 to 50, 10 to 31, particularly 10 to 29. Thus, the effect of improving weather resistance and lowering the crystallization temperature is easily obtained. The Al 2 O 3 system improves the weather resistance and, in turn, lowers the coefficient of thermal expansion. The content of Al 2 O 3 is 7 to 25%, preferably 8 to 23%, particularly 10 to 20%. If the content of Al 2 O 3 is too small, it is difficult to obtain the above effects. On the other hand, when the content of Al 2 O 3 is too large, vitrification tends to be unstable. Further, there is a tendency that the transmittance in the visible light range is lowered. R 2 O (R is at least one selected from the group consisting of Li, Na, and K) is a component that enhances the stability of vitrification. Further, there is an effect of cutting the chain-like P 2 O 5 network to increase the oxygen coordination number of Cu ions. Since the near-infrared absorption characteristic of Cu ions is increased in accordance with the oxygen coordination number, it is easy to reduce the light transmittance in the near-infrared region by containing R 2 O. Among them, R 2 O is also a component which significantly increases the coefficient of thermal expansion and reduces the weather resistance. Further, when the content is too large, alkaline phosphate crystals are easily precipitated. In view of the above, the content of R 2 O is from 0.1 to 14%, preferably from 1 to 14%, from 1.5 to 12%, from 2 to 10%, especially from 2 to 8%. The preferred range of the content of each component of R 2 O is as follows. Among R 2 O, Na 2 O is a component which is particularly effective for stabilizing vitrification. The content of Na 2 O is preferably from 0.1 to 14%, from 1 to 14%, from 2 to 12%, particularly from 5 to 9%. If the Na 2 O content is too small, it is difficult to obtain the above effects. On the other hand, when the content of Na 2 O is too large, sodium phosphate crystals are precipitated, and the vitrification tends to be unstable. Moreover, weather resistance is liable to lower. Li 2 O and K 2 O have an effect of improving the meltability and lowering the melting temperature, but on the other hand, they are unstable in vitrification and have a markedly lowered weather resistance. Therefore, the content of Li 2 O and K 2 O is preferably 0 to 7%, respectively 0 to 5%, and particularly not substantially contained. In addition, in the present specification, "substantially not contained" means that it is contained unintentionally as a raw material, and does not exclude unavoidable impurities. More objectively, it means less than 0.1%. Further, P 2 O 5 /R 2 O (mass ratio) is preferably 9.2 or more, particularly 10 or more. Thus, precipitation of an alkali phosphate crystal can be suppressed. R'O (R' is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) stabilizes vitrification or suppresses components of phase separation. In addition, there is also the effect of improving weather resistance. The content of R'O is from 1.5 to 20%, particularly preferably from 2 to 12%. If the content of R'O is too small, it is difficult to obtain the above effects. On the other hand, if the content of R'O is too large, the glass transition tends to be unstable. Further, a preferred range of the content of each component of R'O is as follows. Among R'O, MgO is a particularly effective ingredient for improving weather resistance. The content of MgO is preferably from 1.5 to 20%, from 2 to 15%, especially from 4 to 9%. If the MgO content is too small, it is difficult to obtain the above effects. On the other hand, when the content of MgO is too large, magnesium phosphate crystals are precipitated, and the vitrification tends to be unstable. The CaO, SrO, BaO, and ZnO systems are effective for stabilizing the vitrification. However, if the content is too large, the vitrification tends to be unstable. Therefore, the content of the components is preferably from 0 to 10%, particularly from 0 to 5%, respectively. CuO is used to absorb the essential components of near infrared rays. The content of CuO is from 1 to 15%, preferably from 1 to 10%, especially from 3 to 9%. If the content of CuO is too small, it is difficult to obtain the desired near-infrared absorption characteristics. On the other hand, when the content of CuO is too large, the light transmittance in the ultraviolet to visible light range tends to decrease. Moreover, there is a tendency that vitrification becomes unstable. Further, the near-infrared absorption amount of the glass for the near-infrared absorption filter depends on the CuO content and the thickness of the glass. Therefore, it is preferable to appropriately adjust the CuO content in accordance with the thickness of the glass for the near-infrared ray absorbing filter. For example, in order to make the glass thinner and to achieve the desired near-infrared absorption characteristics, it is preferred to have a large content of CuO. The glass for a near-infrared absorption filter of the present invention may contain the following components in addition to the above components. CeO 2 and Sb 2 O 3 have the effect of suppressing the reduction of Cu 2 + ions and improving the absorption characteristics of near infrared rays. However, if the content of these components is too large, vitrification tends to be unstable. Therefore, the content of CeO 2 and Sb 2 O 3 is preferably 0 to 0.5% and 0 to 0.3% in total, and in particular, substantially not contained. Nb 2 O 5 is a component that enhances weather resistance. The content of Nb 2 O 5 is preferably from 0 to 3%, particularly from 0 to 2%. When the content of Nb 2 O 5 is too large, the meltability is lowered and the melting temperature tends to be high. As a result, Cu 2 + ions are easily reduced, and it is difficult to obtain desired spectral characteristics. Y 2 O 3 , La 2 O 3 and Ta 2 O 5 are components which stabilize the vitrification. The content of Y 2 O 3 , La 2 O 3 and Ta 2 O 5 is preferably from 0 to 3%, particularly from 0 to 2%, respectively. When the content of Y 2 O 3 , La 2 O 3 and Ta 2 O 5 is too large, devitrification is likely to occur at the time of molding. Further, the refractive index becomes high and the surface reflection becomes large, and the light transmittance in the visible light range tends to decrease. The B 2 O 3 system is a component which makes the glassy unstable, and reduces the visible transmittance. Therefore, the content thereof is preferably 3% or less and 2% or less, particularly 0.5% or less. TiO 2 , WO 3 , MnO 2 , CeO 2 , Cr 2 O 3 and NiO are components which significantly reduce the light transmittance in the visible light range. Therefore, the content of the components is preferably 1% or less, and particularly not substantially. Bi 2 O 3 has a tendency to reduce the Cu ion and cause the glass to have a metallic color. As a result, it tends to adversely affect the spectral characteristics, and therefore it is preferably substantially not contained. Since Nd 2 O 3 and V 2 O 5 have an adverse effect on the spectral characteristics, they are preferably substantially not contained. In view of the influence on the human body, it is preferred that substantially no Cl component is contained. Further, since SnO, SnO 2 and Ag 2 O may affect the valence of the Cu element, it is preferably substantially not contained. Since Fe 2 O 3 absorbs visible light (for example, 500 nm), the content thereof is preferably set to 0.01% or less. Since Dy 2 O 3 and Ho 2 O 3 cause a high cost of raw materials, they are preferably substantially not contained. Further, when a large amount of the U component or the Th component is contained as an impurity in the raw material, the α ray is released from the glass. Therefore, in the use of the visibility correction filter or the color adjustment filter, there is a problem that the signal of the CCD or CMOS is hindered by the alpha ray. Therefore, the content of U and Th in the glass for a near-infrared absorption filter of the present invention is preferably 1 ppm or less and 100 ppb or less, particularly 20 ppb or less. Moreover, the amount of α-rays released from the glass for the near-infrared absorption filter of the present invention is preferably 1.0 c/cm 2 ·h or less. The coefficient of thermal expansion in the range of 30 to 300 ° C of the glass for the near-infrared absorption filter of the present invention is preferably 110 × 10 -7 / ° C or less, 105 × 10 -7 / ° C or less, especially 100 × 10 -7 / Below °C. If the coefficient of thermal expansion is too large, cracks or cracks are likely to occur during molding. The crystallization temperature of the glass for the near-infrared absorption filter of the present invention is preferably 1300 ° C or lower, particularly 1250 ° C or lower. When the crystallization temperature is too high, the stability of vitrification is liable to lower. Further, since the melting temperature must be made high, the Cu ions are reduced and the near-infrared absorption characteristics are lowered, and the light transmittance in the visible light range is liable to lower. The glass for the near-infrared absorption filter of the present invention can maintain a high light transmittance in the visible light range and sufficiently cut off the light in the near-infrared region. Specifically, the light transmittance is preferably in the wavelength becomes λ 50% at a thickness of 50 615 nm, the light transmittance at a wavelength of 1200 nm of 30% or less (and further 18% or less), and the wavelength at 500 nm The light transmittance is 84% or more (and further 86% or more). The thickness of the near-infrared absorption filter including the glass for a near-infrared absorption filter of the present invention is preferably 0.1 to 1 mm, particularly 0.3 to 0.9 mm. If the thickness is too small, it is easily broken. On the other hand, if the thickness is too large, it tends to be difficult to reduce the thickness and weight of the optical device. The glass for a near-infrared absorption filter of the present invention can be produced in the following manner. First, the raw material batch is prepared in such a manner as to become a desired composition. Next, the raw material batch is heated to obtain molten glass. The melting temperature is preferably from 1,100 to 1,350 ° C, more preferably from 1,100 to 1,300 ° C, still more preferably from 1,100 to 1,250 ° C. If the melting temperature is too low, it is difficult to obtain a homogeneous glass. On the other hand, if the melting temperature is too high, Cu 2 + ions are easily reduced, and it is difficult to obtain desired spectral characteristics. After the molten glass is molded and cold-cooled, post-processing such as cutting, polishing, or the like is performed as needed, whereby the glass for a near-infrared absorption filter of the present invention is obtained. Here, a method of directly forming a molten glass (for example, a down-draw method, a rolling method, a direct press method, a float method, or the like) or a method of stretching a base material glass while heating (re-drawing method) is employed. It is possible to efficiently produce a glass for a near-infrared absorption filter having a small thickness. Further, as described above, since the glass for a near-infrared absorption filter of the present invention has a low coefficient of thermal expansion, it can suppress cracks or cracks even if it is formed by the above method. [Examples] Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the examples. Tables 1 and 2 show examples (Nos. 1 to 10) and comparative examples (Nos. 11 to 14) of the present invention. [Table 1] [Table 2] Each sample was produced in the following manner. First, a raw material batch prepared in such a manner as to be a glass composition described in the table is put into a platinum crucible, and is melted at 1200 to 1300 ° C to be homogeneous. As a raw material, a metaphosphate, an oxide, a sulfate, a nitrate, a carbonate, etc. are used. Next, the molten glass was discharged onto a carbon plate, cooled and solidified, and then annealed to prepare a sample. The obtained sample was measured or evaluated for crystal precipitation temperature, light transmittance, thermal expansion coefficient, and weather resistance. The results are shown in Tables 1 and 2. Further, the light transmittance curve of the sample No. 3 is shown in Fig. 1. The crystallization temperature was measured in the following manner. 50 g of the sample was heated in a platinum crucible to obtain a melt, which was maintained at 50 ° C for 18 hours in the range of 1000 to 1350 ° C. Thereafter, the glass melt was discharged to the carbon plate, and the temperature of the visible crystal was set as the crystallization temperature. The light transmittance was measured in the following manner. The sample was cut into a size of 25 mm × 30 mm, and both surfaces were mirror-polished so as to have the thickness described in the table. The light transmittance at each wavelength was measured using a spectroscopic analyzer (UV3100 manufactured by Shimadzu Corporation). The coefficient of thermal expansion is a value measured in the range of 30 to 300 ° C using a dilatometer. Weatherability is carried out by an unsaturated pressure cooker test. Specifically, a mirror-polished sample having a size of 25 mm × 30 mm × 0.5 mm was prepared, and the surface of the sample was allowed to stand for 8 hours in an environment of a temperature of 120 ° C and a humidity of 80%. When the change was not observed on the surface of the sample by visual observation or microscopic observation (×100), the change in the surface of the sample was not observed by visual observation. However, the change in the microscope observation was set to "B", and the visual inspection was possible. It was confirmed that the change in the surface of the sample was "C". As can be seen from Table 1 and Fig. 1, the samples of Nos. 1 to 10 which are examples have the desired spectral characteristics, and the coefficient of thermal expansion is as low as 100 × 10 -7 / ° C or less, and the weather resistance is good. On the other hand, according to Table 2, the samples of Nos. 11 and 13 which are comparative examples formed a heterogeneous layer on the surface in the weather resistance test, and were evaluated as C. Further, the sample of No. 11 had a high coefficient of thermal expansion of 150 × 10 -7 / ° C. The samples No. 12 and 14 were not vitrified.