Polymer interlayers comprising epoxidized vegetable oil

Abstract

An interlayer comprised of a thermoplastic resin, varying amounts of an epoxidized vegetable oil, and, optionally, a conventional plasticizer. The use of a thermoplastic resin, an epoxidized vegetable (plant) oil, and, optionally, a conventional plasticizer creates synergy allowing the flow of the interlayer to be increased without sacrificing other characteristics typically associated with an increased flow (e.g., increased blocking and creep, exudation, surface roughness formation, decreased mechanical strength, and decreased manufacturing capability). In this regard, the epoxidized vegetable oil acts as a flow improvement agent, resulting in a high-flow interlayer. As a result, a thinner interlayer can be utilized in forming multiple layer panels because the resulting thinner interlayer has improved flow properties.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This disclosure is related to the field of polymer interlayers for multiple layer panels and multiple layer panels having at least one polymer interlayer sheet. Specifically, this disclosure is related to the field of polymer interlayers comprising epoxidized vegetable oil.[0003]2. Description of Related Art[0004]Generally, multiple layer glass panels refer to a laminate comprised of a polymer sheet or interlayer sandwiched between two panes of glass. The laminated multiple layer glass panels are commonly utilized in architectural window applications, in the windows of motor vehicles and airplanes, and in photovoltaic solar panels. The first two applications are commonly referred to as laminated safety glass. The main function of the interlayer in the laminated safety glass is to absorb energy resulting from impact or force applied to the glass, keep the layers of glass bonded even when the force is applied and the glas...

AI Technical Summary

Benefits of technology

The patent describes a new interlayer for use in multiple layer panels and other applications. The interlayer is made up of a mixture of poly(vinyl butyral) resin and a mixture of plasticizers. The plasticizers can include triethylene glycol di-(2-ethylhexanoate), triethylene glycol di-(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, diisononyl adipate, heptylnonyl adipate, and dibutyl sebacate. The interlayer can also contain epoxidized vegetable oil. The high-flow interlayer has improved properties, such as high flow and good adhesion to the resin. The patent also describes a multilayered interlayer with two layers of poly(vinyl butyral) resin and a third layer of poly(vinyl butyral) resin. The interlayer can be used in multiple layer panels and other applications.

Problems solved by technology

Generally, two (2) common problems are encountered in the art of manufacturing multiple layer glass panels: delamination and bubbling from inefficient de-gassing.

This typically occurs around the edges of the multiple layer glass and is usually the result of the breakdown of the bond between the glass and the interlayer by atmospheric moisture attack or panel sealant degradation, or excessive stress imposed on the glass.

Some degree of edge delamination is a common problem in multiple layer glass panels.

Furthermore, if the delamination extends too far into the panel, the structural integrity of the glass panel may become compromised.

However, these technologies are not always effective in removing all of the air trapped in the interstitial spaces between the substrates, especially when one or more of the substrates is wavy or warped.

For example, the processing of tempering glass creates some distortion and roller waves, and thus tempered glass is generally not as flat as ordinary annealed glass.

In such applications, the waviness of the substrates creates gaps between the substrates themselves and between the substrates and the interlayer, resulting in an increased tendency of delamination and bubble formation.

Both delamination and bubble formation are undesirable and problematic where the end-product multiple layer glass panel will be used in an application where optical quality or structural integrity is important.

It is not an uncommon defect in the art of multiple layer glass panels for dissolved gases to appear (e.g., for bubbles to form) in the panel over time, especially at elevated temperatures and under certain weather conditions and sunlight exposure.

The excessive air trapped in the laminated panels will significantly reduce the tolerance of the panels for the elevated temperatures and adverse weather conditions, i.e., bubbles could be formed at lower temperatures.

However, there are several problems with these interlayer compositions previously utilized in the art.

For example, with an increase in thickness comes an increase in both cost and price.

Additionally, increasing flow creates other problems of its own, including: blocking, plasticizer exudation, creep, surface roughness formation, decreased mechanical strength, and decreased manufacturing capability.

Blocking can be a problem during the manufacturing, storage and distribution of polymer interlayer sheets, where it is not uncommon for the polymer interlayer sheets (which in some processes are stored in rolls) to come into contact with each other.

When the flow of the interlayer is increased, generally the interlayer is softer and becomes more susceptible to blocking, and as a result, it can be difficult, if not impossible, to separate the polymer interlayer sheets.

If the plasticizer content is above its saturation point, exudation occurs and the plasticizer flows out of the interlayer, which will impose difficulties with the handling of the interlayer and cause contamination on the interlayer and the processing equipment.

Creep can be problematic because multiple layer glass panels tend to become deformed and elongated as a result of the creep of interlayer.

Thus, with previous attempts at increasing flow came a greater tendency for creep and the resultant deformation of the interlayer.

In some situations, this creep can result in structural defects and decreased mechanical strength of the interlayer and the resultant multiple layer glass panel.

If the surface roughness is too low, de-gassing will become impossible.

On the other hand, if the surface roughness is too high, the large surface irregularities in the interlayer will be difficult to remove during lamination, resulting in more gas being trapped in the multiple layer glass panel.

Either too low or too high surface roughness will result in poor de-gassing performance and cause more bubbling and delamination described above.

In general the increase of flow will result in the decrease of surface roughness, which will make de-gassing more difficult, causing more bubbling and delamination.

Again, such bubbling and delamination is undesirable and can result in structural defects and decreased mechanical strength of the interlayer and the resultant multiple layer glass panel.

Summarized, delamination and bubbling are common problems in the field of multiple layer glass panels which are particularly acute when using wavy or warped substrates.

The increased thickness and / or flow of the previously utilized interlayers, however, resulted in numerous other unfavorable sacrifices, including, but not limited to, increased manufacturing costs (i.e., the costs associated with an increased thickness in the interlayer), blocking, creep, exudation, surface roughness formation, decreased mechanical strength, and decreased manufacturing capability.

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