JPH0789021A - Light-stable laminate and method of forming same - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a light-stable and optically transparent laminate using an inexpensive styrenic polymer and a method for forming the same. [Structure] The laminate formed according to the present invention has a pendant hydroxyl functional group introduced into a styrenic polymer by copolymerization, and thus imparts high interfacial adhesive force without an additional adhesive layer. be able to. These pendant hydroxyl groups react with the active pendant ester groups carried by the other polymer layers in the laminate, preferably by heating the layers during the compression molding process or during the coextrusion process of the layers. , A strong covalent bond is formed at the interface.

Description

Detailed Description of the Invention

The present invention relates to a photostable polymer laminate and a method for making the same. More particularly, the present invention relates to polystyrene-formed polystyrene formed by interfacial bonding of a functionalized styrenic copolymer with a polymer having pendant ester groups such as polymethylmethacrylate.
It relates to a polymethylmethacrylate laminate.

General purpose polystyrene (GPPS) has optical and mechanical properties similar to polymethylmethacrylate (PMMA) when protected from UV radiation.
Moreover, GPPS can be easily thermoformed into various shapes. However, unlike polymethylmethacrylate, GPPS is hypersensitive to light and undergoes oxidative degradation by light on its surface. Therefore, when exposed to UV light for a long time, the polymer becomes yellow and brittle. Due to this UV sensitivity, GPPS is recommended for outdoor applications, such as window glass for residential and commercial windows, or for other indoor or outdoor applications that may be exposed to UV light. Its use is quite limited.

At present, light-stable outdoor window glass applications include:
Acrylic resins such as PMMA are widely used because of their optical transparency and photostability. Polycarbonate is used for applications that require high impact resistance. However, the cost of acrylic resin is GPP
It is about twice as much as S, and polycarbonate is also expensive.

Polystyrene is a light stable material (eg P
Various studies have been made to prevent polystyrene from being affected by ultraviolet rays by being laminated on MMA). For example, "" Advances in light stability PS sheet ", flops
Lastic World , October 1982, p. 5 ”. However, as is well known, an acrylic resin such as PMMA has poor compatibility with general-purpose crystalline polystyrene and is therefore difficult to bond. Without an adhesive layer, the laminate of GPPS and PMMA would easily delaminate by the application of a very small external force. Although an adhesive layer made of an adhesive based on urethane resin or epoxy resin may be interposed, such an adhesive is
It has undesirable properties such as opacity and cloudiness.

To form a laminate with an acrylic resin,
There are references using styrene copolymers. For example, US Pat. No. 4,350, by Hall,
No. 742 describes an acrylic resin film made of poly (styrene-co-acrylic acid) [poly (styrene-
co-acrylic acid)] (SAA). However, SAA copolymers are more susceptible to rapid UV degradation than polystyrene itself. Therefore, the SAA copolymer is not suitable for outdoor use even when laminated on an acrylic resin.

[0006] Therefore, in the industry, there is a demand for a material which is light stable and transparent as required, and which is cheaper than acrylic resin or polycarbonate. Further, in the industry, there is a demand for a material that is light stable, inexpensive, and has a small amount of heat transfer for windows for general houses and commercial and industrial facilities. Further, there is a need in the art for a method of integrally bonding incompatible styrene-based polymers and acrylic polymers without interposing an adhesive.

The present invention is carried out by laminating an inexpensive styrene-based polymer on a light-stable and optionally transparent laminated structure, and a polymer having a pendant ester group (for example, an acrylic polymer). This need is met by providing a method of making a laminate structure. The resulting laminate has strong interfacial adhesion without the use of additional adhesive due to the use of pendent hydroxyl functional groups introduced into the styrenic polymer by copolymerization. These pendant hydroxyl groups react with the active ester groups on the other polymer layers in the laminate to form strong interfacial covalent bonds. Furthermore, the resulting laminate is thermoformable.

In accordance with one aspect of the present invention, there is provided a method of forming a photostable laminate by bonding layers of incompatible polymers without the use of adhesives. Copolymerizing 1 to 10% by weight of a reactive comonomer containing a precursor for a moiety or hydroxyl moiety with a styrenic monomer to form a copolymer layer having pendant hydroxyl functional groups. Examples of suitable comonomers include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, and mixtures thereof,
It is not limited to these. By "precursor to a hydroxyl moiety" is meant a pendant moiety capable of undergoing a pre-reaction to carry a hydroxyl group.

The copolymer layer and the polymer layer are then heated, preferably in a compression molding step or a coextrusion step of the copolymer layer and the polymer layer having the pendant ester group, whereby the copolymer layer and the pendant ester group are heated. Bonded to the polymer layer. Suitable polymers having pendant ester groups include polymers of acrylic acid and polymers of methacrylic acid (eg polymethylmethacrylate). If necessary, the laminate formed by the method of the present invention can be biaxially stretched to increase the mechanical strength.

In a preferred embodiment, the copolymerization is
Performed in the presence of a catalyst such as benzoyl peroxide. Further, the copolymerization is preferably carried out at a temperature of 80 to 125 ° C. for a time sufficient for the polymerization to occur (usually 24 to 48 hours).

The interfacial bonding step can be carried out by applying heat, which causes the pendent hydroxy functional groups on the styrenic comonomer to react with the corresponding active ester groups on the preferred acrylic polymer layer. The two are combined. Preferred methods for bonding include compression molding the polymer and copolymer layers together under heat and pressure, or coextruding the polymer and copolymer layers from a common die.

In another embodiment of the present invention, 1-10% by weight of a reactive comonomer containing a hydroxyl functional alkyl ester of acrylic acid or methacrylic acid is copolymerized with a styrenic monomer to form a pendant form. There is provided a method of forming a photostable laminate by bonding layers of incompatible polymers without the use of adhesives, the method comprising forming a copolymer layer having hydroxyl functional groups of. The copolymer layer is then bonded to the polymer layer by heating the copolymer layer and a polymer layer containing pendant ester groups (preferably a polymethylmethacrylate layer).

The invention further provides a first copolymer layer comprising 1 to 10% by weight of a copolymer of a styrenic monomer and 1 to 10% by weight of a reactive comonomer containing a hydroxyl functional group-containing alkyl ester of acrylic acid or methacrylic acid. A first copolymer layer forming a layer having pendant hydroxyl functional groups to which another layer of a polymer having pendant ester groups (eg, polymethylmethacrylate) is attached. It relates to a light-stable laminate structure. In a preferred embodiment, the first layer is sandwiched and bonded between layers of polymethylmethacrylate to produce a three-layer stack. In this method, a photosensitive styrenic comonomer is present between the layers of the light stable acrylic resin and is protected from UV light. When light stability is an important point, the thickness of the polymethylmethacrylate layer should be 5 mil (0.1 mm) to 20 mil (0.5 mm) to provide sufficient protection from UV light. preferable.

In another embodiment of the present invention, a five-layer, light-stable laminate structure is provided, the laminate structure comprising a polystyrene core layer having two major surfaces. On each of the two major surfaces of the core layer,
A copolymer layer comprising a copolymer of 1 to 10% by weight of a reactive comonomer containing a hydroxyl functional group-containing alkyl ester of acrylic acid or methacrylic acid and a styrenic monomer, the copolymer layer having pendant hydroxyl functional groups. Are combined. In addition, each of the copolymer layers is associated with another layer of polymer containing pendant ester groups (eg, polymethylmethacrylate). The thickness of polymethylmethacrylate layer is 5
From mil (0.1 mm) to 20 mil (0.5 mm),
It is preferable to provide sufficient protection from ultraviolet rays.

The photostable laminate structure according to the present invention comprises:
It is an inexpensive alternative to the prior art materials and does not require the use of additional adhesives that can adversely affect the optical properties and processability of the polymer, making it suitable for insulating glazing in residential and commercial buildings. (EN) A suitable structure having a small heat transfer amount is provided. Since no additional adhesive layer is needed, during the coextrusion process for producing the laminate,
It is no longer necessary to match the viscosity of the adhesive layer with that of the polymer. Furthermore, it is not necessary to match the viscosity of the adhesive layer with the viscosity of the polymer during thermoforming for producing the laminate. Eliminating the need for an adhesive layer means that it is easier to manufacture.

Further, the laminate of the present invention has excellent optical properties, so that it can be used as a multilayer laminate for optical interference coatings and reflective polymer bodies. The method of the present invention can be used to provide multilayer thin films, coextruded microlayer films, or controllable interfacial adhesion that allows for improved processing flexibility and tailored end-use properties. Sheet can be manufactured.

Accordingly, an object of the present invention is to provide a material which is cheaper than acrylic resin or polycarbonate, has low heat transfer characteristics, is light-stable, and is transparent as required for window glass for general houses and commercial and industrial facilities. To provide. Another object of the present invention is to provide a laminate containing a styrene-based polymer and an acrylic-based polymer and having a strong interfacial adhesion without requiring an additional adhesive layer. These and other objects and advantages of the invention will be apparent from the following detailed description, the accompanying drawings and the claims.

According to the present invention, a light-stable and optionally transparent laminate containing an incompatible styrene polymer and an acrylic polymer is provided. At this time, the layers constituting the laminate are provided. Are chemically bonded at their interfaces. These bonds are formed by reacting a functionalized styrenic copolymer having pendant hydroxyl functional groups with the co-reactive ester groups present on the surface of the acrylic polymer layer under heat.

As used herein, "styrene-based monomer" refers to styrene, alkenyl aromatic monomers containing alkylstyrene, halogenated styrene, and styrene and a small amount of co-reactive monomers (eg, acrylonitrile, Alkyl alcohol, and a mixture with vinyl acetate, etc.). Similarly, "styrenic polymer" and "styrenic copolymer" mean polymers and copolymers derived from the above monomers.

Reactive hydroxyl functional groups can be incorporated into the styrenic polymers of this invention by copolymerizing the styrenic monomer with a sufficient amount of a reactive comonomer. These hydroxyl functional groups form covalent bonds with the co-reactive ester groups present in the other polymer layers, which chemically bonds the two polymer layers. It is preferred to use from 1 to 10% by weight of a reactive comonomer containing a hydroxyl moiety or a precursor to a hydroxyl moiety. Such comonomers are preferably selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, and mixtures thereof.

The reaction that occurs at the interface is a condensation reaction that occurs at pendant hydroxyl functional sites in polystyrene and at co-reactive ester sites in, for example, polymethylmethacrylate, as shown by Formula I below, thereby covalent A bond is formed.

[0022]

The weight percent of reactive comonomer can be varied to control the degree of interfacial adhesion obtained. That is, many pendant hydroxyl functional reactive sites present on the styrenic polymer react to form a strong bond, but the use of a very small amount of co-reactive monomer reduces the number of reactive sites. Therefore, the degree of adhesion between layers is correspondingly reduced. One of ordinary skill in the art can adjust the mechanical properties of the laminate (eg, impact strength, tensile strength, ductility, etc.) by varying the degree of adhesion obtained.

The laminate produced by the method of the present invention, when subjected to biaxial stretching, has improved mechanical properties over acrylic resins such as polymethylmethacrylate alone. Unlike polystyrene, polymethylmethacrylate is difficult to stretch. However, the laminate of the present invention contains a styrenic component layer which can be stretched (preferably biaxially stretched) to improve toughness, tensile strength and impact strength.

The copolymerization of the styrenic monomer and the hydroxyl functional group-containing acrylate is preferably carried out in the presence of a catalyst such as benzoyl peroxide. Further, the copolymerization is preferably carried out in two steps of mixing liquid monomers and heating at about 80 ° C. for 24 to 48 hours, and then heating at 125 ° C. for another 24 hours.

The laminate structure of the present invention may be a two-layer laminate, a three-layer laminate, or a laminate containing more layers. The laminate of the present invention is used for outdoor applications exposed to ultraviolet rays (for example, for external insulating window glass).
In the case of being used for the above, a laminated body composed of three or four layers in which polymethylmethacrylate forms an outer protective layer of the laminated body is preferable. For example, by bonding a first layer of functionalized polystyrene sandwiched between layers of polymethylmethacrylate, a preferred three-layer laminate is obtained. When the laminate is prepared by this method, the photosensitive styrene copolymer is protected by being sandwiched between the layers of the light stable acrylic resin. The thickness of the polymethylmethacrylate layer is 5 mil (0.1 mm) to 20 mil (0.5 m
m) is preferred. The functionalized polystyrene layer can have any useful thickness desired.

In another embodiment, a five layer photostable laminate structure can be made that includes a polystyrene core layer having two major surfaces. Attached to each major surface of the core layer is a copolymer layer containing functionalized polystyrene with pendant hydroxyl groups. In addition, another polymethylmethacrylate layer is bonded to each of the copolymer layers. The thickness of the polymethylmethacrylate layer is 5 mil (0.1 mm) ~
It is preferably 20 mils (0.5 mm). The polystyrene layer and the functionalized polystyrene layer can have any useful thickness desired. The laminate of the present invention can be formed by a method in which heat is applied to each layer to cause a reaction at the interface. One preferred method is to use heat and pressure to compression mold the layers, thereby causing a bond. Another preferred method is to co-extrude the functionalized polystyrene copolymer and polymethylmethacrylate in-line. A sufficient amount of heat is generated from the polymer stream exiting the extrusion die and due to the contact of the layers at the interface, which causes the binding reaction to covalently bond the two polymers. The coextrusion operation can be repeated to add more layers, or a multi-layer coextrusion die can be used.

Further, the method of the present invention is described in US Pat.
Using the multi-layer coextrusion equipment described in US Pat. Nos. 773,882 and 3,884,606, microlayer coextrusion.
Ion). Such a device provides a method of producing a coextruded multilayer thermoplastic material, each layer having a substantially uniform thickness. US Pat. No. 3,75
A series of layering means described in 9,647, the disclosure of which is incorporated herein by reference, can be used.

Feed block of coextrusion device
A dblock) receives a stream of various thermoplastic polymer materials from a device such as a thermoplastic extruder. The resinous stream is sent to the machine operating section in the feedblock. This section serves to rearrange the initial flow into a multilayer flow with the number of layers required for the final article. If desired, this multi-layer stream can subsequently be passed through a series of multi-layering means to further increase the number of layers in the final article.

The multi-layer stream is then fed into an extrusion die which is constructed so that the laminar stream is maintained. Such an extrusion device is described in US Pat. No. 3,557,265. The article thus obtained is extruded to form a multilayer body in which each layer is approximately parallel to the major surface of the adjacent layer.

In order that the present invention may be better understood, the following examples will be given to explain the present invention, but these examples are for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention. Not something.

Example 1 Styrene and hydroxyethyl methacrylate (HEM
Polystyrene with functionalized pendant hydroxyl groups was synthesized by copolymerizing with A). Styrene (95 pph), HEMA (5 pph),
And benzoyl peroxide (0.2 pph) were mixed and polymerized in two steps (80 ° C. for 48 hours and 125 ° C. for 24 hours). These liquid monomers undergo a polymerization reaction to give a glassy transparent polymer [poly (styrene-co-HEM
A)] [poly (styrene-co-HEM
A)] was generated.

Other polymers used in this example were polymethylmethacrylate (PMMA) [ROHM.
Plexiglas from And Haas
as) purchased under the trade name of V811] and general-purpose polystyrene [STYRO from Dow Chemical Co.
N) Purchased under the trade name of 685D]. The polymers were blended in a Plasti-Corder Brabender machine at 190 ° C and 60 rpm. The change in viscosity (determined from the torque data recorded on the chart paper) was observed to investigate the polymer reaction that was taking place.

FIG. 1 shows PMM blended at 190 ° C.
FIG. 2 shows torque data for the A melt; FIG.
FIG. 3 shows torque data for poly (styrene-co-HEMA); FIG. 3 shows torque data for blending a 60/40 (w / w) mixture of PMMA and general purpose polystyrene (Stylon 685D). In both cases, the torque did not increase during the blending operation. From this, it is understood that PMMA and PS-HEMA do not cause a crosslinking reaction, and PMMA does not react with general-purpose polystyrene under the above conditions.

PMMA and poly (styrene-co-HEM)
When the 60/40 (w / w) mixture with A) was mixed and melted at 190 ° C., the torque started to increase significantly from around 6 minutes of mixing time (see FIG. 4). This indicates that PMMA in the melt reacts with poly (styrene-co-HEMA) as shown in the following reaction formula to form a covalently crosslinked polymer.

[0036]

Example 2 Poly (styrene-co-HEMA) was prepared by copolymerizing styrene and HEMA according to the procedure described in Example 1.
(Crystalline transparent styrene copolymer) was synthesized. Poly (styrene-co-HEMA) and PMMA compression molded sheet (4 inch x 6 inch x 0.015 inch)
(10 cm x 15 cm x 0.38 mm), temperature 190 ° C (Chase size: 4 inches x 6 inches x
0.030 inch) (10cm × 15cm × 0.76m
m); pressed in a compression molding machine at a drum pressure of 40,000 psi (274 MPa) with a cycle time of 5 minutes of preheating, 5 minutes of curing, and 5 minutes of cooling. The two-layer laminate thus obtained was tested for adhesion by applying a safety razor blade to the PMMA / poly (styrene-co-HEMA) interface. The obtained result is HE
It is shown in Table 1 below as a function of MA content.

[0038]

PMMA and poly (styrene-co-HEM)
The high interfacial adhesion strength with A) is considered to be due to the occurrence of the interfacial chemical reaction as described in Example 1.

A copolymer of styrene and 5 wt% hydroxyethyl acrylate (HEA) was also synthesized. When hot pressed with PMMA under the above conditions, a two-layer laminate without separation was obtained.

Example 3 PMMA / Poly (styrene-co-HEMA) / PMMA
Was prepared by coextrusion. The extrusion line comprises a first and a second extruder, each extruder having a diameter of 3 /
It has a 4 inch (19 mm) screw, a length to diameter ratio of 15, two temperature control zones, and a compression ratio of 2.5. 20 lbs / hr with 2 inch (5 cm) die width and 0.080 inch (2 mm) die gap
A feedblock coextrusion die with a capacity of (9 kg / hr) was used.

PMMA (Plexiglas V811) was supplied to the first extruder and operated at 45 rpm to reach 5500.
The discharge pressure was psi (37.7 MPa). The two temperature control zones were operated at 430 ° F (220 ° C). The poly (styrene-co-HEMA) (5%) prepared in Example 1 was supplied to the second extruder and operated at 25 rpm to a discharge pressure of 2000 psi (13.7 MPa). The first temperature control zone is 300 ° F (150 ° F)
Operating in the second temperature control zone at 450 ° F (2 ° C).
30 ° C.). The feedblock coextrusion die has a temperature of 450 ° F (230 ° C) and 6 lb / h
The extrusion rate was maintained at r (2.7 kg / hour).

PMMA / Poly (styrene-co-HEM)
A) / PMMA (25% / 50% / volume% respectively)
25%) of the three layer laminate was found to have excellent interfacial adhesion at the polymer interface.

Example 4 PMMA / Poly (styrene-co-HEMA) (5%) /
Polystyrene / poly (styrene-co-HEMA) (5
%) / PMMA 5-layer laminate was made by coextrusion. The extrusion line includes first, second, and third extruders with diameters of 1.5 inches (38 mm) and 0.7, respectively.
5 inches (19 mm) and 1.25 inches (32 m
m) screw. 5 inches (12.7 mm)
A 5-layer feedblock coextrusion die having a die width of 0.125 inch and a die gap of 0.125 inch (3.2 mm) was used.

PMMA was supplied to the first extruder, and 11
Operated at rpm. The temperature in the supply zone should be 400 ° F (2
04 ℃), the remaining 4 temperature control zones 45
Operated at 0 ° F (230 ° C). The second extruder was the poly (styrene-co-HEMA) prepared in Example 1.
(5%) was supplied and operated at 20 rpm. The two temperature control zones were maintained at 400 ° F (204 ° C). Third
The extruder was supplied with polystyrene and operated at 100 rpm. 380 ° F (193 ° C) for three temperature control zones
C)). The temperature of the 5-layer feedblock coextrusion die was maintained at 450 ° F (230 ° C). After co-extruding, the resulting five layer laminate was 230 ° F. (110
(C) was passed between the polishing rolls.

PMMA / Poly (styrene-co-HEM)
A) / Polystyrene / Poly (styrene-co-HEMA)
/ PMMA (13.5% / 2.5% in volume% respectively
/68%/2.5%/13.5%) five-layer laminate was found to have excellent interfacial adhesion at the polymer interface.

Example 5 The light stability of PMMA and other styrenic polymers used in the present invention was investigated. 2 inch x 2 inch (5 cm x 5 cm) samples with various thicknesses were placed on an aluminum foil, and a high-intensity UV source (G
It was placed 12 inches (30 cm) away from the E-275W UV lamp. The samples were exposed to UV light for various times. The Yellowness Index of the samples was determined using the ASTM-D1925 test method.

Table 2 summarizes the measurement results of the yellowness index. The larger the value of the yellowness index, the more intense the yellowing. Yellowing of the sample is a result of the oxidative degradation of the polymer caused by light. PM
MA has excellent photostability. The yellowness index of PMMA only changed slightly for 264 hours of UV exposure. The photostability of functionalized polystyrene containing pendant hydroxyl groups (copolymer of styrene and 5 wt% HEMA; PS-HEMA) and GPPS is relatively similar. However, poly (styrene-co-
3 wt% acrylic acid) deteriorated rapidly when exposed to an ultraviolet lamp. After 168 hours of exposure, the polymer was dark brown in color and too brittle to be tested for mechanical properties.

3 consisting of PMMA / GPPS / PMMA
The photostability of the three-layer laminate composed of the layer laminate and PMMA / PS-HEMA / PMMA is GPPS or PS-HEMA.
Better than light stability. A 5 mil (0.13 mm) thick PMMA layer coated on the surface of GPPS suppresses photo-induced oxidative degradation (see Sample 6). However, PMMA / GPPS / PM
MA three-layer stacks are easy to separate and therefore do not appear to have practical utility. PMMA / PS-HEM
The three-layer laminate of A / PMMA has improved light stability and excellent interfacial adhesion.

[0050]

Example 6 In this example, the surface protection effect of PMMA on polystyrene will be further described. Two 0.013 inch (0.33 mm) thick PMMA layers and a thickness of 0.013
PMMA / GPPS / PMMA (2 inches x 2) composed of one GPPS inner layer of inch (0.33 mm)
Inch x 0.039 inch) (5cm x 5cm x 1m
The laminate sheet of m) was exposed to a GE-275W UV lamp for 400 hours as described above. Sample of GPPS (2 inches x 2 inches x 0.013) (5 cm x 5 cm x 0.
33 mm) was also exposed to a UV lamp under the same conditions.
After exposure, the yellowness index of the sample was measured. Then P
The individual layers in the MMA / GPPS / PMMA 3-layer sheet were separated and the respective Yellowness Index was measured. The results are shown in Table 3.

[0052]

From this example, it can be seen that when GPPS is protected by PMMA, GPPS hardly yellows even after long-term UV exposure. Without the PMMA protective layer, GPPS caused significant discoloration.

Example 7 Tensile properties of a 0.044 inch (1.1 mm) thick PMMA / poly (styrene-co-HEMA) / PMMA three layer sample were measured using a 0.044 inch (1.1 mm) thick G layer.
Compared to the tensile properties of PPS samples. These two samples were first exposed to UV light as described above and then evaluated for tensile properties. The results obtained are shown in Table 4.

[0055]

The tensile strength of GPPS not protected with PMMA showed a decrease after 72 hours of UV exposure. In contrast, the PMMA / poly (styrene-co-HEMA) / PMMA three-layer stack did not show a decrease in tensile strength after being exposed to UV light for 168 hours.

Example 8 Composed of two 11 mil (0.28 mm) thick PMMA skin layers and one 33 mil (0.84 mm) thick poly (styrene-co-5 wt% HEMA) inner layer. A 55 mil (1.4 mm) thick coextruded PMMA / poly (styrene-co-HEMA) / PMMA laminate was exposed to UV as previously described. The impact strength (measured with a Dynatup impact tester) of the sample before exposure was 3.24 ± 0.48 inch-pound / 55.
It was a mil (2.62 ± 0.39 J / cm). The impact strength of this sample remained virtually unchanged after exposure to UV light for 72 hours (3.96 ± 0.060 inch-
Lbs / 55 mils (3.20 ± 0.05 J / cm).

While particular exemplary embodiments have been described to illustrate the invention, those skilled in the art will appreciate that
It goes without saying that various modifications can be made to the method and apparatus disclosed herein without departing from the scope of the invention as defined in the claims.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship of torque versus mixing time for a melt of polymethylmethacrylate blended at 190 ° C.

FIG. 2 Poly (styrene-co-) blended at 190 ° C.
5 is a graph showing the relationship between torque and mixing time for a melt of 5 wt% HEMA).

FIG. 3 is a graph showing the relationship of torque versus mixing time for a melt of a 60/40 weight ratio mixture of PMMA and polystyrene blended at 190 ° C.

FIG. 4 is a graph showing torque versus mixing time for a melt of a 60/40 weight ratio mixture of PMMA and poly (styrene-co-5 wt% HEMA) blended at 190 ° C.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/00 C 8413-4F 27/08 8413-4F // B29K 25:00 33:04 B29L 9 : 00 (72) Inventor Mark A. Berger, Helen Street, Midland 48640, Michigan, USA 129

Claims (19)

[Claims] 1. A copolymer having 1-10% by weight of a reactive comonomer containing a hydroxyl moiety or a precursor for the hydroxyl moiety and a styrenic monomer to have pendant hydroxyl functional groups. Forming a layer; and (b) bonding the polymer layer and the copolymer layer by heating the polymer layer containing a pendant ester group and the copolymer layer; A method of forming a photostable laminate by combining layers of incompatible polymers without use. 2. The reactive comonomer is hydroxyethyl acrylate, hydroxyethyl methacrylate,
The method of claim 1 selected from the group consisting of hydroxybutyl methacrylate, and mixtures thereof. 3. The polymer containing pendant ester groups is polymethylmethacrylate.
The forming method described. 4. The forming method according to claim 1, comprising the step of stretching the laminate by biaxially stretching the laminate. 5. The method according to claim 1, wherein the copolymerization is carried out in the presence of a catalyst. 6. The method according to claim 5, wherein the copolymerization is performed at a temperature of 80 to 125 ° C. 7. The method of claim 1, wherein the bonding step comprises compression molding the polymer layer and the copolymer layer together under heat and pressure. 8. The method of claim 1, wherein the bonding step comprises coextruding the polymer layer and the copolymer layer from a common die. 9. The method of claim 1, wherein the comonomer comprises a hydroxyl functional group-containing alkyl ester of acrylic acid or methacrylic acid to form a copolymer layer having pendant hydroxyl functional groups. 10. The forming method according to claim 9, comprising the step of stretching the laminate by biaxially stretching the laminate. 11. The formation method according to claim 9, wherein the copolymerization is carried out in the presence of a catalyst. 12. The method according to claim 11, wherein the copolymerization is performed at a temperature of 80 to 125 ° C. 13. The method of claim 9, wherein the bonding step comprises compression molding the polymer layer and the copolymer layer together under heat and pressure. 14. The method of claim 9, wherein the bonding step comprises coextruding the polymer layer and the copolymer layer from a common die. 15. The first layer comprises 1 to 10% by weight of a hydroxyl moiety or a precursor to the hydroxyl moiety.
Of a polymer having a pendant hydroxyl functional group, and a copolymer of a styrenic monomer and a reactive comonomer of A photostable laminate structure having multiple layers characterized in that the layers are bonded. 16. The photostable laminate structure of claim 15, wherein the reactive comonomer comprises a hydroxyl functional group-containing alkyl ester of acrylic acid or methacrylic acid. 17. The photostable laminate structure of claim 15, wherein the polymer having pendant ester groups is polymethylmethacrylate. 18. The first layer is bonded while sandwiched between layers of polymethylmethacrylate.
7. The photostable laminate structure according to 7. 19. The photostable laminate structure of claim 18, wherein the polymethylmethacrylate layer has a thickness of 5 mils (0.1 mm) to 20 mils (0.5 mm).