CA1049185A - Surface altering agent for thermoplastic polymers - Google Patents

Abstract

ABSTRACT OF TEE DISCLOSURE

Blends of extrudable, moldable, or heat formable thermoplastic polymers with a surface altering agent for the thermoplastic polymers comprising cross-linked polymer particles having an average size of 1 to 30 microns are disclosed. Also disclosed are processes for preparing such blends. Surface characteristics of the thermoplastic polymers such as, for instance, gloss printability and scuff-resistance can thereby be changed as desired in a simple manner without the necessity of employing such conventional procedures as using inorganic flatting agents, or mechanical surface altering techniques such as calendering, or applying surface coating compositions to substrates made from said thermoplastic polymers, all of which procedures have significant drawbacks associated therewith.

Description

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This invention relates to thermoplastic polymers con-taining a surface alterir~ agent. By surface altering is meant changing the surface characteristics of the thermoplastic ~oly mer.
To achieve surface altering in thermoplastic ~olymers, -it has heretofore been the general practice to incorporate inorganic flatting agents such as calcium silicates, magnesium silicates~ amorphous silica gels, and the likeO The use of .
such inorganic particulate material has a dlsadvantage of causing detrimental effects on the physical properties of the thermo-.. . .
plastic material9 such as loss of impact strength~ toughness~
clarity~ processability, and the like. Inorganic flatting -agents also suffer from poor dispersion in many cases~
.
~ An~ther prior method af achieving surface altering ~, . . .
;~ Or thermoplastics has been by calendering, but such mechanical systems have the disadvantage of lack of uniform quality and limited utility in that they cannot be used in an extrusion process. Further disadvantages of mechanical flatting or sur-face altering are that the calendering rolls ~ust be refinished from time t~ time which is of some e~pense and incomrenience Also~ calendering is not a flexible method in that one cannot easlly vary the gloss reduction achieved; the only way to vary

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it is by changing the calendering rolls.
A different method of altering the surface of sub-strates is~ of course~ by applying a coating composition which is generally a synthetic resinous latex or dispersion of film forming po]~.er or a solution of binder in solvent. It has been suggested to achieve flatted coatings by incorporation o~ non-crosslir~ed~ incompatible polymer particles in the coating composition, but such coating systems are not useful for l~
altering the surface of thermoplastic polymers which are to l;
be subjected to an after-~reatment such as molding, heat forming, or extrusion. - I;
It is an object of the present invention to provide a simple method for uniformly altering the surface of thermo-plastic polymers. It is a further object to provide thermo-plastic polymers whose surface has been altered without affecting other physical properties. A still further object is to provide for uniform~ flexible, and economic flatting of thermopl&stic polymers. A further object is to provide thermoplastic polymers of reduced surface gloss. An additional object is to provide flatting agents which can withstand the high temperatures used - in extrusion and molding of thermoplastics~
These and other objects as will become apparent are achieved by the present invention which comprises in one aspect blends of extrudable~ moldable~ or heat formable thermoplastic polymers and a surface altering agent comprising cross-li~ed ¦
- polymer particles having an average size of 1 to 30 microns.
; In another aspect the invention comprises a method of altering the surface o~ thermoplastic polymers comprising blending ~ith the thermoplastic polymer a controlled amount of surface alter-ing agent comprising the above men~ioned cross-linked polymer

-3-particles.
The present invention, therefore, in one aspect, resides in a blend of an extrudable, moldable or heat formable thermoplastic polymer and a surface altering agent for said thermoplastic polymer, said surface altering agent comprising cross-linked particles of polymers comprising about 86-99.95%
by weight of at least one monoethylenically unsaturated monomer, about 0.05-4% by weight of at least one polyunsatura-ted cross-linking monomer, and from 0% to about 10% by weight of a latently cross-linkable addition polymerizable unsaturated monomer having one or more reactive polar groups selected from -OH, ` NH, -~-N ~ , -N=C=O, ` CHCN, -COOH, and -C~-~C-, said particles having an average size of 1 to 30 microns, said ' surface altering agent being present in an amount of from about 0.1 to 50 parts by weight per 100 parts by weight of said blend.
In another aspect, this invention resides in a ¦
method for altering the surface of extrudable, moldable or heat formable thermoplastic polymers comprising blending therewith before or during processing cross-linked particles of polymers comprising about 86-99.95% by weight of at least one monoethylenically unsaturated monomer, about 0.05-4% by I weight of at least one polyunsaturated cross-linking monomer, and from 0% to about 10% by weight of a latently cross-linkable addition polymerizable unsaturated monomer having one or more reactive polar groups selected from -OH, ` NH, -C-N ~, -N=C=O, ~ CHCN, -COOH, and -~-,C-, said particles having an average size of l to 30 microns, in an amou~t of from about 0.1 to 50 parts by weight per 100 parts by weight of the total blend.
In a further, more particular aspect, the invention -

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resides in a method as described in the immediately preceding paragraph in which the surface altering agent is prepared by polymerizing a monomer system comprising about 86-99.95% by weight of at least one monoethylenically unsaturated monomer, about 0.05-4% by weight o~ at least one polyunsaturated cross-linking monomer, and from 0% to about 10% by weight of a latently cross-linkable addition polymerizable unsaturated monomer having one or more reactive polar groups selected from -OH, ~ NH, -C-N~, -N=C=O, ~ CHCN, -COOH, and -C~-C-, in the presence of a preformed acrylic-type polymer which is soluble in said monomer system, thereby to form cross-linked polymeric particles derived from said monomer system, said particles being of average size of about 1 to 30 microns, dispersed in a continuous phase of said preformed polymer, said preformed polymer being compatible with said thermoplastic polymers.
The amount of surface altering agent included in the blend is usually about 0.1 to 50 weight parts per 100 weight parts of blend, preferably about 1 to 10 weight parts per 100 weight parts of blend. The exact amounts depend upon the par-ticular surface properties desired and other factors such asthe particular thermoplastic polymer being altered and the particular surface altering agent being employed.
Suitable thermoplastic polymers whose surfaces can be altered by this invention include the vinyl chloride poly-mers by which is meant polymers prepared from monomer systems containing at least 50% vinyl chloride, more likely over 70 or 80~ vinyl chloride, and the remainder other monomers such as propylene, vinyl acetate, ethylene and the like; acrylo-nitrile-butadiene-styrene (ABS) copolymers, methyl methacrylate-butadiene-styrene (MBS), nylons, polyethylene terephthalate, ~ -4a-.
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polyethylene, polypropylene, polycarbonate, poiyalkyl methacrylate, polyurethane, polystyrene, other thermoplastic polymers, and blends of two or more thermoplastic polymers.
The term thermoplastic polymers is defined to exclude coating systems, i.e., binder/solvent systems, and the thermoplastic polymers to be surface altered are unsuitable for use in the coating art.
The surface altering agent can be prepared by any suitable process which results in cross-linked polymer particles having an average size of 1 to 30 microns. The pre-ferred process is by an endopolymerization technique wherein the monomers that will ultimately form the particulate polymer surface altering agent are polymerized in the presence of a soluble preformed polymer which is dissolved in the above-mentioned monomers, and is selected so that phase separation takes place early in the -''''"~' .

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polymerization process. ~hen phase separation occurs, the soluble preformed polymer becomes the continuous phase and the polymerized monomers form the particulate polymer surface altering agent as the discontinuous phase, i.e., as distinct spherical particles dispersed in the soluble preformed polymer phase. The particulate surface altering agent polymer is insoluble in the so-called "soluble" polymer and the latter becomes a carrier polymer in this technique, i.e., the original preformed polymer which ~as dissolved in the monomer system remains intact and, upon polymerization of the monomer system going into the particulate polymer surface altering agent, becomes the continuous phase having dispersed therein the par- ~ .
ticulate polymers of the average particle size of 1 to 30 microns.
Suitable compatible preformed carrier polymers (soluble polymers) include polymethyl methacrylate or copolymers of methyl methacrylate with less than 20% lower alkyl acrylate units as the preferred polymers. Optionally, other co-monomers can be used in small amounts, for example, styrene, vinyl acetate, vinyl chloride, or acrylonitrile. A suitable molecular weight for the compatible preformed carrier polymer is about 10,000 to about 300,000.
The suitable monomers for the surface altering agent include about 86-99.95%, preferably about 98-99.5%, of at least one monoethylenically unsaturated monomer, about 0.05 to 4%
preferably about 0.5 to 2.0% of at least one polyunsaturated cross-linking monomer, and, optionally, up to about 10% of a polar monomer, all on a weight basis. Suitable monoethylenically unsaturated monomers are alkyl acrylates preferably having 4 to 8 carbon atoms in the alkyl, vinyl esters such as vinyl acetate, vinyl propionate, vinyl stearate and the styrenes including .
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styrene and ring-substitu-ted styrene. ~he preferred systems contain a major part of styrenes and a minor part of(C~-C8) alkyl acrylate, more preferably wherein the ratio of styrenes to CL~~C8 acrylate is at least 1.5.
While it is broadly possible to include about 0.05 -to 4% of the polyunsaturated cross-linking monomer, it is much pre~erred to use about 0.5 to 2% based on the total weight of the monomer system. While the exact amount of cross-linking monomer varies with different monomer combinations, I have found the sl~ face alterin~ properties of a particular system to vary greatly with small changes in amount of cross-li~king monomer, and therefore it is important to determine with care .`.
the exact amount of cross-linker to be used. Exemplary cross- :
linking monomers.are those formed by the reaction of acrylic or ; :
methacrylic acid with ethylene~ propylene~ butylene, or hexa-methylene glycols. In-addition~ divinyl benzene; divinyl or diallyl compounds~ such as the divinyl ethers of the above ;~
glycols; diallyl phthalate; triallyl cyanurate; and other similar .
monomers h~ving more than one polymerizable group, may be used. ~ :
Additional polyethylenically unsaturated compounds include the :~
following: divinylpyridine, divinyltoluenes~ divinylnaphthalenes~
1,3-divinylxylene~ divinylethylbenzene, divinylsulfone7 poly-vinyl or polyallyl ethers of glycol, or glycerol~ of pentaery-` thritol~ of mono- or dithio- derivatives of glycols,.and of ;.
resorcinol~ divinylketone, divinylsulfide~ allyl acrylate~ :~
diallyl maleate~ diallyl fumarate, diallyl succinate, diallyl carbonate~ diallyl malonate, diallyl oxalate~ diallyl adipate, ~ .
. diallyl sebacate, divinylsebacate~ diallyl tartrate, di.allyl `. silicate, triallyl tricarballylate~ allyl methacrylate, triallyl citrate, triallyl phosphate, N,N'-methlenediacrylamide, N,N'- .
ethylenediacrylamide, 1,2-di(a-methylmethylene sulfonamido)-6 .~.. .
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-~049~85 ethylene~ trivinylbenzene~ trivinylnaphthalene~ and polyvinyl-anthracenes Substantially any monomers having more than one addition-polymerizable olefinic group are useful. The preferred I cross-linXing agents have the formula:

CH2 ~ ~ - ~ - OR

wherein Rl is H or CH3- and R is an ethylenically ~msaturated radical. Where such compounds are substituted, the chain length of such substitutions is not critical, but usually varies from about 1 to 20~ preferably about 1 to 4 carbon atoms~
Optionally, the polymer particles can be made infusible by secondary or latent cross-linking by including up to about 10 weight percent polar mo~omer, Generally, secondary or latent cross-linking would occur during such steps as hot roll milling, Banbury mixing or extrusion of the polymer mass The polar monomers whicll are suitable for this function include those that are residues of acrylics, and can be best exemplified by the following: acrylic acid; methacrylic acid; acrylamide;
methacrylamides; epoxyalkyl acrylates or methacrylates, eOg., glycidyl methacrylate; monoacrylic acid esters of glycols;
hydroxyalkyl acrylates or methacrylates, isocyanatoalkyl acry-lates and aminoalkyl acrylates or methacrylates, as well as other compoundsdescribed below.

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Examples of the secon~ry or li~tent cross-linkinr7 reactions ~hich are possible using haat and/or catalysis~are:
:. > NH + HO~ ~ >N~--CH-CH2 + HOOC- ~ -CH-CH2-O-CO-

5-CH-C/H2 + H-N- > -ICE-c~2 N
~ H :

-CH-CH2 + -CNHCH20R - ~ -CH-CH2-N~
: O OH CH20R

_ ~-CH2 + -C-~CH20H ~ fH-CH2-OH

_CH-CH2 ~ -C~-/CH2 >

- CH2 H~

2 (-cl~HcH2oH) > -9NH5H2oCH2NHC-~ ~0 ~[

10~N~C=O + HOC~ NH-~-OC--~=C=O + H~ _ 1O H~
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~C~491~35 Addition polymcrizable unsaturated monomers containing such groups are well known in the art, examples being isocyanates such as isocyanatoethyl methacrylate, epoxy compounds such as glycidyl methacrylate~ aminoalkyl compounds such as methyl-aminoethyl methacrylate~ and t-butylaminoethyl methacrylate, amides such as methacrylamide, guanamines such as 4-penteno-guanamine, hydroxyalkyl esters such as hydroxyproFyl meth-acrylate and hydroxyethyl methacrylate~ nitriles such as methacrylonitrile, N-alkoxyalkylamides such as methoxymethyl methacrylamide, hydroxyal'~yl amides such as N-methylol meth-acrylamide, the analogs of the above methacrylic acid derivatives with other unsaturated acids such as acrylic acid and itaconic acid~ such acids themselves; dic~rboxylic acids such as maleic acid and half esters and half amides thereof~ vinyl ethers of glycols such as ethylene glycol, and so forth.
. As may be seen, the latently cross~ able add.ition polymerizable unsaturated monomers have reactive polar groups selected from those including -OH,> NH, -~-N<, -N=C=O,~ CHCN, _COOH~ and -C -~ - .

While it is not usually necessary to provide for such secondary cross-linking, in systems where it is necessary or is preferred, the secondary cross-linking monomers are present in amounts of from 0.05 to 10%, preferably from 0 1 to 3~ by weight, based on the total monomers that form the particulate polymer~
When such monomers are utilized~ and contain alkyl groups, the groups usually contain from about 1 to 20~ preferably about 1 to ~ carbon atoms~ The preferred secondary cross-linking co-monomer is methacrylic acid and is usually utilized in amounts : of less than 2~ by weightO
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An alternative method to this endopolymerization teclmique for preparation of the surface altering agent com-prises introducing the monomers in water containing a suspending !
agent under conditions to form suspended monomer globules having an average size of about 1 to 30 microns, and then polymerizing and isolating by conventional methods.
Whether the particles are prepared by the endopoly-merization technique or the modified suspension technique~ the polymerization is conveniently effected by conventional free radical pol~rmerization catalysts, such as redox catalysts and ~-peroxy compo~lds~ heat or irradiation. In general, these catalysts are present in amounts of from about 0.02 to 1.0, il preferably from about 0.2 to 0.5 weight percent, based on the 1 -total monomers that form the surface altering agent particulate polymer. The catalyst may be a combination of both high and low temperature components if it is desired that the above-noted secondary or post polymerization cross-linking be enhanced.
Exemplary catalysts include benzoyl peroxide, acetyl peroxide~
i t-butyl peracetate~ dicumyl peroxide~ azoisobutyronitrile (AIBN), t-butyl hydroperoxid~, and t-butyl peroxy pivalate. Moreover, ¦-~
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either heat or irradiation, or a single compound catalyst in com-bination with heat and/or irradiation may be utilized. Further, it should be noted that metal accelerators are o~ten useful when irradiation catalysis is used~ for example wqth the use of ultra-violet light. Heat or radiation functions can be used in combin-ation with other free-radical generating materials.
If the surface altering agent polymer particles are below an a~er~ge size of 1 micron they do not have the desired effect on the surface Or the thermoplastic polymers, i.e., gloss reduction cr anti-blocking. When the avera~e particle size is ,, ' '~ ~ ' ~4~ S ~ ~

above 30 microns, the surface texture of the extruded or molded thermop'l~stic pol~mer article becomes objectionably rough and unattractive for most applications, although such articles could be useful, possibly, for certain speciality applications. The 5 particle size distribution can be either narrow or broad, and by' proper choice of particle size range and distribution, vary-ing surface effects can be obtained. For example, for print-ability a narrow distribution is preferred, whereas for gloss reduction, a broader distribution is preferred.
If the surface altering agent is prepared by the endo-polymerization technique~ it is a solid material at room temperature, in the form of a solid composite of the surface altering particles in a matrix of the continuous phase carrier polymer. The solid composite is preferably granulated and thereafter blended with the thermoplastic polymer in the de sired amounts before or during processing of the thermoplastic.
By proper selection of monomers going into the surface altering agent polymeric particles it is possible to achieve a desired refractive indexO For applications wherein clarity of the thermoplastic polymer is necessary, it is preferrea to select the monomers so that the cross-linked particles have a ' refractive index within about 0.'005 units of the refractive ' index of the thermoplastic/carrier polymer blendO In systems wherein clarity is not necessary or desired, the refractive index of the surface altering agent polymer particle is not important.
~ The surface altering properties achievable by the ; present in~ention include flatting, anti~blocking~ improved printability, scuff resistance, or hiding of surface imper-fections of thermoplastics. By varying the amounts of surface - . , . , . ... , . , . , , , lr .
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albering agents, one can achieve anti-blocking without necess-arily flatting the thermoplastic materialO
The blends of the invention are useful as single layer sheets or as laminate or other molded~ cast~ extruded~ or heat formed articlesO The blends can further include dyes, pigments, colorants, stabilizers~ plasticizers~ fillers, and other con-ventional additives The blend can be thermo~ormed without affecting the surface alteration.
When the surface altering agent is prepared ~y the endopolymerization process~ the soluble carrier polymer, i.e., the preformed polymer, should be compatible with the thermo-plastic polymer which is to be altered. For example~ uhen it is desired to prepare flatted PV~ sheet~ one preferred surface altering agent/carrier combination is styrene/butyl acrylate/
ethyl acrylate/allyl methacrylate (61/3~/305/1.5) as surface altering agent in methyl methacrylate/ethyl acrylate (91/9) Garrier polymer.
The following Examples are presented to illustrate ~ several embodiments of the invention bu~ it should be under-stood that the invention is not in any way limited to the embodiments illustrated.

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.1 91~35 EXA~lPLE 1 This example shows preparation of a surface altering i agent in a preformed polymer. 26.7Y pounds of a preformedj polymer o~ ethyl acrylate/methyl methacrylate copolymer (9/9' by weight) is dissolved in a monomer system comprisin~ 4~.17 pounds of styrene monom~r, 2L~o62 pounds of _-butyl acrylate, and 2.90 pounds of ethyl acrylate at 50oC. After two hours of stirring~ the preformed polymar is completely dissolved in the monomer system. After the solution has been cooled to 30~C., the follo~.ring ingredients are then added with appropriate stirring to insure that each is completely mixed before the next is added: 1.085 pounds of allyl methacrylate as cross-linking agent for the surface altering agent, 0.0009 pounds of oxalic acid, 0.0725 pounds Of tertiary-dodecylm3rcaptan, 0.1449 pounds of t-butyl peroxypivalate, 0.0725 pounds of 25% acetyl peroxide solution in dimethyl phthalate, and 0.1449 pounds of dicumyl peroxide. This mixture is then polymerized in an air circulating oven for 16 hours at 660C., 2 hours at 800C., a~d then 6 hours at 120C. The resulting 1/2" slab of polymer is broken and further granulated intv particles capable of passing through a 5/16" mesh screen. The endopolymeric surface altering agent is characterized by a particle size range of about 1 to 35 microns in diameter, as determined by elsctron microscopy, the average particle size being about 1.5 microns. The acetone extractables, as an indication of degree of cross-linking, is 41% by weight~ and the s-.~elling ratio as an indication of crossiink density is 7Ø ;
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This example illustrates a blend of a surface altering agent with a thermoplastic polymer. T~o parts by weight of the I surface altering agent/carrier polymer composition in granular form prepared in Example 1 and 100 parts by weight of polyvinyl chloride having a K value of 69 and containing therein 50 parts of di(2-ethylhe~l) phthalate (DOP) as plasticizer, 2 parts by weight of dibutyltin mercaptoacetate stabilizer and 0.25 parts -by weight of stearic acid lubricant are mixed together and kneaded on a roll mill for 5 minutes at 3250C. at a speed differential of 20/20 RPM to form a 15 mil thick film. The surface of the film in contact with the rolls is painted black to eliminate reflection from the~second surface and the specu-lar gloss measured at 600 angle of incidence~ For comparison, a 15 mil thick film containing 2 parts by weight of an inorganic su~face altering a~ent (amorphous silica) prepare~ b~J the same working conditions and a 15 mil thick film containing no surface . ; altering agents, polymeric or inorganic in nature, are pre-; pared and measured~ The results are shown in Table 1.

. Clarity . % White %
Additive600 Gloss (%) Li~ht TransO Haze : Thls invention1303 86.3 13.7 Amorphous Silica Gel 38.5 83~5 98 Unmodified Control 65.7 83.0 16,2 .

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This example shows a blend of surface alterin~ agent and rigid (unplasticized) PVC. 5 parts by weight of surface I altering agent composition from Example 1 in granular form and 100 parts by ~eight of polyvinyl chloride having a K value of 61 and containing therein 12 parts by weight of an MBS type impact modifier (~cryloid ~ KM 611), 3 parts by weight of an acrylic processing aid (Acryloid ~ K120N), 2 parts by weight of dibutyltin mercaptoace-tate, 0.75 parts by weight of glycerol monostearate an~ 0.75 parts by weight of partially saponified ester are mixed together and kneaded by a roll for minutes at 3500F. at a speed differential of 20/20 RPM. A
35 mil sample is removed from the roll mill, back painted black to eliminate reflection from the second surface and the specular.;
gloss measured at 600 angle of incidence. The balance o. the stock is milled Ior an additional 3 minutes at 3500Fo af-ter ~ .
: which the kneaded mixture is molded into a 0.100" sheet at 3500F.
70 tons pressure ~ith a cycle of.3 min. preheat/2 minutes press/
.:
~ 3 minutes cooling~ The molded sheet is tested for V-notch Izod : 20 impact strength, and further subjected to measurement for light transparency in comparison with molded sheet containing 5 parts of an inorganic surface-altering agent (amorphous silica gels) .
prepared by the same working conditions and a molded sheet con-taining no surface altering agent~ polymeric or inorganic in ~5 natureO The results are shown in Table 2 :

Izod Impact Clarit 600 Gloss Strength Y
Additivo . ~ ft -lb.~in. 7~WL ~aze .:
This invention 5 5. 515. 6 78 .1 9 . 2 . Amorphous Silica 5 7.80.72 37.1 100.0 : Gel Unmodified Control 0 13~9 22.5 73.0 11.1 :

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As is apparent from the above table, the surface alter-ing agent composition of this invention provides superiGr gloss reduction, impact s-trength and clarity over the amorphous silica gels.

The procedure and compositions disclosed in Example 1 are followed except that the amounts of styrene monomer and n-butyl acrylate monomer are 61.50 pounds and 7.29 pounds, respectively, and tes-ted for gloss reduction according to the procedure used in Example 1, Table 1.
The results are a 60 g~oss (%) of 18.5.

The procedure and compositions disclosed in Example 1 are followed except that the amount of s-tyrene monomer is 41.17 pounds and 27.62 pounds of 2-ethylhexylacrylate are substituted for the butyl acrylate, and tested for gloss reduc-tion according to the procedure used in Example 1, Table 1. The resul-ts are a 60 gloss (%) of 11Ø ''"' This example illustrates a suspension polymerization process for preparing the surface altering agent of the invention in a carrier polymer (endopolymer). The mixing procedure disclosed in Example 1 is followed using as ;
the preformed polymer 266.2 grams of a copolymer o-f about I0% ethyl acrylate copolymerized with about 90% of methyl methacrylate. The monomer system in which the preformed ' polymer is dissolved cnnsists o-f 430.2 grams of styrene monomer, 240.6 grams of n-butyl acrylate, and 27.62 grams of ethyl acrylate. The following ingredients are added to the syrup: 21.70 grams of allyl methacrylate, 7.202 ~ - 16 -,' .
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~L91~5 grams of t-butyl peroxypivalate, and 7.202 grams of lauryl peroxide. In a suitable reaction vessel a mixture of 986.4 grams of deioni~ed water, u.86~ grams of Amberlite W-l suspending agent (Rohm and Haas Company) 1.380 grams of sodium nitrate, 16a -:, . . . , :: .
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: :' and 1.380 grams of potassium chloride is prepared. The monomer/polymer solution is then pumped into the vessel containing the aqueous solution. The mix-ture is sub-jected to intermittent agitation to form a stable suspen-sion. The suspension is stirred at 300 rpm and polymeri-zed at 70 C. for l hour, 80C for l hour and 90C. for 1 hour. The product suspension is cooled and isolated, and the resulting endopolymer/carrier beads are mostly between 0.085 and 0.0425 inches in diameter. The endo-' ' 'polymer is characterized by particle polymer spheres ranglng from l to 33 microns in diameter with an average size of 6. The surface altering agent prepared is tested for gloss reduction according to the procedure used in Example 1, Table 1. The results are a 60 gloss (%) of 12Ø
-This example illustrates a suspension process for preparing the surface altering agent particles without employing a carrier polymer. In a suitable reaction vessel a mixture of 760 grams of deionized water, 30.0 grams of an 8% aqueous solution of hydroxyethyl cellu-lose, 4.00 grams of Acrysol~ GS s~spending agent (sodium polyacrylate from Rohm and Haas Company), 0.300 grams of "Pharmagel"* (gelatin), and 4.00 grams of sodium chloride is stirred unitl all components have dissolved.
Separately a mixture of 266 grams of n-bu-tyl acrylate, 478 grams of styrene, 32.0 grams of eth~l acrylate f 24.0 grams of allyl methacrylate, 8.00 grams of benzoyl perox-ide, and 8.00 grams of lauryl peroxide is prepared. This monomer mixture is added to the aqueous solution, and the agitator blade is positioned at the interface between -the aqueous and organic phases. The mixt~re is submitted to , ,~ ~ ., , . , . . .. : ., , :

9~5 to intermittent agitation to form a stable suspension.
The suspension is stirred at 300 rpm and heated to 75C. over a 40 minu-te period. The polymerization is completed - 17a-* Trademark for spe~ially purified gelatin.

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using the following time/temperature cycle~ hours at 750C., 1 hour at 830C.~. 1 hour at 91C., and 1 hour at.97~C.
The product suspension is cooled and isolated by methods known in the art. The resulting polymer particle range from 1 to 30 :.
5 microns in diameter~ with an average size of 12 microns. The surface altering agent prepared is tested for gloss reduction 1 according to the procedure used in Example 1. The results are a 600 gloss (%) of 17.0 j:
EXAMPLE 8 l~
~he mixing procedure disclosed in Example 1 is followed 1- .
dissolving 888 grams of the same carrier polymer in a monomer system consisting Or 1~6~ grams of styrene monomer, 816 grams of n-butyl acrylate, and 96 grams of ethyl acrylate, then the following ingredients are added to the cooled syrup: 11.9 grams ~ .
of 1,3-butylene glycol dimethacrylate, 2.~ grams Or tertiar~
dodecylmercaptan~ 0.86 grams of 2.8% aqueous oxalic acid, ~.8 :¦
grams of t-butyl peroxypivalate~ 2.~ grams of 25% acetyl per- i:. :
` oxide solution in dimethyl phthalate~ and ~.8 grams of dicumyl ' .
peroxide. The resultant mixture is placed in a bag container I .
and bulk polymerized in an air circulating oven for 16 hours :.:
at 66~C.~ 2 hours at 800C. a and then 6 hours at 120C. After ~-. ..
the b.ag is removed from the resulting opaque 1/2" slab of polym2r the slab is broken and further granulated into particles capable . ~ .
Or passing through a 5/16" mesh screen~ and tested for gloss : --:' 25 reduction according to the procedure used in Example 1. The results are a 60 gloss (~) of 16Ø .. ~
~ EXAMPLE 9 .
The procedure and compositions disclosed in Example 6 .
.: are followed except that 5.9 grams Or 1~3-butylene glycol di-acrylate is used in place of the 1~3-butylene glycol dimeth- ' acrylate, and test~d for gloss reduction according to the :

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10~9~1L85 procedure used in Example 1, Table 1. The results are a gloss (%) of 16Ø

The procedure and compositions disclosed in Example

6 are followed except that 11.9 grams of trimethylpropane trimethacrylate is used in place o-f the 1,3-butylene gly- :
col dimethacrylate and tested for gloss reduction accord ing to the procedure used in Example 1, Table 1. The results are a 60 gloss ~) of 14Ø

The procedur~ and compositions disclosed in Example 6 are followed except that 2.~ grams of divinylbenzene is used in place of the 1,3-butylene glycol dimethacrylate, and tested for gloss reduction according to the procedure used in Example 1, Table 1. The results are a 60 gloss (%) of 20Ø
EXAMP~E 12 (Comparative) ~ his example shows the importance of selecting -the proper amount of cross~linking monomer, and its relation to properties obtained.
A. The procedure of Example 1 is followed only varying the amount of cross-linking agent, allyl methacry-late, and the following Table gives resul-ts of acetone extractables test swelling ratio, -60 gloss, and disper-sion .

., :
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~; ! ' ! ' 1, ~0491 % Extractables -.
% Cross-linker ~27% of Soluble, .
In Monomer Preformed Carrier Swelling 60~
Mixture Polymer) Ratio~loss Dis~er_ion 100 _~3 Excellent -5 . 78.5 44 56 , 0.75 58.9 16.~ 71 , .
1 51.2 10.3 16 ` "
1.5 39.2 6.~ 12 Grainy ¦~
2 29.9 4.7 16 Undispersed 3 30.6 ~.6 ~2 .
B. Surface altaring agent was prepared by the carrier l- -,.: .
- polymer technique of Example 1 but with styrene and divinyl benzene as the sole monomers, and was incorporated in the same . . .
15 manner in PVC. By varying the ratio of styrene to cross- .~ -linking monomer, varying results were ob~ained. At from 0 to -:
. .
. O.1% crosslinker in the mono~er mixture, the surface altering agent was well dispersed in the PVC, and the 600 gloss was ~ :
reduced from 91 for the PVC without surface altering agent, to .
. 20 84~ 76 and 58 respectively ~or 0, 0.05 and 0.1% cross-linker. :.
At 0.5 to 1~ cross-li~ker the dispersibility was poor to very . poor and at 3 and 5% cross-linker~ the surface altering agent .. .
could not be dispersed at all and the test sheets had large visible particles which indicated gross heterogeneity and lack of'SurIace sltering'as defined in this specificaticn.

. '. ~: ' '. .

'.; , `: `" ' :'., ~, .

Claims (18)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A blend of an extrudable t moldable or heat formable thermoplastic polymer and a surface altering agent for said thermoplastic polymer, said surface altering agent comprising cross-linked particles of polymers comprising about 86-99.95% by weight of at least one monoethylenically unsaturated monomer, about 0.05-4% by weight of at least one polyunsaturated cross-linking monomer, and from 0% to about 10% by weight of a latently cross-linkable addition polymer-izable unsaturated monomer having one or more reactive polar groups selected from -OH, > NH, <, -N=C=O, >CHCN, -COOH, and , said particles having an average size of 1 to 30 microns, said surface altering agent being present in an amount of from about 0.1 to 50 parts by weight per 100 parts by weight of said blend.

2. The composition of claim 1 wherein said particles have a refractive index within about 0.005 units of the refractive index of the thermoplastic polymer.

3. The composition of claim 1 wherein the cross-linked polymer contains about 0.5 to 2 percent of cross-linking monomer units.

4. The composition of claim 1 wherein said cross-linked polymer contains units from styrene or a ring-substituted styrene, a C4-C8 alkyl acrylate and a cross-linking agent of the formula:

wherein R1 is H or CH3- and R is an ethylenically unsaturated radical.

5. The composition of claim 4 wherein the ratio of styrene or ring-substituted styrene to C4-C8 alkyl acrylates is at least 1.5:1.

6. The composition of claim 5 wherein the ratio of cross-linking agent to total units is 0.5/100 to 2/100.

7. The composition of claim 1 wherein said surface altering agent is prepared by polymerizing a monomer system comprising monomers as set forth in claim 1, which monomer system has a preformed acrylic-type polymer dissolved therein to form cross-linked surface altering agent polymeric parti-cles of average size of about 1 to 30 microns dispersed in a continuous phase of said preformed polymer, said preformed polymer being compatible with the thermoplastic polymer being altered.

8. The composition of claim 1 wherein the cross-linked polymeric surface altering agent is prepared by dis-persing a monomer system in water in droplets of average size of 1 to 30 microns, heating to polymerize, and isolating the resultant cross-linked polymeric surface altering agent having an average particle size of 1 to 30 microns, said monomer system comprising monomers as set forth in claim 1.

9. The composition of claim 1 wherein said blend can be thermoformed without affecting the surface alteration.

10. The composition of claim 1 in the form of an extruded article, a sheet, an injected molded article, a blow molded article, a calendered sheet or film, or a lamina.

11. The composition of claim 10 wherein said surface altering agent comprises about 1 to 10 parts per 100 parts of blend.

12. The composition of claim 2 wherein said thermoplastic polymer contains at least 80% vinyl chloride units.

13. The composition of claim 1 in the form of a flatted article.

14. The composition of claim l in the form of an article of improved scuff-resistance.

15. The composition of claim 1 in the form of an article of improved printability.

16. The composition of claim 1 in the form of an article having anti-blocking properties.

17. A method for altering the surface of extrudable, moldable or heat formable thermoplastic polymers comprising blending therewith before or during processing cross-linked particles of polymers comprising about 86-99.95% by weight of at least one monoethylenically unsaturated monomer, about 0.05-4% by weight of at least one polyunsaturated cross-linking monomer, and from 0% to about 10% by weight of a latently cross-linkable addition polymerizable unsaturated monomer having one or more reactive polar groups selected from -OH, >NH< <, -N=C=O, >CHCN, -COOH, and , said particles having an average size of 1 to 30 microns, in an amount of from about 0.1 to 50 parts by weight per 100 parts by weight of the total blend.

18. The method of claim 17 wherein said surface altering agent is prepared by polymerizing a monomer system comprising monomers as recited in claim l in the presence of a preformed acrylic-type polymer which is soluble in said monomer system, thereby to form cross-linked polymeric particles derived from said monomer system, said particles being of average size of about 1 to 30 microns, dispersed in a continu-ous phase of said preformed polymer, said preformed polymer being compatible with said thermoplastic polymers.