A design of low shrinkage acrylate andthe mechanism of the hardening
K. Matsuoka*, N. Yoshioka*, and Y. Saruwatari*
Osaka Organic Chemical Industry LTD., Katayama-Cho, Kashiwara City, Osaka, Japan
Abstract- As for the merits of the acrylic monomer, fast cure rate, high transparency, and high hardness. On the otherhand, a demerit is the large shrinkage. Fortunately, we have succeeded in development the acrylate monomer MEGAm ofsuper low shrinkage. A possible mechanism is C – O bond cleavage and polymerization occur simultaneously by UV light.

I. INTRODUCTION
Ultraviolet light curable materials have been applied todisplay and optical film materials. There are many
advantages, including the fast cure rate, energy saving. At
the same time, there are unresolved difficulties. One ofthe problems is the shrinkage of the hardening. The
polymerization reaction as many molecules to a molecule,the cure shrinkage occurs in the gaps with a covalentbond distance from the conversion of van der Waals
distance (show Figure.1). As a way to avoid them, there
is a method using polymerizable oligomer. In order todesign more sophisticated materials are being sought toresolve the new approach.

Figure.3

III. RESULTS AND DISCUSSIONS
A. Behavier of the cleavage with UV irradiation.
R with a portion of the polyethylene glycol backbone"MEGAm" in Figure.2 compared with the sample A wassynthesized (show Figure.4) .
HNOO

Rn

< MEGAm >O

HN

Figure.1

OOn R< Sample A >OFigure.4
II. CONCEPTAs mentioned earlier, the mechanism of curingcontraction gaps in the distance that corresponds to vander Waals distance and covalent bonding. So we planneda monomer in Figure 2 is cleaved a part of the structure
as well as polymerization (show Figure. 3).

Figure. 2

Photoinitiator is added to each monomer,
decomposition behavior was observed in side chain withultraviolet irradiation by high performance liquid
chromatography(show scheme 1). As a result, methylenegroup was located between amide and ether groups(MEGAm) was found to absorb ultraviolet light andcleavage (Figure.5).
On the other hand, comparative example of theethylene group between the amide and ether groups(Sample A) showed no degradation (Figure.5).

HN

H 2COOnCH3REFERENCES

O

MEGAm

[1] K. Matsuoka, N. Yoshioka, and Y. Saruwatari, “Novel(meth) acrylic monomers and its manufacturing method”
JP P2009-155264A

irradiation

*nHN

*

[2] K. Matsuoka, N. Yoshioka, and Y. Saruwatari, “Novel(meth) acrylic monomers and its manufacturing method”
JP P2009- 263285 A
OH+HOOnCH 3O

Product A

Product B

Scheme 1Figure.5
B. Mesurement of cure shrinkage.
Results of the measurement, the cure shrinkage ofconventional monomer Sample A was 4.1%. Meanwhile,the newly developed MEGAm was 1.9%.
From these results, the cleavage site was introduced
acrylic monomer, cure shrinkage was much lower thanconventional monomer .

IV. CONCLUSIONS
To summarize, We have developed MEGAm show avery low cure shrinkage. A measure of the cure shrinkage
was found to be nearly zero. The shrinkage is low due tothe bond cleavage is the occurrence of van der Waals
distance.
Here we have developed MEGAm and that applied toholographic memory and found that the media made theerror rate is very low. In this presentation, and applicationof this material are discussed together, as incorporated
into the polymer structure is decomposed parts.

ACKNOWLEDGMENT
Special thanks to this development with Ms. Yoshioka
and Mr. Saruwatari. This study was done under thesupport of Osaka Organic Chemical Industry LTD.