阅读说明：本技术 乙酸乙烯酯共聚物作为低收缩添加剂的用途 (Use of vinyl acetate copolymers as low profile additives ) 是由 马库斯·本杰明·班瓦尔特 迈克尔·托比亚斯·扎尔卡 于 2019-05-15 设计创作，主要内容包括：本发明涉及乙酸乙烯酯乙酸异丙烯酯共聚物作为低收缩添加剂(LPA)的用途,其特征在于,所述乙酸乙烯酯乙酸异丙烯酯共聚物是基于2wt％-98wt％的乙酸乙烯酯、2wt％-98wt％的乙酸异丙烯酯和可选的一种或多种其它乙烯型不饱和单体,各自都相对于所述乙酸乙烯酯乙酸异丙烯酯共聚物的总重量。(The invention relates to the use of a vinyl acetate isopropenyl copolymer as a Low Profile Additive (LPA), characterized in that the vinyl acetate isopropenyl copolymer is based on 2% to 98% by weight of vinyl acetate, 2% to 98% by weight of isopropenyl acetate and optionally one or more other ethylenically unsaturated monomers, each relative to the total weight of the vinyl acetate isopropenyl copolymer.)

1. Use of a vinyl acetate-isopropenyl acetate copolymer as a low profile additive, characterized in that the vinyl acetate-isopropenyl acetate copolymer is based on 2% to 98% by weight of vinyl acetate, 2% to 98% by weight of isopropenyl acetate and optionally one or more other ethylenically unsaturated monomers, in each case based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

2. Use of a vinyl acetate isopropenyl acetate copolymer as a low profile additive according to claim 1, characterized in that the vinyl acetate isopropenyl acetate copolymer comprises from 50 to 98 wt% of vinyl acetate, based on the total weight of the vinyl acetate isopropenyl acetate copolymer.

3. Use of a vinyl acetate-isopropenyl acetate copolymer as a low profile additive according to claim 1 or 2, characterized in that the vinyl acetate-isopropenyl acetate copolymer comprises from 2 wt% to 50 wt% of isopropenyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

4. Use of a vinyl acetate-isopropenyl acetate copolymer according to any of claims 1-3 as a low profile additive, characterized in that the vinyl acetate-isopropenyl acetate copolymer comprises ≥ 95 wt% of vinyl acetate and isopropenyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

5. Use of a vinyl acetate-isopropenyl acetate copolymer according to any of claims 1-4 as a low profile additive, characterized in that the one or more additional ethylenically unsaturated monomers are selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulphonic acids and ethylenically unsaturated phosphonic acids and salts of the above mentioned acids.

6. Use of a vinyl acetate-isopropenyl acetate copolymer as low profile additive according to any of claims 1-5, characterized in that the vinyl acetate-isopropenyl acetate copolymer has a glass transition temperature Tg (as determined by differential scanning calorimetry) of 20-70 ℃.

7. Use of a vinyl acetate-isopropenyl acetate copolymer as low profile additive according to any of claims 1-6, wherein the vinyl acetate-isopropenyl acetate copolymer has a molecular weight Mw (determined by size exclusion chromatography using polystyrene standards at 60 ℃ in THF) of 2,000-750,000 g/mol.

8. Use of a vinyl acetate-isopropenyl acetate copolymer according to any of claims 1-7 as a low profile additive, characterized in that it has a molecular weight of 1-100mPasViscosity (by)Method, determined according to DIN 53015 at 20 ℃ in 10% strength solution in ethyl acetate).

9. A free-radically crosslinkable polymer composition comprising

a) At least one crosslinkable unsaturated polyester resin or at least one vinyl ester resin;

b) at least one monomer having an ethylenically unsaturated group,

c) at least one initiator, characterized in that one or more vinyl acetate-isopropenyl acetate copolymers according to any of claims 1 to 8 are additionally present.

10. A composite component obtainable by curing the free-radical crosslinkable polymer composition according to claim 9.

Technical Field

The present invention relates to the use of vinyl acetate copolymers as Low Profile Additive (LPA), to free-radically crosslinkable polymer compositions comprising the above-mentioned low profile additive and to composite components obtainable therefrom.

Background

Free-radically crosslinkable polymer compositions based on, for example, unsaturated polyester resins (UP resins) are frequently used for producing composite components. Unsaturated polyester resins are generally polycondensates of dicarboxylic acids (anhydrides) and polyols. Further components of the free-radical crosslinkable polymer composition are generally ethylenically unsaturated monomers, such as styrene or methacrylate monomers, in order to dissolve the crosslinkable polymer and convert the free-radical crosslinkable polymer composition into a flowable mass. In order to initiate crosslinking of the polymer composition, it is possible to use, for example, peroxides or hydrogen peroxide as initiator. Furthermore, such a radical crosslinkable polymer composition can optionally also comprise fibrous materials, such as glass fibers, carbon fibers, natural fibers or corresponding fiber mats (fiber-reinforced plastic composite ═ FRP composite), which lead to a reinforcement of the composite component which can be obtained by curing the radical crosslinkable polymer composition. The free-radically crosslinkable polymer compositions can also be used, for example, for producing filled solid surfaces or artificial stone (engineered stone) products-composites composed of unsaturated polyester resins or acrylate resins and mineral fillers such as silica or Aluminum Trihydrate (ATH).

One problem associated with the processing of free-radical crosslinkable polymer compositions into composite components, in particular reinforcing or filling components or materials, is the volume shrinkage during curing of the polymer composition. In order to reduce shrinkage during curing, shrinkage reducing additives, known as Low Profile Additives (LPAs), are therefore added to the free-radical crosslinkable polymer compositions. The low profile additive can reduce shrinkage during curing, dissipate residual stress, reduce microcrack formation, and facilitate compliance with manufacturing tolerances. Furthermore, it is a desirable aspect that the low profile additive also improves the surface quality of the composite component (in particular, a class a surface should be reached) and that the imprint of the reinforcing fibers on the surface of the component ("fiber print through") should also be suppressed.

As low-profile additives, thermoplastics such as polystyrene, polymethyl methacrylate, saturated polyesters or polyvinyl acetate are frequently used. For example, low profile additives based on polyvinyl acetate and optionally carboxyl-functional monomers are described in DE-A2163089, US 3,718,714A or WO 2007/125035A 1. Polyvinyl acetate shows significantly lower shrinkage values and significantly better surface quality of the components compared to polystyrene and polymethyl methacrylate, with significantly better mechanical properties compared to saturated polyester LPA.

A further problem is that low profile additives can adversely affect the static mechanical properties, e.g., flexural and tensile strength, of the cured composite component. In order to reduce such an influence, it is advantageous for the low profile additive to exhibit a desired degree of shrinkage reduction effect at a very small addition amount. For this reason, there is a need for low profile additives that have a stronger shrinkage reduction effect and allow the same shrinkage control at lower add-on levels or make possible lower shrinkage of the component and better surface quality at the same add-on levels.

In order to increase the effectiveness of the low profile additives, it is advisable to add specific low molecular weight compounds. For this purpose, EP 0031434 recommends the use of low molecular weight epoxidized compounds, for example epoxidized plasticizers. Such low molecular weight additives do not participate in curing and remain in the component and can migrate out of the component over time, which can lead to increased VOC values (VOC ═ volatile organic components) or FOG values (FOG ═ fogging; out-gassing (outgassing) known as condensable species) and impaired mechanical properties. In addition, such low molecular weight additives can compromise the blocking stability of the composition, making logistics, transportation and storage rather complicated and expensive.

Disclosure of Invention

In view of this background, it is an object of the present invention to provide Low Profile Additives (LPAs) which are effective against volume shrinkage during curing of free radical crosslinkable polymer compositions. When relatively small amounts of LPA are used in free-radically crosslinkable polymer compositions, sufficient shrink control should also be achieved during curing, if possible. Furthermore, LPA should preferably be block stable. The addition of low molecular weight additives should be avoided if possible.

This object is surprisingly achieved by using as the LPA a copolymer comprising specific amounts of monomeric units of isopropenyl acetate and vinyl acetate.

The invention provides the use of a vinyl acetate-isopropenyl acetate copolymer as a Low Profile Additive (LPA), characterized in that the vinyl acetate-isopropenyl acetate copolymer is based on 2 to 98 wt% of vinyl acetate, 2 to 98 wt% of isopropenyl acetate and optionally one or more other ethylenically unsaturated monomers, in each case based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

The vinyl acetate-isopropenyl acetate copolymer preferably comprises from 50% to 98% by weight, particularly preferably from 65% to 95% by weight, most preferably from 75% to 90% by weight, of vinyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

The vinyl acetate-isopropenyl acetate copolymer preferably comprises from 2 wt% to 50 wt%, more preferably from 5 wt% to 40 wt%, particularly preferably from 8 wt% to 35 wt%, most preferably from 10 wt% to 25 wt% of isopropenyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer. Isopropenyl acetate is also known as 1-methyl vinyl acetate.

Vinyl acetate and isopropenyl acetate are vinyl esters of acetic acid. Based on the total weight of copolymerized vinyl esters in the vinyl acetate-isopropenyl acetate copolymer; in particular, the vinyl acetate-isopropenyl acetate copolymer preferably comprises >95 wt.%, more preferably ≥ 96 wt.%, even more preferably ≥ 98 wt.% and particularly preferably ≥ 99 wt.% of vinyl acetate, especially vinyl acetate and isopropenyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

The other ethylenically unsaturated monomers are generally different from vinyl acetate and isopropenyl acetate.

Other ethylenically unsaturated monomers can be, for example, one or more vinyl esters other than vinyl acetate and isopropenyl acetate. Examples of such vinyl esters are: vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, vinyl pivalate and vinyl esters of α -branched monocarboxylic acids having 5 to 13 carbon atoms, for example, VeoVa9R, VeoVa10R or VeoVa11R (trade name of Shell). The vinyl acetate-isopropenyl acetate copolymer preferably comprises <5 wt.%, more preferably < 3 wt.%, particularly preferably < 1 wt.% of vinyl esters other than the vinyl acetate and isopropenyl acetate, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer. Most preferred are vinyl acetate-isopropenyl acetate copolymers that do not contain any vinyl ester units other than the vinyl acetate and isopropenyl acetate.

Preferred further ethylenically unsaturated monomers are ethylenically unsaturated acids or salts thereof, in particular carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid and fumaric acid, maleic acid, fumaric acid or monoesters of maleic acid or salts thereof, for example ethyl and isopropyl esters; ethylenically unsaturated sulfonic acids or salts thereof, preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid; ethylenically unsaturated phosphonic acids or salts thereof, preferably vinylphosphonic acid. Particularly preferred are ethylenically unsaturated carboxylic acids or salts thereof. Acrylic acid, methacrylic acid, crotonic acid are most preferred. The vinyl acetate-isopropenyl acetate copolymer preferably comprises from 0 to 5% by weight, particularly preferably from 0.1% by weight to 3% by weight, and most preferably from 0.5% by weight to 2% by weight, of ethylenically unsaturated acid or salt thereof, based on the total weight of the vinyl acetate-isopropenyl acetate copolymer.

Further examples of other ethylenically unsaturated monomers are one or more monomers selected from the group consisting of methacrylic or acrylic esters of carboxylic acids and linear or branched alcohols having 1 to 15 carbon atoms, vinyl aromatics, vinyl halides, dienes and olefins. Such monomers are preferably copolymerized into the vinyl acetate-isopropenyl acetate copolymer in an amount of < 5% by weight, more preferably < 3% by weight, particularly preferably < 1% by weight, based on the total weight of the vinyl acetate-isopropenyl acetate. It is most preferred that no such monomer is copolymerized into the vinyl acetate-isopropenyl acetate copolymer.

The vinyl acetate-isopropenyl acetate copolymer preferably has a glass transition temperature Tg of from 20 to 70 deg.C, particularly preferably from 30 to 50 deg.C, most preferably from 35 to 45 deg.C. Preferably, the weight ratio of the monomers and the monomers is selected to obtain the glass transition temperature Tg of the vinyl acetate-isopropenyl acetate copolymer described above. The glass transition temperature Tg can be determined in a known manner by Differential Scanning Calorimetry (DSC). Tg can also be approximately pre-calculated by the Fox equation. According to Fox t.g., bull.am. physics soc.1,3, page 123 (1956): 1/Tg ═ x1/Tg1+ x2/Tg2+. + xn/Tgn, where xn is the mass fraction (weight percent/100) of monomer n and Tgn is the glass transition temperature in kelvin of the homopolymer of monomer n. The Tg values of the homopolymers are reported in Polymer Handbook 2nd Edition, J.Wiley & Sons, New York (1975).

The vinyl acetate-isopropenyl acetate copolymer preferably has a molecular weight Mw of 2000-750000 g/mol, particularly preferably of 20000-300000 g/mol, most preferably of 50000-200000 g/mol (determination method: SEC ("size exclusion chromatography"), determined in THF at 60 ℃ using polystyrene standards).

The vinyl acetate-isopropenyl acetate copolymer preferably has a value of 1 to 100mPas, particularly preferably 2 to 20mPas, more preferably 3 to 10mPas, most preferably 5 to 9mPas (m:) (m)Method, measured in 10% strength solution in ethyl acetate solution, at 20 ℃ DIN 53015)Viscosity.

The vinyl acetate-isopropenyl acetate copolymer is preferably not emulsifier-stable and/or preferably not protective colloid-stable.

The vinyl acetate-isopropenyl acetate copolymers can generally be obtained by polymerization of ethylenically unsaturated monomers according to the invention in the presence of free radical initiators, in particular by free-radically initiated bulk, solution or suspension polymerization processes. Particularly preferred is the solution polymerization method. During the solution polymerization process, preference is given to using organic solvents or organic solvent mixtures or mixtures of one or more organic solvents with water as solvent. Preferred solvents are alcohols, ketones, esters, ethers, aliphatic hydrocarbons, aromatic hydrocarbons and water. Particularly preferred solvents are aliphatic alcohols having 1 to 6 carbon atoms, for example methanol, ethanol, n-propanol or isopropanol, ketones such as acetone or methyl ethyl ketone, esters such as methyl acetate, ethyl acetate, propyl acetate or butyl acetate, or water. Methanol, isopropanol, methyl acetate, ethyl acetate and butyl acetate are most preferred.

The polymerization temperature is preferably from 20 to 160 ℃ and particularly preferably from 40 to 140 ℃. In general, the polymerization is carried out under atmospheric pressure, preferably under reflux.

Suitable free-radical initiators are, for example, oil-soluble initiators such as tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, dibenzoyl peroxide, tert-amyl peroxypivalate, bis (2-ethylhexyl) peroxydicarbonate, 1-bis (tert-butylperoxy) -3,3, 5-trimethyl-cyclohexane and bis (4-tert-butylcyclohexyl) peroxydicarbonate. Azo initiators such as azobisisobutyronitrile are also suitable. The initiators are generally used in amounts of from 0.005% by weight to 3.0% by weight, preferably from 0.01% by weight to 1.5% by weight, based in each case on the total weight of the monomers used for preparing the vinyl acetate-isopropenyl acetate copolymer.

The polymerization rate can be controlled, for example, by temperature, initiator, by the use of initiator accelerators or by initiator concentration.

The setting of the molecular weight and the degree of polymerization is known to the person skilled in the art. For example, it can be achieved by adding a chain transfer agent, by the ratio of solvent to monomer, by a change in initiator concentration, by a change in the amount of monomer added, and by a change in polymerization temperature. Chain transfer agents are, for example, alcohols such as methanol, ethanol and isopropanol, aldehydes or ketones such as acetaldehyde, propionaldehyde, butyraldehyde, acetone or methyl ethyl ketone, or other mercapto-containing compounds, for example, dodecyl mercaptan, mercaptopropionic acid or mercapto-containing silicones.

The polymerization can be carried out by initially introducing all or each component of the reaction mixture, or by partially initially introducing and further feeding all or each component of the reaction mixture, or by metering in the course of the feed process without initial feeding.

Volatile residual monomers or other volatile components can be removed, for example, by distillation or stripping process methods, preferably under reduced pressure.

The invention further provides radically crosslinkable polymer compositions comprising

a) At least one crosslinkable unsaturated polyester resin (UP resin) or vinyl ester resin (VE resin),

b) at least one monomer having an ethylenically unsaturated group (reactive monomer),

c) at least one initiator, in particular a peroxide or hydrogen peroxide,

d) optionally one or more promoters such as cobalt-or amine-based promoters,

e) optionally a fibrous material, which is,

f) optionally fillers, in particular mineral fillers, and

g) optional additives, characterized in that one or more vinyl acetate-isopropenyl acetate copolymers according to the invention are additionally present.

The vinyl acetate-isopropenyl acetate copolymer is used as LPA in free-radical crosslinkable polymer compositions.

The free-radically crosslinkable polymer composition preferably comprises the vinyl acetate-isopropenyl acetate copolymer in an amount of from 2% by weight to 20% by weight, particularly preferably from 4% by weight to 16% by weight, based on the total weight of resin a) and monomer b) and vinyl acetate-isopropenyl acetate copolymer.

The vinyl acetate-isopropenyl acetate copolymers are generally used in the form of 10% to 70% strength by weight solutions, preferably 30% to 55% strength by weight solutions, in ethylenically unsaturated monomers, preferably styrene or methacrylates, such as Methyl Methacrylate (MMA), 1, 3-butanediol dimethacrylate (1,3-BDDMA) and 1, 4-butanediol dimethacrylate (1, 4-BDDMA). The vinyl acetate-isopropenyl acetate copolymer is particularly preferably used as a 35 wt.% to 55 wt.% strength solution in styrene, 1,4-BDDMA or 1, 3-BDDMA.

In order to improve the mechanical strength after curing, it is possible to add 1% to 20% by weight, based on the vinyl acetate-isopropenyl acetate copolymer, of a polyfunctional acrylate or methacrylate, such as trimethylolpropane trimethacrylate (TMPTMA), to the solution.

The components a) to g) and the amounts used in the free-radical crosslinkable polymer compositions can in principle be selected by the person skilled in the art in a conventional manner according to the requirements of the respective application.

Unsaturated polyester resins (UP resins) suitable as resins a) can generally be obtained by polycondensation of unsaturated and saturated dicarboxylic acids or dicarboxylic anhydrides with polyhydric alcohols. Vinyl ester resins (VE resins) suitable as resins a) can be obtained, for example, by esterification of epoxy resins with acrylic acid or methacrylic acid. Suitable UP resins and VE resins are also commercially available.

The free-radically crosslinkable polymer composition also comprises monomers b) having ethylenically unsaturated groups, generally styrene or methacrylate monomers such as Methyl Methacrylate (MMA) or 1, 3-and 1, 4-butanediol dimethacrylate (1,3-BDDMA/1, 4-BDDMA). These monomers can be added to the free-radically crosslinkable polymer composition, for example, to dissolve the crosslinkable resin a) or to convert the free-radically crosslinkable polymer composition into flowable substances.

The addition of the initiator c) to the free-radically crosslinkable polymer composition is generally used to initiate crosslinking of the unsaturated polyester or vinyl ester resin. It is possible to use conventional peroxides or hydroperoxides, for example cumene hydroperoxide, dibenzoyl peroxide or methyl ethyl ketone peroxide, in conventional amounts.

The free-radical crosslinkable polymer composition optionally also comprises an accelerator d). The accelerator d) can be used to accelerate the decomposition of the initiator. Suitable accelerators and the amounts thereof are generally known to the person skilled in the art and are, for example, commercially available as cobalt salts, in particular cobalt octoate, cobalt neodecanoate or cobalt naphthenate. Preferred free-radically crosslinkable polymer compositions do not contain any accelerator d).

The free-radical crosslinkable polymer composition may optionally comprise fibrous materials e) or fillers f) or additives such as processing aids, in particular thickeners.

Suitable fiber materials e) are, for example, glass fibers, carbon fibers, natural fibers or corresponding fiber mats (fiber-reinforced plastic composite material — FRP composite material). The reinforcement of the composite treatment component obtained by curing of the free-radical crosslinkable polymer composition can be achieved using such a fiber material.

The present invention also provides composite components obtainable by curing the free-radical crosslinkable polymer compositions of the invention.

The curing of the radically crosslinkable polymer compositions is preferably carried out at temperatures of ≥ 40 ℃, particularly preferably from 60 to 180 ℃, most preferably from 70 to 130 ℃. The curing is preferably carried out by free-radically initiated polymerization in the presence of one or more initiators. The free-radically crosslinkable polymer composition is optionally pressed during curing under the application of a pressure of ≥ 1 mbar, particularly preferably from 1 to 200000 mbar, and most preferably 1000-.

The composite components can be obtained from the radically crosslinkable polymer compositions by all customary production process methods, for example by sheet molding compounding technology (SMC), bulk molding compounding technology (BMC), Resin Transfer Molding (RTM), pultrusion, continuous lamination or Resin Injection Molding (RIM). The free-radically crosslinkable polymer compositions according to the invention can be processed by customary methods known per se to give composite components.

When used as LPA in free-radically crosslinkable polymer compositions, the isopropenyl acetate-vinyl acetate copolymers according to the invention show a surprisingly strong shrinkage-reducing effect during curing of the polymer composition. This is the case even when only relatively small amounts of isopropenyl acetate-vinyl acetate copolymer are added to the free-radically crosslinkable polymer composition. Furthermore, the LPAs of the present invention are also surprisingly block stable, even without the addition of antiblocking agents such as carbonates, talc, gypsum, silica, kaolin or silicates. The LPA according to the invention can also advantageously be granulated and provided in the form of block-stable pellets. All these effects are all the more surprising, since isopropenyl acetate is structurally similar to vinyl acetate and the proportion according to the invention of isopropenyl acetate units in the LPA according to the invention still considerably improves its LPA efficiency.

Detailed Description

The following examples are intended to further illustrate the invention, but are not intended to limit the invention in any way.

Preparation of vinyl acetate-isopropenyl acetate copolymer:

example 1:

VAc-IPAc copolymer containing 5% IPAc (LPA 1):

712.5g of vinyl acetate, 37.5g of isopropenyl acetate and 450g of methanol are placed in a 2-liter stirred glass kettle equipped with an anchor stirrer, reflux condenser and metering device. The initial charge was then heated to reflux under nitrogen at a stirring speed of 200 rpm. After reflux had been reached, 11g of initiator PPV (tert-butyl perpivalate, 75% strength solution in aliphatic compound) in 16.5g of methanol were added over 300 minutes. To reduce the viscosity, methanol was added at different time points: 200g were added 195 minutes after reflux was reached and another 200g after 90 minutes. After cooling, the resulting copolymer was dried.

The copolymer being determined according to DIN 53015Viscosity (10% in ethyl acetate at 20 ℃) 7.2mPas, number average molecular weight M_n24700 g/mol, a weight-average molecular weight M_w114.300g/mol, as determined by size exclusion chromatography in THF at 60 ℃ relative to polystyrene standards with narrow size distribution. The glass transition temperature Tg (determined by Differential Scanning Calorimetry (DSC)) of this copolymer was 38.7 ℃.

Example 2:

VAc-IPAc copolymer containing 15% IPAc (LPA 2):

637.5g of vinyl acetate, 112.5g of isopropenyl acetate and 187.5g of methanol were placed in a2 l stirred glass kettle equipped with an anchor stirrer, reflux condenser and metering device. The initial charge was then heated to reflux under nitrogen at a stirring speed of 200 rpm. After reflux had been reached, 11g of initiator PPV (tert-butyl perpivalate, 75% strength solution in aliphatic compound) in 16.5g of methanol were added over 300 minutes. To reduce the viscosity, methanol was added at different time points: 100g was added 250 minutes after reflux was reached, 100g after 45 minutes, 50g after 85 minutes, 100g after 20 minutes and 100g after 25 minutes. After cooling, the resulting copolymer was dried.

The copolymer being determined according to DIN 53015Viscosity (10% in ethyl acetate at 20 ℃) of 8.7mPas, number average molecular weight M_n34000 g/mol, its weight-average molecular weight M_w143100 g/mol, as determined by size exclusion chromatography in THF at 60 ℃ relative to polystyrene standards with narrow size distribution. The glass transition temperature Tg (determined by Differential Scanning Calorimetry (DSC)) of this copolymer was 41.3 ℃.

Example 3:

VAc-IPAc copolymer containing 30% IPAc (LPA 3):

622.4g of vinyl acetate, 266.8g of isopropenyl acetate and 44.5g of methanol are placed in a2 liter stirred glass kettle equipped with an anchor stirrer, reflux condenser and metering device. The initial charge was then heated to reflux under nitrogen at a stirring speed of 150 rpm. After reflux had been reached, 10.7g of initiator PPV (tert-butyl perpivalate, 75% strength solution in aliphatic compound) in 16.1g of methanol were added over 390 minutes. If the viscosity increases greatly, the viscosity is reduced by intermittent addition of methanol (see examples 1 and 2). After cooling, the resulting copolymer was dried.

The copolymer being determined according to DIN 53015Viscosity (10% in ethyl acetate at 20 ℃) of 6.3mPas, number average molecular weight M_n35600 g/mol, its weight-average molecular weight M_w117100 g/mol, as determined by size exclusion chromatography in THF at 60 ℃ relative to polystyrene standards with narrow size distribution. The glass transition temperature Tg (determined by Differential Scanning Calorimetry (DSC)) of this copolymer was 42.9 ℃.

Example 4:

VAc-IPAc copolymer containing 30% IPAc and additionally 1% crotonic acid (LPA 4):

363.4g of vinyl acetate, 158.0g of isopropenyl acetate, 5.3g of crotonic acid and 0.26g of the initiator TBPEH (tert-butyl peroxy-2-ethylhexanoate) were placed in a2 l stirred glass kettle equipped with an anchor stirrer, reflux condenser and metering device. The initial charge was then heated to reflux under nitrogen at a stirring speed of 200 rpm. After reflux had been reached, 4.9g of initiator PPV (tert-butyl perpivalate, 75% strength solution in aliphatic compound) in 7.4g of methanol were added over 300 minutes. If the viscosity increases greatly, the viscosity is reduced by intermittent addition of methanol (see examples 1 and 2). After cooling, the resulting copolymer was dried.

The copolymer being determined according to DIN 53015Viscosity (10% in ethyl acetate at 20 ℃) 4.9mPas, number average molecular weight M_n26000 g/mol, and a weight-average molecular weight M thereof_wAt 96800 g/mol, as determined by size exclusion chromatography in THF at 60 ℃ relative to polystyrene standards with narrow size distribution. The glass transition temperature Tg (determined by Differential Scanning Calorimetry (DSC)) of the copolymer was 46.0 ℃.

Testing of vinyl acetate-isopropenyl acetate copolymers as shrinkage reducing additives (LPA):

1) UP resin compositions with low LPA content and cured at 120 ℃:

the mixture was prepared from the starting materials shown in table 1 and briefly degassed. Determination of the Density D of the degassed mixture_VThe mixture was then poured into a mold, cured at 120 ℃ for 2 hours, and subsequently post-cured at room temperature for 24 hours. Finally, the density D of the cured molded article was measured_H. Shrinkage was determined by comparing the density D of the mixture before curing_VAnd density D of the molded article after curing_HUsing the formula shrinkage (%) ═ D_H-D_V/D_H) X 100 (Table 2). Negative values indicate that the cured molded article is larger than the original mold.

Density measurement was performed at 23 ℃ using a densitometer DMA 38 (trade name of Anton Paar).

Table 1: crosslinkable polymer composition:

*：17-02: the alias trade name;

**：i-200: united Initiators are tradenames.

The following materials were used as Low Profile Additives (LPA):

LPAV1 (comparative example):b100 SP (trade name of Wacker Chemie, ethylene acetate homopolymer, Mw 100000 g/mol);

LPA 1: example 1 (5% IPAc);

LPA 2: example 2 (15% IPAc);

LPA 3: example 3 (30% IPAc);

LPA 4: example 3 (30% IPAc, 1% crotonic acid);

LPAV2 (comparative example):c501 (trade name of Wacker Chemie, carboxylated polyvinyl acetate, Mw 135000 g/mol).

As can be seen from table 2, conventional LPA (LPAV1) is not effective at this low concentration.

On the other hand, the VAc-IPAc copolymers LPA1, LPA2 and LPA3 according to the invention show a significant reduction in shrinkage at the same addition level, and as the proportion of IPAc in the copolymer increases, the LPA effect increases and even a weak expansion is observed with 30% IPAc. The VAC-IPAc-crotonic acid terpolymer LPA4 comprising 30% IPAc and 1% crotonic acid according to the invention also showed excellent shrinkage compensation as low as 0.4%.

Table 2: shrinkage of molded article:

2) UP resin composition with medium LPA content and cured at 120 ℃:

the mixture was prepared from the raw materials shown in table 3 and briefly degassed. Determination of the Density D of the degassed mixture_VThe mixture was then poured into a mold, cured at 120 ℃ for 2 hours, and subsequently post-cured at room temperature for 24 hours. Finally, the density D of the cured molded article was measured_H. Shrinkage was determined by comparing the density D of the mixture before curing_VAnd density D of the molded article after curing_HUsing the formula shrinkage (%) ═ D_H-D_V/D_H) X 100 (Table 4). Negative values indicate that the cured molded article is larger than the original mold.

Density measurement was performed at 23 ℃ using a densitometer DMA 38 (trade name of Anton Paar).

Table 3: crosslinkable polymer composition:

*：17-02: the alias trade name;

**：i-200: united Initiators are tradenames.

Table 4: shrinkage of molded article:

as can be seen from table 4, while the conventional LPA (LPAV1) was effective at moderate LPA content, the VAc-IPAc copolymers LPA1, LPA2 and LPA3 according to the present invention showed significantly improved shrinkage reduction or even significant swelling. As the proportion of IPAc in the copolymer increases, the shrinkage decreases significantly or the volume increase increases significantly.

3) UP resin composition with medium LPA content and cured at 80 ℃:

the mixture was prepared from the raw materials shown in table 3 and briefly degassed. Determination of the Density D of the degassed mixture_VThe mixture was then poured into a mold, cured at 80 ℃ for 2 hours, and subsequently post-cured at room temperature for 24 hours. Finally, the density D of the cured molded article was measured_H. Shrinkage was determined by comparing the density D of the mixture before curing_VAnd density D of the molded article after curing_HUsing the formula shrinkage (%) ═ D_H-D_V/D_H) X 100 (Table 5). Negative values indicate that the cured molded article is larger than the original mold.

Density measurement was performed at 23 ℃ using a densitometer DMA 38 (trade name of Anton Paar).

As can be seen from table 5, while the conventional LPA LPAV1 was effective at moderate LPA content, the VAc-IPAc copolymers LPA1, LPA2 and LPA3 according to the present invention also showed a significantly improved reduction in shrinkage at 80 ℃. The effect of LPA improves with increasing IPAc ratio in the copolymer.

Table 5: shrinkage of molded article:

4) BMC panels were produced using LPA4 and cured at 160 ℃:

the UP resin and all additives (see table 6) except glass fibers and fillers (calcium carbonate) were first premixed in a vessel for 2 minutes using a high speed mixer (resin paste). In one step, the resin paste was premixed with glass fibers and calcium carbonate in a bench scale kneader for 15 minutes.

BMC (bulk molded composite) was then wrapped in a styrene-tight film using an appropriate film and stored at 23 ℃ for 2 days (aging time), followed by placing in a Wickert press (press conditions: 3 minutes, 160 ℃, 730kN press force, 3mm plate thickness).

The BMC panels obtained in this way were tested after cooling to room temperature as follows:

-mechanical properties: flexural E modulus was determined according to DIN EN ISO 1425;

shrinkage values (linear shrinkage): determined by measurement and reported as a percentage value.

The test results are shown in table 7.

Table 6: crosslinkable polymer composition:

*：c501: wacker Chemie tradename, carboxylated polyvinyl acetate, Mw 135000 g/mol;

**：18-03: the Alincys AG trade name;p: tradenames of Arkema;MK 35：Lehmann&voss trade name.

BMC 2 according to the invention containing LPA4 and compositions according to the invention other than the invention containingBMC 1 of C501 showed better surface quality than that of theHigher gloss and lower long and short wave values as shown. In the case of BMC 2, the linear shrinkage was also low. In the case of BMC 2 according to the invention, both the flexural E modulus and the measure of the stiffness of the composite component are improved.

Table 7: and (3) testing results:

BMC board	BMC 1	BMC 2
			Linear shrinkage [% ]]	0.04	0.02
Flexural E modulus [ MPa ]]	12 700	12 800
			Degree of gloss1	81.6	93.7
Long wave2	2.3	1.9
			Short wave2	13.5	9.8

¹Measured using a measuring instrument Byk-Gardner micro-haze plus;

²measured using a Byk-Gardner micro-wave scan measuring instrument.