Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1998-11-02
2001-01-30
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C264S176100, C264S211240, C264S219000, C528S271000
Reexamination Certificate
active
06180749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a glass clear heavy gauge sheet with copolyester which has excellent transparency and all properties with cheap production cost.
Polyethyleneterephthalate (hereinafter called “PET”) resin having been utilized in PET bottle, garment fiber, film and other vast fields due to its excellence of properties, processing, and economical aspects. It has been radically increased to use the PET resin as packing material based on its excellent mechanical properties, chemical resistance and recyclability. Sheet is one prevalently used among other fields, especially thin sheet(thinner than 1 mm) for vacuum forming. The polyester sheet thicker than 1 mm, however, is not easy for producing due to its crystallization and melt viscosity.
2. Description of Prior Art
In order to produce thick sheet(hereinafter called “thick sheet”) with polymeric material, the polymeric material needs to have properties of low crystallization speed and low crystallization degree with proper high melting viscosity in order to maintain forming stability in melting condition. A new trial for the purpose of satisfying these properties, was to produce a modified polyester by copolymerization.
There are two methods in producing the modified polyester as follow:
First of all, substitute the some part of terephthalate moiety used as acid component during PET polymerization, such as Dimethylterephthalate (hereinafter called “DMT”) or Terephthalic Acid (hereinafter called “TPA”) with Diacid or Diacidester. As for Diacid or Diacidester, Isophthalic Acid (hereinafter called “IPA”) or Dimethylisophthalate (hereinafter called “DMI”) are applied mainly. This method, in other words, is producing polyester copolymer by polymerizing [i] DMT or TPA, [ii] DMI or EPA and [iii] Ethyleneglycol (hereinafter called “EG”).
As expressed in following formula (I) and (II), TPA and IPA are same in their structure only except the position of functioning radical attached to Benzene chain.
[Formula (I) means TPA and formula (II) means IPA]
Since the reactivity of EPA in reaction circle during PET polymerization is fairly good, it reacts very well to some extent mol %. Since the copolyester, polymerized by some mol % of IPA or DMI, has the structure of formula (IV), it is different from homo PET which has the structure of formula (III).
According to the structural differences, the copolyester of formula (IV) has the effects of decreasing crystallization speed and crystallization degree since the interference to regularity of molecular chain during crystallization.
However, in proportion to the increase of EPA or DMI content, some properties of resin shall be suddenly deteriorated. In case, minimizing the IPA or DMI content for the purpose of preventing the deterioration of properties, it would not be possible to have the effects of sufficiently low crystallization rate. Because of this problem, the copolyester of formula (IV) constituted of around 3 mol % of EPA or DMI, is used only for producing thick bottle or thin sheet.
The second method is to substitute the some part of Ethyleneglycol used as one of the essential monomer applied during PET production with 1,4-Cyclohexandimethanol (hereinafter called “CHDM”). In other words, after preparing polyester copolymer by polymerizing [i] DMT or TPA, [ii] EG and [iii] CHDM, produce transparent and thick copolyester sheet by utilizing this polyester copolymer.
Since the length of CHDM molecule, having the structure of formula (V), is longer than that of EG, it disturbs the regularity of the molecule chain, and then decrease the crystallization rate and the crystallinity.
Furthermore, as the molecular chain of CHDM, like EPA, is not clamped, the reactivity and properties of polymer would not be deteriorated, and has high melt viscosity required for producing thick sheet even though the CHDM content increases
In order to obtain the properties, which enable to form the transparent and thick sheet, such as low crystallization rate, low crystallinity and high melt viscosity, it is necessary to use CHDM up to of 30 mol %. As a result, the producing cost comes to be very expensive and this is the limit in practical use.
Although, it is indispensable to have high molecular weight in order to obtain enough mechanical properties, if CHDM is polymerized in large quantity, there is no way except to raise molecular weight in the melt polymerization due to its amorphous phase by CHDM. Therefore, in order to obtain the high molecular weight, fairly good effort is needed to use with specially designed polymerization plant. Eastman Chemical Co. produces polyester copolymer by the second method, and sells them as common name “PETG” and also as trademark “SPECTAR”.
SUMMARY OF THE INVENTION
The present invention relates to a glass clear heavy gauge sheet with copolyester, having excellent transparency and all properties with cheap production cost, suitable for transparent soundproof wall and window glass substitute of the buildings.
More particularly, the present invention relates to a glass clear heavy gauge sheet with copolyester, having over than 83% of lights transmittance and lower than 5% of Haze, prepared by copolymer wherein polymerized [A] the acid component comprising (i) terephthalate moiety as major component and (ii) essentially including 2,6-naphthalenedicarboxylate moiety, and (iii) selectively including isophthalate moiety with [B] the glycol component of (i) ethyleneglycol (EG) itself or (ii) the mixture of ethyleneglycol (EG) and 1,4-cyclohexandimethanol (CHDM).
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is characterized by essentially applying 2,6-naphthalenedicarboxylate moiety as a part of acid component during polymerization, and at the same time selectively using isophthalate moiety in order to control specific thermodynamic requirements for forming transparent and thick sheet.
The present invention also characterized by selectively applying 1,4-cyclohexandimethanol (CHDM) as a part of glycol component.
In the present invention, dimethylterephthalate (DMT) or terephthalic acid (TPA) is mainly used as terephthalate moiety. Also, dimethyl-2, 6-Naphthalenedicarboxylate (hereinafter called “NDC”) or 2,6-naphthalene dicarboxylic acid (hereinafter called “NDA”) is mainly used as dimethyl-2, 6-naphthalenedicarboxylate moiety. As for isophthalate moiety, isophthal acid (IPA) or dimethylisophthalate (DMI) is used mainly.
For the purpose of producing transparent and thick sheet with polymer such as copolyester, following fundamental properties are required:
Firstly, thermal stability that molecular chain is not easily decomposed in melting condition is required since the material is processed in melting condition.
Secondly, high melt viscosity for maintaining the form as thick sheet in melting condition is required. However, if the melt viscosity is too high, it will be difficult to process. Therefore, the melting viscosity shall be high enough within the possible extent of processing.
Thirdly, sufficiently low crystallization is required. The thicker thickness sheet gets, the harder sheet cools. Therefore, in order to prevent the crystallizing which deteriorates the transparency of sheet, low crystallization rate is favorable and it is better if the material itself has low crystallinity.
In case, certain material partly meets the requirements among above, it is difficult to produce thick sheet. So, material needs to meet all possible properties.
The present invention will be illustrated more particularly hereunder.
After preparing the copolyester resin by melt polymerization [A] the acid component comprising (i) terephthalate moiety TPA or DMT is used as major component, (ii) essentially contains 2,6-naphthalenedicarboxylate moiety NDC or NDA, and (iii) selectively contains isophthalate moiety IPA or DMI with [B] the glycol component of (i) EG itself or (ii) the mixture of EG and CHDM, then pr
Kim Kyeong Ah
Kim Young Bum
Kim Young Seok
Shin Yong Cheol
Son Boung Kun
Birch & Stewart Kolasch & Birch, LLP
Boykin Terressa M.
Kolon Industries Inc.
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