Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-10-04
2002-02-19
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S085000, C525S301000, C525S303000, C524S504000, C526S319000
Reexamination Certificate
active
06348542
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to multiphase structured polymer particles, and relates to a method of manufacturing these multiphase structured polymer particles, and their uses. More specifically, the invention. relates to multiphase structured polymer particles comprising at least two rubber component phases (I) which are mutually adjacent to each other and have different monomer compositions, and a resin phase (II) which has thermoplasticity at least in its outermost part. The invention relates to multiphase structured polymer particles which, if a monomer mixture (i) forming the rubber component phase (I) fulfils specific conditions, are able to exhibit specific functions, i.e., they not only excel in flexibility, but also excel in transparency and elastic recovery properties (excellent permanent set characteristics). It further relates to a method of manufacturing same, and to a molding material and film or sheet comprising. these multiphase structured polymer particles.
2. Description of the Related Art
Multiphase structured polymer particles, also referred to as core-shell type polymers, contain an inner phase of a rubber component and an outermost phase of a thermoplastic resin component part, and are used for the reforming of thermoplastic resins such as polyvinyl chloride, polyester and acrylic resins, etc. Some of them are known to be useful as modifiers to impart toughness (U.S. Pat. Nos. 4,730,023, 3,808,180, 3,843,753, and Japanese Provisional Patent Publication No. 5-17654(1993)).
However, although molded products which excel in flexibility are obtained when these multiphase structured polymer particles used for the purpose of imparting toughness are formed independently, their moldability is poor as there is little thermoplastic resin component which constitutes the outermost phase, and they are therefore not very practical.
If moldability is improved by increasing the thermoplastic resin component of these multiphase structured polymer particles, flexibility is sacrificed, and elastic recovery properties (low permanent set properties) decrease.
Further, it is common in multiphase structured polymer particles to make the refractive index of each phase of the multiphase structured polymer particles coincide in order to improve transparency. However, if the glass transition point of the rubber component phase is lowered in order to recover the flexibility which was sacrificed, it becomes difficult to make the refractive index of each phase coincide, and a good transparency is not obtained.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide multiphase structured polymer particles which give a molded product having excellent elastic recovery properties (low permanent set characteristics) and transparency when they are formed into a molded product, while maintaining good moldability. It is another object of this invention to provide a method of manufacturing multiphase structured polymer particles. It is yet another object of this invention to provide molding applications of these multiphase structured polymer particles.
In order to solve the above-mentioned problems, the inventors performed various investigations. It was found that if the molecular weight of the thermoplastic resin component which constitutes the outermost phase of the multiphase structured polymer particles, the average particle size of the particles and the solubility in water of the monomer forming the core component phase satisfied certain conditions, excellent elastic recovery properties and transparency were obtained. Further considerations led to the formulation of the present invention.
One object of this invention as stated hereabove is achieved to provide multiphase structured polymer particles (referred to hereafter in some cases as multiphase structured polymer particles (A)) which:
(1) comprise at least three phases comprising at least two of the following inner rubber component phases (I), and at least one of the following thermoplastic resin component phases (II) in at least the outermost part, wherein
(2) the rubber component phases (I) are polymer phases formed by copolymerization of a monomer mixture (i) comprising 50-99.99 wt % of an acrylic acid ester, and 49.99-0 wt % of another monofunctional monomer together with 0.01-10 wt % of a polyfunctional monomer capable of copolymerization with the acrylic acid ester, at least two of the rubber component phases (I) being mutually adjacent to each other and having mutually different monomer unit compositions,
(3) the thermoplastic resin component phase (II) is formed by copolymerization of a monomer mixture (ii) comprising 40-99 wt % of a methacrylic acid ester, and 60-1 wt % of another monomer capable of copolymerization with the methacrylic acid ester,
(4) the polymer which constitutes the phase situated in the outermost part among the thermoplastic resin component phases (II) has a number average molecular weight of 30,000 or less measured by the GPC method,
(5) the ratio of the total weight of the rubber component phases (I) and the total weight of the thermoplastic resin component phase (II) is in the range of 30/70-80/20 expressed as phase (I)/phase (II),
(6) the average particle diameter is 150 nm or less,
(7) for all of those phases constituting the rubber component phases (I) which are mutually adjacent to each other, the absolute value of the difference of the solubility A
n
in water of the monomer mixture forming the nth phase from the innermost part, and the solubility A
n+1
in water of the monomer mixture forming the n+1th phase adjacent to it, is 0.36 or less (where A
n
is the sum of the products of the weight fraction of each monomer of the monomer mixture forming the nth phase and the solubility of the monomer in water at 20° C. (g/100 g H
2
O), and A
n+1
is the sum of the products of the weight fraction of each monomer of the monomer mixture forming the n+1th phase and the solubility of the monomer in water at 20° C. (g/100 g H
2
O), and
(8) the absolute value of the difference of the refractive index n
d
(I) of any of the phases included in the rubber component phases (I), and the refractive index n
d
(II) of any of the phases included in the thermoplastic resin component phase (II), is less than 0.005 for all phase combinations.
Other objects of the invention as stated hereabove are achieved by
(1) to provide a method of manufacturing multiphase structured polymer particles comprising at least three phases comprising at least two inner rubber component phases (I) which are mutually adjacent to each other and have mutually different monomer unit compositions, and at least one thermoplastic resin component phase (II) in at least the outermost part, by forming phases from the center part to the outer part by performing polymerization reaction steps (a) for forming the rubber component phases (I) and polymerization reaction steps (b) for forming the thermoplastic component phase (II) in a predetermined sequence,
(2) in the polymerization reaction steps (a), copolymerizing a monomer mixture (i) comprising 50-99.99 wt % of an acrylic acid ester, and 49.99-0 wt % of another monofunctional monomer together with 0.01-10 wt % of a polyfunctional monomer capable of copolymerization with the acrylic acid ester, at least two of the polymerization reaction steps (a) being a series of polymerization reaction steps using mutually different monomer mixture (i),
(3) in the polymerization reaction steps (a), selecting the type and amount of monomers in the monomer mixture so that, for all of those phases included in the rubber component phases (I) which are mutually adjacent to each other, the absolute value of the difference of the solubility A
n
in water of the monomer mixture forming the nth phase from the innermost part, and the solubility A
n+1
in water of the monomer mixture forming the n+1th phase adjacent to it, is 0.36 or less (where A
n
is the sum of the products of the weight fraction of each monomer of the monome
Hoshiba Takao
Katoh Yuichi
Naruse Tatsuya
Terada Kazutoshi
Yamashita Takashi
Asinovsky Olga
Kuraray Co. Ltd.
Seidleck James J.
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