JPS5996114A - Multilayer-structure polymer composition - Google Patents

Abstract

PURPOSE:A multilayer-structure polymer composition which, when incorporated in an acrylic resin, can improve its impact resistance, etc., prepared by consecutively laminating a layer of methyl methacrylate polymer, a layer of alkyl acrylate copolymer, and a layer of methyl methacrylate copolymer. CONSTITUTION:The titled composition of a particle size of 800-1,500Angstrom is prepared by consecutively laminating (A) 5-20pts.wt. polymer layer comprising 90- 100wt% methyl methacrylate and 10-0wt% copolymerizable monofunctional unsaturated monomer, (B) 55-80pts.wt. copolymer layer comprising 65-99.9wt% alkyl acrylate, 30-0wt% copolymerizable monofunctional unsaturated monomer, 0.5-0wt% polyfunctional grafting agent and 5-0.1wt% polyfunctional crosslinking agent of the formula (wherein m is 4-20 and R is H or CH3) formed in the presence of A, and (C) 15-40pts.wt. polymer layer comprising 80-99wt% methyl methacrylate and 20-1wt% copolymerizable monofunctional unsaturated monomer, formed in the presence of B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modifier for thermoplastic acrylic resin. Improved and stress mill 1
Regarding modifiers with less.

Acrylic resin is widely used both indoors and outdoors because of its excellent transparency, weather resistance, moldability, and beautiful appearance. However, unfortunately, this acrylic/I/resin does not necessarily have sufficient impact strength.
Furthermore, when exposed to certain solvents, crazes and cracks tend to occur, especially when internal stress or external stress is applied, and improvements in this respect have been desired.

By the way, to improve the impact resistance of acrylic resin, a method is generally used to blend rubber into a hard resin layer. For example, a three-layer or more multilayer structure of a polymer containing an elastic body and a hard thermoplastic is used. A method of improving impact resistance without impairing transparency by blending resin polymers has been proposed (Japanese Patent Publication No. 55-27576). In addition, the hard layer
A resin composition with excellent impact resistance and stress whitening resistance is also known, which has a structure having one hard layer and a middle layer having a concentration gradient that changes at a constant rate of y between these layers. (Japanese Unexamined Patent Publication No. 129449/1983, If!
3-58554). Furthermore, an impact resistance modifier with excellent stress whitening resistance is also known, which has a four-layer structure of soft layer - hard layer - soft layer - hard layer (Japanese Patent Laid-Open No. 55-949
17).

On the other hand, regarding the improvement of solvent resistance, for example, a method of incorporating acrylic threads or methacrylic oligomers (Japanese Patent Laid-Open No. 1983-1989-1)
131241), a method of copolymerizing certain acrylic and methacrylic yarn monomers (Japanese Patent Laid-Open No. 53-7792)
(Japanese Patent Application Laid-Open No. 54-99190), etc. have been proposed.

However, by these methods, it has not been possible to improve the sato impact resistance, solvent resistance, and stress whitening resistance while maintaining the original transparency, weather resistance, and moldability of acrylic resins.

The present inventors aimed to develop a resin that does not impair the transparency, weather resistance, and moldability of acrylic resin, improves the impact resistance and solvent resistance methods, and also has less flaking and whitening. As a result of extensive research, we have completed the present invention.

That is, the present invention provides a polymer comprising 90 to 100 N k % of methyl methacrylate obtained by emulsion polymerization, and 0 to 10 30 by weight of a monomer capable of copolymerizing therewith. 11 So [A], an acrylic acid alkyl ester (provided that the alkyl group has 2 to 8 carbon atoms) 65 to 99.
9 Jt amount %, 0 monofunctional unsaturated monomers copolymerizable with this
~30% by weight, polyfunctional grafting agent θ ~0.5% by weight, 0.1% polyfunctional crosslinking agent having the following structure (however, m is 4 to 2o
, , R is -H9 or HaCI■,) Copolymer second layer CB, 1, CB) is polymerized in the presence of methyl methacrylate 80
It has a multilayer structure consisting of a polymer third layer [C] consisting of ~99 M weight % and a monofunctional unsaturated monomer copolymerizable with the polymer third layer [C], and the third layer [C] further comprises n It is divided into stages (where n is 2 to 4), and the molecular weight gradually decreases from the inside to the outside, and the third layer first stage monomer weight is at least the third layer total monomer N amount. 21 or more, and each layer consists of a first layer of 5 to 20 parts by weight, a second layer of 55 to 80 parts by weight, a third layer of 15 to 40 parts by weight (total 100 parts by weight), and a particle size of 800 to 1 sooX. The present invention relates to a multilayer structure polymer composition characterized by the following: When blended with an acrylic resin by a known method, the composition can reduce the transparency, weather resistance, and moldability of the acrylic resin. Impact resistance and solvent resistance can be improved without any damage.

The present inventors have previously proposed a composition for a modifier that improves the impact resistance and solvent resistance of acrylic resin (% Application No. 84307/1983), but the present invention further improves the impact strength. This was the result of repeated research in order to do the same. The present invention will be explained in detail below.

The poly(+n) subaggregate composition of the present invention can be obtained by the emulsification method. In this case, it is necessary that no new particles be generated during polymerization of the second and third layers, and for this purpose, a so-called seed polymerization method is used. That is, the next layer is polymerized without adding any new emulsifier. Whether new particles are generated or not can be easily determined using an electron microscope.

Examples of emulsifiers used include emulsifiers commonly used in emulsion polymerization of acrylic esters and methacrylic esters, such as salts of long chain fatty acids, salts of sulfonic acids, dialkyl sulfosuccinates, polyoxythelene alkylphenyl ethers, etc. be.

The polymerization initiators used include water-soluble and oil-soluble radical initiators, and redox-type initiators are particularly preferred, such as cumene hydrobar oxide reducing agents, diisopropylbenzene hydrocarbon oxide reducing agents, etc. There is.

The polymer of the first layer contains methyl methacrylate as a main component, and desirably has a glass transition temperature (hereinafter abbreviated as Tg) of 50° C. or higher. If necessary, up to 10% by weight of monofunctional unsaturated monomers may be copolymerized, but it is necessary that no polyfunctional unsaturated monomers be used. When using polyfunctional unsaturated monomers, the desired high impact strength cannot be obtained.

The monofunctional unsaturated monomers used include alkyl acrylates, alkyl methacrylates, unsaturated aromatic monomers such as styrene, and unsaturated nitrile monomers such as acrylonitrile.

The polymer of the second layer is mainly composed of an acrylic acid alkyl ester that is polymerized in the presence of [A], and when polymerized in the absence of [A], the Tg is 0°C or less. desirable.

Examples of the acrylic acid alkyl ester that can be used include ethyl acrylate, propyl acrylate, butyl acrylate, allyl acrylate, and 2-ethylhexyl acrylate, and particularly preferred is acrylic acid v/I/butyl acrylate. , 2-ethylhexyl acrylate.

Copolymerizable monofunctional monomers include acrylic acid alkyl esters, methacrylic acid alkyl esters,
Examples include unsaturated aromatic monomers and unsaturated nitrile thread monomers.

When blended with an acrylic resin, especially when transparency is desired, a copolymerizable monomer is added so that the refractive index of the second layer polymer is substantially equal to the refractive index of the acrylic resin. You need to choose your body. Preferred monomers include styrene, phenyl methacrylate, naphthyl methacrylate, and the like.

It is a monomer having a plurality of unsaturated groups having a reactivity different from that of a polyfunctional grafting agent, and allyl acrylate, allyl methacrylate, allyl heptamalate, etc. are used. When the amount of polyfunctional grafting agent is more than 0.5%, the strength decreases by 1°.

As the polyfunctional crosslinking agent, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate represented by (R is H or CH3) are used. The average value of one synthetic leather hl of this ethylene glycol unit is 4 to 20, preferably 9 to 14. If the degree of polymerization is too small, the whitening effect will be reduced, and if it is too thick, the appearance of the molded product will be poor. If it is less than 0.1% by weight, the appearance and stress whitening resistance will deteriorate, and if it is more than 5% by weight, the strength will decrease.3. The third layer is methyl methacrylate, which is polymerized in the presence of CB). When polymerized in the absence of [B], it is desirable that its Tg is 50°C or higher.

This third layer is further divided into n stages (n is 2 to 4) (each called 1st stage + - 11th nR), and the molecular weight gradually decreases from the 1st stage to the nth stage. A major feature is that it is decreasing.

The molecular weight of the first stage is 300.000-5.000.000
, preferably in the range of 500,000 to 2,000,000. The molecular weight of this part is 300.0
If it is less than 00, good stress whitening resistance cannot be obtained, and in general, special reaction conditions (e.g. low temperature reaction, thorough removal of impurities, etc.) are required to achieve a value of 5,000,000 or more. It's /f.

On the other hand, the molecular weight of the outer shell of the 11th crosspiece (,6J is 60,00
0~200,000, preferably 80,000\15
It is desirable to set it in the range of 0.000. If the molecular weight of this portion is less than 60,000, solvent resistance and strength will be reduced, and if it is greater than 200,000, fluidity will be reduced. The molecular weight of each stage can be easily adjusted by changing the amount of chain transfer agent.

Furthermore, the amount of the monomer in the first stage must be equal to or greater than the total amount of monomer in the third layer (parts are the total amount of monomers in the first to nth stages). It is. If the amount of the first stage monomer is less than n, the desired stress whitening resistance cannot be obtained.

The amount of polymer in each layer is 1st layer 5-20 parts by weight 2nd layer 55-80 3rd layer 15-40 (100 parts by weight in total) It is necessary that

If each layer deviates from this amount, the strength, stress whitening resistance, and flowability will change. properties are destroyed, and the desired physical properties cannot be obtained.

The particle size of this multilayer structure polymer is required to be 800 to 1500^. If the particle size is smaller than 800X, the strength will decrease, and if it is thicker than 1500λ, the solvent resistance and stress whitening resistance will be poor.

The multiperiphery structure polymer of the present invention is used by blending it with pellets and beads for ordinary acrylic resin molding materials in any proportion. The acrylic resin to be blended may be one obtained by any known one-polymerization method, such as bulk polymerization, suspension polymerization, emulsion polymerization, or solution polymerization.
This can be done by any commonly used method.

In addition, during polymerization and blending, additives that are normally used within the range that does not impair the original characteristics, such as ultraviolet absorbers,
Plasticizers, lubricants, dyes and pigments, etc. can be added.

This will be explained in more detail below with reference to Examples. Measurements in the Examples were carried out by the following method.

1) Solvent Resistance An injection molded specimen was fixed at one end with the fulcrum as the boundary, a load was applied to the other end, and a solvent was dripped onto the fulcrum to examine the time it took for the specimen to break.

2) DuPont impact strength: Using a DuPont falling weight impact tester (manufactured by Toyo Seiki Co., Ltd.), test by dividing the product of the load and falling distance by the thickness at which half of the 3-thick specimens crack. Ta.

3) Izotsu impact strength It was investigated using the method of ASTM-D 256.

4) Particle size Particle size was examined using an electron microscope.

5) Liquidity Liquidity is Melt 70-Index (abbreviated as Onishita MI)
, i.e. 230 according to the method of ASTM-D 1238.
Measured at ℃ and load N3.8.

(2) Stress whitening resistance The specimen was pulled and the state of whitening at a predetermined elongation rate was visually examined.

7) Molecular weight The molecular weight of each third layer σ is the molecular weight of the polymer obtained by polymerizing each monomer mixture alone in chloroform solvent.
Calculated from the intrinsic viscosity measured at 25°C.

Example 1 In a 10-e beaker equipped with a stirrer and a condenser, 5.7 ml of distilled water, 20 t of sodium dioctyl sulfosuccinate as an emulsifier, and 1.2 z of chlorine rongalite as a reducing agent are added and uniformly dissolved. As the first layer, methyl methacrylate (hereinafter abbreviated as MMA 9220f, Ac IJ A=butyl acid (hereinafter abbreviated as BA) 3.OI, di-1-noglobilbenzene hydroperoxide (hereinafter abbreviated as 1) BP) 0. A homogeneous solution of 2SF- was added and polymerized at 80°C. The reaction was completed in about 15 minutes.

Then, as a second layer, B A 1270 i, styrene (
(hereinafter abbreviated as St) 320 i, polyethylene glycol dimethacrylate with an average degree of polymerization of ethylene glycol units of 9 (trade name NK Ester-9G, manufactured by Shin Nakamura Chemical) 5
0t, allyl methacrylate (hereinafter abbreviated as ALMA) 5P
, a homogeneous solution of PBpt6y was added one drop per hour. The reaction was completed 40 minutes after the completion of the subsurface treatment.

Next, use MMA3407 as the third step)
．． Bi2, (171P It I' 0.3 f,
n-octyl mercaptan (hereinafter abbreviated as I-OM)
A homogeneous solution of 0.1 f was added.

The reaction was completed in about 15 minutes. Next, the second stage of the third layer,
The amount of OM is 10? A homogeneous solution having the same composition as the first layer was added to the third layer except for the following. The reaction was completed in about 20 minutes. When the homogeneous solutions of each stage were combined individually, the molecular weight of the obtained polymer was 1.220,000.117,0, respectively.
It was 00. The temperature was then increased to 95°C and held at that temperature for 1 hour. The particle size of the obtained polymer was 1050^. This latex was poured into a 0.5% aluminum chloride aqueous solution to coagulate the polymer, which was then washed and dried to obtain a floc-like white polymer.

Example 2 A C resin was prepared in the same manner as in Example 1 except that the composition shown in Table 1 below was used as the third layer.

Table 1 Examples 3 and 4, Comparative Examples 1 to 3 Bo-1 ethylene glycol diacrylate shown in Table 2 was used as the polyfunctional crosslinking agent in the second layer. Resin?: It was submerged.

Table 2 Example 5, Comparative Example 4 A resin was prepared in the same manner as in Example 1, except that the composition shown in Table 3 below was used as the third JvJ.

Comparative Example 5 The composition of the first layer of Example 1 was ALMAo, 8? The resin was prepared in the same manner as in Example 1, except that the V strength was increased. Made in Ishi, Delvera)
8ON) were mixed in a ratio of 1=1, passed through an extruder to form pellets, and then injection molded (R) to form various specimens and measure each characteristic.

” down the street,

Claims (1)

[Claims] 1. Methyl methacrylate 9 obtained by emulsion polymerization
from 0 to 100% by weight, and from 0 to 10% by weight of a monofunctional unsaturated monomer copolymerizable with this monomer. acrylic acid alkyl ester (however, the number of carbon atoms in the alkyl group is 2 to 8) 65 to 9c+, polymerized in the presence of [A] [A]
,9. 0 to 30% by weight of a monofunctional unsaturated monomer copolymerizable therewith, O to 0.5% by weight of a polyfunctional crafting agent,
Polymerized in the presence of a copolymer second layer [1l CB] consisting of 0.1 to 5% by weight of a polyfunctional crosslinking agent having the following structure (where m is 4 to 20. R is -H1 or -CH3). , methyl methacrylate 80
99% by weight, and 1 to 20% by weight of a monofunctional unsaturated monomer copolymerizable with the third layer EC), and the 37th layer [C) further comprises n stages. (where n is 2 to 4), the molecular weight gradually decreases from the inside to the outside, and the 3N first stage monomer weight is at least '/n of the total monomer weight of the third layer. Each layer consists of 1st layer: 5-20 parts by weight, 21-55-80 parts by weight, third layer 15-40 parts by weight (base: 4100 parts by weight), and the particle size is 800-1500 parts by weight. Characteristic multilayer structure polymer composition.