JPH11157868A - Lead-free heavy crown or especially heavy crown optical glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lead-free heavy crown or especially heavy crown optical glass having a refractive index nd of 1.60-1.65, an Abbe's number νd of 50-60, satisfactory meltability and workability, sufficient chemical resistance and high crystallization stability. SOLUTION: This glass has a compsn. consisting of, by weight on the oxide basis, 20-37% SiO2 , 8-20% B2 O3 , 43-55% BaO, 0.01-10% ZnO, 0-7% CaO, 0-7% MgO (CaO+MgO<=7% and BaO+ZnO+CaO+MgO<60%), 0.01-5% TiO2 , 0.01-7% ZrO2 , 0.1-10% Al2 O3 , 0-8% Na2 O, 0-8% K2 O (Na2 O+K2 O<=8%), 0 to <3% La2 O3 , 0-1% F<-> and 0-3% P2 O5 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to the present invention in the range of 1.60 to 1.6.
The present invention relates to a lead-free heavy crown or extra heavy crown optical glass having a refractive index n _{d of} 5 and an Abbe number v _{d of} 50 to 60.

[0002]

_2. Description of the Related Art In recent years, glass components PbO and As ₂ O ₃
Is harmful to the environment. Therefore, some optical equipment manufacturers have proposed PbO or As ₂ O ₃
Is switched to using only glass that does not contain. Thus, such glasses with their respective optical properties must be offered to the market. Eliminating PbO is also worth the effort to make light glass parts, ie low density glass.

[0003] However, usually, simply replacing lead oxide with one or more other components does not reproduce the desired optical and glass technical properties obtained with PbO. Instead, new developments or extensive changes in the glass composition are required. Numerous reports describing lead-free glasses having the above optical values have already been found in the patent literature. However, these glasses exhibit various disadvantages.

[0004] For example, German Patent Publication No. 1421877
And British Patent No. 996307 contain at least 3.3% by weight or 3% by weight of La for adjusting the optical state.
Glasses that must contain ₂ O ₃ are described. This makes the glass expensive and uneconomical for continuous manufacturing processes. La ₂ O ₃ partially extremely high
The same applies to the glasses described in JP-A-60-221338, which contain Y ₂ O ₃ (up to 20% by weight) in addition to the content (up to 52% by weight). This glass is partially B
₂ O ₃ content is very high (50% by weight or less) and Li
_The presence of ₂ O results in poor chemical resistance of the glass, which makes subsequent processing difficult and limits its use. In addition, since the devitrification resistance of the glass is reduced by Li ₂ O, glass defects due to crystals may occur particularly in a continuous manufacturing process. This is described in Japanese Patent Application Laid-Open Nos.
This also applies to the glass described in -119666. These glasses also require Li ₂ O.

The same applies to Gd ₂ O ₃ as for Y ₂ O ₃ . This expensive oxide significantly increases batch costs and, consequently, manufacturing costs. It is German Patent 226
It is an essential component of the glass described in 5703C2. The glass described in JP-A-5-17176 requires SrO. The glass contains this component in an amount up to 20% by weight. The effect of SrO on the optical properties is almost equivalent to the effect of BaO and CaO, and the latter component can be introduced into glass with a clearly cheaper raw material,
rO can be eliminated, which is advantageous for economical production.

[0006] The glasses described in DE-A 19 18 350 contain from 2 to 14.5% by weight of fluorine. If produced on an industrial scale with this high fluorine content, HF and Si
It takes labor for purification of exhaust gases containing F _4, becomes expensive. DE-A 220 2012 describes a TiO ₂ -free glass containing CeO ₂ and having a low SiO ₂ content in the above-mentioned optical state. It is stated to be used as a filter. This glass will show a tendency to discolor under UV irradiation. JP-A-62-70245 describes a glass suitable as a glass fiber core material. This glass is also Ti
Since it does not contain O ₂ , it may be said that it does not have sufficient chemical resistance and solarization resistance. In addition, TiO ₂
In the free state, it is almost impossible to adjust the combination of low Abbe number and high refractive index required for the glass in the heavy crown region in this glass region.

A glass containing neither TiO ₂ nor ZrO ₂ is disclosed in US Pat. No. 15,139,923 and JP-A-62-28743.
No. 3 and JP-A-3-93644. In particular, if the B ₂ O ₃ content is high (JP-A-3-93644:
40% by weight or less, JP-A-62-87433: 30% by weight or less), and ZrO ₂ -free glass has low chemical resistance. The heavy crown glass described in JP-A-6-107424 does not contain ZnO at all. Such ZnO-free glass of, ZrO ₂ content will not have good crystallization stability at 0.5-8 wt%. The same applies to ZnO-free 1-18 as described in British Patent No. 1132401.
The same is true for glasses containing weight% ZrO ₂ .

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to have a good refractive index n _d of 1.60 to 1.65, an Abbe number ν _d of 50 to 60, and good solubility and processability. An object of the present invention is to provide a lead-free heavy crown or extra heavy crown optical glass having sufficient chemical resistance and high crystallization stability.

[0009]

According to the present invention, there is provided, according to the present invention, the following composition based on oxides: _{20 to} 37% by weight of SiO _2, 8 to 20% by weight of B ₂ O ₃ , BaO 43 0 to 55% by weight, ZnO 0.01 to 10% by weight, CaO 0 to 7% by weight, MgO 0 to 7% by weight, provided that CaO + MgO 0 to 7% by weight, provided that BaO + ZnO + CaO + MgO <60% by weight, TiO ₂ 0.01 5 wt%, ZrO ₂ 0.01 to 7 wt%, Al ₂ O ₃ 0.1 to 10 wt%, Na ₂ O 0 to 8% by weight, K ₂ O 0 to 8 wt%, however, Na ₂ O + K ₂ O 0 to 8 _{wt%, La 2 O 3 0~ <} 3 ^wt%, F - 0 to 1 wt%, P ₂ O ₅ 0 to 3 wt%, have a conventional amount of fining agent, if necessary And a refractive index n _{d of} 1.60 to 1.65 and 50 to
A lead-free heavy crown or extra heavy crown optical glass having an Abbe number ν _{d of} 60 is provided.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The glass according to the invention contains ₂₀ to 37% by weight of the glass former SiO2. If the SiO ₂ content is lower than this range, glass formation becomes difficult. On the other hand, if the SiO ₂ content is higher than the above range, the melting temperature rises significantly, which may cause evaporation of other glass components. This glass is 8-20
It contains B ₂ O ₃ in a percentage by weight. This component significantly improves the _fusibility and does not adversely affect the coefficient of thermal expansion α _20/300 . The above minimum content guarantees sufficient fusibility of the glass. The maximum content described above must not be exceeded, since this has a negative effect on chemical resistance, in particular on alkali resistance.

Further, the glass of the present invention contains 43 to 55% by weight of BaO to obtain a desired Abbe number. Below this minimum content, the desired Abbe number cannot be obtained for this glass system. On the other hand, when the BaO content exceeds the upper limit, the tendency to devitrify greatly increases. The glass according to the invention has at least 0.01% by weight for stabilization against crystallization.
, The relatively high BaO content described above is not a problem. ZnO also improves the speck resistance of the glass.
The maximum content of ZnO is limited to 10% by weight. Otherwise, chemical resistance, especially acid resistance, is deteriorated.

For further stabilization against crystallization, the glasses according to the invention can furthermore contain up to 7% by weight each of CaO and MgO. In that case, CaO and MgO
Must not exceed 7% by weight. MgO and Ca
O is not only effective for suppressing crystallization, but also allows for a relatively high Abbe number with a relatively low refractive index. The total amount of the divalent oxides BaO, ZnO, MgO, and CaO is 6
It must be limited to less than 0% by weight. Otherwise, especially in the case of continuous production, glass defects occur due to the crystallization phenomenon.

[0013] For the acid resistance of the improvement, the glass of the present invention, include components ZrO ₂ in accordance with the present invention (0.01 to 7 wt%) and TiO ₂ (0.01 to 5 wt%). If the proportion of these components is higher than the above range, the fusibility and crystallization resistance deteriorate. Also, too high a TiO ₂ content results in undesirable yellowing. With the above amounts, TiO ₂ is more effective for obtaining the desired optical state, especially a relatively low refractive index and a relatively low Abbe number. Another essential component is Al ₂ O ₃ . This is a ratio of 0.1 to 10% by weight, which is also effective for improving acid resistance. If the content of this component is too high, the fusibility will be adversely affected.

The glass of the present invention may contain up to 1% by weight of fluorine. Particularly when the content of TiO ₂ and ZrO ₂ is high, fluorine is required to facilitate melting. Fluorine is effective for fine adjustment of refractive index and fining. Addition of more than 1% by weight of fluorine is undesirable. In that case, segregation and crystallization may occur, and exhaust gas purification for avoiding vapor harmful to the environment becomes extremely troublesome.

The glass according to the invention has a La ₂ content of less than 3% by weight.
O ₃ may be included. This also improves the chemical resistance. If the content is 3% by weight or more, the glass is difficult to melt.
Also, if the proportion of this expensive component is too high, the glass becomes unduly expensive. The La ₂ O ₃ component is suitable, especially if the refractive index is already high but a further increase in the refractive index is desired.

Further, the glass of the present invention can contain 3% by weight or less of P ₂ O ₅ . P ₂ O ₅ improves the fusibility of the glass and can neutralize the tendency to devitrify caused by fluorine in small amounts. However, if the proportion of P ₂ O ₅ is higher than this, the acid resistance decreases, and at the same time, the devitrification tendency increases again. In addition, the glass of the present invention contains 8% by weight or less of Na ₂ O and 8% by weight or less of K to improve fusibility.
₂ O may be included. Again, the total amount of these alkali oxides must not exceed 8% by weight. If the content of these components is higher than the above ratio, the transition temperature Tg
And the coefficient of thermal expansion α _20/300 is inhibited. Note that Li ₂ O is not included at all.

To improve glass quality, one or more known fining agents are added to the batch in conventional amounts to clarify the glass. Thereby, the glass has a particularly good internal glass quality with respect to defoaming and striae. A as fining agent
If instead of s ₂ O ₃ , for example, Sb ₂ O ₃ is used instead, which is possible without compromising the glass quality, the lead-free glass according to the invention is furthermore arsenic-free. 0.3% by weight or less of Sb ₂ O ₃ for clarification alone or in combination with the above-mentioned fluorine content, or 1% by weight or less of Cl ⁻ added as, for example, NaCl, BaCl _{2 in} non-fluoride glass. It is preferable to use them in combination. Sb ₂ O ₃ and F ^- or Sb ₂ O ₃ and Cl ^-
Is preferably at least 0.05% by weight.

A preferred group of heavy or extra heavy crown glasses of the present invention having the above optical state are glasses containing fluoride and lanthanum oxide in the following composition range (weight% based on oxide). SiO ₂ 20-37%
(Preferably 26 to 34%, particularly preferably 26 to 33%
_{%), B 2 O 3 11~20} % ( preferably 12 to 15
%), BaO 43-55% (preferably 43-52)
%), ZnO 0.1 to 10% (particularly preferably 0.1%
0-4%), CaO 0-7% (preferably 0-2%, particularly preferably CaO-free), MgO 0-7% (preferably 0-2%, particularly preferably MgO-free), provided that CaO + MgO 0- 7% and BaO + ZnO + C
aO + MgO <60%, TiO 2 0.01~5% ( preferably 0.01~3%), ZrO ₂ 0.05~7%
(Preferably 0.1-4%), Al ₂ O ₃ 0.1-1
0% (preferably _{0.5~7%), Na 2 O 0~8} %
(Preferably 0 to 2%, especially preferably Na ₂ O free), K ₂ O 0 to 8% (preferably 0-2%, particularly preferably K ₂ O-free), _{where, Na 2 O + K 2 O} 0
_{~8%, La 2 O 3 0.1~} <3%, F 0.05~
_{1%, P 2 O 5 0~3} %.

The presence of La ₂ O ₃ increases the refractive index. This is used when increasing the BaO content, especially for increasing the refractive index, is no longer appropriate for reasons discussed in BaO. Due to the presence of fluoride, this glass system used here to obtain the desired properties of the glass includes relatively large amounts of TiO ₂ and Zr
A glass containing O ₂ is obtained. In that case, the fusibility of the glass is not hindered or the crystallization phenomenon does not occur. The aforementioned concentration of TiO ₂ makes it possible to obtain a relatively high refractive index at a relatively low Abbe number, ie in this case to provide, in particular, a heavy crown glass. ZrO ₂ improves chemical resistance.

Among the preferred composition ranges mentioned above are two groups of heavy crown glasses which are particularly well-balanced and suitable for economical continuous production. Composition range (weight% based on oxide)
Is as follows. SiO ₂ 28-31%; B ₂ O ₃
13-14%; BaO 47-50%; ZnO 2
_{3%; TiO 2 0.1~0.3%;} ZrO 2 0.1
１1%; Al ₂ O ₃ 4 to 5%; La ₂ O ₃ 0.2 to
^{0.6%; F - 0.05~0.1%;} P 2 O 5 0~
3%. This glass has a refractive index n _{d of} 1.61 to 1.64.
And having an Abbe number [nu _d of 57 to 59.

SiO ₂ 32 to 34%; B ₂ O ₃ 13
１４14%; BaO 43-45%; ZnO 3-5%;
TiO ₂ 0.01-0.1%; ZrO ₂ 0.05-
0.3%; Al ₂ O ₃ 3-5%; La ₂ O ₃ 0.1
^{~0.4%; F - 0.8~1%;} P 2 O 5 0~3
%. This glass has a refractive index n _d of 1.60 to 1.62 and an Abbe number ν _{d of} 58 to 60.

Another preferred embodiment of the present invention is a heavy crown glass having a refractive index n _d of 1.60 to 1.63 and an Abbe number ν _d of 55 to 60. In this glass, F ^- is also La ₂ O
₃ can be excluded. In particular, by reducing the proportion of ZrO ₂ and TiO ₂ , non-fluoride can be obtained. The composition range of this preferred glass is as follows (wt% on oxide basis): SiO ₂ 31-37
_{%; B 2 O 3 8~14%} ; BaO 45~51%; Z
nO 0.01-4%; CaO 0-7%; MgO 0
7%; however, CaO + MgO 0 to 7% and BaO + Zn
O + CaO + MgO <60%; TiO ₂ 0.01 to
_{0.5%; ZrO 2 0.01~0.4%;} Al 2 O 3
Na ₂ O 0 to 1%; K ₂ O 0 to 2%; P
₂ O _{3 0~3%.} In this case, in a preferred embodiment, CaO,
Does not contain MgO, K ₂ O and P ₂ O ₅ .

Within the above range lies a particularly preferred range of glass compositions, the glasses being characterized by particularly good meltability and processability based on a balanced combination of glass components.
It has the following composition range (% by weight on oxide):
_{SiO 2 32~36%; B 2 O} 3 9~13%; Ba
O 45-50%; ZnO 0.01-3%; TiO ₂
0.01~0.4%; ZrO ₂ 0.01~0.3
_{%; Al 2 O 3 4~6%} ; Na 2 O 0~0.5%.
This also has a refractive index n _d of 1.60 to 1.63 and an Abbe number ν.
_d is 55-60 heavy crown glass.

Within the above composition ranges, there are a variety of suitable subranges (all compositions are by weight on an oxide basis), especially based on the specific optical state of each of the glasses of the present invention. Refractive index n _d is 1.60 to 1.61, Abbe number ν _d
But heavy crown glass of 58~60: SiO ₂ 35~3
_{6%; B 2 O 3 11~12.5} %; BaO 45.5
４７47.5%; ZnO 0.01-0.2%; TiO ₂
0.1~0.4%; ZrO ₂ 0.01~0.1%;
Al ₂ O ₃ 4.5~6%.

Heavy crown glass having a refractive index n _d of 1.60 to 1.61 and an Abbe number ν _d of 59 to 60: SiO ₂ 3
_{4.5~36%; B 2 O 3 10.5~13} %; BaO
45-47%; ZnO 0.01-3%; TiO _{2
0.01~0.4%; ZrO 2 0.1~0.3%;} A
_{l 2 O 3 5~6%; Na} 2 O 0.3~0.5%.

Heavy crown glass having a refractive index n _d of 1.61 to 1.62 and an Abbe number ν _d of 58 to 60: SiO ₂ 3
_{3.5~35.5%; B 2 O 3 11.5~13} %; B
aO 46.5-48.5%; ZnO 0.3-1%; T
_{iO 2 0.2~0.4%; ZrO 2 0.01~0} .
_{3%; Al 2 O 3 4~5.5} %.

Heavy crown glass having a refractive index n _d of 1.62 to 1.63 and an Abbe number ν _{d of} 56 to 58: SiO ₂ 3
_{2~33.5%; B 2 O 3 9~10.5} %; BaO
48.5~50%; ZnO 1.5~3%; TiO 2
_{0.1~0.3%; ZrO 2 0.01~0.15%;} A
_{l 2 O 3 4.5~6%; Na} 2 O 0~0.3%.

[0028]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples. Examples 1 to 16 Sixteen examples of the glass according to the invention from conventional raw materials were melted. Tables 2 and 3 show the composition (weight% based on oxide), refractive index n _d , Abbe number ν _d , and density ρ (g / cm) of each glass.
³ ), coefficient of thermal expansion α _20/300 (10 ⁻⁶ / K) and transition temperature T
_g (° C). The glass according to the present invention was produced as follows. Oxide raw materials (see the dissolution examples in Table 1) were weighed. The fining agent Sb ₂ O ₃ was added and mixed well. The glass batch was melted at about 1,380-1,540C and subsequently clarified and well homogenized. Casting temperature is 1,180 ~
1,360 ° C. Glasses with a relatively high proportion of SiO ₂ and ZrO ₂ require relatively high melting and casting temperatures, while glasses with a high proportion of B ₂ O ₃ , F ⁻ , P ₂ O ₅ have relatively low melting and casting. Requires temperature. Table 1
Shows two dissolution examples calculated per 100 kg. The properties of the glass obtained in this melting example are shown in Table 2 in Example N
o. No. 3 and Example No. 3 in Table 3. 13 corresponds.

[Table 1]

Tables 2 and 3 show the compositions (% by weight based on the oxides) of the glasses obtained in the examples and the main properties of the glasses.

[Table 2]

[0030]

[Table 3]

[0031]

As described above, the composition range of the glass according to the present invention provides another group of lead-free heavy crown and extra heavy crown optical glasses having the above-mentioned optical properties. This glass satisfies the requirement of sufficient chemical resistance. This is important for rework and glass applications such as grinding and polishing. Compared to conventional lead and arsenic containing glasses of the same optical state, the glasses according to the invention have an improved acid resistance. For example, ISO
No. 8424 in the acid resistance test. Twelve glasses (see Example 12 and Table 3) reached an acid resistance rating of 51.2, and the corresponding conventional lead and arsenic containing glass of the same specific optical state was rated 51.3. It just does. The number at the end of the grade indicator is to indicate a visible surface change. Class 2 indicates that oxygen corrosion according to the grade indicates only slight selective leaching (interference color), whereas in case 3 a thin white film is formed which sticks. No. in the spot resistance test. The glass of No. 5 (see Example 5 and Table 2) is assigned a spot resistance rating of 3.

The degree of spot resistance is determined by the following method. That is, a surface-polished test glass sample is pressed onto a test cell in which several drops of each test solution are placed in a polished spherical cavity having a maximum depth of 0.25 mm. Test solution I: standard acetate, pH = 4.6 Test solution II: sodium acetate buffer, pH = 5.6 Due to the action of the test solution, degradation of the glass surface results more or less rapidly in spots of buffer color. For grading the glass, the time required for the first brown-blue discoloration to occur at 25 ° C. is employed. This discoloration is characterized by a predefined chemical change of the surface layer of about 0.1 μm thickness, assuming that the glass is generally capable of forming a layer (see Table 4).

Table 4 shows the classification of the optical glasses according to the spot resistance rating FR 0-5 based on the time when brown-blue spots (layer thickness 0.1 μm) were formed at 25 ° C. by the test solutions I and II.
Shown in

[Table 4] The spot resistance rating FRO encompasses all glasses that show virtually no interference color when the test liquid I is operated for 100 hours. 1
Glasses that cause discoloration in less than 00 hours belong to grades FR1-5, while glasses with grade FR1 are the slowest grades FR
5 indicates the most rapid speckle formation.

The glass according to the present invention has excellent crystallization stability, which allows continuous production of the glass in a large melting equipment, for example, an optical tank kiln. For example, the glass of Example 5 has a temperature range of 850 to 1,020 ° C, and the glass of Example 11 does not show devitrification at a temperature range of 830 to 1,000 ° C. This is in each case 6,000-35.
This corresponds to a viscosity range of 0 dPas. The glass of Example 12 has a viscosity of 3,200 dPas at the upper limit temperature of devitrification, and the glass of Example 13 has a viscosity of 6,100 dPas. Thus, these values are clearly above the critical limit of 1,000 dPas for continuous production.

The glass according to the invention can be produced at an advantageous cost, since it does not contain or reduce the proportion of some expensive components. The fact that the glass does not contain PbO is not only important in terms of environmental protection in question, but is also advantageous in that it generally reduces the density of the glass. Also, the redevelopment of the batch composition required for that has a positive effect on the "glass length", i.e. the size of the temperature range in which the glass can be processed. Further, the glass of the present invention is advantageous in that it not only does not contain PbO, but also does not contain As ₂ O ₃ in a preferred embodiment.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Uwe, Kolberg, Germany, 55252 Mainz, Fresselweg 1 (72) Inventor Danuta, Gravoski, Germany, 65232 Taunusstein, Fau. Day. Kirchforst 16a (72) Inventor Magdalena, Winkler-Trudevig Germany, 55126 Mainz, Amm, Kirchborn 20 b. 26 (72) Inventor Alvin, Weizel Germany, 55120 Mainz, Vestring 283

Claims (15)

[Claims] 1. The following composition based on oxides: _{20 to} 37% by weight of SiO _2, 8 to 20% by weight of B ₂ O ₃ , 43 to 55% by weight of BaO, 0.01 to 10% by weight of ZnO, 0 to 7% of CaO wt%, MgO 0 to 7 wt%, however, CaO + MgO 0 to 7 wt%, however, BaO + ZnO + CaO + MgO <60 wt%, TiO ₂ 0.01 to 5 wt%, ZrO ₂ 0.01 to 7 wt%, Al ₂ O ₃ 0.1 to 10 wt%, Na ₂ O 0 to 8% by weight, K ₂ O 0 to 8 wt%, _{however, Na 2 O + K 2 O} 0~8 wt%, La ₂ O ₃ 0 to <3 wt% , F ^- 0 to 1% by weight, P ₂ O ₅ 0 to 3% by weight, optionally containing a conventional amount of a fining agent, characterized by a refractive index of 1.60 to 1.65. n _d and 50
A lead-free heavy crown or extra heavy crown optical glass having an Abbe number ν _{d of} 60. 2. The following composition based on oxides: _{20 to} 37% by weight of SiO _2, 11 to 20% by weight of B ₂ O ₃ , 43 to 55% by weight of BaO, 0.1 to 10% by weight of ZnO, 0 to 7% of CaO wt%, MgO 0 to 7 wt%, however, CaO + MgO 0 to 7 wt%, however, BaO + ZnO + CaO + MgO <60 wt%, TiO ₂ 0.01 to 5 wt%, ZrO ₂ 0.05 to 7 wt%, Al ₂ O ₃ 0.1 to 10 wt%, Na ₂ O 0 to 8% by weight, K ₂ O 0 to 8 wt%, _{however, Na 2 O + K 2 O} 0~8 wt%, La ₂ O ₃ 0.1 to <3 ^wt%, F - 0.05 to 1% by weight, P ₂ O ₅ 0 to 3 wt%, have, according to claim 1, characterized in that it contains conventional amounts of fining agent, if necessary Lead-free heavy crown or extra heavy crown optical glass. 3. The following composition based on oxide: 26 to 34% by weight of SiO _2, 12 to 15% by weight of B ₂ O ₃ , 43 to 52% by weight of BaO, 0.1 to 4% by weight of ZnO, 0 to 2 of CaO 2 wt%, MgO 0 to 2 wt%, provided that, BaO + ZnO + CaO + MgO <60 wt%, TiO ₂ 0.01 to 3 wt%, ZrO ₂ 0.1 to 4 wt%, Al ₂ O ₃ 0.5 to 7 wt%, Na ₂ O 0 to 2 wt%, K ₂ O 0 to 2 _{wt%, La 2 O 3 0.1~ <} 3 ^wt%, F - 0.05 to 1 wt%, P ₂ O ₅ 0~3 wt% The lead-free heavy crown or extra heavy crown optical glass according to claim 1 or 2, further comprising a fining agent in a conventional amount as required. 4. The following composition based on oxides: 26 to 33% by weight of SiO _2, 12 to 15% by weight of B ₂ O ₃ , 43 to 52% by weight of BaO, 0.1 to 4% by weight of ZnO, 0.1 to 4% by weight of TiO ₂ . 01-3 wt%, ZrO ₂ 0.1 to 4 wt%, Al ₂ O ₃ 0.5~7 _{wt%, La 2 O 3 0.1~ <} 3 ^wt%, F - 0.05 to 1 wt% , P ₂ O ₅ 0 to 3 wt%, have, according to any one of claims 1 to 3, characterized in that it contains conventional amounts of refining agents optionally unleaded heavy crown or especially Heavy crown optical glass. 5. The following composition based on oxides: 28 to 31% by weight of SiO _2, 13 to 14% by weight of B ₂ O ₃ , 47 to 50% by weight of BaO, ₂ to 3% by weight of ZnO, 0.1 to 0.1% of TiO ₂ 0.3 wt%, ZrO ₂ 0.1 to 1 wt%, Al ₂ O ₃ 4~5 wt%, La ₂ O ₃ 0.2~0.6 ^wt%, F - 0.05 to 0.1 weight %, P ₂ O ₅ 0 to 3 wt%, have, optionally conventional amounts of the refractive index n _d and 57 to the 1.61 to 1.64, characterized in that it contains a clarifying agent
Unleaded heavy crown or especially heavy crown optical glass according to any one of claims 1 to 4 having an Abbe number [nu _d 59. 6. The following composition based on the oxide: 32 to 34% by weight of SiO _2, 13 to 14% by weight of B ₂ O ₃ , 43 to 45% by weight of BaO, 3 to 5% by weight of ZnO, 0.01 to 0.01% of TiO ₂ 0.1 wt%, ZrO ₂ 0.05 to 0.3 wt%, Al ₂ O ₃ 3~5 wt%, La ₂ O ₃ 0.1~0.4 ^wt%, F - 0.8 to 1 weight %, P ₂ O ₅ 0 to 3 wt%, have, optionally conventional amounts of the refractive index n _d and 58 to the 1.60 to 1.62, characterized in that it contains a clarifying agent
The lead-free heavy crown optical glass according to claim 1, having an Abbe number ν _{d of} 60. 4. 7. The following composition based on the oxide: 31 to 37% by weight of SiO _2, 8 to 14% by weight of B ₂ O ₃ , 45 to 51% by weight of BaO, 0.01 to 4% by weight of ZnO, 0 to 7% of CaO wt%, MgO 0 to 7 wt%, however, CaO + MgO 0 to 7 wt%, however, BaO + ZnO + CaO + MgO <60 wt%, TiO ₂ 0.01 to 0.5 wt%, ZrO ₂ 0.01 to 0.4 wt% , Al ₂ O ₃ 3 to 7% by weight, Na ₂ O 0 to 1% by weight, K ₂ O 0 to 2% by weight, P ₂ O ₅ 0 to 3% by weight. A refractive index n _{d of} 1.60 to 1.63 and 55 to 55, which contains a fining agent.
60 unleaded heavy crown optical glass according to claim 1 having an Abbe number [nu _d of. 8. The following composition based on oxides: 32 to 36% by weight of SiO _2, 9 to 13% by weight of B ₂ O ₃ , 45 to 50% by weight of BaO, 0.01 to 3% by weight of ZnO, 0.02% by weight of TiO ₂ . 01 to 0.4 wt%, ZrO ₂ 0.01 to 0.3 wt%, Al ₂ O ₃ 4 to 6 wt%, Na ₂ O 0 to 0.5 wt%, has a customary optionally characterized in that it contains an amount of fining agent refractive index n _d and 55 of 1.60 to 1.63
60 unleaded heavy crown optical glass according to claim 1 or 7 having an Abbe number [nu _d of. 9. The following composition based on oxides: 35 to 36% by weight of SiO _2, 11 to 12.5% by weight of B ₂ O _3, 45.5 to 47.5% by weight of BaO, 0.01 to 0.1% of ZnO. 2 wt%, TiO ₂ 0.1 to 0.4 wt%, ZrO ₂ 0.01 to 0.1 wt%, Al ₂ O ₃ 4.5 to 6 wt%, it has a conventional amount as required And a refractive index n _d of 1.60 to 1.61 and 58 to
60 unleaded heavy crown optical glass according to claim 1, 7 or 8 having an Abbe number [nu _d of. 10. The following composition based on oxides: 34.5 to 36% by weight of SiO _2, 10.5 to 13% by weight of B ₂ O _3, 45 to 47% by weight of BaO, 0.01 to 3% by weight of ZnO, TiO ₂ 0.01-0.4 wt%, ZrO ₂ 0.1-0.3 wt%, Al ₂ O ₃ 5-6 wt%, Na ₂ O 0.3-0.5 wt% , of 1.60 to 1.61, characterized in that it contains conventional amounts of fining agent, if necessary refractive index n _d and 59 to
60 unleaded heavy crown optical glass according to claim 1, 7 or 8 having an Abbe number [nu _d of. 11. The following composition based on oxides: 33.5 to 35.5% by weight of SiO _2, 11.5 to 13% by weight of B ₂ O _3, 46.5 to 48.5% by weight of BaO, ZnO 0 .3～1 wt%, a TiO ₂ 0.2 to 0.4 wt%, ZrO ₂ 0.01 to 0.3 wt%, Al ₂ O ₃ 4 to 5.5 wt%, and optionally And a refractive index n _d of from 1.61 to 1.62 characterized by containing a conventional amount of fining agent.
60 unleaded heavy crown optical glass according to claim 1, 7 or 8 having an Abbe number [nu _d of. 12. The following composition based on oxides: 32 to 33.5% by weight of SiO _2, 9 to 10.5% by weight of B ₂ O _3, 48.5 to 50% by weight of BaO, 1.5 to 3% by weight of ZnO %, TiO ₂ 0.1 to 0.3% by weight, ZrO ₂ 0.01 to 0.15% by weight, Al ₂ O ₃ 4.5 to 6% by weight, Na ₂ O 0 to 0.3% by weight. a, of 1.62 to 1.63, characterized in that it contains conventional amounts of fining agent, if necessary refractive index n _d and 56 to
58 unleaded heavy crown optical glass according to claim 1, 7 or 8 having an Abbe number [nu _d of. 13. The lead-free heavy crown or extra heavy crown optical glass according to claim 1, which contains 0 to 0.3% by weight of Sb ₂ O ₃ . 14. The lead-free composition according to claim 13, comprising 0 to 1% by weight of Cl ⁻ , wherein the total amount of Sb ₂ O ₃ and Cl ⁻ is at least 0.05% by weight. Heavy crown or extra heavy crown optical glass. 15. The lead-free heavy crown or extra heavy crown optical glass according to claim 1, which contains no arsenic oxide except for inevitable impurities.