Organosilicon multi-block copolymer as well as preparation method and application thereof

Abstract

The invention discloses an organic silicon multi-block copolymer as well as a preparation method and application thereof. The main chain structure of the organic silicon multi-element block copolymer is as follows: in a # imgabs0 # formula, W is a high molecular weight polydimethylsiloxane chain segment with the number-average molecular weight of 15000 g / mol to 65000 g / mol, D is a low molecular weight polydimethylsiloxane chain segment with the number-average molecular weight of 375 g / mol to 14900 g / mol, Z is one of alkylene of C1 to C10, arylene of C6 to C20 and heterocyclic radical of C6 to C25, A1 is-NH-or-O-, and A2 is-NH-or-O-. The organic silicon multi-block copolymer disclosed by the invention is good in flexibility, simple in preparation method and low in production cost, and an optical adhesive prepared from the organic silicon multi-block copolymer has the advantages of high optical transmittance, low haze, low glass-transition temperature, excellent bonding performance and the like, and has no abnormity after being dynamically folded for 200,000 times when being used for flexible foldable electronic products.

Description

Technical Field

[0001] The present invention relates to the technical field of organosilicon materials, and in particular to an organosilicon multi-block copolymer and a preparation method and application thereof. Background Art

[0002] In recent years, flexible foldable electronic products (such as foldable screen mobile phones) have been deeply loved by consumers and have become a new trend in the consumer electronics industry. Optical adhesive is a special adhesive used to fill and bond various functional components inside the display module (such as flexible circuit boards, OLEDs, polarizers, touch panels, cover plates, etc.), and is one of the key materials in flexible foldable electronic products. Silicone optical adhesives have the advantages of good high and low temperature resistance, good weather resistance, and hydrophobicity (low surface energy). Compared with the widely used polyacrylate optical adhesives, they have broader application prospects. However, the existing silicone optical adhesives generally have the problem of low bonding strength, which cannot fully guarantee the effective bonding of the functional components inside the display module, may cause display failures, and are difficult to fully meet the actual application requirements.

[0003] At present, the methods for increasing the bonding strength of silicone optical adhesives mainly include adding a tackifier (i.e., adding a certain amount of polar components to the silicone pressure-sensitive adhesive formula) and surface treating the bonding substrate (applying a primer or performing a corona treatment on the bonding substrate). However, the effects obtained are difficult to be completely satisfactory, as follows: 1) CN 118580792A discloses an OCA optical adhesive, which uses terminal vinyl siloxane as a main material, a monofunctional acrylate functional monomer as a tackifier, and a multifunctional acrylate monomer as a cross-linking agent, and obtains a silicone optical adhesive by two-step UV curing. The silicone optical adhesive has a high bonding strength on a corona-treated PET substrate, but the bonding strength decreases significantly at 85°C, and the bonding stability of the flexible display module under high temperature cannot be guaranteed; 2) CN 118126656 A discloses a flexible OCA optical adhesive, which is prepared by preparing polyacrylate optical adhesive at the interface of silicone optical adhesive to obtain a multilayered silicone optical adhesive (the outer layer is polyacrylate optical adhesive, and the inner layer is silicone optical adhesive), which can improve the flexibility and adhesion of the OCA optical adhesive, but the preparation process of the silicone optical adhesive is complicated and cumbersome, and the production cost is high; 3) CN 116239992A discloses a bending-resistant silicone OCA optical adhesive, which uses methyl vinyl polysiloxane and VMQ resin as main materials, and adds methacryloxypropyl trimethoxy silane as a tackifier and hydrogen-containing silicone oil as a cross-linking agent, and obtains a bending-resistant silicone optical adhesive through high-temperature thermal curing, but the bending number of the silicone optical adhesive is small (100,000 times), and the effect of the cross-linking structure on the T of the silicone optical adhesive is ignored. g; 4) Applying a primer to the bonding substrate: This method can effectively enhance the bonding strength, but it increases the complexity of the process and the production time, and also increases the production cost.

[0004] Therefore, it is of great significance to develop a silicone optical adhesive with high bonding strength and high optical transmittance. Summary of the invention

[0005] The object of the present invention is to provide an organosilicon multi-block copolymer and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] An organosilicon multi-block copolymer, the main chain structure is:

[0008] Wherein, W is a high molecular weight polydimethylsiloxane segment with a number average molecular weight of 15000 g / mol to 65000 g / mol, D is a low molecular weight polydimethylsiloxane segment with a number average molecular weight of 375 g / mol to 14900 g / mol, and Z is C 1 ~C 10 Alkylene, C 6 ~C 20 Arylene, C 6 ~C 25 One of the heterocyclic groups, A 1 is -NH- or -O-, A 2 It is -NH- or -O-.

[0009] Preferably, the structural formula of W is: In the formula, R 1 C 1 ~C 18 Alkyl, C 1 ~C 12 The halogenated alkyl, C 2 ~C 10 The alkenyl group, C 6 ~C 12 One of the aromatic groups of 3 ~C 20 Alkylene, C 6 ~C 20 One of the arylene groups, a is an integer of 200 to 850.

[0010] Preferably, the R 1 C 1 ~C 18 One of the alkyl and phenyl groups.

[0011] More preferably, the R 1 C1 ~C 5 of alkyl.

[0012] Preferably, X is C 3 ~C 20 of alkylene.

[0013] More preferably, X is C 3 ~C 8 of alkylene.

[0014] Preferably, the structural formula of D is: In the formula, R 2 C 1 ~C 18 Alkyl, C 1 ~C 12 The halogenated alkyl, C 2 ~C 10 The alkenyl group, C 6 ~C 12 One of the aromatic groups of 3 ~C 20 Alkylene, C 6 ~C 20 One of the arylene groups, b is an integer of 5 to 199.

[0015] Preferably, the R 2 C 1 ~C 18 One of the alkyl and phenyl groups.

[0016] More preferably, the R 2 C 1 ~C 5 of alkyl.

[0017] Preferably, Y is C 3 ~C 20 of alkylene.

[0018] More preferably, the Y is C 3 ~C 8 of alkylene.

[0019] Preferably, the raw materials for preparing the organosilicon multi-block copolymer are as follows in parts by mass:

[0020] High molecular weight polydimethylsiloxane: 26 to 28 parts;

[0021] Low molecular weight polydimethylsiloxane: 2.5 to 3 parts;

[0022] Isocyanate: 0.5 to 0.7 parts;

[0023] Solvent: 38 to 40 parts;

[0024] Catalyst: 50 ppm to 200 ppm (the mass of the catalyst accounts for parts per million of the total mass of the high molecular weight polydimethylsiloxane, the low molecular weight polydimethylsiloxane, the isocyanate and the solvent).

[0025] Preferably, the isocyanate is at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane dimethylene diisocyanate, metaphenylene diisocyanate, and tetramethylxylene diisocyanate.

[0026] Preferably, the solvent is at least one of toluene, xylene, acetone, butanone, methanol, ethanol, propanol, isopropanol, n-butanol, ethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, cyclohexane, hexane, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, pyridine, methyl formate, ethyl acetate, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and dioxane.

[0027] Preferably, the catalyst is at least one of dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, and didodecylthiodibutyltin.

[0028] A method for preparing the above-mentioned organosilicon multi-block copolymer comprises the following steps:

[0029] 1) dissolving high molecular weight polydimethylsiloxane and a catalyst in a solvent, and then adding isocyanate to react;

[0030] 2) Adding low molecular weight polydimethylsiloxane to the reaction solution of step 1) to react, thereby obtaining an organosilicon multi-block copolymer.

[0031] Preferably, the reaction in step 1) is carried out at room temperature (25°C±5°C) or at a temperature of 50°C to 60°C, and the reaction time is 1h to 2h.

[0032] Preferably, the reaction in step 2) is carried out at room temperature or at a temperature of 50° C. to 60° C., and the reaction time is 1 h to 2 h.

[0033] An optical adhesive comprises the above-mentioned organosilicon multi-block copolymer and a tackifying resin.

[0034] Preferably, the mass ratio of the organosilicon multi-block copolymer to the tackifying resin is 1:0.05-1.

[0035] Preferably, the tackifying resin is MQ silicone resin.

[0036] More preferably, the tackifying resin is an MQ silicone resin having an M / Q value of 0.7-1.

[0037] A method for preparing the optical adhesive as described above comprises the following steps:

[0038] Firstly, an organosilicon multi-block copolymer is prepared, and then mixed with a tackifying resin to obtain an optical adhesive;

[0039] Alternatively, a tackifying resin is added during the preparation of the silicone multi-block copolymer (high molecular weight polydimethylsiloxane, low molecular weight polydimethylsiloxane, isocyanate and solvent will not react with the tackifying resin, so the tackifying resin can be added at any stage of the preparation of the silicone multi-block copolymer), and the preparation of the silicone multi-block copolymer and the mixing of the silicone multi-block copolymer and the tackifying resin are carried out simultaneously to obtain an optical adhesive.

[0040] A flexible foldable display device adopts an optical adhesive containing the above-mentioned organosilicon multi-block copolymer.

[0041] The beneficial effects of the present invention are: the organosilicon multi-block copolymer of the present invention has good flexibility, a simple preparation method, and low production cost; the optical adhesive made therefrom has the advantages of high optical transmittance, low haze, low glass transition temperature, excellent bonding performance, etc.; it is used for flexible foldable electronic products and has no abnormalities after 200,000 dynamic foldings, and is suitable for large-scale industrial production and application.

[0042] Specifically:

[0043] 1) The organosilicon multi-block copolymer of the present invention contains high molecular weight polydimethylsiloxane segments and low molecular weight polydimethylsiloxane segments, which can give the organosilicon multi-block copolymer excellent flexibility;

[0044] 2) The optical adhesive of the present invention makes full use of the microphase separation characteristics of the silicone structure and the carbamate group (or urea group), uses a high molecular weight polydimethylsiloxane segment as the first unit soft segment, and a low molecular weight polydimethylsiloxane segment as the second unit soft segment, which can effectively improve the problem of low bonding strength existing in traditional silicone optical adhesives;

[0045] 3) The optical adhesive of the present invention has the advantages of high optical transmittance, low haze, low glass transition temperature, excellent bonding performance, etc. It is used for flexible foldable electronic products and has no abnormalities after 200,000 dynamic foldings. There is no need to perform primer coating or corona treatment on the bonding substrate, and the bonding strength of the silicone optical adhesive can be greatly improved. The preparation process of the silicone multi-block copolymer used is simple and the preparation cycle is short, which is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1This is the ATR-FTIR graph of the organosilicon multi-block copolymer in Example 1.

[0047] Figure 2 Schematic diagram of the composition of the optical adhesive in Example 1. DETAILED DESCRIPTION

[0048] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0049] Embodiment 1:

[0050] An organosilicon multi-block copolymer, the raw materials for its preparation are shown in the following table:

[0051] Table 1 Raw materials for the preparation of organosilicon multi-block copolymers

[0052]

[0053]

[0054] The preparation method of the above-mentioned organosilicon multi-block copolymer is as follows:

[0055] 1) High molecular weight polydimethylsiloxane and dibutyltin dilaurate were dissolved in toluene by stirring, and then dicyclohexylmethane diisocyanate was added and stirred at room temperature for 2 hours;

[0056] 2) Add low molecular weight polydimethylsiloxane to the reaction solution of step 1) and stir at room temperature for 2 hours to obtain an organosilicon multi-block copolymer.

[0057] The attenuated total reflection Fourier transform infrared spectrum (ATR-FTIR) of the organosilicon multi-block copolymer in this embodiment is shown in FIG. Figure 1 (The inset in the figure is a local enlarged view).

[0058] Depend on Figure 1 It can be seen that no -1 The characteristic infrared absorption peak of isocyanate group (-N=C=O) at 1500 cm indicates that there is no -NCO residue in the organosilicon multi-block copolymer. The presence of urea group (Urea) in the organosilicon multi-block copolymer can be seen by the wavelength range of 1500 cm -1 ~1700cm -1 and 3250cm -1 ~3400cm -1 The infrared characteristic absorption peaks that appeared can be attributed to the stretching vibration of C=O, the deformation vibration of C-NH and the stretching vibration of NH. The stretching vibrations of Si-C, Si-O, Si-O-Si and CH groups in the organosilicon multi-block copolymer correspond to the wave numbers of 862 cm-1, 862 cm-2 and 862 cm-3, respectively. -1 、1010cm-1 、1085cm -1 and 2963cm -1 The characteristic infrared absorption peak at .

[0059] An optical adhesive (composition diagram as shown in Figure 2 The preparation method thereof is as follows:

[0060] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above organosilicon multi-block copolymer and stirred evenly to obtain an optical adhesive.

[0061] Embodiment 2:

[0062] An organosilicon multi-block copolymer, the raw materials for its preparation are shown in the following table:

[0063] Table 2 Raw materials for the preparation of organosilicon multi-block copolymers

[0064]

[0065]

[0066] The preparation method of the above-mentioned organosilicon multi-block copolymer is as follows:

[0067] 1) High molecular weight polydimethylsiloxane and dibutyltin dilaurate were dissolved in toluene by stirring, and then dicyclohexylmethane diisocyanate was added and stirred at room temperature for 2 hours;

[0068] 2) Add low molecular weight polydimethylsiloxane to the reaction solution of step 1) and stir at room temperature for 2 hours to obtain an organosilicon multi-block copolymer.

[0069] An optical adhesive, the preparation method of which is as follows:

[0070] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above organosilicon multi-block copolymer and stirred evenly to obtain an optical adhesive.

[0071] Embodiment 3:

[0072] An organosilicon multi-block copolymer, the raw materials for its preparation are shown in the following table:

[0073] Table 3 Raw materials for the preparation of organosilicon multi-block copolymers

[0074]

[0075] The preparation method of the above-mentioned organosilicon multi-block copolymer is as follows:

[0076] 1) High molecular weight polydimethylsiloxane and dibutyltin dilaurate were dissolved in toluene by stirring, and then dicyclohexylmethane diisocyanate was added and stirred at room temperature for 2 hours;

[0077] 2) Add low molecular weight polydimethylsiloxane to the reaction solution of step 1) and stir at room temperature for 2 hours to obtain an organosilicon multi-block copolymer.

[0078] An optical adhesive, the preparation method of which is as follows:

[0079] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above organosilicon multi-block copolymer and stirred evenly to obtain an optical adhesive.

[0080] Embodiment 4:

[0081] An organosilicon multi-block copolymer, the raw materials for its preparation are shown in the following table:

[0082] Table 4 Raw materials for the preparation of organosilicon multi-block copolymers

[0083]

[0084] The preparation method of the above-mentioned organosilicon multi-block copolymer is as follows:

[0085] 1) High molecular weight polydimethylsiloxane and dibutyltin dilaurate were dissolved in toluene by stirring, and then dicyclohexylmethane diisocyanate was added and stirred at room temperature for 2 hours;

[0086] 2) Add low molecular weight polydimethylsiloxane to the reaction solution of step 1) and stir at room temperature for 2 hours to obtain an organosilicon multi-block copolymer.

[0087] An optical adhesive, the preparation method of which is as follows:

[0088] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above organosilicon multi-block copolymer and stirred evenly to obtain an optical adhesive.

[0089] Comparative Example 1:

[0090] An organic silicon polymer, the raw materials for its preparation are shown in the following table:

[0091] Table 5 Raw materials for the preparation of organosilicon polymers

[0092]

[0093] The preparation method of the above-mentioned organosilicon polymer is as follows:

[0094] High molecular weight polydimethylsiloxane and dibutyltin dilaurate are stirred and dissolved in toluene, and then dicyclohexylmethane diisocyanate is added and stirred at room temperature for 2 hours to obtain an organosilicon polymer.

[0095] An optical adhesive, the preparation method of which is as follows:

[0096] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above-mentioned organosilicon polymer and stirred evenly to obtain an optical adhesive.

[0097] Comparative Example 2:

[0098] An organic silicon polymer, the raw materials for its preparation are shown in the following table:

[0099] Table 6 Raw materials for the preparation of organosilicon polymers

[0100]

[0101] The preparation method of the above-mentioned organosilicon polymer is as follows:

[0102] 1) High molecular weight polydimethylsiloxane and dibutyltin dilaurate were dissolved in toluene by stirring, and then dicyclohexylmethane diisocyanate was added and stirred at room temperature for 2 hours;

[0103] 2) Add ethylenediamine to the reaction solution of step 1) and stir at room temperature for 2 hours to obtain an organosilicon polymer.

[0104] An optical adhesive, the preparation method of which is as follows:

[0105] 30 parts by mass of MQ silicone resin (M / Q value is 0.7; DY-MQ 803 from Shandong Dayi Chemical Co., Ltd.) was added to the above-mentioned organosilicon polymer and stirred evenly to obtain an optical adhesive.

[0106] Performance Testing:

[0107] The optical adhesives in Examples 1 to 4 and Comparative Examples 1 to 2 were allowed to stand for defoaming, then coated on the surface of the PET substrate, heated at 120° C. for 5 min, and then tested for performance. The test results are shown in the following table:

[0108] Table 7 Performance test results of optical adhesive

[0109]

[0110] Note:

[0111] Light transmittance and haze: Place the optical adhesive sample in the middle of the haze meter detector to test its light transmittance and haze. Take 3 areas for each sample, measure 3 times and record the average value.

[0112] Glass transition temperature (T g ): On a stress-controlled rotational rheometer, a cut circular optical adhesive sample (8 mm in diameter) was placed in the middle of a disc-shaped parallel plate, and rheological tests were performed in the linear viscoelastic range of the sample. The test temperature range was -90°C to 50°C, and the glass transition temperature was recorded.

[0113] 180° peel strength / room temperature: refer to "GB / T 2792-1998 Test method for 180° peel strength of pressure-sensitive adhesive tapes" for testing. Cut the optical adhesive sample into strips with a width of 25 mm and a length of 100 mm, stick it on a glass plate and roll it 3 times with a 2kg roller. Let it stand for 20 minutes, and perform 180° peeling 5 times with a tensile testing machine. Record the average value.

[0114] 180° peel force / double 85: Tested with reference to "GB / T 2792-1998 Test method for 180° peel strength of pressure-sensitive adhesive tape", the optical adhesive sample was cut into strips with a width of 25 mm and a length of 100 mm, and attached to a glass plate and rolled 3 times with a 2kg roller, allowed to stand for 20 minutes, and then the strips attached to the glass plate were placed in an environment with a temperature of 85°C and a relative humidity of 85%RH for 2 hours, and peeled 5 times at 180° using a tensile testing machine, and the average value was recorded.

[0115] 200,000 dynamic folds: Cut the optical adhesive sample into strips with a width of 25 mm and a length of 100 mm, fix them in a flip book FPC folding machine, set the test program to 2 seconds / time, and fold 200,000 times. After the test, observe whether the strips are broken, debonded, or whitened.

[0116] It can be seen from Table 7 that: compared with the optical adhesive in Comparative Examples 1-2, the optical adhesive in Examples 1-4 has a lower glass transition temperature and not only exhibits better bonding strength at room temperature, but also exhibits higher bonding strength in extreme environments of high temperature and high humidity. This shows that the present invention adopts a multi-block strategy, in which a high molecular weight polydimethylsiloxane chain segment is used as the first unit soft segment, and a low molecular weight polydimethylsiloxane is further used as the second unit soft segment, thereby giving the silicone multi-block copolymer better flexibility.

[0117] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An organosilicon multi-block copolymer, characterized in that: The main chain structure is: Wherein, W is a high molecular weight polydimethylsiloxane segment with a number average molecular weight of 15000 g / mol to 65000 g / mol, D is a low molecular weight polydimethylsiloxane segment with a number average molecular weight of 375 g / mol to 14900 g / mol, and Z is C1 to C 10 Alkylene, C6~C 20 Arylene, C6~C 25 A1 is -NH- or -O-, and A2 is -NH- or -O-.

2. The organosilicon multi-block copolymer according to claim 1, characterized in that: The structural formula of W is: In the formula, R1 is C1~C 18 Alkyl, C1~C 12 haloalkyl, C2~C 10 Alkenyl, C6~C 12 One of the aromatic groups, X is C3~C 20 Alkylene, C6~C 20 One of the arylene groups, a is an integer of 200 to 850.

3. The organosilicon multi-block copolymer according to claim 1, characterized in that: The structural formula of D is: In the formula, R2 is C1~C 18 Alkyl, C1~C 12 haloalkyl, C2~C 10 Alkenyl, C6~C 12 One of the aromatic groups, Y is C3~C 20 Alkylene, C6~C 20 One of the arylene groups, b is an integer of 5 to 199.

4. The organosilicon multi-block copolymer according to any one of claims 1 to 3, characterized in that: The raw materials for preparing the organosilicon multi-block copolymer are calculated by weight: High molecular weight polydimethylsiloxane: 26 to 28 parts; Low molecular weight polydimethylsiloxane: 2.5 to 3 parts; Isocyanate: 0.5 to 0.7 parts; Solvent: 38 to 40 parts; Catalyst: 50ppm~200ppm.

5. The organosilicon multi-block copolymer according to claim 4, characterized in that: The isocyanate is at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane dimethylene diisocyanate, m-phenylene diisocyanate, and tetramethylphenylene diisocyanate; the solvent is at least one of toluene, xylene, acetone, butanone, methanol, ethanol, propanol, isopropanol, n-butanol, ethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, cyclohexane, hexane, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, pyridine, methyl formate, ethyl acetate, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and dioxane; and the catalyst is at least one of dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, and di(dodecylthio)dibutyltin.

6. A method for preparing an organosilicon multi-block copolymer as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: 1) dissolving high molecular weight polydimethylsiloxane and a catalyst in a solvent, and then adding isocyanate to react; 2) Adding low molecular weight polydimethylsiloxane to the reaction solution of step 1) to react, thereby obtaining an organosilicon multi-block copolymer.

7. An optical adhesive, characterized in that: The composition comprises the organic silicon multi-block copolymer according to any one of claims 1 to 5 and a tackifying resin.

8. The optical adhesive according to claim 7, characterized in that: The tackifying resin is MQ silicone resin.

9. A method for preparing an optical adhesive as claimed in claim 7 or 8, characterized in that: The following steps are involved: Firstly, an organosilicon multi-block copolymer is prepared, and then mixed with a tackifying resin to obtain an optical adhesive; Alternatively, the tackifying resin is added during the preparation of the organosilicon multi-block copolymer, and the preparation of the organosilicon multi-block copolymer and the mixing of the organosilicon multi-block copolymer and the tackifying resin are carried out simultaneously to obtain the optical adhesive.

10. A flexible foldable display device, characterized in that: The optical adhesive used comprises the organosilicon multi-block copolymer described in any one of claims 1 to 5.

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