JPH02199151A - Improved methyl methacrylate composition - Google Patents

Abstract

PURPOSE: To obtain a molded item having resistances to weather and ultraviolet rays by adding an alcohol or a high-boiling-point hydroxy compd. to the polymn. mixture before or after the polymn. for forming an alkyl methacrylate polymer.

CONSTITUTION: An ultraviolet-resistant alkyl methacrylate polymer is obtd. by mixing about 96 wt.% base mixture comprising an alkyl methacrylate and an alkyl acrylate with about 4 wt.% ethyl acrylate, mixing the resultant mixture with 0.5-2 wt.% alcohol component selected from among an alcohol (e.g. methyl or ethyl alcohol), a high-boiling-point hydroxy compd. (e.g. ethylene glycol, glycerin, butyl lactate, or diethylene glycol), or their mixtures, adding a chain transfer agent (e.g. n-dodecyl mercaptan) so that the mol.wt. of the finally resultant polymer is 100,000-500,000, and conducting the polymn. These additives may be added after the polymn. or when at least 50% of the residual monomer is removed.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to acrylic polymer compositions that can be used to make plastic articles with increased weather and UV resistance.

[Conventional technology and its problems] Methyl methacrylate polymers have only 10% resistance to ultraviolet rays.
Deteriorates if exposed for 0 hours. Ultraviolet light also tends to cause yellowing in methyl methacrylate polymers, which concomitantly reduces the UV transmission ability of methyl methacrylate. The reduction in the UV transmission ability of methyl methacrylate polymers is always a concern in the sunbed industry since sunburn reduces the efficiency of its operation.

Prior art has attempted to counteract the degrading effects of ultraviolet light on methyl methacrylate by incorporating light stabilizers into these materials.

For example, in U.S. Pat. No. 4,550.136,
Prior to association, sterically hindered amines (sterically hindered amines)
hin-dered amines; HAL
S) For example, 2,2,6,6-titramethyl-piperidine is added to the methyl methacrylate monomer. (
1-IALS> results in a methyl methacrylate polymer with improved resistance to UV radiation;
Addition of TALs is expensive.

Conventional techniques also show that the UV resistance of acrylic systems can be improved by the addition of propyl alcohol! I came to see it. Ninis Belihenkor (8.

On the decomposition mechanism of polymers under 4g UV and gamma irradiation: influence of low molecular weight additives on vibrational mutual relaxation (On t
he) 1echanism of polymer D
construction under uvand Ga
mma Irradiation: The In
fluence of LowMolecular W
eight Additives Re1ated
o Vibra-tional Cross-Rela
xation) ''' (Sixth
Symposium on Radiation Chemistry (
Sixth Symposium on Ra-dia
tion Chemistry) 1986, 53
Samples of the polymer were prepared by bulk radical polymerization of heptamer compositions of methyl methacrylate admixed with about 5-20% propyl alcohol, as discussed on pages 5-538]. The resulting polymer showed improved resistance to UV light for short exposures of about 100 hours. However, exceeding 5% by weight,
It is expected that large amounts of propyl alcohol will degrade the physical and mechanical properties of these polymers.

There is therefore a need to provide methyl methacrylate compositions that are inexpensively manufactured and exhibit improved resistance to long-term exposure to ultraviolet light without the need for the addition of large amounts of additives.

SUMMARY OF THE INVENTION The present invention relates to methacrylate polymers that exhibit improved resistance to long-term exposure to ultraviolet radiation. The seven-mer mixture used to make methacrylate polymers is
Alkyl methacrylates such as methyl methacrylate,
and a base mix of alkyl acrylate monomers having 1 to 4 carbon atoms in the alkyl group (Base
Hix). Alcohols, high boiling hydroxy compounds, and mixtures thereof may be added to the base mix of monomers prior to polymerization. Alternatively, alcohols, high boiling hydroxy compounds, and mixtures thereof may be added to the polymerized base mix. High boiling hydroxy compounds may be used in place of or in combination with alcohol additives. Chain transfer agents may also be added to the base mix of monomers to control the molecular weight of the resulting polymer.

The compositions of the present invention can be formed into sheet products and articles with complex shapes that exhibit surprisingly improved resistance to ultraviolet light. The polymer compositions may also be made up into molding materials used, for example, in the manufacture of melt calendered sheets and articles with complex shapes.

The invention is illustrated in detail by the following description and non-limiting examples.

In accordance with one aspect of the invention, aliphatic alcohols, high boiling hydroxy compounds, or combinations thereof, as well as additional additives such as chain transfer agents, can be mixed with the base mix of alkyl methacrylate and alkyl acrylate monomers ( After that, 4g pre-addition (p
Preferably,
The alkyl methacrylate is methyl methacrylate (M
MA), and the alkyl acrylate is preferably ethyl acrylate (EA). Other alkyl acrylates such as butyl acrylate and methyl acrylate can also be used with (MMA). (MM
A) can constitute about 90 to about 100% by weight of the base mix. Accordingly, up to about 10% by weight of alkyl acrylate may be included in the base mix. Preferably, the base mix of monomers is about 9
Contains 6% by weight methyl methacrylate and about 4% ethyl acrylate.

In the pre-addition, approximately 0.5-2. O11i% aliphatic alcohol is added to the base mix. Preferably, an aliphatic primary or secondary alcohol having 1 to 10 carbon atoms is added to the base mix. Most preferably methyl and ethyl alcohol are added to the base mix. In other embodiments, a mixture of fatty alcohols may be added to the base mix composition.

In still other embodiments, high boiling hydroxy compounds such as ethylene glycol and glycerin can be used in place of or combined with the aliphatic alcohol. Additives outside the range of 0.5 to 2% by weight may be added to the base mix provided that they do not reduce the physical properties of the resulting alkyl methacrylate polymer product. Furthermore, in order to control the molecular weight of the resulting polymeric material, a chain transfer agent, e.g.
may be added to the base mix. Preferably, a sufficient amount of chain transfer agent is added to the base mix composition to produce a polymeric material having a molecular weight of 100,000 to 500,000.

After the additives are added to the base mix of monomers, the resulting composition can be formed, eg, into a polymerized sheet product, eg, by standard cell casting techniques. Other methods, such as emulsion polymerization and suspension polymerization, can also be used to produce polymerized products. It can be used up to 43m.

EXAMPLES Pre-addition Numerical Operations: Examples 1-12 In accordance with the pre-addition embodiment of the present invention, a base mix of monomers of (MMA) and an alkyl acrylate such as ethyl acrylate (EA) is prepared. Alcohol additives having 1 to 10 carbon atoms or high-boiling hydroxy compounds such as butyl lactate, ethylene glycol or glycerin are added to the base mix. Cellular cast sheet products can be formed by stirring a mixture of monomers and additives and pouring into a sealed mold. The mixture is heated to about 45-120° C. to substantially completely polymerize the base mix and form a polymerized methyl methacrylate polymer (PMMA) cell cast sheet product.

The effect of alcohol additives and high-boiling hydroxy compounds on the UV resistance of (PMMA) products made according to pre-added standards (PMMA) according to ASTM standards (3-5)
3-84, by long-term exposure to ultraviolet light over the wavelength range of 290-400 nm. Approximately 0.
A 170-inch thick sample was prepared using a Phi-11ips Corp.
290-32 from the FS40 fluorescent lamp
0 nm (, “LIVB”). Another sample of these (PMMA) products was manufactured by Q-Panel corpora with an emission peak at 314 nm and a 1% emission peak cutoff at 284 nm.
315~40 from UVA-351 lamp of tton>
It was exposed to 0 nm ("UVA") irradiation.

(PMMA) The irradiation resistance of the product is 300nllll and 34
The percent total ultraviolet light transmittance of the (PMMA) product at a wavelength of 0 nm was evaluated by comparing before and after (UVA) and (UVB) irradiation using a spectrophotometer.

In addition to evaluating the UV resistance of these compositions based on the percent total transmittance of 300 and 340 nm radiation, alcohol additives and high boiling points regarding the degree of yellowing of (PMMA) compositions made by predoping. The effect of hydroxy compounds was also determined. The degree of yellowing is determined by (UVA) or (U
VB) Determined by comparing the yellow color in the (PMMA) product after roughening to either radiation and the yellow color in the (PMMA) product before exposure to (UVA) or (UVB) radiation. The result (yellow index (yellow index)
OW-ness 1ndeX: Y I ) was evaluated according to ASTM test method [ ) 1925. The effect of pre-addition of aliphatic alcohol additives and high-boiling hydroxy compounds on the UV resistance of pre-added cell cast (PMMA) products is shown in Table 1.

Examples 1 to 12 in Table 1 are (MMA') and (EA)
Figure 2 illustrates the effect of pre-addition of alcohol and high boiling hydroxy additives on the UV resistance of a (PMMA) product made from a base mix of (PMMA).

As shown in Table 1, (PMMA) products using alcohol and high boiling hydroxy additives have (tJV△)
Even after 6000 hours of irradiation, 30
Maintains extremely high rate of transparency at 0 nm.

As shown in Example 3, (EA) containing (PMMA)
has a transmittance of 84.3% for 300 nm radiation. Percent total transmittance t'- at 300 nm of the composition of Example 3 after exposure to (UVA) irradiation for 6000 hours
Ha, 76.9% teal. (UVA) (7) Irradiation 1600
A comparison of the percent transmittance for irradiation at 300 nm after 0 hours of exposure to the original transmittance of the material at 300 nm of 84.3% shows that the composition of Example 3 It shows retention of approximately 91.7% of the transmittance of the unexposed (PMMA) composition. however,
As shown in Example 1, without any additives (PMMA), the unexposed (PMM
A) Only about 40% of the product's transmittance at 300 nm is maintained.

Pre-dosing can also be used in the production of (PMMA) resin molding materials used in the production of injection molded articles and melt calendered sheets, e.g.
(PMMA) sheet material can be ground into particles and extruded to make pellets of molded resin material. Alternatively, the base mix of monomers can be made into a molded resin material by methods such as emulsion polymerization and suspension polymerization.

As an alternative to pre-addition, alcohol and high boiling hydroxy compound additives can be incorporated into the (PMMA) by directly treating the (PMMA) with the additive. This method [post-addition
n)'' is particularly suitable for supplying materials for molding and extrusion into complex articles, such as covers for high-intensity discharge lamps.

Various methods can be used to achieve post-addition of alcohol additive to (PMMA).

For example, the additive can be added directly to the liquid polymer. Additives can also be incorporated into the polymer by treating the surface of the polymer with the additive at room temperature and then melting the treated polymer. Post-additions can be carried out at temperatures ranging from ambient temperature to about 300°C. If the additive is applied in liquid form (PMMA), high boiling point additives are preferred to minimize volatilization of the additive.

The high boiling point additives that can be used are preferably 4
Includes aliphatic alcohols having ~16 carbon atoms. Particularly preferred high-boiling additives for addition to liquid (PMMA) are ethylene glycol, diethyl glycol,
Includes butyl lactate and glycerin.

In Examples 13-17 shown in Table 2, methyl methacrylate (MMA) was about 95% by weight, ethyl acrylate (EA) was about 4% by weight, 100,000-500, 0
A mixture of n-dodecylmer-butane (n-DDM>about 0.20% by weight) as a chain transfer agent giving a molecular weight of
(PMMA) was made by heating with about 0.02 double butyl peroxide.

The mixture was heated at a temperature and time sufficient to cause at least 50% conversion to polymer.

Additives are preferably applied after substantially all residual monomer has been removed from the polymer.

Residual monomer may therefore be removed prior to "post-addition" of the additive. The additive is applied to the liquid polymer just before coagulation. Preferably, the additive is The additive is applied while at a temperature within the range of about 200 to about 250°C. Alternatively, the additive is applied at ambient temperature (P
Additives can be post-added to (PMMA) by providing tI@ to M M A ). The treated (PMMA) is then heated above its glass transition temperature, preferably with stirring, to incorporate the additive into the polymer.

The effect of alcohol additives and high-boiling hydroxy compounds on the UV resistance of (PMMA) products made by post-addition has determined that the (PMMA) products can be evaluated according to ASTM Standard G-
53-84, by long-term exposure to ultraviolet light over the wavelength range of 290 to 4001 m. Samples approximately 0.170 inch thick were sampled using a 290~290°C fluorescent lamp from a Philips FS40 fluorescent lamp with an emission peak at 314nm and a 1% emission peak cutoff at 284nm.
It was roughly irradiated with 320nll ("LJ V B"). Another sample of these (PMMA) products was
Q-Panel's U't,/A-3 with an emission peak at 0 m and a 1% emission peak cutoff at 284 nm
From 51 lamps, 315-400 n1ll ("L
JVA”) irradiation.

Made by post-addition (PMMA)! I! The radiation resistance of the product is 300 nm and 3
The total transmittance percent of ultraviolet light with a wavelength of 40 nm is expressed as (
PMMA) product (D) by comparing before and after (UVA) and (UVB) irradiation using a spectrophotometer.
evaluated.

As shown in Table 2, the polymeric materials made by post-dosing also retain a surprisingly high transmittance after exposure to UV light. As shown in Example 14 of Table 2, (
Post-addition of 1% ethylene glycol to PMMA)
Provides a material with an original transmittance of 60.6% to 00nllll (UVA).

This material has a wavelength of (7) 100 to 300 nm (UVA)
After 0 hours of exposure, a transmission of 53.2% was retained for 300 nm (tJVA). The composition of Example 14 therefore retains a surprisingly high 87.78% of its original transmission to UVA radiation. On the other hand, Example 13, which does not use any additives, has 300 n
It retains only about 73.9% of its original transmittance at m.

Although the invention has been described and illustrated in great detail, various modifications, alternative embodiments, alterations and improvements can readily be made without departing from the nature and scope of the invention.

Claims (1)

[Claims] 1. A method for producing an alkyl methacrylate polymer product, comprising: preparing a mixture containing an alkyl methacrylate and an alkyl acrylate monomer; polymerizing the aforementioned mixture to produce an alkyl methacrylate polymer; the aforementioned alkyl methacrylate; Treating the polymer with an additive selected from the group consisting of alcohols, high boiling hydroxy compounds, and mixtures thereof and incorporating said additive into said alkyl methacrylate polymer material to provide improved resistance to ultraviolet light. A method of manufacturing an alkyl methacrylate polymer product exhibiting improved resistance to ultraviolet radiation, the method comprising obtaining an alkyl methacrylate polymer product. 2. The method of claim 1, wherein said alcohol additive is added to said alkyl methacrylate polymer material after substantially all of said mixture has been polymerized into said alkyl methacrylate polymer material. 3. The method of claim 1, wherein said alcohol additive is added to said alkyl methacrylate polymer material after at least 50% by weight of said mixture has been polymerized into said alkyl methacrylate polymer material. 4. The method of claim 1, wherein said treatment is carried out after removing at least 50% by weight of residual alkyl methacrylate and alkyl acrylate monomers from said alkyl methacrylate polymeric material. 5. The method according to claim 1, wherein said treatment is carried out when said mixture is a liquid. 6. The method of claim 5, wherein said mixture is at a temperature in the range of 200-250<0>C. 7. Said treatment is carried out by applying said additive to a coagulated alkyl methacrylate polymer to form a treated polymer and heating said polymer to incorporate said additive into the polymer. The method described in Section 1. 8. The method of claim 1, wherein the alkyl methacrylate is selected from the group consisting of methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the alkyl acrylate is selected from the group consisting of ethyl acrylate and butyl acrylate. 9. The method of claim 1, wherein said additive is a high boiling hydroxy compound. 10. The method of claim 1, wherein said additive is selected from the group consisting of ethylene glycol, glycerin, butyl lactate, and diethylene glycol. 11. The method according to claim 1, wherein 0.5 to 2% by weight of the additive is mixed into the alkyl methacrylate polymer. 12. The alkyl methacrylate polymer described above is 10
The method of claim 1 having a molecular weight within the range of 0,000 to 500,000.